KR100601757B1 - Process for manufacturing Polytrimethyleneterephthalate films - Google Patents

Abstract

The present invention relates to a method for producing a polytrimethylene terephthalate biaxially stretched film, wherein the film is made of polytrimethylene terephthalate alone or mixed melt blended with a polyethylene terephthalate at the time of film formation. Method to adjust the method, heat setting section, relaxation rate, heat setting temperature increase value, etc., which solves the problem that the shrinkage occurs due to the large shrinkage stress during the stretching of the polytrimethylene terephthalate itself and the crystallization rate, so that the film is easily formed. Can be done.

Polytrimethylene Terephthalate * Elongation * Temperature * Elongation Ratio * Relaxation Rate * Thermal Fixed Section

Description

Process for manufacturing Polytrimethylene terephthalate biaxially oriented film

The present invention relates to a method for producing a polytrimethylene terephthalate biaxially oriented film, and more specifically, polytrimethylene terephthalate alone or a mixture of polyethylene terephthalate and melt blending to control the temperature and draw ratio of the stretching section to crystallization It relates to a method for producing a biaxially oriented film to delay and reduce the shrinkage stress to prevent breakage during the production of the film.

Polyethylene terephthalate (hereinafter referred to as PET) molded articles which are currently manufactured industrially are widely used in fibers, films and other molded articles. In particular, polyethylene terephthalate film obtained from aromatic dicarboxylic acid and glycol has mechanical properties such as heat resistance, tensile strength, elongation, Young's modulus, elastic recovery, impact resistance, dimensional stability, electrical insulation It is excellent and widely used for industrial and agricultural materials such as magnetic recording tape, photographic film, insulating material, film to be deposited. In addition, since the chemical properties, such as chemical resistance, weather resistance, water resistance, transparency, repellency, water resistance, gas barrier properties, etc. are excellent, the amount of use is also greatly increased as a packaging material for food or other items.

Recently, it has succeeded in industrially producing propylenediol in the shell chemical of the United States, and has succeeded in producing polytrimethylene terephthalate using it.

However, until now, the film has a large stretching stress and a high crystallization rate, so that it is difficult to manufacture a film, which is not an industrial application.

On the other hand, polytrimethylene terephthalate has a lot of problems in the manufacturing process when manufacturing a stretched film due to the fluidity of the polymer chain compared to polyethylene terephthalate, in particular, the shrinkage stress during stretching is very large, the crystallization speed is fast stretching The fracture occurs well, and the fracture occurs well because the shrinkage stress is large in the heat treatment process.

Thus, the present inventors melt blended polytrimethylene terephthalate alone or a mixture with polyethylene terephthalate to produce a biaxially stretched film, in which the temperature and the draw ratio of the stretching section is adjusted, the shrinkage stress during stretching is small, crystallization rate It was found to be able to prevent the occurrence of breaks during stretching to lower the completed the present invention.

Accordingly, it is an object of the present invention to provide a method for producing a biaxially stretched film which is capable of preventing the occurrence of breakage during manufacturing into a film due to a low shrinkage stress upon stretching and a slow crystallization rate.

The biaxially oriented film production method of the present invention for achieving the above object is drawn in the temperature range of 30 ~ 80 ℃ by melt blending polytrimethylene terephthalate alone or a mixture of polyethylene terephthalate, the draw ratio of MD and TD It is characterized by performing so that 2 to 5 times respectively.

The present invention will be described in more detail as follows.

The biaxially oriented film of the present invention is obtained by melt blending polytrimethylene terephthalate alone or a mixture with polyethylene terephthalate.

Polytrimethylene terephthalate is produced by polycondensation of propylene glycol with dicarboxylic acid such as terephthalic acid, and the main characteristics thereof are shown in Table 1 below when compared with polyethylene terephthalate and nylon 6.

Polytrimethylene terephthalate Polyethylene terephthalate Nylon 6 Tm (℃) 226.6 253.7 223.1 Tmc (℃) 167.7 170-180 160 Tcc (℃) 74.1 132.2 69.0 Tg (℃) 43.4 75.8 42.5 Crystallization rate (sec) 166.1 (190 ℃) 211.6 (210 ℃) 70.1 (190 ℃) Density (g / cm 3) 1.33 1.40 1.13 Water absorption rate (%) 0.15 0.49 9.5 Stress resistance excellent excellent low Shrinkage, 100 ℃ (%) 13.8 2.4 0.5

As can be seen in Table 1, the polytrimethylene terephthalate has a faster crystallization rate when drawn compared to polyethylene terephthalate due to the low glass transition temperature and density.

In general, a stretching section for producing a polymer biaxially oriented film is performed between Tg and Tcc. Polytrimethylene terephthalate has a stretching section about 30 ° C narrower than that of the same polyester-based polyethylene terephthalate. It has the property of rapid crystallization. In addition, the stress during the stretching is very large, the shrinkage rate is large, there are many problems in industrial use. Therefore, it is necessary to apply a sequential biaxially oriented film manufacturing conditions different from the conventional polyethylene terephthalate.

Specifically, first, the polymer used in the preparation is polytrimethylene terephthalate alone or a mixture with polyethylene terephthalate, and the mixing amount of the polyethylene terephthalate when mixing is preferably within 40% by weight.

In manufacturing a film from such a molten blend of a polymer, the temperature of the new section is preferably 30 to 80 ° C. This is between the glass transition temperature and the elevated crystallization temperature of the melt blend used.

First, the MD stretching temperature is preferably 30 to 60 ° C., which is Tcc or more of polytrimethylene terephthalate, and at the time of TD stretching, the temperature is preferably 10 to 20 ° C. higher than the MD stretching temperature. And breakage occurs.

In the draw ratio, both MD and TD are 2 to 5 times, preferably 3.0 to 4.0 times. Since the draw ratio affects the mechanical properties of the final film, drawing at least twice as much as MD and TD is required.

In addition, the relaxation rate should be 8% or more, specifically 8-20%, because the elastic recovery rate is very large among the basic properties of the polytrimethylene terephthalate. In addition, when blended with polytrimethylene terephthalate and other polyester-based polymers, the shrinkage rate is increased, so a relaxation of 8% or more is required.

On the other hand, in the stretching method, one-stage stretching is preferable. In particular, in the case of sequential biaxial stretching, the one-stage stretching method is advantageous because there is little neck-in after MD stretching.
When extending | stretching, TD extending | stretching temperature is set to the temperature below melting | fusing point of polytrimethylene terephthalate, and it carries out biaxial stretching sequentially.

In the heat treatment process during sequential stretching, the TD heat setting inlet temperature is preferably 150 ° C. or lower, preferably 120 to 150 ° C., which is broken by the shrinkage stress of the film when the heat setting is suddenly increased after stretching. This is because the occurrence increases.

And when the number of heat setting sections (number of tenters) is small, since the heat setting heat quantity is insufficient and shrinkage arises large in the film which is a final product, it is preferable that it is at least 3 or more.

Hereinafter, an example in which the biaxially stretched film is manufactured by adjusting MD, TD stretching temperature, MD, TD stretching ratio, stretching method, heat setting section, relaxation rate, and heat setting temperature increase value during stretching will be described in detail. As such, the present invention is not limited by the examples.

Examples 1-3 and Comparative Examples 1-4

Polytrimethylene terephthalate alone or mixed melt blended polytrimethylene terephthalate and polyethylene terephthalate to prepare a biaxially stretched film under the film forming conditions as shown in Table 2 below.

Specifically, as shown in Table 2, the polytrimethylene terephthalate and the blend polymer melt-extruded at a temperature above the melting point with a polymethylene terephthalate film are quenched to a temperature below the glass transition temperature, and the film is biaxially stretched again. Got it.

Detailed film forming conditions are as shown in Table 2 below.

Example Comparative example One 2 3 One 2 3 4 Article Conditions Composition (PTT / PET) 100/0 100/0 85/15 100/0 0/100 100/0 100/0 Extrusion Temperature (℃) 260 260 280 260 280 260 260 Stretching temperature (℃) MD 30-50 30 to 60 40-50 50-70 80-90 30-50 30-50 TD 45 to 60 50-70 50 to 60 70-90 100-120 50 to 60 45 to 60 Draw ratio MD 3.5 3.5 3.8 3.5 3.8 3.5 3.5 TD 3.5 3.5 3.8 3.5 3.8 3.5 3.5 Relaxation rate (%) 12 15 15 15 7 7 12 MD drawing method 1 stage drawing 1 stage extension 1 stage extension 3-stage extension 3-stage extension 2-stage extension 1 stage extension TD heat setting temperature (℃) 200 200 200 200 220 210 200 Heat setting inlet temperature (℃) 120 150 120 150 200 200 150 The number of fixed intervals 5 5 5 5 5 5 2

In the above examples and comparative examples, the extrusion temperature was prepared at the processing temperature above the melting point of the polymer used, and the stretching section was compared to limit the temperature section of about 30 to 120 ℃.

First, it can be seen that the stretching section is suitable between the glass transition temperature and the elevated crystallization temperature as in Examples 1 to 3.

On the other hand, in the case of Comparative Example 1, the fracture occurred because the temperature at the time of TD stretching is higher than the glass transition temperature, and it can be seen that the temperature of the stretching section can directly affect the fracture.

In the case of the draw ratio, it is understood that the ratio of MD and TD is 3.0 to 4.0 times. Since the draw ratio affects the mechanical properties of the final film, drawing at least twice as much as MD and TD is required.

The relaxation rate should be more than 8% because the elastic recovery rate is very high among the basic properties of polytrimethylene terephthalate. In addition, when blended with polytrimethylene terephthalate and other polyester-based polymers, the shrinkage rate is increased, so a relaxation of 8% or more is required.

On the other hand, in the MD stretching method, in the case of comparing single-stage stretching and multi-stage stretching, the stretching method does not have a big problem in manufacturing the film, but in case of successive biaxial stretching, the single-stage stretching method has less neck-in after MD stretching. Therefore, it can be seen that it is advantageous.

On the other hand, the TD heat setting inlet temperature in the heat treatment process during successive stretching is suitable to the temperature of 150 ℃ or less, which is suddenly increased after the stretching is broken by the shrinkage stress of the film during heat setting as in Comparative Example 3 This is because the occurrence increases. And, as in Comparative Example 4, if the number of heat setting sections (number of tenters) is small, there is a problem that heat shrinkage heat is insufficient and shrinkage greatly occurs.

In the case of Comparative Example 2, a polyethylene terephthalate biaxially oriented film is shown.

Tensile strength, hot air shrinkage rate, heat shrinkage rate, and neck-in measurement results according to the above film forming conditions are shown in Table 3 below.

Here, the measuring method of each physical property is as follows.

(1) Tensile strength: Test according to ASTM D-882 (Model name: Instron 1123, Measuring conditions-Drawing speed 300mm / min, Distance between grips 100nn, Temperature 20 ℃, Relative humidity 65%, Specimen size-Width 10mm, Length 100mm)

(2) Hot air shrinkage rate / hot shrinkage rate

Hot air shrinkage measurement condition: Measurement condition-Measurement of dimensional change after 10 minutes free field heat treatment

Heat shrinkage measurement condition: Measurement of dimensional change after standing at 100 ℃ for 30 minutes in a hot water

Specimen size-20 × 20cm in length and width

Heat Shrinkage Rate / Hot Air Shrinkage Rate (%) = Strain Length / Initial Length × 100

(3) neck-in measurement: measurement of dimensional change of quench sheet before and after MD stretching

neck-in degree (5) = deformation length / initial length × 100

Tensile Properties (MD / TD) Shrinkage (%) Breakage neck-in degree (%) burglar Shinto Heat shrink Hot air contraction Example One 26.3 / 23.5 135.6 / 120.5 2.75 / 0.25 3.75 / 0.75 radish 8 2 26.8 / 24.6 120.5 / 111.5 1.75 / 0.20 2.35 / 0.50 radish 8 3 26.3 / 24.9 138.5 / 131.5 2.35 / 0.45 2.95 / 0.50 radish 8 Comparative example One - - - - Breaking 18 2 29.6 / 27.5 134.3 / 127.7 1.75 / 0.75 2.50 / 1.25 radish 18 3 - - - - Breaking 16 4 25.1 / 22.2 154.2 / 136.7 4.60 / 3.85 5.60 / 4.35 radish 8

As described in detail above, the MD, TD stretching temperature and draw ratio, stretching method, heat setting section, relaxation when stretching the film into a film of polytrimethylene terephthalate alone or mixed melt blended with polyethylene terephthalate according to the present invention When the rate, heat setting temperature increase value, and the like are adjusted, the shrinkage stress during the stretching of the polytrimethylene terephthalate itself is high, and the crystallization rate is fast, thereby solving the problem of breaking, thereby making it easier to form the film. .                     

Claims (6)

The polytrimethylene terephthalate alone or a mixture of polyethylene terephthalate and melt blended to draw at a temperature range of 30 ~ 80 ℃, the temperature of the heat setting inlet is 120 ~ 150 ℃ during TD stretching, the number of heat setting section during stretching 3 or more, a method for producing a biaxially stretched film by performing a draw ratio of MD and TD 2 to 5 times, respectively. The method for producing a biaxially stretched film according to claim 1, wherein a relaxation rate is provided at 8 to 20% during stretching. The method for producing a biaxially oriented film according to claim 1, wherein the MD stretching is performed by a one-stage stretching method. 2. The method for producing a biaxially oriented film according to claim 1, wherein the stretching is set at a temperature below the melting point of the polytrimethylene terephthalate and the biaxially oriented stretching is performed. delete delete