A preparation method of hydroxypropyl methylcellulose ether for interior wall neutral putty

Abstract

The present invention relates to a preparation method of hydroxypropyl methylcellulose ether for neutral putty for interior walls, and belongs to the technical field of cellulose ether building materials. The method comprises the following steps: mixing a hydrophilic modified graphene dispersion with a sodium polycarboxylate liquid dispersant; S2, spraying the liquid obtained by mixing the hydrophilic modified graphene dispersion with the sodium polycarboxylate liquid dispersant on the surface of the HPMC gel material after filter pressing in the HPMC granulation stage; granulating the gel material, crushing at low temperature, and obtaining a modified HPMC powder; and physically mixing the modified HPMC powder with a water reducer, pregelatinized corn starch, and polyethylene glycol through an air flow mixer according to a formula to obtain the hydroxypropyl methylcellulose ether for neutral putty for interior walls. The present invention effectively isolates the viscous material by relying on the material's own effect, improves the smoothness of the scraping process, and realizes efficient linear motion conversion, thereby improving the construction performance.

Description

Technical Field

[0001] The invention relates to a method for preparing hydroxypropyl methylcellulose ether for interior wall neutral putty, belonging to the technical field of cellulose ether building materials. Background Art

[0002] In the existing technology of interior wall putty, alkaline materials such as cement and lime are widely used. These materials are representatives of high energy consumption and high pollution. Environmental protection and low carbon are the general trend. In recent years, with the continuous advancement of building interior decoration retail and renovation projects, interior wall putty among auxiliary materials has attracted widespread attention. With the continuous change of market demand, environmentally friendly neutral products have developed rapidly relying on the environmentally friendly and low-carbon environment, and the market demand is also showing a trend of counter-trend growth. Therefore, it is very necessary to develop an environmentally friendly neutral interior wall putty.

[0003] Interior wall putty can be used for fine leveling of base wall surfaces, providing a good coating foundation for paint, and is an important part of the interior wall finishing system. However, during the winter construction cycle or low temperature conditions, there are problems such as long drying time of putty after construction, slow strength growth, and even ice formation of putty due to low winter temperatures. After the temperature rises, the material structure is damaged, resulting in a series of problems such as loss of bonding strength of the system, easy cracking and powdering, which seriously restricts the safety and weather resistance of winter construction and finishing systems. In response to such problems, the existing improvement plan is usually to add antifreeze additives, such as salts, ethylene glycol, propylene glycol, etc. The theoretical basis of such products is to appropriately extend the action time of the material and liquid water by lowering the freezing point. However, in actual operation, salts cannot solve the compatibility of additives with the raw material system, and have a negative impact on the growth of bonding strength; ethylene glycol and propylene glycol have high VOC environmental protection problems, which pose health risks to both construction and residential populations. At the same time, these additives cannot solve the problem of poor low-temperature film-forming properties of redispersible latex, and the material has problems such as cracking, powdering, and poor strength when used at low temperatures.

[0004] The Chinese invention patent with the authorization announcement number CN113336500B discloses a bonding mortar and its preparation method and application. The mortar includes component A and component B. Component A is a conventional component, including cement, cellulose ether and quartz sand, and component B includes modified acrylic emulsion and hydrophilic modified graphene dispersion; wherein the mass percentage of the hydrophilic group of graphene is 12~40%. The bonding mortar has excellent frost resistance and low-temperature film-forming properties, which can meet the normal construction requirements in a low temperature environment of -15~5℃, and has high bonding strength, excellent crack resistance and flexibility at both low and normal temperatures, which can solve the problems of winter construction and safety of exterior wall insulation systems.

[0005] However, bonding mortar is a thick coating material, and the thickness of a single-pass construction is usually greater than 5mm, and the amount of water retaining agent added is usually 0.2~0.3%, and the water demand is relatively low. Interior wall putty is a thin coating material, and the thickness of a single-pass construction is usually less than 2mm, and the amount of water retaining agent added is usually greater than 0.3%, and the water demand is relatively high. Due to different construction methods, if directly introduced, the original modified graphene dispersion will be affected by the increase in water consumption and the enhancement of water retention effect, thereby weakening the antifreeze effect, and the two-component product is not convenient enough in actual use; therefore, further changes to the formula are very necessary, and process improvements are also required to better integrate the liquid into the cellulose ether system. Summary of the invention

[0006] The present invention aims to solve the above problems, thereby providing a method for preparing hydroxypropyl methylcellulose ether for neutral putty for interior walls. The hydroxypropyl methylcellulose ether for neutral putty for interior walls prepared by the method of the present invention effectively isolates the viscous material by relying on the material's own effect, improves the smoothness of the scraping process, and realizes efficient linear motion conversion, thereby improving the construction performance; introduces modified graphene to change the existence form of free water and increase the low-temperature antifreeze performance of the material; introduces sodium polycarboxylate to improve the post-thickening and thinning effects of the product.

[0007] The technical solution of the present invention to solve the above problems is as follows:

[0008] A method for preparing hydroxypropyl methylcellulose ether for interior wall neutral putty comprises the following steps:

[0009] S1, mixing the hydrophilic modified graphene dispersion and the polycarboxylate sodium salt liquid dispersant to obtain a liquid modifier;

[0010] S2, when HPMC enters the granulation stage, the liquid modifier is sprayed evenly on the surface of the HPMC gel after filter pressing through a spray device, so that the liquid modifier and HPMC are evenly mixed to obtain a modified HPMC gel;

[0011] S3, granulating the modified HPMC gel material to prepare granular modified HPMC; performing low-temperature pulverization on the granular modified HPMC, controlling the pulverization temperature at 65-75° C., to obtain modified HPMC powder;

[0012] S4, physically mixing the modified HPMC powder with a water reducer, pregelatinized starch, and polyethylene glycol by an air flow mixer according to the formula to obtain the hydroxypropyl methylcellulose ether for the interior wall neutral putty;

[0013] The formula includes the following components in parts by weight:

[0014] Polyethylene glycol 5~10%,

[0015] A mixture of hydrophilic modified graphene dispersion and polycarboxylic acid sodium salt 1.5~2.0%,

[0016] Water reducing agent 1.5~3.0%,

[0017] Pregelatinized starch 1~3%,

[0018] The balance is hydroxypropyl methylcellulose ether.

[0019] As a preferred embodiment of the above technical solution, the molecular weight of the polyethylene glycol is 6000Da.

[0020] As a preferred embodiment of the above technical solution, the particle size fineness of the polyethylene glycol is not less than 180 μm.

[0021] As a preferred embodiment of the above technical solution, the hydrophilic modified graphene dispersion has a solid content of 4-8%, a hydroxyl mass content of 15-20%, and a carboxyl mass content of 4-8%.

[0022] As a preferred embodiment of the above technical solution, the polycarboxylate sodium salt is San Nopco's polycarboxylate sodium salt liquid dispersant SN-DISPERSANT 5040.

[0023] As a preferred embodiment of the above technical solution, the water reducer is composed of a polycarboxylic acid high-performance water reducer and a melamine high-efficiency water reducer in a mass ratio of (1-4):1.

[0024] As a preferred embodiment of the above technical solution, in step S2, the methoxy mass content of the HPMC is 27-30%, and the hydroxypropoxy mass content is 10-13%.

[0025] As a preferred embodiment of the above technical solution, in the mixture of the hydrophilic modified graphene and the sodium salt of polycarboxylate, the mass ratio of the hydrophilic modified graphene dispersion to the sodium salt of polycarboxylate is 1:1.

[0026] As a preferred embodiment of the above technical solution, the pregelatinized starch is high-amylose pregelatinized corn starch.

[0027] Starch can be divided into amylose and amylopectin according to its structure. In ordinary corn, the content of amylose is 22~27%; while in high-amylose corn, the content of amylose is more than 40%, and some even exceed 50%. In the above technical scheme of the present invention, high-amylose pregelatinized corn starch refers to the starch obtained by using high-amylose corn as raw material, preparing corn starch, and then undergoing pregelatinization treatment. More preferably, the content of amylose in the high-amylose pregelatinized corn starch is more than 75%.

[0028] As a preferred embodiment of the above technical solution, the polycarboxylic acid high performance water reducer is ZC-PC8310 produced by Zhaojia Technology.

[0029] As a preferred embodiment of the above technical solution, the melamine high-efficiency water reducer is SMF produced by Zhaojia Technology.

[0030] In summary, the present invention has the following beneficial effects:

[0031] 1. The present invention relies on the material's own effect to effectively isolate the sticky material, improve the smoothness of the scraping process, and achieve efficient linear motion conversion, thereby improving the construction performance;

[0032] 2. The present invention introduces new graphene raw materials, which are modified to change the existence form of free water, increase the low-temperature antifreeze performance of the material, and form a set of energy-saving, consumption-reducing, low-carbon and environmentally friendly ecological formula system through the reuse and modification innovation of tailings from other fields;

[0033] 3. The present invention utilizes the hydrophilic hydroxyl groups on the polyethylene glycol molecular chain to interact with water molecules to form hydrogen bonds, so that PEG has good water solubility and can retain moisture for a long time, which can maintain the stability and durability of the lubricating film layer, and plays a key role in the construction stability and durability of the product during operation; PEG molecules can form a continuous film between the contact surfaces, thereby reducing the friction effect, and PEG also has good dispersibility, which can evenly disperse solid particles in the liquid medium, reduce direct contact between particles, reduce friction, and thus improve construction performance;

[0034] 4. The present invention selects graphene raw materials with modified hydroxyl and carboxyl groups (hydroxyl group 15%-20%, carboxyl group 4%-8%) as antifreeze aids, which can better improve the binding rate with water molecules, so that liquid water exists in the form of bound water. At the same time, the free electrons in the hydroxyl and carboxyl groups form hydrogen bonds with water molecules, and then when the temperature drops below 0°C or even lower, the speed of water converting from liquid to solid will slow down; it can also be used in cement-based exterior wall systems to help cement materials hydrate at low temperatures and complete solidification and drying;

[0035] 5. The present invention uses the Nopco polycarboxylate sodium salt liquid dispersant SN-DISPERSANT 5040, which is beneficial to further enhance the stability of the graphene slurry, reduce the probability of agglomeration of the graphene slurry after drying, and improve the reduction degree of the graphene powder; in addition, the powder of the SN-DISPERSANT5040 dispersant after drying is more convenient to transport and use than the liquid form for modified cellulose ether, and has better dispersing and solubility properties than heavy calcium carbonate powder, which improves the problem of late thickening and thinning of putty. DETAILED DESCRIPTION

[0036] This specific implementation is only an explanation of the present invention, not a limitation of the present invention. Any changes made by those skilled in the art after reading the specification of the present invention will be protected by the patent law as long as they are within the scope of the claims.

[0037] Embodiment 1

[0038] A method for preparing hydroxypropyl methylcellulose ether for interior wall neutral putty comprises the following steps:

[0039] S1. Mixing a hydrophilic modified graphene dispersion and a sodium polycarboxylate liquid dispersant to obtain a liquid modifier; the hydrophilic modified graphene dispersion has a solid content of 5wt%, a hydroxyl mass content of 16.0%, and a carboxyl mass content of 7.0%; the sodium polycarboxylate is a sodium polycarboxylate liquid dispersant SN-DISPERSANT 5040 from San Nopco;

[0040] S2. After the alkalization, etherification and neutralization reactions are completed, when HPMC (methoxy mass content is 27.3%, hydroxypropoxy content is 10.5%) enters the granulation stage, the liquid modifier is sprayed evenly on the surface of the HPMC gel after filter pressing through a spray device, so that the liquid modifier and HPMC are evenly mixed to obtain a modified HPMC gel;

[0041] S3, granulating the modified HPMC gel material to prepare granular modified HPMC; performing low-temperature crushing on the granular modified HPMC, wherein the crushing temperature is controlled at about 70° C., and the actual operation is controlled at 65-75° C., to obtain modified HPMC powder;

[0042] S4. According to the formula, the modified HPMC powder is physically mixed with a water reducer, pregelatinized corn starch and polyethylene glycol by an air flow mixer to obtain the hydroxypropyl methylcellulose ether for the neutral putty for interior walls; the polyethylene glycol has a molecular weight of 6000Da and is sieved through a 100-mesh sieve; the pregelatinized corn starch is a high-amylose pregelatinized corn starch with a linear content of more than 75%;

[0043] The formula includes the following components in parts by weight:

[0044] Hydroxypropyl methylcellulose ether 85.0%,

[0045] Polyethylene glycol 10%,

[0046] Pregelatinized corn starch 2.0%,

[0047] 1.5% mixture of hydrophilic modified graphene dispersion and SN-DISPERSANT 5040,

[0048] Polycarboxylic acid high performance water reducer Zhaojia Technology ZC-PC8310 1.0%,

[0049] Melamine high efficiency water reducing agent Zhaojia Technology SMF 0.5%.

[0050] Embodiment 2

[0051] A method for preparing hydroxypropyl methylcellulose ether for interior wall neutral putty comprises the following steps:

[0052] S1. Mixing a hydrophilic modified graphene dispersion and a sodium polycarboxylate liquid dispersant to obtain a liquid modifier; the hydrophilic modified graphene dispersion has a solid content of 5wt%, a hydroxyl mass content of 16.0%, and a carboxyl mass content of 7.5%; the sodium polycarboxylate is a sodium polycarboxylate liquid dispersant SN-DISPERSANT 5040 produced by San Nopco;

[0053] S2. After the alkalization, etherification and neutralization reactions are completed, when HPMC (methoxy mass content is 28.1%, hydroxypropoxy content is 10.4%) enters the granulation stage, the liquid modifier is sprayed evenly on the surface of the HPMC gel after the filter press through a spray device, so that the liquid modifier and HPMC are evenly mixed to obtain a modified HPMC gel;

[0054] S3, granulating the modified HPMC gel material to prepare granular modified HPMC; performing low-temperature crushing on the granular modified HPMC, controlling the crushing temperature at about 70° C., and actually controlling the crushing temperature at 65-75° C., to obtain modified HPMC powder;

[0055] S4. According to the formula, the modified HPMC powder is physically mixed with a water reducer, pregelatinized corn starch and polyethylene glycol by an air flow mixer to obtain the hydroxypropyl methylcellulose ether for the neutral putty for interior walls; the polyethylene glycol has a molecular weight of 6000Da and is sieved through a 100-mesh sieve; the pregelatinized corn starch is a high-amylose pregelatinized corn starch with a linear content of more than 75%;

[0056] The formula includes the following components in parts by weight:

[0057] Hydroxypropyl methylcellulose ether 86.8%,

[0058] Polyethylene glycol 7.0%,

[0059] Pregelatinized corn starch 1.9%,

[0060] 1.7% mixture of hydrophilic modified graphene dispersion and SN-DISPERSANT 5040,

[0061] Polycarboxylic acid high performance water reducer Zhaojia Technology ZC-PC8310 1.8%,

[0062] Melamine high efficiency water reducing agent Zhaojia Technology SMF 0.8%.

[0063] Embodiment 3

[0064] A method for preparing hydroxypropyl methylcellulose ether for interior wall neutral putty comprises the following steps:

[0065] S1. Mixing a hydrophilic modified graphene dispersion and a sodium polycarboxylate liquid dispersant to obtain a liquid modifier; the hydrophilic modified graphene dispersion has a solid content of 5wt%, a hydroxyl mass content of 17.5%, and a carboxyl mass content of 8.0%; the sodium polycarboxylate is a sodium polycarboxylate liquid dispersant SN-DISPERSANT 5040 produced by San Nopco;

[0066] S2. After the alkalization, etherification and neutralization reactions are completed, when the HPMC (methoxy mass content is 29.6%, hydroxypropoxy content is 12.4%) enters the granulation stage, the liquid modifier is sprayed evenly on the surface of the HPMC gel after the filter press through a spray device, so that the liquid modifier and HPMC are evenly mixed to obtain a modified HPMC gel;

[0067] S3, granulating the modified HPMC gel material to prepare granular modified HPMC; performing low-temperature crushing on the granular modified HPMC, controlling the crushing temperature at about 70° C., and actually controlling the crushing temperature at 65-75° C., to obtain modified HPMC powder;

[0068] S4. According to the formula, the modified HPMC powder is physically mixed with a water reducer, pregelatinized corn starch and polyethylene glycol by an air flow mixer to obtain the hydroxypropyl methylcellulose ether for the neutral putty for interior walls; the polyethylene glycol has a molecular weight of 6000Da and is sieved through a 100-mesh sieve; the pregelatinized corn starch is a high-amylose pregelatinized corn starch with a linear content of more than 75%;

[0069] The formula includes the following components in parts by weight:

[0070] Hydroxypropyl methylcellulose ether 87.5%,

[0071] Polyethylene glycol 8.0%,

[0072] Pregelatinized corn starch 1.0%,

[0073] 1.6% mixture of hydrophilic modified graphene dispersion and SN-DISPERSANT 5040,

[0074] Polycarboxylic acid high performance water reducer Zhaojia Technology ZC-PC8310 1.2%,

[0075] Melamine high efficiency water reducing agent Zhaojia Technology SMF 0.7%.

[0076] Embodiment 4

[0077] A method for preparing hydroxypropyl methylcellulose ether for interior wall neutral putty comprises the following steps:

[0078] S1. Mixing a hydrophilic modified graphene dispersion and a sodium polycarboxylate liquid dispersant to obtain a liquid modifier; the hydrophilic modified graphene dispersion has a solid content of 5wt%, a hydroxyl mass content of 15.5%, and a carboxyl mass content of 8.0%; the sodium polycarboxylate is a sodium polycarboxylate liquid dispersant SN-DISPERSANT 5040 produced by San Nopco;

[0079] S2. After the alkalization, etherification and neutralization reactions are completed, when HPMC (methoxy mass content is 27.2%, hydroxypropoxy content is 11.3%) enters the granulation stage, the liquid modifier is sprayed evenly on the surface of the HPMC gel after filter pressing through a spray device, so that the liquid modifier and HPMC are evenly mixed to obtain a modified HPMC gel;

[0080] S3, granulating the modified HPMC gel material to prepare granular modified HPMC; performing low-temperature crushing on the granular modified HPMC, controlling the crushing temperature at about 70° C., and actually controlling the crushing temperature at 65-75° C., to obtain modified HPMC powder;

[0081] S4. According to the formula, the modified HPMC powder is physically mixed with a water reducer, pregelatinized corn starch and polyethylene glycol by an air flow mixer to obtain the hydroxypropyl methylcellulose ether for the neutral putty for interior walls; the polyethylene glycol has a molecular weight of 6000Da and is sieved through a 100-mesh sieve; the pregelatinized corn starch is a high-amylose pregelatinized corn starch with a linear content of more than 75%;

[0082] The formula includes the following components in parts by weight:

[0083] Hydroxypropyl methylcellulose ether 89.0%,

[0084] Polyethylene glycol 5.0%,

[0085] Pregelatinized corn starch 1.0%,

[0086] 2.0% mixture of hydrophilic modified graphene dispersion and SN-DISPERSANT 5040,

[0087] Polycarboxylic acid high performance water reducer Zhaojia Technology ZC-PC8310 2.0%,

[0088] Melamine high efficiency water reducing agent Zhaojia Technology SMF 1.0%.

[0089] Comparative Example 1

[0090] A method for preparing hydroxypropyl methylcellulose ether for interior wall neutral putty comprises the following steps:

[0091] S1. Mixing a hydrophilic modified graphene dispersion and a sodium polycarboxylate liquid dispersant to obtain a liquid modifier; the hydrophilic modified graphene dispersion has a solid content of 5wt%, a hydroxyl mass content of 16.0%, and a carboxyl mass content of 7.5%; the sodium polycarboxylate is a sodium polycarboxylate liquid dispersant SN-DISPERSANT 5040 produced by San Nopco;

[0092] S2. After the alkalization, etherification and neutralization reactions are completed, when HPMC (methoxy mass content is 28.1%, hydroxypropoxy content is 10.4%) enters the granulation stage, the liquid modifier is sprayed evenly on the surface of the HPMC gel after the filter press through a spray device, so that the liquid modifier and HPMC are evenly mixed to obtain a modified HPMC gel;

[0093] S3, granulating the modified HPMC gel material to prepare granular modified HPMC; performing low-temperature crushing on the granular modified HPMC, controlling the crushing temperature at about 70° C., and actually controlling the crushing temperature at 65-75° C., to obtain modified HPMC powder;

[0094] S4. According to the formula, the modified HPMC powder is physically mixed with a water reducer, pregelatinized corn starch and polyethylene glycol by an air flow mixer to obtain the hydroxypropyl methylcellulose ether for the neutral putty for interior walls; the polyethylene glycol has a molecular weight of 6000Da and is sieved through a 100-mesh sieve; the pregelatinized corn starch is a high-amylose pregelatinized corn starch with a linear content of more than 75%;

[0095] The formula includes the following components in parts by weight:

[0096] Hydroxypropyl methylcellulose ether 81.0%,

[0097] Polyethylene glycol 13.0%,

[0098] Pregelatinized corn starch 0.3%,

[0099] 2.5% mixture of hydrophilic modified graphene dispersion and SN-DISPERSANT 5040,

[0100] Polycarboxylic acid high performance water reducer Zhaojia Technology ZC-PC8310 3.0%,

[0101] Melamine high efficiency water reducing agent Zhaojia Technology SMF 0.2%.

[0102] Comparative Example 2

[0103] A method for preparing hydroxypropyl methylcellulose ether for interior wall neutral putty comprises the following steps:

[0104] S1. Mixing a hydrophilic modified graphene dispersion and a sodium polycarboxylate liquid dispersant to obtain a liquid modifier; the hydrophilic modified graphene dispersion has a solid content of 5wt%, a hydroxyl mass content of 16.0%, and a carboxyl mass content of 7.5%; the sodium polycarboxylate is a sodium polycarboxylate liquid dispersant SN-DISPERSANT 5040 produced by San Nopco;

[0105] S2. After the alkalization, etherification and neutralization reactions are completed, when HPMC (methoxy mass content is 28.1%, hydroxypropoxy content is 10.4%) enters the granulation stage, the liquid modifier is sprayed evenly on the surface of the HPMC gel after the filter press through a spray device, so that the liquid modifier and HPMC are evenly mixed to obtain a modified HPMC gel;

[0106] S3, granulating the modified HPMC gel material to prepare granular modified HPMC; performing low-temperature crushing on the granular modified HPMC, controlling the crushing temperature at about 70° C., and actually controlling the crushing temperature at 65-75° C., to obtain modified HPMC powder;

[0107] S4. According to the formula, the modified HPMC powder is physically mixed with a water reducer, pregelatinized corn starch and polyethylene glycol by an air flow mixer to obtain the hydroxypropyl methylcellulose ether for the neutral putty for interior walls; the polyethylene glycol has a molecular weight of 6000Da and is sieved through a 100-mesh sieve; the pregelatinized corn starch is a high-amylose pregelatinized corn starch with a linear content of more than 75%;

[0108] The formula includes the following components in parts by weight:

[0109] Hydroxypropyl methylcellulose ether 93.0%,

[0110] Polyethylene glycol 2.0%,

[0111] Pregelatinized corn starch 4.4%,

[0112] 0.2% mixture of hydrophilic modified graphene dispersion and SN-DISPERSANT 5040,

[0113] Polycarboxylic acid high performance water reducer Zhaojia Technology ZC-PC8310 0.3%,

[0114] Melamine high efficiency water reducing agent Zhaojia Technology SMF 0.1%.

[0115] Comparative Example 3

[0116] A method for preparing hydroxypropyl methylcellulose ether for interior wall neutral putty comprises the following steps:

[0117] S1. Mixing a hydrophilic modified graphene dispersion and a sodium polycarboxylate liquid dispersant to obtain a liquid modifier; the hydrophilic modified graphene dispersion has a solid content of 5wt%, a hydroxyl mass content of 16.0%, and a carboxyl mass content of 7.5%; the sodium polycarboxylate is a sodium polycarboxylate liquid dispersant SN-DISPERSANT 5040 produced by San Nopco;

[0118] S2. After the alkalization, etherification and neutralization reactions are completed, when HPMC (methoxy mass content is 28.1%, hydroxypropoxy content is 10.4%) enters the granulation stage, the liquid modifier is sprayed evenly on the surface of the HPMC gel after the filter press through a spray device, so that the liquid modifier and HPMC are evenly mixed to obtain a modified HPMC gel;

[0119] S3, granulating the modified HPMC gel material to prepare granular modified HPMC; performing low-temperature crushing on the granular modified HPMC, controlling the crushing temperature at about 70° C., and actually controlling the crushing temperature at 65-75° C., to obtain modified HPMC powder;

[0120] S4. According to the formula, the modified HPMC powder, the water reducing agent and the pregelatinized corn starch are physically mixed by an air flow mixer to obtain the hydroxypropyl methylcellulose ether for the neutral putty for interior walls; the pregelatinized corn starch is a high-amylose pregelatinized corn starch with an amylose content of more than 75%;

[0121] The formula includes the following components in parts by weight:

[0122] Hydroxypropyl methylcellulose ether 89.0%,

[0123] Pregelatinized corn starch 6.0%,

[0124] 2.0% mixture of hydrophilic modified graphene dispersion and SN-DISPERSANT 5040,

[0125] Polycarboxylic acid high performance water reducer Zhaojia Technology ZC-PC8310 2.0%,

[0126] Melamine high efficiency water reducing agent Zhaojia Technology SMF 1.0%.

[0127] Comparative Example 4

[0128] A method for preparing hydroxypropyl methylcellulose ether for interior wall neutral putty comprises the following steps:

[0129] S1. In the granulation stage of HPMC, the HPMC gel material is granulated to obtain granular HPMC; the granular HPMC is pulverized at low temperature, the pulverization temperature is controlled at about 70°C, and the actual operation is controlled at 65-75°C to obtain HPMC powder;

[0130] S2. According to the formula, HPMC powder is physically mixed with a water reducer, pregelatinized corn starch and polyethylene glycol by an air flow mixer to obtain the hydroxypropyl methylcellulose ether for neutral putty for interior walls; the polyethylene glycol has a molecular weight of 6000Da and is sieved through a 100-mesh sieve; the pregelatinized corn starch is a high-amylose pregelatinized corn starch with a linear content of more than 75%;

[0131] The formula includes the following components in parts by weight:

[0132] Hydroxypropyl methylcellulose ether 89.0%,

[0133] Polyethylene glycol 7.0%,

[0134] Pregelatinized corn starch 2.0%,

[0135] Polycarboxylic acid high performance water reducer Zhaojia Technology ZC-PC8310 1.0%,

[0136] Melamine high efficiency water reducing agent Zhaojia Technology SMF 1.0%.

[0137] Comparative Example 5

[0138] A method for preparing hydroxypropyl methylcellulose ether for interior wall neutral putty comprises the following steps:

[0139] S1. Mixing a hydrophilic modified graphene dispersion and a sodium polycarboxylate liquid dispersant to obtain a liquid modifier; the hydrophilic modified graphene dispersion has a solid content of 5wt%, a hydroxyl mass content of 10.0%, and a carboxyl mass content of 3.0%; the sodium polycarboxylate is a sodium polycarboxylate liquid dispersant SN-DISPERSANT 5040 from San Nopco;

[0140] S2. After the alkalization, etherification and neutralization reactions are completed, when HPMC (methoxy mass content is 28.1%, hydroxypropoxy content is 10.4%) enters the granulation stage, the liquid modifier is sprayed evenly on the surface of the HPMC gel after the filter press through a spray device, so that the liquid modifier and HPMC are evenly mixed to obtain a modified HPMC gel;

[0141] S3, granulating the modified HPMC gel material to prepare granular modified HPMC; performing low-temperature crushing on the granular modified HPMC, controlling the crushing temperature at about 70° C., and actually controlling the crushing temperature at 65-75° C., to obtain modified HPMC powder;

[0142] S4. According to the formula, the modified HPMC powder is physically mixed with a water reducer, pregelatinized corn starch and polyethylene glycol by an air flow mixer to obtain the hydroxypropyl methylcellulose ether for the neutral putty for interior walls; the polyethylene glycol has a molecular weight of 6000Da and is sieved through a 100-mesh sieve; the pregelatinized corn starch is a high-amylose pregelatinized corn starch with a linear content of more than 75%;

[0143] The formula includes the following components in parts by weight:

[0144] Hydroxypropyl methylcellulose ether 85.0%,

[0145] Polyethylene glycol 9.0%,

[0146] Pregelatinized corn starch 3.0%,

[0147] 1.5% mixture of hydrophilic modified graphene dispersion and SN-DISPERSANT 5040,

[0148] Polycarboxylic acid high performance water reducer Zhaojia Technology ZC-PC8310 1.0%,

[0149] Melamine high efficiency water reducing agent Zhaojia Technology SMF 0.5%.

[0150] Comparative Example 6

[0151] A method for preparing hydroxypropyl methylcellulose ether for interior wall neutral putty comprises the following steps:

[0152] S1. Mixing a hydrophilic modified graphene dispersion and a sodium polycarboxylate liquid dispersant to obtain a liquid modifier; the hydrophilic modified graphene dispersion has a solid content of 5wt%, a hydroxyl mass content of 25.0%, and a carboxyl mass content of 9.0%; the sodium polycarboxylate is a sodium polycarboxylate liquid dispersant SN-DISPERSANT 5040 produced by San Nopco;

[0153] S2. After the alkalization, etherification and neutralization reactions are completed, when HPMC (methoxy mass content is 28.1%, hydroxypropoxy content is 10.4%) enters the granulation stage, the liquid modifier is sprayed evenly on the surface of the HPMC gel after the filter press through a spray device, so that the liquid modifier and HPMC are evenly mixed to obtain a modified HPMC gel;

[0154] S3, granulating the modified HPMC gel material to prepare granular modified HPMC; performing low-temperature crushing on the granular modified HPMC, controlling the crushing temperature at about 70° C., and actually controlling the crushing temperature at 65-75° C., to obtain modified HPMC powder;

[0155] S4. According to the formula, the modified HPMC powder is physically mixed with a water reducer, pregelatinized corn starch and polyethylene glycol by an air flow mixer to obtain the hydroxypropyl methylcellulose ether for the neutral putty for interior walls; the polyethylene glycol has a molecular weight of 6000Da and is sieved through a 100-mesh sieve; the pregelatinized corn starch is a high-amylose pregelatinized corn starch with a linear content of more than 75%;

[0156] The formula includes the following components in parts by weight:

[0157] Hydroxypropyl methylcellulose ether 85.0%,

[0158] Polyethylene glycol 9.0%,

[0159] Pregelatinized corn starch 3.0%,

[0160] 1.5% mixture of hydrophilic modified graphene dispersion and SN-DISPERSANT 5040,

[0161] Polycarboxylic acid high performance water reducer Zhaojia Technology ZC-PC8310 1.0%,

[0162] Melamine high efficiency water reducing agent Zhaojia Technology SMF 0.5%.

[0163] Comparative Example 7

[0164] A method for preparing hydroxypropyl methylcellulose ether for interior wall neutral putty comprises the following steps:

[0165] S1. Mixing a hydrophilic modified graphene dispersion and a sodium polycarboxylate liquid dispersant to obtain a liquid modifier; the hydrophilic modified graphene dispersion has a solid content of 5wt%, a hydroxyl mass content of 25.0%, and a carboxyl mass content of 9.0%; the sodium polycarboxylate is a sodium polycarboxylate liquid dispersant SN-DISPERSANT 5040 produced by San Nopco;

[0166] S2. After the alkalization, etherification and neutralization reactions are completed, when HPMC (methoxy mass content is 28.1%, hydroxypropoxy content is 10.4%) enters the granulation stage, the liquid modifier is sprayed evenly on the surface of the HPMC gel after the filter press through a spray device, so that the liquid modifier and HPMC are evenly mixed to obtain a modified HPMC gel;

[0167] S3, granulating the modified HPMC gel material to prepare granular modified HPMC; performing low-temperature crushing on the granular modified HPMC, controlling the crushing temperature at about 70° C., and actually controlling the crushing temperature at 65-75° C., to obtain modified HPMC powder;

[0168] S4. According to the formula, the modified HPMC powder is physically mixed with a water reducer, pregelatinized corn starch and polyethylene glycol by an air flow mixer to obtain the hydroxypropyl methylcellulose ether for the neutral putty for interior walls; the polyethylene glycol has a molecular weight of 20,000 Da and is sieved through a 100-mesh sieve; the pregelatinized corn starch is a high-amylose pregelatinized corn starch with an amylose content of more than 75%;

[0169] The formula includes the following components in parts by weight:

[0170] Hydroxypropyl methylcellulose ether 85.0%,

[0171] Polyethylene glycol 9.0%,

[0172] Pregelatinized corn starch 3.0%,

[0173] 1.5% mixture of hydrophilic modified graphene dispersion and SN-DISPERSANT 5040,

[0174] Polycarboxylic acid high performance water reducer Zhaojia Technology ZC-PC8310 1.0%,

[0175] Melamine high efficiency water reducing agent Zhaojia Technology SMF 0.5%.

[0176] Comparative Example 8

[0177] A method for preparing hydroxypropyl methylcellulose ether for interior wall neutral putty comprises the following steps:

[0178] S1. Mixing a hydrophilic modified graphene dispersion and a sodium polycarboxylate liquid dispersant to obtain a liquid modifier; the hydrophilic modified graphene dispersion has a solid content of 5wt%, a hydroxyl mass content of 25.0%, and a carboxyl mass content of 9.0%; the sodium polycarboxylate is a sodium polycarboxylate liquid dispersant SN-DISPERSANT 5040 produced by San Nopco;

[0179] S2. After the alkalization, etherification and neutralization reactions are completed, when HPMC (methoxy mass content is 28.1%, hydroxypropoxy content is 10.4%) enters the granulation stage, the liquid modifier is sprayed evenly on the surface of the HPMC gel after the filter press through a spray device, so that the liquid modifier and HPMC are evenly mixed to obtain a modified HPMC gel;

[0180] S3, granulating the modified HPMC gel material to prepare granular modified HPMC; performing low-temperature crushing on the granular modified HPMC, controlling the crushing temperature at about 70° C., and actually controlling the crushing temperature at 65-75° C., to obtain modified HPMC powder;

[0181] S4. According to the formula, the modified HPMC powder is physically mixed with a water reducer, corn pregelatinized starch, and polyethylene glycol by an air flow mixer to obtain the hydroxypropyl methylcellulose ether for the neutral putty for interior walls; the polyethylene glycol has a molecular weight of 400Da and is sieved through a 100-mesh sieve; the corn pregelatinized starch is a high-amylose corn pregelatinized starch with an amylose content of more than 75%;

[0182] The formula includes the following components in parts by weight:

[0183] Hydroxypropyl methylcellulose ether 85.0%,

[0184] Polyethylene glycol 9.0%,

[0185] Pregelatinized corn starch 3.0%,

[0186] 1.5% mixture of hydrophilic modified graphene dispersion and SN-DISPERSANT 5040,

[0187] Polycarboxylic acid high performance water reducer Zhaojia Technology ZC-PC8310 1.0%,

[0188] Melamine high efficiency water reducing agent Zhaojia Technology SMF 0.5%.

[0189] Comparative Example 9

[0190] A method for preparing hydroxypropyl methylcellulose ether for interior wall neutral putty comprises the following steps:

[0191] S1. Mixing a hydrophilic modified graphene dispersion and a sodium polycarboxylate liquid dispersant to obtain a liquid modifier; the hydrophilic modified graphene dispersion has a solid content of 5wt%, a hydroxyl mass content of 16.0%, and a carboxyl mass content of 7.5%; the sodium polycarboxylate is a sodium polycarboxylate liquid dispersant SN-DISPERSANT 5040 produced by San Nopco;

[0192] S2. After the alkalization, etherification and neutralization reactions are completed, when HPMC (methoxy mass content is 18.3%, hydroxypropoxy content is 15.6%) enters the granulation stage, the liquid modifier is sprayed evenly on the surface of the HPMC gel after the filter press through a spray device, so that the liquid modifier and HPMC are evenly mixed to obtain a modified HPMC gel;

[0193] S3, granulating the modified HPMC gel material to prepare granular modified HPMC; performing low-temperature crushing on the granular modified HPMC, controlling the crushing temperature at about 70° C., and actually controlling the crushing temperature at 65-75° C., to obtain modified HPMC powder;

[0194] S4. According to the formula, the modified HPMC powder is physically mixed with a water reducer, pregelatinized corn starch and polyethylene glycol by an air flow mixer to obtain the hydroxypropyl methylcellulose ether for the neutral putty for interior walls; the polyethylene glycol has a molecular weight of 6000Da and is sieved through a 100-mesh sieve; the pregelatinized corn starch is a high-amylose pregelatinized corn starch with a linear content of more than 75%;

[0195] The formula includes the following components in parts by weight:

[0196] Hydroxypropyl methylcellulose ether 85.0%,

[0197] Polyethylene glycol 9.0%,

[0198] Pregelatinized corn starch 3.0%,

[0199] 1.5% mixture of hydrophilic modified graphene dispersion and SN-DISPERSANT 5040,

[0200] Polycarboxylic acid high performance water reducer Zhaojia Technology ZC-PC8310 1.0%,

[0201] Melamine high efficiency water reducing agent Zhaojia Technology SMF 0.5%.

[0202] Comparative Example 10

[0203] A method for preparing hydroxypropyl methylcellulose ether for interior wall neutral putty comprises the following steps:

[0204] S1. Mixing a hydrophilic modified graphene dispersion and a sodium polycarboxylate liquid dispersant to obtain a liquid modifier; the hydrophilic modified graphene dispersion has a solid content of 5wt%, a hydroxyl mass content of 16.0%, and a carboxyl mass content of 7.0%; the sodium polycarboxylate is a sodium polycarboxylate liquid dispersant SN-DISPERSANT 5040 from San Nopco;

[0205] S2. After the alkalization, etherification and neutralization reactions are completed, when HPMC (methoxy mass content is 27.3%, hydroxypropoxy content is 10.5%) enters the granulation stage, the liquid modifier is sprayed evenly on the surface of the HPMC gel after filter pressing through a spray device, so that the liquid modifier and HPMC are evenly mixed to obtain a modified HPMC gel;

[0206] S3, granulating the modified HPMC gel material to prepare granular modified HPMC; performing low-temperature crushing on the granular modified HPMC, controlling the crushing temperature at about 80° C., and actually controlling the crushing temperature at 75-85° C., to obtain modified HPMC powder;

[0207] S4. According to the formula, the modified HPMC powder is physically mixed with a water reducer, pregelatinized corn starch and polyethylene glycol by an air flow mixer to obtain the hydroxypropyl methylcellulose ether for the neutral putty for interior walls; the polyethylene glycol has a molecular weight of 6000Da and is sieved through a 100-mesh sieve; the pregelatinized corn starch is a high-amylose pregelatinized corn starch with a linear content of more than 75%;

[0208] The formula includes the following components in parts by weight:

[0209] Hydroxypropyl methylcellulose ether 85.0%,

[0210] Polyethylene glycol 9.0%,

[0211] Pregelatinized corn starch 3.0%,

[0212] 1.5% mixture of hydrophilic modified graphene dispersion and SN-DISPERSANT 5040,

[0213] Polycarboxylic acid high performance water reducer Zhaojia Technology ZC-PC8310 1.0%,

[0214] Melamine high efficiency water reducing agent Zhaojia Technology SMF 0.5%.

[0215] Comparative Example 11

[0216] A method for preparing hydroxypropyl methylcellulose ether for interior wall neutral putty comprises the following steps:

[0217] S1. Mixing a hydrophilic modified graphene dispersion and a sodium polycarboxylate liquid dispersant to obtain a liquid modifier; the hydrophilic modified graphene dispersion has a solid content of 5wt%, a hydroxyl mass content of 16.0%, and a carboxyl mass content of 7.0%; the sodium polycarboxylate is a sodium polycarboxylate liquid dispersant SN-DISPERSANT 5040 from San Nopco;

[0218] S2. After the alkalization, etherification and neutralization reactions are completed, when HPMC (methoxy mass content is 27.3%, hydroxypropoxy content is 10.5%) enters the granulation stage, the liquid modifier is sprayed evenly on the surface of the HPMC gel after filter pressing through a spray device, so that the liquid modifier and HPMC are evenly mixed to obtain a modified HPMC gel;

[0219] S3, granulating the modified HPMC gel material to prepare granular modified HPMC; performing low-temperature crushing on the granular modified HPMC, controlling the crushing temperature at about 60° C., and actually controlling the crushing temperature at 55-65° C., to obtain modified HPMC powder;

[0220] S4. According to the formula, the modified HPMC powder is physically mixed with a water reducer, pregelatinized corn starch and polyethylene glycol by an air flow mixer to obtain the hydroxypropyl methylcellulose ether for the neutral putty for interior walls; the polyethylene glycol has a molecular weight of 6000Da and is sieved through a 100-mesh sieve; the pregelatinized corn starch is a high-amylose pregelatinized corn starch with a linear content of more than 75%;

[0221] The formula includes the following components in parts by weight:

[0222] Hydroxypropyl methylcellulose ether 85.0%,

[0223] Polyethylene glycol 9.0%,

[0224] Pregelatinized corn starch 3.0%,

[0225] 1.5% mixture of hydrophilic modified graphene dispersion and SN-DISPERSANT 5040,

[0226] Polycarboxylic acid high performance water reducer Zhaojia Technology ZC-PC8310 1.0%,

[0227] Melamine high efficiency water reducing agent Zhaojia Technology SMF 0.5%.

[0228] Comparative Example 12

[0229] A method for preparing hydroxypropyl methylcellulose ether for interior wall neutral putty comprises the following steps:

[0230] S1. Mixing a hydrophilic modified graphene dispersion and a sodium polycarboxylate liquid dispersant to obtain a liquid modifier; the hydrophilic modified graphene dispersion has a solid content of 5wt%, a hydroxyl mass content of 16.0%, and a carboxyl mass content of 7.0%; the sodium polycarboxylate is a sodium polycarboxylate liquid dispersant SN-DISPERSANT 5040 from San Nopco;

[0231] S2. After the alkalization, etherification and neutralization reactions are completed, when HPMC (methoxy mass content is 21.3%, hydroxypropoxy content is 10.3%) enters the granulation stage, the liquid modifier is sprayed evenly on the surface of the HPMC gel after the filter press through a spray device, so that the liquid modifier and HPMC are evenly mixed to obtain a modified HPMC gel;

[0232] S3, granulating the modified HPMC gel material to prepare granular modified HPMC; performing low-temperature crushing on the granular modified HPMC, controlling the crushing temperature at about 70° C., and actually controlling the crushing temperature at 65-75° C., to obtain modified HPMC powder;

[0233] S4. According to the formula, the modified HPMC powder is physically mixed with a water reducer, pregelatinized corn starch and polyethylene glycol by an air flow mixer to obtain the hydroxypropyl methylcellulose ether for the neutral putty for interior walls; the polyethylene glycol has a molecular weight of 6000Da and is sieved through a 100-mesh sieve; the pregelatinized corn starch is a high-amylose pregelatinized corn starch with a linear content of more than 75%;

[0234] The formula includes the following components in parts by weight:

[0235] Hydroxypropyl methylcellulose ether 85.0%,

[0236] Polyethylene glycol 9.0%,

[0237] Pregelatinized corn starch 3.0%,

[0238] 1.5% mixture of hydrophilic modified graphene dispersion and SN-DISPERSANT 5040,

[0239] Polycarboxylic acid high performance water reducer Zhaojia Technology ZC-PC8310 1.0%,

[0240] Melamine high efficiency water reducing agent Zhaojia Technology SMF 0.5%.

[0241] The performance of the hydroxypropyl methylcellulose ether for neutral putties for interior walls prepared in Examples 1 to 4 and Comparative Examples 1 to 12 was tested.

[0242] Among them, the viscosity index is tested according to JCT 2190-2013 "Cellulose ether for building dry-mix mortar";

[0243] Water retention index: refer to JGJT70 water retention test, and after optimization, adopt the internal control test method of Zhongwei Pharmaceutical as follows: weigh 100 g gypsum and 0.15 g cellulose ether and mix them evenly, add 65 g water and stir, weigh 20 medium-speed qualitative filter papers, record the dry weight M1, place the barrel mold on the medium-speed filter paper, pour in the stirred slurry, let it stand for 6 min, weigh the weight of the filter paper after water absorption M2, and record the weight of the filter paper of the blank sample (without cellulose ether) as M3, and the weight after water absorption as M4. The water retention rate calculation method is: {1-(M2-M1) / (M4-M3)}*100%;

[0244] VOC content: Tested according to the highest requirements for VOC content in GB 18582-2020 "Limits of Hazardous Substances in Architectural Wall Coatings";

[0245] Tensile bond strength ratio (23°C) / %: Tested in accordance with JCT 2190-2013 Cellulose ether for building dry-mix mortar;

[0246] Tensile bond strength ratio (-20℃) / %: Refer to the tensile bond strength ratio in JCT 2190-2013 "Cellulose ether for building dry-mixed mortar", and test after the curing temperature is changed to -20℃. The index requirement must be ≥80%;

[0247] Workability: Refer to the method in JG / T 298-2010 "Putty for Building Interiors" for testing, and divide the workability into the following levels: (4.0-5.0, smooth hand feeling, smooth scraping), (2.5-3.9, smooth hand feeling, average scraping), (<2.5, heavy hand feeling, obstructed scraping); Note: The higher the score, the better the workability;

[0248] Water requirement: Test according to 6.11.3 of JCT 2190-2013 Cellulose ether for building dry-mix mortar;

[0249] Thixotropy: According to the company's internal testing method, it is divided into the following levels: (2.0-3.0, high thixotropy), (1.0-1.9, average thixotropy), (<1.0, poor thixotropy); Note: The higher the score, the better the thixotropic performance;

[0250] Thickening rate and thinning rate: refer to JGJT70 consistency test (cone penetration method), and record the initial cone penetration M1. After standing for 30 minutes, re-test according to the standard and record the cone penetration M2. After completing the M2 test, immediately use an electric stirrer with a speed of 100r / min to stir the slurry in the container for 10s, and then re-test according to the standard and record the cone penetration M3;

[0251] The thickening rate is calculated as {(M1-M2) / M1}*100%;

[0252] The calculation method of the dilution rate is {(M3-M1) / M1}*100%.

[0253] The performance test results are shown in Table 1.

[0254] Table 1 Performance table of various indicators

[0255] Test items Viscosity (20℃, mPa·s) Water retention rate / % VOC content (g / kg) Tensile bond strength ratio (23℃) / % Tensile bond strength ratio (-20℃) / % Construction Water requirement / % Thixotropy Thickening rate / % Dilute rate / % Example 1 105000 92.1 Not detected ≥100 89.9 4.5 40 3.0 7.5 5.5 Example 2 109000 92.5 Not detected ≥100 90.0 4.6 40 3.0 7.2 5.4 Example 3 100800 91.8 Not detected ≥100 90.2 4.5 40 3.0 6.9 6.1 Example 4 105500 92.5 Not detected ≥100 90.8 4.4 40 3.0 6.0 4.2 Comparative Example 1 155000 93.7 Not detected ≥100 91.3 3.0 46 3.0 21.3 15.5 Comparative Example 2 96000 89.6 Not detected ≥100 53.5 3.2 35 1.5 18.4 21.7 Comparative Example 3 84500 88.2 Not detected ≥100 90.6 1.5 28 0.5 7.9 8.3 Comparative Example 4 107000 91.8 Not detected ≥100 15.5 4.3 38 2.6 6.8 7.2 Comparative Example 5 112000 92.6 Not detected ≥100 60.6 4.2 37 2.6 7.2 6.7 Comparative Example 6 106500 90.2 Not detected ≥100 62.5 4.2 36 2.6 7.0 6.4 Comparative Example 7 145000 93.4 Not detected ≥100 89.5 3.3 50 2.2 13.2 4.1 Comparative Example 8 89000 88.9 Not detected ≥100 88.7 3.8 34 2.8 6.6 9.2 Comparative Example 9 115000 85.3 Not detected ≥100 88.5 3.9 39 3.0 14.8 13.6 Comparative Example 10 107000 91.1 Not detected ≥100 85.6 3.6 40 3.0 15.1 11.9 Comparative Example 11 105000 90.4 Not detected ≥100 88.3 3.7 40 3.0 18.9 21.2 Comparative Example 12 16000 90.1 Not detected ≥100 89.6 4.1 40 2.1 12.3 14.9

Claims

1. A method for preparing hydroxypropyl methylcellulose ether for interior wall neutral putty, comprising the following steps: S1, mixing the hydrophilic modified graphene dispersion and the polycarboxylate sodium salt liquid dispersant to obtain a liquid modifier; S2, when HPMC enters the granulation stage, the liquid modifier is sprayed evenly on the surface of the HPMC gel after filter pressing through a spray device, so that the liquid modifier and HPMC are evenly mixed to obtain a modified HPMC gel; S3, granulating the modified HPMC gel material to prepare granular modified HPMC; performing low-temperature pulverization on the granular modified HPMC, controlling the pulverization temperature at 65-75° C., to obtain modified HPMC powder; S4, physically mixing the modified HPMC powder with a water reducer, pregelatinized starch, and polyethylene glycol by an air flow mixer according to the formula to obtain the hydroxypropyl methylcellulose ether for the interior wall neutral putty; The formula includes the following components in parts by weight: Polyethylene glycol 5~10%, A mixture of hydrophilic modified graphene dispersion and polycarboxylic acid sodium salt 1.5~2.0%, Water reducing agent 1.5~3.0%, Pregelatinized starch 1~3%, The balance is hydroxypropyl methylcellulose ether; The hydrophilic modified graphene dispersion has a solid content of 4-8%, a hydroxyl mass content of 15-20%, and a carboxyl mass content of 4-8%; In step S2, the methoxy mass content of the HPMC is 27-30%, and the hydroxypropoxy mass content is 10-13%.

2. The method for preparing hydroxypropyl methylcellulose ether for neutral putty for interior walls according to claim 1, characterized in that: The molecular weight of the polyethylene glycol is 6000 Da.

3. The method for preparing hydroxypropyl methylcellulose ether for neutral putty for interior walls according to claim 2, characterized in that: The particle size fineness of the polyethylene glycol is not less than 180 μm.

4. The method for preparing hydroxypropyl methylcellulose ether for neutral putty for interior walls according to claim 1, characterized in that: The polycarboxylate sodium salt is a polycarboxylate sodium salt liquid dispersant SN-DISPERSANT 5040 produced by San Nopco.

5. The method for preparing hydroxypropyl methylcellulose ether for neutral putty for interior walls according to claim 1, characterized in that: The water reducing agent is composed of a polycarboxylic acid high-performance water reducing agent and a melamine high-efficiency water reducing agent in a mass ratio of (1-4):

1.

6. The method for preparing hydroxypropyl methylcellulose ether for neutral putty for interior walls according to claim 1, characterized in that: In the mixture of the hydrophilic modified graphene dispersant and the sodium polycarboxylate, the mass ratio of the hydrophilic modified graphene dispersion to the sodium polycarboxylate is 1:

1.

7. The method for preparing hydroxypropyl methylcellulose ether for neutral putty for interior walls according to claim 1, characterized in that: The pregelatinized starch is a high-amylose pregelatinized corn starch with an amylose content of more than 75%.

8. The method for preparing hydroxypropyl methylcellulose ether for neutral putty for interior walls according to claim 5, characterized in that: The polycarboxylic acid high-performance water reducer is ZC-PC8310 produced by Zhaojia Technology, and the melamine high-efficiency water reducer is SMF produced by Zhaojia Technology.