JP2016003259A - Aqueous coating composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aqueous coating composition which can be produced at low cost, has excellent stability and can form a coating film having excellent weather resistance and corrosion resistance/rust-proofness.SOLUTION: There is provided an aqueous coating composition which comprises an acrylic resin emulsion as an acrylic resin and an inorganic reactive material prepared by preliminarily mixing water glass and an alkyl silicate, In the mixing ratio of the water glass and the alkyl silicate in the inorganic reactive material, the silica solid content of the water glass is 75 wt.% or more and 90 wt.% or less based on the total amount of the solid content of the alkyl silicate and the silica solid content of the water glass.

Description

The present invention relates to an aqueous coating composition that can improve the corrosion resistance and rust prevention properties of metal surfaces such as automobile parts and building materials, and particularly relates to an aqueous coating composition that is excellent in stability and can be manufactured at low cost. is there.

In recent years, in order to reduce volatile organic compounds (VOC) from the viewpoint of environmental protection, paints used for the surface coating of metal substrates such as automobile parts, home appliances, building materials, etc. Aqueousization is progressing. In addition, as a rust preventive paint, from the viewpoint of global environmental conservation, it is requested to move away from a paint using a rust preventive containing a toxic heavy metal such as a conventional chromium-based rust preventive or lead-based rust preventive.

Paints using epoxy-modified resins that exhibit high rust-proofing properties are used as water-based paints that have rust-proofing properties without using rust-preventing agents containing such toxic heavy metals, but epoxy-modified resin-based coatings Has excellent rust prevention properties, but has disadvantages such as poor weather resistance and high cost.

What attracted attention was the fact that the addition of alkyl silicate to an inexpensive acrylic resin with excellent weather resistance can realize rust prevention equivalent to that of an epoxy-modified resin-based paint.
However, alkyl silicates are highly hydrophobic, have poor compatibility with acrylic resins that are water-based resins, and are easily gelled by hydrolysis and subsequent condensation reactions in water. It does not become a stable paint.

  Here, Patent Document 1 discloses an aqueous resin dispersion in which an organic aqueous resin is combined to ensure long-term stability by emulsifying an organic silicate compound together with an organic aqueous resin. According to Patent Document 1, an inorganic silicon compound having a silanol group can be added as a compound that can be further combined with an organic silicate compound. This is because the inorganic silicon compound having a silanol group is hydrolyzed by water to form a composite with the organic aqueous resin.

JP 2000-053890 A

However, in the technique described in Patent Document 1, an organic silicate compound, and further, an inorganic silicon compound having a silanol group is emulsified and combined with an organic aqueous resin, and due to the nature of emulsification, temperature, viscosity, specific gravity Since it is easily affected by paint preparation conditions such as differences, strict manufacturing control conditions are necessary to stabilize the paint and obtain stable coating film performance. Further, in order to easily emulsify, it is necessary to add a solvent. After emulsification, it is necessary to remove the solvent to remove the solvent, and an inefficient and energy consuming process is required.
For this reason, the technique described in Patent Document 1 requires time and effort for manufacturing.

Then, this invention makes it a subject to provide the water-based coating composition which can be manufactured at low cost and can form the coating film which was excellent in stability, and had the combined weather resistance, corrosion resistance, and rust prevention property. It is.

  The aqueous coating composition of the invention of claim 1 is an aqueous coating composition containing an acrylic resin, an inorganic reaction material prepared by mixing water glass and alkyl silicate, and water as a solvent, the inorganic coating material The silica solid content of the water glass in the reaction material is within the range of 75% by weight or more and 90% by weight with respect to the total amount of the silica solid content of the water glass and the solid content of the alkyl silicate in the inorganic reaction material. is there.

Here, as the “water glass”, a water-soluble silicate using a concentrated aqueous solution of alkali metal silicate (alkali silicate) such as lithium silicate, sodium silicate (sodium silicate), potassium silicate, cesium silicate and the like is used. Above all, since lithium silicate is excellent in adhesiveness, according to the aqueous coating composition containing water glass formed with an aqueous solution of lithium silicate, the strength when coated on the surface to be coated is improved. Also, the adhesion to the painted surface can be improved. Water glass formed with an aqueous solution of sodium silicate or potassium silicate is inexpensive and heat resistant. The type of water glass is selected according to the required coating film performance and the like, and is not limited to one type, and two or more types can be mixed and used.
In addition, the silica solid content of the said water glass is a solid content of the silica component in water glass.

  The aqueous coating composition of the invention of claim 2 is characterized in that the solid content of the acrylic resin is obtained by combining the total amount of the solid content of the silica of the water glass and the solid content of the alkyl silicate with the solid content of the acrylic resin. It is within the range of 80% by weight to 99% by weight with respect to the total weight.

The solvent of the water-based coating composition of the invention of claim 3 is substantially only water except for the solid content.
Here, “the solvent is substantially only water” means that only water is used as the solvent of the water-based coating composition, and no organic solvent is actively used as the solvent. It does not mean that the coating composition does not contain any organic solvent. For example, when an organic solvent is included as an internal solvent in the additive, a small amount of organic solvent is necessarily included in the aqueous coating composition, and a small amount of organic solvent is used to control the surface tension and evaporation rate. However, it is not meant to exclude those cases. That is, although an organic solvent may be included for uses other than the solvent, it means that only water is actively used as the solvent.

  The method for producing an aqueous coating composition of the invention of claim 4 is a method for producing an aqueous coating composition containing an acrylic resin, an inorganic reaction material prepared by mixing water glass and alkyl silicate, and water as a solvent. The silica solid content of the water glass in the inorganic reaction material is 75 with respect to the total amount of silica solid content of the water glass and the solid content of the alkyl silicate in the inorganic reaction material. It is prepared in advance by adjusting and mixing so as to be in the range of not less than 90% by weight and not more than 90% by weight, and then the inorganic reaction material is mixed with the acrylic resin.

  According to a fifth aspect of the present invention, there is provided a method for producing an aqueous coating composition comprising the solid content of the acrylic resin, the silica solid content of the water glass of the inorganic reactant and the total solid content of the alkyl silicate and the solid content of the acrylic resin. It is within the range of 80% by weight or more and 99% by weight or less with respect to the total weight.

  In the method for producing an aqueous coating composition according to the sixth aspect of the invention, the solvent is substantially only water except for a solid content.

  According to the aqueous coating composition of the first aspect of the present invention, the alkyl silicate is mixed with water glass within a predetermined range and contained in the aqueous coating composition as an inorganic reaction material. By disposing water glass in an inorganic reaction material prepared by mixing water glass with an alkyl silicate within a predetermined range, silanol groups possessed by the alkyl silicate (exactly, some of the alkoxysilyl groups of the alkyl silicate are Silica groups of water glass are bonded to silanol groups (-SiOH) generated by hydrolysis upon contact with water, and hydrolysis by the silanol groups of the alkyl silicate and subsequent condensation reaction are suppressed. For this reason, when an alkyl silicate is directly mixed with an acrylic resin, the presence of water usually causes hydrolysis by the silanol groups of the alkyl silicate and subsequent condensation reaction to cause gelation. In the present invention, the alkyl silicate is converted into water. Since it becomes a stable solution state by mixing with glass within a predetermined range to obtain an inorganic reaction material, the stability of the aqueous coating composition is ensured. When this aqueous coating composition is applied to an object to be coated, the water evaporates, so that the bond between the water glass and the silanol group of the alkyl silicate is released, and the hydrolysis and subsequent condensation of the alkyl silicate. The reaction proceeds, and a coating film exhibiting corrosion resistance and rust prevention is formed by the reaction between the alkyl silicate and the acrylic resin, and the weather resistance of the coating film is secured by the acrylic resin having excellent weather resistance.

Here, when the silica solid content of the water glass in the inorganic reaction material exceeds 90% by weight with respect to the total amount of the silica solid content of the water glass of the inorganic reaction material and the solid content of the alkyl silicate, more specifically, the water in the inorganic reaction material When the ratio of the silica solid content (silica component) of the glass is too high relative to the solid content of the alkyl silicate in the inorganic reaction material, the silica component of the water glass cured in the coating film formed by applying the aqueous coating composition. The water resistance is impaired due to the high hydrophilicity of the silica component. On the other hand, when the silica solid content of the water glass is less than 75% by weight based on the total amount of the silica solid content of the water glass of the inorganic reaction material and the solid content of the alkyl silicate (ratio of the silica solid content of the water glass in the inorganic reaction material) Is too low relative to the solid content of the alkyl silicate in the inorganic reaction material), the amount of silica component of the water glass bound to the silanol group of the alkyl silicate is insufficient, and hydrolysis and subsequent condensation reaction proceeds in the alkyl silicate. Gelation, and the stability of the aqueous coating composition deteriorates.
Therefore, by making the silica solid content of the water glass in the inorganic reaction material within the range of 75 wt% or more and 90 wt% or less with respect to the total amount of the silica solid content of the water glass of the inorganic reaction material and the solid content of the alkyl silicate, Ensures the stability of the water-based paint composition, and ensures excellent water resistance in the coating film formed by applying this water-based paint composition. Excellent corrosion resistance and rust prevention by alkyl silicate. The ability to show off.

  And in the water-based coating composition of the present invention, by mixing the alkyl silicate and the water glass to make an inorganic reaction material, the water glass is bonded to the alkyl silicate so that the hydrolysis of the alkyl silicate and the subsequent reaction. Since the gelation due to the progress of the condensation reaction is prevented, the stability of the aqueous coating composition is ensured, and it is not necessary to emulsify the acrylic resin and the alkyl silicate for the stabilization of the aqueous coating composition. There is no need for labor (work) and costs associated with emulsification. Furthermore, acrylic resin, water glass, and alkyl silicate are all materials that can be obtained at low cost. For this reason, an aqueous coating composition can be obtained at low cost.

In this way, the aqueous coating composition can be produced at low cost, and can form a coating film having excellent stability and excellent weather resistance, corrosion resistance and rust resistance.

  According to the aqueous coating composition of the invention of claim 2, the solid content of the acrylic resin is the total weight of the silica solid content of the water glass of the inorganic reactant and the solid content of the alkyl silicate and the solid content of the acrylic resin. On the other hand, it is within the range of 80 wt% or more and 99 wt% or less.

  Here, if the solid content of the acrylic resin exceeds 99% by weight, the amount of the inorganic reaction material (the total amount of the silica solid content of the water glass and the solid content of the alkyl silicate) becomes too small. The effect of improving the corrosion resistance and rust prevention by the alkyl silicate contained in is not obtained. On the other hand, when the solid content of the acrylic resin is as low as less than 80% by weight, the amount of the inorganic reaction material is too high, and the ratio of water glass contained in the inorganic reaction material is increased, thereby increasing the amount of the water-based coating composition. Viscosity increases and stability decreases. In addition, the coating film formed by applying the aqueous coating composition also has a high ratio of hydrophilic water glass, so that the water resistance is lowered and sufficient corrosion resistance and prevention due to the reaction between the alkyl silicate and the acrylic resin. Rust is not exhibited, and the coating film performance is deteriorated.

  Therefore, the solid content of the acrylic resin is 80 wt% or more and 99 wt% or less with respect to the total weight of the silica solid content of the water glass of the inorganic reaction material and the solid content of the alkyl silicate and the solid content of the acrylic resin. If it exists, in addition to the effect of Claim 1, the stability of aqueous coating composition will become high reliably, and the coating film excellent in coating-film performance, such as water resistance, corrosion resistance, and rust prevention property, can be formed.

  According to the aqueous coating composition of the invention of claim 3, since the solvent excluding the solid content is substantially only water, in addition to the effect of claim 1 or claim 2, the volatile organic compound There is almost no fear of generating (VOC), and it becomes an environmentally friendly water-based coating composition. In particular, the present invention is intended to stabilize the aqueous coating composition by preventing the gelation due to the hydrolysis of the alkyl silicate and the subsequent condensation reaction with water glass. Since it is not necessary to emulsify the alkyl silicate, an organic solvent for emulsification is not required, and the water-based coating composition is extremely environmentally friendly.

According to the method for producing a water-based coating composition of the invention of claim 4, the inorganic reaction material is composed of the silica solid content of the water glass in the inorganic reaction material, the silica solid content of the water glass in the inorganic reaction material and the alkyl silicate. It is prepared in advance by adjusting and mixing so as to be 75% by weight or more and 90% by weight or less with respect to the total solid content, and then the inorganic reaction material is mixed with an acrylic resin.
According to the production method of the present invention, since water glass is mixed with alkyl silicate in advance, silanol groups possessed by alkyl silicate (exactly, a part of the alkoxysilyl group of alkyl silicate is hydrolyzed by contact with water). The silica component of the water glass is bonded to the silanol group (-SiOH) generated by the reaction. For this reason, the alkyl silicate usually gels due to the hydrolysis of the silanol groups of the alkyl silicate and the subsequent condensation reaction due to the presence of water, but by mixing with water glass in advance, the silanol of the alkyl silicate Since the silica component of the water glass is bonded to the base and gelation of the alkyl silicate is suppressed, and the inorganic reaction material is in a stable solution state, the aqueous coating composition is maintained in a stable state.
When this aqueous coating composition is applied to an object to be coated, the water evaporates, so that the bond between the water glass and the silanol group of the alkyl silicate is released, and the hydrolysis and subsequent condensation of the alkyl silicate. The reaction proceeds, and a coating film exhibiting corrosion resistance and rust prevention is formed by the reaction between the alkyl silicate and the acrylic resin, and the weather resistance of the coating film is secured by the acrylic resin having excellent weather resistance.

Here, when the silica solid content of the water glass of the inorganic reaction material exceeds 90% by weight relative to the total amount of the silica solid content of the water glass of the inorganic reaction material and the solid content of the alkyl silicate (ratio of the silica component of the water glass) If it is too high), the ratio of the silica component of the cured water glass is increased in the coating film formed by applying the aqueous coating composition, and the water resistance is improved due to the high hydrophilicity of the silica component of the cured water glass. Damaged. On the other hand, when the silica solid content of the water glass is less than 75% by weight based on the total amount of the silica solid content and the alkyl silicate solid content of the water glass of the inorganic reactant (if the ratio of the silica component of the water glass is too low), The amount of silicon dioxide (silica component) in the water glass bound to the silanol group of the alkyl silicate is insufficient, the hydrolysis and subsequent condensation reaction proceeds in the alkyl silicate, causing gelation, resulting in poor stability of the aqueous coating composition. Become.
Therefore, by making the silica solid content of the water glass of the inorganic reaction material within the range of 75 wt% or more and 90 wt% or less with respect to the total amount of the silica solid content of the water glass of the inorganic reaction material and the solid content of the alkyl silicate, Ensures the stability of the water-based paint composition, and ensures excellent water resistance in the coating film formed by applying this water-based paint composition. Excellent corrosion resistance and rust prevention by alkyl silicate. The ability to show off.

  And in the manufacturing method of the water-based coating composition of this invention, by preparing beforehand the inorganic reaction material which mixed water glass and the alkyl silicate in this way, water glass couple | bonds with an alkyl silicate, and it is alkyl. Gelation due to the hydrolysis of the silicate and subsequent condensation reaction is prevented, and the stability of the aqueous coating composition is ensured. For the stabilization of the aqueous coating composition, an acrylic resin and an alkyl silicate are used. Since it is not necessary to emulsify, labor (work) and cost associated with emulsification are not required. Furthermore, acrylic resin, water glass, and alkyl silicate are all materials that can be obtained at low cost. For this reason, a water-based coating composition can be manufactured at low cost.

Thus, it is a method for producing an aqueous coating composition that can be produced at low cost, has excellent stability, and can form a coating film having excellent weather resistance, corrosion resistance, and rust prevention properties.

  According to the method for producing a water-based coating composition of the invention of claim 5, the solid content of the acrylic resin is the total amount of the silica solid content of the water glass of the inorganic reaction material and the solid content of the alkyl silicate and the solid content of the acrylic resin. It is in the range of 80 wt% or more and 99 wt% or less with respect to the total weight.

  Here, if the solid content of the acrylic resin is high and exceeds the above range, the solid content of the alkyl silicate is too small, and the effect of improving the corrosion resistance and rust resistance by the alkyl silicate cannot be obtained. On the other hand, when the solid content of the acrylic resin is low and less than the above range, the silica solid content of the water glass is increased, whereby the viscosity of the aqueous coating composition is increased and the stability is lowered. Furthermore, even in the coating film formed by applying the aqueous coating composition, when the ratio of hydrophilic water glass is high, the water resistance is reduced and sufficient corrosion resistance and rust prevention due to alkyl silicate are not exhibited, The coating film performance decreases.

  Accordingly, the solid content of the acrylic resin is in the range of 80 wt% or more and 99 wt% or less with respect to the total weight of the silica solid content of the water glass of the inorganic reaction material and the solid content of the alkyl silicate and the solid content of the acrylic resin. If it is inside, in addition to the effect of Claim 4, the highly stable aqueous coating composition is obtained reliably, In the coating film formed by apply | coating this aqueous coating composition, it was excellent in water resistance Film performance such as corrosion resistance, corrosion resistance and rust prevention can be ensured.

According to the method for producing an aqueous coating composition of the invention of claim 6, since the solvent is substantially only water except for the solid content, in addition to the effect of claim 4 or 5, There is almost no risk of generating volatile organic compounds (VOC), and an environmentally friendly aqueous coating composition can be obtained. In particular, the present invention stabilizes an aqueous coating composition by mixing an alkyl silicate and water glass to prevent the water glass from binding to the alkyl silicate and preventing gelation due to hydrolysis of the alkyl silicate and subsequent condensation reaction. Since it is not necessary to emulsify the acrylic resin and the alkyl silicate for stabilization of the aqueous coating composition, an aqueous coating composition is obtained without the need for an organic solvent for emulsification. Is extremely environmentally friendly.

  Embodiments of the present invention will be described below. The aqueous coating composition according to the embodiment of the present invention has a basic composition of an acrylic resin, an inorganic reaction material prepared by mixing water glass and an alkyl silicate, and water as a solvent.

  Here, the “acrylic resin” broadly includes an acrylic resin or a methacrylic resin, and means a single polymer or copolymer of a monomer selected from an alkyl acrylate ester, an alkyl methacrylate ester, and the like. Specific examples of these monomers include methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, acrylic acid-styrene, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, and methacrylic acid. Various monomers such as isobutyl can be used. A derivative of acrylic acid or methacrylic acid, for example, a polymer such as acrylamide or acrylonitrile may be contained. And acrylic resin is not limited to 1 type, 2 or more types may be combined.

“Water glass” is an aqueous solution of alkali metal silicate (alkali silicate), and specific examples include aqueous solutions of sodium silicate (sodium silicate), potassium silicate, lithium silicate and the like. The alkali metal silicate is a compound represented by the general formula M ₂ O.nSiO ₂ (M is sodium (Na), potassium (K), lithium (Li), etc.), and M ₂ O and SiO ₂ The molar ratio of n is generally 1.6 to 4.5.

“Alkylsilicate” is an alkoxysilane oligomer starting from tetraalkoxysilane, and has a general formula of Si _n O _n-1 (OR) _{2n + 2} (Si is silicon, O is oxygen, and R is an alkyl group) ). Specifically, tetraalkoxysilanes such as tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, and tetrabutoxysilane with n = 1, and partial hydrolysates thereof with n = 2 or more, such as methyl silicate and ethyl silicate. , Propyl silicate and the like can be used. These can be used alone or in combination of two or more.

Moreover, ion-exchange water etc. are used for the water as a solvent.
In particular, in the present embodiment, the acrylic silicate and the water silicate are mixed as described later without dissolving and emulsifying (emulsion) the acrylic resin and the alkyl silicate in the organic solvent as in the prior art. By simply placing the inorganic reaction material on the acrylic resin, the water-based coating composition is prevented from hydrolysis of the alkyl silicate and subsequent condensation reaction by water glass, so that stability is ensured. For this reason, without using an organic solvent for emulsification, only water can be positively used as the solvent. Therefore, there is almost no fear of generating a volatile organic compound (VOC), and there is no need to provide a work environment such as an exhaust facility, so that the water-based coating composition is environmentally friendly.

In the aqueous coating composition of the present embodiment, the water glass and the alkyl silicate are mixed as the inorganic reaction material, and the mixing ratio is such that the silica solid content of the water glass of the inorganic reaction material is the water glass of the inorganic reaction material. The total weight (total amount) of the silica solid content and the alkyl silicate solid content is adjusted to be in the range of 75 wt% or more and 90 wt% or less.
Here, when the silica solid content of the water glass of the inorganic reaction material exceeds 90% by weight with respect to the total amount of the silica solid content and the alkyl silicate solid content of the water glass of the inorganic reaction material, the water glass contained in the inorganic reaction material The ratio of the silica component is too high, and the silica content of the water glass contained in the aqueous coating composition increases. For this reason, due to the high hydrophilicity of the silica component, the water resistance of the coating film formed by applying the aqueous coating composition tends to be insufficient. On the other hand, when the silica solid content of the water glass contained in the inorganic reaction material is less than 75% by weight, the silica ratio of the water glass in the inorganic reaction material is too small and the silica of the water glass bonded to the silanol group of the alkyl silicate. In the alkyl silicate in which the component amount is insufficient and the silica component of the water glass is not bonded, the hydrolysis and the subsequent condensation reaction proceed to gel, and the stability of the aqueous coating composition tends to deteriorate.

  Thus, the silica solid content of the water glass contained in the inorganic reaction material is within a predetermined range with respect to the total amount of the silica solid content of the water glass of the inorganic reaction material and the solid content of the alkyl silicate, and the alkyl silicate By adjusting the mixing amount (blending amount) of the silica solid content of the water glass with respect to the solid content, it becomes possible for the alkyl silicate that enhances the rust prevention property to be stably present in the aqueous coating composition. This increases the stability of the aqueous coating composition. Moreover, the deterioration of the water resistance of the water-based coating composition is prevented by setting the amount of silica added to the water glass contained in the inorganic reaction material within a predetermined range. Accordingly, the mixing ratio of the silica solid content of the water glass and the alkyl silicate solid is 75% of the silica solid content of the water glass of the inorganic reaction material relative to the total amount of silica solid content of the water glass of the inorganic reaction material and the solid content of the alkyl silicate. In the range of not less than 90% by weight and not more than 90% by weight, this can be expressed in terms of weight ratio. Silica solid content of water glass / solid content of alkyl silicate = 75/15 to 90/10. Optimum, and by making it within such a predetermined range, the stability of the aqueous coating composition can be reliably ensured, and the coating film formed by applying this aqueous coating composition is surely good It is possible to ensure excellent water resistance and to exhibit excellent corrosion resistance and rust resistance by alkyl silicate.

Further, in the water-based coating composition of the present embodiment, the silica solid content of the water glass and the solid content of the alkyl silicate are blended in an optimum ratio as described above, and the solid content of the acrylic resin is mixed with the water glass of the inorganic reaction material. It is preferable to blend so as to be in the range of 80% by weight or more and 99% by weight or less with respect to the total weight of the solid content of the silica and the total solid content of the alkyl silicate and the solid content of the acrylic resin.
If the solid content of the acrylic resin is more than 99% by weight based on the total weight of the silica solid content of the water glass of the inorganic reaction material and the solid content of the alkyl silicate and the solid content of the acrylic resin, the corrosion resistance due to the alkyl silicate It becomes difficult to obtain the effect of improving rust prevention. On the other hand, if the solid content of the acrylic resin is less than 80% by weight, the ratio of the silica solid content of the water glass in the aqueous coating composition is increased, so that the viscosity of the aqueous coating composition is likely to increase and the stability is increased. Tend to decrease. Furthermore, in the coating film formed by applying the aqueous coating composition, since the silica component of the water glass is hydrophilic, the water resistance is reduced by increasing the silica solid content ratio of the water glass, Sufficient corrosion resistance (rust resistance) due to the alkyl silicate is not exhibited, and the coating film performance tends to deteriorate.

  The solid content of the acrylic resin is in the range of 80% by weight or more and 99% by weight or less, in other words, with respect to the total weight of the silica solid content of the water glass of the inorganic reaction material and the solid content of the alkyl silicate and the solid content of the acrylic resin. For example, the total amount of silica solid content of the water glass of the inorganic reaction material and the solid content of the alkyl silicate is the total weight of the solid content of silica solid content of the water glass of the inorganic reaction material and the solid content of the alkyl silicate and the solid content of the acrylic resin. If it is in the range of 1% by weight or more and 20% by weight or less, a highly stable aqueous coating composition is surely obtained, and coating with excellent coating performance such as water resistance, corrosion resistance and rust prevention is obtained. A film can be formed. In addition, the compounding quantity of the solid content of an acrylic resin can also be represented by the ratio of the weight with respect to the total amount of the solid content of the silica solid content of the water glass of an inorganic reaction material and an alkylsilicate, In this case, the solid content of an acrylic resin ( Weight) / (silica solid content of water glass (weight) + solid content of alkyl silicate (weight)) = 80/20 to 99/1.

In the present embodiment, a mixed liquid in which alkyl silicate and water glass are adjusted to a predetermined ratio, that is, an inorganic reaction material is added to and mixed with an acrylic resin, and further water or the like as a solvent is added to the water-based paint. A composition is produced.
The aqueous coating composition according to the present embodiment thus produced is applied as a water-based coating agent on the surface of a metal substrate such as an automobile part, a home appliance, a building material, or a cast forging product, for example. Usually, it is cured by heating and drying at a predetermined temperature for a predetermined time to form a coating film. At this time, as a method for applying the aqueous coating composition to the surface of the substrate, it is applied at least once by a known method such as an air spray method, a shower method, a spray method, a roll coating method, a brush coating method, or a dipping method. Can be applied. Moreover, the dry film thickness of the coating film formed by apply | coating the water-based coating composition of this Embodiment to the base-material surface is in the range of 10 micrometers-70 micrometers, for example, Preferably it is in the range of 15 micrometers-40 micrometers. Preferably, it exists in the range of 15 micrometers-25 micrometers. If it is in this range, the coating film has sufficient adhesion to the substrate surface, and can impart sufficient water resistance, corrosion resistance and rust resistance to the substrate.

  In addition, in the water-based coating composition according to the present embodiment, acrylic resin, alkyl silicate, water glass, water as a solvent is a basic composition, but in addition to these basic composition blends, if necessary , Additives such as a catalyst, a coupling agent, an antifoaming agent and a pigment are blended.

Thus, the water-based paint composition according to the present embodiment contains an acrylic resin, an inorganic reaction material in which water glass is mixed with an alkyl silicate, water as a solvent, and the like.
Here, when the alkyl silicate is arranged on the acrylic resin, the rust prevention property is improved as compared with the case where no alkyl silicate is arranged. Usually, however, water is present in the water-based coating composition, and the presence of this water causes the alkyl silicate. Hydrolysis by the silanol groups of the silicate and subsequent condensation reaction proceed to form a gel. For this reason, there has been a problem in stability with an aqueous coating composition of an acrylic resin and an alkyl silicate without water glass.
Therefore, in the water-based coating composition of the present invention, water glass is mixed in advance at a predetermined ratio with respect to the alkyl silicate. Specifically, the total amount of silica solid content of the water glass of the inorganic reaction material and the solid content of the alkyl silicate. In contrast, the silica solid content of the water glass of the inorganic reaction material is in the range of 75 wt% or more and 90 wt% or less, or as another way of expressing, the silica solid content of the water glass with respect to the solid content of the alkyl silicate in weight ratio, Silica solid content of water glass / solid content of alkyl silicate = 75/25 to 90/10, so that silanol group of alkyl silicate (exactly, a part of alkoxy silyl group of alkyl silicate is mixed with water) The silica component of water glass is bonded to the silanol group (-SiOH) generated by hydrolysis upon contact, and alkyl Suppresses hydrolysis and subsequent condensation reaction between silanol groups of the silicate, thereby preventing gelation of the alkyl silicate, resulting in a stable inorganic reaction material in a solution state, ensuring the stability of the aqueous coating composition and storage Stability can be improved.

  When this water-based coating composition is applied to an object to be coated, the water evaporates to break the bond between the water glass and the silanol group of the alkyl silicate, and the hydrolysis and subsequent condensation of the alkyl silicate. As the reaction proceeds, the alkyl silicate cures to form a silica film, and the reaction between the alkyl silicate and the acrylic resin forms a coating that exhibits corrosion resistance and rust resistance, and is weather resistant. The excellent acrylic resin ensures the weather resistance of the coating film.

  At this time, in order to keep the alkyl silicate stable in the aqueous coating composition, the aqueous coating composition is in the form of an inorganic reaction material in which water glass and the alkyl silicate are blended so as to be within the specified range. It becomes possible by containing. By forming this stable form of the inorganic reactant in advance, the alkyl silicate is stably present in the aqueous coating composition, and in the coating film formed by applying such an aqueous coating composition, it is surely excellent in water resistance. Film properties such as corrosion resistance, corrosion resistance, and rust resistance can be obtained.

And in this Embodiment, an aqueous coating composition is stabilized only by mixing the inorganic reaction material produced from the alkyl silicate and water glass adjusted by the predetermined ratio in this way with an acrylic resin. Therefore, it is not necessary to emulsify the acrylic resin and the alkyl silicate for stabilization of the aqueous coating composition, and labor (operation) and cost associated with emulsification are not required. Furthermore, acrylic resin, water glass, and alkyl silicate are all materials that can be obtained at low cost. Therefore, an aqueous coating composition can be obtained at low cost.
[Example]

Next, examples of the aqueous coating composition according to the embodiment of the present invention will be specifically described.
As a blending composition of the aqueous coating composition according to the present embodiment, an inorganic reaction material prepared by adding water glass to an acrylic resin, an alkyl silicate, water as a solvent, etc., and water of the inorganic reaction material The water content of the water glass of the inorganic reaction material is within the range of 75% by weight or more and 90% by weight or less based on the total amount of the silica solid content of the glass and the solid content of the alkyl silicate (silica solid content of the water glass relative to the solid content of the alkyl silicate. Are water glass silica solid content / alkyl silicate solid content = within a range of 75/25 to 90/10), and water-based coating compositions of Examples 1 to 4 were prepared.

In the aqueous coating compositions according to Examples 1 to 4, an acrylic resin emulsion (“Boncoat EC-740EF” manufactured by DIC Corporation: solid content 40%, particle size) is used as an “acrylic resin” which is an aqueous resin. 70-80 μm, MFT 18 ° C.). Further, as “alkyl silicate”, methyl silicate (“Methyl silicate 51” manufactured by Colcoat Co., Ltd .: solid content (silica solid content) 50%) is used, and as “water glass”, lithium silicate (Nippon Chemical Co., Ltd.) is used. “Lithium silicate 35” manufactured by Kogyo Co., Ltd .: solid content 29% (silica solid content 20%)), an acid catalyst (0.1N acetic acid) as a catalyst (additive) and ion-exchanged water as a solvent Was used.
Here, methyl silicate as an alkyl silicate, lithium silicate as a water glass, an acid catalyst, and ion-exchanged water were mixed to obtain an inorganic reaction material. Further, ion-exchanged water is used as a solvent for the aqueous coating composition, and as an additive, a coupling agent (“KBM603” manufactured by Shin-Etsu Chemical Co., Ltd .: solid content (silica solid content) 94%), an antifoaming agent ( Sannoco Co., Ltd. “SN-DEFOAMER 381”: solid content 48%) and pigment (“NAF5091 Black” manufactured by Dainichi Seika Kogyo Co., Ltd .: pigment solid content 35%, resin solid content 5%) were used.
Here, the composition of each example is shown in the upper part of Table 1.

In Example 1, 64.8 g of the silica solid content of lithium silicate as the water glass is blended with 7.2 g of the solid content of methyl silicate as the alkyl silicate as the inorganic reaction material. The solid content of the alkyl silicate is the silica solid content of the water glass / the solid content of the alkyl silicate = 90/10 in weight ratio, and the silica solid content of the water glass of the inorganic reaction material is the water glass of the inorganic reaction material. 90% by weight based on the total amount of silica solids and alkyl silicate solids.
In Example 2, 60.0 g of the silica solid content of lithium silicate as the water glass is blended with 12.0 g of the solid content of methyl silicate as the alkyl silicate as the inorganic reactant, The solid content of the alkyl silicate is, by weight ratio, the silica solid content of the water glass / the solid content of the alkyl silicate = 83/17, and the silica solid content of the water glass of the inorganic reaction material is the water glass of the inorganic reaction material. And 83 wt% based on the total amount of silica solids and alkylsilicate solids.

In Example 3, 57.6 g of the silica solid content of lithium silicate as the water glass is blended with 14.4 g of the solid content of methyl silicate as the alkyl silicate as the inorganic reaction material. The solid content of the alkyl silicate is the silica solid content of the water glass / the solid content of the alkyl silicate = 80: 20 by weight, and the silica solid content of the water glass of the inorganic reaction material is the water glass of the inorganic reaction material. 80% by weight based on the total amount of silica solids and alkylsilicate solids.
In Example 4, 54.0 g of the silica solid content of lithium silicate as the water glass was blended with 18.0 g of the solid content of methyl silicate as the alkyl silicate as the inorganic reaction material. The solid content of the alkyl silicate is, by weight, the silica solid content of the water glass / the solid content of the alkyl silicate = 75: 25, and the silica solid content of the water glass of the inorganic reaction material is the water glass of the inorganic reaction material. 75% by weight based on the total amount of silica solids and alkyl silicate solids.

Here, the manufacturing method of the aqueous coating composition concerning Example 1 thru | or Example 4 is demonstrated. In each example, methyl silicate, which is an alkyl silicate, is first added to a predetermined container and stirred so that the solid content becomes a predetermined amount. The acid catalyst, which is 0. Add 1N acetic acid in the amount specified in Table 1 and stir. Further, after adding a predetermined amount of ion-exchanged water as a solvent contained in the inorganic reactant shown in Table 1 and stirring, the addition amount shown in Table 1 is added and stirred in order to make lithium silicate as water glass a predetermined ratio. To do. The thus produced alkyl silicate, water glass, acid catalyst, and ion-exchanged water are the inorganic reaction materials of the present invention.
Next, the inorganic reaction material prepared in advance while stirring the acrylic resin in a predetermined container, the solid content of the acrylic resin is the silica solid content of the water glass of the inorganic reaction material and the solid content of the alkyl silicate. The ratio of the acrylic resin to the total amount is 90/10 in terms of the weight ratio of the solid content of the acrylic resin to the total amount of the silica solid content of the water glass of the inorganic reaction material and the solid content of the alkyl silicate. The addition amount shown in Table 1 so that the solid content is 90% by weight based on the total weight of the silica solid content of the water glass of the inorganic reaction material and the solid content of the alkyl silicate and the solid content of the acrylic resin. Added.

Here, a coupling agent obtained by diluting a predetermined amount of the coupling agent described in Table 1 with ion-exchanged water (which is different from the solvent in the inorganic reaction material) as a predetermined amount of solvent in another container. Dilution water is added to the mixed solution of the acrylic resin and the inorganic reaction material and stirred.
Further, a pigment and an antifoaming agent are added and mixed by stirring to produce an aqueous coating composition according to Examples 1 to 4 of the present invention.
In the embodiment of the present invention, the stirring uses a disper. The stirring conditions are not particularly limited as long as they can be sufficiently mixed. For example, the rotational speed can be in the range of 100 rpm to 1000 rpm, and the stirring time can be 10 minutes to 30 minutes.

Next, in order to compare the characteristics, aqueous coating compositions in which the silica solid content of the water glass of the inorganic reaction material was outside the scope of the present invention were prepared as Comparative Examples 1 to 4. Moreover, the water-based coating composition containing the colloidal silica of the inorganic silicon compound which has a silica similar to water glass instead of water glass was produced as the comparative example 5 thru | or the comparative example 8. FIG.
The composition of Comparative Examples 1 to 4 is as shown in the upper part of Table 1 together with Examples 1 to 4. The formulations of Comparative Examples 5 to 8 are shown in the upper part of Table 2 below.

As shown in Table 1, Comparative Example 1 does not contain any alkyl silicate, and the ratio of the silica solid content of the water glass contained in the inorganic reaction material to the alkyl silicate solid content is 100 / weight ratio. 0, the silica solid content of the water glass of the inorganic reaction material is 100% by weight with respect to the total amount of the silica solid content of the water glass of the inorganic reaction material and the solid content of the alkyl silicate.
In Comparative Example 2, lithium silicate as water glass is added to methyl silicate as alkyl silicate, but the ratio of the silica solid content of water glass contained in the inorganic reaction material to the solid content of alkyl silicate in weight ratio is The silica solid content of the water glass of the inorganic reaction material is 95% by weight based on the total amount of the silica solid content of the water glass of the inorganic reaction material and the solid content of the alkyl silicate, and defines the silica addition amount of the water glass More than the range.

In Comparative Example 3, lithium silicate as water glass is added to methyl silicate as alkyl silicate as in Comparative Example 2, but the solid content of the silica silicate in the water glass contained in the inorganic reaction material is solid. The ratio is 70/30 by weight, and the silica solid content of the water glass of the inorganic reaction material is 70% by weight based on the total amount of the silica solid content of the water glass of the inorganic reaction material and the solid content of the alkyl silicate. The amount of silica added is less than the specified range.
In Comparative Example 4, water glass is not added at all, and the ratio of the silica solid content of the water glass contained in the inorganic reaction material to the solid content of the alkyl silicate is 0/100 by weight. The silica solid content of the water glass is 0% by weight based on the total amount of the silica solid content of the water glass of the inorganic reaction material and the solid content of the alkyl silicate.

In addition, as shown in Table 2, Comparative Examples 5 to 8 are colloidal silica (incorporated by Nippon Chemical Industry Co., Ltd.), an inorganic silicon compound having silica similar to water glass, instead of water glass. Silica Doll (registered trademark) 30 ”: solid content (silica solid content) 30%).
In Comparative Example 5, as in Comparative Example 1, no alkyl silicate is disposed on the inorganic reaction material. Comparative Examples 6 to 8 are the alkyl silicates of the silica solid content of colloidal silica contained in the inorganic reaction material. The ratio by weight to the solid content is within the range of 75/25 to 95/5, that is, the silica solid content of the colloidal silica of the inorganic reaction material is changed to the silica solid content of the colloidal silica of the inorganic reaction material and the solid content of the alkyl silicate. It is within the range of 75% to 95% by weight with respect to the total amount.
These Comparative Examples 1 to 8 were also produced by the same manufacturing method as in Examples 1 to 4. The same applies to Examples 5 to 9 and Comparative Examples 9 to 15 described later.

  And about the water-based coating composition of these Examples 1 thru | or Example 4 and Comparative Example 1 thru | or Comparative Example 8, the characteristic evaluation as a water-based coating was implemented. The evaluation items here were the stability of the water-based coating composition and the water resistance of the coating film.

  Regarding the stability of the aqueous coating composition, the blended materials shown in Table 1 and Table 2, that is, the aqueous resin (acrylic resin), the inorganic reaction material, the ion-exchanged water as the solvent, and various materials of the additive are mixed. A change in viscosity was judged, and the case where the viscosity did not increase (thickening) was evaluated as ◯, the case where the viscosity increased slightly (thickening) was evaluated as Δ, and the gelation was evaluated as ×.

  As for the water resistance of the coating film, each water-based coating composition of Examples and Comparative Examples was prepared such that the dry film thickness was 25 μm on the surface of the untreated cold-rolled steel sheet (SPCC-SD) as a base material. A specimen prepared by air spray coating and drying at 60 ° C. for 20 minutes was used. The specimen was immersed in warm water at 40 ° C. for 240 hours (10 days), and then subjected to a 1 mm cross-cut tape peeling test (1 mm width, 100 squares) according to JIS-K5600-5-6. In the 1 mm cross cut tape peeling test, 11 parallel cuts were made at 1 mm intervals vertically and horizontally with a cutter knife on the painted surface of the specimen to form a total of 100 1 mm × 1 mm squares. Adhesive cellophane tape is strongly pressure-bonded and attached to the cell forming portion from above, peeled off at once, and the state of the cell after peeling off is evaluated. Here, the number of peeled squares was counted, and the number of peeled squares was zero and no peeling was evaluated as 桝. When even one piece was peeled off, it was evaluated as ×.

The result of each characteristic evaluation is as shown in the lower part of Tables 1 and 2.
As shown in Table 1, the silica solid content of the water glass of the inorganic reaction material is 75/25 to 90/10 by weight ratio with respect to the solid content of the alkyl silicate, that is, the silica solid content of the water glass of the inorganic reaction material is Stability of all aqueous coating compositions of Examples 1 to 4 which are within the range of 75 wt% to 90 wt% with respect to the total amount of silica solid content of the water glass of inorganic reaction material and solid content of the alkyl silicate With respect to, the viscosity did not increase when the water-based coating composition was produced, and it did not gel, and it had adequate fluidity suitable for coating, and good results were obtained. In addition, regarding the water resistance of the coating films formed by applying the water-based coating compositions of Examples 1 to 4, all the coating film adhesive strength after being immersed in warm water for 240 hours is 1 of 100 squares. It showed excellent water resistance that the individual did not peel off.

On the other hand, in the comparative example 1 of the composition which does not mix | blend the alkyl silicate with the inorganic reaction material shown in Table 1, it becomes gel form when producing an aqueous coating composition by not containing an alkyl silicate. However, the coating film formed from this aqueous coating composition had poor water resistance.
Further, the weight ratio of the silica solid content of the water glass in the inorganic reaction material to the alkyl silicate solid content is 90/10, that is, the silica solid content of the water glass of the inorganic reaction material is the silica solid content of the water glass of the inorganic reaction material and In Comparative Example 2, which is more than 90% by weight based on the total amount of the solid content of the alkyl silicate, it did not become a gel during the preparation of the aqueous coating composition, but the coating film formed from the aqueous coating composition was water resistant. It was inferior to.

On the other hand, the weight ratio of the silica solid content of the water glass in the inorganic reaction material to the alkyl silicate solid content is 75/25, that is, the silica solid content of the water glass of the inorganic reaction material is the silica solid content of the water glass of the inorganic reaction material and In Comparative Example 3, which is less than 75% by weight based on the total amount of the solid content of the alkyl silicate, it was confirmed that the water-based coating composition was gelled and not stable and not suitable for coating. In addition, about this water-based coating composition, since it was not suitable for coating, the water resistance evaluation test was not implemented.
Moreover, in the comparative example 4 of the composition which does not mix | blend water glass with an inorganic reaction material, since the water glass is not mix | blended, the hydrolysis reaction of alkylsilicate and subsequent condensation reaction advances, and water-based coating composition preparation is carried out. It turned out to be a gel and was not stable and was not suitable for painting. In addition, since this water-based coating composition is not suitable for coating, a water resistance evaluation test was not performed.

  Here, in Comparative Examples 5 to 8 in which colloidal silica was blended in place of water glass of the inorganic reaction material shown in Table 2, the silica solid content of colloidal silica in Comparative Example 7 and Comparative Example 8 was alkyl silicate. 75/25 to 90/10 in weight ratio with respect to the solid content of the colloidal silica in the inorganic reaction material, the silica solid content of the colloidal silica of the inorganic reaction material and the total solid content of the alkyl silicate Even when blended within the range of 75 wt% or more and 90 wt% or less, the stability of the aqueous coating composition was inferior as compared with Examples 1 to 4.

That is, in Comparative Example 7, thickening was observed in the aqueous coating composition, and a slight gelation was observed compared to Examples 1 to 4, resulting in inferior stability of the aqueous coating composition. It was. Furthermore, in Comparative Example 8, it was found that the water-based coating composition was gelled during preparation and was not suitable for coating. In addition, about the comparative example 8, since it was not suitable for coating, the water resistance evaluation test was not implemented.
Further, Comparative Example 5 having a composition in which an alkyl silicate is not blended even when colloidal silica is blended in the inorganic reaction material, and the silica solid content of the colloidal silica is 90/10 by weight with respect to the solid content of the alkyl silicate, that is, inorganic In Comparative Example 6 in which the silica solid content of the colloidal silica of the reaction material exceeded 90% by weight relative to the total amount of the silica solid content of the colloidal silica of the inorganic reaction material and the solid content of the alkyl silicate, the aqueous coating composition was prepared. Although it did not become a gel, the coating film formed from the aqueous coating composition was inferior in water resistance.

  From the above results, an inorganic reaction material prepared by adding silica solid content of water glass within a predetermined range to the solid content of alkyl silicate was prepared in advance, and this was added to and mixed with an acrylic resin that is an aqueous resin. It was confirmed that the aqueous coating compositions of Examples 1 to 4 produced in this way were excellent in stability and could form a coating film having excellent water resistance without gelation during production.

In particular, from the comparison with Comparative Example 2, the silica solid content of the water glass is 90/10 by weight with respect to the solid content of the alkyl silicate, that is, the silica solid content of the water glass of the inorganic reaction material is the water of the inorganic reaction material. When it exceeds 90% by weight with respect to the total amount of silica solids and alkylsilicate solids in the glass, the ratio of silica components in the cured water glass increases in the coating film formed by applying the aqueous coating composition, The water resistance is impaired by the high hydrophilicity of the silica component.
On the other hand, from the comparison with Comparative Example 3, the silica solid content of the water glass is 75/25 by weight with respect to the solid content of the alkyl silicate, that is, the silica solid content of the water glass of the inorganic reaction material is When the total amount of silica solids of water glass and alkyl silicate is less than 75% by weight, the amount of silica component of water glass that binds to silanol groups of alkyl silicate is insufficient, and is bound by the silica component of water glass. The alkyl silicate which has not been gelled by hydrolysis and the subsequent condensation reaction deteriorates the stability of the paint.
From these results, the silica solid content of the water glass of the inorganic reaction material is 75/25 or more and 90/10 or less with respect to the alkyl silicate solid content, that is, the silica solid content of the water glass of the inorganic reaction material and the alkyl silicate. The blending is preferably within the range of 75% by weight or more and 90% by weight or less with respect to the total amount of the solid content, and by making an aqueous coating composition of such a blending, it is surely a coating having excellent stability, Excellent water resistance can be secured in the coating film to be formed.

Moreover, it turns out that it becomes a coating composition excellent in stability by using water glass instead of colloidal silica even if it is an inorganic silicon compound from the comparison with Comparative Example 5 thru | or Comparative Example 8.
Here, colloidal silica does not become a stable coating composition because the silica component of colloidal silica is more stable than the silica component of water glass, and binds to silanol groups of alkyl silicate like water glass. This is considered to be because the force is weak and it is difficult to suppress gelation due to hydrolysis of the alkyl silicate and subsequent condensation reaction.

  Incidentally, water glass is cheaper than colloidal silica, and acrylic resin is also cheaper than epoxy-modified resins used in conventional anticorrosive paints. For this reason, a water-based coating composition can be manufactured at low cost.

  By the way, in the said Example 1 thru | or Example 4 and Comparative Example 1 thru | or Comparative Example 4, although what used the lithium silicate as water glass and used the methyl silicate as the alkyl silicate was shown, According to experimental studies, sodium silicate (sodium silicate) or potassium silicate is used as the water glass, ethyl silicate is used as the alkyl silicate, and the silica solid content of the above examples and water glass is the same. Then, each water-based coating composition was prepared, and the characteristics were evaluated in the same manner as described above. As a result, it was confirmed that the same results as in the above examples were obtained.

In addition, since lithium silicate is excellent in adhesiveness, according to the aqueous coating composition containing water glass formed with an aqueous solution of lithium silicate, it improves the strength when applied to the surface to be coated to form a coating film, In addition, adhesion to the painted surface can be improved. Water glass formed with an aqueous solution of sodium silicate or potassium silicate is inexpensive and heat resistant.

As described above, by adding water glass to the alkyl silicate in advance and preparing an inorganic reaction material in which the silica solid content of the water glass relative to the solid content of the alkyl silicate is adjusted within a specified range, silanol groups of the alkyl silicate are produced. It suppresses that a hydrolysis and subsequent condensation reaction by mutual progress and gelatinize. And the stability of an aqueous coating composition is ensured by mixing the inorganic reaction material which stabilized the alkyl silicate with water glass with an acrylic resin.
When this water-based paint composition is applied to an object to be coated, the water evaporates, so that the suppression of gelation of the alkyl silicate by water glass is solved, and the reaction between the alkyl silicate and the acrylic resin results in corrosion resistance and rust prevention. A coating film exhibiting properties is formed. Here, the weather resistance of a coating film is ensured by the acrylic resin excellent in weather resistance.
At this time, since it is not necessary to emulsify the acrylic resin and the alkyl silicate for stabilizing the aqueous coating composition, labor (work) and cost associated with emulsification are not required. Furthermore, water glass is a material that can be obtained at low cost. For this reason, an aqueous coating composition can be obtained at low cost.

In this way, the aqueous coating composition can be produced at low cost, and can form a coating film having excellent stability and excellent weather resistance, corrosion resistance and rust resistance.

  Here, in order to obtain a coating film that exhibits excellent coating performance such as stability, the solid content of the acrylic resin is determined with respect to the ratio of the addition amount of the acrylic resin and the inorganic reactant, which is the main composition of the aqueous coating composition. From the water-based coating compositions of Examples 5 to 9 defined by the ratio of the inorganic reaction material to the total amount of silica solids and alkylsilicate solids in water glass, and Comparative Examples 9 and 10 outside the specified range A coating was prepared and evaluated. The composition of each Example and Comparative Example is shown in the upper part of Table 3. Here, the same materials as in Examples 1 to 4 and Comparative Examples 1 to 4 in Table 1 above, ie, lithium silicate as water glass and methyl silicate as alkyl silicate are used, and inorganic reaction materials are used. The weight ratio of the silica solid content of the water glass to the alkyl silicate solid content is 83/17, that is, the silica solid content of the water glass of the inorganic reaction material, the silica solid content of the water glass of the inorganic reaction material and the solid content of the alkyl silicate. The proportion of the total amount of water was 83% by weight.

  As shown in Table 3, in Example 5, the solid content of the acrylic resin emulsion was 38.80 g, the lithium silicate as the water glass in the inorganic reaction material was 0.325 g of silica solid content and methyl as the alkyl silicate. A total of 0.39 g of silicate is blended with a solid content of 0.065 g. For this reason, the solid content of the acrylic resin is 99/1 in weight ratio to the total amount of silica solid content of the water glass of the inorganic reaction material and the solid content of the alkyl silicate, and the silica solid content of the water glass of the inorganic reaction material and the alkyl silicate. It becomes 99 weight% with respect to the total weight of the total amount of solid content of this, and the solid content of an acrylic resin.

In Example 6, with respect to the solid content of 34.48 g of the acrylic resin emulsion, 1.510 g of silica silicate as water glass in the inorganic reaction material and 1.510 g of methyl silicate as alkyl silicate in a solid content of 0. 309g is mixed to make a total of 1.82g. Therefore, the solid content of the acrylic resin is 95/5 by weight with respect to the total amount of the silica solid content of the water glass of the inorganic reaction material and the solid content of the alkyl silicate, and the silica solid content of the water glass of the inorganic reaction material and the alkyl silicate. It becomes 95 weight% with respect to the total weight of the total amount of solid content of this, and the solid content of an acrylic resin.
In Example 7, the solid content of acrylic resin emulsion was 29.92 g, lithium silicate as water glass in the inorganic reaction material was 2.764 g in silica solid content, and methyl silicate as alkyl silicate was in solid content in a solid content of 0.004. 566g is blended to make a total of 3.33g. For this reason, the solid content of the acrylic resin is 90/10 in weight ratio with respect to the total amount of the silica solid content of the water glass of the inorganic reaction material and the solid content of the alkyl silicate, and the silica solid content and the alkyl silicate of the water glass of the inorganic reaction material. It becomes 90 weight% with respect to the total weight of the total amount of solid content of this, and the solid content of an acrylic resin.

In Example 8, the solid content of acrylic resin emulsion is 26.04 g, lithium silicate as water glass in the inorganic reaction material is 3.810 g in silica solid content, and methyl silicate as alkyl silicate is in solid content in a solid content of 0.08. 780g is blended to make a total of 4.59g. For this reason, the solid content of the acrylic resin is 85/15 in a weight ratio with respect to the total amount of the silica solid content of the water glass of the inorganic reaction material and the solid content of the alkyl silicate, and the silica solid content and the alkyl silicate of the water glass of the inorganic reaction material. It becomes 85 weight% with respect to the total weight of the total amount of solid content of this, and the solid content of an acrylic resin.
In Example 9, with respect to the solid content of 22.76 g of the acrylic resin emulsion, lithium silicate as water glass in the inorganic reaction material was 4.722 g in silica solid content and methyl silicate as alkyl silicate was in the solid content of 0.072 g. 967g is blended to make a total of 5.69g. Therefore, the solid content of the acrylic resin is 80/20 in weight ratio with respect to the total amount of silica solid content of the water glass of the inorganic reaction material and the solid content of the alkyl silicate, and the silica solid content of the water glass of the inorganic reaction material and the alkyl silicate. 80% by weight based on the total weight of the total solid content and the solid content of the acrylic resin.

On the other hand, in Comparative Example 9, water glass and alkyl silicate were not added at all, that is, an inorganic reaction material was not disposed. However, when expressed as a ratio of water glass and alkyl silicate, the solid content of the acrylic resin was The weight ratio is 100/0 with respect to the total amount of solids of water glass and alkyl silicate, and is 100% with respect to the total weight of the total amount of silica solids and alkyl silicates in water glass and the solid content of acrylic resin. %.
In Comparative Example 10, the solid content of acrylic resin emulsion was 19.88 g, lithium silicate as water glass in the inorganic reaction material was 5.528 g in silica solid content and 1.132 g of methyl silicate as alkyl silicate. The total amount is 6.66 g. For this reason, the solid content of the acrylic resin is 75/25 by weight with respect to the total amount of silica solid content of the water glass of the inorganic reaction material and the solid content of the alkyl silicate, and the silica solid content of the water glass of the inorganic reaction material and the alkyl silicate. The total solid content and the solid content of the acrylic resin are 75% by weight.

Furthermore, in order to compare the characteristics, the inorganic reaction material is not mixed with alkyl silicate and only water glass is used. As Comparative Example 11, the water glass is lithium silicate (“Lithium silicate 35” manufactured by Nippon Chemical Industry Co., Ltd.): An aqueous coating composition containing a solid content of 29% (silica solid content: 20%), as Comparative Example 12, sodium silicate as water glass ("J. Sodium silicate No. 3" manufactured by Nippon Chemical Industry Co., Ltd.): Solid content 39% (silica solid content 29%)), as Comparative Example 13, as water glass, potassium silicate ("Betolin P35" manufactured by Wollner Silikat: solid content 23% (silica solid content 20%)) A water-based paint composition is used, and water is not added to the inorganic reaction material, and only the alkyl silicate is used. Silicate aqueous coating composition as Comparative Example 14 formulated with, as Comparative Example 15 An aqueous coating composition containing the epoxy-modified resin which corresponds to the conventional anti-rust paint instead of the acrylic resin, were each prepared.
The composition of Comparative Examples 11 to 15 is shown in the upper part of Table 4.

  The paint preparation methods of the respective aqueous paint compositions of Examples 5 to 9 and Comparative Examples 9 to 15 are the same as those of Examples 1 to 4.

And about these water-based coating compositions of these Examples 5 thru | or Example 9 and the comparative examples 9 thru | or Comparative Example 15, the characteristic evaluation as a water-based coating was implemented. The evaluation items were the stability of the water-based coating composition, the water resistance / corrosion resistance (rust resistance), adhesion, hardness, and whitening resistance of the coating film.
In the evaluation of the coating film performance, each water-based coating composition of Examples and Comparative Examples so that the dry film thickness is 25 μm on the surface of the untreated cold-rolled steel sheet (SPCC-SD) as a base material. A specimen prepared by air spray coating and drying at 60 ° C. for 20 minutes was used.
Moreover, the same evaluation method as the said Example 1 thru | or Example 4 was performed about the stability of water-based coating composition, and the water resistance of a coating film.

Two types of evaluation tests were conducted on the corrosion resistance and rust resistance of the coating film.
(Corrosion resistance / rust prevention test 1: coating film peeling test)
A cross-cut reaching the base material with a cutter knife is placed on the painted surface of the specimen, and the specimen is placed in a salt spray test (SST) device in which salt water mist is generated. Place under room temperature 35 ± 1 ° C., relative humidity 95-98% in test room, humidifier temperature 47 ± 1 ° C., salt water concentration 5 w / v%, etc.) and take out after 120 hours (5 days), The adhesive cellophane tape was strongly pressure-bonded and applied from above the crosscut, peeled off at once, the maximum peel width on one side from each crosscut after peeling was measured, and evaluated in 5 stages of 1-5.
Evaluation "5" ··· The maximum peel width from the crosscut is less than 1 mm. Evaluation "4" · · The maximum peel width from the crosscut is 1 mm or more and less than 2 mm. Evaluation "3" · · The maximum peel width from the crosscut is 2 mm. Above, less than 3 mm Evaluation “2” ・ ・ Maximum peeling width from cross cut is 3 mm or more Evaluation “1”

(Corrosion resistance / rust prevention test 2: Rust generation test)
A cross-cut reaching the base material with a cutter knife is placed on the painted surface of the specimen, and the specimen is placed in a salt spray test (SST) in which salt water mist is generated, and the salt spray conditions (test) according to JIS-Z2371 Place under room temperature 35 ± 1 ° C., relative humidity 95-98% in test room, humidifier temperature 47 ± 1 ° C., salt water concentration 5 w / v%, etc.) and take out after 120 hours (5 days), The maximum rust width (single rust width) on one side from each cross cut was measured and evaluated in five stages of 1 to 5.
Evaluation "5" ··· The rust width from the cross cut is less than 1mm. Evaluation "4" · · The rust width from the cross cut is 1mm or more and less than 2mm. Evaluation "3" · · The rust width from the cross cut is 2mm. Above, less than 3 mm Evaluation “2” ・ ・ One piece rust width from cross cut is 3 mm or more Evaluation “1”

  About the adhesiveness of the coating film, according to JIS-K5600-5-6, the 1 mm cross-cut tape peeling test (1 mm width, 100 squares) was done with respect to the coating film of a specimen. In this 1 mm cross cut tape peeling test, a total of 100 1 mm × 1 mm grids were formed by making 11 parallel cuts at 1 mm intervals in the vertical and horizontal directions with a cutter knife on the painted surface of the specimen. An adhesive cellophane tape is strongly pressure-bonded and attached from above to the cell forming portion, peeled off at once, and the state of the cell after peeling off is evaluated. Here, the number of peeled squares was counted, and the number of peeled squares was zero and no peeling was evaluated as 桝. When even one piece was peeled off, it was evaluated as ×.

About the hardness of the coating film, the maximum hardness (pencil hardness) of the pencil which does not cause peeling of the coating film surface was measured using a so-called pencil hardness measuring device according to JIS-K5600-5-4.
About the whitening resistance of a coating film, after immersing for 240 hours (10 days) in warm water of 40 degreeC, the external appearance was observed, what was not whitened was evaluated as (circle), and what was whitened was evaluated as x.

The result of each characteristic evaluation is as shown in the lower part of Tables 3 and 4.
As shown in the lower part of Table 3, the weight ratio of the solid content of the acrylic resin to the total amount of silica solid content of the water glass and the solid content of the alkyl silicate in the inorganic reaction material is within the range of 80/20 or more and 99/1 or less. That is, the solid content of the acrylic resin is 80 wt% or more and 99 wt% or less based on the total weight of the silica solid content of the water glass of the inorganic reaction material and the solid content of the alkyl silicate and the solid content of the acrylic resin. In the aqueous coating compositions of Examples 5 to 9, which are within the range, the stability of the aqueous coating composition and the water resistance, corrosion resistance (rust prevention), adhesion, hardness, and whitening resistance of the coating film. Good results were obtained in all the evaluation tests.
That is, regarding the stability of the aqueous coating composition, it was confirmed that in all of Examples 5 to 9, the aqueous coating composition was excellent in stability without gelation and increase in viscosity when the aqueous coating composition was prepared. It was.
Also, regarding the water resistance of the coating film, in all of Examples 5 to 9, excellent water resistance that the coating film adhesion after being immersed in warm water for 240 hours does not peel off one of the 100 squares. showed that.

Regarding the corrosion resistance and rust resistance of the coating film, in the coating film peeling test (corrosion resistance and rust resistance 1), in all of Examples 5 to 9, peeling after 120 hours (5 days) of salt spray condition Good results with a width of less than 3 mm and an evaluation of “3” or more were obtained. In particular, in Example 6, the peeling width is 1 mm or more and less than 2 mm in the evaluation “4”, and in Examples 7 and 8, the peeling width is less than 1 mm in the evaluation “5”. It has been shown.
Also, in the rust generation test (corrosion resistance / rust resistance 2), all of Examples 5 to 9 have a rust width of less than 3 mm after 120 hours (5 days) of salt spray condition, and the evaluation is “ Good results of 3 "or more were obtained. In particular, in Examples 5 to 8, the evaluation “4” showed excellent corrosion resistance and rust resistance with a rust width of 1 mm or more and less than 2 mm.

About the adhesiveness of the coating film, in all of Example 5 thru | or Example 9, the outstanding adhesiveness that 1 of 100 squares did not peel in the cross cut tape peeling test was shown.
Regarding the hardness of the coating film, the pencil hardness in the pencil hardness measurement test is F in Examples 5 and 6, and the pencil hardness in the pencil hardness measurement test is H in Examples 7 to 9, and the aqueous coating composition. It was found that the coating film formed by coating had sufficient hardness.
Regarding the whitening resistance of the coating film, in all of Examples 5 to 9, no whitening was observed after being immersed in warm water at 40 ° C. for 240 hours (10 days), and it was confirmed that the whitening resistance was also excellent. It was done.

  On the other hand, in Comparative Example 9 having a composition that does not contain an inorganic reactant shown in Table 3, it does not form an alkyl silicate, so that it becomes a gel when producing an aqueous coating composition. However, good results were obtained for the water resistance, adhesion, hardness, and whitening resistance of the coating film, but the coating film peeling test (corrosion resistance / rust resistance 1) ), The entire surface was peeled off after 120 hours (5 days) of the salt spray condition. That is, it was confirmed that when an acrylic resin was used without blending an alkyl silicate as the aqueous coating composition, it was not possible to ensure the corrosion resistance and rust prevention required for the coating film of the surface coating.

  In Comparative Example 10, the weight ratio of the solid content of the acrylic resin to the total amount of the solid content of the silica water and the alkyl silicate in the water glass of the inorganic reaction material is 75/25 less than 80/20, that is, the acrylic resin The solid content is a composition that is less than 80% by weight and 75% by weight with respect to the total weight of the silica solid content of the water glass of the inorganic reaction material and the solid content of the alkyl silicate and the solid content of the acrylic resin. In Comparative Example 10, good results were obtained with respect to the adhesion, hardness, and whitening resistance of the coating film, but the solid content of the alkyl silicate relative to the solid content of the acrylic resin, which is the main composition of the aqueous coating composition. By increasing the ratio, the viscosity increased during the preparation of the aqueous coating composition, resulting in poor coating stability compared to Examples 5 to 9. Furthermore, in the coating film formed by applying the aqueous coating composition, the ratio of the silica component by the water glass is increased, so that the water resistance is impaired due to the high hydrophilicity of the silica component by the water glass. Corrosion resistance and rust prevention due to silicate were not sufficiently exhibited, and the results were inferior in water resistance, corrosion resistance and rust prevention compared to Examples 5 to 9.

In Comparative Examples 11 to 13 of the composition not containing the alkyl silicate shown in Table 4, the coating composition does not gel because the alkyl silicate is not added. Although good results were obtained with respect to hardness and whitening resistance, they did not have the corrosion resistance and rust resistance required for the coating film of the surface coating. Furthermore, water resistance was inferior due to the high hydrophilicity of the silica component of water glass.
On the other hand, in the comparative example 14 of the composition which mix | blended the methyl silicate as an alkyl silicate with respect to an acrylic resin, but the composition which does not mix | blend water glass, hydrolysis of an alkyl silicate and subsequent after that water glass is not mix | blended. It was confirmed that the condensation reaction progressed and became a gel when the aqueous coating composition was produced, which was not suitable for coating.
Moreover, in Comparative Example 15 having a composition containing an epoxy-modified resin corresponding to a conventional rust preventive paint, good results were obtained with respect to the stability of the paint and the corrosion resistance / rust preventiveness, adhesion, and hardness of the coating film. However, it was confirmed that the whitening resistance was inferior to that of Examples 5 to 9.

  Thus, the weight ratio of the solid content of the acrylic resin to the total amount of the silica solid content of the water glass of the inorganic reaction material and the solid content of the alkyl silicate within the range of the formulation shown in Example 5 to Example 9 of Table 3 Is within the range of 80/20 or more and 99/1 or less, that is, the solid content of the acrylic resin is the sum of the solid content of the silica solid content of the water glass of the inorganic reaction material and the solid content of the alkyl silicate and the solid content of the acrylic resin. If it is in the range of 80% by weight or more and 99% by weight or less with respect to the weight, the hydrolysis of the alkyl silicate and the subsequent condensation reaction are prevented by the water glass, and the gelation is surely suppressed, and the blending of the water glass It has been found that there is no increase in viscosity due to a high rate, and the stability of the aqueous coating composition is excellent.

  Further, as can be seen from the comparison with Comparative Example 10, when the ratio of the total amount of silica solid content of the water glass of the inorganic reaction material and the solid content of alkyl silicate is high with respect to the solid content of the acrylic resin, water resistance and corrosion resistance Although the rust prevention property is lowered, the weight ratio of the solid content of the acrylic resin to the total amount of the silica solid content of the water glass of the inorganic reaction material and the solid content of the alkyl silicate is 80/20 or more, 99/1 or less, that is, acrylic The solid content of the resin is within the specified range of 80 wt% or more and 99 wt% or less based on the total weight of the solid content of the silica solid content of the water glass of the inorganic reactant and the alkyl silicate and the solid content of the acrylic resin. In the water-based paint compositions of Examples 5 to 9, the coating film having excellent coating performance with excellent corrosion resistance, rust resistance and water resistance in addition to adhesion, hardness, and weather resistance is ensured. Gain It is found.

  In particular, as shown in the aqueous coating compositions of Examples 6 to 8 in Table 3, the solid content of the acrylic resin is based on the total amount of the silica solid content of the water glass of the inorganic reactant and the solid content of the alkyl silicate. 85/15 or more and 95/5 or less in weight ratio, that is, 85 wt.% With respect to the total weight of the silica solid content of the water glass of the inorganic reaction material and the solid content of the alkyl silicate and the solid content of the acrylic resin. % Or more and 95% by weight or less, it is possible to form a coating film with more excellent corrosion resistance and rust resistance, and corrosion resistance and rust resistance comparable to conventional epoxy-modified resin-based paints. Can be secured.

  In addition, even if it arrange | positions only water glass without providing alkyl silicate to an acrylic resin from the comparative example 9 of Table 3, and the comparative examples 11 thru | or Comparative Example 13 of Table 4, it needs corrosion resistance and rust prevention property required for a coating film. By providing alkyl silicate on the acrylic resin, excellent corrosion resistance and rust resistance are secured, and from Comparative Example 15 in Table 4, the whitening resistance superior to the epoxy resin by using the acrylic resin It can be seen that can be secured. And it is confirmed again from the comparison with the comparative example 14 of Table 4 that it mix | blends water glass, hydrolysis of the alkyl silicate and subsequent condensation reaction are inhibited, gelatinization is suppressed, and it becomes a stable coating material. It was done.

  As described above, the inorganic reaction material in which the alkyl silicate and water glass are mixed, the silica solid content of the water glass in the inorganic reaction material is within the specified range with respect to the solid content of the alkyl silicate in the inorganic reaction material, Specifically, by preparing the silica solid content of the water glass in the inorganic reaction material in advance within a specified range with respect to the total amount of silica solid content of the water glass and the alkyl silicate in the inorganic reaction material, Even if an alkyl silicate is mixed with an acrylic resin, the aqueous coating composition can be stabilized without gelation. And this inorganic reaction material and acrylic resin, the solid content of the acrylic resin is within the range specified by the weight ratio with respect to the total amount of silica solid content of the water glass of the inorganic reaction material and the solid content of the alkyl silicate. Stable and stable by mixing so that the solid content is within the specified range with respect to the total weight of the silica solid content of the water glass of inorganic reaction material and the solid content of the alkyl silicate and the solid content of the acrylic resin. A highly water-based coating composition is obtained, and a coating film obtained from the aqueous coating composition is a coating film having excellent coating performance such as water resistance, corrosion resistance and rust prevention.

  In practicing the present invention, other configurations, components, materials, blending, shapes, sizes, manufacturing methods, and the like of the water-based coating composition are not limited to the present embodiment. In addition, all the numerical values raised in the embodiment of the present invention do not indicate critical values, and certain numerical values indicate appropriate values suitable for implementation. It does not deny implementation.

Claims (6)

An aqueous coating composition containing an acrylic resin, an inorganic reaction material prepared by mixing water glass and an alkyl silicate, and water as a solvent,
The silica solid content of the water glass in the inorganic reaction material is within the range of 75 wt% or more and 90 wt% or less with respect to the total amount of the silica solid content of the water glass and the solid content of the alkyl silicate of the inorganic reaction material. A water-based paint composition characterized by being.   The solid content of the acrylic resin is 80% by weight or more and 99% by weight based on the total weight of the solid content of the silica solid content of the water glass and the alkyl silicate of the inorganic reaction material and the solid content of the acrylic resin. The aqueous coating composition according to claim 1, wherein the aqueous coating composition is within the following range.   The water-based coating composition according to claim 1 or 2, wherein the solvent is substantially only water except for a solid content. A method for producing an aqueous coating composition comprising an acrylic resin, an inorganic reaction material prepared by mixing water glass and an alkyl silicate, and water as a solvent,
In the inorganic reaction material, the silica solid content of the water glass in the inorganic reaction material is 75 wt% or more based on the total amount of silica solid content of the water glass and the solid content of the alkyl silicate in the inorganic reaction material, A method for producing a water-based coating composition, which is prepared in advance by adjusting and mixing so as to be within a range of 90% by weight or less, and then mixing the inorganic reaction material with the acrylic resin.   The solid content of the acrylic resin is 80% by weight or more and 99% by weight based on the total weight of the solid content of the silica solid content of the water glass and the alkyl silicate of the inorganic reaction material and the solid content of the acrylic resin. The method for producing a water-based coating composition according to claim 4, wherein the method falls within the following range.   The method for producing an aqueous coating composition according to claim 4 or 5, wherein the solvent is substantially only water except for a solid content.