JP2844732B2 - Chlorinated acrylonitrile-butadiene copolymer rubber and method for producing the same - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a chlorinated acrylonitrile-butadiene copolymer rubber suitable for a rubber material for transporting a refrigerant, which has a low permeability of a refrigerant and a refrigerant gas, and a method for producing the same. .

[Related Art] A typical example of a rubber material for transporting a refrigerant is a cooler hose of an automobile. The required performance of such a cooler hose is that a refrigerant (fluorocarbon) and a refrigerant gas (fluorocarbon gas) have low permeation. Freon gas permeability)
Are listed.

It has been clarified that Freon gas R-12 (CCl ₂ F ₂ ), which has been generally used as a refrigerant, destroys the ozone layer in the upper part of the atmosphere, and switching from R-12 to R-22 (CHClF ₂ ) has been made. Is being promoted. However. R-22 has higher permeability to rubber materials than R-12. For this reason, vulcanized rubber materials mainly composed of acrylonitrile-butadiene copolymer rubber, which have been used so far, have insufficient permeation resistance to Freon gas R-22.

On the other hand, an acrylonitrile-butadiene copolymer rubber composition (Japanese Patent Publication No. 62-7793, Japanese Patent Application Laid-Open No. 58-17133) has been proposed in which the permeation of Freon gas is reduced. Permeability for them was not yet small enough.

Therefore, the permeation of Freon gas R-22 is extremely small,
Moreover, a new rubber hose material having flexibility (rubber elasticity) is strongly demanded.

[Problems to be Solved by the Invention] That is, an object of the present invention is to use Freon gas (R
-22) It is an object of the present invention to provide a copolymer rubber suitable for a rubber material for transporting a refrigerant, which has a sufficiently small permeability and has a necessary flexibility as a hose, and a method for producing the same.

Means for Solving the Problems The present inventors have conducted intensive studies on the development of such a rubber material, and as a result, have found that chlorinated acrylonitrile obtained by chlorinating acrylonitrile-butadiene copolymer rubber.
It has been found that butadiene copolymer rubber (except for chlorinated acrylonitrile-butadiene copolymer rubber obtained by partially chlorinating acrylonitrile-butadiene which has been partially hydrogenated) is a rubber material which achieves the above-mentioned objects and constitutes the present invention. It has been reached.

The acrylonitrile-butadiene copolymer rubber used in the present invention is a copolymer of acrylonitrile and 1,3-butadiene, or a copolymer obtained by partially replacing 1,3-butadiene with acrylic acid, methacrylic acid, itaconic acid, or the like. It is a united rubber and is usually produced by emulsion polymerization.

As the copolymer rubber of the present invention, acrylonitrile-
Examples thereof include a butadiene copolymer rubber and an acrylonitrile-butadiene-acrylic acid copolymer rubber, and an acrylonitrile-butadiene copolymer rubber is particularly suitable.

The content of bound acrylonitrile in the acrylonitrile-butadiene copolymer rubber of the present invention is preferably from 18 to 50% by weight, particularly preferably from 20 to 45% by weight.

Chlorinated acrylonitrile-butadiene copolymer rubber using acrylonitrile-butadiene copolymer rubber having a bound acrylonitrile content of less than 18% by weight (however, chlorinated acrylonitrile obtained by chlorinating partially hydrogenated acrylonitrile-butadiene) Butadiene copolymer rubber) cannot obtain the desired low fluorocarbon gas permeability. A chlorinated acrylonitrile-butadiene copolymer rubber using a acrylonitrile-butadiene copolymer rubber having a bound acrylonitrile content exceeding 50% by weight as a raw material (however, chlorinated acrylonitrile obtained by partially chlorinating acrylonitrile-butadiene) (Except for butadiene copolymer rubber) has low fluorocarbon gas permeability, but loses the flexibility required for a rubber hose.

The chlorinated acrylonitrile-butadiene copolymer rubber of the present invention (provided that partially hydrogenated acrylonitrile-
Chlorine content contained in chlorinated acrylonitrile-butadiene copolymer rubber obtained by chlorinating butadiene) is 5%
Preferably, it is between about 50% and 50% by weight. Particularly preferably, it is 5 to 45% by weight.

Chlorinated acrylonitrile having a chlorine content of less than 5% by weight
Butadiene copolymer rubber (except for chlorinated acrylonitrile-butadiene copolymer rubber in which partially hydrogenated acrylonitrile-butadiene is chlorinated) cannot obtain the desired low fluorocarbon gas permeability. Also,
Chlorinated acrylonitrile having a chlorine content exceeding 50% by weight
Butadiene copolymer rubber (except for chlorinated acrylonitrile-butadiene copolymer rubber in which partially hydrogenated acrylonitrile-butadiene is chlorinated) can provide the desired low fluorocarbon gas permeability, but is necessary for rubber hoses. You lose flexibility.

The chlorinated acrylonitrile-butadiene copolymer rubber of the present invention (provided that partially hydrogenated acrylonitrile-
The method of synthesizing chlorinated acrylonitrile-butadiene copolymer rubber obtained by chlorinating butadiene) is based on acrylonitrile-butadiene copolymer rubber as a raw material, using a radical generator as a catalyst, chlorine gas, chlorine gas and sulfuryl chloride or chloride. There is a method of reacting sulfuryl alone. Particularly preferred is a method of chlorination using chlorine gas alone.

The reaction may be performed in a homogeneous system dissolved in a solution, performed in a heterogeneous system suspended in a solution, or performed in a heterogeneous system released in a gas phase. However, a homogeneous acrylonitrile-butadiene copolymer rubber obtained by dissolving a raw material acrylonitrile-butadiene copolymer rubber in a solvent is a chlorinated acrylonitrile-butadiene copolymer rubber having sufficiently low CFC gas permeability (however, partially hydrogenated acrylonitrile). (Except for chlorinated acrylonitrile-butadiene copolymer rubber obtained by chlorinating butadiene), a more excellent method is desirable.

At this time, as a reaction solvent, a solvent inert to a chlorination reaction such as chloroform, carbon tetrachloride, dichloroethane, trichloroethane, tetrachloroethane, monochlorobenzene, dichlorobenzene, fluorobenzene, dichlorodifluoromethane, trichlorofluoromethane, etc. Is used. Particularly, in the case of chloroform, chlorinated acrylonitrile-butadiene copolymer rubber (except for chlorinated acrylonitrile-butadiene copolymer rubber obtained by partially chlorinating acrylonitrile-butadiene) may be precipitated during the chlorination reaction. Preferred.

The amount of the acrylonitrile-butadiene copolymer rubber to be dissolved is preferably 0.2 to 10% by weight.

When the content exceeds 10% by weight, not only is it extremely difficult to control the chlorination reaction, but also the chlorinated acrylonitrile-butadiene copolymer rubber (provided that partially hydrogenated acrylonitrile-butadiene is used). Some of the chlorinated chlorinated acrylonitrile-butadiene copolymer rubber) gels (insoluble in the reaction solvent).
If less than 0.2% by weight, a large amount of solvent is required,
Productivity significantly deteriorates due to problems such as removal from the reactants.

After completion of the chlorination reaction, the hydrogen chloride remaining in the solution is removed from the system by blowing an inert gas such as nitrogen under reflux of the solvent.

The obtained chlorinated acrylonitrile-butadiene copolymer rubber (provided that partially hydrogenated acrylonitrile-
The solution of chlorinated acrylonitrile-butadiene copolymer rubber obtained by chlorinating butadiene) is separated into rubber and solvent by 1) steam distillation 2) drum drying 3) extrusion drying.

1) is a method of feeding a polymer solution into hot water (see US Pat. No. 2,592,814).

2) A method in which a polymer solution is fed to a heated rotating drum surface to take out the polymer as a film (see US Pat. No. 2,923,795).

The method 3) is a method in which the reaction solution is pre-concentrated and then fed to a vent extrusion dryer for separation. (JP-A-57-4730
3).

In the present invention, separation and drying can be performed by any of the following processes.

The chlorinated acrylonitrile-butadiene copolymer rubber of the present invention (provided that partially hydrogenated acrylonitrile-
Chlorinated acrylonitrile-butadiene copolymer rubber obtained by chlorinating butadiene) is used as an unvulcanized product in the same manner as a conventional acrylonitrile-butadiene copolymer rubber.
Alternatively, it is vulcanized together with a vulcanizing agent, a vulcanization accelerator, a filler, a stabilizer and the like and used as a vulcanized product.

As the vulcanizing agent, vulcanization accelerator, filler, stabilizer and the like, those currently used for acrylonitrile-butadiene copolymer rubber, chlorinated polyethylene, and chlorosulfonated polyethylene are used.

As the vulcanizing agent, sulfur and organic peroxide are known. Vulcanization accelerators include tetramethylthiuram disulfide (TT), dibenzothiazyl disulfide (DM),
Dipetamethylene thiuram hexasulfide (TRA),
2-mercaptoimidazoline (# 22) and the like. Zinc oxide is used as a vulcanization accelerator. Fillers include charcoal, crew, silica, oil softener, carbon black and the like.

These are compounded and kneaded with a roll or a Banbury mixer in the same manner as the acrylonitrile-butadiene copolymer rubber, and then subjected to press vulcanization, steam vulcanization, UHF vulcanization and the like.

EXAMPLES Next, the present invention will be described in more detail based on examples, but these are examples for helping to understand the present invention, and the present invention is not limited by these examples.

The values used in these examples were obtained in accordance with the following measurement methods.

Chlorine content: Combustion flask method Bound nitrile content: JIS K 6384 Mooney viscosity: JIS K 6300 (ML1 + 4,100 ° C) Vulcanized rubber properties: JIS K 6301 Freon gas (R-22) permeation test is performed by different pressure method and permeation of Freon gas The rate (Q) and the CFC permeation coefficient (P) were determined. The different pressure method is a measurement method based on ASTM D-1434-75M and is shown below.

A 600 μm thick rubber sheet was attached to a permeation cell installed in a thermostat. One of the cells has 1 atm of chlorofluorocarbon (R
−22), and the other was left under vacuum. The amount of permeated CFC gas for a certain time was determined from the pressure change.

The flexibility of the rubber was determined by bending the vulcanized rubber sheet obtained by kneading the roll with the compounding disposal shown in Table 1, pressurizing and heating at 150 ° C for 30 minutes.

Example-1 35 g of an acrylonitrile-butadiene copolymer rubber (manufactured by Zeon Corporation: DN-2) was placed in a 10 L autoclave equipped with a stirrer.
19, bound acrylonitrile: 33% by weight) was dissolved in 7000 g of chloroform. The chlorination reaction was carried out at 15 ° C. by blowing chlorine gas at a flow rate of 40 ml / min for 145 minutes. After the completion of the reaction, while maintaining the reaction solution at 15 ° C., the flow rate of nitrogen was 11
The remaining hydrogen chloride was removed by blowing at / min for 120 minutes.

Thereafter, the reaction solution was fed to a drum dryer to separate the reaction product from the solvent.

Analysis showed that the chlorinated acrylonitrile-butadiene copolymer rubber contained 25% by weight of chlorine.

 The Mooney viscosity was 107.

Using an 8-inch roll heated to 40 ° C, the roll was kneaded by the compounding treatment shown in Table 1. Press vulcanization was performed at 150 ° C. for 30 minutes to obtain a vulcanized rubber sheet.

Table 2 shows the evaluation results of the physical properties of the vulcanized rubber, the rubber flexibility, and the fluorocarbon gas permeability.

Example 2 Acrylonitrile-butadiene copolymer rubber (manufactured by Zeon Corporation: DN-105, amount of bound acrylonitrile: 42% by weight)
And chlorinated in the same manner as in Example 1. However, the blowing time of chlorine was set to 65 minutes. After the completion of the reaction, the reaction product was separated from the solvent in the same manner as in Example-1.

Analysis revealed that the chlorinated acrylonitrile-butadiene copolymer rubber contained 14% by weight of chlorine.

Roll kneading was performed in the same manner as in Example 1 to obtain a vulcanized rubber sheet. Table 2 shows the physical property evaluation results.

Comparative Example-1 Acrylonitrile-butadiene copolymer rubber (manufactured by Zeon Corporation: DN-209, bound acrylonitrile amount: 33% by weight)
And chlorinated in the same manner as in Example 1. However, the blowing time of chlorine was 15 minutes. After the completion of the reaction, the reaction product was separated from the solvent in the same manner as in Example-1.

Analysis revealed that the chlorinated acrylonitrile-butadiene copolymer rubber contained 2% by weight of chlorine.

Roll kneading was performed in the same manner as in Example 1 to obtain a vulcanized rubber sheet. Table 2 shows the physical property evaluation results.

Comparative Example-2 Acrylonitrile-butadiene copolymer rubber (manufactured by Zeon Corporation: DN-105, amount of bound acrylonitrile: 42% by weight)
And chlorinated in the same manner as in Example 1. However, the blowing time of chlorine was 15 minutes. After the completion of the reaction, the reaction product was separated from the solvent in the same manner as in Example-1.

As a result of the analysis, it was found that the chlorinated acrylonitrile-butadiene copolymer rubber contained 3% by weight of chlorine.

Roll kneading was performed in the same manner as in Example 1 to obtain a vulcanized rubber sheet. Table 2 shows the physical property evaluation results.

[Effect of the Invention] The chlorinated acrylonitrile-butadiene copolymer rubber (except for the chlorinated acrylonitrile-butadiene copolymer rubber obtained by chlorinating partially hydrogenated acrylonitrile-butadiene) obtained by the present invention is represented by R -22 This is a novel rubber material with extremely low permeation of CFC gas and flexibility (rubberiness).

Therefore, it is suitable as a rubber material for transporting refrigerant such as a cooler hose of an automobile.

Claims (2)

(57) [Claims] 1. A chlorinated acrylonitrile-butadiene copolymer rubber having a chlorine content of 5 to 50% by weight and a bound acrylonitrile content of 18 to 50% by weight, provided that a partially hydrogenated acrylonitrile-butadiene is chlorinated. Chlorinated acrylonitrile-butadiene copolymer rubber). 2. The method according to claim 1, wherein the bound acrylonitrile content is 18 to 50% by weight.
The method for producing a chlorinated acrylonitrile-butadiene copolymer rubber according to claim 1, wherein the acrylonitrile-butadiene copolymer rubber is chlorinated to have a chlorine content of 5 to 50% by weight.