JPH0289642A - Multilayer container - Google Patents

Abstract

PURPOSE:To lessen the loss in weight and adsorption swelling due to permeation of a water-containing organic solvent or the like and prevent cracks caused by the solvent or the like by using a composition of specific weight ratio composed of EVOH (A) and polyamide resin (B) as an innermost layer and making said layer substantially non-oriented in manufacturing a container. CONSTITUTION:An ethylene - vinyl acetate copolymer in a sponified material (EVOH) is of 20 - 60mol% of ethylene content and 90% or more of saponification degree. For polyamide resin, the mol ratio (CH2/NHCO) of CH2 and NHCO in polyamide should preferably be in the range of 5.5 - 10. The bending ratio of EVOH (A) and polyamide (B) is B/A = 5/95 - 95/5. Said blended composition of EVOH and polyamide is used for an innermost layer of a container, and a main body constituting the container should at least be non-oriented substantially, and also corner sections and shoulder sections of the container should preferably be non-oriented substantially.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Industrial Field of Application The present invention is mainly aimed at plastic containers filled with contents containing organic solvents or water-containing organic solvents, which have little weight loss due to permeation of organic solvents or water-containing organic solvents. The present invention relates to a plastic multilayer container that not only has excellent barrier properties but also has less container cracking (stress cracks and bag breakage due to organic solvents).

B. Conventional technology High-density polyethylene (HDPE) single-layer bottles have been used as plastic containers for contents containing organic solvents or water-containing organic solvents, such as agricultural chemicals. The problem was that the swelling and permeation were large, resulting in not only a loss of content but also deterioration of the content due to changes in solvent concentration and composition. Therefore, a gas-resistant resin such as polyamide (FA) or ethylene-vinyl alcohol copolymer (EV
Methods have been taken to blend or layer OH). However, for PA, swelling, elution, and permeation due to organic solvents or water-containing organic solvents are EVO)
Its use is limited because it is inferior to I. On the other hand, E V 0
By providing at least one layer in the innermost layer of λ, the swelling, elution, and permeation can be greatly suppressed.Currently,
There are many on the market. However, when EVOH is used, the EVOH layer may crack or break due to the solvent (
There are problems such as stress cracks) or a decrease in drop strength. Especially EVOHFi! This phenomenon becomes more pronounced as the thickness of the EVOHF! The problem is that it is not possible to make the container thicker, or it is not possible to make a large container.

By the way, there are various examples of using compositions in which various nylons are blended with E V OH' for containers, etc. (
52-73966, 52-141735, 50-121347), these are Ol or C that focuses on imparting stretchability or adhesion during container molding.
This patent relates to gas barrier containers for food packaging such as O2, and focuses on improving gas barrier properties by using gas barrier eyebrows as an intermediate layer, and as shown in the present invention, containers filled with organic solvents. There is no disclosure of any technical idea that the effect of improving the drop bag tearing property when dropped, much less the stress cracking property is remarkable, and these effects cannot be achieved with EVOH or polyamide alone, but by blending them. There is no disclosure of the scales played.

The present invention is mainly intended for plastic containers filled with contents containing organic solvents or hydrous organic solvents. The purpose of the present invention is to provide a plastic multilayer container with less chance of bag breakage due to falling.

D. To solve the problem, the inventors used EV OH (A) and polyamide resin (B
), weight ratio (B)/(A)-5/95 to 951
It has been found that a container in which the composition No. 5 is used as the innermost layer and the core layer is substantially unoriented solves the above problems.

E. Detailed Description The saponified ethylene-vinyl acetate copolymer (EVOH) used in the present invention has an ethylene content of 20 to 60 mol%.
, with a saponification degree of 90% or more. If the ethylene content is less than 20 mol%, the melt colorability will be poor, while if it is 60 mol% or more, the gas barrier properties will be insufficient. Further, if the degree of saponification is less than 90 mol%, barrier properties and thermal stability are poor and it cannot be used. In addition, the EVOH may be copolymerized with butylene, propylene, vinylsilane compounds, vinylpyrrolidone compounds, plasticizers, heat stabilizers, ultraviolet absorbers, antioxidants, colorants, etc. within a range that does not impede the effects of the present invention. You are free to blend agents, fillers, etc. 0 As the polyamide resin of the present invention, nylon 6, nylon 6.
Nylon 6 resins such as nylon 6, nylon 6.9, nylon 6.12, nylon 11, nylon 12 and their elastomers, aromatic polyamides, and blends of these can be used, but The molar ratio of C11 groups to N II CO groups (CI, groups/NlIC0 groups) in the polyamide is preferably in the range of 5.5 to 1O. When the CH, group/NHCO group is less than 55, gel is likely to be generated by blending with EVOH, and bag breakage is likely to occur. On the other hand, if it exceeds 1O, the drop resistance and stress crack resistance will decrease. More preferably, 55≦C1+, group/NlIC0≧
9, more preferably 6.0≦Ctt, group/l1tlCO
Group≦8.

The blend ratio of EVOH (human) and polyamide (B) is B/A = 5/95 to 9515. B/
If A = less than 5795, the improvement effect will be small; on the other hand, if 9
When it exceeds 515, the weight loss due to solvent permeation increases. Preferably B/A = 5/95 to 80/20, optimally B/A = 10/95 to 7'0/30.

The method of blending EVOH and polyamide is not particularly limited, and a method of tri-blending, more preferably a method of charging the resin into a Banbury mixer-screw or twin-screw extruder to form pellets. can give. At this time, plasticizers, heat stabilizers, ultraviolet absorbers,
Colorants, fillers, etc. may be added as long as they do not interfere with the present invention.

The EV OH and polyamide blend composition thus obtained is used as the innermost layer of the container. The layer structure of the container is blend layer/Ad layer/TP,'? J, blend layer/AdF! /blend FJ/Adm/Tp layer, blend a/p, dPA/blend layer, blend layer/Ad
Examples include layer/EV OH layer/ad layer/TP layer. Here, Ad means adhesive resin, such as polyolefin resin (polyethylene, polypropylene,
Examples include ethylene-vinyl acetate copolymers, ethylene-acrylic esters (methyl or ethyl), etc.) modified with unsaturated carboxylic acids such as machiic anhydride. Further, TP means a plastic resin, such as polyolefin (polypropylene, polyethylene (high density, low density)), polyvinyl chloride, polyester, polyamide, etc. Among these, polyolefins, particularly high density polyethylene (HDPE), are preferred. As for the layer structure, it is essential to provide a blend layer of EVOH and polyamide as the innermost layer, but it is more effective to provide one or more blend layers. In particular, when the total thickness of the blend layers is the same, splitting the blend layer into two or more layers will greatly improve drop bag breakage resistance and stress cracking resistance, rather than using a single blend layer.

In that case, it is optimal to provide the blend layer as the intermediate layer and/or the outermost layer. Also, the EVOH layer can be used as an intermediate layer and/or
Alternatively, it is also a preferable embodiment to provide it in the outermost layer. Further, although it is preferable to provide an adhesive resin (Ad) layer, it is not particularly necessary to provide it if the blend layer and the thermoplastic resin (TP) layer are temporarily bonded.

In the present invention, it is important that the innermost layer of EVOH and polyamide is substantially unoriented. Here, "substantially unoriented" means that the main body of the container is at least substantially unoriented, including a portion of the corner of the container,
The shoulders are also preferably substantially unoriented, but may be somewhat oriented. Whether or not the crystal is unoriented can be determined by measuring the degree of orientation of the crystal in each direction using an X-ray photograph, double bending, or the like.

For example, if you take an X-ray diffraction photograph of a film by changing the incident direction of X-rays and obtain a dotted, arcuate, or annular diffraction image (Debye ring) with uneven intensity distribution, the film is oriented. If a diffraction image that does not reflect this is obtained, it can be determined that the material is substantially unoriented.

In addition, the birefringence (Δn) of the cross section of the film is measured using a birefringence measuring microscope, etc., and Δn = 0.0, depending on the measurement accuracy.
If it is 005 or less, it can be determined that it is substantially unoriented.

It is preferable that the layers other than the innermost layer constituting the container are also substantially unoriented, but this is not necessarily the case. Alternatively, the molten parison or sort obtained by co-injection is directly blown (direct blow) or vacuum or pressure molded, or the parison or sort obtained by co-extrusion or co-injection is once cooled and then molten. Obtained by blowing or vacuum or pressure forming.

In the present invention, the fact that the container is not oriented may be due to the fact that the residual stress generated during blow molding is smaller than that of a container that has been stretched and oriented. It has the advantage of being highly effective in reducing or improving the drop strength over time caused by this. The thickness of the obtained container, especially the body body, is such that the thickness of the blend layer (if there are multiple blend layers, the total thickness) is 5 to 300μ, preferably 10 to 200μ, and the thickness of the whole body is 5 to 300μ, preferably 10 to 200μ. The thickness is 100~
3000μ, and 400 to 2000μ for one child.

The container of the present invention is suitable as a container for filling an organic solvent or a water-containing organic solvent, particularly an agricultural chemical. Examples of organic solvents and agricultural chemicals include nonpolar liquids such as nclohexane, kiln, and toluene, polar liquids such as ethyl acetate, tetrahydrofuran, and dimedylformamide, and DDV.
Examples of agrochemical liquids include P emulsion, Nisdox emulsion, Hinozan emulsion, Lonestar emulsion, Ersan emulsion, EPN emulsion, and Dyori-Non emulsion.

The present invention will be explained in more detail below with reference to Examples, but the present invention is not limited thereto.

F Examples Examples 1 to 4 E V After triblending OH and polyamide, -
Pellets were created using a axial extruder (200°C).

This pellet was dried at 105°C for 16 hours. A bottle (bottle volume: 500 m12) having the thickness structure of the bottle body as shown in Table 1 was obtained from the pellets using a three-type, three-layer coextrusion direct blow molding machine (Guy temperature: 230° C.). The birefringence of each layer of the body of this bottle was measured, and Table 1
Both layers were substantially unoriented. Agrochemicals (DDVP type) were placed in this container, left at 5° C. for one day, and then a drop test (1 m height) was conducted. 100 again
After standing for several days, the appearance and weight loss of the pesticide in the bottle were observed and measured. The results are shown in Table 1.

In addition, in order to measure the basic properties, a blend composition of EVOH and polyamide was extruded at 400/l using a 25 mmφ-shaft single layer extruder.
63.5x12.5x by injection molding machine
A molded article of 6.5 m/m was obtained. The injection molded product was notched and tested for impact strength (kg
Jcm/cm), and 400μ sheet is 12.5
The sample was cut to 30mm x 30mm, placed in a 12mm medium holder and sorted into n-type, and immersed in agricultural chemicals (40°C), after which the time until cracks appeared was measured.

Of course, the container of the present invention loses less weight due to permeation of organic solvents,
There is also less cracking caused by organic solvents.

Claims (2)

[Claims] (1) Consisting of a saponified ethylene-vinyl acetate copolymer (A) with an ethylene content of 200 to 60 mol% and a degree of saponification of the vinyl acetate component of 90% or more, and a polyamide resin (B),
A multilayer container, the innermost layer being a layer of a composition whose weight ratio (B)/(A) is 5/95 to 95/5, and the layer is substantially unoriented. (2) The multilayer container for agricultural chemicals according to claim 1.