JPH03202340A - Preparation of laminate - Google Patents

Abstract

PURPOSE:To obtain an inexpensive laminate excellent in processability and having sufficient adhesive strength by together extruding a polyester resin, an adhesive resin and polyolefin under a specific temp. condition and blowing ozone gas to polyolefin to bond the polyolefine layer to a base material under pressure. CONSTITUTION:It is necessary to perform co-extrusion at 300 deg.C or lower and, when co-extrusion is performed at 300 deg.C or higher, materials become unsuitable for a beverage container by the oxidation smell of polyethylene or the like. Ozone gas is blown the region from the outlet 4 of a T-die to the press bonding part 5 of a cooling roll but the concn. thereof is pref. 1g/m<2> or more and the blow amount thereof is pref. 0.5 Nm<3>/hr per the width of 500mm of a molten film. For example, a base material 22 mainly consists of a paper base 12, the metal foil 14 provided through an ionomer layer 13 and the biaxially stretched polyester layer 15 provided thereon and, if necessary, an adhesive or primer coat layer 6 is provided thereon. A heat-sealable polyester resin is pref. used as the polyester resin constituting a co-extrusion polyester layer.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for producing a laminate, and more particularly to a method for producing a laminate suitable for constituent materials of beverage containers and the like by coextrusion.

[Prior Art] Beverages such as alcoholic beverages and whiskey have a high permeability into the materials that make up the containers. Conventionally, the materials for such beverage containers include paper with an ionomer layer or the like to prevent the permeation of beverages. Therefore, those equipped with metal foil such as aluminum were used. However, when such metal foil is used, there is a problem in that the metal foil cracks, particularly at the folded portions of the container, and to prevent this, a two-wheel stretched polyester film is usually provided on the metal foil. Furthermore, in the case of such beverage containers, because of their hygienic properties, water resistance, moisture resistance, and heat sealability, conventionally the above-mentioned two-wheeled stretched polyester film, that is, the portion that constitutes the inner surface of the container, has been coated with polyolefins, etc. Processed products were used.

However, when using the above-mentioned constituent materials, there is a problem that the original aroma, taste, etc. of the drink cannot be maintained because polyolefin has the property of adsorbing or permeating the flavor components of the drink. When produced by extrusion coating of polyolefin, oxidation is likely to occur, which also causes the problem of generating an unpleasant odor.

In order to solve the above problems, in recent years polyester has been used instead of polyolefin as a constituent material for the containers.

[Problems to be Solved by the Invention] For example, JP-A No. 1-139337 describes an example in which a biaxially oriented polyethylene terephthalate film is coated with a polyester resin and an adhesive polyolefin resin by coextrusion.・Meandering is large and processability is poor, and the adhesion between the two-wheel stretched polyester film and the adhesive polyolefin resin is small, so the base material and the inner surface cannot be sufficiently bonded, and the adhesive polyolefin A4 resin Since the cost of the laminate is high, the cost of the laminate is also high, resulting in problems such as limited applications. Therefore, a method for producing a laminate that satisfies the above requirements and is inexpensive has been desired for a long time.

Accordingly, an object of the present invention is to provide a method for manufacturing a laminate having small meandering/neck-in, excellent workability, sufficient adhesive strength, and low cost.

[Means for Solving the Problems] In view of the above problems, the present inventors have conducted extensive research and found that the above object of the present invention is to co-produce a polyester resin, an adhesive resin, and a polyolefin at a temperature of 300°C or less. It has been found that this can be achieved by a method for producing a laminate, which is characterized by extruding and blowing ozone gas onto the surface of the polyolefin layer in a molten state, and then pressing the polyolefin layer surface and the base material to form a laminate.

In this case, it is preferable that an adhesive or a primer coat material be applied to the base material as necessary.

The present invention will be explained in more detail below.

FIG. 1 is a schematic process cross-sectional view showing one example of the method for manufacturing a laminate of the present invention. According to FIG. 1, polyester resin,
The adhesive resin and the polyolefin are each melted in an extruder and merged before 114 in the T-die or immediately after the T-die, forming a three-layer molten film in this lamination order and co-extruded from the T-die. However, this coextrusion must be carried out at a temperature of 300°C or lower, preferably 200 to 300°C.
More preferably, the reaction is carried out at a temperature of 250 to 280°C.

If the process is carried out at a temperature higher than 300℃, polyethylene etc. will be oxidized and produce an oxidized odor, making it unsuitable for use as a material for beverage containers.If carried out over a long run, the polyester will partially decompose, resulting in deterioration of physical properties and reduction in heat sealability. etc., which is not desirable.

Ozone gas 2 is blown onto the surface of the coextruded molten film, that is, the surface of the polyolefin film in a molten state, at a step (hereinafter referred to as "air gap") midway from the T-die outlet 4 to the cooling roll crimping section 5. In this case, the concentration of ozone gas is preferably 1 g/f or more, especially 5 to 20 Q
/f is preferable. Also, the amount of ozone sprayed was 0.5N 1"/h for the molten film's radius of 500111
It is preferably r or more, and more preferably 1 Nm'/11
It is preferable that it is r~5Nr/hr. The temperature of the extruded resin during ozone spraying is 200-300℃ due to the above-mentioned reasons.
The temperature is preferably 250 to 280°C, and more preferably 250 to 280°C.

Next, the ozone-treated polyolefin film surface and the base material 6 are pressed together and cooled to obtain a laminate 9.

Figures 2 to 4 are each a preferred coextrusion method.
These are schematic partial process diagrams showing examples, in which FIG. 2 shows the method using the pre-die convergence feedblock method, FIG. 3 the in-die confluence multi-manifold method, and FIG. 4 the ex-die confluence multi-slot method. That is, in FIGS. 2 to 4, polyolefin, adhesive resin, and polyester resin are each melted in extrusion 1110 and fed into feed block 1.
1 and extruded from T-die 2. At this time, in Fig. 2, the above three molten resins are combined at the X part of the feed block section in front of the die, and then extruded from the T-die, and in Fig. 3, the three molten resins are combined at the X part in the T-die. After merging the molten resins, they are extruded. In FIG. 4, the molten resins are merged at the X section immediately after being extruded.

FIG. 5 is a schematic cross-sectional view showing one example of a laminate according to the present invention. According to FIG. 5, the laminate according to the present invention has a base material 22
It is mainly composed of a polyolefin layer 17, an adhesive resin layer 18, and a polyester resin layer 19. The base material 22 mainly consists of a paper base 12, a metal foil 14 provided via, for example, an ionomer layer 13, and a two-wheel stretched polyester resin layer 15 provided on the metal foil 14. An adhesive or primer coat layer 16 is provided on the polyester resin layer 15, and a polyethylene layer 20, for example, is provided as necessary on the paper substrate 12 on the opposite side. The desired printing 21 can be applied to the image. The ionomer layer 13 is provided for bonding the paper and the metal foil, and instead of the ionomer, polyethylene, ethylene-methacrylic acid copolymer, or the like may be used.

The polyester resin layer 19 is provided so as to suppress the permeability of beverages, etc., to be hygienic, and not to adsorb or permeate fragrance components. The polyester resin constituting the polyester resin layer includes:
Considering manufacturing into a container, a heat-sealable polyester resin having excellent heat-sealability is preferably used.

The heat-sealable polyester resin has a solubility index of 9.5 or more and a glass transition temperature Tg of 50 to 150, for example.
C. low crystallinity or amorphous polyester resins. If a polyester resin with a glass transition temperature To of 50°C or lower is used, blocking may occur due to the softening and stickiness of the resin during packaging processing or storage, resulting in work problems. If a polyester resin is used, it becomes difficult to make bags and boxes during heat sealing, and if a polyester resin with high crystallinity is used, the heat sealability decreases and the product becomes brittle.

Polyester resin consists of a copolymer of polybasic acid and polyhydric alcohol. As such a polybasic acid, one containing terephthalic acid as a main component is preferable, and as a polyhydric alcohol, one containing ethylene glycol as a main component is preferable.

The above polybasic acids and polyhydric alcohols can each contain other polybasic acids and other polyhydric alcohols as comonomer components.

In the present invention, the heat-sealable polyester specifically includes (1) a co-condensation polymer of two or more dibasic acids mainly containing terephthalic acid and a dihydric alcohol, (2) a co-condensation polymer of two or more dibasic acids mainly containing terephthalic acid and a dihydric alcohol; Examples include cocondensation polymers with at least one type of dihydric alcohol, (3) polyethylene terephthalate, or polymer alloys of the cocondensation polymers of (1) or (2) above and modified polyolefins.

Other dibasic acids that can be included as comonomer components with terephthalic acid include isophthalic acid, naphthalene dicarboxylic acid, diphenyl dicarboxylic acid, diphenoxyethane dicarboxylic acid, diphenyl ether dicarboxylic acid,
Aromatic dicarboxylic acids such as diphenylsulfonedicarboxylic acid; Alicyclic dicarboxylic acids such as hexahydroterephthalic acid and hexahydroterephthalic acid; Aliphatic dicarboxylic acids such as adivic acid, sebacic acid, and azelaic acid; pβ-hydroxyethoxybenzoic acid acid, p-oxybenzoic acid, ε-
Examples include oxyacids such as oxycaproic acid.

In addition, examples of the dihydric alcohol include ethylene glycol, propylene glycol, 1,4-butanediol, 1,4-dicyclohexanedimetatool, trimethylene glycol, tetramethylene glycol, hexamethylene glycol, decamethylene glycol, and neobenchi. Lengellicol, diethylene glycol, 1,1-cyclohexane dimethylol, 1,4-cyclohexane dimethylol, 2,2-bis<4-β-hydroxyethoxyphenyl)propane, bis-(4-β-hydroxyethoxyphenyl)sulfonecyclohexane Diol, 1.
4-bis(β-hydroxyethoxy)benzene, 1,3
-Glycols such as (β-hydroxyethoxy)benzene and the like can be mentioned.

Modified polyolefins preferably used in the present invention include copolymers of ethylene and unsaturated carboxylic acids or esters thereof, and ionomers. Examples of the unsaturated carboxylic acid or polyester thereof include acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, ethyl acrylate, and ethyl methacrylate. The copolymer of ethylene and unsaturated carboxylic acid or its ester preferably has an unsaturated carboxylic acid content of 3 to 20% by weight,
In the case of ester, it is preferable that the content of the ester component is 1 to 20% by weight.

In the present invention, the polyester resin may contain a nucleating agent or various additives such as a lubricant, an antiblocking agent, a stabilizer, an antifogging agent, a coloring agent, and the like. As such a nucleating agent, fine particles of polyolefins or inorganic substances having a particle size of 2 to 10 μm are used. For example, low as a polyolefin! Examples include 5 degree polyethylene, high density polyethylene, linear low density polyethylene, polypropylene, etc., and examples of inorganic substances include carbon black, talc, gypsum, silica, alumina, calcium carbonate, titanium dioxide, graphite, powdered glass, powdered metal, etc. Can be mentioned.

Although the thickness of the polyester resin layer is arbitrary, it is used, for example, in the range of 3 to 100 μm.

The polyolefin layer supports the polyester resin layer together with 1 ml of the adhesive material, suppresses meandering and neck-in during coextrusion, and further improves adhesion to the base material. Examples of the polyolefin contained in the polyolefin layer include polyethylene and polypropylene. In the present invention, the thickness of the polyolefin layer is arbitrary, and is used, for example, in the range of 3 to 100 .mu.m.

The thickness of the adhesive resin layer provided to improve the adhesiveness between the polyester resin layer and the polyolefin layer is arbitrary, and is used, for example, in the range of 3 to 50 μm. However, in order to work as a support for the polyester resin layer, the total thickness of the polyolefin layer and adhesive resin layer must be 10
It is preferably in the range of ~150μ.

Examples of the adhesive resin contained in the adhesive resin layer include an ethylene-α olefin copolymer having a density of 0.910 or less, an unsaturated carboxylic acid-modified polyolefin, and the like. Examples of the polyolefin include polyethylene, polypropylene, polybutene, ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer, ethylene-α-olefin copolymer, and the like.

Here, unsaturated carboxylic acid modification means copolymerization or graft polymerization with carboxylic acid groups, acid anhydride groups, and derivatives thereof. Examples include methacrylic acid, maleic acid, fumaric acid, methacrylic anhydride, maleic anhydride, ethyl methacrylate, glycidyl acrylate, diglycidyl methacrylate, and the like.

Any material such as paper, nonwoven fabric, aluminum foil, or plastic film can be used as the base material, but in order to prevent the contents from permeating due to cracks in the metal foil, a stretched plastic layer may be provided on the side in contact with the polyolefin layer. It is preferable to provide one. The stretched plastic contained in the stretched plastic material is a two-wheel stretched polyester resin or a nylon resin, which is stretched 4 to 6 times in the longitudinal direction and 4 to 6 times in the horizontal direction after molding, and then heat-set after stretching the two wheels. Two-wheel stretched nylon resin is preferably used. Further, the thickness of the stretched plastic layer is preferably 9 to 25 μm.
It is a garden.

The polyester resin forming the two-wheel stretched polyester resin consists of a copolymer of polybasic acid and polyhydric alcohol. As such a polybasic acid, one containing terephthalic acid as a main component is preferable, and as a polyhydric alcohol, one containing ethylene glycol as a main component is preferable. The above polybasic acids and polyhydric alcohols can each contain other polybasic acids and other polyhydric alcohols as comonomer components.

Other polybasic acids that can be included as comonomer components in the polybasic acid include aromatic dicarboxylic acids such as isophthalic acid, naphthalene dicarboxylic acid, diphenyl dicarboxylic acid, diphenoxyethane dicarboxylic acid, diphenyl ether dicarboxylic acid, and diphenylsulfone dicarboxylic acid; Alicyclic dicarboxylic acids such as hexahydroterephthalic acid and hexahydroisophthal It; aliphatic dicarboxylic acids such as adipic acid, sebacic acid, azelaic acid; p-β-hydroxybenzoic acid, p-oxybenzoic acid, ε Oxyacids such as oxycaproic acid, nitrimellitic acid, trimesic acid, 3
．． Aromatic polybasic acids such as 3', 5,5'-tetracarboxydiphenyl; butanetetracarboxylic S! Aliphatic polynucleotides such as! ! : Examples include oxypolycarboxylic acids such as tartaric acid and malic acid.

Further, other polyhydric alcohols that can be included as comonomer components in the polyhydric alcohol include trimethylene glycol, tetramethylene glycol, hexamethylene glycol, decamethylene glycol, neobenzene gelylcol, diethylene glycol, and 1,1-cyclohexane glycol. Methylol, 1,4-cyclohexane dimethylol, 2,2-bis(4-β-hydroxyethoxyphenyl)propane, bis-(4-β-hydroxyethoxyphenyl)sulfonecyclohexane, 1°4-bis(β
-hydroxyethoxy)benzene, 1,3-bis(β-
Examples include glycols such as hydroxyethoxy)benzene; polyhydric alcohols such as phloroglycine, 1.2°4.5-tetrahydroxybenzene, glycerin, trimethylolethane, trimethylolpropane, and pentaerythritol.

In the present invention, the polyester resin may contain the same nucleating agent or various additives as used in the polyester resin layer, such as a lubricant, an anti-blocking agent, a stabilizer, an antifogging agent, a coloring agent, etc. .

The base material according to the present invention preferably has an adhesive or primer coat layer on the side in contact with the polyolefin layer. When the surface of the base material on the side in contact with the polyolefin layer has a layer made of plastic or the like, it is necessary to apply an adhesive or a primer coating agent using a roll coating method or a gravure coating method.

Examples of adhesives include one-component or two-component reactive urethane adhesives, polyester adhesives, acrylic-urethane adhesives, epoxy-urethane adhesives, etc. Primer coating agents include, for example, polyethylene imine. , alkyl titanates, and the like. In this case, the adhesive is preferably applied in a range of 0.5 g/f to 10 (J/f), and the primer coat agent is applied in a range of 0.01 (It
It is preferable to apply the coating in a range of /f to 0.50/w2.

Further, the base material constituting the laminate according to the present invention is not particularly limited as long as it can be used as a structural support for a container, but it is preferable that the base material contains paper in its layer structure. The paper constituting the above base material is 1,100 to 4 tsubo
00111/f white paperboard, base paper for bulk cartons, acid-resistant paper, etc. are preferably used.

A metal foil is usually provided on the paper to prevent penetration of beverages, etc., and a metal foil made of aluminum with a thickness of 6 to 20 μm is preferably used. Such metal foil is provided on the paper using, for example, polyethylene, ethylene-methacrylic acid copolymer, ionomer resin, or the like. Further, a layer made of polyethylene or the like may be provided on the paper opposite to the metal foil.

The laminated material of the present invention can have various layer configurations within the scope of the present invention, for example, printing ink/polyethylene/
Layer configurations include w1/ionomer/aluminum foil/biaxially oriented polyester resin/adhesive or primer coating agent/polyolefin/adhesive resin/polyester resin.

The laminate according to the present invention is manufactured, for example, by the following method. That is, (1) extrusion coating polyethylene on paper and printing on the polyethylene. On the other hand (2)
Dry laminate biaxially oriented polyester resin onto aluminum foil. (3) Adhere the paper surface of (11) and the aluminum foil surface of (2) via polyethylene, ionomer resin, ethylene-methacrylic acid copolymer, etc. (
4) (Create a base material by applying an adhesive or a primer coating agent on the two-wheel stretched polyester resin surface of No. 21 using a roll coating method or a gravure coating method. The base material is the molten film obtained by the above method. In one continuous process (so-called in-line), the polyolefin membrane is immediately pressed onto the ozone-treated polyolefin membrane surface and cooled.

Containers to which the laminate according to the present invention can be preferably applied include various forms of containers containing highly permeable liquid beverages, such as alcohol, whiskey, juice, coffee, barley tea, oolong tea, mineral water, soups, etc. For example, containers such as a tetra pack type and a block type, the appearance of which are shown in FIGS. 6 and 7, can be mentioned. In order to produce, for example, the container shown in FIG. 6 above using the laminate according to the present invention, the first step is to form a sleeve as shown in FIG. 8. In this process, one side edge is folded back to form a sleeve so that the end surface of the container constituent material is not exposed to the inner surface of the container and comes into contact with the beverage content. The side edges of the polyester are framed and sealed, then the bottom is formed in the second step, the contents are filled in the third step, and finally the top is formed in the fourth step to create a container. can do.

Another method is to form a container by heat-sealing the polyester surfaces together when filling the roll-shaped laminated material of the present invention with contents.

Furthermore, the laminate according to the present invention has a property of not easily adsorbing medicinal ingredients such as menthol and camphor, so it can effectively retain medicinal ingredients, and can also be applied as a packaging material for poultices. Furthermore, it can also be applied to fragrance mixtures, bath coloring agents, coloring agents for preventing permeation and volatilization of fragrances, and the like.

[Example] EXAMPLES The present invention will be explained in more detail with reference to Examples below.

Example 1 A polybasic acid consisting of 60 mol% of terephthalic acid and 140 mol% of isophthalic acid and ethylene glycol were co-condensed to obtain a co-condensed polyester resin (glass transition temperature To=58°C, solubility index 103). The obtained cocondensation polymerized polyester resin, ethylene-maleic anhydride copolymer and low density polyethylene (density 0.924>
were supplied to an extruder and coextruded at a temperature of 280°C, and then ozone with an ozone concentration of 10 g/m' was added at a rate of 1.5 Nn'/hr onto the low-density polyethylene surface of the molten three-layer film moving at a speed of 60 m/win. It was sprayed at the same ratio (Figure 1).

On the other hand, polyethyleneimine was applied to the two-wheel stretched polyester resin surface of a sheet made of a 12-μm-thick two-wheel stretched polyester resin and a 7-μ-thick aluminum foil using a roll coating method at a coating amount of 0.1 g/f. A base material was obtained. The polyethyleneimine-coated surface of the base material and the ozone-treated molten low-density polyethylene surface are immediately pressed together in a so-called in-line manner and cooled to obtain a laminate according to the present invention (FIG. 1). The thickness of each layer of the obtained laminate was 15 μm for the cocondensation polymerized polyester resin layer, 15 μm for the low density polyethylene layer, and 10 μm for the ethylene-maleic anhydride copolymer layer. In addition, regarding the obtained laminate, meandering or neck-in on one side of the film,
Adhesive strength and heat seal strength were measured.

Measurement of adhesive strength: The #R laminate was cut into strips with a width of 15 mm, and the distance between the base material and the low-density polyethylene layer was 30 mm.
It was peeled off at a tensile speed of 0.01 m/cm/10, and its strength was measured.

Measurement of heat seal strength: The obtained laminate was
Cut the two strips into strips, align the cocondensation polymerized polyester resin layer surfaces, and seal bar temperature 180°C, sealing time 1 second, sealing pressure 2.81 kmM.
After heat sealing with Cf, 300mm+/sin
The film was peeled off at a tensile speed of 1, and its strength was measured.

The results are shown in Table 1.

Comparative Example 1 The base material obtained in Example 1 was coated with the cocondensation polymerized polyester resin obtained in Example 1 by single-layer extrusion coating at a temperature of 280° C. without ozone treatment to obtain a laminate.

The thickness of the cocondensation polymerized polyester resin layer of the obtained laminate was 40 μ-.

The same measurements as in Example 1 were performed on the obtained laminate. The results are shown in Table 1.

Comparative Example 2.3 The cocondensation polymerized polyester resin obtained in Example 1, low density polyethylene, and ethylene-maleic anhydride copolymer were added to the base material obtained in Example 1 at a temperature of 280°C without ozone treatment. Alternatively, comparative laminates were obtained by coextrusion coating at 320°C. The thickness of each layer of the obtained laminate was the same as in Example 1.

The same measurements as in Example 1 were performed on the obtained laminate.

The results are shown in Table 1.

However, in Comparative Example 3, the viscosity of the cocondensation polymerized polyester resin became low, the thickness of each layer became non-uniform, and gel-like insoluble matter flowed out from both sides of the T-die 3 hours after the start of extrusion, resulting in a stable product. As is clear from the production table 1,
The laminate of Example 1 according to the present invention had small meandering and neck-in, and had satisfactory adhesive strength and heat seal strength.

[Effects of the Invention] As explained in detail above, in the present invention, a polyolefin is used instead of the conventionally used expensive adhesive polyolefin, and the number of steps is reduced, so a laminate can be obtained at a low cost. Ta. That is, according to the present invention, it was possible to provide a method for manufacturing a laminate that has small meandering/neck-in, excellent workability, sufficient adhesive strength, and low cost.

[Brief explanation of drawings]

FIG. 1 is a schematic process cross-sectional view showing an example of the manufacturing method of the present invention, and FIGS. 2 to 4 are schematic partial process cross-sectional views showing an example of the coextrusion method used in the present invention, FIG. 5 is a schematic cross-sectional view showing one example of the laminate according to the present invention, and FIG.
7 and 7 are perspective views showing an example of a container made using the laminate according to the present invention, and FIG. 8 is a perspective view showing an example of a container made using the laminate according to the present invention, and FIG. 8 is a sleeve making step in making the container shown in FIGS. FIG. 1... Ozone generator 2... Ozone gas 3.
...T-die 4...T-die exit 5...
Crimping part 6...Base material 7...Cooling roll 8...Roll 9...Laminated body
10... Extruder 11... Feed block 12.
...Paper base 13...Ionomer layer 14...Metal foil 15...Two-wheel stretched polyester resin layer 16...
Adhesive or primer coat layer 17...Polyolefin layer 18...Adhesive resin layer 19...Polyester resin layer 20...Polyethylene layer 21...Printing 22...
・Base material 23...Sleeve part 24...
Bottom part 25...Top part 26...Polyester resin layer 27...Polyethylene layer Fig. 1 Fig. 3 Fig. 4 Fig. 7 Fig. 8 G

Claims (2)

[Claims] (1) Coextrude polyester resin, adhesive resin, and polyolefin at a temperature of 300°C or less, blow ozone gas onto the surface of the molten polyolefin layer, and then press-bond the surface of the polyolefin layer and the base material to form a laminate. A method for manufacturing a laminate, characterized by: (2) The method for manufacturing a laminate according to claim 1, wherein the base material has an adhesive or a primer coat layer.