JPH02190B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a polyolefin laminate having excellent gas barrier properties. Polyolefins are used in a wide range of applications because, in addition to their low cost, they have excellent mechanical properties, optical properties, thermal properties, chemical properties, and ease of molding. However, due to the lack of gas barrier properties and oil resistance, for example, when used as a food container such as a bottle or can, oxygen gas permeates through and the contents become rancid, or when used as a gasoline container. , the container may become deformed due to swelling,
Furthermore, when used as a detergent container, problems such as stress cracking occur. In order to improve this shortcoming, various measures have been taken in the past. That is, improvements by modifying the polyolefin itself, improvements by using copolymers, etc. have been proposed, but it is difficult to obtain the desired effect. In addition, solutions have been proposed as surface processing techniques for polyolefin, such as applying a special resin as an emulsion or bonding using an adhesive, but these methods require complicated manufacturing operations and are extremely costly. However, there is a need for improvements in order to obtain the desired effects. Therefore, recently, polyolefin laminates, in which polyamides, thermoplastic polyesters, or saponified products of ethylene-vinyl acetate copolymers are strongly bonded and laminated to polyolefins, which have gas barrier properties and oil resistance that polyolefins originally lack, have been developed, especially gasoline. There is a demand for hollow containers such as containers,
The problem of adhering lyolefins to polyamides, thermoplastic polyesters, or saponified products of ethylene-vinyl acetate copolymers has not yet been sufficiently solved. As expected from its chemical structure, polyolefin has almost no polar atomic groups and is chemically inert. This is because the adhesive strength is almost zero, and there is a drawback that if the two are simply fused and laminated, they will peel off. An object of the present invention is to provide a laminate in which a saponified product of polyamide or ethylene-vinyl acetate copolymer is strongly adhered to polyolefin among these resins and has both gas barrier properties and oil resistance. That is, in the present invention, when laminating polyolefin (A) and resin (B) selected from polyamide and saponified products of ethylene-vinyl acetate copolymer,
As an adhesive between these two layers, a composition containing 0.5 to 99.5 parts by weight of a modified polyolefin containing 0.01 to 10% by weight of an unsaturated carboxylic acid or its anhydride and 99.5 to 0.5 parts by weight of a thermoplastic polyester is used. This is a method for producing a laminate, which is characterized by melting and adhering the laminate. The polyolefin (A), which is one of the adherends used in the present invention, includes ethylene, propylene, 1-butene, 1-pentene, 1-3-methylbutene,
α- of hexene-1,4-methylpentene-1, etc.
Single or copolymers of olefins, or copolymers mainly composed of these α-olefins, such as low-density polyethylene, high-density polyethylene, isotactic polypropylene, ethylene-propylene copolymers, ethylene-acetic acid. Vinyl copolymers and the like are used. The following saponified polyamide or ethylene-vinyl acetate copolymer is suitable for use as the other adherend (B). Polyamide is a linear synthetic polymer having an acid amide bond obtained by (a) condensation of diamine and dicarboxylic acid, (b) condensation of amino acid, or (c) ring opening of lactam, such as nylon (polycaptamide), Nylon 6/6 (polyhexamethylene adiphamide), nylon 6/10 (polyhexamethylene sebacamide), nylon 11 (polyundecamide), nylon 12, etc. can be used. In addition, as a saponified product of ethylene-vinyl acetate copolymer, although its chemical composition is not limited, ethylene with an ethylene content of 25 to 50 mol% is recommended, considering gas barrier properties, oil resistance, and water vapor permeability. - Those obtained by saponifying a vinyl acetate copolymer to a degree of saponification of 93% or more, preferably 96% or more are preferred. Next, the modified polyolefin in the adhesive used between these two adherends is prepared by graft polymerizing both the polyolefin and the unsaturated carboxylic acid or its anhydride as mentioned above for polyolefin (A). This can be obtained by adding Here, as the unsaturated carboxylic acid or its anhydride, acrylic acid, maleic acid, itaconic acid,
It is preferable to use hymic acid or anhydrides thereof, particularly maleic anhydride and acrylic acid.
Amorphous 1,2-polytadiene with maleic anhydride added to the tertiary carbon position may also be used. As a modification method by graft polymerization of polyolefin and unsaturated carboxylic acid or its anhydride,
It can be done by a conventionally known method, for example,
38-23494, 43-18393, and 44-9908, methods of irradiation with ionizing radiation or ultraviolet rays, methods of using radical initiators, and methods of peroxidation by the action of oxygen, ozone, or heat. Graft initiation methods such as a method using heat and shear force in a kneader are used. This graft polymerization can be carried out in a commonly used form such as a solution state, a slurry state, or a molten state. The modified polyolefin thus obtained to which 0.01 to 10% by weight of an unsaturated carboxylic acid or anhydride thereof is added is used in the present invention. This modified polyolefin also includes a composition obtained by further adding an unmodified polyolefin to dilute it. In that case, the amount of modified polyolefin in the polyolefin, which is a combination of unmodified polyolefin and modified polyolefin, should be such that the concentration of unsaturated carboxylic acid or its anhydride in the total polyolefin is 0.01% by weight or more in order to obtain at least practical adhesive strength. A certain amount is required. A composition containing such a modified polyolefin and the following thermoplastic polyester is used as an adhesive in the present invention. Thermoplastic polyesters are those obtained by condensation of saturated dibasic acids and glycols, such as polyethylene terephthalate obtained from ethylene glycol and terephthalic acid, phthalic acid, isophthalic acid, sebacic acid, adipic acid, azelaic acid, and glutaric acid. , polyethylene terephthalate copolymers containing saturated dibasic acids such as succinic acid and oxalic acid as copolymer components, and polyethylene containing 1,4-cyclohexanedimethanol, diethylene glycol, propylene glycol, etc. as diol components. Terephthalate copolymers or blends thereof are suitable. In particular, polyethylene terephthalate is preferred because it is inexpensive and easy to mold. The proportion of thermoplastic polyester in this adhesive composition is from 0.5 to 99.5% by weight, and the proportion of modified polyolefin is from 0.5 to 99.5% by weight. If the amount of modified polyolefin is less than 0.5% by weight, or if the amount of thermoplastic polyester is more than 99.5% by weight, the adhesiveness with polyolefin will be impaired. Conversely, if the amount of modified polyolefin is 99.5% or more or the thermoplastic polyester is less than 0.5% by weight, the adhesiveness with the resin that imparts gas barrier properties will be impaired. Although other components other than those mentioned above may be added to such an adhesive, in particular, this adhesive 100%
Adhesiveness can be further improved by adding 1 to 10 parts by weight of ethylene-propylene rubber or ethylene-propylene terpolymer to the adhesive. In addition, when the amount of polyolefin blended into the thermoplastic polyester is small, modified polyolefin may be used as the polyolefin so that the concentration of unsaturated carboxylic acid or its anhydride is 10% by weight, but If the blending ratio of polyolefin becomes large, moldability in melt extrusion etc. may be impaired.
It is preferable to blend the polyolefin so that the concentration of the unsaturated carboxylic acid or its anhydride is 1% by weight or less. An adhesive composition consisting of a modified polyolefin (including one blended with an unmodified polyolefin if necessary) and a thermoplastic polyester is produced by melt-kneading using a conventional kneading machine such as an extruder, a Banbury mixer, or a roll. Ru. Using this adhesive composition, the target polyolefin (A) and a saponified product of polyamide or ethylene-vinyl acetate copolymer (B) are melt-laminated. This melt lamination method is a die lamination method in which polyolefin (A) and polyamide or a saponified product of ethylene-vinyl acetate copolymer (B) and an adhesive composition are simultaneously melt-laminated in a die. This is carried out by a known method such as a lamination molding method in which a sheet of saponified vinyl copolymer is laminated with a sheet of extruded molten adhesive composition. Example 1 0.8 parts by weight of benzoyl peroxide and 1.2 parts by weight of maleic anhydride were added to 100 parts by weight of powder of polypropylene (MI 0.8, specific gravity 0.91), and mixed in a Henschel mixer to obtain a powder with a diameter of 100 mm and L/D. The mixture was extruded at 220°C using a No. 28 extruder, cooled with water, and then pelletized. After dissolving this modified polypropylene in boiling xylene and reprecipitating it with a large amount of acetone, the concentration of maleic anhydride in the modified polypropylene was measured using infrared absorption spectroscopy, and it was found to be 0.67.
It was in weight%. 10 parts by weight of this modified polypropylene, 89.5% by weight of unmodified polypropylene (MI3, specific gravity 0.91) and 0.5 parts by weight of linear polyester (Pylon 200 manufactured by Toyobo Co., Ltd.)
Part by weight of the mixture was extruded into a strand at 250° C. using an extruder having a diameter of 65 mm and L/D of 28, cooled with water, and then cut to obtain pellets. Using this pellet as an adhesive, a laminated film of polypropylene (MI9, specific gravity 0.91)/adhesive layer/nylon 6 was molded by in-die lamination molding (the thickness of the laminated film was 65μ/10μ/10μ). Adhesive layer of obtained laminated film/nylon 6
The interlayer peel strength between the two layers was 0.4 Kg/15 mm, and the polypropylene/adhesive layer could not be peeled off. However, to determine the interlayer peel strength, cut a 15 mm wide test piece from the sample, grasp both layers with the chuck of an Instron testing machine, and check the adhesive strength between the adhesive layer and the gas barrier layer using a T-type (peel) test. Ta. Example 2 10 parts by weight of the maleic anhydride-modified polypropylene used in Example 1, unmodified polypropylene (MI3,
A mixture of 65.5 parts by weight of specific gravity 0.91), 0.5 parts by weight of linear polyester (Pylon 200), 20 parts by weight of low density polyethylene (MI4, specific gravity 0.92) and 4 parts by weight of ethylene-propylene-polymer was prepared with a diameter of 65 mm.
The mixture was extruded into strands at 250° C. using an extruder with L/D of 28, cooled with water, and then cut to obtain pellets. Using this pellet as an adhesive, a laminated film of polypropylene (MI9, specific gravity 0.91)/adhesive layer/nylon 6 was molded by in-die lamination molding (the thickness of the laminated film was 65μ/10μ/10μ). Adhesive layer of obtained laminated film/nylon 6
The interlayer peel strength between the two layers was 0.8 kg/15 mm, and the polypropylene/adhesive layer could not be peeled off. Example 3 Polypropylene/polypropylene/
A laminated film of adhesive layer/saponified ethylene-vinyl acetate copolymer was obtained. The peel strength between the adhesive layer and the saponified material of the obtained laminated film was 0.3 kg/15 mm, and the peel strength between the adhesive layer and the saponified material was 0.3 kg/15 mm, and the
The adhesive layer could not be peeled off. Comparative example 1 99.5 parts by weight of polypropylene (MI3, specific gravity 0.91),
A mixture consisting of 0.5 parts by weight of the linear polyester used in Example 2 was used in an extruder with a diameter of 65 mm and an L/D of 28.
The mixture was extruded into strands at a pressure of 230 mm, cooled with water, and then cut into pellets. Using this pellet as an adhesive, a laminated film of polypropylene (MI9, specific gravity 0.91)/adhesive layer/nylon 6 was molded by in-die lamination molding (the thickness of the laminated film was 65μ/10μ/10μ). Adhesive layer of obtained laminated film/nylon 6
The interlayer peel strength was 0 kg/15 mm. Comparative Example 2 10 parts by weight of the modified polypropylene obtained in Example 1, unmodified polypropylene (MI 0.8, specific gravity 0.91)
66 parts by weight, low density polyethylene (MI4, specific gravity
0.92) and 4 parts by weight of ethylene-propylene rubber (ethylene content 50% by weight, Mooney viscosity 40) was used as an adhesive to form a laminated film of polypropylene (MI9, specific gravity 0.91)/adhesive layer/nylon 6. The thickness was 65μ/10μ/10μ) by the in-die lamination method. Adhesive layer of obtained laminated film/nylon 6
The interlayer peel strength was 0.2 kg/15 mm. Example 4 Polypropylene/adhesive layer/saponified ethylene-vinyl acetate copolymer was prepared in the same manner as in Example 2 except that a saponified ethylene-vinyl acetate copolymer (EVAL) was used instead of nylon 6. A laminated film was obtained. The peel strength between the adhesive layer and the saponified material of the obtained laminated film was 0.6 kg/15 mm. Example 5 10 parts by weight of modified polypropylene obtained in Example 1, unmodified polypropylene (MI 0.5, specific gravity 0.90)
65.5 parts by weight, low density polyethylene (MI0.5, specific gravity
0.92) 20 parts by weight, ethylene-propylene rubber 4
Weight parts and linear polyester (Pylon 200)
0.5 parts by weight were mixed and extruded into a strand at 250° C. using an extruder with a diameter of 65 mm and L/D of 28, and after water cooling, cutting was performed to obtain pellets. Using this pellet as an adhesive, a container with a laminated structure of polypropylene (MI 1.0, specific gravity 0.90)/adhesive layer/nylon 6 was molded using a three-layer in-die lamination blow molding method (average wall thickness: 0.6 mm/50μ). /50μ). A strip with a width of 15 mm was prepared from this laminated container, and the interlayer peel strength between the adhesive layer and nylon 6 was measured and found to be 1.5 kg/15 mm. Example 6 Comparative Examples 3 and 4 After adding 0.6 parts by weight of 3,5,5-trimethylhexanoyl peroxide and 0.9 parts by weight of maleic anhydride to 100 parts by weight of powder of high-density polyethylene (MI 0.5, specific gravity 0.96), Mixed using a Henschel mixer and then using an extruder with a diameter of 40 mm and L/D of 28.
It was extruded into strands at 220°C, cooled with water, and then cut to obtain pellets. After reprecipitating the modified high-density polyethylene pellets in toluene-acetone, the maleic anhydride content was determined by infrared absorption spectrometry to be 0.6% by weight. 10 parts by weight of pellets of this modified polymer, 89.5 parts by weight of unmodified high-density polyethylene (MI 0.3, specific gravity 0.95) and 0.5 parts by weight of linear polyester (Vylon 200).
The weight parts were mixed and extruded into a strand at 200°C using an extruder having a diameter of 40 mm and L/D of 28, and after cooling with water, was cut to obtain pellets. Using this pellet as an adhesive, a laminated hollow container of high density polyethylene/adhesive layer/nylon 6 was obtained by blow molding a three-layer in-die laminate. In addition, as a comparative example, 99.5 parts by weight of unmodified high-density polyethylene (MI 0.3, specific gravity 0.95) and 0.5 parts by weight of linear polyester (Vylon 200) were melt-kneaded and pelletized (Comparative Example 3) or 10 parts by weight of the above modified polymer. Three-layer in-die lamination extrusion blow molding was performed in the same manner using 90 parts by weight of 100% and unmodified high-density polyethylene (MI 0.3, specific gravity 0.95), which were melt-kneaded and pelletized (Comparative Example 4), as adhesives. A laminated hollow container was obtained (the average wall thickness of the body of the container was 0.4 mm/50μ/50μ). Test pieces with a width of 15 mm were prepared from these containers, and the interlayer peel strength between the adhesive layer and nylon 6 was measured, and the following results were obtained. Example 6 1.5Kg/15mm Comparative example 3 0Kg/15mm Comparative example 4 0.5Kg/15mm Example 7 Comparative examples 5 and 6 Low density polyethylene modified with acrylic acid (MI3.7, specific gravity 0.92, acrylic acid content 1.2wt) %)
A mixture of 50 parts by weight, 49 parts by weight of unmodified low-density polyethylene (MI4, specific gravity 0.92), and 1 part by weight of linear polyester (Vylon 200) was prepared with a diameter of 40 mm and L/D.
The mixture was extruded into strands using a No. 28 extruder, cooled with water, and then cut into pellets. Using this pellet as an adhesive, a three-layer dylaminic film (thickness 70μ/10μ/10μ) of low density polyethylene/adhesive layer/nylon 6 was molded. In addition, as a comparative example, a mixture of 99 parts by weight of low density polyethylene (MI4, specific gravity 0.92) not containing the above modified polymer and 1 part by weight of linear polyester (Vylon 200) (Comparative Example 5) or 50 parts by weight of the above modified polymer and no Mixture of 50 parts by weight of modified low density polyethylene (MI4, specific gravity 0.92) (Comparative Example 6)
A three-layer dilaminar film was similarly molded using each of these. The interlayer peel strength between the adhesive layer and nylon 6 of these laminated films was as follows. Example 7 0.6Kg/15mm Comparative Example 6 0Kg/15mm Comparative Example 7 0.1Kg/15mm Example 8 High-density polyethylene (modified HD/PE; MI 0.4, specific gravity 0.95) with maleic anhydride addition rate of 0.35% by weight Terephthalate (Arnite A200 manufactured by AKZO) was mixed in the proportions shown in the table below, melted and kneaded at 200°C using an extruder with a diameter of 40 mm and L/D of 28, extruded into a strand, cooled with water, and then cut. Got pellets. Using these pellets as an adhesive, a three-layer laminate film of unmodified high-density polyethylene (MI 0.8, specific gravity 0.95) and nylon 6 was formed by in-die lamination molding (thickness 65μ/10μ/10μ). . The delamination strength of these laminated films is shown in the following table.

[Table] Example 9 A high-density polyethylene/adhesive layer was prepared in the same manner as in Example 8, except that nylon 6 in the adhesive layer was replaced with a saponified ethylene-vinyl acetate copolymer (saponified EVA; EVAL). / A three-layer laminated film (thickness 80μ/10μ/10μ) of saponified EVA was molded. The delamination strength of these laminated films is shown in the following table.

【table】

Claims (1)

[Claims] 1 When laminating a polyolefin (A) and a resin (B) selected from polyamide and a saponified product of ethylene-vinyl acetate copolymer, an unsaturated carboxylic acid or its anhydride is used as an adhesive between the two layers. thing
Modified polyolefin containing 0.01-10% by weight
0.5~99.5 parts by weight and thermoplastic polyester 99.5~
1. A method for producing a laminate, characterized in that the laminate is melt-bonded using a composition containing 0.5 parts by weight.