TWI595022B - Polyester films and methods for manufacturing the same - Google Patents

Description

Polyester film and preparation method thereof

The present invention relates to a polyester film and a process for the preparation thereof.

Polyester film can be used in a variety of different applications, in order to meet the different use environments, there are different requirements for the functional properties of polyester materials. For example, the back-sheet of the solar cell film group is made of DuPont's tedlar film as the upper and lower layers, and a polyester film is used in the middle. Since the solar cell membrane group is often in a high temperature or high humidity environment, there is an increasing demand for weather resistance of materials. Therefore, the polyester film in the existing back-sheet needs to have good weather resistance, including heat resistance and hydrolysis resistance.

Based on the above, the development of a polyester film having both good heat resistance and hydrolysis resistance is an important subject.

One embodiment of the present invention provides a polyester film which is a reaction product of a composition. The composition consists essentially of terephthalic acid monomer, ethylene glycol monomer and branched monomer, and the branched monomer has the formula (I), formula ( II), or the structure shown in formula (III),

Wherein, X is independently a hydroxyl group, a carboxyl group, or a -COOR; R is a C _1-6 alkyl group; the terephthalic acid monomer and the ethylene glycol monomer have a molar ratio of about 50:50 to 30:70. And, the addition ratio of the branched monomer is between about 1 mol% and 3 mol%, based on the total number of moles of the terephthalic acid monomer and the ethylene glycol monomer.

Another embodiment of the present invention provides a method for preparing a polyester film, comprising reacting a branched monomer with a mixture, wherein the mixture is composed of terephthalic acid monomer and ethylene glycol. a body composition in which the branch monomer has a structure represented by formula (I), formula (II), or formula (III)

Wherein, X is independently a hydroxyl group, a carboxyl group, or a -COOR; R is a C _1-6 alkyl group; the addition ratio of the branched monomer is between about 1 mol% and 3 mol%, and the terephthalic acid monomer and The molar total of ethylene glycol monomers is based on the total.

The above and other objects, features, and advantages of the present invention will become more apparent and understood.

Fig. 1 is a modified polyester ester granule of Examples 1 to 3 and Comparative Examples 1 to 3 of the present invention. Resistance to hydrolysis test results.

Fig. 2 is a hydrolysis resistance test result of the modified polyester ester particles of Examples 4 to 6, Comparative Example 1 and Comparative Example 4 of the present invention.

Fig. 3 is a graph showing the hydrolysis resistance test results of the modified polyester ester particles of Examples 7 to 9 and Comparative Example 1 of the present invention.

Fig. 4 is a thermomechanical analysis test result of the polyester films of Examples 4 to 6, Comparative Example 1 and Comparative Example 4 of the present invention.

Fig. 5 is a graph showing the dimensional stability test results of the polyester films of Examples 5 to 6, Comparative Example 1 and Comparative Example 4 of the present invention. And Fig. 6 shows the hydrolysis resistance test results of the polyester films of Examples 4 to 6, Comparative Example 1 and Comparative Example 4 of the present invention.

The polyester film provided by the present invention is a reaction product of a composition, and the composition is substantially composed of the following monomers: terephthalic acid (TPA) monomer, ethylene glycol (EG) single And a branched monomer having a structure represented by formula (I), formula (II), or formula (III),

Wherein X is independently a hydroxyl group, a carboxyl group, or a -COOR, and R is a _C1-6 alkyl group.

In one embodiment, terephthalic acid monomer and ethylene glycol monomer Mobbi is between 50:50 and 30:70.

In another embodiment, the addition ratio of the branched monomer is between about 1 mol% and 3 mol% based on the total number of moles of the terephthalic acid monomer and the ethylene glycol monomer. In still another embodiment, the addition ratio of the branched monomer is between about 1.5 mol% and 3 mol%, based on the total number of moles of the terephthalic acid monomer and the ethylene glycol monomer.

The term "between a certain two values" as used in the present invention includes the above two numerical values. For example, the addition ratio of the branched chain monomer is between about 1 mol% and 3 mol%, which means the addition ratio of the branched monomer. The range includes 1 mol% and 3 mol%.

If the content of the branched monomer is too low, the hydrolysis resistance of the composition is lowered. If the content of the branched monomer is too high, the heat resistance of the composition is lowered. The addition of branched monomer can promote the esterification and condensation reaction of terephthalic acid monomer and ethylene glycol monomer, reduce the production of terminal acid groups, reduce the formation of oligomers, inhibit the hydrolysis of materials, and also limit the high The movement of the molecular chain during heating increases the dimensional stability of the membrane.

According to an embodiment of the present invention, the composition is subjected to esterification polymerization at 250 ° C to 280 ° C (the reaction is carried out by mixing a terephthalic acid monomer, an ethylene glycol monomer, and a branched monomer), and is cut. The first modified polyester ester granules are obtained from the granules. In one embodiment, the ratio of the first modified polyester ester particles to oligomers is less than about 1.2 wt%, such as between about 0.6 wt% and 1.2 wt%. In one embodiment, a first acid value of the modified polyester pellets is less than equal to about 33eq / 10 ⁶ g, for example between about 5eq / 10 ⁶ g to 33eq / 10 ⁶ g, or of about 10 eq / 10 ⁶ g to 25 eq/10 ⁶ g. According to an embodiment of the invention, the glass transition temperature (Tg) of the first modified polyester ester particles is between about 77 ° C and 100 ° C, for example between about 77 ° C and 90 ° C. According to another embodiment of the present invention, the intrinsic viscosity (IV) of the first modified polyester ester particles is between about 0.11 nη _r /C and 0.91 nη _r /C or about 0.51 nη _r /C. Between 0.71nη _r /C.

According to another embodiment of the present invention, the terephthalic acid monomer and the ethylene glycol monomer in the above composition are first subjected to esterification polymerization, wherein the molar ratio of the terephthalic acid monomer and the ethylene glycol monomer (mole ratio) is about 1:1.2 to 1:1.4, the reaction temperature is between 250 ° C and 280 ° C, and the polymerization time is between about 1 and 3 hours to obtain polyethylene terephthalate. A polyethylene terephthalate (PET) is further added to the branched monomer to undergo a modification reaction between 260 ° C and 300 ° C, and the second modified polyester ester granule is obtained by dicing. In one embodiment, the ratio of the second modified polyester ester particles to oligomers is less than about 1.2 wt%, such as between about 0.6 wt% and 1.2 wt%. The second acid value of the modified polyester pellets is less than equal to about 33eq / 10 ⁶ g, for example between about 5eq / 10 ⁶ g to 33eq / 10 ⁶ g, or of about 10eq / 10 ⁶ g to 25eq / Between 10 ⁶ g. According to an embodiment of the invention, the second modified polyester ester granule has a glass transition temperature (Tg) of between about 77 ° C and 100 ° C, for example between about 77 ° C and 90 ° C. According to another embodiment of the present invention, the intrinsic viscosity (IV) of the second modified polyester ester particles is between about 0.11 nη _r /C and 0.91 nη _r /C or about 0.51 nη _r /C. Between 0.71nη _r /C.

According to an embodiment of the invention, the first modified polyester ester particles or the second modified polyester ester particles may be further formed into a thin plate by a melt extrusion process. According to another embodiment of the present invention, the melt extrusion process can be carried out by using a continuous extruder (for example, a twin-screw extruder or a co-extrusion extruder), and the process temperature is about 200 ° C to 350 ° C or 250 ° C. Between 330 ° C, the above twin screw extrusion The speed of the machine is between about 50 rpm and 300 rpm, and finally melted out through the T-die, and a thin plate of uniform thickness is obtained through the casting drum. The mold wheel temperature is typically below the glass transition temperature (Tg) to ensure rapid cooling of the polymer as it melts. According to another embodiment of the invention, the thickness of the sheet is, for example, between about 100 μm and 500 μm or between 200 μm and 350 μm. The sheet is then biaxially stretched to form a polyester film. The biaxial stretching process is performed by preheating and holding the temperature above the glass transition temperature of the sheet material, and then simultaneously or sequentially in two perpendicular directions of the plane of the parallel sheet (machine direction (MD) and transverse direction (transverse direction, TD)) extends at a specific rate. In an embodiment of the invention, a biaxial extension procedure can be performed using a dual axis extender. The extension temperature of the biaxial extension is between about 60 ° C and 100 ° C or between 80 ° C and 90 ° C, and the elongation rate is between about 100 mm/min and 800 mm/min or between 300 mm/min and 500 mm/min. The stretching ratio is between about 1x1 and 9x9 or between 3x3 and 5x5.

In one embodiment, the ratio of polyester film-producing oligomers is less than about 1.2 wt%, such as between about 0.6 wt% and 1.2 wt%. Acid value about equal to less than 33eq / 10 ⁶ g, for example between about 5eq / 10 ⁶ g to 33eq / 10 ⁶ g, or between about 10eq / 10 ⁶ g to 25eq / 10 ⁶ g. The glass transition temperature (Tg) is between about 77 ° C and 100 ° C, for example between about 77 ° C and 90 ° C.

In still another embodiment, the hydrolysis resistance of the polyester film can be up to about 40 hours or even up to about 69 hours.

The above and other objects, features, and advantages of the present invention will become more apparent and understood, Ester product.

Preparation and properties of modified polyester ester granules

Example 1

Terephthalic acid monomer, ethylene glycol monomer and 1.0 mol% (based on the total number of moles of terephthalic acid monomer and ethylene glycol monomer), branched chain monomer 1 (glycerol, glycerol, Structure is , sold by Sigma-Aldrich , mixed, and polymerized at 280 ° C for 90 minutes to obtain modified polyethylene terephthalate (PET), which was then cooled to cold water for dicing. A modified polyester ester granule is obtained. Next, the intrinsic viscosity (IV), the glass transition temperature (Tg), the melting point (Tm), the acid value, and the ratio of the oligomer produced were measured, and the results are shown in Table 1. The measurement of the inherent viscosity (IV), the glass transition temperature (Tg), the melting point (Tm), the acid value, and the ratio of the production of the oligomer (oligomer) is as follows: inherent viscosity (IV): The sample was dissolved in phenol/trichloroethylene (TCE) (placed in a 30 ° C thermostat) and agitated by a stirring motor (115V.50/60CY, 1.2A, 1550RPM) to provide slight agitation. The viscometer is measured.

Glass transition temperature (Tg): 5-10 mg of sample was taken and heated to 800 ° C (temperature up rate of 20 ° C / min), and measured under a nitrogen using a thermogravimetry analyzer (TGA).

Melting point (Tm): 5-10 mg of the sample was measured under a nitrogen gas using a Differential Scanning Calorimeter (DSC).

Acid value: 1.0 g of the sample was taken and heated to 85 ° C by adding 80 ml of cresol (o-cresol), dissolved, and cooled to room temperature, and then 4 ml of water was added. After that, the sample was measured by acid-base titration with 0.1N potassium hydroxide (KOH) in ethanol (Ethanol) solution. Product (using the Metrohm 702 SM potentiometric titrator).

Ratio of oligomer produced: Thermal extraction: The oligomer in the polyester material was extracted using a soxhlet extractor. The oligomer content data was obtained by the weighing method.

Example 2~3

Examples 2 to 3 were carried out in the same manner as in Example 1 except that the addition amount of the branched monomer 1 was changed to 1.5 mol% and 3.0 mol%, respectively. Next, the intrinsic viscosity (IV), the glass transition temperature (Tg), the melting point (Tm), the acid value, and the proportion of the oligomer produced were measured for the modified polyester ester particles. The results are shown in Table 1. Shown.

Comparative example 1~3

In the same manner as in Example 1, only the addition amount of the branched monomer 1 was changed to 0 mol%, 0.5 mol%, and 5.0 mol%, respectively. Next, the intrinsic viscosity (IV), the glass transition temperature (Tg), the melting point (Tm), the acid value, and the proportion of the oligomer produced were measured for the modified polyester ester particles. The results are shown in Table 1. Shown.

Example 4

Terephthalic acid monomer, ethylene glycol monomer and 1.0 mol% (based on the total molar number of terephthalic acid monomer and ethylene glycol monomer), branched monomer 2 (symmetric trimellitic acid) , trimesic acid, structure is , sold by Sigma-Aldrich ), polymerization was carried out at 280 ° C for 90 minutes to form modified polyethylene terephthalate (PET), and the molten polyester was extruded to cold water for cooling. Pelletizing to obtain modified polyester ester granules. Next, the intrinsic viscosity (IV), the glass transition temperature (Tg), the melting point (Tm), the acid value, and the ratio of the oligomer produced were measured, and the results are shown in Table 2.

Example 5~6

Examples 5 to 6 were carried out in the same manner as in Example 4, except that the addition amount of the branched monomer 2 was changed to 1.5 mol% and 3.0 mol%, respectively. Next, the intrinsic viscosity (IV), the glass transition temperature (Tg), the melting point (Tm), the acid value, and the proportion of the oligomer produced by the hydrolysis of the modified polyester ester particles obtained are measured. 2 is shown.

Example 7

Terephthalic acid monomer, ethylene glycol monomer and 1.0 mol% (based on the total molar number of terephthalic acid monomer and ethylene glycol monomer), the branched monomer 3 (1, 2, Trimethyl trimellitate 4-methyltricarboxylate, structure , sold by Sigma-Aldrich , mixed, polymerization was carried out at 280 ° C for 90 minutes to obtain modified polyethylene terephthalate (PET), and the molten polyester was extruded to cool water and cooled. The pelletizing is carried out to obtain modified polyester ester pellets. Next, the intrinsic viscosity (IV), the glass transition temperature (Tg), the melting point (Tm), the acid value, and the ratio of the oligomer produced were measured, and the results are shown in Table 3.

Examples 8-9

In the same manner as in Example 7, only the addition amount of the branched monomer 3 was changed to 1.5 mol% and 3 mol%, respectively. Next, the intrinsic viscosity (IV), the glass transition temperature (Tg), the melting point (Tm), the acid value, and the proportion of the oligomer produced by the hydrolysis of the modified polyester ester particles obtained are measured. 3 is shown.

As shown in Tables 1-3, as the amount of the branched monomer increases, the acid value of the polyester ester granule decreases, and the acid value of the modified polyester ester granule can be reduced to about 33 eq/10 ⁶ g. The proportion of oligomers produced can be reduced to about 1.2% or less. From the results of the above comparative examples and examples, it can be seen that the addition of an appropriate branched monomer can increase the glass transition temperature (Tg), and can also greatly reduce the ratio of acid value to hydrolysis to produce oligomer.

Modified polyester ester particle hydrolysis resistance test

The modified polyester ester granules of Examples 1 to 3 and Comparative Examples 1 to 3 were subjected to hydrolysis resistance test under high temperature boiling (100 ° C) for 40 hours, and the change of inherent viscosity (IV) with time was observed. The result is shown in Figure 1. Further, the modified polyester ester granules of Examples 4 to 6 and Comparative Example 1 and Comparative Example 4 were subjected to hydrolysis resistance test under high temperature boiling (100 ° C) for 40 hours, and the inherent viscosity (IV) was observed with time. The change is changed and the result is shown in Figure 2. Further, the modified polyester ester granules of Examples 7 to 9 and Comparative Example 1 were subjected to a hydrolysis resistance test under high temperature boiling (100 ° C) for 40 hours, and the change of the inherent viscosity (IV) with time was observed. The result is shown in Figure 3. From the results of Figures 1 to 3 and Tables 1-3, it can be seen that the amount of the branched monomer is between 1 mol% and 3 mol%, which can simultaneously increase the glass transition temperature (Tg), and greatly reduce the acid value and hydrolysis. The effect of the ratio of the polymers.

Preparation and properties of polyester film

Example 10~12

The modified polyester ester granules of the above Examples 4 to 6 were dried under vacuum at 140 ° C for 8 hours, using a continuous extruder (model CF320401803 1/2 HP). It is made into a polyester film with a thickness of about 270μm, and then subjected to biaxial stretching processing, and the extension temperature is about 85~90°C and the elongation rate is about 300~500mm/min. Preheating is carried out for 5 minutes before stretching, and the polyester film is oriented to the longitudinal direction. The machine direction (MD) and the transverse direction (TD) direction are each extended by about 3 to 4 times, and then heat-set at about 200 to 230 ° C to obtain a prepared polyester film having an average film thickness of 30 ± 2 μm. The obtained film was measured for the ratio of acid value, Tg, and hydrolysis-producing oligomer, and the results were similar to those of Examples 4 to 6, and it was found that the film obtained from the ester particles was similar in properties to the ester particles. Further, the thermal expansion coefficient, the heat shrinkage ratio (150 ° C, 30 min) of the obtained polyester film, and the average film thickness were measured, and the results are shown in Table 4. The thermal expansion coefficient and the thermal shrinkage rate are measured as follows: Thermal expansion coefficient: The thermal mechanical analyzer (TMA) is used to detect the dimensional change of the sample heating.

Heat shrinkage rate (150 ° C, 30 min): The oven was first thermostated at 150 ° C for 1 hour, and then the 30*30 cm sample was placed in an oven. After 30 minutes, the sample was taken out and the dimensional change was measured.

Comparative Example 5~6

The modified polyester ester granules of Comparative Example 1 and Comparative Example 4 were dried at 140 ° C for 8 hours under vacuum, and a polyester film was formed by a continuous extruder (model: CF320401803 1/2 HP) to a thickness of about 270 μm. The biaxial stretching process is further carried out, and the extension temperature is about 85-90 ° C and the elongation rate is about 300-500 mm/min. The film is preheated for 5 minutes before stretching, and the polyester film is oriented in the machine direction (MD) and the transverse direction (transverse direction). The TD) direction is extended by about 3 to 4 times, and then heat-set at about 200 to 230 ° C to obtain a prepared polyester film having an average film thickness of 30 ± 2 μm. Further measuring the thermal expansion coefficient and heat recovery of the obtained polyester film The shrinkage ratio (150 ° C, 30 min), and the average film thickness are shown in Table 4.

It can be seen from the above examples that the addition of a proper proportion of the branched monomer can lower the heat shrinkage rate of the polyester film.

Polyester film thermomechanical analysis

The polyester films of Examples 10 to 12 and Comparative Examples 5 to 6 were subjected to thermal mechanical analyzer (TMA) (analysis conditions were a temperature scanning range of 30 to 220 ° C, and the temperature was raised at a heating rate of 10 ° C / min). The heat resistance of the film was tested, and the results are shown in Fig. 4 (the vertical axis is a shape variable). Comparative Example 4 began to show significant deformation at about 120 ° C, while Example 6 began to show significant deformation at about 180 ° C. As can be seen from Fig. 4, by adding an appropriate amount of a branched chain monomer, the heat resistance of the film can be improved.

Polyester film dimensional stability test

The polyester films of Comparative Examples 5 to 6 and Examples 11 to 12 were subjected to dimensional stability test, and scanned at 30 to 180 ° C for 3 趟, the heating rate was 10 ° C / min, and the cooling rate was 40 ° C / min. See Figure 5. As can be seen from Fig. 5, the addition of an appropriate amount of the branched chain monomer can improve the dimensional stability of the film.

Hydrolysis resistance test of polyester film

The polyester films of Examples 10 to 12 and Comparative Examples 5 to 6 were boiled under high temperature and high pressure (121 ° C, 100% RH) for 72 hours for hydrolysis resistance test. The hydrolysis resistance test method is to take out the film boiled under high temperature and high pressure at different times for tensile test (according to ASTM D882 standard test method), and the results are shown in Fig. 6. The film of Examples 10 to 12 has a hydrolysis resistance time of about 40 hours or more and even about 50 hours or more, wherein the film extension half cycle (hydrolysis time) of Example 2 can reach about 69 hours (the extension half cycle is 69 hours). That means, at 121 ° C, 100% RH environment for 69 hours, the film can still extend more than 50%). As can be seen from Fig. 5, the addition of a proper proportion of the branched monomer can increase the hydrolysis resistance time of the film.

In summary, since the polyester film of the present invention has a lower ratio of acid value to hydrolysis-producing oligomer, and good glass transition temperature and hydrolysis resistance, it is suitable for use in a high temperature or high humidity environment. Good weatherability.

While the invention has been described above in terms of several preferred embodiments, it is not intended to limit the scope of the present invention, and any one of ordinary skill in the art can make any changes without departing from the spirit and scope of the invention. And the scope of the present invention is defined by the scope of the appended claims.

Claims (18)

A polyester film which is a reaction product of a composition consisting essentially of terephthalic acid monomer; ethylene glycol monomer; and a single chain a body having a structure as shown in formula (I), formula (II), or formula (III), Wherein, X is independently a hydroxyl group, or -COOR, R is a C _1-6 alkyl group; the molar ratio of the terephthalic acid monomer and the ethylene glycol monomer is between 50:50 and 30:70. The addition ratio of the branch monomer is between 1.5 mol% and 3 mol%, based on the total number of moles of the terephthalic acid monomer and the ethylene glycol monomer. The polyester film according to claim 1, wherein the polyester film has an acid value of 33 eq/10 ⁶ g or less. The application of the polyester film of item 1 patentable scope, wherein the polyester film has an acid value ranging between 5eq / 10 ⁶ g to 33eq / 10 ⁶ g. The application of the polyester film of item 1 patentable scope, wherein the polyester film has an acid value ranging between 10eq / 10 ⁶ g to 25eq / 10 ⁶ g. The polyester film of claim 1, wherein the polyester film produces oligomers in a proportion of less than 1.2% by weight. The polyester film of claim 1, wherein the polyester film is thin The ratio of membrane-producing oligomers is between 0.6 wt% and 1.2 wt%. The polyester film of claim 1, wherein the polyester film has a glass transition temperature (Tg) of between 77 ° C and 100 ° C. The polyester film of claim 1, wherein the polyester film has a glass transition temperature (Tg) of between 77 ° C and 90 ° C. The polyester film of claim 1, wherein the polyester film polyester has a hydrolysis resistance time of at least 40 hours. The polyester film of claim 1, wherein the polyester film polyester has a hydrolysis resistance time of at least 69 hours. A method for preparing a polyester film, comprising reacting a chain monomer with a mixture, wherein the mixture is composed of a terephthalic acid monomer and an ethylene glycol monomer, wherein The branched monomer has a structure represented by formula (I), formula (II), or formula (III) Wherein, X is independently a hydroxyl group, or -COOR, R is a C _1-6 alkyl group; wherein the addition ratio of the branch monomer is between 1.5 mol% and 3 mol%, and the terephthalic acid is mono The total number of moles of the body and the ethylene glycol monomer is based on the reference. The preparation method according to claim 11, wherein the branch The chain monomer and the mixture are subjected to esterification polymerization, and the first modified polyester ester particles are obtained by dicing, and the first modified polyester ester particles are melted and extruded to form a thin plate, and the thin plate is biaxially stretched to form a polyester. film. The preparation method according to claim 12, wherein the temperature of the melt extrusion is between 200 ° C and 350 ° C. The preparation method of claim 12, wherein the polyester film produces oligomers in a proportion of less than 1.2% by weight. The preparation method according to claim 11, wherein the terephthalic acid monomer of the mixture and the ethylene glycol monomer are first subjected to an esterification reaction, and then the branched monomer is added to perform a upgrading reaction. The second modified polyester ester granule is obtained by dicing, and the second modified polyester granule is melted and extruded to form a thin plate, and the thin plate is biaxially stretched to form a polyester film. The preparation method of claim 15, wherein the terephthalic acid monomer and the ethylene glycol monomer have a molar ratio of between 1:1.2 and 1:1.4. The preparation method of claim 15, wherein the temperature of the melt extrusion is between 200 ° C and 350 ° C. The preparation method of claim 15, wherein the polyester film produces oligomers in a proportion of less than 1.2% by weight.