CN114958161A - Water-based polyester coating liquid for protective coating and preparation method and application thereof - Google Patents
Water-based polyester coating liquid for protective coating and preparation method and application thereof Download PDFInfo
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- 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
- C09D167/00—Coating compositions based on polyesters obtained by reactions forming a carboxylic ester link in the main chain; Coating compositions based on derivatives of such polymers
- C09D167/02—Polyesters derived from dicarboxylic acids and dihydroxy compounds
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- 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
- C08G63/00—Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
- C08G63/64—Polyesters containing both carboxylic ester groups and carbonate groups
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- 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
- C08G63/00—Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
- C08G63/68—Polyesters containing atoms other than carbon, hydrogen and oxygen
- C08G63/688—Polyesters containing atoms other than carbon, hydrogen and oxygen containing sulfur
- C08G63/6884—Polyesters containing atoms other than carbon, hydrogen and oxygen containing sulfur derived from polycarboxylic acids and polyhydroxy compounds
- C08G63/6886—Dicarboxylic acids and dihydroxy compounds
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J7/00—Chemical treatment or coating of shaped articles made of macromolecular substances
- C08J7/04—Coating
- C08J7/0427—Coating with only one layer of a composition containing a polymer binder
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- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
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- C08J7/00—Chemical treatment or coating of shaped articles made of macromolecular substances
- C08J7/04—Coating
- C08J7/046—Forming abrasion-resistant coatings; Forming surface-hardening coatings
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- 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
- C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
- C09D5/08—Anti-corrosive paints
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- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
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- C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
- C09D7/20—Diluents or solvents
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- 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
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- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2369/00—Characterised by the use of polycarbonates; Derivatives of polycarbonates
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- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2467/00—Characterised by the use of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Derivatives of such polymers
- C08J2467/02—Polyesters derived from dicarboxylic acids and dihydroxy compounds
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
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Abstract
The invention provides a water-based polyester coating liquid for a protective coating, and a preparation method and application thereof, wherein the preparation raw materials of the water-based polyester coating liquid comprise water-based polyester, a closed curing agent, a film-forming aid, butanone and water, and the mole percentage content of water-based monomers in synthetic monomers of the water-based polyester is not higher than 5% and not equal to 0. According to the invention, butanone is added into the raw materials for preparation as a pretreatment agent, and the waterborne polyester is successfully dissolved or dispersed into a waterborne polyester dispersion liquid by water under the condition that the molar percentage of the waterborne monomer is not higher than 5%, so that the lowest content of the waterborne monomer is realized, and the obtained waterborne polyester coating liquid has excellent water resistance, alkali resistance and solvent resistance after being formed into a film, and also has higher hardness and higher base material adhesion, and is particularly suitable for being used as a protective coating of a polycarbonate base material.
Description
Technical Field
The invention belongs to the technical field of coating liquid, and particularly relates to a water-based polyester coating liquid for a protective coating, and a preparation method and application thereof.
Background
Polycarbonate (PC) is a high molecular polymer containing carbonate groups in molecular chains, and has very good optical performance, stronger impact resistance and explosion resistance; in addition, the flame-retardant glass can be used as a very good transparent material to replace glass or organic glass, and has the advantages of light weight, convenience in installation, high strength, strong plasticity, strong flame retardant property and the like. However, the polycarbonate material has poor wear resistance, water resistance, solvent resistance and antifogging property, and generally needs to be provided with a protective coating on the surface.
At present, the protective coating can be divided into three categories, namely organic coatings, organic/inorganic hybrid coatings and inorganic coatings according to different compositions of protective coating materials. The organic coating is roughly divided into two types, one type is a polyurethane coating, and the wear resistance is improved through the elasticity and certain self-healing characteristic of the organic coating; the other is a silicone and acrylic coating, which increases the hardness of the coating by a higher crosslink density. The organic/inorganic hybrid coating is roughly divided into three types, one is that inorganic nano particles are directly added into organic resin and cured to form the organic/inorganic hybrid coating; secondly, preparing an organic/inorganic hybrid coating by a thermosetting sol-gel method; the other method is ultraviolet light curing to obtain a sol-gel organic/inorganic hybrid coating; the inorganic coating is mostly prepared into a protective coating on the surface of the polycarbonate by methods such as chemical vapor deposition, sputtering, physical deposition and the like. However, the preparation processes of the coatings are generally complicated, the VOC of the prepared coating liquid is high, and the transparency and stability of the coatings are poor.
The problem of high VOC content of the coating liquid can be solved by the appearance of the aqueous coating liquid, most of the existing aqueous coating liquids are aqueous emulsions or aqueous dispersions, the number of the existing aqueous coating liquids is two, and due to the fact that the existing aqueous coating liquids contain a high proportion of auxiliaries or emulsifiers, the formed coating thickness is large, the glossiness is low, and meanwhile, the defects of water resistance, scratch resistance, high temperature and high humidity resistance and the like are overcome.
CN114308588A discloses a composite material prepared by using waterborne polyurethane as a surface layer and a middle layer, using a solvent-free foaming layer (polyester polyol, isocyanate prepolymer, calcium carbonate and the like) as an adhesive layer and a PC film, wherein the prepared product has the characteristics of no solvent residue and low odor, and simultaneously has the characteristics of high bonding strength and good damp-heat resistance and water boiling resistance because the adhesive layer is bonded with the PC film through a chemical bond. However, the product prepared by the process has a multilayer structure and a complex preparation process, and the transparency of the coating is poor due to the filler component contained in the product.
CN109666119A discloses an aqueous antifogging resin, a preparation method thereof and an antifogging coating composition with the aqueous antifogging resin, wherein a molecular chain segment and a functional group with good hydrophilicity and hygroscopicity are introduced into the aqueous antifogging resin, so that the technical problem that an organic solvent is required to be added in the preparation process of a high polymer coating and the high polymer coating is not an aqueous coating is solved. However, the number average molecular weight of the water-based antifogging resin obtained in the patent is high and reaches 50000-10000, and the hardness of the formed water-based antifogging coating is low (< 1H), so that when the water-based antifogging resin is used as a protective coating of polycarbonate, the polycarbonate substrate cannot be effectively protected.
Therefore, the development of an aqueous polyester coating solution having excellent water resistance, alkali resistance, high hardness and excellent adhesion to a substrate after film formation is still one of the major problems in the field.
Disclosure of Invention
In view of the defects of the prior art, the invention aims to provide an aqueous polyester coating liquid for a protective coating layer, a preparation method and application thereof, wherein the aqueous polyester coating liquid has excellent water resistance, alkali resistance, corrosion resistance, higher hardness and excellent adhesion performance with a polycarbonate substrate after film formation; and the solvent of the water-based polyester coating liquid is water, so that the water-based polyester coating liquid has ultra-low VOC (volatile organic compounds) emission and excellent environmental protection characteristic.
In order to achieve the purpose, the invention adopts the following technical scheme:
in a first aspect, the invention provides a water-based polyester coating liquid for a protective coating, which is prepared from the raw materials of water-based polyester, a closed curing agent, a film-forming aid, butanone and water;
the mole percentage of the water-based monomer in the synthetic monomers of the water-based polyester is not higher than 5% and not equal to 0, such as 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, etc.
The waterborne polyester coating liquid provided by the invention is added with the waterborne polyester, and the mole percentage content of the waterborne monomer in the synthetic monomer of the waterborne polyester is limited to be not higher than 5% and not equal to 0, and because the water-based polyester synthesized by adopting the low-water-based monomer is difficult to be directly dissolved or dispersed by water, butanone is added in the preparation raw materials of the coating liquid, the butanone is used as a pretreatment solvent, the water-based polyester is pretreated into a clear and transparent solution by adopting the butanone in the preparation process, and then the butanone is replaced by water, further successfully dissolving or dispersing the water-based polyester into water-based polyester dispersion liquid under the condition of ensuring that the mole percentage content of the water-based monomer is lower, so that the obtained water-based polyester coating liquid has clear and transparent appearance, the film has excellent water resistance, solvent resistance, alkali resistance and higher hardness and transparency after being formed; meanwhile, the butanone is completely replaced by water in the preparation process, so that the solvent of the finally provided aqueous polyester coating liquid is only water, and the coating liquid has low VOC content and excellent environmental protection property.
Preferably, the number average molecular weight of the aqueous polyester is not less than 20000, for example 22000, 24000, 26000, 28000, 30000, 32000, 34000, 36000, 38000, or the like.
Preferably, the synthetic monomers of the aqueous polyester include structural monomers and aqueous monomers.
Preferably, the aqueous monomer comprises any one of or a combination of at least two of dimethyl isophthalate-5-sodium sulfonate, isophthalic acid-5-sodium sulfonate or succinic anhydride sulfonic acid.
Preferably, the mole percentage of the water-based monomer in the synthetic monomer of the water-based polyester is 0.5-5%.
As a preferable technical scheme of the invention, the molar percentage of the water-based monomer in the synthetic monomer of the water-based polyester is limited to 0.5-5%, so that the finally obtained water-based polyester coating liquid has more excellent comprehensive performance. On one hand, if the mole percentage of the aqueous monomer is less than 0.5%, the synthesized aqueous polyester is difficult to be uniformly dispersed in water, and a uniformly dispersed aqueous polyester dispersion cannot be obtained, so that the performance of a coating liquid prepared subsequently is influenced; on the other hand, if the molar percentage of the aqueous monomer is more than 5%, the water resistance, alkali resistance and solvent resistance of the finally obtained aqueous polyester coating solution after film formation are deteriorated, and the hardness is lowered.
Preferably, the structural monomers include dibasic acid monomers and dihydric alcohol monomers.
Preferably, the dibasic acid monomer comprises a dicarboxylic acid and/or an esterified product of a dicarboxylic acid.
Preferably, the dicarboxylic acid comprises terephthalic acid and/or isophthalic acid.
Preferably, the esterified product of the dicarboxylic acid comprises dimethyl terephthalate and/or dimethyl isophthalate.
Preferably, the diol monomer comprises any one or a combination of at least two of polycarbonate diol, neopentyl glycol, ethylene glycol or 1, 4-cyclohexanedimethanol, and is further preferably polycarbonate diol.
The preparation method of the water-based polyester is not specially limited in the invention, and the water-based polyester can be synthesized according to the existing method.
Illustratively, the preparation method of the water-based polyester comprises the following steps: putting a structural monomer, a water-based monomer and a catalyst into a stainless steel reaction kettle, mixing under the protection of nitrogen, rapidly heating to 100-150 ℃, fully mixing, gradually heating to 180 ℃, reacting for no less than 2 hours, heating to 220-240 ℃, reacting for no less than 2.5 hours, ending the reaction when the esterification rate is more than 95%, finally adding triethyl phosphorylacetate (80-100 ppm) and antimony trioxide (10-30 ppm), continuously heating, slowly reducing the pressure, adjusting the rotating speed to 60rpm, controlling the temperature to be 235-250 ℃, gradually reducing the pressure to be below 100Pa, carrying out polycondensation reaction, stopping stirring when the viscosity of a polymer reaches 0.7-0.85 dl/g, and removing vacuum to obtain the water-based polyester.
Preferably, the blocked curing agent comprises a blocked aqueous isocyanate curing agent.
Preferably, the deblocking temperature of the blocked curing agent is not lower than 80 ℃, such as 82 ℃, 84 ℃, 86 ℃, 88 ℃, 90 ℃, 92 ℃, 94 ℃, 96 ℃, 98 ℃ or 100 ℃, and the like.
In the invention, the blocked curing agent is preferably one or more of Asahi chemical conversion aqueous HDI VM44-L70G or Bayer XP2706 and XP 2802.
Preferably, the coalescing agent has a boiling point of no less than 250 ℃, e.g., 252 ℃, 254 ℃, 256 ℃, 258 ℃, 260 ℃, 262 ℃, 264 ℃, 266 ℃, 268 ℃, or 270 ℃, and the like.
Preferably, the content of the film-forming aid in the aqueous polyester coating liquid is not more than 1% by mass, for example, 0.9%, 0.85%, 0.8%, 0.75%, 0.7%, 0.65%, 0.6%, 0.55%, 0.5%, or the like.
Preferably, the coalescing agent comprises any one of or a combination of at least two of triethylene glycol monobutyl ether, tetrahydrofuran dimethanol or tripropylene glycol n-butyl ether.
Preferably, the preparation raw materials of the aqueous polyester coating liquid comprise the following components in parts by weight:
wherein the aqueous polyester may be 53 parts by weight, 56 parts by weight, 59 parts by weight, 62 parts by weight, 65 parts by weight, 68 parts by weight, 71 parts by weight, 74 parts by weight, 77 parts by weight, or the like.
The blocked curing agent may be 2.2 parts by weight, 2.4 parts by weight, 2.6 parts by weight, 2.8 parts by weight, 3 parts by weight, 3.2 parts by weight, 3.4 parts by weight, 3.6 parts by weight, 3.8 parts by weight, 4 parts by weight, 4.2 parts by weight, 4.4 parts by weight, 4.6 parts by weight, or 4.8 parts by weight, etc.
The coalescing agent can be 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, or 1.9 parts by weight, and the like.
The butanone may be 110 parts by weight, 120 parts by weight, 130 parts by weight, 140 parts by weight, 150 parts by weight, 160 parts by weight, 170 parts by weight, 180 parts by weight, 190 parts by weight, or the like.
The water may be 133 parts by weight, 136 parts by weight, 139 parts by weight, 142 parts by weight, 145 parts by weight, 148 parts by weight, 151 parts by weight, 154 parts by weight, 157 parts by weight, or the like.
Preferably, the preparation raw materials of the aqueous polyester coating liquid further comprise any one or a combination of at least two of a leveling agent, a defoaming agent and a wetting agent.
In the invention, the leveling agent is preferably one or more of BYK-190, BYK-333 or BYK-024 as a birk auxiliary agent.
In the invention, the wetting agent is preferably one or more of BYK-345, BYK-3520 or Tego Wet270 and 280.
In the invention, the defoaming agent is used for reducing or preventing the generation of bubbles, and is preferably one or more of BYK-017, BYK-028, BYK-1770 or Cognis 2293 and 4100.
In a second aspect, the present invention provides a method for preparing an aqueous polyester coating solution as described in the first aspect, the method comprising the steps of:
(1) mixing water-based polyester and butanone, adding water, and heating to remove the butanone to obtain a water-based polyester dispersion liquid;
(2) adding a blocked curing agent into the aqueous polyester dispersion liquid obtained in the step (1) for mixing, and then adding a film-forming aid, an optional defoaming agent, an optional leveling agent and an optional wetting agent for mixing to obtain the aqueous polyester coating liquid.
The preparation method provided by the invention comprises the steps of firstly pretreating the water-based polyester into a clear and transparent solution by using butanone, removing the butanone by heating, replacing the butanone with water, finally successfully obtaining a uniform and stable water-based polyester dispersion liquid, finally uniformly mixing the obtained water-based polyester dispersion liquid and a closed curing agent, adding a film-forming aid, optionally an antifoaming agent, optionally a leveling agent and optionally a wetting agent, and mixing to obtain the water-based polyester coating liquid.
Preferably, the mixing temperature in step (1) is not higher than 60 ℃, such as 59 ℃, 58 ℃, 57 ℃, 56 ℃, 55 ℃, 54 ℃, 53 ℃, 52 ℃, 51 ℃ or 50 ℃, etc.
Preferably, the water is added in step (1) in a stepwise manner.
Preferably, the temperature raising rate in the step (1) is 1-2 ℃/min, such as 1.1 ℃/min, 1.2 ℃/min, 1.3 ℃/min, 1.4 ℃/min, 1.5 ℃/min, 1.9 ℃/min, 1.7 ℃/min, 1.8 ℃/min or 1.9 ℃/min, and the like.
Preferably, the temperature of the system after the temperature rise in the step (1) is 90 to 95 ℃, for example, 90.5 ℃, 91 ℃, 91.5 ℃, 92 ℃, 92.5 ℃, 93 ℃, 93.5 ℃, 94 ℃ or 94.5 ℃.
Preferably, the mixing time for adding the blocked curing agent and mixing in the step (2) is 50 to 70 ℃, for example, 52 ℃, 54 ℃, 56 ℃, 58 ℃, 60 ℃, 62 ℃, 64 ℃, 66 ℃ or 68 ℃.
Preferably, the mixing time for adding the blocked curing agent in the step (2) for mixing is 30-60 min, such as 33min, 36min, 39min, 42min, 45min, 48min, 51min, 54min or 57 min.
Preferably, the isocyanate index of the system after the addition and mixing of the blocked curing agent in the step (2) is 1.05 to 1.1, such as 1.06, 1.07, 1.08 or 1.09.
Preferably, the mixing time for further mixing the film forming aid, the optional defoaming agent, the optional leveling agent and the optional wetting agent in the step (2) is 30-60 min, such as 33min, 36min, 39min, 42min, 45min, 48min, 51min, 54min or 57 min.
As a preferred technical scheme of the invention, the preparation method comprises the following steps:
(1) mixing water-based polyester and butanone into a clear and transparent state at the temperature of not higher than 60 ℃, gradually adding water, heating to 90-95 ℃ at the heating rate of 1-2 ℃/min to remove the butanone, and stopping heating to obtain a water-based polyester dispersion liquid;
(2) adding a closed curing agent into the aqueous polyester dispersion liquid obtained in the step (1), mixing for 30-60 min at 50-70 ℃, adding a film-forming assistant, a defoaming agent, a leveling agent and a wetting agent into the aqueous polyester dispersion liquid, and mixing for 30-60 min to obtain the aqueous polyester coating liquid, wherein the isocyanate index of the system after mixing is 1.05-1.1.
In a third aspect, the present invention provides a use of the aqueous polyester coating solution according to the first aspect in a protective coating layer for a polycarbonate substrate.
Compared with the prior art, the invention has the following beneficial effects:
(1) the preparation raw materials of the aqueous polyester coating liquid provided by the invention comprise aqueous polyester, a closed curing agent, a film forming aid, butanone and water, wherein the butanone is added as a pretreatment agent, the aqueous polyester containing aqueous monomers with the mole percentage content of not more than 5% is successfully dissolved or dispersed into aqueous polyester dispersion liquid by using the water, so that the content of the aqueous monomers in the aqueous polyester coating liquid is minimized under the condition of ensuring the clarity and transparency of the coating liquid, and the obtained aqueous polyester coating liquid has excellent water resistance, alkali resistance and solvent resistance after being formed into a film, and simultaneously has higher hardness, and is particularly suitable for being used as a protective coating of a polycarbonate substrate.
(2) The preparation raw materials of the water-based polyester coating liquid provided by the invention also comprise a closed curing agent which is a single-component coating liquid, the closed curing agent is introduced in the process of resin hydration, and can be directly used subsequently without adding a curing agent, and on the premise of ensuring high adhesive force between a protective coating formed after curing and a base material, the problem that flocculation is easy to occur in the coating liquid due to the influence on the balance of a water-based polyester dispersion liquid caused by the addition of the curing agent when the conventional two-component water-based polyester liquid is used is avoided.
(3) The invention further limits the types of film forming additives and structural monomers in the water-based polyester, so that the obtained water-based polyester coating liquid is clear and transparent whitish emulsion in appearance, the formed coating is free of defects, the coating hardness can reach 3H, the adhesive force with a polycarbonate substrate can reach 5B, the MEK (methyl ethyl ketone) test is more than or equal to 50 times, the alcohol resistance is more than or equal to 300 times, the boiling water resistance test coating does not fall off, the alkali resistance test coating does not corrode, and the water-based polyester coating liquid has excellent comprehensive performance.
Detailed Description
The technical solution of the present invention is further explained by the following embodiments. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitations of the present invention.
Preparation example 1
A water-based polyester, the preparation method comprises: 509.1g of dimethyl terephthalate, 221.4g of dimethyl isophthalate, 11.3g of dimethyl isophthalate-5-sodium sulfonate, 285g of polycarbonate diol (Asahi chemical synthesis, T5652), 207.8g of neopentyl glycol, 176.9g of ethylene glycol, 82.2g of 1, 4-cyclohexanedimethanol, 50ppm of tetrabutyl titanate and 40ppm of zinc acetate are put into a stainless steel reaction kettle, stirred at 100rpm under the protection of nitrogen, rapidly heated to 140 ℃ for full mixing, gradually heated to 180 ℃ for reaction for 2h, further heated to 230 ℃ for reaction for 2.5h, the reaction is ended when the esterification rate is more than 95%, finally 90ppm of triethyl phosphorylacetate and 20ppm of antimony trioxide are added, the temperature is continuously heated and slowly reduced to adjust the rotation speed to 60rpm, the temperature is controlled at 240 ℃, the pressure is gradually reduced to below 100Pa for polycondensation reaction, and the stirring is stopped when the polymer viscosity reaches 0.7dl/g, and removing the vacuum to obtain the water-based polyester.
Preparation example 2
An aqueous polyester which was different from preparation example 1 in that dimethyl terephthalate was used in an amount of 494.4g, dimethyl isophthalate-5-sulfonate was used in an amount of 33.8g, and the other components, amounts and preparation methods were the same as those of preparation example 1.
Preparation example 3
An aqueous polyester which was different from preparation example 1 in that the amount of dimethyl terephthalate was 479.6g, the amount of dimethyl isophthalate-5-sulfonate was 56.3g, and the other components, amounts and preparation methods were the same as those of preparation example 1.
Preparation example 4
An aqueous polyester which was different from preparation example 1 in that dimethyl terephthalate was used in an amount of 512.8g, dimethyl isophthalate-5-sulfonate was used in an amount of 5.64g, and the other components, amounts and preparation methods were the same as those of preparation example 1.
Preparation example 5
An aqueous polyester which was different from preparation example 1 in that polycarbonate diol was not added, neopentyl glycol was added in an amount of 237.5g, and other components, amounts and preparation methods were the same as those of preparation example 1.
Comparative preparation example 1
An aqueous polyester which was different from preparation example 1 in that dimethyl terephthalate was used in an amount of 516.5g, dimethyl isophthalate-5-sulfonate was not added, and the other components, amounts and preparation methods were the same as those of preparation example 1.
Comparative preparation example 2
A water-based polyester which is different from preparation example 1 in that the amount of dimethyl terephthalate was 516.5g, the amount of dimethyl isophthalate-5-sulfonate was 84.4g, and the amount of dimethyl isophthalate was 166g, and the other components, amounts and preparation methods were the same as those of preparation example 1.
Example 1
The water-based polyester coating liquid for the protective coating comprises the following preparation raw materials in parts by weight:
the preparation method of the aqueous polyester coating solution provided by the embodiment comprises the following steps:
(1) adding the water-based polyester (preparation example 1) and butanone into a reaction kettle, heating to 50 ℃ for mixing, after the water-based polyester is completely dissolved, gradually adding deionized water into the reaction kettle, heating to 90 ℃ at a heating rate of 1.5 ℃/min, recovering butanone condensate through a condensation reflux device, and stopping heating when the recovery rate of butanone condensate droplets is less than 1 droplet/min to obtain a water-based polyester dispersion liquid;
(2) and (2) adding an isocyanate curing agent XP2706 into the aqueous polyester dispersion liquid obtained in the step (1), mixing and stirring for 40min at 65 ℃, adding tetrahydrofuran dimethanol, a wetting agent Tego WET270, a flatting agent BYK-190 and a defoaming agent BYK-028, and continuously stirring for 50min to obtain the aqueous polyester coating liquid.
Examples 2 to 3
An aqueous polyester coating liquid for a protective coating layer is different from example 1 only in that the aqueous polyester obtained in preparation examples 2 to 3 is respectively used instead of the aqueous polyester obtained in preparation example 1, and other components, use amounts and preparation methods are the same as those of example 1.
Example 4
An aqueous polyester coating solution for protective coating differing from example 1 only in the amount of tetrahydrofuran dimethanol used of 0.75 parts by weight, the amount of deionized water used of 135.75 parts by weight, and the other components, amounts and preparation methods were the same as those of example 1.
Example 5
An aqueous polyester coating solution for protective coating differing from example 1 only in the amount of tetrahydrofuran dimethanol used of 2 parts by weight, the amount of deionized water used of 134.5 parts by weight, and the other components, amounts and preparation methods were the same as those of example 1.
Example 6
An aqueous polyester coating liquid for protective coating differing from example 1 only in that diethylene glycol monobutyl ether (boiling point 201 ℃) was used instead of tetrahydrofuran dimethanol in example 1 as a film forming aid, and the other components, amounts and preparation methods were the same as in example 1.
Example 7
An aqueous polyester coating liquid for a protective coating layer differs from example 1 only in that the aqueous polyester provided in preparation example 4 is used in place of the aqueous polyester obtained in preparation example 1, and the other components, amounts and preparation methods are the same as in example 1.
Example 8
An aqueous polyester coating liquid for a protective coating layer, which differs from example 1 only in that the aqueous polyester provided in preparation example 5 is used in place of the aqueous polyester obtained in preparation example 1, and the other components, amounts and preparation methods are the same as in example 1.
Comparative examples 1 to 2
An aqueous polyester coating liquid for a protective coating layer differs from example 1 only in that the aqueous polyester obtained in preparation examples 1 is replaced with the aqueous polyester obtained in comparative preparation examples 1 to 2, respectively, and the other components, the amounts and the preparation methods are the same as those of example 1.
Comparative example 3
An aqueous polyester coating solution for a protective coating layer was distinguished from example 1 only in that a film-forming aid was not added, deionized water was added in an amount of 136.5 parts by weight, and the other components, amounts and preparation methods were the same as in example 1.
Comparative example 4
An aqueous polyester coating liquid for protective coating which is different from the preparation raw material of example 1 in that butanone is not added and other components and amounts are the same as those of example 1;
the preparation method of the aqueous polyester coating solution provided by the comparative example includes: adding the water-based polyester (preparation example 1) and deionized water into a reaction kettle, adding an isocyanate curing agent XP2706, reacting for 40min at 60 ℃, adding tetrahydrofuran dimethanol, a wetting agent Tego WET270, a flatting agent BYK-190 and a defoaming agent BYK-028, and continuously stirring for 50min to obtain the water-based polyester coating liquid.
And (3) performance testing:
the preparation process of the protective coating comprises the following steps: selecting a proper wet film preparation device (50-200 mu m) or a wire bar (OSP 10-OSP 40#), sucking a proper amount of aqueous polyester coating liquid to be placed on a PC (polycarbonate) film in a linear shape, uniformly coating the coating from top to bottom, then placing the coating liquid into a constant-temperature air-blowing oven heated to 110-120 ℃, drying the coating liquid for 15s, taking the coating liquid out, cooling the coating liquid to room temperature, testing the thickness of the coating layer by using a spiral micrometer, controlling the thickness of the coating layer to be 3 +/-1 mu m, then performing post-curing treatment at 60-90 ℃ for 48h, and placing the coating liquid into a constant-temperature and constant-humidity environment to obtain a sample to be tested of the protective coating;
(1) appearance of the solution: visually observing the color and the state of the aqueous polyester coating liquid;
(2) coating film forming property: judging the eye sight of the meat, and observing whether the wet film has the phenomena of shrinkage cavity, shrinkage edge, vertical lines, orange peel and the like on the PC film;
(3) coating hardness: the test is carried out according to the GB/T6739-2006 standard, and the load is 1000 g;
(4) coating adhesion force: the test was performed according to GB 9286-1998 standard;
(5) organic solvent resistance (MEK, ethanol): the test is carried out according to GB/T23989-;
(6) water resistance: testing by referring to GB/T1733-93 standard, soaking in boiling water for 30min to observe whether the coating falls off;
(7) alkali resistance: the PC film coated with the water-based polyester coating was immersed in a 5% (mass fraction) NaOH aqueous solution maintained at a constant temperature of 45 ℃ and the change in state of the coating was recorded for 30 seconds.
The aqueous polyester coating solutions provided in examples 1 to 8 and comparative examples 1 to 4 were tested according to the test methods described above, and the test results are shown in table 1:
TABLE 1
As can be seen from the data in table 1: the aqueous polyester coating liquid provided by the invention has excellent water resistance, alkali resistance and solvent resistance after being formed into a film, and simultaneously has higher hardness, is particularly suitable for being used as a protective coating of a polycarbonate substrate, can further improve the water resistance and environmental protection performance of the aqueous polyester coating liquid by further limiting the type and the amount of a film forming aid and the type of a structural monomer, and can also improve the adhesion performance between the protective coating formed after the aqueous polyester coating liquid is cured and the substrate.
The specific analysis is as follows:
firstly, it can be seen from the data of examples 1 to 4 that the aqueous polyester coating liquids provided in examples 1 to 4 are all clear and transparent whitish emulsions in appearance, and the formed coatings are all defect-free, the coating hardness can reach 3H, the adhesion to the polycarbonate substrate can reach 5B, the MEK resistance test is not less than 50 times, the alcohol resistance is not less than 300 times, the boiling water resistance test coatings do not fall off, and the alkali resistance test coatings are not corroded.
Secondly, comparing example 1 with comparative examples 1 to 4, it can be found that: first, a coating solution (comparative example 1) using an aqueous polyester synthesized without adding an aqueous monomer as a film-forming substance was hardly completely dissolved, and the solution was in the form of a residue. ② the coating liquid (comparative example 2) which adopts the water-based polyester synthesized by water-based monomer with the molar content higher than 5 percent as the film-forming substance has clear and transparent appearance, but blue light, the cured coating has slight edge shrinkage, simultaneously the hardness of the coating is only 2H, and the boiling water resistance and the corrosion resistance are poor. ③ the coating obtained by not adding the film-forming assistant has serious shrinkage after curing, lower hardness, reduced adhesion with the polycarbonate substrate, and poor solvent resistance, boiling water resistance and corrosion resistance. Butanone is not added in the preparation raw materials, namely butanone is not used as pretreatment, the water-based polyester is difficult to be completely dissolved in water, and the water-based polyester coating liquid cannot be prepared at all.
Finally, a comparison of example 1 and examples 5 to 8 shows that: the addition amount of the film-forming assistant is higher than the preferable range (example 5) defined by the invention, so that the adhesion between the protective coating formed after the coating liquid is formed into a film and the polycarbonate substrate is reduced, and the corrosion resistance of the protective coating is influenced; the coating liquid (example 6) prepared by using the film-forming aid with the boiling point lower than 250 ℃ also has the problem of reduced adhesion with a polycarbonate substrate after curing, and can also cause the reduction of boiling water resistance and corrosion resistance of a protective coating; ③ the coating liquid (example 7) prepared from the aqueous polyester synthesized from the aqueous monomer with a slightly lower molar percentage had a translucent appearance, and the corrosion resistance of the protective coating formed after curing was slightly reduced; and the hardness and adhesion with the base material of the protective coating formed after the coating liquid (example 8) prepared from the aqueous polyester synthesized without using polycarbonate diol as a structural monomer is cured are low, and the solvent resistance, the boiling water resistance and the corrosion resistance are poor.
The applicant states that the present invention is illustrated by the above examples to an aqueous polyester coating solution for protective coating, a preparation method and applications thereof, but the present invention is not limited to the above examples, i.e., it does not mean that the present invention must be implemented by relying on the above examples. It should be understood by those skilled in the art that any modification of the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific modes, etc., are within the scope and disclosure of the present invention.
Claims (10)
1. The water-based polyester coating liquid for the protective coating is characterized in that the preparation raw materials of the water-based polyester coating liquid comprise water-based polyester, a closed curing agent, a film-forming aid, butanone and water;
and the mole percentage content of the water-based monomer in the synthetic monomer of the water-based polyester is not higher than 5% and is not equal to 0.
2. The aqueous polyester coating solution according to claim 1, wherein the number average molecular weight of the aqueous polyester is not less than 20000;
preferably, the synthetic monomers of the aqueous polyester include structural monomers and aqueous monomers;
preferably, the aqueous monomer comprises any one or a combination of at least two of dimethyl isophthalate-5-sodium sulfonate, isophthalic acid-5-sodium sulfonate or succinic anhydride sulfonic acid;
preferably, the mole percentage of the water-based monomer in the synthetic monomer of the water-based polyester is 0.5-5%;
preferably, the structural monomers comprise dibasic acid monomers and dihydric alcohol monomers;
preferably, the dibasic acid monomer comprises dicarboxylic acid and/or an esterified product of dicarboxylic acid;
preferably, the dicarboxylic acid comprises terephthalic acid and/or isophthalic acid;
preferably, the esterified compound of the dicarboxylic acid comprises dimethyl terephthalate and/or dimethyl isophthalate;
preferably, the diol monomer comprises any one or a combination of at least two of polycarbonate diol, neopentyl glycol, ethylene glycol or 1, 4-cyclohexanedimethanol, and is further preferably polycarbonate diol.
3. The aqueous polyester coating solution according to claim 1 or 2, wherein the blocked curing agent comprises a blocked aqueous isocyanate curing agent;
preferably, the deblocking temperature of the blocked curing agent is not lower than 80 ℃.
4. The aqueous polyester coating solution as claimed in any one of claims 1 to 3, wherein the film-forming assistant has a boiling point of not less than 250 ℃;
preferably, the mass percentage content of the film-forming aid in the aqueous polyester coating liquid is not higher than 1%;
preferably, the coalescing agent comprises any one of or a combination of at least two of triethylene glycol monobutyl ether, tetrahydrofuran dimethanol or tripropylene glycol n-butyl ether.
5. The aqueous polyester coating solution as claimed in any one of claims 1 to 4, wherein the raw materials for preparing the aqueous polyester coating solution comprise the following components in parts by weight:
6. the aqueous polyester coating solution according to any one of claims 1 to 5, wherein the raw materials for preparing the aqueous polyester coating solution further comprise any one or a combination of at least two of a leveling agent, a defoaming agent and a wetting agent.
7. A method for preparing the aqueous polyester coating solution according to any one of claims 1 to 6, comprising the steps of:
(1) mixing water-based polyester and butanone, adding water, and heating to remove the butanone to obtain a water-based polyester dispersion liquid;
(2) adding a blocked curing agent into the aqueous polyester dispersion liquid obtained in the step (1) for mixing, and then adding a film-forming aid, an optional defoaming agent, an optional leveling agent and an optional wetting agent for mixing to obtain the aqueous polyester coating liquid.
8. The method according to claim 7, wherein the mixing temperature of step (1) is not higher than 60 ℃;
preferably, the water is added in step (1) in a stepwise manner;
preferably, the temperature rise rate in the step (1) is 1-2 ℃/min;
preferably, the temperature of the system after the temperature rise in the step (1) is 90-95 ℃.
9. The preparation method according to claim 7 or 8, wherein the mixing temperature for adding the blocked curing agent for mixing in the step (2) is 50-70 ℃;
preferably, the mixing time for adding the closed curing agent to mix in the step (2) is 30-60 min;
preferably, the isocyanate index of the system after the addition and mixing of the blocked curing agent in the step (2) is 1.05-1.1;
preferably, the mixing time for mixing the film forming aid, the optional defoaming agent, the optional leveling agent and the optional wetting agent in the step (2) is 30-60 min.
10. Use of the aqueous polyester coating liquid according to any one of claims 1 to 6 as a protective coating for a polycarbonate substrate.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116445031A (en) * | 2023-04-20 | 2023-07-18 | 中科国生(杭州)科技有限公司 | Application of 2, 5-tetrahydrofuran dimethanol derivative in preparation of water-based paint |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102295779A (en) * | 2011-05-17 | 2011-12-28 | 浙江大学 | Long-chain branched polyester and preparation method thereof |
| CN108752571A (en) * | 2018-04-28 | 2018-11-06 | 华中师范大学 | It is a kind of using useless PET plastic bottle as the aqueous polyester resin for coating of primary raw material |
| CN114736351A (en) * | 2022-05-10 | 2022-07-12 | 江苏富琪森新材料有限公司 | Blocked isocyanate curing agent, preparation method thereof and baking type coating |
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- 2022-07-13 CN CN202210827216.XA patent/CN114958161A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102295779A (en) * | 2011-05-17 | 2011-12-28 | 浙江大学 | Long-chain branched polyester and preparation method thereof |
| CN108752571A (en) * | 2018-04-28 | 2018-11-06 | 华中师范大学 | It is a kind of using useless PET plastic bottle as the aqueous polyester resin for coating of primary raw material |
| CN114736351A (en) * | 2022-05-10 | 2022-07-12 | 江苏富琪森新材料有限公司 | Blocked isocyanate curing agent, preparation method thereof and baking type coating |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116445031A (en) * | 2023-04-20 | 2023-07-18 | 中科国生(杭州)科技有限公司 | Application of 2, 5-tetrahydrofuran dimethanol derivative in preparation of water-based paint |
| CN116445031B (en) * | 2023-04-20 | 2024-07-09 | 中科国生(杭州)科技有限公司 | Application of 2, 5-tetrahydrofuran dimethanol derivative in preparation of water-based paint |
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