CN108059376B - A kind of preparation method of dental model plaster - Google Patents

Abstract

The invention provides a preparation method of dental model gypsum. The high-purity and high-whiteness α-type hemihydrate gypsum powder obtained by a liquid phase method is prepared in 100 parts, 15-20 parts of a reinforcing agent, 10-12 parts of a toughening agent, 8-10 parts of grinding agent, 6-8 parts of water reducing agent, and 3-5 parts of defoaming agent are mixed and stirred to form a mold, wherein the reinforcing agent is cyanoacrylate, and the toughening agent is polypropylene resin and fiber, the antiwear agent is a copolymer of butadiene and acrylonitrile, the water reducing agent is a naphthalene-based superplasticizer and melamine, and the defoaming agent is a D-30X high-efficiency defoaming agent. The invention provides a preparation method of dental model gypsum, adopts new formula and dosage, improves the defect of the original dental gypsum with small strength and hardness, and simultaneously improves the toughness and wear resistance of the finished gypsum.

Description

A kind of preparation method of dental model plaster

technical field

The invention relates to a plaster, in particular to a preparation method of a dental model plaster.

Background technique

Dental plaster is an indispensable replica model material in the process of dentist diagnosis, clinical operation and treatment. It enables dentists to diagnose and treat patients outside the mouth. It is an important medical material. Medical dental gypsum has higher requirements on the hardness, density and strength of gypsum, and the performance of the existing dental gypsum is difficult to meet the requirements.

The invention patent of application number 201210000045.X, "a high-strength gypsum for dental use", discloses a dental gypsum, the composition of which is 100 parts of α-hemihydrate gypsum powder; 3 to 10 parts of reinforcing agent; 2 to 10 parts of water reducing agent 7 parts; 0 to 5 parts of cement are evenly mixed. The invention adopts the method of adding additives to common α-hemihydrate gypsum to improve the solidification performance of gypsum, and improves the density, strength and hardness of gypsum. However, the gypsum still has insufficient properties, the strength and hardness of the finished gypsum gypsum are still not large enough, and the toughness and wear resistance of the finished gypsum product cannot meet the requirements.

SUMMARY OF THE INVENTION

The object of the present invention is to overcome the defects of the prior art, provide a preparation method of dental model plaster, adopt a new formula and dosage, improve the original dental plaster strength and hardness small defects, while the toughness and hardness of the finished plaster are improved. Anti-wear properties are improved.

The present invention is realized in this way:

The invention provides a preparation method of dental model plaster, comprising the following steps:

Step 1. Purification treatment: prepare phosphogypsum into a slurry with a solid content of 5% to 60%, filter out large impurities and suspended solids with a screen, add dilute sulfuric acid (1 to 12M) for neutralization reaction, and remove a small amount of insoluble The oxides, calcium carbonate, magnesium carbonate and other impurities are converted into soluble salts, and the organic carbon is filtered out. After adding quicklime for neutralization, it is crushed and ground into gypsum with a fineness and particle distribution D50 between 20-50um pink;

Step 2. Crystallization reaction: place the gypsum powder in a mud mixer, add it into an aqueous solution containing sulfuric acid and a mixed acid of phosphoric acid in a ratio of 1:8 to a solid-to-liquid ratio, and mix evenly to prepare a mixed slurry, wherein the sulfuric acid is The mass of phosphoric acid accounts for 8-10% of the total mass of the mixed acid aqueous solution in terms of H2SO4, and the quality of phosphoric acid accounts for 18-20% of the total mass of the mixed acid aqueous solution in terms of P2O5, and then adds 0.1-5% of the crystallizing agent, and the crystallizing agent includes A mixture of sodium citrate, potassium glutarate, magnesium succinate and inorganic salts, followed by adding sodium acetate with a mass percentage of 1% to 6% as an admixture to form a supersaturated solution system. Crystallization reaction, the conversion reaction time is 4～16h;

Step 3, directional crystallization: add 0.1% crystal form control agent to the mixed slurry, stir evenly, carry out directional crystallization, and conduct directional crystallization for 1 to 4 hours to obtain a mixed solution containing α-type hemihydrate gypsum, and the crystal form is controlled Agents include fumaric acid, fatty acids and surfactants;

Step 4, separation by liquid phase method: solid-liquid separation of the mixed liquid containing α-type hemihydrate gypsum obtained in step 3 to obtain solid phase A and liquid phase B, and liquid phase B is recycled;

Step 5, washing and separation: the solid phase A and the liquid phase B obtained in the step 4 are mixed to carry out a cyclic crystallisation reaction, and the solid phase A is washed with hot water at 80-100°C to obtain the solid phase C and the liquid phase D; Liquid phase D is used to dilute concentrated sulfuric acid to provide sulfuric acid solution, and solid phase C is dried to obtain pure α-type hemihydrate gypsum crystals.

Step 6, drying and grinding: the pure α-type hemihydrate gypsum crystals obtained in the step 5 are dried at 120-170° C., and then ground according to the application fineness after drying to obtain high-purity and high-brightness α-type gypsum. Hemihydrate gypsum powder.

Step 7. Prepare dental model gypsum raw materials: reinforcing agent, toughening agent, anti-wear agent, water reducing agent, defoamer and α-type hemihydrate gypsum powder obtained in step 11, the dental model gypsum raw materials and parts by weight The numbers are: 100 parts of α-type hemihydrate gypsum powder, 15-20 parts of reinforcing agent, 10-12 parts of toughening agent, 8-10 parts of anti-wear agent, 6-8 parts of water reducing agent, 3-5 parts of defoamer wherein, the reinforcing agent is cyanoacrylate, the toughening agent is polypropylene resin and fiber, the antiwear agent is a copolymer of butadiene and acrylonitrile, and the water reducing agent is naphthalene series High-efficiency water reducing agent and melamine, the defoamer is D-30X high-efficiency defoamer.

Step 8. Stirring: add an appropriate amount of water, stir by hand for 30-40 seconds or stir by hand for 10-15 seconds and then vacuum for 20-30 seconds;

Step 9. Molding: Pour the finished product after vacuum stirring into the impression to copy the model, let it stand for 10-15 minutes and wait for it to solidify and then remove.

The present invention has the following beneficial effects:

The present invention provides a preparation method of dental model gypsum, which adopts new formula and dosage. The raw materials and parts by weight of the dental model gypsum are: 100 parts of α-type hemihydrate gypsum powder, 15-20 parts of reinforcing agent, 10-12 parts of toughness agent, 8-10 parts of anti-wear agent, 6-8 parts of water reducing agent, 3-5 parts of defoamer, improve the original strength and hardness of dental gypsum, and at the same time the toughness of the finished gypsum and anti-wear properties are improved.

Description of drawings

FIG. 1 is a process flow diagram of a method for preparing a dental model plaster provided by an embodiment of the present invention.

Detailed ways

Example 1

As shown in FIG. 1, an embodiment of the present invention provides a preparation method of dental model plaster, comprising the following steps:

Step 1. Purification treatment: prepare phosphogypsum into a slurry with a solid content of 5% to 60%, filter out large impurities and suspended solids with a screen, add dilute sulfuric acid (1 to 12M) for neutralization reaction, and remove a small amount of insoluble The oxides, calcium carbonate, magnesium carbonate and other impurities are converted into soluble salts, and the organic carbon is filtered out. After adding quicklime for neutralization, it is crushed and ground into gypsum with a fineness and particle distribution D50 between 20-50um pink;

Step 2. Crystallization reaction: put the gypsum powder in a mud mixer, add it into an aqueous solution containing sulfuric acid and phosphoric acid in a ratio of 1:8 to a solid-to-liquid ratio, and mix evenly to prepare a mixed slurry, wherein The mass of sulfuric acid, calculated as H2SO4, accounts for 9.00% of the mixed acid, the mass of phosphoric acid, calculated as P2O5, accounts for 20.00% of the mixed acid, and the added water accounts for 34.79% of the mixed acid aqueous solution. Crystallizing agent, stir evenly, and carry out crystallizing reaction at 100 ° C for 3 hours to obtain a mixed solution containing α-type hemihydrate gypsum. The crystallizing agent is a mixture of sodium sulfate, sodium citrate, potassium glutarate, and magnesium succinate. In the mixture, the addition of sodium sulfate accounts for 0.2% of the total mass of the mixed acid aqueous solution, the addition of sodium citrate accounts for 0.1% of the total mass of the mixed acid aqueous solution, the addition of potassium glutarate accounts for 0.1% of the total mass of the mixed acid aqueous solution, and succinic acid The added amount of magnesium accounts for 0.1% of the total mass of the mixed acid aqueous solution.

Step 3, directional crystallization: add 0.1% crystal form control agent to the mixed slurry, stir evenly, carry out directional crystallization, and conduct directional crystallization for 1 to 4 hours to obtain a mixed solution containing α-type hemihydrate gypsum, and the crystal form is controlled Agents include 40% fumaric acid, 50% fatty acid, and 10% sodium dodecylbenzenesulfonate;

Step 4, separation by liquid phase method: solid-liquid separation of the mixed liquid containing α-type hemihydrate gypsum obtained in step 3 to obtain solid phase A and liquid phase B, and liquid phase B is recycled;

Step 5, washing and separation: the solid phase A and the liquid phase B obtained in the step 4 are mixed to carry out a cyclic crystallisation reaction, and the solid phase A is washed with hot water at 80-100°C to obtain the solid phase C and the liquid phase D; Liquid phase D is used to dilute concentrated sulfuric acid to provide sulfuric acid solution, and solid phase C is dried to obtain pure α-type hemihydrate gypsum crystals.

The obtained pure α-type hemihydrate gypsum crystals were tested for related properties:

The α-type hemihydrate gypsum product obtained in Example 1 complies with the industry standard of JC/T2038-2010, and is in the form of a hexagonal short column under a 200-fold optical microscope. The compressive strength is 120MPa, the initial setting is 7 minutes, and the final setting is 15 minutes.

Step 6, drying and grinding: the pure α-type hemihydrate gypsum crystals obtained in the step 5 are dried at 120-170° C., and then ground according to the application fineness after drying to obtain high-purity and high-brightness α-type gypsum. Hemihydrate gypsum powder.

Step 7. Prepare dental model gypsum raw materials: reinforcing agent, toughening agent, anti-wear agent, water reducing agent, defoamer and α-type hemihydrate gypsum powder obtained in step 11, the dental model gypsum raw materials and parts by weight The numbers are: 100 parts of α-type hemihydrate gypsum powder, 20 parts of reinforcing agent, 12 parts of toughening agent, 10 parts of anti-wear agent, 8 parts of water reducing agent, and 5 parts of defoamer, wherein the reinforcing agent is cyanide acrylic acid salt, the toughening agent is polypropylene resin and fiber, the anti-wear agent is a copolymer of butadiene and acrylonitrile, the water reducing agent is a naphthalene-based superplasticizer and melamine, and the The foaming agent is D-30X high-efficiency defoaming agent.

Step 8. Stirring: add an appropriate amount of water, stir by hand for 30-40 seconds or stir by hand for 10-15 seconds and then vacuum for 20-30 seconds;

Step 9. Molding: Pour the finished product after vacuum stirring into the impression to copy the model, let it stand for 10-15 minutes and wait for it to solidify and then remove.

Example 2

In an embodiment of the present invention, a method for preparing a dental model plaster is provided. Steps 1-6 and steps 8-9 are the same as those in Embodiment 1, except that:

Step 7. Prepare dental model gypsum raw materials: reinforcing agent, toughening agent, anti-wear agent, water reducing agent, defoamer and α-type hemihydrate gypsum powder obtained in step 11, the dental model gypsum raw materials and parts by weight The numbers are: 100 parts of α-type hemihydrate gypsum powder, 15 parts of reinforcing agent, 10 parts of toughening agent, 8 parts of anti-wear agent, 6 parts of water reducing agent, and 3 parts of defoamer, wherein the reinforcing agent is Cyanoacrylate, the toughening agent is polypropylene resin and fiber, the anti-wear agent is a copolymer of butadiene and acrylonitrile, the water reducing agent is a naphthalene-based superplasticizer and melamine, the The defoamer is D-30X high-efficiency defoamer.

Example 3

In an embodiment of the present invention, a method for preparing a dental model plaster is provided. Steps 1-6 and steps 8-9 are the same as those in Embodiment 1, except that:

Step 7. Prepare dental model gypsum raw materials: reinforcing agent, toughening agent, anti-wear agent, water reducing agent, defoamer and α-type hemihydrate gypsum powder obtained in step 11, the dental model gypsum raw materials and parts by weight The numbers are: 100 parts of α-type hemihydrate gypsum powder, 18 parts of reinforcing agent, 11 parts of toughening agent, 9 parts of anti-wear agent, 7 parts of water reducing agent, and 4 parts of defoamer, wherein the reinforcing agent is Cyanoacrylate, the toughening agent is polypropylene resin and fiber, the anti-wear agent is a copolymer of butadiene and acrylonitrile, the water reducing agent is a naphthalene-based superplasticizer and melamine, the The defoamer is D-30X high-efficiency defoamer.

The dental model gypsum finished product in the above-mentioned embodiment 1, embodiment 2, and embodiment 3 is tested, and the existing dental gypsum is tested as a comparative example, and the performance is as shown in the following table:

project Compressive strength Flexural strength Relative wear resistance expansion rate curing time Example 1 62MPa 20MPa 1.064 0.1% 10-15min Example 2 70MPa 22MPa 1.014 0.1% 10-15min Example 3 65MPa 20MPa 1.004 0.1% 10-15min Comparative ratio 20MPa 10MPa 0.464 0.2% 15-20min

It can be seen that the compressive strength, flexural strength, wear resistance, expansion ratio and other indicators in the above three embodiments are greatly improved compared with the prior art, and the required moisture is also reduced accordingly, especially the expansion Compared with the prior art, the rate of gypsum is greatly reduced, which greatly reduces the expansion of gypsum during the production process, and facilitates the detachment of the gypsum mold.

Contents not described in detail in this specification belong to the prior art known to those skilled in the art.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of the present invention. within the scope of protection.

Claims (2)

1. A preparation method of dental model plaster is characterized by comprising the following steps:

step 1, purification treatment: preparing phosphogypsum into slurry with solid content of 5-60%, filtering out large impurities and suspended matters by using a screen, adding dilute sulfuric acid (1-12M) for neutralization reaction, removing a small amount of insoluble oxides, calcium carbonate, magnesium carbonate and other impurities to convert the impurities into soluble salt, filtering out organic carbon, adding quicklime for neutralization treatment, crushing and grinding into gypsum powder with fineness and particle distribution D50 between 20-50 um;

step 2, crystal transformation reaction: and (2) placing the gypsum powder into a slurry mixer, wherein the solid-to-liquid ratio is 1: 8, adding the sulfuric acid and the phosphoric acid into a mixed acid aqueous solution according to the proportion, and uniformly mixing to obtain mixed slurry, wherein the mass of the sulfuric acid is 8-10% of the total mass of the mixed acid aqueous solution in terms of H2SO4, the mass of the phosphoric acid is 18-20% of the total mass of the mixed acid aqueous solution in terms of P2O5, 0.1-5% of a crystal transformation agent is added, the crystal transformation agent comprises a mixture of sodium citrate, potassium glutarate, magnesium succinate and inorganic salts, and then 1-6% of sodium acetate in mass percentage is added as an additive to form a supersaturated solution system, the slurry is kept at 80-120 ℃ for crystal transformation reaction, and the transformation reaction time is 4-16 hours;

step 3, directional crystallization: adding 0.1% of crystal form control agent into the mixed slurry, uniformly stirring, carrying out directional crystallization for 1-4 h to obtain a mixed solution containing alpha-type semi-hydrated gypsum, wherein the crystal form control agent comprises fumaric acid, fatty acid and a surfactant;

and 4, separating by a liquid phase method: carrying out solid-liquid separation on the mixed solution containing the alpha-type semi-hydrated gypsum prepared in the step (3) to obtain a solid phase A and a liquid phase B, and recycling the liquid phase B;

step 5, washing and separating: mixing the solid phase A and the liquid phase B obtained in the step (4) for a circulating crystal transformation reaction, and washing the solid phase A with hot water at the temperature of 80-100 ℃ to obtain a solid phase C and a liquid phase D; the liquid phase D is used for diluting concentrated sulfuric acid to provide sulfuric acid solution, and the solid phase C is dried to obtain pure alpha-type semi-hydrated gypsum crystals;

step 6, drying and grinding: drying the pure alpha-type semi-hydrated gypsum crystal obtained in the step (5) at 120-170 ℃, drying and grinding according to application fineness to obtain high-purity high-whiteness alpha-type semi-hydrated gypsum powder;

step 7, preparing a dental model gypsum raw material: reinforcing agent, toughening agent, antiwear agent, water reducing agent, defoaming agent and the alpha-type semi-hydrated gypsum powder obtained in the step 6, wherein the dental model gypsum comprises the following raw materials in parts by weight: 100 parts of alpha-type semi-hydrated gypsum powder, 15-20 parts of a reinforcing agent, 10-12 parts of a toughening agent, 8-10 parts of an antiwear agent, 6-8 parts of a water reducing agent and 3-5 parts of a defoaming agent, wherein the reinforcing agent is cyanoacrylate, the toughening agent is polypropylene resin and fiber, the antiwear agent is a copolymer of butadiene and acrylonitrile, the water reducing agent is a naphthalene-based high-efficiency water reducing agent and melamine, and the defoaming agent is a D-30X high-efficiency defoaming agent;

step 8, stirring: adding water with a proper proportion, manually stirring for 30-40 seconds or manually stirring for 10-15 seconds, and then stirring in vacuum for 20-30 seconds;

step 9, molding: pouring the finished product after vacuum stirring into a die to reproduce the model, standing for 10-15 minutes, and removing after curing;

the inorganic salt in the step 2 is sodium sulfate, the addition amount of the sodium sulfate accounts for 0.2 percent of the total mass of the mixed acid aqueous solution, the addition amount of the sodium citrate accounts for 0.1 percent of the total mass of the mixed acid aqueous solution, the addition amount of the potassium glutarate accounts for 0.1 percent of the total mass of the mixed acid aqueous solution, and the addition amount of the magnesium succinate accounts for 0.1 percent of the total mass of the mixed acid aqueous solution;

the surfactant in the step 3 is sodium dodecyl benzene sulfonate, and the crystal form control agent comprises 40% of fumaric acid, 50% of fatty acid and 10% of sodium dodecyl benzene sulfonate.

2. The method of claim 1, wherein the fibers of step 7 are one or more of glass fibers, polyester fibers, or asbestos fibers.

Images