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Introduction and application of silica gel raw materials

Introduction and application of silica gel raw materials

Silica (silicon dioxide), is a highly reactive adsorption material, amorphous material, the chemical molecular formula for the msio2 nH2O, obtained by silica gel dry dehydration, main component can not be said to be SiO2. Insoluble in water and any solvent, non-toxic and tasteless, stable chemical properties, in addition to the strong alkali, hydrofluoric acid is not with any substance react. Silica gel according to the size of the aperture is divided into: macroporous silica gel, macro pore silica gel, type B silica gel, gel pore. Various types of silicone due to their different manufacturing methods formed with different pore structure. Silicone instead of silicon rubber, silicone rubber is a kind of synthetic rubber.

Silicone production process

Although most of the production of silica gel after washing and drying the common, but specific to a certain type of plastic, there are different processes, phase

Mutual difference of personality.

Folding gel granulation process

Gel granulation is one of the key steps in the production of silicone, it refers to a certain concentration of dilute sulfuric acid and dilute sodium silicate solution under conditions to form filled sol-gel solution to form gel particles of a certain concentration. Gel particle shape and size of the mountain is completely user needs the ability to determine the production process, Off "almost a gel method, before use of air granulation, when the fine particle size requirements, taking into account the degree of air granulation, for the most part a reaction tank granulated gel, for example, silica powder production. The proportion of acid used in the gel, the concentration, temperature and time the gel granulation process specific parameters of the gel granulation process.

The acidic gel (pH Proportion) when a gel particle r (relatively small primary particles to small, easy to form silica pore structure when aggregated; alkaline gelation, the gel tablets r a large, easy to gather formation of coarse porous silica, which is the production of crude rubber into the hole preferably an alkaline gel pore plastic production is preferable acidic gelation truth.

Acid concentration should be moderate. Acid concentration is too high, a gel particle r large, become coarse pore silica gel when aggregated, Ifn gel solution primary particle concentration is also large, that tightness gel network structure increases aggregate Shiyou Yi pores become, one has a tendency to cancel each other out. Furthermore, the acid concentration is too high, the viscosity of the gel solution is increased to granulation bring some degree of difficulty. In addition, the size of the acid concentration is also subject to restrictions gel particle size, structure and production design capacity and the like.

PH temperature is too high. Acid-base reaction speed is too fast. Wooden body acid-base reaction is exothermic reaction exothermic once again gather grain r. Therefore, such a large grain r had any. "Granulated deceleration slow bound to go beyond the scope of the granulation process requirements disadvantage;. pH temperature is too low to reduce the primary particle r easy to form pores but the mountain "several gel solution temperature is too low, increase the viscosity of the granulated also unfavorable... . Therefore, the temperature should be moderate pH.

Gel time is the gel granulation granulation process is another critical process parameters. It refers to a mixed reaction from the beginning to the particle size of the gel-forming acid until the elapsed time, including time and granulated gel time. Granulated gel short time may make the gel solution does not react sufficiently or uniformly enough. So that the concentration of a particle r unevenly distributed. Topical gel formation or closely packed locally. This creates a bubble granulation process glue. shredded rubber or rubber ball strong enough and so on. This was also caused by the internal structure of disordered particles rubber ball. Macropore distribution is a major cause. Therefore, in the production practice. To several air granulation. In the process of the allowable range. Large particles of plastic. The time to as long as possible. Small particles of plastic. Shorter time may be appropriate. In the reactor tank gel granulating ultrafine silica balls will have a longer time to be added and stirred.

Wash plastic folding process

Wash silicone rubber is essential in the production process. NazSO to the particulate gel is washed off}, 7 {respective yin and yang from r (mainly H +, N expansion, SO was a, Si0 wear iY} r, etc.) to control the process within the required range. At the same time. It is also an adjustment of the internal structure of the particles (ie aging) process.

Exchange adsorption (ie, Na and H exchange ten ten) phenomenon is one of the washing process rubber wood properties. Acid soak process is the main process .1 exchange adsorption} ´a´ H + exchange and multi completed in this process. Switching the washing process is far from being just stop getting smaller and smaller exchange capacity. Acid concentration bubble, Water medium temperature water wash glue process the main process parameters affecting the exchange rate and quantity.

Silica pore characteristics of the finished part of a big mountain of plastic washing aging process decision, and the aging process depends wash gel medium temperature. Pad cleaning medium, the temperature of the primary particles is controlled growth "of the main factors, i.e., by adjusting the increase in primary particle" adjustment to achieve the purpose of the pore structure.

Washing gel pores required to suppress aging, therefore, the gel is formed after the granulation necessary and after a short aging into the acid soak, wash gum throughout the media must be acidic, acidic medium because it can prevent primary particles´ grow up ", a large amount of acid that is determined to inhibit aging in size. At the same time, wash the glue temperature should be lower, because the aging process is to absorb energy, low temperature, low energy supply, aging naturally small. That pores washing gel by inhibiting ´grown primary particles "to achieve the purpose of adjustment of the pore structure. Special requirements for thorough pore structure (ie, the distribution of small holes) _ Head bulk density and pore plastic production requires a certain range, for example, pressure swing adsorption pore COz special rubber production. Washing the acid content, temperatures are strict requirements to make plastic wash. Low temperature washing gel pores, switching speed is slow, so the washing time to be longer, but not too big, too long, especially near the end from the time, but accelerated aging.

Rough hole rubber production is required to promote aging. Follow alkaline medium, high temperature hot water to promote the principles of aging, taken before the acid was added hot water soak, head _ managed to significantly alkaline, increase the temperature of the washing process, at the end, adding a certain concentration of ammonia to increase 0 H- ions concentration and other measures to promote primary particles "grow up" to expand the aperture, to achieve the purpose of aging is easy to see, in the whole washed off, the aging upward trend. water temperature is high, not only inside the particles of the primary particles grow up, especially between the particles between powder particles also "grow up" trend, which is water temperature is high, powder gathered at the cake easily, gum balls and sticky powder form another main reason.

For coarse aperture hole that is interposed between the thickness of plastic such as T3 type plastic production, moderate aging can sometimes buffer during drying liquid tension tables, washing tables-end processing. Temperature is too high, too long, there is a treatment liquid rubber ball will change, so the application of the treatment liquid to be limited by the drying process conditions.

Folding drying process

Drying under a liquid surface tension, evaporation of water particles so that rubber ball volume contraction, the primary particles again together "grow up", to a depth of aging purposes. In order to suppress the pore plastic aging, often by controlling the intake when dry rubber ball in the acid content reaches day. In practice, the thickness of the multi-hole glue dried under normal temperature conditions. The higher the drying temperature, the greater the polymer primary particles 7 {r speed, the larger the aperture. Roasting reaming is the truth. To produce hydrocarbons shrink little hole, not even shrinkage of the silicone is often used to reduce tension in the liquid form and methods to achieve the day.

Process characteristics of the finished silicone rubber quality parameters and indicators of process characteristics determines the quality of the relationship between silicone rubber parameter index finished, turn indicators finished rubber quality parameters in turn requires a certain process control characteristics. Now on the bulk density of the finished plastic Case analysis of the relationship between a person. The bulk density is an important quality parameter of the silica gel product analysis, Ifn intuitively simple physical parameters of the reaction of the internal pore structure of silica gel particles. Silica gel is a porous solid particles, formed its apparent volume V u} actual mountain two parts, the first part of the silica particles inside the actual pore volume sheet to V a} representation. The first part is when the pores between the particles accumulate in V},} representation. The second part is a silica gel kidney frame has the size to Vi. FIG. Such V u} - = V},} + V a} + V t, =, set n, the quality of the silica, to obtain Pug- = m / V}, ´} + V}} + V i´, = (do not have "several silica density Porgy = mlVa} + Vi ´, =).

Under the same conditions, a certain pore volume of the silica, corresponds to a certain bulk density, A, T3, C two types of glue pore size, pore volume gradually increases, V u} is successively reduced, which is the difference between the bulk density becomes a, T3, C is based on two types of glue, even in the same type of film, the pore structure of the bulk density of the size of a rough judgment silica particles inside.

Under normal circumstances, when the acidic gel, a grain r small, small aperture gathered into gel particles, under the same conditions, the aperture form the finished silicone also small, a volume of silica gel Va: small, large natural bulk density, alkaline gelation, bulk density is small. Air granulation, if the formation of bubble gum, loose structure, or due to other causes a gel particle concentration reduction r etc make the finished rubber V a} increases,

From Ifn make Par reduced.

Conditions on the finished rubber glue wash bulk density, for example, the production of A type of plastic, the plastic medium has an acidic wash, low temperature, a grain r ´grown´ amplitude is small, that is a small degree of aging, finished small rubber V a} , Pir naturally large, different acid content, the degree of inhibition of aging is also different, Pir is different. this is the wash gel process through a phased sampling method to analyze a bulk density of the main basis for the various stages of aging. rubber pair of holes production took acid before the bubble with an alkaline hot water aging period, hot water washing, and sometimes from plastic and other measures to end l treatment with ammonia, so big because Ifn aging, pore volume of finished gum increases, Pir is small .

Folding edit this paragraph storage method

Stored in a sealed container, and placed in a cool, dry place, away from humidity and water.

Folding Edit this paragraph Synthesis

1. Selection of quartz sand and sodium hydroxide reagent and dried after washing with water after heating eutectic acidified with hydrochloric acid, in solution polymerization formed polymer gel, washed with water to remove chloride ions, is granulated after drying Silica gel. For dehydration or purification of finished silicone has a different shape: irregular shape and ball shape. For gas chromatography stationary phase should be irregularly shaped silica mesh with a certain range; for liquid chromatography stationary phases should have been pretreated, and having a ball-shaped mesh silica certain range.

Bonding method

First clean the surface to be bonded, glue (mainly rely on air acts to trace moisture curing, not too thick layer, layer thickness ≤5mm, generally one to two millimeters thick), pressure, less than 12 hours, using the best after 24 hours.

Three: performance parameters

Temperature range (℃): - 50 ~ + 230 Relative density: (g / cm3) 1.05 ~ 1.15

Fluid viscosity: 150000 ± 450 Tensile strength (kg / cm2): ≥25 ± 5

Shear strength (Mpa): ≥21 shock resistance "(times) 300 / min


100ML / branch (aluminum), 300ML / branch (plastic tube)

[Shelf life]

Store in a cool dry place at room temperature maintained for a period of 8 months

Mainly used for silicone and plastic (viscosity silicone seals, silicone wristbands, silicone bra, silicone case, silicone tube, silicone medical accessories, silicone Pipes, silicone component materials, glass, aluminum, foam material, nylon cloth, textiles adhesive resin glue, leather, sponge, between.

H-1508T glue

Silicone Silicone adhesive for glue is a silicone rubber adhesive for silicone and silicone, silica and the plastic-like adhesive, it is bonded to rely on contact with water molecules or water molecules in the air of the cured sealing surface.

Edit this paragraph The main purpose of folding

1. In the livestock sector in the multi-purpose silicone 300 Preparation of choline chloride powder, the particles increase vitamin A, loose degree D, E, B2 of. 2. used as gas chromatography and liquid chromatography stationary phase. Also for gas and liquid dehydration and purification.

Folding Edit this paragraph safety information

Folding term risk

R20: Harmful if inhaled ‖R37;

Folding Security Terminology

S22: Do not breathe dust ‖S45;

Folding Edit this paragraph numbering system

CAS: 112926-00-8

Number MDL: MFCD00011232

EINECS Number: 231-545-4

RTECS Number: VV7565000

PubChem ID: 24854187

Folding edit this paragraph Computational Chemistry Data

1, hydrophobic parameter calculation reference value (XlogP):

2, the number of hydrogen bonds for the body:

3, the number of hydrogen bond acceptors:

4, rotatable bond number:

5, topological molecular polar surface area (TPSA):

6, the number of heavy atoms:

7, the surface charge:

8, Complexity:

9, the number of atomic isotopes: 0

10, to determine the number of atoms stereocenter: 0

11, the number of uncertain atoms stereocenter: 0

12, to determine the chemical bond stereocenter number: 0

13, the number of uncertain chemical bond stereocenter: 0

14, the number of covalent bond units: 1

Edit this paragraph silicone adhesive fold of

k-780 silicone adhesive suitable for plastic, metal.

k-780 silicone adhesive applied to silica gel, glass, fabrics.

k-680 applies to 50 degrees below silicone adhesive.

k-630 applies to more than 50 degrees silicone adhesive, to be equipped with treatment agent.


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