JP2003159743A - Method for making synthetic resin vessel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for making a synthetic resin vessel capable of making a vessel in high efficiency without wasting a material and with excellent external appearance and strength. <P>SOLUTION: A molded body is subjected to compression molding and after the molded body is drawn in compliance with requirement, thermoforming, preferably plug-assist vacuum forming and/or pressure forming, is carried out. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a synthetic resin container, particularly a synthetic resin container which can be conveniently used as a container for food and drink.

[0002]

As is well known, as a container for food and drink, it has a flange, a cylindrical or polygonal side wall hanging from the inner edge of the flange, and a bottom wall closing the lower end of the side wall. A synthetic resin container in the shape of a cup or a tray whose part is inclined inward toward the bottom is widely used. Such a container is formed by first extruding a synthetic resin sheet, then heating and softening the sheet to simultaneously vacuum and / or pneumatically form multiple regions of the sheet into the required shape, and then enclosing the required shape portion. It is manufactured by cutting the portion to be cut and thus separating the required shape portion from the sheet.

JP-A-5-69478 and JP-B-7
-67737, in place of the above-mentioned manufacturing method,
It is disclosed that a sheet-shaped preform (preform) is injection-molded, and then the preform is vacuum and / or pressure-formed to produce a synthetic resin container.

[0004]

However, the conventional manufacturing method as described above, in which the sheet is first extruded, involves the following steps:
There is a problem that the remaining portion of the sheet (so-called skeleton portion) separated from the required shape portion occupies a considerable portion of the sheet, usually 40 to 60%, and the remaining portion is wastefully discarded, and therefore the material yield is extremely low. The rest of the sheet is also intended to be melted and reused, but reuse causes the material quality to deteriorate, and to avoid excessive degradation of material quality, reuse the rest of the sheet rather than the entire sheet. There is no choice but to limit it to only a part. If the sheet contains additional layers such as a gas barrier layer together with the main layer, it is practically impossible to reuse the rest of the sheet. Further, for the convenience of the manufacturing process, it is necessary that the sheet can be wound in a roll shape, and therefore the thickness of the sheet is limited to a predetermined value, for example, about 1.2 mm or less, which causes the thickness of the container to decrease. The thickness of the bottom wall, and thus the strength, tends to be too small.

Japanese Unexamined Patent Publication No. 5-69478 and Japanese Patent Publication No.
According to the manufacturing method as described above, which is disclosed in Japanese Patent Publication No. 67737, there is no problem as described above in the manufacturing method in which the sheet is first extrusion-molded. However, in such a manufacturing method, a local protrusion is inevitably generated in the pre-molded product due to the presence of the injection gate during injection molding, and the presence of such a protrusion tends to damage the appearance of the container. is there. Also, the production efficiency of the container is limited due to the relatively low injection molding efficiency. Further, in the case of injection molding, it is necessary to raise the resin temperature and the cycle time is long, so the quality of the synthetic resin material is deteriorated due to the long residence time of the resin. More specifically, in the case of polyester resin, There is also a problem that the intrinsic viscosity is considerably lowered and the acetaldehyde value is increased.
These are not desirable in that the container strength, recyclability and hygiene are deteriorated.

The present invention has been made in view of the above facts, and its main technical problem is to manufacture a container having an excellent appearance and strength with high efficiency without wastefully discarding materials. Another object of the present invention is to provide a new and improved method for producing a synthetic resin container.

[0007]

Means for Solving the Problems As a result of intensive studies by the present inventors, the above-mentioned main technical problem is obtained by compression-molding a pre-molded body, stretching the pre-molded body as necessary, and then thermoforming it. It has been found that can be achieved.
Here, thermoforming is compressed air forming along a mold with compressed air, vacuum forming along a mold by vacuum,
Vacuum pressure forming that combines vacuum forming and pressure forming, plug assist forming that performs vacuum and / or air forming while preforming the preform with an auxiliary plug or after preforming, preforming the female and male molds. Matched molding that is press-molded by sandwiching it between them, plug molding that presses the periphery of the pre-molded body and presses it with a plug to mold along the shape of the plug, and the like, and the present invention includes vacuum and / or compressed air. Molding is suitable, especially plug-assisted vacuum and / or pressure molding. The thermoforming referred to here does not include ordinary blow molding (melt blow molding, stretch blow molding, etc.).

That is, according to the present invention, as a method of manufacturing a synthetic resin container that achieves the above-mentioned main technical problems, a compression molding step of molding a synthetic resin material to form a preformed body, and the preformed body. And a thermoforming step of thermoforming to obtain a molded body.

The thermoforming is preferably vacuum and / or pneumatic forming, particularly plug-assisted vacuum and / or pneumatic forming. Preferably, a stretching step of stretching the preformed body before or at the same time as the thermoforming step, a heat setting step of heat setting the molded body simultaneously with or after the thermoforming step, and a shrinking of the molded body Back
It includes a post-process of shaping and cooling. Conveniently, the synthetic resin material comprises a polyester resin. The synthetic resin container has a flange, a cylindrical side wall that hangs from the inner edge of the flange, and a bottom wall that closes the lower end of the side wall, and at least a portion of the side wall is cup-shaped or tray-shaped that inclines downward. Good. The synthetic resin material may include a main synthetic resin and a gas barrier resin. The synthetic resin container molded in the present invention may be provided with a flange of any known form depending on the purpose. For example, the top surface may be flattened for the purpose of sealing with a heat-sealing lid, or one or a plurality of annular protrusions for protrusion sealing may be provided. Further, for the purpose of imparting rigidity to the container, it is possible to form a curled portion (skirt portion) at the tip of the flange. In addition, it may be in a form suitable for winding and tightening the metal lid.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the method for producing a synthetic resin container of the present invention will be described below with reference to the accompanying drawings.
Further details will be described.

Referring to FIGS. 1 and 2, in the preferred embodiment of the method for manufacturing a synthetic resin container according to the present invention, first, the compression molding apparatus 2 is used to perform the compression molding process. The illustrated compression molding apparatus 2 includes a stationary lower mold member 4
And a movable upper mold member 6. As shown in FIG. 1, the upper mold member 6 is positioned in the open position, that is, the raised position with respect to the lower mold member 4, and the lower mold member 4 is moved.
A synthetic resin material 8 in a softened or melted state is supplied on top. Next, the lower mold member 6 is lowered to the closed position shown in FIG. 2, and thus the preform 10 is compression-molded from the synthetic resin material 8. The preformed body 10 in the illustrated embodiment includes an annular flange 12, a side wall 14 hanging from an inner peripheral edge of the flange 12, and a circular bottom wall 16 closing a lower end of the side wall 14.
Have. The side wall 14 is in the shape of an inverted truncated cone that extends inwardly downward and has a relatively small height.

In the synthetic resin container manufacturing method of the present invention, an appropriate thermoplastic resin can be used as the synthetic resin material. Examples of the thermoplastic resin include, but are not limited to, polyester resins, polyolefin resins, polystyrene resins, polyamide resins, and polycarbonate resins.

As the polyolefin resin, for example,
Low-medium-high density polyethylene, isotactic polypropylene, syndiotactic polypropylene, propylene-ethylene copolymer, ethylene-vinyl acetate copolymer, olefin resin graft-modified with ethylenically unsaturated carboxylic acid or its anhydride And so on.
The polyester resin is mainly composed of an aromatic dicarboxylic acid component and a glycol component. Examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, P-β-oxyethoxybenzoic acid, biphenyl-4,4'-dicarboxylic acid, diphenoxyethane-4,4'-dicarboxylic acid, 5- Sodium sulfoisophthalic acid, hexahydroterephthalic acid,
Examples thereof include adipic acid, sebacic acid, trimellitic acid, pyromellitic acid and the like. As the glycol, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 1,4-butanediol, neopentyl glycol, 1,3- or 1,4-cyclohexanedimethanol, 1,6-hexylene glycol, glycerol, Examples thereof include trimethylolpropane, pentaerythritol, dipentaerythritol, sorbitan, bisphenol A, an ethylene oxide adduct of bisphenol A, and bisphenol S. As other polyester resins, polylactic acid and copolymers of lactic acid and other components can also be used. As polylactic acid, in order to promote oriented crystallization and obtain high heat resistance and heat fixing (heat setting) effect, the melting point is 160 to
L-lactic acid at 200 ° C. is 4% or less, more preferably 2.5.
% Or less of the resin is preferable. The heat setting temperature of polylactic acid is 70 to 150 ° C, preferably 80 to 120 ° C. The melting point (Tm), the glass transition temperature (Tg), the temperature rising crystallization peak temperature (Tc), and the temperature rising crystallization start temperature (Tic) used in the present text are arbitrarily selected from the compact to be measured. Differential scanning calorimeter (DS)
C), hold at 300 ° C. for 3 minutes in a nitrogen gas atmosphere, then rapidly cool to room temperature, heating rate 20 ° C./min.
It is based on the value obtained from the DSC curve obtained by heating at.

In the method for producing a synthetic resin container of the present invention, various polyester resins can be preferably used, but particularly excellent transparency and impact resistance can be obtained by stretching and heat setting is effective. A polyester resin that acts is desirable, and a polyester mainly composed of polyethylene terephthalate, polypropylene terephthalate, and polylactic acid having a glass transition temperature of room temperature or higher and having crystallinity can be particularly preferably used. Economics,
From the viewpoint of moldability and physical properties of molded products, polyethylene terephthalate in which the ethylene terephthalate unit accounts for 80 mol% or more, particularly 90 mol% or more is preferable. As a copolymerization component when such polyethylene terephthalate is used, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 1,4-butanediol, 1,4-cyclohexanedimethanol and the like are preferable. Polyethylene terephthalate is most suitable as the thermoplastic polyester resin, but the thermoplastic polyester resin is not limited to this, and polyethylene / butylene terephthalate, polyethylene terephthalate /
2,6-naphthalate, polyethylene terephthalate /
Isophthalate, and polybutylene terephthalate, polybutylene terephthalate / isophthalate, polyethylene-2,6-naphthalate, polybutylene terephthalate / adipate, polyethylene-2,6-naphthalate / isophthalate, polybutylene terephthalate / adipate, or these. It is also possible to use a blended product of two or more of the above. Polyester is an intrinsic viscosity [IV] measured using a phenol / tetrachloroethane mixed solvent as a solvent in terms of moldability of a preform, moldability in container molding, mechanical properties of a container and heat resistance.
Is preferably 0.5 or more, and particularly preferably in the range of 0.6 to 1.5. For polyester, as a modified resin component,
At least one kind of ethylene polymer, thermoplastic elastomer, polyarylate, polycarbonate and the like can be blended. The modifying resin component is generally used in an amount of up to 60 parts by weight, particularly preferably 3 to 20 parts by weight, per 100 parts by weight of polyester.

Examples of the polycarbonate resin include carbonic acid ester resins derived from bicyclic dihydric phenols and phosgene. Bisphenols such as, for example,
From 2,2'-bis (4-hydroxyphenyl) propane (bisphenol A), 2,2'-bis (4-hydroxyphenyl) butane (bisphenol B), 1,2-bis (4-hydroxyphenyl) ethane, etc. Derived polycarbonate is preferred.

The synthetic resin used in the method for producing a synthetic resin container according to the present invention includes the compounding agents known per se, such as an antioxidant, a heat stabilizer, an ultraviolet absorber, an antistatic agent, a filler, a lubricant and an inorganic material. An organic or organic colorant may be added.

Continuing the description with reference to FIG. 3, the pre-molded body 10 taken out from the compression molding apparatus 2 is heated and softened, and then the plug-assisted vacuum and pressure molding apparatus 1 is used.
8 are supplied. The heating temperature of the preform 10 at this time is generally higher than the glass transition temperature (Tg) of the main synthetic resin,
It is preferably in the range of melting point (Tm) + 50 ° C. or lower. Particularly, for example, when the pre-molded body 10 is obtained in a substantially amorphous state like a polyester resin, a temperature of Tg or more and a crystallization peak temperature (Tc) or less is preferable, and Tg + 5 to T
The range of c-10 ° C is more preferable. If it is less than Tg, not only a large molding pressure is required, but also the molding itself becomes difficult, which is not preferable. On the other hand, Tc
If it exceeds, the spherulites are formed, the transparency is impaired, and the molding becomes difficult, which is not preferable.
In addition, for example, a pre-molded body 1 such as polypropylene resin
When 0 is obtained in a substantially crystallized state, Tm
± 50 ° C. is preferable, and Tm ± 30 ° C. is more preferable.
The pre-molded body 10 does not necessarily need to be uniformly heated as a whole, and may be formed according to a place to be processed and a degree of processing.
The heating can be performed using a known method such as heating with an infrared heater. Continuing with the description with reference to FIG. 3, the illustrated plug-assisted vacuum and pneumatic forming apparatus 18 includes a stationary mold member 20, a clamping member 22 and a plug member 24. The mold member 20 is formed with a molding cavity 26 extending downward from the upper surface thereof. The molding cavity 26 may have an inverted truncated cone shape whose inner diameter gradually decreases downward. The mold member 20 is further formed with a communication hole 28 extending from the lower end surface thereof to the molding cavity 26. The tightening member 22 has an annular shape as a whole, and the inner diameter of the opening located at the center thereof is made substantially the same as the inner diameter of the upper end of the molding cavity 26 formed in the mold member 20. Plug member 24
Has a plug portion 30 having an inverted truncated cone shape whose outer diameter gradually decreases downward. A shallow circular recess 32 is formed on the lower surface of the plug portion 30. The plug member 24 includes
Further, a communication hole 34 extending to the circular recess 32 is formed. The preform 10 is placed on the mold member 20 with the tightening member 22 in the raised position shown by the solid line in FIG. The flange 12 of the preform 10 is the mold member 20.
Located on the upper surface of the side wall 14 and the bottom wall 16 of the molding cavity 2
Immersed in 6. Then, the tightening member 22 is lowered to the position shown by the chain double-dashed line in FIG.
0 between the upper surface of 0 and the lower surface of the tightening member 22.
The flange 12 is clamped.

Next, the plug member 24 is gradually lowered and the drawing process is performed. As can be understood by comparing and referring to FIGS. 3 and 4, when the plug member 24 is gradually lowered, the side wall 14 and the bottom wall 16 of the preform 10 are gradually stretched accordingly. Further, the communication hole 28 of the mold member 20 is communicated with a vacuum source (not shown), and the communication hole 34 of the plug member 24 is also communicated with a compressed air source (not shown), so that a vacuum is generated by vacuum suction. Pressure molding by compressed air pressure is performed together with molding, and the pre-molded body 10 is made into a molded body 36 having a shape corresponding to the inner surface of the molding cavity 26 formed in the mold member 20. In the illustrated embodiment, the communication hole 28 of the mold member 20 is connected to a vacuum source for vacuum forming, and the communication hole 34 of the plug member 24 is connected to a compressed air source for pressure forming. If desired, only one of vacuum forming and pressure forming can be performed.
The vacuum and / or pneumatic forming may be started at the same time when the lowering of the plug member 24 is started, during the lowering of the plug member 24, or at any time after the lowering of the plug member 24 is finished. At this time, the temperature of the plug member 24 can be arbitrarily set as long as it does not affect the quality of the molded body. For example, when the pre-molded body 10 is made of a polyester resin, it is preferable that the temperature ranges from near room temperature to the heating temperature (To) of the pre-molded body 10 + 50 ° C. When this is cooled from room temperature, dew condensation may occur on the surface of the plug member 24,
Further, if it exceeds To + 50 ° C., the pre-molded body 10 may be partially heated and stretched too much.
Continuing with the description, the molded body 36 may be taken out as a final molded product at this point. In this case, the mold member 20 only needs to have a temperature at which the molded body 36 can be taken out, and is not limited to this temperature in general, but 10 ° C or higher and 70 ° C or higher.
The following is good. The stretch ratio of each part of the molded body 36 is a ratio to / t ₁ of the wall thickness to before processing and the wall thickness t ₁ after processing (corresponding to the area stretching ratio when the change in the specific gravity before and after molding is small. Is preferably 1.5 or more from the viewpoint of imparting impact resistance and transparency.

In the illustrated embodiment, the mold member 20 is heated by a suitable heating means (not shown) such as an electric resistance heater during the above-described vacuum and / or pressure forming, and the molding cavity 26 is formed. The inner surface of the is heated to a high temperature of, for example, about 180 ° C. Accordingly, the vacuum and / or pressure-formed molded body 36 is heated and heat set by being brought into contact with the mold member 26 substantially simultaneously with vacuum and / or pressure-formed. Such a heat setting step may be performed after vacuum and / or pneumatic forming, if desired, so that heating of the mold member 20 is started after vacuum and / or pneumatic forming. The heat setting temperature is preferably the glass transition temperature Tg or higher and the melting point Tm or lower of the main synthetic resin, and more preferably the temperature rising crystallization start temperature Tic or higher and Tm-10 ° C or lower. If the heat setting temperature is lower than Tg, sufficient heat setting cannot be obtained, and if the heat setting temperature exceeds Tm, the molded body 36 is welded to the mold member 20 and the heat setting effect cannot be obtained, which is not preferable. As for the draw ratio of the molded body 36 in the case of heat setting, the ratio to / t ₁ of the wall thickness to before processing and the wall thickness t ₁ after processing is preferably 2 or more, and 3 to ₁
The range of 2 is more preferable. If it is less than 2, the stretching is insufficient, so that spherulites are likely to occur and impact resistance and transparency are deteriorated, which is not preferable. Further, if it exceeds 12, oriented crystallization becomes too strong, and when shrink-back molding described later is carried out, shrink-back becomes insufficient and the molded product tends to be insufficiently shaped, which is preferable. Absent.

After the vacuum and / or pressure forming step and the heat setting step, a post-step of shrink-back, shaping and cooling is performed. In the subsequent step, as shown in FIG. 5, the communication hole 28 of the mold member 20 is connected to the compressed air source, and the communication hole 34 of the plug member 24 is connected to the vacuum source. Therefore, the molded body 36 is shrink-backed into a shape corresponding to the plug portion 30 of the plug member 24 by vacuum suction and compressed air pressurization, and is shaped into the final shape, that is, the container 38. The amount to be shrunk back is determined by the inner size of the mold member 20 and the size of the plug portion 30 of the plug member 24. The smaller the difference between these sizes, the wider the range of molding conditions, which is preferable. Generally, the plug portion 30
It is advisable to set the dimension of 90% or more to almost the same dimension as the inner dimension of the mold member 20 (matched molding). Further, a male mold different from the plug member 24 can be used for shaping the final shape. After the shrink back, the final molded product, that is, the container 38 is cooled, the tightening member 22 is raised, and the container 38 is taken out. Container 3 molded in this way
As shown in FIG. 5, 8 is an annular flange 40, a side wall 42 that hangs from the inner edge of the flange 40, and a side wall 42.
And a bottom wall 44 that closes the lower end of the. The side wall 42 has a truncated cone shape in which the outer diameter is gradually reduced downward (and thus is inclined inward downward).
A circular recess 46 corresponding to the circular recess 32 formed on the bottom surface of the plug member 24 is formed at the center of the bottom wall 44. Illustrated container 38 whose side wall 42 is frustoconical
Can be taken out from the mold member 20 by simply pulling it upward without forming the mold member 20 into a so-called split mold structure. In the illustrated container 38, the side wall 42 is slanted inward downward from the upper end to the lower end thereof, but as shown by the chain double-dashed line in FIG. The ridge portion 46 inclined outward
It is also possible to prevent the adjacent flanges 40 from coming into close contact with each other when a plurality of containers 38 are stacked to make it difficult to separate the containers 38, and in this case as well, when the protrusion 46 is relatively small. The container 38 can be removed from the mold member 20 by simply pulling it upwards.

6 to 10 illustrate respective steps in another embodiment of the synthetic resin container manufacturing method of the present invention.
In the embodiment shown in FIGS. 6 to 10, the synthetic resin material 108 supplied to the compression molding apparatus 102 includes a main synthetic resin layer 109 and an additional synthetic resin layer 111 enclosed in the main synthetic resin layer 109. It consists of The synthetic resin forming the main synthetic resin layer 109 may be the same as the synthetic resin forming the synthetic resin material 8 shown in FIG. On the other hand, the synthetic resin that constitutes the additional synthetic resin layer is preferably a synthetic resin such as a gas barrier resin, a recycled resin, an oxygen absorbing resin, or a moisture resistant resin.

The gas barrier resin is any known resin, for example, the oxygen barrier resin is ethylene-
Vinyl alcohol copolymer (EVOH), nylon resin (Ny), gas barrier polyester resin (BPR)
Further, a cyclic olefin-based copolymer (COC) or the like can be used as the water vapor barrier resin. The ethylene-vinyl alcohol copolymer has a vinyl alcohol content of 40 to 85 mol%, particularly 50 to 80 mol%.
A mol% ethylene-vinyl alcohol copolymer is suitable. Examples of the nylon resin include nylon 6, nylon 6,6, nylon 6 / nylon 6,6 copolymer, and xylylene group-containing polyamide. Examples of the ω-aminocarboxylic acid component constituting the nylon resin include ε-caprolactam, aminoheptanoic acid, aminooctanoic acid, etc., and examples of the diamine component include aliphatic diamines such as hexamethylenediamine and fats such as piperazine. Examples thereof include cyclic diamine, m-xylylenediamine and / or p-xylylenediamine. As dibasic acid components, aliphatic dicarboxylic acids such as adipic acid, sebacic acid and suberic acid, aromatic dicarboxylic acids,
Examples thereof include terephthalic acid and isophthalic acid. Especially, as a material having excellent barrier properties, 35 of diamine component is used.
Mol% or more, particularly 50 mol% or more is m-xylylene and / or p-xylylenediamine, the dibasic acid component is an aliphatic dicarboxylic acid and / or aromatic dicarboxylic acid, and, if desired, per all amide repeating units Polyamides containing 25 mol% or less, especially 20 mol% or less ω-aminocarboxylic acid units are mentioned. As the gas barrier resin, a gas barrier polyester can also be used. One type of this gas barrier polyester has a terephthalic acid component and an isophthalic acid component in the polymer chain.
5: 5 to 5:95, particularly 75:25 to 25:75 in a molar ratio and containing an ethylene glycol component and a bis (2-hydroxyethoxy) benzene component in 99.
99: 0.01 to 2:98, especially 99.95: 0.0
It is preferably contained in a molar ratio of 5 to 40:60.

Examples of the recycled resin include recycled polyester. The polyester resin obtained by collecting the used polyester container preferably has an intrinsic viscosity (IV) in the range of 0.5 to 1.0. The recycled resin can be used alone or in a blend with the virgin resin.

The oxygen-absorbing resin contains a metal-based oxidation catalyst and an oxidizing resin or an oxidizing organic component,
Those containing polyphenols, ascorbic acids, etc. and a basic substance are used. The oxidizing resin or the oxidizing organic component is a resin or an organic component that is oxidized by oxygen in the air due to the action of the transition metal catalyst. As the oxidizable resin, (1) a resin having a tertiary carbon such as polypropylene, (2) a resin having a carbonyl group such as an ethylene-carbon monoxide copolymer,
(3) Polyamide resin having a benzene ring such as MXD6, (4) Resin having an unsaturated double bond in the main chain such as polybutadiene, polyisoprene and copolymers thereof, (5) Cyclohexene group, etc. A resin having an unsaturated double bond in the side chain is used. Examples of the oxidizing organic component include (6) ascorbic acids and (7) cystine, which absorb water and oxygen in the presence of a basic substance such as sodium carbonate and potassium acetate. As the metal-based oxidation catalyst, metal compounds of Group VIII of the periodic table such as iron, cobalt and nickel are preferable, but in addition, copper, silver and the like (Group I), tin, titanium, zirconium and the like (Group IV). ), Vanadium (group V), chromium (group VI), manganese (group VII), and the like. Among these metal compounds, the cobalt compound has a large oxygen absorption rate and is particularly preferable. The transition metal-based catalyst is generally used in the form of an inorganic acid salt, an organic acid salt or a complex salt of the above transition metal having a low valence.
These catalysts are 100 to 2 in terms of metal amount per resin.
It is recommended to use it in an amount of 000 ppm.

Further, an optional resin layer may be contained in the synthetic resin material if necessary. For example, when the thermoplastic resin layer and the gas barrier resin layer do not have adhesiveness, an adhesive resin layer can be interposed between these layers. The adhesive resin is not particularly limited, but an acid-modified olefin resin such as maleic anhydride grafted polyethylene or maleic anhydride grafted polypropylene can be used.

In the embodiment shown in FIGS. 6 to 10, the pre-molded body 110 to be molded in the compression molding process.
Is composed of an annular flange 112 and a concave main portion 113 extending downward from the inner peripheral edge of the flange 112. As will be understood by referring to FIG. 7, the concave main portion 113 has a thickness gradually increasing toward the lower end and the radial center. The inner peripheral surface of the molding cavity 126 formed in the mold member 120 in the plug-assisted vacuum and compressed air molding apparatus 118 has a truncated cone shape whose upper portion has an inner diameter gradually increasing downward, and whose middle portion or lower portion is It has a cylindrical shape. Except for the points described above in the embodiment illustrated in FIGS. 6 to 10, the embodiment is substantially the same as the embodiment illustrated in FIGS. 1 to 5, and therefore the description thereof will be omitted.

11 to 16 show another embodiment of the synthetic resin container manufacturing method of the present invention. This embodiment described below imparts impact resistance, transparency and heat resistance because the amount of processing in the vacuum and / or compressed air molding step is relatively small, such as molding of a shallow cup-shaped container or tray-shaped container. If it is difficult to do so, the problem can be solved by including a stretching step in advance. In the embodiment illustrated in FIGS. 11 to 16, the pre-molded body 210 molded in the compression molding device 202 has a rectangular plate shape. The pre-molded body 210 is used in the compression molding device 202.
After being taken out from the resin, it is heated to the glass transition temperature Tg or higher and the melting point Tm or lower of the main synthetic resin to be softened and stretched as described above. Such stretching is shown in FIG.
As shown in FIG. 5, the peripheral edge portion of the pre-molded body 210 is gripped by a plurality of movable gripping means 211, and the movable gripping means 211 are gripped.
Is moved from the position shown by the solid line in FIG. 13 to the position shown by the chain double-dashed line, and thus the preform 210 is stretched to the stretched body 213 having an increased plane area. Stretching is to thickness before processing
It is preferable that the ratio to / t _{1 of the} processed thickness t ₁ is 1.5 or more and 9 or less, and particularly preferably 1.5 or more and 6 or less. If this wall thickness ratio is less than 1.5, the amount of processing in each part of the final container may be insufficient, and if it exceeds 9, stretch oriented crystallization proceeds, and the vacuum and / or pressure forming step after this stretching step may occur. Processing becomes difficult. The stretching method is not limited to the method described above, and any known method can be applied.

Thereafter, the stretched body 213 is supplied to the plug-assisted vacuum and pressure forming apparatus 218. The illustrated plug assist vacuum and pressure forming apparatus 218 includes a stationary mold member 220, a clamping member 222 and a plug member 224. The mold member 220 is formed with a relatively shallow molding cavity 226 extending downward from the upper surface thereof. The molding cavity 226 has an inverted quadrangular pyramid shape in which four side surfaces are inclined inwardly downward. The mold member 220 is formed with two communication holes 228 extending from the lower end surface to the molding cavity 226. The tightening member 222 has a rectangular frame shape as a whole, and the central opening located at the center of the tightening member 222 is substantially the same as the upper end of the molding cavity 226 formed in the mold member 220. The plug member 224 has a plug portion 230 having an inverted quadrangular pyramid shape in which four side surfaces are inclined inwardly downward. A shallow rectangular recess 232 is formed on the lower surface of the plug portion 230. Plug member 224
In addition, the two communication holes 2 extending to the rectangular recess 232.
34 is formed. With the tightening member 222 in the raised position shown by the solid line in FIG.
The stretched body 213 is placed on the top. Next, the tightening member 222 is moved down to the position shown by the chain double-dashed line in FIG. 14, and the peripheral portion of the stretched body 213 is sandwiched between the upper surface of the mold member 220 and the lower surface of the tightening member 222.

Next, the plug member 224 is gradually lowered, and further stretching is applied to the central main portion of the stretched body 213. In addition, the communication hole 228 of the mold member 220 is connected to a vacuum source (not shown), and also the plug member 22.
4 communicating with a compressed air source (not shown), and therefore vacuum forming by vacuum suction and pressure forming by compressed air pressurization are performed, and as shown clearly in FIG. The molded body 236 has a shape corresponding to the inner surface of the molding cavity 226 formed in the mold member 220. Also in the illustrated embodiment, the mold member 22
No. 0 communication hole 228 is connected to a vacuum source to perform vacuum forming, and communication hole 234 of the plug member 224 is connected to a compressed air source to perform pressure forming, but if desired, vacuum forming and pressure forming are performed. It is also possible to carry out either one of and. The vacuum and / or pneumatic forming may be started at the same time when the lowering of the plug member 224 is started, at any time during the lowering of the plug member 224 or after the lowering of the plug member 224 is completed.

During the above-described vacuum and / or pneumatic forming, the mold member 220 is heated by an appropriate heating means (not shown) such as an electric resistance heater to form the molding cavity 226.
The inner surface of the glass is above the glass transition temperature Tg of the main synthetic resin and the melting point Tm
The following high temperatures can be used. Thus, the vacuum- and / or pressure-formed compact 236 is heated and heat-set by being brought into contact with the mold member 220 substantially simultaneously with vacuum and / or pressure-formed. Such a heat setting step may be performed after vacuum and / or pneumatic forming, if desired, thus heating of the mold member 220 may be started after vacuum and / or pneumatic forming.

After the vacuum and / or pressure forming step and the heat setting step, a post-step of shrink-back, shaping and cooling is performed. In such a post-process, as shown in FIG. 16, the communication hole 228 of the mold member 220 is connected to the compressed air source, and the communication hole 234 of the plug member 224 is connected.
Is connected to the vacuum source. Therefore, the molded body 236 is shrink-backed into a shape corresponding to the plug portion 230 of the plug member 224 by vacuum suction and compressed air pressurization,
The final shape or container 238 is shaped. Then, the container 238 is cooled, the fastening member 222 is raised, and the container 238 is taken out. Container 38 molded in this way
As shown in FIG. 16, is a tray shape having a rectangular flange 240, a side wall 242 hanging from the inner edge of the flange 240, and a bottom wall 244 closing the lower end of the side wall 242. The side wall 242 has a truncated pyramid shape in which four side surfaces extend downward and incline. A rectangular recess 246 corresponding to the rectangular recess 232 formed on the bottom surface of the plug member 224 is formed at the center of the bottom wall 244. The illustrated container 238 whose side wall 242 has a quadrangular pyramid shape can also be taken out from the mold member 220 by simply pulling it upward without forming the mold member 220 into a so-called split mold structure. After removing the container 238 from the mold member 220,
If necessary, the rectangular flange 240 of the container 238 can be trimmed downward to finish the outer edge of the rectangular flange 240 into a desired shape. The configuration may be the same as the embodiment shown in FIGS. 1 to 5 except for the above-described configuration in the embodiment shown in FIGS. 11 to 16.

[0032]

The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

[0033]

Example 1 A polyethylene terephthalate resin having an intrinsic viscosity of 0.8 d1 / g (SA135, Mitsui Chemicals, Inc., containing 2 mol% of isophthalic acid) was supplied to an extruder, and a die temperature of 27 was used.
It was extruded into a cylindrical shape and cut under the condition of 0 ° C. The obtained resin block is set in the molten state in the center of the lower mold member 4 of the compression molding apparatus 2 as in FIG. 1, and the mold clamping pressure is 120 kgf /
By compression molding at cm ² , a single layer of substantially non-crystalline preform (preform) 10 was obtained. The weight of the obtained preform was 13 g.

After heating this preform to 90 ° C. above the glass transition temperature and setting it on the mold member 20 of the plug-assisted vacuum and compressed air forming apparatus 18 as in FIG. 3, and holding the flange portion with the tightening member 22. , Plug assist and vacuum pressure molding. At this time, the mold member 20 is set to 30
℃, plug member 24 60 ℃, tightening member 22 30 ℃
And In this way, a transparent cup-shaped container with a flange was obtained by cooling with a mold member similar to that shown in FIG. The container dimensions are: flange outer diameter 75 mm, inner diameter 64 mm, bottom outer diameter 4
It had a size of 8 mm and a height of 85 mm, and the full-volume content was 210 cc.

[0035]

Example 2 Mold member 20 was set to 180 ° C., plug member 24 was set to 90 ° C., vacuum assisted vacuum molding was performed with plug assist, and the molded body was heat set for 2 seconds along the mold member 20 and then shrink-backed. Then, a cup-shaped container with a flange was obtained in the same manner as in Example 1 except that the container was placed along the plug member 24, shaped, and cooled.

[0036]

Example 3 A polymeta-xylylene adipate, which is a double-layered die and continuously extrudes the polyethylene terephthalate resin, which is the main synthetic resin forming the outer surface side, and a gaz barrier layer, which forms the inner core side. Mid resin (MXD6 manufactured by Mitsubishi Gas Chemical Co., Inc.) was extruded intermittently, and this composite melt extrudate was cut to obtain a columnar molten resin mass. The cutting timing was the same as in Example 2 except that the MXD6 was located almost at the center of the molten resin mass and the molten resin mass enclosed in the main synthetic resin on the outer surface side was compression molded.
The inner and outer layers are polyethylene terephthalate resin, and the middle layer is M
A cup-shaped container with a flange of XD6 was obtained. The gas barrier layer was 5% by weight of the whole.

[0037]

Example 4 A cup-shaped container with a flange was obtained in the same manner as in Example 3 except that the resin on the inner core side was a recycled resin of polyethylene terephthalate. The recycled resin is 25
It was set to% by weight.

[0038]

Example 5 The cup-shaped container obtained in Example 1
After shrinking under an atmosphere of ℃, it was set on another mold member (not shown) at 180 ℃, vacuum pressure again, and heat set for 2 seconds. Further, another plug member (not shown) at 90 ° C. was inserted, and this was shrink-backed and cooled to give a transparent cup-shaped container with a flange. In addition, the container dimensions are 75 mm flange outer diameter,
Same inner diameter 64mm, bottom outer diameter 54mm, height 51mm,
It was a full capacity 14 cc.

[0039]

Example 6 A polyethylene terephthalate resin (J125T, manufactured by Mitsui Chemicals, Inc.) having an intrinsic viscosity of 0.74 d1 / g was supplied to an extruder and extruded and cut under a die temperature of 270 ° C. The obtained resin block is kept in a molten state and the compression molding device 2 is used.
Set in the center of the lower mold member 4 of
Compression molding was performed at kgf / cm ² to obtain a single-layer disc-shaped preform. The weight of the obtained preform was 18 g.

This preform is heated to 100 ° C. which is higher than the glass transition temperature, and the end portion is grasped by a grasping means 211 (in FIG. 13, it is stretched in four directions, but in this embodiment, it is stretched in the circumferential direction). Grasping and radially halving the thickness, that is, stretching at an area stretching ratio of 2 times, setting it in the mold member 220 at 160 ° C. while holding it, and holding the flange portion by the clamping member 222 at 60 ° C. Molded. Further, after heat-setting for 3 seconds with this mold member 220, a male mold at 90 ° C. inserted in the mold member 220 was shrink-backed and cooled, and the periphery was trimmed to obtain a transparent tray-shaped container. . In addition, the container dimensions are flange outer diameter 130 mm,
Same inner diameter 120 mm, bottom outer diameter 100 mm, height 30 m
m, and the content capacity of Manchuria was 280 cc. In addition, the loss rate of the material is 14% in the unnecessary part that trimmed the periphery,
Compared with the loss rate of 50% or more in the conventional molding method in which the sheet is thermoformed, it is 1/3 or less, and the loss rate is significantly improved.

Heat resistance was evaluated by filling hot water of 90 ° C. in the containers of Examples 2 to 6 which had been subjected to the shrinking step to impart heat resistance, but no apparent deformation was observed in any of the samples. It was In addition, the change in the full-volume content before and after this test was measured to evaluate the volumetric shrinkage rate, but all were at a level of 1% or less, which was not a problem. In addition, about 8 minutes of water in the full content was put and boiled in a microwave oven, but similar results were obtained, and sufficient heat resistance was recognized. Table 1 shows these evaluation results and the loss rate of the material.

[0042]

[Table 1]

[0043]

According to the method for manufacturing a synthetic resin container of the present invention, a container having excellent appearance, strength, heat resistance and gas barrier property can be manufactured with high efficiency without wasting materials. it can.

[Brief description of drawings]

FIG. 1 is a simplified cross-sectional view showing a starting step of a compression step in a preferred embodiment of the method for manufacturing a synthetic resin container of the present invention.

FIG. 2 is a simplified cross-sectional view showing the final stage of the compression step in the preferred embodiment of the method for manufacturing a synthetic resin container of the present invention.

FIG. 3 is a schematic cross-sectional view showing a starting step of a stretching step and a vacuum and pressure forming step in a preferred embodiment of the method for producing a synthetic resin container of the present invention.

FIG. 4 is a simplified cross-sectional view showing the final steps of the stretching step and the vacuum and pressure forming steps in the preferred embodiment of the method for producing a synthetic resin container of the present invention.

FIG. 5 is a simplified cross-sectional view showing a final stage of a post-process in a preferred embodiment of the synthetic resin container manufacturing method of the present invention.

FIG. 6 is a simplified cross-sectional view showing a starting step of a compression step in another embodiment of the synthetic resin container manufacturing method of the present invention.

FIG. 7 is a simplified cross-sectional view showing the final stage of the compression step in another embodiment of the synthetic resin container manufacturing method of the present invention.

FIG. 8 is a simplified cross-sectional view showing a starting step of a stretching step and a vacuum and pressure forming step in another embodiment of the synthetic resin container manufacturing method of the present invention.

FIG. 9 is a schematic cross-sectional view showing the final steps of the stretching step and the vacuum and pressure forming steps in another embodiment of the synthetic resin container manufacturing method of the present invention.

FIG. 10 is a simplified cross-sectional view showing a final stage of a post-process in another embodiment of the synthetic resin container manufacturing method of the present invention.

FIG. 11 is a simplified cross-sectional view showing a starting step of a compression step in still another embodiment of the method for manufacturing a synthetic resin container of the present invention.

FIG. 12 is a simplified cross-sectional view showing the final stage of the compression step in still another embodiment of the method for manufacturing a synthetic resin container of the present invention.

FIG. 13 is a simplified cross-sectional view showing a stretching step in still another embodiment of the method for manufacturing a synthetic resin container of the present invention.

FIG. 14 is a simplified cross-sectional view showing a starting stage of an additional stretching step and a vacuum and pressure forming step in another embodiment of the synthetic resin container manufacturing method of the present invention.

FIG. 15 is a simplified cross-sectional view showing the final stages of the additional stretching step and the vacuum and pressure forming step in still another embodiment of the method for producing a synthetic resin container of the present invention.

FIG. 16 is a simplified cross-sectional view showing the final stage of a post-process in still another embodiment of the method for manufacturing a synthetic resin container according to the present invention.

[Explanation of symbols]

2: Compression molding equipment 4: Lower mold member 6: Upper mold member 8: Synthetic resin material 10: Pre-molded body 18: Plug-assisted vacuum and pneumatic molding equipment 20: Mold member 22: Tightening member 24: Plug member 26: Molding cavity 36: molded body 38: Container 40: Flange of container 42: Side wall of container 44: Bottom wall of container 108: Synthetic resin material 110: Pre-molded body 118: Plug-assisted vacuum and air pressure molding device 120: Mold member 126: Molding cavity 202: Compression molding device 210: Pre-molded body 213: Stretched body 218: Plug Assist Vacuum and Pneumatic Forming Equipment 220: Mold member 222: Tightening member 224: Plug member 226: Mold cavity 236: molded body 238: Container 240: Flange of container 242: Side wall of container 244: Bottom wall of container

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[Procedure amendment]

[Submission date] December 5, 2001 (2001.12.
5)

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 5

[Correction method] Change

[Correction content]

[Figure 5]

Continued front page    (72) Inventor Makoto Eto             22-4 Okazawa-machi, Hodogaya-ku, Yokohama-shi, Kanagawa F-term (reference) 4F208 AA24 AG07 AG24 AH55 AH56                       AH58 MA01 MA02 MA03 MA05                       MA06 MB01 MC03 MC04 MG01                       MG24 MH06 MH09 MK15

Claims (9)

[Claims] 1. A synthetic method comprising: a compression molding step of compression molding a synthetic resin material to form a pre-molded body; and a thermoforming step of thermo-molding the pre-molded body to obtain a molded body. A method for manufacturing a resin container. 2. The method for producing a synthetic resin container according to claim 1, wherein the thermoforming is vacuum and / or pressure forming. 3. The method for producing a synthetic resin container according to claim 2, wherein the vacuum and / or pneumatic molding is plug-assisted vacuum and / or pneumatic molding. 4. The method for producing a synthetic resin container according to claim 1, further comprising a stretching step of stretching the preformed body before or at the same time as the thermoforming step. 5. The method for producing a synthetic resin container according to claim 1, further comprising a heat setting step of heat setting the molded body simultaneously with or after the thermoforming step. 6. The method for producing a synthetic resin container according to claim 1, further comprising a post-process of shrink-backing, shaping and cooling the molded body. 7. The method for producing a synthetic resin container according to claim 1, wherein the synthetic resin material is a polyester resin. 8. A synthetic resin container has a flange, a cylindrical side wall hanging from an inner edge of the flange, and a bottom wall closing a lower end of the side wall, and at least a part of the side wall is inclined inward toward a lower side. The method for producing a synthetic resin container according to any one of claims 1 to 7, which is in the form of a cup or a tray. 9. The method for producing a synthetic resin container according to claim 1, wherein the synthetic resin material contains a main synthetic resin and a gas barrier resin.