JP2011208118A - Elastomer composition foam and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce an elastomer composition foam having fine foamed cells simply and in large quantities.SOLUTION: A mixture is formed by melt-mixing 10-90 pts.wt. of an elastomer (A) and 10-90 pts.wt. of a thermoplastic resin (B), wherein the sum of (A) and (B) is 100 pts.wt. The mixture is crosslinked and foamed to obtain foamed cells having an average cell diameter measured with a scanning electron microscope (SEM) of 50-3,000 nm. The elastomer composition foam contains the foamed cells, wherein the percentage of the foamed cells having a cell diameter of less than 100 nm is 30% or more in terms of number, and the density of the foam is 0.01-0.85 g/cm.

Description

  The present invention relates to an elastomer composition foam formed from an elastomer and a thermoplastic resin, and a method for producing the same.

  Materials used for automobiles and the like are required to be lighter from the viewpoint of environmental response in recent years. One of the means for reducing the weight is foaming. For example, an elastomer and a resin foam refer to a material having a small density in which a large number of small pores communicating with each other or small bubbles not communicating with each other are uniformly distributed. Examples of elastomer and resin foams in practical use include polystyrene foam, ABS (acrylonitrile butadiene styrene copolymer) foam, polyethylene foam, polypropylene foam, polyurethane foam, vinyl chloride resin foam, EPDM (ethylene And propylene / diene copolymer) foam.

Methods for producing elastomer and resin foams are roughly classified into batch type and continuous extrusion type.
The batch-type production method includes, for example, arranging an elastomer and resin composition in an autoclave, dissolving the foaming agent in the composition, and lowering the pressure in the autoclave to dissolve the foaming agent in the composition. Is a method for obtaining a foamed product of an elastomer and a resin by supersaturating. If a batch type method is used, since precise control of manufacturing conditions is relatively easy, there is an advantage that a foam having fine foam cells can be manufactured (see, for example, Patent Documents 1 to 5).

  On the other hand, in the continuous extrusion type production method, a composition of a molten elastomer and a molten resin containing a foaming agent was prepared in a reduced-pressure atmosphere, and the composition was continuously extruded from a die and dissolved in the composition. This is a method of obtaining a foamed product of an elastomer and a resin composition by supersaturating the foaming agent. According to the continuous extrusion manufacturing method, a foam having a large size can be obtained, and from the viewpoint of mass production, it is excellent in terms of cost (for example, see Patent Document 6).

As described above, the batch-type production method has an advantage that a foam having fine foam cells can be produced, but is not suitable for mass production and may be disadvantageous in terms of cost.
On the other hand, in the continuous extrusion manufacturing method, although there is a cost advantage, it is difficult to precisely control the manufacturing conditions. In particular, since it is difficult to control the cell growth of the foamed cells in the molten elastomer and the molten resin, it was difficult to obtain a foamed product having an average value of the major axis of the foamed cells of 4 μm or less.

  As a technique for reducing the foam cell, for example, Patent Document 7 describes a method of crosslinking an elastomer and a resin after cell formation (foaming completion) in order to control the growth of the formed foam cell. Making the cell small in this way is important in that it suppresses the deterioration of mechanical properties, which is the greatest drawback of the foam. However, in this method, the ratio of foamed cells having a cell diameter of 0.1 μm or more is large, and it cannot be said that a decrease in mechanical strength can be sufficiently suppressed.

JP-A-6-057026 Japanese Patent Laid-Open No. 6-254981 JP-A-7-138401 JP 2000-281829 A JP 2001-055464 A JP 2003-176375 A Japanese Patent No. 399386

  The subject of this invention is providing the foam which has a fine foam cell, and is excellent also in cost from the viewpoint of mass production, and its manufacturing method. In addition, by forming such fine foam cells, it is possible to suppress the reduction of the mechanical strength of the foam and to reduce the weight of the product.

  The inventors of the present invention can control the growth of foamed cells by melt-mixing a specific amount of an elastomer and a thermoplastic resin to form a mixture, and crosslinking and foaming the mixture, and thus an elastomer having fine foamed cells. It has been found that a composition foam can be obtained, and the present invention has been completed.

That is, the present invention and preferred embodiments thereof will be described respectively by the following [1] to [22].
[1] In the present invention, 10 to 90 parts by weight of the elastomer (A) and 10 to 90 parts by weight of the thermoplastic resin (B) (provided that the total of (A) and (B) is 100 parts by weight). It has a foam cell having an average cell diameter measured by a scanning electron microscope (SEM) of 50 to 3000 nm, which is obtained by melting and mixing to form a mixture, and crosslinking and foaming the mixture. The present invention relates to a foamed elastomer composition, wherein the ratio of foamed cells having a cell diameter of less than 100 nm is 30% or more on a number basis, and the density is 0.01 to 0.85 g / cm ³ .

  [2] In the present invention described in [1] and the like, the crosslinking agent (C) is 0.01 to 100 parts by weight with respect to a total of 100 parts by weight of the elastomer (A) and the thermoplastic resin (B). An elastomer composition foam obtained by use in a proportion of 50 parts by weight is preferred.

  [3] In the present invention described in [2] and the like, as the crosslinking agent (C), a SiH group-containing compound (C1) having at least two SiH groups in one molecule, an organic peroxide (C2) And phenolic resin (C3).

  [4] In the invention described in [1], [2], [3], or the like, a foaming agent (100% by weight) with respect to a total of 100 parts by weight of the elastomer (A) and the thermoplastic resin (B). An elastomer composition foam obtained by using D) in a proportion of 0.1 to 200 parts by weight is preferred.

  [5] In the elastomer composition foam described in [4] and the like, the foaming agent (D) is preferably selected from carbon dioxide (D1), nitrogen (D2), and a chemical foaming agent (D3). It is.

  [6] In the present invention according to any one of [1] to [5], an inorganic filler (E) with respect to a total of 100 parts by weight of the elastomer (A) and the thermoplastic resin (B). Is preferably an elastomer composition foam obtained by using 0.01 to 100 parts by weight.

  [7] In the present invention according to any one of [1] to [6], the softening agent (F) is added to 100 parts by weight of the elastomer (A) and the thermoplastic resin (B). The elastomer composition foam obtained by using 1 to 150 parts by weight is preferred.

  [8] In the present invention according to any one of [1] to [7], the elastomer (A) is an ethylene / α-olefin copolymer comprising ethylene and an α-olefin having 3 to 20 carbon atoms. Preferred is a composite rubber and an elastomer composition foam which is at least one selected from ethylene, an α-olefin / non-conjugated polyene copolymer rubber composed of ethylene, an α-olefin having 3 to 20 carbon atoms, and a non-conjugated polyene. It is.

[9] In the present invention described in [8] and the like, it is preferable that the elastomer (A) is an ethylene / propylene / non-conjugated polyene copolymer rubber.
[10] In the present invention according to any one of [1] to [9], the thermoplastic resin (B) is obtained by (co) polymerizing an α-olefin having 2 to 20 carbon atoms. A (co) polymer is preferred.

  [11] In the present invention described in [10] above, the thermoplastic resin (B) is composed of propylene homopolymer and propylene and an α-olefin having 2 to 20 carbon atoms (propylene). And at least one selected from copolymers of

  [12] In the present invention according to any one of [1] to [11], a sea phase formed from the thermoplastic resin (B) and an island phase formed from the elastomer (A). It is preferable that the foam is an elastomer composition having a sea-island structure.

  [13] In the present invention according to any one of [1] to [12], an elastomer composition foam in which cells are selectively formed in an island phase formed from the elastomer (A) is preferable. It is.

  [14] In the present invention described in [12] or [13] above, the mixture is foamed after the crosslinking of the elastomer (A) forming the island phase is started, or in the foaming stage of the mixture An elastomer composition foam obtained by crosslinking the elastomer (A) forming the island phase is suitable.

[15] In the present invention, the elastomer (A) is 10 to 90 parts by weight and the thermoplastic resin (B) is 10 to 90 parts by weight (provided that the total of (A) and (B) is 100 parts by weight). And 0.01 to 50 parts by weight of a cross-linking agent (C) are melt-mixed to form a mixture, and the step of cross-linking and foaming the mixture is carried out with a scanning electron microscope (SEM) The measured average cell diameter is 50 to 3000 nm, and the ratio of the foamed cells having a cell diameter of less than 100 nm is 30% or more on a number basis, and the density is 0.01 to 0.85 g. The present invention relates to a method for producing an elastomer composition foam that is / cm ³ .

  [16] In the production method of the present invention described in [15] above, the mixture is foamed after the crosslinking of the elastomer (A) is started, or the elastomer (A) is crosslinked in the foaming stage of the mixture. It is preferable to produce an elastomer composition foam.

  [17] In the present invention described in [15] or [16] above, as the crosslinking agent (C), an SiH group-containing compound (C1) having at least two SiH groups in one molecule, an organic peroxide It is preferable to produce an elastomer composition foam using a crosslinking agent (C) selected from (C2) and a phenol-based resin (C3).

  [18] In the present invention according to any one of [15], [16] or [17], a foaming agent is used with respect to a total of 100 parts by weight of the elastomer (A) and the thermoplastic resin (B). It is preferable to produce an elastomer composition foam using (D) in a proportion of 0.1 to 200 parts by weight.

  [19] In the present invention described in [18] and the like, a foaming agent (D) selected from carbon dioxide (D1), nitrogen (D2), and chemical foaming agent (D3) is used as the foaming agent (D). It is preferred to use to produce an elastomer composition foam.

  [20] In the present invention according to any one of [15] to [19], an inorganic filler (E) with respect to a total of 100 parts by weight of the elastomer (A) and the thermoplastic resin (B). Is preferably used in a proportion of 0.01 to 100 parts by weight to produce an elastomer composition foam.

  [21] In the present invention according to any one of [15] to [20], the softening agent (F) is added to 100 parts by weight of the total of the elastomer (A) and the thermoplastic resin (B). It is preferable to use an amount of 1-150 parts by weight to produce an elastomer composition foam.

  [22] In the present invention according to any one of [15] to [21], the elastomer (A) is an ethylene / α-olefin copolymer comprising ethylene and an α-olefin having 3 to 20 carbon atoms. Elastomer composition foam using at least one selected from a combined rubber, and an ethylene / α-olefin / nonconjugated polyene copolymer rubber comprising ethylene, an α-olefin having 3 to 20 carbon atoms, and a nonconjugated polyene Is preferably produced.

  [23] In the present invention according to any one of [15] to [22], the thermoplastic resin (B) is obtained by (co) polymerizing an α-olefin having 2 to 20 carbon atoms. It is preferred to produce an elastomer composition foam that is a (co) polymer.

  [24] In the present invention according to any one of [15] to [23], including a sea phase formed from the thermoplastic resin (B) and an island phase formed from the elastomer (A). It is preferable to produce an elastomer composition foam having a sea-island structure.

  [25] In the present invention according to any one of [15] to [24], an elastomer composition foam in which cells are selectively formed in an island phase formed from the elastomer (A) is produced. Is preferred.

  According to the present invention, it is possible to produce an elastomer composition foam having fine foam cells by controlling the growth of the foam cells. In addition, by forming such fine foam cells, it is possible to suppress a decrease in the mechanical strength of the foam and to reduce the weight of the product.

FIG. 1 is a schematic view showing an apparatus for producing an elastomer composition foam.

The details of the elastomer composition foam of the present invention and the production method thereof will be described below.
<Elastomer composition foam>
The elastomer composition foam of the present invention comprises 10 to 90 parts by weight of the elastomer (A) and 10 to 90 parts by weight of the thermoplastic resin (B) (provided that the total of (A) and (B) is 100 parts by weight. .) Is melt mixed to form a mixture, which is obtained by crosslinking and foaming.

The foam of the present invention has foam cells having an average cell diameter of 50 to 3000 nm as measured by a scanning electron microscope (SEM), and the ratio of foam cells having a cell diameter of less than 100 nm among the foam cells is based on several criteria. It is 30% or more, and the density is 0.01 to 0.85 g / cm ³ .

The average cell diameter of the foamed cells is preferably 50 to 2000 nm, more preferably 50 to 1000 nm. The proportion of foamed cells having a cell diameter of less than 100 nm among the foamed cells is preferably 40% or more on a number basis. The density of the foam of the present invention is preferably 0.1 to 0.85 g / cm ³ , more preferably 0.2 to 0.85 g / cm ³ , still more preferably 0.3 to 0.85 g / cm ³ . is there. Thus, the foam of the present invention has excellent properties such as heat insulation, light weight, reflection characteristics, and mechanical strength because the foamed cells are miniaturized and the density is small.

  In the present invention, it is preferable to use a crosslinking agent (C) from the viewpoint of efficiently proceeding with crosslinking together with the elastomer (A) and the thermoplastic resin (B), and foaming from the viewpoint of efficiently promoting foaming. It is preferable to use an agent (D). Moreover, you may use an inorganic filler (E), a softening agent (F), etc. as needed.

  The elastomer composition foam of the present invention usually has a sea-island structure including a sea phase formed from the thermoplastic resin (B) and an island phase formed from the elastomer (A). Here, the elastomer (A) constituting the island phase usually has a crosslinked structure. In other words, the elastomer (A) tends to crosslink and decrease in fluidity or not flow at the time of crosslinking following melt mixing. Moreover, the said foam cell is selectively formed in the island phase which consists of an elastomer (A) by following the manufacturing method of the elastomer composition foam mentioned later.

It is selectively formed in the island phase consisting of the elastomer (A). The cell density of the cells formed in the island phase elastomer (A) is ρ _A and the sea phase is formed in the thermoplastic resin (B). When the cell density of the obtained cells is ρ _B , ρ _A / (ρ _A + ρ _B ) × 100 is 70 or more, preferably 80 or more, more preferably 90 or more.

The cell density was calculated by calculating the number of cells per 1 cm ² from the number of cells in 100 μm ^{2 obtained} by image processing of a photograph taken with a scanning electron microscope, and setting the cell density to the cell density.
Hereafter, each said component is demonstrated.

[Elastomer (A)]
Examples of the elastomer (A) include acrylonitrile butadiene rubber (NBR), butadiene rubber (BR), natural rubber (NR), high styrene rubber (HSR), butyl rubber (IIR), isoprene rubber (IR), chloroprene rubber ( CR), styrene-butadiene rubber (SBR), silicone rubber, ethylene / α-olefin copolymer rubber comprising ethylene and an α-olefin having 3 to 20 carbon atoms, propylene and α- having 3 to 20 carbon atoms Propylene / α-olefin copolymer rubber composed of olefin (excluding propylene), ethylene / α-olefin / nonconjugated polyene copolymer composed of ethylene, α-olefin having 3 to 20 carbon atoms and nonconjugated polyene Rubber, propylene and α-olefin having 3 to 20 carbon atoms (excluding propylene) Such a propylene-alpha-olefin-non-conjugated polyene copolymer rubber consisting of a non-conjugated polyene and the like. An elastomer (A) may be used individually by 1 type, and may be used in combination of 2 or more type.

The density of the elastomer (A), from the viewpoint of weight reduction, it is preferably 1.20 g / cm ³ or less, more preferably less than 0.90g / cm ^3, 0.80~0.89g / cm ³ is more preferable. Among the above examples, ethylene / α-olefin / non-conjugated polyene copolymer rubber and ethylene / α-olefin / non-conjugated polyene copolymer rubber having lower density are preferably used. A combined rubber is more preferably used, and an ethylene / propylene / non-conjugated polyene copolymer rubber is particularly preferably used. A density is an average value about each density when measuring three arbitrary places of an elastomer (A) using an electron density meter (Mirage Co., Ltd., MD-200S).

  The intrinsic viscosity [η] of the elastomer (A) is preferably 0.6 to 6.0 dl / g, more preferably 0.8 to 5.0 dl / g. When [η] is below the above range, the molecular weight of the elastomer (A) is extremely low, and therefore the mechanical properties of the resulting elastomer composition foam may be deteriorated. When [η] exceeds the above range, the viscosity of the elastomer (A) during dispersion kneading or dynamic heat treatment becomes extremely high, and handling may be difficult. When the elastomer (A) is an ethylene / α-olefin / non-conjugated polyene copolymer rubber, the intrinsic viscosity measured in 135 ° C. decalin (decahydronaphthalene) is applied.

  Examples of the α-olefin having 3 to 20 carbon atoms include propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene, 1-octene, 1-nonene, 1-nonene, Examples include decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene and the like. The said C3-C20 alpha olefin may be used individually by 1 type, and may be used in combination of 2 or more type.

Examples of the non-conjugated polyene include 1,4-hexadiene, 3-methyl-1,4-hexadiene, 4-methyl-1,4-hexadiene, 5-methyl-1,4-hexadiene, and 4,5-dimethyl. Chain unconjugated dienes such as -1,4-hexadiene and 7-methyl-1,6-octadiene;
Methyltetrahydroindene, 5-ethylidene-2-norbornene, 5-methylene-2-norbornene, 5-isopropylidene-2-norbornene, 5-vinylidene-2-norbornene, 6-chloromethyl-5-isopropenyl-2-norbornene Cyclic nonconjugated dienes such as 5-vinyl-2-norbornene, 5-isopropenyl-2-norbornene, 5-isobutenyl-2-norbornene, cyclopentadiene, norbornadiene;
2,3-diisopropylidene-5-norbornene, 2-ethylidene-3-isopropylidene-5-norbornene, 2-propenyl-2,2-norbornadiene, 4-ethylidene-8-methyl-1,7-nonadiene, 4 -Triene such as ethylidene-1,7-undecadiene;

  Among these, 5-ethylidene-2-norbornene, 5-vinyl-2-norbornene, cyclopentadiene, and 4-ethylidene-8-methyl-1,7-nonadiene are preferable. The said nonconjugated polyene may be used individually by 1 type, and may be used in combination of 2 or more type.

In the ethylene / α-olefin copolymer rubber and the ethylene / α-olefin / non-conjugated polyene copolymer rubber, the constituent unit content (ethylene content) derived from ethylene is usually 50 mol% or more, preferably 50 to 50%. 90 mol%, more preferably 60 to 85 mol%, and the content of structural units derived from an α-olefin having 3 to 20 carbon atoms (α-olefin content) is usually 50 mol% or less, preferably 50 to It is 10 mol%, More preferably, it is 40-15 mol%. However, the total of the ethylene content and the α-olefin content is 100 mol%. The rubber composition is determined by measurement by ¹³ C-NMR. In the ethylene / α-olefin / non-conjugated polyene copolymer rubber, the constituent unit content derived from the non-conjugated polyene (non-conjugated polyene content) is usually 0.1 to 30, preferably 0.00. 1-25.

As the elastomer (A), an elastomer produced by a conventionally known polymerization method can be used. Specific examples include ethylene / propylene / 5-ethylidene-2-norbornene copolymer rubber (ethylene content = 80 mol%, propylene content = 20 mol%, iodine value = 12, [η] = 3.5 dl / g, Density 0.87 g / cm ³ ), ethylene / propylene / 5-ethylidene-2-norbornene copolymer rubber (ethylene content = 80 mol%, propylene content 20 mol%, iodine value = 12, [η] = 4.5 dl) / G, density 0.87 g / cm ³ ) and the like.

  In the present invention, the elastomer (A) is 10 to 90 parts by weight, preferably 15 to 85 parts by weight, particularly preferably 20 to 80 parts by weight based on a total of 100 parts by weight of the elastomer (A) and the thermoplastic resin (B). Used in parts by weight. When the usage-amount of an elastomer (A) exists in the said range, it is preferable from a viewpoint that a sea island structure is stabilized. When the usage-amount of an elastomer (A) exceeds the said range, formation of a fine foam cell will become difficult and mechanical characteristics will fall. When the usage-amount of an elastomer (A) is less than the said range, weight reduction of a foam will become difficult.

[Thermoplastic resin (B)]
As the thermoplastic resin (B), a conventionally known thermoplastic resin, the density is usually 0.90 g / cm ³ or more, preferably include the 0.90~1.0g / cm ^3. A density is an average value about each density when measuring three arbitrary places of a thermoplastic resin (B) using an electron density meter (Mirage Co., Ltd., MD-200S).

  The intrinsic viscosity [η] of the thermoplastic resin (B) is preferably 0.5 to 6.0 dl / g, and more preferably 0.6 to 5.0 dl / g. When [η] is less than the above range, the molecular weight of the thermoplastic resin (B) is extremely low, which may deteriorate the mechanical properties of the resulting elastomer composition foam. When [η] exceeds the above range, the viscosity at the time of melting becomes extremely high and handling may be difficult. In addition, when a thermoplastic resin (B) is polyolefin resin, the intrinsic viscosity measured in 135 degreeC decalin (decahydronaphthalene) is applied.

  Examples of the thermoplastic resin (B) include low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear low-density polyethylene, ethylene / propylene copolymer and other ethylene polymers, propylene homopolymer, propylene block copolymer (Co) polymers obtained by (co) polymerizing α-olefins having 2 to 20 carbon atoms such as propylene polymers such as polymers and propylene random copolymers; cyclic olefin (co) polymers; polystyrene Styrene polymers such as acrylonitrile / styrene copolymer and acrylonitrile / butadiene / styrene copolymer; polyvinyl chloride and polyvinylidene chloride; ethylene / methacrylic acid copolymer, ethylene / methacrylic acid ester copolymer, ethylene / Vinyl acetate copolymer and Polyethylene and polymethacrylate; Polyesters such as polyethylene terephthalate and polybutylene terephthalate; Nylon 6, nylon 11, nylon 12, nylon 46, nylon 66, nylon MXD6, wholly aromatic polyamide and semi-aromatic polyamide And polyamides such as polyacetal. A thermoplastic resin (B) may be used individually by 1 type, and may be used in combination of 2 or more type. “(Co) polymerization” means polymerization or copolymerization, and “(co) polymer” means a polymer obtained by polymerization or copolymerization.

  Among these, (co) polymers obtained by (co) polymerizing α-olefins having 2 to 20 carbon atoms are preferred, and propylene homopolymer and propylene mainly composed of propylene and 2 carbon atoms. More preferred are copolymers with ~ 20 α-olefins (excluding propylene). Examples of the copolymer mainly composed of propylene include a propylene block copolymer, a propylene random copolymer, and a propylene / ethylene copolymer. “Propylene-based” means that the propylene content is 55 mol% or more.

  Examples of the α-olefin having 2 to 20 carbon atoms include ethylene, propylene, butene-1, pentene-1, 2-methylbutene-1, 3-methylbutene-1, hexene-1, 3-methylpentene-1, 4 Methylpentene-1,3,3-dimethylpentene-1, heptene-1, methylhexene-1, dimethylpentene-1, trimethylbutene-1, ethylpentene-1, octene-1, methylpentene-1, dimethylhexene -1, trimethylpentene-1, ethylhexene-1, methylethylpentene-1, diethylbutene-1, propylpentene-1, decene-1, methylnonene-1, dimethyloctene-1, trimethylheptene-1, ethyloctene -1, methylethylheptene-1, diethylhexene-1, dodecene-1 and hexa Such as decene-1, and the like.

As the thermoplastic resin (B), a thermoplastic resin produced by a conventionally known method can be used. Specific examples include propylene homopolymer ([η] = 2.4 dl / g, density 0.91 g / cm ³ ), propylene random copolymer ([η] = 2.4 dl / g, density 0.91 g / cm). ³ ), propylene block copolymer ([η] = 3.5 dl / g, density 0.91 g / cm ³ ) and the like.

  In the present invention, the thermoplastic resin (B) is 10 to 90 parts by weight, preferably 15 to 85 parts by weight, particularly preferably 20 parts per 100 parts by weight in total of the elastomer (A) and the thermoplastic resin (B). Used at a ratio of ˜80 parts by weight. When the usage-amount of a thermoplastic resin (B) exists in the said range, it is preferable from a viewpoint that a sea island structure is stabilized.

[Crosslinking agent (C)]
In this invention, it is preferable to use a crosslinking agent (C) with an elastomer (A) and a thermoplastic resin (B) from a viewpoint of advancing bridge | crosslinking efficiently. In the present invention, it is presumed that the crosslinking agent (C) and the elastomer (A) mainly react to form a crosslinked structure of the elastomer (A). Due to the presence of this cross-linked structure, the growth of the foam cells can be effectively controlled, and the foam cells can be selectively formed in the island phase made of the elastomer (A).

  The crosslinking agent (C) is usually 0.01 to 50 parts by weight, preferably 0.01 to 30 parts by weight, more preferably 100 parts by weight in total of the elastomer (A) and the thermoplastic resin (B). It can be used at a ratio of 0.05 to 10 parts by weight.

  The cross-linking agent (C) can be added from a hopper as a raw material supply port or from the middle of the extruder. When the cross-linking agent (C) is added from the middle of the extruder, the addition position may be after the melting position of the raw material, and may be any of the upper part, the lower part and the horizontal part of the cylinder, and the foaming agent (D) It may be before or after the addition position. The crosslinking agent (C) may be mixed with oil or the like and added via a pump in a liquid state, or may be melt-kneaded and side-fed using an extruder or the like.

  As the crosslinking agent (C), a SiH group-containing compound (C1) having at least two SiH groups in one molecule, an organic peroxide (C2), a phenol resin (C3) and the like are preferable. As the crosslinking agent (C), one kind selected from these crosslinking agents may be used alone, or two or more kinds may be used in combination.

<< SiH group-containing compound (C1) >>
The SiH group-containing compound (C1) has at least 2, preferably 3 or more, more preferably 3-10, particularly preferably 6-10, hydrogen atoms directly bonded to silicon atoms, that is, SiH groups in one molecule. It is a compound having a number. There is no restriction | limiting in particular in the molecular structure of a SiH group containing compound (C1), For example, the resinous material etc. which were manufactured conventionally, for example, a linear, cyclic | annular or branched structure, or a three-dimensional network structure, can be used.

As the SiH group-containing compound (C1), for example, a compound represented by a general composition formula R _b H _c SiO _{(4-bc) / 2} can be used. R is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 10 carbon atoms, particularly 1 to 8 carbon atoms, excluding those having an aliphatic unsaturated bond. Examples of the monovalent hydrocarbon group include alkyl groups other than those having an aliphatic unsaturated bond; halogen-substituted alkyl groups such as a phenyl group and a trifluoropropyl group. Among these, a methyl group, an ethyl group, a propyl group, a phenyl group, and a trifluoropropyl group are preferable, and a methyl group and a phenyl group are particularly preferable. b is 0 ≦ b <3, preferably 0.6 <b <2.2, particularly preferably 1.5 ≦ b ≦ 2, and c is 0 <c ≦ 3, preferably 0.002 ≦ c. <2, particularly preferably 0.01 ≦ c ≦ 1, and b + c is 0 <b + c ≦ 3, preferably 1.5 <b + c ≦ 2.7.

  The SiH group-containing compound (C1) preferably has 2 to 100 silicon atoms, more preferably 2 to 50, particularly preferably 2 to 20, most preferably 2 to 10 silicon atoms in one molecule. Genpolysiloxane.

Specific examples of the SiH group-containing compound (C1) include 1,1,3,3-tetramethyldisiloxane, 1,3,5,7-tetramethyltetracyclosiloxane, 1,3,5,7, Siloxane oligomers such as 8-pentamethylpentacyclosiloxane; molecular chain both ends trimethylsiloxy group-blocked methylhydrogenpolysiloxane, molecular chain both ends trimethylsiloxy group-blocked dimethylsiloxane / methylhydrogensiloxane copolymer, molecular chain both ends silanol Blocked methylhydrogenpolysiloxane, molecular chain both ends silanol group blocked dimethylsiloxane / methylhydrogensiloxane copolymer, molecular chain both ends dimethylhydrogensiloxy group blocked dimethylpolysiloxane, molecular chain both ends dimethylhydrogensiloxy group blocked Methyl hydrogen Polysiloxane, dimethylhydrogensiloxy group-blocked dimethylsiloxane / methylhydrogensiloxane copolymer, both ends of molecular chain, R ₂ (H) SiO _1/2 unit and SiO _4/2 unit, optionally R ₃ SiO Examples thereof include a silicone resin that may contain _1/2 units, R ₂ SiO _2/2 units, R (H) SiO _2/2 units, (H) SiO _3/2 units, or RSiO _3/2 units. The same as R in the general composition formula).

As the methyl hydrogen polysiloxane blocked with trimethylsiloxy groups at both ends of the molecular chain, (CH ₃ ) ₃ SiO — (— SiH (CH ₃ ) —O—) _d —Si (CH ₃ ) ₃ (wherein d is 2 or more) And a compound in which part or all of the methyl group is substituted with an ethyl group, a propyl group, a phenyl group, a trifluoropropyl group, or the like.

The trimethylsiloxy group-blocked dimethylsiloxane / methylhydrogensiloxane copolymer at both molecular chain ends is (CH ₃ ) ₃ SiO — (— Si (CH ₃ ) ₂ —O—) _e — (— SiH (CH ₃ ) — O-) _f -Si (CH ₃ ) ₃ (wherein e is an integer of 1 or more and f is an integer of 2 or more), a part or all of the methyl groups in the compound And compounds substituted with an ethyl group, a propyl group, a phenyl group, a trifluoropropyl group, and the like.

As the molecular hydrogen-terminated silanol-blocked methyl hydrogen polysiloxane, a compound represented by HOSi (CH ₃ ) ₂ O — (— SiH (CH ₃ ) —O—) ₂ —Si (CH ₃ ) ₂ OH, the compound In which a part or all of the methyl group is substituted with an ethyl group, a propyl group, a phenyl group, a trifluoropropyl group, or the like.

Examples of the dimethylsiloxane / methylhydrogensiloxane copolymer blocked with silanol groups at both ends of the molecular chain include HOSi (CH ₃ ) ₂ O — (— Si (CH ₃ ) ₂ —O—) _e — (— SiH (CH ₃ ) — O-) _f- Si (CH ₃ ) ₂ OH (wherein e is an integer of 1 or more and f is an integer of 2 or more), a part or all of methyl groups in the compound And the like in which is substituted with an ethyl group, a propyl group, a phenyl group, a trifluoropropyl group, or the like.

As the dimethylpolysiloxane blocked with dimethylhydrogensiloxy group at both ends of the molecular chain, HSi (CH ₃ ) ₂ O — (— Si (CH ₃ ) ₂ —O—) _e —Si (CH ₃ ) ₂ H (e in the formula) Is an integer of 1 or more), and a compound in which part or all of the methyl group is substituted with an ethyl group, a propyl group, a phenyl group, a trifluoropropyl group, or the like.

The molecular chain both ends dimethylhydrogensiloxy group-capped methylhydrogenpolysiloxane includes HSi (CH ₃ ) ₂ O — (— SiH (CH ₃ ) —O—) _e —Si (CH ₃ ) ₂ H (in the formula e is an integer of 1 or more), and compounds in which part or all of the methyl group in the compound is substituted with an ethyl group, a propyl group, a phenyl group, a trifluoropropyl group, or the like.

As the dimethylsiloxane / methylhydrogensiloxane copolymer blocked with dimethylhydrogensiloxy group at both ends of the molecular chain, HSi (CH ₃ ) ₂ O — (— Si (CH ₃ ) ₂ —O—) _e — (— SiH (CH ₃ ) —O—) _h— Si (CH ₃ ) ₂ H (wherein e and h are each an integer of 1 or more), a part or all of the methyl group in the compound is ethylated And a compound substituted with a group, a propyl group, a phenyl group, a trifluoropropyl group, and the like.

  Such a compound can be produced by a conventionally known method, for example, octamethylcyclotetrasiloxane and / or tetramethylcyclotetrasiloxane, and hexamethyldisiloxane or 1,3-dihydro-1, which can be a terminal group. A compound containing a triorganosilyl group or a diorganohydrogensiloxy group, such as 1,3,3-tetramethyldisiloxane, in the presence of a catalyst such as sulfuric acid, trifluoromethanesulfonic acid, methanesulfonic acid, and the like. It can be easily obtained by equilibrating at a temperature of about 0 ° C to + 40 ° C.

<< Organic peroxide (C2) >>
As the organic peroxide (C2), dicumyl peroxide, di-t-butyl peroxide, di-t-butylperoxy-3,3,5-trimethylcyclohexane, t-butylcumyl peroxide, di-t -Amyl peroxide, t-butyl hydroperoxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne-3,2,5-dimethyl-2,5-di (benzoylperoxy) Dialkyl peroxides such as hexane, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, α, α'-bis (t-butylperoxy-m-isopropyl) benzene; t-butyl Peroxyacetate, t-butylperoxyisobutyrate, t-butylperoxypivalate, t-butylperoxymaleic acid, t-butylperoxy Odekanoeto, t- butyl peroxybenzoate, peroxy esters di -t- butyl peroxy phthalate; and ketone peroxides such as dicyclohexanone peroxide. An organic peroxide (C2) may be used individually by 1 type, and may be used in combination of 2 or more type.

  Among these, organic peroxides having a one-minute half-life temperature in the range of 130 to 200 ° C. are preferred, specifically 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, Dicumyl peroxide, di-t-butyl peroxide, di-t-butylperoxy-3,3,5-trimethylcyclohexane, t-butylcumyl peroxide, di-t-amyl peroxide, t-butyl hydroperoxide Examples include oxides.

  In the present invention, sulfur, dioximes, N-methyl-N-4-dinitrosoaniline, nitrosobenzene, diphenylguanidine, in combination with the organic peroxide (C2), as long as the object of the present invention is not impaired. Peroxy crosslinking aids such as trimethylolpropane-N, N′-m-phenylenedimaleimide; divinylbenzene, triallyl cyanurate, triallyl isocyanurate; ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, A multifunctional methacrylate monomer such as trimethylolpropane trimethacrylate or allyl methacrylate; a multifunctional vinyl monomer such as vinyl butyrate or vinyl stearate can be blended.

<< Phenolic resin (C3) >>
Examples of the phenol resin (C3) include p-substituted phenol compounds represented by the following general formula (1), o-substituted phenol / aldehyde condensates, m-substituted phenol / aldehyde condensates, brominated alkylphenols, Examples include aldehyde condensates. Among these, p-substituted phenol compounds represented by the following general formula (1) are preferable. A phenol resin (C3) may be used individually by 1 type, and may be used in combination of 2 or more type.

式（１）中、Ｒは炭素原子数１〜１５の飽和炭化水素基であり、ｎは０〜１０の整数である。飽和炭化水素基としては、例えば、アルキル基が挙げられる。なお、一般式（１）で表されるｐ−置換フェノール系化合物は、アルカリ触媒の存在下における、ｐ−置換フェノールとアルデヒド（好ましくはホルムアルデヒド）との縮合反応により得ることができる。

In formula (1), R is a saturated hydrocarbon group having 1 to 15 carbon atoms, and n is an integer of 0 to 10. Examples of the saturated hydrocarbon group include an alkyl group. The p-substituted phenol compound represented by the general formula (1) can be obtained by a condensation reaction between a p-substituted phenol and an aldehyde (preferably formaldehyde) in the presence of an alkali catalyst.

  In the present invention, a phenolic resin (C3), halides such as stannous chloride, ferric chloride, and cupric chloride, zinc oxide, and the like may be blended within a range that does not impair the purpose of the present invention. it can.

[Foaming agent (D)]
In this invention, it is preferable to use a foaming agent (D) with an elastomer (A) and a thermoplastic resin (B) from a viewpoint of advancing foaming effectively. Examples of the foaming agent (D) include carbon dioxide (D1), nitrogen (D2), and chemical foaming agent (D3).

  Carbon dioxide (D1) and nitrogen (D2), which are physical foaming agents, do not need to be vaporized, are inexpensive, and have extremely low risk of environmental pollution and fire. Carbon dioxide (D1) and nitrogen (D2) can be used in a cylinder if they are equipment that produces foamed products on a small scale, and can be supplied to the extruder through a pressure reducing valve to produce foamed products on a large scale. If it is equipment to be installed, storage tanks such as liquefied carbon dioxide and liquefied nitrogen can be installed, passed through a heat exchanger, vaporized, passed through piping, and supplied to the extruder through a pressure reducing valve.

  The chemical foaming agent (D3) is a thermal decomposition type foaming agent, for example, an inorganic foaming agent such as sodium bicarbonate, sodium carbonate, ammonium bicarbonate, ammonium carbonate, ammonium nitrite; N, N′-dimethyl-N, Nitroso compounds such as N′-dinitrosoterephthalamide and N, N′-dinitrosopentamethylenetetramine (DPT); azodicarbonamide (ADCA), azobisisobutyronitrile (AZBN), azobiscyclohexylnitrile, azodiamino Azo compounds such as benzene and barium azodicarboxylate; benzenesulfonyl hydrazide (BSH), toluenesulfonyl hydrazide (TSH), p, p′-oxybis (benzenesulfonyl hydrazide) (OBSH), diphenylsulfone-3,3 ′ -Sulfonyl such as disulfonylhydrazide Hydrazide compounds; azide compounds such as calcium azide, 4,4′-diphenyldisulfonyl azide, p-toluenesulfonyl azide, and the like.

  When the foaming agent (D) is used in the present invention, the (D) is usually 0.1 to 200 parts by weight, preferably 100 parts by weight in total of the elastomer (A) and the thermoplastic resin (B). Is used in a proportion of 0.2 to 30 parts by weight, more preferably 0.5 to 10 parts by weight.

  In the case of carbon dioxide (D1) or nitrogen (D2), the blowing agent (D) can be added from the middle of the extruder, and in the case of the chemical foaming agent (D3), it can be added from the hopper or the middle of the extruder as the raw material supply port. . When the foaming agent (D) is added from the middle of the extruder, the addition position may be after the melting position of the raw material, and may be any of the upper part, the lower part and the horizontal part of the cylinder, and the crosslinking agent (C). It may be before or after the addition position.

  In the case of carbon dioxide (D1), it is added in a liquefied state, in a gaseous state or in a supercritical state, in the case of nitrogen (D2), it is added in a gaseous state or in a supercritical state, and in the case of a chemical foaming agent (D3), an extruder or the like And may be side-fed by melt-kneading.

  Supercritical fluids have excellent solubility close to liquid and excellent diffusivity close to gas, so they are highly soluble in resins and elastomers and have a high diffusion rate in resins, etc. Thus, the foaming agent can be impregnated in the resin or the like. Therefore, the blowing agent added to the extruder is in a supercritical state in the case of carbon dioxide (D1) or nitrogen (D2), and in the case of the chemical blowing agent (D3), the carbon dioxide or nitrogen generated after the decomposition is supercritical. It is preferable to use it under conditions that result in a critical state.

  Moreover, a foaming auxiliary agent can also be used as needed. The foaming assistant functions to lower the decomposition temperature of the foaming agent, accelerate the decomposition, and make the bubbles uniform. Examples of the foaming aid include compounds containing metals such as zinc, calcium, lead, iron, and barium; organic acids such as citric acid, salicylic acid, phthalic acid, and oxalic acid; urea or derivatives thereof.

  When a foaming aid is used in the present invention, the foaming aid is usually 0.1 to 20 parts by weight, preferably 1 to 20 parts by weight with respect to a total of 100 parts by weight of the elastomer (A) and the thermoplastic resin (B). It is used at a ratio of 10 parts by weight.

[Inorganic filler (E)]
In this invention, it is preferable to use an inorganic filler (E) with an elastomer (A) and a thermoplastic resin (B) from a viewpoint of the cell number increase of a fine foam cell.

  As the inorganic filler (E), calcium carbonate, calcium oxide, calcium hydroxide, aluminum carbonate, aluminum oxide, aluminum hydroxide, barium carbonate, barium oxide, barium hydroxide, calcium silicate, clay, kaolin, talc, silica , Silica compound, diatomaceous earth, mica powder, asbestos, alumina, barium sulfate, aluminum sulfate, calcium sulfate, basic magnesium carbonate, molybdenum disulfide, graphite, glass fiber, glass bulb, shirasu balloon, basic magnesium sulfate whisker, titanium Examples thereof include calcium acid whisker and aluminum borate whisker.

  When the inorganic filler (E) is used in the present invention, the (E) is usually 0.01 to 100 parts by weight, preferably 100 parts by weight with respect to the total of 100 parts by weight of the elastomer (A) and the thermoplastic resin (B). Is used in a proportion of 0.1 to 20 parts by weight. When the usage-amount of an inorganic filler (E) exceeds the said range, it exists in the tendency for the rubber elasticity of an elastomer composition foam obtained, and a moldability to fall.

[Softener (F)]
In the present invention, from the viewpoint of making the elastomer composition flexible, a softener (F) other than the components (A) and (B) can be used together with the elastomer (A) and the thermoplastic resin (B).

  As softener (F), petroleum-based substances such as process oil, lubricating oil, paraffin, liquid paraffin, petroleum asphalt and petroleum jelly; synthetic oil such as low molecular weight ethylene / α-olefin random copolymer; coal tar, coal tar pitch Coal tars such as castor oil, linseed oil, rapeseed oil, soybean oil, coconut oil, etc .; waxes such as tall oil, beeswax, carnauba wax, lanolin; ricinoleic acid, palmitic acid, stearic acid, stearic acid Fatty acids such as barium and calcium stearate, or metal salts thereof; synthetic polymer materials such as petroleum resins, coumarone indene resins, and atactic polypropylene; ester plasticizers such as dioctyl phthalate, dioctyl adipate, and dioctyl sebacate; and other microcrystalline waxes , Sub (facts , Liquid polybutadiene, modified liquid polybutadiene, etc. liquid Thiokol and the like.

  Among these softeners, paraffinic or naphthenic process oils, or low molecular weight ethylene / α-olefin random copolymers are more preferable, and high viscosity paraffin with a low content of low molecular weight components that easily volatilize. A process oil or naphthenic process oil is particularly preferred. Here, the high viscosity type means one having a kinematic viscosity at 40 ° C. in the range of 100 to 10,000 centistokes.

  When the softener (F) is used in the present invention, the (F) is usually 1 to 150 parts by weight, preferably 1 to 150 parts by weight with respect to 100 parts by weight in total of the elastomer (A) and the thermoplastic resin (B). It is used at a ratio of 50 parts by weight.

[Other ingredients]
In the present invention, in addition to the elastomer (A) and the thermoplastic resin (B), additives such as a heat stabilizer, a weather resistance stabilizer, a lubricant, and a colorant may be used as necessary.

<Method for producing foam of elastomer composition>
The method for producing a foam of the elastomer composition of the present invention comprises 10 to 90 parts by weight of an elastomer (A) and 10 to 90 parts by weight of a thermoplastic resin (B) (however, the total of (A) and (B) is 100 weights). And 0.01 to 50 parts by weight of a crosslinking agent (C) are melt-mixed to form a mixture, and the mixture is crosslinked and foamed. The method of the present invention may be either a batch type or a continuous extrusion type, but is preferably a continuous extrusion type from the viewpoint of production cost.

  The elastomer composition foam produced by the above method has the above-mentioned foamed cell characteristics and density characteristics. In addition to the above, components that can be blended and preferred blending ratios of the respective components are as described in the section <Elastomer composition foam>.

  Foams formed from conventional elastomers are manufactured using batch and continuous extrusion methods. The continuous extrusion method can be mass-produced and is advantageous in terms of manufacturing cost. However, with conventional elastomers, it is difficult to obtain a foam having a large proportion (30% or more) of fine foam cells, particularly foam cells having a cell diameter of less than 100 nm.

  On the other hand, in the present invention, by using the elastomer (A) and the thermoplastic resin (B) and, if necessary, a cross-linking agent (C), a foaming agent (D), etc., even in a continuous extrusion type, a fine An elastomer composition foam having foam cells can be produced. Although the details of the reason are not clear, the present inventors presume as follows. In the manufacturing process of the foam, the foam cells generated in the sea phase formed from the thermoplastic resin (B) disappear, and therefore the foam cells exist mainly in the island phase formed from the crosslinked elastomer (A). ing. Since the foam cell is surrounded by the crosslinked elastomer (A), the growth is controlled and maintained in a refined state.

In the foam thus produced, the cells in the thermoplastic resin (B) which is the sea phase disappear, but the cells existing in the island phase formed from the crosslinked elastomer (A) are miniaturized. Therefore, the reduction in mechanical strength is suppressed, and the weight of the product is reduced. In order to maintain such functionality, the cell density of the cells formed in the elastomer (A) that is the island phase is ρ _A , and the cells formed in the thermoplastic resin (B) that is the sea phase. When the cell density is ρ _B , ρ _A / (ρ _A + ρ _B ) × 100 needs to be 70 or more, preferably 80 or more, more preferably 90 or more.

Hereinafter, a suitable aspect is demonstrated about the manufacturing method of the elastomer composition foam of this invention.
It is preferable that the said process includes the following sub processes.
(1) A step of supplying the elastomer (A) and the thermoplastic resin (B) to the extruder.
(2) The process of supplying a crosslinking agent (C) to an extruder through a crosslinking agent supply part.
(3) The process of supplying a foaming agent (D) to an extruder through a foaming agent supply part.

  In the sub-step (1), the elastomer (A) and the thermoplastic resin (B) are melted and mixed by rotation of the screw in the heated cylinder portion in the extruder to form a molten elastomer mixture. Along with the elastomer (A) and the thermoplastic resin (B), other components described above (eg, inorganic filler (E)) may be supplied. These raw materials are usually supplied to an extruder from a hopper.

  In the substep (2), the crosslinking agent (C) is supplied to the extruder. Here, the crosslinking agent (C) may be supplied to the extruder from a hopper that is a raw material supply port (that is, the crosslinking agent supply unit may be a hopper), or may be supplied from the middle of the extruder. . When the crosslinking agent (C), the elastomer (A), and the thermoplastic resin (B) are melt-kneaded and the cylinder temperature is an appropriate temperature, crosslinking of the elastomer (A) is started.

  In the substep (3), the foaming agent (D) is supplied to the extruder. Here, the foaming agent (D) may be supplied to the extruder from a hopper that is a raw material supply port according to the type (that is, the foaming agent supply unit may be a hopper), or in the middle of the extruder. You may supply from. When the foaming agent (D) is dissolved in a molten elastomer mixture composed of the elastomer (A) and the thermoplastic resin (B) and this mixture reaches the reduced pressure part of the extruder, foaming of the mixture is started.

  The above substeps (1) to (3) are not necessarily performed in the order described. For example, the cross-linking agent supply unit may be installed upstream of the foaming agent supply unit, and the foaming agent supply unit may be installed upstream of the cross-linking agent supply unit.

  The molten elastomer mixture reaches the reduced pressure part in the extruder, and foaming of the mixture starts to form a foam cell. Here, the crosslinking agent supply unit may be installed on the upstream side of the decompression unit, and the foaming of the mixture may proceed after the crosslinking of the mixture is started. Also, set the cylinder temperature appropriately so that crosslinking begins in the decompression section, or install a crosslinking agent supply section in the decompression section when the decompression section is in a sealed state, such as by devising a screw arrangement. Thus, the mixture may be crosslinked in the foaming stage (while foaming). Specifically, the mixture may be foamed after the crosslinking of the elastomer (A) forming the island phase is started, or the elastomer (A) forming the island phase may be crosslinked at the foaming stage of the mixture. . Thus, before the foam cell formation is completed, the elastomer (A) that forms the island phase is cross-linked so that the growth of the formed foam cell is controlled and the fine foam cell state is maintained. Become. In the present invention, it is particularly preferable that the foaming of the mixture proceeds after the crosslinking of the mixture (the elastomer (A) forming the island phase) is started.

  Usually, a step of continuously extruding the foamed molten elastomer composition obtained as described above from the die is performed. The foamed molten elastomer composition is discharged in an atmosphere whose pressure is relatively reduced as compared with that in the extruder. The die is also referred to as an extrusion die or extrusion head. As described above, the elastomer composition foam of the present invention can be produced.

  The pressure in a foaming agent supply part is 0.1-30 Mpa normally, Preferably it is 0.1-25 Mpa. On the other hand, the pressure in the decompression section is usually 0.1 to 10 MPa, preferably 0.1 to 1 MPa, and is set smaller than the pressure in the foaming agent supply section.

  Examples of the molding machine include conventionally known extruders such as a batch production apparatus, a single screw extruder, a twin screw extruder, a tandem extruder, a multi-screw extruder, an injection molding machine, an inflation molding machine, and a blow molding machine. Can be used. Among these, from the viewpoint of strengthening the kneading of the elastomer (A) and the thermoplastic resin (B), an extruder such as a twin screw extruder or a single screw extruder is preferable.

  What is necessary is just to set the maximum preset temperature of an extruder so that it may become the melt viscosity which can endure a melted elastomer composition, for example, 80-260 degreeC, for example, What is necessary is just to set to 140-230 degreeC. What is necessary is just to use the optimal screw according to the property of the foaming agent (D) to inject | pour as the screw of an extruder. When carbon dioxide (D1), nitrogen (D2), or the like is used as the foaming agent (D), the structure is not particularly limited as long as the raw material can be melted by the foaming agent supply unit.

  Next, although an example and a comparative example explain the present invention, the present invention is not limited to these examples and comparative examples. The following 1) to 5) are evaluation methods for the elastomer composition foams (hereinafter also referred to as “foamed elastomers”) obtained in Examples and Comparative Examples.

1) Cross-sectional observation The sample was cut to an appropriate size and then stained with RuO ₄ . After precision cutting again in the TD direction and chamfering, carbon deposition was performed. The sample was observed with a scanning electron microscope JSM-6380 (manufactured by JEOL Datum). Measurement conditions were performed at a voltage of 5 to 15 KV and a magnification of 2,000 to 10,000 depending on the sample.

2) Average cell diameter measurement The average value of the cell diameter about ten foamed cells selected at random from the observation photograph was made into the average cell diameter. When ten foamed cells could not be observed in one image, ten foamed cells were randomly selected from a plurality of images, and the average value of the cell diameters was calculated.

3) Calculation of the ratio of foamed cells having a cell diameter of less than 100 nm Cross-sectional SEM observation of the foamed elastomer is performed by the above method, and foamed cells having a cell diameter of less than 100 nm are calculated by 15 μm × 15 μm square and divided by the total number of foamed cells. And multiplied by 100.

4) Ratio measurement of cells formed in island phase In one of the above observation photographs, ρ _{A is} the cell density of cells formed in elastomer (A) which is an island phase, and thermoplasticity is a sea phase. When the cell density of the cells formed in the resin (B) is ρ _B , the value obtained by ρ _A / (ρ _A + ρ _B ) × 100 is defined as the cell ratio.

5) Density measurement Using an electronic densitometer (Mirage Co., Ltd., MD-200S), an average value for each density was measured when any three locations of the foamed elastomer were measured.

6) Measurement of tensile strength and measurement of tensile elongation The foamed elastomer was polished to a thickness of 2 mm, and the skin layer was removed to remove the influence of the skin layer. Thereafter, the sample was made to have a width of 5 mm, a tensile test was performed at a tensile speed of 500 mm / min, and the breaking strength (tensile strength) and the elongation at break (tensile elongation) were measured.

7) Intrinsic viscosity The intrinsic viscosity was measured in 135 ° C decalin (decahydronaphthalene).

[Example 1]
A foamed elastomer 4 was produced by the apparatus configuration shown in FIG. That is, using a twin screw extruder (L / D = 81.6) having a screw diameter of 30 mm as the extruder 1, the foamed elastomer 4 was produced.

As the elastomer (A), ethylene / propylene / 5-ethylidene-2-norbornene copolymer rubber (ethylene content = 80 mol%, propylene content = 20 mol%, iodine value = 12, [η] = 3.5 dl / g, 60 parts by weight of density 0.87 g / cm ³ ), 40 parts by weight of propylene homopolymer ([η] = 2.4 dl / g, density 0.91 g / cm ³ ) as thermoplastic resin (B), and further inorganic filling As an agent (E), 3 parts by weight of calcium carbonate (produced by Calfine; MD-2-5) was sufficiently dry blended and charged from the hopper 6. At this time, the set temperature of the extruder 1 was 190 ° C., and the screw rotation speed was 300 rpm.

A mixed solution 12 of 0.2 parts by weight of peroxide as a crosslinking agent (C) and 5 parts by weight of process oil as a softening agent (F) was supplied to the extruder 1 through a pump 13. At this time, the pressure inside the cross-linking agent supply unit 14 was 8 MPa. However, the peroxide is manufactured by Nippon Oil &Fats; Park Mill D (dicumyl peroxide), 1 minute half-life temperature 175.2 ° C., molecular weight 270.38, and process oil is manufactured by Idemitsu Kosan; PW-90, density 0 .87 g / cm ³ . The supply amount of peroxide and process oil was based on a total of 100 parts by weight of the elastomer (A) and the thermoplastic resin (B). The cross-linking agent supply unit 14 is such that the time until the elastomer (A) that has passed 14 reaches the vacuum vent 15 (decompression unit) is shorter than the time (0.5 minutes or less) in which the cross-linking agent (C) is halved. It was installed in a proper position.

  A siphon-type liquefied carbon dioxide cylinder 7 was used so that carbon dioxide could be directly taken out from the liquid phase portion as a foaming agent (D). The flow path from the liquefied carbon dioxide cylinder 7 to the carbon dioxide metering pump 9 is cooled with an ethylene glycol aqueous solution adjusted to −12 ° C. by the refrigerant circulator 8, and the carbon dioxide is sent to the carbon dioxide metering pump 9 in a liquid state. I was able to liquid.

  Next, the discharge pressure of the carbon dioxide metering pump 9 was adjusted by the pressure holding valve 10, and carbon dioxide was supplied into the extruder 1. At this time, the pressure inside the carbon dioxide supply unit 11 was 8 MPa. In this manner, carbon dioxide was supplied to the extruder 1 at a ratio of 10 parts by weight with respect to a total of 100 parts by weight of the elastomer (A) and the thermoplastic resin (B), and was uniformly dissolved and diffused by the screw. .

  Next, while deaeration was performed using the vacuum vent 15, the pressure in this part was 1 MPa or less. By reducing the pressure in this manner, the foaming agent (D) dissolved in the elastomer (A) and the thermoplastic resin (B) is saturated, and foamed cells are formed.

  When the crosslinking agent (C) is not added, the formed foam cell disappears inside the extruder 1. On the other hand, when the cross-linking agent (C) is added, since the formed foam cell is mainly surrounded by the cross-linked elastomer (A), the cell passes through the die 3 while maintaining its state. Then, the foamed elastomer 4 is collected.

The average cell diameter of the foamed cells in the obtained foamed elastomer 4 is 370 nm, and the ratio of the foamed cells having a cell diameter of less than 100 nm among the foamed cells is 46% on the basis of the number, and the cells formed in the island phase Of the foamed elastomer 4 was 0.68 g / cm ³ , the tensile strength was 15 MPa, and the tensile elongation was 95%.

[Example 2]
Example 1 except that the cross-linking agent supply unit 14 was installed at a position where the time until the elastomer (A) that passed through 14 reached the vacuum vent 15 was three times the time that the cross-linking agent (C) was halved. As well as.

Example 3
As a crosslinking agent (C), instead of the above peroxide, an alkylphenol formaldehyde resin (trade name “Tackol 201”, manufactured by Taoka Chemical Co., Ltd.) is heated to 80 ° C. and softened, and an elastomer (A) and a thermoplastic resin are used. The same procedure as in Example 1 was performed, except that it was used at a ratio of 2 parts by weight to 100 parts by weight in total with (B).

Example 4
As a crosslinking agent (C), instead of the above peroxide, (CH ₃ ) ₃ SiO — [— SiH (CH ₃ ) —O—] ₆ — [— Si (CH ₃ ) ₂ —O—] ₁ — [— Si (C ₆ H ₆ ) ₂ —O—] ₁ —Si (CH ₃ ) ₃ is used at a ratio of 4 parts by weight with respect to a total of 100 parts by weight of the elastomer (A) and the thermoplastic resin (B), Platinum-1,3,5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasiloxane complex as catalyst: 1,3,5,7-tetravinyl at 2% platinum (zero valent) concentration 1,3,5,7-tetramethylcyclotetrasiloxane complex-IPA (isopropyl alcohol) solution [N, manufactured by Echem Cat Co., Ltd.], 100 weight total of elastomer (A) and thermoplastic resin (B) Used at a ratio of 0.075 parts by weight with respect to parts. It was carried out in the same manner as in Example 1.

Example 5
As the blowing agent (D), nitrogen is used instead of carbon dioxide at a ratio of 10 parts by weight with respect to a total of 100 parts by weight of the elastomer (A) and the thermoplastic resin (B). Example 1 was carried out in the same manner as in Example 1 except that the gas was supplied directly from a cylinder through a control valve installed in

Example 6
As foaming agent (D), instead of carbon dioxide, azodicarbonamide / 4,4'-oxybis (benzenesulfonylhydrazide) (ADCA / OBSH) composite foaming agent (manufactured by Eiwa Chemical Industry Co., Ltd., Spancel DS-25) ) Was used at a ratio of 0.5 part by weight with respect to 100 parts by weight of the total of the elastomer (A) and the thermoplastic resin (B), and was carried out in the same manner as in Example 1 except that it was supplied from the hopper.

Example 7
The same procedure as in Example 1 was carried out except that 40 parts by weight of a propylene random copolymer ([η] = 2.4 dl / g, density 0.91 g / cm ³ ) was used as the thermoplastic resin (B).

Example 8
The same procedure as in Example 1 was performed except that 40 parts by weight of a propylene block copolymer ([η] = 3.5 dl / g, density 0.91 g / cm ³ ) was used as the thermoplastic resin (B).

Example 9
Example 1 except that 5 parts by weight of naphthenic process oil (manufactured by Nippon San Oil; Sansen 4240) was used as the softening agent (F) with respect to 100 parts by weight in total of the elastomer (A) and the thermoplastic resin (B). As well as.

Example 10
Ethylene / propylene / 5-ethylidene-2-norbornene copolymer rubber (ethylene content = 80 mol%, propylene content 20 mol%, iodine value = 12, [η] = 4.5 dl / g, density as elastomer (A) The same procedure as in Example 1 was performed except that 60 parts by weight of 0.87 g / cm ³ ) was used.

[Comparative Example 1]
The same procedure as in Example 1 was conducted except that the crosslinking agent (C) was not used.

[Comparative Example 2]
The same procedure as in Example 1 was performed except that the cross-linking agent supply unit 14 was installed on the downstream side of the vacuum vent 15 and the cross-linking was started after foam cell formation was completed.

[Comparative Example 3]
The same procedure as in Example 1 was performed except that the amount of the elastomer (A) used was 95 parts by weight and the amount of the thermoplastic resin (B) used was 5 parts by weight.

[Comparative Example 4]
The same procedure as in Example 1 was performed except that the amount of the elastomer (A) used was 5 parts by weight and the amount of the thermoplastic resin (B) used was 95 parts by weight.

[Comparative Example 5]
The same operation as in Example 1 was carried out except that the inorganic filler (E) was not used.
The evaluation results in the above examples and comparative examples are shown in Table 1.

DESCRIPTION OF SYMBOLS 1 Extruder 2 Screw 3 Die 4 Foam elastomer 5a Elastomer (A)
5b Thermoplastic resin (B)
5c Inorganic filler (E)
6 Hopper 7 Liquefied carbon dioxide cylinder 8 Refrigerant circulating machine 9 Carbon dioxide metering pump 10 Holding pressure valve 11 Carbon dioxide supply unit 12 Mixed solution of cross-linking agent (C) and softening agent (F) 13 Pump 14 Cross-linking agent supply unit 15 Vacuum Bento

Claims (25)

10 to 90 parts by weight of the elastomer (A) and 10 to 90 parts by weight of the thermoplastic resin (B) (however, the total of (A) and (B) is 100 parts by weight) are melt mixed to form a mixture. And having a foamed cell having an average cell diameter of 50 to 3000 nm as measured by a scanning electron microscope (SEM) obtained by crosslinking and foaming the mixture, and foaming having a cell diameter of less than 100 nm among the foamed cells. An elastomer composition foam having a cell ratio of 30% or more on a number basis and a density of 0.01 to 0.85 g / cm ³ .   The crosslinker (C) is used in a proportion of 0.01 to 50 parts by weight with respect to a total of 100 parts by weight of the elastomer (A) and the thermoplastic resin (B). Item 2. The elastomer composition foam according to Item 1.   The crosslinking agent (C) is selected from a SiH group-containing compound (C1) having at least two SiH groups in one molecule, an organic peroxide (C2), and a phenol-based resin (C3). Item 3. The elastomer composition foam according to Item 2.   It is obtained by using the foaming agent (D) at a ratio of 0.1 to 200 parts by weight with respect to 100 parts by weight of the total of the elastomer (A) and the thermoplastic resin (B). Item 4. The elastomer composition foam according to any one of Items 1 to 3.   The elastomer composition foam according to claim 4, wherein the foaming agent (D) is selected from carbon dioxide (D1), nitrogen (D2) and a chemical foaming agent (D3).   It is obtained by using an inorganic filler (E) in a proportion of 0.01 to 100 parts by weight with respect to a total of 100 parts by weight of the elastomer (A) and the thermoplastic resin (B). The elastomer composition foam according to any one of claims 1 to 5.   The softening agent (F) is used at a ratio of 1 to 150 parts by weight with respect to a total of 100 parts by weight of the elastomer (A) and the thermoplastic resin (B). The elastomer composition foam as described in any one of -6.   The elastomer (A) is an ethylene / α-olefin copolymer rubber composed of ethylene and an α-olefin having 3 to 20 carbon atoms, and ethylene, an α-olefin having 3 to 20 carbon atoms and a non-conjugated polyene The elastomer composition foam according to any one of claims 1 to 7, which is at least one selected from ethylene / α-olefin / non-conjugated polyene copolymer rubber.   The elastomer composition foam according to claim 8, wherein the elastomer (A) is an ethylene / propylene / non-conjugated polyene copolymer rubber.   The thermoplastic resin (B) is a (co) polymer obtained by (co) polymerizing an α-olefin having 2 to 20 carbon atoms. The elastomer composition foam according to item.   The thermoplastic resin (B) is at least one selected from a propylene homopolymer and a copolymer of propylene and an α-olefin having 2 to 20 carbon atoms (excluding propylene) mainly composed of propylene. The elastomer composition foam according to claim 10, wherein the foam is an elastomer composition foam.   It has a sea island structure containing the sea phase formed from the said thermoplastic resin (B), and the island phase formed from the said elastomer (A), It is any one of Claims 1-11 characterized by the above-mentioned. Elastomer composition foam.   The elastomer composition foam according to any one of claims 1 to 12, wherein cells are selectively formed in an island phase formed from the elastomer (A).   It is obtained by foaming the mixture after the crosslinking of the elastomer (A) forming the island phase is started, or by crosslinking the elastomer (A) forming the island phase in the foaming stage of the mixture. The elastomer composition foam according to claim 12 or 13. 10 to 90 parts by weight of the elastomer (A) and 10 to 90 parts by weight of the thermoplastic resin (B) (however, the sum of (A) and (B) is 100 parts by weight) and the crosslinking agent (C) 0 An average cell diameter measured by a scanning electron microscope (SEM) is 50 to 50, characterized by comprising a step of melt-mixing 0.01 to 50 parts by weight to form a mixture, and crosslinking and foaming the mixture. Elastomer composition having a foam cell of 3000 nm, a ratio of a foam cell having a cell diameter of less than 100 nm of the foam cell of 30% or more on a number basis, and a density of 0.01 to 0.85 g / cm ³ A method for producing a foam.   The elastomer composition foam according to claim 15, wherein the mixture is foamed after the crosslinking of the elastomer (A) is started, or the elastomer (A) is crosslinked in a foaming stage of the mixture. Production method.   The crosslinking agent (C) is selected from a SiH group-containing compound (C1) having at least two SiH groups in one molecule, an organic peroxide (C2), and a phenol-based resin (C3). Item 17. A method for producing an elastomer composition foam according to Item 15 or 16.   The foaming agent (D) is used in a ratio of 0.1 to 200 parts by weight with respect to a total of 100 parts by weight of the elastomer (A) and the thermoplastic resin (B). The method for producing an elastomer composition foam according to any one of 17.   The method for producing an elastomer composition foam according to claim 18, wherein the foaming agent (D) is selected from carbon dioxide (D1), nitrogen (D2), and a chemical foaming agent (D3).   The inorganic filler (E) is used in a proportion of 0.01 to 100 parts by weight with respect to a total of 100 parts by weight of the elastomer (A) and the thermoplastic resin (B). The manufacturing method of the elastomer composition foam as described in any one of -19.   The softener (F) is used in a proportion of 1 to 150 parts by weight with respect to 100 parts by weight of the total of the elastomer (A) and the thermoplastic resin (B). The manufacturing method of the elastomer composition foam as described in any one of Claims.   The elastomer (A) is an ethylene / α-olefin copolymer rubber composed of ethylene and an α-olefin having 3 to 20 carbon atoms, and ethylene, an α-olefin having 3 to 20 carbon atoms and a non-conjugated polyene The method for producing an elastomer composition foam according to any one of claims 15 to 21, which is at least one selected from ethylene / α-olefin / non-conjugated polyene copolymer rubber.   The thermoplastic resin (B) is a (co) polymer obtained by (co) polymerizing an α-olefin having 2 to 20 carbon atoms. The manufacturing method of the elastomer composition foam of description.   24. It has a sea-island structure including a sea phase formed from the thermoplastic resin (B) and an island phase formed from the elastomer (A). A process for producing an elastomer composition foam.   The method for producing an elastomer composition foam according to any one of claims 15 to 24, wherein cells are selectively formed in an island phase formed from the elastomer (A).

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