JPH0242068B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a laminated material, and more particularly, to a laminated material that has excellent heat resistance and interlayer adhesion and is easy to manufacture.

Conventionally, laminated materials obtained by laminating a suitable sealing material layer such as an unstretched polypropylene film via an adhesive layer to a base material such as stretched polypropylene film, stretched polyamide film, polyester film, or metal foil have been used for food packaging. It is used in many fields, mainly in In addition to the above-mentioned polypropylene film, high-density polyethylene, low-density polyethylene, and the like are generally used as this sealing material layer.

However, although low-density polyethylene and the like can be heat-sealed at relatively low temperatures, they do not have sufficient heat resistance, strength, etc., and their field of use is greatly limited. For this reason, unstretched polypropylene films are most commonly used in fields where heat resistance, strength, rigidity, etc. are required. Laminated materials using this unstretched polypropylene film are manufactured by an extrusion lamination method or a dry lamination method, of which the extrusion lamination method is often used. however,
In this extrusion lamination method, it is necessary to perform anchor treatment on the surface of the unstretched polypropylene film used as the film for the sealant layer in order to improve the adhesion with the molten resin such as low-density polyethylene used as the adhesive layer. be. However, since a solvent is used in the anchoring process, it is inevitable that the solvent will remain on the laminated film after lamination with the base film, and the transfer of the solvent to the packaged food products may lead to safety problems and the adhesion of odor. There are problems such as. Furthermore, manufacturing costs such as the cost of equipment for anchor treatment, the energy cost for drying, and the cost of anchor treatment agents increase, and the equipment and manufacturing are not always sufficient in terms of pollution and safety.
Improvements were desired.

The inventors of the present invention have conducted extensive research in order to eliminate the drawbacks of sealing layer films made of unstretched polypropylene films, and as a result, they have developed an anchor treatment using a multilayer material having layers made of a resin composition of a specific composition. It has been found that a laminated material with excellent adhesive strength can be obtained without the need for coating. The present invention was made based on these findings, and aims to provide a laminated material that has excellent adhesive strength, is easy to manufacture, and has excellent safety.

That is, the present invention uses (A) a polypropylene resin and an ethylene-α having a density of 0.900 to 0.950 g/cm ³ as a base material.
- A multilayer material consisting of a resin composition layer made of an olefin copolymer and (B) a polypropylene resin layer.
(A) This relates to a laminated material in which a resin composition layer is laminated via an adhesive layer so as to face a base material surface.

The base material of the laminated material of the present invention includes synthetic resin, paper, cellophane, aluminum foil, etc. that can be formed into a film or sheet shape. Examples of synthetic resins include high-density polyethylene, medium-density polyethylene,
Polyolefin polymers such as low density polyethylene, ethylene-α-olefin copolymer, ethylene-unsaturated carboxylic acid copolymer, polypropylene, poly-1-butene, and ionomer; polyvinyl chloride, polyvinylidene chloride, polystyrene, and Vinyl polymers such as acrylonitrile; polyamides such as nylon 6, nylon 66, and nylon 11; polyesters such as polyethylene terephthalate and polybutylene terephthalate; polycarbonate, polyvinyl alcohol, ethylene-
Examples include vinyl alcohol copolymers. These base materials may be uniaxially or biaxially stretched. Further, a film coated with polyvinylidene chloride or a multilayer film made of two or more types may be used.

Next, in the laminated material of the present invention, the multilayer material laminated with the base material via the adhesive layer is made of (A) a polypropylene resin and an ethylene-α-olefin copolymer with a density of 0.900 to 0.950 g/cm ³ This is a multilayer material consisting of a resin composition layer (B) and a polypropylene resin layer (B).

Various types of polypropylene resins can be used as a component in the resin composition layer (A) of the multilayer material used in the present invention, but generally the polypropylene resin has a density of 0.895 to 0.915 g/cm ³ and a melt The index (MI) ranges from 0.5 to 30 g/10 minutes. These polypropylene resins include propylene homopolymers, random copolymers of propylene and 20% by weight or less of other α-olefins (ethylene, butene-1, hexene-1,4-methylpentene-1, etc.), and There are block copolymers. Among these, it is preferable to use a random copolymer with 0.5 to 20% by weight of α-olefin. It should be noted that these polypropylene resins can be used alone or in a mixture of various types. Furthermore, if necessary, a polypropylene resin modified with an unsaturated carboxylic acid or a derivative thereof may be blended.

Next, the ethylene-α-olefin copolymer, which is another component in the resin composition layer (A) layer, is a linear low-density ethylene copolymer obtained by a low to medium pressure method, and has a density of 0.900. ~0.950g/ ^cm3 , MI0.5~30g/
10 minutes, preferably 1 to 20 g/10 minutes. Here, the α-olefin to be copolymerized with ethylene has 3 to 12 carbon atoms, such as ethylene,
Butene-1, Pentene-1, Hexene-1, Octene-1,4-methylpentene-1, Decene-
1, dodecene-1, etc. The content of α-olefin in these copolymers is usually in the range of 2 to 20% by weight. It should be noted that these ethylene-α-olefin copolymers may be used alone or as a mixture of copolymers having different densities and melt indexes.

The composition ratio in a resin composition consisting of a polypropylene resin, which is the layer (A) in the multilayer material, and an ethylene-α-olefin copolymer with a density of 0.900 to 0.950 g/cm ³ is 5 to 80% by weight of the polypropylene resin. and 95 to 20 parts by weight of the ethylene-α-olefin copolymer, preferably 10 to 60 parts by weight of the polypropylene resin and 90 to 40 parts by weight of the ethylene-α-olefin copolymer. Here, if only an ethylene-α-olefin copolymer is used as the layer (A), or if a resin composition of a polypropylene resin and a high-pressure low-density polyethylene resin is used, the laminated material that is the object of the present invention The object of the present invention cannot be achieved because the multilayer material does not have sufficient adhesive strength and delamination occurs between the layers of the multilayer material.

The polypropylene resin (B), which is the other layer of the multilayer material used in the present invention, is the same as the polypropylene resin used in layer (A), and is the same as that used in layer (A). It may be different. Methods for molding this multilayer material include coextrusion molding, extrusion lamination, etc., but usually coextrusion molding, such as coextrusion T-die molding using a flat die, and inflation molding using a circular die. will be adopted.
This multilayer material is basically a two-layer material consisting of (A) and (B), but it can also be made up of three or more layers by laminating layers of the same type or other materials on the outside of the (B) layer. It may also be a multilayer material. Similar materials include propylene-α-olefin copolymer, and other materials include polyethylene, ethylene-α-olefin copolymer, polyester, polyamide, and polycarbonate.

The thickness of this multilayer material is not particularly limited, but it is usually a film of 200μ or less, and the thickness of each layer is 1 to 10μ, preferably 1 to 5μ, the other (B). ) The thickness of the polypropylene resin layer is 5 to 200μ, preferably 5 to 100μ.
Furthermore, heat stabilizers, oxidation stabilizers, weather resistance stabilizers, antistatic agents, antiblocking agents, slip agents, antifogging agents, coloring agents, etc. can be added to the resins for each layer as necessary. Other thermoplastic resins, thermoplastic elastomers, plasticizers, etc. may be added within the range that does not impair the purpose of the present invention.

Next, the laminated material of the present invention is obtained by laminating the above-described base material and the multilayer material via an adhesive layer so that the resin composition layer of the multilayer material faces the surface of the base material.
Here, the adhesive layer is not particularly limited and may be appropriately determined depending on the manufacturing method of the laminated material. For example, reactive adhesives such as polyester polyurethane, polyether polyurethane, epoxy, etc. There are various types of polymers. Here, the ethylene polymers include high-pressure low-density polyethylene, ethylene-α-olefin copolymer, so-called linear low-density polyethylene,
Examples include ethylene-unsaturated carboxylic acid copolymers and ethylene ionomers. Low-density polyethylene resins include those with a density of 0.860 to 0.940 g/cm ³ , preferably 0.880 to 0.930 g/cm ³ , and can be used in a wide range from crystalline polyethylene resins to amorphous polyethylene resins. . It is also possible to add polyolefin resins obtained by modifying these polyethylene resins, polypropylene resins, etc. with unsaturated carboxylic acids such as maleic acid and maleic anhydride, or derivatives thereof. Furthermore, other resins and rubbers may be added to the extent that they do not interfere with the adhesive layer of the present invention. For this adhesive layer, a mixture of two or more types of resins can be used, or two or more types of different layers can be used.

The laminated material of the present invention is obtained by laminating the base material and the multilayer material with an adhesive layer interposed therebetween.
Here, the base material is coated with an anchor coating agent such as polyethyleneimine, organic titanium, isocyanate, etc., using a known method to increase adhesive strength, although this varies depending on the type. , may be laminated.

Examples of laminated materials include a laminated material obtained by the dry lamination method shown in FIG. 1A, and a laminated material obtained by the extrusion lamination method and coextrusion lamination method shown in FIG. 1B.

FIG. 2 shows a manufacturing method using an extrusion lamination method. Here, a multilayer material film is fed out from a multilayer material film feed roll 11, a base material is fed out from a base material feed roll 12, an adhesive resin is extruded from an extrusion die 13 between the two layers, and a pressure roll 14 and a cooling roll are fed out. 15, the laminated material is wound onto a take-up roll 16. When low density polyethylene is used as the adhesive resin, the resin temperature is 250 to 350℃, preferably 280 to 330℃.
℃, and the linear pressure of the pressure roll is 2 to 30 kg/cm, preferably 3 to 20 kg/cm. In the present invention, by using a specific multilayer material for the sealing material layer, sufficient adhesion can be achieved without the need for anchoring of the sealing material layer film, compared to the conventional polypropylene sealing layer. A major feature is that a laminated material with high properties can be obtained. In the figure, 17 is an anchor treatment tank, and 18 is a drying device.

As detailed above, the laminated material of the present invention uses a multilayer material with excellent heat resistance, strength, and transparency similar to that of polypropylene resin, and does not require anchor treatment when manufactured by extrusion lamination. It is hygienic, highly stable, has no foreign odor, and can be manufactured at low cost. In addition, this laminated material has excellent lamination strength and heat sealability, and has characteristics such as heat resistance, strength, and rigidity, and can be used in a wide range of fields as a packaging material for various products such as foodstuffs. You can expect it.

Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples as long as the gist of the present invention is satisfied.

Example [Manufacture of multilayer film] (a) Random polypropylene and a resin composition consisting of 40 parts ^by weight of random ^1* polypropylene and 60 parts by weight of ethylene ^- octene-1 copolymer were each made into a 65 mm diameter film. Extruder (resin temperature 250℃) and
Melt extrusion with a 50mmφ extruder (resin temperature 240℃),
Multi-manifold double-layer T-die (die width
800 mm, die temperature 270°C/250°C), the film was extruded, cooled with a chill roll, and then wound to obtain a two-layer film. The thickness of this film was 25μ, with a polypropylene layer of 23μ and a resin composition layer of 2μ.

*1 (ethylene content 4% by weight, density 0.90g/
cm ³ , MI7g/10min) *2 (density 0.923g/cm ³ , MI4g/10min) (b) () Random polypropylene ^*1 and () Homopolypropylene ^*3 and () Random polypropylene ^*1 Pyrene 40 Weight parts and ethylene-octene-1 ^*2
A resin composition consisting of 60 parts by weight of the copolymer was processed using a 50 mmφ extruder (resin temperature 240°C), a 65 mmφ extruder (resin temperature 250°C), and a 50 mmφ extruder (resin temperature 250°C), respectively.
(240°C), extrusion, cooling with a chill roll, and winding to obtain a 25μ three-layer film. The layer ratio of each layer of the film is ():():()=2:12:1
It was hot.

*3 (density 0.91 g/cm ³ , MI 10 g/10 min) Example 1 A biaxially stretched polypropylene film with a thickness of 30 μm was fed out from a roll as a base material, and a polyethyleneimine anchor coating agent (as a solid content) was applied to the surface.
2.0 to 2.5 g/m ² ) and dried. The two-layer film obtained in Production Example (a) was fed out from the other roll so that the resin composition layer served as the adhesive surface. On the other hand, high-pressure low-density polyethylene (density 0.920 g/cm ³ , MI 7 g/10 min) was extruded between these two films under extrusion conditions of resin temperature 300°C, air gap 80 mm, and die width 500 mm to a thickness of 15 μm. Lamination was carried out at a roll linear pressure of about 4 kg/cm to obtain a laminated film with a thickness of 70 μm.

The lamination strength of the obtained laminated film is 1000
(g/15mm) or more, material failure occurred and no delamination between the multilayer films was observed.

Example 2 A 70 μm laminated film was obtained in the same manner as in Example 1 except that the three-layer film obtained in Production Example (b) was used instead of the two-layer film.

The lamination strength of the obtained laminated film is 1000
(g/15mm) or more, material failure occurred and no delamination between the multilayer films was observed. In addition,
When the multilayer film surface of this laminated film was heat sealed under the following temperature conditions and sealing pressure of 0.4 kg/cm ² , the heat sealing strength was as follows.

140℃ 1600 (g/15mm) 150℃ 2000 (g/15mm) 160℃ 2300 (g/15mm) 170℃ 2500 (g/15mm) Comparative example In Example 1, 25μ was used instead of the double layer film.
A laminated film was obtained in the same manner except that a non-stretched random polypropylene film was used.

The lamination strength of the obtained film was 240 (g/
15mm), heat seal strength at 160℃ is 1300 (g/
15mm).

[Brief explanation of drawings]

FIGS. 1A and 1B are cross-sectional views showing examples of the laminated material of the present invention, and FIG. 2 is an explanatory view showing an example of a method for manufacturing the laminated material. DESCRIPTION OF SYMBOLS 1...Multilayer material, 2, 3...Adhesive layer, 4...Anchor coat layer, 5...Base material, 11...Multilayer material (film) feeding roll, 12...Base material feeding roll, 13...Extrusion die.

Claims (1)

[Claims] 1. In the base material, (A) polypropylene resin and density
A multilayer material consisting of a resin composition layer consisting of an ethylene-α-olefin copolymer of 0.900 to 0.950 g/cm ³ and (B) a polypropylene resin layer is placed so that (A) the resin composition layer faces the substrate surface. A laminated material that is laminated through an adhesive layer. 2 The resin composition is 5 to 80 parts by weight of polypropylene resin and ethylene-α- having a density of 0.900 to 0.950 g/cm ³
The laminated material according to claim 1, which comprises 95 to 20 parts by weight of the olefin copolymer. 3. The laminate material according to claim 1, wherein the adhesive layer is an ethylene polymer having a density of 0.860 to 0.940 g/cm ³ .