JP2006124660A - Water-based resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an water-based resin composition that has no adverse effect on the environment, does not impair characteristics of a siloxane bond-containing inorganic curable composition, has no problem of crack occurrence after curing, is inexpensive, has normal-temperature curability and causes no remarkable change in physical properties by glass transition in a normal-temperature use range while retaining properties of a conventional organic coating film. <P>SOLUTION: The water-based resin composition comprises water-dispersible colloidal silica, a polar group-containing silane coupling agent, a polyisocyanate compound and an aqueous binder as essential components. Preferably the water-based resin composition comprises 1-5 parts by mass of the silane coupling agent, 0.5-100 parts by mass of the polyisocyanate compound and 10-1,000 parts by mass of the aqueous binder based on 100 parts by mass of the water-dispersible colloidal silica. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an inorganic-organic composite aqueous resin composition that can be used as a coating material.

Conventionally, paints used around living environments such as buildings, building materials, metals, and woodwork are mainly organic resin compositions such as alkyd, acrylic, epoxy, and urethane. In addition, acrylic silicone resin-based and fluororesin-based compositions are used as high weather resistance grades, but most of them are solvent-soluble, which are undesirable for the environment, and have dirt and scratches at the initial stage of curing. There is a problem that it is easy.
Acrylic emulsion resins that have been used for interior and exterior of buildings are water-dispersed and environmentally friendly, but they are inferior in weather resistance and coating strength, easily soiled, easily damaged, and easily deteriorated by light. I have a problem.

  Therefore, in order to solve these problems, a thermosetting resin composition including a resin having a hydroxyl group such as a polyol, an alkoxysilyl group-containing copolymer, and a curing catalyst has been proposed (see Patent Document 1). ). However, this thermosetting resin composition has a problem that its water resistance and chemical resistance are not sufficient and it is easily attacked by water and solvents, and heating at 55 to 350 ° C. is required for curing.

  Further, a curable composition (for example, see Patent Document 2) in which a zirconium chelate compound is blended with a copolymer of an alkoxysilyl group-containing vinyl monomer and an alicyclic epoxy group-containing vinyl monomer has been proposed. However, this curable composition has a problem of poor weather resistance and low-temperature curability.

  And many of the said resin has a remarkable glass transition temperature in 20 to 50 degreeC vicinity which is a use area | region, and raise | generates the remarkable change of a physical property before and behind a glass transition temperature. Because of this, in these organic coatings, although a uniform coating is formed at the time of painting, expansion, cracking, peeling, abrasion, external stimuli such as temperature, humidity, rainfall, skin and plastic contact, Degradation of the coating progresses, such as the infiltration of contaminants and dirt on the hands.

  In recent years, an inorganic curable composition using an organopolysiloxane having a siloxane bond in the basic skeleton has been proposed as a solution to various problems in the organic curable resin composition as described above. Since the formed cured film has excellent performance in terms of surface hardness, heat resistance, weather resistance, chemical resistance, etc., it has begun to be used not only in heat resistant applications but also in the field of construction. However, the curable composition using the organopolysiloxane is different from the organic curable resin composition, and has a brittleness resistance, a crack resistance, an alkali resistance, a shrinkage resistance, etc. due to its crosslinking density. In that respect, its performance is inferior and high temperature curing is required.

  On the other hand, a solvent-free, one-pack type room-temperature-curing organopolysiloxane composition having a liquid organopolysiloxane, a cross-linking agent composed of an organometallic compound, and a curing catalyst composed of a metal-containing compound as essential components has been proposed. (See Patent Document 3). However, in this solvent-free one-component room-temperature-curing organopolysiloxane composition, there is substantially no use such as using a volatile monomer as a cross-linking agent or using alcohol to delay the curing rate. It is difficult to say that it is a solvent. In addition, in the curable composition using this type of organopolysiloxane, it is considered difficult to solve the problem of cracking after curing during thick coating or contact with high concentration organic acid. Is still left. Moreover, it is also true that these organopolysiloxane resins are generally expensive and difficult to use for general purposes.

  Patent Document 4 discloses an invention in which acicular inorganic material is added as a filler to alkoxysilane to prevent cracks, and Patent Documents 5 and 6 disclose cracks by adding alkali titanate fiber to inexpensive colloidal silica. Although the invention to prevent is disclosed, the former has a problem that a large amount of alcohol is generated and is not preferable for the environment, and the latter alkali titanate fiber exhibits a catalytic function by light and deteriorates an organic binder component. is doing.

  On the other hand, Patent Document 7 proposes an inorganic paint having hydrophilicity and crack resistance by adding a specified amount of mica, talc, glass flake or sepiolite to water-dispersed colloidal silica. It has low film properties and substantially contains pigments, so it is inferior in transparency and smoothness of the coating film, difficult to gloss, and it is difficult to say that it has improved the problem of microcracks caused by various external stimuli. .

  In other words, the curable compositions proposed so far are excellent in surface hardness, surface tack, heat resistance, stain resistance, stain resistance removal, and weather resistance, and have room temperature curability. In particular, an aqueous curable resin composition that does not exhibit a remarkable glass transition temperature in the range of 0 ° C. to 70 ° C. has not been put to practical use in organic systems. On the other hand, in inorganic systems, there are no problems of film formation, impact resistance, and crack generation due to various external stimuli, and a substantially aqueous curable resin composition having room temperature curing is still in practical use. It has not been.

Japanese Unexamined Patent Publication No. 1-141952 JP-A 63-108049 Japanese Patent Laid-Open No. 5-247347 JP-A-1-163275 Japanese Patent Publication No. 7-81096 Japanese Patent Publication No. 8-27424 JP 2003-55581 A

  The present invention does not adversely affect the environment, and does not impair the characteristics of the inorganic curable composition having a siloxane bond, and has been considered to be a difficult problem to be solved in this type of inorganic curable composition. There is no problem of generation, it is inexpensive, it has room temperature curability, it retains various physical properties of conventional organic coatings, and it does not cause significant change in physical properties due to glass transition in the room temperature use range. An object of the present invention is to provide a curable resin composition (aqueous resin composition).

  As a result of intensive studies to solve the above-mentioned problems, the inventors of the present invention have a water-based resin that is mainly composed of water-dispersed colloidal silica and that can act on a silane coupling agent having a polar group and simultaneously form a hydrogen bond with colloidal silica. It was found that an inorganic-organic hybrid type resin composition obtained by crosslinking a main ingredient formulated with a polyisocyanate-based curing agent capable of reacting with these multi-component main ingredients can solve the above problems at a high level. The present invention has been completed. Specifically, the present invention is the following <1> to <6>.

<1> An aqueous resin composition comprising water-dispersed colloidal silica, a silane coupling agent having a polar group, a polyisocyanate compound, and an aqueous binder as essential components.
<2> 1-100 parts by mass of the silane coupling agent, 0.5-100 parts by mass of the polyisocyanate compound, and 10-1000 parts by mass of an aqueous binder with respect to 100 parts by mass of the water-dispersed colloidal silica. The aqueous resin composition as described in <1>, characterized by comprising.

<3> The aqueous resin composition according to <2>, wherein the aqueous binder is a binder having a polar bond capable of forming a hydrogen bond with silanol.
The aqueous binder is preferably one or more binders selected from the group consisting of polyurethane, polyamide, polyurea and polyoxazoline.

<4> The aqueous resin composition according to <3>, which does not exhibit a remarkable glass transition temperature in the range of 0 ° C to 70 ° C.
<5> The aqueous resin composition according to any one of <1> to <4> used for forming a cured film, wherein the cured film formed thereby is substantially colorless and transparent. An aqueous resin composition.

  According to the aqueous resin composition of the present invention or the coating comprising the aqueous resin composition, the colloidal silica base material, the silane coupling agent, and the organic aqueous resin are integrated into a hybrid structure, which is highly transparent and has a normal temperature. The glass transition temperature is not at least prominent above, there is no deterioration in physical properties in the operating temperature range, low temperature sensitivity, excellent water resistance and solvent resistance, high breathability, low contamination and weather resistance. It is possible to form a cured film (coating film) that is excellent and resistant to contamination. Therefore, it is a coating solution that is suitably used as a surface protection film for architecture, civil engineering, various inorganic materials or organic materials, and is basically water-based, forming a transparent hybrid silica film that is safe in the manufacturing process and is not limited in its use. can do. Moreover, it is much cheaper than the coating liquid using the conventional alkoxysilane.

Hereinafter, the aqueous resin composition of the present invention will be described in detail.
In the present invention, an expensive alkoxysilane is not used as a main raw material, an inexpensive colloidal silica is used as a resin skeleton, and a silane coupling agent having a polar group, a polyisocyanate compound, and an aqueous binder are essential components of the present invention. The aqueous resin composition is constituted.

When the aqueous resin composition of the present invention is used as a paint and a coating film is formed thereby, a silane coupling agent having a polar group acts on colloidal silica to form a resin skeleton, and this and an aqueous binder are curing agents. An inorganic siloxane-organic hybrid resin composition crosslinked and integrated with a certain polyisocyanate compound is formed. Such a coating film is substantially colorless and transparent, and improves the problems in the inorganic paint and the problems in the organic paint in a mutually complementary manner.
Hereinafter, each component will be described.

(Water-dispersed colloidal silica)
The water-dispersed colloidal silica used in the present invention (hereinafter sometimes simply referred to as “colloidal silica”) is an aqueous silica sol in which fine particles of high molecular weight silicic acid are dispersed in water, and has a particle size in the range of 10 to 30 nm. The thing of the range of hydrogen ion concentration (pH) 8-11 is preferable. For those with a large particle size of 50 nm or more and those with a hydrogen ion concentration in the acidic range, the former is disadvantageous for transparency of the coating film and the latter is disadvantageous for stability. However, it is not preferable. The non-volatile content is generally 20 to 30%, but 40% and 50% products are also commercially available, and the higher non-volatile content is preferable because the solid content when used as a paint is improved. .

(Silane coupling agent)
The silane coupling agent used in the present invention is a product to be added to act on colloidal silica, and as a result has a polar group that reacts with the polyisocyanate compound that is a cross-linking agent. Not. Specifically, for example, a silane coupling agent having a ureido group, an amino group, or a thiol group, or a silane coupling agent having an epoxy group or an alicyclic epoxy group can be used. These groups may be added directly to the colloidal silica, or may be added after hydrolysis with a dilute acid in advance.

  The amount of the silane coupling agent to be added is not limited as long as a part of the surface of the colloidal silica as a substrate can be modified with a polar group that reacts with isocyanate, and preferably 100 parts by mass of colloidal silica. 1-50 mass parts, More preferably, it is 5-20 mass parts, More preferably, it is 8-10 mass parts. If the amount added is too large, the alcohol produced by hydrolysis degrades the stability of the system and, as a result, becomes expensive.

(Polyisocyanate compound)
The polyisocyanate compound used in the present invention is a product added as a curing agent, and is generally not limited as long as it is a self-emulsifying polyisocyanate that can be blended in an aqueous paint.

  If 1 part of polyisocyanate is reacted with a polyol component such as polyethylene glycol or polypropylene glycol or water, it is a curing agent that can also serve as an aqueous binder described later. That is, a part of polyisocyanate is urethanized and buretted with polyglycol, water, etc., and this part interacts with SiOH on the surface of colloidal silica, which is a base material, by hydrogen bonding and stabilized, thereby colloidal silica- The aqueous resin is completed with a silane coupling agent-polyisocyanate resin. In this case, the polyisocyanate-based resin (polyisocyanate compound) serves as an aqueous binder that is an essential component of the present invention, and the structure is also included in the concept of the present invention.

  The compounding amount of the polyisocyanate-based resin may be 0.5 to 100 parts by mass with respect to 100 parts by mass of the water-dispersed colloidal silica, and the addition amount is properly used depending on the application. In addition, what is necessary is just to determine a compounding quantity within the range of 10-1000 mass parts with respect to 100 mass parts of water-dispersed colloidal silica, when serving also as an aqueous binder.

(Water-based binder)
The aqueous binder used in the present invention is added to form a hydrogen bond with the base colloidal silica, and can form a hydrogen bond with silanol on the surface of the colloidal silica such as polyurethane, polyamide, polyurea, polyoxazoline, and poval. Any type of binder can be used as long as it has a polar bond. Any film may be used as long as it improves the film-forming property of colloidal silica, prevents cracks, and forms a coating film integrated with the base material colloidal silica, particularly inducing an extreme glass transition in the range of 0 ° C to 70 ° C. What is not a thing is preferable, More preferably, what has a glass transition temperature (Tg) at 0 degrees C or less is good, and the urethane resin which has Tg at -50 degrees C or less is especially preferable.

  The addition amount of the aqueous binder may be an addition amount that does not impair the physical properties of the colloidal silica that is the base material, and is preferably 10 to 1000 parts by mass, more preferably 50 to 500 parts per 100 parts by mass of the colloidal silica. Part by mass, more preferably 80 to 200 parts by mass, and most preferably 100 to 150 parts by mass. If the blending ratio of the aqueous binder is less than 10 parts by mass, the film-forming property is deteriorated and cracks easily occur, and if it exceeds 1000 parts by mass, the physical properties derived from colloidal silica are difficult to be exhibited.

(Other ingredients)
Other components that can be blended in the aqueous resin composition of the present invention include resin emulsions other than the above-mentioned aqueous binders, organic binders such as non-polyisocyanate curing agents, wax emulsions, inorganic binders such as metal alkoxides and alkali silicates, and curing acceleration. Agents, thickeners, antifoaming agents, surface conditioning agents, color pigments, extender pigments, fibers, and the like, and these can be blended without departing from the object of the present invention.

(Manufacture, application, effects, etc. of aqueous resin compositions)
For the production of the aqueous resin composition or paint of the present invention, a usual method for producing a water-based paint can be employed.
As a coating method when the aqueous resin composition of the present invention is used as a paint, it is an undiluted solution or diluted with a dispersion medium such as water if necessary, and then an aqueous brush, a roll brush, an air spray, It can be applied by airless spray. The thickness of the coating film formed at this time is preferably about 20 to 50 μm in terms of dry film thickness. The hybrid aqueous resin composition or paint of the present invention is cured at room temperature, but can be baked and cured at an appropriate temperature.

The aqueous resin composition or paint of the present invention has respirability by the action of the colloidal silica contained, can be applied to the respirable substrate, does not inhibit the respirability of the substrate, and the substrate contains moisture But it can be finished evenly without blistering and blistering.
The aqueous resin composition or paint of the present invention has the advantage of excellent permeability and adhesion to inorganic materials, metals, wood, plastics, cloth, paper, and the like due to the action of the colloidal silica contained therein.

  In the aqueous resin composition or paint of the present invention, it is sufficient that all components are mixed at the time of use. For example, in the distribution stage of a product as a paint, each component is divided into two liquids for the purpose of ensuring liquid stability. It may be set as the state divided above, and may be used by mixing at the stage of use. In this case, what kind of combination is used as another liquid may be appropriately selected in view of the purpose. For example, it is exemplified that a polyisocyanate compound and an aqueous binder are separated from each other. Is done.

The water-based resin composition or paint of the present invention has a surface hydrophilicity due to the action of the colloidal silica contained therein, and has a self-cleaning property for washing away surface dirt with rainwater when applied outdoors.
The aqueous resin composition or paint of the present invention preferably does not exhibit a remarkable glass transition temperature in the normal temperature range of 0 ° C. to 70 ° C., in which case there is little decrease in physical properties in the use temperature range, and cracks, cracks, Resistant to peeling and low in temperature sensitivity, it is possible to form a coating surface that is excellent against contamination.

Next, although an Example and a comparative example are given and this invention is demonstrated concretely, it cannot be overemphasized that this invention is not limited by this.
Table 1 below summarizes the compositions and evaluations of the paints (aqueous resin compositions) of Examples and Comparative Examples.

  According to the composition shown in Table 1, 10 kinds of paints of Examples 1 to 6 and Comparative Examples 1 to 4 were prepared, and the coating film obtained by applying this to the test piece, and the evaluation test described below for the paint itself. Carried out. In this test example, a ureido type silane coupling agent was used, and a urethane emulsion was used as the aqueous binder.

Each component used in this test will be described in detail.
As colloidal silica, silica doll # 50 (manufactured by Nippon Chemical Industry Co., Ltd.) was used. This colloidal silica has an average particle size of 10 to 20 nm, a hydrogen ion concentration (pH) of 9.0 to 10.5, and a non-volatile content (NV) of 50%.

As a ureido type silane coupling agent, A-1160 (manufactured by Nihon Unicar, γ-ureidopropyltriethoxysilane) was used.
As a polyisocyanate compound, Duranate WB40-80D (manufactured by Asahi Kasei, water-dispersed polyisocyanate) was used.

As Urethane Elsion, Adekabon titer HUX232 (Asahi Denka Kogyo, non-yellowing polyester urethane) was used. The glass transition temperature (Tg) of this urethane solution is −60 ° C. or lower.
Further, in some examples, an acrylic emulsion which is an organic binder is blended as another component, and Acryset EMN268E (manufactured by Nippon Shokubai Co., Ltd.) was used for this.

  The acrylic alkyd resin paint used in Comparative Example 2 is an acrylic-futsin type (manufactured by Atomics), the acrylic urethane resin paint used in Comparative Example 3 is floor top # 7000 (manufactured by Atomics), and the epoxy used in Comparative Example 4 The resin paint is Floor Top # 8000 (manufactured by Atomics).

The outline of the evaluation test for each paint or coating film is described below.
(Appearance of coating film)
The appearance of the coating film was visually evaluated according to the following evaluation criteria for each coating film applied and formed on glass as a test piece. At that time, the transparency of the coating film (or its color when opaque) was also evaluated.
-Evaluation criteria-
A: Extremely smooth.
○: Smooth but slightly uneven.
X: No smoothness.

(Glass-transition temperature)
The dynamic viscoelasticity E ′ was measured for each paint by using a dynamic viscoelasticity measuring device RSA-II manufactured by Rheometric Co., and its reduction point was determined, and this was taken as the glass transition temperature.

(Solvent resistance)
Solvent resistance is rubbed 100 times for each coating film that is applied to and formed on a test piece (bonded steel sheet) by impregnating methyl wipes (MIBK) into Kimwipe (trade name, manufactured by Kimberley Clark). The appearance of the coated film after the evaluation was evaluated according to the following evaluation criteria.
-Evaluation criteria-
A: No change.
○: Almost no change.
X: The coating film is dissolved.

(water resistant)
The water resistance was evaluated by immersing a test piece (bonded steel plate) on which each coating film was formed in water for 24 hours, and then evaluating the appearance of the coating film according to the following evaluation criteria.
-Evaluation criteria-
A: No change.
○: Almost no change.
X: Emulsion, dissolution, or blistering occurred.

(Contamination resistance)
Contamination resistance was measured by placing a test piece (bonded steel plate) with each coating film on an exposure table and exposing it on the roof of the building for 6 months, and then evaluating the appearance of the coating film according to the following evaluation criteria.
-Evaluation criteria-
A: No dirt such as rain streaks.
○: There is almost no dirt such as rain streaks.
×: Rain streak traces.

(Tack test)
The paints of Examples and Comparative Examples were applied to test pieces (bonded steel plates) and dried at room temperature and humidity for 24 hours. Thereafter, the carbon surface of the carbon paper was superposed on the coating surface and a 1 kg weight was placed thereon and left at 60 ° C. (tack test 1) or 80 ° C. (tack test 2). After 1 hour, the weight was removed, the carbon paper was peeled off, and the carbon remaining on the coating film was observed and evaluated according to the following evaluation criteria.

-Evaluation criteria-
A: No trace is left.
○: Almost no trace remains.
○ △: A slight mark remains.
Δ: Marks remain clearly.
X: Carbon paper sticks and does not peel off.

(Water vapor permeability)
Each coating film was applied to a fluororesin sheet with a wet film thickness of 125 μm and dried, and this was peeled off. The resulting coating film was in conformity with JIS Z0208 (Method for testing moisture permeability of moisture-proof packaging materials (cup method)). The moisture permeability was measured at a temperature of 23 ° C. and a relative humidity of 90 ± 2%. As a result, the case where it was 50 (g / m ² · 24h) or more was rated as “◯”, and the case where it was less than “×”.

The image figure of the cured film by an aqueous resin composition (Example 3) is put on FIG. In the figure, “NCO prepolymer” means a polyisocyanate compound.
In FIG. 2, the violet laser micrograph of the aggregation surface in the coating film of the comparative example 1 is mounted.

FIG. 3 shows the profiles of dynamic viscoelasticity E ′ and tan δ in the paints of Examples 1, 2, and 3 and Comparative Example 4.
In FIG. 4, the graph which shows the result of the water-vapor-permeability test in the coating film of Example 1 and Comparative Example 3 is put.

<Consideration of results>
When the coating material using the aqueous resin composition of the present invention is used, the resulting coating film has a hybrid structure in which a colloidal silica substrate, a silane coupling agent, and an organic aqueous resin are integrated as shown in the image diagram of FIG. Take. And even from the results of the evaluation test, in the examples, the transparency is high, the glass transition temperature is not higher than normal temperature, there is no deterioration in physical properties in the operating temperature range, the temperature sensitivity is low, water resistance, It was confirmed that it had excellent solvent resistance, high breathability, low contamination, excellent weather resistance, and resistance to contamination.

  On the other hand, in the coating material of Comparative Example 1, the coating film components aggregated after application, and a satisfactory coating film was not obtained. Moreover, in the coating film of the comparative example 2, since coating film strength was low and it was not able to peel off from a test piece, implementation of water-vapor permeability was postponed.

About each coating film of Comparative Examples 2-4, although there are some which have obtained good or relatively good results in any of the evaluation test items, like the composite coating film by the aqueous resin composition of the present invention Nothing is satisfactory for all items.
In addition, about the coating film of Example 6, although there are items which are a little inferior to other examples, this is a characteristic in which the ratio of the aqueous binder to the colloidal silica in the coating composition is slightly high and is derived from the colloidal silica. It seems to be because it is somewhat weak. However, it can be seen that even such a coating film of Example 6 exhibits sufficiently high performance as compared with the comparative example.

  Therefore, the water-based resin composition of the present invention and the coating material obtained therefrom can be suitably used for construction and civil engineering, or as a coating solution for forming a protective film on the surface of various inorganic materials or organic materials. In addition, the aqueous resin composition of the present invention and the coating material thereby are basically aqueous, safe in the production process, and can form a transparent hybrid silica film whose use is not limited. Furthermore, it is much cheaper than a coating solution using a conventional alkoxysilane.

  In addition, about the coating material of Example 1 and the comparative example 2, it applied to the actual stair railing part continuously, and when it was exposed for 6 months and the tack dirt was confirmed, the difference is clear, Comparative example 2 The part painted with the paint of No. 1 was noticeably soiled, but no part of the part painted with the paint of Example 1 was confirmed.

It is an image figure of an aqueous resin composition (Example 3). 2 is a blue laser micrograph (magnification 9000 times) of an aggregated surface of Comparative Example 1. 5 is a profile of dynamic viscoelasticity E ′ and tan δ in each paint of Examples 1, 2, and 3 and Comparative Example 4. It is a graph which shows the result of the water-vapor-permeability test of Example 1 and Comparative Example 3.

Claims (5)

An aqueous resin composition comprising water-dispersed colloidal silica, a silane coupling agent having a polar group, a polyisocyanate compound, and an aqueous binder as essential components. 1 to 50 parts by mass of the silane coupling agent, 0.5 to 100 parts by mass of the polyisocyanate compound, and 10 to 1000 parts by mass of an aqueous binder with respect to 100 parts by mass of the water-dispersed colloidal silica. The aqueous resin composition according to claim 1, wherein The aqueous resin composition according to claim 2, wherein the aqueous binder is a binder having a polar bond capable of forming a hydrogen bond with silanol. The water-based resin composition according to claim 3, which does not exhibit a remarkable glass transition temperature in the range of 0 ° C to 70 ° C. The aqueous resin composition according to any one of claims 1 to 4, which is used for forming a cured film, wherein the cured film formed thereby is substantially colorless and transparent.

Images