JPH0564735A - Dispersant and inorganic fine particle dispersion using the same - Google Patents

Abstract

PURPOSE:To obtain a dispersant having good dispersing function and improved in the compatibility with an org. component by using a polymer containing alpha,beta-monoethylenic unsaturated carboxylic acid or a salt thereof as a principal constituent monomer as the dispersant dispersing fine particles in alkylene glycol. CONSTITUTION:A polymer containing alpha,beta-monoethylenic unsaturated carboxilic acid or a salt thereof as a principal constituent monomer is used as a dispersant dispersing fine particles of titanium dioxide or calcium carbonate in alkylene glycol such as ethylene glycol. The ratio of alpha,beta-monoethylenic unsaturated carboxylic acid or a salt thereof is set to 20% or more, pref., 40% or more by wt. of all of monomers. This dispersant well disperses fine particles of pigment or the like.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dispersant, and more specifically, it is suitable for dispersing inorganic fine particles such as pigments (hereinafter, simply referred to as fine particles) in alkylene glycol such as ethylene glycol. And a fine particle dispersion in which the agent is dispersed.

[0002]

2. Description of the Related Art At present, fine particles, particularly fine particles of titanium dioxide, barium sulfate, calcium carbonate, talc, kaolin and the like are widely used in large amounts as fillers or pigments for rubber, plastic, paper, paints and the like. For example, in the paper manufacturing industry, a large amount of calcium carbonate is used together with talc and kaolin, but calcium carbonate with good dispersibility is required in order to emphasize the surface gloss of coated paper, and there are many aggregate particles in water. In place of calcium carbonate powder, which is difficult to disperse in water, a high-concentration aqueous dispersion prepared by a calcium carbonate manufacturer is supplied to a paper manufacturer in the form of a dispersion and used. This high-concentration aqueous dispersion of calcium carbonate is easy to prepare because a good dispersant such as an aqueous solution of sodium polyacrylate is commercially available.

Among the above-mentioned fine particles, particularly fine particles prepared by paying attention to the uniformity and dispersibility of the particle diameter, for example, synthetic silica prepared by hydrolyzing alkoxysilane and the like, and synthetic particles having a specific dispersity. Fine particles such as calcium carbonate prepared by crushing calcium carbonate under specific conditions and kaolin prepared by repeating advanced centrifugal classification are polyester films used as materials for magnetic tapes such as audio tapes and video tapes. Used as an anti-blocking agent. In order to improve the dispersibility of these inorganic compounds in polyester, a glycol dispersion of fine particles is prepared and added to the polyester manufacturing process. When the glycol in which the fine particles are suspended is stored for a long period of time, the fine particles settle and precipitate, forming a hard hard cake and making it difficult to re-disperse it. There is also a drawback that the inorganic compound is aggregated during the production of. If agglomerated coarse particles are present in the polymer, it may cause yarn breakage during spinning of the polyester fiber, or cause coarse protrusions in the film, fish eyes, etc., particularly when used for a magnetic tape film,
Development of a fine particle dispersion technique that does not generate agglomerated coarse particles is awaited because it causes dropout and a decrease in S / N ratio.

In the polyester film,
The slipperiness and abrasion resistance are major factors that influence the workability of the film manufacturing process and the processing process in each application, and further the quality of the product. When these slipperiness and abrasion resistance are insufficient, for example, when a polyester film surface is coated with a magnetic layer and used as a magnetic tape, friction between the coating roll and the film surface during application of the magnetic layer is severe, and The surface of the film is abraded by the abrasion, and in extreme cases, wrinkles, scratches, etc. are generated on the surface of the film. Even after slitting the film after applying the magnetic layer and processing it into audio, video, or computer tape, etc., many guides, playback heads, etc., when pulling out from the reel or cassette, winding, etc. Abrasion occurs remarkably, and scratches, distortions are generated, and as a result of depositing a white powder substance due to abrasion of the polyester film surface, etc., it often becomes a major cause of loss of magnetic recording signal, that is, dropout. ..

This is because the affinity between the fine particles and the polyester, which is the organic component, is not sufficient, so that peeling occurs at the boundary between the particles and the polyester during stretching, and voids are generated.
When the voids are present in the polyester, the particles are easily detached from the polyester film due to damage of the polyester film or the like due to contact between the polyester film or the polyester film and other base material. For example, in the magnetic tape film as described above. This may cause white powder and dropout. Also, since there are large voids around the particles, the transparency of the polyester film is impaired. Therefore, the lack of affinity between the fine particles and polyester is considered to be a problem to be solved in terms of abrasion resistance and transparency.

Therefore, as described above, a dispersant having a suitable dispersing function to be used when dispersing fine particles in an alkylene glycol such as ethylene glycol, and preferably having a good compatibility with an organic component. Was eagerly awaited for development. For such a purpose, when a known dispersant such as used in calcium carbonate for papermaking as described above is used, for example, an aqueous solution of sodium polyacrylate or the like, there is a risk of aggregation of pigment particles called “pigment shock”. The particles that have been extremely dispersed and prepared by using advanced synthesis technology and pulverization and classification technology can be agglomerated into coarse particles in an instant and cannot be used as an anti-blocking material such as polyester film. Could be.

[0007]

In view of the above situation, the present inventors have a suitable dispersing function when dispersing fine particles in an alkylene glycol such as ethylene glycol, and are preferably compatible with an organic component. As a result of earnest studies on a dispersant having a good function, the present invention was completed by discovering that a dispersant containing an alkylene glycol such as ethylene glycol as a solvent has extremely good characteristics.

Therefore, an object of the present invention is to use a dispersion function suitable for dispersing silica, kaolin, talc, titanium dioxide, calcium carbonate, barium sulfate, and other fine particles in alkylene glycol such as ethylene glycol. And preferably to provide a dispersant having a good compatibility with an organic component.

[0009]

The present invention is an alkylene glycol-containing dispersant obtained by dissolving a polymer and / or copolymer having a specific composition in a solvent containing alkylene glycol.

That is, the first aspect of the present invention is to disperse a polymer having α, β monoethylenically unsaturated carboxylic acid or a salt thereof as a main constituent monomer in a solvent containing alkylene glycol. And the second aspect of the present invention includes an inorganic fine particle dispersion liquid in which inorganic fine particles are dispersed with the above dispersant.

In the present invention, the α, β monoethylenically unsaturated carboxylic acid includes acrylic acid, methacrylic acid,
Examples thereof include α, β unsaturated monocarboxylic acids selected from crotonic acid and the like, α and β unsaturated dicarboxylic acids selected from maleic acid, itaconic acid, fumaric acid and the like.

Further, the polymer in the present invention is a polymer having α, β monoethylenically unsaturated carboxylic acid or a salt thereof as a main constituent monomer, and α, β monoethylenically unsaturated carboxylic acid or its salt Examples thereof include one or more homopolymers or copolymers of salts, and copolymers of α, β monoethylenically unsaturated carboxylic acids or salts thereof and monomers having copolymerizability therewith. As the monomer having copolymerizability with α, β monoethylenically unsaturated carboxylic acid or a salt thereof,
The following may be mentioned: (a) methyl acrylate, ethyl acrylate, propyl acrylate, isobutyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, isobutyl methacrylate,
Acrylic alkyl esters and methacrylic acid alkyl esters such as 2-ethylhexyl methacrylic acid (b) Acrylates and methacrylates having alkoxy groups such as methoxyethyl acrylate, methoxyethyl methacrylate, ethoxyethyl acrylate, ethoxyethyl methacrylate (c) Cyclohexyl acrylate, cyclohexyl Acrylate and methacrylate having cyclohexyl group such as methacrylate (d) α, β monoethylenically unsaturated hydroxy ester such as 2-hydroxyethyl acrylate and 2-hydroxyethyl methacrylate (e) Polyethylene glycol monoacrylate, polyethylene glycol monomethacrylate, poly Pyropyrene glycol monoacrylate, polypyropyrene glycol Methacrylates, polyalkylene glycol monoacrylates and monomethacrylates such as methacrylate, polyethylene glycol polypropylene glycol monomethacrylate, polyethylene glycol polytetramethylene glycol monomethacrylate, methoxypolyethylene glycol monomethacrylate (f) vinyl esters such as vinyl acetate and vinyl stearate (g ) Vinyl aromatics such as styrene and vinyltoluene (h) Unsaturated nitriles such as acrylonitrile and methacrylonitrile (i) Unsaturated dicarboxylic acid esters such as monomethyl maleate and dibutyl itaconate (j) Methyl vinyl ether, butyl vinyl ether, etc. Vinyl ether (k) of butadiene, ethylene, propylene, n-butene, isobutene, conjugated diene such as n-pentene, Olefin.

At least one selected from α, β monoethylenically unsaturated carboxylic acids or salts thereof, and another monomer copolymerizable with the α, β monoethylenically unsaturated carboxylic acids or salts thereof. In the copolymer (1), the proportion of the α, β monoethylenically unsaturated carboxylic acid or its salt in all monomers is preferably 20% by weight or more, and particularly preferably 40% by weight or more. If the amount of the α, β monoethylenically unsaturated carboxylic acid or its salt is less than 20% by weight, that is, if the amount of the other monomer copolymerizable with them is more than 80% by weight, the dispersibility of the fine particles becomes insufficient. There is a possibility that it will be sufficient.

As the monomer copolymerizable with the α, β monoethylenically unsaturated carboxylic acid or its salt, polyalkylene glycol monoacrylate or monomethacrylate is preferable, and similarly, it is used in an amount of 80% by weight or less. , 5 in order to fully exert the effect of the monomer.
It is preferable to use from 50% by weight to 50% by weight.

The carboxyl group present in the polymer or copolymer is preferably a completely neutralized salt or a partially neutralized salt with an alkali metal, ammonium, amine or the like from the viewpoint of improving the dispersibility of fine particles. .

Further, the molecular weight of the polymer or copolymer constituting the present invention is 5 from the viewpoint of the dispersion effect of fine particles.
It is preferably 0000 or less, and in terms of viscosity, 40
The viscosity of the wt% aqueous solution is preferably 5000 cps or less, and particularly preferably 3000 cps or less (B-type viscometer, 25 ° C.,
Rotor speed 60 rpm).

The alkylene glycol in the present invention has, for example, 2 to 10 carbon atoms such as ethylene glycol, propylene glycol, butylene glycol, trimethylene glycol, tetramethylene glycol, pentamethylene glycol, hexamethylene glycol and decamethylene glycol. Examples of the polymethylene glycol, alicyclic diols such as cyclohexanedimethanol, and the like can be used alone or in combination of two or more kinds. From the viewpoint that the alkylene glycol-containing dispersant of the present invention does not impair the water solubility, alkylene glycols having 4 or less carbon atoms such as ethylene glycol, propylene glycol and butylene glycol are preferred, and ethylene glycol is most preferred.

The ratio of alkylene glycol to 100 parts by weight of the polymer in the dispersant of the present invention is preferably 1 part by weight or more, more preferably 10 parts by weight or more. If it is less than 1 part by weight, the effect of dispersing fine particles suspended in alkylene glycol may be insufficient,
When the amount exceeds 150 parts by weight, it is necessary to use a large amount of the dispersant of the present invention in order to sufficiently disperse the fine particles, and as a result, the concentration of the fine particles in the alkylene glycol dispersion liquid is significantly reduced, which is preferable. Absent.

The dispersant of the present invention can be easily prepared by using a usual vinyl monomer polymerization method. As an example of the preparation method, a component which is a polymerizable monomer such as α, β monoethylenically unsaturated carboxylic acid which is a constituent component of the polymer used in the present invention, and a usual polymerization initiator, for example, A water-soluble persulfate such as potassium persulfate is used in an amount of, for example, 0.1 to 10% by weight based on all monomers, and a solvent containing an alkylene glycol such as ethylene glycol, for example, a mixed solvent of water and ethylene glycol, or Polymerization is performed at about 50 to 150 ° C. for about 1 to 10 hours in a mixed solvent of alcohol such as ethanol and ethylene glycol or a mixed solvent of water, ethanol and ethylene glycol, and water and ethanol are added after the completion of the polymerization as necessary. It is easily prepared by distilling a part of the solution under reduced pressure, and then adjusting the pH appropriately with an alkali metal salt or aqueous ammonia, if necessary. It is possible.

Regarding the timing of adding the alkylene glycol, as shown in the above-mentioned preparation method, it may be added to the solvent before the initiation of the polymerization, but the polymerization reaction is carried out without adding the alkylene glycol to the solvent before the initiation of the polymerization. After the completion of the polymerization reaction, alkylene glycol such as ethylene glycol may be added later. Furthermore, it may be prepared by dissolving a powder obtained by polymerizing the above-mentioned polymerizable monomer in alkylene glycol.

[0021]

The present invention will be described in more detail below with reference to examples, but the present invention is not limited thereto. The measurement of the particle size by the light transmission type particle size distribution measuring instrument in this example is a measurement and calculation in the following manner. Measuring model: Shimadzu SA-CP3 Measuring method: Solvent: ion-exchanged water with polyacrylic acid sodium 0.004
Aqueous solution dissolved by weight% Pre-dispersion: Ultrasonic dispersion 100 seconds Measurement temperature: 25.0 ° C. ± 2.5 ° C. Measurement method: As in the following calculation example. DP1: Light transmission type particle size distribution measuring device (Shimadzu SA-
In the particle size distribution measured using CP3), the particle size at the time of cumulative weight of 25% calculated from the large particle size side (μ
m) DP2: Light transmission type particle size distribution measuring instrument (SA-made by Shimadzu Corporation)
In the particle size distribution measured using CP3), the particle size at the time of cumulative 50% calculated from the large particle size side (μ
m) DP3: Light transmission type particle size distribution measuring instrument (Shimadzu SA-
In the particle size distribution measured using CP3), the particle size when the cumulative weight of 75% calculated from the large particle size side (μ
m) DP1,2,3 calculated from the above particle size distribution measurement results are as follows. DP1 = 0.80 + (28.0-25.0) × (1.00-0.80) ÷ (28.0-18.0) = 0.86 DP2 = 0.50 + (58.0-50. 0) × (0.60−0.50) ÷ (58.0−42.0) = 0.55 DP3 = 0.30 + (82.0−75.0) × (0.40−0.30) ÷ (82.0-72.0) = 0.37

Reference Example The inorganic fine particles (synthetic spherical silica) used in this example were prepared in the following manner. NaO in 81.0 g of water
H 0.006 g was dissolved, and 2.3 g of silica sol was added,
Further, 100 g of ethanol was added and stirred, and the obtained mixed system was maintained at 35 ° C. Ammonia gas was introduced into this mixed system to control the pH to 11.5, and a mixed liquid of 600 g of ethanol and 540 g of water and 320 g of 28% ethyl silicate were gradually added simultaneously over 16 hours. From the scanning electron micrograph measurement results, the obtained particles were spherical silica having a particle diameter of 0.2 μm.

Example 1 100 parts by weight of acrylic acid as a monomer, 3 parts by weight of ammonium persulfate as a polymerization initiator, 70 parts by weight of ethanol as a solvent, 79 parts by weight of propylene glycol, and 32.2 parts by weight of water. Acrylic acid was polymerized by a conventional method in a mixed solvent. The polymerization temperature was 80 ° C., and acrylic acid and ammonium persulfate were added dropwise to the solvent in about 5 hours. After completion of the polymerization, most of the ethanol was removed, and 115.8 parts by weight of 48% by weight NaOH aqueous solution was added as a neutralizing agent to adjust the pH to 7.5.
To prepare a dispersant composed of a polymer solution of sodium polyacrylate. Table 2 shows the physical properties of the alkylene glycol-containing dispersant obtained in this example.

Examples 2 to 5 The polymerization reaction was carried out in the same manner as in Example 1 except that the monomers, the polymerization initiator, the solvent, the neutralizing agent and the polymerization temperature were changed to those shown in Table 1. Table 2 shows the physical properties of the alkylene glycol-containing dispersant obtained in this example.

Example 6 The procedure of Example 1 was repeated except that the polymerization reaction was carried out without adding propylene glycol to the solvent before the initiation of the polymerization, and propylene glycol was post-added and mixed to the polymer solution after the addition of NaOH. Under the same conditions as in Example 1, a dispersant comprising a polymer solution of sodium polyacrylate was obtained. Table 2 shows the physical properties of the alkylene glycol-containing dispersant obtained in this example.

Comparative Examples 1 to 4 The polymerization reaction was carried out in the same manner as in Example 1 except that the monomers, the polymerization initiator, the solvent, the neutralizing agent, and the polymerization temperature were set as shown in Table 3. Table 3 shows the physical properties of the alkylene glycol-free dispersant obtained in this comparative example.

[0027]

[Table 1]

[0028]

[Table 2]

[0029]

[Table 3] The numbers in Table 1 and Table 3 in which the units in the monomer composition, the polymerization initiator, the solvent, and the neutralizing agent are not described all represent parts by weight. The details of the abbreviations in Tables 1 and 3 are shown below. AA ... acrylic acid, MMA ... methacrylic acid, ITA ... itaconic acid, MA ... methyl acrylate AN ... acrylonitrile, PGMMA ... polyethylene glycol monomethacrylate (molecular weight: about 40
0) St ... Styrene, VAC ... Vinyl acetate APS ... Ammo persulfate, AIBN ... Azobisisobutyronitrile EtOH ... Ethyl alcohol, H ₂ O ... Water IPA ... Isopropyl alcohol, MeOH ...
Methyl alcohol PG ... propylene glycol, EG ... ethylene glycol the DEG ... diethylene, NaOH · sodium hydroxide NH ₄ OH · · ammonium hydroxide thio ... molecular weight modifier viscosity ... 40% concentration , 25 ℃, measured by B-type viscometer

Example 7 The alkylene glycol-containing dispersant obtained in Example 1 was added to the mixed system of spherical silica, ethanol, and water obtained in the above-mentioned Reference Example as a polymer to give 3.0% of the spherical silica solid content. After adding wt% and stirring, ethylene glycol was added and flushing was performed using a rotary evaporator to remove water and ethanol from the mixed system, the residual rate of water was 0.4%, and the solid content concentration of spherical silica was 20%. .0
A wt% ethylene glycol dispersion was obtained. Example 7
Table 4 shows the results of measuring the particle size distribution of the ethylene glycol dispersion liquid of the spherical silica obtained in the above. From the results of particle size distribution measurement in Table 4, it can be seen that the spherical silica ethylene glycol dispersion obtained in Example 7 has very good dispersibility.

Examples 8 to 12 The alkylene glycol-containing dispersant used in Example 7 was changed to the alkylene glycol-containing dispersant shown in Table 4, and the solid content concentration of the spherical silica was 20% by weight. An ethylene glycol dispersion was obtained. Example 8-
Table 4 shows the particle size distribution measurement results of the ethylene glycol dispersion of spherical silica obtained in No. 12. From the results of particle size distribution measurement in Table 4, it can be seen that the ethylene glycol dispersions of spherical silica obtained in Examples 8 to 12 have very good dispersibility.

Comparative Examples 5 to 8 In the same manner as in Example 7, except that the alkylene glycol-containing dispersant used in Example 7 was changed to the alkylene glycol-containing dispersant, the solid concentration of spherical silica was 20% by weight. An ethylene glycol dispersion was obtained. This Comparative Example 5
Table 4 shows the results of measuring the particle size distribution of the ethylene glycol dispersion of spherical silica obtained in No. 8. From the results of particle size distribution measurement in Table 4, the ethylene glycol dispersions of spherical silica obtained in Comparative Examples 5 to 8 contained aggregate particles and had poor dispersibility.

[0033]

[Table 4]

Dispersibility test Examples 7, 8, 9, 10, 11, 12 and Comparative Example 5,
The ethylene glycol dispersion of spherical silica prepared in 6, 7, and 8 was further diluted with ethylene glycol to prepare 1
A 0 wt% dilution was prepared. Immediately after the preparation of these 10% by weight diluted solutions and after standing still for 24 hours, a 0.8 μm membrane filter (manufactured by Millipore) was pressure filtered under the condition of ² kg / cm ² and the passing amount was measured. The measurement results are shown in Table 5. From the results of Table 5, the ethylene glycol dispersion liquid of spherical silica prepared in each example has better filterability than that of the ethylene glycol dispersion liquid of spherical silica prepared in the comparative example, and It is confirmed that the filter is not clogged due to the generation of secondary agglomerated coarse particles and the dispersibility with time is good.

[0035]

[Table 5]

Application Example After transesterifying 100 parts by weight of dimethyl terephthalate and 70 parts by weight of ethylene glycol with 0.035 parts of manganese acetate tetrahydrate as a catalyst in a conventional manner, ethylene of spherical silica prepared in Example 7 was used. The glycol dispersion was added with stirring so that the spherical silica concentration was 4000 ppm with respect to the polymer. Then, polycondensation reaction was carried out in a usual manner under high temperature vacuum to obtain polyethylene terephthalate having an intrinsic viscosity of 0.630. This polymer was melt extruded at 290 ° C., stretched 3.5 times in the longitudinal direction at 90 ° C. and 3.5 times in the transverse direction at 130 ° C., and then heat treated at 220 ° C.
A film having a thickness of 5 μm was prepared. This film is A
It was measured according to STM-DO1894-63T. The maximum surface roughness of the obtained film was 0.106 μm.

Comparative Application Example The same operation as in Application Example was carried out except that the ethylene glycol dispersion liquid of spherical silica prepared in Comparative Example 5 was used. The maximum surface roughness of the obtained film was 0.250 μm, and coarse protrusions were conspicuous.

Front page continuation (72) Inventor Yuji Kawamura 1-1 Funami-cho, Minato-ku, Nagoya-shi, Aichi Toagosei Chemical Industry Co., Ltd. Nagoya Research Institute (72) Inventor Minoru Okada Funami-cho, Minato-ku, Aichi Prefecture No. 1 No. 1 Toagosei Chemical Industry Co., Ltd. Nagoya Research Institute

Claims (6)

[Claims] 1. A dispersant obtained by dissolving a polymer containing α, β monoethylenically unsaturated carboxylic acid or a salt thereof as a main constituent monomer in a solvent containing alkylene glycol. 2. The proportion of the α, β monoethylenically unsaturated carboxylic acid or its salt in all the constituent monomers is 20% by weight.
The dispersant according to claim 1, which is the above. 3. The dispersant according to claim 1, wherein the salt of α, β monoethylenically unsaturated carboxylic acid is at least one salt selected from alkali metal salts, ammonium salts and amine salts. 4. The dispersant according to claim 1, wherein the content of the alkylene glycol in the solvent is 1 part by weight or more and 150 parts by weight or less per 100 parts by weight of the polymer. 5. The dispersant according to claim 1, wherein the polymer according to claim 1 is a copolymer having polyalkylene glycol monoacrylate or monomethacrylate as a constituent monomer. 6. An inorganic fine particle dispersion liquid obtained by dispersing with the dispersant according to claim 1.