JP2002273780A - Cooling method for thermoplastic resin film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermoplastic resin film having a high transparency, or a thermoplastic resin extrusion-expanded sheet which has a high independent air bubble coefficient, being 80% or higher, is excellent in plane smoothness, and has a high gloss. SOLUTION: A resin is melt-extruded from a T-die 2 into a film-form. The film 3 is forcibly introduced to the surface of a cylindrical cooling roll 4, which is set at a location being 5 to 150 mm away directly under the T-die and is rotating, by jetting air from an air feeding nozzle 30. Then, the film which is melt-extruded accompanying the rotation of the cylindrical cooling roll 4 is directly cooled to a temperature which is lower than the softening point of a thermoplastic resin of the film material with a cooling water existing in a cooling water channel 57. In this case, the cooling water channel 57 is formed of the cylindrical cooling roll and a water cooling drum 5 having a recess. The recess corresponds with the cylindrical section having an area of approximate l/4 to l/2 of the area of the cylindrical outer peripheral surface of the cylindrical cooling roll. The cooling water is fed to such a cooling water channel 57, and the sheet of the molten film on the cylindrical cooling roll is directly cooled. At the same time, in the extrusion-molding method of the resin film, the sheet is pinched with the cylindrical cooling roll and the water cooling drum.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for melting a crystalline thermoplastic resin such as high-pressure low-density polyethylene, linear linear low-density polyethylene, polypropylene, polymethylpentene-1, polyamide, polycarbonate, polyethylene terephthalate, etc. from an extruder. The present invention relates to a film cooling method for producing a transparent film by kneading, melting and extruding a film from a T-die, and cooling this. This method of cooling a thermoplastic resin film is also useful as a sheet cooling method for producing a foam sheet by extrusion molding from a thermoplastic resin composition containing a foaming agent.

[0002]

2. Description of the Related Art The above-mentioned crystalline thermoplastic resin T-die film has excellent haze (JIS P-8138) of 2 to 6% and is excellent in transparency, so that it can be used for packaging films of fruits and vegetables, shirts, cigarettes and the like, or paper. And as a laminate film on aluminum substrates. These T-die films are prepared by melting and kneading a crystalline thermoplastic resin from an extruder, extruding the film from a T-die into a film, and guiding the film to a cooling roll immediately below the T-die. Spraying cooling air or cooling mist with an air knife near the point of contact and producing the molten film by quenching it, or by quenching the molten film extruded from the T-die into a water tank with a guide roll to produce it. I have.

[0003] The reason why the molten film is rapidly cooled is that, in the process of forming crystals from a molten state of the crystalline thermoplastic resin, rapid cooling has a smaller crystal size than slow cooling, and a more transparent film can be obtained. . However, in the conventional method of forming a T-die film having a thickness of 8 to 100 μm, only a transparent film having a haze of 3 to 6% is obtained with a polypropylene film, and the haze (JIS P-8138) is obtained by further stretching. A stretched film of 5 to 3% is obtained. Low-density polyethylene and linear linear low-density polyethylene have even worse transparency and haze of 3 to 10%
Only a transparent film of a degree can be obtained.

Further, a molten mixture of the expandable polypropylene resin composition is extruded from a T-die into a sheet at atmospheric pressure, guided between two forming rolls adjacent to the lip of the T-die, cooled, and cooled. It is known to produce an open-cell foam sheet of 0.3 g / cm ³ (Japanese Patent Publication No. 5-11).
No. 745). Since the open-cell foam sheet has low strength, it is unsuitable for vacuum forming the sheet into a tray. Polypropylene is a crystalline resin, and has a very low melt viscosity at a temperature higher than the glass transition point compared to an amorphous resin used as a material for trays.
Unable to hold foamed bubbles, easy to break,
It is easy to become open cells.

On the other hand, a molten mixture of the expandable polypropylene resin composition is extruded into a sheet from a T-die lip having an opening of 5 to 30 degrees under atmospheric pressure, and 5 mm from the T-die lip.
Guided between two cooling rolls provided at a position of about 50 mm apart, cooled, and then completely cooled by a plurality of pairs of cooling rolls provided thereafter to obtain closed cells having a density of about 0.3 g / cm ³ . It is also known to produce a mold foam sheet (JP-A-8-142517).

In this method, since the surface of the cooling roll that cools the foamed sheet in contact with the foamed sheet is on a dotted line,
It is necessary to use a plurality of pairs of cooling rolls, and since there is a distance between each cooling roll, in the initial cooling stage, the foaming agent pressure in the sheet overcomes the strength of the skin layer on the sheet surface and foams. Since the foamed sheet is cooled by a cooling roll, the obtained foamed sheet is likely to have wrinkles on its surface, and has a drawback of poor appearance.

Japanese Patent Application Laid-Open No. 7-276472 discloses a method in which a polypropylene resin containing a foaming agent is melt-extruded into a sheet shape through a T-die attached to the tip of an extruder using an apparatus shown in FIG. Roll forming and immersion in water are performed before bubble cracks occur on the sheet surface to obtain a foaming ratio of about 3 times excellent in surface smoothness (density 0.3 g / c
m ³ ) A method for producing a polypropylene resin sheet having closed cells before and after is proposed. However, since the sheet in contact with the roll immediately below the T-die is straight and not a surface, the sheet surface is not sufficiently cooled. Therefore, the sheet is cooled with water in a water tank under atmospheric pressure. When the application is to be applied to the production of a foamed sheet having a high foaming ratio of 5 to 30 times, the outer skin layer is destroyed, traces of re-foaming remain, low gloss, poor appearance and low strength simultaneous cell extrusion. Only foam sheets can be obtained. Alternatively, the sheet is wrapped around the roll directly below and does not become a product.

[0008]

The first object of the present invention is to provide a transparent thermoplastic resin film having a haze of 1 to 3% and excellent transparency by a direct T-die film forming method without adding a stretching step. An object of the present invention is to provide a method for cooling a film that can be manufactured. A second object of the present invention is to provide a sheet cooling method which is excellent in smoothness and glossiness when extruding a closed cell type thermoplastic resin foam sheet. In the following description, the film and the sheet may be collectively referred to as a film.

[0009]

The first aspect of the present invention provides a T
-The thermoplastic resin film melt-extruded from the die is guided to the surface of the cylindrical cooling roll rotating by forcing means, and then the thermoplastic resin film is rotated with the cylindrical cooling roll as the cylindrical cooling roll rotates. Approximately 1/4 to 1/2 of the area of the cylindrical outer peripheral surface of the cylindrical cooling roll
And supplying the cooling water to a cooling water passage formed by a water cooling drum having a concave portion corresponding to the cylindrical portion having an area of the area.The molten film on the cylindrical cooling roll is directly cooled by the cooling water existing in the cooling water passage. An object of the present invention is to provide a method for cooling a thermoplastic resin film, which comprises cooling the film to a temperature lower than the softening point of the thermoplastic resin of the film material.

The thermoplastic resin film melt-extruded from the T-die by the forcing means provided in the gap between the T-die and the cylindrical cooling roll is guided onto the cooling roll immediately below the T-die, and cooled. Since it is rapidly cooled by the cooling water on the roll and the concave surface of the water-cooled drum, a crystalline thermoplastic resin film having extremely excellent transparency can be obtained. Further, at the time of forming the foamed film, the skin layer can be formed on the film surface by blowing the cooling air without taking a long die land of the T-die, so that the foamed film can be easily sent to the water-cooled drum.

According to a second aspect of the present invention, in the method for cooling a thermoplastic resin film, the water cooling drum is a fixed type, and a cooling water path is formed by a concave surface of the water cooling drum and an outer peripheral surface of the cooling roll. Forms a water passage below the concave surface substrate of the water cooling drum, and a drainage passage above the concave surface substrate of the water cooling drum, and is directed to a position in the horizontal direction of the diameter of the cooling roll and intersecting with the water cooling drum. The width of the cooling water passage from below is once narrowed and widened on the upper side after passing through the crossing position, and a bypass passage leading to the drainage passage is provided in the middle of the water passage, and a drainage passage at the bypass passage outlet is provided. A cooling water retaining portion is formed in the drainage portion to be connected.

By providing a water passage for supplying cooling water below the concave surface substrate of the water cooling drum and a drainage passage for discharging cooling water above, the fluctuation width of the temperature of the water cooling drum is reduced, and cooling spots are formed. A film with good appearance which does not appear on the film is obtained. In addition, by providing the water cooling drum base material with the bypass path connecting the water passage and the drain passage, bubbling occurs in the cooling water film formed by the cooling water passage formed by the cooling roll and the concave surface of the water cooling drum. A film which is suppressed and has good appearance without air spots is obtained.

According to a third aspect of the present invention, in the method for cooling a thermoplastic resin film, the water cooling drum includes a storage tank, a cooling water supply mechanism, a replenishment mechanism, and a mechanism for keeping the amount of cooling water in the storage tank constant. The cooling water discharged from the discharge passage of the drum is once returned to the storage tank, supplied from the storage tank to the water passage by the pump, and the cooling water is supplied from the external tank into the storage tank by the pump. Features.

By keeping the amount of cooling water constant, the amount of cooling water supplied to the concave surface of the water cooling drum can be kept uniform.

According to a fourth aspect of the present invention, in the method for cooling a thermoplastic resin film, the forcing means includes: a) an air supply nozzle or an air knife for blowing cooling air onto the surface of the thermoplastic resin film; A pressure reducer for drawing the film toward the cylindrical cooling roll; c) a guide roll provided near the cooling water discharge port of the water cooling drum and near the upper portion of the cylindrical cooling roll. D) The above a, b, and c Or a combination of two or more of the above.

The resin film melt-extruded from the T-die is blown to the surface with cooling air from a nozzle or an air knife, and then rapidly cooled by a cooling roll and water cooling, so that a transparent film can be obtained. Also,
In the case of a foamable resin film, a skin layer is formed on the film surface on the side that comes into contact with the cooling water by the blowing cooling air, so that it is not necessary to increase the land length of the die.

By sucking the melt-extruded film by the decompressor, the film is more quickly attracted to the cylindrical cooling roll side, so that the effect of quenching by the cylindrical cooling roll can be exhibited more.

Further, the rotation of the cylindrical cooling roll and the rotation of the guide roll make the thermoplastic resin film adhere to the cylindrical cooling roll more firmly and increase the speed of discharging the cooling water.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail with reference to the drawings. 1 is a flow sheet diagram showing a process of manufacturing a film, FIG. 2 is a partially enlarged view of a T-die and a cooling roll, FIG. 3 is a perspective view of a water cooling drum, and FIG. 4 shows a bypass of the cooling roll and the water cooling drum. FIG. 5 is a flow sheet diagram showing a process of manufacturing a foam sheet,
FIG. 6 is a partial cross-sectional view showing another embodiment of the bypass of the cooling roll and the water cooling drum.

1 and 5, 1 is an extruder, 2 is T
-Die, 3 is a resin film, 4 is a cylindrical cooling roll, 5
Is a water-cooled drum, 6 and 6 are corona discharge treatment devices, 7 is a draining roll, 8, 8, and 8 are guide rolls, 9 is a winder, 9
0 is a guillotine cutter, 10 is a cooling water storage tank, 11 is a load cell, 12 is a cooling water amount control device, 13 is a cooling water supply pipe,
14 is a pump, 15 is a cooling water discharge pipe, 16 is a cooling water filling tank, 17 is a supply pipe, 18 is a pump, 19, 20, and 2.
1, 22, 23 are communication cables, 24 is a heat exchanger, 25
Is a temperature sensor, 26 is a stirrer, 30 is an air nozzle, 4
0 is a pressure reducer.

The water-cooled drum 5 is of a fixed type, and as shown in FIG. 4, the front face 51 facing the cooling roll 4 has an area of approximately １ ／ to の of the area of the cylindrical outer peripheral surface of the cylindrical cooling roll. The cooling water passage 57 is formed by the concave surface of the water cooling drum and the outer peripheral surface of the cooling roll 4. A water passage 52 for supplying cooling water to the concave surface of the water-cooled drum is formed in the water-cooled drum substrate 50 below the concave surface of the water-cooled drum in order to supply the cooling water to the cooling water channel 57, and a cooling passage is provided above the concave surface. A drain passage 53 for discharging water is formed in the water-cooled drum substrate 50, and the water passage 52 and the drain passage 53 are connected by a bypass passage 54.

Reference numerals 55 and 56 denote doctor blades, and the tips 55a and 56a are located at positions separated from the outer peripheral surface of the cooling roll by substantially the film thickness. The doctor blade is
At the start of the test operation (5 to 30 minutes) of the film production machine, after the molten film is guided to the cooling roll 4, it is fitted to a water-cooled drum, and then the cooling water is supplied to the water-cooled drum 5 from a storage tank 10 by a pump 14 by a pump 14. Through the water passage 52. The upper doctor blade 56 may be replaced with a guide roll 56 'as shown in FIG. Guide roll 5
Numeral 6 'is disposed near the cooling water discharge port, near the upper portion of the cylindrical cooling roll, and is rotatable, and rotates in a direction opposite to the rotation direction of the cylindrical roll. The non-standard product obtained during the test operation is removed as burrs, and only a regular product is wound around the film winder 9 as in the conventional film manufacturing technique.

The water-cooled drum 5 and the concave surface of the cooling roll 4
The width of the cooling water passage 57 formed between the cooling water passage 57 and the outer peripheral surface is once narrowed from below in the horizontal direction M of the cooling roll 4 by the bypass passage forming member 54a, and becomes wider on the upper side after passing through the position M. An upper portion of the bypass passage forming member 54a, which is notched on a side close to the cooling roll, forms a cooling water retaining portion 57b.
The presence of the bypass passage 54 prevents bubbling (air bubbles) in the cooling water in the cooling water passage 57. The generated turbulence is rectified. The width of the bypass passage 54 is larger than the width of the cooling passage at the M position of the cooling passage 57 formed by the cooling roll 4 and the water cooling drum 5 (see FIG. 4).

The water-cooled drum 5 includes a storage tank 10, cooling water supply mechanisms 13 and 14, cooling water replenishment mechanisms 15 and 18, and mechanisms 11, 12, 19, 20, and 2 for maintaining a constant amount of cooling water in the storage tank.
The cooling water discharged from the discharge passage of the water-cooled drum is once returned to the storage tank, supplied from the storage tank 10 to the water passage by the pump 14 through the pipe 15, and when the cooling water is insufficient, the external tank 15 Further, the cooling water is supplied to the storage tank 10 by the pump 18. That is, in the water passage 52, the pump 14 is operated from the storage tank 10 to supply the supply pipe 1.
The cooling water is supplied through 3 and the cooling water discharged from the drain 53 is returned to the storage tank 10 through the drain pipe 15. Storage tank 1
Load cell 1 always keeps the amount of cooling water in 0 constant.
1, the weight is measured, and the amount of water is
2 and the control device instructs the operating speeds of the pumps 14 and 18 from the cables 19 and 21 so that the cooling water amount in the storage tank becomes constant. When the amount of cooling water in the storage tank 10 is insufficient, the pump 18 operates to fill the storage tank 10 with cooling water from the tank 15.

The temperature of the cooling water in the storage tank 10 is measured by the temperature sensor 25 so that the temperature of the cooling water supplied to the water cooling drum is also kept constant, and the control device 1
The control device 12 transmits a heating or cooling instruction to the heat exchanger 24 via the cable 23. The temperature of the cooling drum 5 is lower than the softening point of the crystalline thermoplastic resin, preferably 20 to 140 ° C. lower than the softening point of an olefin resin such as polyethylene, polypropylene and polymethylpentene-1 (water cooling drum 5). The temperature and supply amount of cooling water to be supplied are adjusted so that the temperature of the water-cooled drum 5 becomes 100 to 140 ° C. for polyethylene terephthalate and nylon 6. The softening point means a temperature _Tim at which melting starts in a differential thermal scanning curve (DSC curve) shown in FIG. 8 obtained by differential thermal analysis specified in JIS K-7121. When the resin is a mixture and more than one _Tim is present, this means the temperature of the lower _Tim .

The temperature of the cooling roll 4 is desirably close to the temperature of the water-cooled drum. When the temperatures are different, the temperature difference between the two is preferably within 10 ° C. The cooling medium of the cooling roll 4 includes tap water, well water, ethylene glycol (5 to 5).
30% by weight) water, surfactant (0.1-1% by weight)
Water, ethylene glycol and the like are used.

As the cooling water supplied to the water cooling drum,
Pure water (distilled water), ion-exchanged water, water containing ethylene glycol (5 to 30% by weight), water containing a surfactant (0.1 to 1% by weight), water containing isopropyl alcohol (1 to 3% by weight), etc. Can be used. When the film is used for food packaging, it is desirable that impurities in the cooling water do not adhere to the film surface. Therefore, distilled water containing no impurities is optimal.

The gap distance of the cooling water passage 57 formed by the cooling roll 4 and the concave portion of the water cooling drum 5 is equal to the film thickness plus 10 to 5 at the horizontal position M of the diameter of the narrowest cooling roll.
000 μm, preferably the desired film thickness plus 50 to 3,000 μm.

In order to keep the amount of cooling water constant, a liquid level gauge may be used instead of using the load cell 11.
The temperature of the cooling medium is preferably from -10 to + 60C.

As shown in FIG. 2, an air nozzle 30 as a forcing means is provided below the T-die 2, and an air outlet is located near a lip which is a film extrusion port. The air of the cooling medium may include mist. Surface 1 m ² per resin film, sprayed is cooled Eya blows so that the amount of 0.1~1.5m ^3. Further, an air knife may be used in place of the air nozzle, or a holding roll 56 'as shown in FIG. The air blown out from the nozzle or the air knife suppresses the extruded resin film to the cylindrical cooling roll 4 side.

The decompressor 40 is provided on the back surface opposite to the front surface of the thermoplastic resin film to which the cooling air is blown, and the decompressor is used to reduce the pressure from −10 mmH ₂ O to −150 mmH ₂ O.
By reducing the pressure to a certain degree, the thermoplastic resin film is attracted to the cylindrical cooling roll 4 side.

When the target resin film is a foamed sheet, a thermoplastic resin containing a foaming agent is melted and extruded from the T-die into a sheet, and the thermoplastic resin containing the foaming agent is placed under the T-die 5 to 150.
mm to the surface of a rotating cylindrical cooling roll installed at a position distant from the cylindrical cooling roll by rotating the cylindrical cooling roll. Approximately 1 area of the outer peripheral surface
Cooling water is supplied to a cooling water passage formed by a water cooling drum having a concave portion corresponding to a cylindrical portion having an area of ４ to し て, and a molten sheet on a cylindrical cooling roll is directly present in the cooling water passage. The cooling water is used to cool the sheet to a temperature lower than the softening point of the resin of the sheet material, and the sheet is sandwiched between the cylindrical cooling roll and a water-cooled drum. Immediately after the sheet is extruded from the T-die, a cooling medium may be sprayed on the sheet surface to cool the sheet.

Next, the guillotine cutter 9 is used as the foam sheet.
0, where they are made into rectangular or square sheets of appropriate dimensions and width, and sequentially laminated. If the guillotine is not cut, it is wound on a winder.

The gap distance of the cooling water passage 57 formed by the cooling roll 4 and the concave portion of the water cooling drum 5 is determined in consideration of the thickness of the foamable resin sheet 3 melt-extruded from the T-die and the desired expansion ratio. If the thickness of the extruded foamable resin sheet is t (unit: mm) and a foaming sheet having a P-fold expansion ratio is to be obtained, the gap distance = txP (mm) at the diameter horizontal position M of the narrowest cooling roll. ). For example, in order to obtain a foamed resin sheet having a thickness of 0.5 mm and a density of 0.10 g / cm ³ (expansion ratio of about 9), the diameter of the narrowest cooling roll is measured in the horizontal direction. The gap distance at the position M is 4.5 mm. Assuming that the radius of the cooling roll 4 is r, the radius R of the concave portion of the water cooling drum 5 is 1.
The design is made in consideration of the expansion ratio so as to be from 01r to 1.2r.

The raw material thermoplastic resin includes propylene homopolymer, propylene / ethylene block copolymer,
Propylene / ethylene / butene-1 block copolymer,
Propylene-ethylene random copolymer, propylene
Ethylene-butene-1 random copolymer, propylene
Methylpentene-1 random copolymer, propylene / hexene-1 block copolymer, propylene / pentene
1-butene-1 block copolymer, polyethylene, linear polyethylene, nylon 6, polycarbonate and the like. Melt flow rate of thermoplastic resin according to JIS K-7210 standard is adjusted for air bubbles, sheet strength,
0.5 to 10 g / 10 min, preferably 0.8 to 5 g / 10 min, from the viewpoint of extrusion characteristics.

The thermoplastic resins may be used alone or in combination of two or more. Further, additives such as a nucleating agent, a heat stabilizer and a weathering agent may be added to the resin in an amount of 0.3 to 2% by weight.

As the blowing agent, azodicarbonamide,
Dinitrosopentamethylenetetramine, sodium bicarbonate,
Sodium hydrogen carbonate, toluenesulfonyl hydrazide,
Thermal decomposition type chemical blowing agents such as p, p'-oxybisbenzenesulfonyl hydrazide: propane, butane, pentane,
Olefin-based physical blowing agents such as hexane and cyclopentane: gaseous or liquid at room temperature such as freon-based physical blowing agents such as monochloro-1,1-difluoromethane, 1-chloro-1,1-difluoroethane, and trichlorotrifluoroethane Physical foaming agent: Inorganic gas such as air, carbon dioxide gas, and nitrogen gas can be used.

For low foam sheets, a thermal decomposition type chemical foaming agent is preferable, and for high foam sheets, a physical foaming agent is preferable. Among them, for low foam sheets, a mixture of sodium bicarbonate and citric acid or a soda salt thereof, which is commercially available from Boehringer Ingelheim, Germany under the trade name of Hydrocerol, is suitable for obtaining fine bubbles. For highly foamed sheets, freon-based physical foaming agents are preferred, followed by propane and butane. The thermal decomposition type chemical blowing agent is used in an amount of 1 to 5% by weight of the resin, and the physical blowing agent is used in an amount of 8 to 30% by weight of the resin.

The T-die has a flat lip shape,
As disclosed in Japanese Patent Application Laid-Open No. 8-142157, an opening of 5 to 30 degrees may be widened at the tip of the lip. For a highly foamed sheet, a gear (gear) pump is preferably provided between the screw of the extruder and the T-die.

The foamed thermoplastic resin sheet produced in this manner has a closed cell content of 65% or more, preferably 80% or more.
As described above, the density is 0.03-0.3 g / cm ³ , and the thickness is 0.1-
10 mm, preferably 0.3-5 mm, bubble diameter 20-1
It is a non-crosslinked resin foam sheet having a smooth surface of 000 μm, preferably 150 to 400 μm.

[0041]

EXAMPLE 1 Using the film production machine shown in FIGS. 1, 2 and 4, using distilled water as cooling water, thickness 40 μm, haze 1.0%
Was produced.

That is, as the resin material of each layer, propylene is 67%, melting peak temperature T _{pm is} 164 ° C., melting end temperature T _{em is} 174 ° C., softening point T _{im is} 152 ° C., and melt flow rate is 10 g / 10 min. A mixture of 100 parts by weight of a homopolymer, 0.3 parts by weight of 2,6-di-tert-butylcresol as a heat stabilizer, 0.4 parts by weight of RA1010 (registered trademark) and 0.3 parts by weight of Mark II (registered trademark) As a resin for a surface layer, 100 parts by weight of a propylene homopolymer as the intermediate layer at a melt flow rate of 10 g / 10 min, 0.3 parts by weight of 2,6-di-tert-butylcresol as a heat stabilizer, RA1010 (registered trademark) ) 0.4 parts by weight and 0.3 parts by weight of Mark II®, mono-, di-glyceride stearic acid 1.0 as antistatic agent
A part by weight of the mixture was used as a resin for the back layer to have a crystallinity of 67
%, The melting peak temperature _T pm 152 ° C., the melting end temperature T
_em 165 ° C., softening point T _im 139 ° C., melt flow rate 8.0 g / 10 min, 100 parts by weight of propylene / ethylene copolymer, 0.3 part by weight of 2,6-di-tert-butylcresol as a heat stabilizer, RA1010 (registered trademark) 0.
A mixture of 4 parts by weight and 0.3 parts by weight of Mark II® was used.

Each of the above resin mixtures is melt-kneaded at 260 ° C. using a separate extruder, extruded at 255 ° C. from a co-extrusion T-die into a film, and supplied to an air supply provided immediately below the co-extrusion T-die. While spraying a cooling air of 25 ° C. from the nozzle onto the film surface in an amount of 0.5 m ³ / m ² , the pressure on the back surface of the film was reduced by −60 mmH ₂ O using a pressure reducer. The molten film is guided on a 900 mm cooling roll (temperature: 35 to 40 ° C., rotation speed: 36 rpm) and the molten film is rotated by the cooling roll to rotate the molten film on a water-cooled drum (temperature: 35 to 40 ° C.). (2000 μm at horizontal position M in diameter) Guide into the recess and cool the film with the pure water film flow in the cooling channel formed by the cooling roll and the recess of the water-cooled drum (The film temperature at the position of the draining roll 7 was 78 ° C.).

Then, the film was guided to a draining roll by rotating a cooling roll, and after removing water on the surface, the film was sent to a corona discharge device by a guide roll (film temperature 55 ° C.), and corona discharge treatment was applied to the front and back surfaces of the film. . After slitting 10cm width at both ends, thickness 40μm
A polypropylene film of (surface layer: 8 μm / intermediate layer: 30 μm / backside layer: 2 μm) was wound around a winder (film temperature: 30 ° C.). Haze degree of this film (JIS P-8
138) was 1.0%.

Example 2 Using a foamed resin sheet manufacturing machine shown in FIGS. 5 and 6, using distilled water as cooling water, a thickness of 2 mm and a density of about 0.1
g / cm ³ of a homopolypropylene foam sheet was produced. That is, the crystallinity is 68%, and the melting peak temperature T _pm 16
4 ° C., the melting end temperature _T em 176 ° C., a softening point _T im 15
100 parts by weight of polypropylene at 4 ° C. and a melt flow rate of 1.2 g / 10 min, 0.3 parts by weight of 2,6-di-tert-butylcresol as a heat stabilizer, 0.4 parts by weight of RA1010 (registered trademark) and Mark II (Registered trademark)
0.3 parts by weight and 2 parts by weight of Hydrocelol (trade name) manufactured by Boehringer Ingelheim GmbH as a foaming agent were melt-kneaded at 210 ° C. using an extruder, and 210 kneaded with a T-die.
Extruded into a sheet having a thickness of 0.2 mm at a temperature of 200 ° C., guided on a cooling roll having a diameter of 900 mm (temperature: 20 to 25 ° C., rotation speed: 36 rpm) 50 mm below the T-die, rotating the cooling roll, and guiding the water cooling drum. By rotating the roll, the molten foamable sheet is cooled with a water-cooled drum (temperature 20 to 25).
° C, the gap distance of the cooling water channel is 2.0 mm at the horizontal position M of the diameter of the narrowest cooling roll). The pure water film flow in the cooling water channel formed by the cooling roll and the concave portion of the water cooling drum is guided into the concave portion. To cool the sheet (the sheet temperature at the position of the draining roll 7 is 80 ° C.).

Then, the sheet is guided to a draining roll by rotating a cooling roll, and after removing water on the surface, the sheet foamed and cooled by a guide roll is sent to a corona discharge device (sheet surface temperature of 55 ° C.). Was subjected to corona discharge treatment. After slitting 10cm width at both ends,
A polypropylene foam sheet having a thickness of about 2 mm was cut to a length of 1200 mm with a guillotine cutter to obtain a rectangular foam sheet, which was sequentially stacked.

This foamed extruded sheet has a closed cell ratio of 88.
%, Bubble diameter 110-190 μm, density 0.098 g / c
m ³ , a highly glossy foam sheet with no wrinkles and excellent surface smoothness.

Example 3 The sheet manufacturing machine shown in FIGS. 5 and 6 (provided with a gear pump between the T-die and the extruder) was foamed with an apparatus provided with the air supply nozzle and the depressurizer shown in FIG. Used as a resin sheet manufacturing machine, using distilled water as cooling water, thickness 3
A propylene / ethylene / butene-1 block copolymer extruded foam sheet having a thickness of 0.06 g / cm ^{3 and} a thickness of 0.06 g / cm ³ was obtained.

That is, the crystallinity was 64% and the melting peak temperature was 1
63 ° C (two peaks outside), melting end temperature 172 ° C,
Softening point 142 ° C, melt flow rate 1.0g / 10
100 parts by weight of a propylene / ethylene (1.2% by weight) / butene-1 (0.5% by weight) block copolymer having a density of 0.902 g / cm ³ and 2,6-di-t as a heat stabilizer
0.4 parts by weight of butyl cresol and Irgafos
(Registered Trademark) 0.6 part by weight is melt-kneaded at 210 ° C. using an extruder, and a nozzle provided in the middle of the extruder is provided with a pump using a pump. And then mixed with the molten resin to form a foamable resin, which is further fed to a gear pump, kneaded at 205 ° C, extruded at 200 ° C from a T-die into a sheet having a thickness of 0.20 mm, and directly below the T-die. A cooling air of 25 ° C. is blown to the sheet surface from an air supply nozzle provided in the above, and the back surface of the sheet is depressurized with a pressure reducer at −60 mmH ₂ O. The temperature is 25-30 ° C., the number of rotations is 30 rpm, and the molten sheet is rotated by the cooling roll, and the molten sheet is cooled with a water-cooled drum (temperature 25-30 ° C .; (The diameter of the cooling roll is 3.0 mm at the horizontal position M in the horizontal direction.) One side of the sheet that has been foamed by the pure water film in the cooling channel formed by the cooling roll and the recess of the water-cooled drum is cooled (sheet surface temperature). 75 ° C).

Then, the foamed sheet was guided to a draining roll by rotating a cooling roll, and after removing water on the surface, the sheet was sent to a slitting machine (not shown) by a guide roll (sheet temperature: 40 ° C.) (both ends were 10 cm). After slitting the width, a polypropylene-based block copolymer foam sheet having a thickness of about 4.5 mm was cut with a guillotine cutter for 120 minutes.
It was cut to a length of 0 mm to obtain a rectangular foam sheet, which was sequentially stacked.

This foamed extruded sheet has a closed cell ratio of 86.
%, Bubble diameter 160-200 μm, density 0.060 g / c
m ³ , a highly glossy foam sheet with no wrinkles and excellent surface smoothness.

Example 4 The sheet manufacturing machine shown in FIGS. 5 and 6 (provided that a gear pump was provided between the T-die and the extruder) was equipped with an air supply nozzle and a decompressor shown in FIG. used as a resin sheet manufacturing apparatus to obtain a thickness 4.5 mm, a density of 0.03 g / cm ³ to propylene-ethylene random copolymer extruded foam sheet using distilled water as the coolant.

That is, a crystallinity of 78% and a melting peak temperature of 1
54 ° C., melting end temperature 171 ° C., softening point 138 ° C., melt flow rate 1.2 g / 10 min, density 0.900 g /
100 parts by weight of a propylene / ethylene (3.8% by weight) random copolymer in cm ³ , 2,6-di-t
0.4 parts by weight of butyl cresol and Irgafos
(Registered trademark) 0.6 parts by weight is melt-kneaded at 210 ° C. using an extruder, and a pump provided to a nozzle provided in the middle of the compression section of the extruder uses a pump to supply butane gas to 22% by weight of resin in the compression section. And then mixed with the molten resin to form a foamable resin, which is further fed to a gear pump, kneaded at 200 ° C., extruded from a T-die at 197 ° C. into a sheet having a thickness of 0.15 mm, and immediately below the T-die. with blown cooling air sheet surface of 25 ° C. than Eya supply nozzle which is installed in the seat back side and decompressed at -60mmH ₂ O in a vacuum vessel, then, the diameter 1200mm which apart 70mm just below T- die cooling roll ( The temperature is 25-30 ° C., the number of rotations is 30 rpm, and the molten sheet is cooled by the rotation of the cooling roll, and the molten sheet is cooled by a water-cooled drum (temperature 25-30 ° C. (The diameter of the cooling roll is 4.5 mm at the horizontal position M in the horizontal direction), and one surface of the sheet foamed by the pure water film in the cooling water passage formed by the cooling roll and the recess of the water-cooled drum is cooled (sheet surface temperature). 70 ° C).

Subsequently, the foamed sheet was guided to a draining roll by rotating a cooling roll, and after removing water on the surface, the sheet was sent to a slitting machine (not shown) by a guide roll (sheet temperature: 40 ° C.), and both ends were 10 cm in length. After slitting the width, a polypropylene-based random copolymer foam sheet having a thickness of about 4.5 mm was subjected to a guillotine cutter for 120 minutes.
It was cut to a length of 0 mm to obtain a rectangular foam sheet, which was sequentially stacked.

This foamed extruded sheet has a closed cell ratio of 80.
%, Bubble diameter 230 to 310 μm, density 0.031 g / c
m ³ , a highly glossy foam sheet with no wrinkles and excellent surface smoothness.

[0056]

According to the method for cooling a thermoplastic resin film of the present invention, a resin film having extremely good transparency or a foamed resin sheet having high gloss can be produced.

[Brief description of the drawings]

FIG. 1 is a flow sheet diagram showing a process of manufacturing a resin film.

FIG. 2 is an enlarged sectional view of a T-die and a cooling roll portion.

FIG. 3 is a perspective view of a water cooling drum.

FIG. 4 is a partial perspective view showing a bypass path between a cooling roll and a water cooling drum.

FIG. 5 is a flow sheet diagram showing a process of manufacturing a foamed resin sheet.

FIG. 6 is a partial cross-sectional view showing another embodiment and showing a bypass path between a cooling roll and a water-cooled drum.

FIG. 7 is a flow sheet diagram showing a process for producing a known foamed resin sheet.

FIG. 8 is a differential thermal scanning curve (DSC) of a thermoplastic resin.

DESCRIPTION OF SYMBOLS 1 Extruder 2 T-die 3 Resin film 4 Cooling roll 5 Water cooling drum 50 Base material 51 Water cooling drum concave front surface 52 Water passage 53 Drain 54 54 Bypass 55 Doctor blade 56 Doctor blade 57 Cooling water 10 Storage tank 13 Supply pipe 15 Drain pipe 30 Air nozzle 40 Pressure reducer 90 Guillotine cutter

Claims (4)

[Claims] 1. A thermoplastic resin film melt-extruded from a T-die is guided to the surface of a rotating cylindrical cooling roll by a forcing means, and then the thermoplastic resin film is rotated as the cylindrical cooling roll rotates. Cooling water is supplied to a cooling water passage formed by the cylindrical cooling roll and a water cooling drum having a concave portion corresponding to a cylindrical portion having an area approximately １ ／ to の of the area of the cylindrical outer peripheral surface of the cylindrical cooling roll. Supplying the molten film directly on the cylindrical cooling roll, and cooling the film to a temperature lower than the softening point of the thermoplastic resin of the film material with the cooling water present in the cooling water passage. A method for cooling a plastic resin film. 2. The water-cooled drum is of a fixed type, and forms a cooling water passage between the water-cooled drum concave surface and the outer periphery of the cooling roll.
The cooling water passage forms a water passage below the concave surface base material of the water cooling drum and a drainage passage above the concave surface base material of the water cooling drum, and crosses the water cooling drum in the horizontal direction of the diameter of the cooling roll. The width of the cooling water channel from below toward the position is once narrowed and widened on the upper side after passing through the intersection,
2. The cooling water retention part is formed in a part of the drainage channel connected to the drainage channel at the outlet of the bypass channel, provided in the middle of the water channel to the drainage channel. 3. The method for cooling a thermoplastic resin film according to item 1. 3. The water cooling drum includes a storage tank, a cooling water supply mechanism, a replenishment mechanism, and a mechanism for maintaining a constant amount of cooling water in the storage tank. The cooling water discharged from the discharge path of the water cooling drum is returned to the storage tank once. 2. A structure in which the storage tank is supplied to a water passage by a pump and cooling water is supplied from an external tank into the storage tank by a pump.
3. The method for cooling a thermoplastic resin film according to item 1. 4. The forcing means includes: a) an air supply nozzle or an air knife for blowing cooling air onto the surface of the thermoplastic resin film; b) a depressurizer for drawing the thermoplastic resin film toward the cylindrical cooling roll; c) a water-cooled drum And d) a guide roll provided near the upper portion of the cylindrical cooling roll at a position near the cooling water discharge port. D) A combination of at least two of the above a, b and c. The method for cooling a thermoplastic resin film according to claim 2, wherein: