JP3278003B2 - Production method of fluororesin aqueous dispersion and its application - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention provides a new and useful
The present invention relates to a method for producing an aqueous dispersion of a fluororesin and its application. More specifically, the present invention relates to a core-shell type fluororesin aqueous dispersion obtained by using chlorotrifluoroethylene as an essential component, a method for producing the same, and its application, and in particular, can be suitably used for coating.
The present invention relates to a core-shell polymer emulsion, a method for producing the same, and applications.

[0002]

2. Description of the Related Art In the field of exterior coating materials, in recent years,
There is a great demand for a coating material that is extremely practical and has no deterioration or discoloration over a long period of time. Particularly, in the field of civil engineering and construction, coating of the surface of a so-called alkaline inorganic cured material such as a concrete frame, a wall material or a roof material is carried out. , Water resistance and weather resistance.

Among these coating materials, aqueous organic polymer materials such as acrylic copolymers and acrylic-styrene copolymers are widely used because of their simple coating treatment.

[0004] However, especially when used as building exterior materials, those having a life of at least 10 years or more, and moreover, semi-permanent ones are being demanded, and acrylic copolymers and acrylic-styrene are required. When an aqueous polymer such as a system copolymer is used for the top coat, it is difficult to say that the weather resistance is sufficient, and as a result, recoating is required within a short period of time.

[0005] On the other hand, fluoroolefin copolymers are known as binders that provide high weather resistance and high chemical resistance, and organic solvent solutions are already commercially available.

However, since commercially available binders contain organic solvents, they have problems in terms of fire danger, harmfulness, air pollution, and the like, and aqueous binders are required.

On the other hand, tetrafluoroethylene,
Although the use of aqueous dispersions of polymers (fluoroolefin polymers) such as vinylidene fluoride or hexafluoropropylene has been proposed, all of these polymers require baking at high temperatures. That is.

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

Therefore, even in the case of architectural paints which need to form a coating film at room temperature or factory paints which rely on forced drying, the above-mentioned high-temperature baking is not practically practical. It is possible and not suitable for such applications.

Further, the fluoroolefin-based monomers are expensive, so that the copolymer is
It is disadvantageous from an economical point of being composed only of the fluoroolefin-based monomers.

Japanese Patent Application Laid-Open No. 61-26167 discloses a method for solving various problems as described above, which comprises a fluoroolefin, an alkyl vinyl ether, and a carboxylic acid vinyl ester.
An emulsion copolymer-based coating resin composition has been disclosed, and as an exterior coating material, it can be said that it is suitable for the time being. It is insufficient in terms of dispersibility and stain resistance.

As described above, as far as the prior art is concerned, a water-based coating composition containing a highly durable fluoroolefin unit as a main component uses a relatively large amount of expensive fluoroolefin-based monomers. The fact is that it is not sufficient in terms of adhesion to the substrate, dispersibility of the pigment, and stain resistance. It is.

[0013]

SUMMARY OF THE INVENTION However, the present inventors have proposed an expensive fluoroolefin-based monomer without impairing the performance of any of the fluoroolefin-based aqueous coating compositions known in the prior art. With the greatest aim of expanding the field of application of the composition by reducing the amount of the compounds used and improving various properties such as adhesion to the base material and dispersibility of the pigment, Started.

Accordingly, an object of the present invention is to provide, in part, an expensive fluoroolefin-based monomer without impairing the performance of the fluoroolefin-based aqueous coating composition of this kind. The purpose of the present invention is 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 dispersibility of a pigment.

[0015]

Means for Solving the Problems In view of the present situation, the present inventors have conducted intensive studies with the aim of solving the problems to be solved by the invention as described above. By localizing, the amount of the fluoroolefin-based monomer used can be reduced for the first time, and in addition, when the obtained emulsion is used for water-based paint, its durability can be reduced. Without impairing the ability to improve various properties such as adhesion to the substrate and pigment dispersibility,
Upon finding out, the present invention has been completed.

That is, in preparing a fluoroolefin-based emulsion, a unit derived from a monomer mixture containing chlorotrifluoroethylene as an essential component is relatively localized only on the surface of the emulsion particles, so-called core-shell. For the first time, the present inventors have found out what can be achieved by applying a pattern polymerization method, and have now completed the present invention.

[0017]

That is, in the present invention, in preparing an aqueous resin dispersion by radical emulsion polymerization in an aqueous medium in the presence of an emulsifier, as a first step, monomers having no fluorine atom are used. Polymerizing to obtain an aqueous dispersion of a fluorine atom-free resin; as a second step, a simple process comprising chlorotrifluoroethylene as an essential component in the presence of the fluorine atom-free resin aqueous dispersion; While the inside of the particle is occupied by a resin derived from a monomer mixture essentially comprising monomers having no fluorine atom, which consists of polymerizing the monomer mixture, the outer shell of the particle is ,
It is intended to provide a method for producing a core-shell type fluororesin aqueous dispersion, which is occupied by a resin derived from a monomer mixture containing chlorotrifluoroethylene as an essential component,

At the same time, while the inside of the particles is occupied by a resin derived from a monomer mixture containing a monomer containing no fluorine atom as an essential component, the outer shell of the particles is made of chlorotrifluoroethylene. An aqueous resin composition comprising such a specific core-shell type fluororesin aqueous dispersion as an essential film-forming component, such as being occupied by a resin derived from a monomer mixture having an essential component, It is intended to provide an application of the aqueous resin composition.

The core-shell polymerization method referred to in the present invention is:
In a method of subjecting a monomer mixture to radical emulsion polymerization in an aqueous medium in the presence of an emulsifier, a particle mixture obtained by subjecting a monomer mixture having a different composition to at least two stages of a stepwise polymerization step. It can be defined as a polymerization method in which emulsion particles having different compositions are obtained along the radial direction.

Specifically, for example, when two types of monomer mixtures, monomer mixture A and monomer mixture B, are used, first, monomer mixture A is polymerized, and then, By polymerizing the monomer mixture B, the polymer A obtained from the monomer mixture A is present inside the particles (core part), and the monomer outer shell (shell part) is contained in one particle outer shell (shell part). Emulsion particles in the form of the presence of the polymer B obtained from the mixture B are obtained.

In this case, the polymerization of the monomer mixture A may be performed, and then the polymerization of the monomer mixture B may be continued in the same reaction vessel. After the completion of the polymerization of the monomer mixture A, the product may be taken out once, and thereafter, the polymerization of the monomer mixture B may be carried out.
In addition to the reaction of only two steps, polymerization of other types of monomers may be repeated to give a multi-layer structure, that is, a so-called multilayer structure.

In the present invention, as the monomer mixture A, a monomer mixture containing a monomer containing no fluorine atom as an essential component is used, and the other monomer mixture is used. As B, a monomer mixture containing chlorotrifluoroethylene as an essential component is used.

Here, as the monomer mixture A,
That is, as a monomer mixture containing a monomer having no fluorine atom as an essential component, first, a carboxylate vinyl ester-based monomer may be mentioned. As particularly typical examples only, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate,
Including vinyl caproate, vinyl 2-ethylhexanoate, vinyl versatate, vinyl laurate, vinyl stearate, vinyl salicylate, vinyl monochloroacetate, vinyl cyclohexanecarboxylate or vinyl p-tert-butylbenzoate,

Further, various kinds of vinyl ester monomers of carboxylic acid, such as "Veoba" (vinyl ester manufactured by Shell Co., The Netherlands), are particularly preferable among these monomers. Examples include vinyl pivalate, vinyl caproate, vinyl 2-ethylhexanoate, vinyl versatate (vinyl neononanoate, vinyl neodecanoate), vinyl laurate, vinyl stearate, vinyl cyclohexanecarboxylate, p-tert.
And vinyl esters of carboxylic acids having a linear, branched or cyclic alkyl structure having 5 or more carbon atoms, such as vinyl butyl benzoate or "Veoba".

As described above, the carboxylic acid moiety in the carboxylic acid vinyl ester monomer has a straight-chain, branched or cyclic alkyl structure having 5 or more carbon atoms in the acid. In order to enhance the weather resistance and the like of the film, a material having a carbon number of 6 or more is more preferable.

That is, a straight chain having 5 or more carbon atoms
Vinyl ester monomers of a carboxylic acid having a branched or cyclic alkyl structure have a bulky alkyl group in the molecular structure, so that the water repellency of the finally obtained film is improved, and high-temperature water or base This has the effect of suppressing the hydrolysis of the ester bond due to an acidic substance or the like.

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

Further, if only typical ones used as the monomer mixture A are exemplified, 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

Various cycloalkyl vinyl ethers having a (alkyl-substituted) cyclic alkyl group, such as cyclohexyl vinyl ether; or various aralkyl vinyl ethers, such as benzyl vinyl ether or phenethyl vinyl ether;
Vinyl ethers having various substituted or unsubstituted alkyl groups, 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) acrylate;

Or hydroxyl-containing monomers represented by various unsaturated group-containing polyhydroxyalkyl esters, such as 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,
Various carboxylic acid amide group-containing monomers, such as N-methylol (meth) acrylamide;

P-styrenesulfonamide, N-methyl-p-styrenesulfonamide, N, N-dimethyl-p
-Various sulfonic acid amide group-containing monomers represented by styrene sulfonamide and the like; various N, N- monomers such as N, N-dimethylaminoethyl (meth) acrylate
Dialkylaminoalkyl (meth) acrylates or adducts with compounds having both an active hydrogen group and a tertiary amino group, which can react with various polycarboxylic acid anhydride group-containing monomers such as maleic anhydride And various tertiary amino group-containing monomers.

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

Methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-
Alkyl (meth) acrylates having various C _{1 to} C ₈ , linear, branched or cyclic alkyl groups, such as ethylhexyl (meth) acrylate and cyclohexyl (meth) acrylate; or styrene, α-methylstyrene, p-tert-butyl-
Styrene, various kinds of aromatic vinyl compounds such as p-methylstyrene, various kinds of styrene or styrene derivatives, and the like;

Various (substituted) aromatic nucleus-containing (meth) acrylates such as benzyl (meth) acrylate; various unsaturated dicarboxylic acids such as maleic acid, fumaric acid and itaconic acid and various monovalent acids Diesters with alcohols; vinyl chloride, vinylidene chloride, ethylene,
Various olefins such as propylene and butene-1;
Various acid anhydride group-containing monomers such as (meth) acrylic acid or crotonic acid or maleic acid, fumaric acid, itaconic acid or citraconic acid, and also various maleic anhydride- or itaconic anhydride-containing monomers. And carboxyl group-containing monomers or dicarboxylic acids typified by various unsaturated group-containing hydroxyalkyl esters / monocarboxylic acids, such as adducts with glycols.

Of these, the use of crotonic acid or itaconic acid is desirable 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. This is to improve the adhesion.

Further, there is a so-called crosslinkable monomer as the monomer mixture A, but only typical representative examples of the crosslinkable monomer are given below. If so, butadiene, hexadiene, octadiene, decadiene, tetradecadiene, 2-methyl-octadiene, decatriene, ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, trimethylolpropanetri (meth) acrylate, divinylbenzene , Trivinylbenzene, diallyl phthalate, and various monomers having two or more polymerizable unsaturated groups in the molecule, or vinyltriethoxysilane, trimethoxysilylvinylether, γ- (meta ) Acryloyloxypropyl trimethoxy Silane, .gamma. (meth) acryloyloxy propyl methyl dimethoxy silane, .gamma. (meth) acryloyloxy propyl triethoxysilane,
Various hydrolyzable silyl group-containing monomers such as γ- (meth) acryloyloxypropylmethyldiethoxysilane.

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

The purpose of introducing the crosslinkable monomers is to improve the so-called durability such as water resistance, alkali resistance and solvent resistance, or use a polymer having a low glass transition point. In addition, it is for imparting toughness to a film obtained from the polymer.

These monomers are appropriately selected in consideration of the glass transition point, the minimum film forming temperature, and the like of the finally obtained copolymer. Preferably, a combination of a carboxylic acid vinyl ester monomer, an olefin, a carboxyl group-containing monomer and a crosslinkable monomer is suitable. The main components constituting the monomer mixture A according to the present invention have been described above.

Next, chlorotrifluoroethylene is used as an essential component as the monomer mixture B,
In addition, as fluorine atom-containing monomers (fluoroolefin monomers), for example, vinyl fluoride, vinylidene fluoride, tetrafluoroethylene, hexafluoropropylene, 1,1,3,3,3-pentafluoropropylene , 2,2,3,3-tetrafluoropropylene, 1,
1,2-trifluoropropylene, 3,3,3-trifluoropropylene, chlorotrifluoroethylene, bromotrifluoroethylene, 1-chloro-1,2-difluoroethylene or 1,1-dichloro-2,2-difluoro Ethylene or the like can be used.

From the viewpoint of controlling the reaction during the polymerization, it is desirable to use chlorotrifluoroethylene.

The monomers other than the fluorine atom-containing monomers constituting the monomer mixture B include the monomer mixture A
Various monomers as described above can be used.

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

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

That is, first, as typical anionic emulsifiers (including reactive emulsifiers) having no fluorine atom, only typical ones are exemplified, and alkyl (benzene) sulfonate and alkyl sulfate salt are exemplified. ,
Polyoxyethylene alkylphenol sulfate, styrene sulfonate, vinyl sulfate and various derivatives thereof.

As used herein, the term "salt" refers to a salt derived from a hydroxide of an alkali metal or a salt derived from a so-called volatile base such as ammonia or triethylamine. Among these, it is particularly desirable to use one or two or more mixtures selected from the group consisting of (substituted) alkyl (benzene) sulfonic acid salts and vinylsulfonic acid salts.

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

Among these, the use of polyoxyethylene (substituted) alkyl (phenyl) ether is desirable also from the viewpoint of the physical properties of the finally obtained film.
The amount of use of these various emulsifiers is appropriately in the range of 0.5 to 10% based on the total weight of the monomers, including the anionic emulsifier and the nonionic emulsifier. .

Further, in combination with these emulsifiers,
Water-soluble oligomers composed of polycarboxylic acid or sulfonic acid salt, various water-soluble polymer substances such as polyvinyl alcohol or hydroxyethyl cellulose,
It can be used as a so-called protective colloid.

Here, “having no fluorine atom”
The meaning is as follows. Usually, the polymerization of fluoroolefin monomers in an aqueous medium is carried out using a fluorine atom-containing emulsifier, but in conventional systems, such a fluorine atom-containing emulsifier is inevitably used. The surface of the particles is relatively low energy. Therefore, when an aqueous resin dispersion (polymer emulsion) obtained according to the prior art is applied to a substrate, there is a disadvantage that the adhesion to the substrate is inevitably poor.

In the present invention, in order to overcome such drawbacks, it is preferable and preferable to carry out polymerization in an emulsifier system having no fluorine atom. However, the use of a fluorine atom-containing emulsifier, such as a perfluorooctanoate, is never prevented.

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

The polymerization initiator used at that time includes:
In the emulsion polymerization, there is no particular limitation 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-based initiators such as azobisisobutyronitrile and azobiscyanovaleric acid. However, these may be used alone or in combination of two or more.

The amount of the polymerization initiator used is suitably in the range of 0.1 to 2% by weight based on the total amount of monomers. It is needless to say that 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 a reducing agent include sodium bisulfite, sodium metabisulfite, sodium bithiosulfate, sodium hydrosulfate, sodium formaldehyde sulfoxylate, reducing sugar, and the like. Particularly representative examples are copper sulfate, ferric chloride, ferric sulfate and silver nitrate. Further, various chain transfer agents can be used.

In the present invention, first, in the coexistence 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 collectively or divided into Alternatively, it is added or dropped into a reaction vessel continuously, and polymerization is carried out at a reaction temperature in the range of about 50 ° C. to 100 ° C. in the presence of the polymerization initiator. Is prepared.

Next, in the presence of the polymer A thus obtained, the monomer mixture B is also placed in the reaction vessel, as it is, or in an emulsified state, collectively, dividedly or continuously. To about 1 kg / cm ^{2 to} 100 kg / c in the presence of the polymerization initiator.
at a gauge pressure in the range of m ² and about 50 ° C. to 1
The polymerization may be carried out at a reaction temperature within a range of 50 ° C. Depending on the case, there is no problem even if the pressure is higher than this or the temperature is lower than this.

Here, the ratio of the monomer mixture A to the monomer mixture B is 70 to 1 of the monomer mixture A.
A suitable mixing ratio is such that the monomer mixture B is 30 to 90 parts by weight with respect to 0 parts by weight. In this case, the ratio between the core and the shell is the same as the charge ratio,
While the core is in the range of 70 to 10 parts by weight, 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.

It is necessary that the amount of chlorotrifluoroethylene contained in the total monomers is generally at least 30% by weight. If it is less than this, satisfactory results cannot be obtained in terms of the so-called durability of the finally obtained film.

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% by weight.
The range of about 55% by weight is appropriate, but the ratio should be set to such a ratio.

Further, in carrying out the emulsion polymerization of the monomer mixture A, in order to grow or control the particle diameter, the emulsion particles may be allowed to exist in an aqueous phase before polymerization. Of course.

As the water in the aqueous medium used here, it is basically appropriate to use ion-exchanged water, but the amount of such water must be 70% by weight or more in the aqueous medium. It is. Here, an organic solvent may be used together with the remaining less than 30% by weight. Here, the organic solvent is not particularly limited, and any general-purpose organic solvent can be used.

As the organic solvents, only typical ones are exemplified, and various ketones such as acetone, methyl ethyl ketone and methyl amyl ketone; various 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 and butanol; carbon tetrachloride, methylene Halogen-containing organic solvents including various chlorofluorocarbon solvents such as dichloride and hexafluoroisopropanol.

In the polymerization reaction, when the pH in the system is approximately 1.0
The pH may be adjusted by using a so-called pH buffer such as disodium phosphate or borax, or sodium bicarbonate or ammonia. Just 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 is a cause of deterioration in various performances.

In this way, the core-shell type polymer emulsion of the present invention is obtained. The state of the system after the completion of the reaction is such that unreacted gaseous monomers are extremely contained in the emulsion particles. Partly, it is surviving. Most of such residual monomers are unreacted fluoroolefin monomers, but in order not to destroy the emulsion, and to remove it stably,
You should do the following:

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

As the basic substances mentioned here, only typical ones are exemplified.
Hydroxides of alkali metals such as potassium hydroxide; various organic amines such as triethylamine; and ammonia. Of these, particularly preferred are organic amines such as triethylamine and ammonia. And volatile base materials.

Further, the above-mentioned silicon compound and / or
Alternatively, as the mineral oil-based compound, a known and commonly used aqueous defoaming agent may be used.

As a method for removing unreacted monomers, unreacted gaseous monomers may be removed at room temperature or under a heating condition of 100 ° C. or less under normal pressure or reduced pressure. By removing the creatures,
It can also be by using a steam distillation method or the like. At this time, a so-called inert gas such as nitrogen gas is bubbled into the system to promote the removal of unreacted gaseous monomers.
The effect of the removal can be increased.

The core-shell type polymer emulsion obtained by the method of the present invention has a number average molecular weight of about 5,000 in terms of a state having no crosslinkable monomers.
The range of 0 to 1,000,000 is appropriate, and the weight average molecular weight is 10,000 to 3,000,000.
00 is appropriate, and the minimum film forming temperature is suitably in the range of about 0 ° C to 60 ° C. Further, as the particle diameter of the core-shell polymer, generally,
A range of 0.02 to 0.5 microns (μm) is appropriate.

The core-shell type polymer emulsion according to the present invention may be further blended with a thickener, a film-forming auxiliary, etc. to form an aqueous resin composition or an aqueous coating composition. I can do it. As the thickener used in this case, a cellulose thickener represented by hydroxyethylcellulose, carboxymethylcellulose and the like; a urethane thickener; and a polycarboxylic acid thickener can be used.

The above-mentioned film-forming aids include, in addition to the above-mentioned various solvents, ester-based derivatives such as ethylene glycol; or ether-based derivatives; or ester-based derivatives such as diethylene glycol; or ether. Derivatives; plasticizers, such as "Texanol" (manufactured by Eastman Chemical Co., USA), commonly used for water-based paints, 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, and 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 a dispersion pigment dispersed in water with an emulsifier or dispersant, depending on the final purpose. , As appropriate.

Further, various additives necessary for forming a coating material include, for example, dispersants, wetting agents, thixotropic agents, ultraviolet absorbers, antioxidants, water repellents, and antifreeze agents. The use of antiseptic, antiseptic or antifoaming agents is appropriately selected and used in consideration of various properties of the obtained film.

Thus, an aqueous resin composition containing a core-shell type polymer emulsion can be obtained. When applying such an aqueous resin composition to various substrates, there is no particular limitation. It is preferable to use brush coating, roller coating, spray coating, roll coater coating, or showering coating.

At this time, for construction site construction, it is desirable to use a paint having a minimum film-forming temperature of 0 ° C. or less with a film-forming aid added. The coating method is a brush, roller or spray. It is better to use such a method, and for roofing and wall materials, such as tiles, for so-called factory line painting, according to the general heating and forced drying method, and according to the drying conditions. It is desirable to select and use a coating material having a minimum film forming temperature of about 60 ° C. or lower, preferably 50 ° C. or lower, in a state in which the film forming aids are added. The coating method includes a roll coater and a roller. ,
It is preferable to use a method such as spraying, showering, flow coater, or dip coating such as dipping.

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

The above-mentioned aqueous resin composition or aqueous coating composition containing the above-mentioned aqueous resin composition or aqueous coating composition or a pigment is directly coated on the substrate in one coat. , Or overcoating, or may be applied, or an acrylic copolymer, an acrylic-styrene copolymer, an acrylic-urethane combined system, a silicon-acryl combined system, an epoxy system, a urethane system. Or, a coating material containing a binder, which generally has good alkali resistance, such as a silicon-based material, is coated with an undercoat, and then, as a top coat, these aqueous resin dispersions (polymer emulsions) or aqueous resin compositions or The aqueous coating composition may be applied to improve and improve the weather resistance and the like of the entire coating system.

In any of the above coating systems, 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 resin composition containing a pigment or the like is used. As the dry film thickness of the resin composition or the aqueous coating composition, 5μ
m or more is appropriate.

When the thickness is less than 5 μm, the long-term durability of the film tends to be insufficient.

Thus, according to the method of the present invention, a protective film of a substrate is formed which is excellent in various film properties such as super weather resistance, water resistance, chemical resistance and stain resistance.

The base material in the present invention includes, for example, cement mortar, cement concrete, AL
Particularly typical is a hardened material (concrete frame, wall material or roof material) prepared by hydrating and crystallizing an alkaline substance, such as C, asbestos concrete, wood cement board, or calcium silicate board. It is. In addition to these substrates, it can be applied to metals, plastics, woods, glasses, papers, fibers, and the like.

The core-shell type polymer emulsion according to the present invention is characterized by being excellent in the weather resistance, chemical resistance, and stain resistance of the coating film, and the long-term boiling water resistance and the 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 or 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 technical examples and comparative applied technical examples. In the following, all parts and percentages are all unless otherwise specified. It shall be based on weight.

Example 1 (Preparation Example of Core-Shell Fluororesin Aqueous Dispersion) A stainless steel pressure-resistant reaction equipped with a stirrer, a nitrogen inlet tube, a thermometer and a temperature controller and having an inner volume of 2 liters (l) The container (autoclave) is filled 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 to 15 k
g / cm ² . The internal temperature of the autoclave was raised to 80 ° C. At this time, ethylene gas was adjusted so that the pressure in the system during the reaction was approximately 25 kg / cm ² .

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

Next, 200 g of vinyl neodecanoate, 10 g of crotonic acid, and 300 g of liquefied and collected chlorotrifluoroethylene were charged into the reaction vessel. Thereafter, ethylene gas was injected until the pressure reached 30 kg / cm ² , and the internal temperature of the autoclave was raised 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 approximately 30 kg / cm ² .

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

The reaction was allowed to proceed at a pH of 3.5. During this reaction, as the monomer was consumed, the pressure in the system decreased. In each case, the pressure of the reaction system was maintained at 30 kg / cm ² by introducing ethylene.

After completion of the reaction, the mixture is cooled to room temperature and
Aqueous ammonia was added until the pH became approximately 7.5, and 1 g of a 5% aqueous dispersion of “NOPCO 8034L” [silicon antifoaming agent manufactured by San Nopco] was added.
Stir well.

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

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

(A-1) was analyzed by elemental analysis, ion chromatography analysis, infrared absorption spectrum and compositional analysis by pyrolysis gas chromatography to find that the content of the fluoroolefin monomer was about 30% by weight. It was confirmed that there was.

Example 2 (Preparation Example of Core-Shell 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 filled with nitrogen gas. Thus, after sufficiently replacing the system,
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, 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 of ethylene gas.
It was press-fitted until it reached kg / cm ² . The internal temperature of the autoclave was raised to 80 ° C., and at this time, the pressure in the system during the reaction was adjusted to approximately 25 kg / cm ² .
The ethylene gas was adjusted.

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

Then, 280 g of vinyl 2-ethylhexanoate, 20 g of crotonic acid, and 350 g of chlorotrifluoroethylene collected by liquefaction were introduced into this reaction vessel, and ethylene gas was further reduced to 30 kg / cm ^2. And then raise the internal temperature of the autoclave to 80 ° C.
Was adjusted to At this time, the pressure in the system is approximately 30 kg /
The ethylene gas was adjusted so as to be cm ² .

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

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

After completion of the reaction, the reaction mixture is cooled to room temperature and
% Ammonia water was added until the pH was approximately 7.5, and 1 g of a 5% aqueous dispersion of "Nopco 8034L" was added, followed by thorough stirring.

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

Thereafter, unreacted gas dissolved in the dispersion was distilled off under reduced pressure. The resulting dispersion has a white core-shell 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 size of 0.09 μm. Met.
Hereinafter, this is abbreviated as (A-2).

This (A-2) was analyzed by elemental analysis, ion chromatography, infrared absorption spectrum and compositional analysis by pyrolysis gas chromatography to show that the content of the fluoroolefin monomer was about 34% by weight. %.

Comparative Example 1 (Example of Preparing 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. After sufficiently replacing the inside of the system, 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.

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

Subsequently, ethylene gas was supplied at 15 kg / c.
Press-fit until m ² . Autoclave internal temperature 80
° C, where the pressure in the system during the reaction is almost
Ethylene gas was adjusted to be 30 kg / cm ² .

Further, at the same temperature, 5 g of potassium persulfate was added.
Was dissolved in 200 g of ion exchanged water,
It was pressed into the reaction vessel for 3 hours. After addition of the catalyst aqueous solution, the temperature is maintained for 10 hours at the same temperature,
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. Each time, the pressure in the reaction system was maintained at 30 kg / cm ² by introducing ethylene.

After completion of the reaction, the reaction mixture is cooled to room temperature and
% Ammonia water is added until the pH becomes approximately 7.5, 1 g of a 5% aqueous dispersion of "Nopco 8034L" is added, and the mixture is stirred well.
The system was gradually removed from the system and the internal pressure was returned to normal pressure.

Next, unreacted gas dissolved in the dispersion was distilled off under reduced pressure. The control dispersion obtained here had a non-volatile content of 49.8% and a pH of 7.2.
, The minimum film forming temperature is 38 ° C., and the average particle diameter is 0.3.
It was a white core-shell polymer emulsion having a thickness of 08 µm. Hereinafter, this is abbreviated as (B-1).

This (B-1) was found to have a fluoroolefin monomer content of about 30% by elemental analysis, ion chromatography analysis, infrared absorption spectrum and compositional analysis by pyrolysis gas chromatography. %.

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 so that the use of hexadiene was completely omitted. Hereinafter, this is referred to as (C-
Abbreviated as 1).

This (C-1) was subjected to salting out according to a conventional method, and only a polymer component was taken out. Next, a free emulsifier was extracted with ion-exchanged water, and then dried, and then dissolved in tetrahydrofuran.

The obtained sample was subjected to gel filtration chromatography to measure the molecular weight in terms of polystyrene. The result obtained is that the number average molecular weight is 162,0
It was 00 and the weight average molecular weight was 537,000, which corresponds to the molecular weight of (A-1) excluding the crosslinkable monomers.

Comparative Example 3 A control 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 completely omitted. Was obtained. Hereinafter, this is abbreviated as (C-2).

This (C-2) was subjected to salting out according to a conventional method, and only a polymer component was taken out. Next, a free emulsifier was extracted with ion-exchanged water, and then dried, and then dissolved in tetrahydrofuran.

The obtained sample was subjected to gel filtration chromatography to measure the molecular weight in terms of polystyrene. The results obtained show that the number average molecular weight is 177,0.
It was 00 and the weight average molecular weight was 559,000, which corresponds to the above-mentioned (A-2), the molecular weight of which the cross-linking was omitted.

Applied Technical Examples 1 and 2 and Comparative Applied Technical Example 1 These examples were prepared using aqueous fluororesin dispersions obtained in Examples 1 and 2 and Comparative Example 1, respectively. The compositions were prepared, and the various water-based paint compositions were evaluated for various properties.

First, the above-mentioned various fluororesin aqueous dispersions were diluted so that the nonvolatile content became 45%, and “Boncoat 3750” as a thickener [Polymer manufactured by Dainippon Ink and Chemicals, Inc. 5% of carboxylic acid-based polymer thickener]
Add 2% of the diluted aqueous solution, thicken it with 14% aqueous ammonia, and further add 2% each of “Texanol” as a film-forming aid to various water-based paint resins. A composition was obtained.

Next, each of the compositions thus obtained was applied on a slate plate using a No. 60 bar coater, and dried at 60 ° C. for 20 minutes. After that, let it dry at room temperature for 7 days,
Various specimens were prepared. Then, various performance evaluation tests were performed on each specimen.

Table 1 summarizes the results of these tests.

[0127]

[Table 1]

<< Footnotes in Table 1 >><Test Items and Evaluation Criteria>"Waterresistance" ... The state of the coating film after being immersed in tap water for 2 months was visually judged. .

A: No abnormality in appearance ×: An abnormality such as blistering, peeling, or whitening was observed in 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 judged.

◎: No appearance defect in appearance ×: Appearance of abnormality such as blistering, peeling or whitening in the coating film

"Accelerated weathering resistance": Abbreviation of "accelerated weathering resistance": After performing a test for 3,000 hours using a dual panel light control weather meter, the appearance of each coating film was visually observed. Judged.

A: No abnormality in appearance. B: Gloss is observed in the coating. X: Blistering, peeling, and whitening are observed in the coating.

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 appreciated that it also provides a film or coating with good adhesion to the substrate.

[0135]

As described above, the core-shell type polymer emulsion according to the production method of the present invention is capable of localizing fluorine atoms as compared with a fluororesin emulsion having a uniform composition, so that the weather resistance is not impaired. , Good pigment dispersibility,
In addition, an aqueous resin composition having good adhesion to a substrate is provided.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) C08F 291/00-291/18

Claims (5)

(57) [Claims] When preparing an aqueous resin dispersion by radical emulsion polymerization in the presence of an emulsifier in an aqueous medium, as a first step, a monomer having no fluorine atom is used as an essential component. Polymerize the monomer mixture
To obtain an aqueous dispersion of a fluorine-free resin, as a second step, a monomer mixture containing chlorotrifluoroethylene as an essential component in the presence of the aqueous dispersion of a fluorine-free resin The inside of the particles, which is characterized by being polymerized, is occupied by a resin derived from monomers having no fluorine atom, while the outer shell of the particles is chlorotrifluoro.
A process for producing an aqueous dispersion of a core-shell type fluororesin occupied by a resin derived from a monomer mixture containing ethylene as an essential component . 2. The production of an aqueous dispersion of a core-shell type fluororesin according to claim 1, wherein the monomer mixture to be polymerized in the first stage contains vinyl carboxylate as an essential component. Law. 3. An aqueous resin composition comprising the core-shell type fluororesin aqueous dispersion obtained by the production method according to claim 1 or 2 as an essential film-forming component. 4. The aqueous resin composition according to claim 3 , further comprising a thickener, a film-forming auxiliary, and water as essential components. 5. An article coated with the aqueous resin composition according to claim 3 and dried.