JP2002249625A - Polypropylene resin composition for thermoforming and polypropylene resin sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polypropylene resin composition for thermoforming sheets, which shows improved behavior patterns to heat and gives a sheet of a uniform thickness by thermoforming. SOLUTION: The polypropylene resin composition for thermoforming sheets contains a polypropylene resin and a cyclic olefin resin. The above polypropylene resin has a melt flow rate of 0.1-2 g/10 minutes. The above cyclic olefin resin has the glass transition temperature of 100-170 deg.C. The amount of the cyclic polyolefin contained in the composition is 10-100 pts.wt. for 100 pts.wt. of the polypropylene resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polypropylene resin composition for sheet thermoforming, a sheet using the same, and a sheet thermoformed product. More specifically, the present invention relates to a polypropylene resin composition for sheet thermoforming having improved heating behavior such as drooping, a sheet using the same, and a sheet thermoformed product.

[0002]

2. Description of the Related Art Many polypropylene resin molded products widely used as cushioning materials for molding food trays and packing sheets are formed by vacuum molding using polypropylene resin sheets.
It is manufactured by sheet thermoforming such as pressure forming and vacuum pressure forming. In general, when sheet thermoforming is performed using a synthetic resin sheet, the horizontally stretched sheet is heated and sags, resulting in a wavy state, and then `` stretching back '' to a flat state, and then the sheet again sags. This causes the central part to hang down. The polypropylene resin sheet has poor heating behavior such that the time (retention time) from the rebound to the beginning of drooping is short, and the distance from the flat surface of the rebound to the lower end when drooping (dripping amount) is large. have. For this reason, the sheet thermoformed product of the polypropylene resin is likely to have uneven thickness. For example, a phenomenon in which the thickness becomes extremely thin in the case of deep drawing often occurs.

Hitherto, in order to improve the heating behavior of a polypropylene resin sheet, a polymer is partially crosslinked by ionizing radiation irradiation or addition of an organic peroxide, or a polymer is branched to form a entangled structure. Methods for improving the melt tension have been employed. Also, high density polyethylene or other α
-It has been proposed to add an olefin resin (JP-B-61-1460, JP-B-6-89191, etc.). However, according to the method of ionizing radiation irradiation or organic peroxide addition, although the heating behavior is improved, there is a problem that a swell generated at the time of sheet extrusion processing causes a swelling-like substance to adhere to the sheet and impair the appearance. . In addition, when high-density polyethylene or other α-olefin-based resin is added, there is a problem that warpage is generated in the molded product or the strength of the molded product is reduced.

[0004]

SUMMARY OF THE INVENTION Under such circumstances, the present invention provides a polypropylene resin composition which provides a resin sheet having improved heating behavior, which is suitable for sheet thermoforming, a sheet using the same, The purpose is to provide a sheet thermoformed product.

[0005]

Means for Solving the Problems The inventors of the present invention have made intensive studies to solve the above-mentioned problems, and as a result, by blending a polynorbornene resin having a specific glass transition point with a polypropylene resin, the retention time is increased. And the amount of droop is reduced. The present invention has been made based on this finding. That is, the present invention provides (1)
A polypropylene resin composition comprising a polypropylene resin and a cyclic olefin resin, wherein the polypropylene resin has a melt flow rate of 0.2 at a temperature of 230 ° C.
Sheet thermoforming wherein the cyclic olefin resin has a glass transition temperature of 100 to 170 ° C., and the amount of the cyclic olefin resin is 10 to 100 parts by weight based on 100 parts by weight of the polypropylene resin. The polypropylene resin for sheet thermoforming according to the above (1), further comprising (2) an inorganic filler, wherein the blending amount of the inorganic filler is 10 to 100 parts by weight based on 100 parts by weight of the polypropylene resin. The composition, (3) a polypropylene resin sheet for sheet thermoforming comprising the polypropylene resin composition for sheet thermoforming according to (1) or (2), and (4) a polypropylene for sheet thermoforming according to (3). It is intended to provide a polypropylene resin molded product obtained by thermoforming a resin sheet.

[0006]

DETAILED DESCRIPTION OF THE INVENTION The polypropylene resin used in the present invention is a propylene homopolymer or a copolymer having a propylene structural unit of 50% by weight or more and another α-olefin structural unit having 2 to 20 carbon atoms. Here, the copolymer of propylene and an α-olefin having 2 to 20 carbon atoms includes a random copolymer, an alternating copolymer, and the like. These polypropylene resins are usually produced by polymerization using a Ziegler-Natta catalyst or the like.
As the α-olefin, ethylene, 1-butene,
1-pentene, 1-hexene, 3-methyl-1-butene, 3-methyl-1-pentene, 3-ethyl-1-pentene, 4-methyl-1-pentene, 4-methyl-1-hexene, 4, 4-dimethyl-1-hexene, 4,4-dimethyl-1-pentene, 4-ethyl-1-hexene, 3
-Ethyl-1-hexene, 1-octene, 1-decene,
1-dodecene, 1-tetradecene, 1-hexadecene,
1-octadecene, 1-eicosene and the like can be mentioned.
Melt flow rate of polypropylene resin (hereinafter MF)
It may be written as R. ) Is not particularly limited.
The value according to K7210 is 0.1 to 2 g / 10 min, preferably 0.3 to 1.5 g / 10 min, more preferably 0.1 to 2 g / 10 min.
5-1 g / 10 min. If the MFR of the polypropylene resin is too small, the meltability is poor and heat is generated,
It is not preferable because the production of the sheet may be difficult. Conversely, if the MFR is too large, the sheet drips immediately after the exit of the extrusion die during extrusion for sheet production,
Sheet manufacturing can be difficult.

The cyclic olefin resin used in the present invention includes a norbornene resin and a monocyclic olefin resin. The norbornene-based resin is a polymer having a structural unit of a monomer having a norbornene ring structure, and the proportion of the structural unit in the polymer is usually 50% by weight or more, preferably 70% by weight or more, more preferably Is 90% by weight or more. Specific examples of the norbornene resin include, for example, JP-A-3-14882 and JP-A-3-14882.
Known polymers disclosed in, for example, JP-A-122137, include ring-opened polymers of norbornene-based monomers and hydrides thereof, addition polymers of norbornene-based monomers and hydrides thereof, and norbornene An addition copolymer of a system monomer and a monomer capable of being addition-copolymerized therewith is exemplified.

Examples of the norbornene-based monomers include norbornenes having an unsubstituted or alkyl group, such as norbornene, 5-methylnorbornene, 5-ethylnorbornene, and 5-cyclohexylnorbornene; 5-ethylidene norbornene, 5-vinyl norbornene, -Norbornenes having an alkenyl group such as cyclohexenyl norbornene; norbornenes having an aromatic ring such as 5-phenylnorbornene;

5-methoxycarbonylnorbornene, 5
-Methyl-5-ethoxycarbonylnorbornene, norbornenyl-2-methylpropionate, norbornene-5,6-dicarboxylic anhydride, 5,6-di (hydroxymethyl) norbornene, 5,6-dicarboxynorbornene, Norbornenes having a polar group containing an oxygen atom such as methoxycarbonyl-6-carboxynorbornene; 5-cyanonorbornene, norbornene-5,
Examples include norbornenes having a polar group containing a nitrogen atom, such as 6-dicarboxylic imide.

Dicyclopentadiene, tricyclo [4.
3.0.1 ^2,5 ] dec-3-ene; tricyclo [4.4.0.1 ^2,5 ] under-3-ene, tetracyclo [6.5.0.1 ^2,5 . 0 ^8,13] trideca -3,8,10,12- tetraene (1,4-methano -1,4,4a, also referred 9a- tetrahydrofluorene), tetracyclo [6.6.0.1 ^{2, 5.} 0
^{8, 13]} tetradeca -3,8,10,12- tetraene (1,4-methano -1,4,4a, 5,10,10a
Norbornene derivatives having an aromatic ring, such as -hexahydroanthracene);

Unsubstituted or alkyl-containing tetracyclododecenes such as tetracyclododecene, 8-methyltetracyclododecene, 8-cyclohexyltetracyclododecene and 8-cyclopentyltetracyclododecene; 8-methylidene Tetracyclododecenes having a double bond outside the norbornene ring, such as tetracyclododecene, 8-cyclohexenyltetracyclododecene, and 8-cyclopentenyltetracyclododecene; aromatic rings such as 8-phenyltetracyclododecene Tetracyclododecenes having:

8-methoxycarbonyltetracyclododecene, 8-methyl-8-methoxycarbonyltetracyclododecene, 8-hydroxymethyltetracyclododecene, 8-carboxytetracyclododecene, tetracyclododecene-8,9 Tetracyclododecenes having a substituent containing an oxygen atom, such as dicarboxylic acid and tetracyclododecene-8,9-dicarboxylic anhydride; 8-cyanotetracyclododecene, tetracyclododecene-8,9
Tetracyclododecenes having a substituent containing a nitrogen atom such as dicarboxylic imide; tetracyclododecenes having a substituent containing a halogen atom such as 8-chlorotetracyclododecene; 8-trimethoxysilyltetracyclo Tetracyclododecenes having a substituent containing a silicon atom such as dodecene;

Hexacycloheptadecene, 12-methylhexacycloheptadecene, 12-ethylhexacycloheptadecene, 12-cyclohexylhexacycloheptadecene, 12-cyclopentylhexacycloheptadecene, etc. Heptadecenes; 12-methylidenehexacycloheptadecene, 12-vinylhexacycloheptadecene, 1
Hexacycloheptadecenes having a double bond outside the ring, such as 2-cyclopentenylhexacyclohexadecene;
Hexacycloheptadecenes having an aromatic ring such as 12-phenylhexacycloheptadecene;

12-methoxycarbonylhexacycloheptadecene, 12-methyl-12-methoxycarbonylhexacycloheptadecene, 12-hydroxymethylhexacycloheptadecene, 12-carboxyhexacycloheptadecene, hexacycloheptadecene-12,1
3-dicarboxylic acid, hexacycloheptadecene-12,
Hexacycloheptadecenes having a substituent containing an oxygen atom such as 13-dicarboxylic anhydride; 12-cyanohexacycloheptadecene, hexacycloheptadecene-
Hexacycloheptadecenes having a substituent containing a nitrogen atom such as 12,13-dicarboxylic imide; hexacycloheptadecenes having a substituent containing a halogen atom such as 12-chlorohexacycloheptadecene; 12-
Hexacycloheptadecenes having a substituent containing a silicon atom, such as trimethoxysilylhexacycloheptadecene, and the like.

Of these, those having a tricyclic or tetracyclic structure are preferred. Among them, dicyclopentadiene, tricyclo [4.3.0.1 ^2,5 ] -dec-3-ene and tetracyclo [6.5. 0.1 ^2,5 . 0 ^8,13] trideca -3,8,10,12- tetraene, tetracyclo [6.6.0.1 ^2,5. 0 ^8,13] tetradeca -
3,8,10,12-Tetraene, tetracyclododecene and 8-methyltetracyclododecene are more preferred, and dicyclopentadiene is particularly preferred.

The above norbornene monomers can be used alone or in combination of two or more. Specific examples of the monomer that can be addition-copolymerized with the norbornene-based monomer include α-olefin and propylene exemplified as the copolymerized monomer in the above polypropylene resin; 1,4-hexadiene, 4-methyl- 1,4
-Hexadiene, 5-methyl-1,4-hexadiene,
Examples include non-conjugated diene compounds such as 1,7-octadiene and the following monocyclic olefin monomers.
These copolymerizable monomers can be used alone or in combination of two or more.

The monocyclic olefin resin is a polymer having a structural unit of a monocyclic olefin monomer, and the proportion of the structural unit in the polymer is usually 50% by weight or more.
Preferably 70% by weight or more, more preferably 90% by weight
That is all. Specific examples of the monocyclic olefin resin include a ring-opened polymer of a monocyclic olefin monomer and a hydrogenated product thereof, an addition polymer of a monocyclic olefin monomer,
An addition copolymer of a monocyclic olefin monomer and a monomer capable of addition copolymerization with the monocyclic olefin monomer is exemplified.

The monocyclic olefin monomer includes cyclobutene, cyclopentene, cyclohexene, 3,4-
Dimethylcyclopentene, 3-methylcyclohexene,
2- (2-methylbutyl) -1-cyclohexene, cyclooctene, 3a, 5,6,7a-tetrahydro-4,
Cyclomonoolefins such as 7-methano-1H-indene; cyclohexadiene, methylcyclohexadiene,
Cyclodiolefins such as cyclooctadiene, methylcyclooctadiene, and phenylcyclooctadiene; bicyclo [3.3.0] octene, tricyclo [5.2.
1.0 ^2,6 ] dec-3-ene, bicyclo [4.3.
0] nona-3,7-diene and the like.
Examples of the monomer capable of ring-opening copolymerization with the monocyclic olefin monomer include the above-mentioned norbornene-based monomers. Examples of the monomer that can be addition-copolymerized with the monocyclic olefin monomer include the above-mentioned norbornene-based monomers and the α-olefins and non-conjugated diene compounds exemplified as the copolymerizable monomers thereof.

In order to obtain a ring-opening polymer using the norbornene-based monomer or the monocyclic olefin monomer, a metal halide such as ruthenium, rhodium, palladium, osmium, iridium, platinum or the like is used as a ring-opening polymerization catalyst. Using a catalyst comprising a nitrate or acetylacetone compound and a reducing agent, or a catalyst comprising a metal halide or acetylacetone compound such as titanium, vanadium, zirconium, tungsten or molybdenum, and an organoaluminum compound, in a solvent or No solvent, usually at a polymerization temperature of -50 ° C to 100 ° C, 0 to 5M
Ring-opening polymerization is performed at a polymerization pressure of Pa. In order to obtain a hydrogenated product of these ring-opened (co) polymers, the ring-opened (co) polymer is hydrogenated by a conventional method using hydrogen in the presence of a hydrogenation catalyst such as nickel, palladium or platinum. I do.

The addition polymer of a norbornene-based monomer or a monocyclic olefin monomer and the addition copolymer of these with the copolymerizable monomer may be prepared, for example, by adding a monomer component in a solvent or without a solvent. In a solvent, in the presence of a catalyst consisting of a titanium, zirconium, or vanadium compound and an organoaluminum compound, it is usually obtained by a method of copolymerizing at a polymerization temperature of −50 ° C. to 100 ° C. and a polymerization pressure of 0 to 5 MPa. it can.

The glass transition temperature of the cyclic olefin resin used in the present invention (hereinafter sometimes referred to as “Tg”).
Is 100 to 170 ° C, preferably 110 to 160 ° C,
More preferably, it is 120 to 150 ° C. If Tg is too low, the amount of sheet droop may increase.
If the value of g is too high, the mold followability (shapeability) of the sheet may be reduced. The average molecular weight of the cyclic olefin resin used in the present invention is appropriately selected according to the purpose of use, but the weight average in terms of polystyrene measured by gel permeation chromatography (GPC) using chloroform as a solvent. The molecular weight (hereinafter sometimes referred to as “Mw”) is usually 5,000 to 1,000,000.
0, preferably 8,000 to 500,000, more preferably 10,000 to 200,000.

In the present invention, the mixing ratio of the polypropylene resin and the cyclic olefin resin is 10 to 10 parts by weight of the polypropylene resin and 10 to 10 parts by weight of the cyclic olefin resin.
100 parts by weight, preferably 30 to 80 parts by weight, more preferably 40 to 70 parts by weight. If the amount of the cyclic olefin resin is too small, the amount of hanging of the sheet may increase,
If the amount of the cyclic olefin resin is too large, the strength of the molded article may be reduced.

The composition of the present invention may contain a filler, if necessary.
Additives such as an ultraviolet absorber, a light stabilizer, an antioxidant, an antistatic agent, and a foaming agent can be added. Among the fillers, inorganic fillers are preferred. As the inorganic filler, talc,
In addition to natural inorganic substances such as silica, clay and mica, oxides such as titanium oxide, iron oxide, zinc oxide, magnesium oxide and alumina; silicates such as sodium silicate and calcium silicate; carbonates such as calcium carbonate and magnesium carbonate; Fine powders such as hydroxides such as aluminum hydroxide, magnesium hydroxide and basic calcium carbonate can be used alone or in combination of two or more. Particularly, fine talc having a particle size of 1 to 50 μm and calcium carbonate alone or a mixture thereof are preferable.

In the present invention, the inorganic filler further improves the heating behavior during sheet thermoforming, has the effect of reducing costs, improves the strength of the resin molded product, and reduces the calorific value of combustion when incinerated after use. Has the effect of suppression. The amount of the inorganic filler is usually 10 to 100 parts by weight, preferably 30 to 80 parts by weight, based on 100 parts by weight of the polypropylene resin.
Parts by weight, more preferably 40 to 70 parts by weight. If the amount of the inorganic filler is too small, there is no reinforcing effect of the sheet, and there is a risk that the combustion furnace may be damaged due to a high calorie burned during incineration of waste. Conversely, if the amount of the inorganic filler is too large, heat generation during extrusion molding may increase, leading to deterioration of the resin or deterioration of the shapeability of the sheet.

In order to obtain the polypropylene resin composition for sheet thermoforming and the polypropylene resin sheet for sheet thermoforming of the present invention, first, a polypropylene resin in the form of pellets and a cyclic olefin resin are further added, if necessary. Additives (excluding the foaming agent at this stage) are combined and uniformly mixed in a dry mixer such as a tumbler mixer, Henschel mixer, ribbon blender, etc. A molding material for the composition. The obtained dry mixture may be subsequently melt-mixed with an extruder and pelletized, and this may be used as the molding material. Pelletization is preferable from the viewpoint of ensuring uniformity.

In the case of blending a foaming agent, the foaming agent is uniformly mixed with the above-mentioned molding material by the above-mentioned dry mixer to obtain a foam molding material for sheet thermoforming. Next, each of the above molding materials is supplied to a sheet molding extruder. In the extruder, the material is controlled to a barrel temperature of 180 to 270 ° C. and sent to a die portion of a die such as a T die or a circular die. The material is heated at a temperature of 170-230 ° C and a pressure of 1-10MP at the base.
Extrude as a sheet while controlling to a. The thickness of the thus obtained polypropylene resin sheet for thermoforming of the present invention is usually 0.2 to 2 mm, preferably 0.5 to 1.
8 mm, more preferably 0.7 to 1.5 mm.

A polypropylene resin molded article can be obtained by subjecting the polypropylene resin sheet of the present invention to sheet thermoforming (including vacuum forming, pressure forming and vacuum pressure forming). The method of vacuum forming, pressure forming, and vacuum forming is not limited, and a known forming method can be used. As an example of sheet thermoforming, in order to perform vacuum forming using a female mold, for example, first hold the sheet horizontally with a clamp, heat it with a heater to soften it, put it on the mold, and put it on the outer edge of the mold. Tightly adheres to the sheet (air tight)
Then, the air is evacuated from the back side of the mold by a vacuum pump, whereby air between the mold and the sheet is sucked from the pores in the concave portion, and the sheet is brought into close contact with the mold, cooled and solidified. Remove the sheet from the mold and trim the clamp holder. To perform vacuum forming using a male mold, for example, after pushing up the male mold convex part from below on the softened sheet held horizontally by a clamp, air tight the sheet peripheral part and the substrate part of the outer edge of the mold, Then, the air is exhausted from the back side of the male mold by a vacuum pump, so that air between the mold and the sheet is sucked from the pores at the outer edge of the male convex portion, and the sheet is brought into close contact with the mold, cooled and solidified.

In order to perform air pressure molding using a female mold, for example, a softened sheet is placed on a female mold, and then a deep lid-shaped air box having an outer peripheral wall is placed thereon, and the sheet is placed on the outer peripheral wall. The sheet is air-tight sandwiched between the mold outer edge substrates, and compressed air is supplied to the compressed air box, whereby the sheet is brought into close contact with the mold and cooled and solidified. The pressure of the compressed air is about 0.3 to 0.5 MPa. As an example of vacuum pressure forming using a female mold, almost the same as the above operation, at the same time as sending compressed air to the compressed air box, exhausting from the back side of the mold with a vacuum pump, An operation of sucking air between the mold and the sheet is added.

In the polypropylene resin molded article of the present invention formed by sheet thermoforming, the heating behavior during sheet thermoforming is improved, the holding time is prolonged, and the amount of droop is reduced, so that drawing can be performed uniformly. Performed with less thickness unevenness. Examples of uses of the polypropylene resin molded article of the present invention formed by sheet thermoforming include cushioning materials for assorted products such as soaps and cans; buffers for foods such as eggs and fruits; trays for pastries such as chocolates and cookies; Blister packages for toys and daily necessities; storage trays for small home appliances and electronic device parts.

[0040]

Next, the present invention will be described in more detail by way of examples, which should not be construed as limiting the present invention. Parts and percentages are by weight unless otherwise specified. (1) Retention time Extrude a polypropylene resin sheet, flow direction 300m
m, cut into a rectangle 200 mm in a direction perpendicular to the extrusion flow, and a 5 mm-thick iron plate frame (external dimensions 300 mm x 200 m
m, inner dimensions 250 mm × 150 mm) and fixed horizontally in an electric oven at a temperature of 175 ° C. while being fixed between two sheets. The heated sheet eventually sags and undulates, after which the wrinkles disappear and "rebound" back to the flat state. The time from when the sheet was stretched back until the center part sagged again and began to drop was measured as the "holding time". Unit "second". (2) Droop Amount The distance from the rebound plane to the lower end of the droop 5 seconds after the elapse of the holding time in (1) above was measured as the “droop amount”. Unit "mm".

(3) Thickness ratio The ratio of the thickness at the center of the inner wall surface to the thickness at the center of the bottom surface of each concave portion of a vacuum-formed product having four concave portions obtained by vacuum-forming one polypropylene resin sheet is shown. And averaged. As the thickness of the wall surface of each concave portion, the thickness at the center of each of the four wall surfaces was measured for each concave portion, and the average value thereof was used.
The thickness was measured with a micrometer after cutting the relevant portion with scissors. The closer the thickness ratio is to 1, the more uniform the thickness.

Examples 1 to 5 and Comparative Examples 1 to 5 The types and amounts of the components shown in Table 1 were mixed in a dumb-type mixer, and an extruder [TEM-35B, manufactured by Toshiba Machine Co., Ltd., barrel temperature 230 C., a 3 mm diameter, 4-hole pellet die at 230 ° C.] to produce pellets. The pellets were supplied to a 65 mm extruder (L / D = 29, non-vented, manufactured by Hitachi Zosen Corporation), and the width of 4
A sheet having a thickness of 00 mm and a thickness of 0.7 mm was obtained. The holding time and the amount of droop of this sheet were measured. Next, the sheet is held horizontally by a clamp, placed in an oven, softened at a temperature of 170 ° C., and a vacuum forming machine [FK-0531-
D, manufactured by Asano Laboratory Co., Ltd.] under vacuum pressure of 760 mmHg and cooling time of 15 seconds to obtain a vacuum-formed product. Outer dimensions are 420mm long and 4mm wide
A female mold was used in which four concave portions were arranged in a square shape on the upper surface of an aluminum mold having a height of 20 mm and a height of 55 mm. The recess has a dimension of 150 mm in length, 150 mm in width, 40 mm in depth, a draft angle of 5 °, and an inner wall bottom having a curved surface with a radius of 3 mm. Is also 40 mm. The thickness ratio of the obtained vacuum-formed product (one having four concave portions arranged in a square shape) was measured. Table 1 shows the test results of the holding time, the amount of hanging, and the thickness ratio.

[0043]

[Table 1]

Note * 1: HT1050, manufactured by Chisso Corporation, propylene homopolymer, MFR 0.5 g / 10 min. * 2: BC8A, manufactured by Nippon Polychem Co., Ltd., propylene-ethylene block copolymer, propylene structural unit about 8
5% by weight, MFR 0.7 g / 10 min. * 3: XF1800, manufactured by Chisso Corporation, propylene-
Ethylene random copolymer, propylene structural unit about 95
% By weight, MFR 1.8 g / 10 min. * 4: ZEONEX 480, manufactured by Zeon Corporation, cyclic olefin resin, Tg 140 ° C, Mw about 40,00
0. * 5: Zeonor 1600, manufactured by Zeon Corporation, cyclic olefin resin, Tg 160 ° C, Mw about 33,000. * 6: Zeonor 1420, manufactured by Zeon Corporation, cyclic olefin resin, Tg 142 ° C, Mw about 35,000. * 7: Talc MSZ, manufactured by Nippon Talc Corporation, average particle size 5 μm.

As shown in Table 1, the holding time of the polypropylene resin composition for sheet thermoforming of the present invention was longer than that in the case where the cyclic olefin resin was not added, and the amount of droop was reduced. Reduced, thickness ratio 1
(Comparative Example 1 and Comparative Example 1, Comparative Example 2 and Comparative Example 2, Comparative Example 3 and Comparative Example 3, Comparative Example 4)
And Comparative Example 4). When the inorganic filler is blended in the mixed system of the polypropylene resin and the cyclic olefin resin, the holding time is further extended, the amount of droop is reduced, and the heating behavior is improved,
The thickness ratio was even closer to 1 (compared to Example 4 and 5).
Further, the heating behavior was hardly improved only by blending the inorganic filler with the polypropylene resin (Comparative Example 5).
And 1).

According to the present invention, there is provided a polypropylene resin composition for sheet thermoforming, wherein the heating behavior is improved and a sheet thermoformed product having a uniform thickness is obtained.

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Claims (4)

[Claims] 1. A polypropylene resin composition comprising a polypropylene resin and a cyclic olefin resin, wherein the polypropylene resin has a melt flow rate at 230 ° C. of 0.1 to 2 g / 10 min. Glass transition temperature 100-1
70 ° C., wherein the amount of the cyclic olefin resin is 10 to 100 parts by weight based on 100 parts by weight of the polypropylene resin. 2. The polypropylene resin composition for sheet thermoforming according to claim 1, further comprising an inorganic filler, wherein the amount of the inorganic filler is 10 to 100 parts by weight based on 100 parts by weight of the polypropylene resin. 3. A polypropylene resin sheet for thermoforming a sheet, comprising the polypropylene resin composition for thermoforming a sheet according to claim 1 or 2. 4. A polypropylene resin molded product obtained by sheet thermoforming the polypropylene resin sheet for sheet thermoforming according to claim 3.