A paste-like adhesive for exterior walls in extremely cold climates and its preparation method

Abstract

This invention belongs to the field of adhesive technology. This invention provides a paste-like adhesive for exterior walls in extremely cold climates and its preparation method. The paste-like adhesive for exterior walls in extremely cold climates comprises, by weight, the following components: 35-37 parts polyacrylic acid emulsion, 14-16 parts quartz sand, 45-48 parts granulated blast furnace slag powder, 1.5-1.7 parts aluminum sulfate, 0.25-0.35 parts dispersant, and 2.5-3 parts methyl methacrylate-hydroxypropyl methylcellulose graft copolymer. This invention can effectively extend the construction window period, reducing the decrease in tensile bond strength of the prepared adhesive during construction.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of back adhesive, in particular relates to a paste-like back adhesive for outer wall in extremely cold climate and a preparation method thereof. BACKGROUND

[0002] As a new type of bonding material applied to the back of ceramic tiles, back adhesive can not only effectively improve the flexibility of the bonding material, but also improve the bonding performance with the cement mortar layer, effectively overcome the phenomena of hollowing, ceramic tile falling off, etc., and is favored by the market. In the prior art, granulated blast furnace slag powder is added to the ceramic tile back adhesive, which can improve the bonding tensile strength of the ceramic tile back adhesive, and the bonding tensile strength of the ceramic tile back adhesive increases with the increase of the granulated blast furnace slag powder content.

[0003] It is known that when the ceramic tile back adhesive is left for 10 min, the emulsion film is more easily diffused into the mortar layer before the emulsion film is formed, so that the tensile bonding strength is higher; and as the standing time continues to extend, the emulsion of the ceramic tile back adhesive begins to form a film, the ceramic tile back adhesive is difficult to penetrate into the bonding agent, which is not conducive to the generation of copolymer, and the tensile bonding strength grows relatively slowly. Therefore, in order to ensure that the tensile bonding strength of the ceramic tile back adhesive is excellent, the best time for construction is within 10 min.

[0004] However, in the actual construction process, general workers need to operate multiple ceramic tiles at the same time, and the operation time of 10 min is relatively short, that is, the construction window period is short, and once the standing time exceeds 10 min, the tensile bonding strength of the ceramic tile back adhesive will decrease obviously. SUMMARY

[0005] In view of the above problems, the present application provides a paste-like back adhesive for outer wall in extremely cold climate and a preparation method thereof, which can effectively prolong the construction window period and reduce the decrease of the tensile bonding strength of the prepared back adhesive during the construction process.

[0006] In order to achieve the above purpose, the present application provides a paste-like back adhesive for outer wall in extremely cold climate, which comprises the following components in parts by weight: polyacrylic emulsion 35-37 parts, quartz sand 14-16 parts, granulated blast furnace slag powder 45-48 parts, aluminum sulfate 1.5-1.7 parts, dispersing agent 0.25-0.35 parts, and methyl methacrylate-hydroxypropyl methyl cellulose graft copolymer 2.5-3 parts.

[0007] Further, the preparation method of the methyl methacrylate-hydroxypropyl methyl cellulose graft copolymer is as follows:

[0008] A1, 3g of hydroxypropyl methyl cellulose is added to a four-necked flask (with a stirrer and condensing device) containing 70-80mL of water, dissolved, then N2 is passed for 30min, and the temperature is adjusted to 55±2℃ under the protection of N2 to obtain a basic solution;

[0009] A2, to the base solution obtained in A1, sulfuric acid is added to adjust the pH to 4.8-5.2, then potassium permanganate is added, and methyl methacrylate and oxalic acid are added dropwise, after reaction, precipitation, filtration and drying, the product is obtained.

[0010] Further, the mass ratio of methyl methacrylate to hydroxypropyl methyl cellulose is (1.2-1.5):1.

[0011] Further, the mass of potassium permanganate is 0.4-0.6% of the mass of methyl methacrylate.

[0012] Further, the amount-of-substance ratio of potassium permanganate to oxalic acid is 1:2.

[0013] Further, the particle size of the aluminum sulfate is 200 mesh.

[0014] Further, the dispersant is BYK-193.

[0015] Further, the type of the granulated blast furnace slag powder is SS800, and the specific surface area is 800 m 2 / Kg.

[0016] In a second aspect, the present application provides a preparation method of the above-mentioned paste-like back adhesive for outer walls in extremely cold climates, comprising the following steps:

[0017] S1, mixing polyacrylic emulsion, dispersant and methyl methacrylate-hydroxypropyl methyl cellulose graft copolymer to obtain a premix;

[0018] S2, adding quartz sand, granulated blast furnace slag powder and aluminum sulfate to the premix obtained in S1 and mixing evenly to obtain the product.

[0019] Compared with the prior art, the present application has the following beneficial effects:

[0020] In the preparation process of the back adhesive, methyl methacrylate-hydroxypropyl methyl cellulose graft copolymer and aluminum sulfate are simultaneously introduced. On the one hand, the hydroxypropyl groups on the molecular chain of hydroxypropyl methyl cellulose provide strong hydrophilicity, while the methyl methacrylate graft segment has hydrophobicity; this amphiphilic structure forms a three-dimensional network structure at the initial stage of stirring, which encapsulates the aluminum sulfate ions, delays the diffusion rate of aluminum sulfate to the emulsion particles, and weakens the negative effects brought by aluminum sulfate alone.

[0021] On the other hand, the methyl methacrylate grafting segment is compatible with the polyacrylic emulsion by physical entanglement, and the ester group thereof forms a hydrogen bond with the carboxyl group on the surface of the emulsion particle, thereby enhancing the interfacial bonding force; meanwhile, the hydroxypropyl methyl cellulose is adsorbed on the surface of the slag by hydrogen bond, and the long chain thereof is wound to form steric hindrance, thereby inhibiting the particle sedimentation, and the hydrophobic end of the grafting segment is embedded in the emulsion film layer, thereby improving the interfacial bonding strength; the hydroxypropyl methyl cellulose molecule can be locally plastically deformed in the stress concentration area (such as the tip of the microcrack), thereby absorbing energy and triggering the secondary hydration of the slag, thereby prolonging the construction window period, that is, the decrease range of the tensile bonding strength of the tile back adhesive decreases with the increase of the standing time.

[0022] In addition, the three-dimensional network of the methyl methacrylate-hydroxypropyl methyl cellulose graft copolymer delays the diffusion rate of Al 3+ , makes Al(OH)3 more uniformly dispersed in the matrix, reduces local agglomeration, optimizes the pore filling effect, and cooperatively improves the tensile bonding strength of the tile back adhesive while prolonging the construction window period. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 A comparison trend chart of the tensile bonding strength data of the tile back adhesive prepared in different standing time for example 1 to example 3 and comparative example 1 to comparative example 3 in the test example 1 of the present application is shown in the figure. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the present application will be described below in a clear and complete manner. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application. The raw materials of the embodiments and comparative examples of the present application are all commercially available, except for special instructions.

[0025] Example 1: (1) Preparation of methyl methacrylate-hydroxypropyl methyl cellulose graft copolymer, the preparation method is as follows:

[0026] A1, 3g of hydroxypropyl methyl cellulose was added to a four-necked flask (with a stirrer and condensing device) containing 75mL of water, dissolved, then N2 was passed for 30min, and the temperature was adjusted to 55℃ under the protection of N2 to obtain a base solution.

[0027] A2, 0.02g of potassium permanganate was added to the base solution obtained in A1, and 4g of methyl methacrylate and 0.023g of oxalic acid were added dropwise, and after reaction, precipitation, filtration and drying were performed to obtain the product.

[0028] (2) A preparation method of a paste-like back adhesive for an external wall in extremely cold climate, comprising the following steps:

[0029] S1, by weight parts, polyacrylic acid emulsion 36 parts, dispersing agent 0.3 parts and methyl methacrylate-hydroxypropyl methyl cellulose graft copolymer 2.8 parts are mixed to obtain a premix.

[0030] S2, to the premix obtained in S1, add quartz sand 15 parts, granulated blast furnace slag powder 47 parts and aluminum sulfate 1.6 parts, mix evenly, namely.

[0031] Among them, the particle size of aluminum sulfate is 200 mesh. The dispersing agent is BYK-193. The type of granulated blast furnace slag powder is SS800, and the specific surface area is 800 m 2 / Kg.

[0032] Example 2: The difference between this embodiment and example 1 is that a preparation method of a paste-like back adhesive for an external wall in an extremely cold climate, comprising the following steps:

[0033] S1, by weight parts, polyacrylic acid emulsion 35 parts, dispersing agent 0.25 parts and methyl methacrylate-hydroxypropyl methyl cellulose graft copolymer 2.5 parts are mixed to obtain a premix.

[0034] S2, to the premix obtained in S1, add quartz sand 14 parts, granulated blast furnace slag powder 45 parts and aluminum sulfate 1.5 parts, mix evenly, namely.

[0035] Example 3: The difference between this embodiment and example 1 is that a preparation method of a paste-like back adhesive for an external wall in an extremely cold climate, comprising the following steps:

[0036] S1, by weight parts, polyacrylic acid emulsion 37 parts, dispersing agent 0.35 parts and methyl methacrylate-hydroxypropyl methyl cellulose graft copolymer 3 parts are mixed to obtain a premix.

[0037] S2, to the premix obtained in S1, add quartz sand 16 parts, granulated blast furnace slag powder 48 parts and aluminum sulfate 1.7 parts, mix evenly, namely.

[0038] Comparative example 1: The difference between this comparative example and example 1 is that in the preparation of a paste-like back adhesive for an external wall in an extremely cold climate, methyl methacrylate-hydroxypropyl methyl cellulose graft copolymer and aluminum sulfate are not added.

[0039] Specifically, a preparation method of a paste-like back adhesive for an external wall in an extremely cold climate, comprising the following steps:

[0040] S1, by weight parts, polyacrylic acid emulsion 36 parts and dispersing agent 0.3 parts are mixed to obtain a premix.

[0041] S2, to the premix obtained in S1, add quartz sand 15 parts and granulated blast furnace slag powder 47 parts, mix evenly, namely.

[0042] Comparative Example 2: The difference between this comparative example and Example 1 is that no methyl methacrylate-hydroxypropyl methylcellulose graft copolymer is added in the preparation of the exterior wall paste adhesive for extremely cold climates.

[0043] Specifically, a method for preparing a paste-like adhesive for exterior walls in extremely cold climates includes the following steps:

[0044] S1. Mix 36 parts by weight of polyacrylic acid emulsion and 0.3 parts by weight to obtain a premix.

[0045] S2. Add 15 parts of quartz sand, 47 parts of granulated blast furnace slag powder and 1.6 parts of aluminum sulfate to the premix obtained in S1, mix well, and the mixture is ready.

[0046] Comparative Example 3: The difference between this comparative example and Example 1 is that aluminum sulfate is not added in the preparation of the exterior wall paste adhesive for extremely cold climates.

[0047] Specifically, a method for preparing a paste-like adhesive for exterior walls in extremely cold climates includes the following steps:

[0048] S1. By weight, 36 parts of polyacrylic acid emulsion, 0.3 parts of dispersant and 2.8 parts of methyl methacrylate-hydroxypropyl methylcellulose graft copolymer are mixed to obtain a premix.

[0049] S2. Add 15 parts of quartz sand and 47 parts of granulated blast furnace slag powder to the premix obtained in S1, mix well, and the product is obtained.

[0050] Comparative Example 4: The difference between this comparative example and Example 1 is that in the preparation of the paste-like adhesive for exterior walls in extremely cold climates, granulated blast furnace slag powder is replaced with quartz sand.

[0051] Specifically, a method for preparing a paste-like adhesive for exterior walls in extremely cold climates includes the following steps:

[0052] S1. By weight, 36 parts of polyacrylic acid emulsion, 0.3 parts of dispersant and 2.8 parts of methyl methacrylate-hydroxypropyl methylcellulose graft copolymer are mixed to obtain a premix.

[0053] S2. Add 62 parts of quartz sand and 1.6 parts of aluminum sulfate to the premix obtained in S1, mix well, and the product is obtained.

[0054] Test Example 1: Test Subjects: Adhesives prepared in Examples 1-3 and Comparative Examples 1-3. Test Items and Methods: The tensile bond strength of the adhesives under different drying times was tested according to JC / T 547-2017; P1 type ceramic tiles were used. Test Results: See Table 1.

[0055] Table 1. Experimental data for Example 1

[0056]

[0057] Results Analysis: Combining the data in Table 1 and... Figure 1 Analysis was conducted on Example 1 and Comparative Examples 1-3, specifically comparing Comparative Examples 1 and 2. It was found that, compared to Comparative Example 1, the addition of aluminum sulfate in Comparative Example 2 resulted in a greater decrease in the tensile bond strength of the adhesive as the drying time increased. This indicates that simply adding aluminum sulfate can actually shorten the application window of the adhesive.

[0058] This is mainly because the Al produced by the dissociation of aluminum sulfate 3+ High-valence cations strongly adsorb onto the surface of polypropylene emulsion particles, significantly reducing the zeta potential and causing "instability and flocculation" in the emulsion system. At this point, the emulsion forms a film prematurely before fully penetrating the mortar pores, blocking subsequent mass exchange channels; SO4 2- As a strong acid radical, it further compresses the diffusion layer of emulsion particles, exacerbating the aggregation phenomenon; that is, adding aluminum sulfate alone will shorten the surface drying time of the emulsion, directly sacrificing the construction window period; thus, as the drying time increases, it will exacerbate the decrease in the tensile bonding strength of the tile backing adhesive.

[0059] Specifically, comparing Comparative Examples 1 and 3, it can be seen that, compared to Comparative Example 1, the addition of methyl methacrylate-hydroxypropyl methylcellulose graft copolymer in Comparative Example 3 resulted in a significantly smaller decrease in the tensile bond strength of the adhesive as the drying time increased. This indicates that the addition of methyl methacrylate-hydroxypropyl methylcellulose graft copolymer can extend the application window of the adhesive.

[0060] In comparison with Example 1, it can be seen that the simultaneous introduction of methyl methacrylate-hydroxypropyl methylcellulose graft copolymer and aluminum sulfate can produce a synergistic effect, which can synergistically reduce the decrease in tensile bond strength of the adhesive as the drying time increases, that is, synergistically extend the construction window period of the adhesive.

[0061] Test Example 2: Test Subjects: Adhesives prepared in Example 1 and Comparative Example 4. Test Items and Methods: The tensile bond strength and tensile bond strength after freeze-thaw cycles of the adhesive were tested according to JC / T547-2017, and the retention rate was calculated; Retention rate = Tensile bond strength after freeze-thaw cycles / Tensile bond strength × 100%. Test Results: See Table 2.

[0062] Table 2. Experimental data for Experiment Example 2

[0063]

[0064] Results Analysis: Based on the data in Table 2, the analysis of Example 1 and Comparative Example 4 shows that, compared with Comparative Example 4 which only used quartz sand, Example 1 replaced some of the quartz sand with granulated blast furnace slag powder. As a result, the tensile bond strength and retention rate of the adhesive after freeze-thaw cycles were significantly improved, making it more suitable for cold regions.

[0065] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A paste type back adhesive for an exterior wall in an extremely cold climate, characterized by comprising: a base material; a tackifier; a plasticizer; a filler; and a thickener. By weight parts, including the following components: polyacrylic acid emulsion 35-37 parts, quartz sand 14-16 parts, granulated blast furnace slag powder 45-48 parts, aluminum sulfate 1.5-1.7 parts, dispersant 0.25-0.35 parts and methyl methacrylate-hydroxypropyl methyl cellulose graft copolymer 2.5-3 parts.

2. The frost wall paste back adhesive of claim 1, wherein, The preparation method of the methyl methacrylate-hydroxypropyl methyl cellulose graft copolymer is as follows: A1, 3g of hydroxypropyl methyl cellulose is added to 70-80mL of water, dissolved, then N2 is passed, and the temperature is adjusted to 55±2℃, to obtain a base solution; A2, to the base solution obtained in A1, add sulfuric acid, adjust the pH to 4.8-5.2, then add potassium permanganate, drop methyl methacrylate and oxalic acid, after reaction, precipitate, filter, dry, and get.

3. The frost wall paste back adhesive of claim 2, wherein, The mass ratio of methyl methacrylate to hydroxypropyl methyl cellulose is (1.2-1.5):

1.

4. The subzero weather exterior wall paste back adhesive of claim 2, wherein, The mass of potassium permanganate is 0.4-0.6% of the mass of methyl methacrylate.

5. The subzero weather exterior wall paste back adhesive of claim 4, wherein, The amount-of-substance ratio of potassium permanganate to oxalic acid is 1:

2.

6. The subarctic exterior wall paste back adhesive of claim 1, wherein, The particle size of the aluminum sulfate is 200 mesh.

7. The subzero weather exterior wall paste back adhesive of claim 1, wherein, The dispersant is BYK-193.

8. The subzero weather exterior wall paste back adhesive of claim 1, wherein, The granulated blast furnace slag powder has a type of SS800, and a specific surface area of 800 m 2 / Kg.

9. A process for the preparation of a frost climate exterior wall paste adhesive according to any one of claims 1 to 8, characterized by, Including the following steps: S1, mix polyacrylic acid emulsion, dispersant and methyl methacrylate-hydroxypropyl methyl cellulose graft copolymer to obtain a premix; S2, add quartz sand, granulated blast furnace slag powder and aluminum sulfate to the premix obtained in S1, mix well, and get.

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