JPH09104784A - Compatibilizing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a molded product remarkably improved in the compatibility of a polyolefin with a saponified product of an ethylene/vinyl acetate copolymer and excellent in appearance, hue, etc., by using as a compatibility improver a hydrotalcite compound. SOLUTION: (A) A polyolefin (e.g. a polypropylene resin) and (B) a saponified product of an ethylene/vinyl acetate copolymer are compatibilized using (C) a hydrotalcite. Preferably the component (C) is particularly a double salt represented by the formula I (M denotes Mg, Ca, or Zn, A denotes CO3 or HPO4 , and (x), (y), (z), and (a) are each a positive number and specific examples are compounds represented by formulae II and III. The component (B) is a saponified product of an ethylene/vinyl chloride copolymer wherein the content of the ethylene units is 20 to 50mol% and the degree of saponification of the vinyl acetate units is at least 96%, which is a particularly important component in this compatibilizing method because the use of the combination of this component with the component (A) gives excellent containers high in gas barrier properties.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compatibilizing method in which the compatibility between a polyolefin and a saponified ethylene-vinyl acetate copolymer is remarkably 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. In particular, during multi-layer coextrusion molding of polyolefin and EVOH,
The interlayer adhesion can be improved by using a layer of the blend composition instead of the polyolefin layer or the EVOH layer, or by providing a layer of the blend composition between the polyolefin and the EVOH layer. The characteristics of such a polyolefin / EVOH blend composition have been known in the past, but this composition generally has poor compatibility, and when formed into a film, sheet, bottle, etc. by extrusion, non-uniform phase separation occurs. It is known that foreign matter is likely to be generated, and in particular, due to long-term operation (long run), the foreign matter increases, the hue is deteriorated, and the appearance is significantly impaired. Thus, in many cases, extrusion molding of a blend composition of polyolefin and EVOH cannot be practically performed at all, or can be performed only for a short period of time in many cases.

[0003]

SUMMARY OF THE INVENTION The present invention has been made to eliminate such deterioration of compatibility and hue and to improve long-run property, and it is an object of the present invention to obtain a molded article having a beautiful appearance. And

[0004]

The above object has been achieved by providing a method for compatibilizing a polyolefin (A) and an EVOH (B), characterized by using a hydrotalcite compound (C). Is done.

The polyolefin (A) referred to in the present invention is:
High-density, medium-density or low-density polyethylene, vinyl acetate, acrylate, or polyethylene copolymerized with α-olefins such as butene, hexene, 4-methyl-1-pentene, ionomer resin, polypropylene homopolymer, ethylene Polypropylene, or ethylene, butene, hexene,
It includes polypropylene copolymerized with α-olefins such as 4-methyl-1-pentene, modified polypropylene blended with a rubber-based polymer, poly 1-butene, poly 4-methyl-1-pentene, and the like. Among these, polypropylene-based resin is important in that compatibility with EVOH is particularly poor, and the effect of the present invention is particularly remarkable.

[0006] The saponified ethylene-vinyl acetate copolymer (EVOH) (B) referred to in the present invention may be any one obtained by hydrolyzing a vinyl acetate unit in a copolymer of ethylene and vinyl acetate. However, those having poor compatibility with polyolefin have relatively few ethylene units and high saponification degree (hydrolysis degree) 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 properties against gases such as oxygen among thermoplastic resins. At the level and
It is particularly important as an application object of the present invention because excellent containers can be obtained by using it in combination with polyolefin.

Further, as the hydrotalcite compound (C) used in the present invention, there may be particularly mentioned a hydrotalcite compound which is a double salt represented by the following formula.

[0008]

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Among these, the following are exemplified as particularly preferable ones.

[0010]

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[0011]

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[0012]

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[0013]

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[0014]

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[0015]

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[0016]

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

The amounts of the components of the polyolefin (A) and the EVOH (B) used in the present invention are not particularly limited, and can be arbitrarily selected according to the purpose. However, from a practical point of view, the composition ratio of the polyolefin (A) and the EVOH (B) is such that a composition in which the amount of either resin is large exhibits characteristic properties such as mechanical properties or gas barrier properties. Of particular importance. As a composition containing a large amount of polyolefin, the weight ratio of polyolefin (A) to EVOH (B) is preferably 80:20 to 99.9: 0.1, particularly 90: 1.
0 to 99.7: 0.3, while E
As a composition having a large amount of VOH, polyolefin (A): EV
It can be said that a weight ratio of OH (B) in the range of 5:95 to 30:70 is particularly important in terms of the effects of the present invention.

The amount of the hydrotalcite-based compound (C) for improving compatibility is determined by adjusting the mechanical properties of the composition,
It is adjusted within a range that does not impair various properties such as transparency and gas barrier properties. In many cases, the amount is adjusted to polyolefin (A).
0.00001 to 10 parts, especially 0.0001 to 1 with respect to 100 parts (A + B) of the sum of the weight of
Used in the range of parts. If it exceeds 10 parts, various physical properties other than compatibility are impaired, and it is often unfavorable.

When the component (C) is previously melt-blended with EVOH, the use effect tends to be high.
In this case, for example, a mixture of 0.002 to 0.5 part of the component (C) in 100 parts of EVOH is exemplified. The effect of improving the compatibility in melt molding of a composition containing 0.5 part of this compound and 99.5 parts of polyolefin is remarkable. In this case, the amount of the component (C) is 0.00001 per 100 parts of the sum of the weights of the polyolefin and the EVOH.
It becomes 0.0025 part. The amount of the component (C) is 0.000
When the amount is less than 01 parts, the effect is generally small.

Further, the component (C) is a polyolefin (A)
Alternatively, a part or all of the EVOH (B) is previously melt-blended, and this is mixed with the polyolefin (A) and / or
Alternatively, a method of blending with the EVOH (B) and melt-molding to obtain a molded product comprising the components (A), (B) and (C) is arbitrarily selected depending on the purpose. As described above, in addition to the method in which the component (C) is previously melt-blended with EVOH, the method in which the component (C) is melt-blended in advance with a polyolefin, or a combination of these methods with a method of dry blending. Thereby, excellent long-run property can be obtained, and a remarkable effect of improving compatibility can be obtained. This is apparent from Example 4 described later. The method of dry blending each of the components (A), (B) and (C) and melt-molding the same can also be adopted. However, the component (C) is previously melt-blended with the component (A) or (B). This method is preferable from the viewpoint of long run.

In the present invention, the mechanism by which the hydrotalcite-based compound (C) remarkably improves the compatibility in melt molding of polyolefin and EVOH is not sufficiently clear. However, a titanium (Ti) compound contained in a polypropylene resin which is particularly incompatible with EVOH,
For example, when a Ti compound, which is a residue of a polymerization catalyst, is added to EVOH, alteration of the EVOH is promoted, and the Ti compound and the compatibility improving compound shown in the present invention are simultaneously added to the EVO.
It has been found by the present inventors that the addition of H can prevent the deterioration of EVOH. Thus, in the mixed system of polypropylene resin and EVOH, the Ti compound is
A mechanism can be presumed that it acts on VOH, causing significant poor compatibility, 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 the rheological effects in a molten system of polyolefin and EVOH,
It is presumed that the chemical actions of impurities and the like are intricately combined.

In the present invention, other conventional additives can be blended with the polyolefin. 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., and an ultraviolet absorber {ethyl-2-cyano-3,3-diphenylacrylate , 2- (2'-hydroxy-5-methylphenyl) benzotriazole, 2
-Hydroxy-4-octoxybenzophenone, etc., plasticizers (dimethyl phthalate, diethyl phthalate, wax, liquid paraffin, phosphate ester, etc.), antistatic agents (pentaerythritol monostearate, sorbitan monopalmitate, sulfuric acid) Oleic acid, polyethylene oxide, carbowax, etc.), lubricants (ethylene bis stearamide, butyl stearate, calcium stearate, etc.), coloring agents (carbon black, phthalocyanine,
Quinacridone, indoline, azo pigments, titanium oxide,
Bengara) and fillers (glass fiber, asbestos, mica, ballastonite, calcium silicate, aluminum silicate, calcium carbonate, etc.). Many other high molecular compounds can also be blended to such an extent that the effects of the present invention are not impaired.

Examples of the compatibilizing means of the present invention include a ribbon blender, a high-speed mixer co-kneader, a pelletizer, a mixing roll, an extruder, and an intensive mixer.

The resin composition of the present invention can be formed into an arbitrary molded product such as a film, a sheet, a tube, a bottle and the like by using a well-known melt extrusion molding machine. 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, and the like.
It is in the range of 300 ° C. As described above, when the resin composition of the present invention is used as one layer of a multilayer material, particularly remarkable features are exhibited. The polyolefin layer is P, the EVOH layer is E, and the adhesive resin layer is D. When the layer of the resin composition of the present invention is F, E / F / E, F / E / F,
F / F / F (F of the intermediate layer has a high EVOH content), F / F / F
/ D / E, F / D / E / D / F, P / E / P / F, P /
When a layer structure such as F / D / E / D / F / P and P / F / D / E / D / P is adopted, a beautiful molded product having good compatibility can be obtained. In such a multilayer molded product, a scrap of the multilayer molded product can be used as the resin composition.

As a multilayer molding method, generally, a number of extruders corresponding to the type of the resin layer are used, and the flow of the resin melted in the extruder is simultaneously extruded in a superposed layer form, that is, a so-called “multilayer extrusion method”. It is manufactured by co-extrusion. As another method, a method of molding by extrusion coating may be adopted. Thus, the molded product obtained from the resin composition of the present invention is excellent not only in that the resin composition layer is uniform and the appearance is beautiful, but also in compatibility, and in terms of strength, since it is uniform. Product, and its industrial significance is great.

[0027]

The present invention will be described more specifically with reference to the following examples.
Parts mean parts by weight.

Examples 1-3 Polypropylene resin (PP) Melt flow index (ASTM-D1238, 230 ° C) 0.5 g / 10
Min, containing Ti compound as catalyst residue (A), EVOH
｛Ethylene unit content 33 mol%, degree of saponification 99.9 mol%, melt index (190 ° C., 2160 g)
After dry blending 1.5 g / 10 min (B) and the hydrotalcite-based compound (C) at the ratios shown in Table 1, full flight having a diameter of 40 mm, L / D = 24, and a compression ratio of 3.8. Charge into an extruder having a mold screw, width 5
Melt film formation was performed using a 50 mm flat die. The film forming temperature is 190-230 ° C for the extruder and 2 for the die.
The temperature was set to 20 ° C., and a film having a thickness of 50 μm was wound by a take-up machine, and a continuous operation was performed for 6 hours. Table 1 also shows the evaluation of the film surface state and the hue of the obtained film.

Comparative Example 1 A film of a mixture of a polypropylene resin and EVOH was formed in the same manner as in Example 1 except that the hydrotalcite compound was not mixed. From around 30 minutes after the start of the operation, a large number of non-uniform phase-separated foreign substances not observed in Example 3 were observed, and the number increased with the passage of time, and the obtained film had poor color and extremely poor appearance. .

[0030]

[Table 1]

Note 1) The state of the film surface was evaluated according to the following criteria. Excellent: Uniform and good compatibility and no phase-separated foreign matter are observed, or uniform and good compatibility is exhibited, but small long-time phase-separated foreign matter is observed in long-time molding. Good: The compatibility is good, but some phase-separated foreign substances are slightly observed. Acceptable: The effect of improving the compatibility is seen, but the phase-separated foreign matter is slightly seen. Impossible: No effect of improving compatibility was observed, a large number of non-uniform phase-separated foreign substances were observed, the number of which increased with time, and the appearance of the obtained film was extremely poor.

Note 2) The evaluation of the hue of the film was determined according to the following criteria. A: No yellowing is observed. Good: Some yellowing is observed. Acceptable: slight yellowing is observed. Not possible: remarkable yellowing is observed.

Example 4 Isotactic polypropylene ｛density (ASTM-
D-1505) 0.906 g / cm ³ , melt index (ASTM-D-1238) 0.8 g / 10 min, Ti compound content which is a catalyst residue, and ethylene content 33
Mol%, saponification degree 99.9%, melt index 1.2
g / 10 minutes of EVOH [0.05% by weight of hydrotalcite {Ca ₆ Al ₂ (OH) ₁₆ CO ₃ .4H ₂ O}
EVOH melt-blended with OH and pelletized], and the same weight ratio of hydrotalcite as above is 98/2 /
0.1 mixture at room temperature with a Henschel mixer.
The mixture was prepared under the mixing conditions for minutes. The mixture obtained by such an operation was used to obtain a mixture having a diameter of 40 mm and an effective length of 800 m.
an extruder for an intermediate layer having a m.
An adapter having a built-in screw of 65 mm in diameter and 1430 mm in effective length for VOH (EVOH blended and pelletized with 0.05% by weight of hydrotalcite) and having a melt channel branched into two is provided. The inner and outer layer extruders perform melt coextrusion using a triple die for three layers at a temperature of 240 ° C., and the outer layer and the inner layer are the EVOH, and the intermediate layer is the symmetrical material of the blend by a known hollow molding method. A three-layered laminated circular bottle (bottle) was formed. As a result, even after 48 hours of continuous operation, uniform and good bottles were obtained, the state of the membrane surface of the blend layer was good, no phase-separated foreign matter due to poor compatibility was observed, and the blend layer was The hue of the film surface was good and no yellowing was observed. Each of the obtained bottles had an outer layer: intermediate layer: inner layer thickness ratio of 4.5: 1: 4.5,
The average thickness was about 600 μ, and the internal volume was about 280 cc.

Comparative Example 2 In the same manner as in Example 4 except that hydrotalcite was not used, a symmetrical three-layered laminated circular bottle was formed. As a result, from around 3 hours after the start of operation, a large number of non-uniform phase-separated foreign matters not found in Example 4 were generated, and the number increased over time, and the appearance of the obtained bottle was extremely poor.

[0035]

According to the present invention, polyolefin and EV
The compatibility of HO is remarkably improved, and the hue is also improved, whereby a molded article having a beautiful appearance and excellent physical properties is obtained, and also has excellent long-run properties.

Claims (4)

[Claims] 1. A method for compatibilizing a polyolefin (A) and a saponified ethylene-vinyl acetate copolymer (B), comprising using a hydrotalcite compound (C). 2. The method according to claim 1, wherein the polyolefin (A) is a polypropylene resin. 3. A saponified ethylene-vinyl acetate copolymer (B) having an ethylene unit content of 20 to 50 mol%,
The method according to claim 1 or 2, wherein the degree of saponification of the vinyl acetate unit is 96% or more. 4. The weight ratio of polyolefin (A): saponified ethylene-vinyl acetate copolymer (B) is 80: 20-9.
The compatibilizing method according to any one of claims 1 to 3, wherein the ratio is 9.9: 0.1.