JPH0246611B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to an adhesive resin composition having good adhesion to both olefin resins (especially propylene resins) and styrene resins. More specifically, (A) at least one propylene selected from the group consisting of a propylene homopolymer, a random copolymer of propylene and ethylene or an α-olefin, and a block copolymer of propylene and ethylene or an α-olefin. (B) a copolymer of ethylene and vinyl acetate, and (C) a block copolymer of a vinyl aromatic compound and a conjugated diene. The object of the present invention is to provide a resin composition that has good adhesion to both type resins and has good adhesion to these molded products (for example, films, sheets, and foams). Conventional technology Synthetic resins, which are widely used as packaging materials, have recently been developed into multilayered structures that combine the properties of individual resins in order to satisfy all of the performance requirements as the uses for packaging products have diversified. Products are being studied and used in the market. Films, sheets, and foams obtained by molding styrene resins have the advantages of relatively low cost, in addition to the good rigidity inherent to styrene resins and molding methods. Currently, it is widely used as various containers such as cups and boxes.
It has the disadvantage of poor heat resistance and oil resistance. On the other hand, as is well known, olefin resins have relatively good oil resistance, and among these olefin resins, high-density polyethylene and propylene resins in particular have better heat resistance than styrene resins. However, there is a problem that it is inferior to styrene resin in terms of rigidity. For these reasons, various multilayer structures of olefin resins and styrene resins have been proposed in order to improve the oil resistance and heat resistance of various molded products made of styrene resins. Originally, olefin resin and styrene resin were
To obtain these multilayer structures, an adhesive layer is essential between them, since their mutual adhesion is very poor. Conventionally, a copolymer of ethylene and vinyl acetate (hereinafter referred to as "EVA") has been used as this adhesive layer, but EVA generally has good adhesive properties with olefin resins (especially ethylene polymers). However, in order to obtain good adhesion with styrenic resins, the vinyl acetate content in EVA must be approximately 35% by weight or more, and such EVA has a strong vinyl acetate odor. It has poor thermal stability, and there are also problems with extrusion stability. In order to improve these problems, for example, butadiene-styrene copolymers (for example, JP-A-49-33973, JP-A-55-126449), styrene-isoprene blocks are used as the adhesive layer of the multilayer structure. Copolymer (JP-A-55-14209), ethylene-
Acrylic acid alkyl ester copolymer (Japanese Unexamined Patent Publication No. 1983)
-85751), graft modified products of unsaturated carboxylic acids of vinyl aromatic compound-conjugated diene compound block copolymers (for example, block copolymers of styrene and butadiene or isoprene) (JP-A-55-87551). ) have been proposed. However, although these adhesive layers exhibit fairly good adhesion with styrene resins, their adhesion with olefin resins (especially propylene resins) is insufficient, especially when the total thickness is 0.2 mm or less,
In addition, when the molding speed of composite is fast, the adhesion with propylene resin and styrene resin is not necessarily satisfactory, and the value of the lower one of adhesion is at most 100 to 130 g/15 mm, which is not practical. It is insufficient in this respect. With this level of adhesion, it is possible to fill various containers molded with multilayer structures obtained using these adhesive layers with, for example, food and subject them to high-temperature heat treatment at a temperature of 100 to 120°C for several minutes. When the adhesive layer peels off,
Function and product value are significantly reduced. A method has also been proposed in which a film coated with an EVA adhesive is bonded to a polypropylene film. However, when this film is heat laminated to a styrene resin sheet or foam, the adhesive strength is approximately 100g/15mm, which is insufficient, and there is not only uneven adhesion, but also poor heat resistance. Furthermore, the cost of the film itself coated with the adhesive is high, which is disadvantageous from an economical point of view. Problems to be Solved by the Invention From the above, the present invention does not have these drawbacks (problems), and is suitable for both styrene resin molded products (e.g. foams and sheets) and propylene resin molded products. Balanced and practical adhesion (at least 150g/15mm, preferably 200g/15mm)
15 mm or more). Means and Effects for Solving the Problems According to the present invention, these problems are solved by: (A) Propylene homopolymers, random copolymers of propylene and ethylene or α-olefins, and propylene and ethylene or - at least one propylene polymer selected from the group consisting of block copolymers with olefins; (B) a vinyl acetate content of 5 to 35% by weight;
and melt flow rate (measured under conditions 4 according to JIS K6730, hereinafter referred to as "MFR")
from a copolymer of ethylene and vinyl acetate (hereinafter referred to as "ethylene-vinyl acetate copolymer"), and (C) a block copolymer of a vinyl aromatic compound and a conjugated diene, in which the The proportion of the propylene polymer in the composition is 1 to 20% by weight, and the proportion of the block copolymer of a vinyl aromatic compound and a conjugated diene is 1 to 25% by weight. %, and the remainder is an ethylene-vinyl acetate copolymer. The present invention will be specifically explained below. (A) Propylene-based polymer The propylene-based polymer used in the present invention includes a propylene homopolymer, a random copolymer of propylene and "ethylene or α-olefin" (hereinafter referred to as "comonomer"), and a random copolymer of propylene and a comonomer. selected from block copolymers of The copolymerization proportion of said comonomers, both in random and block copolymers, is usually at most 20% by weight, especially 15% by weight.
The following are desirable. In addition, the number of carbon atoms in the comonomer is generally at most 12, and typical examples include ethylene, butene-1, hexene-1, and 4-carbon.
Examples include methylpentene-1, with ethylene being particularly preferred. The melt flow rate (measured according to JIS K6758, hereinafter referred to as "MFR") of the propylene polymer is usually 0.01 to 100 g/10
minutes, preferably 0.05 to 80 g/10 minutes, particularly preferably 0.1 to 50 g/10 minutes. If the MFR of the propylene polymer is less than 0.01g/10 minutes,
When producing the composition of the present invention, not only is the kneading property poor, but it is also difficult to obtain a uniform composition, resulting in variations in adhesive properties.
On the other hand, if a propylene-based polymer exceeding 100 g/10 minutes is used, not only the thermal stability of the resulting composition will be poor, but also the extrusion process stability will be poor. (B) Ethylene-vinyl acetate copolymer Also, ethylene-vinyl acetate copolymer used in the present invention
The vinyl acetate content (copolymerization ratio) of the vinyl acetate copolymer is 5 to 35% by weight, preferably 10 to 30% by weight, and particularly preferably 15 to 35% by weight. If the copolymerization ratio of vinyl acetate in the ethylene-vinyl acetate copolymer is less than 5% by weight, the adhesion to propylene polymers and styrene polymers will be poor. On the other hand, when an ethylene-vinyl acetate copolymer with a copolymerization ratio exceeding 35% by weight is used, the odor of vinyl acetate is noticeable as described above.
Lacks thermal stability and extrusion stability. MFR of this ethylene-vinyl acetate copolymer
(measured according to JIS K6730) is 0.5 to 40g/
10 minutes, preferably 1 to 30 g/10 minutes, particularly preferably 2 to 25 g/10 minutes. Ethylene-
If the MFR of the vinyl acetate copolymer is less than 0.5 g/10 minutes, the kneading properties of the propylene polymer and the block copolymer of styrene and conjugated diene will be poor, and it will be difficult to obtain a homogeneous composition. Variations occur in adhesion. On the other hand, MFR
If an ethylene-vinyl acetate copolymer with a temperature exceeding 40 g/10 minutes is used, the resulting composition will have a high melt flow rate and poor molding stability. (C) Block copolymer of a vinyl aromatic compound and a conjugated diene Furthermore, the block copolymer of a vinyl aromatic compound and a conjugated diene used in the present invention is a block copolymer of a vinyl aromatic compound and a conjugated diene. - It is a block copolymer with a vinyl aromatic compound such as methylstyrene or vinyltoluene (among which styrene is preferred), and the forms of the block include single block copolymer, teleblock copolymer, and radial teleblock copolymer. Polymers, multi-block copolymers, etc. may be used, and any of these block copolymers may be used. The copolymerization ratio of the vinyl aromatic compound in the block copolymer is usually 5 to 85% by weight, preferably 5 to 80% by weight, and particularly preferably 10 to 80% by weight. If the copolymerization ratio of the vinyl aromatic compound is less than 5% by weight, the adhesiveness with the styrene resin will be poor. on the other hand,
If it exceeds 85% by weight, the adhesiveness of the propylene polymer will be poor. In addition, the melt index of this block copolymer (according to ASTM D1238, the conditions are E
(hereinafter referred to as "MI") is 20 g/10 minutes or less, preferably 10 g/10 minutes or less, and particularly preferably 0.01 to 10 g/10 minutes. MI is 20
If you use a block copolymer that exceeds g/10 minutes,
The resulting composition has a high melt flow rate and poor molding stability. (D) Composition ratio The composition ratio of the propylene polymer in the composition obtained by the present invention is 1 to 20% by weight,
2 to 20% by weight is preferred, particularly 5 to 20% by weight. If the proportion of the propylene polymer in the composition is less than 1% by weight, not only the resulting composition will have poor adhesion to the propylene resin, but also the heat resistance of the composition will be poor. On the other hand, if it exceeds 20% by weight, the adhesion of the resulting composition to the styrene resin will decrease. That is, the purpose of blending the propylene polymer in the above composition range in the present invention is to provide adhesiveness with the propylene resin and further improve heat resistance. In addition, the composition ratio of the block copolymer of a vinyl aromatic compound and a conjugated diene is 1 to 25% by weight, preferably 2 to 25% by weight, especially 5 to 25% by weight.
25% by weight is preferred. Even if the proportion of the block copolymer in the composition is less than 1% by weight or more than 25% by weight, the adhesion to styrene resins is particularly poor. From the above, the composition ratio of the ethylene-vinyl acetate copolymer in the composition of the present invention is 55%.
~98% by weight, preferably 55-96% by weight,
Particularly suitable is 55 to 90% by weight. In the present invention, the reason why the ethylene-vinyl acetate copolymer is blended within the above composition ratio range is to simultaneously improve the adhesive strength between the olefin resin and the styrene resin, and even if the upper limit is exceeded, the lower limit Even if it is less than that, the adhesion with these resins is not good. (E) Production of composition, molding method, etc. In producing the composition of the present invention, the above-mentioned propylene polymer, ethylene-vinyl acetate copolymer, and block copolymer of a vinyl aromatic compound and a conjugated diene are used. They may be mixed uniformly within the above composition ratio range. At this time, heat or oxygen stabilizers, lubricants, plasticizers, fillers, antistatic agents, flame retardants, pigments (colorants) may be used within the range that does not essentially lose the properties of the composition of the present invention. Additionally, additives such as adhesion promoters may be added. The mixing method is a Henschel mixer, which is widely used in the field of thermoplastic resins.
Dry blending may be performed using mixers such as ribbon mixers and tumblers, or melt kneading may be performed using mixers such as Banbury mixers, kneaders, roll and screw extruders. Among these, the latter method of melt kneading is more preferred as a means of obtaining a more uniform composition, and from an economical point of view, mixing using a screw extruder is preferably employed. Further, if necessary, the product may be passed through a screw extruder two or more times. The composition of the present invention obtained as described above is
Since both propylene resin and styrene resin have excellent adhesive properties, they may be laminated with a molded product of either of these resins as described later, and the composition of the present invention may be laminated with a molded product of either of these resins as described below. They may be laminated with a molded product interposed therebetween. moreover,
Examples of these molded products include film-like products and sheet-like products, but foamed products may also be used in the case of styrene resins. Whether the composition of the present invention is melt-kneaded or molded from the composition, the propylene polymer, ethylene-vinyl acetate copolymer, and vinyl aromatic components that are the constituent components of the composition are It is necessary to conduct the test at a temperature at which the block copolymer of the group compound and the conjugated diene melts. but,
It must be carried out at a temperature at which these components do not decompose thermally. Therefore, the above treatments (melt kneading, molding, etc.) must be carried out at a temperature range of 160 to 300°C (preferably 160 to 250°C). Similarly, when a molded product of the composition of the present invention and a molded product of styrene resin and/or olefin resin as other laminated components are laminated as described below, heat bonding or side-deutschematic lamination may be used at a temperature of 160°C or higher. However, it can be carried out at a temperature of 300°C or lower. In producing a laminate of the molded product of the composition of the present invention and other laminate components, a two- or three-layer molded product (laminate) is produced in advance by heat melting, and then this molded product is Although it is possible to obtain a desired multilayer structure using a method, this method requires many steps to obtain a multilayer structure, and is not economically preferable. Examples of methods for producing a laminate of a molded product of the composition of the present invention and other laminate components include the generally practiced thermal adhesion method and Sand-German lamination method. Alternatively, a laminate of a molded product of the composition of the present invention and a molded product of another laminated component may be produced in advance, and then laminated with a molded product of the other laminated component. The thermal bonding method uses generally known heat supply methods such as high-pressure steam, electric heating, or rolls with heated oil circulating, as well as methods that use ordinary infrared heaters, far-infrared heaters, or ovens equipped with electric heaters. However, as an economical method, thermal bonding using a roll is preferred. In addition, as another bonding method, a styrene resin base material is manufactured in advance, and a molded article (for example, a film) of the composition of the present invention and an olefin resin molded article are attached to the styrenic resin base material. A molded product of two types and two layers, or a molded product of styrene resin, a molded product of three types and three layers, consisting of a molded product of the composition of the present invention and a molded product of olefin resin, by thermal bonding method or Sand-German tiramination. Furthermore, there is a method in which a styrene resin base material and a propylene resin molded article are produced in advance, and the composition of the present invention is melt-extruded between them through a T-die. In any of the above methods, it is necessary to carry out the process at a temperature of 160° C. or higher, and if the temperature is lower than 160° C., the adhesion becomes poor and is unsatisfactory for practical use. Among these methods, there is no need to specify an upper limit temperature, but if the propylene polymer that forms the surface layer is completely melted, the appearance or commercial value will be poor, so ,190℃
It is desirable to carry out the following). However, since a continuous bonding process is normally employed, the optimum conditions are determined by the line speed or the total thickness of the laminate. The final laminate obtained in the above manner may have two layers consisting of a layer of the composition of the present invention and a styrene resin layer or an olefin resin layer. In addition, it may be composed of three or more layers each having at least one layer of the composition of the present invention, a styrene resin layer, and an olefin resin layer (in this case, there is a layer between the styrene resin layer and the olefin resin layer). layer of the composition of the invention). The total thickness of the laminate thus obtained is not particularly limited, but is usually 20 microns or more, and from the viewpoint of practical oil resistance and heat resistance, the propylene polymer layer is preferably 20 microns or more. The laminate obtained as described above may be used in the form of a sheet, or may be formed into a desired container depending on the intended use. When the surface layer of the laminate thus obtained is an olefin resin layer, it is possible to obtain a laminate that not only has good heat resistance but also excellent oil resistance. In addition, when the surface layer is made of styrene resin, a laminate not only rich in gloss but also excellent in hardness can be obtained. EXAMPLES AND COMPARATIVE EXAMPLES The present invention will now be explained in more detail with reference to Examples. In the Examples and Comparative Examples, the adhesive strength was measured using a Tensilon type tensile tester, and the peeling speed was
The resistance was determined by peeling in a direction of 180 degrees at a rate of 100 mm/min and measuring the resistance value. In addition, for the oil resistance test, the molded product was placed in a tray container filled with 1/2 water and 1/5 of cooking oil on top, then placed in a microwave oven and heated to 130℃ for 3 minutes.
The appearance was judged. In addition, in the examples and comparative examples, the ethylene content is 2.0% by weight as a propylene polymer.
An ethylene-propylene random copolymer (MFR 8.2 g/10 minutes, hereinafter referred to as "PP") was used. Further, as the ethylene-vinyl acetate copolymer, an ethylene-vinyl acetate copolymer (MFR 4.1 g/10 minutes, hereinafter referred to as "EVA") having a vinyl acetate content of 18% by weight was used. Furthermore, as a block copolymer of styrene and conjugated diene, a styrene-butadiene-styrene block copolymer (MFR 2.5) with a styrene content of 40% by weight is used.
g/10 minutes, hereinafter referred to as "SBS") was used. For comparison, styrene-butadiene copolymer rubber (hereinafter referred to as "SBR") with a styrene content of 25% by weight was used.
The content of styrene-isoprene-styrene block copolymer (hereinafter referred to as "SIS") and ethyl acrylate is 20% by weight, and the melt flow index (ASTM D1238 method) is 20%.
An ethylene-ethyl acrylate copolymer (hereinafter referred to as "EEA") having a yield of 100 g/10 min was used. Examples 1 to 9, Comparative Examples 1 to 7 PP, EVA and SBS whose blending amounts are shown in Table 1 were dry blended in advance for 5 minutes using a Henschel mixer. Each of the obtained mixtures was melt-kneaded using an extruder at a temperature of 200°C to produce compositions (pellets) (Examples 1 to 9, Comparative Examples 1 to 4). In order to examine the adhesion of the above composition with styrene resin and propylene polymer, an extruder equipped with three types and three layers of T-dies was used, and the molding temperature was 220°C.
℃ and line speed of 10 m/min.
Styrene homopolymer (GP) with an MFR of 3.0 g/10 min as the outer layer, and the above composition or
SBR (Comparative Example 5), SIS (Comparative Example 6) or EEA
(Comparative Example 7) and MFR as inner layer is 10g/10
A film (laminate) of three types and three layers with a total thickness of 100 microns (constituent ratio 1:1:2) was produced using propylene homopolymer (PP). The thus obtained film was peeled off between the outer layer (PS) and the middle layer, and between the middle layer and the inner layer, and the adhesive strength was measured. The results are shown in Table 1.

[Table] Examples 10 to 18, Comparative Examples 8 to 11 Composition manufactured in Example 2 [hereinafter referred to as "()"], Composition manufactured in Example 5 [hereinafter referred to as "()"]
], SBS used in Comparative Example 3 [hereinafter referred to as "()"]
] or the composition produced in Comparative Example 4 [“()”
A two-layer coextruded film (thickness: 30 microns) and a propylene homopolymer film (thickness: 60 microns) with an MFR of 10 g/10 minutes, and a melt flow index (according to JIS K6870). Therefore, measurement) or 3
g/10 minutes polystyrene film (30 microns thick, as outer layer), a film (20 microns thick, as middle layer) of the composition produced in Example 9 (hereinafter referred to as "()"), and the propylene single weight. A three-layer coextruded film consisting of a combined film (50 microns thick, as the inner layer) was produced. A polystyrene sheet (hereinafter referred to as "PSS") and a foam (hereinafter referred to as "PSP") each having a thickness of 0.2 mm were added to the coextruded film obtained in this way, and the molding temperatures are shown in Table 2. They were bonded together using a hot roll and formed into a tray under the following conditions. The adhesive strength of PSS and PSP of the obtained tray was measured. The results obtained are shown in Table 2.
The obtained tray was also tested for oil resistance. No change was observed in any of the trays obtained in Examples 10 to 18. On the other hand, the trays obtained in Comparative Examples 8 and 9 peeled off at the adhesive surface. Furthermore, the tray obtained in Comparative Example 10 suffered partial peeling at the adhesive surface, and the tray obtained in Comparative Example 11 suffered partial peeling between the propylene homopolymer film and the adhesive layer. Furthermore, the SBR, SIS and
Coextruded films were produced in the same manner as in Example 10 using EEA in place of the film of the above composition, but the adhesive strength of PSS was low in all cases. In addition, an oil resistance test was conducted, but peeling was observed on all adhesive surfaces.

[Table] From the results of the above Examples and Comparative Examples, it is clear that the adhesive resin composition obtained by the present invention has good adhesion to both olefin resins and styrene resins. It is obvious that the laminate product obtained by interposing the molded product of the composition of the present invention between these molded products (film, sheet, etc.) has a bond strength at the interface of these laminated components that is higher than that of other materials. It is clear that it can be used in a wide variety of fields because it not only has a significantly higher oil resistance than that of the conventional oil, but also has excellent oil resistance. Effects of the Invention The adhesive resin composition of the present invention and the laminate product using the composition exhibit the following effects (characteristics) including their manufacturing process. (1) The composition has good adhesion to both olefin resins and styrene resins. (2) Like ethylene-vinyl acetate copolymer, it does not contain odor-producing compounds or resins such as vinyl acetate, so it not only has almost no odor, but also has good thermal stability and extrusion stability. It's also excellent. (3) Not only is the composition easy to manufacture, but also a laminate product can be easily manufactured by coextruding a film or sheet of the styrene resin or olefin resin and a film or sheet of the composition. be able to. In order to exhibit the above effects, the adhesive resin composition of the present invention can be formed into the above-mentioned laminate and used in a wide variety of applications. Typical uses include various trays, various containers such as cups and boxes.

Claims (1)

[Scope of Claims] 1 (A) At least one selected from the group consisting of a propylene homopolymer, a random copolymer of propylene and ethylene or an α-olefin, and a block copolymer of propylene and ethylene or an α-olefin. A kind of propylene polymer, (B) the content of vinyl acetate is 5 to 35% by weight,
A composition comprising a copolymer of ethylene and vinyl acetate having a melt flow rate of 0.5 to 40 g/10 minutes, and (C) a block copolymer of a vinyl aromatic compound and a conjugated diene, in which The composition ratio of the propylene polymer is 1 to 20% by weight, and the composition ratio of the block copolymer of a vinyl aromatic compound and a conjugated diene is 1 to 25% by weight, with the remainder being ethylene and vinyl acetate. An adhesive resin composition that is a copolymer with.