JP3502791B2 - Copolymer latex for coating offset printing paper and composition for coating offset printing paper containing the latex - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a copolymer latex used in the production of coated paper for offset printing, and a paper coating composition using the copolymer latex. More particularly, it relates to a copolymer latex for coating offset printing paper, which is excellent in surface strength, printing gloss, and ink receptivity, and a composition for coating offset printing paper using the copolymer latex.

[0002]

2. Description of the Related Art In recent years, coated paper has been used for a very large number of printed matters because of its high printing effect.
Even in periodical publications such as quarterly and monthly papers, the number of cases in which coated paper is used for all items is considerably increasing. In particular, in direct mails and product catalogs in the mail order business, most of them use coated paper for all items.

Coated paper is produced by coating the surface of coated base paper with a paper coating composition 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 adhering and fixing pigments or pigments to a 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 or casein are used. Among them, the butadiene-based copolymer latex has a large degree of freedom in quality design and is widely used today as a binder most suitable for a paper coating composition. It is said to have a great influence on the performance or quality of the final coated paper product such as surface strength, printing gloss and ink receptivity.

Particularly in today's high-speed offset printing, coated papers are required to have a higher surface strength than ever before. Also, in offset printing, dampening water is supplied to the non-printing area of the plate where the printing ink should not originally adhere to prevent ink from adhering to the non-printing area. The phenomenon of stains is called "background stain", but due to the increased printing speed, background stains are more likely to occur. To prevent this, dampening water supplied to the non-image area during printing is used. Tend to increase than before. However, as a result, part of the dampening water is absorbed on the surface of the coated paper, which is the material to be printed, causing poor ink reception, and there is no dampening water on the coated paper from the blanket of the printing press. When applied evenly, unevenness in ink reception occurs, and the number of cases in which the printing effect is remarkably reduced is increasing. Particularly in recent years, there has been a strong demand for improvement in this respect, and the ink receptivity of coated paper after being moistened with water (hereinafter,
Technical attention has been focused on improving the physical properties of the swimsuit.

From these viewpoints, various improved techniques have been heretofore introduced in relation to the quality design and production method of the butadiene copolymer latex used as a binder for a paper coating composition, and some of them have been introduced. Is exemplified below.

JP-A-3-109450 and JP-A 3-1
No. 09451 and JP-A-3-109470 disclose that polymerization is performed in the presence of α-methylstyrene dimer to reduce fine coagulation during polymerization, mechanical stability of copolymer latex, and high-speed coating. Techniques for improving suitability and adhesiveness are introduced. In addition, Japanese Patent Laid-Open No. 3-11309
No. 6 discloses that a paper coating composition having excellent adhesive strength and blister resistance can be obtained by using a copolymer latex polymerized in the presence of α-methylstyrene dimer and another chain transfer agent. There is.

Further, in JP-A-3-8896, polymerization is carried out in the presence of a disulfide compound to reduce fine coagulation during the polymerization and to improve mechanical stability and adhesiveness of the copolymer latex. The technology to do is introduced.

However, these various improved techniques have not yet reached the level at which the required performance is sufficiently satisfied, and further improvements have been required. In particular, the effect of improving the balance between surface strength and the physical properties of the swimsuit is not sufficient,
The improvement was strongly demanded.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to provide a copolymer latex for coating offset printing paper, which is excellent in surface strength, printing gloss and ink receptivity, and offset printing containing the copolymer latex. An object is to provide a composition for coating a paper.

[0010]

Means for Solving the Problems The inventors of the present invention have made diligent studies to solve the current problems in view of the above-mentioned circumstances, and as a result, used a specific copolymer latex and the copolymer latex. The inventors have found that the above-mentioned problems can be solved with a paper coating composition and completed the present invention. That is, the present invention comprises 28 to 60% by weight of an aliphatic conjugated diene monomer and 1 to 10% by weight of an ethylenically unsaturated carboxylic acid monomer.
And 100 parts by weight of a total of 30 to 71% by weight of another monomer copolymerizable therewith by emulsion polymerization in the presence of 0.8 to 2.5 parts by weight of α-methylstyrene dimer. In the obtained copolymer latex, the α-methylstyrene dimer remaining in the copolymer latex is 800 to 2 relative to the solid content of the copolymer latex.
The present invention provides a copolymer latex for coating offset printing paper, which is characterized in that it is 500 ppm, and a composition for coating fuset printing paper containing the copolymer latex.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is described in detail below. Examples of the aliphatic conjugated diene-based monomer in the present invention include 1,3-butadiene, 2-methyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene and 2-chloro-1,3-. Examples thereof include butadiene, substituted linear conjugated pentadienes, substituted and side chain conjugated hexadienes, and these may be used alone or in combination of two or more. The use of 1,3-butadiene is particularly preferable.

Examples of the ethylenically unsaturated carboxylic acid monomer include mono- or dicarboxylic acids (anhydrides) such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid and itaconic acid. Alternatively, two or more kinds can be used.

Other monomers copolymerizable with the above-mentioned aliphatic conjugated diene type monomer and ethylenically unsaturated carboxylic acid monomer include alkenyl aromatic monomer and unsaturated carboxylic acid alkyl ester monomer. And unsaturated monomers containing a hydroxyalkyl group, vinyl cyanide monomers, unsaturated carboxylic acid amide monomers and the like.

As the alkenyl aromatic monomer, styrene, α-methylstyrene, methyl α-methylstyrene,
Vinyltoluene and divinylbenzene and the like,
These may be used alone or in combination of two or more. The use of styrene is particularly preferred.

Examples of the unsaturated carboxylic acid alkyl ester monomer include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, glycidyl methacrylate, dimethyl fumarate, diethyl fumarate, dimethyl maleate, diethyl malate and dimethyl. Itaconate, monomethyl fumarate, monoethyl fumarate, 2-ethylhexyl acrylate and the like can be mentioned, and one or more of these can be used. The use of methyl methacrylate is particularly preferable.

The unsaturated monomer containing a hydroxyalkyl group includes 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)
Examples thereof include maleate and 2-hydroxyethylmethyl fumarate, and these may be used alone or in combination of two or more. It is particularly preferable to use β-hydroxyethyl acrylate.

Examples of vinyl cyanide monomers include acrylonitrile, methacrylonitrile, α-chloroacrylonitrile and α-ethylacrylonitrile.
These may be used alone or in combination of two or more. It is particularly preferable to use acrylonitrile or methacrylonitrile.

As the unsaturated carboxylic acid amide monomer,
Acrylamide, methacrylamide, N-methylol acrylamide, N-methylol methacrylamide, N,
Examples thereof include N-dimethylacrylamide, and these may be used alone or in combination of two or more. The use of acrylamide or methacrylamide is particularly preferred.

The above monomer composition is composed of 28 to 60% by weight of the aliphatic conjugated diene monomer, 1 to 10% by weight of the ethylenically unsaturated carboxylic acid monomer, and another monomer copolymerizable therewith. It consists of 30 to 71% by weight.

When the amount of the aliphatic conjugated diene monomer is less than 28% by weight, the dry pick strength is one of the surface strengths required for printing, and when it exceeds 60% by weight, the surface strength when wet is required for printing. The so-called wet pick strength is inferior, which is not preferable. More preferably, it is 30 to 55% by weight.

When 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 when it exceeds 10% by weight, the latex content may be low. It is not preferable because the viscosity becomes high, which may cause a problem in handling the copolymer latex itself. More preferably, it is 1 to 7% by weight.

If the amount of the other copolymerizable monomer is less than 30% by weight, the wet pick strength will be poor, and if it exceeds 71% by weight, the dry pick strength will be poor, such being undesirable. More preferably, it is 38 to 69% by weight.

The α-methylstyrene dimer used in the present invention includes 2,4-diphenyl-4-methyl-1-pentene, 2,4-diphenyl-4-methyl-2-pentene and 1,2 as isomers. Although there is 1,3-trimethyl-3-phenylindane, the α-methylstyrene dimer used in the present invention is 2,4-diphenyl-
The content of 4-methyl-1-pentene is 60% by weight or more,
It is particularly preferably 80% by weight or more.

The amount of α-methylstyrene dimer present in the polymerization is 0.8 with respect to 100 parts by weight of all the monomers used.
.About.2.5 parts by weight, and even if the amount is less than 0.8 parts by weight or exceeds 2.5 parts by weight, the surface strength or print gloss of either dry pick strength or wet pick strength is increased. descend. Further, the amount of α-methylstyrene dimer remaining in the copolymer latex of the present invention needs to be 800 to 2500 ppm with respect to the solid content of the latex. Preferably 900-2500 pp
m, and more preferably 1000 to 2000 ppm
Is. The residual amount of α-methylstyrene dimer is 250.
If it exceeds 0 ppm, the effect of improving the meat property of the swimsuit which is the main object of the present invention, which is required in high-speed offset printing, cannot be obtained. In addition, the residual amount of α-methylstyrene dimer is 80
If it is less than 0 ppm, the surface strength is lowered. The residual α
-For methylstyrene dimer, the amount used during the polymerization of the copolymer latex and its addition method, the monomer composition of the copolymer latex and its addition method, the polymerization temperature, and the aging temperature and aging time after the polymerization, etc. Can be adjusted as appropriate.

Further, in the present invention, the following chain transfer agent can be used together with α-methylstyrene dimer. Examples of the chain transfer agent include alkyl mercaptans such as n-hexyl mercaptan, n-octyl mercaptan, t-octyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, and n-stearyl mercaptan, dimethylxanthogen disulfide, diisopropylxanthogendiene. Xanthogen compounds such as sulfide, terpinolene, thiuram-based compounds such as tetramethylthiuram disulfide, tetraethylthiuram disulfide and tetramethylthiuram monosulfide, phenols such as 2,6-di-t-butyl-4-methylphenol and styrenated phenol Compounds,
Allyl compounds such as allyl alcohol, dichloromethane,
Dibromomethane, halogenated hydrocarbon compounds such as carbon tetrabromide, α-benzyloxystyrene, α-benzyloxyacrylonitrile, vinyl ethers such as α-benzyloxyacrylamide, triphenylethane, pentaphenylethane, acrolein, methacrolein, thio. Glycolic acid, thiomalic acid, 2-ethylhexyl thioglycolate and the like can be mentioned, and one or more of these can be used. The amount of these chain transfer agents is not particularly limited, but is usually 0 to 5 parts by weight with respect to 100 parts by weight of the monomer.

The polymerization method in the present invention may be any one-step polymerization, two-step polymerization, multi-step polymerization, seed polymerization, power feed polymerization method, etc., but two-step polymerization and multi-step polymerization are particularly preferable. Also, the method of adding various components in the polymerization method of the present invention is not particularly limited, and any of a batch addition method, a divided addition method and a continuous addition method can be adopted. Furthermore, a multi-step polymerization method by a continuous addition method as shown in Examples described later seems to be particularly preferable. Further, in the emulsion polymerization, a commonly used emulsifier, polymerization initiator, hydrocarbon solvent, electrolyte, polymerization accelerator, chelating agent and the like can be used.

As the emulsifier, a sulfuric acid ester salt of a higher alcohol, an alkylbenzene sulfonate, an alkyl diphenyl ether sulfonate, an aliphatic sulfonate, an aliphatic carboxylate, an anionic surfactant such as a sulfuric acid ester salt of a nonionic surfactant, etc. Surfactants or nonionic surfactants such as an alkyl ester type of polyethylene glycol, an alkylphenyl ether type, an alkyl ether type and the like can be mentioned, and one or more of these can be used.

As the polymerization initiator, water-soluble polymerization initiators such as potassium persulfate, sodium persulfate and ammonium persulfate, redox type polymerization initiators and oil-soluble polymerization initiators such as benzoyl peroxide can be appropriately used. It is particularly 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, pentene, hexene, heptene, cyclopentene, cyclohexene, cycloheptene, 4-methylcyclohexene, 1-methylcyclohexene and the like. Hydrocarbon compounds such as saturated hydrocarbons, aromatic hydrocarbons such as benzene, toluene and xylene may be used. In particular, cyclohexene and toluene, which have an appropriately low boiling point and are easily recovered and reused by steam distillation after the completion of polymerization, are suitable.

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

If desired, modified starch such as starch, oxidized starch, esterified starch, natural binder such as soybean protein and casein, or 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 control the solid content of the polymer latex to be less than 50% by weight.
Furthermore, it is desirable to control it to less than 20% by weight, and it is most desirable to use the copolymer latex of the present invention alone.

In 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,
Silicone oil), leveling agent (funnel oil, dicyandiamide, urea, etc.), preservative, mold release agent (calcium stearate, paraffin emulsion, etc.), fluorescent dye, color water retention improver (carboxymethyl cellulose, sodium alginate, etc.) are required. You may add according to.

Further, as a method for applying the paper coating composition to the base paper for coating, any known technique such as an air knife coater, a blade coater, a roll coater or a bar coater may be used. It doesn't matter. After coating, the surface is dried and finished by calendering.

[0034]

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples as long as the gist thereof is not exceeded. In the examples, parts and percentages are by weight unless otherwise specified. The evaluation of various physical properties in the examples was based on the following methods.

[0035]Evaluation of dry pick strength of coated paper Tack value with relatively large division resistance using RI printer
Each coated paper sample was printed at the same time with 18 inks.
Grade 5 (best)
It was relatively evaluated from 1 to 1 (worst). 6 times stamp
A printing test was conducted and an average value was obtained.

[0036]Evaluation of wet pick strength of coated paper Each coated paper sample by Molton roll using RI printer
The dampening water is applied simultaneously to, and immediately after that, the division resistance
Is an ink with a medium tack value of 12 and each coated paper sample is the same.
Sometimes it is printed and the degree of picking at that time is judged with the naked eye
However, 5th grade (best) to 1st grade (worst)
Evaluated to. A printing test was conducted 6 times, and an average value was obtained.

[0037]Blank paper gloss measurement 7 for each coated paper sample according to JIS P-8142
A gloss of 5 ° was measured. The larger the number, the more glossy the white paper.
good.

[0038]Print gloss measurement Use a RI printer to print magenta on each coated paper sample.
Print process inks for fusset printing at the same time
After air-drying the ink, according to JIS P-8142
And a glossiness of 60 ° was measured. The larger the number, the printing light
The swamp is good.

[0039]Sucking swimsuit carnivorous Dampening water for each coated paper sample simultaneously using RI printer
Immediately after that, the process for black offset printing
Mark when the ink is printed on each coated paper sample at the same time
The printing density is judged with the naked eye, and the grade 5 (darkest) to grade 1 (maximum)
Even relatively thin). Printed 6 times
The average value was calculated.

[0040]Particle size measurement of copolymer latex The number average particle diameter was measured by the dynamic light scattering method. When measuring
Then use LPA-3000 / 3100 manufactured by Otsuka Electronics
did.

[0041]Measurement of gel content of copolymer latex Create a latex film in a room temperature atmosphere. afterwards
Weigh about 1g of latex film, 400cc
It is put in toluene and swelled and dissolved for 48 hours. afterwards,
This is filtered through a 300 mesh wire mesh and captured by the wire mesh.
The toluene-insoluble part was dried and weighed.
The ratio of the weight to the weight of the film is called the gel content.
And calculated in% by weight.

[0042]Residual α-methylstyrene in copolymer latex
Lendimer measurement Residual α-methylstyrene dimer in copolymer latex
-Is a gas chromatograph GC-14A manufactured by Shimadzu Corporation
Was performed by the following method. (1) Creating a sample 1 g of the copolymer latex was precisely weighed and N, N-dimethylpho
Dissolve it in 25 ml of Lumamide and leave it for 24 hours.
A fixed sample was used. (2) Gas chromatograph measurement conditions Sample volume: 5 μl Detector: FID Inj / Det temperature: 190 ° C Column temperature: 180 ℃ Column: Glass column 1.6m × 2.6mmφ Carrier: Chromosorb WAW DMCS (Grain size 80/100) Liquid phase: Silicone OV-17 Carrier gas: nitrogen, 25 ml / min. Hydrogen: 0.7 kg / cm2 Air: 0.9kg / cm2 (3) Quantitative method 2,4-diphenyl-4-methyl-1-pen of known concentration
Using the calibration curve prepared using Ten, the obtained gas
From the chromatograph to solid content of copolymer latex
Determination of 2,4-diphenyl-4-methyl-1-pentene
The value was determined as residual α-methylstyrene dimer. same
Measured three times for one sample and averaged in units of ppm Table 1
And 2.

The method for preparing the copolymer latex will be described below. The α-methylstyrene dimer used in preparing the copolymer latex was α-methylstyrene dimer manufactured by Goi Kasei Co., Ltd. and AMSD-GRH was used. AMSD-
GRH contains 97.0 to 98.0% of 2,4-diphenyl-4-methyl-1-pentene.

[0044]Preparation of copolymer latex 1 In a pressure-resistant polymerization reactor, add 140 parts of pure water and dough as an emulsifier.
Sodium decylbenzene sulfonate 0.7 parts, sodium carbonate
Charge 0.3 parts of thorium and 1 part of potassium persulfate.
After stirring, each of the monomers and α-meth
Cylstyrene dimer 0.9 parts, cyclohexene 2 parts
In addition, polymerization was initiated at 74 ° C. Polymerization temperature after 1.5 hours
The temperature is lowered to 72 ° C and maintained, and each monomer in the second step shown in Table 1
And t-dodecyl mercaptan 0.1 part, cyclohexyl
Sen 2 parts, potassium persulfate 0.4 parts, pure water 5 parts for 7 hours
Was added continuously over. Further raise the temperature to 75 ° C
After maintaining for 5 hours, the polymerization was completed. Polymerization at this time
The conversion rate was 96% or more. Then the copolymer LATEC
After adjusting the pH to about 7 with a caustic soda solution, steam
Unreacted monomers and other low boiling point compounds are removed by gas distillation.
Then, the copolymer latex 1 was obtained.

[0045]Preparation of copolymer latex 2 A pressure resistant polymerization reactor, 120 parts of pure water
Sodium decylbenzene sulfonate 0.4 parts, sodium carbonate
Charge 0.5 parts of thorium and 0.7 parts of potassium persulfate,
After sufficiently stirring, each of the first stage monomers shown in Table 1 and α
-Add 1 part of methylstyrene dimer and polymerize at 78 ° C.
Started. After 1 hour, lower the polymerization temperature to 75 ° C and keep it
Second-stage monomers and α-methylstyrene shown in Table 1
0.3 parts dimer, 0.5 parts potassium persulfate, dodecyl
0.1 part of sodium benzenesulfonate and 5 parts of pure water are added to 3 parts.
Added continuously over time. Then the polymerization temperature is set to 7
While maintaining the temperature at 5 ° C., each of the third stage monomers shown in Table 1 and
Sodium dodecylbenzene sulfonate 0.3 parts, pure water
5 parts were added continuously over 3.5 hours. further
After maintaining the temperature at 75 ° C. for 5 hours, the polymerization was completed. This
At that time, the polymerization conversion rate was 96% or more. Then co-weight
The combined latex is adjusted to a pH of about 7 with a caustic soda solution.
After removing the unreacted monomer by steam distillation,
A combined latex 2 was obtained.

[0046]Preparation of copolymer latex 3 In a pressure-resistant polymerization reactor, 110 parts of pure water and a demulsifier as an emulsifier
Sodium decylbenzene sulfonate 0.5 parts, sodium carbonate
Charge 0.3 parts of thorium and 0.9 parts of potassium persulfate,
After sufficiently stirring, each of the first stage monomers shown in Table 1 and α
-Add 1 part of methylstyrene dimer and polymerize at 73 ° C.
Started. After 1.5 hours, lower the polymerization temperature to 70 ° C and maintain.
Then, each monomer and n-octylmethene in the second stage shown in Table 1
0.2 parts of rucaptan, 0.2 parts of potassium persulfate, dodeci
0.1 parts sodium rubenzenesulfonate and 5 parts pure water
Added continuously over 2.5 hours. Then the polymerization temperature
While maintaining the temperature at 70 ° C, each monomer in the third step shown in Table 1
And 0.3 parts of potassium persulfate, dodecylbenzenesulfate
Sodium phonate 0.3 parts and pure water 5 parts in 4.5 hours
Freshly added continuously. Raise the temperature to 80 ℃
After maintaining for 5 hours, the polymerization was completed. Polymerization conversion rate at this time
Was 97% or more. Then, the copolymer latex
After adjusting the pH to about 7 with a caustic soda solution, steam distillation
The unreacted monomer is removed by
Obtained.

[0047]Preparation of copolymer latex 4 In a pressure-resistant polymerization reactor, add 100 parts of pure water and dough as an emulsifier.
Sodium decylbenzenesulfonate 0.6 parts, sodium carbonate
Charge 0.3 parts of thorium and 1.5 parts of potassium persulfate,
After sufficiently stirring, each of the first stage monomers shown in Table 1 and α
-Methylstyrene dimer 1.5 parts, t-dodecyl mel
0.1 part of captan was added and polymerization was initiated at 81 ° C. 1
After the time, the polymerization temperature was lowered to 77 ° C and maintained, and
Each monomer in the second stage and α-methylstyrene dimer 0.
6 parts, cyclohexene 2 parts, potassium persulfate 0.2 parts,
Sodium dodecylbenzene sulfonate 0.1 parts, pure water
10 parts were added continuously over 2.5 hours. That
While maintaining the post-polymerization temperature at 77 ° C, the third stage of Table 1
Monomers and sodium dodecylbenzene sulfonate
Add 0.3 parts and 5 parts of pure water continuously for 3.5 hours.
Added After maintaining at 77 ° C for 5 hours, polymerize
Finished. The polymerization conversion rate at this time was 96% or more.
It was Then, the copolymer latex is treated with a caustic soda solution.
After adjusting the pH to approximately 7, unreacted monomer is obtained by steam distillation.
And other low boiling point compounds removed, copolymer latex
Got 4.

[0048]Preparation of copolymer latex 5 Add 125 parts of pure water to the pressure resistant polymerization reactor and add as an emulsifier.
Sodium decylbenzene sulfonate 0.8 parts, sodium carbonate
Charge 0.3 parts of thorium and 1 part of potassium persulfate.
After stirring, each of the monomers and α-meth
Cylstyrene dimer 1 part, t-dodecyl mercaptan
Add 0.2 parts and 2 parts cyclohexene and polymerize at 75 ° C.
Started. After 1.5 hours, lower the polymerization temperature to 73 ° C and maintain.
Then, each of the second stage monomers shown in Table 1 and potassium persulfate
0.5 parts and 10 parts of pure water are continuously added over 3 hours.
did. Then, while maintaining the polymerization temperature at 73 ℃, shown in Table 1.
3rd stage monomer and cyclohexene 1 part, pure water 5
Parts were added continuously over 4 hours. Further temperature
After the temperature was raised to 75 ° C. and kept for 6 hours, the polymerization was completed. this
The polymerization conversion rate at that time was 96% or more. Then copolymerization
The body latex was adjusted to about pH 7 with a caustic soda solution.
After that, steam distillation reduces unreacted monomers and other boiling points
The compound was removed to obtain a copolymer latex 5.

[0049]Preparation of copolymer latex 6 In a pressure-resistant polymerization reactor, 115 parts of pure water and a dough as an emulsifier
Sodium decylbenzene sulfonate 0.5 parts, sodium carbonate
Charge 0.5 parts of thorium and 0.9 parts of potassium persulfate,
After thoroughly stirring, add each monomer in the first step shown in Table 2
Polymerization was initiated at 70 ° C. After 2 hours, the polymerization temperature is 65 ° C.
And kept at a low temperature, and each monomer and α-in the second stage shown in Table 2
Methylstyrene dimer 0.5 part, potassium persulfate 0.
3 parts, sodium dodecylbenzene sulfonate 0.2
Parts, and 10 parts of pure water were continuously added over 7 hours.
After further raising the temperature to 70 ° C and maintaining it for 4 hours, the polymerization was terminated.
Finished. The polymerization conversion rate at this time was 96% or more. Next
PH of the copolymer latex with caustic soda solution.
After adjusting to about 7, unreacted monomer is removed by steam distillation
Then, a copolymer latex 6 was obtained.

[0050]Preparation of copolymer latex 7 In a pressure-resistant polymerization reactor, add 100 parts of pure water and dough as an emulsifier.
Sodium decylbenzene sulfonate 0.8 parts, sodium carbonate
Charge 0.4 parts of thorium and 0.8 parts of potassium persulfate,
After thoroughly stirring, add each monomer in the first step shown in Table 2
Polymerization was initiated at 68 ° C. 2 shown in Table 2 after 1.5 hours
Each monomer in the second stage and α-methylstyrene dimer 0.
5 parts, potassium persulfate 0.3 parts, dodecylbenzenesulfate
Sodium phonate 0.1 part, pure water 5 parts over 3 hours
And added continuously. Then raise the polymerization temperature to 70 ° C
Keep each of the third stage monomers and α-methyls shown in Table 2.
1 part of ethylene dimer, sodium dodecylbenzene sulfonate
0.1 parts of helium and 5 parts of pure water continuously over 4 hours
Was added. After maintaining at 70 ℃ for 3 hours,
The meeting was finished. The polymerization conversion rate at this time was 96% or more.
It was Then, the copolymer latex is treated with a caustic soda solution.
After adjusting the pH to approximately 7, unreacted monomer is obtained by steam distillation.
Was removed to obtain a copolymer latex 7.

[0051]Preparation of copolymer latex 8 In a pressure-resistant polymerization reactor, add 160 parts of pure water and dough as an emulsifier.
Sodium decylbenzene sulfonate 0.8 parts, sodium carbonate
Charge 0.4 parts of thorium and 1 part of potassium persulfate, sufficient
After stirring, each monomer and α-medium in the first stage shown in Table 2 were mixed.
Add 0.2 parts of chill styrene dimer and polymerize at 72 ° C.
Started. After 1.5 hours, lower the polymerization temperature to 70 ° C and maintain.
Then, each monomer and α-methylstyrene in the second stage shown in Table 2
0.2 parts of Rendimer, t-dodecyl mercaptan 0.
1 part, potassium persulfate 0.2 part, dodecylbenzenesul
Sodium phosphonate 0.1 parts, pure water 10 parts over 3 hours
Was added continuously. Then raise the polymerization temperature to 72 ° C
And each of the third stage monomers and α-methyl shown in Table 2
Styrene dimer 0.8 parts, t-dodecyl mercaptan
0.1 part, potassium persulfate 0.3 part, dodecylbenzene
Sodium sulfonate 0.1 parts, pure water 5 parts 3.5 hours
Was added continuously over. Furthermore, the temperature remains at 72 ℃
After maintaining for 3 hours, the polymerization was completed. Polymerization conversion rate at this time
Was over 96%. Then the copolymer latex
After adjusting the pH to about 7 with an aqueous solution of caustic soda, steam steaming
Unreacted monomers are removed by distillation to obtain a copolymer latex 8
Got

[0052]Preparation of copolymer latex 9 In a pressure-resistant polymerization reactor, 115 parts of pure water and a dough as an emulsifier
Sodium decylbenzene sulfonate 1 part, potassium persulfate
1.5 parts of Um was charged, and after sufficiently stirring, 1 shown in Table 2
Each monomer in the second stage and α-methylstyrene dimer 0.
73 parts by adding 2 parts and 0.1 part of t-dodecyl mercaptan
Polymerization was initiated at ° C. Second stage shown in Table 2 after 1.5 hours
Each monomer and α-methylstyrene dimer 0.3
Part, t-dodecyl mercaptan 0.1 part, potassium persulfate
0.2 parts of sodium, sodium dodecylbenzene sulfonate
0.3 parts and 10 parts of pure water are continuously added over 4 hours.
did. After that, the polymerization temperature was raised to 75 ° C and maintained, and
Third-stage monomers and α-methylstyrene dimer
2.5 parts 0.9 parts, 0.2 parts potassium persulfate, 5 parts pure water
Added continuously over time. Furthermore, the temperature of 75 ℃
After keeping the same for 4 hours, the polymerization was terminated. Polymerization at this time
The conversion rate was 96% or more. Then the copolymer LATEC
After adjusting the pH of the soot to about 7 with an aqueous solution of caustic soda, steam
Unreacted monomer is removed by distillation, copolymer latex
Got 9.

[0053]Preparation of copolymer latex 10 In a pressure-resistant polymerization reactor, add 130 parts of pure water and dough as an emulsifier.
Sodium decylbenzene sulfonate 0.7 parts, persulfate
After 0.7 part of potassium was charged and sufficiently stirred, the results are shown in Table 2.
First-stage monomers and α-methylstyrene dimer
66 parts by adding 2 parts of t-dodecyl mercaptan
Polymerization was initiated at ° C. After 2 hours, each of the second stage shown in Table 2
Monomer and 1 part of α-methylstyrene dimer, t-do
Decyl mercaptan 0.3 parts, potassium persulfate 0.5
Part, 0.2 part of sodium dodecylbenzene sulfonate,
5 parts of pure water was continuously added over 3 hours. afterwards
The polymerization temperature was raised to and maintained at 72 ° C.
Monomer and potassium persulfate 0.3 parts, pure water 5 parts at 4 o'clock
It was added continuously over a period of time. Furthermore, the temperature of 72 ℃
After maintaining for 3 hours, the polymerization was completed. Polymerization conversion at this time
The rate was 96% or more. Then the copolymer latex
After adjusting the pH to about 7 with an aqueous solution of caustic soda, steam steaming
Unreacted monomer is removed by distillation to obtain copolymer latex 1
I got 0.

[0054]Preparation of copolymer latex 11 In a pressure-resistant polymerization reactor, 110 parts of pure water and a demulsifier as an emulsifier
Sodium decylbenzene sulfonate 0.5 parts, sodium carbonate
Charge 0.4 parts of thorium and 0.8 parts of potassium persulfate,
After sufficiently stirring, each of the first stage monomers shown in Table 2 and α
-0.7 parts of methyl styrene dimer, t-dodecyl mel
0.1 part of captan was added and polymerization was initiated at 78 ° C. 1
After the time, the polymerization temperature was lowered to and maintained at 75 ° C.
Each monomer in the second stage and α-methylstyrene dimer 0.
2 parts, t-dodecyl mercaptan 0.2 parts, cyclohex
Sen 2 parts, potassium persulfate 0.5 parts, dodecylbenzene
Sodium sulfonate 0.3 parts, pure water 5 parts for 6.5 hours
Was added continuously over. Furthermore, the temperature remains at 75 ℃
After maintaining for 5 hours, the polymerization was completed. Polymerization conversion rate exceeds 94%
Polymerization was completed at the time. Then the copolymer LATEC
After adjusting the pH of the soot to about 7 with an aqueous solution of caustic soda, steam
Removal of unreacted monomers and other low boiling compounds by distillation
Then, a copolymer latex 11 was obtained.

[0055]Preparation of copolymer latex 12 In a pressure-resistant polymerization reactor, add 130 parts of pure water and dough as an emulsifier.
Sodium decylbenzenesulfonate 0.6 parts, sodium carbonate
Charge 0.3 parts of thorium and 1.3 parts of potassium persulfate,
After sufficiently stirring, each of the first stage monomers shown in Table 2 and α
-Add 0.5 parts of methyl styrene dimer and add heavy at 75 ° C.
It started to work. After 2 hours, each monomer in the second stage shown in Table 2
And 0.5 part of α-methylstyrene dimer, t-dode
0.3 parts of silmercaptan, 0.1 part of potassium persulfate,
Sodium dodecylbenzene sulfonate 0.2 parts, pure water
5 parts were added continuously over 3.5 hours. afterwards
The polymerization temperature was raised to and maintained at 80 ° C.
Monomer and 0.1 parts potassium persulfate, dodecylbenze
Sodium sulfonate 0.2 parts, pure water 5 parts in 3 hours
Was continuously added over. Furthermore, the temperature remains at 80 ℃. 5
After the time was maintained, the polymerization was completed. The polymerization conversion rate at this time is
It was 96% or more. Then, the copolymer latex is
After adjusting the pH to about 7 with a caustic soda solution, steam distillation
The unreacted monomer is removed to obtain the copolymer latex 12.
Obtained.

[0056]Preparation of copolymer latex 13 A pressure resistant polymerization reactor, 120 parts of pure water
Sodium decylbenzene sulfonate 0.5 parts, sodium carbonate
Charge 0.5 parts of thorium and 0.5 parts of potassium persulfate,
After sufficiently stirring, each of the first stage monomers shown in Table 2 and α
-Add 0.5 parts of methylstyrene dimer and add heavy at 72 ° C.
It started to work. After 2 hours, raise the polymerization temperature to 75 ° C
Then, each monomer and potassium persulfate in the second step shown in Table 2
0.6 part, sodium dodecylbenzene sulfonate 0.
2 parts and 10 parts of pure water were continuously added over 7 hours.
It was After maintaining the temperature at 75 ° C for 5 hours, the polymerization was terminated.
Finished. The polymerization conversion rate at this time was 96% or more. Next
PH of the copolymer latex with caustic soda solution.
After adjusting to about 7, unreacted monomer is removed by steam distillation
Then, a copolymer latex 13 was obtained.

[0057]Preparation and evaluation of paper coating composition According to the formulation shown below, copolymer latex 1
~ 13 is used, the type of copolymer latex is different.
13 types of paper coating compositions were prepared.

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

[0059]Production and evaluation of coated paper Using a commercially available hot air coating dryer MLC-100S type,
The amount of 82 g / m @ 2 coated base paper coated with each of the obtained paper
The composition was coated to prepare 12 types of coated papers. In addition,
All coated papers were produced under the same conditions shown below. Coating conditions: The hot air coating dryer described above is used to remove the above composition.
Wire coat so that the dry coating amount is 15g / m2 on one side.
Was used for coating. The coating speed is 46 m / min. Set up
Decided Drying condition: About 0.5 seconds after coating, 150 ° C drying oven
5 seconds with hot air at a temperature of 210 ° C and a wind speed of 33 m / sec.
Dried. Each of the coated papers obtained was stripped at a relative humidity of 65% and a temperature of 20 ° C.
After adjusting the humidity all day and night under conditions, linear pressure 80kg / cm, temperature 6
0 ° C, paper passing speed 7m / min, 2 times for each front and back, 4 times
Super calendered under the conditions, copolymer latex
13 types of coated papers having different values were obtained. Each of the obtained coated paper
It was subjected to a test and evaluated, and the result was evaluated for the copolymer latex.
Particle size, gel content, residual α-methylstyrene dimer
The amounts are shown in Tables 1 and 2.

[0060]

[Table 1]

[0061]

[Table 2]

[0062]

EFFECT OF THE INVENTION By using the copolymer latex for coating offset printing paper of the present invention, a coated paper for offset printing having an excellent balance of surface strength, printing gloss, and fleshness of swimwear is provided. Is.

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) C08L 9/00-21/02

Claims (2)

(57) [Claims] 1. An aliphatic conjugated diene monomer 28 to 60% by weight and an ethylenically unsaturated carboxylic acid monomer 1 to 10% by weight.
And 100 parts by weight of a total of 30 to 71% by weight of another monomer copolymerizable therewith by emulsion polymerization in the presence of 0.8 to 2.5 parts by weight of α-methylstyrene dimer. In the obtained copolymer latex, the α-methylstyrene dimer remaining in the copolymer latex is 800 to 2 relative to the solid content of the copolymer latex.
Copolymer latex for coating offset printing paper, characterized in that it is 500 ppm. 2. A composition for coating offset printing paper, which comprises the copolymer latex according to claim 1.