JPS6257664B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention provides a heat-resistant, oil-resistant material containing a mixture of a thermoplastic block elastic body, a graft copolymer obtained by copolymerizing a diene rubber-like polymer, an aromatic vinyl compound, and an acrylic monomer. The present invention relates to a thermoplastic elastomer composition having excellent properties such as hardness and abrasion resistance. Conventionally, thermoplastic block elastic bodies (hereinafter referred to as block elastic bodies) made of conjugated dienes and aromatic vinyl compounds have shown good rubber elasticity at room temperature.
Melts and flows at high temperatures. This block elastic body is
Generally, it has the property that it can be molded in the same way as thermoplastic resin, and is used for shoe soles and industrial products. However, such block elastic bodies are significantly inferior in heat resistance, oil resistance, and abrasion resistance compared to vulcanized rubber, and in particular, in terms of oil resistance, they are completely dissolved in, for example, kerosene. Therefore, in fields that require oil resistance, although it has advantages in terms of molding process, it has the disadvantage that its applications are extremely limited. Various attempts have been proposed to improve these drawbacks. That is, (1) the block elastic body is crosslinked using peroxide or the like. (2) Mix thermoplastic resin such as olefin. However, no method has been found that practically improves physical properties such as heat resistance, oil resistance, and abrasion resistance in a well-balanced manner. In order to solve the above-mentioned drawbacks, the present invention has been made through intensive research and has resulted in the completion of a composition that has excellent heat resistance, oil resistance, abrasion resistance, etc., and is suitable for rubber shoes, industrial products, etc. . That is, the present invention provides a thermoplastic block elastic body comprising a conjugated diene and an aromatic vinyl compound;
The main component is a mixture of a diene rubber-like polymer, an aromatic vinyl compound and an acrylic monomer, and a graft copolymer obtained by copolymerizing the polymer.
Furthermore, it is characterized in that a naphthenic process oil, an inorganic filler, and a peroxide can also be added. The present invention will be explained in detail below. The block elastic body of a conjugated diene and an aromatic vinyl compound used in the present invention is A(-B-A) _o-1 , (A
-B) _o , (A-B) _oX .
(A in the formula is an aromatic vinyl compound block, B
represents a conjugated diene block, X represents a polyfunctional compound in which n polymer chains are bonded, and n is 2
It is an integer of ~4. ) Conjugated dienes in the block elastic body include 1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene, isoprene, etc., and aromatic vinyl compounds include styrene, α-methylstyrene, vinyltoluene, t -butylstyrene, etc. The block elastomer in the thermoplastic elastomer composition of the present invention may be one in the rubber range, and in particular, the aromatic vinyl compound may be in the range of 25 to 50%.
Preferably, the content is % by weight. If the weight of the aromatic vinyl compound is less than 25%, the block chains of the aromatic vinyl compound that serve as pseudo-crosslinking points will be small and the tensile strength will decrease, making it unusable for practical use. Moreover, if it exceeds 50% by weight, the rubber elasticity will be significantly reduced, which is undesirable. The graft copolymer used in the present invention is composed of a diene rubber polymer, an aromatic vinyl compound, and an acrylic monomer. Examples of the diene rubber polymer include butadiene, isoprene, dimethylbutadiene, cyclopentadiene, Homopolymers of conjugated diene monomers such as chloroprene and cyanoprene, or monomers copolymerizable with these diene monomers, such as styrene, acrylonitrile, methyl methacrylate, ethyl acrylate, isobutylene, 1-butene, etc. Alternatively, a copolymer with two or more types of monomers may be mentioned. Next, the aromatic vinyl compound to be graft copolymerized includes styrene, α-methylstyrene, vinyltoluene, chlorostyrene, t-butylstyrene, and the like. Similarly, the acrylic monomer to be graft copolymerized is one or more of acrylonitrile, methacrylonitrile, methyl acrylate, methyl methacrylate, ethyl acrylate, butyl acrylate, and the like. The proportion of diene rubber polymer in the graft copolymer is 30 to 70% by weight, and the total amount of acrylic monomer and aromatic vinyl compound monomer is 70 to 70% by weight.
It is 30% by weight. Furthermore, the weight percent ratio of acrylic monomer and aromatic vinyl compound is from 40:60 to
It's 10:90. The ratio of diene rubber polymer is 30
If it is less than 70% by weight, the rubbery properties will deteriorate, and if it exceeds 70% by weight, fluidity will decrease and moldability will be poor. In addition, if the acrylic monomer exceeds 40% by weight in the weight ratio of the two monomer components, the grafted material will turn brown, which is undesirable.
If the amount is less than % by weight, the improvement in oil resistance will be insufficient. The composition ratio of the block elastic body and the graft copolymer is 80:20 to 20:80, preferably 75:25 to 25:
It is 75 parts by weight. If there is a large amount of block copolymer outside this range, oil resistance, heat resistance, and abrasion resistance will not be sufficiently improved, and if there is a large amount of graft copolymer, moldability will be poor and rubber elasticity will be poor. Undesirable. The present invention is mainly composed of a mixture of a block elastic material and a graft copolymer, but the effect can be improved depending on the use by using the following additives. That is, the naphthenic process oil is generally commercially available, and preferably,
Compositionally 3-10% aromatic, 20-42 naphthenes
% by weight and 32-65% by weight aliphatic. The amount added is based on 100 parts by weight of components (a) and (b).
The amount is 10 to 80 parts by weight, preferably 20 to 60 parts by weight. If the amount added is less than 10 parts by weight, fluidity will be insufficient,
If it exceeds 80 parts by weight, the improvement in oil resistance will be insufficient. This naphthenic process oil leads to hardness adjustment, fluidity improvement, and cost reduction of the composition. For example, the hardness of general shoe soles is required to have Shore hardness A of 50 to 80, and the addition of the above-mentioned range The required hardness can be achieved by limiting the amount. In addition, as the inorganic filler used in the present invention,
Examples include light or heavy calcium carbonate, magnesium carbonate, barium carbonate, silica, aluminum hydroxide, kaolin clay, and carbon black. The amount added is 10 to 60 parts by weight, preferably 10 to 50 parts by weight, per 100 parts by weight of components (a) and (b). If the amount added is less than 10 parts by weight, it is not substantially useful for improving oil absorption and rigidity, and if it exceeds 60 parts by weight, the impact resilience of rubbery properties is undesirably reduced. Furthermore, in the present invention, the performance can be further improved by crosslinking the composition with a peroxide. That is, the addition of peroxide
It is presumed that co-crosslinking of both the block elastomer and the graft copolymer components progresses and the molecular weight is appropriately increased to such an extent that injection moldability is not inhibited, thereby further improving oil resistance. Types of peroxides include benzoyl peroxide, dikymyl peroxide, ditertiary butyl peroxide, t-butyl peroxybenzoate, t-butyl peroxy acetate, t-butyl peroxy octoate, etc. Particularly preferred is benzoyl peroxide. The amount added is 50 to 2000 PPM, preferably 200 to 2000 PPM, per 100 parts by weight of components (a) and (b).
It is 2000PPM. If it is less than 50PPM, the crosslinking effect will be small and the performance will not improve.
If it exceeds, crosslinking becomes excessive, fluidity decreases, and processability deteriorates. This peroxide is preferably added during the molding step and heated and crosslinked. Furthermore, anti-aging agents, ultraviolet absorbers, antistatic agents, flame retardants, reinforcing agents, foaming agents, colorants, lubricants, fragrances, and other fillers may be added to the composition as necessary. can. The molding method of the present invention can be any molding method such as extrusion molding, injection molding, compression molding, hollow blow molding, etc. depending on the purpose. Applications include various shoe soles and industrial rubber products. The present invention will be explained in detail below with reference to Examples. Examples 1 to 3 First, a block elastic body of component (A) and a graft copolymer of component (B) were obtained by the following manufacturing method. (A) Component production method: Pour 50 dehydrated cyclohexane and 1.5 kg of styrene monomer into a 100 autoclave, and add 150 mmol of n-butyllithium at 40℃.
After addition and polymerization, 7 kg of butadiene was added and polymerized at 60°C for 1 hour. Subsequently, 1.5 kg of styrene monomer was added and polymerized at 40°C for 1 hour. After that, 10 g of methanol was added to terminate the polymerization, and then 4-methyl-2,6-dita-diabutylphenol and trinonyl phosphorite were added as anti-aging agents.
The polymer was added at a rate of 0.5 PHR and precipitated using a steam stripping method. The melt flow index (200
℃, 5Kg load) was 9.6g/10 minutes. (B) Manufacturing method of ingredients: Charge 67 parts of polybutadiene latex (solid content 30%, volume average particle diameter 0.45μ) into an autoclave, then add 186 parts of pure water, 3 parts of sodium dodecylbenzenesulfonate, and 0.002 parts of ferrous sulfate.
Part, ethylenediaminetetraacetic acid tetrasodium
0.004 parts, sodium aldehyde sulfoxylate 0.12 parts, acrylonitrile 4.8 parts, styrene 11.2 parts, t-dodecyl mercaptan 0.096 parts
1 part and 0.03 part of benzoyl peroxide were added, and the mixture was stirred under a nitrogen atmosphere. After heating the contents to 50℃,
Holds time. Then acrylonitrile 19.2
A monomer mixture consisting of 44.8 parts of styrene, 0.384 parts of t-dodecylmercaptan, and 0.12 parts of benzoyl peroxide was continuously added over 8 hours. After the addition was completed, the mixture was further stirred at 70° C. for 2 hours to complete polymerization, thereby obtaining a latex of the graft material. A powdery polymer was obtained by adding an aqueous calcium chloride solution to this and performing a salting out method. Evaluation of the composition Component (A) and component (B) were blended in the composition ratio shown in Table 1 using a Henschel mixer at 40 m/m.
It was extruded into pellets using an extruder. A test piece was made from this pellet by injection molding, and various physical properties were measured. The results are shown in Table 1. In Examples 1 to 3, compared to Comparative Example 1, JIS-
The swelling rate when immersed in No. 1 oil or kerosene is small, that is, the oil resistance is greatly improved, and the temperature dependence of hardness is small, that is, the heat resistance is good. It can be said that it has the characteristic of having a small amount of wear. Comparative Example 1 Table 1 shows the physical properties of only component (A) of the block elastic body. Comparative Example 2 Molding using only component (B) of the graft copolymer:
It was impossible to mold due to poor fluidity.

[Table] Examples 4 to 6 In the method for producing the block elastic bodies used in Examples 1 to 3, the initiator n-
Polymers obtained in the same manner as in Examples 1 to 3 were used, except that 100 mmol of butyllithium was used. The melt flow index (200°C, 5 kg load) of this polymer was 0.01 g/10 minutes. Further, as the graft copolymer, the polymers described in Examples 1 to 3 were used as they were.
In addition, block copolymers, graft copolymers, naphthenic process oils (manufactured by Idemitsu Kosan Co., Ltd., trade names)
NS-100) and as an inorganic filler, heavy calcium carbonate (manufactured by Shiraishi Calcium Co., Ltd., trade name Whiten)
SB) was mixed to a predetermined composition shown in Table 2, and the physical properties were measured in the same manner as in Examples 1 to 3. The results are shown in Table 2.

【table】

[Table] Comparative Example 3 Table 2 shows the physical property values when only the block elastic body was used as the polymer component in Example 4. Comparative Example 4 Table 2 shows the physical property values when only the graft copolymer was used as the polymer component in Example 4. Oil resistance is relatively good, but moldability is poor due to low fluidity, and rubber properties are poor. Examples 7 to 9 In each of the compositions of Examples 4 to 6, a predetermined amount of benzoyl peroxide was further added, and the extruded pellets were evaluated for physical properties in the same manner as Examples 1 to 3. The results are shown in Table 3. show.

[Table] Comparative Example 5 Table 3 shows the physical property values when only the block copolymer was used as the polymer component in Example 8. The above physical property measurement method was based on the following criteria. 1 Shore hardness: JIS-K-6301 (Shore hardness A) 2 Melt flow index: ASTM-D-
Measured at 200℃ and 5Kg load according to 1328. 3 Oil resistance: JIS-K-6301 After immersion in JIS-1 oil and kerosene at 20°C for 20 hours, the weight increase rate was determined. 4 Pico wear: Pico wear amount was determined in accordance with ASTM-D-2228. 5 Repulsion elasticity modulus: Compliant with BS standard No. 903, measurement temperature
20℃.

Claims (1)

[Scope of Claims] 1 (a) 80 to 20 parts by weight of a thermoplastic block elastic body comprising a conjugated diene and an aromatic vinyl compound (b) A diene rubber-like polymer, an aromatic vinyl compound, and an acrylic monomer A thermoplastic elastomer composition comprising as a main component a mixture of 20 to 80 parts by weight of a graft copolymer obtained by copolymerizing the above. 2 (a) 80 to 20 parts by weight of a thermoplastic block elastomer made of a conjugated diene and an aromatic vinyl compound (b) Copolymerization of a diene rubber-like polymer, an aromatic vinyl compound, and an acrylic monomer 20 to 80 parts by weight of a graft copolymer (c) 10 to 80 parts by weight of a naphthenic process oil (d) 10 to 60 parts by weight of an inorganic filler. 3 (a) 80 to 20 parts by weight of a thermoplastic block elastomer made of a conjugated diene and an aromatic vinyl compound (b) Copolymerization of a diene rubber-like polymer, an aromatic vinyl compound, and an acrylic monomer 20 to 80 parts by weight of graft copolymer (c) 10 to 80 parts by weight of naphthenic process oil (d) 10 to 60 parts by weight of inorganic filler (e) Based on 100 parts by weight of components (a) and (b) A thermoplastic elastomer composition containing as a main component a mixture with 50 to 2000 PPM of an organic peroxide.