JP2010070716A - Coating material composition for forming high hardness coating film having excellent scratch resistance - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coating material composition which is used for forming a high hardness coating film and can impart practically sufficient scratch resistance to a microscope stage or the like. <P>SOLUTION: The coating material composition includes a polyamide-imide resin having a weight average molecular weight Mw in a range of 20,000-50,000, an epoxy resin in an amount of 10-50 pts.wt based on 100 pts.wt of the polyamide-imide resin, and a hard pigment. As the epoxy resin, an isocyanurate type, meta-xylenediamine type or novolac type epoxy resin having at least three epoxy groups is preferable. Further, the particle diameter of the hard pigment is preferably ≤10 μm. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a coating composition for forming a high-hardness film excellent in scratch resistance suitable for external coating such as a microscope stage.

  In general, various appearance coatings are often required to have scratch resistance to protect the appearance of the product. For example, when observing an object to be measured with a microscope, the object to be measured placed on a slide glass is fixed to a microscope stage. Since glass has high hardness and often scratches the stage surface at the edge of the slide glass, scratch resistance is required for the microscope stage surface.

  As a method for improving the scratch resistance of the microscope stage, JP-A-5-157976 (Patent Document 1) and JP-A-5-157975 (Patent Document 2) describe a thermal spray coating of ceramic paint such as alumina. It describes that a two-layered film comprising a layer and a finish film layer of a fluororesin-based coating agent as an overcoat is formed.

  However, although the protection method by the two-layer structure film composed of the sprayed coating layer and the finishing film layer improves the abrasion resistance of the microscope stage, the finishing film layer by the top coat fluororesin coating agent has low hardness, There was a problem that the slide glass was easily damaged and the appearance was impaired. Further, since it is necessary to form a two-layer structure of ceramic spraying and fluororesin coating, there is a problem that the process is troublesome and time-consuming.

  On the other hand, for the purpose of improving scratch resistance, a scratch resistance improver for coatings using a silicone compound is commercially available. However, this scratch resistance improver is used by being added to and mixed with the paint, and it is insufficient to ensure scratch resistance for a hard glass such as a slide glass and an acute edge portion. Met.

JP-A-5-157976 JP-A-5-157975

  In view of the above circumstances, a method of imparting scratch resistance to a microscope stage or the like only with a paint is desired. In order to obtain scratch resistance, it is necessary to increase the hardness of the resin coating itself. Therefore, it has been studied to increase the ratio of the hard pigment to the binding resin (binder), which is a constituent component of the resin coating forming coating. Yes. However, if the ratio of the hard pigment is increased too much, there is a problem that the coating after the coating is formed becomes brittle and consequently the scratch resistance is lowered.

  In view of such a conventional situation, the present invention provides a coating composition used for forming a high-hardness film capable of imparting practically sufficient scratch resistance to a member such as a microscope stage. Objective.

  In order to achieve the above object, the present inventor has intensively studied a coating composition for forming a high-hardness film having excellent scratch resistance. As a result, the present invention employs a polyamideimide resin and an epoxy resin as resin components, and further uses a hard pigment. By adding, the knowledge that a film having sufficient hardness can be formed only by the resin film has been obtained, and the present invention has been completed.

  That is, the coating composition for forming a high-hardness film of the present invention has a polyamideimide resin having a weight average molecular weight Mw in the range of 20,000 to 50,000 and 10 to 50 parts by weight with respect to 100 parts by weight of the polyamideimide resin. An epoxy resin and a hard pigment are included.

  In the coating composition for forming a high-hardness film of the present invention, the epoxy resin is preferably at least one selected from an isocyanurate type, a metaxylenediamine type, and a novolac type having three or more epoxy groups.

  In the coating composition for forming a high-hardness film according to the present invention, the amount of the hard pigment is preferably 10 to 200 parts by weight with respect to 100 parts by weight of the polyamideimide resin. Furthermore, the particle size of the hard pigment is preferably 10 μm or less.

  According to the present invention, it is possible to provide a coating composition capable of forming a high-hardness film having a pencil hardness of 8H or more. Therefore, the coating composition for forming a high-hardness film of the present invention can be suitably used for various appearance coatings, and in particular, forms a high-hardness film on the surface of a microscope stage or the like to greatly improve the scratch resistance. Can do.

  In the coating composition for forming a high hardness film of the present invention, an epoxy resin is combined with a polyamide-imide resin having a specific weight average molecular weight Mw as a binding resin, and a hard pigment is blended therein. The paint composition is diluted with an organic solvent as appropriate according to the purpose or application to form a paint, and the paint film coated with the paint is heat-cured to form a highly hard film with excellent scratch resistance. Can do.

  First, the result of investigating the hardness of the film of a combination of a polyamideimide resin and an epoxy resin will be described. Specifically, epoxy resin is used for three types of polyamideimide resins (manufactured by Toyobo Co., Ltd.) having a weight average molecular weight Mw of 48,000 (high molecular weight), 26,000 (medium molecular weight) and 8,400 (low molecular weight). Resin (manufactured by JER Co., Ltd., JER1001) was added and diluted with an organic solvent (manufactured by Sumiko Lubricant Co., Ltd., Sumiciner PST). Each obtained paint was spray-coated and dried, and then heated and fired at 200 to 250 ° C. for about 45 minutes in the air to form a film.

  Table 1 below shows the results of measuring the hardness of each coating obtained by the pencil scratch method defined in JIS K 5600-5-4. From this result, in the case of a polyamideimide resin having a weight average molecular weight Mw of 48,000 (high molecular weight) and 26,000 (medium molecular weight) and a coating in which 10% by weight or more of an epoxy resin is added to the polyamideimide resin, a pencil It can be seen that a scratch value of 8H or more was obtained. However, in the case of a polyamideimide resin having a weight average molecular weight Mw of less than 20,000, or a compounding amount of an epoxy resin of less than 10% by weight, a high hardness film cannot be obtained.

  From the above examination results, it was found that the weight average molecular weight Mw of the polyamideimide resin used in the present invention needs to be in the range of 20,000 to 50,000. When the weight average molecular weight Mw of the polyamideimide resin exceeds 50,000, the viscosity of the paint increases or the amount of the active ingredient decreases, so that coating of the paint becomes difficult. Further, when the weight average molecular weight Mw is less than 20,000, a sufficiently high hardness film cannot be obtained.

  The weight average molecular weight Mw of the polyamideimide resin is determined by the following method. That is, acetone is added to a varnish-like polyamideimide resin to form a precipitate, and the filtered and collected filtrate is dried. Weigh out 0.01 g of the dried filtrate and dissolve in 10 g of N, N-dimethylformamide (DMF) solution having a lithium bromide concentration of 0.03 M. The solution thus obtained is measured by gel permeation chromatography (GPC method) and detected by a differential refractometer. In the present invention, KD-G + KD-804 + KD-803 + KD-802 manufactured by Shodex was used as the separation column. The measurement conditions in the GPC method were as follows: flow rate: 1 ml / min, sample injection amount: 100 μl, column temperature: 50 ° C.

  An epoxy resin promotes hardening of a coating film by mix | blending with the said polyamidoimide resin, and contributes to formation of a coating film with high hardness. As a compounding quantity of an epoxy resin, it is set as the range of 10-50 weight part with respect to 100 weight part of polyamide resins. This is because if the blending amount of the epoxy resin is less than 10% by weight, the hardness of the coating is insufficient, and if it exceeds 50 parts by weight, the coating becomes brittle.

  Examples of the epoxy resin used in the present invention include bisphenol A type, isocyanurate type, metaxylenediamine type, and novolak type. Among these, epoxy resins having 3 or more epoxy groups in the molecule, specifically, isocyanurate type, metaxylenediamine type, and novolak type epoxy resins are preferable.

  The hard pigment is added to improve the appearance of the film, but also contributes to increasing the hardness of the film. As a compounding quantity of a hard pigment, the range of 10-200 weight part is preferable with respect to 100 weight part of polyamideimide resins. If the blending amount of the hard pigment is less than 10 parts by weight with respect to 100 parts by weight of the polyamideimide resin, the hiding power is lowered, which is not preferable. Moreover, when the compounding quantity of a hard pigment exceeds 200 weight part with respect to 100 weight part of polyamide imide resin, since a film will embrittle, it is unpreferable.

  The hard pigment used in the present invention is not particularly limited, and examples thereof include iron oxide, boron nitride, silicon nitride, silica, alumina, aluminum borate, calcined clay, and titanium boride. The particle size of the hard pigment is preferably 10 μm or less, and more preferably 5 μm or less. A finer particle size is preferable because dispersion into the resin is better and variation in appearance is reduced.

  In the coating composition for forming a high hardness film of the present invention, a predetermined amount of an epoxy resin is blended with the above-mentioned polyamideimide resin, and a hard pigment is further added and mixed. For example, it can be obtained by dispersing using a dispersing machine such as a bead mill. The obtained coating composition is diluted with an organic solvent and adjusted to a viscosity suitable for spray coating to obtain a coating material. A general-purpose organic solvent such as thinner can be used as the organic solvent for dilution of the paint.

  A coating film is obtained by spray-coating the paint obtained in this way onto the object to be protected. The film thickness of the coating film can be adjusted according to the required scratch resistance, but is about 10 to 100 μm. In order to improve the paintability of the coating film, the object to be protected is preferably preheated at 90 to 120 ° C. for several tens of minutes. After spray coating, the film is dried for several tens of minutes at 90 to 120 ° C., and then heated and baked at 200 to 250 ° C. for 30 minutes to 1 hour in the air to obtain a desired coating film.

  The film obtained using the coating composition of the present invention has a pencil hardness as high as 8H or higher, and has very good scratch resistance. In addition, the film hardness in this invention is the pencil hardness measured by the pencil scratching method prescribed | regulated to JISK5600-5-4, and the determination method was determined by the tearing of the film.

[Example 1]
Polyamideimide resin (manufactured by Toyobo Co., Ltd., Mw 26,000), epoxy resin (manufactured by JER Co., Ltd., meta-xylenediamine type), and iron oxide having a particle size of 10 μm or less as a hard pigment (manufactured by Bayer Co., Ltd.) ) Was added. At that time, as shown in Samples 1 to 5 in Table 2 below, the compounding amounts of polyamideimide resin (abbreviated as PAI resin), epoxy resin (abbreviated as EP resin), and iron oxide were changed.

  Next, an organic solvent (Sumitomo Lubricant Co., Ltd., Sumiciner PST) is added to each of the compositions of Samples 1 to 5 so that the total amount is 100% by weight, and dispersed with a bead mill. It diluted with the solvent and spray-coated on the substrate surface. Each obtained coating film was dried at 90 ° C., and further heated and fired at 230 ° C. for 30 minutes (31 minutes only for sample 5) to form coatings of Samples 1 to 5.

  About each film of the obtained samples 1-5, when hardness was measured by the pencil scratching method, the sample 1 was 8H and the samples 2-5 were all 9H. The obtained results are shown in Table 2 below.

[Example 2]
Polyamideimide resin (manufactured by Toyobo Co., Ltd., Mw 26,000), epoxy resin (manufactured by JER Co., Ltd., metaxylenediamine type) and iron oxide having a particle size of 10 μm or less as a hard pigment (manufactured by Bayer Co., Ltd.) Silica (manufactured by Mizusawa Chemical Co., Ltd.) or calcined clay was added. At that time, the compounding amount of the polyamide-imide resin, epoxy resin, iron oxide and silica or calcined clay was changed as shown in Samples 6 to 7 in Table 2 below.

  Next, an organic solvent (Sumitomo Lubricant Co., Ltd., Sumiciner PST) was added to each of the compositions of Samples 6 to 7 so that the total amount would be 100% by weight, and dispersed with a bead mill. It diluted with the solvent and spray-coated on the substrate surface. Each obtained coating film was dried at 90 ° C., and further heated and fired at 230 ° C. for 30 minutes in the air to form coatings of Samples 6 to 7.

  About each film of obtained samples 6-7, when hardness was measured by the pencil scratching method, all were 9H. The obtained results are also shown in Table 2 below.

[Comparative Example 1]
Add 10% by weight of novolak epoxy resin (Japan Epoxy Resin Co., Ltd., JER154) 10% by weight of dicyandiamide (Japan Epoxy Resin Co., Ltd., DICY7) as a hardener, and iron oxide as a hard pigment (Bayer Co., Ltd.) was added in an amount of 11.2% by weight.

  Next, an organic solvent (Sumitomo Lubricator Co., Ltd., Sumiciner PST) was added to the composition of Sample 8 of the comparative example so that the total amount was 100% by weight. And spray-coated on the substrate surface. The obtained coating film was dried at 90 ° C., and further heated and fired at 230 ° C. for 30 minutes in the air to form a coating film of Sample 8.

  It was 5H when hardness was measured by the pencil scratching method about the film of the obtained sample 8 of the comparative example. The obtained results are shown in Table 3 below.

[Comparative Example 2]
10% by weight of iron oxide (manufactured by Bayer Co., Ltd.), which is a hard pigment, was mixed with 10% by weight of Tyranopolymer (manufactured by Ube Chemical Co., Ltd.). An organic solvent (Sumitomo Lubricant Co., Ltd., Sumiciner PST) was added to the composition of Sample 9 of this comparative example so that the total amount would be 100% by weight, dispersed in a bead mill, and then diluted with the same organic solvent. Then, the substrate surface was spray-coated.

  The obtained coating film was dried at 90 ° C., and further heated and fired at 230 ° C. for 30 minutes in the air to form a coating film of Sample 9. Since cracks occurred in the obtained film, the hardness by the pencil scratching method could not be measured. The results are also shown in Table 3 below.

[Comparative Example 3]
10% by weight of iron oxide (manufactured by Bayer Co., Ltd.), which is a hard pigment, was mixed with 10% by weight of silicone resin (manufactured by Shin-Etsu Silicone Co., Ltd., KR400). To the composition of Sample 10 of this comparative example, an organic solvent (Sumitomo Lubricant Co., Ltd., Sumiciner PST) was added so as to be 100% by weight, and after dispersion with a bead mill, diluted with the same organic solvent. Then, the substrate surface was spray-coated.

  The obtained coating film was dried at 90 ° C., and further heated and fired at 230 ° C. for 30 minutes in the air to form a coating film of Sample 10. It was 4H when hardness was measured by the pencil scratching method about the film of the sample 10 of the obtained comparative example. The obtained results are also shown in Table 3 below.

  As can be seen from the results shown in Tables 2 and 3 above, in Samples 1 to 7, which are examples of the present invention, the pencil hardness of the coating film shows a high hardness of 8H or more, and has extremely excellent scratch resistance. You can see that On the other hand, in samples 8 to 10 which are comparative examples, the pencil hardness of the film was only 5H to 4H, and the hardness was remarkably insufficient to obtain scratch resistance. Further, in sample 9 of the comparative example, the coating film was cracked and a good coating film could not be formed, and therefore the coating film hardness could not be measured.

Claims (5)

  A high weight characterized by comprising a polyamideimide resin having a weight average molecular weight Mw in the range of 20,000 to 50,000, 10 to 50 parts by weight of an epoxy resin with respect to 100 parts by weight of the polyamideimide resin, and a hard pigment. A coating composition for forming a hardness film.   2. The paint for forming a high-hardness film according to claim 1, wherein the epoxy resin is at least one selected from an isocyanurate type having 3 or more epoxy groups, a metaxylenediamine type, and a novolac type. Composition.   3. The coating composition for forming a high hardness film according to claim 1, wherein the blending amount of the hard pigment is 10 to 200 parts by weight with respect to 100 parts by weight of the polyamideimide resin.   The coating composition for forming a high-hardness film according to claim 1, wherein the hard pigment has a particle size of 10 μm or less.   5. The hard pigment according to claim 1, wherein the hard pigment is at least one selected from iron oxide, boron nitride, silicon nitride, silica, alumina, aluminum borate, calcined clay, and titanium boride. A coating composition for forming a high-hardness film as described above.