CN1311047C - Adhesive composition and method of bonding - Google Patents

Abstract

An adhesive with which polyolefin resins can be bonded while attaining a high initial bond strength and which has excellent adhesion durability especially at high temperatures. The adhesive is an adhesive composition comprising: a liquid composition obtained by dissolving or dispersing a carboxylated thermoplastic elastomer (A), a polyolefin polyol (B), and a tackifier (C) in an organic solvent; and a polyfunctional isocyanate (D). Preferably, the ratio of the weight of the carboxylated thermoplastic elastomer (A) to that of the polyolefin polyol (B) in the liquid composition is from 98/2 to 20/80 and the amount of the tackifier (C) is 5 to 150 parts by weight per 100 parts by weight of the sum of the ingredients (A) and (B).

Description

Adhesive composition and bonding method

technical field

The present invention relates to a two-component liquid adhesive composition, and more specifically, to a two-component adhesive having high initial bond strength, final bond strength, and good bond durability for bonding polyolefin resins. Mixture composition.

Background technique

In general, polyolefin resins such as polyethylene and polypropylene are known to be difficult to bond with an adhesive. However, many proposals have been made regarding adhesives applicable to such polyolefin resins. Specifically, a thermoplastic elastomer such as a copolymer obtained by hydrogenating a styrene/isoprene/styrene block copolymer or a styrene/butadiene/styrene block copolymer as a main component has been proposed. Solutions for hot melt adhesives.

In Japanese Patent Application Laid-Open No. 62-48779 (claims), a hot-melt type adhesive comprising the above-mentioned thermoplastic elastomer, hydrocarbon resin tackifier, wax, and hydrocarbon synthetic rubber having a pour point of 120° C. or less is disclosed. The agent is suitable for the bonding of polyolefins. In addition, Japanese Patent Laid-Open No. 3-259981 (claims) discloses the cohesion and cohesion at high temperature of an isocyanate prepolymer obtained by reacting the same thermoplastic elastomer with hydroxyl-containing polyisoprene and isocyanate. A hot melt adhesive with improved solvent resistance, etc. Such a hot-melt adhesive is solvent-free and relatively easy to coat the substrate, so it is practical, but the adhesive strength needs to be further improved.

Contents of the invention

An object of the present invention is to provide an adhesive capable of bonding polyolefin resins with high initial adhesive strength and excellent in adhesion durability, especially adhesion durability at high temperatures.

The present invention is a liquid composition comprising a carboxyl group-containing thermoplastic elastomer (A), a polyolefin polyol (B) and a tackifier (C) dissolved or dispersed in an organic solvent, and a polyfunctional isocyanate (D). Adhesive composition.

In the preferred adhesive composition of the present invention, the mass ratio of the carboxyl-containing thermoplastic elastomer (A) to the polyolefin polyol (B) in the above-mentioned liquid composition is 98/2 to 20/80, and the above-mentioned The ratio of the thickener (C) is 5 to 150 parts by mass per 100 parts by mass of the total amount of (A) and (B).

In the preferred composition for holographic recording of the present invention, the carboxyl group-containing thermoplastic elastomer (A) is a carboxyl group-containing styrene-based thermoplastic elastomer.

In the present invention, a thermoplastic elastomer having a carboxyl group, that is, a carboxyl group-containing thermoplastic elastomer is used. In the present invention, the so-called thermoplastic elastomer refers to a resin whose molded product has rubber elasticity at room temperature even without vulcanization treatment, that is, a substance that becomes a thermoplastic resin and has rubber elasticity, and generally has an ABA type block in the chemical structure. Or (A-B) n-type multi-block structure copolymer.

The carboxyl group-containing thermoplastic elastomer in the present invention is obtained by introducing a carboxyl group into a thermoplastic elastomer. Specific examples of preferred thermoplastic elastomers include styrene-butadiene block copolymers, styrene-ethylene-propylene block copolymers, styrene-butadiene-styrene block copolymers, styrene - Isoprene-styrene block copolymer, styrene-ethylenebutylene-styrene block copolymer, styrene-ethylenepropylene-styrene block copolymer, ethylene-propylene copolymer, ethylene-propylene meta-copolymer. Hereinafter, block copolymers having polystyrene units are referred to as styrene-based elastomers.

As a method of introducing a carboxyl group into the thermoplastic elastomer, a method of copolymerizing an appropriate amount of an ethylenically unsaturated carboxylic acid such as maleic acid is usually used when polymerizing monomers used to produce the thermoplastic elastomer. For example, in the case of styrene-based elastomers such as styrene-isoprene-styrene block copolymers, carboxyl groups can be introduced into the elastomer by copolymerizing maleic acid when polymerizing styrene monomers (hereinafter , introducing a carboxyl group into an elastomer is called acid modification).

In the present invention, since the solubility in the organic solvent used is good, it is preferable to introduce a carboxyl group into the styrene-based elastomer.

A particularly preferred carboxyl-containing thermoplastic elastomer in the present invention is a maleic acid-modified styrene-based elastomer, which is a maleic acid-modified styrene-based elastomer containing 5 to 65% by mass, preferably 10 to 40% by mass, of styrene units in the copolymer. Styrenic elastomer. As a specific example, Claiton produced by Claiton Polymer Co., Ltd. and TuftecM series produced by Asahi Kasei Industry Co., Ltd. can be mentioned. The skeleton of these products is styrene-ethylene-butylene-styrene block copolymer (hereinafter referred to as SEBS). .

The polyolefin polyol in the present invention has the same saturated hydrocarbon skeleton as the low molecular weight polyolefin, and has a plurality of hydroxyl groups. Its molecular weight is preferably in the range of 500-5000. If the molecular weight is above 5000, it is hardly soluble in organic solvents; if the molecular weight is below 500, the adhesion of the obtained adhesive composition to polyolefin resins will easily decrease. Specific examples of preferable polyolefin polyols include Polytel (trade name) produced by Mitsubishi Chemical Corporation.

The preferable usage ratio of the above-mentioned thermoplastic elastomer and the polyolefin polyol is, in terms of mass ratio, 98/2-20/80, more preferably 90/10-40/60. When the proportion of the polyolefin polyol is less than 2 in mass ratio, adhesion durability cannot be achieved, and on the other hand, if it exceeds 80, the adhesion strength tends to decrease.

Examples of the tackifier in the present invention include polyterpene-based resins, rosin-based resins, aliphatic petroleum resins, alicyclic petroleum resins, copolymer-based petroleum resins, and hydrogenated petroleum resins. Among them, in the present invention, hydrogenated hydrocarbon resins are preferable in terms of adhesion durability.

Specific examples of polyterpene-based resins include α-pinene polymers, β-pinene polymers, and copolymers of these polymers with phenol or bisphenol A. Commercially available products of these resins include Yasuhara Chemical Co., Ltd. The trade names produced by the company are YS ResinPX, YS ResinA, YS PolystarT, etc.

Examples of rosin-based resins include natural rosin, polymerized rosin and ester derivatives thereof, and examples of commercially available products include Pensel D and SuperEster A produced by Arakawa Chemical Industry Co., Ltd.

Aliphatic petroleum resins are resins usually synthesized from C5 fractions of petroleum, which are also called C5 types. As commercially available products, there are Esukotsu produced by Tonex Co., Ltd., Quinton produced by Japan Zeon Co., Ltd., and Good Year Co., Ltd. Wingtac et al.

Alicyclic petroleum resins are generally resins synthesized from C9 fractions of petroleum, and examples of commercially available products include Maruzen Petrochemical Co., Ltd., and the like.

The copolymerized petroleum resin is also called C5/C9 copolymerized resin, and commercially available products include Toho High Resin produced by Toho Chemical Industry Co., Ltd., and the like.

The hydrogenated petroleum resin is a resin obtained by hydrogenating the above-mentioned tackifier resin. Commercially available products include ester rubber H and Alcom produced by Arakawa Chemical Industry Co., Ltd., Clearon produced by Yasuhara Chemical Co., Ltd., and Tonex Co., Ltd.エスコツツ and others.

The preferred usage amount of the tackifier is 5 to 150 parts by mass, more preferably 20 to 100 parts by mass, based on 100 parts by mass of the total amount of the carboxyl group-containing thermoplastic elastomer and polyolefin polyol. If the amount of the tackifier used is less than 5 parts by mass, the adhesiveness will decrease and sufficient adhesive strength cannot be achieved, and if it exceeds 150 parts by mass, the adhesion durability will tend to be insufficient.

The preferred organic solvent used in the present invention is a solvent that dissolves or disperses the above-mentioned components, has appropriate volatility, and has no reactivity with isocyanate groups. Specifically, toluene, n-hexane, xylene, cyclohexane, Methylcyclohexane and methyl ethyl ketone, etc.

In the liquid composition containing each of the above components and an organic solvent, the solid content concentration is preferably 5 to 50% by mass, more preferably 10 to 40% by mass.

In the present invention, a liquid composition containing the above-mentioned components and an organic solvent and a polyfunctional isocyanate are used in combination. That is, the adhesive composition of the present invention is a composition utilizing an isocyanate curing reaction, and the amount of polyfunctional isocyanate used is preferably such that the molar ratio (NCO/OH) of the isocyanate group relative to the hydroxyl group in the polyolefin polyol is The amount in the range of 1.0 to 10.0 is more preferably the range in which the molar ratio is 1.2 to 8.0. When NCO/OH is less than 1.0, the adhesion durability decreases, and when it exceeds 10.0, the adhesion strength tends to decrease.

The mixing of the liquid composition and the polyfunctional isocyanate is usually preferably carried out immediately before the adhesive is used. After mixing these two components, if left as it is for a long period of time, phenomena such as gelation will occur, making it unusable as an adhesive. The time that can be used as an adhesive after mixing is called usable time (shelf life). The shelf life of the adhesive composition of the present invention varies from several minutes to several hours depending on the type of compound used.

Examples of the polyfunctional isocyanate used by mixing with other components immediately before use as described above include toluene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, and isophorone diisocyanate. , and isocyanurate modification, biuret modification, trimethylolpropane and other addition compound modifications, etc. Specifically, CORONET HX produced by Nippon Polyurethane Industry Co., Ltd., which belongs to isocyanurate modification, and Takenate D-170N produced by Mitsui Takeda Chemical Co., Ltd., etc., and Takenate D-165N, which belongs to biuret modification, can be mentioned. , CORONET L, TAKENATE D-102 and TAKENATE D-140N, which are modified trimethylolpropane addition compounds.

In the present invention, the blocked polyfunctional isocyanate stabilized by blocking the isocyanate group with a blocking agent can also use, for example, CORONET 2507 and CORONET 2513 produced by Nippon Polyurethane Industry Co., Ltd. The mixing time of the functional isocyanate is not particularly limited. That is, since one liquid has a long-term shelf life, it is also possible to manufacture the adhesive as one liquid.

In the pressure-sensitive adhesive composition of the present invention which contains the above-mentioned various components as essential components, other components may be added. For example, in order to accelerate the reaction between polyolefin polyol and polyfunctional isocyanate, reaction accelerators such as organotin compounds, plasticizers, and thermoplastic resins (including elastomers) that do not belong to the above-mentioned components (A) to (C) can be added. . As such a thermoplastic resin, ethylene-vinyl acetate copolymer resin, ethylene-ethyl acrylate copolymer resin, wax, SEBS or SEPS are preferable. Examples of preferable plasticizers include liquid rubbers such as polyisoprene and polybutene, processing oils, and the like.

When bonding substrates with the adhesive composition of the present invention, an adhesive layer of 3 to 30 μm is formed (dried) on the surface of the substrate, and other substrates to be bonded are preferably bonded by heating and pressing. material operation. The heating temperature at this time is preferably 60 to 150°C. The substrate bonded in this way is preferably left in an environment of 50 to 80° C. for several days to accelerate the reaction between the polyolefin polyol and the polyfunctional isocyanate.

If the adhesive composition of the present invention is used, polyolefin resin substrates such as polyethylene and polypropylene can be bonded with high strength, and it can also be used for bonding these materials with other materials. For example, polyolefin-based materials can be easily bonded to resins such as polyethylene terephthalate or metal surfaces such as aluminum and copper after applying the adhesive.

Detailed ways

Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples.

(Example)

Example 1

In the 500ml flask that condenser and stirring device are equipped with, add 225g as the toluene/methyl ethyl ketone=80/20 of solvent, 45g are produced as the Tuftec M-1913 ( SEBS, styrene content 30% by weight), 5 g of PolytelH (molecular weight 3000) produced by Mitsubishi Chemical Corporation as a polyolefin polyol, 25 g of Escot 5320HC (hydrogenated dicyclopentadiene) produced by Tonex Co., Ltd. as a tackifier Vinyl resin, softening point 125°C), with respect to the total amount of the above-mentioned thermoplastic elastomer, polyolefin polyol, and tackifier, add 50 ppm of dibutyltin dilaurate (hereinafter referred to as DBTL) as a reaction accelerator, in It heat-stirred at internal temperature 50 degreeC for 3 hours, and obtained the composition.

CORONET HX produced by Nippon Polyurethane Industry Co., Ltd. as a polyfunctional isocyanate was mixed with the above composition cooled to room temperature so that the molar ratio (NCO/OH) of the isocyanate group to the hydroxyl group of the polyolefin polyol was 2.0 to obtain an adhesive combination.

The obtained adhesive composition was adhered according to the following method, and its adhesive strength was evaluated.

○Adhesion: Coat the adhesive solution on one side of aluminum or polyethylene terephthalate with a thickness of 100 μm, so that the thickness of the dried coating film is 10 μm, and dry at 100°C×60 seconds. On the adhesive coated surface, a 40 μm thick CPP (unstretched polypropylene) film was superimposed, heated and pressed at 80°C for 3 seconds, and aged at 55°C for 7 days.

○Measurement of adhesive strength: Measure the 180°peel adhesive strength (N/15mm) at 23°C and 80°C at a cross head speed of 100mm/min.

○ Adhesive durability: In an environment of 150mm ² (15mm wide x 10mm overlapping) and 100°C, apply a shear load of 1kg, and observe the state of the bonded part after leaving it for 24 hours.

Embodiment 2-7

The solvent, carboxyl-containing thermoplastic elastomer, polyolefin polyol, tackifier, DBTL and multifunctional isocyanate were used in the proportions shown in Table 1 to obtain an adhesive composition. The obtained adhesive composition was evaluated similarly to Example 1, and Table 1 shows the result. On the other hand, in the evaluation results related to adhesion durability, the adhesives of Examples 1 to 7 were all "no change".

In addition, details of the compounds described in Table 1 are as follows.

Claiton FG-1901X: Carboxyl-containing thermoplastic elastomer produced by Claiton Polymer Co., Ltd. (SEBS type, styrene content is 30% by mass);

Tuftec M-1943: Elastomer produced by Asahi Kasei Industry Co., Ltd. (SEBS type, styrene content is 20% by mass);

Polytel HA: polyolefin polyol produced by Mitsubishi Chemical Corporation (molecular weight 2000);

Clearon P-85: Tackifier produced by Yasuhara Chemical Co., Ltd. (hydrogenated terpene resin, softening point 85°C);

Wingtac10: Tackifier produced by Good Year Company (aliphatic C5 petroleum resin, softening point 10°C);

CORONET L: Multifunctional isocyanate produced by Japan Polyurethane Industry Co., Ltd.

In addition, in Table 1, the units of numerical values with units omitted are parts by mass, Al/CPP is a test piece using aluminum and unstretched polypropylene, and PET/CPP is a test piece using polyethylene terephthalate and Test piece of unstretched polypropylene.

Comparative example 1

340 g of toluene/methyl ethyl ketone=80/20, 50 g of Claiton FG-1901X, and 35 g of Clearon P-85 were added, and heated and stirred at an internal temperature of 50° C. for 3 hours to obtain an adhesive composition. Next, the physical properties of the adhesive composition were evaluated in the same manner as in Example 1, and Table 2 shows the results.

Comparative example 2-4

The physical properties of the adhesive composition obtained by blending each component described in Table 2 were evaluated, and Table 2 shows the results. In addition, the thermoplastic elastomer Claiton G-1652 used in Comparative Example 2 is a thermoplastic elastomer (SEBS type) not containing a carboxyl group.

Among the adhesives of the respective comparative examples described above, the evaluation result of the adhesion durability of the adhesive of Comparative Example 1 was "peeling". The adhesion durability of the adhesives of other comparative examples was "no change".

Table 1 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 (A) Tuftec M-1913 90 60 40 60 60 - - Claiton FG-1901X - - - - - 60 - Tuftec M-1943 - - - - - - 60 (B) Polytel H 10 - 30 - - - - Polytel HA - 40 30 40 40 40 40 (C) エスコツツ5320HC 50 50 50 - - 50 50 Clearon P-85 - - - 20 - - - Wingtac10 - - - - 80 - - Solvent (toluene/MEK) 450 450 450 360 5l0 450 450 DBTL(ppm) 50 50 50 50 50 50 50 (D) CORONET HX (NCO/OH molar ratio) 2.0 3.0 1.5 4.5 3.0 3.0 3.0 Adhesive Strength (N/15mm) AL/CPP 23℃ 9.2 8.6 7.0 7.5 6.1 9.0 7.8 AL/CPP 80℃ 4.1 1.3 1.0 1.2 1.0 1.2 1.0 PET/CPP 23℃ 12.9 3.9 4.1 3.5 3.5 4.2 3.7 PET/CPP 80℃ 3.4 3.0 2.9 2.8 2.5 2.8 2.5

Table 2 Comparative example 1 Comparative example 2 Comparative example 3 Comparative example 4 (A)Tuftec FG-1901X 100 - 60 - Claiton G-1652 - 60 - - (B) Polytel H - - 40 - Polytel HA - 40 - 100 (C) Clearon P-85 70 20 - 50 Solvent (toluene/MEK) 510 480 400 450 DBTL(ppm) - 50 50 50 (D) CORONETHX (NCO/OH molar ratio) - 3.0 3.0 3.0 Adhesive strength (N/15mm) AL/CPP 23°C 7.4 2.4 3.3 4.1 AL/CPP 80℃ 0.7 0.4 0.3 0.3 PET/CPP 23℃ 6.6 2.1 2.3 5.0 PET/CPP 80℃ 2.5 0.2 0.1 0.1

Industrial Utilization Possibility

The adhesive composition of the present invention can adhere polyolefin resins with high strength.

Claims (4)

1. an adhesive composition, is characterized in that, contains A liquid composition in which a carboxyl group-containing thermoplastic elastomer (A), a polyolefin polyol (B) and a tackifier (C) are dissolved or dispersed in an organic solvent, and a polyfunctional isocyanate (D), The molecular weight of the polyolefin polyol (B) is 500-5000. 2. adhesive composition as claimed in claim 1, is characterized in that, the mass ratio of the carboxyl-containing thermoplastic elastomer (A) and polyolefin polyol (B) in the liquid composition is 98/ 2 to 20/80, and the ratio of the total amount of (A) and (B) per 100 parts by mass of the tackifier (C) is 5 to 150 parts by mass. 3. The adhesive composition according to claim 1 or 2, wherein the carboxyl group-containing thermoplastic elastomer (A) is a carboxyl group-containing styrene-type thermoplastic elastomer. 4. A method for bonding polyolefin-based substrates, characterized in that the adhesive composition according to any one of claims 1 to 3 is used.