JPS5951571B2 - Processing method for polyester granules - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method for treating polyester granules.

More specifically, the present invention relates to polyester granules characterized in that montan wax salt is closely adhered to the surface of linear saturated polyester granules, which may optionally contain reinforcing materials such as glass fibers. Concerning how to dispose of the body. Linear saturated polyesters, especially polyethylene terephthalate, have excellent chemical and physical properties and are used industrially as fibers, films, engineering plastics, etc., but in recent years, they have been used particularly as engineering plastics. The development is attracting attention.

When linear saturated polyester is used as engineering plastics, the original properties of linear saturated polyester are not sufficient, and various improvements have been made.

For example, by mixing a fine solid inorganic or organic substance with a linear saturated polyester based on terephthalic acid, the rate of resin crystallization in the mold during molding increases, thereby increasing the density of the molded product. It is known that the dimensional stability at high temperatures is improved, the molding cycle is shortened, and the productivity is improved. Known inorganic substances effective as such nucleating agents include, for example, metal oxides, alkaline earth metal salts, talc powder, glass powder, metal powder, etc., which are fine particles of 5 μm or less. As organic substances, long-chain paraffins and salts of higher fatty acids such as suderic acid, behenic acid, and montanic acid are known. Among these, montan wax salt is a particularly useful additive because it not only has a remarkable effect as a nucleating agent, but also improves the mold releasability during molding and the appearance gloss of the molded product.

However, according to the study results of the present inventor, when manufacturing a linear saturated polyester resin composition containing montan wax salt using an extruder, linear saturated polyester, montan wax salt and glass fiber , inorganic solid substances, and other additives are simultaneously put into the extruder hopper in a fixed proportion, and even when kneading and extrusion is attempted, the raw materials do not feed into the screws well, and the amount discharged from the extruder is therefore extremely unstable. It was found that this resulted in poor productivity.

The reason why the extruder screw bite becomes extremely poor in a system that simply contains Montan wax salt is that the Montan wax salt is unevenly dispersed and the concentration exceeds a certain level in the vicinity of contact with the screw at the bottom of the extruder hopper. Part of the montan wax salt dispersed in the screw melts due to the heat from the screw part, causing the so-called bridging phenomenon due to blocking, which causes other raw materials to adhere to each other, making them less slippery and preventing the raw materials from falling freely. Furthermore, the montan wax salt adhering to the screw surface melts and forms a fluid film of montan wax or salt on the screw surface, which causes the raw material falling from the hopper to slip. considered to be a thing.

Naturally, such a decrease in the ability to feed the raw material into the extruder screw becomes more pronounced as the amount of montan wax salt added to the resin composition increases.

Therefore, when adding haemontan wax salt to these resin compositions, first, montan wax salt is extruded in an amount that does not adversely affect the screw biting ability, or simultaneously extruded with other raw materials. Alternatively, extrude it in a system that does not contain montan wax salt and cut it with a cutter after cooling.
A method may be used in which the pellets are formed into pellets, dried, and then mixed with the remainder or the entire amount of montan wax salt in a blender or the like prior to injection molding, and then subjected to injection molding.

However, in the mixture of pellets and montan wax salt, it is desirable that the montan wax salt is uniformly adhered to the surface of the pellets, but in the above method, the particle size of the pellets and montan wax salt, It is difficult to obtain a homogeneous mixture due to differences in quantity, specific gravity, etc. Furthermore, even if the mixture is kept almost uniform immediately after mixing, the adhesion of Montan wax salt is weak and the mixture may transfer to the molding machine hopper during molding. After that, the two components separate, and the problem often occurs that the screw suddenly becomes difficult to penetrate in the middle of molding. Furthermore, if the mixing location and the molding location are different, the montan wax salt often separates during transportation or storage of the mixture and becomes unusable for molding. I can't get a satisfactory result.
The present inventors focused on this point, and as a result of intensive study on a method for uniformly adhering montan wax salt to the surface of polyester granules and maintaining it in a stable state, the inventors of the present invention first coated the surface of polyester granules with inert organic treated with liquid,
The inventors have discovered that this objective can be achieved by sprinkling Montan wax salt on them, and have arrived at the present invention.

That is, the present invention uses 100 parts by weight of a linear saturated polyester having an intrinsic viscosity (measured in an orthochlorophenol solution at 35°C) of 0.4 to 1.2 and a reinforcing material such as glass fiber of 0 to 100 parts by weight.
200 parts by weight of the linear saturated polyester was added to the molding polyester granules, the surface of which was mixed with O.D. per 100 parts by weight of the linear saturated polyester. 01 to 3 parts by weight of at least one inert organic liquid selected from paraffins, silicones, or epoxy plasticizers that have a viscosity of 100 poise or less at 25°C and that do not decompose or evaporate during molding. This is a method for treating polyester granules, which comprises moistening the polyester granules with water and then applying 0.05 to 3 parts by weight of montan wax salt. The linear saturated polyester used in the present invention is mainly a linear polyester formed by the reaction of terephthalic acid or its ester-forming derivative with a glycol having 2 to 10 carbon atoms or its ester-forming derivative, Examples include polyethylene terephthalate, polypropylene terephthalate, polytetramethylene terephthalate, polyhexamethylene terephthalate, polycyclohexane-1,4-dimethylol terephthalate, and polyethylene terephthalate is particularly preferred.

In other polyesters, for example, as an acid component, a part of terephthalic acid (usually 10 mol% or less, preferably 5 mol% or less) is added to other aromatic, aliphatic or alicyclic dicarboxylic acids, such as isophthalic acid, phthalic acid. , naphthalene-2,
6-dicarboxylic acid, naphthalene-2,7-dicanolebonic acid, diphenylene dicarboxylic acid, diphenylene dicarboxylic acid, cyclohexane dicarboxylic acid,
Copolyesters substituted with adipic acid or the like can also be used.

Linear saturated polyesters can be obtained by conventional manufacturing methods.

Also, its intrinsic viscosity (35 in orthothalolophenol solution)
(measured value at °C) is O. 4-1.2, especially 0.5-0
．． It is desirable that it be in the range of 85. When a polyester having an intrinsic viscosity of less than 0.4 is used, the molded product obtained from the composition does not exhibit excellent mechanical and thermal properties and cannot be put to practical use.

Further, if the intrinsic viscosity is greater than 1.2, the melt viscosity is high, so the fluidity during molding is extremely low, and the appearance of the obtained molded product is unfavorable. This tendency is particularly noticeable in systems in which glass fibers are blended into the composition for the purpose of improving the mechanical and thermal properties of the molded product. In this case, it is preferable to use a polyester having an intrinsic viscosity of substantially 0.85 or less. In the present invention, the polyester granules are generally referred to as pellets, chips, etc., and can take various shapes such as cubes, rectangles, cylinders, and others.

Usually molten polyester is extruded into strips, then cubes,
The material used is one cut into a rectangular shape, or one extruded into a strand shape and then cut into a cylindrical shape. The inert organic liquid used in the present invention. Paraffin is a paraffin that maintains fluidity at room temperature, does not decompose itself or evaporate during molding, and does not significantly deteriorate other raw materials in the composition, and has a viscosity of 100 poise or less at 25°C. selected from the following: silicone oils, silicone oils, and epoxy plasticizers. It will be done.

If the viscosity is 100 poise or more at 25°C, the montan wax salt will not adhere uniformly.

Examples of paraffins include liquid paraffins and chlorinated paraffins obtained by fractional distillation of petroleum, carbonization of coal, and other methods, and silicone. Examples of the oil include various silicone oils obtained by hydrolysis of dialkyldichlorosilane. Examples of the epoxy plasticizer include epoxidized soybean oil and epoxidized linseed oil. Among these, paraffins and silicone oils are particularly preferred. The amount of these inert liquids is 0.01 to 3 parts by weight based on 100 parts by weight of linear saturated polyester in the resin composition.
It is preferable to use parts by weight. If this amount is less than 0.01 part by weight, it is difficult to uniformly wet the surface of polyester granules, such as pellets, because of the small amount, and therefore the surface of montan wax salt, which is carried out as the next step, is difficult to wet. Since the sprinkling is not uniform and the adhesion of the montan wax salt to the surface of the polyester granules is weak, the intended effects of the present invention are not sufficiently exhibited. On the other hand, if more than 3 parts by weight is used, the pellets will adhere to each other and cause bridging in the hopper during injection molding, resulting in poor biting into the screw. As a method for uniformly wetting the surface of the polyester granules with these inert organic liquids, for example, the polyester granules are placed in a ribbon mixer, and while mixing, the inert organic liquid is dripped from above: a V-type blender. A method of preparing and mixing polyester granules and an inert organic liquid: arranging polyester granules in a single layer on a belt conveyor, and while slowly transporting the conveyor, spraying from a nozzle of a spraying device installed on the top of the conveyor. Methods include spraying an inert organic liquid uniformly onto the surface of the granules and then receiving the moistened granules in a granule holding tank loaded at one end of a belt conveyor. There is no need to limit the method. The surface-wetted polyester granules are immediately transferred to a mixing device together with Montan wax salt in the next step and mixed.

Mixing is performed until the montan wax salt is uniformly adhered to the surface of the polyester granules. Examples of the mixing device include a V-type blender, a ribbon mixer, a Banbury type kneader, a cedar blade type kneader, and any other mixing device used to uniformly mix powder and granule materials. Furthermore, the above-described apparatus for wetting polyester granules with an inert organic liquid may be used as is, as long as it can be used for both purposes. The montan wax salt used in the present invention is a metal salt produced from an acid mixture of aliphatic monocarboxylic acids having a chain length of 26 to 32 carbon atoms (hereinafter referred to as montanic acid) as a raw material.

Suitable montanwax salts contain as cations metals of group I-111 of the periodic table, such as lithium, sodium,
Contains at least one of potassium, barium, magnesium, calcium, aluminum, etc. These montan wax salts are usually produced by the reaction of montanic acid with 0.2 to 1.0 equivalents of the above metal hydroxides or metal oxides, particularly by the reaction with a solution of caustic soda. Montanic acid sodium salt is effective.

Furthermore, the montan wax salt referred to herein is a partial oxidation of montanic acid in an amount of 0.90 equivalent or less, particularly 0.5 to 0.8 equivalent, of a dihydric alcohol having 2 to 4 carbon atoms in the alkylene group. It includes a mixture of a montanic acid ester and a montanic acid metal salt obtained by stylation and subsequent neutralization with an oxide or hydroxide of the above-mentioned metal.
Examples of the dihydric alcohol used for esterification include ethylene glycol, 1,2- or 1,3-propanediol, and 1,3- or 1,4-butanediol. The amount of montan wax salt deposited on the surface of the polyester granules is 0.05 to 3 parts by weight based on 100 parts by weight of linear saturated polyester in the composition. If the amount of the deposited amount is less than 0.05 part by weight, the effect of the montan wax salt as a nucleating agent, mold release agent, etc. on the composition will be diminished, and it will have no practical meaning. On the other hand, when more than 3 parts by weight is used, the effect as a nucleating agent and mold release agent is about the same as in the case of 3 parts by weight. The screw penetration property during injection molding of the composition becomes extremely poor.
In the present invention, reinforcing materials such as glass fiber, asbestos, glass flakes, carbon fiber, etc. are blended into polyester granules in order to improve the mechanical properties, thermal properties (e.g. heat distortion temperature), etc. of the molded product. Good too.

It is particularly preferable to incorporate glass fiber. The type thereof is not particularly limited as long as it is generally used for reinforcing resins.

In addition, the blending amount is based on 100 parts by weight of polyester.
0 to 200 parts by weight is suitable. For example, in order to improve the properties of the molded product, it is desirable to incorporate a large amount of reinforcing material such as glass fiber, but if more than 200 parts by weight of reinforcing material is blended, the fluidity during molding will be significantly reduced. This makes it impossible to obtain a molded product with a good appearance, and the strength reaches saturation, so it is meaningless. Further, various additives may be added to the polyester granules of the present invention in varying amounts as necessary.

For example, in order to further promote the crystallization effect of the montan wax salt used in the present invention, inorganic substances having a particle size of 5μ or less, such as carbonates of alkaline earth metals (e.g. calcium carbonate, magnesium carbonate, etc.): sulfuric acid Salts (e.g. calcium sulfate): titanium oxide, aluminum oxide,
Metal oxides like zinc oxide: talc, graphite,
Aluminum silicate, etc. may be added, and organic substances having a nucleating action, such as long-chain paraffin, oxalate, stearate, and benzoate, may also be added. Also, flame retardants, such as brominated biphenyl ether, brominated bisphenol A diglycidyl ether, polycarbonate oligomers produced from brominated bisphenol A as raw materials, halogen-containing substances such as red phosphorus, triphenyl phosphate, etc. Phosphorus compounds: Phosphorous mononitrogen compounds such as phosphonic acid amides: Flame retardant aids, such as antimony trioxide, boric acid subsalt, etc.: Inorganic fillers, such as silica, minerals, asbestos, glass powder, potassium titanate, etc. Other additives such as stabilizers, colorants, antioxidants, lubricants, mold release agents, ultraviolet absorbers, and antistatic agents can also be added. Also small amounts of other thermoplastic resins, such as styrene resins, acrylic resins,
Polyethylene, polypropylene, fluororesin, polyamide resin, polycarbonate resin, polysulfone, etc., thermosetting resins, such as phenolic resin, melamine resin, unsaturated polyester resin, silicone resin, epoxy resin, etc.:
Furthermore, a soft thermoplastic resin such as ethylene monovinyl acetate copolymer, polyester elastomer, ethylene-propylene terpolymer, etc. may be added. In the present invention,
Usually, a linear saturated polyester and optionally a reinforcing material such as glass fiber and/or the various additives mentioned above are mixed and extruded in a conventional manner, preferably using an extruder, to form "pellets" of the resin composition. After drying the pellets thoroughly, the surface of the pellets is uniformly wetted with an inert organic liquid, and then montan wax salt is applied.

The polyester granules obtained by the treatment method of the present invention have good screw penetration properties and are particularly useful for injection molding, but are not limited to this injection molding.
It is also useful for molding other thermoplastic resins.

In the case of injection molding, there is no need to particularly heat the mold temperature, but if a mold is preheated to 120-150°C, the crystallization rate will be accelerated by the effect of the nucleating agent, and both the inside and outside will be more stable. This is preferred because a homogeneous molded product can be obtained. The present invention will be described in detail with reference to Examples below.

Example 1 100 kg of polyethylene terephthalate having an intrinsic viscosity of 0.62 dried at 120°C for 5 hours, 40 kg of chopped strands of 3 mm long, and 1 kg of talc were added and mixed in a V-type blender. .

The resulting mixture was melt-kneaded in a 65 mmφ extruder at a cylinder temperature of 280° C., and the threads coming out of the die were cooled and cut to obtain pellets. The pellets were dried with hot air at 150°C for 4 hours, and 40 kg of them were supplied to a ribbon mixer in advance. Then, while operating the mixer, silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd.: KBM503 ) 250 g was added dropwise over 10 minutes, and after the addition was completed, mixing was continued for an additional 5 minutes using a ribbon mixer.

While continuing to operate the ribbon mixer, add 250 g of sodium salt of montanic acid (melting point: 178°C) to the chips. The mixture was sprinkled gradually over a period of 5 minutes, and mixing was continued for an additional 5 minutes. The pellets treated in this manner were received in a bucket cart with casters, and immediately moved to a location approximately 10 meters away where a 5-ounce injection molding machine was located, and the pellets were transported to a location where a 5-ounce injection molding machine was located approximately 10 meters away. Transfer from the bucket to the injection molding machine hopper, and set the cylinder temperature to 275℃.
, injection pressure 800 kg/cm2, mold temperature 140'℃, cooling time 25 seconds, and total cycle 40 seconds.
Fifty shots of a disc having a diameter of mm and a thickness of 2 mm were molded.

The molding is fully automatic at the 5th shot after setting the initial conditions. However, the measurement stability and mold release properties were good.
Continuous molding was possible without any trouble until the end of molding.
The surfaces of the molded products obtained were all flat and very glossy.

Comparative Example 1 40 kg of the glass fiber-containing pellets obtained in Example 1 after being dried with hot air were supplied to the ribbon mixer used in Example 1, and while the pellets were being mixed, sodium salt of montanic acid (melting point 178°C) was added from above. 250 g was gradually sprinkled over a period of 5 minutes.

After further mixing for 10 minutes, the pellets were taken out from the ribbon mixer and transferred to the installation location of the injection molding machine using a bucket cart with casters in the same way as in Example 1. The pellets were taken out from the upper layer and transferred to the injection molding machine hopper. Although molding was carried out under the same conditions as in Example 1, the molded product had poor mold releasability.
The disc was significantly deformed. Therefore, the cooling time was changed to 60 seconds and molding was continued. However, the measurement using the screw was unstable, and even though it was set to the same scale,
Occasionally, a molded product with a slightly shot appearance was obtained, which made fully automatic operation impossible. When attempting to refill the molding machine hopper with the pellets remaining at the bottom of the bucket in order to continue molding, it was noticed that a considerable amount of sodium montanate had separated and remained at the bottom of the bucket. Comparative Example 2 40 kg of the hot-air-dried glass fiber-containing pellets obtained in Example 1 were supplied to the ribbon mixer used in Example 1, and the pellets were mixed. Meanwhile, 1000 g of the silicone oil used in Example 1 was added dropwise and mixed over 40 minutes.

After the dropping was completed, the mixture was mixed for another 20 minutes, and then 250 g of sodium montanate (melting point: 178°C) was sprinkled over the top over a period of 5 minutes, and then mixing was continued for a further 5 minutes. The thus treated pellets were transferred to a bucket as in Example 1, and then transferred to an injection molding machine and molded. When the pellets were transferred from the bucket to the hopper of the injection molding machine, we carefully observed the bottom of the bucket and found that no separation between the pellets and the sodium montanate salt occurred, and that the sodium montanate salt was uniformly adhered to the surface of the pellets. It was kept in good condition. During molding, the pellets bit into the screw very poorly, making molding virtually impossible.

As a result of investigating the cause, it was found that the pellets were forming blocks inside the hopper, preventing them from falling to a part of the screw. Therefore, it was necessary to use a wooden slicing rod with a diameter of 30 mm to continue pushing the pellets from the top of the hopper each time the screw rotated once. The surface of the molded product thus obtained was as good as in Example 1. Example
2.Pour 100 kg of polyethylene terephthalate with an intrinsic viscosity of 0.78, dried at 120°C for 5 hours, and 0.6 kg of aluminum silicate powder into a V-type blender, mix for 5 minutes at 75 revolutions per minute, and mix until homogeneous. A raw material mixture was obtained.

This mixture was quantitatively fed into the extruder hopper at a rate of 833 g/min via an auger feeder. On the other hand, 30 strands consisting of 200 single yarns with a diameter of 9 μm were arranged and the silane-treated glass roving was cut into a fiber length of 6 mm at a rate of 206 g/min using a rotary glass fiber roving cutter installed above the hopper of the extruder. The chopped glass strands were fed into the extruder hopper.

At the same time, the extruder was operated under the same conditions as in Example 1. The pellets thus obtained were dried with hot air at 150°C for 4 hours,
Transfer 50 kg of it to a V-type blender, and transfer 24 kg at the same time.
After adding 0 g of liquid paraffin (grade 1 reagent), a V-type blender was rotated for 20 minutes to uniformly adhere the liquid paraffin to the pellet surface.

Next, 240 g of lithium montanate salt (melting point 198°C
) was added and the V-type blender was rotated again for 20 minutes. The pellets thus obtained were transferred to a bucket under the same conditions as in Example 1, transported to an injection molding machine, and then subjected to molding.

After the pellets were transferred from the bucket to the hopper, no lithium montanate salt powder remained separated at the bottom of the bucket.

Furthermore, both the moldability and the appearance of the molded product were as good as in Example 1.

Example 3 Polyethylene terephthalate with an intrinsic viscosity of 0.59 was
After drying at 0°C for 5 hours, the same glass rope used in Example 2 was coated with an extrusion molding machine in the same manner as electric wire coating so that the glass content was 30% by weight, and then cut into pieces with a diameter of 3 mm. A pellet with a length of 6 mm was prepared.

After drying this pellet at 120℃ for 5 hours, 50k
Transfer g to a V-type blender, and at the same time add 150 g of glycol-type epoxy resin (manufactured by Nagase Sangyo Co., Ltd.) that is liquid at room temperature.
After adding Denacol EX-421), the blender was rotated for 20 minutes to uniformly adhere the epoxy resin to the pellet surface. Then, in a blender, add 120 g of partially esterified montan calcium (0.0 g of montanic acid).
obtained by esterification with 75 equivalents of 1,3-butanediol followed by neutralization with calcium oxide)
was added, and the blender was rotated again for 20 minutes.

The pellets thus obtained were transferred to a bucket under the same conditions as in Example 1, transported to an injection molding machine, and then subjected to molding.

After the pellets were transferred to the hopper of the injection molding machine, the partially esterified montan calcium powder did not remain separated at the bottom of the bucket. Furthermore, both the moldability and the appearance of the molded product were as good as in Example 1.

Claims (1)

[Claims] 1 Linear saturated polyester 100 with an intrinsic viscosity (measured at 35°C in orthochlorophenol solution) of 0.4 to 1.2
Molding polyester granules containing 0 to 200 parts by weight of reinforcing material are coated with 0.01 to 3 parts by weight of 25 parts by weight per 100 parts by weight of the linear saturated polyester.
After moistening with at least one inert organic liquid selected from paraffins, silicone oils, or epoxy plasticizers that have a viscosity of 100 poise or less at ℃ and do not decompose or evaporate during molding, A method for treating polyester granules, which comprises depositing ~3 parts by weight of montan wax salt.