JPS6228836B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a block copolymer-modified thermoplastic adhesive resin comprising a conjugated diene and an aromatic vinyl, which has excellent adhesive properties and moldability at high temperatures. Block copolymers of aromatic vinyl and conjugated diene, particularly block copolymers of styrene as the aromatic vinyl and butadiene or isoprene as the conjugated diene, are useful as polymers with excellent adhesiveness and tackiness at room temperature. However, a major drawback is that the adhesive strength is low at high temperatures, and there are also drawbacks in terms of water resistance and oil resistance at high temperatures. The present invention provides an adhesive resin that overcomes these drawbacks and a method for producing the same, and its gist is that A is an aromatic vinyl polymer block and B is an aromatic vinyl polymer block.
is substantially a conjugated diene polymer block, m is 1
An integer from 2 to 2, n an integer from 2 to 8, and X a n
It is represented by the general formula (A-B) _-n A or (A-B) _o 10 to 70% by weight, and further 175℃, 2.5×
Melt viscosity under shear stress of 10 ⁶ dyne/cm ² is 7.0×
Linear or branched block copolymers in the range of 10 ² to 6.0×10 ⁴ poise or mixtures thereof
100 parts by weight of maleic anhydride compound in solution state in the presence of 0.1 to 5 parts by weight of a radical generator.
After maleation reaction with 0.5 to 15 parts by weight, 1
Adding 0 to 10 parts by weight of at least one selected from oxides, hydroxides, organic acid salts, and alkoxides of valent or divalent metals, and reacting the modified copolymer solution before or after addition of the metal compound. Pour into a non-solvent and solidify to obtain a melt viscosity of 1.0×10 ³ to 1.0× under a shear stress of 4.0×10 ⁶ dyne/cm ² at 175°C.
This is a method for producing a thermoplastic adhesive resin characterized by obtaining a resin having a poise of 10 ⁵ . The present invention will be explained in detail below. The block copolymers constituting the present invention are limited to those represented by the above general formula. As block copolymers other than the above general formula, (A-B) _o , B
(-A-B) _o , etc., but if n is small, the adhesiveness at high temperatures is poor, and if n is large, manufacturing is not easy, which is not preferred. As the conjugated diene constituting linear block copolymer (A-B) _-n A or branched block copolymer (A-B) _o X, for example, butadiene, isoprene, 2,3-dimethylbutadiene, etc. are used. is,
As the aromatic vinyl, for example, styrene, vinyltoluene, tert-butylstyrene, vinylnaphthalene, etc. are used. Among them, preferred A-B
The combination is butadiene and styrene or isoprene and styrene. Further, as a polyfunctional binder that binds X constituting (A-B) _o , that is, n polymer chains, for example, Br(CH ₂ ) nBr (n = 1
~4), COCl ₂ ,

[Formula] Dehalogenated residue of bifunctional binder such as ClCH ₂ OCH ₂ Cl, (CH ₃ ) ₂ SiCl ₂ ,

【formula】

[Formula] SnCl ₄ ,

【formula】

These include dehalogenated residues of polyfunctional binders such as [Formula]. In the block copolymer (A-B) _o X, n must be in the range of 2 to 8. This is because manufacturing is not easy when n is 9 or more. Therefore, for (A-B) _o X, for example, A-B-X
-B-A,

【formula】

[Formula] etc. The content of aromatic vinyl in the block copolymer should be in the range of 10 to 70% by weight, preferably in the range of 12 to 50% by weight. This is because when the amount is less than the above range, the cohesive force becomes weak and cohesive failure is likely to occur, and when it is more than the above range, the adhesiveness decreases. Furthermore, the block copolymer was heated at 170℃, 2.5×
Melt viscosity under shear stress of 10 ⁶ dyne/cm ² is 7.0×
10 ² to 6.0×10 ⁴ poise, more preferably 1.0×10 ³
It is desirable that the amount is in the range of 4.0×10 ⁴ poise to 4.0×10 4 poise. This is because if it is smaller than this range, adhesiveness at high temperatures will be insufficient, and if it is larger than this range, moldability will tend to be poor. In the present invention, 100 parts by weight of such a block copolymer or block copolymer mixture is dissolved in a molten state or in a solvent, preferably 0.1 to 5 parts by weight of a radical generator. First, a maleation reaction is carried out with 0.5 to 15 parts by weight of a maleic anhydride compound in the presence of a maleic anhydride compound. The maleic anhydride compound referred to in the present invention has the general formula It is a compound represented by R, for example, H,
CH ₃ , phenyl, etc. are particularly preferably used, and one type or a mixture of one or more types is used. Therefore, the maleation reaction referred to in the present invention does not simply refer to a reaction with maleic anhydride, but refers to a reaction with any of these compounds. When the reaction is carried out in a dissolved state, a solvent that dissolves the copolymer and is inert to the maleic anhydride compound is used, such as aromatic hydrocarbons such as benzene, toluene, and xylene, cyclohexane, and decalin. Alicyclic hydrocarbons and the like are used. There is no particular restriction on the concentration of the solution, but it is usually 1 to 30% by weight. The radical generator is used in an amount of 0.1 to 5 parts by weight per 100 parts by weight of the block copolymer in order to allow the reaction between the block copolymer and maleic anhydride to proceed smoothly at a relatively low temperature. Peroxides such as benzoyl peroxide, di-tertiary butyl peroxide, and para-menthane hydroperoxide, and diazo compounds such as azobisisobutyronitrile are used as radical generators, and the reaction temperature is in a dissolved state. When reacting, a temperature of 60°C to 150°C is usually used. Also, when reacting in a molten state, it is 150 to 220
°C is used. The amount of maleic anhydride compound used is 0.5 to 15 parts by weight. If it is less than 0.5 parts by weight, the effect of maleation will be small, and if it is more than 15 parts by weight, the melt viscosity of the product will become too high due to covalent crosslinking that occurs simultaneously with maleation. At the stage of this maleated block copolymer, the adhesion at high temperatures is already improved compared to the original block copolymer. This maleated product can be used as a heat-resistant adhesive as it is, but the clear water structure in the polymer can be converted into a dicarboxylic acid by, for example, hot water treatment or alkali treatment followed by acid treatment. Good adhesive strength at high temperatures can be obtained by creating an open structure, or by reacting an anhydride or dicarboxylic acid open structure with an alcohol such as methanol or ethanol to form a half ester. In addition, at least one selected from monovalent or divalent metal oxides, hydroxides, organic acid salts, and alkoxides is added to the maleation reaction product in an amount of 10 parts by weight or less, preferably 5 parts by weight or less, and more preferably 0.001 parts by weight or less. If 3 to 3 parts by weight is added to introduce ionic bonds, the adhesive properties at high temperatures are further improved. This ionic bond introduction reaction is carried out by adding a predetermined amount of the solution of the above metal compound to a solution of the reaction product obtained by maleating the block copolymer, by mixing the metal compound in a molten state after re-precipitating and drying the maleate; Alternatively, a method can be used in which a metal compound is added to the maleated copolymer dispersed in a non-solvent and reacted. Furthermore, it is also possible to use an anhydride which is opened into a carboxylic acid group or made into a half ester prior to this ionic bond introduction reaction. Examples of metal compounds include hydroxides such as sodium hydroxide, potassium hydroxide, and lithium hydroxide, zinc acetate,
sodium acetate, magnesium acetate, zinc formate,
Organic acid salts such as magnesium formate, oxides such as zinc oxide, and alkoxides such as sodium methoxide and sodium ethoxide are used. The reason why the amount of the metal compound to be added is limited to the above-mentioned range is that if it is more than this, the melt viscosity of the product becomes high, and furthermore, the adhesiveness deteriorates. In the present invention, when the maleation reaction is carried out in a solvent, the modified copolymer solution is poured into a non-solvent and solidified either after the maleation reaction or after the addition of the metal compound in the process of obtaining the final product. A process is necessary. In this case, the reactant solution may be directly poured into a nonsolvent to solidify it, or
Alternatively, the reactant solution may be concentrated by solvent evaporation and then placed in a non-solvent for solidification. In the latter case, it is also possible to solidify the material while maintaining its shape, for example, in the form of a string. In addition, in the present invention, in order to achieve both excellent adhesive strength and moldability at high temperatures, the melt viscosity of the final product is
1.0× under shear stress of 4.0×10 ⁶ dyne/cm ² at 175℃
10 ³ to 1.0×10 ⁵ poise, preferably 2×10 ³ to 8
×10 ⁴ poise, more preferably 2.5 × 10 ³ to 6 ×
10 ⁴ Must be poise. Additionally, additives such as antioxidants and stabilizers may be added to the above-mentioned product as required. Examples are shown below. Note that all "parts" and "%" in the following examples are expressed by weight. Example 1 Styrene-butadiene-styrene block copolymer (hereinafter abbreviated as SBS) “Califlex TR-1102” with a melt viscosity of 2.3×10 ⁴ poise at 175°C and a shear stress of 2.5× ^{10 6} dyne/cm ² (manufactured by Ciel Chemical)
SBS registered trademark; Butadiene/Styrene = 72/
28) 40g, maleic anhydride 2.0g and toluene 1
Kg was put into two separable flasks and dissolved while raising the temperature to 90°C. 0.2 g of benzoyl peroxide was added to this, and the mixture was reacted for 4 hours with stirring. Half of the reaction product solution α was taken out, 130 ml of dimethylformamide in which 100 mg of zinc acetate (2 water) was dissolved was added to the remaining solution, and the mixture was heated at 80°C for 30 minutes.
Stir for hours. This will be referred to as the β solution. The obtained solutions of α and β were each poured into methanol to precipitate, and extracted with methanol at room temperature for 3 hours.
After adding a small amount of phenolic antioxidant, the mixture was decanted and vacuum-dried at 45° C. overnight. The obtained maleated block copolymer, the block copolymer into which ionic bonds were introduced after maleation, and the untreated block copolymer as a control were each heated at 200°C and a pressure of 50 kg/m ² to form an adhesive layer between two polypropylene sheets. Each laminate was produced by press molding. The polypropylene sheet was press-molded from "Sumitomo Noblen W-111" (registered trademark of Sumitomo Chemical Co., Ltd. for polypropylene). This laminate was used as a short fence with a width of 1 cm, and the T-peel strength was measured at a peeling speed of 200 mm/min. The results are shown in Table 1. In addition, this laminate was used as a short fence with a width of 3 cm in an autoclave for 120 min.
After soaking in water at ℃ for 30 minutes, cut into 1cm wide pieces.
The results of measuring the peel strength at °C in the same manner are also shown. In addition, the modified block copolymer obtained by the above reaction was heated at 175°C with a shear stress of 4.0×
The melt viscosities measured with a melt tension tester at 10 ⁶ dyne/cm ² are shown in Table 2.

【table】

[Table] Also, maleated SBS obtained above, SBS reacted with zinc after maleation, and untreated as a control example.
Using SBS as an adhesive layer instead of the polypropylene sheet, vinylidene chloride/vinyl chloride = 80/20
A laminate was molded in the same manner using a press sheet of vinylidene chloride-vinyl chloride copolymer containing 3 parts of plasticizer with a weight ratio of
℃, pressure 50Kg/cm ² ). The T-peel strength of this laminate was measured in the same manner as above, and the results are shown in Table 3.

[Table] Example 2 The SBS used in Example 1 was reacted with 4.5 parts of maleic anhydride in exactly the same manner as in Example 1, and then zinc acetate dihydrate was added to 100 parts of the copolymer in the solution. 130 ml of a dimethylformamide solution containing 0.25 part or 0.125 part was added and reacted at 80°C for 3 hours. The obtained reaction product solution was post-treated and dried in the same manner as in Example 1. 175 of these products
Table 4 shows the melt viscosity at ℃ and shear stress of 4×10 ⁶ dyne/cm ² . A polypropylene laminate was prepared in the same manner as in Example 1 using these modified SBS as an adhesive layer, and the T-peel strength was measured. Table 5 shows the results.

【table】

[Table] Example 3 1 Put 800 ml of purified benzene into a glass autoclave under a high-purity nitrogen atmosphere and raise the temperature to 55°C.
Add 1.5 ml of 15% by weight n-butyllithium solution in n-hexane, add 15 g of styrene, and
Polymerized for hours. Add 62g of butadiene to this and add 4
Polymerized for hours. Furthermore, 15 g of styrene was added to this and polymerized for 4 hours. The obtained SBS block copolymer liquid was poured into methanol, a small amount of phenolic antioxidant was added, and then dried. The melt viscosity of this SBS is 5.5× at 175℃ and a shear stress of 2.5×10 ⁶ dyne/cm ²
10 ³ It was poise. 20g of this SBS and 1.0g (5 parts) of maleic anhydride
was dissolved in 500 g of toluene, and after raising the temperature to 90°C, 0.1 g (0.5 parts) of benzoyl peroxide was added and reacted for 4 hours. Half of this solution α was taken out, and a dimethylformamide solution (65 ml) containing 50 mg (0.5 parts) of zinc acetate dihydrate dissolved therein was added to the remaining solution, and the mixture was reacted at 80° C. for 3 hours. Let this solution be β. α and β were post-treated in the same manner as in other Examples to obtain maleated SBS and ionically bonded SBS. These 175℃, shear stress 4.0×10 ⁶ dyne/
The melt viscosity in cm ² is as shown in Table 6. Additionally, as a control example, a laminate of polypropylene sheets was prepared in the same manner as in Example 1 using untreated SBS as an adhesive layer. Table 7 shows the temperature dependence of the T-peel strength of these laminates.

【table】

[Table] Example 4 20 g of SBS used in Example 1 and 2 g of citraconic anhydride (methyl maleic anhydride) were dissolved in 500 g of toluene, and after heating to 90°C, benzoyl peroxide was dissolved.
0.2g was added and reacted for 4 hours. Further, 130 ml of a dimethylformamide solution containing 100 mg of zinc acetate (dihydrate) was added to this solution, and the mixture was stirred at 80°C for 3 hours. Post-treatment and drying were carried out in the same manner as in Example 1. The melt viscosity of this material at 175℃ and 4.0×10 ⁶ dyne/cm ² is
It was 3.1×10 ⁴ poise. Further, in the same manner as in Example 1, a polypropylene laminate was prepared using this modified SBS as an adhesive layer, and the T-peel strength was measured while changing the measurement temperature. Table 8 shows the results.

[Table] As explained above, according to the production method of the present invention, since the reaction with the anhydrous maleic compound is carried out in a solvent, it has the characteristic that it does not deteriorate. In addition, unreacted maleic anhydride compounds can be extracted and removed in the step of coagulating the product in a non-solvent, which has the effect of allowing safe use even in applications where hygiene is a problem. Furthermore, in the present invention, a block copolymer having a relatively low molecular weight is used. As a result, it has been found that it not only has excellent moldability, but also has excellent adhesion at high temperatures and water and oil resistance that would be difficult to predict based on conventional wisdom. In addition to the above-mentioned characteristics, the adhesive resin of the present invention also retains the characteristics possessed by the block copolymer composed of conjugated diene and aromatic vinyl. Therefore, it is expected to be used in a wide variety of fields, including adhesion of packaging containers for foods, pharmaceuticals, etc., films, etc., as well as areas where it has traditionally been considered used, and is particularly suitable for adhesion of plastics. For example, polyolefins, polyvinyl chloride, vinylidene resins, polyamide resins,
It is useful as an adhesive for laminating with polyester resins, polycarbonates, etc. Among these, it is most preferably used as an adhesive for laminated packaging materials that can be sterilized by high-temperature retort, taking advantage of the excellent high-temperature adhesive properties and sanitary properties of the present invention.

Claims (1)

[Claims] 1 A represents an aromatic vinyl polymer block, B substantially represents a conjugated diene polymer block, m represents an integer of 1 to 2, n represents an integer of 2 to 8, and X represents n polymer chains. General formula (A-B) _-n A or (A-
B) _o Represented by X, the aromatic vinyl content is 10~
70% by weight, and further at 175℃, 2.5×10 ⁶ dyne/cm ²
Melt viscosity under shear stress of 7.0×10 ² to 6.0
100 parts by weight of a linear or branched block ^copolymer or a mixture thereof having a range of 15
After the maleation reaction with parts by weight, 0 to 10 parts by weight of at least one selected from oxides, hydroxides, organic acid salts, and alkoxides of monovalent or divalent metals is added and reacted, and the metal compound is reacted. Before or after the addition, the modified copolymer solution is poured into a non-solvent and solidified to give a melt viscosity of 1.0×10 ³ to 1.0×10 5 poise under a shear stress of 4.0×10 ⁶ dyne/cm ² at 175 ^° C.
A method for producing a thermoplastic adhesive resin, characterized by obtaining a resin having the following properties.