JP2018104613A - Foamable resin composition, and method for producing foam using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a foamable resin composition that inhibits the contamination of a work environment with formaldehyde, and reduces formaldehyde residues in a foam.SOLUTION: A foamable resin composition contains a raw material resin, a nitroso foaming agent, and an aldehyde scavenger. As the aldehyde scavenger used are at least one amine of a specific structure and at least one carboxylic acid of a specific structure, to produce a resin foam.SELECTED DRAWING: None

Description

  The present invention relates to a foamable resin composition and a method for producing a foam using the same.

  Conventionally, in the production of foams such as thermoplastic resins and elastomers, nitroso-based foaming agents such as N, N′-dinitrosopentamethylenetetramine, which are pyrolytic foaming agents, have been used.

  The nitroso-based blowing agent has a feature that a large amount of gas is generated and the decomposition temperature can be adjusted by adding urea, acid, or the like, but harmful formaldehyde is generated during decomposition. There is a concern that formaldehyde produced as a by-product may contaminate the work environment and harm the health of workers. In addition, by-product formaldehyde remains in the foam, which may deteriorate the quality of the foam or harm the health of the user.

  Formaldehyde is a typical odorous substance in the living environment, and since it has a very low odor threshold, it is known to cause unpleasant odors even at low concentrations, and to cause sick house syndrome and sick car syndrome. Furthermore, it is suspected to be carcinogenic and there is a risk of harm to health if a person is routinely exposed to these aldehydes. Therefore, it is regulated by the Ministry of Health, Labor and Welfare as 0.08 ppm as an indoor concentration guideline value. Accordingly, there has been a demand for a production method that suppresses contamination of the working environment by formaldehyde and reduces formaldehyde remaining in the foam.

  Various aldehyde scavengers have been proposed as a method for reducing formaldehyde (see, for example, Patent Documents 1 to 3). However, all of them have insufficient scavenging efficiency, poor mixing with rubber, and foam. There was a problem such as loss of quality.

JP-A-4-358536 JP 2010-6961 A JP 2012-120708 A

  The present invention has been made in view of the above-described background art, and suppresses contamination of the working environment due to formaldehyde and reduces the formaldehyde remaining in the foam, and expandable resin composition expandable resin composition, And it aims at providing the manufacturing method of a foam using the same.

  As a result of intensive studies to solve the above problems, the present inventors have found a foamable resin composition containing a specific amine and a carboxylic acid as an aldehyde scavenger, and have completed the present invention.

  That is, the present invention includes the following embodiments.

  [1] A foamable resin composition containing a raw material resin, a nitroso-based foaming agent, and an aldehyde scavenger, wherein the aldehyde scavenger is represented by any one of the following general formulas (1) to (4) A foamable resin composition comprising a seed amine and at least one carboxylic acid represented by the following general formula (5) or (6).

[In the above general formulas (1) to (3), each R ¹ independently represents a hydrogen atom, a methyl group, an ethyl group, a linear, branched or cyclic alkyl group having 3 to 8 carbon atoms, phenyl, Group, 2-aminoethyl group, 2-hydroxyethyl group, 2-hydroxy-n-propyl group, 3-hydroxy-n-propyl group, or 2,3-dihydroxy-n-propyl group, ) And (3), at least one of R ¹ represents a hydrogen atom. ]

[In the general formula (4), X represents a methylene group, an oxygen atom, or an N—R ¹ group, and each R ¹ independently represents a hydrogen atom, a methyl group, an ethyl group, or a straight chain having 3 to 8 carbon atoms. A chain, branched or cyclic alkyl group, phenyl group, 2-aminoethyl group, 2-hydroxyethyl group, 2-hydroxy-n-propyl group, 3-hydroxy-n-propyl group, or 2,3- Represents a dihydroxy-n-propyl group. ]

In above general formula (5), ^{R 2} is represents the number 6-18 linear, branched or cyclic alkyl group, or an aryl group having 6 to 14 carbon atoms. ]

[In the said General formula (6), L represents a C1-C8 alkylene group or a C6-C10 arylene group. ]
[2] The amine is ethylenediamine, N-methylethylenediamine, N, N-dimethylethylenediamine, N, N′-dimethylethylenediamine, N, N, N′-trimethylethylenediamine, N-ethylethylenediamine, N, N-diethylethylenediamine, N, N′-diethylethylenediamine, N, N, N′-triethylethylenediamine, piperazine, N-methylpiperazine, N-ethylpiperazine, N- (2-aminoethyl) piperazine, and N- (2,3-dihydroxy- The foamable resin composition as described in [1] above, which is at least one amine selected from the group consisting of (n-propyl) piperazine.

  [3] Carboxylic acid is hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberin The foamable resin composition as described in [1] or [2] above, which is one or more carboxylic acids selected from the group consisting of acids, azelaic acid, and sebacic acid.

  [4] The foamable resin composition according to any one of [1] to [3], wherein the nitroso-based foaming agent is N, N′-dinitrosopentamethylenetetramine.

  [5] The foamable resin composition according to any one of the above [1] to [4], wherein the raw material resin is one or two or more resins selected from the group consisting of thermoplastic resins and elastomers. object.

  [6] A method for producing a foam, comprising heating and foaming the foamable resin composition according to any one of [1] to [5].

  [7] The production method according to the above [6], wherein the foam is foamed rubber.

  According to the present invention, contamination of the working environment due to formaldehyde generated during thermal decomposition of a nitroso-based foaming agent is suppressed, and formaldehyde remaining in the foam is reduced. As a result, it is possible to reduce aldehydes that are harmful to the human body and improve the human living environment.

  The foamable resin composition of the present invention is a foamable resin composition containing a raw material resin, a nitroso-based foaming agent, and an aldehyde scavenger, and the aldehyde scavenger is any of the following general formulas (1) to (4). And at least one carboxylic acid represented by the following general formula (5) or (6).

In the general formulas (1) to (3), each R ¹ is independently a hydrogen atom, a methyl group, an ethyl group, a linear, branched or cyclic alkyl group having 3 to 8 carbon atoms, or a phenyl group. , 2-aminoethyl group, 2-hydroxyethyl group, 2-hydroxy-n-propyl group, 3-hydroxy-n-propyl group, or 2,3-dihydroxy-n-propyl group, represented by the general formula (2) In (3), at least one of R ¹ represents a hydrogen atom. In the general formula (4), X represents a methylene group, an oxygen atom, or an N—R ¹ group (R ¹ has the same definition as above).

  The alkyl group having 3 to 8 carbon atoms may be linear, branched or cyclic, such as an n-propyl group, an n-butyl group, an n-pentyl group, an n-hexyl group, n-heptyl group, n-octyl group, i-propyl group, i-butyl group, t-butyl group, 2-ethylpropyl group, 2-ethylhexyl group, cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, etc. Can be mentioned.

  Specific examples of the amine represented by any one of the general formulas (1) to (4) include ethylenediamine, N-methylethylenediamine, N, N-dimethylethylenediamine, N, N′-dimethylethylenediamine, N, N, N′-trimethylethylenediamine, N-ethylethylenediamine, N, N-diethylethylenediamine, N, N′-diethylethylenediamine, N, N, N′-triethylethylenediamine, piperazine, N-methylpiperazine, N-ethylpiperazine, It is preferably at least one amine selected from the group consisting of N- (2-aminoethyl) piperazine and N- (2,3-dihydroxy-n-propyl) piperazine.

In the general formula (5), R ² represents a linear, branched or cyclic alkyl group having 6 to 18 carbon atoms or an aryl group having 6 to 14 carbon atoms. Moreover, in the said General formula (6), L represents a C1-C8 alkylene group or a C6-C10 arylene group.

  The alkyl group having 6 to 18 carbon atoms may be linear, branched or cyclic. For example, an n-hexyl group, an n-heptyl group, an n-octyl group, an n-nonyl group, Examples include capryl group, lauryl group, myristyl group, palmityl group, stearyl group, 2-ethylhexyl group, and cyclohexyl group.

  Examples of the aryl group having 6 to 14 carbon atoms include a phenyl group, a 1-naphthyl group, a 2-naphthyl group, a 1-anthranyl group, a 2-anthranyl group, and a 9-anthranyl group.

  Examples of the alkylene group having 2 to 8 carbon atoms include a methylene group, an ethylene group, a propylene group, a butylene group, a pentylene group, a hexylene group, a heptylene group, and an octylene group.

  Examples of the arylene group having 6 to 10 carbon atoms include 1,2-phenylene group, 1,3-phenylene group, 1,4-phenylene group, 1,4-naphthylene group, 2,3-naphthylene group, 2, Examples include 6-naphthylene group and 2,7-naphthylene group.

  Specific examples of the carboxylic acid represented by the general formula (5) or (6) include hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, capric acid, lauric acid, myristic acid, palmitic acid, and stearic acid. And at least one carboxylic acid selected from the group consisting of malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, and sebacic acid.

  The ratio of the amine and carboxylic acid is not particularly limited, but the molar ratio of the amino group of the amine and the carboxyl group of the carboxylic acid is preferably in the range of 1/2 to 2/1. If the molar amount of the amino group is too large relative to the molar amount of the carboxyl group, it may cause an amine odor or inhibit the rubber crosslinking reaction. Moreover, when there are too many mole amounts of a carboxyl group with respect to the mole amount of an amino group, acidity will become high and may affect the decomposition temperature of a nitroso type | system | group foaming agent.

  The nitroso-based blowing agent can be used without particular limitation, and examples thereof include N, N′-dinitrosopentamethylenetetramine.

  In the present invention, as the aldehyde scavenger, in addition to the above-described amine and carboxylic acid, an existing aldehyde scavenger may be used in combination. Although it does not specifically limit as an existing aldehyde scavenger, For example, urea, ethylene urea, adipic acid dihydrazide etc. are mentioned.

  Although it does not specifically limit as raw material resin in this invention, For example, a thermoplastic resin, an elastomer, etc. are mentioned.

  Examples of the thermoplastic resin include polyvinyl chloride, vinyl chloride copolymers, polyolefins such as polyethylene and polypropylene, ethylene / propylene copolymers, acrylonitrile / butadiene / styrene copolymers, and the like.

  Examples of the elastomer include natural rubber, polyisoprene rubber, styrene / butadiene copolymer rubber, acrylonitrile / butadiene copolymer rubber, acrylic rubber, fluorine rubber, ethylene vinyl acetate copolymer rubber, ethylene propylene rubber, and ethylene propylene diene rubber. And thermoplastic elastomers.

  In the foaming polymer composition of the present invention, the above-mentioned raw resin may be used alone or in combination of two or more.

  The content ratio of the raw material resin described above in the foamable resin composition of the present invention is not particularly limited. For example, it is 1 to 99% by weight, preferably 1 to 95% by weight, more preferably, per total amount of the foamable resin composition. Is 1 to 90% by weight.

  In the foamable resin composition of the present invention, when a thermoplastic resin is used as the raw material resin, a crosslinking agent may be included. When the foaming resin composition of the present invention contains a crosslinking agent, the content of the crosslinking agent is not particularly limited. For example, the crosslinking agent is preferably 0.1 to 10 parts by weight per 100 parts by weight of the thermoplastic resin. Is 0.5 to 1.5 parts by weight.

  Moreover, in the foamable resin composition of this invention, when using an elastomer as raw material resin, the vulcanizing agent may be contained. When the vulcanizing agent is contained in the foamable resin composition of the present invention, the content of the vulcanizing agent is not particularly limited. For example, the vulcanizing agent is 0.1 to 20 parts by weight per 100 parts by weight of the elastomer, Preferably it is 0.1-10 weight part.

  The expandable resin composition of the present invention of the present invention may contain conventionally known additives such as a reinforcing material, a filler, a colorant, a softening agent, an activator, etc., as necessary, in addition to the above components. Good.

  In the present invention, the aldehyde scavenger and the nitroso foaming agent are preferably mixed with the raw material resin in advance in order to effectively capture the aldehyde.

  A foam can be obtained by heating and foaming the above expandable resin composition of the present invention above the decomposition temperature of the nitroso foaming agent used.

  The method for producing a foam using the foamable resin composition of the present invention may be a general heat foaming method, the type of raw resin used, the composition of the nitroso-based foaming agent used, It is set as appropriate according to the type of component. Specific examples of the method for heating and foaming the foamable resin composition of the present invention include a pressure foaming method, a normal pressure foaming method, an extrusion foaming method, and an injection foaming method.

  The foam obtained from the foamable resin composition of the present invention is not particularly limited as long as it is a foam to which a nitroso-based foaming agent can be applied. Specifically, foamed rubber, foamed EVA (ethylene vinyl acetate copolymer) ) And the like.

  Hereinafter, the present invention will be specifically described, but the present invention is not construed as being limited to these examples.

(Analysis method)
The aldehyde concentration is determined by adsorbing the target gas on a cartridge (product name: Presep-C DNPH, manufactured by Wako Pure Chemical Industries, Ltd.) carrying 2,4-dinitrophenylhydrazine (DNPH), and DNPH-aldehyde condensate from the cartridge with acetonitrile. The DNPH-aldehyde condensate in the eluate was quantified and calculated with a liquid chromatograph (device name: Agilent 1220 Infinity LC, manufactured by Agilent Technologies).

(Abbreviation)
The following abbreviations are used in the examples.

FA: formaldehyde AEP: N- (2-aminoethyl) piperazine DHPP: N- (2,3-dihydroxy n-propyl) piperazine EDA: 1,2-ethylenediamine Example 1. (Manufacture of foam rubber)
[Step A] The compounds shown in Table 1 were kneaded with a 3.6 L Banbury mixer (manufactured by Kobe Steel).

  [Step B] Further, the compounds shown in Table 2 were kneaded with a steam type 8 inch open roll (manufactured by Kansai Roll Co., Ltd.) to obtain a foam rubber raw material.

[Step C] Using a test vulcanizing press (made by Mie Kogyo Co., Ltd., mold size: 80 mm × 80 mm × 7 mm), the foam rubber raw material obtained in Step B is vapor pressure 3.8 kg / cm ² , press pressure 100 kg / Foamed rubber was obtained by foaming at cm 2 for 15 minutes.

Examples 2 to 8 and Comparative Examples 1 and 3. (FA emission assessment)
(FA emission amount during foaming) After 1 g of the foamed rubber raw material obtained in Step B of Example 1 was sealed in a Tedlar bag and degassed under reduced pressure, 1 L of air was injected. The Tedlar bag was allowed to stand at 150 ° C. for 1 hour for chemical foaming, and the amount of FA emitted per gram of rubber was calculated from the formaldehyde concentration in the Tedlar bag.

  (Amount of foam FA diffused) 10 g of the foamed rubber obtained in Step C of Example 1 was divided into 16 equal parts, sealed in a Tedlar bag and degassed under reduced pressure, and then 1 L of air was injected. After this Tedlar bag was allowed to stand at 60 ° C. for 2 hours, the amount of FA emitted per gram of rubber was calculated from the formaldehyde concentration in the Tedlar bag.

Comparative Example 2
In Step B of Example 1, as a result of using piperazine as an aldehyde scavenger, unmixed particles of piperazine were confirmed in the rubber, and it was judged that mixing was poor, and further evaluation was stopped.

  The result of Examples 2-8 and Comparative Examples 1-3 is combined with Table 3, and is shown.

  As is apparent from Table 3, the production method of the present invention reduced both the amount of FA emitted during foaming of rubber and the amount of FA emitted from the obtained foam.

Claims (7)

A foamable resin composition comprising a raw material resin, a nitroso foaming agent, and an aldehyde scavenger, wherein the aldehyde scavenger is represented by any one of the following general formulas (1) to (4): And a foamable resin composition comprising at least one carboxylic acid represented by the following general formula (5) or (6).

[In the above general formulas (1) to (3), each R ¹ independently represents a hydrogen atom, a methyl group, an ethyl group, a linear, branched or cyclic alkyl group having 3 to 8 carbon atoms, phenyl, Group, 2-aminoethyl group, 2-hydroxyethyl group, 2-hydroxy-n-propyl group, 3-hydroxy-n-propyl group, or 2,3-dihydroxy-n-propyl group, ) And (3), at least one of R ¹ represents a hydrogen atom. ]

[In the general formula (4), X represents a methylene group, an oxygen atom, or an N—R ¹ group, and each R ¹ independently represents a hydrogen atom, a methyl group, an ethyl group, or a straight chain having 3 to 8 carbon atoms. A chain, branched or cyclic alkyl group, phenyl group, 2-aminoethyl group, 2-hydroxyethyl group, 2-hydroxy-n-propyl group, 3-hydroxy-n-propyl group, or 2,3- Represents a dihydroxy-n-propyl group. ]

In above general formula (5), ^{R 2} is represents the number 6-18 linear, branched or cyclic alkyl group, or an aryl group having 6 to 14 carbon atoms. ]

[In the said General formula (6), L represents a C1-C8 alkylene group or a C6-C10 arylene group. ] The amine is ethylenediamine, N-methylethylenediamine, N, N-dimethylethylenediamine, N, N′-dimethylethylenediamine, N, N, N′-trimethylethylenediamine, N-ethylethylenediamine, N, N-diethylethylenediamine, N, N '-Diethylethylenediamine, N, N, N'-triethylethylenediamine, piperazine, N-methylpiperazine, N-ethylpiperazine, N- (2-aminoethyl) piperazine, and N- (2,3-dihydroxy-n-propyl The foamable resin composition according to claim 1, wherein the foamable resin composition is one or more amines selected from the group consisting of piperazine. Carboxylic acid is hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelain The foamable resin composition according to claim 1 or 2, wherein the foamable resin composition is one or more carboxylic acids selected from the group consisting of an acid and sebacic acid. The foamable resin composition according to any one of claims 1 to 3, wherein the nitroso-based foaming agent is N, N'-dinitrosopentamethylenetetramine. The foamable resin composition according to any one of claims 1 to 4, wherein the raw material resin is one or two or more resins selected from the group consisting of thermoplastic resins and elastomers. A method for producing a foam, comprising heating and foaming the foamable resin composition according to any one of claims 1 to 5. The production method according to claim 6, wherein the foam is foamed rubber.