JPH0639507B2 - Room temperature curable elastic composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a room temperature curable elastic composition. More specifically, the present invention relates to a room temperature curable elastic composition obtained by adding and blending an acrylic acid ester, an organic peroxide, and a decomposition accelerator for the organic peroxide to powder rubber that has been developed in recent years.

(Prior Art) Generally, a rubber elastic body made of rubber is used as a vulcanizing agent and a vulcanizer with a conventional kneading machine such as a kneading roll machine, an internal mixer, or a double-arm kneader. An accelerator and other compounding agents for rubber are added and kneaded to form a rubber kneaded product, and then a pressure molding machine such as a roll molding machine, an extrusion molding machine, a compression molding vulcanizer, an injection molding vulcanizer,
Pressure molding with calender rolls, and further vulcanizer, such as vulcanizer, hot air circulation vulcanizer, drum vulcanizer, fluidized bed vulcanizer, compression molding vulcanizer, injection molding vulcanizer The pressure-molded rubber kneaded material is heated and cured at a high temperature of 100 ° C. or higher,
A method of obtaining a rubber elastic body is adopted. That is, the method for obtaining a rubber elastic body that has been conventionally used has an extremely long manufacturing process and is complicated as described above, and a kneader, a pressure molding machine, and a vulcanizer are required, and This is an extremely uneconomical method in terms of manufacturing cost and energy consumption, since it requires energy to heat and cure the rubber kneaded product at a high temperature of 100 ° C. or higher.

On the other hand, a method of curing a pressure-molded rubber kneaded product at room temperature by omitting the step of heating and curing it at a high temperature using a vulcanizer can be considered. As a concrete method, a conventional method is to add and knead a room temperature curing agent to a veil-shaped or chip-shaped rubber with a kneader, then press-mold and then room-temperature cure, but rubber is kneaded during kneading. Since the machine receives high shearing force to generate heat, the added room temperature curing agent causes a reaction and cures during kneading or immediately after taking out the rubber mixture from the kneader. For this reason, the subsequent molding by a pressure molding machine cannot be performed, and this method is not generally adopted. Some room temperature curing agents do not cause a curing reaction even if heat is generated during kneading of rubber. However, when such a curing agent is used, the curing reaction after pressure molding is slow, and it takes several months or more for the pressure-molded kneaded product to cure at room temperature.
This method is also not generally used except in special cases.

For this reason, it has been unavoidable to adopt the conventional uneconomical method described above, and there is a strong demand for a room temperature curable elastic composition capable of omitting a heat curing step under a high temperature by a vulcanizer. Is the reality.

(Problems to be Solved by the Invention) The present invention is a composition that can reduce the manufacturing cost and energy consumption, which are problems in obtaining a rubber elastic body. That is, the present invention provides a room temperature curable elastic composition capable of omitting the step of heating and curing a pressure-molded rubber kneaded product under high temperature using a conventional vulcanizer using powder rubber developed in recent years. Is.

(Means and Actions for Solving Problems) The present invention is made by adding and stirring an acrylic acid ester, an organic peroxide, and a decomposition accelerator for the organic peroxide to powder rubber developed in recent years. A room-temperature-curable elastic composition that exhibits a room-temperature curing reaction only by pressure-molding with a pressure-molding machine and can obtain an elastic body having extremely excellent mechanical properties.

The present invention will be described in detail below.

The present invention resides in a composition obtained by adding and stirring an acrylic acid ester, an organic peroxide, and a decomposition accelerator of the organic peroxide to powder rubber. The addition stirring referred to in the present invention means mixing of an acrylic acid ester, an organic peroxide and a decomposition accelerator of the organic peroxide with powder rubber, and the mixing is carried out by using a commonly used powder mixer. Examples of the powder mixer include a ribbon blender, a high speed mixer, a stirring blade type mixer, a paddle mixer, a muller mixer and a tumble mixer. Alternatively, they can be mixed in a container with a stick, a bamboo spatula, or the like. The mixing temperature is such a temperature that the powdery rubber does not become an agglomerate during mixing, and is usually room temperature. The mixing time is not limited, but it is preferable to mix until the acrylic acid ester, the organic peroxide and the decomposition accelerator of the organic peroxide are sufficiently dispersed in the powder rubber. The obtained room temperature curable elastic composition is molded by the above-mentioned pressure molding machine and then cured at a room temperature for several hours to obtain an elastic body. When the above-mentioned kneading machine is used in place of the powdered rubber which is one component of the composition of the present invention, and when it is intended to obtain a bale-shaped, rubber or chip-shaped rubber, acrylic ester, organic peroxide and organic peroxide are used. It takes a long time to add and knead the decomposition accelerator of the product, and the heat of the rubber causes the rubber to harden during kneading.
The next press molding machine cannot be used. That is, the composition of the present invention can be achieved only by using the recently developed powder rubber.

The powder rubber used in the present invention is not particularly limited, and examples of powder rubber include natural rubber and acrylonitrile-
Examples thereof include powder rubbers such as butadiene copolymer rubber, styrene-butadiene copolymer rubber, polybutadiene rubber, polychloroprene rubber, ethylene propylene copolymer rubber, polyisoprene rubber, chlorosulfonated polyethylene, and polyacrylate rubber. These powdered rubbers can be produced by pulverizing and crushing bale-like or chip-like rubber, spray-drying rubber latex, physical means such as freezing, coagulation, co-precipitation, microcapsule of rubber latex. Method or a chemical method such as a polymer ion complex method. The present invention can be applied to powdered rubber obtained by any of these methods. And these powder rubbers can be used individually or in mixture. An example of the method for producing the powdered rubber is, for example, the method for producing the powdered rubber described in JP-A-53-73244. The production method is to mix an anionic or nonionic rubber latex with an anionic water-soluble polymer, and then to mix the anionic water-soluble polymer with a cationic polymer capable of causing coacervation, a ionic surfactant. There is a powdered rubber obtained by mixing the above components, separating the rubber particles from the rubber latex, adding and mixing the synthetic resin emulsion, dehydrating and drying. The composition of the present invention is applied to powder rubber having a particle diameter of powder rubber of 5 mm or less, preferably 2 mm or less, and more preferably 1 mm or less. If the particle size exceeds 5 mm, the dispersion of acrylic ester, organic peroxide, and decomposition promoter of organic peroxide in the powder rubber becomes insufficient when mixing with a powder mixer, resulting in elasticity with excellent mechanical strength. I can't get a body.

The acrylic acid ester referred to in the present invention refers to an acrylic acid ester and / or a methacrylic acid ester, and when these are mixed and referred to as a (meth) acrylic acid ester, alkyl (meth) acrylate, (meth) acrylic acid Hydroxyalkyl acid, glycidyl (meth) acrylate, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate , Trimethylolpropane tri (meth) acrylate, trimethylolethane tri (meth) acrylate, tetramethylolmethane tetra (meth) acrylate, reaction of methacrylic acid with glycols and polybasic acid The polyester (meth) acrylate thus obtained, the epoxy (meth) acrylate obtained by the reaction of the epoxy compound and (meth) acrylic acid, the polybasic acid and the amino alcohol are reacted, and then the (meth) acrylic acid is reacted. Amide (meta)
Specific examples thereof include urethane (meth) acrylate obtained by reacting an acrylate, a hydroxyalkyl (meth) acrylate and a polyisocyanate compound, tetrahydrofurfuryl (meth) acrylate, and diethylaminoethyl (meth) acrylate. These are used alone or as a mixture. And, 0.1 to 50 parts by weight, preferably 5 to 30 parts by weight, and more preferably 10 to 100 parts by weight of the powdered rubber used of these acrylic acid esters.
20 parts by weight are mixed. When the amount of the acrylic ester is less than 0.1 part by weight, the room temperature curable elastic composition has a low degree of curing, and the elastic body does not exhibit sufficient mechanical strength. Even if it is mixed in an amount of more than 50 parts by weight, the mechanical properties of the obtained elastic body do not change and have no industrial value.

Examples of the organic peroxides used in the present invention include ketone peroxides, diacyl peroxides, dialkyl peroxides, hydroperoxides, and the like, such as methyl ethyl ketone peroxide, methyl isobutyl ketone peroxide, cyclohexanone peroxide, acetyl. Peroxide, lauroyl peroxide, benzoyl peroxide, p-cyclobenzoyl peroxide, 2,4-dichlorobenzoyl peroxide, isobutyl peroxide, t-butyl hydroperoxide, cumene hydroperoxide,
Di-isopropylbenzene peroxide, di-t-butyl peroxide, t-butylcumyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di- (t-butylperoxy) -hexane, etc. Can be mentioned. These may be used alone or in combination. The amount of organic peroxide in the composition is 0.1 to 30 parts by weight per 100 parts by weight of powder rubber used. It is preferably 0.5 to 10 parts by weight, more preferably 1 to 5 parts by weight. If the amount is less than 0.1 part by weight, the amount of the organic peroxide is small, so that the curing reaction of the composition requires a long time and is not industrially valuable. Further, when the amount is more than 30 parts by weight, the composition cures extremely rapidly, the composition cures before molding by pressure molding, and a molded elastic body composition cannot be obtained.

The decomposition promoter of the organic peroxide used in the present invention is a tertiary amine, a metal complex of acetylacetone, a metal salt of naphthenic acid, a thiourea compound, or an amine-aldehyde condensate, for example, N, N- Dimethylaniline, N, N-dimethyl-p-toluidine, acetylacetone vanadyl,
Copper naphthenate, cobalt naphthenate, trimethylthiourea, ethylenethiourea, aldol-α-naphthylamine, triethylenetetramine and the like can be mentioned. And these are used individually or in mixture. The amount of the organic peroxide decomposition accelerator used in the composition of the present invention is 0.01 to 30 parts by weight per 100 parts by weight of the powder rubber used. Preferably 0.1 to 15 parts by weight, more preferably
0.5 to 5 parts by weight is blended. If the amount of the organic peroxide decomposition accelerator is less than 0.01 part by weight, the composition is hard to cure at room temperature and is not practical. Further, even if the amount is more than 20 parts by weight, the effect on the curing rate does not change so much.

In obtaining the composition of the present invention, known additives for rubber, such as an antioxidant, a stabilizer, a vulcanizing agent, a vulcanization accelerator, and carbon black, are used as long as the characteristics of the present invention are not impaired. White fillers, softeners, plasticizers, colorants, flame retardants, etc. are added as needed.

(Effects of the Invention) As is clear from the above description, the room temperature curable elastic composition of the present invention has excellent mechanical properties, and at the same time, is made of conventional veil-shaped or chip-shaped rubber as a raw material, and is elastic It is a composition in which the heating and curing step by a vulcanizer, which is indispensable in the production of a body, can be omitted, and further, the room temperature curing time is remarkably shortened, and has an extremely excellent feature in terms of production cost and energy consumption.

(Examples) The present invention is described below with reference to examples, but the present invention is not limited to these examples. The powdered rubber used in the examples was prepared according to the method for producing powdered rubber in Japanese Patent Application No. 53-73244. All parts are parts by weight.

Examples 1 to 3 and Comparative Example 1 Table 1 shows the particle size produced from polychloroprene rubber (hereinafter abbreviated as PCR) latex (latex of trade name "Skyprene B-30", manufactured by Toyo Soda Kogyo Co., Ltd.). 1 shows a room temperature curable elastic composition produced by using a powder PCR having an average particle size of 1 mm or less and 0.5 mm. The method for obtaining the composition was performed as follows.

In Example 1, the powder PCR was put in a stirring blade type mixer No. 3, and 5 parts of zinc flower were added to 100 parts by weight of the powder PCR used.
Parts by weight, 10 parts by weight of carbon black, and 4 parts by weight of benzoyl peroxide are added, and the temperature is 850 for 15 seconds at room temperature.
The rotating blade was rotated at rpm to uniformly mix, and then the rotating blade was rotated while the powder PCR100 used was adjusted on the one hand.
10 parts by weight of methyl methacrylate, based on parts by weight,
1 part by weight of dimethylaniline and 0.1 part by weight of hydroquinone monomethyl ether were added dropwise over 1 minute while adding a solution of the three components, and the mixture was further stirred for 30 seconds.
A room temperature curable elastic composition was obtained. Next, the obtained composition was formed into a sheet shape for 15 seconds using an 8 ″ roll forming machine manufactured by Toyo Seiki Co., Ltd., and the sheet was put into a sheet-like mold having a thickness of 2 mm, and the pressure was 150 kg / cm ² , In order to know the mechanical properties of the molded product, pressure molding was carried out for 20 minutes at room temperature using a pressure molding machine, and the resulting molded product was left standing at room temperature for 3 hours for curing.
A sample was prepared according to JIS K 6301 and a tensile test was performed.

Example 2 followed the method of Example 1 except that 10 parts by weight of methyl methacrylate of Example 1 was changed to 20 parts by weight. Example 3 is the benzoyl peroxide 4 of Example 1.
The method of Example 1 was followed except that 3 parts by weight of cumene hydroperoxide and 1 part by weight of dimethylaniline were changed to 2 parts by weight of triethylenetetramine. In Comparative Example 1, the powder PCR of Example 1 was changed to a chip-like PCR (trade name “Skyprene B-30” manufactured by Toyo Soda Kogyo Co., Ltd.), and the chip-like PCR was wound around an 8 ″ roll molding machine. An attempt was made to obtain a composition similar to that of No. 1 by roll kneading, but 10 parts by weight of methyl methacrylate, 1 part by weight of dimethylaniline and 0.1 parts of hydroquinone monomethyl ether were used.
The mixture of 3 parts by weight of the solution into the PCR is slow,
It took 40 minutes to knead, and the composition had already been cured, probably because of the heat generation of the rubber during kneading, and could not be molded by the pressure molding machine.

As is apparent from Table 1, it is understood that the molded articles obtained from the compositions of the present invention of Examples 1 to 3 have extremely excellent mechanical properties. It is considered that this is because the acrylic acid ester, the organic peroxide and the decomposition accelerator of the organic peroxide in the composition of the present invention contribute to the curing reaction of the powder PCR.

Examples 4 and 5 and Comparative Example 2 Acrylonitrile-butadiene copolymer rubber (hereinafter referred to as NBR
Table 2 shows the room temperature curable elastic body composition produced by using a rubber powder having a particle size of 1 mm or less and an average particle size of 0.5 mm manufactured from latex (trade name "Nipol1561" manufactured by Nippon Zeon Co., Ltd.). Shown in. The method for obtaining the composition was performed as follows.

In Example 4, the powder NBR was placed in a stirring blade type mixer of 30 and 5 parts of zinc white was added to 100 parts by weight of the powder NBR used.
Parts by weight, 4 parts by weight of benzoyl peroxide, 500 parts by weight of ferrite, and 5 parts by weight of aromatic process oil were added, and the rotor was rotated at 800 rpm for 30 seconds at room temperature to uniformly mix them. Next, while rotating the rotary blade, n-
20 parts by weight of butyl acrylate, 1 part by weight of dimethylaniline, and 0.1 part by weight of hydroquinone monomethyl ether are added dropwise to a solution mixed for 1 minute, and mixed,
The mixture was further stirred for 30 seconds to obtain a room temperature curable elastic composition.

The obtained composition was passed through a 12 "roll forming machine manufactured by Nishimura Koki Co., Ltd. to be aggregated, and then a sheet having a thickness of 0.5 mm was formed by a reverse L8" calendar roll forming machine manufactured by Nishimura Koki Co., Ltd. . The obtained sheet was allowed to stand at room temperature for 24 hours to be cured, and then a tensile test was conducted according to JIS K 6301 in order to know the mechanical properties of the sheet.

Example 5 followed the same method as in Example 4 except that the n-butyl acrylate of Example 4 was changed to methyl methacrylate.

Comparative Example 2 uses the alpha-cumyl hydroperoxide shown in Formulation No. 2 of Example 2 of the low-temperature vulcanizable rubber composition of JP-A-49-66734 and cobalt abethienoate, and the prescribed values shown in Table 2 are used. The composition was kneaded using a 12 ″ roll forming machine, and then a sheet having a thickness of 0.5 mm was formed using a reverse L8 ″ calender roll forming machine. The sheet was left at room temperature for 10 days, and a tensile test was conducted in the same manner as in Example 4. As is clear from Table 2, it is clear that Examples 4 and 5 have higher tensile strength than Comparative Example 2, and as described above, Examples 4 and 5 were left at room temperature for 1 day. , 1/10 compared with Comparative Example 2.

Claims (1)

[Claims] 1. A rubber powder 100 having a particle size of at least 5 mm or less.
A room temperature curable elastic composition obtained by adding 0.1 to 50 parts by weight of an acrylate ester, 0.1 to 30 parts by weight of an organic peroxide, and 0.01 to 20 parts by weight of a decomposition accelerator of an organic peroxide, and agitating the mixture per parts by weight.