JPS6059192A - High solid concentration coating composition - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel paper coating composition, and more particularly, it relates to a novel composition for coating paper, and more particularly, it contains an aliphatic conjugated diolefin monomer, a vinyl cyanide monomer, and an ethylenically unsaturated monomer. γC is also obtained by emulsion copolymerization of Iki 17 So 1 T Mei 1 monomer and relates to a cyanide compound.

In the coated paper industry, increasing the solid content of coating fluids is being promoted in order to reduce manufacturing costs, and the main methods are increasing the amount of calcium carbonate and reducing the amount of natural water-soluble binders such as casein and starch. are carried out singly or in combination. However, with either of these methods, the stiffness of the coated paper, that is, the so-called paper stiffness, may be significantly reduced. In addition, it has become clear that printing gloss decreases as the amount of calcium carbonate increases and becomes finer, and there is an urgent need to solve this problem. Also,
It is even more difficult to maintain strength while satisfying these physical properties. To solve these problems, it has been proposed to use vinyl cyanide monomers as a binding material.

For example, JP-A-50-94034 discloses aliphatic conjugated diolefin monomers, ethylenically unsaturated carboxylic acid monomers, vinyl cyanide monomers, and other monoolefins copolymerizable with these monomers. A synthetic copolymer latex obtained by emulsion copolymerization of monomers is disclosed, and is described as being particularly excellent as a binder for coated paper for off-circle printing. It is said to have a good balance of physical properties such as blister resistance, ink holdout, printed surface gloss (ink cross), water resistance, and adhesiveness.

On the other hand, JP-A-57-176297 uses calcium carbonate and vinyl cyanide monomers having a specific particle size distribution as components of a coating composition for coated paper having a solid content concentration of 65 to 80% by weight. A combination of copolymer latexes is disclosed.

However, the inventions described in these publications do not describe any characteristics regarding the emulsion copolymerization method of vinyl cyanide monomers. However, there remains a technical problem in that problems such as paper stiffness and print gloss may become worse depending on the usage of vinyl cyanide monomers.

The present inventors have conducted intensive studies with the aim of obtaining a paper coating composition that can dramatically improve the printed surface gloss of coated paper and the like, while also maintaining adhesive strength and rigidity at a high level. A characteristic copolymer latex can only be obtained when vinyl cyanide monomers are polymerized under certain specific emulsion copolymerization conditions, and when this latex is used as a bonding material, the desired paper coating composition can be obtained. The present invention was developed based on the discovery that it is possible to provide a product.

That is, in the present invention, for 100 parts by weight of the pigment for paper coating, as a binder, an aliphatic conjugated diolefin monomer (Al cyanide vinyl monomer (b) 3 to 20 weight percent diethylene unsaturated Carboxylic acid monomer content: 105 to 8% by weight (al to fbl copolymerizable with (C), ethylenically unsaturated monomers other than (cl) (di, ao to 75% by weight)
obtained by emulsion polymerization of vinyl cyanide monomer (
contains 6 to 25 parts by weight of a copolymer latex obtained by continuous or sequential addition polymerization of at least 65% by weight of the total monomers as a monomer mixture; A composition for coating paper with a high solid content concentration, characterized in that the solid content concentration is 65 to 75% by weight.

In the present invention, the monomers contain the entire amount of the monomers (at to (obtained by emulsion polymerization of dl and are vinyl cyanide monomers), and at least 65% by weight of the total monomers are monomers. It is characterized in that a copolymer latex obtained by continuously or sequentially adding and polymerizing a mixture to a polymerization system is used as a binder.

Among the monomer components used, aliphatic conjugated diolefin monomers [a] include 1,3-butadiene, 2-methyl-1,6-butadiene, and 2,3-dimethyl-1,3-
Phtadiene, 2-neopentyl-1゜6-butadiene,
2-chloro-1,6-butadiene, 2-cyano-1,3
-butadiene, substituted straight-chain conjugated pentagenes, straight-chain and side-chain conjugated hexadiene, and the like. 1 of these,
Particular preference is given to using 3-butadiene. These monomers are used in an amount of 20 to 36% by weight in order to appropriately balance flexibility and stiffness of the copolymer.

If the amount of monomer (a) used is less than 20% by weight, the flexibility of the coated paper will be insufficient and the adhesive strength will particularly decrease significantly;
If the weight percentage is exceeded, the stiffness will be insufficient.

Examples of the hepta-anide vinyl monomer (b) include aliphatic unsaturated nitrides such as acrylonitrile, methacrylaterile, α-chloroacrylonitrile, and α-ethyl acrylonitrile.

Particular preference is given to using these acrylonitriles.

These vinyl cyanide monomers are used in a weight range of 3 to 20 in order to obtain good stiffness and print gloss. If the amount of monomer [b) used is less than 6% by weight, the stiffness of the coated paper
The printing gloss is insufficient, and on the other hand, when the weight ratio exceeds 20, the adhesive strength decreases significantly. More preferably, suitable results are obtained when the weight ratio is 5 to 15.

Ethylenically unsaturated carboxylic acid monomers (as Cl, acrylic acid, methacrylic acid, itaconic acid, fumaric acid are preferably used, but in addition, dicarboxylic acid anhydrides or dicarboxylic acid monoalkyl esters, etc.) These can be used alone or in combination.

These ethylenically unsaturated carboxylic acid monomers (Cl is 0.5 to 8 to improve adhesive strength and impart mechanical stability)
Used within the weight range.

If the amount of the monomer (C1) used is less than 0.5% by weight, the adhesive force will be low and the mechanical stability of the coated paper will be insufficient, while if it exceeds 8% by weight, problems with polymerization stability and coating problems may occur. Operational problems arise due to thickening of the composition.

Copolymerizable with the above monomers (a) to (c) (bl,
Ethylenically unsaturated monomers other than (c) (dl include aromatic vinyl monomers such as styrene, α-methylstyrene, vinyltoluene, dimethylstyrene, methyl acrylate, ethyl acrylate, butyl acrylate, 2- Acrylic acid ester monomers such as ethylhexyl acrylate, lauryl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, glycidyl acrylate, methyl methacrylate, ethyl methacrylate, 2-hydroxyethyl methacrylate, 2- and droxypropyl methacrylate,
Methacrylic acid ester monomers such as glycidyl methacrylate, acrylamide monomers such as acrylamide, N-methylolacrylamide, N-butoxymethylacrylamide, methacrylamide monomers such as methacrylamide, N-methylolmethacrylamide, etc. can be mentioned. Koishi 1' /7+l l'l beg
Particularly preferred is the use of ``mate 1 non'' - te ru shi 〃 1 ji no. These monomers can be used alone or in combination of two or more, but are preferably used in an amount of 40 to 75% by weight.

In order to obtain the copolymer latex applicable to the present invention, vinyl cyanide monomer (b) is particularly selected from among the monomer compositions mentioned above.
It is necessary to carry out addition polymerization continuously or sequentially as a monomer mixture containing a total amount of at least 65% by weight, preferably at least 70% by weight of the total monomers. Vinyl cyanide monomer (2) is not conjugated with conjugated diolefin monomer (a) or ethylenically unsaturated monomer (fcl) unless special measures are taken in the polymerization method specified in the present invention. It does not polymerize and forms a copolymer with a high cyanide vinyl monomer content that is far from the total monomer composition, resulting in non-uniform composition of the copolymer, which affects physical properties, especially adhesive strength and print gloss. It became clear that it had a negative impact. In order to prevent this, it is necessary to employ a specific polymerization method as described above.

If vinyl cyanide monomer (BL) is used all at once, the above-mentioned problem will occur, so it is necessary to add it continuously or sequentially to the polymerization system, but in this case, at least 65% by weight of the total monomer If the amount is less than 65% by weight, it is difficult for the vinyl cyanide monomer to copolymerize with other monomers, and the effect described above is small.

Thus, the copolymer latex applied to the present invention has a uniform composition in which the monomers (a) to id) are substantially copolymerized according to the monomer composition. There is no upper limit to the ratio at the time of addition polymerization, and a ratio of 100% by weight is possible, but it is better that the ethylenically unsaturated carboxylic acid monomer (fc) is present in part or in full in advance in the 1-merization system at the start of polymerization. Since a copolymerized latex with good physical properties can be obtained, the upper limit is preferably 95% by weight.

The addition rate of the monomer mixture to the polymerization system is preferably 35 parts by weight/based on 100 parts by weight of the polymerization recipe.
The amount is preferably not more than 14 parts by weight/hour, more preferably not more than 14 parts by weight/hour.

Further, when adding the monomer mixture to the polymerization system, the liquid state may be such that the mixture may be dissolved as it is, or may be emulsified in advance with an emulsifier to form an emulsion.

The particle size of the copolymer latex applied to the present invention is 0.
08-0.18 ttm, preferably 0.10-0.
Particle size of 15 μm, its gel content is 65-95% by weight,
It is preferably in the range of 45 to 85 weight percent.

If the particle size of the copolymer latex is less than 0.08 μm, the viscosity of the copolymer latex will increase, while if it exceeds 0.18 μm, water resistance, adhesiveness, and fluidity will decrease.

If the gel content of the copolymer latex is less than 65% by weight, the adhesiveness will be poor, while if it exceeds 95% by weight, the blister resistance and water resistance will be poor.

In order to obtain the copolymer latex of the present invention, chain transfer agents, emulsifiers, and polymerization initiators used in ordinary aqueous emulsion polymerization are used.

As a chain transfer agent, octyl mercaptan, n-dodecyl mercaptan + tert-dodecyl mercaptan,
n-hexadecyl mercaptan, ter t-hexadecyl mercaptan, n-tetradecyl mercaptan, t
Mercaptans such as ert-tetradecyl mercaptan, hydrocarbons such as tetraethylthiuram sulfide, carbon tetrachloride, ethylene bromide and pentaphenylethane, or acrolein, methacrolein, allyl alcohol, 2-ethylhexyl thiocricolate, etc. can give. These chain transfer agents can be used alone or in combination of two or more. The method of use may be one-time addition, divided addition, or continuous addition.

As the emulsifier, so-called anionic surfactants are preferably used, such as higher alcohol sulfate ester salts, alkylaryl sulfonates, higher alcohol (poly)ethylene oxide efonates, alkyl succinate sulfonates, Alkaline salt of phosphoric acid mono(or di)ester of (poly)ethylene oxide of higher alcohol,
Examples include sulfuric acid esters and phosphoric acid ester salts of nonionic surfactants.

It is also possible to use nonionic surfactants such as polyoxyethylene alkylphenol ether and fatty acid ester of polyethylene glycol in combination with anionic surfactants.

As the polymerization initiator, inorganic peroxides such as persulfates and hydrogen peroxide, organic peroxides such as cumenohydronochloride oxide, lauroyl peroxide, and diimbutylbenzoyl peroxide, and furthermore, the above-mentioned oxidation catalyst and Examples include so-called redox catalysts used in combination with reducing agents such as sodium sulfite and sulfonate of formaldehyde.

Furthermore, during the emulsion copolymerization of the copolymer latex, it is of course possible to use various snow melting polymerization accelerators, chelating agents, etc. in a wide variety of ways.

Although high temperature polymerization is generally preferred from the viewpoint of polymerization time and polymerization rate, low temperature polymerization using a redox catalyst is also possible. It is also possible to stop the polymerization using a polymerization terminator during the polymerization, if necessary.

The copolymer latex thus obtained is usually added with a basic substance so as to have a pH of 4 or more in order to improve stability, and subjected to a step of removing unreacted monomers and a step of concentrating, before being subjected to the present invention.

As the paper coating pigment used in the present invention, mineral pigments commonly used for paper coating are generally effective. For example, various clays, aluminum hydroxide, titanium dioxide, satin white, precipitated barium sulfate, calcium carbonate, etc. can be used. These may be used alone or in combination. Clays include kaolinite, hydrated halloysite, sericite, and pyrophyllite, and kaolinite is preferred for coated paper. Further, as calcium carbonate, either heavy or light calcium carbonate can be used, but finely divided calcium carbonate having an average particle size of 0.1 to 1.5 μm is particularly preferable. When used in an amount of % by weight or more, the characteristics of the copolymer latex of the present invention are maximized.

As the binder component used in the present invention, the pigment 10
3 to 2 parts of the copolymer latex of the present invention per 0 parts by weight
It is preferable to use 5 parts by weight, especially 3 to 15 parts by weight, and other binders such as starch, casein, polyvinyl alcohol can also be used in combination.

If the latex is less than 3 parts by weight per 100 parts of the pigment, the printed surface gloss of the coated paper will not improve and the adhesive strength will deteriorate.
The stiffness is also insufficient, and on the other hand, if it exceeds 25 parts by weight, the smoothness will decrease.

In addition to the above, the coating composition of the present invention includes a mold release agent such as calcium stearate, ammonium stearate, and wax emulsion, a water resistance agent such as glyoxal, melamine-formaldehyde resin, and urea-formaldehyde resin, and a foaming agent. It can contain commonly used agents such as surfactants and dispersants.

The total solid concentration of the coating composition of the present invention is 63 to 753
~75 parts by weight will have a significant effect or even 65 to 7 parts by weight
Suitable results can be obtained from 0.05 to 70 parts by weight.

If the total solids concentration is less than 63% by weight, the properties such as printed surface gloss of the coated paper will not be improved, and if it exceeds 75% by weight, the concentration will be too high and cannot be applied to the process.

As is clear from the purpose of the present invention, the coating composition according to the present invention can dramatically improve the gloss of the printed surface of coated paper, and can maintain adhesive strength and rigidity at high levels.

EXAMPLES Next, examples will be given to explain the present invention in more detail, but the present invention is not limited in any way by these examples. In addition, all parts and parts described are not particularly specified] Shooting book, Kagyo V castle ax - In addition, in the examples, average particle size, gel content, low shear viscosity,
High shear viscosity, dry pick, wet pick, print gloss and paper stiffness were determined as follows:

<Average particle size> Average particle size of 500 particles obtained by observing latex treated with osmic acid using an electron microscope.

<Gel content> The latex was adjusted to pH 8, the copolymer in the latex was coagulated with an impropat tool, and the solid content of 0.3 F obtained by washing and drying was immersed in 100 d of toluene at room temperature for 20 hours. The weight ratio of the remaining solids obtained by subsequent filtration through a 120-mesh wire mesh to the total solids.

Low shear viscosity> The viscosity of the coating composition under low shear rate measured by a BP viscometer (Tokyo Keiki Seisaku Kaisha).

High shear viscosity〉 Vercules High Shear Viscometer [MODEL
Viscosity of the coating composition under high shear rate measured by -ni-2DJ (manufactured by Kumagai Riki Kogyo Co., Ltd.).

<Dry Pick> For coated paper, ink (TV,...
, 14), the picking condition of the printed surface was judged with the naked eye after overprinting six times, and the results were evaluated on a scale of 5 points (the higher the number, the better).

<Wet pick> For coated paper, water is supplied using a Molton roll using a type I printing machine, and immediately after that, printing is performed using an R1 type printing machine with ink ('rV = 103, and the picking state of the printed surface is A value determined by the naked eye and evaluated on a 5-point scale (the higher the value, the better).

<Printing gloss> For coated paper I (ink amount 0.2 using I type printing machine)
After printing with CC, leave it for 24 hours and measure the printed surface with a Murakami glossy needle.

<Paper stiffness> Value measured using a Gurley stiffness meter (the higher the value, the harder it is).

<Production of copolymer latex ■> 160 parts of water, 0 parts of sodium alkylbenzenesulfonate
．． 5 parts of sodium bicarbonate, 0.6 parts of sodium hydrogen carbonate, and 0.5 parts of potassium persulfate were charged into an autoclave having a capacity of 100 tons.

Next, monomers consisting of 4 parts of butadiene, 13 parts of styrene, 5 parts of methyl methacrylate, 1 part of acrylic acid, and 2 parts of fumaric acid were added all at once, and the mixture was charged with 6 parts of carbon tetrachloride.
The mixture was heated to 70°C while stirring to initiate polymerization.

After 2 hours, uniform continuous addition of a monomer mixture consisting of 22 parts of butadiene, 40 parts of styrene, 5 parts of methyl methacrylate, and 8 parts of acrylonitrile was started, and the polymerization was continued for 15 hours, reaching a polymerization conversion of 100 parts. . The resulting copolymer latex had a good polymerization pattern and little coagulation.

A sodium hydroxide solution was added to this copolymer latex to adjust the pH to 7, followed by monomer stripping and vacuum distillation to concentrate. The obtained copolymer latex is referred to as Latex I.

<Production of copolymer latex A> Polymerization was started in exactly the same manner as copolymer latex I.
After that time, uniform continuous addition of a monomer mixture consisting of 22 parts of butadiene, 40 parts of styrene, 5 parts of methyl methacrylate, and 4 parts of acrylonitrile was started, and after the polymerization was continued for 14 hours, 4 parts of acrylonitrile was added alone for 1 hour. Cotton was continuously added and polymerized (single addition). The copolymer latex obtained at a polymerization conversion rate of 99% had a good polymerization mode and little coagulation. This copolymer latex was treated in the same manner as latex I to obtain copolymer latex A.

Production of copolymer latex B> 160 parts of water - 0 parts of sodium alkylbenzenesulfonate
．． 4 parts, sodium hydrogen carbonate 0.4 parts, Kakuma-/11
6 parts of 1 um was charged into an autoclave with a capacity of 100 tons. Next, 4 parts of butadiene, 9 parts of styrene, 5 parts of methyl methacrylate, 4 parts of acrylonitrile, 1 part of acrylic acid
A monomer consisting of 2 parts of fumaric acid and 6 parts of carbon tetrachloride was added all at once, and the mixture was heated to 70° C. with stirring to initiate polymerization. After 2 hours, uniform continuous addition of a monomer mixture consisting of 4 parts of butadiene, 44 parts of styrene, 5 parts of methyl methacrylate, and 4 parts of acrylonitrile was started, and the polymerization was continued for 15 hours, reaching a polymerization addition rate of 100 parts. . The obtained copolymer latex had a good polymerization pattern and little coagulation. This copolymer latex was treated in the same manner as latex ① to obtain copolymer latex B.

<Production of copolymer latexes 1 to 2, C-I> Copolymer latexes 1 to 2 having the monomer compositions shown in Tables 1 and 2 were obtained in the same manner as for copolymer latex I. Similarly, copolymer latexes C to ① were obtained.

The monomer composition, average particle diameter, and gel content of copolymer latexes I~① and A~ are shown in Tables 1 and 2.

Examples 1-9. Comparative Examples 1 to 9 A coating composition having the following formulation was prepared using one length of the copolymer latex obtained above, and after coating, drying and finishing, the coated paper was evaluated. The results obtained are shown in Table 3.

Coating composition formulation (parts by dry weight) Mineral pigment kaolin clay (UW-9030 manufactured by EM&C Co., Ltd. Calcium carbonate (CARBITAL-90 manufactured by Fuji Kaolin Co., Ltd. Average particle size approximately 0.6 μm) 0 Binder copolymer latex 12 Dispersion agent Sodium polyacrylate (Aron T-4o manufactured by Toagosei Co., Ltd.) 0.1 Total solid content 67% From the above results, the example of the present invention (Latext ■) had good results for all properties. is,
It was found that the printability and paper stiffness were well balanced.

On the other hand, the comparative examples (latex A to ■) had poor balance in some of the properties.

Patent applicant: Japan Synthetic Rubber Co., Ltd. Representative Patent Attorney Shigetaka Shirai Procedural amendment (method) % formula % 1. Indication of the case Patent Application No. 1626/1/1 1982 2. Name of the invention High solids concentration paper Coating Composition 3, Relationship with the Amendment Case Patent Applicant Address 2-11-24 Tsukiji, Chuo-ku, Tokyo Name (4)
17) Japan Synthetic Rubber Co., Ltd. Representative: Hisashi Yoshimitsu 4 Agent: 107 Address: Room 315, Palais Royal Akasaka, 2-17-54 Akasaka, Minato-ku, Tokyo %1 Column Z of “Detailed Description of the Invention” in the Specification Amendment Pages 24, 25, and 27 (all full texts) of the specification of contents are amended as shown in the attached sheet.

Claims (1)

[Scope of Claims] 1. For 100 parts by weight of pigment for paper coating, as a binder, aliphatic conjugated diolefin monomer (a120-36 weight ratio vinyl cyanide monomer (b) 3-20 wt% ethylenically unsaturated carboxylic acid monomers (ClO 15-8 wt% (a) - copolymerizable with fcl (bl, (d) ethylenically unsaturated monomers other than cl 40-75 wt%) Obtained by emulsion copolymerization and containing vinyl cyanide monomer (
bl and 3 to 25 parts by weight of a copolymer latex obtained by continuous or sequential hexapolymerization as a monomer mixture of at least 65% by weight of the total monomers, and Solid content concentration is 63 to 753 to 75 parts by weight 2,
The copolymer latex contains: 1.3 butadiene (a) 20-36 weight ratio acrylonitrile (w) 5-15 weight ratio lyacrylic acid At least one selected from acrylic acid, itaconic acid and fumaric acid.
Ethylenically unsaturated carboxylic acid (C) 1-51% styrene and/or methyl methacrylate Tdl
The high solids concentration paper coating composition according to claim 1 obtained by copolymerization with a weight ratio of 45 to 70. 3. For coating high solid content paper according to claim 1 or 2, wherein the copolymer latex has a particle size of 0.08 to 0.18 μm and an amount of 35 to 955 to 95 parts by weight. Composition.