CN101618876A - Method for preparing precipitated white carbon black with controllable specific surface area - Google Patents

Abstract

The invention relates to a preparation method of a chemical raw material, namely a method for preparing precipitated white carbon black with controllable specific surface area. The raw materials comprise water glass with modulus of 3.3-3.5 and water solution proportion of 1.085+/-0.001 and 15 percent of sulphuric acid. The method comprises the following steps: reaction: when the quantity of bottom material and the water glass is 30-80 percent of the total inventory rating, stirring, and rising the temperature to 84+/-1 DEG C, beginning to add the 15 percent of sulphuric acid for reaction, then adding the water glass and the sulphuric acid and keeping the pH value constant when the pH value of a suspending liquid reaches 9-10, finishing the addition of the left 70-20 percent of water glass within 55min, continuously adding the sulphuric acid to enable the water glass to completely react and adjusting the pH value to be 2-3; washing with water and drying: filtering the suspending liquid by a filter and drying by a spray dryer. The preparation method can be used for preparing the white carbon black with the specific surface area of 50-250 m<2>/g, which is particularly suitable for being used as rubber reinforcing filler.

Description

Method for preparing precipitated white carbon black with controllable specific surface area

Technical field

The present invention relates to a kind of preparation method of industrial chemicals, i.e. method for preparing precipitated white carbon black with controllable specific surface area.

Background technology

In the prior art, specific surface area is important technology index of white carbon black, and it is determining the application performance of white carbon black to a great extent.Among the China chemical industry standard HG/T3061-1999 specific surface area of precipitated silica is divided into six classifications:

The precipitated hydrated silica classification

Classification	Specific surface area m 2/g	Classification	Specific surface area m 2/g
				??A	??≥191	??D	??106-135
??B	??161-190	??E	??71-105
				??C	??136-160	??F	??≤70

Annotate: precipitated hydrated silica, i.e. precipitated silica.

The production of precipitated silica at present, generally adopting water glass (water glass) and sulfuric acid is raw material, in reaction kettle for reaction, generates silicon-dioxide and byproduct sulfite, its chemical equation:

Na ₂O·MsiO ₄+H ₂SO ₄＝MsiO ₂+Na ₂SO ₄+H ₂O

In the formula: M is a modulus of water glass.

The specific surface area of white carbon black is relevant with the particle diameter of white carbon black, the relation of being inversely proportional between them, and promptly particle diameter is little, and specific surface area is big, and the relation between them can be done approximation calculation with following formula:

(nm)=6000/ (BET * proportion), primary particle footpath

BET is the specific surface area (m that white carbon black is surveyed with nitrogen adsorption method in the formula ²/ g). proportion is the true specific gravity of white carbon black, is generally 2.1-2.15.

The size of precipitated silica adopts temperature of reaction, material concentration, reaction times to control usually.In general, the temperature of reaction height, the material concentration height, long reaction time can make the particle diameter of white carbon black big, otherwise then little, changes their a certain conditions wherein, must consider the influence to other index of white carbon black.Change the restriction that processing condition all are subjected to aspects such as operational condition, product cost, equipment in addition.

Summary of the invention

The objective of the invention is to provide a kind of at above-mentioned deficiency and can satisfy the precipitated silica that is used for rubber reinforcing filler and other purposes, the specific surface area of its product can be at 50-250m ²Control arbitrarily between the/g.

Technical solution of the present invention is: the control method step of preparation precipitated silica specific surface area is as follows:

(1) raw material: water glass, modulus 3.3-3.5, aqueous solution proportion 1.085 ± 0.001; 15% sulfuric acid;

(2) reaction: bed material adds the 30-80% that the water glass amount is total charging capacity, start to stir and be warming up to 84 ± 1 ℃, begin to add 15% sulfuric acid reaction, in 40 minutes reaction times, the pH value of suspension reaches 9-10, more simultaneously and flow to and add water glass and sulfuric acid in the reactor, and keep pH value constant, remaining 70-20% water glass was added with 55 minutes, and it is intact with remainder water glass total overall reaction in the reactor to continue to add sulfuric acid with 30 minutes, and the pH value of suspension is transferred to 2-3;

(3) washing, drying:

Adopt filter that suspension is filtered, filter cake washes with water, washes sodium sulfate off, and filter cake adopts the spray-drier drying through pulp.

Advantage of the present invention is: under the constant situation of other processing condition, only change bed material and add the water glass amount, can prepare specific surface area is 50-250m ²The white carbon black of/g and control arbitrarily.This product is specially adapted to do rubber reinforcing filler, also is applicable to the multiple Application Areas such as carrier, synthetic resins, toothpaste abrasives and thickening thixotropic agent, papermaking, powder extinguishing agent, water-based separant of carrier, the feed compound of agricultural chemicals.

Below in conjunction with embodiment embodiments of the present invention are described in further detail.

Embodiment

Embodiment 1:

Use 5m ³Enamel reaction still adds modulus 3.4, the water glass 2m of proportion 1.085 ³, start 60 rev/mins agitator, warming while stirring when making the temperature of water glass solution rise to 85 ℃, keeps constant temperature, adds 15% sulfuric acid reaction with 40 minutes, and makes suspension terminal point pH value reach 9-10; Connect above-mentioned reaction, water glass and sulfuric acid also flow to dropping in the reaction, with 1m ³Water glass dripped with 55 minutes, and kept reaction process pH value 9-10 constant, and 85 ℃ of temperature are constant; Connect above-mentioned reaction, in reactor, add acid separately, will be in the reactor do not have the water glass total overall reaction of reaction intact with 30 minutes, and the pH value of suspension is transferred to 3.Suspension filters mother liquor with box filter, the washing filter cake, and the filtrate specific conductivity reaches 250-300 μ m and stops washing.Filter cake carries out pulp with hollander, carries out drying with spray-drier.Product is pulverized with ultrafine crusher.

Embodiment 2:

Bed material adds water glass 1.7m as different from Example 1 ³, water glass and sulfuric acid and drip added-time water glass dosage 1.3m ³, product is not pulverized.

Embodiment 3:

Bed material adds water glass 1.5m as different from Example 1 ³, water glass and sulfuric acid and drip added-time water glass dosage 1.5m ³, product is not pulverized.

Embodiment 4:

Bed material adds water glass 2.1m as different from Example 1 ³, water glass and sulfuric acid and drip added-time water glass dosage 0.9m ³

The white carbon black detection technique index of embodiment is listed in the table below:

Project name embodiment	BET specific surface area m 2/g	Median size μ m	Heavy real density g/cm 3	Total residue %	Weight loss on heating %	Burning decrement %	DBP absorption value ml/g	PH value	Silicon-dioxide %
										Embodiment 1	??210	??17	??0.16	??1.0	??5.1	??4.35	??2.7	??6.4	??93.5
Embodiment 2	??165	??20	??0.24	??0.9	??4.8	??4.2	??2.5	??6.5	??94.0
										Embodiment 3	??80	??20	??0.27	??0.9	??5.3	??4.4	??2.2	??6.5	??94.0
Embodiment 4	??230	??17	??0.17	??1	??5.5	??4.1	??3.0	??6.4	??93.4

Embodiment 1 belongs to than bigger serface, and the high reactivity white carbon black is mainly used in rubber and cooks strengthening agent;

Embodiment 2 belongs to medium specific surface area, and the white carbon black of middle activity is mainly used in General Purpose Rubber goods or other nonrubber goods;

Embodiment 3 belongs to low specific surface area, and the low activity white carbon black is mainly used in snappiness and extrudes rubber, high amount of filling white carbon black rubber item, heat sensitive paper;

Embodiment 4 belongs to high-specific surface area, and high DBP absorption value is applicable to the liquid thickening, carrier.

The present invention is not limited to above-mentioned 4 embodiment, adds the water glass amount as long as change bed material, all can prepare corresponding specific surface area and DBP absorption value, satisfies different application requiring.

Claims (1)

1. method for preparing precipitated white carbon black with controllable specific surface area is characterized in that step is as follows:

(1) raw material: water glass, modulus 3.3-3.5, aqueous solution proportion 1.085 ± 0.001; 15% sulfuric acid;

(2) reaction: bed material adds the 30-80% that the water glass amount is total charging capacity, start to stir and be warming up to 84 ± 1 ℃, begin to add 15% sulfuric acid reaction, in 40 minutes reaction times, the pH value of suspension reaches 9-10, more simultaneously and flow to and add water glass and sulfuric acid in the reactor, and keep pH value constant, remaining 70-20% water glass was added with 55 minutes, and it is intact with remainder water glass total overall reaction in the reactor to continue to add sulfuric acid with 30 minutes, and the pH value of suspension is transferred to 2-3;

(3) washing, drying:

Adopt filter that suspension is filtered, filter cake washes with water, washes sodium sulfate off, and filter cake adopts the spray-drier drying through pulp.