U.S. patent application number 12/397047 was filed with the patent office on 2009-10-15 for apparatus for the application of a curable composition to a fastener and curable compositions suitable for application to a fastener.
This patent application is currently assigned to Loctite (R&D) Limited. Invention is credited to Martin J. Fitzpatrick, Fergal A. Gordon, Matthias Haller, Karen O'Flynn, Peter Wrobel.
Application Number | 20090255594 12/397047 |
Document ID | / |
Family ID | 31985975 |
Filed Date | 2009-10-15 |
United States Patent
Application |
20090255594 |
Kind Code |
A1 |
Haller; Matthias ; et
al. |
October 15, 2009 |
APPARATUS FOR THE APPLICATION OF A CURABLE COMPOSITION TO A
FASTENER AND CURABLE COMPOSITIONS SUITABLE FOR APPLICATION TO A
FASTENER
Abstract
An apparatus (1) for the application of a composition curable by
irradiation to a fastener (2) having: a conveyor (3) for conveying
fasteners to an application station (5); an application station
(10) comprising an applicator from which the composition is
dispensed. The conveyor rotates the fasteners past the applicator
for application of composition. The same or another conveyor (8)
conveys the fasteners to an irradiation station (10) and rotates
the fasteners for irradiation thereof. The irradiation station
irradiates and thus cures the composition applied to each fastener.
The invention also provides A curable composition for application
to a threaded article, comprising a dispersion of: (i) components
of a first cure mechanism comprising: (a) a (meth)acrylate
functional monomer component; (b) a (meth)acrylate functional
oligomer component; and (c) a photoinitiator component; (ii)
components of a second cure mechanism comprising: (e) an amine
component; and (f) an encapsulated epoxy resin component; together
with (iii) a thickener component suitable to impart sufficient
viscosity to the uncured composition to maintain the dispersion of
the other components in the composition; wherein the photoinitiator
component is suitable upon irradiation of the composition to
achieve a first cure through the depth of the composition applied
to a threaded article so that a binder matrix is formed with the
components of the second cure mechanism dispersed through the
matrix.
Inventors: |
Haller; Matthias;
(Frankfurt, DE) ; Fitzpatrick; Martin J.; (Dublin,
IE) ; Gordon; Fergal A.; (Co. Kildare, IE) ;
O'Flynn; Karen; (Dublin, IE) ; Wrobel; Peter;
(Dublin, IE) |
Correspondence
Address: |
Loctite Corporation
One Henkel Way
Rocky Hill
CT
06067
US
|
Assignee: |
Loctite (R&D) Limited
Dublin
IE
Henkel AG & Co. KGaA
Duesseldorf
DE
|
Family ID: |
31985975 |
Appl. No.: |
12/397047 |
Filed: |
March 3, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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|
10527152 |
Nov 21, 2005 |
7503979 |
|
|
PCT/IE03/00122 |
Sep 11, 2003 |
|
|
|
12397047 |
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Current U.S.
Class: |
137/565.11 ;
411/258; 522/28 |
Current CPC
Class: |
B05C 5/001 20130101;
B05C 11/10 20130101; B05B 13/0235 20130101; Y10T 137/85986
20150401; B05C 9/14 20130101; B05C 13/025 20130101; C08F 290/06
20130101; B05C 9/02 20130101; B05C 5/02 20130101 |
Class at
Publication: |
137/565.11 ;
522/28; 411/258 |
International
Class: |
B05C 11/10 20060101
B05C011/10; C08L 33/08 20060101 C08L033/08; C08L 33/10 20060101
C08L033/10; F16B 39/00 20060101 F16B039/00 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 11, 2002 |
IE |
2002/0739 |
Claims
1-30. (canceled)
31. A feed supply system for supplying a composition to the
application station of an apparatus for the application of a
composition curable by photoirradiation to a fastener comprising:
(i) a volumetric supply pump for taking product from a product
supply and supplying the composition to the application station in
a volumetrically controlled fashion; and (ii) a control for
controlling the supply rate of the pump.
32. A feed supply system according to claim 31 wherein the
volumetric supply pump is an eccentric rotor pump.
33-34. (canceled)
35. A curable composition for application to a threaded article,
comprising a dispersion of: (i) components of a first cure
mechanism comprising: (a) a (meth)acrylate functional monomer
component; (b) a (meth)acrylate functional oligomer component; and
(c) a photoinitiator component; (ii) components of a second cure
mechanism comprising: (d) an amine component; and (e) an
encapsulated epoxy resin component; together with (iii) a thickener
component suitable to impart sufficient viscocity to the uncured
composition to maintain the dispersion of the other components in
the composition; wherein the photoinitiator component is suitable
upon photoirradiation of the composition to achieve a first cure
through the depth of matrix is formed with the components of the
second cure mechanism dispersed through the matrix.
36-50. (canceled)
51. A curable composition according to claim 35 wherein component
(e) comprises a tertiary amine.
52-55. (canceled)
56. A curable composition according to claim 35 wherein the mean
diameters of microcapsules in which component (f) is encapsulated
is in the range of about 100 .mu.m to about 140 .mu.m.
57-67. (canceled)
68. A threaded assembly component having applied thereto a
composition according to claim 35.
69. Reciprocally threaded articles having their respective threads
bonded together by the cure product of a composition according to
claim 35.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to an apparatus for the
application of a curable composition to a fastener, especially to a
threaded fastener. In particular, the invention relates to an
apparatus for the application of an at least two stage curable
composition to a fastener. The invention further relates to curable
compositions for application to a fastener, particularly by the use
of the said apparatus. In particular the invention relates to
adhesive compositions which are suitable for thread locking or
thread sealing applications. In general the present invention
relates to a polymerisable composition for the sealing and locking
of engineering parts, particularly interfitting parts such as
fasteners, more particularly threaded fasteners such as nuts,
bolts, screws, threaded nails and the like, or parts such as pipe
joints which may be threaded or slip-fitted. Compositions of the
invention may be used to assemble engineering parts where close
tolerances are designed between adjacent surfaces of the parts. The
invention particularly relates to pre-applied compositions.
[0003] 2. Brief Description of Related Technology
[0004] It is known to provide an apparatus for applying material to
fasteners, in particular, threaded fasteners. One of the problems
which have been associated with conventional apparatus for applying
a composition includes the problem of contact marks. Contact marks
arise where fasteners touch off each other during the coating
process. If the coating is not dry to touch then some of the
coating may come off onto another fastener, leaving a mark where
contact was made (on one or both fasteners). Such marks are known
as contact marks.
[0005] One of the reasons for eliminating contact mark problems
includes improving the appearance of the end product. In
particular, it is desirable that fasteners will have composition
only where it is required and will not have small amounts of the
composition on other parts of the fastener, which detract from the
aesthetic appearance of the fasteners.
[0006] Having composition on undesired parts of the fastener can
also deleteriously affect the handling of the fasteners by
automated machines (for example, robotic machines such as robotic
grippers and the like). Due to the continued automation of assembly
lines and the like, it is desirable that fasteners can be handled
by automated machines, for example, machines for placing the
fastener in a fastening position, and/or fastening parts
mechanically with the fasteners. Such automated apparatus will
normally be designed to grip the fastener at a part of the fastener
which has not had composition applied. This is to ensure that
composition does not find its way onto the handling apparatus for
the fastener. However, if composition has made its way onto other
parts of the fastener (as discussed above), then it tends to come
off on the handling apparatus, eventually causing problems with
gripping of fasteners. It may interfere with moving parts of at
least that part of the apparatus which grips the fastener and the
like. Other methods of handling fasteners include pneumatic lines
(often referred to as "shoots") which essentially are hollow tubes
through which the fasteners are blown by compressed air pressure.
The fasteners can clog up in the tubes if the interior of the tubes
becomes soiled with composition due to contact of the fastener with
the tube (contact marks on the interior of the tube). Accordingly
it is desirable that any coating applied is substantially dry to
touch when being passed through such systems.
[0007] Certain forms of apparatus which have been provided for
applying coatings to fasteners include a drying oven in the form of
a high temperature oven which is used to dry the composition. There
are inefficiencies in the process, as the amount of energy required
to dry the composition is high. Furthermore, batching the fasteners
together for drying in the oven can lead to contact marks, as
discussed above. Evaporation of water and/or solvent from a
composition by heating may create contaminated extracted air which
is another potential disadvantage.
[0008] It is desirable, therefore, to provide a handling mechanism
that can carry components through both the coating and drying
processes to create a dry-to-touch composition applied to the
fastener without creating an opportunity for contact marks to be
formed by touching (e.g. by collision) of fasteners. It is also
desirable to provide a compact apparatus for application of curable
composition. It is also desirable to provide an apparatus, which
can have high throughput of components, which are coated, suitably
in a compact arrangement.
[0009] One such handling apparatus is described in U.S. Pat. No.
6,027,568 (Wallace et al). Wallace et al. describe an apparatus and
method for providing a masking, insulating and/lubricating barrier
coating on a portion of threads of fasteners. The apparatus employs
applicator guns, which fire a jet of composition onto the
fasteners. The fasteners are conveyed along the apparatus by a
conveyor and are delivered to an oven where they are dried.
Accordingly, it is likely that contact marks would be formed in
batching of the fasteners for drying in an oven. The compositions
applied are not curable.
[0010] UK Patent Application No. GB 2 255 781 (Reactive Industries,
Inc.) describes a composition which is UV-curable and which is
applied to fasteners by an apparatus. The apparatus includes a
conveyor having two spaced apart belts for conveying fasteners from
a loading station past applicators and a heating station to a UV
station. The fasteners are caught between the two belts with two
opposing sides at the head of the fastener resting on the top of
the belts and the stem of the fastener depending vertically
downwards in which position the fasteners are held throughout the
processing steps.
[0011] UK Patent Application No. GB 2 255 781 (Reactive Industries,
Inc.) already mentioned above describes a composition comprising a
hardener-containing component which includes (a) a hardener capable
of polymerising a resin, e.g., an epoxy resin; (b) a UV curable
film-forming compound comprising a dimethacrylate; and (c) a
photoinitiator compound capable upon exposure to UV light of curing
(b) to form an integral, thin continuous, dry, substantially
pin-hole free, flexible, non-tacky outer protective skin. The
hardener containing component is preferably fluid and
microencapsulated and can be used in an adhesive system
additionally comprising a resin-containing component which includes
(1) a resin, e.g., an uncured epoxy resin which is polymerisable by
the hardener component, (2) a UV-curable film-forming compound,
e.g., a dimethacrylate; and (3) a photoinitiator capable upon
exposure to UV light of curing the film-forming compound (2) to
form an integral non-tacky outer protective skin. The resin
component may be micro-encapsulated. In this system, also, the UV
curing forms only an outer protective skin and the components for
the second polymerization are free to move beneath the skin or, in
the event of rupture of the skin, to escape from it. The
film-forming compounds used are monomers, particularly
dimethacrylate monomers, and there is no suggestion of use of
oligomers. The rheology of the composition is not discussed and, in
particular, the use of a thickener is not mentioned.
[0012] Compositions which are suitable for use in threadlocking
applications are known. Such compositions find use in many
applications. In general the compositions are used as described
above to lock interengaging threads together. The composition is
generally placed on one or both of components which have reciprocal
interengaging screw threads. When the components are screwed
together using the screw threads the composition acts to lock the
threads in the desired interengaged position.
[0013] In general the applications in which compositions of the
present invention are used include any application where it is
desired to lock screwthreads together so that the components which
are screwed together do not become disengaged unintentionally, for
example because of vibrational or other forces. Such applications
include use in the construction of automobiles etc.
[0014] Compositions have been used which must be applied at the
time of threading one component into another, as the compositions
remain substantially liquid before cure. Such compositions include
anaerobically curable compositions.
[0015] A pre-applied composition is described in U.S. Pat. No.
4,059,136, where two physically separated deposits are applied to
the threaded part. A cover coating is then applied over the
deposits.
[0016] European Patent No. 0 077 659 (Thompson) describes a
pre-applied polymerisable fluid for sealing and locking engineering
parts. The composition has two mechanisms for curing and two curing
reactions take place. The first mechanism is a UV light cure. An
opacifier is dispersed in the fluid so that the fluid becomes
substantially opaque to radiation. After the fluid is applied to
the component it is exposed to UV radiation whereupon a coating is
formed, creating a surface layer which is a dry, tack-free crust.
The subcutaneous fluid is unaffected by the radiation and remains
in a generally liquid state. When the component is threaded into
another the surface layer breaks and the second polymerisation
(such as a free radical addition polymerization) is initiated and
the second cure reaction takes place. The second polymerisation
mechanism acts to lock the threads together.
[0017] In Thompson, only a skin is formed in the first
polymerization and the remainder of the composition remains fluid
below the skin. There is a risk therefore that during handling of
the coated engineering parts the skin may be disrupted and the
fluid composition may leak out.
[0018] European Patent No. 0 548 369 (Usami) describes a
pre-applied adhesive composition for application to the threaded
contact faces of a screw member such as a screw. The composition
comprises a photo-hardening binder in which a secondary curable
composition is dispersed. The secondary curable composition
includes microencapsulated reactive monomer/activator/initiator.
Exemplified compositions include those containing (i)
microencapsulated bisphenol A dimethacrylate and a radical
generator; (ii) microencapsulated bisphenol A dimethacrylate and
DMPT; and (iii) Three Bond product no. 3057D. The only information
given about the product 3057D is that it is a UV-hardening acrylic
resin containing a photoinitiator. Other similar compositions are
disclosed in the other "Embodiments" described. In two
"Embodiments" bisphenol A epoxy resin is encapsulated. In one of
these "Embodiments", the microencapsules enclosing bisphenol A
epoxy resin are used with Three Bond product no. 3057D, salicyclic
acid derivative and aromatic diamine. The present applicants have
not been able to obtain a sample of Three Bond product 3057D and
therefore have no information about the acrylic resin contained in
it. In the other "Embodiment", the microcapsules enclosing
bisphenol A epoxy resin are used with dialkylamino-acrylamide and a
photoinitiator (DAROCURE 1173). There is a general indication in
the description that a filler may be added but no filler is used in
the "Embodiments". There is no suggestion of using a thickener, nor
is there any enabling teaching about the acrylic resin. So far as
the present applicants are aware, no product has been
commercialised under the European Patent No. EP 0 548 369.
[0019] Notwithstanding the various compositions that have been
provided it is desirable to provide an alternative composition
which is suitable for use in thread sealing/thread locking
applications. It is desirable that such compositions are suitable
for pre-application to threaded articles, for example to bolts, for
later use. It is desired that the composition can be applied to
form a dry-to-touch product on the threaded article. It is also
desirable that the composition can be later activated to lock
threaded articles together with desirable properties of the bond
formed between the threaded articles. To achieve this the
composition must be storage stable before application and then
remain stable for subsequent use.
SUMMARY OF THE INVENTION
[0020] The present invention defines an apparatus and system for
the application to a fastener of a composition curable by
irradiation.
[0021] Accordingly, the present invention provides an apparatus for
the application of an at least two-stage curable composition to a
fastener comprising: [0022] (i) a conveyor for conveying fasteners
to an application station; [0023] (ii) an application station
comprising an applicator from which the composition is dispensed,
the conveyor for rotating at least part of the fasteners past the
applicator for application of composition to the fasteners; [0024]
(iii) a conveyor for conveying the fasteners to an irradiation
station and arranged to rotate the fasteners for irradiation
thereof; and [0025] (iv) an irradiation station for curing the
composition applied to each fastener.
[0026] The apparatus of the present invention is able to handle and
coat various types of threaded parts, in particular, male threaded
parts. The flexibility of the apparatus to coat large numbers of
different parts is quite advantageous. The end-users of the parts
may require an approval procedure for each type of part they use.
Accordingly, if the parts are coated by different procedures, a
different approval procedure may be required. This is not so with
the present invention, where the same apparatus can handle
different sizes of fasteners.
[0027] The apparatus of the invention is suited to high production
speed, for example, greater than 16,000 pieces per hour. The
apparatus may be quite compact, for example, no longer than 2
metres in length. For example typical dimensions including a
feeding station are 2 m.times.2 m.times.1.5 m
(height.times.length.times.width). This reduces installation and
user space required. The apparatus is also relatively portable,
being quite easily moved from one location to another.
[0028] The conveyor for conveying fasteners to an application
station may be the same conveyor as the conveyor for conveying the
fasteners to an irradiation station. Desirably however they are
separate (first and second) conveyors (conveyors which can run at
different speeds for application and curing). In particular it is
desirable that the apparatus comprises a first conveyor for
conveying fasteners to an application station, and for rotating at
least part of the fasteners past the application station for
application of composition to the fasteners. Suitably the first
conveyor rotates the fasteners and conveys at least part of the
rotating fasteners past the application station. The second
conveyor can then be used to convey the fasteners to irradiation
station. While most of the discussion of the present invention
refers to the presence of first and second conveyors it will be
appreciated that the features of the first and second conveyors may
be applied, as appropriate, to a single conveyor apparatus.
[0029] In one desirable arrangement the apparatus further comprises
a fastener feeder for feeding fasteners one by one to a first
conveyor. This allows for timely and orderly feeding of fasteners
to the first conveyor. Many conveyors are of the movable support
type, i.e., of the type that support the material they carry. One
example is a flat rubber belt which can carry product on its upper
surface. Such conveyors do not normally continuously rotate (or
roll) the material they carry. Conveyors which continuously rotate
(or roll) the products they handle are desired for use in the
present invention.
[0030] It has been found by the present inventors that it is
desirable to adjust the temperature of the articles to which the
composition is to be applied prior to the application thereof.
Accordingly it is desired to include temperature adjustment means
for adjusting the temperature of the articles to which composition
is to be applied.
[0031] Depending on the product in question it may be necessary to
cool the articles (for example if for any reason (such as ambient
conditions) they are too hot (which for example will make applied
composition less viscous than desired or hot enough to
deleteriously affect the stability of the composition) they may be
cooled. If they are too cold the composition may not move well into
the wells between threads (for example due to increased
viscosity).
[0032] Where it is desired to heat the articles one could therefore
batch heat the articles (for example in an oven) and later supply
them to an apparatus according to the invention for application of
composition.
[0033] However it is desirable to heat the articles in an inline
process for example before they reach, while they are passing
through, or after they exit the fastener feeder. In any event it is
desirable to have the articles heated before they reach the (first)
conveyor.
[0034] Where pre-heating of the articles is desired hot air may be
used to heat them. For example an inline hot air blower may be
employed. One useful piece if equipment includes any hot air blower
which can heat air and which is arranged to deliver a strong
focussed blast of hot air as appropriate to achieve the desired
temperature.
[0035] Conversely for cooling, batch cooling can be employed but
again it is desirable to employ an inline cooling arrangement
analogous to that described above for heating. In particular an air
blower may also be employed. An air blower with a suitable range of
temperatures for the expelled air may be employed to heat or cool
as appropriate. Desirably the articles are at a temperature in the
range from about 30.degree. C. to about 60.degree. C. such as about
35.degree. C. to about 50.degree. C. for example from about
40.degree. C. to about 45.degree. C.
[0036] Pre-setting the temperature of the articles in this way
makes the temperature of the article independent from ambient
temperature.
[0037] The composition should have at least two-stages of cure. The
curable composition having a first cure stage which is activatable
by irradiation so as to fix the composition to a fastener, and a
second cure stage which is curable to secure the fastener in a
fastening position. The irradiation will normally cure the first
stage cure of the composition.
[0038] The first conveyor desirably extends from the fastener
feeder through the application station. The first conveyor may be
arranged for conveying the fasteners in a manner so that the
fasteners are arranged on the conveyor in a configuration each
spaced apart from the next, from the feeder to the application
station (and suitably through the application station).
[0039] In particular it is desirable that the applicator comprises
a surface onto which the product is dispensed. In one construction
the fasteners are rolled across said surface by the first conveyor.
Desirably, the applicator is provided in the form of a coating
block. The coating block will have a surface across which the
fasteners are rolled or such like. In particular, it is desirable
that at least one dimension of the applicator may be altered (the
contact made with the fastener can be varied). This allows the
application of different widths of product to the fasteners. In
particular, the applicator may have a contact portion for
contacting composition to the fastener with a width corresponding
to the width of a continuous coating layer of product that is
desired to apply to the fasteners. In this respect a sufficient
amount of product should be provided in the spaces (pitches or
wells) between threads in the case that the fastener is a threaded
one. A continuous coating layer of product in this respect refers
to sufficient product within the spaces between threads of a
threaded fastener. A certain amount of product may find its way
onto the threads themselves. However it is desirable that the
product does not completely fill or over fill the spaces between
threads.
[0040] The width of the applicator can be varied to achieve
differently sized coating layers of product about the fastener
(usually confined to a portion of the fastener). Product will
normally be continuous both circumferentially about the fastener
and longitudinally along the fastener. It will be appreciated by
those skilled in the art that in an arrangement where the fasteners
are rolled across an applicator (with a contact portion for example
with an application surface thereon) with composition thereon, a
coating layer of product will be applied circumferentially about
the fastener.
[0041] In one embodiment, the applicator surface is adjustable for
application of different extents (coating layers) of product to
fasteners. In another embodiment, the component on which an
applicator surface is formed, for example, a coating block, is an
interchangeable part, so that different applicator surfaces
(coating blocks) are mountable on the apparatus for use. Again this
allows different threaded parts to be processed by the apparatus
with a minimum of equipment alteration.
[0042] Furthermore it is also desirable to have a temperature
control on the applicator. In particular it may be desirable to
heat or cool the applicator surface. The temperature of the
applicator in turn imparts a desired temperature to the composition
which is applied from it. In particular it is useful to control the
applicator temperature in conjunction with controlling the
temperature of the articles to which the composition is to be
applied. Again this makes the application of the composition
independent from ambient temperatures. All heating and/or cooling
means may be controlled by a PLC (programmable logic controller) or
PID (proportional integral differential) controller. Temperature
may be monitored as appropriate for example by employing a suitable
thermocouple.
[0043] In particular it is desired to maintain a temperature
differential between the bolts and the applicator. It has been
found that it is desirable to maintain a temperature difference of
from about 10.degree. C. to about 20.degree. C., such as about
15.degree. C. between the applicator and the articles. In
particular it is desirable that the articles to which the
composition is to be applied are higher in temperature than the
applicator. It has been found that the colder the articles are the
greater the thickness of product applied. However with cold (room
temperature, 15.degree. C. to 25.degree. C.) articles and a
non-heated applicator the amount of product which is applied (the
coating or product layer) may be too great and may cause the
composition applied to overfill the pitches between threads. (The
product "humps" over the threads see for example FIG. 7A.) In
particular it is desired that the composition between threads forms
a concave meniscus shape (see FIG. 7B) so that the composition to
the centre of the pitch is at a lower level than that that at the
threads. In this way the coating efficiency and coating weight are
balanced. The coating weight will be the minimum required to reduce
peel-off and wastage. A coated article will be substantially
completely covered over the entire target (circumferential) area
with a thin even coating. It was found that by employing
temperature as a control on coating weights works well. Suitably
the applicator is at a temperature in the range of 28.degree. C. to
35.degree. C. such as about 30.degree. C.
[0044] In the case where the applicator comprises a coating block
it is desirable that the coating block is temperature controlled
for example by placing heating and/or cooling means in the coating
block. The heating means may be a heating element or cooling
element or may be heated or cooled by circulated fluid such as
water.
[0045] The second conveyor desirably extends through the
irradiation station. The second conveyor may be arranged for
conveying the fasteners in a manner so that the fasteners are
arranged on the conveyor in a configuration each spaced apart from
the next. In particular the second conveyor is used to convey the
fasteners through the irradiation station.
[0046] The fasteners need not be conveyed or otherwise moved
between the first and second conveyors. For example the momentum of
a fastener exiting the first conveyer may be sufficient to carry
the fastener to the second conveyor where it is picked up by motion
of the second conveyor. Larger fasteners (i.e., those with greater
momentum) in particular may be transferred (travel) between
conveyors in this way.
[0047] In one embodiment it is desirable that the apparatus further
comprises a transfer station for transferring the fasteners (from
the first conveyor) to the second conveyor. The transfer station
may comprise a (short) conveyor which acts to convey the fasteners
between the (end of the) first and the (start of the) second
conveyors. This is particularly useful for smaller fasteners.
[0048] In one compact arrangement it is desirable that the total
length of the first and second conveyors is reduced. This may be
achieved by at least partial overlap of the conveyors. In one
arrangement the total distance from a fastener receiving end of the
first conveyor to a fastener exiting end of the second conveyor
measured in a horizontal plane (in the operating position of the
apparatus) may be up to 50% less that the total combined length of
the first and second conveyors.
[0049] One of the advantages in the provision of first and second
conveyors is that the speed of each conveyor to be selected may be
accomplished independently from the other. In particular the speed
of the first conveyor (measured as the travelling speed of a
fastener) is substantially faster than the speed of the second
conveyor. It is also desirable that the first conveyor is arranged
to convey the fasteners with a substantially greater lateral
distance between the fasteners. In one arrangement of the invention
the transfer of the fasteners from the first to the second conveyor
may result in the fasteners being grouped together a smaller
distance apart but in any case it is described that the fasteners
are a shorter distance apart on the second conveyor. For example
the distance between fasteners conveying by the first conveyor is
desirably 4 to 10 times the width of the fastener. (If the fastener
has a head then desirably the spacing is 4 to 6 times the width of
the head.) In the second conveyor the spacing is desirably 1.5 to
2.5 times the width of the fastener (or of the fastener head). The
speed of the first conveyor is typically 2 to 3 times the speed of
the second conveyor. Typical speeds are 0.1 to 0.5 m/s for example
0.22 m/s for the first conveyor or typically has a speed of 0.05 to
0.2 m/s such as 0.09 m/s. The reduction of speed through the second
conveyor and the closer together fasteners allow for a substantial
reduction in the overall length of the first and second conveyors,
thus reducing the overall length of the apparatus.
[0050] In particular at least one and desirably each of the first
and second conveyors of the invention comprise at least one
(endless) belt which is arranged to run substantially constantly
spaced apart from a rail (it is also possible to use an (endless)
chain or such like but a belt is preferred). The belt and the rail
are suitably arranged to grip the fasteners between them so that
motion of the belt (in at least one direction) causes the fasteners
to roll along the rail. In this way the fasteners can be rotated
and moved along at the same time. At least one rail may run from
the applicator station through to the irradiation station.
[0051] Desirably the fastener is a threaded fastener such as a
bolt, screw, plug, stud, fittings and the like. Typically the
threads of the fastener engage with reciprocal threads of a
receiver for the fastener for example a threaded bore or nut and
the composition (in particular stage two thereof) is activated on
screw thread engagement of the fastener to act as a threadlocking
composition to lock the threads together or as a thread sealant
composition to provide a seal about (the threads of) the fastener.
Threadlocking compositions are well known to those skilled in the
art, desirably both the threadlocking and thread sealing
compositions will have the two stage cure system described above.
In particular it is desirable that the composition applied by the
apparatus of the invention is a one-part composition (having a
two-stage cure).
[0052] Desirably, the fasteners are conveyed by at least the first
conveyor (and desirably the second conveyor also) so that they are
substantially horizontal. The fasteners will normally be threaded.
They may or may not have a head. The fasteners may or may not be
ferromagnetic (e.g., steel, brass or stainless steel).
[0053] In one particularly desirable arrangement, the fastener
comprises a first end and a second end with a stem portion between
the first and second ends. Desirably, the apparatus comprises a
rail for supporting the stem of the fastener at least one location
thereon (at least while the fastener is being conveyed by the first
conveyor). Desirably, a rail is provided also, for supporting the
fastener when it is conveyed by the second conveyor.
[0054] In one particularly desirable arrangement, two spaced apart
rails are provided to support the fastener at least two positions
thereon. It is desirable that neither of said two positions
coincides with the part of the fastener which has had, or is for,
application of composition at least until the fastener is
sufficiently far through the apparatus so that the composition is
dry to touch.
[0055] The fasteners may typically be in the range from 5 mm up to
200 mm in length. Such fasteners do not need a head for
transportation or for guidance along the apparatus. The invention
is particularly suitable for use with threaded fasteners having a
head portion and a stem portion thereon.
[0056] In one particularly desirable arrangement, suitably the rail
or rails for supporting the fastener are adjustable so that
different sizes (lengths) of fasteners may be accommodated by the
apparatus. In particular, where two rails are provided, it is
desirable that they are adjustable relative to each other so that
the spacing between the rails may be varied as desired. Such rails
are desirably of a narrow width, for example, between 1 mm and 5 mm
in thickness. Desirably, two parallel rails are provided. Product
may be applied to the portion of the fastener that is arranged to
lie between the rails.
[0057] Desirably, the application station comprising a supply
system for supplying curable composition to the flat applicator
surface. In one embodiment, desirably the component on which the
flat applicator surface is formed has one or more apertures defined
therein which pass to and through the applicator surface so that
the product may be provided through the apertures to the applicator
surface.
[0058] Desirably, the conveyor comprises a belt of material,
desirably flexible material. In particular, it is desirable that
the belt comprises resiliently deformable material, and in one
embodiment of the invention, comprises O ring material. An O ring
is a closed loop of material where the cross section of the
material making up the ring is substantially circular
(O-shaped).
[0059] Desirably the supply system for supplying composition to the
application station contains a product supply, which is operated by
volumetric supply.
[0060] Alternatively or additionally the supply system for
supplying composition to the application station includes a
time/pressure control system such as an air-pressurised line which
pushes product from a product reservoir along a conduit toward the
applicator. In the case where both a time/pressure system and a
volumetric system are employed it is desirable that the
time/pressure system feeds product to the volumetric control
system, which in turn supplies the product to the applicator
station. Desirably, a control is provided for controlling the rate
of product supply.
[0061] It has been found that the inclusion of a volumetric system
results in a much more convenient system as a user of the system
has no longer to continually adjust the supply of the product due
to ambient changes such as pressure/temperature change. In
particular it is difficult with a direct feed to the applicator
station from a time/pressure system to control supply rate where
the product to be supplied is viscous.
[0062] Accordingly the present invention also provides a feed
supply system for supplying a composition to the application
station of an apparatus of the invention the system comprising:
[0063] (i) a volumetric supply pump for taking product from a
product supply and supplying the composition to the application
station in a volumetrically controlled fashion; and [0064] (ii) a
control for controlling the supply rate of the pump.
[0065] Mechanical handling of the product may cause the product to
prematurely cure and thus deleteriously affect the composition and
the apparatus. For example where the composition includes a
microencapsulated component any mechanical handling can cause shear
forces which rupture the microcapsules causing premature curing of
the composition rendering it substandard perhaps to the point of
being completely useless, and also contaminating the apparatus with
the cured product. Neither of these is desirable.
[0066] Surprisingly it has been found that an eccentric rotor pump
can be used as part of the feed supply system of the present
invention, which of course may in turn be used as part of the
apparatus of the present invention.
[0067] Generally an eccentric rotor pump will include a rotor and a
stator, the rotor being a single helix shape and the stator being a
double helix shape. In general the rotor and stator will together
form a closed cavity along which the composition is pushed by
relative rotation of the rotor and the stator.
[0068] In conjunction with such a system it is desirable to
calculate a desired amount of product per fastener and set the
fastener feed rate and the product supply rate. Once the fastener
and the composition to be employed have both been selected the feed
supply can be calibrated so that a desired amount of product can be
provided to the fasteners in a predictive fashion. There will be no
need for continual adjustment of the supply rate for
pressure/temperature differences.
[0069] A conduit which takes the composition from the volumetric
supply pump to the applicator station is desirably both relatively
short and rigid. Reducing the length and avoiding a flexible
conduit (such as a flexible hose) may allow better volumetric
control to be achieved, as flexing of the conduit, particularly
over relatively long lengths can be avoided.
[0070] With a product supply system such as described above the
amount of product to be supplied will (once a fastener type is
selected for application of composition) depend on the rate at
which the fasteners are throughput.
[0071] The applicator desirably has a spreading surface onto which
the composition is dispensed. The spreading surface may or may not
be recessed so that product is present below a surface of the
applicator across which the fasteners are rolled.
[0072] The products coated by the apparatus of the present
invention are dry to touch, and thus can be collected in batches
(in contact with each other) without fear of contact marks
developing on some of the components. The present invention
achieves substantially no contact marks on pieces, which have been
processed by the apparatus of the present invention. For example,
even with 16,000 pieces an hour being processed, very low
percentages of these products would have to be rejected due to
contact marks. Contact marks would generally appear on less than 1%
of the pieces and, in particular, less than 0.1% of pieces using
the process of the invention. Markings on less than 0.035% of
fasteners has been achieved while 0.005% or less is possible (50
pieces in a million).
[0073] Desirably, the irradiation station comprises a UV light
source for irradiating product with UV light. In such instances, it
is desirable that the first cure stage of the curable composition
is activatable by UV light. Desirably, the UV light source is a
high intensity lamp, typically having an output of 120 W/cm. The
fastener may experience an intensity of 40 m/Wcm.sup.2. Desirably
the irradiation station comprises a focused radiation emitting
source, such as for example a focused UV source for example the
light source may be housed in a reflective housing which focuses
the UV light into a narrow coating layer. For larger bolts in
particular the irradiation time is not so critical and a lower
intensity source may be used.
[0074] It will be appreciated by those skilled in the art, that the
limit of the capacity of the apparatus of the present invention to
carry articles for application of coating is limited by the
smallest size of conveyor that can convey the piece and leave
sufficient of the fastener unobstructed for application of a
coating.
[0075] Desirably, the first conveyor and the application station
are arranged in-line.
[0076] The apparatus of the invention is used for application of an
at least two-stage curable composition. In another aspect this
application relates to a composition suitable for use with the
apparatus.
[0077] The present invention provides in one aspect a curable
composition suitable for use in threadlocking applications
comprising:
[0078] (a) a (meth)acrylate functional monomer component;
[0079] (b) a (meth)acrylate functional oligomer component;
[0080] (c) a photoinitiator component;
[0081] (d) a thickener component;
[0082] (e) an amine component; and
[0083] (f) an encapsulated epoxy resin component.
Optionally, additionally the inventive composition may include an
acrylamide component, which may be present within any one or a
number of the components (a) to (f) above or may be present
otherwise. In particular, an acrylamide, such as
N,N-dimethylacrylamide, may suitably be used.
[0084] The inventive compositions have desirable properties, such
as forming a dry to touch (tack-free) product following application
to a threaded component in a liquid state and subsequent UV cure to
its dry state. UV cure of compositions of the invention occurs
right through the depth of the product on the threaded article and
the cured product is not only dry to touch but is substantially dry
(substantially solid) throughout the entire matrix it forms. Within
that matrix the components for the second cure mechanism are
held.
[0085] In particular, compositions of the invention have a first
and second cure mechanisms so that first and second cure reactions
take place. In a first cure mechanism/reaction the composition is
UV hardenable to form a solid binder matrix within which components
of the secondary cure mechanism are held. In particular components
(a)-(d) form the UV hardenable binding matrix. Components (e) and
component (f) (amine and encapsulated epoxy) are the subject of a
second cure mechanism/reaction. These latter components are held
within the binder matrix once a UV cure has been carried out.
[0086] Compositions of the invention should not contain any
opacifier component which renders the composition substantially
opaque to cure-initiating radiation. Cf. Thompson.
[0087] In a particular aspect the present invention provides a
curable composition for application to a threaded article,
comprising a dispersion of:
(i) components of a first cure mechanism comprising:
[0088] (a) a (meth)acrylate functional monomer component;
[0089] (b) a (meth)acrylate functional oligomer component; and
[0090] (c) a photoinitiator component;
(ii) components of a second cure mechanism comprising:
[0091] (e) an amine component; and
[0092] (f) an encapsulated epoxy resin component; together with
(iii) a thickener component suitable to impart sufficient viscocity
to the uncured composition to maintain the dispersion of the other
components in the composition; where the photoinitiator component
is suitable upon irradiation of the composition to achieve a first
cure through the depth of the composition applied to a threaded
article so that a binder matrix is formed with the components of
the second cure mechanism dispersed through the matrix.
[0093] It is important, in particular, that microcapsules
containing the epoxy resin remain dispersed through the composition
before and after the first cure.
[0094] The viscocity of the composition containing components (a)
to (e) but excluding component (f) is suitably within the range of
300 mPas to 3,000 mPas when measured by Haake Roto Visco 1,
C60/1.degree. Cone, shear rate=244 s.sup.-1.
[0095] The second cure mechanism is subsequently activated by
rupture of the microcapsules within the binder resulting in
reaction of amine with the epoxy component which is released from
the microcapsules. The second cure mechanism then acts to lock the
threads together. Good bond strengths are achieved as measured by
the torque required to unlock threaded articles locked to each
other by compositions of the invention from each other.
[0096] Apart from the requirements for suitable cure properties of
the first and second cure mechanisms, there are a number of other
properties the composition should have in order to be particularly
useful as a thread locking or thread sealing composition. One such
property relates to the UV curable portion of the composition. That
portion of the composition should cure to form a flexible but dry
solid on the threaded article to which is applied. Furthermore,
that portion of the composition should also act as a suitable
matrix for the dispersion of the microcapsules and the amine. It
has been found that in compositions of the present invention the UV
curable part of the composition cures to form a dry product with
desired flexibility. Furthermore it acts as an excellent matrix
within which the microcapsules and the amine can be dispersed.
[0097] Flexibility of the UV cure product is desirable so as to
allow for the cured material to be carried with the threads into
contact with the reciprocal threads with which they will be
engaged. If the product is too brittle it will not travel well with
the screw threads and would be inclined to be sheared or pared off
by the screw thread action at the point of entry of one set of
threads with the other and thus not reach the desired location
further down the screw threads. Bond strengths would be poor. If
the material is too soft then it may not be sufficiently robust for
handling and may be removed accidentally, such as in automated
equipment handling. An amount of rupture of the microcapsules might
also result from handling as the microcapsules may not be so well
protected from damage during handling. In general bond strengths
would be poor if epoxy material had (leaked from the microcapsules
and) cured prior to the screw threading action. The compositions of
the present invention demonstrate the required amount of
flexibility without being too brittle in nature.
[0098] In particular it is desirable that the component (a)
comprises an acrylate monomer. Acrylate monomers have been found to
be particularly suitable with the compositions of the present
invention. Any mono-, di-, or tri-functional acrylate may be
employed.
[0099] Specific examples of methacrylate functional monomers which
may be employed in the present invention include: hydroxy
ethylmethacrylate, lauryl methacrylate, isobutyl methacrylate,
hydroxy propyl methacrylate, isobornyl methacrylate and methyl
methacrylate.
[0100] Specific examples of acrylate functional monomers which may
be employed in the present invention include: ethoxylated (3)
phenol monoacrylate such as Photomer 4039 from Cognis;
ethoxyethoxyethyl acrylate; bisphenol A epoxy diacrylate; isobornyl
acrylate; acrylated adhesion monomer such as Craynor 131B from Cray
Valley; a diacrylate such as Photomer 4127F from Cognis;
1,6-hexanediol diacrylate; acrylated polyester adhesion promoter
such as Craynor 704 from Cray Valley; and methylacrylamide; acidic
mono and tri-acrylates such as SR9050, SR9051 from Sartomer. It is
particularly desirable to include an acrylamide, preferably
N,N-dimethylacrylamide, which has been found to contribute to the
cure strength of the product.
[0101] Desirably component (a) comprises a combination of acrylate
functional monomers. In particular it is desirable that component
(a) comprises a combination of mono- and di-functional acrylate.
The cure product of compositions of the invention including a
combination of monomers has been found to have desirable properties
including suitable adhesion properties of the binder to keep the
cured product on the article to which it is applied and UV
cured.
[0102] Suitable combinations of acrylates include a first
ingredient selected from:
Ethoxylated (3) phenol monoacrylate such as Photomer 4039 from
Cognis; ethoxyethoxyethyl acrylate; bisphenol A epoxy diacrylate;
isobornyl acrylate; diacrylate such as Photomer 4127F from Cognis;
and 1,6-hexanediol diacrylate; and a second ingredient selected
from: N,N-dimethylacrylamide; and/or an acrylate polyester adhesion
promoter such as Craynor 131B or Craynor 704 from Cray Valley;
methylacrylamide; acidic mono and tri-acrylates such as SR9050,
SR9051 from Sartomer.
[0103] It has been found that it is desirable to select component
(b) from among acrylate functional oligomers. The nature of an
oligomer is well understood by those skilled in the art.
[0104] Again (particularly in combination with an acrylate monomer
as component (a)) selecting this material in this way gives
desirable cure properties to the UV curable binding material and
contributes to the viscosity which is desirable for maintaining
dispersion of the components in the composition. From among
suitable acrylate functional oligomers it has been found that epoxy
acrylate and urethane acrylate functional oligomers result in
desirable properties.
[0105] Specific examples of acrylate functional oligomers which may
be employed in the present invention include those given below as
epoxy acrylate or urethane acrylate materials and additionally
polyether acrylate such as Genomer 3497 from Cray Valley.
[0106] Suitable epoxy acrylate materials include:
bisphenol A epoxy acrylate such as Craynor 104 from Cray Valley or
Craynor 115 (Lower viscosity version of Craynor 104) from Cray
Valley; modified tetrafunctional epoxy acrylate such as Craynor 190
from Cray Valley. Suitable urethane acrylate materials include
aliphatic urethane materials and also resins prepared in accordance
with International Patent Publication No. WO 98/31655 and U.S. Pat.
No. 4,295,909 (Baccei); Flex Resin II and Acryflex from Henkel
Loctite; Genomer 1122 from Rohm AG; Ebecryl 230, 270, 3500, 8402
and 4842 from UCB/Radcure; and Craynor 965 from Cray Valley.
[0107] More particularly it has been found that where component (b)
comprises a combination of epoxy acrylate and urethane acrylate
functional oligomers, cure products with the types of desirable
properties set out above are achieved.
[0108] As with the other components of compositions of the present
invention it is desirable that component (c), the photoinitiator
component, may be chosen to have specific properties.
[0109] The photoinitiator can be selected from among: phosphine
oxides; hydroxyketones and moropholino compounds.
[0110] Suitable photoinitiators include:
diphenyl (2,4,6-trimethylbenzoyl)phosphine oxide;
1-hydroxycyclohexyl phenyl ketone;
bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide such as Irgacure
819 from BASF; 2,2'-dimethoxy-2-phenylacetophenone;
2-benzyl-2-(dimethylamino)-1-[4-(4-morpholinyl)phenyl]-1-butanone;
2-methyl-1-(4(methylthio)phenyl)-2-moropholino-1-propane;
bis(2,6-dimethoxybenzoyl)-2,4,4-trimethyl pentyl phosphine oxide;
and 1-hydroxy-cyclohexyl-phenyl-ketone (a blend of 25:75 of the
latter two components may be employed).
[0111] For example it is important to achieve good cure through
volume (CTV). It has been found that selection of certain
photoinitiators can improve the CTV achieved. Therefore it is
desirable that component (c) comprises a component which enhances
depth of cure. Without such a depth of cure the product may remain
partially uncured on a threaded article to which it is applied,
which is undesirable. Suitable photoinitiators which achieve this
effect include photoinitiators with phosphine oxide functionality
such as diphenyl (2,4,6-trimethylbenzoyl)phosphine oxide;
bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide and
bis(2,6-dimethoxybenzoyl)-2,4,4-trimethyl pentyl phosphine oxide.
Photoinitiators with phosphine oxide functionality have also been
found not to impart a yellow colour which may be imparted by other
photoinitiators. Such photoinitiators can be considered
"non-yellowing".
[0112] Another important factor in achieving a dry (tack-free)
product is achieving sufficient surface cure of the composition.
Without sufficient surface cure of the composition it will remain
wet/tacky to touch. It has been found that selection of certain
photoinitiators can improve the surface cure achieved. Therefore it
is desirable that component (c), the photoinitiator component,
includes a component which enhances surface cure is also desirable
to achieve a suitable end product. Suitable photoinitiators which
achieve this effect include: hydroxy ketones, e.g., .alpha.-hydroxy
ketones. Specific photoinitiators that may be used include:
1-hydroxycyclohexyl phenyl ketone;
2,2'-dimethoxy-2-phenylacetophenone;
2-benzyl-2-(dimethylamino)-1-[4-(4-morpholinyl)phenyl]-1-butanone;
and 4-hydroxycyclohexyl phenyl ketone.
[0113] Utilising a combination of (i) a component which enhances
depth of cure, and (ii) a component which enhances surface cure as
a photoinitiator is particularly useful. In this respect it has
been found that utilising a combination of a photoinitiator with
phosphine oxide functionality and a photoinitiator with hydroxy
ketone functionality is desirable. Typical ratios of use are 20:80
to 30:70 such as 25:75 respectively.
[0114] The thickener component also plays a part in the
compositions of the present invention. In particular it is
desirable to include a thickener component to thicken the uncured
formulation which is usually liquid. The thickening of the
composition imparts sufficient viscosity to the composition so that
it has the physical properties to allow and maintain the dispersion
of the other components in the composition, in particular prior to
UV cure. In particular it is desirable that the microcapsules
remain dispersed throughout the composition. If the composition was
not sufficiently viscous the settling out of components may occur.
This might result in the first cure reaction not sufficiently
curing the binder composition throughout its mass. Secondly the
components of the second cure mechanism, in particular the
microencapsulated epoxy component, may become localised in one part
of the composition (for example at the bottom of a mass thereof)
and when the UV cure takes place the binder does not contain an
even distribution of the components of the second cure mechanism.
Accordingly, subsequent rupture of the microcapsules and reaction
thereof with the amine may not result in a desired bond strength
between threaded components.
[0115] The thickener component [component (d)] may be selected from
organic thickener materials such as waxes and polymeric thickeners
and also inorganic thickener materials such as silica.
[0116] Suitable organic materials include:
polymethyl methacrylate (PMMA) granules; polyethylene materials;
fluoropolymers including polytetrafluoroethylene (Teflon.TM.)
materials; nylon materials; and co-polymer materials such as
methyl/n-butyl methacrylate copolymer. Any of the foregoing may be
provided in powder form.
[0117] Gums such as xanthum gum (also polymeric) may be utilised
also.
[0118] Silica has been found to be a very useful thickener
component in accordance with the present invention. It achieves the
necessary thickening of the composition without interfering to any
substantial extent with the first or second cure mechanisms.
[0119] Suitable silicas, such as fused silicas, may be untreated or
treated so as to alter the chemical nature of their surface.
Virtually any reinforcing fused silica may be used.
[0120] Particularly desirable silicas have a low ion concentration
and are relatively small in particle size (e.g., on the order of
about 12 .mu.m, with a median of up to about 30 .mu.m and as low as
less than about 2 .mu.m), such as the Silbond materials,
commercially available under the tradename Aerosil 200, supplied by
Degussa.
[0121] Other materials may be added as (inorganic) thickener
components and include those constructed of or containing aluminum
oxide, silicon nitride, aluminum nitride, silica-coated aluminum
nitride and micronized quartz, provided they are not basic in
nature.
[0122] Desirably, component (e) may be a tertiary amine. Tertiary
amines have in particular been found to have a suitable rate of
cure were used in combination with the epoxy material released from
the microencapsulated epoxy materials of the present invention.
Tertiary amines are also likely to provide a better shelf life for
compositions containing acrylate monomers than would be the case
with primary or secondary amines. Included within the scope of the
invention are amines where the nitrogen atom forms part of a
heterocyclic group such as a substituted or unsubstituted pyridine
group. Those tertiary amines which are useful in the present
invention include hindered tertiary amines. Of hindered tertiary
amines which are useful, the subgroup of hindered aromatic tertiary
amines are of note. Specific amines useful in the present invention
include: 1,3-di-(4-pyridyl)propane(dipyr); modified polyamine such
as Ancamine K54 from Air Products; primary amine such as
4,4'-diaminodicyclohexylmethane; secondary amine such as
1,3-di-4-piperidylpropane; biaryl containing amine substituents
such as Kayahard A-A or Kayahard A-B from Nippon Kayaku. Dipyr is a
very effective material in this respect. The subgroup of hindered
tertiary biaryl amines are of note.
[0123] Component (f), the epoxy material, which is
microencapsulated includes many common epoxy resins, such as those
having monofunctionality and multifunctionality (for example those
having two or more epoxy groups per molecule). Examples of such
epoxy resins with monofunctionality include C.sub.4-C.sub.28 alkyl
glycidyl ethers; C.sub.2-C.sub.28 alkyl- and alkenyl-glycidyl
esters; C.sub.1-C.sub.28 alkyl- and mono-phenol glycidyl ethers.
Examples of such epoxy resins with multifunctionality include
poly-phenol glycidyl ethers; cycloaliphatic epoxy resins;
polyglycidyl ethers of pyrocatechol, resorcinol, hydroquinone,
4,4'-dihydroxydiphenyl methane (or bisphenol F),
4,4'-dihydroxy-3,3'-dimethyldiphenyl methane,
4,4'-dihydroxydiphenyl dimethyl methane (or bisphenol A),
4,4'-dihydroxydiphenyl methyl methane, 4,4'-dihydroxydiphenyl
cyclohexane, 4,4'-dihydroxy-3,3'-dimethyldiphenyl propane,
4,4'-dihydroxydiphenyl sulfone, and tris(4-hydroxyphyenyl)methane;
polyglycidyl ethers of the chlorination and bromination products of
the above-mentioned diphenols; polyglycidyl ethers of novolacs;
polyglycidyl ethers of diphenols obtained by esterifying ethers of
diphenols obtained by esterifying salts of an aromatic
hydrocarboxylic acid with a dihaloalkane or dihalogen dialkyl
ether; polyglycidyl ethers of polyphenols obtained by condensing
phenols and long-chain halogen paraffins containing at least two
halogen atoms; phenol novolac epoxy resins; cresol novolac epoxy
resins; and combinations thereof.
[0124] Among the commercially available epoxy resins suitable for
use herein are polyglycidyl derivatives of phenolic compounds, such
as those available under the trade names EPON 828, EPON 1001, EPON
1009, and EPON 1031, from Shell Chemical Co.; DER 331, DER 332, DER
334, and DER 542 from Dow Chemical Co.; GY285 from Ciba Specialty
Chemicals; and BREN-S from Nippon Kayaku, Japan. Other suitable
epoxy resins include polyepoxides prepared from polyols and the
like and polyglycidyl derivatives of phenol-formaldehyde novolacs,
the latter of which are available commercially under the trade
names DEN 431, DEN 438, and DEN 439 from Dow Chemical Company.
Cresol analogs are also available commercially under the trade
names ECN 1235, ECN 1273, and ECN 1299 from Ciba Specialty
Chemicals. The cycloaliphatic epoxy resin, UCB CAT-002, available
commercially from UCB, is desirable as well. SU-8 is a bisphenol
A-type epoxy novolac available from Shell Chemicals (formerly,
Interez, Inc.). In addition, UVR-6105 and 6110 (each
3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxylate) and
UVR-6128 [(bis-(3,4-epoxycyclohexyl)adipate], each available
commercially from UCB Chemicals, are desirable for use herein, with
the latter being particularly desirable. And of course combinations
of the different epoxy resins are also desirable for use
herein.
[0125] The capsule itself is desirably a double walled capsule. An
example of a double walled capsule is one including walls
constructed of gelatin and/or polyoxymethylene urea (PMU).
[0126] Desirably the concentration of epoxy resin component within
the capsule is between 40 and 100%, more typically 50 to 80%,
suitably 50 to 70% for example 50 to 60% (weight/weight).
[0127] In any event to ensure good cure, particularly of the second
cure mechanism desirably the amount of epoxy which is introduced
with the microcapsules and which is not internally held in the
microcapsules prior to their rupture by screw threading is
desirably less than about 0.5% by weight of the total composition.
Epoxy may be carried externally with the microcapsules or may be
released on premature rupture of the microcapsules. This means that
the second cure mechanism reaction will be substantially
unaffected.
[0128] It has been found that the mean diameter of the
microcapsules is desirably in the range of from about 100 .mu.n to
about 140 .mu.m though it will be appreciated that individual
capsules may have a diameter well outside these mean ranges. For
example individual microcapsules can have a diameter in the range
of from about 50 .mu.m to 200 .mu.m. Suitably the mean diameter is
in the range from about 110 .mu.m to about 130 .mu.m. Typically the
mean diameter will be about 120 .mu.m.
[0129] A further component which is suitable for use in
compositions of the present invention is a plasticiser component.
While many plasticiser components may be utilised, it is desirable
that the plasticiser is a polymeric one such as PMMA. Other
plasticisers may also be included in the inventive composition
examples of which include those available commercially from Union
Carbide, such as under the trade designations TONE Polyol 301 and
310. Other suitable plasticiser components include expandable
plastic such as those sold under the trade name EXPANCEL. According
to information from the website http://www.expancel.com/, EXPANCEL
is a registered trade-mark for microspheres which are small
spherical plastic particles. The microspheres consist of a polymer
shell encapsulating a gas. When the gas inside the shell is heated,
it increases its pressure and the thermoplastic shell softens,
resulting in a dramatic increase in the volume of the microspheres
(by a factor of 40). The specific material which can be used is DE
80 or DE 30. It is useful that compositions of the present
invention can have a colour imparted thereto. Usually, pigments can
be added to the compositions of the present invention without any
substantive interference in the first or second cure mechanisms. It
is useful to impart a colour to compositions of the present
invention, as the colour can be used as a product indicator in many
ways, usually to allow for ease or recognition, for example, to
indicate a particular size of bolt or nut, the customer to whom the
threaded article with the pre-applied product should be
delivered.
[0130] Suitable pigment components include coloured metal complexes
for example Fe and Co complexes. Specific examples include:
Rocket Red T-13 (organic pigment based on a thermoset resin matrix
including an Fe complex material available from Dayglo Color Corp);
also Laser Red 2 and Laser Red 3 with similar chemistry and
available from Sterling; Cobalt aluminate complexes such as the
product PK5091 from Ferro B.V. and Comet Blue 3 from Swada (both
Cobalt aluminate blue spinel materials); V-9248 Blue (Cobalt
chromite blue-green spinel from Ferro B.V.); F-5686 Turquoise
(Cobalt chromite blue-green spinel Co(Al,Cr).sub.2O.sub.4:MgO:ZnO
from Ferro B.V.).
[0131] In general Fe complexes impart a red colour whereas Co
complexes impart a blue colour. It is unusual to be able to colour
materials which are to be cured by UV light with a blue pigment as
a blue pigment normally interferes to a substantial extent with the
cure process by absorbing UV light.
[0132] Suitable amounts for the components of the UV binder part of
the composition based on weight by weight percentage based on that
part of the composition excluding the microencapsulate epoxy
component (i.e., the composition excluding the microcapsules being
taken as 100% of the weight) may be selected independently of one
another as follows:
[0133] (meth)acrylate functional monomer, 25 to 45% more typically
30 to 42% suitably 32 to 40% for example 33 to 38%;
[0134] (meth)acrylate functional oligomer, 35 to 55% more typically
39 to 52% suitably 41 to 50% for example 43 to 48%;
[0135] photoinitiator, up to 15%; more typically 1 to 12% suitably
3 to 10% for example 5 to 8%;
[0136] thickener, up to 14% more typically 1 to 11% suitably 2 to
9% for example 4 to 7%; and
[0137] amine, 2 to 14% more typically 4 to 14% suitably 6 to 12%
for example 8 to 10%. Suitable combinations are disclosed
above,
where component (a) comprises a combination of (meth)acrylate
functional monomers: one of the monomers is typically present in
the range of 15 to 29%, more typically 17 to 27%, suitably 19 to
25%, for example 21 to 23%, whilst a second monomer is typically
present in the range of 7 to 21%, more typically 9 to 19%, suitably
11 to 17%, for example 13 to 15%;
[0138] where component (b) comprises a combination of
(meth)acrylate oligomers: one of the oligomers is typically present
in the range of 22 to 38%, more typically 24 to 36%, suitably 26 to
34%, for example 28 to 32%, whilst a second oligomer is typically
present in the range of 7 to 22%, more typically 9 to 20%, suitably
11 to 18%, for example 13 to 16%;
[0139] where component (c) comprises a combination of
photoinitiators: one of the photoinitiators is typically present in
the range of 0.2 to 9%, more typically 0.4 to 7%, suitably 0.6 to
5%, for example 0.8 to 3%, whilst a second photoinitiator is
typically present in the range of 1 to 12%, more typically 2 to
10%, suitably 3 to 8%, for example 4 to 6%; and
[0140] where component (d) comprises a combination of thickeners:
one of the thickeners is typically present in the range of 0.5 to
10%, more typically 1 to 8%, suitably 2 to 6%, for example 3 to 4%,
whilst a second thickener is typically present in the range of 0.2
to 9%, more typically 0.5 to 7%, suitably 0.7 to 5%, for example
0.9 to 3%.
[0141] As already stated ranges are based on weight by weight
percentage based on that part of the composition excluding the
microencapsulate epoxy component (i.e., the composition excluding
the microcapsules being taken as 100% of the weight).
[0142] In particular the compositions of the invention are
generally made up by preparing the UV curable binder portion
thereof and the amine and then dispersing within that composition
the required amount of microencapsulated epoxy component. For
convenience therefore we will refer to the ratio of the "binder
composition" or "acrylate portion" as that part of the composition
including all of the components other than the microcapsules and
the "microcapsule portion" as referring to the amount of the
microcapsules.
[0143] Generally the ratio of mixing by weight of the binder
composition to the microcapsule portion is 50-70:30-50. The ratio
of each will be selected so that the combined ratios add to
100.
[0144] Typically the plasticiser component will be present in an
amount of less than 3% by weight of the total composition.
[0145] Typically the pigment may be present in an amount from about
0.1 to about 0.5% by weight of the total composition, such as from
about 0.2 to about 0.4%, for example from about 0.25 to about
0.35%.
[0146] The inventive composition can be stored for use as either a
one-part or a two-part composition. When formulated as a two-part
composition, the first part of the composition may comprise; [0147]
(i) a (meth)acrylate functional monomer, [0148] (ii) a
(meth)acrylate functional oligomer, [0149] (iii) a photoinitiator,
[0150] (iv) a thickener, [0151] (v) an amine, and optionally
additionally one or both of; [0152] (i) a plasticiser [0153] (ii) a
pigment component. whilst the second part of the composition will
usually comprise the encapsulated epoxy resin.
[0154] A composition stored as a one-part composition has a shelf
life of at least one week. Whereas a composition stored as a
two-part composition, the first part of the composition has a shelf
life of at least 6 months at 5.degree. C., and the second part has
an indefinite shelf life. When the two-part composition is mixed
prior to use, the resulting composition has a shelf life of at
least one week.
[0155] Subsequent to the first stage cure of the composition, the
chemistry of the composition can confer reduced "peel off" of the
composition on a threaded bolt following the second stage cure,
depending upon the design of the bolt/nut joint.
[0156] The invention extends to apparatus substantially as
described herein with reference to and/or as illustrated in the
accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0157] FIG. 1 is a schematic representation of an apparatus
according to the present invention;
[0158] FIG. 2 is a side elevation showing a more detailed
construction of an apparatus of the present invention;
[0159] FIG. 3 is an end part sectional view of the apparatus of
FIG. 2 (from the left end thereof);
[0160] FIG. 4 is an enlarged partial view similar to that of FIG.
3;
[0161] FIG. 5 shows a cross-sectional view of an eccentric rotor
pump for use in a feed supply system/apparatus of the
invention;
[0162] FIGS. 6A and 6B respectively show: applicator (coating
block) temperature plotted against coating efficiency; and coating
efficiency plotted against (fastener) bolt temperature; and
[0163] FIGS. 7A and 7B show a picture of a bolt with composition
applied thereto; FIG. 7A showing an excess of applied product and
FIG. 7B showing a desirable amount of applied product.
DETAILED DESCRIPTION OF THE INVENTION
[0164] FIG. 1 shows a schematic representation of an apparatus
according the present invention. The apparatus is for the
application to fasteners of a curable composition. The two-stage
composition is desirably a one-part composition having at least two
cure stages. The advantage of using a one-part composition is that
application of the composition can take place in one step. If the
composition is a two-part composition then application of the
two-parts of the composition normally takes place separately as
mixing of the two-parts of the composition will cause the
composition to cure.
[0165] The apparatus 1 has a conveyor for conveying fasteners 2 to
an application station which in the embodiment is a coating block
5. A first conveyor is provided which includes an endless belt 3
(in FIG. 1 only part of the belt is shown), which conveys the
fasteners or bolts to the coating block 5. It will be noted that
the endless belt 3 picks up the fasteners 2 and conveys them
through the application station. The conveyor 3 extends through the
application station (passing across the coating block 5).
[0166] The coating block 5 is a component of the apparatus that is
replaceable and different sizes of coating blocks can be used to
achieve different amounts of applied product on the fasteners. With
reference to FIGS. 2-4 also provided is a second conveyor in the
form of an endless belt 8 which is for conveying fasteners 2 to an
irradiation station which in the embodiment is a focused UV light
assembly 10. In particular the assembly 10 has a UV emitting light
11 housed in a closed housing 12 (in FIG. 1 the housing is shown in
part cut-away to show the internal UV light). An elongate aperture
13 is formed in the base of the housing 12, which allows a narrow
band of UV light to escape from the housing 12. A cover (such as a
sliding cover) may be provided over the slot. The narrow band of UV
light is arranged to be coincident with a coating layer of applied
composition 9 on the fasteners.
[0167] The coating layer of applied composition 9 is achieved by
rotating the fasteners across the coating block 5. In particular
the coating block 5 has a contact portion for contacting the
composition with the fastener. The contact portion is provided in
the form of an application surface 14 (on coating block 5) onto
which the two-stage curable composition is dispensed. In the
embodiment shown, beads 6 of the (liquid) composition are dispensed
onto the application surface 14 from the underside of the coating
block 5. This may be achieved by providing apertures in the coating
block which open onto the application surface 14 and for example
using a conventional dispensing system such as an air-pressurised
line 55 which feeds product to an eccentric rotor pump 53 which in
turn supplies product to the coating block 5 (best seen from FIG.
4). The apparatus 1 also has a rail 4 (see also FIGS. 3 and 4),
which supports the fastener close to one end of the fastener (the
end closest the head). The fasteners 2 are gripped between the belt
3 and the rail 4 sufficiently well so that movement of the belt 3
in the direction of the arrow 16 (left to right in the orientation
shown in FIGS. 1 and 2) results in the bolt moving in the direction
of the arrow 16 all the while rotating (rolling) as indicated by
arrow 17.
[0168] In the embodiment the coating block 5 forms (part of) a
second rail which also supports the fastener 2. Movement of the
belt 3 thus causes the fasteners 2 to rotate across rail 4 and
application surface 14 of the coating block causing each fastener
to roll through the product 6 thus creating a coating layer 9 of
applied composition. It will be appreciated that rotation of the
fastener is about a longitudinal axis thereof.
[0169] As shown in FIG. 3 the coating block is temperature
controlled by a temperature control element 52 which can be used to
raise and lower the temperature of the coating block (in particular
an applicator surface thereof). The element 52 is located in a bore
within the coating block.
[0170] The fasteners continue to rotate (again about a longitudinal
axis) while passing under the irradiation assembly 10 (rotation
being effected by the second conveyor 8). The emitted UV light
(radiation) from the assembly 10 is arranged to irradiate the
coating layers 9 of product so as to cure the composition so that
it is dry to touch. The apparatus further comprises a feed--in
means (fastener feeder) 15 which will, together with the remainder
of the apparatus, be described in more detail with reference to
FIGS. 2-4.
[0171] The apparatus of the invention sits on a support structure,
which has been labelled 20. The apparatus has a fastener feeder 15
for feeding fasteners one by one to the first conveyor belt tray.
As seen in FIG. 2 an air blower 51 is provided for blowing air of a
temperature selected for the fasteners. In particular the air
blower 51 is of the type usually described as an air knife blower.
The blower 51 is arranged to heat at least that portion of the
fasteners to which the composition will be applied as they pass
through the fastener feeder 15.
[0172] As can been seen from FIG. 2 the belt 3 runs in a series of
pulley wheels 22 arranged in line. The belt 3 is driven by a
motorised pulley wheel 23. An adjustable (tensioning) pulley wheel
24 is provided which can be used to tension the belt 3 as
appropriate. All of the pulley wheels are supported on an
adjustable support frame 21.
[0173] In particular an adjusting mechanism is provided which is
operated by rotation of a band wheel 25. In particular the relative
distance between the belt 3 and the support 20 can be adjusted to
accommodate different sizes of bolts. In particular the distance
between the belt 3 and the support rail 4 (see FIGS. 1 and 3-4) can
be adjusted so that different sizes of fasteners can be
accommodated between the belt and the support rail 4. As described
with reference to FIG. 1 the coating block 5 is also provided for
application of composition to at least a portion of each of the
fasteners 2.
[0174] The belt 8 works in an analogous fashion running across
pulley wheels 26 and been driven by a motorised pulley wheel 27 and
tensioned by a further tensioning wheel 28. The belt 8 and its
associated pulley wheels 26-28 are all mounted on an adjustable
support 30 which can be adjusted by turning handwheel 29 to alter
the vertical distance between the belt 8 and the guide rail 4 (and
the second rail 31).
[0175] If the fasteners have sufficient momentum, no additional
mechanism may be needed to effect transfer of the fasteners from
belt 3 to belt 8, as at least certain fasteners may continue to
roll along between exiting from belt 3 and before being picked up
by belt 8. However it is desirable (especially for smaller
fasteners) to provide a transfer mechanism between the two
belts.
[0176] In the embodiment shown in FIG. 2 the last pulley wheel 37
(last in the direction left to right) and the first pulley wheel 33
(again first in the same direction) have arranged between them a
transfer belt 32. The transfer belt 32 does not run directly
between pulley wheels 37 and 33. This is because belts 3 and 8 run
at different speeds. It is only necessary that the transfer belt 32
is driven at one end and runs on a (free wheeling) separate pulley
on the other. In the embodiment the belt 32 turns with the aid of
pulley wheel 37 while it free wheels on a separate pulley wheel at
its other end (proximate first pulley wheel 26, i.e., wheel 33). As
best seen from FIG. 3 the pulley wheel 37 is double grooved having
grooves 38 and 39 in which the belts 3 and 32 respectively run. The
transfer belt 32 ensures smooth transition of smaller pieces
between the two larger belts 3 and 8.
[0177] As described with reference to FIG. 1 light assembly 10 is
provided to shine UV light on the applied product as discussed.
[0178] It will be appreciated that the bolts are continually
rotated on a longitudinal axis when passing through the machine.
Furthermore the fasteners are in a generally horizontal position.
This is advantageous as the light source can be placed above the
fastener rather than along side it or beneath it so that it is less
likely that product would come off the fasteners 2 and land on the
lamp assembly 10. Fasteners exiting the apparatus have been
labelled 34 for convenience.
[0179] FIGS. 3 and 4 show a more detailed view, which is part
sectional. In the view of FIGS. 3 and 4 the fastener feeder 15 has
been omitted for the purposes of clarity. As can be seen clearly
from these Figures the support 21 can be moved vertically relative
to the rails 4 and 31 (which in turn moves the pulley wheels 22-24
and 37 as described previously) by virtue of an adjusting mechanism
40 which is operated by the rotation of handwheel 25. In the view
shown in FIGS. 3-4 the rail 31 does not appear as the view has been
taken where the coating block 5 forms part of the second rail.
[0180] It will be noted from FIGS. 3 and 4 that a guide is provided
each side of the fastener to keep the fastener on the rails 4,31
through the entire apparatus. In particular a first guide 43 and a
second guide 44 guide the fastener along its travel path. In
particular the first guide 43 is in the form of an abutment plate
against which the head 45 of the fastener abuts. The second guide
44 is also in the form on abutment plate against which the stem 46
of the fastener abuts. The guides 43,44 maintain the fastener on
its path by preventing any substantial movement of the fasteners
transversely across the rails.
[0181] It will be noted that the spacing between the rail 4 and the
guide 43 is such that they form stops on opposing sides of the head
(i.e. arranged to abut the top side and the underside of the head
of the fastener) thus preventing the fasteners from moving off line
to any great extent (by restricting movement of the head). The rail
4 and the guide 43 assist in preventing the fasteners arranging
themselves in a diagonal direction across the rails.
[0182] All of support 21 and the pulleys belts etc. are supported
by the adjustment mechanism 40 and movement thereof allows the
relative vertical distance between the rails 4 and 31 and in
particular the belt 3 to be adjusted.
[0183] Six rods 41, 42, 47-50 (see FIG. 2) arranged substantially
horizontally and vertically spaced apart form part of an adjustment
mechanism which is arranged to allow for adjustment of the
apparatus to accommodate differently sized fasteners 2 (in
particular those of greater length). Only two of the rods 41 and 42
are shown in view of FIG. 3. In particular a slide mechanism
operates along rods 41,42 to allow adjustment of the apparatus in
an essentially horizontal direction. In particular a clamp or lock
35 can be released which allows for the substantially horizontal
movement of support 21 and all of its associated components
together with the coating block 5, (block 5 moves on support 36)
rail 31 and guide 44 to be moved closer or further away from the
remainder of the apparatus (for example rail 4). This allows for in
particular longer fasteners to be coated using the apparatus of the
invention.
[0184] The rail 4 and the first guide 43 are adjustable relative to
each other so that the distance between them can be selected
allowing for use of the apparatus with fasteners having differently
sized heads.
[0185] An enlarged end view of part of the apparatus shown in FIG.
2 can be seen in FIG. 4. Additionally shown in FIG. 4 is a
reservoir 54 which together with an air-pressurised line feeds
composition held in the reservoir to the eccentric rotor pump 53.
The eccentric rotor pump is connected directly to the coating block
5 by a rigid connection to reduce losses in control of the amount
being dispensed by length and/or flexing of the conduit.
[0186] More detail of the eccentric rotor pump 53 is shown in FIG.
5, which gives a cross-sectional view of a suitable pump. The
eccentric rotor pump 53 has a pump housing 102 with a rotor 108,
which is mounted on a driven assembly 107. The rotor is connected
to helical pump elements 105, which are arranged in a general
double helix arrangement within a stator 104. Driving of the rotor
108 also rotates elements 105 and causing a pumping action toward
the outlet end 110 of the pump 53.
[0187] The process is carried out as follows:
[0188] The fasteners are fed into the first conveyor by a fastener
feeder;
[0189] The conveyor conveys the bolts across an applicator which
applies product to the bolts, the bolts are then transferred to a
second conveyor which runs at a different (slower) speed;
[0190] The second conveyor conveys the bolts past the UV light
source for curing of the product applied in the application
station. By the time the bolts leave the second conveyor (see for
example the bolts labelled 34 in FIG. 2) they are dry to touch.
EXAMPLES
[0191] Separate bolts having applied thereto (by an apparatus of
the invention as shown in the Figures) a composition according to
Example 1 below are shown in FIGS. 7A and 7B. FIG. 7A shows a bolt
having a greater than optimal amount of product thereon. As
described above and as set out in greater detail below, the amount
of product on the bolt which is applied by the apparatus can be
controlled so as to provide a desirable (optimal) amount of product
such as in FIG. 7B. One of the main controls for the amount of
applied product picked up by an article from the applicator is
temperature. Working within a selected temperature difference range
between the applicator temperature and the article temperature will
allow a person skilled in the art to apply product in desired
amounts such as is shown in FIG. 7B.
Coating Efficiency Tests Effect of Bolt and Coating Block
Temperatures
[0192] This test examined (a) (article) bolt temperature and (b)
(applicator) coating block temperature effects on the coating
efficiency. The test trials were carried out utilising an apparatus
as shown in the drawings and utilising a composition as set out in
Example 1 below.
(a) Bolt Temperature Effects
Description:
[0193] To examine how changes in bolt temperature affect the
coating efficiency, the following settings were kept constant (on
the apparatus as shown in the drawings --FIGS. 2-4): bolt feed
rate, coating block temperature (30.degree. C.) (conveyor in the
applicator station) belt speed and pump speed.
[0194] Bolts were preheated to each of temperatures 35.degree. C.,
45.degree. C. and 55.degree. C. Samples from each temperature were
run through the coating machine and coating weight was calculated
for each temperature by weighing a number of samples from each
run.
[0195] Product not coated onto the bolt was wasted over either the
side or the end of the coating bar. The coating efficiency (%) is
calculated as follows: (Amount of product coated onto the
bolt/amount of product pumped on to the coating bar per
bolt).times.100.
Results
[0196] FIG. 6A shows the coating efficiency with varying bolt
temperature. More specifically, FIG. 6A shows that an increase in
temperature of 20.degree. C. gives a decrease in coating efficiency
of 8%, and that preheating bolts to a temperature in the range of
30-40.degree. may give an optimal coating efficiency. Using
pre-heated bolts also was observed to provide a homogenous coating
layer.
(b) Coating Block Temperature Effects
Description:
[0197] To examine coating block temperature effects the bolt
temperature was set to 40.degree. C., and the coating bar was run
with the following temperatures 25.6.degree. C., 27.5.degree. C.,
30.degree. C., 32.5.degree. C. 35.degree. C. The rest of the
settings were kept as before. The following graph shows average
amount of product picked up per bolt with varying bar
temperature.
Results:
[0198] FIG. 6B shows the coating efficiency with varying coating
block temperature (coating block temperature controlled as
described above). In this case we see that by raising the coating
block (bar) temperature from 26.degree. C. to 35.degree. C.
increases the coating efficiency by 7.5%.
[0199] As bolt temperature increases, coating weight and coating
efficiency decreases. As the temperature of the coating block
increases, coating weight and coating efficiency also increase. As
all runs produced good quality coatings (as exemplified in FIG.
7B), both bolt and coating block temperature can be used to control
the coating efficiency of the system.
UV Acrylate/Epoxy Threadlocking Compositions
[0200] A threadlocking formulation according to the invention was
made with the components in the table below. The encapsulated epoxy
resin was the last component added to the formulation. The epoxy
resin was EPON 828, a difunctional bisphenol A/epichlorohydrin
derived liquid epoxy resin available from Resolution Performance
Products. It was encapsulated in double walled gelatine/PMU
capsules. Photomer 4039 is an ethoxylated (3) phenol monoacrylate
(available from Cognis). Ebecryl 3500 is an acrylate epoxy oligomer
(available from UCB/Radcure) used for speed of cure. Ebecryl 270 is
an aliphatic urethane acrylate oligomer (also available from
UCB/Radcure) used for enhancing flexibility. Flex Resin II
(available from Henkel Loctite) is used for enhancing flexibility.
The components other than the microencapsulated epoxy are given in
amounts based on w/w of the composition excluding the
microencapsulated epoxy. The part of the composition excluding the
epoxy microcapsules (hereinafter "acrylate portion") and the epoxy
microcapsules were combined in the following ratio by weight: 59.41
parts acrylate potion to 40.59 parts epoxy microcapsules. This
ratio is employed in all Examples.
Example 1
TABLE-US-00001 [0201] TABLE 1 % weight of components in the part of
the composition excluding the microencapsulate epoxy component
Component % weight Photomer 4039 21.53 N,N Dimethylacrylamide 13.78
Ebecryl 3500 30.14 Ebecryl 270 14.64 Diphenyl
(2,4,6-trimethylbenzoyl) phosphine oxide 1.73 1-Hydroxycyclohexyl
phenyl ketone 4.3 Polymethyl methacrylate granules (PMMA) 1.96
Silica 3.3 Dipyr 8.62
[0202] The viscocity of this composition excluding the
microencapsulated epoxy component, when measured with a Haake Roto
Visco 1, c60/1.degree. Cone, shear rate 244 s.sup.-1, was 1,326
mPas.
Example 2
TABLE-US-00002 [0203] TABLE 2 % weight of components in the part of
the composition excluding the microencapsulate epoxy component
Component % weight Photomer 4039 21.96 N,N Dimethylacrylamide 14.06
Ebecryl 3500 30.74 Flex Resin II 14.93 Diphenyl
(2,4,6-trimethylbenzoyl) phosphine oxide 1.76 1-Hydroxycyclohexyl
phenyl ketone 4.39 Silica 3.37 Dipyr 8.79
[0204] The viscocity of this composition excluding the
microencapsulated epoxy component, when measured as in Example 1,
was 731 mPas.
Application of Product
[0205] A composition according to each of the Examples above
(including the microencapsulated epoxy component) was applied to
threaded bolts. The composition was irradiated for 3 to 4 seconds
at an intensity of 60 mW/cm.sup.2 provided by a medium pressure
iron doped mercury vapour lamp. Irradiation of coated parts left a
dry to touch coating.
[0206] A composition according to each of the Examples above has a
shelf life of at least 6 months at 5.degree. C. The
microencapsulated epoxy component has an indefinite shelf life. A
composition according to the Examples above including the
microencapsulated epoxy component has a shelf life of at least one
week. The composition can be stored for use in either a one-part or
a two-part format. When formulated as a two-part composition, one
part of the composition may comprise a composition according to
each of the Examples above and a second part will usually contain
the microencapsulated epoxy component.
[0207] Threaded bolts which have had a composition according to the
Examples above including the microencapsulate epoxy component
applied to them and UV cured have a shelf life of at least one
year. Break/prevail values in the region of 20 Nm have been
recorded from assemblies of M10 mild steel black oxide bolts and
M10 mild steel nuts following a 72 hour cure of the composition
according to each of the Examples above (including the
microencapsulated epoxy component) at room temperature.
[0208] It is appreciated that certain features of the invention,
which are, for clarity, described in the context of separate
embodiments, may also be provided in combination in a single
embodiment. Conversely, various features of the invention which
are, for brevity, described in the context of a single embodiment,
may also be provided separately or in any suitable
subcombination.
[0209] The words "comprises/comprising" and the words
"having/including" when used herein with reference to the present
invention are used to specify the presence of stated features,
integers, steps or components but does not preclude the presence or
addition of one or more other features, integers, steps, components
or groups thereof.
* * * * *
References