JPH01144429A - Production of colored microsphere - Google Patents

Abstract

PURPOSE:To obtain a colored microsphere uniformly colored in deep color without lowering the physical strength, having excellent solvent resistance and useful as a marking material, carrier for diagnosis, etc., by treating a polymeric microsphere with an acid before dyeing. CONSTITUTION:A polymeric microsphere produced by polymerizing a monomer containing an ethylenic unsaturated group is treated with an acid such as concentrated sulfuric acid preferably under an acid treatment condition characterized by a temperature of room temperature -200 deg.C and a bath ratio of 1:2-1:50. The treated microsphere is dyed with preferably a basic dye such as anthraquinone dye. The above monomer containing ethylenic unsaturated group and constituting the polymeric microsphere is preferably incorporated with >=10wt.% (based on the whole monomer) of a monomer having >=2 ethylenic unsaturated groups [e.g., tetramethylolmethane tetra(meth)acrylate].

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for producing colored microspheres useful for various labeling materials, standard particles, diagnostic carriers, spacers for liquid crystal display elements, and the like.

(Prior art) As a method for obtaining colored microspheres, the following (1) to
The method shown in (4) has been proposed.

(1) A method of producing colored microspheres by dispersing a coloring agent such as a pigment in a monomer and then polymerizing the mixture.

(2) A method in which an oil-soluble dye is dispersed or dissolved in a monomer and then this mixture is polymerized.

(3) A method of copolymerizing a so-called reactive dye in which a polymerizable unsaturated group is introduced into the dye molecule.

(4) A method of producing uncolored microspheres and then dyeing the microspheres with a commercially available dye.

(Problems to be Solved by the Invention) However, the method according to (1) above has the disadvantage that it is difficult to uniformly disperse the colorant in the monomer, resulting in uncolored transparent particles. Furthermore, in the method of mixing this pigment into the resin, the hiding power is insufficient, so it is necessary to add a large amount of the pigment.

Therefore, the strength of the obtained colored microspheres is low (and the polymerization rate is slow).

In the method (2) above, the obtained colored microspheres have poor solvent resistance. In addition, there are drawbacks such as the dye may be discolored by the polymerization catalyst, and the dye may not polymerize because it has a polymerization inhibiting effect.

Since the method according to (3) above uses a reactive dye as a starting material, it is limited by the type of raw material, and
The disadvantage is that the degree of polymerization does not increase.

The method according to (4) above has the disadvantage that it is not possible to obtain colored microspheres that are dyed in a deep color, and that when the colored microspheres are treated with a solvent, the dye tends to separate from the surface of the microspheres (resistant to (poor solvent properties).

The present invention solves the above-mentioned drawbacks, and its purpose is to:
Coloring that can be uniformly and darkly colored, does not reduce the physical strength of the microspheres, has excellent solvent resistance, is not limited to reactive dyes as a starting material, and can increase the degree of polymerization. An object of the present invention is to provide a method for manufacturing microspheres.

(Means for Solving the Problems) The method for producing colored microspheres of the present invention involves treating polymer microspheres obtained by polymerizing a monomer having an ethylenically unsaturated group with an acid, and then treating the polymer microspheres with an acid. It is characterized by staining polymeric microspheres treated with acid, thereby achieving the above object.

The present invention will be explained in detail below.

The monomer having an ethylenically unsaturated group is composed only of a monomer having two or more ethylenically unsaturated groups, or composed only of a monomer having one ethylenically unsaturated group. Alternatively, it can be composed of a monomer having two or more ethylenically unsaturated groups and a monomer having one ethylenically unsaturated group copolymerizable therewith. In particular, the monomer having two or more ethylenically unsaturated groups is
It is preferable to use at least 10% by weight, especially at least 10% by weight. When the amount of the monomer having two or more ethylenically unsaturated groups added is less than 5% by weight based on the total amount of the monomer having two or more ethylenically unsaturated groups, the resulting polymer microspheres The hardness is low, and polymer microspheres may not be dyed in a deep color.

Examples of the monomer having two or more ethylenically unsaturated groups include the monomers shown in (1) to (4) below.

■X methylol alkyl (meth)acrylate (however,
X and y are integers that satisfy the condition of X≧y≧2). Specifically, tetramethylolmethanetetra(meth)acrylate, tetramethylolmethanetri(meth)acrylate, tetramethylolmethanedi(meth)acrylate, trimethylolpropanetri(meth)acrylate,
dipentaerythritol hexa(meth)acrylate,
Examples include dipentaerythritol penta(meth)acrylate and glycerol tri(di)(meth)acrylate.

■Polyoxyalkylene glycol di(meth)acrylate. Specifically, polyethylene glycol di(meth)
Examples include acrylate, polypropylene glycol di(meth)acrylate, etc.

■Triaryl(iso)cyanurate, triaryltrimelite, etc.

■Divinylbenzene, diaryl phthalate, diarylacrylamide, etc.

Examples of monomers having one ethylenically unsaturated group that can be copolymerized with the above-mentioned monomers having two or more ethylenically unsaturated groups include styrene, vinyltoluene, acrylonitrile, and alkyl (meth)acrylates. Esters, vinyl esters, (meth)acrylic acid, hydroxyalkyl (meth)acrylate, (meth)acrylamide,
Examples include N-methylol (meth)acrylamide and NN-dimethylaminopropylacrylamide.

Polymer microspheres can be produced by polymerizing each of the above monomers in the presence of a radical catalyst. This polymerization is preferably carried out at a temperature below the boiling point of the dispersion medium and each monomer. As the radical catalyst that can be used, organic peroxides and radical-generating catalysts in general such as azo compound rings are preferably used. Examples of the organic peroxide include benzoyl peroxide, lauroyl peroxide, di-t-butyl peroxide, and the like. As an azo compound, for example, 2.2”
Examples include 13 azobisisobutyronitrile, 2.2'f3 azobis(2,4 dimethylvaleronitrile), and the like.

Next, the polymer microspheres thus obtained are treated with acid under predetermined treatment conditions. Acid treatment conditions range from room temperature to
It can be carried out at 200°C and at a bath ratio of 1:2 to 1:50. Examples of acid treatment agents include concentrated sulfuric acid, fuming sulfuric acid,
Examples include sulfur trioxide, sulfite, sulfites, hydrogen sulfite, sulfonyl chloride, chlorosulfuric acid, fluorosulfuric acid, and aminosulfonic acid, and at least one selected from these can be used.

By treating the polymer microspheres with acid in this way, the acid causes an addition reaction with the unreacted ethylenically unsaturated groups remaining in the polymer microspheres, and/or a substitution reaction with the acid on the polymer microspheres. As a result, the acid becomes chemically bonded to the polymer microspheres. In particular, by producing polymer microspheres using a large amount of a monomer having two or more ethylenically unsaturated groups, the above acid can be added to the ethylenically unsaturated groups remaining in the polymer microspheres using sulfonic acid. As an ester, it can be reacted under relatively mild processing conditions. Furthermore, when polymer microspheres are produced using a monomer having an aromatic nucleus, sulfonic acid groups can be introduced by a sulfonation reaction of the aromatic nucleus of the polymer microspheres.

Next, the polymer microspheres treated with acid as described above are dyed. The dyeing conditions include a dye concentration of 0.5 to 5.
Adjust the staining solution to pH 2-6 with Shikage%, acetic acid vinegar and acid soda.
Adjust the bath ratio l:30~1:lO1 treatment temperature 60~1
The treatment can be carried out at 20° C. for a treatment time of 30 minutes to 15 hours. As the dye used, for example, a basic dye that can chemically bond with the acid bonded to the polymer microspheres is preferably used. This basic dye is primarily a hydrochloride of an aromatic base containing a chromophore. As basic groups, amino group (-Nl, alkylamino group (-N (CH3)z)
etc. can be included. It does not contain acidic groups and the dye ions become cations in an aqueous solution. in particular,
triphenylmethane type, anthraquinone type, azo type,
Examples include methine type and oxazine type.

Through this dyeing process, the basic dye is ionically bonded to the sulfonic acid groups in the polymer microspheres. Thereafter, colored microspheres are obtained by filtering and washing. This operation removes residual dye and inorganic salts produced as by-products of the dyeing process. Therefore, colored microspheres can be obtained that are pure and do not contain any impurities as well as alkali metals.

The colored microspheres obtained in this way can be used, for example, as a marker material,
Suitable for use as standard particles, artificial carriers for clinical diagnosis, spacers for liquid crystal display devices, etc.

(Example) The present invention will be explained below based on examples.

In a 52 separable flask equipped with a stirrer and a reflux condenser, a 2.52 g solution of 5% polyvinyl alcohol was prepared, and 625 g of divinylbenzene was added thereto.

dipentaerythritol hexaacrylate 6258,
A monomer solution in which 18.8 g of benzoyl peroxide was uniformly dissolved and mixed was charged and heated to 80°C with stirring.
The temperature was raised to 95° C. and the polymerization reaction was carried out for 10 hours, and the temperature was further raised to 95° C. and the polymerization reaction was carried out for 1 hour. Next, the mother liquor was separated and washed to obtain crosslinked polymer microspheres of 6 to 15 μm.

By classifying the polymer microspheres, polymer microspheres having a desired average center diameter were obtained.

Next, dry polymer microspheres Lo with average central diameter (Dn) = 10.08 Bm and standard deviation (σ) = 0.28 μm
On the other hand, 100 g of 95% concentrated sulfuric acid was placed in a 200 ml beaker, and the polymer microspheres were gradually added to the beaker while stirring with a magnetic stirrer. Acid treatment was performed by reacting at 55°C for 6 hours.

Thereafter, the acid-treated microspheres obtained were filtered and thoroughly washed with water. On the other hand, 6 g of the basic dye Cachilon Black 5B11 (manufactured by Udougaya Kagaku ■) was dissolved in 300-g water, and acetic acid was added to prepare a dye bath whose pH was adjusted to 4.

Next, the acid-treated microspheres were added to this dye bath and dyed at 95°C for 6 hours. Next, the excess dye bath was filtered off and washed with water to obtain microspheres dyed black.

When the obtained colored microspheres were observed under a microscope with a magnification of 400 times, all of the microspheres were stained black, and no uncolored microspheres were observed. Further, when the colored microspheres were immersed in water and various solvents and the dissolution of the dye was visually observed, no dissolution of the dye was observed.

1 base l Instead of divinylbenzene and dipentaerythritol hexaacrylate used in Example 1, 187.5 g of tetramethylolmethane triacrylate, 562.5 g of tetraethylene glycol dimethacrylate, and 500 g of methacrylic acid were used. Other than that, Example 1
The operation was carried out under the same conditions as above, and the average center diameter (Dn) was 5 to 5.
Crosslinked polymer microspheres of 15 μm were obtained.

Next, take 3 g of dried microspheres classified into average center diameter (Dn) -8.36 μm and standard deviation (σ) = 0.33, add this to 30 g of concentrated sulfuric acid, and leave at room temperature (25°C).
Acid treatment was carried out for 3 hours. Next, the mixture was filtered and washed with water to obtain acid-treated polymer microspheres. On the other hand, the basic dye Catilon Brilliant Scarlet CD-GLll (manufactured by Odogaya Chemical) Ig was dissolved in 100-water, and acetic acid was added to adjust the pH.
Create a dye bath adjusted to =4. The above acid-treated polymer microspheres were added to this dye bath and dyed at 95°C for 1 hour. The filtrate became completely clear and the dye stained 100% of the microspheres.

After filtering, the dyed polymer microspheres were washed with water 4 to 5 times, and then dried to obtain colored microspheres dyed red.

When the obtained colored microspheres were observed under a microscope with a magnification of 400 times, all of the microspheres were stained red, and the presence of uncolored microspheres was not observed.

Further, when the colored microspheres were immersed in water and various solvents and the dissolution of the dye was visually observed, no dissolution or dissolution of the dye was observed.

Manufacture of colored microspheres using charcoal: Using 30 parts by weight of dipentaerythritol hexaacrylate and 60 parts by weight of divinylbenzene, the same operation as in Example 1 above was carried out to obtain an average center diameter (D) of 6.48 μm. ,
10 g of crosslinked polymer microspheres with standard deviation (σ) = 0.36
I got it. Next, the crosslinked polymer microspheres Log were gradually added to a 200 d beaker containing 30 g of 95% sulfuric acid under stirring, followed by heat treatment at 60'C for 3 hours. Next, the sulfuric acid was filtered off, and the microspheres were washed with water to obtain acid-treated crosslinked polymer microspheres. On the other hand, a commercially available black basic dye (Catilon Black 5B11).

A dye bath was prepared by dissolving 6 g (manufactured by Udogaya Kagaku ■) in 300 d of water and adjusting the pH to 4 with acetic acid.The above acid-treated microspheres were added to this dye bath and dyed at 95"C for 5 hours. After the dye bath was filtered off, the colored microspheres were washed with water and then with acetone to remove undyed dye molecules to obtain colored crosslinked polymer microspheres.

When these colored microspheres were observed under a microscope with a magnification of 400 times,
All particles were optically uniformly dyed black, and there were no uncolored particles.

<Measurement of light transmittance of colored microspheres> 1 g of colored microspheres obtained by the above method was dispersed in 100 d of fluorocarbon, and this was dispersed into a 1 m thick x 10 m wide space.
The colored microspheres were cast onto a glass plate of X @ 130 mm, covered with glass plates of the same size so as to sandwich the colored microspheres, and then lightly pressed and fixed in two places with adhesive tape so as to span the upper and lower glass plates. Next, this material was placed in an oven at 50°C to evaporate the freon, creating two samples in which colored microspheres were present in a single layer close-packed between two glass plates. . When this sample was observed under an optical microscope with a magnification of 100 times, colored microspheres were gathered in a honeycomb shape and arranged in a single layer, and it was confirmed that the sample was the desired sample.

Next, the two samples were stacked one on top of the other, and the two samples were fixed with adhesive tape so as to extend above and below the sample, thereby obtaining a sample for visible light transmittance measurement.

Four glass plates containing no colored microspheres were used as controls, and the visible light transmittance of the above samples in the range of 400 nm to 800 nm was measured using a spectrophotometer. As a result, 400 nm to 800 nm
The transmittance was 3 to 5% or less over the entire range of m.

Further, when the spectral reflectance of the above sample was measured over the entire range from 400 nm to 800 nm using magnesium oxide as a standard white plate, the reflectance was 0%.

From the above results and the results of observing the colored microspheres under a 400x optical microscope, it was confirmed that the colored microspheres obtained by the method of the present invention were dyed in an extremely deep color.

(Effects of the Invention) As described above, the present invention involves treating polymer microspheres obtained by polymerizing a monomer having an ethylenically unsaturated group with an acid, and then treating the polymer microspheres treated with this acid with an acid. Because it is dyed,
A dye can be chemically bonded to the polymeric microspheres. Therefore, it is possible to uniformly and deeply color the colored microspheres with a small amount of dye, without reducing the physical strength of the colored microspheres.

Furthermore, the dye bound to the colored microspheres does not separate from the colored microspheres, resulting in excellent solvent resistance.In addition, unlike conventional methods, starting materials are limited to reactive dyes, and the polymerization rate and degree of polymerization are improved. does not decrease.

that's all

Claims (1)

[Claims] 1. Treating polymer microspheres obtained by polymerizing a monomer having an ethylenically unsaturated group with an acid, and then dyeing the polymer microspheres treated with the acid. A method for producing colored microspheres characterized by: 2. The colored microspheres according to claim 1, wherein the monomer having an ethylenically unsaturated group contains 5% by weight or more of a monomer having two or more ethylenically unsaturated groups. Production method. 3. The monomer having two or more ethylenically unsaturated groups is x methylol alkyl y (meth)acrylate (where x and y are integers satisfying the condition x≧y≧2),
Claim 2 is at least one selected from the group consisting of polyoxyalkylene glycol di(meth)acrylate, triaryl(iso)cyanurate, triaryltrimelite, divinylbenzene, diarylphthalate, and diarylacrylamide. A method for producing colored microspheres as described. 4. The acid treatment agent is concentrated sulfuric acid, fuming sulfuric acid, sulfur trioxide, sulfurous acid, sulfite, bisulfite, sulfonyl chloride,
The method for producing colored microspheres according to any one of claims 1 to 3, wherein the colored microspheres are at least one selected from the group consisting of chlorosulfuric acid, fluorosulfuric acid, and aminosulfonic acid. 5. The method for producing colored microspheres according to any one of claims 1 to 4, wherein the dye to be dyed is a basic dye.