JP5036974B2 - Powder containing ethylene-vinyl alcohol copolymer and powder coating comprising the same - Google Patents

Description

  The present invention relates to a powder containing an ethylene-vinyl alcohol copolymer and a powder coating comprising the same. The present invention also relates to a multilayer structure formed by applying the powder coating on a base material and a drain pipe.

  Conventionally, powder coating has attracted attention as a technique for protecting a substrate mainly made of metal from rust, corrosion, or a solvent. Powder coating is a promising coating method in the future, especially because in recent years the use of solvent-based paints has been refrained to reduce environmental impact, and production speed can be increased and costs can be reduced. Expected. As the powder coating resin, powder made of polyethylene, polyamide, epoxy resin, acrylic resin or the like is used.

  However, since these resins have insufficient gas barrier properties and / or chemical resistance, it is necessary to make the coating film considerably thicker. Alternatively, since the interlayer adhesion between the metal surface and the coating film made of such resin is insufficient, the metal surface has to be pretreated with a primer or the like before coating.

  In order to solve the above problems, Patent Document 1 discloses a method using an ethylene-vinyl alcohol copolymer (hereinafter sometimes abbreviated as EVOH) powder as a resin for powder coating.

  Furthermore, in a molded article coated with EVOH powder, the method of improving the uniformity of the coating film thickness and improving the impact resistance of the coating film surface includes an ethylene content of 15 to 70 mol%, a vinyl acetate component A low-boiling compound containing 0.0001 to 1 part by weight of an acidic compound and having a boiling point of 200 ° C. or lower is 0.1% with respect to 100 parts by weight of EVOH having a saponification degree of 80 mol% or more and a melt index of 1 to 100 g / 10 min. Patent Document 2 discloses a resin composition for powder coating containing 1-1 part by weight. The publication describes that the low boiling point compound having a boiling point of 200 ° C. or lower is preferably water from the viewpoint of safety and the environment. In addition, it is also described that when the content of the low boiling point compound having a boiling point of 200 ° C. or less is 1 part by weight or more, unevenness on the surface of the coating film becomes severe in the thermal spraying method involving rapid temperature increase.

  In addition, Patent Document 3 discloses that a resin composition for powder coating comprising EVOH, polyamide and an olefin-unsaturated carboxylic acid copolymer has good impact resistance, organic solvent resistance, and impact resistance. It is disclosed.

  Patent Document 4 discloses that a resin composition containing EVOH and a polyamide-based resin having a melting point of 160 ° C. or less has good alkali resistance and impact resistance.

Furthermore, in Patent Document 3 , an antioxidant is added to a resin composition for powder coating made of EVOH, polyamide and an olefin-unsaturated carboxylic acid copolymer, to the resin composition and powder coating from the viewpoint of preventing thermal deterioration. Although there is no description about adding a specific amount of a specific antioxidant, the cleaning agent resistance of a multilayer structure in which such powder is applied to a pipe or the like as a powder coating is improved. There is no mention or suggestion to do. Moreover, it does not describe the combined use with a phosphoric acid heat stabilizer.

Prior art documents related to the present invention include the following.
Japanese Patent Laid-Open No. 3-115472 JP-A-9-241537 JP 2000-248205 A JP 2002-363476 A

  When a powder composed of EVOH or EVOH resin composition is applied by the above technique, a coating film with improved impact resistance and good organic solvent resistance, acid resistance, and alkali resistance can be obtained. However, when it is used to paint drainage pipes for domestic wastewater from toilets, kitchens, washing machines, etc., resistance to chlorine compounds contained in various disinfectants, bleaches, toilet cleaners, etc. is required. The resistance to chlorine compounds is not high, and especially when exposed to a strong cleaning agent such as hypochlorite for a long time, the resin easily deteriorates and the strength of the coating film rapidly decreases. In addition, when constructing drainage pipes, etc. at construction / construction sites, it is very difficult to carry out construction without bringing the pipes into contact with other hard objects at all, but the impact resistance of the coating film is poor at this time. If it is sufficient, the coating film will crack, and if it is severe, the coating film will peel off. If it becomes like this, the maintenance of the favorable external appearance which is a function of painting, corrosion resistance, etc. will be lost.

  Therefore, a paint having both good detergent resistance and impact resistance has been required for painting drainage pipes and the like.

  The present invention has been made to solve the above-described problems, and provides a powder having good impact resistance and detergent resistance while having suitable performance inherent to EVOH or an EVOH composition. It is for the purpose. It is another object of the present invention to provide a powder coating composed of such powder, a multilayer structure formed by applying the powder coating on a substrate, and a drain pipe. Furthermore, it is an object of the present invention to provide a powder that is excellent in smoothness and has a good gloss even when powder coating is performed using a moisture-absorbed powder.

The above-mentioned problems include an ethylene-vinyl alcohol copolymer (A), a resin composition comprising a resin (B) having an affinity for the ethylene-vinyl alcohol copolymer (A), an antioxidant (C) and phosphorus. A powder (P) comprising a thermal stabilizer (D), wherein the weight ratio A / B of (A) to (B) is 40/60 to 98/2 in the powder (P). The weight ratio (A + B) / C of (A) and (B) to (C) is 100 / 0.005 to 100/20, and the sum of (A) and (B) And the weight ratio (A + B) / (C + D) of the sum of (C) and (D) is 100 / 0.005 to 100/20, and the ethylene-vinyl alcohol copolymer (A) is ethylene 2-60 mol% content ethylene saponification degree of 85 mol% or more - a vinyl alcohol copolymer, said ethylene The resin (B) having an affinity for the vinyl-vinyl alcohol copolymer (A) is composed of a carboxyl group, a carboxylic ester group, a carboxylic anhydride group, a carboxylic acid group, an ester bond, a urethane bond and an amide bond. Core-shell polymer particles having a glass transition temperature of −10 ° C. or lower and a shell component having a glass transition temperature of 30 ° C. or higher and a thermoplastic resin having a functional group capable of reacting with at least one hydroxyl group selected from B6) and at least one resin selected from the group consisting of saponified ethylene-vinyl acetate copolymers (B7) having an ethylene content of 70 to 95 mol% and a saponification degree of 85 mol% or more, and the oxidation The inhibitor (C) is selected from the group consisting of phenolic antioxidants, hindered phenolic antioxidants and vitamin E antioxidants. That the powder is at least one antioxidant is accomplished by providing.

Further, the resin (B) having an affinity for the ethylene-vinyl alcohol copolymer (A) is a polyolefin (B1) having a functional group capable of reacting with a hydroxyl group, and an aromatic vinyl having a functional group capable of reacting with a hydroxyl group. A block copolymer (B2) comprising a polymer block and a hydrogenated conjugated diene polymer block; a polyester (B3) having a glass transition temperature of −150 to 25 ° C. and a crystal melting heat of 30 J / g or less; a thermoplastic polyurethane ( It is more preferable if it is at least one thermoplastic resin selected from the group consisting of B4) and polyamide resin (B5).

The functional group capable of reacting with the hydroxyl group of the block copolymer (B2) comprising the aromatic vinyl polymer block and the hydrogenated conjugated diene polymer block is a carboxyl group, a carboxylic ester group, or a carboxylic anhydride group. and it is preferable that a thermoplastic resin having 10~1000μeq / g at least one functional group selected from carboxylic acid salt group or Ranaru group.

It is also preferable that the powder (P) contains inorganic fine particles (E), and the inorganic fine particles (E) are more preferably silica particles or alumina particles having an average primary particle diameter of 1 to 100 nm. .

  Furthermore, it is preferable that the particle diameter of the powder (P) is 22 to 850 μm.

  A powder coating material comprising the above powder is a preferred embodiment of the present invention. A multilayer structure formed by applying the powder coating material onto a substrate is also a preferred embodiment of the present invention. This multilayer structure can be expected to have good detergent resistance. Furthermore, a drain pipe excellent in cleaning agent resistance obtained by applying the powder coating on a substrate is also a preferred embodiment of the present invention.

  When the resin mixture of the present invention is used as a powder coating, the coating applied to the substrate is very impact resistant to coating, hardness of the coating (pencil hardness), uniformity of coating, and detergent. A product with excellent properties can be obtained. In particular, the present invention is excellent in that good detergent resistance that cannot be achieved with a normal EVOH composition is obtained.

  The EVOH (A) used in the present invention is preferably one obtained by saponifying an ethylene-vinyl ester copolymer. A typical vinyl ester used in the production of EVOH is vinyl acetate, but other fatty acid vinyl esters (such as vinyl propionate and vinyl pivalate) can also be used. In addition, other comonomer, for example, α-olefin such as propylene, butylene, isobutene, 4-methyl-1-pentene, 1-hexene, 1-octene, etc., as long as the object of the present invention is not hindered; Unsaturated carboxylic acids such as (meth) acrylic acid, methyl (meth) acrylate, and ethyl (meth) acrylate or esters thereof; vinylsilane compounds such as vinyltrimethoxysilane; unsaturated sulfonic acids or salts thereof; alkylthiols A vinyl pyrrolidone such as N-vinyl pyrrolidone can also be copolymerized.

  As EVOH (A), it is preferable to use a modified EVOH which is modified with an olefinically unsaturated monomer containing silicon and whose modification amount is 0.0002 to 0.5 mol%. When the powder made of EVOH is applied to a substrate, the interlayer adhesive strength between the coating film and the substrate is improved. In particular, when the substrate is a metal, the improvement effect is great. When the modification amount of EVOH by the olefinically unsaturated monomer containing silicon is less than 0.0002 mol%, the effect of improving the interlayer adhesion strength between the coating film and the substrate cannot be sufficiently obtained. On the other hand, when the modification amount exceeds 0.5 mol%, the fluidity at the time of melting of the resin is lowered, and the coating film surface tends to be uneven. The more preferable amount of EVOH modified by the silicon-containing olefinically unsaturated monomer is 0.001 to 0.1 mol%, and more preferably 0.005 to 0.07 mol%. Is 0.01 to 0.05 mol%.

  Here, examples of the vinylsilane compound include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri (β-methoxy-ethoxy) silane, and γ-methacryloxypropylmethoxysilane. Of these, vinyltrimethoxysilane and vinyltriethoxysilane are preferably used.

Ethylene content of the EVOH (A) used in the present invention is Ru 2-60 mol% der. When ethylene content exceeds 60 mol%, there exists a possibility that the gas barrier property and chemical-resistance of EVOH (A) obtained may become inadequate. The upper limit of the ethylene content is more preferably 57 mol% or less, further preferably 54 mol% or less, and most preferably 51 mol% or less. On the other hand, when the ethylene content is less than 2 mol%, the resulting powder coating containing EVOH (A) may be too hard and the impact resistance of the coating may be insufficient. . Further, the lower the ethylene content, the higher the melting point of the obtained EVOH (A), while the decomposition start temperature tends to be lower, so the range of operating conditions in which powder coating is possible becomes narrower. From this viewpoint, the lower limit of the ethylene content of EVOH (A) is more preferably 5 mol% or more, further preferably 10 mol% or more, particularly preferably 15 mol% or more, and most preferably It is 20 mol% or more. EVOH (A) may be a blend of two or more types of EVOH having different ethylene contents. In this case, the average value calculated from the blending weight ratio is taken as the ethylene content.

  Furthermore, the saponification degree of the vinyl ester component of EVOH (A) used in the present invention is preferably 90 mol% or more. The saponification degree of the vinyl ester component is more preferably 95 mol% or more, further preferably 98 mol% or more, and optimally 99 mol% or more. When the saponification degree is less than 90 mol%, the gas barrier property and chemical resistance of the coating film may be insufficient. Here, when EVOH (A) is composed of a blend of two or more types of EVOH having different saponification degrees, the average value calculated from the blending weight ratio is defined as the saponification degree.

  The ethylene content and saponification degree of EVOH (A) can be determined by a nuclear magnetic resonance (NMR) method.

  Furthermore, EVOH blended with a boron compound can be used as EVOH (A) within a range that does not interfere with the object of the present invention. Examples of the boron compound include boric acids, boric acid esters, borates, borohydrides, and the like. Specific examples of boric acids include orthoboric acid, metaboric acid, and tetraboric acid. Examples of boric acid esters include triethyl borate and trimethyl borate. Examples include alkali metal salts of acids, alkaline earth metal salts, and borax. Among these compounds, orthoboric acid (hereinafter sometimes simply referred to as boric acid) is preferable.

  When EVOH (A) in which a boron compound is blended is used as EVOH (A), the content of the boron compound is preferably 20 to 2000 ppm, more preferably 50 to 1000 ppm in terms of boron element. By blending the boron compound within this range, it is possible to obtain an effect that cracks hardly occur even when a large deformation such as bending is applied.

  Moreover, you may use EVOH (A) which mix | blended the phosphoric acid compound as EVOH (A). Thereby, the quality (coloring, etc.) of the resin may be stabilized. It does not specifically limit as a phosphoric acid compound used for this invention, Various acids, such as phosphoric acid and phosphorous acid, its salt, etc. can be used. The phosphate may be contained in any form of primary phosphate, secondary phosphate, and tertiary phosphate, but primary phosphate is preferred. The cationic species is not particularly limited, but is preferably an alkali metal salt. Among these, sodium dihydrogen phosphate and potassium dihydrogen phosphate are preferable. When EVOH (A) containing a phosphoric acid compound is used, the content of the phosphoric acid compound is preferably 200 ppm or less, more preferably 5 to 150 ppm, and most preferably 5 to 150 ppm in terms of phosphate radical. 100 ppm.

  The intrinsic viscosity of EVOH (A) used in the present invention is preferably 0.057 L / g or more. The intrinsic viscosity of EVOH (A) is more preferably in the range of 0.059 to 0.110 L / g, further preferably 0.062 to 0.097 L / g, and particularly preferably 0.066 to 0.00. 087 L / g. When the intrinsic viscosity of EVOH (A) exceeds 0.110 L / g, when used as a powder coating, the fluidity of the resin is lowered, and the coating film surface may be uneven. Moreover, when the intrinsic viscosity of EVOH (A) is less than 0.057 L / g, the thickness of the coating film may be uneven.

  A suitable melt flow rate (MFR) (190 ° C., under a load of 2160 g) of EVOH (A) used in the present invention is 3 to 150 g / 10 minutes, more preferably 0.5 to 120 g / 10 minutes, It is preferably 8 to 90 g / 10 minutes, particularly preferably 10 to 60 g / 10 minutes. However, those having a melting point near 190 ° C. or exceeding 190 ° C. were measured under a load of 2160 g and at a plurality of temperatures above the melting point, and in a semilogarithmic graph, the reciprocal absolute temperature was plotted on the horizontal axis, and the logarithm of MFR was plotted on the vertical axis. The value is extrapolated to 190 ° C. Two or more types of EVOH (A) having different MFRs can also be mixed and used.

The resin (B) having an affinity for the ethylene-vinyl alcohol copolymer (A) of the present invention is preferably a thermoplastic resin having a functional group capable of reacting with a hydroxyl group.

Suitable functional groups capable of reacting with a hydroxyl group, a carboxyl group, a carboxylic acid ester group, carboxylic anhydride group, a carboxylic acid salt, an ester bond, a urethane bond and an amide bond can be exemplified.

  In the present invention, the weight ratio A / B of EVOH (A) and the resin (B) having affinity with EVOH (A) is preferably 40/60 to 98/2. If the weight fraction of (B) exceeds 60%, EVOH's good surface hardness, chemical resistance, adhesive properties and other properties will deteriorate, and if it is less than 2%, the impact resistance will not be improved sufficiently. It becomes. A more preferable range of A / B is 55/45 to 97/3, more preferably 50/50 to 96/4, and most preferably 60/40 to 95/5.

  Examples of the polyolefin (B1) having a functional group capable of reacting with a hydroxyl group include homopolymers such as high-density or low-density polyethylene, polypropylene, and polybutene-1, and ethylene, propylene, 1-butene, 1-hexene, and 1-octene. , A copolymer of α-olefins selected from 4-methyl-1-pentene or the like, or a copolymer of an α-olefin and other copolymer components, and the like, carboxylic acid, carboxylate salt, and boronic acid And those modified with a boron-containing group, an isocyanate group, an amide group, an epoxy group or the like that can be converted to a boronic acid group in the presence of a group or water. Of these, polyolefins modified with at least one of carboxylic acids, carboxylates, and boron-containing groups that can be converted to boronic acid groups in the presence of boronic acid groups or water are impact resistant with small additions. Desirable for improvement and economic efficiency.

  Examples of the modification method include a method of copolymerizing a vinyl compound having the above functional group, a method of adding to a double bond present in a trace amount in a polyolefin, a method of grafting and introducing a functional group into a side chain. The The modification method other than copolymerization is not particularly limited, such as a method of reacting in a solution or a method of reacting in an extruder.

  In the present invention, the block copolymer (B2) comprising an aromatic vinyl polymer block having a functional group capable of reacting with a hydroxyl group and a hydrogenated conjugated diene polymer block (B2) is a polymer block of a vinyl aromatic compound ( S) and a conjugated diene compound block (O) having an unsaturation level not exceeding 20 mol%, and a block copolymer hydrogenated product (a) generally represented by a structure of S—O or S—O—S ) A modified block copolymer hydrogenated product obtained by addition reaction of 0.1 to 10 parts by weight of a compound having a functional group capable of reacting with a hydroxyl group or a derivative thereof at 100 parts by weight.

  The molecular structure of S—O or S—O—S may be linear, branched, radial, or a combination thereof, and a mixture of S—O and S—O—S structures is used. May be. Further, as the block copolymer hydrogenated product (B2), a mixture of an unmodified block copolymer hydrogenated product and a modified block copolymer hydrogenated product may be used.

  The vinyl aromatic compound content in the hydrogenated block copolymer (B2) is 10 to 90% by weight, preferably 10 to 50% by weight, and one or two of styrene, α-methylstyrene, vinyltoluene and the like. More than one species can be selected and used. As the conjugated diene compound, one or more kinds selected from butadiene, isoprene, 1,3-pentadiene and the like can be used.

  Examples of the functional group capable of reacting with a hydroxyl group in the hydrogenated block copolymer (B2) include a carboxyl group, a carboxylic acid ester group, a carboxylic acid anhydride group, a carboxylic acid group, a boronic acid group, a boronic acid ester group, and boron. An acid anhydride group, a boronate group and the like are exemplified as preferable ones. These functional groups may be used alone or in combination. The amount of the functional group capable of reacting with a hydroxyl group is preferably 10 to 1000 μeq / g with respect to the hydrogenated block copolymer. More preferably, it is 20-500microeq / g, More preferably, it is 40-250microeq / g.

  The polyester resin (B3) of the present invention having a glass transition temperature of −150 to 25 ° C. and a crystal melting heat of 30 J / g or less is an aromatic dicarboxylic acid such as terephthalic acid or isophthalic acid, adipic acid or sepacic acid, etc. And one or more dicarboxylic acids such as aliphatic dicarboxylic acids and a diol component having 2 to 6 carbon atoms such as ethylene glycol, 1,3-propanediol, 1,4-butanediol, and 1,6-hexanediol. It is a condensed product. When the glass transition temperature is less than −150 ° C., the polyester resin is easily stuck, so that it is difficult to perform a mixing operation with EVOH (A), and when it exceeds 25 ° C., the impact resistance improving effect is insufficient. In addition, when the heat of crystal fusion exceeds 30 J / g, the impact resistance improvement effect is insufficient. A more preferable range of the glass transition temperature is −80 to −10 ° C. The heat of crystal melting is more preferably 10 to 20 J / g.

  The glass transition temperature of the polyester resin (B3) can be controlled by the ratio of aromatic acid to aliphatic acid in the resin, and the glass transition temperature can be lowered by increasing the amount of aliphatic acid. Further, the heat of crystal fusion can be lowered by increasing the amount of a component (for example, phthalic acid) that disturbs the crystallinity of the resin.

  The glass transition temperature of the polyester resin (B3) is measured with a differential scanning calorimeter (DSC) under the condition of a heating rate of 10 ° C./min, and the heat of crystal melting is the condition of the heating rate of 20 ° C./min with DSC. Measured in

  The thermoplastic polyurethane (B4) in the present invention is a melt-moldable polyurethane resin, and usually comprises two or three components such as a high molecular diol and an organic diisocyanate, and / or a low molecular diol.

  The polymer diol is a diol of a polymer compound obtained by polycondensation, addition polymerization (for example, ring-opening polymerization) or polyaddition, and representative examples include polyester diol, polyether diol, polycarbonate diol, or these The cocondensate is raised. You may use these individually or in mixture of 2 or more types. These polymer diols have an average molecular weight in the range of 500 to 3000, preferably 500 to 2500.

  Examples of organic diisocyanates include 4,4-diphenylmethane diisocyanate, tolylene diisocyanate, 1,3- or 1,4-bis (isocyanatomethyl) benzene, 1,3- or 1,4-bis (isocyanatomethyl) cyclohexane, 4, Aromatic, alicyclic or aliphatic diisocyanates such as 4′-dicyclohexylmethane diisocyanate and isophorone diisocyanate can be mentioned. You may use these individually or in mixture of 2 or more types.

  As the low molecular weight diol, a low molecular weight diol having a molecular weight of less than 500, such as ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, 1,4-bishydroxyethylbenzene, and the like And aliphatic, alicyclic or aliphatic diols. You may use these individually or in mixture of 2 or more types.

  The polyamide resin (B5) in the present invention is not particularly limited. For example, polycaproamide (nylon-6), polyundecanamide (nylon-11), polylauryllactam (nylon-12), poly Aliphatic polyamide homopolymers such as hexamethylene adipamide (nylon-6, 6) and polyhexamethylene sebacamide (nylon-6, 12); caprolactam / lauryl lactam copolymer (nylon-6 / 12), Caprolactam / aminoundecanoic acid copolymer (nylon-6 / 11), caprolactam / ω-aminononanoic acid copolymer (nylon-6 / 9), caprolactam / hexamethylenediammonium adipate copolymer (nylon-6 / 6, 6) Caprolactam / hexamethylene diammonium adipate / f Aliphatic polyamide copolymers such as samethylene diammonium sebacate copolymer (nylon-6 / 6, 6/6, 12); polymetaxylylenediamine adipate (MX-nylon), hexamethylene diammonium terephthalate / hexa An aromatic polyamide such as methylene diammonium isophthalate copolymer (nylon-6T / 6I) can be used. These polyamide resins can be used alone or in combination of two or more.

  Of these polyamide resins, polyamide resins containing a caproamide component (for example, nylon-6, nylon-6, 12, nylon-6 / 12, nylon-6 / 6, 6, etc.) are preferable.

  In the present invention, the core-shell polymer particle (B6) having a glass transition temperature of the core component of −10 ° C. or lower and a glass transition temperature of the shell component of 30 ° C. or higher is a multilayer structure (two layers) mainly composed of a thermoplastic resin. Particles having a structure or higher) and having a resin outer shell layer (shell component) having a glass transition point of 30 ° C. or higher and a core portion (core component) of resin having a glass transition temperature of −10 ° C. or lower. When the glass transition temperature of the shell component is less than 30 ° C., the adhesive force / cohesive force between the particles becomes large, so that uniform dispersion in EVOH (A) becomes difficult. Moreover, when the glass transition temperature of a core component exceeds -10 degreeC, the impact-resistant improvement effect becomes inadequate. The outer shell layer and / or core portion of the core-shell polymer particle (B6) may be formed of a plurality of resin layers satisfying the glass transition temperature, and in that case, the core-shell polymer particle (B6) has a three-layer structure or more.

  The configuration of the core-shell polymer particle (B6) is not particularly limited, but it is preferable to use a diene polymer such as butadiene or isoprene as the core component from the viewpoint of improving impact resistance. It is also preferable to use a vinyl monomer copolymerizable with a diene monomer, for example, a copolymer of styrene or acrylonitrile and a diene monomer. As a general resin as a shell component, a polymer of a methacrylic ester such as methyl methacrylate or ethyl metal acrylate, or a copolymer of a methacrylic ester and an aromatic vinyl compound such as styrene or acrylonitrile is preferably used. Used. Further, it is also preferable to modify the shell component with a functional group having an affinity for EVOH such as a small amount of carboxylic acid compound by copolymerization or grafting in order to obtain good dispersibility in EVOH (A).

  The production method of the core-shell polymer particles (B6) is not particularly limited. First, emulsion polymerization is performed using a conjugated diene monomer, and then a monomer capable of forming a shell component is added to the reaction system. A method of obtaining the target core-shell polymer particles by performing emulsion polymerization is exemplified. In the emulsion polymerization method, a chain transfer agent such as octyl mercaptan or lauryl mercaptan can be used as necessary according to known means. In addition, after emulsion polymerization, the core shell polymer particles (B6) can be separated and obtained from the polymer latex according to a known method, for example, by coagulation drying.

  The ethylene-vinyl acetate copolymer saponified product (B7) having an ethylene content of 70 to 95 mol% and a saponification degree of 85 mol% or more in the present invention is not particularly limited. Examples thereof include a polymerized polymer dissolved in methanol and saponified using sodium hydroxide as a catalyst. If the ethylene content is less than 70 mol%, the impact resistance improving effect is insufficient, and if it exceeds 95 mol%, uniform dispersion becomes difficult due to insufficient compatibility with EVOH (A). Also, when the degree of saponification is less than 85 mol%, poor dispersion due to insufficient compatibility with EVOH (A) occurs. Furthermore, it is also possible to modify the saponified ethylene-vinyl acetate copolymer with a functional group having an affinity with EVOH such as a small amount of carboxylic acid compound by copolymerization or grafting, etc., and good dispersibility in EVOH (A) It is preferable to obtain As a specific technique, a small amount of maleic anhydride / ester is copolymerized.

Antioxidant (C) of the present invention, a phenolic antioxidant, at least one antioxidant selected from the group consisting of hindered phenolic antioxidants and vitamin E antioxidant. Examples of these antioxidants include 2,5-di-t-butylhydroquinone, 2,6-di-t-butyl-p-cresol, 4,4′-thiobis- (6-t-butylphenol), 2 , 2′-methylene-bis- (4-methyl-6-tert-butylphenol), octadecyl-3- (3 ′, 5′-di-tert-butyl-4′-hydroxyphenyl) propionate, 4,4′- thiobis - (6-t-butylphenol), pentaerythritol tetrakis [3- (3 ', 5'-di -t- butyl-4' - hydroxyphenyl) propionate], N, N'-hexane-1,6-diylbis [3- (3 ', 5'-di -t- butyl-4' - hydroxy phenylpropyl Ona bromide), 3,4-dihydro-2,5,7,8-tetramethyl-2- (4 ', 8' , 12'-trimethyltride Le) -2H- Benzobiran-6-ol, etc. are exemplified. Among these, pentaerythritol tetrakis [3- (3 ', 5'-di -t- butyl-4' - hydroxyphenyl) propionate], N, N'-hexane-1,6-diyl bis [3- (3 ', 5 '- di -t- butyl-4' - hydroxy phenylpropyl Ona bromide), 3,4-dihydro-2,5,7,8-tetramethyl-2- (4 ', 8', 12'-trimethyl tridecyl) -2H-benzobilan-6-ol is suitable because it can exert its effect when added in a small amount. These antioxidants may be used alone or in combination.

  These antioxidants are usually added to prevent deterioration due to oxygen in the air at the time of resin melt molding or under use conditions after molding. EVOH (A) and EVOH (A ) The resin composition consisting of the resin (B) having an affinity for), by adding an antioxidant, it can be exposed to chlorine compounds contained in disinfectants, bleaches, toilet cleaners, etc. for a long time.・ It is possible to stop the deterioration of strength within a practically acceptable range. Of course, suppression of deterioration due to oxygen in the air, which is an effect of a normal antioxidant, can also be expected.

  The method of adding the antioxidant (C) in the present invention to the resin composition comprising EVOH (A) and the resin (B) having affinity for EVOH (A) is not particularly limited, but (A), ( B) and (C) are mixed by a tumbler, so-called dry blending, or separately using a measuring feeder, each component is supplied to an extruder so as to have a predetermined composition ratio and a predetermined amount, and melted. A method of kneading, a method of dissolving (A) and (B) in a suitable solvent, dissolving / dispersing (C) in the solution, and then removing the solvent by a suitable method, or (A) or ( (B) is dissolved in a suitable solvent, (C) is dissolved / dispersed in the solution to remove the solvent, and then (B) or (A) is melt-kneaded with an extruder, or (A) + ( The method of adding and mixing the powder of (C) to the resin powder of B) It is shown. Among these, from the viewpoint of reducing the man-hours and processing costs, (A), (B) and (C) are mixed with a tumbler or the like, or each component is separately used with a predetermined composition ratio and a predetermined amount. A method in which the amount is supplied to the extruder and melt-kneaded is preferable.

  The content of the antioxidant (C) with respect to the resin composition comprising EVOH (A) and the resin (B) having affinity with EVOH (A) is the sum of (A) and (B), (C ) And the weight ratio (A + B) / C is preferably in the range of 100 / 0.005 to 100/20. When the content of (C) is less than 0.005 parts by weight with respect to 100 parts by weight of (A + B), the improvement of the detergent resistance is insufficient, and when it exceeds 20 parts by weight, it is uniformly dispersed. The appearance is likely to deteriorate due to bleeding out to the surface of the resin layer. A more preferable range of the weight ratio (A + B) / C of the sum of (A) and (B) and (C) is 100 / 0.01 to 100/10, more preferably 100/0. 03 to 100/5, and most preferably 100 / 0.05 to 100/1.

The above antioxidants, if used together Li emissions based heat stabilizer (D), it is possible to obtain a higher detergent resistance. The phosphorus-based heat stabilizer (D) in the present invention is not particularly limited, but tris (2,4-di-t-butylphenyl) phosphite, bis [2,4-bis (1,1-dimethylethyl) Examples include -6-methylphenyl] ethyl ester phosphorous acid, bis (2,4-di-t-butylphenyl) pentaerythritol diphosphite, and the like. These phosphorus heat stabilizers may be used alone or in combination.

  The contents of the antioxidant (C) and the phosphorus-based heat stabilizer (D) in the resin composition comprising EVOH (A) and the resin (B) having affinity for EVOH (A) are (A) and ( The weight ratio (A + B) / (C + D) of the sum of (B) and the sum of (C) and (D) is preferably in the range of 100 / 0.005 to 100/20. When the content of (C + D) is less than 0.005 parts by weight with respect to 100 parts by weight of (A + B), the improvement of the detergent resistance is insufficient. The appearance is likely to deteriorate due to bleeding out to the surface of the resin layer. A more preferable range of the weight ratio (A + B) / (C + D) of the sum of (A) and (B) and the sum of (C) and (D) is 100 / 0.02 to 100/10. More preferably, it is 100 / 0.06 to 100/5, and most preferably 100 / 0.1 to 100/1.

  The addition method of the antioxidant (C) and the phosphorus-based heat stabilizer (D) in the present invention to the resin composition comprising EVOH (A) and the resin (B) having affinity for EVOH (A) is particularly Although it is not limited, (A), (B), (C), (D) are mixed with a tumbler or the like, or separately using a weighing feeder so that each component has a predetermined composition ratio and a predetermined amount. A method of supplying to an extruder and melt-kneading, (A) and (B) are dissolved in an appropriate solvent, (C) and (D) are dissolved / dispersed in the solution, and then the solvent is added by an appropriate method. Method of removing, or (A) or (B) is dissolved in a suitable solvent, (C) and (D) are dissolved / dispersed in the solution to remove the solvent, and then (B) or A method of melt-kneading (A) and the resin compositions of (A) and (B) A method of adding and mixing the powder of the body (C) + (D) is exemplified. Of these, (A), (B), (C) and (D) are dry blended with a tumbler, etc., or a predetermined amount is separately supplied to the extruder from the viewpoint of reducing man-hours and processing costs. The melt kneading method is preferred.

  Moreover, as long as the object of the present invention is not impaired, the powder (P) used in the present invention is reinforced with plasticizers, pigments, ultraviolet absorbers, antistatic agents, crosslinking agents, fillers, various fibers and the like. It is also possible to add an appropriate amount of an agent or the like. In particular, when the powder (P) of the present invention is used as a powder coating material, it is preferable to use a powder (P) in which a pigment is blended. These may be melt-kneaded into the powder (P) before pulverizing the powder (P) or may be dry blended after pulverization, but from the viewpoint of being uniformly dispersed in the powder (P) It is more preferable to melt knead when producing a resin composition comprising EVOH (A) and a resin (B) having an affinity for EVOH (A) before pulverization. In addition, a dispersant such as a higher fatty acid may be added in order to improve the dispersibility of these additives within a range that does not impair the object of the present invention.

  Moreover, if it is a range which does not inhibit the objective of this invention, the resin composition which mix | blended thermoplastic resins other than resin (B) which has affinity with EVOH (A) as powder (P) used for this invention It is also possible to use. As the thermoplastic resin, various polyolefins (polyethylene, polypropylene, poly 1-butene, poly 4-methyl-1-pentene, ethylene-propylene copolymer, copolymers of ethylene and α-olefins having 4 or more carbon atoms, ethylene, -Vinyl ester copolymer, ethylene-acrylic ester copolymer, polyvinyl chloride, polyvinylidene chloride, polyester having a heat of crystal fusion of 30 J / g or more, polystyrene, polyacrylonitrile and the like are used.

  The resin composition obtained as described above needs to be pulverized unless it is already a powder. The processing method is not particularly limited, but is a mechanical pulverization method using freeze pulverization or a jet mill, and further a method in which the resin mixture is dissolved in a suitable solvent and then dispersed and precipitated in a fine powder in a poor solvent. Etc. are exemplified.

It is also preferable that the powder (P) contains inorganic fine particles (E) from the viewpoint of improving the appearance of the coating film. The inorganic fine particles (E) are more preferably silica particles or alumina particles having an average primary particle diameter of 1 to 100 nm. The inorganic fine powder usually forms secondary particles in which the individual particles are loosely aggregated. In the present invention, the diameter of the individual particles forming the secondary particles is defined as the inorganic fine particles (E). The average diameter of primary particles. The average primary particle diameter is determined by measuring the primary particle diameter on a photograph taken with a transmission electron microscope.

  When the average primary particle diameter of the inorganic fine particles (E) is less than 1 nm, it becomes difficult to produce the inorganic fine particles (E), and when mixing the powder (P) and the inorganic fine particles (E), It becomes difficult to mix homogeneously. Therefore, when the resin mixture is used as a powder coating, the uniformity of the coating film becomes insufficient. On the other hand, even when the average primary particle diameter of the inorganic fine particles (E) exceeds 100 nm, the uniformity and smoothness of the coating film are insufficient when the resin mixture is used as a powder coating.

  The lower limit of the average diameter of the primary particles of the inorganic fine particles (E) used in the present invention is more preferably 3 nm or more, further preferably 5 nm or more, and most preferably 7 nm or more. On the other hand, the upper limit of the average diameter of the primary particles of the inorganic fine particles (E) used in the present invention is more preferably 85 nm or less, further preferably 70 nm or less, and most preferably 55 nm or less.

  Although it does not specifically limit as inorganic fine particle (E) used for this invention, A silica, aluminum oxide, a talc, a titanium oxide, a calcium carbonate etc. are illustrated as a suitable thing. Of these, talc, titanium oxide, and calcium carbonate each have a unique color, which may hinder the coloring of the resin mixture of the present invention with a pigment or the like. Further, when the resin mixture of the present invention is used as a powder coating material, it is desirable that the inorganic fine particles (E) are excellent in transparency even when it is required to form a transparent coating film on the substrate. From this point of view, silica and aluminum oxide having good transparency are particularly suitable as the inorganic fine particles (E) used in the present invention.

  Moreover, although the exact reason is unknown, the effect of the present invention is more remarkably achieved by using the inorganic fine particles (E) whose surfaces are hydrophobized as the inorganic fine particles (E) used in the present invention. be able to. That is, when the resin mixture of the present invention is used as a powder coating, the uniformity of the coating film is further improved. The surface of the inorganic fine particles (E) can be hydrophobized by a known method, and examples thereof include a method of treating with halogenated silanes, alkoxysilanes, siloxanes and the like.

  In the present invention, the content of the inorganic fine particles (E) in the powder (P) is not particularly limited, but the inorganic fine particles (E) are added in an amount of 0.0001 to 100 parts by weight of the powder (P). 2 parts by weight is preferred. In particular, in a more preferred embodiment, the powder (P) is characterized in that inorganic fine particles (E) are adhered to the surface of the resin mixture powder.

  The particle size of the powder (P) used in the present invention is preferably 22 to 850 μm. That is, the standard sieve standard shown in JIS standard Z-8801 contains 80% by weight or more of the total powder (P) that passes through a sieve having a nominal size of 850 μm and does not pass through a 22 μm sieve. By using the powder (P) having such a particle diameter, when the powder of the resin mixture mainly composed of the ethylene-vinyl alcohol copolymer of the present invention is used as a powder coating, the surface of the coating film can be made uniform. An excellent molded product can be obtained. When the content of the powder (P) passing through the 22 μm sieve is 20% by weight or more, the particles of the powder (P) are easily aggregated, and the coating film surface is likely to be uneven. On the other hand, even when less than 80% by weight of the whole powder (P) passes through the 850 μm sieve, fine irregularities are easily formed on the coating film surface and the smoothness is poor. The particle diameter of the powder (P) used in the present invention is more preferably 26 to 710 μm, further preferably 32 to 600 μm, and most preferably 38 to 500 μm.

  The method for mixing the powder (P) and the inorganic fine particles (E) in the present invention is not particularly limited. Preferred methods include dry blending of powder (P) and inorganic fine particles (E), pellets of resin composition comprising EVOH (A) and resin (B) having affinity for EVOH (A), and After the inorganic fine particles (E) are dry-blended, the resulting composition is pulverized, the powder (P) and the inorganic fine particles (E) are suspended in a liquid (water, etc.), thoroughly stirred and then removed. Liquid / drying method, stirring the powder (P) in a dry state, adding a suspension of inorganic fine particles (E) in a liquid (water, etc.), mixing thoroughly, and then dehydrating and drying A method etc. are illustrated as a suitable thing. Among these, from the viewpoint of simplicity and productivity, the powder (P) and the inorganic fine particles (E) are dry blended, or the EVOH (A) and the EVOH (A) have an affinity. A method of pulverizing the resulting mixture after dry blending the resin composition pellets made of the resin (B) and the inorganic fine particles (E) is more preferable.

  The moisture content of the powder (P) of the present invention is not particularly limited, but from the viewpoint of the uniformity of the coating film obtained when the resin mixture of the present invention is used as a powder coating, the upper limit of the moisture content of the resin mixture Is preferably less than 6% by weight, more preferably 4% by weight or less, further preferably 3% by weight or less, and further preferably 2.5% by weight or less.

  The resin mixture of the present invention is preferably used as a powder coating material. Such a powder coating can be used in various powder coating methods. Examples of the powder coating method include a fluid dipping method, an electrostatic coating method, a thermal spraying method, and a rotational molding method. The coating temperature condition varies depending on the coating method and the melting point of the copolymer, but is preferably about 150 to 300 ° C. at the substrate surface temperature.

  Examples of the base material to be coated with the resin mixture of the present invention include metals such as steel pipes and steel plates. Usually, these metals are subjected to pretreatment such as degreasing, phosphate treatment, and plating as necessary in order to improve adhesion to the coating film, corrosion resistance, appearance, and the like. The resin mixture of the present invention can also be used for painting ceramics, ceramics, glass, plastics and the like.

  As described above, a multilayer coating is obtained by applying a powder coating composed of the resin mixture of the present invention on a base material represented by a metal by powder coating. At this time, it is free to perform multilayering with other resin layers as necessary. As the structure of the multilayer structure when multilayered with other resin layers, the base material is M, the layer formed by applying the resin mixture of the present invention is E, and the other resin layers are P1 and P2. For example, various configurations such as M / E / P1, M / P1 / E, M / P1 / E / P2, and the like are included, but the present invention is not limited thereto.

  Other resins laminated with the layer formed by applying the resin mixture of the present invention include olefins such as various polyethylenes, polypropylenes, ethylene-vinyl acetate copolymers, or copolymers thereof; carboxylic acid-modified polyolefins; polyethylenes Polyester / polyester elastomers such as terephthalate; various polyamide resins such as nylon-11 and nylon-12; polyvinyl chloride; polyvinylidene chloride; acrylic resins; thermoplastic resins such as polyurethane elastomers, thermosetting epoxy resins, thermosetting And a single product or a mixture of modified acrylic resins, thermosetting urethane resins, thermosetting polyester resins, or modified products of these resins.

  The method of combining the resin mixture layer of the present invention with another resin layer is not particularly limited, but a method of performing powder coating multiple times, melting a resin mixture and a mixture of one or more other resins. And a method in which two or more resin layers are obtained by a single coating by phase separation due to a difference in affinity. Among these, the method of performing powder coating a plurality of times does not need to consider the affinity between resins and can be easily implemented.

  The multilayer structure including the layer formed from the powder (P) thus obtained has improved detergent resistance and impact resistance in addition to EVOH's good solvent resistance and gas barrier properties. Have.

  In addition, if powder coating is carried out on a pipe-shaped base material using the powder of the present invention, EVOH has good solvent resistance and gas barrier properties, and has practically no problem with detergent resistance and resistance. An impact drainage pipe can be obtained.

EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to this Example. Hereinafter, “%” and “parts” are based on weight unless otherwise specified. Here, Example 9 relates to a powder not containing the phosphorus-based heat stabilizer (D), and is described for reference. Examples of the present invention are only Examples 1 to 8 and Examples 10 and 11.

Synthesis example 1
A polymerization reaction vessel having a volume of 200 L was charged with 83.1 kg of vinyl acetate and 8.4 kg of methanol, and oxygen in the polymerization vessel was replaced with ethylene gas. The temperature in the polymerization vessel was adjusted to 60 ° C., and ethylene gas was introduced into the vessel and pressurized to increase the pressure to 6.18 MPa. When the temperature and pressure were stabilized, 150 g of azobisisovaleronitrile dissolved in 3 kg of methanol was charged into the polymerization vessel to start the polymerization reaction. After 4 hours, the temperature in the polymerization vessel was cooled to 20 ° C., and at the same time, a solution in which 0.2 g of copper acetate was dissolved in 20 kg of methanol was put into the vessel to stop the polymerization reaction. The polymerization rate of vinyl acetate at the end was 35 mol%.

  After purging the ethylene gas in the polymerization vessel, the polymerization solution was extracted from the vessel and diluted with 20 L of methanol. This liquid is fed from the top of the tower vessel, methanol vapor is fed from the bottom of the tower, unreacted monomers remaining in the polymerization liquid are removed together with methanol vapor, and a methanol solution of ethylene-vinyl acetate copolymer is obtained. Obtained. The ethylene content in the polymer was 47 mol%, and the polymer concentration in the solution was 43%.

  The methanol solution of the obtained ethylene-vinyl acetate copolymer was charged into a saponification reactor, and the caustic soda / methanol solution (80 g / L) was 0.4 equivalents relative to the vinyl ester component in the copolymer. And methanol was added to adjust the polymer concentration to 20%. The mixture was heated to 60 ° C. and stirred for about 4 hours while blowing nitrogen gas into the reactor. After 4 hours, acetic acid was added. The saponification degree of the obtained ethylene-vinyl alcohol copolymer (EVOH) was 99.5 mol%.

  The obtained EVOH methanol solution was heated to 80 ° C. to evaporate excess methanol until the polymer concentration was 43.3%. Thus, 5.61 parts by weight of water was added to 100 parts by weight of the EVOH methanol solution thus obtained to obtain a methanol / water solution having a polymer concentration of 41%. The solvent composition at this time was methanol / water = 91/9% by weight. This methanol / water solution of EVOH was extruded from a metal plate having a circular opening into a bath having a composition of methanol / water = 10/90% by weight at 5 ° C. to obtain a strand-like precipitate. The obtained strand was cut to obtain EVOH pellets having a diameter of about 3 mm and a length of about 5 mm. The operation of draining the obtained EVOH pellets with a centrifuge and adding a large amount of water to drain was repeated.

  845 weight of an aqueous solution containing 100 parts by weight of the EVOH water-containing pellets thus obtained (water content 55%) containing 0.4 g / L of acetic acid, 0.28 g / L of calcium acetate and 0.075 g / L of potassium dihydrogen phosphate. It was immersed in the part at 25 ° C. for 6 hours. After immersion, the solution was drained and dried at 80 ° C. for 3 hours and then at 107 ° C. for 24 hours using a hot air dryer to obtain dry EVOH pellets. Using the obtained dry EVOH pellets, the amounts of carboxylic acid, phosphoric acid compound, and various metal ions contained in EVOH were measured according to the following method.

(1) Determination of content of carboxylic acid 20 g of dried EVOH pellets were put into 100 ml of ion-exchanged water and extracted by heating at 95 ° C. for 6 hours. The extract was neutralized and titrated with 1/50 N NaOH using phenolphthalein as an indicator, and the acid content was determined by multiplying the number of moles of the acid by the molecular weight. Furthermore, using the extract, SCS5-252 manufactured by Yokogawa Electric Corporation was used for the column, and each carboxyl anion was identified by ion chromatography using 0.1% phosphoric acid aqueous solution as an eluent. .

(2) Determination of alkali metal ions and alkaline earth metal ions 10 g of dry EVOH pellets used as samples were put into 50 ml of 0.01 N hydrochloric acid aqueous solution and stirred at 95 ° C. for 6 hours. The aqueous solution after stirring was quantitatively analyzed by ion chromatography to quantify the amount of metal ions. The column used was ICS-C25 manufactured by Yokogawa Electric Corporation, and the eluent was an aqueous solution containing 5.0 mM tartaric acid and 1.0 mM 2,6-pyridinedicarboxylic acid. For the determination, calibration curves prepared from aqueous solutions of various metal salts such as sodium chloride aqueous solution, potassium chloride aqueous solution, magnesium chloride aqueous solution and calcium chloride aqueous solution were used. From the amounts of alkali metal ions and alkaline earth metal ions thus obtained, the amounts of alkali metal salt and alkaline earth metal salt in the dried pellets were obtained in terms of metal elements.

(3) Quantitative determination of phosphoric acid compound 10 g of dry EVOH pellets used as a sample were put into 50 ml of 0.01 N hydrochloric acid aqueous solution and stirred at 95 ° C. for 6 hours. The aqueous solution after stirring was quantitatively analyzed using ion chromatography to quantify the amount of phosphate ions. The column used was ICS-A23 manufactured by Yokogawa Electric Corporation, and the eluent was an aqueous solution containing 2.5 mM sodium carbonate and 1.0 mM sodium bicarbonate. A calibration curve prepared with an aqueous sodium dihydrogen phosphate solution was used for the determination. From the amount of phosphate ions thus obtained, the content of the phosphate compound was obtained in terms of phosphate radical.

  The carboxylic acid contained in the obtained dry EVOH pellets was acetic acid, and its content was 310 ppm. The content of calcium salt contained in the EVOH pellets was 72 ppm in terms of metal element, the content of potassium salt was 37 ppm in terms of metal element, and the content of phosphate compound was 52 ppm in terms of phosphate group. Further, the MFR (measured under a load of 2160 g at 190 ° C.) of the obtained EVOH resin pellet was 30 g / 10 minutes.

(4) Intrinsic Viscosity 0.20 g of dry EVOH pellets used as a sample was precisely weighed and dissolved in 40 ml of hydrous phenol (water / phenol = 15/85) at 60 ° C. for 3 to 4 hours to reach a temperature of 30 ° C. Then, it was measured with an Ostwald viscometer (t0 = 90 seconds), and the intrinsic viscosity [η] was determined by the following equation.
[Η] = (2 × (ηsp−lnηrel)) ^1/2 / C (L / g)
ηsp = t / t0-1
ηrel = t / t0
C: EVOH concentration (g / l)
T0: Time for blank (hydrous phenol) to pass through viscometer t: Time for hydrous phenol solution in which sample is dissolved to pass viscometer

  The intrinsic viscosity [η] of the EVOH was 0.0740 L / g.

  As EVOH (A), 90 parts of the dried EVOH pellet obtained in Synthesis Example 1 and polyolefin (B1) having a functional group capable of reacting with a hydroxyl group, Admer NF-550 (maleic anhydride modified linear) manufactured by Mitsui Chemicals, Inc. 10 parts of low density polyethylene) and 0.1 parts of Irganox 1098 (hindered phenol antioxidant) manufactured by Ciba Specialty Chemicals Co., Ltd. D) 0.1 part of Irgafos 168 manufactured by Ciba Specialty Chemicals Co., Ltd. was dry-blended using a tumbler, and this was a small twin screw extruder with a kneading part (labor plast mill small size manufactured by Toyo Seiki Co., Ltd.) Extruder 2D25W type) to obtain blend pellets. The extrusion temperature was 190 ° C., the screw rotation speed was 150 rpm, and the discharge rate was about 6 kg / hour. Moreover, MFR (measured under a 2160-g load of 190 degreeC) of the obtained blend pellet was 25 g / 10min.

  The blended pellets were cooled with liquid nitrogen and applied to a pulverizer to obtain powders having a particle size of 45 to 425 μm (that is, the obtained powders passed through a sieve having a nominal size of 425 μm according to JIS standard sieve specifications, and 45 μm). The powder that does not pass through the sieve is contained at 80% by weight or more of the whole powder). To 100 parts of this powder, 0.1 part of Aerosil R972 (silica powder with an average primary particle diameter of 16 nm, dimethylsilyl group surface-treated product) manufactured by Nippon Aerosil Co., Ltd. was added as inorganic fine particles (E), and the mixture was shaken well. A powder (P) made of a resin mixture containing an ethylene-vinyl alcohol copolymer as a main component was obtained. The water content in the resin mixture powder at this time was 1.4%. The water content in the resin mixture powder was measured according to the following method.

(5) Determination of moisture content of EVOH composition Using HR73 halogen moisture content analyzer manufactured by METLER, moisture content of EVOH composition (X) under the conditions of a drying temperature of 180 ° C, a drying time of 20 minutes, and a sample amount of about 2 g. Was measured.

The surface of an iron plate 0.8 mm thick × 50 mm × 100 mm was washed with a detergent. The iron plate was coated with a powder coating composed of the EVOH composition produced above by a fluid immersion method. After preheating the iron plate in advance, air is blown through the perforated plate into the fluid chamber, the resin powder is flowed, and the substrate made of the iron plate is immersed in the fluidized bed, and then heated. went. The flow immersion conditions are shown below.
・ Preheating of iron plate: temperature 280 ° C., time 10 minutes ・ Immersion time: 5 seconds ・ Postheating: temperature 200 ° C., time 5 minutes

  Using the iron plate coated with the obtained powder as described above, impact resistance, coating film hardness (pencil hardness), and coating film uniformity were evaluated according to the following criteria.

(6) Impact resistance Place the iron plate coated with the obtained resin mixture powder on the concrete floor with the powder coated surface facing up, and drop a 530g iron ball from a height of 1m onto the center of the iron plate The damage condition of the coating film was confirmed.
Judgment Criteria A (pass): No crack occurred B (pass): Although fine cracks occurred, no peeling of coating film C (failed): Large cracks occurred, coating film peeled off

(7) Pencil Hardness The pencil hardness of the coating film was evaluated by a hand scratch method with a pencil scratch value defined in 8.4.2 of JIS K5400.

(8) Uniformity of coating film The appearance of the obtained coating film was visually observed and judged as follows.
Judgment Criteria A (Pass): Good uniformity of coating film B (Pass): Slightly uneven but no practical problem C (Fail): Uneven and uneven

(9) Cleaning agent resistance Instead of using 0.8 mm thick x 50 mm x 100 mm iron plate, powder coating is performed under the same conditions as the above iron plate using a 1 mm thick x 50 mm (outer diameter) x 100 mm long steel pipe The test piece of the painted drainage pipe was obtained. Using this test piece, the detergent resistance was evaluated according to the following criteria.

Toilet hyter manufactured by Kao Corporation (containing surfactant, sodium hydroxide and hypochlorite) is diluted with water to prepare a 10% solution. A test piece of a drainage pipe coated with the obtained powder was immersed in this solution at 40 ° C. for 2 weeks, and changes in appearance before and after immersion were confirmed.
Judgment criteria A (accepted): No change in appearance B (accepted): Gloss slightly decreased, but no significant change in coating film strength C (failed): Resin deteriorated into powder when rubbed by hand Peeling off

  Based on the above criteria, impact resistance, coating film hardness (pencil hardness), coating film uniformity, and detergent resistance were evaluated using the iron plate coated with the EVOH powder obtained in this example. . The impact resistance was B, the coating film uniformity and detergent resistance were both A, and the pencil hardness was F.

  The resin (B) having an affinity for EVOH (A) is a block copolymer (B2) comprising an aromatic vinyl polymer block having a functional group capable of reacting with a hydroxyl group and a hydrogenated conjugated diene polymer block. A blend pellet was obtained in the same manner as in Example 1, except that Tuftec M1962 (maleic anhydride-modified styrene-butadiene thermoplastic elastomer) manufactured by Asahi Kasei Corporation was used. The blend pellet obtained had an MFR (measured at 190 ° C. under a load of 2160 g) of 22 g / 10 min. The blended pellets were pulverized in the same manner as in Example 1 and blended with inorganic fine particles (E). Further, in the same manner as in Example 1, the obtained powder was used in a fluid dipping method for iron plates and pipes. Using powder coated iron plates and pipes obtained by powder coating, the impact resistance, coating film hardness (pencil hardness), coating film uniformity, and detergent resistance were evaluated. It was. The evaluation results are shown in Table 1.

  As a resin (B) having an affinity for EVOH (A), it is a polyester (B3) having a glass transition temperature of −150 to 25 ° C. and a crystal melting heat of 30 J / g or less. A blend pellet was obtained in the same manner as in Example 1 except that (polybutylene terephthalate-polyether block copolymer) was used. The MFR (measured under a load of 2160 g at 190 ° C.) of the obtained blend pellets was 24 g / 10 minutes. This blend pellet was pulverized in the same manner as in Example 1 and blended with inorganic fine particles (E) to obtain a powder. The moisture content in the powder at this time was 1.2%. Further, in the same manner as in Example 1, powder coating was performed on the iron plate and pipe using the fluid dipping method using this powder, and the iron plate and pipe coated with the obtained powder were used for impact resistance. The coating film hardness (pencil hardness), coating film uniformity, and detergent resistance were evaluated. The evaluation results are shown in Table 1.

  As a resin (B) having an affinity for EVOH (A), Kuraray Co., Ltd. Kuramylon U1180 (polyester thermoplastic polyurethane), which is a thermoplastic polyurethane (B4), is used. Blend pellets were obtained in the same manner as in Example 1 except that the temperature was changed to ° C. The MFR (measured under a load of 2160 g at 190 ° C.) of the obtained blend pellet was 20 g / 10 minutes. The blended pellets were pulverized and blended with inorganic fine particles (E) in the same manner as in Example 1 to obtain a powder composed of a resin mixture. The water content in the powder at this time was 1.0%. Further, in the same manner as in Example 1, powder coating was performed on the iron plate and pipe using the powder by the flow dipping method, and the impact resistance and hardness of the coating film were measured using the powder-coated iron plate and pipe. (Pencil hardness) / Coating film uniformity / Cleaning agent resistance was evaluated. The evaluation results are shown in Table 1.

  As resin (B) having an affinity for EVOH (A), polyamide resin (B5), Amilan CM6541X3 (6/12 copolymer polyamide) manufactured by Toray Industries, Inc. was used in the same manner as in Example 1. Blended pellets were obtained. MFR (measured under a load of 2160 g at 190 ° C.) of the obtained blend pellet was 28 g / 10 minutes. The blended pellets were pulverized and blended with inorganic fine particles (E) in the same manner as in Example 1 to obtain a powder composed of a resin mixture. The moisture content in the powder at this time was 1.1%. Further, in the same manner as in Example 1, powder coating was performed on the iron plate and pipe using the powder by the flow dipping method, and the impact resistance and hardness of the coating film were measured using the powder-coated iron plate and pipe. (Pencil hardness) / Coating film uniformity / Cleaning agent resistance was evaluated. The evaluation results are shown in Table 1.

  Blend pellets were obtained in the same manner as in Example 5, except that the weight ratio A / B of EVOH (A) and polyamide resin (B5) was changed to 50/50. The MFR (measured under a load of 2160 g at 190 ° C.) of the obtained blend pellets was 17 g / 10 minutes. The blended pellets were pulverized and blended with inorganic fine particles (E) in the same manner as in Example 1 to obtain a powder composed of a resin mixture. The moisture content in the powder at this time was 1.3%. Further, in the same manner as in Example 1, powder coating was performed on the iron plate and pipe using the powder by the flow dipping method, and the impact resistance and hardness of the coating film were measured using the powder-coated iron plate and pipe. (Pencil hardness) / Coating film uniformity / Cleaning agent resistance was evaluated. The evaluation results are shown in Table 1.

  The resin (B) having an affinity for EVOH (A) is a core-shell polymer particle (B6) in which the glass transition temperature of the core component is −10 ° C. or lower and the glass transition temperature of the shell component is 30 ° C. or higher. Blended pellets were obtained in the same manner as in Example 1 except that Paraloid EXL2314 (carboxylic acid-modified acrylic core-shell polymer) manufactured by Kureha Chemical Co., Ltd. was used. MFR (measured under a load of 2160 g at 190 ° C.) of the obtained blend pellet was 28 g / 10 minutes. This blend pellet was pulverized in the same manner as in Example 1 and blended with inorganic fine particles (E) to obtain a powder. The water content in the powder at this time was 1.0%. Further, a powder was produced in the same manner as in Example 1, and powder coating was performed on the iron plate and pipe by the fluidized dipping method using this powder, and impact resistance was obtained using the powder-coated iron plate and pipe. -The hardness of the coating film (pencil hardness), the uniformity of the coating film, and the detergent resistance were evaluated. The evaluation results are shown in Table 1.

  As a resin (B) having an affinity for EVOH (A), Tosoh Corporation is an ethylene-vinyl acetate copolymer saponified product (B7) having an ethylene content of 70 to 95 mol% and a saponification degree of 85 mol% or more. Blend pellets were obtained in the same manner as in Example 1 except that Mersen H6960 (ethylene content: 90 mol%, saponification degree: 90 mol% or more) was used. The MFR (measured under a load of 2160 g at 190 ° C.) of the obtained blend pellet was 32 g / 10 minutes. This blend pellet was pulverized in the same manner as in Example 1 and blended with inorganic fine particles (E) to obtain a powder. The moisture content in the powder at this time was 1.1%. Further, a powder was produced in the same manner as in Example 1, and powder coating was performed on the iron plate and pipe by the fluidized dipping method using this powder, and impact resistance was obtained using the powder-coated iron plate and pipe. -The hardness of the coating film (pencil hardness), the uniformity of the coating film, and the detergent resistance were evaluated. The evaluation results are shown in Table 1.

  At the time of preparing the blend pellets of the resin mixture in Example 5, the addition amount of Irganox 1098 as the antioxidant (C) is 0.2 parts, and the addition amount of Irgaphos 168 as the phosphorus thermal stabilizer (D) is 0. A blended pellet was obtained in the same manner as in Example 5 except that it was changed to a part. MFR (measured under a load of 2160 g at 190 ° C.) of the obtained blend pellet was 27 g / 10 min. This blend pellet was pulverized in the same manner as in Example 1 and blended with inorganic fine particles (E) to obtain a powder. The moisture content in the powder at this time was 1.1%. Further, a powder was produced in the same manner as in Example 5, and powder coating was performed on the iron plate and pipe by the fluidized dipping method using this powder. Impact resistance was achieved using the powder-coated iron plate and pipe. -The hardness of the coating film (pencil hardness), the uniformity of the coating film, and the detergent resistance were evaluated. The evaluation results are shown in Table 1.

  A powder was obtained in the same manner as in Example 1 except that the fine powder (E) was not blended with the powder obtained by pulverizing the blend pellet of the resin mixture obtained in Example 1. The moisture content in the powder at this time was 0.9%. Further, a powder was produced in the same manner as in Example 1, and powder coating was performed on the iron plate and pipe by the fluidized dipping method using this powder, and impact resistance was obtained using the powder-coated iron plate and pipe. -The hardness of the coating film (pencil hardness), the uniformity of the coating film, and the detergent resistance were evaluated. The evaluation results are shown in Table 1.

Synthesis example 2
In Synthesis Example 1, as raw materials charged in the polymerization reaction vessel, in addition to 83.1 kg of vinyl acetate and 8.4 kg of methanol, 24.1 g of vinyltrimethoxysilane was added to the reaction vessel, and the same procedure as in Synthesis Example 1 was repeated. EVOH resin pellets modified with trimethoxysilane were obtained. In this EVOH pellet, the acetic acid content was 308 ppm, the calcium salt content was 70 ppm in terms of metal element, the potassium salt content was 35 ppm in terms of metal element, and the phosphate compound content was 51 ppm in terms of phosphate group. . Further, the MFR (measured under a load of 2160 g at 190 ° C.) of the obtained EVOH resin pellets was 10 g / 10 minutes.

  A powder was obtained in the same manner as in Example 5 except that the above modified EVOH was used as EVOH (A). The water content in the resin mixture powder at this time was 0.9%. Further, a powder was produced in the same manner as in Example 5, and powder coating was performed on the iron plate and pipe by the fluidized dipping method using this powder. Impact resistance was achieved using the powder-coated iron plate and pipe. -The hardness of the coating film (pencil hardness), the uniformity of the coating film, and the detergent resistance were evaluated. The evaluation results are shown in Table 1.

Comparative Example 1
Example 1 Except that 100 parts of the dry EVOH pellet obtained in Synthesis Example 1 is not added during the production of the blend pellet of the resin mixture in Example 1, and the resin (B) having affinity with EVOH (A) is not added. In the same manner, a blend pellet was obtained. The MFR (measured under a load of 2160 g at 190 ° C.) of the obtained blend pellet was 30 g / 10 minutes. This blend pellet was pulverized in the same manner as in Example 1 and blended with inorganic fine particles (E) to obtain a powder. The water content in the resin mixture powder at this time was 1.3%. Further, a powder was produced in the same manner as in Example 1, and powder coating was performed on the iron plate and pipe by the fluidized dipping method using this powder, and impact resistance was obtained using the powder-coated iron plate and pipe. -The hardness of the coating film (pencil hardness), the uniformity of the coating film, and the detergent resistance were evaluated. The evaluation results are shown in Table 1.

Comparative Example 2
Blend pellets were obtained in the same manner as in Example 2 except that the antioxidant (C) and the phosphorous heat stabilizer (D) were not added during the production of the blend pellets of the resin mixture in Example 2. The blend pellet obtained had an MFR (measured at 190 ° C. under a load of 2160 g) of 21 g / 10 min. This blend pellet was pulverized in the same manner as in Example 1 and blended with inorganic fine particles (E) to obtain a powder. The water content in the resin mixture powder at this time was 1.1%. Further, a powder was produced in the same manner as in Example 1, and powder coating was performed on the iron plate and pipe by the fluidized dipping method using this powder, and impact resistance was obtained using the powder-coated iron plate and pipe. -The hardness of the coating film (pencil hardness), the uniformity of the coating film, and the detergent resistance were evaluated. The evaluation results are shown in Table 1.

Comparative Example 3
Nippon Polyethylene Co., Ltd. Novatec LC600A, which is a polyolefin having no functional group capable of reacting with a hydroxyl group, instead of polyolefin (B1) having a functional group capable of reacting with a hydroxyl group at the time of preparing a blend pellet of the resin mixture in Example 1 Blend pellets were obtained in the same manner as in Example 1 except that they were used. MFR (measured under a load of 2160 g at 190 ° C.) of the obtained blend pellet was 28 g / 10 minutes. This blend pellet was pulverized in the same manner as in Example 1 and blended with inorganic fine particles (E) to obtain a powder. The water content in the resin mixture powder at this time was 1.0%. Further, a powder was produced in the same manner as in Example 1, and powder coating was performed on the iron plate and pipe by the fluidized dipping method using this powder, and impact resistance was obtained using the powder-coated iron plate and pipe. -The hardness of the coating film (pencil hardness), the uniformity of the coating film, and the detergent resistance were evaluated. The evaluation results are shown in Table 1.

Comparative Example 4
A block comprising an aromatic vinyl polymer block having a functional group capable of reacting with a hydroxyl group and a hydrogenated conjugated diene polymer block at the time of preparation of blend pellets of the resin mixture in Example 2 at an EVOH (A) addition amount of 30 parts A blended pellet was obtained in the same manner as in Example 2 except that the amount of Tuftec M1962 manufactured by Asahi Kasei Corporation, which is a copolymer (B2), was changed to 70 parts. The MFR (measured under a load of 2160 g at 190 ° C.) of the obtained blend pellet was 20 g / 10 minutes. This blend pellet was pulverized in the same manner as in Example 1 and blended with inorganic fine particles (E) to obtain a powder. The water content in the resin mixture powder at this time was 1.0%. Further, in the same manner as in Example 1, a powder was produced in the same manner as in Example 1, and using this powder, powder coating was performed on an iron plate and a pipe by a fluidized dipping method. Using pipes, impact resistance, coating film hardness (pencil hardness), coating film uniformity, and detergent resistance were evaluated. The evaluation results are shown in Table 1.

  The powder coatings of the present invention of Examples 1 to 11 exhibit good impact resistance of coating film, uniformity of coating film, and detergent resistance when powder coated on a substrate, and the characteristics of EVOH resin The good surface hardness is generally maintained. In Example 6 in which the amount of the resin (B) having affinity was large, the surface hardness was slightly inferior, but was within an allowable range. Further, in Example 9 which does not contain the phosphorus-based heat stabilizer (D), the resistance to the detergent was slightly inferior, but was within an allowable range. In Example 10 not containing the inorganic fine particles (E), the impact resistance and the uniformity of the coating film were slightly inferior, but were within the allowable range.

  On the other hand, when the powder of the comparative example 1 which does not contain resin (B) which has affinity with EVOH (A) is used as a powder coating material, and resin which does not have affinity with EVOH (A) When the powder of Comparative Example 3 was used as a powder coating, no sufficient impact resistance could be obtained.

  Further, in Comparative Example 2 in which the resin mixture powder not containing the antioxidant (C) and the phosphorus-based heat stabilizer (D) is used as a powder coating, the powder coating is powder-coated on a base material. The coating film obtained was poor in detergent resistance and was unsuitable for drain pipe painting.

  Further, in Comparative Example 4 in which the weight ratio A / B between EVOH (A) and the resin (B) having an affinity for EVOH (A) is larger than 40/60, the amount of (B) is increased. The characteristic good surface hardness was lost.

The multilayer structure in which the powder coating material of the present invention is applied to a base material such as metal is used for domestic wastewater and building / construction that are exposed to various disinfectants, bleaches, toilet cleaners, etc. containing chlorine compounds for a long time. Used for on-site drainage pipes.

Claims (10)

Resin composition comprising ethylene-vinyl alcohol copolymer (A), resin (B) having affinity with ethylene-vinyl alcohol copolymer (A), antioxidant (C), and phosphorus-based heat stabilizer A powder (P) comprising (D), wherein the weight ratio A / B of (A) to (B) in the powder (P) is 40/60 to 98/2, (A) And the weight ratio (A + B) / C to (C) is 100 / 0.005 to 100/20, and the sum of (A) and (B) and (C ) And the sum of (D) (A + B) / (C + D) is 100 / 0.005 to 100/20,
The ethylene-vinyl alcohol copolymer (A) is an ethylene-vinyl alcohol copolymer having an ethylene content of 2 to 60 mol% and a saponification degree of 85 mol% or more,
The resin (B) having an affinity for the ethylene-vinyl alcohol copolymer (A) comprises a carboxyl group, a carboxylic acid ester group, a carboxylic acid anhydride group, a carboxylic acid group, an ester bond, a urethane bond and an amide bond. Core-shell polymer particles in which the glass transition temperature of the thermoplastic resin or core component having a functional group capable of reacting with at least one hydroxyl group selected from the group is −10 ° C. or lower and the glass transition temperature of the shell component is 30 ° C. or higher (B6) and at least one resin selected from the group consisting of ethylene-vinyl acetate copolymer saponified product (B7) having an ethylene content of 70 to 95 mol% and a saponification degree of 85 mol% or more,
Powder in which the antioxidant (C) is at least one antioxidant selected from the group consisting of phenolic antioxidants, hindered phenolic antioxidants, and vitamin E antioxidants.   Polyolefin (B1) having a functional group capable of reacting with a hydroxyl group, a resin (B) having an affinity for the ethylene-vinyl alcohol copolymer (A), an aromatic vinyl polymer having a functional group capable of reacting with a hydroxyl group A block copolymer (B2) comprising a block and a hydrogenated conjugated diene polymer block; a polyester (B3) having a glass transition temperature of −150 to 25 ° C. and a crystal melting heat of 30 J / g or less; and a thermoplastic polyurethane (B4) The powder according to claim 1, which is at least one thermoplastic resin selected from the group consisting of a polyamide resin (B5).   The block copolymer (B2) comprising an aromatic vinyl polymer block and a hydrogenated conjugated diene polymer block has, as a functional group capable of reacting with a hydroxyl group, a carboxyl group, a carboxylic acid ester group, a carboxylic acid anhydride group, and a carboxylic acid group. The powder according to claim 2, which has 10 to 1000 μeq / g of at least one functional group selected from the group consisting of acid bases. The powder according to any one of claims 1 to 3 , wherein the powder (P) further contains inorganic fine particles (E). The powder according to claim 4 , wherein the inorganic fine particles (E) are silica particles or alumina particles having an average primary particle diameter of 1 to 100 nm. The powder according to any one of claims 1 to 5 , wherein the particle diameter is 22 to 850 µm. The powder coating material consisting of the powder of any one of Claims 1-6 . The multilayer structure formed by apply | coating the powder coating material of Claim 7 to a base material. A multilayer structure excellent in detergent resistance obtained by applying the powder paint according to claim 7 to a substrate. A drainage pipe excellent in detergent resistance obtained by applying the powder paint according to claim 7 to a substrate.