JPH09136924A - Composite polymer having both hydrophobicity and hydrophilicity and its preparation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composite polymer, possessing both hydrophobicity and hydrophilicity and having a basic structure comprising a polyolefin as a hydrophobia polymer and polyvinyl alcohol as a hydrophilic polymer, which has improved homogeneous and fine dispersibility of both the polymers and good balance between the hydrophobicity and the hydrophilicity and to provide a process for preparing the same. SOLUTION: This composite polymer having both hydrophobicity and hydrophilicity comprises a polymer reaction product comprising a polyolefin (A), a polyvinyl alcohol (B) having a mercapto group in its terminal, and a monomer (C) which can be grafted onto the polyolefin and the mercapto group. It is prepd. by reacting the mercapto group of polyvinyl alcohol (B) with a product of a graft reaction between the polyolefin (A) and the monomer (C). This composite polymer is chemically bonded and has an homogeneously and finely dispersed internal structure, a good balance between the hydrophilicity and the hydrophobicity and stable properties.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a composite polymer having both hydrophobicity and hydrophilicity, which contains polyolefin as a hydrophobic polymer and polyvinyl alcohol as a hydrophilic polymer as a basic structure, and a method for producing the same.
The present invention relates to a thermoplastic composite polymer and a polymer composition that can be used as a sheet or a film by extrusion molding or the like.

[0002]

2. Description of the Related Art Polyolefin, which is a hydrophobic polymer, is used in various applications because it has excellent properties such as moldability and mechanical strength. For example, when it is used as a transparent film, static electricity is generated. There are also reports of cases in which dust and dirt adhere to the surface to reduce transparency, and when used as an agricultural film, water droplets on the surface act like lenses to damage crops. Has been done. On the other hand, polyvinyl alcohol is a hydrophilic polymer and is used in surface coating agents and adhesives for paperboard, sizing agents for textiles and paper, book binders, etc., and its film is difficult to be charged and has excellent transparency and gloss. However, it is well known that the water resistance is poor. For this reason, it is considered that the combination of both polymers will complement the drawbacks, and various techniques have been developed in the past. As a method of imparting hydrophilicity to polyethylene or imparting hydrophobicity to polyvinyl alcohol, the most common method is to use a polymer blend of both, but when polyethylene and polyvinyl alcohol which are incompatible systems are simply melt-kneaded, Coarse domains are formed and the resulting polymer composition is inhomogeneous. As a result, stable physical properties cannot be obtained, and on the contrary, it becomes a material in which the defects of both polymers are conspicuous.

As an improvement, for example, Japanese Patent Laid-Open No. 4-2873
No. 3 is a modified polyolefin containing a polyolefin-based resin and a polyvinyl alcohol-based resin and one or more functional groups selected from a carboxyl group, a non-hydroxyl group, a silanol group, an epoxy group, an amino group and a quaternary ammonium salt. A system resin is blended and melt-kneaded. Further, in Japanese Unexamined Patent Publication No. 6-192511, reactive extrusion is performed in which unsaturated carboxylic acid or anhydride is added during grafting of a polyolefin for grafting, and polyvinyl alcohol is melt-blended. Further, in JP-A-6-145267, in order to improve the compatibility of the polyolefin and the second polymer which is incompatible with the polyolefin, a reactive low-molecular compound (carboxylic acid, anhydride, etc.) capable of reacting with both at the time of kneading is used. A mixture of initiators). There is also an attempt to react polyethylene having a maleic acid group with polyvinyl alcohol itself to obtain a uniform mixture (No.
rman G. Gaylord et al., Soc.Plast.Eng.Annu.Tech.Conf., 5
Volume 2, Issue 2, pp. 1646-1648, 1994).

However, since these are aimed at the reaction between the introduced functional group or reactive low molecular weight compound and the like and the hydroxyl group contained in the structural unit of polyvinyl alcohol, it is difficult to control the reaction, and in practice If the degree of reaction is low, a uniform fine dispersion cannot be obtained, and if the reaction proceeds excessively, the dispersion will be uniform, but the system will gel and will not be a practical molding material. Therefore, there is an industrial demand for a technique for homogenizing or finely dispersing these polymers.

[0005]

DISCLOSURE OF THE INVENTION The present invention is a polymer having both hydrophobicity and hydrophilicity, which comprises polyolefin as a hydrophobic polymer and polynyl alcohol as a hydrophilic polymer as a basic structure. Further, the present invention aims to provide a composite polymer having a well-balanced hydrophobicity and hydrophilicity with improved fine dispersibility, and a method for producing the same.

[0006]

Means for Solving the Problems The present inventors have conducted extensive studies to solve the problems of the prior art, and as a result, use a polyolefin and polyvinyl alcohol having a mercapto group at the end as a polymer raw material, A polymer reaction product is obtained by chemically reacting a polymer raw material with a monomer that can be graft-reacted with polyolefin and that can react with a mercapto group. The internal structure of this polymer reaction product is uniformly finely dispersed. A compatibilizing agent that exhibits stable physical properties in which hydrophilicity and hydrophobicity are well-balanced and that the polymer reaction product is melt-kneaded with a mixture of polyolefin and polyvinyl alcohol that are incompatible as described above. Plays an important role and evenly disperses the domain, and improves the adhesiveness of the interface without deteriorating the physical properties. It found that it is possible to aqueous or hydrophobic imparting, in which the present invention has been completed.

That is, the present invention includes the following aspects. A first invention is a polymer reaction product comprising (A) a polyolefin, (B) a polyvinyl alcohol having a mercapto group at the terminal, and (C) a monomer which can be graft-reacted with a polyolefin and which can react with a mercapto group. ,
(A) A composite polymer having both hydrophobicity and hydrophilicity, which is obtained by reacting a graft reaction product of a polyolefin and the (C) monomer with a mercapto group of the (B) polyvinyl alcohol. The second invention is (C) a monomer capable of graft-reacting a mixture of (A) a polyolefin and (B) a polyvinyl alcohol having a mercapto group at its end with a monomer capable of reacting with a mercapto group, and (D). By melting and kneading with an organic peroxide, the graft reaction of the (A) polyolefin and the (C) monomer, and the mercapto group of the (B) polyvinyl alcohol and the (C) monomer are reacted. And a method for producing a composite polymer having both hydrophobicity and hydrophilicity. A third invention is a polyolefin graft reaction product obtained by melt-kneading (A) a polyolefin with (C) a polyolefin capable of undergoing a graft reaction and a monomer capable of reacting with a mercapto group and (D) an organic peroxide. And (B) a method for producing a composite polymer having both hydrophobicity and hydrophilicity, which comprises melt-kneading polyvinyl alcohol having a mercapto group at the terminal to react the mercapto group. A fourth invention relates to a thermoplastic polymer composition obtained by melt-kneading a mixture of polyolefin and polyvinyl alcohol with the composite polymer having both hydrophobicity and hydrophilicity described in the first invention.

The (A) polyolefin used in the present invention is generally polyethylene (low density polyethylene, medium density polyethylene, high density polyethylene, linear low density polyethylene, etc.), polypropylene, ethylene-propylene copolymer, etc. Various polyolefins used for extrusion molding are used, and the melt index at 190 ° C. is 0.01 to 100 / g10 minutes, preferably 0.05.
The one used is about 50 g / 10 minutes. The polyvinyl alcohol having a mercapto group at the terminal (B) used in the present invention has a saponification degree of 60 to 90, preferably 80.
-90, degree of polymerization 50-2000, preferably 100-10
It is polyvinyl alcohol of No. 00, and can be obtained by introducing a mercapto group into one end of the main chain by coexisting a thiol compound at the time of polymerization of vinyl acetate and then saponifying (Kazutoshi Terada, et al. , Volume 49, 1
No. 1, pp. 885-891, 1992). To the polyvinyl alcohol having a mercapto group at its terminal, a plasticizer such as glycerin or low molecular weight polyethylene glycol may be added as long as the reactivity of the mercapto group is not impaired.

Examples of the monomer (C) that can be graft-reacted with the polyolefin and can react with the mercapto group used in the present invention include glycidyl methacrylate, glycidyl acrylate, allyl glycidyl ether, glycidyl monomaleate, Epoxy group-containing vinyl monomers such as glycidyl dimaleate, divinylbenzene, ethylene glycol di (meth) acrylate having 1 to 6 ethylene glycol units, propylene glycol di (meth) having 1 to 6 propylene glycol units Examples thereof include monomers having two vinyl groups in one molecule such as acrylate.

Further, the organic peroxide (D) used in the present invention includes ketone peroxide, ketal peroxide, hydroperoxide, dialkyl peroxide, diacyl peroxide, dicarbonate peroxide, and peroxide ester. In the molecule such as
Any organic peroxide having a bond such as methyl ethyl ketone peroxide, cyclohexanone peroxide, 3,3,5-trimethylcyclohexanone peroxide, methyl cyclohexanone peroxide, methyl acetoacetate peroxide, and acetylacetone peroxide can be used. Ketone, 1,1-bis (t-butylperoxy) cyclohexane, 2,2-
Peroxide ketals such as bis (t-butylperoxy) octane and 2,2-bis (t-butylperoxy) butane,
t-butyl hydroperoxide, 2,5-dimethylhexane 2,5-dihydroperoxide, 1,1,
Hydroperoxides such as 3,3-tetramethylbutyl hydroperoxide, di-t-butyl peroxide,
t-Butylcumyl peroxide, di-cumyl peroxide, dialkyl peroxide such as 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, acetyl peroxide, isobutyl peroxide, octanoyl peroxide , Decanoyl peroxide, 3,
Diacyl peroxide such as 5,5-trimethylhexanoyl peroxide and benzoyl peroxide, di-isopropyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, di-n-propyl peroxydicarbonate, di-2 -Peroxydicarbonate such as ethoxyethylperoxydicarbonate, di-methoxyisopropylperoxydicarbonate, di-allylperoxydicarbonate, t-butylperoxyisobutyrate, t-butylperoxyisopropylcarbonate, etc. Examples thereof include peroxide ester.

The above mentioned constituents of the composite polymer of the present invention
The blending ratio of (A) polyolefin and (B) terminal polyvinyl alcohol having a mercapto group is 98: 2 to 2: 9.
It can be used in an amount of 8 parts by weight, preferably 95: 5 to 5:98 parts by weight. When the blending ratio of the polyolefin is 2 parts by weight or less, the hydrophobicity is not sufficiently imparted to the polyvinyl alcohol, and when the blending ratio of the polyvinyl alcohol is 2 parts by weight or less, the hydrophilicity is not imparted to the polyolefin. Will be enough. In addition, the compounding ratio of the monomer (D) that can be graft-reacted to the polyolefin (C) and that can react with the mercapto group and the organic peroxide (D) is (C) unit polyolefin based on 100 parts by weight. 1 to 50 parts by weight of the monomer, preferably 5 to 30 parts by weight, and (D) 0.01 to 10 parts by weight, preferably 0.05 to 6 parts by weight of the organic peroxide, and (C) the monomer ( D) The ratio of organic peroxide is 1: 0.0
It is preferable to blend in the range of 1 to 0.20. If the amount of the (C) monomer exceeds 50 parts by weight, the (C) monomer may be homopolymerized during the melt-kneading, which will be described later. If the amount of the (C) monomer is less than 1 part by weight, the amount of graft reaction to the polyolefin is insufficient. Will be enough.
When the ratio of the (D) organic peroxide to the (C) monomer is less than 0.01, homopolymerization of the (C) monomer proceeds,
If it exceeds 0.20, the (A) polyolefin may gel.

In producing the composite polymer having both hydrophobicity and hydrophilicity of the present invention, (A) polyolefin and (B)
Melting a mixture consisting of polyvinyl alcohol having a mercapto group at the end together with (C) a monomer that can be graft-reacted with polyolefin and a monomer that can react with a mercapto group and (D) an organic peroxide at a kneading temperature of 180 to 230 ° C. By kneading, it can be produced by grafting the (A) polyolefin with the (C) monomer and by reacting the (B) mercapto group of the polyvinyl alcohol with the (C) monomer. Similarly, by melt-kneading (A) polyolefin with (C) a monomer capable of grafting reaction with polyolefin and (D) an organic peroxide capable of reacting with a mercapto group at a kneading temperature of 180 to 230 ° C. The resulting polyolefin graft reaction product, (B)
It can also be produced by melt-kneading polyvinyl alcohol having a mercapto group at the terminal and reacting it with the mercapto group. As the kneading device used for the above melt kneading, a twin-screw extruder, a single-screw extruder, a roll kneader,
Various kneading machines such as a Banbury mixer, a Henschel mixer, and a Brabender are used, but in carrying out the present invention, it is preferable to adjust the kneading temperature to 180 to 230 ° C. and perform melt kneading. When the kneading temperature is lower than 180 ° C., the melting is insufficient and fine dispersion is difficult, and when the kneading temperature is higher than 230 ° C., polyvinyl alcohol may generate gas and thermally decompose.

In the above melt-kneading operation, if necessary, additives such as pigments, dyes, stabilizers, plasticizers, ultraviolet absorbers, antioxidants, lubricants and fillers are added to the extent that the basic properties are not impaired. Also, an elastomer or the like that imparts flexibility can be added. According to the method of the present invention, an increase in melt viscosity is observed during melt kneading, and (B) a polyvinyl alcohol having a mercapto group at the end is (C).
Since the extraction ratio of polyvinyl alcohol in water by reacting with the monomer is very small, it is presumed that the desired composite polymer having both hydrophobicity and hydrophilicity is formed.

This composite polymer has the properties of ordinary thermoplastic resins, and can be processed into a film or sheet having both hydrophobicity and hydrophilicity by, for example, an extrusion molding method. Further, this composite polymer can function as a compatibilizer by melt-kneading with a mixture of ordinary polyolefin and polyvinyl alcohol, and the blending ratio of polyolefin and polyvinyl alcohol is 2: 9.
It can be applied to a mixture of 8 to 98: 2 parts by weight, preferably 5:98 to 98: 5 parts by weight.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Next, Examples and Comparative Examples of the present invention will be specifically described, but the present invention is not intended to be limited to these descriptions. In addition, each physical property is measured by the following method. [Average domain size] The obtained composite polymer was freeze-fractured and observed with a scanning electron microscope. [Extraction rate] The obtained composite polymer was formed into a film by press molding, the dry weight thereof was measured, and the mixture was allowed to stand in water at 60 ° C for 24 hours to elute the polyvinyl alcohol (PVA) component, and further dried for 24 hours to obtain the weight. The extraction rate A was calculated from the difference. Moreover, the extraction ratio B was calculated with respect to the total amount of PVA components in the composite polymer. * Extraction rate A = (W1-W0) ÷ W0 × 100 * Extraction rate B = (extraction rate A) ÷ Φ for the total amount of PVA components
(PVA) (W0: initial dry weight, W1: dry weight after extraction test, Φ (PVA): volume fraction of PVA.) [Contact angle] The obtained composite polymer is formed into a film by press molding, The contact angle of water with respect to the samples before and after the extraction test was measured at room temperature by the droplet method, and shown as a value of θ / 2. [Izod impact test] The obtained composite polymer was injection-molded and measured by ASTM-D256.

Example 1 The following operations were carried out at the compounding ratios shown in Test Nos. 1, 3, 5, 7 and 9 of Table 1 (numerical values in Table 1 indicate parts by weight).
About 1 polyethylene (MIRASON F312 manufactured by Mitsui Petrochemical Co., Ltd.)
In the process of melt-kneading with a twin-screw extruder at 90 ° C., benzoyl peroxide or 2,2 as an organic peroxide is used.
A mixture of 5-dimethyl-2,5-di (t-butylperoxy) hexane and an organic peroxide composed of glycidyl methacrylate or divinylbenzene as a monomer and a monomer is dropped from an air vent of a twin-screw extruder. By doing so, the polyethylene and the monomer were graft-reacted to obtain a polyethylene graft reaction product. To this polyethylene graft reaction product, polyvinyl alcohol having a mercapto group at one end (M polymer M-205 manufactured by Kuraray Co., Ltd.,
A polymer having a degree of polymerization of 500 and a degree of saponification of 87 to 89) was dry-blended, then melt-kneaded at about 225 ° C. in a twin-screw extruder and extruded to obtain a composite polymer. Table 3 shows the results of tests of various characteristics using this composite polymer.

Example 2 The following operations were carried out at the compounding ratios shown in test numbers 2, 4, 6, 8 and 10 in Table 1. Polyethylene (Mitsui Petrochemical Co., Ltd.
MIRASON F312) and polyvinyl alcohol having a mercapto group at one end (M polymer M-205 manufactured by Kuraray Co., polymerization degree 500, saponification degree 87 to 89) are dry blended,
In the process of melt-kneading with a twin-screw extruder at about 225 ° C., benzoyl peroxide or 2,5-dimethyl-2,5-di (t-butylperoxy) hexane as an organic peroxide, and a monomer as a monomer By adding a mixed solution of an organic peroxide consisting of glycidyl methacrylate or divinylbenzene and a monomer from an air vent of a twin-screw extruder, a graft reaction between polyethylene and a monomer and a mercapto group and a monomer of polyvinyl alcohol Was reacted and melt-extruded to obtain a composite polymer. Table 3 shows the results of tests of various characteristics using this composite polymer.

Example 3 Test Nos. 11 and 12 were carried out by the following procedure. Polyethylene (MIRASON F312 manufactured by Mitsui Petrochemical Co., Ltd.) 70 parts by weight and polyvinyl alcohol (Poval-405 manufactured by Kuraray Co., Ltd.) 30
5 parts by weight of the composite polymer obtained in Test No. 3 in Table 1 was blended into a mixture consisting of parts by weight (Test No. 11), and the same mixture was mixed with Composite Polymer 20 obtained in Test No. 4 in Table 1.
Each polymer composition obtained by melt-kneading and extruding each compounding compounding part by weight (test number 12) at about 225 ° C. in a twin-screw extruder was subjected to an Izod impact test.

Comparative Example 1 The following operations were carried out with the compounding ratios shown in test numbers 13 to 17 in Table 2 (numerical values in Table 2 indicate parts by weight). A mixture of polyethylene (MIRASON F312 manufactured by Mitsui Petrochemical Co., Ltd.) and polyvinyl alcohol (Poval-405 manufactured by Kuraray Co., Ltd.) was dry-blended, and then melt-extruded at about 225 ° C. by a twin-screw extruder. Table 3 shows the results of tests of various characteristics using this resin composition.

Comparative Example 2 The following operations were carried out with the compounding ratios shown in test numbers 18 to 20 in Table 2. Carboxyl groups 4, 9, and 12 in the molecular chain
Three kinds of ethylene-methacrylic acid copolymers containing mol% (Nucrel N4214C manufactured by Mitsui DuPont Polychemical Co., Ltd.,
A mixture of N0908C, N1207C) and polyvinyl alcohol (Poval-405 manufactured by Kuraray Co., Ltd.) was dry-blended and then melt-extruded by a twin-screw extruder at about 225 ° C. Table 3 shows the results of tests of various properties using this resin composition.
It was shown to.

Comparative Example 3 The following operation was carried out with the compounding ratio shown in test No. 21 in Table 2. A mixture of maleic acid-modified polyethylene (Admer LF300 manufactured by Mitsui Petrochemical Co., Ltd.) and polyvinyl alcohol (Poval-405 manufactured by Kuraray Co., Ltd.) was dry-blended and then melt-extruded at about 225 ° C. by a twin-screw extruder. Table 3 shows the results of tests of various characteristics using this resin composition.

[0022]

[Table 1]

[0023]

[Table 2]

[0024]

[Table 3]

As can be seen from the test results in Table 3, the composite polymers (Test Nos. 1 to 10) obtained by the method of the present invention in Examples 1 and 2 were the mere melting of polyethylene and polyvinyl alcohol in Comparative Example 1. The domain size is greatly reduced and the extraction rate is also extremely low, as compared with the extrusion compositions (test numbers 13 to 17) having the same PE: PVA (weight ratio) ratio. It is presumed that this is because the composite polymer of the present invention achieved the miniaturization of domains and the immobilization of both polymers by the grafting reaction and the chemical reaction of the mercapto group. Further, the composite polymer of the present invention, by retaining the hydrophilic component in the polymer, it is possible to maintain its shape even after contact with water, there is little difference in contact angle before and after the extraction test, hydrophilic to the hydrophobic resin. It is considered that the impartation of properties or the impartation of hydrophobicity to the hydrophilic resin has been achieved.

In Comparative Example 2 (Test Nos. 18 to 20), the domain size was reduced by using an ethylene-methacrylic acid copolymer having a carboxyl group instead of polyethylene, but polyvinyl alcohol was simply hydrogen. Most of the domains are extracted, only lowering the surface tension by binding. Therefore, the contact angle after the extraction test decreases, and when the amount of polyvinyl alcohol is large, the initial shape cannot be maintained, and the impartation of hydrophilicity or the impartation of hydrophobicity is insufficient.

In Comparative Example 3 (Test No. 21), by using maleic acid-modified polyethylene in place of polyethylene, effects such as miniaturization of domain size and reduction of extraction rate are observed as in the case of graft formation. However, a side reaction occurred and the state was close to that of gel, and there was a problem in moldability such that it was difficult to prepare a molded product sample used for evaluation. Regarding the test number 3 of Example 1, the test number 4 of Example 2, the test numbers 11 to 12 of Example 3, and the test number 14 of Comparative Example 1 in which PE: PVA (weight ratio) is 70:30. As a result of the Izod impact test, Fig. 1
As shown in FIG. 6, in each of the examples, a value higher than that of the comparative example 1 was obtained.

[0028]

INDUSTRIAL APPLICABILITY The composite polymer of the present invention uses polyolefin and polyvinyl alcohol having a mercapto group at the end as a polymer raw material, and a monomer which can be graft-reacted with a polyolefin and which can react with a mercapto group is chemically used as a polymer raw material. A polymer reaction product obtained by reacting it reactively, and the polymer reaction product is chemically reactively bonded, and its internal structure is uniformly finely dispersed to achieve a stable balance between hydrophilicity and hydrophobicity. Shows the physical properties of Further, according to the method of the present invention, it is possible to effectively produce a composite polymer having both a hydrophilic property and a hydrophobic property, which has a fine average domain size and a small extraction ratio of a polyvinyl alcohol component into water. Furthermore, by melting and kneading this composite polymer with a mixture of incompatible polyolefin and polyvinyl alcohol, it plays the role of a compatibilizer and evenly disperses the domains, and also improves the adhesiveness of the interface, thus lowering the physical properties. It is possible to impart hydrophilicity or hydrophobicity without the need.

[Brief description of the drawings]

FIG. 1 is an example of the present invention (test numbers 3, 4, 11 and 1).
2) and the comparative example (test number 14) show the results of the Izod impact test.

Claims (8)

[Claims] 1. A polymer reaction product comprising (A) a polyolefin, (B) a polyvinyl alcohol having a mercapto group at the terminal, and (C) a monomer that can be graft-reacted with a polyolefin and that can react with a mercapto group, The above (A) polyolefin and the above (C) monomer graft reaction product
(B) A composite polymer having both hydrophobicity and hydrophilicity, which is obtained by reacting a mercapto group of polyvinyl alcohol. 2. The combination of hydrophobicity and hydrophilicity according to claim 1, wherein (A) 2 to 98 parts by weight of polyolefin and (B) 98 to 2 parts by weight of polyvinyl alcohol having a mercapto group at the end are used. Composite polymer to do. 3. (C) A monomer which can be graft-reacted with polyolefin and which can react with a mercapto group is a vinyl monomer having an epoxy group and a monomer having two vinyl groups in one molecule. A composite polymer having both hydrophobicity and hydrophilicity according to claim 1, which is selected. 4. A monomer (D) which is capable of grafting a mixture of (A) a polyolefin and (B) a polyvinyl alcohol having a mercapto group at its terminal to (C) a polyolefin and which can react with a mercapto group and (D) an organic compound. By melt-kneading with a peroxide, the graft reaction of the (A) polyolefin and the (C) monomer and the mercapto group of the (B) polyvinyl alcohol and the (C) monomer are reacted. A method for producing a composite polymer having both hydrophobicity and hydrophilicity. 5. A polyolefin graft reaction product obtained by melt-kneading (A) a polyolefin with (C) a polyolefin capable of graft reaction and a mercapto group-reactive monomer and (D) an organic peroxide. , (B)
A method for producing a composite polymer having both hydrophobicity and hydrophilicity, which comprises melt-kneading polyvinyl alcohol having a mercapto group at the terminal to react the mercapto group. 6. The hydrophobicity and hydrophilicity according to claim 4, wherein (A) 2 to 98 parts by weight of polyolefin and (B) 98 to 2 parts by weight of polyvinyl alcohol having a mercapto group at the end are used. A method for producing a composite polymer that combines the two. 7. (C) A monomer which can be graft-reacted with a polyolefin and which can react with a mercapto group is a vinyl monomer having an epoxy group or a monomer having two vinyl groups in one molecule. The method for producing a composite polymer having both hydrophobicity and hydrophilicity according to claim 4 or 5, which is selected. 8. A thermoplastic polymer composition obtained by melt-kneading a mixture of a polyolefin and polyvinyl alcohol with the composite polymer having both hydrophobicity and hydrophilicity according to any one of claims 1 to 3.