JPH0522730B2 - - Google Patents

Description

[Detailed description of the invention]

Purpose of the invention Industrial application field The present invention has a rebound resilience of 0 to 30% over a wide temperature range.
The present invention also relates to a low-rebound elastic rubber and a low-rebound elastic rubber foam that has significantly improved workability during the manufacturing process. Recently, there has been a demand for materials with excellent shock absorption performance, especially in athletic equipment. These materials are used for the purpose of absorbing or mitigating excessive impact forces generated during exercise that have a negative impact on the human body. One example of this is the insoles of Sports Shoes, which protect the user from damage to the joints and nervous system of the heel and knee caused by shocks of 2 to 7 times the body weight being applied to the feet while running. I'm protecting you from Conventional technology Conventionally, impact-absorbing materials using polynorbornene (Japanese Patent Application Laid-Open No. 1974-74801), ethylene-
Those using vinyl acetate copolymer (Japanese Patent Application Laid-open No. 53-32441),
Those using urethane elastomer (Japanese Unexamined Patent Publication No. 1983-
54000), one using butadiene resin, and one using butyl rubber, etc., but all of them had inadequate impact resilience and insufficient tensile strength. In view of the above circumstances, the inventors first decided to
We have discovered and proposed a rubber composition that exhibits low impact resilience of 30% or less in a wide temperature range of °C. (Japanese Unexamined Patent Publication No. 179246, Patent Application No. 189379, Patent Application No. 1987-
189380) In addition, the present inventors have continued to study intensively from the viewpoint of "weight reduction", and have found conditions under which weight reduction can be achieved by foaming using a decomposable foaming agent without impairing low rebound resilience, that is, impact absorption performance. have already been proposed. (Special application 1982-205551, Patent application 1983
-71231) By the way, all of the low-resilience vulcanized rubber compositions and vulcanized rubber foams with extremely excellent shock absorption performance that the inventors of the present invention have proposed include styrene-butadiene copolymers with a high styrene content. This styrene-butadiene copolymer with a high styrene content has the property of rapidly decreasing its viscosity at temperatures exceeding 80°C, and this property is important when using this polymer. This is a serious problem, especially in terms of workability. For example, in rubber mixers such as Banbury, the viscosity between the surface and the inside of the polymer mass changes greatly due to the difference in temperature between the surface and the inside of the polymer mass, which causes the polymer mass to slip on the surface during the mixing process, resulting in poor polymer dispersion. It causes. If this poor dispersion occurs, the physical properties will be significantly impaired, the impact absorption performance will be poor, and the breaking strength will be reduced. This poor dispersion of the polymer during kneading with a rubber mixer can be avoided by pre-mixing only with the polymer. The reason for this is that the viscosity change due to temperature of the styrene-butadiene copolymer on the high styrene side, which has a particularly severe viscosity change due to temperature, which is the cause of poor polymer dispersion, can be alleviated by using other polymers. However, premixing only the polymer during the mixing process using the rubber mixer leads to an increase in cost in terms of number of units and power, and is extremely disadvantageous from an industrial standpoint. Problems to be Solved by the Invention An object of the present invention is to provide a low-resilience rubber and a low-resilience rubber foam that are easier to manufacture and have superior physical properties as compared to the above-mentioned conventional techniques. Means for Solving the Constituent Problems of the Invention The present invention will be described in detail below. The first invention is that the content of a-bonded styrene is 45 to 75% by weight during the polymerization process.
Select two or more high styrene content styrene-butadiene copolymers whose combined styrene contents are separated by at least 8% from each other, mix them in a latex state, and then dry them. A mixture of high styrene-content styrene-butadiene copolymers with a total styrene content adjusted between 48% and 68% by weight, a general-purpose rubber with a content of 10% to 40% by weight based on the total amount of mixed rubber, High styrene content styrene consisting of and
A mixed rubber of a butadiene copolymer and a general-purpose rubber, consisting of (a) a filler of 10 to 250 parts by weight per 100 parts of the mixed rubber, and (c) a plasticizer of 0 to 60 parts by weight per 100 parts of the mixed rubber. A vulcanizing agent and a vulcanization accelerator are added to the mixture, and the resulting mixture is heated and cured to produce a low-resilience rubber having an impact resilience of 0 to 30%. In addition, the second invention is such that the rebound resilience obtained by adding a vulcanizing agent, a vulcanization accelerator, and a decomposable foaming agent to the mixture consisting of the three components A, B, and C above and then heating and foaming the mixture is 0 to 30%. It is a low-resilience rubber foam. Of the above component A (mixed rubber), the high styrene content styrene-butadiene copolymer used in the high styrene content styrene-butadiene copolymer mixture is preferably 45 to 75% by weight during the polymerization process, as described above. is 45-65% by weight, more preferably
It is necessary to adjust the content to 45 to 60% by weight, and the bound styrene content of the high styrene content styrene-butadiene copolymer should be selected from two or more materials whose bound styrene content is separated from each other by at least 8% or more, preferably by 10% or more. , they are mixed in the latex state and then used in the dry state. The total styrene content of the mixture of high styrene content styrene-butadiene copolymers obtained by mixing in the latex state is 48 to 68% by weight, preferably 50% by weight.
It needs to be adjusted to ~63% by weight, more preferably 51-57% by weight during the blending process. In addition, from the viewpoint of improving shock absorption performance, it is desirable that the high styrene content styrene-butadiene copolymer to be mixed in the latex state has a Mooney viscosity of 5 to 25, preferably 7 to 20. . In addition, from the viewpoint of workability, in order to adjust the total Mooney viscosity of the high styrene content styrene-butadiene copolymer to 40 to 80, at least one type of styrene-butadiene copolymer other than the low Mooney viscosity and high styrene content styrene-butadiene copolymer mentioned above was selected. The high styrene content styrene-butadiene copolymer has a Mooney viscosity of at least 60, preferably at least 75, more preferably at least 75.
Desirably 90 or higher. Examples of general-purpose rubbers in component (a) above (mixed rubber) include natural rubber, isoprene rubber, butadiene rubber, styrene-butadiene rubber, chloroprene rubber, acrylonitrile-butadiene rubber, and ethylene-propylene rubber, which have a glass transition point of -
A rubber selected from rubbers having a temperature of 20°C or less is preferably used. This general purpose rubber is rated at 40% for all mixed rubbers.
It is mixed in an amount of not more than 10% by weight, preferably 10 to 20% by weight. As mentioned above, the component A (filler) needs to be blended in an amount of 10 to 250 parts by weight based on 100 parts by weight of the mixed rubber, but it is particularly preferably 20 to 100 parts by weight. . These components include calcium carbonate, magnesium carbonate, barium carbonate, strontium carbonate, barium sulfate, calcium sulfate, dolomite, kaolin clay, calcined clay, hard clay, sericite, talc, talc, wollastonite, bentonite, and muscovite. , phlogopite, biotite, aluminum hydroxide, zinc white, activated clay, hallosite, titanium oxide, gypsum, light ash, heavy ash, diatomaceous earth, shirasu, shirasu balloon, and other non-reinforcing or weakly reinforcing fillers. Those selected from the following are preferably used. As mentioned above, the component C (plasticizer) needs to be blended in an amount of 0 to 60 parts by weight based on 100 parts by weight of the rubber, and particularly preferably 10 to 35 parts by weight. This component includes aromatic oils, naphthenic oils, polybutene, organic acid derivatives such as dioctyl phthalate, phosphoric acid derivatives such as tricresyl phosphate, and inorganic acid derivatives such as sulfuric acid derivatives, as long as they can be used normally in rubber. Can be used. The low-resilience rubber of the present invention is produced by adding a vulcanizing agent and a vulcanization accelerator to a mixture consisting of the three components A to C above, and curing the mixture by heating. It can be obtained by adding a vulcanizing agent, a vulcanization accelerator, and a decomposable foaming agent to a mixture of the components and heating and foaming the mixture. In this case, known vulcanizing agents such as organic peroxides, sulfur, and organic sulfur compounds can be used. Vulcanizing agent is usually added to 100 parts by weight of mixed rubber.
0.5-10 parts by weight are used. Further, as the vulcanization accelerator, known ones such as aldehyde-amines, aldehyde-ammonias, dithiocarbamates, guanidines, thiurams, sulfenamides, thiazoles, and thioureas can be used. The vulcanization accelerator is usually used in an amount of 0.5 to 10 parts by weight per 100 parts by weight of the mixed rubber. Decomposable blowing agents include organic blowing agents such as dinitrosopentamethylenetetramine (DPT), azodicarbonamide (AZC), p-toluenesulfonyl hydrazide (TSH), and 4,4'-oxybisbenzenesulfonyl hydrazide (OBSH). Any agent that can be used for foaming rubber, such as inorganic foaming agents such as sodium hydrogen carbonate and the like, can be used. The amount of the blowing agent is 0.5 to 60 parts by weight, preferably 2 to 30 parts by weight, based on 100 parts by weight of the mixed rubber. Furthermore, the low resilience rubber or foam of the present invention includes:
In addition to the above-mentioned components, optional components such as reinforcing agents such as carbon black and silica, waxes for preventing deterioration, and anti-aging agents can be added. The low-resilience rubber or foam of the present invention can be mixed and heat-cured or heat-foamed by a conventional method. In this case, the curing temperature is preferably 110 to 180°C. If the curing temperature is below 110°C, it will take a long time to cure, and if it is above 180°C, the physical properties will deteriorate. Function The low-repulsion elastic rubber of the present invention and the foam can be prepared by mixing in a latex state after polymerization in advance in the pre-kneading stage in the kneading process of a rubber mixer. In addition, this mixing in the latex state after polymerization can be carried out in the blending process during Mooney viscosity adjustment, which is normally carried out in industrial polymer production, so it can be accomplished without increasing the number of man-hours, and the total production cost can be reduced. This is a significant advantage from this point of view. This mixture of high styrene content styrene-butadiene copolymer mixed in a latex state can significantly improve poor workability such as roll adhesion in roll work due to the same reasons as kneading work in a rubber mixer. Also, for mixing in the latex state, use a rubber mixer.
This enables compatibility in a much more microscopic state than physical mixing using rolls or the like. This means that the physical properties of the mixture mixed in the latex state are superior to those mixed in a rubber mixer or roll. Furthermore, by making compatibility possible in a microscopic state, it is possible to exhibit good compatibility between high styrene-containing styrene-butadiene copolymers that are far apart from each other. Further, the mixing of the styrene-butadiene copolymer with a high styrene content in the latex state of the present invention can extremely lower the Mooney viscosity of the styrene-butadiene to be mixed. Shock absorption performance can be further improved by lowering the Mooney viscosity of the styrene-butadiene mixture. As mentioned above, the low-resilience vulcanized rubber composition and vulcanized rubber foam of the present invention have excellent shock absorbing properties, so they can be used for shoe components such as midsole, insole, midsole, turntable rubber sheet, etc. acoustic parts,
Vibration damping materials, shock absorbing materials, vibration damping materials, vibration isolation materials, sound insulation materials, various grips, face materials for table tennis rackets,
It can be suitably used for baseball gloves, gloves, protectors, helmets, etc. Next, the present invention will be explained in detail with reference to examples. Examples 1 to 3 Raw materials prepared by mixing the polymers shown in Table 1 A, B, and C in the latex state with the composition shown in Table 2 were mixed in a rubber mixer at an internal temperature of 80°C. After mixing, the mixture was formed into a sheet using rolls with a surface temperature of 60°C, filled into a mold of 10 x 10 x 0.1 cm, heated and pressurized at 50 kg/cm ² at 145°C for 25 minutes, and then demolded. Physical properties etc. are shown in Table 3. All have impact resilience of 30% or less over a wide temperature range of -10°C to 45°C, and have good workability.

【table】

【table】

【table】

【table】
All numbers are parts by weight

[Table] Comparative Examples 1 to 3 Raw materials prepared by mixing the polymers shown in Table 1 D, E, and F in the polymer state with the composition shown in Table 4 were mixed at a container temperature of 80°C. After mixing with a rubber mixer at ℃, it is made into a sheet with a roll with a surface temperature of 60℃, and this is filled into a 10 x 10 x 0.1 cm mold.
After heating and pressurizing at 50 kg/cm ² and 145° C. for 25 minutes, the mold was demolded.

【table】

[Table] All numbers are parts by weight.
Physical properties etc. are shown in Table 5.

[Table] Example 4 (Example of foam) The raw materials prepared by mixing the polymers shown in Table 1 A in the latex state with the composition shown in Table 2 were mixed at a container temperature of 80°C. After mixing with a rubber mixer, the professional chemicals and foaming material are mixed with a roll with a surface temperature of 60°C and made into a sheet, which is then rolled into a 10×10×1 sheet.
The mixture was filled into a cm mold, heated at 90 kg/cm ² at 140° C. for 30 minutes, and then demolded. Physical properties etc. are shown in Table 3. This also has a rebound resilience of 30% or less over a wide temperature range of -10°C to 45°C, and has good workability. Effects of the Invention A low-resilience rubber and a low-resilience rubber foam can be obtained that have an impact resilience of 0 to 30% over a wide temperature range and have significantly improved workability during the manufacturing process.

Claims (1)

[Claims] 1. A. The bound styrene content is 45 to 75 during the polymerization process.
High styrene content styrene-butadiene copolymers adjusted to % by weight are obtained by selecting two or more types of styrene-butadiene copolymers whose combined styrene content is at least 8% apart from each other, mixing them in a latex state, and then drying them. Total styrene content ranges from 48% to 68% by weight
High styrene content styrene prepared between -
A mixture of a butadiene copolymer, a general-purpose rubber of not more than 40% by weight based on the total amount of mixed rubber, and a mixed rubber of a styrene-butadiene copolymer with a high styrene content and a general-purpose rubber, (a) 100% by weight of the above mixed rubber A vulcanizing agent and a vulcanization accelerator are added to a mixture consisting of 10 to 250 parts by weight of a filler per 100 parts of the mixed rubber, c) a plasticizer of 0 to 60 parts by weight per 100 parts by weight of the above mixed rubber, and the mixture is heated and cured. Low-rebound elastic rubber with an impact elasticity of 0 to 30%. 2. The low resilience rubber according to claim 1, wherein one of the high styrene content styrene-butadiene copolymers to be mixed in the latex state has a Mooney viscosity of 5 to 25. 3 Claims in which at least one copolymer other than the copolymer described in claim 2 among the high styrene content styrene-butadiene copolymers to be mixed in a latex state has a Mooney viscosity of 60 or more. The low-repulsion elastic rubber according to item 1. 4 A. The bound styrene content increases from 45 to 75 during the polymerization process.
High styrene content styrene-butadiene copolymers adjusted to % by weight are obtained by selecting two or more types of styrene-butadiene copolymers whose combined styrene content is at least 8% apart from each other, mixing them in a latex state, and then drying them. Total styrene content ranges from 48% to 68% by weight
High styrene content styrene prepared between -
A mixture of a butadiene copolymer, a general-purpose rubber of not more than 40% by weight based on the total amount of mixed rubber, and a mixed rubber of a styrene-butadiene copolymer with a high styrene content and a general-purpose rubber, (a) 100% by weight of the above mixed rubber a vulcanizing agent, a vulcanization accelerator, and a decomposable blowing agent to a mixture consisting of 10 to 250 parts by weight of a filler per 100 parts by weight of the above mixed rubber; A low-resilience rubber foam with an impact resilience of 0 to 30% obtained by heating and foaming after adding the foam. 5. The low resilience rubber foam according to claim 4, wherein one of the high styrene content styrene-butadiene copolymers to be mixed in the latex state has a Mooney viscosity of 5 to 25. 6 Claims in which at least one copolymer other than the copolymer described in Claim 5 among the high styrene content styrene-butadiene copolymers to be mixed in a latex state has a Mooney viscosity of 60 or more. 4. The low-resilience rubber foam according to item 4.