SE436329B

SE436329B - Method to reduce emissions of formaldehyde from carbamide resin bound chipboards

Info

Publication number: SE436329B
Application number: SE8105529A
Authority: SE
Inventors: A W Westling
Original assignee: Swedspan Ab
Priority date: 1981-09-18
Filing date: 1981-09-18
Publication date: 1984-12-03
Also published as: SE8105529L

Abstract

A method of reducing emissions of formaldehyde from carbamide resin shavings by covering the shavings, after pressing, with a solution of ammonium carbonate and/or ammonium hydrogen carbonate, and possibly urea, and the stacking of the shavings treated in this way for maturing in storage. According to the invention, the application of the solution of ammonium carbonate and/or ammonium hydrogen carbonate, and possibly urea, is only carried out when the shavings have attained a temperature of around 10 - 35 degrees C, preferably 20 - 30 degrees C.

Description

8105529-5 kännetecknas av att skivornaefter pressningen kyls till en för mognadslagring konventionell temperatur och staplas för mognadslagring, att skivorna, när de nått en temperatur i om- rådet 10-35°C, företrädesvis 20 - 30°C uttages ur stapeln, be- sprutas med lösningen och åter staplas. > Skivornas temperatur vid behandlingen är vanligen något högre än omgivningens, exempelvis 5 - 10°C högre än omgiv- ningens, när den senare ligger vid ca 10 - 25°C och behandlingen genomföres hos skivtillverkaren. Härvid avses med skivornas temperatur den temperatur som råder inne i stapelns mitt strax före behandlingen och med omgivningens temperatur den tempera- tur som råder i den lokal i vilken de staplade skivorna lag- ras. 7 Den nya stapeln lämnas i fred omkring ett dygn eller mer för att förutom bindning av fri formaldehyd uppnå konditione- ring av skivorna. Efter konditioneringen företages slipning av skivorna. 8105529-5 is characterized in that the discs are cooled to a conventional temperature for maturation after pressing and stacked for maturation storage, that the discs, when they have reached a temperature in the range 10-35 ° C, preferably 20 - 30 ° C are removed from the stack, sprayed with the solution and stacked again. > The temperature of the discs during treatment is usually slightly higher than that of the environment, for example 5 - 10 ° C higher than that of the environment, when the latter is at about 10 - 25 ° C and the treatment is carried out at the disc manufacturer. The temperature of the discs refers to the temperature prevailing in the middle of the stack just before the treatment and by the ambient temperature the temperature prevailing in the room in which the stacked discs are stored. 7 The new stack is left in peace for about a day or more in order to achieve conditioning of the discs in addition to binding free formaldehyde. After conditioning, the discs are ground.

Uppfinningen kommer i det följande att belysas med hjälp av ett antal utföringsexempel.The invention will be elucidated in the following with the aid of a number of embodiments.

EXEMPEL 1 Karbamidhartsbundna spånskivor med en nominell tjocklek av 22 mm framställdes genom pressning av bindemedelsbehandlat spån, kyldes till ca 50-60°C och staplades. Efter 5 h uttogs en skiva ur stapeln och delades i provbitar om 300 x 400 mm, vilka efter att ha antagit rumstemperatur (ca ZOOC) bespruta- des med en läsning innehållande 10 % (vikt/volym) ammonium- vätekarbonat, 10 % (vikt/volym) ammoniumkarbonat och 9 % (vikt/ volym) urea i vatten, varvid besprutningen skedde med 160 ml lösning/m2 och sida. Två staplar om vardera fem provbitar upp- rättades och förvarades 24 resp. 72 h vid 20°C. Därefter av- slipades 0,4 mm på vardera sidan av varje provbit för erhållan- de av 22 mm slipade skivor (provbitar).EXAMPLE 1 Urea-bonded chipboard with a nominal thickness of 22 mm was prepared by pressing binder-treated chips, cooled to about 50-60 ° C and stacked. After 5 hours, a slice was removed from the stack and divided into 300 x 400 mm test pieces, which after assuming room temperature (about ZOOC) were sprayed with a solution containing 10% (w / v) ammonium bicarbonate, 10% (w / w). / volume) ammonium carbonate and 9% (w / v) urea in water, spraying with 160 ml solution / m2 and side. Two stacks of five test pieces each were set up and stored 24 and 24, respectively. 72 hours at 20 ° C. Then 0.4 mm was ground on each side of each test piece to obtain 22 mm ground discs (test pieces).

EXEMPEL 2 Skivor framställdes och behandlades på samma sätt som i exempel 1 ovan, men provbitarna besprutades med en vattenlös- ning endast innehållande ammoniumvätekarbonat i en koncentra- tion av 10 % vikt/volym) med 160 ml lösning/m2 och sida. 8105529-5 EXEMPEL 3 Oslipade s.k. fuktbeständiga spånskivor (framställda med användning av melamin-urea-formaldehyd-kondensat som binde- medel) med en storlek av 30 x 40 cm och en nominell tjocklek av 22 mm besprutades med 160 ml/m2 och sida av en lösning enligt exempel 1, varefter de arrangerades i en stapel om fem skivor, förvarades 24 h vid 20°C och därefter slipades till 22 mm tjocklek.EXAMPLE 2 Discs were prepared and treated in the same manner as in Example 1 above, but the specimens were sprayed with an aqueous solution containing only ammonium bicarbonate at a concentration of 10% w / v) with 160 ml solution / m2 and side. 8105529-5 EXAMPLE 3 Oslipade s.k. Moisture-resistant particle boards (prepared using melamine-urea-formaldehyde condensate as binder) with a size of 30 x 40 cm and a nominal thickness of 22 mm were sprayed with 160 ml / m2 and side of a solution according to Example 1, after which they were arranged in a stack of five discs, stored for 24 hours at 20 ° C and then ground to 22 mm thickness.

EXEMPEL A Skivor behandlade enligt exemplen 1 ~ 3 och motsvarande obehandlade skivor undersöktes med avseende på halten fri formaldehyd enligt FESYP-perforatormetod (British Standard 1811l.Resultaten återges i tabellen nedan. Som "Ref. 1" be- tecknas obehandlade skivor av den typ som använts vid exemplen 1 och 2 och som “Ref. 2" obehandlade fuktbeständiga skivor av den typ som använts vid exempel 3.EXAMPLE A Discs treated according to Examples 1 ~ 3 and corresponding untreated discs were examined for the content of free formaldehyde according to the FESYP perforator method (British Standard 1811l. The results are given in the table below. "Ref. 1" refers to untreated discs of the type used in Examples 1 and 2 and as "Ref. 2" untreated moisture-resistant boards of the type used in Example 3.

TABELL Skivor enligt Lagring Fri formaldehyd exempel nr h mg/100 g skiva 1 24 h 7 1 72 h 5 2 24 h - 12 2 72 h 14 Ref.1 - 25 3 24 h 19 Ref.2 - 46TABLE Discs according to Storage Free formaldehyde example no. H mg / 100 g disc 1 24 h 7 1 72 h 5 2 24 h - 12 2 72 h 14 Ref.1 - 25 3 24 h 19 Ref.2 - 46

Claims

8105529-5 _ PATENT REQUIREMENTS

Methods of reducing the emission of formaldehyde from urea-bonded particle boards by coating the boards after pressing with a solution of ammonium carbonate and / or ammonium bicarbonate and possibly urea and stacking of the thus treated slices for maturation storage, it can be seen that the coating with said solution is carried out only after the slices have assumed a temperature in the range 10 - 35 ° C, preferably 20 - 30 ° C.

2. A method according to claim 1, characterized in that the discs are cooled to a conventional temperature for maturation after pressing and stacked for maturation storage, that the discs, when they have reached a temperature in the range 10 - 35 ° C, are preferably removed from 20 - 3000 out of the stack, sprayed with the solution and stacked again. 810552945 SUMMARY A way to reduce the emission of formaldehyde from urea-bonded chipboard by coating the boards after pressing with a solution of ammonium carbonate and / or ammonium bicarbonate and possibly urea and stacking of the thus treated slices for maturation storage. According to the invention, the coating is carried out with the solution of ammonium carbonate and / or bicarbonate and possibly urea only after the disks have assumed a temperature in the range 10 - 3s ° c, preferably zo - 3o ° c.