JPH0940930A - Reactive hot-melt adhesive composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a novel reactive hot-melt adhesive compsn. which is excellent in initial adhesive properties, adhesive properties under heating, etc., and in adhesion to a polyolefin material. SOLUTION: A graft polymer having active hydrogen groups and formed by polymerizing a radical-polymerizable monomer having an active hydrogen group in the presence of a polyolefin copolymer and, if necessary, a tackifier in a thermally melting and kneading machine is reacted with a polyisocyanate compd. in an amt. higher than stoichiometrically needed based on the active hydrogen groups.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a reactive hot melt adhesive composition. More specifically, it relates to a novel reactive hot melt adhesive composition which is excellent in initial adhesion and adhesion durability.

[0002]

2. Description of the Related Art Reactive hot-melt adhesives have both instantaneous initial adhesive strength and durable adhesive strength such as heat resistance, and are used for applications requiring durability such as automobile interiors and floor materials. . Conventionally, the reactive hot melt adhesive is composed of, for example, a polyether urethane prepolymer, an ethylene-vinyl acetate copolymer and a tackifier (for example, JP-A-49-98445), polyester urethane. Those comprising a prepolymer and a tackifier (for example, JP-A-59-197482), those comprising a polyester urethane prepolymer, a saturated polyester resin, and a tackifier (for example, JP-A-7-17890). ) Is known.

[0003]

However, since the above-mentioned materials are polyether type prepolymers, they have poor cohesive strength and insufficient initial adhesive strength and heat resistance; Since it is a prepolymer, it has cohesive force, but it is hydrolyzed by hot water and its heat-resistant adhesive force becomes insufficient; In addition to being sufficient, it is not suitable for adhesion of polyolefin and the like.

[0004]

Means for Solving the Problems The present inventors have solved these problems and have good initial adhesiveness and durability such as heat resistance, and are also useful for adhering polyolefin resin molded articles and the like. As a result of extensive studies aimed at obtaining a reactive hot melt adhesive that can be used, a product obtained by reacting a polyisocyanate with a graft modified product of a specific polyolefin-based resin with an active hydrogen group-containing vinyl monomer has dramatically improved performance. The present invention has been achieved, and the present invention has been reached. That is, in the present invention, an active hydrogen group-containing radical-polymerizable monomer (B) is polymerized in a heating melt kneader in the presence of a polyolefin-based copolymer (A) and optionally a tackifier (a1). Reactive hot melt adhesive characterized by reacting an active hydrogen group-containing graft modified product (C) obtained by reacting the above with a polyisocyanate compound (D) in excess equivalent to the active hydrogen group of the (C). It is an agent composition.

As the polyolefin-based polymer (A) in the present invention, ethylene-butene copolymer, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, ethylene-propylene non-conjugated diene terpolymer,
Examples include α-olefin homopolymers and ethylene-α-olefin copolymers. Of these, preferred are ethylene-butene copolymers, ethylene-vinyl acetate copolymers and ethylene-α-olefin copolymers,
More preferably, it is an ethylene-vinyl acetate copolymer.

The active hydrogen group-containing radically polymerizable monomer (B) used for graft modification in the present invention includes
Examples thereof include a hydroxyl group-containing radically polymerizable monomer or its derivative (b1) and a carboxyl group-containing vinyl monomer or its derivative (b2). At least a part of the (B) is preferably (b1) from the viewpoint of reactivity with the polyisocyanate (D) described later.

A specific example of the above (b1) is, for example, 2
-Hydroxyethyl acrylate (HEA), 2-hydroxyethyl methacrylate (HEMA), 4-hydroxybutyl methacrylate, hydroxypropyl methacrylate, HEA or HEMA alkylene oxide polyadduct, (meth) acrylic acid caprolactone polyadduct, N- Hydroxymaleimide and mixtures of two or more thereof. Of these, preferred are HEA and HEMA, and more preferred is HEA in terms of thermal stability.

Specific examples of (b2) include vinyl group-containing carboxylic acids [(meth) acrylic acid, maleic acid, fumaric acid, itaconic acid, etc.], vinyl group-containing dicarboxylic acid monoesters and imidized products (maleimide). Etc.) and the like. Among these, (meth) acrylic acid and maleic acid are preferable.

Along with the active hydrogen group-containing radically polymerizable monomer (B), if necessary, a styrene compound, (meth)
Acrylonitrile, an epoxy group-containing monomer, and a radical polymerizable monomer (b3) having no active hydrogen group such as (meth) acrylic acid ester can be used in combination. Specific examples of the styrene compound include styrene, t-butylstyrene, α-methylstyrene, p-methylstyrene, chlorostyrene, bromostyrene, fluorostyrene, ethylstyrene, divinylbenzene, and N, N-diethylaminostyrene. . Particularly preferred among these is styrene.

Specific examples of the epoxy group-containing monomer include glycidyl methacrylate and allyl glycidyl ether. Besides this, methyl (meta)
Examples thereof include acid ester compounds such as acrylic acid esters and maleic acid dialkyl esters, alkyl and aralkyl (meth) acrylates such as cyclohexyl (meth) acrylate and benzyl (meth) acrylate, and imidized compounds such as N-methylmaleimide. Among these, preferable are (meth) acrylic acid alkyl esters and maleic acid dialkyl ester compounds.

In the present invention, the weight ratio of (A) :( B) is usually 100: (1-100), preferably 100 :.
(5 to 80), more preferably 100: (10 to 5)
0). If the ratio of (B) is less than 1, the adhesive strength and heat resistance will be insufficient, and if it exceeds 100, the final composition will have a high viscosity and the workability when used as a reactive hot melt adhesive will be deteriorated. In addition, (b) in (B)
The weight ratio of 1) :( b2) :( b3) is usually (1 to 4).
0): (0 to 30): (0 to 30), preferably (3 to
40): (0-30): (0-30), and more preferably (5-60): (0-20): (0-20).
When the ratio of (b1) + (b2) is less than 1, the strength and heat resistance are significantly reduced.

Examples of the polyisocyanate compound (D) in the present invention include tolylene diisocyanate (T
DI), 4,4'-diphenylmethane diisocyanate (MDI), polymethylene polyphenyl polyisocyanate (Polymec MDI), 1,4'-phenylenediisocyanate (PPDI), α, α, α ', α'-tetramethylxylylenediene Isocyanate (TMXDI),
4,4'-Dicyclohexylmethane diisocyanate (H12MDI), cyclohexane diisocyanate (C
HDI), 1,6-hexamethylene diisocyanate (HMDI), isophorone diisocyanate (IPD
I), modified products of these diisocyanates, and mixtures of two or more thereof. Of these, preferred are MDI and TDI, and more preferred is MDI.

In the present invention, the equivalent ratio of the active hydrogen groups in the graft modified product (C) and the isocyanate groups in (D) is usually 1: (1.8 to 4), preferably 1: (1.8).
~ 3) More preferably 1: (1.9-2.5). When the equivalent ratio of the isocyanate is less than 1.8, the heat resistance strength is lowered, and the crosslinking reaction by the polyisocyanate causes the final composition to have a high viscosity so that the workability is lowered. On the other hand, when it exceeds 4, the heat resistance is lowered, and unreacted (D) is exposed to high temperature to generate toxic vapor, which deteriorates the working environment.

In the present invention, a tackifier (a1) may be contained for the purpose of further improving the initial adhesiveness. In the step of adding the (a1), a part or all of the (a1) is added to (A) in advance for graft modification; (a1) is added to the graft-modified product (C);
After the reaction of the graft modified product (C) and (D), (a1) is added later; and the like. Among these, the method of and is preferable, and the method of is more preferable. As the tackifier (a1), a terpene resin or its derivative (for example, a terpene-styrene copolymer resin, a terpene phenol copolymer resin), an aliphatic hydrocarbon resin (1,3 pentadiene, dicyclopentadiene, etc.) , Aromatic hydrocarbon resins or copolymer resins thereof, and rosin derivatives (esterified, maleated abietic acid type rosin derivatives, etc.). Among these, preferred are terpene resins and rosin derivatives from the viewpoint of compatibility.

The amount of tackifier (a1) in the present invention is usually 0 to 80% by weight, preferably 15 to 70% by weight, more preferably 2 based on the total weight of the adhesive composition.
5 to 60% by weight. If it exceeds 80% by weight, the strength and heat resistance of the adhesive are impaired.

The method for producing the composition of the present invention is not particularly limited, but, for example, after (D) is reacted with (C) obtained by graft-polymerizing (B) in the presence of (A) in advance, ( a1) is mixed; (B) is polymerized in the presence of (A) and (a1) is mixed with (D); and (B) is added in the presence of (A). A method of reacting (D) with a polymer and a polymer of (B) in the presence of (a1); (D) to a polymer of (B) in the presence of (A) and (a1). Examples include a method of reacting (A1) with (B) polymerized and a method of reacting (A) with (D).
Among these, the methods of and are preferred, and the methods of and are more preferred.

A known polymerization initiator can be used for the graft polymerization, if necessary. The polymerization initiator, ketone peroxide, peroxyketal, hydroperoxide, dialkyl peroxide, diacyl peroxide, organic peroxides such as peroxydicarbonate and azo compounds such as azoisobutyronitrile and these Two or more types may be used in combination. As the polymerization initiator, one that is particularly easily dissolved in the radically polymerizable monomer (B) is appropriately selected and used. The amount of the polymerization initiator is (B) 100.
It is usually 0.05 to 5 parts by weight, preferably 0.1 to 2 parts by weight, based on parts by weight. The graft polymerization reaction is usually performed without a solvent, but an organic solvent may be used if necessary. Examples of the organic solvent include alicyclic hydrocarbon solvents, aromatic hydrocarbon solvents, alcohol solvents, halogen solvents, ketone solvents, ether solvents and the like.

The temperature of the graft polymerization is not particularly limited as long as it is a temperature at which the monomer is substantially polymerized, but a temperature at which the half-life of the polymerization initiator is less than 1 minute is preferable, and usually 8
It is 0 to 260 ° C, preferably 120 to 220 ° C.
The graft polymerization time is usually 5 to 60 minutes, preferably 10 to 40 minutes.

For the reaction of the modified graft product (C) containing an active hydrogen group and the polyisocyanate (D), a known urethanization catalyst can be used if necessary. Examples of the catalyst include organometallic compounds (cobalt naphthenate, dibutyltin laurylate, trimethyltin hydroxide, etc.), amines (triethylenediamine, tetramethylbutanediamine), and combinations of two or more thereof. The amount of the catalyst used is usually 0.001 to 1 part by weight, preferably 0.01 to 0.8, per 100 parts by weight of (D).
Parts by weight.

The temperature of the reaction of the above (C) and (D) is not particularly limited as long as it is a temperature at which the (C) and (D) substantially react with each other, but it is usually from -20 to 200 ° C, preferably. Is 20
~ 150 ° C. The reaction time is usually 5 to 60.
Minutes, preferably 10 to 40 minutes.

The heating and melting kneader used for the graft polymerization and urethanization reaction is not particularly limited in mode, shape and the like, but for example, a plastomill, a kneader, a screw having a highly compressible shape having a reverse threaded portion. Alternatively, a mixer having a stirrer, Kolben, or the like can be given.

In the reactive hot melt adhesive composition of the present invention, various known additives such as wax (paraffin wax, low molecular weight polyolefin wax, etc.), antioxidant, Fillers, plasticizers, pigments, lubricants, etc.] can be added.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described more specifically with reference to Examples, but the present invention is not limited to these Examples. In addition, the part in an Example shows a weight part and% shows weight%. The reactions of the following Examples 1 to 7 and Comparative Example 1 were carried out in a plastomill under constant stirring at 60 rpm.
It was conducted under nitrogen flow.

[0024]

【Example】

Example 1 28 parts of ethylene-vinyl acetate copolymer (EVA, vinyl acetate content 19 wt%) was completely melted at 100 ° C. for 30 minutes. "Perbutyl Z" (tert-butyl peroxybenzoate, manufactured by NOF Corporation) 0.035
2-hydroxyethyl acrylate (H
7 parts of EA) was added, the temperature was raised to 170 ° C., and the reaction was carried out for 30 minutes to obtain an active hydrogen group-containing graft modified product (C-1).
35 parts of the (C-1) and a tackifier "TR-105" 5
What was melt-kneaded with 0 parts at 100 ° C. for 30 minutes was
DI 15 parts [double equivalent to active hydrogen of (C-1)]
And 0.002 part of dibutyltin dilaurylate as a urethane-forming catalyst were added and reacted for 30 minutes to obtain an adhesive composition. The obtained adhesive composition was subjected to demomerization in a vacuum constant temperature dryer (manufactured by Yamashita Seisakusho) at 5 mmHg and 150 ° C. for 2 hours to obtain a reactive hot melt adhesive composition of the present invention.

Examples 2 to 7 Reactive hot melt adhesive compositions of the present invention were obtained in the same manner as in Example 1 according to the formulations shown in Table 1. In Examples 1 to 3, graft modification was carried out only on the polyolefin polymer, and in Examples 4 to 7, graft modification was carried out in the presence of the tackifier together with the polyolefin polymer.

[0026]

[Table 1]

(Explanation of symbols) EVA: ethylene-vinyl acetate copolymer (melt viscosity at 190 ° C. 15000 cP, vinyl acetate content 19 wt%,
Mitsui DuPont Chemical's "EV410") APAO; α-polyolefin (melt viscosity at 190 ° C 3
500 cP, “UT2535” manufactured by Ube Lexen) EBM; ethylene-butene copolymer (melt viscosity at 190 ° C., 35000 cP, butene content 13 wt%, “Esprene EBMN0377” manufactured by Sumitomo Chemical Co., Ltd.) ST; Styrene HEA; 2-hydroxy Ethyl acrylate (manufactured by Nacalai Tesque, Inc.) TR; tackifier (terpene resin with a softening point of 105 ° C., Yasuhara Chemical Co. “TR-105]) Quinn; tackifier (petroleum resin with a softening point of 100 ° C., Japan "Quinton R-100" manufactured by Zeon Co., Ltd.) MDI; 4,4'-diphenylmethane diisocyanate (manufactured by Nippon Polyurethane Industry Co., Ltd.)

Comparative Example 1 24 parts of EVA and 8 parts of EBM were melt-kneaded at 100 ° C. for 30 minutes. To this was added ST8 part in which 0.08 part of dicumyl peroxide was completely dissolved, and the temperature was raised to 170 ° C.,
The reaction was performed for 30 minutes. TR to 40 parts of this modified graft
60 parts were melt-kneaded at 100 ° C. for 30 minutes to obtain a comparative hot melt adhesive.

Comparative Example 2 A commercially available reactive hot melt adhesive (“170-7141” manufactured by Kanebo NSC Co., Ltd.) was used as it was.

Performance Test Examples The reactive hot melt adhesive compositions obtained in Examples 1 to 7 and Comparative Examples 1 and 2 were each subjected to the following melt viscosity measurement, initial adhesion, adhesion after curing, and heat resistance. The adhesiveness and the T-type peeling adhesive strength were measured. Table 2 shows the results.

[0031]

[Table 2] (Measurement method) Melt viscosity: Viscosity by B-type viscometer at 150 ° C. Preparation of adhesive strength test piece; 100 g / cm on both sides of a 25 mm square adhesive surface, using dried birch wood with a water content of 15% or less. ² was applied and pressure-bonded at 80 ° C. under a load of 5 kg / cm ² for 3 minutes. Initial adhesive strength: Immediately after bonding the adhesive strength test piece,
3 mm / min in an atmosphere of temperature 23 ° C and humidity 60%
Measure the maximum load at break at a shear rate of 10
The average value is shown. Adhesive strength after curing: The above adhesive strength test piece was allowed to stand for 1 week in a constant temperature and constant temperature chamber (23 ° C., 60% RH), and the test piece was measured under the same conditions as the above initial adhesive strength. Heat-resistant adhesive strength; test piece used in adhesive strength 4 in boiling water
After soaking for 20 hours, dry at a temperature of 60 ± 3 ℃ for 20 hours,
Further, what was immersed in boiling water for 4 hours was measured for the maximum load at break at a shear rate of 3 mm / min in a wet state, and the average load of 10 pieces was shown. T-type peeling adhesive strength; each adhesive was applied to a biaxially oriented polypropylene film at 25 mm × 25 mm and a thickness of 100 μm, and the polypropylene film was pressure bonded under the conditions of 80 ° C. × 10 seconds × 1 kg / cm ² T under conditions of 23 ° C, humidity of 60%, and pulling speed of 300 mm / min
The mold peel adhesion strength was measured.

[0032]

The reactive hot melt adhesive composition of the present invention has the following effects. (1) Excellent reactivity such as heat resistance peculiar to the reactive hot melt adhesive. (2) The reactive hot melt adhesive is particularly excellent in poor initial adhesive strength. (3) Excellent adhesion to various materials. Particularly, it exhibits excellent adhesiveness even to polyolefin resins such as polypropylene, which are difficult to adhere to. (4) Excellent workability due to low viscosity. Due to the above effects, the reactive hot melt adhesive comprising the composition of the present invention can be used for flooring and interior parts of automobiles requiring heat resistance, and also has low viscosity and long open time. Therefore, it can be used in a wide variety of applications such as complicated lines and adhesion of a large area, and is extremely useful industrially.

Claims (5)

[Claims] 1. An active hydrogen group-containing radical-polymerizable monomer (B) is polymerized in a heating melt kneader in the presence of a polyolefin-based copolymer (A) and optionally a tackifier (a1). Modified graft containing active hydrogen group (C)
And a polyisocyanate compound (D) in an excess equivalent amount with respect to the active hydrogen groups of (C), a reactive hot melt adhesive composition. 2. The adhesive composition according to claim 1, wherein the equivalent ratio of the active hydrogen group in (C) and the isocyanate group in (D) is 1: (1.8 to 4). 3. (A) is an ethylene-butene copolymer,
At least one selected from the group consisting of ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, ethylene-propylene non-conjugated diene terpolymer, α-olefin homocopolymer and ethylene-α-olefin copolymer. The adhesive composition according to claim 1 or 2. 4. The adhesive composition according to claim 1, wherein (B) essentially contains a hydroxyl group-containing radically polymerizable monomer. 5. The adhesive composition according to claim 1, wherein the amount of (B) is 1 to 100 parts by weight per 100 parts by weight of (A).