U.S. patent number RE36,177 [Application Number 08/410,082] was granted by the patent office on 1999-04-06 for method of packaging an adhesive composition and corresponding packaged article.
This patent grant is currently assigned to H. B. Fuller Licensing & Financing, Inc.. Invention is credited to Emmanuelle Pariente, Alain Rouyer, Harald Werenicz, Peter Yeboa-Kodie.
United States Patent |
RE36,177 |
Rouyer , et al. |
April 6, 1999 |
Method of packaging an adhesive composition and corresponding
packaged article
Abstract
The invention relates to a method of packaging an adhesive
composition, especially a thermoplastic or thermosetting hot melt
adhesive. The method comprises the steps of providing one
substantially uniform separate portion of the adhesive composition;
sufficiently solidifying said portion for packaging; substantially
completely surrounding said sufficiently solidified portion with a
plastics packaging material. The packaging material being meltable
together with the adhesive composition and blendable into said
molten adhesive composition, the kind and amount of said packaging
material being chosen so as not to disadvantageously affect the
properties of the adhesive composition when blended into same.
Preferably, the packaging material is a net, a wrap, a sack or a
bag. Packagings made of plastic film are advantageously voided of
air, to prevent problems in melting. The packaged adhesive can be
melted as it is.
Inventors: |
Rouyer; Alain (Fresne Le Plan,
FR), Pariente; Emmanuelle (Bordeaux, FR),
Yeboa-Kodie; Peter (Scharnebeck, DE), Werenicz;
Harald (Reppenstedt, DE) |
Assignee: |
H. B. Fuller Licensing &
Financing, Inc. (N/A)
|
Family
ID: |
8165507 |
Appl.
No.: |
08/410,082 |
Filed: |
March 24, 1995 |
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
738176 |
Jul 30, 1991 |
|
|
|
Reissue of: |
017962 |
Feb 12, 1993 |
05257491 |
Nov 2, 1993 |
|
|
Current U.S.
Class: |
53/428; 53/436;
53/440; 53/443; 53/461; 53/473; 206/447 |
Current CPC
Class: |
C09J
175/04 (20130101); C08K 5/42 (20130101); C08K
5/10 (20130101); B65B 63/08 (20130101); B65D
65/466 (20130101); B29B 13/022 (20130101); C08K
5/10 (20130101); C08L 67/04 (20130101); C08K
5/42 (20130101); C08L 67/04 (20130101); B29K
2105/0097 (20130101) |
Current International
Class: |
B65D
65/46 (20060101); C08K 5/00 (20060101); C08K
5/10 (20060101); C08K 5/42 (20060101); B65B
005/06 (); B65B 063/00 () |
Field of
Search: |
;53/122,428,435,436,440,443,469,473
;206/447,524.1,524.3,524.4,524.7 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
0 115 307 |
|
Aug 1984 |
|
EP |
|
0 125 126 |
|
Nov 1984 |
|
EP |
|
0 469 564 |
|
Feb 1992 |
|
EP |
|
2 000 139 |
|
Aug 1969 |
|
FR |
|
22 48 046 |
|
Apr 1974 |
|
DE |
|
32 34 065 |
|
Apr 1983 |
|
DE |
|
31 38 222 |
|
May 1983 |
|
DE |
|
33 27 289 |
|
Feb 1985 |
|
DE |
|
86 28 513.0 |
|
Jan 1987 |
|
DE |
|
87 10 132.7 |
|
Oct 1987 |
|
DE |
|
36 25 358 |
|
Feb 1988 |
|
DE |
|
53-90324 |
|
Aug 1978 |
|
JP |
|
567360 |
|
Feb 1945 |
|
GB |
|
2132164 |
|
Jul 1984 |
|
GB |
|
2 156 302 |
|
Oct 1985 |
|
GB |
|
Other References
France 2,544,654; translation, Oct. 1984. .
"Pack Free" For Pressure Sensitive Hot Melt Adhesives, Surepack
Ltd., product literature. .
Swiss Patent 431,777, Translation. .
Derwent's Abstract, No. 92-44437/06, week 9206, Abstract of JP, A1,
3287683 (Tokiwa Kogyo KK), 18 Dec. 1991. .
"Verpackungs-alternative fur Haftschmelz-klebstoffe", Allgemeiner
Vliesstoff-Report Mar. 1992, Aus den Unternehmen [Translated as
Alternative Packaging for Hot melt Pressure-Sensitive Adhesive,
General Report on Non-Woven Fabrics Mar. 1992--News from the
Company..
|
Primary Examiner: Johnson; Linda
Attorney, Agent or Firm: Quan; Nancy N. Fischer; Carolyn
A.
Parent Case Text
This is a continuation, of application Ser. No. 07/738,176, filed
Jul. 30, 1991, which was abandoned upon the filing hereof.
Claims
We claim:
1. A method of packaging a thermoplastic or thermosetting hot melt
adhesive, said method comprising the steps of:
a) providing one substantially uniform separate portion of an
adhesive composition;
b) sufficiently solidifying said portion for packaging;
c) selecting a plastic packaging material having a softening point
below about 120.degree. C., and having physical characteristics
which are compatible with and do not substantially adversely affect
the adhesive characteristics of a molten mixture of said adhesive
and said material and whereby said mixture is substantially
compatible with the operation of hot melt application
equipment;
d) substantially completely surrounding said sufficiently
solidified adhesive portion with said plastic packaging
material.
2. The method according to claim 1, further comprising, before step
b), as a step a) coating the adhesive with a separating, anti-stick
substance and pre-cooling the adhesive composition.
3. The method according to claim 1, wherein the packaging material
is a wrap, a sack or a bag made of a plastic film or a net or a
similar apertured enclosure made of plastic, preferably weighing
between 0.1 and 3% by weight with respect to the weight of the
adhesive composition contained in the package.
4. The method according to claim 3, wherein the packaging material
is a sack or bag sealed by welding after filling with the adhesive
composition.
5. A method of packaging a thermoplastic or thermosetting hot melt
adhesive, said method comprising the steps of:
a) providing a plurality of substantially uniform separate portions
of an adhesive composition;
b) sufficiently solidifying all said portions for packaging;
c) forming a batch comprising the plurality of solidified
portions,
d) selecting a plastic packaging material having a softening point
below about 120.degree. C. and having physical characteristics
which are compatible with and do not substantially adversely affect
the adhesive characteristics of a molten mixture of said adhesive
and said material and whereby said mixture is substantially
compatible with the operation of hot melt application
equipment;
e) substantially completely surrounding said batch with said
plastic packaging material.
6. The method according to claim 5, further comprising, before step
b), as a step a) coating the adhesive with a separating, anti-stick
substance and pre-cooling the adhesive composition.
7. The method according to claim 5, wherein the packaging material
is a sack or a bag made of plastic film or a net or similar
apertured enclosure made of plastic, preferably weighing between
0.1 and 3% by weight with respect to the weight of the adhesive
composition contained in the package.
8. The method according to claim 5, the portions being provided by
separating a continuous mass of adhesive composition into roughly
pillow-shaped pieces weighing between 0.1 and 50 grams.
9. The method according to claim 8, the adhesive composition having
a high softening point above about 120.degree. C. and the packaging
being a sack of plastic film material or a net or similar apertured
enclosure made of plastic.
10. The method according to claim 8, the adhesive composition
having a low softening point between about 50.degree. C. and
105.degree. C., and the packaging being a bag of plastic film
material, said bag being sealed by welding after filling with the
adhesive.
11. The method according to claim 10, the bag taking a batch of
about 100 to 4000 grams of pillow-shaped adhesive composition
portion pieces.
12. The method according to claim 10, the plastics film packaging
material having a softening point substantially corresponding to
the softening point of the adhesive composition.
13. The method according to claim 10, the plastics film material
having a thickness in the range between about 5 .mu.m and 200
.mu.m.
14. The method according to claim 9, the plastic material being
selected from the group consisting of ethylene based polymers,
including ethylene/vinyl acetate, ethylene acrylate, ethylene
methacrylate, ethylene methyl acrylate, ethylene methyl
methacrylate, high and low density polyethylene, polyethylene
blends and chemically modified polyethylene, copolymers of ethylene
and 1-6 mono- or di-unsaturated monomers, polyamides, polybutadiene
rubber, polyesters such as polyethylene terephthalate, polybutylene
terephthalate; thermoplastic polycarbonates, atactic
poly-alphaolefins, including atactic polypropylene, and others;
thermoplastic polyacrylamides, polyacrylonitrile, copolymers of
acrylonitrile and other monomers such as butadiene styrene;
polymethyl pentene, polyphenylene sulfide, aromatic polyurethanes;
styrene-acrylonitrile, acrylonitrile-butadiene-styrene,
styrene-butadiene rubbers, polyethylene terephthalate,
acrylonitrile-butadiene-styrene elastomers, polyphenylene sulfide,
A--B, A--B--A, A--(B--A).sub.n --B, (A--B).sub.n --Y block polymers
wherein the A comprises a polyvinyl aromatic block, the B block
comprises a rubbery midblock which can be partly hydrogenated, and
mixtures of said substances.
15. The method according to claim 9, the adhesive composition
portion pieces being cooled to ambient or below ambient in a
cooling bath at least on their outsides and thereafter conveyed to
a netting or bagging station for packaging.
16. The method according to claim 10, the bag filled with the
adhesive composition portion pieces being weld-sealed.
17. The method according to claim 10, at least most of the air
remaining in the bag after filling being removed, bringing the
packaging film material into close contact with the adjoining
adhesive composition pieces.
18. The method according to claim 17, the filled and sealed bag
being compressed or evacuated, and air being forced out from around
and between the portion pieces and out of the bag through pores,
punctures and perforations in the film material and/or through
openings in the weld seam, the batch of adhesive composition pieces
being compacted and the packaging film material being adhered to
the surfaces of the compacted batch.
19. The method according to claim 18, the adhesive in the bag being
sufficiently re-heated before compression or allowed to retain
sufficient internal heat in the cooling step to facilitate
deformation of the packaged adhesive composition portion pieces
during compression.
20. The method according to claim 18, the compression being
provided by means of a press.
21. The method according to claim 18, the compression being
provided by the weight of the stacked filled bags under the
influence of elevated ambient temperature, especially through
stacking the bags in delivery boxes, crates, cartons and such like,
and storing same in a sufficiently heated room.
22. The method according to claim 18, the compression being carried
out at an elevated temperature of 30.degree. C. to 150.degree.
C.
23. A method of packaging a thermoplastic or thermosetting hot melt
adhesive, said method comprising the steps of:
a) providing an adhesive composition in flowable form,
.[.sufficiently plastified.]. for packaging;
b) inserting at least one portion of said flowable.[.,plastified.].
adhesive composition into a plastics packaging material
enclosure;
c) selecting a packaging material having a softening point below
about 120.degree. C. and having physical characteristics which are
compatible with and do not substantially adversely affect the
adhesive characteristics of a molten mixture of said adhesive and
said material and whereby said mixture is substantially compatible
with the operation of the hot melt application equipment; and
d) separating and substantially surrounding said at least one
portion with said plastics packaging material.
24. The method according to claim 23, further comprising, before
step b), .[.as a.]. .Iadd.and after .Iaddend.step a) .Iadd.an
additional step a') .Iaddend.coating the adhesive with a separate,
anti-stick substance and pre-cooling the adhesive to a flowable.[.,
plastified.]. state.[., of the adhesive composition.]..
25. The method according to claim 23, wherein the packaging
material enclosure is a sack or a bag made of plastic film or a net
or a similar apertured enclosure made of plastic, preferably
weighing between 0.1 and 3% by weight with respect to the weight of
the adhesive composition contained in the package.
26. The method according to claim 25, wherein the packaging
material enclosure is a sack or bag sealed by welding after filling
with the adhesive composition.
27. The method according to claim 23, wherein the flowable.[.,
plastified.]. composition has a softening point temperature of
between 50.degree. C. and 100.degree. C.
28. The method according to claim 23, wherein the flowable.[.,
plastified.]. composition is provided by means of a melt extruder
having cooling means for adjusting the temperature of the
extrudate.
29. The method according to claim 1, the plastic packaging material
having a melting or softening point of below about 125.degree.
C.
30. The method of claim 8 wherein the softening point of the
adhesive is below 120.degree. C.
31. The method of claim 8 wherein the softening point of the
adhesive is about 80.degree. C.
32. The method of claim 8 wherein the batch is about 250 to 1000
grams.
33. The method of claim 10 wherein the film thickness is 15 .mu.m
to 50 .mu.m.
34. The method of claim 1 wherein the packaging material has a
softening point of about 90.degree. C. to 120.degree. C.
35. A method of packaging a synthetic block polymer based hot melt
adhesive, said method comprising the steps of:
(a) providing one substantially uniform separate portion of an
adhesive composition comprising a synthetic block polymer based
hot-melt adhesive;
(b) sufficiently solidifying said portion for packaging;
(c) selecting a polyethylene packaging material which is meltable
together with the adhesive composition and blendable into the
adhesive composition in a molten state, said packaging material
being chosen so as to not disadvantageously effect the properties
of the adhesive composition when blended into same, and to be
substantially compatible with the operation of hot melt application
equipment; and
(d) substantially completely surrounding said sufficiently
solidified portion with said polyethylene packaging material.
36. The method according to claim 35 wherein said film material has
a thickness in the range between about 5 .mu.m and 50 .mu.m.
37. The method according to claim 35 wherein said film material has
a softening point below about 120.degree. C.
38. The method of claim 1 comprising the additional step of
applying said molten mixture through hot melt application equipment
having an orifice less than about 0.025 inches in diameter.
39. The method of claim 5 comprising the additional step of
applying said molten mixture through hot melt application equipment
having an orifice less than about 0.025 inches in diameter.
40. The method of claim 23 comprising the additional step of
applying said molten mixture through hot melt application equipment
having an orifice less than about 0.025 inches in diameter.
.Iadd.
41. A method of packaging a thermoplastic or thermosetting hot melt
adhesive, said method comprising the steps of:
a) providing an enclosure comprising a film material having a
softening point below about 120.degree. C., said film material
being compatible with and not substantially adversely affecting the
adhesive characteristics of a molten mixture of said adhesive and
said material, and the operation of hot melt application
equipment;
b) extruding a hot melt adhesive directly into said enclosure until
a desired amount of adhesive is received; and
c) sealing said enclosure to substantially surround said hot melt
adhesive. .Iaddend..Iadd.42. The method according to claim 41
wherein the adhesive has a softening point between about 50.degree.
C. and 100.degree. C. .Iaddend..Iadd.43. The method according to
claim 41 wherein the film material has a softening point of about
90.degree. C. to 120.degree. C. .Iadd.44. A method of packaging a
thermoplastic or thermosetting hot melt adhesive, said method
comprising the steps of:
a) providing an enclosure comprising a film material having a
softening point below about 120.degree. C., said film material
being compatible with and not substantially adversely affecting the
adhesive characteristics of a molten mixture of said adhesive and
said material, and the operation of hot melt application
equipment;
b) filling said enclosure with hot melt adhesive until a desired
amount of adhesive is received;
c) sealing said enclosure to substantially surround said hot melt
adhesive.
.Iaddend..Iadd.45. The method according to claim 44 wherein the
adhesive has a softening point between about 50.degree. C. and
100.degree. C. .Iaddend..Iadd.46. The method according to claim 44
wherein the film material has a softening point of about 90.degree.
C. to 120.degree. C. .Iaddend..Iadd.47. A method of packaging a hot
melt adhesive, the method comprising forming a film material
enclosure substantially surrounding a thermoplastic hot melt
adhesive composition having a softening point less than about
120.degree. C., the adhesive comprising a thermoplastic polymer and
a tackifying resin, the film material having a softening point less
than about 125.degree. C., being compatible with and not
substantially adversely affecting the adhesive characteristics of a
molten mixture of said adhesive and said film material.
.Iaddend..Iadd.48. The method of claim 1 wherein the packaging
material has a sharp melting point. .Iaddend..Iadd.49. The method
of claim 5 wherein the packaging material
has a sharp melting point. .Iaddend..Iadd.50. The method of claim
23 wherein the packaging material has a sharp melting point.
.Iaddend..Iadd.51. The method of claim 35 wherein the packaging
material has a sharp melting point. .Iaddend..Iadd.52. The method
of claim 41 wherein the film material has a sharp melting point.
.Iaddend..Iadd.53. The method of claim 44 wherein the film material
has a sharp melting point. .Iaddend..Iadd.54. The method of claim
47 wherein the film material has a sharp melting point.
.Iaddend..Iadd.55. The method according to claim 47 wherein the
film material has a sharp melting point. .Iaddend.
Description
DESCRIPTION
The present invention relates to a method of packaging an adhesive
composition, especially a thermoplastic or thermosetting hot melt
adhesive, and further to packaged such adhesive compositions.
Thermoplastic adhesives, especially hot melts, can be confectioned
and packaged as e.g. disclosed in German patent 22 48 046.
According to this prior art now widely used throughout the world, a
hot melt adhesive is squeeze-cut into roughly pillow-shaped pieces;
the pieces are subsequently cooled and thus solidified and are then
put into sacks, cartons and such like for packaging.
In order to reduce the tendency of the individual pillows to stick,
i.e. adhere to each other, it is known to coat them with a
separating, anti-stick substance, e.g. a wax or a polymer, compare
also DE 33 27 289 Kaiser.
From WO 84/03457 and WO 84/03468. Societe Nouvelle Raffinerie
Meridionale de Ceresines-Belix, it is known to outwardly coat such
autoprotected blocks with a powdery separating agent.
For thermoplastic adhesive compositions with a relatively high
softening point (ASTM E28-58T), i.e. above 120.degree. C. and
especially above 150.degree. C., these coatings provide sufficient
anti-stick properties. Such compositions can therefore be packaged,
stored and dispensed from sacks, without any major sticking
problems.
Another well-known packaging for adhesive compositions is to wrap
or cast bigger portions of the adhesive in plastics film material,
such as thick polyethylene film.
These known packagings have the disadvantage that the thermoplastic
adhesive composition must be removed from the packaging prior to
use, which means an extra handling step. Further, the packaging
material must be discarded after emptying, which leads to material
waste and expenditure for disposing of the used packaging
material.
A further problem arises with thermoplastic adhesive compositions,
e.g. HMPSA's, having a relatively low softening point, i.e. below
120.degree. C. and especially between 60.degree. C. and 105.degree.
C. Such compositions show marked creep and cold flow properties
even at ambient temperatures. Further, the expansion coefficients
of these materials are sufficiently different from those of the
coating materials as to lead to cracking and peeling of the coating
materials, especially in prolonged storage at varying temperatures.
Thus, the surfaces of the individual adhesive pillows or pieces
become exposed and the pillows stick together, making the handling,
especially the dosing of the adhesive more difficult and again
leading to increased expenditure and handling problems. This is
especially pertinent in cases where the adhesive composition is
exposed to increased pressure and/or temperature during storage or
handling.
From DE 31 38 222 and DE 32 34 065 it is already known to coat the
circumference of elongated hot melt portions of between 1 and 1000
m length with a thin polyolefin film to prevent sticking problems
when winding these string-like portions up onto themselves. The
portions are subsequently cut to make cartridge of cartouche
fillings, whereby the film stays on the circumference and is molten
and applied together with the adhesive.
A similar proposal for extruding a hot melt adhesive into a tubular
film is known from the lecture manuscript reprinted in
"Kontinuierliche Aufbereitung von Haftklebstoffen", 5. Munchener
Klebstoff- und Veredelungs-Seminar, 20. through 22. October 1980.
The use of a co-extruded polyethylene film for manteling a long
string of hot melt adhesive is further known from Swiss patent 431
177.
The above-mentioned prior art documents only relate to the concept
of preventing individual hot melt portion pieces from sticking by
individually coating them with a plastics material film. This is
not suitable for mass-produced thermoplastic adhesive composition
pillows, since it would be very expensive, it would lead to marked
dilution of the adhesive with coating film material and it would
further not be efficient, since in the squeeze-cutting step of
adhesive composition pillow production, it would not be possible to
produce a complete enclosure of the individual pillows by the film.
Thus, relatively large areas of the pillow-shaped portion pieces
would remain uncovered and the sticking problems would not be
effectively overcome.
From German patent 36 25 358 to Hausdorf, it is known to completely
wrap a single solid hot melt adhesive material block in a
thermoplastic, especially a copolyamide film material with melting
point between 120.degree. C. and 150.degree. C., to prevent
sticking of the adhesive to the internal surfaces of a melting
apparatus when pressure-melting the adhesive. The film material is
melted and mixed with the adhesive. This prior art centers on
copolyamide materials in view of their inherent hot melt adhesive
properties.
Today, application temperatures of less than 150.degree. C.,
preferably in the range of 110.degree. C. to 140.degree. C. are
required by the end user to reduce thermal degradation problems of
the adhesive as well as distortion of the substrates used.
Therefore, for most applications, copolyamide films are not
advantageous, in view of their high melting points and problems
encountered in homogeneously melting and mixing such materials
together with customary holt melt adhesives.
It is an important object of this invention to provide a method of
packaging an adhesive composition, especially a thermoplastic or
thermosetting hot melt adhesive, which reduces the amount of
handling necessary in using the adhesive and also reduces or even
eliminates packaging waste.
It is another important object of this invention to provide a
method of packaging an adhesive composition, especially a
thermoplastic or thermosetting hot melt adhesive, which permits the
packaging of low softening point adhesives, such as HMPSA's and
sprayable hot melts, without the sticking and blocking problems
encountered in prior art.
To attain these and other objects and advantages, a method of
packaging an adhesive composition, especially a thermoplastic or
thermosetting hot melt adhesive according to the present invention
comprises the steps of providing one substantially uniform separate
portion of the adhesive composition; sufficiently solidifying said
portion for packaging: substantially completely surrounding said
sufficiently solidified portion with a plastics packaging material:
said packaging material being meltable together with the adhesive
composition and blendable into said molten adhesive composition,
the kind and amount of said packaging material being chosen so as
not to disadvantageously affect the properties of the adhesive
composition when blended into same.
This method is especially suited for the packaging of relatively
large portion pieces of the adhesive, such as individual pieces
weighing between 100 grams and 4 kilograms.
In another aspect of the present invention, a method of packaging
an adhesive composition, especially a thermoplastic or
thermosetting hot melt adhesive, comprises the steps of providing a
plurality of substantially uniform separate portions of the
adhesive composition; sufficiently solidifying all said portions
for packaging; forming a batch comprising the plurality of
solidified portions, and substantially completely surrounding said
batch with a plastics film packaging material or a net or similar
apertured enclosure made of plastics; said packaging material being
meltable together with the adhesive composition and blendable into
said molten adhesive composition, the kind and amount of said
packaging material being chosen so as not to disadvantageously
affect the properties of the adhesive composition when blended into
same.
This method is especially advantageous for the packaging of
pillow-shaped pieces of low softening point thermoplastic adhesives
as described above.
The further independent claims and subclaims as appended hereto
define and describe other advantageous aspects and preferred
embodiments of the present invention.
Packaging single, larger portions or batches of smaller portion
pieces of the adhesive composition into sacks or bags of the
plastics film packaging material according to this invention, or
even wrapping suitable portions of adhesive in such packaging
materials, makes it possible for the user to feed the complete
packaged article, i.e. the adhesive and the packaging material
surrounding it, into the melter. The packaging material is then
molten together with the adhesive composition and is blended into
the composition. In view of the minor amounts of packaging material
required, and the suitable choice of packaging material, especially
with respect to its melting point and compatibility with the
adhesive composition, the properties of the adhesive composition
are not disadvantageously affected by the additional matter.
Thus, it is neither necessary to unpack the adhesive composition
prior to melting and subsequent use, nor is it necessary to dispose
of the packaging material in a separate step.
Larger portions of adhesive composition can be individually wrapped
or bagged in the plastics film packaging material, irrespective of
their softening point.
For adhesives that do not block easily, an apertured enclosure such
as a net can be used.
In the packaging of adhesive compositions, especially sprayable hot
melt adhesives and HMPSA's it is advantageous to employ a further,
more specific aspect of the present invention. It has been shown in
corresponding tests that plastics film sacks containing larger
batches of portion pieces, e.g. pillows of adhesives can cause
problems in melting. In some cases, the film forming the sack does
not melt and blend uniformly into the molten adhesive instead
floating on the surface of the melt and/or adhering to the melter
walls, which can cause major problems. Without wanting to restrict
the invention by any theoretical explanation, it is presently
assumed that this inhomogeneous, non-uniform melting performance is
due to the air enclosed in a plastics film material sack loosely
filled with adhesive composition portion pieces, such as
pillow-shaped pieces, respectively the missing mutual contact
between film material and adhesive composition pieces.
In such cases, it is possible to overcome the homogeneity problem
by using another aspect of the present invention, according to
which a batch, comprising a plurality of separate adhesive
composition portion pieces, is placed in a bag of plastics film
packaging material, said bag being subsequently sealed by welding
or another suitable method, and said bag being voided of air. This
is preferably done by compressing or evacuating the bag at elevated
temperatures. e.g, in a press or simply by storing stacked filled
bags at temperatures of 30.degree. C. to 150.degree. C. The various
thin plastic films (usually 15 um to 100 um thickness) used in this
invention can easily be perforated, so that no further steps need
be taken to permit the escape of air in the compression step.
Additionally, the air can leave the bag through openings in the
weld seams, which are usually not 100% air-tight. It is even
possible that air may leave the bag through pores in the film
material.
In any case, the adhesive pillows are compressed and compacted at
the elevated temperatures mentioned, which entails a degree of
deformation of the portion pieces or pillows; at the same time, the
packaging plastics film material is forced into close contact with
the adjoining adhesive material, and is in most cases adhered to
the adhesive.
This proved to be very advantageous upon subsequent cooling and
storage as well as handling of the finished adhesive packs. Since
the film sticks to the adhesive in the package, it is not easily
damaged and even if punctured or slit, the adhesive remains covered
by the packaging material.
Thus, adhesive packaged according to the invention can be stored,
handled and used without any problems of the individual packs
sticking together or adhering to other objects, even if exposed to
increased pressure and/or temperature and even when low softening
point adhesives are packaged.
Of course, also such low softening point adhesive packages can be
molten with the packaging material blending into the adhesive, thus
realizing the already mentioned advantages with respect to
expenditure.
A plurality of plastics net or film materials can be used according
to this invention. These materials can be selected from the groups
comprising ethylene based polymers such as ethylene/vinyl acetate,
ethylene acrylate, ethylene methacrylate, ethylene methyl acrylate,
ethylene methyl methacrylate, high and low density polyethylene,
polyethylene blends and chemically modified polyethylene,
copolymers of ethylene and 1-6 mono- or di-unsaturated monomers,
polyamides, polybutadiene rubber, polyesters such as polyethylene
terephthalate, polybutylene terephthalate; thermoplastic
polycarbonates, atactic poly-alpha-olefins, including atactic
polypropylene, and others; thermoplastic polyacrylamides,
polyacrylonitrile, copolymers of acrylonitrile and other monomers
such as butadiene styrene; polymethyl pentene, polyphenylene
sulfide, aromatic polyurethanes; styrene-acrylonitrile,
acrylonitrilebutadiene-styrene, styrene-butadiene rubbers,
polyethylene terephthalate, acrylonitrile-butadiene-styrene
elastomers, polyphenylene sulfide, A--B, A--B--A, A--(B--A).sub.n
--B. (A--B).sub.n --Y block copolymers wherein the A comprises a
polyvinyl aromatic block, the B block comprises a rubbery midblock,
which can be partly hydrogenated, and mixtures of said substances,
but other similar materials can be used as well, to match the
properties of the adhesive packaged. Specific examples include
polyethylene films of between 5 .mu.m and 200 .mu.m, preferably
between 15 .mu.m and 50 .mu.m thickness, depending on available
dispensing equipment; such films being especially useful for
packaging low softening point adhesive composition pillows
batchwise into, say, 1000 gram bags with subsequent compression to
remove air.
Another suitable plastics film material is ethylene vinyl acetate
copolymer, with a vinyl acetate content of between 10% and 33%,
especially between 14% and 18% and a softening point between
80.degree. C., and 100.degree. C.
In any case, it is advantageous to restrict the amount of packaging
material used to between 0.1 and 3% by weight with respect to the
weight of the adhesive composition contained in the package. This
prevents undue dilution and corresponding modification of the
adhesives characteristics.
It is further advantageous to suit the softening point of the
packaging material to that of the adhesive composition. Packaging
materials having softening temperature ranges rather than sharp
melting points are less advantageous, since their melting
performance is less predictable and can give rise to problems of
homogeneity in the molten adhesive/packaging material blend.
Generally, packaging materials with melting or softening points
below 125.degree. C., preferably below 120.degree. C. and often
above 90.degree. C. are useful in the context of this
invention.
The envelope containing the discrete adhesive units is made of a
material that when blended into the adhesive does at least not
substantially negatively influence adhesive characteristics, and
preferably is either a component of the adhesive or is a component
physically and chemically compatible with the adhesive in the melt
prior to application. The polymer should not cause a physical
phasing or separation of the adhesive, should not reduce adhesive
properties and should not chemically react with any adhesive
component. Further, the envelope material could be selected to
cooperate with the components of the adhesive unit to enhance a
desired property including, but not limited to, adhesive strength,
pressure-sensitive properties, wet-out properties, cohesive
strength, peel strength, shear strength, oil bleed, rate of cure,
etc. A large number of thermoplastic film forming polymers that can
be used in hot melt adhesives, can be used in manufacturing the
uniquely packaged adhesive of the invention.
Hot Melt Adhesive Systems
Hot melt adhesive systems can apply adhesive through nozzles as
small as 0.012 to 0.025 inches.
Briefly, thermoplastic synthetic resin materials used in hot melt
adhesives comprise a variety of polymerized material. These
polymers are blended with other ingredients such as plasticizer,
tackifier and extender, to form an adhesive. Such polymers include
polyethylene, polypropylene, polyvinyl acetate, polyvinyl butyral,
polyvinylalcohol, ethylene-vinylalcohol polymers and other
polyvinyl resins; polystyrene resins, A--B--A block copolymers
comprising polymers wherein A is a polystyrene block and B is a
rubbery midblock section; acrylic and methacrylic acid ester
resins; various other materials compounded from synthetic resins
such as poly-isobutylene, polyamides, cumarone-indene products and
silicones. Such thermoplastic resins usually have permanent
solubility and fusability so that when hot, they can flow, or creep
under stress and soften to some extent to form a bond. After
cooling, the materials preferably resist creep and bond
deformation. They are used in the manufacture of tape, safety
glass, shoe cements, for the bonding or lamination of film, foil or
non-woven laminates, metals, woods, rubber, paper and many other
materials.
Briefly, thermosetting resin adhesives comprise a variety of
phenol-aldehyde, urea-aldehyde, melaminiealdehyde, and other
condensation polymerization materials including polyepoxy,
polyurethane and silicone resins. Thermosetting resins are
characterized by being converted to insoluble and infusible
materials, sometimes by means of either heat or catalytic action.
Thermosetting adhesive compositions include epoxies, urethanes,
silicones, phenolics, resorcinol, urea, melamine, formaldehyde,
phenol-furfuraldehyde, and the like and are used for the bonding of
wood textiles, paper, plastics, rubber, automative, and appliance
assembly and many other end uses.
Briefly, the adhesives of the natural and bitumen group consist of
those made from asphalt, shellac, rosin and its esters, and similar
materials. They are typically used for bonding of various materials
including minerals, linoleum and the like.
Thermoplastic Polymers
The thermoplastic base polymer that can be used in the manufacture
of the novel adhesive of the invention are thermoplastic polymers
that are sufficiently compatible with tackifier, plasticizer, and
other thermoplastic or thermosetting components to form a
substantial homogenous melt and solid. Typically in the adhesives
of the invention, after the application and the development of
maximum modulus, the polymer provides mechanical strength and a
cohesively competent adhesive bonding mass.
Any of a variety of available thermoplastic materials can be used
in the compositions of the invention. Examples of such
thermoplastics are ethylene based polymers such as polyethylene and
its co- and terpolymers, ethylene/vinyl acetate, ethylene acrylate,
ethylene methacrylate, ethylene methyl acrylate, ethylene methyl
methacrylate, copolymers of ethylene and 1-6 mono- or
di-unsaturated monomers etc., polyamides, polybutadiene rubber,
polyesters such as polyethylene terephthalate, polybutylene
terephthalate, etc., thermoplastic polycarbonates, atactic
poly-alpha-olefins, including atactic polypropylene, and others;
thermoplastic polyacrylamides, polyacrylonitrile, copolymers of
acrylonitrile and other monomers such as butadiene, styrene, etc.,
polymethyl pentene, polyphenylene sulfide, aromatic polyurethanes;
styrene-acrylonitrile, acrylonitrile-butadiene-styrene,
styrene-butadiene rubbers, polyethylene terephthalate,
acrylonitrile-butadiene-styrene elastomers, polyphenylene sulfide.
Also, A--B, A--B--A, A--(B--A).sub.n --B, (A--B).sub.n --Y block
copolymers wherein the A comprises a polyvinyl aromatic block, the
B block comprises a rubbery midblock which can be partly
hydrogenated, and others can be used. The aromatic character of the
polymers provides compatibility with the aromatic plasticizing
agents discussed below and provides controlled compatibility with
the tackifier or the tackifier blends used to control modulus in
the adhesive compositions. The preferred polymers should have a
molecular weight sufficient that, when used in an adhesive
formulation, the adhesive can maintain a high cohesive
strength.
Water soluble thermoplastics such as polyethyloxazoline, polyvinyl
pyrrolidone etc., can be used in the pillow adhesive unit.
Preferred polymers for use in the adhesives of this invention
comprise EVA, APP, linear A--B--A block, linear A--(B--A).sub.n --B
multiblock copolymers, and radial or teleblock copolymers of the
formula (A--B).sub.n --Y wherein A comprises a polystyrene block, B
comprises a substantially rubbery polybutadiene or polyisoprene
block, Y comprises a multivalent compound, and n is an integer of
at least 3. The midblocks can be post-treated to improve their heat
stability through hydrogenation or other post-treatment removing
residual unsaturation. We believe that the size and the amount of
the A or end blocks in the A--B--A block of copolymer structure
should be as much as 15-51 wt-% of the polymer.
While the total styrene content of the polymers can be as much as
51 wt-% of the polymer, and since the polymers can have more than
two A blocks for optional performance, the largest A block should
be less than or equal to about 20 wt-% of the polymers, and, most
preferably, is less than or equal to 15 wt-% of the polymer. In an
S-B-S (styrene-butadiene-styrene) copolymer, the preferred
molecular weight is about 50,000 to 120,000, and the preferred
styrene content is about 20 to 35 wt-%. In an S-I-S
(styrene-isoprene-styrene) copolymer, the preferred molecular
weight is about 100,000 to 150,000 and the preferred styrene
content is about 14-30 wt-%. Hydrogenating the butadiene midblocks
produces rubbery midblocks that are typically considered to be
ethylene-butylene midblocks.
Such block copolymers are available from Shell Chemical Company,
Enichem, Fina and Dexco. Multiblock or tapered block copolymers
(the A--(B--A).sub.n --B type) are available from Firestone under
the STEREON 840A and 845 trademarks.
Another usable polymer is available under the trade name TUFPRENE A
from Asahi, Japan.
The adhesive compositions of the invention can contain other
compatible polymers, fillers, pigments, dyes, oils. catalysts,
inhibitors, antioxidants, UV absorbers, waxes, and other
conventional additives.
Tackifying Resin
The adhesives of the invention can contain a tackifying resin in
combination with a thermoplastic block copolymer optionally with a
plasticizer or other components.
Tackifying resins useful in the adhesives of the invention comprise
rosin derivatives including wood rosin, tall oil, tall oil
derivatives, rosin ester resins, natural and synthetic terpenes and
aliphatic aromatic or mixed aliphatic-aromatic tackifying resins.
Aromatic monomers useful in forming the aromatic containing resin
compositions of this invention can be prepared from any monomer
containing substantial aromatic qualities and a polymerizable
unsaturated group. Typical examples of such aromatic monomers
include the styrenic monomers, styrene, alphamethyl styrene, vinyl
toluene, methoxy styrene, tertiary butyl styrene, chlorostyrene,
etc., indene monomers including indene, methyl indene and others.
Aliphatic monomers are typical natural and synthetic terpenes which
contain C.sub.6 and C.sub.5 cyclohexyl or cyclopentyl saturated
groups that can additionally contain a variety of substantial
aromatic ring substituents. Aliphatic tackifying resins can be made
by polymerizine a feed stream containing sufficient aliphatic
monomers such that the resulting resin exhibits aliphatic
characteristics. Such feed streams can contain other aliphatic
unsaturated monomers such as 1,3-butadiene, cis-1,3-pentadiene,
trans-1,3-pentadiene, 2-methyl-1,3-butadiene, 2-methyl-2-butene,
cyclopentadiene, dicyclopentadiene, terpene monomers and others.
Mixed aliphatic aromatic resins contain sufficient aromatic
monomers and sufficient aliphatic monomers and optionally other
C.sub.3 -C.sub.8 unsaturated monomers to produce a resin having
both aliphatic and aromatic character. The article by Davis, "The
Chemistry of C.sub.5 Resins", discusses synthetic C.sub.5 resin
technology.
Representative examples of such aliphatic resins include
hydrogenated synthetic C.sub.9 resins, synthetic branched and
unbranched C.sub.5 resins and mixtures thereof. Representative
examples of such aromatic tackifying resins include styrenated
terpene resins, styrenated C.sub.5 resins or mixtures thereof. The
selection of tackifying resins is often based on the nature of the
B or midblock radial block copolymer. Rosin derivatives are best
for S-I-S/S-B-S blends and can be used-with either S-I-S or S-B-S
alone. Hydrogenated C.sub.9 or straight aliphatic resins are
preferred for S-I-S copolymers. For S-B-S copolymers, styrenated
terpenes or rosin esters are preferred.
The adhesive compositions of the invention can contain rosin and
rosin derivatives as a tackifying agent Rosin is a solid material
that occurs naturally in the oleo rosin of pine trees and typically
is derived from the oleo resinous exudate of the living tree, from
aged stumps and from tall oil produced as a by-product of kraft
paper manufacture. After it is obtained rosin can be treated by
hydrogenation, dehydrogenation, polymerization, esterification, and
other post treatment processes. Rosin is typically classed as a gum
rosin, a wood rosin, or as a tall oil rosin which indicates its
source. The materials can be used unmodified, in the form of esters
of polyhydric alcohols, and can be polymerized through the inherent
unsaturation of the molecules. Materials are commercially available
and can be blended into the adhesive compositions using standard
blending techniques. Representative examples of such rosin
derivatives include pentaerythritol esters of tall oil, gum rosin,
wood rosin, or mixtures thereof.
Specific examples of useful tackifying resins that can be
compatible with a variety of the thermoplastic resins or
thermosetting resins used in the adhesives of the invention include
materials such as natural and modified rosins, glycerol, and
pentaerythritol esters of natural and modified rosins, copolymers
and terpolymers of natural terpenes, polyterpene resins having a
softening point as determined by ASTM method E28-58 T, of from
about 80.degree. C. to 150.degree. C., phenolic modified terpene
resins and hydrogenated derivatives thereof; aliphatic petroleum
hydrocarbon resins having a ring and ball softening point of from
about 70.degree. C. to 135.degree. C., aromatic petroleum
hydrocarbon resins and hydrogenated derivatives thereof and
alicyclic petroleum hydrocarbon resins and the hydrogenated
derivatives thereof.
Plasticizers
A plasticizer is broadly defined as a typically organic composition
that can be added to thermoplastics, rubbers and other resins to
improve extrudability, flexibility workability, or stretchability.
Typical plasticizers in adhesives are plasticizing oils that are
liquid at typical ambient temperature. The plasticizer used in the
adhesives of the invention can also be typically a solid
composition at ambient temperature having a softening point of at
least 45.degree. C. Preferably, the solid plasticizer if used is a
composition with a softening point of at least 60.degree. C.
Increased softening points (60.degree.-130.degree. C.) can aid in
improving heat resistance or preventing bond failure at high
temperatures.
Plasticizing oils are used in the construction/elastic
attachment/pressure sensitive adhesives of the invention. Such oils
are primarily hydrocarbon oils low in aromatic content. Preferably
the oils are paraffinic or naphathenic in character. The oils are
preferably low in volatility, are clear and have as little color
and odor as possible. The use of a plasticizing oil of this
invention also contemplates the use of olefin oligomers, low
molecular weight polymers, vegetable oils and their derivatives and
similar plasticizing liquids.
One useful class of plasticizers used in the invention comprises a
cyclo-aliphatic or aromatic ester of a benzene dicarboxylic acid.
Such plasticizers are prepared by forming an ester from a
cyclo-aliphatic or aromatic alcohol such as cyclohexanol, phenol,
naphthol, or other monohydroxy alcohol compounds having from 5 to
12 carbon atoms. The ester compounds are formed from dicarboxylic
acid compounds, typically phthalic acids. Phthalic acids that can
be used in the plasticizers are 1,2-benzene dicarboxylic acid,
1,3-benzene dicarboxylic acid (isophthalic acid), or 1,4-benzene
dicarboxylic acid (terephthalic acid). The preferred plasticizers
of this class comprise dicyclohexyl phthalate or diphenyl
phthalate. Most preferably, dicyclohexyl orthophthalate is
used.
A second class of useful plasticizers comprise an aromatic
carboxylic acid ester of a polyfunctional alcohol having 1 to 10
hydroxyl groups. Polyfunctional alcohols that can be used in the
compositions of this class of plasticizers include compounds having
at least two hydroxyl groups and at least two carbon atoms in the
molecule. Specific examples of preferred hydroxy compounds include
ethylene glycol, propylene glycol, 1,2-butylene glycol, 1,4butylene
glycol, glycerine, glucose, fructose, sucrose, mannitol,
trimethylol ethane, 1,4-cyclohexane dimethanol, pentaerytbritol,
2,2-dimethyl-1,3-propane diol, 2-hydroxy
methyl-2-methyl-1,3-propane diol, neopentyl glycol, and other
useful polyfunctional hydroxyl compounds. Aromatic acids that can
be used with the polyfunctional alcohols to form this class ester
plasticizer compounds of the invention include aromatic carboxylic
acids, typically having at least one aromatic group and at least
one carboxyl function. Representative acids include benzoic acid,
naphthanoic acid, and 4-methyl benzoic acid. Typical examples of
such useful plasticizers include triethylene glycol tribenzoate,
trimethylol ethane tribenzoate, glycerol tribenzoate, sucrose
benzoate, pentaerythritol tetrabenzoate, 2,2-dimethyl-1,3-propane
diol dibenzoate, triethylene glycol dibenzoate, glycerol
tribenzoate, 2-hydroxymethyl-2-methyl-1,3-propane diol tribenzoate,
pentaerythrithol tetrabenzoate, neopentyl glycol dibenzoate,
mixtures thereof and others.
A preferred plasticizer is a solid with a softening point above
60.degree. C. which belongs to the class of plasticizers including
cyclohexane dimethanol dibenzoate compounds. A 1,4cyclohexane
dimethanol dibenzoate (containing cis- and trans- isomers) is
exemplified and produces the maximum control over variation and
change in adhesive physical properties.
A third class of useful plasticizers for use in the invention
comprise a sulfonamide class made from aromatic sulfonic acids.
Such plasticizers generally fall within the structural formula:
wherein each R is independently selected from the group consisting
of hydrogen, aliphatic and cyclo-aliphatic radicals having 1 to 12
carbon atoms. Each R can be typically hydrogen, methyl, ethyl,
propyl, isopropyl, n-butyl, isobutyl, tertiary butyl, ethyl hexyl,
neopentyl, cyclohexyl, deodecyl etc. R is preferably methyl, ethyl
or cyclohexyl. Such sulfonamide plasticizers can also be used in
the form of a resinous material formed through the condensation of
formaldehyde with said sulfonamide plasticizer.
Specific examples of adhesive materials that can be used to prepare
the pillows which are stored in the film envelopes of the invention
are as follows:
TABLE I
__________________________________________________________________________
Typical Adhesive Formulations Contact Water Moisture Book
Repulpable Lens Resealable Activated Binding Hot Melt Mounting
Ingredient HM-PSA Adhesive Adhesive Adhesive Adhesive
__________________________________________________________________________
Polyalkylenimine 20-45 30-55 15-60 30-55 15-50 Tackifying Agent
15-40 2-5 -- 2-50 -- Plasticizer + -- 0-20+ 10-30 15-40 -- Wax
(hydroxy) -- 10-35 10-40 5-40 5-60 Filler 25-40 -- -- 0-35 --
Plasticizer (Hydroxy Compound)
__________________________________________________________________________
+Preferably having an agreeable taste or no taste.
The above table sets forth examples of fully functional water
activated adhesives made using a polyethyloxazoline thermoplastic
resin. The fully formulated adhesives made with a
polyethyloxazoline resin are water dispersible or water soluble.
Accordingly, a water insoluble thermoplastic resin is typically
used as an envelope material. Such adhesives can be selected from a
variety of adhesives, however, we have found that small amounts of
A--B--A block copolymer are useful in the polyethyloxazoline
adhesives to increase cohesion and bond strength. However, any
water insoluble film compatible with the polyethyloxazoline can be
used in such an application.
We have found the A--B--A block copolymer, A--B--A--B--A--B
multiblock copolymer and radical block copolymer thermoplastic
resins can be used in a variety of useful adhesives. Such adhesives
are disclosed in Collins. U.S. Pat. No. 4,136,609 which teaches a
particular blend of A--B--A copolymer terpene or synthetic terpene
tackifying resin and oil for use in the preparation of disposable
articles. In addition, the following adhesives can be useful in the
invention:
TABLE II ______________________________________ Low Polymer Resin
Compositions Most Useful Preferred Preferred
______________________________________ Solid Plasiticizer 5-75
10-60 40-50 Tackifier 25-95 30-90 35-65 Polymer 0-15 0-12 0.1-10
______________________________________
TABLE III ______________________________________ Higher Polymer
Resin Compositions Most Useful Preferred Preferred
______________________________________ Solid Plasiticizer 5-70
10-50 20-30 Tackifier 20-85 30-75 35-60 Polymer 10-55 12-35 15-30
______________________________________
TABLE IV ______________________________________ Most Useful
Preferred Preferred ______________________________________ Radial
block copolymer* 5-14 7-13 8-12 A-B-A block copolymer* 0-14 0-12
0-10 Tackifier 45-85 50-80 55-75 Plasticizing Oil 5-35 6-30 8-20
Synthetic 0-10 0.1-9 0.25-5 polyethylene wax (or other oil
complexing agent) ______________________________________ *Total
polymer content (including both radial block and linear block
polymer is typically about 15 wt % or less of the adhesive.
Such hot melt adhesive materials based on A--B--A or other types of
block copolymers can be made into pillows and can be packaged in
envelopes or containers made from the A--B--A or other block
copolymer technology. Since the envelope will comprise from about
0.1 to about 5 wt-% of the total adhesive mass, the amount of block
copolymer used in formulating the adhesive pillow can be reduced
and can be added to the melt in the form of the film enclosure.
One part and two part polyurethane adhesive materials can be used
in preparation of the adhesives of the invention. Such materials
are disclosed in U.S. Pat. No. 4,412,033 and 4,390,678 found in the
table set forth below.
Such adhesives rely on the reactivity between a polyol and a
urethane prepolymer wherein the isocyanate groups condense with
hydroxyl groups and prepolymer. Other types of urethane materials
including hydrocuring or moisture curing urethane adhesives can be
used in the invention. Additionally, two part urethane adhesives
wherein the isocyanate material is formulated and manufactured in
separate pillows from the polyol material can be made.
Additionally, one part urethane adhesives having substantial
proportions of thermoplastic polymers can be used in the adhesives
of the invention. Such adhesives are disclosed in the following
tables.
TABLE V ______________________________________ Typical Preferred
Most Preferred Adhesive Adhesive Adhesive Parts by Parts by Parts
by Weight Weight Weight ______________________________________
Thermoplastic Polymer 1-200 20-175 20-150 Isocyanate Terminated 100
100 100 Prepolymer Tackifying Resin 1-200 20-200 40-135
______________________________________
When using these one part adhesives, the thermoplastic material
from the adhesive can be used to form the packaging film (provided
water vapor permeability of the packaging material is sufficiently
small), with an equal reduction in the percentage of the
thermoplastic and the pillow. The urethane materials set forth
above free of thermoplastic polymer can be packaged in any
compatible resin.
Container or Envelope Film
Any of a wide variety of thermoplastic materials can be used as the
envelope or container material for the nets or the films enclosing
the adhesive. Examples of such thermoplastics are ethylene based
polymers such as ethylene/vinyl acetate, ethylene acrylate,
ethylene methacrylate, ethylene methyl acrylate, ethylene methyl
methacrylate, high and low density polyethylene, polyethylene
blends and chemically modified polyethylene, copolymers of ethylene
and 1-6 mono- or di-unsaturated monomers, polyamides, polybutadiene
rubber, polyesters such as polyethylene terephthalate, polybutylene
terephthalate, etc., thermoplastic polycarbonates, atactic
poly-alpha-olefins, including atactic polypropylene, and others;
thermoplastic polyacrylamides, polyacrylonitrile, copolymers of
acrylonitrile and other monomers such as butadiene, styrene, etc.,
polymethyl pentene, polyphenylene sulfide, aromatic polyurethanes;
styrene-acrylonitrile, acrylonitrile-butadiene-styrene,
styrene-butadiene rubbers, polyethylene terephthalate,
acrylonitrile-butadiene-styrene elastomers, polyphenylene sulfide.
Also, A--B, A--B--A, A--(B--A).sub.n --B, (A--B).sub.n --Y block
copolymers wherein the A comprises a polyvinyl aromatic block, the
B block comprises a rubbery midblock, and others can be used.
The manufacture of such films from thermoplastic materials is
well-known. Such films can range in thickness from about 5 .mu.m to
200 .mu.m, preferably from 15 .mu.m 50 to 50 .mu.m for reasons of
mechanical strength and product integrity.
Such films often contain additional amounts of plasticizers,
stabilizers, dyes, perfumes, fillers and other materials to
increase the flexibility, handleability, visibility or other useful
property of the film.
The melting point or softening point of the film material will be
chosen in view of that of the adhesive to be packaged. Generally,
this melting or softening point will nevertheless be below
125.degree. C., preferably below 120.degree. C. and often above
90.degree. C.
The film material can be packaged in a second outer container or
envelope for a variety of purposes including reducing the exposure
of the film to moisture, or other contaminants, to increase the
handleability of the adhesive and envelope, to provide a surface
for labelling. Such envelopes would be conformed for easy opening
with pull tabs, perforations, or other means well-known in the
art.
In the practice of the present invention, the adhesive composition.
e.g, a hot melt adhesive, is prepared by mixing polymer, synthetic
or natural resin, wax or paraffin and other substances as desired
and well-known in the art, this mixing or blending being carried
out at elevated temperatures and by customary methods.
The adhesive composition is then pumped to an orifice for
dispensing. Usually, a coating with a separating anti-stick
substance will be provided, and the coated composition will be
pre-cooled prior to dispensing.
In a preferred embodiment of this invention, the dispensed
composition is squeeze-cut, and thus separated into individual,
pillow-shaped portion pieces. At this stage, the composition is
already partly solidified, i.e. the individual pieces are
sufficiently solidified at their outside, to be squeeze-cut and
retain their pillow-like shape afterwards, although the interior of
the pillows may still be fairly hot and liquid.
The pillows are thereafter placed in a cooling bath, usually with
water as the cooling liquid and are sufficiently solidified for
packaging. At this stage, the heat remaining in the pillows can be
adjusted by suitable choice of cooling time, to keep the pillows
warm enough for deformation in a subsequent compression step.
The sufficiently solidified pillows are now conveyed to a packaging
station, e.g, a bagging machine and are placed into nets or bags of
plastics film packaging material according to this invention. For
packaging the customary coated hot melt pillows, it is presently
preferred to produce bags from a tubular film of polyethylene or
EVA co- or terpolymer material with 15 .mu.m to 50 .mu.m thickness,
each bag taking about 1000 gram of pillows, although other plastics
materials are also suitable.
Each filled bag is then sealed by a weld seam. At this stage, the
bag contains a fairly loose filling of relatively stiff pillows and
a corresponding amount of air.
In order to reduce the initially mentioned problems in subsequent
use of low softening point adhesive composition pillows packaged
according to this invention, the bag is now either put in a press
and compressed as well as compacted at elevated pressure and
temperature, or it is simply stacked with other, similar bags under
sufficient heat, so that the compression is effected by the weight
of the stack. In the latter case, the heat can be provided by
either placing the stacks in a correspondingly heated room or by
allowing the pillows to retain sufficient internal heat in the
cooling process, this heat then re-softening the solidified outer
regions of each pillow after the packaging.
In another preferred embodiment, the hot melt adhesive will be
extruded from an extruder provided with suitable cooling means, the
adhesive having a temperature of between about 50.degree. C. and
100.degree. C., preferably about 80.degree. C. upon extrusion. The
adhesive is extruded directly into a bag or sack of the film
material according to the invention. The adhesive can be cut or
otherwise comminuted after extrusion and before packaging, but
preferably, the adhesive is extruded into the packaging bag or sack
without such comminution, until the desired amount of adhesive is
received in the package. At this stage, the extruded adhesive is
cut off, the package is sealed and a new bag or sack is connected
to the extruder for filling.
In this embodiment, the extrusion temperature of the adhesive
provides sufficient plasticity and shapability of the adhesive for
substantially uniformly filling the package, without leaving
undesirable voids or damaging the bag or sack in the filling or
packaging process.
Preferred embodiments of the invention will now be described in
more detail, by reference to the following examples.
EXAMPLE 1
Pillows of an EVA-based commercially available HMPSA were placed in
a bag, the bag taking 500 gram of hot melt, and the packaging
material forming 0.25 weight % of the total package.
The bag was made of a plastics material film of 16 .mu.m thickness,
the plastics being a modified ethylene vinyl acetate copolymer with
17% vinyl acetate and a melting point of 94.degree. C.
As a comparison, unpackaged pillows of said adhesive were used.
Both the packaged and the non-packaged hot melt samples were then
molten; the following table shows the properties of the adhesives
thus obtained:
TABLE VI ______________________________________ Brookfield
viscosity (mPa .multidot. s) at 20 rounds Non-packaged Packaged per
minute Adhesive Adhesive ______________________________________ at
120.degree. C. 17 750 18 000 at 130.degree. C. 11 750 11 875 at
140.degree. C. 8 000 7 750 at 150.degree. C. 5 000 5 125 at
160.degree. C. 3 625 3 625 at 170.degree. C. 2 625 2 700 at
180.degree. C. 1 940 2 000
______________________________________
The softening point, determined in accordance with the method
described in ASTM E 28 (Bille and Anneau) was 73.degree. C. for the
non-packaged hot melt and 74.degree. C. for the blend of hot melt
and packaging material.
At 25.degree. C., the penetration according to DIN 51579 was 47 for
the non-packaged adhesive and 46 for the blend.
Within the experimental error margins, the properties of the
adhesive thus remain unaffected by the blending in of the packaging
material in the melting stage.
In another experiment, both above-mentioned adhesive samples were
coated onto a polyester substrate, the adhesion properties in terms
of peeling and shearing being then determined by adhering the
substrate onto different materials.
The following results were obtained:
TABLE VII ______________________________________ Non-packaged
Packaged Adhesive Adhesive ______________________________________
Shearing on cotton 1,46 N 1,31 N Peeling at 23.degree. C.: on
cotton 0,03 N 0,03 N on nylon 0,27 N 0,23 N on silk 0,27 N 0,25 N
Peeling at 35.degree. C.: on cotton 0,62 N 0,66 N on nylon 2.02 N
1.92 N on silk 2,76 N 2,77 N Peeling at 30.degree. C. on cotton:
AFNOR norm) t= 0 minutes 2.37 N 2.68 N T = 15 minutes 2.05 N 2.68 N
______________________________________
Again, the experimental error is larger than the differences of
properties detected, so that it can be stated that the adhesives
show identical performance irrespective of the blending in of the
packaging material in the melting step.
EXAMPLE 2
An EVA film of 100 .mu.m thickness and DSC softening point
108.2.degree. C. was used to package
a) EVA based adhesive pillows
b) APP based adhesive pillows into bags, following the general
procedure as in Example 1.
The adhesive-filled bags were placed in a melter/dispenser
apparatus and melted and applied at 140.degree. C. No influence of
the packaging material component in the adhesive material was
notable in the final product.
EXAMPLE 3
An EVA film of 50 .mu.m thickness (vinyl acetate content 18%) and
DSC softening point 84.3.degree. C. was used to package
a) SB rubber (Tufprene A) based adhesive blocks by wrapping
b) APP based adhesive pillows and
c) SBS rubber based adhesive pillows, both by bagging as in Example
1.
In melting and application of the packaged adhesives a) at
150.degree. C. and b) at 140.degree. C., no influence of the
packaging material was again detectable. When adhesive c) was
melted and applied at 120.degree. C. with air still contained in
the bags, inhomogeneity of the melt was observed. This problem
could be overcome by evacuation of the bags.
EXAMPLE 4
A PE film of 30 .mu.m thickness and DSC softening point 106.degree.
C. was used to package
a) SB rubber based adhesive pillows;
b) SBS rubber based adhesive pillows (as in Example 3), by bagging
as in Example 1.
The unevacuated packs of adhesive a) could be melted at 150.degree.
C. and the adhesive applied without any notable effect of the
plastic film material. Adhesive b) melted and applied at
120.degree. C. again gave inhomogeneity problems unless the packs
were substantially voided of air.
EXAMPLE 5
Tests according to the standard FINAT method were carried out with
the adhesive a) of Example 4, with 60.+-.2 g per m.sup.2 coating on
polyester RN 36. The following table shows the test results:
______________________________________ I. Tack Free Hanging Loop
N/25 mm Non-Packaged Packaged Adhesive Adhesive
______________________________________ without ageing 28.0 28.0
after ageing for 22.5 26.5 12 weeks at 23.degree. C. after ageing
for 23.0 23.7 12 weeks at 50.degree. C.
______________________________________
______________________________________ II. 180.degree. peel
adhesion resistance N/25 mm Non-Packaged Packaged Adhesive Adhesive
______________________________________ without ageing 25.2 24.0
after ageing for 20.2 20.6 12 weeks at 23.degree. C. after ageing
for 20.6 19.6 12 weeks at 50.degree. C.
______________________________________
These test results show that the adhesive properties of the samples
were unaffected by the admixture of the packaging material.
* * * * *