JP3362080B2 - Polypropylene resin composition and flexible sheet - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polypropylene resin having excellent workability and secondary workability as a material for automobile interiors, and in particular, vacuum forming, pressure forming, etc. after embossing and embossing. Thus, a polypropylene resin composition excellent in moldability in which a grain pattern does not disappear and easily decorated is provided, and a soft sheet produced using the same.

[0002]

2. Description of the Related Art Automotive interior materials such as door skins, instrument panels, armrests, grips, ceilings, etc. are made of a material obtained by subjecting a sheet, the surface of which is embossed to a texture, to a secondary processing such as vacuum forming. Such a member is generally manufactured by the following method. (1) A sheet is manufactured by calendering or extruding a raw material resin. (2) The sheet is embossed and embossed to decorate. (3) The textured sheet is formed into a predetermined shape by vacuum forming or the like to obtain a member. As a material suitable for such a production method, a thermoplastic elastomer composition comprising a blend of a polyolefin resin and a partially crosslinked α-olefin copolymer rubber is known, and the elastomer composition is prepared according to the above method. It can be easily used as an automobile interior member. However, in the production thereof, it is necessary to appropriately control the degree of crosslinking of the partially crosslinked α-olefin copolymer rubber used in the thermoplastic elastomer composition, and if the degree of crosslinking is unsuitable, sheet molding, embossing, It has the drawback that each process such as vacuum forming becomes difficult.

On the other hand, when a blended product of an α-olefin copolymer rubber that is not cross-linked with a polyolefin resin is used as an automobile interior material, the embossing gives a texture that has been embossed in advance. However, it is difficult to decorate, there is a large drawdown during vacuum forming, and as a result it is difficult to obtain a uniform thickness when deep drawing in vacuum forming. Development of a soft resin composition suitable for secondary processing such as molding is desired.

[0004]

SUMMARY OF THE INVENTION The present invention is suitable for the above-mentioned manufacturing method, is easy to manufacture because it is inexpensive and does not require troublesome control of the degree of cross-linking like a thermoplastic elastomer, and prevents the flow of grain. An object of the present invention is to develop a resin composition having a small drawdown and capable of obtaining a uniform product thickness even during deep drawing in vacuum forming.

[0005]

Means for Solving the Problems The present inventor uses a resin composition containing a polypropylene resin having a specific property to prevent the α-olefin copolymer rubber from cross-linking, which is the above-mentioned problem. Prevention of drawdown,
It has been found that the problem of the uniform thickness of the product can be solved, and the polypropylene resin composition of the present invention and the soft sheet which can be obtained from it and which is easy to decorate such as moldability and embossing have been completed. That is, in the present invention, (a) the branching index is less than 1.0, and has strain hardening elongational viscosity,
A composition comprising a polyolefin-based resin containing polypropylene having no gel component, and (b) an α-olefin copolymer rubber, wherein the total amount of the components (a) and (b) is 100 parts by weight. The polypropylene resin composition characterized in that the component (a) is in the range of 15 to 85 parts by weight, and the polypropylene resin composition is formed into a sheet by calendar molding or extrusion molding, and then the surface of the sheet is embossed. The above problems have been solved by developing a soft sheet characterized by being attached.

In the present invention, a gel-free polypropylene (hereinafter referred to as branched polypropylene) characterized by having a branching index of less than 1 and having a strain hardening elongational viscosity will be described below. The branching index g is to quantify the degree of long-chain branching, and the branched polypropylene used in the present invention is 1.0.
It is less than 0.8, preferably less than 0.8, and more preferably 0.2 to 0.4. The branching index g is defined by the following formula. g = [η] _sr / [η] _Lin [where [η] _sr is the intrinsic viscosity of branched polypropylene, and [η] _Lin is the intrinsic viscosity of linear polypropylene having substantially the same weight average molecular weight. In this case, the length of the branched long chain is unknown, but by having the long chain branching, [η] _sr becomes small, and thus the branching index g becomes small. Therefore, by introducing long chain branching, the branching index g can be made 1 or less, and generally, the smaller the branching index g is, the more long chain branching is. The intrinsic viscosity of polypropylene is measured by Elliott (E
Lliott) et al. App. polym. Sc
i. , Vol. 14, pp. 2947-2963, (1970). In the present invention, the intrinsic viscosity in each case is measured at 135 ° C. for a sample dissolved in decahydronaphthalene.

Elongation viscosity is the resistance of a fluid or semi-fluid material to elongation. That is, "indicates strain-hardening elongational viscosity." Means that in the measurement of elongational viscosity, "a phenomenon in which the elongational viscosity increases as the amount of elongation increases" is shown, and in ordinary modified polypropylene or ordinary polypropylene, It does not show "strain hardening elongational viscosity" and the elongational amount of elongational viscosity is very small. Having the strain-hardening elongational viscosity of the present invention refers to those having this property. Then, by introducing a long chain branch, strain-hardening elongational viscosity is exhibited, and this property is one factor that facilitates obtaining a uniform wall thickness in vacuum forming. This elongational viscosity can be measured by an apparatus for measuring stress and strain of a sample in a molten state when it is subjected to tensile strain at a constant rate. Such a device is Munstedt
J. Rheology, 23 (4), 421-425.
(1975). In general, the longer the long chain branching is, the more the elongation viscosity of the polypropylene increases with the elongation of the branch and the more it tends to brittle fracture or elastic fracture, that is, strain hardening. This tendency is most remarkable when the branching index g is less than 0.8. The composition of the present invention containing such a polypropylene having a strain hardening property and a branching index g of a value of less than 1.0 shows a good wrinkle resistance and a resistance to the flow of wrinkles during vacuum forming. Further, there is an advantage that a molded body having a uniform thickness can be obtained in vacuum molding.

If the branched polypropylene used in the present invention contains a gel, it becomes difficult to use it as an interior material for automobiles, such as a reduction in impact resistance and a deterioration in appearance. The branched polypropylene of the present invention can be produced by irradiating the polypropylene with radiation, and can be produced, for example, according to JP-A-62-121704. Further, without being limited to this, it is possible to manufacture using a known technique of introducing branching.

As another example of the method for producing a branched polypropylene of the present invention, a modified polypropylene (A) grafted with at least one unsaturated carboxylic acid and its derivative is reacted with this unsaturated carboxylic acid and its derivative. There is a method of reacting a compound (B) having at least two functional groups in the molecule and having a molecular weight of 3000 or less.

In this case, the raw material polypropylene used for the production of the modified polypropylene as the component (A) is a crystalline polypropylene resin such as propylene homopolymer, ethylene-propylene block copolymer, ethylene-propylene random copolymer and a mixture thereof. . The ethylene content of the ethylene-propylene block copolymer and the ethylene-propylene random copolymer is not particularly limited, but is usually 20% by weight or less. The MFR at 230 ° C. and a load of 2.16 kg is not particularly limited, but is usually 0.01 kg / 10 minutes to 100 g / 1.
It is in the range of 0 minutes. Also, those obtained by copolymerizing a small amount of dienes such as 1,9-decadiene, 1,5-hexadiene, 1,4-hexadiene, isoprene, 1,3-butadiene, 1,3-pentadiene at the time of polymerization of these. Can be used.

Examples of the unsaturated carboxylic acid and / or its derivative (hereinafter referred to as unsaturated carboxylic acid compound) for obtaining the modified polypropylene as the component (A) include acrylic acid, methacrylic acid, maleic acid, fumaric acid and itaconic acid. , Citraconic acid, crotonic acid, isocrotonic acid, maleic anhydride, itaconic anhydride, endic anhydride,
Examples thereof include citraconic anhydride, 1-butene-3,4-dicarboxylic acid anhydride, and alkenyl succinic anhydride having a double bond at the end having 18 carbon atoms. These two types may be used at the same time. Of these, maleic anhydride and itaconic anhydride are preferably used.

The unit derived from the unsaturated carboxylic acid of the component (A) modified polypropylene is 0.001 to 10% by weight.
, Preferably in the range of 0.05 to 2.0% by weight, and more preferably in the range of 0.1 to 1.0% by weight. When the unit derived from unsaturated carboxylic acid is less than 0.001% by weight, the branching index of less than 1.0 is not satisfied. On the other hand, if it exceeds 10% by weight, gel is formed, resulting in a large loss of physical properties such as appearance and impact resistance. MFR of component (A) (JIS K-7210, Table 1, Condition 1)
4, temperature 230 ° C., load 2.16 kg) is not particularly limited, but is usually in the range of 0.01 to 1000 g / 10 minutes. In producing the component (A), a resin other than polypropylene, a rubber, a filler such as a filler, an additive such as an antioxidant and an ultraviolet absorber may be contained within a range not departing from the gist of the present invention.

The method for producing the component (A) is not particularly limited,
For example, polyolefins are dissolved in a solvent to form a solution, and a solution grafting method in which a radical initiator and an unsaturated carboxylic acid or a derivative thereof are mixed and reacted, a melt grafting method in which modification is performed in an extruder in the absence of a solvent, an electron beam A radiation grafting method utilizing the can be preferably used. At this time, after the production of the component (A), washing with a solvent, warm water or the like may be carried out for the purpose of removing the unsaturated carboxylic acid compound and by-products of the end reaction.

On the other hand, the functional group contained in the component (B) is one that reacts with the unsaturated carboxylic acid or its derivative in the component (A), and examples thereof include a hydroxyl group, an amino group, an epoxy group and an isocyanate group. Can be mentioned. Particularly preferred are a hydroxyl group, an amino group and an epoxy group. Ingredient (B)
Examples of the compound include the following.

As the polyhydric alcohol having two or more hydroxyl groups in the molecule, for example, glycols such as ethylene glycol, diethylene glycol and triethylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,8- Alcohol compounds such as octanediol, 1,10-decanediol, trimethylolethane, trimethylolpropane, pentaerythritol, dipentaerythritol, arbitol, sorbitol, xylose, arabinose, glucose, galactose,
Sugars such as sorbose, fructose, palatinose, maltotriose, and malezitose; saponification products of ethylene-vinyl acetate copolymers, polyvinyl alcohol, polyolefin oligomers having a plurality of hydroxyl groups, ethylene-hydroxyethyl (meth) acrylate copolymers, etc. Examples thereof include polymers having a plurality of hydroxyl groups in the molecule.
Further, a polyoxyalkylene compound having a structure in which ethylene oxide or propylene oxide is added to a polyhydric alcohol compound, and a polyglycerin ester obtained by dehydrating and condensing these with an organic carboxylic acid compound, and the like can be mentioned. These compounds may be used in combination of two or more kinds at the same time.

The above polyoxyalkylene compound includes
Compounds obtained by adding propylene oxide to trimethylolpropane, compounds obtained by adding ethylene oxide to trimethylolpropane, compounds obtained by adding ethylene oxide to pentaerythritol, compounds obtained by adding propylene oxide to diglycerin, compounds obtained by adding ethylene oxide to tetraglycerin. , A compound obtained by adding propylene oxide to decaglycerin, and a mixture thereof.

Specific examples of these polyoxyalkylene compounds include 1,3-dihydroxypropane, 2,2-dimethyl-1,3-dihydroxypropane, trimethylolethane and 1,1,1-tri Methylolpropane, 1,1,1-trimethylolhexane,
1,1,1-trimethylol dodecane, 2-cyclohexyl-2-methylol-1,3-dihydroxypropane, 2- (p-methylphenyl) -2-methylol-
Examples thereof include compounds in which 1,3-dihydroxypropane, pentaerythritol, glycerin, diglycerin, hexaglycerin, octaglycerin, decaglycerin and the like are subjected to an addition reaction with ethylene oxide or propylene oxide, and mixtures thereof.

Specific examples of the polyglycerin ester as described above include glycerin monostearate, glycerin monooleate, glycerin monolaurate, glycerin monocaprylate, glycerin monohexanoate and glycerin mono Phenethyl ester, glycerin monopropionate, diglycerin monostearate, diglycerin distearate, diglycerin monooleate, diglycerin monohexanoate, diglycerin dioctanoate, tetraglycerin monostearate, tetraglycerin tri Stearate, tetraglycerin tetrastearate, tetraglycerin trihexanoate, tetraglycerin monophenethyl ester, hexaglycerin monostearate,
Hexaglycerin distearate, hexaglycerin pentastearate, hexaglycerin trioleate,
Hexaglycerin monolaurate, hexaglycerin pentalaurate, decaglycerin monostearate, decaglycerin octastearate, decaglycerin pentaoleate, decaglycerin monolaurate, decaglycerin dilaurate, pentadecaglycerin distearate, pentadecaglycerin Examples include decaoleate, octadecaglycerin tetrastearate, and mixtures thereof.

Further, as the sorbitan alkyl ester, for example, sorbitan monostearate, sorbitan monooleate, sorbitan monolaurate, sorbitan monocaprylate, sorbitan monohexanoate, sorbitan monophenethyl ester, sorbitan monopropionate, sorbitan. Examples thereof include tristearate and sorbitan tetrastearate. Among these, preferred are those having a valence (number of hydroxyl groups in one molecule) of 3 to 7. These compounds may be used in combination of two or more kinds at the same time.

The compounds having a plurality of amino groups in the molecule include ethylenediamine, diaminopropane, diaminobutane, 1,2-dimethyl-1,3-propanamine,
Hexamethylenediamine, 2-methyl-1,5-pentadiamine, diaminoheptane, diaminooctane, 2,
5-dimethyl-2,5-hexanediamine, diaminononane, diaminodecane, diaminododecane, diethylenetriamine, N- (aminoethyl) -1,3-methyldipropanediamine, 3,3'-diamino-N-methyldipropylamine 3,3′-iminobispropylamine, triethylenetetramine, tris (2-aminoethyl) amine, tetraethylenepentamine, 1,4-diaminocyclohexane, polyethyleneimine and the like. These compounds may be used in combination of two or more kinds at the same time.

Alternatively, a compound having both an amino group and a hydroxyl group can be used. For example, ethanolamine 2-hydroxyethylhydrazine, 3-amino-1-propanol, DL-2-amino-1-propanol, DL-1
-Amino-2-propanol, 4-amino-1-butanol, 2-amino-1-butanol, 2-amino-1-
Pentanol, DL-2-amino-1-pentanol,
6-amino-1-hexanol, 2- (2-aminoethoxy) ethanol and the like are used. These compounds may be used in combination of two or more kinds at the same time.

Examples of the compound having a plurality of epoxy groups in the molecule include sorbitol polyglycidyl ether,
Polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, hydroquinone diglycidyl ether, diglycidyl bisphenol A and hydrogenated products thereof, phthalic acid diglycidyl ester, trimethylolpropane triglycidyl ether, butanediol diglycidyl ether, epoxidized soybean oil , Epoxidized linseed oil, cyclohexanedimethanol diglycidyl ether, hexanetriol glycidyl ether,
Alicyclic epoxy resin, heterocyclic epoxy resin, brominated epoxy resin, bisphenol A-epichlorohydrin resin, polyfunctional epoxy resin, aliphatic epoxy resin, brominated novolac type epoxy resin, brominated bisphenol A type Examples thereof include epoxy resin, biphenyl type epoxy resin, polyglycidyl amine type epoxy resin, ester type epoxy resin, orthocresol novolac type epoxy resin, phenol novolac type epoxy resin and the like. These compounds may be used in combination of two or more kinds at the same time.

Examples of the compound having a plurality of isocyanate groups in the molecule include ethylene diisocyanate, diisocyanate butane, diisocyanate hexane, diisocyanate dodecane, diisocyanate-2-methylpentane and m-phenylenediene. Isocyanate, p-phenylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,5-
Naphthylene diisocyanate, 4 ', 4', 4 "-triphenylmethane triisocyanate, 4,4 'diphenylmethane triisocyanate, 3,3'-dimethyl-
4,4′-diphenylene diisocyanate, m-xylylene-diisocyanate, p-xylylene-diisocyanate and the like can be mentioned. Two or more kinds of these compounds may be used in combination at the same time.

The molecular weight of these components (B) is particularly preferably 3,000 or less from the viewpoint of suppressing the formation of gel, but those having a molecular weight exceeding this can also be used. The melting point of these compounds is preferably 300 ° C. or lower.

The amount of the component (B) used is such that the molar ratio of the functional group in the component (B) is 0.1 to the acid anhydride unit derived from the unsaturated carboxylic acid or its derivative contained in the modified polyolefin. The range is 10. Preferably 0.14 to 7
The range is more preferably 0.2 to 5. If this ratio is less than 0.1, the branching index of branched polypropylene will not satisfy less than 1, and if it exceeds 10, gel will be formed.

In reacting the component (A) with the component (B), the reaction between the unsaturated carboxylic acid of the component (A) and its derivative with the hydroxyl group, amino group, epoxy group or isocyanate group of the component (B) is carried out. A reaction accelerator that accelerates can be used. As such a reaction accelerator, known compounds can be preferably used, and examples thereof include metal salts of organic carboxylic acids. Examples of metal salts of organic carboxylic acids include metal salts of fatty acids having 1 to 30 carbon atoms, such as acetic acid, butyric acid octanoic acid, decanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, behen. IA, IIA, IIB of the periodic table of carboxylic acids such as acids
Group IIIB group (eg Li, Na, K, Mg, Ca, Z
n, Al, etc.).

The content of branched polypropylene in the component (a) must be 10% by weight or more. The content of branched polypropylene in the polypropylene resin composition comprising the components (a) and (b) is preferably 3% by weight or more, more preferably 5% by weight or more.

The components other than the branched polypropylene will be described below. Examples of the polyolefin resin other than the branched polypropylene that may be used as the component (a) in the present invention include low density polyethylene, high density polyethylene, linear low density polyethylene, polypropylene, ethylene-propylene block copolymer, ethylene-propylene random copolymer. , Polybutene, etc. and mixtures thereof.

Of these polyolefin resins, crystalline polypropylene resins such as propylene homopolymers, ethylene-propylene block copolymers and ethylene-propylene random copolymers and mixtures thereof are preferred from the viewpoint of heat resistance. The ethylene content of the ethylene-propylene block copolymer and the ethylene-propylene random copolymer is not particularly limited, but is usually 20% by weight or less. The MFR at 230 ° C. and a load of 2.16 kg is not particularly limited, but is usually 0.01 g / 10.
The range is from minutes to 100 g / 10 minutes.

The α-olefin copolymer rubber that can be used in the present invention is at least 2 of the compounds having an ethylenically unsaturated bond having a carbon number of 2 to 12.
It is obtained by copolymerizing more than one species,
Examples thereof include ethylene-propylene copolymer rubber (hereinafter abbreviated as EPM), ethylene-butene copolymer rubber (hereinafter abbreviated as EBM), ethylene-propylene-diene copolymer rubber (hereinafter abbreviated as EPDM), and the like. These mixtures are mentioned. Among these, EPM, EPDM, or a mixture thereof is preferable because they are easily available and have good mechanical properties.

The propylene content in these EPMs and EPDMs is usually in the range of 10% by weight to 80% by weight, preferably 20% by weight to 75% by weight, more preferably 30% by weight to 60% by weight.

As the diene component in EPDM,
1,4-pentadiene, 1,4-hexadiene, cyclohexadiene, dicyclopentadiene, 5-ethylidene-2-norbornene and the like can be mentioned.

As the ethylene-α-olefin copolymer rubber, either an amorphous one obtained by a known method or a partially crystalline one can be used, and the thermoplastic resin composition is used. From the viewpoint of mechanical strength when used as a material, a material partially having crystallinity is desirable. Their crystallinity is determined by X-ray diffraction and is usually 0% or more 2
It is 5% or less, preferably 2% or more and 20% or less, and more preferably 5% or more and 15% or less.

The MFR of these ethylene-α-olefin copolymer rubbers (JIS K7210 at 230 ° C.,
2.16 kg load) is 0.001 to 100 g / 1
It is 0 minutes, preferably 0.005 to 10 g / 10 minutes, and more preferably 0.01 to 5 g / 10 minutes. MFR is 10
If it exceeds 0, the mechanical strength of the thermoplastic resin composition decreases, and if it is less than 0.001, the fluidity becomes poor.

Resins other than polyolefins, rubbers other than α-olefin copolymer rubbers, and the following softening agents, fillers, additives and the like can be added within the scope of the present invention.

Examples of the resin other than the polyolefin resin include polyamide, polyester, polycarbonate, acrylic resin and the like.

As the rubber other than the α-olefin copolymer rubber, natural rubber, polybutadiene, polyisoprene, styrene-butadiene copolymer rubber, styrene-isoprene copolymer rubber, chloroprene rubber, acrylonitrile-butadiene copolymer rubber, Acrylic rubber etc. are mentioned.

As the softening agent, commercially available process oil and the like can be preferably used. These are added for the purpose of promoting the plasticization of the rubber, improving the fluidity of the resulting thermoplastic resin composition, and the like. These may be paraffin-based, naphthene-based, or aromatic-based, but paraffin-based ones are particularly preferable because of good color tone and weather resistance. Examples of the filler include calcium carbonate, talc, silica, kaolin, clay, diatomaceous earth, calcium silicate, asbestos, mica, alumina, aluminum sulfate, barium sulfate, calcium sulfate, magnesium carbonate, carbon fiber, glass fiber, glass sphere, and sulfide. Examples thereof include molybdenum, graphite, shirasu balloon and the like.

The additives include a heat resistance stabilizer, a weather resistance stabilizer, a colorant, an antistatic agent, a flame retardant, a nucleating agent, a lubricant, a slip agent, an antiblocking agent and the like. As the heat resistance stabilizer, known compounds such as phenol type, phosphorus type and sulfur type can be used. Examples of the colorant include carbon black, titanium white, zinc white, red iron oxide, azo compounds, nitroso compounds, phthalocyanine compounds and the like. Known antistatic agents, flame retardants, nucleating agents, lubricants, slip agents, antiblocking agents and the like can be used.

The polypropylene resin composition of the present invention is 19
It is essential that the melt strength at 0 ° C. is 15 g or more, but if the melt strength is less than 15 g, the following problems occur. That is, the drawdown during vacuum forming is extremely difficult to form, and it is difficult to achieve the purpose of decoration by causing the embossed grain to flow. From this point of view, the preferable range of the melt strength is 20 g or more, more preferably 25 g or more.

The flexural modulus of the polypropylene resin composition of the present invention is 4,000 kg / cm ² or less, and if it exceeds this value, the flexibility required when used as a member for automobile interiors is impaired. From this point of view, the bending elastic modulus is preferably 2,500 kg / cm ² or less, and more preferably 1,500 kg / cm ² or less.

Component (a): a polyolefin resin containing branched polypropylene and component (b): an α-olefin copolymer rubber are mixed in proportions of (a) component and (b) component being 100 parts by weight in total. Component (a) is in the range of 15 to 85 parts by weight. If the amount of the component (a) is less than 15 parts by weight, drawdown during vacuum forming is remarkable, and the object of the present invention cannot be achieved. On the other hand, when it exceeds 85 parts by weight, it becomes difficult to satisfy the flexural modulus of 4,000 kg / cm ² or less. Further, in order to obtain a flexible composition while maintaining the advantages of easy decorating property and good vacuum forming property, the preferred range of the component (a) is 15 to 50 parts by weight,
It is more preferably 15 to 40 parts by weight.

The polypropylene resin composition of the present invention is prepared by preliminarily mixing the above-mentioned component (a), the α-olefin copolymer rubber and other compounding ingredients with a Henschel mixer or the like, and then using a usual twin-screw extruder or It is prepared by heating and kneading with a kneading machine such as a single-screw extruder or a Banbury mixer. The temperature at the time of kneading is preferably higher than or equal to the softening point of the resin used and is usually between 100 ° C and 300 ° C. Next, the soft sheet of the present invention is manufactured according to the following steps.

(1) A sheet is produced from a raw material polypropylene resin composition by a calender molding machine or an extrusion molding machine. (2) The sheet is embossed and embossed to decorate. In the step (1), there is no limitation on the calender molding and extrusion molding methods, and a normal calender molding machine or extrusion molding machine can be preferably used. The melted sheet introduced from the roll of the calender molding machine or the T-die of the extrusion molding machine may be used in the embossing step after being once cooled and molded into a sheet. It is also possible to use it directly in the embossing process without cooling.

The embossing is carried out by rolling the sheet in a molten state by means of an embossing roll, and as a result, a soft sheet with a textured and decorated surface is obtained. The sheet in the molten state may be formed by cooling the molten resin introduced from the T-die of the calender molding machine or the extrusion molding machine into a sheet once as described above, and heating the resin again to bring it into a molten state, It is also possible to use the molten sheet directly without cooling. The thus-decorated soft sheet thus obtained can be used not only for automobile interior materials such as door skins, instrument panels, armrests, grips and ceilings but also for stationery and sundries.

[0046]

The present invention requires a delicate adjustment of the degree of cross-linking in a thermoplastic elastomer composition used as an interior material for automobiles, and this incompatibility causes troubles. Partially cross-linked α-olefin copolymer rubber. Was investigated, and the development of a resin composition that can use inexpensively available α-olefin-based copolymer rubber was studied, and succeeded by combining it with a resin composition containing a polypropylene resin having certain specific properties. . That is, although it has not been confirmed,
By using a polyolefin resin containing polypropylene having a branching index of less than 1.0 and having strain hardening elongation viscosity and having no gel, long-chain branching contained in the polyolefin resin is α-olefin copolymerization. It is presumed that the effect that does not require partial crosslinking of the united rubber is achieved.

[0047]

The present invention will be described in detail below with reference to examples, but the present invention is not limited thereto. (Branched polypropylene-1) Branched polypropylene-1 was produced by irradiating an MFR (230 ° C, load 2.16 kg) 5.2 polypropylene (homopolymer) with an electron beam under a nitrogen stream. The characteristic values of the obtained branched polypropylene-1 were as follows. MFR (230 ° C, load 2.16kg) 12g / 10 branching index (decahydronaphthalene 135 ° C) 0.3

(Branched polypropylene-2) Maleic anhydride graft-modified polypropylene (MFR 20 g / 10 minutes, maleic anhydride-derived unit: 0.23% by weight) ... 100 parts by weight trimethylolpropane triglycidyl ether (Dainippon Ink Chemical industry Epicron 725, epoxy equivalent 141) (epoxy group / maleic anhydride = 1.0) ... 0.33 parts by weight The above components were melt-kneaded at 220 ° C with a 30 mmφ twin-screw extruder. The characteristic values of the obtained branched polypropylene-2 were as follows. MFR (230 ° C, load 2.16kg) 8.0g / 10 branching index (decahydronaphthalene 135 ° C) 0.4

[0049] (Propylene homopolymer)       MFR (230 ° C, load 2.16kg) 1.0g / 10min (Propylene random copolymer)       MFR (230 ° C, load 2.16kg) 0.8g / 10min       Ethylene content 7.0% by weight (EPM)       MFR (230 ° C, load 2.16kg) 1.0g / 10min       Propylene content 38% by weight (EPDM)       MFR (230 ° C, load 2.16kg) 0.7g / 10min       Propylene content 35% by weight       ENB content 5.0% by weight           * ENB: 5-ethylidene-2-norbornene

[Examples 1 to 8] (Preparation of thermoplastic resin composition) The above-mentioned branched polypropylene resin, polyolefin resin, α-olefin copolymer rubber and others were blended in the proportions shown in Table 1 and 2
A polypropylene resin composition was obtained by kneading at 200 ° C. using a shaft extruder. (Production of Soft Sheet) The polypropylene resin composition was formed into a molten sheet by an extruder equipped with a T-die or a calender molding machine, and then embossed at 60 ° C. to give a soft sheet to give a soft sheet. .

(Melt Tension) A melt tension tester type II manufactured by Toyo Seiki Co., Ltd. was used and measured under the following conditions. Orifice inner diameter 2.095 ± 0.005 mm,
Orifice length 8.000 ± 0.025 mm, resin temperature 230 ° C., take-up speed 6.5 m / min, extrusion speed 15 mm /
Minutes. (Resistance to wrinkle flow) The soft sheet obtained above was heated at a predetermined temperature and the change in gloss before and after the heating was measured. The fact that there is little change in gloss was used as a measure of the resistance to wrinkle flow. (Drawdown resistance during vacuum forming) The soft sheet obtained above was cut to a width of 2 mm, fixed at two fulcrums separated by 100 mm, and heated at 140 ° C for 2 minutes to measure the amount of droop. A small amount of droop was used as a guideline for drawdown resistance. (Evaluation of uniformity of wall thickness in vacuum formed product) After heating a 0.5 mm thick sheet in an oven at 220 ° C. for 30 seconds, an opening has a length of 300 mm × a width of 200 mm and a bottom has a length of 280.
A box mold having a size of mm × width 180 mm and depth 100 mm was used, and vacuum molding was performed at a mold temperature of 30 ° C. The presence or absence of thickness unevenness of 10 μm or more was observed for this molded product, and this was used as a standard for the uniformity of wall thickness. The melt strength, flexural modulus, shore hardness, gloss change and droop amount of the obtained polypropylene resin composition were measured. The results are shown in Table 1.

[Comparative Examples 1 and 2] The same procedure as in Example 1 was repeated except that no branched polypropylene was used.
It was measured. As is clear from Table 1, the polypropylene resin composition of the present invention has excellent moldability in calendar molding and sheet molding. Further, it is understood that the soft sheet obtained from it is easy to decorate such as graining, has excellent vacuum formability, and is suitable for automobile interior materials.

[0053]

[Table 1]

[0054]

The present invention provides a polypropylene resin composition and a soft sheet for automobile interior materials,
A polypropylene resin composition prepared by blending an uncrosslinked α-olefin copolymer rubber with a polyolefin resin containing a branched polypropylene that is inexpensive and easy to produce,
Not only is it excellent in moldability and easy to decorate, but it also has the advantages that the grain flow and drawdown product thickness are greatly improved. INDUSTRIAL APPLICABILITY The resin composition and the soft sheet according to the present invention can be effectively used not only in automobile interior materials such as door skins, instrument panels, armrests, grips and ceilings but also in other fields such as stationery and sundries.

Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) C08L 23/10-23/16

Claims (5)

(57) [Claims] 1. A polyolefin resin containing polypropylene (a) having a branching index of less than 1.0, having a strain hardening elongational viscosity and having no gel component, and (b) an α-olefin. A composition comprising a polymer rubber, wherein the component (a) is in the range of 15 to 85 parts by weight with respect to a total of 100 parts by weight of the components (a) and (b). . 2. A polypropylene having a branching index of less than 1.0 and having strain-hardening elongational viscosity in the component (a) is 10% by weight or more, and the polypropylene of the components (a) and (b) is It is 3% by weight or more based on the total.
The polypropylene resin composition described. 3. The polypropylene resin according to claim 1 or 2 , wherein the α-olefin copolymer rubber as the component (b) is an ethylene-propylene copolymer rubber or an ethylene-propylene-non-conjugated diene copolymer rubber. Composition. 4. The melt strength measured at 190 ° C. is 15 g or more and the flexural modulus is 4,000 kg.
Claims 1-3 gall and less than / cm ²
Zureka polypropylene resin composition according to item 1. 5. The polypropylene resin composition according to any one of claims 1 to 4 is formed into a sheet by calendar molding or extrusion molding, and then the surface of the sheet is embossed to give a texture. Soft sheet.