KR20230013204A - Method of manufacturing simultaneous biaxial stretched film - Google Patents

Abstract

Disclosed is a method for manufacturing a simultaneous biaxially stretched film having good stretchability and excellent planarity as well as simplifying a process to reduce a time by performing simultaneous stretching in a biaxial direction using a biaxial stretching device. The method for manufacturing a simultaneous biaxially stretched film includes the steps of: (a) preparing raw materials; (b) manufacturing a sheet by co-extruding the raw materials; (c) manufacturing a film by simultaneously stretching the sheet in a biaxial direction while heating the sheet; and (d) heat-setting and cooling the film.

Description

Manufacturing method of simultaneous biaxially stretched film {METHOD OF MANUFACTURING SIMULTANEOUS BIAXIAL STRETCHED FILM}

The disclosure herein relates to a method for manufacturing a co-biaxially oriented film.

Unless otherwise indicated herein, material described in this section is not prior art to the claims in this application, and inclusion in this section is not an admission that it is prior art.

In general, polyethylene and polyester are used as biaxially stretched films because they are weak and impractical in an unstretched state, and biaxial stretching methods such as sequential biaxial stretching and simultaneous biaxial stretching are applied. However, the sequential biaxial stretching method is mainly used. The sequential biaxial stretching method is a method in which an unstretched sheet is first stretched in one direction and then stretched again in a right angle direction. There are two types of longitudinal and transverse stretching method, in which the unstretched sheet is first stretched in the longitudinal direction and then in the transverse direction, and the transverse stretching method in which the order is reversed. there is That is, since the stretching is sequentially performed in the transverse direction or the longitudinal and transverse directions, the residual forces generated during the transverse and longitudinal stretching are different, and the outer shape of the film is deformed due to the difference in shrinkage stress.

On the other hand, since the simultaneous biaxial stretching method stretches in the transverse and longitudinal directions simultaneously, the stretchability is better than the sequential biaxial stretching method, but the mechanism of the transverse stretching machine (tenter), which is a simultaneous biaxial stretching equipment, is relatively complex and disadvantageous to high speed. It is only used in very few cases. The tubular method makes a tubular unstretched sheet and simultaneously stretches it in the biaxial direction by blowing air into it in the same way as blowing a balloon. Although the film yield is high, thicker stains or flatness are produced compared to the above-mentioned tender method. It is often deteriorated, so it is hardly used for applications requiring high quality.

Therefore, there is an urgent need for research to produce a film of higher quality.

Republic of Korea Patent No. 10-0502261 (2005.07.11) Republic of Korea Patent No. 10-0666526 (2007.01.03)

It is intended to provide a method for producing a co-biaxially oriented film having a relatively simple process and excellent stretchability and excellent planarity.

In addition, it is not limited to the technical problems as described above, and it is obvious that other technical problems may be derived from the following description.

According to one embodiment of the disclosed subject matter, a method for manufacturing a co-biaxially stretched film includes (a) preparing a raw material, (b) preparing a sheet by co-extruding the raw material, (c) biaxially heating the sheet while heating the sheet. Preparing a film by simultaneously stretching it in the same direction; and (d) heat-setting and cooling the film, wherein the steps (c) and (d) are performed by a biaxial stretching device, wherein the biaxial stretching device The stretching device includes a heat supply unit for supplying heat to the sheet, and a transfer unit for transferring and stretching the sheet to the heat supply unit, wherein the heat supply unit includes a preheating section located at an inlet side of a passage through which the sheet is transported, It includes a stretching section for preparing a film by simultaneous biaxial stretching while heating the transferred sheet, a heat setting section for crystallizing the film, and a cooling section for cooling the film transferred from the heat setting section.

In addition, the raw material in step (a) may be at least one selected from polyethylene, polyethylene terephthalate, polypropylene and polyamide 66.

In addition, the step (b) may be performed by a T-die at a temperature of 200 ~ 300 ℃.

In addition, the stretching section may simultaneously stretch the sheet 5 to 10 times in the machine direction and the transverse direction at a rate of 4000 to 55000%/min under a temperature condition of 100 to 150 °C.

In addition, the heat setting section may be a temperature condition of 200 ~ 250 ℃.

According to one embodiment disclosed in the present specification, the method for manufacturing a simultaneous biaxially stretched film is simultaneously stretched in a biaxial direction using a biaxial stretching device, thereby simplifying the process and shortening the time, as well as having good stretchability and excellent flatness. It works.

1 is a process chart illustrating a method for manufacturing a co-biaxially stretched film according to an embodiment of the disclosure in the present specification.
2 is a schematic view illustrating a method for manufacturing a co-biaxially oriented film according to an embodiment of the disclosure in the present specification.
3 is a schematic diagram showing a biaxial stretching device.

Hereinafter, with reference to the accompanying drawings, look at the configuration and operation effects of preferred embodiments of the disclosure. For reference, in the drawings below, each component is omitted or schematically illustrated for convenience and clarity, and the size of each component does not reflect the actual size. In addition, like reference numerals refer to like components throughout the specification, and reference numerals for like components in individual drawings will be omitted.

Hereinafter, a method for manufacturing a co-biaxially oriented film disclosed in the present specification will be described in detail with reference to the drawings.

1 is a process diagram for explaining a method for manufacturing a co-biaxially stretched film disclosed herein, and FIG. 2 is a schematic diagram for explaining a method for manufacturing a co-biaxially stretched film disclosed herein. Hereinafter, a method for manufacturing a co-biaxially oriented film according to the present embodiment will be described with reference to this.

Referring to Figures 1 and 2, first prepare a raw material (S10).

In this embodiment, at least one selected from polyethylene (PE), polyethylene terephthalate (PET), polypropylene (PP) and polyamide 66 (Polyamide 66, PA 66) as a raw material, preferably polyethylene terephthalate (PET) and At least one selected from polypropylene (PP) may be used, and it is preferable to use one having an intrinsic viscosity in the range of 0.6 to 0.8. On the other hand, it is preferable to prepare the raw material by sufficiently drying it so that hydrolysis does not occur during co-extrusion, which will be described later.

Then, a sheet is manufactured by co-extruding the raw material (S20).

An amorphous sheet may be produced by co-extruding the raw material prepared in step S10 at a temperature of 200 to 300° C., which may be performed by a T-die. The sheet may be made of a single layer or a plurality of layers, but is not limited thereto. For example, when the sheet is formed of three layers, it may have a structure in which a second layer and a third layer are sequentially laminated on the upper surface of the first layer, and in this case, the first layer and the third layer are polyethylene terephthalate ( PET), and the second layer may be formed of polypropylene (PP).

If the co-extrusion temperature is less than 200 ° C, it may be difficult to mold into a desired shape, and if it exceeds 300 ° C, the strength is lowered and physical properties may be changed, which is not preferable. When the above-mentioned coextrusion temperature range is satisfied, the physical properties of the final product may be improved.

The T-die 100 used in this embodiment includes one or more channels, and the number of channels may correspond to the number of layers of the sheet.

Then, the sheet is simultaneously stretched in the biaxial direction while heating to prepare a film (S30).

The sheet prepared in step S20 is simultaneously 5 to 10 times, preferably 6 to 10 times in the longitudinal and transverse directions at a rate of 4000 to 55000% / min at a temperature condition of 100 to 150 ° C., preferably 120 to 130 ° C. A film can be prepared by stretching 7 times, and when stretching is performed under the above-mentioned temperature and speed ranges, the bowing rate can be reduced to 4% or less while imparting anti-shrinkage properties.

As described above, by co-biaxial stretching, the impact strength, transparency, and barrier properties of the film may be increased, and the crystallinity of the film may be increased during heat setting, which will be described later.

Finally, the film is heat-set and cooled (S40).

The stretched film in step S30 may be heat-set at 200 to 250° C. and slowly cooled at 50 to 100° C. During the heat setting process, molecules in the film are rearranged and structural defects caused by stretching are reduced, so thermal dimensional stability can be improved.

If the heat setting temperature is less than 200 ° C, the heat shrinkage rate may increase, and if it exceeds 250 ° C, strength and elastic modulus may decrease.

Meanwhile, steps S30 and S40 may be performed by a biaxial stretching device.

3 is a schematic diagram showing a biaxial stretching device.

Referring to FIG. 3 , the biaxial stretching device 200 includes a heat supply unit 210 and a transfer unit 230 .

The heat supply unit 210 may include a preheating section 211, a stretching section 213, a heat setting section 215, and a cooling section 217.

The preheating section 211 is located at the inlet side of the passage through which the sheet 1 is transported, and can preheat the transported sheet 1 under a temperature condition of 50 to 100°C.

In the stretching section 213, the film 2 is produced by simultaneous biaxial stretching while heating the sheet 1 transferred from the preheating section 211, but specifically, 4000 to 55000%/min at a temperature of 100 to 150 ° C. The film 2 may be produced by stretching 5 to 10 times simultaneously in the machine direction and the transverse direction at a speed of .

In the heat setting section 215 , the film 2 may be crystallized by heat-treating the film 2 at a temperature of 200 to 250° C. for 1 to 30 seconds. When the above-mentioned temperature conditions are satisfied, thermal dimensional stability may be increased.

The cooling section 217 may gradually cool the film 2 transferred from the heat setting section 215 at 50 to 100 °C.

The transfer unit 230 serves to transfer and stretch the sheet 1 to the heat supply unit 210, and includes a transfer chain 233 moved by a drive roller 231 and a sheet on the transfer chain 233. (1) or a fixing member 235 for fixing the film 2 may be included. For example, a fixing member 235 in contact with the sheet 1 or film 2 in order to prevent edge breakage of the sheet 1 or film 2 by the fixing member 235 formed in the form of a clip during co-biaxial stretching. An elastic member may be provided on the contact surface of the. On the other hand, one side of the elastic member may be surface-treated to increase the frictional surface between the sheet 1 or the film 2, and at this time, the surface roughness (Ra) does not size-limit its numerical range, but preferably ranges from 1 to 10. It may be 3 μm.

As described above, since the fixing member 235 is provided with an elastic member, a phenomenon in which the edge of the sheet 1 or the film 2 is broken is prevented, and thus the yield can be increased.

The disclosed content is only an example, and can be variously modified and implemented by those skilled in the art without departing from the subject matter of the claim claimed in the claims, so the protection scope of the disclosed content is limited to the specific not limited to the examples.

1: sheet 2: film
100: T-die 200: biaxial stretching device
210: heat supply unit 211: preheating section
213: stretching section 215: open setting section
217: cooling section 230: transfer unit
231: biaxial stretching device 233: conveying chain
235: fixing member

Claims (5)

(a) preparing raw materials;
(b) preparing a sheet by co-extruding the raw material;
(c) preparing a film by simultaneously stretching the sheet in a biaxial direction while heating the sheet; and
(d) heat-setting and cooling the film;
Steps (c) and (d) are performed by a biaxial stretching device,
The biaxial stretching device,
A heat supply unit for supplying heat to the sheet, and a transfer unit for transferring and stretching the sheet to the heat supply unit,
The heat supply unit includes a preheating section located at an inlet side of a passage through which the sheet is transported, a stretching section for preparing a film by simultaneous biaxial stretching while heating the sheet transferred from the preheating section, a heat setting section for crystallizing the film, and the heat supply unit. A method for producing a simultaneous biaxially stretched film comprising a cooling section for cooling the film transferred from the fixing section.
According to claim 1,
In step (a), the raw material is at least one selected from polyethylene, polyethylene terephthalate, polypropylene and polyamide 66.
According to claim 1,
Step (b) is a method for producing a simultaneous biaxially oriented film, characterized in that carried out by a T-die at a temperature of 200 ~ 300 ℃.
According to claim 1,
The stretching section is a method for producing a simultaneous biaxially stretched film, characterized in that the sheet is simultaneously stretched 5 to 10 times in the longitudinal and transverse directions at a rate of 4000 to 55000% / min at a temperature of 100 to 150 ° C.
According to claim 1,
The heat setting section is a method for producing a simultaneous biaxially stretched film, characterized in that the temperature condition of 200 ~ 250 ℃.

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