CN110628357B

CN110628357B - Semi-dry preparation method of modified starch rich in nano particles for wallpaper adhesive

Info

Publication number: CN110628357B
Application number: CN201910494609.1A
Authority: CN
Inventors: 姚臻; 杨勇; 姚献平; 郑丽萍
Original assignee: Shandong Zhongyou Biotechnology Co ltd
Current assignee: Shandong Zhongyou Biotechnology Co.,Ltd.
Priority date: 2019-06-06
Filing date: 2019-06-06
Publication date: 2021-01-01
Anticipated expiration: 2039-06-06
Also published as: CN110628357A

Abstract

The invention relates to the field of wallpaper adhesives, and discloses a semi-dry preparation method of modified starch for wallpaper adhesives rich in nano particles, which comprises the following steps: 1) mixing and pre-alkalizing; 2) dispersing and activating treatment; 3) performing a group strengthening reaction; 4) a carboxymethyl etherification reaction; 5) and (5) performing synergistic treatment. The invention uses a special semi-dry process to prepare the modified starch product for the wallpaper adhesive. The product is applied to the production of the wallpaper adhesive, and the composition material for the wallpaper adhesive, which has good cold water solubility, strong compatibility, high cohesive force, stable freeze thawing, good environmental protection and high glue opening amount, can be prepared without heating and decocting in the dispersion process.

Description

Semi-dry preparation method of modified starch rich in nano particles for wallpaper adhesive

Technical Field

The invention relates to the field of wallpaper adhesives, in particular to a semi-dry preparation method of modified starch for wallpaper adhesives rich in nano particles.

Background

Wallpaper, also called wall paper, is an interior decoration material widely used in modern decoration industry. The paint has the characteristics of rich patterns, various colors, luxury, safety, environmental protection, convenient construction, proper price and the like, and is popularized in developed countries and regions such as Europe and America, southeast Asia, Japan and the like to a great extent. As a decorative material, the wallpaper can achieve good indoor decoration effect only by matching with special wallpaper glue with excellent performance. At present, the common wallpaper glue in the market mostly contains harmful substances such as free (condensed) aldehyde, VOC, phenol, aromatic hydrocarbon, organic volatile matters and the like, and is harmful to human health and environment, so that people have certain rejection psychology to the products, and the conventional white glue and ethylene polymer products belong to non-renewable resources, so that a large amount of energy is consumed, the conventional product quality is uneven, and the pollution to the human environment is increasingly serious.

Through the inquiry of published patents and existing products, the following can be known:

wu Lei et al of Henan Henry disclose modified starch for environment-friendly starch-based wallpaper adhesive and a preparation method thereof in patent CN104497155A (B), wherein starch is mainly used for preparing a starch product applicable to wallpaper adhesive by utilizing cross-linking and etherification process technologies under wet process conditions.

Roolijing, Guandongmei, et al, in patent CN108003247A discloses a method for preparing modified starch for wallpaper glue, which mainly utilizes the techniques of starch oxidation, crosslinking and vinyl acetate esterification under the wet condition to obtain a starch product for wallpaper glue.

Patent CN106433512A of Bingnan university discloses a wallpaper adhesive for preparing starch by oxidation and coupling gelatinization process, which utilizes a starch product which is obtained by oxidation, gelatinization, re-oxidation and coupling technology of starch under wet condition and can be used for wallpaper adhesive.

Wutongming of Jia Li Feng et al in patent CN106256836A disclose an environment-friendly modified starch for starch-based wallpaper adhesive and a preparation method thereof, which is a wallpaper adhesive starch product prepared by compounding raw starch, sodium citrate, disodium ethylene diamine tetraacetate, sodium trimetaphosphate and the like, which not only can effectively remove heavy metal ions, but also has white color and is not easy to become diluted water.

Patent CN108084285A discloses an environment-friendly modified starch for wallpaper glue and a preparation method thereof. The starch product for the wallpaper adhesive is prepared by mainly utilizing waxy starch, cassava starch and the like through etherification and crosslinking.

Patent CN201810252482, sun pure et al, of all the kingdoms, discloses a preparation process of a water-resistant environment-friendly wallpaper adhesive, which mainly utilizes pre-gelatinized cross-linked octenyl succinic acid starch aluminum, pre-gelatinized oxidized cross-linked starch and the like to mix and prepare the processing process of the water-resistant environment-friendly wallpaper adhesive.

The invention discloses wallpaper glue for children room decoration and a preparation method thereof in patent CN107880811A, and provides wallpaper glue prepared by mixing and processing different types of starch materials, xanthan gum, glyceryl monostearate, mildew preventive and the like.

The technical solutions in the above related patents are summarized as follows: basically, different starch is utilized to prepare different types of products for wallpaper glue in a wet process or under a mixed technical condition. Generally, the production of industrial modified starch is divided into a wet method, a dry method and a semi-dry method, and the wet method production process needs to pass through: the modified starch is obtained by the steps of mixing raw starch, reacting, washing, dehydrating, drying, screening, obtaining a finished product and the like. However, at present, cold water soluble modified starch products are produced by a wet process and a large amount of organic solvents, a large amount of organic solvents are required to be added in the process to protect the normal operation of the reaction, and a plurality of problems of starch washing, organic solvent recovery, serious environmental pollution and the like are involved in the later period, so that the preparation of the products is difficult to effectively popularize in the wet production process.

Disclosure of Invention

In order to solve the technical problems, the invention provides a semi-dry preparation method of modified starch for wallpaper glue rich in nano particles. The product is applied to the production of the wallpaper adhesive, and the composition material for the wallpaper adhesive, which has good cold water solubility, high cohesive force, stable freeze thawing, good environmental protection and high glue yield, can be prepared without heating and decocting in the dispersion process.

The specific technical scheme of the invention is as follows: a semi-dry preparation method of modified starch for wallpaper glue rich in nanoparticles comprises the following steps:

1) mixing and pre-alkalizing: stirring the starch raw material, sequentially adding the nano particles and the alkali catalyst, and mixing and stirring.

2) Dispersing and activating treatment: adding a dispersing activating agent into the product obtained in the step 1), performing molecular activation modification treatment at 20-45 ℃ for 10-50min, and controlling the water content of the treated starch to be 15-30 wt%.

3) Group strengthening reaction: adding a mixture of a group enhancer and a characteristic improver into the product obtained in the step 2), and carrying out group enhancement reaction for 10-60min at the temperature of 20-60 ℃.

4) Carboxymethyl etherification reaction: adding a carboxymethyl etherifying agent into the product obtained in the step 2), and carrying out carboxymethyl bimolecular displacement etherification reaction for 30-200min at 50-90 ℃.

5) And (3) synergistic treatment: cooling the product obtained in the step 2), adding a synergistic agent for reaction, discharging, crushing, sieving and packaging to obtain a finished product.

In the above steps of the present invention, the main reaction mechanism is as follows:

1) mixing and pre-alkalizing: the starch raw material is stirred, nano particles and an alkali catalyst are sequentially added for mixing and stirring, the nano particles are mainly introduced to participate in modification treatment, a huge surface hydrophobic layer can be formed on the surface of starch molecules, the friction coefficient between the starch molecules is effectively reduced, the appearance shows that the powder has better flowability, the reaction efficiency is improved, the equipment load caused by high moisture is greatly reduced, the alkali catalyst is added, the alkali catalyst and the starch are mainly used for mixing and preprocessing, the pH value of a reaction system is improved, more reaction activity center points are provided, and more favorable conditions are created for the reaction of starch and a group strengthening auxiliary agent and the carboxymethyl etherification reaction in the later period.

2) Dispersing and activating treatment: the step is mainly to add a proper amount of dispersing activating agent on the basis of 1) reaction so as to provide a reaction environment between a starch wet method and a starch dry method, treat for a certain time under a certain temperature condition, effectively cooperate with an alkalization treatment stage, ensure to complete necessary modification treatment of the starch molecule surface to the maximum extent, and provide the molecular state of the optimal state for the reaction of the later stages of 3) and 4). Meanwhile, the moisture content is considered to be moderate, and the higher moisture content causes the increase of equipment load and the increase of manufacturing cost; the low moisture content leads to insufficient degree of surface modification treatment of starch molecules, difficult to provide enough reaction activation points, low efficiency of carboxymethyl etherification reaction, low viscosity and poor water solubility of modified starch products, and water-soluble products with high gel opening amount and high viscosity cannot be obtained.

3) Group strengthening reaction: the introduction of the mixture of the group enhancer and the characteristic improver in the reaction step is mainly to introduce active bifunctional groups, and carry out an enhanced reaction on the modified starch under the environment of proper temperature, reaction time and pH value, wherein alcohol hydroxyl groups of the starch and the group enhancer form a diether bond to form a multidimensional space network structure, so that the average molecular weight of the starch is obviously increased, the combination of hydrogen bonds between directly-connected starch and amylopectin in starch granules can be further improved and enhanced, and necessary reaction guarantee is provided for obtaining high-viscosity, glue-opening amount and moderate water-soluble products. Particularly, the premixed property improving agent and the radical reinforcing agent are introduced, so that the reaction activation contact surface of the radical reinforcing auxiliary agent and the alkalization modified starch can be effectively increased, the unit concentration and the reaction efficiency are improved, and meanwhile, the phenomenon that the reaction is uneven due to overhigh local concentration after the radical reinforcing agent is added, the index requirements of the starch product on high viscosity, moderate water solubility and high degumming amount are difficult to obtain, and the experiment failure is caused.

4) Carboxymethyl etherification reaction: the method mainly comprises the step of adding a carboxymethyl etherifying agent (preferably self-made) into a reactant, and preferentially carrying out bimolecular nucleophilic substitution reaction with alcoholic hydroxyl groups on starch C2 and C3, so that a modified starch primary product for cold-water-soluble wallpaper glue is obtained under the environment of proper temperature, reaction time and pH value.

5) And (3) synergistic treatment: the step is determined by comprehensively considering the application requirements of the starch product in the wallpaper adhesive, and the synergistic additive with proper amount and proportion is introduced in the process for adding and matching, so that the stability of the wallpaper adhesive product in the later period can be effectively improved, the shelf life is prolonged, the product application is improved, and the better use effect is achieved.

In conclusion, the invention realizes that the modified starch for the wallpaper adhesive is prepared by using the semidry process, can obviously save energy consumption, and overcomes the problems of high cost, high pollution, high energy consumption and the like caused by the wet production process. The process has the advantages of simple process, low energy consumption, short time consumption, no pollution, and no wastewater and waste residue discharge.

In addition, the nano particles are introduced into the formula, so that the anti-aging property of the powder can be effectively endowed, the uniqueness of the product such as activity degree, stability, dispersibility, weather resistance, sterilization, corrosion resistance and the like is improved, and the product has good comprehensive performances such as fracture resistance, film forming flexibility and the like.

The invention completes the production and forming of the modified starch for the wallpaper adhesive through the specific process steps of pretreatment and mixing, dispersion and activation treatment, radical strengthening reaction, carboxymethyl etherification reaction and synergistic treatment.

The key reason that the product of the invention can realize cold water solubility is as follows: by optimizing the process, proper powder fluidity, the use amount and time of the alkalization assistant, the temperature, the water content of the system, the control of the group strengthening reaction condition, the addition of a proper carboxymethyl etherification reagent and the like are controlled.

Preferably, in step 1), the starch material is selected from one or more of waxy corn starch, tapioca starch, corn starch, potato starch and wheat starch.

Preferably, in the step 1), the nano particles are selected from one or more of nano titanium dioxide, nano silicon dioxide and nano titanium tetroxide with the particle size of 10-40 nm; the dosage of the nano particles is 0.01-1% of the mass of the starch raw material.

The invention introduces nano particles in the reaction of starch raw materials for the first time, and can obviously reduce the equipment load and endow the product with better flow property under the condition of the preferable particle size and addition amount. Although the prior art CN107880811A 'wallpaper glue for children room decoration and preparation method thereof' also discloses the addition of nano particles. The present invention is fundamentally different therefrom. One of them is that: the starting point of the above patent is different, and the starting point of the above patent is mainly that a proper amount of nano particles are added after the wallpaper glue is prepared so as to enrich the product connotation. The starting point of the invention is that nano particles are introduced to participate in starch molecule modification treatment in the process of preparing modified starch by a semi-dry method, and a huge surface hydrophobic layer can be formed on the surface of starch molecules, so that the friction coefficient between the starch molecules is effectively reduced, the appearance shows that the powder has better flowability, the reaction efficiency can be effectively increased, and the equipment load caused by high moisture is greatly reduced (obviously, the addition mode of the patent cannot achieve the technical effect). The second is that: the patent is directly the production of wallpaper glue, but the invention is the addition which is beneficial to the reaction in the production process of modified starch products. It is then the case that the modified starch product of the invention is used in the production of wallpaper glue.

Preferably, in the step 1), the alkali catalyst is selected from one or more of triethanolamine, sodium metasilicate, sodium hydroxide, sodium aluminate, potassium hydroxide, calcium hydroxide, sodium carbonate and disodium hydrogen phosphate; the amount of the catalyst is 3-8% of the mass of the starch raw material; mixing and stirring for 5-60 min.

As one of the key points, the alkali consumption in the reaction stage of the step 1) is properly controlled within the range of 3-8%, and the water content is properly controlled within the range of 15.0-30.0%, so that a high-efficiency product with good water solubility and moderate dissolution speed can be prepared within a certain time.

Preferably, in the step 2), the dispersion activating agent is a mixture of one or more of ethanol, fatty alcohol polyether sulfate, isopropanol, PEG-400 and fatty alcohol-polyoxyethylene ether and water; the dosage of the dispersing activator is 5-25% of the mass of the starch raw material, and the concentration of the dispersing activator is 60-90 wt%; the reaction temperature is 20-45 deg.C, and the reaction time is 10-50 min.

The mixture of the dispersion activating reagent and water must be strictly controlled in concentration range of 60-90% in order to obtain a low-cost, high-efficiency product.

Preferably, in the step 3), the group enhancer is one or more of adipic acid acetic anhydride mixture, dimethylol urea, cyanuric chloride and 3-chloro-1, 2-propylene oxide;

the dosage of the mixture of the group enhancer and the characteristic improver is 0.005-2% of the mass of the starch raw material. The mass ratio of the characteristic improver to the group enhancer is 5-15: 1.

Preferably, in the step 3), the characteristic improving agent is one or more of carbon tetrachloride, ethanol, chloroform, trichloroethylene and isopropanol.

Preferably, in the step 3), the reaction temperature is 25-50 ℃ and the reaction time is 15-60 min.

Preferably, in the step 4), the reaction temperature is 45-100 ℃ and the reaction time is 60-180 min.

Preferably, in step 4), the carboxymethyl etherifying agent used is prepared by: mixing monochloroacetic acid and alkaline agent according to the mass ratio of 1: 0.3-0.98, reacting for 30-200min, sealing and packaging for later use; the dosage of the carboxymethyl etherifying agent is 8-30% of the mass of the starch raw material.

Compared with single monochloroacetic acid, the self-made carboxymethyl etherifying agent adopted by the invention has the following advantages: (1) the sodium chloroacetate is simple to prepare, the etherification reaction conditions are milder and more stable, and the reaction efficiency is higher. (2) Acute poisoning may occur when humans inhale high concentrations of monochloroacetic acid vapor or contact the skin with solutions thereof. And the sodium chloroacetate is safer to use and is beneficial to storage.

Preferably, in the step 5), the synergistic auxiliary agent is one or more of VAE, PVAC, PVA micropowder, citric acid, fumaric acid, oxalic acid, sodium benzoate, natamycin and bronopol; the amount of the synergistic auxiliary agent is 0.5-3.5% of the mass of the starch raw material, the reaction temperature is 40-60 ℃, and the reaction time is 10-60 min.

The invention creatively adopts the radical enhancer to compound the characteristic improver, and can obtain the starch product which has high consistency and high glue opening amount and is suitable for the wallpaper glue industry.

Compared with the prior art, the invention has the beneficial effects that:

1. the invention adopts a semidry process, has no three-waste discharge in the process, is stable in gelling and storage, safe and environment-friendly, has no release of harmful substances such as formaldehyde, benzene and the like, and belongs to an environment-friendly product.

2. The product of the invention can be dispersed into thick colloid by cold water, and has obvious advantage in comparison with the cost of other starch products which can be used after being decocted into colloid.

3. The product of the invention has high viscosity, large glue opening amount, high consistency, excellent freeze-thaw resistance and excellent comprehensive cost performance, thereby providing more product selection space for wallpaper glue production enterprises and enhancing the market competitiveness of wallpaper glue products.

4. The nano particles are introduced into the formula of the invention, so that the reaction load can be effectively reduced, the powder flow characteristic is increased, the reaction efficiency is improved, the powder has unique performances of ageing resistance, high activity, stability, dispersibility, weather resistance, sterilization, corruption resistance, automatic air purification and the like, and the invention has better performances in the comprehensive performances of fracture resistance, flexibility and the like.

Reference numerals

FIG. 1 is a photograph showing the dissolution of the starches obtained in examples 1 to 5 in cold water (examples 1 to 5 in the order from left to right);

FIG. 2 is a photograph showing the dissolution of the starches obtained in comparative examples 1 to 7 in cold water (comparative examples 1 to 7 in the order from left to right).

Detailed Description

The process of the present invention will be described in detail below with reference to specific examples, which are provided only for those skilled in the art and may be varied in terms of optimum formulation and synthesis. The raw materials and auxiliary materials used in the examples can be purchased from the market and can be prepared by adopting a conventional method. (materials in examples are in parts by mass)

General examples

A semi-dry preparation method of modified starch for wallpaper glue rich in nanoparticles comprises the following steps:

1) mixing and pre-alkalizing: stirring the starch raw material, sequentially adding the nano particles and the alkali catalyst, mixing and stirring for 5-60 min.

The starch raw material is one or more selected from waxy corn starch, cassava starch, corn starch, potato starch and wheat starch.

The nano particles are selected from one or more of nano titanium dioxide, nano silicon dioxide and nano titanium tetroxide with the particle size of 10-40 nm; the dosage of the nano particles is 0.01-1% of the mass of the starch raw material. The alkali catalyst is selected from one or more of triethanolamine, sodium metasilicate, sodium hydroxide, sodium aluminate, potassium hydroxide, calcium hydroxide, sodium carbonate and disodium hydrogen phosphate; the dosage of the catalyst is 3-8% of the mass of the starch raw material.

2) Dispersing and activating treatment: adding a dispersing activating agent into the product obtained in the step 1), and performing molecular activation modification treatment at 15-50 ℃ (preferably 20-45 ℃) for 5-60min (preferably 10-50min), wherein the water content of the starch after treatment is controlled at 15-30 wt%.

The dispersing activator is a mixture of one or more of ethanol, fatty alcohol polyether sulfate, isopropanol, PEG-400 and fatty alcohol-polyoxyethylene ether and water; the dosage of the dispersing activator is 5-25% of the mass of the starch raw material, and the concentration of the dispersing activator is 60-90 wt%.

3) Group strengthening reaction: adding a mixture of a group enhancer and a characteristic improver into the product obtained in the step 2), and performing group enhancement reaction for 10-60min (preferably 15-60min) at 20-60 ℃ (preferably 25-50 ℃).

The group enhancer is one or more of adipic acid acetic anhydride mixture, dimethylol urea, cyanuric chloride and 3-chloro-1, 2-epoxypropane; the characteristic improving agent is one or more of carbon tetrachloride, ethanol, chloroform, trichloroethylene and isopropanol. The dosage of the mixture of the group enhancer and the characteristic improver is 0.005-2% of the mass of the starch raw material; the mass ratio of the characteristic improver to the group enhancer is 5-15: 1.

4) Carboxymethyl etherification reaction: adding a carboxymethyl etherifying agent into the product obtained in the step 2), and carrying out carboxymethyl bimolecular substitution etherification reaction for 30-200min (preferably 60-180min) at 30-120 ℃ (preferably 45-100 ℃).

The preparation method of the carboxymethyl etherifying agent comprises the following steps: mixing monochloroacetic acid and alkaline agent according to the mass ratio of 1: 0.3-0.98, reacting for 30-200min, sealing and packaging for later use; the dosage of the carboxymethyl etherifying agent is 8-30% of the mass of the starch raw material.

The synergistic auxiliary agent is one or more of VAE, PVAC, PVA micro powder, citric acid, fumaric acid, oxalic acid, sodium benzoate, natamycin and bronopol; the dosage of the synergistic auxiliary agent is 0.5-3.5% of the mass of the starch raw material, and the mixing proportion is generally recommended as follows: 1: 10: 16, the mixing reaction temperature is 40-60 ℃, and the reaction time is 10-60 min.

Example 1

Preparation of the carboxymethyl etherifying agent: mixing monochloroacetic acid and alkaline reagent according to the mass ratio of 1: 0.65, reacting for 75min at 55 ℃, sealing and packaging for later use.

Adding 500kg of waxy corn starch and potato starch in a ratio of 1: 1 into a 3000L kneader, starting the kneader, sealing a reaction kettle, adding 0.5kg of nano titanium dioxide and 32kg of calcium hydroxide, mixing and pretreating for 10min, then adding 60kg of mixed reagent of water and isopropanol in a ratio of 1: 5, dispersing at 40 deg.C for 40min, adding 0.6kg mixture of ethanol and dimethylol urea (8: 1), stirring and reacting for 30min at the temperature of 40 ℃, then adding 65kg of self-made carboxymethyl etherifying agent, stirring, heating to 65 ℃, carrying out thermal insulation etherification for 100min, cooling to 40 ℃ after the reaction time, adding 13.5kg of natamycin, citric acid and PVA micropowder reagent which are mixed according to the proportion of 1: 10: 16 into the reaction kettle, stirring for reaction for 15min, discharging, crushing and packaging to obtain the finished product.

Example 2

Preparation of the carboxymethyl etherifying agent: mixing monochloroacetic acid and alkaline agent according to the mass ratio of 1: 0.5, reacting for 80min, sealing and packaging for later use.

Adding 500kg of corn starch and 500kg of potato starch in a ratio of 1: 1 into a 3000L kneader, starting the kneader, sealing a reaction kettle, adding 0.5kg of nano titanium dioxide and 30kg of sodium metasilicate, mixing and pretreating for 10min, then adding 80kg of mixed reagent of water and ethanol in a ratio of 1: 6, dispersing at 45 deg.C for 40min, adding 1kg of mixture treated with isopropanol and 3-chloro-1, 2-epoxypropane (ratio of 10: 1), stirring and reacting for 30min at the temperature of 40 ℃, then adding 65kg of self-made carboxymethyl etherifying agent, stirring for 10min, heating to 60 ℃, carrying out thermal insulation etherification reaction for 120min, cooling to 40 ℃ after reaction time, adding 10kg of natamycin, oxalic acid and PVA micropowder reagent which are mixed according to the proportion of 1: 10: 16 into a reaction kettle, stirring for reaction for 15min, discharging, crushing and packaging to obtain the finished product.

Example 3

Preparation of the carboxymethyl etherifying agent: mixing and stirring monochloroacetic acid and an alkaline agent in a mass ratio of 1: 0.8 in an open mixer for reaction for 90min, and sealing and packaging for later use.

Adding 500kg of corn starch into a 3000L kneader, starting the kneader, sealing a reaction kettle, adding 0.5kg of nano titanium dioxide and 35kg of sodium carbonate, performing mixing pretreatment for 20min, adding 70kg of a mixed reagent of water and glycerol in a ratio of 1: 5, performing dispersion treatment at 42 ℃ for 45min, adding 0.5kg of a mixed adipic acid-acetic anhydride mixture processed by ethanol (in a ratio of 9: 1), stirring and reacting at 40 ℃ for 40min, adding 100kg of a self-made carboxymethyl etherifying agent, stirring for 10min, heating to 58 ℃, performing heat preservation and etherification for 100min, cooling to 40 ℃ after the reaction time, adding 12kg of a natamycin, citric acid and PVA micropowder reagent mixed in a ratio of 1: 10: 16 into the reaction kettle, stirring and reacting for 15min, discharging, crushing and packaging to obtain the finished product.

Example 4

Preparation of the carboxymethyl etherifying agent: mixing monochloroacetic acid and alkaline agent according to the mass ratio of 1: 0.5, reacting for 120min, sealing and packaging for later use.

Adding 500kg of waxy corn starch into a 3000L kneader, starting the kneader, sealing the reaction kettle, adding 0.8kg of nano silicon dioxide and 25kg of sodium hydroxide, mixing and pretreating for 20min, adding 45kg of mixed reagent of water and ethanol in a ratio of 1: 6 in a metered manner, dispersing at 40 deg.C for 50min, adding 1.2kg of 3-chloro-1, 2-epoxypropane treated with isopropyl alcohol at a ratio of 10: 1, stirring and reacting for 40min at the temperature of 40 ℃, then adding 60kg of self-made carboxymethyl etherifying agent, stirring for 10min, heating to 68 ℃, carrying out thermal insulation etherification reaction for 90min, cooling to 40 ℃ after reaction time, adding 14kg of sodium benzoate, fumaric acid and VAE micro powder reagent which are mixed according to the proportion of 1: 10: 16 into a reaction kettle, stirring for reaction for 15min, discharging, crushing and packaging to obtain the finished product.

Example 5

Preparation of the carboxymethyl etherifying agent: mixing monochloroacetic acid and alkaline agent according to the mass ratio of 1: 0.45, reacting for 50min, sealing and packaging for later use.

1: 2 potato starch was added to a 3000L kneader: 500kg of wheat starch, starting a kneader, sealing a reaction kettle, adding 0.7kg of nano silicon dioxide and 20kg of sodium hydroxide, performing mixing pretreatment for 10min, adding 58kg of mixed reagent of water and methanol in a ratio of 1: 6, performing dispersion treatment for 40min at the temperature of 42 ℃, adding 0.9kg of mixed adipic acid acetic anhydride mixture liquid treated by isopropanol (in a ratio of 12: 1), stirring and reacting for 40min at the temperature of 42 ℃, adding 70kg of self-made carboxymethyl etherifying agent, stirring for 15min, heating to 60 ℃, performing heat preservation and etherification for 120min, cooling to 40 ℃ after reaction time, adding 12kg of bronopol, fumaric acid and VAE micro powder reagent mixed according to a ratio of 1: 10: 16 into the reaction kettle, stirring and reacting for 15min, discharging, crushing and packaging to obtain the finished product.

Comparative example 1

Adopting a conventional wet process: 162 g of corn starch was added to 200g of an aqueous 80% methanol solution, which had been mixed with 72 g of sodium hydroxide in advance, and 75.2 g of monochloroacetic acid was added thereto with stirring, and after mixing for 30 minutes, the temperature was raised to 60 ℃ to react for 16 hours, and the sample of comparative example 1 was obtained after neutralization, filtration and washing.

Comparative example 2 (different from example 1 in that a different etherifying agent is used)

Adding 500kg of waxy corn starch and potato starch in a ratio of 1: 1 into a 3000L kneader, starting the kneader, sealing a reaction kettle, adding 0.5kg of nano titanium dioxide and 32kg of calcium hydroxide, performing mixing pretreatment for 10min, metering 60kg of a mixed reagent of water and isopropanol in a ratio of 1: 5, performing dispersion treatment at 40 ℃ for 40min, adding 1kg of 3-chloro-1, 2-epoxypropane in a ratio of 10: 1, performing stirring reaction at 40 ℃ for 30min, adding 65kg of monochloroacetic acid, stirring for 10min, heating to 65 ℃, performing heat preservation etherification for 100min, cooling to 40 ℃ after the reaction time, adding 13.5kg of natamycin, citric acid and PVA micropowder reagent mixed in a ratio of 1: 10: 16 into the reaction kettle, stirring for 15min, discharging, packaging and packaging to obtain the finished product, comparative example 2 sample was obtained.

Comparative example 3 (difference from example 1 in that no nanoparticles were added)

Adding 500kg of waxy corn starch and potato starch in a ratio of 1: 1 into a 3000L kneader, starting the kneader, adding 32kg of calcium hydroxide (without adding nano particles) after a closed reaction kettle, carrying out mixing pretreatment for 10min, then adding 60kg of mixed reagent of water and isopropanol in a ratio of 1: 5, carrying out dispersion treatment for 40min at the temperature of 40 ℃, then adding 1kg of 3-chloro-1, 2-epoxypropane treated by ethanol and mixed (in a ratio of 10: 1) into the mixture, stirring the mixture for reaction for 30min at the temperature of 40 ℃, then adding 65kg of self-made carboxymethyl etherifying agent (such as the embodiment 1), stirring the mixture for 10min, then heating the mixture to 65 ℃, carrying out heat preservation and etherification for 100min, cooling the mixture to 40 ℃ after the reaction time, adding 13.5kg of natamycin micropowder, citric acid and PVA micropowder reagent mixed in a ratio of 1: 10: 16 into the reaction kettle, stirring the mixture for reaction for 15min, then crushing the mixture, and packaging the finished product, comparative example 3 sample was obtained.

Comparative example 4 (different from example 1 in that no property improver was added)

Adding 500kg of waxy corn starch and potato starch in a ratio of 1: 1 into a 3000L kneader, starting the kneader, sealing a reaction kettle, adding 0.5kg of nano titanium dioxide and 32kg of calcium hydroxide, performing mixing pretreatment for 10min, metering 60kg of a mixed reagent of water and isopropanol in a ratio of 1: 5, performing dispersion treatment at 40 ℃ for 40min, adding 0.6kg of 3-chloro-1, 2-epoxypropane (without a characteristic improver), stirring and reacting at 40 ℃ for 30min, adding 65kg of a self-made etherifying agent (as in example 1), stirring for 10min, heating to 65 ℃ for thermal insulation etherification for 100min, cooling to 40 ℃ after the reaction time, adding 13.5kg of natamycin, citric acid and PVA micropowder reagent mixed according to a ratio of 1: 10: 16 into the reaction kettle, stirring and reacting for 15min, discharging, crushing and packaging to obtain a finished product, comparative example 4 was obtained.

Comparative example 5 (different from example 1 in that the amount of the nanoparticles and the alkali catalyst is out of the scope of the claims) 500kg of waxy corn starch and potato starch in a ratio of 1: 1 are added into a 3000L kneader, the kneader is started, 8kg of nano titanium dioxide and 10kg of calcium hydroxide are added after the reaction kettle is closed, the pre-treatment is carried out for 10min, 60kg of a mixed reagent of water and isopropanol in a ratio of 1: 5 is metered, the mixture is dispersed at the temperature of 40 ℃ for 40min, 1kg of 3-chloro-1, 2-propylene oxide which is well mixed (in a ratio of 10: 1) and treated by ethanol is added, the mixture is stirred and reacted at the temperature of 40 ℃ for 30min, 65kg of self-made etherifying agent (such as example 1) is added, the mixture is stirred for 10min, the temperature is raised to 65 ℃ for etherification reaction for 100min, the temperature is reduced to the temperature of 40 ℃ after the reaction time, and adding 13.5kg of natamycin, citric acid and PVA micropowder reagent which are mixed according to the ratio of 1: 10: 16 into the reaction kettle, stirring and reacting for 15min, discharging, crushing and packaging to obtain the sample of the comparative example 5.

Comparative example 6 (different from example 1 in that the etherifying agent is used in an amount out of the scope of claims)

Adding 500kg of waxy corn starch and potato starch in a ratio of 1: 1 into a 3000L kneader, starting the kneader, sealing a reaction kettle, adding 0.5kg of nano titanium dioxide and 32kg of calcium hydroxide, performing mixing pretreatment for 10min, metering 60kg of a mixed reagent of water and isopropanol in a ratio of 1: 5, performing dispersion treatment at 40 ℃ for 40min, adding 1kg of 3-chloro-1, 2-epoxypropane processed by ethanol (the ratio is 10: 1) and mixed, stirring and reacting for 30min at 40 ℃, adding 160kg of a self-made etherifying agent (such as example 1), stirring for 10min, heating to 65 ℃, performing heat preservation and etherification for 100min, cooling to 40 ℃ after the reaction time, adding 13.5kg of natamycin, sodium citrate and PVA micropowder reagent mixed according to a ratio of 1: 10: 16 into the reaction kettle, stirring and reacting for 15min, discharging, crushing and packaging to obtain a finished product, comparative example 6 was obtained.

Comparative example 7 (different from example 1 in that the radical strengthening reaction time is out of the scope of claims)

Adding 500kg of waxy corn starch and potato starch in a ratio of 1: 1 into a 3000L kneader, starting the kneader, sealing a reaction kettle, adding 0.5kg of nano titanium dioxide and 32kg of calcium hydroxide, performing mixing pretreatment for 10min, metering 60kg of a mixed reagent of water and isopropanol in a ratio of 1: 5, performing dispersion treatment at 40 ℃ for 120min, adding 1kg of 3-chloro-1, 2-epoxypropane processed by ethanol (the ratio is 10: 1) and mixed, stirring and reacting for 100min at 40 ℃, adding 65kg of a self-made etherifying agent (such as example 1), stirring for 10min, heating to 65 ℃, performing heat preservation and etherification for 100min, cooling to 40 ℃ after the reaction time, adding 13.5kg of natamycin, sodium citrate and PVA micropowder reagent mixed according to a ratio of 1: 10: 16 into the reaction kettle, stirring and reacting for 15min, discharging, crushing and packaging to obtain a finished product, comparative example 7 sample was obtained.

The starch composition products obtained in examples 1 to 5 and comparative examples 1 to 7 are subjected to various physical and chemical index tests, and the specific data are as follows:

firstly, the performance indexes of the products of all the embodiments are as follows:

secondly, various comparative product performance indexes are as follows:

as can be seen from a comparison of the data in the above two tables, the index of the starch obtained in comparative example 6 is not ideal enough in terms of fineness, because of the mismatch in the amount of etherification. The data for comparative examples 2-7 are clearly inferior to the examples, except for comparative example 1, in terms of the number of times the freeze-thaw did not evolve water. However, the wet process adopted in comparative example 1 is not as environmentally friendly and economical as the semi-dry process.

The data for each example is also significantly better than for each comparative example in terms of tack. After analysis and testing, we believe that the reason for this is:

comparative example 1: a sample prepared by single organic solvent carboxymethyl etherification reaction has higher substitution degree and water solubility, but the viscosity is not too high generally under the condition of no special treatment.

Comparative example 2: the process uses monochloroacetic acid for the etherification addition, requiring a larger amount of base to support the substitution reaction. It is evident that the process does not have enough base to participate in both the reaction with monochloroacetic acid and the catalysis.

Comparative example 3: without the addition of nanoparticles, the modification treatment of the starch surface was difficult to achieve as desired, resulting in that the effects of the examples were difficult to achieve despite the increase in viscosity.

Comparative example 4: the effective concentration reduction and protection treatment of the radical enhancer is carried out without adding a characteristic improver, which obviously causes that the utilization efficiency of the radical enhancer is greatly reduced.

Comparative example 5: with the excessive addition of the nano particles and the change of insufficient dosage of the alkali catalyst, the cold water solubility of the starch is obviously deteriorated, and the powder shows that the dust is increased, the environment is deteriorated, the water solubility of the product cannot be realized, and the viscosity is not high.

Comparative example 6: with the increase of the dosage of the etherification reagent, the method breaks through the effect that other reagents are required for etherification to coordinate, so that the etherification efficiency is low, the viscosity is not obviously increased, the substitution degree is increased, powder is not dispersed, particles are rough and difficult to unload, and the like, and has the following problems: along with the increase of the group strengthening reaction time, the activity of the reagent on the upper hydroxyl groups of main and branched chains of starch molecular groups is inhibited, a product with higher viscosity is difficult to obtain, and the water solubility of the starch is obviously poor.

In addition, in order to verify the cold water solubility of the starch obtained in each example and the starch obtained in the comparative example, the group of the present invention dissolved each starch sample with deionized water according to a certain process to form different glue solutions, and prepared the states of the starch glue forming samples of the different examples. (preparation method comprises dissolving 10 g of dried starch in 250mL beaker in deionized water to 200g to obtain 5% starch glue solution, stirring for 30min, standing to observe gel state after dissolution)

The front light after gelling for each sample is shown in FIG. 1. As can be seen from fig. 1-2 and the later comprehensive evaluation, the samples of the examples are soluble in cold water, the solution is relatively balanced and stable, while the samples of the comparative examples are generally relatively poor in cold water solubility, the starch does not dissolve and sink, and the delamination partially occurs (the sealing effect photographed by the photograph may not be very clear and can be clearly observed in practice because the starch is also white), especially in the comparative example 5, the delamination occurs obviously in a short time.

Using the starches obtained in the examples and comparative examples, a wallpaper glue was prepared according to the following formulation:

760g of deionized water, 200g of sample starch, 8g of VAE emulsion, 30g of titanium dioxide and 2g of preservative

The preparation process comprises the following steps: firstly, adding metered deionized water into a stirrer, starting stirring, sequentially adding the preservative, the titanium dioxide and the VAE emulsion, then slowly adding metered starch, timing and stirring for 30min to form the adhesive.

The data for the resulting wallpaper glue product are as follows:

as can be seen by comparing the data in the table above, the products obtained in examples 1-5 had significantly better scores than comparative examples 2-7 on a total scale. Although the score of comparative example 1 is also high, it is not suitable for popularization using a conventional wet process.

The raw materials and equipment used in the invention are common raw materials and equipment in the field if not specified; the methods used in the present invention are conventional in the art unless otherwise specified.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and all simple modifications, alterations and equivalents of the above embodiments according to the technical spirit of the present invention are still within the protection scope of the technical solution of the present invention.

Claims

1. A semi-dry preparation method of modified starch for wallpaper glue rich in nanoparticles is characterized by comprising the following steps:

1) mixing and pre-alkalizing: stirring the starch raw material, sequentially adding the nano particles and the alkali catalyst, and mixing and stirring; the nano particles are one or more of nano titanium dioxide, nano silicon dioxide and nano titanium trioxide;

2) dispersing and activating treatment: adding a dispersing activating agent into the product obtained in the step 1), performing molecular activation modification treatment at 15-50 ℃ for 5-60min, and controlling the water content of the treated starch to be 15-30 wt%; the dispersing activator is a mixture of one or more of fatty alcohol polyether sulfate, isopropanol, PEG-400 and fatty alcohol polyoxyethylene ether and water;

3) group strengthening reaction: adding a mixture of a characteristic improver and a radical enhancer into the product obtained in the step 2), and carrying out radical enhancement reaction for 10-60min at the temperature of 20-60 ℃; the group enhancer is one or more of adipic acid acetic anhydride mixture, dimethylol urea, cyanuric chloride and 3-chloro-1, 2-epoxypropane; the characteristic improving agent is one or more of carbon tetrachloride, ethanol, chloroform and isopropanol;

4) carboxymethyl etherification reaction: adding a carboxymethyl etherifying agent into the product obtained in the step 2), and carrying out carboxymethyl bimolecular displacement etherification reaction for 30-200min at the temperature of 50-90 ℃;

5) and (3) synergistic treatment: cooling the product obtained in the step 2), adding a synergistic additive for reaction, discharging, crushing, sieving and packaging to obtain a finished product; the synergistic auxiliary agent is one or more of VAE, PVAC, PVA micro powder, citric acid, fumaric acid, oxalic acid, sodium benzoate, natamycin and bronopol.

2. The semi-dry preparation method of modified starch for wallpaper glue rich in nanoparticles as claimed in claim 1, wherein in step 1), the starch material is selected from one or more of waxy corn starch, tapioca starch, corn starch, potato starch, and wheat starch.

3. The semi-dry preparation method of modified starch for wallpaper glue rich in nanoparticles as claimed in claim 1, wherein in step 1), the nanoparticles are selected from one or more of nanometer titanium dioxide, nanometer silicon dioxide and nanometer titanium tetroxide with particle size of 10-40 nm; the dosage of the nano particles is 0.01-1% of the mass of the starch raw material.

4. The semi-dry preparation method of modified starch for wallpaper glue rich in nanoparticles as claimed in claim 1, wherein in step 1), the alkali catalyst is selected from one or more of triethanolamine, sodium metasilicate, sodium hydroxide, sodium aluminate, potassium hydroxide, calcium hydroxide, sodium carbonate, disodium hydrogen phosphate; the amount of the catalyst is 3-8% of the mass of the starch raw material; mixing and stirring for 5-60 min.

5. The semi-dry preparation method of modified starch for wallpaper glue rich in nanoparticles as claimed in claim 1, wherein in step 2), the amount of dispersing activator is 5-25% of the mass of starch raw material, and the concentration of dispersing activator is 60-90 wt%; the reaction temperature is preferably 20-45 deg.C and the reaction time is 10-50 min.

6. The semi-dry preparation method of modified starch for wallpaper glue rich in nanoparticles as claimed in one of claims 1 to 5, wherein in step 3), the amount of the mixture of property improving agent and group strengthening agent is 0.005-2% of the starch material; the mass ratio of the characteristic improver to the group enhancer is 5-15: 1.

7. The semi-dry preparation method of modified starch for wallpaper glue rich in nanoparticles as claimed in claim 6, wherein in step 3), the reaction temperature is 25-50 ℃ for 15-60 min.

8. The semi-dry preparation method of modified starch for wallpaper glue rich in nanoparticles as claimed in claim 1, wherein the etherification reaction in step 4) is carried out at 50-90 ℃ for 40-180 min.

9. The semi-dry preparation method of modified starch for wallpaper glue rich in nanoparticles as claimed in claim 1 or 8, wherein in step 4), the carboxymethyl etherifying agent is prepared by: mixing monochloroacetic acid and an alkaline reagent according to the mass ratio of = 1: 0.3-0.98, reacting for 30-200min at 20-90 ℃, sealing and packaging for later use; the dosage of the carboxymethyl etherifying agent is 8-30% of the mass of the starch raw material.

10. The semi-dry preparation method of modified starch for wallpaper glue rich in nanoparticles as claimed in claim 1, wherein in step 5), the amount of the synergist is 0.5-3.5% of the starch raw material, the reaction temperature is 40-60 ℃, and the reaction time is 10-60 min.