JPS5883069A - Pigment dispersant - Google Patents

Abstract

PURPOSE:To provide a pigment dispersant which gives a dispersion exhibiting an excellent stability at a low viscosity even at a high concn., consisting of a copolymer (salt) obtd. from an alpha,beta-ethylenically unsaturated carboxylic acid, a specified addition reaction product and a (meth)acrylate ester. CONSTITUTION:A pigment dispersant consists of a copolymer (salt) obtd. by polymerizing 50-97.9wt% alpha,beta-ethylenically unsaturated carboxylic acid (A) such as acrylic acid, 0.1-20wt% addition reaction product (B) obtd. by reacting a glycidyl ether or a glycidyl ester with an alpha,beta-ethylenically unsaturated carboxylic acid, and 2-30wt% (meth)acrylate ester (C) in the presence of a polymn. initiator and in an aq. medium at 50-150 deg.C for 1-10hr. This dispersant is used in an amount of 0.05-5% based on the amount of a pigment.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a dispersant that can prepare a dispersion liquid that has low viscosity even at high concentrations and has excellent dispersion stability.

4IKI [Provides a dispersant used for dispersing paper stock.

Coated papers have traditionally been produced using various pigments such as kaolin, clay, calcium carbonate, titanium oxide, barium sulfate, satin white, and the like.

That is, coated paper is generally prepared by adding a dispersant to the pigment described above to form an aqueous dispersion, and then adding a pigment pie to the aqueous dispersion.

A machine that adds casein, starch, styrene/butadiene latex, etc. alone or as a mixture, coats the coating liquid thus obtained on base paper, then dries it, and then supercalends it. Manufactured using special treatment.

In the production of these coated papers, in order to obtain the best printability effect and to obtain this effect under relatively inexpensive production conditions, pigment dispersions are used in the production of coating liquids. When adjusting pigments, it is no longer just one type of pigment that is used, but a combination of various different pigments. Due to various requirements such as the increasing use of pigment dispersants and the desire to adjust the concentration of pigment dispersions due to their low water content, the dispersants used are also subject to the above-mentioned requirements. A highly sensitive pot with high flame resistance that can withstand immersion in water.Due to the quality of the coated paper, it is possible to prepare a highly concentrated pigment dispersion using a smaller amount.2 Pigment dispersion. Excellent viscosity stability &
There is a strong demand for effective dispersion effects for a wide variety of JII materials.

%, when reactive pigments such as calcium carbonate, sana/white, etc. are used, and furthermore, when relatively fine particles of these pigments are used, Secondary agglomeration is likely to occur, increasing the viscosity of this dispersion, reducing fluidity, and worsening the stability of the coating solution, which not only prevents good coating, but also prevents the resulting coated paper from being coated properly. The printing quality is poor and it is difficult to achieve the purpose. This poor dispersion state is due to the poor dispersion function of conventional dispersants, that is, the dispersion function of conventional dispersants is not sufficiently effective in preventing the above-mentioned secondary agglomeration, and conventional dispersants cannot be used. Pigment dispersions prepared using pigment dispersions may settle in a short period of time, undergo dispersion, or have a high viscosity immediately after dispersion, or even if the dispersion angle wave has a viscosity that is almost applicable to coating operations. Even if it is obtained, it has the disadvantage that the viscosity increases over time.

This adversely affects coatability and coated paper performance.

Conventionally, organic polymeric pigment dispersants such as sodium polyacrylate and acrylic acid/maleic anhydride copolymers have been widely used as pigment dispersants for coated paper; The diversification effect required under the circumstances is extremely unsatisfactory.

The present inventors conducted a more in-depth study on the above-mentioned dispersant for pigments for coated paper, and as a result, they discovered a dispersant having an excellent dispersion function and completed the present invention.

■ d, β-ethylenically unsaturated carboxylic acid ■ Glycidyl ethers or glycidyl esters and α, β-
Addition reaction product of ethylenically unsaturated carboxylic acid■ Acrylic acid ester and/or methacrylate dispersants have a significantly superior pigment dispersing effect compared to conventionally used sodium polyacrylates, etc., and can be used in small amounts. It is possible to perform this function.

Further, to describe the dispersant of the present invention in detail, the dispersant of the present invention has polymer constituents of α,β-ethylenically unsaturated carboxylic acid, glycidyl ethers, or glycidyl esters and α,β-ethylenically unsaturated carboxylic acid. The addition reaction product of acrylic acid and the eneneically unsaturated carboxylic acid include acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, and the like.

As addition reaction products of glycidyl ethers or glycidyl esters and α,β-ethylenically unsaturated carboxylic acids, glycidyl ethers or glycidyl esters and α,β-x-ethylenically unsaturated carboxylic acids are used. Addition reaction products or modified products obtained by reaction using known methods.

Its typical structural formula is glycidyl ether R1 In other words, Ru0O-0-CH, -0H-OH-0-A■ OH R.

■ Or Vi R, -Co-0-OH-OH-0-AOH
,0H (Aii furkyl group, aryl group, cycloalkyl group,
It represents an acyl group, and R1 is σ, except for the carboxyl group of β-ethylenically unsaturated carboxylic acid, and the 9th part also represents OH or H) f′. Here, as the α,β-ethylenically unsaturated carboxylic acid, those mentioned above are used, and as the glycidyl ethers or glycidyl esters, specifically, methyl glycidyl ether, ethyl glycidyl ether, butyl glycidyl ether, 2- Ethylhexyl glycidyl ether, lacryl glycidyl ether, butyl metaglycidyl ether, 7-enyl glycidyl ether, phenyl metaglycidyl ether, allyl glycidyl ether, metaglycidyl acetate, glycidyl propionate, glycidyl benzoate, glycidyl laurate A reaction example using phenylglycidyl ether as the ester and glycyl valmitate and acrylic acid as the β-ethylenically unsaturated carboxylic acid is as follows.

OH, OH (50 to 10% or less) These can be easily produced by known methods such as those described in JP-A-53-18637.

Various acrylic esters and methacrylic esters can be used as the three components of 1II, but from the viewpoint of foam prevention and dispersion effects, acrylic esters or methacrylic esters having an alkyl group having 1 to 8 carbon atoms are preferred. , and belonging to these are:
Methyl acrylate.

Methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, isobutyl acrylate, isobutyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate,
etc.

The 1-1 copolymer of the present invention has the above three components as its constituent components, but in order to provide the copolymer with the high-level dispersion effect targeted by the present invention, the following steps must be taken. It is preferable that it is a composition ratio.

(2) For example, β-ethylenically unsaturated carboxylic acid 50-97.
9% by weight ■ Glycidyl ethers or glycidyl ■ Acrylic ester and/or methacrylic ester 2 to 30% by weight If the composition ratio of the copolymer of the present invention is out of the above range,
There is no significant improvement in dispersibility compared to conventionally used known dispersants, or conversely, the viscosity of the pigment dispersion blended eyelid system increases, or the viscosity increases over time. This is undesirable because phenomena such as the dispersion or the inability to obtain a so-called stable dispersion state are observed.

This becomes the pigment dispersant of the present invention described above. β-ethylenically unsaturated carboxylic acid, which is one of the constituent components of the copolymer, is
From the viewpoint of dispersion effect, it is preferable that the copolymer be in the form of a salt with a cation of 1i1i. Examples of the salt include alkali metal salts (lithium, sodium, potassium salts, etc.), ammonium salts, amine salts, etc. A salt (such as methylamine) may be added, or some unneutralized portion may be left.

The dispersant of the present invention can be used in any of powder, emulsion, aqueous and solvent forms, but it is preferably used in an aqueous form.

The copolymer used as the dispersant of the present invention can be easily obtained by a conventional polymerization method of vinyl monomers.

To give an example, three kinds of components which are polymerizable monomers which are the constituent components of the dispersant of the present invention mentioned above, and one ordinary polymerization initiator.
For example, it can be easily obtained by polymerizing with a water-soluble solution such as potassium persulfate for about 1 to 10 hours, and after the polymerization is completed, adjusting the pH appropriately (for example, pH 7 to 8) with caustic alkali or aqueous ammonia. In addition, in order to improve the dispersion effect as a dispersant, the copolymer of the present invention preferably has a degree of polymerization in the low molecular region, and has a viscosity of <2000 centipoise when made into a 40% by weight aqueous solution. Below (B type viscometer 25℃, rotor rotation speed 6
0rpw) is preferable.0 The powder shows an excellent fractional effect on various pigments for coated paper such as satin white and calcium carbonate. In one example, it is also possible to use it in combination with sodium polyacrylate, sodium tripolyphosphate, etc.

The amount of the dispersant used in the present invention is determined by the amount of the copolymer.

0.05-5% based on pigment, preferably o, i-2
% is sufficient.

The pigment dispersant of the present invention is particularly suitable for dispersing coating materials, but also for fiber processing and building material processing.

It can be widely applied in fields such as paints and ceramics.

The present invention will be specifically explained below with reference to Examples and Comparative Examples.0 Among them, % 1 part indicates the weight basis.Example t The addition reaction product of tacrylic acid was Using azobisisobutyronitrile as the agent, polymerization is carried out in an inpropatol by a conventional method, and after the polymerization is completed, most of the inpropatol is removed by sifting.

Next, water was added so that the content of the copolymer was 40%, and then a trace amount of remaining impropatul was removed. followed by 45% caustic soda at 800 cps).

Using the solution thus obtained as a dispersant, a paint for coated paper was prepared, and its viscosity stability was measured.

That is, clay/heavy calcium carbonate/dispersant/starch/8
BR Latex/Water = 60/40'10.2/10/
10 parts (each using a composition based on solid content).

A 60% solids paint was prepared. In addition, in case of crosstalk,
First, a slurry of heavy calcium carbonate was made with a dispersant and water, and after clay was added to this slurry, 20% modified starch was first added, and then 50% SBR latex was added and kneaded. The viscosity of the distribution surface layer thus obtained was -8 after -8 and 70 after -8.
The viscosity was measured after heating at C for 1 hour.The results are as shown in another report.1 The dispersant of the present invention is effective in reducing the viscosity of high solids paints, and the resulting paints It also has excellent viscosity stability.

[Example 2. Kan 4.5.47] Types and composition ratios of monomer components shown in Attached Table 1.

A dispersant of the present invention was obtained by the same polymerization operation as shown in Example 1 using the following. (Examples 2, 44, 5, 6.7).

In addition, a compounded paint was prepared in the same manner as in Example 1, and the dispersibility meter was effective, and the resulting paint had excellent viscosity stability. Using the type and composition ratio,
By the same polymerization procedure as shown in Example 1.

O obtained a dispersant outside the scope of the present invention (Comparative Example 1.2).

Compared to the dispersant of the present invention (Examples 1 to 7), if a dispersant outside the scope of the present invention (Comparative Examples 1 to 2) is used, the viscosity of the blended paint may be higher, or the viscosity stability of the paint may be lower. Inferior.

(Besshu complex abbreviation) EA Ethyl acrylate BA Butyl acrylate MMA Methyl methacrylate I BMA
Isobutyl methacrylate Patent Applicant Name: Takuya Sosei Chemical Industry Co., Ltd.

Claims (1)

[Claims] 1. A pigment dispersant comprising a copolymer containing the following three components or a salt of the copolymer. ■ -2β-Ethylenically unsaturated carboxylic acid■ Glycidyl ethers or glycidyl esters [:g, β-
Addition reaction product of ethylenically unsaturated carboxylic acid Acrylic acid ester and/or methacrylic acid ester