JPH09314645A - Manufacture of plasticizer-containing thermoplastic resin sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize the high sped production of a thermoplastic resin sheet containing a plasticizer, by which excellent thickness accuracy, heat shrinkage factor and external appearance are obtained, by a method wherein an oriented sheet is cooled under the condition being pressurized through pinching so as to introduce the obtained sheet in a cooling water tank and finally orient it again. SOLUTION: After being extruded from a mold 1 into a form of a sheet by feeding a composition containing a thermoplastic resin and a plasticizer to an extruder, a shaped matter is oriented with a cold pressing device and pressurized through pinching so as to introduce the resultant cooled sheet in a cooling water tank 4 in order to orient again after being cooled down completely. The draw ratio of the sheet applied during the process ranging from the outlet of the mold 1 to the cooling rolls 2 and 3 provided in the cold pressing device is preferably set to be as large as possible. Because the sheet extruded from the outlet of the mold 1 is in the viscous region under a high temperature molten state, resulting in causing no recovering of the strain developing during orienting under the temperature, which is lower than the temperature of the sheet extruded from the outlet of the mold.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a thermoplastic resin sheet containing a plasticizer.

[0002]

2. Description of the Related Art Japanese Unexamined Patent Publication No. 03-284935 discloses
It has high mechanical strength and excellent adhesion to laminated glass, and extrudes a polyvinyl butyral sheet containing a plasticizer with a refractive index that is almost the same as that of glass from the mold, draws it into a water tank, cools it, and then embosses it with a heating roll and embossing roll. A method for producing a thermoplastic resin sheet used as an intermediate film sandwiched between laminated glasses by transferring is described.

[0003]

However, Japanese Patent Laid-Open Publication No. Hei 3-2
When a polyvinyl butyral sheet is manufactured using the technique described in Japanese Patent No. 84935, the water temperature at each position in the cooling water tank installed immediately after the mold varies, so that the thickness varies when stretched in the water tank. was there.

As a countermeasure against this, two problems arise when the film is not stretched in a water tank and is stretched by a heating roll and an embossing roll in a subsequent process. One of them is that the sheet immediately after entering the water tank is in a molten state (sheet temperature 180 to 200
(° C), the sheet is liable to sag in the water tank and stable conveyance cannot be performed. Second, the sheet temperature rises from 30 to 50 ° C to 100 to 130 ° C from the heating roll to the embossing roll inlet, and it is known from the data of extensional viscosity that the temperature region is in the elastic region. When stretched, the heat shrinkage rate increases.

That is, in the technique disclosed in Japanese Patent Laid-Open No. 3-284935, it is impossible to simultaneously improve the heat shrinkage rate and the thickness accuracy.

Further, when the technique described in JP-A-3-284935 is used, a plasticizer vapor is generated at the time of molding, but the plasticizer vapor stays in the vicinity of the sheet and the mold, and the retained plasticizer vapor. Is condensed at a temperature lower than the molding temperature,
The condensate often drops and adheres to the surface of the molten sheet, and the adhered matter (condensate) is cooled and solidified in the water tank, which deteriorates the appearance of the surface of the sheet, or Since it is soft, there is a problem in that the surface of the sheet is damaged by the fall of the condensate.

An object of the present invention is to solve the above problems and to provide a manufacturing method capable of producing a thermoplastic resin sheet containing a plasticizer having excellent thickness accuracy, heat shrinkage ratio and appearance, at a high speed. And

[0008]

In order to achieve the above object, the present invention is a method for producing a thermoplastic resin sheet containing a plasticizer, wherein a composition containing the thermoplastic resin and the plasticizer is extruded. , After extruding the shaped article obtained by shaping the sheet into a sheet from the mold, after stretching with a cooling press device,
It is characterized in that the sheet obtained by cooling is introduced into a cooling water tank while being pressed so as to narrow the sheet, and the sheet is completely cooled and then stretched again.

As described above, in the present invention, the sheet extruded from the mold is guided to and pressed by the cooling press device before being guided to the water tank, so that the adhesion of the sheet to the cooling device is improved.

Therefore, the sheet floats with respect to the cooling device in front of the water tank, and the plasticizer that volatilizes in the gap is condensed and is cooled and solidified on the surface of the sheet. In addition, since the plasticizer vapor is easily taken into the sheet, the plasticizer vapor remaining in the vicinity of the sheet and the mold, which occurs when the technique of Japanese Patent Laid-Open No. 3-284935 is used, is reduced, and the plasticizer condensate is generated. The appearance problem is less likely to occur.

Moreover, since the cooling efficiency is increased, a high production amount is guaranteed. In addition, the variation in thickness that occurs immediately after leaving the mold is corrected by the pressure of the cooling press device, which ensures excellent thickness accuracy.

In the present invention, the cooling press device is a device having at least two cooling rolls or cooling belts for cooling and pressing the sheet shaped object extruded from the mold, or a cooling roll. And a device that combines a cooling belt. The form of the cooling roll may be any, for example, single-sided roll, cooling press roll, etc.,
The cooling belt may have any form, for example, a single-sided belt,
There are double-sided belts.

Further, in the water tank installed after the cooling press device, a fixed support is provided in order to stably convey the sheet without shaking, but any form may be used and the roll or non-rotation may be used. A support or the like may be used.

Here, as the thermoplastic resin used in the present invention, those which can be combined with a plasticizer are targeted. For example, a butyral resin or vinyl chloride described in JP-A-3-284935. Examples thereof include but are not limited to butyral resins.

The plasticizer used in the present invention is not particularly limited, but if the boiling point is too high, the viscosity becomes high and it becomes difficult to knead, and a sheet having poor dispersibility of the plasticizer is formed,
Further, if the boiling point is too low, the plasticizer vapor escapes from the surface of the sheet and the amount dissolved in the resin becomes small, so that it becomes impossible to obtain a sheet having a desired blending, so that the one having a boiling point near the extrusion temperature is effective. .

As a plasticizer satisfying this requirement, for example, when a butyral resin is used as the thermoplastic resin, triethylene glycol-2-ethyl butyrate, tetraethylene glycol di-2-ethyl butyrate, di- (butyl di resin) is used. Glycol) adipate and the like.

The mold used in the present invention may be any mold as long as it can extrude a composition containing a thermoplastic resin and a plasticizer into a sheet form. For example, a T die or a coat hanger die. A flat die such as is suitable.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A cooling press device installed between a mold and a water tank is a device having two or more cooling rolls or cooling belts, or a device combining a cooling roll and a cooling belt. A cooling press roll, a single-sided roll or the like is used as the cooling roll, and a single-sided belt, a double-sided belt or the like is used as the cooling belt. FIG. 1 is a diagram showing a configuration example of a manufacturing process used for implementing the present invention.
This manufacturing process includes a die such as a T-die, a cooling roll, a water tank, and a take-up machine. After that,
An embodiment of the present invention will be described with reference to FIG. 1 as an example.

It is desirable that the stretching ratio from the die outlet to the cooling roll installed in the cooling press device is set as large as possible within the following constraint conditions. The reason is that the sheet extruded from the die exit is in a viscous region because it is in a high-temperature molten state, and the strain generated by stretching there is not recovered under the sheet temperature extruded from the die exit. . That is, a sheet having a small heat shrinkage ratio in a wide temperature range and having excellent sheet dimensional stability when laminated glass is laminated and fused on both surfaces of the sheet is provided. In the process after the cooling roll, the temperature of the sheet does not become higher than this, so the stretching ratio from the die outlet to the cooling roll is set as large as possible. However, the draw ratio is set by the cooling roll rotation speed ratio.

[Conditions for Manufacturing Equipment] (1) If the gap between the mold lips is small, the charring resin is likely to adhere to the periphery of the mold lip and adhere to the surface of the extruded sheet, causing a problem in appearance. Therefore, it is desirable to set a large gap to some extent. On the other hand, if it is too large, it is necessary to increase the amount of stretching from the die outlet to the cooling roll according to the thickness of the final product, which causes a problem of biteability of the sheet into the cooling roll. From this, when the thickness of the final product is 760 μm, the mold lip gap is 2.0 mm to 5.
It is desirable to set it to 0 mm.

(2) The lower the draw ratio from the cooling roll to the water tank, the more uniform the thickness is.
If it is too low, the sheet fluctuates in the water tank and cannot be conveyed stably, so it is desirable to set it to 1.01 to 1.1 times. (However, when the roll is installed in the water tank)

Considering these constraints, when the thickness of the final product is 760 μm, the draw ratio from the die outlet to the roll of the cooling press machine depends on the die lip gap.
It is desirable to set 0 to 3.5 times.

The pressure of the cooling press device is set to a value that satisfies the following conditions (1) and (2). (1) The pressing force of the upper cooling roll increases the adhesion of the sheet to the lower cooling roll. Therefore, the sheet floats with respect to the lower cooling roll, and plastic problems vaporized in the gaps there between are condensed and are cooled and solidified on the surface of the sheet, thereby preventing appearance problems. Further, since the plasticizer vapor is easily taken into the sheet, less plasticizer vapor stays in the vicinity of the sheet and the mold that occurs when the technique of Japanese Patent Laid-Open No. 3-284935 is used. The above problem is unlikely to occur. Further, if the adhesion to the cooling roll is improved, the sheet cooling efficiency of the cooling roll is increased, so that the diameter of the cooling roll may be small and the amount of water supplied to the cooling roll may be small. Further, by pressing with a cooling roll, variations in thickness immediately after the die exit are corrected, and a sheet with excellent thickness accuracy is provided. The pressure must be set above the minimum pressure for these effects.

(2) When the roll pressure is set to a large value,
The ability of the sheet to bite into the roll deteriorates and a bank is formed, resulting in uneven thickness. Therefore, the upper limit of the pressure must be set so that the thickness does not vary.

Considering the above, taking a polyvinyl butyral sheet as an example, it is desirable to set the linear pressure to 2 to 10 kg / cm. When a double-sided belt is used, it is desirable to set the surface pressure to 1 to 3 kg / cm ² .

The sheet temperature immediately after the sheet is demolded in the cooling press machine is set to a temperature that satisfies the conditions (1) and (2) below. (1) The sheet is not released from the release point of the cooling roll,
The sheet needs to be cooled until it is no longer caught. In the case of a polybutyral sheet, it is desirable that the sheet surface temperature be 130 ° C. or lower.

(2) The temperature of the sheet is cooled so that the amount of expansion from the cooling roll releasing portion to immediately before the water tank due to the weight of the sheet itself is smaller than the stretching amount applied from the cooling roll to the water tank. Further, it is desirable to reduce the distance from the cooling roll release section to the water surface of the water tank, because the elongation amount due to the weight of the sheet becomes small, and the stretching amount in the water tank having the temperature distribution can be set small. . It is desirable to set the amount of stretching in the water tank to a small value because variations in thickness caused thereby are reduced. However, if the amount of stretching in the water tank is too small, the sheet sags, so it is desirable to set the amount of stretching from the cooling roll to the water tank to 1.01 to 1.1 times. In order to prevent self-weight sagging, when the stretching amount from the cooling roll to the water tank is 1.01 times and the distance from the mold releasing part of the cooling press device to the water tank is 20 cm, it depends on the extension viscosity of polyvinyl butyral. It is desirable that the temperature at the center of the sheet is 170 ° C. or lower.

Considering the above, taking a polyvinyl butyral sheet as an example, it is desirable to set the surface temperature of the sheet at the cooling roll releasing portion to 130 ° C. or lower and the center temperature to 170 ° C. or lower.

[0029]

EXAMPLES Next, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. In the following examples and comparative examples,
A thermoplastic resin (hereinafter referred to as PVB) containing a plasticizer having a composition shown in "Table 1" below was used.

[0030]

[Table 1]

The evaluation items and methods of the obtained thermoplastic resin sheet are as follows. "Sheet appearance defect rate" Foreign matter was detected using a foreign matter sensor (PKD, manufactured by Hutech Co., Ltd.) that continuously measures the transmittance of the thermoplastic resin sheet extruded per 12 hours, and the number thereof was counted. The foreign matter in the thermoplastic resin sheet extruded here is that the plasticizer vapor generated at the time of molding stays near the sheet and the mold, and the staying plasticizer vapor condenses at a temperature lower than the molding temperature, and the condensation The thing falls on the surface of the molten sheet, and after adhering, it is solidified by the cooling roll and the water tank, and the surface is scratched by the fall of the condensate.

"Thickness accuracy" The entire width of the sheet is divided into every 150 mm, and the thickness of each area is measured by using a contact type thickness meter (K306C manufactured by Anritsu Co.).
The maximum value of X value-MIN value was adopted.

"Heat shrinkage" width (die width direction) 1100
mm, length (extrusion direction) 200 mm sample 130
It was placed in an oven at 0 ° C. for 1 minute, and its dimensional change rate was measured.

Example 1 The manufacturing process shown in FIG. 1 was used. The chill press machine is two chill rolls. PV
B was extruded using a T-die having a width of 1500 mm and a die lip gap of 2.5 mm under the conditions of an extrusion temperature of 200 ° C. and a draw ratio of 2.0 from the die exit to the cooling roll, and a linear pressure of the cooling roll of 3 kg / Under cm ^2, the sheet was cooled by the cooling roll until the PVB sheet surface temperature at the time of peeling from the lower cooling roll became 110 ° C. (lower cooling roll side) and 130 ° C. (upper cooling roll side). However, upper cooling roll diameter 150m
m, and the lower cooling roll diameter was 300 mm. After cooling with a cooling roll, the draw ratio between the cooling roll and the water tank was set to 1.01, and the sheet was completely cooled by guiding it to a water tank having an average water temperature of 40 ° C to bring the sheet temperature to 40 ° C. ~ The stretch ratio in the take-up machine was set to 1.05, and the thermoplastic resin sheet was taken off. The thickness accuracy, heat shrinkage rate, and sheet appearance defect rate of the samples obtained in the above steps were evaluated. The results are shown in "Table 2".

Example 2 The manufacturing process shown in FIG. 2 was used. The cooling press device is a combination of a cooling roll and a cooling belt. PVB was extruded using a T-die having a width of 1500 mm and a die lip gap of 2.5 mm under the conditions of an extrusion temperature of 200 ° C. and a draw ratio from the die exit to the cooling roll of 2.0 times, and the linear pressure of the cooling roll was 3 kg / In cm, the sheet was cooled with a cooling roll until the PVB sheet surface temperature at the time of peeling from the cooling belt reached 130 ° C. However, the cooling roll diameter was 300 mm. After cooling with a cooling roll, the draw ratio between the cooling roll and the water tank was set to 1.01, and the sheet was completely cooled by guiding it to a water tank having an average water temperature of 40 ° C to bring the sheet temperature to 40 ° C. ~ The sheet was taken up with the draw ratio of the take-up machine set to 1.05 times. The thickness accuracy, heat shrinkage rate, and sheet appearance defect rate of the samples obtained in the above steps were evaluated. The results are shown in "Table 2".

Comparative Example 1 The manufacturing process shown in FIG. 3 was used. PVB width 1500mm, mold lip gap 2.5
mm, using a T-die, extruding temperature of 200 ° C., extruding at a draw ratio of 2.0 times from the die outlet to the cooling roll,
One side cooling was performed with a lower roll having a diameter of 300 mm without installing a press roll. However, it was cooled until the sheet surface temperature of the roll contact surface at the time of peeling reached 150 ° C. After cooling with a roll, the stretching ratio between the roll and the water tank was set to 1.01, and the sheet was completely cooled by guiding it to a water tank with an average water temperature of 40 ° C to bring the sheet temperature to 40 ° C. The stretching ratio in the machine was set to 1.05, and the sheet was taken off. The thickness accuracy, heat shrinkage rate, and sheet appearance defect rate of the samples obtained in the above steps were evaluated. The results are shown in "Table 2".

Comparative Example 2 The manufacturing process shown in FIG. 4 was used. PVB width 1500mm, mold lip gap 2.5
Using a T-die of mm, extruding at an extrusion temperature of 200 ° C., setting the draw ratio from the mold outlet to the water tank to 2.02 times,
The sheet was introduced into a water tank having an average water temperature of 40 ° C. to completely cool the sheet, and the sheet temperature was set to 40 ° C. Then, the stretching ratio in the water tank to the take-up machine was set to 1.05 times, and the sheet was taken out. The thickness accuracy, heat shrinkage rate, and sheet appearance defect rate of the samples obtained in the above steps were evaluated. The results are shown in "Table 2".

The thickness accuracy, heat shrinkage rate, and appearance defect rate of the sample sheet obtained in the above steps were evaluated. Also,
The thickness of each final product was measured. The results are shown in "Table 2" below.

[0039]

[Table 2]

From the results shown in the above "Table 2", the composition containing the thermoplastic resin and the plasticizer was extruded from the mold into a sheet shape, and the appearance was obtained by condensing the plasticizer by the cooling press device installed immediately after that. The manufacturing method of the present invention, which solves the above problems, corrects the variation in thickness, and cools to a sheet temperature that enables low-stretching in the water tank in the next step, and then cools the water tank with high cooling efficiency. Has excellent thickness accuracy,
It was confirmed that a sheet with a heat shrinkage rate and a defective appearance rate can be provided in a high production amount.

[0041]

According to the manufacturing method of the present invention, a composition containing a thermoplastic resin and a plasticizer is extruded from a mold onto a sheet, and the extruded sheet-shaped compact is preferably used in a cooling press machine. By conducting the drawing with a high draw ratio, it is possible to reduce the heat shrinkage ratio by decreasing the draw ratio in a region near the elasticity where the sheet temperature is low.

Further, according to the manufacturing method of the present invention, the following three excellent effects can be obtained by applying the pressure by the cooling press device to the sheet. (1) By eliminating the floating of the sheet with respect to the roll, the problems of the appearance of the sheet due to condensation of the plasticizer and the problems of appearance due to the condensation of the plasticizer are prevented. (2) Since the adhesion between the cooling press device and the sheet is increased, the cooling capacity of the cooling press device can be maximized. (3) It is possible to correct the thickness variation immediately after the die exit. Further, by cooling the cooling press device, the amount of stretching in the water tank having the temperature distribution of the next step can be set to the minimum, so that the variation in the thickness generated in the water tank can be minimized.

From the above, the present invention provides a method for producing a thermoplastic resin sheet containing a plasticizer which imparts excellent thickness accuracy, heat shrinkage and appearance.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a configuration of a manufacturing process used in an embodiment (1) of a manufacturing method of the present invention.

FIG. 2 is a schematic view showing a structure of a manufacturing process used in an embodiment (2) of the manufacturing method of the present invention.

FIG. 3 is a schematic diagram showing a configuration of a manufacturing process used in Comparative Example (1) of the manufacturing method of the present invention.

FIG. 4 is a schematic view showing the structure of a manufacturing process used in Comparative Example (2) of the manufacturing method of the present invention.

[Description of sign]

 1 Mold 2 Cooling Roll (Upper) 3 Cooling Roll (Lower) 4 Water Tank 5 Pulling Machine 6 Cooling Belt 7 Belt Induction Roll S Thermoplastic Resin Sheet

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display area // B29K 59:00 B29L 7:00

Claims (1)

[Claims] 1. A composition containing a thermoplastic resin and a plasticizer is fed to an extruder, and a shaped product obtained by shaping the composition into a sheet from a mold is extruded and then stretched by a cooling press machine. A method for producing a thermoplastic resin sheet containing a plasticizer, wherein the sheet is cooled while being pressed so as to be narrowed, the obtained sheet is introduced into a cooling water tank, and then stretched again.