WO2010147067A1

WO2010147067A1 - Gas-generating agent

Info

Publication number: WO2010147067A1
Application number: PCT/JP2010/059981
Authority: WO
Inventors: 間山　憲和
Original assignee: 永和化成工業株式会社; 三菱瓦斯化学株式会社
Priority date: 2009-06-19
Filing date: 2010-06-11
Publication date: 2010-12-23
Also published as: KR20120101322A; JPWO2010147067A1; CN102803424B; JP5647606B2; DE112010002570A5; KR101768431B1; CN102803424A

Abstract

A gas-generating agent obtained by combining (A) a nitrogen-containing compound (such as compounds containing a urea bond such as urea and hydrazodicarbonamide) that produces ammonia gas when heated, (B) a nitrite, and (C) hydrotalcite is mixed with a synthetic resin material or a rubber material to obtain a foaming composition, which is then heated and shaped into a foamed body. Thus, nitrogen gas can be generated while suppressing the generation of ammonia or nitrous acid gas, thereby making it possible to obtain a foamed body having uniform, fine gas bubbles and a high degree of whiteness and a high scaling ratio.

Description

Gas generant

The present invention relates to a gas generating agent used for producing a foamed material such as a thermoplastic resin or rubber.

In the production of foams such as thermoplastic resins and rubbers, chemical foaming agents such as azodicarbonamide (ADCA) and foaming aids such as urea are used to adjust the decomposition temperature. In addition, azodicarbonamide is known to generate cyanuric acid, biurea (hydrazodicarbonamide), urea, and the like as decomposition residues during thermal decomposition. Furthermore, it is known that when the heating temperature is 220 ° C. or higher, a part of biurea is decomposed to generate ammonia (see Non-Patent Documents 1 to 3).
Urea compounds produce ammonia by heating, but ammonia gas does not contribute to the expansion ratio. To produce a high-magnification foam, it is necessary to increase the amount of foaming agent added, and ammonia is generated. Therefore, odor countermeasures are required at the foam manufacturing site.

A method of adding molybdenum and a molybdate compound to the foaming agent in order to increase the amount of gas generated by the chemical foaming agent (see Patent Document 1), or a method of supporting a fatty acid alkaline earth metal salt and a quaternary ammonium salt (Patent Document 2) However, these methods cannot make biurea (hydrazodicarbonamide) or ammonia produced during thermal decomposition into nitrogen gas, and it is difficult to suppress odor. Further, Patent Document 3 discloses a method for decomposing and removing organic nitrogen by adding nitrite to water containing organic nitrogen, which is a decomposition treatment of organic nitrogen in an aqueous solution. It cannot be applied to the body manufacturing field.

Japanese Patent Laid-Open No. 2001-139928 JP 2000-336337 A JP-A-9-122690

The purpose of the present invention is to suppress the generation of ammonia and nitrous acid gas and produce nitrogen gas when producing foams such as resin materials and rubber using a compound that generates ammonia gas by heating. An object of the present invention is to provide a gas generating agent capable of obtaining a foam having uniform and fine bubbles and high magnification and high whiteness.

As a result of intensive studies on the above problems, the present inventors have found that the above problems can be solved by using nitrite and hydrotalcite.

That is, this invention relates to the gas generating agent shown below.
(1) A gas generating agent used for the production of a foam, which comprises (A) a nitrogen-containing compound that generates ammonia gas by thermal decomposition, (B) nitrite, and (C) hydrotalcite. Gas generating agent.

(2) The gas generating agent according to (1), wherein the nitrogen-containing compound (A) is a compound having a urea bond.
(3) The total amount of the nitrogen-containing compound (A), nitrite (B) and hydrotalcite (C) is 0.5 to 95% by weight of the nitrogen-containing compound (A) and 0% of nitrite (B). The gas generating agent according to (1) or (2), characterized by containing 5 to 60% by weight and 1 to 40% by weight of hydrotalcite (C).
(4) The gas generating agent according to any one of (1) to (3), wherein the nitrite (B) is at least one selected from the group consisting of sodium nitrite, potassium nitrite and barium nitrite.

(5) The gas generating agent according to any one of (1) to (4), wherein the hydrotalcite (C) is represented by the following general formula (1).

[Chemical 1]
[M ²⁺ _1-x M ³⁺ _x (OH) ₂ ] ^{x +} [A ⁿ⁻ _{x / n} · mH ₂ O] ^x− (1)

( ^Wherein M ²⁺ is a divalent metal ion of a metal selected from the group consisting of Mg, Mn, Fe and Zn, and M ³⁺ is a trivalent metal ion of a metal selected from the group consisting of Al, Fe and Cr , A ⁿ⁻ is an n-valent anion of a group selected from the group consisting of OH, F, Cl, Br, NO ₃ , CO ₃ and SO ₄ , x is in the range of 0 <x ≦ 0.33, n Is an integer and m is 0 or more.)

(6) The gas generating agent according to (5), wherein M ²⁺ in the general formula (1) is Mg ²⁺ and M ³⁺ is Al ³⁺ .
(7) A foaming composition comprising the gas generating agent according to any one of (1) to (6) in a foamed material.
(8) The foaming composition according to (7), wherein the foamed material is a synthetic resin material or a rubber material.
(9) A method for producing a foam, comprising a step of heating the foaming composition according to (7) or (8).

According to the present invention, it is possible to suppress generation of ammonia and nitrous acid gas and generate nitrogen gas in a foam molding temperature range of a synthetic resin material or a rubber material, and generate uniform and fine bubbles at a high magnification. A foam with high whiteness can be obtained. In addition, urea compounds that are usually used as foaming aids such as urea can be used as foaming agents for synthetic resin materials and rubber materials, and when used as foaming aids for chemical foaming agents, While maintaining the function of adjusting the decomposition temperature of the chemical foaming agent, in addition to the generation of gas of the chemical foaming agent, the amount of gas generated can be increased by generating nitrogen gas from the foaming aid. As a result, when manufacturing a foam of thermoplastic resin or rubber, it is possible to manufacture a high-magnification foam without increasing the amount of chemical foaming agent, and at the same time, ammonia can be suppressed, so ammonia at the production site Odor control is unnecessary, which is extremely advantageous industrially.

The reason why high magnification can be achieved without requiring countermeasures for odor in the present invention is that ammonia generated by thermal decomposition of a nitrogen-containing compound is reacted with nitrous acid and changed to nitrogen gas as a foaming gas. It is considered that the use of hydrotalcite at this time increases the reactivity of nitrous acid with ammonia to suppress the generation of nitrous acid gas. In addition, the whiteness is improved by the method of using nitrous acid and hydrotalcite of the present invention in combination with a foaming agent that becomes orange-yellow before pyrolysis and becomes white after decomposition (thermal decomposition) like azodicarbonamide. It is considered that the problem of the residual color occurs when the color is insufficient) because the thermal decomposition is accelerated and the residual color disappears.

The gas generating agent of the present invention is characterized by containing a nitrogen-containing compound (A), a nitrite (B), and a hydrotalcite (C).
The nitrogen-containing compound (A) of the present invention generates ammonia gas by thermal decomposition. Here, ammonia gas is generated by thermal decomposition. Even if the main component of the gas generated by thermal decomposition is ammonia gas, the main component of the gas generated by thermal decomposition is ammonia such as nitrogen gas. It may be a gas other than a gas, and a small amount of ammonia gas may be generated as a by-product in addition to the gas.

Examples of the nitrogen-containing compound (A), urea, hydrazodicarbonamide (hereinafter sometimes referred to as HDCA), biuret, urea bonds (e.g. -NHCONH ₂ such urazol, -NRCONH _2, -NHCONHR, -NRCONHR like; Where R is an organic group), azodicarbonamide (hereinafter sometimes referred to as ADCA), guanidines, 4,4′-oxybis (benzenesulfonylhydrazide) (hereinafter sometimes referred to as OBSH) N, N′-dinitrosopentamethylenetetramine (hereinafter sometimes referred to as DNPT), p-toluenesulfonyl hydrazide (hereinafter sometimes referred to as TSH), 2,2′-azoisobutyronitrile (hereinafter referred to as TSH) , Sometimes referred to as AIBN).

In the present invention, one of these may be used alone, or two or more may be used in combination. Among these, compounds having a urea bond are preferable, and urea and HDCA can be suitably used. As urea, commercially available fine powder urea or fine powder urea whose hygroscopicity is improved by a surface treatment agent such as fatty acid, fatty acid metal salt, fatty acid ester, silane coupling agent, or the like can also be used.

Here, “thermal decomposition” in the nitrogen-containing compound (A) of the present invention means heating when kneading the foam production raw material containing the nitrogen-containing compound (A), and heating when foaming the kneaded product ( For example, when a press mold is used for foaming, thermal decomposition by heating in the press mold) can be exemplified. For example, the heating temperature during the production of the foam is about 130 to 250 ° C.

Examples of the nitrite (B) used in the present invention include sodium nitrite, potassium nitrite, calcium nitrite and the like, and one kind selected from these may be used alone or in combination of two or more kinds. it can. These nitrites are preferably finely divided powder.

The hydrotalcite (C) used in the present invention is a crystalline composite metal hydroxide, and is preferably a hydrotalcite represented by the following general formula (1).

[Chemical 2]
[M ²⁺ _1-x M ³⁺ _x (OH) ₂ ] ^{x +} [A ⁿ⁻ _{x / n} · mH ₂ O] ^x− (1)

In the general formula (1), M ²⁺ is a divalent metal ion of a metal selected from the group consisting of Mg, Mn, Fe, and Zn, and M ³⁺ is a metal selected from the group consisting of Al, Fe, and Cr. Trivalent metal ion, A ⁿ⁻ is an n-valent anion of a group selected from the group consisting of OH, F, Cl, Br, NO ₃ , CO ₃ and SO ₄ , x is in the range of 0 <x ≦ 0.33 Where n is an integer and m is 0 or greater.

Here, m is preferably 0, but it varies depending on the dry state and storage state of hydrotalcite, and m is not particularly limited as long as the effect of the present invention is not impaired. n is the valence of the anion, preferably 1 or 2, and more preferably 2.

Among these, hydrotalcite in which M ²⁺ is Mg ²⁺ and M ³⁺ is Al ³⁺ is preferable, and the molar ratio of Al: Mg is preferably 2: 5 to 2:10 from the viewpoint of availability. For example, when the molar ratio of Al: Mg is 2: 5, the molar fraction x of Al (x = Al / (Mg + Al)) is 0.29, and the molar ratio of Al to Mg is 2:10. In this case, the molar fraction x of Al is 0.17.

The hydrotalcite of the present invention has an action of improving the reactivity of nitrite. By adding hydrotalcite, it promotes the decomposition of ammonia generated when the nitrogen-containing compound (A) is thermally decomposed, and improves the reactivity of nitrite, thereby suppressing the generation of nitrous acid gas, nitrogen gas It is possible to improve the foaming property. The particle diameter of the hydrotalcite of the present invention is not particularly limited, but in order to effectively act on the reaction between the nitrogen-containing compound (A) and nitrite, the dispersibility in the gas generant is increased. It is preferable to use finely divided hydrotalcite having a maximum particle size of 80 μm or less.

The gas generating agent of the present invention contains a nitrogen-containing compound (A), nitrite (B), and hydrotalcite (C) that generate gas by thermal decomposition and generate ammonia gas.
About the ratio of each component in the gas generating agent of this invention, for example, the compounding quantity with respect to the nitrogen-containing compound (A) of the said nitrite (B) and hydrotalcite (C) depends on the amount of generated ammonia gas, and is generated. Since the amount of ammonia gas to be used varies greatly depending on the type of nitrogen-containing compound (A) used, it cannot be generally limited.

However, when the total of the nitrogen-containing compound (A), nitrite (B) and hydrotalcite (C) is 100% by weight, the nitrogen-containing compound (A) is preferably 0.5 to 95% by weight. is there.
The blending amount of nitrite (B) is varied depending on the amount of ammonia gas generated, but is preferably 0.5 to 60% by weight. The blending amount of hydrotalcite (C) is also changed according to the amount of ammonia gas generated, but is preferably 1 to 40% by weight.
When there is too little nitrogen-containing compound (A), nitrous acid gas may leak. If there is too little nitrite (B), ammonia gas may leak.

In addition, the constituents other than (A), (B) and (C) in the gas generating agent of the present invention are not limited as long as the effects of the present invention are not impaired, and the blending amount thereof is also limited. Not. Specific examples of components other than (A), (B) and (C) include fatty acids such as stearic acid or salts of fatty acids such as calcium stearate.

The gas generating agent of the present invention can be used for producing foams such as various synthetic resin materials and rubber materials to obtain a suitable foam. A gas generating agent can be blended and used as a composite gas generating agent.

Examples of the thermal decomposition type chemical foaming agent that can be used in the composite gas generating agent include general chemical foaming agents that generate nitrogen gas or carbon dioxide gas by thermal decomposition. For example, azodicarbonamide, 4,4 ′ -Chemical foaming agents such as oxybis (benzenesulfonylhydrazide), N, N'-dinitrosopentamethylenetetramine, 5-phenyl-1,2,3,4-tetrazole, and organic acids such as monosodium citrate and sodium tartrate Examples thereof include organic chemical foaming agents for metal salts and inorganic chemical foaming agents such as sodium hydrogen carbonate. You may use these individually by 1 type or in combination of 2 or more types.

The mixing ratio of the gas generating agent of the present invention and the pyrolytic chemical foaming agent in the composite gas generating agent is not particularly limited, but preferably [the gas generating agent of the present invention]: [thermal decomposing chemical foaming agent] = 5 to 95. : 95 to 5 (weight ratio).

Further, when the gas generating agent of the present invention is used in combination with a pyrolytic chemical foaming agent, the pyrolytic chemical foaming agent first generates a decomposing foaming gas as the heating temperature rises, and then the gas generating of the present invention A two-stage decomposition foaming agent can be obtained by selecting and combining gas generating agents having different gas generation temperatures such that the agent generates nitrogen gas (or vice versa). By using such a two-stage decomposition type foaming agent, it becomes possible to produce a characteristic foam having a high foaming ratio.

The method for producing the gas generating agent of the present invention is not particularly limited, and a general mixing method can be used. For example, the nitrogen-containing compound (A), nitrite (B), and hydrotalcite (C) are uniformly applied using a high-speed mixer, ribbon blender, corn blender, etc. under conditions of a temperature of 60 ° C. or less and a time of about 5 minutes. What is necessary is just to mix so that it may disperse | distribute.

The method for producing the composite gas generating agent of the present invention is not particularly limited, and a general mixing method can be used. When producing the gas generating agent of the present invention, the pyrolytic chemical foaming agent may be mixed together, or after producing the gas generating agent of the present invention, the pyrolytic chemical foaming agent may be mixed. . The composite gas generating agent may be mixed using, for example, a high-speed mixer, ribbon blender, cone blender, or the like so as to be uniformly dispersed under conditions of a temperature of 60 ° C. or less and a time of about 5 minutes.

The gas generating agent or composite gas generating agent of the present invention can be suitably used for foam molding of synthetic resin materials or rubber materials. The gas generating agent or composite gas generating agent of the present invention can suppress generation of ammonia and nitrous acid gas and generate nitrogen gas at a foam molding temperature (for example, about 130 to 250 ° C.) of a synthetic resin material or rubber material. Thus, a foam having uniform and fine bubbles and high magnification and high whiteness can be obtained.

The foaming composition of the present invention is obtained by blending the above-described gas generating agent of the present invention into a material to be foamed. Examples of the foamed material include synthetic resin materials and rubber materials.
Examples of the synthetic resin material of the present invention include a vinyl chloride resin, a vinyl chloride copolymer resin, polyethylene, polypropylene, a polyolefin copolymer resin exemplified by an ethylene-propylene copolymer, a polystyrene resin, and an acrylonitrile-butadiene-styrene copolymer. (ABS resin) and the like are exemplified, but not limited thereto.

As a method for producing a foam by blending the gas generating agent or composite gas generating agent of the present invention with a synthetic resin material, a general method for producing a foam can be used. For example, the foaming composition (unfoamed resin composition) can be prepared by kneading the synthetic resin material, the crosslinking agent, and the gas generating agent or composite gas generating agent of the present invention with a heated kneading roll. . The kneading temperature is preferably 90 to 130 ° C.

The unfoamed resin composition thus obtained is filled in a mold and pressed with a press to obtain a foam of a synthetic resin material. There are no particular restrictions on the mold thickness, pressure conditions, and the like, and conventionally known foam molding methods can be appropriately employed depending on the type and application of the synthetic resin. For example, a foam of a resin composition can be obtained by filling 100% in a mold having a thickness of 5 to 30 mm and pressurizing with a press machine at 145 to 170 ° C. and 150 kg / cm ² for 5 to 60 minutes.

The blending ratio of each component in the foaming composition is not particularly limited, but the crosslinking agent is preferably 0.1 to 10 parts by weight, more preferably 0.5 to 1.5 parts by weight with respect to 100 parts by weight of the synthetic resin material. Partly formulated. If the blending ratio of the cross-linking agent is too small, the cross-linking may become under, resulting in insufficient foaming due to outgassing, and if too large, the cross-linking may be over and the foam may be cracked or roughened.

The amount of the gas generating agent of the present invention can be appropriately selected according to the target foaming ratio and is not particularly limited, but is preferably 1 to 7 parts by weight per 100 parts by weight of the synthetic resin material. .

When the composite gas generating agent containing the gas generating agent of the present invention is used, the amount of the composite gas generating agent used can be appropriately selected according to the target foaming ratio and is not particularly limited. 1 to 7 parts by weight is blended with 100 parts by weight of the resin material.

Since the nitrogen-containing compound (A) contained in the gas generating agent of the present invention is the one conventionally used as a foaming aid for a chemical foaming agent, composite gas generation containing the gas generating agent of the present invention is used. The agent also has a function of adjusting the decomposition temperature for the chemical foaming agent as the foaming aid.
On the other hand, urea-based foaming aids conventionally did not contribute to foaming even when ammonia was generated by thermal decomposition, but the gas generating agent of the present invention generates nitrogen gas by combining nitrite and hydrotalcite. Can contribute to foaming. Therefore, in addition to the foaming gas derived from the chemical foaming agent, the nitrogen gas derived from the foaming aid can also be used as the foaming gas, so that the generated gas can be increased with the same amount of chemical foaming agent used. In other words, a foam having the same expansion ratio can be produced with a smaller amount of chemical foaming agent than in the past.

As described above, when the gas generating agent of the present invention is combined with the conventional chemical foaming agent, the effect of improving the expansion ratio can be exhibited while exhibiting the function of adjusting the decomposition temperature of the chemical foaming agent.
The ratio of the gas generating agent of the present invention in the composite gas generating agent is not particularly limited, and can be appropriately selected according to the target expansion ratio. For example, it can be used according to the ratio of the foaming aid to the chemical foaming agent in the case of combining a conventional chemical foaming agent and a foaming aid.

Examples of the crosslinking agent include dicumyl peroxide, di-t-butyl peroxide, 2,5-dimethyl-2,5-di- (t-butylperoxy) hexane, 2,5-dimethyl-2,5-di -(T-butylperoxy) hexyne-3,1,3-bis (t-butylperoxyisopropyl) benzene, 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane, n-butyl- 4,4-bis (t-butylperoxy) valerate, benzoyl peroxide, p-chlorobenzoyl peroxide, 2,4-dichlorobenzoyl peroxide, t-butylperoxybenzoate, t-butylperbenzoate, t-butylperoxyisopropyl carbonate, diacetyl Peroxide, lauroyl peroxide, t-butyl Or the like can be used torque mill peroxide.

Examples of the rubber material of the present invention include natural rubber (NR), polyisoprene rubber, styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber, chloroprene rubber, ethylene-propylene rubber, ethylene-propylene-diene rubber, butadiene rubber and the like. However, it is not limited to these.

As a method for preparing a foaming composition by blending the gas generating agent or composite gas generating agent of the present invention into a rubber material, and thereby manufacturing a foam, general manufacturing conditions for the foam can be used. . For example, a rubber material, a vulcanizing agent, a filler, a vulcanization accelerator, and the gas generating agent or composite gas generating agent of the present invention are uniformly dispersed with a kneading roll to obtain a foaming composition. The obtained foaming composition is put into an extruder heated to about 70 to 90 ° C. to prepare an unvulcanized molded body. The resulting unvulcanized molded body is heated in an oven heated to about 60 to 220 ° C. for about 5 to 15 minutes to vulcanize and foam to obtain a foam of rubber material.

The blending ratio of each component in the foaming composition is not particularly limited, but the vulcanizing agent is preferably blended in an amount of 0.1 to 10 parts by weight with respect to 100 parts by weight of the rubber material. The filler is preferably blended in an amount of 10 to 150 parts by weight per 100 parts by weight of the rubber material. The vulcanization accelerator is preferably blended in an amount of 0.1 to 20 parts by weight per 100 parts by weight of the rubber material.

The amount of the gas generating agent of the present invention can be appropriately selected according to the target foaming ratio and is not particularly limited, but is preferably 1 to 20 parts by weight per 100 parts by weight of the rubber material. When the composite gas generating agent containing the gas generating agent of the present invention is used, the usage amount of the composite gas generating agent can be appropriately selected according to the target foaming ratio and is not particularly limited, but preferably rubber. 1 to 20 parts by weight per 100 parts by weight of the material.

Specific examples of the vulcanizing agent used in the present invention include sulfur.
Specific examples of the filler used in the present invention include heavy and light calcium carbonate.
Specific examples of the vulcanization accelerator used in the present invention include DM (dibenzylthiazol disulfide).

The gas generating agent of the present invention is economical because it is possible to produce a foam having the same magnification with an addition amount smaller than that of a conventional product. At the same time, problems such as poor adhesion and fogging of resin foam caused by urea compounds by using nitrogen gas as a by-product such as ammonia odor generated from chemical blowing agents and urea compounds, urea compounds and biurea (hydrazodicarbonamide) Can also be improved.

Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to these examples. Unless specifically limited in the following examples and comparative examples, the amount of gas generated, the amount of nitrous acid gas generated, the amount of ammonia generated, the specific gravity of the foam, and the bubble state of the foam were evaluated by the following methods.

<Measurement of generated gas amount>
Take 1 g of gas generant or composite gas generant in a test tube, add 10 ml of liquid paraffin as a heating medium, and then connect the test tube to the sodium hydroxide aqueous solution absorption bottle, boric acid aqueous solution absorption bottle, and gas burette in this order. The tube was immersed in a 60 ° C. oil bath. Thereafter, the oil bath was heated to 220 ° C. at a temperature rising rate of 2 ° C./min. All the gas generated during heating was collected with a gas burette, and the amount of generated gas was determined.

<Measurement of nitrous acid generation amount>
The gas generated during pyrolysis was absorbed in an absorption bottle containing 400 ml of 1N aqueous sodium hydroxide solution, and the amount of nitrous acid gas generated in the absorbing solution was measured according to JIS-K0102 (naphthylethylenediamine absorptiometry).

<Measurement of ammonia generation amount>
The gas passing through the absorption bottle containing the aqueous sodium hydroxide solution is absorbed by the absorption bottle containing 400 ml of 0.5N boric acid aqueous solution, and then absorbed in the absorption liquid according to JIS-K0102 (Indophenol blue absorptiometry). The amount of ammonia generated was measured.

<Specific gravity of foam>
The specific gravity of the foam of the resin composition and the rubber composition was determined by an electronic hydrometer (manufactured by Alpha Mirage, product name MD-200S).

<Evaluation of bubble state of foam>
SEM (manufactured by Keyence Corporation, VE-7800) was used for evaluation of the bubble state of the resin composition and the rubber composition. The foamed molded product was sliced parallel to the thickness direction, the slice cross section was observed with SEM, and the bubble state and bubble diameter were observed.

<Water content survey of hydrotalcite>
Measuring instrument: Karl Fischer moisture meter MKC-210 manufactured by Kyoto Electronics

<Example 1>
60 g (1 mole) of urea (manufactured by Mitsui Chemicals, Inc., industrial mole), 69 g of sodium nitrite (1 mole) (manufactured by Nissan Chemical Industries, sodium nitrite (wet)), hydrotalcite ([Mg ²⁺ _0.83 Al ³⁺ _0.17 (OH) ₂ ] ^0.17+ [(CO ₃ ) ^{2 −} _{0.17 / 2} · 0.33H ₂ O] ^0.17− , Al: Mg molar ratio = 2: 10) 6 g After mixing for 5 minutes at room temperature using a polyethylene bag, it was pulverized to 150 mesh pass (using JIS8801 sieve) with a ball mill to obtain a gas generating agent.
The amount of generated gas was measured using 1 g of the obtained gas generating agent. When the amount of generated gas was measured, gas generation was observed from 120 ° C., gas was rapidly generated at 155 ° C., and rapid gas generation was completed at 158 ° C., but slow gas generation was observed up to 180 ° C., and thereafter 220 ° C. Until now, no gas generation was observed. Table 1 shows the measurement results of the generated gas amount, the nitrous acid gas generated amount, and the ammonia generated amount.

Next, 100 parts by weight of ethylene-vinyl acetate copolymer (EVA) (trade name “Ultrasen 630” manufactured by Tosoh Corporation) is mixed with a mixing roll heated to 90 to 100 ° C., and then the gas generating agent is mixed. 5 parts by weight was added and kneaded for 5 minutes, then 0.8 part by weight of dicumyl peroxide (DCP) was added and kneaded for 3 minutes, and the kneaded product was taken out from the mixing roll. The kneaded product was charged so that the inner volume of the mold (200 mm × 200 mm × 10 mm) of the press apparatus heated to 160 ° C. was filled to 100%, and pressurized at a press pressure of 150 kg / cm ² for 10 minutes. After 10 minutes, the press pressure was released to normal pressure all at once, and a foam was obtained. Table 2 shows the blending amount of the obtained foam and the evaluation results.

<Comparative Example 1>
Production of foam by measuring the amount of generated gas, amount of nitrous acid gas, and amount of ammonia generated in the same manner as in Example 1 except that hydrotalcite was replaced with zeolite deodorant (Zeolam A-4, manufactured by Tosoh Corporation). Went. Table 1 shows the blending amount and evaluation result of the gas generating agent, and Table 2 shows the blending amount and evaluation result of the foam. The obtained foam was colored light yellow and the degree of crosslinking was low, so that the foam adhered to the mold and could not be taken out.

<Example 2>
Urea (manufactured by Mitsui Chemicals, industrial urea) 60 g (1 mol), sodium nitrite (manufactured by Nissan Chemical Industries, sodium nitrite (wet)) 69 g (1 mol), hydrotalcite ([Mg ²⁺ _0.71 Al ³⁺ _0.29 (OH) ₂ ] ^0.29+ [(CO ₃ ) ² −0.29 _{/ 2} · 0.57H ₂ O] ^0.29− , Al: Mg molar ratio = 2: 5) 18 g, 6 g of calcium stearate (manufactured by NOF Corporation, calcium stearate) was mixed at room temperature for 5 minutes using a polyethylene bag, and then pulverized to 150 mesh pass with a ball mill to obtain a gas generating agent.
Using 1 g of the gas generant, the amount of gas generated, the amount of nitrous acid gas generated, and the amount of ammonia generated were measured in the same manner as in Example 1 to produce a foam. Table 1 shows the blending amount and evaluation result of the gas generating agent, and Table 2 shows the blending amount and evaluation result of the foam.

<Comparative Example 2>
Except that hydrotalcite was removed from the formulation of Example 2, the amount of gas generated, the amount of nitrous acid generated, and the amount of ammonia generated were measured in the same manner as in Example 2 to produce a foam. Table 1 shows the blending amount and evaluation result of the gas generating agent, and Table 2 shows the blending amount and evaluation result of the foam. The obtained foam was pale yellow and adhered to the mold and could not be taken out.

<Example 3>
Urea (manufactured by Mitsui Chemicals, industrial urea) 60 g (1 mole), sodium nitrite (manufactured by Nissan Chemical Industries, sodium nitrite (wet)) 69 g (1 mole), hydrotalcite ([Mg ²⁺ _0.83 Al ³⁺ _0.17 (OH) ₂ ] ^0.17+ [(CO ₃ ) ^{2 −} _{0.17 / 2} · 0.33H ₂ O] ^0.17− , Al / Mg molar ratio = 2: 10) 18 g After mixing for 5 minutes at room temperature using a polyethylene bag, it was pulverized to 150 mesh pass with a ball mill. 200 g of chemical foaming agent azodicarbonamide (ADCA) (trade name “VINYHALL AC # 3” manufactured by Eiwa Kasei Kogyo Co., Ltd.), 53 g of zinc oxide (manufactured by Sakai Chemical Co., Ltd., 2 types of zinc oxide), polyethylene, A gas generating agent was obtained by mixing at room temperature for 5 minutes using a bag. Using 1 g of the resulting gas generant, the amount of gas generated, the amount of nitrous acid gas generated, and the amount of ammonia generated were measured in the same manner as in Example 1. Table 1 shows the blending amount of the gas generating agent and the evaluation results.

Next, in a kneader heated to 110 to 120 ° C., 100 parts by weight of low density polyethylene (trade name “NOVATEC PE YF30” manufactured by Nippon Polyethylene Co., Ltd.), 10 parts by weight of the gas generating agent, dicumyl peroxide (DCP) 1 part by weight was added and kneaded. The kneaded material was charged so that the inner volume of the mold (200 mm × 200 mm × 10 mm) of the press apparatus heated to 155 ° C. was 100% filled, and pressurized at a press pressure of 150 kg / cm ² . After 15 minutes, the press pressure was released to normal pressure all at once, and a foam was obtained. The amount of foam blended and the evaluation results are shown in Table 2.

<Comparative Example 3>
The chemical foaming agent azodicarbonamide (ADCA) (trade name “Binihol AC # 3”, Eiwa Kasei Co., Ltd.) was used in the same manner as in Example 3 except that the hydrotalcite was replaced with aluminum silicate (Wako Pure Chemical Industries, Ltd., aluminum silicate). Industrial Co., Ltd.) and zinc oxide (manufactured by Sakai Chemical Co., Ltd., 2 types of zinc oxide) were mixed to obtain a gas generating agent. In the same manner as in Example 1, the amount of gas generated, the amount of nitrous acid gas generated, and the amount of ammonia generated were measured, and then a foam was produced in the same manner as in Example 3. Table 1 shows the blending amount and evaluation result of the gas generating agent, and Table 2 shows the blending amount and evaluation result of the foam. The obtained foam was colored light yellow, and the bubbles inside the foam were also non-uniform.

<Example 4>
Urea (manufactured by Mitsui Chemicals, industrial urea) 60 g (1 mole), sodium nitrite (manufactured by Nissan Chemical Industries, sodium nitrite (wet)) 69 g (1 mole), hydrotalcite ([Mg ²⁺ _0.83 Al ³⁺ _0.17 (OH) ₂ ] ^0.17+ [(CO ₃ ) ² −0.17 _{/ 2} · 0.33H ₂ O] ^0.17− , Al: Mg molar ratio = 2: 10) 12 g, 6 g of magnesium stearate (manufactured by Sakai Chemical Co., Ltd., SM-1000) was mixed at room temperature for 5 minutes using a polyethylene bag, and then ground to 150 mesh pass with a ball mill. 62.6 g of azodicarbonamide (ADCA) (trade name “VINYHALL AC # 3” manufactured by Eiwa Kasei Kogyo Co., Ltd.), chemical foaming agent N, N′-dinitrosopentamethylenetetramine (DNPT) (trade name) “Cellular D” (manufactured by Eiwa Chemical Industry Co., Ltd.) 93.8 g and zinc oxide (manufactured by Sakai Chemical Co., Ltd., 2 types of zinc oxide) 9.4 g were mixed in a polyethylene bag for 5 minutes at room temperature to obtain a gas generating agent. It was. Using the obtained gas generating agent, the amount of generated gas, the amount of generated nitrous acid gas, and the amount of generated ammonia were measured in the same manner as in Example 1. Table 1 shows the blending amount of each agent and the evaluation results.

Next, 60 parts by weight of NR (RSS # 1) and 40 parts by weight of SBR (1502) are kneaded with a kneader, and 50 parts by weight of calcium carbonate (Bihoku Powder Chemical Co., Ltd., Whiten SB) and white carbon (manufactured by DSL Japan). Carplex # 80) 20 parts by weight, titanium dioxide (manufactured by Wako Pure Chemical Industries, titanium oxide) 10 parts by weight, zinc oxide (manufactured by Sakai Chemical Co., Ltd., 2 types of zinc oxide), 5 parts by weight, stearic acid (manufactured by Kao Corporation, 3 parts by weight of Lunac S-20) and 5 parts by weight of naphthenic oil (Sansen 410, manufactured by Nippon San Oil Co., Ltd.) were added and further kneaded and taken out. This kneaded product is wound around a mixing roll, 2.5 parts of sulfur (manufactured by Tsurumi Chemical Co., Ltd., fine powdered sulfur) and 1 part of vulcanization accelerator DM are added and kneaded for 3 minutes as a vulcanizing agent, and then a foaming agent mixture 15 Part was added and kneaded for 3 minutes.
The kneaded material was charged so that the inner volume of the mold (124 mm × 124 mm × 11 mm) of the press apparatus heated to 150 ° C. was filled to 100%, and pressurized at a press pressure of 150 kg / cm ² . After 15 minutes, the press pressure was released to normal pressure all at once, and a foam was obtained. The amount of foam blended and the evaluation results are shown in Table 2.

<Comparative example 4>
Except that hydrotalcite was removed from the formulation of Example 4, the same operations as in Example 4 were performed, and the amount of generated gas, the amount of nitrous acid gas generated, and the amount of ammonia generated were measured to produce a foam. Table 1 shows the blending amount and evaluation result of the gas generating agent, and Table 2 shows the blending amount and evaluation result of the foam. The bubbles inside the foam were not uniform.

<Example 5>
118 g (1 mol) of biurea (hydrazodicarbonamide, manufactured by Eiwa Kasei Kogyo Co., Ltd., FE-823), 42.5 g (0.5 mol) of potassium nitrite (manufactured by Wako Pure Chemical Industries, Ltd., Wako special grade potassium nitrite), hydro ^Talsite ([Mg ²⁺ _0.83 Al ³⁺ _0.17 (OH) ₂ ] ^0.17+ [(CO3) ^{2 −} _{0.17 / 2} · 0.33H ₂ O] ^0.17− , Al: Mg mole A ratio of 2:10) 12 g was mixed at room temperature for 5 minutes using a polyethylene bag, and then pulverized to 150 mesh pass with a ball mill to obtain a gas generating agent.
Measurement of generated gas amount, nitrous acid gas generated amount, and ammonia generated amount in the same manner as in Example 1 except that 1 g of the obtained gas generating agent was used and the oil bath temperature 220 ° C. at the time of measuring the generated gas amount was changed to 250 ° C. Went. Table 1 shows the blending amount of the gas generating agent and the evaluation results.

Next, 1 part by weight of liquid paraffin and 3 parts by weight of the gas generating agent obtained above were added to and mixed with 100 parts by weight of polypropylene (trade name “NOVATEC PP MA3” manufactured by Nippon Polypro Co., Ltd.). The mixture was put into an extruder (Toyo Seiki Laboplast Mill 50C150, Extrusion Mechanical D2025), set temperature C1; 200 ° C, C2; 240 ° C, C3; 200 ° C, die: 180 ° C, screw rotation speed 80 rpm Extruded to obtain a foam sheet. The amount of foam blended and the evaluation results are shown in Table 2.

<Comparative Example 5>
Except for removing hydrotalcite from the formulation of Example 5, the amount of generated gas, the amount of nitrous acid generated, and the amount of ammonia generated were measured in the same manner as in Example 5 to produce a foam. Table 1 shows the blending amount and evaluation result of the gas generating agent, and Table 2 shows the blending amount and evaluation result of the foam. The obtained foam was colored pale yellow and almost no bubbles were observed.

As shown in Table 1, in Examples 1 to 5, the amount of generated gas was improved, the detected amount of nitrous acid was decreased, and ammonia was not detected in all gas generating agents. Therefore, in Examples 1 to 5, it was confirmed that the nitrite reactivity was improved by hydrotalcite, nitrous acid gas was reduced, ammonia was further decomposed, and the amount of nitrogen gas generated during foaming was increased. It was done.

As shown in Table 2, Examples 1 to 5 are excellent in whiteness of the foam, and the bubbles inside the foam are fine and uniform bubbles. As can be seen from the specific gravity of the foam, the expansion ratio is as follows. It was confirmed to improve.

According to the present invention, when producing a foam of thermoplastic resin or rubber, it is possible to produce a high-magnification foam without increasing the amount of the chemical foaming agent, and at the same time, it is possible to suppress ammonia, and thus the production site This eliminates the need for ammonia odor countermeasures, and is extremely advantageous industrially.

Claims

A gas generating agent used for producing a foam, which comprises (A) a nitrogen-containing compound that generates ammonia gas by thermal decomposition, (B) nitrite, and (C) hydrotalcite Generating agent.
The gas generating agent according to claim 1, wherein the nitrogen-containing compound (A) is a compound having a urea bond.
The total amount of the nitrogen-containing compound (A), nitrite (B), and hydrotalcite (C) is 0.5 to 95% by weight of the nitrogen-containing compound (A) and 0.5 to 95% of the nitrite (B). The gas generating agent according to claim 1 or 2, comprising 60% by weight and 1 to 40% by weight of hydrotalcite (C).
The gas generating agent according to any one of claims 1 to 3, wherein the nitrite (B) is at least one selected from the group consisting of sodium nitrite, potassium nitrite and barium nitrite.
The gas generating agent according to any one of claims 1 to 4, wherein the hydrotalcite (C) is represented by the following general formula (1).
[Chemical 1]
[M 2+ 1-x M 3+ x (OH) 2 ] x + [A n− x / n · mH 2 O] x− (1)
( Wherein M 2+ is a divalent metal ion of a metal selected from the group consisting of Mg, Mn, Fe and Zn, and M 3+ is a trivalent metal ion of a metal selected from the group consisting of Al, Fe and Cr , A n− is an n-valent anion of a group selected from the group consisting of OH, F, Cl, Br, NO 3 , CO 3 and SO 4 , x is in the range of 0 <x ≦ 0.33, n Is an integer and m is 0 or more.)
The gas generating agent according to claim 5, wherein M 2+ in the general formula (1) is Mg 2+ and M 3+ is Al 3+ .
A foaming composition comprising the foamed material and the gas generating agent according to any one of claims 1 to 6.
The foaming composition according to claim 7, wherein the foamed material is a synthetic resin material or a rubber material.
The manufacturing method of a foam including the process of heating the foaming composition of Claim 7 or 8.