JPH01250497A - Pigment dispersant for coated paper - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION A. OBJECTS OF THE INVENTION [Industrial Field of Application] The present invention relates to a pigment dispersant for coated paper. More specifically, the object is to provide a dispersant that has excellent dispersibility and stability, and is capable of obtaining an aqueous calcium carbonate dispersion with low viscosity even at high concentrations using a smaller amount.

[Prior Art] Conventionally, in order to obtain coated paper such as art paper or coated paper, various pigments such as calcium carbonate, clay, kaolin, etc. are dispersed in water together with a dispersant, and synthetic latex, synthetic latex, etc. are added to this dispersion.
The use of starch, casein, etc. as pigment binders is well known. These pigments used in the manufacture of coated paper meet the high level of printability required for coated paper.
In addition to improvements in quality such as glossiness, the use of pigments containing calcium carbonate is increasing from the conventional use of clay alone due to economic considerations. In addition, the trend toward neutral paper to prevent discoloration and deterioration of archival documents, which has recently become a problem, has led to an increasing trend toward the use of calcium carbonate.

Inorganic tripolyphosphates and organic polyacrylates are used as dispersants for such pigments. however,
There is a need for a dispersant that exhibits a good dispersion effect on calcium carbonate pigments used for purposes such as improving printability. Dispersants such as calcium carbonate for coated paper generally require the following requirements.

(1) In terms of economy and coated paper quality, it is possible to prepare a highly concentrated and low viscosity dispersion with good dispersibility with a small amount added.

(2) The pigment dispersion liquid has excellent oral stability of viscosity.

[Problems to be solved by the invention] Conventionally, as dispersants for pigments for coated paper such as calcium carbonate and clay, in addition to inorganic compounds such as sodium tripolyphosphate and sodium hexametaphosphate, organic polymer dispersants have been used. , polyacrylic acid sodium salt, acrylic acid-maleic anhydride copolymer soda salt.

A soda salt of an olefin-maleic anhydride copolymer or the like is used alone or in combination. However, such dispersants are still unsatisfactory in terms of dispersion effect and oral stability.

1. Structure of the Invention [Means for Solving the Problems] Therefore, the present inventors conducted extensive research to find a dispersant that has an excellent dispersion effect on coated paper pigments. It was discovered that co-low polymers of niterulomaleic acid derivatives exhibit excellent dispersion effects due to surface active action, and that these homologs can be used as excellent dispersants for coated paper pigments such as calcium carbonate and clay. 6 [In the formula, R is a saturated or unsaturated alkyl group having 4 to 8 carbon atoms, X and Y are an alkal metal,
Represents an ammonium ion, an organic ammonium ion, or an alkyl group (having 2 to 4 carbon atoms), and the number of repeating units n is 3 to 3.
60] According to the present invention, an excellent water-soluble oligomer-type teaching agent for dispersing fine powder pigments such as calcium carbonate and clay in water can be provided. Already, any dispersant can be used effectively for individual pigments from a large number of saponified alternating copolymers of maleic acid derivatives and alkyl vinyl ethers with different side chain alkyl group chain lengths and degrees of saponification. It has the advantage that it can be used selectively. In addition, it can be used as a mixed dispersant to provide versatility to mixed pigments.6 The alkyl vinyl nitellar maleic acid derivative co-low polymer with a narrow polymerization degree distribution width used in the present invention is a combination of a maleic acid derivative and an alkyl vinyl ether. It can be controlled by rapidly advancing the polymerization reaction according to the bulk polymerization method without using either a chain transfer agent or a solvent. Generally, maleic acid derivatives are copolymerized with various monomers to form alternating copolymers. However, the alternating copolymers of maleic acid derivatives and alkyl vinyl ethers obtained by the manual method have a high degree of polymerization, and the average number of repeating units ranges from several tens to thousands. Since the distribution width is wide, ranging from 2 to several thousand, its uses have been limited. Therefore, in order to obtain an oligomer with an extremely low degree of polymerization, it was necessary to perform a fractional precipitation treatment of the obtained copolymer.

In contrast, by rapidly advancing the polymerization reaction without using a chain transfer agent or solvent as described above, combined with the steric hindrance effect of bulky monomers such as maleic esters, polymerization with a repeating unit count of 2 is possible. including, but on average 3-6o
An oligomer with a low degree of polymerization and a narrow distribution width can be obtained. In addition, even when using a monomer that is not bulky, such as maleic anhydride, n due to its nature is much smaller than that obtained by conventional telomerization reaction, and low polymerization reaction is not effective for bulky monomers. However, oligomers with an average n of 11 or more and several tens or less, including oligomers with a degree of polymerization of 10 or less, can be obtained.

As the maleic acid derivative used in the production of this alkyl vinyl ether maleic acid derivative co-low polymer, maleic acid, similar unsaturated acids, their anhydrides, salts, esters, amides, etc. can also be used.

These are represented by the following general formula %, where each R' is selected from hydrogen, a methyl group and an ethyl group, and Z is hydrogen, an alkyl group having 2 to 4 carbon atoms,
For example, it is selected from a methyl group, an ethyl group, a propyl group, a butyl group, or an alkali metal group.

Examples include maleic acid, maleic anhydride, fumaric acid,
Methyl maleic acid, dimethyl maleic acid, dimethyl maleate, diethyl dimethyl maleate monomethyl monomethyl maleate, dibutyl diethyl fumarate,
These substances include di-n-propyl monoethyl fumarate, methyl ethyl maleate, monomethyl maleic anhydride, diethyl maleic anhydride, methyl ethyl maleic anhydride, sodium diethyl maleate, potassium diethyl fumarate, etc. Mixtures may also be used.

In addition, the alkyl group of the alkyl vinyl ether, which is the other component of the alternating copolymer, has 4 to 18 carbon atoms.
are used. Examples of this include ethyl vinyl ether, chloroethyl vinyl ether, n-propyl vinyl ether, n-butyl vinyl ether, l-butyl vinyl ether, inoctyl vinyl ether, n-dodecyl vinyl ether, etc., but preferably alkyl having 8 to 12 carbon atoms. Vinyl ethers exhibit particularly good dispersing effects.

The copolymer thus obtained is saponified or esterified with an alkali or alcohol, and then purified by a conventional method. Examples of the alkali used at this time include ammonia, caustic soda, caustic potash, lithium hydroxide, There are monoamines such as ethylamine and monoethanolamine. Further, examples of alcohol include ethanol, butanol, diethylene glycol, and the like. These can be reacted alone or in combination of two or more.

The present inventors previously filed a patent application for a pigment dispersant comprising a salt of a co-low polymer of alkyl vinyl nitellar maleic vinegar derivative of the present invention. (Japanese Patent Publication No. 60-9850) The present inventors further investigated the peripheral technology of the above-mentioned Japanese Patent Publication No. 60-9850, and found that Examples 1 to 4 described below
As shown in Figure 2, even when the alkyl vinyl ether has an alkyl group carbon number of 4 or more, and the copolymer of the present invention has a repeating unit number n of 10 or more, it has excellent dispersion as a dispersant for hydrophilic pigments such as calcium carbonate. We found that this method is effective.

The pigment dispersant for coated paper of Hon 5 and Akira is used for pigments such as calcium carbonate in the form of an aqueous solution, a water-containing solvent solution, and an organic solvent solution. Usually, the amount of f'E JIJ is 0.005 to 1.0% based on the pigment, preferably 0.
, 01 ” 0, 5%.

[Effect]

The characteristics of the pigment dispersant for coated paper obtained as described in 2 are as follows.

(]) - Excellent temporal dispersion effect. (2) Good sustainability of effects. (3) Effective at low addition amounts. (4) It has low toxicity and can be used over a wide range of areas.

The alkyl vinyl nitellar maleic acid derivative co-low polymer shown in the general formula according to the present invention has specificity in the structure of its alkyl group. In other words, the alkyl groups are oriented and adsorbed on the hydrophobic part of the pigment particle surface, imparting a negative charge to the pigment particles at a low addition amount, and are responsible for improving the fluidity of the pigment slurry at the same time as providing an excellent dispersion effect. Conceivable.

The alkylvinylnitellar maleic acid derivative low-level aggregation obtained by the present invention is used as an internal sizing agent for paper, such as calcium carbonate, which is used in tissue paper, urea, which is used in J-quality paper, and wallpaper. It can also be used as a dispersant for pearlescent face oils. Furthermore, since the copolymer of the present invention has an excellent dispersing effect as described above, it can also be used as a pigment dispersant for water-based paints.

[Examples] The present invention will be described in detail below with reference to Examples, but the present invention is not limited thereto.

[Example 1] 3.3 parts of α,α'-azobisisobutyronitrile (AI BN) was added to 93.6 parts of isooctyl vinyl ether and 103.3 parts of diethyl maleate, and the mixture was stirred under a nitrogen stream. The polymerization reaction was carried out at 145° C. for 1 hour. The number n of repeating units in this polymer was determined to be 4 on average by the boiling point elevation method. An aqueous solution prepared by dissolving an amount of caustic soda equivalent to 0.8 times the ester group content of this polymer in a minimum amount of water was added and heated to obtain Honkomei's co-low polymer (1) with a degree of saponification of 72%. .

C Example 2) Example 1: 60.1 parts of n-butyl vinyl ether, 103.3 parts of maleic acid diethyl, and 3.3 parts of AIBN.
After polymerization under the same reaction conditions, the ester group content of the polymer is saponified using a sorter, and the degree of sulfurization 47 (2) was obtained.

The average number of repeating units n was 5o.

[Example 3] 50.1 parts of n-butyl vinyl ether and 49.0 parts of maleic anhydride were heated to 95 to 135°C with stirring in a nitrogen stream.
The polymerization reaction was carried out for 2 hours. The average repeating unit number n of this product was 26 on average. This polymer was saponified with maleic acid residue and the same sodium hydroxide solution to obtain co-low polymer sodium salt (3).

[Example 4] 63.7 parts of n-dodecyl vinyl ether and 29.4 parts of maleic anhydride were polymerized under the same reaction conditions as in Example 3 to obtain co-low polymer sodium salt (4). The average number of repeating units of this product was 7.9 [Comparative Example] To 35.0 parts of methylvinyether and 1031 parts of diethyl maleate, 3 parts of \IB\: was added, and the reaction was carried out under pressure. Other than that, polymerization was carried out under the same conditions as in Example 1. 1°0 times the ester group content of this polymer (1° of the intended weight)
Comparative copolymer (1) with a degree of saponification of 90% was obtained by saponification with 5-carbonated soda. The number n of repeating units of this product was 4 on average.

[Comparative Example 2] Polymerization was carried out under the same conditions as in Example J, except that 3.3 parts of AIBN was added to 93.6 parts of isooctyl vinyl ether and 103.3 parts of diethyl maleate, and the polymerization reaction was carried out for 4 hours. This polymer was saponified with caustic soda in an amount equivalent to one time the ester group content, and a comparison copolymer (2
) was obtained. The average number n of repeating units in this product was 200.

[Comparative Example 3] Methyl vinyl ether 58.0 parts, maleic anhydride 98 parts
．． Polymerization was carried out under the same conditions as in Example 3, except that 0 part was reacted under pressure. This polymer was saponified with caustic soda in an amount equivalent to the maleic acid residue, and the comparative copolymer sodium salt (
3) was obtained. Repeating this, the number of units n is 200 on average
Met.

Next, Table 1 shows the measurement results for the dispersion effect of calcium charcoal for the polymers of Examples and Comparative Examples of the present invention. The dispersion test measurement method is as follows.

40 parts by weight of the combined water and 8 liquids shown in Table 1 below.

While stirring, add commercially available calcium carbonate (for example, particle size 0.
1-1.0μ) was added to obtain a calcium carbonate/water slurry having a solid content of 60 parts by weight. in this case,
The amount of polymer used was 0.1 and 0.5% by weight relative to calcium carbonate. Next, the viscosity of this slurry was measured at 20°C using a model 13 rotational viscometer.
Measurement was performed at 30 rpm.

Table 1 Dispersion effect of calcium carbonate (Note 1) From the beginning, high viscosity ′A was not measured over time (Note 2) Commercially available low molecular weight sodium polyacrylate (molecular weight 5000) Next, instead of calcium carbonate, clay ( tJL-TR
A WHITE, made by ENGELHARD, calibration diameter 2μ or less, 92%) was used, slurry) was 72% by weight as μ degree.
The experiment was conducted in the same manner except that the B-type rotational viscosity ε1 was set at 6 rpm.

Table 2 shows the measurement results of the dispersion.

Table 2 Dispersion effect of clay C, effect of Kaimei As shown in Tables 1 and 2, when the copolymer of the present invention is used as a dispersant for pigments for coated paper, it provides remarkable dispersion even at low concentrations. It is clear that it is effective.

Patent applicant: Toho Chemical Industry Co., Ltd.

Claims (1)

[Claims] General formula ▲ Numerical formula, chemical formula, table, etc. ▼ [In the formula, R is a saturated or unsaturated alkyl group having 4 to 8 carbon atoms, and Ion or alkyl group (2 or more carbon atoms)
4), and the number n of repeating units is 3 to 60.