JP2000095995A - Aqueous resin composition for moistureproof coating - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an aq. resin compsn. excellent in moistureproofness, etc., by incorporating an aq. dispersion contg. a carboxylated styrene-acrylic copolymer and a polyvalent metal complex salt, a synthetic styrene-butadiene rubber latex, an ethylene-acrylic acid copolymer with a specified average mol.wt., and a low-molecular hydrocarbon resin with a specified average mol.wt. into the same. SOLUTION: This compsn. contains 65-15 wt.% (solid content basis) aq. dispersion contg. a carboxylated styrene-acrylic copolymer and a polyvalent metal complex salt, 5-25 wt.% (solid content basis) synthetic styrene-butadiene rubber latex, and 20-60 wt.% sum of an ethylene-acrylic acid copolymer which has an average mol.wt. of 10,000-30,000 and an acid value of 100-200 and a low- molecular hydrocarbon resin (e.g. polybutene) which has an average mol.wt. of 500-5,000 and is liq. at normal temp., the sum of all the above ingredients being 100 wt.%. The compsn. is excellent in resistances to wet blocking and hot blocking.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aqueous resin composition for coating paper and, more particularly, to a moisture-proof coating which imparts moisture resistance without using wax and which has excellent disintegration properties for recycling used paper. It is an aqueous resin composition.

[0002]

2. Description of the Related Art Conventionally, polyolefin laminated paper has been widely used for wrapping paper and the like that require moisture proof properties.
However, in this case, although it has excellent moisture proof properties, it is a major problem because it has no disintegration properties when reused as waste paper from the viewpoint of resource saving after use.

On the other hand, as a resin composition for coating to obtain a moisture-proof coated paper having a disintegrating property, synthetic rubber latex,
A composition in which a wax emulsion is blended with a flexible resin such as an acrylic emulsion is disclosed (JP-B-55-22597, JP-B-62-288).
No. 26, etc.). However, in this case, the same moisture-proof performance can be obtained in the initial stage as compared to a polyolefin-laminated paper coated with the same thickness. In the process of using the wax, there is a problem that the wax component on the moisture-proof surface shifts and transfers due to friction, and the moisture-proof performance is reduced, and the contact surface is contaminated with the wax. In addition, the moisture-proof surfaces are inferior in blocking resistance when they are superimposed on each other, and when used as wrapping paper, the moisture-proof surface and the back surface are bonded with a hot melt adhesive. There is a problem of lowering.

On the other hand, as a method for improving the above-mentioned problems caused by the use of wax, Japanese Patent Application Laid-Open No. 8-284,094 discloses a method in which a polyterpene resin having good compatibility with wax is used in combination with wax. In this method, although the problem of the migration of the wax component from the moisture-proof surface and the problem of the adhesiveness are improved to some extent, the moisture-proof performance is obtained by processing such as bending when the coating layer is used as wrapping paper because the coating layer becomes brittle. There is a problem that decreases.

Further, as a method for improving the bending resistance and the blocking resistance of the moisture-proof surface, a composition comprising a synthetic rubber latex, an acrylic emulsion and a wax emulsion is disclosed in Japanese Patent Application Laid-Open No. 8-1766992. As a method for exhibiting moisture resistance with a low coating amount, JP-A-6-184988 discloses a composition comprising a synthetic resin binder such as an acrylic emulsion, an aqueous varnish (water-soluble resin) and an aqueous wax emulsion. ing. However, neither of these methods can sufficiently solve the problem of wax migration described above.

[0006] Further, in order to solve the wax migration problem, a method using no wax is disclosed. Japanese Patent Application Laid-Open No. 9-67795 discloses a moisture-proof composition comprising a synthetic resin latex containing at least one of a hydrocarbon oligomer which is liquid at ordinary temperature or an organic resin having a softening point of 180 ° C. or lower, and a flat pigment. ing. But,
20-30 g / m ² · 24 at 20 g / m ² application amount
h and practical moisture permeability are obtained, but there is a strong demand for lower moisture permeability. Japanese Patent Application Laid-Open No. 9-268494 discloses a method in which a moisture-proof paper having a moisture-proof composition layer composed of a flat pigment and a synthetic resin is provided with a coating layer composed of a crosslinked body of a water-soluble resin. However, the moisture blocking resistance is insufficient, and the coating process is complicated, which is disadvantageous in economy.

[0007]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a moisture-proofing property superior to that of the conventional method for laminating a polyolefin, and particularly to an aqueous coating composition containing the above-mentioned wax emulsion. To solve the migration of wax from the moisture-proof surface and the adhesiveness of the moisture-proof surface, and to prevent a decrease in moisture-proof performance due to bending during packaging.
An object of the present invention is to provide a water-based resin composition for moisture-proof coating which is excellent in moisture blocking resistance, heat blocking property, disintegration at the time of reuse of waste paper and economical and does not use wax.

[0008]

The present inventors have conducted various studies on a method for enhancing the moisture-proof effect without using any wax which is effective in imparting moisture-proof properties. Polyethylene laminate having a moisture permeability of 40 to 25 g / m ² · 24 h by combining an ethylene / acrylic acid copolymer and a hydrocarbon-based low molecular weight resin with a metal-crosslinkable styrene / acrylic copolymer having a property It has been found that excellent moisture resistance superior to or higher than that obtained is obtained, and then various studies have been made on a composition satisfying bending resistance, moisture blocking resistance, heat blocking resistance and disaggregation during repulping. Reached. In the present invention, a combination of an ethylene / acrylic acid copolymer and a hydrocarbon-based low molecular weight resin is compatible with each other and forms a high moisture-proof layer having blocking resistance on an upper layer of an incompatible synthetic resin film. It is inferred.

That is, the present invention provides (a) an aqueous dispersion comprising a carboxyl group-containing styrene-acrylic copolymer and a polyvalent metal complex salt in an amount of 65 to 15% by weight in terms of solid content;
(B) a styrene-butadiene-based synthetic rubber latex having a solid content of 5 to 25% by weight, and (c) an average molecular weight of 1
An ethylene / acrylic acid copolymer having a molecular weight of from 000 to 30,000 and an acid value of from 100 to 200;
A hydrocarbon-based low molecular weight resin that is liquid at room temperature and has a total of (c) + (d) of 20 to 60% by weight [however, (a), (b), (c), ( The sum of d) is 1
00% by weight]. In the above (a), the carboxyl group-containing styrene-acrylic copolymer is 1 to 20% by weight of the carboxyl group-containing vinyl monomer [total of the monomer mixture is 100%.
% By weight] and (meth)
It is a copolymer containing an acrylate ester monomer as a main component, and an aqueous resin composition having a glass transition temperature of −20 to 60 ° C. is preferable.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The aqueous dispersion (a) obtained by blending a polyvalent metal complex salt with the carboxyl group-containing styrene-acrylic copolymer used in the present invention comprises a styrene monomer containing a carboxyl group-containing vinyl monomer and (meth) A copolymer having an acrylate-based monomer as a main component and having a glass transition temperature (hereinafter, referred to as Tg) of the copolymer of −20 to 60 ° C., preferably −5 to 50 ° C. This is an aqueous dispersion obtained by blending a polyvalent metal complex salt with the union. The aqueous dispersion is excellent in film formability by subjecting a copolymer having a low Tg to metal cross-linking, and gives a film having low moisture permeability, water resistance, and heat blocking properties. use. When the Tg of the copolymer is lower than −20 ° C., the coating surface has poor moisture blocking resistance and heat blocking resistance,
If the temperature exceeds ℃, the elongation of the film is reduced, and the moisture-proof property of the moisture-proof paper at the time of bending is reduced. Here, the Tg of the copolymer is determined from a calculation formula using the Tg value of each homopolymer described in “Method of indicating the film hardness of a synthetic resin emulsion (107-1996)” of the Japan Emulsion Industry Association Standard.

The carboxyl group-containing styrene-acrylic copolymer of the present invention comprises 1 to 20% by weight of a carboxyl group-containing vinyl monomer, 20 to 70% by weight of a styrene monomer,
It is obtained by copolymerizing 79 to 20% by weight of a (meth) acrylate monomer and 0 to 30% by weight of another vinyl monomer.

The amount of the above-mentioned carboxyl group-containing vinyl monomer to be used is 1 to 20% by weight, preferably 5 to 15% by weight. If the amount is less than 1% by weight, the stability of the copolymer during polymerization decreases, and the heat-resistant blocking resistance of the film also decreases. If it exceeds 20% by weight, the viscosity at the time of neutralization of the copolymer increases, and the viscosity stability over time decreases. Examples of the carboxyl group-containing monomer include (meth) acrylic acid, maleic acid, maleic anhydride, itaconic acid, crotonic acid, and maleic anhydride, itaconic anhydride and a linear or branched chain having 1 to 12 carbon atoms. And a half ester with an alcohol having the formula:

As the above (meth) acrylate monomer, various monomers can be used, and methyl (meth) acrylate
Acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, Isobonyl (meth) acrylate, benzyl (meth) acrylate and the like can be mentioned. In particular, one or two selected from esters having a straight or branched chain having 4 to 12 carbon atoms.
More than one monomer is preferred.

The other vinyl monomers mentioned above include:
α-methylstyrene, chlorostyrene, 4-hydroxystyrene, vinyltoluene, (meth) acrylonitrile, vinyl acetate, vinyl propionate, vinyl versatate and the like. A vinyl monomer having 2 to 3 double bonds such as divinylbenzene, diallyl phthalate, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, and trimethylolpropane tri (meth) acrylate;
An acid amide group such as (meth) acrylamide, N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N-methylol (meth) acrylamide or an N-substituted amide group; Containing vinyl monomer; hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, glycerol (meth) monoacrylate, polyethylene glycol mono (meth) acrylate having a polyoxyalkylene chain having an average number of added moles of 4 to 100 moles Or hydrophilic group-containing monomers such as vinyl monomers containing hydroxyl groups such as polypropylene glycol mono (meth) acrylates. An epoxy group-containing monomer such as glycidyl (meth) acrylate or 3,4-epoxycyclohexyl (meth) acrylate can also be used.

The styrene-acrylic copolymer containing a carboxyl group of the present invention can be obtained by a usual emulsion polymerization method using a radical polymerization initiator as a monomer. If necessary, a polymerization modifier, a particle diameter modifier and the like can be used. Radical polymerization initiators are those that generate radicals by heat or reducing substances to cause addition polymerization of vinyl polymerizable monomers, and are water-soluble or oil-soluble persulfates, peroxides, azobis compounds and so on.
For example, potassium persulfate, sodium persulfate, ammonium persulfate, hydrogen peroxide, t-butyl hydroperoxide, t-butyl peroxybenzoate, 2.2-
Azobisisobutyronitrile, 2.2-azobis (2-
Diaminopropane) hydrochloride, 2.2-azobis (2.4-dimethylvaleronitrile) and the like.
More preferably, they are water-soluble. The amount used is usually 0.05 to 2 parts by weight based on the monomer. In addition, if it is desired to accelerate the polymerization rate and further perform polymerization at a low temperature, a reducing agent such as sodium bisulfite, ferrous chloride, ascorbate, sodium formaldehyde sulfoxylate is combined with a radical polymerization initiator. It can also be used.

By blending a polyvalent metal complex salt with the carboxyl group-containing styrene-acrylic copolymer of the present invention, a dense, water- and heat-resistant film is formed, and heat-resistant blocking properties are improved. The polyvalent metal complex salt used in the present invention, as an aqueous solution or an aqueous dispersion thereof, has good compounding stability and is selected from divalent or higher-valent metal compounds capable of metal crosslinking with a carboxyl group in the copolymer after coating and drying. .
For example, inorganic acid salts and organic acid salts of calcium, magnesium, zinc, aluminum, zirconium, titanium and the like can be mentioned. These metal salts are preferably used as ammonium complexes of ammonia-containing metal salts. These polyvalent metal complex salts bind to the carboxyl group after the ammonium salt of the carboxyl group in the copolymer is dried and the ammonia is volatilized. Further, from the viewpoint of stability of the compounding solution, water resistance of the metal crosslinked film, toughness, etc., zinc, an ammonium complex salt of a carbonate selected from zirconium is more effective, and zirconyl ammonium carbonate,
It is particularly preferable to select from zinc ammonium carbonate, an ammonium complex salt of zinc acetate, and the like.

The amount of the polyvalent metal complex used is preferably in the range of 0.01 to 1 equivalent based on the amount of carboxyl groups in the copolymer. If less than 0.01 equivalent, the effect of improving the heat blocking resistance is low, and if it exceeds 1 equivalent,
It is not preferable because moisture resistance and water resistance are reduced.

The amount of the aqueous dispersion (a) obtained by blending the polyvalent metal complex salt with the carboxyl group-containing styrene-acrylic copolymer in the aqueous resin composition for moisture-proof coating of the present invention is determined by the weight of the solid content. It is 65 to 15% by weight in percentage. 1
If the amount is less than 5% by weight, it is difficult to obtain sufficient disintegration for recycling waste paper, and if it exceeds 65% by weight, the moisture resistance at the time of bending is undesirably reduced.

The styrene / butadiene synthetic rubber latex (b) used in the present invention is an aqueous dispersion of a copolymer obtained by emulsion polymerization of a monomer mixture containing styrene and butadiene as essential components. Functional groups,
Those obtained by copolymerizing other vinyl monomers are also included.
As this synthetic rubber latex, styrene-butadiene latex, styrene- (meth) acrylate-butadiene latex, etc., which are commercially available from various companies, can be used. The synthetic rubber latex (b) has a Tg of-
Those having a high gel fraction of 15 to 40 ° C. and a gel fraction of about 60 to 90% are preferred.

The amount of the synthetic rubber latex used in the aqueous resin composition for moisture-proof coating of the present invention is 5 to 25% by weight in terms of weight percentage of solid content. If the amount of the synthetic rubber latex exceeds 25% by weight, it is difficult to improve the defibration property, moisture blocking resistance and heat blocking property. On the other hand, if the content is less than 5% by weight, it is difficult to prevent the moisture-proof property from being lowered by bending.

The aqueous resin composition for moisture-proof coating of the present invention needs to use the ethylene / acrylic acid copolymer (c) and the hydrocarbon-based low molecular weight resin (d) in combination. The combination of both components has a remarkable effect in further improving the moisture permeability and bendability of the polymer latex. The amounts of the ethylene / acrylic acid copolymer (c) and the hydrocarbon-based low molecular weight resin (d) occupying 20 to 60% by weight of (c) + (d) in the aqueous resin composition for moisture-proof coating of the present invention are as follows. is there.
If (c) + (d) is less than 20% by weight, the effect of improving the moisture resistance is not sufficient. If (c) + (d) exceeds 60% by weight, the disintegration property is reduced. Further, the preferable ratio of (c) and (d) is (c) / (d) = 5/1 to 1 /
5

The average molecular weight used in the present invention is 10,000.
The ethylene / acrylic acid copolymer (c) having 0 to 30,000 and an acid value of 100 to 200 has an average molecular weight of 10,
When the molecular weight is smaller than 000, the heat-resistant blocking property is reduced in combination with a hydrocarbon-based low molecular weight resin. If it exceeds 30,000, the effect of improving the moisture permeability by using it in combination with a hydrocarbon-based low molecular weight resin is not sufficient. The average molecular weight is indicated by a weight average molecular weight. If the acid value is less than 100, dispersibility in water will be poor. If the acid value exceeds 200, the solubility in water increases, so that the viscosity of the aqueous dispersion increases, and the viscosity of the coating liquid increases, making it impossible to perform uniform coating. Preferred ethylene / acrylic acid copolymers have a copolymerization ratio of acrylic acid of 1
It is a copolymer consisting of 5 to 20% and having a Bica-softening point of 40 to 60 ° C. The ethylene / acrylic acid copolymer can be used as an aqueous dispersion by a method of suspending in water and melting under heating in the presence of an alkali. As the alkali used for dispersing in water, ammonia water,
There are inorganic bases of alkali metal hydroxides and organic bases such as organic amines. Specifically, aqueous ammonia, sodium hydroxide, potassium hydroxide, monoethanolamine, diethanolamine, triethanolamine, morpholine, and the like can be used, and ammonia water is preferable.

The average molecular weight used in the present invention is 500 to
Examples of the hydrocarbon-based low molecular weight resin (d) which is liquid at 5,000 at room temperature include liquid polybutadiene, liquid SBR, polybutene, liquid polyisobutylene, and liquid butyl rubber. Among these, polybutene, which is mainly a copolymer of isobutylene and a part of n-butene in a butane-butene fraction generated by naphtha decomposition, is preferable. The average molecular weight is indicated by a number average molecular weight. If the average molecular weight is less than 500, the blocking resistance will decrease. When the average molecular weight is more than 5,000, the fluidity is reduced, and when used in combination with the ethylene / acrylic acid copolymer, the compatibility is reduced, and the moisture-proof effect is not sufficient.

The method for adding the hydrocarbon-based low molecular weight resin may be either a method in which the hydrocarbon-based low molecular weight resin is dissolved in a solvent and mixed with the above aqueous dispersion, or an aqueous dispersion obtained by a known emulsification method. can do. The use of an aqueous dispersion is preferable from the viewpoint of environmental hygiene since it has good miscibility and does not contain a solvent.

Known inorganic pigments can be used in the aqueous resin composition for moisture-proof coating of the present invention. The use of an inorganic pigment can further improve the moisture-proof property and the blocking property, and is preferable from the viewpoint of economy. Examples of the inorganic pigment include calcium carbonate, titanium oxide, talc, kaolin, zinc oxide, aluminum hydroxide, magnesium carbonate, and the like, and one or more selected from these groups can be used. The mixing ratio of the aqueous resin composition for moisture-proof coating of the present invention and the inorganic pigment is such that the inorganic pigment is 5 parts by weight per 100 parts by weight of the aqueous resin composition for moisture-proof coating.
0 to 200 parts by weight.

The aqueous resin composition for moisture-proof coating of the present invention may further comprise, if necessary, a film-forming aid, a plasticizer, a viscosity modifier, a thickener, a defoamer, a preservative, a dispersant, an antifreeze. Agents and the like can be used by blending them within a range that does not impair the effects of the present invention.

The water-based resin composition for moisture-proof coating of the present invention has practical performances such as moisture-proof properties (in planographic and bending), moisture-proof blocking properties, heat-resistant blocking properties, and adhesiveness with a water-based adhesive, as well as a re-pulping property. Excellent disintegration,
Liner for moisture-proof coated paper, especially kraft paper, corrugated ball
It is useful as a moisture-proofing agent for packaging paper such as paper and coated paper.

[0028]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples. In addition,
Parts in Examples show parts by weight, and percentage (%) shows% by weight.

Production Example A-1 (Production of an aqueous dispersion prepared by mixing a polyvalent metal complex salt with a styrene-acrylic copolymer containing a carboxyl group) 62 parts of styrene and 2-ethylhexyl acrylate were added to a beaker in advance. Take 26.5 parts, 11.5 parts of methacrylic acid, 2 parts of sodium dodecylbenzenesulfonate and 54.9 parts of deionized water, stir and emulsify. 33.6 parts of deionized water was charged into a reactor equipped with a stirrer, a reflux condenser, a thermometer, a nitrogen inlet tube, and a dropping funnel, the temperature was raised to an internal temperature of 60 ° C., and the emulsion was adjusted to a beaker in advance. 7.8 parts and 2 parts of ammonium persulfate dissolved in 10% with deionized water are charged, the temperature is raised to 80 ° C. and kept at that temperature for 30 minutes. The remaining amount of the emulsified material previously adjusted to beaker is added dropwise over 4 hours, and at the same time, 3 parts of ammonium persulfate dissolved in deionized water are added dropwise. Emulsion polymerization is performed at an internal temperature of 78 to 81 ° C. After completion of the dropwise addition, the mixture was aged at the same temperature for 3 hours, cooled to room temperature, and 9.3 parts of an aqueous solution of zinc ammonium carbonate separately prepared as described below (0.1 part based on the carboxyl group of the polymer).
25 equivalents) and 1.39 parts of 25% aqueous ammonia. Solid content 50%, pH 8.3, viscosity 130c
p, aqueous dispersion A of a polyvalent metal complex salt of a styrene-acrylic copolymer containing a carboxyl group having a Tg of 37.5 ° C.
1 was obtained.

Production Examples A-2 to A-7 (Production of Aqueous Dispersions in which Polyvalent Metal Complex Salt is Mixed with Carboxyl Group-Containing Styrene / Acrylic Copolymer) The aqueous dispersions of Production Examples A-2 to A-7 are: A carboxyl group-containing styrene-acrylic copolymer obtained in the same manner as in Production Example A-1 except that the type and amount of the monomer and the amount of the zinc ammonium carbonate aqueous solution added were changed as shown in Table 1 below. An aqueous dispersion containing a polyvalent metal complex salt.

Production Example A-8 (Production of Aqueous Dispersion of Carboxyl Group-Containing Styrene-Acrylic Copolymer) The aqueous dispersion of Production Example A-8 was prepared by adding no aqueous solution of zinc ammonium carbonate as shown in Table 1 below. Is a carboxyl group-containing styrene / acrylic copolymer aqueous dispersion obtained in exactly the same manner as in Production Example A-1.

[0032]

[Table 1]

In the table, the types of monomers are indicated by the following abbreviations,
As the calculated Tg of the copolymer, the Tg of each single polymer shown in parentheses was used. St: styrene (Tg: 100 ° C) MMA: methyl methacrylate (Tg: 105 ° C) BA: butyl acrylate (Tg: -52 ° C) 2EHA: 2-ethylhexyl acrylate (Tg:
-70 ° C) AAc: acrylic acid (Tg: 106 ° C) mAAc: methacrylic acid (Tg: 185 ° C)

Production Example B-1 (Preparation of aqueous dispersion of ethylene / acrylic acid copolymer) In a dissolution apparatus equipped with a stirrer, a reflux condenser and a thermometer, 222 parts of deionized water, ethylene / acrylic acid copolymer ( Dow·
100 parts of Primacol 5980 manufactured by Chemical Co., Ltd., acrylic acid 20%, softening point of 50 ° C.) and 11.5 parts of aqueous ammonia (25%) were charged, and the internal temperature was 85-9.
Raise to 0 ° C. and disperse for 4 hours. Cool to room temperature after dispersion, solid content 30.0%, pH 9.0, viscosity 5,500c
An aqueous dispersion of p was obtained.

Preparation of Aqueous Zinc Ammonium Carbonate Solution A reaction vessel equipped with a stirrer was charged with 65 parts of deionized water, 35 parts of zinc oxide, and 35 parts of ammonium bicarbonate.
83.5 parts of 5% aqueous ammonia was added and reacted. The resulting ammonium aqueous solution of zinc ammonium carbonate is
The concentration was 16% in terms of zinc oxide.

Example-1 86 parts (solid content ratio: 43%) of the aqueous dispersion A-1 obtained in Production Example A-1 was mixed with a styrene / butadiene synthetic rubber latex (SBR rubber manufactured by Asahi Kasei Kogyo Co., Ltd.). Latex DL-612: butadiene content 40-55
%, Solid content 48%, pH 10.5, film formation temperature 2 ° C)
9.2 parts (14%), 96.7 parts (29%) of the ethylene / acrylic acid copolymer aqueous dispersion obtained in Production Example B-1,
Hydrocarbon low molecular weight resin (Nippon Petrochemical Co., Ltd. H
E-1975 (solid content 75%) 18.7 parts (14%)
After adjusting the solid concentration, pH and viscosity by stirring and mixing, the solid
An aqueous resin composition for moisture-proof coating of the present invention having a pH of 7%, a pH of 8.5 and a viscosity of 700 cp was obtained. This moisture-proof coating aqueous resin composition was applied to both bleached kraft papers (70 g / m ² ) at a rate of 20 g / m ² · dry and immediately dried at 130 ° C. for 1 minute to obtain a moisture-proof coated paper. Moisture-proof core obtained as above
As shown in Table 2, the paper has moisture permeability, moisture blocking resistance,
Both heat blocking property and adhesiveness were extremely good. In addition, the disintegration was evaluated using a standard pulp disintegrator. Therefore, it proves that it is practical for reuse of waste paper.

Examples 2 and 3 The aqueous dispersion A-1 of Example 1 was the same as the aqueous dispersion A-1.
This is an example in which the mixing ratio of SBR rubber latex, (c) ethylene / acrylic acid copolymer, and (d) hydrocarbon-based low molecular weight resin was changed, and both used inorganic pigments. Example-
No. 2 used talc (SP-38, average particle size of 20 to 22 μm, manufactured by Fuji Talc Industries Co., Ltd.) as an inorganic pigment, and Example-3 used calcium carbonate (heavy calcium carbonate R, manufactured by Maruo Calcium Co., Ltd.) as an inorganic pigment. Using an average particle diameter of 13 μm), a moisture-proof paper was produced in exactly the same manner as in Example-1. As shown in Table 2, the obtained moisture-proof paper was excellent in moisture permeability, moisture-blocking property, heat-blocking property, defibration property and adhesiveness.

Examples 4 and 5 The aqueous dispersion A-1 of Example 2 was replaced with A-2 and A-3.
(B) SBR rubber latex, except (c)
The blending ratios of the ethylene / acrylic acid copolymer and (d) the hydrocarbon-based low molecular weight resin are exactly the same as in Example-2. Example-4 uses talc as an inorganic pigment,
In Example-5, moisture-proof paper was produced in exactly the same manner as in Example-1, using calcium carbonate as the inorganic pigment. As shown in Table 2, the obtained moisture-proof paper was excellent in moisture permeability, moisture-blocking property, heat-blocking property, defibration property and adhesiveness.

Examples -6 to 9 Example -6 is an example in which (a) aqueous dispersion A-4 was used and talc was blended as an inorganic pigment, and Example -7 was (a) aqueous dispersion A-5. And Example -8 in which (a) aqueous dispersion A-6 was used and calcium carbonate was added as an inorganic pigment, Example-
9 is an example in which (a) the aqueous dispersion A-7 was used and talc was blended as an inorganic pigment. Table 2 is an example in which the mixing ratio of (b) SBR rubber latex, (c) ethylene / acrylic acid copolymer, and (d) hydrocarbon-based low molecular weight resin was changed as shown in Table 2. A moisture-proof paper was produced in exactly the same manner as in Example-1. As shown in Table 2, the obtained moisture-proof paper was excellent in moisture permeability, moisture-blocking property, heat-blocking property, defibration property and adhesiveness.

Comparative Example-1 Comparative Example-1 comprises (a) a carboxyl group-containing styrene / acrylic copolymer A-8, (b) an SBR rubber latex,
(C) An ethylene / acrylic acid copolymer and (d) a hydrocarbon-based low molecular weight resin are used, and the blending ratio is the same as in Example-1. Coating and drying were performed under the same conditions as in Example 1 to produce a moisture-proof paper. The moisture-proof paper thus obtained had a slightly poor moisture permeability, and the disintegration and adhesion were good as shown in Table 3. However, the moisture blocking resistance and the heat blocking resistance were inferior.

Comparative Example 2 Comparative Example 2 comprises (a) aqueous dispersion A-1 and (b) SBR
The rubber latex and (c) ethylene / acrylic acid copolymer were coated and dried under the same conditions as in Example 1 to prepare a moisture-proof paper. As shown in Table 3, the obtained moisture-proof paper had good moisture blocking properties, heat blocking properties, defibration properties and adhesive properties. However, the moisture permeability was inferior.

Comparative Example 3 Comparative Example 3 comprises (a) aqueous dispersion A-1, (b) SBR
The three components of rubber latex and (d) hydrocarbon-based low molecular weight resin were applied and dried under the same conditions as in Example 1 to produce a moisture-proof paper. The disintegration and adhesiveness of the obtained moisture-proof paper were good as shown in Table 3. However, the fold test for moisture permeability, the moisture blocking resistance and the heat blocking resistance were inferior.

Comparative Example 4 Comparative Example 4 comprises (a) aqueous dispersion A-1, (b) SBR
Two components of rubber latex were applied and dried under the same conditions as in Example 1 to produce a moisture-proof paper. As shown in Table 3, the obtained moisture-proof paper had good moisture blocking properties, heat blocking properties, defibration properties and adhesive properties. However, the moisture permeability was very poor.

Comparative Example-5 Comparative Example-5 comprises (a) aqueous dispersion A-1, (b) SBR
Comparative example in which rubber latex, (c) ethylene / acrylic acid copolymer, (d) hydrocarbon-based low molecular weight resin and talc were blended in the proportions shown in Table 3 and were the same as in Example-1. The coating was dried under the following conditions to prepare a moisture-proof paper. The moisture permeability of the obtained moisture-proof paper was slightly poor, and the adhesiveness was as shown in Table 3.
As shown in FIG. However, the moisture blocking resistance, heat blocking resistance, and defibration properties were inferior.

Subject Examples Each test was similarly carried out on a commercially available polyethylene laminated paper obtained by laminating 18 μm of polyethylene. The water vapor transmission rate was 35 g / m ² · 24 h, and although the moisture blocking resistance and the heat blocking resistance were good, the disintegration was confirmed to be insufficient due to clumping of polyethylene and fibers. Also, the adhesiveness was poor.

[0046]

[Table 2]

[0047]

[Table 3]

In the table, the aqueous dispersion (a) is shown as an abbreviation for an aqueous dispersion obtained by mixing a polyvalent metal complex salt with a styrene-acrylic copolymer containing a carboxyl group.

[Test Method] A sample of the moisture-proof paper used in each test was applied to both bleached kraft papers (70 g / m ² ) with a bar coater so as to have a dry weight of 20 g / m ^2. For 1 minute.

The moisture permeability was measured at a temperature and humidity of 40 ° C. and a relative humidity of 90% according to JIS Z 0208, a moisture permeability test method (cup method) for a moisture-proof packaging material. In the fold test, the cross was creased through a press roll, and the moisture permeability of the cross portion was measured.

In the moisture blocking test, the moisture-proof coated surface of the kraft paper and the uncoated surface, and the coated surface and the coated surface of the kraft paper were respectively superposed on each other, and the load was 500 g / cm ² ··· in an atmosphere of 50 ° C. and 90% RH. The degree of blocking of the superposed surface after standing for 24 hours was determined. ◎: Peeled off without resistance ○: A little resistance when peeled off △: There is resistance when peeled, but no destruction of coating surface ×: Blocking, destruction of coating surface

In the heat blocking test, the moisture-proof coated surface and the non-coated surface of the kraft paper were overlapped with a sample width of 50 mm, and pressed with a heat sealer at 50 ° C. for 5 seconds (3 kg / c).
m ² pressure) to determine the degree of blocking. ◎: Peeling off without resistance ○: A little resistance when peeling off Δ: There is resistance but no destruction of coating surface when peeling off: Blocking and destruction of coating surface occur.

In the disintegration test, 60 g of coated paper was finely chopped and immersed in 1500 ml of water, and was stirred and dispersed for 15 minutes at 3000 rpm using a standard pulp disintegrator. It was diluted by a factor of two and the dispersion was observed. ：: There is no flocculation of undisintegrated fiber ○: There is some floc of undisintegrated fiber △: There is a little floc of undisintegrated fiber ×: There are many flocs of undisintegrated fiber

The adhesion test was conducted using an aqueous adhesive. The aqueous adhesive is a vinyl acetate emulsion, Cyvinol DB-153 (manufactured by Seiden Chemical Co., Ltd., solid content 52%, viscosity 12,000 cp, pH 4.5), and the adhesive is applied to the coating surface. Apply to 30μ (wet), immediately bond the non-coated surface, 1,000g
After applying a static load for 1 minute, the film is left in an atmosphere of 20 ° C. and 65% RH for 24 hours, and peeled off at that temperature to observe the adhesion state. ：: Broken paper ○: Broken paper 80 to 60% △: Broken paper 40 to 20% ×: Poor adhesion

[0055]

The resin composition of the present invention is excellent as a moisture-proof coating agent for wrapping paper in place of polyethylene laminated paper, and has excellent moisture-proof properties. Moisture-proof coating resin that does not contain wax that prevents moisture-proof deterioration due to bending during packaging, and that excels in moisture-blocking properties, heat-blocking properties, disintegration properties when recycling waste paper, and adhesiveness of the moisture-proof surface with an aqueous adhesive. A composition. Accordingly, the packaging object is protected from humidity as packaging paper for paper products and the like, and the used packaging paper can be handled as used paper collection paper like general paper.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4J038 CA022 CA042 CB062 CC021 CC042 CG031 GA06 MA08 MA10 MA13 MA14 NA02 4L055 AG10 AG11 AG26 AG58 AG59 AG61 AG63 AG71 AG76 AG89 AG97 AH02 AH23 AH48 AJ04 BE08 EA20 EA30 EA30 EA30 EA30

Claims (2)

[Claims] 1. An aqueous dispersion obtained by blending a polyvalent metal complex salt with a (a) carboxyl group-containing styrene / acrylic copolymer in a solid content of 65 to 15% by weight, and (b) a styrene / butadiene synthetic rubber. 5 to 25% by weight of the latex in solid content, and (c) an average molecular weight of 10,000 to 30,0
(C) an ethylene / acrylic acid copolymer having an acid value of 100 to 200 and (d) a hydrocarbon-based low molecular weight resin having an average molecular weight of 500 to 5,000 and being liquid at room temperature;
+ (D) is 20 to 60% by weight [(a),
Let the total of (b), (c) and (d) be 100% by weight]
An aqueous resin composition for moisture-proof coating comprising: 2. A carboxyl group-containing styrene-acrylic copolymer is a carboxyl group-containing vinyl monomer 1 to 2.
20% by weight (total of the monomer mixture is 100% by weight) and a copolymer mainly composed of a styrene monomer and a (meth) acrylate monomer. The aqueous resin composition according to claim 1, wherein the glass transition temperature of the aqueous resin composition is from -20 to 60C.