JPH01176556A - Composite polyester film - Google Patents

Abstract

PURPOSE:To satisfy antipodal characteristics of a polyester film, namely, transparency and surface smoothness and, operability, by compounding a polyester resin layer containing a specified silica on one surface of a polyester resin layer not containing a smoothing agent. CONSTITUTION:A layer B composed of polyester resin containing silica by the amount satisfying an equation II is compounded at least on one surface of a layer A composed of polyester resin substantially not containing a smoothing agent. The above silica is 5-500mmu in the average diameter of a particle thereof obtained through observation of a scanning-type electronic microscope, with the area percentage of not less than 80% with respect to a circumscribed circle defined by an equation I. In the equation II, references D and C respectively denote the average diameter of a particle of the silica represented by mmu, and the containing amount of the silica in the polyester represented by weight%. The thickness ratio of the layer B is preferably 0.01-0.2 with respect to the layer A.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an oriented polyester film that has good transparency, easy slippage, and smooth surface, has a small number of coarse particles, and has good film workability.

(Prior art) Polyester, represented by polyethylene terephthalate, is generally used for textiles, molded products, magnetic tapes, photographs, capacitors, packaging, etc. due to its excellent physical and chemical properties. It is widely used in a variety of applications, including as film. When these films are used, their transparency, slipperiness, and abrasion resistance are major factors that determine the workability of the film manufacturing process and processing process in each application, as well as the quality of the product. There is.

For example, when used in the packaging, optical, and printing fields, a film with high transparency and excellent slipperiness is desired.

In addition, regarding the use of magnetic recording media, demands for higher recording density, higher quality, longer recording time, and compactness have become stricter in recent years. Among them, metal coating type and vapor deposition type 8
(2) Magnetic tapes that require a high S/N ratio, such as those used for video tapes and digital audio tapes, have thin magnetic layers, so the surface morphology of the base film used is directly transferred to the magnetic layer. Therefore, if the surface roughness of the base film is rough, the electromagnetic conversion characteristics of the video tape after coating or vapor deposition of the metal magnetic material will be significantly deteriorated. Furthermore, even fine protrusions that do not affect the electromagnetic transducer properties of a video tape in a general-purpose grade video base film cause deterioration of the electromagnetic transducer properties in the above-mentioned magnetic tape applications. In terms of electromagnetic conversion characteristics, it is preferable to use a base film with a perfectly smooth mirror surface free of inert inorganic particles and insoluble particles due to catalyst residue, but the magnetic layer formed on such a base film is Since the surface remains mirror-like, workability is very poor. −Generally, to improve the workability of films,
A method has been adopted to reduce the contact area between the film surface and guide rolls, etc. by adding unevenness to the surface of the film. (Japanese Patent Publication No. 49-13234 and Japanese Patent Publication No. 5O-E3493, etc.), or (1) Adding one or more types of inert inorganic particles -L at an appropriate time during the polyester manufacturing process. A large number of proposals have been made including methods (Japanese Patent Publication No. 55-40929 and USP 3°980.611, etc.).

However, in these conventional techniques, the larger the particle size of the particles in the raw material polymer, the better the sliding property improvement effect is. For magnetic tape applications where surface smoothness is strongly required, such as video tape applications, the large size of the particles itself causes defects such as dropouts, and furthermore, the electromagnetic conversion characteristics are also significantly deteriorated. For this reason, there is currently a demand to simultaneously satisfy the contradictory characteristics of making the irregularities on the film surface as fine as possible and not impairing workability.

(Problems to be Solved by the Invention) In view of the actual situation as described in 1-1, the present invention provides an orientation that satisfies the contradictory properties of excellent transparency, surface smoothness, and workability. The purpose is to provide a polyester film.

(Means for Solving the Problems) The present invention provides that at least one side of layer A, which is made of a polyester resin that does not substantially contain a lubricant, has an average particle diameter of 5 mμ to 500 mμ, as observed with a scanning electron microscope. , and the area ratio with respect to the circumscribed circle defined by equation (1) is 80
% or more of silica in an amount satisfying the following formula 0.

10≦+Di X (C1≦300 −−−−−−−
−−−−−−−−−−−−−−−−−−−■The polyester used in the present invention is a crystalline polyester with polyethylene terephthalate, polyalkylene naphthalate, etc., and is not particularly limited. Particularly suitable is polyethylene terephthalate, in which 80 mol% or more of its repeating units consist of ethylene terephthalate, and other copolymer components include isophthalic acid, p-β-oxyethoxybenzoic acid, 2,6-naphthalene. Dicarboxylic acid, 4.4'-dicarboxyldiphenyl, 4.4'-dicarboxylbenzophenone, bis-(4-carboxylphenyl)ethane, adipic acid, sebacic acid, 5-sodium sulfoisophthalic acid,
Dicarboxylic acid components such as cyclohexane-1,4-dicarboxylic acid, propylene glycol, butanediol, neopentyl glycol, diethylene glycol, cyclohexanedimethanol, ethylene oxide adducts of bisphenol A, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, etc. Glycol components, oxycarboxylic acid components such as p-oxybenzoic acid, etc. can be arbitrarily selected and used. In addition, compounds containing small amounts of amide bonds, urethane bonds, ether bonds, carbonate bonds, etc. as copolymerization components. May contain.

The method for producing the polyester includes a so-called direct polymerization method in which aromatic dicarboxylic acid and glycol are directly reacted;
Any production method can be applied, such as the so-called transesterification method in which dimethyl ester of aromatic dicarboxylic acid and glycol are transesterified.

Here, the polyester resin of layer A is the above-mentioned polyester resin that does not substantially contain a lubricant, and for example, a polyester resin prepared by the method disclosed in JP-A-59-6262.7 is used. is preferred. - For the polyester resin of the 8 layers, it is necessary to use a polyester resin containing a certain amount of silica.

Regarding the thickness relationship between layer A and layer B, it is preferable that the thickness of layer B with respect to layer A is 0.01 to 0.2. 0
．． If it exceeds 2, the steepness of the surface protrusions formed by the silica particles will become lower and slipperiness will deteriorate, which is not preferable.

There is also the problem that transparency becomes low. On the contrary, 0.01
It is not preferable to have no grooves because it becomes difficult to control the thickness.

The silica used in the present invention preferably has an average particle diameter of 5rnμ or more - L500 plastic when observed with a scanning electron microscope, and has a particle size of 5 molar or more and 100 mp or less. 1
Particularly preferred are those having a value of 0rnμ to 780+++μ.

If the average particle size is 5 mp without grooves, the effect of improving slipperiness will be insufficient, so this is not preferable. On the other hand, if it exceeds 500 mμ, the surface smoothness and transparency will deteriorate, which is not preferable.

Further, the shape of the silica particles is also important, and a film with excellent slipperiness and abrasion resistance can be obtained by using particles as close to a true sphere as possible. In order to achieve the object of the present invention, it is preferable that the area ratio with respect to the circumscribed circle expressed by the following formula obtained by observation with a scanning electron microscope is 80% or more. 90%
The above is particularly preferable.

Furthermore, it is preferable that the particle size distribution of the silica be as sharp as possible. If the particle size distribution of the particles is extremely sharp and close to medium dispersion, the height and shape of the protrusions formed on the film surface will be nearly uniform, which meets the purpose of the present invention. To achieve this purpose, the degree of dispersion of particle diameters observed with a scanning electron microscope must be 25%.
% or less, more preferably 20% or less.

The silica content varies depending on the average particle diameter of the silica, and is the product of the average particle diameter fD+ shown in A and the silica content fcl expressed in weight% relative to the polyester CfDI X (C)
] is preferably in the range of 10 to 300. 20-200
The range is more preferable. If fDI x fc) is less than 10, even if the average particle diameter satisfies the above range, the slipperiness deteriorates, which is not preferable. On the other hand, if (Di×(C)) exceeds 300, the surface smoothness deteriorates even if the average particle diameter satisfies the above range, and for example, metal coating type 8
It is not preferable for use in magnetic tapes such as Ryu Videotape, which require strong surface smoothness, because the electromagnetic conversion properties will be insufficient. Furthermore, the transparency is also low, making it difficult to use in fields such as graphic arts, which require a high degree of transparency, which is not preferable.

In addition, the silica content is 1.0 while satisfying the above conditions.
It is preferably in a range of 20% by weight or more by weight.

By setting the amount within this range, the effects of the present invention can be more clearly exhibited.

The silica is preferably colloidal silica, but is not particularly limited. For example, spherical silica generally referred to as white carbon synthesized by a dry method or wet method, or secondary agglomerated amorphous silica subjected to a dispersion treatment to be dispersed down to primary particles may be used.

One type of silica may be used, or two or more types may be used in combination. In addition, if it is a small amount, 7 Lika, which is outside the scope of this patent, may be used in combination. Furthermore, inert particles other than silica or so-called internal particles generated in the polyester manufacturing process may be used in combination.

The warping force may be one without surface treatment or one with surface treatment. Furthermore, there are no particular limitations on whether or not an agglomeration inhibitor or dispersion aid is used.

In the method of adding silica to polyester in the present invention, silica can be added at any stage in the polyester manufacturing process, but it is particularly preferable to add silica before the initial condensation is completed. In addition, inert particles can be added to the polyester manufacturing process in either slurry or powder form, but from the viewpoint of preventing particle scattering and improving feeding accuracy and uniformity, it is preferable to add inert particles in slurry form. It is preferable to add it in a dispersed form, and it is particularly preferable to add it in a slurry of ethylene glycol (EG). When dispersing in slurry form, it is necessary to perform uniform dispersion to reproduce the original primary particles of each particle as much as possible. Furthermore, commercially available fine particles may be subjected to treatments such as pulverization, classification, and filtration in order to obtain particles with a predetermined average particle size.

Alternatively, a polyester containing a high concentration of individual particles within a range that does not agglomerate may be separately produced in advance, and then blended to a predetermined particle moisture content.

The structure of the A layer and the B layer in the present invention is such that B layer is on one side of the A layer.
Either a composite layer or a composite layer B on both sides of layer A may be used. In the case of a double-sided composite, the thickness of the B layer may be the same or different.

The composite film of the present invention can be manufactured by conventional methods for manufacturing composite films.

For example, the polyester layer forming layer A and the polyester layer forming layer B can be combined in a molten state or in a cooled and solidified state. Specifically, it can be manufactured by methods such as coextrusion and extrusion coating. Among these manufacturing methods, a coextrusion method in which composite materials are combined in a molten state is particularly preferred.

The oriented polyester film of the present invention must be stretched 1.1 times or more in at least one direction. 3
It is preferable that the paper be stretched to double the amount. Triaxially oriented films are particularly suitable. The stretching process is carried out by an inflation method, a tenter method, a roll method, or a combination thereof.

For example, in the case of polyethylene terephthalate, the temperature at which the stretching is performed is generally from 80°C to 100°C; It is preferable to carry out C. 110°C to 130'C is more preferred.

(Example) Next, Examples and Comparative Examples of the present invention will be shown. All parts in the examples mean parts by weight unless otherwise specified.

In addition, the measurement method used is shown below.

(1) Average particle size: Inert particles were examined using a scanning electron microscope (S-510 model).
The observed and photographed particles were enlarged and copied, and further traced and 200 particles were randomly painted black. Using this image as an image analysis device (Luxex Model 500, manufactured by Reco Co., Ltd.), the horizontal Feer diameter was measured, and the average value was taken as the average particle diameter. Further, the degree of variation in particle diameter was calculated using the following formula.

■ Randomly select 20 particles from the trace image used to measure the area ratio average particle diameter with respect to the circumscribed circle, and calculate the projected cross-sectional area of each particle by (
It was measured using the image analysis device used in 1).

Further, by calculating the area of a circle circumscribing those particles, the area ratio was determined using the following formula.

(3) Film base Measured with a direct reading base meter (manufactured by Toyo Seiki Co., Ltd.).

(4) Surface smoothness of the film Surfcom 300A type surface roughness, using IL (manufactured by Tokyo Seimitsu), side diameter 1 μm, weight 0.07 g 1 measurement standard length 0.8
11111 Displayed as average roughness (Ra (μm)) from the center line to 1 measured under the conditions of cutoff o and osmm.

(5) Coefficient of Dynamic Friction In accordance with ASTM D-1894-63, the coefficient of friction between films is determined using a slend type slip tester under environmental conditions of 23°C and 65RH%.

(6) Film workability: When slitting the film and winding it into a roll, evaluate on a four-point scale whether or not you can obtain problem-free pickpockets and trawls without causing poor winding, wrinkles, air bubbles, etc. It is expressed with the following ranking.

X---------It is always difficult to obtain a problem-free slit roll △------------It is possible to obtain a problem-free slit roll at low speed0------- --It is possible to obtain a problem-free slit roll at high speed. ◎-----It is easy to obtain a problem-free slit roll at high speed. (7) Number of coarse protrusions on the film surface. Aluminum on the film surface. After a thin layer is deposited, the number of coarse protrusions (number per measurement area) of quadruple rings is counted using a two-beam interference microscope, and the number of coarse protrusions is ranked according to the number of coarse protrusions as follows.

1st grade-----I E3 or more/-2nd grade----
-----12~15 pieces/-3rd grade---8~1
1 piece/wii 4th grade-----4 to 7 pieces/-5th grade----0 to 3 pieces/1 Example 1 1) Production of polyester A Thick stirring device, min. Using a continuous esterification reactor consisting of a two-stage complete mixing tank equipped with a condenser, a raw material inlet, and a product outlet, terephthalate is added to the system in which the esterification reaction components of the first esterification reactor are present. Adjust the molar ratio of ethylene glycol (EG) to acid (TPA) to 1.7,
And antimony trioxide as an antimony atom is 289 ppm per TPA unit, and magnesium acetate tetrahydrate as an Mg atom is 100 ppm based on the polyester produced.
A TPA0′)EG slurry containing an amount of m was continuously fed. Average residence time 4.5 hours at normal pressure, temperature 25
The reaction was carried out at 5°C.

This reaction product was continuously taken out of the system and supplied to the second esterification reactor. Furthermore, EG was continuously added in an amount of 0.5 parts by weight per polyester unit, and the mixture was reacted at normal pressure for an average residence time of 5.0 hours at a temperature of 260°C. The esterification rate of the final reaction product was 98%.

1,144 parts of the esterification reaction product (equivalent to 1,100 parts of ethylene terephthalate) and 70 parts of EG were added to the polycondensation reaction C1i, heated and stirred at 260°C and normal pressure for 90 minutes, and 130 g/g/g was added at the same temperature and pressure. 2.45 parts by volume of EG solution of trimethyl phosphate of Q (64 ppm as PIQ element, Mg based on the polyester produced)
/I)=2.0) was added, and the mixture was heated and stirred for 10 minutes. Next, 0.78 parts by volume of an EG solution of sodium acetate with a concentration of 50 g/ρ (10 ppm as Na atoms based on the produced polyester) was added at the same temperature and pressure, and the mixture was heated and stirred for 10 minutes at the same temperature and pressure. . While raising the reaction temperature to 290°C over about 100 minutes, the pressure of the reaction system was gradually lowered to 0.5 degrees Hg, and then the temperature was increased to 290°C, 0.5+
Polycondensation reaction was carried out at nmHg for about 100 minutes to obtain a polymer having a solid viscosity of 0.620.

2) Manufacturing method of polyester B 519 parts of terephthalic acid, 431 parts of ethylene glycol,
Triethylamine 0.16 parts, antimony trioxide 0.2
75 parts and 40 g of EG slurry containing 20% by weight of silica, 3 parts (320 ppm in terms of antimony atoms based on the produced polyester), average particle size of 50 plastic, area ratio to circumscribed circle of 96%, and particle size dispersion of 10%. 0.26 parts of an aqueous solution of sodium hydroxide of /Q was placed in a stainless steel autoclave equipped with a stirrer, a distillation column, and a pressure regulator, and after purging with nitrogen, the pressure was increased to maintain a gauge pressure of 2.5 kg/-, and the temperature was maintained at 240°C. The esterification reaction was carried out while continuously removing the water produced at the top of the distillation column. 12 after the start of the reaction
After 0 minutes, the pressure was released, and a product with an esterification rate of 97% was obtained. The esterified product was transferred to a polycondensation reactor at 240°C, and the temperature was raised to 275°C over 30 minutes while the pressure of the reaction system was gradually lowered to 0. The pressure was adjusted to 5 mmHg, and the polycondensation reaction was further carried out at the same temperature and pressure for about 80 minutes. The intrinsic viscosity of the obtained polymer was 0.625.

3) Manufacturing method for composite film A two-layer coextrusion film-forming machine with different esterification rates is made of polyester A as a center layer, and each polyester resin is applied so that 8 layers of polyester are composited on both sides of the center layer A layer. 2
A 12 μm film was obtained by heat treatment at 20°C. Furthermore, A
The extrusion die was adjusted so that the thickness ratio between the layer and both B layers was 1:10:1. The characteristic values of the obtained film are
Shown in the table. The film obtained in this example has excellent transparency, surface smoothness, and slipperiness, has a small number of coarse protrusions, and has good film workability and is of extremely high quality.

Comparative Example 1 Table 1 shows the properties of a film obtained in the same manner as in Example 1 except that polyester B was used for all three layers. The film obtained in this comparative example is inferior to the film obtained in Example 1 in transparency and slipperiness.

Comparative Example 2 Table 1 shows the properties of a film obtained in the same manner as in Example 1 except that polyester A was used for all three layers. The film obtained in this comparative example has poor slip properties and film workability, and is of low quality.

Comparative Examples 3-4 Table 1 shows the properties of films obtained by the same method as in Example 1 except that the silica content of polyester B was changed to 0.1% by weight and 8% by weight, respectively. show.

The film obtained in Comparative Example 3 was inferior in slipperiness and film workability, and the film obtained in Comparative Example 4 was inferior in transparency, surface smoothness, and number of coarse protrusions, and was of low quality.

Examples 2 to 4 Table 1 shows the characteristic values of films obtained in the same manner as in Example 1 using the silica shown in Table 1.

All of the films obtained in these Examples had excellent transparency, surface smoothness and slipperiness, had a small number of coarse protrusions, had good film workability, and were of extremely high quality.

Comparative Examples 5 and 6 Table 1 shows the characteristic values of films obtained in the same manner as in Example 1 using silica having an average particle size of 300++μ.

The film obtained in Comparative Example 5 is inferior in transparency, surface smoothness, and number of coarse protrusions, and the film obtained in Comparative Example 6 is inferior in slipperiness and film workability, and is of low quality.

Margins below (Effects of the Invention) The oriented polyester filter obtained by the present invention has excellent transparency, easy slipping properties, and surface 5P slipping properties, has a small number of coarse protrusions, and has good film workability. Suitable for packaging, optical, and printing applications, which require films with high transparency and good slipperiness. Also, the surface has excellent slipperiness, has a small number of coarse particles, and has good slipperiness and film workability. It can be suitably used in the field of magnetic recording media that requires high quality.

Claims (2)

[Claims] (1) At least one side of Layer A made of polyester resin that does not substantially contain a lubricant has an average particle diameter of 5 mμ to 500 mμ as observed with a scanning electron microscope, and is defined by the following formula (1). The area ratio to the circumscribed circle is 80%
A composite polyester film comprising a B layer made of a polyester resin containing silica in an amount satisfying the following formula (2). Area ratio of the projected cross-sectional area of the particle to the circumscribed circle = Projected cross-sectional area of the particle/Area of the circle circumscribing the particle x 100 (1) 10≦(D)
×(C)≦300・・・・・・・・・・・・・・・(
2) [(D) represents the average particle diameter in mμ, (C) represents the silica content in weight % based on the polyester. ] (2) The composite polyester film according to claim 1, wherein the thickness of layer B relative to layer A is 0.01 to 0.2.