Water redispersible composition and cement composition

Abstract

The invention provides a water redispersible composition and a cement composition comprising the same. The water redispersible composition comprises a vinyl acetate-ethylene copolymer, a dispersion matrix and an inorganic compound, wherein in a wide-angle X-ray diffraction pattern of the water redispersible composition, the signal intensity of a first characteristic peak at 20.5 DEG > = 2theta > = 20 DEG is relative to the signal intensity of a second characteristic peak at 20 DEG gt; the ratio of the signal intensity of the second characteristic peak when 2theta is greater than or equal to 19 degrees is 0.9-1.0; wherein the wide-angle X-ray diffraction pattern of the water redispersible composition is determined by using CuK alpha rays after the water redispersible composition is burnt at 400 DEG C for 40 minutes. By comprising the water redispersible composition, the cement composition according to the present invention has an adhesive strength degradation rate of less than 50% after immersion curing as defined by EN 12004-2: 2017 standard.

Description

TECHNICAL FIELD

[0001] The present application relates to a water-redispersible composition, in particular a water-redispersible composition comprising a vinyl acetate-ethylene (VAE) copolymer; the present application also relates to a cement composition comprising the water-redispersible composition. BACKGROUND

[0002] Generally, cement is composed of four main minerals (tricalcium silicate, dicalcium silicate, tricalcium aluminate, and tetracalcium aluminoferrite) and a small amount of secondary components (such as magnesium oxide, calcium oxide, etc.). When cement is mixed with water, hydration occurs immediately, generating various hydration products and crystals. Specifically, after cement is mixed with water, a series of complex physical and chemical reactions occur, causing the cement to change from a plastic slurry to a solid body with certain strength.

[0003] The surface of the cement particles in the cement composition will first undergo a hydration reaction to form a hydration product layer; as the hydration reaction continues, various hydration products gradually fill the space originally occupied by water, causing the various crystals in the cement composition to interweave and combine, and various hydration products with different sizes and shapes are formed. During the hydration process, water causes the cement particles to form clumps, resulting in water being trapped between the clumps, which cannot be effectively utilized. However, adding more water will cause subsequent quality problems such as reduced strength, longer setting time, etc. The hydration products with different morphologies and stacking structures are the key to determining the strength and adhesion of hardened cement. In order to adjust the adhesion, rheological properties, and / or weather resistance of the cement composition, organic polymer emulsions are often used in combination.

[0004] However, although polymer emulsion cement (i.e., a mixture of polymer emulsion and cement) can improve the water tightness of the cement composition and increase the tensile strength, the organic polymer emulsion can be affected by environmental factors such as temperature and humidity, causing the cement composition to become unstable, which requires the manufacturer to provide the user with a two-component form, but in actual use, this can cause problems such as uneven mixing and dispensing.

[0005] To eliminate the above-mentioned defects, manufacturers are actively developing water-redispersible polymer powders that can be advantageously used in dry mortar. However, if the water-redispersible polymer powder is combined into larger agglomerates, it can adversely affect the redispersibility, adhesion, or water resistance. Therefore, there is still a need to improve the water-redispersible polymer powder in order to overcome the deficiencies of the prior art. SUMMARY

[0006] In view of the deficiencies of the prior art, an object of the present invention is to provide a water-redispersible composition that enables cement compositions containing the composition to have good adhesive strength, and whose adhesive strength degradation rate is less than 50% under immersion curing conditions according to the EN 12004-2:2017 test method.

[0007] To achieve the aforementioned objective, the present invention provides a water-redispersible composition comprising a VAE copolymer, a dispersion matrix, and an inorganic compound; wherein, in the wide-angle X-ray diffraction spectra (WAXD spectra) of the water-redispersible composition, the ratio (I1 / I2) of the signal intensity (I1) of the first characteristic peak at 20.5° ≥ 2θ ≥ 20° to the signal intensity (I2) of the second characteristic peak at 20° > 2θ ≥ 19° is 0.9 to 1.0; wherein, the wide-angle X-ray diffraction spectra of the water-redispersible composition are obtained by measuring the water-redispersible composition using CuKα rays after it has been burned at 400°C for 40 minutes.

[0008] The present invention improves the water resistance of cement compositions by controlling the ratio of the signal intensity (I1) of the first characteristic peak to the signal intensity (I2) of the second characteristic peak in the wide-angle X-ray diffraction pattern of the water-redispersible composition after combustion at 400°C for 40 minutes to be 0.9 to 1.0. This improves the adhesion strength of the cement composition under immersion curing conditions and reduces the adhesion strength degradation rate.

[0009] Preferably, the ratio of the signal intensity of the first characteristic peak to the signal intensity of the second characteristic peak can be between 0.91 and 0.99, for example: 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98. It should be understood that the aforementioned ranges are continuous ranges, and each of the above specific values ​​can be used as the endpoint of another range.

[0010] Preferably, the content of the VAE copolymer, based on the weight of the water-redispersible composition, can be from 60 wt% to 90 wt%, but is not limited thereto. Optionally, the content of the VAE copolymer, based on the weight of the water-redispersible composition, can be 60 wt%, 61 wt%, 62 wt%, 63 wt%, 64 wt%, 65 wt%, 66 wt%, 67 wt%, 68 wt%, 69 wt%, 70 wt%, 71 wt%, 72 wt%, 73 wt%, 74 wt%, 75 wt%, 76 wt%, 77 wt%, 78 wt%, 79 wt%, 80 wt%, 81 wt%, 82 wt%, 83 wt%, 84 wt%, 85 wt%, 86 wt%, 87 wt%, 88 wt%, 89 wt%, 90 wt%, or a range between any two of the above values.

[0011] The VAE copolymer comprises structural units derived from vinyl acetate and structural units derived from ethylene. In some embodiments, the VAE copolymer consists only of structural units derived from vinyl acetate and structural units derived from ethylene. In other embodiments, the VAE copolymer may comprise structural units derived from other monomers besides the structural units derived from vinyl acetate and structural units derived from ethylene; for example, other monomers may include methyl methacrylate (MMA), butyl acrylate (BA), 2-ethylhexyl acrylate (2EHA), or combinations thereof, but are not limited thereto. Preferably, the content of vinyl acetate in the VAE copolymer may be higher than the content of ethylene. Furthermore, the structural units derived from ethylene may be derived from vinyl neodecanoate, such as VeoVa, which is available from Hexion. TM 10, but not limited to this.

[0012] In some embodiments, the content of ethylene-derived structural units in the VAE copolymer may be from 5 wt% to 45 wt%, but is not limited thereto. Optionally, the content of ethylene-derived structural units in the VAE copolymer may be 5 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, 35 wt%, 40 wt%, or 45 wt%, or may be within a range consisting of any two of the above values.

[0013] In some embodiments, the content of vinyl acetate-derived structural units in the VAE copolymer may be from 55 wt% to 95 wt%, but is not limited thereto. Optionally, the content of vinyl acetate-derived structural units in the VAE copolymer may be 55 wt%, 60 wt%, 65 wt%, 70 wt%, 75 wt%, 80 wt%, 85 wt%, 90 wt%, 95 wt%, or may be within a range consisting of any two of the above values.

[0014] In some embodiments, the dispersion matrix may comprise polyvinyl alcohol (PVA), hydroxyethyl cellulose (HEC), alkyl sulfates having 8 to 18 carbon atoms, alkyl sulfonates having 8 to 18 carbon atoms, alkyl aryl sulfonates having 8 to 18 carbon atoms, or combinations thereof. In other embodiments, the dispersion matrix may also be an alkyl sulfate having 8 to 18 hydrophobic groups and up to 40 ethylene oxide or propylene oxide units, an alkyl aryl ether sulfate having 8 to 18 hydrophobic groups and up to 40 ethylene oxide or propylene oxide units, an ester or half-ester of sulfosuccinic acid and a monohydric alcohol or alkylphenol, or combinations thereof, but is not limited thereto.

[0015] Preferably, the degree of saponification of polyvinyl alcohol is from 75 mol% to 99.5 mol%; more preferably, the degree of saponification of polyvinyl alcohol is from 80 mol% to 90 mol%. The aforementioned degree of saponification is measured according to the JIS K 6726 standard method. In addition, the average degree of polymerization of polyvinyl alcohol is from 200 to 2000.

[0016] In some embodiments, the content of the dispersion matrix, based on the weight of the water-redispersible composition, may be from 3 wt% to 15 wt%, but is not limited thereto. Optionally, the content of the dispersion matrix may be 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 11 wt%, 12 wt%, 13 wt%, 14 wt%, 15 wt%, or may be within a range consisting of any two of the above values.

[0017] In some embodiments, the content of the inorganic compound, based on the weight of the water-redispersible composition, may be from 2 wt% to 15 wt%, but is not limited thereto. Optionally, the content of the inorganic compound may be 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 11 wt%, 12 wt%, 13 wt%, 14 wt%, 15 wt%, or may be within a range consisting of any two of the above values.

[0018] In some embodiments, the inorganic compound may comprise polycrystalline silicates. In some embodiments, the inorganic compound may comprise aluminosilicates. Specifically, the aluminosilicates may comprise, but are not limited to: silicate minerals containing aluminum oxides, natural layered silicate minerals, clay minerals, mullite, anorthite, zeolite, bentonite, montmorillonite, nepheline, and albite.

[0019] In some embodiments, the water-redispersible composition may contain an anti-caking agent. Specifically, the anti-caking agent may comprise, but is not limited to, aluminum silicate, calcium carbonate, magnesium carbonate, dolomite, talc, silica, calcium sulfate, magnesium hydroxide, magnesium oxide, calcium phosphate, calcium silicate, or combinations thereof.

[0020] In some embodiments, the content of the anti-caking agent, based on the weight of the water-redispersible composition, may be from 5 wt% to 20 wt%, but is not limited thereto. Optionally, the content of the anti-caking agent may be 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 11 wt%, 12 wt%, 13 wt%, 14 wt%, 15 wt%, 16 wt%, 17 wt%, 18 wt%, 19 wt%, or 20 wt%, or may be within a range consisting of any two of the above values.

[0021] The method for preparing the water-redispersible composition of the present invention can employ preparation processes known to those skilled in the art, and is not particularly limited. Specifically, a dispersion can first be prepared by emulsion or suspension polymerization, wherein the dispersion is typically stabilized by a dispersion matrix (which can act as a stabilizer) on the VAE copolymer. Subsequently, the aforementioned dispersion can be dried by spray drying to obtain a solid concentrate; wherein, an additive (such as a spray adjuvant, but not limited thereto) or dispersion matrix may be added as appropriate to keep the solid concentrate in powder form. Next, the solid concentrate, the inorganic compound, and / or the anti-caking agent are mixed to obtain the water-redispersible composition.

[0022] The present invention also provides a cement composition comprising cement and the aforementioned water redispersible composition, wherein the cement composition has a adhesion strength degradation rate of less than 50% after immersion curing as defined in EN 12004-2:2017.

[0023] Preferably, the cement composition, after water curing as defined in EN 12004-2:2017, has a bond strength of 5.5 kgf / cm². 2 (The above, but not limited to this.)

[0024] In some embodiments, the cement may comprise silicate cement (also known as Portland cement), aluminate cement, sulfoaluminate cement, fluoroaluminate cement, or ferroaluminate cement. Alternatively, the cement may comprise white cement, black cement, or a combination thereof.

[0025] Preferably, the cement composition exhibits a 20-minute open-time adhesive strength greater than 5 kgf / cm² as defined in EN 12004-2:2017. 2 More preferably, the cement composition, after a 20-minute air-conditioning open time as defined in EN 12004-2:2017, exhibits a bond strength greater than or equal to 10 kgf / cm². 2 .

[0026] Preferably, the cement composition exhibits a 30-minute extended open time adhesive strength as defined in EN 12004-2:2017, which is greater than 5 kgf / cm². 2 More preferably, the cement composition, after an extended open time of 30 minutes of air exposure as defined in EN 12004-2:2017, exhibits a bond strength greater than or equal to 9 kgf / cm². 2 .

[0027] In some embodiments, the content of the water-redispersible composition may be from 1.0 wt% to 5.0 wt%, but is not limited thereto, based on the solid content of the cement composition. Optionally, the content of the water-redispersible composition may be 1.0 wt%, 1.5 wt%, 1.8 wt%, 2.0 wt%, 2.3 wt%, 2.5 wt%, 2.8 wt%, 3.0 wt%, 3.2 wt%, 3.5 wt%, 3.8 wt%, 4.0 wt%, 4.2 wt%, 4.5 wt%, 4.8 wt%, 5.0 wt%, or may be a range between any two of the above values.

[0028] In some embodiments, the cement content, based on the solid content of the cement composition, may be from 30 wt% to 50 wt%, but is not limited thereto. Optionally, the cement content may be 30 wt%, 32 wt%, 35 wt%, 38 wt%, 40 wt%, 42 wt%, 45 wt%, 48 wt%, 50 wt%, or a range between any two of the above values.

[0029] In some embodiments, the cement composition may also contain quartz sand, calcium carbonate, talc, calcium chloride, water-retaining agent, or a combination thereof.

[0030] Specifically, the average particle size of the quartz sand is from 109 micrometers (μm) to 270 μm. Optionally, based on the solid content of the cement composition, the content of the quartz sand can be from 50 wt% to 65 wt%. Optionally, the content of the quartz sand can be 50 wt%, 51 wt%, 52 wt%, 53 wt%, 54 wt%, 55 wt%, 56 wt%, 57 wt%, 58 wt%, 59 wt%, 60 wt%, 61 wt%, 62 wt%, 63 wt%, 64 wt%, 65 wt%, or a range between any two of the above values.

[0031] Specifically, the water-retaining agent may include cellulose ethers, modified starches, polyvinyl alcohols, natural gums, or synthetic polymers, but is not limited to these. Specifically, the cellulose ethers may include methylcellulose, hydroxypropyl methylcellulose (HPMC), etc., but are not limited to these; the natural gums may include guar gum, xanthan gum, etc., but are not limited to these. Optionally, based on the solid content of the cement composition, the content of the water-retaining agent may be from 0.1 wt% to 0.5 wt%.

[0032] In this specification, the range represented by "smallest value to largest value" means, unless otherwise specified, that the range is greater than or equal to the smallest value and less than or equal to the largest value. For example, the ratio of I1 / I2 is 0.9 to 1.0, which means that the numerical range of the ratio of I1 / I2 is "greater than or equal to 0.9 and less than or equal to 1.0".

[0033] Unless otherwise stated, the process conditions, values, or ranges contained herein are to be understood as being expressed in terms of the term "about". "About" may mean within ±5% of the stated values. Attached Figure Description

[0034] Figure 1 The image shows the wide-angle X-ray diffraction pattern of the water redispersible composition of Example 1 after combustion at 400°C for 40 minutes.

[0035] Figure 2 The wide-angle X-ray diffraction pattern of the water redispersible composition of Comparative Example 2 after combustion at 400°C for 40 minutes is shown. Detailed Implementation

[0036] The following examples illustrate the implementation of the water-redispersible composition and cement composition of the present invention, while providing several comparative examples for comparison. Those skilled in the art can easily understand the advantages and effects of the present invention through the following examples and comparative examples. It should be understood that the examples listed in this specification are merely illustrative of the implementation of the present invention and are not intended to limit the scope of the present invention. Those skilled in the art can make various modifications and alterations based on their ordinary knowledge without departing from the spirit of the present invention to implement or apply the content of the present invention.

[0037] Water-redispersible compositions

[0038] Example 1 (E1):

[0039] (1) Preparation of dispersion

[0040] First, 10 parts by weight of polyvinyl alcohol (with a saponification degree of 80 mol% to 90 mol%, an average degree of polymerization of 200 to 2000, and a Hoeppler viscosity of 4 mPa·s) are provided as a stabilizer. Next, 90 parts by weight of a VAE copolymer in emulsion form are prepared using an emulsion polymerization process known to those skilled in the art. The VAE copolymer contains 92 wt% vinyl acetate-derived structural units and 8 wt% ethylene-derived structural units, based on the total weight of the copolymer. Then, the VAE copolymer is uniformly dispersed in polyvinyl alcohol to obtain a stabilized dispersion.

[0041] (2) Preparation of powdered solid concentrate

[0042] First, 100 parts by weight of the dispersion and 15 parts by weight of polyvinyl alcohol are mixed to obtain a mixture. Then, the mixture is spray-dried into a powdered solid concentrate. Specifically, the mixture is atomized into microdroplets at 28,000 rpm using an atomizing disc, and then dried in a co-current flow under hot air at 130°C to obtain a powdered solid concentrate.

[0043] Finally, 100 parts by weight of the aforementioned solid concentrate, 7 parts by weight of the inorganic compound (polycrystalline aluminosilicate), and 10 parts by weight of the anti-caking agent (calcium carbonate) were mixed to obtain the water-redispersible composition of Example 1. Based on the weight of this water-redispersible composition, the content of the VAE copolymer was approximately 73.88 wt%, the content of polyvinyl alcohol was approximately 11.08 wt%, the content of the inorganic compound was approximately 5.95 wt%, and the content of the anti-caking agent was approximately 9.09 wt%.

[0044] Example 2 (E2):

[0045] (1) Preparation of dispersion

[0046] The dispersion used in this embodiment is the same as the dispersion used in Example 1.

[0047] (2) Preparation of powdered solid concentrate

[0048] First, 100 parts by weight of the dispersion and 15 parts by weight of polyvinyl alcohol are mixed to obtain a mixture. Then, the mixture is spray-dried into a powdered solid concentrate. Specifically, the mixture is atomized into microdroplets at 25,000 rpm using an atomizing disc, and then dried in a co-current flow under hot air at 135°C to obtain a powdered solid concentrate.

[0049] Finally, 100 parts by weight of the aforementioned solid concentrate, 3 parts by weight of the inorganic compound (polycrystalline aluminosilicate), and 16.5 parts by weight of the anti-caking agent (calcium carbonate) were mixed to obtain the water-redispersible composition of Example 2. Based on the weight of this water-redispersible composition, the content of the VAE copolymer was approximately 72.47 wt%, the content of polyvinyl alcohol was approximately 10.87 wt%, the content of the inorganic compound was approximately 2.5 wt%, and the content of the anti-caking agent was approximately 14.16 wt%.

[0050] Example 3 (E3):

[0051] (1) Preparation of dispersion

[0052] The dispersion used in this embodiment is the same as the dispersion used in Example 1.

[0053] (2) Preparation of powdered solid concentrate

[0054] First, 100 parts by weight of the dispersion and 15 parts by weight of polyvinyl alcohol are mixed to obtain a mixture. Then, the mixture is spray-dried into a powdered solid concentrate. Specifically, the mixture is atomized into microdroplets at 30,000 rpm using an atomizing disc, and then dried in a co-current flow under hot air at 133°C to obtain a powdered solid concentrate.

[0055] Finally, 100 parts by weight of the aforementioned solid concentrate, 5 parts by weight of the inorganic compound (polycrystalline aluminosilicate), and 13.5 parts by weight of the anti-caking agent (calcium carbonate) were mixed to obtain the water-redispersible composition of Example 3. Based on the weight of this water-redispersible composition, the content of the VAE copolymer was approximately 72.97 wt%, the content of polyvinyl alcohol was approximately 10.94 wt%, the content of the inorganic compound was approximately 4.2 wt%, and the content of the anti-caking agent was approximately 11.89 wt%.

[0056] Example 4 (E4):

[0057] (1) Preparation of dispersion

[0058] The dispersion used in this embodiment is the same as the dispersion used in Example 1.

[0059] (2) Preparation of powdered solid concentrate

[0060] First, 100 parts by weight of the dispersion and 15 parts by weight of polyvinyl alcohol are mixed to obtain a mixture. Then, the mixture is spray-dried into a powdered solid concentrate. Specifically, the mixture is atomized into microdroplets at 25,000 rpm using an atomizing disc, and then dried in a co-current flow under hot air at 127°C to obtain a powdered solid concentrate.

[0061] Finally, 100 parts by weight of the aforementioned solid concentrate, 7 parts by weight of the inorganic compound (polycrystalline aluminosilicate), and 10 parts by weight of the anti-caking agent (calcium carbonate) were mixed to obtain the water-redispersible composition of Example 4. Based on the weight of this water-redispersible composition, the content of the VAE copolymer was approximately 73.88 wt%, the content of polyvinyl alcohol was approximately 11.08 wt%, the content of the inorganic compound was approximately 5.95 wt%, and the content of the anti-caking agent was approximately 9.09 wt%.

[0062] Example 5 (E5):

[0063] (1) Preparation of dispersion

[0064] The dispersion used in this embodiment is the same as the dispersion used in Example 1.

[0065] (2) Preparation of powdered solid concentrate

[0066] First, 100 parts by weight of the dispersion and 15 parts by weight of polyvinyl alcohol are mixed to obtain a mixture. Then, the mixture is spray-dried into a powdered solid concentrate. Specifically, the mixture is atomized into microdroplets at 27,000 rpm using an atomizing disc, and then dried in a co-current flow under hot air at 133°C to obtain a powdered solid concentrate.

[0067] Finally, 100 parts by weight of the aforementioned solid concentrate and 13.5 parts by weight of the inorganic compound (polycrystalline aluminosilicate) were mixed to obtain the water-redispersible composition of Example 5. Based on the weight of this water-redispersible composition, the content of the VAE copolymer was approximately 76.61 wt%, the content of polyvinyl alcohol was approximately 11.49 wt%, and the content of the inorganic compound was approximately 11.9 wt%.

[0068] Example 6 (E6):

[0069] (1) Preparation of dispersion

[0070] The method for preparing the dispersion in this embodiment is similar to that in Example 1, with the main difference being that, in this embodiment, based on the total weight of the VAE copolymer, the content of the structural units derived from vinyl acetate in the VAE copolymer is 80 wt%, and the content of the structural units derived from ethylene is 20 wt%.

[0071] (2) Preparation of powdered solid concentrate

[0072] First, 100 parts by weight of the dispersion and 15 parts by weight of polyvinyl alcohol are mixed to obtain a mixture. Then, the mixture is spray-dried into a powdered solid concentrate. Specifically, the mixture is atomized into microdroplets at 27,000 rpm using an atomizing disc, and then dried in a co-current flow under hot air at 137°C to obtain a powdered solid concentrate.

[0073] Finally, 100 parts by weight of the aforementioned solid concentrate, 7 parts by weight of the inorganic compound (polycrystalline aluminosilicate), and 10 parts by weight of the anti-caking agent (calcium carbonate) were mixed to obtain the water-redispersible composition of Example 6. Based on the weight of this water-redispersible composition, the content of the VAE copolymer was approximately 73.88 wt%, the content of polyvinyl alcohol was approximately 11.08 wt%, the content of the inorganic compound was approximately 5.95 wt%, and the content of the anti-caking agent was approximately 9.09 wt%.

[0074] Example 7 (E7):

[0075] (1) Preparation of dispersion

[0076] The method for preparing the dispersion in this embodiment is similar to that in Example 1, with the main difference being that, in this embodiment, based on the total weight of the VAE copolymer, the content of the structural units derived from vinyl acetate in the VAE copolymer is 65 wt%, and the content of the structural units derived from ethylene is 35 wt%.

[0077] (2) Preparation of powdered solid concentrate

[0078] First, 100 parts by weight of the dispersion and 15 parts by weight of polyvinyl alcohol are mixed to obtain a mixture. Then, the mixture is spray-dried into a powdered solid concentrate. Specifically, the mixture is atomized into microdroplets at 28,000 rpm using an atomizing disc, and then dried in a co-current flow under hot air at 130°C to obtain a powdered solid concentrate.

[0079] Finally, 100 parts by weight of the aforementioned solid concentrate, 7 parts by weight of the inorganic compound (polycrystalline aluminosilicate), and 10 parts by weight of the anti-caking agent (calcium carbonate) were mixed to obtain the water-redispersible composition of Example 7. Based on the weight of this water-redispersible composition, the content of the VAE copolymer was approximately 73.88 wt%, the content of polyvinyl alcohol was approximately 11.08 wt%, the content of the inorganic compound was approximately 5.95 wt%, and the content of the anti-caking agent was approximately 9.09 wt%.

[0080] Comparative Example 1 (C1):

[0081] (1) Preparation of dispersion

[0082] The dispersion used in this comparative example is the same as the dispersion used in Example 1.

[0083] (2) Preparation of powdered solid concentrate

[0084] First, 100 parts by weight of the dispersion and 15 parts by weight of polyvinyl alcohol are mixed to obtain a mixture. Then, the mixture is spray-dried into a powdered solid concentrate. Specifically, the mixture is atomized into microdroplets at 26,500 rpm using an atomizing disc, and then dried in a co-current flow under hot air at 135°C to obtain a powdered solid concentrate.

[0085] Finally, 100 parts by weight of the aforementioned solid concentrate, 7 parts by weight of the inorganic compound (polycrystalline aluminosilicate), and 10 parts by weight of the anti-caking agent (calcium carbonate) were mixed to obtain the water-redispersible composition of Comparative Example 1. Based on the weight of this water-redispersible composition, the content of the VAE copolymer was approximately 73.88 wt%, the content of polyvinyl alcohol was approximately 11.08 wt%, the content of the inorganic compound was approximately 5.95 wt%, and the content of the anti-caking agent was approximately 9.09 wt%.

[0086] Comparative Example 2 (C2):

[0087] (1) Preparation of dispersion

[0088] The dispersion used in this comparative example is the same as the dispersion used in Example 1.

[0089] (2) Preparation of powdered solid concentrate

[0090] First, 100 parts by weight of the dispersion and 15 parts by weight of polyvinyl alcohol are mixed to obtain a mixture. Then, the mixture is spray-dried into a powdered solid concentrate. Specifically, the mixture is atomized into microdroplets at 28,000 rpm using an atomizing disc, and then dried in a co-current flow under hot air at 135°C to obtain a powdered solid concentrate.

[0091] Finally, 100 parts by weight of the aforementioned solid concentrate, 7 parts by weight of the inorganic compound (polycrystalline aluminosilicate), and 10 parts by weight of the anti-caking agent (calcium carbonate) were mixed to obtain the water-redispersible composition of Comparative Example 2. Based on the weight of this water-redispersible composition, the content of the VAE copolymer was approximately 73.88 wt%, the content of polyvinyl alcohol was approximately 11.08 wt%, the content of the inorganic compound was approximately 5.95 wt%, and the content of the anti-caking agent was approximately 9.09 wt%.

[0092] Comparative Example 3 (C3):

[0093] (1) Preparation of dispersion

[0094] The dispersion used in this comparative example is the same as the dispersion used in Example 1.

[0095] (2) Preparation of powdered solid concentrate

[0096] First, 100 parts by weight of the dispersion and 15 parts by weight of polyvinyl alcohol are mixed to obtain a mixture. Then, the mixture is spray-dried into a powdered solid concentrate. Specifically, the mixture is atomized into microdroplets at 27,000 rpm using an atomizing disc, and then dried in a co-current flow under hot air at 133°C to obtain a powdered solid concentrate.

[0097] Finally, 100 parts by weight of the aforementioned solid concentrate, 7 parts by weight of the inorganic compound (polycrystalline aluminosilicate), and 10 parts by weight of the anti-caking agent (calcium carbonate) were mixed to obtain the water-redispersible composition of Comparative Example 3. Based on the weight of this water-redispersible composition, the content of the VAE copolymer was approximately 73.88 wt%, the content of polyvinyl alcohol was approximately 11.08 wt%, the content of the inorganic compound was approximately 5.95 wt%, and the content of the anti-caking agent was approximately 9.09 wt%.

[0098] Experimental Example 1: Wide-angle X-ray Diffraction (WAXD)

[0099] This experimental example uses the water-redispersible compositions of Examples 1 to 7 and Comparative Examples 1 to 3 as the analytical objects. First, each water-redispersible composition was placed in a ceramic crucible and subjected to combustion at 400°C for 40 minutes. After being removed and cooled to room temperature, it was collected for later use. Next, 3 grams of each composition were taken from each group of experiments and uniformly placed on a circular stage. The stage was then compacted to fill the stage and form the test sample. The stage was then placed in an X-ray diffractometer (model: Aeris, manufactured by Malvern Panalytical). CuKα incident light with a wavelength of 1.54 Å was incident on the test sample, and constructive X-ray diffraction was observed on the crystal planes that satisfy Bragg's Law. Simultaneously, baseline correction was performed using HighScore analysis software, and a WAXD spectrum was obtained with 2θ as the horizontal axis and diffraction intensity (in arbitrary units (au)) as the vertical axis. Here, the scanning time is 12 minutes, the scanning rate is 0.1° / second, the scanning 2θ range is 5° to 80°, the laser voltage is 40 kV, and the laser current is 15 mA.

[0100] In each group's WAXD spectrum, a first characteristic peak with 2θ values ​​of 20.5° ≥ 2θ ≥ 20° and a second characteristic peak with 2θ values ​​of 20° > 2θ ≥ 19° were identified. Then, the signal intensity (I1) of the first characteristic peak and the signal intensity (I2) of the second characteristic peak were measured and recorded in Table 1. Furthermore, the I1 / I2 ratio for each group was calculated and also recorded in Table 1. In the groups of the embodiment, such as... Figure 1As shown, the WAXD map of Example 1 is representative.

[0101] Table 1. Signal intensity (I1), signal intensity (I2), and I1 / I2 ratio of the first characteristic peak of the water redispersible compositions of Examples 1 to 7 and Comparative Examples 1 to 3.

[0102]

[0103] Cement Compositions

[0104] Examples 1A to 7A

[0105] The water redispersible compositions of Examples 1 to 7 and Comparative Examples 1 to 3 were obtained respectively in the same manner as described below to obtain the cement compositions of Examples 1A to 7A and Comparative Examples 1A to 3A.

[0106] Specifically, each group of cement compositions contains 37.2 parts by weight of low-carbon silicate cement, 59.5 parts by weight of quartz sand (average particle size of 109 μm to 270 μm), 0.3 parts by weight of water-retaining agent, and 3 parts by weight of water-redispersible composition.

[0107] Test Example 2: Attachment Strength Test

[0108] This test used the cement compositions of Examples 1A to 7A and Comparative Examples 1A to 3A as the analysis objects. First, according to the European standard EN 12004-2:2017, 100 parts by weight of the cement composition and 24 to 26 parts by weight of water were mixed evenly to form a cement mortar at 23±2°C and 50±5% relative humidity. Then, the aforementioned cement mortar was applied to the floor tiles to form a coating with a thickness of approximately 5 to 7 mm. Next, the floor tiles coated with the aforementioned cement mortar were divided into four sections, and cured and subsequently tested under the following different conditions in sequence. The test results are recorded in Table 2:

[0109] (I) 28-day standard curing: Let stand for 28 days under standard conditions of 23±2℃ and relative humidity of 50±5%; after completion, use a tensile testing machine (manufactured by Hongda Company) to measure the adhesion strength of each group, which is the "28-day standard adhesion strength".

[0110] (II) After 7 days of standard curing (i.e., standing for 7 days under standard conditions of 23±2℃ and 50±5% relative humidity), a further 21 days of immersion curing is performed. After completion, the adhesion strength of each group is measured using the tensile testing machine described above, which is the "immersion adhesion strength". Furthermore, the adhesion strength degradation rate is calculated as: (28-day standard adhesion strength - immersion adhesion strength) / (28-day standard adhesion strength) * 100%.

[0111] (III) Under the environmental conditions of 23±2℃ and relative humidity of 50±5%, the cement mortar coating is left to air for 20 minutes before being covered with porous ceramic tiles, followed by 28 days of standard curing. After completion, the adhesion strength of each group is measured by the tensile testing machine mentioned above, which is the "open time adhesion strength after 20 minutes of air exposure" (Table 2, abbreviated as: open time adhesion strength).

[0112] (IV) Under environmental conditions of 23±2℃ and relative humidity of 50±5%, the cement mortar coating was left to air for 30 minutes before being covered with porous ceramic tiles, followed by 28 days of standard curing. After completion, the adhesion strength of each group was measured with the above tensile testing machine, which is the "extended open time adhesion strength after 30 minutes of air exposure" (Table 2, abbreviated as: extended open time adhesion strength).

[0113] Table 2 Adhesion strength of cement compositions of Examples 1A to 7A and Comparative Examples 1A to 3A (unit: kgf / cm) 2 Test results

[0114]

[0115] Discussion of Experimental Results

[0116] Based on the above experimental examples 1 and 2, it can be seen that, since the signal intensity of the first characteristic peak at 20.5°≧2θ≧20° is in a specific range (0.9 to 1.0) relative to the signal intensity of the second characteristic peak at 20°>2θ≧19° in the wide-angle X-ray diffraction pattern after the water redispersible compositions of Examples 1 to 7 have a specific crystal structure, that is, the first characteristic peak at 20.5°≧2θ≧20° corresponds to the (110) lattice plane, and the second characteristic peak at 20°>2θ≧19° corresponds to the (020) lattice plane, when applied to cement compositions, it can improve their water resistance, thereby improving the adhesion strength of the cement composition under immersion curing conditions and improving its degradation rate. Conversely, because the I1 / I2 ratio of the water-redispersible compositions of Comparative Examples 1 to 3 is outside the aforementioned range, when these compositions are applied to cement compositions, the degradation rate of their adhesion strength under immersion curing conditions is greater than 50%, and may even be as high as nearly 80%. As can be seen from the above comparative results, compared to Comparative Examples 1 to 3 and Comparative Examples 1A to 3A, the water-redispersible compositions of Examples 1 to 7 and the cement compositions of Examples 1A to 7A containing them do indeed have better water resistance, thus reducing the damage of water to the cured cement.

[0117] Furthermore, in both the "open time adhesion strength after 20 minutes of air exposure" and "extended open time adhesion strength after 30 minutes of air exposure" tests, the cement compositions of Examples 1A to 7A still exhibited an adhesion strength greater than 5 kgf / cm², demonstrating that the cement compositions containing the water redispersible composition of the present invention do indeed have good adhesion strength.

[0118] The above embodiments are merely examples for the purpose of illustration and are not intended to limit the scope of the patent application of this invention. All other changes, modifications, and alterations made without departing from the disclosure of this invention should be included within the scope of the patent application of this invention.

Claims

1. A water-redispersible composition, characterized in that, The water-redispersible composition comprises a vinyl acetate-ethylene copolymer, a dispersion matrix, and an inorganic compound; wherein, in the wide-angle X-ray diffraction pattern of the water-redispersible composition, the signal intensity of the first characteristic peak at 20.5° ≥ 2θ ≥ 20° is in the ratio of the signal intensity of the second characteristic peak at 20° > 2θ ≥ 19° to 0.9 to 1.0; wherein, the wide-angle X-ray diffraction pattern of the water-redispersible composition is obtained by measuring the water-redispersible composition using CuKα rays after it has been burned at 400°C for 40 minutes.

2. The water-redispersible composition as claimed in claim 1, characterized in that, The vinyl acetate-ethylene copolymer comprises structural units derived from vinyl acetate and structural units derived from ethylene, wherein the content of the structural units derived from vinyl acetate is higher than the content of the structural units derived from ethylene.

3. The water-redispersible composition as described in claim 2, characterized in that, In the vinyl acetate-ethylene copolymer, the content of the ethylene-derived structural units is from 5% to 45% by weight.

4. The water-redispersible composition according to claim 1, characterized in that, Based on the weight of the water-redispersible composition, the content of the inorganic compound is from 2% to 15% by weight.

5. The water-redispersible composition as claimed in claim 1, characterized in that, The water-redispersible composition contains an anti-caking agent; the anti-caking agent content is from 5% to 20% by weight, based on the weight of the water-redispersible composition.

6. The water-redispersible composition as claimed in claim 1, characterized in that, The dispersion matrix comprises polyvinyl alcohol, hydroxyethyl cellulose, alkyl sulfates having 8 to 18 carbon atoms, alkyl sulfonates having 8 to 18 carbon atoms, alkyl aryl sulfonates having 8 to 18 carbon atoms, or combinations thereof.

7. The water-redispersible composition according to claim 1, characterized in that, The inorganic compound comprises polycrystalline silicates.

8. The water-redispersible composition according to any one of claims 1 to 7, characterized in that, The inorganic compound is an aluminum silicate.

9. A cement composition, characterized in that, The composition comprises cement and a water-redispersible composition as described in any one of claims 1 to 8, wherein the cement composition has a adhesion strength degradation rate of less than 50% after immersion curing as defined in EN 12004-2:2017.

10. The cement composition according to claim 9, characterized in that, The cement composition, as defined in EN 12004-2:2017, has an open time of 20 minutes of air exposure followed by a strength greater than 5 kgf / cm².

11. The cement composition according to claim 9, characterized in that, The cement composition, as defined in EN 12004-2:2017, after an extended open time of 30 minutes of air exposure, has a strength greater than 5 kgf / cm².

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