JPS612555A - Packaging material for polypropylene molded shape - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention This invention is for polypropylene molded products that have excellent heat sealability, heat resistance, water resistance, water vapor resistance, and blocking resistance, and whose heat sealability does not deteriorate over time even in various atmospheres. It concerns packaging materials.

Conventionally, we have used ``press-through packs'' for pharmaceuticals, blister packs for solid or pasty foods such as dairy products, butter, curry roux, and chocolate, as well as ramen noodles, shiruko, fermentation holes, lactic acid bacteria drinks, etc. Aluminum foil-based laminates are often used for wrapping paper or plastic cups. In particular, containers made of polypropylene or a laminate of polypropylene and aluminum foil with a polypropylene film attached are often used as lids. Although it is excellent in terms of humidity and heat resistance, it is necessary to increase the sealing temperature to fuse the polypropylene together, which is not economical, and when taking out the contents,
There are drawbacks such as difficulty in opening the lid part by hand.

In addition to the lid material, a laminate of a homopolymer or copolymer film of plastic, 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. Moreover, the initial adhesive strength is not strong, and the bonded surfaces of the plastic films must be treated by corona discharge or the like.

In addition, aluminum foil is coated with an anchor coating agent and low-density polyethylene is extruded and laminated on top of this, or it is used in the form of a bag, but even if you try to use polypropylene instead of low-density polyethylene, the adhesive Because there is no good anchor coating agent, the desired laminate cannot be obtained.

Therefore, although polypropylene resin has excellent properties such as heat resistance, chemical resistance, and moisture resistance, there is no suitable heat sealing agent, adhesive, or anchor coating agent.
It has not been possible to obtain desirable laminates of polypropylene resin based on aluminum foil for various applications.

This invention was made to eliminate such drawbacks.
When thermally bonding a film-like base material such as aluminum foil or polyethylene terephthalate to a polypropylene molded product or a molded product made of a laminate or composite material whose heat-sealed surface is polypropylene, the polypropylene film and aluminum foil or A resin composition suitable for bonding plastic film-like substrates such as polyethylene terephthalate by thermal adhesion and extruding polypropylene onto aluminum foil or plastic film-like substrates such as polyethylene terephthalate is applied to the substrate surface. The present invention provides packaging materials for polypropylene molded products.

The details of this invention will be explained below.

It is known that chlorinated polypropylene adheres well to polypropylene and is used for printing or coating polypropylene films, or it does not adhere at all to aluminum foil and polyethylene terephthalate films. 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 has an acid value of 0.
．． 1~100~KOH/j7 carboxylated polypropylene resin is chlorinated, and the chlorine content is 5~
It is 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. 7
Ethyl J1. Introducing a unicarboxyl group. 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 reason why an acid value of 0.1 to 100 to xcOH/f7 is desirable is that if it exceeds this range, the adhesive strength between the polymer and metal will improve, but the adhesive strength to polypropylene will become inferior; If the acid value is lower than the above range, the adhesion to metal will be poor, which is not preferable.

In addition, when chlorinating carboxylated polypropylene resin, as mentioned above, the chlorine content is 5 to 50% by weight.
However, if the width is less than 5, the solubility in organic solvents becomes poor and a uniform coating film cannot be obtained.
This is also because the solution stability is also poor, and on the other hand, if it exceeds 50%, the adhesiveness to polypropylene decreases and the heat sealing 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. becomes easier to obtain.

Here, the linear copolymerized polyester resin has an acid component of 95
~50 mol% is a terephthalic acid residue, 20~70 mol% of the alcohol component is an ethylene glycol residue, and the resin is soluble in organic solvents. The remaining 5 acid components
50 mol% consists of residues such as adipic acid, sebacic acid, other aliphatic dibasic acids, and aromatic dibasic acids such as isophthalic acid, orthophthalic acid, and diphenyldicarboxylic acid.

The remaining 80 to 30 mol% of the alcohol component is 1
．． It consists of glycol residues such as 2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 113-butanediol, diethylene glycol, triethylene glycol, dipropylene glycol, and neopentyl glycol. Note that there may be a residue of an oxyacid such as oxybenzoic acid.

In addition to the above linear random copolymer polyesters, linear block copolymer polyesters (modified ether type polyesters) are also included in the linear copolymer polyesters of the present invention. In other words, modified ether type polyester is produced by using polyethylene terephthalate as a starting material, adding triethylene glycol and other diols to it, and performing depolymerization and recondensation reactions through ester conversion reactions using the diols. Ethylene glycol in terephthalate is partially replaced with diol.

In this invention, if the mutual compatibility of the various resins described above and the adhesion to substrates such as aluminum foil and polyethylene terephthalate film and polypropylene are comprehensively considered, the weight of the chlorinated and ruboxolated polypropylene resin is 10 to 99%. It is preferable to mix 90 to 1* parts of the linear copolymerized polyester resin per part of the linear copolymerized polyester resin. This is because when the chlorinated carboxylated polypropylene resin exceeds 99 parts by weight, the adhesiveness to aluminum foil and polypropylene is excellent, but the adhesiveness 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. In this case, the content of these resins and the like is preferably about 50% by weight or less (however, the composition ratio of the main components of the present invention is as described above), particularly 40% by weight or less, based on the total amount of the composition. If too much of these third components is added, the mutual compatibility between the resins will deteriorate, the coating film will become brittle, and the adhesive strength will decrease. In addition to these resins, an antiblocking agent, an antistatic agent, a lubricant, etc. may be further added as necessary.

In this invention, the polypropylene and extruded polypropylene resins to be heat-sealed and laminated are propylene homopolymers, propylene-ethylene copolymers, and modified polypropylene resins modified with unsaturated carboxylic acids or their anhydrides. In order to apply the resin composition according to the invention onto a substrate such as aluminum foil or polyethylene terephthalate film, it can be applied in the form of a solution or emulsion dissolved in an organic solvent such as methyl ethyl ketone (MEK), toluene, or xylene, or Or apply it in a heated and molten state. As the coating method, common methods such as roll coating, gravure roll coating, extrusion coating, etc. are used, and
As a drying method, a method using hot air, an infrared lamp, a drum, or the like may be used alone or in combination.

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 consisted of 70 mol% of terephthalic acid residue and 30 mol% of isophthalic acid residue, and the alcohol component consisted of 50 mol% of ethylene glycol residue and 50 mol% of neopentyl glycol residue. and a chlorinated carboxylated polypropylene resin, which is obtained by chlorinating a polypropylene resin with an acid value of 1 to KOH/7 and a melt index of 9 to a chlorine content of 26%, in the blending ratio shown in Table 1. Then, MEK was dissolved in a solvent of toluene-228 to a concentration of 20%.

This was coated onto 20 μ hard aluminum foil using a gravure roll at 65 mesh Celsius and dried at 170×15 seconds to obtain a packaging material with a 4 mm thick heat sealing agent layer.

The above aluminum foil was covered with a polypropylene sheet (0,2
5 thickness) under the conditions of 180 x 3 x 9/d x 1 second at 180 °C, cut into 15 + u + widths, peeled at a peeling speed of 100 g/min, and measured the strength at that time. Similarly, the heat seal strength with polyethylene terephthalate film was also measured.

Also, heat sealed under the above conditions at 40°0°40
Heat seal strength was measured at X90% and after being immersed in water for one month. Further, the heat-treated samples were sterilized by retorting at 125° C. for 5 minutes, and the heat-sealing strength was measured after the retort was completed.

As a blocking resistance test, several dozen sheets of foil coated with a heat sealant were stacked, a load of I Kp/cJ was applied, and the foil was left in an atmosphere of 40 °C for 48 hours.
I took it out and checked to see if the heat sealant coated side was touching the aluminum foil.

The results are shown in Table 1.

"Comparative Examples 1 to 3" Only the resin blending ratio is as shown in Table 1, and the others are as shown in Examples 1 to 1.
The same procedure as 1 was carried out. The results are shown in Table 1.

"Examples 12 to 22" The acid component consists of 70 mol% of terephthalic acid residues and 30 mol% of sebacic acid residues, and the alfur component consists of 50 mol% of ethylene glycol residues and 5 mol% of diethylene glycol residues.
A linear copolymerized polyester resin consisting of 0 mol% and a chlorinated carboxylated polypropylene resin obtained by chlorinating a polypropylene resin with an acid value of 10 η KOH 152 and a melt index of 12 to a chlorine content of 26% at the blending ratio shown in Table 2, A 50" soft aluminum foil was coated in the same manner as in Example 1. Thereafter, a 20μ polyester film or a 50" polypropylene film was layered on the aluminum foil, and the aluminum foil was passed through hot rolls at 160° C. for thermocompression bonding. Then, the adhesive strength was measured at 40° C. 140×90%, the adhesive strength after 1 month immersion in water at 125° C. and the adhesive strength after retort sterilization at 125° C. for 5 minutes. 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 Examples 12 to 22.
I did the same thing. The results are shown in Table 2.

"Examples 23 to 33" l- to 100 parts by weight of polyethylene terephthalate
A modified ether type polyester resin obtained by charging and reacting 50 parts by weight of IJ ethylene glycol with an acid value of 20
■ A chlorinated carboxylated polypropylene resin prepared by chlorinating a carboxylated polypropylene resin with a melt index of 20 using KOH/p to a chlorine content of 35% is mixed into a 25” polyethylene resin in the same manner as in Example 1 at the blending ratio shown in Table 3. It was coated on a terephthalate film. Heat sealability, aging change, and blocking resistance were tested in the same manner as in Example 1.

Easy openability was determined by heat-sealing a polypropylene container as a lid 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 formulation is as shown in Table 3, and the others are as shown in Examples 23 to 3.
The same procedure as in step 3 was carried out. The results are shown in Table 3. Table 3 0180° peeling, V15 gate 0 Peeling speed 100. ,/min.

"Example 34" Chlorinated carboxylated polypropylene resin 80 obtained by chlorinating a modified polypropylene resin with an acid value of 1 my t<oH7y and a melt index of 9 to a chlorine content of 26% by weight
A linear copolymerized polyester consisting of 70 mol% of terephthalic acid residues and 30 mol% of sebacic acid residues as an acid component and 50 mol% of ethylene glycol residues and 50 mol% of diethylene glycol residues as alcohol components. Mix and dissolve 20 parts by weight of resin in toluene to make a concentration of 10%.
And so.

This solution was coated onto 50" aluminum foil using a 130 mesh gravure roll and dried at 120 x 15 seconds to obtain a packaging material with a 1.2" thick anchor coat layer.

A polypropylene resin having a melt index of 21° C. was extruded and coated onto this aluminum foil at a melting resin temperature of 270° C. through a T-die. Also melt index 9
, a carboxylated polypropylene resin with an acid value of 1 KOH/7 was extrusion coated at a melt resin temperature of 290''C.The film thickness was 30μ in each case.Adhesion was evaluated by T-peeling. , peeling speed 100 mm
/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 having a melt index of 22 to a chlorine content of 20% by weight.

The results are shown in Table 4.

Claims (1)

[Claims] A modified polypropylene resin containing a carboxyl group with an acid value of 0.1 to 100 mg KOH/g is chlorinated and linear copolymerized with 10 to 99 parts by weight of a chlorinated carboxylated polypropylene resin with a chlorine content of 5 to 50% by weight. A resin composition formed by mixing 90 to 1 part by weight of a polyester resin, or an ethylene-vinyl acetate copolymer, a vinyl chloride-vinyl acetate copolymer, an acrylic acid ester, a chlorinated polyethylene based on the total amount of this resin composition. , a resin composition containing 50% by weight or less of one or more selected from the group consisting of epoxy resin, petroleum resin, synthetic rubber, and natural rubber is applied on the base material surface. Packaging material for polypropylene molded products.