JP2016199608A - Highly crystallized polyethylene terephthalate composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly crystallized polyethylene terephthalate composition which hardly deforms thermally, is excellent in impact resistance, has glossiness, and can be easily produced.SOLUTION: The highly crystallized polyethylene terephthalate composition according to the present invention is obtained by injection molding a kneaded material using a metallic mold heated to 110-180°C, the kneaded material contains a thermoplastic resin (component A) containing 50-95% of polyethylene terephthalate, 5-70% of an inorganic filler (component B) with respect to the polyethylene terephthalate, 1-3% of metal soap (component C) containing an alkyl group structure having the number of carbon bonds of 14 or more with respect to the weight of the component A, or 1-10% of a fatty acid ester (component D) containing an alkyl group structure having the number of carbon bonds of 14 or more with respect to the weight of the component A.SELECTED DRAWING: None

Description

  The present invention relates to a highly crystallized polyethylene terephthalate composition that is resistant to thermal deformation, has excellent impact resistance, and is glossy.

  Polyethylene terephthalate is widely used as a fiber, film, and sheet material because of its excellent mechanical strength, heat resistance, chemical resistance, and the like. Polyethylene terephthalate is not suitable for injection molding or extrusion molding because of its low melt viscosity and low crystallization rate, and many molded products containing glass fibers as a reinforcing material are on the market.

  The polyethylene terephthalate molded product containing the glass fiber has a problem that the glass fiber is exposed as its surface is worn. Therefore, Patent Document 1 proposes that polyethylene terephthalate or specific polyethylene terephthalate contains an inorganic compound and an organic compound containing an ester bond in the molecule.

  However, in Patent Document 1, when a special organic compound is added, another problem such as a problem of the outflow of the organic compound and a problem of hydrolysis of the ester bond occurs, and the problem of Patent Document 1 is improved. Regarding the technology, the present applicant obtained a patent as disclosed in Patent Document 2.

  That is, the method for producing a polyethylene terephthalate resin molded article of Patent Document 2 is an injection molded article comprising 100 parts by weight of a polyethylene terephthalate resin and 1 to 100 parts by weight of an inorganic filler having an average particle size of 0.1 to 20 μm or The extruded product is irradiated with far-infrared rays using a far-infrared heater using ceramics having a spectral emissivity of 90% or more as a radiating member measured according to JIS R1801, and the temperature rising rate is 5 to 200. After the heat treatment until the surface temperature of the molded product becomes 110 to 240 ° C. at a temperature of 100 ° C./minute, the molded product is cooled at a cooling rate of 1 to 50 ° C./minute until the surface temperature becomes 60 ° C. is there.

  The effect of Patent Document 2 is a polyethylene terephthalate system which is excellent in heat resistance and can be used as tableware even when subjected to boiling washing, hot air drying, sterilization treatment or heat treatment in a microwave oven. The resin molded product can be reliably obtained by a simple operation such as irradiation of far infrared rays using a far infrared heater.

  However, in Patent Document 1, the method of cooling the polyethylene terephthalate resin released from the mold, that is, the molded polyethylene terephthalate resin after heat treatment promotes the crystallization of polyethylene terephthalate, but the surface of the terephthalate is increased by the crystallization process. Further, there is a problem in that the luster is lost, and deformation defects may occur after being removed from the mold, and further, the number of processes is increased and the cost is increased.

Japanese Patent Laid-Open No. 10-292097 Japanese Patent No. 4318570

  The problem to be solved by the present invention is that, in the method of Patent Document 2, the gloss of the surface is lost by the crystallization process, and deformation defects may occur after being removed from the mold. There was a problem of inviting up. That is, the surface in the crystallization process loses its gloss and the number of processes increases, resulting in an increase in cost.

In order to solve the above problems, the highly crystallized polyethylene terephthalate composition of the present invention is formed by injection molding with a mold in which a kneaded material containing the following component A and component B and component C or component D is heated to 110 to 180 ° C. The main characteristics were obtained.
Component A: Thermoplastic resin containing 50 to 95% polyethylene terephthalate Component B: Inorganic filler containing 5 to 70% with respect to polyethylene terephthalate Component C: Weight reduction rate by thermogravimetry at 250 ° C. is less than 10% and Metal soap having an alkyl group structure having 14 or more continuous carbon bonds and 1 to 3% of the weight of Component A Component D: Weight reduction rate by thermogravimetry at 250 ° C. is less than 10% and continuous Fatty acid ester having an alkyl group structure having 14 or more carbon bonds and 1 to 10% of the weight of Component A.

  The present invention has good moldability, gloss on the surface, and good heat resistance.

FIG. 1 is a table showing the results of the method of the present invention in an experiment conducted to confirm the effect. FIG. 2 is a table showing the results of a comparative example that deviates from the conditions of the method of the present invention in an experiment conducted to confirm the effect.

(Component A)
Component A is polyethylene terephthalate and is a resin having an intrinsic viscosity of 0.40 to 0.80, preferably 0.50 to 0.70. Polyethylene terephthalate can be freely selected without designation of virgin material, recycled material, and the like.

  The component content of polyethylene terephthalate is 50 to 95%, more preferably 65 to 85%. Moreover, a thermoplastic resin can be arbitrarily added according to various purposes within a range not impairing the effects of the present invention.

  Specifically, the thermoplastic resin to be added is acrylonitrile butadiene styrene copolymer or acrylic resin for improving paintability, polyester elastomer, polyurethane elastomer, styrene copolymer for adding impact resistance, etc. There is.

  In addition, light stabilizers, ultraviolet absorbers, neutralizers, lubricants, antifogging agents, antiblocking agents, coloring materials, antistatic agents, and flame retardants can be optionally added as long as the effects of the present invention are not impaired. .

(Component B)
Component B is an inorganic filler, and talc is most desirable. In addition, glass fiber, calcium carbonate, clay, mica, and the like can be selected. The component content is 5 to 70%, more preferably 10 to 35% with respect to Component A.

(Component C)
Component C is a metal soap having an alkyl chain with 14 or more carbon linkages, even if the weight loss up to 250 ° C. in pyrolysis gravimetry is less than 10%. For example, calcium myristate, calcium stearate, calcium oleate and the like can be used.

(Component D)
Component D selects a fatty acid ester whose weight loss to 250 ° C. in pyrolysis gravimetry is less than 10% and whose alkyl chain has 14 or more carbon linkages. For example, fatty acid esters such as glycerol mono-distearate, glycerol mono-dibehenate, and propylene glycol monostearate can be used.

(Molding method)
“1”: The composition of the present invention is melt-kneaded by putting it into a melt-kneading apparatus capable of uniformly mixing a pulverized molded product, a pellet-like component A, a powder-like component B, and a component C. Can be obtained.

  “2”: The heating temperature at the time of melt kneading is a temperature that becomes 220 to 330 ° C. in consideration of the melting point of polyethylene terephthalate from the viewpoint of achieving uniform mixing while melting component A and suppressing volatilization of component C. Is preferable, 250 to 280 ° C. is more preferable, and it is more preferable to use an apparatus for performing vacuum deaeration.

  The rotational speed at the time of melt kneading may be set in an appropriate range according to the mixing equipment from the viewpoint of uniform mixing. For example, in an extruder, 50 to 300 rotations are preferable. The present invention may be produced from a melt-kneaded intermediate material in which polyethylene terephthalate, endless filler, and powdered antioxidant are put into a kneading apparatus.

  “3”: Examples of the uniform melt kneader include a single screw extruder, a twin screw extruder, a kneader, and a Banbury mixer. Among them, it is preferable to use a twin screw extruder that can vacuum deaerate the inside of the cylinder during melt kneading. The order in which the materials are charged is not particularly limited, but it is desirable to melt and knead a mixture obtained by uniformly mixing Component A, Component B, Component C or Component D.

“4”: For component A, component B, component C, and component D, the parts by mass shown in the figure were blended.
“5”: Component A, Component B, Component C or Component D was hand blended at room temperature. This mixture was put into a twin screw extruder PCM30 (manufactured by Ikegai Co., Ltd.) and melt kneaded at a temperature setting of 240 to 270 ° C. and a rotation speed of 150 rpm to obtain a product.

(Molded body)
“6”: Since component A has a property of absorbing moisture, it is preferable that the product obtained by the above melt-kneading is dried at 130 ° C. for 4 hours or more before molding and molded with a water content of 300 ppm or less. In a state containing moisture, hydrolysis of component A is promoted, and the mold release property is deteriorated, the molded product surface is abnormal, and the moldability is likely to be nonuniform.

  “7”: The temperature of the injection molding machine (SE100S manufactured by Sumitomo Heavy Industries, Ltd.) is not particularly specified as long as the composition is sufficiently melted and fluidized, and is generally 250 to 280 ° C.

  “8”: The mold temperature during injection molding is 110 to 180 ° C., preferably 130 to 150 ° C. The heat medium can be appropriately selected from water vapor, machine oil, thermocouple, and the like. When the mold temperature is 90 ° C. or lower, it is difficult to produce crystals, and in the region below 90 to 110 ° C., the crystal distribution of the molded product becomes non-uniform, resulting in deterioration of heat resistance and surface properties.

  Although the temperature setting of 180 ° C. or higher is not possible with the current equipment, the expected result is that component C is highly volatilized and the additive adheres to the mold, adheres to the molded body, and the mold separation becomes worse. It can be considered that the molding cycle becomes longer.

  “9”: The temperature of the injection molding machine is not particularly specified as long as the composition is sufficiently melted and fluidized, and is generally 250 to 280 ° C.

“10”: In the present invention, more specifically, the numerical value obtained by the calculation formula for the molded product after mold release may be 25 to 45.
(ΔHm−ΔHc) / (complete heat of fusion of PET × weight ratio of PET in the mixture)
PET: Polyethylene terephthalate
ΔHm (mJ / mg): melting enthalpy
ΔHc (mJ / mg): Crystal formation enthalpy

  “11”: When the numerical value obtained by the above formula is lower than 25, there are many amorphous parts of polyethylene terephthalate, which is a cause of heat-resistant deformation, the luster disappears by post-heating, and uneven shrinkage occurs. Deformation may occur due to heating by. Making it higher than 50 is difficult from the viewpoint of mass production technology and composition.

  “12”: Further, in the above, the present invention cools the molded product after mold release, and this cooling time is about 10 to 100 seconds, preferably 30 to 50 seconds, depending on the mold temperature. If it is shorter than 10 seconds, the mold holding is poorly deformed, and crystallization is not sufficiently progressed. If it is longer than 100 seconds, the molding efficiency deteriorates.

Hereinafter, the results of experiments conducted to confirm the effects of the present invention will be described.
The composition of the molded product of the present invention and the molded product of the comparative example are as shown in FIGS. Items outside the scope of the present invention are shaded.
In Table 1, the components A to D described in FIG. 1 and FIG.
Table 2 shows the evaluation criteria for the experiment.

It supplements about the evaluation criteria of Table 2.
(Evaluation criteria)
(Releasability / surface irregularities)
When releasing the mold after injection molding, the molded product will not be deformed or taken out. It was set as “x”.

(Surface gloss)
Glossy and glossy items were marked with “◯”, and those without glossy were marked with “x”.

(Load deflection temperature)
JIS K7191 and a load of 1.8 MPa were adopted. Since it is often used as a food container, a product having a temperature of 90 ° C. or higher was considered good.

(Impact strength)
The Charpy impact strength was adopted, and the edgewise method notch of JIS K7111 was adopted. A tableware container having an impact strength of 5 KJ / m ² or more was considered good in order to suppress breakage when dropped.

(Bending strength)
The bending strength during actual use was 50 MPa or more.

(Crystallinity)
It was selected as the measurement location in the center of the molded product. Differential scanning calorimetry was performed using EXTAR6000 (manufactured by SII Nanotechnology Co., Ltd.) under the conditions of a temperature increase of 10 ° C./min and a sample amount of 6 to 10 mg. / Mg), and 25 or more were considered good.

  As shown in FIG. 1, Examples 1 to 9 satisfying the present invention were good in all evaluations. Therefore, it has been found that the present invention can obtain a highly crystallized polyethylene terephthalate composition which is not easily thermally deformed, has excellent impact resistance, and is glossy.

Claims (2)

A highly crystallized polyethylene terephthalate composition obtained by injection molding a kneaded material containing the following component A and component B and component C or component D with a mold heated to 110 to 180 ° C.
Component A: Thermoplastic resin containing 50 to 95% polyethylene terephthalate Component B: Inorganic filler containing 5 to 70% with respect to polyethylene terephthalate Component C: Weight reduction rate by thermogravimetry at 250 ° C. is less than 10% and Metal soap having an alkyl group structure having 14 or more continuous carbon bonds and 1 to 3% of the weight of Component A Component D: Weight reduction rate by thermogravimetry at 250 ° C. is less than 10% and continuous Fatty acid ester having an alkyl group structure having 14 or more carbon bonds and 1 to 10% of the weight of Component A. 2. The highly crystallized polyethylene terephthalate composition according to claim 1, wherein a numerical value obtained by the following formula is 25 to 50.
(ΔHm−ΔHc) / (complete heat of fusion of PET × weight ratio of PET in the mixture)
PET: Polyethylene terephthalate
ΔHm (mJ / mg): melting enthalpy
ΔHc (mJ / mg): Crystal formation enthalpy

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