JPS6360789B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a polyester composition suitable as a molding material with improved crystallinity. More specifically, the present invention relates to a novel polyester composition that exhibits excellent moldability at low mold temperatures and provides molded articles with excellent physical properties. Polyethylene terephthalate has excellent mechanical properties, chemical resistance, and heat resistance, and is used in many products as fibers and films. However, when used as an injection molded product for plastic purposes, there are many restrictions in the molding process due to the unique crystallization behavior of polyethylene terephthalate. Therefore, despite its other excellent properties, its use is extremely limited. That is, although polyethylene terephthalate is essentially a crystalline polymer, the crystallization rate at low temperatures is slow, so it is necessary to maintain the mold temperature at 160°C or higher. Such a high mold temperature not only significantly lengthens the molding cycle but also causes operational problems, which is unfavorable in terms of productivity. Furthermore, if the mold temperature is set to a low temperature around 100°C, crystallization will hardly progress. For this,
The molded product has poor release from the mold cavity, and the obtained molded product has extremely poor shape stability.Furthermore, the molded product has extremely poor surface gloss due to the appearance of avatar-like patterns on the surface of the molded product. The disadvantage is that it cannot be obtained. Various methods have been proposed in the past to improve these drawbacks. For example, Japanese Patent Publication No. 44-7542 discloses a method of increasing the crystallization rate by incorporating about 0.2 to 2% by weight of a crystal nucleating agent made of inorganic solid particles, of which talc is a typical example. There is. Further, JP-A-48-4097 discloses a method of blending an alkali metal salt of an organic carboxylic acid. However, in any of these methods, the crystal nucleating agent added is 200%
Although it has the effect of accelerating the crystallization rate near high temperatures around °C, this effect is hardly recognized in the low temperature range. As a result, the mold temperature when molding these compositions remains
A high temperature setting of 140℃ or higher is required. Furthermore, Japanese Patent Publication No. 55-47058 discloses a composition in which polyethylene terephthalate is blended with glass fiber, an ionomer, neopentyl glycol dibenzoate, and the like. Such a compounding composition promotes the crystallization of polyethylene terephthalate at low temperatures, but when a molding material made of this composition is subjected to injection molding, mold deposits are observed to occur in the mold cavity, and melting occurs. If the temperature exceeds 275℃, resin burn will occur. Furthermore, when drying the molding material with a normal hopper dryer, the components in the composition evaporate when dried at the normal drying temperature of polyethylene terephthalate (110 to 150°C). The current situation is that further improvements are desired from this perspective. The present inventors have conducted intensive research to solve the above-mentioned drawbacks of polyethylene terephthalate, and as a result, have arrived at the composition of the present invention. That is, the polyester composition according to the present invention is
(A) Polyethylene terephthalate with an intrinsic viscosity of 0.4 or more, (B) Crystal nucleating agent 0.2 to 5% by weight (based on the total composition weight), (C) (a) The number of carbon atoms forming the ring skeleton is 9 to
25, (b) two or more aromatic hydrocarbon rings are bonded together and the number of carbon atoms is 12 to 25;
25, and (c) one or two hydrocarbon polycyclic compounds having 13 to 25 carbon atoms in which two or more aromatic hydrocarbon rings are bonded to hydrocarbon groups. More than one hydrocarbon polycyclic compound 1 to 10
% by weight (relative to the total composition weight). The polyethylene terephthalate used as component (A) in the present invention is a polyester containing at least 80 mol% or more, preferably 90 mol% or more of ethylene terephthalate repeating units,
An acid component and a glycol component may be copolymerized within a range that does not impair crystallinity. The viscosity is preferably 0.4 or more, more preferably 0.5 or more. The above-mentioned polyester can be produced by a conventional production method, such as a melt polycondensation reaction or a method combining this with a solid phase polymerization reaction. The blending amount of polyethylene terephthalate is 85 to 85% of the total composition weight if the reinforcing material described below is not present.
It is 98.8% by weight. The crystal nucleating agent used as component (B) in the present invention includes inorganic solids such as talc, kaolin, mica, antimony trioxide, calcium carbonate, etc., sodium acetate, sodium stearate, lithium terephthalate, and benzoic acid. Alkali metal salts of monocarboxylic acids or dicarboxylic acids such as sodium chloride, sodium benzenesulfonate, general formula

[expression] or

[Formula] (In the above formula, M and M' are the same or different alkali metals, and n and m are 1 or 2), For example, disodium p-phenolsulfonate, 2naphthol-6-sulfonic acid These include alkali metal salts of sulfonic acids such as disodium. A preferred component (B) is disodium p-phenolsulfonate. More preferably, it is polyethylene terephthalate in which disodium p-phenolsulfonate is blended during any of the transesterification reaction, esterification reaction, or polycondensation reaction in the manufacturing process of polyethylene terephthalate. Even if these components are added after the completion of polycondensation, the effect will be small. This is because even if disodium p-phenolsulfonate is added after the completion of polycondensation, the crystallization rate will not be much higher than when added before the completion of polycondensation. The blending amount of these compounds is preferably 0.5 to 5% by weight based on the weight of the resin composition. If this amount is too small, the crystallization rate will not be sufficiently high.
Furthermore, even if the amount is too large, the increase in crystallization rate will almost reach saturation, so there is no advantage. The hydrocarbon polycyclic compound used as component (C) is a crystal nucleating agent that promotes the crystallization of polyethylene terephthalate blended by any of the above methods over a wide temperature range, and especially at low temperatures. have a function. These (C) components are thought to have the effect of facilitating the molecular movement of polyethylene terephthalate, but their true nature is not necessarily clear. In any case, by blending these (C) components, a composition that can be molded even at a low mold temperature of around 100°C can be obtained, so these (C) components have a crystallization promoting effect even at low temperatures. It also shows that. The present inventors searched for compounds exhibiting the above-mentioned crystallization promoting effect from among a vast number of compounds, and as a result, they discovered that hydrocarbon polycyclic compounds exhibit an excellent promoting effect. These compounds do not have ketone groups or ester groups like benzophenone and neopentyl glycol, which are generally known as accelerators, and have poor affinity with water, so even if they are added to polyester, they cannot be hydrolyzed. Does not cause viscosity reduction.
Furthermore, since it is a polycyclic structure, it has a boiling point higher than the melting point of polyester, and does not volatilize during blending or drying of the resin. Furthermore, although this compound is composed only of hydrocarbon groups, it has been found that it has many advantages such as extremely good compatibility with polyester and does not cause mold deposits during molding. Examples of hydrocarbon polycyclic compounds used as component (C) in the present invention include (a) azulene, acenaphthene, fluorene, phenanthrene, aceanthrene, pyrene, triphenylene, etc. having 9 to 25 carbon atoms forming a ring skeleton; A certain hydrocarbon polycyclic compound, (b)
Fluoranthene, 1-1′ binaphthyl, 1-2′ binaphthyl, 2-2′ binaphthyl, o-terphenyl,
Hydrocarbon polycyclic compounds having 12 to 25 carbon atoms, in which two or more aromatic hydrocarbon rings such as m-terphenyl and p-terphenyl are bonded by bonds, and (C)
2 such as trans-stilbene, triphenylethane, etc.
It is a hydrocarbon polycyclic compound having 13 to 25 carbon atoms, in which more than one aromatic hydrocarbon ring is bonded with a hydrocarbon group. Further, these compounds may have a hydrogen atom, an alkyl group, or an allyl group. When used, one selected from the above compounds may be used.
It may be a species or a mixture of two or more species. Among these, particularly preferred examples are phenanthrene, m-terphenyl, and triphenylethane. The amount of the above component (C) is 1% based on the total weight of the composition.
-10% by weight, preferably 2-8% by weight. If the amount is less than 1%, it will not be possible to obtain a molded product with sufficient crystallinity at a mold temperature of 110°C, and if it exceeds 10% by weight, mold deposits will occur, which is unfavorable for molding. . In addition to the above-mentioned components, the composition of the present invention may contain a reinforcing agent. Examples of such reinforcing materials include fibrous inorganic substances such as glass fibers, carbon fibers, and asbestos fibers. When these reinforcing agents are used in combination with components (B) and (C), they have the effect of imparting shape stability to the molded product made from the composition of the present invention, and at the same time improve heat resistance and mechanical properties. It also has the effect of improving A particularly preferred example of these reinforcing materials is glass fiber. The amount of these reinforcing agents is generally 10 to 60% by weight, preferably 15 to 55% by weight, based on the total weight of the composition. If the amount is less than 10% by weight, the provision of shape stability is insufficient, and if it exceeds 60% by weight, the molded product becomes brittle and its practical value decreases. In addition, when blending the reinforcing material, the blending amount of polyethylene terephthalate is 25 to 88.8% by weight. As mentioned above, the polyester composition of the present invention differs from conventional polyester compositions in that it has improved moldability at low temperatures. in this way,
The objects of the present invention can be further improved by combining the components (B) and (C) with the properties and blending amount of the reinforcing material. The composition of the present invention can be manufactured by any commonly used method. For example, after blending polyethylene terephthalate, component (B), and reinforcing material using an extruder, component (C) may be dry blended during molding, or all components may be blended using an extruder. The composition of the present invention may contain various commonly used additives depending on the purpose of use, such as oxidation stabilizers, ultraviolet absorbers, lubricants, mold release agents, flame retardants,
Antistatic agents, colorants, etc. may be added. The polyester composition of the present invention obtained in this manner exhibits excellent moldability and shape stability when molded not only in high-temperature molds but also in low-temperature molds around 100°C. gives a good molded product. In this way, it enables molding in low temperature ranges that were impossible with conventional polyethylene terephthalate, and together with its original mechanical properties, heat resistance, and chemical resistance, it expands the field of polyethylene terephthalate as an industrial resin. The significance of this is great. The present invention will be explained below with reference to examples, but it goes without saying that the technical scope of the present invention is not limited to these examples. In the examples, "parts" and "%" indicate "parts by weight" and "% by weight." Example 1 Polyethylene terephthalate 100 with intrinsic viscosity 0.7
In the part, talc ("MS type" Nippon Talc Co., Ltd.)
and a glass tip strand ("MA429S", manufactured by Asahi Fiberglass Co., Ltd.) with a length of 3 mm, and phenanthrene were weighed in the proportions shown in Table 1 and then mixed in a rotating drum blender. Next, this was put into the hopper of a 70 mmφ vent type extruder, and after melting and mixing at a barrel temperature of 260-280-280°C, it was made into pellets. After drying the obtained pellets under reduced pressure at 140℃ for 5 hours, using a KC-20/Kawaguchi Tekko Co., Ltd. injection molding machine, the barrel temperature was 270-280-280℃.
ASTM No. 1 dumbbell test pieces were molded at an injection pressure of 300 to 500 Kg/cm ² , a molding cycle of 25 seconds, and a mold temperature of 100 to 160°C. The mold deposit and mold releasability were determined by observing the mold surface after 30 consecutive shots, and the mold releasability was expressed as the drop rate due to protrusion from the mold. The surface gloss was measured at an angle of 60° based on ASTM D528 using the obtained dumbbell test piece. The heat shrinkage rate was calculated from the following formula, where L ₀ is the width of the molded dumbbell test piece, and L ₁ is the width after heat treatment at 120° C. for 15 hours in a gear oven. Heating shrinkage rate (%)=L ₀ −L ₁ /L ₀ ×100 The obtained results are shown in Table 1 as Invention Examples 1 to 5 along with Comparative Examples 1 to 4. Example 2 200 parts of dimethyl terephthalate, 142 parts of ethylene glycol, 4 parts of disodium p-phenolsulfonate (or disodium 2-naphthol-6-sulfonate), 0.1 part of manganese acetate, and 0.1 part of antimony trioxide were placed in a reactor. Prepared under nitrogen stream at 190℃
The transesterification reaction was carried out at ℃ for 3 hours to distill off most of the methanol, and then the temperature was raised to 260℃ and the pressure was reduced.
The polycondensation reaction was carried out at 280° C. for 3 hours under a vacuum of 0.5 mmHg. The obtained polymer is white and has a melting point of 250-255.
°C, and the intrinsic viscosity was 0.6. Using the obtained polyethylene terephthalate, a resin composition was produced in the same manner as in Example 1, and its moldability was evaluated. The results are shown in Invention Examples 6 to 9 in Table 1.

【table】

[Table] Example 3 A resin composition was produced in the same manner as in Example 1 using the polyethylene terephthalate obtained in Example 2 and the various (C) components and reinforcing materials shown in Table 2.
The moldability was evaluated. The results are shown in Invention Examples 10 to 12 in Table 2.

【table】

Claims (1)

[Scope of Claims] 1 (A) polyethylene terephthalate having an intrinsic viscosity of 0.4 or more, (B) a crystal nucleating agent of 0.2 to 5% by weight, (C) (a) the number of carbon atoms forming the ring skeleton is 9 to 25. (b) A hydrocarbon polycyclic compound having 12 to 25 carbon atoms, in which two or more aromatic hydrocarbon rings are bonded together, and (c) Two or more aromatic hydrocarbons. Consisting essentially of 1 to 10% by weight of one or more hydrocarbon polycyclic compounds selected from hydrocarbon polycyclic compounds having 13 to 25 carbon atoms in which hydrogen rings are bonded with hydrocarbon groups. Polyester composition. 2. Component (B) is selected from compounds represented by the general formulas [Formula] and [Formula] (in the above formula, M and M' are the same or different alkali metals, and n and m are 1 or 2). The polyester composition according to claim 1, which is at least one compound.