JP4725886B2 - Synthetic resin cup-shaped container - Google Patents

Description

The present invention relates to a cup-shaped container made of a synthetic resin in which a flange is thermally crystallized.

  A container such as a so-called PET bottle obtained by biaxially stretching blow-molding a polyethylene terephthalate (hereinafter referred to as PET) resin has mechanical strength, heat resistance, transparency, barrier properties, hygiene, etc. It is excellent and widely used in food containers such as beverages.

  And besides PET bottles, taking advantage of the excellent properties as described above, fruit juice, coffee, milk beverages, etc. for applications requiring high temperature filling for sterilization at about 80-90 ° C. or aseptic filling Wide-mouth cup-shaped containers made of biaxially stretched PET resin or polypropylene resin are in widespread use. This cup-shaped container is used by sealing the cover by heat-sealing a lid material such as aluminum foil or resin synthetic paper using the upper surface of a flange that is provided in the shape of an outer casing at the upper end.

  For example, Patent Document 1 has a description of a biaxial stretch blow molding method for a wide-mouthed cup-shaped container made of PET resin, but the biaxial stretch blow molding is as shown in the schematic explanatory diagram of FIG. The flange 114 portion of the small cup-shaped preform 111 having the flange 114 provided around the upper end is fixed, biaxial stretch blow molding is performed, and the cup-shaped container 101 is molded.

  Here, in the biaxially stretched blow molded product, the biaxially stretched portion has improved heat resistance due to orientation crystallization by stretching, but the mouth tube portion of the PET bottle or the cup-shaped container 101 described above. Although the flange 104 is in an unstretched state and has a heat resistance of about 70 ° C., it is thermally deformed by a filling process at a high temperature as described above or a hot air sterilization process of hydrogen peroxide.

In order to improve the heat resistance of the non-stretched portions such as the above-mentioned tube portion and flange, only these portions are heated in a preform state or in a container state to perform a thermal crystallization treatment (so-called “so-called” portion). Whitening treatment).
For example, Patent Document 2 describes a method in which a hot plate is brought into contact with a flange of a cup-shaped container to partially perform thermal crystallization.
JP 2004-268570 A JP 2004-58602 A

However, when the flange is subjected to thermal crystallization treatment, there is a problem that crystallization of the upper surface of the flange makes it difficult for the upper surface of the flange to melt or soften at a normal heat seal temperature, so that sufficient sealing strength cannot be obtained.
In addition, the method using a hot plate has the advantage that the thermal crystallization process can be carried out in a short time with relatively simple equipment. However, the component volatilized by heat is trapped between the flange surface and the hot plate. Conventionally, there is a problem that small crater-like irregularities are generated on the upper surface of the flange that is in contact with the hot plate, and this irregularity causes incomplete sealing with the lid.

Therefore, the present invention aims to solve the problem relating to the heat sealability of the flange subjected to the heat crystallization treatment, and the problem of heating by the hot plate, and can make the sealing strength of the lid material suitable. It aims at providing the cup-shaped container which has the outstanding heat resistance.

Of the present invention for solving the above technical problem, the means of the first invention is:
In a synthetic resin cup-shaped container,
Having a flange subjected to thermal crystallization treatment by a hot plate;
The top surface of this flange is in a state where it has been roughened so that the sealing strength of the lid material by heat sealing becomes a necessary and sufficient size,
It is in.

With the above configuration of the first invention , even when the top surface of the flange is difficult to melt or soften due to thermal crystallization during heat sealing, the lid material is usually softened to the adhesive layer at a relatively low temperature and thermally melted. A hot melt type adhesive that can be worn is used, and the top surface of the flange has fine irregularities formed by roughening, so the hot melt type adhesive is deformed along the irregularities. Thus, the lid material is heat-sealed, and the necessary and sufficient sealing strength can be obtained.

Here, the reason why the “necessary and sufficient seal strength” is set in the first invention is that if the seal strength is too high, peeling during use becomes difficult. By appropriately determining the roughening pattern in the roughening treatment or the degree of unevenness, it is possible to balance seal strength and peelability.

The means of the second invention is that, in the first invention , the surface of the flange contacting the upper surface of the flange is used, and the upper surface of the flange is roughened simultaneously with the thermal crystallization process, It is in.

As a roughening treatment method, it is possible to roughen the surface mechanically by cutting or the like after thermal crystallization, but with the above configuration of the second invention , the surface in contact with the upper surface of the flange is roughened. By using a hot plate, the upper surface of the flange can be roughened at the same time as the thermal crystallization process, the process can be simplified, and the manufacturing cost can be reduced. Moreover, since it is in the heated state, roughening with various patterns can be facilitated.

According to a third invention , in the second invention , a porous metal material member is used in at least a portion of the hot plate contacting the upper surface of the flange, and trapped between the upper surface of the flange and the hot plate surface by the hole of the porous metal material. The upper surface of the flange is roughened by utilizing the surface irregularities of the porous metal material part at the same time as the volatile component is absorbed or discharged to the outside. That's it.

According to the above configuration of the third invention , the top surface of the flange can be roughened using fine irregularities on the surface of the porous metal material member, and the top surface of the flange and the hot plate surface can be formed by the holes of the porous metal material member. Volatile components trapped in between can be absorbed or released to the outside through this hole.

  And, by the action of absorbing or releasing the volatile component through this hole, “the component volatilized by heating is trapped between the flange surface and the hot plate, and small crater-like irregularities are formed on the flange surface where the hot plate contacts. The conventional problem of the thermal crystallization treatment method using a hot plate can be solved, and the flange upper surface is flat with no crater-like irregularities. The seal strength can be controlled to an appropriate size more reliably including the balance with the peelability.

  Here, a ceramic material can be used as the porous material member. However, since it is used as a hot plate, it is formed from a sintered metal, for example, from the viewpoint of thermal conductivity and strength, and a porous hole having a communicating hole is formed. The use of a porous metal material is preferred.

According to a fourth aspect of the invention , in the first, second, or third aspect of the invention , the PET resin is used.

  The PET resin can provide a cup-shaped container having excellent transparency and high rigidity by injection molding, biaxial stretch blow molding of a preform, and heating a sheet molded product into a biaxial stretch shape. By molding, a cup-shaped container having more excellent heat resistance, rigidity, strength, and gas barrier properties can be provided.

In the fourth invention , PET is mainly used as the PET-based resin. However, as long as the essence of the PET resin is not impaired, a copolymer polyester mainly containing ethylene terephthalate units and containing other polyester units is also used. In addition, for example, in order to improve gas barrier properties and heat resistance, resins such as nylon resins and polyethylene naphthalate resins can be blended and used. Examples of the component for forming the copolyester include dicarboxylic acid components such as isophthalic acid, naphthalene 2,6 dicarboxylic acid, and adipic acid, propylene glycol, 1,4 butanediol, tetramethylene glycol, neopentyl glycol, cyclohexanedimethanol, Mention may be made of glycol components such as diethylene glycol.

Furthermore, in the fourth invention , as a PET resin cup-shaped container or preform, as long as the essence of the PET resin is not impaired, for example, in order to improve heat resistance and gas barrier properties, It may be laminated with other resins such as polyethylene naphthalate resin or PET resin / nylon resin / PET resin.

The thermal crystallization treatment of the flange may be performed in a cup-shaped container that is the final molded product, or may be performed in a preform, and can be selected in consideration of the entire production process. The preform is a smaller molded product, and since the molded product is thick overall, it is easy to hold the posture with a jig, and generally has an advantage that it can be implemented with high production.

The present invention is a method having the above-described configuration, and has the following effects.
In the first invention , the upper surface of the flange is roughened by appropriately determining the roughening pattern or the size of the irregularities, thereby including the balance between the sealing strength of the lid member and the peelability. It can be made large enough.

In the second invention , by using the heat-treated plate, the surface roughening can be performed simultaneously with the thermal crystallization treatment, the process can be simplified, and the manufacturing cost can be reduced. . Moreover, since it is in the heated state, roughening with various patterns can be facilitated.

In the third invention , the top surface of the flange can be roughened using the irregularities on the surface of the porous metal material, and trapped between the top surface of the flange and the hot plate surface by the holes of the porous metal material. It is possible to absorb the volatilized component or to escape to the outside through this hole, thereby eliminating the occurrence of small crater-like irregularities.

In the fourth invention , the PET-based resin is a synthetic resin suitable for biaxial stretch molding, and has excellent heat resistance, strength, by biaxial stretch blow molding and thermal crystallization treatment of the flange. A cup-shaped container having gas barrier properties can be provided.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is an explanatory view schematically showing an example of a heating device used for thermal crystallization treatment of a flange of a synthetic resin cup-shaped container of the present invention.
In this embodiment, thermal crystallization treatment of the flange is performed at the preform stage, and the preform 11 used is made of injection-molded PET resin, is colorless and transparent, and is entirely amorphous. The preform 11 has a small cup shape, has a bottom portion 13, an upper end portion of the body portion 12 is a cylindrical neck portion 15, and a flange 14 is provided around the upper end in the shape of an outer casing. The flange 14 has a width of 4 mm, an average thickness of 2 mm, and an outer diameter of 80 mm.

  The thermal crystallization process is performed with the flange 14 in a pair of upper and lower annular shapes, basically sandwiched between iron hot plates 21a and 21b. In this embodiment, the upper surface 14a of the flange 14 of the upper hot plate 21a is formed. The contacting portion is a porous metal material member 22 made of a porous metal material (Poseracs II manufactured by Shinto Kogyo Co., Ltd.), and an air passage 23 extending from the porous metal material member 22 to the outside is disposed. Yes.

  Here, the porous metal material used in this example has pores communicating, and has air permeability as a whole, and average pore diameters of 7 μm and 21 μm. The degree of the rough surface (unevenness) on the surface can be changed, and the degree of the rough surface (unevenness) for obtaining a necessary and sufficient seal strength can be selected.

Next, the preform 11 and the hot plate 21 shown in FIG. 1 were used, the temperature of the hot plate 21 was set to 165 ° C., and the thermal crystallization treatment of the flange 14 was performed with a heating time of 10 seconds.
Then, in the thermal crystallization process under the above conditions, the entire flange 14 portion was whitened by crystallization, and the flange upper surface 14a was roughened over the entire surface to form minute irregularities (the roughened region in FIG. 2). R).

Further, no crater-like irregularities were formed on the upper surface 14a of the flange 14, and an overall flat flange surface could be realized.
In the case where the porous metal material member 22 is not used in the portion in contact with the upper surface 14a of the flange 14, crater-like irregularities are frequently generated when the thermal crystallization treatment is performed under the same conditions. It was confirmed that the absorption or ventilation function related to the volatilized component was exhibited and the drawbacks of the conventional hot plate could be eliminated.

  FIG. 3 shows a cup-shaped container 1 obtained by biaxially stretch-blow-molding (see FIG. 4) a preform 11 obtained by thermally crystallizing the flange 14 under the conditions of the above embodiment. It has a bottom part 3 and a cylindrical body part 2, and a flange 4 is provided around the upper end of the neck part 5 in the shape of an outer casing. Moreover, the cover material 6 is adhere | attached by heat sealing using this flange 4, and the state which sealed the container is shown.

  As shown in the enlarged view of FIG. 3, the lid member 6 is a laminate of a base material 6a and an adhesive layer 6b. As the substrate 6a, a polypropylene resin film, a PET resin film, a synthetic paper composed of a synthetic resin and an inorganic filler, an aluminum laminate film, or the like can be used. As the adhesive layer 6b, for example, a low density polyethylene resin, ethylene- A hot melt type such as vinyl acetate copolymer can be used.

As described above, the crater-like irregularities were not formed on the upper surface 4a of the flange 4, and the entire surface was flat, and the lid 6 was reliably heat-sealed. Further, since the top surface 4a of the flange 4 is formed with fine irregularities due to the roughening treatment, even if the crystallized top surface 4a of the flange 4 is not sufficiently melted or softened at the time of heat sealing, the hot melt type The adhesive layer 4b softens at a relatively low temperature, deforms along the fine irregularities, and adheres to the upper surface 4a of the flange 4.
For this reason, necessary and sufficient seal strength could be secured.

In addition, although the said Example is an example which performs the flange 14 thermal crystallization process in the state of the preform 11, performing the thermal crystallization process of the flange 4 in the state of the cup-shaped container 1 which is a final molded product is also possible. it can.
In addition, after the thermal crystallization process by the hot plate 21, a cooling process for cooling in a state where the flange is sandwiched by the cooling plate may be provided as necessary.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to an above-described Example. For example, a biaxial stretch blow-molded cup-shaped container is not limited to a PET resin, and a polypropylene-based cup is also a cup-shaped container having excellent heat resistance and strength by biaxial stretch blow molding.

In addition to the cup-shaped container formed by biaxial stretch blow molding, the effect of the present invention can be sufficiently exerted for a thermo-formed cup-shaped container or an injection-molded cup-shaped container. It is extremely effective in promoting crystallization, increasing rigidity, and improving heat resistance.

As described above, the cup-shaped container of the present invention is an improvement in heat-sealability degradation due to thermal crystallization, and eliminates the conventional drawbacks of thermal crystallization using a hot plate, and has improved heat resistance. It is expected to be widely used and deployed in required applications.

It is explanatory drawing which shows roughly an example of the heating apparatus used for the thermal crystallization process of the flange part of the synthetic resin cup-shaped containers of this invention. It is a top view of the preform in FIG. It is a half vertical front view which shows the cup-shaped container obtained by biaxially stretching blow-molding a preform. It is a schematic explanatory drawing of the biaxial stretch blow molding of a cup-shaped container.

DESCRIPTION OF SYMBOLS 1; Cup-shaped container 2; Body part 3; Bottom part 4; Flange 4a;
4b; Lower surface 5; Neck 6; Lid 6a; Base material 6b; Adhesive layer 11; Preform 12; Body 13; Bottom 14; Flange 14a;
14b; lower surface 15; neck 21; hot plate 21a; upper hot plate 21b; lower hot plate 22; porous metal material member 23; vent 101; cup-shaped container 104; flange 105; Flange 115; neck R; roughened portion

Claims (1)

A cup-shaped container made of polyethylene terephthalate resin and having a flange (4) disposed at the upper end,
The flange (4) is subjected to a thermal crystallization treatment by a hot plate (21) using a porous metal material member at least in a portion in contact with the upper surface (4a),
The volatile component trapped between the upper surface (4a) and the hot plate (21) surface is absorbed by the holes of the porous metal material member, or is thermally crystallized in a state where it escapes to the outside,
In a state where the upper surface (4a) has been roughened using the irregularities on the surface of the porous metal material member so that the sealing strength of the lid material (6) by heat sealing is sufficiently large. A cup-shaped container made of synthetic resin.

Images