Polyethylene terephthalate resin composition

Abstract

Provided is a polyethylene terephthalate resin composition which can be molded under substantially the same conditions as polybutylene terephthalate resin, and further, a polyethylene terephthalate resin composition which allows adjustment of the crystallization rate in a single resin system. [Solution] This polyethylene terephthalate resin composition contains a composition in which 0.01 to 1.0 part by weight of fumed silica (B) is blended with 100 parts by weight of polyethylene terephthalate resin (A), and 0.01 to 2.0 parts by weight of an organic carboxylate metal salt (C), and further contains 0.1 to 2.0 parts by weight of bamboo charcoal (D) having an average particle size of 30 μm or less blended with the above composition.

Description

[Technical field]

[0001] The present invention relates to a polyethylene terephthalate resin composition having a controlled crystallization rate. [Background technology]

[0002] Polyethylene terephthalate resin, a type of thermoplastic semi-aromatic polyester resin, is a resin with a good balance of mechanical properties, transparency, chemical resistance, aroma retention, cold resistance, recyclability, economic efficiency, etc., and is used in large quantities, mainly in fibers, films, sheets, and thin-walled products obtained by processing these, such as clothing items, plastic bags, food containers, beverage bottles, etc. In recent years, with the expansion of beverage bottle production in particular, horizontal recycling, in which beverage bottles are collected and regenerated by processing such as washing, and then expanded into beverage bottle products, is getting on track from an environmental perspective.

[0003] Polyethylene terephthalate resin was invented in 1949, and production has expanded to the present day, mainly for textiles. Although it has a high melting point of 250-260°C, in reality, most of it is used in textiles and water bottles that are used at room temperature. As production and usage increase, it would be desirable from the perspective of the SDGs and from the perspective of the global environment to recycle polyethylene terephthalate resin and convert it into products that take advantage of its high melting point.

[0004] However, compared to polyolefins, polyamide resins, polyacetals, etc., which are widely used for injection molding, polyethylene terephthalate resin products are rarely used for injection molding. The reason is that, although it is a crystalline resin, it has a significantly slower crystallization rate than other crystalline resins such as polyolefins and polyamides, making it unsuitable for molding products, particularly thick products, obtained by injection molding, extrusion molding, press molding, etc. Glass fiber reinforced polyethylene terephthalate resin, which contains 10 parts by weight, preferably 30 to 50 parts by weight of glass fiber, has a high melting point among engineering resins, so the mold temperature when injection molding it is set to 130 to 150 ° C. Even so, it takes 3 to 5 minutes to remove it. Although it may be molded at a mold temperature of 30 to 60 ° C with water cooling, it is necessary to eliminate the warpage of the product by fitting it into a correction jig and performing an annealing treatment. In the end, there is a drawback in that the total cycle is long in the molding of polyethylene terephthalate resin.

[0005] Polybutylene terephthalate resin was introduced in 1970 with the aim of drastically improving the crystallization speed of polyethylene terephthalate resin. Compared to polyethylene terephthalate resin, crystallization proceeds at about three times the speed under the same cooling conditions. Even in the case of glass fiber reinforcement, molding is possible at a mold temperature of 70 to 90 degrees Celsius, and the molding cycle is short. It has excellent electrical properties, mechanical properties, chemical resistance, dimensional stability, colorability, etc. It is particularly used in various parts, especially internal mechanism parts, in the electrical and electronic fields represented by connectors, automobiles and industrial machinery fields such as door handles, office equipment such as personal computers, housings for home appliances, and housing materials. The length (n) of the alkyl group that condenses and polymerizes with terephthalic acid is 2 for polyethylene terephthalate resin and 4 for polybutylene terephthalate resin, making it easier for the molecular chain to rotate, which has resulted in faster crystallization.

[0006] Thus, polybutylene terephthalate resin has expanded in the market in the field of molded products, but there are difficulties in material recycling. Most products are so-called compound materials consisting of glass fiber alone or in combination with inorganic fillers, and in the case of connectors, the concentration of glass fiber and inorganic fillers to be compounded varies depending on the shape and use of the connector, and the colors range from black to multicolored. Furthermore, the flame retardant formulations are mainly halogen-based, and are mixed with non-halogen flame retardant formulations, so even if the products are recovered, separation is difficult. Recycled polybutylene terephthalate resin is limited to in-process blends of the same grade or similar grades.

[0007] On the other hand, the market for polyethylene terephthalate resin is large. A system for the separate collection of used beverage bottles from the city has been established, and the resin has characteristics such as almost the same quality as that of the intrinsic viscosity (IV) value. If this advantage could be utilized to give polyethylene terephthalate resin the same crystallization speed as polybutylene terephthalate, it would have a great impact on preventing global warming and the waste of resources. However, this was not possible with conventional technology.

[0008] Furthermore, polybutylene terephthalate resin, which has replaced polyethylene terephthalate resin, has problems in some applications due to its too fast crystallization speed. In particular, glass fiber reinforced materials have poor product appearance after injection molding. When glass fiber-containing polybutylene terephthalate resin material is injected into a mold, the glass fiber in contact with the mold surface does not shrink, but the matrix polybutylene terephthalate shrinks in volume due to fast crystallization, resulting in the glass fiber floating on the surface. Even if a paint is applied, the roughness of the base affects the paint reflection, which decreases.

[0009] As a countermeasure, it is usually dealt with by blending a polystyrene-based amorphous resin or a polyethylene terephthalate resin with a slow crystallization rate. It is known that mixing this polybutylene phthalate resin and polyethylene phthalate resin causes ester exchange under elapsed time and temperature conditions, resulting in a decrease in heat resistance. For this reason, while the polyethylene terephthalate resin is required to have a crystallization rate similar to that of the polybutylene terephthalate resin, it would be a great advance if the polyethylene terephthalate alone could obtain the moldability and physical properties of the above-mentioned mixture of polybutylene terephthalate and polyethylene terephthalate, compared with the polybutylene terephthalate resin with a crystallization rate that is too fast. However, such control technology has not existed until now.

[0010] An object of the present invention is to develop a polyethylene terephthalate resin composition that can be molded under conditions, such as mold temperature and cooling cycle, that are approximately equivalent to those of polybutylene terephthalate resin, for example in injection molding, and further to develop a polyethylene terephthalate resin composition whose crystallization rate can be adjusted as a single resin system, without the need to blend polyethylene phthalate resin in order to improve the appearance of glass fiber or carbon fiber reinforced materials, which is caused by the excessively fast crystallization rate of polybutylene terephthalate.

[0011] Research into improving the crystallization rate of polyethylene terephthalate resin has been conducted since the birth of polyethylene terephthalate resin. Patent Document 1 shows the results of evaluation of crystallization nucleating agents in terms of the crystallization induction period, half crystallization time, and intrinsic viscosity obtained by optical techniques for samples obtained by melt extrusion of polyethylene terephthalate resin with 1.0% by weight of various nucleating agents. As simple substances that are not effective, Zn powder and Al powder are exemplified. As metal oxides, Fe2O3, TiO2, MnO2, SiO2, and Fe3O4 are exemplified. As inorganic substances, Na2CO3, K2CO3, CaCO3, Zn2CO3, and Mg2CO3 are exemplified. As clay substances, kaolin, acid clay, celite, and clay are exemplified. As organic substances, sodium oxalate, sodium benzoate, sodium phthalate, and sodium naphthalene sulfonate are exemplified. Crystalline polymer polypropylene, nylon, and the like are said to be ineffective. Substances that have been shown to be effective include graphite, carbon black, ZnO, MgO, CaSiO2, talc, calcium oxalate, calcium benzoate, magnesium stearate, calcium tartrate, and zinc salicylate.

[0012] Patent Document 2 shows the results of measuring the crystallization temperature by the DSC method for samples to which 2.0% by weight of various crystallization nucleating agents were added. The crystallization temperature was determined by the exothermic peak when the sample was melted in a nitrogen stream at 300°C for 10 minutes and then cooled at a cooling rate of 10°C / min. A high temperature and a sharp exothermic curve (due to crystallization) indicate a fast crystallization rate. However, a high exothermic peak temperature and a crystallization rate are appropriate when comparing materials of the same type, but are meaningless when comparing different materials, such as polypropylene resin. When comparing materials of the same type, it is important to compare both the sharpness of the exothermic curve and the amount of heat generated, which reflects the degree of crystallization. According to this document, inorganic substances with wide exothermic curves (not capable of forming crystallization nuclei) include talc, TiO2, SiO2, K2CO3, CaCO3, etc. Organic compounds include sodium terephthalate (potassium, calcium), lithium benzoate, and aluminum benzoate. Compounds with sharp exothermic curves include lithium terephthalate, potassium benzoate, and sodium stearate.

[0013] It can be seen that in Patent Documents 1 and 2, some compounds are said to have no effect, while others are said to have an effect, and thus the results are not organized. Patent Documents 1 and 2 also evaluate SiO2, which has the same chemical formula as the fumed silica used in the present invention described below, but both evaluation results state that the effect of SiO2 in accelerating the crystallization rate of polyethylene terephthalate resin is low.

[0014] Patent Document 3 discloses a technique of adding fumed silica to polyethylene terephthalate resin. It states that by adding 0.01 to 1.0% by weight of ultrafine silica particles having an average particle size of 70 nm or less, the transparency of the container obtained by thermoforming the sheet is ensured and slip properties are imparted. Transparency means that the sheet is not crystallized. In other words, it was not known that fumed silica can crystallize polyethylene terephthalate resin until the present invention. [Prior art documents] [Patent documents]

[0015] [Patent Document 1] Special Publication No. 44-7542 [Patent Document 2] Special Publication No. 47-14502 [Patent Document 3] Japanese Patent Application Publication No. 4-136063 Summary of the Invention [Problem to be solved by the invention]

[0016] An object of the present invention is to provide a polyethylene terephthalate resin composition which can be molded under conditions substantially equivalent to those of polybutylene terephthalate resin, and further to provide a polyethylene terephthalate resin composition which allows adjustment of the crystallization rate in a single resin system. [Means for solving the problem]

[0017] The polyethylene terephthalate resin composition of the present invention contains 0.01 to 2.0 parts by weight of an organic carboxylate metal salt (C) in a composition obtained by blending 0.01 to 1.0 part by weight of fumed silica (B) with respect to 100 parts by weight of polyethylene terephthalate resin (A). The polyethylene terephthalate resin composition of the present invention contains 0.01 to 1.0 part by weight of fumed silica (B) and 0.1 to 2.0 parts by weight of bamboo charcoal (D) having an average particle size of 30 μm or less with respect to 100 parts by weight of polyethylene terephthalate resin (A), and contains 0.01 to 2.0 parts by weight of an organic carboxylate metal salt (C).

[0018] The polyethylene terephthalate resin (A) according to the present invention is a recycled polyethylene terephthalate resin. The organic metal carboxylate (C) according to the present invention is a metal benzoate and a metal stearate. When the polyethylene terephthalate resin (A) according to the present invention is a recycled polyethylene terephthalate resin, the organic metal carboxylate (C) is a metal benzoate and a metal stearate.

[0019] The present invention is a polyethylene terephthalate resin composition comprising 40-90% by weight of a polyethylene terephthalate resin composition and 60-10% by weight of glass fiber, and the polyethylene terephthalate resin (A) according to the present invention is a polyethylene terephthalate resin composition comprising 40-90% by weight of a polyethylene terephthalate resin composition and 60-10% by weight of glass fiber. The polyethylene terephthalate resin composition of the present invention is a polyethylene terephthalate resin composition having a difference between a crystallization peak temperature and a melting peak temperature of 45°C or less in a differential scanning calorimeter. The measurement conditions of the differential scanning calorimeter are to heat the polyethylene terephthalate resin to 300°C at a heating rate of 10°C / min in a nitrogen atmosphere to melt the resin, hold for 5 minutes, and then cool to 70°C at a cooling rate of 10°C / min to obtain the crystallization peak temperature from the crystallization exothermic curve, hold at 70°C for 5 minutes, and then heat to 280°C at a heating rate of 10°C / min to obtain the melting peak temperature from the melting endothermic curve. Effect of the Invention

[0020] The polyethylene terephthalate resin composition of the present invention has a high crystallization rate, excellent moldability, and higher heat resistance than polybutylene terephthalate resin. The fumed silica used as a crystallization promoter in the present invention is ultrafine particles, and the amount added is very small. The amount of organic carboxylate metal salt added and the amount of bamboo charcoal powder added as a crystallization rate regulator are also small, so that molded products with little deterioration in mechanical properties and thermal stability during processing can be obtained. In addition, a polyethylene terephthalate resin composition containing 40 to 90% by weight of a resin composition and 60 to 10% by weight of glass fiber has mechanical strength and thermal properties equal to or greater than those of glass fiber reinforced polybutylene terephthalate resin. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] The polyethylene terephthalate resin composition of the present invention will be described in detail below with reference to examples. The scope of the present invention is not limited by these examples. The polyethylene terephthalate resin (A) used in the present invention is a polycondensate or a copolymer mainly composed of terephthalic acid or its ester-forming derivative as a dicarboxylic acid component and ethylene glycol or its ester-forming derivative as a diol component. It is produced by a known method and has a high melting point of 240 to 260°C. The molecular weight varies depending on the application, but the intrinsic viscosity (IV value) is 0.5 to 0.6 for fibers, around 0.7 for sheets for packaging containers, and 0.7 to 1.2 for bottles. The present invention can be applied to polyethylene terephthalate resins of any intrinsic viscosity.

[0022] Here, recycled polyethylene terephthalate resin can be used in two ways: polyethylene terephthalate resin generated during the manufacturing process, such as non-standard products and trimmings from sheet molding, is crushed and used, or polyethylene terephthalate resin collected from the market is processed for reuse. In the case of polyethylene terephthalate resin, most of it is collected after being distributed in the market as food packaging sheets and beverage bottles. In the case of beverage bottles, the collected products from the market are classified and sorted according to the rank of contamination. Foreign matter contamination is monitored using infrared spectroscopy to select only polyethylene terephthalate resin. Bottle caps are made of polyethylene or polypropylene, so they are removed, and labels are also peeled off and separated. The resin is then cut into flakes using a mechanical cutter.

[0023] Next, the flakes are washed with a specified alkaline aqueous solution to separate out the pollutants present in the market. After that, they are neutralized, washed with water, vacuum degassed and dried, and then shipped as flakes. In other cases, they are melt extruded using an extruder to make them the same size as virgin polyethylene terephthalate resin pellets. The molecular weight is reduced by heat and light during the molding stage and in the market. In such cases, methods such as solid phase polymerization are used to adjust the degree of polymerization. In addition, to adjust the molecular weight (intrinsic viscosity IV value), methods such as mixing with polyethylene terephthalate resin with a high IV value and reacting with a chain extender in the extruder to increase the IV value are also used.

[0024] The present invention can be applied to any recycled polyethylene terephthalate resin. In general, it is preferable in terms of dispersion to prepare a high-concentration master batch with a polyethylene terephthalate resin having a slightly lower molecular weight of 0.5 to 0.7 and mix it with a polyethylene terephthalate resin having a high IV value, rather than mixing it directly with a polyethylene terephthalate resin having a high IV value. It can also be applied when using recycled polyethylene terephthalate resin as an alloy resin material, and in that case, the crystallization speed of the polyethylene terephthalate resin is sometimes preferred, and the present invention is applied. The present invention can ensure improvement of the molding cycle in polymer alloys having high strength, precision, and high impact resistance with polyphenylene ether resin, polyphenylene sulfide resin, polystyrene resin, ABS (acrylonitrile butadiene styrene) resin, etc.

[0025] The fumed silica (B) used in the present invention is a dry silica (vapor phase silica, pyrolytic silica) obtained by the combustion reaction of a silicon compound. Methods for producing silica by a dry method include flame hydrolysis, arc, and plasma methods, but the currently industrially mainstream production method is flame hydrolysis. In the flame hydrolysis method, a silicon compound, particularly a silicon halide, generally a silicon chloride, usually purified silicon tetrachloride, is produced by burning and hydrolyzing it in high-temperature (usually 1000°C or higher) oxygen and hydrogen flames. Since the gas mixture containing vaporized silicon tetrachloride (boiling point 59°C) is uniform, the silica produced in this way becomes an aerosol state consisting of very uniform and uniform high-purity amorphous silica fine particles, and since this state appears like a mist, it is called fumed silica.

[0026] Fumed silica (B) is manufactured by a known dry method. Compared to other silicas, non-fumed silica has extremely small primary particles of several nm to several tens of nm, and these primary particles aggregate together like beads to form nano-sized secondary particles. They are characterized by extremely strong mutual cohesive forces.

[0027] The particle diameter of the fumed silica used in the present invention is very fine, which is strongly related to its strong cohesive force. Primary particles with a diameter of about 5 to 50 nm are aggregated into beads-like aggregates with a particle diameter of about 100 to 400 nm due to hydrogen bonds and entanglements between particles caused by silanol groups on the surface, and these aggregates become secondary particles. The secondary particles further gather to form bulky agglomerated particles.

[0028] The fumed silica used in the present invention may be hydrophilic or hydrophobic. When using hydrophilic fumed silica, especially when using it to prepare a master batch of polyethylene terephthalate resin and high concentration hydrophilic fumed silica, a silane coupling agent may be used in combination. Fumed silica has extremely low hygroscopicity compared to other amorphous silicas, and the amount of fumed silica blended in the present invention is extremely small, so it has little effect on polyethylene terephthalate resin.

[0029] In Japan, for example, fumed silica is manufactured at the Yokkaichi Plant, and many grades are sold by Nippon Aerosil Co., Ltd. In addition, some fumed silica grades have passed the U.S. Food and Drug Administration (FDA), making them suitable for a wide range of applications.

[0030] The amount of fumed silica added is in the range of 0.01 to 1.0 parts by weight relative to 100 parts by weight of polyethylene terephthalate resin. If the amount added is less than 0.01 part by weight, the crystallization promotion effect is not obtained, and even if the amount added exceeds 1.0 part by weight, the effect does not improve proportionally, and the crystallization promotion effect reaches a plateau.

[0031] The organic carboxylate metal salt (C) used in the present invention is a metal salt of a carboxylic acid (or a derivative thereof) having a hydrocarbon group having 2 to 30 carbon atoms, which belongs to Groups 1 and 2 of the Periodic Table. Here, the hydrocarbon group includes, for example, an alkyl group, and a cyclic hydrocarbon group having a cyclo ring or a benzozene ring. Among these, an alkyl group and an aryl group are preferred. Specific examples of the metal stearates include sodium stearate, potassium stearate, magnesium stearate, lithium stearate, and calcium stearate. Specific examples of the metal montanates include sodium montanate and magnesium montanate. Specific examples of the metal aromatic carboxylates include sodium benzoate, potassium benzoate, calcium benzoate, and lithium terephthalate. Among the metal organic carboxylates, sodium stearate and potassium stearate are preferred, and among the metal aromatic carboxylates, sodium benzoate and potassium benzoate are particularly preferred.

[0032] In the present invention, these organic carboxylates may be used alone or in combination of two or more. These organic carboxylates have been studied in the past as nucleating agents for polyethylene terephthalate, but the crystallization rate of these metal salts has not yet reached the same level as that of polybutylene terephthalate resins that can replace them.

[0033] The amount of the organic carboxylate metal salt added is preferably 0.01 to 2.0 parts by weight per 100 parts by weight of the polyethylene terephthalate resin. If the amount is less than 0.01 part by weight, the effect as a crystallization promoter is insufficient, and if the amount is more than 2.0 parts by weight, the effect is the same and it is wasted.

[0034] Bamboo charcoal (D) is a powder of bamboo charcoal with an average particle size of 30 μm or less. There is no particular restriction on the type of bamboo used as the raw material, but it can be madake, moso bamboo, atashitake, mechiku (black bamboo), hoteichiku (Cloth bamboo), shihochiku (square bamboo), touchiku (Chinese bamboo), kumazasa (big bamboo), kushimazasa (Chishima bamboo), miyakozasa (Miyako bamboo), etc. These bamboos are heat-treated, crushed, and classified at 600°C or higher, preferably 800°C or higher, in an earthen kiln, rotary kiln, or double kiln method. There is edible bamboo charcoal. It is treated at a high temperature until lignin is decomposed and burned and no residue remains. The average particle size of bamboo charcoal depends on the conditions of the combustion furnace, but it is generally 10 μm or less for edible use and 25 μm for industrial use. It can be used as a crystallization promoter in the present invention.

[0035] The amount of bamboo charcoal to be mixed is 0.1 to 2.0 parts by weight per 100 parts by weight of polyethylene terephthalate resin. It is preferably 0.05 to 2.0 parts by weight. If it is less than 0.1 parts by weight, there is no effect, and even if it is mixed in excess of 2.0 parts by weight, the effect remains the same. Rather, it becomes an obstacle in color matching because the black color becomes darker.

[0036] The reasons why it is preferable to use bamboo charcoal in combination are 1) it is convenient for adjusting the crystallization rate, and 2) it has an antistatic effect when blending fumed silica with resin, stabilizing the kneading process. The reason for 1) is that, as mentioned above, the crystallization rate of polybutylene terephthalate is very fast, which can cause the appearance to deteriorate, especially in glass fiber reinforced materials. As a countermeasure, bamboo charcoal can be added to a low concentration blend of fumed silica to adjust the crystallization rate.

[0037] The inventors focused on bamboo charcoal while investigating composite resins with biomaterials. They had thought that a combination with recycled polyethylene terephthalate would be environmentally friendly, but they had not expected that bamboo charcoal would have the effect of promoting crystallization. When recycled polyethylene terephthalate without bamboo charcoal was kneaded in a Plastomill kneading device, a molten material like starch syrup flowed out of the device. On the other hand, when bamboo charcoal was added, the molten material did not flow, and crystallization progressed as soon as it was scraped out of the device and exposed to room temperature.

[0038] The melt kneading is carried out using a known kneading device that is widely used in the production of thermoplastic resin compositions. Specific kneading devices include a Brabender, a Banbury mixer, a single screw extruder, a twin screw extruder, a roll, a kneader, and the like. Among them, melt kneading using a twin screw kneader that is excellent in industrial cost and shear kneading ability is preferred. Furthermore, it is more preferred if the twin screw extruder is equipped with a plurality of feed ports and a raw material supply device (feeder). Depending on the form of the raw material, the supply accuracy of the feeder, the kneading order, and the like, it is possible to supply each component independently without mixing in advance, or to mix only some of the components in advance and supply them. In addition, a method of using a master batch containing fumed silica, an organic carboxylate metal salt powder, or bamboo charcoal powder is also preferred because it can reduce the deterioration of the working environment due to the scattering and dust generation of powder and has an excellent powder dispersion effect.

[0039] In the polyethylene terephthalate resin composition of the present invention, inorganic fillers and reinforcing materials such as mica, talc, clay, graphite, calcium carbonate, calcium sulfate, titanium oxide, glass beads, glass fibers, carbon fibers, etc. may be blended to the extent that the object of the present invention is not impaired in order to improve the physical properties, etc. In particular, glass fibers are preferred because they can impart high strength and toughness, high heat resistance including low creep at high temperatures, and further excellent performance such as abrasion resistance, chemical resistance, and dimensional stability. In the present invention, 60-10% by weight of glass fiber is blended with 40-90% by weight of polyethylene terephthalate resin composition. The blending ratio is determined in consideration of the strength, heat resistance, etc. of the target product. The range of 15-50% by weight, with 30% by weight as the center, is preferred.

[0040] In addition, various additives may be blended within the scope of the present invention, specifically, various antioxidants such as hindered phenols, various heat stabilizers such as phosphite, various release agents such as olefin waxes and fatty acid esters, dispersants, thickeners, plasticizers, antiblocking agents, antibacterial and antifungal agents such as phenols, anionic, cationic and nonionic antistatic agents, colorants, etc., and a plurality of these additives may be blended together.

[0041] The polyethylene terephthalate resin composition of the present invention can be molded by a conventional molding machine for thermoplastic resins. When conventional glass fiber reinforced polyethylene terephthalate is injection molded, the mold temperature is set to 130°C to 150°C, but the present invention allows molding under the same mold temperature conditions of 80°C to 100°C as polybutylene resin.

[0042] The present invention will now be described in more detail with reference to examples. The raw materials used in the examples and comparative examples are as follows. (A) Polyethylene terephthalate resin: crushed flakes from recycled beverage bottles, manufactured by Kyoei Sangyo Co., Ltd., IV value 0.68 (B) Fumed silica: Aerosil RY200L, manufactured by Nippon Aerosil Co., Ltd. Dimethylpolysiloxane surface treatment Primary particle diameter 12nm, specific surface area 100±20m 2 / g (C) Organic carboxylate metal salt Sodium benzoate: Fujifilm Wako Pure Chemical Corporation Reagent Sodium stearate: Fujifilm Wako Pure Chemical Corporation Reagent (D) Bamboo charcoal: Bamboo charcoal powder from Bamboo charcoal village (Miyazaki Prefecture) (edible bamboo charcoal fine powder) Average particle size 5.46μm (median diameter 5.21μm) Particle size measurement: Horiba Laser diffraction / scattering particle size distribution measurement Equipment LA-950V2. Polybutylene terephthalate resin: Novaduran 5010R5, manufactured by Mitsubishi Chemical Corporation

[0043] <Crystallization temperature / melting temperature measurement> The crystallization temperature was measured by a thermal analysis method. Using a Shimadzu Corporation DSC-60 differential scanning calorimeter, the sample was melted in a nitrogen stream at 300°C for 5 minutes, then cooled at a cooling rate of 10°C / min, and the crystallization start temperature, crystallization peak temperature, and crystallization end temperature were obtained when the sample crystallized within the time period up to 70°C. Next, the sample was held at 70°C for 5 minutes, and then heated at a heating rate of 10°C / min, and the melting start temperature, melting peak temperature, and melting end temperature were obtained when the sample melted within the time period up to 280°C. Generally, as an index of crystallization rate, the distance (H) from the crystallization start temperature to the crystallization end temperature width (W) is measured from a chart, and it is said that the larger the H / W, the faster the crystallization rate. The problem is that there is a considerable amount of human error when measuring from a chart, so this should only be used as a reference. Similarly, the degree of crystallization is sometimes expressed as the area ratio of the crystallized region, but in the case of polyethylene terephthalate resin, this is not recommended because the area of ​​the amorphous region is unclear. Therefore, in the case of crystalline resins, it is generally believed that when the difference between the melting point and the crystallization temperature is large, the rate at which crystallization can occur is high, and there is a nucleating agent effect. Since both the crystallization peak and the melting peak are indicated digitally and there is no artificial judgment, the temperature difference between the melting peak temperature and the crystallization peak temperature was evaluated as the crystallization promotion effect.

[0044] <Observation of demolding and crystallization during press molding> The press formability was evaluated by the following method using two mini test presses manufactured by Toyo Seiki Seisakusho Co., Ltd. (Hot pressing process) The resin was filled into a brass mold measuring 85 mm x 50 mm x 2 mmt, the top and bottom were covered with ferroplates (stainless steel glossy plates), and the mold was pressed at a press temperature of 270°C for 6 minutes at a pressure of 3 MPa for 1 minute. (Cooling press process) The resin was set in a press heated to 140°C for 10 seconds and then transferred to a water-cooled press and pressed at 3MPa. The adhesiveness of the pressed resin was checked when peeling it off from the ferro plate. If the adhesiveness was strong, crystallization had not progressed.

[0045] A piece of 50 mm x 25 mm x 0.3 mm was cut from the sheet obtained through the pressing process, placed on a U-shaped box of a stainless steel U-shaped heat resistance evaluation jig with a support distance of 30 mm, and placed in a heating oven at 220°C to observe the deformation. EXAMPLES

[0046] To 100 parts by weight of polyethylene terephthalate resin, 0.1 parts by weight of fumed silica, 0.3 parts by weight of sodium benzoate, and 0.4 parts by weight of sodium stearate were added, and the mixture was melt-kneaded for 10 minutes at a temperature of 280°C and a rotation speed of 100 rpm using a Labo Plastomill 4C150 (manufactured by Toyo Seiki Seisakusho Co., Ltd.) to prepare a kneaded sample. The cylinder block at the front of the Plastomill device was removed, and the molten polyethylene terephthalate resin was sampled. When the cylinder block was removed, the molten material turned white, and it was confirmed that the crystallization rate was fast. Regarding the cooling time and demolding in the press molding, it was confirmed that the resin was removed from the press mold after 15 seconds of cooling. Next, the press-molded product was evaluated for heat resistance at 220°C, and did not fall off the jig even after 30 minutes. The results of differential scanning calorimetry (hereinafter also referred to as "DSC") are summarized in Table 1. In Table 1, polyethylene terephthalate resin is referred to as "PET resin" and polybutylene terephthalate resin is referred to as "PBT resin."

[0047] The resin composition of Example 1 has a temperature difference between the melting peak temperature and the crystallization peak temperature of 34.1° C. Since the temperature difference of the polybutylene terephthalate resin (PBT resin) given as a reference example is 34.6° C., it was found that the polyethylene terephthalate resin composition of Example 1 has approximately the same crystallization rate as the polybutylene terephthalate resin.

[0048] [Table 1] EXAMPLES

[0049] A kneaded sample was prepared under the same conditions as in Example 1, except that the amount of fumed silica added was 0.5 parts by weight. In this example, the front cylinder block of the Plastomill device was removed after kneading, and an attempt was made to sample the molten polyethylene terephthalate resin, but it instantly turned white. Crystallization progressed during hot press molding, and there was no deformation when it was removed from the mold. Next, the heat resistance of the press molded product was evaluated at 220°C, and it did not fall off the jig even after 30 minutes.

[0050] The resin composition of Example 2 has a temperature difference between the melting peak temperature and the crystallization peak temperature of 33.5° C. Since the temperature difference of the polybutylene terephthalate resin (PBT resin) given as a reference example is 34.6° C., the polyethylene terephthalate resin composition of Example 2 is faster than the polybutylene terephthalate resin. EXAMPLES

[0051] A kneaded sample was prepared under the same conditions as in Example 1, except that the amount of fumed silica added was 0.05 parts by weight, sodium benzoate and sodium stearate were 0.3 parts by weight and 0.4 parts by weight, respectively, and bamboo charcoal powder was 0.5 parts by weight. In this example, too, the front cylinder block of the plastomill device was removed after kneading, and the molten polyethylene terephthalate resin was sampled. The color of the molten material containing the bamboo charcoal powder was black, but crystallization had progressed during sampling. Crystallization progressed during hot press molding, and there was no deformation when it was removed from the mold. In the heat resistance evaluation at 220°C of the press molded product, it did not fall off the jig even after 30 minutes.

[0052] The resin composition of Example 3 has a temperature difference between the melting peak temperature and the crystallization peak temperature of 39.5° C. The temperature difference of the polybutylene terephthalate resin (PBT resin) given as a reference example is 34.6° C., which shows that the polyethylene terephthalate resin alone can be used to adjust the crystallization rate in fields where a slower crystallization rate is required for polybutylene terephthalate resin depending on the application. EXAMPLES

[0053] A mixture of 70% by weight of 0.5 parts by weight of fumed silica, 0.3 parts by weight of sodium benzoate, and 0.4 parts by weight of sodium stearate per 100 parts by weight of polyethylene terephthalate resin was fed from the main hopper of a co-rotating twin-screw kneading extruder HK-25D (manufactured by Parker Corporation), and 30% by weight of glass fiber (CS 3PE-044S manufactured by Nitto Boseki Co., Ltd.) was fed from the side feeder of the extruder. The kneading conditions were as follows: cylinder temperature 250°C, screw rotation speed 150 rpm, feed rate 7.0 / hour, and the molten strand extruded from the die was cooled on a belt conveyor with three air-cooling fans attached, and cut into pellets by a pelletizer.

[0054] The distance from the cooling belt conveyor to the pellet cutter was 1,100 mm, but the molten strand was observed to crystallize from approximately the midpoint of the belt conveyor. The strand did not hang down until it reached the pellet cutter. The results of differential scanning calorimetry (DSC) of the pellets of Example 4 are shown in Table 2. In Table 2, polyethylene terephthalate resin is referred to as "PET resin." As shown in Table 2, the temperature difference between the melting peak temperature and the crystallization peak temperature was 37.31°C.

[0055] Next, the pellets were pre-dried at 120°C for 6 hours, and then injection molded using an injection molding machine (electric injection molding machine NEX140 manufactured by Nissei Plastic Industrial Co., Ltd., clamping force 140tf, screw diameter 40φ full flight screw). The injection molding and mold conditions were as follows: cylinder set temperature 270°C, mold set temperature 85°C, injection pressure 93MPa, injection time 2.3 seconds. The mold used was JIS K 7139 Type A (wall thickness 4mm, 2-piece multipurpose test piece). Under these conditions, 30 shots were molded with cooling times of 30 seconds, 20 seconds, and 15 seconds, and the molded products were able to be removed without any problems.

[0056] The flexural modulus and flexural stress of the molded product were determined using a bending test JIS K 7171;2016 (Shimadzu Corporation Autograph AGX-50kNV, load cell capacity 50kN, speed 2mm / min). The flexural modulus and flexural stress are shown in Table 2. Furthermore, the temperature at which the deflection reached 0.34 mm was determined using the heat distortion temperature JIS K7179-1,2 2015 (HDT test device manufactured by Toyo Seiki Co., Ltd.) under the conditions of a test start temperature of 30°C, a heating rate of 120°C / hour, and a bending stress of 1.80 MPa. The results are shown in Table 2.

[0057] Example 1 shows that injection is possible at a mold temperature of 85°C, whereas conventional molding of glass fiber reinforced polyethylene phthalate requires a mold temperature of 130 to 150°C. The cooling time is shortened. The physical properties of the molded product are higher than those of polybutylene terephthalate. EXAMPLES

[0058] A mixture of 0.5 parts by weight of fumed silica, 0.3 parts by weight of sodium benzoate, 0.4 parts by weight of sodium stearate, 0.5 parts by weight of bamboo charcoal powder, 0.1 parts by weight of bamboo charcoal powder, and 70% by weight of glass fiber was mixed with 30% by weight of polyethylene terephthalate resin. The product was obtained by the same kneading and injection molding as in Example 4. The temperature difference between the melting peak temperature and the crystallization peak temperature in differential scanning calorimetry (DSC) was 36.72°C. In this example, the product was obtained without any problems when the cooling removal time in injection molding was 30 seconds, 20 seconds, or 15 seconds. The flexural modulus, flexural stress, and heat distortion temperature are shown in Table 2. It was found that the heat distortion temperature was better when bamboo charcoal powder was mixed.

[0059] [Table 2]

[0060] Comparative Example 1 The polyethylene terephthalate used in Example 1 was melt-kneaded in a plastomill at a temperature of 280°C and a rotation speed of 100 rpm for 10 minutes, and then the cylinder block in front of the plastomill device was slid to remove it, and the molten polyethylene terephthalate resin dripped from the gap like a syrup. The molten product was transparent. In the press molding, the molded product was soft due to insufficient crystallization, and the molded product adhered to the mold and ferro plate, and the sheet molded product was deformed when removed from the mold. It took 240 seconds to be removed stably. The heat resistance evaluation at 220°C of the obtained press molded product was that it fell off 15 seconds after being set on the jig. The temperature difference between the melting peak temperature and the crystallization peak temperature in differential scanning calorimetry (DSC) was 62.7°C, which shows that the crystallization rate is extremely slow.

[0061] Comparative Example 2 0.05 parts by weight of fumed silica was added to 100 parts by weight of polyethylene terephthalate resin, and the mixture was melt-kneaded for 10 minutes at a temperature of 280°C and a rotation speed of 100 rpm using a lab plastomill to prepare a kneaded sample. The mixture was crystallized when removed from the plastomill device. It was found that crystallization of polyethylene terephthalate resin is promoted with a very small amount of addition. The heat resistance evaluation at 220°C of the obtained press molded product showed that it did not fall off even 30 minutes after being set on the jig. The temperature difference between the melting peak temperature and the crystallization peak temperature in differential scanning calorimetry (DSC) was 48.4°C, which is lower than that of polybutylene terephthalate resin (PBT resin). The results of DSC and other measurements for Comparative Examples 1 and 2 are summarized in Table 1.

[0062] Comparative Example 3 The same experiment was carried out except that 70% by weight of polyethylene terephthalate resin was fed from the main hopper of the same direction twin-screw kneader of Example 4 and 30% by weight of glass fiber was fed from the side feeder. Here, the strand was drawn down by its own weight from the air-cooled belt conveyor. The temperature difference between the melting peak temperature and the crystallization peak temperature of the differential scanning calorimetry (DSC) was 54.76°C. The pellets were subjected to injection molding in the same manner as in Example 5. Since the cooling time of 30 seconds was not sufficient to solidify when the mold was opened and the test piece was stuck to the mold, a release agent was applied for each shot while molding, but it was judged that a cooling time of 30 seconds was not possible. Therefore, the time was extended to 120 seconds, but the same results were obtained.

[0063] Therefore, while adjusting the holding pressure, samples were taken out within the range that could be removed within a cooling time of 50 seconds. The flexural modulus, flexural stress, and heat distortion temperature were measured for test pieces that were removed and left to stand at room temperature and moist conditions for one week, and for test pieces that were annealed at 130°C for three hours. The results are shown in Table 2. The heat distortion temperature for the unannealed sample was extremely low at 80.8°C, and even for the annealed sample it was 195°C, which is lower than in Examples 4 and 5.

[0064] [Reference example] As a reference example of Examples 1 and 2, polybutylene terephthalate resin (PBT resin) was press molded in the same manner as in Example 1, and the press moldability and heat resistance of the press sheet were evaluated. The sheet molded product was deformed when removed from the mold. The heat resistance evaluation at 220°C of the obtained press molded product showed that it fell off 10 seconds after being set on the jig. The measurement results of differential scanning calorimetry (DSC) are shown in Table 1, and it was shown that the melting temperature was lower than that of polyethylene terephthalate and the sheet could not withstand the heat resistance test. [Industrial Applicability]

[0065] As described above, it has been found that the polyethylene terephthalate resin composition of the present invention has a high crystallization rate, excellent moldability, and high heat resistance, and is completely differentiated from conventional polyethylene terephthalates. Although polyethylene terephthalate has a high melting point, it is not widely used in industrial fields where heat resistance is required. The reason for this is that it has an extremely slow crystallization rate, making it less suitable for injection molding, which is often used for industrial parts, and has low heat resistance. Polyester is often used for textiles and water bottles, but in addition to horizontal expansion of recycling, up-recycling is also required from the global environmental perspective. Given that the present invention can procure raw materials from the abundant textile and bottle recycling market, the value of using the present invention is increasing.

Claims

1. A polyethylene terephthalate resin composition comprising a composition in which 0.01 to 1.0 part by weight of fumed silica (B) is blended with 100 parts by weight of polyethylene terephthalate resin (A), and the composition further contains 0.01 to 2.0 parts by weight of a combination of a metal salt of benzoic acid and a metal salt of stearate.

2. The polyethylene terephthalate resin composition according to claim 1, wherein the polyethylene terephthalate resin (A) is a recycled polyethylene terephthalate resin.

3. A polyethylene terephthalate resin composition comprising 40 to 90 weight percent of the resin composition described in claim 2 and 60 to 10 weight percent of glass fiber.

4. A polyethylene terephthalate resin composition comprising 100 parts by weight of polyethylene terephthalate resin (A), 0.01 to 1.0 parts by weight of fumed silica (B), and 0.1 to 2.0 parts by weight of bamboo charcoal (D) having an average particle size of 30 μm or less, and further comprising 0.01 to 2.0 parts by weight of an organic carboxylic acid metal salt (C).

5. The polyethylene terephthalate resin composition according to claim 4, wherein the polyethylene terephthalate resin (A) is a recycled polyethylene terephthalate resin.

6. A polyethylene terephthalate resin composition comprising 40 to 90 weight percent of the resin composition described in claim 5 and 60 to 10 weight percent of glass fiber.

7. 6. The polyethylene terephthalate resin composition according to claim 4, wherein the organic metal carboxylate (C) is a combination of a metal benzoate and a metal stearate.

8. A polyethylene terephthalate resin composition comprising 40 to 90 weight percent of the resin composition according to claim 1 or 4 and 60 to 10 weight percent of glass fiber.