JP2001328614A - Heat-resistant container and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a container composed mainly of a polyethylene terephthalate and provided with superior heat resistance, transparency and impact resistance and capable of dealing with the high rate production. SOLUTION: The container is manufactured by molding a polyester sheet composed mainly of a polyethylene terephthalate and provided with orientation crystals generated by orientation and crystallinity of the inner face of the container is larger than the crystallinity of the surface outside the container on the side wall section.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-resistant container made of a polyester resin mainly composed of polyethylene terephthalate and a method for producing the same. The present invention relates to a heat-resistant container having excellent heat resistance and a method for producing the heat-resistant container capable of efficiently forming the heat-resistant container at high speed.

[0002]

2. Description of the Related Art Polyethylene terephthalate resin (PE)
T resin) is excellent in transparency and low in raw material cost as compared with polyolefin resin and polystyrene resin.
In addition, since a recycling route has been established, it is widely used as a container for foods and beverages. However, since PET resin itself does not have heat resistance,
In applications that are subjected to high-temperature filling, such as hot packs, there is a possibility of contraction and deformation, and it is necessary to improve the heat resistance. As a method for improving the heat resistance of a molded article made of PET resin, it has been conventionally proposed to increase the crystallinity of the molded article. For example, Japanese Patent Publication No. 4-36534 describes a polyester container in which the crystallinity of the bottom and side portions of the container is 20% or more, and the heat bonding portion (flange portion) with the lid material is less than 20%. And this container is
It also describes that it is useful as an orbable tray.

[0003]

According to the above prior art, a heat-plasticized amorphous polyester sheet is molded into a tray or the like by using a mold maintained at a crystallization temperature, and is formed into a bottom portion and / or a tray. Although the side portion is thermally crystallized, in the container made of the polyester resin, thermal crystallization is promoted without molecular orientation in an unstretched state. There is a disadvantage that the property cannot be imparted to the container. Further, since the oriented crystallization by stretching is insufficient, impact resistance such as drop strength is poor, and brittle fracture occurs. Furthermore, since the degree of crystallinity is improved only by thermal crystallization of the molded article, there are disadvantages that the time required for molding is long, high-speed production is difficult, and productivity is poor.

Accordingly, an object of the present invention is to provide a container made of a polyester resin mainly composed of polyethylene terephthalate, which is excellent in heat resistance, transparency and impact resistance, and which can cope with high-speed production, and a method for producing the same. To offer.

[0005]

According to the present invention, there is provided a container obtained by molding a polyester sheet containing polyethylene terephthalate as a main component, the container having oriented crystals by stretching, and a side wall of the container. Further, there is provided a heat-resistant container characterized in that the crystallinity of the inner surface of the container is larger than the crystallinity of the outer surface of the container. According to the present invention, a polyester sheet containing polyethylene terephthalate as a main component is heated to a stretching temperature, and the polyester sheet is maintained at a temperature equal to or higher than the crystallization temperature of the polyester sheet. A method for producing a heat-resistant container is provided, wherein the plug and a mold maintained at a temperature equal to or lower than the glass transition point of the polyester sheet are pressure-formed.

[0006] In the method for producing a heat-resistant container of the present invention: 1. The ratio (H / D) of the height (H) of the container to the outer diameter (D) of the container is 1.3 or more; 2. holding the polyester sheet being formed on the plug for at least 2 seconds, performing heat setting, and then performing pressure forming; It is particularly preferable that the clearance between the outer surface of the plug and the inner surface of the mold is in the range of 1/4 to 5/6 of the sheet thickness.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In the heat-resistant container of the present invention, a polyester sheet containing polyethylene terephthalate as a main component is heated to a stretching temperature, and the polyester sheet is heated to a crystallization temperature or a crystallization temperature of the polyester sheet. It is obtained by press-forming with a plug maintained at the above temperature and a mold maintained at a temperature equal to or lower than the glass transition point of the polyester sheet. That is, the polyester sheet is stretched and heat-fixed by a plug heated to a high temperature above the crystallization temperature of the polyester sheet and a mold maintained at a low temperature below the glass transition point of the polyester sheet, By generating and growing an oriented crystal on the side wall of the substrate and removing the stretching strain, it is possible to provide a container having significantly improved heat resistance and impact resistance. Further, in the heat-resistant container of the present invention, since the side wall portion of the container is highly oriented, the side wall of the container is remarkably excellent in transparency and impact resistance such as drop impact.

In the heat-resistant container of the present invention, the crystallinity of the inner surface of the container is larger than the crystallinity of the outer surface of the container in each part except the flange portion and the bottom portion of the container. This is due to the method of manufacturing the container. That is, in the method for producing a heat-resistant container of the present invention, in the pressure forming, the temperature of the plug contacting the inner side of the container of the polyester sheet is as high as the crystallization temperature of the polyester sheet or higher. Since the temperature of the mold that contacts the outer side of the container of the polyester sheet is lower than the glass transition point of the polyester sheet, the temperature of the mold is higher than that of the outer surface of the container that does not directly contact the high-temperature plug. Crystallization proceeds remarkably on the surface serving as the inner surface of the container in contact with. As a result, as shown in FIG. 1, the degree of crystallinity on the inner surface of the container is higher than the degree of crystallinity on the outer surface of the container.

As described above, in the heat-resistant container of the present invention, the side wall is crystallized, but the side wall of the container is oriented and crystallized by stretching, and the bottom of the container is oriented and crystallized when the degree of stretching is large. However, even when the degree of stretching is small, the contact time with the plug is the longest, so that processing strain is reduced, and in some cases, thermal crystallization is performed. Therefore, the degree of crystallinity of the side wall portion varies depending on the position of the container, but is determined by a density gradient tube method described later.
%, Preferably in the range of 20 to 40%, and the difference in crystallinity between the inner surface of the container and the outer surface of the container is 1%.
It is desirable to be about 15%.

The fact that the heat-resistant container of the present invention is excellent in heat resistance is apparent from FIG. 2 showing the relationship between the filling temperature and the rate of change in the internal volume. That is, the following equation (1): The internal volume change rate (%) represented by represents the rate of change of the internal volume before and after filling, and this value is 4%
It is said that there is no practical problem if the temperature is within the above range. However, the heat-resistant container of the present invention has an internal volume change rate of 4% or less even at a filling temperature of 90 ° C. It is clear that, even when filling is performed, shrinkage deformation and the like are effectively prevented, and heat resistance is improved.

3 to 7 for explaining the method of manufacturing the heat-resistant container of the present invention, FIG. 3 shows a sheet 4 in which a plug 1 and a clamp mold 2 driven by an air cylinder are set on the mold 3. FIG. 7 is a diagram showing a neutral state before descending to the position shown in FIG. FIG. 4 is a view showing a process in which the clamp mold 2 descends before the plug 1 to clamp the sheet 4. FIG. 5 is a view showing a stretching step and a heat setting step. As shown in FIG.
Is stretched and formed into a container shape, and then the plug is kept in a lowered state, and heat setting is performed with the plug. Therefore, the polyester sheet is adjusted to a temperature equal to or higher than the stretching temperature, and the plug temperature is adjusted to a temperature equal to or higher than the crystallization temperature of the polyester sheet.

FIG. 6 is a view showing a compressed air process. After heat setting, shaping is performed by compressed air. However, in the heat-resistant container of the present invention, since heat setting has already been performed by a high-temperature plug, gold The temperature of the mold is set to a low temperature equal to or lower than the glass transition point of the polyethylene sheet, whereby the outer surface of the container comes into contact with the mold, is cooled, and the shape is fixed. FIG. 7 is a view for explaining the mold release step. The plug 1 and the clamp mold 2 are lifted in this order, and the mold can be released. The sex container is completed.

[0013] As described above, in plug-assist air-pressure or vacuum forming, the sheet is stretched in the container axial direction by the plug to form a container having a desired shape, and then the plug is held down and heat-set. I do. Thereafter, the container is formed by shaping the mold with compressed air.

In the present invention, it is particularly preferable that the ratio H / D between the height (H) of the container and the outer diameter (D) of the container is 1.3 or more. The following formula (2) C = (△ Hm- △ Hc) / △ Hm (2) in each part of the heat-resistant container of the present invention In the formula, △ Hm is measured by a differential scanning calorimeter (DSC). ΔHc is the differential scanning calorimeter (DS)
In FIG. 8 showing the relationship of the crystallization tendency (C) defined by the crystallization heat value measured by C), H / D
= 1.4 (C)
Is 1.0, crystallizing in all parts of the container,
In the case of the container with H / D = 1.3, the crystallization tendency (C) was 1.0 in each part except the bottom part, whereas H / D = 1.3.
In the container of 1.2, only the upper part D is substantially 1, and H / D =
It is clear that the crystallization tendency (C) is inferior to that of the container of 1.3 or more.

The following formula (3) U = H (010) / H (-110) at each part of the heat-resistant container of the present invention (3) where H (010) is measured by X-ray diffraction. Surface index (01
FIG. 9 shows the relationship between the orientation tendency (U) defined by the diffraction intensity of (0) and H (−110) being the diffraction intensity of the plane index (−110) measured by X-ray diffraction. , H
The container with /D=1.4 shows a high orientation tendency (U) of 1.20 or more also in the bottom portion A and the upper portion D of the container.
In the case of D = 1.3, the orientation tended to be slightly oriented in the bottom part A (U).
Is lower than 1.05 at any part, whereas at H / D = 1.2, the orientation tendency (U) at the bottom part A and the upper part D of the container is lower than 1.05.
It is clear that the orientation tendency (U) is inferior to that of /D=1.3 or more. Further, in FIG. 10 showing the relationship between the thickness of each part of the heat-resistant container of the present invention, for example, when a polyester sheet thickness of 1.2 mm is used, H
The container with /D=1.4 or more is stretched to a small thickness of 0.30 mm or less in both the bottom portion and the side wall portion, whereas the container with H / D = 1.3 or less has the side wall portion. Is 0.30 mm or less, but it is clear that the bottom portion is about 0.50 mm and the bottom portion is not stretched as compared with the side wall portion. That is, containers with H / D = 1.3 or more are:
The crystallization tendency (C) and the orientation tendency (U) are large.
As shown in Table 2, it is excellent in heat resistance and impact resistance. Further, in the heat-resistant container of the present invention, as described above, all parts of the side wall are crystallized, but the crystallinity of the side wall is measured by a density gradient tube method described later. %, Preferably in the range of 20 to 40%.

In the method for producing a heat-resistant container of the present invention,
Put the molded polyester sheet on the plug 2
It is preferable to perform heat setting while holding for at least 2 seconds, particularly 2 to 3 seconds, and then perform pressure forming. This allows
Heat setting is promoted, and molding distortion due to processing is sufficiently reduced, crystallization is promoted, and heat resistance can be improved.

In the method for producing a heat-resistant container of the present invention,
It is preferable that the clearance between the outer surface of the plug and the inner surface of the mold is in the range of 1/4 to 5/6 of the sheet thickness. As a result, it is possible to minimize the molding distortion caused by the shaping of the mold by the pressurized air, and it is possible to suppress the amount of deformation at the time of filling the container at a high temperature.

FIGS. 11 and 12 show the relationship between the plug temperature or the plug hold time and the internal volume change rate (%) represented by the above equation (1). The internal volume change rate (%) indicates the rate of change in the internal volume before and after filling. According to FIGS. 11 and 12, the higher the plug temperature and the longer the plug hold time, It is understood that when the time is 2 seconds or longer, the rate of change in internal volume is small, and deformation due to heat is small, that is, heat resistance is improved.

In the present invention, a polyester sheet containing polyethylene terephthalate as a main component is used. As the polyester sheet, a polyester single layer sheet or a multilayer sheet can be used. Polyethylene terephthalate, which is a main component of the polyester sheet used in the present invention, is a polyester in which 50% by mole or more of a carboxylic acid component is composed of a terephthalic acid component and 50% by mol or more of an alcohol component is an ethylene glycol component. Polyester is
It may be a homopolyester, a copolyester, or a blend of two or more of these.

Examples of the carboxylic acid component other than the terephthalic acid component include isophthalic acid, naphthalenedicarboxylic acid, p-
β-oxyethoxybenzoic acid, biphenyl-4,4′-
Examples thereof include dicarboxylic acid, diphenoxyethane-4,4'-dicarboxylic acid, 5-sodium sulfoisophthalic acid, hexahydroterephthalic acid, adipic acid, sebacic acid, trimellitic acid, and pyromellitic acid.

On the other hand, alcohol components other than ethylene glycol include 1,4-butanediol, propylene glycol, neopentyl glycol, 1,6-hexylene glycol, diethylene glycol, triethylene glycol, cyclohexanedimethanol and bisphenol A. Examples include alcohol components such as lenoxide adducts, glycerol, trimethylolpropane, pentaerythritol, dipentaerythritol, and sorbitan.

The polyester sheet used in the present invention is:
As long as it contains the largest amount of polyethylene terephthalate, it may be a copolymer with the above-mentioned other polyester or a blend with another thermoplastic resin. For example, but not limited to, polyethylene / butylene terephthalate, 2,6-naphthoate, isophthalate, these and polybutylene terephthalate, polybutylene terephthalate / isophthalate, polyethylene-2,6-naphthalate, polybutylene terephthalate / adipate, Polyethylene-2,6-naphthalate /
A blend of one or more of isophthalate and polybutylene terephthalate / adipate with polyethylene terephthalate can be given.

The polyester should have a molecular weight in the range of film formation and an intrinsic viscosity [η] measured using a phenol / chlorotetraethane mixed solvent as a solvent.
Is preferably 0.5 or more, especially 0.6 to 1.5 in terms of moldability, mechanical properties, heat resistance and the like.

In the polyester, an ethylene polymer,
At least one modified resin component such as a thermoplastic elastomer, polyarylate, and polycarbonate can be contained. The modifying resin component is generally used in an amount of up to 50 parts by weight, particularly preferably in an amount of 5 to 35 parts by weight, per 100 parts by weight of the polyester.

The polyester sheet used in the present invention may contain compounding agents known per se, such as antioxidants, heat stabilizers, ultraviolet absorbers, antistatic agents, fillers, and coloring agents. it can. Although the heat-resistant container of the present invention is excellent in transparency itself, it is of course possible to make the molded container opaque. In this case, calcium carbonate, calcium silicate, alumina, silica, and various clays can be used. And fillers such as calcined gypsum, talc and magnesium, and inorganic and organic pigments such as titanium white, yellow iron oxide, red iron oxide, ultramarine and chromium oxide.

The polyester sheet used in the present invention is:
It may be composed of the above-mentioned polyester single layer, or may be composed of a laminate with another resin layer such as a gas barrier resin. As the gas barrier resin, any known resin such as an ethylene-vinyl alcohol copolymer (E
VOH), a nylon resin (Ny), a gas barrier polyester resin (BPR), a cyclic olefin copolymer, or the like. The other resin layer can be used as an inner layer or an outer layer in a two-layer configuration, or can be used as an intermediate layer in a three-layer configuration.

The gas barrier resin layer has a vinyl alcohol content of 40 to 85 mol%, particularly 50 to 8 mol%.
0 mol% ethylene-vinyl alcohol copolymer is suitable. The molecular weight of the ethylene-vinyl alcohol copolymer is not particularly limited as long as it is a molecular weight sufficient to form a film, but generally, 85% by weight of phenol and 15% of water are used.
It is preferred that the intrinsic viscosity (IV) is in the range of 0.07 to 0.17 dl / g, as measured at a temperature of 30.degree.

Other examples of the gas barrier resin include nylon resins such as nylon 6, nylon 6,6, a nylon 6 / nylon 6,6 copolymer, and a xylylene group-containing polyamide. Examples of the ω-aminocarboxylic acid component constituting the nylon resin include ε-caprolactam, aminoheptanoic acid, aminooctanoic acid, and the like, and examples of the diamine component include aliphatic diamines such as hexamethylenediamine and oils such as piperazine. Examples thereof include a cyclic diamine, m-xylylenediamine, and / or p-xylylenediamine. Examples of the dibasic acid component include aliphatic dicarboxylic acids such as adipic acid, sebacic acid, and suberic acid, and aromatic dicarboxylic acids. For example, terephthalic acid, isophthalic acid and the like can be mentioned. As a material having particularly excellent barrier properties, m-xylylene and / or p-xylylenediamine account for at least 35 mol%, particularly at least 50 mol%, of the diamine component, and the dibasic acid component as the aliphatic dicarboxylic acid and / or aromatic compound. Group dicarboxylic acids, optionally up to 25 mol%, especially 20 mol%, per total amide repeating unit
Examples of the polyamide include the following ω-aminocarboxylic acid units. The polyamide used preferably has a relative viscosity (ηrel) of 0.4 to 4.5 measured at a concentration of 1 g / 100 ml and a temperature of 25 ° C. using 96% by weight sulfuric acid.

As the gas barrier resin, a gas barrier polyester can be used. One type of the gas barrier polyester (hereinafter, sometimes referred to as BPR) is a polymer chain having a terephthalic acid component (T) and an isophthalic acid component (I) in the polymer chain: T: I = 95: 5. To 5:95, especially in a molar ratio of 75:25 to 25:75, and ethylene glycol component (E) and bis (2-hydroxyethoxy) benzene component (BHE)
B) and E: BHEB = 99.999: 0.001 to 2.0:
98.0, especially in a molar ratio of 99.95: 0.05 to 40:60. As BHEB, 1,3-bis (2-hydroxyethoxy) benzene is preferable. The polyester (BPR) should have at least a molecular weight sufficient to form a film and is generally measured in a mixed solvent of phenol and tetrachloroethane in a weight ratio of 60:40 at a temperature of 30 ° C. 0.3 to 2.8
It is desirable to have an intrinsic viscosity [η] of dl / g, particularly 0.4 to 1.8 dl / g.

The container of the present invention may contain any other resin layer in addition to the polyester resin layer and the gas barrier resin layer described above. For example, when there is no thermal adhesion between the polyester layer and the gas barrier resin layer, an adhesive resin layer can be interposed between both resin layers. The adhesive resin is not particularly limited, but an acid-modified olefin-based resin, for example, maleic anhydride-grafted polyethylene, maleic anhydride-grafted polypropylene, or the like can be used.

In FIG. 13 showing an example of a cross-sectional structure of a multilayer plastic sheet used for manufacturing the heat-resistant container of the present invention, this sheet 3 is made of an inner layer 11 and an outer layer 12 made of a thermoplastic polyester resin and a gas barrier resin. It has a laminated structure of an intermediate layer 13 and, if necessary, adhesive layers 14 and 15 provided for firmly bonding the inner and outer layers and the intermediate layer.

The laminated sheet is preferably produced by co-extruding the thermoplastic polyester resin, the gas barrier resin and, if necessary, the adhesive resin into the multilayer structure through a multilayer multiple die. It can also be manufactured by other lamination techniques such as an extrusion coating method. In a plastic sheet having a laminated structure, the thickness (tA) of the thermoplastic polyester inner and outer layers and the thickness (tB) of the oxygen barrier resin intermediate layer are as follows: tA: tB = 100: 1 to 4: 1, particularly 25: 1 to 5 : 1 is desirable. FIG. 14 shows the H / D ratio and the internal volume change rate of the container using the laminated sheet of the present invention. If the H / D is 1.3 or more, the internal volume change rate at 85 ° C. is within 4%. It turns out that it is.

In forming the sheet, the plastic sheet is heated to the above-mentioned sheet temperature (Ts). Heating of plastic sheet, infrared or far infrared heating,
It can be performed by heating with a hot blast stove, heating by heat transfer, or the like. On the other hand, the plug and the mold are maintained at the above-described plug temperature (above the crystallization temperature) and the mold temperature (below the glass transition point), and these temperature controls are performed by the heater built in the plug or the mold. This is performed by ON-OFF control of the above or by passing a heat medium for temperature control through a plug or a mold.

The plug used in the production of the heat-resistant container of the present invention preferably has a flat bottom shape in order to heat-set the entire stretch-formed container, and is connected to the tip of the body of the plug, that is, the bottom. It is preferable that the portion to be formed is a tapered portion whose diameter gradually increases upward. That is, by providing such a tapered portion, the polyester on the plug bottom can be easily pulled into the body, and a container having a good orientation distribution can be manufactured. The taper angle (α) of the tapered portion is suitably in the range of 0.5 to 10 °, particularly 2 to 6 °, and the tapered portion is formed so that the ratio of the height of the plug is 0.3 to 0.9. It is preferred to provide. Also,
The plug may have a flange step forming portion, and an oriented crystallized flange portion may be formed. Further, it is preferable that the mold is subjected to Teflon (registered trademark) coating or mirror finishing in order to prevent a stick-slip phenomenon with the sheet surface.

On the other hand, the pressure applied to the sheet being formed is preferably air pressure from the plug side.
Vacuum from the mold side may be supplementarily combined. Generally speaking, the pressure from the sheet inner surface side is 2 to 10 kg / cm.
What is necessary is just a thing which becomes ² .

(Measurement method) Differential scanning calorimeter (DSC) measurement Exothermic peak area at 100 to 175 ° C, endothermic peak area at 200 to 275 ° C when the temperature was raised from 20 ° C at a rate of 10 ° C / min using a differential scanning calorimeter. Is calculated,
The heat of crystallization ΔHc and the heat of melting endotherm ΔHm were used. 2. X-ray Diffraction Measurement Using a transmission X-ray diffractometer, X-rays are vertically incident on the container wall surface, and the Bragg angle (2
θ = 0-150 °). From the obtained diffraction profile, the plane index (010), (−11)
0), the diffraction intensity of H (010), H (-110)
And

3. Crystallinity n-heptane-carbon tetrachloride, water-calcium nitrate system 2
The density (ρ) of the sample under the condition of 20 ° C. was determined using a kind of density gradient tube. The crystallinity (Xc) was calculated from the obtained density according to the following equation. Xc = (ρc / ρ) × [(ρ−ρam) / (ρc−ρa)
m)] × 100 In the formula, ρam and ρc are the amorphous density (= 1.335 g / cm ³ ) and the crystal density (= 1.455 g / cm ³ ) of polyethylene terephthalate, respectively.

4. Thickness distribution measuring method It was measured using a ball effect thickness gauge MAGNA-MIKE Model 8000 manufactured by PANAMETRICS. 5. Heat resistance evaluation The heat resistance of the container was evaluated by the internal volume change rate (%) represented by the above-mentioned formula (1).

[0039]

EXAMPLES Example 1 An inner layer and an outer layer of polyester (J125T manufactured by Mitsui Chemicals) containing polyethylene terephthalate as a main component, an intermediate layer of MX nylon (T-600 manufactured by Toyobo) as a gas barrier layer, and A 1.2 mm thick, substantially amorphous, multi-layer sheet composed of three kinds and five layers of an ethylene-butene copolymer-based adhesive (Modic F534 manufactured by Mitsubishi Chemical Corporation) was prepared between the inner and outer layers and the intermediate layer. Next, the sheet was cut into 30 cm, and heated to a sheet temperature of 100 ° C. by a far infrared heater. Then, using a plug-assist vacuum / pressure forming machine, the sheet was clamped with a clamp mold, and an aluminum plug heated to 120 ° C. or higher than the thermal crystallization temperature by a heater mounted inside, and a heater attached to the periphery The mold is heated to 50 ° C., the inner shape of the mold is similar to the shape of the plug, and the clearance with the plug is sandwiched by a mold (female mold) of 0.5 mm and held for 2 seconds. Blowing and vacuuming from the mold side, and the container diameter D
= 66 mm, container height H = 101 mm, H / D = 1.
The polyester container of 5) was molded. At the side walls 5 mm and 45 mm above the bottom of the polyester container, the crystallinity of the inner surface and the outer surface was measured by a density gradient tube method. As a result, the inner surface is 32.0% and the outer surface is 28.8% at the side wall portion 5 mm from the bottom portion, while the inner surface is 33.2% and the outer surface is 38.2% at the side wall portion 45 mm from the bottom portion. In all cases, the crystallinity of the inner surface of the container was larger than that of the outer surface at 29.0%.
Next, the polyester container was subjected to a hot water filling test at 85 ° C., and as a result, the rate of change in internal volume was 3.4%.

(Embodiment 2) In Embodiment 1, the plug shape and the mold shape were set to H / D = 1.3, and the container diameter D =
Molding was performed in the same manner as in Example 1 except that the container was a polyester container having a container height of 68 mm and a container height H of 88 mm, and the crystallinity of the inner surface and the outer surface of the side wall was measured by a density gradient tube method. As a result, the inner surface is 31.6% and the outer surface is 19.4% at the side wall portion 5 mm from the bottom portion, while the inner surface is 35.5% and the outer surface is 45% at the side wall portion 45 mm from the bottom portion. At 33.3%, the crystallinity of the inner surface of the container was larger than the crystallinity of the outer surface in each case. Next, the polyester container was subjected to a hot water filling test at 85 ° C., and as a result, the rate of change in internal volume was 3.5%. The polyester container was transparent, and extremely good heat resistance was obtained.

(Embodiment 3) In Embodiment 1, the plug shape and the mold shape were set to H / D = 1.4, and the container diameter D =
The molding was performed in the same manner as in Example 1 except that a polyester container having a container height of 68 mm and a container height H of 95 mm was used, and the crystallinity of the inner surface and the outer surface of the side wall was measured by a density gradient tube method. As a result, the inner surface is 31.4% and the outer surface is 29.3% at the side wall portion 5 mm from the bottom portion, while the inner surface is 31.9% at the side wall portion 45 mm from the bottom portion.
%, And the outer surface was 29.7%. In each case, the crystallinity of the inner surface of the container was larger than the crystallinity of the outer surface. Then
The polyester container was subjected to a hot water filling test at 85 ° C., and as a result, the rate of change in internal volume was 3.8%, which was excellent in transparency and extremely excellent heat resistance.

(Comparative Example 1) A molding was performed in the same manner as in Example 1 except that the temperature of the heater mounted inside the aluminum plug was set to 90 ° C., which was lower than the thermal crystallization temperature. The crystallinity of the inner and outer surfaces was measured by density gradient tube method. As a result, in the side wall portion 5 mm from the bottom portion, the inner surface was 18.8% and the outer surface was 20.8%.
%, While on the side wall 45 mm from the bottom,
The inner surface was 22.5% and the outer surface was 23.8%. In each case, the crystallinity of the inner surface of the container was smaller than the crystallinity of the outer surface. Next, the polyester container was subjected to a hot water filling test at 85 ° C., and as a result, the rate of change in internal volume was 24.2%, and the heat resistance was extremely poor.

(Comparative Example 2) In Example 1, the plug shape and the mold shape were set to H / D = 1.2, and the container diameter D =
Molding was performed in the same manner as in Example 1 except that a polyester container having a container height of 68 mm and a container height H of 83 mm was used, and the crystallinity of the inner surface and the outer surface of the side wall was measured by a density gradient tube method. As a result, the inner surface is 10.8% and the outer surface is 2.6% at the side wall portion 5 mm from the bottom portion, while the inner surface is 24.9% at the side wall portion 45 mm from the bottom portion.
Although the outer surface was 13.7%, the crystallinity of the inner surface of the container was larger than the crystallinity of the outer surface in all cases, but there were sites where the crystallinity was less than 15%. Next, the polyester container was subjected to a hot water filling test at 85 ° C., and as a result, the rate of change in internal volume was 4.9%, the film was whitish, lacked transparency, and was extremely poor in heat resistance.

In the above Examples and Comparative Examples, molding was not performed using an amorphous sheet composed of a single layer of polyester resin. However, according to the Examples and Comparative Examples, even when a polyester single layer sheet was used. According to the present invention, it is easily inferred that the crystallinity of the inner surface of the container is larger than the crystallinity of the outer surface.

[0045]

According to the present invention, a polyester sheet containing polyethylene terephthalate as a main component is heated to a stretching temperature, and the polyester sheet is heated to a temperature higher than or equal to the crystallization temperature of the polyester sheet. And a mold maintained at a temperature equal to or lower than the glass transition point of the polyester sheet, by pressure-forming to efficiently and efficiently produce a container having excellent heat resistance and transparency. A possible manufacturing method could be provided. Further, the heat-resistant container obtained by the production method of the present invention is a container obtained by molding a polyester sheet containing polyethylene terephthalate as a main component, and has oriented crystals by stretching. It has a feature that the crystallinity of the inner surface of the container is larger than the crystallinity of the outer surface of the container, and has excellent heat resistance and transparency.

[Brief description of the drawings]

FIG. 1 is a diagram showing the degree of crystallinity at each part of the container of the present invention.

FIG. 2 is a diagram showing a relationship between a filling temperature and a rate of change in internal volume in the container of the present invention.

FIG. 3 is a diagram showing a neutral state in the manufacturing method of the present invention.

FIG. 4 is a view showing a clamping step in the manufacturing method of the present invention.

FIG. 5 is a view showing a stretching and heat fixing step in the production method of the present invention.

FIG. 6 is a view showing a compressed air step in the manufacturing method of the present invention.

FIG. 7 is a view showing a mold release step in the production method of the present invention.

FIG. 8 is a diagram showing the thickness of each part of the container of the present invention.

FIG. 9 is a view showing a crystallization tendency in each part of the container of the present invention.

FIG. 10 is a view showing an orientation tendency in each part of the container of the present invention.

FIG. 11 is a diagram showing the relationship between the plug temperature and the internal volume change rate in the manufacturing method of the present invention.

FIG. 12 is a diagram showing a relationship between a plug hold time and an internal volume change rate in the manufacturing method of the present invention.

FIG. 13 is a sectional view of an example of a polyester sheet used in the present invention.

FIG. 14 is a diagram showing the relationship between the H / D ratio and the rate of change in internal volume of a container using the laminated sheet of the present invention.

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[Procedure amendment]

[Submission date] June 23, 2000 (2000.6.2)
3)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0027

[Correction method] Change

[Correction contents]

The gas barrier resin layer has a vinyl alcohol content of 40 to 85 mol%, particularly 50 to 8 mol%.
0 mol% ethylene-vinyl alcohol copolymer is suitable. The molecular weight of the ethylene-vinyl alcohol copolymer is not particularly limited as long as it is a molecular weight sufficient to form a film, but generally, 85% by weight of phenol and 15% of water are used.
It is preferred that the intrinsic viscosity [η] is in the range of 0.07 to 0.17 dl / g when measured at a temperature of 30 ° C. in a mixed solvent with the weight%.

[Procedure amendment 2]

[Document name to be amended] Drawing

[Correction target item name] Fig. 9

[Correction method] Change

[Correction contents]

FIG. 9

Continued on front page F term (reference) 3E033 AA08 AA10 BA17 BA18 BB04 BB05 BB08 CA03 CA07 CA16 CA18 DA08 DD01 EA12 FA04 FA10 4F208 AR06 AR11 MA02 MB01 MC04 MH06 MK13 MK20

Claims (5)

[Claims] 1. A container obtained by molding a polyester sheet containing polyethylene terephthalate as a main component, the container having oriented crystals by stretching, and having a crystallinity of an inner surface of the container on a side wall portion of the container. A heat-resistant container characterized by having a degree of crystallinity larger than that of the outer surface of the container. 2. A polyester sheet containing polyethylene terephthalate as a main component is heated to a stretching temperature, and the polyester sheet is connected to a plug maintained at a temperature equal to or higher than the crystallization temperature of the polyester sheet. And a die maintained at a temperature equal to or lower than the glass transition point of the polyester sheet. 3. The height (H) of the container and the outer diameter (D) of the container.
3. The method for producing a heat-resistant container according to claim 2, wherein the ratio (H / D) is 1.3 or more. 4. A heat setting is performed by holding the molded polyester sheet on the plug for at least 2 seconds.
4. The method according to claim 2, further comprising performing pressure forming.
3. The method for producing a heat-resistant container according to item 1. 5. The heat-resistant container according to claim 2, wherein a clearance between an outer surface of the plug and an inner surface of the mold is in a range of １ ／ to ／ of a sheet thickness. Law.