CN111268687A - A kind of organoclay composition and preparation method thereof - Google Patents

Abstract

The invention relates to an organic clay composition which can be used as a thickening rheological aid and can be used in the fields of paint, printing ink, oil field drilling and the like. An organoclay composition comprises montmorillonite, sepiolite and long chain alkyl quaternary ammonium salt. The organic clay composition mainly comprises montmorillonite, sepiolite and long-chain alkyl quaternary ammonium salt, and also comprises a small amount of organic auxiliary agent; and is prepared by a specific process. The organoclay composition modified by the process disclosed by the invention has the advantages of good dispersibility, good suspension property and good thickening property, and high rheological property, and can be effectively promoted to be applied to a low-polarity system.

Description

A kind of organoclay composition and preparation method thereof

technical field

The invention relates to an organoclay composition and a preparation method thereof. The organoclay composition can be used as a thickening rheological auxiliary, and can be used in the fields of paint, ink, oil field drilling and the like.

Background technique

Clay is an important mineral raw material that exists widely in nature and is generally formed by the weathering of aluminosilicate minerals on the earth's surface. Its main components are composed of a variety of hydrated silicates and a certain amount of alumina, alkali metal oxides and alkaline earth metal oxides, and contain impurities such as quartz, feldspar, mica, sulfate, sulfide, and carbonate. Clay minerals are generally small in size, often in the colloidal size range, crystalline or amorphous, most of them are lamellar, and a few are tubular or rod-shaped. Among the clay minerals, bentonite, sepiolite, attapulgite and kaolin are the most widely used. The microstructure of bentonite is mainly lamellar, and the microstructure of sepiolite and attapulgite is mainly rod-like or fibrous. Among them, the minerals with higher cation exchange capacity are bentonite and sepiolite.

Organoclays generally refer to organically modified clays. The surface of the clay particles changes from hydrophilic to hydrophobic. It can be widely used in fine chemical fields such as petroleum drilling fluids, coatings, inks, polymer nanocomposites, etc., as thickening rheological additives and functional additives.

The invention patent document with the application number of 201810060193.8 discloses a composite organoclay for oil-based drilling fluid and a compounding method thereof. The article provides the preparation of organic montmorillonite and fibrous organoclay, and the compounding of organic montmorillonite and fibrous organoclay in a certain proportion to prepare oil-based drilling fluid. Organomontmorillonite and fibrous organoclay were prepared separately and then compounded to improve temperature resistance in oil-based drilling fluid formulations.

The invention patent document with the patent number of 201310034512.5 discloses a preparation method of modified organic bentonite. It is mentioned in the text that adding sodium bentonite to water and stirring to obtain sodium bentonite suspension; dissolving cetyl trimethyl ammonium bromide in water at room temperature, then adding sorbitan oleate and stirring to obtain emulsion; then The emulsion and sodium bentonite suspension are mixed and shaken, and then centrifuged, washed, dried and pulverized to obtain modified organic bentonite, which is used as a white oil-based drilling fluid additive.

The invention patent document with the patent number of 201710265478.0 discloses a preparation method of a novel organically modified sepiolite and the application of the organically modified sepiolite. In this paper, the sepiolite is first purified, and then modified with a cationic modifier and an anionic modifier to obtain an organically modified sepiolite. The cationic modifier is not a quaternary ammonium salt of 14-18 carbon, and the anionic modifier is Sodium Lauryl Sulfate or Sodium Cetyl Sulfate. Organically modified sepiolite has good dispersibility, thixotropy and high viscosity, which can meet the requirements of oil-based drilling.

The invention patent document of application number 201610782449.7 discloses a preparation method of organic bentonite. In this paper, calcium-based bentonite is used as raw material, and sodium carbonate is added for sodiumization to obtain sodium-based bentonite slurry, then polyacrylamide is added for reaction, pressure filtration, and then dibutyl phthalate (emulsifier) is added for modification. It is then transferred into a kneader and kneaded with dimethyloctadecylbenzyl ammonium chloride to obtain organic bentonite.

The invention patent document with the patent number of 201110235817.3 discloses a preparation method of high-performance organic bentonite. In this paper, sodium bentonite is used as raw material, and two types of modifiers are used for modification, one is quaternary ammonium salt (hexadecyl trimethyl ammonium chloride, hexadecyl pyridine, octadecyl trimethyl chloride). One of ammonium chloride and octadecyldimethylbenzyl ammonium chloride), the other is an intercalating agent (one of caprolactam, fatty alcohol polyoxyethylene ether AEO, octadecyl polyoxyethylene ether). kind). The prepared organobentonite is beneficial to improve the rheology and rock-carrying ability of drilling fluid.

To sum up, the clay minerals mainly targeted for the modification of organoclay are bentonite, sepiolite, and fibrous clay, and the modifiers are mainly quaternary ammonium salts with different carbon chain lengths. In order to improve the suspension stability of organoclay in oily systems, nonionic or anionic surfactants will be added on the basis of quaternary ammonium salt modification to achieve synergistic effects.

The application performance of organoclay in paints, inks, oil field drilling and other fields is mainly reflected in its thickening, suspension and thixotropic properties in the corresponding fields. Organoclays prepared using a single type of clay often exhibit insufficient thickening or suspending properties during use. The present invention aims to select a suitable clay for compounding, and prepare an organoclay product with high thickening performance through the optimization of modified auxiliary agents.

SUMMARY OF THE INVENTION

The present invention aims to solve the above-mentioned problems, thereby providing an organoclay composition. The organoclay compositions of the present invention have the advantage of high rheology.

The technical scheme that the present invention solves the above-mentioned problem is as follows:

An organoclay composition mainly consists of montmorillonite, sepiolite and long-chain alkyl quaternary ammonium salt; the organoclay composition comprises the following components by mass:

Montmorillonite: 50～70,

Sepiolite: 10 to 30,

Long-chain alkyl quaternary ammonium salt: 30～50,

Auxiliary: 1.1～15.

As a preference of the above technical solution, the montmorillonite is selected from one or both of sodium-based montmorillonite and artificial sodium montmorillonite; the auxiliary agent includes auxiliary agent A and auxiliary agent B, and auxiliary agent A is selected from One or more of low molecular weight polyacrylate (molecular weight 500-5000), low molecular weight polyacrylate (molecular weight 500-5000) and hydroxycarboxylate; the addition amount of auxiliary A is 0.1 of the mass of clay powder ~5%; the auxiliary agent B is selected from one or more of oleic acid amide, fatty acid amide, lactic acid fatty acid amide, stearic acid amide, oleic acid ester, linoleic acid ester, and ricinoleic acid ester; auxiliary agent The dosage of B is 1-10% of the mass of the clay powder.

Another object of the present invention is to provide a method for preparing the above clay composition.

A preparation method of an organoclay composition, comprising the following steps:

1) Disperse the clay powder in water, stir, and purify by centrifugation to form a suspension with a concentration of 2-6wt%;

2) Add a pH adjuster to the suspension, adjust the pH of the slurry to be between 5 and 9, and stir at a constant temperature of 40 to 80°C for 0.5 to 1 hour;

3) Add Auxiliary A, stir at a constant temperature of 40～80℃ for 0.5～1 hour;

4) Add long-chain alkyl quaternary ammonium salt for modification, and stir at a constant temperature of 40-80°C for 1-10 hours;

5) Add Auxiliary B, stir at a constant temperature of 40～80℃ for 0.5～1 hour;

6) Add pH regulator, adjust the pH of the slurry between 8 and 10, and stir at a constant temperature of 40 to 80 °C for 0.5 to 1 hour;

7) Filter, wash, dry and pulverize to obtain the product;

The auxiliary agent A is selected from one or more of low molecular weight polyacrylate (molecular weight 500-5000), low molecular weight polyacrylate (molecular weight 500-5000) and hydroxycarboxylate; the addition amount of auxiliary agent A is 0.1 to 5% of the mass of clay powder;

Described auxiliary agent B is selected from one or more in oleic acid amide, fatty acid amide, lactic acid fatty acid amide, stearic acid amide, oleic acid ester, linoleic acid ester, ricinoleic acid ester; The consumption of auxiliary agent B is 1-10% of the mass of clay powder.

Preferably, the additive amount of the auxiliary agent A is 0.2-3% of the mass of the clay powder.

Preferably, the addition amount of the auxiliary agent B is preferably 2-7% of the mass of the clay powder.

Preferably, the clay powder in step 1) includes montmorillonite and sepiolite, and the montmorillonite is selected from one or both of sodium-based montmorillonite and artificial sodium-sodium montmorillonite.

Preferably, the pH regulators described in steps 2) and 6) are selected from one or more of sulfuric acid, hydrochloric acid, triethanolamine, and sodium hydroxide.

Preferably, the structural formula of the long-chain alkyl quaternary ammonium salt in step 4) is:

wherein M is chloride or bromide;

The structural formula of R1 is CH ₃ (CH ₂ ) _n -, n=11～21;

The structural formula of R2 is CH ₃ - or CH ₃ (CH ₂ ) _n -, n=11～21;

Wherein R3, R4 structural formula is CH ₃ -.

Preferably, the long-chain alkyl quaternary ammonium salt in step 4) consists of two components: quaternary ammonium salt A and quaternary ammonium salt B, and R2 of quaternary ammonium salt A is CH ₃ (CH ₂ ) _n -, n=11～ 21; R2 of the quaternary ammonium salt B is CH ₃ -; wherein the dosage of the quaternary ammonium salt A is 15-50% of the mass of the clay, and the dosage of the quaternary ammonium salt B is 10-40% of the mass of the clay.

The purpose of step 4) is to modify the viscosity material by intercalation, wherein the quaternary ammonium salt A has obvious effect of improving the interlayer spacing of the montmorillonite, and the quaternary ammonium salt B has the effect of supplementing the intercalation of the clay. The dispersing, suspending and thickening properties of the samples prepared by the simultaneous use of the two quaternary ammonium salts were all good.

The purpose of step 5) of the present invention is to intercalate non-ionic organic molecules into the clay layers through the principle of adsorption, so as to achieve an emulsification and dispersion effect, and this step has a significant role in promoting the application of the product in a low-polarity system. .

Preferably, the moisture content of the product obtained after drying and pulverizing in step 7) is less than or equal to 5%, and the dry powder fineness is less than or equal to 200 mesh.

To sum up, the present invention has the following beneficial effects:

The organoclay composition of the present invention is mainly composed of montmorillonite, sepiolite and long-chain alkyl quaternary ammonium salt, and also contains a small amount of organic auxiliary agent; and is prepared by a specific process. The organoclay composition modified by the process of the present invention not only has good dispersibility, suspension and thickening properties, but also has the advantages of high rheology, which can effectively promote the application in low-polarity systems.

Detailed ways

In order to deepen the understanding of the present invention, the present invention will be further described in detail below with reference to the embodiments. The embodiments are only used to explain the present invention, and do not constitute a limitation on the protection scope of the present invention.

Implementation Example 1:

Weigh 1000 g of sodium-based montmorillonite powder, add 20 kg of water, fully stir and disperse, and purify by centrifugation to obtain a purified sodium-based montmorillonite suspension. The solid content of the test suspension is 30 g/L. Take 5L of purified sodium-based montmorillonite suspension in the reactor, heat up to 70°C, and keep stirring at constant temperature; add dilute sulfuric acid, adjust the pH of the slurry to 7-8, stir for 30 minutes, add 3g of low molecular weight sodium polyacrylate (2% soil ), stirred at a constant temperature of 70 °C for 1 h; added 70 g of dioctadecyldimethylammonium chloride (47% soil), 40 g of octadecyltrimethylammonium chloride (27% soil), and stirred at a constant temperature of 70 °C for 2 hours; Add 7.5 g of oleic acid amide (5% soil), stir at 70 °C for 1 h; add sodium hydroxide solution, adjust the pH of the slurry to 8-9, stir at 70 °C for 30 minutes, cool to room temperature, filter, wash, dry, and pulverize to obtain the sample , the label is FH-1.

Implementation Example 2:

Weigh 500 g of sepiolite powder, add 10 kg of water, fully stir and disperse, and purify by centrifugation to obtain a purified sepiolite suspension. The solid content of the test suspension was 20 g/L. Take 5L of purified sepiolite suspension in the reactor, heat up to 70°C, and keep stirring at constant temperature; add dilute sulfuric acid, adjust the pH of the slurry to 7-8, stir for 30 minutes, add 2g of low molecular weight sodium polyacrylate, and stir at 70°C for 1 hour ; Add 47 g of dioctadecyl dimethyl ammonium chloride and 27 g of octadecyl trimethyl ammonium chloride, stir at a constant temperature of 70 °C for 2 hours; add 5 g of oleic acid amide, stir at a constant temperature of 70 °C for 1 hour; add sodium hydroxide solution , adjust the pH of the slurry to 8-9, stir at a constant temperature of 70°C for 30 minutes, cool to room temperature, filter, wash, dry, and pulverize to obtain a sample, labeled as FH-2.

Implementation Example 3:

Weigh 4L of the purified sodium-based montmorillonite suspension in Example 1, weigh 1L of the purified sepiolite suspension in Example 2, stir and mix thoroughly to obtain a mixed clay suspension, and the solid content of the test suspension is 28g/L . The mixed clay suspension was heated to 70°C and kept stirring at constant temperature; dilute sulfuric acid was added to adjust the pH of the slurry to 7-8, stirred for 30 minutes, 2.8 g of low molecular weight sodium polyacrylate was added, and stirred at a constant temperature of 70°C for 1 h; dioctadecyl was added 66 g of dimethyl ammonium chloride, 37.8 g of octadecyl trimethyl ammonium chloride, stirred at a constant temperature of 70 °C for 2 hours; added 7 g of oleic acid amide, stirred at a constant temperature of 70 °C for 1 hour; added sodium hydroxide solution to adjust the pH of the slurry to 8-9 , 70 ℃ constant temperature stirring for 30 minutes, cooled to room temperature, filtered, washed, dried, pulverized to obtain a sample, labeled as FH-3.

Implementation Example 4:

Weigh 3L of the purified sodium-based montmorillonite suspension in Example 1, weigh 2L of the purified sepiolite suspension in Example 2, fully stir and mix to obtain a mixed clay suspension, and the solid content of the test suspension is 26g/L . The mixed clay suspension was heated to 70°C and kept stirring at constant temperature; dilute sulfuric acid was added to adjust the pH of the slurry to 7-8, stirred for 30 minutes, 2.6 g of low molecular weight sodium polyacrylate was added, and stirred at a constant temperature of 70°C for 1 h; dioctadecyl was added 61 g of dimethyl ammonium chloride, 35 g of octadecyl trimethyl ammonium chloride, stirring at 70 °C for 2 hours; adding 6.5 g of oleic acid amide, stirring at constant temperature at 70 °C for 1 hour; adding sodium hydroxide solution to adjust the pH of the slurry to 8-9 , 70 ℃ constant temperature stirring for 30 minutes, cooled to room temperature, filtered, washed, dried, pulverized to obtain a sample, labeled as FH-4.

Implementation Example 5:

Weigh 2.5L of the purified sodium-based montmorillonite suspension in Example 1, weigh 2.5L of the purified sepiolite suspension in Example 2, fully stir and mix to obtain a mixed clay suspension, and the solid content of the test suspension is 25g /L. The mixed clay suspension was heated to 70°C and kept stirring at constant temperature; dilute sulfuric acid was added to adjust the pH of the slurry to 7-8, stirring for 30 minutes, 2.5 g of low molecular weight sodium polyacrylate was added, and the constant temperature stirring was carried out at 70°C for 1 h; dioctadecyl was added 59 g of dimethyl ammonium chloride, 34 g of octadecyl trimethyl ammonium chloride, stirred at 70 °C for 2 hours; added 6.2 g of oleic acid amide, stirred at constant temperature at 70 °C for 1 hour; added sodium hydroxide solution to adjust the pH of the slurry to 8-9 , 70 ℃ constant temperature stirring for 30 minutes, cooled to room temperature, filtered, washed, dried, pulverized to obtain a sample, labeled as FH-5.

Implementation Example 6:

Weigh 4L of the purified sodium-based montmorillonite suspension in Example 1, weigh 1L of the purified sepiolite suspension in Example 2, stir and mix thoroughly to obtain a mixed clay suspension, and the solid content of the test suspension is 28g/L . The mixed clay suspension was heated to 70°C and kept stirring at constant temperature; dilute sulfuric acid was added to adjust the pH of the slurry to 7-8, stirred for 30 minutes, 2.8 g of low molecular weight sodium polyacrylate was added, and stirred at a constant temperature of 70°C for 1 h; dioctadecyl was added 56 g of dimethyl ammonium chloride (40% soil), 28 g of octadecyltrimethyl ammonium chloride (20% soil), stirred at a constant temperature of 70 °C for 2 hours; added 7g of oleic acid amide, stirred at a constant temperature of 70 °C for 1 hour; added hydrogen Sodium oxide solution, adjust the pH of the slurry to 8-9, stir at a constant temperature of 70°C for 30 minutes, cool to room temperature, filter, wash, dry, and pulverize to obtain a sample, designated as FH-6.

Implementation Example 7:

Weigh 4L of the purified sodium-based montmorillonite suspension in Example 1, weigh 1L of the purified sepiolite suspension in Example 2, stir and mix thoroughly to obtain a mixed clay suspension, and the solid content of the test suspension is 28g/L . The mixed clay suspension was heated to 70°C and kept stirring at constant temperature; dilute sulfuric acid was added to adjust the pH of the slurry to 7-8, stirred for 30 minutes, 2.8 g of low molecular weight sodium polyacrylate was added, and stirred at a constant temperature of 70°C for 1 h; dioctadecyl was added 70 g of dimethyl ammonium chloride (50% soil), 42 g of octadecyltrimethyl ammonium chloride (30% soil), stirred at a constant temperature of 70 °C for 2 hours; added 7g of oleic acid amide, stirred at a constant temperature of 70 °C for 1 hour; added hydrogen Sodium oxide solution, adjust the pH of the slurry to 8-9, stir at a constant temperature of 70°C for 30 minutes, cool to room temperature, filter, wash, dry, and pulverize to obtain a sample, designated as FH-7.

Implementation Example 8:

Weigh 4L of the purified sodium-based montmorillonite suspension in Example 1, weigh 1L of the purified sepiolite suspension in Example 2, stir and mix thoroughly to obtain a mixed clay suspension, and the solid content of the test suspension is 28g/L . The mixed clay suspension was heated to 70°C and kept stirring at constant temperature; dilute sulfuric acid was added to adjust the pH of the slurry to 7-8, stirring for 30 minutes, and constant temperature stirring at 70°C for 1 h; adding 70 g of dioctadecyldimethylammonium chloride (50 % soil), octadecyltrimethylammonium chloride 42g (30% soil), stirred at 70°C for 2h; add 7g oleic acid amide, stir at 70°C for 1h; add sodium hydroxide solution, adjust the pH of the slurry to 8-9 , 70 ℃ constant temperature stirring for 30 minutes, cooled to room temperature, filtered, washed, dried, pulverized to obtain a sample, labeled as FH-8.

Implementation Example 9:

Weigh 4L of the purified sodium-based montmorillonite suspension in Example 1, weigh 1L of the purified sepiolite suspension in Example 2, stir and mix thoroughly to obtain a mixed clay suspension, and the solid content of the test suspension is 28g/L . The mixed clay suspension was heated to 70°C and kept stirring at constant temperature; dilute sulfuric acid was added to adjust the pH of the slurry to 7-8, stirred for 30 minutes, 2.8 g of low molecular weight sodium polyacrylate was added, and stirred at a constant temperature of 70°C for 1 h; dioctadecyl was added 70 g of dimethyl ammonium chloride (50% soil), 42 g of octadecyltrimethyl ammonium chloride (30% soil), stirred at a constant temperature of 70 °C for 2 hours; add sodium hydroxide solution, adjust the pH of the slurry to 8-9, 70 °C Stir at a constant temperature for 30 minutes, cool to room temperature, filter, wash, dry, and pulverize to obtain a sample, designated as FH-9.

The rheological viscosity was measured by dispersing the sample in white oil in the implementation case. The test method was as follows: Weigh 10g of the organoclay sample, disperse it in 90g of white oil, stir and disperse, the speed is 2000rpm, the stirring time is 10min, and the stirring process is maintained. The temperature was kept constant at about 30°C, and the prepared gel was placed in a rotational viscosity agent to test the viscosity. The test results are shown in Table 1.

It can be seen from the table that the samples prepared according to the patented scheme of the present invention have higher thickening performance in the solvent.

Table 1: Sample Rheological Viscosity Test Data

Claims (10)

1. An organoclay composition characterized by: mainly comprises montmorillonite, sepiolite and long-chain alkyl quaternary ammonium salt; the organic clay composition comprises the following components in parts by mass:

montmorillonite: 50 to 70 of the total amount of the organic solvent,

sepiolite: 10 to 30 parts of a solvent, and a solvent,

long-chain alkyl quaternary ammonium salt: 30 to 50 of the total amount of the organic compounds,

auxiliary agent: 1.1 to 15.

2. An organoclay composition according to claim 1, characterised in that: the montmorillonite is selected from one or two of sodium montmorillonite and artificial sodium montmorillonite; the auxiliary agent comprises an auxiliary agent A and an auxiliary agent B, wherein the auxiliary agent A is selected from one or more of low molecular weight polyacrylate, low molecular weight polyacrylate and hydroxyl carboxylate; the addition amount of the additive A is 0.1-5% of the mass of the clay powder; the auxiliary agent B is selected from one or more of oleamide, fatty acid amide, lactic acid fatty acid amide, stearic acid amide, oleate, linoleate and ricinoleate; the dosage of the auxiliary agent B is 1-10% of the mass of the clay powder.

3. A method of preparing an organoclay composition comprising the steps of:

1) dispersing clay powder in water, stirring, and carrying out centrifugal purification to form a suspension with the concentration of 2-6 wt%;

2) adding a pH regulator into the suspension, adjusting the pH of the slurry to be between 5 and 9, and stirring at the constant temperature of 40 to 80 ℃ for 0.5 to 1 hour;

3) adding the auxiliary agent A, and stirring at the constant temperature of 40-80 ℃ for 0.5-1 hour;

4) adding long-chain alkyl quaternary ammonium salt for modification, and stirring at constant temperature of 40-80 ℃ for 1-10 hours;

5) adding the auxiliary agent B, and stirring at the constant temperature of 40-80 ℃ for 0.5-1 hour;

6) adding a pH regulator, adjusting the pH of the slurry to be between 8 and 10, and stirring at the constant temperature of between 40 and 80 ℃ for 0.5 to 1 hour;

7) filtering, washing, drying and crushing to obtain a product;

the auxiliary agent A is selected from one or more of low molecular weight polyacrylate, low molecular weight polyacrylate and hydroxyl carboxylate; the addition amount of the additive A is 0.1-5% of the mass of the clay powder;

the auxiliary agent B is selected from one or more of oleamide, fatty acid amide, lactic acid fatty acid amide, stearic acid amide, oleate, linoleate and ricinoleate; the dosage of the auxiliary agent B is 1-10% of the mass of the clay powder.

4. The process of claim 3 for preparing an organoclay composition, wherein: the addition amount of the additive A is 0.2-3% of the mass of the clay powder.

5. The process of claim 3 for preparing an organoclay composition, wherein: the addition amount of the auxiliary agent B is preferably 2-7% of the mass of the clay powder.

6. The process of claim 3 for preparing an organoclay composition, wherein: the clay powder material in the step 1) comprises montmorillonite and sepiolite, wherein the montmorillonite is one or two of sodium-based montmorillonite and artificial sodium montmorillonite.

7. A process for preparing an organoclay composition according to claim 3, wherein: the pH regulator in the steps 2) and 6) is one or more selected from sulfuric acid, hydrochloric acid, triethanolamine and sodium hydroxide.

8. A process for preparing an organoclay composition according to claim 3, wherein: the structural formula of the long-chain alkyl quaternary ammonium salt in the step 4) is as follows:

wherein M is chloride or bromide;

wherein R1 is CH₃（CH₂）_n-,n=11～21；

Wherein R2 is CH₃-or CH₃（CH₂）_n-,n=11～21；

Wherein R3 and R4 are CH₃-。

9. A process for preparing an organoclay composition according to claim 3, wherein: the long-chain alkyl quaternary ammonium salt in the step 4) consists of two components, namely quaternary ammonium salt A and quaternary ammonium salt B, wherein R2 of the quaternary ammonium salt A is CH₃（CH₂）_n-n =11 to 21; r2 of quaternary ammonium salt B is CH₃-; wherein the dosage of the quaternary ammonium salt A is 15-50% of the mass of the clay, and the dosage of the quaternary ammonium salt B is 10-40% of the mass of the clay.

10. A process for preparing an organoclay composition according to claim 3, wherein: and 7) drying and crushing to obtain a product, wherein the water content of the product is less than or equal to 5%, and the fineness of the dry powder is less than or equal to 200 meshes.