JP2006213787A - Rubber composition using reclaimed rubber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubber composition containing butyl-based reclaimed rubber, environmentally safe, having sufficient curing rate and giving vulcanized rubber having increased physical properties such as tensile strength. <P>SOLUTION: The rubber composition is obtained by compounding 1-30 wt.% alkylphenol resin based on the weight of rubber component of the butyl-based reclaimed rubber, and a thiazole-based vulcanization accelerator and/or sulfenamide-based vulcanization accelerator in a system obtained by compounding 5-50 pts.wt. butyl-based reclaimed rubber based on the weight corresponding to the rubber component of the butyl-based reclaimed rubber to 50-95 pts.wt. one or more rubber selected from a group consisting of butyl rubber, brominated butyl rubber and chlorinated butyl rubber. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a rubber composition using a butyl-based recycled rubber. More specifically, the present invention provides an environmentally safe and sufficient vulcanization rate by including an alkylphenol resin and a thiazole vulcanization accelerator and / or a sulfenamide vulcanization accelerator as a vulcanization accelerator. The present invention relates to a rubber composition containing a butyl-based reclaimed rubber, which provides a vulcanized rubber having improved physical properties such as tensile strength.

  Today, from the viewpoint of environmental problems and resource saving, there is a strong demand for recycling (recycled rubber) of vulcanized rubber waste such as tires. As a method for regenerating such a vulcanized rubber, for example, a method of applying heat and shear force to the vulcanized rubber using a twin screw extruder (Patent Document 1), or a twin screw extruder is used. A method for producing recycled desulfurized rubber that can be used alone as a rubber raw material for a recycled rubber molded product having practical rubber properties has been proposed (Patent Document 2). These methods of reclaiming vulcanized rubber using a twin screw extruder can selectively cut sulfur crosslinks without breaking the main chain of rubber molecules, so the reclaimed rubber is vulcanized and molded again. The rubber product obtained in this way does not show a significant decrease in rubber properties as in those obtained by conventional methods such as the oil pan method. In recent years, research on reclaiming waste vulcanized rubber using a twin-screw extruder has been underway since the deterioration of rubber properties can be minimized.

  However, the reclaimed rubber generally has a drawback that the vulcanization speed is low and the vulcanization time is too long to be actually used as a raw material for rubber products. In particular, in the case of butyl-based recycled rubber, the main chain has fewer double bonds than ordinary diene-based polymers, and the vulcanization speed is further reduced by lowering the molecular weight by regeneration. In many cases, a thiuram vulcanization accelerator was used. However, thiuram vulcanization accelerators have environmental safety problems associated with nitrosamines generated from them, and their use is not preferred. On the other hand, for the purpose of improving environmental safety and vulcanization speed, it has been proposed to add a benzothiazole vulcanization accelerator and a guanidine vulcanization accelerator to the halogenated butyl rubber (Patent Document 3). The resulting rubber composition does not have a sufficient vulcanization rate. Accordingly, there is a demand for a rubber composition containing a butyl-based recycled rubber, which is nitrosamine-free, has a sufficient vulcanization rate, and has improved tensile strength after vulcanization.

Japanese Patent Laid-Open No. 11-236464 JP-A-9-227724 JP-A-6-166679

  The present invention provides a rubber composition containing a butyl-based recycled rubber, which is nitrosamine-free, has a sufficient vulcanization rate, and has improved tensile strength after vulcanization. Objective.

  In the present invention, in a rubber composition containing a butyl regenerated rubber, a thiazole vulcanization accelerator and / or a sulfenamide vulcanization accelerator is used as a vulcanization accelerator instead of a thiuram vulcanization accelerator, When 1 to 30% by weight of alkylphenol resin is used with respect to the weight of the rubber component of the butyl-based recycled rubber, the tensile strength is increased at a sufficient vulcanization speed without causing the above-mentioned problems related to environmental safety. It has been found that a vulcanized rubber product excellent in physical properties such as thickness can be obtained. The rubber composition of the present invention has a practically good vulcanization rate comparable to that of a rubber composition using a thiazole vulcanization accelerator and / or a sulfenamide vulcanization accelerator as a vulcanization accelerator. Further, the rubber composition of the present invention has significantly improved tensile strength, elastic modulus, etc., compared with a rubber composition using a thiazole vulcanization accelerator and / or a sulfenamide vulcanization accelerator as a vulcanization accelerator. A vulcanizate having the mechanical properties of

  According to the present invention, butyl-based recycled rubber is added to 50 to 95 parts by weight of one or more rubbers selected from the group consisting of butyl rubber (IIR), brominated butyl rubber (Br-IIR) and chlorinated butyl rubber (Cl-IIR). 1 to 30% by weight of an alkylphenol resin and a thiazole vulcanization accelerator and / or sulfene based on the weight of the rubber component of the butyl-based recycled rubber in a system containing 5 to 50 parts by weight corresponding to the rubber component A rubber composition comprising an amide vulcanization accelerator is provided.

  The rubber composition of the present invention is a butyl-based rubber composition because the vulcanized product or rubber product obtained after vulcanization exhibits a high tensile strength in spite of the relatively large amount of butyl-based recycled rubber used. It has an excellent advantage that has not been achieved in the past, which makes it possible to increase the amount of recycled rubber recycled.

  In the rubber composition of the present invention, one or more kinds of rubber selected from the group consisting of IIR, Br-IIR and Cl-IIR are used as a new unvulcanized rubber, and butyl-based recycled rubber is blended therein.

  The butyl-based recycled rubber is not particularly limited by the recycling method, and after pulverizing the crosslinked butyl-based rubber to a predetermined particle size with a pulverizer or the like, a regenerant such as pine tar is mixed and packed in a container, and directly A method in which steam is blown to break down the bridge at high temperature and pressure to regenerate desulfurization (bread method), a shear flow field reaction method in which heat and shear force are applied to the crosslinked rubber, and a Banbury mixer with adjustable shear force Recycled rubber regenerated by a regenerating method such as a method of breaking the cross-linking at high pressure (mechanical cutting regenerating method) can be used.

  The compounding amount of the butyl-based recycled rubber can be an arbitrary ratio with respect to one or more kinds of rubbers selected from the group consisting of IIR, Br-IIR and Cl-IIR, but it is desirable to increase the amount of recycling. In consideration of the balance of rubber properties of the resulting vulcanizate, butyl-based recycled rubber is used with respect to 50 to 95 parts by weight of one or more rubbers selected from the group consisting of IIR, Br-IIR and Cl-IIR. The amount corresponding to the rubber component is preferably 5 to 50 parts by weight. Therefore, the blending amount of the butyl-based recycled rubber can be changed according to the amount of the rubber component contained therein.

  One of the characteristics of the rubber composition of the present invention is that an alkylphenol resin and a thiazole vulcanization accelerator and / or a sulfenamide vulcanization accelerator are used in combination as a vulcanization accelerator.

  Examples of the alkylphenol resin used in the present invention include phenols having an alkyl group having 1 to 18 carbon atoms, such as cresol, isopropylphenol, t-butylphenol, amylphenol, t-octylphenol, nonylphenol, dodecylphenol, allylphenol, cyclohexyl. Examples include those obtained from phenol, 4,6-dioctyl resorcin, and the like, and derivatives thereof such as methylolated derivatives and halogenated derivatives. Such alkylphenol resins are commercially available, and, for example, hitanol 2501Y (trade name, manufactured by Hitachi Chemical Co., Ltd.) and tackol 250-I (trade name, manufactured by Taoka Chemical Industries) can be conveniently used.

  The compounding amount of the alkylphenol resin is 1 to 30% by weight based on the weight of the rubber component of the butyl-based recycled rubber. When the blending amount of the alkylphenol resin is less than 1% by weight, a vulcanization rate comparable to that when only a thiazole vulcanization accelerator and / or a sulfenamide vulcanization accelerator is used as the vulcanization accelerator can be achieved. However, when it exceeds 30% by weight, scorch property may be generated, and further, the effect of improving the tensile strength according to the increase in the amount of the alkylphenol resin cannot be obtained. Therefore, it is not preferable. The reason why the tensile strength is not improved when the blending amount of the alkylphenol resin exceeds 30% by weight is that the crosslinked structure does not develop because the ratio of the alkylphenol resin to the rubber component present in the rubber composition is too high. Conceivable.

  The thiazole vulcanization accelerator used in combination with the alkylphenol resin in the rubber composition of the present invention may be any of those conventionally used. For example, 2-mercaptobenzothiazole, dibenzothiazyl disulfide, 2-mercapto Examples include zinc salt of benzothiazole, sodium salt of 2-mercaptobenzothiazole, cyclohexylamine salt of 2-mercaptobenzothiazole, and 2- (4-morpholinodithio) benzothiazole. Such thiazole vulcanization accelerators are commercially available, and for example, Noxeller M1 (trade name, manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.) can be conveniently used.

  The blending amount of the thiazole vulcanization accelerator may be an amount usually used for the butyl recycled rubber, but is preferably 0.1 to 2.0% by weight.

  In the present invention, the sulfenamide vulcanization accelerator used in combination with the alkylphenol resin may be any of those conventionally used. For example, N-cyclohexyl-2-benzothiazolylsulfenamide, N-tert-butyl -2-Benzothiazolylsulfenamide. Such vulcanization accelerators are commercially available, and for example, Noxeller CZ and Noxeller NS (both trade names) manufactured by Ouchi Shinsei Chemical Industry can be conveniently used.

  The compounding amount of the sulfenamide vulcanization accelerator may be an amount usually used for the butyl recycled rubber, but is preferably 0.1 to 3.0% by weight.

  The rubber composition of the present invention can be produced by a general mixing or kneading method and operating conditions using a commonly used mixing or kneading apparatus such as a Banbury mixer or a kneader. The rubber composition of the present invention comprises one or more rubbers selected from the group consisting of the above IIR, Br-IIR and Cl-IIR, a predetermined amount of butyl-based recycled rubber, a predetermined amount of alkylphenol resin, and a predetermined amount. Kneading a thiazole vulcanization accelerator and / or sulfenamide vulcanization accelerator together with other general rubber compounding agents, or preparing a rubber mixture (masterbatch) of specific components in advance It may be produced by mixing or kneading with a given component.

  The rubber composition of the present invention includes, in addition to the above vulcanization accelerator, reinforcing agents such as carbon black and silica, vulcanization or cross-linking agents, various oils, anti-aging agents, stearic acid, fillers, paraffin oil and the like. You may mix | blend various compounding agents and additives, such as a softener and a plasticizer, with the general compounding method in the quantity generally used according to various uses.

  Since the rubber product obtained by vulcanizing the rubber composition of the present invention has high tensile strength, it can be effectively used as various members of tire products, such as inner liners and treads.

  The present invention will be described in more detail with reference to the following examples and comparative examples, but it goes without saying that the technical scope of the present invention is not limited by these examples.

Manufacture of rubber composition The components excluding sulfur and vulcanization accelerator in the rubber compounding system shown in Table 1 below were kneaded for 3 to 5 minutes with a 1.8 L closed mixer and released when the temperature reached 165 ± 5 ° C. Sulfur and a vulcanization accelerator were added to the batch and kneaded with an 8-inch open roll to obtain rubber compositions of Examples and Comparative Examples. A part of the rubber composition of each example and comparative example was subjected to a vulcanization rate test. Subsequently, the rubber composition residue was press vulcanized at 160 ° C. for 20 minutes in a 15 cm × 15 cm × 0.2 cm mold to prepare a rubber sheet, which was subjected to a tensile test.

Test Method (1) Vulcanization Rate: According to JIS K6300, a vulcanization time T90 at 160 ° C. was determined.
(2) Tensile strength: according to JIS K6251, punched into No. 3 dumbbell test piece of rubber sheets prepared as described above, under the conditions of temperature 160 ° C. and a tensile rate of 40 mm / min, a tensile strength (T _B ) (MPa).

  The test results of each example and comparative example are shown in Table 1 below. In addition, since the content of the rubber component in the butyl-based recycled rubber used in each Example and Comparative Example was 55% by weight, the rubber component of the butyl-based recycled rubber was present in 20 parts by weight in the rubber composition. It will be. In the following examples and comparative examples, the ratio of butyl rubber, brominated butyl rubber or chlorinated butyl rubber and butyl-based recycled rubber was adjusted so that the total rubber component amount in the composition was 100 parts by weight, and the rubber composition The thing was manufactured.

  From Table 1, in the rubber composition in which butyl rubber, brominated butyl rubber or chlorinated butyl rubber is blended with butyl recycled rubber, with the thiazole or sulfenamide vulcanization accelerator, the rubber component of the butyl recycled rubber As compared with those using only thiazole or sulfenamide vulcanization accelerator as the vulcanization accelerator, 1 to 30% by weight of alkylphenol resin was added while maintaining a good vulcanization rate. It can be seen that the strength has increased significantly. Incidentally, in Example 1, compared with the comparative example 1, the vulcanization | cure speed | velocity became about 11% faster, and the tensile strength showed the remarkable increase of about 40%. From Table 1, also about Examples 2-4, in these rubber compositions, compared with what used only the thiazole type | system | group or sulfenamide type | system | group vulcanization accelerator as a vulcanization accelerator, vulcanization | curing of the substantially same grade It can be seen that the tensile strength was remarkably improved while maintaining the speed.

Claims (1)

  In a system in which 50 to 95 parts by weight of one or more kinds of rubber selected from the group consisting of butyl rubber, brominated butyl rubber and chlorinated butyl rubber are blended with 5 to 50 parts by weight of an amount corresponding to a rubber component A rubber composition comprising 1 to 30% by weight of an alkylphenol resin and a thiazole vulcanization accelerator and / or a sulfenamide vulcanization accelerator based on the weight of the rubber component of the recycled rubber.