High solids low viscosity pigment paste, method of making and use in low voc coil polyester finishes

Abstract

The application discloses a high-solid and low-viscosity color paste, a preparation method thereof and application of the color paste in low-VOC coiled polyester finish, which comprises 10-70 parts of pigments, 20-60 parts of grinding resins, 1-50 parts of dispersants and 5-40 parts of first solvents. The color paste is suitable for color matching of coiled polyester finish and can be used to prepare a series of coiled polyester finish products with different colors, low VOC (less than 420 g / L) and high coating rate characteristics.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of coil coating. More particularly, it relates to a high-solid low-viscosity color paste, a preparation method thereof and application of the color paste in low-VOC coil polyester topcoat. BACKGROUND

[0002] The earliest coil coating in the world appeared in the 1930s, and China began to gradually establish coil coating production lines after the 1980s. Pre-coated coil coating is a special coating with certain physical properties and resistance, which can be coated on continuous metal sheets using fast and automated production lines, and the film is formed after high-temperature curing. The pre-coated coil product after coating is widely used in various fields such as construction, household appliances, containers, automobile manufacturing, cookware, etc. Pre-coated coil products have the advantages of energy saving, environmental protection, high efficiency, good coating quality, etc. Therefore, since Wuhan Iron and Steel Company formally introduced the first pre-coated metal coil production line in China in the 1980s, the number of production lines has rapidly developed to more than 500 by 2015; the amount of coil coating used has also grown rapidly, and according to incomplete statistics, the amount of domestic coil coating used in 2018 was about 350,000 tons. It is estimated that by 2025, the amount of domestic coil coating will reach 500,000 tons.

[0003] At present, in the production process of traditional pre-coated metal coil, most of the coil coating products are solvent-based systems, and the volatile organic compounds (VOC) content of the organic solvent waste gas generated during the baking process cannot meet the requirement of ≤420 g / L, and even during the process of making, transporting and using coil coating, such as storage, stirring, production preparation, coating construction, etc., there is still a large amount of organic solvent volatilization, which affects people's health and pollutes the construction environment. It is very difficult and costly to adjust the coil production line, so developing high-solid coil coating to meet environmental protection requirements is a more feasible route.

[0004] On the other hand, the national standard "Technical Requirements for Low-VOC Coating Products" (GB / T 38597-2020) has been officially released and will be implemented from February 1, 2021; the new standard also defines the content of organic compounds in coatings more clearly. Under such background, it is also an urgent problem to be solved in the industry to develop and launch low-VOC coil polyester topcoat that meets the latest regulations.

[0005] For coil polyester topcoat, its film thickness is usually only 10-20 μm, in order to meet the requirements of hiding power, the formula often needs to include a higher pigment concentration; and in order to achieve the desired color effect, the pigment needs to be uniformly distributed in the form of fine particles in the coating film, which requires sufficient dispersion of the pigment, this process usually has two ways to achieve: the first way is to use the main resin of the topcoat to grind and disperse one or more pigments into a mill base, and then add paint (such as resin), solvent and additives to make finished paint; the second way is to prepare a separate pigment concentrate, that is, a color paste, and then add different colors of color paste to the resin base according to the color requirements to make finished paint.

[0006] In order to adapt to the characteristics of the coil production line process, it is usually necessary to adjust the viscosity of the coil topcoat with a diluent to obtain better material lifting and roll coating performance, and the amount of diluent often directly determines the VOC of the finished paint. If the dispersion effect of the resin on the pigment is poor, the viscosity of the dispersion system obtained is high, so more diluent is needed to adjust the viscosity of the finished paint, resulting in an increase in the VOC of the paint. On the other hand, if a separate dispersion of pigments is used to prepare a color paste for color matching, the viscosity characteristics of the system after the color paste is added to the base directly determine the amount of diluent and the VOC content of the finished paint.

[0007] US patent No. US8969438B2 discloses a pigment concentrate containing at least one oligoester structural unit having a hydrophobic tail chain attached thereto, such as using an alicyclic hexahydrophthalic anhydride to esterify a monoepoxide (such as a glycidyl ester) with a hydrophobic tail chain to obtain an oligoester structural unit, and then further polycondensing with a polyol to obtain the final polyester. Although this patent discloses a method for preparing a high-solid and low-VOC solvent-based color paste, it emphasizes the VOC content of the color paste itself, but does not disclose the application of the prepared color paste in coil polyester topcoat, especially the performance of VOC.

[0008] For coil coatings, a variety of different colors of pigments are often used in the formula to match the required accurate color. In order to disperse the pigments uniformly in the paint, the process usually used in the production process mainly has three ways:

[0009] The first is color mixing grinding, that is, a method of mixing and grinding a plurality of pigments, which is to mix all the pigments used in the color paint formula together, and grind and disperse them into a mill base using a sand mill or other grinding and dispersing equipment, and then add paint (resin), solvent and additives to make finished paint.

[0010] The second is single-color grinding, i.e. single pigment grinding, after grinding, the semi-finished paint is obtained by adding paint (resin), solvent and additive, and then different colors of semi-finished paint are used to adjust color to prepare finished paint.

[0011] The third is to prepare pigment concentrate, i.e. color paste, and then different colors of color paste are added to resin base to adjust color to prepare finished paint.

[0012] Therefore, the present application designs a high-solid polyester based on aromatic anhydride, which disperses pigments by synergistic effect with specific dispersants to prepare high-solid low-viscosity color paste, when applied to coil polyester topcoat, the VOC content of the final paint product is less than 420 g / L, and the application performance such as film performance, chemical resistance and long-term durability is not affected. SUMMARY

[0013] In order to overcome the above technical problems in the prior art, the present application provides a high-solid low-viscosity color paste, a preparation method thereof and application thereof in low-VOC coil polyester topcoat.

[0014] The first object of the present application is to provide a high-solid low-viscosity solvent-based color paste, which is suitable for color adjustment of coil polyester topcoat and can be used to prepare a series of coil polyester topcoat products with different colors, low VOC (<420 g / L) and high coating rate characteristics.

[0015] The second object of the present application is to provide a preparation method of high-solid low-viscosity color paste.

[0016] The third object of the present application is to provide application of high-solid low-viscosity color paste in coil topcoat.

[0017] To achieve the above first object, the present application provides a high-solid low-viscosity color paste, which comprises 10-70 parts by weight of pigment, 20-60 parts by weight of grinding resin, 1-50 parts by weight of dispersant and 5-40 parts by weight of first solvent.

[0018] In an embodiment, the high-solid low-viscosity color paste further comprises less than 2 parts by weight of synergistic agent (preferably less than 1 part by weight), and less than 3 parts by weight of anti-settling agent (preferably less than 1 part by weight). It is known to those skilled in the art that whether to add synergistic agent and anti-settling agent and the weight parts of the added can be selected according to the type of pigment.

[0019] In an embodiment, the pigment is organic and / or inorganic pigment. Pigment is a substance that provides color, and any pigmentable substance that can be used in coil paint is within the scope of the foregoing pigment selection.

[0020] In an embodiment, the organic pigment is selected from black pigments and / or color pigments. Specifically, the organic pigment includes, but is not limited to, pigments selected from the following classes: disazo pigments, disazo condensation pigments, dibenzpyrenequinone pigments, anthraquinone pigments, anthrapyrimidine pigments, benzimidazolone pigments, quinacridone pigments, quinophthalone pigments, diketopyrrolopyrrole pigments, dioxazine pigments, indanthrone pigments, isoindoline pigments, isoindolinone pigments, perylene pigments, phthalocyanine pigments, pyrazoloquinazolone pigments, and combinations thereof.

[0021] In an embodiment, the disazo pigments are selected from C.I. Pigment Yellow 12, 13, 14, 16, 17, 81, 83, 106, 113, 126, 127, 155, 170, 174, 176, and / or 188, and C.I. Pigment Orange 16, 34, and 44.

[0022] In an embodiment, the disazo condensation pigments are selected from C.I. Pigment Yellow 93, 95, and 128, or, C.I. Pigment Red 144, 166, 214, 220, 221, 242, and 262, or, C.I. Pigment Brown 23 and 41.

[0023] In an embodiment, the dibenzpyrenequinone pigments are selected from C.I. Pigment Red 168.

[0024] In an embodiment, the anthraquinone pigments are selected from C.I. Pigment Yellow 147 and 199, or, C.I. Pigment Red 177.

[0025] In an embodiment, the anthrapyrimidine pigments are selected from C.I. Pigment Yellow 108.

[0026] In an embodiment, the benzimidazolone pigments are selected from C.I. Pigment Yellow 120, 151, 154, 180, 181, or, C.I. Pigment Orange 36 and 72, or, C.I. Pigment Red 175, 185, 208, or, C.I. Pigment Brown 25, or, C.I. Pigment Violet 32.

[0027] In an embodiment, the quinacridone pigments are selected from C.I. Pigment Orange 48 and 49, or, C.I. Pigment Red 122, 202, 206, and 209, or, C.I. Pigment Violet 19.

[0028] In an embodiment, the quinophthalone pigments are selected from C.I. Pigment Yellow 138.

[0029] In an embodiment, the diketopyrrolopyrrole pigments are selected from C.I. Pigment Orange 71, 73, and 81, or, C.I. Pigment Red 254, 255, 264, 270, and 272.

[0030] In one embodiment, the dioxazine pigment is selected from C.I. Pigment Violet 23.

[0031] In one embodiment, the indanthrone pigment is selected from C.I. Pigment Blue 60 and 64.

[0032] In one embodiment, the isoindoline pigment is selected from C.I. Pigment Yellow 139 and 185, or, C.I. Pigment Orange 61 and 69, or, C.I. Pigment Red 260, or, isoindolinone pigments, or, C.I. Pigment Yellow 109, 110 and 173.

[0033] In one embodiment, the perylene pigment is selected from C.I. Pigment Red 123, 149, 178, 179 and 224, or, C.I. Pigment Violet 29, or, C.I. Pigment Black 31 and 32.

[0034] In one embodiment, the phthalocyanine pigment is selected from C.I. Pigment Blue 15, 15:1, 15:2, 15:3, 15:4, 15:6, 16, or, C.I. Pigment Green 7, 36.

[0035] In one embodiment, the pyrazoloquinolone pigment is selected from C.I. Pigment Orange 67 or C.I. Pigment Red 216.

[0036] In one embodiment, the inorganic pigment is selected from a colouring pigment and / or a nacreous pigment.

[0037] In one embodiment, the colouring pigment is selected from a black pigment, a white pigment or a coloured pigment.

[0038] In one embodiment, the white pigment is titanium dioxide (C.I. Pigment 6).

[0039] In one embodiment, the black pigment is selected from black iron oxide (C.I. Pigment Black 11 ), iron manganese black, spinel black (C.I. Pigment Black 27), carbon black (C.I. Pigment Black 7), graphite (C.I. Pigment Black 10) or chromium oxide iron black (P. Brown 29).

[0040] In one embodiment, the coloured pigment is selected from red iron oxide (C.I. Pigment Red 101 ), brown iron oxide (C.I. Pigment Brown 6 and 7), yellow iron oxide (C.I. Pigment Yellow 42), nickel titanium yellow (C.I. Pigment Yellow 53; C.I. Pigment Yellow 157, 158, 159, 160, 161, 162, 163, 164 and 189), spinel phase (C.I. Pigment Yellow 119) or bismuth vanadate (C.I. Pigment Yellow 184).

[0041] In one embodiment, the body pigment is an inorganic pigment, preferably selected from transparent silica, alumina, aluminum hydroxide, natural and synthetic mica, talc, kaolin, calcium carbonate (such as natural and precipitated chalk), and / or barium sulfate.

[0042] In one embodiment, the grinding resin is a high solid saturated polyester with high hydroxyl value, having one or more of the following characteristics:

[0043] (1) a number average molecular weight of 1500-3000 (preferably 1800-2200);

[0044] (2) a PDI of 1.0-5.0 (preferably 2.0-3.0, more preferably 2.2-2.6);

[0045] (3) a hydroxyl value of 80-150 mgKOH / g (preferably 120-140 mgKOH / g);

[0046] (4) a mass solid content of 75-80%; and / or

[0047] (5) a viscosity of X-Z2.

[0048] In one embodiment, the method for preparing the grinding resin comprises the following steps:

[0049] i. adding 40-80 parts by weight of phthalic anhydride, 5-25 parts by weight of isophthalic acid, 15-35 parts by weight of adipic acid, 10-30 parts by weight of trimethylolpropane, and 40-90 parts by weight of neopentyl glycol into a reaction kettle, heating under inert gas protection, starting stirring when the kettle temperature reaches 120-180°C, then adding 0.02-0.05 parts by weight of organic tin catalyst, controlling the material temperature in the kettle at 220-250°C, and reacting for 5-10 hours;

[0050] ii. cooling the reaction kettle to 120-180°C, adding 30-40 parts by weight of diluent, filtering after the solid content reaches 75-80%, to obtain the grinding resin.

[0051] In one embodiment, the method for preparing the grinding resin further comprises, between step i and step ii, a step of adding 1-10 parts by weight of dimethylbenzene into the reaction kettle until the material acid value is <10 mg / g of KOH as the reaction endpoint.

[0052] In one embodiment, the method for preparing the grinding resin, the diluent is selected from one or more of butyl acetate, S-150 solvent oil, S-100 solvent oil, mixed dibasic acid ester, and dimethylbenzene.

[0053] In one embodiment, in the high-solids, low-viscosity solvent-based color paste, the dispersant is selected from polyester-type polymer dispersants, polyurethane-type polymer dispersants, and / or acrylate-type polymer dispersants. These dispersants are all polymer dispersants, exhibiting good compatibility and synergistic effects with milled polyesters. Furthermore, these dispersants contain functional groups with excellent affinity for pigments and solvated chains that can freely extend in the selected first solvent system. The pigment-affinity groups in these dispersants are generally polar groups, such as carboxylic acid groups, phosphoric acid or phosphate ester groups, amino groups, amide groups, urethane groups, etc.; the solvated chains in the dispersant have similar polarity to the solvent system in the color paste. In this case, the solvated chain segments of the dispersant have optimal extension, thereby maximally preventing mutual flocculation between pigment particles. These solvated chains can be low-polarity alkane chains or polyester chains, medium-polarity polyester chains, or acrylate chains.

[0054] In one embodiment, in the high-solids, low-viscosity solvent-based color paste, the dispersant has a solubility parameter SP of 10.0 to 13.0 (preferably 10.5 to 12.5), a number-average molecular weight of 2000 to 20000 (preferably 2500 to 10000), and a PDI of 1.0 to 5.0 (preferably 1.0 to 3.0).

[0055] In one embodiment, the dispersant is Byk Chemie. The dispersant is preferably BYK-110, BYK-161, BYK-163, BYK-170, BYK-180, BYK-2000 and / or BYK-2013.

[0056] In one embodiment, the dispersant is BASF. The dispersant is preferably Efka PU 4010, Efka PU 4050, Efka PA 4401 and / or PX 4330.

[0057] In one embodiment, the dispersant is from Lubrizol. The dispersant is preferably Solsperse 24000 and / or Solsperse 32500.

[0058] In one embodiment, the dispersant is NUOSPERSE FX 9360 from Elementis.

[0059] In one embodiment, in the high solid low viscosity solvent based color paste, the first solvent is selected from one or a combination of butyl acetate, S-150 solvent oil, S-100 solvent oil, mixed dibasic ester, xylene, propylene glycol methyl ether acetate, dipropyl ketone alcohol.

[0060] In one embodiment, in the high solid low viscosity solvent based color paste, the synergistic agent is a pigment derivative. Preferably, it is a phthalocyanine blue derivative and an azo pigment derivative. Such compounds can enhance the adsorption of dispersant on the surface of pigment, further improving the wet dispersion of grinding resin and dispersant on pigment to produce a color paste with more excellent flowability;

[0061] In one embodiment, the synergistic agent can be selected from Solsperse 5000, a phthalocyanine blue derivative, or Solsperse 22000, an azo pigment derivative, both of which are products of Lubrizol Corporation.

[0062] In one embodiment, the anti-settling agent is selected from one or a combination of fumed silica, hectorite clay, and polyamide wax. Preferably, it is fumed silica.

[0063] According to the present application, the high solid low viscosity solvent based color paste has a solid content higher than 50%, and preferably higher than 75%. For example, the solid content of organic pigment based color paste and carbon black based black paste is higher than 50%. For another example, the solid content of titanium dioxide based white paste, iron yellow paste and iron red paste based on iron oxide is higher than 75%.

[0064] In addition, according to the present application, the high solid low viscosity solvent based color paste has excellent flowability, and the viscosity is lower than 100 KU. To achieve the second object, the present application provides a method for preparing a high solid low viscosity color paste, comprising the steps of:

[0065] The dispersant and grinding resin are sequentially added to the first solvent, and stirred and mixed uniformly to obtain a clear solution. The pigment, synergistic agent and anti-settling agent are slowly added under stirring, and high-speed dispersion is performed to obtain a uniform mixture. Subsequently, sand milling is performed to make the fineness <10 μm, and the solid content is adjusted to prepare the high solid low viscosity color paste.

[0066] In one embodiment, the sand milling process is a dispersion process using grinding media. The equipment used can be a basket sand mill or a horizontal sand mill, and the sand milling media can use zirconium beads of different sizes.

[0067] To achieve the third object, the present application provides an application of the high solid low viscosity color paste in a coil polyester topcoat.

[0068] In one embodiment, the coil polyester topcoat is a polyester amino baking finish, wherein the polyester is a saturated polyester.

[0069] In an embodiment, the coil polyester finish comprises, by weight parts: 30-40 parts of saturated polyester resin A, 5-20 parts of flexible saturated polyester resin B, 3-10 parts of amino resin, 1-60 parts of color paste, 5-15 parts of second solvent, 0.1-0.5 parts of catalyst and 0.5-10 parts of auxiliary.

[0070] In an embodiment, the saturated polyester resin A has a number average molecular weight of 2000-3000, a PDI of 1.5-3.0, a hydroxyl value of 80-150 mgKOH / g, a mass solid content of 60-65%, and a viscosity of X-Z2.

[0071] In an embodiment, the flexible saturated polyester resin B has a number average molecular weight of 2500-3500, a PDI of 3.0-5.0, a hydroxyl value of 90-140 mgKOH / g, a mass solid content of 70-75%, and a viscosity of Z1-Z2.

[0072] In an embodiment, the amino resin is a melamine formaldehyde resin.

[0073] In an embodiment, the amino resin is selected from a methyl etherified amino resin or a butyl etherified amino resin.

[0074] In an embodiment, the amino resin is selected from one or a combination of Cymel 303, YP-5603, LUWIPAL 066, OS303-98. These resins are all methyl etherified amino resins.

[0075] In an embodiment, the catalyst is selected from one or a combination of methylbenzenesulfonic acid, dodecylbenzenesulfonic acid, dinonyl naphthalene sulfonic acid, dinonyl naphthalene disulfonic acid, or dodecylbenzenesulfonic acid amine.

[0076] In an embodiment, the auxiliary comprises one or a combination of defoaming agent, leveling agent, matting powder. The matting powder includes but is not limited to one or a combination of TYS-300, TYS-180, ED-40, ED-5.

[0077] Compared with the prior art, the technical solution provided by the present application has the following advantages:

[0078] 1. The high solid low viscosity color paste provided by the present application can be used to prepare a series of different color coil polyester finish products that meet the low VOC requirement (<420 g / L), and does not affect the application performance such as final coating film performance, chemical resistance, long-term durability, etc.

[0079] 2. The coiled polyester finish prepared by using the high solid low viscosity color paste provided by the present application also has the characteristics of high coating rate.

[0080] 3. The high solid low viscosity color paste provided by the present application has higher pigment concentration in the grinding section, so that the grinding efficiency is obviously improved, and the energy consumption of the grinding section is significantly reduced. DETAILED DESCRIPTION

[0081] The specific embodiments of the present application are described in detail below. However, the present application should not be understood as being limited to such embodiments described below, and the technical idea of the present application can be implemented in combination with other known technologies or other technologies having the same functions as those known technologies.

[0082] In addition, the terms "first", "second", "third", etc. are used only for the purpose of description, and should not be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second", etc. can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise specifically specified and limited.

[0083] In the present application, unless otherwise specifically specified and limited, the terms "mounting", "connection", "connecting", "fixing" and the like should be understood in a broad sense, for example, can be fixed connection, or detachable connection, or integral; can be mechanical connection, or electrical connection; can be directly connected, or indirectly connected through an intermediate medium; can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0084] Unless clearly indicated to the contrary, each aspect or embodiment defined herein can be combined with any other aspect or aspects or embodiment or embodiments. In particular, any indicated feature that is preferred or advantageous can be combined with any other indicated feature that is preferred or advantageous.

[0085] As used herein, for the production of flat and thin-walled metal components, such as automotive components and bodywork components, but also corresponding components from the field of equipment housings, facade panels, ceiling coverings or window profiles, a suitable metal sheet, such as a steel or aluminum sheet, is shaped by means of conventional techniques, such as punching and / or drilling. Larger metal components can be assembled by welding together a large number of individual parts. Frequently used as raw material for the production of such components is a long metal strip, which is produced by rolling the metal and, in order to store and to transport it more easily, is wound to form a roll, i.e. a coil.

[0086] As used herein, the term "colorant" or "colorant" refers to a colored concentrate obtained by adding pigments or dyes known in the art to a conventional carrier or vehicle. In embodiments of the present application, the colorant is water-based, preferably with low VOC. The colorant typically comprises one or more pigments or dyes, with pigments generally preferred over dyes for cost reasons.

[0087] As used herein, the term "topcoat" refers to a polymeric coating that includes pigments and can impart color to a surface, can refer to any coating, combination of coatings, or functionalized layer applied over one or more basecoat layers or another topcoat. The topcoat can or can not be the final coating applied to the surface of the substrate.

[0088] As used herein, the terms "applied on", "arranged on", "deposited on / over", "covered" mean applied, arranged, deposited, and covered on, respectively, but not necessarily in contact with the surface. For example, a coating "arranged on" a substrate does not exclude the presence of one or more other coatings of the same or different composition located between the formed coating and the substrate.

[0089] In order to make the present application clearer, further description will be made in connection with preferred embodiments. It should be apparent that the following description is only for the purpose of illustration and should not be used to limit the scope of the present application.

[0090] In the present embodiment, the dispersant is added in the colorant in an amount of 1-50% by weight, and the preferred amount of dispersant can be determined according to the specific type of pigment, particle size, specific surface area, or oil absorption, etc. in combination with the color development and dispersion stability of the colorant.

[0091] In the present embodiment, the synergistic agent is a pigment derivative, such as a phthalocyanine blue derivative and an azo pigment derivative. The synergistic agent can enhance the adsorption of the dispersant on the surface of the pigment, further improving the wetting and dispersion of the grinding resin and the dispersant on the pigment, to prepare a colorant with more excellent flowability.

[0092] The above-mentioned components and amounts of the colorant will affect the final coating properties of the colorant, not only affecting the VOC of the coating product, but also affecting the application performance and long-term durability of the coating film. In the present embodiment, by selecting specific raw material compositions and amounts, a colorant suitable for use in a polyester topcoat for a coil material and having high solid and low viscosity characteristics is obtained, which can be used to prepare a series of polyester topcoat products of different colors that meet the requirements of low VOC (<420 g / L) and application performance.

[0093] In one embodiment of the present application, the grinding resin is a saturated polyester with 78% solid content, a number average molecular weight of 2000, a PDI of 2.3, a hydroxyl value of 140 mgKOH / g, and a viscosity of X-Z1.

[0094] In one embodiment of the present application, the dispersant is Solsperse®-161 from Byk Chemie, which is a polyurethane type dispersant with a solubility parameter SP of 11.1, a number average molecular weight of 2603, a weight average molecular weight of 5145, and a PDI of 1.98.

[0095] In one embodiment of the present application, the synergist is Solsperse 5000 from Lubrizol, which is used in an amount of 0.5 parts.

[0096] In one embodiment of the present application, a method for preparing the high solid low viscosity color paste is provided, which comprises the following steps:

[0097] (1) Pre-dispersion: the dispersant and the grinding resin are sequentially added to the first solvent in a container of a high-speed mixer, and mixed uniformly to obtain a clear solution; under stirring, the pigment, the synergist, and the anti-settling agent are slowly added, and high-speed dispersion is performed to obtain a uniform mixture (linear speed of 14 m / s, dispersion time of 30 minutes);

[0098] (2) Sand milling: a horizontal sand mill (purchased from Nanjing Nanqi Labstar) is used, 1.2-1.4 mm zirconium beads are filled, and the filling rate is 70%; the pre-dispersed mixture is transferred to the horizontal sand mill for sand milling, the sand milling linear speed is 10 m / s, and sand milling is performed for different numbers of times according to the types of pigments until the fineness of the color paste is <10 μm; after sand milling, the material is discharged.

[0099] In one embodiment of the present application, the high solid low viscosity color paste as described above is applied in a coil polyester topcoat, and when the color paste is used in the coil polyester topcoat, it has good compatibility with other components in the coating, and the application performance of the prepared coating can meet the requirements, the VOC content is lower than 420 g / L, and the coating rate is increased by 10-20% compared with the control product.

[0100] Hereinafter, the technical solutions of the present application are described in combination with some specific embodiments, and in addition, all the parts and percentages are by weight unless otherwise specified. All the raw materials used are commercially available unless otherwise specified:

[0101] Preparation of the grinding resin

[0102] Example 1: Grinding Resin R1

[0103] ​In a 500ml reaction flask equipped with a stirrer, heating device, condenser, water separator, nitrogen inlet tube, 60 parts by weight of phthalic anhydride, 15 parts by weight of isophthalic acid, 22 parts by weight of adipic acid, 20 parts by weight of trimethylolpropane and 75 parts by weight of neopentyl glycol were heated in the reaction kettle under inert gas protection. When the temperature of the reaction kettle reached 120°C, the stirring was started. Then 0.03 parts by weight of organotin catalyst was added. The temperature of the material in the reaction kettle was controlled at 220-230°C. The reaction was carried out for 6 hours.

[0104] 6 parts by weight of xylene was added in the reaction kettle until the acid value of the material was <10KOHmg / g.

[0105] The reaction kettle was cooled to 150°C. After adding 35 parts by weight of diluent, the material was filtered. The ground resin R1 was obtained. The number average molecular weight was 2000, the PDI was 2.3, the hydroxyl value was 140mgKOH / g, the mass solid content was 78%, and the viscosity was X-Z1.

[0106] Example 2: Ground resin R2

[0107] In a 500ml reaction flask equipped with a stirrer, heating device, condenser, water separator, nitrogen inlet tube, 65 parts by weight of phthalic anhydride, 10 parts by weight of isophthalic acid, 16 parts by weight of adipic acid, 25 parts by weight of trimethylolpropane and 65 parts by weight of neopentyl glycol were heated in the reaction kettle under inert gas protection. When the temperature of the reaction kettle reached 120°C, the stirring was started. Then 0.03 parts by weight of organotin catalyst was added. The temperature of the material in the reaction kettle was controlled at 220-230°C. The reaction was carried out for 8 hours.

[0108] 6 parts by weight of xylene was added in the reaction kettle until the acid value of the material was <10KOHmg / g.

[0109] The reaction kettle was cooled to 150°C. After adding 38 parts by weight of diluent, the material was filtered. The ground resin R2 was obtained. The number average molecular weight was 2200, the PDI was 2.5, the hydroxyl value was 120mgKOH / g, the mass solid content was 75%, and the viscosity was X-Z1.

[0110] Preparation of the color paste

[0111] Example 3: White paste I

[0112] The preparation formula of white paste I is shown in Table 1 below:

[0113] Table 1 Preparation formula of white paste I

[0114]

[0115]

[0116] In a container of high speed mixer, add grinding resin (component B), dispersant (component C), first solvent (component D and E) in sequence, mix well to get clear liquid, under stirring, slowly add pigment (component A), anti-settling agent (component F), high speed dispersion to get uniform mixture (linear velocity is 14 m / s, dispersion for 30 minutes).

[0117] Use horizontal sand mill (purchased from Nanjing Nanqi Labstar), fill 1.2-1.4 mm zirconium beads, filling rate is 70%; transfer the pre-dispersed mixture to horizontal sand mill for sanding, sanding linear velocity is 10 m / s, sand for 1 time, color paste fineness <10 μm; discharge to get white paste I, pigment concentration is 60%, solid content is 84.0%, viscosity is 92 KU (25°C).

[0118] Example 4: Blue paste I

[0119] The preparation formula of blue paste I is shown in Table 2 as follows:

[0120] Table 2 Preparation formula of blue paste I

[0121]

[0122] In a container of high speed mixer, add grinding resin (component B), dispersant (component C), solvent (component D and E) in sequence, mix well to get clear liquid, under stirring, slowly add pigment (component A), synergist (component F), high speed dispersion to get uniform mixture (linear velocity is 14 m / s, dispersion for 30 minutes).

[0123] Use horizontal sand mill (purchased from Nanjing Nanqi Labstar), fill 1.2-1.4 mm zirconium beads, filling rate is 75%; transfer the pre-dispersed mixture to horizontal sand mill for sanding, sanding linear velocity is 10 m / s, sand for 3 times, color paste fineness <10 μm; discharge to get blue paste I, pigment concentration is 24%, solid content is 59.0%, viscosity is 85 KU (25°C).

[0124] Example 5: Black paste I

[0125] The preparation formula of black paste I is shown in Table 3 as follows:

[0126] Table 3 Preparation formula of black paste I

[0127]

[0128] In a container of high speed mixer, add grinding resin (component B), dispersant (component C), solvent (component D and E) in sequence, mix well to get a clear solution. Under stirring, slowly add pigment (component A), synergist (component F), and disperse at high speed to get a homogeneous mixture (linear velocity is 14 m / s, disperse for 30 minutes).

[0129] Use horizontal sand mill (purchased from Nanjing Nanqi Labstar), fill 1.2-1.4 mm zirconium beads, filling rate is 75%; transfer the pre-dispersed mixture to the horizontal sand mill for sanding, sanding linear velocity is 10 m / s, sand for 3 times, color paste fineness <10 μm; discharge to get black paste I, pigment concentration is 12%, solid content is 51.5%, viscosity is 83 KU (25°C).

[0130] Example 6: Iron yellow paste

[0131] The preparation formula of iron yellow paste is shown in Table 4.

[0132] Table 4 Preparation formula of iron yellow paste

[0133] Ingredients Raw materials Parts by weight A Bayferrox 3920 60.0 B Grinding resin R1 (prepared in example 1) 20.0 C Efka PU 4050 dispersant 6.0 D S-100 solvent 8.0 E PMA solvent 5.5 F AEROSIL R972 0.5

[0134] In a container of high speed mixer, add grinding resin (component B), dispersant (component C), solvent (component D and E) in sequence, mix well to get a clear solution. Under stirring, slowly add pigment (component A), anti-settling agent (component F), and disperse at high speed to get a homogeneous mixture (linear velocity is 14 m / s, disperse for 30 minutes).

[0135] Use horizontal sand mill (purchased from Nanjing Nanqi Labstar), fill 1.2-1.4 mm zirconium beads, filling rate is 70%; transfer the pre-dispersed mixture to the horizontal sand mill for sanding, sanding linear velocity is 10 m / s, sand for 3 times, color paste fineness <10 μm; discharge to get iron yellow paste, pigment concentration is 60%, solid content is 79.0%, viscosity is 95 KU (25°C).

[0136] Example 7: Iron red paste

[0137] The preparation formula of iron red paste is shown in Table 5.

[0138] Table 5 Preparation formula of iron red paste

[0139] Ingredients Raw materials Parts by weight A Bayferrox 4130 FM 60.0 B Grinding resin R1 (prepared in example 1) 20.0 C Efka PU 4010 dispersant 6.0 D S-100 solvent 8.0 E PMA solvent 5.5 F AEROSIL R972 0.5

[0140] In a container of high speed mixer, add grinding resin (component B), dispersant (component C), solvent (component D and E) in sequence, mix well to get clear solution, under stirring, slowly add pigment (component A), anti-settling agent (component F), high speed dispersion to get uniform mixture (linear velocity is 14 m / s, dispersion for 30 minutes).

[0141] Use horizontal sand mill (purchased from Nanjing Nanqi Labstar), fill 1.2-1.4 mm zirconium beads, filling rate is 70%; transfer the pre-dispersed mixture to horizontal sand mill for sanding, sanding linear velocity is 10 m / s, sand for 3 times, color paste fineness <10 μm; discharge to get iron red paste, pigment concentration is 60%, solid content is 79.0%, viscosity is 97 KU (25°C).

[0142] Example 8: Green paste

[0143] The preparation formula of green paste is shown in Table 6.

[0144] Table 6 Preparation formula of green paste

[0145]

[0146] In a container of high speed mixer, add grinding resin (component B), dispersant (component C), solvent (component D and E) in sequence, mix well to get clear solution, under stirring, slowly add pigment (component A), synergist (component F), high speed dispersion to get uniform mixture (linear velocity is 14 m / s, dispersion for 30 minutes).

[0147] Use horizontal sand mill (purchased from Nanjing Nanqi Labstar), fill 1.2-1.4 mm zirconium beads, filling rate is 75%; transfer the pre-dispersed mixture to horizontal sand mill for sanding, sanding linear velocity is 10 m / s, sand for 3 times, color paste fineness <10 μm; discharge to get green paste, pigment concentration is 20%, solid content is 57.0%, viscosity is 88 KU (25°C).

[0148] Example 9: DPP red paste

[0149] The preparation formula of DPP red paste is shown in Table 7.

[0150] Table 7 Preparation formula of DPP red paste

[0151] Ingredients Raw materials Parts by weight A Cinilex DPP Red SR1 C 25.0 B Grinding resin R1 (prepared in example 1) 35.0 C NUOSPERSE FX 9360 dispersant 18.0 D S-100 solvent 12.0 E PMA solvent 9.5 F Solsperse 22000 synergist 0.5

[0152] In a container of high speed mixer, add grinding resin (component B), dispersant (component C), solvent (component D and E) in sequence, mix well to get a clear solution, under stirring, slowly add pigment (component A), synergist (component F), high speed dispersion to get a homogeneous mixture (linear velocity is 14 m / s, dispersion for 30 minutes).

[0153] Use horizontal sand mill (purchased from Nanchi Labstar), fill 1.2-1.4 mm zirconium beads, filling rate is 75%; transfer the pre-dispersed mixture to horizontal sand mill for sanding, sanding linear velocity is 10 m / s, sand for 3 times, color paste fineness <10 μm; discharge to get DPP red paste, pigment concentration is 25%, solid content is 60.0%, viscosity is 90 KU (25°C).

[0154] Example 10: purple paste

[0155] The preparation formula of purple paste is shown in Table 8.

[0156] Table 8 Preparation formula of purple paste

[0157] Ingredients Raw materials Parts by weight A Cinquasia Violet L 5110 15.0 B Grinding resin R1 (prepared in example 1) 45.0 C Solsperse 32500 dispersant 15.0 D S-100 solvent 15.0 E PMA solvent 9.5 F Solsperse 5000 synergist 0.5

[0158] In a container of high speed mixer, add grinding resin (component B), dispersant (component C), solvent (component D and E) in sequence, mix well to get a clear solution, under stirring, slowly add pigment (component A), synergist (component F), high speed dispersion to get a homogeneous mixture (linear velocity is 14 m / s, dispersion for 30 minutes).

[0159] Use horizontal sand mill (purchased from Nanchi Labstar), fill 1.2-1.4 mm zirconium beads, filling rate is 75%; transfer the pre-dispersed mixture to horizontal sand mill for sanding, sanding linear velocity is 10 m / s, sand for 4 times, color paste fineness <10 μm; discharge to get purple paste, pigment concentration is 15%, solid content is 56.5%, viscosity is 92 KU (25°C).

[0160] Example 11: white paste II

[0161] Replace the grinding resin R1 in the formulation of Example 3 color paste with the same amount of grinding resin R2 synthesized in Example 2, and keep other conditions unchanged, to prepare white paste II, pigment concentration is 60%, solid content is 83.0%, viscosity is 94 KU (25°C).

[0162] Example 12: blue paste II

[0163] The grinding resin R1 in the color paste formulation of Example 4 was replaced by the grinding resin R2 synthesized in Example 2 in equal amount, and the rest of the conditions remained unchanged, to prepare a blue paste II, with a pigment concentration of 24%, a solid content of 59.0%, and a viscosity of 90 KU (25°C).

[0164] Example 13: Black Paste II

[0165] The grinding resin R1 in the color paste formulation of Example 5 was replaced by the grinding resin R2 synthesized in Example 2 in equal amount, and the rest of the conditions remained unchanged, to prepare a black paste II, with a pigment concentration of 12%, a solid content of 50.2%, and a viscosity of 88 KU (25°C).

[0166] Comparative Example 1

[0167] A commercially available PCM100 color paste system for coil polyester topcoat (purchased from PPG) was selected as Comparative Example 1, and was compared with the white paste I, the blue paste I, the black paste I, the iron yellow paste, the iron red paste, the DPP red paste, the green paste, and the purple paste.

[0168] The PCM100 color paste system was based on a medium solid content grinding resin R3, with a number average molecular weight of 2800, a PDI of 2.8, a hydroxyl value of 110 mgKOH / g, a mass solid content of 60%, and a viscosity of X-Z2.

[0169] Comparative Example 2

[0170] A cycloaliphatic polyester with a hydrophobic tail chain attached was synthesized according to the method disclosed in Example 1 of US 8969438 of Akzo Nobel, with a solid content of 65%, and was used to replace the grinding resin R1 in the color paste formulations of Examples 3-10 in equal solid content, and the rest of the conditions remained unchanged, to prepare the corresponding color pastes.

[0171] Comparative Example 3

[0172] Referring to Example 1, the amount of neopentyl glycol was adjusted from 75 parts to 70 parts, the temperature of the materials in the reaction kettle was controlled at 220-230°C for 10 hours, and the rest of the conditions remained unchanged, to prepare a grinding resin R4, with a number average molecular weight of 3100, a PDI of 2.8, a hydroxyl value of 60 mgKOH / g, a mass solid content of 68%, and a viscosity of X-Z2. The grinding resin R4 was used to replace the grinding resin R1 in the color paste formulations of Examples 3-10 in equal solid content, and the rest of the conditions remained unchanged, to prepare the corresponding color pastes, which were respectively the white paste C1, the blue paste C1, the black paste C1, the iron yellow paste C1, the iron red paste C1, the green paste C1, the DPP red paste C1, and the purple paste C1.

[0173] Comparative Example 4: Blue Paste C2

[0174] The dispersant in the color paste formulation of Example 4 was replaced by FA 4660 (fatty acid amide type dispersant), and the rest of the conditions remained unchanged, to produce blue paste C2.

[0175] Comparative Example 5: black paste C2

[0176] The dispersant in the color paste formulation of Example 5 was replaced by Solsperse 17000 (solubility parameter SP of 9.5), and the rest of the conditions remained unchanged, to produce black paste C2.

[0177] Comparative Example 6: green paste C2

[0178] The synergist Solsperse 5000 in the color paste formulation of Example 8 was replaced by solvent PMA, and the rest of the conditions remained unchanged, to produce green paste C2.

[0179] Comparative Example 7: DPP red paste C2

[0180] The synergist Solsperse 22000 in the color paste formulation of Example 9 was replaced by solvent PMA, and the rest of the conditions remained unchanged, to produce DPP red paste C2.

[0181] Application of the color pastes prepared in Examples 3-10 and Comparative Examples 1-7 in a coil polyester topcoat

[0182] Example 14

[0183] The color pastes prepared in Examples 3-10 and the color pastes of Comparative Example 1 were added to the coil polyester topcoat base system to prepare the corresponding single-color paints, and the viscosity was adjusted to 110-120 s (T-4 viscosity cup) with a diluent (S150 solvent oil / PMA = 3:1). The mechanical properties and application properties of the coating film were tested, as well as the VOC content and coating rate of the paint.

[0184] The coil polyester topcoat base formulation (not containing color paste) used included the following raw materials in parts by weight:

[0185]

[0186]

[0187] 100 parts of the above base were taken and 8 color pastes in Examples 3-10 were added respectively to prepare 8 single-color paints. Among them, the addition amount of white paste I was 90 g, that of blue paste I was 30 g, that of black paste I was 20 g, that of iron yellow paste was 50 g, that of iron red paste was 50 g, that of green paste was 40 g, that of DPP red paste was 50 g, and that of purple paste was 25 g. The corresponding color pastes in Comparative Example 1 were added according to the pigment concentration to obtain single-color paints with the same pigment concentration.

[0188] The test results are shown in Table 9 below:

[0189] Table 9 Comparison of color paste pigment concentration and viscosity

[0190]

[0191] The single color paints prepared by adding each color paste into the base material (adjusted to the same viscosity of 110-120 s with diluent, T-4 viscosity cup), paint VOC and coating rate are compared as shown in Table 10 below:

[0192] Table 10

[0193]

[0194]

[0195] The high solid low viscosity color paste of Examples 3-10 is suitable for coil polyester topcoat, and the film performance meets the requirements; compared with Comparative Example 1 (PCM100 color paste system), it has the following advantages:

[0196] 1) Higher pigment concentration and better grinding efficiency can reduce the energy required in the grinding production process.

[0197] 2) The single color paint prepared by using Examples 3-10 has higher solid content and lower VOC (<420 g / L).

[0198] 3) The single color paint prepared by using Examples 3-10 has higher coating rate, with an overall improvement of 10-15%.

[0199] Example 15:

[0200] Each color paste prepared by Examples 3-10 and the color pastes prepared by Comparative Example 2 and Comparative Example 3 are added to the coil polyester topcoat base material system to prepare the corresponding single color paint, and the viscosity is adjusted to 110-120 s (T-4 viscosity cup) with diluent (S150 solvent oil / PMA = 3:1); the VOC content and coating rate of the paint are tested. Among them, the selected coil polyester topcoat base material formula (not containing color paste) includes the following raw materials by weight:

[0201]

[0202] Take 100 parts of the above base material, add each color paste of Examples 3-10, Comparative Example 2 color paste and 8 color pastes of Comparative Example 3 to prepare single color paint; wherein the white paste is 90 g, the blue paste is 30 g, the black paste is 20 g, the iron yellow paste is 50 g, the iron red paste is 50 g, the green paste is 40 g, the DPP red paste is 50 g, and the purple paste is 25 g.

[0203] The test results are shown in Table 11 below.

[0204] Table 11 Comparison of color paste viscosity

[0205]

[0206]

[0207] The single color paints prepared by adding each color paste into the base material (adjusted to the same viscosity, 110-120 s, T-4 viscosity cup, with diluent), paint VOC, and coating rate are compared in Table 12 below.

[0208] Table 12

[0209]

[0210] Compared with each color paste of Comparative Example 2 and Comparative Example 3, each color paste of Examples 3-10 prepared using the ground resin R1 synthesized in Example 1 has better flowability (lower viscosity), the single color paint prepared by adding each color paste into the above-mentioned coil polyester topcoat base material has higher solid content, lower VOC (<420 g / L), and higher coating rate.

[0211] Comparison of monochromatic paint film properties

[0212] The film performance of the single color paints prepared by adding each color paste of Examples 3-10 into the base material is shown in Table 13 below.

[0213] Table 13

[0214]

[0215] In contrast, the film performance of the single color paints prepared by adding each color paste of Comparative Example 2 prepared using the alicyclic polyester into the base material is shown in Table 14 below.

[0216] Table 14

[0217]

[0218]

[0219] As shown in Tables 13 and 14 above, compared with each color paste of Comparative Example 2, the paint film containing each color paste of Examples 3-10 prepared using the ground resin R1 synthesized in Example 1 has better paint film mechanical properties and chemical resistance. Comparative Example 2 is a color paste prepared based on the alicyclic polyester synthesized by the method of Example 1 of US 8969438 patent, which cannot meet the requirements of the coil polyester topcoat system described in the present application, and the mechanical properties and chemical resistance of the paint film cannot meet the requirements.

[0220] Example 16

[0221] Each of the color pastes of Examples 4, 5, 8 and 9 and Comparative Examples 4, 5, 6 and 7 were added to the web polyester topcoat base system as described above to formulate the corresponding monochromatic paints and the viscosity was adjusted to 110-120 s (T-4 viscosity cup) with diluent (S150 solvent oil / PMA = 3:1). The VOC content and the coating rate of the paints were tested and are shown in Table 15 below.

[0222] Table 15

[0223]

[0224] In comparison to Example 4, the blue color paste prepared in Comparative Example 4 using The blue color paste prepared in Comparative Example 4 using FA 4660 (fatty acid amide type dispersant) has a higher viscosity, resulting in a lower solids, higher VOC and lower coating rate of the formulated paint.

[0225] Similarly, in comparison to Example 5, the black color paste prepared in Comparative Example 5 using Solsperse 17000 (solubility parameter SP of 9.5) has a higher viscosity, resulting in a lower solids, higher VOC and lower coating rate of the formulated paint.

[0226] Furthermore, in comparison to Examples 8 and 9, if the synergist is removed from the green and DPP red color paste formulations (i.e. Comparative Examples 6 and 7), the prepared color pastes have a higher viscosity, resulting in a lower solids, higher VOC and lower coating rate of the formulated paint.

[0227] It can be seen that the combined effect of the grinding resin and the dispersant prepared by the method of the present application or the combined effect of the grinding resin, the dispersant and the synergist prepared by the method of the present application can result in a color paste with high solids, low viscosity, low VOC and high coating rate.

[0228] Unless otherwise defined, all similar terms such as "first", "second" and the like in the description herein are not intended to refer to any particular order or sequence, but instead are intended to reflect relative importance of the various technical features. Similarly, the terms "about", "approximately" and the like in the description herein are intended to encompass amounts that would be expected to have little to no practical impact on the technical features. Also, unless otherwise defined, all terms used herein including technical terms, should be interpreted as having the same meaning as they would be interpreted by one skilled in the art. Also, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present technical solutions belong. The terms "include", "comprise", "comprising", "have", "having", "contain", "containing", "include", "including", "contain", "containing", "including" and the like are used herein in their open-ended, non-limiting sense, that is, they are used to mean "including, but not limited to".

[0229] The preferred embodiments described in the specification are only the preferred embodiments of the present application, and the above embodiments are only used to illustrate the technical solutions of the present application but not to limit the present application. Any technical solutions obtained by logical analysis, reasoning or limited experiments based on the concept of the present application should be within the scope of the present application.

Claims

1. A high solid low viscosity color paste consisting of the following components in parts by weight: 10-70 parts of pigments, 20-60 parts of grinding resin, 1-50 parts of dispersant, less than 2 parts of synergist, less than 3 parts of anti-settling agent and 5-40 parts of first solvent; The grinding resin is a high solid saturated polyester with high hydroxyl value, having the following characteristics: (1) the number average molecular weight is 1800-2200; (2) the PDI is 2.2-2.6; (3) the hydroxyl value is 120-140 mg KOH / g; (4) the mass solid content is 75-80%; and (5) the viscosity is X-Z2; The dispersant is selected from the group consisting of polyester type polymer dispersant, polyurethane type polymer dispersant and / or acrylate type polymer dispersant, wherein the dispersant has a solubility parameter SP of 10.0-13.0, a number average molecular weight of 2000-20000 and a PDI of 1.0-5.

0.

2. The high solid low viscosity colorant slurry according to claim 1, wherein The high solid low viscosity color paste comprises less than 1 part of synergist and less than 1 part of anti-settling agent.

3. The high solid low viscosity colorant slurry according to claim 1, wherein The pigments are organic and / or inorganic pigments.

4. The high solid low viscosity colorant slurry according to claim 1, wherein In the high solid low viscosity solvent type color paste, the dispersant has a solubility parameter SP of 10.5-12.5, a number average molecular weight of 2500-10000 and a PDI of 1.0-3.

0.

5. The high solid low viscosity colorant slurry of claim 1, wherein, In the high solid low viscosity solvent type color paste, the first solvent is selected from one or a combination of butyl acetate, S-150 solvent oil, S-100 solvent oil, mixed dibasic ester, xylene, propylene glycol methyl ether acetate, diacetone alcohol.

6. The high solid low viscosity colorant slurry of claim 1, wherein, In the high solid low viscosity solvent type color paste, the synergist is a pigment derivative.

7. The high solid low viscosity colorant slurry according to claim 6, wherein The synergist is a phthalocyanine blue derivative and an azo pigment derivative.

8. The high solid low viscosity colorant slurry according to claim 1, wherein The anti-settling agent is selected from one or a combination of fumed silica, hectorite clay and polyamide wax.

9. A method for preparing the high solid low viscosity color paste according to any one of claims 1-8, comprising the steps of: adding the dispersant and the grinding resin into the first solvent in sequence, stirring and mixing uniformly to obtain a clear solution; slowly adding the pigments, the synergist and the anti-settling agent under stirring, performing high speed dispersion to obtain a uniform mixture, then performing sand milling to make the fineness <10 μm, adjusting the solid content, and obtaining the high solid low viscosity color paste.

10. Use of the high solid low viscosity color paste according to any one of claims 1-8 in a coil polyester finish, wherein the coil polyester finish is a polyester amino baking finish.

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