A modified polyester / acrylate resin hybrid aqueous dispersion and preparation method thereof, and varnish and color paint for baking varnish

Abstract

The present invention relates to a modified polyester / acrylate resin hybrid water dispersion and a preparation method thereof, as well as a varnish and a color paint for baking varnish. The water dispersion comprises a copolymer prepared from the following raw materials: modified polyester, non-functional (meth) acrylic monomer or its derivative, hydroxyl functional (meth) acrylic monomer or its derivative, carboxyl functional (meth) acrylic monomer or its derivative, styrene, and vinyl glycidyl ester. The modified polyester is used to modify the acrylic resin to obtain a water dispersion, which has excellent thermal storage stability. The amino baking varnish prepared by mixing it with an amino resin has high gloss, high chemical resistance, and excellent storage stability, while taking into account high hardness and excellent impact resistance, and can be applied to automotive coatings and other fields.

Description

Technical Field

[0001] The invention belongs to the field of water-based coatings, and particularly relates to a modified polyester / acrylate resin hybrid water dispersion and a preparation method thereof, as well as a varnish and a color paint for baking varnish. Background Art

[0002] Waterborne coatings can largely avoid the serious environmental pollution problems caused by solvent-based coatings. At the same time, under the guidance of current environmental protection policies, waterborne coatings, especially low-solvent waterborne coatings, are the inevitable trend of the current coatings industry. Waterborne hydroxy acrylic dispersions have excellent properties such as high gloss, good weather resistance, color retention and gloss retention, and are widely used in high-end coatings including automotive coatings. However, at present, hydroxy acrylic dispersions show relatively poor wetting properties for pigments and fillers, and the performance of the paint film obtained after resin grinding decreases. At the same time, its flexibility and impact resistance are relatively poor, which limits its application field to a certain extent. Polyester has good pigment and filler wetting properties, high fullness, low viscosity, good flexibility, good impact resistance and other excellent properties, which make up for the defects in the performance of acrylates. The use of polyester-modified acrylate resin dispersions can achieve the reasonable integration of polyester and acrylate to make up for their respective shortcomings and highlight their respective advantages.

[0003] CN110790869 discloses a water-based polyester copolymer prepared by reacting a saturated polyester prepolymer, an unsaturated ester and a polyacid. The processability, stability and boiling water resistance are improved by a suitable ratio of ether bonds to steric hindrance groups. However, the paint film formed by the obtained copolymer is relatively soft and cannot obtain a high hardness, which limits its application field.

[0004] US6166111 discloses an unsaturated polyester (C=C mass accounts for 0.01%-15% of the total mass of the unsaturated polyester) modified hydroxy acrylate dispersion and its preparation method. The paint film obtained from the dispersion has good gloss and resistance, but the storage stability of the finished paint obtained needs to be further improved.

[0005] US6576717 discloses a polyester-modified acrylate dispersion whose hydrophilicity is provided by sulfonate. The dispersion has good gloss, hardness and other properties, but its resistance (water resistance, acid and alkali resistance) is relatively poor.

[0006] CN102875945 prepares polyester acrylic hybrid resin by a polymerization method of mixing polyester polyol resin and acrylate monomers and then adding and mixing them simultaneously, thereby improving the compatibility of the two resins and obtaining polyester modified acrylate resin. However, the products obtained by these methods have poor water resistance and weather resistance due to the performance disadvantages of polyester itself. At the same time, the storage stability after preparing the finished paint is relatively poor.

[0007] In summary, it is necessary to provide a technology to obtain excellent storage stability, and at the same time, the paint film has high gloss, has high hardness and obtains good impact resistance, and has excellent performance in terms of durability. Summary of the invention

[0008] The present invention provides a modified polyester / acrylate resin hybrid water dispersion and a preparation method thereof. A modified polyester with a specific structure is obtained by designing the polyester structure, and the modified polyester is used to modify the acrylate resin to obtain a modified polyester / acrylate resin hybrid water dispersion, and the water dispersion has excellent heat storage stability.

[0009] The present invention also provides varnish and color paint for baking varnish, which are mixed with amino resin to prepare amino baking varnish with high gloss, high hardness and good impact resistance, as well as excellent water resistance and chemical resistance, and can be applied to automotive coatings and other fields.

[0010] In order to achieve the above technical effects, the present invention adopts the following technical solutions:

[0011] A modified polyester-acrylate resin hybrid aqueous dispersion, comprising a copolymer prepared from the following raw materials:

[0012] (A) modified polyester: 15wt%-45wt%, preferably 15wt%-35wt%,

[0013] (B) non-functional (meth) acrylic monomer or its derivative: 10 wt%-50 wt%, preferably 14 wt%-40 wt%,

[0014] (C) hydroxyl functional (meth) acrylic monomer or its derivative: 8 wt%-30 wt%, preferably 13 wt%-20 wt%,

[0015] (D) carboxyl functional (meth) acrylic monomer or its derivative: 1.5 wt%-5 wt%, preferably 2 wt%-4 wt%,

[0016] (E) styrene: 10 wt%-40 wt%, preferably 14 wt%-30 wt%,

[0017] (F) Vinyl glycidyl ester: 0.3 wt% to 5.0 wt%, preferably 0.5 wt% to 3.0 wt%.

[0018] A method for preparing a modified polyester-acrylate resin hybrid aqueous dispersion comprises the following steps:

[0019] (1) Preparation of modified polyester: a polymer of triol and ε-caprolactone, aliphatic diol and dibasic acid are subjected to condensation polymerization reaction by gradually increasing the temperature at 5-15°C / h to obtain a polymer with an acid value of 60-100 mg KOH / g, and then a diol and ε-caprolactone polymer are added to continue the reaction until the acid value is 20-40 mg KOH / g to obtain a modified polyester;

[0020] (2) preparing a hydrophobic structure copolymer by free radical polymerization: heating the modified polyester and the cosolvent to 80-150° C., then dropwise adding (B1) a non-functional (meth) acrylic monomer or a derivative thereof, (C1) a hydroxyl functional (meth) acrylic monomer or a derivative thereof, (E1) styrene and (F) vinyl glycidyl ester to polymerize to form a hydrophobic structure copolymer;

[0021] (3) in the presence of a hydrophobic copolymer, (B2) a non-functional (meth) acrylic monomer or a derivative thereof, (C2) a hydroxyl-functional (meth) acrylic monomer or a derivative thereof, (D) a carboxyl-functional (meth) acrylic monomer or a derivative thereof, and (E2) styrene are added dropwise to polymerize to form a modified polyester-acrylate resin;

[0022] (4) Neutralization and water dispersion to obtain a modified polyester-acrylate resin hybrid water dispersion.

[0023] In step (1) of the present invention, the method for preparing the polymer of triol and ε-caprolactone comprises the following steps: subjecting one or more triols such as trimethylolpropane, glycerol, and trimethylolethane to catalytic esterification reaction with ε-caprolactone at a mass ratio of 1:2-4 at 100°C-180°C.

[0024] In step (1) of the present invention, the method for preparing the polymer of diol and ε-caprolactone comprises the following steps: subjecting one or more diols such as ethylene glycol, propylene glycol, and butanediol to catalytic esterification reaction with ε-caprolactone at a mass ratio of 1:3-10 at 100°C-180°C.

[0025] In step (2) of the present invention, the total mass of the four component monomers B1, C1, E1 and F added in step (2) is taken as the basis.

[0026] (B1) non-functional (meth) acrylic monomer or its derivative: 30 wt%-80 wt%, preferably 40 wt%-70%,

[0027] (C1) hydroxyl functional (meth) acrylic monomer or its derivative: 5wt%-45wt%, preferably 10wt%-40wt%,

[0028] (E1) styrene: 10 wt%-50 wt%, preferably 15 wt%-45 wt%,

[0029] (F) Vinyl glycidyl ester: 0.5 wt%-5 wt%, preferably 1 wt%-5 wt%.

[0030] In step (2) of the present invention, the dropping time is 1.0-6.0 hours, and the temperature is kept warm for 0.3-2.0 hours after the dropping is completed.

[0031] In step (3) of the present invention, the total mass of the four component monomers B2, C2, D, and E2 added in step (3) is taken as the basis.

[0032] (B2) non-functional (meth) acrylic monomer or its derivative: 0wt%-80wt%, preferably 20wt%-70wt%,

[0033] (C2) hydroxyl functional (meth) acrylic monomer or its derivative: 5wt%-45wt%, preferably 10wt%-35wt%,

[0034] (D) carboxyl functional (meth) acrylic monomer or its derivative: 5wt%-25wt%, preferably 12wt%-20wt%,

[0035] (E2) Styrene: 0 wt% - 50 wt%, preferably 0 wt% - 30 wt%.

[0036] In step (3) of the present invention, the dropping time is 0.5-4.0 hours, and the temperature is kept warm for 0.5-2.0 hours after the dropping is completed.

[0037] The number average molecular weight of the polymer of triol and ε-caprolactone of the present invention is 250-600, preferably 300-500, and the added amount accounts for 5%-15% of the total monomer mass of the synthetic modified polyester, preferably 6%-12%.

[0038] The number average molecular weight of the polymer of diol and ε-caprolactone of the present invention is 300-1200, preferably 400-1000, and the added amount accounts for 6%-20% of the total monomer mass of the synthetic modified polyester, preferably 8%-15%.

[0039] The aliphatic diols described in the present invention include one or more of ethylene glycol, propylene glycol, butylene glycol, diethylene glycol, hexylene glycol, neopentyl glycol and 1,4-cyclohexanedimethanol.

[0040] The dibasic acid of the present invention is a composition of aromatic dibasic carboxylic acid (anhydride) and maleic anhydride, wherein the maleic anhydride accounts for 5%-10% of the total mass of the dibasic acid.

[0041] The aromatic dicarboxylic acid (anhydride) of the present invention includes one or more of isophthalic acid and phthalic acid (anhydride).

[0042] The vinyl glycidyl ester of the present invention includes at least one of glycidyl methacrylate and glycidyl acrylate, and its content is 0.5wt%-5.0wt% of the total weight of B, C, D, E and F.

[0043] The number average molecular weight of the modified polyester of the present invention is 1000-5000, preferably 1000-3000, the hydroxyl value range is 50-250 mg KOH / g, and the added amount accounts for 15wt%-45wt% of the total amount of the modified polyester-acrylate resin.

[0044] As a preferred embodiment, step (2) of the present invention is carried out in the presence of an initiator, wherein the initiator is a peroxide free radical initiator, preferably one or more of di-tert-butyl peroxide, di-tert-amyl peroxide, and benzoyl peroxide, more preferably di-tert-butyl peroxide and / or di-tert-amyl peroxide, and the amount of the initiator accounts for 1.0wt%-5.0wt% of the total weight of B1, C1, E1, and F, preferably 2.0wt%-3.0wt%.

[0045] As a preferred embodiment, step (3) of the present invention is carried out in the presence of an initiator, wherein the initiator is a peroxide free radical initiator, preferably one or more of di-tert-butyl peroxide, di-tert-amyl peroxide, and benzoyl peroxide, more preferably di-tert-butyl peroxide and / or di-tert-amyl peroxide, and the amount of the initiator accounts for 1.0wt%-5.0wt% of the total weight of B2, C2, D, and E2, preferably 2.0wt%-3.0wt%.

[0046] The non-functional (meth)acrylic monomer or its derivatives described in the present invention include one or more of methyl (meth)acrylate, butyl (meth)acrylate, ethyl (meth)acrylate, isooctyl (meth)acrylate, dodecyl (meth)acrylate, isobornyl (meth)acrylate, and norbornyl (meth)acrylate.

[0047] The hydroxyl-functional (meth)acrylic monomer or its derivatives described in the present invention include one or more of hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, and hydroxyhexyl (meth)acrylate.

[0048] The carboxyl functional (meth) acrylic monomer or its derivatives described in the present invention include one or more of (meth) acrylic acid, crotonic acid, and maleic acid.

[0049] In step (4) of the present invention, the neutralizing agent used for neutralization includes one or more of ammonia water, sodium hydroxide, triethanolamine, and N,N-dimethylethanolamine, and the degree of neutralization is 80-120%.

[0050] The modified polyester / acrylate resin hybrid water dispersion of the present invention is suitable for application in water-based coatings, and is particularly suitable for use in combination with an amine curing agent to prepare high-performance baking varnish, and is applied to the fields of automotive paint and the like.

[0051] A varnish for baking varnish comprises the following components: by weight, 50.0-65.0 parts of a modified polyester / acrylate hybrid aqueous dispersion, 7.0-11 parts of an amino resin, 11.6-28.5 parts of deionized water, 0.1-0.3 parts of a neutralizer, 0.2-0.8 parts of a defoamer, 0.1-0.5 parts of a wetting agent, 3.0-10.0 parts of a cosolvent, and 0.3-0.8 parts of a thickener.

[0052] A color paint for baking varnish comprises the following components: by weight, 35-60 parts of modified polyester / acrylate hybrid water dispersion, 6.0-10.0 parts of amino resin, 15-40 parts of pigment, 0-20 parts of filler, 0.1-1.0 parts of dispersant, 10-20 parts of deionized water, 0.1-0.3 parts of neutralizer, 0.2-0.8 parts of defoamer, 0.1-1.0 parts of wetting and leveling agent, 5-12 parts of cosolvent and 0.1-0.5 parts of thickener.

[0053] The amino resin of the present invention is selected from one or more of methyl etherified high imine melamine resin and fully methyl etherified melamine resin, wherein the methyl etherified high imine melamine resin includes CYMEL325, CYMEL327 and the like, and the fully methyl etherified melamine resin includes CYMEL303, Resimene747 and the like.

[0054] The neutralizing agent of the present invention is selected from one or more of N,N-dimethylethanolamine, AMP-95, triethylamine and triethanolamine, preferably N,N-dimethylethanolamine or AMP-95.

[0055] The defoaming agent of the present invention is selected from one or more of TEGO FOAMEX830, BYK025, BYK028, AD01, BYK011, BYK024, Tego1488, Tego904w, and Tego902, preferably one or more of TEGO FOAMEX830, AD01, BYK011, and BYK028.

[0056] The wetting agent of the present invention is selected from one or more of polyether-modified siloxanes or polyacrylates, preferably one or more of Surfynol 104E, Tego 4100, and Tego 270.

[0057] The cosolvent of the present invention is selected from one or more of ethylene glycol butyl ether, n-butanol, diethylene glycol butyl ether, propylene glycol butyl ether, dipropylene glycol butyl ether, dipropylene glycol methyl ether, propylene glycol methyl ether acetate, and ethylene glycol butyl ether acetate, preferably ethylene glycol butyl ether and diethylene glycol butyl ether.

[0058] The thickener of the present invention is selected from one or more of polyurethane associative thickeners, polyacrylate thickeners, and cellulose thickeners, preferably one or more of BYK425, U905, U505, and RHEOLATE299.

[0059] The dispersant described in the present invention is selected from one or more of DISPERBYK190, DISPERBYK191, DISPERBYK192, DISPERBYK2012, and Tego755.

[0060] The pigment of the present invention is selected from one or more pigments known in the art such as carbon black, titanium dioxide, iron oxide red, titanium cyanine blue, and iron oxide yellow.

[0061] The filler described in the present invention is selected from one or more fillers known in the art such as barium sulfate, calcium carbonate, mica, kaolin, zinc sulfate, and aluminum phosphate.

[0062] The present invention provides a modified polyester / acrylate resin hybrid water dispersion and a preparation method thereof. By designing the polyester structure, the crosslinking point is softened by using ε-caprolactone to obtain a polycaprolactone soft segment, so as to obtain excellent impact resistance. In addition, moderate crosslinking significantly improves chemical resistance. At the same time, the hard segment of phthalic anhydride polyester is used to obtain a higher hardness, so as to obtain a modified polyester with high hardness and better impact resistance, and the modified polyester is used to carry out a graft reaction on acrylic resin to improve the compatibility of the two, so as to obtain a modified polyester / acrylate resin hybrid water dispersion with excellent stability. When the water dispersion is used in the field of baking varnish, it has high gloss, high chemical resistance, and excellent storage stability, while taking into account high hardness and excellent impact resistance. DETAILED DESCRIPTION

[0063] The following examples will further illustrate the method provided by the present invention, but the present invention is not limited to the listed examples, and should also include any other known changes within the scope of the claims of the present invention.

[0064] Number average molecular weight determination: GPC (gel permeation chromatography) was used for number average molecular weight test. Hydroxyl value determination: Under reflux conditions of 115°C, the hydroxyl value was esterified with phthalic anhydride dissolved in pyridine, and the excess phthalic anhydride was titrated with a standard sodium hydroxide solution to determine the hydroxyl value.

[0065] DBG: diethylene glycol butyl ether, Dow Chemical, USA;

[0066] BCS: ethylene glycol butyl ether, Dow Chemical, USA;

[0067] DMEA: N,N-dimethylethanolamine, BASF, Germany;

[0068] DTBP: di-tert-butyl peroxide, Lanzhou Additive Factory;

[0069] CHDM: 1,4-cyclohexanedimethanol, Jiangshan Chemical;

[0070] Embodiment 1:

[0071] 268 g of trimethylolpropane, 684 g of ε-caprolactone and 0.2 g of isopropyl titanate were added into a reactor containing a heating device, a condensing device, a stirring device and a negative pressure device, nitrogen was passed through and the temperature was raised to 130°C for reaction for 4.0 hours to obtain a polymer P1-1 with a number average molecular weight of 476 and a hydroxyl value of 353 mg KOH / g.

[0072] 268 g of trimethylolpropane, 456 g of ε-caprolactone and 0.2 g of isopropyl titanate were added into a reactor containing a heating device, a condensing device, a stirring device and a negative pressure device, nitrogen was passed through and the temperature was raised to 130°C for reaction for 4.0 hours to obtain polymer P1-2, which had a number average molecular weight of 362 and a hydroxyl value of 464 mg KOH / g.

[0073] Embodiment 2:

[0074] 760 g of propylene glycol, 6840 g of ε-caprolactone and 0.5 g of isopropyl titanate were added into a reactor containing a heating device, a condensing device, a stirring device and a negative pressure device, nitrogen was passed through and the temperature was raised to 140°C for reaction for 4.0 hours to obtain a polymer P2-1 with a number average molecular weight of 760 and a hydroxyl value of 147 mg KOH / g.

[0075] 900 g of 1,4-butanediol, 7980 g of ε-caprolactone and 0.5 g of isopropyl titanate were added into a reactor containing a heating device, a condensing device, a stirring device and a negative pressure device, nitrogen was passed through and the temperature was raised to 130°C for reaction for 4.0 hours to obtain a polymer P2-2 having a number average molecular weight of 890 and a hydroxyl value of 125 mg KOH / g.

[0076] Embodiment 3:

[0077] 146g of polymer P1-1 (obtained in Example 1), 600g of CHDM, 700g of phthalic anhydride, and 50g of maleic anhydride were added to a reactor containing a heating device, a condensing device, a stirring device, and a negative pressure device, nitrogen was passed through, the temperature was raised to 150°C, stirring was started, and the reaction was continued until reflux dehydration occurred, and then the temperature was gradually raised to 220°C at 10°C / hour for condensation polymerization to obtain a polyester resin with an acid value of 60mg KOH / g, and then 146g of polymer P2-1 (obtained in Example 2) was added and the reaction was continued until the acid value was 20mg KOH / g to obtain a modified polyester. The number average molecular weight of the obtained modified polyester was 2536; the hydroxyl value was 62mg KOH / g.

[0078] 50g DBG and 146g modified polyester were added together into a 1L reactor containing a heating device, a condensing device and a stirring device and heated to 140°C. When the initial material was heated to 140°C, the following monomer mixture was uniformly added dropwise: 35g methyl methacrylate, 82g butyl acrylate, 81g hydroxyethyl methacrylate, 82g styrene, 12g glycidyl methacrylate and 8.8g DTBP. The addition time was about 3 hours. After the monomer mixture was added dropwise, it was kept at this temperature for 20 minutes. Then the following monomer mixture was uniformly added dropwise: 14g methyl methacrylate, 46g butyl acrylate, 32g hydroxyethyl methacrylate, 14g acrylic acid and 3.0g DTBP. The addition time was about 1 hour. After the monomer mixture was added dropwise, it was kept at this temperature for 1 hour. Then 17.3g DMEA was added and stirred for 20 minutes. Then, 580g pure water was used to disperse for 10 minutes to obtain a modified polyester / acrylate resin hybrid water dispersion.

[0079] Embodiment 4:

[0080] 100g of polymer P1-2 (obtained in Example 1), 700g of CHDM, 680g of phthalic anhydride, and 40g of maleic anhydride were added to a reactor containing a heating device, a condensing device, a stirring device, and a negative pressure device, nitrogen was passed through, the temperature was raised to 150°C, stirring was started, and the reaction was continued until reflux dehydration occurred, and then the temperature was gradually raised to 220°C at 10°C / hour for condensation polymerization to obtain a polyester resin with an acid value of 100mg KOH / g, and then 160g of polymer P2-2 (obtained in Example 2) was added and the reaction was continued until the acid value reached 30mg KOH / g to obtain a modified polyester. The number average molecular weight of the obtained modified polyester was 1374; the hydroxyl value was 102mg KOH / g.

[0081] 60g BCS and 80g modified polyester were added together into a 1L reactor containing a heating device, a condensing device and a stirring device and heated to 140°C. When the initial material was heated to 140°C, the following monomer mixture was uniformly added dropwise: 14g methyl methacrylate, 107g isooctyl acrylate, 42g hydroxypropyl acrylate, 130g styrene, 3g glycidyl methacrylate and 6.5g DTBP. The addition time was about 3 hours. After the monomer mixture was added dropwise, it was kept at this temperature for 20 minutes. Then the following monomer mixture was uniformly added dropwise: 20g methyl methacrylate, 34g butyl acrylate, 32g hydroxypropyl acrylate, 18g acrylic acid and 2.3g DTBP. The addition time was about 1 hour. After the monomer mixture was added dropwise, it was kept at this temperature for 1 hour. Then 18g DMEA was added and stirred for 20 minutes. Then, 540g pure water was used to disperse for 10 minutes to obtain a modified polyester / acrylate resin hybrid water dispersion.

[0082] Comparative Example 1:

[0083] 2.3g trimethylolpropane, 1.3g propylene glycol, 22.4g ε-caprolactone, 62g phthalic anhydride, 53g CHDM, 4.4g maleic anhydride were added to a reactor containing a heating device, a condensing device, a stirring device and a negative pressure device, nitrogen was passed through, the temperature was raised to 150°C, stirring was started, the reaction was continued until reflux dehydration, and then the temperature was gradually raised to 220°C at 10°C / hour for condensation polymerization reaction to obtain a modified polyester with an acid value of 20mg KOH / g. The number average molecular weight of the obtained modified polyester was 2472; the hydroxyl value was 68mg KOH / g.

[0084] 50g DBG and 146g modified polyester were added together into a 1L reactor containing a heating device, a condensing device and a stirring device and heated to 140°C. When the initial material was heated to 140°C, the following monomer mixture was uniformly added dropwise: 35g methyl methacrylate, 82g butyl acrylate, 81g hydroxyethyl methacrylate, 82g styrene, 12g glycidyl methacrylate and 8.8g DTBP. The addition time was about 3 hours. After the monomer mixture was added dropwise, it was kept at this temperature for 20 minutes. Then the following monomer mixture was uniformly added dropwise: 14g methyl methacrylate, 46g butyl acrylate, 32g hydroxyethyl methacrylate, 14g acrylic acid and 3.0g DTBP. The addition time was about 1 hour. After the monomer mixture was added dropwise, it was kept at this temperature for 1 hour. Then 17.3g DMEA was added and stirred for 20 minutes. Then, 580g pure water was used to disperse for 10 minutes to obtain a modified polyester / acrylate resin hybrid water dispersion.

[0085] Comparative Example 2:

[0086] 100g of polymer P1-2 (obtained in Example 1), 160g of polymer P2-2 (obtained in Example 2), 700g of CHDM, 680g of phthalic anhydride, and 40g of maleic anhydride were added to a reactor containing a heating device, a condensing device, a stirring device, and a negative pressure device, nitrogen was passed through, the temperature was raised to 150°C, stirring was started, the reaction was continued until reflux and dehydration occurred, and then the temperature was gradually raised to 220°C at 10°C / hour for condensation polymerization to obtain a polyester resin with an acid value of 30mg KOH / g. The number average molecular weight of the obtained modified polyester was 1256; the hydroxyl value was 112mg KOH / g.

[0087] 60g BCS and 80g modified polyester were added to a 1L reactor with a heating device, a condensing device and a stirring device and heated to 140°C. When the initial material was heated to 140°C, the following monomer mixture was uniformly added dropwise: 14g methyl methacrylate, 107g isooctyl acrylate, 42g hydroxypropyl acrylate, 130g styrene, 3g glycidyl methacrylate and 6.5g DTBP. The addition time was about 3 hours. After the monomer mixture was added dropwise, it was kept at this temperature for 20 minutes. Then the following monomer mixture was uniformly added dropwise: 20g methyl methacrylate, 34g butyl acrylate, 32g hydroxypropyl acrylate, 18g acrylic acid and 2.3g DTBP. The addition time was about 1 hour. After the monomer mixture was added dropwise, it was kept at this temperature for 1 hour. Then 18g DMEA was added and stirred for 20 minutes. Then, 540g pure water was used to disperse for 10 minutes to obtain a modified polyester / acrylate hybrid aqueous dispersion.

[0088] Comparative Example 3:

[0089] 134 g of trimethylolpropane, 114 g of ε-caprolactone and 0.1 g of isopropyl titanate were added into a reactor containing a heating device, a condensing device, a stirring device and a negative pressure device, nitrogen was passed through and the temperature was raised to 130°C for reaction for 4.0 hours to obtain polymer P1-3, which had a number average molecular weight of 225 and a hydroxyl value of 693 mg KOH / g.

[0090] 146g of polymer P1-3, 600g of CHDM, 700g of phthalic anhydride, and 50g of maleic anhydride were added to a reactor containing a heating device, a condensing device, a stirring device, and a negative pressure device, nitrogen was passed through, the temperature was raised to 150°C, stirring was started, and the reaction was continued until reflux dehydration occurred, and then the temperature was gradually raised to 220°C at 10°C / hour for condensation polymerization to obtain a polyester resin with an acid value of 60mg KOH / g, and then 146g of polymer P2-1 was added to continue the reaction until the acid value reached 20mgKOH / g to obtain a modified polyester. The number average molecular weight of the obtained modified polyester was 1542; the hydroxyl value was 95mg KOH / g.

[0091] 50g DBG and 146g modified polyester were added together into a 1L reactor containing a heating device, a condensing device and a stirring device and heated to 140°C. When the initial material was heated to 140°C, the following monomer mixture was uniformly added dropwise: 35g methyl methacrylate, 82g butyl acrylate, 81g hydroxyethyl methacrylate, 82g styrene, 12g glycidyl methacrylate and 8.8g DTBP. The addition time was about 3 hours. After the monomer mixture was added dropwise, it was kept at this temperature for 20 minutes. Then the following monomer mixture was uniformly added dropwise: 14g methyl methacrylate, 46g butyl acrylate, 32g hydroxyethyl methacrylate, 14g acrylic acid and 3.0g DTBP. The addition time was about 1 hour. After the monomer mixture was added dropwise, it was kept at this temperature for 1 hour. Then 17.3g DMEA was added and stirred for 20 minutes. Then, 580g pure water was used to disperse for 10 minutes to obtain a modified polyester / acrylate hybrid aqueous dispersion.

[0092] Comparative Example 4:

[0093] 180 g of 1,4-butanediol, 3600 g of ε-caprolactone and 0.3 g of isopropyl titanate were added to a reactor containing a heating device, a condensing device, a stirring device and a negative pressure device, nitrogen was passed through and the temperature was raised to 140°C for reaction for 4.0 hours to obtain polymer P2-3, which had a number average molecular weight of 1350 and a hydroxyl value of 83 mg KOH / g.

[0094] 146g polymer P1-1, 600g CHDM, 700g phthalic anhydride, 50g maleic anhydride were added to a reactor containing a heating device, a condensing device, a stirring device and a negative pressure device, nitrogen was passed through, the temperature was raised to 150°C, stirring was started, the reaction was continued until reflux dehydration, and then the temperature was gradually raised to 220°C at 10°C / hour for condensation polymerization to obtain a polyester resin with an acid value of 60mg KOH / g, and then 146g polymer P2-3 was added to continue the reaction until the acid value was 20mgKOH / g to obtain a modified polyester. The number average molecular weight of the obtained modified polyester was 3017; the hydroxyl value was 58mg KOH / g.

[0095] 50g DBG and 146g modified polyester were added together into a 1L reactor containing a heating device, a condensing device and a stirring device and heated to 140°C. When the initial material was heated to 140°C, the following monomer mixture was uniformly added dropwise: 35g methyl methacrylate, 82g butyl acrylate, 81g hydroxyethyl methacrylate, 82g styrene, 12g glycidyl methacrylate and 8.8g DTBP. The addition time was about 3 hours. After the monomer mixture was added dropwise, it was kept at this temperature for 20 minutes. Then the following monomer mixture was uniformly added dropwise: 14g methyl methacrylate, 46g butyl acrylate, 32g hydroxyethyl methacrylate, 14g acrylic acid and 3.0g DTBP. The addition time was about 1 hour. After the monomer mixture was added dropwise, it was kept at this temperature for 1 hour. Then 17.3g DMEA was added and stirred for 20 minutes. Then, 580g pure water was used to disperse for 10 minutes to obtain a modified polyester / acrylate hybrid aqueous dispersion.

[0096] Application Testing

[0097] 125g of modified polyester / acrylate resin hybrid aqueous dispersion, 30g of deionized water and 6.0g of BYK190 dispersant (BYK, Germany) were added into a dispersion tank and stirred at 600r / min for 3min. Then, 0.5g of neutralizer AMP95 (Dow), 3g of wetting agent Surfynol104E (American Gas Chemical) and 0.5g of defoaming agent Tego830 (Germany Tego) were added in sequence while stirring and stirring was continued for 10min. Then, 190g of titanium dioxide R-706 (DuPont) was added and stirring was continued for 15min. Finally, 400g of zirconium beads were added and the speed was increased to 3000r / min and stirring was continued for 3 hours. After filtering, the fineness was tested to be <10u to obtain a white slurry.

[0098] First, add 4.5g CYMEL325 (80% solid content, Allnex), 2.0g Resimene747 (97% solid content, Ineos) and 1.0g n-butanol, 1.5g BCS and 4.5g DBG into the dispersion tank and stir at 600r / min for 5min to mix evenly. Then, add 42g modified polyester / acrylate resin hybrid water dispersion, 7.4g deionized water, 0.2g AMP95 and 36g white slurry in turn and continue stirring for 10min. Then, add 0.2g catalyst NACURE in turn. X49-110 (King's Industries, USA), 0.3g wetting agent and leveling agent Tego270 (Diego, Germany), 0.2g wetting and leveling agent BYK381 (BYK, Germany), 0.2g defoaming agent BYK025 (BYK, Germany) and continue stirring for 10 minutes, finally add 0.2g thickener Rheolate299 (Hemmings) and continue stirring for 10 minutes to obtain the finished white paint.

[0099] The viscosity of the obtained finished white paint was adjusted to a viscosity of 30-35 seconds for coating 4 cups, and then sprayed onto the substrate. After being placed at room temperature for 10 minutes, it was placed in a 140°C oven and baked for 25 minutes to obtain a sample, and the performance of the sample was tested. The results are shown in Table 1.

[0100] Table 1 Performance test results

[0101]

[0102] Comparative Examples 1 and 2 do not have the structural design of the present invention. In Comparative Example 1, the polymerization monomers are added together, the structure obtained by the reaction cannot be controlled, the cross-linking point cannot have a softening effect, and at the same time, the phthalic anhydride hardness cannot be obtained to improve the hardness, and a high-hardness baking varnish cannot be obtained. In Comparative Example 2, the cross-linked soft segment and the polycaprolactone soft segment are added together to react, and it is possible to obtain a further softening structure for the cross-linking point, but a higher hardness cannot be obtained. The soft segment molecular weight in Comparative Examples 3 and 4 is not within the scope of the present invention, the molecular weight is large, the hardness is low, the molecular weight is small, and the impact performance is poor, and a sample with high hardness and good impact resistance cannot be obtained.

[0103] Finally, it should be noted that the above embodiments are only used to describe the preferred implementation methods of the present invention, rather than to limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, ordinary technicians in the field should understand that various modifications and improvements made by modifying or equivalently replacing the technical solution of the present invention should fall within the protection scope determined by the claims of the present invention.

Claims

1. A modified polyester-acrylate resin hybrid aqueous dispersion, comprising a copolymer prepared from the following raw materials: (A) modified polyester: 15wt%-45wt%, (B) non-functional (meth) acrylic monomer or its derivative: 10wt%-50wt%, (C) hydroxyl functional (meth) acrylic monomer or its derivative: 8wt%-30wt%, (D) carboxyl functional (meth) acrylic monomer or its derivative: 1.5wt%-5wt%, (E) Styrene: 10wt%-40wt%, (F) vinyl glycidyl ester: 0.3wt%-5.0wt%; The preparation method of the modified polyester-acrylate resin hybrid aqueous dispersion comprises the following steps: (1) Preparation of modified polyester: a triol and a polymer of ε-caprolactone, an aliphatic diol and a dibasic acid are subjected to condensation polymerization to obtain a polymer having an acid value of 60-100 mg KOH / g, and then a diol and a polymer of ε-caprolactone are added to continue the reaction until the acid value is 20-40 mg KOH / g to obtain a modified polyester; (2) preparing a hydrophobic structure copolymer by free radical polymerization: heating the modified polyester and the cosolvent to 80-150° C., then dropwise adding (B1) a non-functional (meth) acrylic monomer or a derivative thereof, (C1) a hydroxyl functional (meth) acrylic monomer or a derivative thereof, (E1) styrene and (F) vinyl glycidyl ester to polymerize to form a hydrophobic structure copolymer; (3) in the presence of a hydrophobic copolymer, (B2) a non-functional (meth) acrylic monomer or a derivative thereof, (C2) a hydroxyl-functional (meth) acrylic monomer or a derivative thereof, (D) a carboxyl-functional (meth) acrylic monomer or a derivative thereof, and (E2) styrene are added dropwise to polymerize to form a modified polyester-acrylate resin; (4) neutralizing and dispersing in water to obtain a modified polyester-acrylate resin hybrid aqueous dispersion; The number average molecular weight of the polymer of the triol and ε-caprolactone is 250-600; the number average molecular weight of the polymer of the diol and ε-caprolactone is 300-1200.

2. The modified polyester-acrylate resin hybrid aqueous dispersion according to claim 1, characterized in that: It contains copolymers prepared from the following raw materials: (A) modified polyester: 15wt%-35wt%, (B) non-functional (meth) acrylic monomer or its derivative: 14 wt%-40 wt%, (C) hydroxyl functional (meth) acrylic monomer or its derivative: 13 wt%-20 wt%, (D) carboxyl functional (meth) acrylic monomer or its derivative: 2wt%-4wt%, (E) Styrene: 14 wt% -30 wt%, (F) Vinyl glycidyl ester: 0.5 wt% - 3.0 wt%.

3. The modified polyester-acrylate resin hybrid aqueous dispersion according to claim 1, characterized in that: The addition amount of the polymer of triol and ε-caprolactone accounts for 5%-15% of the total monomer mass of the synthetic modified polyester; the triol includes one or more of trimethylolpropane, glycerol and trimethylolethane.

4. The modified polyester-acrylate resin hybrid aqueous dispersion according to claim 3, characterized in that: The number average molecular weight of the polymer of triol and ε-caprolactone is 300-500, and the added amount accounts for 6%-12% of the total monomer mass of the synthesized modified polyester.

5. The modified polyester-acrylate resin hybrid aqueous dispersion according to claim 1, characterized in that: The added amount of the polymer of diol and ε-caprolactone accounts for 6%-20% of the total monomer mass of the synthesized modified polyester; the diol includes one or more of ethylene glycol, propylene glycol and butanediol.

6. The modified polyester-acrylate resin hybrid aqueous dispersion according to claim 5, characterized in that: The number average molecular weight of the polymer of diol and ε-caprolactone is 400-1000, and the added amount accounts for 8%-15% of the total monomer mass of the synthesized modified polyester.

7. The modified polyester-acrylate resin hybrid aqueous dispersion according to claim 1, characterized in that: In the step (2), the total mass of the four component monomers B1, C1, E1 and F added in the step (2) is taken as the basis. (B1) non-functional (meth) acrylic monomer or its derivative: 30 wt%-80 wt%, (C1) hydroxyl functional (meth) acrylic monomer or its derivative: 5wt%-45wt%, (E1) Styrene: 10wt%-50wt%, (F) Vinyl glycidyl ester: 0.5 wt% - 5 wt%.

8. The modified polyester-acrylate resin hybrid aqueous dispersion according to claim 1, characterized in that: In the step (2), the total mass of the four component monomers B1, C1, E1 and F added in the step (2) is taken as the basis. (B1) non-functional (meth) acrylic monomer or its derivative: 40wt%-70%, (C1) hydroxyl functional (meth) acrylic monomer or its derivative: 10wt%-40wt%, (E1) Styrene: 15wt%-45wt%, (F) Vinyl glycidyl ester: 1 wt% - 5 wt%.

9. The modified polyester-acrylate resin hybrid aqueous dispersion according to claim 1, characterized in that: In the step (3), the total mass of the four component monomers B2, C2, D, and E2 added in the step (3) is taken as the basis. (B2) non-functional (meth) acrylic monomer or its derivative: 0wt%-80wt%, (C2) hydroxyl functional (meth) acrylic monomer or its derivative: 5wt%-45wt%, (D) carboxyl functional (meth) acrylic monomer or its derivative: 5wt%-25wt%, (E2) Styrene: 0 wt% - 50 wt%.

10. The modified polyester-acrylate resin hybrid aqueous dispersion according to claim 1, characterized in that: In the step (3), the total mass of the four component monomers B2, C2, D, and E2 added in the step (3) is taken as the basis. (B2) non-functional (meth) acrylic monomer or its derivative: 20wt%-70wt%, (C2) hydroxyl functional (meth) acrylic monomer or its derivative: 10 wt%-35 wt%, (D) carboxyl functional (meth) acrylic monomer or its derivative: 12 wt%-20 wt%, (E2) Styrene: 0 wt% - 30 wt%.

11. The modified polyester-acrylate resin hybrid aqueous dispersion according to claim 1, characterized in that: The vinyl glycidyl ester includes at least one of glycidyl methacrylate and glycidyl acrylate, and its content is 0.5wt%-5.0wt% of the total weight of the non-functional (meth)acrylic monomer or its derivative, the hydroxyl-functional (meth)acrylic monomer or its derivative, the carboxyl-functional (meth)acrylic monomer or its derivative, styrene and vinyl glycidyl ester in step (2) and step (3).

12. The modified polyester-acrylate resin hybrid aqueous dispersion according to claim 1, characterized in that: The number average molecular weight of the modified polyester is 1000-5000, and the hydroxyl value ranges from 50-250 mg KOH / g.

13. The modified polyester-acrylate resin hybrid aqueous dispersion according to claim 12, characterized in that: The number average molecular weight of the modified polyester is 1000-3000.

14. A varnish for baking varnish, comprising the following components: In parts by weight, the modified polyester-acrylate resin hybrid aqueous dispersion according to any one of claims 1 to 12 is 50.0-65.0 parts, the amino resin is 7.0-11 parts, the deionized water is 11.6-28.5 parts, the neutralizer is 0.1-0.3 parts, the defoamer is 0.2-0.8 parts, the wetting agent is 0.1-0.5 parts, the cosolvent is 3.0-10.0 parts, and the thickener is 0.3-0.8 parts.

15. A color paint for baking varnish, comprising the following components: In parts by weight, the modified polyester-acrylate resin hybrid aqueous dispersion according to any one of claims 1 to 12 is 35-60 parts, the amino resin is 6.0-10.0 parts, the pigment is 15-40 parts, the filler is 0-20 parts, the dispersant is 0.1-1.0 parts, the deionized water is 10-20 parts, the neutralizer is 0.1-0.3 parts, the defoamer is 0.2-0.8 parts, the wetting and leveling agent is 0.1-1.0 parts, the cosolvent is 5-12 parts, and the thickener is 0.1-0.5 parts.

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