JPH07102025A - Production of latex of adhesive hollow polymer particle - Google Patents

Abstract

PURPOSE:To obtain a latex of an adhesive hollow polymer particles improved in adhesiveness, opacity, printed paper gloss, white paper gloss and paper brightness by polymerizing a monomer mixture in the presence of a latex of a specified hollow polymer. CONSTITUTION:45-99wt.% aromatic vinyl monomer is copolymerized with 1-25wt.% ethylenically unsaturated carboxylic acid monomer, 5-40wt.% ethylenically unsaturated carboxylic ester monomer, and 0-49wt.% monomers copolymerizable therewith to obtain a latex of hollow polymer particles of a glass transition temperature (Tg) of 50-200 deg.C, an outside particle diameter of 50-5000nm, and a void volume of 20% or above. 1-30 pts.wt. monomer mixture comprising 30-70wt.% monomer which can give a homopolymer of a Tg of 80-200 deg.C, 30-70wt.% monomer which can give a homopolymer of a Tg of -90 to -40 deg.C, and 20wt.% or below monomers copolymerizable therewith and forming a polymer of a Tg of -80 to +50 deg.C is polymerized at 5-90 deg.C in the presence of 100 pts.wt. (in terms of the solid content) above latex.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing an adhesive hollow polymer particle latex. More specifically, it is an object of the present invention to provide a method for producing an adhesive hollow polymer particle latex that provides a coating film having excellent adhesive strength and excellent opacity, whiteness, printing gloss and white paper gloss.

[0002]

2. Description of the Related Art In the application of coated paper and paints, organic pigments are used to reduce the weight of coating films and to enhance the glossiness and whiteness of white paper. As a method for producing an organic pigment, research on a method for producing so-called hollow polymer particles having inner pores inside the particles has been actively conducted. However, most of these studies have been to increase the size of the inner pore diameter, and the hollow polymer particles obtained by these production methods have not been widely applicable as organic pigments. The present inventors have previously proposed a method for producing a latex of hollow polymer particles that can be used as an organic pigment (Japanese Patent Laid-Open No. 64-64-
1704, JP-A-3-26724). By using the hollow polymer particles obtained by these methods as an organic pigment for paper coating, it was possible to improve the opacity, whiteness, white paper gloss, etc. of the coated paper. But,
Since this hollow polymer particle is more expensive than an inorganic pigment,
At present, the applications that can be used are limited. In addition, since the hollow polymer particles have a low density, there is a problem that a large amount of binder must be used in order to increase the adhesive strength when used for coating.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a latex of adhesive hollow polymer particles which provides a coating film having excellent adhesive strength and excellent opacity, whiteness, printing gloss and white paper gloss. is there. The present inventors have conducted extensive studies to achieve the above object, in the presence of a latex of hollow polymer particles, by polymerizing a specific monomer,
It has been found that this object can be achieved, and the present invention has been completed based on this finding.

[0004]

Thus, according to the present invention, 45 to 99% by weight of an aromatic vinyl monomer, 1 to 25% by weight of an ethylenically unsaturated carboxylic acid monomer, and an ethylenically unsaturated carboxylic acid ester. 100 parts by weight (as solid content) of a latex of hollow polymer particles composed of a polymer obtained by polymerizing 5 to 40% by weight of a monomer and 0 to 54% by weight of a monomer copolymerizable therewith. Provided is a method for producing an adhesive hollow polymer particle latex, which comprises polymerizing 1 to 30 parts by weight of a monomer mixture which forms a polymer having a glass transition temperature of −80 to + 50 ° C. in the presence. .

The latex of hollow polymer particles used in the present invention is one in which the shape of the polymer particles constituting the latex is hollow.

In the latex of hollow polymer particles used in the present invention, the glass transition temperature of the hollow polymer particles constituting the latex is usually +50 to + 200 ° C., preferably +7.
When the one having a temperature of 0 to + 150 ° C. is used, the adhesive hollow polymer particles obtained by the present invention can be suitably used as an organic pigment.

In the latex of hollow polymer particles used in the present invention, the outer diameter of the polymer particles constituting the latex is
Usually, 50 to 5000 nm, preferably 100 to 200
It is 0 nm. The porosity of the polymer particles is usually 20.
% Or more, preferably 40% or more. 20% porosity
In the case of the adhesive hollow polymer particles obtained by using less than 1, the opacity and the like of the coating film will decrease.

The latex of the hollow polymer particles used in the present invention includes an aromatic vinyl monomer, an ethylenically unsaturated carboxylic acid monomer, an ethylenically unsaturated carboxylic acid ester monomer, and a monomer copolymerizable therewith. It is composed of a copolymer obtained by polymerizing a monomer.

As the aromatic vinyl monomer, styrene,
Examples include α-methylstyrene, vinyltoluene and chlorostyrene. The amount of the aromatic vinyl monomer is 45 to 99% by weight, preferably 65 to 8% by weight based on the total amount of the monomers used for obtaining the polymer constituting the latex of the hollow polymer particles.
It is 0% by weight. If it is less than 45% by weight, properties such as opacity and white paper gloss of the coating film deteriorate.

Examples of the ethylenically unsaturated carboxylic acid monomer include ethylenically unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid and crotonic acid; fumaric acid, maleic acid,
Ethylenically unsaturated polyvalent carboxylic acids such as itaconic acid and butenetricarboxylic acid; partial esterification products of ethylenically unsaturated polyvalent carboxylic acids such as monoethyl maleate and monomethyl itaconate. The amount of the ethylenically unsaturated carboxylic acid monomer is 1 to 1 of all the monomers used to obtain the polymer constituting the latex of the hollow polymer particles.
It is 25% by weight, preferably 1 to 15% by weight. When it exceeds 25% by weight, the porosity of the hollow polymer particles decreases.

Examples of the ethylenically unsaturated carboxylic acid ester monomer include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, and (meth).
N-amyl acrylate, isoamyl acrylate (meth), hexyl (meth) acrylate, ethylhexyl (meth) acrylate, octyl (meth) acrylate, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, Examples thereof include glycidyl (meth) acrylate. The amount of the ethylenically unsaturated carboxylic acid ester monomer is 5 to 40% by weight based on the total amount of the monomers used for obtaining the polymer constituting the latex of the hollow polymer particles.
It is preferably 10 to 30% by weight. If it is less than 5% by weight, the porosity of the hollow polymer particles is lowered, and if it exceeds 40% by weight, properties such as opacity and glossiness of white paper are lowered.

The monomer copolymerizable with the aromatic vinyl monomer, the ethylenically unsaturated carboxylic acid monomer and the ethylenically unsaturated carboxylic acid ester monomer is an ethylenic unsaturated monomer such as (meth) acrylonitrile. Saturated nitrile monomer; ethylenically unsaturated glycidyl ether such as allyl glycidyl ether; (meth) acrylamide, N-methylol (meth) acrylamide, N-butoxymethyl (meth)
Ethylenically unsaturated amide monomer such as acrylamide;
1,3-butadiene, isoprene, 2,3-dimethyl-
Conjugated diene monomers such as 1,3-butadiene and 1,3-pentadiene; vinyl halides such as vinyl chloride and vinylidene chloride; carboxylic acid vinyl esters such as vinyl acetate;
Vinyl pyridine etc. are mentioned. The amount of these monomers is 49% by weight or less, preferably 24% by weight or less, based on the total monomers used for obtaining the polymer constituting the latex of the hollow polymer particles.

Examples of the method for producing the latex of hollow polymer particles used in the present invention include the methods described in JP-A-60-69103, JP-A-64-1704 and JP-A-3-26724. To be Of the latexes of hollow polymer particles obtained by these production methods, a base is added to the carboxyl-modified copolymer latex to adjust the latex pH to 8 or more, and then an acid is added to adjust the latex pH to 7 or less. Obtained (JP-A-64-17)
No. 04, JP-A-3-26724)
The latex of hollow polymer particles is composed of hollow polymer particles having a high porosity and a large particle size, and the polymerization stability when polymerizing a monomer in the presence of the hollow polymer particle latex is high. Therefore, it is preferable.

The monomer mixture which is polymerized in the presence of the hollow polymer particle latex used in the present invention has a glass transition temperature of -80 to + 50 ° C., preferably -60 to +30, obtained by polymerizing the monomer mixture. It will be ℃. + 50 ° C
When it exceeds, the adhesive strength of the coating film using the adhesive hollow polymer particles as an organic pigment becomes low. On the other hand, if the temperature is lower than -80 ° C, it becomes difficult for the particle shape to become hollow, and the opacity of the coating film decreases.

The monomer mixture to be polymerized in the presence of the hollow polymer particle latex used in the present invention is usually a monomer having a homopolymer glass transition temperature of +80 to + 200 ° C., preferably +90 to + 150 ° C. And the glass transition temperature of the homopolymer is −90 to −40 ° C., preferably −90 to −
Those composed of a monomer at 50 ° C. and another copolymerizable monomer are preferable.

Specific examples of the monomer having a glass transition temperature of +80 to + 200 ° C. of the homopolymer constituting the monomer mixture are aromatics such as styrene, t-butylstyrene, chlorostyrene and α-methylstyrene. Vinyl monomers; ethylenically unsaturated carboxylic acid ester monomers such as methyl methacrylate, t-butyl methacrylate, isopropyl methacrylate and phenyl methacrylate; ethylenically unsaturated carboxylic acids such as methacrylic acid, acrylic acid and itaconic acid Acid monomers; ethylenically unsaturated carboxylic acid amide monomers such as acrylamide; ethylenically unsaturated nitrile monomers such as acrylonitrile and methacrylonitrile; and the like. Of these monomers, styrene and methyl methacrylate are preferable. The glass transition temperature of homopolymer is +
The amount of the monomer at 80 to + 200 ° C. is usually 30 to 70% by weight, preferably 40 to 60% by weight of the monomer mixture. If it exceeds 70% by weight, the adhesive strength of the coating film is lowered. If it is less than 30% by weight, the glossiness of the coating film on white paper, opacity and the like are lowered.

The homopolymer has a glass transition temperature of -90 to-.
As the monomer at 40 ° C., ethylenically unsaturated carboxylic acid ester monomers such as propyl acrylate, butyl acrylate, heptyl acrylate, 2-ethylhexyl acrylate, and 2-ethoxypropyl acrylate; 1,3- Conjugated diene monomers such as butadiene, 2-ethyl-1,3-butadiene and isoprene; and the like. Of these monomers, 1,3-butadiene and butyl acrylate are preferable. The glass transition temperature of the homopolymer is -90 to -4.
The amount of the monomer at 0 ° C. is usually 30 to 7 of the monomer mixture.
It is 0% by weight, preferably 40 to 60% by weight. When it exceeds 70% by weight, the glossiness of the coating film on white paper is reduced. If it is less than 30% by weight, the adhesive strength of the coating film is lowered.

The homopolymer has a glass transition temperature of +80 to +
The glass transition temperature of the monomer and homopolymer at 200 ° C. is −
Other monomers copolymerizable with the monomer at 90 to -40 ° C. include ethyl acrylate, methyl acrylate, t-butyl acrylate, ethyl methacrylate, butyl methacrylate, i-butyl methacrylate, Ethylenically unsaturated carboxylic acid ester monomers such as 2-hydroxyethyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, glycidyl methacrylate; carboxylic acids such as vinyl acetate Vinyl ester monomer; and the like.
The amount of these monomers is usually 30% by weight or less, preferably 20% by weight or less of the monomer mixture.

The amount of the monomer mixture is 1 to 30 parts by weight, preferably 10 to 28 parts by weight, based on 100 parts by weight of the solid content of the latex of the hollow polymer particles. If the amount is less than 1 part by weight, the binder function of the adhesive hollow polymer particles is deteriorated,
If it exceeds 30 parts by weight, the porosity of the adhesive hollow polymer particles becomes small, so that the opacity, glossiness of white paper, printing gloss, whiteness and the like of the coating film obtained by using the particles become low.

Polymerization of the monomer mixture which can give a polymer having a glass transition temperature of -80 to + 50 ° C. is carried out in the presence of a latex of hollow polymer particles. In particular,
Following the polymerization of the latex of the hollow polymer particles, the monomer mixture may be added to carry out the polymerization, or the latex of the hollow polymer particles may be separately polymerized to obtain the latex of the hollow polymer particles. The monomer mixture may be appropriately transferred to a reactor and polymerized. The method of polymerization may be any method such as emulsion polymerization method, suspension polymerization method and precipitation polymerization method. The polymerization medium may be water, an organic solvent such as alcohol or ketone, or a mixed solvent thereof.

In the polymerization of the monomer mixture, the method of adding the monomer or the polymerization auxiliary material is not particularly limited, and any method such as initial batch addition method, divided addition method and continuous addition method may be used. The addition method can also be adopted. The polymerization temperature is also not particularly limited and is usually 5 to 90.
℃.

[0022]

The latex of the adhesive hollow polymer particles obtained by the production method of the present invention is used as an organic pigment, a heat insulating agent and the like by being mixed with a coating material to obtain adhesive strength, opacity, white paper gloss, printing gloss and Since a coating film having excellent whiteness can be obtained, it can be suitably used for printing paper, thermal paper, water-based paint and the like.

[0023]

EXAMPLES The present invention will be described in more detail with reference to the following examples. The parts and% in the examples are based on weight.

The evaluation method used in this example will be described below. (Glass transition temperature) Polymer latex was cast on a glass plate with a frame and heated at 23 ° C. and 65% R.A. H. The solid is obtained by leaving it in the atmosphere of 48 hours. About this solid, a differential scanning calorimeter (DSC, manufactured by Seiko Instruments Inc .: SSC520
0) was used under the conditions of a starting temperature of -100 ° C and a heating rate of 5 ° C / min.

(Average particle outer diameter, porosity) A photograph was taken with a transmission electron microscope, 350 particles were randomly selected from the photograph, the outer diameter and inner pore diameter of the particles were measured, and the number average thereof was obtained. . The porosity was expressed as a ratio of the volume obtained from the average particle outer diameter and the average inner pore diameter, assuming that the particles are true spheres.

(Adhesive Strength) An RI tester (manufactured by Akashi Seisakusho Co., Ltd.) was used for coated paper, and solid printing was performed using a printing ink (tack value 26). Then, the peeling (picking) state of the paper surface was observed and the 5-point method was used. It was evaluated by. The higher the score, the higher the adhesive strength.

(Opacity) With respect to the coated paper, the amount of light reflected by the standard white plate and the standard black plate under the condition that a green filter (540 nm) was used using a Hunter whiteness meter (Murakami Color Research Laboratory). Was measured.

With respect to the coated paper (white paper gloss), the light reflectance was measured using a gloss meter (Murakami Color Research Laboratory: GM-26D) under the conditions of an incident angle of 75 degrees and a reflection angle of 75 degrees.

(Printing Gloss) The indigo color ink was solid-printed on the coated paper using an RI printing machine (manufactured by Akira Seisakusho Co., Ltd.), and then the light reflectance was measured in the same manner as the measurement method of white paper gloss.

(Whiteness) With respect to the coated paper, the amount of reflected light was measured using a Hunter whiteness meter (manufactured by Murakami Color Research Laboratory) under the condition that a blue filter (457 nm) was used.

Reference Example 1 To 30 parts of ion-exchanged water, 0.2 parts of sodium dodecylbenzenesulfonate, 81 parts of styrene, 12 parts of methyl methacrylate and 7 parts of methacrylic acid were added and stirred to obtain a monomer emulsion. It was Charge 200 parts of ion-exchanged water into a flask equipped with a reflux condenser, a thermometer and a separating funnel. 8
Warmed to 0 ° C. Add potassium persulfate (KP
S) 5 parts of 3% aqueous solution was added. Then, the monomer emulsion and 20 parts of a 3% aqueous solution of potassium persulfate were simultaneously added, and the addition was completed 8 hours later. After the addition was completed, the reaction was further continued for 2 hours and then cooled to 20 ° C. to obtain a carboxy-modified copolymer latex. Next, 5 parts of styrene was added to this carboxy-modified copolymer latex, and immediately after that, 44 parts of a 10% aqueous solution of potassium hydroxide was added. After the addition, the mixture was heated to 80 ° C. and stirred for 3 hours. PH at this time
Was 12.3. Then, 140 parts of a 5% aqueous methacrylic acid solution was added, and the mixture was stirred at 80 ° C. for 3 hours. The pH at this time was 5.5. Then, potassium persulfate 3%
Add 10 parts of the aqueous solution, stir at 80 ° C. for 2 hours to polymerize the residual monomer, and cool to 20 ° C. to obtain an average particle outer diameter of 500.
A latex A of hollow polymer particles having a particle size of 60 nm, a porosity of 60%, a glass transition temperature of 105 ° C. and a solid content concentration of 30% was obtained.

Reference Example 2 In the same manner as in Reference Example 1 except that the monomer used in the monomer emulsion in Reference Example 1 was changed to the formulation shown in Table 1 or 2, the particle outer diameter was 500 nm and the porosity was 59%, latex B of hollow polymer particles having a glass transition temperature of 105 ° C. and a solid content concentration of 30% and a particle outer diameter of 500 nm, a porosity of 59%, a glass transition temperature of 108 ° C. and a solid content concentration of 30%.
To obtain latex C of hollow polymer particles of

Example 1 100 parts of latex A (solid content) of the hollow polymer particles obtained in Reference Example 1 was placed in a separable flask equipped with a reflux condenser and stirred, and then 0.1 part of sodium dodecylbenzenesulfonate was added. , 8 parts of styrene, 8 parts of 1,3-butadiene, 0.02 part of t-dodecyl mercaptan and 25 parts of ion-exchanged water were added, and the mixture was heated to 80 ° C.
After reaching 80 ° C., 8 parts of a 3% aqueous solution of potassium persulfate was added, followed by stirring while maintaining the temperature for 3 hours, and finally cooling to 20 ° C. to obtain an adhesive hollow polymer. A latex of particles was obtained. The evaluation results are shown in Table 1.

Examples 2 to 6 Adhesive hollows were prepared in the same manner as in Example 1 except that the monomers used in the latex and emulsion of the hollow polymer particles in Example 1 were changed to the formulations shown in Tables 1 and 2. A latex of polymer particles was obtained. The evaluation results are shown in Tables 1 and 2.

[0035]

[Table 1]

Comparative Examples 1 to 4 Adhesive hollow polymer particles were prepared in the same manner as in Example 1 except that the monomers used in the latex and emulsion of the hollow polymer particles in Example 1 were changed to the formulations shown in Table 2. Obtained a latex. The evaluation results are shown in Table 2.

Reference Example 3 To 30 parts of ion-exchanged water, 0.2 part of sodium dodecylbenzenesulfonate, 70 parts of styrene, 25 parts of methyl methacrylate and 7 parts of methacrylic acid were added and stirred to obtain a monomer emulsion. It was Charge 200 parts of ion-exchanged water into a flask equipped with a reflux condenser, a thermometer and a separating funnel. 8
Warmed to 0 ° C. Add potassium persulfate (KP
S) 5 parts of 3% aqueous solution was added. Then, the monomer emulsion and 20 parts of a 3% aqueous solution of potassium persulfate were simultaneously added, and the addition was completed 8 hours later. After the addition was completed, the reaction was further continued for 2 hours and then cooled to 20 ° C. to obtain a carboxy-modified copolymer latex.

Comparative Example 5 Adhesive polymer particles were prepared in the same manner as in Example 1 except that the hollow polymer particle latex A used in Example 1 was replaced by the carboxy-modified copolymer latex obtained in Reference Example 4. Obtained a latex. The evaluation results are shown in Table 2.

Reference Example 4 10 parts latex (solid content) of the adhesive (hollow) polymer particles obtained in the above Examples and Comparative Examples, 90 parts Kaolin clay (UW90 manufactured by Engelhard Co.), dispersant (Toa) Synthetic Co., Ltd .: Allo-T-40) 0.1 part, sodium hydroxide 0.05 part, oxidized starch 3 parts and carboxy-modified conjugated diene latex (manufactured by Zeon Corporation: Nipol).
(e407F, solid content) 8 parts were mixed and stirred to obtain a paper coating composition having a solid content concentration of 65%. Each of these paper coating compositions was coated on high-quality paper at a coating amount of 15 g / m ² per side.
And apply hot air at 140 ° C for 30
Dried for 20 seconds at 65 ° C. H. It was left overnight in a constant temperature and humidity room. After that, temperature 50 ℃, linear pressure 100 kg /
The coated paper was obtained by performing super calendar treatment twice under the condition of cm. Table 2 shows the evaluation results of these coated papers.

[0040]

[Table 2]

It can be seen from Tables 1 and 2 that the method of the present invention gives a latex of adhesive hollow polymer particles which gives a coating having excellent adhesive strength, opacity, printing gloss, white paper gloss and whiteness. .

Claims (1)

[Claims] 1. 45 to 99% by weight of an aromatic vinyl monomer,
Obtained by polymerizing 1 to 25% by weight of an ethylenically unsaturated carboxylic acid monomer, 5 to 40% by weight of an ethylenically unsaturated carboxylic acid ester monomer, and 0 to 49% by weight of a monomer copolymerizable therewith. 1 to 30 parts by weight of a monomer mixture which forms a polymer having a glass transition temperature of −80 to + 50 ° C. in the presence of 100 parts by weight (in terms of solid content) of a latex of hollow polymer particles composed of a polymer to be obtained. A method for producing an adhesive hollow polymer particle latex, which comprises polymerizing.