High-stability pre-dispersed pigment color sheet and preparation method thereof

Abstract

The application provides a high-stability pre-dispersed pigment color sheet and a preparation method thereof, relates to the technical field of pigment color sheets, and is characterized in that the high-stability pre-dispersed pigment color sheet comprises the following components in parts by weight: pigment color powder 30-60 parts, carrier resin 30-55 parts, dispersant 3-10 parts, hydroxyl-terminated hyperbranched polyester 2-8 parts, pigment surface treatment agent 1-5 parts, stabilizer 0.5-3 parts, and solvent 5-15 parts. The preparation method of the high-stability pre-dispersed pigment color sheet comprises the following steps: mixing and plasticizing, grinding and dispersing, sheet drawing and crushing. The application has the following advantages: the color sheet has small color difference change in a long-term storage process, has high color retention, has excellent pigment dispersion effect, has strong adaptability to a high-end paint system, and has low solvent usage and good environmental protection in the preparation process.

Description

Technical Field

[0001] This invention relates to the field of pigment flake technology, and in particular to a highly stable pre-dispersed pigment flake suitable for high-end coatings and inks CAB systems and its preparation method. Background Technology

[0002] Predispersed pigment chips are solid flake colorants made by pre-dispersing pigments in a resin carrier. Compared with using pigment powder directly, they have significant advantages such as ease of use, high tinting strength, fineness, and no dust pollution. These chips are widely used in automotive coatings, 3C coatings, high-end industrial coatings, and printing inks, and are an indispensable coloring raw material in high-end coating formulations.

[0003] Currently, the main method for producing industrial color chips is the mixing method, which results in unsatisfactory pigment dispersion. Traditional mixing processes rely on mechanical shearing force to disperse pigments, but shearing alone is insufficient to completely break down pigment aggregates into primary particles. This necessitates additional grinding and dispersion processes before final application, impacting efficiency. Furthermore, the production process is not environmentally friendly, generating large amounts of pigment dust and organic solvent vapors, which pollute the environment, pose safety hazards, and waste raw materials. Existing dust removal and solvent recovery devices are inefficient and prone to issues such as filter bag sticking.

[0004] Furthermore, existing color chip products still face several technical challenges in application: insufficient storage stability, with color drift easily occurring during long-term storage, especially under high temperature and humidity conditions, where pigment particles agglomerate or flocculate, leading to decreased tinting strength and hue shift, affecting batch consistency of coatings and inks. Resin system compatibility limitations: Cellulose acetate butyrate (CAB) is an indispensable key resin in high-end coatings and inks due to its rapid solvent release, excellent leveling properties, and pigment wetting characteristics; however, CAB system color chips face the technical challenge of molecular weight matching during preparation. While CAB resins with excessively low molecular weights are beneficial for reducing system viscosity, they result in insufficient film hardness and abrasion resistance; excessively high molecular weights lead to difficulties in melt mixing and reduced pigment dispersion efficiency.

[0005] Therefore, there is an urgent need to provide a pre-dispersed pigment chip with excellent storage stability, tinting strength, dispersibility and environmental friendliness, as well as its preparation method, to solve the above-mentioned technical problems. Summary of the Invention

[0006] The purpose of this invention is to provide a highly stable pre-dispersed pigment flake and its preparation method, which solves the problems of insufficient storage stability, unsatisfactory pigment dispersion effect, limited compatibility of resin system, and poor environmental friendliness of production process in the prior art. The color flake has small color difference change, high coloring power retention rate, and good dispersibility during long-term storage, while the preparation process is environmentally friendly and has low emissions.

[0007] To achieve the above-mentioned objectives, the technical solution adopted by this invention is as follows:

[0008] A highly stable pre-dispersed pigment flake comprises the following components in parts by weight: 30-60 parts pigment powder, 30-55 parts carrier resin, 3-10 parts dispersant, 2-8 parts hydroxyl-terminated hyperbranched polyester, 1-5 parts pigment surface treatment agent, 0.5-3 parts stabilizer, and 5-15 parts solvent.

[0009] The carrier resin is a mixture of first cellulose acetate butyrate and second cellulose acetate butyrate, wherein the mass ratio of the first cellulose acetate butyrate to the second cellulose acetate butyrate is 1:0.8 to 1.6, the number average molecular weight of the first cellulose acetate butyrate is 15,000 to 25,000, and the number average molecular weight of the second cellulose acetate butyrate is 40,000 to 70,000.

[0010] The hydroxyl-terminated hyperbranched polyester has a hydroxyl value of 200-500 mgKOH / g and a number-average molecular weight of 1500-4000.

[0011] The pigment powder is an organic pigment powder or an inorganic pigment powder; the pigment surface treatment agent is an organic compound containing multiple hydroxyl or multiple carboxyl groups; the stabilizer is a hindered amine light stabilizer or a phosphite antioxidant.

[0012] Preferably, the dispersant is a polyester-type polymeric dispersant, and the number-average molecular weight of the dispersant is 3000 to 15000.

[0013] Preferably, the solvent is one or a mixture of alcohol solvents, ester solvents, or ketone solvents.

[0014] This invention also provides a method for preparing the above-mentioned highly stable pre-dispersed pigment chips, characterized by comprising the following steps:

[0015] S1. Mixing and Plasticizing: According to the formula, add pigment powder, carrier resin, dispersant, hydroxyl-terminated hyperbranched polyester, pigment surface treatment agent, stabilizer and solvent into a high-speed mixer and stir and mix at 30-60°C for 20-60 minutes to obtain a premixed material; then put the premixed material into a closed rubber mixing mill and plasticize it under pressure at 80-130°C for 0.5-2 hours to obtain a plasticized material;

[0016] S2. Grinding and dispersing: After cooling the plasticized material obtained in step S1 to 40-60°C, it is put into a three-roll mill for grinding and dispersing. The grinding temperature is controlled at 50-120°C, and the roller speed ratio is slow roller: medium roller: fast roller = 1:3:9. Grind 2-5 times until the pigment fineness reaches below 15μm to obtain the ground material.

[0017] S3. Sheet pulling and crushing: The ground material obtained in step S2 is pulled into thin sheets with a thickness of 0.2 to 1.0 mm by a sheet pulling machine, cooled and crushed to 20 to 100 mesh to obtain the high-stability pre-dispersed pigment sheet.

[0018] Preferably, the high-speed mixer in step S1 is equipped with a heating jacket, and an inert gas is introduced for protection during the mixing process.

[0019] Preferably, the temperature is controlled by circulating cooling water during the grinding process in step S2.

[0020] The beneficial effects of this invention are as follows:

[0021] 1. Significantly improved storage stability: This invention introduces terminal hydroxyl hyperbranched polyester, whose abundant terminal hydroxyl groups can form multi-point hydrogen bond adsorption with the pigment surface, effectively anchoring pigment particles and preventing them from agglomerating and flocculating during storage; at the same time, it forms intermolecular forces with the ester groups of CAB carrier resin, enabling the color chip system to form a stable three-dimensional network structure, thereby reducing color difference changes during long-term storage.

[0022] 2. Excellent pigment dispersion effect: This invention uses a blend of high molecular weight CAB and low molecular weight CAB as the carrier resin. The high molecular weight CAB provides film strength and wear resistance, while the low molecular weight CAB ensures that the system has a suitable low viscosity during melt processing. The synergistic effect of the two makes it easier for the pigment to be sheared and dispersed into the primary particle state during mixing and grinding, and the coloring power of the color flakes is significantly improved.

[0023] 3. Low solvent usage and good environmental performance: Through the synergistic wetting effect of terminal hydroxyl hyperbranched polyester and dispersant, the solvent usage is reduced without affecting the processing performance, thus reducing VOC emissions.

[0024] 4. Strong compatibility with high-end coating systems: The color chips of this invention use CAB as the main resin, which has good compatibility with commonly used coating film-forming substances such as nitrocellulose, acrylic resin, polyurethane resin, and melamine-formaldehyde resin. It is suitable for automotive coatings, 3C coatings and high-end ink systems, and can be used directly without significant adjustments to existing formulas. Detailed Implementation

[0025] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0026] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0027] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0028] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be obvious to those skilled in the art. This application specification and embodiments are merely exemplary.

[0029] Example 1

[0030] A highly stable pre-dispersed pigment chip comprises the following components in parts by weight: 40 parts phthalocyanine blue pigment, 20 parts cellulose acetate butyrate with a number average molecular weight of 18,000, 20 parts cellulose acetate butyrate with a number average molecular weight of 55,000, 6 parts polyester dispersant, 4 parts hydroxyl-terminated hyperbranched polyester, 3 parts pentaerythritol pigment surface treatment agent, 1.5 parts hindered amine stabilizer, and 10 parts propylene glycol methyl ether acetate.

[0031] Among them, the hydroxyl-terminated hyperbranched polyester has a hydroxyl value of 300 mg KOH / g and a number-average molecular weight of 2500.

[0032] A method for preparing highly stable pre-dispersed pigment chips includes the following steps:

[0033] S1. Put the above raw materials into a high-speed mixer and stir and mix at 50°C for 40 minutes;

[0034] S2. Put the premixed material into a closed rubber mixing mill and plasticize it at 110°C for 1 hour;

[0035] S3. After cooling to 50℃, grind three times in a three-roll mill with a roller speed ratio of 1:3:9 and temperature controlled at 90~100℃.

[0036] S4. The ground material is drawn into 0.5mm thin sheets by a sheet-pulling machine, cooled and pulverized to 60 mesh to obtain the color sheet product.

[0037] The performance of the color filters prepared in Example 1 was tested, and the results are as follows:

[0038] ΔE color difference value after 90 days of storage at 50℃: 0.9;

[0039] Coloring power (relative to standard): 98.5%;

[0040] Pigment fineness (scraper fineness gauge): 10μm;

[0041] Gloss of the paint film (60° angle): 92.3.

[0042] Example 2

[0043] A highly stable pre-dispersed pigment chip comprises the following components in parts by weight:

[0044] 50 parts of rutile titanium dioxide, 18 parts of cellulose acetate butyrate with a number average molecular weight of 20,000, 22 parts of cellulose acetate butyrate with a number average molecular weight of 60,000, 5 parts of polyether-type polymeric dispersant, 5 parts of hydroxyl-terminated hyperbranched polyester, 2 parts of citric acid pigment surface treatment agent, 1 part of phosphite antioxidant, and 8 parts of diacetone alcohol.

[0045] The hydroxyl-terminated hyperbranched polyester has a hydroxyl value of 350 mg KOH / g and a number-average molecular weight of 3000.

[0046] The preparation method of the highly stable pre-dispersed pigment chips is the same as in Example 1.

[0047] Performance test results:

[0048] ΔE color difference value after 90 days of storage at 50℃: 1.1;

[0049] Coloring power (relative to standard): 97.8%;

[0050] Pigment fineness: 12μm;

[0051] Gloss of the paint film (60° angle): 91.5.

[0052] Comparative Example 1

[0053] The only difference between this highly stable pre-dispersed pigment chip formulation and Example 1 is that it does not contain terminal hydroxyl hyperbranched polyester, and the preparation method is the same as that in Example 1.

[0054] Test results:

[0055] ΔE color difference value after 90 days of storage at 50℃: 2.8;

[0056] Coloring power (relative to standard): 92.3%;

[0057] Pigment fineness: 18μm.

[0058] Comparative Example 2

[0059] The only difference between this highly stable pre-dispersed pigment chip formulation and Example 1 is that it uses only a single cellulose acetate butyrate resin with a number average molecular weight of 38,000, and the preparation method is the same as in Example 1.

[0060] Test results:

[0061] ΔE color difference value after 90 days of storage at 50℃: 1.9;

[0062] Tinting strength (relative to standard): 94.1%;

[0063] Paint film hardness (pencil hardness): F.

[0064] The high-stability pre-dispersed pigment chips provided by this invention are widely used in automotive original equipment manufacturer (OEM) paints, automotive refinish paints, coatings for 3C electronic products, high-end wood coatings, and solvent-based inks. Their preparation method is mature, the equipment is versatile, and they are suitable for large-scale industrial production, resulting in significant economic and social benefits.

[0065] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A highly stable pre-dispersed pigment chip, characterized in that, The product comprises the following components in parts by weight: 30-60 parts pigment powder, 30-55 parts carrier resin, 3-10 parts dispersant, 2-8 parts hydroxyl-terminated hyperbranched polyester, 1-5 parts pigment surface treatment agent, 0.5-3 parts stabilizer, and 5-15 parts solvent. The carrier resin is a mixture of first cellulose acetate butyrate and second cellulose acetate butyrate, wherein the mass ratio of the first cellulose acetate butyrate to the second cellulose acetate butyrate is 1:0.8 to 1.6, the number average molecular weight of the first cellulose acetate butyrate is 15,000 to 25,000, and the number average molecular weight of the second cellulose acetate butyrate is 40,000 to 70,000.

2. The high-stability pre-dispersed pigment chip according to claim 1, characterized in that: The hydroxyl-terminated hyperbranched polyester has a hydroxyl value of 200–500 mg KOH / g and a number-average molecular weight of 1500–4000.

3. The high-stability pre-dispersed pigment chip according to claim 1, characterized in that, The dispersant is a polyester-type polymeric dispersant or a polyether-type polymeric dispersant, and the number-average molecular weight of the dispersant is 3000 to 15000.

4. The high-stability pre-dispersed pigment chip according to claim 1, characterized in that, The stabilizer is a hindered amine light stabilizer or a phosphite antioxidant.

5. The high-stability pre-dispersed pigment chip according to claim 1, characterized in that, The pigment surface treatment agent is an organic compound containing multiple hydroxyl or multiple carboxyl groups.

6. The method for preparing highly stable pre-dispersed pigment chips according to any one of claims 1-5, characterized in that, Includes the following steps: S1. Mixing and Plasticizing: Pigment powder, carrier resin, dispersant, hydroxyl-terminated hyperbranched polyester, pigment surface treatment agent, stabilizer, and solvent are mixed and then plasticized to obtain plasticized material. S2. Grinding and dispersing: The plasticized material is ground and dispersed to obtain ground material; S3. Sheet pulling and crushing: The ground material is pulled into sheets, cooled, and crushed to obtain the high-stability pre-dispersed pigment sheets.

7. The method for preparing a highly stable pre-dispersed pigment chip according to claim 6, characterized in that, In step S1, the mixing temperature is 30–60°C and the mixing time is 20–60 minutes; the plasticizing temperature is 80–130°C and the plasticizing time is 0.5–2 hours.

8. The method for preparing a highly stable pre-dispersed pigment chip according to claim 6, characterized in that, In step S2, a three-roll mill is used for grinding. The grinding temperature is 50-120℃, and the roller speed ratio of the three-roll mill is 1:3:

9. Grinding is performed 2-5 times until the pigment fineness reaches below 15μm.

9. The method for preparing a highly stable pre-dispersed pigment chip according to claim 6, characterized in that, In step S3, the thickness of the sheet pulled is 0.2 to 1.0 mm, and the particle size of the pulverized sheet is 20 to 100 mesh.

10. The high-stability pre-dispersed pigment chips according to any one of claims 1-5, characterized in that, Applications in automotive coatings, 3C coatings, high-end industrial coatings, or printing inks.