JPS6343426B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a biaxially stretched film that has excellent slip properties and abrasion resistance and has a small amount of elution. Today, biaxially stretched polyester films, especially polyethylene terephthalate, have excellent properties such as tensile strength, tear strength, modulus of elasticity, transparency, chemical resistance, and heat resistance, and are used for gold and silver thread, transfer marks, and plate making. It is widely used in many fields such as mold release, photography, packaging, electrical insulation materials, capacitor dielectrics, and magnetic recording media. However, such polyester films have different required properties depending on their use. For example, so-called translucent films used for gold and silver thread, transfer marks, plate making, mold release, etc., have poor workability when handling the film. Particularly desirable is one that is excellent and does not impair transparency. Furthermore, in the case of packaging films, especially food packaging films, it is essential that they be hygienically safe. Further, when polyester films are handled, white powdery substances are often produced due to abrasion between the films or between the films and the base material, which causes dropouts in films for magnetic tapes, for example. A characteristic commonly required for all uses of polyester films containing these is excellent workability when handling the film, and in order to improve this, it is necessary to reduce the slipperiness, that is, the coefficient of friction, of the polyester film. In some applications, good slipperiness is desired even at the cost of transparency. In order to improve this slipperiness, methods using antistatic agents or lubricants have been proposed, but it is difficult to put them into practical use because of deterioration in electrical properties, deterioration in work efficiency, and increase in cost. Various methods have been proposed to improve slipperiness, but the most commonly used method is to include an inert substance in the film, and these methods can be broadly divided into two types. . One method is called the precipitation method, which utilizes calcium salt fine particles of polyester oligomers that are formed and precipitated in polyester when a calcium compound is used as a transesterification catalyst. Both the method of adding an acid and the method of adding terephthalic acid and calcium acetate in the polycondensation stage to precipitate the calcium salt of the polyester oligomer precipitate fine particles in the reaction system. There is also a method in which fine particles are precipitated by a similar method using a lithium compound instead of a calcium compound. In these cases, there is also a method of obtaining precipitated particles under conditions in which one or more phosphorus compounds coexist. However, when trying to improve slipperiness using these precipitated particles, although they have the advantages of being easy to operate, producing polymers at low cost, and extending the filter life, the amount and diameter of the precipitated particles changes easily, making it difficult to control slipperiness. Another disadvantage is that the film has insufficient slipperiness in spite of its high turbidity, and when recycled, it no longer retains its original slipperiness. That is, in general, to produce polyester film, the raw material polyester is chipped, and the chips are extruded into a sheet at a temperature below the glass transition point and biaxially stretched. Due to uneven thickness and uneven stretching, some parts cannot be used as products and are used as recycled products. This process is industrially extremely important from the viewpoint of resource saving and reducing product costs. From this point of view, it is desirable to have a raw material whose properties as a film do not deteriorate even if it is recycled and used. Another method that is contrasted with the precipitation method is the addition method, in which calcium carbonate, kaolin,
Talc, silica, etc. are added as they are or after being made into fine particles during polyester synthesis or molding. The method of adding these inorganic compounds can adjust the particle size and amount of fine particles,
Since these fine particles are not easily destroyed by stretching, the reproducibility of the results is good, but unnecessary coarse particles are often mixed in. In order to remove these coarse particles, a classification operation and, if necessary, a crushing operation as a pretreatment are required, which makes the operation complicated. Moreover, even after such operations, the contamination of coarse particles cannot be avoided. Even if fine particles with very few coarse particles are obtained, it is generally extremely difficult to uniformly disperse an inorganic compound in polyester, which is an organic substance. The presence of foreign substances other than particles, coarse particles of inorganic compounds, or agglomerated particles due to poor dispersion will adversely affect the electrical properties of films for capacitors, and increase the generation of white powder and dropouts in films for magnetic tapes. This causes the film quality to deteriorate. Another disadvantage of adding inorganic compound particles is that the filter life is shortened, but as a result of detailed studies, the present inventors have found that the method of adding such inorganic compound particles When comparing a film obtained from a polyester produced by a polyester method and a film obtained from a polyester produced by a precipitation method, it was found that the latter is more suitable for packaging, especially for food packaging. In other words, packaging techniques using polyester film include vacuum packaging, gas-filled packaging, skin blister packaging, heat shrink packaging, and heating packaging, all of which are often used for packaging processed foods. In addition to workability, properties required for polyester films for use include physical strength, barrier properties, and stability against heat and chemicals, and one of the most important properties is hygiene. This hygiene means tasteless, odorless,
It refers to non-toxicity, etc., and the elution amount in water or a liquid mainly composed of water can be used as an indicator, and it is desirable that the elution amount is smaller. According to the findings revealed for the first time by the present inventors, the amount of elution from a polyester film containing an inorganic compound is greater than that obtained by a precipitation method. This is thought to be because some of the added inorganic compounds dissolve into the water. The present inventors took advantage of the long filter life and small elution amount, which are the advantages of precipitated particles, and combined them with the properties required for polyester films, such as abrasion resistance even when recycled and used. As a result of intensive studies in order to provide properties such as excellent slipperiness and transparency, we found that an insoluble material which is substantially covalently bonded to the precipitated particles having a specific particle size and amount and a specific particle size and amount of polyester; The present invention was completed by discovering that this can be achieved by combining it with an infusible crosslinked polymer. That is, the average particle size precipitated in the reaction system of the present invention
Average particle size substantially covalently bonded to polyester with 0.01-0.6% by weight of inert material particles of 0.5-5μ
The present invention relates to a polyester film containing 0.001 to 4% by weight of crosslinked polymer fine powder of 0.1 to 5μ. The present invention will be explained in more detail below. The polyester film in the present invention is a polymer mainly composed of polyethylene terephthalate,
For example, polyethylene terephthalate homopolymers, copolymers containing at least 80 mole % of ethylene terephthalate units, block polymers, etc. can be obtained by blending them as they are or with other polymers or various additives, and then melting and stretching the resulting polymers. . The polymer can be produced by polymerizing terephthalic acid or its ester-forming derivatives, such as dimethyl terephthalate and ethylene glycol, using a conventional method as main starting materials. In the present invention, the inert substance particles precipitated in the reaction system are those that are precipitated in the reaction system by, for example, polymerizing a system using an alkali metal or alkaline earth metal compound as a transesterification catalyst by a conventional method. Alternatively, precipitation may be carried out by adding terephthalic acid during transesterification or polycondensation reaction. In these cases, one or more phosphorus compounds such as phosphoric acid, trimethyl phosphate, triethyl phosphate, tributyl phosphate, acidic ethyl phosphate, phosphorous acid, trimethyl phosphite, triethyl phosphite, and tributyl phosphite are used. It's okay to let it exist. Furthermore, in the case of going through an esterification step, inert material particles can be precipitated by these methods.
For example, an alkali metal or alkaline earth metal compound is present before or after the completion of the esterification reaction,
The polymerization reaction is carried out in the presence or absence of a phosphorus compound. In any case, the fine precipitated compounds produced during the polyester production reaction in the present invention contain one or more elements such as calcium, lithium, antimony, and phosphorus. For example, when calcium acetate is used as a transesterification catalyst, a calcium compound estimated to have the following composition consisting of calcium terephthalate and a calcium salt of a polyester oligomer is precipitated during the polymerization reaction. Furthermore, when a phosphorus compound is used in combination with this system, it is thought that in addition to the above formula, a portion of a compound presumed to have the following structural formula is precipitated. When a lithium compound is used instead of a calcium compound, a compound estimated to have the following structure will precipitate during polycondensation. When a phosphorus compound is used in combination with this system, the following compounds are thought to precipitate in addition to the formula. Furthermore, when a calcium compound and a lithium compound are used together, it is thought that complex compounds represented by the above formula and the following formula will precipitate. Furthermore, if a phosphorus compound is used in combination with this system, it is presumed that in addition to the above formulas, complex compounds such as those represented by the following formula will be precipitated. In any case, in the present invention, these precipitated particles must be contained in the polyester film in an amount of 0.01 to 0.6% by weight, preferably 0.05 to 0.4% by weight. If the content of precipitated particles is less than 0.01% by weight, the slipperiness of the film will be insufficient, while if the content of precipitated particles exceeds 0.6% by weight, the slipperiness will no longer be improved, and on the contrary, the transparency of the film will decrease. Sexuality becomes worse. Further, the average particle size of the precipitated particles must be 0.5 to 5 μm. This is because if the average particle size is less than 0.5μ, the effect of developing slipperiness is insufficient;
If the particle size exceeds 5μ, the life of the filter during film formation will be shortened even though the particles are precipitated particles, and the film will become marbled. The average particle diameter of the precipitated particles is particularly preferably 1 to 4 microns. Since there are a wide variety of methods for producing precipitated particles that can be used in the present invention, it is not possible to discuss all of them in detail, but the following examples can be cited as specific examples. In other words, a lithium compound is used as a transesterification reaction catalyst for all acid components constituting polyester.
When 0.1 to 0.5 mol% is used to complete the polycondensation reaction, 0.05 to 0.3 precipitated particles with an average particle size of 0.5 to 2μ
% by weight, and in this case, if 0.5 to 1.5 times the mole of phosphoric acid is added to the lithium compound after the transesterification reaction is completed and the same operation is performed, precipitation with an average particle size of about 0.5 to 1μ can be obtained. A polyester containing 0.05-0.2% by weight of particles is obtained. In addition, when a trialkyl ester such as trimethyl phosphate, triethyl phosphate or tributyl phosphate is used in place of phosphoric acid, the amount of precipitated particles becomes 0.1 to 0.5% by weight. Calcium compounds as transesterification catalysts
When the polycondensation reaction is completed using 0.05 to 0.15 mol%, the precipitated particles with an average particle size of about 2 to 5 μ
A polyester containing 0.4% by weight can be obtained, and if terephthalic acid is added after the transesterification reaction in this operation, the average particle size of the precipitated particles can be reduced.
It will be about 0.5 to 2μ. Note that, as a matter of course, the particle size and amount of the precipitated particles also depend on the polymerization conditions, particularly the temperature and pressure, and the examples shown above are only some of the results. The polyester film of the present invention is characterized by the use of an insoluble and infusible crosslinked polymer fine powder that is substantially covalently bonded to the precipitated particles having a specific particle size and amount and a polyester having a specific particle size and amount. It is in. In other words, although the precipitated particles alone can improve slipperiness to some extent, they do not improve wear resistance.
Moreover, when recycled and used, the slipperiness deteriorates, and the abrasion resistance remains insufficient as a matter of course. The present inventors have found that to improve these drawbacks, it is possible to use additive particles in combination, but conventional methods of adding metal compounds, such as oxides or inorganic salts of groups 1 and 2 of the periodic table, have been found. It has been found that the method of adding particles selected from the following shows other disadvantages, namely, lack of transparency, shortened filter life, peeling of the particles themselves from the film, and increased elution amount. The first three of these drawbacks are due to the lack of affinity between the additive particles and the polyester. Since the crosslinked polymer fine powder itself is an organic substance, it is much more compatible with polyester than inorganic compounds. However, the dispersibility of fine polymer powders such as polytetrafluoroethylene, which do not have groups that react with polyester, is not always sufficient and coarse particles are often formed. Therefore, in order to sufficiently uniformly disperse the crosslinked polymer fine powder, it is necessary to react the particles with polyester or a polyester raw material and embed them in the polyester as particles having a strong bond with the polyester. Examples of groups that can react with such polyesters or polyester raw materials to form covalent bonds include ester groups, carboxyl groups, hydroxyl groups, epoxy groups, and amino groups. Another feature of the crosslinked polymer fine powder used in the present invention is that it has a crosslinked structure. That is, the fine polymer powder having the crosslinked structure is insoluble and infusible even at high temperatures during synthesis or molding of polyester, and therefore can be dispersed in polyester while maintaining its original shape at the time of addition. The crosslinked polymer fine powder used in the present invention will be explained in more detail below. The crosslinked polymer used to produce the crosslinked polymer fine powder of the present invention generally includes a monovinyl compound (A) having only one aliphatic unsaturated bond in the molecule, and a monovinyl compound (A) having two or more aliphatic bonds in the molecule as a crosslinking agent. A copolymer with a compound (B) having an unsaturated bond of the group B is used, but it is not limited to these, and any crosslinked polymer having a group that can react with polyester and form a covalent bond can be used. good. Examples of the compound (A) which is a component of the copolymer include acrylic acid, methacrylic acid, and methyl or glycidyl esters thereof, maleic anhydride and its alkyl derivatives, vinyl glycidyl ether, vinyl acetate, vinylbenzene derivatives, etc. I can do it. Further, examples of the compound (B) include divinylbenzene and divinylsulfone.
One or more types of each of compounds (A) and (B) are used, but these systems may also be copolymerized by adding ethylene or styrene. Further, a compound having a nitrogen atom may be copolymerized. Fine polymer powders containing nitrogen atoms tend to give polyester a coloration, particularly a yellowish tinge, but they can be used in applications where this is not a problem. Typical examples of these copolymers include copolymers of methyl methacrylate and divinylbenzene, or methyl acrylate and divinylbenzene. In addition, if these crosslinked polymers having alkyl ester groups are saponified or copolymerized using methacrylic acid in place of methacrylic esters and acrylic acid in place of acrylic esters, crosslinked polymers having carboxyl groups can be easily obtained. molecules can be obtained. Commercially available weakly acidic cation exchange resins have a crosslinked structure and carboxyl groups, and therefore can be suitably used as the crosslinked polymer used in the present invention. Further, a crosslinked polymer having an alkyl ester group may be used as an intermediate raw material. As a polymerization initiator for copolymerizing compound (A) and compound (B), well-known chemical radical initiators such as azoisobutyronitrile, benzoyl peroxide, t-butyl peroxide, and cumene hydroper can be used. Although it is convenient to use an oxide or the like or to irradiate ultraviolet rays, polymerization may also be initiated simply by heating. In any case, the particles used in the present invention must be a crosslinked polymer having a group capable of covalently bonding with the polyester, and it can be confirmed, for example, by the following method that the two have actually reacted. In other words, the rate of formation of a covalent bond between the polyester and the functional group of the crosslinked polymer varies depending on the type and concentration of the end group of the polyester, the type and concentration of the functional group of the crosslinked polymer, the type of reaction medium, and the reaction temperature. For example, bis(β-hydroxyethyl) terephthalate (hereinafter referred to as BHET), which is a monomer of polyethylene terephthalate, and a methacrylic acid-divinylbenzene copolymer (divinylbenzene content 10% by weight, hereinafter referred to as MA-DVB) with an average particle size of 2.5μ. When the decrease in carboxyl groups and increase in ester groups in the MA-DVB copolymer were measured using the method described below, the esterification rate was approximately 60% in 3 hours. %, it was almost 100% at 6 hours. Measuring method of esterification rate: Cross-linked polymer and polyester (or BHET)
Add 100 g of the reaction product to 900 g of a phenol/tetrachloroethane mixed solvent (1/1 weight ratio), heat and dissolve it, and then filter the residue using paper (Toyo Paper Co., Ltd. No. 5C) to dissolve 50 ml of phenol/tetrachloroethane. Wash with a tetrachloroethane mixed solvent and then with 50 ml of chloroform, and then dry the filtrate under reduced pressure at 90° C. for 5 hours. Next, approximately 0.1 g of the dried supernatant was accurately weighed, placed in a test tube, 10 ml of 0.2N sodium hydroxide was added, and the mixture was stirred at room temperature for 1 hour.
Take ml and back titrate with 0.1N hydrochloric acid. The carboxyl group concentration in the crosslinked polymer is calculated using the following formula. Carboxyl group concentration = 0.2×f ₁ ×10−0.1×f ₂ ×y×2/x [equivalent/Kg] where f ₁ : 0.2N sodium hydroxide factor f ₂ : 0.1N hydrochloric acid factor x : Weighed Weight of filtrate [g] y: Amount of hydrochloric acid required for back titration [ml] The esterification rate can be determined by the following formula using the measured carboxyl group concentration. Esterification rate = AB/A x 100 [%] where A: Carboxyl group concentration before reaction [equivalent/Kg] B: Carboxyl group concentration after reaction [equivalent/Kg] In this MA-DVB copolymer It can also be confirmed by the following method that the carboxyl group reacts with the polyester-forming component to form a covalent bond. In other words, the infrared absorption spectrum of the MA-DVB copolymer before reaction has a wavelength of 1700cm based on the carboxyl group.
Although absorption at ^-1 is clearly observed, absorption at 1730 to 1740 cm ^-1 due to ester groups is not observed at all. However, when we examined the infrared absorption spectrum after reacting the particles with BHET at 200℃ for 6 hours, we found that strong absorption was observed at 1730 to 1740 cm ^-1 .
Absorption of 1700 cm ^-1 could not be observed. This result is in agreement with the result obtained from the measurement of the esterification rate. As described above, the insoluble and infusible crosslinked polymer used in the present invention must be able to substantially form covalent bonds with the hydroxyl groups and carboxyl groups in the polyester, but the concentration of the functional group is 1 kg of the crosslinked polymer. 1 to 15 equivalents, particularly 3 to 15 equivalents, are preferred. In addition, the degree of crosslinking of the crosslinked polymer is 8 to 50%, especially 9
~45% is preferred. The degree of crosslinking is a numerical value defined by the following formula, but if this value is less than 8%, it becomes difficult to grind, and even if it exceeds 50%, there is no difference in the ease of grinding, and the density of the functional group decreases, so the bonding strength with polyester becomes poor. Degree of crosslinking = weight of divinyl compound / total weight of monomer x 100
(%) The average particle size of the crosslinked polymer fine powder used in combination with precipitated particles in the present invention must be 0.1 to 5 μm. If the average particle size is less than 0.1μ, the wear resistance will not be improved and there will be little effect on imparting slipperiness. On the other hand, if the average particle size exceeds 5 μm, no matter how good the dispersibility in the polymer is, the filter life during film formation will be shortened and the frequency of filter replacement will increase, resulting in a decrease in productivity. To obtain the particles used in the present invention with an average particle size of 0.1 to 5μ, there is a method of directly obtaining the monomers by suspension polymerization or emulsion polymerization, but the stirring during the reaction, concentration,
The particle size obtained tends to change due to slight variations in temperature, impurities, etc., and it is difficult to obtain uniform and fine particles with good reproducibility using this method. Therefore, fine powder with an average particle size of 0.1 to 5 μm can be obtained by crushing and classifying the copolymer particles, which can be easily obtained especially in the case of suspension polymerization, and have a size of several tens of microns to several hundred μm. The method is practical. Suitable methods for grinding the particles include, for example, jet mills, fluid energy mills, and ball mills. Among these, jet mills and fluid energy mills are particularly preferred. It goes without saying that two or more of these pulverization methods may be used in combination to pulverize in stages. In any case, the particles thus pulverized are sent to the next classification step as necessary in order to obtain particles of a constant particle size suitable for use in the present invention. Classification methods include, for example, a semi-free whirlpool method, a forced whirlpool method, a hydrocyclone method, and a centrifugation method, and any of these methods may be employed. Of course, the classification step may be omitted if fine particles with a practical particle size distribution can be obtained only by the pulverization step. By the method described above, it is possible to obtain a crosslinked polymer fine powder having an average particle size of 0.1 to 5 μm, which is necessary for the present invention. In the present invention, the crosslinked polymer fine powder used in combination with the precipitated particles must be contained in the polyester film in an amount of 0.001 to 4% by weight, preferably 0.01 to 0.5% by weight. When this amount is less than 0.001% by weight, there is no effect of improving wear resistance, and there is almost no effect of imparting slipperiness. On the other hand, 4% by weight
Even if it is used in excess of this amount, the effect of improving abrasion resistance and imparting slipperiness will no longer be exhibited, and on the contrary, transparency will be lacking and the filter life will be shortened. In the present invention, the crosslinked polymer fine powder is preferably added at any time during the polyester manufacturing process. If a film is formed by adding and mixing to chip-shaped or powdered polyester after polymerization and extruding it, the reaction time between the fine powder and the polyester is short, and the particles of the cross-linked polymer fine powder do not react sufficiently with the polyester. Therefore, when the affinity is not improved and a stretched film is made, voids are generated around the particles and they tend to peel off from the film surface due to simple abrasion. As described above, in the present invention, the polyester raw material, oligomer, or polyester and the crosslinked polymer fine powder are heated at a temperature of 200°C or higher for at least 4 hours to substantially complete the covalent bond between the crosslinked polymer fine powder and the polyester. It is necessary to react with the body. Therefore, in the present invention, the crosslinked polymer fine powder is preferably added before the middle of the polycondensation stage, particularly preferably during the transesterification reaction or at the start of the polycondensation reaction. However, among the crosslinked polymer fine powders, those having carboxyl groups deactivate the transesterification catalyst when added during the transesterification reaction, so they must be added after the transesterification reaction is substantially completed. On the other hand, in the case of a crosslinked polymer fine powder having an ester group, for example, there is no effect of such a catalyst poison and it is possible to keep it in contact with the polyester oligomer for a longer period of time, so it is rather preferable to add it during the transesterification reaction. Adopted as a condition. Of course, the purpose can be fully achieved by adding these various particles after the transesterification reaction is substantially completed and before the polycondensation reaction is started. As for the method of adding the crosslinked polymer fine powder to the polymer manufacturing process, it is preferable to add it as an ethylene glycol slurry. The appropriate slurry concentration is about 0.5 to 20% by weight. The present invention is characterized in that it uses a combination of inert substance particles precipitated in a reaction system and insoluble and infusible crosslinked polymer fine powder that is substantially covalently bonded to this polyester. The film can be manufactured, for example, by the following method. A method in which polyester containing precipitated inert material particles and polyester containing crosslinked polymer fine powder are separately manufactured and blended to form a film. A method of producing and forming a film of polyester containing precipitated inert particles and crosslinked polymer fine powder at the same time. In any of these cases, the film may be formed by diluting with another polyester, such as a particle-free polyester obtained through direct esterification of terephthalic acid and ethylene glycol, to the extent that the spirit of the present invention is not impaired. Of course you can do that. In any case, the polyester film of the present invention contains 0.01 to 0.6% by weight of inert material particles with an average particle size of 0.5 to 5μ precipitated in the reaction system, and 0.1 to 0.1% by weight of inert particles with an average particle size of 0.1 to 5μ, which are substantially covalently bonded to the polyester. It should contain 0.001-4% by weight of ~5μ insoluble, fully crosslinked polymer. In order to obtain such a film, a known film forming method is used, for example, polyester chips are typically melt-extruded into a film at 270 to 295°C, cooled to solidify at 50 to 70μ to form an amorphous sheet, and then processed vertically and horizontally. A method such as simultaneous biaxial stretching or simultaneous biaxial stretching and heat treatment at 160 to 240° C. (for example, the method described in Japanese Patent Publication No. 30-5639) can be employed. As mentioned above, the film of the present invention has a specific particle size,
A certain amount of precipitated particles is used in combination with a certain particle size and a certain amount of a certain cross-linked polymer, and as a result, there are disadvantages when combining conventionally used metal compounds, such as lack of transparency, shortened filter life, and the particles themselves. We were able to improve various aspects of peeling from the film, but
Furthermore, it was found to be effective in the following respects. That is, the film of the present invention is a film with little eluate into water. Many of the metal compounds conventionally used as particles in addition methods are more or less soluble in water.
On the other hand, the crosslinked polymer fine powder used in the present invention does not dissolve in water at all, and there is a significant difference between the two. Therefore, the film of the present invention can be effectively used for general purposes, and can also exhibit its characteristics as a packaging film, particularly by taking advantage of the fact that it is hygienic with a small amount of elution in water. Furthermore, one of the features of the film of the present invention is that even if the ends of the biaxially stretched film are used as recycled products,
One example is that the properties of the obtained film do not deteriorate. This is an undesirable characteristic in the case of a polyester film containing only precipitated particles. As detailed above, the film of the present invention contains precipitated particles of a specific particle size and amount and a specific particle size and amount of insoluble, infusible crosslinked polymer fine powder that is substantially covalently bonded to the polyester. The characteristics of the latter crosslinked polymer fine powder are that it is uniformly dispersed in polyester, so it does not generate coarse particles due to aggregation, and its strong bond with polyester prevents the formation of voids and film formation during stretching. The particles do not peel off from the surface, the slipperiness has the effect of imparting wear resistance, and the polyester component does not dissolve into water at all and can be recycled. Due to the synergistic effect of the combination, the film has various properties necessary for the film, and can be used in a wide range of applications such as magnetic tape, vapor deposition, capacitors, and packaging. EXAMPLES The present invention will be explained in more detail with reference to examples below, but the present invention is not limited to the following examples unless the gist of the invention is exceeded. The various physical properties were measured using the following methods. Average particle size: Obtained using a microscope. That is, the particles or the polyester containing the particles were sandwiched between cover glasses, and the maximum particle diameter was measured after taking a photograph. The average particle size refers to the particle size expressed by the diameter at the point where the weight fraction is 50% by calculating the weight distribution of the particle group having the maximum diameter. Sliding property: Represented by friction coefficient, friction coefficient is ASTM
The measurement was carried out in accordance with D-1894 using a method modified so that it could be measured using a tape-shaped sample. The size of the sample during measurement was 15 mm in width and 150 mm in length, and the tensile speed was 20 mm/min. Measurements are made at a temperature of 21±
The test was carried out in an atmosphere of 2°C and humidity of 65±5%. Film turbidity: according to ASTA D1003-61 method,
Measurement was performed using a Nippon Denshoku turbidity meter NDH-2A model. Quantitative method for determining the amount of precipitated particles: Add 1.0 g of 0-chlorophenol to 100 g of polyester chips or film, heat at 120°C for 3 hours, and then heat at 20,000G for 2 hours.
Centrifuge for hours and collect the resulting particles at 100°C.
Dry in vacuum. If a melting peak corresponding to the polymer is observed when the particles are measured by scanning differential calorimetry, 0-chlorophenol is added to the particles and the centrifugation operation is performed again. When the melting peak is no longer observed, the weight of the particles is measured and the weight ratio to the polyester film is calculated. Measurement of abrasion resistance: A constant load was applied to the film, the film was moved back and forth between rolls, and evaluation was made based on the amount of white powder generated after a certain period of time. The evaluation was divided into three ranks and the best one was given A. In addition, when additive particles were included in the film, the presence or absence of the particles in the white powder was confirmed by measuring the infrared absorption spectrum of the generated white powder in order to check whether the particles were peeled off. If exfoliated additive particles are present, they will move as the film travels in the actual process, causing various troubles, so it is desirable that there be no exfoliated particles. Measurement of elution amount: Pure water in a flask with an internal volume of 3000ml
2000ml and 25μ thick polyester film 3.5
g was taken and heated at 60°C for 30 minutes. After cooling for 30 minutes and removing the film, the aqueous solution was concentrated to about 10 ml using a rotary evaporator. Next, the concentrated solution was evaporated to dryness using a platinum plate, and the weight of the solid was measured using a precision balance, and the weight ratio to the polyester film was defined as the elution amount. Similar measurements were also performed using 4% acetic acid/pure water instead of pure water. Filter life test: 1500 with over area ^31.2cm2
When extruding molten polymer at 8.5Kg/hr using a mesh filter, the pressure at the filter inlet was
By measuring the extrusion amount until reaching 250 kg/cm ² , the extrusion amount was expressed as a relative value. The larger this value is, the more preferable it is. Note that "parts" in the Examples and Comparative Examples indicate "parts by weight." Example 1 [Production of crosslinked polymer fine powder] 100 parts of methyl methacrylate, divinylbenzene
A homogeneous solution of 20 parts of ethylvinylbenzene, 18 parts of ethylvinylbenzene, 1 part of benzoyl peroxide, 80 parts of toluene, and 15 parts of polystyrene was dispersed in 800 parts of water. Next, polymerization was carried out by heating at 75° C. for 15 hours with stirring under a nitrogen atmosphere. The average particle size of the obtained crosslinked polymer particles having ester groups was about 0.2 mm. The product was washed with demineralized water and extracted twice with 500 parts of toluene to remove small amounts of unreacted monomer, linear polymer and polystyrene. Next, the polymer granules were heated in an attritor for 1 hour.
By grinding with a sand grinder for 2 hours, a crosslinked polymer fine powder with an average particle size of 1.8 μm was obtained. [Manufacture of polyester] 100 parts of dimethyl terephthalate, 75 parts of ethylene glycol, and 0.10 parts of calcium acetate monohydrate were placed in a reactor and heated to raise the temperature to carry out a transesterification reaction. The reaction temperature was 160℃ at the start of the reaction.
After 2 hours, the temperature was increased to 200°C, and after another 2 hours, the temperature was increased to 230°C. After 4 hours, 0.03 part of antimony trioxide was added to the reaction mixture in which the transesterification reaction had substantially completed, and polymerization was carried out in accordance with a conventional method. That is, the temperature was gradually raised from 230°C to 280°C. On the other hand, the pressure was gradually reduced from normal pressure to a final value of 0.3 mmHg. After 4 hours, the polymer was discharged and made into chips. This polyester is referred to as (A). In the obtained polyester, countless calcium salts of polyester oligomers having an average particle size of about 4 μm were observed. When the amount of the precipitated particles was measured, it was found to be 0.30% by weight based on the polyester. On the other hand, polyester containing crosslinked polymer fine powder was produced by the following method. That is, 100 parts of dimethyl terephthalate, 70 parts of ethylene glycol, 0.09 parts of calcium acetate monohydrate, and 0.10 parts of the previously obtained fine polymer powder with an average particle size of 1.8 μm were added, and the process was repeated in the same manner as in the production of polyester (A). A transesterification reaction was carried out. Next, phosphoric acid is added to this transesterification product.
0.040 part of antimony trioxide and 0.04 part of antimony trioxide were added and polymerization was carried out according to a conventional method. After 4 hours, the reaction system was returned to normal pressure with nitrogen to discharge the polymer. Almost no precipitated particles were observed in this polymer, and only fine polymer powder was observed to be uniformly dispersed. This polyester is referred to as (B). [Production of polyester film] Polyester (A) and polyester (B) are blended at a ratio of 4:1, melted at 290°C, extruded through a T-shaped die, rapidly cooled, and then stretched 3.5 times in the longitudinal and transverse directions. After aging, heat treatment was performed to obtain a film with a thickness of 25 μm. The evaluation results for this film are shown in Table 1. Example 2 In the production of polyester (A) in Example 1, 0.09 parts of calcium acetate monohydrate and 0.095 parts of lithium acetate dihydrate were used instead of 0.10 parts of calcium acetate monohydrate, and trimethyl was used instead of 0.040 parts of phosphoric acid. Polyester (C) was obtained by carrying out exactly the same operation except that 0.17 parts of phosphate was used. Numerous precipitated particles with an average particle size of about 2 μm were observed in the obtained polyester, and the amount thereof was 0.30% by weight based on the polyester. On the other hand, polyester (D) was obtained in the same manner as in the production of polyester (B) except that no crosslinked polymer fine powder was added. In this polyester (D), there are of course various additive particles,
Almost no precipitated particles were observed, and the polyester contained substantially no particles. Next, polyester (C), polyester (B), and polyester (D) were blended in a ratio of 2:5:3, and a polyester film having a thickness of 25 μm was obtained in the same manner as in Example 1. The evaluation results for this film are shown in Table 1. Example 3 Weakly acidic cation exchange resin WK-10 (manufactured by Mitsubishi Chemical Industries, Ltd., methacrylic acid-divinylbenzene copolymer) was mixed with a diet mill (manufactured by Nippon Neumatics Co., Ltd.).
PJM100) to obtain an average particle size of 5 μm, and further finely divided using a sand grinder to obtain a crosslinked polymer fine powder having carboxyl groups with an average particle size of 2.2 μm. Next, in the production of polyester (B), the average particle size
Polyester ( E) was obtained. Next, add polyester (A) and polyester (E) to 2:
After blending into Example 3, the thickness was adjusted in the same manner as in Example 1.
A 25μ film was obtained. The evaluation results for this film are shown in Table 1. Example 4 After blending polyester (A), polyester (D), and polyester (E) in a ratio of 12:12:1, a film having a thickness of 25 μm was obtained in the same manner as in Example 1. The evaluation results for this film are shown in Table 1. Example 5 A test was conducted using the end portion of the film obtained during the film forming operation in Example 1 as a recycled product. That is, the ends of the film obtained in Example 1 were melted again and pelletized. Next, 4 of polyester (A) and polyester (B):
3 parts of these pellets were blended with 10 parts of the blend of Example 1 to obtain a film having a thickness of 25 μm in the same manner as in Example 1. The evaluation results for this film are shown in Table 1. Example 6 100 parts of dimethyl terephthalate, 75 parts of ethylene glycol, 0.07 part of calcium acetate monohydrate, and the crosslinked polymer fine powder with an average particle size of 1.8μ used in Example 1
A transesterification reaction was carried out in the same manner as in the production of polyester (A) by adding 0.05 part. Next, 0.05 part of terephthalic acid and 0.04 part of antimony trioxide were added to the product after the transesterification reaction, and polymerization was carried out according to a conventional method. After 4 hours, the reaction system was returned to normal pressure with nitrogen to discharge the polymer. In addition to the crosslinked polymer fine powder, precipitated particles with an average particle size of about 1 μm were found to be uniformly dispersed in this polyester (F). In order to determine the amount of precipitated particles, the same operation was performed without adding the crosslinked polymer fine powder.
The amount was 0.25% by weight based on the polyester. Next, using this polyester (F), a film having a thickness of 25 μm was obtained in the same manner as in Example 1. The evaluation results for this film are shown in Table 1. Comparative Example 1 A film with a thickness of 25 μm was obtained in the same manner as in Example 1 using only the polyester (A) in Example 1. The evaluation results for this film are shown in Table 1. Comparative Example 2 In the production of polyester (E) in Example 3, instead of 0.20 parts of polymer fine powder with an average particle size of 1.8μ,
Polyester (G) was obtained by carrying out exactly the same operation except that 0.20 part of 2.5μ calcium sulfate was used. Next, add polyester (A) and polyester (G) to 3:
A film having a thickness of 25 μm was obtained in the same manner as in Example 1. The evaluation results for this film are shown in Table 1. Comparative Example 3 A test was conducted using the end portion of the film obtained during the film forming operation in Comparative Example 1 as a recycled product. That is, the end portion of the film obtained in Comparative Example 1 was melted and pelletized again. Next, 5 parts of the pellets were blended with 10 parts of the polyester (A) used in Comparative Example 1, and a film having a thickness of 25 μm was obtained in the same manner as in Comparative Example 1. The evaluation results for this film are shown in Table 1. As is clear from the results in Table 1, the polyester film of the example takes advantage of the features of the precipitated particles and satisfies various properties depending on the film application. It is understood that this method has clearly superior properties compared to the combination method. 【table】

Claims (1)

[Claims] 1 0.01 to 0.6% by weight of inert material particles with an average particle size of 0.5 to 5μ precipitated in the reaction system and 0.001 to 0.6% of crosslinked polymer fine powder with an average particle size of 0.1 to 5μ that are substantially covalently bonded to the polyester. % by weight.