JPH0376207B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a polyester film with excellent transparency and slipperiness. Polyethylene terephthalate stretched film has excellent mechanical properties, electrical properties, and dimensional stability, so it is useful as a material in a variety of fields such as electrical applications, decorative applications, packaging applications, and magnetic tape applications. However, as is well known in the art, if the coefficient of friction of polyester films is large, the films will not slide against each other, and if it is extremely bad, blocking will occur, making it difficult not only to handle the film but also to make it particularly difficult to wind it up. Conventionally, this objective has been achieved by adding inorganic or organic substances to the film, either singly or in combination, in order to lower the coefficient of friction of the film. However, with such a film, the effect is small when the amount added is small, and when a large amount is added, the transparency and turbidity of the film decrease rapidly. There has never been a film that significantly lowers the coefficient of friction. Furthermore, even if the same amount of the same additive is added to polyester, the rate of decrease in the friction coefficient greatly depends on the heat treatment conditions, and the greater the heat coverage history, the greater the rate of decrease. A method has been proposed to obtain a film with excellent lubricity and transparency by adding siloxane, etc. However, as the amount of polyorganosiloxane added increases, the lubricity becomes easier, but on the contrary, the transparency of the film does not decrease. Moreover, mechanical properties such as dimensional stability and Young's modulus also tend to deteriorate.Furthermore, there is a method of knurling before winding. Conventional manufacturing methods have had various drawbacks, such as the fact that In order to solve the above problem, the present inventors conducted extensive research and created a film obtained from polyester polymerized using a specific catalyst by adding a specific polyester copolymer that is insoluble in water to water together with a water-soluble organic compound. By dispersing and further laminating a coating agent containing inorganic particles by an in-line coating method, the film can be recycled, and the coating is transparent and has improved slipperiness with good explosion-proof stability in the coating process. A method for producing a polyester film is provided. That is, the present invention is a molded plate having a thickness of 4 mm that is polymerized using germanium as the main catalyst, substantially free of external lubricants, and injection molded in a mold cooled with a refrigerant at a temperature of 10°C ± 1°C. At least one side of an unstretched polyester film or a uniaxially oriented polyester film obtained by melt-extruding a polyester having a valance of 20% or less (A) contains 0.5 to 15 mol% of a sulfonic acid metal base in the total dicarboxylic acid component. A polyester copolymer obtained by stirring a polyester copolymer having a secondary transition point of 50°C or higher in excess hot water of 80°C for 24 hours, which contains a mixed dicarboxylic acid containing a dicarboxylic acid having a polyester as the dicarboxylic acid component of the polyester. A water-insoluble polyester copolymer with a weight loss of 5% by weight or less (B) A water-soluble organic solvent with a boiling point of 60 to 200°C (C) Water and (D) Inorganic particles, and each of the above contains (A) /(B)=100/20~5000 (B)/(C)=100/50~10000 (A)/(D)=100000/5~300. This is a method for producing a transparent slippery film, which is characterized in that after coating, the coated film is further stretched at least uniaxially. The polyester used in this invention uses germanium dioxide as the main catalyst, contains substantially no external lubricant, and has a temperature of 10°C.
Polyester that exhibits a haze value of 20% or less on a 4 mm thick molded plate that is injection molded in a mold cooled with a refrigerant at ±1°C. In detail, there are many catalysts used in the production of polyester, such as polyethylene terephthalate, such as calcium, antimony, magnesium, manganese, and germanium, but germanium is the most suitable for obtaining transparent polyester resin, and this As such a manufacturing method, the methods described in Japanese Patent Publication No. 49-1160, Japanese Patent Publication No. 47-19419, etc. are suitable. Naturally, the addition of external lubricants should be avoided as it reduces transparency; however, in fluorescent X-ray analysis, etc., it is possible to detect trace amounts of external lubricants as if they were present even though they were not intentionally added. Therefore, the expression "substantially free" here means that the amount detected by fluorescent X-ray analysis is less than the accuracy of analysis of various external lubricants. For example, a method using germanium dioxide is to dissolve GeO ₂ in ethylene glycol containing a certain amount of a specific basic substance and reflux it at the boiling point of ethylene glycol at 197°C. A clear solution can be obtained in about 30 minutes. After the transesterification reaction is completed, the above solution is added in a polycondensation apparatus, the temperature is gradually raised, and the polycondensation reaction is carried out at 280°C to 290°C under high vacuum. The above characteristics and basic substances are
Compounds of Ca, Sr, Ba, Ti, Pb, complex salts of these metals, lower fatty acid salts such as propionate, carbonates, inorganic weak acid salts such as borates, alkoxides,
Among oxide hydroxide compounds, it dissolves in ethylene glycol and exhibits basicity. However, the method is not limited to these methods. The polyester copolymer A contained in the aqueous dispersion used in this invention is a dicarboxylic acid mixture of 0.5 to 15 mol% of a dicarboxylic acid containing a sulfonic acid metal base and 85 to 99.5 mol% of a dicarboxylic acid containing no sulfonic acid metal base. It is a substantially water-insoluble polyester copolymer obtained by reacting an acid with a polyol component. Substantially water-insoluble means that the polyester copolymer does not dissipate in hot water even if the polyester copolymer is stirred in hot water at 80°C, and specifically, the polyester copolymer does not dissipate in hot water. of 80
The polyester copolymer has a weight loss of 5% by weight or less after being stirred in hot water at °C for 24 hours. Examples of the above-mentioned sulfonic acid metal group-containing dicarboxylic acids include metals such as sulfoterephthalic acid, 5-sulfoisophthalic acid, 4-sulfonaphthalic acid, 4-sulfonaphthalene-2,7-dicarboxylic acid, and 5[4-sulfophenoxy]isophthalic acid. Among these salts, 5-sodium sulfoisophthalic acid and sodium sulfoterephthalic acid are particularly preferred. These sulfonic acid metal base-containing dicarboxylic acid components are 0.5 to 15% of the total dicarboxylic acid components.
If it exceeds 15 mol%, the water dispersibility will improve, but the water resistance of the polyester copolymer will be significantly reduced, and if it is less than 0.5 mol%, the water dispersibility will decrease significantly. The dispersibility of the polyester copolymer in water varies depending on the copolymer composition, the type and blending ratio of the water-soluble organic compound, etc., but the above dicarboxylic acid containing a sulfonic acid metal group can be used as long as it does not impair the dispersibility in water. , a small amount is preferred. As the dicarboxylic acid containing no sulfonic acid metal base, aromatic, aliphatic, and alicyclic dicarboxylic acids can be used. Aromatic dicarboxylic acids include terephthalic acid, isophthalic acid, orthophthalic acid,
Examples include 2,6-naphthalene dicarboxylic acid. It is preferable that these aromatic dicarboxylic acids account for 40 mol% or more of the total dicarboxylic acid components, and if it is less than 40 mol%, the mechanical strength and water resistance of the polyester copolymer will decrease. Aliphatic and alicyclic dicarboxylic acids include succinic acid, adipic acid, sebacic acid, 1,3-cyclopentanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid,
1,3-cyclohexanedicarboxylic acid, 1,4-
Examples include cyclohexanedicarboxylic acid.
When these non-aromatic dicarboxylic acid components are added,
Although adhesive performance may be improved in some cases, it generally reduces the mechanical strength and water resistance of the polyester copolymer. As the polyol component to be reacted with the above mixed dicarboxylic acid, there are diols whose main component is aliphatic glycol having 2 to 8 carbon atoms or alicyclic glycol having 6 to 12 carbon atoms, and specifically, ethylene glycol , 1,2-propylene glycol,
1,3-propanediol, 1,4-butanediol, neopentyl glycol, 1,6-hexanediol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,
These include 4-cyclohexanedimethanol, p-xylene glycol, diethylene glycol, and triethylene glycol. Examples of polyethers include polyethylene glycol, polypropylene glycol, and polytetramethylene glycol, but they must be copolymerized so that the Tg is 50°C or higher. Polyester copolymers are obtained by conventional melt polycondensation. In other words, there is a direct esterification method in which the above dicarboxylic acid component and glycol component are directly reacted, water is distilled off and esterified, and then polycondensation is performed, or the dimethyl ester of the above dicarboxylic acid component and the glycol component are reacted to form methyl alcohol. It can be obtained by a transesterification method, etc., which involves distilling off, transesterifying, and then polycondensing it. In addition, solution polycondensation, interfacial polycondensation, etc. may also be used, and the polyester copolymer of the present invention is not limited by the polycondensation method. In order to obtain the aqueous dispersion of the polyester copolymer described above, it is necessary to disperse it in water together with a water-soluble organic compound. For example, the above polyester copolymer and a water-soluble organic compound are mixed in advance at 50 to 200°C, and water is added to this mixture and dispersed by stirring, or conversely, the mixture is added to water and stirred to disperse. method, or coexistence of polyester copolymer, water-soluble organic compound, and water for 40~
There is a method of stirring at 120℃. In the present invention, the water-soluble organic solvent is heated at 20°C.
An organic compound having a solubility in water of 20 g or more, specifically aliphatic and alicyclic alcohols, ethers, esters, and ketone compounds, such as monovalent compounds such as methanol, ethanol, isopropanol, and n-butanol. alcohol,
These include glycols such as ethylene glycol and propylene glycol, glycol derivatives such as methyl cellosolve, ethyl cellosolve, and n-butyl cellosolve, ethers such as dioxane and tetrahydrofuran, esters such as ethyl acetate, and ketones such as methyl ethyl ketone. These water-soluble organic compounds can be used alone or in combination of two or more. Among the above compounds, butyl cellosolve and ethyl cellosolve are preferred in terms of dispersibility in water and coatability on films. The weight ratio of the above (A) polyester copolymer, (B) water-soluble organic compound, and (C) water is (A)/(B)=100/20-5000 (B)/(C)=100 It is important to satisfy /50 to 10,000. Compared to polyester copolymers, (A)/(B) has less water-soluble organic compounds.
When it exceeds 100 to 20, the dispersibility of the aqueous dispersion decreases. In this case, dispersibility can be assisted by adding a surfactant, but
If the amount of surfactant is too large, adhesiveness and water resistance will decrease. Conversely, if (A)/(B) is less than 100/5000, or (B)/(C) exceeds 100/50, the amount of water-soluble organic compounds in the aqueous dispersion will increase, making it difficult to perform in-line coating. There is a risk of explosion due to the solvent, and therefore explosion-proof measures must be taken.Furthermore, it is necessary to consider recovery of the compound as it causes environmental pollution and increases costs. If (B)/(C) is less than 100/10000,
The surface tension of the aqueous dispersion increases, the wettability to the film decreases, and coating spots are more likely to occur. In this case, the wettability can be improved by adding a surfactant, but if the amount of the surfactant is too large, the adhesiveness and water resistance will decrease as described above. Furthermore, the (D) inorganic particles added to this dispersion include chalk, chiyolk, heavy carbon, light carbon, ultrafine carbon, basic magnesium carbonate, dolomite special calcium carbonate kaolin, calcined clay, and birofi. Light, bentonite, serisalite, zeolite, nephelin sinite, talc, attabuldianite, synthetic aluminum silicate, synthetic calcium silicate, diatomaceous earth, finely divided silicic acid containing silica powder, anhydrous finely divided silicic acid, aluminum hydroxide, barite, precipitated barium sulfate, natural There are gypsum, gypsum, calcium sulfite, and the like, and any of them may be used in terms of transparency and slipperiness, but natural and synthetic silicic acid products are particularly preferred. It is preferable to use particles with a particle size of 0.01μ to 10μ. If the particle size is 0.01 μm or less, a large amount must be used, and if the particle size is 10 μm or more, coarse projections will occur and the slipperiness will deteriorate. The amount of (D) to be used in relation to (A) is preferably a weight ratio of (A)/(D)=100000/5 to 300.
Preferably (A)/(D)=1000/20-100. The polyester film to which the aqueous dispersion of polyester resin is applied is an unstretched film obtained by melt-extruding the polyester film, or a uniaxially stretched film. Coating on a biaxially stretched film is not preferred because it is difficult to coat uniformly because the film is wide and the film travels at a high speed. The amount of the aqueous dispersion applied to the polyester film is 0.01 to 5 g/m ² of the polyester copolymer based on the biaxially stretched film.
If the coating amount is less than 0.01g/ ^m2 , the ability to fix inorganic particles will be weak and the durability will be poor5.0
If more than g/m ² is applied, the slipperiness will worsen. The polyester film obtained by the method described above has excellent transparency and slipperiness. In addition, by subjecting the polyester film to a corona discharge treatment before applying the aqueous dispersion of the polyester resin described above, the applicability of the aqueous dispersion is improved and the distance between the polyester film and the polyester copolymer coating film is improved. Adhesive strength is improved. In addition, the wettability and adhesion of the film surface can be improved by subjecting the polyester copolymer layer after inline coating or biaxial stretching to corona discharge treatment, corona discharge treatment under a nitrogen atmosphere, ultraviolet irradiation treatment, etc. can be done. The coated polyester film produced by the above method is used as a base film for magnetic tapes, a base film for label stickers, a booth film for chemical mats, a film for overhead projectors, a film for food packaging, and films for other uses. be done. Examples of the present invention will be described below. In the examples, parts and % are based on weight. Example 1 (1) Production of transparent polyethylene terephthalate Lead hydroxide in 200ml of ethylene glycol
PbO・Pb(OH) ₂ 2.2g (Pb0.95×10 ^-2 mol) was dissolved, and GeO ₂ 2.0g (1.9×10 ^-2 mol) was added to this solution at the boiling point of ethylene glycol at 197℃. A clear solution was obtained in about 30 minutes upon heating to reflux. Next, polyethylene terephthalate was produced using this solution as a polycondensation catalyst. 620 parts of dimethyl terephthalate, 480 parts of ethylene glycol, zinc acetate as transesterification catalyst
Add 0.036 parts of Zn(OAc) 2.2H _{2 O} to a transesterification reactor, and conduct the transesterification reaction from 150℃ to 230℃.
It took 120 minutes to complete the distillation of methanol. Next, the contents were transferred to a polycondensation apparatus, and the above catalyst solution was added as a polycondensation catalyst.
Add 2.7 parts, gradually raise the temperature and reduce the pressure.
Polycondensation reaction was carried out at 280℃ for 1 hour under high vacuum of 0.5mmHg for 25 minutes, and the resulting polymer had an intrinsic viscosity of 0.63, a melting point of 262℃, and a temperature of 10℃±
The haze value of a 4 mm thick molded plate injection molded using a mold cooled with a 1°C refrigerant was 4% or less. (2) Production of aqueous dispersion of polyester copolymer 117 parts of dimethyl terephthalate (49 mol%),
Dimethyl isophthalate 117 parts (49 mol%), ethylene glycol 103 parts (50 mol%), diethylene glycol 58 parts (50 mol%), zinc acetate 0.08
40 parts and 0.08 parts of antimony trioxide in a reaction vessel.
The temperature was raised to ~220°C to carry out the transesterification reaction for 3 hours, and then 9 parts (2 mol%) of 5-sodium sulfoisophthalic acid was added and the mixture was heated at 220 to 260°C for 1 hour.
The esterification reaction was carried out for a period of time, and further under reduced pressure (10~
A polyester copolymer having an average molecular weight of 18,000 and a softening point of 140°C was obtained by carrying out a polycondensation reaction at 0.2 mmHg) for 2 hours. 300 parts of this polyester copolymer and 140 parts of n-butyl cellosolve were mixed in a container at 150 parts
Stir at ~170℃ for about 3 hours to obtain a homogeneous and viscous melt. 560 parts of water is gradually added to this melt, and after about 1 hour, a uniform pale white solid content is obtained.
Obtain a 30% aqueous dispersion, and add thyroid to this.
150 was added and mixed at 500 ppm to the polyester copolymer, and diluted by adding 4,500 parts of water and 4,500 parts of ethyl alcohol to obtain a coating liquid with a solid content concentration of 3%. (3) Production of inline coated film The polyethylene terephthalate produced in (1) is
Melt extrusion at 280-300℃ and cooling with a cooling roll at 15℃ to obtain an unstretched film with a thickness of 1000 microns.This unstretched film is rolled 3.5 times in the longitudinal direction between a pair of rolls at different circumferential speeds at 85℃. Stretch it, apply the above coating solution using an air knife method, dry it with hot air at 70℃, and then apply it laterally at 98℃ using a tenter.
It was stretched 3.5 times and further heat-set at 200 to 210°C to obtain a biaxially stretched coated polyester film with a thickness of 100 microns. Example 2-3 When applying the aqueous dispersion using the air knife method in Example 1 above, the air pressure was adjusted to change the amount of the inorganic particle-containing polyester copolymer applied as shown in Table 1. A biaxially stretched film was obtained in the same manner as in Example 1 except for this. Examples 4 to 5 A biaxially stretched coated polyester film was obtained in the same manner as in Example 1, except that the copolymer components of the polyester copolymer in the aqueous dispersion were changed as shown in Table 1. Ta. Comparative Example 1 A coated polyester film was obtained in the same manner as in Example 1, except that the base range for polyester film was polymerized using a catalyst mainly containing an antimony compound. Comparative Examples 2 and 3 Polyesters prepared by adding 20 mol% of 5-sodium sulfoisophthalic acid based on the total dicarboxylic acids in Example 1 and changing the Tg by changing the amount of dicarboxylic acid components as shown in Table 1. A coated polyester film was obtained in the same manner as in Example 1 except that an aqueous dispersion of the copolymer was used. Comparative Examples 4 to 6 In Example 1, the added amount of Thyroid 150 was changed and Thyroid 620 with a large particle size
A biaxially stretched coated polyester film was obtained in the same manner as in Example 1, except that the following was added instead of Thyroid 150. In the table, TPA is equivalent to terephthalic acid, IPA is equivalent to isophthalic acid, NSI is 5-sodium sulfoisophthalic acid, AA is adipic acid, EG is ethylene glycol, DEG is diethylene glycol, NPG
is neopentyl glycol. Water-insoluble means that the polyester copolymer has an excess of 80%
The weight loss rate (%) of the polyester copolymer was measured after being stirred in hot water for 24 hours.

【table】

【table】

[Table] In Table 2, haze was measured using a haze meter manufactured by Nippon Seimitsu Kogaku Co., Ltd. according to JIS K 6714. The friction coefficient is a value measured on both coated and uncoated surfaces using Tensilon manufactured by Toyo Seiki Co., Ltd. in accordance with ASTM-1894. Blocking property was tested by cutting the coated and uncoated surfaces into 8 x 12 cm pieces, sandwiching them between two silicone rubber sheets, sandwiching them between glass plates, and applying a 2 kg load from the top of the glass plates. Multiply this at 40℃, 8
%RH for 24 hours, then remove the film and visually judge the blocking condition between the films. 5% or less of the blocking area is ○, 5 to 20% is △, and 20% or more is ×. Indicated. From Table 2 above, compared to this example, the haze was worse when antimony was the main catalyst during polyester base resin polymerization (Comparative Example 1) and when a large amount of inorganic particles were added (Comparative Example 5). In addition, when the amount of inorganic particles is extremely small (Comparative Example 4), when the average particle size is large (Comparative Example 6), when only polyester copolymer is applied (Comparative Example 7), and when there is no application (Comparative Example 8), slipping properties are poor.
Furthermore, as a dicarboxylic acid containing 20 mol% of 5-sodium sulfoisophthalic acid and a Tg of 15°C, the adipic acid copolymer is easily blocked. As described above, it can be seen that Comparative Examples 1 to 8 are polyester films that cannot be put to practical use, whereas those produced by the method of the present invention have good characteristics.

Claims (1)

[Claims] 1. Polymerized using germanium as the main catalyst, substantially free of external lubricants and at a temperature of 10°C.
At least an unstretched polyester film or a uniaxially stretched polyester film obtained by melt extruding a polyester having a haze value of 20% or less on a molded plate with a thickness of 4 mm injection molded in a mold cooled with a refrigerant at ±1°C. On one side: (A) A polyester with a secondary transition point of 50°C or higher whose dicarboxylic acid component is a mixed dicarboxylic acid containing a dicarboxylic acid having 0.5 to 15 mol% of sulfonic acid metal base in the total dicarboxylic acid component. Water-insoluble polyester copolymer (B) in which the weight loss of the polyester copolymer after stirring the polymer in excess 80°C hot water for 24 hours is 5% by weight or less Water-soluble organic solvent with a boiling point of 60 to 200°C (C) contains water and (D) inorganic particles, and each of the above (A)/(B)=100/20~5000 (B)/(C)=100/50~10000 (A)/(D A method for producing a transparent slippery film, which comprises applying an aqueous dispersion of polyester resin in a weight ratio of )=100000/5 to 300, and then further stretching the coated film at least uniaxially. [However, a water-soluble organic solvent is an organic compound having a solubility in water of 20° C. 1 of 20 g or more, and an inorganic particle having a particle size of 0.01 to 10 μm. 2. The method for producing a transparent, slippery polyester film according to claim 1, wherein the polyester is polyethylene terephthalate. 3. The method for producing a transparent slippery polyester film according to claim 1, wherein germanium in the polyester polymerization catalyst is germanium dioxide.