JP3154477B2 - Fine particle aggregate emulsion and method for producing the same - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a fine particle aggregate emulsion useful as an additive for a coating agent used for paints, paper coatings, information recording papers, and the like, and a method for producing the same.

[Conventional technology]

In recent years, various particulate polymers have been studied as additives for coating agents for the purpose of organic pigment substances.

The most commonly used one has a particle size of 0.
It is a uniform solid emulsion polymerized polystyrene particle of 2 to 0.5 μm. For example, in the method described in JP-A-59-59741, an unsaturated carboxylic acid and a vinyl monomer are copolymerized in the presence of an anionic surfactant and / or a nonionic surfactant, and the particle size is reduced. An example in which 90% or more of a copolymer emulsion having a particle size of 0.20 to 0.28 μ is manufactured and used for applications such as paper coating or paint is exemplified. Since the organic pigment obtained by this method has a uniform interior of the particles, sufficient concealment and whiteness cannot be obtained, and practical advantages cannot be recognized unless used in large amounts.

In recent years, organic pigments having small pores have been proposed from the above-mentioned uniform and solid type for the purpose of further improving opacity and whiteness (US Pat. No. 3,152,280). That is, an emulsion obtained by adding at least one kind of monoethylenically unsaturated monomer or a monomer forming a pod polymer to a polymer dispersion obtained by copolymerizing at least 5% of a carboxylic acid monomer as a core particle, and emulsion-polymerizing the emulsion. Is a method for producing an aqueous dispersion in which microvoids are formed by neutralizing and swelling the core polymer with an aqueous volatile base.

When an organic pigment according to this method is used in a paint or a composition for coating paper, the pores are broken by the method of use, although the hiding power and whiteness are improved compared to a uniform, solid type organic pigment,
There is a drawback that the originally intended hiding power and whiteness are impaired. The pores may be damaged due to freezing, destruction by a certain solvent used in paint formulation, or destruction by heating, and can be used only in a limited form in terms of formulation or use.

[Problems to be solved by the invention]

The present invention, when used for paints, paper-coated information recording paper, etc., satisfies physical properties such as hiding power, whiteness, gloss, etc., and at the same time, there are few restrictions on compounding or use, and fine particle aggregates that can be used stably A primary purpose is to provide a body emulsion.

[Means for solving the problem]

The present inventors have proposed an organic polymer having an excellent particle shape in which a two-component heterogeneous polymer is non-uniformly present in one particle and one of which is present as an aggregate of fine particles in the particle. The present inventors have found that they have suitability as pigments, and have reached the present invention.

That is, the present invention provides an unsaturated carboxylic acid of 1 to 50% by weight.
And at least a partially neutralized copolymer (a) consisting of 99 to 50% by weight of a vinyl monomer (excluding a fluororesin) copolymerizable therewith, 0.5 to 90 parts by weight, Heterogeneous polymer (b) 9 obtained by polymerizing copolymer (a) and a vinyl monomer having a composition having a different polymerization component and / or component ratio.
A fine particle aggregate emulsion comprising 9.5 to 10 parts by weight, wherein the copolymer (b) has a diameter of 0.05 to 0.5 μm.
Exist as particles, and the particle diameter of the aggregate particles is 0.2 to
This is a fine particle aggregate emulsion having a size of 3.0 μm.

In the particle emulsion having such a structure, as a first step, 1 to 50% by weight of an unsaturated carboxylic acid and a vinyl monomer copolymerizable therewith (excluding a fluorine-containing resin)
Emulsion polymerization of 99 to 50% by weight was carried out, followed by neutralization with 0.3 to 3.0 molar equivalents of an alkaline substance with respect to the carboxylic acid in the copolymer emulsion. As a second step, the neutralized emulsion was used as seed particles to form a copolymer. Polymer (a) and polymerization component and / or
Or a vinyl-based monomer having a composition having a different component ratio, based on a solid content of 0.5 to 90 parts by weight of the neutralized emulsion, 99.5 to 1
It is obtained by emulsion polymerization with addition of 0 parts by weight.

In the neutralization, the unsaturated carboxylic acid copolymer needs to be swollen with an alkali, and under the swelling of the particles, a vinyl monomer different from (a) containing a crosslinkable monomer is used if necessary. In addition, particles that are aggregates of fine particles are obtained only by emulsion polymerization.

The unsaturated carboxylic acids used in the present invention include, for example, acrylic acid, methacrylic acid, unsaturated monobasic acids such as crotonic acid, itaconic acid, fumaric acid, unsaturated dibasic acids such as maleic acid and monoesters thereof. One or more selected ones are preferable, and acrylic acid and methacrylic acid are particularly preferable.

The amount of the unsaturated carboxylic acid to be used is 1 to 50 parts by weight, preferably 2 to 20 parts by weight, more preferably 5 to 15 parts by weight based on all the monomer components in the copolymer (a). If the amount is less than 1 part by weight, the emulsion particles are less swelled by the alkali, and particles which are an aggregate of fine particles cannot be obtained. If the amount exceeds 50 parts by weight, water resistance and alkali resistance become poor.

The vinyl monomer copolymerizable with the unsaturated carboxylic acid having a polymer composition of the copolymer (a) is, for example, styrene,
Aromatic vinyl compounds such as α-methylstyrene and vinyltoluene; (meth) methyl such as methyl (meth) acrylate, ethyl (meth) acrylate, and butyl (meth) acrylate
Vinyl esters such as acrylates, vinyl acetate and vinyl pyropionate, vinyl cyanide compounds such as (meth) acrylonitrile, and vinyl halide compounds such as vinyl chloride and vinylidene chloride are used.
In addition, as the functional group monomer, other than the unsaturated carboxylic acid, (meth) acrylamide or N-methylol (meth) acrylamide, 2-hydroxyethyl (meth) acrylate, glycidyl (meth) acrylate, or the like is used as necessary. You.

The copolymer (a) needs to swell as a whole during neutralization. This indicates that the glass transition temperature of the copolymer (a) is 90
° C. or less, especially the above monomer is selected to be 70 ° C. or less,
It is preferable to combine them.

In order to adjust the degree of swelling of the emulsion particles by alkali neutralization, a crosslinkable monomer described below can be copolymerized as necessary. The amount of the crosslinkable monomer used is 20 parts by weight or less, preferably 10 parts by weight or less, and the appropriate amount used varies depending on the type of unsaturated carboxylic acid, the amount used, the type of the vinyl monomer, and the like. .

Examples of the kind of the alkaline substance used for swelling the emulsion particles include inorganic alkaline substances such as potassium hydroxide, sodium, calcium, and sodium silicate, volatile alkaline substances such as ammonia, dimethylethanolamine, triethylamine, and triethanolamine. And an organic alkaline substance such as morpholine.

The degree of neutralization was 0,0 relative to the unsaturated carboxylic acid used in the polymerization.
It is preferably 3 to 3.0 molar equivalents, more preferably 0.5 to 2.0 molar equivalents. If it is less than 0.3 molar equivalent, the degree of swelling with the alkaline substance is small, and the desired particles cannot be obtained. or,
If it exceeds 3.0 molar equivalents, the pH of the resulting organic pigment is too high, resulting in poor water resistance and the like, which is not practical.

Preparation of the copolymer (a) serving as seed particles is performed by a usual emulsion polymerization method. As the surfactant used, an anionic surfactant and a nonionic surfactant are used alone or in combination.

Examples of the anionic surfactant include sodium alkylbenzenesulfonate, sodium alkylsulfate, sodium dialkylsulfonesuccinate, and formalin naphthalene sulfonate condensate.
Examples of the nonionic surfactant include polyoxyethylene alkyl ether, polyoxyethylene alkyl phenol ether, ethylene oxide-propylene oxide block copolymer, and sorbitan fatty acid ester.

The amount of the surfactant used is not particularly limited, but is usually 0.1 to 10 parts by weight based on 100 parts by weight of the total monomers.

The polymerization initiator may be any one used in ordinary emulsion polymerization.Examples include persulfates such as potassium persulfate, sodium, and ammonium, organic peroxides such as benzoyl hydroperoxide, and azobis. And azo compounds such as isobutyronitrile. If necessary, it can be used as a redox initiator in combination with a reducing agent.

In producing the seed particles, the polymerization initiator described above,
In the presence of a surfactant, polymerization is carried out by dropping various monomers at once, dividedly or continuously. In this case, the polymerization is usually carried out at a polymerization temperature of 20 to 90 ° C. under a nitrogen purge.

The copolymer emulsion thus obtained is neutralized with the above-mentioned alkaline substance, and as a second step, the neutralizing emulsion is used as seed particles and a crosslinkable monomer is required as a different component from the copolymer (a). A vinyl-containing monomer is added and emulsion polymerization is carried out to obtain an aggregate emulsion in which particles of the heterogeneous polymer (b) are aggregated in one particle. At this time, the copolymer (a) used as seed particles is 0.5 to 90 parts by weight, preferably 1 to 60 parts by weight, and more preferably 3 to 40 parts by weight. When the amount is 0.5 part by weight or less, the copolymer (a) is used as the second step.
When a vinyl monomer having a composition different from that described above is added and emulsion polymerization is performed, new particles are likely to be generated separately from the seed particles, and the particle shape intended for the present invention cannot be obtained.

When the content is 90 parts by weight or more, the particle size of the heterogeneous polymer (b) in the target fine particle aggregate becomes small, and substantially,
No particles of the invention are obtained.

The crosslinkable monomer used as necessary is a monomer having two or more polymerizable unsaturated bonds in one molecule,
For example, divinylbenzene, ethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, ethylene glycol diacrylate, 1,3-butylene glycol dimethacrylate, diallyl phthalate and the like.

When the crosslinkable monomer is used, the amount is 20 parts by weight or less, preferably 10 parts by weight or less based on the vinyl monomer. The use of a crosslinkable monomer improves blocking resistance, heat resistance, and solvent resistance. However, if it exceeds 20 parts by weight, polymerization will not be successful, and a large amount of aggregates will be generated.

Vinyl monomers include, for example, styrene, α-methylstyrene, aromatic vinyl compounds such as vinyltoluene,
(Meth) acrylates such as methyl (meth) acrylate, ethyl (meth) acrylate and butyl (meth) acrylate; vinyl esters such as vinyl acetate and vinyl propionate; and vinyl cyanes such as (meth) acrylonitrile Compounds, vinyl halide compounds such as vinyl chloride and vinylidene chloride, and conjugated diene compounds such as butadiene.

For the purpose of imparting various stability such as mechanical stability and miscibility of the emulsion, as a functional group monomer, in addition to the unsaturated carboxylic acid used in the copolymer (a), (meth) acrylamide, N -One or a combination of functional group monomers used in ordinary emulsion polymerization, such as methylol (meth) acrylamide, 2hydroxyethyl (meth) acrylate, and glycidyl (meth) acrylate, are used.

The glass transition point of the heteropolymer (b) obtained by combining the above monomers used in the second step is preferably 50 ° C. or higher, more preferably 70 ° C. or higher. In this sense, it is preferable to use styrene, methyl methacrylate, and acrylonitrile alone or in combination with another monomer.

The composition of the copolymer (a) obtained by copolymerizing an unsaturated carboxylic acid and the different polymer (b) containing a crosslinkable monomer as required must be different from each other. Cannot be obtained, and when used as an organic pigment, the whiteness, the deteriorating power, and the like cannot be sufficiently obtained. As a preferable composition, the refractive index of the unsaturated carboxylic acid copolymer (a) is different from the refractive index of the heteropolymer (b) containing a crosslinkable monomer as required, and the compatibility between the polymers is low. Those which are poor and are easily phase-separated are preferable.

As the polymerization method of the second step, the copolymer emulsion obtained by copolymerizing the unsaturated carboxylic acid of the first step is neutralized and swelled with an alkaline substance, and the vinyl monomer containing a crosslinkable monomer is used as it is, if necessary. Or by emulsifying and subsequently adding all at once, dividedly or continuously. At that time, it is necessary to select polymerization conditions that do not produce new particles.

The particulate polymer thus obtained is composed of a copolymer (a) composed of an unsaturated carboxylic acid and a vinyl monomer copolymerizable therewith, and a crosslinkable monomer having a different composition. Consisting of a heterogeneous polymer (b) containing
(B) is non-uniformly present in one particle, the particle diameter of the mixed particles of (a) and (b) is 0.2 to 3.0 μm, and the particle diameter of the heteropolymer (b) in the particle is 0.05 It is an aggregate of 0.5 μm fine particles.

If the particle diameter of the mixed particles of (a) and (b) is less than 02μ, sufficient hiding power and whiteness cannot be obtained, and if it exceeds 3.0μ, gloss and printing gloss in addition to the hiding power and whiteness will not be obtained. Will be insufficient.
If the particle diameter of the heteropolymer (b) in the particles is less than 0.05 μm, the hiding power and whiteness are insufficient, and if it exceeds 0.5 μm, an aggregate of fine particles cannot be stably obtained.

The particle diameter of the heterogeneous polymer (b) in the particles is the copolymer (a)
Can be controlled by the amount of the carboxylic acid in the seed particles comprising and the degree of neutralization thereof, the amount of the initiator during the polymerization, the degree of crosslinking of the heteropolymer (b), and the like. For example, if the amount of carboxylic acid in the seed particles is reduced, the particle size of the heteropolymer (b) increases. The aggregate particles themselves can be easily controlled by changing the particle diameter and the amount of the seed particles.

The form of the copolymer (a) is not particularly limited.
For example, when the amount of the copolymer (a) is larger than that of the heterogeneous polymer (b), the copolymer (a) exists as a continuous layer, and the heterogeneous polymer (b) is contained in the continuous phase. Exists as
When the amount of the copolymer (a) is smaller than that of the heteropolymer (b), it is interposed between the particles of the heteropolymer (b),
This is a preferred form.

The thus obtained fine particle aggregate emulsion is different from the conventional method for preparing spinous particles by phase separation (for example, Polymer Journal, 33 , 575 (1976)). It is very different from the one that has been polymerized into confetti and has the characteristic that the whole particle is an aggregate of fine particles.

Further, as a method of forming an aggregate of fine particles, a method of blending particles having opposite charges and preparing an aggregate emulsion by a secondary aggregation method such as a salting-out method is known. However, it is difficult to form a uniform aggregate having a wide particle size distribution by this method. The fine particle aggregate emulsion of the present method has a feature that the particle size distribution is narrow and sharp due to the characteristics of the polymerization method.

〔Example〕

Hereinafter, specific examples of the present invention will be described.
In addition, all parts and% show a weight part or weight%.

Example 1 In a separable flask equipped with a stirrer, a thermometer and a reflux condenser, 100 parts of water and 0.05 part of sodium lauryl sulfate were charged as a first step, and the mixture was stirred at 70 ° C while purging with nitrogen.
Raise the temperature until While maintaining the internal temperature at 70 ° C., 0.8 parts of potassium persulfate was added as a polymerization initiator, and after confirming that it was dissolved, a mixed monomer of 4 parts of methyl methacrylate, 4 parts of butyl acrylate, and 2 parts of methacrylic acid was charged. Allowed to react for hours.

After the reaction, 1.6 parts (about 1.1 molar equivalent) of 28% aqueous ammonia is added to the obtained copolymer emulsion, and the mixture is stirred well to neutralize and swell to obtain seed particles.

Separately, 50 parts of water, 0.5 part of sodium lauryl sulfate, 85 parts of styrene and 5 parts of divinylbenzene are added and stirred well to prepare a second-stage monomer emulsion. As a second step, the vinyl monomer emulsion is continuously injected into the above-described neutralized and swollen seed particles over 4 hours to carry out a reaction.
Allow time to mature.

The obtained emulsion has a solid content of about 40% and a viscosity of 65 cps (B
M-type viscometer rotor No.1, rotation speed 60 rpm, temperature 25 ° C), pH
8.5. When the particle diameter was measured by an electron microscope, the average particle diameter was 0.9 μm, and the particle diameter of the component (b) of the fine particle aggregate was 0.1 to 0.3 μm.

Examples 2 to 7 Amount of surfactant, degree of neutralization, difference in alkaline substance, copolymer (a) / heteropolymer (b) ratio, monomer composition, crosslinkable monomer, functional group monomer The polymerization was performed according to the method of Example 1 with the composition shown in Table 1 to obtain a fine particle aggregate emulsion.

Comparative Example 1 As a first step, polymerization was carried out with exactly the same composition as the vinyl monomer composition shown in Example 1 to obtain a copolymer emulsion. An unneutralized state without neutralization swelling with an alkaline substance is used as it is as a seed particle, and the monomer composition of the second stage is added in exactly the same manner as in Example 1 with the same composition. Polymerization was performed.

The resulting emulsion has a pH of 2.2, a solids content of about 40%,
Although the viscosity was 10 cps and the average particle size was 0.9 μm, the particles were not aggregates of fine particles as in Example 1 but were spinous particles having irregularities on the surface.

Comparative Examples 2 to 4 Comparative Example 2 in which the unsaturated carboxylic acid monomer of Example 1 was not used at all was used as Comparative Example 2, and the second-stage reaction was performed at the first-stage monomer composition ratio of Example 6, and the same reaction was performed. Comparative Example 3 was obtained by polymerizing with the composition, and Comparative Example 4 was used in which the amount of sodium lauryl sulfate in the first stage was significantly increased in order to reduce the particle size in exactly the same manner as in Example 1. did. Table 1 shows the compositions of Comparative Examples 2 to 4.

Application Example 1 (Application for Paints) Paints were formulated by replacing the fine particle aggregate emulsions of Examples 1 to 7 and Comparative Examples 1 to 4 with a part of rutile type titanium dioxide as an organic pigment. In this case, an acrylic emulsion Marmatex E-208 having a resin solid content of 45% was used as a vehicle for coating.

 The paint formulation is as follows.

Water 45.0 parts 25% aqueous solution of Tamol 731 (dispersant) 12.2 [manufactured by Rohm and Haas Co., Ltd.] Ethylene glycol 40.0 2-amino 2-methylpropanol 3.0 Nopco DF-122NS (antifoaming agent) 0.8 [manufactured by San Nopco Co., Ltd.] Rutile type titanium dioxide 164.5 Fine particle aggregate emulsion (40%) 102.8 Armatex E-208 676.0 [Mitsui Toatsu Chemical Co., Ltd.] 1 part ethylene glycol monobutyl ether and CS-12
[Chisso Corporation] 40.0 (Coating aid) 2 parts mixed solvent 1 part hydroxyethyl cellulose 1 part and propylene glycol 10 mixed liquid 12.4 Paint solids 46.9% Pigment weight% in paint solids 40.0% Paint viscosity 70-80 KU The paint was prepared using water, Tamol 731, ethylene glycol, 2-amino 2-methylpropanol, Nopco DF-12
2NS, after sufficiently dispersing rutile-type titanium dioxide with a pigment disperser, adding the fine particle aggregated emulsions prepared in Examples and Comparative Examples, Almatex E-208, butyl cellosolve / Texanol, and hydroxyethyl cellulose / propylene glycol, followed by stirring. The paint was adjusted to 70-80 KU with a viscometer.

The obtained paint was applied to a slate plate so that the dry film thickness became about 40 μm, and the performance was evaluated one week after drying at room temperature.

The opacity was measured using an opacity test paper manufactured by Nippon Test Panel Kogyo Co., Ltd. with an applicator so that the dry film thickness became 75μ, and after one week drying at room temperature, the reflection was 45 ゜ / 0 ゜. Calculated from the ratio of the rates.

 Table 2 shows the results.

Measurement method Gloss Measured at an angle of 60 ° with a gloss meter manufactured by Suga Test Instruments Co., Ltd.

Hidden power Measured according to JIS-K-5663.

Water resistance Measured according to JIS-K-563, and judged that there was no abnormality such as blistering and whitening as "O".

Alkali resistance Same as above. Weather resistance No abnormality such as blistering, whitening, and decrease in gloss after 500 hours of irradiation with a weather meter was judged to be good.

Washing resistance Measured according to JIS K-5661.

If the film did not peel off after 2000 times or more, it was judged as good.

When peeling of the coating film occurs after 1,000 to 2,000 times, it is judged as Δ.

Good adhesion Good adhesion by cross-cut peeling
Is determined.

 If the cut part slightly peeled off, it was judged as △.

Application Example 2 Application for Paper Coating Performance evaluation was performed when the fine particle aggregate emulsions obtained in Examples 1 to 7 and Comparative Examples 1 to 4 were used as an organic pigment or an organic filler of a coating agent for paper coating. Was.

 The composition and evaluation method are shown below.

Formulation UW-90 [manufactured by EMC Corporation] 90 parts Pigment or filler 10 Aron T-40 [manufactured by Toagosei Chemical Industry Co., Ltd.] 0.09 (dispersant) MS-4600 [manufactured by Nippon Shokuhin Kogyo] 3 Polylac 755 [manufactured by Mitsui Toatsu Chemical Co., Ltd.] 12 Coating liquid solid content 62% To prepare the coating liquid, add Aron T-40 with 40% solid content as a dispersant to water, and use kaolin mixer to make kaolin. clay
UW-90 is sufficiently dispersed, and the above-mentioned copolymer emulsion is added to this as an organic pigment. For comparison, titanium dioxide paste having a solid content of 62% as an inorganic pigment [Dainichi Seika Co., Ltd.
Manufacture] Light calcium carbonate slurry TP-222HS (manufactured by Okutama Kogyo Co., Ltd.) having a solid content of 60% was used as an inorganic filler. As a binder, phosphoric acid-esterified starch MS-4600 and Polylac 755 having a solid content of 50% were added to prepare a coating liquid.

The above coating liquid is used as a dry coating amount with an applicator,
As of about 14~15g / m ² was applied to wood free paper, drying conditions of 120
The coating was dried at 20 ° C. for 20 seconds and passed twice with a calender roll under the conditions of a roll temperature of 60 ° C., a linear pressure of 100 kg / cm, and a speed of 10 m / min to obtain a coating liquid, and its performance was evaluated.

 Table 3 shows the results.

Evaluation method Color viscosity BM type viscometer 60rpm No.4 rotor White paper gloss JIS P-8142 Measured at 75% reflectance.

Printing gloss New Bright Indigo manufactured by Toyo Ink Co., Ltd.
Printed with RI printing tester using 4cc. After drying JIS P-8142
Measured at 75 ゜ reflectance.

Whiteness Measured by JIS P-8123 Hunter Whiteness Meter.

Opacity Measured according to JIS P-8138.

Dry pick test with RI printing test machine 10 points perfect score method Wet topic RI print test machine test 10 points perfect score method [Effect] Due to its morphological characteristics, the fine particle aggregate emulsion of the present invention is excellent in hiding power, whiteness, gloss, water resistance and the like when used for pigments and fillers of paints or paper coating agents, for example. In addition, there are few limiting conditions at the time of compounding or use, and stable use is possible. In such applications, part or all of titanium dioxide, kaolin clay and calcium carbonate can be substituted.

In addition, weight reduction, blocking properties, hardness, wear resistance,
It has an effect of improving heat resistance and the like, and can be used as an additive for various compounds and used for paper, metal, alkaline materials, plastics, fibers, cloths, and the like.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C08L 33/00 C08F 2/22 C08F 2/44 D21H 21/14

Claims (2)

(57) [Claims] 1. An unsaturated carboxylic acid of 1 to 50% by weight and at least a part of 99 to 50% by weight of a vinyl monomer copolymerizable therewith (excluding a fluorine-containing resin) are neutralized. 0.5 to 90 parts by weight of the copolymer (a) and the copolymer (a)
And a polymer component and / or a heterogeneous polymer (b) obtained by polymerizing a vinyl monomer having a composition having a different component ratio, and a fine particle aggregate emulsion comprising 99.5 to 10 parts by weight,
The copolymer (b) is a fine particle aggregate emulsion in which particles having a diameter of 0.05 to 0.5 μm are present, and the particle size of the aggregate particles is 0.2 to 3.0 μm. 2. In the first step, 1 to 50% by weight of an unsaturated carboxylic acid and 99 to 50% by weight of a vinyl monomer copolymerizable therewith (excluding a fluorine-containing resin) are emulsion-polymerized. 0.3 to the carboxylic acid in this copolymer emulsion
Neutralization with an alkaline substance of about 3.0 molar equivalents, and as a second step, using the above neutralized emulsion as seed particles, a vinyl monomer having a composition different from the copolymer (a) and a polymerization component and / or a component ratio thereof. Solid content of the neutralized emulsion 0.5 to 90
The method for producing a fine particle aggregate emulsion according to claim 1, wherein 99.5 to 10 parts by weight is added to part by weight and emulsion polymerization is performed.