JPH0670167B2 - Polyester film - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyester film containing silica particles obtained by a specific method and having excellent dispersibility, transparency and running property.

[0002]

2. Description of the Related Art Polyester films represented by polyethylene terephthalate have excellent physical and chemical properties, and are therefore used as base films for graphic arts, displays, packaging materials and magnetic recording media. Widely used in fields such as capacitor derivatives.

However, when it is desired to manufacture a film that makes full use of its transparency, the film travels in terms of process passability in the manufacturing process, post-processing steps such as coating and vapor deposition, or handling of the product itself. However, conventionally, this has not always been sufficiently achieved. In many cases, this was due to friction and wear caused by the high speed contact between the film and the substrate.

It has hitherto been known that in order to improve the running property and abrasion resistance of a polyester film, the surface of the film should be appropriately roughened. And in order to achieve this, a method in which fine particles are present in the raw material polyester is adopted, and some of them have been put into practical use,
A high degree of satisfaction with these properties has not always been successful.

For example, when so-called precipitated particles are used as fine particles, which are produced from a catalyst residue during the production of polyester, it is difficult to control the amount of particles, the particle size, and prevent the formation of coarse particles. However, since the fine particles are easily broken, the running property and the wear resistance are poor, and the recycling is difficult. When inert inorganic compound particles are added to polyester such as calcium carbonate, titanium dioxide, calcium phosphate, which is another method called addition method, the particles are not broken or deformed by stretching, and the projections are relatively sharp. Therefore, the running property is improved, but since such particles have poor affinity with polyester, voids are generated around the particles during stretching, the transparency is significantly reduced, or the particles are easily separated from the film surface, A phenomenon such as generation of a white powder substance occurs.

As one of the addition methods, silica particles having a relatively good affinity for polyester are used (for example, JP-A-37-12150 and JP-A-53-45369).
The method described in Japanese Patent No. 6) is known. However,
As described in JP-A-43-23960, since silica particles have extremely poor dispersibility in polyester, agglomeration occurs during production of polyester, and when formed into a film, many coarse particles are formed on the surface of the film. There are protrusions,
The transparency of the film is reduced. Further, silica particles have a drawback that they reduce the polymerization rate during the production of polyester and the thermal stability of the obtained polymer. The reason for this is not clear, but it is considered to be due to the interaction between the silanol groups present on the surface of the silica particles and the metal compound as the polymerization catalyst, for example, the metal compound is partially trapped.

[0007]

The present inventors have found that the dispersibility,
As a result of repeated intensive studies to provide an excellent film that satisfies both traveling property and transparency at the same time, and can sufficiently satisfy various properties required as a film, by using a specific silica particle, The inventors have found that the problems can be solved and completed the present invention.

That is, the gist of the present invention is a particle obtained from silica particles containing 1 to 30 silanol groups / nm ² , wherein 30% or more of all silanol groups are calcium silanolates, and the average. A polyester film is characterized by containing 0.001 to 5% by weight of silica particles having a particle diameter of 0.1 to 5 μm.

The present invention will be described in more detail below. The polyester in the present invention means terephthalic acid, 2,6-
An aromatic dicarboxylic acid such as naphthalenedicarboxylic acid or an ester thereof and a polyester obtained by using ethylene glycol as a main starting material are mentioned, but other third component may be contained. In this case, as the dicarboxylic acid component, for example, one type such as isophthalic acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid, adipic acid, and sebacic acid can be used. As the glycol component, one or more of diethylene glycol, propylene glycol, butanediol, 1,4-cyclohexanedimethanol, neopentyl glycol and the like can be used. In any case, the polyester of the present invention refers to a polyester in which 80% or more of repeating structural units have ethylene terephthalate units or ethylene-2,6-naphthalate units.

The polyester film of the present invention means at least a uniaxially oriented polyester film using such polyester as a starting material, and a known method can be adopted as a method for producing the same. For example, after melt-extruding into a sheet form at 270 to 320 ° C., cooling and solidifying at 40 to 80 ° C. to form an amorphous sheet, at 80 to 130 ° C., an area ratio of 4 to 20 in the longitudinal and transverse directions.
Sequentially biaxially stretched or simultaneously stretched so that
Method of heat treatment at 0 to 250 ° C. (for example, Japanese Patent Publication Sho 30-5
The method described in Japanese Patent No. 639) can be used. When stretching in the machine and transverse directions, each may be stretched in one stage, or may be stretched in multiple stages or a heat treatment section for orientation relaxation may be provided between the multi-stage stretches, if necessary. Further, after biaxial stretching, it may be stretched again before being subjected to the heat treatment step of the next step. This re-stretching can be carried out in any of the longitudinal and lateral directions, or in both directions.

A feature of the present invention is that silica particles having a specific amount of silanol groups, which are calcium silanolates in 30% or more of the total silanol groups, are used as particles to be incorporated in the polyester film. is there. As a method for producing such particles, a so-called wet method, that is, a method using a medium containing water as a main component, for example, sodium silicate and calcium salts such as calcium hydroxide are reacted to first produce calcium silicate, Decomposes with mineral acid or carbon dioxide to synthesize particles containing silica as the main constituent.

The silica particles obtained by such a method are
Normally, 100~700m ² / g order of the specific surface area (BET
Method), and can be preferably used because it has stretching followability in polyester, and its silanol groups are about 1 to 30 / nm ² and are significantly larger than those of the gas phase method. . If such particles are added and polymerized in the polyester manufacturing process, the polymerization reaction will be delayed.

However, the inventors of the present invention can improve such a defect and further improve the dispersibility of the particles in the polyester by blocking the silanol groups with calcium at a certain ratio or more. I found a thing. That is, a method of ion-exchanging silanol groups of particles having the number of silanol groups of 1 to 30 / nm ² , preferably 5 to 15 / nm ² obtained by the above wet method in an aqueous calcium chloride solution is adopted. By doing so, the silanol group can be converted to calcium silanolate. In this case, a particle size suitable for use in the present invention,
The particles having the composition can be efficiently obtained. The number of silanol groups in the silica particles to be calcium silanolate is 1 /
When it is less than nm ² , the affinity with polyester is poor, which is not preferable. Further, when the number is 30 / nm ² or more, the dispersibility in polyester is poor, which is not preferable.

In the present invention, 3 of all silanol groups are included.
Silica particles in which 0% or more is converted to calcium silanolate are used. When the calcium silanolate conversion rate is less than 30%, the dispersibility of particles in polyester and the thermal stability are deteriorated, which is not preferable. The calcium silanolate conversion rate is preferably 40% or more. The average particle size of the silica particles to be incorporated into the polyester film of the present invention is 0.1 to
It is in the range of 5 μm, preferably 0.5 to 2 μm. When the average particle size is less than 0.1 μm, the running property and abrasion resistance of the film are insufficient, and when the average particle size exceeds 5 μm, the surface roughness of the film becomes too large, and the transparency of the film becomes poor. It is not preferable because it lowers.

The blending amount of silica particles in the polyester film of the present invention is in the range of 0.001 to 5% by weight, preferably 0.01 to 1% by weight. Compounding amount 0.00
If it is less than 1% by weight, the running property and abrasion resistance of the film are insufficient. Further, if the blending amount exceeds 5% by weight, the surface roughness becomes too large, which is not preferable. The method of blending the silica particles used in the present invention with the polyester film-forming raw material is
The method is not particularly limited, and a known method can be adopted. For example, the particles and the polyester chips can be directly blended, but dispersed in ethylene glycol which is a raw material of polyester, and as an ethylene glycol slurry, at any stage of the polyester production process, preferably after completion of the esterification or transesterification reaction. When the polycondensation reaction is carried out by adding the polycondensation reaction before the start of the polycondensation reaction, the effect of the present invention is maximized.

The silica particle dispersion slurry used in the present invention can be prepared by a conventionally known method. For example, silica particles and ethylene glycol can be dispersed and adjusted using a high-speed stirrer having a plurality of shearing blades parallel to the rotating direction of the stirring blade, a homomixer, an ultrasonic disperser, or the like. Further, the dispersed slurry is 1000 for the purpose of removing coarse particles and undispersed aggregated particles in the slurry.
It is desirable to filter with a filter of mesh or more.
In addition, if necessary, other particles such as kaolin, talc, calcium carbonate, aluminum oxide, or crosslinked polymer particles can be used in combination as long as the gist of the present invention is not impaired.

[0017]

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples without departing from the gist thereof. The measuring methods and definitions of various physical properties and characteristics in the present invention are as follows. In Examples and Comparative Examples, “part” means “part by weight”.

(1) Quantification of silanol group Silica particles were dried at 120 ° C. under reduced pressure for 3 hours, then reduced with lithium aluminum hydride in dioxane, and the amount of hydrogen generated was measured by gas chromatography to obtain silanol. The radix was calculated. The number of silanol groups of the calcium silanolated particles was determined by the same method. The calcium silanolate conversion rate was calculated from the following formula.

[0019]

[Equation 1]

(2) Calcium Element Content in Silica Particles Hydrofluoric acid was added to the silica particles to dissolve the silica particles, and the excess hydrofluoric acid was removed by heating. Then, a hydrochloric acid solution was added to the silica particles for quantification.

(3) Average Particle Size and Particle Size Distribution Centrifugal sedimentation type particle size distribution measuring device (SA-CP) manufactured by Shimadzu Corporation
Equivalent spherical distribution measured by type 3) 5
The diameter (particle size) of 0% was taken as the average particle size. (4) Intrinsic viscosity 1 g of polymer is phenol / tetrachloroethane = 50
Dissolve in 100 ml of mixed solvent of 50/50 (gravity ratio), 30.
It was measured at 0 ° C.

(5) Thermal Stability About 10 g of polymer was put into a glass test tube having an internal capacity of 50 ml, dried under high vacuum at 160 ° C. for 2 hours, and then recompressed to 100 mmHg with nitrogen gas to melt the glass test tube. After sealing 290
The heat treatment was performed at ℃ for 2 hours, the intrinsic viscosity before and after the heat treatment was measured, and the intrinsic viscosity retention rate was calculated from the following formula.

[0023]

[Equation 2]

The intrinsic viscosity retention rate after heat treatment at 290 ° C. for 2 hours was used as a measure of thermal stability.

(6) Travelability On a smooth glass plate, two films cut into a width of 15 mm and a length of 150 mm are stacked, and a rubber plate is placed on the film.
20mm / min when the pressure of two films is 2g / cm ^2.
The films were slid with each other to measure the frictional force, and the coefficient of friction at the point where the films were slid by 5 mm was determined as the dynamic coefficient of friction. The measurement was performed in an atmosphere having a temperature of 23 ° C. ± 1 ° C. and a humidity of 50% ± 5%.

(7) Wear characteristics The wear characteristics were evaluated by the amount of white powder generated. The film was run for 1000 m while contacting the fixed pin made of hard chrome, and the amount of worn white powder adhering to the fixed pin made of hard chrome of 6 mmφ was visually evaluated and divided by the ranks shown below.
The film speed was 13 m / min and the tension was about 20.
0 g, and the winding angle of the film around the pin was 135 °. Rank A: No adhesion Rank B: Small amount adhesion Rank C: Small amount (more than Rank B) adhesion Rank D: Extremely large adhesion (8) Number of coarse protrusions 10 mg sample is accurately weighed and covers 18 × 18 mm Scissor in glass, heat press at 280-290 ℃, diameter of about 10mm
Of the phase difference microscope (1
(00 times), particles having a maximum length of 10 μm or more were measured, and the number of coarse projections was counted. (9) Transparency According to JIS-K61714, the film haze was measured by Nippon Denshoku Industries Co., Ltd. sphere type turbidimeter NDH-20D.

Example 1 (Preparation of Slurry) Average particle size 0.85 μm, number of silanol groups 8.8 / nm
^When 120 parts of 0.5 wt% calcium chloride aqueous solution was added to 10 parts of the silica particles of No. ² and the silanol groups on the particle surface were ion-exchanged with calcium ions under stirring, the calcium silanolate conversion rate was 52.5%, calcium The content was 5.5% by weight. After removing the treated particles, 90 parts of ethylene glycol was added, and 10,000 rp was obtained with a homomixer (TK homomixer manufactured by Tokushu Kika Kogyo).
It was dispersed for m-60 minutes and filtered through a wire mesh filter of 1000 mesh to obtain an ethylene glycol slurry.

(Production of Polyester) 100 parts of dimethyl terephthalate, 60 parts of ethylene glycol and 0.09 part of magnesium acetate tetrahydrate are heated and heated, and methanol is distilled off to carry out an ester exchange reaction, and 4 hours after the reaction is started. The temperature was raised to 230 ° C., and the transesterification reaction was substantially completed. Next, after adding 3 parts of the above slurry, 0.04 part of ethyl acid phosphate was added, and further 0.04 part of antimony trioxide was added to carry out a polycondensation reaction. After 4 hours and 30 minutes, an intrinsic viscosity of 0.660 was obtained. Of polyethylene terephthalate was obtained. The obtained polyester is dried, melt-extruded at 290 ° C. to obtain an amorphous sheet, and then stretched 3.5 times at 90 ° C. in the longitudinal direction and 3.7 times at 110 ° C. in the transverse direction.
A heat treatment was performed at 3 ° C. for 3 seconds to obtain a film having a thickness of 15 μm, and its characteristics were evaluated.

Example 2 Example 1 was repeated except that silica particles having an average particle size of 1.25 μm and a silanol group number of 8.2 / nm ² were used.
A polycondensation reaction was carried out in the same manner as in, and after 4 hours and 25 minutes, polyethylene terephthalate having an intrinsic viscosity of 0.661 was obtained.
Using the obtained polyester, a film was obtained in the same manner as in Example 1 and its characteristics were evaluated.

Example 3 Silica particles having an average particle size of 1.25 μm and a silanol group number of 8.2 / nm ² were used in Example 1, and 0.5% by weight was used.
Example 1 except that 160 parts of the calcium chloride aqueous solution is used.
A polycondensation reaction was carried out in the same manner as above, and polyethylene terephthalate having an intrinsic viscosity of 0.659 was obtained in 4 hours and 20 minutes. Using the obtained polyester, a film was obtained in the same manner as in Example 1 and its characteristics were evaluated.

Comparative Example 1 The same as Example 1 except that silica particles having an average particle size of 0.85 μm and a silanol group number of 8.8 / nm ^{2 which} were not subjected to an ion exchange treatment with an aqueous calcium chloride solution were used. When the polycondensation reaction was carried out by using a polycondensation reaction, the polymerization rate in the latter stage of the reaction was slow, and it took 5 hours and 20 minutes to obtain polyethylene terephthalate having an intrinsic viscosity of 0.657. Using the obtained polyester, a film was obtained in the same manner as in Example 1 and its characteristics were evaluated.

Comparative Example 2 Average particle size of 1.25 μm without ion exchange treatment with calcium chloride aqueous solution, number of silanol groups of 8.2 / nm
^A polycondensation reaction was carried out in the same manner as in Example 1 except that the silica particles of ² were used, and it took 5 hours and 10 minutes to obtain polyethylene terephthalate having a slow polymerization rate in the latter stage of the reaction and an intrinsic viscosity of 0.658. Using the obtained polyester, a film was obtained in the same manner as in Example 1 and its characteristics were evaluated.

Comparative Example 3 In Example 1, silica particles having an average particle size of 1.25 μm and a silanol group number of 8.2 / nm ² were used, and 100 parts of a calcium chloride aqueous solution having a concentration of 0.1% by weight was used. , Silanolation was carried out. Then, using the obtained particles, a polycondensation reaction was carried out in the same manner as in Example 1. As a result, the polymerization rate in the latter stage of the reaction was slow and the intrinsic viscosity was 0.657.
It took 5 hours to obtain the polyethylene terephthalate. Using the obtained polyester, a film was obtained in the same manner as in Example 1 and its characteristics were evaluated.

The results obtained above are summarized in Table 1 below.

[0035]

[Table 1]

As shown in Table 1, the films of Examples 1 to 3 which are the categories of the present invention all have excellent dispersibility, thermal stability, transparency, running property and abrasion resistance, and for example, graphic arts, While extremely useful as a base film for displays and packaging, when the silica particles are not calcium silanolated as in Comparative Examples 1 to 3 or when the degree thereof is low, the polymerizability is poor, and the film is further reduced. In that case, the dispersibility of particles in the film, the thermal stability and the transparency are poor.

[0037]

The film of the present invention has a uniform surface, is excellent in thermal stability, running property and transparency, and can be applied to various uses, and its industrial value is high.

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Claims (1)

[Claims] 1. A particle obtained from silica particles containing 1 to 30 silanol groups / nm ² , wherein 30% or more of all silanol groups are calcium silanolates, and an average particle size of 0.1 to 0.1. 0.001 of 5 μm silica particles
A polyester film, characterized in that the polyester film contains -5% by weight.