A non-fading stabilizer and a method for preparing the same

Abstract

The application discloses a novel colorless stabilizer and a preparation method thereof, and particularly relates to the field of emulsion polymerization auxiliary agent preparation. The colorless stabilizer comprises 0.5-5% of a stabilizer, 0.5-5% of a synergist, 5-15% of an organic amine neutralization catalyst, 1-6% of a complexing agent, 25-40% of an organic solvent, 1-6% of an emulsifier, and the rest is distilled water. The novel colorless stabilizer can replace traditional ethylenediamine and other organic amines to improve the anti-blocking property, durability and adhesion of acetylacetoxy-containing acrylate emulsion. The novel colorless stabilizer can improve the hand feeling, elasticity and flexibility of the coating film or printed product, and improve the corrosion resistance and hydrolysis resistance. The novel colorless stabilizer has high quality, low production cost and simple use, and can well meet the needs of domestic textile auxiliaries, coating chemical and other acrylate emulsion production manufacturers.

Description

Technical Field

[0001] This invention relates to the field of emulsion polymerization aids preparation, specifically to a non-color stabilizer and its preparation method, and more specifically to a non-color stabilizer that can prevent yellowing and discoloration of coatings or printed patterns of acrylate emulsions containing acetyl acetoxy groups, and can replace commonly used organic amines such as ethylenediamine to improve their anti-blocking properties, durability and adhesion. Background Technology

[0002] Aqueous dispersions (also known as aqueous adhesives) are becoming increasingly important than solvent-based adhesives due to their fewer environmental concerns. Among the commonly used crosslinking monomers in aqueous dispersions, olefinically unsaturated acetoacetoxy functional monomers include acetoacetoxyethyl methacrylate (“AAEM”), acetoacetoxyethyl acrylate, acetoacetoxypropyl methacrylate, allyl acetoacetate, vinyl acetoacetate, acetoacetoxybutyl methacrylate, 2,3-di(acetoacetoxy)propyl methacrylate, and tert-butyl acetoacetate. These monomers are preferred for synthesizing high-solids-content liquid acrylic resins and low-VOC acrylic emulsions for industrial and architectural coatings due to their advantages such as being environmentally friendly and formaldehyde-free, forming films at low temperatures without relying on film-forming aids, exhibiting excellent elasticity and flexibility, and possessing good corrosion and hydrolysis resistance. Furthermore, their low cost and ease of synthesis make them ideal for synthesizing high-solids-content liquid acrylic resins and low-VOC acrylic emulsions for industrial and architectural coatings.

[0003] However, coatings or printed patterns using acrylic polymers containing acetylacetoxy crosslinking monomers often exhibit yellowing and discoloration when exposed to sunlight, especially as the film ages over time. In some cases of improper polymerization processes, this problem can even occur during the product drying stage. This is because the conjugation effect of the dicarbonyl group on the acetylacetoxy group results in an extremely reactive -H group on the methylene group, exhibiting strong reducing properties. It is easily oxidized and delocalized, forming a free radical-like structure. This structure can undergo addition with its isomer—the enol double bond—or self-polymerize, thus serving as a crosslinking monomer to achieve molecular chain crosslinking at room temperature. Simultaneously, this structure readily forms a hydrogen-bonded lactone macrocyclic structure in aqueous solution under the influence of water, a polar solvent, causing discoloration of the emulsion and coating. To avoid emulsion discoloration, the polymerization reaction temperature should be controlled below 83°C when using acetylacetoxy crosslinking monomers. If the amount of crosslinking monomer reaches or exceeds 4% of the total monomer amount, a low-temperature redox reaction catalyzed by ferrous sulfate heptahydrate must be employed. After polymerization, ammonia is typically added to neutralize the acrylate emulsion to approximately pH 8.0-10.0 to prevent the hydrolysis of acetoacetyl groups during storage. To ensure desired properties such as anti-blocking, durability, and adhesion, organic amines such as ethylenediamine and hexamethylenediamine, which can form stable and secondary crosslinking enamine structures with acetoacetyl groups in the aqueous phase, are often added. The iron ions and primary amines introduced during this process are unstable factors that can cause yellowing and discoloration of the emulsion coating and printed products if the usage and dosage are not carefully controlled. Even with these measures, the hydrolysis and discoloration of acetoacetyl groups cannot be completely avoided as ammonia evaporates and the emulsion pH changes.

[0004] Reducing yellowing and discoloration of emulsion coatings is a common challenge in the acrylic emulsion industry. US Patent No. 7,417,086 discloses a method for preparing acrylic emulsions that provide coatings with less yellowing. In some embodiments, to reduce yellowing, methods are employed that completely or substantially eliminate ammonia compounds and ammonium salts in all aspects, including emulsifiers, initiators, neutralizers, and buffers. Other companies, both domestically and internationally, generally adopt similar approaches, making specific adjustments or improvements for their own products. For example, US Patent No. 10,982,030 reduces yellowing of its acetyl acetoxy-based aqueous emulsion polymer by incorporating 0.3% to 10% of an olefinically unsaturated monomer with at least one functional group selected from sulfonate, phosphate, hydroxyl, amide, or urea groups, and 0 to 1% of an olefinically unsaturated acid monomer. Currently, there is no universally applicable solution for the yellowing and discoloration problem of acrylic emulsion coatings or printed patterns containing acetyl acetoxy groups.

[0005] Therefore, developing a class of non-color stabilizers that can prevent yellowing and discoloration of coatings or printed patterns of acrylic emulsions containing acetyl acetoxy groups, and that can replace commonly used organic amines such as ethylenediamine to improve their anti-blocking properties, durability, and adhesion, is of great significance in solving the difficult problems encountered in the production of acrylic emulsions. Summary of the Invention

[0006] Therefore, this invention provides a non-coloring stabilizer and its preparation method to solve the problem of yellowing and discoloration of coatings or printed patterns containing acetyl acetoxy groups during drying or storage, especially when exposed to sunlight and aging over time. This product is added after the acrylate emulsion polymerization is completed, cooled, and neutralized with ammonia to pH=7. It effectively prevents yellowing caused by the hydrolysis of acetyl acetoxy groups and other factors, while improving its required anti-blocking, durability, and adhesion properties.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] According to one aspect of the present invention, a non-coloring stabilizer is provided, the stabilizer comprising 0.5-5% stabilizer, 0.5-5% synergist, 5-15% organic amine neutralizing catalyst, 1-6% coordination agent, 25-40% organic solvent, 1-6% emulsifier, and the remainder being distilled water.

[0009] Furthermore, the stabilizer is 2,2'-methylene-bis-(4-methyl-6-tert-butylphenol) and / or 2,6-di-tert-butyl-4-methylphenol. As an example, a dosage of 2-3% is preferred.

[0010] Furthermore, the synergist is tris-(4-nonyl-phenyl)-phosphite and / or bis[2-methyl-4,6-bis(1,1'-dimethylethyl)phenol] ethyl phosphate. As an example, a dosage of 2-3% is preferred.

[0011] The weight ratio of the stabilizer and synergist combination is 4:1 to 1:4, and as an example, 2:1 to 1:2 is preferred.

[0012] Furthermore, the organic amine neutralization catalyst is triethylenediamine or triethylamine. As an example, a preferred dosage is 10-12%.

[0013] Furthermore, the ligand is one or more of sodium pyrophosphate, sodium tripolyphosphate, sodium hexametaphosphate, sodium phosphonoacetate, sodium 2-hydroxy-2-phosphonoacetate, and disodium ethylenediaminetetraacetate. As an example, a preferred dosage is 3-4%.

[0014] Furthermore, the organic solvent is dipropylene glycol, propylene glycol, ethylene glycol, or diethylene glycol. As an example, a preferred amount is 30-40%.

[0015] Furthermore, the emulsifier is a silicone-modified polyether phosphate. As an example, a preferred dosage is 2-4%.

[0016] A method for preparing a non-coloring stabilizer according to another aspect of the present invention includes:

[0017] Step 1: Add the stabilizer, synergist, organic amine neutralizing catalyst and organic solvent into a feeding tank equipped with stirring and heating functions, and heat and stir until completely dissolved;

[0018] Step 2: Add the complexing agent, emulsifier, and distilled water into the emulsification mixing tank, and heat and stir until completely dissolved;

[0019] Step 3: Under high-speed stirring, slowly add the product from Step 1 to the solution obtained in Step 2;

[0020] Step 4: After adding the materials, continue stirring at a constant temperature for 30 minutes, then cool and discharge to obtain the color-reducing stabilizer.

[0021] Furthermore, in steps one, two, and four, the heating and constant temperature is 40-60℃.

[0022] Furthermore, in steps one and two, the stirring speed is 160-200 r / min.

[0023] Furthermore, in steps three and four, the stirring speed is 1000-1200 r / min.

[0024] The present invention has the following advantages:

[0025] 1. The color-reducing stabilizer of the present invention can solve the problem of yellowing and discoloration of coatings or printed patterns containing acetyl acetoxy groups during drying or storage, especially when exposed to sunlight and aging over time. Adding the stabilizer after the acrylate emulsion polymerization is complete, cooling, and neutralization with ammonia to pH=7 effectively prevents yellowing caused by the hydrolysis of acetyl acetoxy groups and other factors.

[0026] 2. The color-reducing stabilizer of this invention can replace traditional organic amines such as ethylenediamine to improve the anti-blocking, durability, and adhesion properties of acrylate emulsions containing acetyl acetoxy groups. It also improves the hand feel, elasticity, flexibility, corrosion resistance, and hydrolysis resistance of coated or printed products.

[0027] 3. The color-reducing stabilizer of the present invention is of high quality, low production cost, and easy to use, which can well meet the needs of domestic manufacturers of acrylic emulsions such as textile auxiliaries and coating chemicals. Detailed Implementation

[0028] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] Example 1

[0030] This embodiment provides a non-coloring stabilizer, and the weight ratio of each component is shown in Table 1.

[0031] Table 1

[0032]

[0033] Example 2

[0034] This embodiment provides a non-coloring stabilizer, and the weight ratio of each component is shown in Table 2.

[0035] Table 2

[0036]

[0037] Example 3

[0038] This embodiment provides a non-coloring stabilizer, and the weight ratio of each component is shown in Table 3.

[0039] Table 3

[0040]

[0041] Example 4

[0042] This embodiment provides a method for preparing the non-color-changing stabilizers of Examples 1-3:

[0043] Step 1: Add the stabilizer, synergist, organic amine neutralizing catalyst and organic solvent into a feeding tank equipped with stirring and heating functions, and heat and stir until completely dissolved;

[0044] Step 2: Add the complexing agent, emulsifier, and distilled water into the emulsification mixing tank, and heat and stir until completely dissolved;

[0045] Step 3: While stirring at high speed, slowly add the product from step 1 to the solution obtained from step 2.

[0046] Step 4: After adding the materials, continue stirring at a constant temperature for 30 minutes, then cool and discharge to obtain the color-reducing stabilizer.

[0047] The feeding tank and emulsifying stirring vessel mentioned in steps one and two are both parts of a stainless steel reactor and are heated by steam.

[0048] The heating and constant temperature described in further steps one, two and four is 40-60℃.

[0049] In further steps one and two, the stirring speed is 160-200 r / min.

[0050] In further steps three and four, the stirring speed is 1000-1200 r / min.

[0051] Experimental Example

[0052] The color-reducing stabilizer products 1-3 prepared according to the components of Examples 1-3 of this invention, along with the blank sample, ethylenediamine, and BY-9550 from Beijing Baiyuan Chemical Co., Ltd., were all added to the same acrylate emulsion containing acetylacetoxy groups. After being left overnight, the following comparative tests were conducted.

[0053] The dosage of finished products 1-3 and BY-9550 is equivalent to the mass of AAEM converted from the acetyl acetoxy content. The dosage of ethylenediamine is 1 / 4 of the mass of AAEM, but it needs to be prepared as a 20% aqueous solution before being added.

[0054] 1. Film-forming softness and feel

[0055] Spread the emulsion in a clean, dry petri dish, dry it, and then bake it at 140°C for 3 minutes. Check the dryness and softness by hand.

[0056] 2. Film strength and toughness

[0057] The baked film was cut into dumbbell-shaped strips with a middle width of 6mm. The stress and strain were measured on an AI-7000-SU1 tensile testing machine at room temperature and a tensile speed of 200mm / min to obtain the tensile strength and elongation at break.

[0058] 3. The coating is resistant to hydrostatic pressure.

[0059] A 190T polyester taffeta sample was stretched taut on a frame. The emulsion was evenly applied to the sample with a scraper, using only one scrape. The scraper angle was controlled to keep the fabric coating weight at approximately 8 g / cm². The sample was then baked at 140℃ for 3 minutes. Finally, the hydrostatic pressure resistance of the coated fabric was determined using a YG812N fabric water permeability tester according to GB / T 4744-2013.

[0060] 4. Yellowness

[0061] The test emulsion was spread evenly on a clean and dry glass plate using a 100μm applicator. Three sets of samples were prepared for each sample. Sample 1 was air-dried at room temperature in the absence of oxygen to serve as the template; Sample 2 was baked at 130℃ for 2 minutes; Sample 3 was baked at 130℃ for 2 minutes and then placed in an oven at 50℃ for two weeks. The Δb value Δb1 of Sample 2 and the Δb value Δb2 of Sample 3 were measured using a colorimeter. The lower the Δb value, the less yellowing.

[0062] The results are shown in Table 4.

[0063] Table 4 Comparison of test results

[0064]

[0065] As shown in Table 4, the color-reducing stabilizer prepared in this invention can solve the problem of yellowing and discoloration of coatings or printed patterns containing acetyl acetoxy groups during drying or storage, and its effect is better than that of BY-9550. Furthermore, it improves the hand feel, elasticity, flexibility, adhesion, and hydrolysis resistance of acrylic emulsion coatings or printed products without causing severe yellowing like ethylenediamine.

[0066] Therefore, the non-color stabilizer prepared in this invention can improve the anti-blocking, durability and adhesion properties of acrylate emulsions containing acetyl acetoxy groups. It can also improve the hand feel, elasticity and flexibility of the coating or printed products, as well as their corrosion resistance and hydrolysis resistance. It can also prevent the coating or printed pattern from yellowing and discoloring during drying or storage. It is inexpensive, easy to use and has broad application prospects in domestic and international markets.

[0067] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. The application of a color-reducing stabilizer in acrylic emulsion coatings or printed products containing acetyl acetoxy groups, characterized in that, The color-reducing stabilizer includes: Stabilizer 0.5-5%, synergist 0.5-5%, organic amine neutralizing catalyst 5-15%, complexing agent 1-6%, organic solvent 25-40%, emulsifier 1-6%, the remainder is distilled water; The stabilizer is 2,2'-methylene-bis-(4-methyl-6-tert-butylphenol) and / or 2,6-di-tert-butyl-4-methylphenol; The synergist is tris-(4-nonyl-phenyl)-phosphite and / or bis[2-methyl-4,6-di(1,1'-dimethylethyl)phenol] ethyl phosphate; The organic amine neutralization catalyst is triethylenediamine or triethylamine; The ligand is one or more of sodium pyrophosphate, sodium tripolyphosphate, sodium hexametaphosphate, sodium phosphonoacetate, sodium 2-hydroxyphosphonoacetate, and disodium ethylenediaminetetraacetate. The emulsifier is an organosilicon-modified polyether phosphate ester; The organic solvent is dipropylene glycol, propylene glycol, ethylene glycol, or diethylene glycol; The method for preparing the non-color stabilizer includes: Step 1: Add the stabilizer, synergist, organic amine neutralizing catalyst and organic solvent into a feeding tank equipped with stirring and heating functions, and heat and stir until completely dissolved; Step 2: Add the complexing agent, emulsifier, and distilled water into the emulsification mixing tank, and heat and stir until completely dissolved; Step 3: Under high-speed stirring, slowly add the product from Step 1 to the solution obtained in Step 2; Step 4: After adding the materials, continue stirring at a constant temperature for 30 minutes, then cool and discharge to obtain the color-reducing stabilizer.

2. The application according to claim 1, characterized in that, In steps one and two, the stirring speed is 160-200 r / min.

3. The application according to claim 1, characterized in that, In steps three and four, the stirring speed is 1000-1200 r / min.

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