Modified titanium dioxide powder and its preparation method and water-based acrylic coatings

Abstract

This invention relates to the field of titanium dioxide modification technology for water-based coatings, specifically to modified titanium dioxide powder, its preparation method, and water-based acrylic coatings. The modified titanium dioxide powder provided by this invention is obtained from titanium dioxide, hydrogen-containing silicone oil, and terminal epoxy-terminated allyl polyether. The modified titanium dioxide powder provided by this invention exhibits good compatibility with water-based resins and high dispersibility and stability in water-based resins. Experiments show that the modified titanium dioxide provided by this invention has good dispersibility in water-based acrylic coatings, and its thermal storage stability at 50°C can reach a minimum of nearly 30 days, equivalent to one year of stable storage at room temperature with sealing, and a maximum of up to 45 days, equivalent to one and a half years of stable storage at room temperature with sealing.

Description

Technical Field

[0001] This invention relates to the field of titanium dioxide modification technology for water-based coatings, specifically to modified titanium dioxide powder, its preparation method, and water-based acrylic coatings. Background Technology

[0002] In recent years, people have placed increasing emphasis on sustainable development and environmental responsibility, proposing measures such as reducing VOC emissions and promoting eco-friendly alternatives. This has led to a surge in demand for waterborne coatings, primarily used in the automotive, consumer goods and home appliance, construction, and furniture industries. Among these, waterborne acrylic resins hold a significant share of the global waterborne coatings market due to their strength, stiffness, excellent solvent resistance, flexibility, impact resistance, and hardness. They are not only environmentally friendly alternatives, reducing paint odor and solvent usage, but also improve surface properties such as appearance, adhesion, and wetting, while providing corrosion resistance and scratch resistance.

[0003] In addition to environmental requirements, the application of water-based coatings also places strict demands on the additives, surfactants, and pigments within the coating. To reduce foaming and improve durability, the hydrophilicity of water-based coatings needs to be controlled to prevent excessive water absorption by the dry film, which would hinder drying. Simultaneously, high temperatures and low humidity cause rapid evaporation of moisture from the coating, especially in low-VOC formulations, affecting workability and application quality. Therefore, while ensuring good hydrophilicity of titanium dioxide used in water-based coatings, it is also crucial to maintain good dispersibility and stability within the water-based resin system. Summary of the Invention

[0004] In view of this, the technical problem to be solved by the present invention is to provide modified titanium dioxide powder and its preparation method and water-based acrylic coating. The modified titanium dioxide powder provided by the present invention has good compatibility with water-based resin and has high dispersibility and stability in water-based resin.

[0005] The present invention provides a modified titanium dioxide powder, which is obtained from titanium dioxide, hydrogen-containing silicone oil and terminal epoxy allyl polyether.

[0006] The hydrogen-containing silicone oil of this invention has a hydrogen content of 0.18% to 1.6%. Preferably, the hydrogen-containing silicone oil of this invention includes one or more of the following: a terminal low-hydrogen-content silicone oil with a hydrogen content of 0.18% to 0.5%, a side-chain low-hydrogen-content silicone oil with a hydrogen content of 0.18% to 0.5%, or a side-chain high-hydrogen-content silicone oil with a hydrogen content of 1.0% to 1.6%, with a side-chain high-hydrogen-content silicone oil having a hydrogen content of 1.6% being the most preferred. In some embodiments of this invention, the hydrogen-containing silicone oil is selected from type 202, type IOTA 203, type XY-202, and type XIAMETR. TM MHX-1107, viscosity 20 cst~50 cst.

[0007] The average molecular weight distribution of the terminal epoxy allyl polyether of the present invention is 500 g / mol to 2000 g / mol, preferably 500 g / mol to 1500 g / mol, more preferably 500 g / mol to 1200 g / mol; the double bond content of the terminal epoxy allyl polyether is 0.8% to 2.5%, preferably 0.8% to 2.1%, more preferably 0.9% to 2.08%; the epoxy value of the terminal epoxy allyl polyether is ≥0.8 eq / 1000g, preferably 0.8 eq / 1000g to 1.9 eq / 1000g. In some embodiments of the present invention, the terminal epoxy allyl polyether is selected from KL-11, KL-11B, KL-91B, and KL-986.

[0008] The molar ratio of silane in the hydrogen-containing silicone oil to the double bond in the terminal epoxy allyl polyether of the present invention is 1:(0.8~1.2), preferably 1:(1~1.2), and most preferably 1:1. At this ratio, the product conversion rate is the highest. Too little will lead to incomplete reaction of the hydrogen-containing silicone oil, while too much will pose a risk of generating by-products and product decomposition.

[0009] The titanium dioxide described in this invention is an inorganically coated titanium dioxide without organic treatment, and the particle size of the powder is not restricted. The titanium dioxide is a conventional, general-purpose titanium dioxide. In some embodiments of this invention, the titanium dioxide is pre-ground and pulverized to break up agglomerates, resulting in more uniform subsequent modification.

[0010] The modified titanium dioxide provided by this invention is obtained by modifying titanium dioxide with hydrogen-containing silicone oil and terminal epoxy allyl polyether as organic treatment agents, which can greatly improve the compatibility of titanium dioxide in water-based acrylic resin.

[0011] The present invention also provides a method for preparing any of the modified titanium dioxide powders described above, comprising the following steps:

[0012] S1) Under a protective gas atmosphere, hydrogen-containing silicone oil and terminal epoxy-terminated allyl polyether are reacted in the presence of a catalyst to obtain an epoxy-modified silicone oil compound.

[0013] S2) The titanium dioxide and the epoxy-modified silicone oil compound obtained in step S1) are subjected to steam powdering to obtain modified titanium dioxide powder.

[0014] This invention first reacts hydrogen-containing silicone oil and terminally epoxy-based allyl polyether in the presence of a catalyst under a protective gas atmosphere to obtain an epoxy-modified silicone oil compound. Specifically, under a protective gas atmosphere, the hydrogen-containing silicone oil and terminally epoxy-based allyl polyether are refluxed at the reaction temperature, and then a catalyst is added dropwise to allow for a continuous reaction, yielding the epoxy-modified silicone oil compound. The epoxy-modified silicone oil compound obtained by this invention is specifically a colorless, transparent, water-soluble epoxy-modified silicone oil compound.

[0015] The reaction system described in this invention contains only a small amount of solvent besides the catalyst, and no additional solvent is added, making it a solvent-free reaction. The reaction temperature is 80℃~120℃, preferably 100℃. As the reaction temperature gradually increases, the conversion rate shows a trend of first increasing sharply and then decreasing rapidly; excessively high temperatures can lead to product decomposition and the formation of byproducts. The reaction time is 6 h~10 h, preferably 7 h. Extending the reaction time beyond 7 hours does not significantly improve the conversion rate; in fact, it slightly decreases it.

[0016] The hydrogen-containing silicone oil and terminal epoxy-terminated allyl polyether described in this invention are the same as those described above and will not be repeated. The protective gas described in this invention is selected from one or more of nitrogen, helium, neon, or argon. The catalyst described in this invention is selected from platinum-based catalysts, preferably from one or more of Speier catalyst (isopropanol chloroplatinate) or Karstedt catalyst (platinum(O)-1,3-divinyl-1,1,3,3-tetramethyldisiloxane). The amount of the catalyst described in this invention, calculated as Pt, is 0.01% to 0.05% of the total mass of the hydrogen-containing silicone oil and the terminal epoxy-terminated allyl polyether, preferably 0.02%. In some embodiments of this invention, the catalyst is an isopropanol chloroplatinate solution, which is freshly prepared and used immediately. The mass ratio of chloroplatinate acid to isopropanol is 1:99. 100 mg of chloroplatinate acid is weighed into a flask, 9.9 g of isopropanol is added, and the mixture is stirred until a colorless and transparent solution is obtained, which is then sealed for later use.

[0017] In this invention, after obtaining the epoxy-modified silicone oil compound, titanium dioxide and the obtained epoxy-modified silicone oil compound are subjected to steam-powdering to obtain modified titanium dioxide powder. Specifically, the titanium dioxide is ground and pulverized, then the obtained epoxy-modified silicone oil compound is added to it, and the mixture is homogenized using a pulverizer, followed by steam-powdering to obtain modified titanium dioxide powder. The titanium dioxide described in this invention is the same as described above and will not be repeated.

[0018] The method for preparing modified titanium dioxide powder provided by this invention is simple. By adjusting the hydrophilic groups and proportions of hydrogen-containing silicone oil through terminal epoxy allyl polyether, the titanium dioxide powder can be modified, which can effectively achieve the compatibility and dispersibility of modified titanium dioxide powder in water-based acrylic resin.

[0019] This invention also provides the application of any of the modified titanium dioxide powders described above, or the modified titanium dioxide powders obtained by any of the preparation methods described above, in the preparation of water-based acrylic coatings. This invention uses hydrogen-containing silicone oil and terminal epoxy-terminated allyl polyether to polymerize a water-soluble silicone oil, and then uses the obtained water-soluble silicone oil to treat titanium dioxide powder. The treated titanium dioxide powder exhibits high dispersibility and stability in water-based acrylic resins. Its application in the production of titanium dioxide products can effectively improve the quality of titanium dioxide products and is expected to be used in powder coatings, especially in the preparation of water-based acrylic coatings. It can also be promoted to other titanium dioxide companies.

[0020] This invention provides modified titanium dioxide powder, its preparation method, and water-based acrylic coatings. The modified titanium dioxide powder provided by this invention is obtained from titanium dioxide, hydrogen-containing silicone oil, and terminal epoxy-terminated allyl polyether. The modified titanium dioxide powder provided by this invention exhibits good compatibility with water-based resins and high dispersibility and stability in water-based resins. Experiments show that the modified titanium dioxide provided by this invention has good dispersibility in water-based acrylic coatings, and its thermal storage stability at 50°C can reach a minimum of nearly 30 days, equivalent to one year of stable storage at room temperature with sealing, and a maximum of up to 45 days, equivalent to one and a half years of stable storage at room temperature with sealing. Detailed Implementation

[0021] This invention discloses modified titanium dioxide powder, its preparation method, and water-based acrylic coatings. Those skilled in the art can refer to the content of this document and appropriately modify the process parameters to achieve the desired results. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included in this invention. The methods and applications of this invention have been described through preferred embodiments, and those skilled in the art can clearly modify or appropriately change and combine the methods and applications described herein without departing from the content, spirit, and scope of this invention to realize and apply the technology of this invention.

[0022] The present invention will be further described below with reference to the embodiments:

[0023] Example 1

[0024] Hydrogen-containing silicone oil with side chains (IOTA 203, viscosity 50 cst, hydrogen content 0.18%) and terminal epoxy-terminated allyl polyether (KL-11B, average molecular weight distribution (530 g / mol), double bond content (1.73-2.08), epoxy value (≥1.7eq / 1000g)) were weighed in a round-bottom flask at a molar ratio of 1:1. A condenser was added, and a stir bar was used. After sealing, nitrogen was purged three times to remove air from the system. The system was then placed in an oil bath (the heat transfer medium was dimethyl silicone oil), heated to 100°C, refluxed, and the isopropanol chloroplatinate catalyst (catalyst dosage (based on Pt) was controlled at 0.02% of the total raw material mass) was added dropwise, and the reaction was continued for 7 hours. After the reaction was completed, the reaction system was cooled to room temperature, the solid was removed by filtration, and the low volatile substances were removed by rotary evaporation under reduced pressure. Finally, a colorless and transparent epoxy-modified water-soluble silicone oil compound 1# was obtained with a yield of 89%, an average molecular weight of 1619 g / mol, and a viscosity of 26 mPa·s.

[0025] Titanium dioxide powder with inorganic coating but no organic treatment was dried in an oven. 200 grams of the dried powder were then ground into powder. 1.0 gram of synthetic organic treatment agent #1 was added to the powder, and the mixture was thoroughly mixed using a pulverizer. This mixture was then subjected to steam treatment to obtain modified titanium dioxide. 100 grams of water-based acrylic resin and 5 grams of modified titanium dioxide were placed in a glass jar, along with 100 grams of glass beads. The jar was sealed and shaken for 30 minutes. After cooling to room temperature, a portion of the liquid was taken to test its dispersibility. The jar was then resealed and placed in a 50°C oven for heat storage. It was observed whether the resin and titanium dioxide separated into layers.

[0026] Example 2

[0027] Side-chain hydrogen-containing silicone oil (XY-202, viscosity 30 cst, hydrogen content 0.18%) and terminal epoxy-terminated allyl polyether (KL-986, average molecular weight distribution (1000 g / mol), double bond content (0.90-1.15), epoxy value (≥0.8 eq / 1000 g)) were weighed in a round-bottom flask at a molar ratio of 1:1. A condenser was added, and a stir bar was used. After sealing, nitrogen gas was purged three times to remove air from the system. The system was then placed in an oil bath (the heat transfer medium was dimethyl silicone oil), heated to 100°C, refluxed, and the isopropanol chloroplatinate catalyst (catalyst dosage (based on Pt) was controlled at 0.02% of the total raw material mass) was added dropwise, and the reaction was continued for 7 hours. After the reaction was completed, the reaction system was cooled to room temperature, the solid was removed by filtration, and the low volatile substances were removed by rotary evaporation under reduced pressure. Finally, a colorless and transparent epoxy-modified water-soluble silicone oil compound 2# was obtained with a yield of 88.5%, an average molecular weight of 2789 g / mol, and a viscosity of 37 mPa·s.

[0028] Titanium dioxide powder with inorganic coating but no organic treatment was dried in an oven. 200 grams of the dried powder were then ground. 1.0 gram of synthetic organic treatment agent #2 was added to the ground powder, and the mixture was thoroughly mixed using a grinder. This mixture was then subjected to steam grinding to obtain modified titanium dioxide. 100 grams of water-based acrylic resin and 5 grams of modified titanium dioxide were placed in a glass jar, along with 100 grams of glass beads. The jar was sealed and shaken for 30 minutes. After cooling to room temperature, a portion of the liquid was taken to test its dispersibility. The jar was then resealed and placed in a 50°C oven for heat storage. It was observed whether the resin and titanium dioxide separated into layers.

[0029] Example 3

[0030] Side-chain hydrogen-containing silicone oil (XIAMETR) TM MHX-1107 (viscosity 20 cst, hydrogen content 1.6%) and terminal epoxy-terminated allyl polyether (KL-11B, average molecular weight distribution (530 g / mol), double bond content (1.73-2.08), epoxy value (≥1.7 eq / 1000 g)) were weighed in a round-bottom flask at a molar ratio of 1:1. A condenser was added, and a stir bar was used. After sealing, nitrogen was purged three times to remove air from the system. The system was then placed in an oil bath (the heat transfer medium was dimethyl silicone oil), heated to 100°C, refluxed, and the isopropanol chloroplatinate catalyst (catalyst dosage (based on Pt) controlled at 0.02% of the total raw material mass) was added dropwise, and the reaction was continued for 7 hours. After the reaction was completed, the reaction system was cooled to room temperature, the solid was removed by filtration, and the low volatile substances were removed by rotary evaporation under reduced pressure. Finally, a colorless and transparent epoxy-modified water-soluble silicone oil compound 3# was obtained with a yield of 89%, an average molecular weight of 2436 g / mol, and a viscosity of 32 mPa·s.

[0031] Titanium dioxide powder with inorganic coating but no organic treatment was dried in an oven. 200 grams of the dried powder were then ground. 1.0 gram of synthetic organic treatment agent #3 was added to the ground powder, and the mixture was thoroughly mixed using a grinder. This mixture was then subjected to steam grinding to obtain modified titanium dioxide. 100 grams of water-based acrylic resin and 5 grams of modified titanium dioxide were placed in a glass jar, along with 100 grams of glass beads. The jar was sealed and shaken for 30 minutes. After cooling to room temperature, a portion of the liquid was taken to test its dispersibility. The jar was then resealed and placed in a 50°C oven for heat storage. It was observed whether the resin and titanium dioxide separated into layers.

[0032] Example 4

[0033] Side-chain hydrogen-containing silicone oil (XIAMETRTM MHX-1107, viscosity 30 cst, hydrogen content 1.6%) and terminal epoxy-terminated allyl polyether (KL-986, average molecular weight distribution (1000 g / mol), double bond content (0.90-1.15), epoxy value (≥0.8 eq / 1000 g)) were weighed in a round-bottom flask at a molar ratio of 1:1. A condenser was added, and a stir bar was used. After sealing, nitrogen gas was purged three times to remove air from the system. The system was then placed in an oil bath (the heat transfer medium was dimethyl silicone oil), heated to 100°C, refluxed, and the isopropanol chloroplatinate catalyst (catalyst dosage (based on Pt) was controlled at 0.02% of the total raw material mass) was added dropwise, and the reaction was continued for 7 hours. After the reaction was completed, the reaction system was cooled to room temperature, the solid was removed by filtration, and the low volatile substances were removed by rotary evaporation under reduced pressure. Finally, a colorless and transparent epoxy-modified water-soluble silicone oil compound 4# was obtained with a yield of 89%, an average molecular weight of 3589 g / mol, and a viscosity of 46 mPa·s.

[0034] Titanium dioxide powder with inorganic coating but no organic treatment was dried in an oven. 200 grams of the dried powder were then ground. 1.0 gram of synthetic organic treatment agent #4 was added to the ground powder, and the mixture was thoroughly mixed using a grinder. This mixture was then subjected to steam grinding to obtain modified titanium dioxide. 100 grams of water-based acrylic resin and 5 grams of modified titanium dioxide were placed in a glass jar, along with 100 grams of glass beads. The jar was sealed and shaken for 30 minutes. After cooling to room temperature, a portion of the liquid was taken to test its dispersibility. The jar was then resealed and placed in a 50°C oven for heat storage. It was observed whether the resin and titanium dioxide separated into layers.

[0035] The above observation of whether the resin and titanium dioxide are separated into layers specifically involves: observing their state at regular intervals every day to see if there is skinning, clumping, gelation, whether the pigment floats, settles, or flocculates (particle agglomeration), and whether the color is consistent throughout without separation.

[0036] The test results are shown in Table 1:

[0037] Table 1

[0038]

[0039] One day at 50℃ is approximately equivalent to seven days at room temperature. As shown in Table 1, organic treatment agents 1# and 2# show no significant change within 30 days at 50℃, but not within 45 days; organic treatment agents 3# and 4# show no change within 45 days, but not within 60 days. This indicates that titanium dioxide powder coated with water-soluble silicone oil achieves good dispersibility. However, during thermal storage, significant differences arise between water-soluble silicone oils of different molecular weights. With prolonged storage, the compatibility of water-soluble silicone oil prepared with low-hydrogen-content silicone oil deteriorates, leading to powder separation from the resin. High-hydrogen-content silicone oil, on the other hand, can graft more hydrophilic polyether segments, increasing the compatibility of the powder in the aqueous acrylic system and contributing to system stability. This difference provides new ideas and directions for subsequent product classification and performance optimization.

[0040] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. Modified titanium dioxide powder, characterized in that, It is made from titanium dioxide, hydrogen-containing silicone oil and terminal epoxy-terminated allyl polyether.

2. The modified titanium dioxide powder according to claim 1, characterized in that, The hydrogen content of the hydrogen-containing silicone oil is 0.18% to 1.6%.

3. The modified titanium dioxide powder according to claim 1, characterized in that, The hydrogen-containing silicone oil includes one or more of the following: terminal low-hydrogen-content silicone oil with a hydrogen content of 0.18% to 0.5%, side-chain low-hydrogen-content silicone oil with a hydrogen content of 0.18% to 0.5%, or side-chain high-hydrogen-content silicone oil with a hydrogen content of 1.0% to 1.6%.

4. The modified titanium dioxide powder according to claim 1, characterized in that, The average molecular weight distribution of the terminal epoxy allyl polyether is 500 g / mol to 2000 g / mol; The double bond content of the terminal epoxy allyl polyether is 0.8%~2.5%; The epoxy value of the terminal epoxy allyl polyether is ≥0.8 eq / 1000g.

5. The modified titanium dioxide powder according to claim 1, characterized in that, The molar ratio of silane in the hydrogen-containing silicone oil to the double bond in the terminal epoxy allyl polyether is 1:(0.8~1.2).

6. The modified titanium dioxide powder according to claim 1, characterized in that, The titanium dioxide is inorganically coated and has not undergone organic treatment.

7. The method for preparing the modified titanium dioxide powder according to any one of claims 1 to 6, characterized in that, Includes the following steps: S1) Under a protective gas atmosphere, hydrogen-containing silicone oil and terminal epoxy-terminated allyl polyether are reacted in the presence of a catalyst to obtain an epoxy-modified silicone oil compound. S2) The titanium dioxide and the epoxy-modified silicone oil compound obtained in step S1) are subjected to steam powdering to obtain modified titanium dioxide powder.

8. The preparation method according to claim 1, characterized in that, In step S1), the reaction temperature is 80℃~120℃, and the reaction time is 6 h~10 h.

9. The preparation method according to claim 1, characterized in that, In step S1), the catalyst is selected from platinum-based catalysts, and the amount of the catalyst, calculated as Pt, is 0.01% to 0.05% of the total mass of the hydrogen-containing silicone oil and the terminal epoxy allyl polyether.

10. The use of the modified titanium dioxide powder according to any one of claims 1 to 6 or the modified titanium dioxide obtained by any one of the preparation methods according to claims 7 to 9 in the preparation of waterborne acrylic coatings.

Images