JPS6255541B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel rubber composition for vulcanization, and more particularly, the present invention relates to a novel rubber composition for vulcanization, and more specifically, it is composed of an unvulcanized rubber and a vinyl aromatic compound-conjugated diene compound block copolymer modified with dicarboxylic acids. This invention relates to a novel vulcanizable rubber composition with improved adhesion to metals and the like. Rubber molded products such as tires, belts, gaskets, and hoses use unvulcanized rubber, carbon black, fillers such as inorganic fillers, softeners such as process oil, anti-aging agents, vulcanizing agents, vulcanization accelerators, etc. Add
After mixing in a Banbury mixer etc. to form an unvulcanized rubber composition, it is extruded, calendered, rolled, etc., molded with reinforcing agents such as cord or cloth, and then vulcanized or cured by heating. It is obtained by a basic process of crosslinking.
In these processes, such as rolling, calendering, and gluing, if the green strength of the unvulcanized rubber composition is insufficient, the unvulcanized rubber composition may break or the sheet may break under its own weight. There were problems such as sagging and poor operability during processing. In addition, in many cases, for example in tire applications, vulcanized rubber compositions are reinforced with metal or synthetic fiber cords, such as steel cords, nylon cords, or polyester cords, but the adhesion between these and unvulcanized rubber is insufficient, peeling easily occurs at the interface between the two, and it is difficult to exert a reinforcing effect. For this reason, attempts have been made to subject the steel cords and the like to special surface treatments or to add compounding agents to improve adhesion, but these efforts have not always produced sufficient effects. Furthermore, in applications such as anti-vibration rubber, the adhesion between the rubber composition and metals such as iron is poor, and continuous vibration can cause peeling at the adhesive surface, reducing the anti-vibration effect. The object of the present invention is to improve the green strength of a vulcanized rubber composition and to improve its adhesion to metals or synthetic fibers. (a) Component: Unvulcanized rubber (b) Component: A modified block copolymer in which a molecular unit containing a dicarboxylic acid group or its derivative group is bonded to a vinyl aromatic compound-conjugated diene compound block copolymer. Combined component (c): Vulcanizing agent This is a rubber composition for vulcanization, consisting of the above (a) to (c) and optionally additives such as a filler and a softener. The present invention will be described in detail below. The unvulcanized rubber of component (a) of the present invention is a rubber substance that exhibits so-called rubber elasticity by vulcanization using a vulcanizing agent or crosslinking agent such as sulfur or peroxide. The unvulcanized rubber mentioned above includes natural rubber, polybutadiene rubber, styrene-butadiene rubber, acrylonitrile-butadiene rubber, polyisoprene rubber, butyl rubber, ethylene-propylene rubber, ethylene-propylene-diene rubber, acrylic rubber, polychloroprene rubber, and silicone rubber. , fluorocarbon rubber, epichlorohydrin rubber, etc. Among the above, those containing conjugated diene compounds such as natural rubber, styrene-butadiene rubber, acrylonitrile-butadiene rubber, polyisoprene rubber, butadiene-isoprene rubber, and butyl rubber. is preferred. Examples of polybutadiene rubber include high cis polybutadiene rubber and low cis polybutadiene rubber. The styrene-butadiene rubber has a styrene content of 3 to 50% by weight. Styrene-butadiene random copolymer rubber obtained by emulsion polymerization method or solution polymerization method, polymer block mainly composed of styrene and having a styrene content of 3 to 50% by weight, obtained by solution polymerization method 1
Unvulcanized rubber with comparatively poor green strength, such as styrene-butadiene block copolymer rubber, which has one polymer block mainly composed of 50% and butadiene, and high styrene rubber with a styrene content of more than 50% by weight. Can be mentioned. These are those in which the effects of the present invention can be satisfactorily exhibited. Among the various rubbers mentioned above, polybutadiene rubber,
Styrene-butadiene random copolymer rubber is
The unvulcanized rubber used in the vulcanized rubber composition of the present invention is one that can maximize the effects of the present invention. These rubbers can be used in combination of two or more. Next, the modified block copolymer which is component (b) of the present invention is a block copolymer consisting of a vinyl aromatic compound and a conjugated diene compound as a base, and a molecular unit containing a dicarboxylic acid or its derivative group. are combined. The block copolymer serving as the base is generally obtained by an anionic polymerization method using a lithium compound as a catalyst, and contains one or more, preferably two or more polymer blocks mainly composed of a vinyl aromatic compound and a conjugated diene compound. It contains one or more polymer blocks mainly composed of. The content of vinyl aromatic compounds in this block copolymer is generally 5 to 5.
95% by weight, preferably 10-85% by weight. In addition, in the block copolymer, the ratio of the polymer block mainly consisting of a vinyl aromatic compound to the polymer block mainly consisting of a conjugated diene compound is
Preferably it is in the range of 10/90 to 90/10. In a polymer block mainly composed of a vinyl aromatic compound, the content of the vinyl aromatic compound is 60% by weight or more, preferably 80% by weight or more, particularly preferably 100% by weight, while the content is mainly composed of a conjugated diene compound. In the polymer block, the content of vinyl aromatic compounds is not more than 40% by weight, preferably
It is 30% by weight or less. The distribution of minor components in each polymer block may be random, tapered, partially block-like, or a combination thereof. When there are two or more polymer blocks, they may have the same structure or different structures. Vinyl aromatic compounds constituting the block copolymer include styrene, α-methylstyrene, vinyltoluene, etc., and conjugated diene compounds include butadiene, isoprene, 1,3-pentadiene, etc. In the present invention, a styrene-butadiene block copolymer having a type 4 structure of butadiene-styrene-butadiene-styrene is particularly effective as the base block copolymer. In the block copolymer, the number average molecular weight of each polymer block is 1000 to 300000, preferably 5000.
~100,000, and the number average molecular weight of the entire block copolymer is 10,000 to 500,000, preferably 20,000.
~300000, and the molecular weight distribution ranges from 1.01 to 10. Further, the molecular structure of the block copolymer may be linear, branched, radial obtained by using a polyfunctional coupling agent, or any combination thereof. The conditions for the polymer structure of the block copolymer described above are preferable conditions for the modified block copolymer to achieve the effects of the present invention. It is possible to use not only one type of block copolymer, but also a combination of two or more types having different structures. Next, the modified block copolymer of the present invention is obtained by adding an unsaturated dicarboxylic acid or a derivative thereof to the above block copolymer, and these unsaturated dicarboxylic acids or derivatives thereof are , is added to the conjugated diene moiety of the block copolymer at the active unsaturated bond position. On average, each molecule of the block copolymer has one
In order for the rubber composition for vulcanization to have sufficient adhesion, it is necessary for the rubber composition for vulcanization to have sufficient adhesion. be. Examples of the unsaturated dicarboxylic acids or derivatives thereof include maleic acid, fumaric acid, chloromaleic acid, itaconic acid, cis-4-cyclohexene-
1,2-dicarboxylic acid, endo-cis-bicyclo[2,2,1]-5-heptene-2,3-dicarboxylic acid, acid anhydrides of these dicarboxylic acids,
Examples include esters and amides, with maleic acid, fumaric acid, and maleic anhydride being preferred. The modified block copolymer of the present invention can be obtained by reacting a block copolymer with an unsaturated dicarboxylic acid or a derivative thereof in a molten state or a solution state, with or without using a radical initiator. . The method for producing these modified block copolymers is not particularly limited in the present invention, but the modified block copolymers obtained may contain undesirable components such as gel, or their fluidity may be reduced, resulting in a processing method. Production methods that result in poor quality are undesirable; for example, an anti-gelling agent is present in an extruder, etc., as shown in Japanese Patent Application Laid-open No. 55-38803 (Japanese Patent Application No. 53-99102), so that substantially no radicals are generated. A method in which the addition reaction is carried out under such melt mixing conditions is preferred. In addition, the modified block copolymer contains metal 1,
It is also possible to use those which are ionicly crosslinked with di- or trivalent ions. Next, in the vulcanizing rubber composition of the present invention, although it is possible to mix the (a) component and the (b) component at any desired blending ratio, for 100 parts by weight of the (a) component, Component (b) is generally mixed in an amount of 1 to 200 parts by weight, preferably 5 to 100 parts by weight, and more preferably 5 to 50 parts by weight. In this case, the proportion of dicarboxylic acid groups or derivative groups thereof contained in component (b) is adjusted to be 0.05 to 5% by weight based on the total amount of components (a) and (b). This is preferable in order to exhibit good adhesion to metals or fibers. In addition to sulfur, the vulcanizing agent for component (c) includes peroxide crosslinking agents. The composition of the present invention has component (a), component (b), and component (c) as essential components, but in addition to these, the composition contains additives such as fillers and softeners. It is suitable as a rubber composition for use. Examples of fillers include carbon black, white carbon, calcium carbonate, magnesium carbonate, silica, clay, talc, etc., and softeners include naphthenic process oils or aromatic process oils used as rubber developing oils. etc. are preferable. (c) Ingredients and amounts of fillers and softeners are (a)
To 100 parts by weight of the total amount of component (b), 0.01 to 10 parts by weight of component (c), 1 to 200 parts by weight of filler, and 1 to 200 parts by weight of softener are added. Furthermore, other additives such as a vulcanization accelerator, a lubricant, a coloring agent, and an antioxidant can be added to the composition of the present invention. The vulcanizing rubber composition of the present invention can be used for tires, packing, anti-vibration rubber, rubber hoses, industrial materials, canvas fabrics,
It can be used as a material for various rubber molded products such as electric wires and balls. The composition of the present invention is characterized by improved green strength and improved adhesion to metal materials or synthetic fibers, and since component (b) of the present invention itself is a polymeric substance, it has a low molecular weight. One of its characteristics is that it does not deteriorate the mechanical properties after vulcanization, unlike the compounds described above. Hereinafter, the present invention will be explained in more detail with reference to some examples, but it goes without saying that the scope of the present invention is not limited to these examples. Reference Example 1 [Preparation of modified block copolymer] Using Sample P, which is a thermoplastic elastomer of styrene-butadiene block copolymer, a modified block copolymer (Sample P) to which maleic anhydride was grafted was prepared by the method shown below. ) was obtained. Note that sample p was obtained using n-butyllithium as a polymerization catalyst in a hexane solution,
Based on the polymerization method and analysis results, it is thought to have the following structure. Polymer structure: B ₁ -S ₁ -B ₂ -S ₂ (linear) B ₁ = 18% by weight [B] / [S] = 16/2 (tapered) S ₁ = 17% by weight [B] / [ S] = 0/17 B ₂ = 49% by weight [B] / [S] = 46/3 (tapered) S ₂ = 16% by weight [B] / [S] = 0/16 However, B _o ...butadiene Polymer block mainly composed of S _o ...Polymer block mainly composed of styrene The integer n represents the order along the molecular chain. [B]... Butadiene content (% by weight relative to the entire block copolymer) [S]... Styrene content (% by weight relative to the entire block copolymer) The same descriptions will be used in the following examples. Styrene content: 38% by weight Block styrene content: 33% by weight Weight average molecular weight (Mw): 81000 Number average molecular weight (Mn): 62000 Melt index: 11.0g/10mm (JIS-K-6870, load 5Kg, 200℃) 1.5 parts by weight of maleic anhydride and 0.3 parts by weight of BHT as anti-gelling agent for 100 parts by weight of sample p.
(butyl hydroxytoluene) and 0.2 parts by weight of phenothiazine were added, and these were mixed uniformly using a mixer. This mixture was supplied to a 40 mm extruder (single screw, full-flight screw, L/D=24) under a nitrogen atmosphere, and a modification reaction was carried out at a cylinder temperature of 190 to 210°C. The obtained polymer was dried under reduced pressure to remove unreacted maleic anhydride. The analysis results of the modified block copolymer (sample P) show that the melt index is 7.3g/10mm and the toluene insoluble content is 7.3g/10mm.
The amount of maleic anhydride added was 0.70 parts by weight per 100 parts by weight of the block copolymer, as determined by titration with sodium methylate. Reference example 2 [Preparation of modified block copolymer] Styrene content is 70% by weight, number average molecular weight is
Using a 21000 styrene-butadiene type 2 block copolymer (sample q), 5 parts by weight of maleic anhydride and 0.5 parts by weight of phenothiazine as a gelling inhibitor were added to 100 parts by weight of the block copolymer, and the mixture was processed in a processing kneader. By kneading in a nitrogen atmosphere, a modified block copolymer (sample Q) having an added amount of maleic anhydride of 4.2 parts by weight was obtained. Examples 1 to 4, Comparative Examples 1 to 2 As the unvulcanized rubber of component (a), BR (manufactured by Asahi Kasei Kogyo, polybutadiene rubber, trade name diene
NF35R, Mooney viscosity 35), SBR-1 (manufactured by Asahi Kasei Corporation, styrene-butadiene rubber, trade name Tuffden 2000R, Mooney viscosity 45, styrene content 25)
%), SBR-2 (Nippon Elastomer Co., Ltd., styrene-butadiene block copolymer rubber, Solprene
1205, Mooney viscosity 47, styrene content 25%), modified block copolymer samples P and sample Q were used as component (b), and unmodified block copolymer samples p and q were used for comparison. Further, additives were added in the formulation shown below to prepare a rubber composition for vulcanization. Regarding these compositions, we measured green strength and elongation in the unvulcanized state, adhesive peel strength with a steel plate (surface polished) in the vulcanized state, and adhesive strength with steel cord and nylon cord using the H test method. Ta. The results are shown in Table 1. Total of components (a) and (b) (ratio is variable) 100 parts by weight HAF carbon 50 Aroma process oil 10 Zinc white 3 Stearic acid 2 Vulcanization accelerator CZ 1.5 Sulfur 1.75 Vulcanization conditions: 141℃ x 30 minutes

【table】

[Table] As shown in Table 1, the compositions of the present invention of Examples 1 to 4 have superior green strength and elongation values in the unvulcanized state compared to the compositions of Comparative Examples 1 and 2. In addition, it has good adhesion to steel plates, steel cords, and nylon cords after vulcanization. Example 5, Comparative Example 3 Natural rubber (RSS1
Using a soft and hard product (Mooney viscosity 52),
A composition of natural rubber/sample P = 80/20 was prepared, and a vulcanized rubber having the same composition as in Example 1 was prepared using this composition. A comparative example composition was also prepared using only natural rubber. Regarding these compositions, vulcanization conditions (vulcanization conditions)
The adhesive strength between the steel cord and the nylon cord was measured using the H test method at 141°C for 20 minutes.
The results are shown in Table 2.

[Table] As shown in Table 2, the effect of adding Sample P is clear.

Claims (1)

[Claims] 1 Component (a): Unvulcanized rubber (b) Component: A modified vinyl aromatic compound-conjugated diene compound block copolymer with a molecular unit containing a dicarboxylic acid group or its derivative group bonded to it. Block copolymer component (c): A rubber composition for vulcanization consisting of a vulcanizing agent, components (a) to (c), and optionally additives such as a filler and a softener. 2. The composition according to claim 1, wherein the unvulcanized rubber contains a conjugated diene compound. 3. Claim 2 in which the unvulcanized rubber is one or more selected from natural rubber, polybutadiene rubber, styrene-butadiene rubber, acrylonitrile-butadiene rubber, polyisoprene rubber, butadiene-isoprene rubber, and butyl rubber.
Compositions as described in Section. 4. The composition according to claim 3, wherein the unvulcanized rubber is polybutadiene rubber. 5. The composition according to claim 3, wherein the unvulcanized rubber is styrene-butadiene rubber. 6 Styrene-butadiene rubber contains styrene from 3 to
The composition according to claim 5, which is a styrene-butadiene random copolymer rubber containing 50% by weight. 7 Styrene-butadiene rubber contains styrene from 3 to
Claim 5 which is a styrene-butadiene block copolymer rubber containing 50% by weight and containing one polymer block mainly composed of styrene and one polymer block mainly composed of butadiene. Composition of. 8. Claims 1 to 7, wherein the modified block copolymer contains 0.05 to 20 parts by weight of a molecular unit containing a dicarboxylic acid group or a derivative group thereof per 100 parts by weight of the base block copolymer. Compositions as described in Section. 9. The composition according to claims 1 to 8, wherein the dicarboxylic acid derivative group is a dicarboxylic acid anhydride group. 10 The block copolymer of component (b) has two or more polymer blocks mainly composed of vinyl aromatic compounds,
Claim 1, which contains one or more polymer blocks mainly composed of a conjugated diene compound
The composition according to items 1 to 9. 11 The block copolymer of component (b) is B-A-B-
Claim 1 which is the structure of A (A: polymer block mainly composed of a vinyl aromatic compound, B: polymer block mainly composed of a conjugated diene compound)
Composition according to item 0. 12. The composition according to claims 1 to 11, wherein the block copolymer component (b) is a styrene-butadiene block copolymer. 13 For 100 parts by weight of component (a), add 1 to 200 parts of component (b).
The composition according to any one of claims 1 to 12, wherein the composition is blended in parts by weight. 14 Claims in which the molecular unit containing a dicarboxylic acid group or its derivative group contained in component (b) is 0.05 to 5% by weight, based on the entire composition of components (a) and (b). The composition according to item 13. 15. The composition according to claims 1 to 14, comprising 0.01 to 10 parts by weight of component (c) based on 100 parts by weight of the total amount of components (a) and (b). 16 Claims comprising 0.01 to 10 parts by weight of component (c), 1 to 200 parts by weight of filler, and 1 to 200 parts by weight of softener, per 100 parts by weight of the total amount of components (a) and (b). Paragraphs 1 to 15
Compositions as described in Section.