JPH0978046A - Adhesive and laminate using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an adhesive having high adhesive strength to a metallic base material and high impact strength by blending a syndiotactic propylene- based polymer having a specific racemic pentad fraction with a modified polymer graft-polymerized of unsaturated carboxylic acids. SOLUTION: The objective adhesive gives a laminate 1 containing a metallic base material by firmly bonding an olefinic polymer 4 with the metallic base material 3 through a layer 5 of the adhesive, gives sufficient adhesive strength by extrusion coating or sandwich lamination and has excellent impact resistance in the bonded part. The adhesive is obtained by graft polymerizing a syndiotactic propylene-based polymer containing >=75% racemic pentad (rrrr) fraction with an ethylenic unsaturated carboxylic acid or its acid anhydride (e.g.; maleic anhydride) to obtain a modified polymer having >=500sec half- crystallization time after keeping at a temperature of (its melting point: Tm+10) deg.C and quenching to 125 deg.C, then mixing the resultant modified polymer into an adhesive.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adhesive having excellent adhesiveness between a metal and a resin, particularly an olefin resin, and a laminate using the same. More specifically, it is highly adhesive by extrusion lamination or heat lamination. Strength is obtained,
Moreover, the obtained laminate relates to an adhesive and a laminate having high seal strength and impact resistance.

[0002]

2. Description of the Related Art Containers made of various materials such as metal, glass, and plastic are generally used for packaging foods and the like, and these plural materials are laminated to combine the features of each material. Laminated containers that are made use of are also used. This laminate has an advantage that various required functions such as excellent gas barrier properties, sealing reliability, strength, and heat sealing properties can be sufficiently brought out depending on the characteristics of each material.

Conventionally, olefin resins such as various polyethylenes and polypropylenes have been widely used as the inner surface material of flexible packaging from the viewpoint of heat-sealing property and hygienic property. On the other hand, for imparting gas barrier property to the packaging. Metals and gas barrier resins are widely used as materials.

Since there is no adhesiveness between the olefin polymer and the metal or gas barrier resin, urethane adhesives or epoxy adhesives are used, and in order to impart thermal adhesiveness Acid-modified olefin resin adhesives are also used as adhesives. Since the acid-modified olefin resin-based adhesive can be melt-extruded, it also provides an advantage that extrusion coating or sandwich lamination is possible.

Japanese Unexamined Patent Publication (Kokai) No. 4-46981 discloses 100 parts by weight of a polypropylene having a syndiotactic structure and an isotactic structure, and a part or all of modified polypropylene 1 to 1 grafted with an unsaturated carboxylic acid or a derivative thereof. An adhesive of 500 parts by weight polypropylene and polar substance is described.

[0006]

[Problems to be Solved by the Invention] The above-mentioned proposal is an adhesive having excellent heat resistance, which is capable of firmly adhering polypropylene and a polar substance without adding an elastomer to the acid-modified polypropylene or even if an elastomer is added in a very small amount. However, this adhesive does not have sufficient adhesive strength by extrusion coating or sandwich lamination, and the heat seal strength of the laminate using this adhesive is generally low, and the adhesive part does not drop. It has the drawback that it is easily destroyed when it is shocked.

Therefore, an object of the present invention is to firmly bond an olefin polymer to a metal substrate, etc., and to obtain sufficient bonding strength by extrusion coating or sandwich lamination, and to have excellent impact resistance of the bonded portion. Another object is to provide an adhesive and a laminate using the same.

Another object of the present invention is to provide a laminate having excellent adhesion and corrosion resistance of a resin coating to a metal substrate, and also excellent heat seal strength and impact resistance. Further, another object of the present invention is to provide a laminate in which a co-extruded olefin polymer and a polar resin for imparting a barrier property are firmly adhered to each other in a multi-layer plastic container formed by hollow molding or sheet molding. To provide.

[0009]

According to the present invention, a racemic pentad (rrrr, sometimes simply abbreviated as r ₄ hereinafter) syndiotactic propylene polymer having a fraction of 75% or more, Provided is an adhesive containing, as a main component, a modified polymer obtained by graft-polymerizing an ethylenically unsaturated carboxylic acid or acid anhydride.

In the present invention, the modified polymer may be composed of a polymer having a half-crystallization time of 500 seconds or more when the temperature is maintained at the melting point (Tm) + 10 ° C. and then rapidly cooled to 125 ° C. Particularly preferred.

Further, according to the present invention, the metal layer and the thermoplastic resin layer or the gas barrier resin layer such as ethylene vinyl alcohol copolymer and the thermoplastic resin layer are bonded with the above adhesive. A laminate is provided which is characterized by:

[0012]

The adhesive of the present invention is a racemic pentad (rrr).
r) A modified polymer obtained by graft-polymerizing an ethylenically unsaturated carboxylic acid or an acid anhydride with a syndiotactic propylene-based polymer having a fraction of 75% or more.

In the repeating unit of α-olefin such as polypropylene in the propylene-based polymer chain, the carbon atom at the base of the side chain alkyl group such as methyl group is an asymmetric carbon, and the arrangement is meso (m). Two types of racemic (r) stereostructures are possible. The racemic pentad fraction (rrrr) means racemic (r) in the polymer chain.
Is a fraction of four of which are lined up, and the measurement is performed by, for example, R.I. C. Ferguson, Macromolecules, 4 , 32
4 (1971), the high resolution proton m
It can be carried out by the method of magnetic resonance (pmr), and in the syndiotactic propylene polymer used in the present invention, this value is preferably 75% or more, particularly 80% or more.

In the present invention, by using the acid-modified polymer of the syndiotactic propylene polymer as an adhesive, not only a strong adhesive force to a metal substrate can be obtained, but also by extrusion coating or sandwich lamination. High laminating strength can be obtained, and the impact resistance of the bonded portion can be remarkably improved.

See the example below. When a maleic anhydride grafted isotactic polypropylene / random polypropylene coextrudate was used for sandwich lamination of aluminum foil and polypropylene inner surface material (Comparative Example 1), 0.2 kgf / 1 without heat treatment
Only a laminate strength of about 5 mm is obtained, and a maleic anhydride grafted isotactic polypropylene and syndiotactic polypropylene blend is used instead of the maleic anhydride grafted isotactic polypropylene in the above coextrudate. Even in the case (Comparative Example 2), a laminate strength of 0.1 kgf / 15 mm is only obtained. On the other hand, when maleic anhydride grafted syndiotactic polypropylene was used instead of the maleic anhydride grafted isotactic polypropylene (Example 1),
Laminate strengths of up to 1.2 kgf / 15 mm are obtained, which is an unexpected effect according to the invention.

Further, in the laminate using maleic anhydride grafted syndiotactic polypropylene (Example 1), as compared with the laminate using maleic anhydride grafted isotactic polypropylene (Comparative Examples 1 and 2). It is also clear that the heat-sealing strength is more than doubled and the bag breakage due to drop impact is effectively suppressed.

The reason why the above-mentioned excellent action is exhibited in the adhesive of the present invention is considered as follows. That is, in the case of the acid-modified resin based on the syndiotactic propylene-based polymer, since the crystallization rate of the base resin is slow, the mobility (mob) of the acid unit during melting and solidification is increased.
ilitity) is kept high for a long time. Further, since the syndiotactic propylene-based polymer has a sparser crystal structure than the isotactic propylene-based polymer, the stress at the adhesive interface is easily relieved. It is considered that these actions combine to obtain high adhesive strength.

The crystallization rate of the acid-modified resin can be evaluated by the above-mentioned half-crystallization time. When this half-crystallization time is 500 seconds or more, excellent adhesive strength can be obtained by extrusion coating or sandwich lamination.

The metal-resin laminate of the present invention is capable of imparting excellent corrosion resistance to a metal, has excellent workability, and is easy to deep-draw into a container or the like. give. Further, even in the ethylene vinyl alcohol copolymer and the propylene-based polymer resin laminate, even at a high blow ratio or a high draw ratio in the hollow molding container, or at a high drawing ratio in the solid phase molding or melt molding of the cup-shaped container, Excellent adhesion strength can be obtained, and it is particularly excellent in drop impact resistance at low temperature and can prevent delamination from occurring.

[0020]

Preferred Embodiment of the Invention

"Adhesive" The adhesive of the present invention is a racemic pentad (rr
rr) A modified polymer obtained by graft-polymerizing an ethylenically unsaturated carboxylic acid or an acid anhydride with a syndiotactic propylene-based polymer having a fraction of 75% or more is a main component.

The syndiotactic propylene-based polymer used as the base resin (trunk polymer) in the present invention is
It has a racemic pentad (rrrr) fraction of 75% or more, especially 80% or more, which is obtained by a method known per se, for example, polymerization of an olefin using a metallocene compound and an aluminoxane compound as a catalyst. .

The syndiotactic propylene polymer is more preferably a homopolymer of propylene, but propylene as the main monomer and ethylene as the comonomer and / or the formula CH ₂ ═CHR (wherein R is Is an alkyl group having 2 to 8 carbon atoms), particularly a copolymer containing less than 15% by weight can be used. Examples of α-olefins other than propylene include butene-1, pentene-1, hexene-1, octene-1, 4-methylpentene-1 and the like, and random copolymers or blocks of these copolymers. It may be a copolymer.

The melt flow rate (MFR) of the syndiotactic propylene-based polymer is not particularly limited, but it is generally preferably in the range of 0.1 to 200 g / 10 min, while the density is 0.85 to 0. 93 g / c
It should be in the range of m ³ .

The unsaturated carboxylic acid or acid anhydride to be graft-copolymerized with the syndiotactic propylene polymer is not limited to these, but the following are used, for example.

Unsaturated carboxylic acid; acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, tetrahydrophthalic acid, bicyclo [2,2,1]
Hept-2-ene-5,6-dicarboxylic acid and the like.

Unsaturated carboxylic anhydrides; maleic anhydride, itaconic anhydride, citraconic anhydride, tetrahydrophthalic anhydride, bicyclo [2,2,1] hept-2-ene-5,6-dicarboxylic anhydride, etc. . Among these,
Maleic anhydride is preferred.

The above-mentioned unsaturated carboxylic acid or acid anhydride is
Used alone or in combination of two or more, the graft ratio is generally 0.0005 to 5% by weight,
In particular, it is preferable to carry out the graft copolymerization in the range of 0.05 to 2.5% by weight.

Graft copolymerization can be obtained by reacting the above syndiotactic propylene polymer with an unsaturated carboxylic acid or acid anhydride in the presence of a radical initiator. The reaction may be carried out as a solution or may be carried out in a molten state. When it is carried out in the molten state, it is most efficient to carry out it continuously in the extruder.

As the radical initiator used in the graft reaction, all initiators used in this type of graft polymerization can be used. Specifically, organic peroxide,
Organic peresters and the like are used, and as examples, benzoyl peroxide, dichlorobenzoyl peroxide, dicumyl peroxide, di-tert-butyl peroxide,
2,5-Dimethyl-2,5-di (peroxybenzoate) hexyne-3,1,4-bis (tert-butylperoxyisopropyl) benzene, lauroyl peroxide, tert-butyl peracetate, 2,5-dimethyl-
2,5-di (tert-butylperoxy) hexyne-3,
2,5-dimethyl-2,5-di (tert-butylperoxy) hexane, tert-butylperbenzoate, tert-
Butyl perphenyl acetate, tert-butyl perisobutyrate, tert-butyl per-sec-octoate, t
Examples thereof include ert-butyl pervivarate, cumyl pervivarate and tert-butyl perdiethyl acetate. These initiators are preferably used in so-called catalytic amounts.

The above acid-modified resin may be used alone as an adhesive, or may be diluted with unmodified syndiotactic polypropylene or syndiotactic copolypropylene with ethylene and / or α-olefin. It may also be used in the form of a so-called blend. Generally, a carbonyl group (= CO) concentration based on an acid or an acid anhydride is 0.01 to 100 m per 100 g of the whole resin.
-Mol, particularly in the range of 0.1 to 50 m-mol, satisfactory adhesive strength, extrusion moldability and heat stability are obtained.

The adhesive of the present invention can be blended with other polymers, fillers, colorants, heat stabilizers, antioxidants and the like, although they are not generally required, but to the extent that the essence thereof is not impaired.

Other polymers include olefin resins other than the syndiotactic propylene polymer of the present invention,
For example, low-, medium- or high-density polyethylene, isotactic polypropylene, linear low density polyethylene, ethylene-propylene copolymer, polybutene-1,
Ethylene-butene-1 copolymer, propylene-butene-
1 copolymer, ethylene-propylene-butene-1 copolymer, ethylene-vinyl acetate copolymer, ion-crosslinked olefin copolymer (ionomer), ethylene-acrylic acid ester copolymer, etc .; elastomeric polymer such as nitrile -Butadiene rubber (NBR), styrene-butadiene rubber (SBR), chloroprene rubber (CR), polybutadiene (BR), polyisoprene (IR), butyl rubber, natural rubber, ethylene-propylene rubber (EPR),
Ethylene-propylene-diene rubber (EPDM), polyurethane, silicone rubber, acrylic rubber, etc .; thermoplastic elastomers such as styrene-butadiene-styrene block copolymers, styrene-isoprene-styrene block copolymers, hydrogenated styrene-butadiene-styrene. Examples thereof include block copolymers and hydrogenated styrene-isoprene-styrene block copolymers. These other polymers should be 30% by weight or less per adhesive.

The adhesive of the present invention is heat activated to bond the two parts together. This adhesive can be used in any form such as powder, film, tape, melt, dispersion (dispersion) and the like for bonding metal and resin, particularly olefin resin. For example, it is possible to form an adhesive layer on a substrate by applying an adhesive powder to a substrate such as a metal by means of fluidized dipping or the like, or to disperse fine particles of the adhesive in an organic solvent or an aqueous medium. The liquid can be applied to a substrate such as metal and heat-treated as necessary to form an adhesive layer. Of course, it can be applied to the substrate in advance in the form of a film, a tape or the like, or it can be used for adhesion by interposing the substrate with the olefin resin layer. Further, it can also be used for adhesion by extrusion in a molten state, extrusion coating, sandwich lamination and the like. Further, as a composite paint in which the above-mentioned dispersion is added to an epoxy paint, it can be used for adhesion by coating it on a metal substrate, baking and drying it, and then interposing it between an olefin resin and the same as a usual paint.

"Laminate" In another aspect of the present invention, there is provided a laminate obtained by bonding a metal substrate and a resin, particularly an olefin resin, with the above adhesive.

In FIG. 1 showing a preferred example of the laminate of the present invention, this laminate 1 has a resin protective layer 2 on the outer surface.
The metal substrate 3 on which is formed and the olefin resin layer 4 are adhered to each other via an adhesive layer 5 containing an acid-modified syndiotactic propylene polymer.

In FIG. 2 showing another preferred example of the laminate of the present invention, the laminate 1 is shown in FIG. 1 except that the resin protective layer 2 on the outer surface is adhered to the metal substrate 3 through the adhesive layer 6. Is the same as. In this case, the resin protective layer 2 on the outer surface
May be an olefin resin layer, and the adhesive layer 6
May be an acid-modified syndiotactic propylene polymer.

As the metal base 3, various surface-treated steel plates or foils or light metal plates or foils of aluminum or the like are used.

As the surface-treated steel sheet or foil, cold-rolled steel sheet is annealed and then secondary cold-rolled, and one or two kinds of surface treatment such as zinc plating, tin plating, nickel plating, electrolytic chromic acid treatment and chromic acid treatment. What was performed above can be used. An example of a suitable surface-treated steel sheet or foil is an electrolytic chromic acid-treated steel sheet or foil, particularly 10 to 200 mg / m 2.
^{It is provided with} a metallic chromium layer of No. ^{2 and} a chromium oxide layer of 1 to 50 mg / m ² (as metallic chromium), and this one has an excellent combination of adhesion with a resin and corrosion resistance. Another example of surface treated steel foil is 0.6 to 11.2 g /
A hard tin foil having a tin plating amount of m ² . This tin foil has a chromium content of 1 to 30 m in terms of metallic chromium.
It is desirable that the chromic acid treatment or the chromic acid / phosphoric acid treatment is performed so as to obtain g / m ² .

As the light metal plate or foil, in addition to the so-called pure aluminum plate or foil, an aluminum alloy plate or foil is used. Aluminum alloy sheets or foils excellent in corrosion resistance and workability include Mn: 0.2 to 1.5% by weight, Mg:
0.8 to 5% by weight, Zn: 0.25 to 0.3% by weight, and Cu: 0.16 to 0.26% by weight, balance A
It has a composition of 1 l. These light metal plates and foils also have a chromium content of 20 to 300 mg in terms of metal chromium.
It is desirable that the chromic acid treatment or the chromic acid / phosphoric acid treatment is performed so that the amount becomes / m ² .

The thickness of the metal plate or foil varies depending on the kind, use or size of the metal, but is generally 3 to 15.
It preferably has a thickness of 0 μm, especially 5 to 120 μm.

The protective coating film 2 on the metal substrate is a thermosetting resin coating material such as phenol-formaldehyde resin, furan-formaldehyde resin, xylene-formaldehyde resin, ketone-formaldehyde resin, urea-formaldehyde resin, melamine-formaldehyde resin. , Alkyd resin, unsaturated polyester resin, epoxy resin, bismaleimide resin, triallyl cyanurate resin, thermosetting acrylic resin, silicone resin, oil resin, or thermoplastic resin coating, for example, vinyl chloride-vinyl acetate copolymer Examples thereof include a polymer, a vinyl chloride-maleic acid copolymer, a vinyl chloride-maleic acid-vinyl acetate copolymer, an acrylic polymer, and a saturated polyester resin. These resin paints may be used alone or in combination of two or more. These coatings generally have a thickness of 1 to 30 μm,
In particular, it is preferable that the thickness is 3 to 15 μm.

Further, as the resin protective layer 2 provided on the metal substrate via the adhesive, a film of a thermoplastic resin known per se, for example, an olefin resin described later, nylon 6, nylon 6-6, nylon is used. Examples thereof include polyamides such as 6-10, nylon 11 and nylon 12, thermoplastic polyesters such as polyethylene terephthalate and polybutylene terephthalate, and single or plural films of polycarbonate and the like. These resin films may be unstretched or may be uniaxially or biaxially stretched. The thickness of these single film or a plurality of films is preferably in the range of 5 to 200 μm, particularly 10 to 120 μm as a whole.

As the adhesive used for adhering the metal and the film, it goes without saying that the acid-modified syndiotactic propylene polymer according to the present invention can be used, but in addition, urethane adhesive, epoxy adhesive, A general acid-modified olefin resin or the like can be used.

The olefin resin layer 4 provided on the other surface of the metal substrate is, for example, low-, medium- or high-density polyethylene, isotactic polypropylene, syndiotactic polypropylene, or ethylene or α-olefin thereof. A polypropylene-based polymer which is a copolymer with, a linear low-density polyethylene, an ethylene-propylene copolymer, a polybutene-1, an ethylene-butene-1 copolymer, a propylene-butene-1 copolymer,
Examples thereof include an ethylene-propylene-butene-1 copolymer, an ethylene-vinyl acetate copolymer, an ion-crosslinked olefin copolymer (ionomer), and an ethylene-acrylic acid ester copolymer. These may be used alone or in combination of two or more. Can be used in the form of a blend, and can be used in a single layer or in a multilayer of two or more layers. Olefin-based resins are particularly advantageous for the purpose of the present invention because they have excellent moisture resistance and heat-sealing properties. The thickness of the olefin resin layer varies depending on the use, but is generally 15 to 2
It is preferably in the range of 00 μm, particularly 30 to 160 μm.

The laminate of the present invention can be produced by a means known per se such as extrusion coating or sandwich lamination. It is natural that the heat adhesion is performed at a temperature equal to or higher than the melting point (Tm) of the acid-modified syndiotactic propylene polymer, but generally Tm + 3 ° C. to Tm +.
A temperature of 150 ° C is suitable.

For example, a coextrusion laminate of an acid-modified syndiotactic propylene polymer and an olefin resin is provided on the other surface of a metal substrate having one surface protected and coated, and the metal substrate and the acid-modified resin face each other. Extrusion coating,
A laminate can be manufactured by pressing this.

A metal substrate having one surface protected and an olefin resin film are produced in advance, and an acid-modified syndiotactic propylene polymer layer is extruded or acid-modified between them. A coextrusion laminate of a syndiotactic propylene polymer and an olefin resin is extruded so that the metal substrate and the acid-modified resin face each other and the extruded olefin resin layer and the olefin resin face each other, A laminate can also be manufactured by sandwich lamination in which these are pressed together.

The thickness of the acid-modified syndiotactic propylene polymer adhesive layer is generally in the range of 1 to 50 μm, and preferably 3 to 20 μm in terms of adhesiveness.

The adhesive according to the present invention is particularly effective for adhesion between a metal substrate and an olefin resin, but the adhesive can of course be used for other purposes, for example, a gas barrier resin in a packaging laminate. Can be used for adhesion between olefin resin and Also, when scrap-returning non-adhesive multi-layer resin such as gas barrier resin and olefin resin is used as one component of container material, its physical properties such as moldability, mechanical properties and optical properties are improved. For this purpose, this adhesive can be used by mixing it in a required predetermined amount.

As the gas barrier resin, ethylene-
A vinyl alcohol copolymer can be mentioned, for example, an ethylene-vinyl acetate copolymer having an ethylene content of 20 to 60 mol%, particularly 25 to 50 mol%,
A saponified copolymer obtained by saponification so that the saponification degree is 96 mol% or more, particularly 99 mol% or more is used. The saponified product of the ethylene-vinyl alcohol copolymer should have a molecular weight sufficient to form a film, and generally has a molecular weight of 0.1% as measured at 30 ° C. in a mixed solvent of 85:15 by weight of phenol: water. It is desirable to have a viscosity of 01 dl / g or more, particularly 0.05 dl / g or more.

As another example of the gas barrier resin, the number of amide groups per 100 carbon atoms is 5 to 50.
Polyamides in the range of 6 to 20 in particular; eg nylon 6, nylon 6.6, nylon 6/6/6 copolymer, metaxylylene adipamide, nylon 6/10, 10,
Semi-aromatic polyamides such as nylon 11, nylon 12, nylon 13, hexamethylene terephthalamide / isophthalamide, etc. are used. These polyamides should also have a molecular weight sufficient to form a film, and have a relative viscosity (ηrel) of 1.1 or more, measured at a concentration of 1.0 g / dl in concentrated sulfuric acid and a temperature of 30 ° C., especially 1. It is preferably 5 or more.

The above gas barrier resin generally varies from 1 to 50 though it varies depending on the amount of oxygen allowed in the package.
It is desirable to have a thickness of μm, particularly 30 μm.

The gas barrier resin (A) and the olefin resin (B) are combined through the adhesive (C), and the layer structure is as shown in FIG. A / C / B, B / C / A, as shown as a typical laminate 7 in a and b.
/ C / B, B / (B + C + A) / C / A / C / B, B /
The layer structure may be (B + C + A) / C / A / C / (B + C + A) / B. In the layer structure, (B + C + A) indicated by 9 means a scrap resin containing the resin component. The thickness of the olefin resin (B) and the adhesive (C) may be the same as in the metal laminate.

The laminate according to the present invention is useful as a packaging material for cans, lids, pouches, bottles, cups, trays, etc .; mechanical parts such as various panels, casings, housings; various interior materials or exterior materials.

[0055]

The present invention will be described in the following examples. Example 1 Here, using the adhesive resin of the present invention, biaxially stretched polyethylene terephthalate (BO-PET, 12 μm / aluminum foil (AL), 7 μm / coextruded laminated resin layer, 10 μm / internal unstretched polypropylene (CPP). ),
After making a laminated packaging film consisting of 60 μm, a pouch with an internal capacity of about 170 ml (outer size 125 ×
The performance was evaluated as 160 mm). The laminate was prepared through the process sequence described below. First, BO-PET and aluminum foil, which had been subjected to normal gravure printing on the inner surface side, were dry-laminated with a urethane solvent adhesive, and then cured at 55 ° C. for 3 days. Next, this BO-PET / AL was held on a backup roll. Then, the adhesive resin of the present invention and the random polypropylene resin (MFR13) were extruded at 3 μm and 7 μm at a resin temperature of 280 ° C., and an inner surface CPP (block polypropylene, MFR1.5) film was placed at 80 ° C. from the opposite side.
Sandwich lamination was performed using the chill roll that was temperature-controlled. In Table 1, this case is shown as no heat treatment, but a laminate subjected to heat treatment of two levels L and H was prepared as a comparison. Under the heat treatment condition L, the BO-PET surface of the laminate having the above-mentioned structure is heated with a heater roll (set temperature 180 ° C., diameter 1000 mm).
Heat treatment was performed at 0 m / min so that the surface of the CPP was 125 ° C. In the heat treatment condition H, a floating oven (set temperature 180 ° C., length 10 m) was used, and
Heat treatment was performed at 0 m / min so that the peak temperature of the laminate was 175 ° C. From these laminates,
Using an automatic high-speed bag making machine, pouches having a predetermined size were prepared at a speed of 125 bags / row per minute. With respect to these pouches, laminate strength and heat seal strength were measured and evaluated at 10 points each in the vertical and horizontal directions. For drop bag strength, use water 15
After pouch sealing after 0 ml filling and sterilization at 125 ° C for 30 minutes and then left at 5 ° C, put the pouch in a special cosmetic box and pack it in a carton of 40 boxes. After dropping, the number of broken bags was checked, and the ratio of the number of non-defective products was checked. Furthermore, regarding content resistance, water, salad oil, ketchup,
After filling and sealing 150g of 1: 1: 1 mixture of
After retort sterilization at 5 ° C. for 30 minutes and storage at 37 ° C. for 1 month, the presence or absence of internal delamination and aluminum corrosion was evaluated. Table 1 shows these results.

In the conventional adhesive containing isotactic PP as the trunk resin (Comparative Example 1) or the adhesive containing the same as the main component (Comparative Example 2), the crystallization rate of the adhesive resin is high, so that the adhesive is not solidified by cooling. Until then, the adhesive strength with the aluminum foil is not developed and sufficient performance as a laminate cannot be obtained. Further, although a certain degree of laminate strength can be secured by applying heat treatment, sufficient drop bag strength cannot be achieved, and corrosion at the aluminum interface is also below the practical level. On the other hand, with the adhesive resin of the present invention (Invention 1) or the adhesive resin containing the same as the main component (Invention 2), by selecting the laminating conditions as described above without performing a special heat treatment,
Laminate performance close to practical level can be obtained. When used as a pouch, the heat seal strength tends to be slightly lower,
By performing a heat treatment that does not reduce the drop bag strength, more stable laminating performance is realized.

[0057]

[Table 1]

Example 2 Here, the effect of changing the concentration of maleic anhydride as a modifier of syndiotactic PP and the grafting ratio was examined. The performance of the draw-formed container used was evaluated. As a laminate structure, unstretched PPII (containing about 12% of TiO ₂ ), 40 μm / adhesive resin co-extrusion laminate layer II, 10 μm / surface chrome,
Chromated steel foil, 75 μm / adhesive resin co-extrusion laminate layer I, 10 μm / unstretched PPI (Ti
O ₂ content of about 10%), 40 μm. Example 1 above
The adhesive of the present invention, 3 μm / random PP
(MFR13) Extruded at a resin temperature of 280 ° C. and 80 m / min so that the adhesive layer will be on the steel foil side with a structure of 7 μm, and sandwich-laminated first with no stretched PPI on the inner surface side and then with unstretched PPII on the outer surface side. went. Here, the steel foil was heated to about 80 ° C. by contacting it with a heating roll in advance. Further, in order to further improve the adhesiveness of the adhesive resin, under the above conditions, the temperature of the steel foil is about 120 ° C. (heat treatment condition L), further, the lamination of the layer I is under the condition of L, and the layer II is under Conditions where the temperature of the steel foil is about 150 ℃ (same H)
Lamination was done even in. While laminating strength (average of 5 points for each of MD and TD) was evaluated for these composite materials, as shown in JP-B-4-31937,
A deep drawn cup with a flange having a diameter of 65 mm, a bottom diameter of 66 mm and a height of 40 mm was formed by a punch made of a rubber elastic body and a normal die, and the forming workability was evaluated. Further, the heat seal strength of the flange portion of the obtained cup was measured with a lid member made of a non-stretched PP heat seal material. Further, 80 ml of 10-fold diluted vinegar was filled and sealed, sterilized by retort for 30 minutes at 125 ° C., and then stored at 37 ° C. for 1 month, and the amount of hydrogen generated in the head space in the container was evaluated. Table 2 shows these results.

When the graft ratio was less than 0.0005 (Comparative Example 4), the laminating strength to withstand the molding process was not achieved, and the peeling defects on the side wall frequently occurred during molding. Also, even if it can be molded, sufficient heat seal strength cannot be obtained,
It cannot withstand retort sterilization. Further, even if the graft ratio was as low as that of the present invention 7, a laminate strength that could withstand the molding process could be obtained, but the hydrogen generation amount slightly increased, and the resistance to contents was liable to decrease. On the other hand, when the graft ratio exceeds 5% (Comparative Example 3), foaming occurs at the time of laminating, rather the laminating strength is rather lowered, or film defects occur due to this foaming at the time of molding, which is an index of the degree of metal exposure. The lator value (ERV) tends to be high. In addition, the amount of hydrogen generated is remarkably increased accordingly. As shown in the present inventions 4 and 5, when the graft ratio is in the range of 0.05 to 2.5 wt%,
Even under comparatively gentle laminating conditions, it exhibited excellent moldability and resistance to content.

[0060]

[Table 2]

Example 3 As the trunk resin of the adhesive resin, those having different syndiotacticity (Invention 8 to 10, Comparative Example 5), and by changing the addition amount of dibenzylidene sorbitol as the crystal nucleating agent, Regarding the influence on the laminate performance when the crystallization rate of the resin was changed, a laminate packaging film having the same structure as in Example 1 was prepared and evaluated as a pouch. The results are shown in Table 3. As the syndiotacticity decreases, the laminate strength tends to decrease, and the drop resistance also decreases accordingly. In addition, the content resistance was also deteriorated due to blister formation. When the nucleating agent is added to increase the crystallization rate, the laminate strength is lowered and the drop-bag resistance is also slightly lowered.

[0062]

[Table 3]

Example 4 Using the adhesive resin of the present invention, PP / adhesive resin / EVOH
A three-type, five-layer direct blow bottle (capacity 420 ml) composed of / adhesive resin / PP was prepared, and the adhesive strength (laminate strength) and the container performance (such as delamination when dropped) were evaluated. Table 4 shows the results. Where P of the inner and outer layers
As the P resin, MFR 2.0, isotactic PP having a density of 0.903, as the barrier layer EVOH, ethylene content 32%, MFR 1.3, melting point 183 ° C.,
Each resin is used at 210 to 220 ° C. with an inner / outer layer of 350 μm, an adhesive layer of 50 μm, and a barrier layer of 50 μm.
mm, blow-up ratio 2.7, blow pressure 6.5 kgf /
Extrusion blow molding was performed at cm ² and a mold temperature of 15 ° C.
In the adhesive resin that uses isotactic PP as the trunk resin,
The laminating strength tends to be low in a thin portion having a high blow ratio, and peeling easily tends to proceed in the thick portion near the shoulder and bottom when dropped. On the other hand, the adhesive resin made of syndiotactic PP of the present invention shows stable laminate strength in each part of the bottle and stable adhesive property without peeling even when dropped.

[0064]

[Table 4]

[0065]

According to the present invention, racemic pentad (r
rrr) A modified polymer obtained by graft-polymerizing an ethylenically unsaturated carboxylic acid or an acid anhydride with a syndiotactic propylene polymer having a fraction of 75% or more is used as an adhesive to obtain an olefin polymer and a metal substrate. It is possible to obtain an adhesive structure that can be firmly adhered to the above, and that has sufficient adhesive strength by extrusion coating or sandwich lamination and that has excellent impact resistance at the adhesive portion. Further, the obtained laminate has an advantage that it is excellent in adhesion to a resin-coated metal substrate and corrosion resistance, and also excellent in heat seal strength and impact resistance.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of a sectional structure of a laminate of the present invention.

FIG. 2 is a sectional view showing another example of the sectional structure of the laminate of the present invention.

FIG. 3 is a sectional view showing an example including a barrier resin layer in the sectional structure of the laminate of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Laminate containing a metal substrate 2 External resin protective layer 3 Metal substrate 4 Olefin-based resin layer 5 Adhesive layer containing acid-modified syndiotactic polypropylene 6 Adhesive layer 7 Laminate containing a barrier resin layer 8 Barrier resin layer 9 Scrap layer

Claims (6)

[Claims] 1. A racemic pentad (rrrr) fraction of 75.
% Or more of syndiotactic propylene polymer,
An adhesive comprising a modified polymer obtained by graft-polymerizing an ethylenically unsaturated carboxylic acid or acid anhydride. 2. The melting point (Tm) + of the modified polymer.
The adhesive according to claim 1, which is made of a polymer having a half-crystallization time of 500 seconds or more when it is rapidly cooled to 125 ° C after being kept at a temperature of 10 ° C. 3. The adhesive according to claim 1, wherein the syndiotactic propylene-based polymer is polypropylene. 4. A syndiotactic propylene polymer is propylene as a main monomer and ethylene as a comonomer and / or a formula CH ₂ ═CHR (wherein R is an alkyl group having 2 to 8 carbon atoms). ) The adhesive according to claim 1, which is a copolymer containing less than 15% by weight. 5. A laminate characterized in that a metal layer and a thermoplastic resin layer are adhered by the adhesive according to claim 1 or 2. 6. A laminate comprising an ethylene vinyl alcohol copolymer layer and a thermoplastic resin layer adhered to each other with the adhesive according to claim 1 or 2.