JPH08134230A - Mar-resistant polypropylene resin sheet and production thereof - Google Patents

Abstract

PURPOSE: To produce at a high molding speed a sheet which has high marring resistance and a satisfactory hue, is excellent especially in optical properties (transparency and gloss), appearance (surface smoothness), and mechanical properties, and does not suffer heat deterioration even when thick. CONSTITUTION: The sheet is obtained from a composition comprising: 100 pts.wt. resin component consisting mainly of a propylene polymer; 0.01-0.5 pts.wt. phosphorus compound antioxidant and/or 0.01-0.5 pts.wt. phenolic antioxidant; and 0.01-0.5 pts.wt. glycerol/fatty acid ester and/or 0.01-0.5 pts.wt. fatty acid amide.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polypropylene resin sheet having excellent scratch resistance and transparency, and a method for producing the same. Specifically, it is a sheet used for applications such as thermoformed containers for food, lids, trays, blister packs, stationery files, folded products such as clear cases, pharmaceutical tablets, PTP (press through pack) for food, etc. It is a sheet with excellent optical properties, mechanical properties, etc., and excellent scratch resistance on the surface of the sheet.
The present invention relates to a polypropylene resin sheet excellent in mechanical properties, scratch resistance and the like, and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, as a general method for improving the transparency of a polypropylene sheet, a method of rapidly cooling the polypropylene sheet, a method of controlling crystallization by adding a nucleating agent, etc. are known. For example, a method for producing a transparent polypropylene sheet having a smectic structure by blending crystalline polypropylene with an alicyclic petroleum resin or the like and quench-molding (JP-A-51-91955 and JP-A-55-27203).
Japanese Patent Laid-Open Publication No. 1985-1988), a method of modifying polypropylene by adding a sorbitol-based nucleating agent to crystalline polypropylene (JP-A-56-
No. 45934), a method of rolling a polypropylene original fabric containing an orientation accelerator melt-extruded from a T-die (Japanese Patent Laid-Open No. 5-539).
8-185224 gazette) etc. are proposed. However, these methods have a problem that if the sheet thickness becomes thick, uniform cooling is not performed and the optical characteristics are not improved. Further, as a method for molding a polypropylene sheet, there are conventionally known an air knife method, a polishing roll method and the like. However, in the air knife method, since the sheet is simply pressure-bonded to the roll by air pressure, uneven thickness and smoothness of the sheet cannot be corrected, and rapid cooling cannot be performed, so that the sheet does not become a highly transparent sheet. Also, the molding speed is slow,
Not suitable for thick sheets. On the other hand, the polishing roll method is a method of pressing a film-like molten resin extruded from a T-die with a tangent line of a pair of metal rolls to form a sheet. It is difficult to increase the molding speed because it is only sandwiched by the tangents, and rapid cooling cannot be performed, so that a highly transparent sheet cannot be obtained. Further, as a method of forming a polypropylene sheet having excellent transparency, a method of rapidly forming a polypropylene film by a special water cooling device (Japanese Patent Laid-Open No. 61-
189920), a method for producing a transparent sheet by introducing the belt between a metal endless belt and a cooling roll (Japanese Patent Application Laid-Open No. H5-1993).
No. 286020, JP-A-6-55613) and the like have been proposed. However, although the optical characteristics are improved by these methods, there is a drawback in that when the molten resin is cooled with water, horizontal stripes are generated on the sheet due to waviness when the sheet is drawn into water. Further, due to the recent improvement in productivity, it cannot be said that the demand for producing a thick sheet at a higher speed, a higher mechanical strength and a highly transparent sheet is sufficiently satisfied. Further, the sheet having a polypropylene polymer as a main component has a drawback that the higher the transparency, the more easily the surface of the sheet is scratched. That is, when the sheets are rubbed against each other or the surface of the sheet is rubbed with cloth, paper, or the like, scratches remain on the surface of the sheet. As a method for improving the scratch resistance of a sheet containing a polypropylene-based polymer as a main component, JP-A-61-118448, JP-A-63-17947 and JP-A-5-163393 are disclosed.
As described in the publication, polystyrene, a rubber-like substance, a methacrylic resin or the like is blended with a polypropylene polymer. However, such a method may result in insufficient transparency of the sheet or high cost.

[0003]

DISCLOSURE OF THE INVENTION The object of the present invention is to have good scratch resistance, and further, to obtain a thick sheet without thermal deterioration, good hue, high speed molding, and optical characteristics (transparency, transparency, The present invention provides a polypropylene resin sheet having remarkably excellent glossiness, appearance characteristics (surface smoothness) and mechanical characteristics, and a method for producing the same.

[0004]

Means for Solving the Problems In view of the above problems, the inventors of the present invention have made extensive studies, and as a result, by using a specific polypropylene resin composition, a polypropylene-based resin having markedly excellent scratch resistance is obtained. It was found that a sheet could be obtained. It was found that the effect was greater as the transparency of the sheet was better, and the present invention was completed. That is,
The present invention relates to (1) 0.01 to 0.5 parts by weight of a phosphorus-based antioxidant and / or 0.01 parts of a phenol-based antioxidant with respect to 100 parts by weight of a resin component containing a polypropylene polymer as a main component. To 0.5 parts by weight, (2) 0.01 to 0.5 parts by weight of glycerin fatty acid ester and / or 0.01 to 0.5 parts by weight of fatty acid amide, and made of a scratch-resistant polypropylene resin. It is a sheet. The present invention also provides (1) 0.01 to 0.5 parts by weight of a phosphorus-based antioxidant and / or 0 a phenol-based antioxidant with respect to 100 parts by weight of a resin component containing a polypropylene polymer as a main component. 0.01 to 0.5 parts by weight, (2) glycerin fatty acid ester 0.01 to 0.5 parts by weight and /
Alternatively, a film-shaped molten resin is extruded from at least (A) T die using a composition containing 0.01 to 0.5 part by weight of fatty acid amide and (3) 0.02 to 1.0 part by weight of a nucleating agent. ,
(B) A sheet obtained by sandwiching the film-like molten resin between a cast roll and an endless belt formed in an arc shape along the roll, the sheet comprising:
(D): (a) thickness of 0.05 to 2.0 mm, (b) transparency (clarity) of 65% or more, (c) transparency (haze) of 15% or less, (d) bending stiffness of 7500. ~ 25
A method for producing a scratch-resistant polypropylene resin sheet, which is characterized by satisfying a property of 000 Kgf / cm ² .

The present invention will be described in detail below. The resin component in the present invention is at least one selected from a mixed composition of 100 to 50% by weight of polypropylene polymer and 50% by weight of polyethylene polymer. If the blending amount of the polyethylene-based polymer exceeds 50% by weight, the rigidity of the sheet decreases and the sheet becomes soft, which is not preferable. The melt flow rate (MFR) of the resin component is 0.
1-10 g / 10 minutes, preferably MFR 0.5-8 g /
It is desirable to select in the range of 10 minutes. If the MFR is less than 0.1 g / 10 min, the extrusion processability is poor, and if the MFR exceeds 10 g / 10 min, drawdown occurs during sheet molding or thermoforming of the sheet, which is not preferable.

The polypropylene-based polymer used in the present invention is a propylene homopolymer or a copolymer containing propylene as a main component and α-olefin, specifically, a propylene-ethylene block copolymer or a propylene-polymer. Examples thereof include ethylene random copolymers and mixtures thereof. The melt flow rate (MFR) of the polypropylene polymer is 0.1 to 10 g / 10 minutes, preferably 0.
3 to 8 g / 10 minutes, more preferably 0.5 to 5 g / 1
0 minutes. If the MFR is less than 0.1 g / 10 minutes, extrusion processing will be poor, and if it exceeds 10 g / 10 minutes, drawdown will occur during sheet forming or thermoforming of the sheet, which is not preferable. Among these, a propylene homopolymer is preferable when the mechanical strength is emphasized, and a propylene-ethylene random copolymer is preferable when the transparency is emphasized. Further, in order to maintain both properties of mechanical strength and transparency in a well-balanced manner, it is preferable to mix the propylene homopolymer at 95 to 70% by weight and the propylene-ethylene random copolymer at 5 to 30% by weight. . The polypropylene homopolymer preferably has a boiling n-heptane insoluble content of 92 to 99% by weight. More preferably, it is 94 to 98% by weight.
The ethylene content of the propylene-ethylene random copolymer is 0.3 to 10% by weight, preferably 1 to 7% by weight.

The polyethylene polymer used in the present invention includes high-medium density polyethylene (HDPE, MDPE), linear low-density polyethylene (LLDPE), ultra-low-density polyethylene (VLDPE) and low-density polyethylene (LDP).
E), ethylene- (meth) acrylic acid alkyl ester copolymers such as ethylene-vinyl acetate copolymer (EVA) and ethylene-ethyl acrylate copolymer (EEA). The density of these polyethylene-based polymers is 0.88 to 0.97 g / cm ³ , preferably 0.89 to
0.94 g / cm ³ , melt flow rate (MFR)
Is 0.1-10 g / 10 minutes, preferably 0.3-0.
7 g / 10 minutes, more preferably 0.3 to 5.0 g / 1
0 minutes. Among these, LDPE, LLDPE,
VLDPE is preferred.

The phosphorus-based antioxidant used in the present invention is preferably an antioxidant in which phosphorus is an organic compound having a phosphite structure or a phosphonite structure, and is not particularly limited. It is preferably at least one selected from the following compounds.
That is, as the organic phosphite antioxidant,
Tris (dibutylphenyl) phosphite (trade name:
Irgafos 168, manufactured by Ciba Geigy), cyclic neopentatetrayl bis (octadecyl phosphite) (trade name: ADEKA STAB PEP-8M, manufactured by Asahi Denka Kogyo KK), bis (2,4-di-t-butylphenyl) penta Erythritol diphosphite (trade name: ADEKA STAB PEP-24G, manufactured by Asahi Denka Co., Ltd .; brand name: Ultranox 626, manufactured by General Electronics Co., Ltd.), tris (mixed mono and genonylphenyl) phosphite (trade name: ADEKA STAB 329K,
Asahi Denka Kogyo Co., Ltd., and the like, and particularly tris (dibutylphenyl) phosphite is preferable. Examples of the organic phosphonite-based antioxidant include tetrakis (2,4-di-t-butylphenyl) 4,4'-biphenylenediphosphinate (trade name: Sandstab P-EPQ, manufactured by Sand Co.). To be The amount of the antioxidant added is 0.01 to 0.5 parts by weight based on 100 parts by weight of the resin component,
The amount is preferably 0.03 to 0.2 parts by weight, and if the amount of the antioxidant added is less than 0.01 parts by weight, the antioxidant effect cannot be obtained, the MFR of the sheet increases, and it is It is not preferable because drawdown of the sheet occurs during molding. Further, even if the addition amount exceeds 0.5 parts by weight, the effect is not improved and the cost becomes high.

The phenolic antioxidant used in the present invention is not particularly limited, but is preferably at least one selected from the following compounds. Specifically, tetrakis (methylenedibutylhydrokyanite) methane (trade name: Irganox 1010, manufactured by Ciba Geigy), 1,3,5-trimethyl-2,4,6-
Tris (3,5-di-t-butyl-4-hydroxyl)
Benzene (trade name: Irganox 1330, manufactured by Ciba Geigy), octadecyl butyl hydroxy hydrocyanite (trade name: Irganox 1076, manufactured by Ciba Geigy), particularly tetrakis (methylenedibutylhydrokyanite) methane, 1,3,5- Trimethyl-2,
4,6-Tris (3,5-di-t-butyl-4-hydroxyl) benzene is preferred. The amount of the antioxidant added is 0.01 to 0.5 part by weight, preferably 0.03 to 0.2 part by weight, based on 100 parts by weight of the resin component. If the amount is less than 0.01 parts by weight, the antioxidant effect cannot be obtained, the MFR of the sheet increases, and drawdown of the sheet occurs during sheet molding or thermoforming, which is not preferable. Further, the effect is not improved even if the amount added exceeds 0.5 part by weight, resulting in high cost. The phosphorus-based antioxidant and the phenol-based antioxidant may be used alone, but the combined use increases the antioxidant effect.

The glycerin fatty acid ester used in the present invention is usually called monoglyceride, and stearic acid monoglyceride (melting point: about 65 ° C.), oleic acid monoglyceride (melting point: about 40 ° C.), linoleic acid monoglyceride and the like are used in the present invention. However, stearic acid monoglyceride is used particularly effectively. The fatty acid amides used in the present invention are unsaturated fatty acid amides and saturated fatty acid amides, and the unsaturated fatty acid amides include oleic acid amide (melting point 72 to 77 ° C.) and erucic acid amide (melting point 7
9 to 84 ° C.) and the like, and saturated fatty acid amides include stearic acid amide (melting point 99 to 105 ° C.), behenic acid amide (melting point 105 to 115 ° C.) and the like. further,
In the present invention, an unsaturated fatty acid amide having a melting point of 90 ° C. or lower is preferable, and oleic acid amide can be effectively used. The amount of glycerin fatty acid ester and / or fatty acid amide added is 0.01 to 0.5 parts by weight, preferably 0.03 parts by weight, per 100 parts by weight of the resin component.
Is 0.35 parts by weight, and if the addition amount is less than 0.01 parts by weight, the effect of scratch resistance cannot be obtained, which is not preferable. Further, even if the addition amount exceeds 0.5 parts by weight, the effect is not improved and, conversely, the amount of bleeding on the surface of the sheet increases, which causes adverse effects such as stickiness, which is not preferable.

The nucleating agent used in the present invention is preferably at least one selected from talc, an organic carboxylic acid or a metal salt thereof, an organic phosphate metal salt, and a sorbitol compound. Examples of the metal salt of the organic carboxylic acid include aluminum hydroxydi (t-butylbenzoate) (trade name: Al-PTBBA, manufactured by Shell Chemical Co.). Examples of the organic phosphoric acid metal salt include bis (4-t-butylphenyl) sodium phosphate (trade name: ADEKA STAB NA-10, manufactured by Asahi Denka Co., Ltd.), phosphoric acid-2,
2'-methylenebis (4,6-di-t-butylphenyl) sodium (trade name: ADEKA STAB NA-11, manufactured by Asahi Denka Kogyo Co., Ltd.) and the like. As the sorbitol-based compound, 1,3,2,4-di (P-methylbenzylidene) sorbitol (trade name: Gelol MD, Gelol MDR, manufactured by Shin Nippon Rika Co., Ltd.), 1, 2, 2, 4-
Dibenzylidene sorbitol (trade name: EC-1, manufactured by EC Chemical Co., Ltd.), 1, 3, 2, 4-di (P-ethylbenzylidene) sorbitol (trade name: NC-4, manufactured by Mitsui Toatsu Chemical Co., Inc.), etc. It is preferable to use a sorbitol-based compound when the transparency of the sheet is prioritized, and an organic phosphoric acid metal salt is used when the rigidity is prioritized. ADEKA STAB NA-21 (trade name: manufactured by Asahi Denka Kogyo Co., Ltd.) is a nucleating agent having a balance of transparency and rigidity, and is preferably used in the present invention. The amount of the nucleating agent added is 0.02 to 1.0 part by weight, preferably 0.05 to 0.4 part by weight, based on 100 parts by weight of the resin component, and the amount of the nucleating agent added is 0. If it is less than 0.02 part by weight, transparency cannot be obtained, and if it is added in an amount of more than 1.0 part by weight, the effect is not improved and the cost becomes high.

Since the recent polypropylene-based polymers and polyethylene-based polymers used in the present invention have not undergone the catalyst removal step, generally, an acidic catalyst component is present in a trace amount, so it is desirable to add an acid absorbent. Be done. Examples of the acid absorber include metal salts of Group I of higher fatty acids, Group II metal salts of higher fatty acids, and hydrotalcites. The higher fatty acid Group I metal salt of the periodic table includes lithium stearate, potassium stearate, sodium stearate and the like, and the higher fatty acid Group II metal salt of the periodic table includes calcium stearate and stearic acid. Examples include zinc. In addition, specific examples of hydrotalcites include trade name: DHT
-4A (made by Kyowa Chemical Co., Ltd.) is mentioned. The amount of the acid absorbent added is 0.005 to 100 parts by weight of the resin component.
It is 0.5 part by weight, preferably 0.05 to 0.2 part by weight. If the addition amount of the acid absorbent is less than 0.005 part by weight, the acid absorbing effect is not exerted, which may cause corrosion of the molding machine. Moreover, even if the addition amount exceeds 0.5 parts by weight,
It is not preferable because further improvement of the effect cannot be expected and the cost becomes high.

The transparent polypropylene resin sheet of the present invention is produced by using the above composition to extrude at least (A) a film-shaped molten resin from a T die, and (B) use the film-shaped molten resin as a cast roll. It can be obtained by pinching with an endless belt formed in an arc shape along the roll.

The sheet manufacturing method of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a schematic manufacturing process diagram of one embodiment of the sheet of the present invention, which mainly comprises (A) an extrusion process of extruding a film-like molten resin from a T die provided in an extruder,
(B) A first cooling step of sandwiching the film-like molten resin between a cast roll and an endless belt formed in an arc shape along the roll, and (C) rapidly cooling with a cooling medium such as water cooling. The second cooling step, (D) annealing step, (E) winding step or (F) cutting step (not shown), etc.,
It is commercialized through these steps. FIG. 2 is an enlarged view of (B) a first cooling step in which the film-like molten resin is pressed between a cast roll and an endless belt formed in an arc shape along the roll.

The first cooling step and the like shown in FIG. 2 will be described below. In the extrusion step of FIG. 1, a predetermined polypropylene resin is supplied from an extruder raw material charging port, and the film-shaped molten resin 2 extruded from the T die 1 at the tip of the extruder is the first
A sheet 9 is formed by being pinched by the arc-shaped pinching portion 8 between the cast roll 3 in the cooling step and the endless belt 4 formed in an arc shape along the roll. The endless belt 4 is engaged with the roll 5, the roll 6 and the roll 7 so that the endless belt 4 follows the cast roll 3 in an arc shape, the tension can be controlled, and the distance between the cast roll 3 and the roll 5 can be controlled. The thickness of the sheet 9 obtained by the distance is adjusted. Further, by moving the position of the roll 6, the distance along which the roll 6 is curved can be adjusted. The temperatures of the cast roll 3 and the endless belt 4 formed in an arc shape along the roll are not higher than the softening temperature of the polypropylene resin and not lower than the glass transition temperature, preferably 30 to 110 ° C. That is, the cast roll 3 and the endless belt 4 are kept below the softening temperature of the polypropylene-based resin and above the glass transition temperature by the roll 5 and the roll 7 which are heated from the inside with heating oil or the like or cooled by a refrigerant as necessary. ing. Next, the sheet 9 delivered from the arcuate pressing portion 8 is preferably secondarily cooled in the water tank of the second cooling step. The temperature during the secondary cooling is controlled by setting the temperature of the cast roll 3 and the endless belt 4 within the softening temperature of the polypropylene resin, preferably in the temperature range from the heat distortion temperature of the polypropylene resin to the softening temperature. . If the temperature exceeds the softening temperature, the sheet is too soft and the peelability from the cast roll 3 or the endless belt 4 decreases,
There is a possibility that minute scratches frequently occur on the surface of the sheet or wrinkles occur in a later step, and a good sheet cannot be formed. The material of the cast roll 3 and / or the endless belt 4 is usually a metal roll or a metal endless belt, but in some cases, a resin coating such as a fluororesin may be used. The surface roughness of the metal roll or metal endless belt is 0.5 μm or less, preferably 0.3 μm.
The following are preferred: By setting the surface roughness to 0.5 μm or less, the surface of the cast roll 3 and / or the metal endless belt 4 becomes a mirror surface state, and transparency and surface smoothness of the sheet can be obtained. In addition, the cast roll 3,
The surface of the metal roll 5 for pinching the endless belt 4 may be covered with heat-resistant silicone rubber or elastic elastomer. The hardness of the elastomer used is 55
~ 85 degrees is suitable. The sheet 9 clamped by the arc-shaped clamping portion 8 is immediately cooled by the cooling medium in the secondary cooling step (C) of rapidly cooling by the cooling medium. The cooling medium is not particularly limited, but it is convenient to use water. In the case of water, the temperature of the cooling medium is 50 ° C or lower, preferably 25 ° C or lower. Further, after the secondary cooling step of rapidly cooling with the cooling medium (C), the sheet is guided to the annealing step (D) if necessary. Curling of the sheet can be corrected in the annealing step, and the rigidity of the sheet can be improved because the crystallization of the polypropylene resin has not progressed sufficiently. The annealing process may be a heated oven or a heated metal roll. The heating temperature is -40 of the heat distortion temperature of the polypropylene resin used.
C., preferably -30.degree. C. to heat distortion temperature + 15.degree. C., more preferably + 5.degree. Heat distortion temperature-4
If the temperature is lower than 0 ° C, the effect of correcting the curl and improving the rigidity is small, and if the temperature is higher than the heat deformation temperature + 15 ° C, the sheet is in a softened state and the appearance such as transparency and gloss is deteriorated. The sheet that has been subjected to the (D) annealing step is wound into a product in the (E) winding step. Also, in some cases,
The sheet that has been subjected to the (D) annealing step is cut into desired dimensions in the (F) cutting step, placed on a stacker or the like, and shipped as a product.

Although the forming speed (sheet take-up speed) of the sheet forming apparatus used in the present invention is not particularly limited, since it is the belt forming method, the speed can be significantly increased as compared with the conventional speed.
It is preferably 3 to 30 m / min.

The sheet obtained through these steps is
(A) Thickness of 0.05 to 2.0 mm, (b) transparency (clarity) of 65% or more, (c) transparency (haze) of 1
5% or less, (d) bending stiffness of 7500 to 25000K
It is important to satisfy the property of gf / cm ² . That is, the sheet thickness is (a) in the range of 0.05 to 2.0 mm, (b) the transparency (clarity) is 65% or more,
The sheet of the present invention satisfying the properties of (c) transparency (haze) of 15% or less and (d) bending stiffness of 7500 to 25000 Kgf / cm ² is very superior to the sheet by the conventional method. I have. The thickness of the sheet is 0.05 to 2 mm, preferably 0.07 to 1.8 m
m, more preferably 0.1 to 1.5 mm. If the thickness of the sheet is less than 0.05 mm, it becomes a film, and the function as a sheet cannot be exhibited. Further, if the thickness of the sheet exceeds 2.0 mm, the sheet becomes thick, and the desired transparency of the sheet may not be improved, or the advantage of speeding up may be diminished. Further, the feature of the sheet of the present invention is that it has excellent optical properties, and the transparency (clarity) is 65% or more, preferably 70% or more, more preferably 80% or more. The transparency (haze) is 15% or less, preferably 10% or less, and more preferably 7% or less. The sheet of the present invention is characterized by its mechanical properties, particularly that the sheet is hard and elastic, and has a bending stiffness of 7500 to 25000K.
gf / cm ² , preferably 10,000 to 22000 kg
It is in the range of f / cm ² . The sheet of the present invention has good scratch resistance, and is not scratched even if the surface of the sheet is rubbed with cloth, paper or the like. Furthermore, even in a harsh situation where the sheets rub against each other, the surface of the sheets is unlikely to be scratched. The sheet having the optical characteristics and the mechanical characteristics and further the scratch resistance is obtained for the first time by the composition and the sheet manufacturing process defined in the present invention.

Another feature of the sheet of the present invention is the above (C).
In the secondary cooling step of rapidly cooling with a cooling medium, (e) the skin layer has a thickness of 20% or less, and (f) the core layer structure is formed into a fine crystal structure, thereby maintaining transparency,
It is possible to obtain a sheet having excellent mechanical strength. That is, in FIG. 2, a film-like molten resin 2 extruded from a T-die 1 is subjected to an arc-shaped clamping pressure between a cast roll 3 having a mirror finish and an endless belt 4 formed in an arc shape along the roll. A pressure is applied between the portions 8 to form a skin layer having a smooth surface on both surfaces of the film-shaped molten resin 2. The thickness of each skin layer is preferably 20% or less of the total sheet thickness, and if it exceeds 20%, the transparency of the sheet may decrease. On the other hand, the core layer of the sheet is rapidly cooled with the cooling medium (C) in a state where the core layer is not completely cooled and solidified in the arc-shaped pressing portion and in the vicinity of the exit of the arc-shaped pressing portion, so that the core layer has a fine crystal structure.
Such a fine crystal structure is characterized by the absence of spherulites that impair transparency. When a polypropylene resin other than the composition used in the present invention, for example, a nucleating agent-free polypropylene resin is used, this core layer has a spherulite of about 10 μm if it is large and not a fine crystal structure, resulting in poor transparency of the sheet. There is a fear. The skin layer and core layer of the sheet can be observed with a polarizing optical microscope at about 200 times. Also, the fine crystal structure or spherulites of the core layer is 3500 with an electron microscope.
It can be observed at about twice.

[0019]

EXAMPLES The present invention will be described below with reference to examples and comparative examples, but the present invention is not limited thereto. Examples 1 to 13 and Comparative Examples 1 to 6 Polypropylene-based resin sheets or polyethylene-based resin sheets were manufactured using the apparatus shown in FIG. The polypropylene resin composition and sheet production conditions used are as shown in Tables 1 to 5, respectively. The sheet forming apparatus specifications are as follows. [Sheet molding device specifications] Extruder screw: diameter = 90 mm, L / D = 36 T die: surface length = 1250 mm, die lip = 1 to 3
mm Metal endless belt: SUS, thickness 0.8 mm, surface roughness 0.3 mμ Cast roll: surface roughness 0.3 mμ Cooling medium quenching process: water tank (length 4 m, temperature 15
C.) Annealing process: Metal roll (100.degree. C.) Tables 1 to 5 show the physical properties of the sheet obtained under the above conditions.
It was shown to. The physical properties used in the present invention are based on the following test methods and measurement methods. [Test Method and Measurement Method] Melt Flow Rate: According to JIS K 6758, 230 ° C., 2.16 Kg Load Transparency (Clarity): Sheet Permeation by Clarity Meter TM-1D Model of Murakami Color Research Laboratory Co., Ltd. Light Measurement Transparency (Haze): ASTM D 1003-61
Conformity Bending stiffness: Conforms to JIS K 7106 Heat deformation temperature: Conforms to JIS K 7207 Softening temperature: Conforms to JIS K 6758 Scratch resistance: Friction tester type II for dye fastness test
Suga Tester Co., Ltd. (JIS L 0823 compliant), friction element 200 g / 300 times, scratch resistance judgment ◎: good (no scratches, no surface change) ○: good (no scratches) Δ: bad (some scratches) X: Poor (severe scratches)

Comparative Examples 7 to 8 Sheets were formed by an ordinary air knife method without using the metal endless belt method sheet forming apparatus shown in FIG. That is, the film-like resin extruded in a molten state from the T die was caused to follow an arc shape on a roll of the same type as the cast roll used in the above example, and air was blown from the opposite side of the cast roll. Table 6 shows the polypropylene resin component used and the physical properties of the obtained sheet.

[0021]

[Table 1]

[0022]

[Table 2]

[0023]

[Table 3]

[0024]

[Table 4]

[0025]

[Table 5]

[0026]

[Table 6]

[0027]

In the present invention, by using a specific polypropylene resin composition and a specific sheet molding method,
Even with a thick sheet, a sheet having remarkably excellent optical properties (transparency, glossiness), appearance properties (surface smoothness), scratch resistance and mechanical properties can be obtained. Further, even with a thick sheet, a sheet having excellent optical properties, scratch resistance and mechanical properties at high speed can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic view of a manufacturing process for manufacturing a sheet of the present invention.

FIG. 2 is an enlarged view of a first cooling process of the metal endless belt method sheet manufacturing apparatus.

[Explanation of symbols]

1: T die, 2: molten resin, 3: cast roll, 4:
Endless belt, 5, 6, 7: roll, 8: arcuate pressing portion,
9: Sheet.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location C08K 5/49 C08L 23/10 KFL // B29K 23:00

Claims (12)

[Claims] (1) 0.01 to 0.5 parts by weight of a phosphorus-based antioxidant and / or a phenol-based antioxidant of 0.1 to 100 parts by weight of a resin component containing a polypropylene polymer as a main component. 01-0.5 parts by weight, (2) 0.01-0.5 parts by weight of glycerin fatty acid ester and / or 0.01-0.5 parts by weight of fatty acid amide, and a scratch-resistant polypropylene system obtained from the composition. Resin sheet. 2. The scratch resistance according to claim 1, wherein the composition further contains (3) 0.02 to 1.0 part by weight of a nucleating agent with respect to 100 parts by weight of the resin component. Adhesive polypropylene resin sheet. The polypropylene resin sheet has the following (a) to (d): (a) a thickness of 0.05 to 2.0 mm, (b) a transparency (clarity) of 65% or more, (c) ) Transparency (haze) is 15% or less, (d) Bending stiffness is 7500 to 25000 Kgf / cm.
^2. The scratch-resistant polypropylene-based resin sheet according to claim 1 or 2, which satisfies the property of. The polypropylene-based polymer is selected from a propylene homopolymer, a propylene-ethylene random copolymer or a mixed composition thereof in an amount of 100 to 50% by weight, and a polyethylene-based polymer up to 50% by weight. At least one type of claim 1,
The polypropylene resin sheet having scratch resistance according to item 2 or 3. The polypropylene-based polymer comprises 95 to 70% by weight of a propylene homopolymer and 5 to 30% by weight of a propylene-ethylene random copolymer.
A polypropylene resin sheet having scratch resistance as described in. 6. The scratch-resistant polypropylene-based resin sheet according to claim 1, 2, 3, 4, or 5, wherein the glycerin fatty acid ester is stearic acid monoglyceride. 7. The nucleating agent is at least one selected from talc, an organic carboxylic acid or a metal salt thereof, an organic phosphate metal salt, and a sorbitol compound. The polypropylene resin sheet having scratch resistance according to 3, 4, 5 or 6. (10) 0.01 to 0.5 parts by weight of a phosphorus-based antioxidant and / or a phenol-based antioxidant of 0.1 to 100 parts by weight of a resin component containing a polypropylene-based polymer as a main component. 01-0.5 parts by weight, (2) 0.01-0.5 parts by weight of glycerin fatty acid ester and / or 0.01-0.5 parts by weight of fatty acid amide, (3) nucleating agent 0.02-1. At least (A) a film-shaped molten resin is extruded from a T die, and (B) the film-shaped molten resin is formed into an arc shape along a cast roll and the roll using a composition containing 0 part by weight. A sheet obtained by pinching with an endless belt, the sheet comprising:
(D): (a) thickness of 0.05 to 2.0 mm, (b) transparency (clarity) of 65% or more, (c) transparency (haze) of 15% or less, (d) bending stiffness of 7500. ~ 25,000 Kgf / cm
^{2. A} method for producing a scratch-resistant polypropylene resin sheet, characterized by satisfying the properties of. 9. The polypropylene-based polymer is selected from a propylene homopolymer, a propylene-ethylene random copolymer or a mixed composition thereof in an amount of 100 to 50% by weight and a polyethylene-based polymer up to 50% by weight. It is at least 1 sort (s), The manufacturing method of the scratch resistance polypropylene resin sheet of Claim 8 characterized by the above-mentioned. 10. The polypropylene-based polymer comprises propylene homopolymer of 95 to 70% by weight and propylene-ethylene random copolymer of 5 to 30% by weight.
A polypropylene resin sheet having scratch resistance as described in. 11. The method for producing a scratch-resistant polypropylene resin sheet according to claim 8, 9 or 10, wherein the glycerin fatty acid ester is stearic acid monoglyceride. 12. The nucleating agent is at least one selected from talc, organic carboxylic acids or metal salts thereof, organic phosphate metal salts, and sorbitol compounds. The method for producing a scratch-resistant polypropylene resin sheet according to 9, 10, or 11.