JPH07330935A - Crystalline polyolefin foam - Google Patents

Abstract

PURPOSE:To obtain a crystalline polyolefin foam having a preferable expansion ratio and a higher closed-cell percentage by incorporating a specific amount of a crystalline polyolefin and a specific amount of fibrous polytetrafluoroethylene. CONSTITUTION:This crystalline polyolefin foam contains 100 pts.wt. crystalline polyolefin and 0.001 to 10 pts.wt. fibrous polytetrafluoroethylene. It is preferred that the polytetrafluoroethylene be fine powder obtained by allowing an emulsified dispersion of polytetrafluoroethylene formed by an emulsion polymerization to agglomerate. Desirably, the crystalline polyolefin foam is obtained by a process wherein polytetrafluoroethylene and dispersion medium powder with an average particle size of 5o to 700mum are mixed in advance under a high shearing stress to fibrillate the polytetrafluoroethylene, followed by mixing the resultant mixture with a crystalline polyolefin. As the dispersion medium powder, polyolefin powder is preferable.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crystalline polyolefin foam containing a crystalline polyolefin and a fibrous material of polytetrafluoroethylene.

[0002]

2. Description of the Related Art Crystalline polyolefins are widely used for various molded products because they are inexpensive and have excellent physical properties. However, for example, polypropylene is difficult to produce a foam because of its low viscosity and low tension when melted.

In order to solve this point, for example, Japanese Patent Laid-Open No. 62-121704 proposes a technique for branching polypropylene by radiation. Further, JP-A-2-298536 proposes a method for producing a branched polypropylene using a peroxide. In addition, Japanese Patent Publication No. 5-506875 (US Pat.
No. 41) proposes a foamed sheet using these.

Further, Japanese Patent Publication No. 43-3993 proposes to obtain a sheet-like foam having a high expansion ratio by combining an activating liquid such as methylene chloride with a volatile foaming agent.

[0005]

The technique using the branched polypropylene has a major drawback such as an increase in the number of manufacturing processes, and also has a drawback that it is difficult to recycle due to the presence of the branched polypropylene.

Further, the technique disclosed in Japanese Patent Publication No. 43-3993 is required to use methylene chloride or the like, and this treatment has a problem.

As mentioned above, a crystalline polyolefin foam has not yet been obtained by a problem-free method.

It is an object of the present invention to provide a crystalline polyolefin foam useful in a method that does not have the above problems. In particular, the object is to easily provide a useful polypropylene foam.

[0009]

According to the present invention, 100 parts by weight of crystalline polyolefin (A) (parts by weight, the same applies hereinafter) and fibrous substance of polytetrafluoroethylene (B) 0.001
It relates to a crystalline polyolefin foam containing 10 parts. In addition, 100 parts of the crystalline polyolefin (A) and 0.001 of the fibrous material of polytetrafluoroethylene (B)
It also relates to a crystalline polyolefin foam containing -10 parts and 0.001-2 parts of a nucleating agent (C).

[0010]

The present invention relates to a crystalline polyolefin foam containing 100 parts of crystalline polyolefin (A) and 0.001 to 10 parts of a fibrous material of polytetrafluoroethylene (B).

The foam of the present invention comprises the crystalline polyolefin (A) (hereinafter also referred to as polyolefin (A)) and polytetrafluoroethylene (B) (hereinafter PTF).
It can be obtained by a foam molding method using a polyolefin resin composition (hereinafter also referred to as a PO composition) containing a fibrous material of E (B).

Examples of the polyolefin (A) include homopolypropylene, high-density polyethylene, low-density polyethylene, linear low-density polyethylene, poly-1-butene, polyisobutylene, polypropylene copolymers such as propylene and ethylene and (or ) Random or block copolymers in all proportions with 1-butene, ethylene-propylene-diene terpolymers containing up to 50% (wt%, the same below) of diene components in all proportions of ethylene and propylene. , Polymethylpentene, copolymers of cyclopentadiene and ethylene or propylene, and other cyclic polyolefins,
Examples thereof include random, block or graft copolymers of ethylene or propylene with 50% or less of vinyl compounds such as vinyl acetate, methacrylic acid alkyl ester, acrylic acid alkyl ester, aromatic vinyl and the like.

These may be used alone or in admixture of two or more.

Among the polyolefins (A), a propylene-based polyolefin obtained by polymerizing a monomer component containing 50% or more, and further 75% or more of propylene or propylene containing 50% or more of propylene. 100 parts of polyolefin and 5 parts of ethylene
Ethylene-based polyolefin containing 0% or more 0.1-1
A mixture with 00 parts is preferable because of high melt tension and versatility.

Further, among the above polyolefins (A), when the polyolefin (A) is at least one selected from homopolypropylene, ethylene propylene random copolymer and ethylene propylene block copolymer, it is more preferable. It is preferable because it has versatility, low cost, and easy recycling.

Further, among the above-mentioned crystalline polyolefins, homopolypropylene is most preferable from the viewpoint of strength and heat resistance of the obtained crystalline polyolefin foam.

The polyolefin (A) has a melt flow index (hereinafter also referred to as MI) of 0.
3 to 10 and more preferably 0.4 to 8 are preferable. MI is 0.3
Smaller ones may make the flow difficult at the time of melting to make molding difficult, and more than 10 may have less effect of improving tension at melting when polytetrafluoroethylene (B) is added. Tend. In addition, MI is
1 according to ASTM D1238 with a load of 2.16 kg
It is a value obtained by measuring the number of grams of molten polymer falling in 0 minutes. In addition, it is 230 for propylene-based polyolefin.
℃, the value at 190 ℃ for ethylene-based polyolefin.

The foam of the present invention contains a fibrous material of PTFE (B) in addition to the polyolefin (A). The fibrous material is a component that exhibits the effect of increasing the tension at the time of melting and the effect of promoting crystallization, and makes it easy to obtain the foam of the present invention.

The PTFE (B) is not particularly limited as long as it is made into fibers by applying a shearing force,
Examples include powders produced by aggregating an emulsion dispersion of high molecular weight polytetrafluoroethylene obtained by emulsion polymerization, powders produced from high molecular weight polytetrafluoroethylene obtained by suspension polymerization, etc. .

Among them, fine powder produced by aggregating an emulsion dispersion of high molecular weight polytetrafluoroethylene obtained by an emulsion polymerization method,
It is preferable because it is soft and easily broken, and is easily made into fibers by shearing force. Even if the powder of polytetrafluoroethylene does not become fibrous due to the difference in the synthesis method, it does not exhibit the effect of increasing the tension during melting and is not used in the present invention.

The average particle size of the PTFE (B) is 100 to 700 μm, preferably 300, from the viewpoint of mixing and dispersion with the dispersion medium powder (C) described later by master batching.
.About.600 microns, more preferably 400 to 500 microns.

Commercially available raw materials for obtaining PTFE (B) fibrous materials include Polyflon TFE-F103 and F104 manufactured by Daikin Industries, Ltd. and Teflon TFE-6J and 6C-J manufactured by Mitsui DuPont. Typical examples are as follows.

In the present invention, the fibrous material of PTFE (B) is 0.001 with respect to 100 parts of the polyolefin (A).
-10 parts included. The fibrous material of PTFE (B) is 0.0
If the amount is less than 01 part, the effect of increasing the tension during melting and the effect of promoting crystallization are not sufficient, and if the amount exceeds 10 parts, a cost problem arises when uniform mixing cannot be achieved. From this point, the minimum content of PTFE (B) is preferably 0.05 parts, more preferably 0.1 parts, and the maximum content is preferably 5 parts and further 3 parts.

The fibrous material of PTFE (B) means PTFE
There is no particular limitation as long as (B) is in a fibrous state. For example, in the foam of the present invention or in the PO composition, the fiber diameter of PTFE (B) has an efficient network structure. It is preferably about 2 microns or less, more preferably about 1 micron or less, and even more preferably about 0.5 micron or less. The fiber length is
Since it has a network structure, it cannot be generally stated, but it is preferably about 3 μm or more, more preferably about 5 μm or more, and further preferably about 10 μm or more, from the viewpoint of the effect of increasing the tension during melting and the effect of promoting crystallization. .

The method of fiberizing PTFE (B) is not particularly limited, but for example, a method of kneading and mixing the powder or pellets of PTFE (B) and polyolefin (A) with a kneading machine such as a twin-screw extruder that is subject to shearing. , PTFE
There is a method of mixing (B) and the dispersion medium powder (C). The method of stirring and mixing or kneading and mixing the PTFE (B) and the dispersion medium powder (C) is preferable because the PTFE (B) can be efficiently made into fibers and dispersed. A PO composition can be obtained by mixing the obtained kneaded mixture or stirred mixture with the polyolefin (A). The mixing method is not particularly limited, and it can be produced by a usual method such as an extrusion mixing method and a roll mixing method. Since the fibrous substance of PTFE (B) is efficiently dispersed in the polyolefin (A) in the PO composition,
It is possible to prevent uneven foaming and reduce the amount of PTFE (B) added.

Among the methods of stirring and mixing the above-mentioned PTFE (B) and dispersion medium powder (C), PTFE (B)
And a dispersion medium powder (C) having an average particle diameter of 50 to 700 microns are mixed in advance under high shear to obtain PTFE (B).
It is preferable to use a method in which the resin is made into fibers and then mixed with the polyolefin (A). According to this method, the fibrous material of PTFE (B) can be efficiently dispersed in the polyolefin (A), the effect of increasing the tension during melting and the effect of promoting crystallization are exhibited, and the excellent foaming of the present invention is achieved. You can get your body.

The dispersion medium powder (C) is PTFE (B)
Is not particularly limited as long as it can effectively disperse and fiberize, for example, core-shell graft copolymer, polyolefin powder, inorganic powder,
There are organic powders and the like, and these can be used alone or in admixture of two or more. Among the dispersion medium powders, core-shell graft copolymers are preferable from the viewpoint of increasing tension at melting and dispersibility of polytetrafluoroethylene, and the dispersion medium powder (C) itself has low dispersibility in the polyolefin (A) and low dispersibility. From the viewpoint of cost, polyolefin powder is preferable.

The dispersion medium powder (C) has an average particle size of 5
When the average particle size is 0 to 700 μm and the average particle size is less than 50 μm or exceeds 700 μm, the polytetrafluoroethylene is not sufficiently fiberized, and the obtained P
A lump of PTFE (B) remains on the molded product from the O composition, and the surface property deteriorates. Further, the workability improving effect is also insufficient. From the above viewpoint, it is preferable that the minimum value of the average particle diameter is 70 μm, further 100 μm, and the maximum value is 500 μm, further 300 μm.

The average particle size of the dispersion medium powder (C) is such that Tyler meshes of about 6 different sizes are stacked in order from the largest mesh size, and a powder dispersed in water using a surfactant is poured onto the Tyler meshes. Although it is calculated from the weight ratio of the accumulated powder by a particle size diagram, it can be measured by other general powder measuring methods.

The average particle diameter of the dispersion medium powder (C) is 50 to 50.
The method for controlling the particle size to 700 μm is not particularly limited, but in general, any method for controlling the particle size of the powder such as agglomeration, pulverization and sieving can be used. For example, in the case of core-shell graft copolymer, the particle size of powder can be controlled by the agglomeration method. In the case of a polyolefin powder, a powder having a suitable particle size can be obtained by controlling the particle size at the time of polymerization and the conditions at the time of freeze-grinding. In the case of inorganic powder, there are methods such as crushing and sieving.

The core-shell graft copolymer (hereinafter also referred to as the core-shell body) used for the dispersion medium powder (C) is
In the presence of a cross-linked rubber-like polymer forming the core layer, the shell component is obtained by graft copolymerization, which may be one generally used for improving impact resistance such as polyolefin and polyvinyl chloride. . Among the core-shell bodies, those not thermally deteriorated at the molding and processing temperature of the polyolefin (A) are preferable from the viewpoint of heat coloring of the foam made of the PO composition obtained.

The powder of the core-shell body can be controlled to have a particle size when agglomerated, and it is easy to obtain the powder having the particle size suitable for the present invention. Commercially available core-shell type modifiers are Kanefuchi Chemical Co., Ltd. product names: Kane Ace B, Kane Ace M, Kane Ace FM
And the like are preferred.

Specific examples of the polyolefin powder used as the dispersion medium powder (C) include homopolypropylene, high density polyethylene, low density polyethylene, linear low density polyethylene, poly-1-butene, polyisobutylene, polypropylene copolymer. For example, random or block copolymers of propylene with ethylene and / or 1-butene in any ratio, ethylene-propylene-diene terpolymers containing 50% or less of diene component in any ratio of ethylene with propylene. , Polymethylpentene, copolymers of cyclopentadiene with ethylene or propylene and other cyclic polyolefins, ethylene or propylene with 50% or less of vinyl acetate, methacrylic acid alkyl ester, acrylic acid alkly Esters, random such as vinyl compounds such as aromatic vinyl, such as block or graft copolymer.

These may be used alone or in admixture of two or more.

Among the above polyolefin powders,
The propylene-based polyolefin obtained by polymerizing the monomer component containing 50% or more of propylene is preferable from the viewpoint of versatility and low cost.

Further, 100 parts of the propylene-based polyolefin containing 50% or more of the propylene, and 0.1 part of the ethylene-based polyolefin containing 50% or more of the ethylene.
A mixture with ˜100 parts is preferable from the viewpoint of high melt tension.

Specific examples of the inorganic powder used for the dispersion medium (C) include heavy calcium carbonate, light calcium carbonate, talc, glass fiber, magnesium carbonate, mica, carion, calcium sulfate, barium sulfate, titanium white and white. Examples thereof include carbon, carbon black, aluminum hydroxide, aluminum oxide, magnesium hydroxide, fused silica, etc., which may be used alone or in combination with 2
A mixture of two or more species can be used. Among these, heavy calcium carbonate, light calcium carbonate, talc and the like are preferable because they are easily available.

Similarly, as the organic powders, there are thermoplastic elastomers represented by block or random copolymers of styrene and butadiene and their hydrogenated products, crosslinked elastomers represented by polybutadiene and their hydrogenated products, and the like. As a representative example. Among these, those having a certain degree of compatibility with the polyolefin (A) and having an average particle diameter of the powder falling within the range of the present invention and freeze-pulverized so as to fall within the range are preferable. .

The dispersion medium powder (C) is the same as that of PTFE.
It is preferable that the mixture with (B) and the polyolefin (A) can be easily mixed. If mixing is not easy, it tends to deteriorate homogenization of foaming and open cells. In order to facilitate mixing, the dispersion medium powder (C) such as polyolefin powder and the polyolefin (A) preferably have the same melt flow index.

Further, it is preferable that the polyolefin powder and the polyolefin (A) have substantially the same composition from the viewpoint of easy mixing and homogenization of foaming.

The dispersion medium powder (C) and PTFE
Ratio (C) / (B) with (B) is 100/50 to 100
The range of /0.001 is preferable. The ratio is 100 /
When it is less than 50, the fiberization of PTFE (B) is not sufficiently performed, and the polyolefin (A) of PTFE (B) is not formed.
And the effect of the present invention is reduced. When the ratio exceeds 100 / 0.001, for example, even if 0.001 part of PTFE (B) is mixed with 100 parts of polyolefin (A), the dispersion medium powder (C) is 10 parts.
It is not preferable because it exceeds 0 part. From the above viewpoint, the minimum value of the ratio (C) / (B) is preferably 100/20,
More preferably, it is 100/10, and similarly, the maximum value is preferably 100 / 0.002, more preferably 100 / 0.005.

Pre-mixed under high shear as above and added
Making (B) into fibers means, for example, by applying shearing force in advance by a powder mixing method such as stirring the dispersion medium powder (C) and PTFE (B) using a Henschel mixer or other general agitator. Dispersing and fiberizing (B).

The operating conditions for preparing the mixture by the powder mixing method are not particularly limited as long as PTFE (B) can be mixed under high shear to form fibers.

As a temperature condition for preparing a stirred mixture by a powder mixing method using a Henschel mixer or the like, stirring may be carried out at room temperature, and the dispersion medium powder (C) and PTFE (B) are not deteriorated or deteriorated. You may heat and stir at about temperature.

It is also possible to melt-knead and pelletize after the powder mixing method. For example, it is also preferable that after mixing with a Henschel mixer, a part of the polyolefin (A) is added to the mixture or the mixture and the mixture is melt-kneaded with an extruder or the like to be pelletized to prepare a stirring / kneading mixture.

The present invention further relates to polyolefin (A) 1
00 parts and PTFE (B) fibrous material 0.001-1
It also relates to a crystalline polyolefin foam further containing 0.001 to 2 parts of a nucleating agent (D) in 0 part.

The nucleating agent (D) is a component capable of imparting foamability and / or controlling cell size by shortening crystallization time.

Specific examples of the nucleating agent used in the present invention include, for example, sodium benzoate, bisbenzylidene sorbitol, bis (p-methylbenzylidene) sorbitol, bis (p-ethylbenzylidene) sorbitol, sodium 2,2- Methylenebis (4,6-di-tert-butylphenyl) phosphite, talc,
TiO2, silica, silicate, zeolite 4A, sodium benzoate, citric acid-sodium bicarbonate blend, aluminum hydroxydipara t-butyl benzoate and the like. These may be used alone or in combination of two or more.

The amount of the nucleating agent used is preferably 0.001 to 2 parts with respect to 100 parts of the polyolefin (A). If the content of the nucleating agent is less than 0.001 part, the effect of improving foamability and control of cell size tends to be insufficient, and if it exceeds 2 parts, the effect is saturated. However, there is a cost problem, which is not preferable.

In the foam of the present invention, an inorganic filler may be added if necessary. Such inorganic filler (E)
As typical examples of, heavy calcium carbonate, light calcium carbonate, talc, glass fiber, magnesium carbonate, mica, carion, calcium sulfate, barium sulfate, titanium white, white carbon, carbon black, aluminum hydroxide, aluminum oxide, water Magnesium oxide, fused silica, etc. may be mentioned, either alone or in combination with 2.
A mixture of two or more species can be used. Among these, heavy calcium carbonate, light calcium carbonate, talc and the like are preferable because they are easily available.

The foam of the present invention may further contain, for example, stabilizers and lubricants, if necessary. Examples of the stabilizer include pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] and triethylene glycol-bis [3- (3-t-butyl-5-methyl). -4-hydroxyphenyl) propionate] and other phenolic stabilizers, tris (monononylphenyl) phosphite, tris (2,4-di-t-butylphenyl) phosphite and other phosphorus stabilizers, and dilauryl 3,3. As sulfur-based stabilizers such as ′ -thiodipropionate, and lubricants,
Representative examples thereof include lauric acid, palmitic acid, oleic acid, stearic acid sodium salt, calcium salt, and magnesium salt.

In the present invention, the method of mixing the agitated mixture or kneaded mixture with the polyolefin (A) and, if necessary, the nucleating agent (D), the inorganic filler or the like is not particularly limited and, for example, extrusion mixing is used. It can be produced by an ordinary method such as a method and a roll mixing method.

In addition, after mixing the agitated mixture or the kneaded mixture with a part of the polyolefin (A), and in some cases, with the nucleating agent (D), the rest of the mixture is mixed with the polyolefin (A). Mixing is also possible.

The crystalline polyolefin foam of the present invention comprises
It can be obtained by performing foam molding using the PO composition and the foaming agent.

The foaming agents used in the present invention can be roughly classified into volatile type foaming agents and decomposition type foaming agents.
A volatile foaming agent is preferred from the viewpoint of increasing the foaming ratio of the foamed product.

As the volatile type foaming agent, aliphatic hydrocarbons, chlorinated products or fluorinated products thereof are generally used. Examples of the aliphatic hydrocarbon include propane, butane,
Examples include pentane, hexane and their isomers. Examples of the chlorinated aliphatic hydrocarbon include methyl chloride and methylene dichloride. Examples of the fluorinated aliphatic hydrocarbon include trichloromonofluoromethane (Freon-11), dichlorodifluoromethane (Freon-12) and dichlorotetrafluoroethane (Freon-).
114) is a typical example. These are used alone or in combination of two or more. Of these, aliphatic hydrocarbons are most preferable due to recent environmental problems.

As the decomposition type foaming agent, azodicarbonamide, trihydrazinotriazine, benzenesulfonisemicarbazide, diazoaminobenzene, N, N'-dinitrosopentamethylenetetramine, N, N'-dimethyl-
Examples thereof include N, N'-dinitroterephthalimide, barium azodicarboxylic acid, p, p'-oxybisbenzenesulfonyl hydrazide and the like.

The proportion of the PO composition and the foaming agent used is generally 1 to 50 parts of the foaming agent per 100 parts of the PO composition in view of the expansion ratio, the stability of the foam, and the surface property of the molded article. The range is 5 to 40 parts.

As the foaming molding method, a molding method which has been generally used conventionally, such as an extrusion foaming molding method, a bead foaming molding method, or an atmospheric pressure foaming molding method can be used. Among these, the extrusion foam molding method is preferable from the viewpoint of foam productivity, and the bead foam molding method is preferable from the viewpoint of high foaming. The foam obtained by the extrusion foam molding method is low in cost, and the foam obtained by the bead foam molding method has excellent dimensional accuracy and appearance.

In the case of molding by extrusion foam molding method, for example, various uniaxial or biaxial equipped with pellets of the PO composition and a foaming agent having dies having various shapes according to the purpose of the molded article. Using an extruder, the molding temperature is higher than the melting point of the polyolefin (A) or higher than the decomposition temperature when a decomposition type foaming agent is used, and it is preferable to set the temperature of the die lower than the temperature at the tip of the cylinder. preferable.

The foam thus obtained has a foaming ratio of 2 to 10 times, further 3 to 8 times, and can be used for heat insulating materials, building materials, structural materials and the like.

In the case of molding by the bead foam molding method, for example, the pellets of the PO composition and the volatile foaming agent are enclosed in a closed container and kept at a predetermined temperature (usually 20 to 90).
C.) is maintained for a predetermined time (usually 5 to 20 hours) to impregnate the volatile foaming agent. After impregnation, take out the pellets from the closed container and heat them with steam, hot water or hot air,
Pre-expansion is performed to obtain pre-expanded particles.

The obtained pre-expanded particles can be filled in, for example, a mold having water vapor passage holes and heated in an autoclave to obtain a foam.

The foam thus obtained has a foaming ratio of 10 to 60 times, more preferably 15 to 45 times, and can be used for heat insulating materials, cushioning materials, bumper core materials and the like.

As the above-mentioned crystalline polyolefin foam containing a nucleating agent, a thermoforming sheet is preferable from the viewpoint of easy control of cell size. Thermoforming sheets are manufactured by extrusion foaming, by extrusion from a slot die, which is vacuum formed,
Used for secondary processing such as pressure forming.

The foam of the present invention will be described in more detail based on the following examples, but the present invention is not limited thereto.

Examples 1 to 10 and Comparative Examples 1 to 7 Table 1 and Table 2 of the dispersion medium powder (C) described in Tables 1 and 2 and Table 1 of the powder of PTFE (B) described in Tables 1 and 2. ,
2 With the Henschel mixer, stir at high speed for 5 minutes at room temperature, mix and shear to add PTFE
(B) was fiberized to prepare a mixture under high shear.

The amount of the obtained mixture under high shearing described in Tables 1 and 2 and 100 parts of the polyolefin (A) described in Tables 1 and 2 were mixed with a single-screw extruder having a screw diameter of 50 mm and an L / D of 28.
Extruded and kneaded at 80 ° C and 50 rpm, pelletized and PO
The composition was obtained.

A screw diameter of 40 mm-5 was applied to this pellet.
Using a 0 mm (rotation speed 70/20 rpm) tandem extruder, isorich butane as a foaming agent was extruded and foamed from a 0.6 mm slit die (temperature of about 160 ° C.) at a discharge rate of 9 kg / hr to form a board-shaped foam. I got it. The foaming agent is PO
3 parts were used per 100 parts of the composition.

Example 5 is an example in which 0.1 part of citric acid-sodium bicarbonate as a foam nucleating agent was added to the PO composition and foaming was carried out in the same manner using a tandem extruder. In Comparative Examples 1 to 5, PTFE (B) was not used, and only the decomposition medium powder (C) was stirred with a Henschel mixer and kneaded with the polyolefin (A). In addition, Comparative Examples 6 and 7 show P even after mixing under high shear.
TFE (B) remained in the form of powder and did not form into fibers. Therefore, the rotation speed of the single screw extruder was changed from 50 rpm to 100 rpm.

The abbreviations in the table have the following meanings.

W501: Sumitomo Chemical Co., Ltd., Sumitomo Noblen W501, MI = 6 D501: Sumitomo Chemical Co., Ltd., Sumitomo Noblen D
501, MI = 0.5 H501: Sumitomo Chemical Co., Ltd., Sumitomo Noblen H
501, MI = 3 Z101A: Sumitomo Chemical Co., Ltd., Sumitomo Noblen Z
101A, MI = 20 F104: manufactured by Daikin Industries, Ltd., polyflon TFE
-F104, fine powder F201: manufactured by Daikin Industries, Ltd., Polyflon TFE
-F201, fine powder 7-J: DuPont, 7-J, molding powder 914-J: DuPont, TE-914-J, molding powder 10F-J: DuPont, TLP-10F-1, solid Lubricating powder use Core-shell body (I): Rubber-based core-shell graft copolymer, manufactured by Kanegafuchi Chemical Industry Co., Ltd., Kaneace FM20 core-shell body (II): Rubber-based core-shell graft copolymer, manufactured by Kanegafuchi Chemical Industry Co., Ltd. Kane Ace M511 Frozen powder: Homopolypropylene frozen powder, MI = 0.5, average particle size 250 microns Melt tension of the obtained PO composition, crystallization temperature and expansion ratio of the obtained foam, closed cell ratio (Hereinafter, referred to as autonomy rate) was measured by the following method. The results are shown in Table 3.

(Melt Tension) Using a PO composition, a Cabilograph manufactured by Toyo Seiki Co., Ltd., a piston speed of 5 mm
/ Min, take-up speed 1m / min, temperature in the parlor 200
It was measured at ° C.

(Crystallization temperature) DS manufactured by Perkin Elmer
In C, the temperature of the crystallization peak when the temperature was lowered at 10 ° C./min after holding at 200 ° C. for 5 minutes was determined as the crystallization temperature.

(Expansion Ratio) The density was measured according to JIS K7222, and the result was 0.9 / foam density = expansion ratio.

(Self-determination rate) It was measured according to ASTM-D-2856 with a multi-pycnometer manufactured by Yuasa Ionics Co., Ltd.

Example 11 Polytetrafluoroethylene (Polyflon TFE-F1)
04, fine powder) and 100 parts of homopolypropylene (Sumitomo Noblen W501 MI = 6) pellets 100 parts by a twin screw extruder with a screw diameter of 44 mm at 180 ° C, 100 rpm (two kneader parts)
Was extruded and kneaded to form polytetrafluoroethylene into fibers and pelletized to obtain a PO composition. Using these pellets, a board-like foam was obtained in the same manner as in Example 1. The obtained PO composition and foam were evaluated in the same manner as in Example 1, and the results are shown in Table 3.

As shown in Table 3, in Comparative Examples 1 to 5 in which PTFE (B) was not added, no foaming occurred. Further, even if PTFE (B) that did not become fibrous was added, the effect was not recognized as in Comparative Examples 6 and 7. On the other hand, Examples containing a specific amount of the crystalline polyolefin (A) and the fiberized PTFE (B) have effects of increasing melt tension and promoting crystallization,
A foam having a high expansion ratio and a high autonomy rate was obtained.

[0079]

[Table 1]

[0080]

[Table 2]

[0081]

[Table 3]

[0082]

INDUSTRIAL APPLICABILITY The foam of the present invention contains a specific amount of the crystalline polyolefin (A) and PTFE (B) fibrous substances, whereby the melt tension is increased and crystallization is promoted. Therefore, it is possible to easily obtain a foamed product having a preferable expansion ratio and a high autonomy rate.

Further, by further containing the nucleating agent (D), it is possible to impart further foamability and / or control the cell size.

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Claims (11)

[Claims] 1. A crystalline polyolefin foam containing 100 parts by weight of the crystalline polyolefin (A) and 0.001 to 10 parts by weight of a fibrous material of polytetrafluoroethylene (B). 2. The polytetrafluoroethylene (B) is
The crystalline polyolefin foam according to claim 1, which is a fine powder produced by aggregating an emulsion dispersion of polytetrafluoroethylene obtained by an emulsion polymerization method. 3. Polytetrafluoroethylene (B) and 5
A dispersion medium powder (C) having an average particle diameter of 0 to 700 microns is previously mixed under high shear to form polytetrafluoroethylene (B) into fibers, and then mixed with a crystalline polyolefin (A). The crystalline polyolefin foam according to claim 1 or 2. 4. The crystalline polyolefin foam according to claim 3, wherein the dispersion medium powder (C) is a polyolefin powder. 5. The crystalline polyolefin foam according to claim 3, wherein the dispersion medium powder (C) is a core-shell graft copolymer. 6. The crystalline polyolefin (A) is at least one selected from the group consisting of homopolypropylene, ethylene propylene random copolymer and ethylene propylene block copolymer.
Alternatively, the crystalline polyolefin foam according to item 5. 7. The crystalline polyolefin foam according to claim 1, wherein the melt flow index of the crystalline polyolefin (A) is 0.3 to 10 g / 10 minutes. 8. The crystalline polyolefin foam of claim 1, 2, 3, 4, 5, 6 or 7 processed by extrusion foam molding. 9. The crystalline polyolefin foam of claim 1, 2, 3, 4, 5, 6 or 7 processed by bead foam molding. 10. The composition according to claim 1, further comprising 0.001 to 2 parts by weight of the nucleating agent (D) with respect to 100 parts by weight of the crystalline polyolefin (A).
The crystalline polyolefin foam according to 5, 6, 7, 8 or 9. 11. The crystalline polyolefin foam comprises:
The crystalline polyolefin foam according to claim 10, which is a crystalline polyolefin foam sheet for thermoforming.