JPS5954033B2 - Method for manufacturing laminates - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a coextrusion laminate, and more specifically, polyethylene A and a copolymer of ethylene and α,β-unsaturated carboxylic acid or its metal neutralized product B are heated through two slits. After extruding as two molten webs from a flat die with The present invention relates to a method for producing a laminate with strong adhesive strength between layer A, layer B, and other layers by melt-press bonding.

Today, laminates obtained by extrusion laminating polyethylene onto various base materials are widely used as packaging materials in large quantities.

However, in recent years, as packaging speeds have increased and the items to be packaged have become more diverse, polyethylene laminates are sometimes lacking in sealing performance and various types of strength. Copolymers of ethylene and vinyl acetate, copolymers of ethylene and α,β monounsaturated carboxylic acids, or metal neutralized products thereof are increasingly being used. In particular, ethylene-α,β-monounsaturated carboxylic acid copolymers and their metal neutralized products have excellent low-temperature heat-sealability and hot-sealability that enable faster packaging speeds in various types of automatic filling and packaging systems. , its performance as a packaging material is attracting attention due to its ability to seal against contaminants.

Furthermore, this resin has excellent adhesion to various metals including aluminum, and has the characteristic that strong adhesive strength can be obtained by extrusion lamination without applying an anchor coating treatment to the metal surface. As described above, it can be said that the ethylene-α,β-monounsaturated carboxylic acid copolymer and its metal neutralized product are excellent resins for packaging materials, but on the other hand, they have the drawback of being expensive.

Therefore, we have developed a coextrusion laminate in which the recently economically advantageous ethylene-α,β-monounsaturated carboxylic acid copolymer or its metal neutralized product is used in the minimum necessary layer thickness, and the remaining layer thickness is replaced by polyethylene. The fact that this product has been developed has great economic benefits, and this coextruded laminate is a suitable packaging material with a good balance between performance and price, and has already been put into commercial use in some areas. has been made into However, in the commonly practiced coextrusion molding, that is, the in-die adhesion method in which two molten resins are joined inside the die and laminated, polyethylene A and ethylene-α,β-unsaturated carboxylic acid are co-extruded. In the case of a laminate in which the polymer or its metal neutralized product B is coextruded and laminated as a base material, the ethylene layer and the ethylene-α,β-unsaturated carboxylic acid copolymer or its metal neutralized resin are Since the polarities of the two layers are greatly different, the wetting and compatibility chemical affinity is poor, and therefore the interlayer adhesion strength between both layers A and B is not strong enough.As a result, the heat sealing strength and hot There was also a drawback that the sealing performance was not sufficient.

The present inventors conducted extensive research to resolve the drawbacks regarding interlayer adhesion strength in coextrusion laminates having the above structure, and found that one layer of polyethylene A and ethylene-α,β-unsaturated carboxylic acid copolymer or To make a coextrusion laminate with 5 configurations in which layer A or layer B of the coextrusion molten web is in contact with the base material and metal neutralized product B is the other layer, resins A and B are cut through two slits. The surface of the molten web of A on the side to be bonded to B is air oxidized to a certain optimum range. By pressing and cooling at the same time, the A and B layers in the conventional in-die adhesive coextrusion laminate can be bonded together.
It has been found that it is possible to produce a coextruded laminate with a much higher adhesive strength than the above (layer adhesion strength). That is, the present invention has a single layer of polyethylene A,
A coextruded molten web containing a copolymer of ethylene and α,β-monounsaturated carboxylic acid or its metal neutralized product B as another layer is placed on a base material so that either layer A or layer B is in contact with the base material. To produce a Δ laminate by extrusion lamination, resins A and B are simultaneously melt-extruded through each slit of a flat die having two slits, and the degree of surface oxidation at the interface of layer A in contact with layer B is adjusted to a carbonyl group. After oxidizing to a concentration of 0.8 to 4.0 [carbons/10,000 carbon], a metal roll and a rubber roll are combined to form A layer/B layer/base material or B layer/A layer/base material. A to the base material between
The present invention relates to a method for producing a coextrusion laminate having strong interlayer adhesion between layers A and B and excellent adhesion between other layers, characterized by melt-pressing and cooling layers A and B at the same time. In the present invention, the polyethylene layer (
The degree of surface oxidation at the interface of layer A) has a very important meaning.

That is, in the present invention, the surface oxidation degree of layer A in contact with layer B is 0.8 to 4.0 [numbers/10000] in terms of surface carbonyl group concentration.
Only in the case of carbon], the adhesion with layer B is strong enough for practical use, and the sealing strength as a laminate and other physical properties as a packaging material are also good. Note that the carbonyl group concentration of 0.8 to 4.0 [numbers/10,000 carbons] means that carbonyl groups are present on the resin layer surface at a ratio of 0.8 to 4 carbonyl groups per 10,000 carbons. It is. Surface oxidation degree is 0.8/1 carbonyl group concentration
Even if the same equipment is used, A and B are less than 0,000 carbon.
If the adhesion between the two layers is insufficient and the degree of surface oxidation is more than 40 carbonyl groups/10,000 carbons, the oxidative deterioration will be too large and the heat sealing strength of the laminate will decrease. Both have a strong odor and are unsuitable as packaging materials. In order to set the surface oxidation degree of layer A to a carbonyl group concentration of 0.8 to 4.0 [numbers/10,000 carbons], resins A and B are not laminated inside the die, but are made from a flat die with two slits. A and B are each extruded, and the resin temperature of resin A at the die exit at that time is 290 to 330 ° C., and the resin temperature of resin B at the die exit is arbitrary, but preferably 250 to 330 ° C.
The temperature is 0°C, and the air gap (distance between the die exit and the crimping part) and the web take-up speed are determined so that the contact time of the molten webs A and B with the air is 0.05 to 0.2 seconds. Polyethylene A used in the present invention has no limitations other than that it can be extruded and laminated, but M. I. is preferably in the range of 2 to 20.

In addition, in the ethylene-α,β-unsaturated carboxylic acid copolymer and its metal neutralized product B used in the present invention, the α,β-unsaturated carboxylic acid comonomer copolymerized with ethylene includes acrylic acid, meth Acrylic acid, ethacrylic acid,
Examples include itaconic acid, maleic acid, and fumaric acid.

The concentration of these comonomers in the copolymer ranges from 1 to 25
Mol% is preferred. In addition, the metal ions used in the metal neutralized product of the ethylene-α,β-unsaturated carbonic acid copolymer in the present invention include Na+, K+ as monovalent metal ions.
, Li+, Cs+, Ag+, Hg+, Cu+, and 2
Be++ Mg++ Ca++ B as valent metal ions
a++Cu++ (冫j++, Hg++,
Sn++, Pb++, Fe++, CO+1,
There are Ni++ and Zn++, and the trivalent metal ion is A.
Examples include l+++, SO+++, Fe+++, and Yt+++.

Although there is no particular restriction on the degree of neutralization, it is preferable that the MI after neutralization with metal ions is in the range of 2 to 20. Furthermore, there are no particular limitations on the base material used in the present invention,
All of the substrates commonly used in extrusion coating molding can be used.

Examples of such base materials include paper such as paperboard, kraft paper, and thin paper; metal foils such as aluminum foil, copper foil, and tin foil; and various plastics such as cellophane, polypropylene, nylon, polyester, and polystyrene. Examples include unstretched or unstretched films, films coated with vinylidene chloride or the like, and laminated products thereof. 2. When laminating the coextruded web, these base materials may or may not be pretreated, but pretreatments used in normal extrusion lamination, such as anchor coating and , corona discharge treatment, flame treatment, etc. are preferably applied as necessary. Hereinafter, a known coextrusion lamination method and the present invention will be explained with reference to the drawings.

FIG. 1 is a diagram showing the principle of conventionally known in-die bonding type coextrusion laminate molding.

The coextrusion die 1 has two resin inlets 2 and 3, and the molten resin x entering from 2 spreads in the die width direction in the manifold 4. Further, the molten resin Y flowing into the die from 3 spreads in the die width direction in the manifold 5. The resins X and Y, which have respectively spread in the width direction of the die, are then merged and laminated at the merge section 6, and extruded from the die lip 7 as a coextruded web. This coextruded web is pressed onto the base material Z between the nip roll 8 and the cooling roll 9, and at the same time is cooled and solidified. In this molding method, the adhesive interface of the coextruded web, that is, the X1 plane of resin Since it does not come into contact with air, it does not undergo oxidation.

Now, if X is polyethylene and Y is an ethylene-α,β-unsaturated carboxylic acid copolymer or its metal neutralized product, the adhesive interface of the polyethylene layer of the coextruded web will remain unchanged even if the resin temperature and air gap passage time are changed. Since X1 cannot be exposed to air, it cannot undergo oxidation and remains almost polar. Therefore, the resin itself does not have sufficient wettability, compatibility, or chemical bonding strength with the adhesive interface Y1 of the Y layer, which has polarity, and as a result, the interlayer adhesive force between x and Y cannot be said to be sufficiently strong. . Next, the present invention will be explained with reference to FIG.

FIG. 2 is a diagram showing the principle of the molding method used in the present invention.

This flat die has two completely separate flow paths from inlet to outlet within the die, and the two resin layers are laminated outside the die. The resins x and Y melted and kneaded by two separate extruders flow into the die 10 through inlets 1 and 12 of the die 10, respectively.

The resins X and Y, which have spread in the die width direction in the manifolds 13 and 14, are then extruded through die outlets 15 and 16 as separate molten webs. Both sides of the molten webs X and Y are exposed to air in an air gap. In the present invention, when bringing both sides of the molten webs X and Y into contact with air in an air gap, the resin temperature under the die of the resin x is set to 290 to 330°C,
In addition, by setting the air gap and web take-up speed so that the contact time with air is 0.05 to 0.2 seconds,
The surface oxidation degree of the adhesive surface X2 with resin X (7) Y is 0.8 to 4.0 [pieces/10000]
After that, the laminate is oxidized until it reaches a range of carbon], and is then compressed to the base material Z between the two rolls 8 and the cooling roll 9 and cooled at the same time to obtain a laminate.

In the present invention, x in FIG. 2 is an ethylene-α,β-unsaturated carboxylic acid copolymer or a metal neutralized product thereof,
Y can also be polyethylene. Figures 3, 4 and 5 each show examples of laminated products obtained according to the present invention.

Figure 3 shows a cellophane/polyethylene/aluminum foil laminate made by sandwich-laminating an anchor-coated cellophane base material and aluminum foil with polyethylene.Anchor-coat treatment was applied to the aluminum foil surface of the cellophane/polyethylene/aluminum foil laminate. Then, according to the present invention, a coextruded web of polyethylene and an α,β monounsaturated carboxylic acid copolymer or its metal neutralized product is laminated.

The manufactured laminate has sufficiently strong adhesive strength between each layer, and since the sealing layer is made of α, β monounsaturated carboxylic acid copolymer or its metal neutralized product, it has good low temperature sealability and hot sealability. It has excellent sealing strength and is highly suitable as a packaging material. In particular, this laminate is suitable for packaging dry confectionery such as potato chips, taratuka and bisguette, powdered foods such as powdered juice, powdered shabbiness, powdered soup and powdered mixes, coffee and tea. Note that the cellophane base material in this laminate structure can be changed to paper, oriented polypropylene, oriented polyester, oriented nylon, or a film coated with vinylidene chloride, etc., depending on the strength, rigidity, type of packaging machine, etc., as necessary. can. Further, the cellophane and aluminum foil may be laminated by dry lamination using an adhesive instead of sandwich lamination using polyethylene. Figure 4 shows a substrate in which stretched polyester and aluminum foil are dry-laminated using an adhesive, and α,β-unsaturated carboxylic acid copolymer or its metal neutralized product and polyethylene are applied to the aluminum foil surface according to the present invention. This is a laminate of coextruded webs.

The produced laminate has sufficient adhesion strength between the layers of the coextruded web, and the α,β monounsaturated carboxylic acid copolymer or its metal neutralized product firmly adheres to the aluminum foil. Furthermore, since the adhesive strength of these products is less reduced by the filler, it is suitable for packaging products such as jump products, conditioners, and cosmetics containing alcohol. Note that the stretched polyester in the construction of this laminate can be replaced with paper, cellophane, stretched polypropylene, stretched nylon, or a film obtained by coating these with vinylidene chloride, if necessary. FIG. 5 shows a polyethylene/paperboard/polyethylene/aluminum foil composite substrate produced by extrusion coating of polyethylene. It is made by laminating a co-extruded web of polyethylene and polyethylene.

In the manufactured laminate, the interlayer adhesion strength of the coextruded web is sufficiently strong, and the α,β-unsaturated carboxylic acid copolymer or its metal neutralized product firmly adheres to the aluminum foil. In addition, because the decrease in adhesive strength due to fillers is small, juice, soy sauce, salad oil,
Suitable for liquid containers such as dressings. The laminate consisting of ethylene-α,β-unsaturated carboxylic acid copolymer or its metal neutralized product B/polyethylene A/base material or A/B/base material obtained by the method of the present invention has The adhesive strength, especially the adhesive strength between layer A and layer B, is strong, and it has excellent low-temperature heat-sealing properties, heat-sealing strength, hot-sealing properties, sealing properties against contaminants, etc., and as a result, it becomes an excellent packaging material.

The present invention will be explained in more detail below with reference to Examples.

In Examples and Comparative Examples, the degree of surface oxidation (carbonyl group concentration) of the interface of the polyethylene layer (layer A) in contact with layer B and the physical properties of the obtained laminate were measured by the following methods.

(1) Carbonyl group concentration at the A layer interface A reflection infrared spectrophotometer was used.

First, set the measurement sample on a reflecting prism and set the wave number to 1800.
Scan from cm-1 to 1250 cm-1. wave number 17
Absorbance A1 and 1 of carbonyl group at 20 cm
Determine the absorbance A2 of the ethylene group at 370 cm-1, then calculate A1/A2, and calculate the A1/A2 prepared in advance.
The carbonyl group concentration of the sample is determined from the calibration curve of A2 versus carbonyl group concentration. (2) Cut the laminate of the adhesive strength sample into a sample width of 15 mm, and peel it at a peel rate of 3 at a temperature of 23°C and a humidity of 60% RH.
00 mm/Mm and a peel angle of 90 degrees, and the peel strength at that time was measured using an autograph.

(3) Heat-sealing strength Two laminates were heat-sealed using a heat sealer under conditions of a sealing pressure of 2 kg/CIIl2 and a sealing time of 0.5 seconds.

Next, this heat-sealed sample was cut to a sample width of 15 mm, and this was peeled at a peeling rate of 300 mm/min and a peeling angle of 90° under conditions of a temperature of 23 ° C. and a humidity of 60% RH.
The peel strength at that time was measured using an autograph.
(4) Hot sealability Seal obtained when two laminates are heat-sealed and a load of 45 g is applied to each laminate immediately after the seal bar is separated, so that a peeling force is applied at a peel strength of 225°. It is expressed in peel distance [Mm].

A smaller value indicates better hot sealing performance. Example 1 Melt index 65, density 0.917g/CIrl
The low-density polyethylene of No. 3 was melt-kneaded as resin X in a first extruder, and fed into the base material side manifold 13 in FIG. 2 at a resin temperature of 320°C.

When the temperature of the substrate-side die body 10 was set to 330°C, the temperature of the molten resin web extruded from the die directly below the die was 315°C. On the other hand, an ethylene-methacrylic acid copolymer having a melt index of 10 and a methacrylic acid content of 10% by weight was melt-kneaded as resin Y in a second extruder, and the resin was heated to 310°C by cooling rolls in the die. It was sent into the side manifold 14. When the temperature of the die body on the cooling roll side was set at 320°C, the temperature of the molten web directly under the die was 305°C. The air gap was set to 160 mm, the take-up speed was 100 m/min, and the air gap passage time was 0.096 seconds! After applying an organic titanate-based anchor agent to the aluminum foil surface of a composite base material made of paper/polyethylene/aluminum foil that had been prepared in advance under the following conditions, A polyethylene layer and an ethylene-methacrylic acid copolymer layer were coextruded coated. At this time, the degree of oxidation of the polyethylene interface in contact with the ethylene-methacrylic acid copolymer layer can be determined by stopping the second extruder and
Only polyethylene was extruded and coated onto the base material using an extruder under the processing conditions described above. Thereafter, the concentration of carbonyl groups on the surface was measured by reflection infrared spectroscopy. As a result, the degree of oxidation at the interface of polyethylene is 1.
It was 7 [pieces/10,000 carbons]. The thickness of the coated polyethylene layer was 10μ, the thickness of the ethylene-methacrylic acid copolymer layer was 10μ, and the total thickness of the coated resin was 2μ.
It was 0μ. Table 1 shows the measurement results for the adhesive strength, heat seal strength, and hot sealability of this laminate.

As shown in Table 1, the adhesive strength between aluminum foil and polyethylene of the laminate obtained and the interlayer adhesive strength between polyethylene and ethylene-methacrylic acid copolymer are both strong enough for practical use. It can be seen that the laminate has good low-temperature sealing properties, heat-sealing strength, and hot-sealing properties. Example 2 Melt index 65, density 0.917 g/Clll
The low-density polyethylene of No. 3 was melt-kneaded as resin X in a first extruder, and fed into the substrate-side manifold 13 according to the present invention at a resin temperature of 330°C.

When the temperature of the die body on the base material side was set to 340°C, the temperature of the molten resin web extruded from the die directly under the die was 322°C. On the other hand, melt index 50
, a metal neutralized product obtained by oxidizing an ethylene-methacrylic acid copolymer with a methacrylic acid content of 15% by weight with Zn++ ions to a melt index of 10 was used as the second resin Y.
The mixture was melt-kneaded in an extruder and fed into the cooling roll side manifold in the die at a resin temperature of 285°C. When the die body on the cooling roll side was set at 290°C, the temperature of the molten web directly under the die was 285°C. Coextrusion coating was carried out under the same conditions as in Example 1, including air gap, take-up speed, substrate used, and anchor coating treatment. In addition, when the surface oxidation degree of the polyethylene interface in contact with the ethylene-methacrylic acid copolymer layer was measured by the same method as in Example 1, the carbonyl group concentration was 21 [numbers/10,000 carbons]. It was hot.

The thickness of the coated polyethylene layer and the Zn ion neutralized layer of ethylene-methacrylic acid copolymer are both 1.
The total thickness of the coated resin was 20μ.
Table 1 shows the measurement results of the adhesive strength, heat seal strength, and hot sealability of this laminate.

As can be seen from Table 1, the adhesion strength between aluminum foil and polyethylene of the laminate obtained and the interlayer adhesion strength between polyethylene and ethylene-methacrylic acid copolymer Zn++ and ion neutralized product are both sufficient for practical use. is strong and
It is also seen that this laminate has good low-temperature sealing properties, heat-sealing strength, and hot-sealing properties. Example 3 An ethylene-methacrylic acid copolymer with a melt index of 10 and a methacrylic acid content of 10% by weight was occluded with Zn++ ions to have a melt index of 5. The metal neutralized product was used as the first resin x. Melt and knead with an extruder, resin temperature 3
It was fed into the substrate side manifold 13 of the coextrusion die according to the invention at 20°C.

When the temperature of the die body on the substrate side was set at 330°C, the temperature of the molten web extruded from the die was 315°C. On the other hand, melt index 5, density 0.919g
/CII]S polyethylene was melt-kneaded as resin Y in a second extruder, and fed into the cooling roll side manifold 14 in the die at a resin temperature of 310°C. When the die body on the cooling roll side was set at 320°C, the temperature of the molten web directly under the die was 307°C. The metal of ethylene-methacrylic acid copolymer was applied to the aluminum foil surface of the composite base material consisting of cellophane/polyethylene/aluminum foil under the conditions that the air gap was 180 mm, the take-up speed was 150 m/min, and the air gap passage time was 0.072 seconds. Coextrusion coding was carried out so that the Japanese products were in contact with each other. In addition, the degree of oxidation of the polyethylene interface in contact with the Zn++ ion neutralized layer of the ethylene-methacrylic acid copolymer of the present laminate can be determined by stopping the first extruder and extruding only polyethylene from the second extruder. After extrusion coating on a silicone-coated release paper under the same processing conditions as above, the release paper was removed and carbonyl groups on the surface were quantitatively analyzed by reflection infrared spectroscopy.

As a result, the degree of oxidation at the polyethylene interface was found to be 12 carbonyl groups/10,000 carbons. The thickness of the coated ethylene-methacrylic acid copolymer neutralized with Zn++ ions is 10μ, and the thickness of polyethylene is 2μ.
The total thickness of the coated resin was 30μ.
Measurement results of adhesive strength, heat seal strength, and hot sealability of this laminate. are shown in Table 2. Adhesive strength and ethylene-methacrylic acid copolymer neutralized with Zn++ ions between the aluminum foil of the obtained laminate and the ethylene-methacrylic acid copolymer.
The interlayer adhesive strength between the methacrylic acid copolymer neutralized by Zn++ ions and polyethylene was strong enough for practical use.

Comparative Example 1 A two-layer multi-manifold die (Figure 1) with an in-die adhesion method used in normal coextrusion coating was used, and the melt index was 65 and the density was 0.917 g/C.
Polyethylene of nl3 was melt-kneaded as resin x in a first extruder, and fed into the base material side manifold 4 at a resin temperature of 330°C.

On the other hand, an ethylene-methacrylic acid copolymer with a melt index of 50 and a methacrylic acid content of 15% by weight was
The neutralized product, which had been neutralized with ++ ions to have a melt index of 10, was melt-kneaded as resin Y in a second extruder and fed into the cooling roll side manifold 5 at a resin temperature of 285°C. When the temperature of the die body was set at 340°C, the temperature of the coextruded web extruded from the die directly below the die was 340°C.
It was 05°C. Using this coextruded web, coextrusion coating was performed using the same processing conditions as in Example 2, such as air gap take-off speed, base material, anchor coating treatment, and coating thickness. Table 1 shows the measurement results of the adhesive strength, heat seal strength, and hot sealability of the obtained laminate. As can be seen from Table 1, the interlayer adhesion strength between polyethylene and Zn++ ion neutralized product of ethylene-methacrylic acid copolymer in the obtained laminate was lower than that of the sample of Example 2. The sealing strength and hot sealability were also insufficient, making it unsatisfactory as a packaging material. Comparative Example 2 An ethylene-methacrylic acid copolymer with a melt index of 10 and a methacrylic acid content of 10% by weight was occluded with Zn+1 ions to give a melt index of 5.The metal neutralized product was used as the first resin x. Melt and knead with an extruder, resin temperature 3
It was fed at 20° C. into the substrate side manifold 13 of the coextrusion die (FIG. 2) according to the present invention.

When the temperature of the die body on the substrate side was set at 330°C, the temperature of the molten web extruded from the die was 315°C. On the other hand, melt index 5, density 0.919g
/d of polyethylene was melt-kneaded as resin Y in a second extruder, and fed into the cooling roll side manifold in the die at a resin temperature of 290°C.

When the die body on the cooling roll side was set at 290°C, the temperature of the molten web directly under the die was 285°C. Air gap 160mm and take-up speed 220m
Coextrusion coating was performed on the same base material as in Example 3 with the same coating thickness under the processing conditions of 0.044 seconds per minute and air gap passage time of 0.044 seconds. The measurement results of the adhesive strength, heat seal strength, and hot sealability of the obtained laminate were
Shown in the table. Z of the laminate aluminum foil and ethylene-methacrylic acid copolymer obtained as shown in Table 2
Although the adhesive strength of the neutralized product by n++ ions was sufficient for practical use, the interlayer adhesive strength between this neutralized product and polyethylene was insufficient, and the heat seal strength was also low.

Also, Z of the ethylene-methacrylic acid copolymer at this time
The carbonyl group concentration on the polyethylene surface in contact with the n++ ion neutralized layer was measured by reflection infrared spectroscopy in the same manner as in Example 3, and found to be 0.7 [numbers/10,000].
carbon].

Comparative Example 3 In Example 3, the resin temperature on the second extruder side was set to 330°C, the die setting temperature was set to 340°C, the molten web temperature directly under the die was set to 330°C, and the take-up speed was set to 5.
Set to 0m/min and air gap passing time is 0.216
A laminate was produced at the same time as in Example 3, except that the time was changed to 2 seconds.

Adhesive strength, heat seal strength, and
The measurement results of hot sealability are shown in Table 2.

As shown in Table 2, the adhesion between the aluminum foil of the laminate obtained and the Zn+1 ion neutralized product of ethylene-methacrylic acid copolymer and the interlayer adhesion between this neutralized product and polyethylene are practically sufficient. Although it was strong, it had a strong odor due to oxidative decomposition of polyethylene, and its heat seal strength was low, so it was judged to be unsuitable as a packaging material. In addition, when the carbonyl group concentration on the polyethylene surface was measured by reflection infrared spectroscopy in the same manner as in Example 3, it was found that 4
．． It was 2 [pieces/10,000 carbons].

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of a flat die for coextrusion coating that has been commonly used in the past. FIG. 2 is a schematic diagram showing a cross section of a flat die for coextrusion coating used in the present invention. Figures 3, 4, and 5 all show examples of the structure of laminates made using the present invention. 17... Ethylene-α,β-unsaturated carboxylic acid copolymer or its neutralized product, 18... Polyethylene, 19... Anchor coating agent, 20... Aluminum foil, 21... Cellophane, 22...Melting web, 23.
...Base, 24...Adhesive, 25...Stretched polyester film, 26...Paperboard.

Claims (1)

[Claims] 1 A coextruded molten web having one layer of polyethylene A and another layer of a copolymer of ethylene and α,β-unsaturated carboxylic acid or its metal neutralized product B, layer A or layer B. To manufacture a laminate by extrusion laminating on a base material so that one of the layers is in contact with the base material, resins A and B are simultaneously melt-extruded from each slit of a flat die having two slits, and the After oxidizing the surface of the interface in contact with layer B to a carbonyl group concentration of 0.8 to 4.0 [numbers/10,000 carbons], layer A/layer B/base material or layer B/layer A/ The A layer and the B layer are melted and pressed onto the base material between a metal roll and a rubber roll, and cooled at the same time.The interlayer adhesion between the A layer and the B layer is strong. A method for producing a coextrusion laminate that also has excellent interlayer adhesion.