JPH01111092A - Paper coating binder - Google Patents

Abstract

PURPOSE: To obtain a binder for paper coating having each specific minimum melt adhesion temperature of dried polymer particles and gel fraction of a membrane and aiming at the improvement of a gloss, non-adhesive property and printing adoptability of a coated paper by polymerizing specific components such as styrene, etc., in a specific ratio. CONSTITUTION: This binder for paper coating is obtained by performing an emulsion polymerization of (A) 30-69.5 wt.% styrene, (B) 30-60 wt.% 2-8C alkyl acrylate (preferably ethyl acrylate, etc.), and (C) 0.5-10 wt.% ethylenically unsaturated carboxylic acid (preferably acrylic acid, etc.), to obtain a polymer latex having 35-70 deg.C minimum melt adhesion temperature and 0-40 wt.% gel fraction in its membrane. It is preferable to mix the above latex with a conventional SB-based latex in (25:75)-(70:30) dried weight ratio and use as the binder for paper coating.

Description

Detailed Description of the Invention Industrial Application Fields The present invention relates to a binder for paper coating, and more specifically, the present invention relates to a paper coating binder, and more specifically, by using the polymer latex of the present invention as a paper coating binder. The gloss and non-stickiness of coated paper can greatly improve its printability, and coated paper,
Provides materials useful to the coated paperboard manufacturing industry.

<Prior art and their points of interest> Coated paper and coated paperboard (hereinafter collectively referred to as coated paper) are made by papermaking for the purpose of improving the printability of the paper and the characteristic characteristics such as gloss. Kaolin clay, carunium carbonate, satin white, aluminum hydroxide,
Water-dispersed paints containing inorganic pigments such as titanium oxide, Merck, and magnesium hydroxide, their polymer latex as a binder, water-retaining agents, and water-bathable polymers such as starch and casein as auxiliary binders. The coating creates folds.

Among the polymer latexes used as the main binder, styrene-butadiene monopoly latex (hereinafter referred to as T) is used as the polymer latex.
(referred to as SB latex) is used.

By the way, in the case of coated paper, the same characteristic of white paper gloss as the characteristic of the nine characters is a significant charge. This is because the appearance after printing is significantly improved by increasing the white paper gloss. Conventionally, in order to increase the white paper gloss, methods have been considered to reduce the amount of binder added to the pigment in paints, or to lower or increase the glass transition temperature of SB latex polymers excessively, but these methods have not been successful. Although it is possible to improve the gloss of white paper using the above method, a major defect arises in that the pigment binding force of the binder is reduced, resulting in a picking phenomenon during the printing process. On the other hand, Special Publication No. 46-3524-IP
% Publication No. 62-29558, some of the inorganic pigments
A method has been proposed in which an aqueous dispersion of a certain percentage of pigments, so-called gelastec pigments, is placed in an aqueous dispersion, but the drawback is that the cost increases excessively if the desired gloss is not achieved In addition, since such an aqueous dispersion of the L-based material does not have a binder function, it cannot be used as a part of the 8B latex. In the end, with the technology up to now, it has not been possible to satisfy the high standards of both big strength and clean slate.

On the other hand, the printing methods for coated paper are mainly offset printing and gravure printing, and among these, in gravure printing, halftone dot reproducibility, that is, a low halftone missing rate is required as an important characteristic. This property improves as the smoothness and flexibility of the coating layer increases, so SB latex, which is extremely flexible and has a glass transition temperature of 120°C or less, is used as a binder for coated paper for gravure printing. There is.

However, due to this low glass transition temperature, the adhesiveness of the 110 body was strong, and during the super calender treatment after coating, which is a process for smoothing the surface of the coating layer, paint smeared on the calender cool, causing stains on the roll. do. This dirt, so-called no-two-pur dust, gradually accumulates, causing major defects that require the mill to shut down and clean the rolls.

One way to reduce Q is to increase the amount of lubricants such as metal soap and wax, but increasing the amount of these additives greatly impairs halftone dot reproducibility. In the end, the current state of the art is that there is no way to solve the problem of super dust without impairing halftone dot reproducibility with conventional technology, and operability is unavoidably sacrificed.

A Companion Means to Solve the Problems> The present inventors have conducted intensive studies on a paper coating binder that overcomes this situation, and as a result, have completed the present invention. That is, the present invention provides ta) styrene 3
0~69.53! Amount (1)l Acrylic acid alkyl ester with an alkyl group having 2 to 8 carbon atoms 60 to
60Jkt% (C) Ethylenically unsaturated carboxylic acid 0
．． An agricultural composite latex comprising 5 to 101 amount of component, wherein the minimum -N@ degree of the dry polymer particles is 35 to 706 C, and the gel base of the film formed from the composite latex. This is a binder for paper coating which has a t% characteristic of 0 to 401 children.

The binder of the present invention can be used in place of the conventional SB latex, but in addition to the above-mentioned Bic strength i + Shiragami Motozawa and non-adhesive properties, it also has other properties required for coated paper, such as ink transfer. Considering the overall quality balance including properties such as hardness, printing gloss, etc., the preferred method of use is to mix it with 8B latex designed for conventional uses. Note that the mixing ratio of the binder of the present invention and the SB latex may vary as desired.

The mixing ratio of the binder of the present invention and the 8B latex is usually in the range of 10:90 to 80:20 dry weight ratio, preferably 25 to 70:30 dry weight ratio.

For example, SB latex for offset printing paper contains 25 to 451 ijct% of butadiene, 52 to 7.1% of styrene, and 1 to 1.1% of enalenic unsaturated carboxylic acid.
With a monomer composition of 7x hydrogen, the glass transition temperature is 110~2
In the range of 0℃, butadiene 40-70m[%, styrene 26-59]km%,
Ethylenically unsaturated carboxylic acids having a monomer composition of 1-71% and having a glass transition ihi in the range of -20 to -60°C are most commonly used. Of course, monomers other than the basic monomer components of these SB-based latexes may be used as desired in the range of 0 to 4 oxi-s. These monomers include methacrylic acid alkyl esters, acrylic acid alkyl esters, vinyl cyanide, and various functional monomers, examples of which are listed below.

The present invention will be explained below.

Styrene as a constituent fraction of the polymer is 60~
69.5 must be included within the range of 2%, and 30
If it is less than 31 fcm, it is impossible to improve gloss, non-adhesiveness, and printability, and if it exceeds 69.53 kit%, the pink strength will be insufficient. Acrylic acid alkyl ester having an alkyl group having 2 to 8 carbon atoms needs to be included in the range of 60 to 60 mf%, and 30X! If it is less than s, the big strength is low, and if it exceeds 60', it becomes glossy, non-adhesive,
Printability becomes insufficient. Alkyl group has 2 to 8 carbon atoms
Examples of acrylic acid alkyl esters include ethyl acrylate, n-butyl acrylate, isobutyl acrylate, cyclohexyl acrylate, cyclohexyl acrylate, and 2-ethylhexyl acrylate. Among these, ethyl acrylate and n-butyl acrylate are preferably used.

It is necessary to contain 0.5 to 10Xi of ethylenically unsaturated carboxylic acid; if the diameter is less than 0.53, the dispersion stability of the latex will be insufficient, and mechanical shearing during paint preparation and coating will be insufficient. Problems such as agglomeration due to force or abnormal increase in viscosity, making uniform coating impossible, occur. If the plate thickness exceeds 10Jk, the viscosity of the paint increases, so it is necessary to lower the solid content, which causes problems such as increased drying load, decreased water resistance of the paint film, and reduced wet t-tuk strength. This causes a problem of deterioration.

As the ethylenically unsaturated carboxylic acid, acrylic acid, methacrylic acid, itaconic acid, fumaric acid, maleic acid, maleic anhydride, etc. are preferably used, and the preferable content varies depending on the type of monomer, but 1 to 7 JIL. Arrogant.

In the present invention, if desired, other ethylenically unsaturated monomers' may be added to 20:! It is possible to add up to the amount. If the amount exceeds 20 μm, it becomes impossible to achieve all the objectives of the present invention. Examples of other ethylenically unsaturated monomers include methyl methacrylate, ethyl methacrylate,
Cyanation of methacrylic acid alkyl esters such as methacrylic acid Zotel, acrylic acid alkyl esters whose alkyl group has a carbon number other than 2 to 8 such as methyl acrylate, nonyl acrylate, dodecyl acrylate, acrylonitrile, methacrylateril, etc. These include vinyls, α-methylstyrene, vinyltoluene nanoaromatic monomers, vinyl esters such as vinyl acetate, vinyl propionate, and vinyl persate, as well as functional monomers such as acrylamide, methacrylamide,
Glycidyl acrylate, methacryludalicidyl, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, N-methylolacrylamide, N-butoxymethylacrylamide, phosphooxyethyl methacrylate acid, 5-chloro-2-acid methacrylate Examples include phosphooxypropyl, methylpropanesulfonic acid acrylamide, dimethylaminoethyl methacrylate, and diethylaminoethyl methacrylate.

A mucous latex composed of the above-mentioned monomers can be produced by a conventional emulsification method. That is, in a dispersion system whose basic composition is water, a surfactant, a monomer, and a radical 1 cocatalyst, the monomer is a J&L aggregate particle dispersion.

Examples of surfactants include anionic surfactants such as fatty acid soap, alkyl sulfone t[E, dialkylaryl sulfonate, purkylsulfosuccinate, polyoxyethylene alkyl sulfate tJi, and polyoxyethylene furkylaryl sulfate. There are nonionic surfactant injection agents such as polyoxyethylene alkyl ether, polyoxyethylene alkylaryl ether, polyoxyenalene sorbitan fatty acid ester, and oxythelene oxypropylene block copolymer. In addition to these ordinary surfactants, so-called reactive surfactants, which combine a monomer group such as a vinyl group or an allyl group with a hydrophilic group such as a sulfonate group, a hydroxyl group, or a polyoxyethylene group, are used. Compounds with The surfactant is usually used alone or in combination with an anionic surfactant and a nonionic surfactant.

The amount of surfactant added is usually 0.1 to 2 with respect to the monomer.
It can be used within the range of m.

As a 1-coupling catalyst, 7X bath-based or 7' (7X bath-soluble or 7') is an oil-soluble persulfate or peroxide. , azobis compounds, such as potassium persulfate,
Sodium persulfate, ammonium persulfate, hydrogen persulfate, t-
Butyl hydroperoxide, benzoyl peroxide, 2
．． 2-Azobisisopnalonitrile, 2.2-Azobis(2-amidinopropane) hydrochloride, 2,
Examples include 2-azobis(2,4-dimethylvaleronitrile), among which water bathable ones are particularly preferred, and persulfates are most preferably used. The amount of the catalyst to be added is usually Q in the range of 1 to 1.51 relative to the monomer. In addition, if you want to accelerate the polymerization rate or achieve polymerization at a lower temperature, use sodium bisulfite, ferrous chloride, ascorbic #
! Alternatively, the so-called redox 1 method can be used in combination with a reducing agent such as its salt, erythorbic acid or seven salts, or Rongalit. Also,
Various combinations of MJtq and km may be added as desired. For example, caustic soda, potassium hydroxide, aqueous carbonate), pH adjusters such as IJum, sodium carbonate, sodium hydrogen phosphate, and sodium dihydrogen phosphate, chelating agents such as yanithylenediaminetetraacetic acid and its salts, or alkyl mercaptans. It is a chain transfer agent for adjusting the molecular weight of polymers, including carbon and tetracarbon %.

Next, as a requirement of the present invention, the minimum melting temperature of the dry polymer particles of the electropolymer latex must be in the range of 35 to 70°C. If the heating temperature is less than 35°C, it will not be possible to improve the white paper Motozawa and non-viscosity properties;
If the temperature exceeds °C, the pick strength decreases.

Furthermore, the glue fraction of the film formed from this polymer latex must be in the range of 0 to 40% by weight;
Scratching strength exceeding 0 [t% decreases.

Note that the minimum melting temperature of the dry wire coalescence and the glue fraction of the film are not determined automatically by the requirements of the constituent components of the polymer, but are determined by the various maple functional monomers and emulsifiers added as desired. It fluctuates depending on factors such as - of the gold production system. Increasing the temperature of the dry polymer to a low RIi temperature and adjusting the RL fraction of the film to a predetermined range are carried out by appropriately adjusting the amount of chain transfer agent entangled. As the chain transfer agent, alkyl mercaptans such as dodecyl mercaptan are preferably used, and the amount added is usually in the range of 0 to 1% by weight based on the monomer.

Examples and Specific Examples> The present invention will be specifically described below based on Examples and Specific Examples, but it goes without saying that the present invention is not limited only to these Examples. In addition, the parts and 俤 in the text are based on the mu lid.

(1) Preparation and properties of electrolyte latex In a reaction vessel equipped with a stirrer, reflux condenser, dripping tank, and thermometer, 611 parts of water, a power saw and 2.5 m
, / IJ oxyethylene nonyl phenyl ether (Kao Corporation, Hibi "Emuldan 920") 4 parts, sodium dialkyl sulfosuccinate 75% water 60 (Japan Cyanamid Co., Ltd., "Aerosol 0T-75J") 4s' (r) Then, 6 parts of LrM soda was added to 114 parts of water, and then the mixture of monomer and chain transfer agent shown in Example 1 was poured over a period of 4 hours. Of the monomers, only itaconic acid was mixed with a single lid?! I was charged in advance to the reaction vessel and homogenized before flowing in. After the monomer inflow t-, the temperature was 90°C. After raising the temperature to After filtering through a 200-mesh filter cloth, it was subjected to the following test.

The minimum melting degree and gel fraction of the dry polymer particles were measured by the following method. The results are listed in 1.

Minimum melting temperature of dried polymer particles: At the lowest temperature, the aluminum plate of the exchange temperature measuring device (manufactured by Takabayashi Rika Co., Ltd.) was set at 15°C on the entire surface, and after 9 days, the polymer latex' (I- Cast to a thickness of 100 microns,
Powder by drying. Next, one end of the aluminum plate was set to 20°C and the other end was set to 11-90°C to form a temperature gradient. Determine the minimum m degree at which the powder summer coalescence changes from white to transparent or translucent, and the minimum melting point Ofh
degree.

Gel fraction: The polymer latex is uniformly applied onto a polypropylene film using a /1626 wire bar and dried in a drying oven at 90°C to form a film. The latex film peeled off from the polypropylene film was weighed approximately o, sg'a on a chemical balance.
Weigh out 30 m of toluene and add it to a container containing IC.

After stirring the container with a shaker at a temperature of 3 F#f, the contents are filtered through a 200-mesh wire mesh that has been accurately weighed in advance, and the residue remaining on the wire mesh is dried and weighed.

The gel fraction is calculated using the following formula.

Film weight after immersion in toluene: Less than 3 people - Not edible (2) Performance evaluation part 1 Performance measurements were performed on the polymer latex prepared in (1). The applied paint has the composition shown in Table 2, non-volatile content concentration 62%, PH? ! - Adjusted to 9.5 with ammonia water.

Table 3 shows the conditions for preparing coated paper using this coating y#+.

Table 2 Paint formulation g (drying part) Compounding agent Mixing l For compounding 9) Grade 1 clay 1) 50.0 50.0 Grade 2 clay 2) 30
．． 0 30. ON quality calcium carbonate”) 20.U
20i0 Dispersant 4) 0.3 0.3 Slipper J 5) 0.5 0.5 Waterproofing agent 6
) 1.0 1.0 Modified starch 7) Polymer latex of batter 1 7.5 -8B latex 8) 7,5 15.0 (Note) l) "Ultra White 90" manufactured by Endelhard 2) Endelhard "Ultracoat" manufactured by Sankyo Seifun Co., Ltd. 3) "Niscallon $1500J" manufactured by Sankyo Seifun Co., Ltd. 4) "Aron T-40J" manufactured by Toa Gosoku Kagakusha 5) rDEF922J manufactured by Nissin Chemical Co. 6) "Sumireze 636" manufactured by Sumitomo Chemical Co. 7) Tamago National "Tamako Ace B" manufactured by Asahi Kasei Corporation 8) Carboxylated SB latex rL1608J manufactured by Asahi Kasei Industries, Ltd. 9) Comparison of compound n is 8B latex alone Comparative example JS Below/Table 6 Coated paper IS #I tear condition Coating machine Two bench blades Coater (manufactured by Nippon Seiki Co., Ltd.) Coating speed: 15rIL/min Dry f# Temperature: 956C Base paper Futagamisagi coated base paper (tsubo [85, V/K”) Coating it: 15N/17!2 (single side) Super Calendar Conditions Model: Pente Super Calendar Roll manufactured by Yuri Roll Kikai Co., Ltd. Temperature: 50°C Pressure: 1001c9/cIL Number of paper passes:
The physical properties of the twice-coated paper were Bic strength and white paper gloss, and 〇-tick strength, which was measured by the following method, using an RI printability tester (manufactured by Mei Seisakusho). /l640-le with tack value 26 ink (SD Susu Deluxe 50 Beni BJ manufactured by Toka Shiki Co., Ltd.) 0.4c
Make sure to turn the roll so that it is evenly coated.5
Knead for a minute, print the coated paper pasted on a mount 5 times, remove any zapping on the bim roll onto another mount, and judge the extent. The evaluation was in five stages: ◎ (excellent), ○, Δ, ×, and XX (poor) in descending order of picking.

white paper gloss Measured using Murakami GM-26Dff density meter.

People of light, set the reflection angle to 75°.

The results are shown in Table 4 above. As is clear from this, the physical properties of the coated paper using the polymer latex that satisfies the requirements of the present invention are that it has very high white paper strength while maintaining the seal strength. If you use summer okitai latex or SB type terratex alone, you can only obtain a low level of either big strength or white paper Motozawa.

Red 4 Coated paper physical properties - Part 1 Compound and latex standard Bic strength White paper gloss (%
) combination! Example Latex 1 0 35.9 Latex 2 0 69.1 Latex 6 0 66.6 Latex 4
0 70.4 Latex 5 0 66.8 Latex 6
0 72.4 Comparative Example Latex 7 Δ 56.1 Latex 8 0 51.1 Latex 9
0 54.5 Latex 1Q xx 71.3 Latex 11 ◎ 50.7 combination n SB
Latex alone ◎ 53.2 (3) Performance evaluation 2 (11 vs. The performance evaluation of the cracked polymer latex as a coated paper for gravure printing was carried out. The coating material had the composition shown in Table 5, Non-volatile content 62%.

The pH was adjusted to 9.5 with aqueous ammonia.

Table 5 Paint composition (5 parts dry) Compounding agent Mixture l Mixture n7) Grade 2 clay 1) 70.0 Grade 2 clay 2) 30,
0 30.0 Dispersant 3) 0.4 0.4 Lubricant” 1.0
1.0 modified starch 5) 1.01.0 Polymer latex of Table 1 3.0 -8B
Latex 6) 5.0 8.0 (Note) l) J,
M, “Hydrasperse” manufactured by Zuber 2) Enderhard Exhibition r Ultra Coat” 3) Toagosei Kagaku Co., Ltd. “Aron T-40J4) rDE manufactured by Nissin Kagaku Co., Ltd.
F922J 5) Shikishima Starch company “Mermaid M210J6) Carboxylated 8B latex rL1457 manufactured by Asahi Kasei Corporation
J 7) Comparative example of formulation n = 8B latex alone The preparation conditions for coated paper using this paint were as follows: Medium-quality coated paper (
The same procedure as in Table 6 was conducted except that the basis weight was 48 g/fi2)k and the coating amount was 12 g/m''.

The coated paper was evaluated for its physical properties such as bulk strength, dot defect #r ratio, and stickiness resistance. Big strength is ink t with tack value 8
The procedure was the same as described above except for the mochi. Halftone dot loss rate and stickiness resistance were measured as described in 1 below.

Missing halftone rate Uses a Ministry of Finance Printing Research Institute style gravure printing testing machine.

Printing was performed using a halftone gravure plate, the number of missing halftone dots was counted, and the results were evaluated in five stages: ◎ (excellent), ○, Δ, ×, XX (poor) in descending order of missing dots. Ta.

Coated paper is sandwiched between two mirror-polished steel plates, and 2 is coated with 9150c.
TrL2 load xyil- applied, relative humidity 80%
, and kept in an atmosphere at a temperature of 50°C for 2 hours. The plate was taken out, the coated paper was removed, and the plate was evaluated on a five-point scale from 11@ to ◎ (f), 01Δ, ×, and XX (poor), with little dirt and stickiness at the steel plate interface.

The results are shown in Box 6. As is clear from this, the physical properties of the coated paper using the Example Mu coalesced latex that satisfies the requirements r of the present invention are such that while maintaining the shock strength, the halftone dot re-dust resistance,
It had excellent stickiness resistance. On the other hand, the comparative latex and the SB yarn Silatex alone had defects in some physical properties.

Table 6 Physical properties of coated paper - Part 2 Formulation and latex composition Bic strength halftone reproducibility resistance 1 Note I Example latex 1 0 0 0 latex 2
0 ◎ ○ Latex 6 ◎ O.

Latex 4 0 0 ◎ Latex 5 0 0 0 Latex 6 0 0 0 Comparative example latex 7 Δ × Δ Latex 8 0 X ○ Latex 9 0 Δ Δ Latex 10
XXOX Latex 11 ◎ Δ Δ combination n
SB latex alone ◎ Oxygen effect> By using the binder for paper coating of the present invention, it has become possible to comprehensively improve the blankness, non-adhesiveness, and printability of coated paper.

Patent applicant Asahi Kasei Kogyo Co., Ltd. Procedural amendment (voluntary) November 27, 1985 Director General of the Patent Office Kunio Ogawa 1, Indication of case 1988 Patent Application No. 268247 2, Title of invention For paper coating Binder 3, Person making the amendment Relationship with the case: Patent applicant 1-2-6-4 Dojimahama, Kita-ku, Osaka-shi, Osaka Prefecture, "Detailed description of the invention" column 5 of the specification to be amended, Contents of the amendment +11 "Toluene 30" on page 15, line 18 of the specification
Correct "30 cc of tetrahydrofuran" to "30 cc of tetrahydrofuran."

(2) On page 16, line 4 of the same page, [Gel fraction (%) = is corrected as "Gel fraction (%) = Film weight before immersion in tetrahydrofuran x 100J].

that's all

Claims (1)

Scope of claims: (a) 30 to 69.5% by weight of styrene (b) 30 to 60% by weight of an acrylic acid alkyl ester whose alkyl group has 2 to 8 carbon atoms (c) Ethylenically unsaturated carboxylic acid 0 .5 to 10% by weight of the polymer latex, the minimum fusion temperature of the dry polymer particles is 35 to 70°C, and the gel fraction of the film formed from the polymer latex is 0~
A paper coating binder characterized by having a content of 40% by weight.