Microgel dispersion and preparation method thereof

Abstract

The invention discloses a microgel dispersion and a preparation method thereof, the dispersion can be selectively cross-linked, is obtained by free radical dispersion polymerization in an aliphatic hydrocarbon solvent, and comprises polymer nanoparticles of an ethylenically unsaturated monomer, a soluble dispersant for stabilizing the particles and a hydrocarbon continuous phase. The particle size of the dispersoid is 100-400 nm, the dispersoid has high refractive index, and the material provided by the invention is suitable for a coating composition based on a film-forming polymer, such as thermosetting acrylic resin or alkyd resin containing an aromatic hydrocarbon or aliphatic hydrocarbon solvent.

Description

Technical Field

[0001] The invention belongs to the technical field of automobile coating materials, and particularly relates to a microgel dispersion and a preparation method thereof. Background Art

[0002] Microgel dispersions are dispersions with particles of about 0.01 to 0.8 microns stably dispersed in organic solvents (mainly aliphatic hydrocarbons). They have advantages over conventional solution-based resins in terms of low pollution, resource saving, and coating construction. In Europe and the United States, it has been used in large quantities by major automobile manufacturers. Practical applications in China have also begun. For automotive coatings using microgel dispersions, they have excellent rheological properties during construction, and exhibit excellent anti-sagging properties in one-coat-one-bake (1C1B) and two-coat-one-bake (2C1B) series coatings, especially for automotive topcoats. In addition, as a 2C1B clearcoat coating, it has sufficient practical value as a high-solids component, and compared with traditional solvent-based coatings, it exhibits unique coating properties such as drying, durability, and solvent resistance.

[0003] An important component for controlling particle size during the polymerization of microgel dispersions is the dispersant, which can stabilize highly polar polymer particles in less polar solvents. The average chain length, composition and functional groups of the dispersant are important characteristics. Low molecular weight dispersants contain reactive double bonds, which allow the dispersant chains to covalently bond to the microgel particles, which is beneficial to their dispersing and stabilizing effects. The morphology of the dispersant incorporated into the growing chain affects the growth and stability of the particles. The epoxy groups of glycidyl (meth)acrylate are reacted with a copolymer composed of (meth)acrylic acid and its ester units containing carboxyl groups, and the double bonds are randomly distributed between the chains. Since the position of the double bonds in the dispersant chain is not controlled, multiple attachment sites of the dispersant on the particle surface will occur.

[0004] By using a cobalt chain transfer agent in the free radical polymerization process to synthesize poly(meth)acrylic acid and its esters, each chain end contains a double bond, which is more effective than a dispersant with double bonds randomly grafted at any position of the main chain. The terminal double bond type dispersant can extend from its anchor point on the particle into the solvent, thereby providing excellent dispersion stability. Summary of the invention

[0005] The object of the present invention is to provide a microgel dispersion and a preparation method thereof.

[0006] To achieve the above-mentioned purpose and other related purposes, the technical scheme provided by the present invention is: a soluble dispersant, wherein the raw material formula of the soluble dispersant comprises the following raw materials in parts by weight: 15-50 parts of xylene, 5-20 parts of prepolymer, 20-80 parts of drop material A, 2-20 parts of drop material B, and 0.01-0.15 parts of terminator; the drop material A is composed of at least one of acrylic acid and its ester monomers, vinyl monomers and nitrile monomers mixed with an initiator; the drop material B is composed of N ,N',N",N"'-(tetrafluoroborate)bis[M-(2,3-butanedione oxime)]cobalt(II) and bis(difluorodiphenylethylenedioxime boronate)cobalt are mixed with toluene to form the prepolymer; the raw material formula of the prepolymer includes the following raw materials in parts by weight: 45-70 parts of 2-hydroxystearic acid, 20-60 parts of xylene, 0.05-3 parts of p-toluenesulfonic acid, 2-12 parts of glycidyl methacrylate and 0.01-1 parts of 2-(dimethylamino)isobutanol.

[0007] The preferred technical solution is: the acrylic acid and its ester monomers are at least one of methyl acrylate, n-butyl acrylate, methyl methacrylate, n-butyl methacrylate, isooctyl acrylate, isooctyl methacrylate, lauryl acrylate, lauryl methacrylate, acrylic acid, allyl (meth)acrylate, glycol di(meth)acrylate, divinylbenzene, hexanediol diacrylate, neopentyl glycol diacrylate, tripropylene glycol diacrylate and methacrylic acid.

[0008] The preferred technical solution is: the vinyl monomer is at least one of styrene and N-phenyl substituted maleimide.

[0009] The preferred technical solution is: the nitrile monomer is acrylonitrile.

[0010] The preferred technical solution is: the terminator is catechol, and the initiator is tert-butyl peroxyethylhexanoate.

[0011] The preferred technical scheme is: the preparation method of the prepolymer comprises: adding 2-hydroxystearic acid, xylene, and p-toluenesulfonic acid into a reaction container, heating until the acid value is 31-35 mgKOH / g; then cooling, and adding glycidyl methacrylate and 2-(dimethylamino)isobutanol, reacting until the acid value is less than or equal to 1 mgKOH / g, to obtain a dispersant prepolymer.

[0012] To achieve the above-mentioned purpose and other related purposes, the technical scheme provided by the present invention is: a method for preparing a soluble dispersant, characterized in that: it comprises: heating xylene and prepolymer to 120-160°C, then adding drop material A and drop material B to the reaction system within 100-300 minutes, and keeping warm for 10-60 minutes after the addition is completed; then adding a terminator to terminate the reaction; and then keeping at the reaction temperature for 50-200 minutes, and then cooling to room temperature to obtain a soluble dispersant.

[0013] To achieve the above-mentioned purpose and other related purposes, the technical solution provided by the present invention is: a microgel dispersion, characterized in that: the raw material formula of the microgel dispersion includes the following raw materials in parts by weight: 15-50 parts of hydrocarbon solvent, 3-10 parts of the soluble dispersant described in any one of claims 1-6, 3-20 parts of the first drop material, 20-80 parts of the second drop material, 1-8 parts of the third drop material, and 1-9 parts of the fourth drop material; the first drop material includes an initiator and methyl methacrylate, the second drop material includes at least one of styrene, butyl acrylate, methacrylic acid, hydroxyethyl acrylate, divinylbenzene and hexanediol diacrylate and an initiator; the third drop material includes a chain transfer agent and a hydrocarbon solvent; the fourth drop material includes an initiator and a hydrocarbon solvent.

[0014] The preferred technical solution is: the initiator is at least one of tert-butyl peroxyethylhexanoate, di-tert-butyl peroxide and azobisisoheptanenitrile; and the chain transfer agent is dodecanethiol.

[0015] A preferred technical solution is that the dispersed polymer in the microgel dispersion is insoluble in the dispersion medium in a dispersed state, and the solubility parameter difference between the dispersed polymer and the hydrocarbon solvent is greater than or equal to 2.

[0016] To achieve the above-mentioned and other related purposes, the technical solution provided by the present invention is: a method for preparing a microgel dispersion, characterized in that it comprises the following steps:

[0017] Step 1: Add a hydrocarbon solvent and a soluble dispersant into a reaction container, raise the temperature to 80-95°C, then add the first drop of feed, add it within 5-20 minutes, and keep it warm for 5-30 minutes;

[0018] Step 2: After the heat preservation is completed, add the second and third drops of feed, add them within 100-300 minutes, then add the fourth drop of feed, add them within 5-20 minutes, keep warm for 0.5-2 hours, cool to room temperature, and obtain a microgel dispersion.

[0019] The preferred technical solution is: the hydrocarbon solvent is at least one of n-hexane, n-heptane and n-nonane.

[0020] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0021] 1. The soluble dispersant prepared by the present invention is an amphiphilic polymer (hydrophilic and lipophilic polymer) polymerized by two different polar components, which has a lower polarity than the dispersion particles, and the reactive double bond is connected to the end of each dispersant molecule through chain transfer. The molecular weight Mw of the dispersant is less than 10000Da. During the dispersion polymerization process, it is connected to the polar chain of the dispersion particles by covalent bonds and distributed on the surface of the dispersion particles in a more stable manner, which plays a role in preventing flocculation and controlling particle size.

[0022] 2. The microgel dispersion of the present invention uses a soluble dispersant as a steric hindrance stabilizer to form protective micelles, and uses a peroxide free radical initiator or an azo initiator to initiate free radical polymerization of ethylenically unsaturated monomers in the protective micelles to obtain a microgel dispersion.

[0023] 3. The present invention uses a cobalt chain transfer agent in the process of synthesizing poly(meth)acrylic acid and its esters by free radical polymerization, so that each chain end contains a double bond, which is more effective than a dispersant with double bonds randomly grafted at any position of the main chain. The terminal double bond type dispersant can extend from its anchor point on the particle into the solvent, thereby providing excellent dispersion stability.

[0024] 4. The microgel dispersion of the present invention can be selectively cross-linked and is obtained by free radical dispersion polymerization in an aliphatic hydrocarbon solvent, comprising: polymer nanoparticles of olefinically unsaturated olefin monomers, a soluble dispersant for stabilizing the particles, and a hydrocarbon continuous phase. The dispersion particles have a particle size of 100 to 400 nm and a high refractive index. The material of the present invention is suitable for use in coating compositions based on film-forming polymers, such as thermosetting acrylic resins or alkyd resins containing aromatic or aliphatic hydrocarbon solvents. DETAILED DESCRIPTION

[0025] The following is a description of the implementation of the present invention by means of specific embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in the embodiments.

[0026] Unless otherwise specified, the experimental materials used in the following examples were purchased from conventional biochemical reagent stores.

[0027] Example 1: A method for preparing a soluble dispersant

[0028] The preparation method of the soluble dispersant is as follows:

[0029] Table 1 Prepolymer

[0030] Element Weight 12-Hydroxystearic acid 53.5 Xylene 39.6 p-Toluenesulfonic acid 0.2 Glycidyl Methacrylate 6.5 2-(Dimethylamino)isobutanol 0.2

[0031] Table 2 Soluble dispersant 1

[0032]

[0033]

[0034] First, prepare the dispersant prepolymer. According to Table 1, add 12-hydroxystearic acid, xylene, and p-toluenesulfonic acid into a reaction bottle, and heat it to 150°C until the acid value reaches 31-35 mgKOH / g. Then cool it to 140°C, add glycidyl methacrylate and 2-(dimethylamino)isobutyl alcohol, and react until the acid value is less than 1 mgKOH / g to obtain a dispersant prepolymer.

[0035] According to Table 2, the base material was added to the reactor and heated to 140°C, and then the drop material A and the drop material B were added dropwise to the reactor at a constant rate for 240 minutes, and then kept for 30 minutes. Then, the terminator was added to terminate the reaction. The reaction temperature was kept for 120 minutes, and then cooled to room temperature to obtain a soluble dispersant 1.

[0036] Example 2: A method for preparing a soluble dispersant

[0037] The preparation method of the soluble dispersant is as follows:

[0038] Table 3 Soluble dispersant 2

[0039]

[0040]

[0041] The dispersant prepolymer is the same as that in Example 1.

[0042] According to Table 3, the base material was added to the reactor and heated to 140°C, and then the drop material A and the drop material B were added dropwise to the reactor at a constant rate for 240 minutes, and then kept for 30 minutes. Then, the terminator was added to terminate the reaction. The reaction temperature was kept for 120 minutes, and then cooled to room temperature to obtain a soluble dispersant 2.

[0043] Example 3: A microgel dispersion and a method for preparing the same

[0044] The preparation method of microgel dispersion is as follows:

[0045] Table 4: Microgel dispersion 1

[0046] Element Weight Base material n-Heptane 32 Soluble dispersant 1 8 First drop addition Azobis(2-isoheptanonitrile) 1 Methyl Methacrylate 8 Second drop addition Styrene 12 Butyl acrylate 17 Methacrylic acid 5 Hydroxyethyl acrylate 4.7 Hexanediol diacrylate 2.5 Azobis(2-isoheptanonitrile) 2 The third addition Dodecanethiol 0.8 n-Heptane solvent 3 Fourth drop of feed Azobis(2-isoheptanonitrile) 1 n-Heptane 3

[0047] In the first step, a base material is added to the reactor, wherein the soluble dispersant is from Example 1, and the temperature is raised to 90°C, followed by the addition of the first drop of material, which is added within 10 minutes and kept warm for 15 minutes; in the second step, the second drop of material and the third drop of material are added to the reactor, which are added within 180 minutes, and then the fourth drop of material is added, which are added within 10 minutes, kept warm for 1 hour, and cooled to room temperature to obtain a microgel dispersion 1.

[0048] Example 4: A microgel dispersion and a method for preparing the same

[0049] The preparation method of microgel dispersion is as follows:

[0050] Table 5 Microgel dispersion 2

[0051] Element Weight Base material n-Heptane 32 Soluble dispersant 2 8 First drop addition Azobis(2-isoheptanonitrile) 1 Methyl Methacrylate 8 Second drop addition Styrene 12 Butyl acrylate 17 Methacrylic acid 5 Hydroxyethyl acrylate 4.7 Hexanediol diacrylate 2.5 Azobis(2-isoheptanonitrile) 2 The third addition Dodecanethiol 0.8 n-Heptane 3 Fourth drop of feed Azobis(2-isoheptanonitrile) 1 n-Heptane 3

[0052] The first step is to add the base material into the reactor, wherein the soluble dispersant is from Example 2, and heat it to 90°C, then add the first drop of material, drip it within 10 minutes, and keep it warm for 15 minutes; the second step is to add the second drop of material and the third drop of material into the reactor, drip it within 180 minutes, then add the fourth drop of material, drip it within 10 minutes, keep it warm for 1 hour, and cool it to room temperature to obtain microgel dispersion 2.

[0053] Example 5: A microgel dispersion and a method for preparing the same

[0054] The preparation method of microgel dispersion is as follows:

[0055] Table 6: Microgel Dispersion 3

[0056] Element Weight Base material n-Heptane 32 Soluble dispersant 2 8 First drop addition Azobis(2-isoheptanonitrile) 1 Methyl Methacrylate 8 Second drop addition Styrene 12 Butyl acrylate 17 Methacrylic acid 5 Hydroxyethyl acrylate 4.7 Divinylbenzene 2.5 Azobis(2-isoheptanonitrile) 2 The third addition Dodecanethiol 0.8 n-Heptane 3 Fourth drop of feed Azobis(2-isoheptanonitrile) 1 n-Heptane 3

[0057] In the first step, a base material is added to the reactor, wherein the soluble dispersant is from the embodiment, and the temperature is raised to 90°C, followed by the addition of the first drop of material, which is added within 10 minutes and kept warm for 15 minutes; in the second step, the second drop of material and the third drop of material are added to the reactor, which are added within 180 minutes, and then the fourth drop of material is added, which are added within 10 minutes, kept warm for 1 hour, and cooled to room temperature to obtain microgel dispersion 3.

[0058] Comparative Example 1

[0059] The preparation method of the soluble dispersant is as follows:

[0060] Table 7 Soluble dispersant 3

[0061]

[0062]

[0063] The dispersant prepolymer was prepared according to Example 1.

[0064] According to Table 4, the base material was added to the reactor and heated to 140°C, and then the drop material A and the drop material B were added dropwise to the reactor at a constant rate for 240 minutes, and then kept for 30 minutes. Then, the terminator was added to terminate the reaction. The reaction temperature was kept for 120 minutes, and then cooled to room temperature to obtain a soluble dispersant 3.

[0065] The preparation method of microgel dispersion is as follows:

[0066] Table 8: Microgel Dispersion 4

[0067]

[0068]

[0069] In the first step, the base material is added into the reactor, the temperature is raised to 90°C, and then the drop material A is added, the addition is completed within 10 minutes, and the temperature is kept for 15 minutes. In the second step, the drop materials B and C are added into the reactor, the addition is completed within 180 minutes, and then the drop material D is added, the addition is completed within 10 minutes, the temperature is kept for 1 hour, and the temperature is cooled to room temperature to obtain microgel dispersion 4.

[0070] Experimental Results

[0071] The microgel dispersion was stored at 50°C for 14 days and then evaluated for appearance, fineness and particle size.

[0072] Table 9: Storage stability results

[0073] project Example 3 Example 4 Example 5 Comparative Example 1 Appearance Unstratified Unstratified Unstratified Slight delamination Fineness <5μm 10μm <5μm 50μm Particle size 78nm 105nm 84nm 213nm

[0074] As can be seen from the above table, compared with the microgel dispersions of the present invention (Examples 3, 4, and 5), Comparative Example 1 in which no Co(II) dispersion stabilizer is used exhibits relatively poor storage stability.

[0075] The above description is only used to explain the preferred embodiments of the present invention, and is not intended to limit the present invention in any form. Therefore, any modifications or changes made to the present invention under the same inventive spirit should still be included in the scope of protection intended by the present invention.

Claims

1. A soluble dispersant, characterized in that: The raw material formula of the soluble dispersant comprises the following raw materials in parts by weight: 15-50 parts of xylene, 5-20 parts of prepolymer, 20-80 parts of drop material A, 2-20 parts of drop material B, and 0.01-0.15 parts of terminator; the drop material A is composed of at least one of acrylic acid and its ester monomers, vinyl monomers and nitrile monomers mixed with an initiator; the drop material B is composed of at least one of N,N',N",N"'-(tetrafluoroborate)bis[M-(2,3-butanedione oxime)]cobalt (II) and bis(boronated difluorodiphenylethylenedioxime)cobalt mixed with toluene; the raw material formula of the prepolymer comprises the following raw materials in parts by weight: 45-70 parts of 2-hydroxystearic acid, 20-60 parts of xylene, 0.05-3 parts of p-toluenesulfonic acid, 2-12 parts of glycidyl methacrylate and 0.01-1 parts of 2-(dimethylamino)isobutanol.

2. The soluble dispersant according to claim 1, characterized in that: The acrylic acid and its ester monomers are at least one of methyl acrylate, n-butyl acrylate, methyl methacrylate, n-butyl methacrylate, isooctyl acrylate, isooctyl methacrylate, lauryl acrylate, lauryl methacrylate, acrylic acid, allyl (meth)acrylate, glycol di(meth)acrylate, divinylbenzene, hexanediol diacrylate, neopentyl glycol diacrylate, tripropylene glycol diacrylate and methacrylic acid.

3. The soluble dispersant according to claim 1, characterized in that: The vinyl monomer is at least one of styrene and N-phenyl substituted maleimide.

4. The soluble dispersant according to claim 1, characterized in that: The nitrile monomer is acrylonitrile.

5. The soluble dispersant according to claim 1, characterized in that: The terminator is catechol, and the initiator is tert-butyl peroxyethylhexanoate.

6. The soluble dispersant according to claim 1, characterized in that: The preparation method of the prepolymer comprises: adding 2-hydroxystearic acid, xylene and p-toluenesulfonic acid into a reaction container, heating until the acid value is 31-35 mgKOH / g; then cooling, adding glycidyl methacrylate and 2-(dimethylamino)isobutyl alcohol, reacting until the acid value is less than or equal to 1 mgKOH / g, and obtaining a dispersant prepolymer.

7. A method for preparing a soluble dispersant according to any one of claims 1 to 6, characterized in that: include: Heat xylene and prepolymer to 120-160°C, then add dropwise material A and dropwise material B to the reaction system within 100-300 minutes, and keep warm for 10-60 minutes after the addition is completed; then add a terminator to terminate the reaction; then keep at the reaction temperature for 50-200 minutes, and then cool to room temperature to obtain a soluble dispersant.

8. A microgel dispersion, characterized in that: The raw material formula of the microgel dispersion includes the following raw materials in parts by weight: 15-50 parts of hydrocarbon solvent, 3-10 parts of the soluble dispersant described in any one of claims 1-6, 3-20 parts of the first drop material, 20-80 parts of the second drop material, 1-8 parts of the third drop material, and 1-9 parts of the fourth drop material; the first drop material includes an initiator and methyl methacrylate, the second drop material includes at least one of styrene, butyl acrylate, methacrylic acid, hydroxyethyl acrylate, divinylbenzene and hexanediol diacrylate and an initiator; the third drop material includes a chain transfer agent and a hydrocarbon solvent; and the fourth drop material includes an initiator and a hydrocarbon solvent.

9. The microgel dispersion according to claim 8, characterized in that: The initiator is at least one of tert-butyl peroxyethylhexanoate, di-tert-butyl peroxide and azobisisoheptanenitrile; and the chain transfer agent is dodecanethiol.

10. The microgel dispersion according to claim 8, characterized in that: The dispersed polymer in the microgel dispersion is insoluble in the dispersion medium in a dispersed state, and the solubility parameter difference between the dispersed polymer and the hydrocarbon solvent is greater than or equal to 2.

11. A method for preparing the microgel dispersion according to claim 8, characterized in that: The following steps are involved: Step 1: Add a hydrocarbon solvent and a soluble dispersant into a reaction container, raise the temperature to 80-95°C, then add the first drop of feed, add it within 5-20 minutes, and keep it warm for 5-30 minutes; Step 2: After the heat preservation is completed, add the second and third drops of feed, add them within 100-300 minutes, then add the fourth drop of feed, add them within 5-20 minutes, keep warm for 0.5-2 hours, cool to room temperature, and obtain a microgel dispersion.

12. The method for preparing a microgel dispersion according to claim 11, characterized in that: The hydrocarbon solvent is at least one of n-hexane, n-heptane and n-nonane.

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