JP2001049020A - Blowing agent composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition which has no impact on the environment and is highly safe and cheap and which yields a foamed article having excellent strength by blending azodicarbonamide, a metal salt of an aromatic sulfinic acid and a dithiocarbamate. SOLUTION: Preferably 1 pts.wt. of azodicarbonamide which has desirably a particle diameter of 1-50 μm, preferably 0.01-1 pts.wt. of a metal salt of an aromatic sulfinic acid and preferably 0.01-1 pts.wt. of a dithiocarbamete are blended. The blowing agent composition does not generate ammonia nor discolor metal materials. As the metal salt of the aromatic sulfinic acid, a Na salt, a K salt, a Ca salt or a Zn salt is desirable, and zinc dibenzenesulfinate is especially desirable. As the dithiocarbamate, its Zn salt is desirable, and zinc dimethyldithiocarbamate is especially desirable. The blowing agent composition is suitable for foaming rubber materials and yields a foamed article which is unlikely to undergo reversion and has excellent strength.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a foaming agent composition, particularly to a foaming agent composition suitable for rubber foaming and which does not generate ammonia.

[0002]

2. Description of the Related Art As foaming agents for foaming rubber, azodicarbonamide (ADCA), N, N'-dinitrosopentamethylenetetramine (DPT), p, p'-oxybis (benzenesulfonylhydrazide) (OBSH) are known. , P-
Various chemical blowing agents such as toluenesulfonyl hydrazide (TSH) are known.

[0003]

Among these, the DPT
Has a disadvantage that it is inferior in safety to the human body because it has a danger of explosion and fire and is suspected to be a mutagen. Furthermore, when using DPT, it is practically essential to use urea as a decomposition accelerator, ammonia generated from the urea is not environmentally and operationally unfavorable, and metals and metal-containing paints (for example, aluminum powder) are used. (Metallic paints for automobiles, etc., containing the same).
Further, OBSH and TSH are expensive compounds and have a drawback that they are inferior in economical efficiency because they generate a small amount of gas.

On the other hand, ADCA is a compound which is inexpensive, generates a large amount of gas, and is excellent in safety. However, its decomposition temperature is as high as about 200 ° C., and in consideration of vulcanization, it is relatively low (120 ° C.). (160 ° C.) is difficult to use alone as a foaming agent for rubber foaming which requires a decomposition temperature. Therefore, urea, a zinc compound, a lead compound, a cadmium compound and the like are blended with ADCA and used as a decomposition accelerator. However, among these compounds, urea has problems such as the above-mentioned environment, work problems and metal discoloration due to the generation of ammonia. There is a problem that it is not suitable for temperature.

On the other hand, benzenesulfinic acid metal salt is AD
It is known to act as an excellent accelerator for the decomposition of CA. For example, JP-A-10-53756 discloses ADCA,
Although a blowing agent composition containing benzenesulfinic acid salt and urea is described, when it is blended with rubber, it recurs (when the rubber is vulcanized, the point once crosslinked due to the effect of additives, etc., breaks again. Phenomena) and the physical properties of the rubber deteriorate. Dithiocarbamate is generally known as a vulcanization accelerator for rubber.
When used in combination with DCA, there is a problem that only a low expansion ratio can be obtained.

SUMMARY OF THE INVENTION An object of the present invention is to provide a foaming agent composition which is environmentally friendly, can be produced with high safety, is inexpensive and has excellent strength, and is particularly suitable for rubber foaming and does not generate ammonia. To provide. Another object of the present invention is to provide a rubber foam which is excellent in strength, suppresses generation of ammonia gas, and does not cause discoloration of an adjacent metal material.

[0007]

SUMMARY OF THE INVENTION The present invention relates to a blowing agent composition containing azodicarbonamide, a metal salt of aromatic sulfinic acid and a dithiocarbamate. The present invention also relates to a rubber foam foamed with the foaming agent composition. In the present invention, since a dithiocarbamate is used in combination with the metal salt of aromatic sulfinic acid in ADCA, a foam having excellent strength with less reversion is obtained. In addition, there is no generation of ammonia, which is favorable from the viewpoint of environment and work, and does not cause discoloration of the metal material.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The ADCA used in the present invention is not particularly limited, and those manufactured by various manufacturing methods can be used. The particle size is also not particularly limited, but usually a particle size of about 1 to 50 μm can be preferably used.

Specific examples of the metal salt of aromatic sulfinic acid used in the present invention include sodium benzenesulfinate, potassium benzenesulfinate, lithium benzenesulfinate, calcium dibenzenesulfinate, lead dibenzenesulfinate, dibenzenesulfinate. Barium acid, cadmium benzenesulfinate, magnesium dibenzenesulfinate, sodium p-toluenesulfinate, potassium p-toluenesulfinate, lithium p-toluenesulfinate, zinc bis-p-toluenesulfinate, bis-p-toluenesulfine Calcium acid, lead bis-p-toluenesulfinate, bis-p-
Barium toluenesulfinate, cadmium bis-p-toluenesulfinate, magnesium bis-p-toluenesulfinate, sodium p-chlorobenzenesulfinate, potassium p-chlorobenzenesulfinate, p
-Lithium chlorobenzenesulfinate,

[0010] Zinc bis-p-chlorobenzenesulfinate, calcium bis-p-chlorobenzenesulfinate, lead bis-p-chlorobenzenesulfinate, bis-
Barium p-chlorobenzenesulfinate, bis-p-
Cadmium chlorobenzenesulfinate, magnesium bis-p-chlorobenzenesulfinate, sodium 2,4-dimethylbenzenesulfinate, potassium 2,4-dimethylbenzenesulfinate, lithium 2,4-dimethylbenzenesulfinate, bis-2,4- Zinc dimethylbenzenesulfinate, calcium bis-2,4-dimethylbenzenesulfinate, lead bis-2,4-dimethylbenzenesulfinate, barium bis-2,4-dimethylbenzenesulfinate, bis-2,4-dimethylbenzene Cadmium sulfinate, magnesium bis-2,4-dimethylbenzenesulfinate, sodium 2,5-dimethylbenzenesulfinate,

Zinc bis-2,5-dimethylbenzenesulfinate, sodium 3,4-dimethylbenzenesulfinate, zinc bis-3,4-dimethylbenzenesulfinate, sodium 2-chloro-4-methylbenzenesulfinate, bis Zinc-2-methyl-4-chlorobenzenesulfinate, sodium p-fluorobenzenesulfinate, zinc bis-p-fluorobenzenesulfinate, sodium p-bromobenzenesulfinate, zinc bis-p-bromobenzenesulfinate, p- Sodium tert-butylbenzenesulfinate, bis-p
Zinc tert-butylbenzenesulfinate, zinc bis-2,3,4,5,6-pentamethylbenzenesulfinate and zinc bis-2,3,4,5,6-pentachlorobenzenesulfinate.

Of these metal salts of aromatic sulfinic acids, sodium salts, potassium salts, calcium salts and zinc salts are preferred, and zinc dibenzenesulfinate is particularly preferred. The amount of the metal salt of the aromatic sulfinic acid to be used is preferably 0.01 to 1 part by weight per 1 part by weight of ADCA, but is not limited thereto.

The dithiocarbamates used in the present invention include zinc diethyldithiocarbamate, zinc dipropyldithiocarbamate, zinc dibutyldithiocarbamate, zinc diamyldithiocarbamate, zinc dibenzyldithiocarbamate, zinc N-pentamethylenedithiocarbamate, Zinc ethylphenyldithiocarbamate, zinc hexadecylisopropyldithiocarbamate, zinc octadecylisopropyldithiocarbamate, complex salts of zinc dibutyldithiocarbamate and dibutylamine, complex salts of zinc pentamethylenedithiocarbamate and piperidine, sodium dimethyldithiocarbamate, sodium diethyldithiocarbamate, dibutyl Sodium dithiocarbamate, sodium pentamethylenedithiocarbamate Sodium dibenzyl dithiocarbamate, potassium dimethyl dithiocarbamate,

Ammonium diethyldithiocarbamate, dimethylammonium dimethyldithiocarbamate, dibutylammonium dibutyldithiocarbamate, piperidine pentamethylenedithiocarbamate, pipecoline pipepecolyldithiocarbamate, N, N'-dimethylcyclohexylamine dibutyldithiocarbamate, selenium dimethyldithiocarbamate, Selenium diethyldithiocarbamate, tellurium diethyldithiocarbamate, cadmium diethyldithiocarbamate, cadmium diamyldithiocarbamate, cadmium pentamethylenedithiocarbamate, copper dimethyldithiocarbamate, copper pentamethylenedithiocarbamate, ferric dimethyldithiocarbamate, bismuth dimethyldithiocarbamate, Dimethyldiethyl Zinc carbamate, diamyldithiocarbamate lead, N- pentamethylene dithiocarbamate, lead activated dithiocarbamate, dithiocarbamate reaction Hinto can be exemplified.

Of these, zinc salts are preferred, and zinc dimethyldithiocarbamate is particularly preferred. The amount of the dithiocarbamate used is preferably 0.01 to 1 part by weight with respect to 1 part by weight of ADCA, but is not limited thereto.

In the present invention, ADCA is mixed with a dithiocarbamate together with a metal salt of aromatic sulfinic acid, so that reversion, which occurs when only a metal salt of aromatic sulfinic acid is used, does not easily occur, and the strength is excellent. Foam can be obtained. In addition, since the blowing agent composition of the present invention does not use urea, the generation of ammonia gas during decomposition is significantly suppressed, and the generation of ammonia gas from a foam obtained using the same hardly occurs. The problem of discoloration of metals and metal-containing paints was solved.

The foaming agent composition of the present invention may contain other components in addition to the above-mentioned effective components as long as the effects of the present invention are not impaired. Such components include stabilizers, pigments / fillers, foam inhibitors, oils and fats, coupling agents, sulfur, vulcanization accelerators, vulcanizing agents, anti-aging agents, mastication accelerators, anti-scorch agents, processing Auxiliaries and the like.

As the stabilizer, for example, tribasic lead sulfate,
Examples include dibasic phosphite, lead stearate, zinc stearate, zinc carbonate, zinc oxide, barium stearate, aluminum stearate, calcium stearate, dibutyltin malate, and urea. Examples of pigments and fillers include chrome yellow, carbon black, white carbon, titanium dioxide, calcium carbonate, and the like. Further, examples of the foaming inhibitor include maleic acid and the like.

The fats and oils include liquid or solid fats and oils,
Examples of hydrocarbons and fatty acids include oils and fats such as soybean oil, coconut oil, linseed oil, cottonseed oil, rapeseed oil, drill oil, pine oil, rosin, castor oil, beef tallow, squalane, lanolin, and hardened oil. Examples include vegetable or animal natural fats and oils and their purified products. Further, as the hydrocarbons, those having 20 carbon atoms, which are collectively called paraffin wax, are used.
~ 48 aliphatic hydrocarbons and derivatives thereof, having 8 to 8 carbon atoms
19 aliphatic hydrocarbons and derivatives thereof (eg, dialkyl phthalates such as dioctyl phthalate, higher alcohol phthalates such as nonyl alcohol phthalate, etc.), paraffinic, naphthenic or aromatic process oils, and liquid paraffin. Can be Fatty acids include, for example, fatty acids such as lauric acid, myristic acid, balmitic acid, stearic acid, oleic acid, and behemic acid, and salts or derivatives thereof.

Examples of the coupling agent include silane coupling agents such as aminopropyltriethoxysilane and N-β (aminoethyl) γ-aminopropyltrimethoxysilane, and aluminum tris (ethylacetoacetate).
And the like, and an aluminum-based coupling agent and a titanate-based coupling agent. Examples of the vulcanization accelerator include hexamethylenetetramine (H), n-butyraldehydeaniline (8), 1,3-diphenylguanidine (D),
-Mercaptobenzothiazole (M), dibenzothiazyldisulfide (DM), 2-mercaptobenzothiazole zinc salt (MZ), tetramethylthiuram disulfide (TT) and the like. As an anti-aging agent, poly (2,2,4-trimethyl-1,2-dihydroquinoline)
(RD), a reaction product (B) of diphenylamine and acetone, a diphenylamine derivative (OD) and the like. Examples of the processing aid include a mixture of a high molecular weight fatty acid ester and an unsaturated filler (for example, Exton K1, Exton L-2, etc.).

The foaming agent composition of the present invention can be used for foaming various resins and rubbers, and is particularly suitable for foaming rubbers. Specific examples of such a rubber include various natural rubbers, NBR (nitrile rubber), BR (butadiene rubber), SBR (styrene / butadiene rubber), CR (chloroprene rubber), IIR (butyl rubber), CIIR
(Chlorinated butyl rubber), IR (polyisoprene rubber),
Examples include synthetic rubbers such as ACM (acrylic rubber), styrene rubber, and EPDM (ethylene-propylene-diene copolymer).

The method for foaming rubber using the foaming agent composition of the present invention is not particularly limited, and various known production methods can be used. For example, rubber and the foaming agent composition of the present invention can be used. Other components to be compounded as necessary are mixed in a kneader, and further kneaded with a roll to form a rubber composition, which is then extruded by an extruder, and then subjected to a hot air continuous vulcanization / foaming device (H
a method of simultaneously performing vulcanization and foaming by ot Air Vulcanization) to obtain a rubber foam, and sequentially adding the foaming agent composition of the present invention and other components blended as necessary to the rubber after mastication, After forming a sheet-shaped rubber composition, a method of charging a mold and sequentially performing primary foaming at a relatively low temperature and secondary foaming at a relatively high temperature to obtain a rubber foam can be exemplified.

The rubber foam of the present invention thus obtained is
Since it is excellent in strength and hardly generates ammonia gas, it can be suitably used, for example, as a material for automobile parts and a material for electric and electronic parts.

[0024]

The present invention will be described in more detail with reference to the following Examples and Comparative Examples, but it should not be construed that the invention is limited thereto.

Examples 1 to 4 and Comparative Examples 1 and 2 After uniformly blending the compounds shown in Table 1 with a high-speed mixer,
g is precisely weighed and placed in a 30 ml round bottom flask. afterwards,
The silicone oil bath is decomposed under the conditions of 160 ° C. and 180 ° C. using the gas collecting device shown in FIG. When decomposition is complete, remove the round bottom flask from the silicone oil bath and cool to room temperature. After cooling, the amount of gas
C. and 1 atm. The amount of ammonia generated was determined by applying the mixture shown in Table 1 to the burette of the gas trapping unit.
The gas is decomposed in a 50 ml hydrochloric acid solution adjusted to pH = 1.5 under the conditions of 160 ° C. and 180 ° C., and the generated gas is bubbled. Even after the decomposition is completed, nitrogen gas is flowed into the round bottom flask for 10 minutes,
After bubbling and collecting all the ammonia in the gas,
The solution was quantified for ammonia ions by ion chromatography to determine the amount of generated ammonia. Table 2 shows the obtained gas generation amount, ammonia generation amount, and decomposition temperature of each composition obtained by the thermal analysis method. From Table 2, it can be seen that the composition of the present invention has a small amount of generated ammonia and has a decomposition temperature effective for rubber foaming.

[0026]

[Table 1]

Note 1: Uniform AZ V-45 [manufactured by Otsuka Chemical Co., Ltd.] Note 2: Cell Mic A [manufactured by Sankyo Chemical Co., Ltd.] Note 3: Zinc dibenzenesulfinate Note 4: Sodium benzenesulfinate Note 5 : Zinc dimethyl dithiocarbamate * 6: Zinc diethyl dithiocarbamate * 7: Uniform AZ 01 [Fine powder treated with fatty acid, manufactured by Otsuka Chemical Co., Ltd.]

[0028]

[Table 2]

Examples 5 to 6 and Comparative Examples 3 to 4 Materials of A in Table 3 were converted into rubber compounds using a Banbury mixer. Next, the material of B was added by an open roll and mixed for 10 minutes, and then removed from the roll as a 3.5 mm thick sheet to obtain a rubber sheet. After inserting the obtained sheet into a mold having a thickness of 7 mm and setting the mold in a hot press adjusted to 160 ° C. and 180 ° C. in advance,
Vulcanization and foaming were performed by heating for 20 minutes under a pressure such that there was no gap between the press hot plate and the mold. Table 4 shows the vulcanization characteristics of the composition, the performance of the foam after vulcanization and foaming, and the discolored state of the aluminum-containing paint by the foam.

[0030]

[Table 3]

Note 8: Mitsui EPT 4095 [manufactured by Mitsui Petrochemical Industry Co., Ltd.] Note 9: SRF-Asahi # 35 [manufactured by Asahi Carbon Co., Ltd.] Note 10: Nobelite TT [manufactured by Nitto Powder Chemical Industry Co., Ltd.] Note 11: Shellflex 22R [manufactured by Shell Japan Ltd.] Note 12: Exton K-1 [manufactured by Kawaguchi Chemical Co., Ltd.] Note 13: Noxeller MZ [manufactured by Ouchi Shinko Co., Ltd.] Note 14: Noxeller M [ Note 15: Noxeller TT [manufactured by Ouchi Shinko Co., Ltd.] Note 16: Uniform AZ V-45 [manufactured by Otsuka Chemical Co., Ltd.] Note 17: Cell microphone A [Sankyo Chemical Co., Ltd.] Note 18: Uniform AZ 01 (fatty acid treated fine powder urea, manufactured by Otsuka Chemical Co., Ltd.) Note 19: Zinc dibenzenesulfinate Note 20: Sodium benzenesulfinate Note 21: Zinc dimethyl dithiocarbamate 22: diethyl zinc dithiocarbamate

[0032]

[Table 4]

Note 23: (volume of rubber foam-volume of mold) ×
1000 / Die volume Note 24: Specific gravity of rubber sheet composition / Specific gravity of rubber foam Note 25: JIS K 6262 (Permanent strain test method for vulcanized rubber and thermoplastic rubber) Note 26: Spring catasa test Type C measurement Note 27: JIS K6251 (Tensile test method for vulcanized rubber), dumbbell No. 3 type Note 28: JIS K6251 (Tensile test method for vulcanized rubber), Dumbbell No. 3 type Note 29: JIS K6251 ( Tension test method for vulcanized rubber), dumbbell-shaped No. 3 Note 30: Paint for aluminum-containing automobile repair (Body Pen T-168, manufactured by Soft 99 Corporation) on electrodeposited steel sheet, and dry. The 10 × 10 cm square rubber foams of Examples 5 to 6 and Comparative Examples 3 and 4 were stuck to the painted surface and left at 70 ° C. for 72 hours. Thereafter, the rubber foam was removed and immersed in warm water of 50 ° C. for 24 hours. After wiping off the water, it was visually observed and evaluated. ：: Discoloration slightly on the black side △: Discoloration of black was conspicuous From Table 4, there is no large difference in Examples and Comparative Examples in general, but in Examples, compression set was small and physical properties were improved. It turns out that the discoloration of the paint is slight.

Example 7 and Comparative Examples 5 to 9 A rubber sheet was obtained in the same manner as in Examples 5 to 6, except that the composition shown in Table 5 was used as a foaming agent. The obtained sheet was similarly vulcanized and foamed at 160 ° C., and the results are shown in Table 5. The reversion was comprehensively evaluated from the values of the curast width, the compression set, and the strength physical properties.

[0035]

[Table 5]

From Table 5, clear reversion was observed in the system containing only the metal salt of aromatic sulfinic acid such as BSZ (Comparative Example 5). Further, an addition system containing only a dithiocarbamate such as DMT-Zn and DBT-Zn (Comparative Examples 6 and 7)
Did not sufficiently increase the expansion ratio. The cause is DMT-
It is considered that only Zn or DBT-Zn did not sufficiently lower the decomposition temperature of the addition system, and the decomposition of the foaming agent was insufficient. In the system in which urea was added to ADCA or DPT (Comparative Examples 8 to 9), discoloration of the paint due to generation of ammonia was observed.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a gas collecting device.

[Explanation of symbols]

 A decomposition flask B cock C burette D level E thermometer F thermometer G silicone oil bath

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[Procedure amendment]

[Submission date] September 8, 1999 (1999.9.8)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0028

[Correction method] Change

[Correction contents]

[0028]

[Table 2]

Claims (3)

[Claims] 1. A blowing agent composition containing azodicarbonamide, a metal salt of aromatic sulfinic acid and dithiocarbamate. 2. The foam according to claim 1, wherein 0.01 to 1 part by weight of a metal salt of aromatic sulfinic acid and 0.01 to 1 part by weight of a dithiocarbamate are blended with respect to 1 part by weight of azodicarbonamide. Composition. 3. A rubber foam foamed with the foaming agent composition according to claim 1.