JPS61190439A - Three-dimensional plastic packaging container that is easy to heat - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a three-dimensional packaging container that can be easily heated.
More specifically, the present invention relates to a three-dimensional packaging container in which heating operations such as heat sterilization of the contents and heating of the contents before meals can be easily performed.

Metal cans have almost perfect sealing properties and gas barrier properties.
Although it has been used for many years as a packaging container with excellent shape retention, in recent years, it has become difficult to dispose of it, leading to the problem of so-called can pollution.

As an alternative to metal cans, various three-dimensional packaging containers made of plastic have become widely used in recent years. However, the biggest drawback of three-dimensional plastic containers is that plastic has low thermal conductivity. ,
Therefore, the container wall acts as a heat transfer barrier, and when heating the contents for heat sterilization or eating, it takes an extremely long time. Special Publication No. 58-35458 and No. 59-1 as a plus container
Publication No. 8263 proposes a metal foil laminate that is wrapped and pasted around the outer peripheral surface of a plastic body with openings at both ends, and a lid body is engaged with the openings at both ends and sealed by heat sealing. There is. Although this composite container has an excellent combination of shape retention due to the plastic body and gas barrier properties due to the metal foil laminate, the thickness of the plastic body that provides shape retention to the container does not allow the container to move in the cross-sectional direction. The heat conduction of the container becomes extremely poor (retort sterilization) and heating of the contents during consumption requires an extremely long time.

OBJECTS OF THE INVENTION Accordingly, an object of the present invention is to provide a three-dimensional plastic packaging container that overcomes the above-mentioned drawbacks of conventional plastic containers.

Another object of the present invention is to provide a three-dimensional packaging container made of plastic that has excellent thermal conductivity and can be easily heated.

Still another object of the present invention is to provide a three-dimensional plastic packaging container that is easily heated and is formed from a thermoplastic resin containing metal fiber staples and in which the metal fiber staples are protected from corrosion.

Structure of the Invention According to the present invention, there is provided a three-dimensional packaging material that is easy to heat and is characterized by comprising at least one layer of thermoplastic resin containing metal fiber staples having an aspect ratio (l/d) of 2 or more. A container is provided.

According to the present invention, the present invention also comprises a base layer made of a thermoplastic resin blended with metal fiber staples having an aspect ratio (l/d) of 2 or more, and a protective resin layer located at least on the inner surface of the base layer. A three-dimensional packaging container that can be easily heated is provided.

Features and Effects of the Invention The present invention provides that when metal fibers having an aspect ratio in a certain range, that is, in a range of 2 or more, are blended into a thermoplastic resin, thermal conductivity as high as 12 can be obtained with a relatively small blending ratio. This knowledge will be applied to three-dimensional plastic containers.

The thermal conductivity of metal is extremely high compared to resin (2~
(3 digits), the thermal conductivity of the resin composition containing metal as a filler is also greatly improved. The thermal conductivity of this blended composition is greatly influenced by the metal filling rate (mixing ratio) as well as the aspect ratio (ratio of length 1> to diameter Cd) of the metal filler, and the relationship can be expressed by the formula: , as shown in the following formula.

k=, (1+ABφt)/(1-Bψφ2)A=f
l t/d I B = (kt/ k+ 1) / (, 7, / to 8 A) ψ=10 [I(1-φm)/φ-]φ.

However, k: thermal conductivity of metal filler-filled thermoplastic resin,
: Thermal conductivity of thermoplastic resin, : Thermal conductivity l/d of metal filler : Aspect ratio φ of metal filler, : Filling ratio φm of metal filler: Closest packing ratio of metal filler Also, A=f l l The value of /d1 is as shown in Table 1, and φ□ is 0.5 in the case of non-oriented fibrous filler.
It is 2.

From the above equation, it is clear that when metal fibers with a large aspect ratio are blended into the resin, the thermal conductivity can be significantly improved with a relatively small amount of blending.

According to the present invention, by using the resin composition blended with the above-mentioned metal fiber staples as a material constituting the container wall of the three-dimensional container, the thermal conductivity of the container wall is increased, and the The advantage is achieved that heating can be easily carried out within a relatively short time. Moreover, since the metal fiber staple blended into the resin is of course a good conductor of electricity (-), it has the advantage that the above-mentioned heating can be carried out easily and efficiently by high-frequency heating.

Furthermore, the metal fibers blended into the resin have the advantage of increasing the rigidity of the blended composition to the limit required for three-dimensional containers, increasing the heat distortion temperature of the container, and improving the heat resistance of the container.

In a preferred embodiment of the present invention, a resin layer containing metal fibers is used as a base layer, and a pupil-keeping resin layer containing no metal fibers is provided on at least the inner surface, preferably both surfaces, of this base layer. Although metal fibers have the above-mentioned advantages, they have the disadvantage of being inferior in corrosion resistance compared to resins, but according to this preferred embodiment of the present invention, protective By providing the resin layer, it is possible to prevent the occurrence of corrosion such as rust on the metal fibers and the elution of Kanejima substances into the contents, and also to significantly improve the appearance characteristics of the container wall.

The present invention will be described in detail below with respect to its embodiments.

Embodiments of the Invention In the present invention, metal fibers obtained by any method known per se such as melt spinning, stretching, extrusion, cutting, chatter vibration cutting, etc. are used. The type of metal constituting the fiber may be any metal such as steel, cast iron, stainless steel, brass, copper, aluminum, etc., and is expressed by the formula t/ri (where t is the length of the metal fiber and d is the metal It is important for the purposes of the present invention that the aspect ratio, defined as the diameter of the fibers, is greater than or equal to 2, more preferably in the range from 10 to 5,000.

In other words, when the amount of metal fibers to be blended is set to a constant value in a relatively low range and the aspect ratio of the metal fibers is changed, the thermal conductivity of the blended resin composition suddenly increases beyond the standard aspect ratio. It shows a tendency to This is thought to be because when the aspect ratio of the filled metal fibers exceeds a reference value, they come into almost uniform contact within the matrix, forming a stable heat conduction path.

Suitable metal fibers have a diameter of 1 to 1000 μm1.
In particular, the staple length is 5 to 100 μm, and the staple length is 0.
．． 1 to 1000 mm, especially 0.5 to 100 mm.

The resin in which the metal fibers are blended may be any thermoplastic resin that can be thermoformed, such as low-1 medium- or high-density polyethylene, crystalline polypropylene, crystalline ethylene-propylene. Olefin resins such as copolymers, propylene-butene copolymers, and ionically crosslinked olefin copolymers; Styrenic resins such as polystyrene, styrene-butadiene copolymers, and styrene-butadiene-acrylonitrile copolymers; Polycarbonates: Polyester: polyamide; acrylic resin; polyacetal resin, etc. are used. Among these, olefin resins are preferable from the point of view of economy and ease of production, and polypropylene is the most preferable from the point of view of retort sterilization. The amount of metal fibers added to the thermoplastic resin depends on the aspect ratio of the metal fibers. Although it differs depending on the size and diameter, it is preferably within the range of 1 to 60 volume units, particularly 5 to 40 volume units based on the resin. That is, if it falls below this range, no significant improvement in thermal conductivity can be expected, while if it exceeds the above range, the thermoformability into containers will deteriorate and the mechanical properties of the containers will also deteriorate. .

Mixing of resin and metal fibers is a triblend 1-
1. If necessary, this can be easily carried out by kneading this mixture under conditions in which the resin is melted. The kneading operation may be performed using, for example, a roll, kneader, pelletizer, etc.
It can also be carried out in a cylinder such as an extruder or an injection machine.

The three-dimensional packaging container according to the present invention can be manufactured by means known per se, except for using the metal fiber-containing resin described above. In addition, the container itself may be a single-layer container made of a resin composition containing metal fibers, or a laminated container consisting of a layer of a resin composition containing metal fibers and another resin layer and/or a metal foil layer. It's actually good.

For example, the container can be formed by melt-extruding the composition into a parison and then blow-molding it into a bottle shape, or by directly injecting it into a mold with a container-shaped cavity. can also be done. Furthermore, a cup-shaped container with a bottom can be made by preparing a sheet of the above-mentioned composition and subjecting this sheet to vacuum forming, pressure forming, plug assist forming, stretch forming, or the like. Alternatively, a pipe or a preform with a bottom is once formed by extrusion or injection, and the pipe or preform with a bottom is subjected to tensile stretching in the axial direction and expansion stretching in the circumferential direction at the stretching temperature of the resin. Accordingly, it is also possible to obtain a container in which the resin matrix has molecular orientation in biaxial directions. Furthermore, the composition can be melt-extruded into a pipe shape and cut into a predetermined size to form a container body with both open ends sealed.

In FIGS. 1 and 2 showing an example of the container of the present invention,
This container consists of a seamless body 1 and both open ends 2. It consists of lid bodies 4a and 4h that are applied to B. This torso 1V
i. A matrix 5 made of a thermoplastic resin formed from the resin composition described above, as shown in the enlarged cross-sectional view of FIG.
and metal fiber staples 6 dispersed in this matrix.

A lining of a metal foil-containing laminate generally indicated by 7 is formed on the inner surface of the body 1 made of metal fiber-containing resin.

As is clear from the cross-sectional view in Fig. g2, the laminate layer 7 applied to the inner surface of the cylindrical body 1 consists of a metal foil 8, a heat-sealable resin layer 9 on the inside of the metal foil, and a resin layer on the outside of the metal foil. layer 1
It consists of 0 laminates.

The laminate layer 7 is applied to the inner surface of the cylindrical body 1 in the form of a sheet having a size larger in the lateral direction than the unfolded dimension of the cylindrical body 1, and the seam 7' is formed by overlapping both ends of the laminate layer 7.
is formed.

The lids 4α, 4b are fixed to the open ends 2, 6 of the container body by means known per se, such as heat sealing, seaming, adhesion, or the like.

The thickness of the body part 1 is set so that sufficient shape retention is obtained.
It is desirable that it be within the range of about 0.2 to 2 rran.

In FIG. 6, which shows another laminate suitable for forming the container of the present invention, this laminate 11 has a base layer 12 made of a resin composition containing metal fibers, and a base layer 12 made of a metal fiber-containing resin composition, and metal fibers applied to both surfaces of the base layer 12. It consists of unblended protective resin layers 13 and 147. The protective resin layers 16 and 14 are preferably made of a resin that has thermal adhesive properties to the resin layer constituting the base layer 12.
Most preferably, the protective resin layers 13 and 14 are of the same type as the resin layer constituting the base layer 12. The protective resin layers 13 and 14 have a thickness of 1/1 of the thickness of the base layer 12.
00 to 115 in thickness and 6 to 4 in final container shape.
A thickness of 00 μm, particularly 5 to 100 μm, is desirable in order to prevent metal corrosion and metal elution without sacrificing excellent thermal conductivity.

This type of laminate can be easily formed by coextruding a metal fiber-containing resin composition and a resin without metal fibers through a multi-layer die, and by using this laminate, as shown in FIG. A hollow-molded container such as a bottle, a pipe-shaped container body, and a bottomed cup-shaped container having a cross-sectional shape of .

Alternatively, between resin films without metal fibers,
A laminated sheet used for vacuum forming or the like can also be easily obtained by extruding a metal fiber-containing resin melt and performing so-called sandwich lamination.

In this laminated structure container of the present invention, the exposure of metal fibers to the outer surface is effectively prevented, and significant advantages are achieved in terms of appearance characteristics and corrosion prevention, as well as surface smoothness, heat sealability, and hygiene. physical characteristics etc. are also improved. Especially the protective resin layer 13
And 14, when a pigment such as titanium dioxide, iron oxide, zinc oxide, barium sulfate, calcium carbonate, etc. is blended, the gold M fiber blend layer is hidden, and the appearance characteristics are further improved.

The invention is illustrated by the following example.

Examples 1 to 4 The thermoplastic resin and metal fiber shown in Table 2 were mixed using a two-roll calender roll mill at the same filling rate shown in Table 2, and the metal fibers were uniformly dispersed (- A composite material was obtained.

Next, using the metal fiber optic fli composite material, an inner diameter of 5
Extrude a 2.3m pipe with a wall thickness of 0.6rrra, 1
Cut to 65-mm length.

Furthermore, a graft-polymerized modified polypropylene resin powder (melting point 160 tl) was coated on aluminum foil with a thickness of 15 μm so that maleic anhydride became a polymer with a carbonyl group concentration of 14[]q/100, and melt-rolled ( The average film thickness was 7 .mu.m to form a fiat film.

Furthermore, after laminating polyethylene terephthalate with a thickness of 12 μm on the aluminum foil surface of the fII layer body using a urethane adhesive, a copolyester resin was applied thereon with a thickness of 30 μm by extrusion coating to form a laminated layer for inner surface coating. I prepared my body.

Next, the laminate is slit at an end with a length of 135a + a width of 175, and one end is folded 5-fold in the width direction so that the polypropylene layer is on the inside to form a folded part 17, thereby forming a laminate notebook. It is wound on a mandrel so that the folded part faces outward, and one end of the folded part 1 and the other end are overlapped to form a cylindrical laminate, and this cylindrical m
The polypropylene pipe was fitted onto the outside of the cylindrical laminate on the outside of the circumferential body.

Next, the diameter of the mandrel is expanded outward, and while the cylindrical laminate is pressed against the inner surface of the pipe, the laminate is simultaneously heated and bonded to large pieces of plastic and metal using a high-frequency heating coil provided on the outer periphery of the mandrel. A foil composite can was fabricated.

A 5 μm epoxy phenol resin/10
The lid and body were thermally fused by high-frequency induction heating of a lid material having a score and a tab of a liquid portive made of a laminate of 0 μm aluminum foil, 712 μm polyethylene terephthalate/20 μm copolyester. Fill the plastic fly with the lid attached with 250ml of coffee,
A lid having the same structure as the lid was heat-bonded to the opening in the same manner.

The sealed can thus obtained was heated and sterilized in a hot water retort at 125C for 1 minute at 2r.1. Ta.

For Example 1, the F0 value (heating time [minutes] required to kill a certain concentration of bacteria or spores at a certain temperature) of the center of the coffee was measured, and it was 1167, indicating that the sterilization conditions were sufficient. Ta.

Moreover, when the top lids of Examples 1 to 4 were opened and the coffee was sampled, the flavor was very good, and no off-taste or odor was observed.

Example 5.6 In Example 1, the composite material shown in Table 2 was used as the pipe material (-1 Instead of the maleic anhydride-modified polypropylene of the inner coating laminate, nylon 6 (melting point 215C1 density 1.14R) was used. /c111, relative viscosity 2.3) was laminated by the extrusion coating method, but a plastic/gold foil composite can was produced in the same manner as in Example 1.

The plastic/metal foil composite can thus obtained was filled with coffee in the same manner as in Example 1, resulting in 125 tons of coffee. When the center part of the coffee of Example 6 was subjected to 20 minutes of hot water retort heat sterilization, the value of the coffee in the center was 16.2, indicating that the sterilization conditions were sufficient.

In addition, when the top lids of Examples 5 and 6 were opened and the coffee was sampled, the flavor was very good, and no off-taste or odor was observed.

Comparative Example 1 In Example 1, only polypropylene, which is a matrix resin, was used as the pipe material.The material was filled with coffee and subjected to heat sterilization in a hot water retort for 125 [20 minutes.About this bookCoffee When the Fo value of the center was measured, it was found that the sterilization conditions for coffee were insufficient at z8.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a container using the thermoplastic resin containing metal fiber staples of the present invention, and FIG. 2 is a cross-sectional perspective view showing an enlarged cross-section of the cylinder shown in FIG. FIG. 6 is a cross-sectional perspective view of a laminate used for a container which is another specific example of the present invention. Side lighting code 1 is a seamless body, 2 and 6 are both open ends 4α and 4b are lids, 5 is a matrix resin, 6 is a metal fiber staple, 7 is a metal foil-containing laminate, 8 is a metal foil, and 9 is a 10 is a metal foil outer resin layer, 11 is a laminate, 12 is a resin composition containing metal fibers, and 13 and 14 are protective resin layers. 1st table Spherical 1150 Fibrous (non-oriented) 2 1.58
4 2.08 6 2.80 10 4.9ro15 8.38 35 30.0 50 60.0 Figure 1 Figure 3 Hand Itotari Amendment (method) % formula %) 0 Name of the invention Easy to heat Three-dimensional plastic packaging containers), Relationship with the person making the amendment (2) 19 cases Patent applicant 1, agent 〒105 ・Date of amendment order May 28, 1985 (shipment date), Subject of amendment ■ 2 Column for detailed description of the invention (1) Attachment 1 between lines 7 and 6 from the bottom of page 5 of the specification
Adding a table (2) Next to page 17, line 15, add the second table. 4. Brief description of the drawings (1) Table 1 on page 18 of the specification will be deleted. (2) Table 2 on page 19 will be deleted. Table 1 Table 2

Claims (2)

[Claims] (1) A three-dimensional packaging container that is easy to heat and is characterized by comprising at least one layer of thermoplastic resin containing metal fiber staples having an aspect ratio (l/d) of 2 or more. (2) Heating characterized by comprising a base layer made of a thermoplastic resin blended with metal fiber staples having an aspect ratio (l/d) of 2 or more, and a protective resin layer located at least on the inner surface of the base layer. Three-dimensional container for easy packaging.