Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
1998-12-11
2001-05-22
Lipman, Bernard (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C526S326000, C526S328500, C526S273000, C525S186000, C525S523000, C525S534000, C525S327300, C525S532000
Reexamination Certificate
active
06235850
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to components of self-fixturing adhesive compositions and methods of their use. The material of the present invention includes an acrylic terpolymer component comprising:
a) 1-30% of total terpolymer weight epoxy-functional (meth)acrylate monomer units,
b) 1-98% of total terpolymer weight tackifier (meth)acrylate monomer units, and
c) 1-98% of total terpolymer weight compatibilizing (meth)acrylate monomer units, wherein said compatibilizing (meth)acrylate monomer unit is a (meth)acrylic ester derived from an aromatic alcohol containing 6-14 carbon atoms.
BACKGROUND OF THE INVENTION
U.S. Pat. No. 5,086,088 concerns PSA-thermoset adhesives comprising blends of acrylic esters and epoxy resins. This reference does not disclose acrylic esters having epoxy functionality.
U.S. Pat. No. 3,312,754 concerns a liquid elastic adhesive comprising an epoxy resin and a butadiene-acrylonitrile-carboxyl terpolymer, wherein the carboxyl groups of the terpolymer will react with the epoxy groups. This reference does not disclose acrylic esters having epoxy functionality.
U.S. Pat. No. 4,199,646 concerns a PSA comprising an epoxy resin and a copolymer of an acrylic ester and a prepolymer having carboxyl, hydroxyalkyl, glycidyl or methylol functions. No terpolymer including a compatibilizing monomer is disclosed.
JP 63-260978 and JP 1-252682 concern PSAs including an acrylic copolymer that contains an epoxy group. No terpolymer including a compatibilizing monomer is disclosed. These references suggest mixing high Mw acrylic copolymer with low amounts of epoxy resin, preferably 1-10% by weight, to form a solid composition.
SUMMARY OF THE INVENTION
Briefly, the present invention provides an acrylate terpolymer comprising: 1-30% of total terpolymer weight epoxy-functional (meth)acrylate monomer units, 1-98% of total terpolymer weight tackifier (meth)acrylate monomer units, and 1-98% of total terpolymer weight compatibilizing (meth)acrylate monomer units, wherein said compatibilizing (meth)acrylate monomer unit is a (meth)acrylic ester derived from an aromatic alcohol containing 6-14 carbon atoms.
The terpolymer is compatible with epoxy resin in a blend to form an improved one-part, solventless self-fixturing adhesive.
In another aspect, the present invention provides a one-part, solventless self-fixturing adhesive or hardenable PSA.
What has not been described in the art, and is provided by the present invention, is a self-fixturing adhesive or hardenable PSA comprising an epoxy resin and an acrylate terpolymer having epoxy functionality and comprising tackifying and compatibilizing monomer units.
In this application:
“epoxy-functional (meth)acrylate monomer” means a monomer of formula I:
where R
2
is H or CH
3
and where R
1
comprises an epoxy group;
“tackifier (meth)acrylate monomer” means a monomer of formula I, above, where R
2
is H or CH
3
and R
1
comprises a monovalent derivative of a tackifier, preferably a straight-chain, branched, cyclic or polycyclic hydrocarbon;
“compatibilizing (meth)acrylate monomer” means a monomer of formula I, above, where R
2
is H or CH
3
and R
1
comprises a monovalent derivative of an aromatic group of between 6 and 14 carbons, preferably also comprising one or more ether linkages;
“monomer unit” means a portion of a polymer derived from a single monomer;
“curing agent”, for epoxy resin, means an epoxy curative or an epoxy catalyst;
“self-fixturing adhesive” and “hardenable PSA” are used interchangeably to mean a substance which is useful as a pressure sensitive adhesive (PSA) in its uncured state and which, after positioning, may then be cured by light, heat, or other means to become a structural adhesive;
“substituted” means substituted by conventional substituents which do not interfere with the desired product, e.g., substituents can be alkyl, alkoxy, aryl, phenyl, halo (F, Cl, Br, I), cyano, nitro, etc.
It is an advantage of the present invention to provide an acrylate terpolymer which is compatible with epoxy resins in a blend, even in equal amounts, to form a one-part, solventless PSA-thermoset adhesive.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
The present invention provides an acrylate terpolymer comprising: 1-30% of total terpolymer weight epoxy-finctional (meth)acrylate monomer units, 1-98% of total terpolymer weight tackifier (meth)acrylate monomer units, and 1-98% of total terpolymer weight compatibilizing (meth)acrylate monomer units, wherein said compatibilizing (meth)acrylate monomer unit is a (meth)acrylic ester derived from an aromatic alcohol containing 6-14 carbon atoms, which is compatible with epoxy resin in a blend to form an improved one-part, solventless self-fixturing adhesive.
The acrylate terpolymer can be made by any appropriate means to polymerize (meth)acrylate monomers, many of which are known in the art. Preferred methods include mixing the monomers in the presence of a free radical initiator such as 2,2′-azobisisobutyronitrile (AIBN). Thermal intiators useful in preparing acrylates included in the invention include, but are not limited to, azo, peroxide, persulfate and redox initiators.
Suitable azo initiators include, but are not limited to, 2,2′-azobis(4-methoxy-2,4-dimethylvaleronitrile) (VAZO™ 33), 2,2′-azobis(2-amidinopropane) dihydrochloride (VAZ™ 50), 2,2′-azobis(2,4-dimethylvaleronitrile) (VAZ™ 52), 2,2′-azobis(isobutyronitrile) (AIBN, VAZO™64), 2,2′-azobis(2-methylbutyronitrile) (VAZ™67), and 1,1′-azobis(1-cyclohexanecarbonitrile) (VAZO™88), all of which are available from DuPont Chemicals, Wilmington, DE, and 2,2′-azobis(methyl isobutyrate) (V-601™), available from Wako Chemicals USA Inc., Richmond, Va.
Suitable peroxide initiators include, but are not limited to, benzoyl peroxide, acetyl peroxide, lauroyl peroxide, decanoyl peroxide, dicetyl peroxydicarbonate, di(4-t-butylcyclohexyl)peroxydicarbonate (PERKADOX™ 16), available from Akzo, Nobel Chemicals, Inc., Chicago, Ill., di(2-ethylhexyl)peroxydicarbonate, t-butylperoxypivalate (Lupersol™ 11), available from Elf Atochem North America, Philadelphia, PA, t-butylperoxy-2-ethylhexanoate (Trigonox™ 21-C50), available from Akzo, Nobel Chemicals, Inc., and dicumyl peroxide.
Suitable persulfate initiators include, but are not limited to, potassium persulfate, sodium persulfate, and ammonium persulfate.
Suitable redox (oxidation-reduction) initiators include, but are not limited to, combinations of the above persulfate initiators with reducing agents such as sodium metabisulfite and sodium bisulfite; systems based upon organic peroxides and tertiary amines, such as benzoyl peroxide plus dimethylaniline; and systems based on organic hydroperoxides and transition metals, such as cumene hydroperoxide plus cobalt naphthenate.
Other initiators include, but are not limited to, pinacols, such as teteraphenyl-1,1,2,2-ethanediol.
Preferred thermal free radical initiators are selected from the group consisting of azo compounds.
The initiator is present in a catalytically-effective amount and such amounts are typically in the range of from about 0.01 parts to 10 parts, and more preferably in the range of from about 0.025 parts to about 2 parts by weight, based upon 100 total parts by weight of the total formulation. If a mixture of intiators is used, the total amount of the mixture of initiators would be as if a single initiator was used.
Photoinitiators that are useful for polymerizing alkyl acrylate monomers include benzoin ethers, such as benzoin methyl ether or benzoin isopropyl ether; substituted benzoin ethers, such as anisoin methyl ether; substituted acetophenones, such as 2,2-diethoxyacetophenone and 2,2-dimethoxy-2-phenylacetophenone; substituted alpha-ketols, such as 2-methyl-2-hydroxypropiophenone; aromatic sulfonyl chlorides, such as 2-naphthalene-sulfonyl chloride; bis-acyl phosphine oxides, such as bis-(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide and 2,4,6-trimethylbenzoyl diphenyl phosphine oxide; photoactive oximes, such as 1-phenyl-1,1-propanedione-2-(
Abuelyaman Ahmed Salih
Ebihara Ikuko
Kangas Lani S.
Perez Mario Alberto
3M Immovative Properties Company
Dahl Philip Y.
Egwim Kelechi
Lipman Bernard
LandOfFree
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