JPH01204959A - Polyester composition and biaxially oriented polyester film prepared therefrom - Google Patents

Abstract

PURPOSE:To provide a polyester composition which can give a molding, such as a film or a fiber, possessing both easy slidability and abrasion resistance, by adding a specified amount of specified silicone rubber particles to a polyester. CONSTITUTION:Silicone rubber particles of a mean particle diameter of 0.01-5mum, having structural units of the formula (wherein R1, R2 and R3 are each methyl, ethyl or phenyl, and m:n=5:95-80:20) are prepared. In the production of a polyester (e.g., polyethylene terephthalate), the prepared particles are added to the reaction system to produce a polyester containing 0.005-15wt.% silicone rubber particles. The obtained polyester composition is melt-molded into a film, and this film is biaxially oriented and heat-set to produce a biaxially oriented polyester film excellent in lubricity and chipping resistance and suitable for, e.g., a magnetic tape.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a polyester composition, and more particularly to a molded article containing silicone rubber fine particles and having excellent slip properties and abrasion resistance, particularly a two-wheel stretched polyester film. The present invention relates to a polyester composition capable of forming a polyester composition.

[Prior Art] Due to its excellent physical and chemical properties, polyester represented by polyethylene terephthalate is used as film for magnetic tapes, photographs, capacitors, packaging, etc., and as textiles for clothing, industrial use, etc. As, also a sheet,
Widely used for molded products such as tubes.

The slipperiness and abrasion resistance of these molded products are major factors that determine the workability of the manufacturing process of the molded product and the processing process in each application, as well as the quality of the product.

In particular, when used as a film for magnetic tape, the friction and wear between the coating roll and the film surface during application of the magnetic layer is extremely severe, which tends to cause process and quality problems. In addition, when used as a magnetic tape product, significant wear occurs between many guide parts, heads, etc., causing scratches and white powdery substances due to scratches on the surface of the polyester film. This is often a major cause of dropouts in recorded signals.

In order to solve these problems, a method is generally adopted in which the surface of the film is made uneven to reduce the contact area between films or between films and guides. For example, titanium oxide, carbonate A method of adding fine particles such as calcium is used. The larger the size difference of the fine particles in these raw material polymers, the greater the effect of improving slipperiness. However, if the size of the particles is increased, the abrasion resistance generally decreases and problems such as falling off occur, so there is currently a demand to satisfy both slipperiness and abrasion resistance at the same time.

For this purpose, JP-A-62-172031 proposes a biaxially oriented polyester film to which organopolysiloxane resin particles are added, but even with this method, the effect of improving abrasion resistance is not necessarily sufficient.

(Problems to be Solved by the Invention) An object of the present invention is to solve the above-mentioned problems and to provide a polyester composition that has excellent slipperiness and abrasion resistance when molded into a molded article, especially a film. be.

[Means for Solving the Problems] - The object of the present invention is to prepare silicone rubber particles whose structural unit has an average particle diameter of 0.01 to 5 μm represented by the following maximum (I) to 0.00 μm.
This can be achieved by a polyester composition characterized by containing 5 to 15% by weight and a biaxially stretched polyester film made from the polyester composition.

(RIS! 03/2 > 1T1 (R2R3S
! O). (I) In the present invention, the 2-polyester is a polyester containing an aromatic dicarboxylic acid as a main glycol component and an aliphatic glycol as a main dicarboxylic acid component. Such polyesters are substantially linear and have film forming properties, particularly by melt molding. Examples of aromatic dicarboxylic acids include terephthalic acid, naphthalene dicarboxylic acid, isophthalic acid, dipheninoxyethane dicarboxylic acid, bis(chlorophenoxy)ethane dicarboxylic acid, diphenyl dicarboxylic acid, diphenylsulfone dicarboxylic acid, diphenylketone dicarboxylic acid, and anthracene dicarboxylic acid. Examples of aliphatic glycols include polyethylene glycols having 2 to 10 carbon atoms such as trimethylene glycol, tetramethylene glycol, pentamethylene glycol, hexamethylene glycol, and decamethylene glycol, or cyclohexane dimetatool. Examples include alicyclic diols such as the following.' In the present invention, polyesters containing, for example, alkylene terephthalate and/or alkylene naphthalate as main constituents are preferably used.

Specific polyesters include, for example, polyethylene terephthalate, polyethylene-1,2-bis(2-chlorophenoxy)ethane-4,4'-dicarboxylate, and polyethylene-2.

In addition to 6-naphthalate, for example, 80 mol% or more of the total dicarboxylic acid component is terephthalic acid and/or 2-naphthalate.
, 6-naphthalene dicarboxylic acid, and a copolymer in which 80 moles or more of the glycol component is ethylene glycol is preferred.

In this case, 20 mol% or less of the dicarboxylic acid in the acid component can be the above-mentioned aromatic dicarboxylic acid, and for example, aliphatic dicarboxylic acids such as adipic acid and sebacic acid, dichlorohexane-1,4-dicarboxylic acid, etc. Alicyclic dicarboxylic acids and the like can be used. In addition, up to 20 mol% of the glycol component can be ``the above-mentioned glycols other than ethylene glycol, or aromatic diols such as hydroquinone, resorcinol, 2,2-bis(4-hydroxyphenyl)propane, etc. 1,4
- Aromatic-containing aliphatic diols such as dihydroxymethylbenzene; alkylene glycols (polyoxyalkylene glycols) such as polyethylene glycol and polytetramethylene glycol; and the like.

Furthermore, in the polyester used in the present invention, a component derived from an oxycarboxylic acid such as an aromatic oxyM such as hydroxybenzoic acid and an aliphatic oxycarboxylic acid such as ω-hydroxycaproic acid, a dicarboxylic acid component, and an oxycarboxylic acid component. It also includes those copolymerized or bonded in an amount of 20 mol % or less based on the total amount of components.

Furthermore, the polyester in the present invention contains a trifunctional or higher functional polycarboxylic acid or a polybitroxy compound, such as trimellitic acid, pentaerythritol, in an amount within a substantially linear range, for example, an amount of 2 mol % or less based on the total acid components. Copolymers of these are also included. The above-mentioned polyester is known per se, and can be produced by a method known per se.

The above polyester has an intrinsic viscosity of about 0.4 measured as a solution in 0-chlorophenol at 35°C.
~0.9 is preferred.

The biaxially stretched polyester film of the present invention has many fine protrusions on its surface. According to the present invention, these many fine protrusions are derived from a large number of silicone rubber fine particles dispersed and contained in the polyester.

Polyester containing dispersed silicone rubber particles is
Usually, silicone rubber fine particles (preferably as a glycol slurry) are added during the reaction to form a polyester, for example, before or during the transesterification reaction when using a transesterification method, or at any time during the reaction when using a direct polymerization method. It can be produced by adding into the reaction system. Preferably, silicone rubber fine particles are added to the reaction system at the beginning of the polycondensation reaction, for example, until the intrinsic viscosity reaches about 0.3. At that time, powder may be added to the reaction system, but preferably,
It is preferable to add it to the reaction system as a glycol slurry constituting the polyester.

Further, when adding the glycol slurry to the reaction system, it is more preferable to disperse the glycol slurry by ultrasonication or ordinary stirring and dispersion treatment, and then add the glycol slurry.

In the present invention, the silicone rubber particles contained in the polyester have a composition of RIS! Trifunctional organopolysiloxane represented by 0372 (R1 is methyl, ethyl, phenyl group) and R2R3S fO (R2R
3 is a methyl, ethyl, or phenyl group, which may be the same or different), and has an average particle diameter of 0.01 to 5 μm.
Silishene rubber particles.

RSiO3/2 in the above structural unit composition is an organopolysiloxane with a three-dimensional bonding structure represented by the following structural formula % Formula %, and the composition ratio with the bifunctional organopolysiloxane represented by R2R35iO is 5:95 ~ 80:2
0, preferably 10:90 to 75:25. More preferably, the ratio is 15:85 to 70:30. When the proportion of trifunctional organopolysiloxane exceeds 80 mol%, the hardness of the particles increases, and when formed into a film or fiber, voids are likely to be formed around the particles, resulting in insufficient heat resistance. .

That is, if it is less than 80 mol%, it will undergo elastic deformation during molding and a void-free molded product will be obtained.

On the other hand, if the constituent proportion is less than 5 mol%, the abrasion resistance is poor and it is undesirable because it decomposes during the production of polyester or during the molding of films and fibers, causing film tearing and thread breakage.

Further, the degree of polymerization of the silicone rubber particles is preferably 100 or more.

The silicone rubber particles have excellent lubricity, have a lower specific gravity than inert inorganic particles, and have better heat resistance than organic fine particles, and are insoluble in organic solvents, It also has the characteristic of being non-melting. Furthermore, silicone rubber particles exhibit excellent affinity for polyester.

The silicone rubber particles used in the present invention have an average particle size of 0.
0.01 to 5 μm, preferably 0.005 to 3 μm, and more preferably 0.1 to 2 μm. The average particle diameter is 0.
If it is less than 0.1 μm, the effect of improving slipperiness and abrasion resistance is insufficient, and if it exceeds 5 μm, the surface flatness is insufficient, which is not preferable.゛The average particle diameter referred to herein is expressed as the diameter at the cumulative 50% point of the equivalent spherical diameter particle size distribution calculated based on Stokes' equation.

In order to obtain particles with a predetermined average particle size, pulverization treatment or classification operation of commercially available silicone rubber fine particles may be employed.

Further, the silicone rubber particles were heated to 300 ml under a nitrogen atmosphere.
It is preferable that the weight loss rate at °C is 5% or less. Generally, amine-based alkali compounds are used in the synthesis process for such silicone compounds, but if these impurities remain on the surface of the final silicone rubber particles, the weight loss rate at 300'C increases, which is undesirable.

If the weight loss rate exceeds 5% at 300°C in a nitrogen atmosphere, decomposition will occur during the polyester manufacturing process and film/fiber molding process, resulting in polyester coloring, polymerization retardation, and
Moreover, this is not preferable as it may cause film tearing or thread breakage.

In the present invention, the amount of silicone rubber particles added must be 0.005 to 15% by weight based on the polyester, preferably 0.01 to 5% by weight.
．． If it is less than 0.005% by weight, the slipperiness will be insufficient;
If it exceeds 5% by weight, the surface flatness decreases and the electromagnetic conversion characteristics when formed into a film and used in a magnetic tape are deteriorated, which is not preferable.

The silicone rubber particles are not limited in any way in terms of their manufacturing method, as long as they satisfy the above conditions.

When the polyester composition of the present invention is used to form a film, for example, it can be produced in accordance with conventionally accumulated methods for producing two-wheel stretched films.

For example, it is manufactured by melt-casting a polyester containing silicone rubber fine particles to form an amorphous unstretched film, then stretching the unstretched film in the direction of the two wheels, heat setting, and if necessary, subjecting it to relaxation heat treatment. be done. At this time, the surface characteristics of the film vary depending on the shape, particle size, etc. of the silicone rubber particles, and also depending on the stretching conditions, so they are appropriately selected from conventional stretching conditions. In addition, since voids, density, thermal shrinkage rate, etc. change depending on the temperature, magnification, speed, etc. during stretching and heat treatment, conditions are determined to satisfy these characteristics at the same time. For example, the stretching temperature ranges from (Tq-10) to (Tg+45
) °C (however, Tg: the glass transition temperature of polyester), and the second-stage stretching temperature (for example, lateral stretching temperature, 2nd) is preferably selected from the range of (Ti-15) to (T1+40>'C). .

Further, the stretching ratio is preferably selected from a range in which the uniaxial stretching ratio is 2.5 or more, particularly 3 times or more, and the area magnification is 8 times or more, especially 10 times or more.

Furthermore, the heat setting temperature is 180 to 250'C, and even 2
It is preferable to select from the range of 00 to 230°C. As a result, 1q of biaxially oriented polyester films with excellent slip properties and excellent abrasion resistance can be obtained.

This biaxially oriented polyester film is preferably used as a base film for magnetic recording media, especially as a base film for magnetic tapes, but is not limited to this, but is also used in other fields such as electrical applications, packaging applications, and deposition films. It can also be widely applied to

In addition to this kind of film, even when formed into fibers, it is possible to create threads with excellent surface properties.

[Example] The present invention will be further explained below with reference to Examples.

Note that various physical property values and characteristics in the present invention were measured and defined as follows.

(1) Average particle diameter A slurry containing silicone rubber particles was measured using a conventional liquid phase sedimentation method and expressed as the "equivalent spherical diameter" of the particles at a point of 50% by weight of the total particles. The term "equivalent spherical diameter" as used herein means the diameter of an imaginary sphere having the same volume as the silicone rubber particle.

<2> Weight loss rate at 300°C After drying the raw powder of silicone rubber particles at 100°C for 2 hours, the temperature was raised at 10°C/min in a nitrogen atmosphere using a thermobalance to reach 300°C. The amount of weight loss was measured.

(3) Roughness of film surface irregularities The film surface was observed using a microscopic light wave interferometer, and the difference between the highest and lowest parts of the obtained surface irregularities was expressed in μ units.

(4) Coefficient of Friction of Film The tension on both sides of the metal guide was measured while the film was running, and the coefficient of dynamic friction was determined.

(5) Wear-resistant film is slit into thin strips, then passed through a winder, rubbed against a metal guide rail installed in the middle, and run at high speed. The amount of white powder generated is measured, and then ranked. 21 or more was considered to be a pass.

Grade 1: No white powder is generated.

Grade 2: A slight amount of white powder is generated.

Grade 3: A considerable amount of white powder is generated.

Grade 4: Large amount of white powder.

Example 1 Silicone rubber particles ([(CH3S ! 03/2) 7((CH
3) 23! 90 parts by weight of ethylene glycol was added to 10 parts by weight of O)3In), treated with ultrasonic waves for 30 minutes, and then filtered through a 10μ filter until the average diameter of the primary particles was 1.
A slurry of 0μ was obtained.

Next, 8100 parts by weight of dimethyl terephtasy, 65 parts by weight of ethylene glycol, and 0.08 parts by weight of magnesium acetate were charged, and after transesterification was carried out in the usual manner, 0.04 parts by weight of trimethyl phosphate and 0.04 parts by weight of trioxide were added. After adding 0.05 parts by weight of antimony and roughly adding 1 part by weight of the above-mentioned slurry, a normal polycondensation reaction was carried out,
A polyester composition having an intrinsic viscosity of 0.625 and a softening point of 260°C was obtained.

Next, using the obtained polyester composition, the stretching ratio lengthwise was 3.
．． A two-wheeled stretched film with a thickness of 10 μm was formed under conditions of 3 times the width, 3.5 times the width, a heat treatment temperature of 215° C., and a heat treatment time of 5 seconds. As shown in Table 1, the obtained film had a roughness of 0.018μ and a coefficient of dynamic friction of 0.24.
It was found that the abrasion resistance of the film was first grade, and that it had both slipperiness and abrasion resistance that were sufficiently satisfactory for use in magnetic tapes.

Examples 2 to 5 The same procedure as in Example 1 was carried out by changing the average particle diameter of the primary particles, the weight loss rate at 300'C, the ratio of trifunctional organopolysiloxane/bifunctional organopolysiloxane, and the addition port of silicone rubber particles. According to the method, 1 q of polyester composition as well as biaxially oriented film was prepared.

Table 1 shows the surface roughness, dynamic friction coefficient, and abrasion resistance of the obtained film. As can be seen from this table, the obtained biaxially stretched film has sufficient slipperiness and abrasion resistance for magnetic tape applications.

Comparative Examples 1 to 4 Examples 1 to 4 were prepared by changing the average particle diameter of the primary particles, the weight loss rate at 300°C, the ratio of trifunctional organopolysiloxane/bifunctional organopolysiloxane, and the amount of silicone rubber particles added. 1 q of a polyester composition and a biaxially stretched film were prepared in the same manner.

Table 1 shows the surface roughness, dynamic friction coefficient, and abrasion resistance of the obtained film. As can be seen from this table, the 1q biaxially stretched film has excellent slipperiness, but it has poor abrasion resistance and frequently breaks during film formation, so it is not suitable for magnetic tape applications. did not have sufficient performance.

(The following is a blank space) [Effects of the Invention] The polyester composition 1q of the present invention contains a specific amount of special silicone rubber particles in the polyester, so when it is made into a molded product, it has good slipperiness and abrasion resistance. It is possible to make molded products with excellent properties that combine both strength and strength.

Therefore, the composition of the present invention is effective in the field of fibers, films, and other engineering plastics, and can be particularly preferably used in the film field, such as magnetic tape applications.

Claims (2)

[Claims] (1) Silicone rubber particles whose structural units are represented by the following general formula (I) and have an average particle diameter of 0.01 to 5 μm are prepared at 0.00.
A polyester composition characterized by containing 0.005 to 15% by weight. (R_1SiO_3_/_2)_m (R_2R_3SiO)_n(I) However, R_1, R_2, and R_3 represent methyl, ethyl, or phenyl groups, and may be the same or different. Also, m:n=5:95 to 80:20. (2) A biaxially stretched polyester film comprising the polyester composition according to claim (1).