JPH01238933A - Multilayer vessel - Google Patents

Abstract

PURPOSE:To obtain a multilayer vessel having preferable adhesive properties by forming outer and inner layers of specific modified polyolefin and an intermediate layer of modified polyamide in which polyamide and specific modified polyolefin are mixed. CONSTITUTION:Modified polyolefin to be used is of polyolefin grafted from at least one type selected from unsaturated carboxylic acid and its derivatives, the graft ratio of the modified polyolefin used for the inner and outer layers is ranged in 0.005-0.5wt.%, and the graft ratio of the modified polyolefin used for the intermediate layer is ranged in 0.01-1.0wt.%. The modified polyamide is formed by mixing the polyamide and the modified polyolefin in such a manner that the mixing ratio is 50-90wt.% of the polyamide and 4-50wt.% of the modified polyolefin. As a method of mixing the polyamide and the modified polyolefin, a melt blending using a mixer such as an extruder, a kneader, a Banbury mixer, is preferably employed at the point of uniformity, and as a method of molding a multilayer vessel, a coextrusion hollow molding method is preferably employed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a multilayer container with excellent impact resistance and solvent permeation resistance.

[Conventional technology]

Conventionally, containers for solvents and the like have generally been made of metal or glass, but in recent years, containers made of plastic have come into use. Plastic containers have various advantages, such as being lightweight, having excellent impact resistance, not requiring treatment such as rust prevention, and having a high degree of freedom in design. Polyolefin is suitable as a plastic that meets these characteristics, and is used for various industrial chemical containers,
It is used in various fields such as kerosene cans, drums, and gasoline tanks. However, one drawback of polyolefin containers is that they have poor solvent permeation resistance. In order to improve this drawback, a multilayer container using a barrier resin such as polyamide is considered. However, since polyamide has no affinity with polyolefin, a container exhibiting good adhesiveness cannot be obtained unless an adhesive layer is interposed between the two layers when multilayering. Furthermore, in the case of containers for solvents such as alcohol, polyamide cannot be used for the inner layer because it swells. Furthermore, in the case of containers where impact resistance is particularly important, it is difficult to use it for the outer layer.

Therefore, polyamide is usually positioned as an intermediate layer, but
In this case, the container must have a complicated structure consisting of 5 m of three types: polyolefin/adhesive/polyamide/adhesive/polyolefin. The three-type, five-layer method requires at least three extruders and a complicated die structure, making it extremely complicated in terms of equipment and manufacturing.

(Problems to be Solved by the Invention) It is an object of the present invention to provide a multilayer container that has good adhesive properties even without an intervening adhesive layer, unlike such conventional containers.

[Means to solve the problem]

In view of the above-mentioned current situation, the inventors of the present invention have made extensive studies and have found a multilayer container with a two-layer, three-layer structure that does not require an adhesive layer, and have completed the present invention.

That is, in the present invention, the outer layer and the inner layer are grafted with at least one compound selected from unsaturated carboxylic acids or derivatives thereof, and the grafting ratio is 0.005 to 0.5 wt.
%, the intermediate layer is grafted with 50 to 95 wt % polyamide and at least one compound selected from unsaturated carboxylic acids or derivatives thereof, and the grafting ratio is o, oi to 1.0 wt %. The present invention relates to a multilayer container made of modified polyamide mixed with 5 to 50 wt% of polyolefin.

The polyolefin used in the present invention refers to at least one of high-density polyethylene, low-density polyethylene, linear low-density polyethylene, ethylene-vinyl acetate copolymer, polypropylene, and the like. Among these polyolefins, high-density polyethylene (hereinafter abbreviated as HDPE) is preferred in terms of moldability, strength, and impact resistance.

The modified polyolefin used in the present invention refers to a polyolefin grafted with at least one monomer selected from unsaturated carboxylic acids or derivatives thereof.

Specific examples of unsaturated carboxylic acids include acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, etc., and derivatives of unsaturated carboxylic acids include:
Acid anhydrides, esters, amides, imides, metal salts, etc., such as maleic anhydride, citraconic anhydride, itaconic anhydride, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, methacrylic acid Butyl, glycidyl acrylate, glycidyl methacrylate, monoethyl maleate, diethylnisder maleate, fumarushun monomethyl ester,
Fumaric acid dimethyl ester, itaconic acid monoethyl ester, itaconic acid diethyl ester, acrylamide,
Methacrylamide, maleic monoamide, maleic diamide, maleic 1-N-monoethylamide, maleic 1-N,N-diethylamide, maleic 1-N-monoethylamide, maleic MN, N-dibutylamide.

fumaric acid amide, fumaric acid diamide, fumaric acid-N-monoethylamide, fumaric acid 1-N, N-diethylamide,
fumar 1-N-monobutyramide, fumar 1-N, N-
dibutylamide, maleimide, N-butylmaleimide,
Examples include N-phenylmaleimide, sodium acrylate, sodium methacrylate, potassium acrylate, potassium methacrylate, and the like. Among these, maleic anhydride is most preferred.

Methods of grafting these monomers onto polyolefins include mixing polyolefins, monomers, and radical generators such as peroxides, and grafting them by melt extrusion, or grafting onto polyolefins suspended or dissolved in a suitable solvent. Examples include a method in which grafting is carried out by adding a nitrate and a radical initiator and heating.

The grafting rate of the modified polyolefin used in the inner layer and outer layer is 0.005 to 0.5 wt%, preferably o, oi to
It is in the range of 0.1 wt%. If it is less than 0.005 wt%, the adhesiveness will be insufficient, and if it exceeds 0.5 wt%, the cost will increase, which is not preferable. In addition, the grafting rate of the modified polyolefin used in the intermediate layer is 0.01 to 1.0 w.
t%, preferably within the range of 0.05 to 0.5 wt%. If it is less than 0.01 wt%, the compatibility with the polyamide is insufficient, and if it exceeds 1.0 wt%, although the compatibility with the polyamide is sufficient, it increases the cost, which is not preferable. In addition, the melt flow rate (measured according to JIS K 7210 at a temperature of 1906C and a load of 2.16 kg, hereinafter abbreviated as MFR) of the modified polyolefin used for the inner and outer layers is 0.01 to 10.0 g/1.
0 m1n is preferable, 0.02 to 3.09/10 m1n
I like it a lot. If it is less than 0.019710m, the fluidity during melting may deteriorate;
/10m1n, the drawdown property increases,
It may become difficult to mold. On the other hand, the VFR after grafting of the modified polyolefin used in the intermediate layer is
0.01~io,og/10m1n is preferable, and 0.01~io,og/10mln is preferable.
02 to 5.09/10 m1n is roughly preferred. 0.0
If it is less than 1 g/10+nin, the fluidity during melting may deteriorate, and if it exceeds 10.0 g/10 m1n, dispersion may necessarily be reduced during kneading with modified polyamide.

The polyamide used in the present invention is a linear synthetic polymer having an acid amide bond -CONH-, including nylon-6, nylon-6,6, nylon-6, 10, nylon-11, nylon-12, and the like. It may also be a blend or copolymer. Among these nylons, nylon-6 is preferred in terms of moldability and strength.

The modified polyamide in the present invention refers to a mixture of the above-mentioned polyamide and modified polyolefin, and the mixing ratio of polyamide and modified polyolefin is as follows:
The content ranges from 0 to 95 wt%, and from 5 to 50 wt% of the modified polyolefin. If the proportion of the modified polyolefin is less than 5 wt%, interlayer adhesion will decrease, and if it exceeds 50 wt%, solvent permeation resistance will decrease, which is not preferable.

MFR (JIS
According to K 7210, temperature 230'C, load 2.16
Measured in kg. ) is 0.01 to 5.0 g/1
0 m1n is preferred. If it is less than 0.01 g/10 m1n, the fluidity during melting may be poor;
/10m1n may result in poor workability.

Methods for mixing polyamide and modified polyolefin include tri-blending using a conical blender or ■blender, or melt blending using a mixer such as an extruder, kneader, or Banbury. Blends are preferred.

Any method may be used to mold the multilayer container using these resins, but coextrusion blow molding is preferred. Examples of the method include an extrusion method and a single accumulator method. For large containers, a single accumulator method is suitable, and for small containers, an extrusion method is suitable. The molding conditions are a resin temperature of 220 to 230'C for the modified polyolefin used for the outer and inner layers.
1 The resin temperature of the modified polyamide used for the intermediate layer is 230~
Preferably, the temperature is set to 250°C.

In this way, it is possible to obtain a multilayer container with good impact resistance and solvent permeation resistance, which is composed of two types and three layers.

(Example) Next, examples of the present invention and comparative examples corresponding thereto will be described, but the present invention is not limited to these.

Example 1 Accumulator type blow molding machine (90mm diameter).

30sφ) was used for molding.

MF by grafting 0.02wt% maleic anhydride onto HDPE (Poronhard 8600A, manufactured by Tosoh Corporation)
A modified polyolefin having an R of o and o3h/10m1n was supplied from an extrusion tl (90sφ) for inner and outer layers to a multilayer die. On the other hand, the modified polyamide used for the intermediate layer is nylon-6 (1030B, manufactured by Ube Industries, Ltd.) and MFR
658 in a ratio of 6:4 of 0.35 g/10 m1n HDPE, Poron Hard 8300A (manufactured by Tosoh Corporation) and 0.2 wt% maleic anhydride.
Melt mixing was performed separately by φ extrusion. M obtained in this way
A modified polyamide having an FR of 0.35 g/10 m1n was supplied from an extruder for intermediate layer (30 sφ) to a die for multilayer. The molding temperature was set such that the resin temperature was 230° C. for the modified polyolefin for the inner and outer layers, and 240° C. for the polyamide for the intermediate layer, and multilayer blow molding was performed.

The multilayer container obtained as described above had three layers of two types and had a thickness of 2 m for the outer layer, 0.1 m for the middle layer, and 2 layers for the inner layer. The multilayer container was a 40 liter cylindrical plastic drum.

The interlayer adhesive strength, low temperature drop strength, and gasoline permeability of the obtained plastic drum were measured and the results are shown in Table 1. Here, interlayer adhesion strength (unit, Kg/10m
m) is a test piece with a width of 10s++ and a length of 120M at a peeling speed of 200#/m! T of n! Measured by IJ separation. Low temperature drop strength (unit, number of non-destructive samples (f[1il
)/Number of samples (pieces) is the number of samples obtained by adding 100% 50% ethylene glycol aqueous solution, leaving it in a low temperature room at -40°C for 24 hours, and then dropping it from a height of 10 m, and the number of non-destructive samples. Ta. Gasoline permeability (unit, y
/day), a plastic drum was filled with 50% Ganrin and aged at 40'C for 30 days, and then the gasoline permeability was measured.

Example 2 Nylon-6 (1030B, manufactured by Ube Industries, Ltd.) and HDP with MFR of 0.35 g/10 m1n as the intermediate layer
E was mixed with Poron Hard 8300A (manufactured by Tosoh Corporation) with 0.2 wt% maleic anhydride grafted at a ratio of 7:3.
Melt and mix in a 65Nnφ extruder at a ratio of 0.
Multilayer blow molding was carried out in the same manner as in Example 1 except that 40 g/10 m1n of modified polyamide was used.

Example 3 Nylon-6 (1030B, manufactured by Ube Industries, Ltd.) and HDPE with an MFR of 0.35 g/10 m1n as an intermediate layer
8:2 with Poron Hard 8300A (manufactured by Tosoh Corporation) and 0.2 wt% maleic anhydride.
(at a ratio of 65Mφ extruder) are mixed by various companies and the MFR is 0.
Multilayer blow molding was carried out in the same manner as in Example 1 except that 45 g/10 m1 of modified boron 1,17 amide was used.

Example 4 Poronhard 8300AA in HDPE for outer and inner layers
, manufactured by Tosoh Corporation> with maleic anhydride.
%grafted M F Rtfio, 03g/10m1
Multilayer blow molding was carried out in the same manner as in Example 1 except that n modified polyolefin was used.

Comparative Example 1 A multilayer hollow was fabricated in exactly the same manner as in Example 1, except that instead of the modified polyolefin used for the outer and inner layers, unmodified HDPE with an MFR of 0.03 g/10 m1n and Poronhard 8300A (manufactured by Tosoh Corporation) were used. I did the molding.

Comparative Example 2 Multilayer blow molding was performed in exactly the same manner as in Example 1, except that only unmodified nylon-6 (1030B, manufactured by Ube Industries, Ltd.) was used instead of the modified polyamide used for the intermediate layer.

Comparative Example 3 In Example 1, nylon-6 (1030B) was used as the intermediate layer.
(manufactured by Ube Industries, Ltd.) and MFR is 0.35 g/1
A modified polyamide with an MFR of 0.25 g/10 m1 was obtained by melt-mixing 0 m1n of HDPE with 0.2 wt% maleic anhydride grafted onto Poron Hard 8300A (manufactured by Tosoh Corporation) in a ratio of 4:6 using a 65sφ extruder. Multilayer blow molding was carried out in exactly the same manner except that .

(Effects of the Invention) As is clear from the above description, according to the present invention, even without using an adhesive layer, interlayer adhesion is good, impact resistance,
A multilayer container with excellent solvent permeation resistance can be obtained. In addition, since no adhesive layer is required, only two extrusions are required, and the die structure can be simpler than the three-layer, five-layer method, reducing equipment and processing variable costs. Can be done.

Claims (1)

[Claims] (1) The outer layer and the inner layer are made of modified polyolefin grafted with at least one kind of compound selected from unsaturated carboxylic acids or derivatives thereof and the grafting rate is 0.005 to 0.5 wt%, and the middle layer is made of polyamide 50 to 0.5 wt%.
95 wt% and 5 to 50 wt% of a modified polyolefin grafted with at least one kind of compound selected from unsaturated carboxylic acids or derivatives thereof and having a grafting rate of 0.01 to 1.0 wt%. A multilayer container featuring