JPS6340747B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to polyester containers. More specifically, the present invention relates to a polyester container that can omit the complicated operation of separating components other than polyester when effectively reusing used empty containers. In recent years, thermoplastic polyesters such as polyethylene terephthalate have been used for various packaging containers due to their excellent mechanical properties, gas barrier properties, chemical resistance, fragrance retention, transparency, hygiene, etc. There is. Containers made of thermoplastic polyester usually have a main body made of polyester, but other parts of the container as a whole are made of components other than polyester. For example, stoppers are made of polyethylene or metal, labels are made of paper, and legs of pressurized containers for carbonated drinks and the like are made of polyethylene. Such containers are normally used as disposable containers, but from the standpoint of resource conservation and environmental protection, it is desired that the containers be recovered and reused effectively. Such recycling methods include reusing it as a polymer as a molding material, or decomposing it into terephthalic acid, which is the raw material for polyester, or its ester-forming derivative and ethylene glycol, purifying it, and then reusing it as a polymer raw material. method is known. However, in any of the recycling methods, it is necessary to separate components made of components other than polyester, such as metal materials such as aluminum stoppers, polyethylene stoppers, footrests, paper labels, etc. Methods for separating components other than polyester include, for example, using a detector to exclude magnetic substances such as iron, separating lightweight materials such as paper used for labels using compressed air, and separating aluminum used for caps. Possible methods include separating non-ferrous metals such as metals using eddy current, and separating heavy foreign substances such as polyethylene or glass used in footrests in an aqueous solution by utilizing the difference in specific gravity. As a result of intensive studies on containers that can be effectively recycled without performing such complicated separation operations, the inventor of the present invention found that if polyester components processed using a special molding technique are used in polyester containers, the desired container can be used. The inventors have discovered that it is possible to obtain the following, and have arrived at the present invention. That is, the present invention has the following features: 1. The container body is made of polyester A having ethylene terephthalate as the main repeating unit,
The material of the component parts of the container, including the stopper, lid, gripping handle, and footrest, excluding metal materials, is made of polyester B whose main repeating unit is ethylene terephthalate, and the container is made of polyester B whose main repeating unit is ethylene terephthalate. A polyester container with a label made of a shrunken cylindrical thin film made of C; When attaching a label made of polyester C, a cylindrical thin film body having a density of 1.38 g/cm ³ or less and a degree of plane orientation of 0.02 or more is placed over the outside of the body, and the polyester C constituting the thin film body is covered. This is a method for producing a polyester container, characterized by forming a label by shrinking the thin film at a temperature equal to or higher than the glass transition temperature of the polyester container. In the present invention, the polyester A constituting the container body is a thermoplastic polyester having ethylene terephthalate as a main repeating unit, and is mainly intended for use as a homopolymer of polyethylene terephthalate. Aromatic dicarboxylic acids such as dicarboxylic acid, diphenyl dicarboxylic acid, diphenoxyethane dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenylsulfone dicarboxylic acid, etc.; Alicyclic dicarboxylic acids such as hexahydroterephthalic acid, hexahydroisophthalic acid, etc. Acids; aliphatic dicarboxylic acids such as adipic acid, sebacic acid, azelaic acid, etc.; other difunctional carboxylic acids such as oxyacids such as P-β-hydroxyethoxybenzoic acid, ε-oxycaproic acid, etc.; , and/or a part of the ethylene glycol component, such as trimethylene glycol, tetramethylene glycol, hexamethylene glycol, decamethylene glycol, neopentylene glycol, diethylene glycol, 1,1-cyclohexane dimethylol, 1,4-cyclohexane dimethylol ,
One or more polyfunctional compounds of other glycols and functional derivatives thereof such as 2,2-bis(4'-β-hydroxyethoxyphenyl)propane and bis(4'-β-hydroxyethoxyphenyl)sulfonic acid It may also be a copolymer substituted with and copolymerized. The proportion of copolymerized components in the copolyester is
It is preferably about 10 mol% or less. In the present invention, the component parts of the container, namely the lid,
The stopper, the gripping handle, and the base are composed of polyester B having ethylene terephthalate as a main repeating unit. Further, the thin film material serving as the label attached to the body of the container body is also composed of polyester C having ethylene terephthalate as a main repeating unit. Here, polyester B and polyester C are homopolymers of polyethylene terephthalate (main target), which are the same or have different degrees of polymerization or modification, or copolymerized components of a part of the terephthalic acid component and/or a part of the ethylene glycol component. It may also be a substituted copolymer. Such copolymerization components include those exemplified as the copolymerization component of polyester A above. The proportion of copolymerized components in this copolymer varies depending on the type of component, and is preferably about 30 mol% or less for the stopper and gripping handle, and about 50 mol% or less for the lid and label. . When the polyester container of the present invention is used as a pressurized container for carbonated beverages, etc., a leg base is usually attached to the polyester container, and the leg base and the adhesive that may be used to attach the leg base are also as described above. It is preferably made of polyesters A to C and a polyester adhesive. When a copolymer is used as the polyester B constituting the footrest, it is preferably copolyethylene terephthalate with a copolymerization component of about 30 mol% or less. The container body referred to in the present invention may be formed by injection blow molding, for example.
A bottle-shaped container made by extrusion blow molding or a cup-shaped container made by thermoforming, which can be filled with a liquid or solid content, and especially a bottle-shaped container having a biaxially oriented portion (so-called biaxial Containers obtained by stretch blow molding are the main target because they are used in large quantities as food or beverage containers. Furthermore, the constituent parts of the polyester container are, for example, those described below. Label: A cylindrical thin film made by extruding polyester C into a pipe shape, stretched in the horizontal direction at a temperature range that substantially causes molecular orientation, is placed over the container, and attached to the container by heat shrinkage. Leg: molded by injection molding, or thermoformed from a polyester sheet and bonded to the bottom of the bottle with adhesive or thermal bonding, or the leg is bonded to the bottle by thermal deformation. thing. Stoppers and handles: Molded by injection molding. Wrap: A cylindrical film formed by inflation, etc., with both ends heat-sealed. In the case of a bottle container, such container components are mounted, for example, as shown in the accompanying drawings. 1 and 2 are a partial side view and a partial sectional view of the bottle. In Figure 1, 1 is the bottle body, 2
3 is a label, 3 is a stand for self-supporting, 4 is a stopper, 5 is an inner lid of the stopper, and 6 is an adhesive layer between the stand and the bottle. Further, in FIG. 2, 7 indicates a handle. Third
FIG. 4 is an enlarged partial side view and partial cross-sectional view of the bottom of the bottle. 8 is a recess made in the bottle body 1, 9 is the upper end of the leg stand 6, 10 is the bottom of the bottle, 1
1 indicates an adhesive layer. When manufacturing a polyester container with a label in the present invention, it is preferable to cover the thermoplastic polyester container body with a cylindrical thin polyester material and then heat shrink the polyester container so that the polyester container is brought into close contact with the container body to form a label. In this case, the density of the thin film is preferably 1.38 g/cm ³ or less; if the density is greater than 1.38 g/cm ³ , uniform shrinkage becomes difficult, which is not preferred.
In addition, it is preferable that the degree of plane orientation of the thin film is 0.02 or more, especially the degree of plane orientation in the axial direction of the cylinder (△ny−z).
It is preferable that the degree of plane orientation (△nx−z) in the lateral direction is larger than that. Most preferably, △nx−z≧
0.05, in the range of △nx−z/△ny−z≧2,
The dimensional accuracy of the label in the vertical direction becomes good and the adhesion becomes good. The temperature at which the thin film is shrunk is preferably higher than the glass transition temperature (Tg) of polyester C constituting the thin film; if this temperature is lower than Tg, the adhesion of the label will deteriorate.
The upper limit of the shrinkage temperature is preferably set to a temperature at which the thermoplastic polyester container body is not substantially deformed. The thickness of the label is preferably 1/10 or less of the thickness of the container body, for example, 50μ or less. If the label is too thick, the container body may also shrink and deform when the label is heat-shrinked, which is not preferable. Further, as a method of joining the leg base to the bottom of the bottle, for example, as shown in FIG. 3, a method is employed in which a recess as shown by 8 is made in the bottle body and the upper end 9 of the leg base is pushed into the part 8 by thermal deformation. As shown in FIG. 4, it is preferable to use a method of bonding the foot stand and the bottle by thermal bonding. 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. Orientation degree (△n): Measure the refractive index in the thickness direction and in the plane direction of a sample cut from a container using a sodium D line at a temperature of 25°C using an Atsube refractometer equipped with a polarizing plate. The difference was determined by calculation. 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. Density (ρ): Measured at 25°C using a density gradient tube made from carbon tetrachloride and n-heptane. Examples and Comparative Examples Polyethylene terephthalate with IV = 0.74, Tg = 77°C, and Tsp = 259°C was heated to 160°C in a dehumidifying dryer.
The chips were dried for 4 hours to obtain dry chips with a moisture content of 0.01% or less. Using this dry chip, an 8-ounce injection molding machine (M-100 model manufactured by Meiki Manufacturing Co., Ltd.) and a hot runner type two-cavity mold were used to mold the straight body with an outer diameter of 25 mm, a length of 175 mm, and a wall thickness of 3.5 mm. A bottomed preform weighing 50 gr was molded. The molding conditions are cylinder set temperature 265-270℃ (resin temperature at nozzle part)
285℃), injection pressure 500-700Kg/cm ³ , 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. The obtained preform was substantially amorphous with good transparency. Using this preform, a stretch blow molding machine (manufactured by Cincinnati Milacron Co., Ltd.)
RHB-L type machine), body diameter 80mm, height
A 260 mm round-bottom 1 liter bottle shaped like a carbonated beverage 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: 6 Kg/cm ² G Secondary pressure: 15 to 18 Kg/cm ² G The physical properties of the bottle thus obtained were as follows. Body wall thickness: 0.35 to 0.45mm Transparency: Good Body light transmittance: 90% Drop strength: After filling a bottle with H ₂ O and capping it, drop it from a height of 2m on a concrete floor with the bottom facing down. It did not explode when dropped. Internal pressure strength: As a result of gradually applying water pressure inside the bottle, the bottle burst at a pressure of 16 kg/cm ² G. Label: Polyethylene terephthalate particles with an intrinsic viscosity of 0.65, a softening point of 256°C, and a glass transition temperature of 78°C are dried at 160°C for 5 hours in a hot air dryer.
After setting the moisture content in the particles to 0.01% by weight, a pipe-shaped molded product with an outer diameter of 11 mm and a wall thickness of approximately 1 mm was extruded using an extruder at 270°C, and immediately cooled with water to form a pipe with good transparency. . Next, this pipe is immersed in hot water at 90°C, stretched approximately 1.5 times in the axial direction, expanded horizontally by approximately 8 times with pressurized air blown into the pipe, and immediately cooled to reduce the diameter to approximately 1.5 times. A cylindrical thin film of 85 mm and wall thickness of about 0.08 mm was obtained. After printing on the surface of the film, the width is approximately 80 mm.
After cutting the thin cylindrical film into pieces of 1.5 mm and covering the outside of the body of the bottle obtained by the above method with an outer diameter of 82 mm, hot air at about 100°C was blown to shrink the cylindrical thin film. A label was attached to the section. Table 1 shows the results of experiments conducted in the same manner as above, with various molding conditions and shrinkage conditions for cylindrical thin films.

[Table] Leg stand: A polyethylene terephthalate sheet with an intrinsic viscosity of 0.68, a softening point of 260°C, a glass transition temperature of 80°C, and a wall thickness of 2 mm is heated to approximately 100°C and then vacuum formed to create a cylindrical portion with an inner diameter of approximately 82 mm and a bottom shape. 1st
A footrest as shown in Figure 3 was molded. Attaching the footrest to the bottle: A copolymerized polyester made by polycondensing terephthalic acid, adipic acid, and ethylene glycol in a high vacuum in the presence of a catalyst, with a terephthalic acid/adipic acid component ratio of 1/1 and a softening point of 151°C. I got it. The copolymerized polyester was melted and adhered to the base, and immediately after the bottle was attached, the base was attached to the bottle by cooling and solidifying. In addition, after attaching the leg to the bottle, a stainless steel metal rod with a 6 mm diameter and a smooth tip heated to 200°C was pressed from the outside of the leg for about 5 seconds to soften part of the leg and attach it to the bottle. A method of attaching it was also possible. Plug: After drying polyethylene terephthalate particles with an intrinsic viscosity of 0.85 and a softening point of 258°C with hot air, a plug-shaped molded product is produced using an injection molding machine with a mold that has a screw-like shape on the inside and a cylindrical shape on the outside (mold temperature: 10°C).
℃, cylinder set temperature 265-280℃) was molded. Next, dimethyl terephthalate, ethylene glycol, and polytetramethylene glycol (average molecular weight 800), which were separately molded with a wall thickness of 1 mm, were transesterified in the presence of a catalyst and polytetramethylene glycol was polycondensed under high vacuum.
A polyester stopper was prepared by punching out a block copolymer sheet containing 30% by weight into a circular shape and inserting it into the stopper as an inner lid. The entire container thus obtained as shown in FIG. 1 was pulverized using a pulverizer, and after drying, a test piece with a wall thickness of 2 mm was molded using the bottle and injection molding machine described above. Table 2 shows the physical properties of the molded product. Similarly, 15% of glass fiber with a length of 3 mm was mixed,
A strand with a diameter of about 2 mm was extruded using an extruder and cut into lengths of about 2 mm to obtain glass fiber-containing pellets. Next, the wall thickness is 0.5 using an injection molding machine.
A plate-shaped sample of mm was molded. Table 2 shows the physical properties of the molded product. After drying the above-mentioned pulverized material, use an extruder to reduce the thickness to 0.2
A thread-like extrusion molded product of mm was molded. Show molding status
Shown in 2. For comparison, after thoroughly washing a commercially available polyester bottle for soybean oil, and then peeling off the polyethylene stopper and paper label, the cases were crushed using a crusher, and the cases were crushed with the stopper and paper label intact. The same molding as above was carried out. The results are shown in Table-2. Furthermore, for carbonated drinks sold in the United States,
Similar molding was attempted for containers with polyethylene bases, paper labels, and aluminum stoppers similar to PET bottles. The results are shown in Table-2.

【table】

[Table] As shown above, according to the polyester container of the present invention, used empty containers can be recycled without complicated separation operations or at all.

[Brief explanation of drawings]

FIG. 1 is a partial side view and partial cross-sectional view of a container with a stopper, an inner lid, a label, and a base. FIG. 2 is a partial side view and partial cross-sectional view of a container with a stopper, an inner lid, a label, and a handle. FIG. 3 is a partial side view and a partial sectional view showing a state in which the leg base is joined to the bottom of the bottle. FIG. 4 is a partial side view and a partial cross-sectional view showing a state in which the leg base is thermally bonded to the bottom of the bottle.

Claims (1)

[Scope of Claims] 1. The main body of the container is made of polyester A containing ethylene terephthalate as a main repeating unit, and the materials of the component parts of the container, including the stopper, lid, gripping handle, and footrest, do not contain ethylene terephthalate, except for metal materials. Polyester B as the main repeating unit
1. A polyester container comprising a label made of a shrunken cylindrical thin film made of polyester C whose main repeating unit is ethylene terephthalate. 2. When attaching a label made of polyester C, whose main repeating unit is ethylene terephthalate, to the body of a container body made of polyester A, whose main repeating unit is ethylene terephthalate, it must have a density of 1.38 g/cm 3 or less and a surface area of 1.38 g/cm ³ or less. A cylindrical thin film body having an orientation degree of 0.02 or more is placed over the outside of the body, and the thin film body is shrunk at a temperature equal to or higher than the glass transition temperature of the polyester C constituting the thin film body to form a label. A method for manufacturing polyester containers.