JPS59185779A - Treating agent for making metallic surface hydrophilic - Google Patents

Abstract

PURPOSE:To make a metallic surface hydrophilic and to provide superior rust preventiveness by using modified polyvinyl alcohol having silyl groups in the molecule or a mixture of the polyvinyl alcohol with an inorg. substance as the titled agent. CONSTITUTION:Modified polyvinyl alcohol having silyl groups in the molecule or a mixture of the polyvinyl alcohol with an inorg. substance is used as a treating agent for making a metallic surface hydrophilic. The preferred inorg. substance contains an element having reactivity with the silyl groups in the modified polyvinyl alcohol such as Al, Si, Mg or Ca, and clay, talc or calcium carbonate is preferably used. The modified polyvinyl alcohol is blended with the inorg. substance in 0.1/99.9-100/0 ratio by pts.wt. The modified polyvinyl alcohol having silyl groups in the molecule is saponified product of a copolymer of a vinyl ester with an olefinic unsatd. monomer having a silyl group in the molecule.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hydrophilic treatment agent for metal surfaces, and more specifically, it is made of modified polyvinyl alcohol (hereinafter polyvinyl alcohol will be abbreviated as PVA) having a silyl group in the molecule, or an inorganic substance, The present invention relates to a treatment agent for making a metal surface hydrophilic, which has the ability to make a metal surface hydrophilic, suppress or prevent the generation of water droplets on the metal surface, and can provide a surface with excellent rust prevention properties.

In recent years, there has been no progress in air conditioning equipment, and in order to increase heat exchange efficiency, the heat exchange section of air conditioning equipment is designed to narrow the spacing between the fins and increase the contact area between the incoming air and the fins. However, during cooling, water droplets tend to condense on the surface of the fins, and the water droplets narrow the distance between the fins, significantly increasing ventilation resistance and reducing heat exchange efficiency.

Conventionally, in order to improve these problems, a method has been proposed in which the metal surface is coated with a hydrophilic polymer such as PVA and silica, or a combination of these and a low-molecular organosilicon compound (Japanese Patent Application Laid-Open No. 55-99976J). However, coatings made by this method have a drawback in that they have low adhesion to metals when exposed to water and cannot withstand long-term use.

As a result of intensive research aimed at overcoming the above-mentioned drawbacks, the inventors of the present invention found that when a metal surface is coated with modified PVA having a silyl group in the molecule or a treatment agent consisting of this and an inorganic substance,
It improves the water fragility of the metal surface, suppresses or prevents the formation of water droplets on the metal surface, has high adhesion to the metal even when wet, and also improves the rust resistance of the metal surface. I have now completed the present invention.

The present invention will be explained in more detail below.

The modified PVA containing silicon in the molecule used in the present invention may be one containing silicon in the molecule, but
Particularly preferred are those in which the silicon contained in the molecule has a reactive substituent such as an alkoxyl group, an acyloxyl group, a silanol group which is a hydrolyzate of Kowara, or a salt thereof.

Methods for producing such modified PVA include: (1) introducing silicon into PVA or modified polyvinyl acetate containing a carboxyl group or a hydroxyl group by post-modification using a silylating agent; (2) Intra-molecular bonding with vinyl ester? ζMethod for saponifying a copolymer of a laryl group and an olefinically unsaturated monomer contained therein or a copolymer of an olefinically unsaturated monomer having an ionic hydrophilic group in the molecule, ■Mercaptan having a silyl group A polymer or copolymer with a silyl group at the end obtained by copolymerizing a vinyl ester with an olefinic unsaturated monomer having an ionic hydrophilic group in the molecule. Examples include a method of saponifying a polymer. In the method of post-modifying PVA or modified polyvinyl acetate using a silylating agent, for example, silylation is carried out in an organic solvent that does not react with the silylating agent, such as benzene, toluene, xylene, hexane, heptane, ether, or atom. The powdered PVA or the above modified polyvinyl acetate is suspended in the solution with stirring, and the silylating agent and PVA or the above modified polyvinyl acetate are mixed at a temperature ranging from room temperature to the boiling point of the silylating agent. Silyl group-containing modified PVA 1 can be obtained by the reaction or by further saponifying the vinyl acetate unit using an alkali catalyst or the like. Examples of silylating agents used in post-modification include organohalogensilanes such as trimethylchlorosilane, dimethyldichlorosilane, methyltrichlorosilane, vinyltrichlorosilane, diphenyldichlorosilane, and triethylfluorosilane, trimethylacetoxysilane, and dimethyldiacetoxysilane. organosilicon esters such as silanes,
Organoalkoxysilanes such as trimethylmethoxysilane and dimethyldimethoxysilane; organosilanols such as trimethylsilanol and diethylsilanediol;
Examples include aminoalkylsilanes such as N-aminoethylaminopropyltrimethoxysilane, organosilicon isocyanates such as trimethylsilicon isocyanate, and the like. The introduction rate of the silylating agent, that is, the degree of modification, can be arbitrarily adjusted depending on the amount of the silylating agent used and the reaction time.

The degree of polymerization and saponification of the resulting silyl group-containing modified PVA can be arbitrarily adjusted by adjusting the degree of polymerization and saponification of the PVA used or the degree of polymerization and saponification of the modified polyvinyl acetate.

In addition, in a method of saponifying a copolymer of a vinyl ester and an olefinically unsaturated monomer containing a silyl group in the molecule, or a copolymer of a vinyl ester and an olefinically unsaturated monomer having an ionic hydrophilic group in the molecule. For example, in an alcohol, a vinyl ester and an olefinically unsaturated monomer containing a silyl group in the molecule, or a vinyl ester and an olefinically unsaturated monomer having an ionic hydrophilic group in the molecule are radical-initiated. The process involves copolymerizing the copolymer using a silyl group-containing modified PV, A, or silyl group, and then saponifying the copolymer by adding an alkali or acid catalyst to the alcohol solution of the copolymer. Modified PVA having a hydrophilic group can be obtained. Examples of the silyl group-containing olefinically unsaturated monomer used in this method include vinylsilanes represented by the following formula (I) and (meth)acrylamide-alkylsilanes represented by (■).

B'm ■ 0H4=OR-(OH2)n-8i -(E2)5-m
(1) f('E' m II an5=cn5-aN-B5-si-12)3-m
1 for f [where n is 0 to 4, m is 0 to 2, B1 is carbon number 1 to 5
an alkyl group (methinopethyl, etc.), J32 is an alkoxyl group or acyloxyl group having 1 to 40 carbon atoms (here, the alkoxyl group or acyloxyl group may have an oxygen-containing substituent; 8B5 is a hydrogen atom or methyl group, B4 is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and BS is an alkylene group having 1 to 5 carbon atoms or a divalent organic residue in which chain carbon atoms are bonded to each other by oxygen or nitrogen. 1 is 2 in the same monomer
If there are 11, 11 may be the same,
They may be different. Also, when two or more R2s exist in the same monomer, 1 (2 may be the same or different) Examples include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris-(β-methoxyethoxy)silane, vinyltriacetoxysilane, allyltrimethoxysilane, allyltriacetoxysilane, vinylmethyldimethoxysilane,
Vinyldimethylmethoxysilane, vinylmethyljethoxysilane, vinyldimethylethoxysilane, vinylmethyldiacetoxysilane, vinyldimethylacetoxysilane, vinylisobutyldimethoxysilane, vinyltriisopropoxysilane, vinyltributoxysilane, vinyltrihexyloxysilane, vinyl Methoxydihexyloxysilane, vinyldimethoxyoctyloxysilane,
Vinylditoxyoctyloxysilane, vinyltrioctyloxysilane, vinylmethoxydioleyloxysilane,
Vinyldimethoxyoctyloxysilane, vinylmethoxydioleyloxysilane, vinyldimethoxyoctyloxysilane, and also the general formula (% formula %) (where B1 and m are the same as above, and X represents 1 to 20)
Examples include polyethylene glycol represented by the following and nylsilane. Further, specific examples of the (meth)acrylamido-alkylsilane not represented by formula (II) include 3-(meth)acrylamidopropyltrimethoxysilane, 6-(meth)acrylamidopropyltriethoxysilane, 3-(meth)acrylamidopropyltriethoxysilane, ) acrylamide-propyltri(β-methoxyethoxy)silane, 2-(meth)acrylamido-2-methylpropyltrimethoxysilane, 2-(meth)acrylamido-2-methylethyltrimethoxysilane, N-(2-( meth)acrylamide
ethyl)-aminopropyltrimethoxysilane, 3-(
meth)acrylamide-propyltriacetoxysilane, 2-(meth)acrylamide-ethyltrimethoxysilane, 1-(meth)acrylamide-methyltrimethoxysilane, 6-(meth)acrylamide-propylmethyldimethoxysilane, 6-(meth)acrylamide-propylmethyldimethoxysilane Acrylamide-propyldimethylmethoxysilane, 3-(N-methyl-(
meth)acrylamido)-propyltrimethoxysilane, 5-CC meth)acrylamido-methoxy)-3-hydroxypropyltrimethoxysilane, 6-((metalacrylamide methoxy)-propyltrimethoxysilane, dimethyl-6-(meth) Acrylamide-propyl-5-(trimethylsilyl)propylammonium chloride, dimethyl-2-(meth)acrylamide =
-2-methylpropyl-6-(trimethoxysilyl)propylammonium chloride and the like.

In addition, the olefinically unsaturated monomers having an ionic hydrophilic group in the molecule that may be used in this method include olefinically unsaturated monomers having a carboxyl group, a sulfonic acid group and a stiff salt, or an amino group or an ammonium base. Examples include saturated monomers, but the present invention also includes olefinic unsaturated monomers having esters, amides, or imides of the above-mentioned ionic hydrophilic groups that generate ionic hydrophilic groups when saponifying the copolymer. It is included in the olefinically unsaturated monomer having an ionic hydrophilic group used. Specifically, (meth)acrylic acid, maleic anhydride, itaconic acid,
Sowara salts or Sowara monomers include dialkyl esters, (meth)acrylamide, vinylsulfonic acid, allylsulfonic acid, 3-(meth)acrylamide-propylsulfonic acid, 2-(meth)acrylamide-2-methylpropylsulfonic acid, and the like. salts or alkyl esters thereof, vinylamines, vinylsuccinimides,
Vinylamine derivatives such as methyl-N-vinyl carbamate and methyl-N-vinyl carbamate, N-vinylimidazole, 2-methyl-N-vinylimidazole, N
, N-dimethyl-6-(meth)acrylamide-propylamine, N,N-dimethyl-2-(meth)acrylamide-2-methylpropylamine, primary to quaternary ammonium salt derivatives of Kowara, etc. can be used. When modified PVA into which stiff ionic hydrophilic groups have been introduced is used, the water-absorbability of the metal surface becomes even better. Alternatively, a vinyl ester is polymerized in the presence of a mercaptan having a silyl group, or
Alternatively, in a method of saponifying a polyvinyl ester or copolymer having a silyl group at the end, which is not obtained by copolymerizing a vinyl ester and an olefinically unsaturated monomer having an ionic hydrophilic group in the molecule, For example, when a vinyl ester or a vinyl ester and an olefinic unsaturated monomer having an ionic hydrophilic group in the molecule are polymerized using a radical initiator, a mercaptan having a silyl group is added to the polymerization system all at once, in parts, or continuously. The polyvinyl ester or copolymer having a silyl group at the end is produced by adding pucaptan having a silyl group to the polymerization system, and by chain transfer to the mercaptan. By saponifying the polyvinyl ester by adding an alkali/lubricant or acid catalyst to an alcohol solution, a modified PVA having a silyl group can be obtained. 3-(trimethoxysilyl)-propyl mercaptan, 6-(triethoxysilyl)-propyl mercaptan, etc. are used. Examples of the vinyl ester used in the method (1) or (2) above include vinyl acetate, vinyl propionate, vinyl formate, etc., but vinyl acetate is preferred from an economic standpoint.

Among the above-mentioned six production methods of modified PVA containing a silyl group in the molecule used in the present invention, methods
'It is preferably used in terms of VA homogeneity.

Modified PV containing silyl group used in the present invention
The content of the silyl group or ionic hydrophilic group in A, the degree of saponification, or the degree of polymerization are appropriately selected depending on the purpose.
There are no restrictions. The silyl group is effective even at a relatively small content.
01-1-0 mol%, preferably 0.1-2.5 mol%
The content of ionic hydrophilic groups is usually 0.2 to 10 mol%, preferably 0.5 to 5 mol%.
Choose from the range. The saponification degree is usually preferably in the range of 70 to 100 mol%. In addition, the degree of polymerization is usually 10 to 30 0
Select from the range.

To dissolve the above-mentioned modified PVA used in the present invention in water, the modified PVA is usually dispersed in water (if necessary, an alkali such as sodium hydroxide is added and stirred). By heating at the same time, uniform water solubility can be obtained.

The inorganic substance optionally used in the present invention is preferably one containing an element having sosilyl group reactivity in modified PVA such as aluminum, silicon, magnesium, calcium, etc. Specifically, tζ is clay, talc, calcium carbonate, Examples include aluminum silicate, calcium silicate, silica, sand, aluminum oxide, and the like. Furthermore, water-soluble silicates such as hydrolath, water-soluble aluminum compounds such as aluminum sulfate and sodium aluminate, and water-soluble zirconium compounds such as ammonium zirconium carbonate can also be used, but modified polyvinyl containing silyl groups in the molecule can also be used. This is not the best method because it tends to increase the viscosity of the alcohol aqueous solution. By using a stiff inorganic substance, the rust prevention properties of the metal surface can be further improved, as is clear from the examples described below. For the purpose of the present invention, water-insoluble inorganic particles are preferred, and colloidal silica, finely divided silica particles, etc. are particularly preferred in view of the water stiffness and water resistance of the resulting coating film.

When used by blending an inorganic substance with modified PVA having a silyl group in the molecule, the blending ratio is former/latter 0.1/99.
9 to 10010 (parts by weight), preferably 1/99 to
It is preferable to adjust it so that it becomes 9515. If the latter compounding ratio exceeds 99.9, the adhesion to the metal surface will be insufficient.

The hydrophilic treatment agent for metal surfaces of the present invention must contain modified PVA or stiffness having the same molecular number ζ silyl group, and an inorganic substance. It is also possible to contain inhibitor additives, other water-soluble polymers, aqueous polymer dispersions, and the like. Water is preferably used as a solvent, but various alcohols, ketones,
Solvents such as dimethylformamide and dimethyl sulfoxide can be used in combination, and additives include various antifoaming agents, various dispersants, nonionic or anionic surfactants, silane coupling agents, and PH regulators. Furthermore, pigments with optical hiding properties (such as titanium oxide), or rust inhibitors (such as chromate-based compounds, lead-based compounds, molybdate-based compounds, tannic acid-based or gallic acid-based compounds, organic or Examples of water-soluble resins include cellulose derivatives such as carboxymethyl cellulose and hydroxyethyl cellulose, poly(meth)acrylic acid, polyhydroxy(meth)acrylate or its copolymer, polyacrylamide, etc. (meth)acrylic polymer, polyvinylpyrrolidone length or its covalent carboxy group-containing PVA,
Sulfate group-containing modified PVA, sulfonic acid group-containing modified PVA,
Examples include modified PVA containing an IJ acid group, modified PVA containing a quaternary ammonium base, modified PVA containing an amino group, and PVA derivatives such as general PVA. Furthermore, as polymer aqueous dispersions, acrylic polymers and copolymers, ethylene-
Examples include aqueous dispersions such as vinyl acetate copolymers, vinyl ester spinning wheel polymers and copolymers, and styrene-butadiene copolymers.

The processing agent of the present invention is dissolved or dispersed in water or water containing the above-mentioned organic solvent, and used as an aqueous solution or an aqueous dispersion.

As a method for applying the treatment agent of the present invention to a metal surface, it is possible to use various methods commonly known in the art, such as brush coating, dip coating, and spray coating. After the treatment agent of the present invention is applied by the above-mentioned method, acid treatment,
By appropriately performing heat treatment, it is possible to obtain a hydrophilic film that has a high adhesive strength to the surface of the metal grinder.

The coating film obtained by the hydrophilic treatment agent of the present invention is sufficiently practical as a foam itself, but in order to make the effect even more remarkable, the coating film formed has a hydrophilic property of Meishin. Post-treatments such as applying and impregnating substances, surfactants, etc. are also effective in improving the water resistance of the coating film surface.

Examples of the metal to be coated include aluminum, aluminum alloy, copper, brass, galvanized steel sheet, iron, etc., but aluminum, aluminum alloy, etc. used for fins of V-type equipment are particularly preferably used. do.

The hydrophilic treatment agent of the present invention is characterized in that it has excellent water adhesion properties, significantly suppresses the formation of water droplets on metal surfaces, has high adhesive strength to metals, and also has excellent rust prevention properties for metals. It is. Although the reason why the treatment agent of the present invention has the above-mentioned remarkable performance is not yet fully elucidated, the hydroxyl group and ionic hydrophilic In addition, inorganic substances, especially silica-based inorganic substances, etc., exhibit water-resilient properties, and silyl groups with alkoxyl groups or acyloxyl groups bonded to them, or silanol groups, which are hydrolyzed products of stiffness, or salts thereof. is inorganic, metal and modified PV
The stiff particles react with each other and form a strong film that strongly adheres to the metal surface, inhibiting the immersion of water into this film. It is presumed that the adhesion to metal will be increased even when wet, and the rust-preventing effect will also be exhibited.

Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these examples.

In the examples, parts or % indicate parts by weight or weight*% unless otherwise specified.

Example 1 Silyl groups obtained by saponifying a copolymer of vinyltrimethoxysilane and vinyl acetate are used as vinylsilane units, the content is 4 mol%, and the degree of saponification of vinyl acetate units is 98.
37.5 parts of colloidal silica dispersion (Nissan Chemical Industries, Ltd., Snowtex-20, solid content 20%) was added to 100 parts of a 5% aqueous solution of modified FVA having a silyl group in the molecule with a polymerization degree of 550 and a polymerization degree of 550. and water were added to prepare an aqueous dispersion having a solid content of 5%. This dispersion was then spread to a thickness of 0.17
It was applied to a 1i aluminum thin plate to a dry thickness of 5 microns, and then dried at 150°C for 5 minutes.

The water resistance, adhesive strength, and corrosion resistance of the resulting coating film Cζ were measured. The results are shown in Table 1. Table 1: It can be seen that the treatment agent of the present invention is excellent in wet resistance, adhesive strength when wet, and rust prevention.

Examples 2 to 4 The same procedure as in Example 1 was carried out except that the following treatment agents were used in place of the treatment agents used in Example 1.

The results are also shown in the table.

Treatment agent used in Example 2: 0.5 mol% of sealyl group obtained by saponifying a copolymer of vinyltrimethoxysilane, hinyl acetate, and sodium 2-acrylamide-2-methylpropylsulfonate, and sulfone. 10 parts of modified PVA containing 1 mol% of acid groups, a degree of saponification of vinyl acetate units of 99.0 mol%, a blood content of 11600, and a particle size of 0.1
A 10% solids aqueous dispersion containing 5 parts of ~1 micron silica particulates.

Treatment agent used in Example 3: Contains 1.0 mol% of silyl groups and 2.0 mol% of maleic acid groups obtained by saponifying a copolymer of vinyltrimethoxysilane, vinyl acetate, and dimethyl maleate. and the degree of saponification of vinyl acetate unit is 9
7.9 mol%, modified FVA with a degree of polymerization of 500 and Snowtex at a solid content ratio of 2/1 (with a solid content of 5
% aqueous dispersion.

Treatment agent used in Example 4: Contains 0.7 mol% of silyl groups obtained by saponifying a comonomer of vinyltriisopropoxysilane and vinyl acetate, and has a degree of saponification of vinyl acetate units of 90.1 Mol%, 1 of modified PVA with a degree of polymerization of 1300
0% water drilling fluid.

Comparative Example 1 General partially saponified PVA was used instead of the modified PVA of Example 1.
(saponification degree 88 mol%, total 1550), 50 parts colloidal silica (Nissho Kagaku Kogyo ■, Snowtex-0, solid content 2%) and vinyl tris (
The procedure of Example 1 was repeated except that a composition was prepared by adding 2 parts of (β-methoxyethoxy)silane and water to make the solid content 10%, and then heating the mixture at 80° C. for 1 hour. The results are also shown in Table 1.

Comparative Example 2 The aluminum thin plate used in Example 1 was used to measure its corrosion resistance. The results are shown in Table 1.

1) When the surface opposite to the coated surface is cooled to 20℃ in a constant temperature and humidity room at 30℃ and 190% EH, judge whether or not water droplets are generated on the coated surface. ◎: No water droplets generated, ○:
A few water droplets are observed. ×: A large amount of water droplets are generated.2) Use a knife to make cuts perpendicular to the 11 vertical and horizontal group intervals in a grid pattern on one side until it reaches the aluminum plate. After making 100 squares with a length of 1, leave it as it is (normal)
Alternatively, after immersing in water at 20° C. for 12 hours and wiping off the water on the surface, a cellophane adhesive tape was applied to the surface and instantly peeled off, and the number of squares that remained intact was expressed as the number of squares.

3) According to JIS-Z-2371m water jet M test M method +<　.

Patent applicant: Kuraray Co., Ltd. Representative Patent Attorney Ken Honda

Claims (9)

[Claims] (1) A metal surface hydrophilic treatment agent consisting of modified polyvinyl alcohol having a silyl group in the molecule or an inorganic substance. (2) The modified polyvinyl alcohol having a silyl group in the molecule is a saponified product of a copolymer of a vinyl ester and an olefinically unsaturated monomer having a silyl group in the molecule. Hydrophilic treatment agent for metal surfaces. (3) The agent for making a metal surface hydrophilic according to claim 2, wherein the olefinically unsaturated monomk compound having a silyl group in the molecule is vinylalkoxysilane. (4) The agent for making a metal surface hydrophilic according to claim 2, wherein the olefinically unsaturated monomer having a silyl group in the molecule is (meth)acrylamide-alkylalkoxysilane. (5) Claim 1, wherein the modified polyvinyl alcohol having a silyl group in the molecule is a saponified product of a polyvinyl ester having a silyl group at the end obtained by polymerizing a vinyl ester in the presence of a mercaptan having a silyl group.
A hydrophilic treatment agent for a metal surface as described in . (6) Modified polyvinyl alcohol having a silyl group in the molecule contains a vinyl ester, an olefinically unsaturated monomer having a silyl group in the molecule, and an olefinically unsaturated monomer having an ionic hydrophilic group in the molecule. The agent for making a metal surface hydrophilic according to claim 1, which is a saponified product of a copolymer. (7) The olefinically unsaturated monomer having an ionic hydrophilic group in the molecule is one selected from the group consisting of a carboxyl group, a sulfonic acid group, a salt thereof, an ester group thereof, an amino group and an ammonium base, or The agent for making a metal surface hydrophilic according to claim 6, which is an olefinically unsaturated monomer having two or more types of ionic hydrophilic groups. (8) Modified polyvinyl alcohol having a silyl group in the molecule is obtained by copolymerizing a vinyl ester and an olefinically unsaturated monomer having an ionic hydrophilic group in the molecule in the presence of a mercaptan having a silyl group. The agent for making a metal surface hydrophilic according to claim 1, which is a saponified product of a copolymer having a silyl group at the end thereof. (9) The agent for making a metal surface hydrophilic according to claim 1, wherein the inorganic substance is colloidal silica.