JP2002069893A - Copolymer latex for paper-coating and use thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a copolymer latex for a paper coating use having excellent surface strength and an ink build-up property and having low odor, especially the copolymer latex for the coating of white paper board suitable for offset printing and food use. SOLUTION: The copolymer latex is produced by the emulsion polymerization of 100 pts.wt. of a monomer mixture composed of 20-60 wt.% 1,3-butadiene, 1-10 wt.% ethylenic unsaturated carboxylic acid monomer and 30-79 wt.% other monomer copolymerizable with the above monomers. The amount of residual 4-vinylcyclohexene in the copolymer latex is <=30 ppm based on the solid component of 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 copolymer latex for paper coating used in the production of coated paper, and its use. In detail, surface strength, excellent ink inking property, and a low-odor paper coating copolymer latex, and the copolymer latex for offset printing,
The present invention relates to a copolymer latex for coating paper used for coating white paperboard, and a copolymer latex for coating white paperboard used for food applications.

[0002]

2. Description of the Related Art In recent years, coated paper has been used for a very large number of printed materials because of its high printing effect.
Even in quarterly and monthly periodicals, the number of cases where coated paper is used in all sections has increased considerably. In particular, most of direct mail and product catalogs in the mail order business use coated paper for all items. In addition, coated white paperboard is mainly used for packaging materials, especially for interiors and individual packaging, but a good printing effect is required. In recent years, coated white paperboard is often used for food applications. However, when odor is generated from the coated white paperboard, the commercial value is significantly reduced, which is a serious problem.

[0003] Coated paper and coated white paperboard are produced by coating a paper coating composition on the surface of a coated base paper and drying. Generally, a paper coating composition is a water-based paint composed of a pigment dispersion in which a white pigment such as clay or calcium carbonate is dispersed in water, a binder for bonding and fixing the pigments or the pigment to the base paper, and other additives. is there. As the binder, a synthetic emulsion binder typified by a butadiene copolymer latex and a natural binder typified by starch and casein are used. Among them, butadiene copolymer latex has a large degree of freedom in quality design, and is widely used today as the most suitable binder for paper coating compositions. It is said that it greatly affects the performance, the operability during the production of coated paper, and the quality of the final coated paper product such as odor.

[0004] In particular, today, when offset printing is further accelerated, a higher level of surface strength is required for coated paper than ever before. In offset printing, fountain solution is supplied to the non-image areas of the printing plate to which the printing ink should not originally adhere to prevent ink from adhering to the non-image areas. Although the phenomenon of soiling is called "ground stain", background printing is becoming more likely to occur due to the speeding up of printing.To prevent this, dampening water supplied to non-image areas when printing is used. Tend to increase from the past. However, as a result, a part of the dampening solution is absorbed on the surface of the coated paper, which is a printing medium, causing poor ink reception, or the dampening solution is not applied to the coated paper from a printing press blanket. When applied evenly, ink reception unevenness occurs, so that the printing effect is remarkably reduced in many cases. In particular, in recent years, there has been a strong demand for improvement in this respect, and technical attention has been focused on improving the ink inking property of coated paper after being wetted with water. From these viewpoints, various quality improvement techniques have been introduced for quality design and production methods of butadiene-based copolymer latex used as a binder for paper coating compositions. For example. By polymerizing in the presence of a hydrocarbon having one unsaturated bond in the ring, it is possible to reduce fine coagulation during polymerization, and to improve the mechanical stability, adhesiveness, and A technique for improving odor is introduced in Japanese Patent Application Laid-Open No. 5-279406. For coated white paperboard, Japanese Patent Application Laid-Open No. 6-65898 discloses offset / gravure printing suitability for offset / gravure printing shared white paperboard, and styrene in a coating composition as coated white paperboard used for food applications. JP-A-10-33109 describes the use of acrylic latex.
No. 6, there is no description about the odor of the coated paper. Furthermore, JP-A-11-60817 discloses a copolymer latex for a paperboard coating composition, but also does not describe the odor of the coated paper in the present invention. In particular, in the case of coated white paperboard used for food applications, if odor is generated, not only is the commercial value significantly reduced, but also safety and health problems arise.

[0005] However, these various improvements alone have not yet reached the level of sufficiently satisfying the required performance, and further improvements have been demanded. In particular, the effect of improving the balance between the surface strength and the ink inking property is not sufficient, and the improvement has been strongly demanded. In addition, a drastic solution has not yet been proposed for the study to reduce the odor generated from the coated paper.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a copolymer latex for paper coating which is excellent in surface strength and ink inking property and has a low odor, and the copolymer latex for offset printing, An object of the present invention is to provide a copolymer latex for coating paperboard used for coating white paperboard, and a copolymer latex for coating coated white paperboard used for food applications.

[0007]

Means for Solving the Problems In view of the above-mentioned circumstances, the present inventors have made intensive studies to solve the present problems, and as a result, have found that the reaction formation of 1,3-butadiene by-produced in the polymerization process. By limiting the amount of 4-vinylcyclohexene, which is a product, to a specific amount or less, a paper coating copolymer having low odor in coated white paperboard used in products, particularly for food applications, and having excellent physical properties in various applications. It has been found that latex can be obtained, and the present invention has been completed.

That is, the present invention relates to 1,3-butadiene 2
0 to 60% by weight, ethylenically unsaturated carboxylic acid monomer 1
To 10% by weight and other monomers copolymerizable therewith 3
A copolymer latex obtained by emulsion-polymerizing a total of 100 parts by weight of a monomer composed of 0 to 79% by weight, wherein 4-vinylcyclohexene remaining in the copolymer latex is replaced with the copolymer latex. 30ppm based on solid content of
The present invention provides a copolymer latex for paper coating characterized by the following.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.

As the ethylenically unsaturated carboxylic acid monomer constituting the copolymer latex in the present invention, mono- or dicarboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid and itaconic acid (anhydrous ), And one or more of these can be used.

Other monomers copolymerizable with 1,3-butadiene and the ethylenically unsaturated carboxylic acid monomer include alkenyl aromatic monomers, unsaturated carboxylic acid alkyl ester monomers, and hydroxyalkyl Examples include an unsaturated monomer containing a group, a vinyl cyanide monomer, and an unsaturated carboxylic acid amide monomer.

The alkenyl aromatic monomer includes styrene, α-methylstyrene, methyl α-methylstyrene,
Vinyl toluene and divinyl benzene, and the like,
One or more of these can be used. Particularly, the use of styrene is preferred.

Examples of unsaturated carboxylic acid alkyl ester monomers include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, glycidyl methacrylate, dimethyl fumarate, diethyl fumarate, dimethyl maleate, diethyl maleate, dimethyl dimethyl Examples thereof include itaconate, monomethyl fumarate, monoethyl fumarate, and 2-ethylhexyl acrylate, and one or more of these can be used. Particularly, use of methyl methacrylate is preferred.

Examples of unsaturated monomers containing a hydroxyalkyl group include β-hydroxyethyl acrylate and β-hydroxyethyl acrylate.
-Hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate,
Hydroxybutyl acrylate, hydroxybutyl methacrylate, 3-chloro-2-hydroxypropyl methacrylate, di- (ethylene glycol) maleate,
Di- (ethylene glycol) itaconate, 2-hydroxyethyl maleate, bis (2-hydroxyethyl)
Maleate, 2-hydroxyethyl methyl fumarate and the like can be mentioned, and one or more of these can be used. Particularly, use of β-hydroxyethyl acrylate is preferred.

Examples of the vinyl cyanide monomer include acrylonitrile, methacrylonitrile, α-chloroacrylonitrile, α-ethylacrylonitrile and the like.
One or more of these can be used. In particular, use of acrylonitrile or methacrylonitrile is preferred.

The unsaturated carboxylic acid amide monomers include:
Acrylamide, methacrylamide, N-methylol acrylamide, N-methylol methacrylamide, N,
N-dimethylacrylamide and the like can be mentioned, and one or more of these can be used. Particularly, use of acrylamide or methacrylamide is preferred.

The above monomer composition is composed of 20 to 60% by weight of 1,3-butadiene, 1 to 10% by weight of an ethylenically unsaturated carboxylic acid monomer, and 30% of another monomer copolymerizable therewith.
~ 79% by weight.

When 1,3-butadiene is less than 20% by weight, the dry pick strength of the surface strength required for printing is more than 60% by weight. Poor pick strength,
It is not preferable because the odor is inferior. Preferably it is 25 to 55% by weight.

If the amount of the ethylenically unsaturated carboxylic acid monomer is less than 1% by weight, the mechanical stability of the copolymer latex itself and the paper coating composition may be poor, and more than 10% by weight. And the viscosity of the latex becomes high, which may cause a problem in handling the copolymer latex itself, which is not preferable. Preferably it is 1 to 7% by weight.

When the amount of the other copolymerizable monomer is less than 30% by weight, the wet pick strength is poor, and when it is more than 79% by weight, the dry pick strength is inferior. More preferably, it is 38 to 74% by weight.

It is necessary that the amount of 4-vinylcyclohexene remaining in the copolymer latex of the present invention is not more than 30 ppm based on the solid content of the latex. If the residual amount of 4-vinylcyclohexene exceeds 30 ppm, the wet pick strength is poor and the odor is poor. Preferably it is 10 ppm or less. The method for reducing the amount of residual 4-vinylcyclohexene can be appropriately adjusted according to the monomer composition of the copolymer latex and the method for adding the same, the polymerization temperature, and the aging temperature and the aging time after the polymerization. . Furthermore, it can be appropriately adjusted by the conditions of steam distillation after polymerization and the conditions of decompression treatment for heating.

Although the gel content of the copolymer latex of the present invention is not particularly limited, a preferable gel content is from 40 to 100, particularly from the viewpoint of dry pick strength among surface strengths required for offset printing. % By weight.

The particle size of the copolymer latex is not particularly limited, but the preferred particle size of the copolymer latex is 0.2 μm or less. More preferably,
It is 0.18 μm or less, and the most preferred particle size of the copolymer latex is 0.05 to 0.15 μm.

The chain transfer agent which can be used in the present invention includes α-methylstyrene dimer, n-hexyl mercaptan, n-octyl mercaptan, t-
Octyl mercaptan, n-dodecyl mercaptan, t
-Thiuram compounds such as alkyl mercaptans such as dodecyl mercaptan and n-stearyl mercaptan, xanthogen compounds such as dimethyl xanthogen disulfide and diisopropyl xanthogen disulfide, terpinolene, tetramethylthiuram disulfide, tetraethylthiuram disulfide and tetramethylthiuram monosulfide; Phenolic compounds such as 2,6-di-t-butyl-4-methylphenol and styrenated phenol; allyl compounds such as allyl alcohol; halogenated hydrocarbon compounds such as dichloromethane, dibromomethane and carbon tetrabromide; α-benzyl Oxystyrene, α-benzyloxyacrylonitrile, vinyl ethers such as α-benzyloxyacrylamide, triphenylethane, pentaphenylethane, Kurorein, methacrolein,
Thioglycolic acid, thiomalic acid, 2-ethylhexyl thioglycolate and the like.
More than one species can be used. Although the amount of the chain transfer agent is not particularly limited, it is generally used in an amount of 0 to 5 parts by weight based on 100 parts by weight of the monomer.

The polymerization method in the present invention may employ any one of a one-stage polymerization, a two-stage polymerization, a multi-stage polymerization, a seed polymerization and a power feed polymerization method. The method for adding the various components in the polymerization method of the present invention is not particularly limited, and any of a batch addition method, a division addition method, and a continuous addition method can be employed. Further, in the emulsion polymerization, a commonly used emulsifier, a polymerization initiator, a hydrocarbon compound,
An electrolyte, a polymerization accelerator, a chelating agent and the like can be used.

The emulsion polymerization of the present invention is carried out using water as a medium in the presence of an emulsifier. As the emulsifier used in the emulsion polymerization of the present invention, one or more of anionic surfactants, nonionic surfactants, amphoteric surfactants, and even cationic surfactants are used alone or in combination. can do. Examples of anionic surfactants include higher alcohol sulfates (sodium lauryl sulfate, sodium dodecyl sulfate), alkylbenzene sulfonates (sodium dodecylbenzene sulfonate, potassium dodecylbenzene sulfonate, ammonium dodecylbenzene sulfonate), alkyl Diphenyl ether sulfonates (sodium dodecyl diphenyl ether sulfonate, sodium dodecyl diphenyl ether disulfonate, disodium palmityl diphenyl oxide disulfonate), aliphatic sulfonates (sodium α-olefin (C11-C15) sulfonate, sodium lauryl sulfonate) , Ethoxylated sulfate (sodium alkylphenol ethoxylate sulfate), ester of sulfosuccinic acid (dihexylsulfokohama) Sodium acid, hexyl sodium sulfosuccinate dicyclohexyl, sodium diamyl sulfosuccinate, sodium diisobutyl sulfosuccinate, sulfosuccinic acid disodium ethoxylated nonylphenol half ester tetrasodium N, (1,2-di-carboxyethyl) -
N-octadecyl sulfosuccinate, disodium isodecyl sulfosuccinate, sodium bistridecyl sulfosuccinate), sodium salt of condensed naphthalene sulfonate, alkyl allyl sulfonate (sodium salt of alkyl allyl polyether sulfate), aliphatic carboxylic acid Acid salt (sodium or potassium salt of lauric acid, stearic acid, montanic acid, behenic acid, palmitic acid), sulfate salt of nonionic surfactant (polyoxyethylene lauryl ether sodium sulfate, sodium polyoxyethylene cetyl ether sulfate) , Polyoxyalkylene alkyl ether sulfates such as sodium polyoxyethylene stearyl ether sulfate and sodium polyoxyethylene oleyl ether sulfate; polyoxyethylene nonyl sulfate Polyoxyalkylene aryl ether sulfates such as sodium phenyl ether sulfate and sodium polyoxyethylene octyl phenyl ether sulfate; polyoxyethylene (7) [distyrenated (methylphenyl ether)] ammonium sulfate; and polyoxypropylene (8) [ Distyrenated (methylphenyl ether)] sulfate ammonium salt,
Polyoxyethylene (30) [distyrenated (methylphenyl ether)] sulfate ammonium salt, polyoxyethylene (12) [distyrenated (butylphenyl ether)] sulfate sodium salt, polyoxyethylene (10) [methyldistyrene (Methyl phenyl ether)] sulfate sodium salt, polyoxypropylene (20) [methyldistyrenated (methyl phenyl ether)] sulfate sodium salt, [polyoxypropylene (5) polyoxyethylene (6)] random [ Distyrenated (methylphenyl ether)] sulfate ammonium salt, [polyoxypropylene (1
0) polyoxyethylene (20)] block [distyrenated methyl phenyl ether)] sulfate sodium salt) and the like. Examples of nonionic surfactants include polyethylene glycol alkyl ester type, alkyl phenyl ether type, and alkyl ether type (polyethylene glycol monostearate, polyoxyethylene sorbitan lauryl ester, polyoxyethylene nonylphenyl ether, polyoxyethylene octyl). Phenyl ether, polyoxyethylene lauryl ether, polyoxyethylene stearyl ether) and the like. Further, examples of the amphoteric surfactant include those of an amino acid type such as salts of alkyl betaines such as lauryl betaine and stearyl betaine, and salts of lauryl-β-alanine, lauryl di (aminoethyl) glycine, and octyl di (aminoethyl) glycine. And the like.

As the polymerization initiator, a water-soluble polymerization initiator such as potassium persulfate, sodium persulfate and ammonium persulfate, a redox-based polymerization initiator, and an oil-soluble polymerization initiator such as benzoyl peroxide can be appropriately used. In particular, it is preferable to use a water-soluble polymerization initiator of potassium persulfate or sodium persulfate.

In the polymerization, saturated hydrocarbons such as pentane, hexane, heptane, octane, cyclohexane and cycloheptane, pentane, hexene, heptene, cyclopentene, cyclohexene, cycloheptene, 4-methylcyclohexene, 1-methylcyclohexene and the like can be used. Hydrocarbon compounds such as saturated hydrocarbons and aromatic hydrocarbons such as benzene, toluene and xylene may be used. In particular, the components having a moderately low boiling point and remaining as unreacted substances after the polymerization are recovered by steam distillation or the like,
Cyclohexene, which is easy to recycle, is preferred.

The copolymer latex produced in the present invention is used together with a pigment as a binder constituting a paper coating composition. Examples of such pigments include kaolin clay, talc, barium sulfate, titanium oxide, calcium carbonate, aluminum hydroxide, zinc oxide,
Examples thereof include inorganic pigments such as satin white and organic pigments such as polystyrene latex, and these are used alone or in combination.

If necessary, a modified starch such as starch, oxidized starch and esterified starch, a natural binder such as soybean protein and casein, or a water-soluble synthetic binder such as polyvinyl alcohol may be used. Further, synthetic latex such as polyvinyl acetate latex and acrylic latex may be used in combination with the copolymer latex of the present invention. It is desirable to suppress the solid content of the polymer latex to less than 50% by weight.
Further, it is desirable to keep the content to less than 20% by weight, and it is most desirable to use the copolymer latex of the present invention alone.

When preparing a paper coating composition using the copolymer latex of the present invention, other auxiliary agents such as dispersants (sodium pyrophosphate, sodium polyacrylate, sodium hexametaphosphate, etc.) Foaming agent (polyglycol, fatty acid ester, phosphate ester,
Requires silicone oil), leveling agent (funnel oil, dicyandiamide, urea, etc.), preservative, release agent (calcium stearate, paraffin emulsion, etc.), fluorescent dye, color water retention improver (carboxymethyl cellulose, sodium alginate, etc.) May be added according to the requirements.

Further, the method for applying the paper coating composition to the base paper for coating may be performed by a known technique, for example, using any coating machine such as an air knife coater, a blade coater, a roll coater, and a bar coater. No problem. After coating, the surface is dried and finished with a calender ring or the like.

The copolymer latex for paper coating in the present invention can be used especially for offset printing.
A coated paper for offset printing having low surface strength, ink adhesion and odor can be obtained, and the present invention is further improved by using the copolymer latex for coated white paperboard, especially for food use. The effect of can be exhibited.

[0034]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples unless it exceeds the gist. In the examples, parts and% indicating percentages are based on weight unless otherwise specified. The methods for preparing the copolymer latex and the evaluation of various physical properties in the examples were based on the following methods.

[0035]Steam distillation  Copolymerized latte with polymerization completed in a pressure resistant container having an internal volume of 100 L
40 kg, and an appropriate amount of defoamer
Adjust the latex PH to 7 with soda and add it to Tables 1 and 2.
Heated to the indicated temperature. Then, from the bottom of the pressure vessel
Steam is supplied at a constant rate, and the distillate is
To perform steam distillation at a predetermined temperature.
Was. The amount of steam supplied and the amount of distillate were
It was almost the same.

[0036]Evaluation of dry pick strength of coated paper  Tack value with relatively high splitting resistance using RI printing machine
Simultaneously prints each coated paper sample with 18 inks,
The degree of picking is judged with the naked eye, and class 5 (best)
To 1st grade (worst). 6 signs
A printing test was performed and the average was determined.

[0037]Evaluation of wet pick strength of coated paper  Each coated paper sample by Molton roll using RI printing machine
To the dampening solution at the same time,
Is the same for each coated paper sample with an ink with a medium tack value of 12.
Sometimes printed, and the degree of picking at that time is judged with the naked eye
And relative from grade 5 (best) to grade 1 (worst)
Was evaluated. Six printing tests were performed and the average value was determined.

[0038]Ink deposition  Simultaneously dampening solution for each coated paper sample using RI printing machine
Immediately after that, a process for black offset printing is performed.
Mark when the ink was simultaneously printed on each coated paper sample
The printing density is judged with the naked eye, and it is determined that the printing density is 5 (darkest) to 1
Relatively thin). 6 printing tests
The average was determined.

[0039]4-vinyl residue in the copolymer latex
Clohexene measurement  4-vinylcyclohexene in the copolymer latex is
Using a gas chromatograph GC-14A manufactured by Shimadzu Corporation
The following method was used. (1) Preparation of sample 4 g of copolymer latex (solid content: 45 to 50% by weight)
Was weighed accurately and dissolved in 40 ml of dimethylformamide.
After immersion in a closed container for 30 minutes, a sample was prepared. (2) Gas chromatograph measurement conditions Sample amount: 3 μl Detector: FID Inj / Det temperature: 200 ° C. Column temperature: 105 ° C. × 40 min Column: glass column 4 m × 3 mmφ Stationary phase: PEG-20M Celite 545 60/80 MESH Carrier gas: N2, 40 ml / min. Hydrogen: 0.5 kg / cm2 Air: 0.7 kg / cm2 Quantitative method Prepared using known concentration of 4-vinylcyclohexene
Using the calibration curve, obtain the weight from the obtained gas chromatograph.
4-vinylcyclohexene for coalesced latex solids
The quantitative value of Sun was determined. Measure three times for the same sample,
The average value was shown in ppm.

[0040]Measurement of particle size of copolymer latex  The number average particle diameter was measured by a dynamic light scattering method. When measuring
Use LPA-3000 / 3100 made by Otsuka Electronics
did.

[0041]Measurement of gel content of copolymer latex  A latex film is prepared at room temperature. afterwards
About 1 g of a latex film is weighed and 400 cc
And swell and dissolve for 48 hours in toluene. afterwards,
This is filtered through a 300 mesh wire mesh and captured by the wire mesh.
The dried toluene insolubles were weighed after drying, and the first latex
The ratio of the weight to the weight of the film is defined as the gel content.
And calculated in% by weight.

[0042]Odor evaluation  10 g of each coated paper sample cut into 3 cm square, 500 ml of odor
After placing in an air bottle and leaving at 20 ° C for 24 hours,
After heating for 0 minutes and cooling, smell the odor of the sample.
Depending on the degree, it is grade 5 (the odor is low and good) to grade 1 (the odor is
Relatively bad). For each coated paper sample
And average the judgment results of 10 testers to obtain a test result.
Was.

[0043]Production of copolymer latex 1-5, 8-12
Made  In a pressure-resistant polymerization reactor, 120 parts of polymerization water, sodium bicarbonate
0.2 parts of potassium, 1 part of potassium persulfate, and Tables 1 and 2
As shown in the table, the monomer mixture of the number of parts on the left side of "/"
Materials, emulsifiers, chain transfer agents, auxiliaries, etc.
After stirring, polymerization was performed at 70 ° C. for 1 hour. Then Table 1,
In the table shown in Fig. 2, monomer mixture of the number of copies on the right side of "/"
, Emulsifier, chain transfer agent, auxiliaries, etc. continuously over 7 hours
Added. When the polymerization conversion becomes 96% or more, sulfuric acid
Add 0.1 part of droxylamine and caustic soda.
And stop the reaction and adjust the pH to 7.0
did. Next, these copolymer latexes are subjected to steam evaporation.
Distillates (copolymer latexes 1, 3, 5 and 9 at a temperature of 90
° C, the copolymer latexes 2, 4, 8 and 10 have a temperature of 8
0 ° C., the copolymer latex 11-12 has a temperature of 70 ° C.)
After concentration, the solid content was adjusted to 50%, and the results are shown in Tables 1 and 2.
Particle size, gel content, residual 4-vinylcyclohexene amount
To obtain copolymer latex 1 to 5 and 8 to 12
Was.

[0044]Preparation of copolymer latex 6,7  Table 1 (left) shows the pressure-resistant polymerization reactor with nitrogen substitution.
Of polymerization water and emulsifier, and the temperature was raised to 65 ° C.
1.5 parts of potassium acid was added and dissolved.
The mixture of the monomers and other compounds of
After polymerizing for 1 minute, the mixture consisting of the rest shown in Table 1 (right)
The mixture was added over 10 hours, and then heated to 70 ° C.
When the polymerization conversion rate reaches 96% or more, the polymerization terminator
0.1 parts of hydroxylamine sulfate and sodium hydroxide
To terminate the reaction and reduce the latex PH to about
It was adjusted to 7.0. Then, these copolymer latex
Is subjected to steam distillation (copolymer latex 6 is 80 ° C.,
After the combined latex 7 is 90 ° C), it is concentrated to 50% solids.
Was adjusted. Particle size, gel content, residual shown in Tables 1 and 2
Copolymer latex showing 4-vinylcyclohexene content
6,7 were obtained.

[0045]Preparation and evaluation of paper coating composition  According to the following formulation, copolymer latex 1
~ 12 each using different types of copolymer latex
Twelve types of paper coating compositions were prepared.

(Formulation of paper coating composition) Kaolin clay 65 parts Heavy calcium carbonate 25 parts Precipitable calcium carbonate 10 parts Modified starch 3 parts Copolymer latex 9 parts Solid content concentration 65%

[0047]Preparation and evaluation of coated paper  Using a commercially available hot air coating dryer MLC-100S type,
82 g / m²Coated base paper, each obtained paper coating
The composition was coated to produce 12 types of coated paper. What
In addition, each coated paper was produced under the same conditions shown below. Coating conditions: Absorption of the above composition with hot air coating dryer
Dry coating amount is 15g / m on one side²Wire bar
Coating was carried out using The coating speed was 46 m / min. Set in
Specified. Drying condition: about 0.5 seconds after coating, drying oven at 150 ° C
Within 5 seconds with hot air at a temperature of 210 ° C and a wind speed of 33m / s
While drying. Each coated paper obtained was subjected to a relative humidity of 65% and a temperature of 65%.
After adjusting the humidity for 24 hours at a temperature of 20 ° C, a linear pressure of 80 kg /
cm, temperature 60 ° C, paper passing speed 7m / min.
Super calendering and copolymerization under a total of 4 paper passing conditions
Twelve types of coated papers having different body latex were obtained. Obtained
The coated paper was subjected to each test and evaluated.
Latex particle size, gel content, residual 4-vinyl cycle
The results are shown in Tables 1 and 2 together with the amount of rohexene.

[0048]

[Table 1]

[0049]

[Table 2]

[0050]

The copolymer latex for paper coating of the present invention is a copolymer latex having an extremely excellent balance of surface strength, ink adhesion, and odor.
It is extremely useful as a copolymer latex used as a binder for coated white paperboard, and more particularly as a binder for coating coated white paperboard used in food applications.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4J011 KA04 KB29 4J100 AB02P AB03P AB04P AB16P AJ01R AJ02R AJ08R AJ09R AK31R AK32R AL03P AL04P AL08P AL09P AL10P AL34P AL36P AL39P AL46P AS02Q BA02P AG03 AG05 AG02 AG74 AG76 AG89 AH02 AH37 AJ04 BE07 BE08 EA32 FA11 FA13 FA15 GA05 GA19 GA30

Claims (5)

[Claims] 1. A simple composition comprising 20 to 60% by weight of 1,3-butadiene, 1 to 10% by weight of an ethylenically unsaturated carboxylic acid monomer and 30 to 79% by weight of another monomer copolymerizable therewith. A copolymer latex obtained by emulsion polymerization of 100 parts by weight of a total of monomers, wherein 4-vinylcyclohexene remaining in the copolymer latex is 30 ppm or less based on the solid content of the copolymer latex. A copolymer latex for paper coating, characterized in that: 2. The method according to claim 1, wherein 4-vinylcyclohexene remaining in the copolymer latex is not more than 10 ppm based on the solid content of the copolymer latex.
The copolymer latex for paper coating according to the above. 3. The paper latex according to claim 1, which is used for offset printing. 4. The method according to claim 1, which is used for coated white paperboard.
The copolymer latex for paper coating according to the above. 5. The copolymer latex for coating coated white paperboard according to claim 4, which is used for food applications.