JPH10278097A - Manufacture of polypropylene sheet and device for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the manufacturing method of a highly lustrous and highly transparent polypropylene sheet as well as a device therefor. SOLUTION: One surface of the polypropylene sheet 12 of molten condition, which is containing nucleating agent, is cooled by a first roll 13 while the other surface of the same is heated by a heating device 16 to the (thermal deformation temperature -10 deg.C)-(melting point +100 deg.C) of the polypropylene sheet 12 and, thereafter, the heated surface of the sheet 12 is cooled by a second roll 15. The surfaces of the first and second rolls 13, 15, which are contacted with the polypropylene sheet 12, are provided with a mirror surface having the surface roughness of 0.5 μm or less in the surface roughness Ra.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for producing a highly glossy and highly transparent polypropylene sheet.

[0002]

2. Description of the Related Art As shown in FIG. 2, when a conventional polypropylene sheet is manufactured,
The polypropylene sheet 23 in a molten state extruded from the die 22 of the extruder 21 is cooled on one surface side of the sheet 23 by the first cooling roll 24, and then the sheet 23 is cooled by the second cooling roll 25. Is cooled on the other side. According to such a manufacturing method, on one side of the polypropylene sheet 23, the mirror transfer and the cooling of the polypropylene sheet 23 in the molten state are simultaneously performed by the first cooling roll 24. Good gloss.

However, when the other side of the sheet 23 comes into contact with the second cooling roll 25, it comes into contact with the first cooling roll 24 and the temperature of the sheet 23 drops. Good mirror surface transfer is not performed. As a result, depending on the thickness and the take-up speed of the polypropylene sheet 23, it was difficult to impart the same high gloss to both sides of the sheet 23.

[0004] Production apparatuses have been proposed to solve the above problem by making a cooling roll for cooling the other side of the polypropylene sheet movable (Japanese Utility Model Publication No. 60-23138, Japanese Utility Model Publication No. No. 60-23139, JP-A-8-
No. 230018, etc.). However, according to these manufacturing apparatuses, the mechanism is complicated and the cost of the apparatus is expensive.

Accordingly, an object of the present invention is to provide a method for producing a highly glossy and highly transparent polypropylene sheet and an apparatus therefor.

[0006]

According to a first aspect of the present invention, there is provided a method of manufacturing a polypropylene sheet, wherein one surface of a nucleating agent-containing polypropylene sheet in a molten state is cooled by a first cooling means. The other surface of the polypropylene sheet is (heat distortion temperature -10 ° C) to (melting point +100).
° C), and then heat the heated side of the sheet to a second
It is characterized by cooling by cooling means.

The polypropylene may be a homopolymer or a random copolymer. The molten polypropylene sheet is, for example, a polypropylene sheet immediately after being extruded from a die of an extruder. The heating of the polypropylene sheet may be either direct heating in which the heating means is brought into contact with the sheet or indirect heating in which the heating means is not brought into contact with the sheet, but direct heating is more efficient.

If the heating temperature of the polypropylene sheet is lower than (heat distortion temperature -10 ° C.), the transfer of the surface of the cooling means to the sheet becomes insufficient because the sheet is not sufficiently softened. On the other hand, when the heating temperature is higher than (melting point + 100 ° C.), the sheet may be excessively softened and the sheet may hang down from the cooling roll. The heating of the other surface of the polypropylene sheet may be simultaneous with the cooling of the one surface or may be slightly delayed in time. The sheet includes a film having a relatively different thickness only.

As the nucleating agent, an organic substance and an inorganic substance having a nucleating effect of increasing the crystallization rate can be arbitrarily used. Specific examples of the organic nucleating agent include, for example, dibenzylidene sorbitol compounds and phosphate compounds. The dibenzylidene sorbitol compounds include dibenzylidene sorbitol (abbreviated as DBS), para-methyl-DBS, para-ethyl-DBS, para-chlor.
DBS, etc. are included. This DBS-based compound is particularly effective for improving transparency.

The above-mentioned phosphate compounds include sodium bis (4-t-butylphenyl) phosphate, phosphoric acid-2,
Sodium 2'-methylenebis (4,6-di-t-butylphenyl), and the like. Other nucleating agents include aluminum dibenzoate, basic di-para-tertiary
Butyl aluminum benzoate, beta-sodium naphthoate, sodium caproate, 2,2'-methylenebis (4,6-ditert-butylphenyl) phosphate
Phthalocyanines, quinacridones, high melting point polymers, and the like can also be used.

Specific examples of the inorganic nucleating agent are, for example, alum, titanium and talc. The content of the nucleating agent is, for example, 0.02 to 1.0 part by weight based on 100 parts by weight of the polypropylene base material.

An apparatus for manufacturing a polypropylene sheet according to a second invention of the present invention comprises a first cooling means for cooling one surface of a polypropylene sheet in a molten state, and a heating means for heating the other surface of the polypropylene sheet. And a second cooling means for cooling the other heated surface of the sheet.

The structure of the cooling means is optional. For example, the cooling means may be a roll and a cooling medium may be passed inside. The heating means may be either a direct heating means or an indirect heating means. As the indirect heating means, a halogen heater, an infrared heater, a hot air blower, a gas heater, or the like can be used.

The apparatus for manufacturing a polypropylene sheet according to a third aspect of the present invention is the apparatus for manufacturing a polypropylene sheet according to the second aspect, wherein
Is characterized in that the surface in contact with the polypropylene sheet has a mirror surface having a surface roughness Ra (center line average roughness) of 0.5 μm or less. The surface roughness Ra is 0.5
If it exceeds μm, the surface state of the roll is transferred as it is, so that the degree of gloss and transparency of the obtained polypropylene sheet decreases.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method and an apparatus for producing a polypropylene sheet according to an embodiment of the present invention will be described with reference to FIG. The manufacturing apparatus of this embodiment includes an extruder 11, a first cooling roll 13 for cooling a molten polypropylene sheet 12, a pressing roll 14 for pressing the molten polypropylene sheet 12 against the first cooling roll 13, A second cooling roll 15 provided so as to be in contact with the first cooling roll 13 via the molten polypropylene sheet 12, and a heating device 16 arranged near the outer peripheral surface of the first cooling roll 13 are provided. It is configured.

A die 17 is attached to a tip of the extruder 11. The second cooling roll 15 is provided on the side facing the pressing roll 14 with the first cooling roll 13 interposed therebetween. The outer peripheral surfaces of the first and second cooling rolls 13 and 15 and the pressing roll 14 are mirror surfaces having a surface roughness Ra of 0.5 μm or less. The heating device 16 includes a halogen heater or the like, and is provided on the surface of the first cooling roll 13 with which the polypropylene sheet 12 contacts.

Using this manufacturing apparatus, a polypropylene sheet 12 is manufactured as follows. First, the die 17 of the extruder 11
Then, polypropylene containing a nucleating agent is extruded into a sheet shape, and the molten sheet 12 is brought into contact with the outer peripheral surface of the first cooling roll 13 by the pressing roll 14. By the first cooling roll 13, the sheet 12 in the molten state is rapidly cooled while one surface on the side of the first cooling roll 13 is subjected to mirror surface transfer.

The heating device 16 simultaneously heats the surface of the sheet 12 on the side of the pressing roll 14 while performing mirror transfer and cooling on one surface. The heating temperature for the back of this sheet 12 is
(Heat deformation temperature −10 ° C.) to (melting point + 100 ° C.). Subsequently, the sheet 12 is moved along the outer peripheral surface of the second cooling roll 15 to perform mirror transfer and cooling on the surface of the polypropylene sheet 12 heated to the above temperature.

[0019]

【Example】

[Examples 1 to 4] In the above embodiment, the polypropylene sheet 12 was manufactured under the following specific conditions of the apparatus and the manufacturing method. Table 1 shows the resins and nucleating agents used in each example. Table 1 also shows the thickness of the sheet 12, the temperature of the sheet surface immediately after external heating by the heating device 16, and the heat deformation temperature of the sheet. Heat deformation temperature of sheet is JIS
It measured according to K7207 (0.46MPa).

Extruder screw: 115 mm in diameter. Die width ... 900mm. Die resin discharge rate: 300kg / hr. Resin temperature at die exit: approx. 255 ° C. Pressing roll diameter ... 350mm. Diameter of the first cooling roll: 600 mm. Diameter of second cooling roll: 350 mm. Linear pressure between the pressing roll and the first cooling roll: 500 N / cm. Linear pressure between the first cooling roll and the second cooling roll: 500 N / c
m. Heating device: halogen heater.

Resin used: Idemitsu Polypro F205S (trade name,
Homopolymer, manufactured by Idemitsu Petrochemical Co., Ltd., MI: 2).
Idemitsu Polypro F534N-4 (trade name, manufactured by Idemitsu Petrochemical Co., Ltd., random copolymer, MI: 6). Nucleating agent: Gelol MD (trade name, manufactured by Shin Nippon Rika Co., Ltd., 1,3-P-methylbenzylidene-2A-P-methylbenzylidene sorbitol). NA-21 (trade name, manufactured by Asahi Denka Kogyo Co., Ltd., main component: bis (2,4,8,10-tetra-tert-butyl-oxo-12H-dibenzo [d, g] [1,3,2] Dioxaphosphin-6-oxide) aluminum hydroxide salt).

Comparative Examples 1 to 3 The same apparatus as in the above example was used, but the resins used, the nucleating agent, the temperature of the sheet surface immediately after external heating, and the like were varied as shown in Table 1.

[Measurement of Properties] The gloss and total haze of the polypropylene sheets obtained in the above Examples and Comparative Examples were measured. Table 1 shows the results. The gloss and total haze were measured according to JIS K 7105.

[0024]

[Table 1]

According to Tables 1 to 4, according to Examples 1 to 4, one surface of the molten nucleating agent-containing polypropylene sheet 12 is cooled by the first cooling roll 13 having a mirror surface, and the heating device 16 is cooled. Then, the other surface is heated to the (heat distortion temperature −10 ° C.) to (melting point + 100 ° C.) of the polypropylene sheet 12, and then the heated surface of the sheet 12 is cooled by the second cooling roll 15 having a mirror surface. And polypropylene sheet 12
The resulting polypropylene sheet 12 is
It can be seen that mirror transfer was performed on both the first cooling roll surface side and the back surface side, and the gloss was good. Further, it can be seen that the total haze is low and the transparency is good.

On the other hand, according to Comparative Example 1, since the polypropylene sheet does not contain a nucleating agent, it can be seen that the gloss and transparency of the obtained polypropylene sheet are poor. According to Comparative Example 2, the heating temperature of the polypropylene sheet by the heating device was lower than (thermal deformation temperature −10 ° C.), and the mirror surface transfer on the pressing roll surface side was not performed. Was poor in gloss. According to Comparative Example 3, since the heating temperature of the polypropylene sheet by the heating device was higher than (melting point + 100 ° C.), the sheet could not be manufactured due to folding wrinkles due to sagging of the sheet.

[0027]

According to the present invention, a highly glossy and highly transparent polypropylene sheet can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic view of an apparatus for manufacturing a polypropylene sheet according to an embodiment of the present invention.

FIG. 2 is a schematic view of an apparatus for manufacturing a polypropylene sheet according to a conventional example.

[Explanation of symbols]

 12 Polypropylene sheet 13 First cooling roll 15 Second cooling roll 16 Heating device 17 Die

Claims (3)

[Claims] 1. A nucleating agent-containing polypropylene sheet in a molten state, one surface of which is cooled by a first cooling means, and the other surface of which is (heat deformation temperature −10 ° C.) to (melting point) of the polypropylene sheet. + 100 ° C.), and thereafter cooling the heated surface of the sheet by a second cooling means. 2. A first cooling means for cooling one surface of a polypropylene sheet in a molten state, a heating means for heating the other surface of the polypropylene sheet, and cooling the other heated surface of the polypropylene sheet. An apparatus for producing a polypropylene sheet, comprising: a second cooling means. 3. The apparatus for manufacturing a polypropylene sheet according to claim 2, wherein the first and second cooling means have a surface in contact with the polypropylene sheet having a surface roughness Ra of 0.1.
An apparatus for producing a polypropylene sheet, having a mirror surface of 5 μm or less.