KR20140019387A - Soft feel powder coating having anodized look - Google Patents

Abstract

When cured, a powder coating composition is provided having an anodized look. This powder coating composition comprises the following components
a. Binder resin,
b. Solvent soluble dyes,
c. Matting effect compounds,
d. Polymer A consisting of particles having an average particle size of 0.1 μm to 60 μm and a Tg of −60 ° C. to 75 ° C., and
e. Pigments or dyes that are insoluble in the solvent, based on the total weight of the powder coating composition, of less than 10% by weight.
Provides a substrate having an ADE-index of at least 3 and having an anodized appearance.

Description

Soft Peel Powder Coating with Anodized Appearance {SOFT FEEL POWDER COATING HAVING ANODIZED LOOK}

The present invention relates to powder coating compositions which, when cured, provide a special effect coating, ie a soft feel coating with an anodized look.

Powder coating compositions are generally solid compositions comprising a solid film-forming resin usually with one or more pigments and optionally one or more performance additives such as plasticizers, stabilizers, flow aids and extenders. The resins usually thermoset, for example, incorporate a binder resin and a corresponding crosslinker (which may itself be another binder resin). Generally, the resin has a T _g , softening point or melting point above 30 ° C.

Typically, the preparation of the powder coating comprises melt-mixing the components of the composition. Melt-mixing comprises mixing, in a continuous compounder, the dry ingredients at high speed, high strength, and then heating the mixture at an elevated temperature below the softening point above the resin's softening point to produce a molten mixture. do. The mixer preferably comprises a single screw or twin screw extruder which improves the dispersibility of the other components in the resin as the resin melts. The molten mixture is extruded, typically rolled into sheet form, cooled to solidify the mixture and then crushed (crushed).

Then, after such processing, generally, such as grinding, classifying, sifting, screening, cyclone separation, sieving, and filtering Particle sizing and separation operations are performed, which precedes the application of the powder to the substrate and the heating of the powder to melt and melt the particles and cure the coating. Main methods of applying powder coatings include fluidized bed and electrostatic fluidized bed processes, and electrostatic spray processes in which powder coated particles are electrostatically charged by a spray gun and directed onto an earthed substrate.

Anodizing is an electrochemical process that forms a protective layer of aluminum oxide on the surface of an aluminum sheet. This layer can be colored by dyeing the electrochemical bath. Due to anodizing, aluminum has a deeper and richer metallic appearance than is possible with organic coatings. The anodized surface is translucent so that the underlying base metal remains visible even after treatment.

This anodized appearance is desirable for various applications and for various substrates in addition to aluminum substrates.

The anodized appearance can be measured objectively by measuring the reflectance in a direction perpendicular to the longitudinal direction of the observed texture. For each measurement, the L, a, and b values can be recorded, and the color difference in the direction perpendicular to the longitudinal direction of the texture can be calculated with a standard color difference equation. When measuring the reflectance at the flop angle (110 ° from specular reflection) for a surface with an anodized appearance, it is found that (length of texture-right angle) ΔE is greater than 3. For non-anodized surfaces, at low or high gloss, (length of texture-right angles) ΔE is found to be less than 2.

In the present invention, the surface with an anodized appearance is a surface with an ADE-index greater than 3, which is defined as ΔE (length of texture-right angle) measured according to the method described above.

At the present time, without the use of well-known electrochemical processes, there are no coatings (both solvent-based and powder coatings) available for forming soft peel coatings with anodized appearance.

GB 1363741 discloses various powder coating compositions. These powder coating compositions will not provide an anodized appearance upon application and curing to the substrate.

US6800334 discloses various powder coating compositions. These powder coating compositions will not provide an anodized appearance upon application and curing to the substrate.

EP 1347021 discloses various powder coating compositions. These powder coating compositions will not provide an anodized appearance upon application and curing to the substrate.

In JP 63243176 various powder coating compositions are disclosed. These powder coating compositions will not provide an anodized appearance upon application and curing to the substrate.

WO 2007/060070 discloses various powder coating compositions. These powder coating compositions will not provide an anodized appearance upon application and curing to the substrate.

In JP 2006185525 various powder coating compositions are disclosed. These powder coating compositions will not provide an anodized appearance upon application and curing to the substrate.

WO00 / 01774 discloses powder coating compositions with reduced gloss and a textured metal finish. These powder coating compositions will not provide an anodized appearance upon application and curing to the substrate. In addition, no mention is made of how this document can obtain a coating with an anodized appearance. This document also does not mention powder coatings with so-called "soft peels."

It has been found that soft fill substrates with an anodized appearance can be obtained when the powder coating is applied and cured rather than comprising polymer A and a clear pigment and substantially free of any opaque pigment. None of the foregoing documents discloses such a combination, and the teaching or suggestion that the combination may also provide a powder coating that can be used to form such a soft fill and anodized appearance on a substrate. does not exist.

Therefore,

a. Binder resin,

b. Solvent soluble dyes,

c. Matting effect compounds,

d. Polymer A consisting of particles having an average particle size of 0.1 μm to 60 μm and a T _g of −60 ° C. to 75 ° C., and

e. A powder coating composition obtainable by processing a mixture comprising a pigment or dye insoluble in a solvent, based on the total weight of the powder coating composition, of less than 10% by weight.

In the context of this description, the T _g of the compound is measured according to ASTM D3418.

In one embodiment of the invention, the solvent soluble dye is a metal complex dye.

In another embodiment of the present invention, the powder coating composition comprises an agent that increases the solubility of the dye in the binder resin.

In another embodiment of the invention, the agent which increases the solubility of the dye in the binder resin comprises isocyanate groups.

In another embodiment of the present invention, the agent for increasing the solubility of the dye in the binder resin comprises a caprolactam blocking group.

Another embodiment of the present invention,

a. Binder resin,

b. Solvent soluble dyes,

c. Matting effect compound,

d. Polymer A consisting of particles having an average particle size of 0.1 μm to 60 μm and a Tg of −60 ° C. to 75 ° C., and

e. Based on the total weight of the powder coating composition, a powder coating composition obtainable by processing a mixture comprising less than 10% by weight of a pigment or dye insoluble in a solvent is applied to the substrate, the substrate is heated, and the powder A method of making a substrate having an anodized appearance, consisting of curing the coating.

The resins and crosslinking systems in the powder composition are not intended to limit the features of the present invention. That is, resins suitable for inclusion in powder coating premixes include both thermoplastic and thermoset base resins.

When used in powder coating, the thermoplastic resin should melt in a few minutes and flow out into the thin film without significant decomposition at a stoving temperature of 120 ° C to 300 ° C. Accordingly, suitable thermoplastics for use in the practice of the present invention include polyamides, polyesters, cellulose esters, polyethylene, polypropylene, poly (vinyl chloride) [PVC], poly (vinylidene fluoride) [PVF2], polyphenyl Sulfones and poly (tetrafluoroethylene) [PTFE], particularly preferably polyphenylsulfone and PTFE. Suitable thermoplastic resins are all readily available on the market.

Thermosetting resins suitable for the present invention include epoxy resins, polyurethanes, silicones, crystalline resins, polyesters (including unsaturated polyesters), acrylics, and hybrids such as epoxy-acryl, polyester-acrylic, and epoxy-polyesters. Include. The glass transition temperature (T _g ) of these resins should be high enough that the particles will not fuse or sinter with each other at the temperatures that will be encountered during transport and storage. Preferably, the range of T _g is 45 ° C. to 120 ° C., and more preferably T _g is greater than 55 ° C. in this range.

Powder coatings according to the invention are obtainable by processing a mixture of various components. Such processing may be a method known to those skilled in the art for preparing powder coating compositions.

Methods for preparing powder coating compositions known to those skilled in the art are described, for example, in "Powder Coatings Chemistry and Technolog" by P.G. Chapter 5 (Technology of Production of Powder Coatings) of de Lange, Hannover, Vincentz Network, 2004. The method comprises the following steps: weighing the raw materials-premixing-hot melt mixing-cooling-granulating-fine grinding-sorting-packaging.

However, other processes may be used, such as the "VAMP" (VEDOC Advanced Manufacturing Process) process or CPCSP (Continuous Powder Coating Spray Process) where the raw materials are mixed in supercritical carbon dioxide.

Epoxy resin

Suitable epoxy resins are those containing aliphatic or aromatic backbones with oxirane functionality, for example diglycidyl ether condensation by reaction of epichlorohydrin with bisphenols such as bisphenol A and bisphenol F in the presence of an alkali catalyst. polymer; And glycidyl ethers of phenolic novolac resins synthesized by reacting phenolic novolac resins with epichlorohydrin in the presence of sodium hydroxide as catalyst.

Generally, epoxy resins have an epoxide equivalent weight (EEW) of 600 to 2000; Hydroxyl equivalent weight is from 300 to 400; The melt viscosity should range from 200 centipoise (cps) to 2000 cps, preferably 300 cps to 1000 cps at 150 ° C. The melt viscosity of these resins is low so that the resins can be extruded at temperatures below 200 ° C.

Commercially available epoxy resins preferred for the purposes of the present invention are bisphenols sold under the trade names ARALDITE ^® GT-7004, GT-7071, GT-7072, GT-6259 (Huntsman LLC), EPON ^® 1001 and 2042 (Shell Chemicals, Inc.). A epoxy.

Depending on the process and required properties, a wide variety of curing agents for epoxy resins are available. Dicyandiamide, modified and substituted dicyandiamides, solid dicarboxylic acids and their anhydrides are examples of agents that may be used for curing the epoxy resins. In the formulation of the epoxy resin powder as well as the formulation of other resin powder in the present invention, a solid form of the curing agent is preferred for convenience.

Silicone resin

Silicone resin used for this invention is solid at room temperature; T _g is greater than 55 ° C., preferably greater than 60 ° C .; The viscosity should be about 500 cps to about 10,000 cps, preferably 2000 cps to 5000 cps at 150 ° C.

Silicone resins suitable for use in the present invention include, inter alia, US Pat. No. 3,170,890; 4,879,344; 3,585,065; And 4,107,148, the entirety of which is incorporated herein by reference. Examples of suitable, commercially available silicone resins are phenylsilicone SY-430 and methylsilicone MK (both from Wacker Silicone, USA) and methylphenylsilicone 6-2230 (Dow Corning).

Hydroxy functional polyester resin

Suitable hydroxy functional polyesters for use in the methods of the invention are hydroxyl predominantly in functional groups, preferably i) having a hydroxyl number in the range of about 25 to about 50; ii) the acid value is no greater than 15, preferably in the range of about 1 to 2; iii) T _g must be greater than 50 ° C.

Hydroxy functional polyesters that meet these conditions are commercially available as RUCOTE® 107, CARGILL® 3000/3016, and CRYLCOAT® 3109. However, likewise, such polyesters can be formed as condensation products of polyhydric carboxylic acids and polyhydric alcohols. As such, carboxylic acids useful in the preparation of such polyester resins are phthalic acid, tetrahydrophthalic acid and hexahydrophthalic acid and their anhydrides, succinic acid, adipic acid, sebacic acid, terephthalic acid and isophthalic acid, 1,3-cyclohexane-di Carboxylic acids and 1,4-cyclohexane-dicarboxylic acids, and trimellitic anhydride, one or more of esters of these acids. Suitable difunctional alcohols also include isomers of ethylene glycol, diethylene glycol, propylene glycol, 1,2 and 1,3 propylene glycol and trimethylene glycol, and suitable dihydric alcohols include hexanediol, 1,3 -Butanediol, 1,2-butanediol, and 1,4-butanediol, neopentyl glycol, 2-butyl-2-ethyl-1,3-propanediol, 2-methyl-1,3- Propanediol, 1,4-cyclohexanediol, trimethylolpropane, and mixtures thereof. Those skilled in the art will be aware of these acids and alcohols significantly and will know how to perform condensation of acids with alcohols.

The hydroxyl-functional polyesters can be cured through hydroxyl groups with aliphatic and aromatic isocyanates, and aminoplasts. Isocyanate curing is technically polyester but when cured forms a resin described as polyurethane. Aminoplasts are oligomers which are reaction products of aldehydes, in particular the amino- or amino-group-containing components exemplified by formaldehyde with melamine, urea, dicyandiamide, and benzoguanamine. In many cases, it is preferable to use precursors of aminoplasts, such as hexamethylol melamine, dimethylol urea, and their etherified forms, ie modified forms with alkanols having 1 to 4 carbon atoms. Hexamethoxymethyl melamine and tetramethoxy glycoluril are illustrative of such etherified forms. Especially preferred is CYMEL®, an amino crosslinker available from American Cyanamid. Accordingly, a wide variety of commercially available aminoplasts and their precursors can be used in combination with the hydroxyl functional polyesters of the present invention.

The aminoplast curing agent is typically provided in an amount sufficient to react with at least half of the hydroxyl groups of the polyester, ie at least half the stoichiometric equivalent of the hydroxy functional group. One skilled in the art will select the correct stoichiometric ratio and catalyst concentration to achieve the desired coating performance. Preferably, the amount of crosslinking agent is sufficient to react substantially completely with all of the hydroxy functional groups of the polyester, and the crosslinking agent having nitrogen crosslinking functionality is about 2 to about 12 equivalents of the nitrogen crosslinking functional group per equivalent of the hydroxy functional group of the polyester. Is provided.

Acid curing may be used when curing of polyesters with aminoplast resins is altered by lowering the required temperature, increasing the reaction rate, or both. If slowing down at ambient storage temperatures is desired, the acidic catalyst can be blocked with amines. Volatile amines that can escape from the cured film when the catalyst is not blocked by heat are suitable for the purposes of the present invention. For the purposes of the present invention, it is particularly preferred to slow overall curing of the composition. NACURE® 1557, an amine-blocked dinonylnaphthalenesulfonic acid available from King Industries, is an example of a blocked acid catalyst suitable for use in aminoplast curing of the powder coating compositions of the present invention.

Diisocyanates cure hydroxy functional polyester resins by forming urethane linkages between polymer chains at the hydroxyl group sites. Common aliphatic diisocyanates are exemplified by hexamethylene diisocyanate (HDI), diisocyanato dicyclohexylmethane (commercially available as DESMODUR W ^® by Mlles Chemical) and isophorone diisocyanate (IPDI). Toluene diisocyanate (TDI) is an example of a suitable aromatic diisocyanate. The low temperature reactivity of the free diisocyanates can be attributed to phenols, cresols, isononylphenols, amides such as epsilon-caprolactam, oximes such as methyl-ethyl ketoxime and butanoneoxime, diethylmalonate, isopropylidene malonate and It can be reduced by adding a blocking agent selected from active methylene group-containing compounds such as acetoacetate, and sodium bisulfite. Examples of blocked diisocyanates include caprolactam blocked isophorone diisocyanate, and caprolactam blocked hexamethylene diisocyanate. Examples of commercially available curing agents of this type are the 24-2400, 24-2430, and 24-2450 products sold under the trade name CARGILL. Another group of blocked curing agents is uretdione, which may be described as blocked internally.

Carboxy Functional Polyester Resin

Carboxyl-functional polyesters are also suitable for the purposes of the present invention. They can be prepared from the same polyfunctional acids and glycols as the hydroxyl-functional polyesters, but the acid is used in excess. The acid value is about 10 to about 100. Suitable commercially available products include CRYLCOAT® 430, 3010 and 7617 (available from UCB); URALAC® 3400 and 3900; EL6500 or EL6700 or EL8800 available from Chan Sieh Enterprises Fast, and curing of these carboxyl functional polyesters can be carried out using polyepoxide curing agents such as triglycidyl isocyanurate (TGIC).

Other alternative curing agents for TGIC include Primid such as the hydroxyalkylamides Primid XL552 and QM1260 available from EMS-Primid; Araldite PT910 glycidyl ester available from Ciba Geigy; And Uranox available from DSM.

Unsaturated polyesters suitable for use in the practice of the present invention include organic difunctional or polyfunctional acids and ethylenically unsaturated reaction products of difunctional or polyfunctional alcohols. Typically the acid is unsaturated. Such polyester resins typically work best in combination with a copolymerizable second resin such as diallyl phthalate. Initiators may need to be included.

Acrylic resin

Preferred acrylic resins for powder coatings are copolymers of alkyl acrylates and / or methacrylates with glycidyl-methacrylates and / or acrylates and olefinic monomers such as styrene. Glycidyl-functional acrylic resins are manufactured from Mitsui Toatsu Chemicals, Inc., in which carboxy-terminated polymers can be used as crosslinking agents. Is commercially available as ALMATEX®. Hydroxyalkyl acrylate and methacrylate copolymers are also suitable for the present invention.

Hybrid resin systems

Hybrid resin systems such as epoxy-acrylic and polyester-acrylic mixtures are also suitable for the present invention. However, when applying such a system, it is preferably a polyester-epoxy hybrid. As is known in the art, polyester-epoxy hybrids include both epoxy resins and carboxyl terminated polyester resins, and may also include catalysts to cause curing reactions. Typically, the equivalent weight of the acidic polyester is 600 to 4000, and the equivalent weight of the epoxy resin is 400 to 1100. Catalysts for epoxy-acid reactions include quaternary ammonium salts, quaternary phosphonium salts, phosphines, amines, imidazoles and metal salts. Amphoteric catalysts such as zinc oxide (ZnO ₂ ) exert an effect at 1 to 5 parts by weight per 100 parts by weight of resin, improving the curing rate and physical properties of the product.

Solvent soluble dyes

Powder coating compositions according to the invention also comprise solvent soluble dyes. Such dyes usually exhibit good solubility in solvents and ester solvents such as alcohols, ketones, and glycol ethers.

In one embodiment of the invention, the solvent soluble dye is a metal complex dye. Metal-complex dyes are also known as pre-metalized dyes. Metal complex dyes can be applied to dye both natural and synthetic fibers such as polyamide fibers and wool. Chemically speaking, metal complex dyes can be broadly classified into two classes. In 1: 1 metal-complexes, one dye molecule coordinates with a single metal atom. In a 1: 2 metal complex, one metal atom coordinates with two dye molecules. The dye molecule is typically a monooazo structure which may contain additional groups such as hydroxyl groups, carboxyl groups or amino groups. They can form strong coordination complexes with transition metal ions such as nickel, chromium, cobalt and copper.

In one embodiment of the invention, the solvent soluble dye is a 1: 2 metal complex dye.

Examples of solvent soluble dyes that can be used in the coating compositions according to the invention include metal complex dyes, fluorescent dyes, polymer soluble dyes, and polysynthren dyes. An example of a dye that may be used in the coating composition of the invention is a Savinyl®-type dye supplied by Clariant.

Such dyes have been found to exhibit good solubility in binder resins, especially when using polyester binder resins.

It has been found that when using resins or mixtures of resins with dyes of secondary or poor solubility, the solubility can be increased by using compounds with isocyanate groups. In other embodiments, it has been found that solubility can be increased by using compounds with caprolactam groups. It is also possible to use compounds having both isocyanate functionalities and caprolactam functional groups, for example compounds having isocyanate groups blocked with ε-caprolactam. Examples of compounds that can be used to improve the solubility of dyes in binder resins include Vestagon® B1530 (ε-caprolactam blocked polyisocyanate ex. Degussa) and Vestagon® B1540 (blocked uretdione compound, ex Degussa) Included.

Matting effect compound

The coating composition according to the invention also comprises a matting effect compound. In combination with soluble dyes, the matting effect compound is an essential ingredient in obtaining a cured powder coating having an anodized appearance.

Within the framework of the present application, the matting effect compound is a compound that is added to the composition to obtain a matting effect. In the composition according to the invention, various types of matting effect compounds can be used as follows:

Waxes, or wax mixtures;

A second binder resin having a gel time different from the gel time of the binder resin already present in the composition;

Gloss reducing agents which react with binder resins;

A hardener with different reactive groups, said reactive groups exhibiting different reactivity with respect to the binder resin; And

-Large amounts of coarse filler.

Suitable waxes can be selected from the group consisting of polyamide waxes and polyethylene waxes. The wax can be modified such as micronised or PTFE-modified. Generally, the melting point of the wax is in the range of 100 ° C to 160 ° C.

An example of the use of the second binder resin is two different types of polyester resins, one type of polyester resin having a relatively short gel time and another type of polyester resin having a relatively long gel time. It can be found in the composition comprising.

One example of a gloss reducing agent that reacts with a binder resin when used in combination with a polyester binder resin is Synthacryl 700. Another example of such compounds when used in polyester / epoxy hybrid binder systems is T-325, a resin-based delustering agent.

When used in combination with epoxy resins, an example of a curing accelerator having different reactive groups is Vestagon B68.

A relatively large amount of coarse barium sulphate and calcium carbonate can be used to obtain a cured powder coating with a matte appearance.

Soft Peel (Co) polymer

The composition according to the invention comprises polymer A which provides a soft peel or soft touch effect, said soft peel polymer A consisting of particles having an average particle size of 0.1 μm to 60 μm and a T _g of −60 ° C. to 75 ° C. have. Optimal soft peel properties are observed when the T _g of the (co) polymer is less than 10 ° C., for example the range of T _g is −10 ° C. to −50 ° C.

In one embodiment, Polymer A is a vinyl ester of carbon monoxide, ethylene, and saturated carboxylic acid having 1 to 18 carbon atoms and methacrylate and alkyl acrylate having 1 to 10 carbon atoms in the alkyl group. Copolymers of unsaturated ester monomers. Typical vinyl ester softening monomers that can be used according to the present invention include vinyl acetate, vinyl propionate, vinyl 2-ethylhexate and vinyl neodecanoate. Typical alkyl acrylate and methacrylate softening monomers include methyl acrylate, isobutyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, ethyl methacrylate, isobutyl methacrylate, and isononyl Methacrylates. Mixtures of softening monomers can be used.

In one embodiment, the copolymer comprises 40 mol% to 80 mol% ethylene, 10 mol% to 60 mol% vinyl acetate, and 3 mol% to 30 mol% carbon monoxide. In these copolymers, vinyl acetate is a vinyl ester of saturated carboxylic acid having 1 to 18 carbon atoms, and other unsaturations such as alkyl acrylates and methacrylates having 1 to 10 carbon atoms in the alkyl group. It may be substituted with an ester softening monomer.

The copolymer can be prepared by passing a compressed mixture of ethylene, unsaturated ester monomer and carbon monoxide together with a free radical generating catalyst through an autoclave set at elevated temperatures and pressures of 155 ° C. to 225 ° C. and 140 MPa to 250 MPa, Meanwhile, the product polymer and unreacted monomer can be removed at the same rate. Under these conditions, about 10% by weight of the monomers fed are converted to the polymer. The manufacturing process is described in more detail in Hammer 3,780,140 and Brubaker 2,495,286.

Alternatively, in order to obtain a soft but less sticky (co) polymer, polymer A with a T _{g of} from -60 ° C to 75 ° C, preferably -10 ° C to 75 ° C, may be used as a (meth) acrylate monomer, vinyl monomer, Or reactive resins, which are t-butyl acrylate (t-BA) (co) polymers, 2-ethylhexyl (meth) acrylate (co) polymers, ethyl (meth) acrylate copolymers, sec-butyl ( Meth) acrylate (co) polymer, methyl acrylate (co) polymer, hexyl (meth) acrylate (co) polymer, isobutyl (meth) acrylate (co) polymer, benzyl (meth) acrylate (co) polymer , Isopropyl (meth) acrylate (co) polymer, decyl (meth) acrylate (co) polymer, dodecyl (meth) acrylate (co) polymer, n-butyl (meth) acrylate (co) polymer, C21 To C30 alkyl (meth) acrylate (co) polymers, vinyl propio Yttrium (co) polymers, urethane polymers, urea-formaldehyde resins, melamine resins, silicone-containing (meth) acrylate copolymers, airborne monomers or resins used to make polymers with (meth) acrylic monomers And copolymers prepared from resins and monomers used to make polymers with vinyl monomers.

The (co) polymer particles can be, for example, multi-stage (co) polymers having a layer structure or core-cell, such as a multilobal structure. The multistage (co) polymer may comprise a polymer core phase and one or more polymer cell phases, and may comprise a graded refractive index compositon. The core may be made from various vinyl monomers and may be a rubber or glassy polymer. The core may be a monomer such as a diolefin such as butadiene or isoprene; Vinyl aromatic monomers such as styrene or chlorostyrene; Vinyl esters such as vinyl acetate or vinyl benzoate; Methacrylonitrile; (Meth) acrylate esters such as methyl methacrylate, butyl methacrylate, phenyl methacrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, and benzyl acrylate; Vinyl chloride; And other monomers polymerizable by free-radical initiation.

 The (co) polymer particles may also comprise multistage polymers, ie having a rubbery core with a Tg of 20 ° C. or less or 10 ° C. or less. The rubbery core may comprise synthetic or natural rubber, preferably acrylic rubber. The acrylic rubber core comprises an alkyl acrylate copolymer, the alkyl group having 2 to 8 carbon atoms, preferably having t-BA or BA, and from 0 to 10% by weight based on the total weight of the core monomers Wt%, preferably up to about 5 wt%, or up to 1 wt%, or at least 0.05 wt% based on the total weight of at least one crosslinker, core monomer, from 0 wt% to 10 wt%, preferably 5 wt% Or at least 2.5% by weight, preferably at least 0.1% by weight, or at least 0.5% by weight of at least one graftlinker, and from 0% to 50% by weight, based on the total weight of the core monomers Copolymerizable vinyl monomers. At least one polymer cell surrounds the acrylic rubber. The cell (s) may comprise from 0% to 40% by weight of the multistage particles. Copolymerizable vinyl monomers or monomers are monovinyl monomers such as alkyl methacrylates and monovinyl arenes such as styrene, alkylstyrenes such as methyl styrene and ethyl styrene, other substituted vinylbenzenes (the above substituents do not interfere with polymerization) ), And vinyl polycyclic aromatic monomers. In one example, a preferred two-stage 5 μm average particle size copolymer comprises rubbery poly (BA) crosslinked with allyl methacrylate and has a rigid cell of poly methyl methacrylate (pMMA), the cell 20 wt%.

The (co) polymers may be prepared by any known aqueous polymerization process, with the result that the average particle size is 0.1 μm to 60 μm, preferably 0.5 μm to 20 μm, more preferably 0.5 μm to 10 μm. Particles are obtained. In another embodiment, the particles preferably have a narrow particle size distribution (PSD).

(Co) polymers with particles in the upper limit of the desired size range can be prepared by suspension polymerization techniques, but this requires particle sorting after polymerization. The (co) polymer particles also form emulsion (co) polymer or oligomer seed particles by aqueous emulsion polymerization of one or more monomers, which are then swelled with one or more monomer components, and the emulsion It can be prepared by polymerizing one or more monomers in the seed particles to obtain particles of the desired average diameter. The expansion and polymerization steps can be repeated until the particles have grown to the desired core or single stage (co) polymer size. When seed particles are prepared in advance, particles and compositions of various sizes suitable for use can be prepared using suitably sized expandable (co) polymer or oligomer seeds. Suitable emulsion polymerization processes for preparing the (co) polymer particles are mentioned in US20070218291.

In general, the (co) polymer particles are spray dried or lyophilized into a powder having an average particle size of 0.1 μm to 60 μm, preferably 0.5 μm to 20 μm, more preferably 0.8 μm to 5 μm. (Co) polymer particles having such particle size are suitable for the present invention.

If the average particle size of the soft peel (co) polymers is less than 0.1 μm, it will be difficult to achieve good mixing and dispersion of the (co) polymers in the coating powder composition during extrusion, resulting in an uneven matte powder coating after curing. Will be formed. If the average particle size of the (co) polymer is more than 60 μm, there will be a seed problem on the powder coating surface, or especially if the applied coating thickness is less than 70 μm to 80 μm, it will not be possible to form a smooth powder coating during application. Will be.

The amount of soft peel polymer A in the powder composition of the present invention varies from 0.1% to 40% by weight based on the total weight of the composition. If the content of the (co) polymer is less than 0.1% by weight, the coating will not reduce gloss or obtain a soft touch feeling.

In one embodiment of the powder composition of the present invention, a low content of (co) polymer in the coating powder composition of 0.5% to 19% by weight, preferably 0.5% to 10% by weight, is soft and soft to the coating formed. It is not only sufficient to provide a low gloss soft touch surface but also to provide improved mechanical properties such as good flexibility and less coating cracking in the Mandrel Bend test and the 180 ° bend test.

In another embodiment of the powder composition of the present invention, the addition of the (co) polymer in an intermediate amount of from 19% to 40% by weight of the coating powder composition results in the resulting coated surface achieving a textured soft touch feeling.

The content of the soft peel (co) polymer should not exceed 40% by weight of the coating powder composition. High content soft peel (co) polymers result in textured textured surfaces with poor mechanical properties due to insufficient wetting and poor film formation of the (co) polymer with resins.

Examples of suitable compounds that can be used as soft peel (co) -polymers include Eosares Flex 7002 (ex. Kimya Chemicals), Elvaloy 741 and Elvaloy 742 (ex DuPont de Nemours), and poly (BA) by Dow Chemical ( Particle size, including various crosslinked and non-crosslinked core-cell polymers made from 80% by weight rubbery core of crosslinked with allyl methacrylate and 20% by weight of hard cell of poly methyl methacrylate (pMMA) The range is 0.8 μm to 5 μm.

In addition to the resin system, the dye, and the matting effect compound described above, the powder coating composition may include other components commonly known in the art. These may include fillers, flow control agents, degassing agents, and antiblocking agents.

The powder coating composition according to the invention comprises less than 10% by weight of pigments or dyes which are insoluble in the solvent, based on the total weight of the powder coating composition.

In one embodiment, the powder coating composition according to the present invention is substantially free of any opaque pigments, but may comprise small amounts of transparent pigments. Large amounts of pigments can ruin the anodized / translucent appearance of the coating. In the context of the present invention, substantially free means that the composition comprises less than 0.5% by weight of any opaque pigment, more particularly less than 0.1% by weight of any opaque pigment. In one embodiment, the composition does not include any opaque pigments, but may comprise small amounts of transparent pigments.

Examples of opaque pigments include inorganic pigments such as titanium dioxide, red and yellow iron oxides, chromium pigments and carbon black.

Further additives suitable for powder coating compositions include adhesion promoters; Light stabilizers and UV absorbers; Flow and surface conditioning additives; Gloss-modifying additives; Cratering agents; Curing agent; Texturizing agents; Surfactants; Wetting agents; Antioxidants (particularly phosphites, hindered phenols and propionates); Biocides; And organic plasticizers.

Fillers may be used to reduce costs and / or to enhance or modify the performance and appearance of the coating. Fillers comprising glass particles, glass fibers, metal fibers, metal flakes and particles of mica or calcium metasilicate may be included in the powder coating compositions of the present invention. Inorganic sulfates such as barite, carbonates such as chalk, and silicates such as talc are commonly used.

A metallic material comprising zinc rich anticorrosive particles may be added to the powder coating composition to impart corrosion resistance to the underlying substrate.

Flow control agents may be present in the powder coating composition in an amount of up to 3% by weight, based on the weight of the composition. Such flow control agents, which help to increase the melt flow properties of the composition and eliminate surface defects, typically include acrylic and fluoropolymers. (All commercially available from Estron Chemical Inc. capture of Calvert City, KY material) Examples of commercially available flow control ^{agents, Resiflow ® P-67, Resiflow} ® P-200 and Clearflow ^®; BYK ^® 361 and BYK ^® 300 by BYK Chemie (Wallingford, CONN); Mondaflow ^® 2000 from Monsanto (St. Louis, MO); And Acranal 4F from BASF.

Degassing agents are also used in powder coating compositions of the present invention in amounts of 0.1% to 5% by weight, based on the weight of the composition. Such degassing agents promote the release of gases during the curing process. Examples of commercially available degassing agents include Benzoin available from Well Worth Medicines; And Uraflow ^® B, available from GCA Chemical Corporation (Brandenton, FLA).

The powder coating composition may also comprise an antiblocking agent (dry-flow additive) in an amount of 0.05% to 1.0% by weight based on the total weight of the composition. Examples of such additives include fumed silica, precipitated silica, fumed alumina, clay, talc and mixtures thereof.

Typical powder coating compositions according to the present invention are

40% to 95% by weight of binder resin or mixture of binder resins;

0.2 wt% to 2 wt% of a solvent soluble dye;

0.2% to 60% by weight of the matting effect compound;

0 wt% to 8 wt% of a curing agent;

0% to 25% by weight of an agent which increases the solubility of the dye;

0.1 to 40 weight percent of polymer A; And

Other components from 0.2% to 5% by weight,

The weight percent is calculated based on the total weight of the powder coating composition and the total sum of all components of the powder coating composition is 100 weight percent.

Typical powder coating compositions according to the invention, based on polyester binder resins, are

40 wt% to 60 wt% of a first polyester resin;

40 wt% to 60 wt% of the second polyester resin having a different gel time from the first polyester resin and acting as a matting effect compound;

2 wt% to 8 wt% of a curing agent;

0.2 wt% to 2 wt% of a solvent soluble dye;

0.5 to 19 weight percent of polymer A; And

Other components from 0.2% to 5% by weight,

The weight percent is calculated based on the total weight of the powder coating composition and the total sum of all components of the powder coating composition is 100 weight percent.

Typical powder coating compositions according to the invention, based on a hybrid binder resin, are

30 to 50 weight percent of polyester resin;

30 wt% to 50 wt% of an epoxy resin;

0.2 wt% to 2 wt% of a solvent soluble dye;

0.2 to 5 weight percent of the matting effect compound;

0 wt% to 8 wt% of a curing agent;

0% to 25% by weight of an agent which increases the solubility of the dye;

0.5 to 19 weight percent of polymer A; And

Other components from 0.2% to 5% by weight,

The weight percent is calculated based on the total weight of the powder coating composition and the total sum of all components of the powder coating composition is 100 weight percent.

The powder coating according to the invention can be applied over a wide range of thicknesses of the film to be applied, typically for example to be applied to thin films of 30 microns or less, or thin films of 50 microns, 100 microns, 150 microns or 200 microns or less. Can be. Typical minimum film thickness is 5 microns.

The powder coating according to the invention can be applied by an electrostatic spray device. Usually, the powder is sprayed under 60 KV to 80 KV at a film thickness of 40 microns to 60 microns. Unused powder can be collected and reused through the application system.

Powder coating compositions according to the invention can be applied to various substrates such as metal, wood, and plastics. When the powder coating composition was applied to an aluminum substrate, the best results were found on substrates with anodized appearance.

ADE-index

The ADE-index is actually an objective way of quantitatively describing anodized surfaces or surfaces with anodized appearance. The ADE-index can be measured using a device that allows color measurements at discrete angles in the plane.

For this measurement, for example, an X-rite MA68II mobile multi-angle spectrophotometer can be used.

The ADE-index can be measured by measuring the reflectance in a direction perpendicular to the longitudinal direction of the observed texture. For each measurement, the L, a, and b values are recorded and the color difference is calculated by the standard color difference equation in a direction perpendicular to the length direction of the texture. Reflectance is measured at the flop angle (110 ° from specular reflection) relative to the surface being measured. The ADE-index is (length of texture minus right angles) ΔE. In fact, for the surface of an anodized object or an object with an anodized appearance, the ADE-index is found to be greater than three. For non-anodized surfaces or surfaces that do not have an anodized appearance, at low or high gloss, the ADE-index is found to be less than two.

In another embodiment, the present invention is directed to a substrate coated with a powder coating having an anodized appearance, meaning that the ADE-index of the coated surface is greater than three.

The powder coating according to the invention exhibits a number of advantageous properties when subjected to various mechanical or chemical tests known to those skilled in the art. The properties are listed in the table below:

Test type Examination process Test result Norman wear
(Norman abrasion) ASTM F2357-04 No visible wear through the substrate or other paint layers after 150 cycles Taber wear
(Taber abrasion) ASTM D4060-07 Coating weight loss is <100 mg Wear ASTM D3359-09 5B in 1mm Square Pencil hardness
(Pencil Hardness) ASTM D3363-05 F to H, no scratch observed under 5x magnification Direct impact
(Direct Impact) ASTM D2794-93 No visible damage to membranes below 20 kg.cm at 16 mm ball diameter Mandel bend
(Mandrel Bend) ASTM D522-93a No visible damage to 1/4 inch Mandrell film Chemical sensitivity ASTM D1308-02 No visible contamination due to universal cosmetics and / or cleansers Water resistance at 100% RH ASTM D2247-02 No visible change after 500 hours Practical water wash
(Practical Washability) ASTM D4828-94 No visible change after 100 cycles (with distilled water, 2.5% ethanol, or 1.84% sodium hypochlorite) Content-based ASTM D4752-03 No visible changes after 20 double rubs with methyl ethyl ketone

T _g of material can be measured using differential scanning calorimetry (DSC). In this measurement, the energy released when the sample is heated is measured. Using the result of this measurement, T _g can be measured. This procedure is well known to those skilled in the art. T _g values mentioned in this document were measured using a heating rate of 20 K / min. Before each measurement, the sample is estimated (T _g ) Short-term heating to just above temperature.

Particle sizes of materials (eg, polymers of powder coating compositions) can be measured using laser scattering techniques, for example using Malvern Mastersizer 3000. Using this device, the particle size distribution as well as the average particle size can be measured. For particle size measurements used in the present application, it is assumed that all particles of the material have a spherical size.

The invention will be explained with reference to the following examples. They are intended to illustrate the invention, but should not be construed as in any way limiting its scope.

Example

Examples 1-8

The polyester-primid powder coating composition was prepared by making a premix of the components of Table 1 below. This premix was then melt processed in a twin screw. After melt processing, the material was cooled and ground to the particle size (typically in the range of 1 μm to 100 μm) used in the powder coating composition.

The powder coating composition was then sprayed onto an aluminum substrate and cured at 200 ° C. for 15 minutes. Both coated substrates showed an anodized appearance (all had more than 3 ACE-index and soft fill).

(Amount expressed in parts by weight) Example  One Example  2 Example  3 Example  4 Example  5 Example  6 Example  7 Example  8 Polyester resin 1 ¹ 416 404 404 404 404 404 403 404 Polyester resin 2 ² 416 426 426 426 426 426 425 426 Hardener 1 ³ 75 76 76 76 76 76 76 76 Quenching effect compound ⁴ 11 11 11 11 11 11 11 11 Soft Peel Polymer ⁵ 54 54 54 54 54 54 54 54 Solvent Soluble Dyes 1 ⁶ One One Solvent Soluble Dyes 2 ⁷ One Solvent Soluble Dyes 3 ⁸ 2 0.5 0.1 Solvent Soluble Dyes 4 ⁹ 0.1 Solvent Soluble Dye 5 ¹⁰ 2 Solvent Soluble Dyes 6 ¹¹ 2 Solvent Soluble Dye 7 ¹² 3 Solvent Soluble Dyes 8 ¹³ 0.04 One Solvent Soluble Dye 9 ¹⁴ 2 0.04 Solvent Soluble Dyes 10 ¹⁵ 3 Solvent Soluble Dyes 11 ¹⁶ One Flow aids 11 11 11 11 11 11 11 11 Benzoin 2 2 2 2 2 2 2 2 ¹ Polyester resin with acid value 90 mg KOH / g, ex Cytec
² polyester resin with an acid value of 25 mg KOH / g
³ Primid XL 552, ex EMS
⁴ Ceridust Wax, ex Clariant
Elvaloy copolymer with ⁵ Tg of -32 ° C, melting point of 45 ° C, average particle size ranging from 1 μm to 60 μm, used for PVC modification, ex DuPont
⁶ Neozapon Red 471 ex BASF
⁷ Microlith Bk CT ex Ciba
⁸ Polysythren Yellow NG ex Clariant
⁹ Polysythren Yellow GG ex Clariant
¹⁰ Solvaperm Red BB ex Clariant
¹¹ Savinyl Green 2GLS ex Clariant
¹² Savinyl Pink 6BLS ex Clariant
¹³ Solvaperm Red G ex Clariant
¹⁴ Polysythren Red GG ex Clariant
¹⁵ Polysythren Blue RLS ex Clariant
¹⁶ Microlith Blue 4G-T ex Ciba

Examples 9-16

The polyurethane powder coating composition was prepared by making a premix of the components of Table 2 below. This premix was then melt processed biaxially. After melt processing, the material was cooled and ground to the particle size (typically in the range of 1 μm to 100 μm) used in the powder coating composition.

The powder coating composition was then sprayed onto an aluminum substrate and cured at 200 ° C. for 15 minutes. Both coated substrates showed an anodized appearance (all had more than 3 ACE-index and soft fill).

(Amount expressed in parts by weight) practice Example 9 practice Example 10 practice Example 11 practice Example 12 practice Example 13 practice Example 14 practice Example 15 practice Example 16 Polyester Resin 3 ¹⁷ 381 381 381 381 381 381 380 381 Polyester Resin 4 ¹⁸ 358 357 357 357 357 357 357 357 Curing Agent 2 ¹⁹ 164 164 164 164 164 164 164 164 Quenching Effect Compounds ²⁰ 11 11 11 11 11 11 11 11 Soft Peel Polymer ²¹ 56 56 56 56 56 56 56 56 Flow aids 13 13 13 13 13 13 13 13 Thixotropic modifier ²² 11 11 11 11 11 11 11 11 Benzoin 3 3 3 3 3 3 3 3 Thickener 11 11 11 11 11 11 11 11 Solvent Soluble Dyes 1 One 2 Solvent Soluble Dyes 2 One Solvent Soluble Dyes 3 3 One 0.1 Solvent Soluble Dyes 4 0.1 Solvent Soluble Dyes 5 2 Solvent Soluble Dyes 6 3 Solvent Soluble Dyes 7 3 Solvent Soluble Dyes 9 2 Solvent Soluble Dyes 8 One Solvent Soluble Dyes 10 3 Solvent Soluble Dyes 12 ²³ 3 Solvent Soluble Dyes 11 One ¹⁷ Polyester resin with acid value 50 mg KOH / g, ex ChangXie
¹⁸ polyester resin with an acid value of 300 mg KOH / g, ex ChangXie
¹⁹ Polyisocyanate Curing Agent B1530, ex Degussa
²⁰ Ceridust Wax, ex Clariant
Elvaloy copolymer with ²¹ Tg of -32 ° C, melting point of 45 ° C, average particle size ranging from 1 μm to 60 μm, used for PVC modification, ex DuPont
²² Modified Derivatives of Castor Oil, ex Elementis
²³ Savinyl Blue RS ex Clariant

Claims (14)

a. Binder resin,
b. Solvent soluble dyes,
c. Matting effect compounds,
d. Polymer A consisting of particles having an average particle size of 0.1 μm to 60 μm and a Tg of −60 ° C. to 75 ° C., and
e. A powder coating composition obtainable by processing a mixture comprising a pigment or dye that is insoluble in a solvent, based on the total weight of the powder coating composition. The method according to claim 1,
The powder coating composition, wherein the solvent soluble dye is a metal complex dye. 3. The method according to claim 1 or 2,
Powder coating composition, characterized in that it comprises an agent for increasing the solubility of the dye in the binder resin. The method of claim 3,
Powder coating composition, characterized in that the agent for increasing the solubility of the dye in the binder resin comprises isocyanate groups. The method according to claim 3 or 4,
A powder coating composition, characterized in that the agent for increasing the solubility of the dye in the binder resin comprises a caprolactam blocking group. The method according to claim 1,
Powder coating composition, characterized in that the composition is substantially free of any opaque pigment. The method according to claim 1,
Powder coating composition, characterized in that the polymer A is a copolymer of carbon monoxide, ethylene and an unsaturated ester monomer. The method of claim 7, wherein
A powder coating composition, characterized in that the (co) polymer consists of 40 mol% to 80 mol% of ethylene, 10 mol% to 60 mol% of vinyl acetate, and 3 mol% to 30 mol% of carbon monoxide. The method according to claim 1,
Powder coating composition, characterized in that the polymer A is a core-shell or layered (co) polymer. Substantially free of any opaque pigment,
40% to 95% by weight of binder resin or mixture of binder resins;
0.2 wt% to 2 wt% of a solvent soluble dye;
0.2% to 60% by weight of the matting effect compound;
0 wt% to 8 wt% of a curing agent;
0% to 25% by weight of an agent which increases the solubility of the dye; And
A powder coating composition obtainable by processing a mixture comprising from 0.2% to 5% by weight of other components,
The weight percent may be calculated based on the total weight of the powder coating composition, wherein the total sum of all components of the powder coating composition is 100 weight percent. A method of making a substrate having an anodized appearance, comprising applying a powder coating composition according to claim 1 to a substrate, heating the substrate, and curing the powder coating. A substrate having an anodized appearance when coated with the powder coating composition according to claim 1. 13. The method of claim 12,
A substrate, characterized in that the substrate is an aluminum substrate. A substrate coated with a soft feel powder coating having a coated surface with an ADE-index> 3.