JPH0788930A - Method and apparatus for producing thermoplastic resin sheet or film - Google Patents

Abstract

PURPOSE:To produce a thermoplastic resin sheet or film made excellent in appearance characteristics such as glossiness or surface smoothness regardless of thickness by forcibly cooling the rear surface of the metal endless belt wound around the peripheral surface of a casting drum to the temp. range from the thermal deformation temp. of a thermoplastic resin to the softening temp. thereof by a fluid. CONSTITUTION:The film like thermoplastic resin 2 extruded from a T-die 1 in a molten state is cooled while pressed between a casting drum 3 and the corrosion-resistant endless metal belt 4 fitted over at least three metal rolls having horizontal axial lines and having flexibility imparted thereto under definite tension in a circular arc shape to be formed into a sheet. The rear surface of the metal endless belt 4 wound around the peripheral surface of the casting drum 3 is forcibly cooled to the temp. range from the thermal deformation temp. of a thermoplastic resin to the softening temp. thereof in the circular arc region coming into contact with the peripheral surface of the casting drum 3 by a fluid.

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 thermoplastic resin sheet or film suitable for packaging foods, stationery such as files, various packaging cases, various industrial applications and the like.

[0002]

2. Description of the Related Art Air knife method and polishing roller method are known as methods for producing the thermoplastic resin sheet or film.

[0003]

In the former air knife method, since a sheet or film is manufactured by press-bonding a film-like molten resin onto a cast drum with air pressure blown from a nozzle, fluctuations in the thickness of the sheet surface to which air is blown However, the smoothness cannot be maintained, and one side of the sheet or film is cooled by air, so rapid cooling cannot be performed. As a result, there is a drawback that a sheet or film excellent in surface smoothness and thickness accuracy cannot be formed. The upper limit of the pressure force of this air is about 3000 mm of water column, and since there is only one point of pressure contact with air, the production speed of a sheet or film of commercial value is about 20 m / min. Therefore, the air knife method is mainly used for producing a thin sheet or film having a thickness of about 0.2 to 0.5 mm, which does not require the appearance characteristics of the sheet or film.
It is not suitable for producing thick sheets having a thickness of about 0.7 mm or more. The latter polishing roller method is a method in which a sheet of molten resin is sandwiched between a pair of metal rollers to produce a sheet, but the contact between the pair of rollers completes the shaping of the sheet thickness and surface texture at the same time. When the take-up speed is as low as about 4 m / min or less, a sheet with excellent surface smoothness can be obtained, but when the take-up speed is about 6 m / min or more, the shaping of the sheet cannot be followed and a sheet with commercial value is obtained. I will not be able to. In addition, since a wavy wave is generated in a thin sheet having a thickness of about 0.4 mm or less, it becomes impossible to produce a sheet having a commercial value. The object of the present invention is to solve the above-mentioned problems of the prior art, to cool the front and back surfaces of the sheet or film almost equally, and to provide a thermoplastic resin sheet having excellent appearance characteristics such as gloss and surface smoothness regardless of its thickness. Alternatively, it is to provide a method and an apparatus for manufacturing a film at high speed to the market.

[0004]

In order to solve the above-mentioned problems, the specified invention is a film-shaped thermoplastic resin extruded in a molten state from a T-die on a cast drum and a metal roller having at least three horizontal axes. The endless belt, which is entangled with a certain amount of tension and has flexibility to impart corrosion resistance, cools it into a sheet shape while pressing it in an arc shape while cooling it into a sheet shape. A method for producing a thermoplastic resin sheet or film, characterized in that a fluid is applied to the back surface of the metal endless belt wound around the peripheral surface, and the thermoplastic resin sheet or film is forcibly cooled within a temperature range of a softening temperature from a heat deformation temperature of the thermoplastic resin. .

In order to solve the above problems, two metal rollers are arranged at a position in the vicinity of the cast drum in the above manufacturing method at intervals in the circumferential direction, and at least T
The peripheral surface of the metal roller near the die is coated with heat-resistant rubber or elastomer having elasticity, the cast drum is pressed against the metal endless belt with the coated metal roller, and then the metal is placed between these two metal rollers. While cooling the thermoplastic resin with the endless belt and the cast drum under pressure, the back surface of the metal endless belt wound around the cast drum peripheral surface is made of a thermoplastic resin with a fluid in an arc region in contact with the cast drum peripheral surface. It is characterized in that the thermoplastic resin is formed into a sheet by forcibly cooling it within a temperature range from the heat distortion temperature to the softening temperature.

In order to solve the above-mentioned problems, the invention of this apparatus is such that, on the downstream side of the extrusion nozzle of the T-die, there is a cast drum which receives the thermoplastic resin extruded from this nozzle in its gap, and a cast drum which is located above this cast drum. One metal roller is arranged as a pair, and the first metal roller is equipped so as to be able to approach and separate from the cast drum, and the downstream side from the approach point of the cast drum and the first metal roller. There is a second metal roller that is in contact with the peripheral surface of the cast drum, and a metal endless belt is engaged between these two metal rollers and a third metal roller under a certain tension. In the area between the first and second metal rollers, the metal endless belt has flexibility to run along the peripheral surface of the cast drum, and this running area Is a fluid-type forced cooling device for blowing and cooling a fluid on the back surface of the metal endless belt wound around the circumference of the cast drum, and the first for pressing the metal endless belt on the cast drum. The surface of the metal roller is covered with a heat-resistant rubber or an elastomer having elasticity, which is an apparatus for producing a thermoplastic resin sheet or film.

In order to solve the above problems, the forced cooling device in the thermoplastic resin sheet or film manufacturing device is provided with a fluid temperature adjusting device connected to the secondary side of the blower and wound around the cast drum peripheral surface. A cooling casing that forms a fluid chamber chamber having an opening that opens toward the back surface of the metal endless belt, that connects the fluid temperature adjusting device and the cooling casing, and supplies the fluid whose temperature is adjusted by the fluid temperature adjusting device. It is preferably composed of a fluid supply pipe for supplying into the cooling housing. In order to solve the problem, the cooling housing in the thermoplastic resin sheet or film manufacturing apparatus is connected to the primary side of the blower through its suction port, and the fluid is forcibly circulated. Is desirable. In order to solve the above problems, it is preferable that the fluid sprayed from the fluid type forced cooling device in the thermoplastic resin sheet or film manufacturing apparatus is air, mist or liquid. In order to solve the above problems, the cast drum in the apparatus for manufacturing the thermoplastic resin sheet or the film has a structure that is heated from the inside, and the surface roughness is preferably 0.5 μm or less. In order to solve the problems, it is preferable that the metal endless belt in the thermoplastic resin sheet or film manufacturing apparatus is made of SUS, carbon steel or a titanium alloy.

The polypropylene resin, which is one of the crystalline thermoplastic resins used in the present invention, is a crystalline propylene homopolymer or a copolymer of propylene with one or more comonomers other than propylene, such as ethylene and butene. Crystalline copolymers and mixtures thereof are used. These polypropylene resins include antioxidants, lubricants, antistatic agents, slip agents, anti-blocking agents, UV absorbers, nucleating agents, transparency improvers, organic peroxides, pigments, inorganic materials such as talc and calcium carbonate. In some cases, a system filler, an organic filler such as wood powder or synthetic fiber, another resin or rubber such as polyethylene or ethylene propylene rubber may be appropriately added and used. Further, other thermoplastic resins include polyethylene, polystyrene, and AB.
S, polyethylene terephthalate, polybutylene terephthalate, polyamide, polycarbonate, vinyl chloride or the like can be used. The sheet or film manufacturing method and apparatus described above are also applicable to the manufacturing of multilayer sheets or laminated sheets. If necessary, the sheet or film thus produced is directly introduced into a water tank for secondary cooling, and then the cooling liquid adhering to the surface of the sheet is removed, and then the thermal deformation of the thermoplastic resin using this sheet is carried out. Temperature-40
When the heat treatment is carried out in the temperature range of from 0 ° C to the heat distortion temperature + 15 ° C, the transparency of the crystalline thermoplastic resin sheet or film is particularly enhanced. If necessary, directly guide the sheet or film thus produced to the water tank for secondary cooling,
When removing the cooling liquid adhering to the surface of the sheet and then heat treating the thermoplastic resin using this sheet in a temperature range of −40 ° C. to + 15 ° C.
The transparency of the crystalline thermoplastic resin is increased.

[0009]

EXAMPLES Next, typical examples of the apparatus invention described in claims 3 to 8 will be described below. In FIG. 1, reference numeral 1 denotes a T-die. On the downstream side of the extrusion nozzle of the T-die 1, there is a cast drum 3 for receiving a molten polypropylene resin 2 extruded from the nozzle in its gap and a first die located above the cast drum 3. The first metal roller 15 is arranged as a pair, and the first metal roller 15 is in contact with the peripheral surface of the cast drum 3 at the downstream side in the rotation direction of the cast drum 3 from the approach point between the cast drum 3 and the first metal roller 5. Two metal rollers 6 are arranged, and the metal endless belt 4 is engaged between the two metal rollers 5 and 6 and the third metal roller 7, and between the first and second metal rollers 5 and 6. In the area, the metal endless belt 4 has flexibility to run along the peripheral surface of the cast drum 3, and in the running area, the metal endless belt 4 is provided.
Fluid type forced cooling device A that cools by spraying fluid on the back of
Has been placed. The surface of the first metal roller 5 for pressing the metal endless belt 4 on the cast drum 3 is coated with heat-resistant silicone rubber or elastic elastomer. The coating thickness is 5 to 15 mm, and the rubber hardness of the elastomer used is 55 to 85 degrees. The cast drum 3 is structured such that it is heated from inside by heating oil or the like, and its surface roughness is 0.5 μm.
m or less, preferably 0.3 μm or less. The metal endless belt 4 is made of SUS, a kind of carbon steel or titanium alloy, and SUS is preferable from the viewpoint of corrosion resistance.

The surface roughness of the metal endless belt 4 in contact with the molten resin is 0.5 μm or less, preferably 0.
This metal endless belt 4 is preferably 3 μm or less.
Is used as a belt by welding a thin metal plate, it is necessary to prevent the unevenness of the weld joint from affecting the sheet. When the thickness of the metal endless belt 4 is thin, unevenness is likely to occur in the connecting portion, and when it is thick, the flexibility of the metal endless belt 4 is lost and use is hindered. Therefore, the thickness of the metal endless belt is 0.5 to 1.2 mm. The degree is appropriate. The forced cooling device A has an air temperature adjusting device 11 connected to the secondary side of the blower 10 and an air opening 12 opening toward the back surface of the metal endless belt 4 wound around the circumference of the cast drum 3. Cooling housing 14 forming chamber chamber 13, air temperature adjusting device 11 and cooling housing 14
And an air supply pipe 15 for supplying the air whose temperature is adjusted by the air temperature adjusting device 11 into the cooling housing 14. The front and rear walls 1 connected to the cooling housing 14 are provided on the carrying-in and carrying-out end surfaces of the cooling housing 14 with respect to the metal endless belt 4.
4a, 14b (see FIG. 4) may be provided, but in some cases, the front and rear walls are also used by the outer peripheral surfaces of the two front and rear metal rollers 5 and 6. The cooling housing 14 is connected to the primary side of the blower 10 through its suction port 16 so that the air is forcibly circulated (see FIG. 5). The fluid sprayed from the fluid type forced cooling device A may be a mist or a liquid in addition to the air.

Next, the operation of the apparatus of the embodiment will be described with reference to representative embodiments of the manufacturing method according to the invention of claims 1 and 2. First, the state in which the first metal roller 5 is brought close to the peripheral surface of the cast drum 3 is set, and the film-shaped polypropylene resin, which is a kind of thermoplastic rigid ground cast extruded from the T die 1 in a molten state, is set. 2 is supplied between the metal endless belt 4 engaged with the first metal roller 5 and the cast drum 3, and then the cast drum 3 and the first and second metal rollers 5, 6 and the metal endless belt. Four
Is guided to the arc-shaped pressing portion 8 formed by the cast drum 3 and the metal endless belt 4. At this time, the variation in the molding thickness of the film-shaped polypropylene resin 2 is absorbed by the silicone rubber or elastomer coated on the first metal roller 5. Further, the cast drum 3 and the first and second
Metal endless belt 4 hooked between the metal rollers 5 and 6 of
The gap between the pressing portions 8 formed in 1 can be mechanically adjusted by vertical displacement of the cast drum 3 or the like (not shown). The thickness of the product sheet or film 9 is finally set by setting the gap size of the pressing portion 8.
At this time, the metal endless belt 4 is also heated from the inside by the first and third metal rollers 5 and 7 which are heated from the inside by heating oil or the like, and the cast drum 3 is also heated from the inside, preferably at 50 to 150 ° C. There is.

Next, the temperature of the primary cooling sheet 9 sent out from the arcuate pressing portion 8 is (the test method is JIS K-
6758, the load is set to 1 kgf, and the same applies to the following temperature range). If the temperature is lower than the heat deformation temperature, a sheet having excellent transparency and gloss cannot be obtained, and if the temperature is higher than the softening temperature, the sheet is too soft and peelability from the cast drum 3 or the metal endless belt 4 is deteriorated. However, fine scratches may frequently occur on the surface of the sheet, or wrinkles may occur in the sheet in the step of introducing the sheet into a water tank (not shown), so that a good sheet may not be formed. At this time, the back surface of the metal endless belt 4 in the arcuate pressing portion 8 is forcibly cooled to a temperature range from the heat deformation temperature of the polypropylene resin to the softening temperature by the fluid type fluid type forced cooling device A.

If necessary, the first metal roller 5'is completely separated from the cast drum 3, and the film-shaped polypropylene resin 2 is guided to the pressing portion 8 to change the thickness. In some cases, the endless metal belt in the pressing portion 8 absorbs it due to its flexibility (see FIG. 2). In this case, the first metal roller 5'has a peripheral surface made of rubber,
It may not be covered with an elastic elastomer.

[0014]

According to the manufacturing method of the invention described in claim 1, the molten resin extruded on the cast drum is cooled from both the front and back surfaces almost equally, and the glossiness of the front and back surfaces,
A thermoplastic resin sheet or film having excellent appearance characteristics such as surface smoothness can be obtained. Further, the product sheet or film can be manufactured with high quality from thin to thick, and the production speed can be increased to several times that of the conventional method.
Therefore, the sheet or film obtained by the production method of the present invention is for packaging such as food packaging and pharmaceutical packaging,
Cases for stationery, packaging such as cosmetics and household items,
Suitable for industrial materials. In the method invention described in claim 2, in addition to the above effects, the heat-resistant rubber or the elastomer having elasticity of the peripheral surface of the first metal roller sufficiently absorbs the variation in the thickness of the sheet or film, Thickness accuracy can be improved. According to the apparatus invention described in claim 3, the manufacturing method according to any one of claims 1 and 2 can be implemented, and equivalent effects can be obtained. In the apparatus invention described in claim 4, in addition to the effect of the invention described in claim 3, the metal endless belt can be simply and appropriately forcibly cooled by the temperature-controlled cooling air. According to the apparatus invention described in claim 5, in addition to the effect of the invention described in claim 4, the metal endless belt is provided without forcibly circulating the fluid and disturbing the external environment of the manufacturing apparatus, particularly the temperature and the air flow. Can be forcibly cooled. According to the apparatus invention described in claim 6,
The same effect as that of the invention described in claim 3 can be obtained. According to the apparatus invention described in claim 7, in addition to the effect of the invention described in claim 3, the transferability of the thermoplastic resin sheet or film can be enhanced, and the surface smoothness of the sheet or film can be enhanced. In the apparatus invention described in claim 8, in addition to the effects of the invention described in claims 3 to 7, the corrosion resistance of the metal endless belt can be enhanced.

An experimental example will be described below. Experimental Example 1 A polypropylene resin sheet was manufactured using the apparatus shown in FIG. At this time, the polypropyrin resin used was Chisso Polypro XF1893 (manufactured by Chisso Corporation) having a density of 0.90 g / m ³ and a melt flow rate of 1.8 g / 10 min. The resin temperature is 240 ℃
T-die extruder (extruder cylinder diameter 100m
m, L / D = 36, die width 550 mm, die lip interval 1.2 mm). The extruded molten resin was passed through the apparatus shown in FIG. 1 to obtain a polypropylene resin sheet having a thickness of 0.3 mm.

The sheet manufacturing conditions are as follows. Metal endless belt made of SUS, thickness 0.8mm, width 600mm, surface roughness 0.3μm, the cooling temperature by the fluid forced cooling device in the arcuate pressure portion is set to 90 ° C. Cast drum width 650 mm, surface roughness 0.3 μm, temperature 90 ° C.
Set the first metal roller to a surface of 10 mm thick silicone rubber with a rubber hardness of 65 degrees.
Coating Arc-shaped clamping part Length 60 cm, spacing 0.3 mm Sheet take-up speed Cast drum and metal endless belt are set to the same speed of 5 m / min The polypropylene resin sheet thus obtained is
It had excellent gloss and surface smoothness, and had no streaks, wrinkles, or waviness, and had excellent appearance characteristics.

Experimental Example 2 A polypropylene resin sheet having a thickness of 1.0 mm was manufactured under the same manufacturing conditions as in Experimental Example 1 except that the sheet take-up speed was 10 m / min. This sheet was also excellent in various characteristics similar to those of Experimental Example 1, that is, excellent in gloss and surface smoothness, and free of streaks, wrinkles, and waviness, and thus excellent in appearance characteristics.

Experimental Example 3 A polypropylene resin sheet having a thickness of 0.3 mm was manufactured under the same manufacturing conditions as in Experimental Example 1 except that the sheet take-up speed was 20 m / min. This sheet was also excellent in various properties similar to those in Experimental Example 1, that is, excellent in gloss and surface smoothness, and free from streaks, wrinkles, corrugations, and the like, and excellent in appearance properties.

Experimental Example 4 A polypropylene sheet having a thickness of 0.3 mm was produced under the same production conditions as in Experimental Example 1 except that the sheet take-up speed was 40 m / min. This sheet also has excellent gloss and surface smoothness.
Since it had no streaks, wrinkles, or waviness, it had excellent appearance characteristics.

Experimental Example 5 Using the apparatus shown in FIG. 2, the same T-die extrusion apparatus as in Experimental Example 1 was used, and the thickness was 1.0 m under the same manufacturing conditions.
m polypropylene resin sheet was produced. At this time, the first metal roller is separated from the peripheral surface of the cast drum, and the peripheral surface of the first metal roller is not covered with the silicone rubber. Therefore, in the arcuate pressing portion other than the second metal roller, the molten resin is held only by the peripheral surface of the cast drum and the metal endless belt, and is pressed by the tension applied to the metal endless belt and the restoring force of the metal endless belt. To be done. In this case, the length of the arcuate pressing portion is set to 40 cm. The sheet thus obtained had excellent gloss and surface smoothness, was free of streaks, wrinkles, and waviness, and had good appearance characteristics.

Experimental Example 6 Using the apparatus shown in FIG. 2 as in Experimental Example 5, a polypropylene resin sheet having a thickness of 0.3 mm was manufactured under the same manufacturing conditions as in Experimental Example 4. The sheet thus obtained was also excellent in surface smoothness, free of streaks, wrinkles, and wavy, and had good appearance characteristics.

Comparative Example 1 The first metal roller 5 was used without using the metal endless belt of FIG.
The air knife is arranged at the position of No. 2, and the same resin as in Experimental Example 1 is used, and the sheet pulling speed is 10 m / min.
A 3 mm polypropylene resin sheet was produced. The gloss and surface smoothness of this sheet were slightly poor, and vertical wrinkles were generated.

Comparative Example 2 The same resin as used in Experimental Example 1 was used in a T-die extruding apparatus (extruder cylinder diameter 100 mm, L / D = 36, T-die width 600).
mm, die lip spacing 1.5 mm)
Extruded at 40 ° C., the extruded molten resin was subjected to a polishing roller temperature of 80 ° C., and a polypropylene resin sheet having a thickness of 0.3 mm was manufactured at a sheet take-up speed of 5 m / min. This sheet had good gloss and surface smoothness, but wavy. The characteristic values used in the experimental examples and comparative examples were measured by the following test methods. Melt flow rate: JIS K-6758 (23
0 ° C, load 2.16 kgf) Density: JIS K-6758 Surface smoothness, gloss: Visual observation Streaks, wrinkles, corrugations: Visual observation

[Brief description of drawings]

FIG. 1 is an explanatory view showing one embodiment of an apparatus for carrying out the method of the present invention.

FIG. 2 is an explanatory diagram showing another aspect.

FIG. 3 is a cross-sectional view showing a temperature gradient of molten resin in the arcuate pressing portion in FIG.

FIG. 4 is a schematic vertical cross-sectional view showing a mode in which front and rear walls connected to the cooling housing 14 are provided on the carry-in and carry-out end surfaces of the cooling housing with respect to the metal endless belt 4.

5 is a schematic vertical cross-sectional view showing a suction port portion of the cooling housing in FIG.

[Explanation of symbols]

 1 T Die 2 Membrane Polypropylene Resin 3 Cast Drum 4 Metal Endless Belt 5 First Metal Roller 6, 7 Second and Third Metal Roller 8 Arc-Shaped Nipple 9 Product Sheet or Film A Fluid Forced Cooling Device

Claims (8)

[Claims] 1. A film-shaped thermoplastic resin extruded in a molten state from a T-die is engaged with a cast drum and a metal roller whose at least three axes are horizontal, and a certain tension is applied to impart corrosion resistance to corrosion. With a flexible metal endless belt, it cools into a sheet shape while pressing it in an arc shape,
In the arc area that contacts the peripheral surface of this cast drum,
A method for producing a thermoplastic resin sheet or film, characterized in that the back surface of the metal endless belt wound around the peripheral surface of a cast drum is fluidly cooled to a temperature range of a softening temperature from a heat deformation temperature of the thermoplastic resin. . 2. At least two metal rollers are disposed in the vicinity of the cast drum at intervals in the circumferential direction, and at least the metal roller peripheral surface near the T-die is made of heat-resistant rubber or elastic elastomer. A metal endless belt is coated on the cast drum with the coated metal roller, and then the thermoplastic resin is pressure cooled between the two metal rollers by the metal endless belt and the cast drum. In the circular arc area in contact with the peripheral surface of the drum, the back surface of the metal endless belt wound around the peripheral surface of the cast drum is forcibly cooled with a fluid within a temperature range from the heat deformation temperature of the thermoplastic resin to the softening temperature. 2. The method for producing a sheet or film according to claim 1, wherein the sheet is in the form of a sheet. 3. A casting drum, which receives the thermoplastic resin extruded from this nozzle in its gap, and a first metal roller located above this casting drum, are arranged as a pair on the downstream side of the extrusion nozzle of the T die. Yes, this first
The metal roller of the cast drum is provided so as to be able to move toward and away from the cast drum, and the metal roller of the cast drum and the peripheral surface of the cast drum face downstream from the approach point of the cast drum and the first metal roller in the rotation direction of the cast drum. A second metal roller which is in contact with the second metal roller is arranged, and an endless metal belt is engaged between the two metal rollers and a third metal roller under a certain tension. In the area between, the metal endless belt has the flexibility to run along the peripheral surface of the cast drum, and in this running area, on the back surface of the metal endless belt wound around the peripheral surface of the cast drum. A fluid type forced cooling device for blowing and cooling a fluid is arranged, and the surface of the first metal roller for pressing the metal endless belt on the cast drum is heat-resistant. The thermoplastic resin sheet or film production apparatus is characterized in that are coated with an elastomer having rubber or elastic. 4. A fluid chamber having a fluid temperature adjusting device connected to a secondary side of a blower and an opening opening toward a back surface of the metal endless belt wound around a cast drum peripheral surface. A cooling housing that forms a chamber, and a fluid supply pipe that connects the fluid temperature adjusting device and the cooling housing and supplies a fluid whose temperature is adjusted by the fluid temperature adjusting device into the cooling housing. The apparatus for producing a thermoplastic resin sheet or film according to claim 3. 5. The thermoplastic resin sheet according to claim 4, wherein the cooling housing is connected to the primary side of the blower through its suction port, and the fluid is forcedly circulated. Film manufacturing equipment. 6. The apparatus for producing a thermoplastic resin sheet or film according to claim 3, wherein the fluid sprayed from the fluid type forced cooling device is air, mist or liquid. 7. The crystalline thermoplastic resin sheet or film according to claim 3, wherein the cast drum is structured to be heated from the inside and has a surface roughness of 0.5 μm or less. Manufacturing equipment. 8. The apparatus for producing a thermoplastic resin sheet or film according to claim 3, 4, 5, 6, or 7, wherein the metal endless belt is made of SUS, carbon steel or a titanium alloy.