JPH0472312A - Novel copolymer latex - Google Patents

Abstract

PURPOSE:To obtain the subject latex giving a coated printing paper having balanced pick strength and other properties by using a specific alpha, beta-unsaturated nucleus-substituted aromatic monomer, a conjugated diene monomer and an ethylenically unsaturated carboxylic acid monomer as essential components. CONSTITUTION:The objective latex contains, as essential components, (A) an alpha, beta-unsaturated nucleus-substituted aromatic monomer of formula (R, R' and R'' are H, alkyl or hydroxyalkyl; X is H or acyl; 1<=n<=5) (e.g. o- hydroxystyrene), (B) a conjugated diene monomer (e.g. butadiene) and (C) an ethylenically unsaturated carboxylic acid monomer [e.g. (meth)acrylic acid]. The amounts of the components A, B and C are preferably 5-60wt.%, 20-70wt.% and 0.5-10wt.%, respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a synthetic copolymer latex for binders having excellent physical properties in adhesive applications.

More specifically, the present invention relates to a high-performance synthetic copolymer latex suitable for use as a binder for paper coating, carpet bank sizing, fiber bonding, etc., or as an adhesive.

[Conventional technology]

Conventionally, synthetic copolymer latexes have been used as, for example, binders for paper coating, binders for carpent thickening,
It is widely used as a binder for binding fibers such as nonwoven fabrics and artificial leather, and as an adhesive for various materials.

When a copolymer latex is used for such purposes, it is required that the copolymer latex has high adhesive strength and is excellent in water resistance, blistering resistance due to dry heating, and the like.

For example, coated paper uses kaolin clay, calcium carbonate, satin white,
Pigments such as talc and titanium oxide, copolymer latex as a binder, starch as a water-retaining agent or auxiliary binder, and a coating of rice grains whose main components are water-soluble polymers such as polyvinyl alcohol and carboxymethyl cellulose were applied. Conventionally, the copolymer latex is a styrene-butadiene copolymer latex obtained by emulsion polymerization of styrene and butadiene as main monomer components, so-called SB-based lunks. Used for general purposes.

Incidentally, in recent years, the production of coated paper has increased significantly as demand for color-printed magazines, pamphlets, and advertisements has increased. In particular, with the trend toward higher speed printing in offset printing, the quality requirements for coated paper and pigment binders are becoming increasingly sophisticated. There is a strong need for improvement. Furthermore, since this shock strength performance has a negative correlation with other print properties, such as wet shock strength, blister resistance, halftone dot reproducibility, etc., further improvements are needed to balance these physical properties to a high level. requested.

These properties of coated paper are particularly strongly dependent on the performance of the SB-based launx used as a pigment binder, so various studies have been made on the performance of the SB-based launx. .

For example, it has been confirmed that the proportion of the insoluble portion of the copolymer latex film in solvents such as Hensen, toluene, and tetrahydrofuran is the controlling factor for the shock strength and blister resistance. Specifically, by adjusting the composition and gel fraction of the copolymer in the latex to a specific range,
It has been proposed to exhibit excellent performance (Japanese Patent Publication No. 593598, Japanese Patent Publication No. 60-17879,
(Japanese Patent Application Laid-open No. 1984-894).

It is also known that a copolymer latex with excellent bulk strength and blister resistance can be obtained by using a water-soluble organic solvent inert to the polymerization reaction in the polymerization process (JP-A-63235593). In this case, since a large amount of the organic solvent is used, the resulting latex has the disadvantage of poor mechanical stability, and does not fully satisfy the above-mentioned required performance.

Furthermore, since the optimal butadiene unit fraction for wet pick strength in offset printing is 34% by weight or less, which is different from the optimal butadiene unit fraction for pink strength, it is necessary to simultaneously achieve high levels of both physical properties. was difficult.

On the other hand, for gravure printing paper, good halftone dot reproducibility and supercalendar stain resistance during coated paper production are particularly important, and for example, good binders for gravure printing paper have been proposed (JP Since this product is designed to have a high butadiene unit fraction, the halftone dot reproducibility is improved to a sufficient degree without impairing the super calender stain resistance. has not yet been achieved.

Regarding the following monomer (1), p-acetoxostyrene, which is one of the RCH- and S-OX) n, , There is an example where (
(U.S. Pat. No. 4,822,862).

[Problem to be solved by the invention]

Under these circumstances, the present invention aims to improve the balance between pick strength and other properties in coated printing paper, as well as the adhesive strength of carpet hack sizing and adhesives. It was developed for the purpose of capturing and supplying copolymer latex.

[Means for Solving the Problems] As a result of intensive research to develop the above-mentioned high-performance copolymer latex, the present inventors found that α, β-
Unsaturated nuclear-substituted aromatic monomer (A), conjugated diene monomer (B), and ethylenically unsaturated carboxylic acid monomer (
The present inventors have discovered that by including C) as an essential component, a copolymer latex with low viscosity and excellent adhesive properties can be obtained, and the present invention has been completed.

The present invention will be explained in detail below.

The α,β-unsaturated nuclear-substituted aromatic monomer (A) represented by the following general formula (1) used in the present invention is an essential component for increasing the adhesive strength of the copolymer latex. Specifically, 0-hydroxystyrene (HS), m-
Examples include hydroxystyrene, P-hydroxystyrene, 0-acetoxystyrene, m-acetoxystyrene, p-acetoxystyrene, 4-hydroxy-2-methylstyrene, and 2-hydroxy-4-methylstyrene.

(In the formula, R, R' or R'' is H1 alkyl or hydroxylalkyl, and X represents H or acyl, and is an integer of 1≦n≦5) the above α, β-unsaturated nuclear substitution The amount of the aromatic monomer (8) to be used is 0.00% on the basis of all monomers.
It is preferably in the range of 1 to 90% by weight. Furthermore, when providing a copolymer latex for coated paper, a more preferable range of α,β-unsaturated nuclear substituted aromatic monomer (A) is 5
~60% by weight.

Examples of the conjugated diene monomer (B) used in the present invention include butadiene, isoprene, 2-chloro-1,3
-butadiene, pentagene, etc.

These conjugated diene monomers (B) may be used alone or in combination of two or more, and the amount used is 5% by weight or more based on the weight of the total monomers. , preferably in the range of 20 to 70% by weight from the viewpoint of cohesive force.

Examples of the ethylenically unsaturated carboxylic acid monomer (C) used in the present invention include monocarboxylic acids such as acrylic acid, methacrylic acid, and crotonic acid, and dicarboxylic acids such as maleic acid, itaconic acid, and fumaric acid. Or its acid anhydride, monoalkyl ester, etc. are used.

These ethylenically unsaturated carboxylic acid monomers (C) may be used alone or in combination of two or more, and the amount used is based on the weight of the total monomers. The content is 0.1% by weight or more, preferably in the range of 0.5 to 10% by weight in view of the balance with viscosity.

Other monomers copolymerizable with these (^), (B) and (C) monomers include, for example, styrene, α-methylstyrene, 4-methylstyrene, 2-hydroxymethylstyrene, 4-ethyl Styrene, 4 ethoxystyrene, 3
．． Aromatic styrene derivatives such as 4-dimethylstyrene, 2-chlorostyrene, 4-chloro-3-methylstyrene, 214-dichlorostyrene, divinylhenzene, methyl acrylate, ethyl acrylate, probyl acrylate, butyl acrylate, 2- Acrylic acid esters such as ethylhexyl acrylate and hydroxyethyl acrylate, methacrylic acid esters such as methyl methacrylate, ethyl methacrylate, proyl methacrylate, butyl methacrylate, vinyl cyanide monomers such as acrylonitrile and methacrylateril, acrylamide, Amides such as methacrylamide and N-methylolacrylamide, glycidyl acrylate, glycidyl methacrylate, etc. are used.

The copolymer latex of the present invention has the following properties in an aqueous medium:
It is obtained by emulsion polymerization of the α,β-unsaturated nuclear-substituted aromatic monomer, a conjugated diene compound, and another monomer copolymerizable with the ethylenically unsaturated carboxylic acid. There are no particular restrictions on this emulsion polymerization method, and conventionally known methods can be used, for example, using water, the above-mentioned monomers, a chain transfer agent, a surfactant, a radical polymerization initiator, and other additive components used as necessary. In a dispersion system having as a basic component, a method is used in which the monomer is polymerized to produce an aqueous dispersion of copolymer particles, that is, a copolymer latex. The concentration of the copolymer in this copolymer latex is usually 4
It is selected in the range of 0 to 60% by weight, and its average particle size is 0.05 to 1 μm, preferably 0.07 to 0.5 μm.
It is advantageous to have a range of . The average particle size can be adjusted by adjusting the proportion of surfactant and seed latex used, and generally, the higher the proportion used, the smaller the average particle size of the resulting copolymer latex tends to be.

Examples of the chain transfer agent that can be used include t-dodecylmercaptan, thioglycolic acid, bromoform, and carbon tetrachloride.

Examples of the surfactant include anionic surfactants such as fatty acid soap, rosin acid soap, alkyl sulfonate, dialkylaryl sulfonate, alkyl sulfosuccinate, polyoxyethylene alkyl sulfate, and polyoxyethylene alkylaryl sulfate. Examples include activators, nonionic surfactants such as polyoxyethylene alkyl ether, polyoxyethylene alkylaryl ether, polyoxyethylene sorbitan fatty acid ester, and oxyethylene oxypropylene block copolymer. This surfactant is usually used as an anionic surfactant alone or as an anionic/nonionic mixed system.
The amount used is based on the weight of all monomers, and is usually 0.05~
It can be selected within the range of 2% by weight.

The radical polymerization initiator has the effect of causing addition polymerization of monomers by radical decomposition using heat or a reducing substance. Examples of such a radical polymerization initiator include water-soluble or oil-soluble beroxonisulfuric acid. Salts, peroxides, azobis compounds, etc., specifically potassium beroxonisulfate, sodium berooxodisulfate, ammonium beroxonisulfate, hydrogen peroxide, t-butyl hydroperoxide, hendiyl peroxide, 2,2-azobisisobutyronitrile , cumene hydroperoxide, etc.
Among these, peroxonisulfate is particularly preferred. The amount of the polymerization initiator used is usually selected within the range of 0.2 to 1.5% by weight based on the weight of all monomers.

The polymerization temperature in this emulsion polymerization is usually 60 to 90°C.
However, if it is desired to accelerate the polymerization rate or polymerize at a lower temperature, a reducing agent such as acidic sodium sulfite, ascorbic acid or its salts, erythorbic acid or its salts, or longalisotho may be combined with the polymerization initiator. The so-called Retox polymerization method, which is used in

In the present invention, various polymerization regulators may be used as desired, such as pH 3 regulating agents such as sodium hydroxide, potassium hydroxide, sodium hydrogen carbonate, sodium carbonate, and disodium hydrogen phosphate, and various chelates such as sodium ethylenediaminetetraacetate. can be added.

When the copolymer latex of the present invention is used as a binder for paper coatings, it can be prepared using a conventional method such as adding an inorganic pigment or inorganic pigment to water in which a dispersant is dissolved.
A method can be adopted in which the copolymer latex is added and mixed together with organic pigments, water-soluble polymers, and various additives to form a homogeneous dispersion. This paper coating paint can be applied to base paper by a conventional method using various blade coaters, roll coaters, etc.

〔Example〕

Next, the present invention will be explained in more detail with reference to Examples.
The present invention is not limited in any way by these examples.

In addition, each characteristic was calculated|required as follows.

(1) Properties of copolymer latex (a) Average particle size Light scattering particle size analyzer (manufactured by CN UNOTO, Model 60)
The average particle diameter of the copolymer latex was measured using the following method.

(b) Viscosity (25''C) Using a B-type viscometer, measurement was performed using a No. 2 rotor at 60 rpm with a 6-trowel.

(2) Paper coating performance (a) Blister resistance R1 printing tester (manufactured by Mei Seisakusho) was used to print 0.3 cc of printing ink (manufactured by Dainippon Ink Co., Ltd., Webb Zett yellow) on both sides of the coated paper. print. This printed coated paper is cut to an appropriate size, and the test piece is immersed in a silicone oil constant temperature bath adjusted to a predetermined temperature to observe whether or not blisters occur. This test is performed by varying the temperature of the thermostatic chamber, and the lowest temperature at which blistering is observed is determined. The higher the temperature, the better the blister resistance.

(TJ) Using a dry pick strength R1 printing tester, print ink (manufactured by Kana Shiki Co., Ltd., SD Susu--Deluxe 50 Beni B; tack value 18)
0.4 cc Overprinting is performed 5 times, and the picking state that appears on the rubber roll is reversed onto another mount and the extent of the picking is observed.

The evaluation was performed visually, and the less the pinking phenomenon was, the better it was (◎), and as the pinking phenomenon increased, it was expressed as O→△.

(c) Using a wet pick strength R1 printing tester, the surface of the coated paper was moistened with a water absorbing roll, and then printing ink (manufactured by Kansai Shiki Co., Ltd., SD Susu Deluxe 50 Beni B; tack value 18) was applied. 4 cc is printed once, the pinking state that appears on the rubber roll is traced onto another mount, and the extent of the pinking is observed. The evaluation was performed visually, and the fewer the picking phenomena, the better (◎), and as the number of picking phenomena increased, it was expressed as ○ → △.

Examples 1 to 5 and Comparative Examples 1 to 5 4 parts by weight of an aqueous dispersion of seed particles with a diameter of 0.04 μm (solid content concentration 25% by weight) was placed in a pressure-resistant reaction vessel equipped with a stirring device and a temperature control jacket. Further, 70 parts by weight of water, 0.2 parts by weight of sodium lauric sulfate, and 2.5 parts by weight of fumaric acid were added, the internal temperature was raised to 80°C, and then the monomers and chain transfer agent shown in Table 1 were added. and an aqueous solution consisting of 15 parts by weight of water, 1 part by weight of sodium beroxonisulfate, 0.2 parts by weight of sodium hydroxide, and 0.1 part by weight of sodium lauric sulfate, for 4 hours and 5 hours, respectively. Addition was made at a constant flow rate. The temperature was maintained at 80°C for 1 hour, then cooled, and the resulting copolymer latex was adjusted to pH 7 with sodium hydroxide, and unreacted monomers were removed by steam stripping. , 200 mesh filter cloth.

Note that all copolymer latexes were adjusted so that the final solid content concentration was 50% by weight.

The average particle diameter and viscosity of these copolymer latexes are
Shown in the table.

Table 1 (blank below) Application Example 1 The copolymer Latinx prepared in Examples 1 to 5 and Comparative Examples 1 to 5 was evaluated for its performance as a paper coating binder. The results are shown in Table 1.

The coating composition had the formulation shown in Table 2, and was prepared using a high-speed stirrer with an amount of water that gave a nonvolatile content concentration of 63% by weight. The pH of the paint was adjusted to 9.0 with aqueous ammonia. Table 3 shows the conditions for preparing coated paper using this paint.

Table 2 (Note) 1) “Ultra White 90” manufactured by Engelhard
” “Ultra Coat” manufactured by Engelhard Co., Ltd. “
Niscalon # 1500 J Toagosei Kagaku Co., Ltd. “Aron T~40” Sumima Kagaku Co., Ltd. “Sumiretsu 636” Nihon Shokuhin Kako Co. r MS4600 J No. 3
Table [Effects of the Invention] According to the present invention, a high-performance copolymer is provided which can further improve the balance between adhesive strength and other properties in coated printing paper, and the adhesive strength in carpet hack sizing and adhesive peeling. Polymer latinx can be easily obtained.

Patent applicant: Asahi Kasei Industries, Ltd.

Claims (1)

[Claims] 1. A, Formula (I): ▲ Numerical formulas, chemical formulas, tables, etc. ▼ (I) (In the formula, R, R' or R'' is H, alkyl or hydroxylalkyl, represents H or acyl and is an integer of 1≦n≦5); B, a conjugated diene monomer; and C, ethylene; A novel copolymer latex characterized by containing as essential components at least three kinds of unsaturated carboxylic acid monomers.