JP5598193B2 - Foam composition and foam - Google Patents

Description

  The present invention relates to a foam composition and a foam. More specifically, the present invention relates to a thermoplastic elastomer having characteristics (hereinafter sometimes referred to as “recyclability”) capable of repeatedly reproducing cross-linking and dissociation by temperature change. The present invention relates to a foam composition.

In recent years, reuse of used materials is desired from the standpoints of environmental protection and resource saving.
Crosslinked rubber (vulcanized rubber) exhibits a very high strength because it has a stable three-dimensional network structure in which a polymer substance and a crosslinking agent (vulcanizing agent) are covalently bonded. It is known that molding is difficult.
On the other hand, thermoplastic elastomers utilize physical crosslinking and are known to be easily molded by heating and melting without the need for complicated vulcanization / molding steps including preforming. Yes.
A typical example of such a thermoplastic elastomer includes a resin component and a rubber component. At room temperature, the microcrystalline resin component serves as a hard segment that serves as a cross-linking point of a three-dimensional network structure. 2. Description of the Related Art Thermoplastic elastomers that prevent plastic deformation of a segment) and plastically deform by softening or melting of a resin component by increasing temperature are known.
However, when such a thermoplastic elastomer is blended with a filler or the like and used as a composition, the hardness and density become too high, the mass and specific gravity increase accordingly, and it is released after being compressed for a predetermined time. Since the compression set at that time may not be sufficient, it has been difficult to use it for foams such as cap materials and packing materials.

  In order to solve such a problem, the present applicant has disclosed in Patent Document 1 “a heat having a side chain containing at least one selected from the group consisting of an imino group, a nitrogen-containing heterocyclic ring and a covalently bonded crosslinking site and a carbonyl-containing group. The composition for foams containing the plastic elastomer (A) and the foaming agent (D) is proposed.

International Publication No. 2006/090687

  However, the present inventor conducted further studies on the foam composition described in Patent Document 1, and found that the expansion ratio and the physical properties such as tensile strength, tear strength, and compression set resistance after foaming. It was clarified that there is room for improvement in both of these.

  Then, this invention makes it a subject to provide the composition for foams which has high foaming ratio and is excellent also in physical properties, such as the tensile strength after foaming, tear strength, and compression set.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that a foam of a foam composition containing a thermoplastic elastomer having a side chain containing a predetermined structure and a thermally expandable microcapsule has high foaming. It has been found that it has a magnification and is excellent in physical properties such as tensile strength after foaming, tear strength, and compression set, and has achieved the present invention. That is, the present invention provides the following (a) to (i).

(A) A composition for a foam comprising a thermoplastic elastomer (A) having a side chain containing a nitrogen-containing heterocyclic ring and a carbonyl group, and a thermally expandable microcapsule (B),
The composition for foams whose content of the said thermally expansible microcapsule (B) is 0.01-20 mass% with respect to the whole mass of the said foaming composition.

  (B) The thermally expandable microcapsule (B) includes an outer shell made of a thermoplastic resin, and a foaming agent encapsulated in the outer shell and having a boiling point equal to or lower than the softening point of the thermoplastic resin. The foam composition as described in (a) above, which is a thermally expandable microsphere.

  (C) The foam composition according to (a) or (b), wherein the elastomer constituting the main chain of the thermoplastic elastomer (A) is polypropylene rubber.

  (D) The foam composition according to (b) or (c), wherein the thermoplastic resin forming the outer shell of the thermally expandable microcapsule (B) is a nitrile polymer.

(E) The foam composition according to any one of (a) to (d), wherein the side chain of the thermoplastic elastomer (A) contains a structure represented by the following formula (1).

Wherein A is a nitrogen-containing heterocyclic ring, B is a single bond; an oxygen atom, an amino group NR ′ (R ′ is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms) or a sulfur atom; or these An organic group that may contain any atom or group of

(F) The above side chain containing a structure represented by the following formula (2) or (3) in which the side chain containing the structure represented by the above formula (1) is bonded to the main chain at the α-position or the β-position ( The composition for foams as described in e).

(Wherein A is a nitrogen-containing heterocyclic ring, B and D are each independently a single bond; an oxygen atom, an amino group NR ′ (R ′ is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms)) or A sulfur atom; or an organic group that may contain these atoms or groups.)

  (G) The composition for a foam according to any one of (a) to (f), wherein the nitrogen-containing heterocycle is isocyanuric acid.

  (H) The foam composition according to any one of (a) to (g), wherein at least a part of the thermoplastic elastomer (A) is cross-linked with each other via the nitrogen-containing heterocycle.

  (I) A foam obtained by foaming the foam composition according to any one of (a) to (h).

  As described below, according to the present invention, there is provided a composition for a foam having a high expansion ratio and excellent physical properties such as tensile strength after foaming, tear strength and compression set. Can do.

The present invention is described in detail below.
The foam composition of the present invention is a foam composition comprising a thermoplastic elastomer (A) having a side chain containing a nitrogen-containing heterocyclic ring and a carbonyl group, and a thermally expandable microcapsule (B). And it is a composition for foams whose content of the said thermally expansible microcapsule (B) is 0.01-20 mass% with respect to the whole mass of the said foaming composition.
Hereinafter, the thermoplastic elastomer (A) and the thermal expansion microcapsule (B) used in the foam composition of the present invention will be described in detail.

<Thermoplastic elastomer (A)>
The thermoplastic elastomer (A) used in the foam composition of the present invention has a main chain which is an elastomer and has a side chain containing a nitrogen-containing heterocyclic group and a carbonyl group.

The elastomer constituting the main chain of the thermoplastic elastomer (A) is not particularly limited, and may be either a natural polymer or a synthetic polymer, and is a polymer having a glass transition point of room temperature (25 ° C.) or lower. Is preferred.
Specific examples of the elastomer include natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), 1,2-butadiene rubber, styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber ( NBR), chloroprene rubber (CR), butyl rubber (IIR), diene rubbers such as ethylene-propylene-diene rubber (EPDM) and hydrogenated products thereof; ethylene-propylene rubber (EPM), ethylene-acrylic rubber (AEM), Olefinic rubbers such as ethylene-butene rubber (EBM), chlorosulfonated polyethylene, acrylic rubber, fluororubber, polyethylene rubber, polypropylene rubber, and the like. These may be used alone or in combination of two or more. May be.
Of these, olefin-based rubber is preferable because the deterioration of the foam composition is suppressed and the tensile strength of the foam becomes better, and among them, the viscosity of the foam composition is lowered and the extrusion is performed. Polypropylene rubber is preferred because the workability by foaming is good.

The elastomer may be liquid or solid, and its molecular weight is not particularly limited, and the foam composition of the present invention, the use of the foam of the present invention, and physical properties required for these, etc. It can be selected as appropriate according to the conditions.
The fluidity when the foam composition of the present invention and the foam of the present invention (hereinafter, these may be collectively referred to as “the foam (composition) of the present invention”) is heated (decrosslinked). In the case of importance, the elastomer is preferably in a liquid state. For example, in the case of an olefin rubber such as polypropylene rubber, the weight average molecular weight is preferably 1,000 to 50,000, and 5,000 to 30,000. It is particularly preferred that
On the other hand, when emphasizing the strength of the foam (composition) of the present invention, the elastomeric polymer is preferably solid. For example, an olefin rubber such as polypropylene rubber has a weight average molecular weight of 10,000. It is preferable that it is -1,000,000, and it is especially preferable that it is 50,000-500,000.
In the present invention, the weight average molecular weight is a weight average molecular weight (in terms of polystyrene) measured by gel permeation chromatography (GPC). For the measurement, tetrahydrofuran (THF) is preferably used as a solvent.

In the present invention, two or more of the above elastomers can be mixed and used. In this case, the mixing ratio of the respective elastomers may be any ratio depending on the use of the foam (composition) of the present invention, the physical properties required for the foam (composition) of the present invention, and the like. it can.
Further, the glass transition point of the elastomer is preferably 25 ° C. or less as described above, and when the elastomer has two or more glass transition points or when two or more kinds of the elastomers are used in combination, At least one of the glass transition points is preferably 25 ° C. or lower.
When the glass transition point of the elastomer is within this range, a molded product made of the foam (composition) of the present invention is preferable because it exhibits rubber-like elasticity at room temperature.
In the present invention, the glass transition point is a glass transition point measured by differential scanning calorimetry (DSC-Differential Scanning Calorimetry). The temperature raising rate is preferably 10 ° C./min.

The thermoplastic elastomer (A) is one in which the elastomer has a side chain containing a nitrogen-containing heterocyclic ring and a carbonyl group.
Here, the “side chain” refers to the side chain and / or terminal of the elastomer.
Further, “having a side chain containing a nitrogen-containing heterocycle and a carbonyl group” means that the atom (usually a carbon atom, the same shall apply hereinafter) forming the main chain of the elastomer contains a nitrogen-containing heterocycle and a carbonyl group. It is said that the side chain containing is chemically bonded (for example, covalent bond, etc., the same applies hereinafter).

  In this invention, it is preferable that the side chain which the said thermoplastic elastomer (A) has contains the structure represented by following formula (1).

  In the above formula (1), A is a nitrogen-containing heterocyclic ring, B is a single bond; an oxygen atom, an amino group NR ′ (R ′ is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms) or a sulfur atom. Or an organic group that may contain these atoms or groups.

Here, A in the above formula (1) is a nitrogen-containing heterocyclic ring, but as described later, at least a part of the thermoplastic elastomer (A) is crosslinked (covalently bonded) via the nitrogen-containing heterocyclic ring. When it is, the nitrogen-containing heterocycle has a bond that is bonded to the side chain of the other thermoplastic elastomer (A).
Examples of the nitrogen-containing heterocycle include isocyanuric acid (for example, a trimer of an isocyanate group-containing compound) in addition to those described in paragraphs [0083] to [0091] of Patent Document 1.
Among these, in the present invention, isocyanuric acid is preferable because physical properties such as tensile properties after foaming, tear strength, and compression set resistance are improved.

  Moreover, as isocyanuric acid which is a suitable aspect of a nitrogen-containing heterocyclic ring, what is represented by following formula (4) is mentioned, for example.

In the above formula (4), R ¹ , R ² and R ³ are each independently a hydrogen atom; an alkyl group such as a methyl group or an ethyl group; an alkoxy group such as a methoxy group or an ethoxy group; a hydroxymethyl group or hydroxyethyl Represents a hydroxyl group-containing group such as a group; a halogen atom such as a chlorine atom or a bromine atom; a hydroxy group; a cyano group; an amino group; an ester group; or an ether group, but as described later, at least of the thermoplastic elastomer (A) When a part is bridged (covalently bonded) via a nitrogen-containing heterocycle, one or more of R ¹ , R ² and R ³ are bonded to the side chain of the other thermoplastic elastomer (A). It has a bond having a bond (for example, an alkylene group such as a methylene group or an ethylene group; an alkylene ether group such as a methylene ether group or an ethylene ether group; etc.).

  Specific examples of the isocyanuric acid represented by the above formula (4) include 1,3,5-tris (2-hydroxyethyl) isocyanuric acid and the side chain of the other thermoplastic elastomer (A). And the like combined with

On the other hand, as B in the above formula (1), specifically, for example, a single bond; an oxygen atom, an amino group NR ′ (R ′ is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms) or a sulfur atom; An alkylene group having 1 to 20 carbon atoms or an aralkylene group which may contain these atoms or groups; an alkylene ether group having 1 to 20 carbon atoms having these atoms or groups at its terminal (an alkyleneoxy group such as —O— CH ₂ CH ₂ — group), alkyleneamino group (eg —NH—CH ₂ CH ₂ — group etc.) or alkylene thioether group (alkylenethio group, eg —S—CH ₂ CH ₂ — group); And an aralkylene ether group having 1 to 20 carbon atoms (aralkyleneoxy group), an aralkyleneamino group, or an aralkylenethioether group.

Here, the alkyl group having 1 to 10 carbon atoms of the amino group NR ′ includes methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, including isomers. Group, decyl group and the like.
In addition, the oxygen atom, sulfur atom and amino group NR ′ of B in the above formula (1); and; an alkylene ether group, alkyleneamino group, alkylenethioether having 1 to 20 carbon atoms terminated with these atoms or groups Group, or an oxygen atom such as an aralkylene ether group, an aralkylene amino group, an aralkylene thioether group, an amino group NR ′ and a sulfur atom are combined with an adjacent carbonyl group to form a conjugated ester group, amide group or imide group. It is preferable to form a thioester group or the like.
Among these, B in the above formula (1) represents an oxygen atom, a sulfur atom or an amino group forming a conjugated system; an alkylene ether group having 1 to 20 carbon atoms and alkylene having these atoms or groups at the terminal It is preferably an amino group or an alkylene thioether group, and an amino group (NH), an alkyleneamino group (—NH—CH ₂ — group, —NH—CH ₂ CH ₂ — group, —NH—CH ₂ CH ₂ CH ₂ — Group) and an alkylene ether group (—O—CH ₂ — group, —O—CH ₂ CH ₂ — group, —O—CH ₂ CH ₂ CH ₂ — group) are particularly preferred.

  Further, in the present invention, the thermoplastic elastomer (A) has the following formula (2) or a side chain containing a structure represented by the formula (1) bonded to the main chain at the α-position or the β-position. It is more preferable to have it as a side chain containing the structure represented by (3).

  In the above formulas (2) and (3), A is a nitrogen-containing heterocyclic ring, B and D are each independently a single bond; an oxygen atom, an amino group NR ′ (R ′ is a hydrogen atom or a C 1-10 carbon atom) An alkyl group) or a sulfur atom; or an organic group that may contain these atoms or groups.

Here, A in the above formulas (2) and (3) is basically the same as A (nitrogen-containing heterocycle) in the above formula (1).
Further, B and D in the above formulas (2) and (3) are basically the same as B (organic group) in the above formula (1).
However, D in the above formula (3) forms a conjugated system with a single bond; an imide nitrogen of an alkylene group having 1 to 20 carbon atoms or an aralkylene group which may contain an oxygen atom, an amino group NR ′ or a sulfur atom. And a single bond is particularly preferable.

  In the present invention, the side chain of the thermoplastic elastomer (A) (specifically, the side chain containing the structure represented by the above formula (1) or the above formula (2) or (3)) is It is preferably introduced at a ratio (introduction ratio) of 0.1 to 50 mol% with respect to 100 mol% of the monomer constituting the elastomer. If it is less than 0.1 mol%, the strength at the time of crosslinking may not be sufficient, and if it exceeds 50 mol%, the crosslinking density may increase and rubber elasticity may be lost. When the introduction ratio is within this range, the interactions between the side chains of the elastomer occur between molecules or within the molecule, and these are formed in a well-balanced manner. Therefore, the resulting foam (composition) of the present invention is crosslinked. High tensile strength, excellent recyclability, and good compression set resistance. From the viewpoint that these properties are more excellent, it is more preferable that side chains are introduced at a ratio of 0.1 to 30 mol%, and side chains are introduced at a ratio of 0.5 to 20 mol%. Further preferred.

Further, in the present invention, the thermoplastic elastomer (A) has a better compression set resistance and higher mechanical strength, so that at least a part of the thermoplastic elastomer (A) is cross-linked with each other via the nitrogen-containing heterocycle. It is preferable.
Here, the crosslinking may be either intramolecular or intermolecular.
In addition, the specific mode of crosslinking is not particularly limited, and may be, for example, hydrogen bonding crosslinking (see the following reaction formula (5)) between nitrogen atoms constituting the ring of the nitrogen-containing heterocyclic ring, and the above heat When producing the plastic elastomer (A), a cyclic acid anhydride group and a cyclic acid anhydride group among the compounds capable of introducing a nitrogen-containing heterocycle described later with respect to the elastomeric polymer containing a cyclic acid anhydride group described later in the side chain; Formed by reacting a compound having two or more reactive substituents (for example, hydroxyl group, thiol group, amino group, etc.) (for example, 1,3,5-tris (2-hydroxyethyl) isocyanuric acid described above). Or a covalent cross-linking (see the following reaction formulas (6) and (7)).

The manufacturing method of the thermoplastic elastomer (A) used for the composition for foams of this invention is not specifically limited, A normal method can be selected.
Specifically, the method described in paragraph [0138] of Patent Document 1, that is, a reaction step in which a compound capable of introducing a nitrogen-containing heterocyclic ring is reacted with an elastomeric polymer containing a cyclic acid anhydride group in the side chain. A production method comprising
Further, the elastomeric polymer containing a cyclic acid anhydride group in the side chain used in the reaction step and the compound capable of introducing a nitrogen-containing heterocyclic ring are described in paragraphs [0139] to [0140] of [Patent Document 1] and [0140], respectively. [0142] Those described in the paragraph can be used.
Similarly, the reaction step can be performed under the conditions described in paragraph [0144] of Patent Document 1.

<Thermal expansion microcapsule (B)>
The thermal expansion microcapsule (B) used in the foam composition of the present invention is particularly limited as long as it is a thermally expandable microsphere having a structure in which a thermoplastic resin is used as an outer shell and a foaming agent is enclosed therein. Not.

The thermoplastic resin is not particularly limited as long as it is a thermoplastic resin polymerized from a (radical) polymerizable monomer having one polymerizable double bond.
Specific examples of the polymerizable monomer include nitrile monomers such as acrylonitrile, methacrylonitrile, α-chloroacrylonitrile, α-ethoxyacrylonitrile, fumaronitrile; acrylic acid, methacrylic acid, itaconic acid, Carboxyl group-containing monomers such as maleic acid, fumaric acid and citraconic acid; vinyl halide monomers such as vinylidene chloride, vinyl chloride, vinyl bromide and vinyl fluoride; vinyl acetate, vinyl propionate and vinyl butyrate Vinyl ester monomers: methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, propyl (meth) acrylate, n- Octyl (meth) acrylate, dodecyl (meta ) Acrylate, 2-ethylhexyl (meth) acrylate, stearyl (meth) acrylate, 2-chloroethyl (meth) acrylate, phenyl (meth) acrylate, isobornyl (meth) acrylate, cyclohexyl (meth) acrylate, benzyl (meth) acrylate, β -(Meth) acrylic acid ester monomers such as carboxyethyl acrylate, 2-hydroxyethyl (meth) acrylate and 2-hydroxypropyl (meth) acrylate; acrylamides such as acrylamide, substituted acrylamide, methacrylamide and substituted methacrylamide Monomer; Maleimide monomer such as N-phenylmaleimide, N- (2-chlorophenyl) maleimide, N-cyclohexylmaleimide, N-laurylmaleimide; , Α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, pn-butylstyrene, p-tert-butylstyrene, pn -Hexyl styrene, pn octyl styrene, pn-nonyl styrene, pn-decyl styrene, pn-dodecyl styrene, n-methoxy styrene, p-phenyl styrene, chlorostyrene, 3,4-dichloro Styrene monomers such as styrene; Ethylene unsaturated monoolefin monomers such as ethylene, propylene, butylene and isobutylene; Vinyl ether monomers such as vinyl methyl ether, vinyl ethyl ether and vinyl isobutyl ether; Vinyl methyl ketone , Vinyl hexyl ketone, methyl isopropenyl keto Vinyl ketone monomers such as N-vinyl pyrrole, N-vinyl carbazole, N-vinyl indole, N-vinyl pyrrolidone and other N-vinyl monomers; vinyl naphthalene salts; and the like. You may use independently and may use 2 or more types together.
Here, in the carboxyl group-containing monomer, some or all of the carboxyl groups may be neutralized during polymerization. Moreover, (meth) acryl means acryl or methacryl. The maleimide monomer is preferably an N-substituted maleimide monomer having a structure having a substituent on a nitrogen atom.

  Among these, as the polymerizable monomer, nitrile monomers, (meth) acrylate monomers, carboxyl group-containing monomers, styrene monomers, vinyl acetate, acrylamide monomers And a maleimide monomer or a vinyl halide monomer.

In particular, it is preferable to use a nitrile monomer as the polymerizable monomer because the heat resistance and solvent resistance of the outer shell made of the resulting thermoplastic resin (nitrile polymer) are improved.
Moreover, it is preferable to further use a vinyl halide monomer and / or a (meth) acrylic acid ester monomer together with the nitrile monomer as the polymerizable monomer.
Moreover, it is preferable to use a vinyl halide monomer as the polymerizable monomer because the gas barrier property of the outer shell made of the resulting thermoplastic resin (vinyl halide polymer) is improved.
Moreover, it is preferable to use a (meth) acrylic acid ester monomer as the polymerizable monomer because the expansion behavior of the resulting thermally expanded microcapsule (B) can be easily controlled.
In addition, when a carboxyl group-containing monomer is used together with a nitrile monomer as the polymerizable monomer, the heat resistance and solvent resistance of the outer shell are improved and the glass transition temperature of the thermoplastic resin is increased. The thermal expansion microcapsule (B) is preferable because it can be thermally expanded at a high temperature.
Further, as the polymer monomer, a vinyl halide monomer and / or a (meth) acrylic acid ester monomer may be further used together with a nitrile monomer and a carboxyl group-containing monomer.
Moreover, it is preferable to use a maleimide monomer in combination as the polymer monomer because the thermal expansion microcapsule (B) is less colored.

  On the other hand, the foaming agent is not particularly limited as long as it is a substance that is vaporized or expanded by heat to generate a gas, but is preferably a substance having a boiling point lower than the softening point of the thermoplastic resin. , Hydrocarbons having 1 to 12 carbon atoms and their halides; having an ether structure and not containing chlorine and bromine atoms, fluorine-containing compounds having 2 to 10 carbon atoms; tetraalkylsilanes; And the like. These may be used singly or in combination of two or more.

Specific examples of the hydrocarbon having 1 to 12 carbon atoms include propane, cyclopropane, propylene, butane, normal butane, isobutane, cyclobutane, normal pentane, cyclopentane, isopentane, neopentane, normal hexane, isohexane, and cyclohexane. , Heptane, cycloheptane, octane, isooctane, cyclooctane, 2-methylpentane, 2,2-dimethylbutane, petroleum ether and the like. These hydrocarbons may be linear, branched or alicyclic, and are preferably aliphatic.
Specific examples of the hydrocarbon halide having 1 to 12 carbon atoms include methyl chloride, methylene chloride, chloroform, and carbon tetrachloride.

Specific examples of the fluorine-containing compound having an ether structure and not containing a chlorine atom and a bromine atom and having 2 to 10 carbon atoms include C ₃ H ₂ F ₇ OCF ₂ H, C ₃ HF ₆ OCH _{3, and the like.} C ₂ HF ₄ OC ₂ H ₂ F ₃ , C ₂ H ₂ F ₃ OC ₂ H ₂ F ₃ , C ₄ HF ₈ OCH ₃ , C ₃ H ₂ F ₅ OC ₂ H ₃ F ₂ , C ₃ HF ₆ OC ₂ H ₂ F ₃ , C ₃ H ₃ F ₄ OCHF ₂ , C ₃ HF ₆ OC ₃ H ₂ F ₅ , C ₄ H ₃ F ₆ OCHF ₂ , C ₃ H ₃ F ₄ OC ₂ HF ₄ , C ₃ HF ₆ Hydrofluoroethers such as OC ₃ H ₃ F ₄ , C ₃ F ₇ OCH ₃ , C ₄ F ₉ OCH ₃ , C ₄ F ₉ OC ₂ H ₅ , C ₇ F ₁₅ OC ₂ H _{5 and the} like can be mentioned. 1 type may be used independently and 2 or more types may be used together. The (fluoro) alkyl group of the hydrofluoroether may be linear or branched.
Specific examples of the tetraalkylsilane include silanes having an alkyl group having 1 to 5 carbon atoms, such as tetramethylsilane, trimethylethylsilane, trimethylisopropylsilane, and trimethyl-n-propylsilane. Is mentioned.

  Specific examples of the compound that generates gas upon thermal decomposition by heating include azodicarbonamide, N, N'-dinitrosopentamethylenetetramine, 4,4'-oxybis (benzenesulfonylhydrazide), and the like. It is done.

In the present invention, the method for producing the thermal expansion microcapsule (B) is not particularly limited, and for example, it can be produced by the method described in Japanese Patent No. 4386696.
Moreover, as said thermal expansion microcapsule (B), what is marketed as Matsumoto microsphere (trademark) F series made from Matsumoto Yushi Seiyaku Co., Ltd. can be used, Specifically, a super-high temperature expansion type | mold is used. F-170, F-190D and the like can be suitably used.

Moreover, in this invention, content of the said thermally expansible microcapsule (B) is 0.01-20 mass% with respect to the total mass of the foaming composition of this invention, 0.1-10 It is preferable that it is mass%.
When the content of the heat-expandable microcapsule (B) is in the above range, it has a high expansion ratio, and is excellent in physical properties such as tensile strength after foaming, tear strength, and compression set resistance.
This is because, with chemical foaming using azodicarbonamide (ADCA) or the like, bubbles cannot be retained in the foam, whereas when the thermally expandable microcapsule (B) is used, the foaming agent ( This is thought to be because bubbles can be held in the outer shell.

<Styrenic thermoplastic elastomer>
The foam composition of the present invention preferably contains a styrenic thermoplastic elastomer from the viewpoint of improving compression set.
As the styrenic thermoplastic elastomer, those described in paragraphs [0163] to [0168] of Patent Document 1 can be used.

<Filler>
The foam composition of the present invention preferably contains a filler from the viewpoint of improving the reinforcing property and workability.
As the filler, those described in paragraphs [0169] to [0180] of Patent Document 1 can be used.

The foam composition of the present invention is an anti-aging agent, an antioxidant, a pigment (dye), a plasticizer, a thixotropic agent, an ultraviolet absorber, as long as the purpose of the present invention is not impaired. Various additives such as a flame retardant, a solvent, a surfactant (including a leveling agent), a dispersant, a dehydrating agent, a rust preventive agent, an adhesion imparting agent, an antistatic agent, and a filler can be contained.
As the various additives, those described in paragraphs [0182] to [0210] of Patent Document 1 can be used.

Further, the foam composition of the present invention may include the above-mentioned thermoplastic elastomer (A) capable of self-crosslinking, but a vulcanizing agent, a vulcanization aid, and a vulcanization accelerator within a range not impairing the object of the present invention. Further, a vulcanization retarder or the like can be used in combination.
As the vulcanizing agent, those described in paragraphs [0211] and [0212] of Patent Document 1 can be used.

The production method of the foam (composition) of the present invention is not particularly limited. For example, the thermoplastic elastomer (A) and the thermal expansion microcapsule (B), and various additives that may be contained as necessary. And a method of foaming with a hot press or the like using a single screw extruder, a twin screw extruder or the like.
In the present invention, as shown in the examples described later, the mixing is performed by preliminarily mixing the thermal expansion microcapsule (B) and components other than the thermal expansion microcapsule (B). An embodiment in which is mixed is preferable. When mixing in this mode, a spreader (for example, paraffin oil or the like) is added to the pellets from the viewpoint of improving the dispersibility of the thermal expansion microcapsules (B) to be mixed later. Is preferred.

EXAMPLES Next, although an Example is shown and this invention is demonstrated more concretely, this invention is not limited to these.
(Examples 1 to 3 , Reference Example 4, Comparative Examples 1 to 3)
Of the components in parts by mass shown in Table 1 below, pellets made of a thermoplastic elastomer composition obtained by previously kneading all the components except the thermal expansion microcapsule (B) and the foaming agent (diameter 1.5 mm × length 3 mm) and the thermal expansion microcapsules (B) and the foaming agent of the mass parts (numbers in parentheses are mass%) shown in Table 1 below and kneading with a kneader at 120 ° C. for 5 minutes, and then a sheet (2 mm × 150 mm × 150 mm) and a Rupke (diameter 29 mm × thickness 12.5 mm) mold, and foamed to prepare a sheet-like foam and a Rupke-like foam.

  The specific gravity, expansion ratio, tensile properties, tear strength and compression set of the foam obtained by extrusion foaming were measured by the following methods. The results are shown in Table 1 below. The specific gravity and the expansion ratio were the same values for both the sheet-like foam and the Lupke-like foam.

<Specific gravity>
The specific gravity (g / cm ³ ) was measured using a fully automatic specific gravity measuring device.

<Foaming ratio>
The expansion ratio was calculated from the specific gravity before and after foaming and the ratio (specific gravity before foaming / specific gravity after foaming).

<Tensile properties>
A No. 3 dumbbell-shaped test piece was punched out from each of the prepared sheet-like foams, and a tensile test at a tensile speed of 500 mm / min was conducted according to JIS K6251: 2004. 50% modulus (M ₅₀ ) [MPa], 100 The% modulus (M ₁₀₀ ) [MPa] and the tensile strength (T _B ) [MPa] were measured at room temperature.

<Tear strength>
About each prepared sheet-like foam, tear strength (TrA) [MPa] was measured according to JISK6252: 2007.

<Compression set (C-Set)>
Each of the prepared Rupke-like foams was compressed by 25% with a dedicated jig, and the compression set after being left at 70 ° C. for 22 hours was measured according to JIS K6262: 2006.

The detail of each component of the said Table 1 is as follows.
Thermoplastic elastomer (A1): maleic anhydride modified polypropylene (Admer QE060, manufactured by Mitsui Chemicals)
Thermoplastic elastomer (A2): maleic anhydride modified ethylene-propylene copolymer (TX-1215, manufactured by Mitsui Chemicals)
Styrenic thermoplastic elastomer: Septon 4077 (SEEPS, styrene content: 30% by mass, manufactured by Kuraray Co., Ltd.)
-Tanac P (a compound capable of introducing a nitrogen-containing heterocycle): 1,3,5-tris (2-hydroxyethyl) isocyanuric acid (manufactured by Nissei Sangyo Co., Ltd.)
ATA (compound capable of introducing a nitrogen-containing heterocycle): 4H-3-amino-1,2,4-triazole (manufactured by Nippon Carbide)
Phenol-based anti-aging agent: 3- (4′-hydroxy-3 ′, 5′-di-tert-butylphenyl) propionic acid-n-octadecyl (AO-50, manufactured by ADEKA)
-Paraffin oil: Thumper 2280 (manufactured by Nippon Sun Oil Co., Ltd.)
Thermal expansion microcapsule (B1): F190D (outer shell thermoplastic resin: nitrile resin (softening point: 160 to 170 ° C.), outer shell blowing agent: n-pentane (boiling point: 36 ° C.), Matsumoto Oil (Manufactured by Pharmaceutical)
Foaming agent: azodicarbonamide (AZ VI-8, decomposition temperature: 200 ° C., manufactured by Otsuka Chemical Co., Ltd.)

As is apparent from Table 1 above, the composition of Comparative Example 2 prepared by blending azodicarbonamide that does not correspond to the thermally expanded microcapsule has a specific gravity slightly lower than that of the base composition of Comparative Example 1, but it is foamed. The magnification only improved to about 1.3 times. It was also found that the tensile properties and tear strength after foaming were lowered and the compression set was also increased.
In addition, the composition of Comparative Example 3 prepared by blending a large amount of thermally expanded microcapsules has a lower specific gravity than the composition of Comparative Example 2 and the foaming ratio is improved, but the tensile properties and tear strength after foaming are improved. Was further reduced, and the compression set was also increased.
On the other hand, the compositions of Examples 1 to 3 prepared by blending a predetermined amount of thermal expansion microcapsules have a lower specific gravity than the composition of Comparative Example 2, the foaming ratio is improved, and the composition of Comparative Example 2 It was found that the tensile properties and tear strength after foaming were higher than the composition, and the compression set was also lower.
In particular, the composition of Example 1 using polypropylene rubber as the elastomer constituting the main chain of the thermoplastic elastomer (A) has a higher expansion ratio than the composition of Example 3, and has tensile properties after foaming. Was found to be high.
In addition, the composition of Example 1 using 1,3,5-tris (2-hydroxyethyl) isocyanuric acid as a compound capable of introducing a nitrogen-containing heterocycle has the same expansion ratio as that of the composition of Reference Example 4. It was found that the tensile properties and tear strength after foaming were higher than those of the composition of Reference Example 4, and the compression set was also lower.

Claims (8)

A foam composition comprising a thermoplastic elastomer (A) having a side chain containing a nitrogen-containing heterocyclic ring and a carbonyl group, and a thermally expandable microcapsule (B),
The content of the thermal expandable microcapsule (B) is Ri 0.01 to 20% by mass relative to the total weight of the foaming composition,
The composition for foams whose said nitrogen-containing heterocyclic ring is isocyanuric acid .   The heat-expandable microcapsule (B) is composed of an outer shell made of a thermoplastic resin, and a foaming agent encapsulated in the outer shell and having a boiling point equal to or lower than the softening point of the thermoplastic resin. The foam composition according to claim 1, which is an expandable microsphere.   The foam composition according to claim 1 or 2, wherein the elastomer constituting the main chain of the thermoplastic elastomer (A) is polypropylene rubber.   The foam composition according to claim 2 or 3, wherein the thermoplastic resin forming the outer shell of the thermally expandable microcapsule (B) is a nitrile polymer. The composition for foams in any one of Claims 1-4 in which the side chain of the said thermoplastic elastomer (A) contains the structure represented by following formula (1).
(In the formula, A is a nitrogen- containing heterocycle , the nitrogen-containing heterocycle is isocyanuric acid, B is a single bond; oxygen atom, amino group NR ′ (R ′ is a hydrogen atom or an alkyl having 1 to 10 carbon atoms) Or a sulfur atom; or an organic group that may contain these atoms or groups.) The side chain containing the structure represented by the formula (1) contains a structure represented by the following formula (2) or (3) bonded to the main chain at the α-position or the β-position. Foam composition.
Wherein A is a nitrogen- containing heterocycle , the nitrogen-containing heterocycle is isocyanuric acid, B and D are each independently a single bond; an oxygen atom, an amino group NR ′ (R ′ is a hydrogen atom or a carbon number 1-10 alkyl groups) or a sulfur atom; or an organic group that may contain these atoms or groups.) The composition for foams according to any one of claims 1 to 6 , wherein at least a part of the thermoplastic elastomer (A) is cross-linked with each other via the nitrogen-containing heterocycle. Foam obtained by a foamed composition is foamed according to any one of claims 1-7.