DE4008361A1 - POWDER-COATING COATING COMPOSITION - Google Patents

Abstract

A powder coating composition comprises a dry particulate mixture of (1) a thermosetting or thermoplastic resin and (2) vesiculated polymer granules having a volume mean diameter of 3 to 30 microns and formed of a polymeric material which is not melted or degraded during any of the conditions of time and temperature which arise during preparation or use of the compositions. The amount of the polymer granules in the composition is at least 40% by volume. The powder coating compositions produce a matt finish rather than the previous glossy style. The polymeric granules preferably are spherical and the vesicles occupy from 5 to 95% of the volume of the granules. The power compositions can be used to wide variety of uses.

Description

The present invention relates to resinous compositions tions, in particular pulverulent coating Compositions. Powder Coating Composition Compositions are increasing in quantity and in one growing number of application areas used. you have great merits, but because of their application process, the coatings produced tend to a more shiny instead of a matt surface Show texture. However, there is a need for creating a matt surface texture.

According to the present invention contains a powdery Coating composition essentially dry, particulate mixture of one cure resin or a thermoplastic resin and vesicles containing polymer grains having a mean Volu diameter of 3 to 30 microns, which consists of a polymeric Material manufactured under all, to Her position of the composition and also to cure the thermosetting resin composition required Tempe temperature and time conditions and for all to apply a thermoplastic resin composition on a Substrate required temperature and time conditions not melted or degraded appreciably. The Proportion of polymer grains should be less than 40 vol .-% of Mixture amount.

The inventive powdery coating Zu Compositions are based on a resin that either a thermosetting or a thermoplastic resin, wherein Compositions based on thermosetting resins, are preferred. Among curable resins are those too  understand when curing, usually under Ver use of a curing agent, do not melt or do not soften when heated.

In general, typical thermosetting resins are epoxy resins, polyurethanes, polyester resins, epoxy-polyester Mixed resins and acrylic resins. There are epoxy resins obtained Lich, by the action of a curing with under different speed, also from the Curing temperature depends, cure. There are Compositions available within 60 seconds or less, melt and harden.

Curing agent is generally used on the Basis of dicyandiamide, especially the modifi ornamented and substituted derivatives.

Polyester resins such. As saturated, oil-free resins the basis of isophthalic or terephthalic acids, are reacted with diols to form hydroxyl-terminated ones Resins to be prepared, which are used in the invention can. Such resins can be made by reaction with a Amino resin, e.g. As a melamine-formaldehyde resin be hardened. Polyester resins with free hydroxyl groups can with isocyanates, such as. B. one, with a Blocking agent, e.g. B. caprolactam-blocked iso phoron diisocyanate are cured. Such outgoing Teten resins contain urethane groups and are therefore in the tight sense polyurethanes. You can also use other polyesters use, which contain carboxyl groups, these using polyepoxides, e.g. B. triglycidyl Isocyanurate can be cured.

It is still possible to mix as thermosetting resins to use polyester, which is the reaction product of a Epoxy resin and a polyester can be.  

You can also use curable acrylic resins, z. B. by polymerizing a methacrylate on an acrylic backbone are available. For cross-linking or Här tion of the resin can be used dibasic acids. Other suitable curing agents are carboxy-terminated Polymers.

Thermoplastic resins used in the manufacture of the inventions The powdery coating composition according to the invention are suitable polyvinyl polymers, polyamides, thermoplastic polyesters, polyolefins and celluloses. Usually, the resins are plasticized polyvi nylchloride, polyamides with suitable melting temperature, Polyethylene, polypropylene, resins from cellulose acetate Bu tyrate, polyester based on terephthalic acid and 1,4-butanediol, ethylene chlorotrifluoroethylene polymers, Polyvinylidene fluoride and polyphenylene sulfide.

In general, the powders according to the invention contain shaped coating compositions, in case it is a curable resin composition, also a curing agent for the resin (as previously be written), a flux and the vesicles containing Polymer grains. In the case of a powdered Be coating composition on the basis of a thermoplastic resin contains the composition in general a plasticizer, a stabilizer and the vesicle-containing polymer grains.

The resin composition may, if necessary or desired, pigments such as titanium dioxide and colored pig contain pigments and dyes. Titanium dioxide color and / or colored pigments may be present in the composition inside or outside of the vesicle-containing poly present.  

The grains of a polymer material contain an or several vesicles whose walls are formed by the polymer become. Preferably, the grains are essentially of spherical shape and the vesicles take 5% to 95% of the Total volume of grains. Particularly preferred the vesicles contain 20% to 80% of the volume of the grains on.

The grains are of such size that the middle one Volume diameter of 3 to 30 microns, preferably from 5 is up to 20 microns.

In general, the vesicles are in the preferred Kör essentially spherical in shape and have a diameter of less than 20 microns, preferably from 0.1 to 7 microns, more preferably from 0.1 to 1 micron.

In general, the polymer type of the grains is not we sentlich. It can be a polyester that goes through Condensation of a polycarboxylic acid and a polyol is available, a polyester amide, a polyurethane, a Urea-aldehyde resin, a cellulose ester or any another suitable material. Preferably the polymer is an unsaturated polyester resin with an unsaturated monomer is crosslinked.

Although the grains of a wide range of different Polymers, the polymer, in the case of a curable resin composition, below the temperature and time conditions when mixing or Making the composition as well as later Curing and, in the case of a thermoplastic Zusam composition, under the conditions of temperature and time applying the composition to a substrate do not melt or degrade appreciably.  

Other types of polymer particles suitable for use with the present invention are suitable as what serunlösliche core / shell polymer particles known in the special ones with a single vesicle per Particles. In such particles, the core is one formed polymeric material that in contact with a suitable substance swells, and the shell is made of a made of other polymeric material suitable for the Substance is permeable, which reacts with the nucleus is needed.

The polymeric grains can, if desired, a pig ment such as B. contain a titanium dioxide pigment, which in the vesicles or in the polymeric material or in both can be present. The grains can after each suitable methods, but usually this involves the production of a water-in-oil Emulsion of a polymeric material, e.g. B. a poly ester resin dissolved in an oil material, e.g. Styrene or a crosslinking monomer. This emulsion is then dispersed in a further aqueous phase. The poly merization produces an aqueous dispersion of polymer grains with vesicles.

The aqueous dispersion of polymer granules, which after the can be prepared according to the preferred method patent specification GB 22 05 154A to be dried. Then the ge Dried composition used to be the powdered coating composition herzustel len. According to the patent GB 22 05 154A of Fenced and described method is the aqueous Dispersion by heating under an oxygen-free Dried atmosphere, with such time and tempera  tur conditions that a significant degradation the particles remain as low as possible.

If the polymer grains contain a pigment, the Proportion of the pigment from 1 to 60% by weight of the weight of Grains amount, preferably from 5 to 45 wt .-%.

The proportion of polymer grains in the powdery Be coating composition can be over a wide Range, but should be less than 40% vol. the composition and preferably 5 to 30% by volume be.

In general, there are two main methods for the her Position of powdered coating composition tongues, namely a melt-mixing method and a Dry-mixing process.

In a melt-blending process, the resin, the Vesicle-containing polymer grains and the other Kom components are mixed together in dry form and then heated, wherein before cooling, a mixture or an extrusion takes place. The heating should be sufficient be to the resin contained in the mixture, but not the Grains to melt. Likewise should temperature and Treatment time is insufficient to make an unacceptable premature curing of a curable resin composite effect. The extruded or on others Way mixed composition is cooled, granu and to a desired final particle size ground. If desired, can be packed before packing still required additives in the composition be introduced.  

In a dry-blending process, the resin becomes fine partial form with the vesicle-containing Polymerkör ners and other desired components together in mixed in a high performance mixer. The mixed Composition is cooled and, if desired, Additives can be added later. so far away desired, the mixed composition sieved to unwanted part before packing with too big or too small a size.

The powdery coating compositions according to of the present invention can be used for a wide range of applications be used by each of the widely used techniques such. B. electrostatic Spray coating, fluid bed coating, elektrosta table fluid bed coating and hot flocculation be brought. The application is preferably carried out by electrostatic spray coating.

It should be clarified that the invention powdery coating compositions in the white are substantially dry, particulate mixtures and essentially free of solvents or dispersants tion media.

Coated products are manufactured which have a matt surface texture with an even have a spotless appearance. Before using Vesicle-containing polymer grains had products matt surface texture not the required Liche appearance, sometimes even they had an un evenly spotty surface texture.

The products of the invention are suitable for Be layering of a wide range of products in the Home or outdoors can be used.

The invention is ver by the following examples clear, all parts being parts by weight.

Example 1 (Production of beads)

An unsaturated polyester resin was made by Cokondensa tion of maleic anhydride, phthalic anhydride and Propylene glycol in the molar ratio 3: 1: 4.5 produced. The The product had an acid value of 16 mg KOH per gram solid resin.

44 parts of a solution of the above resin in styrene with a 57 wt .-% solids content was 3.5 tei len titanium dioxide pigment, which under the name TIOXIDE R-HD6 is available, and 0.18 parts Magne mixed until a thorough dispersion had occurred (about 30 minutes). To this mixture were 20 parts of styrene and 4.9 parts of hot water (about 80 ° C) was added and mixed with one Continued for a minute. This oil phase then became one Let stand for an hour.

Separately, 0.6 part of an aqueous solution an ammonium nonylphenol ethoxylate sulfate surface active agent with a 90 wt .-% solids content with 0.18 parts industrial, denatured with methanol Alcohol and 0.42 parts of water mixed. This Ge mixed with 42 parts of water at 50 ° C, so that an aqueous phase was obtained which slowly submerged Stirring was added to the oil phase. The resulting Ge mix was mixed for 10 minutes to obtain a water-in To produce oil emulsion.  

45.5 parts of this emulsion were immediately converted to a white aqueous phase added, the 5 parts of a poly vinyl alcohol solution with 7.5% by weight solids (as Stabilizer), 1 part of a hydroxyethyl cellulose Ver Thickener solution with a solids content of 1.5% by weight and 80 parts water. The resulting mixture was mixed for 3 minutes. Then there was a what ser-in-oil-in-water system with oil globules of one formed average diameter of about 11 microns.

Subsequently, 28 parts of hot water under ge as possible, followed by 0.006 Share ferrous sulfate, dissolved in a small amount Water, 0.1 parts of diethylenetriamine, as well in one dissolved small amount of water, and 0.156 parts of cumene hydroperoxide. The slurry was passed over undisturbed Let stand overnight and warm to above 50 ° C complete crosslinking of the unsaturated polyester sure. This gave a slurry of cross-linked, vesicle-containing, pigmented Polyester resin beads having a solids content of 16.1% by weight.

This slurry was described as follows according to the British Patent Application GB 22 05 154A disclosed and claimed method dried. To 4000 parts of the slurry were 15 parts of a 10% ammonia solution and 40 parts of a 5% solution given a Flokkulationsmittels. At the flokkula tion agent is the monoacetate salt of a Diamins derived from a fatty acid. to Finally, the slurry was heated to 70 ° C and stirred until the onset of flocculation. The approach was filtered through a conventional vacuum filter and then washed with clear water until no Polyvinyl alcohol be detected more in the filtrate  could. The test for polyvinyl alcohol was carried out conducts by taking a sample of the filtrate with 10 × its Volume of acetone mixed, whereupon the included polyvi nylalkohol is precipitated as white turbidity. The resulting filter cake contained 18.4 wt .-% of ku gel-like solids.

2 kg of the filter cake were broken up and placed on a Bowl placed in an oven with a thermostat equipped and flushed with nitrogen gas could. Then the cake became 16 hours long heated to 110 ° C under a nitrogen atmosphere, after which no further weight loss festge could be.

The dry globules formed a soft, crumbly one white mass, without residue through a sieve with Öff milling of 106 microns could be ground.

example 2 (Default)

A common powdery coating with a PVC (Pigment volume concentration) of 15% was after the following method. 692 parts of one before crushed epoxy resin (Dow 663 U), 102 parts of a comminuted flow control base mixture (5% by weight) Modaflow eluent (an ethyl acrylate and 2-ethylhexyl acrylate copolymer) in Dow 663 U epoxy resin), 40 parts Hardener, which is an accelerated cyanogen diamid (Dow DEH 41) and 500 parts titanium dioxide Pigment, available under the name TIOXIDE TR 92, were mixed in a water-cooled Henschel mixer. The Blending was done for 5 minutes at a rotor speed performed at 1800 rpm. The pages and the  Rotor of the machine were after an initial Scraped for 3 minutes.

The resulting premix was made using of a PR 46 Buss co-kneader moving at slow speed was operated, extruded at 100 ° C, then cooled and in a small granulator (Cumberland) crushed. The crushed extrudier Product was then closed in a mini KEK pin mill ground and the powder produced through a 200 mesh sieve sieved before spraying all particles with more than to remove 75 microns.

The powder was made using a manual Volstatic electrostatic spray device on bonding rite DG 12 (iron phosphate) sheets applied, the Voltage was set to -90 kV. The powder was by drying the sheets for 10 minutes at 180 ° C in the oven melted and become a continuous coating hardened. To measure the coating thickness was a Permascop, type ES used, there were sheets with a coating thickness after curing between 45 and 55 μm selected.

Color measurements on the panels were made using a Gardner XL-23 colorimeter. The values for L and b were determined on the CIE Lab scale. The gloss was measured using a Byk-Labotron Multi gloss Glossmeter.

Example 3 to 6 (Invention)

It was a series of powder coatings herge What are the dry, vesicular pigmented polymer beads contained according to  Example 1 were produced. The pigment volume Concentration was left at 15% while the Ball volume concentration (BVC) between 10% and 40% was varied. The powder coatings were after the same method as in Example 2, wherein the beads at the same time as the pigment were added. The quantities used, in weight divide were as follows:

The tests were carried out as in Example 2. The Results are shown below in tabular form provides.

example 7 (Comparison)

Another powder coating was produced wherein an inorganic filler (calcium carbonate, Durcal 5) of substantially the same size as the Beads were used in their place. The pigment Volume concentration was left at 15%, and one Filler volume concentration (EVC) of 20% was used. The powder coating became the same Process as prepared in Example 2. The used Quantities, in parts by weight, were as follows:

Example 7 PVC | 15% EVC 20% epoxy resin 531 Flow control masterbatch 78 Harder 30 TiO₂ pigment 500 filler 443

The test was as described in Example 2, Runaway leads. The results were as follows:

Results of Examples 2 to 7

Example 6 with 40% BVC had previously not been melted in a covering coating, and was therefore not a viable system. Example 7, with 20% EVC, showed a significantly lower brightness than the standard (Example 2) or the powder coating with an equal volume of beads (Example 4). Its gloss was significantly higher than that in Example 4, thus the beads are apparently the superior mat tierungsmittel. The increase in value of b (ie yellowish) with increasing BVC was not due to thermal decomposition of the beads, as a sample of the beads heated under the same conditions showed only a very small color change.

However, the one in each of these examples is verwen hardener (Dow DEH 41) an amine. Amines are in general Believe me that you are using polyesters Heating interact so that yellowish or brownish Products are created.

Example 8 (Default)

A common powder coating with a PVC of 15% was prepared according to the following procedure: 691 parts a previously comminuted polyester resin (Uralac P 2400, from DSM Resins), 58 parts triglycol isocyanurate (TGIC, Araldite PT 810, from Ciba-Geigy), 93 parts crushed Flow modifier (Urad P 2518, from DSM Resins) and 500 Parts of a general-purpose titanium dioxide pigment, available under the name TIOXIDE TR 92, were in a wasserge cooled Henschel mixer mixed. The blending became 5 Minutes at a rotor speed of 1800 rpm carried out. The walls and the rotor of the machine wur after an initial 3-minute mixing period scraped.

The resulting premix was in an extruder (PR 46 Buss Ko-Kneader), which at 100 ° C with slower Speed was operated, extruded, then abge cool and in a small Cumberland granulator crushed. Subsequently, the crushed extru milled in a pin mill (mini-KEK) and the produced powder was sieved through a 200 mesh sieve to all particles more than 75 microns before spraying too remove.

The powder was made using a manual elec trostatic spray device (Volstatic) on iron Phosphate sheets (Bonderite DG 12) applied, the  Voltage had been set to -90 kV. The powder was melted and made into a continuous Beschich Hardened by the sheets for 10 minutes at 200 ° C were heated in an oven. To measure the Coating thickness was a Permascop, type ES, ver applies. There were sheets with a coating thickness after curing selected between 45 and 55 microns.

Color measurements on the panels were made using a Gardner XL-23 colorimeter. The values for L and b were measured on the CIE Lab scale. Gloss was measured using a Byk-Labotron Miltigloss Glossmeter.

Example 9 to 10 (Invention)

Two powder coatings were produced, which the dry, vesicles containing, pigmented Polymer beads according to Example 1 contained. The pig ment volume concentration was maintained at 15% and the spherical volume concentration (BVC) was reduced to 10% and 20% set. The powder coatings were after prepared according to the method of Example 8, wherein the Beads added in the same stage as the pigment ben were. The quantities used were in weight divide as follows:

The test was carried out as in Example 8. The Re results are shown below in tabular form.

example 11 (Comparison)

Another powder coating was produced wherein, instead of the beads, an inorganic filler (Calcium carbonate, Darcal 5) of substantially the same Size as the beads was used. The pig ment volume concentration was left at 15%, while a filler volume concentration (EVC) of 20% was used. The powder coating was after prepared according to the method of Example 8. The verwen The quantities, in parts by weight, were as follows:

Example 11 PVC | 15% EVC 20% polyester resin 533 TGIC 45 Fließmodifikator 72 TiO₂ pigment 500 filler 450

The test was carried out as in Example 8. The Re results are shown below in tabular form.

Examples 12 to 13 (Invention, dry mixing)

There were other powder coatings with intermediate Grain volume concentrations prepared by the same Volume of 2 powdered coating powders with  different BVC were mixed, so that a Pro was obtained with an effective BVC, which is the Average of the individual BVC's corresponded. As a sample was a mix of the 20% BVC system and the 0% BVC system (standard), whereby an effective BVC of 10% was obtained. This mixture possessed the identical properties as a powder coating, which was manufactured ab inito with a 10% BVC. Therefore, the blends of powders with 0% BVC and 10% BVC (resulting in an effective BVC of 5%) and of powders with 10% BVC and 20% BVC (resulting in an effective BVC of 15%) as equivalent to Pul considered ab inito with 5% BVC or 15% BVC were produced. The powders were like applied and tested in Example 8. The results are shown in the following table.

Results of Examples 8 to 13

Example 11 with a 20% EVC had a much lower brightness than the standard (Example 8) or the powder coating with an equal volume of grains (Example 10). Its gloss was much higher than that in Example 10, so the grains are a superior matting agent. The increase in the value of b (ie, the yellowish tinge) with increasing BVC was much lower than in the corresponding epoxy system (Examples 2 to 6) and would not be a significant disadvantage in use. It is noteworthy that in graphic representation of the 60 ° gloss against the BVC in Examples 8, 9, 10, 12 and 13, there was a linear relationship between the two variables. The majority of matting agents have a much lower direct effect on gloss. Therefore, these grains make it much easier to select a BVC to obtain a required 60 ° gloss result.

Claims (13)

Claims 1. A powdery coating composition comprising a substantially dry, particulate mixture of a curable resin or a thermoplastic resin, characterized in that the mixture contains vesicular polymer granules having a median volume diameter of from 3 to 30 microns and consisting of one Polymerma terial are formed, which neither melts, nor decomposes appreciably under all temperature and time conditions, which are required for the preparation of the composition and also for curing the curable resin composition and under all temperature and time conditions for the application of the thermoplastic Resin composition are required on a substrate, wherein the proportion of the polymer grains is less than 40 vol .-% of the mixture. 2. Composition according to claim 1, characterized characterized in that the grains are spherical and a medium volu diameter of 5 to 20 microns own. 3. Composition according to claim 1 or 2, characterized, that the grains have vesicles, one in the we have significant spherical shape and a Have diameters of less than 20 microns. 4. Composition according to claim 3, characterized characterized in that the vesicles have a diameter of 0.1 to 1 micron.   5. Composition according to one of the preceding An sayings, by characterized in that the grains Vesicles containing 5% to 95% of the total vo take lumens of the grains. 6. Composition according to one of the preceding An sayings, by characterized in that the proportion of the grains 5% to 30% of the volume of the mixture is. 7. Composition according to one of the preceding An sayings, by characterized in that in the Mi Titanium dioxide pigment is also present. 8. Composition according to claim 7, characterized characterized in that the titanium dioxide is present in the grains. 9. Composition according to claim 8, characterized characterized in that the proportion of titanium dioxide in the grains from 1 to 60% by weight the grains amounts. 10. Composition according to one of the preceding An sayings, by characterized in that the poly merkörner core / shell polymer particles are. 11. The composition according to claim 10, characterized characterized in that each grain has a single vesicle.   12. A method for producing a powdery A coating composition comprising the Ver Mix a curable resin or a thermo plastic resin with the other ingredients, characterized, that the resin with vesicles containing Polymerkör mixed with a medium volu diameter of 3 to 30 microns and from a polymer material are formed which neither melts, yet decomposes appreciably among the respective temperature and time conditions of Mixing and those used to harden the curable Resin composition are required, and the Temperature and time conditions for application the thermoplastic resin composition on a Substrate are required, the proportion of Polymer granules less than 40 vol .-% of the mixture is. 13. The method according to claim 12, characterized characterized in that the mixture is heated to melt the resin and the Ge Mix before chopping to the desired end size is extruded and cooled.