JPH0318831B2 - - Google Patents

Description

[Detailed description of the invention]

This invention provides a laminated layer that has excellent heat sealability, heat resistance, water resistance, water vapor resistance, and blocking resistance, and also has excellent adhesion to polypropylene molded products whose heat sealability does not deteriorate over time even in various atmospheres. It is about things. Traditionally, ``press-through packs'' for pharmaceuticals, ``blister packs'' for solid or pasty foods such as yam, butter, curry roux, and chiyocolate, and paper or paper containing ramen noodles, shiruko, fermented milk, lactic acid bacteria drinks, etc. Aluminum foil-based laminates are often used for packaging plastic cups and the like. In particular, containers made of polypropylene or a laminate of polypropylene and aluminum foil, with a polypropylene film attached, are often used as lids; in this case, polypropylene is more transparent than vinyl chloride or polystyrene. Although it is superior in terms of humidity and heat resistance, in order to fuse polypropylene together,
It is necessary to increase the sealing temperature, which is not economical, and there are other drawbacks, such as the fact that it is difficult to open the lid part by hand when taking out the contents. In addition to the lid material, a laminate of plastic, such as homopolymer or copolymer film such as polypropylene or polyethylene, and aluminum foil is often used, which is formed into the shape of a bag or container. In this case, a two-component reactive urethane adhesive is usually used to laminate aluminum foil and plastic film, but this type of adhesive requires strict aging during the aging process to ensure proper curing reaction. Temperature and time control are required, and workability is extremely poor. Furthermore, the initial adhesive strength is not strong, and the bonded surfaces of the plastic films must be treated by corona discharge or the like. Furthermore, aluminum foil is coated with an anchor coating agent and low-density polyethylene is extruded and laminated on top of the aluminum foil, which is used in the form of a bag. Because there is no good anchor coating agent, the desired laminate cannot be obtained. Therefore, polypropylene resin has heat resistance,
While having excellent properties such as chemical resistance and moisture resistance,
Due to the lack of suitable heat sealants, adhesives or anchor coatings, desirable laminates of aluminum foil-based polypropylene resins have not been available for various applications. The present invention was made to eliminate such drawbacks, and it is possible to use a film such as aluminum foil or polyethylene terephthalate for a molded product made of polypropylene, or a molded product made of a laminate or composite material whose heat-sealed surface is polypropylene. When bonding polypropylene film and plastic film substrates such as aluminum foil or polyethylene terephthalate by thermal bonding, and when extruding polypropylene onto plastic film substrates such as aluminum foil or polyethylene terephthalate. The object of the present invention is to provide a laminate that has excellent adhesion to a polypropylene molded product, which is coated with a resin composition that is sometimes preferred on the base material surface. The details of this invention will be explained below. Although chlorinated polypropylene is known to adhere well to polypropylene and is used for printing or coating polypropylene films, it does not adhere at all to aluminum foil and polyethylene terephthalate film. Therefore, in order to impart adhesion to aluminum foil or polyethylene terephthalate without reducing the adhesion to polypropylene, it is necessary to introduce a certain amount of carboxyl groups into chlorinated polypropylene. Chlorinated carboxylated polypropylene resin is
A chlorinated carboxylated polypropylene resin with an acid value of 0.1 to 100 mgKOH/g, and a chlorine content of 5 to 50% by weight. Here, the polypropylene that is the raw material for the chlorinated carboxylated polypropylene resin may be either a homopolymer or an ethylene-propylene copolymer,
First, carboxyl groups are introduced into polypropylene by a known method so that the acid value becomes 0.1 to 100 mgKOH/g. This is obtained, for example, by copolymerizing polypropylene with an α,β-unsaturated carboxylic acid or an anhydride thereof alone or in combination. Here, the α,β-unsaturated carboxylic acid or its anhydride includes acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, maleic anhydride, itaconic anhydride, and methyl and ethyl maleic acid or fumaric acid. Examples include hydrogen esters. The acid value is preferably 0.1 to 100 mgKOH/g.
If the acid value exceeds this range, the adhesion between the polymer and metal will improve, but the adhesion to polypropylene will be poor; on the other hand, if the acid value is lower than the above range, the adhesion to metal will become poor. So I don't like it. Note that when carboxylated polypropylene resin is chlorinated, as mentioned above, the chlorine content should be 5 to 50% by weight; however, if it is less than 5%, it will have poor solubility in organic solvents. This is because a uniform coating film cannot be obtained and the solution stability is also poor. On the other hand, if it exceeds 50%, the adhesiveness to polypropylene decreases and the heat seal strength decreases. Furthermore, in order to increase the adhesion to polyethylene terephthalate without reducing the adhesion to polypropylene, it is preferable to blend a linear copolymerized polyester resin with the chlorinated carboxylated polypropylene resin. In this way, a solution with a higher solids content and lower viscosity than when using chlorinated carboxylated polypropylene resin alone can be obtained, and workability during application is significantly improved, and a uniform coating film can be obtained. It becomes easier to obtain. Here, in the linear copolymerized polyester resin, 95 to 50 mol% of the acid component is terephthalic acid residue, 20 to 70 mol% of the alcohol component is ethylene glycol residue, and the resin is soluble in organic solvents. It is.
The remaining 5 to 50 mol% of the acid component consists of residues of aromatic dibasic acids such as adipic acid, sebacic acid, other aliphatic dibasic acids, isophthalic acid, orthophthalic acid, and diphenyldicarboxylic acid. The remaining 80 to 30 mol% of the alcohol component is 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,3-butanediol, diethylene glycol, triethylene glycol, dipropylene glycol, Consists of glycol residues such as glycol and neopentyl glycol. Note that a residue of oxyacid such as oxybenzoic acid may be present. In addition to the above-mentioned linear random copolymer polyesters, linear block copolymer polyesters (modified ether type polyesters) are also included in the linear copolymer polyesters of the present invention. That is, modified ether type polyester is produced by using polyethylene terephthalate as a starting material, adding triethylene glycol and other diols to it, and carrying out depolymerization and recondensation reaction by ester conversion reaction with diols. , in which ethylene glycol in polyethylene terephthalate is partially replaced with diol. In this invention, the chlorinated carboxylated polypropylene resin can be used in an amount of 10 to 99 parts by weight, comprehensively considering the mutual compatibility of the various resins described above and the adhesion to substrates such as aluminum foil and polyethylene terephthalate film, as well as to polypropylene. It is preferable to mix 90 to 1 part by weight of the linear copolymerized polyester resin. This is because when the amount of chlorinated carboxylated polypropylene resin exceeds 99 parts by weight, the adhesion to aluminum foil and polypropylene is excellent, but the adhesion to polyethylene terephthalate is poor; This is because if it is less than that, the adhesion to aluminum foil and polypropylene will deteriorate. For the above composition, in order to further improve the adhesive properties, ethylene-vinyl acetate copolymer, vinyl chloride-vinyl acetate copolymer, acrylic ester, chlorinated polyethylene, epoxy resin, petroleum resin, synthetic rubber , natural rubber, etc., may be added as a third component. At this time, the amount of these resins etc. is approximately 50% based on the total amount of the composition.
It is preferably at most 40% by weight (however, the composition ratio of the main components of the present invention is as described above), particularly at most 40% by weight. If too much of these third components is added, the mutual compatibility between the resins will deteriorate, the coating will become brittle, and the adhesive strength will decrease. In addition to these resins,
If necessary, an antiblocking agent, an antistatic agent, a lubricant, etc. may be further added. In this invention, the polypropylene to be heat-sealed and bonded and the extruded polypropylene resin are propylene homopolymer,
A modified polypropylene resin modified with a propylene-ethylene copolymer and an unsaturated carboxylic acid or its anhydride, methyl ethyl ketone (MEK ), applied in the form of a solution dissolved in an organic solvent such as toluene or xylene, or in the form of an emulsion, or applied in the form of a heated melt. As a coating method, common methods such as a roll coating method, a gravure roll coating method, and an extrusion coating method are used, and as a drying method, a method using hot air, an infrared lamp, or a drum, etc., alone or in combination, is used. Use.
The thickness of the resin layer formed by coating is preferably about 20 μm or less after drying. Examples and comparative examples are shown below. Examples 1 to 11 The acid component consists of 70 mol% of terephthalic acid residue and 30 mol% of isophthalic acid residue, and the alcohol component consists of 50 mol% of ethylene glycol residue and 50 mol% of neopentyl glycol residue. With a linear copolymerized polyester resin and an acid value of 1 mgKOH/g,
Polypropylene resin with melt index 9 was chlorinated to a chlorine content of 26% and chlorinated carboxylated polypropylene resin was dissolved in a MEK:toluene = 2:8 solvent at the blending ratio shown in Table 1 to a concentration of 20%. %. This was coated on 20μ hard aluminum foil using a 65 mesh gravure roll and dried at 170°C for 15 seconds to obtain a laminate with a 4μ thick heat sealing agent layer. The above aluminum foil was placed on a polypropylene sheet (0.25mm thick) at 180℃ x 3Kg/cm ² x 1 second.

[Table] Heat seal, cut into 15mm width, and peel off speed.
It was peeled off at 100 mm/min and the strength at that time was measured. Similarly, the heat seal strength with polyethylene terephthalate film was also measured. Also, heat-sealed under the above conditions at 40℃,
The heat seal strength was measured after being immersed at 40°C x 90% and in water for one month. Furthermore, the heat-sealed product was retort sterilized at 125° C. for 5 minutes, and the heat-seal strength was measured after the retort was completed. As a blocking resistance test, dozens of sheets of foil coated with heat sealant were stacked up to 1 kg/kg.
A load of cm ² was applied and the sample was left in an atmosphere at 40°C for 48 hours, and then taken out to see if the heat sealant-coated surface was stuck to the aluminum foil. The results are shown in Table 1. Comparative Examples 1-3 Only the blending ratio of the resin was as shown in Table 1, and the other conditions were the same as in Examples 1-11. The results are shown in Table 1. Examples 12-22 The acid component consists of 70 mol% of terephthalic acid residue and 30 mol% of sebacic acid residue, and the alcohol component is
Chlorinated linear copolymerized polyester resin consisting of 50 mol% ethylene glycol residue and 50 mol% diethylene glycol residue, and polypropylene resin with a melt index of 12 at an acid value of 10 mgKOH/g to a chlorine content of 26%. A 50μ soft aluminum foil was coated with carboxylated polypropylene resin in the proportions shown in Table 2 in the same manner as in Example 1. Thereafter, a 20 μm polyester film or a 50 μm polypropylene film and this aluminum foil were stacked and bonded by thermocompression by passing between heated rolls at 160° C. Then, the adhesion height, the adhesion strength at 40°C, 40°C x 90%, the adhesion strength after being immersed in water for one month, and the adhesion strength after retort sterilization at 125°C for 5 minutes were measured. The results are shown in Table 2. Comparative Examples 4 to 6 Only the resin formulation is as shown in Table 2, and the others are as shown in Example 12.
~22 was carried out in the same manner. The results are shown in Table 2.

[Table] Examples 23 to 33 Modified ether type polyester resin obtained by reacting 50 parts by weight of triethylene glycol with 100 parts by weight of polyethylene terephthalate, with an acid value of 20 mgKOH/g and a melt index of 20.
A chlorinated carboxylated polypropylene resin obtained by chlorinating the carboxylated polypropylene resin to a chlorine content of 35% was coated on a 25μ polyethylene terephthalate film in the same manner as in Example 1 at the blending ratio shown in Table 3. Heat-sealing properties, changes over time, and blocking resistance were tested in the same manner as in Example 1. Easy openability was determined by heat-sealing the lid to a polypropylene container and peeling off the lid by hand, based on the ease of peeling, adhesive strength, wrinkles in the lid, etc. The results are shown in Table 3. Comparative Examples 7 to 9 Only the resin formulations are as shown in Table 3, and the other examples are as shown in Table 3.
It was done in the same way as steps 23-33. The results are shown in Table 3.

【table】

[Table] Example 34 80 parts by weight of a chlorinated carboxylated polypropylene resin obtained by chlorinating a modified polypropylene resin with an acid value of 1 mgKOH/g and a melt index of 9 to a chlorine content of 26% by weight, and an acid component containing 70% of terephthalic acid residue.
mol% and 30 mol% of sebacic acid residues, and 20 parts by weight of a linear copolymerized polyester resin whose alcohol component consists of 50 mol% of ethylene glycol residues and 50 mol% of diethylene glycol residues were fitted and dissolved in toluene. , the concentration was 10%. This solution
Coat on 50μ aluminum foil using a 130 mesh gravure roll, dry at 120℃ for 15 seconds, and coat with 1.2μ aluminum foil.
A laminate with a thick anchor coat layer was obtained. This aluminum foil was coated with a polypropylene resin having a melt index of 21 by extrusion through a T-die at a molten resin temperature of 270°C. In addition, carboxylated polypropylene resin with a melt index of 9 and an acid value of 1 mgKOH/g was prepared at a melt temperature of 290°C.

[Table] * Extrusion coating with cut film. The film thickness was 30μ in each case. Adhesion evaluation is T peeling, peeling speed
It was carried out at 100mm/min. The results are shown in Table 4. Comparative Example 10 The same procedure as in Example 34 was carried out using a chlorinated polypropylene resin obtained by chlorinating a polypropylene resin with a melt index of 22 to a chlorine content of 20% by weight. The results are shown in Table 4.

Claims (1)

[Claims] 1 10 to 99 parts by weight of a chlorinated carboxylated polypropylene resin obtained by chlorinating a carboxyl group-containing modified polypropylene resin with an acid value of 0.1 to 100 mgKOH/g to have a chlorine content of 5 to 50% by weight, and a linear copolymerized polyester resin A laminate having excellent adhesion to a polypropylene molded product, characterized in that a resin composition prepared by mixing 90 to 1 part by weight of polypropylene is coated on a base material surface.