JPH0151566B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to polyester fibers, and more particularly to high modulus and low shrinkage polyester fibers and methods for producing the same. Polyester fibers, especially polyethylene terephthalate fibers, have high crystallinity, high melting point, and exhibit excellent properties in terms of heat resistance, chemical resistance, light resistance, strength-elasticity coefficient, etc., so they can be used not only for clothing, but also for example. Tire cords, conveyor belts, power transmission belts,
Widely used for rubber reinforcement materials such as hoses. In these fields, it is necessary to have high strength, and it is also extremely important to have high modulus and good dimensional stability. Polyethylene terephthalate fibers are used in many applications because they generally have a higher modulus than polyamide fibers such as nylon 6 and nylon 66. However, when compared with strong rayon fibers, fully aromatic polyamide fibers such as Keveler, carbon fibers, etc., its modulus is
It cannot be said that it is high, and on the contrary, its low modulus in high-temperature atmospheres is pointed out as a drawback. That is, in polyethylene terephthalate fibers, there is a contradictory relationship between modulus and dimensional stability, and when the dimensional stability is improved by decreasing the dry heat shrinkage rate, the modulus is disadvantageously reduced significantly. Such drawbacks are particularly noticeable in the field of reinforcing materials for rubber products. In line with the current demands for high quality and high performance rubber products, there is a desire for the emergence of polyethylene terephthalate fibers that have both low shrinkage and high modulus physical properties. It has been known for a long time that the mechanical properties of these fibers are greatly influenced by the microstructure, that is, the state of fiber orientation, the state of crystalline parts, and especially the state of amorphous parts. Many proposals have been made. Typical examples include a method of adding an inorganic substance such as talc, a low molecular compound such as a metal salt of an organic acid, or a method of adding a rigid polymer such as polycarbonate, polyethylene naphthalate, or phenolic resin. However, all of these methods have poor dispersion in polyethylene terephthalate.
Furthermore, depending on the type of rigid polymer, a random copolymerization reaction with polyethylene terephthalate occurs in the bag, causing a large increase in bag pressure, which causes a major problem in threadability. Furthermore, troubles tend to occur during the drawing heat treatment process, and the performance of the resulting fibers is also not fully satisfactory. On the other hand, an attempt to add polyethylene diphenyl-4,4'-dicarboxylate was made in
As seen in Japanese Patent No. 82019, in this case, it is difficult to achieve uniform dispersion in polyethylene terephthalate, and it is difficult to achieve a stable effect. In addition, if the amount added is increased, back pressure increases during spinning, and furthermore, yarn breakage and fluffing during drawing heat treatment are likely to occur, which is difficult to implement from the viewpoint of operability. As a result of intensive studies on modification by the above method, the present inventors block copolymerized polyethylene diphenyl-4,4'-dicarboxylate, a rigid polymer, with polyethylene terephthalate, and converted this block copolymer polyester into polyethylene. It has been discovered that when dispersed in terephthalate and spun and drawn, the resulting polyester fiber exhibits high modulus and low shrinkage due to the effect of the rigid polymer, and has good spinnability and drawability, and has developed the present invention. I reached it. That is, the present invention provides a polyethylene terephthalate/polyethylene diphenyl-4,4'-dicarboxylate block copolymerized with a polyester having ethylene terephthalate as a main constituent unit and polyethylene diphenyl-4,4'-dicarboxylate. A polyester fiber obtained by melt-spinning a mixture with a polymer and then heat-drawing it under conditions that simultaneously satisfy the following (i) to (ii), which are: (i) Stretching conditions: Stretching ratio: 3.0 times or more; Stretching temperature: Above the glass transition point (ii) Heat treatment conditions: Limited shrinkage of 10% or less or 15%
Under the following tension, the heat treatment temperature is 150 to 250°C. The present invention relates to a polyethylene fiber characterized in that the content of ethylene diphenyl-4,4'-dicarboxylate units is 0.3 to 15% by weight. In the present invention, the polyester forming the base of the fiber is mainly polyethylene terephthalate, but it may also be a copolyester containing a small amount (15 mol % or less) of a third component. Generally, polyethylene terephthalate is synthesized by reacting terephthalic acid or its ester-forming derivative and ethylene glycol or its ester-forming derivative in the presence of a catalyst under appropriate reaction conditions. Before the polymerization of this polyethylene terephthalate is completed, one or more suitable third components may be added to form a copolymerized polyester. Suitable third components include compounds having two ester-forming functional groups, aliphatic dicarboxylic acids such as oxalic acid, succinic acid, adipic acid, azelaic acid, sebacic acid, and alicyclic dicarboxylic acids such as cyclobutane dicarboxylic acid. acids, hexahydroterephthalic acid, decalindicarboxylic acid, etc.
Aromatic dicarboxylic acids, such as 5-sodium isofuselic acid, sulfoisophthalic acid, chlorterephthalic acid, bromoterephthalic acid, dichloroterephthalic acid, dibromoterephthalic acid, bromoisophthalic acid, naphthalene dicarboxylic acid, chlornaphthalene dicarboxylic acid, bromonaphthalene dicarboxylic acid acid,
Diphenyl ether dicarboxylic acid, diphenyl sulfone dicarboxylic acid, diphenoxyethane dicarboxylic acid, etc., oxycarboxylic acids such as glycolic acid, P-oxybenzoic acid, P-oxyethoxybenzoic acid, 4'-hydroxydiphenyl-4' -Hydroxy compounds such as carboxylic acids, such as propylene glycol, trimethylene glycol, diethylene glycol, tetramethylene glycol, pentamethylene glycol, hexamethylene glycol, occumethylene glycol, decamethylene glycol, cyclohexanedimethanol, bisphenol A, 1,4- Bis(β-hydroxyethoxy)benzene, 2,2′-bis(P-β-hydroxyethoxyphenyl)propane, bis(P-
β-hydroxyphenyl) sulfone, 2,2-bis(4-β-hydroxyethoxy-3,5-dichlorophenyl)propane, 2,2-bis(4-β
-Hydroxyethoxy-3,5-dibromphenyl)propane, bis(4-β-hydroxyethoxy-3,5-dichlorophenyl)sulfone, bis(4-β-hydroxyethoxy-3,5-dibromphenyl)sulfone, bis(4- β-hydroxyethoxy-3,5-dibromphenyl) sulfone, etc., or ester-forming derivatives thereof, 1
Examples include compounds having an ester-forming functional group, such as benzoic acid, naphthoic acid, and methoxypolyalkylene glycol. Compounds having three or more ester-forming functional groups, such as glycerin, trimethylolpropane, pentaerythritol, trimellitic acid, trimesic acid, and pyromellitic acid, may also be used within the range where the polymer is substantially linear. can do. The above polyester also contains matting agents such as titanium dioxide, stabilizers such as phosphoric acid, phosphorous acid, phosphonic acid and their esters, hydroxybenzene triazole derivatives, hydroxybenzophenone derivatives, cyanoacrylate derivatives, etc. It may also contain an ultraviolet absorber or the like. The intrinsic viscosity [η] of the polyester is preferably 0.50 to 1.20, particularly preferably 0.65 to 1.00. If [η] is less than 0.50, the resulting yarn may have high modulus and low shrinkage, but the strength will be insufficient, that is, the strength will not exceed 6 g/d, which is not preferred. On the other hand, if [η] exceeds 1.20, the melt viscosity will be too high, making it difficult to measure smoothly with the gear pump, resulting in poor discharge and poor spinnability.Also, in terms of strength, the [η] value will
Even if it exceeds 1.20, it will reach a plateau, so there is no benefit. In addition, the intrinsic viscosity [η] referred to in the present invention
is defined as follows. [η] = lim C→O1/C(ηr−1) In the formula, ηr is the viscosity of a diluted solution in a solvent divided by the viscosity of the solvent itself measured at the same temperature and in the same unit, and is called the relative viscosity. It is called. C is the concentration (g) of polymer per 100 c.c. of solution. The intrinsic viscosity [η] in the present invention is purity 98
35% or more orthochlorophenol as a solvent
Calculated from values measured at °C. Also, the strength is 20
When a load equivalent to 1/30 of the denier is applied to a sample with a sample length of 200 mm using a constant speed extension type tensile tester under standard conditions of ℃ and 65% PH, and the sample is pulled at a tensile speed of 200 mm/min. The load-elongation curve is recorded and the breaking strength of the sample at this time is divided by the denier of the sample. In the present invention, the block copolymer mixed with the polyester is a polyester consisting of polyethylene terephthalate and polyethylene diphenyl-4,4'-dicarboxylate (hereinafter abbreviated as diphenyl polyester). This diphenyl polyester is made by combining ethylene glycol or its ester-forming derivative with diphenyl-4,4'-
It is synthesized by reacting a dicarboxylic acid or its ester-forming derivative under appropriate conditions in the presence of a catalyst. The degree of polymerization of the diphenyl polyester is not particularly limited, but it is preferably one having a reduced specific viscosity (ηsp/c) of 0.05 or more at 30°C in orthophenol. When the reduced specific viscosity is less than 0.05,
In reality, it is difficult to call it a polymer, and it is difficult to exhibit the effect of a rigid polymer.Also, even if it is reacted with polyethylene terephthalate at high temperature to form a block copolymer, it forms a copolymer in a nearly random state, and such a copolymerized polyester Even if it is added to the base polyester and then spun and stretched, it is difficult to achieve the object of the present invention. This is thought to be because the amorphous portion that governs the mechanical properties of the fiber cannot be modified if the copolymer added is randomly polymerized. Any amount is acceptable depending on the high degree of polymerization.When the degree of polymerization is high enough, general solvents for measuring the degree of polymerization, such as orthochlorophenol, phenol/dichlorobenzene, phenol/trichlorophenol, phenol/tetrachloroethane, etc. Although it becomes insoluble and the solution viscosity cannot be measured and the degree of polymerization cannot be measured, it can be used in the present invention without any problems. In the present invention, the above-mentioned diphenyl polyester is reacted with polyethylene terephthalate in advance to form a block copolymer, which is then blended into the polyester serving as the base material. The amount of diphenyl polyester in the block copolymer should be between 2 and 40% by weight. If the amount of the block copolymer is less than 2% by weight, the effect of the rigid polymer cannot be obtained and the object of the present invention cannot be achieved. Moreover, if the amount is more than 40% by weight, the resulting copolymer tends to become a random copolymer, and such a copolymer also cannot obtain the effects of a rigid polymer. To synthesize a block copolymer, a predetermined proportion of polyethylene terephthalate and diphenyl polyester are mixed at a temperature higher than the melting point of diphenyl polyester.
This is preferably carried out by melt-mixing at a temperature of about 340 to 360°C. During this synthesis, there is no problem even if unreacted diphenyl polyester remains. In particular, if the remaining particles are made into fine particles of 1 μm or less, more favorable results tend to be obtained. When this residual material is large, problems tend to occur in the operability at the silk spinning stage. For example, troubles such as a sudden increase in spinning back pressure, deterioration in spinnability, yarn breakage during drawing heat treatment, and fluffing are likely to occur. Therefore, if residual giant particles are present, it is desirable to remove them using a wire mesh or the like. Note that a small amount (approximately 10 mol% or less) of tertiary polyester and/or polyethylene terephthalate used in the production of the block copolymer may contain
The components may also be copolymerized. As suitable third components, the compounds of - exemplified in the case of the polyester can be similarly exemplified. The amount of block copolymer added to the base polyester is such that the total amount of ethylene diphenyl-4,4'-dicarboxylate units in the product fiber is 0.3.
The amount should be ~15% by weight. 0.3% by weight
If it is less than 20%, the content of diphenyl polyester, which is a rigid component, is too small to produce any effect. On the other hand, if it exceeds 15% by weight, a large amount of block copolymer is added, which deteriorates spinnability and drawability, and also tends to cause a re-esterification reaction with the base polyester. The properties of the resulting fibers are not fully satisfactory. In particular, it is preferable that the amount of the block copolymer added be in the range of 0.5 to 40% by weight, while satisfying the above conditions. If the amount added is outside this range, it will be difficult to mix uniformly into the base polyester, and especially if it exceeds 40% by weight, the dispersion state of the block copolymer in the base polyester will be poor, resulting in back-up during spinning. Trouble, etc. in the pressure increase and drawing heat treatment process are likely to occur, and the performance of the obtained fibers also tends to be unsatisfactory. Any method can be used for adding the block copolymer to the polyester base and the subsequent melt spinning. For example, the purpose of adding the block copolymer can be easily achieved by adding and mixing it in a predetermined ratio in a hopper before spinning. Next, the mixed chips are melted at a temperature higher than the melting point of the base polyester and the spun yarn is wound once or without winding at a temperature higher than its glass transition point in one or two or more stages. Stretched more than twice as long and under tension of less than 15% of the constant length or 10
150~250℃, preferably under limited shrinkage of less than %
A method of heat treatment at 160-235°C is adopted. Heat treatment is usually carried out at -10% (shrinkage) to +15% (tension), but increasing the shrinkage lowers the Young's modulus, and increasing the tension tends to result in poorer dimensional stability; A range of +10% is preferred. The present invention will be specifically explained below with reference to Examples. In addition, the Young's modulus and the dry heat treatment rate at 180° C. in the examples were calculated by the following method. Young's modulus is measured using a constant speed extension type tensile tester under standard conditions of 20°C and 65% RH, with a sample length of 250 mm.
Apply a load equivalent to 1/30 of the denier to the sample,
The load-elongation curve was recorded when the sample was stretched at a tensile speed of 50 mm/min, and the strength when the sample was stretched by 1% was read and determined from the following formula. Young's modulus (Kg/cm ² )=F/D×900×δ Here, F is the strength value when the sample is stretched by 1%, D is the denier of the sample, and δ is the strength value of the sample when it is stretched by 1%. It is the specific gravity value. The dry heat shrinkage rate at 180℃ is measured by applying a load equivalent to 1/30 of the sample and measuring a sample of length l ₁ under no load.
Treat at 180℃ for 30 minutes, then leave at room temperature for 2 hours.
Length measured by applying the load mentioned above after leaving it for a while
From l ₁ , it was calculated using the following formula. Dry heat shrinkage rate (%) = l ₁ - l ₂ / l ₁ × 100 Preparation of block copolymer polyester 110 parts of dimethyl diphenyl 4,4'-carboxylate,
240 parts of ethylene glycol and 0.068 parts of calcium acetate hydrate were placed in a reactor equipped with a stirrer, and after completely melting the contents, transesterification was carried out at 230°C for 90 minutes under a nitrogen atmosphere. Next, 0.068 part of trimethyl phosphate was added to deactivate calcium acetate, and then 0.044 part of antimony trioxide was added and reacted for 60 minutes at 250°C under a nitrogen atmosphere. Then, the temperature was raised to 280°C and 100 Allowed to react for minutes. The contents became a slurry, and the pressure was reduced using a vacuum pump to completely solidify the contents. The solidified polymer was taken out, crushed into about 10 meshes, and put into the reactor again at 300℃ and under a reduced pressure of 0.1 to 0.2 mmHg.
Solid state polymerization for 18 hours. The obtained diphenyl polyester was insoluble in orthochlorophere, which was a solvent for measuring the degree of polymerization. The diphenyl polyester obtained in the above process was melt-blended with polyethylene terephthalate having an intrinsic viscosity of 1.10 at a high temperature of 350°C, and then extruded through a wire gauze to form chips. In addition, during melt blending, the content of diphenyl polyester was set to two types, 10% by weight and 50% by weight, and two wire meshes of 100 mesh and 400 mesh were used to change the viscosity of the unreacted diphenyl polyester. used. The sizes of the remaining particles in the obtained chips are as shown in the table.

[Table] Example 1 Chip A (diphenyl polyester used 10% by weight, size of residual particles in the chip less than μ) was mixed with polyethylene terephthalate with an intrinsic viscosity of 0.75.
Blend under the conditions shown below, temperature 300℃, speed
The fibers were spun at 1000 m/min and then drawn under the drawing conditions shown in the table to obtain a single fiber with a denier of 5 de.

[Table] The spinning and drawing conditions of the fibers obtained in this manner and the basic physical properties of the fibers are as shown in the table.

【table】

[Table] As shown above, when the size of the residual particles in the block copolymer is 1μ or less, spinnability and drawability are extremely good if the amount of block copolymer added is 40% by weight or less. . In addition, regarding the basic performance of the obtained fiber, when the content of ethylene diphenyl-4,4'-dicarboxylate is 0.3% by weight or more, the effect of rigid polymer chains can be seen, and it exhibits high modulus and low shrinkage performance. . On the other hand, the amount of block copolymer added was 40
If it exceeds % by weight, even if the remaining particles in the block copolymer are 1μ or less, the amount added is too large.
The increase in back pressure was somewhat high, and the occurrence of yarn breakage and wrap during spinning and drawing was also somewhat high. Also,
The performance of high modulus and low shrinkage did not necessarily improve significantly, and the strength decreased significantly. Comparative Example 1 In Example 1 No. 5, instead of the block copolymer, terephthalic acid/diphenyl-4,4'-dicarboxylic acid/ethylene having 10% by weight of ethylene diphenyl-4,4'-dicarboxylate units was used. Using a random copolymer consisting of glycol (No.
a), or the same except that instead of the block copolymer, fine particles of polyethylene diphenyl-4,4'-dicarboxylate (particle size 0.1 μ) are used and the amount added is 1% by weight (No. b) Single yarn denier 5de
fibers were obtained. The spinning and drawing conditions and basic physical properties of the fiber thus obtained are shown in the table below. Note that the results of Example 1 No. 5 are also listed.

[Table] As described above, when a random copolymer was used (sample No. a), no effect of rigid and straight molecular chains was observed, and high elastic modulus performance could not be obtained. On the other hand, when fine particles of polyethylene diphenyl-4,4'-dicarboxylate were used (sample No. b), although improvements in physical properties such as low shrinkage and high elastic modulus were observed, the degree of improvement was small, and the spinning The fiber properties and drawability were poor, and the occurrence of yarn breakage and lapping during spinning and drawing was high. Example 2 Chip B (amount of diphenyl polyester used: 50% by weight, size of residual particles in the chip: 1μ or less),
The mixture was blended with polyethylene terephthalate having an intrinsic viscosity of 0.75 at weight ratios of 1/99, 2/98, and 5/95, and spun and drawn in the same manner as in Example 1. The spinning and drawing conditions of the fiber thus obtained and the basic physical properties of the fiber are shown in the table.

[Table] If the amount of diphenyl polyester used in the block copolymer exceeds 40% by weight, a re-copolymerization reaction will occur with the base polyethylene terephthalate during melt spinning, even if the amount added is small. , the back pressure increases, and yarn breakage and lapping are more likely to occur during spinning and drawing. In addition, since it was a random copolymerized polyester, the basic physical properties were greatly reduced, and no effect of introducing rigid polymer chains was observed. Example 3 Chip C (amount of diphenyl polyester used: 10% by weight, size of residual particles in the chip: 2 to 3μ),
The mixture was blended with polyethylene terephthalate having an intrinsic viscosity of 0.75 at weight ratios of 5/95, 10/90, and 20/80, and spun and drawn in the same manner as in Example 1. The spinning and drawing conditions of the fiber thus obtained and the basic physical properties of the fiber are shown in the table.

[Table] As shown above, when the remaining particles in the block copolymer become large, the dispersion state in polyethylene terephthalate becomes extremely poor, the pack pressure increases greatly, and yarn breakage and wrap occur during spinning and drawing. will increase. In addition, because the dispersion is poor, the stretchability is reduced, so no effect of introducing rigid molecules was observed in terms of strength, especially modulus. Example 4 Chip A (amount of diphenyl polyester used: 10% by weight, size of residual particles in the chip: 1μ or less),
Blended with polyethylene terephthalate with an intrinsic viscosity of 0.75 at a weight ratio of 20/80, at a temperature of 300℃,
The fibers were spun at a speed of 1000 m/min and then stretched under the stretching conditions shown in the table.

【table】

[Table] The drawing state of the obtained fibers and the basic physical properties of the fibers are shown in the table.

[Table] When the stretching ratio was less than 3.0, only a product with low strength was obtained. Stretching heat treatment temperature is 150℃
If the temperature is below 250°C or above 250°C, lapping tends to occur, and the effect of introducing rigid molecules cannot be fully exhibited in terms of fiber performance. In addition, 15% during stretching heat treatment
Even if a tension of more than 10% or a contraction of 10% or more was applied, favorable results were not obtained.

Claims (1)

[Claims] 1. A polyester containing ethylene terephthalate as a main constituent unit and polyethylene diphenyl.
A mixture of polyethylene terephthalate and polyethylene diphenyl-4,4'-dicarboxylate block copolymer copolymerized with 4,4'-dicarboxylate is melt-spun, and then the following (i) to (ii) are carried out. A polyester fiber obtained by drawing heat treatment under conditions that satisfy the following conditions: (i) Drawing conditions: Stretching ratio: 3.0 times or more, drawing temperature: Glass transition temperature or more (ii) Heat treatment conditions: Under limited shrinkage of 10% or less or 15%
Under the following tension, the heat treatment temperature is 150 to 250°C. A polyester fiber characterized in that the content of ethylene diphenyl-4,4'-dicarboxylate units is 0.3 to 15% by weight. 2. The polyester fiber according to claim 1, wherein the amount of the polyethylene terephthalate/polyethylene diphenyl-4,4'-dicarboxylate block copolymer mixed is 0.5 to 40% by weight. 3 Polyethylene terephthalate/polyethylene diphenyl - unreacted polyethylene diphenyl of 4,4'-dicarboxylate block copolymer -
The polyester fiber according to claim 1 or 2, wherein the 4,4'-dicarboxylate is present in the form of fine particles of 1 μm or less. 4 When producing polyester fiber by melt spinning polyester whose main constituent unit is ethylene terephthalate, polyethylene diphenyl-
Polyethylene terephthalate made by block copolymerizing 2 to 40% by weight of 4,4'-dicarboxylate.
By adding polyethylene diphenyl-4,4'-dicarboxylate block copolymer, 0.3 ethylene diphenyl-4,4'-dicarboxylate units are added.
~1.5% by weight, the spun yarn after melt spinning is stretched to 3 times or more at a temperature above its glass transition point, and then 150 to 250°C under tension of 15% or less or limited shrinkage of 10% or less A method for producing polyester fiber characterized by heat treatment. 5. The method for producing polyester fibers according to claim 4, wherein the amount of the polyethylene terephthalate/polyethylene diphenyl-4,4'-dicarboxylate block copolymer added is 0.5 to 40% by weight. 6. A patent claim in which the polyethylene terephthalate/polyethylene diphenyl-4,4'-dicarboxylate block copolymer contains unreacted polyethylene diphenyl-4,4'-dicarboxylate as fine particles of 1μ or less A method for producing polyester fiber according to item 4 or 5.