JPH05186611A - Anisotropic molded product and its production - Google Patents

Abstract

PURPOSE:To provide an isotropic molded product having a significant difference between the elastic modulus in the flow direction and that in the direction rectangular to the flow direction. CONSTITUTION:The objective molded product composed of (A) 50-99wt.% of (1) a block copolymer made up of vinyl aromatic compound-predominant polymer blocks and conjugated diene compound-predominant polymer blocks and/or (2) a hydrogenated product of the block copolymer and (B) 50-1wt.% of an aromatic vinyl polymer. For the molded product, the ratio of the elastic modulus in the flow direction (MMD) to that in the direction rectangular to the flow direction (MTD):MMD/MTD is >=1.5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is an anisotropic material in which there is a significant difference in the elastic modulus in the flow direction of a molded article and the elastic modulus in the direction perpendicular to the flow direction, and also in the strength and elongation. Molded article and its manufacturing method.

[0002]

2. Description of the Related Art Conventionally, anisotropic molded products, particularly anisotropic molded products such as sheets and films obtained by extrusion molding, have been obtained by uniaxially stretching using raw materials such as polyethylene and polypropylene. It is used as a flat yarn or binding tape for packaging materials and binding materials.

Such a conventional anisotropic molded article is obtained by reheating a sheet or film made of polyethylene, polypropylene or the like to a temperature not lower than the second-order transition temperature and not higher than the melting point, and stretching it with a roll several times. Thus, the molecules are oriented in the flow direction, and the strength in the flow direction is remarkably improved.

However, the sheet or film obtained by the above method is remarkably improved in the strength in the flow direction and is extremely useful as a binding tape for flat yarns, etc., but in the direction perpendicular to the flow direction. Both elastic modulus is extremely high, while strength and elongation are low.

Certain types of binding tapes, daily necessities, food packaging materials, sanitary goods, industrial parts, etc. require binding force, wrapping force and rigidity in one direction, and protect the products inside in the right direction. , To prevent damage due to binding,
Need to grow well.

As described above, there is a demand for a material having a high elasticity in the flow direction and a high strength and a low elastic modulus in the direction perpendicular to the flow direction and a good elongation, but such a material has not been obtained yet.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and there is a significant difference between the elastic modulus in the flow direction of a molded product and the elastic modulus in the direction perpendicular to the flow direction. The object is to provide an anisotropic molded article.

[0008]

DISCLOSURE OF THE INVENTION The present invention provides (a) a block copolymer comprising a vinyl aromatic compound-based polymer block and a conjugated diene compound-based polymer block and / or the block. copolymer and hydrogenated product 50 to 99 weight percent, and (b) an aromatic vinyl-based polymer from 1:50 molded article comprising by weight%, the elastic modulus of the flow direction of the molded article (M _MD) The present invention provides an anisotropic molded product having a ratio of elastic modulus (M _TD ) in the direction perpendicular to the flow direction of M _MD / M _TD ≧ 1.5, and a method for producing the same.

The component (a) of the present invention is a block copolymer (a-1) comprising a polymer block mainly composed of a vinyl aromatic compound and a polymer block mainly composed of a conjugated diene compound and / or It is a hydrogenated product (a-2) of a block copolymer. Block copolymer (a-1)
Is preferably 5 to 60% by weight of a vinyl aromatic compound,
More preferably 10 to 50% by weight, particularly preferably 1
0 to 45% by weight, the structure is linear,
It may be branched or radial, and is not particularly limited.

The block copolymer (a-1) is specifically represented by the general formula (Formula 1):

[Chemical 1] (In the formula, A is a polymer block mainly containing a vinyl aromatic compound, B is a polymer block mainly containing a conjugated diene compound, X is a coupling agent residue, and n is an integer of 1 or more.). Represented.

In the above general formula, the polymer block containing a vinyl aromatic compound as a main component means that the vinyl aromatic compound block is a vinyl aromatic compound alone or 60% by weight or more, preferably 80% by weight of a vinyl aromatic compound. It has a copolymer block structure of the vinyl aromatic compound and the conjugated diene compound contained above.

The polymer block containing a conjugated diene compound as the main component means that the conjugated diene compound block contains the conjugated diene compound alone or the conjugated diene compound contains 60% by weight, preferably 80% by weight, of the conjugated diene compound and vinyl aroma. The block may be a copolymer block with a group compound, in which vinyl aromatic compounds are randomly bonded, or a structure having one or more so-called tapered blocks gradually increasing.

Examples of the vinyl aromatic compound include styrene, α-methylstyrene, p-methylstyrene, vinylxylene, monochlorostyrene, dichlorostyrene, monobromostyrene, dibromostyrene, fluorostyrene and p-tertiarybutylstyrene. , Ethyl styrene, vinyl naphthalene, etc., which may be used alone or in combination of two or more. Of these, styrene is particularly preferable.

As the conjugated diene compound, 1,3-
Butadiene, 2-methyl-1,3-butadiene, 2,3
-Dimethyl-1,3-butadiene, 2-neopentyl-
1,3-Butadiene, 2-chloro-1,3-butadiene, 2-cyano-1,3-butadiene, substituted linear conjugated pentadienes, linear and side chain conjugated hexadienes and the like. Of these, particularly preferred are 1,3
-Butadiene, 2-methyl-1,3-butadiene.

The weight average molecular weight of the entire block copolymer (a-1) is preferably 10,000 to 500,000.
It is 0, more preferably 20,000 to 300,000. The block copolymer (a-1) is not only one type,
A combination of different structures and different vinyl aromatic compound contents may be used.

In addition to the above, the block copolymer (a-
Examples of 1) include block copolymers represented by the following general formulas (1) to (10). Formula (1) ~ (12): (1) A-B-C (2) A-B 1 -B 2 ( vinyl bond B ₁ represents preferably 20% or more, a vinyl bond of B ₂ is preferably 20 (Less than%) (3) A / B, (4) A-A / B, (5) A-A / B-C, (6) A-A / B-A, (7) C-B, (8 ) C-B-C, (9) C-A / B-C, (10) C-A-B (In the above general formulas (1) to (10), A is a vinyl aromatic compound and B is a conjugated diene. Represents a compound, A / B is a random copolymer of a vinyl aromatic compound and a conjugated diene compound, C is a copolymer of a vinyl aromatic compound and a conjugated diene compound, and a taper block in which the vinyl aromatic compound gradually increases Further, the hydrogenated product (a-1) of the block copolymer includes the above general formulas (1) to (1).
Also included are copolymers having a block skeleton represented by 0) as a basic skeleton and the like. Further, it may be a diene polymer obtained by coupling them.

AB ₁ -represented by the above general formula (2)
For the structure of B ₂ , see JP-A-2-133406.
Japanese Patent Laid-Open No. 63-127400 discloses the A / B structure represented by the general formula (3). In addition, A represented by the above general formula (4)
-A / B and A-A / B- represented by the general formula (5)
The structure of C is disclosed in JP-A-2-305814.

In the present invention, the block copolymer (a-
2) is obtained by hydrogenating the block copolymer (a-1). The weight ratio of the vinyl aromatic compound / conjugated diene compound in the hydrogenated product (a-2) of these block copolymers is 5 to 60/95 to 40, particularly 5 to 50.
/ 95 to 50, and more preferably 10 to 50/90 to 50. When the content of the vinyl aromatic compound exceeds 60% by weight, the vinyl aromatic compound becomes a resin and the flexibility of the obtained composition decreases. Further, the vinyl bond content of the conjugated diene portion of the block copolymer is preferably 10% by weight or more,
More preferably 20 to 90% by weight, particularly preferably 3
0 to 90% by weight. If it is less than 10% by weight, the structure after hydrogenation will be close to that of polyethylene, and the flexibility will decrease when it is made into a composition. If it exceeds 90% by weight, rubber after hydrogenation will be obtained. Since it loses its physical properties, it also becomes less flexible. Examples of the vinyl aromatic compound and the conjugated diene compound are the same as those used for the block copolymer (a-1).

Hydrogenation is preferably performed by 70% or more, more preferably 90% or more, of the double bond of the conjugated diene moiety.
It is particularly preferably carried out by adding 95% or more of hydrogen. The number average molecular weight of this hydrogenated product is preferably 5,000 to 1,000,000, more preferably 30,000 to 300,000. If it is less than 5,000, the hydrogenated product does not become a rubber-like liquid. And 1,
If it exceeds, 000,000, the workability tends to decrease. Further, the ratio (M _W / M _n ) of the weight average molecular weight to the number average molecular weight of the hydrogenated product is preferably 10 or less.

The block copolymer (a-1) and the hydrogenated product of the block copolymer (a-2) may be used alone or in combination of two or more different kinds. Good. Further, one or more block copolymers (a
-1) and the hydrogenated product (a-2) of the block copolymer may be used in combination.

Next, as the aromatic vinyl polymer (b), a homopolymer of a vinyl aromatic compound, a copolymer of this with another monomer, and a vinyl aromatic compound in the presence of a rubbery polymer are used. A block copolymer (a-1), which is a vinyl aromatic compound-based polymer modified with a rubbery polymer obtained by polymerizing an aromatic group compound or a vinyl aromatic compound with another monomer.
And block copolymers excluding the hydrogenated product (a-2), and these may be used alone or in combination.

Examples of the vinyl aromatic compound used in the aromatic vinyl polymer (b) include the vinyl aromatic compound used in the block copolymer (a-1). Other monomers copolymerizable with these vinyl aromatic compounds include vinyl cyanide compounds such as acrylonitrile and methacrylonitrile, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, amyl acrylate, hexyl acrylate. Acrylic acid esters such as octyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, dodecyl acrylate, octadecyl acrylate, phenyl acrylate and benzyl acrylate; methyl methacrylate, ethyl methacrylate,
Propyl methacrylate, butyl methacrylate, amyl methacrylate, hexyl methacrylate, octyl methacrylate, 2-ethylhexyl methacrylate,
Methacrylic acid esters such as cyclohexyl methacrylate, dodecyl methacrylate, octadecyl methacrylate, phenyl methacrylate and benzyl methacrylate; unsaturated acid anhydrides such as maleic anhydride, itaconic anhydride and citraconic anhydride; unsaturated acids such as acrylic acid and methacrylic acid; Maleimide, N-methylmaleimide,
N-butylmaleimide, N- (p-methylphenyl) maleimide, N-phenylmaleimide, N-cyclohexylmaleimide and other α- or β-unsaturated dicarboxylic acid imide compounds; glycidyl methacrylate and other epoxy compounds; acrylamide, methacrylamide And unsaturated carboxylic acid amides. These other copolymerizable monomers may be used alone or in combination of two or more.

The content of the vinyl aromatic compound in the aromatic vinyl polymer (b) is preferably 30% by weight or more, more preferably 50% by weight or more.

Specific examples of the aromatic vinyl polymer (b) include polystyrene, poly-o-methylstyrene and polym.
-Methylstyrene, poly-p-methylstyrene, styrene- (meth) acrylic acid copolymer, polychlorostyrene,
Poly α-methyl styrene, styrene-acrylonitrile copolymer, styrene-methyl methacrylate copolymer, styrene-maleic anhydride copolymer, styrene-α-methyl styrene copolymer, styrene-α-methyl styrene-
In addition to methyl (meth) acrylate copolymer, styrene-α-methylstyrene-acrylonitrile-methyl (meth) acrylate copolymer, for example, high-impact polystyrene, acrylonitrile-butadiene-styrene resin, acrylonitrile-ethylenepropylene-styrene Examples thereof include rubber modified products such as resins, methyl methacrylate-butadiene-styrene resins, and graft resin of methyl methacrylate with the hydrogenated product (a-2) of the block copolymer. These may be used alone or Used in combination of two or more.

The weight average molecular weight of the aromatic vinyl polymer (b) is preferably 5,000 to 1,000,000,
It is more preferably 10,000 to 700,000, and particularly preferably 20,000 to 500,000. 5,
If it is less than 000, the mechanical strength is poor, and
If it exceeds, the workability is remarkably poor.

A block copolymer (a-1) comprising a polymer block mainly composed of a vinyl aromatic compound and a polymer block mainly composed of a conjugated diene compound, and / or a hydrogenated product (a of the block copolymer (a -2) and the blending ratio of the aromatic vinyl polymer (b) are 50 to 99% by weight.
/ 50 to 1% by weight, preferably 55 to 95% by weight / 45
-5% by weight, more preferably 60-90% by weight / 40
10 to 10% by weight. When the aromatic vinyl polymer is 50% by weight or more, the elastic modulus in the direction perpendicular to the flow direction is high, and when it is 1% by weight, the elastic modulus in the flow direction becomes too low.
The anisotropic molded article aimed at by the present invention cannot be obtained.

In the present invention, the block copolymer (a
-1) and / or the blend of the hydrogenated product (a-2) of the block copolymer and the aromatic vinyl-based polymer (b), before molding, if necessary, by a conventionally known method, Modification such as maleation, carboxylation, hydroxylation, epoxidation, halogenation and sulfonation, or crosslinking such as sulfur crosslinking, peroxide crosslinking, metal ion crosslinking, electron beam crosslinking and silane crosslinking can be performed.

Further, additives used for usual thermoplastic resins can be added to the above-mentioned compound as required. For example, plasticizers such as phthalates, silica,
Fillers or reinforcing agents such as talc and glass fiber, other antioxidants, ultraviolet absorbers, antistatic agents, flame retardants,
A lubricant, a foaming agent, a colorant, a pigment, a core material, a cross-linking agent, a cross-linking aid, etc., or a mixture thereof can be added.

Other rubber-like polymers such as SBR, NBR, BR, EPT, EPR, NR, IR, etc.
1,2-polybutadiene, AR, CR, IIR, HSR
Etc. can also be added. In addition, if necessary, a thermoplastic resin such as a polyethylene resin, a polypropylene resin, a diene resin, a polyvinyl chloride resin,
A polyvinyl acetate resin, a polycarbonate resin, a polyacetal resin, a polyamide resin, a polyester resin, a polyether resin, polysulfone, polyphenylene sulphite, etc. can also be blended.

In the present invention, the compound thus obtained is molded under a predetermined molding condition so as to have a predetermined thickness, whereby the elastic modulus (M) in the flow direction of the molded product is obtained.
_MD) and flow perpendicular direction of the elastic modulus with respect to the direction (the ratio of _{M TD) (M MD / M} TD), 1.5 or more, preferably 2 to 30 or more, more preferably 3 to 20 or more. If the elastic modulus ratio (M _MD / M _TD ) of the obtained molded product is less than 1.5, the anisotropic molded product aimed at by the present invention cannot be obtained.

In the present invention, the elastic modulus means a modulus value at 100% elongation when a molded product is subjected to a tensile test.

The above-mentioned molding method itself is not particularly limited, and it can be carried out by a conventionally known method, for example, a molding method such as extrusion molding, calendering, injection molding, blow molding or the like. A molding method such as extrusion molding or an inflation method and a calendering method is preferable.

The above molding conditions cannot be uniquely defined because they differ depending on the molding method and the thickness of the molded product, but the following conditions are preferable. When molding a molded product having a thickness of 0.01 mm to 20 mm by extrusion molding: It is preferable to form at a cylinder temperature and a die temperature of 150 to 250 ° C. and a take-up speed of 0.3 to 150 m / min. Thickness of 0.01mm-20mm by calendering
When molding a molded product of: Roll temperature 120 to 250 ° C
Therefore, the take-up speed is preferably 0.3 to 150 m / min.

In the present invention, after the above-mentioned molding, secondary processing such as vacuum molding or laminating can be performed. Furthermore, in order to obtain the molded product of the present invention, it may be kneaded with a extruder (single screw, twin screw), a roll, a Banbury mixer, a kneader, a Henschel mixer, etc. before molding.

As described above, the thickness of the molded product obtained in the present invention varies depending on the molding method and molding conditions.
Usually 0.01 mm to 20 mm, preferably 0.01 mm
It is 10 mm, more preferably 0.01 mm to 5 mm. If the thickness of the obtained molded product is less than 0.01 mm, it is difficult to be a practical product, and if it is more than 20 mm, the elastic modulus in the flow direction ( _MMD ) and the elastic modulus in the direction perpendicular to the flow direction ( _MTD ).
It is difficult to make a difference with.

The molded article of the present invention has a high elasticity in the flow direction,
Utilizing the features of high strength and low elastic modulus in the direction perpendicular to the flow direction, (1) Food packaging, daily sundries, industrial products / parts, automobile parts, electrical products / products, etc. Film, (2) Agricultural film such as mulch film, fruit protection film, etc. (3) Paper diaper, sanitary back sheet, elastic tape film,
(4) Bundling tape for various packing, (5) Rubber products,
Cloths, non-woven fabrics and laminating films, (6) various hoses, tubes, (7) conveyor belts for foods, industrial parts, etc. (8) Other uses such as daily necessities, leisure goods, toys, industrial parts, etc. You can

[0037]

EXAMPLES The present invention will now be described in detail with reference to examples, but the present invention is not limited to these examples as long as the gist of the present invention is not exceeded. In the examples, parts and% are based on weight unless otherwise specified. In addition, in the examples, various physical properties were evaluated by the following methods.

Tensile Properties Molded products such as sheets and films obtained by the molding method described below were punched out with JIS No. 1 dumbbells, and a tensile speed of 500 mm with an Autograph IS5000 manufactured by Shimadzu Corporation.
/ Min was measured. Units of measured values are elastic modulus (elastic modulus is 100% elastic modulus, hereinafter simply referred to as modulus), tensile strength is g (gram), and elongation is%. MD represents the flow direction and TD represents the direction perpendicular to the flow direction. M _MD represents 100% modulus in the flow direction, and M _TD is 1 in the direction perpendicular to the flow direction.
Represents a 00% modulus.

The polymers used in the examples and comparative examples are as follows. GPPS: Polystyrene GPPS-1: Topolex 525 (manufactured by Mitsui Toatsu Chemicals) GPPS-2: Topolex 555 (〃
) HIPS: High-impact polystyrene Topolex HI830 (manufactured by Mitsui Toatsu Chemicals) AS: Acrylonitrile-styrene copolymer JSR AS230 (manufactured by Nippon Synthetic Rubber) MS: MMA-styrene copolymer Sebian MAS10 (manufactured by Daicel Chemical Industries) SMAH: Styrene-maleic anhydride copolymer Moamax UG830 (manufactured by Idemitsu Petrochemical) ABS: Acrylonitrile-butadiene-styrene copolymer JSR ABS12 (manufactured by Japan Synthetic Rubber) PP: Polypropylene PP-1: Mitsubishi Polypro MA-3 (Mitsubishi Oil) PP-2: 〃 BC-3 (〃) PE: Polyethylene Yucaron YK-30 (〃) SBS: Styrene-butadiene block copolymer SBS-1: JSR TR2825 (Nippon Synthetic Rubber) SBS-2: JSR T 2000 (〃) SIS: styrene - iso Bren block copolymer JSR SIS5000 (manufactured by Japan Synthetic Rubber) SEBS: Styrene - Ethylene - butylene block copolymer Kraton G1657 (manufactured by Shell Chemical)

Hydrogenated rubbers-1, -2 and hydrogenated block copolymers (hydrogenated rubber-1, -2,) were manufactured by Japan Synthetic Rubber Co., Ltd., and the following were used. Hydrogenated rubber-1: having an AB structure (A is a polystyrene block, B is a copolymer of styrene and butadiene having hydrogenated double bonds in the butadiene part of the copolymer block), and the total bound styrene is 10%, A hydrogenated block copolymer having a styrene content of 6% in the A part, a vinyl content (1,2 bond content) of the butadiene part before hydrogenation of 80%, and a total molecular weight of 300,000. Hydrogenated rubber-2: A-C-D structure (A is a polystyrene block, C and D are polybutadiene block hydrogenated products)
With 20% of total bound styrene and 2 parts of styrene
0%, the amount of vinyl in parts C and D before hydrogenation is 50%,
Hydrogenated block copolymer having a total molecular weight of 200,000, which is 8%.

Examples 1-12, Comparative Examples 1-9 50 mmφ with a 400 mm wide T-die attached to the tip
The composition shown in Table 1 was extruded with an extruder (manufactured by Nippon Placon) under the following conditions, and then a molded product was obtained with a 500 mm width take-off machine. Extruder cylinder temperature 180-230 ℃,
The temperature of the T-die is 170 to 230 ° C, the roll temperature of the take-up machine is 15 to 50 ° C, and the take-up speed is 2 m / min-
It was performed at 20 mm / min.

[0042]

[Table 1] Table 1 shows the performance of the molded articles of Examples 1 to 12 made of polystyrene, high-impact polystyrene and block copolymer. The molded articles of Examples 1 to 12 are 10
At 0% modulus, the ratio of the elastic modulus in the flow direction to the elastic modulus in the direction perpendicular to the flow direction (M _MD / M _TD ) is large, and it can be seen that the anisotropic molded article aimed at by the present invention is obtained. ..

[0043]

[Table 2] Table 2 shows the performance of the molded articles (Comparative Examples 1 to 9) when compositions other than the scope of the present invention or when polypropylene or polyethylene was used in place of polystyrene were used. It can be seen that a molded product cannot be obtained.

Examples 13 to 16 and Comparative Examples 10 and 11 In Table 3, molded articles were prepared in the same manner as in Examples 1 to 12 except that a copolymer of polystyrene and another monomer was used instead of polystyrene. When obtained, Examples 13 to 16 and Comparative Example 1
Indicates 0 and 11. In addition, the conditions of extrusion molding are Examples 1 to 1.
The same as 2.

[0045]

[Table 3] From Table 3, it can be seen that the anisotropic molded article aimed at by the present invention can be obtained by using other monomer contained in the component (b) of the present invention instead of polystyrene. Further, it can be seen that if the component (a) of the present invention is less than 50% and the component (b) is more than 50%, the anisotropic molded product of the present invention cannot be obtained.

Examples 17 to 20 and Comparative Examples 12 and 13 In the case where molded products are obtained in the same manner as in Examples 1 to 12 except that the block copolymer is used in combination as the component (b) of the present invention in Table 4. 17 to 20 and Comparative Examples 12 and 13 are shown. The conditions for extrusion molding are the same as in Examples 1-12.

[0047]

[Table 4] It can be seen from Table 4 that the anisotropic molded article aimed at by the present invention can be obtained even when the block copolymer is used in combination. Further, it is understood that when the ratio of the component (a) to the component (b) of the present invention is outside the range of the present invention, an anisotropic molded product cannot be obtained even if the block copolymer is used in combination.

Examples 21, 22 and Comparative Examples 14, 15 In Table 5, the molded articles were obtained in the same manner as in Examples 1-12 except that the thickness of the molded article was changed. The physical properties of 14 and 15 are shown. The conditions for extrusion molding are the same as in Examples 1-12.

[0049]

[Table 5] In Examples 21 and 22, the thickness of the molded product was changed, and the anisotropic molded products intended by the present invention were obtained.
Further, Comparative Examples 14 and 15 are the components (a) of the present invention and (b).
The ratio of the components is outside the range of the present invention, and the anisotropic molded article aimed at by the present invention cannot be obtained.

[0050]

EFFECTS OF THE INVENTION The anisotropic molded article of the present invention has a significant difference between the elastic modulus in the flow direction and the elastic modulus in the direction perpendicular to the flow direction.
It is industrially valuable because it can be suitably used for sanitary items such as paper diapers and sanitary items, and also for industrial parts. Further, according to the method for manufacturing an anisotropic molded product of the present invention, an anisotropic molded product can be manufactured without performing a complicated drawing operation, so that the manufacturing cost can be reduced.

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Claims (2)

[Claims] 1. A block copolymer comprising (a) a polymer block mainly composed of a vinyl aromatic compound and a polymer block mainly composed of a conjugated diene compound and / or a hydrogenated product 50 of the block copolymer. ~ 99% by weight,
(B) an aromatic vinyl-based polymer from 1:50 molded article comprising by weight%, the elastic modulus of the flow direction of the molded article (M _MD)
And an elastic modulus (M _TD ) ratio in the direction perpendicular to the flow direction is M _MD / M _TD ≧ 1.5, an anisotropic molded article. 2. A block copolymer comprising (a) a polymer block mainly containing a vinyl aromatic compound and a polymer block mainly containing a conjugated diene compound, and / or a hydrogenated product 50 of the block copolymer. ~ 99% by weight,
(B) A molded article obtained by extrusion molding or calendering a mixture comprising 50 to 1% by weight of an aromatic vinyl polymer so as to have a thickness of 0.01 mm to 20 mm. Elastic modulus in the product flow direction ( _MMD )
And an elastic modulus (M _TD ) ratio in the direction perpendicular to the flow direction is M _MD / M _TD ≧ 1.5, an anisotropic molded article.