JPH0579103B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a polyester composition, and more particularly to a polyester composition useful for forming a film with few coarse particles and excellent slipperiness, flatness, and abrasion resistance. Regarding the composition. Prior Art and its Problems Polyester, particularly polyethylene terephthalate, has excellent mechanical properties, chemical properties, etc., and is therefore widely used in films, fibers, and the like. In particular, biaxially stretched films of polyethylene terephthalate and polyethylene naphthalate are preferably used in the field of magnetic recording such as audio tapes, video tapes, and computer tapes, which have undergone remarkable development in recent years. However, despite its excellent properties, polyester has poor workability due to poor slipperiness in terms of process passability in the molding process to obtain the above-mentioned molded products, or handleability of the product itself, and its commercial value deteriorates. It is known that undesirable problems such as a decrease in As a method to improve these troubles, as will be described later, many methods have been proposed in which fine particles are contained in polyester to impart appropriate irregularities to the surface of the molded product to improve the surface smoothness of the molded product. Methods for improving the surface properties of polyester include precipitating part or the front part of the catalyst used during polyester synthesis in the reaction process, or adding chemically inert fine particles during or after polyester synthesis. is well known. Carbon black is known as such chemically inert fine particles, and proposals have been made in JP-A-51-52808, JP-A-53-139511, and JP-A-59-71357. And, JP-A-59-
Publication No. 71357 states that normal carbon black is 0.5
It contains volatile content of more than 0.3% by weight, but by heat-treating it in a non-oxidizing atmosphere, the crystal structure can be changed and at the same time the volatile content can be reduced to 0.3% by weight or less. It is explained that it is preferable to use carbon black. However, according to studies conducted by the present inventors, conventional polyester containing carbon black tends to form agglomerated secondary particles due to thermal shock when added during polyester synthesis, and contains many coarse particles due to agglomeration. , is not something to be satisfied with. For this reason, when the molded product is a fiber, thread breakage occurs during processing, and when the molded product is a film, there are high protrusions caused by coarse particles, so there are problems such as dropouts in magnetic recording films. It wasn't something that should have been done. Purpose of the Invention In view of the above-mentioned circumstances, the present inventors conducted intensive research to develop a polyester composition in which carbon black is uniformly and finely dispersed, and found that carbon black having specific characteristics is well dispersed in polyester. It was discovered that the obtained films and fibers had good properties, and the present invention was achieved. Therefore, it is an object of the present invention to provide a polyester composition that contains almost no coarse particles and is useful for producing films with excellent slip properties, flatness, abrasion resistance, etc., or fibers with excellent processability. It's about doing. Structure of the Invention The object of the present invention is to contain 0.05% to 6% by weight of carbon black having the characteristics of an average particle diameter of 15 to 100 mμ, an oil absorption of 60 to 130ml/100g, and a volatile content of 3 to 6% by weight. This can be achieved by using a polyester composition. The unique feature of the present invention lies in the inclusion of carbon black with specific properties in the polyester. The carbon black in the present invention is a carbon black that satisfies the following requirements. First, the average particle diameter is 15 to 100 mμ, preferably 25
~80 mμ. This average particle size is obtained by dispersing carbon black in chloroform using ultrasonic waves.
It is determined by placing it on a sheet mesh covered with carbon-deposited acetyl cellulose film, projecting it with a transmission electron microscope, selecting 2000 particles, measuring their particle diameters, and calculating the number average particle diameter. Second, oil absorption is 60-130ml/100g, preferably
It is 70-120ml/100g. This oil absorption amount is determined by placing 1.00 g of a dry sample of carbon black on a stone with a smooth surface, and adding dibutyl phthalate little by little.
Knead thoroughly with a stainless steel spatula, measure the minimum amount of dibutyl phthalate at which the sample and dibutyl terephthalate form one spherical shape, and convert it to the amount (ml) of dibutyl phthalate per 100 g of carbon black. Thirdly, the volatile content is 3 to 6% by weight, preferably 4 to 6% by weight.
It is 6% by weight. The volatile matter was removed by shaking the dry sample in a platinum crucible with a lid, and heating it at 950°C in an electric furnace.
After heating for 7 minutes, the sample is allowed to cool, and the difference in weight between the samples before and after the heat treatment is calculated as weight %. The carbon black used in the present invention must satisfy all three requirements. If carbon black that does not satisfy any one of these requirements is used, the resulting polyester composition will have a high content of coarse particles due to agglomeration.
The surface of the molded product becomes rough. For this reason, when a polyester composition is formed into a film, the electromagnetic conversion characteristics and dropout of the magnetic tape using the film are poor, and in the case of fibers, thread breakage occurs during processing, and the product appears white. Such disadvantages arise. The carbon black in the present invention is
The manufacturing method is not particularly limited as long as it satisfies all of the above requirements. Examples of methods for producing carbon black include: 1. Furnace incomplete combustion method: natural gas, oil, etc. are incompletely combusted in a furnace to obtain carbon black. 2 Contact incomplete combustion method: Carbon black is obtained by impinging the flame on an iron channel while incompletely burning natural gas, oil, etc. 3. Pyrolysis method: Carbon black is obtained by thermally decomposing natural gas, acetylene gas, etc. at high temperatures. Methods such as the following are known. Among these methods, the furnace incomplete combustion method is preferred as the method for producing carbon black in the present invention from the viewpoint of ease of production and environmental (pollution) control. In order to obtain carbon black having a specific average particle size, oil absorption amount, and volatile content in the present invention,
For example, in the Furness incomplete combustion method,
By optimizing the amount and ratio of raw materials such as natural gas, oil, etc. and air, the temperature at which carbon black is produced,
Methods of controlling residence time, methods of optimizing natural gas, alkali metal salts in oil, aromatic components, etc. as raw materials, methods of optimizing the location and amount of cooling water added to the reactor for reaction termination, etc. It is preferable to take Further, in the contact type (channel type) incomplete combustion method, it is preferable to adopt a method of optimizing the flame temperature, channel temperature, composition of raw materials, etc. In addition, the desired characteristics can be obtained by subjecting carbon black, which has a small volatile content, to post-treatments such as high-temperature oxidation treatment, plasma treatment, chemical treatment, etc. to increase the volatile content. The polyester used in the present invention may be any material as long as it can be formed into a film or fiber, such as polyethylene terephthalate, polytetramethylene terephthalate, poly-1,4-cyclohexylene dimethylene terephthalate, polyethylene-2, Preferable examples include 6-naphthalene dicarboxylate. These polyesters may be homopolyesters as described above, or copolyesters. In the case of copolyester, it is preferable to copolymerize the above-mentioned homopolyester with a small proportion (for example, 20 mol% or less) of a third component, such as diethylene glycol, neopentyl glycol, polyalkylene glycol, etc. Examples include diol components, dicarboxylic acid components such as adipic acid, sebacic acid, phthalic acid, isophthalic acid, and 5-sodium sulfoisophthalic acid, and trifunctional or higher functional carboxylic acid components such as trimetic acid and pyromellitic acid. In the present invention, the content of carbon black in the polyester is 0.05% to 6% by weight, preferably 0.05% to 5% by weight. If the content of carbon black is too low, the slipperiness will be insufficient, and if the content is too high, the density of surface protrusions will increase, making the fibers look whitish. Electromagnetic conversion characteristics of magnetic recording tape using film. Characteristics such as a tendency to worsen are seen, which is not desirable. Various methods can be used to incorporate carbon black into polyester. Typical methods include the following. (a) Carbon black is added to the transesterification reaction product of dimethyl terephthalate and ethylene glycol or the esterification reaction product of terephthalic acid and ethylene glycol, and polycondensation is performed to produce a polyester containing a predetermined amount of carbon black. Method. (a) A method of adding a predetermined amount of carbon black to polyester and kneading it. (c) In the methods (a) and (b) above, a master polymer is produced by adding a large amount of carbon black, and this is kneaded with polyester that does not contain carbon black to form a polyester containing a predetermined amount of carbon black. how to. In addition, when adding carbon black during the production of polyester as in (a) above, ethylene glycol is adsorbed onto the carbon black and kneaded using a roll mill or ball mill, and then ethylene glycol is added to increase the ethylene content of the carbon black. It is preferable to add it to the reaction system as a glycol slurry. If desired, a method in which compounds such as calcium and lithium and phosphorus compounds are added to the reaction system to precipitate particles containing these metals, or a method in which other inert inorganic particles are added may be used in combination, if desired. You can also do it. Effects of the Invention As explained above, according to the present invention, a polyester composition containing no coarse agglomerated particles and containing uniform fine particles can be obtained, and clogging can be reduced in the process of manufacturing molded products from this composition. In addition to eliminating film tearing and thread breakage, it is also possible to obtain a molded product with extremely uniform and fine-grained surface irregularities, especially for magnetic tapes that require easy slippage and the elimination of coarse protrusions. It can be preferably used in the fields of films and false twisted yarn. EXAMPLES The present invention will be described in more detail with reference to Examples below, but the present invention is not limited to the following Examples unless the gist thereof is exceeded. Note that "parts" in the examples mean parts by weight. In addition, the method for measuring physical property values in this specification is as follows. 1. Coarse particles Observe the film under polarized transmitted light using a microscope to check for the presence of foreign particles. The number of aggregated particles of carbon black with a maximum diameter of 5μ or more existing in the area exposed to polarized light was counted, and the following judgment was made. Special grade: Less than 10 aggregated particles/ ^50cm2 1st grade: 10-20 aggregated particles/ ^50cm2 2nd grade: 20-50 aggregated particles/ ^50cm2 3rd grade: 50 aggregated particles Special grade and grade ¹ are used for practical use. 2 Film surface roughness Measured according to JIS B 0601. Tokyo Seimitsu Co., Ltd.
The surface roughness was measured using a stylus-type surface roughness tester manufactured by Co., Ltd. under the conditions of a needle radius of 2 μm and a load of 0.07 g. The center line of the film surface roughness curve is the X axis, and the roughness curve is Y=f(x)
The value (Ra: μ) given by the following formula was taken as the film surface roughness. Ra=1/L∫ ^L ₀ |f(x)|dx (where L=measured length) Reference example: Preparation of ethylene glycol slurry of carbon black 50 parts of various carbon blacks and 50 parts of ethylene glycol were pre-kneaded. Afterwards, the mixture was kneaded repeatedly using a roll mill. Furthermore, 400 parts of ethylene glycol was added, diluted and dispersed in a dispersion mill, and then subjected to a sand mill treatment to sufficiently disperse carbon black. Examples 1, 2 and Comparative Examples 1 to 4 100 parts of dimethyl terephthalate and 70 parts of ethylene glycol (hereinafter abbreviated as EG) were added to a reactor, and further 0.035 parts of manganese acetate tetrahydrate was added, and the temperature was increased by heating. At the same time, methanol was distilled off to complete the transesterification reaction. Next, 0.03 part of trimethyl phosphate and 0.03 part of antimony trioxide were added. Next, 5 parts (0.5% by weight of carbon black to polymer) of the EG slurry of carbon black having the properties listed in the table prepared in the reference example was added under stirring, and then a polycondensation reaction was carried out in a conventional manner to reach the ultimate limit. Polyethylene terephthalate with a viscosity of 0.62 was obtained. The obtained polyester was melt-extruded into a sheet at 290℃ using an extruder, and then longitudinally stretched at 90℃.
Biaxially stretched to 3.5x and 4.0x transverse stretching ratio, and further
Heat setting was performed at 200°C to obtain a film with a thickness of 15μ. The results are shown in Table 1, and Example-
Films 1 and -2 both have fewer coarse particles,
The surface roughness of the film was also flat and good. On the other hand, in Comparative Examples -1 to -4, the characteristics of carbon black were not suitable, and therefore many coarse particles were present and the results were poor. Example 3 A polyester film was obtained in the same manner as in Example 1, except that the amount of carbon black added to the polyester was 6% by weight. Even when a large amount of carbon black was contained, the amount of coarse particles did not deteriorate much and remained good. Although the surface roughness of the film was rough for video use, it was satisfactory for light shielding use, display board use, etc., and was of good quality. The results are shown in Table 1. Example 4 Polyethylene terephthalate (A) having an intrinsic viscosity of 0.62 was obtained in the same manner as in Example 1 except that the amount of carbon black added was 6% by weight in the synthesis of polyester in Example 1. In addition, polyethylene terephthalate (B) having an intrinsic viscosity of 0.62 was obtained in the same manner as in Example-1 except that carbon black was not added in the synthesis of polyester in Example-1. Obtained polyethylene terephthalate (A) and (B)
were fed into an extruder at a ratio of 1:11 in the same manner as in Example-1, formed into a sheet, biaxially stretched, and then heat-set to produce a 12μ thick film with a carbon black content of 0.5% by weight. Obtained. The results are shown in Table 1, and in this master polymer method, Example-
Like No. 1, it was a good film. Examples 5 and 6 and Comparative Examples 5 to 7 Polyethylene terephthalate (B) having an intrinsic viscosity of 0.62 was obtained in the same manner as in Example 1, except that carbon black was not added in the polyester synthesis in Example 1. Next, 99.5 parts of the polyester and 0.5 parts of carbon black powder having the characteristics shown in Table 1 were dried and then placed in a twin-screw extruder (TEX manufactured by Japan Steel Works).
-65) and kneaded at 290°C for a residence time of 5 minutes to obtain a polyester containing 0.5% by weight of carbon black. The obtained polyester was formed into a sheet using an extruder in the same manner as in Example 1, and then biaxially stretched.
Then, it was heat-set to obtain a film with a thickness of 15 μm. The results are shown in Table 1. The films of Examples-5 and -6 had few coarse particles and were good, but the films of Comparative Examples-5, -6 and -7 had many coarse particles and were poor because the characteristics of carbon black were not suitable. . In particular, as is clear from comparing Example-5 and Comparative Examples-5 and -6, even if they have the same particle size, if the oil absorption and volatile content are not appropriate, coarse particles will be formed due to poor dispersion of carbon black. There were many things. Comparative Example 8 A polyester film was obtained in the same manner as in Example 2, except that carbon black having an average particle diameter of 80 mμ, an oil absorption of 80 ml/100 g, and a volatile content of 8% by weight was used. This film had many coarse particles and was defective because the characteristics of carbon black were not suitable. The results are shown in Table 1. 【table】

Claims (1)

[Claims] 1. Average particle diameter 15-100 mμ, oil absorption 60-130 ml/
A polyester composition characterized in that it contains 0.05% to 6% by weight of carbon black having the characteristics of 100 g and a volatile content of 3 to 6% by weight. 2 Carbon black content is 0.05% by weight ~ 5
% by weight of the polyester composition of claim 1. 3. The polyester composition according to claim 1 or 2, wherein the polyester composition is a polyester composition for film production.