JPH0627124B2 - Fine resin particles and manufacturing method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to fine resin particles and a method for producing the same, and particularly uses thereof, particularly fine resin particles exhibiting good dispersibility in a liquid dispersion medium, a method for producing the same, and a coating composition utilizing the above characteristics. Regarding things.

A polymer emulsion obtained by emulsion-polymerizing one or more polymerizable monomers in water is also called a synthetic latex, and is widely used as an aqueous paint or an adhesive in the form of an emulsion. The stability of the emulsion also depends on the amount of the emulsifier and protective colloid used, and the stability increases in direct proportion to the amount used. Commonly used emulsifiers are anionic or nonionic surfactants,
The protective colloid is a water-soluble polymer such as CMC, PVA and hydroxyethyl cellulose. Therefore, the presence of these emulsifiers and protective colloids is essential for synthetic latex paints, but is an impurity for dried coatings, and their presence in large amounts adversely affects the performance of coatings, especially water resistance and weather resistance. It will be. Therefore, it has been desired to develop an emulsifier or protective colloid that serves to stabilize the emulsion as an emulsifier or protective colloid during the emulsifier polymerization, but does not deteriorate the performance even if it remains in the coating film.

The present inventors have conducted various studies in search of an emulsifier or protective colloid capable of responding to the above demands, and as a result, a compound having a zwitterionic group at substantially both ends of the molecule as a dispersant when polymerizing a polymerizable monomer is used. It has been found that, when used, resin particles having an extremely fine particle size are produced, but on the other hand, the fine resin particles can be dispersed in a liquid medium, particularly an aqueous medium with satisfactory stability. Conventionally,
Resin particle size obtained by emulsion polymerization is 0.2μ at best
While it is around (2000Å), the particle size of the resin particles obtained by using the above specific dispersant is 100.
Since it is ~ 1000Å, it is no exaggeration to say that it is ultrafine particles. On the other hand, in order to maintain such ultrafine particles in a stable dispersed state, a fairly large amount of emulsifier should be required, but as long as the above specific dispersant is used, a stable dispersed state can be obtained even in a relatively small amount. Can be maintained. Further, when a large amount of a normal emulsifier is used, the coating performance is deteriorated as described above.However, if the above specific dispersant is used, the coating performance is deteriorated even if it is a relatively large amount. It is not allowed. Rather, because the resin particles are ultra-fine, the coating film performance is clearly superior to conventional emulsion resins.

The present invention has been completed based on the above discovery, and the gist thereof is (1) (A) one or more monomers having at least one polymerizable ethylenically unsaturated group. A number average particle size (n) of 100 comprising a polymer and a dispersant having a zwitterionic group (B) at substantially both ends of the molecule.
~ 1000Å, particle size distribution (w / n) of 1.0 to 3.0 and good dispersibility in liquid medium, (2) In the presence of a polymerization initiator, zwitterionics are present at both ends of the molecule. In a liquid medium containing a dispersant having a group, one or more monomers having at least one polymerizable ethylenically unsaturated group are polymerized to obtain a number average particle size (n) of 100 to 1000Å, particles. Diameter distribution (w
/ N) a dispersion of resin particles having 1.0 to 3.0, and if necessary, removing the liquid medium from the dispersion to obtain fine resin particles, a method for producing fine resin particles, (3 ) (A) Containing a polymer composed of one or more kinds of monomers having at least one polymerizable ethylenically unsaturated group, and (B) a dispersant having a zwitterionic group at substantially both ends of the molecule. Number average particle size (n) 100
˜1000Å, fine resin particles having a particle size distribution (w / n) of 1.0 to 3.0 are dispersed in a liquid medium for coating.

The fine resin particles of the present invention have at least one polymerizable ethylenically unsaturated group in a liquid medium containing a dispersant having a zwitterionic group substantially at both ends of the molecule in the presence of a polymerization initiator. It can be produced by polymerizing one or more of the monomers it has.

A feature of the above production method is that a compound having a zwitterionic group at substantially both ends of the molecule is used as a dispersant. If the zwitterionic group is present in the molecule but its position is not substantially at the terminal of the molecule, or if it is present at only one of the terminals, then the resin particles produced are not sufficiently fine. And does not have satisfactory dispersion stability.

There are no particular restrictions on the types of zwitterionic groups,
A typical example is shown by:(In the formula, R₁And R_TwoAre the same or different
And may contain -O- and / or -COO-.
Alkyl group or cycloalkyl having no more than 20 carbon atoms
Group or R₁And R_TwoJoin together and combine them
Represents a nitrogen-containing heterocycle with a nitrogen atom_ThreeIs
Alkylene which may be replaced but does not exceed 8 carbon atoms
Represents a group, and Y is CO_Two , SO_Three Or PO_Four To
Represent. )(In the formula, R_FourIncludes -O- and / or -COO-
Occasionally alkyl groups or siku having no more than 20 carbon atoms
Represents a lower alkyl group, R₅May have been replaced
Represents an alkylene group having 8 or less carbon atoms, and Z is CO
_Two , SO_Three Or PO_Four Represents ).

A compound having such a zwitterionic group at both ends of the molecular chain is used as a dispersant in the present invention, but the intermediate part of the molecular chain sandwiched by these zwitterionic groups is nonionic. It is preferable that
It may be a molecular chain normally considered to be lipophilic or hydrophobic, such as an alkylene chain or a polyether chain. Thus, specific examples of dispersants include the following compounds: Such.

Examples of the monomer having at least one polymerizable ethylenic unsaturated group include the following: (a) Hydroxyl group-containing monomer (eg, 2-hydroxyethyl acrylate, hydroxypropyl acrylate, 2 -Hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, hydroxybutyl methacrylate, allyl alcohol, methallyl alcohol, etc.), (b) carboxyl group-containing monomer (for example, acrylic acid, methacrylic acid, crotonic acid, itaconic acid, Maleic acid, fumaric acid, derivatives thereof, etc.), (c) glycidyl group-containing monomer (eg, glycidyl acrylate, glycidyl methacrylate, etc.), (d) alkyl acrylate or methacrylate (eg, Chill acrylate, methyl methacrylate,
Ethyl acrylate, ethyl methacrylate, n-butyl acrylate, n-butyl methacrylate, 2-ethylhexyl acrylate, etc.), (e) Nitrogen-containing alkyl acrylate or methacrylate (for example, N, N-dimethylaminoethyl acrylate, N, N-dimethylamino) Ethylmethacrylate etc.), (f) polymerizable amide (eg acrylic acid amide, methacrylic acid amide, n-butoxymethylacrylamide etc.), (g) polymerizable nitrile (eg acrylonitrile, methacrylonitrile etc.), (h) Polymerizable aromatic compound (for example, styrene, α-methylstyrene, vinyltoluene, t-butylstyrene, etc.), (i) α-olefin compound (for example, ethylene, propylene, etc.), (j) Vinyl compound (for example, acetic acid) Vinyl, propionic acid Sulfonyl, etc.), (k) a diene compound (e.g., butadiene, isoprene, etc.).

In addition, the polyfunctional monomers exemplified below can also be used: ethylene glycol diacrylate, ethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, 1,3-butylene dimethacrylate, 1 3,3-butylene glycol dimethacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, 1,4-butanediol acrylate, neopentyl glycol diacrylate, 1,6-hexanediol diacrylate, pentaerythritol diacrylate, pentaerythritol Triacrylate, pentaerythritol tetraacrylate, pentaerythritol dimethacrylate, pentaerythritol trimethacrylate, pen Taerythritol tetramethacrylate, glycerol dimethacrylate, glycerol diacrylate, glycerol acryloxymethacrylate, 1,1,1-trishydroxymethylethane diacrylate, 1,1,1-trishydroxymethylethane triacrylate, 1,1,1- Trishydroxymethylethane dimethacrylate, 1,1,1-trishydroxymethylethane methacrylate, 1,1,1-trishydroxymethylpropane diacrylate, 1,1,1-trishydroxymethylpropane triacrylate, 1,1,1 -Trishydroxymethylpropane dimethacrylate, 1,1,1-trishydroxymethylpropane trimethacrylate, triallyl cyanurate, triallyl trimellitate, diallyl terephthalate, diallyl phthalate and divinylbenzene. What.

As the polymerization initiator, usual ones can be used, for example, organic peroxides such as benzoyl peroxide, t-butyl peroxide, cumene hydroperoxide, azobiscyanovaleric acid, azobisisobutyronitrile, azobis-
(2,4-dimethyl) valeronitrile, azobis- (2-
Amidino bropan) Hydrochloride and other organic azo compounds, potassium persulfate, ammonium persulfate, sodium persulfate, inorganic water-soluble radical initiators such as hydrogen peroxide, these inorganic water-soluble radical initiators and sodium pyrosulfite, hydrogen sulfite Examples thereof include redox initiators obtained by combining sodium, divalent iron ions and the like, and one kind or a mixture of two or more kinds thereof is used.

An aqueous medium is generally used as the liquid medium, but the liquid medium is not limited thereto, and an oil medium may be used. The aqueous medium may be composed only of water, but a hydrophilic solvent such as methanol, ethanol, methyl cellosolve or ethyl cellosolve may be mixed therein.

The polymerization is preferably carried out in the presence of the above-mentioned polymerization initiator by dropping the polymerizable monomer into a liquid medium containing the above-mentioned dispersant, particularly an aqueous medium.

The amount of the polymerization initiator used may be selected in the range of usually 0.05 to 5% (weight), preferably 0.1 to 3%, based on the weight of the polymerizable monomer. The dispersant is usually 0.1 to 10% (by weight), preferably 0.3 to 8%, based on the weight of the polymerizable monomer.
Particularly preferably, 0.5 to 6% is used.

The liquid medium contains resin particles (solid content) of 2 to 65%
It is preferable to use (weight), particularly 20 to 60%. When the liquid medium is an aqueous medium, an appropriate amount of a base may be added to improve the solubility of the dispersant depending on the type of the dispersant. As the base, alkali hydroxide, ammonia, or organic amine can be used, but ammonia or organic amine that volatilizes to leave no inorganic ion in the coating film is preferable. If necessary, a usual chain transfer agent (for example, mercaptans such as lauryl mercaptan) may be used in an appropriate amount.

Other polymerization operations and conditions may be performed according to a conventional emulsion polymerization method.

As a result of the above polymerization reaction, a dispersion in which fine resin particles, which are the polymerization reaction products, are stably dispersed is obtained. The fine resin particles are composed of a polymer obtained by polymerizing the polymerizable monomer used in the polymerization reaction and a dispersant surrounding the polymer, and usually have a number average particle diameter (n) of 100 to 10
00Å, particle size distribution (w / n) 1.0 to 3.0.

The number average particle diameter and the particle diameter distribution are N by an electron microscope.
The particle diameter D of each sample is measured and is a value obtained by the following equation (the number of particle diameters Di is Ni, and the number of N is about 300).

The above dispersion may be used as it is for the following applications, but the fine resin particles may be isolated by removing the liquid medium in order to facilitate transportation and storage. For example, if the dispersion is spray-dried or freeze-dried, fine resin particles having good dispersibility in a liquid medium can be obtained.

The dispersion of the fine resin particles in a liquid medium can be used as a coating composition by itself or by blending a conventional resin component or a film-forming component or additive. In particular, the dispersion in an aqueous medium is useful as an aqueous paint, for example, a baking type topcoat paint.

The fine resin particles of the present invention have an extremely small particle size,
Moreover, the dispersibility in various liquid media is good, and a dispersion having a high concentration and high stability can be provided. In view of this property, the dispersion provides a coating film having excellent coating workability and good coating film appearance and coating film physical properties.

Hereinafter, the present invention will be described more specifically with reference to examples.
However, parts and% mean parts by weight and% by weight, unless otherwise specified.

Reference Example 1 225 parts of sodium salt of taurine, 100 parts of ethylene glycol and 200 parts of ethylene glycol monoethyl ether were charged into a flask 2 equipped with a stirrer, a condenser and a temperature control device, and the temperature was kept at 120 ° C. with stirring.
Raise to. After the contents became homogeneously dissolved, a solution consisting of 384 parts of Denacol Ex931 (Nagase Sangyo Co., Ltd. polypropylene oxide diglycidyl ether type epoxy resin, epoxy equivalent 384) and 400 parts of ethylene glycol monoethyl ether was added for 2 hours. Drop by. After the dropping, stirring and heating are continued for 20 hours to complete the reaction. The reaction solution was acidified with hydrochloric acid, the obtained solution was concentrated and dried under reduced pressure, purified by a reprecipitation method with methyl cellosolve, and reconcentrated under reduced pressure to obtain 1020 parts of a liquid residue. 99% solids.

The acid value of this solid content dropped by KOH is 110, and fluorescence X
The sulfur content by line analysis was 6.3%. This solid content is a substance having a zwitterionic group at both ends of its molecule. The resulting compound has the formula: Reference example 2 Adopting the same equipment and operation as in reference example 1, Denacol E
Instead of x931, 470 parts of Epicoat 1001 (bisphenol A diglycidyl ether type epoxy resin manufactured by Shell Chemical Co., epoxy equivalent 470) was reacted. As a result, 1212 parts of a liquid residue was obtained. 98% solids.

The acid value of this solid content by KOH dropping was 94, and the sulfur content by fluorescent X-ray analysis was 5.3%. This solid content is a substance having a zwitterionic group at both ends of its molecule. The compound obtained has the formula: Reference Example 3 53.2 parts of 1,12-dibromododecane, 40 parts of nicotinic acid and 400 parts of dimethylformamide were charged into one flask equipped with a stirrer, a condenser and a temperature control device, and reacted at 90 to 100 ° C. for 20 hours. Let After the reaction, dimethylformamide was removed under reduced pressure, acetone was added to crystallize (yield 42 parts), and recrystallized from acetone / ethanol to give 1,12-dodecanebis (3-carboxy-1).
-Viridinium) dibromide was obtained. mp219-22
0 ° C. As a result of elemental analysis, the nitrogen content was 6.74%.
Dissolve 30 parts of this dibromide in 100 parts of methanol,
Ion exchange resin (Amberlite IRA-4000H
Type), concentrated, and recrystallized from acetone to obtain a final purified product. This substance has a pyridinecarboxylic acid type zwitterionic group substantially at both ends of the molecule.
The compound obtained has the formula: Reference Example 4 Using the same apparatus as in Reference Example 3, 1,12-dodecanedithiol was produced from 100 parts of 1,12-dibromododecane and 48 parts of thiourea. Yield 80 parts. This crude dithiol 80
To 200 parts of 20% sodium hydroxide aqueous solution and stirred for a while, 100 parts of methyl iodide and 200 parts of benzene.
And 2 parts of hexadecyltrimethylammonium bromide were added, and the mixture was refluxed for 6 hours with vigorous stirring. After the reaction, the benzene layer was separated and washed with water until it became neutral,
It was dried over sodium sulfate. Benzene was distilled off and 1,12
70.8 parts of -bis (methylthio) dodecane were obtained. This was rectified and the fraction of bp 180-180.5 ° C / 2 mmHg was collected.
As a result of elemental analysis, the sulfur content was 24.56%.

30 parts of this methylthio compound and 29 parts of monobromoacetic acid were reacted at room temperature for 3 hours with stirring, and the resulting white powder was thoroughly washed with ether and 1,12-dodecanebis (5-carboxymethyl-5-methylsulfonium) dibromide 4
I got 4.1 copies. It was purified by recrystallization from acetone / methanol several times. mp129-130 ° C. As a result of elemental analysis, the sulfur content was 11.91%. 30 parts of the purified sulfonium salt was dissolved in 100 parts of methanol, treated with an ion exchange resin, concentrated and recrystallized to obtain a final purified product.

Example 1 420 parts of deionized water, 15 parts of the substance obtained in Reference Example 1 and 2.6 parts of dimethylaminoethanol were charged into one reaction vessel equipped with a stirrer, a cooling tube and a temperature control device, and the mixture was heated to 80 ° C. with stirring. The temperature was raised. After the contents are dissolved,
The temperature was maintained at 80 ° C with stirring, and an aqueous solution containing 4.8 parts of azobiscyanovaleric acid, 4.56 parts of dimethylaminoethanol and 48 parts of deionized water was charged, and then 81 parts of styrene, 81 parts of methyl methacrylate, and n-butyl acrylate. A mixed solution of 108 parts and 30 parts of 2-hydroxyethyl acrylate was added dropwise over 50 minutes. After dropping, at the same temperature, azobiscyanovaleric acid
An aqueous solution consisting of 1.2 parts, dimethylaminoethanol 1.14 parts and deionized water 12 parts was added and stirred for 60 minutes to obtain solid content 39%, pH 7.0, particle size 600Å, particle size distribution 1.1.
An emulsion of This emulsion was free from lumps, had good mechanical stability, and was stable even when left at room temperature for 3 months without forming aggregates or precipitates. The mechanical stability was determined to be good when one drop of the emulsion was rubbed between the thumb and the index finger five times and no fusion occurred.

Example 2 36 parts of styrene, 81 parts of methyl methacrylate, 108 parts of n-butyl acrylate, and 2 parts of a mixture of polymerizable monomers.
An emulsion was prepared according to the same procedure and conditions as in Example 1, except that it was prepared from 30 parts of hydroxyethyl acrylate and 45 parts of ethylene glycol dimethacrylate. The resulting emulsion has a solid content of 40%, pH
The particle size was 7.1, the particle size was 580Å, and the particle size distribution was 1.12.

As in Example 1, there were no spots, and mechanical stability and storage stability were good.

Examples 3 to 10 Examples except that a dispersant (a compound having a zwitterionic group at both ends of the molecule), deionized water, dimethylaminoethanol and a polymerizable monomer mixture were used in the proportions shown in Table 1. An emulsion was prepared according to the same procedure and conditions as in 1. The properties of the obtained emulsion are shown in Table 1.

Certificate: DMEA ... Dimethylethanolamine, ST ... Styrene, MMA ... Methyl methacrylate, n-BA ... n-Butyl acrylate, MA ... Methacrylic acid, 2-HEA ... 2
-Hydroxyethyl acrylate, EGDM ... Ethylene glycol dimethacrylate, AA ... Acrylic acid.

Reference Example 5 76 parts of ethylene glycol monobutyl ether was charged into one reaction vessel equipped with a stirrer, a cooling pipe and a temperature control device, and 45 parts of styrene and 63 parts of methyl methacrylate were charged.
Part, 2-hydroxyethyl methacrylate 48 parts, n-
61 parts of a polymerizable monomer mixed solution containing 117 parts of butyl acrylate, 27 parts of methacrylic acid, 3 parts of lauryl mercaptan and 3 parts of azobisisobutyronitrile was added, and the temperature was adjusted to 120 ° C. with stirring. After 245 parts of the polymerizable monomer mixture solution was added dropwise over 3 hours, stirring was continued for 1 hour. Further dimethyl ethanolamine 28
And 200 parts of deionized water were added to obtain an aqueous resin (acrylic resin varnish) having a solid content of 50% and a resin number average molecular weight of 6000.

Examples 11 to 17 (Preparation of pigment paste) 100 parts of the aqueous resin obtained in Reference Example 5 and 320 parts of TAIPAKE R-820 (a rutile titanium oxide pigment manufactured by Ishihara Sangyo Co., Ltd.) were placed in a 1.5-tight stainless steel container. 60 parts of deionized water was weighed, 500 ml of glass beads were added and premixed with a stirrer, and then mixed and dispersed for 2 hours with a paint conditioner to obtain a pigment paste.

(Preparation of coating composition) The materials shown in Table 2 were weighed in a stainless steel container and mixed by stirring at room temperature to obtain a coating composition.

Each of the coating compositions of Examples 11 to 17 described above was diluted with deionized water and adjusted to a viscosity of 30 seconds with a Ford cup # 4.
According to a conventional method, a steel sheet was spray coated, set for 5 minutes, and then baked at 150 ° C. for 15 minutes to obtain a three-dimensional coating film.

The pin and sag limit film pressure (coating workability), gloss value, and coating film practical performance (film pressure 40μ) of each composition are third.
Shown in the table.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shinichi Ishikura 19-17 Ikedanaka-cho, Neyagawa-shi, Osaka Japan Paint Co., Ltd. (56) References JP-A-48-18373 (JP, A)

Claims (8)

[Claims] 1. A polymer obtained by emulsion polymerization comprising (A) one or more monomers having at least one polymerizable ethylenically unsaturated group, and (B) a polymer or a long-chain alkyl chain. A number average particle diameter (n) of 100, which comprises a dispersant having a zwitterionic group substantially at both ends.
Fine resin particles having a particle size distribution (w / n) of 1.0 to 3.0 and a good dispersibility in a liquid medium. 2. The zwitterionic group has the formula:(In the formula, R₁And R_TwoAre the same or different
And may contain -O- and / or -COO-.
Alkyl group or cycloalkyl having no more than 20 carbon atoms
Group or R₁And R_TwoJoin together and combine them
Represents a nitrogen-containing heterocycle with a nitrogen atom_ThreeIs
Alkylene which may be replaced but does not exceed 8 carbon atoms
Represents a group, and Y is CO_Two , SO_Three Or PO_Four To
Represent. The use of the dispersant (B), which is a group represented by
The fine resin particles according to claim 1. 3. The zwitterionic group has the formula:(In the formula, R_FourIncludes -O- and / or -COO-
Occasionally alkyl groups or siku having no more than 20 carbon atoms
Represents a lower alkyl group, R₅May have been replaced
Represents an alkylene group having 8 or less carbon atoms, and Z is CO
_Two , SO_Three Or PO_Four Represents ) A dispersant (B) which is a group represented by
The fine resin particles according to Item 1. 4. The fine resin particle according to claim 1, wherein a dispersant (B) having zwitterionic groups present at both ends of a nonionic group is used. 5. The ratio of polymer (A) to dispersant (B) is 100:
The fine resin particles according to claim 1, which have a weight ratio of 0.1 to 10. 6. A polymerizable ethylenically unsaturated group in a liquid medium containing a dispersant having a zwitterionic group substantially at both ends of a polymer or a long alkyl chain in the presence of a polymerization initiator. Emulsion polymerization of one or more of at least one monomer to give a number average particle size (n) of 1
Characterized in that a dispersion of resin particles having a particle size distribution (w / n) of 1.0 to 3.0 is obtained, and the liquid medium is removed from the dispersion as needed to obtain fine resin particles. A method for producing fine resin particles. 7. The method for producing fine resin particles according to claim 6, wherein the liquid medium is an aqueous medium. 8. The ratio of the polymer (A) to the dispersant (B) is 100:
The method for producing fine resin particles according to claim 6, which is 0.1 to 10 (weight ratio).