CN111072861B - Hydroxy acrylic emulsion, preparation method thereof and coating - Google Patents

Hydroxy acrylic emulsion, preparation method thereof and coating Download PDF

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CN111072861B
CN111072861B CN201911327471.2A CN201911327471A CN111072861B CN 111072861 B CN111072861 B CN 111072861B CN 201911327471 A CN201911327471 A CN 201911327471A CN 111072861 B CN111072861 B CN 111072861B
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emulsion
composition
vinyl monomer
acrylic emulsion
hydroxyl
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CN111072861A (en
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曾一成
陈寿生
郭玉
朱强
刘志刚
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Shanghai Zhanchen Paint Co ltd
Zhuhai Zhanchen New Material Co ltd
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Shanghai Zhanchen Paint Co ltd
Zhuhai Zhanchen New Material Co ltd
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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F265/00—Macromolecular compounds obtained by polymerising monomers on to polymers of unsaturated monocarboxylic acids or derivatives thereof as defined in group C08F20/00
    • C08F265/04—Macromolecular compounds obtained by polymerising monomers on to polymers of unsaturated monocarboxylic acids or derivatives thereof as defined in group C08F20/00 on to polymers of esters
    • C08F265/06—Polymerisation of acrylate or methacrylate esters on to polymers thereof
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G18/00—Polymeric products of isocyanates or isothiocyanates
    • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
    • C08G18/08—Processes
    • C08G18/16—Catalysts
    • C08G18/22—Catalysts containing metal compounds
    • C08G18/222—Catalysts containing metal compounds metal compounds not provided for in groups C08G18/225 - C08G18/26
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D175/00—Coating compositions based on polyureas or polyurethanes; Coating compositions based on derivatives of such polymers
    • C09D175/04—Polyurethanes
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
    • C09D7/40—Additives
    • C09D7/60—Additives non-macromolecular
    • C09D7/63—Additives non-macromolecular organic
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K2201/00—Specific properties of additives
    • C08K2201/014—Additives containing two or more different additives of the same subgroup in C08K

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Wood Science & Technology (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Paints Or Removers (AREA)
  • Polyurethanes Or Polyureas (AREA)

Abstract

The invention belongs to the technical field of coatings, and particularly relates to a hydroxyl acrylic emulsion, a preparation method thereof and a coating. The preparation method provided by the invention comprises the following steps: providing a first composition and a metal precursor, the first composition comprising: a first vinyl monomer containing carboxyl, wherein the metal precursor is an alkaline compound; reacting the first composition with a metal precursor to prepare a seed emulsion containing metal ions; providing a second composition, and reacting the seed emulsion with the second composition to prepare a core polymer emulsion; providing a third composition, and reacting the core polymer emulsion with the third composition to form a shell layer on the core of the core polymer emulsion to prepare the core-shell type hydroxy acrylic emulsion. Solves the problem of slow drying speed of the hydroxyl acrylic emulsion prepared by the prior art.

Description

Hydroxy acrylic emulsion, preparation method thereof and coating
Technical Field
The invention belongs to the technical field of coatings, and particularly relates to a hydroxyl acrylic emulsion, a preparation method thereof and a coating.
Background
In recent years, with the promotion of environmental regulations in various regions and the transformation of consumer concept, the environmental-friendly water-based wood coating is developed rapidly. Since the performances in the aspects of hardness, solvent resistance, fullness, weather resistance, adhesion and the like can be compared favorably with those of oily coatings, the aqueous two-component polyurethane coating has attracted extensive attention and research in recent years. The raw material composition of the water-based hydroxyl acrylic emulsion has the characteristics of easy adjustment, moderate price, simple and controllable production, good liquid resistance, good light and color retention, good weather resistance and the like, so that the two-component water-based polyurethane coating prepared by using the water-based hydroxyl acrylic emulsion as a main agent for preparing a main film forming substance and matching with a water-based polyisocyanate curing agent is the mainstream choice of the middle-high grade water-based wood coating at present.
In order to improve the production speed of wooden ware products such as furniture and the like, the requirement on the actual drying speed of the aqueous two-component polyurethane wooden ware coating is higher. This requires that the main resin have good drying properties, and that the reaction speed and selectivity between the hydroxyl group (-OH) of the hydroxyacrylic resin and the isocyanate group (-NCO) of the polyisocyanate curing agent be increased. In some technologies, hydroxyl-containing aldehyde ketone resin with low molecular weight is introduced in the preparation process of the hydroxyl acrylic emulsion, so that the emulsion polymerization process is more stable, the hydroxyl content is more controllable, the hardness of a paint film is high, and the paint film has good water resistance, alcohol resistance and heat resistance dryness.
Disclosure of Invention
The invention mainly aims to provide a preparation method of a hydroxyl acrylic emulsion, and aims to solve the problem that the actual drying speed of the hydroxyl acrylic emulsion prepared by the existing process is low.
The invention also aims to provide a hydroxy acrylic emulsion and a paint.
In order to achieve the purpose, the invention adopts the following technical scheme:
a preparation method of a hydroxyl acrylic emulsion comprises the following steps:
providing a first composition and a metal precursor, the first composition comprising: a first vinyl monomer containing carboxyl, wherein the metal precursor is an alkaline compound; reacting the first composition and the metal precursor to prepare a seed emulsion containing metal ions;
providing a second composition, and reacting the seed emulsion and the second composition to prepare a core polymer emulsion;
providing a third composition, and reacting the core polymer emulsion and the third composition to form a shell layer on the core of the core polymer emulsion so as to prepare the core-shell type hydroxy acrylic emulsion.
The preparation method of the hydroxy acrylic emulsion provided by the invention comprises the steps of reacting a first composition for preparing the seed emulsion with a metal precursor, wherein the first composition comprises a first alkene monomer containing carboxyl, the metal precursor can decompose metal ions under an acidic environment, and meanwhile, the metal ions can generate a chelating effect with the carboxyl in a system so as to chelate polymer molecules in the seed emulsion synthesized by the reaction; then, the seed emulsion is reacted with the second composition to obtain a core polymer emulsion in which metal ions are chelated, and then the core polymer emulsion is reacted with a third composition for preparing a shell layer. The method is simple and convenient, easy to operate, free of special reagents, environment-friendly and suitable for large-scale preparation of the hydroxyl acrylic emulsion. The method of the invention prepares the hydroxy acrylic emulsion with the metal ions chelated in the core by introducing the metal ions into the seed emulsion, and in the film forming process, after the hydroxy acrylic emulsion particles are fully fused with the polyisocyanate curing agent, the chelated parts of the metal ions and the polymer molecular chains can be used as catalysts to accelerate the reaction between isocyanate groups and hydroxyl groups, thus greatly improving the actual drying speed and the crosslinking density of the paint film. Thus, the polyurethane coating prepared from the hydroxyacrylic emulsion has excellent drying speed, proper pot life, excellent liquid resistance and good mechanical properties.
Correspondingly, the hydroxyl acrylic emulsion is prepared by the preparation method.
The hydroxyl acrylic emulsion provided by the invention is prepared by the preparation method, has a core-shell structure, has metal ions chelated in the core, and has excellent drying speed, proper pot life, excellent liquid resistance and good mechanical properties.
Accordingly, a coating comprising: a hydroxy acrylic emulsion and a polyisocyanate;
the hydroxyl acrylic emulsion comprises: the hydroxy acrylic emulsion prepared by the preparation method or the hydroxy acrylic emulsion.
The main film forming substance of the coating provided by the invention is the hydroxyl acrylic emulsion which has a core-shell structure, metal ions are chelated in the core, and the chelated part of the metal ions and polymer molecular chains can be used as a catalyst to accelerate the reaction between isocyanate groups and hydroxyl groups, improve the actual drying speed and the crosslinking density of a paint film, and have excellent drying speed, proper working life, excellent liquid resistance and good mechanical properties.
Detailed Description
In order to make the technical problems, technical solutions and advantageous effects to be solved by the present invention more clearly apparent, the present invention is further described in detail below with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
In the description of the present invention, it is to be understood that the terms "first", "second" and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implying any number of technical features indicated. Thus, features defined as "first", "second", "third" may explicitly or implicitly include one or more of the features.
A preparation method of a hydroxyl acrylic emulsion comprises the following steps:
s01, providing a first composition and a metal precursor, wherein the first composition comprises: a first vinyl monomer containing carboxyl, wherein the metal precursor is an alkaline compound; reacting the first composition and the metal precursor to prepare a seed emulsion containing metal ions;
s02, providing a second composition of the core polymer, and reacting the seed emulsion with the second composition to prepare a core polymer emulsion;
s03, providing a third composition, reacting the core polymer emulsion with the third composition to form a shell layer on the core of the core polymer emulsion, and preparing the core-shell type hydroxy acrylic emulsion.
According to the preparation method of the hydroxyl acrylic emulsion provided by the embodiment of the invention, a first composition reacts with a metal precursor, the first composition comprises a first vinyl monomer containing carboxyl, the metal precursor can decompose metal ions under an acidic environment, and meanwhile, the metal ions can generate a chelating effect with the carboxyl in a system, so that the metal ions are chelated with polymer molecules in a seed emulsion synthesized by reaction; then, the seed emulsion is reacted with the second composition to obtain a core polymer emulsion in which metal ions are chelated, and then the core polymer emulsion is reacted with a third composition for preparing a shell polymer. The method is simple and convenient, easy to operate, free of special reagents, environment-friendly and suitable for large-scale preparation of the hydroxyl acrylic emulsion. According to the method provided by the embodiment of the invention, metal ions are introduced into the seed emulsion to prepare the hydroxy acrylic emulsion with metal ions chelated in the core, and in the film forming process, after the hydroxy acrylic emulsion particles are fully fused with the polyisocyanate curing agent, the chelated parts of the metal ions and the polymer molecular chains can be used as catalysts to accelerate the reaction between isocyanate groups and hydroxyl groups, so that the actual drying speed and the crosslinking density of a paint film can be greatly improved. Thus, the polyurethane coating prepared from the hydroxy acrylic emulsion has excellent solid drying speed, proper pot life, excellent liquid resistance and good mechanical property.
Specifically, in step S01, the metal precursor is a substance capable of providing a metal ion by a reaction, and is a basic compound. In the embodiment of the invention, the metal in the metal precursor can be chelated with carboxyl, acetoacetyl and other groups, and the formed chelate can catalyze and accelerate the reaction between isocyanate and hydroxyl so as to improve the actual drying speed of the paint film.
In one embodiment, the metal precursor is at least one of zinc oxide, zinc hydroxide, and zirconium hydroxide. The zinc oxide, zinc hydroxide, zirconium hydroxide and other metal compounds are alkaline, and can perform acid-base reaction in an acidic environment to provide metal ions for a system, and the product chelated by zinc, zirconium and carboxyl has good catalytic activity and good drying effect; meanwhile, the metal precursors have high reaction activity in an acid environment, and the obtained ion chelate is transparent and does not influence the appearance and the service performance of the emulsion.
In step S01, a first composition is used to prepare a seed emulsion, comprising: the first alkene monomer containing carboxyl provides an acid environment to promote the decomposition of metal ions from the metal precursor; on the other hand, carboxyl can generate a chelating effect with metal ions, so that the metal ions can be connected to polymer molecular chains in the seed emulsion, a precondition is provided for introducing the metal ions into the core polymer of the hydroxy acrylic emulsion particles, the activity of the reaction of the hydroxy acrylic emulsion provided by the embodiment of the invention and polyisocyanate is further improved, and the actual drying speed and the crosslinking density of a paint film are greatly improved.
In addition to the carboxyl-containing first ethylenic monomer, the first composition also includes other reactive monomers to synthesize a seed emulsion. In one embodiment, the first composition is formed by dissolving an emulsifier, a first vinyl monomer containing a carboxyl group, a second vinyl monomer selected from acrylates and/or olefins, and an initiator in water.
The emulsifier is used to improve the dispersibility of the raw materials in water to obtain a uniform seed emulsion. The emulsifier includes anionic emulsifiers and cationic emulsifiers, and in some embodiments, the emulsifier is selected from at least one of alkyl sulfonates, alkyl sulfates, alkylbenzene sulfonates, and alkyl succinates. In a further embodiment, the emulsifier is selected from sodium dodecylbenzenesulfonate.
A first vinyl monomer containing carboxyl groups and a second vinyl monomer are used as polymerized monomers for synthesizing the seed emulsion particles, and in some embodiments, the first vinyl monomer is selected from at least one of methacrylic acid, acrylic acid, and beta- (acryloyloxy) propionic acid. In some embodiments, the second diene monomer is selected from at least one of methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, isooctyl methacrylate, octadecyl methacrylate, isobornyl methacrylate, styrene.
The initiator is used for promoting the cross-linking polymerization of the first vinyl monomer and the second vinyl monomer to synthesize the seed emulsion particles. In some embodiments, the initiator is selected from at least one of ammonium persulfate, potassium persulfate, and sodium persulfate. In a further embodiment, the initiator is selected from a 4-6% by weight aqueous ammonium persulfate solution, for example, a 5% by weight aqueous ammonium persulfate solution.
In some embodiments, the weight ratio of the emulsifier, the first vinyl monomer containing carboxyl, the second vinyl monomer, the initiator and the water is (2-6): 1-4): 6-10): 10-20): 200-300. the reaction system is adopted to be beneficial to synthesizing the hydroxy acrylic emulsion of the low-hydroxyl system.
In step S01, the first composition and the metal precursor are reacted, the first composition synthesizes a seed emulsion through the reaction, and the metal precursor decomposes metal ions, and the metal ions and carboxyl groups in the system are chelated, thereby obtaining a seed emulsion containing metal ions.
As an embodiment, the step of preparing a seed emulsion containing metal ions comprises:
s011, mixing an emulsifier, the first vinyl monomer containing carboxyl, the second vinyl monomer and an initiator in water to obtain a first composition;
and S012, reacting the first composition for 15-30 minutes at 75-80 ℃, adding the metal precursor aqueous dispersion, and continuing to react for 15-30 minutes to obtain the seed emulsion containing metal ions.
The first composition is firstly subjected to preliminary reaction, and then the metal precursor is added for mixing reaction, so that metal ions decomposed from the metal precursor can be chelated and connected to a synthetic polymer molecular chain in time, and the compounding efficiency of the metal ions and the seed emulsion particles is improved. The metal precursor is added into the reaction system in the form of metal precursor water dispersion, so that the continuous reaction for synthesizing the seed emulsion ions is avoided being influenced, and the composite efficiency of the metal ions and the seed emulsion particles is favorably improved. In some embodiments, the first composition is reacted at 75 ℃ to 80 ℃ for 15 to 30 minutes.
In step S02, the second composition is used to prepare the core polymer, and a similar material system is used as the first composition, for example, the second composition is mainly based on vinyl monomers, so as to synthesize the core polymer emulsion based on the seed emulsion.
As an embodiment, the second composition comprises: a second olefin monomer and/or a first olefin monomer containing carboxyl, wherein the second olefin is selected from acrylate and/or olefin. The first vinyl monomer and the second vinyl monomer are polymerized monomers for synthesizing the seed emulsion, so that the induction effect of the seed emulsion is fully exerted, a core polymer with high compatibility with the seed emulsion is formed, and the stability of a material system is improved; meanwhile, the first vinyl monomer containing carboxyl is introduced into the second composition, so that the compounding efficiency of the core polymer and metal ions in a system can be further improved. For the specific selection of the first vinyl monomer and the second vinyl monomer in the second composition, reference may be made to the above-mentioned first composition, which is not described herein again. It is understood that the specific monomer of the first ethylenic monomer in the second composition may or may not be the same as the first ethylenic monomer used in the first composition, and the specific monomer of the second ethylenic monomer in the second composition may or may not be the same as the second ethylenic monomer used in the first composition.
As an embodiment, the second composition comprises: and a third vinyl monomer containing acetoacetoxy, wherein the third vinyl monomer is one selected from acetoacetoxy ethyl methacrylate and/or acetoacetoxy propyl methacrylate. The metal ion can be chelated with the acetoacetoxy group, and a third alkene monomer containing the acetoacetoxy group is introduced into the second composition, so that the uncarboxylated metal ion in the system is connected to the nuclear polymer; on the other hand, partial metal ions are chelated with the acetoacetic acid groups while being chelated with the carboxyl groups, so that the metal ions are promoted to be sufficiently fixed on the core, the stability is high, the reaction speed of the synthesized hydroxyacrylic acid emulsion and the polyisocyanate curing agent is remarkably improved, and the coating formed by the hydroxyacrylic acid emulsion has excellent solid drying speed.
As an embodiment, the second composition comprises: a first hydroxyalkyl acrylate. The hydroxyalkyl acrylate is a hydroxyl monomer, the hydroxyl group of the hydroxyalkyl acrylate is a primary hydroxyl group, the reactivity of the primary hydroxyl group and the isocyanate group is superior to that of a secondary hydroxyl group and a tertiary hydroxyl group, and the hydroxyalkyl acrylate is introduced into the second composition, so that the utilization rate of the hydroxyl group is improved while the number of the hydroxyl groups in the core polymer is increased, the actual drying speed of the coating can be further increased, and the production cost is reduced.
In some embodiments, the number of carbon atoms of the hydroxyalkyl groups in the first hydroxyalkyl acrylate is greater than or equal to 4. The monomer can improve the reactivity of the emulsion and the flexibility of a paint film, the distance between primary hydroxyl and a nuclear layer framework is related to the degree of freedom of the hydroxyl, and the high degree of freedom of the hydroxyl can promote the reactivity of the hydroxyl and isocyanate groups during film formation so as to further improve the utilization rate of the hydroxyl. In a further embodiment, the first hydroxyalkyl acrylate is selected from hydroxybutyl (meth) acrylate and/or hydroxyethyl (meth) acrylate.
As an embodiment, the second composition comprises: the weight ratio of the emulsifier, the first vinyl monomer containing carboxyl, the first hydroxyalkyl acrylate, the second vinyl monomer, the third vinyl monomer containing acetoacetoxy, the initiator and the water is (1-4): 2-8): 5-20): 70-300): 1-6): 50-120.
The step of reacting the seed emulsion and the second composition may be performed by referring to a conventional procedure in the art, such as some examples, in which an emulsifier, a first vinyl monomer containing a carboxyl group, a first hydroxyalkyl acrylate, a second vinyl monomer, and a third vinyl monomer containing an acetoacetoxy group are dispersed in water, and then an initiator and the seed emulsion are added within 1 to 3 hours, and then reacted at 80 to 85 ℃ for 30 to 60 minutes.
In some embodiments, the hydroxyacrylic emulsion has a glass transition temperature of the core polymer of from 10 ℃ to 60 ℃.
In step S03, the third composition for preparing the shell polymer should belong to a similar material system to the second composition, for example, vinyl monomers are used as the main component, so as to synthesize the shell polymer emulsion on the basis of the core polymer emulsion.
As an embodiment, the third composition comprises: a second vinyl monomer and/or a first vinyl monomer containing a carboxyl group. For the specific selection of the first vinyl monomer and the second vinyl monomer in the third composition, reference may be made to the above-mentioned first composition, which is not described herein again. It is understood that the specific monomer of the first olefinic monomer in the third composition may be the same or different from the first olefinic monomer used in the first composition and/or the second composition, and the specific monomer of the second olefinic monomer in the third composition may be the same or different from the second olefinic monomer used in the first composition and/or the second composition.
As an embodiment, the third composition comprises: a second hydroxyalkyl acrylate. By introducing the hydroxyalkyl acrylate containing primary hydroxyl, the number of hydroxyl in the core polymer can be increased, and the utilization rate of the hydroxyl is improved, so that the actual drying speed of the coating is further increased, and the production cost is reduced.
In some embodiments, the number of carbon atoms of the hydroxyalkyl group in the first hydroxyalkyl acrylate is greater than the number of carbon atoms of the hydroxyalkyl group in the second hydroxyalkyl acrylate. According to the characteristic that the hydroxyl acrylic emulsion and the polyisocyanate are crosslinked to form a film, the embodiment of the invention introduces the long hydroxyl side chain into the core polymer and introduces the short hydroxyl side chain into the shell polymer, so that the situation that the coating generates vitrification too early in the film forming process to prevent the curing agent from being further fused with the hydroxyl acrylic emulsion particles is avoided, the utilization rate of the hydroxyl in the hydroxyl acrylic emulsion particles is improved, the service life of the coating is prolonged, the construction convenience of the coating is improved, the production cost can be greatly reduced, and the market value is higher. The paint film thus formed has excellent solid drying speed, suitable pot life, excellent liquid resistance and good mechanical properties.
In a further embodiment, the number of carbon atoms of the hydroxyalkyl groups in the second hydroxyalkyl acrylate is less than or equal to 3.
In a further embodiment, the second hydroxyalkyl acrylate is selected from hydroxyethyl (meth) acrylate and/or hydroxypropyl (meth) acrylate.
As an embodiment, the third composition comprises: the weight ratio of the emulsifier, the first vinyl monomer containing carboxyl, the first hydroxyalkyl acrylate, the second vinyl monomer, the initiator and the water is (5-30): 20-60): 50-300): 50-120.
The step of reacting the core polymer emulsion and the third composition may be performed by referring to a conventional procedure in the art, such as in some examples, dispersing the emulsifier, the first vinyl monomer containing carboxyl group, the second hydroxyalkyl acrylate, and the second vinyl monomer in water, then adding the initiator and the core polymer emulsion within 1 to 3 hours, and then reacting at 80 to 85 ℃ for 30 to 60 minutes.
In some embodiments, the glass transition temperature of the shell polymer in the hydroxyacrylic emulsion is from 30 ℃ to 60 ℃.
As an embodiment, the step of reacting the core polymer emulsion and the third composition further comprises, after the step of: diluting the reaction product with water, adjusting the pH value of the solution to 6-8, and filtering to obtain the hydroxyl acrylic emulsion. The concentration of the emulsion is adjusted by dilution, and the pH value of the solution is adjusted to adjust the pH value of the system, so that the hydroxyl acrylic emulsion with good form is obtained. In some embodiments, in the step of adjusting the pH of the solution to 6 to 8, at least one of ammonia, dimethylethanolamine and triethylamine is used to adjust the pH of the solution.
The hydroxy acrylic emulsion prepared by the method belongs to a low-hydroxyl system, and the hydroxyl value is 10-80mg KOH/g (calculated by solid resin). In specific examples, the hydroxyl number is 10, 13, 15, 17, 21, 23, 25, 28, 30, 33, 35, 41, 46, 50, 60, 70, 80mg KOH/g (based on solid resin).
Based on the technical scheme, the embodiment of the invention provides a hydroxyl acrylic emulsion and a coating.
Correspondingly, the hydroxyl acrylic emulsion is prepared by the preparation method.
The hydroxy acrylic emulsion provided by the embodiment of the invention is prepared by the preparation method, has a core-shell structure, and metal ions are chelated in the core layer, so that in the film forming process, after hydroxy acrylic emulsion particles are fully fused with a polyisocyanate curing agent, the chelated parts of the metal ions and polymer molecular chains can be used as catalysts to accelerate the reaction between isocyanate groups and hydroxyl groups, and the actual drying speed and the crosslinking density of a paint film can be greatly improved. Thus, the polyurethane coating prepared from the hydroxyacrylic emulsion has excellent drying speed, proper pot life, excellent liquid resistance and good mechanical properties.
In one embodiment, the hydroxyl acrylic emulsion has a hydroxyl number of 10 to 80mg KOH/g (based on solid resin).
Accordingly, a coating comprising: a hydroxy acrylic emulsion and a polyisocyanate;
the hydroxyl acrylic emulsion comprises: the hydroxy acrylic emulsion prepared by the preparation method or the hydroxy acrylic emulsion.
According to the coating provided by the embodiment of the invention, the main film forming substance is the hydroxyl acrylic emulsion which has a core-shell structure, metal ions are chelated in the core layer, and the chelated parts of the metal ions and polymer molecular chains can be used as catalysts to accelerate the reaction between isocyanate groups and hydroxyl groups, so that the actual drying speed and the crosslinking density of a paint film are improved, and the coating has excellent drying speed, proper pot life, excellent liquid resistance and good mechanical properties.
As an embodiment, the polyisocyanate is selected to be a water dispersible polyisocyanate. In some embodiments, the polyisocyanate is selected from sulfonate and/or alkoxy modified hydrophilic aliphatic polyisocyanates based on hexamethylene diisocyanate.
In order that the details of the above-described practice and operation of the invention will be clearly understood by those skilled in the art, and the improved properties of a hydroxyacrylic emulsion, a method for preparing the same, and a coating material according to the examples of the present invention will be apparent, the practice of the present invention will now be illustrated by the examples.
Examples 1-3 a hydroxyacrylic emulsion was prepared having the following raw material formulation as shown in table 1 below.
TABLE 1
Figure BDA0002328751200000111
When the hydroxyacrylic acid emulsion of example 1 was prepared, component (1) was added to a reaction flask, stirring was started, the temperature was raised to 75 ℃, component (2) was added dropwise to the reaction flask over 15 minutes, the temperature was maintained for 15 minutes, component (3) was added dropwise to the reaction flask over 15 minutes, and the temperature was maintained for 30 minutes after the addition was completed, to prepare a seed emulsion. After the heat preservation is finished, uniformly mixing the raw materials of the component (5), dripping the mixture and the component (4) into the seed emulsion for about 2.5 hours, keeping the temperature at 80 ℃, and preserving the heat for 1 hour after the dripping is finished to prepare the core polymer emulsion. After the heat preservation is finished, uniformly mixing the raw materials of the component (7), dripping the raw materials and the component (6) into the nuclear polymer emulsion for about 1 hour, keeping the temperature at 85 ℃, preserving the heat for about 1 hour after the dripping is finished, then cooling to below 45 ℃, adjusting the pH value of the emulsion by using the component (8), continuing stirring for 15 minutes, and filtering and discharging by using 200-mesh filter cloth to obtain the hydroxyl acrylic emulsion.
The hydroxyacrylic emulsion of example 2 was prepared, which differs from example 1 in that: in the step of preparing the seed emulsion, the stirring is started and then the temperature is increased to 80 ℃; in the step of preparing the core polymer emulsion, the dropping time of the seed emulsion is 1.5 hours; in the step of preparing the shell polymer emulsion, the dropping time of the core polymer emulsion was 1.5 hours. The rest of the steps are substantially the same as those in embodiment 1, and are not repeated herein.
The hydroxyacrylic acid emulsion of example 3 was prepared, which differs from example 1 in that: in the step of preparing the core polymer emulsion, the dropping time of the seed emulsion is 1 hour; in the step of preparing the shell polymer emulsion, the dropping time of the core polymer emulsion was 2.5 hours. The rest of the steps are substantially the same as those in embodiment 1, and are not repeated herein.
Comparative example 1
250g of deionized water, 2.6g of sodium dodecyl benzene sulfonate and 0.8g of sodium bicarbonate are added into a reaction bottle, stirring is started, and the temperature is increased to 80 ℃. 200g of deionized water, 2.4g of ADEKA SR10 emulsifier, 96.2g of butyl acrylate, 205g of methyl methacrylate, 60g of styrene, 10g of methacrylic acid and 48.8g of hydroxyethyl methacrylate are uniformly mixed to prepare a pre-emulsion. Adding 5% of pre-emulsion into a reaction bottle, adding 16g of ammonium persulfate aqueous solution (5 wt%) into the reaction bottle within 15 minutes to initiate seed emulsion polymerization, keeping the temperature for 15 minutes, then simultaneously dropwise adding the pre-emulsion and 24g of ammonium persulfate aqueous solution (5 wt%), finishing dropwise adding within about 3 hours, and then keeping the temperature for 1 hour. And after the heat preservation is finished, cooling to below 45 ℃, diluting 2g of dimethylethanolamine by using a proper amount of deionized water, adding the dimethylethanolamine into the emulsion, stirring for 15 minutes, filtering by using 200-mesh filter cloth, and discharging. To obtain a hydroxyl acrylic emulsion having a hydroxyl value of 50mgKOH/g and a solid content of 42%.
Example 4
The embodiment provides a two-component waterborne polyurethane clear primer, which is prepared by mixing a main agent and a curing agent, wherein the curing agent is Bayhydur XP2655 curing agent, NCO: OH ═ 1.2.
The preparation method of the main agent comprises the following steps: adding the hydroxyl acrylic emulsion prepared in the embodiment 1 into a reaction kettle, sequentially adding a proper amount of film forming aids, namely dipropylene glycol methyl ether and dipropylene glycol butyl ether, a proper amount of wetting agent BYK346 and a proper amount of defoaming agent BYK024 at medium and low rotating speeds, stirring for 15 minutes, adding a proper amount of thickening agent 350D and RHEOLATE 299, a proper amount of defoaming agent Tego 810 and a proper amount of grinding aid TP 200, and stirring at a high speed for 30 minutes to obtain a main agent.
Example 5
This example differs from example 4 in that: the film forming material of the main agent is the hydroxy acrylic emulsion prepared in the example 2; the rest of the process is basically the same as that of embodiment 4, and the description is omitted here.
Example 6
This example differs from example 4 in that: the film forming material of the main agent is the hydroxy acrylic emulsion prepared in the example 3; the rest of the process is substantially the same as that of embodiment 4, and the description thereof is omitted here.
Example 7
This example differs from example 4 in that: the film-forming material of the main agent is the hydroxy acrylic emulsion prepared in comparative example 1; the rest of the process is basically the same as that of embodiment 4, and the description is omitted here.
Example 8
The embodiment provides a two-component waterborne polyurethane varnish, which is formed by mixing a main agent and a curing agent, wherein the curing agent is alkoxy-modified hydrophilic aliphatic polyisocyanate based on hexamethylene diisocyanate.
The preparation method of the main agent comprises the following steps: adding the hydroxyl acrylic emulsion prepared in the embodiment 1 into a reaction kettle, sequentially adding a proper amount of film forming aids, namely dipropylene glycol methyl ether and dipropylene glycol butyl ether, a proper amount of wetting agent BYK346 and a proper amount of defoaming agent BYK024 at medium and low rotating speeds, stirring for 15 minutes, adding a proper amount of thickening agent 350D and RHEOLATE 299 and a proper amount of defoaming agent Tego 810, and stirring at a high speed for 30 minutes to obtain a main agent.
Example 9
This example differs from example 4 in that: the film forming material of the main agent is the hydroxy acrylic emulsion prepared in the example 2; the rest of the process is basically the same as that of embodiment 4, and the description is omitted here.
Example 10
This example differs from example 4 in that: the film-forming material of the main agent is the hydroxy acrylic emulsion prepared in example 3; the rest of the process is basically the same as that of embodiment 4, and the description is omitted here.
Example 11
This example differs from example 4 in that: the film-forming material of the main agent is the hydroxy acrylic emulsion prepared in comparative example 1; the rest of the process is basically the same as that of embodiment 4, and the description is omitted here.
1. The acrylic acid hydroxy emulsion obtained in example 1 to example 3 was used for the test, and the test results are shown in Table 2.
TABLE 2
Item Example 1 Example 2 Example 3
Acid value of mgKOH/g 22.0 22.0 19.0
Hydroxyl number, mg KOH/g 43.0 54.0 60.0
Solid content (125 ℃, 1 h)% 42.0 42.0 42.0
pH(25℃) 6.6 6.8 6.5
Viscosity (25 ℃ C.), cps 80.0 75.0 115.0
2. The two-component waterborne polyurethane clear primer prepared in the examples 4 to 7 is diluted by using a proper amount of water and sprayed on walnut veneer boards, wherein the coating weight is 120- 2 And spraying three paints, wherein each primer is dried for 2 hours at 23 ℃ and 75% humidity before the next paint is sprayed, kept in a drying tunnel at 40 ℃ for 30 minutes, cooled and polished.
The two-component waterborne polyurethane clear finish prepared in the examples 8 to 11 is diluted by using proper amount of water and sprayed on the polished clear primer, and the coating weight is 120- 2 . The test performance was maintained at 23 ℃ and 75% humidity for 7 days.
Table 3 shows the test results, and as shown by the results, the hydroxyacrylic emulsion provided in the embodiment of the present invention has a suitable pot life, a fast drying speed of the coating film, a good early polishing property, a high final hardness, and a good chemical medium resistance in the compatibility of the aqueous curing agent. The two-component polyurethane coating prepared from the emulsion has the advantages of low VOC emission and low odor, and is suitable for various coating occasions with high requirements on environmental protection and comprehensive performance.
TABLE 3
Test items Example 1 Example 2 Example 3 Comparative example 1
Surface drying time, min 20 26 30 30
Actual drying time, h 2.5 2 3 4
Pot life, h 4 3.5 4 4
Sanding property of primer Easy-to-discharge powder and non-stick sand Easy-to-discharge powder and non-stick sand Easy-to-discharge powder and non-stick sand Is not easy to produce powder and stick sand
Adhesion (2 mm spacing between ruled lines), grade 1 1 1 1
Hardness of pencil HB HB F 2B
Gloss (60 degree angle) 89 88 88 87
Water resistance, 24h No abnormality No abnormality No abnormality Whitening hair
Alcohol resistance (50% ethanol), 1h No abnormality No abnormality No abnormality Whitening and swelling
Acid resistance (10% acetic acid), 1h No abnormality No abnormality No abnormality Whitening hair
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.

Claims (9)

1. The preparation method of the hydroxyl acrylic emulsion is characterized by comprising the following steps:
providing a first composition and a metal precursor, the first composition comprising: a first vinyl monomer containing carboxyl, wherein the metal precursor is an alkaline compound; reacting the first composition and the metal precursor to prepare a seed emulsion containing metal ions;
providing a second composition, and reacting the seed emulsion and the second composition to prepare a core polymer emulsion;
providing a third composition, reacting the core polymer emulsion with the third composition to form a shell layer on the core of the core polymer emulsion, and preparing a core-shell type hydroxy acrylic emulsion;
wherein the second composition comprises: a first hydroxyalkyl acrylate, said third combination comprising: a second hydroxyalkyl acrylate, the number of carbon atoms of the hydroxyalkyl group in the first hydroxyalkyl acrylate being greater than the number of carbon atoms of the hydroxyalkyl group in the second hydroxyalkyl acrylate.
2. The production method according to claim 1, wherein the metal precursor is at least one of zinc oxide, zinc hydroxide, and zirconium hydroxide.
3. The production method according to claim 1, wherein the number of carbon atoms of the hydroxyalkyl group in the first hydroxyalkyl acrylate is 4 or more; and/or
The number of carbon atoms of the hydroxyalkyl group in the second hydroxyalkyl acrylate is less than or equal to 3.
4. The method of claim 1, wherein the second composition comprises: a third vinyl monomer containing acetoacetoxy, wherein the third vinyl monomer is one of acetoacetoxy ethyl methacrylate and/or acetoacetoxy propyl methacrylate; and/or
The second composition and/or the third composition comprises: a second alkene monomer and/or the first alkene monomer containing carboxyl, wherein the second alkene is selected from acrylate and/or alkene.
5. The method according to any one of claims 1 to 4, wherein the step of preparing the seed emulsion containing the metal ion comprises:
mixing an emulsifier, the first vinyl monomer containing carboxyl, the second vinyl monomer and an initiator in water to obtain a first composition;
and (3) reacting the first composition at 75-80 ℃ for 15-30 minutes, adding the metal precursor aqueous dispersion, and continuing to react for 15-30 minutes to obtain the seed emulsion containing metal ions.
6. The method according to claim 5, wherein the emulsifier is at least one selected from alkyl sulfonate, alkyl sulfate, alkyl benzene sulfonate, and alkyl succinate; and/or
The first vinyl monomer is at least one selected from methacrylic acid, acrylic acid and beta- (acryloyloxy) propionic acid; and/or
The second diene monomer is at least one selected from methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, isooctyl methacrylate, octadecyl methacrylate, isobornyl methacrylate and styrene; and/or
The initiator is selected from at least one of ammonium persulfate, potassium persulfate and sodium persulfate.
7. A hydroxyacrylic emulsion characterized by being produced by the production method according to any one of claims 1 to 6.
8. The hydroxyacrylic emulsion of claim 7, characterized in that the hydroxyacrylic emulsion has a hydroxyl number of 10-80mg KOH/g.
9. A coating, comprising: a hydroxy acrylic emulsion and a polyisocyanate;
the hydroxyl acrylic emulsion comprises: the hydroxyacrylic emulsion obtained by the production method according to any one of claims 1 to 6, or the hydroxyacrylic emulsion according to claim 7 or 8.
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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107163177A (en) * 2017-05-02 2017-09-15 广东拓普合成科技股份有限公司 A kind of quick-dry type Hydroxylated acrylic resin aqueous dispersion of working life length and preparation method thereof
CN107722186A (en) * 2017-10-27 2018-02-23 常州华科聚合物股份有限公司 Hydroxylated acrylic resin dispersion and the water paint with its preparation

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107163177A (en) * 2017-05-02 2017-09-15 广东拓普合成科技股份有限公司 A kind of quick-dry type Hydroxylated acrylic resin aqueous dispersion of working life length and preparation method thereof
CN107722186A (en) * 2017-10-27 2018-02-23 常州华科聚合物股份有限公司 Hydroxylated acrylic resin dispersion and the water paint with its preparation

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