JPH0757542B2 - Multi-layer structure - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer structure having a resin composition layer in which the compatibility between a polyolefin and a saponified product of an ethylene-vinyl acetate copolymer is remarkably improved and a hue is also improved.

[0002]

2. Description of the Related Art A blend composition of a polyolefin and a saponified ethylene-vinyl acetate copolymer (hereinafter sometimes abbreviated as EVOH) has characteristic physical properties. Especially when multi-layer coextrusion molding of polyolefin and EVOH,
The interlayer adhesive force can be improved by using a layer of the blend composition instead of the polyolefin phase or the EVOH layer, or by providing a layer of the blend composition between the polyolefin and the EVOH layer. Although the characteristics of such a blend composition of polyolefin and EVOH have been known in the past, this composition generally has poor compatibility, and when a film, sheet, bottle, etc. is formed by extrusion molding, non-uniform phase separation occurs. It is known that foreign matter is liable to be generated, and particularly when the operation is performed for a long time (long run), the foreign matter is increased and the hue is deteriorated, and the appearance is significantly impaired. Thus, it was the actual situation that extrusion molding of a blend composition of polyolefin and EVOH could not be carried out practically at all, or even if it could, it could only be operated for a short time in many cases.

[0003]

SUMMARY OF THE INVENTION The present invention has been made to rename such poor compatibility and deterioration of hue and to improve long-run property, and to obtain a multilayer structure having a beautiful appearance. With the goal.

[0004]

Means for Solving the Problems The above object is to provide a resin composition layer in which a hydrotalcite compound (C) is contained in an appropriate amount in a polyolefin (A) and EVOH (B), and an EV.
This is accomplished by providing a multilayer structure having an OH or polyolefin layer.

The polyolefin (A) referred to in the present invention is
High-density, medium-density or low-density polyethylene, vinyl acetate, or polyethylene copolymerized with α-olefins such as butene, hexene, and 4-meter-1-pentene, polypropylene homopolymer, polypropylene graft-polymerized with ethylene, or Ethylene, butene,
It includes polypropylene copolymerized with α-olefins such as hexene and 4-methyl-1-pentene, modified polypropylene blended with a rubber polymer, poly-1-butene, poly-4-methyl-1-pentene, and the like. Of these, polypropylene resins are particularly poor in compatibility with EVOH, and are important in that the effects of the present invention are particularly remarkable.

Further, the saponified product of ethylene-vinyl acetate copolymer (EVOH) (B) referred to in the present invention is any as long as it hydrolyzes the vinyl acetate unit in the copolymer of ethylene and vinyl acetate. However, those having a poor compatibility with polyolefin have relatively few ethylene units and a high degree of saponification (hydrolysis) of vinyl acetate units. In particular, those having an ethylene unit content of 20 to 50 mol% and a vinyl acetate unit having a saponification degree of 96 mol% or more, particularly 99 mol% or more, have the highest gas barrier property against gases such as oxygen among thermoplastic resins. Is at a standard and
Since it is possible to obtain excellent containers by using it in combination with a polyolefin, it is particularly important as an application target of the present invention.

As the hydrotalcite compound (C) constituting the resin composition layer used in the present invention, a hydrotalcite compound which is a double salt represented by the following formula can be particularly mentioned.

[0008]

[Chemical 1]

Of these, the following are particularly preferable.

[0010]

[Chemical 2]

[0011]

[Chemical 3]

[0012]

[Chemical 4]

[0013]

[Chemical 5]

[0014]

[Chemical 6]

[0015]

[Chemical 7]

[0016]

[Chemical 8]

These hydrotalcite compounds are
Used alone or in admixture of two or more, it not only improves the compatibility between EVOH and polyolefin, but also improves the hue of the resulting molded article.

The amounts of the respective components of the polyolefin (A) and EVOH (B) constituting the resin composition of the present invention are not particularly limited and can be arbitrarily selected according to the purpose. However, from a practical point of view, polyolefin (A) and EVOH (B)
As for the composition ratio of (1), a composition having a large amount of either one of the resins is particularly important in that characteristic physical properties such as mechanical properties or gas barrier properties are exhibited. As a composition containing a large amount of polyolefin, the weight ratio of polyolefin (A): EVOH (B) is 80:20 to 99.9: 0.1, and especially 9
The range of 0:10 to 99.7: 0.3 is mentioned,
On the other hand, as a composition having a large amount of EVOH, the weight ratio of polyolefin (A): EVOH (B) is 5:95 to 3
It can be said that the range of 0:70 is particularly important in terms of the effect of the present invention.

Further, the addition amount of the hydrotalcite compound (C) for improving the compatibility depends on the mechanical properties of the composition,
It is adjusted within a range that does not impair various physical properties such as transparency and gas barrier property, but in many cases, the amount is 0. 0 with respect to 100 parts by weight of the total weight of the polyolefin (A) and EVOH (B) (A + B). 00001-10 parts, especially 0.000
Used in the range of 1 to 1 part. If it exceeds 10 parts, various physical properties other than compatibility are impaired, which is not preferable in many cases.

Further, when the component (C) is melt-blended with EVOH in advance, the use effect tends to be high.
In this case, 100 parts of EVOH and 0.002-0.5 parts of the component (C) are mixed. The effect of improving the compatibility in the melt molding of the composition obtained by adding 0.5 parts of this compound and 99.5 parts of polyolefin is remarkable. In this case, the amount of the component (C) is 0.00001 with respect to 100 parts by weight of the polyolefin and EVOH.
~ 0.0025 parts. The amount of component (C) is 0.000
If it is less than 01 parts, the effect is generally small.

Further, the component (C) is a polyolefin (A).
Alternatively, a part or all of EVOH (B) may be melt-blended in advance, and this may be blended with polyolefin (A) and / or
Alternatively, the above-mentioned component (A) blended with EVOH (B),
A method for obtaining a multilayer structure by coextrusion and melt-molding a composition comprising the components (B) and (C) and a saponified ethylene-vinyl acetate copolymer or a polyolefin is arbitrarily selected according to the purpose. In addition to the method in which the component (C) is previously melt-blended with EVOH as described above,
By combining a method in which the components are melt-blended in advance with the polyolefin or a method in which they are dry-blended, the long-run property is excellent and the compatibility improving effect can be remarkably obtained.

In the present invention, the mechanism by which the hydrotalcite compound (C) significantly improves the compatibility of the polyolefin and EVOH in melt molding is not clear. However, a titanium (Ti) compound contained in a polypropylene resin, which has a particularly poor compatibility with EVOH,
For example, if the residue of the Ti compound used as a catalyst during the polymerization is added to EVOH, the deterioration of EVOH is promoted. If the Ti compound and the compatibility improving compound shown in the present invention are added to EVOH at the same time, the deterioration of EVOH is prevented. It has been found by the present inventors to obtain. Thus
In a mixed system of polypropylene resin and EVOH, T
It can be presumed that the mechanism that the i compound acts on EVOH to cause remarkable incompatibility and the component (C) used in the present invention inhibits this action of the Ti compound. However, the mechanism described above is not necessarily general, and it is presumed that the rheological effect in the molten system of polyolefin and EVOH, the chemical action of impurities, etc. are complicatedly combined.

Other conventional additives may be added to the polyolefin for the resin composition of the present invention. Examples of such additives include antioxidants {2,5-di-t-butylhydroquinone, 2,6-di-t-butyl-p-cresol, 4,4'-thiobis- (6-t -Butylphenol), 2,2'-methylene-bis (4-methyl-6-t-butylphenol), octadecyl 3-
(3'5'-di-t-butyl-4'-hydroxyphenyl) propionate, 4,4'-thiobis- (6-t-
Butylphenol, etc.), ultraviolet absorber {ethyl-2-
Cyano-3,3-diphenyl acrylate, 2-
(2'-hydroxy-5-methylphenyl) benzotriazole, 2-hydroxy-4-octoxybenzophenone, etc.}, plasticizer (dimethyl phthalate, diethyl phthalate, wax, liquid paraffin, phosphate ester, etc.),
Antistatic agents (pentaerythrite monostearate, sorbitan monopalmitate, sulfated oleic acid, polyethylene oxide, carbowax, etc.), lubricants (ethylene bisstearamide, butyl stearate, calcium stearate, etc.), colorants (carbon Black, phthalocyanine, quinacridone, indoline, azo pigment, titanium oxide, red iron oxide, etc., filler (glass fiber,
Asbestos, mica, ballastonite, calcium silicate, aluminum silicate, calcium carbonate, etc.).
Also, many other polymer compounds can be blended to the extent that the effects of the present invention are not impaired.

The blending means of each component for obtaining the resin composition used in the present invention includes a ribbon blender,
Examples thereof include high speed mixers, cokneaders, pelletizers, mixing rolls, extruders and intensive mixers.

The resin composition used in the present invention, and E
VOH or polyolefin can be coextruded and melt-molded using a melt extruder to form any multilayer structure such as film, sheet, tube, bottle and the like. The extrusion temperature at the time of molding is appropriately selected depending on the properties of the extruder, the molecular weight of the resin, the compounding ratio, etc., but in many cases it is in the range of 170 ° C to 300 ° C. As described above, the resin composition used in the present invention exerts particularly remarkable characteristics when used as one layer of a multilayer structure, wherein the polyolefin layer is P, the EVOH layer is E, and the adhesive resin is When the layer is D and the layer of the resin composition used in the present invention is F, E / F / E, F / E, F / F
/ F, (F in the middle layer has a high content of EVOH), F / D
/ E, F / D / E / D / F, P / E / P / F, P / F /
When a layer structure such as D / E / D / F / P or P / F / D / E / D / P is adopted, a beautiful multilayer structure having a high interlayer adhesive force and good compatibility can be obtained. In particular, a multilayer structure including the layer F of the resin composition and the EVOH layer E used in the present invention is suitable from the viewpoint of gas barrier property. In such a multilayer structure, scraps of the multilayer structure can be used as the resin composition.

As a multi-layer molding method, generally, the number of extruders corresponding to the type of resin layer is used, and the flow of the molten resin in the extruder is co-extruded in a layered form, that is, so-called. Manufactured by coextrusion. Alternatively, a method of molding by extrusion coating may be adopted. Thus, the multilayer structure obtained by using the above resin composition has not only a uniform resin composition layer and a beautiful appearance, but also good compatibility and uniformity, and therefore, in terms of strength. Is also excellent,
Its industrial significance is great.

[0027]

EXAMPLES Hereinafter, the present invention will be described more specifically by way of examples.
The parts mean parts by weight.

Example 1 Isotactic polypropylene {Density (ASTM-
D-1505) 0.906 g / cm ³ , melt index (ASTM-D-1238) 0.8 g / 10 min, containing Ti compound as catalyst residue} (A), ethylene content 33 mol%, degree of saponification Of 99.9% and EVOH of 1.2 g / 10 minutes of the mettle index [0.05 wt% of hydrotalcite {Ca ₆ Al ₂ (OH) ₁₆ CO ₃ .4H ₂
O} melt-blended with EVOH and pelletized
H] and the same hydrotalcite weight ratio of 98/2 / 0.1 as described above were prepared by a Henschel type mixer at room temperature for 3 minutes. The mixture obtained by such an operation was pelletized by blending the extruder for the intermediate layer having a screw with a diameter of 40 mm and an effective length of 800 mm, and the EVOH (0.05 wt% hydrotalcite). EVOH) has a diameter of 6
The internal and external layer extruder was equipped with a screw having a length of 5 mm and an effective length of 1430 mm, and was equipped with an adapter having a melt channel that was branched into two.
Melt coextrusion is performed using a triple die for three layers at 0 ° C., and the outer layer and the inner layer are the EVOH, and the intermediate layer is a symmetrical three-layer type laminated structure of each blend by a known blow molding method. A rounded bottle (bottle) was molded.
As a result, even after continuous operation for 48 hours, a uniform and good bottle was obtained, the state of the film surface of the blended material layer was good, no phase-separated foreign matter due to poor compatibility was observed, and the film of the blended material layer was not observed. The hue of the surface was good and no yellowing was observed. Each of the obtained bottles had an outer layer: middle layer: inner layer thickness ratio of 4.5: 1: 4.5, an average wall thickness of about 600 μ, and an inner volume of about 280 cc.

Comparative Example 1 In the same manner as in Example 1 except that hydrotalcite was not used, a symmetric three-layer type laminated circular daub bottle was molded. As a result, about 3 hours after the start of operation, a large number of non-uniform phase-separated foreign matters, which were not found in Example 1, were generated, the number increased with time, and the appearance of the obtained bottle was extremely poor.

Comparative Example 2 In the same manner as in Example 1 except that calcium carbonate was used in place of hydrotalcite, a symmetrical three-layer type laminated circular daub bottle was molded. As a result, about 5 hours after the start of operation, a large number of non-uniform phase-separated foreign matters, which were not found in Example 1, were generated in the blended material layer, and the number increased with time. Further, yellowing was observed on the film surface of the blend, and the appearance of the obtained bottle was extremely poor.

Comparative Example 3 In the same manner as in Example 1 except that magnesium hydroxide hydrate was used in place of hydrotalcite, a double circular bottle having a symmetrical three-layer type laminated structure was prepared. Molded.
As a result, about 4 hours after the start of operation, a large number of non-uniform phase-separated foreign matters, which cannot be seen in Example 1, are generated in the blend layer,
The number increased over time. Further, yellowing was observed on the film surface of the blend, and the appearance of the obtained bottle was extremely poor.

Comparative Example 4 In the same manner as in Example 1 except that clay was used in place of hydrotalcite, a double circular bottle having a symmetrical three-layer type laminated structure was formed. As a result, about 4 hours after the start of operation, a large number of non-uniform phase-separated foreign matters that were not found in Example 1 were generated in the blended material layer, and the number increased over time. Further, yellowing was observed on the film surface of the blend, and the appearance of the obtained bottle was extremely poor.

Example 2 Isotactic polypropylene (PP) (A) used in Example 1, EVOH (B) used in Example 1,
The adhesive resin (maleic anhydride modified PP) (D) and the blend (F) prepared in Example 1 were charged into separate extruders, coextrusion was performed using a 4-kind 7-layer die, and a known hollow Depending on the molding method, PP (A) / blend (F)
/ Adhesive resin (D) / EVOH (B) / Adhesive resin (D) / Blend (F) / PP (A) (wall thickness ratio 12 /
6/1/2/1/6/12) Da-circular bottle (bottle) (average wall thickness: about 600μ, internal volume: about 280c)
c) was molded. As a result, similar to Example 1, a uniform and good bottle was obtained after continuous operation, and no phase-separated foreign matter due to poor compatibility was observed.

[0034]

EFFECT OF THE INVENTION The multilayer structure of the present invention has no phase-separated foreign matter due to incompatibility, has an excellent hue, and has a beautiful appearance.

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Claims (5)

[Claims] 1. A polyolefin (A), a saponified ethylene-vinyl acetate copolymer (B) and a hydrotalcite compound (C), wherein the component (C) is the resin (A) and (B). 0.0000 for 100 parts of total weight
Resin composition layer containing 1 to 10 parts and ethylene- vinyl acetate
A multilayer structure having a saponified copolymer or a polyolefin layer . 2. The multilayer structure according to claim 1, wherein the resin composition layer according to claim 1 is a layer containing scrap of the multilayer structure. 3. The multilayer structure according to claim 1, wherein the polyolefin (A) is a polypropylene resin. 4. The ethylene-vinyl acetate copolymer saponified product (B) has an ethylene unit content of 20 to 50 mol%,
The multilayer structure according to any one of claims 1 to 3, wherein the vinyl acetate unit has a saponification degree of 96% or more. 5. The weight ratio of polyolefin (A): ethylene-vinyl acetate copolymer saponification product (B) is 80: 20-9.
9.9: 0.1, The multilayer structure according to any one of claims 1 to 4.