JPH0559147B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a polyester composition that can be formed into a film at high speed and has easy slipperiness. More specifically, the present invention relates to a method for producing a polyester composition that can be cast at high speed and has surface properties suitable for the base of magnetic tapes and capacitors. Conventionally, compositions in which so-called internal particles, external particles, or a mixture thereof are contained in polyester have been known as compositions that impart excellent slipperiness and surface roughness. On the other hand, in order to increase the casting speed, as already proposed by the present inventors in JP-A-51-70269,
Another method has been used to lower the resistivity of polyester by adding a metal compound having electrical conductivity to polyester. However, with the combination of such conventional technologies, it has been difficult to have the surface characteristics (particularly slipperiness and surface roughness) required for magnetic tapes and capacitor pastes, and to significantly improve casting speed. . That is, if an attempt is made to lower the resistivity of polyester by adding a conductive metal compound in the polyester manufacturing process, the generation of inert fine particles is suppressed and slipperiness cannot be obtained. On the other hand, even if polyester contains a large amount of inert inorganic particles in order to obtain slipperiness, these inert inorganic particles have little effect on lowering the specific melting resistance of polyester and cannot improve the casting speed. . Furthermore, during the polyester manufacturing process, when a large amount of inorganic particles are added to the polyester, which has a low resistivity, to make it slippery, even the metal compounds that are solubilized in the polymer and have the effect of lowering the specific melt resistance become inactive. Although the reason is not clear, perhaps because they precipitate in the form of fine particles, the specific melting resistance increases and casting speed cannot be improved. An object of the present invention is to overcome these conventional drawbacks and provide a method for producing a polyester composition that can be cast at high speed and exhibits excellent film surface properties. In order to achieve the above object, the present invention has the following configuration:
That is, polyester (A) containing an inert inorganic compound with an average particle size of 0.1 to 5μ (excluding cases where lithium and phosphorus elements are simultaneously included as internal precipitated particles) and a solution haze of 10% or less,
A method for producing a polyester composition by mixing a polyester (B) containing at least one of Mg, Ca, Mn, Co or a compound of these metals and at least one phosphorus compound, the method comprising:
A method for producing a polyester composition, characterized in that the mixing ratio of the polyester (B) in the polyester composition is 3 to 20% by weight. The polyester resin of the present invention refers to a dibasic acid and a dibasic acid.
Refers to a polyester or a copolymer thereof that has film-forming ability and is obtained from a polyhydric alcohol. A typical example of such polyester is polyethylene terephthalate. Of course the third
As a component, it may be a polyester copolymerized with a dibasic acid such as isophthalic acid or adipic acid or a dihydric alcohol such as triethylene glycol or bisphenol A. Furthermore, it may be a mixture of two or more of these polyester resins or copolymers thereof. The inert inorganic compound contained in the polyester (A) of the present invention may be any compound as long as it is inert to the polyester. Examples include calcium acetate, calcium carbonate, calcium phosphate, calcium terephthalate, silicon oxide, aluminum oxide, titanium oxide, magnesium oxide, lithium fluoride, calcium sulfate, barium sulfate, etc., and these may be used alone or in combination of two or more. These inert inorganic compounds may be inert inorganic particles generated in the system during the polyester manufacturing process, so-called internal particles (unless they contain lithium and phosphorus elements at the same time), or ethylene Inorganic particles may be added as a glycol slurry or the like, so-called external particles. Furthermore, internal particles and external particles may be used together. The average particle size of these inorganic particles is 0.1~
5μ, preferably 1 to 3μ. If it is less than 0.1μ, surface protrusions sufficient to provide sufficient slipperiness when made into a biaxially stretched film will not be formed. If the average particle size exceeds 5μ, there is a high possibility that coarse particles of 10μ or more will be included, which is undesirable because it will cause dropouts and a drop in dielectric breakdown voltage when used as a magnetic tape or capacitor base. These inert inorganic particles must be contained in an amount such that the solution haze of the polyester composition finally obtained by the method of the present invention is 20 to 70%, preferably 20 to 50%. If the solution haze is less than 20%, the number of protrusions formed on the surface of the biaxially stretched film will be insufficient, and sufficient slipperiness will not be obtained. On the other hand, if it is 70% or more, the amount of inert inorganic particles is too large, which causes agglomeration between particles, and the surface becomes rough when formed into a biaxially stretched film, which is not preferable. Specifically, the solution haze in these ranges is 0.02% inert inorganic compound in the polyester.
It can be obtained by containing up to 2.0% by weight, preferably 0.025 to 1.0% by weight. The metal or metal compound contained in the polyester (B) of the present invention refers to a metal containing Mg, Ca, Mn, Co, or at least one compound of these metals in a solubilized state in the polyester (B). It is. As examples of the solubilized metal compound, oxides, chlorides, hydroxides, carbonates, phosphates, carboxylates, etc. are preferably used. Specifically, calcium chloride, calcium hydroxide, manganese acetate, cobalt acetate, cobalt chloride, etc. can be mentioned. Further, the phosphorus compound contained in the polyester (B) of the present invention is a compound containing at least one phosphorus compound in a solubilized state in the polyester (B). Examples of these phosphorus compounds include phosphoric acid, phosphorous acid, trimethyl phosphate, triethyl phosphate, triphenyl phosphate, methyl acid phosphate, ethyl acid phosphate, methylphosphonic acid, and ethylphosphonic acid. etc. Here, the state solubilized in polyester is
Solution haze of polyester excluding the above inert inorganic compounds is 10% or less. The content of the metal or metal compound is determined so that the melt specific resistance of the polyester composition finally obtained by the method of the present invention is 2×10 ⁸ Ω·cm or less, preferably 1×10 ⁸ Ω·cm or less. It is contained in Specifically, it can be obtained by containing 0.015 to 0.3% by weight, preferably 0.02 to 0.25% by weight. In addition, the content of phosphorus compounds is determined by the metals (Mg,
When M represents Ca, Mn, Co) and P represents the phosphorus compound and phosphorus, it is desirable that the molar fraction of M/P is 1.2 or more, preferably 1.5 or more. The polyester composition obtained by the method of the present invention is one in which a polyester resin contains one or more kinds of inert inorganic compounds, metals or metal compounds, and one or more kinds of phosphorus compounds in the above specified amounts. Other additives may be added to this composition as long as the objects of the present invention can be achieved. The polyester composition obtained by the method of the present invention contains the above-mentioned inert inorganic particles and has a solution haze of 20 to 70.
%, and when made into a biaxially stretched film, it forms countless fine surface protrusions, and has surface properties suitable for magnetic tapes and capacitor bases.
In other words, the surface roughness is Ra = 0.020 to 0.060μ (cutoff 0.25mm), and the coefficient of static friction as sliding property is μs
It is more desirable to make fine adjustments so that it shows the range of = 0.4 to 1.0. The method for producing the polyester composition of the present invention will be explained below. First, add polyester resin with an average particle size of 0.1 to 5μ.
The polyester (A) contains an inert inorganic compound, and on the other hand, the polyester resin contains Mg,
Ca, Mn, Co or at least one of these metal compounds is preferably contained in an amount of 0.5 to 1.5% by weight, and at least one phosphorus compound is contained in an amount having a solution haze of 10% by weight.
The composition of the present invention can be obtained by defining the polyester (B) as polyester (B) and then mixing the polyester (B) with this polyester (A). To explain in more detail, the above-mentioned polyester
(A) and (B) are polyesters consisting of dibasic acids and dihydric alcohols or copolymers thereof, and well-known polyester manufacturing methods can be applied. For example, a carboxylic acid containing terephthalic acid as a main component or an alkyl ester thereof and a glycol containing ethylene glycol as a main component are subjected to an esterification or transesterification reaction using a conventional method. After the reaction is completed, polyesters (A) and (B) can be obtained by carrying out a polycondensation reaction using commonly used polymerization catalysts, such as antimony trioxide, antimony acetate, germanium dioxide, titanium compounds, etc. . However, polyester (A) has an average particle size of 0.1 to 5.0, which can be formed by forming protrusions on the film surface and imparting slipperiness by the well-known internal particle method or external particle method, or by a combination of these methods. Inert inorganic particles of μ are contained so that the solution haze is 20 to 70%. On the other hand, polyester (B) contains Mg, Ca, Mn, Co
Or at least one of these metal compounds
The polyester is contained in an amount of 0.5 to 1.5% by weight, preferably 0.7 to 1.2% by weight, with a solution haze of 10% or less. The metal compound may be added to the polyester at any time as long as it is uniformly dispersed in the polyester and the resulting polyester has a solution haze of 10% or less. Alternatively, it may also be used to generate internal particles. It is particularly preferable to add it from the esterification or transesterification reaction to the end of the initial polymerization reaction. Various phosphorus compounds are further added to the polyester (B) in order to stabilize the polycondensation reaction. The amount of these phosphorus compounds added is limited to the amount ratio with the above-mentioned metal or metal compound. That is,
It is necessary to adjust so that M/P≧1.2, preferably M/P≧1.5. When M/P is less than 1.2, even if the amount of metal or metal compound added is 0.5 to 1.5% by weight, the polyester (B ) is not preferable because the effect as a conductive master is lost. The polyester (B) thus obtained has a specific melt resistance of 20
×10 ⁸ Ω・cm, or less, preferably 1.0 × 10 ⁸ Ω・cm
Satisfies the following. The polyester composition of the present invention is based on the above-mentioned polyester (A), and is mixed with 3 to 20% by weight, preferably 5 to 10% by weight of polyester (B), which acts as a conductivity-improving master. The melt specific resistance should be 2.0×10 ⁸ Ω・cm or less, preferably
The resistance is 1.0×10 ⁸ Ω・cm or less. If the polyester (B) is less than 3% by weight, the melting specific resistance of the composition cannot be significantly lowered, and therefore an improvement in casting speed cannot be achieved. On the other hand, if it exceeds 20% by weight, the solution haze of the composition will be less than 20%, and the amount of inert inorganic particles contained in the polyester (A) will be too diluted, resulting in a biaxially stretched film. This is undesirable because the number of surface protrusions decreases and the slipperiness deteriorates. Therefore, the composition of the present invention, which is a mixture of polyester (A) as a base and polyester (B) in an amount of 3 to 20% by weight, preferably 5 to 10% by weight, enables high-speed casting, and is suitable for magnetic tape bases. It is desirable in that it provides a film having surface properties (surface roughness, ease of slipping) suitable for use in other applications. The method for mixing polyester (A) and polyester (B) is not particularly limited as long as a uniform dispersion state can be obtained during melt extrusion. Usually, before melting and forming a film, chips are blended and dried while stirring to obtain a raw material for forming a film. The polyester composition obtained by the method of the present invention can greatly increase the casting speed in electrostatic casting after melt extrusion using the polyester composition as a raw material, and the biaxially stretched film obtained from the polyester composition can be used as a magnetic tape. It had excellent surface characteristics as a capacitor base. The polyester composition obtained by the method of the present invention is used in films such as magnetic tape bases and capacitor bases that require strict surface properties (slip properties, surface roughness). In the present invention, as mentioned above, the film can be manufactured at high speed by mixing a certain amount of highly conductive polyester containing a specific metal with polyester, which originally has excellent surface properties but slow productivity, especially casting speed. It was possible to provide a method for producing a resin composition capable of forming a film and having slipperiness and surface roughness suitable for magnetic tape bases and the like. Note that the characteristic values of the present invention are based on the following measurement method. (1) Average particle size The average particle size is 50% by weight of all particles (30,000 to 50,000 particles) measured by electron micrograph of particles.
It was determined by the equivalent spherical diameter of the particle corresponding to the point.
The equivalent spherical diameter is the diameter of a sphere with the same volume as the particle. (2) Solution haze Add 2.7 g of polymer to 40 c.c. of a 4/6 mixed solvent of tetrachloroethane/phenol and dissolve by heating at 100°C. The solution was collected in a 20 mm cell made of quartz glass,
The haze value was measured using a direct reading haze computer (manufactured by Suga Test Instruments Co., Ltd.) and expressed in %. (3) Melting specific resistance: Place two copper plate electrodes in polyester melted at 290℃, read the current position when applying a high voltage of 1kV, and calculate the specific resistance (Ω cm). demand. (4) Softening point: Hold the crystallized polyester with a needle and measure the softening point at a heating rate of 1°C per minute. (5) Intrinsic viscosity: Measured at 25°C using o-chlorophenol as a solvent. (6) SI casting: A DC voltage is applied between the electrode on the top of the extruded film and the casting drum at the mouth of the extruder. The maximum drum speed is the maximum drum speed when the applied voltage is increased within a range that does not reduce the adhesion between the film and the casting drum surface and does not cause pin-like defects on the film surface, and the casting speed is increased. do. at this time
The value of SI current value is shown in μA. (7) Film haze: Measured according to ASTM-D-1003-52 method. (8) Friction coefficient: Measured according to ASTM-D-1894 using a slip tester manufactured by Toyo Tester.
Note that the coefficient of static friction (μs) and the coefficient of dynamic friction (μd) were used as a measure of the slipperiness of the film. (9) Surface roughness, Ra (μ): Indicates stylus surface roughness,
The values are shown with a cutoff of 0.25 mm and a measurement length of 1.2 mm. (10) Metal analysis: Quantification of Mn, Mg, Ca, and Li elements is
P element was measured by atomic absorption method and colorimetric method. Embodiments of the present invention will be described below based on Examples. Examples 1 to 3, Comparative Examples 1 to 3 100 parts of dimethyl terephthalate, average particle size
0.025 part of 3.0μ calcium carbonate was slurried with 70 parts of ethylene glycol, and a transesterification reaction was carried out in a conventional manner using 0.1 part of manganese acetate as a transesterification catalyst. To this product, 0.04 parts each of antimony trioxide as a polymerization catalyst and 0.04 parts of trimethyl phosphate as a color inhibitor were added and a polycondensation reaction was carried out in a conventional manner.
0.640, a softening point of 261.0°C, a solution haze of 25.0%, and a specific melt resistance of 3.4×10 ⁸ Ω·cm. This polymer was designated as polyester (A). On the other hand, a transesterification reaction was carried out using 100 parts of dimethyl terephthalate and 70 parts of ethylene glycol in a conventional manner using 0.1 part of magnesium acetate as a transesterification catalyst and 0.04 part of tetraethylammonium hydroxide as a softening point lowering inhibitor. . Then add trimethyl phosphate to 0.20
part, antimony trioxide 0.05 part, magnesium acetate
After adding 0.7 parts, the polycondensation reaction was completed by a conventional method, and the intrinsic viscosity was 0.610, the softening point was 258.3℃, and the solution haze was
1.7%, melt specific resistance 0.3×10 ⁸ Ω・cm, M/P=2.1
A polymer [polyester (B)] was obtained. When the amount of polyester (B) added in the above mixed composition of polyester (A) and (B) is as shown in Table 1, the solution haze and solution specific resistance of the polyester composition are as shown in the table. It was hot. Further, the polyester composition was extruded as a sheet through a T-die at an extrusion temperature of 285°C, and an unstretched sheet was obtained by taking it off with a casting drum at 28°C. Incidentally, upon collection, electrostatic casting was performed by applying a DC voltage to the side of the sheet not in contact with the drum. Next, the unstretched sheet was stretched to a longitudinal stretch ratio of 3.2 times and a transverse stretch ratio of 3.4 times, and heat treated at 215°C to obtain a biaxially stretched film with a thickness of 16 μm. Table 1 shows the SI castability and properties of the biaxially stretched film when obtaining this biaxially stretched film. As is clear from Table 1, in Examples 1 to 3, 5 to 20% by weight of polyester (B) was added to polyester (A).
This is a composition obtained by blending, and its solution haze and solution specific resistance satisfy the claims of the present application. As a result, as shown in Table 1, it can be seen that when films are formed using these compositions as raw materials, both the SI castability and the surface properties of the biaxially stretched films are excellent. On the other hand, in Comparative Examples 1 to 3, since the amount of polyester (B) added was not appropriate, either the solution haze or melt specific resistance of the composition did not satisfy the claims of the present application, and as a result, the casting speed or Some of the surface properties of the axially stretched film are poor. 【table】

Claims (1)

[Claims] 1 Polyester (A) containing an inert inorganic compound with an average particle size of 0.1 to 5μ (excluding cases where lithium and phosphorus elements are simultaneously included as internal precipitated particles), a solution haze of 10% or less, and Mg ,
At least one of Ca, Mn, Co or a compound of these metals and at least one phosphorus compound
A method for producing a polyester composition by mixing a polyester (B) containing seeds, characterized in that the mixing ratio of the polyester (B) in the polyester composition is 3 to 20% by weight. A method for producing a polyester composition.