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US4397756A Expired / Lapsed US ⏱️ 0.0 years remaining

Method and composition for reduction of formaldehyde emission in wood composite panels

Assignee: Weyerhaeuser Co
•
Filing: 1981-08-10
•
Granted: 1983-08-09
•
Expires: 2001-08-10
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Abstract

Abstract The invention is a composition of matter and method for its use in reducing formaldehyde emission from wood composite panels bonded with aminoplast resins. The preferred composition comprises urea, a carbohydrate based material such as cooked or gelatinized starch, and an acidic catalyst for the resin. The ratio of urea to carbohydrate based material is in the range of 10:1 to 40:1 while the urea forms from 20-60% of the composition. In use, the composition is preferably sprayed on the wood particles, flakes or fiber in the blender at the same time resin is added. Typical usage is 0.4-3 parts, on a urea basis, added to each 100 parts of dry wood substance. Depending on several factors, the reduction in formaldehyde emission ranges from 60-90% without serious deterioration occurring in any other product physical properties.

Inventors

  • 👤 William F. Lehmann

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-10-27 12:49
CPC Classifications
C; C08; C08L; C08L97/00; C08L97/02; C08G; C08G16/00; C08G16/02; C08G16/0293; C08L61/00; C08L61/20; Y; Y10; Y10T; Y10T428/00; Y10T428/25; Y10T428/253; Y10T428/31504; Y10T428/31942; Y10T428/31949; Y10T428/31957; Y10T428/31971; Y10T428/31975; Y10T428/31978; Y10T428/31982; Y10T428/4935; Y10T428/662

Claims Analysis

Total Claims: 7
Claim 1
Independent Claim 69 words
A composition of matter comprising 20-60% urea; 0.5-5% of a carbohydrate based material selected from the group of sugars, starches, water-soluble or water-dispersable cellulose derivatives, or mixtures thereof; 0.5-5% of an acidic salt effective as a thermosetting aminoplast resin curing agent, and 0-2% formaldehyde based on the amount of urea present and where the ratio of urea to carbohydrate based material is in the range of 10:1 to 40:1.
Claim 2
Dependent Claim 69 words
A composition of matter comprising 20-60% urea; 0.5-5% of a carbohydrate based material selected from the group of sugars, starches, water-soluble or water-dispersable cellulose derivatives, or mixtures thereof; 0.5-5% of an acidic salt effective as a thermosetting aminoplast resin curing agent, and 0-2% formaldehyde based on the amount of urea present and where the ratio of urea to carbohydrate based material is in the range of 10:1 to 40:1.
Claim 3
Dependent Claim 25 words
The composition of claim 1 in which the acidic salt is selected from the group of ammonium chloride, ammonium sulfate, ammonium nitrate, or mixtures thereof.
Claim 4
Dependent Claim 20 words
The composition of claim 1 in which a buffer is additionally present to stabilize pH in the range of 5.0-6.0.
Claim 5
Dependent Claim 18 words
The composition of claims 1, 2, or 3 in which the carbohydrate based material is a cooked starch.
Claim 6
Dependent Claim 37 words
An aqueous composition of matter comprising 35-45% urea; 1-2% cooked starch; 1-2% of an acidic salt from the group of ammonium chloride, ammonium sulfate, ammonium nitrate, or mixtures thereof; 0-2% formaldehyde based on urea; and 0-0.8% triethylamine.
Claim 7
Dependent Claim 37 words
An aqueous composition of matter comprising 35-45% urea; 1-2% cooked starch; 1-2% of an acidic salt from the group of ammonium chloride, ammonium sulfate, ammonium nitrate, or mixtures thereof; 0-2% formaldehyde based on urea; and 0-0.8% triethylamine.

References Cited (Backward Citations)

US4238545A Cited
US4244846A Cited

USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1986-08-08 1987-02-07 1987-08-09 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 1990-08-08 1991-02-07 1991-08-09 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 1994-08-08 1995-02-07 1995-08-09 $7700.00 Window Closed / Lapsed

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