CN1800225A - Latex type hydroxy acryl acid resin possessing core-shell configuration - Google Patents

Abstract

The present invention relates to an emulsion-type hydroxyl-containing acrylic resin with a core-shell configuration, which is formed by emulsion polymerization of the following four vinyl monomers in the presence of an initiator and an emulsifier. The types and amounts of the monomers are as follows: ① 60-80% of vinyl monomers without other functional functional groups; 20-40% of vinyl monomers containing hydroxyl groups; 2-8% of vinyl monomers containing epoxy groups; ④carboxyl-containing vinyl monomers 1-5% vinylic monomers; among them, 20-40% of the monomer ① is used as the core monomer, and the remaining monomer ① is mixed with the monomers ②, ③, ④ as the shell-forming monomer to form the core-shell configuration, the above percentages are percentages by weight. The resin can be used as a hydroxyl resin for two-component coatings, with low VOC content and high solid content, and the formed coating film has improved hardness, flexibility and various resistances. For example: coating of wood, plastic, metal, glass and concrete. It can replace traditional solvent-based two-component polyurethane self-drying paint and solvent-based amino baking varnish.

Description

Emulsion-type hydroxyl-containing acrylic resin with core-shell configuration

technical field

The invention relates to an emulsion-type hydroxyl-containing acrylic resin with a core-shell configuration, which is especially suitable for use as a hydroxyl component in two-component water-based wood coatings, water-based anti-corrosion coatings, and the like.

Background technique

With the increasingly stringent environmental protection requirements around the world, water-based coating products have been applied on a large scale. However, due to the restriction of its own preparation mechanism, it is difficult to effectively improve the medium resistance and hardness of the coating film by conventional methods. In this case, people began to study the water-based hydroxyl resin that can be cross-linked by adding a curing agent. Emulsion-type hydroxy-containing acrylic resins have lower cost and higher solid content than those synthesized by solvent method, neutralized salt-forming, water-dispersed hydroxy resins and water-soluble polyurethane hydroxy resins. The key is the content of volatile organic compounds (VOC) few. Now it has been widely concerned by domestic and foreign research institutes and paint manufacturers and has actively participated in research and development. U.S. Patent No. 5,641,829 uses hydroxyethyl acrylate, butyl acrylate and acrylic acid as monomers, polymerizes under a solvent, after the reaction is complete, neutralizes with alkali and disperses with water to form a water-dispersed hydroxy resin, and gets 243.0 parts of it with 39.8 parts of cross-linking agent (trade name Cymel 327), cross-linked and cured in the presence of phosphate catalyst, the formed coating film has good medium resistance. However, since the water-dispersed hydroxyl resin is polymerized by a solvent method, the VOC content is high and the solid content is low. International patent application WO 01-72909 relates to a water-based hydroxyl-containing polymer, which is divided into three stages in the polymerization process: the monomer composition ratio of the first stage is methyl methacrylate/butyl acrylate/methacrylic acid 441.6/147.2 /11.9, the monomer composition ratio of the second stage is methyl methacrylate/butyl acrylate/hydroxyethyl acrylate 71.0/35.0/6.9, the monomer composition ratio of the third stage is methyl methacrylate/butyl acrylate/acrylic acid Hydroxyethyl ester/methacrylic acid 12.3/30.8/40.2/22.7; take 165 parts of the hydroxyl emulsion, 150 parts of aluminum powder slurry and 112 parts of polyurethane dispersion to get good coating performance of aluminum powder paint, but the synthesis process of the emulsion It is complicated, and the various resistances of the obtained coating film are still unsatisfactory. Chinese patent application 200410051550.2 discloses a hydroxyacrylic emulsion with a microgel core structure, which firstly copolymerizes a vinyl silane coupling agent and an acrylate monomer to obtain a core with a microgel structure, and then carries out hydroxyl-containing vinyl on the surface of the core. Copolymerization of base monomers and acrylate monomers, the core can be self-crosslinked, and the hydroxyl groups on the shell are used for external linking, which increases the crosslinking points and improves the hardness and resistance of the coating film, but it will cause the coating film to become brittle. The flexibility becomes poor; all of them are synthesized with conventional emulsifiers, which are easy to foam and affect the water resistance of the coating; the microgel structure will enhance the activity of the system, and the service life of the prepared coating is short, only 3 to 6 hours.

Contents of the invention

The purpose of the present invention is to provide an emulsion-type hydroxyl-containing acrylic resin with a core-shell structure, which has low VOC content and high solid content, and the formed coating film has improved hardness, flexibility and various resistances.

The technical scheme for realizing the purpose of the present invention: a kind of emulsion type hydroxyl-containing acrylic resin with core-shell configuration, which is formed by emulsion polymerization of the following 4 kinds of ethylenic monomers in the presence of initiators and emulsifiers. The percentages of types and amounts of each monomer in the total amount of monomers are as follows: ① 60-80% of vinyl monomers without other functional functional groups; ② 20-40% of vinyl monomers containing hydroxyl groups; ③ 2 to 8% vinyl monomers containing epoxy groups; 1 to 5% vinyl monomers containing carboxyl groups;

The amount of the initiator is 0.2% to 0.7% of the total amount of monomers;

The emulsifier is a reactive emulsifier, or a reactive emulsifier and a conventional small molecule emulsifier, and the weight ratio of the two amounts is 7.5 to 15.0:1; the total amount of the emulsifier is 0.3 to 2.0% of the total amount of monomers ;

During emulsion polymerization, 20-40% of the monomer ① is firstly polymerized into the seed emulsion as the nucleus, and the remaining monomer ① is mixed with the monomer ②, ③, ④ as the shell-forming monomer. The surface aggregates into a shell, forming a core-shell configuration;

The above percentages are percentages by weight.

The monomer ① is: two or more of acrylate or methacrylate monomers and aromatic vinyl monomers. For example, methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, (meth) (meth)acrylate monomers such as cyclohexyl acrylate and lauryl (meth)acrylate; aromatic vinyl monomers such as styrene, methylstyrene, and vinyltoluene.

The above-mentioned emulsion-type hydroxyl-containing acrylic resin, wherein, the percentages of the following monomers in the total amount of monomers are preferably: hydroxyl-containing ethylenic monomers ② 22% to 26%; epoxy-containing ethylenic monomers ③ 3-3% 5%; carboxyl-containing ethylenic monomers ④ 1-2%.

The above-mentioned emulsion-type hydroxyl-containing acrylic resin, wherein, the said hydroxyl-containing ethylenic monomer ② is: one or more kinds of hydroxyl ester monomers of acrylic acid or methacrylic acid. For example, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, and the like.

The above-mentioned emulsion-type hydroxyl-containing acrylic resin, wherein, the epoxy-containing ethylenic monomer ③ is one or more than one of glycidyl ester monomers of acrylic acid or methacrylic acid. For example, glycidyl (meth)acrylate, allyl glycidyl, and the like.

The above-mentioned emulsion-type hydroxyl-containing acrylic resin, wherein, the carboxyl-containing ethylenic monomer ④ is: one or one of acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, and fumaric acid above.

The above-mentioned emulsion type hydroxyl-containing acrylic resin, wherein, the reactive emulsifier is one or more of anionic or nonionic reactive emulsifying monomers, such as: sodium methacrylamide isopropyl sulfonate, SE-10N, NE-10, etc., the conventional small molecule emulsifiers, such as: sodium lauryl sulfate, sodium dodecylbenzenesulfonate, etc.

The above-mentioned emulsion-type hydroxyl-containing acrylic resin, wherein, the initiator is a persulfate, such as: ammonium persulfate, potassium persulfate and the like.

The above-mentioned emulsion type hydroxyl-containing acrylic resin has the appearance of a milky white slightly transparent blue light liquid, a viscosity of 200-2000Mpa·s, a solid content of 42-46%, a pH value of 7.0-8.5, a particle size of 0.05-0.2μm, and a volatile organic compound VOC The content is less than 0.1%, the hydroxyl content is 2.5-3.5%, and the storage period is more than 6 months.

The emulsion-type hydroxyl-containing acrylic resin of the present invention can be produced with existing emulsion polymerization equipment.

When preparing the resin of the present invention, first heat in the presence of an emulsifier and an initiator to polymerize 20 to 40% of the monomer ① to form a nuclear emulsion, and then add the emulsifier, the initiator and the remaining monomers dropwise at the same temperature ①The mixture with monomer ②, monomer ③, and monomer ④ makes them polymerize on the particle surface to form a shell containing hydroxyl, epoxy and carboxyl groups. After neutralization, the carboxyl groups form salts, and the functional groups are retained in the shell ( hydroxyl group and epoxy group), and finally formed the emulsion type hydroxyl-containing acrylic resin with core-shell configuration of the present invention.

Technical effects of the present invention: the emulsion type hydroxyl-containing acrylic resin with core-shell configuration of the technical solution of the present invention has the following beneficial effects: one is because the resin of the present invention is an emulsion type, when formula design, water is used as the dispersion medium, No organic solvent is added, so it is safe, non-toxic and environmentally friendly (VOC content is less than 0.1%), In addition, since the water-dispersed hydroxyacrylic resin formed by solvent polymerization has the problem of dilution peak, the solid content is lower than 40%, while the solid content of the resin of the present invention can reach 46%, which can indirectly improve the construction efficiency. The second is to use reactive emulsifying monomer or reactive emulsifying monomer plus a very small amount of conventional small molecule emulsifier as the emulsifier of the system. The advantage is that the emulsion has low foam, and the water resistance and transparency of the coating film are improved. The third is that the resin of the present invention has a standard core-shell configuration, and due to formula design, it has been determined to use vinyl monomers containing appropriate functional functional groups as nucleating monomers; the amount of each monomer has been determined ; From the ethylenic monomers that do not contain other functional functional groups, determine the appropriate amount as the core monomer; during implementation, after the polymerization nucleation, the remaining ethylenic monomers that do not contain functional functional groups, It is then added together with hydroxyl-containing vinyl monomers, carboxyl-containing vinyl monomers, and epoxy-containing vinyl monomers. Therefore, after emulsion polymerization forms a shell, there will be an appropriate amount of functional functional groups (hydroxyl groups) and epoxy) can be distributed on the surface of latex particles. When the resin of the present invention is used as the hydroxyl component of the two-component coating, the hydroxyl group of the shell layer can fully participate in the reaction, improve the crosslinking efficiency of the formed coating film, thereby improving the hardness and various resistances of the coating film, as the polymerization of the core The compound does not participate in the crosslinking reaction during film formation, which endows the coating film with good flexibility; at the same time, the polymer as the core has low activity, so that the prepared coating has a long service life (> 24 hours). The fourth is that the epoxy group introduced in the shell layer further increases the hardness of the coating film and the resistance to various media of the coating film.

Detailed ways

The present invention will be further described in detail below in conjunction with the examples, but not limited thereto.

The parts in the embodiment and the comparative example formula are all parts by weight; Unless otherwise specified, all raw materials are commercially available industrial products of coating grade; ~7.5, conductivity≤0.50mS/m).

Embodiment 1～3:

The recipe is shown in Table 1

Table 1 Material number raw material name Embodiment 1 (part) Example 2 (parts) Embodiment 3 (parts) 1 (medium) Deionized water 160.0 160.0 140.0 2 (emulsifier and initiator) Deionized water 20.0 20.0 20.0 SE-10N / 0.6 0.3 NE-10 / / 0.3 AMPS (active ingredient 50%) 1.2 / / Sodium dodecyl sulfate 0.2 / / Ammonium persulfate 0.3 0.3 0.3 3 (nucleating monomer ①) Methyl methacrylate 20.0 10.0 2.0 Butyl acrylate 15.0 20.0 15.0 Styrene / / 12.0 4 (emulsifier and initiator) Deionized water 30.0 30.0 30.0 SE-10N / 1.2 1.0 NE-10 / / 1.0 AMPS (active ingredient 50%) 2.8 / / Ammonium persulfate 0.5 0.5 0.5 5 (shell-forming monomer) Monomer ① Methyl methacrylate 45.0 30.0 5.0 Butyl acrylate 35.0 50.0 40.0 Styrene / / 35.0 Monomer② Hydroxypropyl Acrylate 30.0 / / Hydroxyethyl methacrylate / 35.0 40.0 Monomer③ Glycidyl methacrylate 3.0 6.0 4.0 Monomer ④ acrylic acid 3.2 / / Methacrylate / 2.2 1.6 6 (mixture) ammonia 2.6 1.6 1.0

Note:

Embodiment 1: monomer 1. accounts for 76.06%; monomer 2. accounts for 19.84%; monomer 3. accounts for 1.98%; monomer 4. accounts for 2.12%; emulsifier accounts for 1.46% of monomer total amount; 0.53% of;

Embodiment 2: monomer 1. accounts for 71.80%; monomer 2. accounts for 22.84%; monomer 3. accounts for 3.92%; monomer 4. accounts for 1.44%; emulsifier accounts for 1.17% of monomer total amount; 0.52% of;

Embodiment 3: monomer 1. accounts for 70.51%; monomer 2. accounts for 25.87%; monomer 3. accounts for 2.59%; monomer 4. accounts for 1.03%; emulsifier accounts for 1.68% of monomer total amount; 0.52% of;

AMPS in the table is an anionic reactive emulsifying monomer of Lubrizol Corporation of the United States:

Molecular formula: CH ₂ ＝CH-CO-NH-C(CH ₃ ) ₂ -CH ₂ -SO ₃ Na, (sodium methacrylamide isopropyl sulfonate) 50% active ingredient;

SE-10N in the table is an anionic reactive emulsifying monomer of Japan Asahi Denka Corporation:

100％有效成份；Molecular formula:

100% active ingredients;

NE-10 in the table is the non-ionic reactive emulsifying monomer of Japan Asahi Denka Co., Ltd.

100％有效成份。Molecular formula:

100% Active Ingredients.

Synthesis:

In a 500ml three-necked bottle equipped with a heating device, a stirring device, a thermometer and a condensing device, add material 1 according to the formula in Table 1, raise the temperature to 80°C and add material 2, then add material 3 dropwise within 1 hour, and keep warm after dropping After 0.5 hour, a seed nucleus emulsion is generated. Then at the above temperature, the material 4 and the material 5 were added dropwise at the same time, and the drop was completed within 3 hours. Keep warm for 2 hours after dripping. Then lower the temperature to 50°C, add material 6 to neutralize, stir evenly, and filter out the material to obtain the resins of the present invention in Examples 1-3 respectively, and their technical specifications are shown in Table 2.

comparative example

The comparative example is a hydroxyl-containing acrylic resin prepared by a conventional emulsion polymerization process using a conventional small-molecule emulsifier, and no ethylenic monomers with epoxy groups are added to the formula.

Formula: ① 160.0 parts of deionized water, ② 50.0 parts of deionized water, 1.6 parts of sodium lauryl sulfate and 0.6 parts of ammonium persulfate, ③ 65.0 parts of methyl methacrylate, 55.0 parts of butyl acrylate, hydroxypropyl acrylate 30 parts and 2.7 parts of acrylic acid, ④ 2.0 parts of ammonia water;

In a 500ml three-necked bottle equipped with a heating device, a stirring device, a thermometer and a condensing device, add material ①, raise the temperature to 80°C and add material ② and material ③ dropwise, and the drop is completed within 3 hours. Keep warm for 2 hours after dripping. Then lower the temperature to 50°C, add the material ④ to neutralize, stir evenly, and filter out the material to prepare the hydroxyl-containing acrylic resin of the comparative example. The technical specifications are shown in Table 2.

Table 2 index Example 1 Example 2 Example 3 comparative example Exterior Milky white slightly transparent blue light Milky blue light intensity Milky blue light intensity Milky blue light intensity Coagulation rate, % <0.2 <0.1 <0.2 <0.2 Viscosity, Mpa·s 300 360 1200 680 Solid content, % 42.1 42.5 44.2 42.2 Hydroxyl content, % 2.6 3.0 3.4 2.6 pH value 8.3 7.8 8.0 8.2 Average particle size, μm 0.15 0.08 0.10 0.10 VOC content, % <0.1 <0.1 <0.1 <0.1 Shelf life, months >6 >6 >6 >6

Coating film performance test after film formation

100g above-mentioned resin is made into two-component polyurethane coating (the coating service life of embodiment 1～3 is at least 24 hours) as hydroxyl component and 10g polyisocyanate component B 2336 (BAYER company, NCO content is 18%), coating Covered on a tin plate with a thickness of 20 μm (dry film), after drying for 10 days at 25°C and a humidity of 50%, the performance of the coating film was tested, and the results are shown in Table 3.

table 3 Test items Example 1 Example 2 Example 3 comparative example Detection method Exterior Transparent and flat Transparent and flat Transparent and flat Transparent and flat visual inspection Adhesion, grade 0～1 0～1 0～1 0～1 GB/T9286-1998 Flexibility, mm 1 1 1 2 GB/T1731-93 pencil hardness 2H h 2H h GB/T6739-1996 Water resistance, 72h no change no change no change whitening Note 1 Acetone extraction rate, % <10 <10 <10 >30 Note 2

Note 1: Water resistance test method

Coat different emulsion polymers on glass plates of 8cm×12cm to make coating films with a thickness of about 20μm. After drying at 25°C for 7 days, soak them in deionized water to observe the whitening, foaming and Shedding situation.

Note 2: Detection method of acetone extraction rate

After the emulsion is formed into a film and solidified on a glass plate with a weight of m ₀ , weigh it (m ₁ ), then immerse it in a large amount of acetone solution and leave it for 7 days, take it out and dry it, weigh it (m ₂ ), and calculate the acetone extraction rate according to the following formula (f).

$\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; =</span>\frac{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>}{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; 100</span>}<span\; class="notranslate">\; \%</span>$

Due to the use of reactive emulsifying monomers, the water resistance of the coating film is improved, the core-shell configuration of the latex particles, the shell hydroxyl and epoxy functional groups fully participate in the cross-linking reaction, and the cross-linking of the coating film is improved. Degree and hardness, inner core layer polymer does not participate in cross-linking reaction, endows good flexibility of coating film, so compared with comparative example, the cross-linking degree, flexibility and water resistance of the coating film that resin of the present invention forms have obvious improvement improve. The emulsion-type hydroxyl-containing acrylic resin of the present invention can be used as the hydroxyl component to prepare various two-package two-component coatings, which can be baked and cured at 120-180 ° C, and can also be cured at room temperature. It is widely used in various substrates, such as: wood , plastic, metal, glass and concrete surface coating. It can replace traditional solvent-based two-component polyurethane self-drying paint and solvent-based amino baking varnish.

Claims (7)

1, a kind of latex type hydroxy acryl acid resin with core-shell configuration, it is characterized in that: it is that following 4 kinds of vinyl monomers are in the presence of initiator and emulsifying agent, letex polymerization forms, and monomeric species and each monomer consumption shared per-cent in the monomer total amount are as follows: the vinyl monomer 60～80% that does not 1. contain other functional functional group; 2. the vinyl monomer 20～40% of hydroxyl; 3. the vinyl monomer 2～8% that contains epoxy group(ing); 4. carboxylic vinyl monomer 1～5%;

Described initiator amount is 0.2～0.7% of a monomer total amount;

Described emulsifying agent is a reactive emulsifier, or reactive emulsifier and conventional small-molecular emulsifier, and the weight ratio of the two consumption is 7.5～15.0: 1; The total consumption of emulsifying agent is 0.3～2.0% of a monomer total amount;

During letex polymerization, 1. 20～40% monomer at first aggregates into the seed emulsion as nuclear, and 2., 3., 4. 1. residual monomers mix as becoming shell monomer with monomer again, becomes shell, the formation core-shell configuration at the surface aggregate of established nuclear particle;

1. described monomer is two or more in esters of acrylic acid or methyl acrylic ester monomer, the aromatic series vinyl monomer;

Above per-cent all is weight percentage.

2, latex type hydroxy acryl acid resin according to claim 1 is characterized in that: following monomer consumption shared per-cent in the monomer total amount is preferably: the vinyl monomer of hydroxyl 2. 22～26%; The vinyl monomer that contains epoxy group(ing) 3. 3～5%; Carboxylic vinyl monomer 4. 1～2%.

3, latex type hydroxy acryl acid resin according to claim 1 and 2 is characterized in that: 2. the vinyl monomer of described hydroxyl is one or more in the hydroxyl esters monomer of acrylic acid or methacrylic acid.

4, latex type hydroxy acryl acid resin according to claim 1 and 2 is characterized in that: one or more in the Racemic glycidol esters monomer that 3. the described vinyl monomer that contains epoxy group(ing) is acrylic acid or methacrylic acid.

5, latex type hydroxy acryl acid resin according to claim 1 and 2 is characterized in that: 4. described carboxylic vinyl monomer is one or more in vinylformic acid, methacrylic acid, butenoic acid, methylene-succinic acid, toxilic acid, the fumaric acid.

6, latex type hydroxy acryl acid resin according to claim 1 and 2 is characterized in that: described reactive emulsifier is one or more in the reactive emulsified monomer of anionic or non-ionic type.

7, the latex type hydroxy acryl acid resin of stating according to claim 1 or 2, it is characterized in that: its outward appearance is the little blue light liquid of oyster white, viscosity 200～2000Mpas, solids content 42～46%, pH value 7.0～8.5, particle diameter 0.05～0.2 μ m, volatile organic compounds VOC content＜0.1%, hydroxy radical content 2.5～3.5%, storage period is more than 6 months.