JP2636993B2 - Method for manufacturing transparent heat-resistant injection molded products - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a transparent heat-resistant injection-molded article, particularly a transparent heat-resistant plastic container used for microwave ovens, a transparent heat-resistant container capable of heat sterilization and hot filling, and a switch button. More particularly, the present invention relates to a method for producing electric parts, automobile parts, etc., which require high transparency.

[0002]

2. Description of the Related Art Polybutylene terephthalate (hereinafter referred to as PB)
Resins are abundant in heat resistance, abrasion resistance, and weather resistance and are relatively inexpensive as engineering plastics. Although it is used, it has recently come to be used for food packaging for microwave ovens because of its good heat resistance.

[0003]

However, molded articles obtained by injection-molding this PBT resin have the disadvantage that the crystallization speed of the PBT resin is so high that all molded articles become opaque. For example, switch buttons and the like obtained by injection molding of this PBT resin are required to transmit light to some extent, and thus may be required to be transparent. Since a microwave oven container is opaque, its contents cannot be seen. Is required to obtain a transparent molded product. In addition to these uses, providing transparency to PBT resin injection molded products having well-balanced physical properties is important in expanding its use. This transparency is strongly desired because it is advantageous.

[0004]

SUMMARY OF THE INVENTION The present invention relates to a method for producing a transparent heat-resistant molded article which solves the above problems, and which comprises at least one kind of PBT resin 40 to 10.
A resin composition comprising 0 parts by weight and 60 to 0 parts by weight (preferably 60 to 10 parts by weight) of at least one kind of crystalline polyethylene terephthalate (hereinafter abbreviated as PET) resin (however, 100 parts by weight of a PBT homopolymer) Parts), and quenched or slowly cooled in a molding die, or a weight of at least one PBT resin of less than 10 to 40 parts by weight and at least one crystalline PET resin of more than 90 to 60 parts by weight. Injection molding of the resin composition consisting of parts and annealing in a molding die, annealing after cooling in a molding die, or at least one type of PBT-based resin
100 parts by weight and at least one amorphous PET-based resin 4
A resin composition comprising 0 to 0 parts by weight (excluding 100 parts by weight of a PBT homopolymer) is injection-molded and quenched or gradually cooled in a molding die, or at least one type of PBT.
The resin composition comprising 10 to less than 60 parts by weight of the base resin and 90 to 40 parts by weight of at least one amorphous PET-based resin was gradually cooled in the molding die or quenched in the molding die. After the post-annealing, characterized in that it is heated in a mold that is heated and adjusted to a temperature lower than the melting point of the resin having a lower melting point among the resins used at a temperature higher than the cold crystallization temperature of the resin composition. Is what you do.

That is, the present inventors have studied various methods for producing a molded article having excellent transparency and excellent heat resistance by injection molding. In particular, the mixing ratio, the cooling method in a molding die, and the like have been studied. As a result of specifically examining the relationship between the necessity of annealing, a resin composition comprising 40 to 100 parts by weight of at least one kind of PBT resin and 60 to 0 parts by weight of at least one kind of crystalline PET resin (however, P
In the case of BT homopolymer (excluding 100 parts by weight), the molded article in the molding die is cooled rapidly or gradually, and at least one type of PBT resin is less than 10 to 40 parts by weight and at least one type of PBT resin. In the case of a resin composition comprising a crystalline PET resin in an amount of more than 90 to 60 parts by weight, the molded article in the molding die is gradually cooled or rapidly cooled and then annealed. A resin composition comprising 60 to 100 parts by weight of a PBT-based resin and 40 to 0 parts by weight of at least one kind of amorphous PET-based resin (however, a PBT homopolymer 100
In the case of (excluding parts by weight), the cooling of the molded article in the molding die is performed by quenching or gradual cooling, and at least one type of PBT resin is less than 10 to 60 parts by weight and at least one type of PET resin 90 to 90 parts by weight. In the case of a resin composition consisting of more than 40 parts by weight, the cooling in the molding die is gradually cooled or after quenching, annealing is performed, and then the molded product is heated with a heating die. The inventors have found that a transparent molded article having good heat resistance can be obtained from the composition, and have studied the cooling method, the annealing method, and the heating method using the molding die to complete the present invention. Here, the cold crystallization temperature refers to the temperature at which the crystalline resin starts to crystallize as shown in the DSC curve, and the transparency is defined by JIS K7105.
Based on the haze measured according to the above, the haze of 50% or less was made transparent here. This will be described in more detail below.

[0006]

The PBT resin used in the present invention is a homopolymer or a copolymer thereof, and the PET resin is a homopolymer or a copolymer thereof. The present invention relates to a method for producing a transparent heat-resistant molded article by injection molding of a PBT-based resin composition, which comprises 40 to 100 parts by weight of at least one PBT-based resin and at least one crystalline PET.
60 to 0 parts by weight of the resin (preferably 60 to 10 parts by weight)
And a resin composition consisting of PBT homopolymer 10
0 parts by weight), injection-molded, and quenched or gradually cooled in a molding die, or at least one PBT resin
After injection-molding a resin composition comprising less than 40 parts by weight and at least one kind of crystalline PET-based resin exceeding 90 to 60 parts by weight, and then slowly cooling in a molding die or quenching in a molding die After annealing, or a resin composition comprising 60 to 100 parts by weight of at least one kind of PBT resin and 40 to 0 parts by weight of at least one kind of amorphous PET resin (however, 100 parts by weight of PBT homopolymer) ), Or quenched or slowly cooled in a molding die, or a weight exceeding 10 to less than 60 parts by weight of at least one PBT resin and 90 to 40 parts of at least one amorphous PET resin. After the resin composition consisting of parts is gradually cooled in a molding die or quenched in a molding die and then annealed, then heated and crystallized in a heating die to form a transparent and heat-resistant molded product Need to get It is an.

The resin composition used in the present invention has a total of 100 parts by weight of 40 to 100 parts by weight of at least one PBT resin and 60 to 0 parts by weight of at least one crystalline PET resin. PBT homopolymer 1
00 parts by weight), or at least one PBT
The total of 10 to less than 40 parts by weight of the base resin and at least one of the crystalline PET resins exceeding 90 to 60 is 100 parts by weight, or 60 to 100 parts by weight of at least one PBT resin and at least 1 part by weight. Seed amorphous PET
100 to 100 parts by weight (excluding 100 parts by weight of PBT homopolymer), or 10 to less than 10 to 60 parts by weight of at least one PBT-based resin and at least one kind of amorphous PET resin 90-40
Is more than 100 parts by weight, and more specifically, (a) 40 to 100 parts by weight of one kind of PBT resin and 60 to 0 parts by weight of one kind of crystalline PET resin. Is 100 parts by weight (provided that the PBT homopolymer 100
(B) excluding 0 to 99 parts by weight of one type of PBT resin and 100 to 1 part by weight of one type of PBT resin having a lower crystallization rate than 100 parts by weight. Parts by weight (PB
(C excluding 100 parts by weight of T homopolymer) or (c) at least three types selected from PBT-based resins and crystalline PET-based resins, and as a whole 40 to 100 parts by weight of PBT-based resin and crystalline PET-based resin 60 to 0 (D) from 10 to less than 40 parts by weight of one kind of PBT resin and more than 90 to 60 parts by weight of one kind of crystalline PET resin. (E) three or more types of PBT-based resin and crystalline PET-based resin are selected, and a total of 10 to less than 10 to 40 parts by weight of PBT-based resin and crystalline PET-based resin 90 to 60 are selected. (F) 60 to 100 parts by weight of one kind of PBT-based resin and 40 to 0 parts by weight of one kind of amorphous PET-based resin. Total 100 parts by weight of resin (however, PBT homopolymer 100
(Excluding parts by weight) or (g) a total of 100 to 1 part by weight of one PBT resin having 0 to 99 parts by weight of one PBT resin and 100 to 1 part by weight of one PBT resin having a lower crystallization rate than this; Parts by weight (PB
(Excluding 100 parts by weight of T homopolymer) or (h) at least three types selected from PBT-based resins and PET-based resins, and as a whole 60 to 100 parts by weight of PBT-based resin and 40 to 0 parts by weight of amorphous PET-based resin those resin amount of total consisting of parts consists 100 parts by weight, or (i) one PBT resin 10-6 0 less than parts by weight and parts by weight of more than one kind of amorphous PET resin 90-40 And (j) three or more types of PBT-based resin and amorphous PET-based resin, and 10 to less than 60 parts by weight of PBT-based resin and amorphous PET-based resin as a whole. The total amount of the resin consisting of 90 to 40 parts by weight of the resin is 100 parts by weight, and at least one of them is a crystalline resin.

In the present invention, this resin composition is formed into a molded article by injection molding. As described above, at least one kind of polybutylene terephthalate resin 4 is used.
Inject a resin composition (excluding 100 parts by weight of a PBT homopolymer) comprising 0 to 100 parts by weight and 60 to 0 parts by weight (preferably 60 to 10 parts by weight ) of at least one kind of crystalline PET resin. Molded and quenched or gradually cooled in a molding die, or at least one type of PBT resin 10 to 40
Less than parts by weight and at least one crystalline PET-based resin 90
Injection molding of a resin composition consisting of more than 60 parts by weight, annealing in a molding die or quenching in a molding die followed by annealing, or at least one type of PB
A resin composition (excluding 100 parts by weight of a PBT homopolymer) consisting of 60 to 100 parts by weight of a T-based resin and 40 to 0 parts by weight of at least one kind of amorphous PET-based resin is injection-molded, and a metal mold is formed. The resin composition is quenched or slowly cooled in a mold, or a resin composition comprising 10 to less than 10 parts by weight of at least one PBT resin and 90 to 40 parts by weight of at least one amorphous PET resin. It is annealed after slow cooling in the mold or quenching in the molding die.
The transparent molded product thus produced is then crystallized by heating in a heating mold to obtain the desired transparent heat-resistant molded product.

[0009] When the proportion of the PET resin increases, the resin composition is likely to be whitened by heating in a subsequent heating mold. In this case, the cooling in the molding mold is not rapidly cooled. It is preferable to perform slow cooling or annealing after taking out from the molding die. If the temperature of the cooling mold is lower than the lowest glass transition temperature of the resin used, the effect of the slow cooling cannot be expected, and the annealing temperature is higher than the highest glass transition temperature of the resin used [PBT resin. (Except for the PBT homopolymer), in the case of 100 parts by weight, higher than the lowest cold crystallization temperature], the crystallization proceeds excessively and the molded product is whitened, which is the lowest glass transition among the resins used. Glass transition point [PBT resin (excluding PBT homopolymer) 10
In the case of 0 parts by weight, the temperature must be lower than the lowest cold crystallization temperature].

[0010] In this annealing, if the annealing temperature is lower than the lowest glass transition point of the resin used, there is no annealing effect. Therefore, it is necessary to set the annealing temperature higher than the lowest glass transition point of the resin used. Is the highest glass transition point among the resins using [in the case of 100 parts by weight of PBT resin (excluding PBT homopolymer),
When the temperature is lower than the lowest cold crystallization temperature), the crystallization of the resin composition proceeds rapidly and the sheet becomes opaque, so that it is higher than the lowest glass transition point of the resins used, and the most of the resins used. The temperature must be lower than the high glass transition point (the lowest cold crystallization temperature in the case of 100 parts by weight of a PBT resin (excluding PBT homopolymer)).

[0011] The annealing means that the resin composition is heated to a certain temperature after cooling and then left for a certain period of time, which may be annealed after slow cooling. An annealing process refers to placing a drying furnace, a mold, hot water, etc. on the line of a device that manufactures products and performing annealing.Offline refers to manufacturing a molded product and then leaving it in a dryer or the like at a certain temperature for a certain period of time. It is.

The cooling method using the molding die, the annealing after removal from the die and the transparency after heating in the heating die are as shown in Tables 1 and 2; The difference in the case where PET was used was as shown in Table 3. However, since the PBT resin used in the present invention is for injection molding, it is desirable that the MI value be 30 or more.

[0013]

[Table 1]

[Table 2]

[Table 3]

As described above, the transparent molded article which has been injection-molded, cooled, optionally cooled, and annealed, is then crystallized by heating in a heating mold to obtain the desired transparent heat-resistant molded article. However, this heating mold should be of the same shape as the cooling mold, and its dimensions are the molding shrinkage of the molded article in the cooling mold, and the thermal expansion and shrinkage of the molded article in the heating mold due to crystallization. Furthermore, it may be determined in consideration of the thermal expansion of the heating mold. When the temperature of the heating mold is lower than the cold crystallization temperature of the resin composition, crystallization in the mold becomes difficult to proceed,
If this is set to a temperature higher than the melting point of the resin having a low melting point among the resins constituting the resin composition used here, the molded product will melt, so this is above the cold crystallization temperature of the resin composition, It is necessary to heat and adjust to a temperature lower than the melting point of the resin having the lowest melting point among the resins to be used, whereby a target molded article can be obtained as a transparent and highly heat-resistant one.

[0015]

EXAMPLES Examples of the present invention and comparative examples will now be described.
The evaluation of transparency and heat resistance in the examples is based on the following criteria. (Transparency) ○: Haze 50% or less ×: Haze more than 50% (heat resistance) ○: No deformation ×: Deformation Example 1 PBT resin / Duranex 300FP [trade name of Polyplastics Co., Ltd.], PBT The copolymer resin, DURANEX 200JP (trade name, manufactured by Polyplastics Co., Ltd.) and PET resin, diamondite PA-50 (trade name, manufactured by Mitsubishi Rayon Co., Ltd.) were mixed at the ratio shown in Table 1 and mixed. It is supplied to an injection molding machine, J50E-C5A type (trade name, manufactured by Nippon Steel Works Co., Ltd.).
m, and then quenched and molded. Then, the mold was heated in the same shape as the cooling mold and heated to the temperature shown in Table 1, and the transparency of the obtained cup was 140 ° C. When the heat resistance of the sample left for 30 minutes was examined, the results shown in Table 4 were obtained.

[0016]

[Table 4]

Example 2 50 parts by weight of pellets of PBT resin, DURANEX 2002 (trade name of Polyplastics) and amorphous PET
A resin composition consisting of 50 parts by weight of pellets of resin FFS-30M [trade name of Kanebo Co., Ltd.] was supplied to a co-axial twin screw extruder having a diameter of 50 mmφ and compounded. J50E-C Injection molding machine equipped with a dies with four 2.8 mm illuminated switch buttons
After being supplied to the 5A type (described above) and molded by changing the temperature of the mold as shown in Table 2, heating is performed by a mold which is heated and adjusted to 140 ° C. in the same shape as the cooling mold. ,
The transparency of the obtained illuminated switch and the heat resistance of the device after being left for 30 minutes in an oven set to 140 ° C. were examined. The results shown in Table 5 were obtained.

[0018]

[Table 5]

EXAMPLE 3 A resin composition comprising 40 parts by weight of pellets of PBT resin / Duranex 2002 (supra) and 60 parts by weight of pellets of amorphous PET resin / FFS-30M (supra) was used to prepare a resin composition having a diameter of 50 mmφ. An injection molding machine equipped with a die for feeding the same direction twin-screw extruder, compounding it, and mounting the four thickest switch buttons with the thickest part of 4.0 mm.
It is supplied to J50E-C5A type (described above), rapidly cooled and molded. The molded article is annealed for 50 hours while changing the temperature of the oven as shown in Table 3, and then is cooled to the same shape as the cooling mold.
Table 6 shows a comparison between the transparency of the illuminated switch button obtained after heating in a mold heated to 40 ° C. and the heat resistance after being left in an oven set at 140 ° C. for 30 minutes. The results were as shown.

[0020]

[Table 6]

[0021]

The present invention relates to a method for producing a transparent heat-resistant molded article, which comprises 40 to 100 parts by weight of at least one kind of polybutylene terephthalate resin and at least one kind of crystalline PET resin 60 as described above. To 10 parts by weight of a resin composition (provided that PBT homopolymer 100
(Excluding parts by weight), injection-molded and quenched or gradually cooled in a molding die, or at least one type of PBT resin
Less than 0 parts by weight and at least one crystalline PET resin 9
Injection molding of the resin composition consisting of 0 to more than 60 parts by weight, annealing in a molding die or quenching in a molding die followed by annealing, or at least one type of P
A resin composition (excluding 100 parts by weight of a PBT homopolymer) comprising 60 to 100 parts by weight of a BT-based resin and 40 to 0 parts by weight of at least one amorphous PET-based resin is injection-molded to obtain a molding metal. The resin composition is quenched or slowly cooled in a mold, or a resin composition comprising 10 to less than 10 parts by weight of at least one PBT resin and 90 to 40 parts by weight of at least one amorphous PET resin. After annealing in a mold or quenching in a molding die, annealing is performed, and then heating and crystallization in a heating die. The advantage is that a transparent and heat-resistant plastic molded product that can be sterilized, hot-filled, or the like can be easily obtained.

Continued on the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical display location B29L 22:00

Claims (8)

(57) [Claims] 1. A resin composition comprising 40 to 100 parts by weight of at least one kind of polybutylene terephthalate-based resin and 60 to 0 parts by weight of at least one kind of crystalline polyethylene terephthalate-based resin (provided that polybutylene terephthalate alone is used). Injection molding and cooling with a molding die to obtain a transparent molded product, and then the temperature is higher than the cold crystallization temperature of the resin composition and lower than the melting point of the resin having the lowest melting point among the resins used. A method for producing a transparent heat-resistant injection-molded article, characterized in that the article is heated in a mold adjusted to a low temperature. 2. A resin composition comprising 60 to 100 parts by weight of at least one kind of polybutylene terephthalate-based resin and 40 to 0 parts by weight of at least one kind of amorphous polyethylene terephthalate-based resin (provided that polybutylene terephthalate is used alone). Injection molding and cooling in a molding die to form a transparent molded article, and then the melting point of the resin having a temperature not lower than the cold crystallization temperature of the resin composition and the lowest melting point among the resins used. A method for producing a transparent heat-resistant injection-molded article, wherein the article is heated in a mold that has been adjusted to a lower temperature. 3. Cooling of the molded article in the molding die is performed at a temperature not lower than the lowest glass transition point of the resin using the temperature of the molding die and lower than the highest glass transition point of the resin used. [However, polybutylene terephthalate resin (excluding polybutylene terephthalate homopolymer) 10
The method for producing a transparent heat-resistant injection-molded article according to claim 1 or 2, wherein in the case of 0 parts by weight, the polybutylene terephthalate resin has a temperature higher than the lowest glass transition point and lower than the lowest cold crystallization temperature]. . 4. A resin composition comprising at least one kind of polybutylene terephthalate-based resin in an amount of less than 10 to 40 parts by weight and at least one kind of crystalline polyethylene terephthalate-based resin in an amount exceeding 90 to 60 parts by weight during injection molding.
The temperature of the cooling mold is equal to or higher than the lowest glass transition point of the resin used and lower than the highest glass transition point of the resin used [however, polybutylene terephthalate resin (excluding polybutylene terephthalate homopolymer) In the case of 100 parts by weight, the polybutylene terephthalate resin has a temperature equal to or higher than the lowest glass transition point and lower than the lowest cold crystallization temperature.
Production of a transparent heat-resistant injection-molded article characterized by heating in a mold that is heated to a temperature higher than the cold crystallization temperature of the resin composition and lower than the melting point of the resin having the lowest melting point among the resins used. Method. 5. A resin composition comprising at least one kind of polybutylene terephthalate resin in an amount of less than 10 to 40 parts by weight and at least one kind of crystalline polyethylene terephthalate type resin in an amount of more than 90 to 60 parts by weight, which is quenched. The molded article obtained is a temperature not lower than the lowest glass transition point of the resin used and lower than the highest glass transition point of the resin used [however, polybutylene terephthalate resin (polybutylene terephthalate single weight) 100 parts by weight of the polybutylene terephthalate resin at a temperature higher than the lowest glass transition point and lower than the lowest cold crystallization temperature) for 1 minute to 50
After annealing for 0 hours or online in the manufacture of molded products, the mold heated and adjusted to a temperature lower than the melting point of the resin with the lowest melting point among the resins used above the cold crystallization temperature of the resin composition A method for producing a transparent heat-resistant injection-molded article, characterized by heating at a temperature. 6. The method for producing a transparent heat-resistant molded article according to claim 1, wherein the cooling in the molding die is quenched. 7. A resin composition comprising at least one kind of polybutylene terephthalate-based resin in an amount of less than 10 to 60 parts by weight and at least one kind of amorphous polyethylene terephthalate-based resin in an amount exceeding 90 to 40 parts by weight during injection molding. ,
The temperature of the cooling mold is equal to or higher than the lowest glass transition point of the resin used and lower than the highest glass transition point of the resin used [however, polybutylene terephthalate resin (excluding polybutylene terephthalate homopolymer) In the case of 100 parts by weight, the polybutylene terephthalate resin has a temperature equal to or higher than the lowest glass transition point and lower than the lowest cold crystallization temperature.
Production of a transparent heat-resistant injection-molded article characterized by heating in a mold that is heated to a temperature higher than the cold crystallization temperature of the resin composition and lower than the melting point of the resin having the lowest melting point among the resins used. Method. 8. A resin composition comprising 10 to less than 60 parts by weight of at least one polybutylene terephthalate-based resin and 90 to 40 parts by weight of at least one amorphous polyethylene terephthalate-based resin, which is quenched. Injection molding is performed, and the obtained molded article is used at a temperature higher than the lowest glass transition point of the resin to be used and lower than the highest glass transition point of the resin used [however, polybutylene terephthalate-based resin (polybutylene terephthalate alone) 100 parts by weight (excluding polymer) at a temperature higher than the lowest glass transition point of the polybutylene terephthalate-based resin and lower than the lowest cold crystallization temperature] for 1 minute to 50
A transparent heat resistance characterized by annealing for 0 hours or annealing online in the manufacture of molded products, and then heating in a mold that is heated to a temperature lower than the melting point of the resin with the lowest melting point among the resins used. Manufacturing method for injection molded products.