JP3111492B2 - 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 properties.

[0002]

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

[0003] However, in order to produce a film that makes full use of its transparency, it is necessary to improve the processability in the production process, the post-processing process such as coating and vapor deposition, or the handling of the product itself. Although running performance is particularly required, this has not always been sufficiently achieved. In many cases, this was caused by friction and abrasion caused by the high-speed contact between the film and the substrate.

Heretofore, it has been known that in order to improve the running property and abrasion resistance of a polyester film, the surface of the film may be appropriately roughened. And in order to achieve this, a method in which fine particles are present in the raw material polyester has been adopted, and although some methods have been put to practical use,
Highly satisfying these properties has not always been successful.

For example, in the case of using so-called precipitated particles produced from catalyst residues or the like during the production of polyester as fine particles, it is difficult to control the amount and diameter of the particles and to prevent the generation of coarse particles. Since the fine particles are easily broken, the running property and the abrasion resistance are inferior, and further, it is difficult to recycle. In the case of adding inorganic compound particles that are inert to polyesters such as calcium carbonate, titanium dioxide, and calcium phosphate, which is another method called the addition method, the particles are not broken or deformed by stretching, and the projections are relatively steep. To improve the running property, but such particles have poor affinity for polyester, so voids are generated around the particles during stretching, the transparency is significantly reduced, and the particles are easily detached from the film surface, Phenomena such as formation of white powdery substances occur.

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

[0007]

Means for Solving the Problems The present inventors have proposed dispersibility,
At the same time highly satisfying runnability and transparency, as a result of intensive studies to provide an excellent film that can sufficiently satisfy various properties required as a film, by using certain silica particles, The inventors have found that the problem can be solved, and have completed the present invention.

That is, the gist of the present invention is a particle obtained from silica particles containing 5 to 30 silanol groups / nm ² , wherein 30 to 70% of all silanol groups are blocked by a silane coupling agent treatment. Average particle size
A polyester film containing 1 to 5 μm of silica particles in an amount of 0.001 to 5% by weight.

Hereinafter, the present invention will be described in more detail. The polyester referred to in the present invention is terephthalic acid, 2,6-
It refers to an aromatic dicarboxylic acid such as naphthalenedicarboxylic acid or an ester thereof and a polyester obtained using ethylene glycol as a main starting material, but may contain other third components. In this case, as the dicarboxylic acid component, for example, isophthalic acid, terephthalic acid,
One of 2,6-naphthalenedicarboxylic acid, adipic acid, sebacic acid and the like can be used. Further, 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 the repeating structural units have an ethylene terephthalate unit or an ethylene-2,6-naphthalate unit.

The polyester film of the present invention refers to at least a uniaxially oriented polyester film using such a polyester as a starting material, and a known method can be employed for producing the polyester film. For example, after being melt-extruded into a sheet at 270 to 320 ° C., solidified by cooling at 40 to 80 ° C. to form an amorphous sheet, and then at 80 to 130 ° C. in an area magnification of 4 to 20 in the vertical and horizontal directions.
Biaxially or simultaneously at the same time so that
A method of heat treatment at 0 to 250 ° C (for example, Japanese Patent Publication No. 30-5)
No. 639). When stretching in the vertical and horizontal directions, stretching may be performed in one step, or if necessary, stretching may be performed in multiple steps, or a heat treatment section for relaxing orientation may be provided between the multiple steps. After the biaxial stretching, the film may be stretched again before being subjected to the next heat treatment step. This re-stretching may be performed in any of the vertical and horizontal directions, or may be performed in both directions.

A feature of the present invention is that the particles to be incorporated into the polyester film are 30 to 70% of the total silanol groups obtained from silica particles having a specific amount of silanol groups.
Is that silica particles blocked with a silane coupling agent are used. As a method for producing such particles, a so-called wet method, that is, a method using a medium mainly composed of water can be used. For example, sodium silicate is reacted with a calcium salt such as calcium hydroxide to first generate calcium silicate. After that, the particles are decomposed with a mineral acid or carbon dioxide gas to synthesize particles containing silica as a main component.

The silica particles obtained by such a method are as follows:
Usually, a specific surface area (BET) of about 100 to 700 m ² / g
Method), which is preferably a porous silica particle having a stretch-following property in polyester and can be preferably used, but its silanol group is about 1 to 30 / nm ² , which is much larger than that of the gas phase method. . If such particles are added in the polyester production step and a polymerization reaction is performed, the polymerization reaction is delayed.

However, the inventors of the present invention have been able to improve the disadvantage by blocking silanol groups by a silane coupling agent treatment at a certain ratio or more, and to improve the dispersibility of particles in polyester. Also found that it could be improved. The silane coupling agent used in the present invention generally has a chemical formula of YRSix ₃ (Y
Is an organic functional group such as a vinyl group, a methacryl group, an epoxy group, or an amino group, R is an alkyl group, Si is silicon, and X is a hydrolyzable group such as a chloro group, an alkoxy group, or an acetoxy group.) Such as vinyltriethoxysilane, vinyltrichlorosilane, γ-methacryloxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-aminopropyltriethoxysilane, and the like. It is not limited.

In the treatment with the silane coupling agent, usually 0.1 to 10% by weight of the silane coupling agent is dispersed in water or alcohol with respect to the silica particles, and if necessary, heated and stirred. Thereby, silanol groups of the silica particles can be blocked. In the present invention, 30 to 70% of the total silanol groups, preferably 4%
Silica particles having 0 to 60% blocked with a silane coupling agent are used. If the blocking ratio is less than 30%, the dispersibility and thermal stability of the particles in the polyester are poor, which is not preferable. If the sealing ratio exceeds 70%, the compatibility between the silica particles and ethylene glycol is poor, and it is difficult to mix the silica particles with the polyester as an ethylene glycol slurry.

The number of silanol groups on the surface of the silica particles before silanolization is 5 to 30 / nm ² , preferably 5 to 30 / nm ² .
The range is 15 / nm ² . 5 silanol groups /
If it is less than ² nm, it will not disperse in water or alcohol, so that inconvenience will occur when silanol groups are blocked. On the other hand, when the number of silanol groups exceeds 30 / nm ² , the dispersibility in water or alcohol deteriorates.

The average particle size of the silica particles blended in the polyester film of the present invention is in the range of 0.1 to 5 μm, preferably 0.5 to 2 μm. If the average particle size is less than 0.1 μm, the running properties and abrasion resistance of the film are insufficient,
On the other hand, if the average particle size exceeds 5 μm, the surface roughness of the film becomes too large, and the transparency of the film is undesirably reduced.

The compounding 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. 0.00%
If it is less than 1% by weight, the running property and abrasion resistance of the film are insufficient. On the other hand, if the amount exceeds 5% by weight, the surface roughness becomes too large, which is not preferable. Incidentally, the method of blending the silica particles used in the present invention with the polyester of the film forming raw material,
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 they can be dispersed in ethylene glycol as a raw material of the 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 at a stage before the start of the polycondensation reaction, the effect of the present invention is particularly maximized.

The dispersion slurry of silica particles used in the present invention can be prepared by a conventionally known method. For example, the dispersion of silica particles and ethylene glycol can be adjusted using a high-speed stirrer having a plurality of shearing blades parallel to the rotation direction of the stirring blades, a homomixer, an ultrasonic disperser, or the like. Further, the dispersed slurry is used for removing coarse particles and undispersed aggregated particles in the slurry.
It is desirable to filter with a filter of mesh or more.

Further, 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. .

[0020]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the scope of the invention. The methods and definitions for measuring various physical properties and properties in the present invention are as follows. In the examples and comparative examples, “parts” means “parts by weight”.

(1) Determination of Silanol Group Silica particles were dried at 120 ° C. under reduced pressure for 3 hours, reduced with lithium aluminum hydride in dioxane, and the amount of generated hydrogen was measured by gas chromatography. The radix was calculated. The number of silanol groups was determined for the calcium silanolated particles by the same method. The silanol blocking ratio was calculated from the following equation.

[0022]

(Equation 1)

(2) Average particle size and particle size distribution Centrifugal sedimentation type particle size distribution analyzer (SA-CP manufactured by Shimadzu Corporation)
Integrated volume fraction 5 in equivalent spherical distribution measured by type 3)
The diameter (particle size) of 0% was defined as the average particle size.

(3) Intrinsic viscosity 1 g of the polymer was mixed with phenol / tetrachloroethane = 50.
/ 50 (weight ratio) in 100 ml of a mixed solvent.
It was measured at 0.0 ° C.

(4) Thermal Stability About 10 g of a polymer was placed in a glass test tube having a content of 50 ml, dried at 160 ° C. for 2 hours under a high vacuum, and then depressurized to 100 mmHg with nitrogen gas to melt the glass test tube. After sealing,
Heat treatment was performed at 290 ° C. for 2 hours, the intrinsic viscosity before and after the heat treatment was measured, and the intrinsic viscosity retention was determined from the following equation.

[0026]

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

(5) Runnability On a smooth glass plate, two films cut to a width of 15 mm and a length of 150 mm are stacked, and a rubber plate is placed thereon, and the contact pressure of the two films is 2 g / cm ^2. As 20m
Measure the frictional force by sliding the films at m / min,
The coefficient of friction at the point of sliding by 5 mm was determined as the dynamic friction coefficient. The measurement was conducted at a temperature of 23 ° C. ± 1 ° C. and a humidity of 50% ± 5.
% Atmosphere.

(6) Wear Characteristics Wear characteristics were evaluated based on the amount of white powder generated. The film was run over 1000 m while the film was in contact with the hard chrome fixing pin, and the amount of abrasion white powder adhering to the 6 mmφ hard chrome fixing pin was visually evaluated and classified according to the rank shown below. The film speed was 13 m / min, the tension was about 200 g, and the winding angle of the film around the pin was 135.
°. Rank A: Not attached at all Rank B: Attach a small amount Rank C: Attach a small amount (more than Rank B) Rank D: Attach very much

(7) Number of Coarse Protrusions 10 mg of a sample was accurately weighed, sandwiched between 18 × 18 mm cover glasses, and hot-pressed at 280 to 290 ° C. to obtain a diameter of about 1 mm.
A 0 mm film was prepared, and the film was observed with a phase contrast microscope (100 times), and the number of coarse protrusions having a maximum length of 10 μm or more was counted.

(8) Transparency The film haze was measured according to JIS-K61714 using a spectroscopic turbidimeter NDH-20D manufactured by Nippon Denshoku Industries.

Example 1 [Preparation of slurry] 100 parts of water and 0.05 part of a silane coupling agent vinyltriethoxysilane were added to 10 parts of silica particles having an average particle diameter of 0.80 μm and a number of silanol groups of 8.0 / nm ^2. In addition, the mixture was stirred at 60 ° C. for 1 hour to block the silanol groups of the particles (the silanol group blocking rate was 5%).
4.5%). Next, the particles were separated by filtration and dried to obtain a powder.

90 parts of ethylene glycol was added to 10 parts of the particle powder obtained as described above, and the mixture was subjected to 10,000 rpm-6 with a homomixer (TK homomixer manufactured by Tokushu Kika Kogyo Co., Ltd.).
The mixture was dispersed for 0 minute and filtered through a 1000 mesh wire mesh filter 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 were placed in a reactor, heated and heated, and methanol was distilled off to carry out a transesterification reaction, and the reaction was started. After 4 hours, the temperature was raised to 230 ° C. to substantially complete the transesterification reaction. Next, after adding 3 parts of the above slurry, ethyl acid phosphate 0.0
4 parts were added, and further 0.04 parts of antimony trioxide was added to carry out a polycondensation reaction, whereby polyethylene terephthalate having an intrinsic viscosity of 0.660 was obtained in 4 hours and 10 minutes.

After drying the obtained polyester, it was melt-extruded at 290 ° C. to form 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.
Heat treatment for 3 seconds to obtain a film having a thickness of 15 μm,
Its properties were evaluated. As a result, the polymerizability, the thermal stability, etc. were good, and the film properties were also very good.

Example 2 Polycondensation was conducted in the same manner as in Example 1 except that silica particles having an average particle size of 1.25 μm, an initial number of silanol groups of 8.0 / nm ² , and a silanol group blocking rate of 57.0% were used. The reaction was performed, and after 4 hours and 5 minutes, polyethylene terephthalate having an intrinsic viscosity of 0.662 was obtained. Further, a film was obtained in the same manner as in Example 1, and its characteristics were evaluated.

Example 3 Polycondensation was carried out in the same manner as in Example 1 except that silica particles having an average particle size of 1.25 μm, an initial number of silanol groups of 7.0 / nm ² , and a silanol group blocking rate of 65.0% were used. The reaction was performed, and after 4 hours and 2 minutes, polyethylene terephthalate having an intrinsic viscosity of 0.665 was obtained. Further, a film was obtained in the same manner as in Example 1, and its characteristics were evaluated.

Comparative Example 1 A polycondensation reaction was carried out in the same manner as in Example 1 except that silica particles having an average particle diameter of 0.80 μm, an initial number of silanol groups of 7.0 / nm ² , and a silanol group blocking rate of 0% were used. After 5 hours and 30 minutes, polyethylene terephthalate having an intrinsic viscosity of 0.651 was obtained. Further, a film was obtained in the same manner as in Example 1, and its characteristics were evaluated. The polymerizability and thermal stability of polyethylene terephthalate were poor, and the resulting film had many coarse projections and poor transparency.

Comparative Example 2 A polycondensation reaction was carried out in the same manner as in Example 1 except that silica particles having an average particle size of 1.25 μm, an initial number of silanol groups of 8.0 / nm ² , and a silanol group blocking rate of 15% were used. After 5 hours and 5 minutes, polyethylene terephthalate having an intrinsic viscosity of 0.650 was obtained. Further, a film was obtained in the same manner as in Example 1, and its characteristics were evaluated. The polymerizability and thermal stability of polyethylene terephthalate were poor, and the resulting film had many coarse projections and poor transparency.

Comparative Example 3 A polycondensation reaction was carried out in the same manner as in Example 1 except that silica particles having an average particle size of 1.25 μm, an initial number of silanol groups of 8.0 / nm ² , and a silanol group blocking rate of 85% were used. After 4 hours and 5 minutes, polyethylene terephthalate having an intrinsic viscosity of 0.665 was obtained.

Further, a film was obtained in the same manner as in Example 1, and its characteristics were evaluated. Although the polymerizability and thermal stability of polyethylene terephthalate were good, it was difficult to make the particles into an ethylene glycol slurry, and the resulting film had many coarse projections and transparency due to the presence of coarse particles in the slurry. Was also bad. The results obtained above are shown in Table 1 below.

[0041]

[Table 1]

[0042]

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

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-312345 (JP, A) JP-A-63-317533 (JP, A) JP-A-1-144423 (JP, A) JP-A-4- 93348 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) C08J 5/18 C08L 67/02-67/04 C08K 3/36 C08K 9/06

Claims (1)

(57) [Claims] 1. An average particle size obtained from silica particles containing 5 to 30 silanol groups / nm ² , wherein 30 to 70% of all silanol groups are blocked by a silane coupling agent treatment. A polyester film comprising 0.001 to 5% by weight of 0.1 to 5 μm silica particles.