JPH0768392B2 - Method for producing colored microspheres - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing colored microspheres which are useful for various labeling materials, standard particles, diagnostic carriers, spacers for liquid crystal display devices, 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 a colored microsphere by dispersing a colorant such as a pigment in a monomer and then polymerizing the mixture.

(2) A method of dispersing or dissolving an oil-soluble dye in a monomer and then polymerizing this mixture.

(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 the above (1) has a drawback that it is difficult to uniformly disperse the colorant in the monomer, and transparent particles that are not colored are formed. Further, in the method of mixing this pigment into the resin, the hiding power is insufficient, so that it is necessary to add a large amount of the pigment. Therefore, the obtained colored microspheres have the drawbacks of low strength and slow polymerization rate.

In the method according to (2) above, the solvent resistance of the obtained colored microspheres is poor. Moreover, there are drawbacks such that the dye may be discolored by the polymerization catalyst, and the dye may not polymerize because it has a polymerization inhibiting effect.

In the method according to the above (3), since the reactive dye is used as the starting material, the type of the material is restricted and
There is a drawback that the degree of polymerization does not rise.

The method according to the above (4) has the drawbacks that colored microspheres dyed in a dark color cannot be obtained and that if the colored microspheres are treated with a solvent, the dye easily separates from the surface of the microspheres. Inferior in solvent).

The present invention solves the above drawbacks, and its purpose is to:
Color that can be uniformly and darkly colored, does not reduce the physical strength of the microspheres, has excellent solvent resistance, and that the starting materials are not limited to reactive dyes and that the degree of polymerization can be increased It is to provide a method for producing microspheres.

(Means for Solving the Problems) The method for producing a colored microsphere of the present invention is to combine an acid with an acid-treating agent to a polymer microsphere obtained by polymerizing a monomer having an ethylenically unsaturated group. It is characterized by binding and then staining the polymer microspheres chemically bound with this acid,
Thereby, the above object is achieved.

Hereinafter, the present invention will be described in detail.

The monomer having an ethylenically unsaturated group is composed of only a monomer having two or more ethylenically unsaturated groups, or composed of only 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. Particularly, it is preferable to use a monomer having two or more ethylenically unsaturated groups in an amount of 5% by weight or more, particularly 10% by weight or more, based on the total amount of the monomers having an ethylenically unsaturated group. When the added amount of the monomer having two or more ethylenically unsaturated groups is less than 5% by weight based on the total amount of the monomers having an ethylenically unsaturated group, the obtained polymer microspheres are The hardness is low, and the polymer microspheres may not be dyed in a dark color.

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

x methylolalkyl y (meth) acrylate (where x and y are integers satisfying the condition of x ≧ y ≧ 2).
Specifically, tetramethylolmethane tetra (meth) acrylate, tetramethylolmethane tri (meth) acrylate, tetramethylolmethane di (meth) acrylate, trimethylolpropane tri (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)
There are acrylate, polypropylene glycol di (meth) acrylate and the like.

Triaryl (iso) cyanurate, triaryl trimerite, etc.

Divinylbenzene, diaryl phthalate, diaryl acrylamide, etc.

Examples of the monomer having one ethylenically unsaturated group copolymerizable with the monomer having two or more ethylenically unsaturated groups include, for example, styrene, vinyltoluene, acrylonitrile, and (meth) acryl. Examples thereof include acid alkyl esters, vinyl esters, (meth) acrylic acid, hydroxyalkyl (meth) acrylate, (meth) acrylamide, N-methylol (meth) acrylamide and NN-dimethylaminopropyl acrylamide.

Polymeric 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 not higher than the boiling point of the dispersion medium and each monomer. As a radical catalyst that can be used, a general radical generating catalyst such as an organic peroxide or an azo compound is preferably used. Examples of the organic peroxide include bezoyl peroxide, lauroyl peroxide, di-t-butyl peroxide and the like. Examples of the azo compound include 2,2′azobisisobutyronitrile and 2,2′azobis (2,4dimethylvaleronitrile).

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

By treating the polymer microspheres with an acid as described above, an acid is added to the unreacted ethylenically unsaturated groups remaining in the polymer microspheres, and / or an acid is subjected to a substitution reaction on the polymer microspheres. The acid will then chemically bond to the polymeric microspheres. In particular, by producing a polymer microsphere by using a large amount of a monomer having two or more ethylenically unsaturated groups, the above-mentioned acid is added to the ethylenically unsaturated group remaining in the polymer microsphere as a sulfonic acid. As an ester, it can be reacted under relatively mild processing conditions. Further, when the polymer microspheres are produced using a monomer having an aromatic nucleus, a sulfonic acid group can be introduced into the aromatic nucleus of the polymer microspheres by a sulfonation reaction.

Next, the polymer microspheres treated with the acid as described above are dyed. As the dyeing conditions, the dye concentration is 0.5 to 5% by weight, the dyeing solution is adjusted to pH 2 to 6 with acetic acid and acid soda, the bath ratio is 1:30 to 1:10, the treatment temperature is 60 to 120 ° C, and the treatment time is 30.
It can be done in minutes to 15 hours. As the dye to be used, for example, a basic dye capable of chemically bonding with the acid bonded to the polymer microspheres is preferably used. The basic dye is mainly a hydrochloride of an aromatic base containing a chromophore. The basic group, an amino group (-NH _2), alkylamino group [-N (CH _{3) 2],} and the like. It does not contain an acidic group, and the dye ion becomes a cation in an aqueous solution. Specific examples include triphenyl methane series, anthraquinone series, azo series, methine series and oxazine series.

By this dyeing treatment, the basic dye is ionically bonded to the sulfonic acid group in the polymer microsphere. Then, the colored microspheres are obtained by filtering and washing. By this operation, the residual dye and the inorganic salt by-produced by the above dyeing are removed. Therefore, not only the alkali metal but also the pure colored spheres containing no impurities can be obtained.

Colored microspheres obtained in this manner, for example, a labeling material,
It is suitably used for standard particles, artificial carriers for clinical diagnosis, spacers for liquid crystal display devices, and the like.

(Example) Below, this invention is demonstrated based on an Example.

Example 1 A 2.5-solution of 5% polyvinyl alcohol was prepared in a 5-separable flask equipped with a stirrer and a reflux condenser, and 625 g of divinylbenzene, 625 g of dipentaerythritol hexaacrylate, and 18.8 g of benzoyl peroxide were uniformly added thereto. The dissolved and mixed monomer solution was charged, the temperature was raised to 80 ° C. under stirring to carry out a polymerization reaction for 10 hours, and the temperature was further raised to 95 ° C. to carry out a polymerization reaction for 1 hour. Next, the mother liquor was separated and washed to obtain crosslinked polymer microspheres having a size of 6 to 15 μm. By classifying the polymer microspheres, polymer microspheres having a desired average center diameter were obtained.

Next, average center diameter (Dn) = 10.08 μm, standard deviation (σ)
10 g of 0.28 μm dry polymer microspheres was taken, while 100 g of 95% concentrated sulfuric acid was placed in a 200 ml beaker, and the polymer microspheres were gradually added to this beaker while stirring with a magnetic stirrer. Acid reaction was carried out by reacting at 55 ° C for 6 hours. Then, the obtained acid-treated microspheres were separated by filtration and washed thoroughly with water. On the other hand, 6 g of the basic dye carotene black SBH (manufactured by Hodogaya Chemical Co., Ltd.) is dissolved in 300 ml of water, and acetic acid is added to prepare a dye bath adjusted to pH = 4. Next, the above acid-treated microspheres were added to this dye bath and dyeing was carried out at 95 ° C. for 6 hours. Next, the surplus dyebath was filtered off and washed with water to obtain black microspheres.

When the obtained colored microspheres were observed under a microscope of 400 times, all the microspheres were dyed in black, and the presence of uncolored microspheres was not recognized. 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.

Example 2 Example 2 was repeated except that 187.5 g of tetramethylolmethane triacrylate, 562.5 g of tetraethyleneglycol dimethacrylate and 500 g of methacrylic acid were used instead of the divinylbenzene and dipentaerythritol hexaacrylate used in Example 1. The operation was performed under the same conditions as in Example 1 to obtain crosslinked polymer microspheres having an average central diameter (Dn) of 5 to 15 μm.

Next, average center diameter (Dn) = 8.36 μm, standard deviation (σ) =
3 g of dried microspheres classified to 0.33 were taken, added to 30 g of concentrated sulfuric acid, and acid-treated at room temperature (25 ° C.) for 3 hours.
Then, it was filtered and washed with water to obtain acid-treated polymer microspheres. On the other hand, basic dye carotene brilliant scarlet CD-
Dissolve 1 g of GLH (Hodogaya Chemical Co., Ltd.) in 100 ml of water,
Make a dyebath adjusted to pH = 4 by adding acetic acid. The above acid-treated polymer microspheres were added to this dye bath and dyeing was carried out at 95 ° C. for 1 hour. The filtrate became completely clear and the dye dyed 100% microspheres. After filtering, the dyed polymer microspheres are separated by 4 to 5
It was washed with water twice and then dried to obtain colored microspheres dyed in red.

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

Example 3 <Production of Colored Microspheres> 30 parts by weight of dipentaerythritol hexaacrylate and 60 parts by weight of divinylbenzene were subjected to the same operation as in Example 1 above, and the average central diameter (Dn) = 6.48 μm, standard deviation ( 10 g of crosslinked polymer microspheres with σ) = 0.36 were obtained. Next, 10 g of this cross-linked polymer microsphere was added to 200 ml containing 30 g of 95% sulfuric acid.
The mixture was gradually added to a beaker with stirring, and then heat-treated 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, 6 g of a commercially available black basic dye (Carotene Black SBH; Hodogaya Chemical Co., Ltd.) was dissolved in 300 ml of water to prepare a dye bath adjusted to pH 4 with acetic acid, and the acid-treated microspheres were added to the dye bath. Was added and stained at 95 ° C for 5 hours. After filtering out some valleys, the colored microspheres were washed with water and then with acetone to remove undyed dye molecules to obtain colored crosslinked polymer microspheres.

When this colored microsphere was observed under a microscope of 400 times, all the particles were optically uniformly dyed in black, and there were no uncolored particles.

<Measurement of Light Transmittance of Colored Microspheres> 1 g of colored microvoids obtained by the above method was dispersed in 100 ml of Freon, and this was cast on a glass plate having a thickness of 1 mm × a width of 10 mm × a length of 30 mm. Then, the colored microspheres were covered with glass plates of the same size so as to be sandwiched between them, and lightly pressed to fix the two places with the adhesive tape so as to cover the upper and lower glass plates. Then this one 50
The sample was placed in an oven at 0 ° C., the freon was evaporated, and two samples were prepared in which the colored microspheres were present in a single layer in the form of closest packing between the two glass plates. When this sample was observed with a 100 × optical microscope, it was confirmed that the colored microspheres were aggregated in a honeycomb shape and arranged in a single layer, which was a desired sample.

Next, these two samples were superposed, and the two samples were fixed with an adhesive tape so as to cover the upper and lower parts of the sample to obtain a sample for measuring visible light transmittance.

The visible light transmittance of 400 nm to 800 nm of the above sample was measured with a spectrophotometer using four glass plates containing no colored microspheres as a control. As a result, 3-5% over the entire range of 400nm-800nm
The transmittance was as follows. When the spectral reflectance of the above sample was measured over the entire range of 400 nm to 800 nm using magnesium oxide as a standard white plate, the reflectance was 0%.

From the above results and the observation result of the colored microspheres under an optical microscope of 400 times, it was confirmed that the colored microspheres obtained by the method of the present invention were dyed in an extremely dark color.

(Effects of the Invention) As described above, according to the present invention, an acid-treating agent chemically bonds an acid to polymer microspheres obtained by polymerizing a monomer having an ethylenically unsaturated group, and then Since the chemically bonded polymer microspheres are dyed, the dye that dyes the polymer microspheres can be chemically bonded. Therefore, it can be uniformly and darkly colored with a small amount of dye, and the physical strength of the colored microspheres is not lowered. Moreover, the dye bound to the colored microspheres does not separate from the colored microspheres,
The solvent resistance is excellent, and the starting materials are not limited to reactive dyes and the polymerization rate and the degree of polymerization are not lowered as in the conventional case.

Claims (5)

[Claims] 1. A polymer microsphere obtained by polymerizing a monomer having an ethylenically unsaturated group, to which an acid is chemically bonded by an acid treating agent, and then the acid is chemically bonded. A method for producing colored fine particles, which comprises dyeing. 2. The monomer having an ethylenically unsaturated group is a monomer having two or more ethylenically unsaturated groups.
The method for producing a colored microsphere according to claim 1, wherein the method comprises the content of at least wt%. 3. A monomer having two or more ethylenically unsaturated groups is x methylolalkyl y (meth) acrylate (where x and y are integers satisfying the condition of x ≧ y ≧ 2), The claim 2 which is at least one selected from the group consisting of polyoxyalkylene glycol di (meth) acrylate, triaryl (iso) cyanurate, triaryl trimerite, divinylbenzene, diarylphthalate and diarylacrylamide. A method for producing the colored microspheres described. 4. The acid treating agent is at least selected from the group consisting of concentrated sulfuric acid, fuming sulfuric acid, sulfur trioxide, sulfurous acid, sulfite, hydrogen sulfite, sulfonyl chloride, chlorosulfuric acid, fluorosulfuric acid and aminosulfonic acid. The method for producing a colored microsphere according to any one of claims 1 to 3, which is one or more kinds. 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.