JPS6044319A - Manufacture of sheet or film of crystalline thermoplastic resin - Google Patents

Abstract

PURPOSE:To obtain a sheet or film of a crystalline thermoplastic resin excellent in transparency and stiffness whose production is easily controlled, by melt-extruding a nucleator-containing thermoplastic resin into the form of a film, and cooling the film by cooling water that is running. CONSTITUTION:A filmy thermoplastic resin 2 that is melted and extruded from a T-die 1 is introduced into a slit 3 through which water is running. The slit 3 is in communication with an upper water tank 4 located below the T-die 1. Since cooling water is running from the water tank 4, when the filmy thermoplastic resin is passed through the slit 3, the resin is cooled by the cooling water. Then the filmy resin is passed into a lower water tank 5, is forced to be positioned at the center of the slit by semisubmerged pinch rolls 6 and is driven thereby so that the filmy resin is traveled at a certain speed to produce an excellent sheet or sheet the accuracy of the thickness of which is secured.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a crystalline thermoplastic resin sheet or film.

Conventionally, methods for producing quenched sheets of crystalline thermoplastic resins such as polypropylene resins, such as chill roll method and water cooling method, are known. However, during high-speed molding, the chill roll method introduces air between the roll and the molten resin film, and the adhesion between the roll and the molten resin film is poor.
There are drawbacks such as unevenness and wrinkles, and in the case of thick sheets, curling occurs due to the cooling difference between the front and back sides of the molten resin film, and a decrease in transparency 9 surface gloss due to insufficient rapid cooling. be. In addition, in the water cooling method, heat dissipation from the molten resin film occurs locally on the cooling water surface, causing uneven cooling due to ripples and shaking of the water surface, and haze spots due to insufficient cooling. Unevenness or deterioration may occur,
The disadvantage is that high-speed molding cannot be performed.

Usually, the water cooling method has the advantage of being able to cool the sheet etc. more efficiently than the roll method. Therefore, methods have been proposed to improve the drawbacks of the water cooling method described above, such as heat treatment under specific conditions or water cooling under specific conditions. (However, the sheets etc. obtained by these methods did not have sufficient transparency. Furthermore, in the water cooling method, the non-uniformity of the water flow greatly affected the transparency etc. of the sheets etc. obtained. , there are major manufacturing problems.

Therefore, the present inventor has completed the present invention as a result of research into a method for producing a thermoplastic resin sheet or film that solves the above problems, is easy to control in production, and has excellent transparency, rigidity, etc.

That is, the present invention provides a method for producing a crystalline thermoplastic resin sheet or film, which comprises melt-extruding a crystalline thermoplastic resin containing a nucleating agent into a film and cooling it with flowing cooling water. It is.

There are various types of crystalline thermoplastic resins used in the present invention, such as ethylene polymers, propylene polymers,
Copolymers of ethylene and other α-olefins, propylene and other α-olefins, such as ethylene and 4 carbon atoms
There are polyethylene resins such as copolymers with the above α-olefins.

The copolymer of propylene and other α-olefin preferably has a propylene content of 80% or more.

Examples of crystalline thermoplastic resins other than polyolefin resins include polyamides such as nylon-6 and nylon-6,6; polyesters such as polyethylene terephthalate and polybutylene terephthalate.

Next, the nucleating agent plays a role in improving the surface properties, transparency, rigidity, etc. of the sheet, etc., and particularly in the method of the present invention, it has a great effect on preventing haze spots. As the nucleating agent used in the present invention, specifically aromatic mono-
or poly-carboxylic acids such as benzoic acid, p-tert-butylbenzoic acid, O-methylbenzoic acid, 2,4
-dimethylbenzoic acid, α-naphthoic acid, 1m-chlorobenzoic acid, 9m-nitrobenzoic acid, O-aminobenzoic acid.

Isophthalic acid, terephthalic acid, monomethylphthalate phthalic acid, trimellitic acid, pyromellitic acid, anhydrides or metal salts thereof, etc.; aromatic sulfonic acid compounds such as benzenesulfonic acid.

2.5-Dichlorobenzenesulfonic acid, 1m-xylenesulfonic acid, α-naphthalenesulfonic acid, and metal salts thereof, etc.: Aliphatic or aromatic oxyacids, such as malic acid, tartaric acid, citric acid, salicylic acid, and metal salts thereof. etc.: saturated aliphatic or cycloaliphatic dicarboxylic acids such as oxalic dimalonic acid, succinic acid, adipic acid, speric acid, sebacic acid and their anhydrides. Cis-cyclohexane-1,4-dicarboxylic acid and metal salts thereof; nuclear-substituted aliphatic monocarboxylic acids such as monophenylacetic acid, diphenylglycolic acid, phenyldimethylacetic acid, cyclohexylic acid and metal salts thereof, etc. Compounds such as dibenzylidene sorbitol, dibenzylidene xylitol, dibenzylidene perseitol, dibenzylidene mannitol, etc., and compounds in which the benzene nucleus of these compounds is substituted with an alkyl group, an alkoxy group, a halogen atom, etc.; inorganic powders, e.g. Examples include silica, talc, and zeolite. Here, as the metal salt, salts of metals belonging to Groups 1 to 3 of the periodic table, such as lithium, sodium, potassium, magnesium, calcium, zinc, and aluminum, are used.

The blending amount of the nucleating agent is [100
5 to 1% by weight, preferably [105 to [L5% by weight]. If the blending amount is 1,005% by weight, sufficient effects cannot be obtained, and even if it is added in excess of 1% by weight, no corresponding improvement in effect is observed, which is uneconomical.

In the present invention, a surfactant and a lubricant are added as necessary to the crystalline thermoplastic resin containing a nucleating agent.

Antioxidants and the like can be added.

The present invention is a method for producing a sheet or film using the above-mentioned raw materials by a water cooling method. The method of melt-extruding the raw resin into a film and cooling it with flowing cooling water can be carried out in various ways.

First, as a method for melt-extruding the resin into a film, a T-die method, which is commonly used for forming sheets, etc., can be applied.

Next, the film-like resin is cooled by flowing cooling water by flowing the cooling water into a slit to bring it into a fluid state, and then introducing the molten film-like resin into the slit.

The material of the slit part is not particularly limited and may include metal, plastic, wood, cloth, etc. In addition, the slit part can be made with a pair of endless belts or a pair of rolls with a predetermined distance between them (+1)
may be completed. In particular, by having two or more slits, it is possible to obtain an excellent product with even higher productivity.

Cocurrent flow or countercurrent flow with respect to the fluidized Fi film resin may be used, but cocurrent flow is preferable from the viewpoint of productivity and the like.

You can use only water as cooling water, or water and organic water as cooling water.
(An aqueous solution containing a thickener is used, but
Aqueous solutions with added thickeners provide more uniform cooling.

It is preferable in terms of surface smoothness. Here, various organic thickeners can be used, including natural polymer substances, semi-synthetic products, and synthetic products. Natural polymeric substances include starches such as Japanese starch, potato starch, and wheat starch; mannans such as konjac; sea gravels such as agar and sodium alginate; vegetable mucilages such as gum tragacanth and gum arabic; microbial mucilages such as; proteins such as glue, gelatin, casein, and collagen; Semi-synthetic products include cellulosic materials such as viscose, methylcellulose, and carboxymethylcellulose; soluble starch.

There are starch-based substances such as carboxymethyl starch and dialdehyde starch. In addition, synthetic products include polyvinyl alcohol, sodium polyacrylate, polyethylene oxide, and the like.

On the other hand, examples of inorganic thickeners include CVi silica sol, alumina vine, clay, water glass, and various metal salts.

It is also possible to use an aqueous solution prepared by adding these thickeners to water, or a viscous substance such as polyethylene glycol, polypropylene glycol, silicone oil, etc. alone.

The viscosity of the aqueous solution with added thickener should be between 2 and 3000 centivoise (CP), preferably between 3 and 1000 CP. Also 1. The temperature of the cooling water is -10C to +50C
is preferable, especially when manufacturing sheets with a thickness of 0.2111I+ or more, the liquid temperature is 20t? Below, particularly preferably 1
Setting the temperature below 0C is effective in preventing the occurrence of haze spots.

FIG. 1 and FIG. F4s2 are explanatory diagrams showing aspects of an apparatus for carrying out the method of the present invention. The present invention will be explained in detail with reference to FIG. A slit 3 through which cooling water flows through a film-like thermoplastic resin 2 extruded in a molten state from a T-die 1.
to be introduced. This slit 3 is connected to an upper water tank 4 located below the T-die 1, and usually has a length of 5 to 100 feet, but a shorter length is preferable. In the upper water tank, it is necessary that the water from the membrane-like thermoplastic resin introduction part flow by 1 ttb, and the water level should be as low as possible, and generally 7 or less is preferable. When the water level reaches 10, boiling silicon, haze spots, and curls occur on the obtained sheet, and the total haze becomes 25 to 28%.
I don't like it. Since cooling water flows from the water tank 4, the film-like thermoplastic resin is cooled by the cooling water when passing through the slit 3. That is, the cooling water flows in parallel on both sides of the resin film, and is efficiently cooled. It is desirable that the flow rate of this cooling water be close to the traveling speed of the film-like resin.

Furthermore, the slit 3 competing for connection with the aquarium is not limited to the one-stage case as shown in Fig. 1, but may be two-stage as shown in Fig.
It is also possible to cool the resin film in multiple stages of three or more stages. When using multistage slits of two or more stages, the first
It is necessary to set the water level as low as possible for the slits in the second stage, but for the slits after the second stage, even if the water flow is disturbed, the quality of the sheet or film will not be affected much, so special consideration must be given to adjusting the water level. There is no need to do this.

Next, the film-like resin thus heated and cooled is sent to the lower water tank 5. As shown in the figure, the lower water tank 5 contains a semi-submerged pressure roll 6 whose lower part is submerged in water.
This roll 6 is used to always position the film-like resin at the center of the slit, keep the running speed of the film-like resin constant by driving it, and ensure the accuracy of the thickness of the sheet or film. It will be done.

The film-like resin that has passed through the semi-submerged pressure roll 6 is cooled by cooling water in a water tank 5 and then taken off by a take-up roll 7. Alternatively, as shown in FIG. 2, the cooled film-like resin does not pass through the water tank but instead passes through the guide roll 12. It may be taken over by the take-up roll 7 via the drain roll 16. The nucleating agent-containing crystalline thermoplastic resin sheet or film of the present invention is obtained by winding up the material passing through the take-up roll 7 on a take-up roll. Flowboard.

10 is a cooler, and 11 is a pump.

C) It is preferable to perform heat treatment before winding the film to prevent curling.

In that case, the heating temperature is, for example, 80 to 1.3 DC for polypropylene resin, preferably 120 to 13
It is 0C.

According to the improved water cooling method of the present invention, it is possible to obtain a non-oriented sheet or film with excellent transparency and surface gloss by using a crystalline thermoplastic resin as a raw material. Moreover,
The surface of the sheet has no irregularities or haze spots, and a uniform and highly rigid sheet with no wrinkles or uneven thickness can be obtained. Ota,
It is possible to produce relatively thick sheets. In addition, another feature of the present invention is that there is no trouble caused by adhesion of the nucleating agent to the touch roll or chill roll as in the two-tuna roll method or the air knife method.

As mentioned above, the sheets and films obtained by the method of the present invention have good transparency, surface gloss, and rigidity.
It is suitable for packaging materials such as foods and pharmaceuticals.

Moreover, it can also be used as a raw material for in-phase forming such as air pressure forming, roll rolling forming, and stretching forming.

Next, the present invention will be explained by examples.

Example 1 Polypropylene (density [1,91 P/d, MI 2.
dibenzylidene sorbitol i [1
2 weight ratio compounded pellets were extruded at a resin temperature of 260C using a T-die extrusion device (extruder 608φ, L/D=28°, die width 5
5 Qm, Grip gap 151111). After cooling the extruded molten resin film by introducing it into a 2 gm wide slit through which cooling water flows, it is taken out through a water tank.
A polypropylene sheet was obtained.

In addition, the temperature of the cooling water was [4C, Surin] - The water surface height of the second part of J was 5 directions, and the slit height was Fi5 [1st direction]. Table 1 shows the measurement results of the physical properties of the obtained sheet.

Example 2 A sheet was obtained in the same manner as in Example 1 except that 0.2 weight of aluminum benzoate was added instead of dibenzylidene sorbitol. The results are shown in Table 1.

Comparative Example 1 A sheet was prepared in the same manner as in Example 1 except that dibenzylidene sorbitol was not added. The results are shown in Table 1.

Example 3 Polypropylene (dense [(L 91 P/d, MI 2
．． 0! ? /10 minutes) dibenzylidene sorbitol i [
L2 weight ratio 1. The resin temperature of the pellet is 250t? '
Extrusion was performed using a cT-die extrusion plate (same as in Example 1).The extruded molten resin film was soaked in cooling water (water temperature 16C).
After the water is introduced into the first stage slit (width 2m, length 45m) 17, cooling water (water temperature 20C) is introduced into the second stage t', which is provided below the first stage slit with a corner 501. Introduced into the slit (width 4 em * length 101) 1
After being cooled for 1 to 30 minutes, as shown in FIG. 2, the polypropylene sheet was taken off by a take-up roll via a guide roll and a drain roll to obtain a polypropylene sheet. Table 1 shows the measurement results of the physical properties of the sheet.

Example 4 A sheet was obtained in the same manner as in Example 3, except that water containing carboxymethyl cellulose α001 by weight was used as cooling water. The results are shown in Table 1.

Comparative Example 2 In Example 3, a sheet was obtained in i~ in the same manner as in Example 6 except that dibenzylidene sorbitol was not blended. The results are shown in Table 1.

Example 5 In Example 4, the sheet obtained was subsequently heat treated using four rolls each having a diameter of 300 mm and heated to 120C. The results are shown in Table 1.

[Brief explanation of the drawing]

FIGS. 1 and 2 are explanatory diagrams showing aspects of an apparatus for carrying out the method of the present invention. 1... T-die, 2... Nucleating agent-containing film-like thermoplastic resin, 3.3'... Surin), 4.4'... Upper water tank. 5... Lower water tank, 6... Half-immersed pressure roll, 7...
Take-up roll patent applicant Idemitsu Petrochemical Co., Ltd. Figure 1 Figure 2

Claims (1)

[Claims] (1) A method for producing a crystalline thermoplastic resin sheet I or film, which comprises melt-extruding a crystalline thermoplastic resin containing a nucleating agent into a film and cooling it with flowing cooling water. . (2) The manufacturing method according to claim 1, wherein the crystalline thermoplastic resin is a polypropylene resin. (6) A patent claim in which the cooling water is introduced into the slit in parallel with the flow of the resin film. The manufacturing method according to item 1.