JPS6349610B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel polyester film with excellent heat resistance, particularly to a novel biaxially oriented polyester film. Homopolyesters made of isophthalic acid and hydroquinone have been well known. Copolyesters obtained by copolymerizing this polyester with terephthalic acid, resorcinol, etc. are also known. These polyesters are known to provide heat-resistant films when press-molded. However, according to the study results of the present inventors, the polyester film obtained by the above method not only has a small Young's modulus, but also becomes white when kept at a high temperature of 200°C or higher, and its strength and elongation decrease significantly. It has become clear that this is not preferable as a transparent heat-resistant film. The present inventors have conducted further studies with the aim of obtaining a polyester film with excellent heat resistance from polyester that can be melt-molded, and have thus arrived at the present invention. That is, the present invention uses isophthalic acid residues (A) and hydroquinone residues (B) as main components, and the sum of isophthalic acid residues (A) and hydroquinone residues (B) constitutes all the component residues constituting the polyester. A film made of a melt-formable wholly aromatic polyester having a content of 85 to 95 mol% is stretched in both directions at a magnification of 1.5 times or more and an area magnification of 2.5 times or more, and at a temperature of 200°C or more. The Young's modulus and strength of the film in the mechanical axis direction and in the direction perpendicular to the mechanical axis at room temperature are 100 Kg/ ^mm2, respectively.
The above is a biaxially oriented polyester film having a weight of 7 kg/mm ² or more. In the present invention, a melt-moldable fully aromatic polyester containing isophthalic acid residues (A) and hydroquinone residues (B) as main components is one whose melting point is 400°C or less and whose isophthalic acid residues constitute the polyester. It is a wholly aromatic polyester in which the sum of (A) and hydroquinone residues (B) is 95 to 85 mol% of all component residues constituting the polyester. In the fully aromatic polyester of the present invention, the components that provide the isophthalic acid residue (A) and the hydroquinone residue (B) are, for example, terephthalic acid, naphthalene-
2,6-dicarboxylic acid, naphthalene-2,7-dicarboxylic acid, diphenyl-4,4'-dicarboxylic acid, diphenyl ether-4,4'-dicarboxylic acid, p-oxybenzoic acid, m-oxybenzoic acid,
Known aromatic dicarboxylic acids or known aromatic oxycarboxylic acids such as 6-oxy-2-naphthoic acid; resorcinol, 2,2-bis(4-oxyphenyl)propane, 2,2-bis(4-oxyphenyl)butane , 1,1-bis(4-oxyphenyl)cyclohexane, phenolphthalein,
4,4-dioxydiphenyl ether, 4,4'-
Known aromatic dioxy compounds such as dioxydiphenyl, 2,6-dioxynaphthalene, and 1,5-dioxynaphthalene can be mentioned. Among these, compounds such as resorcinol and 2,2-bis(4-oxyphenyl)propane are preferably used. The wholly aromatic polyester of the present invention is preferably produced by a combination of the conventionally known melt polymerization method and solid phase polymerization method, and in this case, by selecting the polymerization conditions described below, it is possible to obtain particularly excellent stretchability. It is preferable to use a polymer with Preferred specific examples of the polymerization method for producing the wholly aromatic polyester used in the present invention are as follows: 1) Aryl ester of isophthalic acid, optionally further aryl ester of other aromatic dicarboxylic acid or aromatic oxycarboxylic acid 2) isophthalic acid, optionally another aromatic dicarboxylic acid or aromatic oxycarboxylic acid, and hydroquinone, optionally. further heat-reacts another aromatic dioxy compound and diaryl carbonate to esterify the carboxylic acid with diaryl carbonate,
This method includes polymerization. Among the methods for producing the fully aromatic polyester, 1)
The method described above is particularly preferred since there is no possibility of introducing carbonate bonds into the polyester. A catalyst is preferably used in the above-mentioned polyester production method. This type of transesterification catalyst has conventionally been used as a catalyst, for example, among compounds containing metals such as calcium, magnesium, strontium, barium, lanthanum, cerium, titanium, manganese, cobalt, zinc, germanium, tin, antimony, and bismuth. Those known as are preferably used. More specific compounds include magnesium acetate, calcium benzoate, strontium acetate, lanthanum carbonate, cerium oxide, titanium, tetrabutoxide, manganese acetate, cobalt acetate, zinc acetate, germanium oxide, stannous acetate, and antimony trioxide. , bismuth trioxide, etc. The preferred amount of these catalysts to be used is 0.001 to 0.2 gram atoms, calculated as metal atoms contained in the catalyst, per 100 moles of the total acid components constituting the polyester. These catalysts are usually added to the reaction system from the beginning of the reaction. The wholly aromatic polyester used in the present invention is usually polymerized according to the polymerization method described above,
When performing melt polymerization, the polymerization temperature is 250 to 360℃,
Preferably, the temperature is 270 to 340°C. Melt polymerization is preferably carried out at a relatively low temperature (for example, 250 to 300°C) under normal pressure at the initial stage of polymerization. During this time, compounds produced by the reaction, such as phenol, are distilled out of the reaction system. When the reaction rate calculated from the distilled amount of by-products reaches 50% or more, the pressure of the reaction system is gradually reduced and the temperature is raised at the same time to 360℃ or less.
Preferably, the melt polymerization is further carried out and completed at a temperature of 340° C. or lower. The prepolymer thus obtained is usually a relatively low polymer with a reduced viscosity (ηsp/C) of 0.6 or less. If the melt polymerization method alone is used to obtain a high polymer and the reaction is carried out at high temperature for a long period of time, branching or crosslinking reactions occur as side reactions, so that it is difficult to obtain the polyester film that is the object of the present invention even if the film is stretched. The prepolymer obtained by the above melt polymerization is preferably subjected to solid phase polymerization to form a high polymer suitable for film formation. High-phase polymerization is carried out by forming the prepolymer obtained by melt polymerization into granules of a predetermined size, such as chips, pellets, powder, etc., and under conditions where the granules do not fuse together and form blocks. is preferable. As the solid phase polymerization progresses, the granules undergo
Since the fusion temperature increases, the solid state polymerization temperature can be gradually increased. It is preferable to stir the granules during this time. The solid phase polymerization temperature is selected from a temperature at which the polymerization reaction proceeds and does not block, and is usually about 230 to 320°C, preferably about 250 to 300°C. Further, the reaction atmosphere is preferably an atmosphere under an inert gas flow (for example, under a nitrogen gas flow) or under reduced pressure, and the latter is particularly preferred. The solid phase polymerization time depends on the degree of polymerization of the prepolymer, the desired degree of polymerization, the shape and size of the granules,
Determined by temperature, atmosphere, etc. Preferred polyesters for obtaining the polyester film of the present invention have a reduced viscosity of 0.6 or more, preferably 0.7 or more and 1.5 or less. This polyester can be made into the desired film by melting it at a temperature above its melting point, preferably below 400°C, melt-extruding it through a slit, then biaxially stretching, and further heat-setting. The slit used has a width of, for example, 0.1 mm to 5 mm. The unstretched film extruded from the slit is then biaxially stretched by conventionally known means. It is appropriate to select the stretching temperature between 180 and 250°C, and the stretching ratio is usually 1.5 in the machine axis direction and in the direction perpendicular to the machine axis.
The area magnification is 2.5 times or more. Preferably 1.5 times or more in both axial directions and 3.0 times or more in area magnification, more preferably 1.5 times or more in both axial directions and 4.0 in area magnification.
This is a magnification that is more than double. If the stretching ratio is too small, it is difficult to achieve the desired effect. After the polyester film of the present invention is biaxially oriented under the above conditions, it is heat-set for the purpose of further improving dimensional stability. This heat setting is performed at a temperature of 200℃ or higher and below the melting point of polyester.
It is desirable to carry out the process at a temperature 20°C or more lower, preferably from 250°C to about 20°C below the melting point of the polyester.
Perform in a temperature range down to low temperatures. The heat setting time is selected to be 2 seconds or more, preferably 10 seconds to 5 minutes. Through such operations, the Young's modulus and strength at room temperature in the machine axis direction and in the direction perpendicular to the machine axis direction are respectively 100 Kg/mm ² or more (preferably
150Kg/mm ² or more), 7Kg/mm ² or more (preferably 8
A heat-set biaxially oriented polyester film having a weight of at least 10 Kg/mm ² , particularly preferably at least 10 Kg/mm ² is obtained. Further, this biaxially oriented polyester film has a shrinkage rate at 250° C. of 10% or less, preferably 3% or less, particularly preferably 2% or less, and has excellent dimensional stability. Furthermore, since this polyester film has an elongation of 5% or more in both the film's mechanical axis direction and the direction perpendicular to the machine axis direction at room temperature, it also has sufficient flexibility required as a film. Furthermore, unlike films obtained by conventional pressing methods, the film has excellent transparency, so it can be used as a film for metal deposition, a film for flexible printed wiring boards, a film for electrical insulation, etc. In the present invention, the strength, elongation, and Young's modulus of the film are determined by subjecting a film with a width of 5 mm and a sample length of 20 mm to an Instron tensile tester at a tensile rate per minute.
This was determined as 100%. The reduced viscosity of polyester was determined by dissolving 120 mg of the polymer in 10 ml of a mixed solvent of phenol and tetrachloroethane (phenol:tetrachloroethane (weight ratio) = 4:6) and using an Ostwald viscometer at 35°C. Furthermore, the melt viscosity (μ) was determined by filling 1 g of the sample into a cylinder with a cross-sectional area of 1 cm ² equipped with a nozzle of 1 mm in diameter and 5 mm in length using a flow tester, and then under pressure at a temperature of 380 ° C. It was determined by the following formula after melt extrusion. μ=πPr ⁴ /8LQ [In the formula, P is pressure (dyne/cm ² ), r is nozzle radius (0.05cm), and L is nozzle length (0.5
cm), and Q is the polyester discharge speed (cc/
sec). Furthermore, the melting point of the polyester was determined by differential thermal analysis using a crystallized sample in a nitrogen stream at a humidification rate of 10° C./min. The present invention will be further explained below with reference to Examples. In addition, parts in the examples mean parts by weight. Example 1 190.80 parts of diphenyl isophthalate, 58.08 parts of hydroquinone, 14.52 parts of resorcinol, and 0.088 parts of stannous acetate were charged into a polymerization kettle, and the mixture was heated at 250 to 250 parts in a nitrogen stream.
The mixture was heated to 290° C. for 3 hours, and 68 parts of phenol (approximately 60% of the theoretical amount) produced as a result of the reaction was distilled off. Next, the pressure of the reaction system was gradually reduced and the reaction temperature was raised at the same time, and it took about 1 hour to reduce the pressure to 20 mm.
Hg, the reaction temperature was set to 340℃, and under these conditions an additional 30
Polymerization continued for minutes. The reduced viscosity of the obtained polymer was 0.60. At this point, the melt polymerization is stopped, and the polymer is ground into 12 to 20 meshes after cooling, and again
Solid phase polymerization was carried out at 250°C under a reduced pressure of 0.2 mmHg for 2 hours and then at 280°C under a reduced pressure of 0.2 mmHg for 6 hours. The melting point of the obtained highly polymerized polymer was 355°C,
The melt viscosity at 380℃ and shear rate of 100sec ^-1 is
It was 15,000 poise. This high polymerization degree polymer is melted at 380℃ and extruded through a T-die with a slit width of 1.5mm.
2.2 times, then perpendicular to the machine axis at a temperature of 220℃
The stretched film was stretched 2.3 times and then heat treated at a constant length of 280° C. for 30 seconds. Table 1 shows the performance of the obtained film. Examples 2 to 3 190.80 parts of diphenyl isophthalate, 55.44 parts of hydroquinone, 28.73 parts of bisphenol A, and 0.070 parts of antimony trioxide were charged into a polymerization pot, and heated in a nitrogen stream at a temperature of 250 to 285°C for 3 hours to complete the reaction. 73 parts of phenol (approximately 65% of the theoretical amount) to produce the result
was distilled out. Next, the pressure of the reaction system was gradually reduced and the reaction temperature was raised at the same time, and it took about 1 hour to reduce the pressure to 20 mm.
Hg and the reaction temperature was 330°C, and polymerization was continued under the same conditions for an additional 30 minutes, and then at 5 mmHg and 330°C for 15 minutes. The reduced viscosity of the obtained polymer was 0.47. After stopping the melt polymerization and cooling the polymer
Grind into 12-20 mesh and again under reduced pressure of 0.2mmHg
2 hours at 250℃, then 20 minutes at 270℃ under reduced pressure of 0.2mmHg.
Solid phase polymerization was carried out for hours. The melting point of the resulting highly polymerized polymer was 355℃, and the shear rate was 380℃.
The melt viscosity at 100 sec ^- ₁ was 10,000 poise. This high polymerization degree polymer was melted at 370℃ and extruded through a T-die with a slit width of 1.5mm.
Then, the biaxially stretched film was stretched 2.0 times in the direction perpendicular to the machine axis at the same temperature, and then the biaxially stretched film was stretched at a constant temperature of 270.
℃ (Example 2) or 290 ℃ (Example 3) for 30 seconds. Table 1 shows the performance of the obtained film. 【table】

Claims (1)

[Claims] 1 Isophthalic acid residue (A) and hydroquinone residue
(B) is the main component, and the sum of isophthalic acid residues (A) and hydroquinone residues (B) is 85 to 95 mol% of the total component residues constituting the polyester, which is melt-formable and wholly aromatic. A film made of polyester is stretched in two axial directions at a magnification of 1.5 times or more and an area magnification of 2.5 times or more, and heat-set at a temperature of 200°C or more, and the mechanical axis of the film and the mechanical axis. The Young's modulus and strength at room temperature in the direction perpendicular to the direction are respectively 100Kg/mm ² or more and 7Kg/
Biaxially oriented polyester film with a size of mm ² or more.