JPS6350260B2 - - Google Patents

Description

[Detailed description of the invention]

<Industrial Application Field> The present invention relates to a multilayer hollow container with excellent chemical resistance and easy incineration properties. relates to a coextruded multilayer hollow container made of mineral-filled polyolefin. <Prior art> Conventionally, pesticides, fuel oils, and industrial chemicals (aromatic/aliphatic and hydrocarbon-based) have insufficient chemical resistance in hollow containers made of polyolefins such as polyethylene and polypropylene, which are widely used. The content of the container decreased during storage due to swelling, and cracks were likely to occur over time, making it unsuitable for use from a safety standpoint. For this reason, glass bottles and metal cans have generally been used as containers for organic chemicals. However, these containers have the problem of disposal after use, and there has been a strong desire for a container that can replace these containers. In recent years, we have developed multilayer hollow containers that have an inner layer of polyamide or saponified ethylene/vinyl acetate copolymer with excellent chemical resistance, an outer layer of inorganic-filled polyolefin with excellent burnability, and an adhesive resin as an intermediate layer. It is being put into practical use. As the above-mentioned hollow container, for example, JP-A-54-4681
It is shown in the publication No. The hollow container shown in Japanese Patent Application Laid-Open No. 54-4681 is
The outer layer is composed of a nonflammable inorganic material with reduced flash during molding, a polyolefin, a saponified ethylene-vinyl acetate copolymer, and a polyolefin modified with an unsaturated carboxylic acid or a derivative thereof. <Problems to be Solved> In blow molding, generally not all of the resin extruded into a parison becomes a molded container, and unnecessary resin called burrs or debris protrudes from the mold cavity. Even if this crusher burr is blended with new resin and used as recycled material immediately after crushing during single layer molding,
Since the resins are of the same type, the physical properties of the molded container do not change much. However, in multilayer molding, when a multilayer crusher burr is used in any layer, that layer has a blend composition of different resins, which tends to reduce dispersibility and deteriorate the physical properties of the molded product. In other words, in a three-layer container where the inner layer is polyamide or saponified ethylene-vinyl acetate copolymer, the middle layer is polyolefin modified with an unsaturated carboxylic acid or its derivative, and the outer layer is polyolefin, the outer layer is usually the thickest. Therefore, the recycled material is collected and blended into the inorganic-filled polyolefin for the exterior, but at this time, the outer layer becomes layered and does not have a completely uniform composition, so it is susceptible to external stress such as dropping and collision when it is removed from the mold. This causes delamination. As a result, the protective performance as a drug container is degraded, and in terms of appearance, only the peeled portion becomes white, resulting in a significant loss of commercial value. This peeling phenomenon in the outer layer is caused by poor dispersibility between the polyamide or saponified ethylene/vinyl acetate copolymer contained in the recycled material and the inorganic-filled polyolefin. The purpose of the present invention is to eliminate the peeling phenomenon that occurs due to the mixing of polyamide or saponified ethylene/vinyl acetate copolymer into polyolefin and inorganic filler, which originally have poor affinity. % of the crusher burr that is generated as recycled material in a closed system to reduce costs, and even if crusher burr is mixed in, it prevents peeling and whitening within the outer layer, and it is easily incinerated. It is an object of the present invention to provide a multilayer hollow container that does not impair its properties. <Means for Solving the Problems> The present invention has an inner layer made of polyamide or a saponified ethylene-vinyl acetate copolymer, an intermediate layer made of polyolefin modified with an unsaturated carboxylic acid or a derivative thereof, and an outer layer made of polyamide or saponified ethylene-vinyl acetate copolymer. In a multi-layer hollow container made of polyolefin containing 1% of non-flammable inorganic material, crusher burrs are added so that the outer layer contains 0.5 to 20% by weight of the resin constituting the inner layer, and the modified polyolefin used for the intermediate layer is The problem was solved by adding the same modified polyolefin in the range of 5 to 20 weight percent. In the present invention, nonflammable inorganic fillers include carbonate powders such as calcium carbonate and magnesium carbonate, kaolin clay powder, calcined clay powder, mica powder, mineral powders whose main component is silicic acid such as calcium silicate, and sulfuric acid. Sulfate powder such as barium and calcium sulfate, synthetic silicic acid such as white carbon,
Synthetic silicate powder, alumina hydrate powder such as bauxite, and oxide powder such as titanium oxide can be used. Alternatively, the above-mentioned inorganic powders can be used which have been surface-treated with various organic or inorganic substances for the purpose of improving various properties such as dispersibility in polyolefin and wetting. Further, these nonflammable inorganic fillers may be used alone, or two or more types may be mixed in any proportion. Inorganic filler powder and polyolefin pellets or powder generally have a low affinity, and a common single-screw extruder cannot produce an inorganic-filled polyolefin with good dispersion and mutual affinity. For this purpose, a mixture of an inorganic filler and a polyolefin, or a mixture of an inorganic filler and a polyolefin that have been surface-treated with various organic or inorganic substances as needed, is melt-mixed using a roll kneader, Banbury mixer, etc. to produce an inorganic-filled polyolefin. I am getting . Especially for inorganic-filled polyolefins used in blow molding, when the filling amount becomes high, the bending elastic modulus increases and the benefits of reducing burnt calories increase, but the impact strength decreases and the function as a container decreases. There is a limit to the amount of filling. The inorganic-filled polyolefin used in the present invention can have an inorganic filling amount of 10 to 60 wt%. However, considering the contradictory performance of moldability and low calorie combustion, the filling amount is 30 to 50wt%.
is appropriate. The polyolefin used in the present invention is a single resin such as low density polyethylene, high density polyethylene, polypropylene, or ethylene-propylene copolymer, or a combination of polypropylene with polyethylene, ethylene-propylene copolymer, or ethylene/ethylene acrylate copolymer. 5~ of any one type
This is a mixed resin containing 30wt%. <Function> The multilayer container obtained in the present invention, in which crusher burrs are collected in the nonflammable inorganic-filled polyolefin layer, has a nonflammable inorganic content of 10 to 60% by weight in the polyolefin of the outer layer, and 0.5 to 0.5% by weight of the inner layer resin.
Crusher to contain 20% by weight
In addition to adding flash, polyolefin modified with 5 to 20 weight percent of an unsaturated carboxylic acid or its derivative is added, so that the dispersion of polyamide or saponified ethylene-vinyl acetate copolymer and inorganic-filled polyolefin is The properties were improved, and there was no delamination within the outer layer. In addition, compared to multi-layer containers without crusher burrs, they exhibit almost the same physical properties in terms of drop strength, etc.
Furthermore, since the rigidity is improved, the decompression deformation resistance when storing chemicals etc. for a long period of time is increased. The present invention will be explained in more detail with reference to Examples below. <Example> All the containers shown in Table 1 are hollow molded containers consisting of three layers: an outer layer, an intermediate layer, and an inner layer, and the intermediate layer has a density of 0.94 and
The inner layer is made of modified polyethylene with a melt index of 0.4, the inner layer is polyamide with a relative viscosity of 4.5 and the density of 1.14, and the outer layer is made of high density polyethylene with a density of 0.94 and a melt index of 0.4 filled with 40% by weight of calcium carbonate with an average particle size of 1.5 microns. density
1.28, melt index 0.2, inorganic filled polyethylene mixed with modified polyethylene grafted with flash and unsaturated carboxylic acid in an appropriate ratio. In the table, x represents the inorganic filled polyethylene, y represents the flash, and z represents the weight percent of the modified polyethylene. As is clear from this table, in Comparative Example 1 in which burrs are not mixed into the outer layer, intralayer peeling of the outer layer due to falling does not occur, but burrs are
This can be seen in Comparative Example 2, which was mixed with a percentage of
Furthermore, in each of the examples in which modified polyethylene was mixed within a certain range, this problem was less likely to occur. In Comparative Example 3, in which 2% of modified polyethylene was mixed, this effect was not significant, and as seen in Examples 1 to 3, it is preferable to mix 5% or more of modified polyethylene. Furthermore, as the mixing ratio of modified polyethylene increases, the amount of calories burned increases, so the mixing ratio should be appropriately selected depending on the mixing ratio of burrs, etc.

[Table] <Effects of the invention> The present invention consists of the above structure, and the crusher
Problems caused by reduction of burrs, such as peeling of the nonflammable inorganic material and the resin and whitening phenomenon caused by simultaneous reduction of polyamide and saponified ethylene-vinyl acetate copolymer, can be solved by adding 5 to 20% by weight of modified polyolefin. By adding in a range of
This has the effect of preventing the peeling phenomenon with the saponified vinyl acetate copolymer and improving dispersibility, and can solve the problem of collecting crusher burrs in the outer layer, which occurs along with blow molding. You can use Kratshya Bali effectively,
It has become possible to manufacture containers that are easily incinerated, chemically resistant, and highly resistant to reduced pressure at a low cost.

Claims (1)

[Claims] 1. A multilayer hollow container whose inner layer is made of polyamide or saponified ethylene-vinyl acetate copolymer, whose middle layer is made of polyolefin modified with an unsaturated carboxylic acid or its derivative, and whose outer layer is made of polyolefin containing 10 to 60 percent by weight of a nonflammable inorganic material. In this step, a crusher burr is added so that the inner layer resin is contained in the outer layer in an amount of 0.5 to 20 weight percent, and the same modified polyolefin as the modified polyolefin used in the intermediate layer is added in a range of 5 to 20 weight percent. A multi-layer hollow container.