JP5340020B2 - Water-based coating agent - Google Patents

Description

  The present invention relates to an aqueous coating agent capable of improving the corrosion resistance (rust resistance) of a metal surface such as zinc-based plated steel, and more particularly to an aqueous coating agent containing colloidal silica and a styrene-butadiene copolymer emulsion. It is. “Zinc-based plated steel” refers to galvanized steel and zinc alloy plated steel.

  Here, “emulsion” (also called emulsion) is also called an emulsion, in which liquid particles form a milky state (dispersed system) as colloidal particles or coarser particles. Although it is meaningful (Saburo Nagakura et al., “Iwanami Rikagaku Dictionary (5th edition)” page 152, published by Iwanami Shoten Co., Ltd. on February 20, 1998), in this specification, claims and abstract, The term “emulsion” is used as “in which solid or liquid particles are dispersed in a liquid” that is generally used in a broad sense.

  Paints that use the sacrificial anticorrosive action of zinc against iron are widely used as zinc-rich paints, but are mainly those that use organic solvents, and contain organic solvents as volatile organic compounds (VOCs). It has a problem of adverse effects. On the other hand, water-based zinc-rich paints that do not use organic solvents have been developed in recent years, but there are problems of generation of hydrogen gas due to mixing of zinc and water and problems of poor rust prevention performance.

  Therefore, Patent Document 1 discloses an invention of a corrosion-preventing coating composition containing a water-based paint liquid, zinc dust, and a water-based aluminum pigment. Thereby, it is said that a corrosion-preventing coating composition capable of forming a coating film excellent in rust-proofing property particularly on zinc alloy-plated steel is obtained.

JP 2002-53769 A

  However, the technique described in Patent Document 1 still has a problem that the rust prevention performance is still insufficient, and the production cost increases because a large amount of zinc powder and aqueous aluminum pigment are used. It was. In addition, when a large temperature change is repeated, the coating film obtained by applying the corrosion prevention coating composition to the base material needs to expand and contract following the expansion and contraction caused by the temperature change of the base material. However, the technique described in Patent Document 1 has a problem that such stretchability cannot be imparted to the coating film.

  Therefore, the present invention has been made to solve such problems, and can improve the rust prevention properties of metals such as zinc-based plated steel, and has excellent film forming properties and is manufactured at low cost. It is an object of the present invention to provide an aqueous coating agent that is environmentally friendly and can impart stretchability to a coating film that can follow expansion and contraction caused by a temperature change of a substrate.

  The aqueous coating agent according to the invention of claim 1 is an aqueous coating agent containing colloidal silica and a styrene-butadiene copolymer (SBR) emulsion, wherein the solid content weight ratio of the colloidal silica and the SBR emulsion is: 10/90 <colloidal silica / SBR emulsion <70/30, more preferably 20/80 ≦ colloidal silica / SBR emulsion ≦ 60/40, and the solvent excluding solid content is substantially water only. It is what is.

  Here, as the “colloidal silica”, silica particles synthesized by a sol method are used as dispersoids, and silica particles having an average primary particle size of 10 nm to 50 nm are preferable, and the surface is made cationic. Cationic colloidal silica having a modified silica particle as a dispersoid is preferable from the viewpoint of stability. Note that the average primary particle diameter means that the diameter of a circle equal to the projected area of each of 100 particles existing within a certain area is obtained by observing particles dispersed to such an extent that primary particles can be discriminated. This is the average of the diameters.

  As such colloidal silica, Silica Doll (registered trademark) manufactured by Nippon Chemical Industry Co., Ltd., Adelite (registered trademark) AT manufactured by ADEKA Co., Ltd., Cataloid (registered trademark) manufactured by Catalyst Chemical Industries, Ltd., Examples include Snowtex (registered trademark) manufactured by Nissan Chemical Industries, Ltd.

  In addition, “the solvent is substantially only water” means that only water is used as the solvent for the aqueous coating agent, and no organic solvent is actively used as the solvent for the aqueous coating agent. It does not necessarily mean that no organic solvent is contained in the aqueous coating agent. For example, when the additive contains an organic solvent as an internal solvent, the aqueous coating agent inevitably contains a small amount of organic solvent, and a small amount of organic solvent is required to control the surface tension and evaporation rate. Although it may be added, it does not mean 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.

  Furthermore, a silane coupling agent is contained within the range of 0.1 to 5 parts by weight with respect to 100 parts by weight of the solid content of the colloidal silica and the SBR emulsion. Here, the “silane coupling agent” is an organosilicon compound that has both an organic functional group and a hydrolyzable group in one molecule and has a function of firmly binding an organic synthetic resin and the like to an inorganic surface. .

  Here, the coating film of the aqueous coating agent is a coating film containing the colloidal silica and the styrene-butadiene copolymer (SBR), and a silane coupling agent is interposed between the colloidal silica and the SBR. The intervening silane coupling agent imparts stretchability to the coating film.

  The aqueous coating agent according to the invention of claim 2 is the structure of claim 1, wherein the silane coupling agent has an amino group or an epoxy group at its terminal.

  Examples of such silane coupling agents include KBM-403 (3-glycidoxypropyltrimethoxysilane) and KBM-603 (N-2 (aminoethyl) -3-aminopropyl manufactured by Shin-Etsu Chemical Co., Ltd.). Trimethoxysilane), KBE-603 (N-2 (aminoethyl) -3-aminopropyltriethoxysilane), KBM-602 (N-2 (aminoethyl) -3-aminopropylmethyldimethoxysilane), etc. -Z-6610 (3-aminopropyltrimethoxysilane), Z-6011 (3-aminopropyltriethoxysilane), Z-6094 (3- (2-aminoethyl) aminopropyltrimethoxy) manufactured by Dow Corning Silane), Z-6883 (3-phenylaminopropyltrimethoxysilane), Z-6040 (3 Glycidoxypropyltrimethoxysilane), there is a Z-6042 (3- glycidoxypropylmethyldiethoxysilane), and the like.

  An aqueous coating agent according to a third aspect of the present invention is the structure according to the first or second aspect, wherein the silane coupling agent is formed from the colloidal silica particles and the styrene-butadiene copolymer (SBR) emulsion molecules. The coating film is formed on the surface of the galvanized steel. Here, as described above, the “zinc-based plated steel” refers to galvanized steel and zinc alloy plated steel.

  In the invention according to claim 1, since the water-based coating agent contains colloidal silica and SBR emulsion, the colloidal silica having excellent adhesion to a metal such as zinc can prevent rust prevention of a metal such as zinc-based plated steel. It can be improved, and good film formability can be obtained by the SBR emulsion that forms a flexible cured product with good compatibility with colloidal silica. And since a solvent is substantially only water, there is almost no possibility of generating a volatile organic compound (VOC), and it becomes an environmentally friendly aqueous coating agent.

  Here, when the solid weight ratio of the colloidal silica and the SBR emulsion is 10/90 or less (when the ratio of the SBR emulsion is too high), the rust prevention property of the formed coating film is lowered and the hardness of the coating film is also reduced. When the solid content weight ratio is 70/30 or more (when the colloidal silica ratio is too high), cracks are generated on the surface of the coating film to be formed, and the film formability is lowered. Therefore, the solid content weight ratio of the colloidal silica and the SBR emulsion is preferably in the range of 10/90 <colloidal silica / SBR emulsion <70/30.

  Further, when the solid content weight ratio of the colloidal silica and the SBR emulsion is within the range of 20/80 ≦ colloidal silica / SBR emulsion ≦ 60/40, the aqueous solution has more surely excellent rust prevention and film forming properties. Since a coating agent is obtained, it is more preferable.

  In this way, it is possible to improve the rust prevention properties of metals such as galvanized steel, have excellent film forming properties, can be manufactured at low cost, and become an environmentally friendly aqueous coating agent. .

  In addition, since the aqueous coating agent further contains a silane coupling agent in the range of 0.1 to 5 parts by weight with respect to 100 parts by weight of the solid content of the colloidal silica and the SBR emulsion, the silane The strength of the coating film and the adhesion to the metal with respect to repeated rapid temperature changes are further enhanced by the reinforcing effect and the elasticity imparting effect due to the crosslinking of the coupling agent. Accordingly, the aqueous coating agent can form a coating film that is more resistant to temperature changes.

  That is, the coating film formed from the colloidal silica particles and the SBR molecules is caused by repeated rapid temperature changes due to the silane coupling agent interposed between the colloidal silica particles and the SBR molecules in the SBR emulsion. It is possible to expand and contract following the expansion and contraction of metal. In this way, it is possible to improve the rust prevention properties of metals such as galvanized steel, have excellent film formability, can be manufactured at low cost, are environmentally friendly, and are a base material. It becomes the water-based coating agent which can provide the coating film with elasticity capable of following expansion and contraction caused by the temperature change.

  Then, the hydroxyl (—OH) group of the colloidal silica particles is bonded to the metal surface, and further, the SBR molecules are bonded through the silane coupling agent molecules to form a coating film, so that the metal is changed by a rapid temperature change. Since there is a silane coupling agent molecule between the silica particles that move together with the metal surface and the SBR molecule when it expands and contracts, the coating film is prevented from cracking due to the elasticity of the silane coupling agent molecule. In this way, the silane coupling agent molecules impart elasticity to the coating film, allowing the coating film to expand and contract following the expansion and contraction of the metal caused by repeated rapid temperature changes. To do.

  In this way, it is possible to improve the rust prevention properties of metals such as galvanized steel, have excellent film formability, can be manufactured at low cost, are environmentally friendly, and are a base material. It becomes a coating film having stretchability that can follow expansion and contraction caused by temperature change.

  In the invention according to claim 2, since the terminal of the silane coupling agent is an amino group or an epoxy group, in addition to the effect of the invention according to claim 1, a coating film that can be formed at a lower cost and Become.

  In the invention according to claim 3, since the coating film is formed on the surface of the zinc-based plated steel, the coating film in which the silane coupling agent molecule is interposed between the colloidal silica particles and the SBR molecule is the zinc-based plating. Since the adhesiveness to the steel surface is excellent, in addition to the effect of the invention according to claim 1 or claim 2, the film is more excellent in film formability and adhesiveness.

  Hereinafter, the aqueous coating agent and coating film which concern on embodiment of this invention are demonstrated. The aqueous coating agent according to the present embodiment contains colloidal silica and SBR emulsion, or further contains a silane coupling agent and / or an inorganic filler, the solvent is substantially only water, and colloidal silica and SBR. The solids weight ratio of the emulsion is in the range of 10/90 <colloidal silica / SBR emulsion <70/30.

In the present embodiment, silica dol 40 (solid content 40%) manufactured by Nippon Chemical Industry Co., Ltd. was used as colloidal silica, and A7032 (solid content 50%) manufactured by Asahi Kasei Chemicals Co., Ltd. was used as the SBR emulsion. (“Silica Doll” is a registered trademark of Nippon Chemical Industry Co., Ltd.) It consists only of colloidal silica and SBR emulsion (and water as a solvent contained therein), and has a solid content weight ratio of 10 / An aqueous coating agent having a range of 90 <colloidal silica / SBR emulsion <70/30 was prepared as Experimental Examples 1 to 5 .

  Here, since silica dol 40 as colloidal silica has a solid content of 40% and A7032 as an SBR emulsion has a solid content of 50%, the solid content weight ratio of “colloidal silica / SBR emulsion” is set to a predetermined value. Therefore, it is necessary to mix the silica doll 40 containing water as a solvent more than a predetermined solid content weight ratio with respect to A7032 containing water as a solvent. Table 1 shows the relationship between the amount of silica doll 40 and A7032 and the solid content weight ratio obtained thereby.

Further, in Experimental Example 2 , the solid content weight ratio of colloidal silica and SBR emulsion was fixed to 50/50, and not only A7032 manufactured by Asahi Kasei Chemicals Co., Ltd. but also A2245 manufactured by Asahi Kasei Chemicals Co., Ltd. as SBR emulsions. An aqueous coating agent was prepared and tested for a combination of three types of SBR emulsions of L7360 manufactured by Asahi Kasei Chemicals Corporation. The physical properties of the three types of SBR emulsions are as follows: solid content is 50%, Tg is A7032: -16 ° C, A2245: -10 ° C, L7360: -2 ° C, average particle diameter is A7032: 220 nm, A2245: 130 nm. , L7360: 200 nm.

Further, the solid content weight ratio of the colloidal silica and the SBR emulsion is fixed to 50/50 (100 parts by weight), and the silane coupling agent is within the range of 0.1 to 5 parts by weight with respect to 100 parts by weight. The aqueous coating agent added in Example 1 was prepared as Examples 1-12 . Moreover, the mixing | blending ratio of the silane coupling agent was fixed to 1 weight part, and the aqueous coating agent which added the inorganic filler in the range of 10 weight part-50 weight part to this was produced as Example 13-Example 22 . .

Here, as the silane coupling agent, KBM-403 (3-glycidoxypropyltrimethoxysilane), KBM-603 (N-2 (aminoethyl) -3-aminopropyltrimethoxy) manufactured by Shin-Etsu Chemical Co., Ltd. Silane), KBE-603 (N-2 (aminoethyl) -3-aminopropyltriethoxysilane), KBM-602 (N-2 (aminoethyl) -3-aminopropylmethyldimethoxysilane) were used. . In addition, two types of inorganic fillers were used: synthetic mica (synthetic mica) MK-100 manufactured by Corp Chemical Co., Ltd. and talc CS manufactured by Sobueclay Co., Ltd. Each formulation of Experimental Example 1 to Experimental Example 5 and Example 1 to Example 22 is shown in the upper part of Table 2 .

  On the other hand, in order to compare the properties, an aqueous solution comprising only colloidal silica and SBR emulsion (and water as a solvent contained therein) and having a solid content weight ratio of 10/90 or less or 70/30 or more. Coating agents were prepared as Comparative Examples 1 to 6. Each formulation of Comparative Examples 1 to 6 is shown in the upper part of Table 3.

The characteristics of the aqueous coating agent and the coating film of Experimental Examples 1 to 5, Experimental Examples 1 to 22, and Comparative Examples 1 to 6 are as follows: film forming property, rust prevention property, adhesion property, hardness, Six items of water resistance / cooling cycle were evaluated. The specimen to be evaluated uses a galvanized / trivalent chromate steel sheet having a length of 150 mm, a width of 70 mm, and a thickness of 0.8 mm as a base material, and an aqueous coating agent is applied to the coating film by an air spray method to a coating thickness of 30 μm. And then dried at 140 ° C. for 5 minutes.

  Regarding the film-forming property, the coated surface of the specimen prepared in this way was visually observed, and the case where there were many cracks was evaluated as “X”, the case where there were some cracks as Δ, and the case where there were no cracks as “◯”. Moreover, about rust prevention property, according to JIS-Z2371 "salt water spray test method", the coating film surface after performing a salt spray test (SST) for 2000 hours about a test piece is visually observed, 50% of the surface The case where red rust was observed was evaluated as x, the case where red rust was observed on less than 50% of the surface was evaluated as Δ, and the case where no red rust was generated was evaluated as ◯.

  Furthermore, for adhesion, according to JIS-K5400, a cross-cut tape test (1 mm width, 100 squares) was performed on the coating film of the specimen, and x was peeled even at 1 square, and no peeling was observed. Evaluated as ○. Moreover, about the hardness of the coating film, pencil hardness was measured according to JIS-K5600, the thing of 2B or less was evaluated as x, and the thing of B or more was evaluated as (circle). Further, regarding water resistance, a cross-cut tape test (1 mm width, 100 squares) was performed after immersion in warm water at 40 ° C. for 240 hours, and x was evaluated even if 1 square was peeled off, and ○ was given if there was no peeling. did.

  In addition, as a cooling cycle, after 100 cycles of a 2-hour cycle in which a specimen was placed at −20 ° C. for 1 hour and then placed at 80 ° C. for 1 hour, a cross-cut tape test (1 mm width, 100 squares) was performed. In addition, the case where even one square was peeled off was rated as x, and the case where there was no peeling was marked as ◯. Furthermore, the pencil hardness was also measured, and even when one square was peeled off and the pencil hardness was lowered by 2 ranks or more, x was not peeled and the pencil hardness was lowered by 1 rank, and the pencil hardness was lowered and the pencil hardness was lowered. Those not present were evaluated as と し て. The evaluation results for the above six items are shown in the lower part of Table 2 and the lower part of Table 3.

As shown in the lower part of Table 2, the aqueous coating agents and coating films of Experimental Examples 1 to 5 are evaluated as “good” in all of the above six items, and the aqueous coating agents of Examples 1 to 22 are used. Regarding the coating agent and the coating film, among the six items, five items of film formability, rust prevention property, adhesion, hardness, and water resistance were evaluated as “good”, and evaluated as “good” in the cooling cycle.

  Therefore, the aqueous coating agent and coating film containing colloidal silica and SBR emulsion and having a solid content weight ratio within the range of 10/90 <colloidal silica / SBR emulsion <70/30 are film-forming and rust-proofing properties.・ Evaluation of all of adhesion, hardness, water resistance, and cooling / cooling cycle is ○ or better, and water coating agent and coating film containing silane coupling agent (and inorganic filler) are also rated as ◎. It is.

  On the other hand, as shown in the lower part of Table 3, for the aqueous coating agents of Comparative Examples 1 to 3, the film forming property is evaluated as x and the following evaluation tests are performed because there are many cracks. I couldn't. Moreover, about the water-based coating agent of the comparative example 4, evaluation of film formability was (triangle | delta) and evaluation of rust prevention property was x. Thus, about the aqueous coating agent whose solid content weight ratio of colloidal silica and SBR emulsion is 70/30 or more, since the compounding rate of colloidal silica was too large, the result that it was inferior to film formability came out.

  Furthermore, as shown in the lower part of Table 3, for the aqueous coating agents of Comparative Example 5 and Comparative Example 6, the evaluation of film formability was ○, but the evaluation of rust prevention was Δ and ×, The evaluation of the hardness of the coating film was also x. As described above, the aqueous coating agent having a solid content weight ratio of colloidal silica and SBR emulsion of 10/90 or less has a result that the blending ratio of colloidal silica is too small, resulting in poor rust prevention and coating film hardness. It was.

  As described above, the aqueous coating agent contains colloidal silica and SBR emulsion, and the solid content weight ratio is within the range of 10/90 <colloidal silica / SBR emulsion <70/30. The aqueous coating agent within the range of 20/80 ≦ colloidal silica / SBR emulsion ≦ 60/40 is very excellent in film formability and rust prevention property, and furthermore, a silane coupling agent (more inorganic filler) It was revealed that the coating film formed by applying the aqueous coating agent to which the slag was added exhibited extremely excellent characteristics even with respect to the cold cycle.

  That is, by providing a silane coupling agent in the aqueous coating agent, it is a coating film that can follow the temperature change of the substrate, as is apparent from the evaluation results of the cooling cycle. On the other hand, since the coating film formed by applying an aqueous coating agent to which no silane coupling agent is added shows a reduction in pencil hardness, the film remains damaged and is considered to have insufficient stretchability. . Therefore, the molecules of the silane coupling agent are interposed between the colloidal silica particles and the SBR particles, so that the stretchability of the coating film is improved, and it is possible to expand and contract following the expansion and contraction of the base material. It is thought that.

  Moreover, since these water-based coating agents contain substantially only water as a solvent, they do not contain VOC and are extremely environmentally friendly. And since metal powder etc. are not used and compounding is easy, it can manufacture at low cost.

Thus, the water-based coating agent according to the present embodiment can improve the rust prevention property of metals such as zinc-based plated steel, has excellent film forming properties, and can be manufactured at low cost. It is environmentally friendly. Further, among the aqueous coating agents according to the present embodiment, the aqueous coating agents and coating films of Examples 1 to 22 give the coating film elasticity that can follow expansion and contraction caused by temperature changes of the substrate. An aqueous coating agent that can be applied, and a coating film having such stretchability.

  In the present embodiment, the case where silica doll 40 manufactured by Nippon Chemical Industry Co., Ltd. is used as colloidal silica and A7032, A2245 or L7360 manufactured by Asahi Kasei Chemicals Co., Ltd. is used as the SBR emulsion has been described. Other types of SBR emulsions can also be used.

  In the present embodiment, the case where the aqueous coating agent and the coating film according to the present invention are applied to a galvanized / trivalent chromate steel sheet as a zinc-based metal product has been described. However, the aqueous coating agent according to the present invention is described. In addition, the coating film can be used for rust prevention with respect to other zinc-based metal products, aluminum-based metal products, magnesium-based metal products, and the like.

  Furthermore, as the aqueous coating agent according to the modification of the present embodiment, a small amount of metal pigment, such as zinc flakes or aluminum flakes, may be added to the aqueous coating agent according to the present embodiment. Thereby, the effect that the coating film formed by applying the aqueous coating agent according to the modification of the present embodiment can be provided with conductivity as well as rust prevention is obtained.

  In practicing the present invention, other configurations, components, materials, blends, shapes, sizes, manufacturing methods, etc. of the aqueous coating agent are also included in the other configurations, components, materials, blends, shapes, sizes of the coating films. The manufacturing method and the like are not limited to the present embodiment. The numerical values raised in the embodiment of the present invention are not all critical values, and certain numerical values indicate appropriate values suitable for implementation. It does not deny implementation.

Claims (3)

An aqueous coating agent containing colloidal silica and a styrene-butadiene copolymer (SBR) emulsion,
The solid content weight ratio of the colloidal silica and the SBR emulsion is in the range of 10/90 <colloidal silica / SBR emulsion <70/30, the solvent excluding the solid content is substantially only water, and silane A coupling agent is contained within a range of 0.1 to 5 parts by weight with respect to a total solid content of 100 parts by weight of the colloidal silica and the SBR emulsion, and the silane coupling agent is composed of the colloidal silica. An aqueous coating agent characterized by imparting stretchability to a coating film formed from particles and the styrene-butadiene copolymer (SBR) emulsion molecules. The aqueous coating agent according to claim 1 , wherein the terminal of the silane coupling agent is an amino group or an epoxy group . The aqueous coating agent according to claim 1 or 2 , wherein the coating film is formed on a surface of zinc-based plated steel .