KR101525826B1 - White film and A method of manufacturing Opaque White film - Google Patents

Abstract

More specifically, the present invention relates to a white film and a method for producing the same, and more particularly, to a white film and a method for producing the same, which comprises: a) adding 5 to 25 parts by weight of an amorphous polyester resin to 100 parts by weight of a polyester resin, B) preparing a sheet for extruding a mixture of the masterbatch and the polyester resin; c) stretching the prepared sheet; d) heat treating the stretched sheet with a tenter of at least five stages; And e) heat-setting the heat-treated sheet. The white film produced by the above-mentioned method has a crystallization rate measured at 210 ° C isothermal conditions of 60 to 300 Sec., Thereby minimizing the occurrence of crystallization in the production of a film, thereby preventing the occurrence of breakage of the film, and a white film having good workability and a method for producing the same.

White film, barium sulphate, rounded short, polyester, amorphous polyester

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a white film and a manufacturing method thereof,

The present invention relates to a white film and a method of manufacturing the same, and more particularly, to a white film excellent in opacity for a billboard, a placard, a label, a packaging material for food or beverage, and a method for manufacturing the same.

Currently, paper, white plastic film and the like are generally used as a base material for labels, handbills, cards, calendars and the like, and polyvinyl chloride, polyolefin, polystyrene and the like are used as plastics.

In general, a polyolefin film containing inorganic fine particles has been used as a base material for paper substitute. However, polyolefin films have limitations in terms of mechanical strength, heat resistance, weatherability, and numerical stability, It is a trend that paper is used as a substitute for paper.

Polyester is physically and chemically stable, has high mechanical strength, is excellent in heat resistance, durability, chemical resistance and electrical insulation, and is widely used for manufacturing medical and various industrial products. Among them, polyethylene terephthalate has excellent properties such as elasticity, dimensional stability and flattening, and is widely used for various applications such as magnetic recording media, condenser, food or beverage packaging, photo film, label, . It is also used as a substitute paper for various magnetic cards (credit and communication cards), printer paper cards, bar codes, posters, calendars, maps, cardboard, display boards, white plates, photo paper, copy paper and special purpose printing publications.

Recently, a method of adding white inorganic particles having a high refractive index has been studied as a method for controlling the high transparency of a polyester film having such high transparency and surface gloss to use the film for various purposes. For example, in Korean Patent Publication No. 2000-0061237, inorganic particles such as calcium carbonate are added to polyester, but since calcium carbonate gives an excessively high gloss of the surface of the film, it causes eye fatigue. Therefore, The film becomes stiff and the workability is deteriorated. Korean Patent No. 773705 discloses a white film having low transparency by adding barium sulfate alone to polyester. However, since the particle size distribution of barium sulfate particles is not controlled, it is difficult to produce a white film having uniform physical properties If the particle content is increased, the crystallization proceeds excessively, which may cause a problem of fracture at the time of stretching. The amount of the pores formed in the film is excessive due to the added inorganic particles, the strength of the film is lowered, and the film is frequently broken during film stretching.

Disclosure of the Invention In order to solve the above-mentioned problems, an object of the present invention is to provide a white film having excellent hiding power and whiteness, minimizing the occurrence of crystallization during film production and having no breakage of film, good workability and excellent mechanical strength, Method.

In order to achieve the above object, the present invention relates to a method for producing a white film, which comprises the steps of: a) adding 5 to 25 parts by weight of an amorphous polyester resin to 100 parts by weight of a polyester resin, Masterbatch manufacturing steps comprising barium particles; b) a sheet production step of extruding a mixture of the master batch and the polyester resin; c) stretching the prepared sheet; d) heat treating the stretched sheet with a tenter of at least five stages; And e) thermally fixing the heat-treated sheet.

The white film prepared as described above has a crystallization rate of 60 to 300 seconds measured under an isothermal condition at 210 캜 using DSC. The crystallization is minimized during the production of the film, so that no breakage of the film occurs, A method for producing a good white film is provided.

Hereinafter, preferred embodiments of the present invention will be described in detail. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted so as to avoid obscuring the subject matter of the present invention.

The terms "about "," substantially ", etc. used to the extent that they are used herein are intended to be taken to mean an approximation of, or approximation to, the numerical values of manufacturing and material tolerances inherent in the meanings mentioned, Accurate or absolute numbers are used to help prevent unauthorized exploitation by unauthorized intruders of the referenced disclosure.

First, the present invention relates to a process for producing a masterbatch comprising: a) adding 5 to 25 parts by weight of an amorphous polyester resin to 100 parts by weight of a polyester resin, adding barium sulfate particles having a refractive index of 1.6 to 1.7, kneading them in a twin- Step < / RTI >

The polyester resin used for the white film according to the present invention preferably has an intrinsic viscosity of 0.60 to 0.70. When the intrinsic viscosity is less than 0.60, the strength of the film can not be increased enough to satisfy the strength of the film at the time of processing. As a result, the polyester resin often breaks during the stretching to deteriorate the productivity. When the intrinsic viscosity exceeds 0.70, The melt viscosity is so high that the productivity in the subsequent step is greatly reduced due to the difficulty in the film forming process such as the increase of the extrusion pressure.

The polyester resin used for the white film according to the present invention is not particularly limited, but it is preferable to use polyethylene terephthalate (PET) in consideration of thermal stability and physical properties of the film. The PET is obtained by condensation polymerization of an acid component containing a dicarboxylic acid as a main component and a glycol component containing an alkyl glycol as a main component. As the main component of the dicarboxylic acid, terephthalic acid or its alkyl ester or phenyl ester is mainly used. The main component of the glycol component is ethylene glycol.

In one embodiment of the present invention, the amorphous polyester resin is a mixture of polyethylene terephthalate prepared by polymerizing terephthalic acid (TPA) and ethylene glycol (EG) with terephthalic acid (TPA) , And other diol components in place of ethylene glycol (EG), and mixtures thereof. The amorphous polyester resin is obtained by copolymerizing 100 parts by weight of polyethylene terephthalate contained in the master batch To 5 to 25 parts by weight.

In the present invention, the amorphous polyester resin is a copolymer of polyethylene terephthalate (TPA) and ethylene glycol (EG), 10 to 20 mol% of other diol components are copolymerized. Examples of the acid component include di-phthalic acid such as isophthalic acid, oxyethoxybenzoic acid, adipic acid, sebacic acid and 5-sodium sulfoisophthalic acid. An acid component selected from the group consisting of a maleic acid and an ester-forming derivative thereof can be used. Examples of the diol component include propylene glycol, trimethylene glycol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, 1,4-bisoxyethoxybenzene, bisphenol, polyoxyethylene glycol, Neopentyl glycol, neopentyl glycol, and mixtures thereof.

In the present invention, when the content of each component is less than 10 mol%, the effect of delaying the crystallization due to amorphousness is insufficient. When the content is more than 20 mol%, the amorphousness is too large, and the raw material drying process becomes difficult.

Further, it is preferable that the co-polymer containing amorphous polyester used in the white film of the present invention has an intrinsic viscosity of 0.60 to 0.80. When the intrinsic viscosity of the copolymer is less than 0.60, the strength of the film can not be increased sufficiently during processing, so that breakage occurs frequently during stretching to deteriorate the productivity, If it exceeds 0.80, the melt viscosity becomes very high, and the productivity in the subsequent step is greatly reduced due to the difficulty in the film forming process such as the increase of the extrusion pressure.

Particularly, in step a), the amorphous polyester resin may be contained in an amount of 5 to 25 parts by weight based on 100 parts by weight of the polyester resin contained together. By using the amorphous polyester resin, the amorphous polyester resin has satisfactory opacity And at the same time, it is possible to reduce the occurrence of breakage of the film in a film production process to be described later. In addition, there is an advantage that whiteness and opacity of a white film are uniformized in a lot by suppressing non-uniform stretching due to excessive crystallization. If the content of the amorphous polyester resin is less than 5 parts by weight, the effect of inhibiting the crystallization is insufficient and the effect of improving the fracture is insufficient. If the content of amorphous polyester resin is more than 20 parts by weight, the effect of inhibiting crystallization is too large, The value becomes insufficient.

In one embodiment of the present invention, barium sulfate which is compounded after kneading in a twin-screw extruder by charging barium sulfate particles having a refractive index of 1.6-1.7 is used. When the refractive index is less than 1.6, the gloss level deviates from the required level, If it is exceeded, the absorbed light is increased, and the required whiteness may be lowered.

Specifically, the barium sulfate of the present invention has an average particle diameter of 1.0 to 1.5 占 퐉 according to the circle equivalent diameter, no particles having a particle diameter of 0.0001 to 0.3 占 퐉, no particles having a volume of 5 volume% or less, no particle having a particle diameter of 3.0 to 10.0 占And the ratio of the long diameter to the short diameter is 0.7 to 1.0 and the volume distribution of the particle size distribution is from 95 to 100 volume% of 0.3 to 3 占 퐉. If the average particle diameter of the barium sulfate is less than 1.0 占 퐉, the dispersibility of the particles may deteriorate due to the aggregation of barium sulfate particles and aggregation, By weight, the particle size becomes too large, and the pore size at the time of stretching by the film becomes large, resulting in poor operation, and the whiteness and opacity may be lowered.

When the distribution of particles having a particle diameter of 0.0001 to 0.3 μm by the equivalent circle exceeds 5 vol% and the particle diameter of 3.0 to 10.0 μm exceeds 5 vol%, that is, when the particle size distribution falls within a certain range The size of the particles becomes uneven and the size and frequency of the pores are also uneven when the film is stretched to cause a failure of the film to cause breakage of the film and it becomes difficult to obtain uniform physical properties of the final film . It is more preferable that the above-mentioned 0.0001 to 0.3 占 퐉 particles have a particle diameter of 0.3 占 퐉 or less by circle equivalent diameter, and the 3.0 to 10 占 퐉 particle distribution is 3.0 占 퐉 or more. Respectively. Further, it is preferable that the particle diameter of the particles of 0.3 탆 or less and the particle diameter of 3.0 탆 or more are contained in an amount of 0.001-5% by volume based on the circle equivalent diameter, and more preferably, there is no particle having the particle distribution in the above range . The ratio of the long diameter to the short diameter of the barium sulfate of the present invention is preferably 0.7 to 1.0, and the ratio of the long diameter to the short diameter in the above range is more preferably the shape of the barium sulfate of the present invention is near to spheres. It is possible to improve pore formation and workability of the resulting film and to improve the physical properties and whiteness of the final film.

The barium sulfate contained in the white film of the present invention is used for improving the degree of whiteness and opacity (hiding power). The barium sulfate which is an inorganic substance of the present invention forms voids. These voids absorb light of a specific wavelength Without any work, the light is uniformly diffused to sufficiently bleach the film to improve whiteness. The shape, average particle size or particle size distribution of the barium sulphate influences whiteness, gloss, opacity and operational stability.

In general, in the particle group constituting the particle, the particles are composed of particles irregular in shape and uneven in size. In order to show the particle size of such irregularly shaped particles, diameter. Here, the circle equivalent diameter means the diameter of a circle having the same width as the projection width of the particle.

Accordingly, by controlling the average particle diameter or the particle size distribution, shape, and refractive index of the barium sulfate as described above to uniformize and minimize the pore size, there is no occurrence of breakage during stretching of the film, and a white film having satisfactory whiteness, opacity and gloss Can be obtained.

The white film according to the present invention may be prepared by directly incorporating barium sulfate into the polyester resin in extrusion, but it is more preferable that the white film is applied in the form of a master batch containing barium sulfate in the polyester resin.

The content of barium sulfate of the present invention may be in the range of 50 to 150 parts by weight of barium sulfate relative to 100 parts by weight of the polyester resin. That is, a polyester resin and 50 to 150 parts by weight, more preferably 70 to 120 parts by weight, of barium sulfate are added to a twin-screw extruder hopper per 100 parts by weight of the polyester resin to prepare a compounding chip, Can be manufactured. If the amount of the barium sulfate is less than 50 parts by weight, the whiteness or hiding property of the film can not be imparted even if a large amount of masterbatches are added during the production of the film. If the amount exceeds 150 parts by weight, This may cause breakage during stretching.

and b) a sheet production step of extruding a mixture of the master batch and the polyester resin. The master batch may be contained in an amount of 10 to 100 parts by weight, preferably 30 to 70 parts by weight, and more preferably 50 to 60 parts by weight based on 100 parts by weight of the polyester resin. If the master batch containing barium sulfate is less than 10 parts by weight, the whiteness or hiding ability of the film can not be imparted. If the master batch contains more than 100 parts by weight, breakage may occur during stretching.

The polyester resin is a polyester resin having an intrinsic viscosity of 0.6 to 0.7 without adding particles in the polymerization step. It is preferable that the mixture of the master batch and the polyester resin is dried at a moisture content of 50 to 100 ppm before being extruded.

The dried mixture is put in an extruder, melted, extruded from a T-die, quenched by a casting drum having a surface temperature of 10 to 50 DEG C, and solidified to produce a sheet having a thickness of 1,000 to 2,000 mu m. The quenching can keep the amorphousness of the film to a maximum, and the occurrence of breakage of the film can be reduced.

c) uniaxially or biaxially stretching the prepared sheet. The c) stretching step is a stretching step in which the sheet is stretched 2 to 4 times in the machine direction (MD) at 85 to 110 캜, cooled to 20 to 35 캜, stretched at 110 to 140 캜 to 3.0 to 4.0 times in the transverse direction (TD) Biaxial stretching is preferable.

By controlling the shape and size of barium sulphate contained in the film of the present invention, it is possible to produce a stable film at a temperature lower than the conventional stretching temperature at a high temperature of 140 ° C or less.

It is preferable that the stretching temperature in the machine direction is higher than the Tg of the polyester resin, that is, 85 to 110 캜. When the stretching temperature in the machine direction is less than 85 캜, the stretching stress is large, There is a high problem, and if it exceeds 110 DEG C, the thickness adjustment becomes difficult. When the stretching ratio in the machine direction is less than 2 times, the thickness is inferior and the physical properties are deteriorated. When the stretching ratio is more than 4 times, there is a high possibility of breakage in the subsequent tenter stretching.

On the other hand, the white film of the present invention is preferably biaxially stretched to impart strength and stability to the film. Therefore, it is preferable to perform preheating at 110 to 140 ° C, which is higher than the stretching temperature in the machine direction. When the stretching temperature in the transverse direction is less than 110 ° C, the possibility of film breakage is high. , There is a problem that the thickness is poor and the physical properties are deteriorated.

Thereafter, d) heat-treating the stretched sheet at a temperature of 180 to 230 ° C in a tenter having five or more stages. If the heat treatment of the sheet is performed in five or more stages, it is advantageous in reducing the heat shrinkage rate when the film is used, and it is preferable to proceed in the 5-10 stages in consideration of productivity and ease of work.

In addition, after the step (d), the step (d) may further include loosening 10% or less, preferably 1.0 to 10.0%, of the length in the machine direction or the width direction. The stability of the physical properties of the film can be remarkably improved through the relaxation process. It is preferable that the relaxation is relaxed in the width direction. The relaxation also has the advantage of reducing the heat shrinkage during use of the film. If the relaxation rate exceeds 10.0%, the clip interval before the relaxation treatment is widened, and there arises a problem that the physical property irregularity of the clip holding portion and the non-flammable portion of the film becomes large.

e) heat-setting the relaxed or heat-treated sheet at 200 to 250 ° C to complete the white film of the present invention.

The white film prepared according to the method of the present invention may exhibit a crystallization rate of 60 to 300 seconds measured at 210 캜 isothermal conditions using the DSC. The crystallization rate in the above range is a factor to be exhibited by the amorphous polyester to be added to the present invention, thereby reducing the occurrence of breakage in the film production process and preventing excessive crystallization from occurring in the process of manufacturing a quenched unsupported sheet and pre- (Uniformity) of the white film in the lot can be improved. In the present invention, a white film having a thickness of 10 to 500 탆, a film opacity of 60 to 90%, and a gloss of 50 to 70% can be provided. When the thickness of the film is less than 10 mu m, the opacity is low and the physical properties may be deteriorated. When the thickness exceeds 500 mu m, the difficulty in manufacturing and the application of suitable use may be restricted.

The white film prepared as described above is excellent in opacity and gloss, has little breaking at the time of manufacture, and is excellent in workability.

In addition, the white film produced by the method of the present invention can be used for interior decorations, architectural displays, display necessities, displays, placards or labels, for use as advertising necessities or laminates in facilities outside shops or stores, Or as a beverage packaging material, and can be suitably used particularly for labeling and card printing.

As described above, the white film produced by the method of the present invention has no effect of breaking during the manufacturing process by using an inorganic material of controlled type, and is excellent in gloss, whiteness and opacity.

Further, there is an effect that a film having uniform properties can be obtained by controlling the stretching temperature, the stretching ratio, and the heat treatment temperature in the film production process.

Hereinafter, the present invention will be described in more detail with reference to the following examples.

Example 1

1) Manufacture of master batch

90 parts by weight of a polyethylene terephthalate resin having an intrinsic viscosity = 0.65 and 10 parts by weight of an amorphous polyethylene terephthalate copolymer (intrinsic viscosity = 0.70) containing 15 mol% of neopentyl glycol (NPG) A volume average particle diameter of 1.0 占 퐉, a distribution of 0.0001 to 0.3 占 퐉 in a volume of 3 vol%, a distribution of 3.0 to 10.0 占 퐉 in a volume of 2 volume%, a ratio of long diameter / short diameter of 0.9 and a refractive index of 1.64 Was put into a twin screw extruder hopper quantitatively to prepare a compounding chip.

2) Preparation of white film

36 parts by weight of the prepared master batch chip and 64 parts by weight of a polyethylene terephthalate chip having an intrinsic viscosity of 0.65 and no particles added at a polymerization stage were dried at 160 DEG C for 8 hours and then mixed. The moisture content of the dried chips was 100 ppm or less. The mixed chips were put in an extruder, melted and extruded from a T-die to produce a quenched sheet.

The sheet thus prepared was stretched 3.0 times in the machine direction (MD) at 105 ° C and then cooled to room temperature and then stretched 3.5 times in the width direction (TD) at 130 ° C, which is higher than the machine direction (MD) Treated at 220 deg. C in a heat treatment zone of a tenter in a tenter, and then the film was relaxed by 5% with respect to the length in the width direction at 210 DEG C and shrunk and cooled to prepare a biaxial oriented film having a thickness of 175 mu m.

Example 2

90 parts by weight of a polyethylene terephthalate resin having an intrinsic viscosity of 0.65 and 90 parts by weight of amorphous polyethylene terephthalate copolymerized with 15 mol% of isophthalic acid (IPA) in polymerization reaction of terephthalic acid (TPA) and ethylene glycol (EG) And 10 parts by weight of a resin (intrinsic viscosity = 0.70) were charged.

Comparative Example 1

Except that 70 parts by weight of a polyethylene terephthalate resin having an intrinsic viscosity of 0.65 and 30 parts by weight of an amorphous polyethylene terephthalate resin (intrinsic viscosity = 0.70) copolymerized with 15 mol% of NPG in the polymerization reaction of TPA and EG And the same procedure as in Example 1 was carried out.

Comparative Example 2

97 parts by weight of a polyethylene terephthalate resin having an intrinsic viscosity of 0.65 and 3 parts by weight of an amorphous poly (ethylene terephthalate) resin (intrinsic viscosity = 0.70) obtained by copolymerizing 15% by mole of NPG in the polymerization reaction of TPA and EG , The same procedure as in Example 1 was carried out.

* Test Methods

1) Intrinsic viscosity

And at a concentration of 0.3 g per 25 ml of ortho-chloropetol at 35 캜.

2) Measurement of average particle size and particle size distribution by circle equivalent

The average particle size and particle size distribution of the particles dispersed in ethylene glycol were measured using a Beckman particle size analyzer (Laser Diffraction Particle Size Analyzer (LS 13 320)).

3) Measurement of long diameter / short diameter

The long and short diameters of the particles were measured by a scanning electron microscope (SEM), taking a photograph of the particles and measuring them in a unit of 0.1 mu m through a scaler.

4) Measurement of fracture

During the stretching of the produced film or during the heat treatment, the film was broken in the process section and normal operation was impossible.

5) Measurement of opacity

Film was measured using an Opacity Meter Series 6000 instrument.

6) Measurement of gloss

Using a gloss meter (Model 4011) manufactured by Labotron, Germany, the measurement was carried out according to the ASTM D523 method at a measuring angle of 60 기준 with respect to black light.

7) Scanning electron microscope (SEM) measurement

Scanning electron microscope (SEM) was observed at a magnification of 1000 to 5000 times using a Jeol JSN 6700F instrument.

8) Isothermal crystallization rate differential scanning thermal analyzer (DSC) measurement

After heating to 280 ° C at a heating rate of 20 ° C / min using a differential scanning calorimeter (Perkin Elmer DSC 7), allow to stand for 5 minutes, then cool to 210 ° C and measure the crystallized peak while maintaining the temperature. The time to reach the peak is measured at the crystallization rate.

[Table 1]

As shown in Table 1, in Examples 1 and 2, a white film having satisfactory processability and satisfactory physical properties without breakage was produced. In Comparative Example 1, however, amorphous polyester resin was excessively The crystallization retardation was excessive, and no fracture occurred due to crystallization at the time of stretching, but void formation was so limited that the opacity was relatively insufficient. In the case of Comparative Example 2, too little amorphous polyester resin was added so that a sufficient crystallization retarding effect did not appear. As a result, unevenness in stretching and formation of large voids were high. As a result, .

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It will be obvious to the person.

Claims (11)

a) a master batch producing step comprising 5 to 25 parts by weight of amorphous polyester resin to 100 parts by weight of polyester resin and barium sulfate particles having a refractive index of 1.6 to 1.7; b) a sheet production step of extruding a mixture of the master batch and the polyester resin; c) stretching the prepared sheet; d) subjecting the stretched sheet to a heat treatment at 180 to 230 캜 in a tenter having five or more steps; And e) heat-setting the heat-treated sheet; ≪ / RTI > The method according to claim 1, Wherein the amorphous polyester resin is a copolymer of terephthalic acid and ethylene glycol in a polyethylene terephthalate structure in which isophthalic acid, oxyethoxybenzoic acid, adipic acid, sebacic acid, 5-sodium sulfoisophthalic acid, ester-forming derivatives thereof, An acid selected from the group consisting of mixtures; Propylene glycol, trimethylene glycol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, 1,4-bisoxyethoxybenzene, bisphenol, polyoxyethylene glycol, neopentylcyclole and mixtures thereof A diol component selected from the group consisting of: And 10 to 20 mol% of a component selected from the group consisting of a mixture thereof. The method according to claim 1, The barium sulfate has an average particle diameter of 1.0 to 1.5 탆 according to a circular shape and has no particle having a particle diameter of 0.0001 to 0.3 탆, no particle having a particle diameter of 3.0 to 10.0 탆 or less, or a particle size distribution of 5% And a ratio of long diameter / short diameter is 0.7 to 1.0. The method of claim 3, Wherein the barium sulfate in step a) is contained in an amount of 50 to 150 parts by weight based on 100 parts by weight of the polyester resin. The method according to claim 1, Wherein the polyester resin is polyethylene terephthalate. 6. The method of claim 5, Wherein the master batch is contained in an amount of 10 to 100 parts by weight based on 100 parts by weight of the polyethylene terephthalate resin. The method according to claim 1, The c) drawing step is a drawing step in which the sheet is stretched 2 to 4 times in the machine direction (MD) at 85 to 110 캜, cooled to 20 to 35 캜, stretched at 110 to 140 캜 in 3.0 to 4.0 times in the transverse direction (TD) Wherein the stretching is performed by a stretching method. The method according to claim 1, Further comprising a relaxation step of 10% or less after the heat treatment step. A white film produced by the method of any one of claims 1 to 8. 10. The method of claim 9, Wherein the white film has a crystallization rate of 60 to 300 seconds measured at 210 캜 isothermal conditions using DSC. delete