JPS6016895B2 - Method for separating and recovering each layer of a coextruded multilayer laminate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for separating and recovering each layer of a coextruded multilayer laminate comprising a polyolefin resin and a polar resin.

In recent years, multilayer films and multilayer laminated hollow containers manufactured by coextruding polyolefin resins and polar resins such as polyamide resins and ethylene-vinyl alcohol copolymers have been used in food packaging and other fields.

In such a laminate, in order to prevent delamination during practical use, for example, a modified resin to which an unsaturated carboxylic acid is grafted as a polyolefin resin to give adhesiveness is used, and the interlayer adhesion between the polyolefin resin and the polar resin is improved during coextrusion. It strengthens the On the other hand, in the molding of plastics, scraps such as defective products, burrs, trimming losses, etc., are always generated during the manufacturing process, so techniques for collecting and recycling such scraps are required from an economic point of view. In order to collect and reuse scraps of laminates, the laminate must be separated into each layer and then collected. making mechanical separation increasingly difficult.
As a result of intensive studies under such circumstances, the present inventors found that by using a polyolefin resin with a specific composition and treating it under specific conditions, each layer of a coextruded multilayer laminate can be easily separated and recovered in a high yield. We have found a way.

That is, the present invention provides a method for separating and collecting each layer of an extruded multilayer laminate of a polyolefin resin and a polar resin having an adjacent laminate structure of an adhesive polyolefin resin and a gutter resin, in which a bale separation adjacent to a polar resin layer is used. As a polyolefin resin, the following formula {i}Y>X-15q○
...[A] [However, Y is the crystallization temperature (00) of the adhesive polyolefin resin, X is the Vigat softening point], and the temperature near the lamination interface of the coextruded laminate is equal to the residual heat during manufacturing. A coextruded multi-layer laminate consisting of a polyolefin resin and a polar resin, characterized in that the resin is pulverized into small pieces at a temperature of (x-15°C) or higher, and then the resin of each layer is separated and recovered. This is a method of separating and collecting materials into each layer.

The multilayer laminates targeted by the present invention include, for example, a two-layer structure of adhesive polyolefin resin/polar resin, polyolefin resin/adhesive polyolefin resin/polar resin, adhesive polyolefin resin/polar resin/adhesive polyolefin resin, and gutter structure. Resin/adhesive polyolefin resin/polar resin 3
The layered structure includes at least a laminate structure of adhesive polyolefin resin/polar resin, such as a four-layer structure of polyolefin resin/adhesive polyolefin resin/gutter resin/adhesive polyolefin resin.

The gutter resin referred to in the method of the present invention is a polymer having extrusion moldability and crystallinity, such as nylon 6, nylon 66, nylon IQ, nylon 11, nylon 12.
Polyamides such as polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polyesters such as polyethylene terephthalate noisophthalate, ethylene with an ethylene content of 50 mol% or less
Examples include pinyl alcohol copolymers, polycarbonates, and polyacetals.

The polyolefin resin in the present invention is a homopolymer of Q-olefin such as ethylene, propylene, 1-butene, 1-pentene, or 2 of the above-mentioned Q-olefins.
A polymer consisting of the above-mentioned Q-olefin as a main component, and other vinyl monomers other than Q-olefin, such as conjugated diene such as butadiene and isobrene, and fatty acids such as vinyl acetate and vinyl propionate. These include unsaturated carboxylic acids such as vinyl, acrylic acid, and methacrylic acid, derivatives thereof, and copolymers thereof, and the concept also includes adhesive polyolefin resins in the present invention.

The polyolefin resin of the present invention has heat resistance stability, weather resistance stabilizer, antistatic agent, slip agent, antiblocking agent,
It may also contain flame retardants, pigments, dyes, fillers, reinforcing agents, softeners, rubbery polymers, and the like. The adhesive polyolefin resin in the present invention is a polyolefin resin that has thermal adhesion properties to a magnetic material, and is mainly composed of Q-olefins such as ethylene, propylene, and 1-butene, and is composed of Q-olefins such as ethylene, propylene, 1-butene, etc. A composition of a polymer or a copolymer thereof and an unmodified polyolefin, a modified polyolefin obtained by grafting a gutter vinyl monomer onto an unmodified polyolefin resin, or a composition of such a modified polyolefin and an unmodified polyolefin. It is a thing.

Examples of the above-mentioned polar vinyl monomers in the present invention include vinyl monomers having epoxy groups, such as glycidyl acrylate and glycidyl methacrylate, unsaturated carboxylic acids or derivatives thereof, such as acrylic acid, methacrylic acid, maleic acid, and fumaric acid. Examples include acids, itaconic acid, and their acid anhydrides, esters, amides, imides, metal salts, and the like.

In addition, the unmodified polyolefin referred to in the method of the present invention is, for example, a homopolymer of Q-olefin such as ethylene, propylene, 1-butene, 1-bentene, 3-methyl-1-butene, 1-hexene, 4-methyl-1-bentene, or the above-mentioned Q-olefin. A crystalline polymer having a definite melting point and crystallization temperature, such as a block or random copolymer of two or more types of Q-olefins, or a copolymer of the above Q-olefin and a cogen such as butadiene or isoprene.

In addition, the adhesive polyolefin resin in the present invention includes a rubber-like polymer in a range in which the adhesive polyolefin resin can form a matrix, for example, up to 6% by weight, preferably up to 5% by weight, based on the entire composition. For example, ethylene propylene rubber, ethylene propylene diene rubber, polyisoptylene, polyptadiene, etc. may be included. The first feature of the present invention is that the adhesive polyolefin resin has the following formula:
...{i} [However, Y is the crystallization temperature (00) of the adhesive polyolefin resin, and X is the Vigat softening point (0
0)] was selected.

In addition, the Vigatto softening point in the present invention is defined as ASTM-D
-1525.

Normally, the Vigat softening point of high-density polyethylene is 120 to 1.
30:00, and that of high-pressure low-density polyethylene is 9
0-100℃, polypropylene 140-155q0,
An ethylene/vinyl acetate copolymer containing 14% by weight of vinyl acetate has an amount of 65 to 70q0. The crystallization temperature in the present invention is the temperature at the position of the exothermic peak due to crystallization measured by DSC (differential scanning calorimeter) at a rate of 5° C./min. In the case where the polyolefin resin is composed of a composition of two or more resins, and two or more exothermic peaks due to crystallization appear, first, the crystallization temperature of the resin forming the matrix is adjusted to When there are multiple resins, the crystallization temperature of the resin with a higher crystallization temperature is taken as the crystallization temperature of the composition. Usually, the crystallization temperature of high density polyethylene is 100 to 115°C, and that of polypropylene is 105 to 120 qo. From the above, the crystallization temperature of ordinary ethylene homopolymers and propylene homopolymers (Vigat softening point - 15°C) is higher than or almost the same as that of the crystallization temperature, so in the present invention, these polymers are used individually. Those skilled in the art will readily understand that this is difficult to use as an adhesive polyolefin resin.

In other words, the adhesive polyolefin resin that can be used in the present invention includes, for example, a composition of a resin having a high crystallization temperature and a resin having a low crystallization temperature, for example, a composition with a high crystallization temperature such as polypropylene or high density polyethylene. Low-density polyethylene, ethylene, propylene copolymer, ethylene/1-butene copolymer, ethylene/vinyl acetate copolymer, ethylene/acrylic acid ester copolymer, ethylene/methacrylic acid, etc. Compositions with resins having a low crystallization temperature such as partial metal salts of copolymers, [b- Compositions of crystalline polyolefins and rubbery polymers, such as crystalline polyethylene, polypropylene, poly-1-butene, etc.] Polyolefin and ethylene
Compositions with rubber-like polymers such as propylene rubber, polyisobutylene, or partially crosslinked products thereof, 'c} Block copolymers having a chain portion with a high crystallization temperature and a chain portion with a low crystallization temperature, such as propylene・Ethylene block copolymer, propylene/ethylene/propylene block copolymer, ethylene/ethylene nop.

These include pyrene block copolymers. Of course, in the above composition or copolymer, at least a part of the polyolefin resin component is composed of a modified polyolefin containing a magnetic vinyl monomer, as described above. To explain in more detail the adhesive polyolefin composition that can be used in the present invention, taking high-density polyethylene as an example, the crystallization temperature of high-density polyethylene including modified high-density polyethylene is 100 to 115 qo (Vigat softening point - 1 yo). is about 2 to 7°C higher than that.

On the other hand, a composition containing modified high-density polyethylene with a ratio of high-density polyethylene: ethylene/propylene rubber = 80:20 (Vigat softening point -15 qo) is 90 to 100°C, and a composition with a ratio of 70:30 has a softening point of 85 to 95 q0. Become,
At 50:50, it becomes 45-55 times zero. Therefore, in order to increase the temperature difference between the crystallization temperature and (Vigat softening point -15oo), it is sufficient to increase the low Vigat softening point component, but this results in poor heat-resistant adhesion when using a laminate. Therefore, its amount is limited. In order to carry out the method of the present invention, the adhesive polyolefin composition (Pigat softening point -15 qo) is heated to a temperature of 50° C. or more and below the crystallization temperature of the composition, preferably 10 qo or less below the crystallization temperature. It is preferable to select the composition ratio so that In the case of a composition ratio consisting of high-density polyethylene containing modified high-density polyethylene and ethylene propylene rubber, the high-density polyethylene containing modified high-density polyethylene is 95 to 4% by weight, preferably 90% by weight, based on the entire composition.
5 to 5% by weight, especially 80 to 6% by weight, and 5 to 60% by weight of ethylene propylene rubber, preferably 10 to 5% by weight, especially 20 to 4% by weight. It is preferable to select. The above-mentioned multilayer laminate structure consisting of a polyolefin resin layer and a polar resin layer is usually produced by melting the polyolefin resin and the polar resin in separate extruders, and then melting the polyolefin resin and polar resin in a predetermined manner by using a single die with flow channels merging at the tip. Extruded in layers to shape.

The resin temperature at the time of melting is usually the resin's (crystal melting temperature 110
℃) to 300oo, preferably (crystal melting temperature +2
0° C.) to 270° C., and the temperatures of both resin layers are often made equal. The present invention provides a particularly useful method for disposing of scraps such as rejects, burrs, and trimming losses generated during the production of such laminated structures. After that, the area near the interface between the adhesive polyolefin resin layer and the polar resin layer is still at a temperature of 15°C or more below the Vigat softening point of the adhesive polyolefin resin due to residual heat during manufacturing, preferably in an atmosphere lower than that of the scrap. The point is that the polyolefin resin layer and the polar resin layer can be easily separated by crushing the laminate.

That is, as a result of the present inventors' investigation of the relationship between the interfacial temperature and interlayer adhesion of a multilayer laminate consisting of an adhesive polyolefin resin layer and a polar resin layer obtained by coextrusion, the interlayer adhesion between both layers was determined. changes significantly at a temperature of 15q0 below the Vigat softening point of the adhesive polyolefin resin, is extremely weak above this temperature, and tends to increase rapidly as the temperature drops below this temperature. The adhesive polyolefin resin layer can be formed by grinding at a temperature near the adhesive interface of the adhesive polyolefin resin (Vigat softening point -15oo) or higher, preferably at a temperature higher than the Vigat softening point -1oo○, particularly preferably at a temperature higher than the Vigat Europeanization point. It was discovered that scales can be easily peeled off from the polar resin layer. The temperature near the interface between the adhesive polyolefin resin layer and the polar resin layer during pulverization must also be below the crystallization temperature of either resin. If the temperature near the interface is above the crystallization temperature of either or both resins, or if either or both resins are molten, the molten resin layer will stick to the other resin. It is crushed in a state in which it is crushed, making it difficult to separate the two notifications. However, in the method of the present invention, residual heat is used when the laminate is manufactured by coextrusion, and if the pulverization process is performed in an atmosphere with a temperature lower than that of the resin material of the laminate, there will be no residual heat during the pulverization. The temperature of the laminate can easily be below the crystallization temperature. In the method of the invention, the multilayer laminate obtained by coextrusion is ground.
The laminate can be crushed using a crushing device such as a hammer mill, cutter mill, pulverizer, double roll crusher, or roller mill, which crushes the object by using forces such as impact, cutting, friction, or a combination of these. can be done. By pulverizing when the temperature near the interface between the adhesive polyolefin layer and the polar resin layer is within the above temperature range, the polyolefin layer and the polar resin layer are separated into pieces, and the generated pieces are made of polyolefin. The result is a mixture of strips of resin and strips of polar resin.

Methods for separating each resin piece from a mixture of these pieces include, for example, a specific gravity separation method that uses the difference in specific gravity between a polar resin and a polyolefin resin, an electrostatic separation method that uses electrical properties, and a method that uses the thickness of each layer. Examples include the differences in power and the wind separation method used.

The separated and recovered polar resin and polyolefin resin can be re-granulated and reused as they are or by mixing unused resin.

According to the method of the present invention, the separation and recovery rate of the laminate is excellent as shown in the examples below, and only a device that combines a normal thermoplastic resin scrap processing device and a separation device is required. , economical. EXAMPLES Next, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples unless the gist thereof is exceeded.

Example 1 High density polyethylene (melt index)
190oo)0.03) was melted at 23000 and fed to a die for a three-layer laminated sheet.

On the other hand, high-density polyethylene (melt index 14)
to which 2% by weight of maleic anhydride was added (hereinafter referred to as modified P)
E) 10 parts by weight, high density polyethylene (melt index 0.3 hereinafter abbreviated as HDPE) 6 parts by weight,
and 30 parts by weight of ethylene propylene rubber (ethylene content: 80 mol.0, melt index: 1.2, hereinafter abbreviated as EPR) 105q
0) was melted to 230 qo in another extruder and fed to the die.

Furthermore, nylon (manufactured by Toray Industries, Amiran CMIO II) was added as a third layer.
It was melted in the same extruder and applied to the same die. The die has multiple manifolds corresponding to separate extruders;
After leaving the manifold, the resins collide in front of the lip. The inside of the die is 15% yield, the lip is 5~
It is adjusted to 6 ribs. As a result, HDPE layer 5 willow, adhesive polyethylene composition layer 0.1 skin, nylon layer 0.2
Table 1 shows the results of measuring the temperature dependence of the peel strength between the nylon layer and the polyethylene layer of this multilayer skin sheet. Immediately after coextruding from the die in the same manner as described above, the multilayer sheet is cut to a certain length, placed in a paper container, and the temperature T indicated by a resin thermometer inserted near the adhesive polyethylene layer is measured. When it reached a predetermined value, the multilayer sheet was put into a 2k9 rotary blade crusher (manufactured by Rorai Tekko Co., Ltd.) and crushed into small pieces with an average particle size of about 4 grains. Next, the pulverized products obtained by the above method were visually inspected to determine whether the pieces a were made of nylon only, the pieces b were made of HDPE and an adhesive polyethylene composition, and the pieces were made of nylon/adhesive polyethylene/HD.
After manually dividing the PE laminate into strips c, measure the weight of each piece and use the formula: [[a'ten'b-]/['a}+'b'ten'
d] × 100: The separation rate (P) was determined by P. The temperature near the interface of the laminated sheet obtained by the above method (TO
Table 2 shows the relationship between the separation rate (P) and the separation rate (P) by pulverization.
Example 2 Parts by weight of HDPE7 as adhesive polyethylene composition,
Example 1 was carried out in the same manner as in Example 1, except that a composition (crystallization temperature of the composition: 106° C., Vigat softening point: 11) consisting of parts by weight of EPR2 and 1 part by weight of modified PEI was used.

The results are shown in Tables 1 and 2. Example 3 An adhesive polyethylene composition consisting of 40 parts by weight of HDPE, parts by weight of EPR5, and parts by weight of modified PEI (crystallization temperature of the composition: 105° C., Vigatto softening point: 65 qo)
The same procedure as in Example 1 was carried out except that .

The results are shown in Tables 1 and 2. Table 1 Table 2 Comparative Example 1 Other than using a composition consisting of 90 parts by weight of HDPE and parts by weight of modified PEIO (crystallization temperature of the composition: 10°C, Vigat softening point: 126°C) as a post-adhesive polyethylene composition. The test was carried out on the same aircraft as in Example 1.

Claims (1)

[Scope of Claims] 1. In a method of separating and recovering each layer of a coextruded multilayer laminate of a polyolefin resin and a polar resin having an adjacent laminate structure of an adhesive polyolefin resin and a polar resin, The adhesive polyolefin resin is expressed by the following formula (a) Y>X-15℃...(a) [However, Y is the crystallization temperature of the adhesive polyolefin resin (
Using a resin that satisfies the Vikatsu softening point (℃), A method for separating and recovering a coextruded multilayer laminate consisting of a polyolefin resin and a polar resin into each layer, which comprises pulverizing and cutting into pieces, and then separating and recovering each layer by resin. 2. The method according to claim 1, wherein the coextruded multilayer laminate is a laminate consisting of three layers: polyolefin resin/adhesive polyolefin resin/polar resin. 3. The method according to claim 2, wherein the polyolefin resin is high-density polyethylene. 4
3. The method according to claim 2, wherein the adhesive polyolefin resin is a composition comprising polyethylene partially or wholly graft-modified with an unsaturated carboxylic acid or a derivative thereof and a rubber-like polymer. 5. The method according to claim 1, wherein the pulverization is carried out at an ambient temperature lower than the temperature near the lamination interface of the coextruded laminate.