JPH10140133A - Blowing agent containing azobisamidoxime - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a blowing agent which enables low-temp. foaming, does not emit a bad malodor, and is highly safe by incorporating a specific compd. into the same. SOLUTION: This blowing agent contains an azobisamidoxime represented by the formula [wherein R<1> is a 1-6C alkyl; and R<2> is a 2-6C alkyl provided R<1> and R<2> may combine with each other to form (CH2 )6 ]. An azobisamidoxime is obtd. by reacting an azobisnitrile compd. with hydroxylamine at a temp. in the range of from normal temp. to about the decomposition point (about 90-120 deg.C) of the nitrile compd., pref. about normal temp. by using methanol, ethanol, etc., as the solvent. Pref. 1mol of the nitrile compd. is reacted with about 2-6mol of hydroxylamine; and the reaction product is treated in a usual way to give a product in the form of crystals.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a foaming agent containing azobisamide oxime and a foam obtained by using the same.

[0002]

2. Description of the Related Art Conventionally, azodicarbonamide (ADCA), p, p'-oxybis (benzenesulfonylhydrazide) (OBSH), dinitrosopentamethylenetetramine (DPT), p-toluenesulfonylhydrazide have been used as blowing agents for synthetic resins. (TSH) 2,2′-azobisisobutyronitrile (AIBN) and the like are used. These are substances which decompose by heating to generate gas, and these foaming agents are kneaded in a synthetic resin and heated to obtain a foam. In addition, some synthetic resins are cured by gelation or crosslinking reaction,
A foam is obtained by mixing a foaming agent in advance and heating to cause gelation and foaming, or foaming while performing a crosslinking reaction. These foaming agents are selected and used according to the size of the cell diameter, the expansion ratio, the operating temperature and the like.

[0003]

[0006] Conventionally used blowing agents are properly used depending on the decomposition temperature in order to produce useful foams. That is, the decomposition temperature of ADCA and DPT is 200 to 210 ° C. These are 150-25
It is decomposed by heating at 0 ° C. to generate gas to produce a foam. Therefore, it cannot be used for a resin that deteriorates when heated to this temperature. In addition, when the colorant discolors, the shape is abnormal, or the generated gas escapes due to the melt viscosity being too low, these foaming agents cannot be used. Fifteen
At a temperature of 0 ° C. or lower, the decomposition is remarkably slowed or the decomposition rate is remarkably reduced, so that a satisfactory foam cannot be obtained.

As a foaming agent capable of foaming at a low temperature, OBS
H, TSH and AIBN are used. The decomposition temperature of OBSH is 155 to 160 ° C, and that of TSH is 103 to 107 ° C.
C. and 100 to 102 C. for AIBN. But O
Since both BSH and TSH contain sulfur atoms, they cannot avoid the generation of sulfurous acid gas and offensive odor when decomposed. AIBN contains a cyano group,
When decomposed, several kinds of organic cyanide compounds are generated, and it is necessary to completely remove these by heat treatment from the viewpoint of safety. The generation of offensive odors, besides the possibility of remaining in the foam, gives a worker an uncomfortable feeling in the working environment during the production, and also requires a large amount of cost when providing abatement equipment. The present invention provides a highly safe foaming agent which can be foamed at a low temperature and does not generate a bad odor, and a foam having fine and uniform cells having a smooth surface and no tackiness obtained by using the same. As an issue.

[0005]

The present invention relates to a blowing agent containing an azobisamide oxime represented by the general formula (1).

[0006]

Embedded image [In the formula, R ¹ represents an alkyl group having 1 to 6 carbon atoms. R ² represents an alkyl group having 2 to 6 carbon atoms. Alternatively, R ¹ and R ² are bonded to form a group — (CH ₂ ) ₅ —. ]

Further, the present invention relates to a highly safe foam which is obtained by using the foaming agent of claim 1 and which has no possibility of remaining offensive odor. We can foam at low temperature,
As a result of intensive studies to obtain a foam having high odor and high safety, it was found that a novel azobisamide compound achieves this object.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION In the azobisamide oxime represented by the general formula (1) of the present invention, specific examples of R ¹ include a methyl group, an ethyl group, a propyl group, a butyl group, an isobutyl group, a t-butyl group, Examples include a pentyl group and a hexyl group. Specific examples of R ^2, there can be mentioned an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, t- butyl group, a pentyl group, a hexyl group. R ¹ and R ² are bonded to form-(CH ₂ ) _5-
Groups may be formed.

Among the azobisamide oximes represented by the general formula (1) of the present invention, the following compounds are particularly preferred. A compound wherein R ¹ is a methyl group and R ² is an ethyl group. A compound wherein R ¹ is a methyl group and R ² is an isobutyl group. Compounds in which R ¹ and R ² together with the carbon to which they are attached form a cyclohexyl group. The azobisamide oxime of the present invention is obtained, for example, by reacting an azobisnitrile compound represented by the general formula (2) with hydroxylamine.

[0010]

Embedded image (In the formula, R ¹ and R ² are the same as above.)

The reaction is carried out at room temperature to the decomposition temperature of the azobisnitrile compound represented by the general formula (2) (about 90 to 120).
C.), preferably at about room temperature. When the reaction is performed in a solvent, the solvent preferably has good solubility in both the azobisnitrile compound and hydroxylamine, and specific examples include methanol and ethanol. The azobisnitrile compound can be used by directly adding it to a solvent. Hydroxylamine can be used directly or by dissolving it in water or the like.
It is preferable to use an aqueous solution of about 60% by weight.

As for the ratio of hydroxylamine to the azobisnitrile compound, the latter is used in an amount of 2 to 10 moles, preferably about 2 to 6 moles, per mole of the former. The reaction can be allowed to proceed with stirring, usually from 1 to
Complete in about 10 hours. The reaction product can be separated by a usual method. For example, the reaction product can be separated in a crystalline state by a method such as concentration under reduced pressure followed by filtration.

The obtained crystals may be used as they are after drying, but in order to obtain a foam having finer cells, it is more preferable to grind them by a commonly used method. Known blowing agents, foaming aids, compounding agents, and the like may be added to the blowing agent of the present invention as long as the effects are not impaired. Examples of the foaming agent include inorganic chemical foaming agents such as sodium bicarbonate and ammonium carbonate, organic chemical foaming agents such as azobisisobutyronitrile and p-toluenesulfonylhydrazide, aliphatic hydrocarbons, and chlorinated aliphatic hydrocarbons. ,
Physical blowing agents such as fluorinated aliphatic hydrocarbons, carbon dioxide gas, and nitrogen gas can be used.

Examples of the foaming aid include metal oxides such as zinc oxide, lead oxide and magnesium oxide, metal carbonates such as zinc carbonate and barium carbonate, metal chlorides such as zinc chloride and potassium chloride, and lithium stearate. , Magnesium stearate, aluminum stearate, calcium stearate, barium stearate, zinc stearate, cadmium stearate, lead stearate, dibasic lead stearate, calcium laurate, zinc laurate, zinc 2-ethylhexoate, dibasic Metallic soaps such as basic lead phthalate, inorganic salts such as tribasic lead sulfate, dibasic lead phosphite and basic lead sulfite, organic tin compounds such as dibutyltin dilaurate and dibutyltin dimaleate, dibutyltin dilaurate , Dibutyltin dimaleate, calcium-zinc, burr Beam - PVC composite stabilizer zinc, etc., can be mentioned sulfonic acid metal compounds.

Examples of the compounding agent include a plasticizer, a stabilizer, a vulcanizing agent, a vulcanization accelerator, a cross-linking agent, an anti-scorch agent, an antioxidant, an anti-aging agent, a softener, a tackifier, and an ultraviolet absorber. , Coloring agents, flame retardants, dispersants, antistatic agents, reinforcing materials,
Examples include a curing agent, an adhesive, a fluorescent whitening agent, and a release agent. The blowing agent of the present invention can be produced by mixing the azobisamide oxime and other components as necessary according to a usual method. When mixing
For example, a normal mixer such as a Henschel mixer or a ribbon mixer can be used.

The foaming agent of the present invention can be applied to various materials to be foamed, like the conventional foaming agent. The material to be foamed is not particularly limited, and examples thereof include a synthetic resin, a synthetic rubber, a natural rubber, and a mixture of two or more of these. The synthetic resin is not particularly limited, and known ones can be used.For example, polyvinyl chloride, polyethylene, polypropylene, polymethyl acrylate, polymethyl methacrylate, ethylene-vinyl acetate copolymer, ethylene propylene terpolymer,
Examples include acrylonitrile-butadiene-styrene terpolymer, polystyrene, polyacrylonitrile, polyurethane, and urethane-vinyl chloride copolymer. The synthetic rubber is not particularly limited, but examples thereof include styrene butadiene rubber, nitrile butadiene rubber, chloroprene rubber, isobutylene rubber, isoprene rubber, butadiene rubber, acrylic rubber, chlorinated butyl rubber, and ethylene-propylene-diene terpolymer. it can. The foaming agent of the present invention is particularly effective for foaming thermoplastic polyurethane, synthetic rubber, natural rubber and the like.

In foaming the material to be foamed using the foaming agent of the present invention, any known method conventionally used for producing foams can be employed. That is, the foaming agent of the present invention may be added to and mixed with the material to be foamed, and a foaming component contained in the foaming agent may be decomposed to generate gas.
More specifically, for example, a foaming agent and a material to be foamed are kneaded by a roll, an extruder or the like, the obtained mixture is filled in a mold, and the foamed component is decomposed by pressing and heating with a press. Method (press pressure foam molding method), method of molding a mixture of a foaming agent and a material to be foamed by an extruder (extrusion foam molding method, injection foaming molding method), sheet-like mixture of the foaming agent and the material to be foamed Or into any shape such as paper or release paper, cloth,
After coating on a board or the like, for example, a method of decomposing a foaming agent component by placing it in a heating device such as a hot-air foaming furnace or an infrared heating foaming furnace (normal pressure foaming method) can be mentioned. When producing a foam using the foaming agent of the present invention,
The amount of the foaming agent added to the material to be foamed may be appropriately selected from a wide range according to various conditions such as the material of the material to be foamed and the use of the foam to be obtained.
The amount may be about 0.01 to 50 parts by weight, preferably about 0.1 to 30 parts by weight based on parts by weight.

The temperature at which the foam is produced is preferably at least 50 ° C. lower than the decomposition temperature of the foaming agent, more preferably at least 20 ° C. lower. In addition, foaming can be performed while causing a curing reaction or a crosslinking reaction. Foam obtained by using the foaming agent of the present invention, like the conventional foam,
It can be used as a heat insulating material, an interior material, a sealing material, a cushioning material, and the like in a wide range of fields such as civil engineering construction, agricultural and forestry fisheries, transportation equipment such as automobiles, electric and electronic equipment, and life-related products.

[0019]

The present invention will be described in more detail with reference to the following examples. Example 1 2,2'-azobis (2-methylbutanamide oxime)
To 60 ml of methanol was added 19.2 g of 2,2'-azobis (2-methylbutyronitrile) and the mixture was stirred. 20-30 ° C
Then, 33.0 g of a 50% aqueous solution of hydroxylamine was added dropwise over 5 minutes at a temperature of 20 ° C., followed by stirring at 20 to 30 ° C. for 6 hours to cause a reaction. After the reaction, the mixture was concentrated under reduced pressure at 25 ° C. 60 ml of water
The mixture was stirred, filtered, and dried at room temperature in vacuo. The obtained crystal was measured by an infrared absorption (IR) spectrum, and determined to be 2,2′-azobis (2-methylbutanamidooxime). As a result of the differential thermal analysis, decomposition accompanied by heat generation occurred at 123 ° C., and the weight was rapidly reduced. This compound was found to be effective as a blowing agent having a decomposition point of 123 ° C.

Example 2 To 80 ml of 1,1'-azobis (cyclohexaneamidoxime) methanol, 24.4 g of 1,1'-azobis (cyclohexanenitrile) was added and stirred. At a temperature of 30 ° C., 33.0 g of a 50% aqueous solution of hydroxylamine was added dropwise over 5 minutes, followed by stirring at 20 to 25 ° C. for 48 hours to react. After the reaction, the mixture was concentrated under reduced pressure at 25 ° C. 40 ml of water was added, stirred, and filtered to obtain white crystals. As a result of IR measurement, it was determined to be 1,1′-azobis (cyclohexaneamide oxime). As a result of the differential thermal analysis, decomposition accompanied by heat generation occurred at 118 ° C., and the weight was rapidly reduced. This compound was found to be effective as a blowing agent having a decomposition point of 118 ° C.

Example 3 Polyvinyl chloride (for paste, SMILIT PX-N)
L) To 100 parts, 20 parts of 2,2'-azobis (2-methylbutanamidooxime), 50 parts of dioctyl phthalate, and 3 parts of calcium stearate are added and mixed well. The mixture is filled in a mold, sandwiched between presses having a hot plate heated to 170 ° C., and heated for 20 minutes.
Cool and take out and leave in an oven at 100 ° C. for 30 minutes to foam. The resulting foam has a specific gravity of 0.30,
It had uniform cells, a smooth surface, no stickiness, a very good appearance and no odor.

Example 4 2,2'-Azobis (2-methylbutanamide oxime)
Was foamed in the same manner as in Example 1 except that 1,1′-azobis (cyclohexaneamide oxime) was used instead of. The specific gravity of the foam is 0.33, having uniform cells,
The surface was smooth and very tacky with no stickiness and no odor remained.

Example 5 100 parts of thermosetting silicone rubber compound, 2,2 '
5 parts of azobis (2-methylbutanamide oxime),
0.5 parts of dicumyl peroxide, benzoyl peroxide
0.25 parts were mixed with a mixing roll, extruded into a tube by an extruder, and cut into a tube having a diameter of 2 cm and a length of 15 cm in a 250 ° C. oven for 5 minutes to foam. A foam having fine cells, a smooth surface and a favorable appearance was obtained. Its specific gravity is 0.35
Met.

Example 6 2,2'-Azobis (2-methylbutanamide oxime)
Was replaced with 1,1′-azobis (cyclohexaneamide oxime) to obtain a silicon sponge in the same manner as in Example 5. It had fine cells, a smooth surface, a good appearance and a specific gravity of 0.37.

[0025]

According to the present invention, a highly safe foaming agent which can be foamed at a low temperature and does not generate a bad odor, and a fine and uniform cell having a smooth surface and no tackiness obtained by using the same can be obtained. A foam having the same can be obtained.

Claims (2)

[Claims] 1. A blowing agent containing an azobisamide oxime represented by the general formula (1). Embedded image [In the formula, R ¹ represents an alkyl group having 1 to 6 carbon atoms. R ² represents an alkyl group having 2 to 6 carbon atoms. Alternatively, R ¹ and R ² are bonded to form a group — (CH ₂ ) ₅ —. ] 2. A foam obtained by foaming using the azobisamide oxime according to claim 1.