JPH05293878A - Manufacture of heat-resistant resin container - Google Patents

Abstract

PURPOSE:To provide the manufacturing method for a heat-resistant container easily and efficiently in a short time regardless of its wall thickness by blow molding. CONSTITUTION:A molded product is obtained by infection molding using 100 pts.wt. of a resin composition that is composed of 1-100 pts.wt. of at least one kind at least one kind of polybutylene terephthal resin and 99-0 pts.wt. of at least one kind of polyethylene terephthalate resin at the temperature of its melting point or above. Said molded product is cooled down to the temperature lower than the crystallizing temperature and higher than its glass transition point, and it is blow molded in a mold, the temperature of which is adjusted to the temperature higher than its cooling crystallizing temperature and lower than the melting point of resin which is the lowest of all melting points of resins to be used for the purpose.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a heat-resistant resin container, and more particularly to a method for producing a transparent, heat-resistant, hot-fillable heat-resistant resin container by blow molding.

[0002]

2. Description of the Related Art As a conventional container made by blow molding capable of hot filling, polyethylene terephthalate (hereinafter abbreviated as PET) resin is stretch blow molded,
It is known that it is manufactured by heat fixing in a mold,
Since this product has insufficient heat resistance, only a die part to which the most heat is applied is made of a PET resin having a high crystallization temperature, or a laminated structure of polyarylate (hereinafter abbreviated as PAR) resin is used. It has been adopted, but this still has problems with hot fill at temperatures near 100 ° C.

As this heat-resistant resin container, those made of polycarbonate resin, polymethylpentene resin, etc. are also known, but these are gas barriers.
It has the disadvantage that it is unsuitable as a container for bottles due to its poor property, and it is disadvantageous in that it cannot be used as a one-way bottle because the one using the PAR resin is too expensive.

[0004]

Therefore, the present inventors have found that polybutylene terephthalate (hereinafter referred to as PBT) has good gas barrier properties and excellent heat resistance, and is relatively inexpensive as compared with other engineering plastics. A method for producing a transparent and heat-resistant container by blow molding using a composition comprising a resin and a PET resin (see JP-A-4-63836) has been proposed. In this manufacturing method, it takes too much molding time to cool the composition below the glass transition point of the parison and then reheat it, and when the parison is thick, crystallization of the composition occurs due to temperature unevenness in the thickness direction during reheating. It has been found that there is a drawback that the blow molding becomes defective because the heating surface and the non-heating surface have different degrees.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a method for producing a heat-resistant resin container which has solved the above disadvantages and drawbacks, and it relates to at least one PBT resin 1 to
100 parts by weight of a resin composition consisting of 100 parts by weight and at least one kind of PET resin 99 to 0 parts by weight is injection-molded at a temperature above its melting point to form a molded product, and this molded product is crystallized from the composition. Below the crystallization temperature and above the glass transition temperature, and then in a mold that has been heated to a temperature above the cold crystallization temperature and below the melting point of the lowest melting point resin used. It is characterized by blow molding.

That is, the present inventors can manufacture a heat-resistant resin container which can shorten the molding time of the injection blow molding and can stably perform the blow molding even if the parison is thick. As a result of various studies to develop a method, PBT resin 1 to 100 parts by weight and PET resin 99
In a manufacturing method for manufacturing a heat-resistant resin container by blow molding from a composition comprising 0 to 0 parts by weight, the cooling temperature for cooling the parison obtained by injection molding is lower than the crystallization temperature of the composition. If so, it is found that reheating is not necessary, and it is possible to obtain a transparent and heat-resistant container in a short time even when the parison is thick, and it is possible to obtain a transparent and heat-resistant container in the subsequent blow molding. The present invention has been completed by confirming that it is necessary to adjust the temperature to a temperature higher than the cold crystallization temperature and lower than the melting point of the resin having the lowest melting point among the resins used. This will be described in more detail below.

[0007]

The present invention relates to a method for producing a heat-resistant container, in which 100 parts by weight of a resin composition consisting of 1 to 100 parts by weight of a PBT resin and 99 to 0 parts by weight of a PET resin are heated to a temperature above its melting point. Injection-molding to make a molded product, and cooling this molded product to a temperature lower than the crystallization temperature of the composition and higher than its glass transition point, and then its cold crystallization temperature (crystals when heated from the low temperature side Aging temperature: "Saturated Polyester Resin Handbook" published by Nikkan Kogyo Shimbun, Kazuo Yuki 20
(See page 285) above, and in a mold heat-adjusted to a temperature lower than the melting point of the resin with the lowest melting point (endothermic peak due to melting by differential scanning calorimeter: ibid., Page 285 above) among the resins used. It is characterized by being molded into a container, which makes it possible to obtain the desired transparent and heat-resistant container in a shorter time than the conventional method and regardless of the thickness of the parison. The advantage is given.

Since the heat-resistant resin container according to the present invention has excellent heat resistance, the PBT resin 1
It is said that the resin is made from a composition comprising 100 to 100 parts by weight of PET resin and 99 to 0 parts by weight of PET resin. This resin has the same weight as the polyvalent carboxylic acid and the polyvalent alcohol shown in Table 1. It may be a united body. Further, the PBT-based resin and the PET-based resin may be those to which a surface active agent such as an antistatic agent and an antifogging agent, a filler and the like are added if necessary. The heat-resistant resin container according to the present invention is made of polyvinylidene chloride, ethylene-
A barrier layer made of vinyl alcohol copolymer, nylon (trade name) resin or the like may be further provided.

[0009]

[Table 1]

The method for producing a heat-resistant container according to the present invention is a molded article (parison) obtained by injection molding from the above composition.
In the method previously proposed by the present inventors (JP-A-4-63836), the parison is completely cooled and solidified to a temperature below the glass transition point to crystallize the composition. It is re-heated after being made into a low temperature state and is blow-molded in a mold with a limited temperature, which takes too much molding time, and if the parison is thick, defective products will be generated by blow molding. Therefore, in the present invention, a method of not completely cooling and solidifying at the time of forming the parison, and cooling this to a temperature lower than the crystallization temperature and higher than the glass transition point is used.

According to this, since the composition is not rapidly crystallized and is in a low crystallization state, the next blow molding can be carried out without reheating. The disadvantage of taking too much molding time is eliminated, and this also eliminates the occurrence of a large temperature gradient in the thickness direction of the parison due to rapid heating during reheating and the occurrence of crystallinity exposure. -The advantage that the exposure of the thickness of the product during molding and the exposure of transparency can be prevented is given.

The parison cooled to the above conditions is molded into a desired container by blow molding in the next step. If the temperature of the mold is lower than the cold crystallization temperature, the composition is Since it does not crystallize, heat resistance is not imparted to the container, so it is required to be above the cold crystallization temperature, which is also above the melting point of the lowest melting point resin used. At a high temperature, the composition melts in the mold and a container is not formed. Therefore, it is necessary to adjust the temperature by heating to a temperature lower than the melting point of the resin having the lowest melting point among the resins used.

[0013]

EXAMPLES Next, examples, comparative examples and reference examples of the present invention will be given. Examples, Comparative Examples, Reference Examples PBT resin / FP-600 [Product name of Polyplastics Co., Ltd.]
A glass transition temperature of 58 ° C, a crystallization temperature of 174 ° C, a cold crystallization temperature of 97 ° C, and a maximum melting point of 40 parts by weight and 60 parts by weight of PET resin / SSF-30M [trade name of Kanebo Co., Ltd.]. The resin composition having a low melting point of 220 ° C. was pelletized using a twin-screw extruder rotating in the same direction.

An injection molding machine, ASB-50 (trade name, manufactured by NISSEI S-B Machine Co., Ltd.) having a blow molding function integrated with the pellets, has a diameter of 29 mmφ and a height of 29 mmφ.
Two kinds of parisons having a thickness of 100 mm, a thickness of 1.8 mm and a thickness of 2.7 mm were prepared, cooled to the temperature shown in Table 2 (reheated if necessary), and then heated to the temperature shown in Table 2. Using a mold, blow mold at the temperature shown in Table 2 to make a container with a diameter of 50 mmφ and a length of 155 mm, and the transparency, heat resistance, product thickness unevenness and blow molding of the obtained container are performed. When the results of yes and no were examined, the results shown in Table 2 were obtained.

[0015]

[Table 2]

That is, according to this, by blow-molding a composition comprising a PBT resin and a PET resin according to the present invention by the method of the present invention, a container can be molded regardless of the thickness of the parison, In this case, it was confirmed that reheating is not necessary, so that the molding time can be shortened and the processing loss can be reduced.

[0017]

The present invention relates to a method for manufacturing a heat-resistant container, which is, as described above, a PBT resin 1-10.
100 parts by weight of a resin composition consisting of 0 parts by weight of PET resin and 99 to 0 parts by weight of PET resin are injection-molded at a temperature equal to or higher than the melting point to prepare a molded product, which is lower than the crystallization temperature of the composition, It is cooled to a temperature higher than its glass transition point, and then blow-molded into a container in a mold adjusted to have a temperature higher than its cold crystallization temperature and lower than the melting point of the resin having the lowest melting point among the resins used. According to this, since it is possible to perform blow molding of the cooled molded body without reheating, the molding time can be shortened as compared with the conventional method. In this case, since the container can be molded regardless of the wall thickness of the molded body, there is an advantage that the desired heat-resistant container can be manufactured easily and efficiently.

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Claims (1)

[Claims] 1. A resin composition comprising 100 parts by weight of 1 to 100 parts by weight of at least one polybutylene terephthalate resin and 99 to 0 parts by weight of at least one polyethylene terephthalate resin. Injection molding is performed at a temperature above the melting point to make a molded article, the molded article is cooled to a temperature lower than the crystallization temperature of the composition and higher than its glass transition point, and then at or above its cold crystallization temperature, and Of the resins having the lowest melting point, the method for producing a heat-resistant resin container is characterized by performing blow molding in a mold whose temperature is adjusted to a temperature lower than the melting point of the resin having the lowest melting point.