JP3335201B2 - Polyvinyl alcohol resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyvinyl alcohol resin composition from which a molded article having excellent flexibility, particularly at low temperatures, can be obtained.

[0002]

2. Description of the Related Art Molded articles of polyvinyl alcohol resin,
For example, the film is excellent in properties such as fragrance retention, transparency, oil resistance, antistatic property, oxygen barrier property, heat retention property, and also has hydrophilicity, water solubility or water dispersibility, so that it is usually hydrophobic. It can also be used for applications that are not suitable for a film of a conductive polymer. In particular, a molded article made of an oxyalkylene group-containing polyvinyl alcohol has an excellent advantage that it is excellent in flexibility as compared with a molded article made of general polyvinyl alcohol and can be melt-molded without using a plasticizer, It is used for various purposes.

[0003] The following various domestic and foreign applications have been filed for oxyalkylene group-containing polyvinyl alcohol. For example, U.S. Pat.
844,570 and 2,990,398 disclose an polyvinyloxy alcohol group-containing polyvinyl alcohol obtained by adding ethylene oxide to polyvinyl alcohol. U.S. Pat. Nos. 3,033,841 and 4,369,281 disclose an oxyalkylene group-containing polyvinyl alcohol obtained by saponifying a polymer obtained by graft-polymerizing vinyl acetate in the presence of a polyalkylene glycol.
A call is shown. U.S. Pat. Nos. 4,618,648 and 4,675,360 show copolymers of vinyl alcohol and poly (alkyleneoxy) acrylates, which can be injection molded and extruded, It is also shown that the obtained molded product has water solubility and flexibility.

[0004] JP-A-59-1655408 discloses that
A modified polyvinyl alcohol obtained by saponifying a copolymer of an unsaturated monomer containing an oxyalkylene group and vinyl acetate is shown. In this publication, various kinds of uses are listed, and a molded article is also mentioned as an example of the use. Japanese Patent Application Laid-Open No. Hei 3-203932 filed by the present applicant discloses a method of melt-molding an oxyalkylene group-containing vinyl alcohol copolymer under substantially anhydrous conditions. This publication describes that molding is performed substantially without using a plasticizer, and that an extrusion molding method or an injection molding method can be employed as a molding method.

[0005]

The molded article comprising an oxyalkylene group-containing polyvinyl alcohol exhibits excellent flexibility as described above, but it is hard to say that it has sufficient flexibility at low temperatures. , Glycerin, polyethylene glycol, polypropylene glycol and the like have been added. However,
Such a plasticizer is desorbed over time, and it is difficult to maintain the initial flexibility for a long period of time. Therefore, there is a strong demand for a molded article having sufficient flexibility even at a low temperature and having no change over time for a long period of time.

[0006]

Means for Solving the Problems However, the present inventors have conducted intensive studies to solve such problems, and as a result, have found that polyvinyl alcohol (I) containing an oxyalkylene group, polyolefin resin (II), ethylene-vinyl acetate, It consists of saponified polymer (III), the compounding weight ratio of (I) / (II) is 99/1 to 50/50, and (III) is 0.5 to 20 with respect to (I) + (II). The present inventors have found that a polyvinyl alcohol-based resin composition in an amount of 1% by weight meets such an object, and have completed the present invention. In the present invention, the oxyalkylene group-containing polyvinyl alcohol, polyolefin-based resin and ethylene-vinyl acetate copolymer saponified product is only the effect of the present invention is melt blended in a specific blending ratio, it shows the effect of the present invention, In the composition of a saponified product of an alkylene group-containing polyvinyl alcohol and a polyolefin-based resin or an oxyalkylene group-containing polyvinyl alcohol and an ethylene-vinyl acetate copolymer, the flexibility at a low temperature of the molded product is improved, and the initial flexibility is extended for a long time. It is very difficult to hold.

Hereinafter, the present invention will be described in detail. The oxyalkylene group-containing polyvinyl alcohol (I) used in the present invention is typically vinyl acetate and polyoxyalkylene (meth) such as polyoxyethylene (meth) allyl ether and polyoxypropylene (meth) allyl ether. It is obtained by copolymerizing with allyl ether and then saponifying. In this case, the copolymerization ratio of the polyoxyalkylene (meth) allyl ether is 0.1 to 20.
Mol%, especially 0.1 to 5 mol%, the degree of condensation of polyoxyalkylene in polyoxyalkylene (meth) allyl ether is 1 to 300, especially 3 to 50, and the number of oxyalkylene units in the whole oxyalkylene group-containing polyvinyl alcohol is Preferably, the proportion is between 3 and 40% by weight. This indicates that there is an optimal range for the degree of localization-delocalization of the oxyalkylene unit and the length of the oxyalkylene unit in the copolymer.

The degree of saponification of vinyl acetate units in the oxyalkylene group-containing polyvinyl alcohol is 70 to 100.
Mol%, preferably 80 to 99 mol%, and the average degree of polymerization is 2
100 to 1000, preferably 300 to 700 is suitable. Components other than polyoxyalkylene (meth) allyl ether as copolymerization components, for example, α-olefins (ethylene, propylene, long-chain α-olefins, etc.), ethylenically unsaturated carboxylic acid monomers, (acrylate, methacrylate, acrylonitrile) , Methacrylonitrile, vinyl chloride, vinyl ether, etc.)
It may be contained if it is about the following. As a polymerization method for obtaining an oxyalkylene group-containing polyvinyl alcohol, a solution polymerization method is usually employed, and a suspension polymerization method, an emulsion polymerization method, or the like may be optionally employed.
As the saponification reaction, an alkali saponification method, an acid saponification method, or the like is employed.

In addition to the above, oxyalkylene group-containing polyvinyl alcohols include vinyl acetate, polyoxyethylene (meth) acrylate, polyoxypropylene (meth)
Acrylate, polyoxyethylene (meth) acrylamide, polyoxypropylene (meth) acrylamide,
Polyoxyethylene (1- (meth) acrylamide-
Polyoxyalkylene allylamines such as 1,1-dimethylpropyl) ester, polyoxyethylene vinyl ether, polyoxypropylene vinyl ether, polyoxyethylene allylamine, and polyoxypropylene allylamine, and polyoxyalkylene such as polyoxyethylene vinylamine and polyoxypropylene vinylamine It can also be obtained by copolymerizing an alkylene vinylamine or the like and then saponifying it. The oxyalkylene group-containing polyvinyl alcohol can also be obtained by a reaction of an alkylene oxide with polyvinyl alcohol, or a polymerization of vinyl acetate with polyoxyalkylene glycol followed by saponification.

In the present invention, the polyolefin resin (I)
I) refers to an olefin polymer having 2 to 6 carbon atoms,
In particular, it means a homopolymer or copolymer of ethylene, propylene or butene. They are, for example, ultra low density polyethylene, low density polyethylene, medium density polyethylene,
High-density polyethylene, polypropylene homopolymer and ethylene propylene copolymer, polyethylene, ethylene, butene, copolymerized with vinyl acetate, vinyl acrylate, butene, hexane or 4-methyl-1 pentene, etc.
Polypropylene copolymerized with hexene or 4-methyl-1-pentene, modified polypropylene blended with a rubber-based polymer, poly-1-butene, polyhexene, poly-4-methyl-1-pentene, ionomer resin, or the above-mentioned polyolefin And modified polyolefin and oxidized polyolefin obtained by reacting maleic anhydride.

The polyolefin resin has a compounding weight ratio (I) / (II) of 99/1 to 50/50, preferably 95/5 to 60/40. If the ratio exceeds the specified range, the inherent properties of the polyvinyl alcohol-based resin (fragrance retention, transparency, oil resistance, oxygen barrier properties, etc.) will be reduced. The saponified ethylene-vinyl acetate copolymer (III) in the present invention has an ethylene content of 5 to 95 mol%, preferably 10 to 80 mol%, and a saponification degree of the vinyl acetate portion of 5%.
It is 0 to 100 mol%, preferably 70 to 100 mol%. The saponified ethylene-vinyl acetate copolymer is obtained by saponification of an ethylene-vinyl acetate copolymer, and the ethylene-vinyl acetate copolymer is produced by any known polymerization method, usually a solution polymerization method. .

The saponification of the ethylene-vinyl acetate copolymer can be carried out by a known method. For example, in a homogeneous system in an alcoholic solvent such as methanol, or a heterogeneous system in a mixed solvent obtained by adding alcohols such as methanol and ethanol and water as needed, hydroxides of sodium and potassium, alkoxides and the like. A method of saponifying an alkali metal compound or an acid catalyst such as hydrochloric acid, sulfuric acid, acetic acid or the like as a saponification catalyst may be used. The amount of the saponified ethylene-vinyl acetate copolymer is (I) + (II)
0.5 to 20% by weight, preferably 1 to 10% by weight. When the amount is less than 0.5% by weight, sufficient flexibility cannot be imparted. When the amount exceeds 20% by weight, the inherent properties of the polyvinyl alcohol-based resin (fragrance retention, transparency, oil resistance, oxygen barrier properties) Etc.).

The method of blending the oxyalkylene group-containing polyvinyl alcohol (I), the polyolefin-based resin (II) and the saponified ethylene-vinyl acetate copolymer (III) to obtain the resin composition of the present invention is usually good. The mixture is melt-kneaded and mixed by a known method, that is, an extruder, a roll kneader or a Banbury mixer. There is no particular restriction on the blending order either, and a method of blending three kinds of resins simultaneously or a method of blending two kinds of resins and then blending the remaining resin may be used. Furthermore, the molding method of the resin molded product is to perform melt molding using the blend obtained by the above method, but each component is not melt-blended in advance, but is charged separately to a molding machine and directly in the molding machine. A method of melting or injection molding immediately after melt blending is also possible.

The polyvinyl alcohol resin composition thus obtained is melt-molded. In melt molding,
Various additives such as a plasticizer, a filler, a colorant, and a stabilizer can be blended. Further, other polymers can be blended within a range that does not impair the gist of the present invention, or conversely, the above-mentioned polyvinyl alcohol-based resin composition can be blended with another polymer. Examples of the melt molding method include an injection molding method, an extrusion molding method, and a transfer molding method. Note that the extrusion molding includes blow molding, inflation molding, coextrusion molding, extrusion coating, and the like. As the injection conditions, for example,
Cylinder temperature around 150-250 ° C, mold temperature 10-
About 100 ° C, injection pressure 500-2000Kg / cm ²
A degree condition is employed. The extrusion molding conditions are preferably set, for example, by setting the die temperature to about 150 to 250 ° C. and setting the screw compression section temperature to 5 to 30 ° C. higher than the discharge section temperature.

The form of the molded product is not particularly limited, and examples thereof include bottles, films, sheets, hoses, tubes, containers, bags, fibers, foams, and various members obtained by injection molding. The polyvinyl alcohol-based resin composition of the present invention is a hot melt adhesive in addition to a molded product,
It can be used for various purposes such as paper processing agents, packaging materials, stationery, office supplies, sanitary supplies, medical supplies, agricultural and horticultural supplies, and machine parts.

[0016]

The molded article made of the polyvinyl alcohol-based resin composition of the present invention has excellent flexibility, and particularly has improved flexibility at low temperatures, and is extremely industrially advantageous.

[0017]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples. << Production of Molded Article >> Example 1 Oxyalkylene Group-Containing Polyvinyl Alcohol Average Degree of Polymerization: 360 Copolymerization Ratio of Polyoxyethylene Monoallyl Ether (oxyethylene Condensation Degree is 30) Units: 1.5 mol% of the Total Polymer Ratio of oxyalkylene units: 3
0% by weight Saponification degree of vinyl acetate component: 95 mol% MFR value: 23 g / 10 min Low density polyethylene MFR value: 22 g / 10 min

[0018]Saponified ethylene-vinyl acetate copolymer  Ethylene content: 50 mol% Degree of saponification of vinyl acetate component: 99 mol% MFR value: 25 g / 10 min A round die is provided with the above resin at a blending ratio shown in Table 1.
And extrude at a temperature of 210 ° C.
As a result, a pellet-shaped resin composition was obtained. Obtained resin set
Physical properties of the product were measured by the following methods. The result is
The results are shown in Table 1. The MFR value is the value of the melt indexer.
(Toyo Seiki Co., Ltd.), 210 ° C., load 216
It was measured at 0 g. (Hereinafter the same)

Example 2 An experiment was conducted in the same manner as in Example 1 except that the following resins were blended at the blend ratios shown in Table 1. The results are summarized in Table 1. Oxyalkylene group-containing polyvinyl alcohol Average polymerization degree: 500 Copolymerization ratio of polyoxyethylene monoallyl ether (oxyethylene condensation degree: 10) units: 2.0 mol% Ratio of oxyalkylene units in the whole polymer: 1
5.4% by weight Saponification degree of vinyl acetate component: 90 mol% MFR value: 7 g / 10 min Low-density polyethylene MFR value: 12 g / 10 min Saponified ethylene- vinyl acetate copolymer Ethylene content: 70 mol% Vinyl acetate component Degree of saponification: 99 mol% MFR value: 8 g / 10 min

Example 3 An experiment was conducted in the same manner as in Example 1 except that the following resins were blended at the blend ratios shown in Table 1. The results are summarized in Table 1. Oxyalkylene group-containing polyvinyl alcohol average polymerization degree: 750 Copolymerization ratio of polyoxyethylene monoallyl ether (oxyethylene condensation degree is 5) units: 2.0 mol% Ratio of oxyalkylene units to the whole polymer:
8.9% by weight Saponification degree of vinyl acetate component: 98 mol% MFR value: 0.3 g / 10 min Low density polyethylene MFR value: 20 g / 10 min Saponified ethylene- vinyl acetate copolymer Ethylene content: 30 mol% acetic acid Degree of saponification of vinyl component: 90 mol% MFR value: 12 g / 10 min

Example 4 An experiment was conducted in the same manner as in Example 1 except that the following resins were blended at the blend ratios shown in Table 1. The results are summarized in Table 1. Oxyalkylene group-containing polyvinyl alcohol average polymerization degree: 900 Copolymerization ratio of polyoxyethylene monoallyl ether (oxyethylene condensation degree is 15) units: 2.5 mol% Ratio of oxyalkylene units in the whole polymer: 2
6.2% by weight Saponification degree of vinyl acetate component: 91 mol% MFR value: 0.1 g / 10 min Low density polyethylene MFR value: 20 g / 10 min Saponified ethylene- vinyl acetate copolymer Ethylene content: 85 mol% acetic acid Degree of saponification of vinyl component: 80 mol% MFR value: 7 g / 10 min

Example 5 An experiment was conducted in the same manner as in Example 1 except that the following resins were blended at the blend ratios shown in Table 1. The results are summarized in Table 1. Oxyalkylene group-containing polyvinyl alcohol average polymerization degree: 560 Copolymerization ratio of polyoxyethylene monoallyl ether (oxyethylene condensation degree is 5) units: 4.0 mol% Ratio of oxyalkylene units in the whole polymer: 1
5.8% by weight Saponification degree of vinyl acetate component: 94 mol% MFR value: 2 g / 10 min Medium density polyethylene MFR value: 4 g / 10 min Ethylene-vinyl acetate copolymer saponified ethylene content: 40 mol% Vinyl acetate component Degree of saponification: 90 mol% MFR value: 2 g / 10 min

Example 6 An experiment was conducted in the same manner as in Example 1 except that the following resins were blended at the blend ratios shown in Table 1. The results are summarized in Table 1. Oxyalkylene group-containing polyvinyl alcohol average polymerization degree: 560 Copolymerization ratio of polyoxyethylene acrylamide (oxyethylene condensation degree is 30) units: 1 mol% Ratio of oxyalkylene units in the whole polymer: 2
2.5% by weight Saponification degree of vinyl acetate component: 97 mol% MFR value: 2 g / 10 min Medium density polyethylene MFR value: 4 g / 10 min Saponified ethylene- vinyl acetate copolymer Ethylene content: 65 mol% Vinyl acetate component Degree of saponification: 99 mol% MFR value: 2 g / 10 min

Example 7 An experiment was conducted in the same manner as in Example 1 except that the following resins were blended at the blend ratios shown in Table 1. The results are summarized in Table 1. Oxyalkylene group-containing polyvinyl alcohol average polymerization degree: 450 Copolymerization ratio of polyoxyethylene vinyl ether (condensation degree of oxyethylene is 40) units: 1.0 mol% Ratio of oxyalkylene units in the whole polymer: 2
7.8% by weight Saponification degree of vinyl acetate component: 96 mol% MFR value: 8 g / 10 min Polypropylene MFR value: 6.5 g / 10 min Saponified ethylene- vinyl acetate copolymer Ethylene content: 75 mol% Vinyl acetate component Degree of saponification: 95 mol% MFR value: 6 g / 10 min

Example 8 The following resins were blended at the blend ratios shown in Table 1.
Except for the above, the experiment was performed according to Example 1. The results are summarized
It is shown in Table 1.Oxyalkylene group-containing polyvinyl alcohol  Average degree of polymerization: 400 polyoxypropylene vinyl ether (oxyethylene
Is a degree of condensation of 8) the copolymerization ratio of units: 3.0 mol% The ratio of oxyalkylene units to the whole polymer: 2
3.5% by weight Saponification degree of vinyl acetate component: 97 mol% MFR value: 20 g / 10 minpolypropylene MFR value: 20 g / 10 minSaponified ethylene-vinyl acetate copolymer Ethylene content: 85 mol% Degree of saponification of vinyl acetate component: 99 mol% MFR value: 22 g / 10 min

Comparative Example 1 An experiment was conducted in the same manner as in Example 1 except that low-density polyethylene was not blended. The results are summarized in Table 1. Comparative Example 2 An experiment was performed in the same manner as in Example 1 except that the saponified ethylene-vinyl acetate copolymer was not blended. The results are summarized in Table 1. Comparative Example 3 An experiment was performed according to Example 1, except that glycerin was used instead of low-density polyethylene. Table 1 summarizes the results
Shown in Comparative Example 4 An experiment was performed according to Example 1, except that polyethylene glycol was used instead of low-density polyethylene. Table 1 shows the results. Comparative Example 5 An experiment was performed in the same manner as in Example 1 except that the mixing ratio of the oxyalkylene group-containing polyvinyl alcohol and the low-density polyethylene was out of the specified range as shown in Table 1. The results are summarized in Table 1. Comparative Examples 6 and 7 Table 1 shows the amount of saponified ethylene-vinyl acetate copolymer.
The experiment was performed according to Example 1 except that the value was outside the specified range as described above. The results are summarized in Table 1. 《Test method and evaluation result》

Flexibility Using the pellets obtained above, width 3 cm × length 15 c
A test piece having a size of mx 2.5 mm in thickness is molded by injection molding, and is subjected to 3 days at 20 ° C and 65% RH (leaved in an environmental test chamber) and 3 days or -30 ° C (leaved in a freezer). Left for days. One of these test pieces was fixed with a vice (sandwiched to 2 cm from the end), and the other was bent downward to evaluate flexibility. The criteria are as follows. ◎: No change even after holding at θ = 45 ° C. for 10 minutes ○: No break until θ = 45 ° C., but cracks after holding for 10 minutes △: Fold at 30 ° C. <θ <45 ° C. ×: θ ≦ Fold at 30 ° C (θ indicates the angle of bending of the test piece downward from the horizontal state)

[0028]

[Table 1] (Note) EO-PVA: oxyalkylene group-containing polyvinyl chloride
Alcohol PO: polyolefin-based resin EVOH: saponified ethylene-vinyl acetate copolymer The amount of EVOH added is a weight relative to (EO-PVA + PO).
Indicate in%

[0029]

Industrial Applicability The present invention relates to an oxyalkylene group-containing polyvinyl alcohol, a polyolefin resin, an ethylene-
By mixing the saponified vinyl acetate copolymer at a specific compounding ratio, the flexibility of a molded article made of such a resin composition was improved, particularly at low temperatures.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C08L 29/04 CA (STN) REGISTRY (STN)

Claims (3)

(57) [Claims] 1. An oxyalkylene group-containing polyvinyl alcohol (I), a polyolefin resin (II), a saponified ethylene-vinyl acetate copolymer (III), and (I)
/ (II) is 99/1 to 50/50 and (II)
Polyvinyl alcohol resin composition wherein I) is 0.5 to 20% by weight based on (I) + (II) 2. An oxyalkylene group-containing polyvinyl alcohol having a saponification degree of 70 to 100 mol% and an average polymerization degree of 20.
The polyvinyl alcohol-based resin composition according to claim 1, which is 0 to 1,000. 3. The polyvinyl alcohol according to claim 1, wherein 50 to 100 mol% of the vinyl acetate portion of the saponified ethylene-vinyl acetate copolymer is saponified, and the ethylene content is 5 to 95 mol%. Resin composition