US4009048A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Solvent cleaning and recovery process
Assignee: PACIFIC WESTERN RESIN Co
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Filing: 1975-07-11
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Granted: 1977-02-22
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Expires: 1995-07-11
Abstract
Abstract Vinyl halide polymers are removed from the internal surfaces of reaction equipment with a solvent and the solvent recovered by: (1) contacting the polymer-containing solvent with steam forming a slurry; (2) cooling the slurry to form a crumbly precipitate; (3) separating the resulting slurry into an aqueous solvent and a precipitate; (4) adding water to the precipitate to form a second slurry; and (5) separating the second slurry into a second aqueous solvent solution and vinyl halide polymers. The aqueous solvent solutions are dehydrated before being reused in solvent cleaning.
Inventors
- 👤 Bruce E. Jensen
- 👤 Jimmie G. Tolar
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 05:37
CPC Classifications
B; B08; B08B; B08B9/00; B08B9/08; B08B3/00; B08B3/04; B08B3/08; B08B3/10
Claims Analysis
Total Claims: 25
Claim 1
Independent Claim
72 words
In a process for solvent cleaning polymerization reaction equipment to remove vinyl halide polymers from the internal surfaces thereof which comprises contacting said internal surfaces with a solvent for said vinyl halide polymers heated to an elevated temperature, said solvent having an atmospheric boiling point above 100° C, and removing a solution containing the vinyl halide polymers dissolved in said solvent from said reaction equipment, the improvement which comprises the steps of:
Claim 2
Dependent Claim
72 words
In a process for solvent cleaning polymerization reaction equipment to remove vinyl halide polymers from the internal surfaces thereof which comprises contacting said internal surfaces with a solvent for said vinyl halide polymers heated to an elevated temperature, said solvent having an atmospheric boiling point above 100° C, and removing a solution containing the vinyl halide polymers dissolved in said solvent from said reaction equipment, the improvement which comprises the steps of:
Claim 3
Dependent Claim
89 words
contacting said solution with steam in a vessel to precipitate substantially all of the vinyl halide polymers from said solution to form a first slurry comprising said vinyl halide polymers in an aqueous solution of said solvent and water, said first slurry containing greater than about 6% by weight water and having a temperature within the range of about 75° to 120° C. 2. cooling said first slurry from step (1) to a temperature less than the highest temperature obtained during step (1) sufficient to form a crumbly precipitate,
Claim 4
Dependent Claim
89 words
contacting said solution with steam in a vessel to precipitate substantially all of the vinyl halide polymers from said solution to form a first slurry comprising said vinyl halide polymers in an aqueous solution of said solvent and water, said first slurry containing greater than about 6% by weight water and having a temperature within the range of about 75° to 120° C. 2. cooling said first slurry from step (1) to a temperature less than the highest temperature obtained during step (1) sufficient to form a crumbly precipitate,
Claim 5
Dependent Claim
63 words
separating the cooled first slurry from step (2) into a first aqueous solvent solution and a precipitate, 4. adding water to said precipitate from step (3) with agitation to form a second slurry, 5. separating said second slurry into a second aqueous solvent solution and vinyl halide polymers, and 6. dehydrating at least one of said aqueous solvent solutions to recover said solvent.
Claim 6
Dependent Claim
63 words
separating the cooled first slurry from step (2) into a first aqueous solvent solution and a precipitate, 4. adding water to said precipitate from step (3) with agitation to form a second slurry, 5. separating said second slurry into a second aqueous solvent solution and vinyl halide polymers, and 6. dehydrating at least one of said aqueous solvent solutions to recover said solvent.
Claim 7
Dependent Claim
43 words
The process of claim 1 wherein said solvent is selected from the group consisting of tetramethyl urea, dimethylacetamide, N-methylpyrrolidone, dimethyl formamide, and diethyl formamide, and wherein the temperature during step (1) is increased to within the range of about 75° to 120° C.
Claim 8
Dependent Claim
38 words
The process of claim 2 wherein said first slurry from step (1) is cooled to a temperature of less than 75° C before it is separated into said first aqueous solvent solution and said precipitate in step (3).
Claim 9
Dependent Claim
25 words
The process of claim 3 wherein said first slurry from step (1) is cooled to a temperature in the range of 30° to 65° C.
Claim 10
Dependent Claim
34 words
The process of claim 1 wherein sufficient steam is added during step (1) so that the water content within said vessel is increased to within the range of about 8 to 18% by weight.
Claim 11
Dependent Claim
16 words
The process of claim 1 wherein the contents of the vessel is agitated throughout step (1).
Claim 12
Dependent Claim
17 words
The process of claim 1 wherein said steam contains 0.1 to 60% by weight of entrained water.
Claim 13
Dependent Claim
35 words
The process of claim 1 wherein said vinyl halide polymers are vinyl chloride polymers and said solution containing the vinyl chloride polymers is stripped to remove any hydrochloric acid contained therein prior to step (1).
Claim 14
Dependent Claim
27 words
The process of claim 1 wherein each of said aqueous solvent solutions is dehydrated and wherein the resulting dehydrated solvent is recovered for reuse in solvent cleaning.
Claim 15
Dependent Claim
29 words
The process of claim 9 wherein each of said aqueous solvent solutions is combined and fractionally distilled to remove substantially all of the water contained in the combined stream.
Claim 16
Dependent Claim
11 words
The process of claim 1 wherein said solvent is dimethyl formamide.
Claim 17
Dependent Claim
31 words
The process of claim 1 wherein an amount of water is added during step (4) so that said second slurry has a water to precipitate weight ratio of 1:1 to 6:1.
Claim 18
Dependent Claim
96 words
In a process for solvent cleaning polymerization reaction equipment to remove vinyl halide polymers from the internal surfaces thereof which comprises contacting said internal surfaces with a solvent for said vinyl halide polymers selected from the group consisting of tetramethyl urea, dimethylacetamide, N-methylpyrrolidone, dimethyl formamide, and diethyl formamide, heated to a temperature in the range of from about 70° to 150° C, said solvent having an atmospheric boiling point about 100° C and removing a solution containing the vinyl halide polymers dissolved in said solvent from said reaction equipment, the improvement which comprises the steps of:
Claim 19
Dependent Claim
96 words
In a process for solvent cleaning polymerization reaction equipment to remove vinyl halide polymers from the internal surfaces thereof which comprises contacting said internal surfaces with a solvent for said vinyl halide polymers selected from the group consisting of tetramethyl urea, dimethylacetamide, N-methylpyrrolidone, dimethyl formamide, and diethyl formamide, heated to a temperature in the range of from about 70° to 150° C, said solvent having an atmospheric boiling point about 100° C and removing a solution containing the vinyl halide polymers dissolved in said solvent from said reaction equipment, the improvement which comprises the steps of:
Claim 20
Dependent Claim
157 words
contacting said solution with steam in a vessel until the temperature within said vessel is in the range of about 75° to 120° C and the water content is in the range of about 8 to 18% by weight to precipitate substantially all of the vinyl halide polymers from said solution, and to form a first slurry comprising said vinyl halide polymers in an aqueous solution of said solvent and water, 2. cooling said first slurry to a temperature of less than 75° C to form a a crumbly precipitate, 3. separating the cooled first slurry from step (2) into a first aqueous solvent solution and a precipitate, 4. adding water to said precipitate from step (3) with agitation to form a second slurry, 5. separating said second slurry into a second aqueous solvent solution and vinyl halide polymers, and 6. dehydrating each of said aqueous solvent solutions and recovering the solvent for reuse in solvent cleaning.
Claim 21
Dependent Claim
157 words
contacting said solution with steam in a vessel until the temperature within said vessel is in the range of about 75° to 120° C and the water content is in the range of about 8 to 18% by weight to precipitate substantially all of the vinyl halide polymers from said solution, and to form a first slurry comprising said vinyl halide polymers in an aqueous solution of said solvent and water, 2. cooling said first slurry to a temperature of less than 75° C to form a a crumbly precipitate, 3. separating the cooled first slurry from step (2) into a first aqueous solvent solution and a precipitate, 4. adding water to said precipitate from step (3) with agitation to form a second slurry, 5. separating said second slurry into a second aqueous solvent solution and vinyl halide polymers, and 6. dehydrating each of said aqueous solvent solutions and recovering the solvent for reuse in solvent cleaning.
Claim 22
Dependent Claim
25 words
The process of claim 13 wherein said first slurry from step (1) is cooled to a temperature in the range of 30° to 65° C.
Claim 23
Dependent Claim
17 words
The process of claim 14 wherein said steam contains 0.1 to 60% by weight of entrained water.
Claim 24
Dependent Claim
11 words
The process of claim 15 wherein said solvent is dimethyl formamide.
Claim 25
Dependent Claim
38 words
The process of claim 13 wherein the contents of the vessel is agitated throughout step (1) at a sufficient speed so that the vinyl halide polymers that have precipitated from said solution remain as discrete, easily separable particles.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-02-22 | 1980-08-23 | 1981-02-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-02-22 | 1984-08-23 | 1985-02-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-02-22 | 1988-08-23 | 1989-02-22 | $7700.00 | Window Closed / Lapsed |