CN114773518B - Copolymer emulsion, aqueous base material of paint and preparation method thereof - Google Patents

Abstract

The invention relates to a copolymer emulsion, an aqueous base material of paint and a preparation method thereof, wherein the copolymer emulsion is obtained by free radical aqueous emulsion polymerization of a plurality of monomers, and comprises 20-90 mass percent of one or more tertiary ethylene carbonate, 5-30 mass percent of ethylene, 5-30 mass percent of fluoroolefin, 0.1-1 mass percent of silane monomer and 0.1-1 mass percent of acrylic acid or acrylic acid substituted by saturated alkyl containing 1-4 carbon atoms at the alpha position. The copolymer emulsion is used for preparing aqueous base materials of coating, can be suitable for coating polyolefin-based base materials such as automobile parts, furniture and other formed parts, and is especially suitable for coating automobile bumpers based on polyolefin materials.

Description

Copolymer emulsion, aqueous base material of paint and preparation method thereof

Technical Field

The present invention relates to a copolymer emulsion for an aqueous base material of polyolefin coating materials, which can be suitably used for coating polyolefin-based base materials such as automobile parts, furniture and other molded parts, and is particularly suitable for coating automobile bumpers based on polyolefin materials, and a method for preparing the same.

Background

The plastic material has the advantages of low density, excellent heat resistance and weather resistance, good impact resistance and good formability, is widely applied to industries such as household appliances, automobiles, building materials, office equipment, electronic communication, medical appliances and the like, and is an important material indispensable for national economy and national defense construction.

Particularly in the automobile industry, polypropylene (PP) and modified polypropylene materials are used in all plastic varieties, which account for more than 30% of plastics for automobiles, and PP materials can be used for parts such as bumpers, dashboards, glove boxes, door shields, auxiliary dashboards, pillar shields, seat shields and the like of automobiles.

However, plastics are not ideal in terms of resistance to environmental corrosion such as ultraviolet light, and various surface defects are often generated after processing and molding. Therefore, the application of the plastic is necessary to carry out secondary processing, namely coating is carried out by using the paint, thereby achieving the decorative effect, improving the corrosion resistance and the weather resistance and prolonging the service life.

Compared with other low-pollution coatings, the water-based coating is a preferred variety because the water-based coating has the characteristics of multiple technical paths, wide application range, safety, relatively simple construction and the like, so the development and application of the environment-friendly water-based plastic coating are the main stream of development.

At present, the water-based paint varieties applicable to plastic products in the market mainly comprise water-soluble paint and emulsion paint. According to the resin classification, there are mainly aqueous acrylic acid, aqueous one-component polyurethane, aqueous two-component polyurethane, etc., and further include aqueous photo-curing type. These varieties are mainly applied to the surfaces of non-crystalline and polar plastics such as ABS, PS, PC/ABS, PVC and the like.

For nonpolar PE, PP and other crystalline plastics with very small surface tension, development of water-based paint has great difficulty, and the problem of weak adhesive force is common. One of the current solutions is to subject such substrates to a specific pre-surface treatment, such as corona discharge or flame treatment, to increase the adhesion of the substrate to the coating. However, these methods have complicated steps, uneven surface treatment effect, short activation time, high cost, and high risk, and have great drawbacks.

If the substrate is directly coated without pretreatment, the following two modes can be adopted:

first, efforts are made to "break" the microcrystalline regions of the plastic surface to improve wettability. For example, in aqueous coatings, certain amounts of co-solvents are used to reduce the surface tension of the coating system and to swell the substrate surface, allowing resin molecules to penetrate the substrate surface layer during drying to improve adhesion. The method damages the plastic surface, and the environmental protection advantage of the water-based paint is counteracted due to the use of a large amount of solvent.

Second, efforts have been made to "extend" the domain structure to increase the inter-resin compatibility, i.e., to obtain satisfactory adhesion using a functional resin having a similar structure to the surface of the plastic substrate as an additive component. The typical method is to make the chlorinated polypropylene resin water-based by external emulsification or other modification methods, such as graft modification of chlorinated polyolefin or addition of an appropriate amount of chlorinated polyolefin in a conventional copolymerization emulsion reaction to obtain both adhesion and functional groups. Several patent documents describe the same and similar methods as: EP1364977-A1, JP2006104432, US5777022, US5349022, US6344500, EP0466743, GB2254082-A, EP1354923, US5693423-A, US20030162887, CN201010102117.2, CN200710010657.6, CN201811038727.3, CN201811039290.5, CN201910466532.7 and CN202110914140.X and the like.

The second mode has the defect that the chlorinated polyolefin is hydrophobic resin, hydrophilic groups are added to the chlorinated polyolefin to be the water-based resin, the hydrophilic groups are difficult to hydrate when the addition amount is insufficient, and the water resistance of the resin and the final coating is obviously reduced when the addition amount is insufficient. Meanwhile, the aqueous resin has poor compatibility with other aqueous resins, and is difficult to use together. In summary, this method must achieve a certain beneficial and delicate balance, which requires very complex processes, precise operations and special raw materials, which makes it difficult to realize large-scale industrialization.

It can be seen that the future development of aqueous coating binders in the field of crystalline polyolefin materials represented by PP materials is limited to the aqueous modification of chlorinated polypropylene resins, and thus new breakthroughs are needed.

Disclosure of Invention

The invention aims to provide a copolymer emulsion which can be used for an aqueous base stock of polyolefin coating. The copolymer in the base material does not depend on chlorinated polyolefin materials, has low VOC and high solid content, can be dried or solidified into a film at a low temperature, has excellent adhesive force on crystalline polyolefin substrates represented by polypropylene, can bond polyolefin substrates without surface treatment, has good compatibility with other water-based resins, and is used cooperatively.

The invention also aims to provide the aqueous base material and a preparation method thereof.

Through extensive research and experimentation, the present inventors have unexpectedly discovered a copolymer emulsion obtained by free radical aqueous emulsion polymerization of the following comonomers:

monomer (1) 20-90 mass% of one or more vinyl versatates;

monomers (2)5-30 mass% ethylene;

monomers (3)5-30 mass% of fluoroolefins;

monomer (4) 0.1 to 1 mass% silane monomer;

monomer (5) 0.1 to 1 mass% of acrylic acid or saturated alkyl-substituted acrylic acid having 1 to 4 carbon atoms in the alpha position; and

monomers (6)0-20 mass% of equimolar adducts of a glycidyl versatate and an acrylic acid substituted with a saturated alkyl group containing 1-4 carbon atoms in the alpha position).

In some embodiments, the comonomer (1) is preferably vinyl versatate having 9 or 10 carbon atoms in an amount of 30 to 90% by weight of the total monomer mass.

In some embodiments, comonomer (3) is preferably tetrafluoroethylene or chlorotrifluoroethylene, alternatively.

In some embodiments, the silane monomer in comonomer (4) has the following structure:

(R1)(R2)(R3)Si-R

wherein R1, R2 and R3 represent identical or different alkoxy groups, preferably hydrolyzable alkoxy groups having 1 to 4 carbon atoms, and R represents an ethylenically unsaturated olefin group. Preference is given to methacryloxyalkyl trialkoxysilanes and vinyl trialkoxysilanes in which the alkyl and alkoxy groups contain from 1 to 4 carbon atoms. More preferred are methacryloxypropyl trimethoxysilane and vinyl triisopropoxysilane.

In some embodiments, comonomer (5) preferably comprises from 0.1% to 0.7% acrylic acid by total mass of monomer.

In some embodiments, the equimolar adduct of the comonomer (6) glycidyl versatate and methacrylic acid comprises from 0 to 20%, preferably from 0 to 10%, more preferably from 0 to 7%, most preferably from 0 to 4% of the total mass of the monomers. The term "equimolar adduct of glycidyl versatate and methacrylic acid" as used in the present invention refers to a molar ratio between glycidyl versatate and (meth) acrylic acid ranging from 0.95:1 to 1.05:1, preferably as close to 1:1 as possible.

In some embodiments, the emulsion polymerization of the present invention incorporates at least one surfactant having a critical micelle mass concentration of less than 0.05% as an emulsifier, which is a wide variety of options, preferably sodium ditridecylsulfosuccinate.

The inventors found that the above copolymer emulsion is excellent in performance when used for preparing an aqueous base material of a coating.

In some embodiments, the aqueous base of the present invention contains a wetting agent. Preferably, the wetting agent is a surfactant which is capable of achieving a surface tension of less than 25 dynes in the aqueous solution at a concentration of 1000m by mass. Such wetting agents include a wide variety of types, preferably those suitable for use in coatings. In particular, the wetting agent is preferably a silicone wetting agent, such as, for example, a dakaning DC67. Preferably 1-4% by mass of aqueous solution, in an amount of 2-3% by mass of the total emulsion.

In some embodiments, when monomer (6) is included in the aqueous base copolymer of the present invention, it is preferable to add polyisocyanate or its derivative as an external crosslinking agent if necessary due to the hydroxyl group being introduced. The crosslinking agent used should have 2 or more reactive isocyanate groups per molecule, preferably 3, and have a polar structure. Among such polyisocyanates, preferred are cycloaliphatic polyisocyanates, more preferred are hydrophilically modified aliphatic polyisocyanates based on isophorone diisocyanate (IPDI). The amount of the cross-linking agent is as follows: from 0.5 to 3 isocyanate groups, preferably from 0.8 to 2, more preferably from 1 to 1.5, are required per hydroxyl group on the polymer.

Unexpectedly, the aqueous base of the present invention exhibits surprising adhesion after film formation on an untreated polypropylene substrate, with a surface tension of only 30 dynes, which meets the polypropylene materials 30-34 dynes required by the automotive industry.

The aqueous binder coating of the present invention may be applied to polyolefin substrates, particularly polypropylene substrates, which have not been subjected to flame or corona discharge surface treatment. After drying or curing to form a film, one or more layers of coating can be further coated on the surface of the film, and the film has excellent compatibility with other resins.

In addition, the aqueous base stock of the invention can also be applied to sizing agents for polypropylene reinforced fibers, in particular glass fibers.

The copolymer emulsion in the aqueous binder of the invention can be prepared by methods known to the person skilled in the art, namely: the monomers (1) to (5) or (1) to (6) are dispersed in an aqueous medium by emulsifying with an emulsifier, initiated with an initiator and prepared by free radical polymerization. Batch, semi-continuous, seed emulsion polymerization, etc. may be employed.

Preferably, in some embodiments, the emulsifiers useful in the emulsion polymerization of the present invention include anionic emulsifiers, nonionic emulsifiers, or a combination of both. Since the monomers used in the present invention all have a relatively strong low surface tension property, at least one low surface tension surfactant is required. By "low surface tension surfactant" is meant any surfactant having a critical micelle concentration of less than 0.05 mass%. Anionic surfactants suitable for use in the present invention are, for example: diester sulfosuccinates, monoester sulfosuccinates, sulfosuccinamates, nonylphenol ether sulfates, and alkylaryl polyether sulfonates sodium salts, fatty alcohol ether sulfates, alkylphenol ether sulfates, and low CMC phosphate surfactants, such as aliphatic phosphate esters containing 3, 6, and 10 moles of ethylene oxide. Suitable nonionic surfactants include: alkylaryl polyether alcohols, alkylphenol ethoxylates, fatty alcohol ethoxylates, fatty acid esters, and the like. A preferred low surface tension surfactant is sodium ditridecylsulfonate.

In some embodiments, the present invention may also use reactive surfactants. By "reactive surfactant" is meant a compound with at least one unsaturated double bond for free radical polymerization with monomers and monomer mixtures, while also containing a low surface tension and hydrophilic moiety similar to conventional surfactants to maintain surface activity. Surfactant monomers include long chain alkoxy-or alkylphenoxy-polyalkylene oxide (meth) acrylates, e.g. C ₁₈ H ₂₇ - (ethylene oxide) ₂₀ Methacrylic acid esters and C ₁₂ H ₂₅ - (ethylene oxide) ₂₃ Methacrylates and the like.

The low surface tension surfactant in the present invention is added in an amount effective to enhance the polymerization of the monomer mixture containing the low surface tension monomer under emulsion polymerization conditions. In some embodiments, the low surface tension surfactant is preferably present in the polymerization mixture in an amount of from 0.01% to 5% by weight of the total mass of the monomers, more preferably from 0.05% to 3% by weight of the total mass of the monomers, and most preferably from 0.1% to 1.5% by weight of the total mass of the monomers. In addition to the low surface tension surfactant, other surfactants may be present during the polymerization in an amount of 0% to 5% of the total mass of the monomers, preferably 0% to 3% of the total mass of the monomers, more preferably 0% to 1.5% of the total mass of the monomers. The mass percentages of these surfactants are based on the mass of dry surfactant (i.e., surfactant without water).

In carrying out the emulsion polymerization, the initiator is preferably used in a concentration sufficient to initiate the polymerization. In some embodiments, the initiator is added in an amount of about 0.01% to about 3%, preferably about 0.05% to 2%, and most preferably about 0.1% to about 1% of the total mass of monomer added. As is well known to those skilled in the art, the particular concentration used will depend on the particular monomer mixture being reacted and the particular initiator being used, including hydrogen peroxide, peracetic acid, t-butyl hydroperoxide, di-t-butyl hydroperoxide, dibenzoyl peroxide, peroxybenzoic acid, 2, 4-dichlorobenzoyl peroxide, 2, 5-dimethyl-2, 5-bis (hydroperoxy) hexane, perbenzoic acid, t-butyl peroxypivalate, t-butyl peracetate, dilauroyl peroxide, dioctyl peroxide, distearoyl peroxide, dibenzoyl peroxide, diisopropyl peroxydicarbonate, didecyl peroxydicarbonate, biseicosyl peroxydicarbonate, di-t-butyl perbenzoate, 2' -even di-2, 4-dimethylvaleronitrile, ammonium persulfate, potassium persulfate, sodium persulfate, and azobisisobutyronitrile, as well as any other known initiator. Preferably, redox initiator systems such as sodium persulfate-sodium formaldehyde sulfoxylate, t-butyl hydroperoxide-sodium metabisulfite, hydrogen peroxide-ascorbic acid, and other known redox systems may also be used. In addition, as known to those skilled in the art, trace amounts of certain metal ions may be added as activators to improve the polymerization rate, if desired.

To ensure the pH of the system, an alkaline buffer may be added. The addition amount is 0.1-0.5% of the total mass of the monomers, so as to adjust the pH of the system to a desired value. Alkaline buffers include sodium acetate, ammonium bicarbonate, sodium bicarbonate, and disodium phosphate and the like.

The emulsion polymerization of the present invention is carried out at a temperature of 40-90℃and lower polymerization temperatures increase the average molecular weight of the copolymer. The reaction temperature can be controlled by controlling the rate of addition of initiator, as well as the rate of heat exchange. Preferably, the polymerization temperature of the present invention is 70℃on average.

The polymerization time of the present invention is 3 to 10 hours, which can be determined according to the temperature, the amount of initiator and the desired polymerization conversion, and usually the polymerization can be completed by reacting for 6 hours. The end point of the reaction is desirably less than 0.5% without significant exotherm and residual monomer.

In the polymerization of the present invention, taking fluoroolefin as an example of tetrafluoroethylene, ethylene monomer and tetrafluoroethylene as gaseous monomers, the amount of copolymerization produced is dependent on a variety of factors, including: the concentration and type of the emulsifier, the reaction pressure, the stirring speed and the viscosity of the reaction liquid in the polymerization process. In order to increase the ethylene and polytetrafluoroethylene content of the copolymer, higher reaction pressures may be used. However, even if the amount of ethylene monomer in the copolymer is to be 30%, it is not necessary to exceed a pressure of 12MPa, and the minimum reaction pressure is more than 2.5MPa. Similarly, when the fluoroolefin is chlorotrifluoroethylene, the reaction pressure should be 2.5-12MPa. In addition, in order to obtain higher ethylene and polytetrafluoroethylene contents in the copolymer, the stirring speed can be increased and the viscosity of the reaction medium can be reduced, the reaction medium viscosity preferably being less than 1000 mpa.s.

The emulsion polymerization process of the invention: firstly, preparing an aqueous solution containing an emulsifier, a PH regulator and the like, adding the aqueous solution and a monomer (including the monomer (3) which is trifluorochloroethylene) to be added in the initial stage into a polymerization kettle, then introducing ethylene or a mixed gas of ethylene and tetrafluoroethylene (when the monomer (3) is tetrafluoroethylene, the mixed gas of ethylene and tetrafluoroethylene is adopted) into the polymerization kettle to a set pressure, starting stirring to fully stir, and generally taking 15 minutes to achieve a sufficient mass transfer balance. If the stirring efficiency is high or the reaction system is special, the time can be shortened. At the same time, the temperature of the reaction medium is raised to the set reaction temperature. The polymerization was started by continuing the addition of the initial amount of initiator. After the polymerization reaction starts, an initiator, a tertiary ethylene monomer and chlorotrifluoroethylene (if not all of them are added to the starting material) are continuously added according to the progress of the polymerization reaction, and the reaction is carried out at a certain constant polymerization pressure by adjusting the addition amount of ethylene or a mixed gas of ethylene and tetrafluoroethylene. After the whole reaction materials are added, the temperature needs to be kept for a period of time so as to enable the polymerization reaction to be more thoroughly carried out. The post initiator is then added at this temperature to effect post initiation to further reduce the residual monomer content.

The polymerization reaction is finished when the residual monomer content is lower than 0.5%, the temperature of the polymerized product is reduced to room temperature, and the pH value of the polymerized product is adjusted to be 4.5-7, preferably 6-6.5 by neutralization and then the polymerized product is discharged.

The copolymer emulsion obtained above is mixed with a wetting agent, and in some implementations, with isocyanate or its derivatives as desired, to make the aqueous base of the present invention.

In some embodiments, the aqueous base of the present invention is also formulated into a coating by adding one or more additional ingredients including, but not limited to, curing accelerators such as dibutyltin dilaurate, pigments, pearlescent flakes, including electrically conductive fillers, plasticizers, antioxidants, surfactants, and flow control agents.

The aqueous base material or the coating prepared by the aqueous base material can be applied by adopting conventional processes such as spraying, electrostatic spraying, dipping, brushing, pouring coating, roller coating and the like. Among these, spray coating or roll coating is the preferred process.

Compared with the prior art, the invention has the following advantages and beneficial effects:

(1) The aqueous binder of the present invention is free of chlorinated olefin resins such as chlorinated polypropylene. But fully utilizes the low surface tension characteristic of the copolymer of vinyl versatate, ethylene and fluoroolefin to carry out formulation design and repeated experiments, and the unexpectedly obtained aqueous base material of the novel polyolefin coating is completely different from the existing chlorinated olefin resin aqueous process.

(2) The aqueous base material has excellent adhesive force to polyolefin, especially polypropylene material, and the substrate does not need to be subjected to flame or corona discharge and other surface treatments when the polyolefin surface is coated, so that a great deal of cost is saved.

(3) The aqueous base material is suitable for coating molded articles such as automobile polypropylene bumpers.

(4) The aqueous base material of the invention can be further coated with one or more layers of other types of coatings after being coated on the surface of polyolefin for drying or curing to form a film. Namely, the primer layer can be firmly adhered to polyolefin on one hand, and has excellent compatibility with other types of coatings on the other hand, and is tightly combined with the polyolefin to play a role in bridging the coatings.

(5) One significant advantage of the aqueous binders of the present invention is that they dry/cure at lower temperatures, up to 80 ℃ is required, better than previously applied 120 ℃ drying/curing temperatures.

(6) Another use of the aqueous binder of the present invention is for fiber sizing of polypropylene and other thermoplastics, particularly glass fibers.

(7) The aqueous binders of the present invention may also be stored and supplied in a two-component manner. The polymer emulsion containing the monomer (6) and the polar polyisocyanate curing agent are supplied in groups, and the two are mixed together for use in coating.

Detailed Description

The following examples are given to illustrate the technical aspects of the present invention, and the scope of the present invention is not limited to these embodiments. In the interest of brevity, not all of the possible combinations of features of each embodiment or example are described. Accordingly, as long as there is no contradiction between the combinations of these technical features, any combination of the technical features in the respective embodiments or examples is possible, and all possible combinations should be considered as being within the scope of the present specification.

The vinyl versatate used in the examples of the present invention is commercially available vinyl neononanoate from Hebei four friends excellent science and technology Co., ltdAnd vinyl neodecanoate->The equimolar addition product of the tertiary glycidyl ester and the (methyl) acrylic acid is commercially available equimolar addition product of vinyl neodecanoate and methacrylic acid>And equimolar adduct of vinyl neodecanoate and acrylic acid +>The surfactant used in the examples of the present invention was disodium succinate half ester ethoxylated alcohol, such as commercially available Aerosol A-102.

The formulation of the examples is shown below, with percentages being by mass, unless otherwise indicated, in grams.

The preparation method of the copolymer emulsion comprises the following steps:

the monomers and materials in the monomer mixture were transferred into a mixing vessel according to the above example formulation table, and stirring and mixing were started to prepare a monomer mixture.

After displacement with nitrogen, the materials under the initial feed entry were added to a stainless steel autoclave equipped with a variable speed stainless steel disk turbine high speed stirrer according to the example formulation table and stirred well. Into which the initial monomers are charged. The temperature required for polymerization is obtained by adjusting the temperature set point of the thermostatic water bath. Ethylene or ethylene/tetrafluoroethylene mixtures were added to the desired pressure at a reactor temperature of 50 ℃. After addition of ethylene or ethylene/tetrafluoroethylene mixtures, the reactor contents were thoroughly mixed at 300rpm for 15 minutes.

An initial initiator-oxidant is added to the reaction vessel followed by an initial initiator-reductant. The stirrer was continuously operated at 300rpm for the duration of the initiation, after which the speed was increased to 600rpm. The reactor temperature and total pressure were increased due to the exotherm caused by the polymerization of the initial charge, and the cooling water flow rate was adjusted to control the temperature at 70 ℃.

After the heat release, each of the feed valves into the reaction vessel was opened, the remaining monomer and polymerization initiator were added dropwise thereto over a period of 3 hours, and the feed amount of ethylene or ethylene/tetrafluoroethylene mixture was controlled to control the pressure of the reaction vessel below the pressure required for polymerization.

When all feeds were complete, the contents of the reactor were allowed to react further for 60 minutes at 70 ℃ to promote residual monomer reduction.

Followed by a post-initiation, maintained at 70 ℃, and a post-initiator was added over 60 minutes to ensure that the residual monomer content was less than 0.5% of the emulsion.

After the post-initiation is completed, the reaction kettle is cooled to be lower than 30 ℃, and the product is pressed out of the reaction kettle, and is degassed and defoamed to obtain the copolymer emulsion.

Example 1

The reaction was carried out in an autoclave having a capacity of 2 liters and a pressure resistance of 20 MPa. The polymerization pressure is 3MPa, the vinyl versatate is high in reference amount, the ethylene and tetrafluoroethylene are low in reference amount, and the glass transition temperature is high. The product is ethylene neodecanoate-ethylene neononanoate-ethylene-tetrafluoroethylene tetrapolymer.

The physical properties of the ethylene neodecanoate-ethylene neononanoate-tetrafluoroethylene copolymer are as follows:

solid content	45.1％
		Glass transition temperature	35
PH	3.0
		Particle size (micron)	0.12
Viscosity (mPa. S)	52

Example 2

The reaction was carried out in an autoclave having a capacity of 2 liters and a pressure resistance of 20 MPa. The polymerization pressure is 6MPa, the incorporation of vinyl versatate, ethylene and tetrafluoroethylene is moderate, and the vitrification temperature is moderate. The product is ethylene neodecanoate-ethylene neononanoate-ethylene-tetrafluoroethylene copolymer.

The physical properties of the ethylene neodecanoate-ethylene neononanoate-tetrafluoroethylene copolymer are as follows:

solid content	45％
		Glass transition temperature	-1
PH	3.9
		Particle size (micron)	0.19
Viscosity (mPa. S)	51

Example 3

The reaction was carried out in an autoclave having a capacity of 2 liters and a pressure resistance of 20 MPa. The polymerization pressure is 10MPa, the incorporation of vinyl versatate is low, the incorporation of ethylene and tetrafluoroethylene is high, and the glass transition temperature is low. At the time of polymerizationThe monomer is added to carry hydroxyl, and the product is ethylene-tetrafluoroethylene terpolymer of neodecanoic acid.

The physical properties of the ethylene-tetrafluoroethylene terpolymer neodecanoate are as follows:

solid content	46％
		Glass transition temperature	-38
PH	3.8
		Particle size (micron)	0.17
Viscosity (mPa. S)	39

Example 4

The reaction was carried out in an autoclave having a capacity of 2 liters and a pressure resistance of 20 MPa. The polymerization pressure is 6MPa, the ethylene addition amount is low, the tetrafluoroethylene addition amount is high, and the glass transition temperature is moderate. The product is ethylene-tetrafluoroethylene terpolymer neodecanoate.

The physical properties of the ethylene-tetrafluoroethylene terpolymer neodecanoate are as follows:

solid content	45.2％
		Glass transition temperature	14
PH	3.9
		Particle size (micron)	0.18
Viscosity (mPa. S)	52

Example 5

The reaction was carried out in an autoclave having a capacity of 2 liters and a pressure resistance of 20 MPa. The polymerization pressure is 3MPa, the vinyl versatate is high in dosage, the ethylene and the chlorotrifluoroethylene are low in dosage, and the glass transition temperature is high. The product is ethylene neodecanoate-ethylene neononanoate-ethylene-chlorotrifluoroethylene tetrapolymer.

The physical properties of the ethylene neodecanoate-ethylene neononanoate-ethylene chlorotrifluoroethylene copolymer are as follows:

solid content	45％
		Glass transition temperature	37
PH	3.4
		Particle size (micron)	0.15
Viscosity (mPa. S)	46

Example 6

The reaction was carried out in an autoclave having a capacity of 2 liters and a pressure resistance of 20 MPa. The polymerization pressure is 6MPa, the vinyl versatate, the ethylene and the chlorotrifluoroethylene are moderately involved, and the glass transition temperature is moderate. The product is ethylene neodecanoate-ethylene neononanoate-ethylene-chlorotrifluoroethylene tetrapolymer.

The physical properties of the ethylene neodecanoate-ethylene neononanoate-ethylene chlorotrifluoroethylene copolymer are as follows:

solid content	44.9％
		Glass transition temperature	0
PH	3.6
		Particle size (micron)	0.15
Viscosity (mPa. S)	33

Example 7

The reaction was carried out in an autoclave having a capacity of 2 liters and a pressure resistance of 20 MPa. The polymerization pressure is 10MPa, the incorporation of vinyl versatate is low, the incorporation of ethylene and chlorotrifluoroethylene is high, and the glass transition temperature is low. The product is ethylene neodecanoate-ethylene neononanoate-ethylene-chlorotrifluoroethylene tetrapolymer.

The physical properties of the ethylene neodecanoate-ethylene neononanoate-ethylene chlorotrifluoroethylene copolymer are as follows:

solid content	45.2％
		Glass transition temperature	-34
PH	3.7
		Particle size (micron)	0.13
Viscosity (mPa. S)	40

Example 8

The reaction was carried out in an autoclave having a capacity of 2 liters and a pressure resistance of 20 MPa. The polymerization pressure is 3MPa, the ethylene addition amount is low, the chlorotrifluoroethylene addition amount is high, and the glass transition temperature is moderate. At the time of polymerizationThe monomer is added to carry hydroxyl, and the product is the vinyl neodecanoate-ethylene-chlorotrifluoroethylene terpolymer.

The physical properties of the vinyl neodecanoate-ethylene-chlorotrifluoroethylene terpolymer are as follows:

solid content	46％
		Glass transition temperature	1
PH	3.5
		Particle size (micron)	0.19
Viscosity (mPa. S)	55

Example 9

The reaction was carried out in an autoclave having a capacity of 100 liters and a pressure resistance of 10MPa, and was used for pilot scale-up experiments. The polymerization pressure is 3MPa, the ethylene addition amount is low, the chlorotrifluoroethylene addition amount is high, and the glass transition temperature is moderate. At the time of polymerizationThe monomer is added to carry hydroxyl, and the product is the vinyl neodecanoate-ethylene-chlorotrifluoroethylene terpolymer.

The physical properties of the vinyl neodecanoate-ethylene-chlorotrifluoroethylene terpolymer are as follows:

solid content	45.7％
		Glass transition temperature	1
PH	3.7
		Particle size (micron)	0.20
Viscosity (mPa. S)	60

Product detection method and result of aqueous base stock

The dry and wet adhesion test for polypropylene substrates, including single and composite coatings, was identified for aqueous binders comprising the emulsions of examples 1-9 according to the method of GB/T9286-1998 cross-hatch test for color and varnish films.

The method for preparing the single-layer coating plate comprises the following steps:

(1) Neutralizing the prepared emulsion to neutrality, adding wetting agent and solidifying agent according to the formula table of the embodiment, and stirring uniformly;

(2) Spraying the prepared emulsion on a PP test board which is not pretreated but is subjected to grease removal, standing for 30 minutes at room temperature, and then drying for 30 minutes at 80 ℃;

(3) Cooling to room temperature for testing.

The method for manufacturing the composite coating plate comprises the following steps:

(1) Neutralizing the prepared emulsion to neutrality, adding wetting agent and solidifying agent according to the formula table of the embodiment, and stirring uniformly;

(2) Spraying the prepared emulsion on a PP test board which is not pretreated but is subjected to grease removal (primer spraying), standing for 30 minutes at room temperature, and then drying for 30 minutes at 80 ℃;

(3) Coating a finishing paint on the test panel, and standing for 30 minutes at room temperature;

(4) Coating a layer of two-component varnish (finish paint spraying) on the surface of the coated finish paint, and then drying for 30 minutes at 80 ℃;

(5) Cooling to room temperature for testing.

The finish paint and the finish varnish of the composite coating are paint.

Wet adhesion was tested after 10 days of immersion in 40 ℃ water.

The test results were as follows:

the aqueous base stock of examples 3, 8 and 9 each incorporates an isocyanate curing agent, and the test results show that: all the templates have the dry and wet adhesion reaching the zero level of GB/T9286-1998 through measurement, and have very good adhesion.

The aqueous base material in the above example is coated on an untreated polypropylene substrate to form a film, and the surface tension is 30 dyne and the performance is excellent after test.

Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and are not limiting; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the previous embodiments can be modified, or the preparation reaction conditions can be replaced, or part of the technical features can be replaced equivalently; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims (16)

1. Aqueous binder for coatings, characterized in that it is made of a copolymer emulsion obtained by free-radical aqueous emulsion polymerization of the following comonomers:

20 to 90 mass% of one or more vinyl versatates of the monomer (1),

5 to 30 mass% of ethylene as monomer (2),

5 to 30 mass% of a fluoroolefin as monomer (3),

0.1 to 1 mass% of a silane monomer,

monomer (5) 0.1 to 1% by mass of acrylic acid or an acrylic acid substituted with a saturated alkyl group having 1 to 4 carbon atoms in the alpha position, and

4 to 20 mass% of an equimolar adduct of a glycidyl versatate and an acrylic acid substituted with a saturated alkyl group containing 1 to 4 carbon atoms in the alpha position of the monomer (6);

the mass sum of the monomers is 100%;

adding polyisocyanate or a derivative thereof with a polar structure as an external crosslinking agent, wherein the copolymer emulsion of the monomers (1) - (6) and the polyisocyanate or the derivative thereof form a two-component system;

at least one surfactant with critical micelle mass concentration lower than 0.05% is added as an emulsifier or a reactive surfactant is added during emulsion polymerization;

and a wetting agent which is a surfactant capable of making the surface tension of the aqueous solution below 25 dynes at a mass concentration of 1000 ppm.

2. The aqueous binder of the coating according to claim 1, wherein the monomer (1) is vinyl versatate containing 9 or 10 carbon atoms in an amount of 30 to 90% by weight based on the total mass of the monomer.

3. The aqueous binder of the coating according to claim 2, wherein the monomer (3) is tetrafluoroethylene or chlorotrifluoroethylene.

4. A waterborne binder for a coating according to claim 3, wherein the monomer (4) has the structure: (R1) (R2) (R3) Si-R

Wherein R1, R2 and R3 represent the same or different alkoxy groups, a hydrolyzable alkoxy group having 1 to 4 carbon atoms, and R represents an ethylenically unsaturated olefin group.

5. The aqueous binder of the coating material according to claim 4, wherein the monomer (5) is acrylic acid accounting for 0.1 to 0.7 percent of the total mass of the monomer.

6. The aqueous binder of any one of claims 1-5 wherein the emulsifier is sodium ditridecylsulfosuccinate.

7. The aqueous binder of claim 6 wherein the polyisocyanate or derivative thereof has at least 2 reactive isocyanate groups per molecule in an amount of 0.5 to 3 isocyanate groups per hydroxyl group on the polymer.

8. The aqueous binder of claim 7 wherein the polyisocyanate or derivative thereof is a cycloaliphatic polyisocyanate.

9. The aqueous binder of claim 8 wherein the polyisocyanate or derivative thereof is a hydrophilically modified aliphatic polyisocyanate based on isophorone diisocyanate.

10. The aqueous binder of claim 9 wherein the polyisocyanate or derivative thereof is used in an amount of: from 0.8 to 2 isocyanate groups are required for each hydroxyl group on the polymer.

11. The aqueous binder of claim 10 wherein the polyisocyanate or derivative thereof is used in an amount of: 1 to 1.5 hydroxyl groups per polymer are required.

12. The aqueous binder of claim 1 wherein the copolymer emulsion is mixed with a wetting agent at an emulsion polymerization pressure of 2.5-12MPa and a reaction temperature of 40-90 ℃.

13. The aqueous binder of claim 12 wherein the reaction temperature is 70 ℃.

14. A method of using an aqueous base stock of a coating, characterized in that the aqueous base stock of a coating according to any one of claims 1-13 is dried or cured to form a film on the surface of the coated material, and that it is used as a primer layer on the surface of which one or more further layers of coating of other types are applied.

15. Use of an aqueous binder of the coating according to any one of claims 1 to 13 for the preparation of a fiber sizing agent for polyolefin coatings or thermoplastics; or to coat polyolefin substrates that have not been flame treated or surface treated with corona discharge.

16. Use of an aqueous binder of the coating of any one of claims 1 to 13 for the preparation of a sizing agent for glass fibers; or to coat polypropylene substrates that have not been flame treated or surface treated with corona discharge; or to be applied to coating untreated shaped articles based on polypropylene materials.