KR960002958B1 - Manufacturing method of polyester for film molding - Google Patents

Abstract

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Description

Manufacturing method of polyester for film molding

The present invention relates to a method for producing a polyester film molding polyester having excellent dispersibility of silica particles, and more particularly, to a cumylphenyl acetate during the polymerization process of a resin in which at least 80 mol% of the polyester resin is ethylene terephthalate. The present invention relates to a method for producing a polyester for film forming to improve the slip resistance and abrasion resistance of a final polyester film by adding dispersed spherical silica particles to form protrusions on the film surface.

In general, polyesters represented by polyethylene terephthalate are excellent in physical and chemical properties, and are molded into films to be used in various applications ranging from magnetic tapes, photographs, graphic arts, capacitors, and packaging.

However, in spite of its excellent properties, polyethylene terephthalate itself has poor slipperiness and abrasion resistance when contacted with a plurality of metal rolls during film forming, resulting in poor workability of the film forming process and processing step.

Slip and wear resistance of polyester film is a factor that greatly affects product quality as well as in the film manufacturing process and processing stage. If the slipperiness and wear resistance are poor, scratches and a large amount of friction and abrasion between the film surface and metal roll during processing Problems such as the occurrence of a percentage of.

In particular, when a magnetic layer is applied to the surface of a polyester film and used for magnetic tape, the magnetic tape and the head drum and the guide roll of the recording and reproducing apparatus are often in contact with the magnetic tape when accumulating or recording the magnetic tape. Damage to the film surface and generation of powder may adversely affect the magnetic signal such as dropout, and if it is used repeatedly for a long time, the friction coefficient increases and the running performance is deteriorated.

In order to improve the slip resistance and abrasion resistance of the polyester film, a method of providing projections on the surface of the polyester film to reduce the contact area between the film and the film and the roll is generally used. Internal particle methods for depositing inert particulates from components and external particle methods for adding inert particulate components during polyester production are known.

The internal particle method does not require grinding, powdering, etc., and the internally produced particles have good affinity with the polymer, and because the hardness of the produced particles is low, the wear resistance is excellent. have.

On the other hand, the external particle method adds inert inorganic particles such as calcium carbonate, calcium sulfate, barium sulfate, kaolin, silica, talc, titanium dioxide and the like during the polymerization or molding of the polyester so that the selection of the particle amount and particle size It is easy and can control the properties of the polymer and the state of the particles stably even in long-term operation, but this method is advantageous when coarse particles are produced by the aggregation of particles according to the type and particle size of the particles. There are many disadvantages such as dropouts.

In general, the larger the particles contained in the polyester, the better the sliding effect of the polyester film is. However, the polyester film containing the particles having a larger particle size for improving the slippery properties is used when used in precise fields such as magnetic recording media. Worsening of the product quality. In the case of a recent film for a magnetic recording medium, as the density of magnetic recording is required, it has to be miniaturized to the particles and the size added to the film.

However, the finer the particles are, the more the cohesive tendency due to the attraction between the particles increases, so that the number of coarse particles increases, so that a special particle dispersion method is desired.

On the other hand, when polymerizing a polyester for film by adding silica, which is one of the inert inorganic particles, serious agglomeration of silica causes a serious problem of increasing coarse particles in the polyester film.

When silica is added as an inert inorganic particle, in order to prevent agglomeration of fine particles, a method of improving dispersibility by blocking silanol groups on the surface of silica particles has been proposed, as shown in Japanese Patent Application Laid-Open No. 57-44623. There is no mention of the type or method of treatment.

Accordingly, it is an object of the present invention to provide a method for producing a polyester for film forming containing silica particles having excellent particle dispersibility. In order to achieve the above object as well as another easily expressed object in the present invention for the silica particles having an average particle diameter of 0.010 ~ 1.0μm when producing a polyester consisting of ethylene terephthalate of 80 mol% or more of the chemical structural repeat unit of the resin The silica for dispersing by adding 0.05-10 weight% of cumyl phenyl acetate ester represented by following formula (I) was administered in the polyester polymerization process, and the polyester for film molding was manufactured.

The present invention will be described in more detail as follows.

The aromatic polyester used in the present invention is preferably a copolymer of a dicarboxylic acid component composed of at least 80 mol% of terephthalic acid or its ester-forming derivative and a glycol component composed of at least 80 mol% of ethylene glycol. Copolymer components other than these components are 20 mol% or less of 2,6-naphthalenedicarboxylic acid, isophthalic acid, diphenylcarboxylic acid, diphenylmethane carboxylic acid, diphenyl ether carboxylic acid, diphenyl sulfone Dicarboxylic acid components such as dicarboxylic acid, diphenyl ketone dicarboxylic acid, anthracenedicarboxylic acid or ester-forming derivatives thereof and 20 mol% or less of trimethylene glycol, tetramethylene glycol, pentamethylene glycol, hexa Both alkylene glycol components having 2 to 10 carbon atoms such as methylene glycol or alicyclic diols such as cyclohexanedimethanol are possible.

In the present invention, silica is produced by hydrolysis of silicon tetrachloride in a flame of hydrogen and oxygen at a high temperature of 1000 ° C. or higher, and produced by acidification with sulfuric acid based on sodium silicate (ACIDULATION). Precipitated silica (CLECIPITATED SILICA) or cladular spherical silica prepared by hydrolysis of ethyl orthosilicate can be used, but precipitated silica or colloidal spherical silica containing a lot of silanol groups on the surface of the particles can be used. Is effective.

In the silica dispersion treatment method of the present invention, 5-30% by weight of silica having an average particle diameter of 0.010-1.0 μm is added to ethylene glycol, and 0.05-10% by weight of cumylphenyl acetate ester is added to the silica. If the amount of cumylphenyl acetate to silica is less than 0.05% by weight, the dispersibility of silica is not sufficiently exhibited. If the amount of cumylphenyl acetate is less than 0.05% by weight, the amount of cumylphenyl acetate is less than 0.05%. The color of the resulting polyester is changed.

If the silica dispersion treatment temperature is less than 40 ℃ do not mix well with ethylene glycol and cumyl phenyl acetate does not improve the silica dispersibility, it is economically disadvantageous if it exceeds 150 ℃. The mechanism of improving dispersibility of cumylphenyl acetate in the present invention is not clearly understood, but the silanol group is blocked by silanol group and cumylphenyl acetate ester which are hydroxyl groups present on the surface of silica particles, thereby reducing the hydrophilicity of the surface of silica particles. It is expected that the dispersibility of silica will be improved.

The silica-ethylene glycol slurry of the present invention is excellent in dispersibility even when added at any point in the esterification reaction or transesterification reaction during the polymerization of polyester.

The polyester resin of the present invention exhibits particularly excellent properties when forming films for magnetic recording media or packaging films.

The following examples and comparative examples clearly illustrate the present invention and do not limit the present invention.

The physical property evaluation method in this invention is as follows.

(1) intrinsic viscosity of polyester

It was measured at 25 ° C. using orthochlorophenol.

(2) Average particle diameter of silica particles

Carrier grids covered with a PARLODION FILM were immersed in a silica slurry, dried, and the average particle size was obtained by observing the diameter of the primary particles with a transmission electron microscope.

(3) dispersibility of particles

To produce a film of 15μm thick as observed with an optical microscope to measure the tank greater than the particle size of the particles in the measurement area of 1mm ² 5μm substituted atoms it was determined as follows.

Level 1: 1-3

Level 2: 4 ~ 7

Level 3: 8-11

Level 4: 11 or more

(4) surface roughness of film

Using a surface roughness meter (SE-3H manufactured by Kosaka Kengusho), the measurement was carried out five times under the following conditions, and the average value was determined to determine the centerline surface roughness (Ra).

Radius of stylus: 2μm

Measuring length: 1.0mm

Measuring Pressure: 45mg

Cutoff Value: 0.8mm

Example 1

10 parts of silica and 0.2 parts of cumylphenyl acetate ester having an average particle diameter of primary particles were added to 90 parts of ethylene glycol, and the mixture was stirred at high speed at 1000 rpm for 10 minutes using a homomixer. The reaction is stirred for 3 hours at.

100 parts of dimethyl terephthalate and 64 parts of ethylene glycol were added to a reaction tube equipped with a rectifying tower, followed by addition of 3 parts of a dispersed silica-ethylene glycol slurry, followed by 0.09 parts of calcium acetate as a transesterification catalyst, followed by a reaction tube temperature of 180 °. The transesterification was carried out at ˜240 ° C. After distillation of methanol was completed, 0.04 part of antimony trioxide and 0.05 part of trimethyl phosphates were added, and the polycondensation reaction was performed at the temperature of 240-290 degreeC under reduced pressure.

The polyethylene terephthalate having a viscosity of 0.63 obtained in the polycondensation reaction was dried at 175 ° C. for 3 hours and melted at an temperature of 290 ° C. in an extruder. The molten polyester was extruded through a slit die onto a rotating cooling drum to obtain an unstretched sheet having a thickness of 205 μm.

The unstretched sheet was stretched by 3.75 times the vertical magnification and 3.7 times the horizontal magnification by a conventional method and heat-set at 200 ° C. for 5 seconds to obtain a biaxially stretched polyester film having a thickness of 15 μm. As a result of evaluating the obtained film, it turned out that it is a polyester film excellent in the particle dispersibility whose centerline surface roughness of a film is 0.008 micrometer, and particle dispersibility is primary.

Comparative Example 1

A biaxially stretched polyester film was obtained in the same manner as in Example 1 except that cumylphenyl acetate ester was not added. As a result of the evaluation of the film, the centerline surface roughness of the film was 0.014 μm, and the dispersibility of the particles was fourth, and many coarse particles were observed.

Example 2

A biaxially stretched polyester film was obtained in the same manner as in Example 1 except that 10 parts of colloidal spherical silica having an average particle diameter of 0.1 μm and 0.1 part of cumylphenyl acetate acetate were added and dispersed for treatment. Evaluation results of the film The centerline surface roughness 0.010μm Particle dispersibility A polyester film having excellent primary particle dispersibility was obtained.

Comparative Example 2

A biaxially stretched polyester film was obtained in the same manner as in Example 2 except that cumylphenyl acetate ester was not added. As a result of evaluating the film, the surface roughness of the centerline of the film was 0.017 μm, and the dispersibility of the particles was third, and many coarse particles were observed.

Claims (1)

In the preparation of a polyester in which at least 80 mol% of the chemical structural repeating units are made of ethylene terephthalate, cumylphenyl acetate ester represented by the following formula (I) to silica particles having an average particle diameter of 0.010 to 1.0 μm, 0.05 to 10 A method for producing a polyester for film molding, comprising adding silica by weight and dispersing the silica at any time during the polyester polymerization step.