Composition for building materials

Abstract

The present invention addresses the problem of providing a composition for building materials that is capable of forming a cured body which has high deformability in response to external force and can effectively inhibit cracking of wallpaper. The composition for building materials is used by being mixed with water. The composition for building materials includes at least one powder selected from the group consisting of gypsum, calcium carbonate, talc, and clay minerals. With respect to a cured body 7 days after the start of kneading of a kneaded mixture obtained by mixing the composition for building materials with water, the bending angle as measured in accordance with the JIS A 6909(2014) 7.25 flexibility test is 40 degrees or greater. With respect to the cured body of the kneaded mixture, the maximum shear strength measured at a speed of 10 mm / min is 60 N / cm or greater.

Description

Composition for building materials

[0001] The present invention relates to a building material composition useful as a surface preparation material and a joint treatment material.

[0002] When constructing a wall using multiple gypsum boards, it is common practice to apply wallpaper or water-based paint to the surface of the gypsum boards to conceal the surface or to enhance the aesthetic appeal of the wall. Where gypsum boards butt together, joints are formed by the outer edges of each board. In addition to these inevitably occurring joints, uneven surfaces or deep grooves may also occur on surfaces formed with gypsum boards for various reasons. Therefore, before applying wallpaper or water-based paint to the surface of the gypsum boards forming the wall, a primer or joint treatment material is used to fill in the joints and other recessed areas, creating a smooth surface with the gypsum board surface.

[0003] Incidentally, cracking of wallpaper at the joints of board materials such as gypsum board and plywood is becoming a problem. The causes of wallpaper cracking are thought to be not only due to aging, but also to building vibrations caused by typhoons, earthquakes, etc. To prevent wallpaper cracking, conventional measures have been taken to reinforce the joints by combining paper or fiberglass tape with joint treatment materials, or to suppress the displacement of the joints by using metal materials to connect the base materials. However, these measures have the disadvantage of increasing the number of work steps.

[0004] Conventional known substrate preparation materials and joint treatment materials of this type include, for example, those containing powder components such as hemihydrate gypsum or calcium carbonate and resin components such as vinyl acetate-ethylene synthetic resin or vinyl acetate-acrylic synthetic resin (see Patent Documents 1 to 5).

[0005] Japanese Patent Publication No. 56-50155, Japanese Patent Publication No. 59-156947, Japanese Patent Publication No. 2-302350, International Publication No. 2002 / 004569, International Publication No. 2016 / 152594

[0006] However, when using previously known surface preparation materials and joint treatment materials, the deformability of the resulting hardened bodies against external forces was insufficient, and it could not be said that they could adequately prevent cracking of wallpaper.

[0007] Therefore, the object of the present invention is to provide a building material composition that can produce a hardened body with sufficient deformability against external forces.

[0008] The present invention provides a building material composition for use in mixture with water, comprising at least one powder selected from the group consisting of gypsum, calcium carbonate, talc, and clay minerals, wherein a hardened body (125 mm in length, 50 mm in width, 1 mm in thickness) obtained by mixing 100 parts by mass of the building material composition with 40 to 120 parts by mass of water per 100 parts by mass of the building material composition has a bending angle of 40 degrees or more measured in accordance with the JIS A6909 (2014) 7.25 flexibility test for 7 days after the start of mixing of the mixture, and a hardened body (195 mm in length, 200 mm in width, 0.5 mm in thickness) obtained for 24 hours after the start of mixing of the mixture has a maximum shear strength of 60 N / cm or more measured at a speed of 10 mm / min.

[0009] Figures 1(a) and 1(b) are schematic diagrams showing jigs for conducting flexibility tests. Figures 2(a) and 2(b) are explanatory diagrams showing how the flexibility test is performed. Figures 3(a) and 3(b) are schematic diagrams showing jigs for measuring shear strength. Figure 4 is an explanatory diagram showing how shear strength is measured.

[0010] The present invention will be described below based on its preferred embodiments. The present invention relates to a building material composition. The building material composition of the present invention is suitably used, for example, in forming walls and ceilings of buildings, but is not limited to these parts, and may be applied to other parts of buildings. The building material composition of the present invention includes, as one of its constituent components, at least one powder selected from the group consisting of gypsum, calcium carbonate, talc, and clay minerals. This powder is the main material in the building material composition, and the proportion of the powder in the building material composition is preferably 40% by mass or more, as will be described later.

[0011] As gypsum included in the building material composition, anhydrous gypsum and hemihydrate gypsum can be used. Hemihydrate gypsum is calcium sulfate 1 / 2 hydrate [CaSO4] ４ ・1 / 2H ２ Hemihydrate gypsum is obtained by calcining dihydrate gypsum. Furthermore, hemihydrate gypsum readily changes to dihydrate gypsum through a chemical reaction (hydration reaction) with water. As hemihydrate gypsum, β-type hemihydrate gypsum obtained by calcining gypsum alone or in mixtures of natural gypsum, by-product gypsum, flue gas desulfurization gypsum, and waste gypsum in the atmosphere, or α-type hemihydrate gypsum obtained by calcining in water can be used. A mixture of α-type hemihydrate gypsum and β-type hemihydrate gypsum can also be used. When α-type hemihydrate gypsum is used, the shear strength of the hardened body obtained from the building material composition is higher compared to when β-type hemihydrate gypsum is used. Of these gypsums, it is preferable to use hemihydrate gypsum from the viewpoint that the hardened body obtained from the building material composition is easily deformable and less prone to cracking.

[0012] As for calcium carbonate, crushed natural limestone or calcium carbonate synthesized by blowing carbon dioxide into an aqueous suspension of calcium hydroxide can be used.

[0013] For talc, silicate minerals mainly containing magnesium can be used. For example, the composition formula Mg ３ Si ４ O １０ (OH) ２ You can use what is represented by [the symbol].

[0014] Examples of clay minerals that can be used include montmorillonite, attapulgite, meerschmitt, and bentonite.

[0015] The above-mentioned powders can be used individually or in combination of two or more. Of the above-mentioned powders, gypsum and calcium carbonate can be used, and hemihydrate gypsum is particularly preferred, from the viewpoint that the hardened body obtained from the building material composition is easily deformable and less prone to cracking.

[0016] The specific surface area of the powder is appropriately selected in consideration of the specific location where the building material composition of the present invention is applied, workability, and the like. For example, when used as a caulking material for undercoating between plates, those having a relatively large specific surface area to the extent that workability is not impaired are also acceptable. The general specific surface area is about 2000 cm ２ / g or more and 20000 cm ２ / g or less. When using gypsum as the powder, its specific surface area is preferably about 2000 cm ２ / g or more and 10000 cm ２ / g or less, more preferably about 2500 cm ２ / g or more and 4500 cm ２ / g or less. When using calcium carbonate, it is about 2500 cm ２ / g or more and 10000 cm ２ / g or less, particularly preferably about 3000 cm ２ / g or more and 8000 cm ２ / g or less. This specific surface area is the Blaine specific surface area value measured using the Blaine air permeability apparatus described in JIS R5201 (2015).

[0017] The content of the powder in the building material composition of the present invention is preferably 40% by mass or more, more preferably 50% by mass or more, and even more preferably 53% by mass or more, from the viewpoint of making the cured body obtained from the building material composition easy to deform and less likely to crack. Also, the content of the powder in the building material composition of the present invention is preferably 90% by mass or less, more preferably 85% by mass or less, and even more preferably 84% by mass or less, from the viewpoint of improving workability.

[0018] One of the features of the building material composition of the present invention is that the hardened mixture obtained by mixing it with water is easily deformable and resistant to cracking when bent. From this viewpoint, when the bending angle of a hardened mixture (length 125 mm, width 50 mm, thickness 1 mm) obtained by mixing 100 parts by mass of the building material composition with 40 to 120 parts by mass of water per 100 parts by mass of the building material composition, after 7 days from the start of mixing, is measured in accordance with "JIS A6909 (2014) 7.25 Flexibility Test", the angle at which a hairline crack occurs in the hardened mixture (this angle is also called the "first angle") θ １ When the angle is 40 degrees or higher, the hardened body becomes sufficiently deformable against external forces. From this viewpoint, θ １ The first angle θ is preferably 50 degrees or more, and more preferably 90 degrees or more. １ There is no particular upper limit to this value, and a larger value is preferable, but the first angle θ should be around 95 degrees. １ If the value is large, the objective of the present invention is fully achieved. In this specification, "hairline crack" refers to a fine crack of any width that is first observed in a hardened material during the bending process. The length of the crack is irrelevant.

[0019] In relation to the first angle mentioned above, the bending of the hardened body is continued even after measuring the first angle, and the angle at which the hardened body 12 completely breaks (this angle is also called the "second angle") θ ２ When measuring, the second angle θ ２ This is the first angle θ mentioned above. １ Provided the above conditions are met, the second angle θ is preferably 40 degrees or more, more preferably 60 degrees or more, and even more preferably 90 degrees or more. ２ There is no particular upper limit to this value, and a larger value is preferable, but the second angle θ is around 100 degrees. ２ If the value is large, the objective of the present invention is fully achieved. Note that when measuring the bending angle, if the hardened body completely fractures without any hairline cracks being observed, then θ is the value. １ = θ ２ That is the case.

[0020] first angle θ １ and the second angle θ ２The detailed measurement method will be explained in the examples described later. The bending speed of the hardened body is the first angle θ １ and the second angle θ ２ The inventors have confirmed that setting the bending speed between 100 degrees / min and 140 degrees / min does not affect the measurement results. Furthermore, when preparing the compound for manufacturing the hardened body, as described above, 40 to 120 parts by mass of water are added to 100 parts by mass of the building material composition. The inventors have also confirmed that adding water within this range does not result in any difference in the physical properties of the resulting hardened body. Typically, it is preferable to manufacture the hardened body by adding 40 to 75 parts by mass of water to 100 parts by mass of the building material composition. In addition, JIS A6909 (2014) 7.25 specifies that the bending angle should be measured on a hardened body 14 days after the start of compounding, but in the present invention, the hardened body 7 days after the start of compounding is used as the target for measurement. However, the inventors have confirmed that after 7 days from the start of mixing the compound, no substantial difference is observed in various physical properties, including the strength of the hardened body.

[0021] Furthermore, the fact that the hardened body (195 mm in length, 200 mm in width, and 0.5 mm in thickness) obtained 24 hours after the start of mixing the aforementioned building material composition with water has a maximum shear strength of 60 N / cm or more measured at a speed of 10 mm / min indicates that the hardened body is easily deformable and resistant to cracking when bent. From this viewpoint, a maximum shear strength of 70 N / cm or more is more preferable, and 100 N / cm or more is even more preferable. There is no particular upper limit to the maximum shear strength, and a higher value is desirable, but if the maximum shear strength is as high as 150 N / cm, the objective of the present invention is sufficiently achieved.

[0022] In relation to the maximum shear strength mentioned above, the shear strength at which the first crack occurs in the hardened material between the application of shear force and the observation of the maximum shear strength (this shear strength is also called the "first crack shear strength") is approximately the same as the maximum shear strength. In other words, the shear strength at which the first crack occurs in the hardened material roughly corresponds to the maximum shear strength.

[0023] The first crack that occurs during the measurement of the first crack shear strength refers to the hairline crack, which was explained earlier in relation to the flexibility test.

[0024] In order to make the cured body produced from the building material composition of the present invention more deformable and less prone to cracking when bent, it is advantageous for the building material composition to contain other components in addition to the powder components described above. For example, it is preferable to add a synthetic resin to the building material composition. Using a vinyl acetate-ethylene synthetic resin as the synthetic resin that can be added to the building material composition is preferable because it makes the cured body even more deformable and less prone to cracking when bent. It is also preferable to use two or more of the vinyl acetate-acrylic synthetic resin, vinyl acetate-ethylene synthetic resin, and acrylonitrile-butadiene copolymer in combination to obtain a similar effect.

[0025] Vinyl acetate-ethylene synthetic resins are copolymers of vinyl acetate and ethylene. It is preferable that the glass transition temperature of vinyl acetate-ethylene synthetic resins be -30°C or higher, as this makes the cured material more easily deformable and less prone to cracking when bent. From this viewpoint, it is even more preferable that the glass transition temperature of vinyl acetate-ethylene synthetic resins be -25°C or higher, even more preferable that it be -20°C or higher, and even more preferable that it be -13°C or higher. Similarly, it is preferable that the glass transition temperature of vinyl acetate-ethylene synthetic resins be 5°C or lower, even more preferable that it be 0°C or lower, and even more preferable that it be -5°C or lower. Considering the above, it is preferable that the glass transition temperature of vinyl acetate-ethylene synthetic resins be -30°C or higher and 5°C or lower, even more preferable that it be -25°C or higher and 0°C or lower, even more preferable that it be -20°C or higher and -5°C or lower, and even more preferable that it be -13°C or higher and -5°C or lower. The glass transition temperature is measured by differential scanning calorimeter.

[0026] In the present invention, although not particularly limited, as the vinyl acetate-ethylene synthetic resin, a re-emulsified dry powder resin obtained by spray-drying a protective colloid resin emulsion of the resin can be used, for example. It is also possible to use a commercially available product as the vinyl acetate-ethylene synthetic resin. Examples of such commercially available products include FX2350 (trade name) manufactured by Celanese Corporation, and Vinibran (registered trademark) 3483Y manufactured by Nisshin Chemical Industry Co., Ltd.

[0027] When the vinyl acetate-ethylene synthetic resin is blended in the composition for building materials, the blending amount is preferably 8 parts by mass or more, more preferably 10 parts by mass or more, still more preferably 11 parts by mass or more, based on 100 parts by mass of the powder. As a result, the cured body becomes more easily deformable and more resistant to cracking under bending. For the same reason, the blending amount of the vinyl acetate-ethylene synthetic resin is preferably 23 parts by mass or less, more preferably 22 parts by mass or less, still more preferably 15 parts by mass or less, based on 100 parts by mass of the powder. Considering the above, the blending amount of the vinyl acetate-ethylene synthetic resin is preferably 8 parts by mass or more and 23 parts by mass or less, more preferably 10 parts by mass or more and 22 parts by mass or less, still more preferably 11 parts by mass or more and 15 parts by mass or less, based on 100 parts by mass of the powder.

[0028] The vinyl acetate-acrylic synthetic resin is a copolymer of vinyl acetate and acrylic acid or its derivative or methacrylic acid or its derivative. Examples of the acrylic acid derivative include esters of acrylic acid, specifically esters of acrylic acid and lower monohydric saturated aliphatic alcohols such as methyl acrylate. Examples of the methacrylic acid derivative include esters of methacrylic acid, specifically esters of methacrylic acid and lower monohydric saturated aliphatic alcohols such as methyl methacrylate.

[0029] Vinyl acetate-acrylic synthetic resins preferably have a glass transition temperature of 7°C or higher from the viewpoint of further increasing the shear strength of the cured body. From this viewpoint, the glass transition temperature of the vinyl acetate-acrylic synthetic resin is more preferably 8°C or higher. From the same viewpoint, the glass transition temperature of the vinyl acetate-acrylic synthetic resin is preferably 50°C or lower, more preferably 20°C or lower, and even more preferably 10°C or lower. Considering the above, the vinyl acetate-acrylic synthetic resin preferably has a glass transition temperature of 7°C or higher and 50°C or lower, more preferably 8°C or higher and 20°C or lower, and even more preferably 8°C or higher and 10°C or lower. The method for measuring the glass transition temperature is as described above.

[0030] In the present invention, although not particularly limited, as the vinyl acetate-acrylic synthetic resin, a re-emulsified dry powder resin obtained by spray-drying a protective colloid resin emulsion of the resin can be used. It is also possible to use a commercially available product as the vinyl acetate-acrylic synthetic resin. Examples of such commercially available products include Boncoat CF-2800 (trade name) manufactured by DIC Corporation, and Vinibran (registered trademark) A68J1 and Vinibran (registered trademark) A70J2M manufactured by Nissin Chemical Industry Co., Ltd.

[0031] When the vinyl acetate-acrylic synthetic resin is blended in the composition for building materials, the blending amount is preferably 8 parts by mass or more, more preferably 10 parts by mass or more, and even more preferably 12 parts by mass or more with respect to 100 parts by mass of the powder. As a result, the cured body becomes more easily deformable and more resistant to cracking under bending. For the same reason, the blending amount of the vinyl acetate-acrylic synthetic resin is preferably 21 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 18 parts by mass or less with respect to 100 parts by mass of the powder. Considering the above, the blending amount of the vinyl acetate-acrylic synthetic resin is preferably 8 parts by mass or more and 21 parts by mass or less, more preferably 10 parts by mass or more and 20 parts by mass or less, and even more preferably 12 parts by mass or more and 18 parts by mass or less with respect to 100 parts by mass of the powder.

[0032] Acrylonitrile-butadiene copolymer is a copolymer of acrylonitrile and butadiene. The physical properties of acrylonitrile-butadiene copolymer change depending on the amount of acrylonitrile (AN) bonded to it. In the present invention, an acrylonitrile-butadiene copolymer is used in which the amount of AN in all copolymer components is preferably 15 parts by mass or more, more preferably 20 parts by mass or more, and even more preferably 31 parts by mass or more. This makes the cured body more easily deformable and more less prone to cracking when bent. For the same reason, in acrylonitrile-butadiene copolymer, the amount of AN in all copolymer components is preferably 50 parts by mass or less, more preferably 43 parts by mass or less, and even more preferably 40 parts by mass or less.

[0033] Commercially available acrylonitrile-butadiene copolymers can be used. Examples of such commercially available products include Nipol® 1411C (trade name) manufactured by Nippon Zeon Corporation.

[0034] When acrylonitrile-butadiene copolymer is incorporated into a building material composition, the amount is preferably 7 parts by mass or more, more preferably 10 parts by mass or more, and even more preferably 12 parts by mass or more, per 100 parts by mass of the powder. This makes the cured body more easily deformable and less prone to cracking when bent. For the same reason, the amount of acrylonitrile-butadiene copolymer is preferably 35 parts by mass or less, and even more preferably 30 parts by mass or less, per 100 parts by mass of the powder. Considering the above, the amount of acrylonitrile-butadiene copolymer is preferably 7 parts by mass or more and 35 parts by mass, more preferably 10 parts by mass or more and 30 parts by mass or less, and even more preferably 12 parts by mass or more and 30 parts by mass or less, per 100 parts by mass of the powder.

[0035] The building material composition may contain synthetic resins other than the vinyl acetate / acrylic synthetic resin and / or vinyl acetate / ethylene synthetic resin and / or acrylonitrile / butadiene copolymer described above. However, from the viewpoint of making the cured body more easily deformable and less prone to cracking when bent, it is preferable that the building material composition contains only vinyl acetate / acrylic synthetic resin and / or vinyl acetate / ethylene synthetic resin and / or acrylonitrile / butadiene copolymer as synthetic resins, and that it does not contain any other synthetic resins. The building material composition may contain two or more resins. The total amount of these resins is preferably 16 parts by mass or more, and more preferably 25 parts by mass or more, per 100 parts by mass of the powder. This makes the cured body more easily deformable and less prone to cracking when bent. For the same reason, the total amount of the resins is preferably 70 parts by mass or less, more preferably 65 parts by mass or less, and even more preferably 35 parts by mass or less, per 100 parts by mass of the powder. Considering the above, the total amount of resin added is preferably 16 parts by mass or more and 70 parts by mass or less, more preferably 25 parts by mass or more and 65 parts by mass or less, and even more preferably 25 parts by mass or more and 35 parts by mass or less, per 100 parts by mass of the powder.

[0036] In addition to the components described above, the building material composition may also contain additives that can improve the properties of the hardened body obtained from the building material composition. For example, at least one additive selected from the group consisting of aggregates, lightweight aggregates, adhesives, thickeners, setting time adjusters, colorants, waterproofing agents, pH stabilizers, defoamers, antifungal agents, plasticizers, lubricants, slippers, and humidity control agents can be added. The total amount of these additives is preferably 10 to 40 parts by mass, more preferably 11 to 30 parts by mass, and even more preferably 12 to 22 parts by mass, per 100 parts by mass of the powder.

[0037] Examples of the aggregate include inorganic aggregates such as magnesium silicate, magnesium carbonate, magnesium hydroxide, and silica. Examples of the lightweight aggregate include mica, vermiculite, diatomaceous earth, silica balloons (including shirasu balloons, etc.), glass microbeads, polymer spheres, vermiculite, perlite, and artificial lightweight aggregates (e.g., slag). Of these, vermiculite is produced by firing and expanding minerals such as biotite at high temperatures. Perlite is produced by firing and expanding perlite or obsidian at high temperatures. Examples of the binder include polyvinyl alcohol. Examples of the thickener include methylcellulose, hydroxyethylcellulose, hydroxypropylmethylcellulose, methylhydroxyethylcellulose, ethylhydroxyethylcellulose, methylhydroxypropylcellulose, and carboxymethylcellulose, as well as salts thereof. As the thickening agent, polysaccharides such as dextran, chitin, chitosan, xylan, xanthan gum, gellan gum, mannan, galactan, glucan, arabinoxylan, arginate, guar gum, and guar gum derivatives, polyacrylamides, pregelatinized starch, and starch derivatives may also be used. Examples of setting time modifiers include citrates such as sodium citrate, succinates, acetates, malates, borates such as borax, sucrose, hexametaphosphates, ethylenediaminetetraacetate, diethylenetriaminepentaacetic acid, starch, protein hydrolysates, and gypsum dihydrate.

[0038] The building material composition of the present invention is suitably used, for example, as a base preparation material composition for interior walls or ceilings. In particular, it is suitably used as a joint treatment material composition between boards. In this case, the building material composition can be kneaded with an appropriate amount of water to make a base preparation material for interior walls or ceilings. Alternatively, the building material composition can be kneaded with an appropriate amount of water to make a joint treatment material composition between boards. The amount of water to be added to the building material composition is 40 parts by mass or more and 120 parts by mass or less per 100 parts by mass of the building material composition to achieve sufficient curability and workability, and from this viewpoint, it is even more preferable to use 40 parts by mass or more and 75 parts by mass or less. The joint treatment material composition prepared in this way can be filled into the joints that occur when making a wall surface with multiple boards, for example, multiple gypsum boards, and then hardened. Alternatively, the base preparation material can be coated onto part or all of the gypsum board and hardened to perform a smoothing treatment on the wall surface. After smoothing the wall surface in this manner, wallpaper or water-based paint can be applied or attached to the base material using various methods. Specifically, wallpaper can be applied or paint applied using rollers, brushes, airless sprayers, etc. As described above, the cured body obtained from the building material composition of the present invention is easily deformable and resistant to cracking when bent, so cracking of wallpaper or paint applied to the cured body is effectively suppressed.

[0039] With respect to the above embodiments, the present invention further discloses the following building material compositions: [1] A building material composition used in combination with water, comprising at least one powder selected from the group consisting of gypsum, calcium carbonate, talc, and clay minerals, wherein a hardened body (length 125 mm, width 50 mm, thickness 1 mm) obtained by mixing 100 parts by mass of the building material composition with 40 to 120 parts by mass of water per 100 parts by mass of the building material composition has a bending angle of 40 degrees or more measured in accordance with the JIS A6909 (2014) 7.25 flexibility test 7 days after the start of mixing of the mixture, and a hardened body (length 195 mm, width 200 mm, thickness 0.5 mm) obtained 24 hours after the start of mixing of the mixture has a maximum shear strength of 60 N / cm or more measured at a speed of 10 mm / min. [2] The building material composition according to [1], further comprising a vinyl acetate-ethylene synthetic resin. [3] The building material composition according to [1], further comprising at least two of the vinyl acetate-ethylene synthetic resin, vinyl acetate-acrylic synthetic resin, and acrylonitrile-butadiene copolymer. [4] The building material composition according to [3], comprising 8 to 21 parts by mass of the vinyl acetate-acrylic synthetic resin per 100 parts by mass of the powder. [5] The building material composition according to [3] or [4], wherein the glass transition temperature of the vinyl acetate-acrylic synthetic resin is 7°C or higher and 50°C or lower. [6] The building material composition according to [2] or [3], comprising 8 to 23 parts by mass of the vinyl acetate-ethylene synthetic resin per 100 parts by mass of the powder. [7] The building material composition according to [2], [3] or [6], wherein the glass transition temperature of the vinyl acetate-ethylene synthetic resin is -30°C or higher and 5°C or lower. [8] The building material composition according to [3], [4], or [5], comprising 7 to 35 parts by mass of the acrylonitrile-butadiene copolymer per 100 parts by mass of the powder. [9] The building material composition according to any one of [1] to [8], further comprising at least one additive selected from the group consisting of aggregates, lightweight aggregates, adhesives, thickeners, and setting time adjusters.

[10] The building material composition according to any one of [1] to [9], which is a substrate preparation material composition for interior walls or ceilings.

[11] A building material composition according to any one of [1] to [9], which is a joint treatment material composition between boards.

[0040] The present invention will be described in more detail below with reference to examples. However, the scope of the present invention is not limited to these examples.

[0041] [Examples 1 to 11 and Comparative Examples 1 to 7] Compositions were prepared by mixing the components shown in Table 1 below in the amounts shown in the table. The amounts shown in the table refer to parts by mass. In the table, the Blaine specific surface area of ​​hemihydrate gypsum is 3280 cm². ２ The values ​​were / g. In addition, in the same table, the glass transition temperature of vinyl acetate / acrylic synthetic resin was 8°C. The glass transition temperature of vinyl acetate / ethylene synthetic resin was -7°C. Furthermore, in the same table, "other additives" refers to aggregates, lightweight aggregates, binders, thickeners, setting time adjusters, defoamers, pH stabilizers, and antifungal agents. 100 parts by mass of each composition having the composition shown in the table and 50 parts by mass of water were mixed at 65 rpm for 1 minute and 30 seconds using a Hobart-type mixer manufactured by Kansai Kiki Seisakusho Co., Ltd. to prepare a paste-like mixture.

[0042] [Examples 12 to 14 and Comparative Examples 8 and 9] Compositions were prepared by mixing the components shown in Table 2 below in the amounts shown in the table. The amounts shown in the table refer to parts by mass. In the table, the Blaine specific surface area of ​​calcium carbonate is 5000 cm². ２ The amount was / g. A paste was prepared by kneading 100 parts by mass of each composition having the composition shown in the table with 54 parts by mass of water. The paste was prepared in the same manner as in Example 1, except for the above.

[0043] [Examples 15 to 20 and Comparative Examples 10 to 14] Compositions were prepared by mixing the components shown in Table 3 below in the amounts shown in the table. The amounts shown in the table refer to parts by mass. In the case of the acrylonitrile-butadiene copolymer in the table, the amount of AN per 100 parts by mass of the copolymer was 38.5 parts by mass. Otherwise, the kneaded product was prepared in the same manner as in Example 1.

[0044] [Flexibility Test] Using the kneaded material obtained from the compositions of the examples and comparative examples, a cured body was manufactured according to the following procedure, and a flexibility test was performed on the cured body using the following method. A rectangular plate 10 made of polyvinyl chloride (15 cm long, 7 cm wide, 0.5 mm thick) and a rectangular mold 11 made of polyvinyl chloride (outer circumference: 15 cm long, 7.5 cm wide, 1 mm thick; inner circumference: 12.5 cm long, 5 cm wide) shown in Figure 1(a) were overlapped to form a recess. The kneaded material was applied to this recess, and the kneaded material that had spilled out of the recess was scraped off and removed. The mixture was then left to harden for 7 days from the start of mixing in an environment of 23 ± 2°C and 50 ± 5% RH, and a test piece 13 with the cured body 12 was obtained as shown in Figure 1(b).

[0045] The bending angle of the hardened body 12 obtained in this manner was measured in accordance with JIS A6906 (2014) 7.25 Flexibility Test. As shown in Figure 2(a), the measurement was performed on the hardened body 12 formed on the plate 10 after removing the mold 11. The surface 12a on which the kneaded material was applied to the hardened body 12 was facing outwards, and the opposite surface, i.e., the approximately vertical center of the outer surface 10a of the plate 10, was brought into contact with a horizontally fixed steel rod 14 with a diameter of 1 cm. From this state, the test piece 13 was gradually bent, and the first angle θ at which a hairline crack occurred in the hardened body 12 was observed visually. １ (See Figure 2(b)) was measured. The bending of the test piece 13 was continued even after hairline cracks occurred in the hardened body 12, and the second angle θ at which the hardened body 12 completely fractured was measured. ２ (See Figure 2(b)) was also measured. The bending speed of the test piece 13 was set to 120 degrees / min. Measurements were taken for three samples, and the arithmetic mean was calculated to determine the first and second angles. The results are shown in Tables 1 to 3.

[0046] [Shear Strength] Using the kneaded material obtained from the compositions of the examples and comparative examples, a hardened body was manufactured according to the following procedure, and the shear strength of the hardened body was measured using the following method. As shown in Figure 3(a), two rectangular structural plywood sheets 20, 20 that meet the Japanese Agricultural Standards, with a length of 19.5 cm and a width of 10 cm, were prepared, and the two plywood sheets 20, 20 were placed on a horizontal table so that their vertical edges were touching, to form a test plate 21 with an overall size of 19.5 cm × 20 cm. A joint 22 was formed in this test plate 21 by butting the two plywood sheets together. As shown in Figure 3(b), the kneaded material was applied to the entire surface of one side of the test plate 21 (i.e., an area of ​​19.5 cm × 20 cm) to a thickness of 0.5 mm to prepare a test piece 23. After leaving the test specimen 23 undisturbed for 12 hours in an environment of 23±2°C and 50±5%RH, the kneaded material was applied again to the thinned areas of the joints on the test specimen 23, and the applied surface was smoothed. Then, the test specimen 23 was left undisturbed for 24 hours in an environment of 23±2°C and 50±5%RH until it reached a constant weight. This formed a hardened body 24 of the kneaded material over the entire surface of one side of the test plate 21, which consisted of two plywood sheets 20, 20. Next, the test specimen 23 was mounted on a tensile testing machine (Shimadzu Corporation's Autograph®) using a special jig. When mounting, the joints 22 of the test specimen 23 were positioned in the center of the tensile testing machine. With one plywood 20 (for example, the left plywood 20 in Figure 4) fixed in the test specimen 23 attached to the tensile testing machine, the other plywood 20 (for example, the right plywood 20 in Figure 4) was displaced in the direction D1 of the arrow shown in Figure 4. The displacement speed was set to 10 mm / min. The maximum tensile load generated by the displacement was measured, and this value was defined as the maximum shear strength. Measurements were performed on three test specimens 23, and the arithmetic mean was calculated to determine the maximum shear strength. The results are shown in Tables 1 to 3.

[0047] [Workability] Ten expert panelists were asked to evaluate the workability of the aforementioned mixture applied to a vinyl chloride board for flexibility testing, according to the following criteria: 3: Good workability. 2: Workability without problems. 1: Workability is hindered. The average of the total scores was calculated, and workability was evaluated in the following categories. The results are shown in Tables 1 to 3. A: Average score of 2.5 points or higher. B: Average score of 1.5 points or higher but less than 2.5 points. C: Average score less than 1.5 points.

[0048]

[0049]

[0050]

[0051] As is clear from the results shown in Tables 1 to 3, the hardened materials produced from the compositions obtained in each example are extremely flexible against bending and are less prone to cracking even when subjected to large bending forces. Furthermore, the hardened materials produced from the compositions obtained in each example also have high resistance to shear force and are less prone to cracking even when subjected to large shear forces. In addition, it can be seen that most of the paste-like kneaded materials produced from the compositions obtained in the examples have good workability.

[0052] As described in detail above, the building material composition of the present invention exhibits high deformability against external forces in the hardened body obtained from the composition, and as a result, cracking of wallpaper can be effectively suppressed.

Claims

1. A building material composition for use in mixture with water, comprising at least one powder selected from the group consisting of gypsum, calcium carbonate, talc, and clay minerals, wherein a hardened body (125 mm in length, 50 mm in width, 1 mm in thickness) obtained by mixing 100 parts by mass of the building material composition with 40 to 120 parts by mass of water per 100 parts by mass of the building material composition has a bending angle of 40 degrees or more measured in accordance with the flexibility test of JIS A6909 (2014) 7.25 for 7 days after the start of mixing of the mixture, and a hardened body (195 mm in length, 200 mm in width, 0.5 mm in thickness) obtained 24 hours after the start of mixing of the mixture has a maximum shear strength of 60 N / cm or more measured at a speed of 10 mm / min.

2. The building material composition according to claim 1, further comprising a vinyl acetate-ethylene-based synthetic resin.

3. The building material composition according to claim 1, further comprising at least two of the following: vinyl acetate-ethylene synthetic resin, vinyl acetate-acrylic synthetic resin, and acrylonitrile-butadiene copolymer.

4. The building material composition according to claim 3, comprising 8 to 21 parts by mass of the vinyl acetate / acrylic synthetic resin per 100 parts by mass of the powder.

5. The building material composition according to claim 3 or 4, wherein the glass transition temperature of the vinyl acetate / acrylic synthetic resin is 7°C or higher and 50°C or lower.

6. The building material composition according to claim 2 or 3, comprising 8 to 23 parts by mass of the vinyl acetate-ethylene synthetic resin per 100 parts by mass of the powder.

7. The building material composition according to claim 2 or 3, wherein the glass transition temperature of the vinyl acetate-ethylene synthetic resin is -30°C or higher and 5°C or lower.

8. The building material composition according to claim 3, comprising 7 to 35 parts by mass of the acrylonitrile-butadiene copolymer per 100 parts by mass of the powder.

9. The building material composition according to any one of claims 1 to 3, further comprising at least one additive selected from the group consisting of aggregates, lightweight aggregates, binders, thickeners, and setting time adjusters.

10. A building material composition according to any one of claims 1 to 3, which is a substrate preparation material composition for interior walls or ceilings.

11. A building material composition according to any one of claims 1 to 3, which is a joint treatment material composition between boards.

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