JPH0137253B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a polyester container and a method for manufacturing the same, and more particularly to a container made of modified polyester having excellent heat shrinkage resistance and a method for manufacturing the same. Polyester containers have recently been widely used as containers for foods, beverages, cosmetics, and the like. In particular, biaxially oriented bottles made of polyethylene terephthalate have the advantage of strong mechanical strength, less permeability to gases such as oxygen and carbon dioxide, and excellent transparency compared to containers made of polyethylene or polypropylene. It has excellent performance as containers for beverages, foods, cosmetics, etc. However, conventional polyethylene terephthalate containers have the disadvantage of poor heat shrinkage resistance, and when filled at temperatures above 70°C, low-stretch areas such as the shoulders and bottom of the bottle deform, and the volume decreases by 3%. It shrinks and cannot withstand practical use at high temperatures. Various methods have been proposed to improve the heat shrinkage resistance, mainly through thermal treatment, as a method to improve the heat shrinkage resistance. However, there are drawbacks such as the internal volume being uneven or the container being partially deformed.
In addition, containers that have been thermally treated to the extent that defects such as uneven internal volume and partial deformation do not occur,
The filling temperature that can withstand use is about 80° C. at most, and if it is filled at a higher temperature than this, volume shrinkage, deformation, seal leakage at the stopper, etc. occur, making it unusable. As a result of intensive research in order to develop a polyester container that does not have these drawbacks, the present inventor blended polycarbonate resin with polyester resin in a specific ratio, and controlled the blow mold temperature during blow molding to a specific temperature range. The present invention has been achieved based on the discovery that if the container is molded while maintaining the temperature, it is possible to obtain a container with extremely little thermal shrinkage and no seal leakage at the stopper after high-temperature filling. That is, the present invention comprises: 1 a composition formed by mixing a polycarbonate resin (B) with a polyethylene terephthalate resin (A) having an intrinsic viscosity of 0.5 or more at a weight ratio of about 0.05≦(B)/(A)≦1; A polyester container whose body is biaxially stretched and whose volume shrinkage is 2% or less when hot water at 90°C is filled into the container and left to cool; 2. An intrinsic viscosity of 0.5. After mixing and melting the above polyethylene terephthalate resin (A) and polycarbonate resin (B) at a weight ratio in the range of approximately 0.05≦(B)/(A)≦1, the polyethylene terephthalate resin (A) and the polycarbonate resin (B) are mixed and melted at a temperature below the glass transition temperature of the polyethylene terephthalate resin. When producing a container by injection molding a bottomed hollow preform using a mold set to Characterized by a temperature of 110℃ or higher,
A method for manufacturing a polyester container that has a volumetric shrinkage of 2% or less when the container is filled with hot water at 90°C and left to cool. It is. The polyester in the present invention is mainly a homopolymer of polyethylene terephthalate, but a part of the terephthalic acid component is, for example, isophthalic acid, naphthalene dicarboxylic acid, diphenyl dicarboxylic acid, diphenoxyethane dicarboxylic acid, diphenyl ether dicarboxylic acid. , aromatic dicarboxylic acids such as diphenylsulfonedicarboxylic acid;
Alicyclic dicarboxylic acids such as hexahydroterephthalic acid, hexahydroterephthalic acid, hexahydroisophthalic acid, etc.; Aliphatic dicarboxylic acids such as adipic acid, sebacic acid, azelaic acid, etc.; P-β-
With one or more other difunctional carboxylic acids such as oxyacids such as hydroxyethoxybenzoic acid, ε-oxycaproic acid, etc., and/or a portion of the ethylene glycol component, such as trimethylene glycol, tetramethylene glycol, hexa Methylene glycol, decamethylene glycol, neopentylene glycol, diethylene glycol, 1,1-cyclohexane dimethylol, 1,4-cyclohexane dimethylol, 2,2-bis(4'-β-hydroxyethoxyphenyl)propane, bis( 4′−
Copolymerization with substitution within 15 mol%, preferably within 5 mol%, of one or more polyfunctional compounds of other glycols and functional derivatives thereof such as β-hydroxyethoxyphenyl) sulfonic acid. It may also be a diluted copolymer. The intrinsic viscosity of such polyester is 0.5 or more,
Preferably it is 0.6 or more. If the intrinsic viscosity is less than 0.5, uneven thickness may occur during blow molding, and the mechanical properties of the container may deteriorate, which is not preferable. The polycarbonate resin used in the present invention is
Any can be used regardless of its chemical structure or average molecular weight, but particularly preferred among them are 4,4'-dihydroxydiarylalkane polycarbonates, such as 4,4'-dihydroxydiphenyl-2,2 - A polycarbonate containing propane as a diol component. The average molecular weight of such polycarbonate varies depending on the type of resin, but in the case of 4,4'-dihydroxydiarylalkane carbonate resin, it is 20,000.
~50,000 is preferable, and if you use one with a melt viscosity comparable to that of polyester resin when melted,
This is preferred because the dispersion in the polyester resin becomes particularly good. In the present invention, a mixture of polyester resin and polycarbonate resin is used, and the weight ratio of polyester resin (A) and polycarbonate resin (B) is 0.05≦(B)/(A)≦1, and ( (B)/(A) is a weight ratio), preferably 0.1≦(B)/(A)≦0.2.
When the mixing ratio (B)/(A) is smaller than 0.05, the effect on heat shrinkage resistance is small. Also, if (B)/(A) is larger than 1, the stretchability will be poor when forming the container,
This is not preferable because it becomes difficult to make a container with a desired shape. The container in the present invention is made of a composition in which polyester resin (A) and polycarbonate resin (B) are mixed in the above mixing ratio, and the body portion thereof is biaxially stretched. The stretching ratio is 4 in terms of area ratio.
It is preferable to double or more. For example, it takes the shape of a bottle-shaped hollow body obtained by blow molding, a cup-shaped container obtained by vacuum forming, a tray-shaped container, etc. In order to improve the heat resistance of the container of the present invention, it is necessary to biaxially stretch the body of the container. Furthermore, it is preferable that the density is within a specific range. When polyethylene terephthalate resin and polycarbonate resin are simply blended and, for example, injection molded, a ratio of 50% or more is required to obtain a molded product with a heat distortion temperature approximately 10°C higher than that of the polyethylene terephthalate resin. It is necessary to mix the polycarbonate resin, but when the stretched portion is heated, for example, by a mold as in the present invention, the ratio of the polycarbonate resin is 0.05≦(B)/(A).
It is sufficient that 0.1≦(B)/(A). The mold temperature at this time is set to be higher than the glass transition temperature of the polyethylene terephthalate resin (approximately 80°C or higher), preferably 100°C or higher. The density (ρ) of the stretched part of the container is: ρ≧ρ _A [(A)/{(A)+(B)}] +ρ _B [(B)/{(A)+(B)}] +0.01 It is preferable that it be within a certain range. (However, ρ _A : Density of amorphous polyethylene terephthalate resin (approximately 1.33),
ρ _B : Density of polycarbonate resin (approximately 1.21)) The container of the present invention exhibits a slight decrease in internal volume of 2% or less when filled with 90° C. hot water and left to cool. Moreover, it is characterized by extremely good sealing properties after being capped. Hereinafter, the present invention will be explained in detail with reference to Examples. The measurement conditions for the main characteristic values are as follows. Glass transition temperature (Tg): A sample melted at 290℃ and then rapidly cooled to 0℃ was measured using a differential calorimeter (DSC- manufactured by PerkinElmer).
1) at a heating rate of 10℃/min. Intrinsic viscosity [IV]: Measured at 35°C using o-chlorophenol as a solvent. Density [ρ]: Measured at 25°C using a density gradient tube of n-heptane-tetrachloride mixture. Softening point (TSP): Polymer chips (shape approx. 4mm x 4mm x 2mm)
The material treated at 140℃ for 1 hour was placed in a softening point tester, a load of 1kg was applied to a needle with a tip with a cross-sectional area of ^1mm2 , and the temperature was raised at a rate of 50℃/hr to determine the penetration depth. The temperature at which the temperature reached 1 mm was measured, and that value was taken as the softening point. Example 1 and Comparative Example 1 Polyethylene terephthalate with IV = 0.71, Tg = 77°C, and Tsp = 259°C and polycarbonate with a molecular weight of about 30,000 were mixed in the form of chips at the ratio shown in Table 1, and then dehumidified. 130℃ in dryer
The chips were dried for 8 hours to obtain dry chips with a moisture content of 0.01% or less. Using this dry chip, an 8-ounce injection molding machine (Meiki Seisakusho M-100 model machine) and a hot liner type two-cavity mold were used to mold the straight body part with an outer mold of 25 mm, a length of 175 mm, a wall thickness of 3.5 mm, and A bottomed preform weighing 50 g was molded. The molding conditions are cylinder set temperature 265-270℃ (resin temperature at nozzle part)
285℃), injection pressure 500-700Kg/cm ² , molding cycle
The mold cooling water temperature was 10 to 20°C, and the residence time of the resin in the injection molding machine cylinder was about 2 minutes. Using this preform, a stretch blow molding machine (RHB-L type machine manufactured by Cincinnati Milacron Co., Ltd.) was used to mold the body with a diameter of 75 mm at the top, 80 mm at the bottom, and a height of 260 mm.
A bottle having the shape of a commercially available 1-mm sauce bottle was molded. The blow molding conditions at this time were as follows. Preform outer surface temperature upon completion of preheating: 100 to 130
°C Blow pressure: Primary pressure 6Kg/cm ² G Secondary pressure 15-18Kg/cm ² G Actual contact time between blow molded product (bottle) and mold:
4 seconds Mold temperature: Shoulder 100-110℃ Body 110-120℃ Bottom 90-100℃ Inside the bottle obtained under conditions of 90℃ and 95℃
Immediately after filling, the bottles were capped and left to cool until the liquid temperature dropped to below 20°C, and then the internal volume of the bottle was measured, and the volume shrinkage rate relative to the internal volume of the bottle when filled with hot water was measured. The results are shown in Table-1. 【table】

Claims (1)

[Claims] 1. A body comprising a composition obtained by mixing a polyethylene terephthalate resin (A) with an intrinsic viscosity of 0.5 or more and a polycarbonate resin (B) at a weight ratio of approximately 0.05≦(B)/(A)≦1. A container whose parts are biaxially stretched,
A polyester container having a volume shrinkage rate of 2% or less when the container is filled with hot water at ℃ and allowed to cool. 2. After mixing and melting polyethylene terephthalate resin (A) with an intrinsic viscosity of 0.5 or more and polycarbonate resin (B) at a weight ratio in the range of approximately 0.05≦(B)/(A)≦1, glass rearrangement of the polyethylene terephthalate resin is performed. When manufacturing a container by injection molding a bottomed hollow preform using a mold set at a temperature below the temperature of A method for manufacturing a polyester container, characterized in that the temperature is 110°C or higher, and the volumetric shrinkage rate when the container is filled with hot water at 90°C and left to cool is 2% or less.