JPH0687191A - Laminate - Google Patents

Abstract

PURPOSE:To furnish a laminate prepared by bonding a styrene resin layer and a propylene resin layer in a strength enabling practical use thereof. CONSTITUTION:As a bonding layer between a styrene resin layer (a) and a propylene resin layer (b), a hydrogenated substance of a block copolymer of styrene and conjugated diene of which the melting viscosity at a resin temperature 210 deg.C and a shear rate 100sec<-1> is 1X10<3> to 1X10 poise (c) is used. Thereby the styrene resin layer and the propylene resin layer are bonded in a strength enabling practical use thereof and thereby a laminate of which the oil resistance and co-extrusion molding properties or vacuum forming properties are improved remarkably is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminate in which a styrene resin layer and a propylene resin layer are adhered with a practical strength.

[0002]

2. Description of the Related Art Styrenic resins have excellent characteristics such as good moldability, a material having a good balance of rigidity and impact resistance by adding a rubber component, and good printability. , Molded into various shapes and used in many fields of application. As one of them, a sheet-shaped product is subjected to secondary forming processing such as vacuum forming, pressure forming, hot plate pressure forming, etc., and is widely used in various containers.

However, styrenic resins cause stress cracking under the influence of oily substances such as fatty foods, and as a result, the physical properties of molded articles deteriorate sharply. In addition, since styrene resin is amorphous and its glass transition temperature is around 90 ° C,
It is easily deformed even at a relatively low temperature of ℃ or less. Furthermore, when used as a packaging material for an actual food product, both of these characteristics are combined, and the practical heat resistance temperature tends to be further lowered. Due to these drawbacks, styrene resins are considerably limited in practical fields.

For the purpose of solving the above problems, lamination of a propylene resin on a styrene resin has been studied. However, the two resins are incompatible with each other, and the interfacial adhesion between the two resins is poor if they are simply adhered.
Attempts have been made to obtain laminates by studying the materials that adhere to both layers.

For example, in JP-A-59-57748, a composition prepared by mixing a styrene-butadiene copolymer and a polyolefin at a specific ratio and using a polyethylene or an ethylene-propylene random copolymer in the same die. A method of extruding and laminating is described in JP-A-3-25884.
In JP-A-4, a composition in which 25 to 200 parts by weight of a polypropylene resin is added to 100 parts by weight of a block copolymer of styrene and a conjugated diene and / or a hydrogenated product thereof as an adhesive layer is laminated. The method for doing this is disclosed in
Japanese Patent No. 8843 discloses a method of laminating a three-component composition in which an unsaturated carboxylic acid and an α-olefin copolymer are added to the above structure.

However, in the method described in Japanese Patent Laid-Open No. 59-57748, the interfacial adhesion is poor and a large amount of unsaturated bonds are present, so that the thermal stability is poor and scorching occurs when coextruded into a multilayer sheet or the like. Therefore, practical application is difficult. In addition, JP-A-3-258844 and JP-A-3-25
According to the method described in Japanese Patent No. 8843, the thermal stability is greatly improved, but the interfacial adhesiveness is hardly improved, and only molded articles that are not put to practical use can be obtained.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a laminate in which a styrene resin layer and a propylene resin layer are bonded together with a practical strength.

[0008]

The present inventor has found that the resin temperature is 2
Melt viscosity at a shear rate of 100 sec ^-1 at 10 ° C is 1
It was found that a block copolymer hydrogenated product of styrene and a conjugated diene having a porosity of × 10 ³ to 1 × 10 ⁶ is specifically effective as an adhesive for a laminate of a styrene resin and a propylene resin, The present invention has been completed. According to the present invention, the above-mentioned problems are (1) as an adhesive layer between (a) a styrene resin layer and (b) a propylene resin layer, (c) a melt viscosity at a resin temperature of 210 ° C. and a shear rate of 100 sec ⁻¹ . 1 x 10 ³ to 1
A laminate comprising at least three layers, characterized by using a hydrogenated block copolymer of styrene and a conjugated diene having a poise of × 10 ⁶ ; (2) A laminate of (1) produced by coextrusion molding Can be solved by.

The present invention will be specifically described below. (A) Styrenic Resin The styrenic resin (hereinafter sometimes abbreviated as PS) in the present invention is a resin containing at least 25% by weight or more of the structural unit represented by the following general formula in the resin.

[Chemical 1] (Here, R is a hydrogen atom or a methyl group, Z is a halogen atom or a methyl group, and p is an integer of 0 or 1 to 3.) Specifically, polystyrene, rubber-modified polystyrene, styrene-butadiene copolymer Examples thereof include homopolymers and copolymers of styrene and its derivatives, which are exemplified by a polymer, a styrene-acrylonitrile copolymer, a styrene-butadiene-acrylonitrile copolymer, and the like. These can be used by blending with each other, and those obtained by blending these resins with styrene-conjugated diene block copolymer rubber and hydrogenated products thereof are also applied.

The molecular weight of the styrene resin can be determined by a general method such as gel permeation chromatography (hereinafter abbreviated as GPC). The number average molecular weight (hereinafter abbreviated as Mn) is usually 5,000 to 400,000, preferably 10,000 to 300,000,
Especially, those of 30,000 to 200,000 are preferable. The weight average molecular weight (hereinafter abbreviated as Mw) is usually 10,000 to 1,000,000, and 50,000
0 to 800,000 is desirable, especially 10
Those of 50,000 to 500,000 are suitable. Mn
If a styrene-based resin having a Mw of less than 5,000 or a Mw of less than 10,000 is used, the molten resin extruded from the die during sheet molding hangs due to its own weight, and the roll cannot be uniformly cooled, which makes sheet formation difficult. In addition, molded articles obtained by other molding methods cannot have practical physical properties. In addition, Mn is 400,00
If a styrene-based resin having a Mw of more than 0 or a Mw of more than 1,000,000 is used, it cannot be used because extrusion or injection molding cannot be performed due to poor fluidity during melting.

Further, Mw / Mn used as a measure of the molecular weight distribution is usually 1.0 to 20, preferably 1.5 to 10 can be used.

Melt index of styrene resin (J
Measured under condition 8 according to IS K7210.
(1) is usually 0.005 to 100 g / 10 minutes, preferably 0.01 to 80 g / 10 minutes,
Especially, those having 0.02 to 50 g / 10 minutes are preferable. If a styrene-based resin having an MI (1) of less than 0.005 g / 10 minutes is used, extrusion molding cannot be performed because of poor fluidity, and multilayer molding is difficult. On the other hand, if a styrene resin exceeding 100 g / 10 minutes is used, a good drawdown cannot be obtained when producing these extruded sheets.

(B) Propylene-based resin As the propylene-based resin (hereinafter sometimes abbreviated as PP) used in the present invention, propylene homopolymer, propylene and 20% by weight or less (preferably 18% by weight or less, preferably 15% by weight or less) and / or a copolymer obtained by randomly or block copolymerizing ethylene and / or another α-olefin having 12 or less (preferably 8 or less) carbon atoms.

Further, homopolymers of these propylene-based resins and ethylene, ethylene and α having 3 to 12 carbon atoms are used.
-A copolymer with an olefin, a mixture with a homopolymer of an α-olefin having 4 to 6 carbon atoms, a mixture of the above-mentioned propylene-based polymers, or at least one double bond in these propylene-based resins. A modified propylene-based resin obtained by graft-polymerizing a compound having a bond (for example, unsaturated carboxylic acid or vinylsilane compound) is also included. These propylene-based resins and modified propylene-based resins may be used alone or in combination of two or more.

The molecular weight of the propylene-based resin is a value determined by a general method such as the GPC method as in the case of the styrene-based resin, and Mn is usually 5,000 to 200,000.
Those of 10,000 to 150,000 are preferable, and those of 15,000 to 120,000 are particularly preferable.
The Mw is usually 10,000 to 1,000,000, preferably 50,000 to 800,000, and more preferably 100,000 to 600,000. Mn is less than 5,000 or Mw is 1
If less than 10,000 propylene-based resins are used, the molten resin extruded from the die during sheet molding will hang down, making sheet molding difficult and molded articles obtained by other molding methods will also have practical physical properties. You can't get what you have. On the other hand, when a propylene-based resin having an Mn of more than 200,000 or an Mw of more than 1,000,000 is used, extrusion molding cannot be performed because of poor fluidity, and sheet molding is difficult.

Further, Mw / Mn is usually 1.0 to 20, preferably 2 to 10 can be used.

The melt index of the propylene resin (measured according to JIS K7210 under the condition 14, hereinafter referred to as "MI (2)") is usually 0.005 to 100 g /
It is 10 minutes, preferably 0.01 to 80 g / 10 minutes, and more preferably 0.02 to 50 g / 10 minutes. When a propylene-based resin having an MI (2) of less than 0.005 g / 10 minutes is used, extrusion molding cannot be performed because of poor fluidity, and multilayer molding is difficult. On the other hand, 100 g /
If a propylene-based resin for more than 10 minutes is used, a good product with a large drawdown cannot be obtained when producing these extruded sheets.

(C) Styrene-conjugated diene block copolymer hydrogenated product The styrene-conjugated diene block copolymer hydrogenated product (hereinafter sometimes abbreviated as SEPS) used in the present invention comprises a vinyl aromatic compound. A block copolymer composed of a polymer block B composed of a conjugated block A and a conjugated diene compound, the block of which is obtained by hydrogenating a triblock copolymer having a bound vinyl aromatic compound content of 20 to 90% by weight. It is a hydrogenated block copolymer obtained by saturating 60% or more of double bonds in the copolymer.

The vinyl aromatic compound block A is a polymer composed of a styrene compound such as styrene, α-methylstyrene, and 2,4-dimethylstyrene, or a mixture thereof.

The conjugated diene compound block B is a polymer composed of butadiene, isoprene, an isoprene-butadiene copolymer, or a mixture thereof. Further, it is necessary that 50% by weight or more of the conjugated diene compound in the block B has a 1,4 structure, and preferably 7
It is 0% by weight or more. When less than 50% by weight of the material is used as an adhesive layer between a styrene resin layer and a propylene resin layer by adding a styrene resin, the adhesiveness is extremely lowered and it cannot be put to practical use.

In order for the styrene-conjugated diene block copolymer hydrogenated product to exhibit practically sufficient adhesiveness between the styrene resin and the propylene resin, specific melting characteristics are required. That is, the melt viscosity at a resin temperature of 210 ° C. and a shear rate of 100 sec ⁻¹ is 1 × 10 ³ to 1 ×.
10 ⁶ poise, preferably 2 × 10 ³ to 1 × 10
^{It is 5} poises, and particularly preferably 4 × 10 ^{3 to} 5 × 10 ⁴ poises. If it is less than 1 × 10 ³ poise, the resin viscosity is too low to obtain sufficient adhesiveness, and if it exceeds 1 × 10 ⁶ poise, the resin viscosity is too high and multilayer molding itself becomes impossible. The measurement nozzle diameter of the melt viscosity of 1.0mm, L / D = 40 nozzles using the relationship between shear rate and apparent viscosity measured at a resin temperature 210 ° C. at a shear rate of 100 sec ^-1 the graph of The viscosity was determined.

The binding form of the block copolymer consisting of the block A and the block B is not particularly limited, and may be, for example, an AB, ABA, ABBAB structure or the like. A block structure is available. Further, among them, a particularly preferable block structure is AB from the viewpoint of interfacial adhesion.
-A type triblock type.

The content of the bound vinyl aromatic compound in the block copolymer is 20 to 90% by weight, preferably 40.
˜85 wt%, preferably 50-75 wt%. When it is less than 20% by weight or more than 90% by weight, when a styrene resin is added and used as an adhesive layer between the styrene resin layer and the propylene resin layer, the adhesiveness is extremely lowered and it cannot be put to practical use. In addition, a blend composition using a conjugated diene compound block B having a hydrogenation of less than 60% also has only a very low adhesiveness during multi-layer molding and is not practical.

Furthermore, the molecular weight of the hydrogenated styrene-conjugated diene copolymer used in the present invention is usually 4,000 to 2.0.
0,000, preferably 10,000 to 1,0
0,000, preferably 30,000 to 500,
It is 000. If it is less than 4,000, the adhesiveness is low and the intended laminate cannot be obtained. If it exceeds 2,000,000, the viscosity is too high and the multilayer molding itself is difficult, which is not preferable.

(D) Inorganic Filler The resin composition of the present invention may contain any inorganic filler, if necessary. Inorganic fillers are generally widely used in the fields of synthetic resins and rubber. As these inorganic fillers, inorganic compounds that do not react with oxygen and water and that do not decompose during kneading and molding are preferably used.

When an inorganic filler is compounded, the compounding ratio of the inorganic filler in the total amount of the resin composition and the inorganic filler is generally at most 80% by weight, preferably 70% by weight or less, Particularly, 60% by weight or less is preferable. If the content of the inorganic filler in the total amount exceeds 80% by weight, it is difficult to form a sheet and a good sheet cannot be obtained.

(E) Method for producing laminated body The laminated body of the present invention has a styrene-conjugated diene block copolymer hydrogenated material layer between the styrene resin layer and the propylene resin layer, and further, if necessary. It is a laminated body of three or more layers having a recycled resin layer. For example, in the case of a multi-layer container, when oil resistance and heat resistance are required both inside and outside, a 3 type 5 layer structure in which a propylene resin layer is provided on both sides with an adhesive layer on both sides with a styrene resin layer in between is preferable. When the oil resistance and heat resistance are required on only one side, a simple three-kind three-layer structure is sufficient. The layer structure is not particularly limited as long as it satisfies the above structure.

These laminates are generally obtained by a known molding method. For example, coextrusion T-die molding is used for sheets and films, coextrusion circular die molding is used for sheets and films, and coextrusion hollow molding is used for containers and bottles. Shape can be easily formed by general molding processing methods such as co-injection molding and sandwich molding. In that case, for example, in the case of extrusion molding, in addition to melt blending the two components in advance as described above, the adhesive layer may be dry blended and molded.

The thickness of each layer is 3 for the styrene resin layer.
μm to 5 mm, preferably 50 μm to 3 mm, 2
00 μm to 1 mm is preferable. If the thickness is less than 3 μm, the rigidity is low and the container is not practical, and the thickness exceeding 5 mm is not economically and practically practical. The thickness of the propylene-based resin layer is 3 μm to 5 mm, 10 μm
˜3 mm is preferable, and 20 μm to 1 mm is preferable.
When the thickness is less than 3 μm, it is difficult to stack, and when the thickness exceeds 5 mm, the thickness is not economically and practically practical. The thickness of the hydrogenated styrene-conjugated diene block copolymer layer is 1 μm.
˜1 mm, preferably 3 μm to 500 μm, 5 μm
m to 300 μm is preferable. If it is less than 1 μm, it is difficult to form a uniform layer, and if it exceeds 1 mm, there is almost no effect on the improvement of the adhesiveness, which is not realistic in view of economy.

The extrusion temperature of the coextrusion molding for obtaining the laminate is generally 100 to 350 ° C, preferably 150 to 330 ° C, particularly preferably 180 to 300 ° C.

The resin used in each layer of the laminate of the present invention includes various additives which are usually added to propylene-based resin as required, such as a nucleating agent, an antioxidant, a heat stabilizer and an antistatic agent. , An ultraviolet absorber, a heavy metal stabilizer (copper damage inhibitor), a colorant, a flame retardant, a flame retardant aid, and the like can be appropriately used in combination.

[0032]

EXAMPLES The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. The evaluation methods used in the examples and comparative examples are as follows.

1) Melt viscosity By a capillograph manufactured by Toyo Seiki Co., Ltd., a diameter of 1 mm,
The viscosity at a shear rate of 100 sec ⁻¹ was measured at 210 ° C. using a capillary nozzle with L / D = 40.

2) Sheet Formability The appearance of the formed multi-layer sheet was visually evaluated, and those having the same level as ordinary sheets were evaluated as ◯, and those in which appearance changes such as layer disorder and skin roughness were observed were evaluated as x.

3) Peel strength between layers A test piece having a width of 15 mm and a length of 150 mm was cut out from the multilayer sheet and peeled by 180 ° with a tensile tester at a pulling speed of 50.
A peeling test was carried out under the condition of mm / min.

4) Vacuum Formability A multilayer sheet was manufactured with a vacuum forming machine manufactured by Asano Laboratory to a capacity of 9
A container of 0 cc (L / D = 0.4) was molded, and the molded state of the container was visually evaluated.
And, those in which appearance changes such as cracks, rough skin, and unevenness of growth were observed were marked with x.

5) Oil resistance A multilayer sheet was cut into a size of 50 × 50 mm and evaluated for appearance change after being immersed in olive oil for 7 days. The occurrence is marked as x.

(Examples 1 and 2) By the coextrusion molding method,
A multi-layered sheet of three types and three layers consisting of A: propylene resin layer, B: adhesive layer, and C: styrene resin layer was molded.
The components of each of the layers A to C are as follows. Layer A: MI (2) 10 g / 10 min, ethylene content 10
Ethylene-propylene random copolymer (PP-1) which is a weight%. Layer B: A triblock type hydrogenated styrene-isoprene block copolymer (SEPS-1) having a melt viscosity of 1 × 10 ⁴ poise and an amount of styrene of 60% by weight. Layer C: rubber-modified polystyrene (PS-) having MI (1) of 3.0 g / 10 minutes and a rubber content of 6.2% by weight.
1). A coextrusion multilayer sheet having the thickness constitution shown in Table 1 was molded using these components. The resin temperature during molding is about 210 ° C., the sheet thickness is 0.5 mm, and the width is 500 mm. Further, with respect to these sheets, sheet formability and delamination strength were evaluated. The evaluation results are shown in Table 1. It was found that each of the sheets obtained in these examples had a good sheet appearance and had a practical adhesive strength.

(Examples 3 and 4) Layer B has a melt viscosity of 1 × 1.
0 ⁵ a poise or 6 × 10 ³ poise, triblock type, styrene content 60 wt% styrene - isoprene block copolymer hydrogenated product (SEPS-2, SEPS-
A multilayer sheet was molded and evaluated in the same manner as in Example 1 except that the procedure was changed to 3). The results are shown in Table 1. It was found that each of the sheets obtained in these examples had a good sheet appearance and had a practical adhesive strength.

Example 5 Layer B has a melt viscosity of 1 × 10 ⁴
A multi-layer sheet was molded and evaluated in the same manner as in Example 1 except that it was a poise, triblock type, styrene-isoprene block copolymer hydrogenated product (SEPS-4) having a styrene content of 35% by weight. The results are shown in Table 1. It was found that each of the sheets obtained in this example had a good sheet appearance and had a practical adhesive strength.

Comparative Example 1 A multilayer sheet was molded and evaluated in the same manner as in Example 1 except that the styrene homopolymer used in the C layer of Example 1 was used as the B layer. The results are shown in Table 1. In this case, each layer of the sheet was disturbed, the surface was roughened, and the adhesive component was not present, so that the interlaminar peel strength was extremely low and a practical sheet could not be obtained.

(Comparative Examples 2 and 3) The melt viscosity of the B layer was 1 × 1.
0 ⁴ poise, triblock type, styrene amount 6
A multilayer sheet having the composition shown in Table 1 and in the same manner as in Example 1 except that the unhydrogenated styrene-isoprene block copolymers (SIS-1, SIS-2) of 0% by weight and 35% by weight were used. Was molded and evaluated. The results are shown in Table 1. In the sheet obtained by these, each layer was disturbed and the skin was roughened, and the interlaminar peel strength was low, and a practical sheet could not be obtained.

(Comparative Examples 4 and 5) The melt viscosity of the B layer was 1 × 1.
Triblock type, styrene-isoprene block copolymer hydrogenated product (SEPS-5, SEPS-) having 0 ² poise or 1 × 10 ⁷ poise.
An attempt was made to mold a multi-layered sheet with the composition shown in Table 1 in the same manner as in Example 1 except that the composition was changed to 6), but a sheet-shaped molded body was not obtained.

Example 6 By the coextrusion molding method, A,
A multi-layered sheet of 5 layers of 3 types consisting of E: propylene resin layer, B, D: adhesive layer, C: styrene resin layer was molded. The components of each of the layers A to E are as follows. A and E layers: PP-1 same as the A layer in Examples 1 to 5. Layers B and D: SEPS-1 which is the same as the layer B of Example 1. C layer: The same PS-1 as the C layer of Examples 1-5. A coextrusion multilayer sheet having the thickness constitution shown in Table 2 was molded using these components. The resin temperature during molding is about 210 ° C., the sheet thickness is 0.7 mm, and the width is 500 mm. Further, this sheet was evaluated for sheet formability, vacuum formability, and oil resistance. The evaluation results are shown in Table 2. It was found that the sheet thus obtained had a good sheet appearance and also had good vacuum formability and oil resistance.

(Example 7) A multilayer sheet was molded and evaluated in the same manner as in Example 6 except that SEPS-3 used in the B layer in Example 4 was used in the B and D layers. The results are shown in Table 2. It was found that the sheet thus obtained had a good sheet appearance and also had good vacuum formability and oil resistance.

Example 8 A multilayer sheet was molded and evaluated in the same manner as in Example 6 except that SEPS-4 used in the B layer of Example 5 was used in the B and D layers. The results are shown in Table 2. It was found that the sheet thus obtained had a good sheet appearance and also had good vacuum formability and oil resistance.

Comparative Example 6 A multilayer sheet was molded and evaluated in the same manner as in Example 6 except that the styrene homopolymer used in the C layer of Example 1 was used as the B and D layers. The results are shown in Table 2. It was found that in the sheet thus obtained, each layer was disturbed, the surface was roughened, and delamination occurred during vacuum forming due to the absence of an adhesive layer, so that the oil resistance was extremely low and it was poor in practical use.

[0047]

[Table 1]

[0048]

[Table 2]

[0049]

EFFECTS OF THE INVENTION The laminate obtained by the present invention is excellent in sheet secondary processability such as vacuum forming, pressure forming and hot plate pressure forming, and is also excellent in heat resistance and oil resistance. It is a material. As a field of use thereof, not only packaging materials such as sheets and films, but also home appliances parts, automobile parts and various industrial parts can be suitably molded and used.

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Claims (2)

[Claims] 1. An adhesive layer between (a) a styrene resin layer and (b) a propylene resin layer, and (c) a resin temperature of 210.
Melt viscosity at a shear rate of 100 sec ^{-1 at} ℃ 1 × 1
A laminate comprising at least three layers, wherein a hydrogenated product of a block copolymer of styrene and a conjugated diene having a porosity of 0 ³ to 1 × 10 ⁶ is used. 2. The laminate according to claim 1, which is produced by coextrusion molding.