JPH01139336A - Composite paper container - Google Patents

Abstract

PURPOSE:To obtain a composite paper container whose bonding areas are firmly adhered together, by adhesively attaching the bonding areas of a lamination layer material having a heat sealable polyester resin with a heat adhesive agent. CONSTITUTION:A lamination material 1 of which a composite paper container is formed of the innermost layer of a heat sealable polyester resin 11, the outermost layer of polyolefin resins 12 and the intermediate layer of a paper composite base material 13, these lamination materials being simply superposed and the bonding areas being coated with an adhesive agent 2. In this case, polyamide and acryl resins, etc., are used as an adhesive agent excellent in the heat adhesiveness to the polyester resin. The heat sealing of such bonding areas with the adhesive agent excellent in the heat adhesiveness to the polyester resin imparts a large adhesive strength of the bonding areas. The innermost layer of this container being the polyester resin layer, the harmful effects such as the loss of the savor of contents or the occurrence of an offensive odor are eliminated.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a paper composite container formed by an envelope pasting method, and in particular, the innermost layer is a polyester resin layer having heat-sealability and the outermost layer is a polyolefin resin layer. The present invention relates to a paper composite container made of a laminated material with a bonded portion firmly adhered.

[Conventional technology]

Conventional laminated materials used for packaging bags, etc., as well as the bodies, bottoms, and lids of containers for storing various liquid foods, drinks, tea, and spices, have polyolefin resin layers on both surface layers. These polyolefin resin layers are used to form containers and packaging bags of various shapes by taking advantage of their thermal adhesive properties.

However, it has been found that when the conventional laminated material in which both surface layers are composed of polyolefin resin layers is used as, for example, a container body, a container bottom material, a container lid material, etc., the following problems occur. That is, when a polyolefin resin layer is formed or a container or packaging bag is formed using the laminated material, the polyolefin resin undergoes thermal decomposition and generates volatile components such as aliphatic hydrocarbons. As a result of migration into the contents contained in the packaging bag, the contents develop an odd taste or odor. Furthermore, the polyolefin resin layer in the laminated material has the disadvantage that the flavor of the contents is lost because the polyolefin resin layer easily adsorbs or easily permeates the young components in the contents.

Therefore, in order to eliminate the above-mentioned drawbacks of polyolefin resin layers, we used a laminated material with polyester resin layers on the inner and outer layers that generate less volatile substances and have good heat-sealing properties and aroma retention. It is possible that

[Problem that the invention seeks to solve]

However, if both sides of the laminate are made of polyester resin layers having heat sealability, the cost will be high. Additionally, changing the surface layer from a polyolefin resin layer to a polyester resin layer also poses a problem in that the ink for surface printing of the paper composite container and other processing conditions must be changed. Further, even when a container is formed using a laminated material whose innermost layer is a polyester resin layer having heat-sealing properties, there is a problem in bonding the laminated material. That is, it is necessary to bond the polyolefin resin layer of the inner laminate to the polyester resin layer of the outer laminate, but the adhesion between the two is generally not good.

Therefore, an object of the present invention is to provide a polyester resin layer in which the innermost layer is made of a polyester resin layer having heat-sealing properties, which can be firmly bonded without complicating the structure of the bonded part;
An object of the present invention is to provide a paper composite container whose outermost layer is made of a polyolefin resin layer.

[Means for solving problems]

In view of the above problems, as a result of intensive research, the present inventors have developed a method of applying thermal adhesive to a polyester resin having heat sealability in the bonding area where the polyolefin resin layer of the laminated material and the polyester resin layer having heat sealability are joined. By applying adhesive with adhesive properties and heat sealing,
The inventors discovered that a paper composite container can be easily formed and came up with the present invention.

That is, the paper composite container of the present invention is made of a laminated material in which the innermost layer is a polyester resin layer with heat-sealability and the outermost layer is a polyolefin resin layer, and the bonded portion of the laminated material is made of a polyester resin with heat-sealability. It is characterized in that it is bonded via an adhesive that has thermal adhesive properties to.

In the present invention, the polyester resin layer having heat-sealing properties constituting the paper composite container has a softening point of 60 to 2.
A thermoplastic polyester resin having a temperature of about 40°C is used, preferably polyethylene terephthalate (softening point: 80°C). Polyesters in a highly crystalline state are generally not preferred because they have a high softening point, and polyesters in a low crystalline state or amorphous polyesters are preferred. The polyester resin layer has the function of sealing the laminated material by heat-sealing and also preventing seepage and leakage of the contents, and generally has a thickness of 3 to 150 μm. Further, the polyolefin resin layer imparts water resistance to the surface of the laminated material, and polyethylene, polypropylene, etc. can be used, and the thickness is generally about 3 to 150 μm.

As the paper composite base material, a paperboard having a thickness corresponding to the shape and size of the container is used, and aluminum foil is pasted if necessary. The thickness of paper composite substrate is generally 40-1000μ
It is m.

In the bonding part of the laminated material, the polyolefin resin layer (outermost layer) at one end and the polyester resin layer (innermost layer) at the other end are bonded, so an adhesive with good thermal adhesion properties is used for both. It is necessary to use it. However, since polyolefin resins generally have good thermal adhesiveness, it is sufficient to select an adhesive that has good thermal adhesiveness with polyester resins having heat-sealing properties.

Such adhesives include polyamide resin, acrylic resin, polyvinyl chloride, vinyl chloride/vinyl acetate copolymer resin, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral (butyral resin), chlorinated polypropylene, styrene resin, and epoxy resin. , polyurethane, cellulose derivatives, polyester resin, phenolic resin,
Xylene resin, urea resin and melamine resin, ketone resin, coumaron/indene resin, petroleum resin, terpene resin,
One or more resins such as cyclized rubber, chlorinated rubber, alkyd resins, natural resins, and natural resin derivatives are combined with aliphatic hydrocarbons, aromatic hydrocarbons, alcohols, esters, ketones, glycols, 1 of solvents such as glycol derivatives
Use seeds or a mixture of two or more. Other,
It is also possible to apply an adhesive polyester resin or an adhesive polyolefin resin as an adhesive by extrusion coating or a hot melt applicator.

The adhesive polyester resin has ethylene glycol and terephthalic acid as its main components, and if necessary, polyhydric alcohol, long chain glycol, etc. may be used instead of ethylene glycol, and isophthalic acid,
Those synthesized using aliphatic dicarboxylic acids, aromatic dicarboxylic acids, etc. can be used.

Examples of the adhesive polyolefin resin include polyethylene, ethylene-α-olefin copolymer, polypropylene, polybutene, and polyα-olefin such as polyisobutylene.
In addition to olefins, polydiolefins such as polybutadiene and polyisoprene, or copolymers thereof, ethylene and ethylenically unsaturated monomers such as carboxylic acids, carboxylic acid salts, carboxylic acid anhydrides, carboxylic acid esters, etc. Carboxylic acid amide or imide, and monomers having a carbonyl group based on aldehyde, ketone, etc., alone or in combination with an ano group, a hydroxy group, an ether group, an epoxy ring, etc.). These are polymers, etc., and specific examples include the following.

A, ethylenically unsaturated carboxylic acid, acrylic acid, methacrylic acid, maleic acid, fumaric acid, crotonic acid, itaconic acid, citraconic acid, 5-norbornene-2,3-dicarboxylic acid, etc.

B, ethylenically unsaturated carboxylic anhydride, maleic anhydride, citraconic anhydride, 5-norbornene-2,3-dicarboxylic anhydride, tetrahydrophthalic anhydride, and the like.

C, ethylenically unsaturated ester ethyl acrylate, methyl methacrylate, acrylic acid 2
-Ethylhexyl, mono- or diethyl maleate, vinyl acetate, vinyl propionate, propyl T-hydroxymethacrylate, ethyl β-hydroxyacrylate, glycidyl acrylate, glycidyl acrylate, β-N
-ethylaminoedyl acrylate, etc.

D, ethylenically unsaturated amide or imidoacrylamide, methacrylamide, maleimide, etc.

E, ethylenically unsaturated aldehyde or ketone acrolein, meccrolein, vinyl methyl ketone, vinyl butyl ketone, etc.

Among these, ethylenically unsaturated carboxylic acids or ethylenically unsaturated carboxylic anhydrides are particularly preferred.

Adhesive is 0.5 to 20μ in the bonded part of the laminated material.
Preferably, the coating is applied to a thickness of m. Adhesive thickness is 0.
If it is less than 5 μm, the adhesive strength is insufficient, and if it is less than 20 μm,
If it exceeds m, the adhesive will protrude when the bonded parts are crimped. The preferred adhesive thickness is 1 to 10 μm.
It is.

Thermal bonding with an adhesive can be performed by conventional heat sealing, and is generally performed at a temperature of 80 to 240°C.

〔Example〕

FIG. 1 is a sectional view showing a paper composite container according to an embodiment of the present invention.

The laminated material 1 forming the paper composite container has an innermost layer of a polyester resin layer 11 having heat sealability, an outermost layer of a polyolefin resin layer 12, and an intermediate layer of a paper composite base material 13. In this embodiment, the laminated materials 1 are simply overlapped, and an adhesive 2 is applied to the bonded portion.

FIG. 2 shows a paper composite container according to another embodiment of the invention.

In this embodiment, the inner end of the laminate 1 is covered with a tape 3. Since the tape 3 is exposed on the inside of the container, it is necessary to have a polyester resin layer having heat-sealing properties as the outermost layer 31. Further, the innermost layer 32 of the tape 3 is preferably formed of a polyolefin resin with good heat sealability.

FIG. 3 shows a paper composite container according to yet another embodiment of the invention. In this example, the polyolefin resin layer 12 at the end of the inner layered material 1 is removed and the end is folded over (skive hemming method). This prevents the end of the laminate 1 from being exposed inside the container.

The present invention will be explained in further detail by the following examples.

Example 1 A laminated material was formed in order from the outermost layer to have the following configuration.

(1) Polyolefin resin layer with a thickness of 30 μm - “Mirason 16PJ (manufactured by Mitsui Petrochemical Industries ■) (2) Basis weight 40
0 g/m' heat-resistant paper (3) 15 μm thick ionomer resin layer - [HIMILAN 1652J (manufactured by Mitsui DuPont Polychemicals) (4) 9 μm thick aluminum foil (5) 12 μm thick biaxially stretched polyethylene terry cloth Crate film (6) Three-layer coextruded film with a thickness of 60 μm and the following configuration:
(a) 1130 μm ethylene-α-olefin copolymer layer - “Urtzex 2020 LJ (manufactured by Mitsui Petrochemical Industries Ltd.) (b) 10 μm thick adhesive polyolefin resin layer”
Atomer AT469CJ (manufactured by Mitsui Petrochemical Industries ■) (C) Linear saturated polyester resin layer with a thickness of 20 μm-r
PETG 6763J (manufactured by Eastman Kodak Company) In this way, the innermost layer becomes a polyester resin layer having heat sealability.

An adhesive polyolefin resin (Atomer A T469C) was applied as an adhesive to the bonded portion of the laminated material having the above structure by heating and melting it at 80° C. using a hot melt applicator. Next, the bonded portion was thermocompression bonded at 160° C. and heat sealed.

The bonding strength of the paper composite container thus obtained was 3.
．． It was large at Okg/m'.

〔Effect of the invention〕

As described above, the paper composite container of the present invention uses a laminated material having a heat-sealable polyester resin layer on the inside, coats the bonded part with an adhesive that has good thermal adhesion to the polyester resin, and heat-seals the container. The strength of the bonded part must be high. In addition, by making the innermost layer of the paper composite container a polyester resin layer with heat-sealing properties, the negative effects of causing the contents to have a strange taste or odor that occur with conventional paper composite containers made of polyolefin resin are eliminated. Ta.

Further, since the outermost layer of the paper composite container having the envelope pasting portion is made of a conventional polyolefin resin during formation, there is no need to change the ink when offset printing is performed on the outermost layer.

Furthermore, rather than making the outermost layer a polyester resin layer with heat-sealing properties, applying tape to the envelope pasting area requires less polyester resin and fewer changes to conventional molding, processing, and printing methods. Because it is fine,
Cost can be reduced.

The present invention can be applied to brick type paper composite containers, gobel top type paper composite containers, cylindrical paper composite containers, etc.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a paper composite container according to one embodiment of the present invention, and FIG. 2 is a cross-sectional view showing a paper composite container in which the ends of the inner laminate are covered with tape according to another embodiment of the present invention. FIG. 3 is a cross-sectional view of a paper composite container in which the ends of the inner laminate are skive-hemmed according to yet another embodiment of the present invention. 1... Laminated material 2... Adhesive 11... Polyester resin layer having heat sealability 12... Polyolefin resin layer 13... Paper composite base material

Claims (1)

[Claims] In a paper composite container made of a laminated material in which the innermost layer is a polyester resin layer having heat-sealing properties and the outermost layer is a polyolefin resin layer, the bonded portion of the laminated material has thermal adhesiveness to the polyester resin having heat-sealing properties. A paper composite container characterized in that the paper composite container is bonded with an adhesive having the following properties.