JPH0441510A - Production of new copolymer latex - Google Patents

Abstract

PURPOSE:To produce a new copolymer latex improved in adhesiveness and being useful for paper coating, carpet backing, etc., by emulsion-copolymerizing a conjugated diene with an ethylenically unsaturated carboxylic acid and another monomer, in the presence of a specified chain transfer agent. CONSTITUTION:40-60wt.% monomer mixture of a particle diameter of 0.05-1mum comprising 20-90wt.% conjugated diene (e.g. butadiene), 0.5-10wt.% ethylenically unsaturated carboxylic acid (e.g. itaconic acid) and another comonomer (e.g. styrene) is emulsion-copolymerized at 60-90 deg.C in a solvent in the presence of 0.2-10 pts.wt., per 100 pts.wt. monomer mixture, chain transfer agent which comprises a hydroxylated (di)sulfide (e.g. 2-hydroxyoctyl ethyl sulfide) and may optionally contain another known chain transfer agent, a surfactant and a polymerization initiator.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a novel copolymer latex used for paper coating, carpet backing, fiber bonding, or adhesives.

[Conventional technology]

Conventionally, the synthetic copolymer latex has been widely used, for example, as a binder for paper coating, a binder for carpet back sizing, a binder for binding fibers such as nonwoven fabrics and artificial leather, and 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 pigments such as kaolin clay, calcium carbonate, satin white, talc, and titanium oxide on the surface of the base paper to improve printability and optical properties such as gloss. , copolymer latex as their binder and starch, polyvinyl alcohol as water-retaining side or auxiliary binder,
It is coated with a paint whose main constituent is a water-soluble polymer such as carboquine methylcellulose, and conventionally, styrene butadiene is made by emulsion polymerization of styrene and butadiene as main monomer constituents. Gen-based copolymer latex, so-called SB-based latex, is commonly used as a binder.

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 towards 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. Moreover, this big strength performance is also related to other print properties, namely wet pick strength,
Since there is a negative correlation with blister resistance, halftone dot reproducibility, etc., there is a growing need for improvements that balance these physical properties to a high level.

Since these properties of coated paper are particularly strongly dependent on the design of the SB latex used as a pigment binder, various studies have been made on the performance of the SB latex.

For example, it has been confirmed that the proportion of the insoluble portion of a copolymer latex film in solvents such as benzene, toluene, and tetrahydrofuran is a controlling factor in pick strength and blister resistance, so various studies have been conducted from this aspect. Specifically, it has been proposed that excellent performance can be achieved by adjusting the composition and gel fraction of the copolymer in Vetex to a specific range (Japanese Patent Publication No. 59-3598). (Japanese Patent Publication No. 60-17879, Japanese Patent Application Laid-open No. 58-4894). The gel fraction of this latex varies depending on various polymerization factors such as monomer composition and polymerization temperature, but a common and simple method for adjusting it to a desired level is to add a chain transfer agent.

Conventionally, halogenated hydrocarbons such as carbon tetrachloride, alkyl mercaptans such as n- or n-dodecyl mercaptan, sulfides, and the like have been used as chain transfer agents.

However, for boat fishing, the pick strength of coated paper is highest when the gel fraction is in the range of 75 to 95% by weight for SB latex, whereas the blister resistance is lower as the gel fraction is lower. It is recognized that it will be good,
None of the above techniques is fully satisfactory in order to simultaneously improve both pick strength and blister resistance to a high level.

In addition, 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 pick strength.
It was difficult to maintain this deleterious property at a high level at the same time.

In addition, good halftone dot reproducibility and super calendar stain resistance during coated paper production are particularly important for gravure printing paper. However, since this product is designed to have a high butadiene unit fraction, halftone reproducibility has been improved to a sufficient degree without impairing supercalendar stain resistance. not present.

Additionally, carpet back sizing adhesives are generally compositions containing copolymer latex and fillers such as calcium carbonate or aluminum hydroxide, and other additives such as thickeners. This adhesive composition is used in the manufacture of tufted carpets, needle punch carpets, etc., mainly to prevent piles from falling off and to bond with primary base fabrics such as jute. Therefore, in this case, improving adhesive strength, which is the most important physical property of carvent, is one of the biggest technical challenges in this industry, and therefore, improvements are being considered from the aspect of blending copolymer latex and compositions. However, the reality is that a satisfactory level has not been obtained so far.

Furthermore, adhesives have traditionally been manufactured by dissolving natural rubber, synthetic rubber, etc. in an organic solvent, coating it on a base material, and evaporating the organic solvent. Due to hygiene issues, there is increasing momentum to use polymer aqueous dispersions (latex) using water as a dispersion medium, and aqueous dispersions of rubber-tackifying resin combinations are being developed (Japanese Patent Publication No. 5728545, JP-A-55-48270, JP-A-58-160378, JP-A-58-
183771).

The aqueous dispersion containing the synthetic rubber latex and the tackifying resin generally has a composition in which 50 to 100 parts by weight of the tackifying resin is added to 100 parts by weight of the solid content of the latex, and the composition is 20 to 23°C. Although it exhibits good adhesive properties at the measurement temperature of 0°C, a satisfactory value for adhesive strength at a temperature of 0°C has not been obtained. In addition, there have been proposed products in which adhesive properties can be obtained only by using a rubber latex polymer without the presence of a tackifying resin (Japanese Patent Application Laid-Open Nos. 56-145909 and 57-57707).

However, this material has the drawback of extremely low adhesion to polyethylene.

[Problems to be Solved by the Invention] As described above, the conventional technology cannot cope with the further increase in printing speed of coated paper, and it is difficult to cope with the need for a binder that enables the production of high-quality coated paper. At present, there is a strong demand for the emergence of copolymer latex. Furthermore, copolymer latexes with high adhesive strength are similarly desired for carpets and adhesives.

[Means for Solving the Problems] Under these circumstances, the present invention improves the balance between big strength and other performance in coated printing paper, and improves the adhesive strength of carpet hack sizing and adhesives. As a result of various studies aimed at providing a high-performance copolymer latex for achieving the above-mentioned properties, we have found that we have developed a method for emulsion polymerization of conjugated dienes, ethylenically unsaturated carboxylic acids, and other monomers copolymerizable with these. It was unexpectedly discovered that a copolymer latex obtained by using a sulfide and/or disulfide having a hydroxyl group as a chain transfer agent can achieve the above object, and the present invention was completed.

That is, the present invention is characterized in that a sulfide and/or disulfide having a hydroxyl group is used as a chain transfer agent in emulsion polymerization of a conjugated diene, an ethylenically unsaturated carboxylic acid, and other monomers copolymerizable with these. This is a method for producing a copolymer latex.

The present invention will be explained in detail below.

A feature of the present invention is that a sulfide and/or disulfide having a hydroxyl group is used as a chain transfer agent in producing a copolymer latex by emulsion polymerization. Here, the hydroxyl group is preferably located at the β position with respect to the sulfur atom in the compound.

Examples of the chain transfer agent include 2-hydroxyethylmethyl sulfide, 2-hydroxypropylpropylsulfide, 2-hydroxyoctylpropylsulfide,
-Hydroxy 3-methylphthyl isoprobyl sulfide, 2-hydroxylauryl lauryl sulfide, 2-hydroxypropyl (nidoquinethyl) sulfide, di-2-hydroxyoctyl sulfide, di-2-hydroxycetylsulfyl 1゛, di-2-hydroquine lauryl sulfide, 3-hydroxyhexylmethyl sulfide,
(2-hydroxyethoxy)ethyl phthylsulfide,
6-hydroxyoctylbutyl sulfide, di(3-hydroxyhexyl) disulfide, di((2-hydroxyethoxy)ethyl fudisulfide, di(2-hydroxycetyl) disulfide', di(2-hydroxylauryl) disulfide, Di(2-hydroxybutyl) disulfide, di(4-hydroxybutyl) disulfide, di[(2-hydroxyethquin)ethyl] disulfide,
Examples include di(8-hydroxylauryl)disulf<).

The preferred amount of the chain transfer agent used is 0.2 to 10 parts by weight, more preferably 0.2 to 10 parts by weight, based on 100 parts by weight of the monomer.
．． It is 3 to 5 parts by weight.

Moreover, the chain transfer agent can also be used in combination with other well-known chain transfer agents. Examples of other well-known chain transfer agents include thioalkanes such as t-dodecylmercaptan and n-dodecylmercaptan; thioalcohols such as mercaptoethanol and mercaptopropanol; thioalkylcarboxylic acids such as thioglycolic acid and thiopropionic acid. Sulfides such as sulfide and diethyl sulfide
Examples include halogenated hydrocarbons such as carbon tetrachloride and bromoform.

Furthermore, any known method can be used for using the chain transfer agent. i.e. - active part addition method;
There are continuous addition methods, intermittent addition methods, and concentration gradient addition methods in which the addition rate is sequentially changed.

The copolymer latex is obtained by emulsion copolymerization of monomers composed of a conjugated diene, an ethylenically unsaturated carboxylic acid, and other monomers copolymerizable with these.

Conjugated dienes used in the present invention include butadiene, isoprene, 2-chloro-1,3-butadiene, and the like.

The amount used is preferably in the range of 20 to 90% by weight based on the total monomers. Furthermore, in the case of a copolymer latex for coated paper, a more preferable range of this conjugated diene is 20 to
It is 70% by weight.

Examples of ethylenically unsaturated carboxylic acids used in the present invention include monobasic carboxylic acids such as acrylic acid, methacrylic acid, and crotonic acid; dibasic carboxylic acids such as itaconic acid, maleic acid, and fumaric acid; Examples include esters.

The amount of the ethylenically unsaturated carboxylic acid used is preferably in the range of 0.5 to 10% by weight based on the total monomers.

Among the other monomers used in the present invention, aromatic (di)vinyl compounds are most typically and effectively used, followed by (meth)acrylic acid esters, vinyl cyanide compounds, and ethylenic amide monomers. etc. Examples of aromatic (di)vinyl compounds include styrene, α-
Methylstyrene, chlorostyrene, alkylstyrene,
Examples include divinylbenzene. (Meth)acrylic acid esters include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, hydroxyethyl (meth)acrylate, and , glycidyl (meth)acrylate, ethylene glycol di(meth)acrylate, and the like. Examples of vinyl cyanide compounds include acrylonitrile and methacrylonitrile.

Examples of the ethylenic amide monomer include (meth)acrylamide, N-methylol (meth)acrylamide, and the like. In addition, vinyl esters such as vinyl acetate, vinyl chloride, vinyl halides such as vinylidene chloride, ethylenic amine monomers such as aminoethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, and styrene Examples include sodium sulfonate.

The production method of the present invention is produced by a conventionally known normal emulsion polymerization method. - For boat fishing, the polymer concentration ranges from 40 to 60% by weight. The particle size of the copolymer latex can be adjusted by the proportion of surfactant and/or seed latex used, and in general, the higher the proportion used, the smaller the particle size of the produced copolymer latex.

Here, the preferred range of particle diameter is 0.05 to 1 μm, more preferably 0.07 to 0.5 μm.

Examples of surfactants include fatty acid soaps, rosin acid soaps, anionic surfactants such as alkyl sulfonates, dialkylaryl sulfonates, alkyl sulfosuccinates, polyoxyethylene alkyl sulfates, and polyoxyethylene alkylaryl sulfates. : Polyoxyethylene alkyl ether, polyoxyethylene alkylaryl ether, polyoxyethylene sorbitan fat M
There are esters, nonionic surfactants such as oxyethylene oquine propylene bronze copolymers, and cationic surfactants. The surfactant is usually used as an anionic surfactant alone or as a mixed anionic/nonionic system, and its usage ratio based on the total monomers is generally in the range of 0.05 to 2% by weight.

Polymerization initiators required to initiate polymerization are those that initiate addition polymerization of monomers by radical decomposition in the presence of heat or reducing substances, such as water-soluble or oil-soluble beroxonisulfate, peroxide, etc. , azobis compounds, etc. are commonly used. Examples include potassium peroxonisulfate, sodium peroxonisulfate, ammonium peroxonisulfate, hydrogen peroxide, t-butyl hydroperoxide, benzoyl peroxide, 2,2-abbisisobutyronitrile, cumene hydroperoxide, etc. Sulfates are most preferably used. The proportion of the polymerization initiator used is usually 0.2 to 1.5% by weight based on the total monomers. The polymerization temperature is generally in the range of 60 to 90°C, but when it is desired to accelerate the polymerization rate or polymerize at a lower temperature, sodium bisulfite, ascorbic acid or its salts, erythorbic acid or its salts, Rongalite are used. A so-called redox polymerization method can be used in which a reducing agent such as the following is used in combination with a polymerization initiator.

Furthermore, various polymerization regulators are often added as desired. For example, sodium hydroxide,
These include pH adjusting agents such as potassium hydroxide, sodium hydrogen carbonate, sodium carbonate, and disodium hydrogen phosphate, and various chelating agents such as sodium ethylenediaminetetraacetate.

The use of the copolymer latex produced according to the invention as a binder for paper coatings can be carried out in the usual manner. That is, in this embodiment, a copolymer latex is mixed with an inorganic pigment and/or an organic pigment in water in which a dispersant is dissolved, a water-soluble polymer, and various additives to form a uniform dispersion. This paint can be applied to the base paper using a conventional method such as various blade coaters or roll coaters.

[Example] Hereinafter, 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.

(a) Blister resistance Using an R1 printing tester (manufactured by Mei Seisakusho), a printing ink (Webb Zett yellow, manufactured by Dainippon Ink Co., Ltd.) 0.3M1 was printed on both sides of the coated paper. 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 changing the temperature of the thermostatic chamber, and the degree of blistering is compared.

The evaluation was performed using a 10-point evaluation method, and the better the blister resistance, the higher the score.

(b) Using a dry pick strength Rr printing tester, print ink (SD Super Deluxe 50 Beni B; tack value 18, manufactured by Shuso Shiki Co., Ltd.) 0
．． 4d Overprint 5 times, trace the pinking that appears on the rubber roll onto another mount, and observe the degree of pinking. The evaluation was performed using a 10-point evaluation method, and the fewer the picking phenomenon, the higher the score.

Examples and Comparative Examples 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, and 70 parts by weight of water was added. 1 part by weight, 0.2 parts by weight of sodium lauryl sulfate, and 2.5 parts by weight of itaconic acid, the internal temperature was raised to 80°C, and then an oily mixture consisting of the monomers and chain transfer agent shown in Table 1, An aqueous solution consisting of 15 parts by weight of water, 1 part by weight of sodium beroxonisulfate, 0.2 part by weight of sodium hydroxide, and 0.1 part by weight of sodium lauryl sulfate was added at a constant flow rate over 4 hours and 5 hours, respectively. After maintaining the temperature at 80°C for one hour, it was cooled, and the pH of the resulting copolymer latex was adjusted to 7 with sodium hydroxide, and unreacted monomers were removed using a steam stripping method. and filtered through a filter cloth with a mesh size of 75 μm. Note that all copolymer latexes were adjusted so that the final solid content concentration was 50% by weight.

Application Examples The copolymer latexes prepared in Examples and Comparative Examples were evaluated for their performance as binders for paper coating. The results are shown in Table 4.

The coating material 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.

From Table 4, it is understood that the coated paper using the copolymer latex of the present invention as a binder has a high balance of bulk strength and other physical properties.

Table 1 1) Manufactured by Enkelhart, product name: Ultra White 9
02) Manufactured by Enkelhart, product name: Ultra Coat 3
) Manufactured by Sankyo Seifun Co., Ltd., product name: Niscalon #15004) Manufactured by Toagosei Kagaku Co., Ltd., product name Niscalon T-405) Manufactured by Sumitomo Chemical Co., Ltd., product name: Sumirets 6366) Manufactured by Nippon Shokuhin Kogyo Co., Ltd., product name: M34600 ~ (below) Margin) Table 2 1) Manufactured by Enkelhart, product name: Ultra White 9
02) Manufactured by Enkelhart, product name: Ultra Coat 3
) Manufactured by Sankyo Seifun Co., Ltd., product name: Niscalon #15004) Manufactured by Toagosei Kagaku Co., Ltd., product name Niscalon T-405) Manufactured by Sumitomo Chemical Co., Ltd., product name: Sumirets 6366) Manufactured by Nippon Shokuhin Kogyo Co., Ltd., product name: MS4600 (Left below margins) ) [Effects of the Invention] According to the present invention, a high-performance copolymer that can further improve the balance between bulk strength and other properties in coated printing paper, and the adhesive strength in carpet puncture sizing and adhesives. Latex can be easily obtained.

Patent applicant: Asahi Kasei Industries, Ltd. teenager Reason Man Watari side male

Claims (1)

[Claims] A copolymer characterized in that a sulfide and/or disulfide having a hydroxyl group is used as a chain transfer agent in emulsion copolymerization of a conjugated diene, an ethylenically unsaturated carboxylic acid, and other monomers copolymerizable with these. Latex manufacturing method