JPS60206622A - Method of laminating lid material for pressure-resistant container of paper - Google Patents

Abstract

PURPOSE:To produce a laminated lid free from pinholes for a container, by compression molding a paper material into a shape of a lid, and laminating plastic films onto the opposite surfaces of the lid by vacuum forming or air pressure forming. CONSTITUTION:Anchor films, for example, of polyethylenes are laminated onto opposite surfaces of a paper material, and the laminate is compression molded by a heat press into a desired lid body 3. The lid body 3 together with barrier films 4, 5 is set on a net 2 in a vacuum chamber 1. After, keeping the films by holding jigs 6, the chamber is exhausted, the films are heated by heaters 9, 10 to be softened, and then the pressure of the chamber is restored to the atmospheric pressure so that the barrier films 4, 5 may be laminated onto the opposite surfaces of the lid body 3. Since the lid is first form, and then the lamination is carried out, it is free from wrinkles and pinholes. The method is suitable for producing lids for paper containers for beer and other beverages.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for laminating a lid material for a paper-packed pressure-resistant container that is suitable for a beverage container made of liquid, the container is mostly made of paper, and has excellent incineration and combustibility.

In general, in the case of containers for carbon dioxide-containing liquids such as beer and carbonated beverages, the most problematic problem with hurraying is a drop in internal pressure due to permeation of carbon dioxide to the outside of the container.

That is, excellent barrier performance is most required.

Therefore, the present inventors have previously proposed a paper pressure-resistant container that uses an existing barrier plastic film and has significantly superior carbon dioxide gas barrier performance without increasing the thickness of the film.

That is, it is a multilayer container having a structure of barrier plastic film/paper/harrier plastic film, which is made by closely adhering a plastic film with high carbon dioxide gas barrier properties to both sides of paper.

The container described above has the following advantages.

First, the time required for the permeability to reach a stable state is extremely long, and the permeability after the stable state is much superior to that of a single layer of barrier film having the same thickness as the total thickness of the barrier film.

Second, since it contains paper waste, the outer shape can be maintained due to the rigidity of the white paper body.

Thirdly, since aluminum foil is not used, it is not only easy to burn, but also there is no risk of deterioration in barrier properties caused by breakage due to deformation during pinball or processing or when internal pressure is applied, and the barrier properties are reliable. In addition to significantly increasing the barrier properties, by appropriately selecting a barrier film, it is possible to have barrier properties that are equal to or better than aluminum foil laminated paper.

Fourth, since the basic structure is three layers: barrier film/paper/barrier film, there is less lamination process compared to aluminum foil laminated paper, and the loss generated in the lamination process is naturally reduced, making it more economical. This is extremely advantageous.

Fifth, because the paper is laminated with barrier plastic or film on both sides, the stiffness is increased compared to paper or laminated paper that is laminated on one side.

The lid material for pressure-resistant containers as described above is made by first covering the front and back sides of a paper material made of a non-woven cloak with an anchor film such as polyethylene, then applying the whole thing with a hot pressure roll or heat press to form a flat plate with the anchor film adhered to the paper material. make a cloak. Thereafter, a barrier plastic film is placed on top of the anchor film, and the compressibility is reduced using a hot pressure roll, which is advantageous in terms of productivity and cost, and then pressed to form a flat cloak. Add this to another 150
The lid material was formed by press molding in two stages or one stage using a mold heat press at about °C.

However, the anchor coat film of the Anchor Foil 1-laminate nonwoven fabric cloak that is heat-pressed has many pinholes due to degassing of the air in the nonwoven fabric during heat pressing, and the barrier film melts and ruptures during press molding, resulting in pinholes. was generated, and furthermore, it was impossible to treat the burrs at the edges. , J) The occurrence of pinholes or the impossibility of barrier treatment as described above may cause carbon dioxide gas to permeate out of the container through these pinholes.

The present invention was invented in view of the above points, and the following method was adopted for the purpose of reducing the number of pinballs in the lid of a paper pressure-resistant container.

That is, this is a method of laminating a paper pressure container lid material, which is characterized by forming a paper material into a lid shape by compression molding, and then laminating a barrier plastic film on the inner and outer surfaces of the paper material by vacuum or pressure molding.

According to the method of the present invention, the barrier plastic film is laminated by vacuum or pressure molding after the lid is molded, and is not already laminated when the lid is molded, so pinballs do not occur. do not have. Further, since the 11:+ surface treatment is also performed at the same time, contact with the outside air is prevented.

The embodiments shown in the drawings will be described below.

The material for the paper pressure container lid material is a sheet of barrier plastic film/paper/barrier plastic film. Examples of the barrier plastic film include polyvinylidene chloride, vinylidene chloride-vinyl chloride copolymer, polyamide, and nylon. , polyester, polyvinyl alcohol, ethylene-vinyl acetate copolymer generator resin sold under the trade name "Epal" (Kuraray Co., Ltd.), cellophane, and even polyacrylonitrile rBAREXj (Vistron Co., Ltd.), r
It is a film made of nitrile resin sold under a trade name such as LOP A Cj (Monsanto).

The paper type is a non-woven cloak made of a mixture of paper pulp and synthetic pulp. That is, it is a nonwoven fabric cloak formed by a dry method from a mixed pulp containing 10 to 50% by weight of synthetic pulp. Here, the synthetic pulp refers to a thermoplastic resin that is in the form of fibers or split into chips using a fibrillator, etc. Examples of thermoplastic resins include polyethylene, polypropylene, polystyrene, blends of polyethylene and polystyrene, polystyrene and acrylonitrile/ It is a blend with styrene copolymer.

First, a method for simultaneously laminating barrier films on both sides of the above-mentioned paper material will be explained.

First, anchor films such as polyethylene are laminated on the front and back sides of the sheet made of the nonwoven fabric using a hot pressure bonding roll or a hot press.

Next, it is compressed using a hot press, and then formed into a lid shape using a hot press using a mold as shown in FIG. Here (11)
(12) is dl [divided into three parts to make it easier to take out the molded product (3) with the male mold.

Next, as shown in FIG. 2, barrier films (4) and (5) are set on a lid (3) formed on a net (2) that has been set in advance in a vacuum chamber (1).

Next, press the edge of the barrier film with a ring-shaped holding jig (6) having four grooves (6a) around the circumference as shown in 3.4 [1]. After that, the inside of the chamber (1) is evacuated through the valve (7), and the inside of the chamber (1) is evacuated.
) Heater with upper and lower sides (9) (10)
Heat it up.

In this case, the strength of the heater is adjusted so that the barrier films (4) and (5) are sufficiently softened when the inside of the chamber (1) becomes vacuum (10 ma+Hg or less, preferably 1+IIIHg or less). Alternatively, after the chamber is evacuated, the barrier film may be softened by heating with a heater.

Next, when air is introduced into the chamber (1) through the pulp (7), a molded body with a barrier film adhered to the lid surface is obtained as shown in FIG. The firmness formed in the molded object (
9) cant.

According to the method described above, the film is also laminated at the end of the lid.

The above method is a method in which a barrier film is laminated on both sides of a paper material at the same time, that is, a double-sided simultaneous method, but a method in which a barrier film is laminated on one side of a paper material at a time can also be adopted.

That is, a lid molded body is made in advance in the same manner as in the above method.

Next, as shown in Fig. 6, this was set on a mold (13) with four parts (13a) with the lid (3) facing upward, and the barrier film (4) was applied on top of the mold (13) using the jig described above. Press the l'ilA edge with (6).

This is set on the net (2) of the chamber (1). Similarly, the inside of the chamber (1) is evacuated through the pulp (7), and the heater (9) above the chamber (1) is evacuated.
). In this case, the lower heater (10) in the chamber (1) is not required.

The lid material (3) laminated with the Barrier i raw film (4) is turned over and molded into a mold (13) as shown in Figure 7.
Set it on top, cover it with a barrier film (5), and press the 6i:h edges with a jig (6).

The mold (13) is then placed in the chamber (
Just place it on the net (2) of 1) seven times and make the inside of the chamber a vacuum.

FIG. 8 shows the molded product, in which the edges of the film overlap each other and are laminated to the skirt portion of the lid. 1 In addition, when a non-woven fabric cloak made only of pulp fibers is used as a lid, the bond between the pulp fibers is weak when it is formed into a lid, so the strength is weak and it cannot be used as a lid for a pressure container. It is preferable to use a non-woven cloak formed by a dry process from a mixed pulp containing 10 to 50% by weight of synthetic pulp.

The non-woven cloak produced by the dry method has a weak bond between fibers and is easily slippery compared to paperboard, etc., so even if there is a deep-drawn part such as the skirt part that is used for bot press, the sheet will not be able to pass through the press. Since it is easily deformed along the inside of the mold, there is no risk of it tearing or wrinkling like paperboard.

Furthermore, when this nonwoven mat is heated and molded using a bot press, the mixed synthetic pulp melts and adheres to the pulp fibers, resulting in a molded product that has excellent mechanical properties such as tensile strength and rigidity, and is strong. Obtainable.

Further, as the pulp to be mixed into the non-woven mantle, a pulp having relatively long fibers is preferable in order to improve the strength of the molded article, and for example, bleached kraft pulp made of softwood is preferable.

The proportion of synthetic pulp mixed with the pulp that forms such a non-woven cloak is determined by the type and moldability of the synthetic pulp, the mechanical strength required of the molded product after molding, etc. It is important that most of the parts that come into contact with the required pressure fluid have a curved shape, and that the peripheral skirt part provided as necessary has formability and mechanical strength against carbon dioxide gas pressure. be. If the proportion of synthetic pulp is less than 10% by weight, the molded product will have poor mechanical strength due to weak bonds between pulp fibers, poor moldability, and a large drawing angle such as in the skirt part. Molding becomes difficult as wrinkles may occur in some areas or tearing may occur in some areas. On the other hand, if the proportion of synthetic pulp exceeds 50% by weight, although the moldability is improved, the excellent physical properties of paper, such as rigidity, are lost and mechanical strength becomes difficult. In view of the purpose of the present invention, which is to provide a pressure-resistant container that provides a pressure-resistant container, it is desirable to use as little synthetic pulp as possible. Therefore, the mixing ratio of the mixed pulp of synthetic pulp is 10 to 50% by weight, more preferably 20 to 40% by weight.

A method for producing a non-woven fabric cloak using a dry method is, for example, adding a certain amount of synthetic pulp to pulp, mixing and defibrating it in a dry state using a defibrating machine such as a dry refiner, and suspending this mixed fiber in the air. After that, it may be uniformly spread on a funomation wire equipped with a saccharide box to form a mat-like sheet.

The superiority of the device according to the present invention will be explained below using experimental examples.

Experimental Example 1 (1) Container structure As shown in Figure 9, the top and bottom lids have the same structure, but the top lid has an opening in the center, and a metal jig with a pressure gauge attached thereto is attached. and sealed.

(2) Body paper material: Weight 230 [! /= inside the bleached kraft paper tar, ? j Barrieron CX-28/Paper/Barrieroa CX
-28, barrier t:I 7'CX -28 is a product name manufactured by Asahi Kasei Corporation and is LDPE/PVDC/1. DPIi
It is a composite film.

(bl outer cylinder LDPE 50μ/paper/LDPE 50μ
Edge-treated film (tape) C in Fig. 11 is made of Varialon CX-28 (3), top cover, bottom cover, 50μ film on both sides of a non-woven mat with a weight of 11,200 g/m consisting of paper pulp 75W1'%, PE% synthetic pulp 25WT%. After the LDPE film was coated, it was hot pressed at a temperature of 150°C and a press pressure of 10 kg/cal. At this time, the nonwoven fabric mat was compressed to a thickness of 3 mm, and the LDPE film on the surface was firmly adhered to the nonwoven fabric cloak. Ta.

(Lid body of the present invention) The above-mentioned pressed product was punched into a disk with a diameter of 95 mm, and this was heated to 1
It was inserted into a mold at 50° C. to obtain a lid molded product having a spherical shell inner radius of 74 mm, a skirt portion length of 12 m, and a wall thickness of 1.5 mm.

Next, the inner and outer surfaces of the molded product were coated with Varialon CX-28 film by the method shown in FIG. 2 to obtain a lid of the present invention.

(Conventional lid body) After the Varialon CX-28 film is laminated on both sides of the flat press product, the same <95
A lid molded product was obtained by inserting the crane ψ into a punching mold and using the same method as the lid of the present invention.

The lid of the present invention and the conventional lid were fitted on the top and bottom of the body, and their joints were firmly bonded by heat welding.

Five containers each were prepared for the lid of the present invention and the conventional lid.

Next, each container was filled with a carbon dioxide gas-water mixture and then sealed using a metal jig for the top lid.

Table 1 shows the internal pressure of each container at this time and the internal pressure after 15B.

Note that the internal pressure is a value at a temperature of 25°C.

Table 1 (Unit: kg/kg) The results in Table 1 show that the effects of the present invention are extremely large.

Furthermore, it was assumed that the decrease in internal pressure in the conventional lid was caused by leakage due to pinholes generated in the barrier film during molding.

Experimental Example 2 (1) Container Structure The structure is as shown in Figure 10, except that an opening is provided in the center of the top lid. ! A mouth was attached. A metal jig with a pressure gauge attached to the opening is sealed several times.

(2) Body paper material double weight 230g/n (bleached kraft paper (al inner tube Varialon CX-28/Paper/Varialon CX-28 fbl outer ft?ILDPE 50μ/Paper/LDPE 5
0 μ (lid body of the present invention) (3) Bottom lid Same as the lid body of the present invention in Experimental Example 1 (4) Top lid Non-woven fabric cloak made of 75% paper pulp and 25% synthetic valve made of PR, weighing 1200 g/rd. 50 on both sides of
Temperature 150 °C after μ LDPE film coated,
It was hot pressed at a pressing pressure of 10 kg/crA.

At this time, the nonwoven fabric mat was compressed into the W fin and the LDPE film on the surface was tightly adhered to the nonwoven fabric cloak.

The above pressed product was punched into a disc with a diameter of 110 fins, and this was inserted into a mold at a temperature of 150°C, and the inner radius of the spherical shell part was 74 mm.
An upper lid molded product was obtained in which the skirt length was 12 mm, the inner diameter was 22 mm, and the opening had a wall thickness of 1.5 mm, having a lip with a length of 5 mm in the center.

Next, this upper lid was similarly covered with Varialon CX-28 film by direct air molding, and a PE mouth was attached to the opening to obtain the lid of the present invention.

(Conventional Lid) The container structure body etc. are the same as the lid of the present invention, except that the method of laminating Varialon CX-28 film to the lid is the conventional method of Experimental Example (1). However, the skirt portion of the upper lid Since the paper was exposed at the end, this part was covered with tape-shaped Varialon CX=28.

The lid of the present invention and the conventional lid were fitted on the top and bottom of the body, and their joints were firmly adhered by heat welding to obtain the container shown in FIG. 10.

Five containers were prepared each with the lid of the present invention and the conventional lid.

Next, each container was filled with a carbon dioxide-water mixture prepared to have an internal pressure of 2.5 kg/cig at 25° C., and the mouth was sealed with an aluminum cap.

The results of tracking leaks from each container under this condition were as follows.

The lid of the present invention was tracked for 15 days, but no leakage of carbon dioxide gas from the container was detected in 5 containers.

Conventional 51x body...Leaks occurred from the two lids between 1hv and 24hv after filling.

From the above, it can be seen that in the case of the upper lid, the occurrence of pin poles is extremely large in the conventional method.

It can be seen that the method of the present invention is extremely effective even for objects having such a top cover shape, and can also be applied to covering the exposed portion of paper at the end of the skirt portion at the same time.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view showing an example of a mold. Fig. 2 is a cross-sectional view of the interior of the vacuum chamber. Figs. 3 and 4 are slope views of the presser jig. Fig. 5 is the present invention obtained by the simultaneous double-sided method. Figures 6 and 7 are cross-sectional views of the molded product. Figure 8 is a cross-sectional view of the molded product obtained by the same method as above. Figures 9, 10, and 11 are longitudinal cross-sections of the container in the experimental example. They are a side view and a cross-sectional view. (1)...Vacuum chamber (2)...
・Non, G (3) ... Lid material (4) (5) ... Barrier film (6) ...
・・Pressure tool

Claims (1)

[Claims] A method for laminating a lid material for a pressure-resistant container made of paper, which comprises forming a paper stock into a lid shape by compression molding, and then laminating a barrier plastic film on the inner and outer surfaces thereof by vacuum or pressure molding.