JPS6053547A - Low-odor rubber - Google Patents

Abstract

PURPOSE:To provide a rubber composition free from the emission of odor during use, by compounding a rubbery polymer with a polymer and/or an inorganic filler having an acidic functional group, a vulcanizing agent and a vulcanization accelerator. CONSTITUTION:100pts.wt. of a rubbery polymer is compounded with 5- 30pts.wt. of a polymer and/or inorganic filler having acidic functional group, 0.5-2pts.wt. of a vulcanizing agent (sulfur) and 0.3-2pts.wt. of a vulcanization accelerator (a thiuram or dithiocarbamic acid salt accelerator wherein the amine produced by the decomposition during the vulcanization is a low-boiling amine such as dimethylamine, diethylamine, etc.). The rubbery polymer is preferably EPDM. The inorganic filler is preferably magnesium oxide, etc. having particle diameter of 5-20mu. The vulcanization accelerator is preferably combined with dibenzothiazyl sulfide or 2-mercaptobenzothiazole.

Description

[Detailed Description of the Invention] (Purpose and Background) Generally, vulcanized rubber products have a unique odor, so they are used in indoor products that dislike odors, and for transporting and storing water for daily life where migration of this odor is a problem. It was difficult to use it for products that were exposed to water, such as rubber hoses for water supply and rubber tanks for solar power. The object of the present invention is to provide a low-odor rubber that eliminates these drawbacks.

Until now, there has been no clear knowledge as to what components are responsible for the unique odor found in rubber products.

As a result of measuring the odor of various rubber products using a gas chromatograph, the present inventors found that the overwhelming majority of odor components in rubber products are amines produced when vulcanization accelerators decompose. However, almost all organic vulcanization accelerators contain nitrogen in their molecules, which decompose during vulcanization to form amines. Therefore, it is difficult to prevent the formation of amines in the formulation.

Therefore, the wood inventors tried to volatilize the produced amine as much as possible during vulcanization, and make it non-volatile by some method after vulcanization, so that the amine would not come out of the Goto product within the operating temperature range. If so, I think it might be possible to prevent the odor from occurring during use.1/) U, jQ ;u! 1: As a result of repeated research based on this, the present invention has been achieved.

(Structure) That is, the present invention vulcanizes a rubber composition in which a polymer having an acidic functional group and/or an inorganic filler, a vulcanizing agent, and a vulcanization accelerator are blended into a rubbery polymer (11). It is a low odor rubber.

As the rubbery polymer, natural rubber or polybutadiene rubber (BR), polyisoprene = 11. (IR), styrene-butadiene com (SI31i), butyl rubber (
IIR), halogenated butyl rubber 1\, chloroprene, acrylic rubber, butadiene-ac IJ ronitrile rubber (N
Synthetic rubbers such as BR), ethylene-propylene rubber (EPR), ethylene-propylene terpolymer (EPDM), or blends thereof, are selected arbitrarily, but among them, the rubber has excellent weather resistance, chemical resistance, and other comprehensive properties. EPDM is preferable in this respect.

Examples of polymers having acidic functional groups include the following.

a) A copolymer of an olefin such as ethylene or propylene and an unsaturated carboxylic acid such as acrylic acid, methacrylic acid or maleic acid, or a polymer partially neutralized with a metal.

b) For diene polymers, nylon, rayon, etc.
A polymer in which unsaturated carboxylic acid is graft-polymerized.

When the main chain is a diene polymer, it is called carboxyl rubber.

C) A cation exchange resin having a sulfone buty group, a carboxyl group, and a phenolic hydroxyl group.

As the inorganic filler, magnesium oxide, aluminum hydroxide, and clay are preferred. In addition, the particle size of these particles is 1 to
100 pL, especially 5 to 20 ml is preferred.

In the present invention, one or both of the polymer having an acidic functional group and the S filler are blended into the rubbery polyester, and the blending amount is based on 100 parts by weight of the rubbery polymer. It is preferably in the range of 5 to 30 parts by weight. If the amount is more than this, the effect will be small, and if it is added more than this, the properties of the rubber will be impaired, such as poor thermal strain recovery. These polymers or inorganic fillers having acidic functional groups function to fix the amine remaining after vulcanization and prevent the amine from being liberated within the temperature range in which the rubber product is used.

Sulfur is usually used as a vulcanizing agent, and
It is preferable to mix 0.5 to 2 parts by weight per 00 parts by weight.

As the vulcanization accelerator, any practically used vulcanization accelerator can be used, but the following are particularly preferred.

a) A thiuram accelerator in which the amine decomposed and produced during vulcanization is a low-boiling amine such as dimethylamine or diethylamine, i.e., tetramethylthiuram disulfide (TT).
), tetraethylthiuram disulfide (TET),
Tetramethyldiuram monosulfide (TS), etc.

b) Anti-thiocarpamate accelerators whose amines decomposed and produced during vulcanization are low-boiling amines such as dimethylamine and diethylamine, i.e. dimethyldithiocarbamine anti-corrosion (TTCU), zinc dinotyldithiocarbamate (PZ);
), zinc diethyldithiocarbamate (EZ), sodium dimethyldithiocarbamate (S), sodium diethyldithiocarbamate (SDC), ferric dimethyldithiocarbamate (TTFE), etc.

These are preferable because the amine produced by decomposition has a low boiling point and most of it evaporates during vulcanization.

As the vulcanization accelerator, one selected from the above two types may be used alone;
DM) and 2-mercaptobenzothiazole (M) are preferred in order to obtain good vulcanization properties.

The blending amount of the vulcanization accelerator is rubbery polymer i o o Bl
It is preferable that kf be 0.3 to 2 parts by weight per part (1).

In addition to the respective ingredients, reinforcing agents, anti-fog + L agents, 7□ colorants, and other ingredients that are normally used in the production of rubber products may be optionally blended.

As mentioned at the beginning, the low-odor rubber of the present invention is aimed at not emitting any odor even when used in rubber hoses for water supply or goto tanks for solar power. Chlorine, hypochlorous acid, hypochlorous acid sorter, etc. are added for sterilization purposes, and it contains active chlorine ions.

In order to increase the resistance to water containing active 1 s 1 element, pH
It is effective to use one with a rating of 7 or less. Examples of the 4Φ carphone blank include a channel blank having a pH of 4 to 6, and a so-called color carbon blank obtained by surface-treating a furnace blank to have a pH of 7 or less.

The amount of carbo black to be blended is 0.3 to 150 parts by weight, preferably 12 parts by weight, preferably 5 to 100 parts by weight, per 100 parts by weight of the carbo black.

The vulcanization method may be mold, press, steam, or hot air, but hot air vulcanization is particularly effective.

Examples In the following Examples and Comparative Examples, the basic formulations shown in Table 1 were used as common ingredients, with emphasis on continuous vulcanization using hot air. However, the effects of the present invention are not limited to this formulation. In the table, "parts j" are all parts by weight.

Vulcanization was carried out by leaving it in hot air at 200°C for 300 minutes.

Amine amount i! The +11 constant was obtained by adjusting the surface area of the rubber to 8000 cm2/text relative to the amount of water, immersing it in water, keeping it at 80°C for 2 hours, and then leaving it to cool. The content of amines contained in water was measured using a gas chromatograph. The odor of this water was also evaluated.

Table 1 Examples 1-2. Comparative Examples 1 to 3 The effect of blending a polymer with a resistant functional group is f? J'
; Shown in Table 1.

As seen in Examples 1 and 2, the addition of the ethylene-acrylic acid copolymer resulted in rubber vulcanization of 11! It can be seen that the amount of amine extracted from the rubber can be reduced without significantly affecting the physical properties of the rubber, and that the odor is reduced in proportion to the amount of amine.

Examples 3-5. Comparative example 4 Table 3 shows the effects of adding inorganic fillers.

Table 2 Table 3 As seen in Examples 3-5, magnesila oxide IN.

Clay and aluminum hydroxide were found to have an odor trapping effect.

Examples 6-7. Comparative Example 5 Table 4 shows the effects of a polymer having an acidic functional group and an inorganic additive.

As shown in Example 6, no odor was observed when the ethylene/acrylic acid copolymer and aluminum hydroxide were used together.

Furthermore, in Example 7, when thiazole-based nodibenzothiazyl disulfide (DM) and thiuram-based left tramethylthiuram disulfide F (TT) were used together as vulcanization accelerators, a polymer having an acidic functional group This shows that the odor can be reduced without substantially impairing the strength of the rubber even if it is added.

Applicant: Brideston Tire Co., Ltd. Agent Patent Attorney Masaaki Ao

Claims (1)

[Claims] 1. Low odor obtained by vulcanizing a rubber composition in which a rubbery polymer is blended with a polymer having an acidic functional group and/or an inorganic filler, a vulcanizing agent, and a vulcanization accelerator. rubber. 2. The low odor according to claim 1, wherein the polymer having an acidic functional group and/or the inorganic filler are blended in an amount of 5 to 30 parts by weight based on 100 parts by weight of the rubbery polymer. rubber. 3. Sulfur is used as a vulcanizing agent in an amount of 0.5 to 2 parts by weight per 100 parts by weight of the rubbery polymer, and as a vulcanization accelerator, amines generated by decomposition during vulcanization are low boiling point amines such as dimethylamine and diethylamine. Thiuram type or dithiocarbamine butylene 11! The low odor according to claim 1 or 2, wherein at least one selected from system accelerators is blended in an amount of 0.3 to 2 parts by weight based on the amount of gono, l Oo and tun Ja parts. sex rubber.