JP6053416B2 - Resin composition and coating film formed therefrom - Google Patents

Description

  The present invention relates to a resin composition and a coating film formed therefrom.

  Polyester resins such as polyethylene terephthalate and polybutylene terephthalate are excellent in mechanical strength, thermal stability, hydrophobicity and chemical resistance, and are therefore widely used in various fields as molding materials such as fibers, films, and sheets. ing.

  In the polyester resin, various structures and characteristics can be obtained by appropriately selecting the combination of the types of constituent polyvalent carboxylic acid component and glycol component. The polyester resin is excellent in adhesion to the base material when coated on various base materials, and the coating film obtained by coating the polyester resin on various base materials is other Excellent adhesion to the substrate. As described above, polyester resins are widely used in applications such as adhesives, coating agents, ink binders, and paints, taking advantage of excellent adhesion and adhesiveness when formed into coating films.

  The coating film obtained from the polyester resin as described above may be laminated on the surface of a light diffusion sheet used for a liquid crystal display, LED (light emitting diode) illumination, or the like. In such a liquid crystal display and LED illumination, a multilayer structure formed by laminating a plurality of constituent members is adopted. With the recent thinning of liquid crystal displays and LED lighting, it is necessary to stack the constituent members such as the light diffusion sheet and then to compress them. Therefore, since each component member needs to have a strength enough to withstand compression, it is desired that the hardness of the coating film laminated on the surface of the light diffusion sheet is remarkably increased. Yes.

  Based on such a background, various studies have been made to improve the hardness when a polyester resin is used for a coating film. As an example, it has been studied to increase the hardness of the polyester resin by increasing the glass transition temperature (Tg) of the polyester resin (Patent Document 1). However, even in the case of Patent Document 1, there is a problem that the hardness of the obtained coating film is not yet sufficient.

  Moreover, improving the hardness at the time of setting it as a coating film is also examined by adding a hardening | curing agent with respect to a polyester resin. For example, Patent Document 2 describes a polyester resin composition containing a polyester resin and an isocyanate curing agent. Patent Document 3 describes a powder paint containing a polyester resin and an epoxy resin curing agent.

  In the case of the polyester resin composition described in Patent Document 2 and the powder coating material described in Patent Document 3, the hardness of the coating film made of the composition or the coating material is remarkably improved. However, in these documents, since a large amount of curing agent is used, when these polyester resin compositions and powder coatings are to be coated, the compositions and coatings are dissolved in an organic solvent and dissolved. After obtaining the liquid and coating the solution on the substrate and drying, it is necessary to be subjected to an aging process for several days until the coating film is further cured. There is a problem that it is inferior in productivity. In addition, since the coating film obtained by curing the polyester resin composition and the powder coating described in Patent Document 2 and Patent Document 3 is derived from a large amount of curing agent and the hardness becomes excessively high, There are problems such as poor adhesion to various substrates, and poor flexibility and flexibility when formed into a coating film, which makes it difficult to follow various shapes and makes post-processing difficult.

  Furthermore, in order to improve the post-processability (flexibility, flexibility) of the coating film obtained from the polyester resin, in Patent Document 4 and Patent Document 5, a resin composition comprising a polyester resin and a large amount of a curing agent is used. On the other hand, it has been studied to further contain organic polymer fine particles. However, even in Patent Document 4 and Patent Document 5, since a large amount of the curing agent is used, there is a problem that the adhesion to various base materials and the post-processability are not yet sufficient when a coating film is formed. is there.

JP 2010-095696 A JP 2007-39560 A Japanese Patent Laid-Open No. 10-46056 JP 2006-16486 A JP 2006-16485 A

  That is, in the prior art, without using a large amount of curing agent, the hardness when formed into a coating film is sufficiently improved, and in addition to the adhesion to various base materials and the post-processability when it is formed into a coating film It is difficult to obtain a significantly superior polyester resin composition.

  The present invention is intended to solve the above-described problems, and is remarkably excellent in hardness, adhesion to various substrates and post-workability when formed into a coating film without using a large amount of curing agent. Obtaining a resin composition is a technical problem.

  As a result of intensive studies to solve the above problems, the inventor has found a resin composition containing a polyester resin having an acid value of 10 to 50 mgKOH / g and fine particles having an average particle diameter of 1 to 30 μm. Thus, the present inventors have found that a resin composition characterized in that the content of the fine particles is 1 to 40% by mass can solve the above problems, and has reached the present invention.

That is, the gist of the present invention is as follows.
(1) Ri acid value of 12 ~ 40 mgKOH / g der, and a polyester resin having a glass transition temperature of -10～65 ° C., and an average particle size of 10 30 .mu.m crosslinked polymethyl methacrylate particles A resin composition comprising: a content of the fine particles of 10 to 40% by mass.

(2) The resin composition according to (1), wherein the number average molecular weight of the polyester resin is 2000 to 25000.

( 3 ) The resin composition according to (1) or (2), wherein the content of the curing agent is 1% by mass or less.

( 4 ) A coating formed from the resin composition of any one of (1) to ( 3 ), comprising a layer made of a polyester resin and polymethyl methacrylate fine particles having an average particle diameter of 10 to 30 μm. film.

( 5 ) The coating film according to ( 4 ), wherein the layer made of polyester resin has a thickness of 3 to 20 μm.

( 6 ) The coating film according to ( 4 ) or ( 5 ), wherein the thickness of the layer made of the polyester resin is smaller than the average particle diameter of the fine particles, and a part of the fine particles is exposed on the coating film surface.

  ADVANTAGE OF THE INVENTION According to this invention, the resin composition excellent in the hardness at the time of setting it as a coating film and adhesiveness with various base materials can be provided. Furthermore, since the coating film obtained from the resin composition of the present invention can retain sufficient flexibility and flexibility due to the resin portion existing between adjacent fine particles, Is also excellent. In addition, since the resin composition of the present invention does not require several days of aging time for forming a coating film, it is excellent in coating film productivity.

  In particular, in the coating film obtained from the resin composition of the present invention, when the thickness of the layer made of the polyester resin is thinner than the average particle diameter of the fine particles, and a part of the fine particles are exposed on the coating film surface, Due to the fine particles exposed to the surface, the hardness is superior.

It is the schematic which shows the cross section of the coating film formed from the resin composition of this invention.

Hereinafter, the present invention will be described in detail.
The resin composition of the present invention is a resin composition containing a polyester resin having an acid value of 10 to 50 mgKOH / g and fine particles having an average particle diameter of 1 to 30 μm, and the content of the fine particles is 1. It is -40 mass%, It is characterized by the above-mentioned.

First, the polyester resin will be described.
The polyester resin contained in the resin composition of the present invention plays a role as a binder resin and is composed mainly of a polyvalent carboxylic acid component and a glycol component.

  The polyvalent carboxylic acid component which is one of the main components is not particularly limited, for example, terephthalic acid, isophthalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, Sebacic acid, undecanedioic acid, dodecanedioic acid, tridecanedioic acid, tetradecanedioic acid, pentadecanedioic acid, hexadecanedioic acid, heptadecanedioic acid, octadecanedioic acid, nonadecanedioic acid, eicosanedioic acid, docosanedioic acid, phthalic acid, Naphthalenedicarboxylic acid, 4,4'-dicarboxybiphenyl, 5-sodium sulfoisophthalic acid, 5-hydroxy-isophthalic acid, fumaric acid, maleic acid, itaconic acid, mesaconic acid, citraconic acid, 1,3,4-benzenetricarboxylic acid Acid, 1,2,4,5-benzenetetracarboxylic acid, pyromellitic acid, tri Mellitic acid, oxalic acid, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 2,5-norbornenedicarboxylic acid, dimer acid, hydrogenated dimer acid, or the like Anhydrides are mentioned. Among these, terephthalic acid and isophthalic acid are preferably included from the viewpoint of durability and the like. These may be used alone or in combination of two or more.

  The glycol component, which is one of the main components, is not particularly limited. For example, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, polytetramethylene glycol, 1,4-butanediol, 1,5-pentane. Diol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-dodecanediol, 1,4-cyclohexanedi Examples include methanol, 1,3-cyclohexanedimethanol, tricyclodecane dimethanol, spiroglycol, dimer diol, neopentyl glycol, 2,2-butylethylpropanediol, 1,2-propanediol, and the like. Of these, ethylene glycol, neopentyl glycol, and 1,2-propanediol are preferable from the viewpoint of solubility. These may be used alone or in combination of two or more.

  The polyester resin may contain monomer components (other monomer components) other than the above-described polyvalent carboxylic acid component and glycol component, if necessary, as long as the effects of the present invention are not impaired. In addition, it is preferable that the copolymerization ratio of the other monomer component in a polyester resin is less than 50 mol% with respect to all the monomer components contained in a polyester resin.

  Examples of other monomer components include tetrahydrophthalic acid, lactic acid, oxirane, glycolic acid, 2-hydroxybutyric acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 2-hydroxyisobutyric acid, 2-hydroxy-2-methylbutyric acid, Hydroxycarboxylic such as 2-hydroxyvaleric acid, 3-hydroxyvaleric acid, 4-hydroxyvaleric acid, 5-hydroxyvaleric acid, 6-hydroxycaproic acid, 10-hydroxystearic acid, 4- (β-hydroxy) ethoxybenzoic acid Acid; aliphatic lactones such as β-propiolactone, β-butyrolactone, γ-butyrolactone, δ-valerolactone, and ε-caprolactone.

  Moreover, monocarboxylic acid, monoalcohol, etc. may be used as another monomer component. Examples of monocarboxylic acids include lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, benzoic acid, p-tert-butylbenzoic acid, cyclohexane acid, 4-hydroxyphenyl stearic acid, and the like. It is done. Examples of monoalcohol include octyl alcohol, decyl alcohol, lauryl alcohol, myristyl alcohol, cetyl alcohol, stearyl alcohol, 2-phenoxyethanol and the like.

  The acid value of the polyester resin used in the present invention is required to be 10 to 50 mgKOH / g, preferably 12 to 40 mgKOH / g, and more preferably 14 to 30 mgKOH / g. In the present invention, in order to increase the acid value of the polyester resin, it is necessary to subject the polyester resin to a depolymerization reaction, thereby lowering the molecular weight of the polyester resin. Therefore, when the acid value exceeds 50 mgKOH / g, there is a problem that the hardness of the coating film obtained from the resin composition containing the polyester resin is lowered due to the low molecular weight of the polyester resin. . On the other hand, when the acid value of the polyester resin is less than 10 mgKOH / g, the dispersibility of the fine particles in the polyester resin is lowered, and thus the obtained resin composition cannot be formed into a coating film. There is a problem that even if it can be made, only inferior hardness can be obtained.

  More specifically, the resin composition of the present invention is remarkably excellent in compatibility between the polyester resin and the fine particles by using a polyester resin having an acid value in a specific range as described above. Therefore, the dispersibility of the fine particles in the resin composition, or the dispersibility of the fine particles in the organic solvent when the resin composition is dissolved in the organic solvent when obtaining a coating film from the resin composition of the present invention. As a result, the dispersibility of the fine particles in the coating film obtained from the resin composition of the present invention is excellent. The excellent dispersibility of the fine particles means that the fine particles are uniformly dispersed during the stirring and that the fine particles are uniformly dispersed without aggregation or sedimentation immediately after the stirring.

  In the resin composition of the present invention, when two or more kinds of polyester resins are mixed and used, it is sufficient that the acid value of the polyester resin mixture obtained by mixing satisfies the above range. There are no particular restrictions on the combination of these and the mixing ratio of each.

  The glass transition temperature of the polyester resin is preferably -20 to 85 ° C, and more preferably -10 to 65 ° C. When the glass transition temperature of the polyester resin exceeds 85 ° C., dispersibility of the fine particles described later in the polyester resin may be insufficient, which is not preferable. On the other hand, when the glass transition temperature of the polyester resin is less than −20 ° C., the polyester resin becomes soft, so that the hardness when the obtained resin composition is used as a coating film may be unfavorable.

  The number average molecular weight of the polyester resin is preferably 2000-25000, more preferably 4000-22000, and still more preferably 6000-18000. If the number average molecular weight of the polyester resin exceeds 25000, the dispersibility of the fine particles in the polyester resin will be low, so the resulting resin composition could not be coated and could be coated. However, it is not preferable because only the inferior hardness may be obtained. On the other hand, when the number average molecular weight of the polyester resin is less than 2,000, the hardness when the obtained resin composition is used as a coating film may be unfavorable.

  In the present invention, when two or more types of polyester resins are mixed and used, it is sufficient that the glass transition temperature and the number average molecular weight of the polyester resin mixture obtained by mixing satisfy the above ranges. The combination of resins, the mixing ratio of each, etc. are not particularly limited.

  Moreover, the polyester resin used in the present invention may be crystalline or amorphous.

  In order to obtain the polyester resin as described above, for example, the following method can be used. That is, after introducing raw material monomers such as polyvalent carboxylic acid and glycol into the reaction vessel, the esterification reaction is performed. Next, a polyester resin can be produced by polycondensation until a desired molecular weight is reached by a known method. The esterification reaction is performed, for example, at a temperature of 180 ° C. or higher for 4 hours or longer.

The polycondensation reaction is generally performed using a polymerization catalyst under a reduced pressure of 130 Pa or less and a temperature of 220 to 280 ° C. Examples of the polymerization catalyst include titanium compounds such as tetrabutyl titanate, metal acetates such as zinc acetate, magnesium acetate, and zinc acetate, and organic tin compounds such as antimony trioxide, hydroxybutyltin oxide, and tin octylate. It is done. If the amount of the polymerization catalyst used is too small, the polymerization reaction may be slow, whereas if it is excessive, the color tone of the resulting polyester resin may be lowered. Therefore, it is preferable that the usage-amount of a polymerization catalyst is 0.1-20 * 10 < ^-4 > mol with respect to 1 mol of acid components. And in order to adjust the acid value of a polyester resin, following the said polycondensation reaction, polyvalent carboxylic acid can further be added and a depolymerization reaction can be performed in inert atmosphere.

Next, the fine particles will be described.
In the present invention, the fine particles are contained in the resin composition for the purpose of improving the hardness of the coating film. Examples of such fine particles include organic polymer fine particles, inorganic fine particles, and metal fine particles. In the present invention, among such fine particles, the specific organic polymer is selected from the viewpoint that the hardness of the fine particles themselves is high and the hardness when the resin composition containing the fine particles is used as a coating film can be further improved. It is preferable to use fine particles and / or metal fine particles.

  Examples of the organic polymer fine particles include fine particles made of an organic polymer such as crosslinked polymethyl methacrylate, benzoguanamine / melamine / formaldehyde condensate, methylol melamine, or urea / formaldehyde condensate. Examples of the metal particles include fine particles made of aluminum, copper, silver or iron. Among these, organic polymer fine particles are preferable from the viewpoint of excellent permeability and hardness when formed into a coating film. Among the organic polymer fine particles, crosslinked polymethyl methacrylate fine particles are particularly preferable from the viewpoint of remarkably excellent permeability and hardness when formed into a coating film.

  As the acrylic component contained in the polymethyl methacrylate constituting the fine particles, acrylic monomers include acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, sodium acrylate, ammonium acrylate, methacrylic acid, One or more selected from methyl methacrylate, ethyl methacrylate, butyl methacrylate, glycidyl methacrylate, 2-hydroxyethyl acrylate, acrylamide, methacrylamide, N-methoxymethyl acrylamide, N-methylol acrylamide and the like can be mentioned. .

  In general, the dispersibility of various fine particles with respect to the polyester resin is not good, especially when the fine particles containing an acrylic component are used because the affinity between the acrylic component and the polyester resin is low. Since both are very difficult to mix, the dispersibility of the fine particles is very poor. Therefore, when forming a resin composition containing polyester resin and fine particles, it is difficult to form a coating film, or even if a coating film is formed, the fine particles are uniformly dispersed in the coating film. There was a problem of not doing. However, in the resin composition of the present invention, as described above, a polyester resin having a specific acid value is used as the polyester resin. Therefore, even if fine particles, particularly fine particles containing an acrylic component such as polymethyl methacrylate are used, the familiarity (adhesion) between the polyester resin and the fine particles can be improved, and the dispersibility can be improved. In other words, when the coating film is formed, the arrangement of the fine particles in the coating film can be made uniform. By setting it as such a structure, the coating film excellent in hardness and post-processability can be formed.

  The average particle diameter of the fine particles needs to be 1 to 30 μm, more preferably 3 to 25 μm, and still more preferably 5 to 20 μm. When the average particle size of the fine particles exceeds 30 μm, even if a polyester resin having a specific acid value as defined in the present invention is used, it becomes difficult to disperse the fine particles in the resin composition, that is, a resin having poor dispersibility. Only a composition is obtained. In addition, even when good dispersion is achieved, when the resulting resin composition is applied to a substrate or the like to form a coating film, the original flexibility and flexibility of the coating film decrease, resulting in various shapes. There is a problem that it becomes difficult to follow the film and post-processing becomes difficult, and that the adhesion to the substrate is poor. On the other hand, if it is less than 1 μm, there is a problem that the hardness improvement effect exhibited by adding fine particles does not appear, that is, the hardness when the obtained resin composition is used as a coating film is low.

  In the resin composition of the present invention, the content of the fine particles needs to be 1 to 40% by mass, preferably 5 to 35% by mass, more preferably 10 to 30% by mass, More preferably, it is 15-25 mass%. When the content of the fine particles is less than 1% by mass, the effect of improving the hardness exhibited by adding the fine particles is not expressed, that is, the hardness when the obtained resin composition is used as a coating film is low. There is. On the other hand, if it exceeds 40% by mass, even if a polyester resin having a specific acid value specified in the present invention is used, it becomes difficult to disperse the resin, that is, only a resin composition having poor dispersibility can be obtained. Even if the dispersion can be achieved, when the obtained resin composition is applied to a substrate or the like, the content of fine particles is excessive with respect to the amount of the polyester resin as the binder resin, so that it is exposed on the surface of the coating film. When the fine particles increase, the area of the fine particles that contact the substrate becomes too large, and the required adhesion (adhesion to various substrates) cannot be obtained. In addition, since it becomes difficult to sufficiently hold the resin between adjacent fine particles, the original flexibility and flexibility of the coating film are reduced, and it is difficult to follow various shapes and post-processing is difficult. There is.

  The resin composition of the present invention contains the polyester resin as described above and fine particles having an average particle diameter of 1 to 30 μm. In the present invention, it is possible to increase the hardness of a coating film obtained for the first time without using a large amount of a curing agent by containing fine particles having a specific average particle diameter in a specific ratio. It has been found that the adhesion to the material and the flexibility can be improved. More specifically, the resin composition is excellent in all of the adhesion to the base material, the post-processability, and the hardness when it is formed into a coating film without requiring several days of aging time in forming the coating film. It was possible to get.

  In addition, by using the resin composition of the present invention, it is possible to obtain a coating film having sufficient hardness without using a curing agent, but within a range not impairing the performance of the coating film obtained in the present invention. A curing agent can also be used. When the curing agent is blended, the content of the curing agent is more preferably 1% by mass or less, and the content of the curing agent is further preferably 0.5% by mass or less.

  As a curing agent that can be blended in the resin composition of the present invention, a functional group that the polyester resin has, or a functional group that is formed by the reaction of the polyester resin (for example, a carboxyl group or its anhydride, a hydroxyl group, an epoxy group, etc.) If it consists of a compound which has the reactivity with, it will not specifically limit.

  Examples of the curing agent as described above include isocyanate compounds and various block isocyanate compounds thereof; epoxy resins; phenol resins; urea;

  In order to produce the resin composition of the present invention, for example, the following method can be employed. That is, fine particles such as organic polymer fine particles or metal fine particles are uniformly dispersed in the polyester resin obtained as described above so that the content ratio in the obtained resin composition is 1 to 40% by mass. As a method for dispersing the fine particles, the polyester resin may be dissolved in a general-purpose organic solvent, and then the fine particles may be added and dispersed by stirring. Alternatively, the fine particles may be directly kneaded into the polyester resin using an extruder or the like. The general-purpose organic solvent for dissolving the polyester resin is not particularly limited, and examples thereof include toluene, methyl ethyl ketone, alcohol, and aqueous solutions thereof.

  The resin composition of the present invention is coated (applied) on various substrates, for example, and dried as necessary to remove the organic solvent, thereby forming the coating film of the present invention on the substrate. can do. That is, the coating film of the present invention contains a layer made of a polyester resin (sometimes referred to simply as “polyester resin layer” in the present specification) and fine particles having an average particle diameter of 1 to 30 μm. .

  The substrate to be coated with the resin composition of the present invention is not particularly limited, but a film or sheet made of a resin such as a polyester resin, a polycarbonate resin, or a polyvinyl chloride resin; or an aluminum foil Or metal foils, such as copper foil, etc. are mentioned.

  The method for coating the substrate with the resin composition of the present invention is not particularly limited, and a known method such as a reverse roll coating method, a gravure coating method, a die coating method, a comma coating method or a spray coating method is used. be able to.

  In the coating film of the present invention, the thickness of the polyester resin layer is preferably 3 to 20 μm, more preferably 5 to 15 μm, and further preferably 7 to 10 μm. If the thickness of the polyester resin layer is less than 3 μm, the area of the fine particles contained in the coating film exposed to the coating film surface may become too large, thereby reducing the adhesion to the substrate. There is a case. On the other hand, if it exceeds 20 μm, the fine particles may not be sufficiently and uniformly present in the entire coating film, and as a result, the coating film hardness may be lowered. The thickness of the polyester resin layer is preferably selected arbitrarily in relation to the particle size of the fine particles used. For example, when fine particles having an average particle size of 5 μm are used, the thickness of the polyester resin layer is less than 5 μm. Thus, it is preferable to appropriately adjust the concentration of the coating liquid and the coating thickness.

  The cross section of the coating film formed from the resin composition of this invention is shown in FIG. As shown in FIG. 1, the coating film 1 formed on the surface of the substrate 2 contains a polyester resin layer 4 and fine particles 5. Furthermore, by using the resin composition of the present invention, it is possible to maintain flexibility and flexibility due to the polyester resin portion existing between adjacent fine particles, so that a coating film having excellent post-processability can be obtained. Can be formed.

  In the coating film of the present invention, it is preferable that a part of the fine particles 5 is exposed on the surface of the coating film because the thickness 3 of the polyester resin layer is thinner than the average particle diameter of the fine particles 5. By having such a configuration, the coating film is remarkably excellent in hardness due to fine particles exposed on the surface.

  In the coating film of the present invention, as shown in FIG. 1, when the thickness 3 of the polyester resin layer is thinner than the average particle diameter of the fine particles 5 and a part of the fine particles are exposed on the coating film surface, the polyester resin layer The range of the ratio of the protruding height 6 of the fine particles to the thickness 3 is preferably 1 to 50%, more preferably 5 to 45%, and still more preferably 10 to 40%. When the ratio of the protruding height 6 of the fine particles is less than 1%, the coating film hardness may be lowered. On the other hand, if it exceeds 50%, the fine particles 5 protrude excessively more than necessary on the surface of the coating film, and the adhesion to other base materials may be inferior.

  The ratio of the protrusion height 6 of the fine particles to the polyester resin layer 3 is such that the coating film obtained in the present invention is in an ideal state (that is, fine particles having a uniform average particle diameter do not overlap each other, It is preferable to be applied when the bottom surface is in contact with the substrate. For example, in the case of fine particles to be used, when the variation in particle diameter is large or the fine particles dispersed in the coating film are overlapped, the protrusion height 6 of the fine particles may be higher than necessary. Even in such a case, the thickness of the polyester resin layer can be set so as to prevent the fine particles from falling off the coating film, and the ratio of the fine particle protrusion height 6 can be increased up to 100%. . However, it is most preferable to use fine particles having a uniform average particle diameter and to set the ratio of the protruding height of the fine particles to 1 to 50% in order to simultaneously improve the coating film hardness and the post-processability. .

  The coating film formed from the resin composition of the present invention is not only excellent in hardness but also remarkably excellent in adhesion to the base material and flexibility. Therefore, it is suitably used in applications such as adhesives and coating agents. Moreover, it is also possible to use the laminated body obtained by laminating | stacking such a coating film on base materials, such as a film, further laminating | stacking on another base material.

  The coating film of the present invention can be suitably used by being laminated on various light diffusion sheets used in lighting covers, light diffusion sheets for transmissive displays, lighting signs, LED lighting, and the like. In particular, with the thinning of displays and LED lighting, it is necessary to laminate a plurality of constituent members in a multilayer structure and subject them to a compression process, but the coating film of the present invention has excellent hardness and post-processability. Therefore, the compression process can be performed without causing the coating film to fall off or break.

  Hereinafter, the present invention will be described more specifically with reference to examples. The present invention is not limited to these examples.

Evaluation methods and measurement methods are as follows.
(1) Acid value of polyester resin 1 g of the obtained polyester resin was completely dissolved in 50 ml of dioxane at room temperature, and titrated with 0.1 mol / L potassium hydroxide methanol solution using cresol red as an indicator. . And the value which divided the mg number of KOH consumed for neutralization by the g number of polyester resin was calculated | required as an acid value.

(2) Number average molecular weight of polyester resin GPC analysis using a liquid feeding unit (manufactured by Shimadzu Corporation, “LC-10ADvp type”) and an ultraviolet-visible spectrophotometer (manufactured by Shimadzu Corporation, “SPD-6AV type”) Thus, the number average molecular weight of the polyester resin was determined in terms of polystyrene. As GPC analysis conditions, the detection wavelength was 254 nm, and tetrahydrofuran was used as the solvent.

(3) Composition of polyester resin Using an NMR measuring apparatus (manufactured by JEOL Ltd., “JNM-LA400 type”), ¹ H-NMR measurement was performed, and the composition of the polyester resin was determined from the peak intensity of each monomer component. . Note that deuterated trifluoroacetic acid was used as a measurement solvent.

(4) Glass transition temperature (Tg) of polyester resin
According to JIS-K 7121, a glass transition from a chart heated at 10 ° C./min from −40 ° C. to 100 ° C. using an input-compensated differential scanning calorimeter (“Diamond DSC” manufactured by Perkin Elmer) The temperature (Tg) was read.

(5) Proportion of protrusion height of fine particles to thickness of polyester resin layer (%)
From the following formula, the ratio of the protrusion height of the fine particles to the thickness of the polyester resin layer was determined.
Ratio of protrusion height of fine particles to thickness of polyester resin layer (%) = {(average particle diameter of fine particles−thickness of polyester resin layer) / thickness of polyester resin layer} × 100

(6) Dispersibility of fine particles in resin composition The obtained resin composition was mixed with toluene and methyl ethyl ketone so that the solid content concentration was 30% by mass [(toluene) / (methyl ethyl ketone) = 8/2. , Mass ratio), the mixed solvent was shaken with a shaker for 1 hour, and then the dispersion state was visually observed and evaluated according to the following criteria.
○: Fine particles were uniformly dispersed in the mixed solvent.
Δ: Part of the fine particles was dispersed in the mixed solvent.
X: Most of the fine particles floated or settled in the mixed solvent and did not disperse.
In addition, excellent dispersibility of the fine particles in the above mixed solvent means excellent compatibility between the polyester resin and the fine particles, which means that the fine particles are dispersible in the obtained resin composition and in the coating film. It is an indicator of superiority.
In the present invention, it was determined that a circle or a triangle had practical dispersibility, and a dot was determined to have no practicality because of poor dispersibility.

(7) Hardness when coated (test using pencils with different hardness)
The resin compositions obtained in Examples , Reference Examples and Comparative Examples were mixed with toluene and methyl ethyl ketone so that the solid content concentration was 30% by mass [(toluene) / (methyl ethyl ketone) = 8/2, [Mass ratio] was dissolved to obtain a solution. The solution was applied to a copper plate using a desktop coating device (manufactured by Yasuda Seiki Co., Ltd., film applicator No. 542-AB type, bar coater device). Then, the coating film of predetermined thickness was formed by heat-processing at 100 degreeC for 30 second (s). The coating film is scratched with pencils having various hardness ("UNI" series, manufactured by Mitsubishi Pencil Co., Ltd.), and depending on the hardness of the pencil when the coating film is damaged and the tip of the pencil reaches the substrate, Evaluation based on the criteria.
A: The pencil hardness was 3H or more.
○: The pencil hardness was 2H or more and less than 3H.
(Triangle | delta): The hardness of the pencil was more than H and less than 2H.
X: The pencil hardness was less than H.
In the present invention, it was judged that those having an evaluation of Δ or more were practical, and those having x were judged not to be practical because of poor hardness.

(8) Flexibility when formed into a coating (bending test)
A coating film was formed on a PET substrate (polyethylene terephthalate substrate) as a substrate by the same method as in (6). This coating film was bent in the 180 ° direction. And the state of the coating film at the time of opening was observed visually. Evaluation was made according to the following criteria.
(Double-circle): The coating film was not cracked and the trace which bent was not left.
○: The coating film was not cracked, but a few traces were left.
(Triangle | delta): Although the coating film was not cracked, the folded mark remained strongly.
X: The coating film was cracked.
In the present invention, it was judged that those having an evaluation of Δ or more were practical, and those having x were judged not to be practical because they were inferior in flexibility.

(9) Adhesion (cross-cut test)
A coating film was formed on a PET substrate (polyethylene terephthalate substrate) and a copper foil as a substrate by the same method as (6). In these coating films, incisions were made according to the cross-cut method defined in JIS K5600-5-6 to form 100 squares. Then, the adhesive tape (width 18 mm) prescribed | regulated to JISZ1522 was affixed leaving the edge part in the direction parallel to one direction of a cutting direction, and rubbed with the eraser from this adhesive tape, and was fully adhere | attached. Next, the pressure-sensitive adhesive tape was pulled in the direction of an angle of 60 ° with respect to the sticking surface and peeled off instantaneously. After peeling off the adhesive tape, the number of squares remaining in the coating film was visually measured and evaluated according to the following criteria.
A: The remaining squares were 95 or more.
○: The remaining squares were 90 sheets or more and less than 95 sheets.
Δ: The remaining squares were 70 sheets or more and less than 90 sheets.
X: The number of remaining squares was less than 70.
In the present invention, it was judged that those with an evaluation of Δ or more were practical, and those with x were judged to have no practicality because of poor adhesion of the coating film.

(10) Comprehensive evaluation (circle): There is no evaluation of x in the evaluation result of said (6)-(9).
X: Among the evaluation results (6) to (9), there is one or more evaluations of x.

(Preparation of polyester resin)
Preparation Example 1
82 g (49.5 mol%) of terephthalic acid, 82 g (49.5 mol%) of isophthalic acid, 43 g (70 mol%) of ethylene glycol, 68 g (65 mol%) of neopentyl glycol, and 0.4% of tetrabutyl titanate as a polymerization catalyst. 1 g was charged into the reactor, and the inside of the system was replaced with nitrogen. And while stirring these raw materials at 1000 rpm, the reactor was heated at 245 ° C. and melted. After the temperature in the reactor reached 245 ° C., the esterification reaction was allowed to proceed for 3 hours. After 3 hours, the temperature in the system was set to 250 ° C., and the pressure in the system was reduced. After the inside of the system reached a high vacuum (pressure: 0.1 to 10 ⁻⁵ Pa), a polymerization reaction was further performed for 3.0 hours. After releasing the pressure reduction, 1.9 g (1.0 mol%) of trimellitic acid as a depolymerizing agent was added, and a depolymerization reaction was performed at 245 ° C. for 2 hours to obtain a polyester resin A.

Preparation Examples 2-14
Except having changed the preparation composition of the polyester resin as shown in Table 1, the same operations as in Preparation Example 1 were performed to obtain polyester resins B to N. In Preparation Example 14, not only the charge composition was changed, but the polyester resin N was obtained when the polycondensation reaction was completed without performing the depolymerization reaction. Table 1 shows the monomer charge composition and the polymerization reaction time in the polyester resins A to N obtained in Preparation Examples 1 to 14.

In addition, the abbreviation in Table 1 and Table 2 mentioned later shows the following, respectively.
TPA: terephthalic acid IPA: isophthalic acid EG: ethylene glycol PG: propylene glycol NPG: neopentyl glycol PTMG1000: polytetramethylene glycol TMA: trimellitic acid

In addition, the types (I) to (IX) of the fine particles in Table 1 and Table 2 described below are as follows.
(I): Cross-linked polymethyl methacrylate fine particles (manufactured by Soken Chemical Co., Ltd., “MX-1000”, average particle size: 10 μm)
(II): Cross-linked polymethyl methacrylate fine particles (manufactured by Sekisui Plastics Co., Ltd., “SSX-101”, average particle size: 1 μm)
(III): Cross-linked polymethyl methacrylate fine particles (manufactured by Sekisui Plastics Co., Ltd., “MBX-20”, average particle size: 30 μm)
(IV): Non-crosslinked polymethyl methacrylate fine particles (manufactured by Matsumoto Yushi Seiyaku Co., Ltd., “M101”, average particle size: 20 μm)
(V): Methylolmelamine fine particles (manufactured by Nippon Carbide Industries, “Nikaresin S-260”, average particle size: 10 μm)
(VI): Copper powder (manufactured by Fukuda Metal Foil Powder Industry Co., Ltd., “FCC-SP-77”, average particle size: 10 μm)
(VII): Silver powder (manufactured by Tanaka Kikinzoku Co., Ltd., “AY-6010”, average particle size: 10 μm)
(VIII): Cross-linked polymethyl methacrylate fine particles (manufactured by Sekisui Plastics Co., Ltd., “Eposter MX200W”, average particle size: 0.4 μm)
(IX): Cross-linked polymethyl methacrylate fine particles (manufactured by Sekisui Plastics Co., Ltd., “MBX-40”, average particle size: 40 μm)

Example 1
30 g of the polyester resin A obtained in Preparation Example 1 was mixed with 70 g of a mixed solvent of toluene and methyl ethyl ketone [(toluene) / (methyl ethyl ketone) = 8/2, mass ratio] so that the solid content concentration was 30% by mass. Dissolved. Then, 6 g of fine particles (I) (20% by mass with respect to the resin solid content) was further added, and then shaken for 1 hour to uniformly disperse the fine particles I to obtain the resin composition of the present invention. . From the obtained resin composition, a coating film having a polyester resin layer thickness of 8 μm was formed and evaluated on the PET film and the copper foil by the methods (6) and (7) in the evaluation method. It was attached to. The results of Example 1 are shown in Table 2.

Examples 3-5, 9-14, 17, 18, 21, Reference Examples 1-12 and Comparative Examples 1-7
A resin composition was obtained in the same manner as in Example 1 except that the type of polyester resin used and the type and content of fine particles were changed as shown in Tables 2 and 3. From the obtained resin composition, as shown in Table 2 and Table 3, a coating film in which the thickness of the polyester resin layer was changed was formed and evaluated by the same method as in Example 1. The results are shown in Tables 2 and 3.

なお、表３中、比較例１および比較例５においては、後述のように塗膜を得ることができなかったが、基材上に樹脂組成物を塗布した状態で可とう性の評価をおこなった。

In Table 3, in Comparative Example 1 and Comparative Example 5, the coating film could not be obtained as described later, but the flexibility was evaluated in a state where the resin composition was applied on the substrate. It was.

As is clear from Tables 2-3, the resin compositions obtained in Examples 1 , 3-5, 9-14, 17, 18, 21 are excellent in the dispersibility of the contained fine particles. It was excellent in hardness and adhesion to the substrate when it was made a coating film.

  The resin composition obtained in Comparative Example 1 was unable to form a coating film because the acid value of the polyester resin used was too low and the dispersibility of the fine particles in the polyester resin was low.

  The resin composition obtained in Comparative Example 2 was inferior in hardness when formed into a coating film because the acid value of the polyester resin used was too high.

  The resin composition obtained in Comparative Example 3 was inferior in hardness when formed into a coating film because the content of fine particles was too small.

  The resin composition obtained in Comparative Example 4 was inferior in adhesion and flexibility to the substrate when it was formed into a coating film because the content of fine particles was excessive.

  In the resin composition obtained in Comparative Example 5, the acid value of the polyester resin used was too low, and in addition, the glass transition temperature of the polyester resin was higher than the preferred range in the present invention. Therefore, the dispersibility of the fine particles in the resin composition was low, and a coating film could not be formed.

  The resin composition obtained in Comparative Example 6 was inferior in hardness when used as a coating film because the average particle size of the fine particles used was too small.

  The resin composition obtained in Comparative Example 7 was inferior in adhesion to the base material and flexibility in the coating film because the average particle size of the fine particles used was excessive. .

DESCRIPTION OF SYMBOLS 1 Coating film 2 Base material 3 Polyester resin layer thickness 4 Polyester resin layer 5 Fine particle 6 Protrusion height of fine particle

Claims (6)

Acid value 12 ~ 40 mgKOH / g der is, and a resin containing a polyester resin having a glass transition temperature of -10～65 ° C., and an average particle size of 10 30 .mu.m crosslinked polymethyl methacrylate particles a composition, a resin composition content of the fine particles being 10 40 mass%.   The number average molecular weight of a polyester resin is 2000-25000, The resin composition of Claim 1 characterized by the above-mentioned. Content of a hardening | curing agent is 1 mass% or less, The resin composition of Claim 1 or 2 characterized by the above-mentioned. A coating comprising a layer made of a polyester resin and crosslinked polymethyl methacrylate fine particles having an average particle diameter of 10 to 30 µm formed from the resin composition according to any one of claims 1 to 3. film. The thickness of the layer which consists of polyester resins is 3-20 micrometers, The coating film of Claim 4 characterized by the above-mentioned. Thinner than the average particle diameter of the layer thickness fine particles comprising a polyester resin, a coating film according to claim 4 or 5 part of the fine particles on the film surface and wherein the exposed.

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