阅读说明：本技术 一种提升瓷砖胶开放时间的改性淀粉醚的制备方法 (Preparation method of modified starch ether for improving opening time of tile glue ) 是由 滕鲲 赵明 李青华 李长胤 李茂丰 赵洪山 张开民 于 2019-10-28 设计创作，主要内容包括：本发明涉及建筑添加剂技术领域,尤其涉及一种提升瓷砖胶开放时间的改性淀粉醚的制备方法,包括(1)化学改性：将淀粉、碱化剂、醇和抑制剂混合,加入多种醚化剂,控制醚化反应温度10-90℃、反应时间2-20小时,进行化学改性,得醚化淀粉；(2)物理改性：将步骤(1)制得的醚化淀粉、增稠剂、缓凝剂和减水剂混合一定时间,进行物理改性。该制备方法制得的改性淀粉醚用于瓷砖粘结剂,能够大大提升瓷砖粘结性能,显著提升开放时间,是现有淀粉醚产品及方法所无法达到的。(The invention relates to the technical field of building additives, in particular to a preparation method of modified starch ether for improving the opening time of tile glue, which comprises the following steps of (1) chemically modifying: mixing starch, an alkalizer, alcohol and an inhibitor, adding various etherifying agents, controlling the etherification reaction temperature to be 10-90 ℃ and the reaction time to be 2-20 hours, and carrying out chemical modification to obtain etherified starch; (2) physical modification: and (2) mixing the etherified starch prepared in the step (1), a thickening agent, a retarder and a water reducing agent for a certain time, and carrying out physical modification. The modified starch ether prepared by the preparation method is used for the tile adhesive, can greatly improve the tile adhesive property, obviously improves the opening time, and is not achieved by the existing starch ether product and method.)

1. The preparation method of the modified starch ether for improving the opening time of the tile adhesive is characterized by comprising the following operation steps:

(1) chemical modification

Mixing starch, an alkalizer, alcohol and an inhibitor, adding various etherifying agents, controlling the etherification reaction temperature to be 10-90 ℃ and the reaction time to be 2-20 hours, and carrying out chemical modification to obtain etherified starch;

(2) physical modification

And (2) mixing the etherified starch prepared in the step (1), a thickening agent, a retarder and a water reducing agent for a certain time, and carrying out physical modification.

2. The preparation method of the modified starch ether for improving the tile glue opening time according to claim 1, wherein the etherification reaction temperature is 15-85 ℃ and the etherification reaction time is 4-12 hours.

3. The preparation method of the modified starch ether for improving the tile glue opening time according to claim 1, wherein the mass ratio of the starch, the alkali and the etherifying agent used in the etherification reaction is 1 (0.01-1.5) to (0.02-1.75); preferably, the mass ratio of the starch, the alkali and the etherifying agent used in the etherification reaction is 1 (0.01-1) to 0.02-1.2; the mass ratio of the starch and the inhibitor used in the etherification reaction is 1 (0.05-0.1); the mass ratio of the starch to the alcohol used in the etherification reaction is 1 (0.1-2), and preferably, the mass ratio of the starch to the alcohol is 1 (0.2-1).

4. The preparation method of the modified starch ether for improving the opening time of the tile glue according to claim 1, wherein the physical modification is that the etherified starch is added with a thickening agent, a retarder and a water reducing agent to be mixed and modified for 40-60 min.

5. The preparation method of the modified starch ether for improving the opening time of the tile glue according to claim 4, wherein the weight proportions of the starch ether, the thickener, the retarder and the water reducing agent are respectively 5-40%, 56-94%, 0.5-2% and 0.5-2%, preferably, the weight proportions of the starch ether, the thickener, the retarder and the water reducing agent are respectively 10-30%, 56-88%, 1.0-2.0% and 1.0-2.0%, more preferably, the weight proportions of the starch ether, the thickener, the retarder and the water reducing agent are respectively 20-30%, 56-78%, 1.0-2.0% and 1.0-2.0%.

6. The preparation method of the modified starch ether for improving the opening time of the tile glue according to claim 4, wherein the starch ether is one or more of a mono-starch ether, a di-starch ether and a tri-starch ether, and preferably is a di-starch ether and/or a tri-starch ether; the thickening agent is one or more of carboxymethyl cellulose, methyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl methyl cellulose and hydroxyethyl cellulose, preferably hydroxypropyl methyl cellulose and/or hydroxyethyl methyl cellulose; the retarder is one or more of sodium lignosulfonate, calcium saccharate and sodium citrate, and is preferably sodium lignosulfonate; the water reducing agent is one or more of naphthalene series, aliphatic series and polycarboxylic acid series powder water reducing agents, and preferably polycarboxylic acid series powder water reducing agents.

7. The preparation method of the modified starch ether for improving the opening time of the tile glue according to claim 1, wherein the starch is one or more of corn starch, tapioca starch, potato starch and wheat starch, preferably one or more of corn starch, tapioca starch and potato starch, and more preferably tapioca starch; the alkalifying agent is alkali metal hydroxide powder, preferably NaOH and/or KOH, more preferably NaOH; the alcohol is one or more of methanol, ethanol, isopropanol, n-butanol, tert-butanol, acetone and diethylene glycol, preferably ethanol and/or isopropanol, and more preferably ethanol; the inhibitor is an alkali metal salt, preferably Na₂SO₄And/or NaCl, more preferably Na₂SO₄(ii) a The etherifying agent is one or more of chloroacetic acid or sodium chloroacetate, methyl chloride, ethyl chloride, propylene oxide and ethylene oxide, and preferably one or more of chloroacetic acid, propylene oxide and ethylene oxide.

8. A modified starch ether obtainable by the process according to any one of claims 1 to 7.

9. Use of the modified starch ether of claim 8 in the preparation of tile glue.

10. Use according to claim 9, characterized in that the modified starch ether is used in an amount of 0.2-0.5%, preferably 0.3-0.5% by weight of the tile glue.

Technical Field

The invention relates to the technical field of building additives, in particular to a preparation method of modified starch ether for improving the opening time of tile glue.

Background

The ceramic tile is used as a decorative material, the market is wide, generally, after the ceramic tile glue is mixed with water, the adjustment construction can be carried out within a certain time, the ceramic tile glue is required to be incapable of being quickly solidified and have a long opening time, after the ceramic tile glue is attached to the ceramic tile, the ceramic tile glue is ideally adhered firmly and cannot fall off, and the requirement is provided for the tensile adhesion strength of the ceramic tile glue. Along with the continuous improvement of the specialization degree of the ceramic tile market, the ceramic tile with long open time is more and more required, the traditional ceramic tile adhesive is difficult to meet the requirements, and then the novel ceramic tile adhesive is rapidly developed.

The novel tile adhesive comprises cement, sand, heavy calcium carbonate, redispersible latex powder, cellulose ether, lignocellulose and the like. Patent CN107573539A describes a modified cellulose ether for increasing the open time of tile glue, the cellulose ether is used as a thickening water-retaining agent in the building field, and has a good effect for increasing the open time of tile glue, the starch ether used in modifying the cellulose ether is hydroxypropyl starch, usually, the cellulose ether and the starch ether are used as polysaccharide molecules, the more hydrophilic groups in the substituent groups are, the stronger the ability of retaining water is, thereby delaying the hydration speed of cement particles, making the tile glue not be able to be quickly coagulated, and having a longer open time, but the hydroxypropyl starch is used as starch ether with only one hydrophilic group, the hydrophilicity of the hydroxypropyl starch is poorer than that of modified starch ether with multiple hydrophilic groups, the synergistic effect after compounding the cellulose ether and single starch ether is limited to a certain extent, the water retention is also weaker, and only the basic requirement that the open time is more than or equal to 20min in JC/T547-2005 can be satisfied, it is difficult to meet the requirements of tile glue for higher open time.

Starch ether is a generic name of modified starch containing ether bonds in molecules, also called etherified starch, is starch substituent ether generated by reaction of hydroxyl in starch molecules and reactive substances, and comprises hydroxyalkyl starch, carboxymethyl starch, cationic starch and the like, and is widely applied to the industries of construction, medicine, food, textile, papermaking, daily chemical industry, petroleum and the like. In the building field, the starch ether can be used as an additive of cement-based products, gypsum-based products and calcium lime products, has good compatibility with other buildings and additives, and is particularly suitable for building dry mixes such as mortar, adhesives, plastering, rolling and the like. The starch ether with only one hydrophilic group is poorer in hydrophilicity than modified starch ether with multiple hydrophilic groups, so that the application of the starch ether is limited, and the index can not be generally achieved in the application of the starch ether sold in the market and the production of ceramic tile adhesives according to the requirement that the open time is more than or equal to 30min in the standard JC/T547-2005. Thus, it is thought that the structure and properties of the starch ether can be improved by a particular method, for example, by modifying the starch ether to meet the requirement of higher open time, without affecting the properties of the tile adhesive such as adhesion and without increasing the cost.

However, the preparation of the starch ether product by the existing method is mainly a multi-step etherification operation, is complex in operation, is not beneficial to industrial production, and generally only carries out chemical modification. With the increase of the requirement of the tile adhesive on the open time, the improvement of the method is needed to provide the modified starch ether with low cost and ultra-long open time.

Disclosure of Invention

The invention provides a preparation method of modified starch ether for improving the ceramic tile adhesive opening time, aiming at making up the defects of the prior art.

The invention is realized by the following technical scheme:

a preparation method of modified starch ether for improving the opening time of tile glue comprises the following operation steps:

(1) chemical modification

Mixing starch, an alkalizer, alcohol and an inhibitor, adding various etherifying agents, controlling the etherification reaction temperature to be 10-90 ℃ and the reaction time to be 2-20 hours, and carrying out chemical modification to obtain etherified starch;

(2) physical modification

And (2) mixing the etherified starch prepared in the step (1), a thickening agent, a retarder and a water reducing agent for a certain time, and carrying out physical modification.

The etherification reaction temperature is 15-85 ℃, and the etherification reaction time is 4-12 hours.

The etherification reaction comprises the steps of firstly cooling and reacting for a certain time, and then heating and reacting in sections.

The etherification reaction comprises the steps of firstly cooling to 10-20 ℃ for reaction for 1.5-2.5h, then heating to 35-50 ℃ for reaction for 2-3h, and continuously heating to 60-70 ℃ for reaction for 4-5 h.

The mass ratio of starch, alkali and etherifying agent used in the etherification reaction is 1 (0.01-1.5) to 0.02-1.75; preferably, the mass ratio of the starch, the alkali and the etherifying agent used in the etherification reaction is 1 (0.01-1) to 0.02-1.2; the mass ratio of the starch and the inhibitor used in the etherification reaction is 1 (0.05-0.1); the mass ratio of the starch to the alcohol used in the etherification reaction is 1 (0.1-2), and preferably, the mass ratio of the starch to the alcohol is 1 (0.2-1).

The physical modification is to add thickening agent, retarder and water reducing agent into etherified starch for mixing and modifying for 40-60 min.

The weight proportions of the starch ether, the thickening agent, the retarder and the water reducing agent are respectively 5-40%, 56-94%, 0.5-2% and 0.5-2%, preferably, the weight proportions of the starch ether, the thickening agent, the retarder and the water reducing agent are respectively 10-30%, 56-88%, 1.0-2.0% and 1.0-2.0%, and further preferably, the weight proportions of the starch ether, the thickening agent, the retarder and the water reducing agent are respectively 20-30%, 56-78%, 1.0-2.0% and 1.0-2.0%.

The starch ether is one or more of a monoastarch ether (with one substituent group, such as carboxymethyl starch, hydroxypropyl starch, hydroxyethyl starch and the like), a binary starch ether (with two substituent groups, such as carboxymethyl hydroxypropyl starch, hydroxypropyl hydroxyethyl starch, carboxymethyl hydroxyethyl starch and the like), a ternary starch ether (with three substituent groups, such as carboxymethyl hydroxypropyl hydroxyethyl starch, hydroxypropyl hydroxyethyl ethyl starch, hydroxypropyl hydroxyethyl methyl starch and the like), and is preferably one or two of a binary starch ether and a ternary starch ether; the thickening agent is one or more of carboxymethyl cellulose, methyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl methyl cellulose and hydroxyethyl cellulose, and preferably one or two of hydroxypropyl methyl cellulose and hydroxyethyl methyl cellulose; the retarder is one or more of sodium lignosulfonate, calcium saccharate and sodium citrate, and is preferably sodium lignosulfonate; the water reducing agent is one or more of naphthalene series, aliphatic series and polycarboxylic acid series powder water reducing agents, and preferably polycarboxylic acid series powder water reducing agents.

The starch is one or more of corn starch, tapioca starch, potato starch and wheat starch, preferably one or more of corn starch, tapioca starch and potato starch, and more preferably tapioca starch; the alkalifying agent is alkali metal hydroxide powder, preferably NaOH and/or KOH, more preferably NaOH; the alcohol is one or more of methanol, ethanol, isopropanol, n-butanol, tert-butanol, acetone and diethylene glycol, preferably ethanol and/or isopropanol, and more preferably ethanol; the inhibitor is an alkali metal salt, preferably Na₂SO₄And/or NaCl, more preferably Na₂SO₄(ii) a The etherifying agent is one or more of chloroacetic acid, sodium chloroacetate, methyl chloride, ethyl chloride, propylene oxide and ethylene oxide, and preferably one or more of chloroacetic acid, propylene oxide and ethylene oxide.

The modified starch ether prepared by the preparation method.

The modified starch ether is applied to the preparation of ceramic tile glue.

The modified starch ether accounts for 0.2-0.5%, preferably 0.3-0.5% of the weight of the tile adhesive.

The invention has the beneficial effects that:

compared with the prior art, the modified starch ether prepared by the preparation method provided by the invention is used for a ceramic tile binder, and can obviously prolong the opening time of a ceramic tile. According to the preparation method, raw material starch and various hydrophilic etherifying agents are chemically modified to obtain hydrophilic starch ether, proper mixing amounts of thickening agents, retarders and water reducing agents are added for physical mixing to obtain modified starch ether, the hydrophilic starch ether and the hydrophilic thickening agents are mixed to generate a synergistic effect to improve the water retention property of the modified starch ether, and hydrophilic retarders, namely sodium lignosulfonate and water reducing agent polycarboxylic acid powder are added to further improve the water retention property of the modified starch ether, so that the hydration speed of cement particles is delayed, tile glue cannot be rapidly condensed, the opening time of the tile glue is prolonged, and the strength and the bonding property of the tile glue are improved. According to the invention, water is not needed in the preparation process from the raw starch to the modified starch ether, the water in the raw starch is used as an alkali solvent, the least amount of alcohol solvent is used as an alkali dispersing agent, the use of a large amount of alcohol solvent and water in the preparation of the modified starch ether by the traditional method is avoided, the alcohol solvent and the etherifying agent after reaction are recycled in the drying process, the product is not needed to be washed and neutralized, the process for preparing the modified starch ether by the traditional method is greatly simplified, the process and the equipment are simple, the operation is easy, three wastes are not discharged, the environment is protected, the quality of the obtained modified starch ether product is stable, the function of improving the opening time of the ceramic tile adhesive is realized, the requirements of different consumption layers can be met.

Compared with the existing modification method, the preparation method has the advantages that the operation conditions are also obviously different, particularly the reaction temperature of chemical modification is generally more than 35 ℃, the method can be carried out at the temperature lower than 35 ℃, the earlier-stage lower reaction temperature treatment can ensure the sufficiency of material dispersion, the etherification efficiency and the reaction safety of a single etherifying agent are improved, the operation requirement is reduced, the preparation is simple, and resources and energy are saved.

Drawings

FIG. 1 is a process flow diagram of the present invention.

Detailed Description

In order to clearly explain the technical features of the present invention, the following detailed description of the present invention is provided with reference to the accompanying drawings.

The carboxymethyl substitution Degree (DS) of the starch ethers prepared in each example and comparative example was determined by the following method.

Will be fully washed without Cl^-After drying the existing starch ether sample, slowly heating in a muffle furnace, gradually heating to 700 ℃, burning for 1h to completely ash the sample, and quantitatively converting the sample into Na₂And O. The ashes were dissolved in a quantitative standard solution of sulfuric acid and the excess sulfuric acid was titrated with a standard solution of NaOH. The carboxymethyl substitution degree of the starch ether is calculated according to formula (1):

DS＝0.162B/(1-0.08B) (1)

in formula (1), B is the consumption of 1/2H per gram of sample₂SO₄The amount of mmol of (A) is calculated by the following formula (2):

B＝(C(1/2H₂SO₄)×V(1/2H₂SO₄)-C NaOH×V NaOH)/W (2)

in the above-mentioned formula (2),

C(1/2H₂SO₄): the molar concentration mol/L of the sulfuric acid used

V(1/2H₂SO₄): volume of sulfuric acid used mL

C, NaOH: the molar concentration mol/L of the sodium hydroxide used

V NaOH: volume of sodium hydroxide used mL

W: and (5) drying to obtain the starch ether sample with constant weight in mass g.

The methoxy content and the hydroxyalkoxy content of the starch ethers and cellulose ethers prepared in the respective examples and comparative examples were measured by quantitatively cleaving the substituted alkoxy and hydroxyalkoxy groups by hydroiodic acid under the catalysis of adipic acid and then by gas chromatography according to the experimental method of cellulose ether group content appendix D of JC/T2190-2013 cellulose ethers for construction Dry mortars.

The starch ether viscosity prepared in each example was a 5% aqueous solution viscosity measured at 20 ℃ with a model NDJ-1 viscometer, and the cellulose ether viscosity was a 2% aqueous solution viscosity measured at 20 ℃ with a model B RVT viscometer.