U.S. patent number RE35,144 [Application Number 08/290,636] was granted by the patent office on 1996-01-09 for thixotropic adhesive gel.
This patent grant is currently assigned to Borden, Inc.. Invention is credited to John Anderson, Peter S. Columbus, Yogeshbhai B. Patel.
United States Patent |
RE35,144 |
Columbus , et al. |
* January 9, 1996 |
Thixotropic adhesive gel
Abstract
A water based thixotropic adhesive gel is disclosed which
consists essentially of: water; partially hydrolyzed polyvinyl
alcohol, or wherein a portion of the polyvinyl alcohol is replaced
with polyvinylpyrrolidone; a water-soluble high viscosity
thickening agent polymer which is compatible with the polyvinyl
alcohol and which imparts thixotropic properties to the gel; a
water-soluble plasticizer for the polyvinyl alcohol; and a
watersoluble defoamer in proportion of ingredients so that the
viscosity of the adhesive will break down when a flexible tube or
squeeze bottle dispenser is finger-pressed and have a sufficiently
low viscosity to allow for easy extrusion from an orifice having a
diameter of about 0.06 to 0.12 inches. When pressure is released,
after the desired amount of adhesive has flown out of the
dispenser, the adhesive quickly reverts to very close to its
original gel state so that it will not run on a vertical surface on
porous and semiporous surfaces such as paper. An article of
manufacture is also provided whereby the adhesive gel containing
the above ingredients is in a flexible dispenser from which the
adhesive can be dispensed by finger-pressure.
Inventors: |
Columbus; Peter S. (Melville,
NY), Anderson; John (Hilliard, OH), Patel; Yogeshbhai
B. (Gahanna, OH) |
Assignee: |
Borden, Inc. (Columbus,
OH)
|
[*] Notice: |
The portion of the term of this patent
subsequent to December 5, 2012 has been disclaimed. |
Family
ID: |
25524219 |
Appl.
No.: |
08/290,636 |
Filed: |
August 15, 1994 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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976553 |
Nov 16, 1992 |
5284897 |
|
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Reissue of: |
150435 |
Nov 10, 1993 |
05322880 |
Jun 21, 1994 |
|
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Current U.S.
Class: |
524/459; 524/55;
524/458; 524/916; 206/813 |
Current CPC
Class: |
C09J
129/04 (20130101); C09J 129/04 (20130101); C08L
2666/26 (20130101); C08L 2666/28 (20130101); Y10S
206/813 (20130101); Y10S 524/916 (20130101); C08L
2666/26 (20130101); C08L 2666/28 (20130101) |
Current International
Class: |
C08L
9/04 (20060101); C08F 2/12 (20060101); C08F
2/16 (20060101); C08K 3/00 (20060101); C08K
3/20 (20060101); C08L 9/00 (20060101); C08F
002/16 (); C08K 003/20 (); C08L 009/04 () |
Field of
Search: |
;524/55,458,459,916
;206/813 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Other References
Kelzan, Xanthan Gum, Technical Bulletin DB-15 (of Merck and
Company). .
Kelco, Xanthan Gum, Third Edition of Kelco A Division of Merck and
Company. .
Handbook of Water-Soluble Gums and Resins, R. L. Davidson, 1980,
McGraw Hill, pp. 20-18, 20-11, 20-20, 21-15, 21-16. .
Mucilage Adhesive (Commercial Product)..
|
Primary Examiner: Lesmes; George F.
Assistant Examiner: Copenheaver; Blaine R.
Attorney, Agent or Firm: Stevens, Davis, Miller &
Mosher
Parent Case Text
This .Iadd.is a reissue of application Ser. No. 08/150,435, now
U.S. Pat. No. 5,322,880, which .Iaddend.is a divisional of
application Ser. No. 07/976,553 filed on Nov. 16, 1992 now U.S.
Pat. No. 5,284,897.
Claims
What is claimed is:
1. An article of .[.manufacturing.]. .Iadd.manufacture
.Iaddend.comprising:
A. a flexible dispenser wherein the dispenser has a dispensing
opening of from about .[.0.011 to 0.12 .]. .Iadd.0.0028 to about
0.018 .Iaddend.square inches and contains a clear adhesive gel
which can be dispensed therefrom by finger-pressure to form a glue
line which does not run when extruded on paper in a vertical
position;
B. said clear adhesive gel comprising:
(1) about 70% to 93% of water;
(2) about 5% to 25% of a partially hydrolyzed polyvinyl
alcohol:
(3) about 0.5% to 3% of a water soluble plasticizer for the
polyvinyl alcohol;
(4) a water soluble defoamer in an amount sufficient to prevent air
bubbles from destroying the clarity of the gel; and
(5) a water soluble thickening agent polymer compatible with the
polyvinyl alcohol and in an amount sufficient to provide the gel
with a thixotropic index of about 1.5 to 4.5, said thickening agent
selected from the group consisting of sodium
carboxymethylcellulose, sodium alginate and xanthan gum.
2. The article of claim 1 wherein the dispenser has a dispensing
opening of from 0.06 to 0.15 inches in diameter.
3. The article of claim 2 which consists essentially of: 75% to 93%
water; 5% to 20% of polyvinyl alcohol; 0.5% to 1.5% of the
thickening agent: 0.5% to 3% of the plasticizer; and 0.05% to 0.35%
of the defoamer.
4. The article of claim 2 wherein the portion of the dispenser with
the gel contained therein is transparent.
5. The article of claim 2 wherein .Iadd.the plasticizer is a member
selected from the group consisting of .Iaddend.propylene glycol,
glycerol, ethylene glycol, and diethylene glycol.
6. The article of claim 2 whereto the gel can be laundered out of
clothing in hot or cold water after .[.is.]. .Iadd.it .Iaddend.has
dried.
7. The article of claim 2 wherein the gel has a wet tack of at
least 225 grams per square inch and a time of set of about 16 to 35
seconds at 25.degree. C. and a relative humidity of 35%.
8. The article of claim 1 wherein the flexible dispenser is a clear
bottle.
9. The article of claim 1 wherein the flexible dispenser is a clear
tube.
10. The article of claim 2 wherein the dispenser has a dispenser
opening of from 0.07 to 0.10 inches in diameter.
11. The article of claim 1 wherein the thickening agent is xanthan
gum.
12. An article of manufacture comprising:
A. a clear flexible plastic dispenser wherein the dispenser has a
dispensing opening .[.if.]. .Iadd.of .Iaddend.from about .[.0.011
to 0.12 .]. .Iadd.0.0028 to about 0.018 .Iaddend.square inches and
contains a clear adhesive gel which can be dispensed therefrom by
finger-pressure to form a glue line which does not run when
extruded on paper in a vertical position:
B. clear adhesive gel comprising of:
(1) about 70% to 93% of water:
(2) about 5% to 25% of a partially hydrolyzed polyvinyl
alcohol:
(3) about 0.5% to 3% of a water soluble plasticizer for the
polyvinyl alcohol;
(4) a water soluble defoamer in an amount sufficient to prevent air
bubbles from destroying the clarity of the gel; and
.[.(50 .]. .Iadd.(5) .Iaddend.about 0.5% to 1.5% of a water soluble
thickening .[.agnet.]. .Iadd.agent .Iaddend.polymer compatible with
the polyvinyl alcohol to impart a thixotropic index to the gel of
about 1.5 to 4.5, said thickening agent selected from the group
consisting of sodium carboxymethylcellulose, sodium alginate and
xanthan gum.
13. The article of claim 12 wherein the dispensing opening has a
diameter of 0.07 to 0.10 inches.
14. The gel of claim 13 wherein the thickening agent is xanthan
gum.
15. The gel of claim 13 wherein from about 5% to 50% of the
polyvinyl alcohol is replaced with polyvinylpyrrolidone.
16. The gel of claim 13 wherein the quantity of water is from about
75% to 93% by weight of the gel and the polyvinyl alcohol is from
about 5% to 20% by weight of the gel.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a clear, thixotropic, water based general
purpose, polyvinyl alcohol adhesive gel for porous and semiporous
substrates such as paper, card board, cloth and wood.
2. Background Art
Many different general purpose adhesives are available for adhering
porous and semiporous substrates such as paper. However, such
adhesives have shortcomings for use in projects which are performed
on wall boards and other vertical surfaces such as in a class room
by young children.
The adhesive gels of this invention consist essentially of: water;
a partially hydrolyzed polyvinyl alcohol: a water-soluble
thickening agent polymer which is compatible with polyvinyl
alcohol: a water-soluble defoamer: and a water-soluble plasticizer
for the polyvinyl alcohol which does not destroy the clarity of the
gel. Optionally, other ingredients can be added which do not
destroy the advantageous properties of the gel. Compatible
preservatives are generally added to the gel.
The Handbook of Water-Soluble Gums and Resins by R. L. Davidson,
1980 by Mc Graw-Hill. Inc. pages 20-20 discloses partially
hydrolyzed polyvinyl alcohol as an adhesive and page 20-18
discloses the use of certain gelling agents to control penetration
of polyvinyl alcohol solutions into porous substrates or to prevent
run-off of coating by dipping whereas page 20-19 of that reference
discloses the use of an antifoam agent with polyvinyl alcohol.
Pages 21-15 and 21-16 of the Handbook reference describe adhesive
properties of polyvinylpyrrolidone (PVP). Among other shortcomings,
these references do not mention the use of thixotropic agents with
polyvinyl alcohol nor proportions of ingredients used in obtaining
the advantageous properties of this invention.
U.S. Pat. No. 3,442,845 of May 6, 1969 to P. Columbus et al.
relates to polyvinyl acetate adhesives which are redispersible in
cold or hot water. The adhesive compositions of the 845 patent use
polyvinyl alcohol. water-soluble gums, and cellulose ethers as
anti-coalescing agents for the polyvinyl acetate. Propylene glycol
and other polyhydroxy compounds are mentioned as plasticizers for
polyvinyl alcohol. However, among other shortcomings in relation to
the adhesive gel of this invention, the adhesive of the 845 patent
does not have the thixotropic properties, clarity, or rate of set
of the adhesive gel of this invention.
U.S. Pat. No. 4,251,400 of Feb. 17, 1981 to P. Columbus also
relates to a polyvinyl acetate adhesive which is redispersible in
hot and cold water in the dried film form and which uses
polyvinylpyrrolidone and a nonvolatile, water-soluble, plasticizer
as the anti-coalescing agent. In addition to the polyvinyl acetate
and polyvinylpyrrolidone that patent also mentions the use of
polyvinyl alcohol, propylene glycol, as well as water-soluble
ethers in the adhesive composition. The adhesive of the 400 patent
lacks many of the properties of the adhesive gel of this invention
such as rate of set, clarity, and the thixotropic properties.
A mucilage containing about 83% of water: 14% of partially
hydrolyzed polyvinyl alcohol; 0.2% of a water-soluble
polyalkoxylated polyether defoamer; 1.8% of propylene glycol and a
total of about 0.25% of boric acid and citric acid as thickeners is
a well known commercial product. Again, this mucilage lacks
properties of the adhesive gel of this invention such as the
thixotropy and wet tack.
European Patent Application Publication Number 0210052 to
.[.Locktire.]. .Iadd.Locktite .Iaddend.which was published on Jan.
28, 1987 relates to various tubes for dispensing reactive adhesives
such as cyanoacrylate at a rate of one or two drops at a time. The
patent mentions resilient plastic tube dispensers and broadly
states that the adhesive can be thixotropic.
SUMMARY OF THE INVENTION
In one aspect of the invention, a clear, water based polyvinyl
alcohol adhesive gel is provided which contains a water-soluble
high viscosity thickening agent polymer which provides thixotropic
properties to the gel, a water-soluble plasticizer for the adhesive
polymer, and a water-soluble defoamer. Due to its thixotropic
properties, the viscosity of the adhesive will break down when a
flexible tube or squeeze bottle is finger-pressed and have a
sufficiently low viscosity to allow for easy extrusion from a small
orifice such as one having a diameter of about 0.06 to 0.15 inches.
When pressure is released after the desired amount of adhesive
flows out of the orifice, the adhesive quickly reverts to very
close to its original gel state so that a horizontal line of the
gel will not run when applied to a vertical surface of a porous
substrate such as paper.
In another aspect, the adhesive gel is crystal clear or
transparent.
In still another aspect, the adhesive gel has a strong wet tack
with a low rate of set. This holds a second substrate in position
with a first substrate in a vertical plane after contact of the
substrates with the gel while permitting sliding and repositioning
of the second substrate for a prolonged period of time prior to
formation of permanent adhesion and fiber tearing bonds due to
setting of the adhesive.
In a further aspect of the invention, a portion of the polyvinyl
alcohol adhesive polymer is replaced with polyvinylpyrrolidone.
In still another aspect, an article of manufacture is provided
whereby the adhesive gel of this invention is contained in flexible
dispenser having an orifice of about 0.06 to 0.15 inches in
diameter from which the adhesive can be dispensed by
fingerpressure.
In still a further aspect, the orifice of the flexible dispenser is
interrelated with the thixotropic index and viscosity of the gel to
permit extrusion of the gel from the flexible dispenser by applying
finger-pressure to the dispenser and wherein the extruded gel forms
a bead which does not run when applied in a horizontal line on
paper in a vertical plane.
Additional aspects of the invention will be evident from reading of
the entire specification and claims.
Advantages of the invention include: (1) The adhesive gel will not
run when applied to porous and semiporous vertical surfaces and
will not spill when used as a general purpose school glue. (2) The
adhesive gel extrudes easily and in a steady stream from a small
orifice when a flexible tube or squeeze bottle is finger pressed
and reverts to gel when finger-pressure is released. (3) The
combination of adhesive gel and small dispenser opening, e.g. from
about 0.06 inches to 0.15 inches in diameter, minimizes or
eliminates wrinkling of paper upon drying of the adhesive. (4) The
adhesive in a clear resilient plastic dispenser can be viewed
within the dispenser as clear which may include a tint of color (5)
The adhesive gel is preferably crystal clear or has a clear colored
tint and provides a clear dry film. (6) The dry adhesive film is
flexible and will not crack on bending. (7) The adhesive gel has a
strong wet-tack to hold paper surfaces together while drying. (8)
It has a long rate of set so as to permit sliding and positioning
of substrates before fiber tearing permanent adhesive bonds are
developed. (9) The adhesive gel as well as dried films thereof will
launder-out in hot or cold water. (10) The adhesive gel can be
tinted easily with non-toxic water-soluble dyes. (11) The adhesive
gel is non-toxic and is not an irritant to the skin and eyes as
defined in the Federal Hazardous Substances Act.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side elevation of a flexible tube dispenser containing
the adhesive gel of this invention.
FIG. 2 is a plan view of that shown in FIG. 1.
FIG. 3 is a side elevation of a flexible squeeze bottle containing
the adhesive gel of this invention.
FIG. 4 is a plan view of that shown in FIG. 3.
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a conventional, flexible plastic, low density,
polyethylene tube dispenser 10 having a clear hollow tube portion
12 which has a capacity of about 3 fluid ounces and a crimped,
closed end 14. The wall thickness of the polyethylene is 0,018
inches. The closed end beyond crimp 14 has an extending flap 16
which has a cut out portion 18 so that the dispenser 10 can be hung
up and displayed or stored. The dispensing end 20 of tube 12 has a
conventional screw threaded dispenser closure cap 22 which can
effect opening and closing of orifice 26 by holding cap 22 in place
while twisting cap end 74. Dispenser 10 contains adhesive gel 40 of
this invention and the adhesive 40 in contact with tube 12 provide
a clear appearance when the dispenser is viewed.
FIG. 2 more clearly shows dispenser opening 26 at the end of cap
24.
FIG. .[.2.]. .Iadd.3 .Iaddend.shows a clear, conventional, flexible
plastic. low density polyethylene squeeze bottle 30 which has a
capacity of 4 fluid ounces. Bottle 30 has neck portion 32 which has
an open end with conventional screw threads, not shown.
Conventional dispenser closure cap 22 has internal screw threads
which mate with those on neck portion 32. Cap 22 can effect opening
and closing of orifice 26 by twisting of the cap end 24 as with
FIGS. 1 and 2. Dispenser bottle 30 contains clear gel adhesive 40.
The clarity or transparency of the portion of bottle 30 containing
the adhesive 40 is similar to that of FIG. 1.
FIG. 4 more clearly shows dispenser opening 26 at the end of cap
24.
In place of a flexible plastic tube or squeeze bottle, other
dispensers such as deformable, ductile, metal tubes can be used;
although such tubes do not provide for clarity.
The preferred adhesive gels of this invention are clear. The term
"clear" is used herein in contrast to opaque. The term "clear"
includes transparent, i.e., see through, as well as
translucent.
The term "water-soluble" as used herein refers to solutions of
either solids or liquids which are soluble or miscible in water to
provide a solution which is clear at the concentration
employed.
The "thixotropic index" is the difference in viscosity for the gel
from an undisturbed state to that wherein the gel is being
displaced by force. The term "thixotropic" as used herein is also
meant to cover pseudoplastic. The thixotropic index used in this
invention permits extrusion of the gel from the dispenser opening
by use of finger-pressure on a flexible dispenser such as a tube or
squeeze bottle. The adhesive rapidly reverts to a higher viscosity
after extrusion from the orifice. The adhesive gel does not run,
i.e. spread without the application of external force, when applied
to paper in a vertical plane when extruded through the small
orifices of the dispesnsers used in this invention, although there
can be a slight amount of creep such as that of less than 0.15
inches and preferably less than 0.1 inches. The smaller orifices in
the dispensers such as those of less than 0.1 inches in diameter,
e.g., 0.073 inches in diameter minimize any creep.
The thixotropic index for the adhesive gel of this invention varies
from about 1.5 to 4.5 preferably about 1.5 to 4 and particularly
1.8 to 2.5. The thixotropic index used herein is obtained by
dividing the viscosity reading of the gel at 2 RPM (revolutions per
minute) by the viscosity reading at 20 RPM by use of an RVF
Brookfield viscometer using a number 6 spindle at 25.degree. C. The
viscosity readings are taken after the gel has been at rest e.g.
undisturbed, for a period of time such as 12 hours after any
agitation or other disturbance of the gel structure. It should be
noted that different methods for measuring thixotropic index will
give different results.
The adhesive gels of this invention have a viscosity of about
30,000 cps (centipoise) to 100,000 cps at 25.degree. C. and
preferably about 50,000 cps to 90,000 cps at 25.degree. C. as
measured with an RVF Brookfield viscometer by use of a number 6
spindle at 2 RPM (revolutions per minute). When measured at 20 RPM
with an RVF Brookfield viscometer at 25.degree. C. by use of a No.
6 spindle, the viscosity is about 15,000 cps to 60,000 cps,
preferably about 20,000 cps to 40,000 cps, provided that the
thixotropic index is within the ranges set forth herein.
The major ingredient in the adhesive gel of this invention is
water. The quantity of water can vary over a broad range such as
that from about 70% to 93% by weight of the adhesive gel,
preferably 75% to 93% and particularly from about 80% to 90% by
weight thereof.
POLYVINYL ALCOHOL ADHESIVE POLYMER
The adhesive agent used in this invention is partially hydrolyzed
polyvinyl alcohol or such polyvinyl alcohol with
polyvinylpyrrolidone (PVP) wherein the PVP replaces up to about
half of the polyvinyl alcohol. The polyvinyl alcohol will normally
have a molecular weight of about 25,000 to 100,000 and preferably
about 40,000 to 80,000. The viscosity of the polyvinyl alcohol can
vary over a wide range such as that of about 5 or 6 cps, which is
referred to in the art as low viscosity, to 40 to 50 cps, which is
referred to in the an as high viscosity as measured with an LVF
Brookfield viscometer using a number 1 spindle at 60 RPM at
20.degree. C. for a 4% aqueous solution. The preferred degree of
hydrolysis for the partially hydrolyzed polyvinyl alcohol is 87% to
89%.
The PVP can have a molecular weight, expressed as a K value, which
vanes over a wide range such as that of a K value of about 26 to
100.
The quantity of polyvinyl alcohol or polyvinyl alcohol together
with PVP in the gel can vary over a wide range such as that of from
about 5% to 25% by weight of the adhesive gel, preferably from
about 5% to 20% and particularly 10% to 15% by weight of the
adhesive gel.
THE HIGH VISCOSITY THICKENING AGENT POLYMER
The high viscosity thickening agent polymer can be any watersoluble
thickener polymer which is compatible with polyvinyl alcohol and
which imparts thixotropic or pseudoplastic properties within the
thixotropic index and viscosity ranges of the adhesive gels of this
invention. By "compatible" we mean miscible in that it does not
cause separation of the ingredients in the gel. Illustrative of the
high viscosity thickening agent polymer there can be mentioned the
sodium salt of carboxymethylcellulose, also referred to herein
simply as CMC. sodium alginate, and xanthan gum. The quantity of
the thickener is that which is sufficient to provide the adhesive
gel with the desired thixotropic index and viscosity. Such quantity
will generally vary from about 0.5% to 1.5% by weight of the
adhesive gel and preferably from 0.85% to 1.25% by weight of the
adhesive gel.
THE WATER-SOLUBLE PLASTICIZER
Any water-soluble plasticizer for the polyvinyl alcohol which does
not destroy the clarity of the gel is suitable for use in this
invention. Such plasticizers soften the polyvinyl alcohol, make the
adhesive stickier, and assist in making the dried film easier to
wash out of clothing. Illustrative of such plasticizers there can
be mentioned: alkanes having from 2 to 5 carbon atoms and 2 to 3
hydroxyl groups such as: propylene glycol; glycerol; ethylene
glycol; and diethylene glycol; although ethylene glycol and
diethylene glycol can have some toxic properties. The quantity of
the water-soluble plasticizer is that which is sufficient to
plasticize the polyvinyl alcohol and will generally vary from about
0.5 to 3% by weight of the adhesive gel.
THE WATER-SOLUBLE DEFOAMER
Conventional water-soluble defoamers can be used in this invention
such as the polyalkoxylated polyethers e.g., butoxy
polyoxyethylene-propoxyl propylene glycol. Silane defoamers can
also be used but they can adversely affect transparency of the gel.
The quantity of the defoamer is that which is sufficient to
eliminate air bubbles in the gel in a concentration which destroys
the clarity of the gel. Generally, the quantity of the defoamer
varies from about 0.05% to 0.35% by weight of the gel composition.
The defoamer also maintains density of the gel, prevents excessive
foam in the manufacturing process, and facilitates filling of the
dispensers with the gel.
In operation of the dispenser, the cap end 24 is twisted so as to
open the orifice 26 and finger-pressure between the thumb and
forefinger or the thumb and fingers is used to dispense the gel 40
from the dispenser tube 12 or dispenser squeeze bottle 30 on to a
substrate such as paper. The dispenser cap orifice 26 has a
diameter of about 0.06 to 0.15 inches, preferably 0.07 to 0.10
inches and particularly about 0.07 to 0.08 inches. The thixotropic
gel adhesive 40 flows out of the cap orifice 26 in a steady stream
on being finger-pressed due to its thixotropic properties in spite
of its high viscosity in the undisturbed state. The dispensing
opening need not be circular, provided that such opening has a
cross section which in relation to the thixotropic ratio and
viscosity of the gel permits extrusion of the gel by
finger-pressure on the flexible dispenser while a bead of the
extruded gel in a horizontal line on a vertically mounted sheet of
paper does not run. The area of such opening should be from about
.[.0.011 to about 0.12.]. .Iadd.0.0028 to about 0.018
.Iaddend.square inches.
When applied to a substrate in the vertical plane, the gel does not
run and has a minimum amount of creep due to the thixotropic
properties of the gel. Any such creep is generally less than 0.15
inches and more often less than 0.1 inches. Due to the ability of
the thixotropic gel to be applied through a small dispenser
opening, a thin glue line can be provided on a first substrate such
as construction paper which minimizes the amount of adhesive as
well as wrinkling of paper upon drying. When a second
.[.substrates.]. .Iadd.substrate, .Iaddend.such as a second piece
of construction paper is pressed over the first piece in order to
be adhered thereto, the high tack of the gel holds the second
substrate in place on the vertical surface. The slow rate of set
permits a prolonged period of time for positioning the second
substrate such as by sliding of the second surface over the first
before fiber tearing adhesive bonds develop between the two
substrates which permanently hold the pieces in place.
In order that those skilled in the art may more fully understand
the invention presented herein, the following examples are set
forth. All parts and percentages in the examples, as well as
elsewhere in this application, are by weight, unless otherwise
specifically stated. Also, set forth below are procedures for
determining "wet tack" and "rate of set".
PROCEDURE FOR DETERMINING WET TACK
This procedure uses blocks of Grade 1 or Grade 2 white pine with
each block being 2 inches long, 0.75 inches high and 1.75 inches
wide. The grain of the wood is parallel to the length of the block
and the sides which are 0.75 inches high and 2 inches long are
planed and smooth. Such sides are referred to herein as test sides.
Each test side therefor provides a surface of 1.5 square
inches.
A series of tests are performed with the above described blocks of
wood with two blocks being required for each test. In each test an
eye screw is placed in the center of one of the test sides of each
block. Gel adhesive is then placed on the opposite side of the eye
screw of one of the test blocks so that it covers the entire 1.5
square inches of surface. The test side of the second block
opposite the second block eye screw and the side of the first block
having the glue thereon are pressed against each other in sliding
relationship while being placed in register so that the edges of
one block do not extend beyond the edges of the other. A scale is
attached to the eye screw of the first block whereas a weight is
attached to the eye screw of the second block. The scale is then
lifted upwardly by the operator and the two blocks are lifted
vertically so as to lift the weight. Thus, The operator lifts the
scale by hand which in turn lifts the first block through the eye
screw. This in turn lifts the second block due to the wet tack of
the adhesive which in turn lifts the weight which is attached to
the second block eye screw. This test is repeated with clean blocks
of wood and the weight is increased each time until the adhesive
between the two blocks fails to lift the second block and its
attached weight. The last weight which was lifted in this test is
referred to as the quantity of wet tack or simply wet tack of the
adhesive. This test measures the wet tack in a direction which is
perpendicular to the adhered surfaces. In spite of the lengthy
description of this test, it can be performed, and for reliability
is performed, rapidly by the operator. The glue, when the wet tack
is measured between the blocks of wood is very close to the
physical and chemical condition of the glue when it left the
dispenser orifice. The wet tack is a measure of what is often
referred to as the grabbing power of the adhesive. A minimum amount
of wet tack is needed when gluing .[.on.]. .Iadd.one
.Iaddend.substrate to another in a vertical plane, otherwise, the
substrate which is not held in place but rather depends on the wet
glue for positioning would slip off of the vertical surface of the
first substrate. The wet tack of the gel of this invention
preferably vanes from about 225 g per square inch to over 600 grams
per square inch and preferably from about 250 to 500 grams per
square inch.
PROCEDURE FOR DETERMINING RATE OF SET
Determinations for the rate of set are performed on a white paper
pad. A glue line is placed on smooth white paper of a 5.5.times.8.5
inches paper pad. The single glue line is placed in about the
middle of the pad parallel to the length of the paper. This glue is
then spread evenly by the use of a No. 22, WIRE-CATOR which is
supplied by the Leneta Company. The WIRE-CATOR is also referred to
as a wire wrap rod. The WIRE-CATOR draws down a uniform thickness
of film from the single glue line. Use of the No. 22 WIRE-CATOR
draws down a glue line to a thickness of 1.5 rail.
A second sheet of the same paper has one of its narrow ends raised
so that it can be grasped by the fingers. The second sheet is
pressed over the first sheet. The two pieces are then slowly pulled
apart by lifting the raised end of the second sheet and holding the
first sheet down in place. The time that it takes to encounter
fiber tearing bond is the rate of set. The preferred rate of set
for the gels of this invention is from about 16 seconds to 35
seconds and preferably from about 18 to 32 seconds.
The values for both the wet tack and rate of set recited herein are
obtained at 25.degree. C. and a relative humidity of 35%.
EXAMPLE 1
This example shows the composition, preparation and properties of
an adhesive gel of this invention as well as use of an article of
this invention.
______________________________________ Ingredient Parts By Weight
______________________________________ Deionized water 83.51
Polyvinyl alcohol.sup.1 13.33 Sodium salt of 1.00
Carboxymethylcellulose.sup.2 DEFOAMER.sup.3 0.25 Ethyl
parahydroxybenzoate 0.05 Benzoic Acid 0.10 Propylene Glycol 1.75
Blue dye.sup.4 0.01 ______________________________________ .sup.1
VINOL 523 which is a partially hydrolyzed polyvinyl alcohol
supplied by Air Products and Chemicals, Inc. .sup.2 CMC 7HX4 which
is supplied by the Aqualon Company of Wilmington, Delaware. .sup.3
DEFOAMER 622 which is a monofunctional polyalkoxylated polyether
defoamer supplied by the Thomas W. Dunn Corp of Ridgefield, N.J.
.sup.4 No. 5601, FD&C Blue No. 1 which is supplied by Warner
Jenkinson Cosmetic Colors of South Plainfield, New Jersey.
The adhesive of Example 1 was prepared by slowly adding the
polyvinyl alcohol and CMC to water under fast agitation in a
jacketed tank equipped with agitators. The CMC is preferably dry
blended with a portion of the polyvinyl alcohol before addition to
the water. The defoamer was then added. A small portion of the
total amount of water in the gel can be obtained from steam
condensation when the mixture is heated in contact with steam. The
ethyl parahydroxybenzoate and benzoic acid were then mixed in the
composition and the temperature of the mixture was raised to
85.degree. C. to 90.degree. C. with slow agitation for about 15 to
20 minutes until the composition was smooth and homogeneous. The
composition was then cooled to 50.degree. C. with continued slow
agitation. The blue dye was then added which had been prepared in
advance by mixing 2 parts of the dye with 98 parts of water. Mixing
was continued until the batch color was uniform.
The adhesive was then filled into 3 fluid ounce clear, low density
polyethylene tubes 12 having a cap 22 and nozzle 24 and opening 26
of 0.073 inches in diameter. After filling, the back end of tubes
12 are heat sealed to form a crimp 14 having flap 16 extending
therefrom as shown in .[.Fig Land.]. .Iadd.FIG. 1 and .Iaddend.FIG.
2. The portion of the tube 12 in direct contact with the gel 40 was
transparent with a slight blue tint. The portion of tube 12 which
was not in direct contact with the gel was translucent.
All of the examples set forth herein were performed in much the
same manner as with EXAMPLE 1.
The adhesive gel of Example 1 was transparent with a blue tint,
easily dispensed with finger-pressure from the resilient plastic
tube 12 having an orifice 26 of 0.073 inches diameter. It had wet
tack of 435 g (grams) per square inch and a time of set of 25
seconds. It was free of air bubbles, and when dispensed from such
tube and orifice on to a sheet of paper held vertically, it formed
a uniform, thin, horizontal bead of adhesive which did not run and
formed fiber tearing adhesive bonds on drying to a clear film. The
gel can be dispensed in a steady stream through the dispenser
orifice. The strong wet tack held a second sheet of paper in place
on the vertical surface while the lengthy time of set permitted
sliding and repositioning of the second sheet on the first before
permanent adhesive bonds were formed. The gel washed out of
clothing both before and after drying. This product exhibited all
the advantages set forth in the hereinabove Summary of Invention.
It had a thixotropic index of about 2. The viscosity of the
adhesive gel when measured at 25.degree. C. with an RVF Brookfield
viscometer with a No. 6 spindle was as follows:
.[.Initial ly,.]. .Iadd.Initially, .Iaddend.after manufacture, and
at a speed 2 of RPM, a viscosity of 50,000 to 60,000 cps.
Initially, after manufacture, and at a speed of 20 RPM, a viscosity
of 24,000 to 28,000 cps.
After standing for about 12 hours and at a speed of 2 RPM, a
viscosity of 70,000 to 80,000 cps.
After standing for about 12 hours and at a speed of 20 RPM, a
viscosity of 30,000 to 40,000 cps.
After one month from manufacture, the viscosity was not over
100,000 cps when measured at a speed of 2 RPM. The adhesive of this
invention had a pH of 4.8.
EXAMPLE 2
This example provides another formulation having the advantageous
properties of this invention and illustrates the use of a lower
viscosity polyvinyl alcohol. The blue dye, CMC and defoamer were
the same as in EXAMPLE 1.
______________________________________ Ingredient Parts By Weight
______________________________________ Deionized water 76.84 Blue
dye 0.01 Polyvinyl alcohol* 20.00 CMC 1.0 Defoamer 0.25 Ethyl
parahydroxybenzoate 0.05 Benzoic acid 0.10 Propylene glycol 1.75
______________________________________ *VINOL 205 which is a
product supplied by Air Products and Chemicals, Inc
This gel had a viscosity of 67,500 cps at 2 RPM and 21,000. cps AT
20 RPM when measures at 25.degree. C. with a Brookfield RVF
viscometer having a No. 6 spindle. The thixotropic index was 2.4
and it had a wet tack of 250 g per square inch.
EXAMPLE 3
This example illustrates the use of smaller quantities of the
polyvinyl alcohol and CMC which produced product having the
advantageous properties of this invention.
______________________________________ Ingredient Parts By Weight
______________________________________ Deionized water 85.4 Blue
dye 0.01 Defoamer 0.25 Polyvinyl alcohol* 11.6 CMC 0.87 Propylene
Glycol 1.75 Preservative** 0.10
______________________________________ *VINOL 540 which is supplied
by Air Products and Chemicals, Inc. for a partially hydrolyzed
polyvinyl alcohol having a high viscosity and a percent hydrolysis
of 87% to 98%. **KATHON LX 1.5 which is a mixture of
5chloro-2-methyl-4-isothiazolin-3-one and
2methyl-4-isothiazolin-3-one which is supplied by Rohm and Haas
Co.
The blue dye, defoamer and CMC used in EXAMPLE 3 were the same as
that of EXAMPLE 1.
EXAMPLE 4
This example illustrates the formula of a composition of this
invention which contains a substantial quantity of
polyvinylpyrroliodine.
______________________________________ Ingredient Parts By Weight
______________________________________ Deionized Water 83.51
Defoamer 0.25 Polyvinyl alcohol 6.67 CMC 1.00 Polyvinylpyrrolidone*
6.66 Propylene Glycol 1.75 Blue dye 0.01 Ethyl parahydroxybenzoate
0.05 Benzoic acid 0.10 ______________________________________
*LUVISCOL K90 which is supplied by B.A.S.F. Akhengesellschaft.
The adhesive gel of this EXAMPLE 4 had a viscosity of 35,000 cps at
2 RPM and 20,000 cps at 2 RPM when measured by use of a Brookfield
RVF viscometer at 25.degree. C. with a No. 6 spindle. The
thixotropic index was 1.75 and the wet tack was 250 g per square
inch. The polyvinyl alcohol, CMC, and blue dye were the same as
that used in EXAMPLE 1.
EXAMPLE 5
This example illustrates a composition of this invention which used
xanthan gum as the thickening agent polymer.
______________________________________ Ingredient Parts By Weight
______________________________________ Deionized water 83.51 Blue
dye 0.01 Polyvinyl alcohol 13.33 Xanthan gum.sup.1 1.00 Defoamer
0.25 Ethyl parahydroxybenzoate 0.05 Benzoic acid 0.10 Propylene
glycol 1.75 ______________________________________ .[.KELAZAN,.].
.Iadd.KELZAN,.Iaddend. an industrial grade xanthan gum supplied by
the Kelco Division of Merck & Co.
The gel of EXAMPLE 5 had a viscosity of 62,000 cps and 13,500 cps
for a thixotropic index of about 4.6. The viscosity was measured at
25.degree. C. by use of a Brookfield RVF viscometer with a No. 6
spindle. This product had a wet tack of 400 grams per square
inch.
EXAMPLE 6
This example shows the use of sodium alginate as the thickening
agent polymer for preparing a gel adhesive of this invention. The
remaining ingredients are the same as those used in EXAMPLE 1.
______________________________________ Ingredient Parts By Weight
______________________________________ Deionized water 83.51 Blue
dye 0.01 Polyvinyl alcohol 13.33 Sodium alginate* 1.00 Defoamer
0.25 Ethyl parahydroxybenzoate 0.05 Benzoic acid 0.10 Propylene
glycol 1.75 ______________________________________ *KELGIN MV which
is supplied by the Kelco Division of Merck & Co.
The gel of this EXAMPLE 6 had a viscosity of 35,000 cps and 23,000
cps when measured at 2 RPM and at 20 RPM respectively with a
Brookfield RVF viscometer at 25.degree. C. using a No. 6 spindle.
It had a thixotropic index of about 1.5 and a wet tack of 335 g per
square inch.
EXAMPLE 7
This example shows incompatibility of hydroxypropyl methylcellulose
as the thickening agent polymer.
This formulation was unsatisfactory since a thick layer of the
.[.hydroxypropyl/methlcellulose.]. .Iadd.hydroxypropyl
methylcellulose .Iaddend.separated and formed on top of the
sample.
______________________________________ Ingredient Parts by Weight
______________________________________ Deionized water 83.51
FD&C No. 1 (2% aqueous solution) 0.01 Polyvinyl alcohol 13.33
Hydroxypropyl methylcellulose* 1.00 Defoamer 0.25 Ethyl
parahydroxybenzoate 0.05 Benzoic acid 0.10 Propylene glycol 1.75
______________________________________ *METHOCEL K 15 MS which is
supplied by the Dow Chemical Co. Apart from th hydroxypropyl
methylcellulose, the remaining ingredients were the same as that of
EXAMPLE 1.
EXAMPLE 8
The substitution of hydroxyethyl cellulose for the hydroxypropyl
methylcellulose of the formulation in EXAMPLE 7 also gave
unsatisfactory results since a thick layer of the hydoxyethyl
cellulose separated out of the formula.
* * * * *