JP2014210342A - Method for producing container, and container with bottom rib - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a container with a bottom rib, which is the deep-drawn container having a drawing ratio equal to or higher than 0.4, and to provide a method for producing the container, in which the container with the bottom rib can be formed in an excellent state.SOLUTION: The method for producing the container comprises the steps of: using a stationary die having a recessed part corresponding to an external shape of the container and a movable die which is disposed at the bottom of the recessed part and can be moved vertically in the depth direction of the recessed part; picking up a thermoplastic resin foam sheet by the movable die at the bottom and folding the thermoplastic resin foam sheet existing on the outside of the movable die to produce the container 20 having the bottom rib 22a in a bottom surface part when the heated thermoplastic resin foam sheet is thermoformed along the recessed part; and heating the tip of a projected part to the temperature higher than those of a base end part of the projected part and a female die in order to form the bottom surface part 22b, forcing the thermoplastic resin foam sheet to intrude into the recessed part of the female die, and performing evacuation from the female die side to produce the container 20 having the drawing ratio equal to or higher than 0.4.

Description

  The present invention relates to a container manufacturing method and a container with a thread end, and more specifically, a fixed mold having a recess corresponding to the outer shape of the container to be manufactured, and a depth direction of the recess disposed in the bottom of the recess. A mold having a movable mold movable to the bottom, and when the heated thermoplastic resin foam sheet is thermoformed along the recess, the thermoplastic resin foam sheet is lifted by the movable mold at the bottom, The present invention relates to a container manufacturing method in which a thermoplastic resin foam sheet outside the movable type is folded to produce a yarn tail-attached container having a thread tail at the bottom, and a yarn tail-attached container produced by such a production method.

  Conventionally, foods such as instant noodles in which dry noodles and powdered soup are contained in cup-shaped containers have been widely used, and this instant noodle container has a relatively high strength while being lightweight, Resin containers formed of thermoplastic resin sheets are widely used because they are relatively inexpensive.

As the thermoplastic resin sheet used for forming such a resin container, a solid sheet (thermoplastic resin film) and a thermoplastic resin foam sheet are known, and as the thermoplastic resin foam sheet, a foam layer is used. A single layer, a laminate of a plurality of foam layers, a laminate of one or more foam layers and one or more solid layers are widely used.
When forming a resin container using this kind of thermoplastic resin sheet, the thermoplastic resin sheet heated and softened by using a mold having a molding surface recessed corresponding to the outer shape of the container A method of deforming along the molding surface has been widely adopted, vacuum forming to deform the thermoplastic resin sheet along the molding surface by evacuating from the vacuum hole opened at the bottom of the molding surface, There are widely adopted molding methods such as pressure molding in which a thermoplastic resin sheet is pressed from the side opposite to the mold and deformed along the molding surface, and vacuum / pressure molding in which both are performed.

In addition, when the ratio (drawing ratio) of the depth (≈container height) to the opening diameter of the concave portion forming the molding surface is increased, a good container can be obtained simply by evacuation or compressed air. In order to make it difficult to obtain, the above mold is used as a female mold, and a male mold provided with a convex portion serving as a core that enters the concave portion of the female mold is further used, and the thermoplastic resin sheet is formed at the convex portion. A method of performing the vacuum forming while intruding into a female recess is employed.
However, in general, the thermoplastic resin foam sheet is less likely to exhibit uniform elongation compared to the thermoplastic resin film.For example, when trying to form a deep-drawn container having a drawing ratio of 0.4 or more by the thermoplastic resin foam sheet, It is difficult to obtain a non-defective product because the container is extremely uneven in thickness and is easily broken in some cases.

By the way, in recent years, as the mold, there is a mold having a fixed mold that is recessed corresponding to the outer shape of the container, and a movable mold that is arranged at the bottom of the fixed mold and is movable up and down in the depth direction of the fixed mold. Used, an annular fold is provided on the bottom surface of the container by the moving operation, and a rib called a thread tail such as a ceramic plateau is formed on a resin container (see Patent Document 1). ).
A container with a thread tail in which such a thread tail is formed is usually easy to place on a table or the like in a stable state, and since the contact area with the table is small, it is difficult for heat and cold to escape and has excellent heat retention. Yes.
In addition, since the container with a thread tail has an advantage that it is easy to exert excellent compressive strength by the thread tail, it is required to provide such a structure in the resin container.
However, in the deep-drawn container as described above, in order to form the thread bottom on the bottom surface portion, the thermoplastic resin foam sheet is stretched uniformly until reaching the deepest portion of the concave portion of the mold, and further stretched. The thermoplastic resin foam sheet must be folded inward at the front end in the direction, and the resulting product tends to be broken, wrinkled, and extremely uneven in thickness, making it difficult to obtain a good product.

  In contrast, Patent Document 2 below uses a thermoplastic resin foam sheet having a solid layer on the surface, and facilitates deep drawing by forming an inner surface of the cup with the solid layer. It is described that a cup-shaped resin container is formed.

However, the invention described in Patent Document 2 has not been studied even for forming a thread tail, and a container with a thread tail that has been deeply drawn with a drawing ratio of 0.4 or more in a good state. It is not intended to provide a container manufacturing method that can be formed.
That is, the conventional container manufacturing method has a problem that it is difficult to form a yarn tailed container that is deeply drawn with a drawing ratio of 0.4 or more in a good state.

JP 2006-334972 A JP 2005-247354 A

  The present invention has been made in view of the above problems, and is a container with a thread tail that has been deeply drawn with a drawing ratio of 0.4 or more, and a container that can form the container with a thread tail in a good state. It is an object to provide a manufacturing method.

  As a result of investigations to solve the above problems, the present inventor has a fixed mold having a recess corresponding to the outer shape of the container to be manufactured, and is arranged at the bottom of the recess and can move up and down in the depth direction of the recess. The present invention is completed by finding that a deeply drawn yarn-tailed container can be formed in a good state by using a mold having a movable mold as a female mold and using a male mold having a predetermined function. Has been reached.

  That is, the present invention relating to the container manufacturing method includes a fixed mold having a recess corresponding to the outer shape of the container to be manufactured, and a movable mold that is arranged at the bottom of the recess and is movable up and down in the depth direction of the recess. When a heated thermoplastic resin foam sheet is thermoformed along the recess using a mold, the thermoplastic resin foam sheet is lifted by the movable mold at the bottom, and the thermoplastic resin outside the movable mold A container manufacturing method for folding a foamed sheet to produce a container with a thread tail on the bottom surface, wherein the mold is a female mold, and a male mold having a convex portion corresponding to the inner surface of the container is used together with the female mold The thermoforming is performed, and at the time of the thermoforming, the tip of the convex part for forming the bottom surface part is heated to a temperature higher than that of the base end part of the convex part and the female mold. Thermoplastic resin foam Evacuated conducted aperture ratio from the female side with advancing the bets in the recess of the female type is characterized by making a 0.4 or more Itojiri container with.

  Further, the present invention related to a container with a thread end includes a fixed mold having a recess corresponding to the outer shape of the container to be manufactured, and a movable mold that is arranged at the bottom of the recess and is movable up and down in the depth direction of the recess. When the heated thermoplastic resin foam sheet is thermoformed along the recess using the mold having the mold, the thermoplastic resin foam sheet is lifted by the movable mold at the bottom, and the thermoplastic resin outside the movable mold A container with a thread bottom formed by folding a resin foam sheet to form a thread tail on the bottom surface, wherein the mold is a female mold, and a male mold having a convex portion corresponding to the inner surface of the container is used together with the female mold The thermoforming is performed, and at the time of the thermoforming, the tip portion of the convex portion for forming the bottom surface portion is heated to a higher temperature than the base end portion of the convex portion and the female mold, and the convex portion The thermoplastic resin foam sheet is the female It is characterized in that while being entered into the recess of the evacuation from the female side is formed in a drawing ratio of 0.4 or more by being implemented.

According to the manufacturing method of the present invention, since the tip of the female convex portion is heated, the temperature of the thermoplastic resin foam sheet is suppressed from being lowered while the male die is deformed. Since the temperature drop of the bottom surface portion of the container where the bottom shape is formed is suppressed, it is possible to suppress the loss of easy deformability at the bottom surface portion.
Accordingly, a yarn tailed container having a deep drawing with a drawing ratio of 0.4 or more can be formed in a good state.

The schematic sectional drawing which shows the structure of the thermoplastic resin foam sheet (laminated foam sheet) used in this embodiment. The schematic sectional drawing which shows the resin-made containers produced with the manufacturing method which concerns on this embodiment. The schematic sectional drawing which shows the metal mold | die structure used for the manufacturing method of a resin foam sheet.

Hereinafter, preferred embodiments of a container with a yarn end and a manufacturing method thereof according to the present invention will be described with reference to the drawings.
First, a thermoplastic resin foam sheet used in the container manufacturing method of the present embodiment and a container using the thermoplastic resin foam sheet will be described.
FIG. 1 is a cross-sectional view of a thermoplastic resin foam sheet used in the present embodiment. As shown in FIG. 1, the thermoplastic resin foam sheet 10 according to the present embodiment contains bubbles. It has a two-layer structure of a solid layer 11 formed in a non-foamed state and a foamed layer 12 formed in a foamed state.

As the thermoplastic resin foam sheet 10 having this laminated structure, for example, a thermoplastic resin foam (hereinafter simply referred to as “resin”) is formed on a thermoplastic resin foam sheet composed only of a foam layer that can be obtained by general extrusion foaming. A film in which the solid layer 11 is formed by laminating the thermoplastic resin film may be employed.
Moreover, as the thermoplastic resin foam sheet 10, a sheet formed by coextrusion of the solid layer 11 and the foam layer 12 can be employed.
In the following detailed description, a thermoplastic resin foam sheet having a laminated structure is referred to as a “laminated foam sheet 10”, and a thermoplastic resin comprising only a foam layer for constituting the laminated foam sheet 10 The foam sheet is simply referred to as “foam sheet” to be distinguished.

  In the present embodiment, a deeply drawn yarn bottomed container having a drawing ratio of 0.4 or more (usually 1.5 or less) is produced using the laminated foamed sheet 10, so that the thickness is significantly uneven. The laminated foam sheet 10 is preferably one that does not easily cause heat shrinkage during molding in that a good yarn-tipped container without tearing can be more reliably formed. In this heat shrink property, the foam sheet extrusion direction is preferable. It is preferable that there is no significant difference between the (MD direction) and the width direction (TD direction) orthogonal to the extrusion direction.

That is, the laminated foamed sheet to be used has a heat deformation (length after heating in the MD direction / length after heating in the TD direction) of 0.90 to l.d. 10 and the heating deformation ratio obtained by dividing the length after heating for molding by the length before molding heating is 0.95-l. 10 is preferable.
In particular, the heat deformation (length after heating of MD / length after heating of TD) is 0.97 to l. 05, and the heating deformation ratio is 0.97 to 1 in both MD and TD. It is preferably 08.

The foamed sheet for forming the foamed layer 12 is not particularly limited in its constituent materials, but in the present embodiment, a styrene resin is used, and as the styrene resin, styrene, methyl Examples include styrene, ethyl styrene, isopropyl styrene, dimethyl styrene, paramethyl styrene, chlorostyrene, promostyrene, vinyl toluene, and vinyl xylene homopolymers or copolymers. For example, specific resin names include styrene -Maleic anhydride copolymer, styrene-acrylic acid copolymer, styrene-acrylonitrile resin, acrylonitrile-butadiene-styrene resin and the like.
When heat resistance is required, a heat-resistant polystyrene resin can be used. For example, a styrene copolymer containing 3 to 15% by mass of acrylic acid, methacrylic acid, acrylonitrile, and maleic anhydride is preferable.
Further, as the heat-resistant polystyrene resin, a mixture of polystyrene (GPPS) and polyphenylene ether (PPE) can be employed.

The polystyrene resin may further be mixed with rubber such as butadiene rubber, ethylene propylene rubber, ethylene butadiene rubber, isoprene, chloroprene, a copolymer of butadiene and styrene, and when these are mixed, The mixing amount is preferably about 0.05% by mass to 15% by mass.
Such a mixing amount is preferable because if it is less than 0.05% by mass, cracks may occur during handling depending on the combination with the laminated thermoplastic resin film, and if it exceeds 15% by mass. This is because the strength may be insufficient.
Further, the above rubber component is mixed with polystyrene resin, and further, 0.1 to 40% by mass of polyolefin resin such as polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer is mixed to provide heat resistance. Improvements can also be made.
However, when strength is required, the rubber content is preferably adjusted to 5% by mass or less.

In order to obtain a foamed sheet using this polystyrene-based resin, extrusion foaming may be performed by adding a foaming agent or the like as described above.
At this time, 0.5 to 15% by mass of a filler can be added to improve the dischargeability from the die, surface properties (aesthetics), heat resistance, and the like.
Examples of such fillers include talc, calcium carbonate, shirasu, gypsum, carbon black, white carbon, magnesium carbonate, clay, general inorganic fillers such as natural silicic acid, and metal powders. The material may be used as a master batch before being put into the extruder.
Moreover, you may add a bubble regulator, a pigment, etc. as another compounding agent, for example.

As the foaming agent, various volatile foaming agents and decomposable foaming agents can be used.
The volatile blowing agent, a hydrocarbon, propane, i- butane, n- butane, i- pentane, n- pentane or a mixture thereof, _{and, N 2, CO 2, N} 2 / CO 2, water, or , -OH, -COOH, -CN, -NH 3, -OSO 3 H, -NH, CO, NH 2, -CONH 2, -COOR, -CHSO 3 H, -SO 3 H, -COON 4, -COONH Examples thereof include a mixture of water having ₄ groups and water.

Examples of the decomposable foaming agent include foaming agents such as azodicarboxylic acid amide, dinitropentamethylenetetramine, and 4,4′-oxybis (benzenesulfonylhydrazide).
Furthermore, a combination of an organic acid such as sodium bicarbonate or citric acid or a salt thereof and a bicarbonate can be used.
Further, for example, organic acids such as sodium bicarbonate citric acid or a combination of a salt thereof and a bicarbonate can be used, but these can be used even when coated with a low molecular weight olefin, liquid paraffin, beef tallow oil or the like. .
In addition, it is also possible to use a mixture of these, and two or more of these may be mixed.
All of these can also be obtained as a masterbatch with powder, flakes, or thermoplastic resin.

The expansion ratio of the foam sheet is usually about 1.2 to 15 times, and preferably 1.3 to 10 times.
Although the thickness of the said foam sheet is not specifically limited, Usually, it is about 0.3-5.0 mm, Preferably, it is about 0.5-3.0 mm.

The thermoplastic resin film for laminating the foamed sheet to form the solid layer 11 of the laminated foamed sheet 10 is not particularly limited in its forming material. For example, the polystyrene resin shown for the foamed sheet Can be used.
In addition, a mixed resin of polystyrene resin and impact-resistant polystyrene (high-impact polystyrene resin: HIPS), or a material in which a styrene-butadiene block copolymer is dispersed in a salami structure in impact-resistant polystyrene can be preferably used. .
In the case of using a styrene-butadiene block copolymer dispersed in a salami structure, it is preferable that most of the styrene-butadiene block copolymer is contained in a particle size of 0.3 to 10 μm.

Other examples of resins that can be used for thermoplastic resin films include linear low density polyethylene, high density polyethylene, low density polyethylene, polypropylene, ethylene-propylene random polymer, ethylene / propylene block polymer, and ethylene-propylene butene-copolymer. , Ethylene-vinyl acetate copolymer, ethylene-unsaturated carboxylic acid ester copolymer (for example, ethylene-methyl methacrylate copolymer), ethylene-unsaturated carboxylic acid metal salt copolymer (for example, ethylene- Magnesium acrylate (or zinc) copolymer), propylene-vinyl chloride copolymer, propylene-butene copolymer, propylene-maleic anhydride copolymer, propylene-olefin copolymer (propylene-ethylene copolymer, propylene-butyl copolymer) Down 1 copolymer) polyethylene or polypropylene unsaturated carboxylic acids (e.g., maleic acid) modified product anhydride, ethylene - propylene rubber, atactic polypropylene, and the like.
In addition, Preferably, films, such as polyethylene, an ethylene propylene copolymer, a propylene-butene-1 copolymer, these 2 or more types of mixtures, a polyethylene terephthalate, a polybutylene terephthalate, are mentioned.
When a polypropylene resin film is employed, any of unstretched, uniaxially stretched, and biaxially stretched can be used. Particularly, when an unstretched film is used, it is preferable because of good moldability.

This thermoplastic resin film can be used by mixing 0.01 to 3% by mass of silicon oil from the viewpoint of production efficiency in the container production method.
By including 0.01% by mass or more of silicon oil, it is possible to expect an effect such as improvement of releasability and prevention of blocking when the container is molded. Excellent printing properties can be expected due to good sliding with the blanket of the machine.
Moreover, it becomes easy to ensure the extrusion stability at the time of manufacturing the said resin film, and can make a film external appearance favorable by content of silicon oil being 3 mass% or less.
When the silicone oil is contained in the thermoplastic resin film, it is up to about 0.2% by mass that the resin can be kneaded with the blend, and beyond this, the resin slips and does not stably bite into the screw. To mix more than 0.2% by mass to 3% by mass, kneading into a resin with a mixing roll such as a calender roll, or adding it during the polymerization or pelletizing process after polymerization, etc. It is preferable to carry out by a so-called injection method in which press-fitting is performed in the middle of the extruder.

It should be noted that silicon oil is kneaded into 0.01% to 0.2% by weight resin, and if further effect is required, the resin is kneaded into 0.01% to 0.2% by weight resin. If there is no uneven coating even when silicone oil is applied on the film, it can be determined that uneven printing does not occur.
In addition, an antistatic agent such as stearic acid monoglyceride can be kneaded with silicon oil at the same time.
Further, silicon oil may be mixed also on the foam sheet side, and improvement effects such as bubble moldability can be expected by mixing the silicon oil.
In addition, printing may be performed on a thermoplastic resin film kneaded with silicon, and then a printed surface or an unprinted surface may be bonded to a polystyrene resin foam sheet. Moreover, when white fillers, such as titanium white and a calcium carbonate, are mixed with a thermoplastic resin film 0.1 to 3.0 mass%, printability will become good.

It is preferable to use a resin film having a thickness of 5 to 600 μm.
In some cases, a laminated foam sheet in which a thermoplastic resin film is laminated on both surfaces of the foam sheet may be employed.
When the thickness of the resin film to be employed is 5 μm or more, the elongation at the time of molding becomes good, and further excellent mechanical strength can be imparted to the obtained molded product.
Further, by making the thickness of the resin film 600 μm or less, it is possible to improve the punchability after molding, and at the time of punching, it is possible to suppress the bubbles in the lip portion from being crushed and being in a communication state, The problem that a resin film and the said foam sheet peel can be prevented.
In such a point, it is particularly preferable to employ a thermoplastic resin film having any thickness within the range of 30 to 500 μm.

As a method of laminating the foamed sheet and the resin film as described above to obtain a laminated foamed sheet, a method of adhering via an adhesive layer can be employed.
In this case, a layer formed by extrusion laminating an ethylene-vinyl acetate copolymer, a partially saponified ethylene-vinyl acetate copolymer, chlorinated polyethylene, chlorinated polypropylene, etc. on a resin film, polybutadiene, An adhesive layer is a layer formed by extrusion laminating a resin film prepared by mixing isoprene, styrene-butadiene copolymer, styrene-isoprene copolymer or the like with a polyolefin resin such as polypropylene or polyethylene. Can be used.
The adhesive layer is made of vinyl resin such as polyvinyl acetate, polyvinyl chloride, and polyvinylidene chloride, cellulose resin such as nitrocellulose, ethyl cellulose, and cellulose acetate, epoxy resin, acrylonitrile-butadiene copolymer, and the like. An adhesive dissolved in an organic solvent may be applied to the thermoplastic resin film and then dried to form the adhesive.

Other methods include the co-extrusion method. When a thermoplastic resin film is laminated on a foam sheet in a die, a confluence die (for example, a crosshead die) may be used. Lamination may be performed by flowing in before the slit.
Further, a method of extruding and laminating a thermoplastic resin film after extruding and foaming a foam sheet can also be employed.

In addition, when using the container with a thread tail produced by the container manufacturing method of the present embodiment as a food container, a product obtained by bonding a barrier film to a foam sheet in order to improve the shelf life of the food to be stored, or A laminated foamed sheet obtained by laminating a thermoplastic film and a barrier film previously laminated can be suitably used.
Specific examples of the barrier film include an ethylene / vinyl acetate copolymer film, a polyvinyl alcohol film, a polyvinylidene chloride film, a polyamide film, a polyester film, a polyacrylonitrile film, and a vinylidene chloride / acrylonitrile copolymer film. , Acrylonitrile-based methyl methacrylate / butadiene copolymer film, high-density polyethylene film, ionomer resin film (for example, registered trademark Surlyn), biaxially stretched products thereof, or metal vapor-deposited films. It can be used singly or as a laminated product in which a plurality of layers are laminated.

As described above, the laminated foamed sheet 10 used in this embodiment has a length after heating of MD / the length after heating of TD of 0.90 to 1. It is preferable that the heating deformation ratio obtained by dividing the length after heating for molding by the length before molding heating is 0.95 to 1.10 for both MD and TD.
Further, preferably, the length after heating of MD / the length after heating of TD is 0.97 to l. The heating deformation ratio obtained by dividing the length after heating for molding by the length before molding heating is 0.97 to 1.08 for both MD and TD.

The heating for molding is determined by the temperature and time when the laminated foam sheet is actually molded by a molding machine.
For example, when the temperature measured at the intermediate position from the wall of the heating furnace to the laminated foam sheet in the thermoforming machine is the atmospheric temperature in the thermoforming machine, the surface of the laminated foam sheet melts when placed in this ambient temperature. The shorter one of the time when the state or thickness starts to decrease is set as the overheating time, and about 80 to 95% of the overheating time can be set empirically to be the heating time for molding. .
And, for example, draw a square with a side of 500 mm at the center of a square laminated foam sheet with a side of 600 mm cut out so that the two opposite sides are parallel to the MD direction and the TD direction, respectively. Clamp and heat under the above conditions, measure the length in the MD direction at the approximate center of the square drawn with the clamp removed after heating, the length in the TD direction, and deform by heating (length after heating in the MD direction / TD Length after heating in the direction).
Further, the heating deformation ratio can be obtained by dividing the length in the MD direction and the length in the TD direction after heating by 500 mm.
In order to more reliably form a yarn-tailed container having a drawing ratio of 0.4 or more in a good state, these values satisfy both the front side and the back side of the laminated foam sheet 10 in evaluating the above characteristics. It is important that

In order to impart the above heat deformation characteristics to the laminated foamed sheet 10 obtained by laminating a resin film on a foamed sheet using a polystyrene-based resin as shown above, a cylindrical mold (circular die) is used. When the foam sheet is extruded and foamed by use, the blow-up ratio, which is the ratio of the plug diameter divided by the mold slit diameter, is 1.8 to 3.5, and the gap between the mold slits is 0.25 to 1. 2 mm, the extruder temperature is preferably 150 to 265 ° C, and the temperature of the molten resin in the vicinity of the mold outlet is preferably 145 to 185 ° C.
The amount of extrusion varies depending on the extruder used, but generally it may be set appropriately at 75 to 400 kg / h depending on the extruder used.
Furthermore, after extrusion from a cylindrical mold and foaming into an annular sheet, cooling is performed with air, and the amount of cooling air at this time is about 0.04 to 0.3 m ³ / m ^2, and the temperature of the air Is preferably about 10 ° C. to 80 ° C., and the cooling with the air is performed within 5 seconds immediately after the extrusion, from the viewpoint of more reliably obtaining a laminated foamed sheet satisfying the above characteristics.

In particular, the blow-up ratio is between 2/5 and 3/5 of the expansion ratio, and the extrusion amount is such that the island pattern in the extrusion direction of the foam sheet disappears within 1/3 of the distance from the mold slit to the plug. It is better to adjust the take-up speed and cooling conditions.
The foam shape of the central portion 2/3 of the thickness of the foamed sheet was 0.9 ≦ TD / VD ≦ 1.5, 0.9 ≦ MD / VD ≦ 1.1, and TD / VD ≧ MD / VD. .
However, in this formula, the bubble diameters are MD, TD, and VD (thickness direction).

  In the above description, the description is centered on a laminated foam sheet made of polystyrene resin as a main raw material. However, the above-exemplified laminated foam sheet can of course be employed in the container manufacturing method of the present embodiment. In general, a thermoplastic resin foam sheet used for thermoforming such as vacuum forming widely employs a foam layer only or a resin film laminated on one or both sides (laminated foam sheet). be able to.

For example, a method for producing a foamed sheet or a laminated foamed sheet mainly composed of a polypropylene resin such as propylene homopolymer, ethylene-propylene random copolymer, ethylene-propylene block copolymer, or a polyolefin resin such as polyethylene resin It can employ | adopt as a thermoplastic resin foam sheet used for.
Further, the resin film for constituting the laminated foamed sheet is not limited to the above-mentioned examples, and various resin films can be adopted depending on the application. For example, the yarn end container can suppress moisture permeability. When it is required (improved water vapor barrier properties), a cycloolefin copolymer film such as an ethylene-norbornene copolymer may be employed.
Such a laminated foam sheet or foam sheet is also preferably controlled by controlling the extrusion conditions and the like so that anisotropy in heat shrinkage characteristics does not occur between the MD direction and the TD direction.

An example of a container with a thread tail produced using such a thermoplastic resin foam sheet is shown in FIG.
As shown in this figure, the container 20 with a thread tail in the present embodiment is a dice cup-shaped container having an inverted frustoconical storage space, and the container 20 with a thread tail is circular at the top. An opening 20a is provided.
And the said container 20 with a thread | yarn end is the bottom face part provided in the lower end of the surrounding side wall part 21 and the surrounding side wall part 21 which taper down toward the downward direction from the container opening edge part 20b which has defined the said circular opening 20a. 22, and the bottom portion 22 and the peripheral side wall portion 21 form the inverted frustoconical storage space.
In addition, the container 20 with a yarn end is formed with a flange 23 extending outward from the upper end edge of the peripheral side wall 21, and the protrusion 23 has a substantially constant protrusion length in the circumferential direction. .

Further, in the container 20 with a thread tail, the laminated foam sheet 10 is folded upward on the inner side of the lower end of the peripheral side wall portion 21, and a thread tail is formed on the outer edge portion of the bottom surface portion 22.
That is, the bottom surface portion 22 of the container 20 with a yarn tail is in a state where the bottom is raised, and a central portion 22b (hereinafter also referred to as “bottom raising portion 22b”) is an outer edge portion 22a (hereinafter referred to as “thread bottom portion 22a”). It is formed to be one step higher than

In the present embodiment, the peripheral side wall portion 21 is reduced in diameter from the container opening edge portion 20b to the bottom surface portion 22 at a substantially constant rate, and has a straight outline when viewed from the front. .
The angle formed by the contour line of the peripheral side wall portion 21 with respect to the container height direction (perpendicular line) is usually 3 degrees or more and 15 degrees or less.
The drawing ratio, which is the ratio (H / D) of the container height (“H” in the figure) to the diameter (“D” in the figure) of the peripheral side wall portion 21 at the base portion of the flange 23, is 0.4. The upper limit is normally 1.5.

In the container manufacturing method of the present embodiment, the container 20 with a yarn tail having the above-described drawing ratio is manufactured because the formation of the yarn tail is relatively easy if the container has a drawing ratio less than the above-mentioned drawing ratio. The reason why the above drawing ratio is exceeded is that it is difficult to obtain a good product even in the container manufacturing method of this embodiment.
That is, in the container manufacturing method of the present embodiment, the container with a yarn bottom having a drawing ratio of 0.4 to 1.5 is manufactured in order to exhibit the effects of the present invention more remarkably.

In addition, if the basis weight (mass per unit area) of the thermoplastic resin foam sheet to be used becomes small, the “expandable” of the thermoplastic resin foam sheet will be reduced. Is even more difficult.
Therefore, the container manufacturing method of the present embodiment can exert its effect more remarkably by being used for manufacturing a container with a yarn tail having a low apparent density.
Specifically, the container manufacturing method of the present embodiment is preferably used for manufacturing a container with a yarn tail having an apparent density of 0.15 or less.

In addition, although the container 20 with a thread | yarn tail to produce is not specifically limited, If an example is given, the thing of the following sizes will be mentioned normally.
Container height (H): 50 mm to 200 mm
Maximum diameter (D) of the peripheral side wall: 50 mm to 200 mm
Yarn bottom height (Ha): 1 mm to 10 mm
Thread bottom width (Wa): 1 mm to 10 mm

Such a yarn end-equipped container 20 can be formed by thermoforming (vacuum forming) using a mold shown in FIG.
This mold is an assembled mold of a female mold 30 and a male mold 40, and the female mold 30 is disposed on a fixed mold 31 that is recessed corresponding to the outer shape of the container, and on the bottom of the fixed mold 31. The movable die 32 is movable in the depth direction of the fixed die.
The fixed die 31 of the female die 30 has an opening having a size corresponding to the diameter (D) of the upper end of the peripheral side wall portion 21 of the yarn end container 20 at the center portion of the mating surface 30a with the male die 40. The concave portion 30b is recessed, and the concave portion 30b has a side wall portion 31a that is reduced in a mortar shape toward the bottom portion corresponding to the outer surface shape of the peripheral side wall portion 21 of the yarn end container 20. And a bottom 31c extending radially inward from the lower end of the side wall 31a.
However, a circular through hole 31b for allowing the upper end 32a of the movable mold 32 to be taken in and out of the recess 30b is opened at the center of the bottom 31c, and the recess 30b is defined only by the fixed mold 31. However, it is defined by the fixed mold 31 and the movable mold 32 disposed in the through hole 31b.

The movable mold 32 has a disk shape whose upper end portion 32 a is slightly smaller in diameter than the through hole 31 b provided at the center of the bottom of the fixed mold 31, and a circular shape is formed between the movable mold 32 and the bottom 31 c of the fixed mold 31. An annular slit is formed.
And the slit opened cyclically | annularly so that this movable mold | type 32 may be enclosed is utilized as a vacuum hole at the time of vacuum-forming the laminated foam sheet 10 using the said female type | mold 30 so that it may mention later.

The male mold 40 is used to assist in deforming the laminated foamed sheet 10 along the molding surface such as the side wall 31a and the bottom 31c of the female mold 30 in the vacuum forming of the laminated foamed sheet 10. And a convex portion 42 protruding from the mating surface 40a with the female die 30.
The convex portion 42 corresponds to the inner surface shape of the yarn bottomed container 20, and an interval corresponding to the thickness of the laminated foamed sheet 10 is provided between the mating surfaces 30 a and 40 a so that the convex portion 42 is When entering the recess 30 b of the female mold 30, a gap corresponding to the thickness of the yarn end container 20 can be formed between the outer surface of the female mold 30 and the side wall 31 a of the female mold 30.
That is, the convex part 42 cooperates with the side wall part 31a of the female mold 30 at the base end part 42a to form the container opening edge part 20b, and at the front end part 42b that is on the front end side from the base end part 42a. A portion from the bottom surface portion 22 to the peripheral side wall portion 21 of the yarn end container 20 can be formed in cooperation with the female die 30.

  Therefore, the outer diameter of the convex portion 42 is smaller than the diameter of the concave portion 30b of the female die 30 by the thickness of the laminated foam sheet 10, and the protruding height ("HX" in FIG. 3) is Further, it is formed lower than the depth of the recess 30b (FIG. 3 “DX”) by the height of the yarn tail (FIG. 2 “Ha”).

In the male mold 40 in this embodiment, a heat insulating sheet 42c is interposed between the base end part 42a and the tip end part 42b, and the temperature difference between the convex part 42 is different between the base end part side and the tip end part side. It is comprised so that it can control to the state which provided.
More specifically, a heater 43 is embedded in the distal end portion 42b so that the distal end portion 42b can be heated to a higher temperature than the proximal end portion 42a.

In order to form the yarn tailed container 20 using such a mold, a method similar to a general container forming method by vacuum forming can be employed.
However, in order to produce the yarn end container 20 with a drawing ratio of 0.4 or more in a good state, the male mold 40 is heated to a higher temperature than the base end part 42a at the distal end part 42b of the convex part 42. In addition, it is important to perform vacuum forming using the female mold 30 cooled to be lower in temperature than the tip end portion 42b.

It is preferable to set the temperature of the tip end portion 42b and the base end portion 42a based on the softening temperature of the resin constituting the laminated foam sheet 10, and the temperature of the tip end portion 42b is in the range of the softening point + 5 ° C to + 35 ° C. The temperature of the base end portion 42a is preferably in the range of the softening point -30 ° C to -70 ° C.
For example, in the case of a laminated foam sheet in which a high-impact polystyrene resin (HIPS) film is laminated on a polystyrene resin foam sheet (PSP) using general-purpose polystyrene resin (GPPS), the temperature of the tip 42b is 105 to 135. ° C is preferred, and 110 to 130 ° C is more preferred.
Moreover, 30-70 degreeC is preferable and the temperature of the base end part 42a has more preferable 40-60 degreeC.
Note that the temperature of the female die 30 is normally set to be approximately the same as the temperature of the proximal end portion 42a.

The case of using a laminated foam sheet in which the PSP and the HIPS film are combined will be further described as an example. The container manufacturing method of the present embodiment can be carried out along the following steps.
(Preheating process)
The laminated foamed sheet is heated under an appropriate temperature condition to make the laminated foamed sheet suitable for thermoforming.
At this time, the mold is preliminarily subjected to temperature control as described above, and the upper surface of the movable mold 32 is placed on standby at a position substantially flush with the bottom 31c of the fixed mold 31.

(Thermoforming process)
Then, the heated laminated foamed sheet is sandwiched between the male mold 40 and the female mold 30 so that the resin film side is the female mold side, and the convex portion 42 of the male mold 40 is brought into contact with the laminated foamed sheet, as it is. The male mold 40 is moved toward the female mold 30 to advance the laminated foam sheet to the vicinity of the bottom of the concave portion 30b of the female mold 30, and at the same time, vacuuming is performed from the slit 33 (annular vacuum hole). Thus, the laminated foam sheet is pulled away from the surface of the convex portion 42 and is brought into close contact with the female mold side.
At the same time, the movable die 32 which has been in standby state with the upper surface substantially flush with the bottom portion 31c of the fixed die 31 so far is inserted into the recess by an amount corresponding to the height (Ha) of the thread tail. Then, the bottom portion 22b is formed by raising the center portion of the bottom surface portion of the laminated foam sheet, and the upper end of the laminated foam sheet is formed on the outer peripheral side to form the yarn bottom portion 22a.

(Trimming process)
The container 20 with a yarn end is subjected to nichrome cutting along the outer edge of the flange 23 or punching with a Thomson blade mold on the laminated foam sheet to which the shape of the container with the yarn end is given in the thermoforming step. Can be taken out as a final product.

(Other processes)
Further, if necessary, the final product can be obtained by applying surface printing or paper winding or film winding to the yarn tailed container obtained in the trimming step to give decorativeness.
In the container with a yarn end obtained by the container manufacturing method of the present embodiment, the tip portion 42b of the convex portion 42 of the male mold 40 has a preferable temperature in the thermoforming step (the vicat softening point of GPPS constituting the polystyrene resin foam sheet). (Typically, the temperature is higher by 5 ° C. to 35 ° C. than 102 ° C.) Therefore, the thickness of the peripheral side wall portion 21 becomes excessively uneven, or wrinkles and tears are formed in the yarn bottom 22a. This can be suppressed.
In other words, it is possible to suppress the occurrence of extremely non-uniform thickness and wrinkles, etc., so that, for example, surface printing does not cause troubles such as fading, and yield improvement to the final product is improved. Can also contribute.

In addition, although the case where the laminated foam sheet which laminated | stacked the HIPS film on PSP is illustrated in the above, the resin film is used for the foam sheet using the heat-resistant polystyrene resin containing polyphenylene ether, or this foam sheet. Similarly, in the case of producing a container with a yarn tail having a drawing ratio of 0.4 or more using the laminated foam sheet as described above, a good product can be obtained by controlling the temperature of the male mold used in the thermoforming process. Can be obtained.
That is, the front end portion 42b of the convex portion 42 is set to a high temperature of 5 to 35 ° C. of the Vicat softening point of the heat-resistant polystyrene resin, and the base end portion 42a and the female mold 30 are set to a low temperature of 30 to 70 ° C. below the Vicat softening point. As a result, it is possible to produce a yarn tailed container having a drawing ratio of 0.4 or more while suppressing the occurrence of extreme non-uniform thickness and wrinkles.

  Further, in the case of a foamed sheet using a polypropylene-based resin or a laminated foamed sheet obtained by laminating a cycloolefin copolymer film on the foamed sheet, the tip end part 42b, the base end part 42a, and the female mold are also provided. By setting 30 to a suitable temperature condition, it is possible to manufacture a container with a thread tail having a drawing ratio of 0.4 or more.

  In the present embodiment, the die cup-shaped container with a thread tail is mentioned as an example as described above, but the container with a thread tail of the present invention is not limited to such a shape, Naturally, the container manufacturing method of the present invention can be applied to manufacturing a container other than the shape exemplified in the present embodiment, such as a basket container.

  Further, in the present embodiment, the case where vacuuming is performed from a vacuum hole that is annularly opened so as to surround the movable mold is illustrated in that it is easy to form the yarn bottom part uniformly over the entire circumference. The vacuum holes may be scattered at the bottom of the fixed mold as provided in a typical vacuum forming mold.

  Further, although no further detailed description will be given in the present specification, conventionally known matters relating to the vacuum forming technique and the thread tail forming technique can be appropriately adopted within a range that does not significantly impair the effects of the present invention.

10 Laminated foam sheet (thermoplastic resin foam sheet)
DESCRIPTION OF SYMBOLS 11 Solid layer 12 Foamed layer 20 Container 20b with a thread end Container opening edge part 21 Peripheral side wall part 22 Bottom face part 22a Thread bottom part 23 Gutter part 30 Female type | mold 30b Recessed part 31 Fixed type | mold 31c Bottom part 32 Moving type | mold 33 Slit (vacuum hole)
40 Male 42 Projection 42a Base End 42b Tip 42c Insulation Sheet 43 Heater

Claims (4)

Thermoplastic resin heated using a mold having a fixed mold having a recess corresponding to the outer shape of the container to be produced and a movable mold disposed at the bottom of the recess and movable up and down in the depth direction of the recess When the foam sheet is thermoformed along the concave portion, the thermoplastic resin foam sheet is lifted by the movable mold at the bottom, and the thermoplastic resin foam sheet outside the movable mold is folded back so that a thread tail is formed on the bottom surface. A container manufacturing method for producing a yarn-tailed container having:
The mold is a female mold, and a male mold having a projection corresponding to the inner surface of the container is used together with the female mold to perform the thermoforming, and in the thermoforming, the projection for forming the bottom surface portion. Is heated to a higher temperature than the base end portion of the convex portion and the female die, and the thermoplastic resin foam sheet enters the concave portion of the female die at the convex portion and evacuates from the female die side. A container manufacturing method, characterized in that a container with a yarn tail having a drawing ratio of 0.4 or more is produced.   The container manufacturing method according to claim 1, wherein the evacuation is performed from a vacuum hole that is annularly opened so as to surround the movable mold. The container manufacturing method of Claim 1 or 2 which produces a container with a thread tail with an apparent density of 0.15 g / cm ³ or less. Thermoplastic resin heated using a mold having a fixed mold having a recess corresponding to the outer shape of the container to be produced and a movable mold disposed at the bottom of the recess and movable up and down in the depth direction of the recess When the foam sheet is thermoformed along the concave portion, the thermoplastic resin foam sheet is lifted by the movable mold at the bottom, and the thermoplastic resin foam sheet outside the movable mold is folded back so that a thread tail is formed on the bottom surface. A yarn-tailed container formed,
The mold is a female mold, and a male mold having a convex portion corresponding to the inner surface of the container is used together with the female mold to perform the thermoforming, and the convex for forming the bottom surface portion during the thermoforming. The tip of the part is heated to a higher temperature than the base end part of the convex part and the female mold, and the thermoplastic resin foam sheet enters the concave part of the female mold at the convex part and the vacuum from the female mold side A container with a thread end, which is formed to have a drawing ratio of 0.4 or more by being pulled.

Images