JP2015078342A - Foamable composition and foam - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a foamable composition which can reduce the diameter of mixed bubbles and allows film thinning of the foam.SOLUTION: A foamable composition comprises an ethylene/α-olefin/nonconjugated diene copolymer, a surfactant, a crosslinking agent and a catalyst, and the surfactant is composed of a siloxane and/or a perfluoroalkyl structure bonded with a linear-alkyl and/or an aromatic alkyl structure. The blend ratio of the surfactant is 0.1-20 pts. mass to 100 pts. mass of the copolymer.

Description

  The present invention relates to a foamable composition comprising an ethylene / α-olefin / non-conjugated diene copolymer, a surfactant, a crosslinking agent, and a catalyst.

For example, in various fields such as construction, civil engineering, electricity, electronics, vehicles, etc., foams seal parts that need to be protected from gas or liquid, sealing materials that seal the peripheral part of the housing, and shocks and shocks. It is used as a cushioning material.
The foam is obtained by subjecting a resin composition mainly composed of an olefin resin and an elastomer to a foaming treatment. Examples of these foams include thermoplastic resin foams made of polyethylene resins, polypropylene resins, etc., rubber foams made of synthetic rubber or natural rubber, and the like.
When a foam is used as a sealing material or cushioning material, the compression flexibility of the foam, that is, the repulsive stress that the foam tries to recover from the compressed state depends on the material and usage conditions of the article in which the foam is used. Appropriately set appropriately and that the set repulsive stress and sealing performance can be maintained over the usable period of the article in which the foam is used.

In recent years, downsizing of devices has been remarkably advanced in the field of electronic devices. In a small electronic device having a display screen such as a mobile phone, it is desirable that the ratio of the screen size in the main surface of the housing is as large as possible. For this reason, the thickness required for the foam disposed between the screen panel and the housing (clearance) tends to be thinner and the width tends to be narrower.
As an example of a foam that can be placed under such a narrow clearance constraint, a technique has been proposed in which a foamable composition is foamed using an organic solvent as a foaming agent (see Patent Document 1). . This foam can be disposed even in a narrow clearance.
However, as described in Patent Document 1, when foaming a foamable composition using an organic solvent as a foaming agent, it is difficult to form small bubbles because the bubbles grow too much or break up. There's a problem. If small bubbles cannot be formed, it is difficult to produce a foam having a small foam thickness.
Conventionally, a mechanical floss method is widely known as a method for forming bubbles in a foam. For example, when foaming a urethane resin composition by the mechanical floss method, the interfacial tension of the urethane resin composition is reduced and the bubble diameter is reduced by blending a silicone-based foam stabilizer as described in Patent Document 2. Techniques are known. As a silicone type foam stabilizer for urethane, it is common to use polyether-modified silicone.
However, when ethylene / α-olefin / non-conjugated diene copolymer is used as the resin, the silicone-based foam stabilizer for urethane has poor compatibility with the copolymer, and it is difficult to reduce the interfacial tension. is there. Therefore, there is a problem that even if a silicone-based foam stabilizer for urethane is added to the copolymer, it is difficult to reduce the cell diameter and it is difficult to produce a foam having a small thickness.

JP 2011-213842 A JP 2005-227392 A

  The present invention has been made in view of the above-described conventional problems. When ethylene / α-olefin / non-conjugated diene copolymer is used as a resin, the thickness is reduced by reducing the diameter of mixed bubbles. It aims at providing the foamable composition which can manufacture a foam, and the foam manufactured using it.

As a result of intensive studies, the present inventors have found that the above problem can be solved by adding a specific surfactant having an interfacial tension reducing effect to the ethylene / α-olefin / non-conjugated diene copolymer, The present invention has been completed. The present invention includes the following contents.
(1) A foamable composition comprising an ethylene / α-olefin / non-conjugated diene copolymer, a surfactant, a crosslinking agent, and a catalyst, wherein the surfactant has a siloxane and / or perfluoroalkyl structure. A foamable composition in which a linear alkyl and / or aromatic alkyl structure is bonded.
(2) The foamable composition according to (1), wherein the amount of the surfactant is 0.1 to 20 parts by mass with respect to 100 parts by mass of the copolymer.
(3) The foamable composition according to the above (1) or (2), wherein the α-olefin is propylene and the non-conjugated diene is 5-vinyl-2-norbornene in the copolymer.
(4) The foamable composition according to any one of (1) to (3), wherein the crosslinking agent is a crosslinking agent having at least two SiH groups in one molecule.
(5) In any one of said (1)-(4) containing 3-15 mass parts of said crosslinking agents and 0.05-5.0 mass parts of said catalysts with respect to 100 mass parts of said copolymers. Foamable composition.
(6) The foamable composition according to any one of (1) to (5), further including an organic solvent having an SP value of 9 to 13.
(7) The foamable composition according to any one of (1) to (6), wherein the organic solvent is contained in an amount of 0.5 to 4.5 parts by mass with respect to 100 parts by mass of the copolymer.
(8) The foamable composition as described in any one of (1) to (7) above, which contains an organic solvent that is liquid at 23 ° C. as a foaming agent.
(9) The foamable composition according to any one of (1) to (8), wherein bubbles are mixed by a mechanical floss method.
(10) A foam formed by foaming and crosslinking the foamable composition according to any one of (1) to (9).

  According to the present invention, it is possible to provide a foamable composition capable of reducing the diameter of mixed bubbles and reducing the thickness of a foam by reducing the interfacial tension of an ethylene / α-olefin / nonconjugated diene copolymer. it can.

The distribution of the diameter of the bubble formed in the foamable composition in Example 21 is shown.

[Foaming composition]
The foamable composition according to the embodiment of the present invention is a foamable composition containing an ethylene / α-olefin / non-conjugated diene copolymer, a surfactant, a crosslinking agent, and a catalyst. The foamable composition foams and becomes a foam by being crosslinked.
Hereafter, each compound used for the foamable composition which concerns on embodiment of this invention is demonstrated in detail.

[Copolymer X]
The ethylene / α-olefin / non-conjugated diene copolymer (hereinafter referred to as Copolymer X) contained in the foamable composition is a block-like or randomized ethylene, α-olefin, and non-conjugated diene. Any of those copolymerized may be used, but a random copolymer is preferred. The copolymer X is usually crosslinked to form a foam resin.

<Α-olefin>
The α-olefin preferably has 3 to 20 carbon atoms.
Examples of the α-olefin include propylene, 1-butene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1- Tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-nonadecene, 1-eicocene, 9-methyl-1-decene, 11-methyl-1-dodecene, 12-ethyl-1-tetradecene, etc. Is mentioned. Of these, α-olefins having 3 to 10 carbon atoms are more preferable, and propylene, 1-butene, 1-hexene, and 1-octene are more preferably used. These α-olefins may be used alone or in combination of two or more. Among these, it is particularly preferable to use propylene.

<Non-conjugated dienes>
Examples of the non-conjugated diene include a chain non-conjugated diene, an alicyclic non-conjugated diene, and a norbornene derivative represented by the following general formula [I]. These may be used alone or in combination of two or more.

式［Ｉ］中、ｎは０ないし１０の整数であり、Ｒ^１は水素原子または炭素原子数１〜１０のアルキル基であり、Ｒ^２は水素原子または炭素原子数１〜５のアルキル基である。

In the formula [I], n is an integer of 0 to 10, R ¹ is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and R ² is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. is there.

  Specific examples of the chain non-conjugated diene include 1,4-hexadiene, 3-methyl-1,4-hexadiene, 4-methyl-1,4-hexadiene, 5-methyl-1,4-hexadiene, 4,5 -Dimethyl-1,4-hexadiene, 7-methyl-1,6-octadiene and the like.

  Specific examples of the cyclic non-conjugated diene include 5-methylene-2-norbornene, 1-methyl-5-methylene-2-norbornene, 1-ethyl-5-methylene-2-norbornene, 5-ethylidene-2-norbornene, Examples include 5-isopropylidene-2-norbornene, 5-vinylidene-2-norbornene, 6-chloromethyl-5-isopropenyl-2-norbornene, dicyclopentadiene, and methyltetrahydroindene.

  Specific examples of the norbornene derivative represented by the general formula [I] include 5-vinyl-2-norbornene, 5- (2-propenyl) -2-norbornene, 5- (3-butenyl) -2-norbornene, 5- (1-methyl-2-propenyl) -2-norbornene, 5- (4-pentenyl) -2-norbornene, 5- (1-methyl-3-butenyl) -2-norbornene, 5- (5-hexenyl)- 2-norbornene, 5- (1-methyl-4-pentenyl) -2-norbornene, 5- (2,3-dimethyl-3-butenyl) -2-norbornene, 5- (2-ethyl-3-butenyl)- 2-norbornene, 5- (6-heptenyl) -2-norbornene, 5- (3-methyl-5-hexenyl) -2-norbornene, 5- (3,4-dimethyl-4-pentenyl) -2 Norbornene, 5- (3-ethyl-4-pentenyl) -2-norbornene, 5- (7-octenyl) -2-norbornene, 5- (2-methyl-6-heptenyl) -2-norbornene, 5- (1 , 2-dimethyl-5-hexesyl) -2-norbornene, 5- (5-ethyl-5-hexenyl) -2-norbornene, 5- (1,2,3-trimethyl-4-pentenyl) -2-norbornene, etc. Is mentioned.

Among these, 5-vinyl-2-norbornene, 5- (2-propenyl) -2-norbornene, 5- (3-butenyl) -2-norbornene, 5- (4-pentenyl) -2-norbornene, 5 -(5-hexenyl) -2-norbornene, 5- (6-heptenyl) -2-norbornene, and 5- (7-octenyl) -2-norbornene are preferred. These norbornene compounds can be used alone or in combination of two or more. Further, among the above compounds, it is particularly preferable to use 5-vinyl-2-norbornene.
The copolymer X is preferably a copolymer of ethylene, propylene, and a norbornene derivative.

  Examples of the non-conjugated diene constituting the copolymer X include chain-type non-conjugated dienes, alicyclic non-conjugated dienes, and norbornene derivatives represented by the general formula [I], as well as 2,3-diisopropylidene. Non-conjugated polyenes such as triene such as -5-norbornene, 2-ethylidene-3-isopropylidene-5-norbornene, 2-propenyl-2,2-norbornadiene may be used. These can also be used with the non-conjugated dienes described above.

The blending amount of ethylene in the copolymer X is preferably 20 to 80 parts by mass, more preferably 30 to 70 parts by mass with respect to 100 parts by mass of the copolymer X as a monomer. The blending amount of the α-olefin in the copolymer X is preferably 20 to 60 parts by mass, and more preferably 30 to 50 parts by mass with respect to 100 parts by mass of the copolymer X as a monomer. Moreover, it is preferable that the compounding quantity of the nonconjugated diene in the copolymer X is 2-30 mass parts with respect to 100 mass parts of copolymers X as a monomer, and it is more preferable that it is 3-20 mass parts.
The number average molecular weight of the copolymer X is not particularly limited, but is preferably 600 to 5000, more preferably 900 to 3200. In addition, the number average molecular weight here is measured by polystyrene conversion using gel permeation chromatograph.

<Surfactant>
The surfactant in the present invention is a surfactant in which a linear alkyl and / or aromatic alkyl structure is bonded to a siloxane and / or perfluoroalkyl structure. By having this structure, the interfacial tension of the copolymer X can be sufficiently reduced, and the bubbles formed in the foam can be reduced in diameter. In the present specification, the straight-chain alkyl means a straight-chain alkyl having 3 or more carbon atoms.
From the viewpoint of reducing the bubble diameter, the linear alkyl and / or aromatic alkyl structure is preferably a linear alkyl structure, more preferably a linear alkyl structure having 4 to 16 carbon atoms, and still more preferably 6 carbon atoms. It is a linear alkyl structure of -14.

Among the above surfactants, the surfactant in which a linear alkyl and / or aromatic alkyl structure is bonded to a siloxane structure is a polydimethylsiloxane, and the side chain or terminal of the polydimethylsiloxane is One in which one or two or more are modified with a linear alkyl group and / or an aromatic alkyl group is preferable, and one in which a side chain in polydimethylsiloxane is modified with a linear alkyl group is more preferable.
Here, the linear alkyl group is preferably a linear alkyl group having 4 to 16 carbon atoms, and more preferably a linear alkyl group having 6 to 14 carbon atoms.
The aromatic alkyl group is preferably an aromatic alkyl group having about 7 to 14 carbon atoms such as a benzyl group, a phenylethyl group, or a phenylpropyl group, more preferably a phenylpropyl group, and particularly a 2-phenylpropyl group. Is more preferable.
Such kinematic viscosity siloxane structure in linear alkyl and / or aromatic surfactant alkyl structure is bonded is preferably ^{10~3000mm 2 / s, 20~1300mm 2 /} s is more preferable. In addition, kinematic viscosity here is measured at 25 degreeC using the Ubbelohde viscometer.

Among the above surfactants, those in which a linear alkyl and / or aromatic alkyl structure is bonded to a perfluoroalkyl structure, the perfluoroalkyl structure is a perfluoroalkane, and a side chain in the perfluoroalkane or Those in which one or more of the terminals are modified with a linear alkyl group and / or an aromatic alkyl group are preferred, and those in which the side chain in the perfluoroalkane is modified with a linear alkyl group are more preferred.
Here, the linear alkyl group is preferably a linear alkyl group having 4 to 16 carbon atoms, and more preferably a linear alkyl group having 6 to 14 carbon atoms.
The aromatic alkyl group is preferably an aromatic alkyl group having about 7 to 14 carbon atoms such as a benzyl group, a phenylethyl group, or a phenylpropyl group, more preferably a phenylpropyl group, and particularly a 2-phenylpropyl group. Is more preferable.
As a perfluoroalkane, a C4-C12 thing is preferable and a C6-C10 is more preferable. The perfluoroalkane is preferably linear.

<Surfactant content>
The foamable composition of the present invention preferably contains 0.1 to 20 parts by mass of a surfactant with respect to 100 parts by mass of the copolymer X. By setting the content of the surfactant to 0.1 parts by mass or more with respect to 100 parts by mass of the copolymer X, small-sized fine bubbles can be formed. Moreover, since it can prevent the fall of the viscosity of a foamable composition by making it 20 mass parts or less and can raise the retention power of a bubble, it becomes easy to hold | maintain the fine bubble formed in the composition.
From the viewpoint of obtaining small-diameter bubbles, the content of the surfactant is more preferably 0.3 to 10 parts by mass and further preferably 0.5 to 5 parts by mass with respect to 100 parts by mass of the copolymer X.

<Crosslinking agent>
As a cross-linking agent contained in the foamable composition, a compound that crosslinks the copolymer X by advancing the hydrosilylation reaction by heating or the like and that is compatible or has good dispersibility with the copolymer X is used. Is possible.
For example, when the non-conjugated diene component of the copolymer X is a norbornene derivative represented by the above general formula [I], it is preferable to use a siloxane compound having a plurality of SiH groups in one molecule. . That is, the resin constituting the foam is preferably a resin obtained by crosslinking the copolymer X with a siloxane compound having a plurality of SiH groups in one molecule. The siloxane compound having a plurality of SiH groups in one molecule is more preferably a siloxane compound having 2 or 3 SiH groups in one molecule, and a siloxane compound having two SiH groups in one molecule. Is more preferable.
Examples of the siloxane compound having two SiH groups in one molecule include the SiH group-containing compound (1) represented by the following general formula [II].

式［ＩＩ］中、Ｒ^３は炭素数１〜１０の一価の基で、非置換あるいは置換の飽和炭化水素基または芳香族炭化水素基であり、１分子内で同種でも異種でもよく、ａは０〜２０の整数であり、ｂは０〜２０の整数であり、Ｒ^４は炭素数１〜３０の二価の有機基または酸素原子である。

In the formula [II], R ³ is a monovalent group having 1 to 10 carbon atoms and is an unsubstituted or substituted saturated hydrocarbon group or aromatic hydrocarbon group, which may be the same or different in one molecule, Is an integer of 0 to 20, b is an integer of 0 to 20, and R ⁴ is a divalent organic group having 1 to 30 carbon atoms or an oxygen atom.

The SiH group-containing compound (1) having two SiH groups in one molecule represented by the above general formula [II] has SiH groups at both ends of the molecule, and has two SiH groups per molecule. In the general formula [II], specific examples of R ³ are methyl group, ethyl group, propyl group, isopropyl group, butyl group, amyl group, cyclopentyl group, hexyl group, cyclohexyl group, octyl group, chloromethyl group, 2- Examples include chloroethyl group, 3-chloropropyl group, phenyl group, phenylmethyl group, 2-phenylethyl group, 2-phenylpropyl group and the like. A methyl group, an ethyl group, and a phenyl group are preferable, and a methyl group is more preferable among them. R ⁴ is preferably a divalent organic group represented by the following formula.

なお、上記式において、Ｒ^４１は、炭素数１〜１０の一価の基であり、その具体例は、上記Ｒ^３の具体例として列挙したものと同様であるが、フェニル基が好ましい。

In the above formula, R ⁴¹ is a monovalent group having 1 to 10 carbon atoms, and specific examples thereof are the same as those listed as specific examples of R ³ above, but a phenyl group is preferable.

Preferably, both a and b are 10 or less, more preferably 5 or less, particularly preferably 2 or less, and most preferably a and b are equally 2 or less.
Preferable examples of the SiH group-containing compound (1) having two SiH groups in one molecule described above include siloxane compounds represented by the following formula.

式［ＩＩＩ］中、Ｒ^５は炭素数１〜１０の一価の基で、非置換あるいは置換の飽和炭化水素基または芳香族炭化水素基であり、１分子内で同種でも異種でもよく、ａ、ｂ及びｃはそれぞれ独立に０〜２０の整数であり、Ｒ^６は炭素数１〜３０の三価の有機基である。
一般式［ＩＩＩ］中、Ｒ^５の具体例は、上記Ｒ^３の具体例として列挙したものと同様であるが、好ましくは、メチル基、エチル基、およびフェニル基であり、中でもメチル基がより好ましい。また、好ましくは、ａ、ｂ、ｃいずれも１０以下、より好ましくは５以下、特に好ましくは２以下であり、最も好ましくはａ、ｂ、ｃがいずれも等しく２以下である。
また、Ｒ^６は、以下の式で表される三価の有機基であることが好ましい。 Examples of the siloxane compound having three SiH groups in one molecule include the SiH group-containing compound (2) represented by the following general formula [III].

In the formula [III], R ⁵ is a monovalent group having 1 to 10 carbon atoms, and is an unsubstituted or substituted saturated hydrocarbon group or aromatic hydrocarbon group, which may be the same or different in one molecule, , B and c are each independently an integer of 0 to 20, and R ⁶ is a trivalent organic group having 1 to 30 carbon atoms.
In general formula [III], specific examples of R ⁵ are the same as those listed as specific examples of R ³ above, but are preferably a methyl group, an ethyl group, and a phenyl group, and more preferably a methyl group. preferable. Preferably, all of a, b and c are 10 or less, more preferably 5 or less, particularly preferably 2 or less, and most preferably a, b and c are all equally 2 or less.
R ⁶ is preferably a trivalent organic group represented by the following formula.

なお、上記式において、Ｒ^６１は、炭素数１〜１０の一価の基であり、その具体例は、上記Ｒ^３の具体例として列挙したものと同様であるが、フェニル基が好ましい。

In the above formula, R ⁶¹ is a monovalent group having 1 to 10 carbon atoms, and specific examples thereof are the same as those listed as specific examples of R ³ above, but a phenyl group is preferable.

Moreover, as a preferable example of the SiH group-containing compound (2) having three SiH groups in one molecule described above, a siloxane compound represented by the following formula can be given.

  It is preferable that the compounding quantity of the crosslinking agent in the foamable composition of the copolymer X is 3-25 mass parts with respect to 100 mass parts of the copolymer X, It is more preferable that it is 5-20 mass parts. More preferably, it is -15 mass parts. If the blending amount of the crosslinking agent is within this range, even when the foaming agent is blended, the foaming agent foams well, and a predetermined void ratio and continuous void ratio can be formed.

<Catalyst>
As a catalyst, the catalyst which advances the crosslinking reaction which bridge | crosslinks the copolymer X with the said crosslinking agent can be used. For example, if the crosslinking agent is a siloxane compound, it is not limited as long as it is used as a catalyst for hydrosilylation reaction. For example, chloroplatinic acid, platinum olefin complex, platinum vinylsiloxane complex, platinum black, platinum triphenylphosphine Examples thereof include platinum catalysts such as complexes, platinum carbonyl complexes, and platinum acetyl acetate, palladium catalysts, and rhodium catalysts.
The platinum catalyst is preferably a 3% Pt-CTS-CTS solution, Pt / 1,3,5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasiloxane complex, and 1,3,3. It is preferable to use a mixture of 5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasiloxane.
It is preferable that the compounding quantity of the catalyst in resin of the copolymer X is 0.05-5.0 mass part with respect to 100 mass parts of copolymer X, and is 0.05-1.0 mass part. More preferably, it is 0.1-0.5 mass part. If the blending amount of the catalyst is within this range, the porous body can be cured at a speed capable of forming.

<Organic solvent>
The foamable composition of the present invention preferably contains an organic solvent having an SP value (solubility parameter) of 9 to 13. Moreover, it is preferable to contain the organic solvent of SP values 9-13 when a foamable composition is foamed by the mechanical floss method mentioned later.
The SP value of each solvent is indicated by δ _s , for example, on pages 595 to 598 of “Polymer Data Handbook” -Basic Edition- (Edited by Polymer Society, January 30, 1986, first edition). it is known as a value obtained in a manner similar to [delta] _s.

As apparent from the fact that the SP value of the dimethylpolysiloxane structure is 7.3, for example, the surfactant has a relatively low SP value of the siloxane and / or perfluoroalkyl structure. On the other hand, as is apparent from the fact that the SP value of the polyethylene component is 7.9, the copolymer X is usually higher than the surfactant although the SP value is relatively low.
Therefore, the organic solvent having a relatively high SP value of about 9 to 13 as described above can be dispersed in the copolymer X while not having high compatibility with the surfactant.
Further, in the surfactant, for example, when comparing a dimethylpolysiloxane structure part and an alkyl structure part, the dimethylpolysiloxane structure part has a larger SP value difference from the organic solvent. Therefore, as will be described later, in the foamable composition, for example, when foamed by a mechanical floss method, it is estimated that the dimethylpolysiloxane structure in the surfactant is densely arranged around the bubbles. In the surfactant, when many dimethylpolysiloxane structures are arranged around the bubbles, the surface tension of the bubbles is lowered. Therefore, it is presumed that the internal pressure of the bubbles is reduced, the bubbles are dissolved in the copolymer X and the like, and the bubbles are not easily lost, and the bubble diameter is reduced.
The SP value of the organic solvent is preferably 10 to 13 from the viewpoint of making bubbles more difficult to disappear and making it easier to reduce the diameter of the bubbles.

Examples of the organic solvent having an SP value of 9 to 13 include ethyl acetate, methyl ethyl ketone, isopropyl alcohol, ethanol, and the like. Among these, isopropyl alcohol is preferable. In particular, isopropyl alcohol is easy to uniformly disperse in the copolymer X, but is not highly compatible with the surfactant, and thus easily exhibits the above-described effects.
In the foamable composition, the organic solvent having an SP value of 9 to 13 is contained, for example, in an amount of about 0.5 to 10 parts by weight, preferably 0.5 to 4.5 parts by weight, based on 100 parts by weight of the copolymer X. Parts, more preferably 1.5 to 3.5 parts by mass.
An organic solvent becomes easy to disperse | distribute uniformly in a foamable composition because content becomes below the said upper limit. Moreover, the effect by adding the organic solvent becomes easy to be exhibited by making it more than the said lower limit. Although the organic solvent of SP value 9-13 may be used individually by 1 type, you may use 2 or more types together.
The SP values of typical solvents and resins are shown in Table 1 below.

<Other additives>
(Reaction inhibitor)
The foamable composition of the present invention may contain a reaction inhibitor. Reaction inhibitors include benzotriazole, ethynyl group-containing alcohols such as ethynylcyclohexanol, acrylonitrile, N, N-diallylacetamide, N, N-diallylbenzamide, N, N, N ′, N′-tetraallyl-o Amide compounds such as phthalic acid diamide, N, N, N ′, N′-tetraallyl-m-phthalic acid diamide, N, N, N ′, N′-tetraallyl-p-phthalic acid diamide, sulfur, phosphorus, nitrogen And organic peroxides such as amine compounds, sulfur compounds, phosphorus compounds, tin, tin compounds, tetramethyltetravinylcyclotetrasiloxane and hydroperoxide.
The reaction inhibitor is 0.01 to 50 parts by weight, preferably 0.01 to 30 parts by weight, based on 100 parts by weight of the total of the copolymer X and other resin components contained in the foamable composition. More preferably 0.01 to 20 parts by weight, still more preferably 0.01 to 10 parts by weight, particularly preferably 0.05 to 5 parts by weight. When the content of the reaction inhibitor is 0.01 parts by weight or more, the speed of the crosslinking reaction can be suppressed, and the reaction can be easily controlled. If it is 50 parts by weight or less, the production cost can be suppressed without excessively suppressing the speed of the crosslinking reaction.

(Inorganic filler)
The foamable composition of the present invention may contain an inorganic filler. Specific examples of the inorganic filler include light calcium carbonate, heavy calcium carbonate, talc, and clay. Although the kind and compounding quantity of these inorganic fillers can be suitably selected according to the use, the content of the inorganic filler is 400 parts by weight or less, preferably 1 to 300 parts by weight with respect to 100 parts by weight of the copolymer X. It is. It is preferable that the content of the inorganic filler is appropriately determined according to the required physical properties.

Moreover, you may mix | blend additives other than said reaction inhibitor and an inorganic filler with a foamable composition. Furthermore, the foamable composition may contain other resin components other than the copolymer X as long as the object of the present invention is not impaired.
Furthermore, the foamable composition of the present invention is preferably mixed with bubbles by a mechanical froth method as described later, but may be foamed by a method other than the mechanical floss method. For example, the foamable composition may contain a foaming agent composed of an organic solvent, etc., and the foamable composition may be heated to vaporize the foaming agent. Examples of the organic solvent used as the foaming agent include a low-boiling component that is liquid at 23 ° C. and volatilizes when heated in the step (2) described later to foam the foamable composition. Specific examples of the blowing agent include, for example, chain or cyclic hydrocarbons such as butane, pentane, hexane, octane, nonane, decane, undecane, cyclopentane, and cyclohexane, ketones such as cyclopentanone, cyclohexanone, and methyl ethyl ketone, Esters such as ethyl acetate and butyl acetate, ethers such as tetrahydrofuran, aromatics such as benzene, toluene, xylene, and ethylbenzene, nitrogen-containing compounds such as acetonitrile and NN dimethylformamide, methylene chloride, chloroform, and chlorofluorocarbon And halogens. These foaming agents may be used independently and 2 or more types may be used together. Among these, it is preferable to use a solvent having a boiling point of 150 ° C. or less, and methyl ethyl ketone, normal hexane, toluene, and xylene are particularly preferable.
As will be described later, a method of foaming with a foaming agent and a mechanical froth method may be used in combination. However, when the foamable composition contains an organic solvent having an SP value of 9 to 13, the organic solvent is foamed. It may be used as an agent. Moreover, you may use together the organic solvent of SP value 9-13, and organic solvents other than SP value 9-13.

[Foam]
The foam according to the present invention is obtained by foaming and crosslinking the above foamable composition, and is a porous body of a resin obtained by crosslinking the copolymer X. Moreover, a foam is although it does not specifically limit, For example, it is used as a sealing material and a buffer material of an electronic device, and it is preferable that it is a sheet form.
The foam preferably has a void ratio of 50 to 95 vol%, a strength at 50% compression of 300 kPa or less, and a compression set of 20% or less in an atmosphere at a temperature of 80 ° C. and a relative humidity of 90%.
The 50% compression strength and compression set are values measured in accordance with JIS K6767.

[Properties of porous material]
<Thickness of porous body>
Although the thickness of a foam is not specifically limited, It is preferable that they are 50 micrometers-2 mm, and it is more preferable that they are 100 micrometers-1 mm. If the thickness of the foam is 50 μm or more, the required mechanical strength can be ensured. Moreover, if the thickness of a foam is 2 mm or less, a softness | flexibility is favorable.

<Average bubble diameter>
The average cell diameter of the foam is preferably 1 to 200 μm, more preferably 10 to 50 μm. When the average cell diameter is within the above range, the required flexibility is obtained and the thickness accuracy is improved during film formation. Here, the “average bubble diameter” means the average value of the diameters of 50 arbitrary bubbles by observing the cross section of the foam with a scanning electron microscope (manufactured by Hitachi High-Technology Co., Ltd., model number “S-3400N”). It is.

<Magnification>
The foaming ratio of the foam is preferably 1.1 to 15 times, more preferably 1.5 to 10 times, and further preferably 1.5 to 5 times, from the viewpoint of improving the impact absorbing performance. The expansion ratio refers to a value calculated by measuring a specific volume before foaming and after foaming (unit: cc / g) and calculating a specific volume after foaming / a specific volume before foaming.

[Method for producing foam]
The method for producing a foam according to the present invention includes a step (1) of obtaining a foamable composition comprising a copolymer X, a surfactant, a crosslinking agent, and a catalyst, and the foamable composition can be crosslinked. Heating to a suitable temperature to crosslink the foamable composition (2).

(Process (1))
In the step (1), it is preferable that bubbles are mixed into the foamable composition by a mechanical floss method. However, you may mix | blend the foaming agent which consists of the organic solvent etc. which were mentioned above with a foamable composition. When blending a foaming agent, the foam is foamed by heating in step (2) described below.
When foaming with a foaming agent, it may be used in combination with the mechanical floss method or may be used alone without being used in combination.
When the mechanical froth method is used, in the step (1), the copolymer X, the surfactant, the crosslinking agent, the catalyst, and optional components to be blended as necessary are Banbury mixer, pressure kneader, etc. A foamable composition in which bubbles are formed by kneading while injecting gas with a kneading machine is obtained. Nitrogen, air, carbon dioxide, argon or the like can be used as the gas.
The foamable composition is then preferably processed into a sheet by being continuously conveyed while kneading using a calendar, an extruder, a conveyor belt casting, or the like.

(Process (2))
In step (2), the foamable composition preferably processed into a sheet is heated to crosslink the foamable composition to obtain a foam. At this time, as heating temperature, 70-145 degreeC is preferable and 90-115 degreeC is more preferable.
The manufacturing method of a foam may have the process of extending | stretching a foam. The step of stretching the foam may be performed while being heated in the step of heating after being processed into a sheet shape.
The foaming treatment method is not limited to the above, and various known methods can be used including the method described in the plastic foam handbook (Makihiro, Atsushi Kosaka, published by Nikkan Kogyo Shimbun, 1973).

Examples The present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.
[Evaluation method]
The foamable composition was taken as a preparation, and the average value of the observed bubble diameters was measured to evaluate the average bubble diameter.
In addition, about Examples 1-18 and Comparative Examples 1-2, the obtained foamable composition was taken to a preparation, and it observed with an optical microscope (the Keyence Corporation make, VHX-2000) 1 minute later (observation magnification 400) The average value of the diameters of 100 observed arbitrary bubbles was measured, and the average bubble diameter was calculated. Moreover, about Examples 19-23 and Reference Example 1, the obtained foamable composition was taken in a preparation, and after 1 minute, observed with an optical microscope (manufactured by Keyence Corporation, VHX-2000) (observation magnification 400 times, The observation area was 0.5 mm ² ). And the average value of the diameter of all the observed bubbles was measured, and the average bubble diameter was computed.

[Examples 1-7, Comparative Examples 1-2]
<Example 1>
According to the formulation shown in Table 2, copolymer A, surfactant, cross-linking agent and catalyst were mixed and nitrogen gas was injected while stirring a high-viscosity fluid agitator (product name “VIBRO”, manufactured by Chilling Industries Co., Ltd. PQLABO ") was stirred at a rotation speed of 500 rpm and a sample flow rate of 2000 mL / min, and mixed with bubbles to obtain a foamable composition for evaluation.
The properties of the obtained foamable composition for evaluation were evaluated by the method described above. The results are shown in Table 4.
<Example 2>
A foamable composition was obtained in the same manner as in Example 1 except that the surfactant B was used instead of the surfactant A. The properties of the obtained foamable composition were evaluated by the methods described above. The results are shown in Table 4.
<Example 3>
Instead of copolymer A, copolymer B was used. Moreover, the foamable composition was obtained like Example 2 except the compounding quantity of the crosslinking agent having been 7 mass parts. The properties of the obtained foamable composition were evaluated by the methods described above. The results are shown in Table 4.
<Example 4>
A foamable composition was obtained in the same manner as in Example 1 except that the surfactant C was used instead of the surfactant A. The properties of the obtained foamable composition were evaluated by the methods described above. The results are shown in Table 4.
<Example 5>
A foamable composition was obtained in the same manner as in Example 1 except that the surfactant D was used instead of the surfactant A. The properties of the obtained foamable composition were evaluated by the methods described above. The results are shown in Table 4.
<Example 6>
A foamable composition was obtained in the same manner as in Example 1 except that the surfactant E was used instead of the surfactant A. The properties of the obtained foamable composition were evaluated by the methods described above. The results are shown in Table 4.
<Example 7>
A foamable composition was obtained in the same manner as in Example 1 except that the surfactant F was used instead of the surfactant A. The properties of the obtained foamable composition were evaluated by the methods described above. The results are shown in Table 4.

<Comparative Example 1>
A foamable composition was obtained in the same manner as in Example 1 except that the surfactant G was used instead of the surfactant A. The properties of the obtained foamable composition were evaluated by the methods described above. The results are shown in Table 4.
<Comparative Example 2>
A foamable composition was obtained in the same manner as in Example 1 except that the surfactant H was used instead of the surfactant A. The properties of the obtained foamable composition were evaluated by the methods described above. The results are shown in Table 4.

* 1: Ethylene / propylene / 5-vinyl-2-norbornene random copolymer, “PX-068” manufactured by Mitsui Chemicals, Inc., number average molecular weight 920, ethylene content 50 mass%, diene content 11 mass%, 25 Complex viscosity at ℃ 10 Pa · s (1 rpm), SP value 7.17
* 2: Ethylene / propylene / 5-vinyl-2-norbornene random copolymer, “PX-062” manufactured by Mitsui Chemicals, Inc., number average molecular weight 3160, ethylene content 52.7 mass%, diene content 4.7 Mass%, complex viscosity at 25 ° C. 830 Pa · s (1 rpm), SP value 7.14
* 3: Surfactant A: one of side chains of dimethylpolysiloxane modified with linear alkyl having 6 carbon atoms, kinematic viscosity: 200 mm ² / s
* 4: Surfactant B: One of the side chains of dimethylpolysiloxane modified with linear alkyl having 14 carbon atoms, kinematic viscosity: 1000 mm ² / s
* 5: Surfactant C: One of the side chains of linear perfluorooctane modified with linear alkyl having 14 carbon atoms, kinematic viscosity: 1000 mm ² / s
* 6: Surfactant D: One of side chains of dimethylpolysiloxane modified with linear alkyl having 4 carbon atoms, kinematic viscosity: 30 mm ² / s
* 7: Surfactant E; one of the side chains of dimethylpolysiloxane modified with linear alkyl having 16 carbon atoms, kinematic viscosity: 1000 mm ² / s
* 8: Surfactant F; one in which one side chain of dimethylpolysiloxane is modified with 2-propylphenyl group, kinematic viscosity: 1300 mm ² / s
* 9: Surfactant G: One of the side chains of dimethylpolysiloxane modified with a polyether group of (EO) ₆ (PO) ₆ CH ₂ CH ₃ , kinematic viscosity: 200 mm ² / s
* 10: Surfactant H: One of the side chains of dimethylpolysiloxane modified with a polyether group of (EO) ₆ (PO) ₆ (CH ₂ ) ₁₀ CH ₃ , kinematic viscosity: 1200 mm ² / s
* 11: Siloxane crosslinking agent (SiH group-containing compound represented by the following formula, manufactured by Shin-Etsu Chemical Co., Ltd.)

  * 12: Platinum catalyst (3% Pt-CTS-CTS solution, Pt / 1,3,5,7-tetravinyl-1,3,5,7, -tetramethylcyclotetrasiloxane complex and 1,3,5, 7-tetravinyl-1,3,5,7-tetramethylcyclotetrasiloxane mixture, manufactured by NEM Chemcat)

[Examples 8 to 18]
<Example 8>
According to the formulation shown in Table 3, the copolymer A, the surfactant B, the cross-linking agent and the catalyst were mixed, and while injecting nitrogen gas, a high-viscosity fluid agitator (product name “ VIBRO PQLABO ”) was stirred at a rotational speed of 500 rpm and a sample flow rate of 2000 mL / min, and mixed with bubbles to obtain a foamable composition for evaluation.
The properties of the obtained foamable composition for evaluation were evaluated by the method described above. The results are shown in Table 4.
<Example 9>
A foamable composition was obtained in the same manner as in Example 8 except that the amount of surfactant B was 0.2 parts by mass. The properties of the obtained foamable composition were evaluated by the methods described above. The results are shown in Table 4.
<Example 10>
A foamable composition was obtained in the same manner as in Example 8, except that the amount of surfactant B was 0.3 parts by mass. The properties of the obtained foamable composition were evaluated by the methods described above. The results are shown in Table 4.
<Example 11>
A foamable composition was obtained in the same manner as in Example 8 except that the amount of surfactant B was 0.4 parts by mass. The properties of the obtained foamable composition were evaluated by the methods described above. The results are shown in Table 4.
<Example 12>
A foamable composition was obtained in the same manner as in Example 8 except that the amount of surfactant B was 0.5 parts by mass. The properties of the obtained foamable composition were evaluated by the methods described above. The results are shown in Table 4.
<Example 13>
A foamable composition was obtained in the same manner as in Example 8 except that the amount of surfactant B was 5 parts by mass. The properties of the obtained foamable composition were evaluated by the methods described above. The results are shown in Table 4.
<Example 14>
Instead of copolymer A, copolymer B was used. A foamable composition was obtained in the same manner as in Example 13 except that the amount of the crosslinking agent was 7 parts by mass. The properties of the obtained foamable composition were evaluated by the methods described above. The results are shown in Table 4.
<Example 15>
A foamable composition was obtained in the same manner as in Example 8, except that the amount of surfactant B was 6 parts by mass. The properties of the obtained foamable composition were evaluated by the methods described above. The results are shown in Table 4.
<Example 16>
A foamable composition was obtained in the same manner as in Example 8 except that the amount of surfactant B was 10 parts by mass. The properties of the obtained foamable composition were evaluated by the methods described above. The results are shown in Table 4.
<Example 17>
A foamable composition was obtained in the same manner as in Example 8 except that the amount of surfactant B was 11 parts by mass. The properties of the obtained foamable composition were evaluated by the methods described above. The results are shown in Table 4.
<Example 18>
A foamable composition was obtained in the same manner as in Example 8 except that the amount of surfactant B was 20 parts by mass. The properties of the obtained foamable composition were evaluated by the methods described above. The results are shown in Table 4.

[Evaluation results]

  As is apparent from Examples 1 to 18 above, the copolymer includes a copolymer, a surfactant, a crosslinking agent, and a catalyst, and the surfactant has a siloxane and / or perfluoroalkyl structure, linear alkyl and / or Alternatively, bubbles having a small average cell diameter could be formed in the foam by foaming a foamable composition having an aromatic alkyl structure bonded thereto. On the other hand, in Comparative Examples 1 and 2, since the surfactant was not a siloxane structure bonded with a linear alkyl and / or aromatic alkyl structure, the average bubble diameter of the bubbles should be made sufficiently small. I could not.

[Example 19]
According to the formulation shown in Table 5, copolymer A, surfactant, cross-linking agent and catalyst were mixed, and air was injected while homogenizer (manufactured by IKA, model: T18) was rotated at 10,000 rpm and sample amount 20 ml. The foamed composition for evaluation was prepared by stirring for 120 seconds and mixing the bubbles.
[Examples 20 to 23, Reference Example 1]
As shown in Table 5, isopropyl alcohol was further added to copolymer A, surfactant, crosslinking agent and catalyst in the amounts shown in Table 5, and then stirred while injecting air in the same manner as in Example 19. Then, the foamed composition for evaluation was obtained by mixing the bubbles.

  While evaluating the property of the foamable composition for evaluation obtained in Examples 19 to 23 and Reference Example 1, the ratio of bubbles of 40 μm or less was calculated. The evaluation results are shown in Table 6. Moreover, about Example 21, the bubble distribution for every 10 micrometers is shown in FIG. The number of bubbles in Example 21 when observed by the above evaluation method was 292.

＊１３：界面活性剤Ｉ；ジメチルポリシロキサンの側鎖の一つが炭素数６〜１４の直鎖アルキルにより変性されたもの、動粘度：１０００ｍｍ^２／ｓ

* 13: Surfactant I: One of the side chains of dimethylpolysiloxane modified with linear alkyl having 6 to 14 carbon atoms, kinematic viscosity: 1000 mm ² / s

  As is clear from the above results, in Examples 20 to 23, by adding isopropyl alcohol, the average cell diameter could be made smaller than in Example 19 in which isopropyl alcohol was not added. Also, by blending isopropyl alcohol, it is possible to form bubbles of 40 μm or less at a high ratio, and when obtaining a thin sheet-like foam from a foamable composition, for example, it is preferable to reduce foaming bubbles. It becomes possible to. In Example 19, the reason why the average bubble diameter was relatively larger than those in Examples 1 to 18 was presumed to be due to the difference in the stirring method. Further, in Reference Example 1 in which 5 parts by mass of isopropyl alcohol was blended, the compatibility in the foamable composition was lowered and uniform bubbles could not be obtained.

Claims (10)

  A foamable composition comprising an ethylene / α-olefin / non-conjugated diene copolymer, a surfactant, a crosslinking agent, and a catalyst, wherein the surfactant is linear in a siloxane and / or perfluoroalkyl structure. A foamable composition having an alkyl and / or aromatic alkyl structure bonded thereto.   The foamable composition according to claim 1, wherein the amount of the surfactant is 0.1 to 20 parts by mass with respect to 100 parts by mass of the copolymer.   The foamable composition according to claim 1 or 2, wherein in the copolymer, the α-olefin is propylene and the non-conjugated diene is 5-vinyl-2-norbornene.   The foamable composition according to any one of claims 1 to 3, wherein the crosslinking agent is a crosslinking agent having at least two SiH groups in one molecule.   The foamable composition according to any one of claims 1 to 4, comprising 3 to 15 parts by mass of the crosslinking agent and 0.05 to 5.0 parts by mass of the catalyst with respect to 100 parts by mass of the copolymer.   The foamable composition according to any one of claims 1 to 5, further comprising an organic solvent having an SP value of 9 to 13.   The foamable composition according to any one of claims 1 to 6, wherein the organic solvent is contained in an amount of 0.5 to 4.5 parts by mass with respect to 100 parts by mass of the copolymer.   The foamable composition according to any one of claims 1 to 7, comprising an organic solvent which is liquid at 23 ° C as a foaming agent.   The foamable composition according to claim 1, wherein bubbles are mixed by a mechanical floss method.   The foam formed by foaming the foamable composition in any one of Claims 1-9, and bridge | crosslinking.

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