Process of Applying a Cyanoadhesive Composition
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Year:
Abstract:
The present invention provides a cyanoacrylate adhesive composition having high shear bond strength, peeling bond strength, tensile strength and impact bond strength and superior wear characteristics particularly in toy applications where hostile play environments demand hot-cold cycle resistance. The cyanoacrylate adhesive composition contains (a) up to 20% by weight of a cyanoacrylate monomer, (b) a styrene-based elastomeric block copolymer, and (c) a specifc solvent which is selected to effect the solution of both components. The invention is also directed to a method of applying the instant adhesives to substrate surfaces.
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US006660327B2
(54)
United States Patent
(10)
Cordova
(12)
(45)
4,016,327
4,364,876
5,623,010
5,994,464
PROCESS OF APPLYING A
CYANOADHESIVE COMPOSITION
(75)
Inventor:
(73)
Notice:
A
A
A
A
* 4/1977 Fumei et al.
12/1982 Kimura et al.
4/1997 Groves
11/1999 Ohsawa et al.
428/314
260/465.4
524/174
525/85
Assignee: MatteI, Inc., EI Segundo, CA (US)
( *)
Patent No.:
US 6,660,327 B2
Date of Patent:
Dec. 9,2003
Abimael Cordova, Whittier, CA (US)
* cited by examiner
Subject to any disclaimer, the term of this
patent is extended or adjusted under 35
U.S.c. 154(b) by 42 days.
(21)
Appl. No.: 10/034,416
(22)
Filed:
Primary Examiner-Bernard Pianalto
(74) Attorney, Agent, or Firm-Robert W. Mulcahy
(57)
ABSTRACT
Dec. 28, 2001
Prior Publication Data
(65)
us 2003/0125443 A1 Jul.
(51)
(52)
Int. CI?
U.S. CI.
(58)
Field of Search
(56)
3, 2003
B05D 5/10
427/207.1; 427/385.5;
427/393.5; 446/268
427/207.1, 385.5,
427/393.5; 446/268
References Cited
The present invention provides a cyanoacrylate adhesive
composition having high shear bond strength, peeling bond
strength, tensile strength and impact bond strength and
superior wear characteristics particularly in toy applications
where hostile play environments demand hot-cold cycle
resistance. The cyanoacrylate adhesive composition contains (a) up to 20% by weight of a cyanoacrylate monomer,
(b) a styrene-based elastomeric block copolymer, and (c) a
specifc solvent which is selected to effect the solution of
both components. The invention is also directed to a method
of applying the instant adhesives to substrate surfaces.
U.S. PATENT DOCUMENTS
3,264,249 A
* 8/1966 Araki et al.
260/32.4
12 Claims, No Drawings
US 6,660,327 B2
1
2
generally remedied by modifying the cyanoacrylate adhesive compositions with various elastomers, core-shell
polymers, adhesives and reinforcing agents. The present
invention carries this modification concept one step further
BACKGROUND OF THE INVENTION
5 in employing styrene block co-polymers in adhesive applications for toy manufacturing.
1. Field of the Invention
As indicated above, the class of the styrenic elastomeric
The present invention relates to a novel adhesive compomaterials commonly used as the molding material for toy
sition and process for applying a styrenic based adhesive and
doll faces and the harder structural portions of toy articles
cement coatings to thermoplastic polymer surfaces, particularly to toy articles formed of resin materials. Specifically, 10 are A-B-A type block polymers such as styrene-butadienebutylene copolymer-styrene or styrene-butadiene-styrene,
the present invention relates to a cyanoacrylate adhesive
manufactured by Shell and sold under the trademark Kraton.
composition having superior bonding and hot-cold cycle
In the case of a toy having a hard surface comprised of a
resistance characteristics, particularly suited for unfriendly
rigid or semirigid A- B-A styrene based block copolymer, a
toy play environments.
15 compatible elastomeric A-B-A styrene copolymer in the
2. Description of the Related Art
form of styrene-ethylene-butylene-styrene, (SEBS, sold
Children's toys and dolls, in particular, have a history
under the trademark Kraton-G) has been found to be an
dating back into antiquity. Generally, the technology surexceptional modifier of the alpha-cyanoacrylate adhesives to
rounding the manufacture of dolls centers on creation of an
render them useful as glues, cements, or sealants to bond
attractive doll face, miniturized application of conventional
20 mechanical parts in in toy items.
clothes, manufacture of a doll body using plush or other
For adhesives used to bond toy mechanical parts and like
sculptural techniques, and the simulation of the hair with
structures which are used in rugged or otherwise unfriendly
sculptural elements, fibers, or other techniques. In the case
environments it is considered necessary to have not only a
of doll faces, the doll maker has a wide panoply of possible
high bond strength in the normal state of use but also a high
constructions and manufacturing techniques at his disposal.
Traditional techniques involve the use of plaster-like or hard 25 adhesive force to endure the heavy handling of child's play.
Moreover, the bonded mechanical parts must even be
plastics material to cast a doll face. In time, however, soft
capable of withstanding extreme or sudden changes in
rubber materials such as styrene-butadiene rubber (SBR)
temperature caused by leaving the toy item outdoors or
and styrene-butadiene-styrene block copolymer (Kraton)
immersing the toy item in hot and cold water, e.g. a child
elastomers have come to replace plaster and hard plastics in
the production of doll heads because of their realistic look 30 subjecting a doll to a sink bath. Conventional cyanoacrylate
adhesive compositions are not generally satisfactory in
and feel.
meeting these demands as adhesives in toy items.
The soft rubber doll faces include all the normal features
It has been found that a cyanoacrylate adhesive compoof a human figure simulated by the doll including the entire
35 sition containing certain styrenic block copolymers and
head, including well formed lips, teeth, cheeks, nose, chin,
certain solvents results in an adhesive which not only
ears, and forehead. After the injection molding of an elaspossesses high shear adhesive force, peeling bond strength
tome ric doll face, it is finished by applying a dye or other
and impact adhesive force but also exhibits an outstanding
similar material to give the face a natural skin color. Therehot-cold cycle resistance and heat resistance.
after the soft rubbery doll's head must be joined to a body
portion comprised of a torso and limbs to complete a full 40
SUMMARY OF THE INVENTION
bodied toy doll item. This is generally accomplished by
In accordance with the present invention, there is progluing, sealing or cementing the soft eleastomeric head
vided an improved cyanoacrylate adhesive composition parpotion to the headless body section generally composed of
a hard or firm plastic. In selecting an adhesive for the
ticularly useful for toy article applications comprising (1) a
purpose of affixing the dolls'head two considerations are 45 styrenic elastomeric block copolymer, (2) a cyanoacrylate
monomer, and (3) a solvent composition comprised of
important: (1) that the adhesive form a firm and effective
bond and seal between the soft elastomer and the harder
certain high evaporation rate organic solvents. More
resin substrate surface and (2) that the adhesive composition
particularly, the cyanoacrylate adhesive composition is charbe relatively quick drying so as to accommodate expeditious
acterized by containing (a) up to 20% by weight of an alpha
doll manufacturing processes. The principle outlined here 50 cyanoacrylate monomer, (b) a styrenic elastomeric block
copolymer miscible or compatible with the cyanoacrylate
can be applied to any toy parts requiring laminating or
monomer, and (c) an organic co-solvent mixture having
bonding affixation of parts. The present invention provides
solubility parameters compatible with the solubility parama cyanoacrylate adhesive which provides superior bonding
eter of the elastomeric phase of the block copolymer.
and rapid curing or drying.
Specifically provided herein as a preferred embodiment is
It is well known that alpha.-cyanoacrylate (also known as 55
a cyanoacrylate adhesive comprises from about 2% up to
2-cyanoacrylate) adhesives polymerize and cure rapidly in
10% by weight of an alpha alkyl cyanoacrylate, a high
the presence of trace water absorbed on the surface of a
molecular weight styrene-ethylene-butylene-styrene block
material to be bonded, affording an extremely strong bond in
copolymer, and an organic solvent having a solubility coma short time for almost all materials except some inert
materials such as polyethylene and Teflon. Because of such 60 patibility with both components. The solvents are certain
organic liguids which (1) have relatively high evaporation
a superior property, alpha-cyanoacrylate adhesives are
rates, (2) are capable of solubilizing the cyanoacrylate, and
widely used as instantaneous adhesives for a room tempera(3) offer stability to the styrenic copolymer partner in the
ture setting as one-part type adhesives for the bonding of
coating composition and in the elastomeric substrates to
metals, plastics, rubber, wood, etc. However, since the
cyanoacrylate polymer is a brittle polymer, cyanoacrylate 65 which they are applied in that the co-solvent is non-reactive
with and non-destructive to the respective component mateadhesives have the drawback that they are inferior in peeling
rials.
bond strength and impact resistance. This problem has been
PROCESS OF APPLYING A
CYANOADHESIVE COMPOSITION
US 6,660,327 B2
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effective in solubilizing the copolymer and cyanoacrylate
High evaporation rate organic solvents and co-solvents
within the purview of the present invention include isoprene,
and the styrene-based copolymer molecules of the substrate
hexane, heptane, styrene liquid, xylene, toluene,
surface thereby takifying the elastomeric surface to generate
methylcyclohexane, cyclohexane, 2,2-dichloropropane,
a miscible interface with the applied film of adhesive,
methylene chloride, diisobutyl ketone, diisopropylketone, 5 resulting in a very strong amalgam like bonding of the
methyl isobutyl ketone, methyl isopropyl ketone, methyl
adhesive film to the substrate upon drying. When the adhecyclohexanone, cyclohexanone, isobutyl acetate, isopropyl
sive is used to laminate two substrate surfaces an amagam of
acetate, butyl acetate, propyl acetate, ethyl acetate, diethyl
the two surfaces occurs resulting in a strong high peel
ether, dimethyl ether, diethylene glycol, 2-ethylhexanol, and
strength bonding between the two surfaces. The adhesive
mixtures thereof. Anyone or more of these solvents that is 10 composiitons herein have particular advantage and applicacapable of solubilizing both the styrene phase and the
tion to children's toys because of the pervasive use of
elastomeric rubber portions of the styrenic block copolymer
styrenic block soft and hard elastomeric material substrates
of the present cyanoacrylate adhesive composition will
in toy manufacturing and are particularly useful in applicafunction effectively in the instant invention. In the case of
tions to the soft elastomeric materials used in doll facial
the high molecular weight styrenic block SEBS, the solu- 15 structures where the adhesion of these rubber facial strucbility parameter (to be explained below) is about 7.9 from
tures to a hard resin torso and limb structure is expected to
which it can be calculated that a solvent combination or
withstand the rigorous and hostile environment of child use.
blend having a solubility parameter of between 7.4 to 9.4
In a further embodiment, the present invention is even
will be effective within the purview of the instant invention.
more particularly directed to a cyanoacrylate adhesive coatThe high evaporation rates of the instant solvents causes
20 ing composition for elastomeric substrates comprising from
enhancement of evaporation of any water adsorbed on the
about (1) 1.0% to 20% by weight of an alkyl cyanoacrylate,
surface of the resin substrate surface to which the present
(2) styrenic elatomeric copolymer resin selected from the
adhesive to be applied with the result that the water is
group comprising styrene butadiene rubber (SBR), styrenecompletely driven off in an adhesive coating drying step.
butadiene-styrene (S-B-S), and styrene-ethylene-butylene
The present invention utilizes styrene block copolymers
25 styrene (SEBS) elastomeric block copolymers, and (3) an
sold generally under the trademark Kraton by the Shell
organic solvent having a specific Solubility Parameter of
Chemical Company. Kraton polymers can be dissolved in
from about 7.4 to about 9.4. An even more preferred
many single solvents, such as toluene, and in many solvent
adhesive composition comprises (1) from about 2.0% to
blends, such as hexane/MEK. In contrast to the usual
10% of an alkyl cyanoacrylate selected from group complastics and rubbers which have only a single phase, a
30 prising methyl, ethyl, or propyl cyanoacrylate, (2) a styreneKraton polymer has two phases. In order to form a true
ethylene-butylene styrene (SEBS) elastomeric block copolysolution, the solvent system must be capable of dissolving
mer and (3) an organic solvent selected from the group
both of these phases. If blends of solvents are used, and even
consisting of toluene, xylene, heptane, t-butyl acetate and
wider variety of solvent systems may be considered. A
mixtures thereof. As already indicated, this coating compopolymer will generally dissolve in those solvents with
35 sition has been found especially effective in application to
Solubility Parameters close to that of the polymer itself.
styrenic surface subtrates and, particularly, the group comSince Kraton polymers have two different polymers in each
prising styrene butadiene rubber (SBR), styrene butadiene
molecule, a good solvent must have a Solubility Parameter
styrene, and styrene-ethylene-butylene-styrene elastomeric
for both.
copolymer surfaces.
The Solubility Parameter is the Hilderbrand solubility 40
DETAILED DESCRIPTION OF THE
parameter which is a measure of the total forces holding the
INVENTION
molecules of a solid or liquid together. This measurement
and its application to Kraton type copolymers (styrenic
The cyanoacrylate monomer as the first ingredient of the
elastomeric block copolymers) is explained in the publicacyanoacrylate adhesive composition according to the
tion "Solution Processing of Kraton Polymer Coatings" 45 present invention is a compound known well as an alphapublished by the Shell Chemical Company (Dec. 30, 1998)
cyanoacrylate and represented by the following general
and hereby incorporated by reference in its entirety.
formula:
The styrenic copolymer/co-solvent adhesive composiCN
tions made in accordance with the present invention dry in
/
a rapid manner to enable a strong bond of the copolymer 50
CH2=C
with polymeric substrate surfaces thereby engendering firm
\ COOR
bonding of an applied surface with a substrate surface; that
is, a sandwiched film of adhesive between an applied blanket
cover to a substrate will afford an extremely strong bond
where R is an ester residue such as alkyl, cycloalkyl,
between the two surfaces.
55 alkenyl, cycloalkenyl, alkynyl, phenyl, or aryl. The number
The discovery of the present invention is that one may
of carbon atom of the ester residue is not specially limited,
but there usually is employed a hydrocarbon group having 1
formulate a superior adhesive, cement, or glue composition
to 8 carbon atoms. A substituted hydrocarbon group such as
by combining a cyanoacrylate, a styrenic elastomeric
alkoxyalkyl or trialkylsilylalkyl is also employable as the
copolymer and a solvent in certain amounts to form an
adhesive composition of exceptional character when applied 60 ester residue.
to elastomeric substrate surfaces. While the adhesive comAs examples of the cyanoacrylate monomer are mentioned alkyl and cycloalkyl alpha-cyanoacrylates such as
position can be applied to any thermoplastic resin surface,
the instant compositions are especially effective as an adhemethyl alpha-cyanoacrylate, ethyl alpha-cyanoacrylate, propyl alpha-cyanoacrylate, butyl alpha-cyanoacrylate, and
sive for substrates comprised of styrene based elastomers,
those copolymers with a linear A-B-A configuration in 65 cyclohexyl alpha-cyanoacrylate, alkenyl and cycloalkenyl
alpha-cyanoacrylates such as allyl alpha-cyanoacrylate,
which A is a polystyrene endblock. It is believed that the
methallyl alpha-cyanoacrylate, and cyclohexenyl alphasolvent selection or mixture of same herein is particularly
US 6,660,327 B2
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cyanoacrylate, alkynyl alpha-cyanoacrylates such as propstyrene-ethylene-butylene-styrene (SEBS sold commerargyl alpha-cyanoacrylate, aryl alpha-cyanoacrylates such as
cially as Kraton G by The Shell Chemical Company). It has
phenyl alpha-cyanoacrylate and toluyl alpha-cyanoacrylate,
been found that Solubility Parameters of from 7.4 to 9.4 are
hetero atom-containing methoxyethyl alpha-cyanoacrylate,
required for solubilization of both the elastomeric mid-block
ethoxyethyl alpha-cyanoacrylate, furfuryl alpha- 5 and styrenic portions of SEBS. Accordingly, solvents having
cyanoacrylate, silicon atom-containing trimethylsilylmethyl
this solubility characteristic for the I-cyanoacrylate and
SEBS in the most preferred embodiments of the present
alpha-cyanoacrylate, trimethylsilylethyl alphacyanoacrylate, trimethylsilylpropyl alpha-cyanoacrylate and
adhesive composition comprise t-butyl acetate,
dimethylvinylsilylmethyl alpha-cyanoacrylate.
cyclohexanone, heptane, toluene, xylene and mixtures
While any and all the alpha cyanoacrylates operate within 10 thereof. Optimum solvents are solvent blends of heptane/tthe purview of the present invention, the preferred
butyl acetate, toluene/cyclohexanone, and xylene/t-butyl
acetate. These preferred solvents have very high evaporation
cyanoacrylates are alkyl alpha cyanoacrylates having alkyl
rates and maximum compatibility with the high molecular
groups of from 1-8 carbon atoms and most preferred alkyl
weight SEBS copolymer and the I-cyanoacrylate in the
alpha cyanoacrylates are selected from the group comprising
methyl, ethyl, propyl, and butyl alpha cyanoacrylate (also 15 instant adhesive composition.
known as methyl 2-cyanoacrylate, ethyl 2-cyanoacrylate
The styrene based resinous component of the present
etc.)
adhesive composition includes blends prepared by the copoThe second ingredient of the 2-cyanoacrylate adhesive
lymerization of one or more conjugated dienes, such as
compositions according to the present invention is an elasbutadiene, isoprene, and chloroprene with styrene. Useful
tomer which is miscible or compatible with the cyanoacry- 20 blends in the preparation of the instant adhesive composilate monomer. The terms "miscible" or "miscibility" and
tions include styrene butadiene rubber (SBR) and styrene"compatible" or "compatibility" are commonly used in the
butadiene-styrene block copolymer. Styrene-based thermopolymer alloy field. The former represents a state wherein
plastic elastomers comprise blocks of hard segments, e.g.,
the elastomer and the cyanoacrylate monomer are mixed
polystyrene, and blocks of soft segments, e.g., polyisoprene,
microscopically, namely, on a molecular level, while the 25 polybutadiene, poly(ethylene-propylene), poly(ethylenelatter represents a state wherein the elastomer is dispersed
butylene), and polypropylene. Thus, useful styrene-based
macroscopically in the cyanoacrylate monomer in a stable
elastomers may comprise, for example, blocks of polystymanner [see, for example, "Polymer Alloy-Basis and
rene and blocks of polyisoprene, or blocks of polystyrene
and blocks of polybutadiene, or blocks of polystyrene and
Application", edited by Kobunshi Gakkai, published by
Tokyo Kagaku Dojinsha, (2nd Edition, Apr. 16, 1993)].
30 blocks of poly(ethylene-butylene). Examples of the most
The present adhesive composition is the combination of
preferred styrene based thermoelastic elastomers useful in
three key ingredients: the I-cyanoacrylate, the elastomeric
the present adhesive composition, include high molecular
styrene block copolymer, and the solvent comprised of a a
weight styrene-ethylene-butylene-styrene (SEBS) block
high evaporation rate organic solvent or co-solvent having
coplymers (e.g. KRATON G-1650, G-1651, G-1652, and
specific solubility parameters tailored to the solubility of the 35 G-1657). Other styrenic copolymers operable within the
elastomeric copolymer, which combination of characterispurview of the instant invention include styrene-ethylenetics provides for the desirable properties of the instant
propylene-styrene block copolymers (e.g. KRATON
invention recited above. The advantages of the instant
G-1701, G-1702 and G-1762X), all commercially available
composition are generated by the use of particular organic
from Shell Chemical Company as well as combinations of
polymer solvents in combination to enhance the application 40 these block copolymers with SEBS can also be included.
of alphacyanoacrylate/polymer/organic solvent based coatOther styrenic block copolymers include styrene-isopreneing compositions. In particular, the organic solvent or
styrene (S-I-S), natural butyl rubber (NBR), and styreneco-solvent used in the present adhesive composition must
ethylene-styrene (S-E-S). Styrene-ethylene-butylenepossess (1) a high evaporation rate, (2) polymer solubilizastyrene (SEBS) copolymers are particularly effective
tion charateristics, i.e. it must be capable of dissolving 45 because they have superior physical properties manifested in
styrene based polymers and copolymers, and (3) styrene
the cyanoacrylate adhesives of the present invention, includbased stability, i.e. the solvent must be non-reactive with
ing durability in that the instant adhesives can withstand
styrene based polymers so as to not chemically degrade
prolonged wear and tear in the form of impact resistance and
them in solution or on a substrate containing styrene based
flexibility. Since the cyanoacrylate is present in a minimum
polymers upon which the coating is to be applied. Solvents 50 of up to 20% by weight, the amount of thermoplastic block
possessing these characteristics include isoprene, hexane,
copolymer elastomer useful in the present adhesive compoheptane, styrene liquid, xylene, toluene, methylcyclohexane,
sitions is not critical in achieving the desired characteristics;
cyclohexane, 2,2-dichloropropane, methylene chloride,
that is, the block copolymer can be present in any amounts
of between 80 to 99 wt %.
diisobutyl ketone, diisopropylketone, methyl isobutyl
The compositional weights recited herein are based on the
ketone, methyl isopropyl ketone, methyl cyclohexanone, 55
resin/Lcyanoacrylate composition and inclusion of any
cyclohexanone, isobutyl acetate, isopropyl acetate, butyl
additives will accordingly affect the overall compositional
acetate, propyl acetate, ethyl acetate, diethyl ether, dimethyl
weight but the ratio of styrenic resin to the alpha cyanoacryether, diethylene glycol, 2-ethylhexanol and mixtures
late will remain the same as initially formulated; that is, a
thereof. Other solvents within the purview of the present
invention include terpenes such as limonene, d-limonene, 60 5% by weight cyanoacrylate in 95 wt % of a styrenic
l-limonene, all taught in common assignee owned U.S.
copolymer blend will remain in the same ratio to one another
patent application Ser. No. 09/921,116 filed on Aug. 2, 2001,
even with the addition of dye or pigment.
which solvents may be used in combination with the high
It is to be emphasized that the purview of the composievaporation rate solvents but not preferably because the
tional invention herein is the combination of a styrene based
terpenes have inherently lower evaporation rates.
65 thermoplastic polymer and a I-cyanoacrylate mixture in
As indicated above, a preferred elastomeric styrenic block
certain amounts for adhesion application to elastomeric
copolymer in the instant invention is high molecular weight
substrate surfaces. As indicated above, especially effective
US 6,660,327 B2
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elastomers are styrene-ethylene-butylene-styrene (SEES)
copolymers which are solvated very effectively with the
solvents recited, the compatibility between the polymer and
the solvents being speculated as being due to the mutual
unsaturation in the solvents and the ethylene-butylene segment of the styrenic polymer. The particular compatibility of
the solvent and the SEES polymer in the coating composition follows on through application to a solid molded or
otherwise formed SEES or other styrenic block copolymer
substrate surface, which acts as an optimal substrate surface
for application of the SEES/cyanoacrylate/solvent adhesive
composition. Accordingly, the most preferred embodiment
of this invention is an application of an SEES/alpha
cyanoacrylate/solvent mixture adhesive coating to a solid
molded SEES substrate surface.
It is apparent that the adheive coating solution may
contain the same styrenic co-polymer as that material
co-polymer in the substrate to be coated. In fact the solubilizing effects of the instant specialized solvents on the
styrenic copolymer in the instant adhesive coating composition encourages application of the coating to a similar or
identical co-polymer substrate surface so that compatible
adhesion takes place between the solubilized co-polymer in
the adhesive coating solution and that similar or identical
co-polymer material in the substrate to which the coating is
to be applied. An application of the subject adhesive coating
include the steps of (i) providing an elastomeric resin
substrate; (ii) applying a composition comprising from about
1.0% to 20.0% by weight of a cyanoacrylate, from 80% to
99.0% by weight of a styrenic block copolymer resin in a
solvent mixture to the elastomeric substrate; and (iii) curing
the applied composition to form a layer of adhesive on the
elastomeric substrate.
The coatings and adhesive compositions herein are characterized by viscosities approaching that of ordinary viscous
glue formulations. A dried coat of the instant formulations
have elongation values and adhesion characteristics conforming to the quality and safety standards necessary for
application to toy products. In addition, these adhesives have
ultimate tensile values of greater than about 500 psi indi eating that toughness is not being sacrificed to flexibility in
the use of these coating compositions. It is important that
coatings or adhesives used for application to toy articles,
such as a soft elastomeric doll facial element, have high
tensile strength so that the coated or painted article have
child use durability especially as to stretchability. The
instant adhesive compositions have flexibility at both ambient and cold temperatures.
The instant coating may contain a pigment, dye, or
colorant in amounts of up to 3% by weight in addition to the
thermoplastic elastomeric resin, the cyanoacrylate, and
organic solvent. The pigment used herein is not particularly
limited and various inorganic or organic pigments can be
employed. Concrete examples of pigments and colorants
are: synthetic organic colorants sold as the T-series by the
Day Glow Corporation of South Gate City, Calif. Other
pigments which can be used include sodium aluminum
sulpho silicate sold as MR 582 by the Cleveland Pigment
Corp. of Cleveland, Ohio; polyamide condensates with
organic dyes with less than 2% phthalocyanine; and tetrachloro-zincate sold by the Day Glow Corporation.
In addition to the additives mentioned above, compositions made in accordance with the present invention may
additionally employ small amounts of agents such as ethylene glycol and clay mixtures to provide the desired texture
and body for ease of application of the instant adhesive
coating compositions. In certain adhesive applications, fill-
ers and stabilizers such as organic and inorganic fibers, sand,
talc and mixtures thereof may also be included as part of the
coating composition. Compositions of the present invention
can be applied by any means such as with a spatula, brush,
a cloth, or a spray applicator. The surface of a polymeric
substrate surface should be clean and dry before application
of the instant adhesive coating. Once applied the compositions should be allowed a sufficient period to allow curing of
the composition by drying of the solvent.
Having generally described the present invention, the
following examples are set for the below to further demonstrate compositions embodying the present invention. The
compositions of the present invention are prepared by adding a specified amount of cyanoacrylate to styrenic block
copolymer resins in a particular solvent mixture under
agitaiton. Specified amounts of other ingredients are added
where indicated. In the following Example 1, the applied
composition is subjected to a Surface Coating Adhesion
(Tape Pull) Test, and a Shear and Stretch Tests to determine
the adhesion and stretch characteristics of the present
cyanoacrylate/styrenic elastomeric block copolymer/organic
solvent adhesive coating composition. These tests are carried out employing standard Quality and Safety Operating
Procedures of the Assignee of the present application,
MatteI, Inc.
The shear strength test is a measure of the cohesiveness or
internal strength of an adhesive. It is based upon the amount
of force required to pull an adhesive strip from a standard
flat surface in a direction parallel to the surface to which it
has been affixed with a definite pressure. It is measured in
terms of time (in minutes) required to pull a standard area of
adhesive coated sheet material for a stainless steel test panel
under stress or a constant, standard load.
5
10
15
20
25
30
35
40
45
50
55
60
65
EXAMPLE 1
4 percent by weight of I-methyl cyanoacrylate is added to
96 percent by weight of a high molecular weight styreneethylene-butylene-styrene (SEES) copolymer elastomer
known as Kraton 1650 and dissolved in 200 mls of at-butyl
acetate/heptane/cyclohexanone cosolvent mixture (in a
20/30/50 volume ratio) in a flask. After complete disolution
of measured quantities of the styrenic elastomer and
cyanoacrylate, a viscous solution is achieved significantly
greater than water. A molded soft elastomeric rubbery doll
face comprised of a solid molded SEES elastomeric copolymer is provided and the cyanoacrylate adhesive composition
applied to the back surface of the molded doll face for
intended adhesion and affixation to a doll torso body structure comprised of a hard elastomeric styrenic copolymer
surface. The rubbery doll facial item was fitted to the torso
by applying the adhesive coated back surface to and affixing
the face to the doll body. The constructed item was allowed
to dry for 3 minutes. Thereafter the rubbery doll face and
body structure were subjected to 1600% Elongation Test, a
Shear Test, and a Peel Test to stress the adhesive laminate.
The tests revealed that the adhesive laminate did not split,
peel, or abrade under the tests, the doll's head remaining
firmly on the torso body. The surface bonding between the
adhesive coating on the backside of the doll's face and the
surface substrate of the torso was so strong and uniform so
as cause complete adhesion between the styrenic coating and
the elastomeric substrate surface of the doll body.
EXAMPLE 2
100 grams of the same styrenic thermoplastic elastomer of
Example 1 (Kraton 1650) and 10 grams of
US 6,660,327 B2
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2-ethylcyanoacrylate were dissolved in a 100 mls volume of
a heptane/xylene/toluene solvent mixture in a wide mouth
beaker. After complete disolution of the styrenic thermoplastic elastomer with difficult stirring, the viscosity of the
solution was approximate that of a thick glue. Thereafter a
hard thermoplastic styrenic copolymer substrate surface is
provided and a dab of the viscous glue is applied to the hard
surface and as separate piece of rubbery material, comprised
of Kraton G material, is patched onto the dabbed viscous
area. After drying for an hour the patched rubber item was
found glued tenaciously to the hard thermoplastic elastomeric substrate surface without any damage to the surface.
Attempts at removal of the patch results in damage to the
hard elastomeric substrate surface because of the tearing
action.
The adhesive compositions of the present invention possess unique combinations of properties, including both a
high degree of elastic durability under suddenly applied
stresses, and a high degree of plasticity when the stress is
applied more slowly. The miscible character of the styrenic
polymer/cyanoacrylate/solvent composition when applied to
a molded polystyrene endblocked polymer substrate surfaces causes an anneal like bonding with that substrate
surface so as to form a physically indistinguishable layer
with that surface. Accordingly the well bonded compositionallayer reacts to the physical stresses applied to the body
of the substrate in exactly the same manner as the underlying
substrate. Therefore the bond created by the adhesives
herein will stretch, strain, and impact as its substrate underlayer and shoe no splitting or peeling. Other properties
include excellent stability throughout a very wide temperature range.
Having thus described the principals of the invention,
together with illustrative embodiments thereof, it is to be
understood that although specific terms are employed, they
are used in a generic and descriptive sense and not for the
purpose of limitation, the scope of the invention being set
forth in the following claims.
What is claimed:
1. A process for applying a coating to a surface comprising the steps of:
(i) providing a thermoplastic elastomeric resin substrate;
(ii) contacting the elastomeric substrate surface with an
adhesive composition comprising a styrenic copolymer
resin, an alpha cyanoacrylate, and a high evaporation
rate solvent, the alpha cyanoacrylate being present in
an amount of 2.0 to 10 weight percent based on the
weight of the styrenic copolymer resin; and
(iii) curing the applied composition to form an adhesive
layer on the elastomeric substrate.
2. The process of claim 1 wherein the high evaporation
rate solvent is selected from the group comprising isoprene,
hexane, heptane, styrene liquid, xylene, toluene,
methylcyclohexane, cyclohexane, 2,2-dichloropropane,
methylene chloride, diisobutyl ketone, diisopropylketone,
methyl isobutyl ketone, methyl isopropyl ketone, methyl
cyclohexanone, cyclohexanone, isobutyl acetate, isopropyl
acetate, butyl acetate, propyl acetate, ethyl acetate, diethyl
ether, dimethyl ether, diethylene glycol, 2-ethylhexanol and
mixtures thereof.
3. The process of claim 2 wherein the high evaporation
rate solvent is selected from the group consisting essentially
of t-butyl acetate, cyclohexanone, heptane, toluene, xylene
and mixtures thereof.
4. The process of claim 1 wherein styrenic copolymer
resin is selected from the group consisting essentially of
styrene butadiene rubber (SBR), styrene butadiene styrene
(SBS), styrene-isoprene-styrene (S-I-S), natural butyl rubber
(NBR), styrene-ethylene-propylene-styrene (SEPS),
styrene-ethylene-styrene (SES), and styrene-ethylenebutylene-styrene (SEBS) copolymer.
5. The process of claim 1 wherein the alphacyanoacrylate
is I-alkyl cyanoacrylate and the alkyl group contains from 1
to 8 carbon atoms.
6. The process of claim 1 wherein the I-alkyl cyanoacrylate is selected from the group consisting essentially of
methyl, ethyl, and propyl cyanoacrylate or mixtures thereof.
7. A process for applying an adhesive to a surface of a toy
item comprising the steps of:
(i) providing an elastomeric resin substrate comprised of
a high molecular weight styrene-ethylene-butylenestyrene block copolymer in the form of a facial doll
element;
(ii) contacting the elastomeric substrate surface with of an
adhesive composition comprising a styrenic copolymer
resin, an alpha cyanoacrylate, and a high evapoation
rate solvent to a surface of the facial doll element; and
(iii) curing the applied composition to form an adhesive
layer on the selected surface of the doll face item.
8. The process of claim 7 wherein the composition
comprises comprising from about 2.0 to 10.0 weight % of
the alpha cyanoacrylate based on the weight of the styrenic
copolymer resin in the composition.
9. The process of claim 7 wherein the cyanoacrylate is
I-alkyl cyanoacrylate and the alkyl group contains from 1 to
8 carbon atoms.
10. The process of claim 9 wherein the solvent has a
solubility parameter of from 7.4 to 9.4.
11. The process of claim 10 wherein the high evaporation
rate solvent is selected from the group consisting essentially
of t-butyl acetate, cyclohexanone, heptane, toluene, xylene
and mixtures thereof.
12. The process of claim 10 wherein the solvent is a
co-solvent mixture and the styrenic copolymer resin in the
coating composition is selected from the group of copolymers consisting essentially of styrene butadiene rubber
(SBR), styrene butadiene styrene (SBS), styrene-isoprenestyrene (S-I-S), natural butyl rubber (NBR), styreneethylene-propylene-styrene (SEPS), styrene-ethylenestyrene (SES), and styrene-ethylene-butylene-styrene
(SEBS) copolymer.
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