JPH03224735A - Multilayer molded body - Google Patents

Abstract

PURPOSE:To obtain a multilayer molded body having sufficient barrier properties and impact resistance and consisting of a polyolefin layer and a polyamide resin layer both of which are well bonded by forming a barrier layer from a resin prepared by adding a specific modified olefinic elastomer to polyamide and forming an adhesive layer from the same unsaturated carboxylic acid modified polyolefin as a main layer. CONSTITUTION:A multilayer molded body is formed by bonding a polyolefin layer and a polyamide resin layer by a modified polyolefin layer. The polyolefin layer is composed of crystalline polyolefin and the polyamide resin layer consists of 51-80vol.% of polyamide and 49-20vol.% of a modified olefinic elastomer containing 1.0X10<-5>-6.0X10<-5>mol./g of unsaturated carboxylic acid or an anhydride thereof and the modified polyolefin layer is composed of the same crystalline polyolefin as the polyolefin layer modified with unsaturated carboxylic acid or an anhydride thereof. The multilayer molded body is prepared by molding a cylindrical parison having a multilayer structure by co-injection molding and arranging the same to a mold having a cavity of a desired shape to perform blow molding.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a multilayer molded article, and more particularly to a multilayer molded article having excellent impact resistance and barrier properties and having a polyamide layer and a polyolefin layer.

[Prior Art and Problems to be Solved by the Invention] Polyolefin resins are inexpensive and have high strength, so they are widely used in the manufacture of various containers. However, it could not be used for fuel tanks such as gasoline because its barrier properties were insufficient. Therefore, attempts have been made to use polyolefin as the main layer and polyamide as the barrier layer, but since the adhesive strength between the polyolefin layer and polyamide layer is weak, polyolefin resin is used as an adhesive layer between these two layers using unsaturated carboxylic acid. Various methods have been proposed for laminating layers with a modified plastic layer interposed (Japanese Unexamined Patent Publication No.
No. 8-220738, No. 62-110526, etc.).

However, since polyamide has lower impact resistance than polyolefin, a multilayer molded article having a polyamide layer has a problem in that the impact resistance is significantly reduced.

Furthermore, JP-A No. 55-91634 discloses (a) a polyolefin resin layer, (b) crystallinity of 1 to 35%, melt index of O, O of 1 to 50 g/10 min.
(C) A polyamide resin layer made of a molten mixture of a modified polymer obtained by grafting maleic anhydride onto an α-olefin copolymer (maleic anhydride content 0.05 to 1% by weight) and nylon. Ethylene/winter olefin copolymer with a crystallinity of 2-30% and a melt index of 0.01-50 g/10 min is grafted with maleic anhydride (maleic anhydride content 0.01-1% by weight). Laminated through a modified polyolefin resin layer consisting of a coalesce,
A multilayer molded product with little decrease in strength even when Paris is used as a raw material is disclosed.

However, the multilayer molded article has a problem in that the impact resistance of the polyamide resin layer is not sufficiently improved.

Therefore, an object of the present invention is to provide a multilayer molded article having sufficient barrier properties and impact resistance, and in which a polyolefin layer and a polyamide resin layer are well adhered to each other via an adhesive layer.

[Means to solve the problem]

As a result of intensive research in consideration of the above problems, the present inventors made a barrier layer using a resin made by adding a specific modified olefin elastomer to polyamide, and created an unsaturated carboxylic acid-modified product of the same polyolefin as the crystalline polyolefin layer, which is the main layer. It was discovered that the above object could be achieved by using an adhesive layer, and the present invention was conceived.

That is, in the multilayer molded article of the present invention, a polyolefin layer and a polyamide resin layer are bonded together by a modified polyolefin layer, the polyolefin layer is made of crystalline polyolefin, and the polyamide resin layer is made of 51 to 80% by volume of polyamide. and the content of unsaturated carboxylic acid or its anhydride is 1.0 x 10-5 to 6. OX 10-5mo
The modified polyolefin layer is made of the same crystalline polyolefin as the polyolefin layer modified with an unsaturated carboxylic acid or its anhydride. .

The present invention will be explained in detail below.

In the present invention, polyolefins forming the crystalline polyolefin layer include ethylene, propylene, butene-
1. Homopolymers of α-olefins such as hexene-1,4-methylpentene-1, copolymers of ethylene and propylene or other α-olefins, or copolymers of two or more of these α-olefins Examples include merging. Among these, high density polyethylene and polypropylene are preferred. Also, high density polyethylene or polypropylene,
It may also be a copolymer with the other polymers mentioned above, containing 60% by weight or more of high-density polyethylene or polypropylene. These crystalline polyolefins have a crystallinity (X
(as determined by linear analysis method) is preferably 35% or more, particularly preferably 50% or more. When the degree of crystallinity is less than 35%, impact resistance decreases unexpectedly when a multilayer molded product is formed.

Polypropylene is not limited to a homopolymer, and random or block copolymers with other α-olefins containing a propylene component of 50 mol% or more, preferably 80 mol% or more can also be used. Comonomers copolymerized with propylene include ethylene and other α-olefins, with ethylene being particularly preferred. Therefore, the term "polypropylene J" used herein is not limited to homopolymers of propylene, but should be understood to include copolymers as well.

When using high-density polyethylene as the polyolefin, its melt index (M 190℃, 2.1
6 kg load) is preferably 0.003 to 2 g/10 minutes. More preferably 0.001-1 g
/10 minutes. In addition, High Road Meltoia 7'-
/ When expressed in x (HLMI, 190" C121, 6 kg load), it is preferably 70 g/10 minutes or less, more preferably 1 to 20 g/10 minutes. Also, when polypropylene is used, its melt flow rate) (
MFR230℃, 2.16kg load) is 0.02 to 3
g/10 min, more preferably 0.02 to Ig/10
In the present invention, the polyamide resin layer is preferably in the range of 100 to 100%.

Examples of the polyamide include hexamethylene diamine, te'camethylene diamine, dodecamethylene diamine, 2.
2.4- or 2.4,4. -) aliphatic such as dimethylhexamethylenediamine, 1,3- or 1,4-bis(aminomethyl)cyclohexane, bis(p-aminocyclohexylmethane), m- or p-xylylenediamine, Polyamide resins produced from alicyclic or aromatic diamines and aliphatic, alicyclic or aromatic dicarboxylic acids such as adipic acid, speric acid, sebacic acid, cyclohexanedicarboxylic acid, terephthalic acid, isophthalic acid. , polyamide resins made from aminocarboxylic acids such as 6-aminocaproic acid, 11-aminoundecanoic acid, 12-aminododecanoic acid, ε-caprolactam,
Examples include polyamide resins produced from lactams such as ω-dodecalactam, copolyamide resins made of these components, or mixtures of these polyamide resins. Specifically, nylon 6, nylon 66, nylon 11. Examples include nylon 12 and copolymers thereof. Furthermore, a copolymer of 60% by weight or more of these nylon resins and the other resins mentioned above can be used.

The relative viscosity of the polyamide is preferably in the range of 1.0 to 10, particularly preferably in the range of 3.0 to 8.0.

In the present invention, the modified olefin elastomer is an olefin elastomer modified with an unsaturated carboxylic acid or its anhydride. Examples of unsaturated carboxylic acids or their anhydrides include monocarboxylic acids such as acrylic acid and methacrylic acid, dicarboxylic acids such as maleic acid, fumaric acid, and itaconic acid, maleic anhydride, itaconic anhydride, and endic anhydride (hymic anhydride). dicarboxylic acid anhydrides such as dicarboxylic acids), and dicarboxylic acids and their anhydrides are particularly preferred. Specifically, olefin elastomers modified with maleic anhydride or endic anhydride (himic anhydride) are particularly preferred.

In addition, olefin elastomers modified with unsaturated carboxylic acids or their anhydrides include ethylene, propylene,
α of ■-butene, ■-hexene, 4-methylpentene, etc.
- Means a copolymer rubber of two or more olefins, especially ethylene-propylene copolymer rubber (BPR)
and ethylene-butene copolymer rubber (BBR) are preferred.

The ethylene-propylene copolymer (BPR) rubber used in the present invention has a content of repeating units derived from ethylene of 10 to 90 mol% and a content of repeating units derived from propylene of 90 to 10 mol%. It is preferable that A more preferable range is 20 to 80 mol% of the ethylene repeating unit and 80 to 20 mol% of the propylene repeating unit.

Further, the Mooney viscosity ML of 8PR (at 100°C) is preferably in the range of 1 to 120, more preferably 5 to 100.

In the present invention, ethylene-butene copolymer rubber (EB
R) is a block copolymer with a butene-1 content of 10 to 90% by weight, particularly a butene-1 content of 20 to 90% by weight.
80% by weight is preferred.

Mooney viscosity ML of the above ethylene-butene copolymer rubber
, , (100°C) is preferably in the range of 1 to 120, more preferably 5 to 100.

In addition, in the present invention, ethylene-propylene copolymer (
BPR) and ethylene-butene copolymer rubber (BBR)
basically consists of the above repeating units,
Copolymers containing other resin components can also be used within a range that does not impair the properties of these copolymers.

The content of unsaturated carboxylic acid or its anhydride in the modified olefin elastomer is 1.0X10-6 to 6.
OX 10-'mol/g, preferably 2. OXl0
-5 to 5, OX 10-'mol/g. For example, when modifying with maleic anhydride, the content of maleic anhydride is 0.098 to 0.588% by weight, preferably 196 to 0.490% by weight, and when using Himic anhydride, , its content from 0.168 to
1.008% by weight, preferably 0.336-0.840
Weight%. If the amount of modification by unsaturated carboxylic acid or its anhydride is less than the above lower limit, the modified olefin elastomer will not be sufficiently compatible with the polyamide, and if it exceeds the upper limit, the modified olefin elastomer will not be able to dissolve into the polyamide. Difficult to uniformly disperse.

The modified olefin elastomer can be produced by either a solution method or a melt-kneading method.

In the case of the melt-kneading method, the olefin elastomer, unsaturated carboxylic acid for modification (or acid anhydride), and catalyst are put into an extruder, twin-screw kneader, etc., and heated to a temperature of 130 to 300 ° C. while melting. Knead. In addition, in the case of a solution method, the above starting material is dissolved in a organic solvent such as xylene, and the
It is carried out with stirring at a temperature of 0°C. In either case, ordinary radical polymerization catalysts can be used as catalysts, such as benzoyl peroxide, lauroyl peroxide, di-tert-butyl peroxide, acetyl peroxide, tertiary-butyl peroxide, etc.
Peroxides such as butylperoxybenzoic acid, dicumyl peroxide, peroxybenzoic acid, peroxyacetic acid, tert-butyl peroxybeverley), 2,5-dimethyl-2,5-'; tert-butyl peroxyhexine, Diazo compounds such as azobisisobutyronitrile are preferred. The amount of the catalyst added is about 1 to 100 parts by weight per 100 parts by weight of the unsaturated carboxylic acid for modification or its anhydride.

The modified olefin elastomer obtained in this way usually weighs 0.07 to 3000 kg/cn! It has a tensile modulus of elasticity.

The blending ratio of the above-mentioned polyamide and modified olefin elastomer in the polyamide resin is 51 to 80% by volume, preferably 55 to 80% by volume of polyamide, 49 to 20% by volume of modified olefin elastomer,
Preferably it is 45 to 20% by volume.

If the polyamide content is less than 51% by volume (if the modified olefin elastomer is more than 49% by volume), the Paris properties of gasoline etc. will decrease, and if the polyamide content exceeds 80% by volume (if the modified olefin elastomer is less than 20% by volume) ), impact resistance decreases.

In the present invention, the modified polyolefin that serves as the adhesive layer between the above-mentioned polyolefin layer and polyamide layer is a polyolefin modified with an unsaturated carboxylic acid or its anhydride. As the unsaturated carboxylic acid or its anhydride, those similar to those of the above-mentioned modified olefin elastomer can be used.

In addition, polyolefins modified with unsaturated carboxylic acids or their anhydrides are not limited to homopolymers of α-olefins as well as copolymers with other α-olefins, similar to the polyolefins forming the crystalline polyolefin layer described above. Also included. However, in the present invention, the polyolefin modified with the unsaturated carboxylic acid or its anhydride is the same as the polyolefin forming the crystalline polyolefin layer. Further, the degree of crystallinity is preferably 35% or more, particularly preferably 50% or more.

When the degree of crystallinity is less than 35%, impact resistance decreases unexpectedly when a multilayer molded product is formed. By using such a modified polyolefin, sufficient adhesion and impact resistance to the polyolefin layer can be achieved.

The content of unsaturated carboxylic acid or its anhydride in the modified polyolefin is 2. OXl0-' ~2. OXl0-'
mol/g is preferred, especially 4. OXl0-' ~1.
OXl0-'mol/g is preferred. For example, when modifying with maleic anhydride, the content of maleic anhydride is 0.0196 to 1.96% by weight, more preferably 0.
．． 0392 to 0.98% by weight, and when Himic anhydride is used, the content is 0.0328 to 3.28%.
% by weight, more preferably 0.0656-1.64% by weight
shall be.

If the amount of modification by unsaturated carboxylic acid or its anhydride is less than the above lower limit, the adhesion effect with the polyamide layer will not be sufficient, and if it exceeds the upper limit, the adhesion with the polyolefin layer will decrease. .

The modified polyolefin can be produced by either the solution method or the melt-kneading method, similar to the production of the above-mentioned modified olefin elastomer. In the case of the melt-kneading method, the polyolefin, unsaturated carboxylic acid for modification (or acid anhydride), and catalyst are charged into an extruder or twin-screw kneader, and the
The mixture is heated to a temperature of °C and kneaded while melting. In the case of a solution method, the starting material is dissolved in an organic solvent such as xylene, and the solution is stirred at a temperature of 80 to 140°C.

The multilayer molded article of the present invention is composed of the above-mentioned layers, and the resin for each shoe contains fillers such as inorganic fillers and carbon black, as well as other additives for the purpose of modifying the resin. heat stabilizers, light stabilizers, flame retardants, plasticizers,
Antistatic agents, mold release agents, foaming agents, nucleating agents, etc. can be added.

The multilayer molded article of the present invention has a layered structure as shown in FIG. 1, for example. In FIG. 1, the multilayer molded body consists of polyolefin layers 1, 1, a polyamide layer 2, and a modified polyolefin layer 3.3 that adheres both layers.

Such a multilayer molded product can be produced by, for example, molding a cylindrical parison having the above-mentioned layered structure by co-injection molding or the like, placing this parison in a mold having a cavity of a desired shape, and then blow molding it. can be manufactured.

The thickness of each layer may be set appropriately depending on the impact resistance and barrier properties required depending on the purpose of use, but for example, in the case of a gasoline tank, the thickness of the polyolefin layer is 0.5 to 10 mm, 0.005~l
mm, and the modified polyolefin layer may have a thickness of 0.005 to 1 mm.

[For production]

In the present invention, between the polyamide resin layer containing a predetermined amount of a modified olefin elastomer containing an unsaturated carboxylic acid or its anhydride and the crystalline polyolefin layer, the same crystalline polyolefin as the above polyolefin layer is used. Since the modified material is present, the adhesion between the polyamide resin layer and the polyolefin layer is good, there is no decrease in impact resistance, and the barrier properties are also good.

The reason why such an effect is obtained is not necessarily clear, but by blending a modified olefin elastomer with a specified content of unsaturated carboxylic acid or its anhydride into polyamide, the barrier properties of the polyamide layer are reduced. Furthermore, by configuring the modified polyolefin layer with the same crystalline polyolefin as the polyolefin layer modified with an unsaturated carboxylic acid or its anhydride, the polyamide layer, modified This seems to be because the interlayer adhesion strength of each of the polyolefin layer and the polyolefin layer becomes sufficient.

〔Example〕

The present invention will be explained in further detail by the following examples.

The following polyolefins, olefin elastomers, polyamides, and modified polyolefins were used as raw materials for each layer.

[1 Copolyolefin High Density Polyethylene HDPE: [: Tonen Petrochemical ■ 85742, High Road Melt Index (HLMI, 190°C, 21.
6kg load 5g/10 minutes, density 0, 945 g/ci
] [2] Olefin elastomer ■ Ethylene-propylene copolymer rubber EPR: [Mitsui Petrochemicals ■ XR106L, tensile modulus 1580 kg/cur] ■ Ethylene-butene copolymer rubber EBR: [Mitsui Petrochemicals ■ A-4085, Tensile modulus 90kg/cffll [3] Polyamide nylon 6 PA-1: [CM1046 manufactured by Toshi ■, density 1.1
3 g/cof] [4] Modified polyolefin CMPE: [0.4% by weight of maleic anhydride in H[lPH in the polyolefin column (4,08X 10-'mo
l/g) added, melt index (ML
190°C, 2.16 kg load) 0.3 g/10 min] Synthesis of modified olefin elastomers Himic anhydride or maleic anhydride and EPR or EBR are mixed in the proportions shown in Table 1, and then Himic anhydride or maleic anhydride is mixed with EPR or EBR. or 5 parts per 100 parts of maleic anhydride
Add parts by weight of Perhexine 25B (reaction initiator),
These were put into a single-screw kneader (65 mmφ, L1036) and melt-kneaded at 235° C. and 60 rpm to obtain a modified olefin elastomer.

Synthesis of polyamide resin The above modified olefin elastomer and nylon 6 (
PA-1) in the ratio shown in Table 1, put this into a twin-screw kneader (44 mmφ, L1032), and heated at 250°C.
, melt-kneaded at 25 Orpm to form polyamide resin 2~
5 (PA2-5) was obtained.

Using the polyamide resins (PA-1 to PA-5), high-density polyethylene, and modified polyolefin, a parison consisting of five layers of three types as shown in Fig. 1 was molded,
A container with a capacity of 40β was made by blow molding.

Here, the innermost and outermost layers (layer 1.1 in Figure 1) are made of high-density polyethylene, the intermediate layer (layer 2 in Figure 1) is polyamide resin, and the adhesive layer (layer 3.3 in Figure 1) is made of high-density polyethylene. ) using modified high-density polyethylene.

The thickness of each layer is 1.8 mm for the outermost layer and the innermost layer.

The intermediate layer was 0.1 mm thick, and the modified polyethylene adhesive layer was each 0.1 mm thick.

For comparison, a container was similarly molded using modified low-density polyethylene instead of modified high-density polyethylene for the adhesive layer, and a mixture of polyamide and modified polyolefin for the intermediate layer (Comparative Example 4).

A drop impact test was conducted on this fuel tank in the following manner.

Fill the fuel tank with water to full capacity, and after sealing the tank, drop the tank from each height shown in Table 3 with the bottom of the tank as the falling direction.
We investigated whether the fuel tank was destroyed or not. The results are shown in Table 3.

Gasoline barrier properties were also evaluated.

The gasoline barrier property was evaluated by the amount of gasoline permeated after filling a fuel tank with 401 regular gasoline and holding it for - days. The results are shown in Table 3.

As is clear from Table 3, the fuel tank made of the multilayer molded article of the present invention has good gasoline barrier properties and drop VI impact properties.

On the other hand, the multilayer molded article of Comparative Example 1 in which the intermediate layer was made of a single polyamide did not have sufficient drop impact resistance.

Furthermore, the multilayer molded article of Comparative Example 2, in which the intermediate layer was made of a resin in which a modified olefin elastomer with a too low acid addition rate was blended with polyamide, had poor impact resistance. This is considered to be because when the acid addition rate is too low, the compatibility of the modified olefin elastomer with the polyamide is too low.

On the other hand, the multilayer molded article of Comparative Example 3 in which the intermediate layer was made of a resin in which a modified olefin elastomer with an excessively high acid addition rate was blended with polyamide had poor gasoline barrier properties. This is thought to be because if the acid addition rate is too high, the modified olefin elastomer tends to be unevenly distributed in the polyamide, thereby impairing the barrier properties of the polyamide.

Furthermore, the multilayer molded article of Comparative Example 4 in which a modified polyolefin was blended into the polyamide resin layer, a modified low-density polyethylene in the adhesive layer, and a high-density polyethylene in the outermost layer did not have sufficient impact resistance. This is considered to be because the impact resistance of the polyamide resin layer is not sufficiently improved and the adhesion between each layer is not sufficient.

〔Effect of the invention〕

As detailed above, the multilayer molded article of the present invention has good impact resistance and barrier properties against gasoline and the like.

By limiting the resin in each layer as in the present invention, the polyolefin layer and the polyamide resin layer are well bonded via the modified polyolefin layer, and
This is thought to be because the impact resistance of the polyamide layer is improved and barrier properties are maintained.

Since the multilayer molded article of the present invention has the above-mentioned characteristics, it is suitable for various uses such as fuel tanks, automobile parts, and home appliance parts.

[Brief explanation of drawings]

FIG. 1 is a partial cross-sectional view showing an example of the layer structure of a multilayer molded product manufactured using the resin composition of the present invention. 1...Polyolefin layer 2...Polyamide resin layer 3...Modified polyolefin layer Applicant Tonen Petrochemical Co., Ltd.

Claims (4)

[Claims] (1) In a multilayer molded article in which a polyolefin layer and a polyamide resin layer are bonded together via a modified polyolefin layer, the polyolefin layer is made of crystalline polyolefin, and the polyamide resin layer is made of polyamide 51 to
80% by volume, and the content of unsaturated carboxylic acid or its anhydride is 1.0 x 10^-^5 to 6.0 x 10^-^5 mo
The modified polyolefin layer is made of the same crystalline polyolefin as the polyolefin layer modified with an unsaturated carboxylic acid or its anhydride. Multilayer molded body. (2) The multilayer molded article according to claim 1, wherein the crystalline polyolefin forming the polyolefin layer is polypropylene or high-density polyethylene. (3) In the multilayer molded article according to claim 1 or 2, the content of unsaturated carboxylic acid in the modified polyolefin is 2.0×10^-^6 to 2.0×10^-^4 mol/
A multilayer molded article characterized by g. (4) The multilayer molded article according to any one of claims 1 to 3, wherein the modified olefin elastomer has a tensile modulus of 0.07 to 3000 kg/cm^2.