JP4136472B2 - Polyisocyanate for water-based coating agent and method for surface treatment of porous substrate using the same - Google Patents

Description

【００７３】
浸透性については、図１〜図８から明らかなように、比較例１〜２では、基材表面に薄く均一に塗膜が残存しており、比較例３〜４では、部分的又は全体的に濃く光沢のある樹脂状皮膜が形成されていた。なお、実施例及び参考例では、写真において、下地である珪酸カルシウム板の濃淡が現れており、塗布部と未塗布部とで実質的な差異が見られなかった。
【図面の簡単な説明】
【図１】 図１は実施例１でのシーラーの浸透性の結果を示す写真である。
【図２】 図２は参考例１でのシーラーの浸透性の結果を示す写真である。
【図３】 図３は実施例２でのシーラーの浸透性の結果を示す写真である。
【図４】 図４は参考例２でのシーラーの浸透性の結果を示す写真である。
【図５】 図５は比較例１でのシーラーの浸透性の結果を示す写真である。
【図６】 図６は比較例２でのシーラーの浸透性の結果を示す写真である。
【図７】 図７は比較例３でのシーラーの浸透性の結果を示す写真である。
【図８】 図８は比較例４でのシーラーの浸透性の結果を示す写真である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a self-emulsifiable allophanate group-containing polyisocyanate useful as various industrial materials such as a sealer composition for a porous substrate, and a method for preparing a substrate for a porous substrate. More specifically, the present invention relates to a self-emulsifiable allophanate group-containing polyisocyanate having substantially free volatile organic solvent and having a stable free isocyanate group even when emulsified in water.
[0002]
[Prior art]
In general, in porous inorganic base materials such as calcium silicate board, plaster board, lightweight cellular concrete (ALC) board, rock wool board, etc., the surface layer strength of the base material is increased, or it is used with cosmetic paint or resin impregnated paper as a finishing treatment. In order to improve the adhesion and water stop performance, a base treatment with a sealer is performed. Conventionally, solvent-based sealers such as urethane resin-based, epoxy resin-based, and vinyl chloride resin-based are mainly used in such a base treatment, and a moisture-curable urethane resin-based sealer is known as a typical one. ing. This moisture curable urethane resin-based sealer is good in terms of surface layer reinforcing effect, water-stopping performance, and adhesion to a finishing agent in the initial stage. However, when left for a long period of time with the sealer treatment, the curing of the coating film proceeds to a high degree, and the adhesion to the finishing agent decreases. Moreover, since the sealer is based on an organic solvent, it has a safety and health problem. Furthermore, since the solvent used as the diluent is expensive and is usually a mixed solvent, the cost becomes high even if recovery and reuse are taken into consideration.
[0003]
On the other hand, as a method using an aqueous sealer, for example, Japanese Patent No. 3201660 discloses a method of diluting an emulsifiable hydrophilic group-containing isocyanate prepolymer with water and using it in a base treatment. Although this method has an advantage that no organic solvent is used, since the isocyanate reacts with water immediately after mixing with water, the pot life is shortened and the working efficiency is lowered. Moreover, since the permeability to the porous inorganic base material is low, a coating film is formed on the surface of the base material, and not only the strength of the surface layer of the base material can be improved but also the adhesion to the finishing material is lowered.
[0004]
JP-A-11-29741 discloses a hydrophilic isocyanate group-terminated compound obtained by reacting an organic polyisocyanate which may be modified with carbodiimide, biuret or isocyanurate and an alkoxy (polyoxyalkylene) glycol. A self-emulsifying primer for resinous pavement containing benzene is disclosed. This document discloses an isocyanate group-terminated prepolymer having a viscosity of 300 mPa · s / 25 ° C. obtained from polymeric MDI (polymethylene polyphenylene polyisocyanate) and methoxypolyethylene glycol having a number average molecular weight of 400. However, this document does not disclose polyisocyanates having allophanate groups.
[0005]
JP-A-11-310700 discloses a modified polyisocyanate composed of a reaction product of a polyisocyanate and a nonionic emulsifier having an HLB of 17 or less and containing an average of 15 to 35 ethylene oxide units in one molecule. It is described that this modified polyisocyanate is useful as a curing agent or a crosslinking agent for an aqueous resin composition. This document describes a viscosity of 400 mPa · s (23 ° C.) obtained from an allophanate group and isocyanurate group-containing polyisocyanate based on HDI (hexamethylene diisocyanate) and polyethylene nonylphenyl ether having an oxyethylene chain unit of 20. ) Polyisocyanates. However, this document does not describe the use of polyisocyanate to treat a porous substrate such as concrete as a base.
[0006]
[Problems to be solved by the invention]
Accordingly, an object of the present invention is to provide a polyisocyanate for an aqueous coating agent that has high permeability to a porous substrate and is suitable for treatment, and a method for ground treatment of a porous substrate using the same. is there.
[0007]
Another object of the present invention is to use a polyisocyanate for an aqueous coating solution that is useful for improving the strength and water-stopping performance of the surface layer of a porous substrate without impairing the adhesion to the finishing agent. An object of the present invention is to provide a method for ground treatment of a porous substrate.
[0008]
Still another object of the present invention is to provide a polyisocyanate for an aqueous coating agent that can improve pot life even when used as an aqueous treatment agent or an aqueous composition.
[0009]
[Means for Solving the Problems]
As a result of intensive studies to solve the above problems, the present inventors have found that when an aqueous sealer (or an aqueous composition) having an allophanate group and containing a low-viscosity self-emulsifiable polyisocyanate is used, the porous structure is porous. It has been found that the permeability to the base material can be improved, the adhesion to the finishing agent, the strength of the surface layer of the base material and the water stopping performance can be improved, and further the pot life of the aqueous composition can be extended, and the working efficiency can be improved. The present invention has been completed.
[0010]
  That is, the polyisocyanate for an aqueous coating agent of the present invention is an emulsifiable polyisocyanate having an allophanate group,Allophanate group-containing polyisocyanate and polyoxyethylene C having 5 to 12 oxyethylene units _1-6 Obtained by reaction with an alkyl ether,The viscosity of the solid content at 25 ° C.50 to 550 mPa · sIt is. The polyisocyanate may contain a polyoxyethylene chain at a ratio of about 1 to 15% by weight. Moreover, the allophanate group and the isocyanurate group may be included at a ratio of the former / the latter (molar ratio) = 100/0 to 20/80. The emulsifiable polyisocyanate is a polyisocyanate for treating a porous substrate by diluting with water.TheThe reoxyethylene chain may be contained at a ratio of 1 to 10% by weight.
[0011]
The present invention also includes a method for ground treatment of a porous substrate in which an aqueous coating agent containing the emulsifiable polyisocyanate and water is applied to the porous substrate. The aqueous coating agent may contain polyisocyanate and water at a ratio of the former / the latter (weight ratio) = 10/90 to 90/10. The porous substrate may be composed of at least a hydraulic inorganic component (cement, gypsum, silicate, etc.).
[0012]
The present invention further includes a method for improving the permeability or impregnation property with respect to the porous substrate using the aqueous treatment agent containing the emulsifiable polyisocyanate.
[0013]
In the present specification, the term “self-emulsifying” means mixing with water to form a uniform dispersion or a transparent aqueous composition.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
[Polyisocyanate]
The polyisocyanate for an aqueous coating solution of the present invention is an emulsifying (self-emulsifying) polyisocyanate having an allophanate group, and has a low solid content viscosity at 25 ° C. of 1000 mPa · s or less.
[0015]
Such a polyisocyanate can be obtained by reacting an allophanate group-containing polyisocyanate with a hydrophilic compound having an active hydrogen atom capable of reacting with the polyisocyanate and capable of imparting self-emulsifying properties. Has an isocyanate group.
[0016]
(Allophanate group-containing polyisocyanate)
The allophanate group-containing polyisocyanate is obtained by adding a polyisocyanate compound in a conventional manner, for example, in such a manner that the ratio of isocyanate groups to hydroxyl groups is excessive in the presence or absence of a catalyst such as a tertiary amine or a metal compound. It can be obtained by a method of making it allophanate by reacting with (such as ethylene glycol). The polyisocyanate having an isocyanurate group together with an allophanate group is a polyisocyanate having an allophanate group by allophanating a polyisocyanate obtained by reacting a monoalcohol with an excess polyisocyanate compound. Can be obtained by a method of mixing with a polyisocyanate having an isocyanurate group obtained by isocyanurate, or a method of subjecting the polyisocyanate to allophanate and isocyanurate. Details of the method for producing such a polyisocyanate are described in, for example, British Patent No. 994890, U.S. Pat. Nos. 4,177,342, 4,160080, 3,769,318 and 4,810,820, Japanese Patent Publication No. 46-1711, Reference can be made to Japanese Patent Publication No. 49-40860 and Japanese Patent No. 3244297.
[0017]
As the base polyisocyanate compound, aliphatic polyisocyanate, alicyclic polyisocyanate, or derivatives thereof can be used from the viewpoint of coating properties of the emulsion.
[0018]
Examples of the aliphatic polyisocyanate include diisocyanate [trimethylene diisocyanate, tetramethylene diisocyanate, 1,6-diisocyanatohexane (hexamethylene diisocyanate, HDI), pentamethylene diisocyanate, 1,2-propylene diisocyanate, 1,2- Butylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, 2,4,4- or 2,2,4-trimethylhexamethylene diisocyanate, 2,6-diisocyanate methyl captroate etc.], polyisocyanate [ Lysine ester triisocyanate, 1,4,8-triisocyanate octane, 1,6,11-triisocyanate undecane, 1,8-diisocyanate-4-isocyanate DOO methyl octane, 1,3,6-triisocyanate hexane, 2,5,7-trimethyl-1,8-diisocyanate-5-isocyanatomethyl octane] can be exemplified.
[0019]
Examples of the alicyclic polyisocyanate include diisocyanate [1,3-cyclopentane diisocyanate, 1,3-cyclopentene diisocyanate, 1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, 1-isocyanato-3,3,5. -Trimethyl-5-isocyanatomethyl-cyclohexane (isophorodiisocyanate, IPDI), 4,4'-, 2,4'- or 2,2'-methylenebis (cyclohexyl isocyanate) or mixtures thereof (hydrogenated MDI), methyl -2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, 1,3- or 1,4-bis (isocyanatomethyl) cyclohexane or a mixture thereof (hydrogenated XDI), etc.], polyisocyanate [1 3,5-triisocyanatecyclohexane, 1,3,5-trimethylisocyanatecyclohexane, 2- (3-isocyanatopropyl) -2,5-di (isocyanatemethyl) -bicyclo (2.2.1) heptane, 2- ( 3-isocyanatopropyl) -2,6-di (isocyanatomethyl) -bicyclo (2.2.1) heptane, 3- (3-isocyanatopropyl) -2,5-di (isocyanatomethyl) -bicyclo (2.2 .1) Heptane, 5- (2-isocyanatoethyl) -2-isocyanatomethyl-3- (3-isocyanatopropyl) -bicyclo (2.2.1) heptane, 6- (2-isocyanatoethyl) -2-isocyanate Methyl-3- (3-isocyanatopropyl) -bicyclo (2.2.1) heptane, 5 (2-isocyanatoethyl) -2-isocyanatomethyl-2- (3-isocyanatopropyl) -bicyclo (2.2.1) -heptane, 6- (2-isocyanatoethyl) -2-isocyanatomethyl-2- (3 -Isocyanatopropyl) -bicyclo (2.2.1) heptane etc.].
[0020]
Examples of the derivative from polyisocyanate include multimers of the above polyisocyanates [dimers, trimers (isocyanurate group-containing polyisocyanates), pentamers, heptamers, etc.], biuret group-containing polyisocyanates (for example, , Biuret-modified polyisocyanate produced by the reaction of the polyisocyanate and water), urethane group-containing polyisocyanate (for example, urethane obtained by modifying or reacting part of the isocyanate group in the polyisocyanate or multimer with monool or polyol) Modified polyisocyanates, etc.), urea group-containing polyisocyanates (for example, urea-modified polyisocyanates produced by reaction of the polyisocyanates with diamines), oxadiazinetrione group-containing polyisocyanates (for example, Such oxadiazinetrione-modified polyisocyanates produced by reaction of the such polyisocyanate with carbon dioxide) and the like. Of these, HDI-based derivatives and isocyanurate group-containing polyisocyanates (particularly diisocyanates) are preferred. In the polyisocyanate derivative, the isocyanate group content can be appropriately selected and is usually about 12 to 40% by weight, preferably about 15 to 35% by weight, based on the total polyisocyanate used.
[0021]
These polyisocyanates can be used alone or in combination of two or more. For example, a polyisocyanate derivative and an aliphatic and / or alicyclic polyisocyanate may be used in combination.
[0022]
Of these polyisocyanates, diisocyanates, especially aliphatic diisocyanates such as HDI (C_4-10Alkylene diisocyanate and the like) or derivatives thereof (isocyanurate group-containing polyisocyanate which is a trimer of HDI) are preferable.
[0023]
It should be noted that allophanate groups in the emulsifying polyisocyanate seem to reduce the viscosity of the emulsifying polyisocyanate.
[0024]
In the allophanate group-containing polyisocyanate, the ratio of the allophanate group to the isocyanurate group is the former / the latter (molar ratio) = 100/0 to 20/80, preferably 100/0 to 30/70, more preferably 90/10. About 50/50. The ratio may be 4/1 to 1/10, preferably 4/1 to 1/3, more preferably 3/1 to 1/2, particularly about 2/1 to 1/2.
[0025]
In addition, aromatic polyisocyanate [m- or p-phenylene diisocyanate, 2,4- or 2,6-tolylene diisocyanate (TDI), 4,4'-, if necessary, as long as the characteristics of the present invention are not impaired. 2,4'- or 2,2'-diphenylmethane diisocyanate (MDI), 4,4'-toluidine diisocyanate (TODI), 4,4'-diphenyl ether diisocyanate, 4,4'-diphenyl diisocyanate, 1,5-naphthalene diisocyanate (NDI), or mixtures thereof], araliphatic polyisocyanates [1,3- or 1,4-xylylene diisocyanate (XDI), 1,3- or 1,4-tetramethylxylylene diisocyanate (TMXDI), ω, ω'-diisocyanate-1,4-diethylbenzene Or a mixture thereof] may be used in combination.
[0026]
(Hydrophilic compound)
The hydrophilic compound has an active hydrogen atom capable of reacting with an isocyanate group of the allophanate group-containing polyisocyanate and a hydrophilic site capable of self-emulsification. Examples of the reactive group having an active hydrogen atom capable of reacting with an isocyanate group include a hydroxyl group and a mercapto group, and a hydroxyl group is particularly preferable. In addition, the hydrophilic portion is usually composed of a polyoxyalkylene chain, and is preferably composed of at least a polyoxyethylene chain from the viewpoint of self-emulsification. As such a compound, a polyoxyalkylene compound having at least an oxyethylene unit, particularly a polyoxyethylene compound having a hydroxyl group is usually used. The hydrophilic compounds can be used alone or in combination of two or more.
[0027]
In the polyoxyalkylene compound, examples of the oxyalkylene unit include oxyC such as oxyethylene, oxypropylene, oxytrimethylene, and oxybutylene._2-5Alkylene units (especially oxy-C_2-3Alkylene unit). These oxyalkylene units only need to contain at least an oxyethylene unit._3-4It may be a random or block copolymerized unit with an alkylene unit. The content of oxyethylene units in the polyoxyalkylene units is usually about 70 to 100 mol%, preferably about 80 to 100 mol%. In order to provide the allophanate group-containing emulsifiable polyisocyanate with a good balance between emulsifiability and practical pot life (pot life), the polyoxyalkylene compound has 5 to 17 oxyethylene units, preferably 5 to 15 It is preferable to have about 7 to 12 pieces (for example, 6 to 14 pieces), more preferably about 7 to 12 pieces.
[0028]
The compound having a polyoxyalkylene chain (particularly polyoxyethylene chain) includes a compound having at least one active hydrogen atom (particularly a hydroxyl group) at the terminal. Examples of such compounds include polyoxyethylene monoalkyl ethers (for example, polyoxyethylene C such as polyoxyethylene monomethyl ether, polyoxyethylene monoethyl ether, polyoxyethylene monopropyl ether, polyoxyethylene monobutyl ether)._1-24Alkyl ethers, preferably polyoxyethylene C_1-10Alkyl ether), polyoxyethylene monoalkyl aryl ether (for example, polyoxyethylene C such as polyoxyethylene monooctyl phenyl ether, polyoxyethylene monononyl phenyl ether, polyoxyethylene monodecyl phenyl ether)_8-12Alkyl-C_6-12Aryl ethers), polyoxyethylene sorbitan higher fatty acid esters (polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan distearate, polyoxyethylene sorbitan tristearate Polyoxyethylene sorbitan such as rate-mono, di or tri C_10-24Fatty acid esters), polyoxyethylene mono-higher fatty acid esters (polyoxyethylene mono-C such as polyoxyethylene monolaurate, polyoxyethylene monostearate)_10-24Fatty acid esters and the like). These compounds having a polyoxyethylene chain can be used alone or in combination of two or more.
[0029]
Preferred polyoxyethylene chain-containing compounds include polyoxyethylene C_1-6Alkyl ether (polyoxyethylene C_1-4Alkyl ethers), polyoxyethylene C_8-12Alkyl phenyl ether is included.
[0030]
The number average molecular weight of the polyoxyalkylene compound is about 100 to 1500, preferably about 200 to 1200, and more preferably about 200 to 1000.
[0031]
[Production method]
The emulsifiable polyisocyanate having an allophanate group of the present invention can be obtained according to a conventional method of reacting an isocyanate and a hydroxy compound. For example, the allophanate group-containing polyisocyanate and a hydrophilic compound (polyoxyethylene chain) can be obtained. Containing compound) can be obtained by reacting with stirring.
[0032]
The reaction temperature is not particularly limited, and is usually about 50 to about 90 ° C. The reaction time is not particularly limited, and is, for example, about 1 to 24 hours, preferably about 1 to 8 hours. The reaction may be performed in the presence of a catalyst (such as an amine catalyst or a tin catalyst). The reaction may be performed in the presence of a solvent inert to the reaction, but is usually performed in the absence of a solvent. Examples of the inert solvent include hydrophilic or water-soluble solvents that are non-reactive with isocyanate groups, for example, ketones such as acetone; ethers such as dioxane and tetrahydrofuran; ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl Examples include cellosolve acetates and carbitol acetates such as ether acetate, diethylene glycol ethyl ether acetate, and diethylene glycol butyl ether acetate; nitrogen-containing solvents such as N-methylpyrrolidone and N-methylcaprolactam; and mixed solvents thereof.
[0033]
The reaction is usually performed in an inert gas (nitrogen gas, argon gas, helium gas, etc.) atmosphere or under circulation.
[0034]
The ratio of the allophanate group-containing polyisocyanate and the hydrophilic compound is 0.01 to 0.034 equivalents, preferably 0.015 to 0.03 equivalents of the active hydrogen atom of the hydrophilic compound with respect to 1 equivalent of the isocyanate group in the polyisocyanate. About 03 equivalents.
[0035]
The ratio of free isocyanate groups in the obtained allophanate group-containing emulsifiable polyisocyanate is, for example, about 10 to 30% by weight, preferably about 11.5 to 21.5% by weight in the reaction mixture containing the emulsifiable polyisocyanate. Usually, it is about 15 to 23% by weight.
[0036]
The reaction usually involves mixing (preparing) the allophanate group-containing polyisocyanate and the polyoxyethylene chain-containing compound in such a ratio that the free isocyanate group content in the self-emulsifying polyisocyanate to be produced falls within the above range. It is preferable to carry out.
[0037]
The ratio of the hydrophilic part (polyoxyalkylene chain, especially polyoxyethylene chain) in the obtained allophanate group-containing emulsifiable polyisocyanate can be selected from a wide range, for example, 1 to 15% by weight, preferably 1 to 1% by weight. The amount is about 10% by weight, more preferably about 1 to 5% by weight, and usually about 3 to 7% by weight. If the ratio is too small, the emulsifying power may be reduced, and if it is too large, the hydrophilicity will be too high, and the pot life may be shortened or the physical properties such as water resistance may be reduced.
[0038]
The self-emulsifying polyisocyanate of the present invention is liquid at a solid content of 100% by weight. That is, the viscosity of the solid content at 25 ° C. is 1000 mPa · s or less from the viewpoint of permeability and impregnation into the porous substrate, and usually has fluidity at room temperature. In particular, in addition to the permeability and impregnation properties with respect to the porous substrate, the viscosity (25 ° C.) of the self-emulsifiable polyisocyanate (solid content) from the viewpoint of the reinforcing effect and the water-stopping effect in the surface layer of the porous substrate, About 50 to 1000 mPa · s (for example, 50 to 800 mPa · s), preferably about 50 to 700 mPa · s (for example, 100 to 600 mPa · s), and usually about 100 to 550 mPa · s. Moreover, even if the emulsifiable polyisocyanate has a solid content of 100% by weight, it has high emulsifiability with respect to water, an aqueous solvent, or a non-resinous aqueous dispersion (particularly water). Therefore, it can be efficiently emulsified and dispersed by adding to an aqueous solvent such as water without using an organic solvent, and contamination of the coating solution by the organic solvent can also be suppressed. If necessary, it may be used in combination with an aqueous resin composition (in particular, an aqueous resin composition that is non-reactive with an isocyanate group).
[0039]
The self-emulsifiable polyisocyanate thus obtained has good water dispersibility or water solubility, and when added to an aqueous solvent (especially water), it can be easily obtained in a short time without requiring a strong stirring force. And can be uniformly dispersed or emulsified. Moreover, it is highly stable in water. Therefore, it can be suitably used as a surface coating agent or a base treatment agent for various base materials (paper, wood, metal, plastic, inorganic material, etc.), a binder for impregnation processing or binding of paper or fiber, and the like.
[0040]
The polyisocyanate of the present invention has a high penetration or impregnation property into a porous substrate and a long pot life. Furthermore, the reinforcement with respect to the surface layer of a porous base material is remarkable, and the hardened | cured material with little discoloration by a heat | fever or light can be formed. Moreover, since it does not contain a volatile organic solvent, it is excellent in terms of safety and health. Therefore, the polyisocyanate can be effectively used as an aqueous base treatment agent (such as an aqueous sealer composition) such as various porous substrates or building materials (such as building materials for interior and exterior buildings).
[0041]
[Pretreatment method of porous substrate]
In the present invention, by applying (or impregnating) an aqueous coating agent (aqueous sealer, aqueous composition, etc.) containing the allophanate group-containing emulsifying polyisocyanate to the porous substrate, the base treatment of the porous substrate is performed. It can be performed.
[0042]
The porous substrate is not particularly limited and may be an organic substrate composed of paper, cloth, resin or the like, but is usually an inorganic substrate. Above all, at least the surface is capable of water permeation or permeation, and the substrate has pores that are inhibited from permeation or permeation of the resin (polymeric substance). And a substrate that requires a ground treatment.
[0043]
The inorganic porous substrate may be a member constituting a road surface, a wall surface (for example, a punched concrete surface, a brick, etc.), and is usually a plate shape or panel shape (flat plate, corrugated plate, flexible plate) used for building materials. It may be a porous substrate such as a plate or a soft plate. Such a substrate may contain inorganic particles, inorganic fibers and the like, and is composed of at least a hydraulic inorganic component (cement, gypsum, silicate, etc.). Examples of the substrate include calcium silicate board, wood reinforcing cement (wood wool cement board, asbestos slate / wood wool cement plywood, wood chip cement board, pulp cement board, etc.), fiber reinforced cement board (glass fiber reinforced cement board, etc.) ), Mortar board, cement perlite board, rock wool board, gypsum mineral board (gypsum board, gypsum board, etc.), concrete, foamed cellular concrete, lightweight cellular concrete (ALC (autoclaved light-weight concrete) board), fiber reinforced concrete (Concrete reinforced with inorganic fibers such as asbestos slate, steel fibers, glass fibers, carbon fibers; concrete reinforced with organic fibers such as aramid fibers and polyethylene fibers).
[0044]
The bulk specific gravity (bulk density) of the inorganic porous substrate is, for example, 0.3 to 10 g / cm.^Three(For example, 0.3-5 g / cm^Three), Preferably 0.5-3 g / cm^ThreeDegree.
[0045]
Such an inorganic porous substrate has a rough surface, and the powdery material is easily peeled off. Therefore, the strength of the surface is low, and the adhesion with a top coating agent (or finishing agent) such as a coating agent (paint or the like) or an adhesive is low. When such a base material is ground-treated with the polyisocyanate aqueous coating liquid of the present invention, the surface of the base material is closed while the pores on the surface of the base material are closed with the cured product of the polyisocyanate, and the base material is waterproofed. In addition, since a coating film is not substantially formed on the surface of the base material, finishing processability (adhesion with the top coating film, etc.) is not hindered.
[0046]
An allophanate group-containing self-emulsifying polyisocyanate and an aqueous solvent are mixed to prepare an emulsified aqueous coating agent (aqueous coating liquid), which can be applied or impregnated on a porous substrate. If the aqueous coating solution is left for a long time, usually the isocyanate group reacts gradually with water to produce urea with a higher molecular weight, resulting in a decrease in permeability to the substrate or formation of a coating on the substrate surface. Thus, the adhesiveness (finishing property) with the top coat film is reduced. However, the polyisocyanate of the present invention has a stable free isocyanate group even in an aqueous coating solution and has a long pot life (pot life). For example, 90% or more of isocyanate groups remain even after being left in a closed system for 5 hours or more, and can be effectively used as a coating agent for sealers. Therefore, polyisocyanate and an aqueous solvent may be mixed prior to application at the construction site.
[0047]
Examples of the aqueous solvent include a mixture of water and a water-miscible organic solvent. Examples of such organic solvents include water-miscible organic solvents that are non-reactive with isocyanate groups, such as the cellosolve acetates and carbitol acetates; ketones such as acetone and methyl ethyl ketone; and lower alcohols such as methanol and ethanol. A nitrogen-containing solvent such as N-methylpyrrolidone or N-methylcaprolactam; or a mixed solvent thereof. The ratio of the organic solvent to water is the former / the latter (weight ratio) = 0/100 to 50/50, preferably 1/99 to 30/70, more preferably about 5/95 to 20/80. As the dilution solvent, water is usually used.
[0048]
In the aqueous coating solution, the ratio of the allophanate group-containing self-emulsifying polyisocyanate and the solvent (particularly water) is the former / the latter (weight ratio) = 10/90 to 90/10, preferably 12/88 to 80/20, More preferably, it is about 14/86 to 70/30.
[0049]
A viscosity adjusting agent may be added to the aqueous coating liquid, and a conventional viscosity reducing agent (such as an alkylene carbonate such as propylene carbonate) may be added in order to reduce the viscosity and improve the emulsifiability. . In addition, you may use the coating agent (sealer etc.) which already added the viscosity reducing agent.
[0050]
The aqueous coating solution may contain a conventional additive, for example, a coating property improving agent, a coloring pigment, an antifoaming agent, a surfactant and the like, if necessary.
[0051]
Application of the aqueous coating liquid is sufficient if it can penetrate or impregnate at least the surface of the porous substrate. Conventional application such as roller coating (sponge roll coater coating, etc.), brush coating, spray coating, rubber rake coating, etc. A method can be adopted, and the substrate may be immersed in an aqueous coating solution.
[0052]
The coating amount or impregnation amount of the aqueous coating liquid varies depending on the kind of porous substrate, porosity, bulk specific gravity, etc., but is usually 5 to 300 g / m in terms of solid content.², Preferably 10 to 200 g / m²More preferably, it is 10-100 g / m²Degree.
[0053]
The substrate coated with the aqueous coating solution may be dried by heating after coating, but can usually be dried at room temperature. For example, it can be dried at room temperature for about 0.5 to 4 hours, preferably about 0.5 to 2 hours.
[0054]
In the present invention, the porous substrate can be effectively ground-treated by diluting the self-emulsifying polyisocyanate having an allophanate group with water to form an aqueous coating solution and impregnating or infiltrating the porous substrate. Therefore, when the polyisocyanate of the present invention is used as a base treatment agent, the permeability and impregnation property of the base treatment agent with respect to the porous substrate can be improved.
[0055]
【The invention's effect】
Since the polyisocyanate for aqueous coating liquid of the present invention has an allophanate group and self-emulsifying property, it has high permeability to a porous substrate and is suitable for processing. Moreover, when the porous substrate is ground-treated using an aqueous coating solution diluted with water, the strength and water stopping performance of the surface layer of the porous substrate can be improved without impairing the adhesion to the finishing agent. The polyisocyanate can improve pot life even when used as an aqueous treatment agent or an aqueous composition.
[0056]
【Example】
Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples. In Examples and Comparative Examples, “parts” and “%” are in principle based on weight.
[0057]
Synthesis example 1
[Synthesis of self-emulsifiable polyisocyanate A]
A four-necked flask equipped with a stirrer, a thermometer, and a reflux condenser was charged with 100 parts of an HDI-based allophanate group-containing polyisocyanate (trade name: Takenate D-178N, manufactured by Mitsui Takeda Chemical Co., Ltd.) While stirring, 5 parts of methoxypolyethylene glycol (number average molecular weight 400) was added at 70 ° C. The resulting mixture was then heated to 80 ° C. and stirred for 3 hours. After the reaction mixture was cooled to room temperature, a substantially colorless and transparent polyisocyanate A was obtained. Polyisocyanate A had an isocyanate group content of 18.0% by weight and a viscosity of 110 mPa · s (25 ° C.).
[0058]
Synthesis example 2
[Synthesis of self-emulsifiable polyisocyanate B]
In Synthesis Example 1, a substantially colorless and transparent polyisocyanate was prepared in the same manner as in Synthesis Example 1, except that 5 parts of polyoxyethylene nonylphenyl ether (EO chain unit 16) was used instead of 5 parts of methoxypolyethylene glycol. B was obtained. Polyisocyanate B had an isocyanate group content of 18.2% by weight and a viscosity of 130 mPa · s (25 ° C.).
[0059]
Synthesis example 3
[Synthesis of self-emulsifiable polyisocyanate C]
In Synthesis Example 1, instead of 100 parts of the allophanate group-containing polyisocyanate based on HDI, allophanate group and isocyanurate group-containing polyisocyanate based on HDI (trade names: Takenate D-177N, Mitsui Takeda Chemical Co., Ltd.) (Product made) Except using 100 parts, operation similar to the synthesis example 1 was performed, and the polyisocyanate C was obtained. Polyisocyanate C had an isocyanate group content of 19.0% by weight and a viscosity of 300 mPa · s (23 ° C.).
[0060]
Synthesis example 4
[Synthesis of self-emulsifiable polyisocyanate D]
In Synthesis Example 3, the same operation as in Synthesis Example 3 was carried out except that 5 parts of polyoxyethylene nonylphenyl ether (EO chain unit 16) was used instead of 5 parts of methoxypolyethylene glycol. Isocyanate D was obtained. Polyisocyanate D had an isocyanate group content of 19.7% by weight and a viscosity of 540 mPa · s (25 ° C.).
[0061]
Synthesis example 5
[Synthesis of self-emulsifiable polyisocyanate E]
In Synthesis Example 1, instead of 100 parts of the allophanate group-containing polyisocyanate based on HDI, isocyanurate group-containing polyisocyanate based on HDI (trade name: Takenate D-170N, manufactured by Mitsui Takeda Chemical Co., Ltd.) 100 Except using the part, the same operation as in Synthesis Example 1 was performed to obtain polyisocyanate E. The isocyanate group content of polyisocyanate E was 19.3% by weight, and the viscosity 2100 was mPa · s (25 ° C.).
[0062]
Synthesis Example 6
[Synthesis of self-emulsifiable polyisocyanate F]
In Synthesis Example 5, the same operation as in Synthesis Example 5 was carried out except that 5 parts of polyoxyethylene nonylphenyl ether (EO chain unit 16) was used instead of 5 parts of methoxypolyethylene glycol. Isocyanate F was obtained. Polyisocyanate F had an isocyanate group content of 19.9% by weight and a viscosity of 2500 mPa · s (25 ° C.).
[0063]
Synthesis example 7
[Synthesis of self-emulsifiable polyisocyanate G]
A four-necked flask equipped with a stirrer, thermometer, and reflux condenser was charged with 90 parts of polymeric MDI (trade name: Millionate MR200, manufactured by Nippon Polyurethane Industry Co., Ltd.) at 40 ° C. with stirring, at methoxypolyethylene. 10 parts of glycol (number average molecular weight 400) was added. The mixture was then heated to 60 ° C. and stirred for 3 hours. After the obtained reaction mixture was cooled to room temperature, a brownish transparent polyisocyanate G was obtained. Polyisocyanate G had an isocyanate group content of 26.1% by weight and a viscosity of 320 mPa · s (25 ° C.).
[0064]
Synthesis example 8
[Synthesis of self-emulsifiable polyisocyanate H]
In Synthesis Example 7, the same operation as in Synthesis Example 7 was performed except that 10 parts of polyoxyethylene nonylphenyl ether (EO chain unit 16) was used instead of 10 parts of methoxypolyethylene glycol, and a brown transparent polyisocyanate H Got. Polyisocyanate H had an isocyanate group content of 27.0% by weight and a viscosity of 680 mPa · s (25 ° C.).
[0065]
Example 1
By adding 18 parts of polyisocyanate A to 100 parts of water and manually stirring for 5 seconds using a glass rod, an aqueous sealer in which polyisocyanate A is uniformly dispersed is prepared, and the emulsifiability of polyisocyanate is visually observed. Confirmed with. Subsequently, the obtained aqueous sealer was applied to a calcium silicate plate base material at a coating amount of 20 g / m.²Then, the coating was allowed to stand at room temperature for 1 hour, and then the state of the substrate surface was observed to evaluate the permeability. A photograph showing the state of the substrate surface after standing at room temperature for 1 hour is shown in FIG. In FIG. 1, the part enclosed with the broken line shows that it is the part which applied the sealer. Furthermore, it apply | coated to the base material for every fixed time, and the pot life in the emulsified state was evaluated from the permeability | transmittance to a base material.
[0066]
  Example 2Reference examples 1 and 2Comparative Examples 1 to 4
  Evaluation was performed in the same manner as in Example 1 using polyisocyanates B to H.
[0067]
In addition, evaluation of the emulsifiability, the permeability to the base material, and the pot life in the emulsified state in Examples and Comparative Examples was performed as follows.
[0068]
(1) Polyisocyanate emulsifiability
The state of the mixed solution immediately after mixing with water was evaluated visually according to the following criteria.
[0069]
×: non-uniform or partially settled
○: Uniformly dispersed
(2) Permeability to substrate
The state of the substrate surface was evaluated according to the following criteria based on the dryness to touch.
[0070]
×: Tucked by finger touch
△: Slightly tucked by finger touch
○: No tactile touch
(3) Pot life in emulsified state
Evaluation was made according to the following criteria.
[0071]
×: Denatured by reaction with water and could not penetrate into the substrate
Δ: Reaction with water started but could penetrate into the substrate
○: It was able to penetrate into the base material in an unreacted state
The results are shown in the table.
[0072]
[Table 1]

[0073]
  As is apparent from FIGS. 1 to 8, in Comparative Examples 1 and 2, the coating film remains thinly and uniformly on the surface of the substrate. In Comparative Examples 3 to 4, the penetration is partially or totally. A thick and glossy resinous film was formed. ExamplesAnd reference examplesThen, in the photograph, the shade of the calcium silicate plate as the base appeared, and no substantial difference was observed between the coated part and the uncoated part.
[Brief description of the drawings]
FIG. 1 is a photograph showing the results of permeability of a sealer in Example 1. FIG.
[FIG. 2] FIG.Reference example 1It is a photograph which shows the result of the permeability | transmittance of the sealer.
FIG. 3 shows an embodiment.2It is a photograph which shows the result of the permeability | transmittance of the sealer.
FIG. 4 showsReference example 2It is a photograph which shows the result of the permeability | transmittance of the sealer.
FIG. 5 is a photograph showing the result of the permeability of the sealer in Comparative Example 1.
FIG. 6 is a photograph showing the result of the permeability of the sealer in Comparative Example 2.
FIG. 7 is a photograph showing the result of the permeability of the sealer in Comparative Example 3.
FIG. 8 is a photograph showing the result of the permeability of the sealer in Comparative Example 4.

Claims (5)

A porous substrate undercoating method for applying an aqueous coating agent containing an emulsifiable polyisocyanate having an allophanate group to a porous substrate, comprising an allophanate group-containing polyisocyanate and 5 to 12 oxyethylene units the obtained by the reaction of a polyoxyethylene _{C 1-6} alkyl ethers having, Ri viscosity of solids 50~550mPa · s der at 25 ° C., the proportion of free isocyanate groups with 18.0 to 30 wt% A porous base material composed of at least a hydraulic inorganic component and an aqueous coating agent containing a certain emulsifying polyisocyanate and water in a ratio of the former / the latter (weight ratio) = 12/88 to 90/10. A surface treatment method for a porous substrate to be applied . The processing method of Claim 1 using the emulsifiable polyisocyanate which contains a polyoxyethylene chain in the ratio of 1 to 15 weight%. The processing method of Claim 1 using the emulsifiable polyisocyanate which contains an allophanate group and an isocyanurate group in the ratio of the former / the latter (molar ratio) = 100 / 0-20 / 80. Processing method according to claim 1, wherein the use of emulsifiable polyisocyanate containing polyoxyethylene chains in a proportion of 1-10 wt%. The emulsifiable polyisocyanate with water, the former / the latter (weight ratio) = 14/86 processing method according to claim 1, wherein using an aqueous coating agent in a proportion of 90/10.

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