CN111286286B - Preparation method of water-resistant starch adhesive - Google Patents
Preparation method of water-resistant starch adhesive Download PDFInfo
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- CN111286286B CN111286286B CN202010236013.4A CN202010236013A CN111286286B CN 111286286 B CN111286286 B CN 111286286B CN 202010236013 A CN202010236013 A CN 202010236013A CN 111286286 B CN111286286 B CN 111286286B
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
- C09J103/00—Adhesives based on starch, amylose or amylopectin or on their derivatives or degradation products
- C09J103/04—Starch derivatives
- C09J103/08—Ethers
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
- B01J19/26—Nozzle-type reactors, i.e. the distribution of the initial reactants within the reactor is effected by their introduction or injection through nozzles
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08B—POLYSACCHARIDES; DERIVATIVES THEREOF
- C08B31/00—Preparation of derivatives of starch
- C08B31/08—Ethers
- C08B31/12—Ethers having alkyl or cycloalkyl radicals substituted by heteroatoms, e.g. hydroxyalkyl or carboxyalkyl starch
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
- C09J11/00—Features of adhesives not provided for in group C09J9/00, e.g. additives
- C09J11/02—Non-macromolecular additives
- C09J11/04—Non-macromolecular additives inorganic
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K3/00—Use of inorganic substances as compounding ingredients
- C08K3/32—Phosphorus-containing compounds
- C08K2003/321—Phosphates
- C08K2003/324—Alkali metal phosphate
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K2201/00—Specific properties of additives
- C08K2201/014—Additives containing two or more different additives of the same subgroup in C08K
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L2312/00—Crosslinking
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- Life Sciences & Earth Sciences (AREA)
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Abstract
The invention provides a preparation method of a water-resistant starch adhesive, which comprises the following steps: an external circulation spray type reactor is used, and an external circulation pump is used for high-speed circulation spraying in the reaction process; firstly, adding water and starch into a reactor, fully mixing, feeding a sodium hydroxide solution from a first feeding hole, and spraying the sodium hydroxide solution into the reactor; sequentially adding polyvinyl alcohol solution, cross-linking agent and ferrous sulfate powder; and finally, slowly introducing methane chloride gas from a second feed inlet, continuously and circularly spraying at a high speed to realize full mixing, and continuously and circularly spraying for 1-2 hours at a heat preservation state after the feeding is finished, thus finishing the reaction. The invention adopts the external circulation spray type reactor, promotes the mass transfer rate in the reaction system, and has more uniform concentration distribution; methyl chloride gas is added for reaction, so that methyl etherification end capping is realized, and the water resistance of the adhesive is greatly improved; a plurality of boron-free crosslinking agents are applied, so that the safety of industrial production is improved.
Description
Technical Field
The invention relates to the technical field of adhesive preparation, in particular to a preparation method of a starch adhesive with good water resistance.
Background
With the progress of society and the development of industry, adhesives are widely applied to the fields of mechanical processing, construction, food packaging, medical health, aerospace science and technology, wood processing and the like, and products are continuously developed towards high performance, resource conservation, environmental friendliness and diversified varieties.
Starch is a renewable and biodegradable natural plant material, and has the characteristics of low cost, convenient processing and preparation, no pungent smell and the like. Because the starch adhesive has a plurality of excellent characteristics, the development of the environment-friendly adhesive such as the starch-based adhesive has huge market potential. However, starch molecular chains have a large number of glycosidic bonds and hydroxyl groups, and adhesives prepared from the starch molecular chains generally have the defects of poor water resistance, poor storage stability, low bonding strength and the like, so that the rapid development of the adhesives is severely restricted. In addition, a borax cross-linking agent is generally added in the traditional preparation process for producing the starch adhesive to increase the bonding strength, but borax is toxic and has certain harm to the health of workers.
Therefore, a starch adhesive with no boron, low toxicity and good water resistance is needed.
Disclosure of Invention
An object of the present invention is to solve at least the above problems and disadvantages and to provide at least the advantages described hereinafter.
It is still another object of the present invention to improve the reaction efficiency and form a starch adhesive with uniform concentration distribution by using an external circulation spray type reactor.
The invention also aims to realize methyl etherification end capping by using the reaction of methane chloride and hydroxyl, thereby avoiding the reaction of the hydroxyl and water, being difficult to mildew and having good water resistance.
In order to achieve these objects and other advantages in accordance with the present invention, a water-resistant starch adhesive is provided, wherein the raw materials comprise, in parts by weight: 100 parts of starch, 300-400 parts of water, 10-20 parts of sodium hydroxide solution, 50-100 parts of polyvinyl alcohol solution, 1-2 parts of cross-linking agent, 0.5 part of ferrous sulfate and 5-15 parts of methane chloride;
the preparation method comprises the following specific steps:
the method comprises the following steps: adding water and starch into the external circulation spray type reactor, and starting an external circulation pump to perform high-speed circulation spraying;
step two: feeding sodium hydroxide solution from a first feeding hole, and spraying the sodium hydroxide solution into a reactor;
step three: sequentially adding polyvinyl alcohol solution, cross-linking agent and ferrous sulfate powder;
step four: slowly introducing methane chloride gas from a second feed inlet, continuously and circularly spraying at high speed to realize full mixing, feeding and spraying for 2-3 hours, continuously and circularly spraying for 1-2 hours at a constant temperature after feeding is finished, and finishing the reaction;
preferably, the starch raw material is one or a mixture of more of corn starch, tapioca starch and potato starch.
Preferably, the cross-linking agent is one or a mixture of more of sodium tripolyphosphate, ferric trichloride and alum.
Preferably, the content of the polyvinyl alcohol solution is 5-10%.
Preferably, the concentration of the sodium hydroxide solution is 10%.
Preferably, the temperature during the reaction in the second to fourth steps is controlled to be from room temperature to 60 ℃.
Preferably, wherein the starch is corn starch.
The invention at least comprises the following beneficial effects: because the external circulation spray type reactor is adopted to replace the traditional stirred tank reactor, the mass transfer rate in the reaction system is greatly promoted, the concentration distribution is more uniform, and the probability of side reaction is reduced; because the addition reaction of methane chloride gas is adopted, the methyl etherification end capping of the hydroxyl on the surface is realized through the reaction with methane chloride, so that the water resistance of the adhesive is greatly improved; because a plurality of boron-free crosslinking agents are applied in the reaction process, the safety of industrial production is improved.
Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention.
Drawings
FIG. 1 is a schematic structural view of an external circulation spray reactor provided in the examples.
Reference numerals: 1. an external circulation spray type reactor; 2. a second feed port; 3. a first feed port; 4. pump and method of operating the same
Detailed Description
The present invention is further described in detail below with reference to the attached drawings so that those skilled in the art can implement the invention by referring to the description text.
It will be understood that terms such as "having," "including," and "comprising," as used herein, do not preclude the presence or addition of one or more other elements or groups thereof.
To illustrate the effects of the present invention, the inventors provide comparative experiments as follows:
example 1
The method comprises the following steps: adding 400 parts of water and 100 parts of cassava starch into an external circulation spray type reactor (1) shown in figure 1, and starting an external circulation pump (4) to carry out high-speed circulation spraying;
step two: controlling the reaction temperature to be 60 ℃, feeding 20 parts of 10% sodium hydroxide solution from a first feeding hole (3), and spraying into a reactor;
step three: adding 50 parts of 10% polyvinyl alcohol solution; adding 2 parts of sodium tripolyphosphate and 0.5 part of ferrous sulfate powder;
step four: slowly adding 15 parts of methane chloride gas from a second feed port (2), and realizing full mixing reaction through an external circulation spray type reactor; the feeding and spraying time is 2 hours, and after the feeding is finished, the thermal-insulation circulating spraying reaction is continued for 1 hour, and the reaction is finished;
example 2
The method comprises the following steps: adding 350 parts of water and 100 parts of potato starch into an external circulation spray type reactor (1) shown in figure 1, and starting an external circulation pump (4) to carry out high-speed circulation spraying;
step two: controlling the reaction temperature to be 40 ℃, feeding 15 parts of 10% sodium hydroxide solution from a first feeding hole (3), and spraying into a reactor;
step three: adding 75 parts of 8% polyvinyl alcohol solution; adding 1.5 parts of ferric trichloride and 0.5 part of ferrous sulfate powder;
step four: slowly adding 10 parts of methane chloride gas from a second feed port (2), and realizing full mixing reaction through an external circulation spray type reactor; the feeding and spraying time is 2 hours, and after the feeding is finished, the thermal-insulation circulating spraying reaction is continued for 2 hours, and the reaction is finished;
example 3
The method comprises the following steps: adding 300 parts of water and 100 parts of corn starch into an external circulation spray type reactor (1) shown in figure 1, and starting an external circulation pump (4) to carry out high-speed circulation spraying;
step two: controlling the reaction temperature to be 40 ℃, feeding 15 parts of 10% sodium hydroxide solution from a first feeding hole (3), and spraying into a reactor;
step three: adding 100 parts of 5% polyvinyl alcohol solution; adding 1.3 parts of alum and 0.5 part of ferrous sulfate powder;
step four: slowly adding 10 parts of methane chloride gas from a second feed port (2), and realizing full mixing reaction through an external circulation spray type reactor; the feeding and spraying time is 3 hours, and after the feeding is finished, the thermal-insulation circulating spraying reaction is continued for 1 hour, and the reaction is finished;
comparative example
The method comprises the following steps: adding 300 parts of water and 100 parts of corn starch into an external circulation spray type reactor (1) shown in figure 1, and starting an external circulation pump (4) to carry out high-speed circulation spraying;
step two: controlling the reaction temperature to be room temperature, feeding 10 parts of 10% sodium hydroxide solution from a first feeding hole (3), and spraying the solution into a reactor;
step three: adding 100 parts of 5% polyvinyl alcohol solution; adding 1 part of borax and 0.5 part of ferrous sulfate powder;
step four: slowly adding 5 parts of methane chloride gas from a second feeding hole (2), and realizing full mixing reaction through an external circulation spray type reactor; the feeding and spraying time is 3 hours, and after the feeding is finished, the thermal-insulation circulating spraying reaction is continued for 2 hours, and the reaction is finished;
the products obtained in the examples and the comparative examples are verified by experiments such as a viscosity test, an initial adhesion time test, a water resistance experiment and the like:
[ Table 1]
Since the above examples and comparative examples were tested with 100 parts of different starches and the best ratio of other components, as can be seen from table 1 above, in example 3 and comparative example, with the same 100 parts of corn starch and different cross-linking agents, the starch adhesive obtained using alum as the cross-linking agent has a lower gelatinization temperature, lower viscosity, shorter initial adhesion time, stronger adhesive strength, and greatly increased water resistance time than the starch adhesive obtained using borax as the cross-linking agent.
During high-speed production, the gelatinization temperature has a great influence on the bonding quality, and when a machine is accelerated, if the gelatinization temperature of the adhesive is higher, the adhesive cannot be fully gelatinized, the bonding force is reduced, and degumming is caused. In comparative examples 1 to 3, it can be seen that example 3 has a lower gelatinization temperature and is easily gelatinized during production and processing.
When the viscosity of the starch adhesive is too high, the fluidity of the adhesive is poor, the contact and infiltration of the adhesive on the surface of an adherend are hindered, the permeability is poor, the acting force between the adhesive and the adherend is reduced, the adhesive strength is affected, and the adhesive amount is unevenly coated; and for suspension such as starch adhesive, the viscosity is reduced, and the viscosity stability is improved. Comparing examples 1-3 with the comparative example, it can be seen that the viscosity of the examples is reduced, which results in an improved viscosity stability of the starch adhesive.
From the performance tests of the initial adhesion time, the adhesive strength, the water-resistant time and the like, the comparative examples 1 to 3 and the comparative examples can find that the initial adhesion time of the examples is reduced, the adhesive strength is increased and the water-resistant time is greatly increased.
From a comparison of examples 1, 2, 3 with each other, it can be seen that example 3, using 300 parts water, 100 parts corn starch, 15 parts sodium hydroxide, 100 parts polyvinyl alcohol solution, 1.3 parts alum and 0.5 ferrous sulfate powder, is optimal with the shortest tack time, the highest cohesive strength and the longest water resistance time.
Therefore, the invention adopts a unique external circulation spray type reactor to replace the traditional stirred tank type reactor. By spraying and mixing the raw materials of starch, water and sodium hydroxide solution and the like on the upper part of the reactor, a large amount of tiny droplet particles are formed, at the same time, the methane chloride as gas can quickly contact with the small drops on the upper part of the reactor, the grain diameter of the sprayed small drops is extremely small, thereby having extremely large specific surface area, can be rapidly contacted with the methane chloride in the gas phase and rapidly absorbed into small liquid drops, thereby greatly promoting the mass transfer process among all the reaction species in the reaction system, improving the mass transfer rate of the external circulation spray type reactor by more than one order of magnitude compared with the mass transfer rate of the traditional stirred tank type reactor, greatly promoting the mass transfer among all the reaction species in the reactor, therefore, the reaction can be in kinetic control, the reaction efficiency is greatly improved in the rapid mass transfer process in the reaction system, and the occurrence of side reactions is reduced. Meanwhile, the rapid mass transfer in the liquid drops also ensures the uniformity of the content concentration of each small liquid drop, and the uniformity of the concentration distribution in the stirring kettle is greatly improved, so that the occurrence probability of side reaction is further reduced, and the selectivity and the efficiency of the reaction are improved.
In the reaction, starch and polyvinyl alcohol react with liquid caustic soda and methane chloride, and simultaneously, a cross-linking agent is added, so that polymer macromolecular groups form cross-linking, the adhesive force of the product is improved, and the hydroxyl groups on the surface realize methyl etherification end capping through the methane chloride, thereby greatly improving the water resistance of the adhesive.
In the reaction, a plurality of boron-free crosslinking agents are applied, and the boron-free crosslinking agent has better performance and water-resistant time.
In the reaction, a methyl etherified starch system is developed, so that the gelatinization temperature of the product is greatly reduced, the viscosity of the product is reduced, the viscosity stability of the product is improved, the binding power of the product is improved, and the product has an excellent binding effect.
While embodiments of the invention have been disclosed above, it is not intended to be limited to the uses set forth in the specification and examples. It can be applied to all kinds of fields suitable for the present invention. Additional modifications will readily occur to those skilled in the art. It is therefore intended that the invention not be limited to the exact details and illustrations described and illustrated herein, but fall within the scope of the appended claims and equivalents thereof.
Claims (5)
1. A preparation method of a water-resistant starch adhesive is characterized by comprising the following steps:
the raw materials comprise the following components in parts by weight: 100 parts of starch, 300-400 parts of water, 10-20 parts of sodium hydroxide solution, 50-100 parts of polyvinyl alcohol solution, l-2 parts of cross-linking agent, 0.5 part of ferrous sulfate and 5-15 parts of methane chloride; the cross-linking agent is one or a mixture of sodium tripolyphosphate and alum;
the preparation method comprises the following specific steps:
the method comprises the following steps: adding water and starch into the external circulation spray type reactor, and starting an external circulation pump to perform high-speed circulation spraying;
step two: feeding sodium hydroxide solution from a first feeding hole, and spraying the sodium hydroxide solution into a reactor;
step three: sequentially adding polyvinyl alcohol solution, cross-linking agent and ferrous sulfate powder;
step four: and slowly introducing methane chloride gas from a second feed port, continuously and circularly spraying at a high speed to realize full mixing, feeding and spraying for 2-3 hours, continuously and circularly spraying for l-2 hours at a heat preservation state after feeding is finished, and finishing the reaction.
2. The preparation method of the water-resistant starch adhesive according to claim I, wherein the starch material is one or a mixture of corn starch, tapioca starch and potato starch.
3. The method of claim i, wherein the concentration of the sodium hydroxide solution is 10%.
4. The preparation method of the water-resistant starch adhesive according to claim I, wherein the content of the polyvinyl alcohol solution is 5-10%.
5. The method for preparing water-resistant starch adhesive according to claim I, wherein the temperature of the reaction in the second step to the fourth step is controlled to be between room temperature and 60 ℃.
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