JPH09104798A - Thermally expansible coating composition for wall decoration and wall paper having uneven pattern - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a durable, aesthetic and economical wall decoration coating compsn. free from harmful gas evolution and excellent in flame retardancy by blending a specific acrylic copolymer emulsion with an inorg. filler and a thermally expansible hollow microspheres. SOLUTION: This thermally expansible coating compsn. for wall decoration comprises 100 pts.wt. (in terms of solid) water-based acrylic copolymer emulsion having a Tg of -45 to -15 deg.C and a gel content of at least 70wt.% [e.g. one obtd. by emulsion polymn. of a monomer mixture comprising 99-55wt.% acrylic ester monomer with a 2-9C alkyl, 0.5-6wt.% monomer capable of cross-linkage formation during polymn. 0.5-6wt.% carboxyl group-contg. unsatd. monomer and 0-44wt.% other polymerizable unsatd. monomer], 200-550 pts.wt. inorg. filler, and 5-40 pts.wt. thermally expansible hollow microspheres. This compsn. is free from harmful gas evolution, durable, aesthetic and economical, and has an excellent flame retardancy comparable to that of conventional vinyl chloride wall paper.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-expandable coating composition, and more particularly to a wall decoration using an acrylic copolymer aqueous emulsion as a binder, an inorganic filler and heat-expandable microspheres. It relates to a thermally expandable coating composition suitable for producing wallpaper.

[0002]

2. Description of the Related Art Conventionally, a so-called vinyl chloride wallpaper in which a vinyl chloride resin is formed on a paper substrate has been widely used as this type of wallpaper. However, wallpaper using a polymer containing vinyl chloride has a disadvantage in safety and environmental protection because it emits harmful chlorine gas at the time of fire or incineration.

On the other hand, a coating composition using an acrylic resin, an ethylene-vinyl acetate-based resin, a vinyl acetate-acrylic resin, a urethane-based resin as a binder, and a wallpaper using these resins as a binder are disclosed in JP-A-53. -597
28, JP-A-53-86817, JP-A-3
No. 251452, JP-A-6-33380,
JP-A-6-33399, JP-A-7-179788
Japanese Patent Laid-Open No. 7-188502 and the like. Further, a flame-retardant wallpaper having an uneven pattern formed on the surface thereof, which uses an inorganic filler together with the above resin binder and a heat-expandable microsphere as a coating composition, is known.

Particularly, in JP-A-7-179788, a glass transition temperature of −20 ° C. to 60 ° C. and 20,
A foamable aqueous coating composition is disclosed which comprises a copolymer latex having a weight average molecular weight of 000 to 500,000 and expandable particles containing a liquid blowing agent contained within a thermoplastic shell. The aqueous coating composition comprises, as solids, 30 to 90 parts by weight of latex particles, about 1 to about 8 parts by weight of expandable particles, about 2 to about 30 parts by weight of inorganic pigment, and further about 0.001 to about 0.001 of rheology improver. It consists of 2 parts by weight.

However, the wallpaper produced by these methods has a drawback that it is inferior in flame resistance and cold resistance as compared with conventional vinyl chloride wallpaper.

[0006]

In view of the present situation, for wallpaper, which does not generate harmful gas and has excellent flame retardancy comparable to that of conventional vinyl chloride wallpaper, durability, designability, and economy. Aiming to provide a coating composition, by adding a large amount of inorganic filler, which has not been attempted hitherto, to an acrylic aqueous emulsion satisfying specific conditions, particularly aluminum hydroxide, when using expandable particles The inventors have found that it is possible to produce a highly economical wallpaper having excellent bubble stabilization, flame retardancy, scratch resistance on the surface, bending resistance at low temperatures, and blocking resistance, and arrived at the present invention.

[0007]

The heat-expandable coating composition of the present invention is dispersed in an aqueous medium with an aqueous resin binder made of an acrylic copolymer which is extremely flexible and has an excellent binding force to an inorganic filler. Containing inorganic fillers and thermally expandable hollow microspheres. That is, the present invention is based on 100 parts by weight of an acrylic copolymer aqueous emulsion having a glass transition temperature of −45 ° C. to −15 ° C. and a gel fraction of 70% by weight or more (as solid content) and aluminum hydroxide as main components. A heat-expandable coating composition for wall decoration, which comprises 200 to 550 parts by weight of an inorganic filler and 5 to 40 parts by weight of heat-expandable hollow microspheres.

The glass transition temperature of the acrylic copolymer of the present invention is -45 ° C to -15 ° C, preferably -40 ° C to
-20 ° C. If the glass transition temperature is too low, the wallpaper product will have poor blocking resistance and scratch resistance on the surface,
On the other hand, when the temperature is too high, the binding force between the inorganic filler and the heat-expandable particles is insufficient, so that the scratch resistance is lowered and the flex resistance at low temperature is lowered. The glass transition temperature of the copolymer can be measured, for example, by a differential scanning calorimeter. Also, the reciprocal of the glass transition temperature (Tg) of a particular copolymer composition is usually according to Equation 1:
Each monomer, M1, M, from which the copolymer is formed
It can be estimated by calculating the sum of the respective quotients obtained by dividing the weight fraction of 2, ..., Mi by the Tg (K: Kelvin) value of the homopolymer derived from each monomer. it can.

[0009]

(Equation 1)

The gel fraction of the acrylic copolymer of the present invention is 70% by weight or more, preferably 95 to 75% by weight. When it is 70% by weight or less, the temperature dependence of the wallpaper product becomes large, the blocking resistance and the low temperature bending resistance are lowered, and the water resistance, the solvent resistance and the friction resistance are lowered. The gel fraction is measured by extracting 1 g of the copolymer film with 100 cc of ethyl acetate at 70 ° C. for 1 hour and then filtering with a 300-mesh wire net to measure the amount of insoluble matter recovered. .

A preferred embodiment of the acrylic copolymer of the present invention is 99 to 55% by weight of an acrylic acid ester monomer having an alkyl group having 2 to 9 carbon atoms and a monomer which forms a crosslink during the polymerization. 0.5 to 6% by weight of the polymer, 0.5 to 6% by weight of a carboxyl group-containing unsaturated monomer, and 0 to 44% by weight of another polymerizable unsaturated monomer, and the glass transition of the copolymer. It is a copolymer emulsion obtained by emulsion-copolymerizing a monomer mixture which can have a temperature of −45 ° C. to −15 ° C., preferably −40 ° C. to −20 ° C.

Examples of the acrylate ester monomer having an alkyl group having 2 to 9 carbon atoms include ethyl acrylate, butyl acrylate, isobutyl acrylate, hexyl acrylate, octyl acrylate, and acrylic acid-2.
-Ethylhexyl, nonyl acrylate and the like can be mentioned. 99 to 55% by weight, preferably 95 to 60% by weight of one or more monomers selected from these
Used. When it is 55% by weight or less, the binding force of the inorganic filler in the coating composition of the present invention is lowered, and the abrasion resistance of the wallpaper product is deteriorated.

As the unsaturated monomer which forms a crosslink during polymerization, a monomer having two or more radically polymerizable double bonds in one molecule, or a crosslink between polymers during the polymerization reaction is formed. Is selected from radically polymerizable monomers having a reactive group to Examples of the monomer having two or more radically polymerizable double bonds in one molecule include divinylbenzene, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate. Etc. Further, as the monomer having a reactive group that forms crosslinks between polymers during the polymerization reaction, a monomer having a reactive group that reacts with a carboxyl group-containing unsaturated monomer described below at a temperature during polymerization Examples thereof include monomers having a reactive group such as an isocyanate group, an N-alkylol-substituted amide group, a glycidyl group and an alkoxysilyl group. Examples of these monomers include (meth) acryloyl isocyanate, 2
-Isocyanate ethyl methacrylate, m- and / or p-isopropenyl-α, α'-dimethylbenzyl isocyanate, N-methylol (meth) acrylate,
Examples thereof include glycidyl (meth) acrylate, (meth) acryloxypropyltrimethoxysilane, and tetramethoxysilylpropyl (meth) acrylate. One or more selected from these monomers are used. The ratio of these monomers to be copolymerized is the amount necessary for the gel fraction of the obtained copolymer to be 70% or more, and is 0.
5 to 6% by weight, preferably 1.0 to 5% by weight are used.
If it is 0.5% by weight or less, the gel fraction is low and the gel crosslink density is low, so that the blocking resistance of the wallpaper product is lowered, and if it is 6% by weight or more, the gel crosslink density is high. Since it is too much, the binding force of the inorganic filler and the heat-expandable hollow microspheres becomes weak, and the scratch resistance of the surface becomes poor.

The carboxyl group-containing vinyl monomer is selected from acrylic acid, methacrylic acid, maleic acid, maleic anhydride, itaconic acid, itaconic anhydride and the like.
One kind or two or more kinds can be used, and the amount of the monomer to be copolymerized is 0.5 to 6% by weight, and preferably two or more radically polymerizable monomers in one molecule as the above-mentioned crosslinking forming monomer. It is 1 to 4% by weight when a monomer having a heavy bond is used, and 2 to 6% by weight when a monomer having a crosslinking reactivity with a carboxyl group is used. When it is 0.5% by weight or less, the dispersion stability when an inorganic filler is mixed is poor, and when it is 6% by weight or more, the water resistance and alkali resistance of the product are poor.

The other polymerizable unsaturated monomer is selected from monomers having radical polymerizability and copolymerizable with an acrylate ester having an alkyl group having 2 to 9 carbon atoms. Specifically, aromatic vinyl monomers such as styrene, vinyltoluene, and α-methylstyrene: methyl (meth)
Acrylate, ethyl methacrylate, butyl methacrylate, isobutyl methacrylate, lauryl (meth)
(Meth) acrylic acid esters such as acrylate, stearyl (meth) acrylate, cyclohexyl (meth) acrylate, benzyl (meth) acrylate: and (meth) acrylonitrile, vinyl acetate, vinyl propionate, vinyl ethyl ether, vinyl butyl ether, butadiene , (Meth) acrylamide, 2-hydroxyethyl (meth) acrylate, 2-hydroxyxypropyl (meth) acrylate and the like, or a mixture of two or more thereof. The proportion of these monomers to be copolymerized is 0 to 44% by weight, preferably 2 to 40% by weight.

The emulsion polymerization from the above-mentioned monomer mixture is carried out by a usual method of emulsion-polymerizing the monomer mixture in the presence of at least water, an emulsifier and a polymerization initiator. The emulsifier used in the present invention is not particularly limited and is selected from the emulsifiers used in ordinary emulsion polymerization, for example, anionic emulsifiers, nonionic emulsifiers, reactive emulsifiers, polymeric dispersion stabilizers and the like. Used alone or in combination of two or more.
Furthermore, nitrogen substitution in the polymerization reaction increases the polymerization rate,
It is effective for improving the polymerization rate, and if necessary, a polymerization degree adjusting agent, a particle size adjusting agent and the like can be used.

The copolymers of the present invention are in the form of copolymer latex particles and contain from about 30 to 65 weight percent polymer solids, preferably from about 40 to 60 weight percent. Further, the copolymer particles have a particle size of about 100 nanometer (nm) to about 500.
It has an average particle size of (nm).

The inorganic filler used in the coating composition of the present invention contains aluminum hydroxide as a main component, and other inorganic fillers may be used in combination. Other inorganic fillers include barium hydroxide, magnesium hydroxide, magnesium carbonate, calcium carbonate, calcium sulfate, barium sulfate, basic zinc carbonate, basic lead carbonate, silica sand,
Examples thereof include clay, talc, silica compounds, titanium dioxide, antimony trioxide and the like. These inorganic fillers are used in an amount of 200 to 550 parts by weight per 100 parts by weight (solid content conversion) of the acrylic copolymer aqueous emulsion of the present invention. A preferred embodiment is aluminum hydroxide 200.
-400 parts by weight, more preferably 250 parts by weight-40
0 to 150 parts by weight and one or more kinds selected from other inorganic fillers are used. In a preferred embodiment, the coating composition of the present invention is rendered flame retardant. Here, flame retardance means that in the atmosphere, the burner flame does not burn by applying 5 seconds, or the coating that ignites by applying 10 seconds extinguishes the flame within 5 seconds when the flame is removed, and combustion does not spread. Say. If the proportion of aluminum hydroxide is 200 parts by weight or less, the flame retardance is not sufficient, and if the total amount of the inorganic filler is 550 parts by weight or more, the wallpaper product is inferior in flex resistance and scratch resistance.

The heat-expandable hollow microspheres used in the heat-expandable coating composition of the present invention is a foaming agent composed of microspheres which can be expanded and foamed by heating, and examples thereof include polyvinylidene chloride, vinylidene chloride and acrylonitrile. Particle size of low-boiling point hydrocarbon solvents such as butane, isobutane, pentane, hexane, and heptane, which are microencapsulated in the shell of the copolymer, polyacrylonitrile, acrylonitrile and acrylic ester copolymer, etc. It is a sphere of ~ 50μ. As such a heat-expandable microsphere, a commercially available product (for example, trade name "EXPANCEL" manufactured by Nippon Philite Co., Ltd.) can be used. The heat-expandable microspheres are contained in an amount of 5 to 40 per 100 parts by weight (in terms of solid content) of the acrylic copolymer aqueous emulsion of the present invention.
Parts by weight Preferably 5 to 30 parts by weight are used. If it is 5 parts by weight or less, the unevenness of the wallpaper product is poor, and the design and blocking resistance are poor, and if it is 40 parts by weight or more, the surface abrasion resistance and strength are poor.

In the coating composition of the present invention, a known foaming agent can be used in combination with the above heat-expandable microspheres. Examples of the typical blowing agent include azodicarbonamide, azobisisobutyronitrile, N, N'-dinitrosopentamethylenetetramine, p-toluenesulfonylhydrazine, p, p'-oxybis (benzenesulfohydrazide). And so on.

The coating composition of the present invention may contain a thickening agent for adjusting the viscosity suitable for coating. As the thickener, commercially available thickeners such as polyvinyl alcohol, hydroxycellulose, carboxymethyl cellulose, sodium polyacrylate and the like can be used.

Furthermore, in the coating composition, 5 parts by weight or less of an external cross-linking agent may be used per 100 parts by weight (as solid content) of the acrylic copolymer aqueous emulsion. The preferred external cross-linking agent is a cross-linking agent having a polyfunctional reactive group that reacts with a carboxyl group of an acrylic polymer, for example, a methylolated melamine resin,
Examples thereof include urea-formaldehyde resin, polyfunctional isocyanate compound, epoxy resin and the like.

Furthermore, the coating composition is, for example, an antifoaming agent,
Additives known in the art such as a hygroscopic agent, a dispersant, a fungicide, a colorant, a whitening agent, an ultraviolet absorber and an anti-aging agent can be used.

To produce a wallpaper using the coating composition of the present invention, for example, the composition is coated by a roll coater, a reverse roll coater, a doctor coater, or by screen printing, gravure printing, flexo printing, or the like. The printing method may be applied to the wallpaper base material, or printed and dried and foamed. Further, a pattern can be applied by passing through an embossing roll, if necessary. In addition, the coating composition of the present invention is pattern-printed on a substrate and heated.
By foaming, a decorative concavo-convex pattern can be formed and used for purposes other than wallpaper.

The drying and foaming conditions can be arbitrarily selected. After drying at 50-80 ° C, 0.1 at 100-160 ° C
How to foam by exposing for about 3 minutes, or 12
It is also possible to perform drying and foaming simultaneously by heating at 0 to 160 ° C. for about 1 to 5 minutes.

[0026]

EXAMPLES The present invention will be described in detail below with reference to examples, but the present invention is not limited thereto. In Examples and Comparative Examples, parts or% means parts by weight or% by weight unless otherwise specified.
Is shown.

Examples 1 to 7 and Comparative Examples 1 to 4 (Production of Aqueous Acrylic Copolymer Aqueous Emulsion) A reactor equipped with a stirrer, a reflux condenser and a dropping funnel was used.
70 parts of water, Neogen T (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 0.1
Charge 5 parts and 0.1 part ammonium persulfate,
106 parts of the monomer composition shown in Table 1 below, 53 parts of water,
4 parts of Rebenol WZ (manufactured by Kao Corporation), 3 parts of Nonion NS-230 (manufactured by NOF CORPORATION), and 0.2 parts of ammonium persulfate were weighed and emulsified using a homomixer. An initial charge was performed using 7% of the liquid.
Then, the temperature was raised to 80 ° C. to carry out initial polymerization for 30 minutes, and subsequently 93% of the monomer emulsion was added dropwise over 2 hours. Further, the mixture was kept at 80 ° C. for 2 hours for post-polymerization and cooled to room temperature. Then, the reaction product was filtered through a 100-mesh screen, and the pH was adjusted to 8.5 with 25% aqueous ammonia, and the solid content concentration was adjusted to 45% with water.
The results of Tg (measured by a differential scanning calorimeter) and gel fraction of the obtained emulsion are also shown in Table 1.

[0028]

[Table 1]

* 1 EA: ethyl acrylate BA: butyl acrylate 2-EHA: 2-ethylhexyl acrylate MMA: methyl methacrylate AN: acrylonitrile MAA: methacrylic acid MAM: methacrylamide N-mAM: N-methylol acrylamide EDMA: ethylene glycol dimetamethacrylate Acrylate Tg: Glass transition temperature

(Preparation of inorganic filler paste) 39 parts of water,
Dispersant (Poise-520: manufactured by Kao Corporation) 1 part, defoaming agent (Homaster VL: manufactured by San Nopco) 0.6 part, aluminum hydroxide (Hijilite H-32: manufactured by Showa Denko KK)
85 parts, titanium oxide (R-630: manufactured by Ishihara Sangyo Co., Ltd.)
15 parts were mixed in a ball mill for 24 hours to prepare an inorganic filler paste (solid content concentration 70%). (Preparation of heat-expandable hollow microsphere slurry) Expancel 053 (manufactured by Nippon Philite Co., Ltd., solid content concentration 75)
%) 50 parts and 33 parts of water are stirred with a homomixer,
A slurry having a solid content concentration of 40% was prepared.

100 parts of the above acrylic copolymer emulsions (Examples 1 to 7 and Comparative Examples 1 to 4) (45 parts of solid content), 200 parts of the above inorganic filler paste (140 parts of solid content), And 30 parts of the above thermally expandable hollow microsphere slurry (12 parts in terms of solid content) are mixed and uniformly mixed, and then a predetermined amount of a thickener (ASE-60: manufactured by Rohm & Haas Co.) and aqueous ammonia are added. , Viscosity about 5000cps
To prepare a coating composition.

This coating composition was applied onto aluminum hydroxide paper (fire protection grade 1, 120 g / m ² ) by the knife coating method so that the dry weight of the coated body was 120 g / m ² .
After drying at 80 ° C. for 4 minutes, foaming was performed at 140 ° C. for 50 seconds. The foamed coating thus obtained was evaluated by the following methods and the results are shown in Table 2.

Test method Foaming ratio: (thickness after foaming-thickness of base paper) / (thickness before foaming-thickness of base paper)

Scratch resistance: The appearance was observed by scratching with a thumb nail, and there were ○ (no abnormalities), Δ (scratches were left on the surface and rubbing marks remained), and × (scratches were partially peeled off). It was judged according to the standard.

Blocking resistance: 5 kg of foamed surfaces are superposed on each other, and the conditions are 40 ° C. and 90% RH (relative humidity).
/ Cm ² was applied and the plate was left for 24 hours. After that, the superposed surfaces were peeled off, and judgment was made based on the criteria of ◯ (no resistance), Δ (with resistance), and × (breakage of material).

Low-temperature flexibility: The foam coating was left in a chamber at -10 ° C. for 24 hours, the foam surface was folded outward in the chamber, and the state of the fold was observed. ○ (no abnormality), △ (one Partial cracking), x (overall cracking).

Flame retardance: A foamed coating having a length of 300 mm and a width of 40 mm was hung vertically, burned from the bottom with a burner for 5 seconds, and the burning time after removing the flame was observed. ○ (no burning) △ Judgment was made based on the criteria of (afterflame of 5 seconds or less after burning) and x (afterflame of 5 seconds or more after burning).

[0038]

[Table 2]

Examples 8-10, Comparative Examples 5-7 Other than changing the acrylic copolymer emulsion used in Example 1 above and the above-mentioned inorganic filler paste in the quantitative ratio of aluminum hydroxide and titanium oxide. The inorganic filler paste prepared in the same manner and the above-mentioned heat-expandable hollow microsphere slurry were mixed in the proportions shown in Table 3 in terms of solid content, and a coating composition was prepared in the same manner as in Example 1. In Examples 9 and 10 and Comparative Examples 6 and 7, a predetermined amount of Celmic AN (manufactured by Sankyo Chemical Co., Ltd.), which is a dinitrosopentamethylenetetramine-based foaming agent, was blended as an organic foaming agent. Each coating composition was applied to aluminum hydroxide paper in the same manner as in Example 1, dried and foamed to prepare a foamed coated body. Table 3 shows the test results of the obtained foam coated body.

[0040]

[Table 3]

[0041]

INDUSTRIAL APPLICABILITY As described above, the present invention has excellent flame retardancy without using vinyl chloride which generates harmful chlorine gas during a fire or incineration, and is required as an essential requirement for a foamed wallpaper. A heat-expandable coating composition for wall decoration suitable for producing a wallpaper having good physical properties such as scratch resistance, abrasion resistance, blocking resistance, bending resistance at low temperature, and foamability.

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Claims (4)

[Claims] 1. 100 parts by weight of an acrylic copolymer aqueous emulsion having a glass transition temperature of −45 ° C. to −15 ° C. and a gel fraction of 70% by weight or more (as solid content), and 200 to 550 parts by weight of an inorganic filler. And a heat-expandable coating composition for wall decoration, which comprises 5 to 40 parts by weight of heat-expandable hollow microspheres. 2. The acrylic copolymer is an acrylic acid ester monomer 99 having an alkyl group having 2 to 9 carbon atoms.
55% by weight and 0.5 to 6% by weight of an unsaturated monomer that forms a crosslink during polymerization, 0.5 to 6% by weight of a carboxyl group-containing unsaturated monomer, and other polymerizable unsaturated monomers The thermally expandable coating composition for wall decoration according to claim 1, which is obtained by emulsion-copolymerizing a monomer mixture consisting of 0 to 44% by weight. 3. The inorganic filler is aluminum hydroxide 2
0 to 400 parts by weight and other inorganic fillers 0 to 150
The heat-expandable coating composition for wall decoration according to claim 1 or 2, which comprises 1 part by weight. 4. 100 parts by weight of an aqueous acrylic copolymer emulsion having a glass transition temperature of −45 ° C. to −15 ° C. and a gel fraction of 70% by weight or more (as solid content), and 200 to 550 parts by weight of an inorganic filler. Parts, and 5 to 40 parts by weight of heat-expandable hollow microspheres, the coating composition according to claim 1, 2 or 3 is printed or applied on a base material for wallpaper, and then heated to form the coating composition. A wallpaper with an uneven pattern obtained by expanding.