WO2007120414A1

WO2007120414A1 - Liquid transport film

Info

Publication number: WO2007120414A1
Application number: PCT/US2007/006160
Authority: WO
Inventors: Naoyuki Toriumi; Jiro Hattori; Shoichi Masuda
Original assignee: 3M Innovative Properties Company
Priority date: 2006-04-11
Filing date: 2007-03-12
Publication date: 2007-10-25
Also published as: JP2007277474A

Abstract

A liquid transport film comprising a base material and plural fine grooves for controlling a flow direction of a liquid formed on the main surface of the base material, wherein the base material is made of a mixture containing a polyolefin resin (A) and a polymer having a polyoxyethylene chain (B).

Description

LIQUID TRANSPORT FILM

FIELD

The present invention relates to a liquid transport film which transports while controlling a flow direction of a liquid.

BACKGROUND

It is known that a liquid transport film is useful for transportation of various liquids such as blood, body fluid, urine, alcohol, water and ink, and the liquid transport film is used for medical applications such as surgical operation, dental treatment and specimen test, and is also used in trays for food, diapers, and the heads of ink-jet printers.

In a conventional liquid transport film, a material prepared by incorporating a surfactant into a polyolefin material is mainly used. The polyolefin material is excellent in chemical resistance and water resistance and is cheap and flexile and is also excellent in processability, and is therefore useful as a base material of the liquid transport film. The surfactant has the effect of enhancing surface energy so as to transport a liquid having high polarity on the surface of the polyolefin film.

However, in case of a conventional liquid transport film containing a surfactant, although desired liquid transporting properties can be obtained in the initial stage, deterioration of transporting properties of the liquid having high polarity is recognized during continuous use or in applications where the liquid transport film is continuously contacted with the liquid. This reason is considered as follows. That is, the surfactant is merely incorporated and does not form a firm bond (for example, covalent bond) with the polyolefin material, and the surfactant is dissociated in the liquid to be transported. When surfactant is gradually dissociated in the liquid, the liquid to be transported or a member to be contacted with the liquid may be deteriorated. For example, it is known in the medical field that blood cells are broken down by a certain kind of a surfactant, and the use of the liquid transport film is limited in applications for specimen test. In the field of the ink-jet printer, when used in the inner surface of an ink tank or a member in the vicinity of a head, there is a fear that the surfactant is migrated to the ink or member to be contacted, thereby to vary the surface tension and printability.

Therefore, in these fields, the use of a higher molecular weight hydrophilic resin as a substitute for the surfactant is required. However, there is a problem that a conventional hydrophilic resin is inferior in compatibility with a polyolefϊn material and therefore deteriorates mechanical strength and transparency of the polyolefϊn material when incorporated. In the field of the medical specimen, transparency is an important essential element because it is necessary to transmit a liquid transport film constituting a microchannel and to detect through an optical action.

SUMMARY

The present invention provides a liquid transport film made of a mixture containing:

(A) a polyolefin resin, and

(B) a polymer having a polyoxyethylene chain, said liquid transport film comprising plural fine grooves for controlling a flow direction of a liquid on the main surface. The liquid transport film of the present invention exhibits high liquid transport ability without lowering transparency and mechanical strength of a polyolefin material by adding a polymer having a polyoxyethylene chain to the polyolefin material in place of a surfactant. .

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a sectional view showing an aspect of the shape of a groove on a liquid transport film of the present invention.

Fig. 2 is a sectional view showing an aspect of the shape of a groove on a liquid transport film of the present invention. Fig. 3 is a sectional view showing an aspect of the shape of a groove on a liquid transport film of the present invention.

Fig. 4 is a sectional view showing the shape of a liquid transport film produced in examples.

DETAILED DESCRIPTION

The liquid transport film of the present invention comprises a base material and plural fine grooves for controlling a flow direction of a liquid formed on the main surface of the base material, wherein the base material is made of a mixture containing a polyolefin resin (A) and a polymer having a polyoxyethylene chain (B).

The polyolefin resin (A) constituting the main component of the base material is excellent in chemical resistance and water resistance and is cheap and flexible, and is also excellent in processability, and is therefore useful as a base material of a liquid transport film. Examples of the polyolefin resin include polyethylene, polypropylene, propylene- ethylene copolymer, polybutene and polymethylpentene-1. Among these resins, polyethylene and polypropylene are particularly preferable taking account of processability and mechanical properties. This polyolefin resin preferably has a melt flow rate (MFR) of 1 to 500 taking account of processability. When MFR is less than 1, processing accuracy may deteriorate, thereby making it difficult to form into a thin film. On the other hand, when MFR is more than 500, mechanical strength of the film may decrease. This MFR is a value as measured in accordance with JIS K67581 (load of 2.16 kgf at 230⁰C in case of polypropylene, load of 2.16 kgf at 190⁰C in case of polyethylene). ^v

Furthermore, the polyolefin resin may be copolymerized with a hydrophilic monomer such as carboxylic acid, hydroxyl group or amino group, or an acrylate ester during polymerization of a monomer such as ethylene or propylene so as to improve flexibility or adhesion as long as an adverse influence is not exerted on properties suited for use as a liquid transport film.

To the polyolefin resin (A), a polymer having a polyoxyethylene chain (B) is added as means for imparting hydrophilicity. Examples of the polymer having a polyoxyethylene chain (B) include a polyetheresteramide (Bl), a block copolymer (B2) having a structure that a block of a polyolefin (a) and a block of a polymer having a polyoxyethylene chain (b) are alternately and repeatedly bonded via at least one bond selected from the group consisting of ester bond, amide bond, ether bond and imide bond, a polyetheramideimide (B3), an epihalohydrin-alkylene oxide copolymer (B4). a polyetherester (B5), a methoxypolyethylene glycol (meth)acrylate copolymer (B6), a polyether group-containing ethylene- vinyl acetate copolymer (B 7), and a mixture of two or more kinds of these polymers.

Examples of the polyetheresteramide (Bl) include polyetheresteramides described in Japanese Unexamined Patent Publication (Kokai) Nb. 6-287547 and Japanese Examined Patent Publication (Kokoku) No. 4-5691. Among these, polyetheresteramide derived from a polyamide (Bl 1) having a number average molecular weight (Mn) as measured by GPC (gel permeation chromatography) method of 200 to 5,000 and an alkylene oxide adduct (B 12) of a bisphenol compound having Mn of 300 to 5,000 is preferable in view of heat resistance.

Examples of the polyamide (Bl 1) include (1) a lactam ring-opened polymer, (2) a polycondensate of aminocarboxylic acid and (3) a polycondensate of dicarboxylic acid and diamine. Among an amide-forming monomer constituting these polyamides, the lactam (1) includes lactam having 6 to 12 carbon atoms, for example, caprolactam, enantolactam, laurolactam or undecanolactam. The aminocarboxylic acid in (2) include an aminocarboxylic acid having 6 to 12 carbon atoms, for example, co-aminocaproic acid, ω- aminoenanthic acid, ω-aminocaprylic acid, ω-aminopergonic acid, ω-aminocapric acid, 11-aminoundecanoic acid or 12-aminododecanoic acid. Examples of the dicarboxylic acid in (3) include an aliphatic dicarboxylic acid, an aroma (aliphatic) dicarboxylic acid, an alicyclic dicarboxylic acid, amide-forming derivatives thereof (for example, acid anhydride and lower (C1-C4) alkyl ester) and a mixture of two or more kinds of these acids.

Examples of the aliphatic dicarboxylic acid include those having 4 to 20 carbon atoms, for example, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecane diacid, dodecane diacid, maleic acid, fumaric acid and itaconic acid. Examples of the aroma (aliphatic) dicarboxylic acid include alkali metal (for example, sodium, potassium) salts of those having 8 to 20 carbon atoms, for example, ortho-, iso- and terephthalic acid, naphthalene-2,6- and -2,7-dicarboxylic acid, diphenyl- 4,4' dicarboxylic acid, diphenoxyethanedicarboxylic acid and 3-sulfoisophthalic acid. Examples of the alicyclic dicarboxylic acid include those having 7 to 14 carbon atoms such as cyclopropanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, cyclohexenedicarboxylic acid and dicyclohexyl-4,4-dicarboxylic acid.

Examples of the acid anhydride of the amide-forming derivative include anhydrides of the above dicarboxylic acids, for example, maleic anhydride, itaconic anhydride and phthalic anhydride, and examples of the lower (Cl -C4) alkyl ester include lower alkyl esters of the above dicarboxylic acids, for example, dimethyl adipate, and dimethyl ortho-, iso- and terephthalate. Examples of the diamine include those having 6 to 12 carbon atoms, for example, examethylenediamine, heptamethylenediamiiie, octamethylenediamine and decamethylenediamine.

. Those exemplified as the amide-forming monomer may be used in combination. Among these, caprolactam, 12-aminododecanoic acid and adipic acid/hexamethylenediamine are preferable, and caprolactam is particularly preferable, in view of the obtainment of hydrophilicity.

The polyamide (Bl 1) is obtained by ring-opening polymerization or polycondensation of the above amide-forming monomer according to a conventional method in the presence of at least one dicarboxylic acid having 4 to 20 carbon atoms as a molecular weight modifier. Examples of the dicarboxylic acid having 4 to 20 carbon atoms include those exemplified in (3). Among these, aliphatic dicarboxylic acid, aromatic dicarboxylic acid and 3-sulfoisophthalic acid alkali metal salts are preferable, and sodium adipate, sebacate, terephthalate, isophthalate and.3-sulfoisophthalate are more preferable, in view of the obtainment of hydrophilicity. The amount of the molecular weight modifier is preferably form 2 to 80% by weight, and more preferably from 4 to 75% by weight, based on the total mass of the amide-forming monomer and the molecular weight modifier in view of hydrophilicity and heat resistance.

Mn of the polyamide (Bl 1) is preferably from 200 to 5,000, and more preferably from 500 to 3,000, in view of reactivity and heat resistance of the resulting polyetheresteramide (Bl).

Examples of the bisphenol compound constituting the alkylene oxide adduct (B 12) of the bisphenol compound in the present invention include those having 13 to 20 carbon atoms, for example, bisphenol A, bisphenol F and bisphenol S. Among these compounds, bisphenol A is preferable in view of dispersibility.

Examples of the alkylene oxide to be added to the bisphenol compound include those having 2 to 12 carbon atoms, for example, ethylene oxide, propylene oxide, 1,2-, 2,3- and 1,4-butylene oxide; and epoxidated α-olefin haying 5 to 12 carbon atoms, styrene oxide and epihalohydrin (for example, epichlorohydrin and epibromohydrin), and a mixture of two or more kinds of them. Among these, ethylene oxide is preferable in view of the obtainment of hydrophilicity.

Mn of the alkylene oxide adduct (B 12) of the bisphenol compound is preferably from 300 to 5,000, and more preferably from 500 to 4,000, in view of the obtainment of hydrophilicity.

The content of the alkylene oxide adduct (B 12) is preferably from 20 to 80% by weight, and more preferably from 30 to 70% by weight, based on the total mass of the polyamide (Bl 1) and the alkylene oxide adduct (B 12) in view of the obtainment of hydrophilicity of the polyetheresteramide (Bl), and heat resistance.

Specific examples of the method for preparing the polyetheresteramide (Bl) include, but are not limited to, the following Methods (1) and (2): Method (1): a method comprising the steps of reacting an amide-forming monomer with a dicarboxylic acid (molecular weight modifier) to form a polyamide (Bl 1), adding an alkylene oxide adduct (B 12) to the polyamide and polymerizing the mixture at high temperature (160 to 270⁰C) under reduced pressure (0.03 to 3 kPa); and Method (2): a method comprising the steps of simultaneously charging an amide- forming monomer, a dicarboxylic acid (molecular weight modifier) and an alkylene oxide adduct (B 12) in a reaction vessel, reacting them at high temperature (160 to 270⁰C) under pressure (0.1 to 1 MPa) in the presence or absence of water to form an intermediate polyamide (Bl 1) and polymerizing the intermediate polyamide with an alkylene oxide adduct (B 12) under reduced pressure (0.03 to 3 kPa).

Among these methods, the Method (1) is preferable in view of control of the reaction.

As the method for preparing the polyetheresteramide (Bl), there may be used a method comprising the steps of substituting a terminal hydroxyl group of the alkylene oxide adduct (B 12) with an amino group or a carboxyl group and reacting with a polyamide having a carboxyl group or an amino group at end, in addition to the above methods. Examples of the method of substituting the terminal hydroxyl group of the alkylene oxide adduct (B 12) with the amino group include known methods, for example, a method of reducing a terminal cyanoalkyl group obtained by cycloalkylating a hydroxyl group to an amino group (for example, a method of reacting an alkylene oxide adduct (B 12) with an acrylonitrile and hydrogenating the resulting cyanoethylated compound). Examples of the method of substituting the terminal hydroxyl group of the alkylene oxide adduct (B 12) with the carboxyl group include a method of oxidizing with an oxidizing agent (for example, a method of oxidizing the hydroxyl group of the alkylene oxide adduct (B 12) with a chromic acid).

In the polymerization reaction, conventionally known esterification catalysts are used. Examples of the catalyst include antimony catalyst (for example, antimony trioxide), tin catalyst (for example, monobutyltin oxide), titanium catalyst (for example, tetrabutyl titanate), zirconium catalyst (for example, tetrabutyl zirconate) and acetic acid metal salt catalyst (for example, zinc acetate, zirconyl acetate). The amount of the catalyst is preferably from 0.1 to 5% by weight, and more preferably from 0.2 to 3% by weight, based on the total mass of the polyetheresteramide (Bl 1) and the alkylene oxide adduct (B 12) in view of reactivity and physical properties of the resin. Reduced viscosity [η_sp/C, C = 0.5% by weight (m-cresol solution, 25°C), value measured by using a viscometer Ubbelohde IA, unit is dl/g, the same shall apply hereinafter] of the polyetheresteramide (Bl) is preferably from 0.5 to 4, and more preferably from 0.6 to 3 in view of heat resistance of the polyetheresteramide (Bl) and moldability of the resin composition. Hereinafter, the reduced viscosity is indicated only by a numerical value.

As the block polymer (B2), block polymers described in the specification of WO 00/47652 can be used. As the block of the polyolefin (a), a polyolefin (a21) having a carbonyl group (preferably, carboxyl group), a hydroxyl group and an amino group at both ends of the polymer can be used. Examples of the polyolefin (a21) include those obtained by preferably introducing a carbonyl group into both ends of a polyolefin (a20) containing a polyolefin, both ends of which can be modified, as the main component (the content of preferably 50% by weight or more, more preferably 75% by weight or more, and particularly preferably 80 to 100% by weight or more). The polyolefin (a20) is usually a mixture of a polyolefin, both ends of which can be modified, a polyolefin, one end of which can be modified, and a polyolefin which has not a terminal group that can be modified, but those having the polyolefin, both ends of which can be modified, as the main component are preferable.

As the polyolefin (a20), there can be used a polyolefin [obtained by the polymerization method] obtained by (co)polymerization (which means polymerization or copolymerization, the same shall apply hereinafter) of a mixture of one or more kinds of olefins having 2 to 30 carbon atoms, and a low molecular weight polyolefin [obtained by the thermal degradation method] obtained from a higher molecular weight polyolefin (polyolefin obtained by polymerization of an olefin having 2 to 30 carbon atoms) using the thermal degradation method.

Examples of the olefin having 2 to 30 carbon atoms include ethylene, propylene, α-olefin having 4 to 30 (preferably 4 to 12, and more preferably 4 to 10) carbon atoms, and diene having 4 to 30 (preferably 4 to 18, and more preferably 4 to 8) carbon atoms. Examples of the α-olefin having 4 to 30 carbon atoms include 1-butene, 4-methyl-l- pentene, 1-pentene, 1-octene, 1-decene and 1-dodecene; and examples of the diene include butadiene, isoprene, cyclopentadiene and 1,11-dodecadiene. The olefin is preferably an olefin having 2 to 12 carbon atoms (for example, ethylene, propylene, α-olefin having 4 to 12 carbon atoms, butadiene and/or isoprene), more preferably an olefin having 2 to 10 carbon atoms (for example, ethylene; propylene, α-olefin having 4 to 10 carbon atoms and/or butadiene), and particularly preferably ethylene, propylene and/or butadiene.

The low molecular weight polyolefin obtained by the thermal degradation method can be easily obtained, for example, by the meted described in Japanese Unexamined Patent Publication (Kokai) No. 3-62804. The polyolefin obtained by the polymerization method can be prepared by a known method and can be easily obtained, for example, by the method for (co)polymerization of the above olefin in the presence of a radical catalyst, a metal oxide catalyst, a Ziegler catalyst or a Ziegler-Natta catalyst.

Examples of the radical catalyst include known ones, for examples, di-t-butyl peroxide, t-butyl benzoate, decanol peroxide, lauryl peroxide, peroxy-di-carbonate ester, azo compound, and those obtained by coating a γ-alumina carrier with molybdenum oxide. Examples of the metal oxide catalyst include those obtained by coating a silica-alumina carrier with chromium oxide. Examples of the Ziegler catalyst and Ziegler-Natta catalyst include (C₂Hs)₃Al-TiCl₄. In view of ease of introduction of a carbonyl group as a modifying group and availability, a low molecular weight polyolefin obtained by the thermal degradation method is preferable.

Mn of the polyolefin (a20) is preferably from 800 to 20,000, more preferably from 1,000 to 10,000, and particularly preferably from 1,200 to 6,000, in view of the obtainment of hydrophilicity. The number of double bonds in the polyolefin (a20) is preferably from 1 to 40, more preferably from 2 to 30, and particularly preferably from 4 to 20, based on 1,000 carbon atoms in view of the obtainment of hydrophilicity. The average number of double bonds per molecule is preferably from 1.1 to 5, more preferably from 1.3 to 3, particularly preferably from 1.5 to 2.5, and most preferably from 1.8 to 2.2, in view of forming properties of a repeated structure and hydrophilicity. In the thermal degradation method, there can be easily obtained a low molecular weight polyolefin which has Mn within a range from 800 to 6,000 and average number of terminal double bonds within a range from 1.5 to 2 [see, for example, Katsuhide MURATA, Tadahiko MAKINO, Nippon Kagaku Kaishi, pp.192 (1975)].

Conditions for measurement of Mn are as follows (Mn is measured under the same conditions hereinabove and hereinafter). Apparatus: High temperature gel permeation chromatography Solvent: Orthodichlorobenzene

Reference material: Polystyrene

Sample concentration: 3 mg/ml

Column stationary phase: PLgel MIXED-B Column temperature: 135°C . Examples of the polyolefin (a21) having a carbonyl group at both ends of the polymer include polyolefin (a21 1) having a structure in which both ends of a polyolefin (b20) are modified with an α,β -unsaturated carboxylic acid (anhydride) (α,β-unsaturated carboxylic acid, its alkyl ester having 1 to 4 carbon atoms, or its anhydride, the same shall apply hereinafter); polyolefin (a212) having a structure in which the polyolefin (a211) is secondary-modified with lactam or amino carboxylic acid; polyolefin (a213) having a structure in which a polyolefin (a20) is oxidized or hydroformylated; polyolefin (a214) having a structure in which a polyolefin (a213) is secondary-modified with lactam or aminocarboxylic acid; and a mixture of two or more kinds of these polyolefins.

The polyolefin (a211) is obtained by modifying a polyolefin (a20) with an α,β- unsaturated carboxylic acid (anhydride). Examples of the α,β-unsaturated carboxylic acid (anhydride) include carboxylic acids having 3 to 12 carbon atoms, for example, monocarboxylic acid [for example, (meth)acrylic acid], dicarboxylic acid (for example, maleic acid, fumaric acid, itaconic acid, citraconic acid), alkyl (C1-C4) ester thereof [for example, (meth)methyl acrylate, butyl (meth)acrylate, diethyl itaconate], and anhydride thereof. In view of reactivity with the polyolefin (a20), the polyolefin is preferably dicarboxylic acid, alkyl ester and anhydride thereof, more preferably maleic acid (anhydride) and fumaric acid, and particularly preferably maleic acid (anhydride). The amount of the α,β-unsaturated carboxylic acid (anhydride) is preferably from 0.5 to 40% by weight, more preferably from 1 to 30% by weight, and particularly preferably from 2 to 20% by weight, based on the mass of the polyolefin (a20) in view of forming properties of the repeated structure and hydrophilicϊty. Modification of the polyolefin (a20) with the α,β-unsaturated carboxylic acid (anhydride) can be conducted by a known method, for example, a method of thermally adding the α,β-unsaturated carboxylic acid (anhydride) to a terminal double bond of the polyolefin (a20) using a solution method or a fusion method (ene reaction). The solution method include a method comprising the steps of adding the α,β-unsaturated carboxylic acid (anhydride) to the polyolefin (a20) in the presence of a hydrocarbon-based solvent such as xylene or toluene, and reacting in an inert gas atmosphere such as nitrogen at 170 to 230⁰C. The fusion method includes a method comprising the steps of thermally fusing the polyolefin (a20), adding the α,β-unsaturated carboxylic acid (anhydride), and reacting in an inert gas atmosphere such as nitrogen at 170 to 230⁰C. Among these methods, a solution method is preferable in view of uniformity of the reaction.

The polyolefin (a212) is obtained by secondary modifying of a polyolefin (a211) with lactam or aminocarboxylic acid. Examples of the lactam include lactams having 6 to 12 (preferably 6 to 8, and more preferably 6) carbon atoms, for example, caprolactam, enantolactam, laurolactam and undecanolactam. Examples of the aminocarboxylic acid include aminocarboxylic acids having 2 to 12 (preferably 4 to 12, and more preferably 6 to 12) carbon atoms, for example, amino acid (for example, glycine, alanine, valine, leucine, isoleucine, phenylalanine), ω-aminocaproic acid, ω-aminoenanthic acid, ω-aminocaprylic acid, ω-aminopergonic acid, ω-aminocapric acid, 11-aminoundecanoic acid and 12- aminododecanoic acid. In view of reactivity of secondary modification, the lactam is preferably caprolactam, laurolactam, glycine, leucine, ω-aminocaprylic acid, 11- aminoundecanoic acid or 12-aminododecanoic acid, more preferably caprolactam, laurolactam, ω-aminocaprylic acid, 11-aminoundecanoic acid or 12-aminododecanoic acid, and particularly preferably caprolactam or 12-aminododecanoic acid.

The polyolefin (a213) is obtained by hydroformylation of a polyolefin (a20) with oxygen and/or ozone using an oxidation or oxo method thereby to introduce a carbonyl group. Introduction of the carbonyl group through oxidation can be conducted by a known method, for example, the method described in the specification of U.S. Patent No. 3,692,877. Introduction of the carbonyl group through hydroformylation can be conducted by a known method, for example, the method described in Macromolecules, Vol. 31, pp.5943. The polyolefm (a214) can be obtained by secondary modification of a polyolefin

(a213) with lactam or aminocarboxylic acid. Examples of the lactam and aminocarboxylic acid include those exemplified in the alkylene oxide adduct (B 12) and also the amounts are the same.

Mn of the polyolefin (a21) having a carbonyl group at both ends is preferably from 800 to 25,000, more preferably from 1,000 to 20,000, and particularly preferably from 2,500 to 10,000, in view of heat resistance and reactivity with a hydrophilic polymer (b) described hereinafter. In view of reactivity with the hydrophilic polymer (b), the acid value of the polyolefin (a21) is preferably from 4 to 280 (mg KOH/g, only a numerical value is described hereinafter), more preferably from 4 to 100, and particularly preferably from 5 to 50.

As the polymer having a polyoxyethylene chain (b), a polyetherdiol (bl) and a polyetherdiamine (b2) can be used.

Examples of the polyetherdiol (bl) include those having a structure obtained by the addition reaction of a diol (bθl) or a dihydric phenol (bO2) with an alkylene oxide (C3- C 12) containing ethylene oxide as an essential component, for example, those represented by the general formula: H(OA¹)_mO-E¹-O(A^IO)_m-H. In the formula, E¹ represents a residue in which a hydroxyl group is eliminated from the diol (bθl) or the dihydric phenol (bO2), A¹ represents an alkylene group having 2 to 12 (preferably 2 to 8, and more preferably 2 to 4) carbon atoms which essentially has an alkylene group having 2 carbon atoms which may have a halogen atom, m and m' represent an integer of 1 to 300, preferably from 2 to 250, and particularly preferably from 10 to 100, and m and m¹ may be the same or different, m (OA¹) and m¹ (A¹O) may be the same or different. When these are composed of two or more kinds of oxyalkylene groups containing ethylene oxide as an essential component, bonding form may be block, random or a combination thereof. Examples of the diol (bθl) include dihydric alcohol (aliphatic, alicyclic and aroma- aliphatic dihydric alcohols) having 2 to 12 (preferably 2 to 10, and more preferably 2 to 8) carbon atoms and tertiary amino group-containing diol having 1 to 12 carbon atoms. Examples of the aliphatic dihydric alcohol include ethylene glycol, propylene glycol, 1,4- butane diol, 1,6-hexane diol, neopentyl glycol and 1,12-dodecane diol. Examples of the alicyclic dihydric alcohol include 1,4-cyclohexane diol, 1,4-cyclohexane dimethanol, 1,4- cyclooctane diol and 1 ,3-cyclopentane diol. Examples of the aroma-aliphatic dihydric alcohol include xylylene diol, 1 -phenyl- 1,2-ethane diol and l,4-bis(hydroxyethyl)benzene.

Examples of the tertiary amino group-containing diol include a bishydroxyalkylated (alkyl group having 1 to 12, preferably 2 to 10, and more preferably 2 to 8 carbon atoms) compound of an aliphatic or alicyclic primary monoamine (having 1 to 12, preferably 2 to 10, more preferably 2 to 8 carbon atoms), and a bishydroxyalkylated 0 (alkyl group having 1 to 12 carbon atoms) compound of an aroma (aliphatic) primary monoamine (having 6 to 12 carbon atoms). The bishydroxyalkylated compound of the monoamine can be easily obtained by a known method, for example, a method of reacting a monoamine with an alkylene oxide (for example, ethylene oxide, propylene oxide, butylene oxide) having 2 to 4 carbon atoms, or reacting a monoamine with a halogenated hydroxyalkyl (for example, 2-bromoethyl alcohol, 3-chloropropyl alcohol) having 1 to 12 carbon atoms.

Examples of the aliphatic primary monoamine include methylamine, ethylamine, 1- and 2-propylamine, n- and i-amylamine, hexylamine, 1,3-dimethylbutylamine, 3,3- dimethylbutylamine, 2- and 3-aminoheptane, heptylamine, nonylamine, decylamine, undecylamine and dodecylamine. Examples of the alicyclic primary monoamine include cyclopropylamine, cyclopentylamine and cyclohexylamine. Examples of the aroma (aliphatic) primary monoamine include aniline and benzylamine.

Examples of the dihydric phenol (bO2) include phenols having 6 to 18 (preferably 8 to 18, and more preferably 10 to 15) carbon atoms, for example, monocyclic dihydric phenol (for example, hydroquinone, catechol, resorcin, urushiol), bisphenol (for example, bisphenol A, bisphenol F, bisphenol S, 4,4' -dihydroxydiphenyl-2,2 -butane, dihydroxybiphenyl) and condensated polycyclic dihydric phenol (for example, dihydroxynaphthalene, binaphthol).

Among the diol (bθl) and the dihydric phenol (bO2), a dihydric alcohol and a ⁾ dihydric phenol are preferable, an aliphatic dihydric alcohol and a bisphenol are more preferable, and ethylene glycol and bisphenol A are particularly preferable in view of hydrophilicity. Examples of the alkylene oxide subjected to the addition reaction with the diol (bθl) or the dihydric phenol (bO2) include, in addition to ethylene oxide, alkylene oxide having 3 to 12 carbon atoms (propylene oxide, 1,2-, 1,4-, 2,3- and 1,3-butylene oxide and a mixture of two or more kinds of them) and, if necessary, the other alkylene oxide and substituted alkylene oxide may be used in combination. Examples of the other alkylene oxide and substituted alkylene oxide include an epoxidated compound of an α-olefm having 5 to 12 carbon atoms, styrene oxide and epihalohydrin (for example, epichlorohydrin and epibromohydrin). Each amount of the alkylene oxide and substituted alkylene oxide is preferably 30% by weight or less, more preferably from 0 or 25% by weight or less, and particularly preferably from 0 or 20% by weight or less, based on the - total mass of the alkylene oxide in view of the obtainment of hydrophilicity.

The addition mol number of the alkylene oxide is preferably from 1 to 300 mols, more preferably from 2 to 250 mols, and particularly preferably from 10 to 100 mols, based one hydroxyl group of the diol (bθl) or the dihydric phenol (bO2) in view of hydrophilicity of the polymer having a polyoxyethylene chain (b). When two or more kinds of alkylene oxides are used in combination, boning form may be random and/or block.

The addition reaction of the alkylene oxide can be conducted by a known method in the presence of an alkali catalyst (for example, potassium hydroxide, sodium hydroxide) under the conditions of a temperature of 100 to 200⁰C and a pressure of 0 to 0.5 MPaG.

The content of the oxyalkylene unit in the polyetherdiol (bl) is preferably from 5 to 99.8% by weight, more preferably from 8 to 99.6% by weight, and particularly preferably from 10 to 98% by weight, based on the mass of the polyetherdiol (bl) in view of hydrophilicity of the hydrophilic polymer (b). The content of the oxyethylene unit in the polyoxyalkylene chain is preferably from 5 to 100% by weight, more preferably from 10 to 100% by weight, particularly preferably from 50 to 100%, and most preferably from 60 to 100% by weight, based on the mass of the polyoxyalkylene chain in view of hydrophilicity of the hydrophilic polymer (b).

Examples of the polyetherdiamine (b2) include those having a structure in which a hydroxyl group of the polyetherdiol (bl) is modified to an amino group (primary or secondary amino group), for example, those represented by the general formula: RNH-A²- (OA')_mO-E¹-O(A¹O)_m-A²-NHR. Therefore, the content of the oxyethylene unit in the polyoxyalkylene chain is the same as in case of the polyetherdiol (bl), and the content of the oxyalkylene unit in the polyetherdiamine (b2) is the same as that of the oxyalkylene unit in the polyetherdiol (bl). In the formula, the symbol E¹ represents a residue in which a hydroxyl group is eliminated from the diol (bOl) or dihydric phenol (bO2), A¹ represents an alkylene group having 2 to 12 (preferably 2 to 8, more preferably 2 to 4) carbon atoms which may have a halogen atom, m and m¹ represent an integer of 1 to 300, preferably 2 to 250, and particularly preferably 10 to 100, and m and m¹ may be the same or different. A² represents an alkylene group having 2 to 12 (preferably 2 to 8, more preferably 2 to 4) carbon atoms which may have a halogen atom, and A¹ and A² may be the same or different and essentially have an alkylene group having 2 carbon atoms. R represents H or a C1-C4 (preferably 1 or 2) alkyl group. The polyetherdiamine (b2) can be easily obtained by converting both terminal hydroxyl groups of the polyetherdiol (bl) into amino groups by a known method. Examples of the method of converting the hydroxyl group into the amino group include known methods, for example, a method of reducing a terminal cyanoalkyl group obtained by cyanoalkylation of. a hydroxyl group of a polyetherdiol (bl) to an amino group (for example, a method of reacting a polyetherdiol (bl) with acrylonitrile and hydrogenating the resulting cyanoethylated compound), a method of reacting a polyetherdiol (bl) with aminocarboxylic acid or lactam, and a method of reacting a polyetherdiol (bl) with a halogenated amine under alkali conditions Two or more kinds of those exemplified as the polymer having a polyoxyethylene chain (b) may be optionally used in combination.

Mn of the polymer having a polyoxyethylene chain (b) is preferably from 150 to 20,000, more preferably from 300 to 18,000, particularly preferably from 1 ,000 to 15,000, and most preferably from 1,200 to 8,000, in view of heat resistance and reactivity with the polyolefϊn (a).

The block polymer (B2) has a structure in which a block of the polyolefin (a) and a block of a polymer having a polyoxyethylene chain (b) are alternately and repeatedly bonded via at least one bond selected from the group consisting of ester bond, amide bond, ether bond and imide bond. Among these polymers, a polymer having a repeating unit represented by the following general formula (1) is preferable in view of the obtainment of hydrophilicity. and transparency.

In the formula (1), n represents an integer of 2 to 50 (preferably 3 to 40, more preferably 4 to 30, and particularly preferably 5 to 25), one of R¹ and R² is H and the other is H or a methyl group, y represents an integer of 15 to 800 (preferably 20 to 500, and more preferably 30 to 400), E¹ represents a residue in which hydroxyl group is eliminated from a diol (b01) or a dihydric phenol (bO2), A¹ represents an ethylene group or an alkylene group having 2 to 4 carbon atoms which essentially has an ethylene group, m and m' represent an integer of 1 to 300 (preferably 5 to 200, and more preferably 8 to 150), X and X¹ represent a group selected from the following general formulas (2) and (3) as well as corresponding (T) and (3¹), that is, when X is a group represented by the general formula (2), X¹ is a group represented by the general formula (2'), and the same relation is established with respect to the general formulas (3) and (3¹).

A² -

X '

- Q ' - T ' -

Q ' - C H, -

In the general formulas (2), (3) as well as corresponding formulas (2¹) and (3¹), R is the same as that described in polyetherdiamine (b2) and represents H or a C1-C4 (preferably 1 or 2) alkyl group, R³ represents a divalent hydrocarbon group having 1 to 11 (preferably 2 to 11, more preferably 5 to 11), R⁴ represents H or an alkyl group having 1 to 10 (preferably 1 to 8, and more preferably 1 to 6) carbon atoms, r represents an integer of 1 to 20 (preferably 1 to 15, and more preferably 1 to 10), u represents 0 or 1 , and Q, Q', T and T' represent a group represented by the following formula.

Q : -CH₂- C = C- CH-

I I

I I (4) RR55 R R55 . ._

Q' : -CH = C -CH₂-

I I (4')

I I R 5 R S

O

T : Il

CH -(C H₂J t-

— M . _ N , .. ._.., ^c..

S CH (5)

C

Il \ R6

O

T T'' : • --( iCC H H₂J) t t--

R^B

In the general formulas (4) and (5) and corresponding formulas (4') and (5'), R⁵ represents H or an alkyl group having 1 to 10 (preferably 1 to 8, and more preferably 1 to 6) carbon atoms, R⁶ represents H or a methyl group, and t represents 1 when R⁶ is a methyl group and 0 when R⁶ is H. The polyether segment {(OA¹)_mO-E¹-O(A¹O)_m.} in the parenthesis {} in the repeating unit represented by the general formula (1) has a structure derived from the polyetherdiol (bl) or the polyetherdiamine (b2), and E¹, A¹, m and m' in the formulas are as defined above.

In the general formula (1), a block polymer in which X is a group represented by the general formula (2) and X' is a group represented by the general formula (2¹) contains (B21) obtained by polymerizing (a211) and/or (a212) with (bl), and (B22) obtained by polymerizing (a211) and/or (a212) with (b2). (B21) contains (B211) obtained by combination of (a211) and (bl), (B212) obtained by combination of (a212) and (bl), and a mixture of (B211 ) and (B212). Similarly, (B22) contains (B221 ) obtained by combination of (a211) and (b2), (B222) obtained by combination of (a212) and (b2), and a mixture of B221) and (B222).

(B21) can be prepared by a known method, for example, a method of adding (bl) to (a211) and/or (a212) and polymerizing (polycondensing) the mixture under reduced pressure at a temperature of preferably from 200 to 250⁰C, or a method of polymerizing under the conditions of a temperature of preferably from 160 to 250⁰C and a residence time of 0.1 to 20 minutes using a single- or twin-screw extruder. In the above polymerization reaction, there can be used known catalysts, for example, antimony catalyst (for example, antimony trioxide); tin catalyst (for example, monobutyltin oxide); titanium catalyst (for example, tetrabutyl titanate); zirconium catalyst (for example, tetrabutyl zirconate); organic acid metal salt catalyst [for example, zirconium organic acid salt (zirconyl acetate), zinc acetate]; and a mixture of two or more kinds of these catalyst. The catalyst is preferably a zirconium catalyst or a zirconium organic acid salt, and more preferably a zirconyl acetate. The amount of the catalyst is preferably from 0.001 to 5%, and more preferably from 0.01 to 3%, based on the total mass of (a211) and/or (a212) and (bl).

^' Among (B21), (B212) may be prepared by secondary modification of (a211) with lactam or aminocarboxylic acid, and reacting with (bl), or reacting (a211) with lactam or amϊnocarboxylic acid in the presence of (bl) and reacting with (bl). (B22) can be prepared in the same manner as in case of (B21), except that a combination of (a211) and/or (a212) and (bl) in (B21) is replaced by a combination of (a211) and/or (a212) and (b2). Among (B22), (B222) may be prepared by secondary modification of (b2) with the lactam or aminocarboxylic acid and reacting (a211).

In the general formula (1), a block polymer, in which X is a group represented by the general formula (3) and X¹ is a group represented by the general formula (3¹), contains (B23) obtained by the polymerization reaction of (a213) (when r = 1) and/or (a214) (when r > 2) and (bl) and (B24) obtained by the polymerization reaction of (a213) and/or (a214) and (b2). (B23) contains (B231) obtained by combination of (a213) and (bl), (B232) obtained by combination of (a214) and (bl), and a mixture of (B231) and (B232). Similarly, (B24) contains (B241) obtained by combination of (a213) and (b2), (B242) obtained by combination of (a214) and (b2), and a mixture of (B241) and (B242). (B23) and (B24) can be prepared in the same manner as in case of (B21) and (B22).

The amount of (b) constituting the block polymer (B2) is preferably from 20 to 90% by weight, more preferably from 25 to 80% by weight, and particularly preferably from 30 to 70% by weight, based on the total mass of (a) and (b) in view of the obtainment of hydrophilicity . Mn of the block polymer (B2) is preferably from 2,000 to 60,000, more preferably from 5,000 to 40,000, and particularly preferably from 8,000 to 30,000, in view of the obtainment of hydrophilicity.

In the structure of the block polymer (B2), the average repeating number (Nn) of a repeating unit of a block of a polyolefin (a) and a block of a polymer having a polyoxyethylene chain (b) is preferably from 2 to 50, more preferably from 2.3 to 30, . particularly preferably from 2.7 to 20, and most preferably from 3 to 10, in view of the obtainment of hydrophilicity. Nn can be determined by Mn of (B2) and ¹H-NMR analysis. In case of (B21 ) having a structure in which a block of (a211 ) and a block of (bl) are alternately and repeatedly bonded, a signal attributed to proton of an ester bond {- C(C=O)-OCH₂-) of 4.0 to 4.1 ppm and a signal attributed to proton of polyethylene glycol of 3.2 to 3.7 ppm can be observed in ¹H-NMR analysis, and therefore Nn can be determined from a ratio of proton integrated values of them and Mn.

The end of the block polymer (B2) may be any of a carbonyl group derived from the polyolefin (a), an amino group and/or non-modified polyolefin end (non-modified polyolefin end, that is, an alkyl group or an alkenyl group), a hydroxyl group derived from a polymer (b) having a polyoxyethylene chain and/or an amino group. In view of reactivity, the end is preferably a carbonyl group, an amino group or a hydroxyl group, and more preferably a carbonyl group or a hydroxyl group.

Examples of the polyetheramideimide (B3) include polyetheramideimides having a polyoxyethylene chain among those described in Japanese Examined Patent Publication (Kokoku) No. 7-119342 and Japanese Unexamined Patent Publication (Kokai) No. 06- 172609. Among these, preferred one is polyetheramideimide having a (b33) content of 30 to 85% by weight and reduced viscosity of 1.5 to 4 at 30⁰C, which is derived from a caprolactam (b31), a trihydric or tetrahydric aromatic polycarboxylic acid (b32) capable of reacting with an amino group to form at least one imide ring, and a mixture (b33) of polyethylene glycol or at least 50% by weight of polyethylene glycol and a polyalkylene glycol other than polyethylene glycol in view of heat resistance.

(b32) contains a trihydric or tetrahydric aromatic polycarboxylic acid capable of reacting with an amino group to form at least one imide ring and an acid anhydride thereof. Examples of the trihydric aromatic polycarboxylic acid include those having 9 to 18 carbon atoms, for example, 1 ,2,4-trimellitic acid, 1,2,5-naphthalenetricarboxylic acid, 2,6,7-naphthalenetricarboxylic acid, 3,3',4-diphenyltricarboxylic acid, benzophenone- 3,3',4-tricarboxylic acid, diphenylsulfon-3,3',4-tricarboxylic acid, diphenylether-3,3',4- tricarboxylic acid, and an acid anhydride thereof. Examples of the tetrahydric aromatic polycarboxylic acid include those having 10 to 20 carbon atoms, for example, pyromellitic acid, diphenyl-2,2\3,3'-tetracarboxylic acid, benzophenone-2,2',3,3'-tetracarboxylic acid, diphenylsulfon-2,2',3,3'-tetracarboxylic acid, diphenylether-2,2',3,3'-tetracarboxyHc acid, and an acid anhydride thereof.

(b33) contains a mixture of polyethylene glycol or at least 50% by weight of polyethylene glycol, and a polyalkylene glycol other than polyethylene glycol.

Mn of the polyethylene glycol is not specifically limited and is preferably from 500 to 5,000, and more preferably from 800 to 3,000, in view of the obtainment of hydrophilicity of the polyetheramideimide (B3), and production.

Examples of the polyalkylene glycol other than polyethylene glycol (alkylene has 3 to 18 carbon atoms) those having Mn of 500 to 5,000, for example, polypropylene glycol, polytetramethylene glycol and modified polyalkylene glycol. Examples of the modified polyalkylene glycol include at least two kinds of addition polymers among alkylene oxides having 2 to 10 carbon atoms (addition form may be random or block). Among these alkylene oxides, ethylene oxide, propylene oxide, 1,3-propylene oxide, 2-methy 1-1,3 - propylene oxide, 2,2-dimethyl- 1,3 -propylene oxide, 1,5-pentamethylene oxide and 1,6- hexamethylene oxide are preferable in view of the obtainment of hydrophilicity. An equivalent ratio in the reaction between (b32) and glycol (b33) is preferably from 0.9/1 to 1.1/1, and is more preferably from 0.95/1 to 1.05/1, in terms of molar ratio in view of physical properties of the resin. The content of the polyamideimide constituting the polyetheramideimide (B3) is preferably from 15 to 70% by weight, and more preferably from 30 to 65% by weight, in view of the obtainment of hydrophilicity of (B3), and water resistance of a molded article. Mn of the polyamideimide moiety in the polyetheramideimide (B3) is preferably from 500 to 3,000, and more preferably from 800 to 2,000, in view of heat resistance of (B3) and mechanical strength of the molded article.

Examples of the method for preparing the polyetheramideimide (B3) include, but are not limited to, the followings. That is, it is a method of mixing (b31), (b32) and (b33) so that an equivalent ratio of (b32) to (b33) is preferably from 0.9 to 1.1 (more preferably from 0.95 to 1.05) and the amount of (b33) is preferably from 30 to 85% by weight, and more preferably from 35 to 70% by weight, based on the total mass of (b31), (b32) and (b33) in .view of the obtainment of hydrophilicity, and polycondensing the mixture at a temperature of preferably 150 to 300⁰C, and more preferably 180 to 280⁰C, while maintaining a moisture content of the resulting polymer within a range from 0.1 to 1% by weight. In case of the polycondensation, the reaction temperature can be raised stepwise. In this case, a portion of the caprolactam is remained without being reacted and is preferably removed from the reaction mixture by distillation under reduced pressure in view of physical properties of the resin of the molded article. After removing the unreacted caprolactam, the reaction mixture can be optionally converted into a higher molecular weight polymer by polymerizing under reduced pressure (0.03 to 3 kPa), at preferably 200 to 300⁰C (more preferably 230 to 280⁰C).

In view of moldability of the resin composition, reduced viscosity of the polyetheramideimide (B3) is preferably from 1.5 to 4, and more preferably from 1.7 to 3.5. Examples of the epihalohydrin-alkylene oxide copolymer (B4) include an epihalohydrin-alkylene oxide copolymer having a polyoxyethylene chain among those described in Japanese Examined Patent Publication (Kokoku) No. 7-84564. Examples of the epihalohydrin include epichlorohydrin, epibromohydrin, epiiodohydrin and epifluorohydrin. In view of reactivity and cost, epichlorohydrin is preferable. Examples of the alkylene oxide include those having 2 to 4 carbon atoms, for example, ethylene oxide, propylene oxide and tetrahydrofuran.

The epihalohydrin-alkylene oxide copolymer (B4) includes a copolymer of epihalohydrin and one or more comonomers selected from 1 ,2-epoxide monomer (particularly, alkyl (C2-C4) glycidyl ether) and alkylene oxide (particularly, ethylene oxide and propylene oxide). A mass ratio of epihalohydrin to alkylene oxide is usually from 5/95 to 95/5, and is preferably from 10/90 to 60/40 in view of the obtainment of hydrophilicity. The content of the oxyethylene unit in the polyoxyalkylene chain is preferably from 5 to 100% by weight, and more preferably from .10 to 100% by weight.

Among the epihalohydrin-alkylene oxide copolymer (B4), a copolymer of epichlorohydrin-ethylene oxide (mass ratio: 50/50) is preferable so as to impart physical properties of the resin and hydrophilicity. ,

The epihalohydrin-alkylene oxide copolymer (B4) can be easily prepared by the bulk polymerization or solution polymerization using a known catalyst, for example, an organic aluminum compound (for example, triethyl aluminum), or using a catalyst obtained by reacting an organic aluminum compound with water so as to improve polymerizability. A ratio of water to the organic aluminum compound (water/organic aluminum compound) is usually from 0.1/1 to 1/1, and preferably from 0.3/1 to 0.7/1, in view of polymerizability. Mn of the epihalohydrin-alkylene oxide copolymer (B4) is preferably from 30,000 to 100,000, and more preferably from 60,000 to 90,000, in view of physical properties of the resin and moldability.

Examples of the polyetherester (B5) include polyetherester having a polyoxyethylene chain among those described in Japanese Examined Patent Publication (Kokoku) No. 58-19696. The polyetherester (B5) is a polyester having a segment made of polyetherdiol or copolyetherdiol and is obtained, for example, by the polycondensation reaction of the polyetheresteramide (Bl) or at least one of (bl2) and (a33) exemplified as the constituent component of the polyetheramideimide (B3), and at least one of dicarboxylic acid exemplified as the constituent component of (Bl) and a ester-forming derivative thereof (for example, lower (C1-C4) alkyl ester, acid anhydride), or the ester exchange reaction of the above diol component and polyethylene terephthalate or polybutylene terephthalate.

The content of the polyether segment of the polyetherester (B5) is preferably from 30 to 70% by weight, and more preferably from 40 to 60% by weight, in view of the obtainment of hydrophilicity of (B5), and moldability of the resin composition. The melting point (measured by differential scanning calorimetry (hereinafter abbreviated to DSC) of (B 5) is preferably 100⁰C or higher, and more preferably from 120 to 210⁰C, in view of heat resistance. The content of the oxyethylene unit in the polyoxyalkylene chain is preferably from 5 to 100% by weight, and more preferably from 10 to 100% by weight.

In addition to the polyolefin resin (A) and the polymer having a polyoxyethylene chain (B), stabilizers such as antioxidants and ultraviolet absorbers, processing aids, lubricants, pigments, sensitizers for enhancing internal crosslinking, and fillers such as inorganic substances may be added as long as required properties such as liquid transporting properties, transparency, mechanical strength and hard-to-dissociate are not adversely affected.

The polyolefin resin (A), the polymer having a polyoxyethylene chain (B) and, if necessary, various additives are melt-fused and a disperse phase of the polymer having a polyoxyethylene chain (B) is dispersed in a continuous phase of the polyolefin resin (A). Although a ratio of the amount of polyolefin resin (A) and that of the polymer having a polyoxyethylene chain (B) varies depending on the material to be used, the amount of the polyolefin resin (A) is preferably from 70 to 85% by weight of and the amount of the polymer having a polyoxyethylene chain (B) is preferably from 30 to 15% by weight.

When the amount of the polymer having a polyoxyethylene chain (B) is more than 30% by weight, swelling or deformation may occur because of too high hydrophilicity of the liquid transport film. On the other hand, when the amount is less than 15% by weight, sufficient hydrophilicity can not be obtained and the liquid transporting effect is not exerted. More preferably, the amount of the polymer having a polyoxyethylene chain (B) is from 30 to 20% by weight.

Examples of the melt-mixing method include a conventional method, for example, a method of mixing palletized or powdered polymers using a proper mixer such as Henshel mixer and melt-kneading the polymers using an extruder. The kneading time is preferably from 0.1 to 10 minutes, and more preferably from 1 to 7 minutes. When the kneading time is 0.1 minutes or more, kneading is sufficiently conducted. On the other hand, when the kneading time is 10 minutes or less, the resin hardly deteriorates. The kneading temperature is the melting point of the components (A) and (B) or higher, and is preferably 280⁰C or lower. When the kneading temperature is 280⁰C or lower, the resin hardly deteriorates.

The liquid transport film of the present invention is provided with plural fine grooves for controlling a flow direction of a liquid on at least one of main surfaces. Plural fine grooves are formed by molding or embossing. The shape of the groove may be any shape as long as it can transport a liquid along an axis direction of the groove. For example, the shape of the groove is a V-shape, a rectangular shape, or a combination of them, or may be shape in which a second groove is included in a first groove. The shape of a groove will be described with reference to the accompanying drawings. As shown in Fig. 1, grooves 13 are formed on a polyolefin base material 14 by a series of V-shaped side walls 11 and tip sections 12. As shown in Fig. 2, wide and flat root sections 22 may be formed between slightly flattened tip sections 21 to form grooves 23. The depth of the grooves (that is, the distance from tip to bottom) is generally from 5 to 3000 μm, and preferably from 100 to 1000 μm.

In Fig. 3, wide first grooves 32 are formed between tip sections 31 and a flat surface is not formed between a side wall 35 of the first grooves 32 and side wall 35. Plural low tip sections 33 are formed between tip sections 31 and second grooves 34 are formed between low tip sections 33. In fine grooves thus formed, a maximum width of the first groove 31 is generally less tan 3000 μm, and preferably less than 1500 μm. The depth of the first groove is generally from 50 to 3000 μm, and preferably from 100 to 1000 μm. The depth of the second groove is preferably 5 to 50% of the depth of the first groove. The shape of the groove may be the shape other than that shown in Figs. 1 to 3, and a sectional width of the groove may vary along the axis direction of the groove. Furthermore, the side wall of the groove may be not linear along the axis direction of the groove, but may be curved. Such a shape must be selected so as not to prevent optical properties in the application for medical specimen.

The liquid transport film of the present invention is produced by kneading a mixture containing the polyolefin resin (A) and the polymer having a polyoxyethylene chain (B) and forming into a film using a conventional molding method such as injection molding or extrusion molding. Plural fine grooves on the liquid transport film are formed by using a mold corresponding to the shape of the groove. As the mold, a silicone mold is preferably used. When using a mold made of a material having high surface polarity such as metal, problems may occur.

On the surface opposite the surface on which grooves of liquid transport film of the present invention are formed, plural layers made of the other material for application such as substrate, or a functional layer such as adhesive layer may be formed. A cover sheet may be_^formed on the grooves so as to form a chocking channel.

EXAMPLES The present invention will now be described:

Production of liquid transport film

The following materials were kneaded and then press-molded at 200⁰C using a silicone mold to produce a film having a shape shown in Fig. 4. Materials used in each example and the size of each section are shown in Tables 1 and 2.

Materials

PPl 1 : Polypropylene (MFR = 11) manufactured by Japan Polypropylene Corporation PP45: Polypropylene (MFR = 45) manufactured by The Dow Chemical Company

PE803; Low-density polyethylene (MFR = 20) manufactured by Japan Polyethylene Corporation

P230: PELESTAT 230 manufactured by Sanyo Chemical Industries, Ltd.

P303: PELESTAT 303 manufactured by Sanyo Chemical Industries, Ltd. PEG20000: Polyethylene glycol (molecular weight: 20000) manufactured by

Wako Pure Chemicals Industries, Ltd.

106A: Nonionic surfactant manufactured by Dai-Ichi Kogyo Seiyaku Co., Ltd.

Silicone mold: SH9556RTV manufactured by Dow Corning Toray Silicone Co., Ltd.

Table 1

Kneader B: Brabender mixer, T: Twin-screw extruder Mist test:

A: Water droplets are not remained on the surface. B: Water droplets are slightly remained on the surface. C: Water droplets are considerably remained on the surface.

I to

I

Table 2

to

Evaluation of liquid transporting properties (mist test, initiaO

After vertically standing the liquid transport film thus produced, mist-like water droplets were sprayed several times. It was visually observed whether or not water droplets immediately flow downward.

Evaluation of liquid transporting propertiesCmist test, after durability test^")

After the completion of the initial test, each sample was washed with running water for 30 seconds, dried by blowing an air for one minute, and then a mist spray test was carried out again.

Evaluation of film transparency

The kneaded resin was formed into a flat film having the thickness shown in Table

2 without using a mold. Then, total light transmittance was measured by a haze meter

NDH sensor manufactured by JEOL Ltd.

Results

In case of the films of Examples 1 to 7, the polymer having a polyoxyethylene chain as a feature of the present invention is used as a hydrophilicity imparting component. As a result, mist was transported downward without being remained as droplets in initial stage and even after a durability test in the mist test. Also the total light transmittance was comparatively high. In case of Comparative Examples 1 and 2, when

P230 was used as the polymer having a polyoxyethylene chain as the hydrophilicity imparting component, sufficient transporting effect can not be obtained because of too small amount such as 10% by weight. It is considered that this amount varies depending on the material to be used as the polyolefin resin and the polymer having a polyoxyethylene chain.

In case of Comparative Examples 3 to 5, since the hydrophilicity imparting component was not added, mist was remained as water droplets in the initial stage. In case of Comparative Example 6, a surfactant is used as the hydrophilicity imparting component and mist was not converted into water droplets in the first stage, but water droplets were remained after the durability test. In case of Comparative Examples 7 to 8, a hydrophilic resin different form the polymer having a polyoxyethylene chain used in the present invention was used as the hydrophilicity imparting component and the results of the mist test were good in the initial stage and after the durability test, but the total light transmittance was comparatively low. In case of Comparative Example 9, although a film having both smooth surfaces was produced without using a mold, water droplets were remained in the first stage in the mist test. In case of Comparative Example 10, when P230 was used as the polymer having a polyoxyethylene chain as the hydrophilicity imparting component, the film was deformed by swelling because of too large amount such as 35% by weight.

Claims

What is claimed is:

1. A liquid transport film made of a mixture containing: (A) a poiyolefϊn resin, and (B) a polymer having a polyoxyethylene chain, said liquid transport film comprising plural fine grooves for controlling a flow direction of a liquid on the main surface.

2. The liquid transport film according to claim 1, wherein the mixture contains 70 to 85% by weight of the poiyolefϊn resin (A) and 30 to 15% by weight of the polymer having a polyoxyethylene chain (B).

3. The liquid transport film according to claim 1, wherein the polyolefin resin exhibits a melt flow rate (MFR) of 1 to 500.

4. The liquid transport film according to claim 1, wherein the polymer having a polyoxyethylene chain is selected from the group consisting of a polyetheresteramide, a block copolymer having a structure that a block of a polyolefin and a block of a polymer having a polyoxyethylene chain are alternately and repeatedly, bonded via at least one • bond selected from the group consisting of ester bond, amide bond, ether bond and imide bond, a polyetheramideimide, an epihalohydrin-alkylene oxide copolymer, a polyetherester, a methoxypolyethylene glycol (meth)acrylate copolymer, a polyether group-containing ethylene- vinyl acetate copolymer, and a mixture of two or more kinds of these polymers.

5. The liquid transport film according to claim 1, wherein the shape of the groove is a V-shape, a rectangular shape, or a combination of the V-shape and the rectangular shape.

6. The liquid transport film according to claim 1, wherein the depth of the groove is from 5 to 3000 μm.

7. The liquid transport film according to claim 1 , wherein the groove comprises a first groove and a second groove formed in the first groove, the depth of the first groove is from 50 to 3000 μm, and the depth of the second groove is 5 to 50% of the depth of the first groove.