JPH0656944A - Aqueous fluororesin dispersion and its production and application - Google Patents

Abstract

PURPOSE:To obtain an aqueous resin dispersion which allows good pigment dispersion and has good adherence to a base material without detriment to the weatherability. CONSTITUTION:A process for the radical emulsion polymerization of a core-shell fluororesin having a structure wherein the inner part of the particle comprises a resin composed essentially of a fluorine-free monomer and the shell of the particle comprises a resin composed essentially of a monomer having at least one chlorine atom in the molecule in an aqueous medium in the presence of an emulsifier, which comprises the first step of polymerizing a monomer mixture consisting essentially of the fluorine-free monomer to give an aqueous dispersion of the fluorine-free resin and the second step of polymerizing a monomer mixture consisting essentially of the fluorinated monomer in the presence of this fluorine-free resin.

Description

Detailed Description of the Invention

[0001]

INDUSTRIAL APPLICABILITY The present invention is novel and useful,
TECHNICAL FIELD The present invention relates to an aqueous dispersion of a fluororesin, a method for producing the same, and its application. More specifically, the present invention provides a core-shell type fluororesin aqueous dispersion (fluoroolefin copolymer emulsion) obtained by using fluorine atom-containing monomers (fluoroolefin monomers) as an essential component. ) And its production method and its application, the use of fluorine atom-containing monomers (fluoroolefin-based monomers) as the minimum essential monomers, and particularly suitable for coating. The present invention relates to a core-shell type polymer emulsion to be obtained, a method for producing the same and applications thereof.

[0002]

2. Description of the Related Art In the field of exterior covering materials,
There is a great demand for a highly practical coating material that is neither deteriorated nor discolored over a long period of time. Particularly in the field of civil engineering and construction, the surface of a so-called alkaline inorganic hardened material such as a concrete skeleton, a wall material or a roofing material is coated. , To impart water resistance and weather resistance.

Among these coating materials, those based on water-based organic polymers such as acrylic copolymers and acrylic-styrene copolymers are widely used because the coating treatment is simple.

However, in particular, when it is used as a building exterior material, it is required to have a life of at least 10 years or more, and further, a semi-permanent one. Therefore, an acrylic copolymer or acrylic-styrene is required. When an aqueous polymer such as a system copolymer is used for the top coat, it cannot be said that the weather resistance is sufficient, and as a result, recoating is required within a short period of time.

On the other hand, the fluoroolefin copolymer is known as a binder which provides high weather resistance and high chemical resistance, and an organic solvent solution is already on the market.

However, since the commercially available binder contains an organic solvent, it is problematic in terms of fire risk, toxicity and air pollution, and an aqueous type binder is required.

On the other hand, tetrafluoroethylene,
Although use of an aqueous dispersion of polymers (fluoroolefin polymers) such as vinylidene fluoride or hexafluoropropylene has been proposed, all of these polymers require baking at high temperature. , Is.

By the way, Japanese Patent Application Laid-Open No. 57-38845 discloses a copolymer of vinylidene fluoride and hexafluoropropylene. The copolymer has an intrinsic viscosity [η] of 0. Despite its low molecular weight of 0.1 to 0.5, it still requires baking at a high temperature of 180 to 230 ° C.

Therefore, even in the case of architectural paints that require a coating film to be formed at room temperature and factory paints that rely on forced drying, the high temperature baking described above is not practically practical. It is possible and not suitable for such applications.

Moreover, since the fluoroolefin type monomers are expensive, the copolymer is
It is economically disadvantageous to use only the fluoroolefin-based monomers.

By the way, JP-A-61-261367 discloses a method of solving various problems as described above, which comprises fluoroolefin, alkyl vinyl ether, and carboxylic acid vinyl ester.
Emulsion copolymer-based resin compositions for coatings have been disclosed, and it can be said that they can be applied to the exterior coating material for the time being. Insufficient in terms of dispersibility and stain resistance.

As described above, as long as the conventional technique is followed, the aqueous coating composition containing a highly durable fluoroolefin unit as a main component contains a relatively large amount of expensive fluoroolefin monomers. However, in reality, the applicable fields of application are limited because they are inadequate in terms of adhesion to substrates, pigment dispersibility and stain resistance. Is.

[0013]

However, the present inventors have found that the fluoroolefin-based monomer, which is expensive, does not impair the performance of the fluoroolefin-based aqueous coating composition known in the prior art. With the greatest aim of expanding the field of application of the composition by reducing various amounts of the compounds used and improving various properties such as adhesion to the base material and pigment dispersibility, diligent research has been conducted. Started.

Therefore, the problem to be solved by the present invention depends on the first problem, and the fluoroolefin-based monomers which are expensive without impairing the various performances of the fluoroolefin-based aqueous coating composition of this kind. It is intended to expand the field of application of the composition by reducing the amount of the composition used and improving various properties such as adhesion to a substrate and pigment dispersibility.

[0015]

SUMMARY OF THE INVENTION In view of the present situation, the inventors of the present invention have focused their attention on the problems to be solved by the invention as described above and have made diligent studies. It is possible to reduce the amount of the fluoroolefin monomer used for the first time by localizing the polymer, and in addition, when the obtained emulsion is used for an aqueous paint, its durability is improved. It is also possible to improve various performances such as adhesion to a base material and pigment dispersibility without impairing the
Upon finding out, the present invention has been completed.

That is, when preparing a fluoroolefin emulsion, a so-called core-shell polymerization method is used in which fluoroolefin units derived from fluoroolefin monomers are localized only on the relatively relatively large surface of the emulsion particles. For the first time, by discovering what can be achieved by applying,
The present invention has been completed.

That is, according to the present invention, basically, the inside of the particle is occupied by the resin derived from the fluorine atom-free monomers, while the outer shell of the particle is the fluorine atom-containing monomer. The present invention is intended to provide an aqueous dispersion of a core-shell type fluororesin (fluoroolefin-based copolymer emulsion), which is occupied by a resin derived from the class (fluoroolefin-based monomers), or ,

When preparing an aqueous resin dispersion by radical emulsion polymerization in the presence of an emulsifier in an aqueous medium, as a first step, monomers having no fluorine atom are polymerized to give a fluorine atom. To obtain an aqueous dispersion of a resin containing no fluorine, as a second step, in the presence of the aqueous dispersion of a resin containing no fluorine atom, monomers having at least one fluorine atom in one molecule are added. Consisting of polymerizing a monomer mixture as an essential component, while the inside of the particle is occupied by a resin derived from a monomer mixture which essentially comprises monomers having no fluorine atom The core-shell type fluororesin aqueous dispersion in which the outer shell of the particles is occupied by a resin derived from a monomer mixture containing fluorine atom-containing monomers (fluoroolefin-based monomers) as an essential component (Fluoro It is intended to provide even the manufacturing process of the fin copolymer emulsion),

At the same time, the inside of the particle is occupied by a resin derived from a monomer mixture containing a fluorine atom-free monomer as an essential component, while the outer shell of the particle is a fluorine atom-containing monomer. Such a specific core-shell type fluororesin aqueous dispersion (fluoroolefin copolymer emulsion), which is occupied by a resin derived from a monomer mixture in which the monomers are essential, is used as an essential film-forming component. The present invention is intended to provide an aqueous resin composition containing the same, and further to provide an application of the aqueous resin composition.

The core-shell type polymerization method referred to in the present invention is
Particles obtained by subjecting a monomer mixture having a different composition to a stepwise polymerization step of at least two stages in a method of radically emulsion polymerizing a monomer mixture in an aqueous medium in the presence of an emulsifier. It can be defined as a polymerization method of obtaining emulsion particles having different compositions along the radial direction of.

Specifically, for example, when two kinds of monomer mixture, that is, the monomer mixture A and the monomer mixture B, are used, first, the monomer mixture A is polymerized, and subsequently, By polymerizing the monomer mixture B, the polymer A obtained from the monomer mixture A exists inside the particle (core portion), and the monomer A exists in the outer shell (shell portion) of one particle. Emulsion particles in the form of polymer B obtained from mixture B are obtained.

As the polymerization in this case, the monomer mixture A may be polymerized and then the monomer mixture B may be continuously polymerized in the same reaction vessel, or After completion of the polymerization of the monomer mixture A, the product may be taken out once, and then the monomer mixture B may be polymerized, and further, as described above,
Polymerization of other types of monomers may be repeated in order to impart not only a two-step reaction but also a multi-layer structure, that is, a so-called multi-layer structure.

In the present invention, as the monomer mixture A, a monomer mixture containing fluorine atom-free monomers as an essential component is used, and the other monomer mixture is used. As B, a monomer mixture containing fluorine atom-containing monomers as an essential component is used.

Here, as the monomer mixture A,
That is, as a monomer mixture containing a monomer not having a fluorine atom as an essential component, first, carboxylic acid vinyl ester-based monomers can be mentioned. As specific examples, only vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate,
Vinyl caproate, vinyl 2-ethylhexanoate, vinyl versatate, vinyl laurate, vinyl stearate, vinyl salicylate, vinyl monochloroacetate, vinyl cyclohexanecarboxylate, vinyl p-tert-butylbenzoate, and the like,

Further, there are various kinds of carboxylic acid vinyl ester-based monomers such as "Veoba" (vinyl ester manufactured by Shell in the Netherlands), and among these monomers, particularly preferable. Examples include vinyl pivalate, vinyl caproate, vinyl 2-ethylhexanoate, vinyl versaticate (vinyl neononanoate, vinyl neodecanoate), vinyl laurate, vinyl stearate, vinyl cyclohexanecarboxylate, p-tert.
Examples thereof include vinyl esters of carboxylic acid having a linear, branched or cyclic alkyl structure having 5 or more carbon atoms, such as vinyl butyl benzoate or “Veova”.

As described above, the carboxylic acid moiety in the vinyl ester monomers of carboxylic acid has a linear, branched or cyclic alkyl structure having 5 or more carbon atoms in the acid. In order to improve the weather resistance of the coating, it is preferable, and more preferable that the number of carbon atoms be 6 or more.

That is, a straight chain having 5 or more carbon atoms,
The vinyl ester-based monomers of carboxylic acid having a branched or cyclic alkyl structure have a bulky alkyl group in terms of the molecular structure, and thus improve the water repellency of the finally obtained film, and thus the high temperature water or the base. It has the effect of suppressing the hydrolysis of the ester bond due to the organic substance.

Therefore, by using the monomers, it is possible to satisfy the long-term durability after the film formation. On the other hand, in the case of a vinyl ester of a carboxylic acid having less than 5 carbon atoms, although a film having good weather resistance can be obtained, there are problems in water resistance and alkali resistance over a long period of time.

Further, to exemplify only typical ones used as the above-mentioned monomer mixture A, methyl-, ethyl-, n-propyl-, isopropyl-, n-butyl-, Isoamyl-, n-hexyl-, n-octyl- or 2-ethylhexyl-
Alkyl vinyl ethers having various linear or branched alkyl groups such as vinyl ether; cyclopentyl vinyl ether, cyclohexyl vinyl ether or methyl

Cycloalkyl vinyl ethers having various (alkyl-substituted) cyclic alkyl groups such as cyclohexyl vinyl ether; or various aralkyl vinyl ethers such as benzyl vinyl ether or phenethyl vinyl ether; or 4-
Various vinyl ethers having a substituted or unsubstituted alkyl group, such as various hydroxyalkyl vinyl ethers such as hydroxybutyl vinyl ether,

2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3
-Hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 3-chloro-2-hydroxypropyl (meth) acrylate, polyethylene glycol Various hydroxyalkyl esters of (meth) acrylic acid, such as mono (meth) acrylates;

Further, hydroxyl group-containing monomers represented by various unsaturated group-containing polyhydroxyalkyl esters such as various kinds of polyhydroxycarboxylic acid dihydroxyalkyl esters such as maleic acid and fumaric acid. And so on

(Meth) acrylamide, N, N-dimethyl (meth) acrylamide, N-alkoxymethylated (meth) acrylamide, diacetone acrylamide,
Examples include various carboxylic acid amide group-containing monomers represented by N-methylol (meth) acrylamide and the like,

P-Styrenesulfonamide, N-methyl-p-styrenesulfonamide, N, N-dimethyl-p
-Various sulfonic acid amide group-containing monomers typified by styrene sulfonamide; various N, N-, such as N, N-dimethylaminoethyl (meth) acrylate
An adduct with a compound having both an active hydrogen group and a tertiary amino group capable of reacting with various polyvalent carboxylic acid anhydride group-containing monomers such as dialkylaminoalkyl (meth) acrylates or maleic anhydride. And various tertiary amino group-containing monomers represented by

Typical of (meth) acrylonitrile,
Various cyano group-containing monomers; Condensation of various kinds of hydroxyalkyl esters of α, β-ethylenically unsaturated carboxylic acids with various kinds of phosphoric acid esters such as (meth) acrylic acid hydroxyalkyl ester Various monomers having a phosphoric acid ester group obtained by the reaction;
Various types of monomers having a sulfonic acid group, such as 2-acrylamido-2-methylpropanesulfonic acid,

Methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-
(Meth) acrylic acid alkyl esters having various linear, branched or cyclic C _{1 to} C ₈ alkyl groups such as ethylhexyl (meth) acrylate and cyclohexyl (meth) acrylate; or styrene, α-methylstyrene, p-tert-butyl-
Various aromatic vinyl compounds such as styrene, p-methylstyrene, various styrenes or styrene derivatives,

Various (substituted) aromatic nucleus-containing (meth) acrylic acid esters such as benzyl (meth) acrylate; various unsaturated dicarboxylic acids such as maleic acid, fumaric acid and itaconic acid, and various monovalent compounds Diesters with alcohols; vinyl chloride, vinylidene chloride, ethylene,
Various olefins such as propylene and butene-1;
(Meth) acrylic acid or crotonic acid or maleic acid, fumaric acid, itaconic acid or citraconic acid, and further, various acid anhydride group-containing monomers such as maleic anhydride or itaconic anhydride, and various Examples thereof include carboxyl group-containing monomers or dicarboxylic acids represented by various unsaturated group-containing hydroxyalkyl ester monocarboxylic acids such as adducts with glycols.

Of these, the use of crotonic acid, itaconic acid, etc. is preferable from the viewpoint of copolymerizability. Here, the purpose of introducing the above-mentioned acid group-containing monomers is to improve the stability of the aqueous resin dispersion (polymer emulsion), and to the base material in the final use scene. This is to improve the adhesion.

Furthermore, what is used as the above-mentioned monomer mixture A includes so-called crosslinkable monomers, but only typical ones are exemplified as the crosslinkable monomers. If so, butadiene, hexadiene, octadiene, decadiene, tetradecadiene, 2-methyl-octadiene, decatriene, ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, divinylbenzene. , Trivinylbenzene, diallyl phthalate, various monomers having two or more polymerizable unsaturated groups in the molecule, or vinyltriethoxysilane, trimethoxysilylvinylether, γ- (meth ) Acryloyloxypropyltrimethoxy Silane, .gamma. (meth) acryloyloxy propyl methyl dimethoxy silane, .gamma. (meth) acryloyloxy propyl triethoxysilane,
Examples include various hydrolyzable silyl group-containing monomers such as γ- (meth) acryloyloxypropylmethyldiethoxysilane.

Of these, selected from the group consisting of hexadiene, octadiene, decadiene, tetradecadiene, 2-methyl-octadiene and decatriene.
One kind or a mixture of two or more kinds and / or vinyltriethoxysilane, γ- (meth) acryloyloxypropyltrimethoxysilane, γ- (meth) acryloyloxypropylmethyldimethoxysilane, γ- (meth)
Acryloyloxypropyltriethoxysilane, γ-
Since the use of various hydrolyzable silyl group-containing monomers such as (meth) acryloyloxypropylmethyldiethoxysilane and tris (2-methoxyethoxy) vinylsilane gives a stable aqueous resin dispersion, desirable.

The purpose of introducing the crosslinkable monomers is to improve so-called durability such as water resistance, alkali resistance and solvent resistance, or to use a polymer having a low glass transition point. This is because the coating obtained from the polymer has toughness.

These monomers are appropriately selected in consideration of the glass transition point and the minimum film forming temperature of the finally obtained copolymer. A combination of carboxylic acid vinyl ester-based monomers, olefins, carboxyl group-containing monomers and crosslinkable monomers is preferable. The above is a description of the main components constituting the monomer mixture A in the present invention.

Next, only representative examples of the fluorine atom-containing monomers (fluoroolefin-based monomers) which are essential as the above-mentioned monomer mixture B will be exemplified. Monomers are vinyl fluoride, vinylidene fluoride, tetrafluoroethylene,
Hexafluoropropylene, 1,1,3,3,3-pentafluoropropylene, 2,2,3,3-tetrafluoropropylene, 1,1,2-trifluoropropylene,
Examples include 3,3,3-trifluoropropylene, chlorotrifluoroethylene, bromotrifluoroethylene, 1-chloro-1,2-difluoroethylene, and 1,1-dichloro-2,2-difluoroethylene.

Of these, at least one fluoroolefin-based monomer selected from the group consisting of hexafluoropropylene, chlorotrifluoroethylene and vinylidene fluoride is preferably used. It is more preferable to use chlorotrifluoroethylene from the viewpoint of controlling the reaction during polymerization.

As the monomers other than the fluorine atom-containing monomers constituting the monomer mixture B, the monomer mixture A
As described above, various monomers can be used.

These above-mentioned monomers are appropriately selected in consideration of the glass transition point and the minimum film forming temperature of the copolymer finally obtained. Preferably, in addition to fluoroolefin monomers, as monomers copolymerizable with these, carboxylic acid vinyl ester monomers,
Combinations of olefins, carboxyl group-containing monomers and / or crosslinkable monomers are suitable.

Next, the above-mentioned emulsifier is used in order to stably disperse the above-mentioned various monomers in an aqueous medium, and in addition, in the final use mode, the various properties of the film are sufficient. The anionic emulsifier having no fluorine atom and / or the nonionic emulsifier having no fluorine atom is preferably used. Specific examples include the following.

That is, first of all, only representative examples of anionic emulsifiers containing fluorine atoms (including reactive emulsifiers) will be given. Alkyl (benzene) sulfonates and alkylsulfates ,
Examples include polyoxyethylene alkylphenol sulfate salts, styrene sulfonate salts, vinyl sulfate salts and various derivatives thereof.

The salt as used herein refers to a salt of an alkali metal hydroxide or a salt of a so-called volatile base such as ammonia or triethylamine. Among these, it is particularly preferable to use one or a mixture of two or more selected from the group consisting of (substituted) alkyl (benzene) sulfonates and vinyl sulfonates.

Then, as nonionic emulsifiers having no fluorine atom (including reactive emulsifiers), only typical ones will be exemplified. Polyoxyethylene alkylphenol ether, polyoxyethylene alkyl ether, polyoxyethylene alkyl ether Oxyethylene higher fatty acid ester, ethylene oxide-propylene oxide block copolymer and various derivatives thereof, and the like,
These may be used alone or in combination of two or more,
Of course.

Of these, the use of polyoxyethylene (substituted) alkyl (phenyl) ether is preferable also from the viewpoint of various physical properties of the film finally obtained.
The amount of these various emulsifiers to be used is preferably within a range of 0.5 to 10% based on the total weight of the monomers including the anionic emulsifier and the nonionic emulsifier. .

Furthermore, in combination with these emulsifiers,
Water-soluble oligomers consisting of polycarboxylic acids or sulfonates, various water-soluble polymeric substances such as polyvinyl alcohol or hydroxyethyl cellulose,
It can be used as a so-called protective colloid.

Here, "having no fluorine atom"
Meaning is as follows. Usually, the polymerization of fluoroolefin-based monomers in an aqueous medium is carried out by using a fluorine atom-containing emulsifier, but in the conventional system, such a fluorine atom-containing emulsifier is inevitably used. Therefore, the surface of the particle has relatively low energy. Therefore, if the aqueous resin dispersion (polymer emulsion) obtained according to the prior art is applied to a substrate, there is a drawback that adhesion to the substrate is inevitably poor.

In the present invention, in order to overcome such drawbacks, the polymerization in the form of a fluorine atom-free emulsifier system is suitable and preferable. However, it does not hinder the combined use of a fluorine atom-containing emulsifier typified by perfluorooctanoic acid salt.

The core-shell type polymer emulsion of the present invention, or the core-shell type polymer emulsion obtained according to the method of the present invention, contains various monomers as listed above in the presence of the emulsifier. It is obtained by polymerizing in an aqueous medium.

The polymerization initiator used at that time is
The emulsion polymerization is not particularly limited as long as it is generally used.

Specific examples include various water-soluble inorganic peroxides such as hydrogen peroxide; various persulfates such as ammonium persulfate, potassium persulfate and sodium persulfate;
Various organic peroxides such as cumene hydroperoxide, benzoyl peroxide and t-butyl hydroperoxide; various azo initiators such as azobisisobutyronitrile and azobiscyanovaleric acid However, it goes without saying that these may be used alone or in combination of two or more kinds.

The amount of the polymerization initiator used is appropriately within the range of 0.1 to 2% by weight based on the total amount of monomers. Needless to say, a so-called redox polymerization method in which these polymerization initiators are used in combination with a metal ion and a reducing agent may be used.

Specific examples of such reducing agents include sodium bisulfite, sodium metabisulfite, sodium bithiosulfate, sodium hydrosulfate, sodium sulfoxylate formaldehyde sodium or reducing sugars, and the above metal ion. Particularly, only representative examples are copper sulfate, ferric chloride, ferric sulfate or silver nitrate. Furthermore, various chain transfer agents can also be used.

In the present invention, in the presence of an aqueous medium, preferably ion-exchanged water and an emulsifier, first, the monomer mixture A as it is or in an emulsified state is batched or divided, Alternatively, the emulsion polymer A is continuously or dropwise added to the reaction vessel and polymerized in the presence of the polymerization initiator at a reaction temperature within the range of about 50 ° C to 100 ° C. To prepare.

Then, in the presence of the polymer A thus obtained, the monomer mixture B is similarly, as it is, or in an emulsified state, in a batch, divided or in a reaction vessel. In the presence of the above-mentioned polymerization initiator, about 1 kg / cm ^{2 to} 100 kg / c.
With a gauge pressure within the range of m ² , and approximately 50 ° C to 1
Polymerization may be carried out at a reaction temperature within the range of 50 ° C. Depending on the case, there is no problem even if the pressure is higher than this or the temperature condition is lower than this.

In this case, the ratio of the monomer mixture A and the monomer mixture B is 70 to 1 of the monomer mixture A.
A suitable mixing ratio is 30 to 90 parts by weight of the monomer mixture B relative to 0 parts by weight. In this case, the ratio of the core and the shell is the same as the case of the charging ratio,
The core portion is in the range of 70 to 10 parts by weight, while the shell is in the range of 30 to 90 parts by weight, whereby a core-shell type polymer emulsion having such a ratio is obtained.

The amount of the fluoroolefin-based monomers contained in the total monomers should be approximately 30% by weight or more. If it is less than this range, satisfactory results cannot be obtained in terms of so-called durability of the film finally obtained.

The ratio of the total amount of monomers to water is such that the final solid content is 1 to 60% by weight, preferably 15%.
The range of up to 55% by weight is suitable, but the ratio should be set to such a range.

Further, in carrying out emulsion polymerization of the monomer mixture A, emulsion particles may be present in the aqueous phase in advance so as to grow or control the particle size, and then the polymerization may be carried out. Of course.

As the water in the aqueous medium used here, ion exchanged water is basically suitable, but the amount of such water needs to be 70% by weight or more in the aqueous medium. Is. Here, organic solvents may be used together with the remaining less than 30% by weight. Here, the organic solvents are not particularly limited, and any general-purpose organic solvents can be used.

As the organic solvents, only typical ones are listed, and various kinds of ketones such as acetone, methyl ethyl ketone and methyl amyl ketone; various kinds of esters such as ethyl acetate and butyl acetate; Various aromatic hydrocarbons such as benzene, toluene and xylene; various aliphatic hydrocarbons such as hexane and heptane; various alcohols such as methanol, ethanol, isopropanol, butanol; carbon tetrachloride, methylene Examples of the halogen-containing organic solvent include various freon-based solvents such as dichloride and hexafluoroisopropanol.

The polymerization reaction has a pH of about 1.0 in the system.
The pH may be adjusted by using a so-called pH buffering agent such as disodium phosphate or borax, or sodium hydrogencarbonate or ammonia. You can do it. Under a pH condition higher than this, when a film is formed, only a film having a so-called lack of durability such as water resistance and alkali resistance can be obtained, which causes deterioration of various performances.

In this way, the core-shell type polymer emulsion of the present invention can be obtained. The state of the system after completion of the reaction is that emulsion particles contain very few unreacted gaseous monomers. It is said that some of them remain. Most of such residual monomers are unreacted fluoroolefin monomers, but in order to prevent the emulsion from being destroyed and to be stably removed,
You should do the following:

That is, after neutralizing all or part of the acidic groups based on the acid group-containing monomers converted to the polymer with a basic substance, the unreacted monomers are removed. Alternatively, the unreacted monomers may be removed after adding the silicon compound and / or the mineral oil compound.

To exemplify only the typical examples of the basic substance, sodium hydroxide,
Examples thereof include alkali metal hydroxides such as potassium hydroxide; various organic amines such as triethylamine; and ammonia. Of these, particularly preferable are organic amines such as triethylamine and ammonia. Such as volatile basic substances.

In addition, the above silicon compounds and /
Alternatively, as the mineral oil-based compound, a commercially available and commonly used aqueous defoaming agent may be used.

As a method for removing unreacted monomers, unreacted gaseous monomers are added at room temperature or under heating conditions of 100 ° C. or lower under normal pressure or reduced pressure. By the method of removing the kind,
It is also possible to use a steam distillation method or the like. At this time, so-called inert gas such as nitrogen gas, by bubbling through the system, to promote the removal of unreacted gaseous monomers, thereby,
The effect of removal can be increased.

The core-shell type polymer emulsion of the present invention, or the core-shell type polymer emulsion obtained by the method of the present invention, is converted into a state in which there are no crosslinkable monomers, and the number average molecular weight is about , 5,000
The range of 0 to 1,000,000 is suitable, and the weight average molecular weight is 10,000 to 3,000,0.
The range of 00 is suitable, and the minimum film-forming temperature is suitably within the range of 0 ° C to 60 ° C. Further, as the particle diameter of the core-shell polymer, in general,
The range of 0.02 to 0.5 micron (μm) is suitable.

The core-shell type polymer emulsion according to the present invention may be further blended with thickeners, film-forming aids and the like to form an aqueous resin composition or an aqueous coating composition. I can. As the thickeners used at this time, cellulose-based thickeners represented by hydroxyethyl cellulose, carboxymethyl cellulose and the like; urethane-based thickeners; polycarboxylic acid-based thickeners and the like can be used.

As the above-mentioned film-forming aids, in addition to the various solvents mentioned above, ester-based compounds such as ethylene glycol; or ether-based derivatives; or ester-based compounds such as diethylene glycol; or ether. System derivatives; Furthermore, plasticizers, which are commonly used for water-based paints, represented by "Texanol" (produced by Eastman Chemical Company, USA) can be used.

In addition to these, titanium oxide, mica,
Various inorganic pigments such as talc, clay, precipitated barium sulfate, silica powder, calcium carbonate, iron oxide, zinc oxide, aluminum powder, carbon black; various organic pigments such as azo, phthalocyanine and quinacridone Or plastic pigments; or these various pigments can be used in the form of dispersed pigments in water by using an emulsifier or dispersant, etc., depending on the final purpose of each. , Is appropriately selected.

Further, as various additives necessary for coating, for example, dispersants, wetting agents, thixotropic agents, ultraviolet absorbers, antioxidants, water repellents, antifreezing agents. The use of antiseptic / antifungal agents, antifoaming agents and the like is appropriately selected and used in consideration of various properties of the obtained film.

Thus, an aqueous resin composition containing the core-shell type polymer emulsion can be obtained. When applying such an aqueous resin composition to various substrates, there is no particular limitation, but one example is as follows. Brush coating, roller coating, spray coating, roll coater coating, or showering coating is preferable.

At this time, for construction site construction, it is desirable to use a paint having a minimum film-forming temperature of 0 ° C. or lower with a film-forming auxiliary added, and the coating method is brush, roller or spray. It is better to use such a method as above, but for so-called factory line painting for various roofing materials and wall materials such as roof tiles, according to the generally used forced heating drying method, according to the drying conditions. It is desirable to select and use a paint having a minimum film-forming temperature of about 60 ° C. or less, preferably 50 ° C. or less, with a film-forming auxiliary being added. As a coating method, a roll coater or a roller can be used. ,
It is preferable to use a method such as spraying, showering, a flow coater, or dip coating such as depping.

Whether it is for such on-site construction or for factory line coating or heating forced drying line coating, it is of course one method to dry at room temperature, but by any means, at a temperature of 60 ° C. or more, In order to carry out in an atmosphere at a temperature of 200 ° C. or less, after coating, if necessary, after setting time, by heat drying, the film-forming property or film-forming property is further enhanced. In order to ensure long-term durability of the film,
It is also desirable in order to reduce blocking as much as possible and to secure stain resistance.

Further, one coat of the above-mentioned aqueous resin composition or aqueous coating composition, or an aqueous resin composition or aqueous coating composition containing a pigment and the like is directly coated on the substrate. Or may be applied by multiple coating, or an acrylic copolymer, an acrylic-styrene copolymer system, an acrylic-urethane combined system, a silicon-acrylic combined system, an epoxy system, a urethane system. Alternatively, a coating material containing a binder, which generally has good alkali resistance, such as a silicon-based material, is used as an undercoat, and as a top coat, an aqueous resin dispersion (polymer emulsion) or an aqueous resin composition or The water-based coating composition may be applied to improve the weather resistance of the entire coating system.

In any of the coating systems described above, an aqueous resin composition or an aqueous coating composition containing a core-shell type polymer emulsion as an essential film forming component, or an aqueous solution containing a pigment and the like is used. The dry film thickness of the resin composition or the aqueous coating composition is 5 μm
m or more is suitable.

This is because if the thickness is less than 5 μm, the long-term durability of the coating tends to be insufficient.

Thus, according to the present invention or according to the method of the present invention, various film properties such as super weatherability, water resistance, chemical resistance and stain resistance are excellent.
A protective coating on the substrate is formed.

Examples of the base material used in the present invention include cement mortar, cement concrete, and AL.
C, asbestos concrete, wood cement board, calcium silicate board, etc., a hardened body (concrete skeleton, wall material or roof material, etc.) prepared by hydrating and crystallizing an alkaline substance is particularly typical. Is. In addition to these base materials, it can be applied to metals, plastics, woods, glasses, papers or fibers.

The core-shell type polymer emulsion according to the present invention is characterized in that it has excellent weather resistance, chemical resistance, stain resistance of the film, and excellent boiling water resistance for a long period of time and alkali resistance at high temperatures. Therefore, it can be widely used as an aqueous coating composition for exterior or interior, and further as a coating agent or a treating agent for metals, plastics, woods, inorganic substrates, papers, fibers and the like. .

[0088]

EXAMPLES Next, the present invention will be described more specifically with reference to Examples, Comparative Examples, Applied Technology Examples and Comparative Applied Technology Examples. In the following, all parts and% are all unless otherwise specified. It shall be based on weight.

Example 1 (Preparation example of core-shell type fluororesin aqueous dispersion) A pressure resistant reaction made of stainless steel having an inner volume of 2 liters (l) equipped with a stirrer, a nitrogen inlet tube, a thermometer and a temperature controller. Fill the container (autoclave) with nitrogen gas,
The system was sufficiently replaced, and 800 g of ion-exchanged water, 20 g of sodium dodecylbenzenesulfonate, 20 g of polyoxyethylene nonylphenyl ether, and 10 g of borax as a pH buffer were added and dissolved.

Next, 350 g of vinyl acetate and 10 g of hexadiene were charged, and ethylene gas was added at 15 k.
It was pressed in until it reached g / cm ² . The internal temperature of the autoclave was raised to 80 ° C. At this time, ethylene gas was adjusted so that the system pressure during the reaction was about 25 kg / cm ² .

At the same temperature, 2 g of potassium persulfate was added to 10
An aqueous catalyst solution dissolved in 0 g of ion-exchanged water was pressed into the reaction vessel over 1 hour. Even after the addition of the aqueous catalyst solution, the temperature was kept at the same temperature for 2 hours to continue the polymerization reaction to obtain a polymer emulsion having no fluorine atom.

Then, 200 g of vinyl neodecanoate, 10 g of crotonic acid, and 300 g of liquefied and collected chlorotrifluoroethylene were charged into this reaction vessel. After that, ethylene gas was injected under pressure until the pressure reached 30 kg / cm ² , and the internal temperature of the autoclave was adjusted to 80 ° C.
The temperature was raised to. At this time, ethylene gas was adjusted so that the pressure in the system during the reaction was about 30 kg / cm ² .

Subsequently, at the same temperature, an aqueous catalyst solution prepared by dissolving 3 g of potassium persulfate in 100 g of ion-exchanged water was pressed into the reaction vessel for 3 hours. After adding the aqueous catalyst solution, hold at the same temperature for 10 hours,
The polymerization reaction was allowed to continue.

The reaction was carried out at a pH of 3.5 during the reaction. During the reaction, the pressure in the system decreased as the monomer was consumed, but the pressure of the reaction system was maintained at 30 kg / cm ² by introducing ethylene each time.

After the reaction was completed, the reaction mixture was cooled to room temperature and kept at 14%.
Ammonia water was added until the pH reached about 7.5, and 1 g of a 5% aqueous dispersion of "Nopco 8034L" [a silicon defoamer manufactured by San Nopco] was added,
Well, stirred.

Next, the unreacted gas was gradually taken out of the system, and the pressure inside the system was returned to normal pressure.

After that, the unreacted gas dissolved in the dispersion was distilled off under reduced pressure. The dispersion obtained here has a nonvolatile content of 49.5%, a pH of 7.2,
Minimum film forming temperature is 35 ° C and average particle size is 0.08
It was a white core-shell type polymer emulsion having a size of μm. Hereinafter, this is abbreviated as (A-1).

(A-1) was found to have a fluoroolefin monomer content of about 30% by weight as a result of compositional analysis by elemental analysis, ion chromatography analysis, infrared absorption spectrum and pyrolysis gas chromatography. It was confirmed that there is.

Example 2 (Preparation example of core-shell type fluororesin aqueous dispersion) A 2 liter stainless steel pressure-resistant reaction vessel (autoclave) equipped with a stirrer, a nitrogen inlet tube, a thermometer and a temperature controller was charged with nitrogen gas. After replacing the inside of the system sufficiently,
800 g of ion-exchanged water, 20 g of sodium dodecylbenzene sulfonate, 20 g of polyoxyethylene nonylphenyl ether, and 10 g of borax as a pH buffer were added and dissolved.

Next, 180 g of vinyl acetate, 60 g of neononanoic acid and 10 g of tris (2-methoxyethoxy) vinylsilane were charged, and ethylene gas was added to 15 g.
It was press-fitted until it became kg / cm ² . The internal temperature of the autoclave was raised to 80 ° C., and at this time, the system internal pressure during the reaction was adjusted to approximately 25 kg / cm ² .
Ethylene gas was adjusted.

Thereafter, at the same temperature, an aqueous catalyst solution prepared by dissolving 2 g of potassium persulfate in 100 g of ion-exchanged water was pressed into the reaction vessel for 1 hour. Even after the addition of the aqueous catalyst solution, the polymerization reaction was continued at the same temperature for 10 hours to obtain a polymer emulsion having no fluorine atom.

Next, 280 g of vinyl 2-ethylhexanoate, 20 g of crotonic acid, and 350 g of chlorotrifluoroethylene liquefied and collected were charged under pressure into this reaction vessel, and further ethylene gas was adjusted to 30 kg / cm ^2. The pressure inside the autoclave to 80 ° C.
Adjusted to. At this time, the system pressure is about 30 kg /
Ethylene gas was adjusted to be cm ² .

Subsequently, at the same temperature, an aqueous catalyst solution prepared by dissolving 3 g of potassium persulfate in 100 g of ion-exchanged water was pressed into the reaction vessel for 3 hours. After adding the aqueous catalyst solution, hold at the same temperature for 10 hours,
The polymerization reaction was allowed to continue.

The pH of the reaction proceeded at 3.5. During the reaction, the pressure in the system decreased as the monomers were consumed, but the pressure of the reaction system was maintained at 30 kg / cm ² by introducing ethylene each time.

After completion of the reaction, cool to room temperature and
% Ammonia water was added until the pH reached approximately 7.5, and 1 g of a 5% aqueous dispersion of "Nopco 8034L" was further added and stirred well.

Then, the unreacted gas was gradually taken out from the system, and the system pressure was returned to normal pressure.

Then, the unreacted gas dissolved in the dispersion was distilled off under reduced pressure. The obtained dispersion is a white core-shell type polymer emulsion having a nonvolatile content of 48.8%, a pH of 7.4, a minimum film forming temperature of 20 ° C., and an average particle diameter of 0.09 μm. Met.
Hereinafter, this is abbreviated as (A-2).

This (A-2) was found to have a fluoroolefin monomer abundance of about 34 wt% by elemental analysis, ion chromatography analysis, infrared absorption spectrum, and composition analysis by thermal decomposition gas chromatography. % Was confirmed.

Comparative Example 1 (Preparation Example of Polymer Emulsion of Uniform Composition) A 2 liter stainless steel pressure-resistant reaction vessel (autoclave) equipped with a stirrer, a nitrogen inlet tube, a thermometer and a temperature controller was purged with nitrogen gas. Then, the system was sufficiently replaced, and 800 g of ion-exchanged water, 20 g of sodium dodecylbenzenesulfonate, 20 g of polyoxyethylene nonylphenyl ether, and 10 g of borax as a pH buffer were added and dissolved.

Next, 350 g of vinyl acetate and 10 g of hexadiene were charged, and 20 g of vinyl neodecanoate was added.
0 g and 10 g of crotonic acid were also charged, and 300 g of chlorotrifluoroethylene liquefied and collected was also charged.

Subsequently, ethylene gas was added at 15 kg / c.
It was pressed in until it reached m ² . The internal temperature of the autoclave is 80
The temperature in the system during the reaction is almost
Ethylene gas was adjusted to 30 kg / cm ² .

Further, at the same temperature, 5 g of potassium persulfate was added.
Of the catalyst aqueous solution dissolved in 200 g of ion-exchanged water,
It was pressed into the reaction vessel for 3 hours. After adding the aqueous catalyst solution, hold at the same temperature for 10 hours,
The polymerization reaction was continued to obtain a control polymer emulsion having no fluorine atom. The pH during the reaction proceeded at 3.5.

During the reaction, the pressure in the system decreased with the consumption of the monomers, and the pressure of the reaction system was kept at 30 kg / cm ² by introducing ethylene each time.

After the reaction was completed, the reaction mixture was cooled to room temperature and
% Ammonia water is added until the pH becomes about 7.5, and 1 g of a 5% aqueous dispersion of "Nopco 8034L" is further added, and after stirring well, the unreacted gas is added.
The system was gradually taken out from the system and the system pressure was returned to normal pressure.

Then, the unreacted gas dissolved in the dispersion was distilled off under reduced pressure. The control dispersion obtained here has a non-volatile content of 49.8% and a pH of 7.2.
And the minimum film forming temperature is 38 ° C., and the average particle size is 0.
It was a white core-shell type polymer emulsion having a diameter of 08 μm. Hereinafter, this is abbreviated as (B-1).

This (B-1) was analyzed by elemental analysis, ion chromatography analysis, infrared absorption spectrum, and composition analysis by pyrolysis gas chromatography to find that the abundance of fluoroolefin monomers was about 30% by weight. % Was confirmed.

Comparative Example 2 A control dispersion containing no crosslinkable monomers was obtained in the same manner as in Example 1 except that the use of hexadiene was changed to omit it. Hereafter, this (C-
It is abbreviated as 1).

This (C-1) was subjected to salting out according to a conventional method to take out only the polymer component. Next, the free emulsifier was extracted with ion-exchanged water, followed by drying and then dissolving in tetrahydrofuran.

The sample thus obtained was subjected to gel filtration chromatography to measure the polystyrene-equivalent molecular weight. The obtained result shows that the number average molecular weight is 162,0.
And the weight average molecular weight was 537,000, which corresponds to the molecular weight obtained by removing the crosslinkable monomers from (A-1) described above.

Comparative Example 3 A control sample containing no crosslinkable monomers in the same manner as in Example 2 except that the use of tris (2-methoxyethoxy) vinylsilane was changed so as to be omitted altogether. A dispersion of Hereinafter, this is abbreviated as (C-2).

This (C-2) was subjected to salting out according to a conventional method to take out only the polymer component. Next, the free emulsifier was extracted with ion-exchanged water, followed by drying and then dissolving in tetrahydrofuran.

The sample thus obtained was subjected to gel filtration chromatography to measure the polystyrene-equivalent molecular weight. The obtained result shows that the number average molecular weight is 177,0.
The weight average molecular weight was 00 and the weight average molecular weight was 559,000, which corresponds to the molecular weight obtained by removing the crosslinking from (A-2) described above.

Applied Technology Examples 1 and 2 and Comparative Applied Technology Example 1 These examples are prepared by using the various fluororesin aqueous dispersions obtained in Examples 1 and 2 and Comparative Example 1, respectively, to prepare an aqueous paint. A composition was prepared, and various water-based coating compositions were evaluated and evaluated for various properties.

First, the above-mentioned various fluororesin aqueous dispersions were diluted so that the non-volatile content was 45%, and "Boncoat 3750" as a thickening agent [Poly Nippon Daika Chemical Industry Co., Ltd.] was used. Of carboxylic acid-based polymer thickener]
Add 2% of the diluted aqueous solution, thicken it with 14% ammonia water, and add 2% of "texanol" as a film-forming aid to each resin for various aqueous paints. A composition was obtained.

Then, each of the compositions thus obtained was coated on a slate plate with a No. 60 bar coater and dried at 60 ° C. for 20 minutes. After that, dry at room temperature for 7 days,
Various specimens were prepared. Then, various performance evaluation tests were carried out on each of the specimens.

The results of those tests are summarized in Table 1.

[0127]

[Table 1]

<< Footnote in Table 1 >><Test Items and Evaluation Criteria> “Water resistance” ... The state of the coating film after being immersed in tap water for 2 months was visually determined. .

∘: No abnormalities in appearance X: Abnormalities such as swelling, peeling, or whitening on the coating film

"Alkali resistance" ... The state of the coating film after being immersed in 2% NaOH saturated with Ca (OH) ₂ for 2 months was visually evaluated.

∘: No external appearance is found. ×: Abnormalities such as swelling, peeling or whitening are observed on the coating film.

"Accelerated weather resistance" ............ "Accelerated weather resistance" is an abbreviation, and after a test for 3,000 hours with a dew panel light control weather meter, the appearance of each coating film is visually inspected. It was judged.

∘: No external appearance abnormality △: Appearance of gloss on the coating film ×: Appearance of swelling, peeling or whitening on the coating film

The core-shell type fluororesin aqueous dispersion (polymer emulsion) according to the present invention has good pigment dispersibility without impairing weather resistance as compared with a control product having a uniform composition.
In addition, it will be seen that it gives a film or coating which also has good adhesion to substrates.

[0135]

INDUSTRIAL APPLICABILITY As described above, the core-shell type polymer emulsion according to the present invention can disperse the pigment by arranging the fluorine atoms, as compared with the fluororesin emulsion having a uniform composition, without impairing the weather resistance. A water-based resin composition having good properties and good adhesion to a substrate is provided.

Claims (9)

[Claims] 1. The inside of the particle is occupied by a resin derived from a monomer having no fluorine atom, while the outer shell of the particle is occupied by a resin derived from a fluorine atom-containing monomer. An aqueous dispersion of a core-shell type fluororesin, which is characterized by being present. 2. The aqueous dispersion of a core-shell type fluororesin according to claim 1, wherein the monomers having no fluorine atom have vinyl carboxylate as an essential component. 3. The aqueous dispersion of a core-shell type fluororesin according to claim 1, wherein the fluorine atom-containing monomers have fluoroolefin-based monomers as an essential component. 4. When preparing an aqueous resin dispersion by radical emulsion polymerization in the presence of an emulsifier in an aqueous medium, as a first step, monomers having no fluorine atom are treated as essential components. Polymerize the monomer mixture to
Obtaining an aqueous dispersion of a fluorine-free resin, the second step is the monomer having at least one fluorine atom in one molecule in the presence of the aqueous dispersion of a fluorine-free resin. Characterized by polymerizing a monomer mixture having a group of essential components, the inside of the particle is occupied by a resin derived from monomers having no fluorine atom, while the particle outer shell, A method for producing an aqueous dispersion of a core-shell type fluororesin, which is occupied by a resin derived from fluorine atom-containing monomers. 5. The method for producing an aqueous core-shell type fluororesin dispersion according to claim 4, wherein the monomer mixture to be polymerized in the first step contains a carboxylic acid vinyl ester as an essential component. . 6. The core-shell type fluororesin aqueous dispersion according to claim 4, wherein the monomer mixture to be polymerized in the second step has fluoroolefin-based monomers as an essential component. Manufacturing method. 7. The inside of the particle is occupied by a resin derived from a monomer having no fluorine atom, while the outer shell of the particle is occupied by a resin derived from a fluorine atom-containing monomer. An aqueous resin composition comprising an aqueous dispersion of a core-shell type fluororesin as an essential film-forming component. 8. The inside of the particle is occupied by a resin derived from a monomer having no fluorine atom, while the outer shell of the particle is occupied by a resin derived from a fluorine atom-containing monomer. A core-shell type fluororesin aqueous dispersion (A),
The aqueous resin composition according to claim 7, which contains a thickener (B), a film-forming auxiliary (C), and water (D) as essential components. 9. An article coated with the aqueous resin composition according to claim 7 and dried.