JP2000154496A - Copolymer latex for coating paper and composition for coating paper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain both a copolymer latex capable of remarkably improving surface strength and blister resistance of a coated paper, excellent in white paper gloss and printing gloss, improved in mechanical stability and stickiness preventing properties, excellent in coating operation efficiency and suitable for coating a paper, especially coating of a printing paper for high-speed rotary offset printing and a composition for coating the paper using the copolymer latex. SOLUTION: This composition for coating a paper is obtained by carrying out an emulsion polymerization of (a) 10-80 pts.wt. of a conjugated diene-based monomer, (b) 0.5-15 pts.wt. of an ethylenically unsaturated carboxylic acid monomer and (c) 5-89.5 pts.wt. of other monomers copolymerizable with the monomers (a) and (b) [in which the total amount of the monomers (a), (b) and (c) is 100 pts.wt.] in an aqueous medium and has >=80 wt.% toluene-insoluble content. The composition for coating the paper uses the copolymer latex.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a latex suitable for paper coating, and more particularly, to an excellent coating stability such as mechanical stability and non-stickiness, adhesive strength, blister resistance, and gloss of white paper. The present invention relates to a co-loading base latex having excellent printing gloss and suitable for paper coating, particularly for coating high-speed offset rotary printing paper.

[0002]

2. Description of the Related Art Conventionally, a paper coating composition mainly comprising a pigment and an aqueous binder has been applied to paper to produce a coated paper excellent in printability. Copolymer latex has been used as a main binder in paper coating compositions due to its excellent adhesive strength.

In recent years, as printing has become more sophisticated and faster,
The performance required for coated paper is also becoming severer, and improvements such as anti-stick properties, blister resistance, white paper gloss, and print gloss have come to be required. Further, in recent years, there has been an increasing demand for reducing the amount of the binder for the purpose of cost reduction. For this reason, there has been a demand for a binder exhibiting sufficient surface strength even with a smaller amount of addition.

[0004] In addition, the production speed of coated paper itself has been increased, and the coating operability has been improved, and particularly, the generation of agglomerates and roll fouling, which are the main obstacles, have been improved. Reduction (stickiness prevention) is also strongly required.

[0005] Copolymer latex is required to improve the above-mentioned properties, especially the surface strength. For this purpose, for example, a method for adjusting the gel content of the copolymer or a method for improving the composition of the copolymer is required. Has been proposed. However, the surface strength and other properties often conflict with each other, and it is very difficult to balance all the properties to a high level.

For example, in order to improve the adhesive strength, a method of increasing the amount of a conjugated diene monomer to lower the glass transition point of a copolymer has been attempted. The property of preventing tackiness is significantly reduced.
Conversely, when the glass transition point is increased, the mechanical stability, water resistance, and rigidity are good, but the adhesive strength and print gloss are significantly reduced. In the method using a large amount of a monomer having a functional group, the adhesive strength is improved, but the viscosity of the latex becomes abnormally high, so that the workability is significantly reduced.

As described above, none of these methods can satisfy the requirements for all the characteristics even if the improvement of any of the characteristics is achieved, and satisfy the increasingly severe requirements in printing. Is not possible at present.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to significantly improve the surface strength and blister resistance of a coated paper, and to provide excellent white paper gloss and print gloss, as well as mechanical stability and non-stickiness. Improved coating operability for paper coating,
In particular, it is an object of the present invention to provide a co-body base latex suitable for coating high-speed offset rotary printing paper. Another object of the present invention is to provide a paper coating composition using the above copolymer latex.

[0009]

According to the present invention, the above-mentioned object of the present invention is achieved by providing the following copolymer latex for paper coating. (1) (a) 10 to 80 parts by weight of a conjugated diene monomer,
(B) 0.5 to 15 ethylenically unsaturated carboxylic acid monomers
(C) 5 to 89.5 parts by weight of (c) another monomer copolymerizable with the (a) conjugated diene monomer and (b) the ethylenically unsaturated carboxylic acid monomer. ,
(A), (b) and (c) are copolymers obtained by emulsion polymerization in an aqueous medium, and the toluene-insoluble content is 80% by weight or more. Characteristic copolymer latex for paper coating. (2) In the molecular weight distribution obtained by gel permeation chromatography of the copolymer, the proportion of components detected earlier than the elution time corresponding to 1.1 million in terms of polystyrene equivalent molecular weight is 50% or more. The copolymer latex for paper coating according to the above (1), which is characterized in that: (3) The copolymer latex for paper coating according to the above (1) or (2), which is used for coated paper for offset rotary printing. (4) 100 parts by weight of a pigment comprising 30 to 100% by weight of calcium carbonate and 0 to 70% by weight of a pigment other than calcium carbonate (the total of both is 100% by weight); A paper coating composition comprising the copolymer described in (1). (5) The composition for paper coating according to the above (4), which is used for coated paper for web offset printing.

The copolymer latex for paper coating of the present invention comprises:
When the toluene-insoluble content is 80% by weight or more in terms of solid content, the above-mentioned target performance of the present invention can be obtained. That is, the copolymer latex of the present invention,
Since the toluene-insoluble content is 80% by weight or more, for example, during high-speed printing, it has resistance to extremely large deformation,
For this reason, it has high adhesive strength. Furthermore, since the air permeability in the coating layer is kept moderate, the blister resistance is also excellent. In addition, the copolymer latex of the present invention has a large amount of toluene-insoluble components and therefore has only a low molecular weight component, and is excellent in mechanical stability and non-stickiness. Furthermore, since the white paper gloss is good and the solvent resistance is high, it has high print gloss. As described above, the blister resistance, the mechanical stability, and the printing gloss are mutually contradictory performances so far, and these cannot be compatible. The polymer latex made it possible to achieve both.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The copolymer latex for paper coating of the present invention will be described in detail.

Specific examples of the (a) conjugated diene monomer used for the production of the copolymer latex for paper coating include butadiene, isoprene, 2-chloro-1,3-butadiene and 2-methyl-1. , 3-butadiene and the like. These can be used alone or in combination of two or more. Of these, butadiene is particularly preferred.

(A) The amount of the conjugated diene monomer used is selected from the range of 10 to 80 parts by weight, preferably 20 to 75 parts by weight, based on 100 parts by weight of all the monomers.
If the amount is less than 10 parts by weight, sufficient adhesive strength cannot be obtained, while if it exceeds 80 parts by weight, water resistance and adhesive strength are undesirably reduced.

The (b) ethylenically unsaturated carboxylic acid monomer which can be used for producing a copolymer latex for paper coating, or (b) the ethylenically unsaturated carboxylic acid when emulsion-polymerized in an aqueous medium. The following can be mentioned as specific examples of those that change into acid monomers. (A) Monocarboxylic acids such as acrylic acid, methacrylic acid and crotonic acid. (B) Dicarboxylic acids such as maleic acid, fumaric acid and itaconic acid. (C) Half esters such as methyl maleate, methyl itaconate and β-methacryloxyethyl acid hexahydrophthalate. (D) The anhydrides of the unsaturated carboxylic acids of the above (a) and (b). For example, acrylic acid anhydride, maleic anhydride, and the like are converted into carboxylic acids during emulsion polymerization in an aqueous medium, and thus can be used as monomers during emulsion polymerization. These can be used alone or in combination of two or more.

Among them, (b) the ethylenically unsaturated carboxylic acid monomer is selected from the group consisting of (b) dicarboxylic acid, (c) half esters thereof, and (d) dicarboxylic anhydride. It is preferable to use at least one kind, and particularly preferable to use (ii) dicarboxylic acid. The ratio (α) of at least one (α) selected from the group consisting of (b) dicarboxylic acid, (c) half esters and (d) dicarboxylic anhydride to (a) monocarboxylic acid (β) / (Β) (molar ratio) is 0/10
0 to 95/5, more preferably 10/90 to 90/1
Desirably, it is 0. When used in this ratio range, the adhesive strength, the latex, and the mechanical stability of the coating liquid containing the latex are excellent.

(B) The amount of the ethylenically unsaturated carboxylic acid monomer used is based on 100 parts by weight of the total amount of the monomers.
It is used in a proportion of 0.5 to 15 parts by weight, preferably 1 to 10 parts by weight. If the amount is less than 0.5 part by weight, the mechanical and chemical stability of the copolymer latex for paper coating will decrease in addition to the adhesive strength, and if it exceeds 15 parts by weight, the copolymer for paper coating will decrease. The viscosity of the latex becomes high, handling becomes difficult, and the operability decreases, which is not preferable.

(C) Other monomers copolymerizable with the (a) conjugated diene monomer and (b) the ethylenically unsaturated carboxylic acid monomer (hereinafter referred to as "(c) other monomer Specific examples of (a) are: (a) ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, hexyl methacrylate, octyl methacrylate, 2-ethyl methacrylate Alkyl or methacrylic acid alkyl esters such as hexyl, lauryl methacrylate, and glycidyl methacrylate; or glycidyl esters, (b) aromatic vinyl compounds such as styrene, α-methylstyrene, vinyltoluene, and p-methylstyrene; C) acrylamide, methacrylamide, N, N-dimethylacrylamide, N-methylolacrylamide; Acrylamide or methacrylamide compounds of the ethylenically unsaturated carboxylic acid, (d)
Carboxylic acid vinyl esters such as vinyl acetate, (e)
Examples thereof include vinyl cyanide compounds such as acrylonitrile, methacrylonitrile, and α-chloroacrylonitrile. These can be used alone or in combination of two or more. Of these, styrene is particularly preferably used as the aromatic vinyl compound, and acrylonitrile is preferably used as the vinyl cyanide compound.

(C) Other monomers are used for imparting appropriate hardness, elasticity and water resistance to the obtained copolymer. The amount used is 5 to 89.5 parts by weight, preferably 10 to 89.5 parts by weight based on 100 parts by weight of the total monomers.
Parts by weight, more preferably from 20 to 84 parts by weight. If the amount is less than 5 parts by weight, the water resistance is poor, while if it exceeds 89.5 parts by weight, the copolymer becomes too hard, and the adhesive strength is undesirably reduced.

The copolymer latex for paper coating of the present invention comprises:
As described above, the toluene insoluble content is 80% by weight or more. The toluene insoluble content of the copolymer latex of the present invention is a value measured as follows. That is, the copolymer latex is adjusted to pH 7.5, coagulated with isopropanol, and the coagulated product is washed with methanol and dried, and then a predetermined amount (about 0.05 g) of a sample is poured into a predetermined amount (100 ml). In toluene for 20 hours. Thereafter, the mixture is filtered with a qualitative filter paper of No. 2, and the weight% based on the total solid content of the remaining solid content on the obtained filter paper is defined as a toluene-insoluble content. The above toluene-insoluble matter can be controlled by the polymerization temperature, the amount of the molecular weight regulator, the method of adding the monomer, and the like. The toluene insoluble content of the copolymer latex in the present invention is 80% by weight or more, preferably 85 to 100% by weight, more preferably 90 to 100% by weight, further preferably 91 to 100% by weight, particularly preferably 94 to 10% by weight.
0% by weight. If the amount of the toluene-insoluble component is less than 80% by weight, the blister resistance or the dry strength is reduced, and the mechanical stability and the stickiness are also reduced.

The copolymer contained in the copolymer latex of the present invention has a molecular weight distribution obtained by gel permeation chromatography (GPC) measurement.
The proportion of components detected faster than the elution time corresponding to 1.1 million in terms of polystyrene equivalent molecular weight is preferably 50 to
It is 95%, more preferably 60 to 95%, further preferably 65 to 95%, particularly preferably 70 to 95%.
110 as the molecular weight in terms of polystyrene in the molecular weight distribution
If the proportion of the component detected faster than the elution time corresponding to 10,000 is 50% or more, the amount of the ultrahigh molecular weight polymer or its crosslinked gel component is relatively large, and the polymer strength is high, so that the adhesive strength appears. In addition, since there are few low molecular weight components, mechanical stability and non-stickiness are also improved. Also,
It is relatively difficult to form a film, and exhibits high blister resistance because it provides appropriate air permeability and deformability of the coating layer. That is, a product excellent in the balance between blister resistance and dry strength and also excellent in other coated paper properties such as white paper gloss and print gloss can be obtained.

In the present invention, in the molecular weight distribution obtained from the measurement of gel permeation chromatography (GPC), the proportion of the component detected faster than the elution time corresponding to 1.1 million in terms of the molecular weight in terms of polystyrene is as follows:
As shown in FIG. 1, in the elution curve with the detection amount on the vertical axis and the elution time on the horizontal axis, when the area surrounded by the elution curve and the horizontal axis is the total area S, the molecular weight in terms of polystyrene is The ratio (ratio) of the area of the component detected earlier than the elution time T1 corresponding to 1.1 million, that is, the ratio of the area S1 of the hatched portion to the total area S in FIG.

In the present invention, GPC is measured under the following conditions. <Preparation of Sample> 1 g of water and about 1 g of a cation exchange resin washed and washed according to a conventional method are added to 0.3 g of a copolymer latex having a solid content adjusted to 48% by weight to remove cations. Then, 50 ml of tetrahydrofuran was added, and 2
Allow time to dissolve. Next, a polytetrafluoroethylene membrane filter (pore size 3 μm, AD
(VANTEC), and the filtrate is used as a measurement sample. <Apparatus, measurement conditions, etc.> Measurement apparatus: HLC-8020 (manufactured by Tosoh Corporation) Type of filler, particle size: polystyrene gel 30 μm GMH HR-H (30) Manufactured by Tosoh Column size: 7.8 mm 2D × 300 mm Solvent : Tetrahydrofuran Sample concentration: 0.3% by weight Injection amount: 30 μl Flow rate: 1 ml / min Temperature: 40 ° C. Detector: Differential refractometer In addition, before measurement, use a polystyrene standard substance with a known molecular weight before calibration. A line was prepared and expressed as a molecular weight in terms of polystyrene.

The proportion of components detected faster than the elution time corresponding to 1.1 million in terms of polystyrene equivalent molecular weight is 50%
The above can be controlled by the polymerization temperature, the amount of the molecular weight regulator, the method of adding the monomer, and the like.

The copolymer latex for paper coating of the present invention comprises:
The above monomers can be produced by a conventionally known emulsion polymerization method. That is, it can be obtained by adding a monomer, a polymerization initiator, an emulsifier, a polymerization chain transfer agent and the like to an aqueous medium (usually water) and performing emulsion polymerization.

The polymerization initiator used in the emulsion polymerization in the present invention is not particularly limited. For example, hydroperoxides such as cumene hydroperoxide, diisopropylbenzene hydroperoxide, paramenthane hydroperoxide, benzoyl peroxide, lauroyl Organic polymerization initiators such as peroxides such as peroxides and azo compounds such as azobisisobutyronitrile; and inorganic polymerization initiators such as persulfates such as potassium persulfate, sodium persulfate and ammonium persulfate. Can be used.

In the present invention, when the organic polymerization initiator is used alone, the obtained copolymer latex has poor mechanical stability and a large amount of coagulated product is generated during the polymerization. It is preferable to use the agent alone or in combination with an organic polymerization initiator.

The above polymerization initiator can be used as a so-called redox polymerization initiator in combination with a reducing agent such as sodium bisulfite.

Among these polymerization initiators, persulfates such as potassium persulfate and ammonium persulfate, or a combination thereof with azobisisobutyronitrile or benzoyl peroxide, or a combination of these with a reducing agent Is preferably used.

The amount of the polymerization initiator used in the present invention is usually 0.1 to 5 parts by weight per 100 parts by weight of the monomer,
Preferably it is 0.5 to 2 parts by weight. When the inorganic polymerization initiator and the organic polymerization initiator are used in combination, the ratio of the organic polymerization initiator is preferably 70% by weight of the total polymerization initiator.
Or less, more preferably 50% by weight or less. If the proportion of the organic polymerization initiator exceeds 70% by weight, problems such as those occurring when the organic polymerization initiator is used alone are not preferred.

The emulsifier used for the emulsion polymerization in the present invention is not particularly limited, and any of anionic, nonionic and amphoteric surfactants can be used. These can be used alone or in combination of two or more. For example, anionic surfactants such as sulfate salts of higher alcohols such as sodium lauryl sulfate, alkylbenzene sulfonates such as sodium dodecylbenzenesulfonate, and sulfonates of aliphatic carboxylic acid esters such as sodium dioctylsulfosuccinate; polyethylene Nonionic surfactants such as an alkyl ester type, an alkyl phenyl ether type, and an alkyl ether type of glycol can be used. Examples of the amphoteric surfactant include those having a carboxylate, a sulfate, a sulfonate, a phosphate, or a phosphate as an anion portion, and an amine salt or a quaternary ammonium salt as a cation portion. Can be mentioned. Specifically, lauryl betaine, stearyl betaine, cocoamidopropyl betaine, and 2-undecylhydroxyethyl imidazolium betaine salts as alkyl betaine salts, and lauryl-β-alanine, stearyl-
β-alanine, lauryldi (aminoethyl) glycine,
Octyl di (aminoethyl) glycine and salts of dioctyldi (aminoethyl) glycine can be mentioned.

Of these emulsifiers, alkylbenzene sulfonates are particularly preferably used. More specifically, sodium dodecylbenzenesulfonate and the like are particularly preferably used. The alkyl benzene sulfonate may be an anionic surfactant such as a sulfate of a higher alcohol or a sulfonate of an aliphatic carboxylic acid ester, or an alkyl ester type, an alkyl ether type or an alkyl ether type of polyethylene glycol. You may use together with nonionic surfactants, such as a phenyl ether type.

The amount of the emulsifier used is usually 0.05 to 2 parts by weight, preferably 0.1 to 2 parts by weight, per 100 parts by weight of the total monomers.
It is 0.5 to 1 part by weight. If the amount of the emulsifier exceeds 2 parts by weight, the water resistance is poor and the foaming of the paper coating composition becomes remarkable, causing a problem during coating. When the alkylbenzene sulfonate is used in combination with another anionic or nonionic surfactant, the proportion of the alkylbenzene sulfonate is preferably 50% by weight or more of the total emulsifier.

In the present invention, the polymerization chain transfer agent used for the emulsion polymerization is not particularly limited, and specifically, for example, octyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, n-hexadecyl mercaptan, mercaptans such as n-tetradecyl mercaptan and t-tetradecyl mercaptan; xanthogen disulfides such as dimethyl xanthogen disulfide, diethyl xanthogen disulfide and diisopropyl xanthogen disulfide; And halogenated hydrocarbons such as carbon tetrachloride and ethylene bromide; carbonized such as pentaphenylethane and α-methylstyrene dimer Motorui; and acrolein, methacrolein, allyl alcohol, 2-ethylhexyl thioglycolate, terpinolene, alpha-terpinene,
γ-terpinene, dipentene, 1,1-diphenylethylene and the like can be mentioned. These can be used alone or in combination of two or more. Among them, mercaptans, xanthogen disulfides, thiuram disulfides, 1,1-diphenylethylene, α-methylstyrene dimer and the like are preferably used.

The amount of the polymerization chain transfer agent used is 100
0 to 20 parts by weight, preferably 0.05 to 1 part by weight,
5 parts by weight, more preferably 0.1 to 10 parts by weight. If the amount of the polymerization chain transfer agent exceeds 20 parts by weight, the adhesive strength is undesirably reduced.

The emulsion polymerization method and the conditions in the present invention are not particularly limited, and can be carried out under conventionally known methods and conditions.

For example, the addition method of the polymerization chain transfer agent may be any of a batch addition method, a division addition method, a continuous addition method, and a combination thereof.

In the case of, for example, two-stage polymerization, the polymerization chain transfer agent may be added to one of the first and second stages, or may be added to both.

The method of adding the monomer may be any of a batch addition method, a split addition method, a continuous addition method, and a combination thereof.

The paper coating composition in which the copolymer latex for paper coating of the present invention is used may comprise an inorganic pigment or an organic pigment, preferably the above copolymer latex alone or, if necessary, an inorganic pigment. Obtained by blending with other binders. The amount of the copolymer latex in the paper coating composition is usually 1 to 30 parts by weight, and preferably 3 to 20 parts by weight, based on 100 parts by weight of the pigment in terms of solid content. The amount of the other binder added as needed is usually 20 parts by weight or less, preferably 0 to 15 parts by weight, based on 100 parts by weight of the pigment in terms of solid content. The pigment preferably contains calcium carbonate as a main component, and the preferred proportion of calcium carbonate in the total pigment is 30 to 100% by weight, more preferably 40 to 100% by weight, and particularly preferably 50 to 100% by weight. It is. The preferred proportion of the pigment other than calcium carbonate is 0 to 70% by weight, more preferably 0 to 60% by weight, and particularly preferably 0 to 50% by weight. Here, the total amount of both is 100% by weight. When the use ratio of calcium carbonate is in the above range, the balance between the physical properties of blister resistance and adhesive strength is further improved.

As inorganic pigments, besides calcium carbonate, kaolin clay, talc, barium sulfate, titanium oxide (rutile anatase), aluminum hydroxide, zinc oxide, satin white and the like are used. As organic pigments, polystyrene latex and the like are used. can do. These can be used alone or in combination of two or more. Specific examples of the calcium carbonate used in the present invention include heavy calcium carbonate and light calcium carbonate. These can be 1 depending on the purpose.
Species can be used alone or in combination of two or more.

Other binders include natural binders such as starch, oxidized starch, soy protein, casein, and the like.
Alternatively, synthetic latex such as polyvinyl alcohol, polyvinyl acetate latex, and acrylic latex can be used.

The paper coating composition using the copolymer latex of the present invention may further contain various commonly used auxiliaries such as dispersants (eg, sodium pyrophosphate and sodium hexametaphosphate) and defoamers. (Polyglycol, fatty acid ester, phosphate ester, silicone oil, etc.), leveling agent (funnel oil, dicyandiamide,
Urea), preservatives, water resistant agents (formalin, hexamine, melamine resin, urea resin, glyoxal, etc.), release agents (calcium stearate, paraffin emulsion, etc.), fluorescent dyes, color retention improvers (carboxymethyl cellulose, Sodium alginate, etc.) can be added as necessary.

The paper coating composition using the copolymer latex for paper coating of the present invention can be applied by a conventionally known method, for example, using an air knife coater, blade coater, roll coater, applicator, or the like. it can.

The copolymer latex for paper coating of the present invention comprises:
Due to its excellent performance, it is extremely useful as a binder for a coating composition for web offset printing paper.

[0045]

The present invention will now be described more specifically with reference to examples. In the examples, “%” and “parts” are based on weight. <Examples 1 and 2> (Production method of copolymer latex) 0.1 part of seed latex containing carboxy-modified polystyrene having an average particle diameter of 30 nm and 150 parts of water were placed in a 100-liter pressure-resistant container.
After charging 0.3 parts of sodium dodecylbenzenesulfonate and 1.0 part of potassium persulfate, sodium dodecylbenzenesulfonate was added at 0.degree.
Two parts, and the second stage components shown in Table 1, were added continuously for 8 hours. Thereafter, the reaction was continued for another 5 hours to complete the polymerization. The final polymerization addition rate was 98%. The obtained copolymer latex is adjusted to pH 7.5 using sodium hydroxide, and then steam is blown to remove unreacted monomers. A copolymer latex was obtained. The average particle size of the obtained copolymer latex was determined by a conventional method using a particle size measuring device manufactured by Otsuka Electronics Co., Ltd. The toluene-insoluble content of the copolymer latex was determined by the method described above. GPC of copolymer contained in copolymer latex
In the molecular weight distribution obtained from the measurement, the proportion of the component detected faster than the elution time corresponding to 1.1 million in terms of the molecular weight in terms of polystyrene was also determined by the method described above. Table 5 shows the results.

(Preparation of Paper Coating Composition) A paper coating composition for web offset printing was prepared by using the copolymer latex prepared above according to the following formulation. Formulation: Kaolin clay 50.0 parts Calcium carbonate 50.0 parts Dispersant 0.2 part Sodium hydroxide 0.1 part Starch 4.0 parts Latex (as solid content) 10.0 parts Water Total solid content is 60% Add an appropriate amount so that

The composition for paper coating is coated on a base paper for coating with an electric blade coater (manufactured by Kumagaya Riki Kogyo) so that the coating amount is 18.0 ± 0.5 g / m ^2. And 150 ° C
Was dried for 15 seconds with an electric hot air dryer. The coated paper thus obtained was allowed to stand in a thermo-hygrostat at a temperature of 23 ° C. and a humidity of 50% for a day and a night, after which a linear pressure of 100 kg / cm and a roll temperature of 50 were applied.
Supercalendering was performed four times under the condition of ° C. The performance evaluation of the obtained coated paper was performed by the following method. (1) Dry pick strength The degree of picking when printed with an RI printing machine was visually judged and evaluated on a five-point scale. The lower the picking phenomenon, the higher the score. The numerical values are shown as an average value of six measurements. (2) Wet pick strength Using a RI printing machine, the surface of the coated paper was moistened with a water-absorbing roll, and then the degree of picking when printed with the RI printing machine was visually judged and evaluated on a five-point scale. The lower the picking phenomenon, the higher the score. The numerical values are shown as an average value of six measurements. (3) Blister resistance After the double-sided printing coated paper was humidified (about 6%), it was put into a heated oil bath and indicated at the lowest temperature at which blisters were generated. (4) Printing gloss Using a RI printing machine, the ink for offset is solid-coated,
The measurement was performed at an angle of 60 degrees using a Murakami gloss meter. (5) Anti-stickiness Latex was coated on polyethylene terephthalate film with It is applied with an 18 rod and dried at 120 ° C. for 30 seconds to form a film. Combine this film and Kurosa paper and use a bench super calendar to apply a linear pressure of 200 kg /
and pressure bonding under conditions of 70 ° C. The two were peeled off, and the degree of transfer of black kraft paper to latex was visually observed.
Evaluate on a scale. The lower the transfer, the higher the score.
The numerical values are shown as an average value of six measurements. (6) Mechanical stability Copolymer latex (solid content: 30% by weight, sample: 120 g) using a commercially available Malon-type mechanical stability tester
In addition, rotor speed 1000rpm, rotor load 15
After applying mechanical shearing under the conditions of Kg and a rotation time of 15 minutes,
Aggregates remaining on the 120 mesh wire net were captured. After drying the captured agglomerates, the ratio of the agglomerates to the original sample solids weight was determined in weight percent. Table 5 shows the results evaluated by the above evaluation method.

<Examples 3 and 4> In a 100-liter pressure vessel, 150 parts of water, 0.1 part of sodium dodecylbenzenesulfonate, 1.0 part of potassium persulfate, and the first-stage components shown in Table 1 were placed. After charging, in a nitrogen atmosphere at a temperature of 7
Polymerization was carried out at 0 ° C. for 2 hours. Next, the second-stage components shown in Table 1 were continuously added for 8 hours. Thereafter, the reaction was continued for another 5 hours to complete the polymerization. The final polymerization addition rate was 98%. About the obtained copolymer latex, pH adjustment and concentration were performed in the same manner as in Example 1. The average particle diameter of the obtained copolymer latex,
In the toluene insoluble matter and the molecular weight distribution obtained from the GPC measurement, the proportion of the component detected faster than the elution time corresponding to 1.1 million in terms of the molecular weight in terms of polystyrene was determined by the same method as in Example 1. Table 5 shows the results. Preparation of the paper coating composition, preparation of the coated paper, and performance evaluation of the prepared coated paper were performed in the same manner as in Example 1. Table 5 shows the results of the evaluation of the coated paper.

<Examples 5 and 6> In a 100-liter pressure vessel, 150 parts of water, 0.5 part of sodium dodecylbenzenesulfonate, 0.8 part of potassium persulfate, and Table 1,
After charging the first-stage components shown in Table 2, polymerization was carried out at 70 ° C. for 15 hours in a nitrogen atmosphere. The final polymerization addition rate was 98%. About the obtained copolymer latex, pH adjustment and concentration were performed in the same manner as in Example 1.
In the obtained copolymer latex, in the average particle diameter, toluene-insoluble matter, and the molecular weight distribution obtained from the GPC measurement, the ratio of the component detected faster than the elution time corresponding to 1.1 million in terms of the molecular weight in terms of polystyrene was determined as in Example 1. Asked in the same way. The results are shown in Tables 5 and 6. Preparation of the paper coating composition, preparation of the coated paper, and performance evaluation of the prepared coated paper were performed in the same manner as in Example 1. Tables 5 and 6 show the results of the evaluation of the coated paper.

<Examples 7 and 8> In a 100-liter pressure vessel, 150 parts of water, 0.5 part of sodium dodecylbenzenesulfonate, 0.3 part of potassium persulfate, and the first-stage components shown in Table 2 were placed. After charging, in a nitrogen atmosphere at a temperature of 6
Polymerization was carried out at 0 ° C. for 4 hours. Next, the second-stage components shown in Table 1 were charged all at once, and polymerization was further performed for 10 hours. The final polymerization addition rate was 98%. About the obtained copolymer latex, pH adjustment and concentration were performed in the same manner as in Example 2. In the obtained copolymer latex, the average particle diameter, toluene-insoluble matter, and molecular weight distribution obtained from GPC measurement were 1 in terms of polystyrene equivalent molecular weight.
The proportion of components detected faster than the elution time corresponding to 100,000 was determined by the same method as in Examples 1 and 2. Table 6 shows the results.
Shown in Preparation of the paper coating composition, preparation of the coated paper, and performance evaluation of the prepared coated paper were performed in the same manner as in Example 1. Table 6 shows the results of the evaluation of the coated paper.

<Examples 9, 10, 11, and 12> (Preparation of paper coating compositions of Examples 9, 10, 11, and 12) Except that the following copolymer latex and pigment were used, Performed similarly to 1. Pigment (parts) Copolymer latex Calcium carbonate Clay Example 9 Latex of Example 1 60 40 Example 10 Latex of Example 2 60 40 Example 11 Latex of Example 1 20 80 Example 12 Latex of Example 2 20 80 Production of coated paper and performance evaluation of the produced coated paper were performed in the same manner as in Example 1. Tables 6 and 7 show the results of the evaluation of the coated paper.

<Comparative Examples 1 and 2> In a 100-liter pressure vessel, 0.1 part of a seed latex containing carboxy-modified polystyrene having an average particle diameter of 30 nm, 150 parts of water, 0.3 part of sodium dodecylbenzenesulfonate, persulfuric acid After charging 1.0 part of potassium, in a nitrogen atmosphere, at a temperature of 70
℃, sodium dodecylbenzenesulfonate 0.2
And the second stage components shown in Table 3 were continuously added for 8 hours. Thereafter, the reaction was continued for another 5 hours to complete the polymerization. The final polymerization addition rate was 98%. About the obtained copolymer latex, pH adjustment and concentration were performed in the same manner as in Example 1. About the obtained copolymer latex, the average particle diameter, toluene-insoluble matter, and GP
In the molecular weight distribution obtained from the C measurement, the proportion of the component detected faster than the elution time corresponding to 1.1 million in terms of the molecular weight in terms of polystyrene was determined by the same method as in Example 1. Table 7 shows the results. Preparation of the paper coating composition, preparation of the coated paper, and performance evaluation of the prepared coated paper were performed in the same manner as in Example 1. Table 7 shows the results of the evaluation of the coated paper.

Comparative Examples 3 and 4 In a 100-liter pressure vessel, 150 parts of water, 0.1 part of sodium dodecylbenzenesulfonate, 1.0 part of potassium persulfate, and the first-stage components shown in Table 3 were placed. After charging, in a nitrogen atmosphere at a temperature of 7
Polymerization was carried out at 0 ° C. for 2 hours. Next, the second-stage components shown in Table 3 were continuously added for 8 hours. Thereafter, the reaction was continued for another 5 hours to complete the polymerization. The final polymerization addition rate was 98%. About the obtained copolymer latex, pH adjustment and concentration were performed in the same manner as in Example 1. The average particle diameter of the obtained copolymer latex,
In the toluene insoluble matter and the molecular weight distribution obtained from the GPC measurement, the proportion of the component detected faster than the elution time corresponding to 1.1 million in terms of the molecular weight in terms of polystyrene was determined by the same method as in Example 1. The results are shown in Tables 7 and 8. Preparation of the paper coating composition, preparation of the coated paper, and performance evaluation of the prepared coated paper were performed in the same manner as in Example 1. Tables 7 and 8 show the results of the evaluation of the coated paper.

Comparative Examples 5 and 6 150 parts of water, 0.5 parts of sodium dodecylbenzenesulfonate, 0.8 parts of potassium persulfate were placed in a 100-liter pressure-resistant container.
After charging the first-stage components shown in Table 3, polymerization was carried out at 70 ° C. for 15 hours in a nitrogen atmosphere. The final polymerization addition rate was 98%. About the obtained copolymer latex, pH adjustment and concentration were performed in the same manner as in Example 1.
In the obtained copolymer latex, in the average particle diameter, toluene-insoluble matter, and the molecular weight distribution obtained from the GPC measurement, the ratio of the component detected faster than the elution time corresponding to 1.1 million in terms of the molecular weight in terms of polystyrene was determined as in Example 1. Asked in the same way. Table 8 shows the results. Preparation of the paper coating composition, preparation of the coated paper, and performance evaluation of the prepared coated paper were performed in the same manner as in Example 1. Table 8 shows the results of the evaluation of the coated paper.

Comparative Examples 7 and 8 150 parts of water, 0.5 part of sodium dodecylbenzenesulfonate, 0.3 part of potassium persulfate and the first-stage components shown in Table 4 were placed in a 100-liter pressure vessel. After charging, in a nitrogen atmosphere at a temperature of 6
Polymerization was carried out at 0 ° C. for 4 hours. Next, the second-stage components shown in Table 4 were charged all at once, and polymerization was further performed for 10 hours. The final polymerization addition rate was 98%. About the obtained copolymer latex, pH adjustment and concentration were performed in the same manner as in Example 1. In the obtained copolymer latex, the average particle diameter, toluene-insoluble matter, and molecular weight distribution obtained from GPC measurement were 1 in terms of polystyrene equivalent molecular weight.
The proportion of components detected faster than the elution time corresponding to 100,000 was determined by the same method as in Example 1. Table 8 shows the results. Preparation of the paper coating composition, preparation of the coated paper, and performance evaluation of the prepared coated paper were performed in the same manner as in Example 1. Table 8 shows the results of the evaluation of the coated paper.

[0056]

[Table 1]

[0057]

[Table 2]

[0058]

[Table 3]

[0059]

[Table 4]

[0060]

[Table 5]

[0061]

[Table 6]

[0062]

[Table 7]

[0063]

[Table 8]

As is apparent from the results shown in Tables 5 to 8, the copolymer latex of Examples 1 to 12 has achieved the object of the present invention. This is because the copolymer latex has a toluene-insoluble content of 80% by weight or more, has high resistance to extremely large deformation at the time of high-speed printing, exhibits high adhesive strength, and further has high permeability in the coating layer. It is based on the fact that blister resistance is excellent since temper is kept moderately. On the other hand, the copolymer latexes of Comparative Examples 1 to 8 have low toluene-insoluble content and are inferior in their performance, and also have low tackiness and poor printing gloss due to a large amount of low molecular weight components.

[0065]

EFFECT OF THE INVENTION The copolymer latex for paper coating obtained by the present invention and the composition for paper coating using the same have an adhesive strength, a blister resistance, which cannot be achieved by the prior art.
The two properties of stickiness prevention and print gloss contradict each other, and the balance of physical properties can be greatly improved. Furthermore, it has a remarkably improved mechanical stability and excellent characteristics in coating operability, printing operability, and printing suitability, and has extremely high industrial value.

[Brief description of the drawings]

FIG. 1 is an elution curve showing the detection time and elution amount obtained by GPC measurement.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shuji Hara 2--11-24 Tsukiji, Chuo-ku, Tokyo Inside JSR Co., Ltd. (72) Inventor Katsuhiko Tsuruoka 2-11-24 Tsukiji, Chuo-ku, Tokyo JSR In-house F term (reference) 2H113 AA06 BA05 BB08 DA46 DA57 FA10 FA16 FA32 4L055 AG11 AG12 AG27 AG47 AG63 AG70 AG71 AG74 AG76 AG97 AH02 AH37 AJ04 EA30 EA32 EA33 FA12 FA13 FA30 GA19

Claims (5)

[Claims] (1) 10 to 80 parts by weight of a conjugated diene monomer and (b) 0.5 of an ethylenically unsaturated carboxylic acid monomer.
To 15 parts by weight, and 5 to 89.5 parts by weight of (c) another monomer copolymerizable with the (a) conjugated diene monomer and (b) the ethylenically unsaturated carboxylic acid monomer. Here, the total amount of (a), (b) and (c) is 100 parts by weight) and a copolymer obtained by emulsion polymerization in an aqueous medium, and the toluene-insoluble content is 80% by weight or more. A copolymer latex for paper coating, which is characterized in that: 2. In the molecular weight distribution of the copolymer obtained by gel permeation chromatography, the proportion of components detected earlier than the elution time corresponding to 1.1 million in terms of polystyrene equivalent molecular weight is 50% or more. The copolymer latex for paper coating according to claim 1, characterized in that: 3. The copolymer latex for paper coating according to claim 1, which is used for coated paper for web offset printing. 4. 100 parts by weight of a pigment comprising 30 to 100% by weight of calcium carbonate and 0 to 70% by weight of a pigment other than calcium carbonate (the total of both is 100% by weight). Item 6. A paper coating composition comprising the copolymer according to Item 2. 5. The paper coating composition according to claim 4, which is used for coated paper for web offset printing.