CN102134331B

CN102134331B - Recycling method of waste silicone rubber

Info

Publication number: CN102134331B
Application number: CN2011100236612A
Authority: CN
Inventors: 许华建; 吴伟; 章丰丰; 齐洪侠; 冯乙巳
Original assignee: Hefei University of Technology
Current assignee: Hefei University of Technology
Priority date: 2011-01-21
Filing date: 2011-01-21
Publication date: 2012-08-22
Anticipated expiration: 2031-01-21
Also published as: CN102134331A

Abstract

The invention provides a recycling method of waste silicone rubber, which comprises the following processes of: preparation of solid acid, catalytic cracking of the waste silicone rubber, post-treatment and separation of respective units, wherein the catalytic cracking comprises the following steps of: cracking at 120-150 DEG C for 3-4 hours after crushed waste silicone rubber and a 0.5-5% solid acid catalyst are uniformly mixed, distilling and separating after the cracking reaction, and collecting a crude product DMC (DiMethyl Carbonate); and the post-treatment comprises the following steps of: adding an inorganic acid catalyst into the crude product DMC to react at 100-140 DEG C for 2-3 hours, adding an alkali solution to terminate the reaction, and finally, rectifying and separating to obtain high-quality DMC. When the method is adopted, the recycling rate can stably reach over 50% in terms of silicon rubber, wherein the content of MM can be controlled below 0.01%; the recycling method can be directly applied to the polymerization of the silicon rubber without influencing the quality of the silicon rubber.

Description

A kind of recoverying and utilizing method of waste silicone rubber

One, technical field

The present invention relates to three wastes treatment process, particularly the recoverying and utilizing method of solid waste, the specifically recoverying and utilizing method of waste silicone rubber.

Two, background technology

Zylox has nonpoisonous and tasteless, many particular performances such as high-low temperature resistant, electrical apparatus insulation and physiology inertia.For other organic polymer materials can not compare and substitute, thereby be used widely, and become the important and requisite novel high polymer material of national economy at aspects such as space flight, chemical industry, agricultural and health cares.Along with the fast development of Zylox industry and the quick growth of consumption; The Zylox waste product and the scrap stock that form in the useless time raw-silastic continuously that in building-up process, produces, the sulfidization molding processing, and the waste silicone rubber goods that in application process, form increase sharply.Consider global environment problem and power saving, the low carbon-based industry of development realizes that it is a problem that can not be ignored that waste recovery is utilized again.Therefore, handle various waste silicone rubbers rationally, effectively, to reducing production costs, make full use of resource, protect environment and guaranteeing that the continuing of Zylox production and application, fast development are all significant.

In polyreaction, be thermodynamic equilibrium between DMC (n >=3, when n=2, promptly two trimethylammonium silica condense together, code name MM for ring dimethyl siloxane, Dn) and the superpolymer.If waste silicone rubber neutral line dimethyl siloxane (PDMS) is cracked into DMC in the presence of acid and basic catalyst, and constantly from reaction system, removes, the Zylox superpolymer is converted into DMC.According to this principle, invented the multiple method that from waste silicone rubber, reclaims DMC, at present, main still acid-catalyzed cleavage method and the base catalysis cracking process of using, and these two kinds of cleavage methods all have shortcoming separately.

Using alkali is the industrial process that reclaims DMC the earliest from the waste silicone rubber cracking as catalyzer.In numerous alkaline catalystss; KOH is that the cracking waste silicone rubber reclaims the most frequently used a kind of alkali catalyst of DMC; When using KOH as the depolymerization catalyzer, the DMC quality that obtains is higher, and equipment corrosion is also little; But there is the problem of following several respects in this technology: the one, and the consumption of catalyzer is big, produces the thick DMC of 1t and need consume 700～750kg KOH; The 2nd, poor stability because it is acute excessively to be prone in the reaction kettle that local reaction takes place, thereby may cause burning and explosion hazard; The 3rd, accommodation is little, and the KOH of employing only is applicable to depolymerization button class scrap stock and mold glue as catalyzer, is not suitable for glass cement.The 4th, MM value content is higher relatively, and the flash-point of the DMC of recovery is reduced, and viscosity reduces.Though can improve productive rate and add solvent, from all not using and industriallization economically with in the environmental protection.

Acid catalyzed process is the technology that domestic many in recent years producers generally adopt, and main catalyzer is a sulfuric acid, and this technology generally can be divided into sulphuric acid catalysis method and dilute sulphuric acid catalysis method again.Adopt the sulphuric acid catalysis method, the great advantage of this method is almost to be not counted in cost because the sulfuric acid usage quantity is few, but owing to have that equipment corrosion is serious, the equipment replacement rate is big and problem such as sulfur waste s.t. difficulty, the comprehensive cost of actual production is also very high; On the other hand, the DMC recovery of sulphuric acid catalysis method is also low, and extremely unstable.The button class scrap stock good for quality, that polysiloxane level is high, the average yield of DMC is merely 40%～45%; For with a kind of waste silicone rubber, the fluctuation range maximum of its recovery can reach about 15%.When adopting the dilute sulphuric acid catalysis method; The DMC recovery is higher, sulfuric acid is inexpensive and the reusable advantage of ability though this technology has; But keep away also that unavoidable equipment corrosion is serious, the equipment replacement rate big and problem such as sulfur waste s.t. difficulty, and after adopting this technology, the cycle stretch-out of catalytic pyrolysis; Single still reaction needs more than 10 hours approximately, so plant factor is also low.In a word, although though adopt sulfuric acid catalysis method cracking waste silicone rubber gentleer than base catalysis method on technology, the possibility of burning, exploding is less, produces relatively safe; Pipeline is prone to obstruction, equipment corrosion is serious and spent acid is difficult to problems such as processing but exist, and more important is that product DMC forms instability, and various an organosilane monomer content are bigger, and quality is also poor, makes production marketing be affected.

Three, summary of the invention

The present invention is directed to the defective of liquid acid catalytic pyrolysis waste silicone rubber, aim to provide the method that a kind of new waste silicone rubber is recycled, technical problem to be solved is to replace liquid acid catalytic pyrolysis waste silicone rubber with complex solid superacid.

The alleged complex solid superacid (being called for short solid acid down) of the present invention is by support materials fixed mineral acid.Described support materials is selected from Fe ₂O ₃, TiO ₂, Al ₂O ₃, ZrO ₂Or SnO ₂Deng in one or more mixing materials, described mineral acid is selected from sulfuric acid, nitric acid or phosphoric acid etc.

Technical scheme of the present invention comprises preparation, waste silicone rubber catalytic pyrolysis and the aftertreatment of solid acid and separates each unit process; Difference with the prior art is that described catalytic pyrolysis is that waste silicone rubber after pulverizing is mixed afterwards in 120-150 ℃ of cracking 3-4 hour with solid acid catalyst; In the waste silicone rubber quality; The solid acid catalyst that adds 0.5-5%, fractionation by distillation after the scission reaction is collected bullion DMC; Described aftertreatment is in bullion DMC, to add inorganic acid catalyst in 100-140 ℃ of reaction 2-3 hour; Add the alkaline solution termination reaction then; In bullion DMC quality; Add 1mol/L mineral acid 0.1-1%, the alkaline solution add-on of 1mol/L is 0.1-1%, and rectifying separation obtains high-quality DMC after the termination reaction.

The concrete operations step is following:

Be added to the water respectively with metallic compound proportion of composing a certain amount of, control pH value is until settled solution; Stir fast down to the mixed solution and dripping ammonia soln, to the pH of solution about 9, gained solution is placed ageing; The sulphuric acid soln dipping 30min of back with 1mol/L pulverized in for some time after-filtration, washing and oven dry, refilters; Oven dry, sieve (100 order), last roasting makes solid acid.

With pulverizing back waste silicone rubber micelle and the solid acid catalyst that makes in proportion after stirring mixer mixes; Add the scission reaction still; Heating under agitation, control cracking temperature are at 120-150 ℃, and bullion DMC is collected in distillation after cracking 3-4 hour; Go out to heat up in a steamer basically after 6-8 hour and stop, taking advantage of heat release cracked residue.The mineral acid of adding catalytic amount is heated to 100-140 ℃ among the bullion DMC that obtains, and reacts to add small amount of alkali after 2-3 hour, and filtered while hot is removed insolubles, is obtaining high quality DMC through rectifying.

Among the bullion DMC that cracking is reclaimed, add the mineral acid of catalytic amount, after the reaction regular hour, add the alkaline agent termination reaction, just can obtain the DMC of low MM content through rectifying.Why the mineral acid that adds catalytic amount can remove MM, is owing to reclaim MM among the DMC under the small amounts of inorganic acid catalyst, and easy the fracture again and monomer reaction such as Dn can effectively be reduced MM content, and reaction mechanism is following:

(n≥4；m≥4)

When catalyzer is removed MM, remove the bigger D of tension force ₃Outward, the preferential attack of catalyzer be the stronger M chain link of alkalescence, speed of response is in proper order: D ₃＞MM＞MDM＞MD ₂M＞D ₄And do not contain D basically among the DMC that reclaims ₃So when carrying out catalyzed reaction, at first cracked is MM, so just can reach the purpose of preferential decomposition MM content.

The present invention uses complex solid superacid as catalyzer, has at first overcome to use alkali as some problems that catalyzer brought, and, poor stability big like the consumption of catalyzer and accommodation are little; Secondly, not only has the catalytic advantage of liquid acid, shortcoming such as overcome also that the pipeline that uses liquid acid to bring is prone to stop up, spent acid is handled difficulty and equipment corrosion is serious.

Through the DMC that the present invention reclaims, its recovery can be stablized in Zylox and reaches more than 50%; Wherein the content of MM can be controlled in below 0.01%, and the quality of Zylox is synthesized and can not influenced in the polymerization that can directly apply to Zylox.

Four, embodiment

Instance 1SO ₄ ^2-/ Al ₂O ₃-TiO ₂The preparation of complex solid superacid

With mass ratio 1: 1 1kg TiCl ₄, AlCl ₃Be added to the water respectively, control pH value is until settled solution; Stir fast down to the mixed solution and dripping ammonia soln, to the pH of solution about 9, gained solution is placed ageing; The sulphuric acid soln dipping 30min of back with 1mol/L pulverized in after-filtration, washing and oven dry in 4 hours, refilters; Oven dry, sieve (100 order), last roasting makes SO ₄ ^2-/ Al ₂O ₃-TiO ₂Compound solid-acid.

Instance 2SO ₄ ^2-/ Fe ₂O ₃-TiO ₂The preparation of complex solid superacid

With mass ratio 1: 1 1kg FeCl ₃, TiCl ₄Be added to the water respectively, control pH value is until settled solution; Stir fast down to the mixed solution and dripping ammonia soln, to the pH of solution about 9, gained solution is placed ageing; The sulphuric acid soln dipping 30min of back with 1mol/L pulverized in after-filtration, washing and oven dry in 4 hours, refilters; Oven dry, sieve (100 order), last roasting makes SO ₄ ^2-/ Fe ₂O ₃-TiO ₂Compound solid-acid.

Instance 3 cracking button class scrap stock class waste silicone rubbers prepare DMC

With button class scrap stock waste silicone rubber micelle 400g and the 3gSO after pulverizing ₄ ^2-/ Al ₂O ₃-TiO ₂Composite solid-acid catalyst adds the scission reaction still after stirring mixer mixes, heating under agitation, and the control cracking temperature is about 130 ℃, and cracking begins distillation and collects bullion DMC after 4 hours, and stopped reaction after 7 hours is taken advantage of heat release cracked residue.In the bullion DMC that distills out (about 250g), adding 0.5g 1mol/L sulfuric acid, be heated to 120 ℃, react the terminator KOH aqueous solution that adds 0.5g1mol/L after 2 hours, obtaining high-quality DMC (about 200g), wherein D through rectifying ₄About 156g, D ₅About 20g, D ₆About 10g, D _＞7About 14g, the content of MM is below 0.01%.

Instance 4 cracking glass cement class waste silicone rubbers prepare DMC

With button class scrap stock waste silicone rubber micelle 400g and the 3gSO after pulverizing ₄ ^2-/ Fe ₂O ₃-TiO ₂Composite solid-acid catalyst adds the scission reaction still after stirring mixer mixes, heating under agitation, and the control cracking temperature is about 130 ℃, and cracking begins distillation and collects bullion DMC after 4 hours, and stopped reaction after 7 hours is taken advantage of heat release cracked residue.In the bullion DMC that distills out (about 250g), adding 0.5g 1mol/L nitric acid, be heated to 120 ℃, react the terminator NaOH aqueous solution that adds 0.5g1mol/L after 2 hours, obtaining high-quality DMC (about 200g), wherein D through rectifying ₄About 146g, D ₅About 24g, D ₆About 20g, D _＞7About 10g, the content of MM is below 0.01%.

Claims

1. the recoverying and utilizing method of a waste silicone rubber; Comprise preparation, waste silicone rubber catalytic pyrolysis and the aftertreatment of solid acid and separate each unit process; It is characterized in that: described catalytic pyrolysis is that waste silicone rubber and the solid acid catalyst after pulverizing mixed the back in 120-150 ℃ of cracking 3-4 hour, in the waste silicone rubber quality, adds the solid acid catalyst of 0.5-5%; Fractionation by distillation after the scission reaction is collected bullion ring dimethyl siloxane; Described aftertreatment is in bullion ring dimethyl siloxane, to add inorganic acid catalyst in 100-140 ℃ of reaction 2-3 hour; Add the alkaline solution termination reaction then; In bullion ring dimethyl siloxane quality; Add 1mol/L mineral acid 0.1-1%, the alkaline solution add-on of 1mol/L is 0.1-1%, and rectifying separation obtains high-quality ring dimethyl siloxane after the termination reaction; Described solid acid is that described support materials is selected from Fe by support materials fixed mineral acid ₂O ₃, TiO ₂, Al ₂O ₃, ZrO ₂Or SnO ₂In one or more mixing materials, preparation during solid acid employed mineral acid be selected from sulfuric acid, nitric acid or phosphoric acid.