Pigment yellow 83 for rubber products and preparation method of pigment yellow 83

Abstract

The invention belongs to the technical field of pigment preparation, and particularly relates to pigment yellow 83 for rubber products and a preparation method thereof, and the preparation method comprises the steps of diazo liquid preparation, coupling liquid preparation and coupling reaction. Wherein after the coupling reaction, the pigment strengthening step is carried out, a mobility improver is added into the reaction liquid for treatment, and the mobility improver is one or a mixture of more of polycarboxylate, a polyether block copolymer or a siloxane modified polymer. By adding the mobility improver, the mobility resistance of the pigment yellow 83 in a rubber product is remarkably improved, especially the pigment yellow 83 has excellent performance in a soft rubber product, and the mobility of the pigment yellow 83 is effectively controlled even under the condition of high temperature or high plasticizer content. And the phenomena of spots, stripes or color fading on the surface or in the product are avoided.

Description

Technical Field

[0001] The present invention belongs to the technical field of pigment preparation, and particularly relates to a Pigment Yellow 83 for rubber products and a preparation method thereof. Background Art

[0002] Pigment Yellow 83 is a high-performance organic pigment widely used in fields such as plastics, coatings, and inks. Its chemical structure is a bisazo pigment, which has excellent lightfastness, heat resistance, and vivid color, so it is highly favored in many industrial applications. However, although Pigment Yellow 83 performs well in many aspects, its dispersibility in plastics has always been one of the key factors restricting its application effect in plastics.

[0003] Currently, the preparation method of Pigment Yellow 83 is to separately prepare the diazo component and the coupling component, and then obtain it through the coupling reaction of the two. For example, Chinese Patent Application CN110511592A discloses a preparation method of Pigment Yellow 83. In this technology, the coupling reaction is carried out by strictly controlling parameters to precipitate uniform particles, and a surfactant is added to obtain Pigment Yellow 83 particles with better stability and compatibility.

[0004] When the Pigment Yellow 83 prepared by the above method is used in rubber products, its migration resistance is insufficient, and the migration is particularly obvious if the rubber undergoes temperature changes during use.

[0005] Therefore, there is an urgent need to provide a Pigment Yellow 83 with migration resistance in rubber products. Summary of the Invention

[0006] The purpose of the present invention is to provide a Pigment Yellow 83 for rubber products and a preparation method thereof to solve the problem that Pigment Yellow 83 is prone to migration in rubber products in the prior art.

[0007] The present invention adopts the following technical solutions: A preparation method of Pigment Yellow 83 for rubber products, comprising the following steps: S1. Preparation of diazo solution: Mix 3,3′-dichlorobenzidine and hydrochloric acid, stir until completely dissolved; cool down to T≤3°C, add sodium nitrite solution, carry out diazotization reaction, and filter after the reaction ends to obtain the diazo solution.

[0008] S2. Preparation of coupling solution: Add 2,5-dimethoxy-4-chloroacetoacetanilide to sodium hydroxide solution, stir until completely dissolved, add acetic acid solution, fully stir and adjust the pH to 6-8 to obtain the coupling solution; S3. Coupling reaction: Heat the coupling solution to 15 to 25°C, dropwise add the diazo solution, stir, and keep warm to carry out the coupling reaction to obtain the reaction solution; S4. Pigment strengthening: A migration promoter is added to the reaction solution for treatment, and the treated mixture is filtered, dried, and ground to obtain Pigment Yellow 83; The migration promoter is one or a mixture of polycarboxylates, polyether block copolymers, or silicone-modified polymers.

[0009] Under normal circumstances, the migration resistance of Pigment Yellow 83 is relatively stable. However, in rubber products, its migration resistance is insufficient and cannot meet the requirements of some high-quality products. Especially when the rubber experiences temperature changes during use, the migration is particularly obvious, with spots and stripes appearing on the surface or inside of the product, and the color fading or even turning white in some areas. This phenomenon is more significant in soft rubber products or products with a large amount of Pigment Yellow 83 added.

[0010] In soft rubber products, such as products made of nitrile rubber NBR, soft PVC, thermoplastic elastomer TPE, polyurethane rubber TPU, etc., usually during the preparation process, a relatively large amount of plasticizer needs to be added to reduce the hardness and rigidity of the rubber and improve its flexibility and processing performance. The inventor speculates that it may be due to the large content of plasticizer, which affects the migration of Pigment Yellow 83.

[0011] In the above solution, by optimizing the preparation process of Pigment Yellow 83, the migration of Pigment Yellow 83 is improved, making its migration stable in rubber products. Even in soft rubber, it can resist migration. Specifically, in the above optimization solution, after the coupling reaction is completed, a migration promoter is added to the reaction solution, and the pigment is modified with the migration promoter, resulting in a significant improvement in migration resistance.

[0012] Preferably, based on the mass of 3,3′-dichlorobenzidine, the addition amount of the migration promoter is 1.5 - 5%. During the adjustment of the addition amount of the migration promoter, it is found that if it is too low, the expected effect cannot be achieved; if it is too high, although the migration resistance is improved, it is found that the coloring power of Pigment Yellow 83 decreases. In this solution, by optimizing the addition amount of the migration promoter within the range of 1.5 - 5%, Pigment Yellow 83 has good migration resistance and coloring power, and excellent comprehensive performance.

[0013] Preferably, the migration promoter is polycarboxylate. It is found through experiments that when polycarboxylate is used, the improvement effect of migration is more significant, and the impact on other properties of Pigment Yellow 83 is smaller.

[0014] Preferably, before mixing 3,3′-dichlorobenzidine with hydrochloric acid, it is first treated with an alcohol solution for infiltration.

[0015] In this solution, through the infiltration treatment with an alcohol solution, it can assist the pigment strengthening step to achieve higher migration resistance of Pigment Yellow 83.

[0016] Preferably, the alcohol solution is an ethanol solution.

[0017] Preferably, the volume concentration of the ethanol solution is 65 to 80%.

[0018] Preferably, in step S4, the strengthening conditions for pigment strengthening are: temperature 40 to 60 °C, pressure 0.5 to 1.2 MPa.

[0019] Preferably, the pigment yellow 83 obtained in step S4 is refined, and the refining steps are as follows: A. Disperse the pigment yellow 83 in a pigment emulsifier to form a pigment emulsion; B. Control the pigment emulsion to reach the freezing point of the pigment emulsion and below to obtain a frozen pigment emulsion; C. Crush, ball mill, and dry the frozen pigment emulsion with an ultrasonic crusher to obtain refined pigment yellow 83.

[0020] In the above solution, the pigment yellow 83 is refined. Among them, in step A, the emulsifier not only helps the pigment yellow 83 to form a liquid emulsion state for the subsequent steps, but also forms a coating layer on the surface of the pigment, which can improve the compatibility between the pigment and the matrix and enhance the migration resistance of the pigment. In steps B and C, by making the emulsion reach the freezing point and below, combined with subsequent crushing, ball milling, and drying treatments, the particle size of the pigment particles is significantly reduced. Smaller particles are more difficult to move in the rubber matrix, thereby reducing the migration tendency of the pigment during processing and use.

[0021] Preferably, in step B, control the temperature of the pigment emulsion to gradually decrease to reach the freezing point of the pigment emulsion and below, and make the emulsion reach the freezing point and below through a multi-stage temperature gradient of gradual decrease. This gentle cooling process can avoid the agglomeration of pigment particles during rapid cooling, thereby further improving the migration resistance of the pigment.

[0022] The present invention also provides a pigment yellow 83 obtained by the above preparation method.

[0023] By implementing the above technical solutions, the pigment yellow 83 obtained by the present invention has the following advantages: 1. Significantly improved migration resistance: In the present invention, by adding a migration enhancer, the migration resistance of pigment yellow 83 in rubber products is significantly improved, especially excellent in soft rubber products. Even under conditions of high temperature or high plasticizer content, the migration of pigment yellow 83 is effectively controlled, avoiding the appearance of spots, stripes, or color fading on the surface or inside of the product.

[0024] By pre-wetting 3,3′-dichlorobenzidine with an ethanol solution and refining Pigment Yellow 83, the migration property of Pigment Yellow 83 is further improved.

[0025] 2. Good coloring power retention: While improving the migration resistance of the present invention, the coloring power of Pigment Yellow 83 is not significantly affected, and the comprehensive performance is excellent. Detailed implementation manners

[0026] The present invention will be further described in detail below with reference to specific embodiments.

[0027] This specific embodiment is only an interpretation of the present invention and does not limit the present invention. After reading this specification, those skilled in the art can make modifications to this embodiment without creative contributions as needed, but as long as it is within the scope of the claims of the present invention, it is protected by the patent law.

[0028] Example 1 This example provides a preparation method of Pigment Yellow 83 for rubber products, including the following steps: S1. Preparation of diazo solution: Add 100 g of 3,3′-dichlorobenzidine and 200 mL of hydrochloric acid (concentration 36%) to an appropriate amount of water, make a slurry at room temperature and let it stand overnight; cool the slurry to 1 °C, slowly add a sodium nitrite solution (42 g dissolved in 100 mL of water), carry out a diazotization reaction for 50 min under a heat preservation condition, after the reaction ends, add activated carbon for decolorization and filtration to obtain a diazo solution for standby.

[0029] S2. Preparation of coupling solution: Mix 22 g of NaOH, 650 mL of deionized water and 120 g of 2,5-dimethoxy-4-chlorodiacetylaniline, stir for 15 min, then add 80 g of sodium acetate, after fully stirring, slowly add acetic acid solution until pH = 6, and stir evenly to form a coupling solution.

[0030] S3. Coupling reaction: Slowly add the diazo solution in step S1 to the coupling solution in step S2 at 10 °C within 1 hour for a coupling reaction. When the pH drops to pH = 5, stop the coupling, raise the temperature to 95 °C, and continue to keep warm for 60 min to obtain a reaction solution.

[0031] S4. Pigment strengthening treatment: Add 3 g of polycarboxylate (the addition amount is 3% based on the mass of 3,3′-dichlorobenzidine) to the reaction solution. Stir and treat at 50 °C and 0.8 MPa for 1 hour. Filter the treated mixture, collect the solid product, and dry it at 60 °C for 12 hours to obtain Pigment Yellow 83.

[0032] Example 2 This embodiment provides a method for preparing Pigment Yellow 83 for rubber products, which is different from that of Embodiment 1. In step S1, 3,3'-dichlorobenzidine is infiltrated with a 65% ethanol solution, including the following steps: S1. Preparation of diazo solution: 100 g of 3,3'-dichlorobenzidine is infiltrated with 500 mL of ethanol solution (65%) for half an hour, then filtered and dried. The dried 3,3'-dichlorobenzidine and 200 mL of hydrochloric acid (concentration 36%) are added to an appropriate amount of water, and slurried at room temperature and left standing overnight. The slurry is cooled to 1 °C, and a sodium nitrite solution (42 g dissolved in 100 mL of water) is slowly added, and the diazotization reaction is carried out for 50 min under heat preservation conditions. After the reaction is completed, activated carbon is added for decolorization and filtration to obtain the diazo solution for standby.

[0033] The remaining steps are the same as those in Embodiment 1.

[0034] Embodiment 3 This embodiment provides a method for preparing Pigment Yellow 83 for rubber products, which is different from that of Embodiment 1. After step S4, Pigment Yellow 83 is subjected to a refining treatment, and the refining steps are as follows: A. Disperse Pigment Yellow 83 in an aqueous solution of sodium stearate (mass-volume ratio of Pigment Yellow 83 to aqueous solution of sodium stearate is 1:3) to form a pigment emulsion; B. Quick-freeze the pigment emulsion with liquid nitrogen to obtain a freeze-dried pigment emulsion; C. Crush, ball-mill and dry the frozen pigment emulsion with an ultrasonic crusher (frequency 40 kHz, process for 10 s, interval 10 s, total processing time 20 min) to obtain refined Pigment Yellow 83.

[0035] Embodiment 4 This embodiment provides a method for preparing Pigment Yellow 83 for rubber products, which is different from that of Embodiment 5. In the refining treatment step, in step B, the temperature of the pigment emulsion is controlled to decrease in three stages until it reaches below the freezing point of the pigment emulsion (the first stage is maintained at 10 °C for 30 min, the cooling rate is 3 °C / min to the second stage of 3 °C and maintained for 30 min, and the cooling rate is 3 °C / min to the third stage of minus 5 °C). During this period, the pigment emulsion is stirred at a speed of 150 rpm until the pigment emulsion is completely frozen.

[0036] Comparative Example 1 This comparative example provides a method for preparing Pigment Yellow 83 for rubber products, which is different from that of Embodiment 1. The pigment strengthening treatment in step S4 is not carried out, and the reaction solution obtained in step S3 is directly filtered, the solid product is collected, and dried at 60 °C for 12 hours to obtain Pigment Yellow 83.

[0037] The obtained Pigment Yellow 83 of Examples 1-4 and Comparative Example 1 was tested for migration resistance and coloring power performance. The test methods and results are as follows.

[0038] Migration resistance: GB / T 5211.5-2008.

[0039] Relative coloring power: GB / T 13451.2-1992.

[0040] Table 1 Pigment Yellow 83 obtained from Examples 1-4 and Comparative Example 1 As can be seen from Table 1, for Examples 1-4 in the present invention, compared with Comparative Example 1 without the pigment strengthening step, they showed relatively excellent migration resistance and more excellent coloring power. Compared with Example 1, Example 2 adopted the infiltration operation on 3,3'-dichlorobenzidine. On the premise of ensuring high migration resistance, its coloring power was improved to a certain extent. Compared with Example 1, Examples 3 and 4 carried out specific refining treatment on Pigment Yellow 83. On the premise of ensuring high migration resistance, its coloring power was improved to a certain extent. Especially for the scheme of Example 4, the improvement of coloring power was more obvious.

[0041] Example 5 Based on the preparation method disclosed in Example 1, this example studied the influence of the addition amount of polycarboxylate on the performance of Pigment Yellow 83. The difference from Example 1 was the different addition amounts of polycarboxylate. Different gradients of addition amounts were set in this example: 0.5 g (0.5%), 1 g (1%), 1.5 g (1.5%), 2 g (2%), 2.5 g (2.5%), 3 g (3%), 3.5 g (3.5%), 4 g (4%), 4.5 g (4.5%), 5 g (5%), 5.5 g (5.5%), 6 g (6%).

[0042] The obtained Pigment Yellow 83 was tested for migration resistance and coloring power performance. The test results are as follows.

[0043] Table 2 Performance of Pigment Yellow 83 corresponding to migration improvers with different addition amounts As can be seen from Table 2, migration improvers with different addition amounts had different effects on the performance of Pigment Yellow 83. When the addition amount was below 1.5%, the migration resistance could not be improved. When it was above 1.5%, the migration resistance could reach more than level 4. However, when it exceeded 5%, there were certain side effects and the coloring power was affected. Therefore, the preferred addition amount of the migration improver in the present invention was between 1.5% and 5%.

[0044] Example 6 Based on the preparation method disclosed in Example 1, this example studies the influence of the selection of migration improvers on the performance of Pigment Yellow 83. Polycarboxylate dispersant, propylene glycol block polyether, silicone polycarbonate, polyurethane, PET, PP.

[0045] The migration resistance and coloring power of each Pigment Yellow 83 were detected. The test results are as follows.

[0046] Table 3 Performance of Pigment Yellow 83 corresponding to different migration improvers As can be seen from Table 3, different migration improvers have different effects on the performance of Pigment Yellow 83. Among the several selected in this example, polycarboxylate dispersant, propylene glycol block polyether, and silicone polycarbonate are relatively excellent in terms of migration resistance and coloring power.

[0047] Application Example 1 The Pigment Yellow 83 products obtained in Examples 1-4 and Comparative Example 1 were used in soft rubber products to detect the migration resistance and coloring power of each Pigment Yellow 83.

[0048] Weigh each component according to the following formula ratio: Nitrile rubber (NBR): 100 parts, Pigment Yellow 83: 5 parts, plasticizer (DOP): 10 parts, vulcanizing agent (sulfur): 2 parts, filler (calcium carbonate): 5 parts.

[0049] Mixing and molding: Use a mixer to uniformly disperse Pigment Yellow 83, plasticizer and other additives into nitrile rubber.

[0050] Vulcanize and mold the mixed rubber material to prepare standard specimens with consistent specifications.

[0051] Performance testing: Migration resistance test: Place the molded rubber specimen in a heat aging oven, set the temperature to 80 °C, and keep it for 48 hours. Observe the color change of the specimen surface.

[0052] The test results are as follows.

[0053] Table 4 Migration resistance of Pigment Yellow 83 in soft rubber products Combining the two sets of data in Example 1, the test data of GB / T 5211.5-2008 (using PVC as the base material) for migration resistance and the test data of this application example (using nitrile rubber as the base material) for migration resistance, it can be seen by comparison that for the solution in Comparative Example 1, although the migration resistance can reach Grade 4 in the PVC base material, it can only reach Grade 2 in the nitrile rubber base material. The migration resistance of Pigment Yellow 83 in Example 1 also decreased by one grade in nitrile rubber, while the migration resistance of Pigment Yellow 83 in Examples 2-3 can be maintained at the highest grade of 5.

[0054] Application Example 2 Different from Application Example 1, the usage amount of plasticizer in the rubber product is increased, and each component is weighed according to the following formulation ratio: Nitrile rubber (NBR): 100 parts, Pigment Yellow 83: 5 parts, Plasticizer (DOP): 30 parts, Vulcanizing agent (sulfur): 2 parts, Filler (calcium carbonate): 5 parts.

[0055] The test results of migration resistance are as follows.

[0056] Table 5 Migration resistance of Pigment Yellow 83 in soft rubber products Combining the two sets of data in Example 1, the test data of GB / T 5211.5-2008 (using PVC as the base material) for migration resistance and the test data of this application example (using nitrile rubber as the base material) for migration resistance, it can be seen by comparison that for the solution in Comparative Example 1, although the migration resistance can reach Grade 4 in the PVC base material, it can only reach Grade 1 in the nitrile rubber base material. The migration resistance of Pigment Yellow 83 in Examples 1 and 2 also decreased by one grade in nitrile rubber, while the migration resistance of Pigment Yellow 83 in Examples 3-4 can be maintained at the highest grade of 5. This shows that the addition of plasticizer in the rubber product is not conducive to the migration resistance of Pigment Yellow 83. The solution in the present invention can reduce the adverse effect of plasticizer on the migration resistance of Pigment Yellow 83 in rubber products with a higher addition of plasticizer. Especially in Examples 3-4, the adverse effect of plasticizer on the migration resistance of Pigment Yellow 83 can be completely overcome.

[0057] Application Example 3 Different from Application Example 1, the usage amount of Pigment Yellow 83 in the rubber product is increased, and each component is weighed according to the following formulation ratio: Nitrile rubber (NBR): 100 parts, Pigment Yellow 83: 30 parts, Plasticizer (DOP): 10 parts, Vulcanizing agent (sulfur): 2 parts, Filler (calcium carbonate): 5 parts.

[0058] The test results of migration resistance are as follows.

[0059] Table 6 Migration resistance of Pigment Yellow 83 in soft rubber products Combining the two groups of data in Example 1, the test data of migration resistance in GB / T 5211.5-2008 (using PVC as the substrate) and the test data of migration resistance in this application example (using nitrile rubber as the substrate), it can be seen by comparison that for the solution in Comparative Example 1, although the migration resistance can reach Grade 4 in the PVC substrate, it can only reach Grade 1 in the nitrile rubber substrate. The migration resistance of Pigment Yellow 83 in Examples 1 and 2 also decreased by one grade in nitrile rubber, while the migration resistance of Pigment Yellow 83 in Examples 3-4 can be maintained at the highest grade of 5. This shows that the addition amount of Pigment Yellow 83 in rubber products also affects the migration resistance of Pigment Yellow 83. The solution in the present invention can reduce the adverse effect of the addition amount of pigment on the migration resistance of Pigment Yellow 83 in rubber products with a relatively high addition amount of pigment. Especially in Examples 3-4, the adverse effect on the migration resistance of Pigment Yellow 83 under the condition of high addition amount can be completely overcome.

Claims

1. A method for preparing Pigment Yellow 83 for rubber products, comprising the following steps: S1. Preparation of diazo liquid: Mix 3,3′-dichlorobenzidine and hydrochloric acid, stir until completely dissolved; cool to T≤3°C, add sodium nitrite solution, carry out diazotization reaction, filter after the reaction, and obtain diazo liquid; S2. Preparation of coupling solution: adding 2,5-dimethoxy-4-chloroacetoacetanilide to a sodium hydroxide solution, stirring until completely dissolved, adding acetic acid solution, stirring thoroughly and adjusting the pH to 6-8 to obtain a coupling solution; S3 coupling reaction: the coupling solution was heated to 15 to 25 ° C, diazo solution was added dropwise, stirred, kept warm, and a coupling reaction was carried out to obtain a reaction solution; S4. Pigment strengthening: adding a mobility enhancing agent to the reaction solution for treatment, filtering, drying and grinding the treated mixture to obtain Pigment Yellow 83; The mobility enhancer is one or a mixture of polycarboxylate, polyether block copolymer or siloxane modified polymer.

2. The preparation method according to claim 1, characterized in that: The added amount of the mobility enhancer is 1.5-5% based on the mass of 3,3'-dichlorobenzidine.

3. The preparation method according to claim 1, characterized in that: The mobility enhancing agent is a polycarboxylate.

4. The preparation method according to claim 1, characterized in that: The 3,3'-dichlorobenzidine is firstly wetted with an alcohol solution before being mixed with hydrochloric acid.

5. The preparation method according to claim 4, characterized in that: The alcohol solution is an ethanol solution.

6. The preparation method according to claim 5, characterized in that: The volume concentration of the ethanol solution is 65 to 80%.

7. The preparation method according to claim 1, characterized in that: Step S4, the strengthening conditions for pigment strengthening are: temperature 40 to 60° C., pressure 0.5 to 1.2 MPa.

8. The preparation method according to claim 1, characterized in that: The Pigment Yellow 83 obtained in step S4 is refined, and the refining steps are as follows: A. Disperse Pigment Yellow 83 in the pigment emulsifier to form a pigment emulsion; B. Control the pigment emulsion to reach the freezing point of the pigment emulsion or below, to obtain a frozen pigment emulsion; C. The frozen pigment emulsion was crushed with an ultrasonic pulverizer, ball-milled, and dried to obtain refined Pigment Yellow 83.

9. The preparation method according to claim 8, characterized in that: In step B, the temperature of the pigment emulsion is controlled to gradually decrease to a temperature at or below the freezing point of the pigment emulsion.

10. A pigment yellow 83, characterized in that: The method is obtained by the preparation method according to any one of claims 1 to 9.

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