KR970008256B1 - Molding method for thermoplastic resin film - Google Patents

Abstract

In the production of biaxial drawing thermoplastic resin film, heat up the thermoplastic resin at the melting point. Extrude out of the extruder including a slit die, to a film shape on the cooling drum to produce pre-extended sheet and passing through the rollers with different rotation speed, and have it extended to 2.0-5.0 times toward the proceeding direction to get the primary extension film. This film is transferred to the center, where the both ends are held by clips and is secondly drawn to the vertical direction of the process. To give the plastic stability, this is heat treated with heat below the melting point.

Description

Manufacturing method of thermoplastic resin film

1 is a view for explaining the process of heat treatment after biaxially stretching the unstretched sheet according to the method of the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a thermoplastic resin film. Specifically, in the case of heat treatment after the primary stretching in the longitudinal direction and the secondary stretching in the transverse direction, the biaxially stretched thermoplastic resin film having excellent planarity by appropriately controlling the heat treatment temperature and time. It relates to a method of manufacturing.

Thermoplastic films, especially biaxially stretched polyester, polyamide, polyolefin, and polyvinyl films, are chemically and physically stable, have high mechanical strength, and are excellent in heat resistance, durability, chemical resistance, and electrical insulation. For magnetic recording media such as floppy disks, for capacitors for dielectrics, for insulating materials in electrical materials, for graphics such as photographic films, laminates, labels, etc., for OA related displays such as various cards, ribbons, printing, etc. It is widely used for general industry such as molding products such as stamping foil.

The biaxially stretched thermoplastic resin film used in this way is usually used for fixing to heat-melt resin, extruding it into a film form, quenching and molding into an unstretched sheet, and then stretching and cooling at a predetermined magnification in the longitudinal and transverse biaxial directions. Therefore, it manufactures by biaxially stretching and heat-processing it.

However, when the biaxially stretched thermoplastic resin film is manufactured according to the conventional method, it is impossible to obtain a film having good planarity due to the influence of residual stress and shrinkage stress during heat treatment. In the case of poor planarity, the tension is uneven when the film is wound. As a result, problems such as winding failure, poor appearance of the product, uneven coating in various coating processes, pint out during printing, and curling during lamination may occur. There is a problem of deterioration.

It is an object of the present invention to provide a method for producing a biaxially stretched thermoplastic resin film having excellent planarity by appropriately controlling heat treatment conditions during heat treatment of a film obtained by biaxially stretching an unstretched sheet in view of the above problems.

In the present invention to achieve the above object, in the method for producing a thermoplastic resin film comprising a step of heat treatment after the biaxial stretching of the unstretched sheet, so that the heat treatment satisfies the following formula (1), (2) and (3) It provides a method for producing a biaxially stretched thermoplastic resin film, characterized in that performed.

Tm-60 < T1 < … … … … … … … … … … … … … … … … (One)

50 <T1-T2 <130... … … … … … … … … … … … … … … … … … … (2)

5 <(T1-T2) / t <25... … … … … … … … … … … … … … … … … … … (3)

In the above formula, Tm is the melting temperature of the film (° C.), T1 is the initial heat treatment temperature (° C.), T2 is the final heat treatment temperature (° C.), and t is the heat treatment time (seconds).

1 is a view for explaining the process of heat treatment after biaxially stretching the unstretched sheet according to the method of the present invention.

At this time, what is necessary is just to select the temperature T between T1 and T2 suitably within the range of T2 <T <T1. And the heat treatment time (t) is preferably selected appropriately within the range of 5 to 30 seconds.

In the above formula (1), Tm-60 <T1 <Tm-10, the range of the initial heat treatment temperature is limited. When T1, the initial heat treatment temperature, is Tm-60 or less, the numerical stability of the film is lowered, and the initial temperature T1. In the case of Tm-10 or more, it is difficult to control the planarity of the film, and furthermore, the numerical stability effect is also lost.

In the method of the present invention, equation (2), 50 <T1-T2 <130, which is another limiting condition, limits the difference between the initial heat treatment temperature and the final temperature. Is impossible and the planarity is extremely poor. In addition, when T1-T2 is 130 or more, it is difficult to control the heat treatment temperature of the tenter and there is no further improvement in planarity.

Equation (3), 5 <(T1-T2) / t <25, which is the third condition, limits the time required for heat treatment. In other words, even if the heat treatment temperature is limited as in Equations (1) and (2), if it is out of the range of Equation (3) associated with the heat treatment time, the planarity of the film is poor or the productivity is lowered. Because you can't get it.

Hereinafter, a method of manufacturing a biaxially stretched thermoplastic resin film according to the method of the present invention will be described in detail.

The thermoplastic resin is first melted by heating to a temperature above the melting point, and then extruded in the form of a film on a cooling drum from an extruder including a slit die to prepare an unstretched sheet. The unstretched sheet thus prepared is passed between rollers having different rotational speeds and stretched 2.0 to 5.0 times in the advancing direction of the film to obtain uniaxially stretched films. At this time, the temperature of the sheet feed roller is preferably maintained at Tg + 10 ~ Tg + 50 ℃ (Tg: Yu transition temperature), the stretched sheet should be cooled to room temperature. The uniaxially stretched film is continuously transferred to the tenter, and then gripped at both ends with a clip to be secondaryly stretched in the direction perpendicular to the film traveling direction. In order to impart resin stability to the obtained biaxially oriented film, it is heat-treated at a temperature below the melting point, and then trimmed at both ends of the film through a take-up roll to wind the film in a winder to obtain a finished resin film product.

The film forming and drawing conditions that can be introduced in the method of the present invention can be used without limitation any method, for example, melt compression conditions, casting conditions, longitudinal stretching conditions, transverse stretching conditions, heat setting conditions, winding conditions of the thermoplastic resin Conditions may be appropriately selected and used as necessary. In addition, a stretching method other than the transverse stretching method after the longitudinal stretching may also be used. For example, all film forming methods and stretching conditions can be applied without exception without departing from the scope of the present invention, such as longitudinal stretching after longitudinal stretching, longitudinal multistage stretching, and transverse stretching after longitudinal stretching.

Thermoplastic resins that can be preferably used in the present invention include polyester resins such as polyethylene terephthalate, polyethylene-2,6-naphthalate, polyethylene isophthalate, polybutylene terephthalate, and polyamides such as nylon 6 and nylon 66. Polyolefin resins such as resins, polypropylene, polyethylene, and the like, polyphenylene sulfide, polyether sulfone, polysulfone or polyether polyether ketone, and the like, and many other monomers, copolymers, mixtures, composites, etc. Any resin capable of improving planarity by applying the method can be used without exception.

Hereinafter, the method of the present invention will be described in more detail with reference to specific examples and comparative examples. However, the present invention is not limited only to the following examples.

<Example 1>

The polyethylene terephthalate resin (melting temperature: 260 ° C.) was melted, extruded through a T-die and quenched on a cooling drum to obtain an unstretched sheet. The resulting unstretched sheet was stretched 3.5 times in the longitudinal direction at 95 ° C. using the roll speed difference between rolls to produce a uniaxially stretched film. The film was transferred to a tenter, and then both ends of the film were gripped with a clip to move the film at a temperature of 120 ° C. The biaxially stretched film was prepared by transverse stretching 3.5 times in the vertical direction. The resulting biaxially stretched film was subsequently subjected to heat treatment, but the initial temperature was 230 ° C and the terminal temperature was 160 ° C. The heat treatment time required was controlled to be 10 seconds. As a result of evaluating the planarity of the produced film, it was confirmed that the planarity is a very excellent film of A grade.

Comparative Example 1

A biaxially stretched thermoplastic resin film was obtained in the same manner as in Example 1 except that the heat treatment initial temperature was 200 ° C. and the end temperature was 180 ° C. in the tenter.

Comparative Example 2

A biaxially stretched thermoplastic resin film was obtained in the same manner as in Example 1 except that the heat treatment end temperature was 80 ° C. during the tenter heat treatment.

Comparative Example 3

A biaxially stretched thermoplastic resin film was obtained in the same manner as in Example 1 except that the heat treatment end temperature was 130 ° C. and the heat treatment time was 3 seconds.

<Comparative Example 4>

A biaxially stretched thermoplastic resin film was obtained in the same manner as in Example 1 except that the heat treatment end temperature was 130 ° C. and the heat treatment time was 30 seconds.

<Example 2>

The nylon 6 resin (melting temperature: 225 ° C.) was melted and extruded through a T-die and quenched on a cooling drum to obtain an unstretched sheet. The resultant unstretched sheet was stretched 3.3 times in the longitudinal direction at 75 ° C. using the roll-to-roll speed difference, to prepare a uniaxially stretched film, and then transferred to the tenter. The film was biaxially stretched by stretching 3.5 times in the vertical direction in the vertical direction. The resulting biaxially stretched film was subsequently subjected to heat treatment, and the heat treatment was performed at an initial temperature of 210 ° C and a final temperature of 130 ° C. The heat treatment time required was controlled to be 10 seconds. As a result of evaluating the planarity of the produced film, it was confirmed that the planarity was a very good film with A grade.

Comparative Example 5

A biaxially stretched thermoplastic resin film was obtained in the same manner as in Example 1 except that the initial heat treatment temperature in the tenter was 190 ° C. and the end temperature was 170 ° C.

Comparative Example 6

A biaxially stretched thermoplastic resin film was obtained in the same manner as in Example 2 except that the end-to-heat treatment was performed at 80 ° C. during the heat treatment in the tenter.

Comparative Example 7

A biaxially stretched thermoplastic resin film was obtained in the same manner as in Example 2 except that the heat treatment time was 3 seconds during the heat treatment in the tenter.

<Comparative Example 8>

A biaxially stretched thermoplastic resin film was obtained in the same manner as in Example 2 except that the end-to-heat treatment was performed at 130 ° C. and the heat treatment time was 20 seconds.

The planarity of the films prepared according to the above Examples and Comparative Examples was evaluated according to the following method.

(Flatness evaluation)

After the heat treatment was completed, the film of 1m × 1m area was unfolded on a black background plane and left for 30 minutes to completely remove the air between the film and the plane, and then the planarity of the film was visually observed. As a result, the area of the poor planarity of the film was expressed in% compared to the total film area, and the goodness of film planarity was evaluated, which was classified into 5 grades as follows.

*. A: 5% or less of defective film planarity

*. B: 5 ~ 10% defective film planarity

*. C: 10 to 30% of film flatness defects

*. D: 30 to 50% of defective film planarity

*. E: 50% or more of defective film planarity

The properties of the films prepared according to the above Examples and Comparative Examples are shown in Table 1 together with the heat treatment conditions. In Table 1, T1 represents the initial heat treatment temperature, T2 represents the final heat treatment temperature, and t represents the heat treatment time (seconds).

TABLE 1

As a result of evaluation of the performance of the films prepared in Examples and Comparative Examples, as shown in Table 1, the film produced according to the method of the present invention, which controls the initial temperature, the end temperature, and the heat treatment time during heat treatment, is limited within a certain range. It can be seen that it has excellent planarity.

In this example, the planarity of the biaxially stretched polyester and polyamide films was evaluated, and it should be understood that this can be applied to other resin films.

The biaxially stretched thermoplastic resin film having excellent planarity produced according to the method of the present invention is very practical that can be variously used for packaging, magnetic, lamination, montage, graphic art, and the like.

Claims (3)

A method for producing a thermoplastic resin film comprising a step of biaxially stretching an unstretched sheet, followed by heat treatment, wherein the heat treatment is performed to satisfy the following formulas (1), (2) and (3). Method for producing a resin film. Tm-60 < T1 < … … … … … … … … … … … … … … … … (One) 50 <T1-T2 <130... … … … … … … … … … … … … … … … … … … (2) 5 <(T1-T2) / t <25... … … … … … … … … … … … … … … … … … … (3) In the above formula, Tm is the melting temperature of the film (° C.), T1 is the initial heat treatment temperature (° C.), T2 is the final heat treatment temperature (° C.), and t is the heat treatment time (seconds). The method of claim 1, wherein the heat treatment time (t) is in a range of 5 to 30 seconds. The method for producing a thermoplastic resin film according to claim 1, wherein the thermoplastic resin is a polyester-based or polyamide-based resin.