KR100269872B1 - Polytrimethyleneterephthalate film of manufacturing method - Google Patents

Abstract

PURPOSE: A method for preparing biaxially oriented polytrimethylene terephthalate film is provide for accomplishing high break strength, heat-shrinkage rate and dimensional stability by dispersing at least one of active materials selected from calcium carbonate, silica and alumina in PTT resins having ultimate viscosity of 1.0-1.25. CONSTITUTION: The method for preparing biaxially oriented polytrimethylene terephthalate film comprises; the first step of extrusion-forming the mixture dispersed with at least one active material such as calcium carbonate, silica and alumina in PTT resin to form molten sheet; the second step of preparing un-oriented sheet by cooling and solidifying the molten sheet; the third step of longitudinally drawing the unoriented sheet at 15-20 deg.C. on the drawing roll; the fourth step of transversally drawing the elongated sheet from the third step by a tender at 50-85deg.C; the fifth step of heat-fixing the drawn sheet from the fourth step at 120-200 deg.C; and the sixth step of cooling the fixed film to 25-40 deg.C.

Description

Polytrimethyleneterephthalate film of manufacturing method

The present invention relates to a biaxially oriented polytrimethylene terephthalate film and a method for manufacturing the same, and more particularly, to excellent magnetic properties such as elastic modulus, stiffness, tensile strength, or the like, or by barrier coating, aluminum deposition, etc. The present invention relates to a biaxially orientated polytrimethylene terephthalate film which can be used for a wide range of applications, for packaging, packaging, and the like, and a method of manufacturing the same.

Polytrimethylene terephthalate (henceforth PTT) resin is resin obtained by polycondensation by the direct esterification method of 1, 3- propanediol and terephthalic acid, or the transesterification method of 1,3 propanediol and dimethyl terephthalate. The PTT resin is composed of polyethylene terephthalate (hereinafter referred to as PET) in which the aliphatic portion of the main chain is made of trimethylene and dimethylene, and polybutylene terephthalate (hereinafter referred to as PBT) in which the aliphatic portion is tetramethylene. It is a crystalline polyester resin which has a molecular structure between.

As a plastic material, PTT resin has suitable properties for use in fibers, films, plastic containers, engineering plastics, etc., and exhibits intermediate characteristics of PET resin or PBT resin except for the lowest melting point. In other words, PTT resin combines the strength, stiffness, and impact strength of PET resin with molding properties such as low melting temperature, low molding temperature, and fast crystallization rate of PBT resin, and dimensional stability, which is the basic characteristic of aromatic polyester resin. It is a resin excellent in electrical insulation and chemical resistance. In addition, according to the experimental results of the present inventors, the PTT film has excellent abrasion resistance and toughness like a nylon resin, and excellent mechanical properties, chemical resistance, and electrical properties, such as PET.

The PET resin, the PTT resin, and the PBT resin are all structurally similar aromatic polyester resins, but due to the difference in the number of methyl groups included in the repeating unit of the molecular chain, the difference in physical properties and processing characteristics is very severe. In particular, since the difference in crystallization characteristics affecting the molding process of the crystalline resin and the properties of the molded article is very large, there is a difference in each molding method and use. Since PET resin has the lowest crystallization rate among the three resins, it is easy to manufacture fibers, films, sheets or transparent containers by melt spinning, melt extrusion, or blow molding rather than injection molding. Since PBT resin has a very fast crystallization rate, it is very difficult to form a film by sequential biaxial stretching like PET resin, but in injection molding, it is possible to shorten the production cycle and to have excellent physical properties of the injection molded article.

On the other hand, the PTT resin has an intermediate crystallization rate than the two resins, but the crystallization behavior is very specific. In particular, the amorphous sheet of the PTT resin is very difficult to draw because the crystallization proceeds more rapidly than the PBT resin at a temperature above the crystallization temperature.

Therefore, in manufacturing a sequential biaxially stretched PTT film, the biaxially-oriented PTT film which was excellent in the film characteristic was not able to be obtained by the manufacturing process of the conventional polyester film.

Accordingly, the technical problem to be achieved by the present invention is to provide a biaxially oriented PTT film having excellent film properties in order to solve the above-mentioned conventional problems.

Another object of the present invention is to provide a method for producing a biaxially oriented PTT film having excellent film properties.

In order to achieve the above technical problem, the present invention is a biaxially oriented PTT characterized in that by dispersing at least one lubricant selected from the group consisting of calcium carbonate, silica and alumina in PTT resin having an extreme viscosity of 1.0 ~ 1.25 Provide a film.

In order to achieve the above another technical problem, the present invention provides a mixture comprising (a) a mixture containing at least one lubricant selected from the group consisting of calcium carbonate, silica and alumina in a PTT resin having an intrinsic viscosity of 0.95 to 1.30 dl / g. Manufacturing an melt sheet by extrusion molding; (b) cooling and solidifying the molten sheet to prepare an unstretched sheet; (c) stretching the unoriented sheet in a longitudinal direction on a stretching roll maintaining a temperature range of 15 to 20 ° C. using hot air in a temperature range of 45 to 75 ° C .; (d) stretching the longitudinally stretched film in a transverse direction using a tenter in a temperature range of 50 to 85 ° C .; (e) heat setting the stretched film in the longitudinal and transverse directions at a temperature in the range of 120 to 200 ° C; And (f) it provides a method for producing a biaxially oriented PTT film comprising the step of cooling the heat-set film to a temperature range of 25 ~ 40 ℃.

The biaxially oriented PTT film according to the present invention has good breaking strength, thermal shrinkage rate and dimensional stability.

Hereinafter, the biaxially oriented PTT film according to the present invention will be described in detail.

In the present invention, the PTT resin can be produced by any of the transesterification method and the direct polymerization method, and any of batch and continuous processes can be employed in the process configuration. PTT is prepared in two steps. That is, in the case of using the direct ester method, 1,3-propanediol and terephthalic acid are esterified to synthesize bis-γ-hydroxytrimethylene terephthalate (BHTT) and low molecular weight condensates of BHTT. -PTT is obtained by increasing the length of the molecular chain by melting and condensation polymerization while removing propanediol. In the case of using the transesterification method, low molecular weight condensates of bis-γ-hydroxytrimethylene terephthalate (BHTT) and BHTT are synthesized by transesterifying 1,3-propanediol and dimethyl terephthalate. PTT is obtained by increasing the length of the molecular chain by melting and condensation polymerization while removing 3-propanediol.

In the case of using the transesterification method, there is no particular limitation on the transesterification catalyst, and any one can be used as long as it is known to prepare a conventional PET resin. For example, alkali earth metal compounds such as titanium compounds, magnesium compounds, zirconium compounds, sodium compounds, potassium compounds, calcium compounds, barium compounds, and cobalt compounds, zinc compounds, and manganese compounds may be used that are soluble in the reaction system.

The polymerization catalyst is also not limited, but it is preferable to use an appropriately selected from antimony compounds, germanium compounds, and titanium compounds.

The PTT resin used in the present invention preferably has an intrinsic viscosity measured by dissolving 0.3 g of PTT resin in 25 ml of? -Chlorophenol at 35 ° C in the range of 0.95 to 1.30 dl / g. If the intrinsic viscosity of the PTT resin is less than 0.95 dl / g, breakage occurs frequently during stretching, which greatly lowers the productivity and decreases physical properties such as mechanical strength of the final film. In addition, when the intrinsic viscosity of the PTT resin exceeds 1.30 dl / g, the melt viscosity increases so much that the shear stress increases, thereby making the extrusion process unstable. This is also undesirable since the production cost rises as necessary.

Biaxially oriented PTT film according to the present invention, in order to lower the coefficient of friction of the film to facilitate the winding process or to impart the required function according to the application, a suitable amount of a lubricant such as calcium carbonate, silica, alumina, etc. in the PTT resin It is preferable to disperse | distribute and to form an unevenness | corrugation on the surface of a film. The average particle diameter of the lubricant is preferably 0.1 to 10㎛, the content is preferably 0.1 to 10% by weight based on the weight of the PTT resin. If the size of the particles is less than 0.1㎛ the effect on the surface properties of the film is insignificant, if it exceeds 10㎛ the surface roughness of the film is excessively increased to give a rough feeling. In addition, when the addition amount is less than 0.1% by weight, the effect of addition is insignificant, and when the addition amount is more than 10% by weight, surface characteristics are deteriorated and pressure increase is accelerated due to clogging of the filter during the film manufacturing process, resulting in deterioration of filter life and production efficiency This deteriorates, the dispersibility worsens, the breakage increases, and there is a problem in weight reduction.

Next, the sequential biaxial stretching method which is the core of the method for producing a PTT film according to the present invention will be described in detail.

First, a melt sheet is prepared by extrusion molding a mixture containing at least one lubricant selected from the group consisting of calcium carbonate, silica and alumina in PTT resin having an intrinsic viscosity of 0.95 to 1.30 dl / g. Subsequently, after cooling and solidifying the molten sheet to prepare an unstretched sheet, the unstretched sheet is heated to a temperature of 15 to 20 ° C. using hot air in a temperature range of 45 to 75 ° C., more preferably 55 to 65 ° C. The drawing is carried out in the longitudinal direction in the drawing roll maintaining the range. Herein, when the temperature of the hot air during the longitudinal stretching is less than 45 ° C., the stretching stress is too large and stretching is difficult. When the temperature of the hot air exceeds 75 ° C., the sheet crystallizes and stretching is impossible.

Subsequently, the longitudinally stretched film is stretched in the transverse direction using a tenter in a temperature range of 50 to 85 ° C, more preferably 60 to 75 ° C. At this time, if the stretching temperature in the transverse direction is less than 50 ℃ stretching stress is too large, the stretching is difficult, if the stretching temperature exceeds 85 ℃ crystallinity is high, the stretching is impossible or breakage occurs during stretching is undesirable.

Subsequently, the film stretched in the longitudinal and transverse directions is subjected to heat setting in a temperature range of 120 to 200 ° C, more preferably 140 to 180 ° C. At this time, if the heat setting temperature is less than 120 ℃ heat setting effect is not obtained, even if the heat setting temperature exceeds 200 ℃ it is not preferable because the mechanical properties and dimensional stability is no longer improved. Finally, the heat-set film is cooled to a temperature range of 25 ~ 40 ℃. If the heat setting is not performed, the shrinkage of the film is large and the final roll state is poor. At this time, if the cooling temperature exceeds 40 ℃ is not preferable because the cooling effect is insufficient, in order to be less than 25 ℃ requires an additional cooling equipment and can not expect a better effect.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the scope of the present invention is not limited to the following Examples.

In Examples and Comparative Examples of the present invention, various physical property evaluation of the prepared PTT film was performed by the following method.

(1) longitudinal breaking strength

The UTM 4206 of Instron of the United States was used to prepare a specimen having a width of 15 mm and a length of 50 m, and then measured the breaking strength of the pitch at a speed of 20 mm / min.

(2) longitudinal heat shrinkage

Specimens of 10 mm in width and 200 mm in length were measured after being left in a hot air oven at 150 ° C. for 30 minutes. At this time, the heat shrinkage was calculated as follows.

(3) Film condition and film characteristics

After winding up a film in roll state, when a wrinkle exists in the circumferential direction on the roll surface, it was judged that it was defect and it was favorable if there was no wrinkle. In addition, it was determined that the film properties were poor when the thermal shrinkage was 3.0% or more or the longitudinal breaking strength was 20 kg / mm ² or less.

Example 1

PTT polycondensation reactor, which can be stirred at about 200 rpm and is equipped with a transesterification reactor equipped with a separation column for separating 1,3-propanediol and methanol from the reaction effluent, and an inverter type stirrer capable of stirring at about 10 to 50 rpm. And a reactor having a condenser for condensing the effluent and a polymerization reactor equipped with a vacuum pump were used.

First, 800 parts by weight of dimethyl terephthalate and 595 parts by weight of 1,3-propanediol were added to a transesterification reactor, and when the reactant reached about 150 ° C, 0.05 wt% of tributylene titanate was added as a catalyst and 120 The temperature was gradually raised over minutes to terminate the transesterification reaction at 220 ° C. After the transesterification reaction, trimethyl phosphate was added as a stabilizer. At this time, 0.02 parts by weight of silica having an average particle diameter of 2.5 μm was added 5 minutes before the stabilizer was added during the transesterification reaction. Subsequently, after about 15 minutes, antimonirea acetate was added as a polymerization catalyst, and it heated up again to 250 degreeC.

The low molecular weight condensate of BHTT and BHTT thus obtained was dropped into the polymerization reactor while pressurizing nitrogen. Then, polymerization is performed for about 2 hours at a pressure of about 1.0 mmHg and a temperature of about 265 ° C. When the power consumption of the stirrer motor reaches a constant value, the polymerization reaction is stopped to obtain a PTT resin having an intrinsic viscosity of 1.16 ㎗ / g. Got it. It was then pelletized. At this time, the ultimate viscosity was obtained by adding PTT resin into ο-chlorophenol and dissolving the PTT resin at 100 ° C., and then varying the concentration using a Uberod viscosity tube at 35 ° C., and then extrapolating to infinite lean concentration. .

Subsequently, the PTT pellet was dried at 150 ° C. under vacuum for about 5 hours, and then melt-extruded at a temperature of 275 to 290 ° C. to quench on a quench roll having a surface temperature of about 15 ° C. to obtain an amorphous unstretched sheet. Subsequently, the unstretched sheet was stretched in the longitudinal direction using 2.5 times hot air at 51 ° C, and then stretched 1.5 times in the transverse direction using a tenter at 63 ° C. Subsequently, the film stretched in the longitudinal and transverse directions was heat set at 150 ° C., and the heat set film was cooled to 25 ° C. to complete the production of the biaxially oriented PTT film.

The stretch and film properties of the PTT film thus prepared were evaluated and shown in Table 1, which showed good film properties due to high longitudinal breaking strength and low longitudinal heat shrinkage. This is considered to be because the orientation of the PTT molecules was sufficiently caused by stretching and the crystallinity of the film was increased through sufficient heat treatment.

Examples 2-5

A biaxially oriented PTT film was prepared in the same manner as described in Example 1 under the stretching and heat treatment conditions described in Table 1. The stretch and film properties of the PTT film thus prepared were evaluated and shown in Table 1, which showed good film properties due to high longitudinal breaking strength and low longitudinal heat shrinkage.

Comparative Example 1

The longitudinal stretching was performed only by hot air at 42 ° C. using the PTT resin obtained in Example 1, but at the stretching temperature, a sufficient amount of heat was not supplied to the unstretched sheet, and thus the stretching stress was very large.

Comparative Example 2

Using the PTT resin obtained in Example 1 was stretched 2.5 times in the longitudinal direction with a hot air at 48 ℃, and stretched 1.5 times in the transverse direction in a tenter maintained at 44 ℃, the species at the transverse stretching temperature Due to insufficient heat supply to the sheet stretched in the direction, the stretching stress was very large, so stretching in the transverse direction was impossible.

Comparative Example 3

The PTT resin obtained in Example 1 was used to stretch 2.5 times in the longitudinal direction with hot air at 63 ° C., and 1.5 times in the transverse direction in a tenter maintained at 55 ° C. The PTT film was then heat set at 102 ° C. As shown in Table 1, the drawing characteristics were good, but the longitudinal breaking strength was low, and the longitudinal thermal contraction rate was high. This is considered to be because the heat setting temperature is not high enough and the crystallinity of the film is insufficient.

Comparative Example 4

Using the PTT resin obtained in Example 1, longitudinal stretching was carried out only by hot air at 78 ° C., but the stretching temperature was too high as shown in Table 1, and thus stretching was not possible because the unstretched sheet was crystallized before stretching.

Longitudinal orientation Lateral stretching Heat setting temperature (℃) Longitudinal breaking strength (kg / mm ² ) Longitudinal heat shrinkage (150 ℃ × 30 minutes) Remarks Temperature (℃) Elongation ratio Stretching characteristics Temperature (℃) Elongation ratio Stretching characteristics Example 1 51 2.5 Yeonsin Yang 53 1.5 Yeonsin Yang 150 22.4 2.9 △ Example 2 71 2.5 Yeonsin Yang 76 1.5 Yeonsin Yang 176 23.9 1.7 ○ Example 3 69 2.5 Yeonsin Yang 84 1.5 Yeonsin Yang 201 23.7 2.1 ○ Example 4 64 2.5 Yeonsin Yang 81 1.5 Yeonsin Yang 122 24.5 4.1 △ Example 5 63 2.5 Yeonsin Yang 75 1.5 Yeonsin Yang 131 21.5 3.7 △ Comparative Example 1 42 - Not Stretchable ^# - - - - - - × Comparative Example 2 48 2.5 Yeonsin Yang 44 1.5 Not Stretchable ^# - - - × Comparative Example 3 63 2.5 Yeonsin Yang 55 1.5 Yeonsin Yang 102 20.8 5.4 △ Comparative Example 4 78 - Not Stretchable ^## - - - - - - ×

#: Not possible to stretch due to stretch stress ##: Not possible to stretch due to crystallization

X: film condition and film property defect △: film condition good and film characteristic defect

○: Good film condition and film characteristics

As described above, the biaxially oriented PTT film according to the present invention has good breaking strength, thermal contraction rate and dimensional stability, and thus may be used for packaging, electrical insulation, magnetic recording media, and the like.

Claims (1)

(a) extrusion molding a mixture containing at least one lubricant selected from the group consisting of calcium carbonate, silica and alumina in polytrimethylene terephthalate resin having an intrinsic viscosity of 0.95 to 1.30 dl / g to produce a molten sheet step; (b) cooling and solidifying the molten sheet to prepare an unstretched sheet; (c) stretching the unoriented sheet in a longitudinal direction on a stretching roll maintaining a temperature range of 15 to 20 ° C. using hot air in a temperature range of 45 to 75 ° C .; (d) stretching the longitudinally stretched film in a transverse direction using a tenter in a temperature range of 50 to 85 ° C .; (e) heat setting the stretched film in the longitudinal and transverse directions at a temperature in the range of 120 to 200 ° C; And (F) a method for producing a biaxially oriented polytrimethylene terephthalate film comprising the step of cooling the heat-set film to a temperature range of 25 ~ 40 ℃.