CA1098508A - Reactive catalyst for amino resins - Google Patents

Abstract

A reaction catalyst for the polycondensation of amino resins used for bonding water-penetrable cellulosic particles is disclosed. Said catalyst, if used in combination with a known catalyst, increases the rate of polycondensation of the resin while at the same time allowing the use of lower amounts of resin solids without imparting any loss in bonding strength. The catalyst comprises a concentrated aqueous solution of a mixture of organic and inorganic components, the organic components being formaldehyde and urea or a non resinous condensation product of formaldehyde and urea, and the inorganic component being a water-soluable alkali metal halide.

Description

s~
The present invention relates to a reactive ca~a]~st:
comprisecl of mixture of organ;c and inorganic componerlts, whereby the addition of such a catalyst to amino resins used for bonding water-penetrable cellulosic particles, allows lower amounts of resin solids to be used while at the same time increasing the rates of production without imparting any loss in bonding strength.
~- The said catalyst is comprised mainly of an or~
ganic and an inorganic component. The organic component is a concentrated solution of formaldehyde with urea (said solution of formaldehyde with urea is comprised of the monomers or of a non resinous condensation product of these - monomers)~ while the inorganic component is an alkali halide.
The curing rate is increased at high tempera-tures to such levels as may never be reached by the simple addi-tion of acid-curing catalysts. The addition of acid-curing catalysts increases the curing rate, but such a level is then reached whereby further increase causes the degrada-tion of the properties of the bonded materialO
Furthermore, the addition of the well-known cata-lysts to higher levels allows the polycondensation to pro-ceed even at room temperature (in spite of the addition of retarders such as ammonia or hexamethylenetetramine) This reduces the shelf life of the glue at room temperature, causing precuring before the introduction of the mat in the press and resulting in the well-known handicaps of such a phenomenon.
The addition, however~ of the catalyst according to the present invention may increase even further the curing rates and subsequently reduce pressing times, without causing any degradation of the properties of the bonded material. The addition of said catalyst reacts only at high temperatures. It therefore substantially increases the polycondensation rates of the resin at the temperature of the press without increasing it at all at room temperatures, thus avoiding any precuring problems.
The said catalyst is combined with, and becomes part of, the resin itself.
The combination of an organic with an inorganic component in the catalyst exhibits a synergic behaviour.
:
If the single components are added alone to the resin they do exhibit a certain increase in the curing rate, but when added in a comblnatLon, they exhibit an increase~which is higher than the sum of the results obtained when each component is added separately.
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The halide~salt may be any soluble hallde of an alkali metal.
20 ~ The or~anic material may be a non~resinous condensate of urea with-formaldehyde.
- i -: :
Ik~is preferable to also add;~a~surface active agent to the catalyst in small quantities,~such as 0.1-2%, to imprRve the~re~sln~dlspersion.
The catalyst according to the present invention (calculated as 100 % solids content) may be added in various proportions and more precisely 1 to 30 % of the resin so~
: . .
~ lids used. The most important aspect of khe present inven- ~

:~ : :; ~ :

tion is the f`act that the said catalyst may substitute part of the resin without lowering the properties of the final product. This is achieved not by adding the catalyst in quantities equal to the quantity of resin substituted~
but by adding said catalyst in quantities from 50 to 70 %
of the amount of resin substituted (calculations referred to by weight and referring to all product;s as 100 % so~
lids).
The catalyst according to the present invention may, because of its syner~ic behaviour, substitute the resin in quantities up to twice its own weight. The above rnentioned characteristic of said catalyst is exhibited for an addition of up to 20 % of the weight of the resin, corres-ponding to a substitution of up to 40 % of the weight of the used resin.
When added to lower amounts e.g. 3 to 10 % there is a considerable increase in the properties of the end product.
When added to higher levels i.e. up to 30 %, no difference is imparted to the properties of the end pro-duct but it conside~rably increases the curlng rates and the resin saved~
Bonding is effected by curing the resin at elevat-ed temperatures and pressures according to the methods well known in the art. The catalyst may be used in all types of products where amino resins are used for bonding lignocel-lulosic products, whether these are wood particles for par ticleboard production using flat press~ or calender or wood veneers such as in plywood production.
The quality of' boards produced was controlled weekly f'or a period of six months and no reduction in the properties was observed, This proves that no polymer degradation occurs and that the ageing properties of the boards are compar-able to the ones normally produced.
Substituents so far known in the art to substi-tute resin have not succeeded in keeping the same methods , lO of production well known in the ark for the h1gher substi-tutions while they have not conferred a simultaneous in-crease in the speed of production, In particular~ the known~substituents are hali.de , .
salts without using the mixture of halide salt with the 15 ~ urea and formaldehyde additions.
The addit1on~of the halide salt alone succeeds ; in substituting part of the resin with the following limi-tations as~compared to the :reactive catalyst accord1ng to khe present~invention.
~ The rate~of production is not increased, in case of higher substitutions it~is actually~decreased~ the :: : : : : : ~ : :: : : :
substituents~acting as retarders instead of~as catalysts because of the high amount of water present.
~2.~Substitution is obta1ned in ratios of~
while in the case of the reactive catalyst according to the present invention it is up to 1:2, 3, Higher substitutions are obtained by means of a separate spraying of wood with the halide salt solu-, , ~ , . . .

~85i~

tion with subsequent drying fol:lowed by spraying of the adhesive. In the case of the reactive catalyst according to the present invention, higher substitutions are obtai-ned without the need to spray the reactlve catalyst sepa-rately and dry subsequently. The reactive catalyst is added co the resin solution and this solution is used to spray the wood furnish In one step according to the me-thods well known in the art.
The reactive catalyst according to the present invention provides yet another advantage.
Due to the lower quantity of resin used and im-- proved performance achieved, the amount of free formalde-hyde in the production hall and boards is considerably reduced and the boards resulting are nearly odourless.
The followin~ examples are presented in illustra-t:ion of the invention and are not intented as limitations.

Example l ~
A constant amount of urea formaldehyde resin ; (BASF 285) is~reacted~ under controlled conditions of tem-perature and pressure with the catalyst according to the present invention, said catalyst varying according to the :
proportions of the constituents making up the oatalyst solution.
The latter ls not used alone but in addition to the usual catalyst well known in the art, which consists :
~usuaIly of ammonium chloride, comprising hexamethylenetetr-amine or not.

' ' ' : . , In table No. 1 the synergic effect of the cata-lyst solution comprised of the organic and inorganic com-ponents is clearly illustrated.
Sample 1 which is considered ~o be the blank and does not include the cata]yst solution according to the present invention but only the we~-known ammonium chloride as a cakalyst, has a gel time of 90 seconds at 100 C.
Sample 2 comprises, apart from ammonium chloride, also a cetain quantity of urea~formaldehyde, and exhibits a slightly increased catalytic effect with a gel time of 85 seconds at 100 C.
Sample 3 comprises~ apart from ammonium chloride, -also a certain quantity of sodium chloride but no urea formaldehyde, and exhibits a slightly increased catalytic effect with a gel time of 80 seconds at 100 C
Sample ll comprises, apart from ammonium chloride, .
a mixture of urea formaldehyde with sodium chloride, the total sum of the mixture added being equal to the amount of the single components added in samples 2 and 3. Samples ~4, 5 and 6 present an increased catalytlc e;ffect, due~to :. ~ : : :
the synergic behaviour of the componentes used and the gel times obtained at 100 C are 60,~35~and~ 28 seconds respec-tively.
The difference between samples 4, 5 and 6 results .
: :
from the ~different proportions of the organic component~
used in comparison to the inorganic component of the cata-lyst solutlon It is noticed that sample 6, comprising the .
_ 7 ': ' ' ' ' ~ 5~

highe:r amount Or organic materi.al, also presents the greater catalyl,ic effect, Table No. 1 .

Components in parts by welght Samples ... . . , _ ; - 5 1 2 3 4 5 6 . Urea formaldehyde resin t65 % solids content) 140 140 lLIo lllo 140 140 Water. 70 lo lo lo lo lo Catalyst solution - 60 60 60 60 60 10 Ammonium chloride :~
~ (20 % solution in water) 12 12 12 12 12 12 Hexamethylenetetramine ~- (20 % solution in water) 8 8 8 8 8 Gel tirne in seconds at 100 C 90 85 80 60 35 28 , . .
15 Gomponents of catalyst solution Parts b ~ eight ; Urea (100 %) :: - 5.35 - ~5.35 10.70 ~16.05 ormaldehyde (100 %? ~ 2.75 - 2.755.50 8.25 Sodium chloride (100~%) - - 20.0 20.020.0 20.0 Surface~active~agent : 20 (10 % solution in water) - ~1.0 1.0 1.0 1.0 1.0 ~ water ~ go.g 79.0 70.9 62.8 54.7 Total ~ 100.0 100.0 100.0 100.0 100.0 ' Example ~2 The~pre,sent example illustrates the:advantages obtained ln the particleboard~ production when the cata~
. lyst according to the present invention is added to the formulation, Three cases are presented whereby the same total quantity of solution is used. TAe differences occur in :

the di~ferent proportions of the various components of the solution used as shGwn in table No,2. It is noted that column A refers to the solution used to spray fine wood dust which is used in turn to form the external surf'aces of the particleboard, while column B refers to the solution used to spray wood f]akes which are used in turn to form the core of the particleboard.
The particleboard is produced in the present example according to the Bison system i.e. with con-tinuous layer ~ormation under controlled conditions which are kept constant for all the cases presented.
Moisture of mat before the press : 10.5 ~ 0,5 %
Press temperature : 210 C
Pressure 35 kg/cm2 -The qualities o~ the particleboard produced do .~
not present any appreciable differences in all three cases.
(See results in table 2).
The various solutions prepared in the three ca-ses according to the presen~ example succeed in reducing the pressin~ times as follows:
Sample No.1: 9.25 seconds per mm non sanded particleboard Sample No.2: 8.oo seconds per mm non sanded particleboard Sample No.3: 7.00 seconds per mm non sanded particleboard :
The third sample includes the largest amount of organic component as compared to the inorganic component and presents the most successful results, The present example proves that the use o~ the catalyst according to the present invention makes lt pos-ælble to reduce the pressing time in particleboarù produc-_ g _ tion and simultaneously allows the reduction of resin-usage when using sa;d catalyst by up to 30 %. 16,90 %
(sample 2) or 21 % (sample 3).

Tab_e No. 2 5 Components in parts by weight Samples . .

A B A B A B
Urea formaldehyde resin (65 % solids conterlt) 100.0 200.0 70.0 140.0 70.0:L40.0 Ammonium chloride (20 % solution in water) - 8.o - 8.o - 8.o Water . 68.5 31.0 58.5 20.0 58.5 20.0 Ammonia 25 BAUMÉ 1.5 1.0 1. 5 2.0 1. 5 2.0 Catalyst solution - - 40.0 70.0 40.0 70.0 Total 170.0 240.0 170.0 2LIo. o 170.0240.0 Components of catalyst solution :: Urea (100 %) - - 5.35 5.35 lo-7010.70 ,.. . . .
Formaldehyde (100 %) - - 2.75 2.75 5.50 5.50 Sodium chloride (100 %) ~ - 20.0 20.0 20.0 20.0 Surface actlve agent (10 % solution in water) - - 1.0 .1.0 1.0 ~1.0 : Water -: _ 70.9 70.9 62.862. &

, Total - - 100.0 100.0 100.0100.0 ' Properties Sample Density1kg/m3 660 640 625 Thickness in mm 16,2 16.0 16:.1 Modulus of elasticity L 26000 23200 24000 Tensile strength, kp/cm 5.0 4.5 4.2 Bending strength, kp/cm2 250 230 225 Water absorp~ion~ percent at 24 hours immersion l~o 45 52 Swelling, percent increase at 24 hours immersion 13 15 20 Example 3 The present example illustrates the increase in the rate of particleboard production obtained when the catalyst according to the present invention is added to the formulation (i.e. a mixture of sodium chloride and urea formaldehyde monomers) as compared to the rate ob-tained by the simple addition of sodium chloride (with-out urea formaldehyde monomers).
The results are reported in table 3 where sample 1 contains only sodium chloride apart from the usual addi-tives added to the resin formulation for particleboard - production, and has, therefore, a gel time of 80 seconds :
while sample 2` contains the same additives as sample 1 but also urea and formaldehyde monomers, as well as the same quantity of sodium chloride and has therefore a gel time of 28 seconds.
The particleboards obtained under the same con-ditions using a Bison line for both samples of the present example, gave a rate of production of 9 seconds per mm in case of sample 1 and 7 seconds per mm in case Gf sample 2.
The mechanical properties obtained according to DI~ 52360 to 52365 were equ.ivalent in both cases.

Table No. 3 , .
Samples Urea formaldehyde resin .-(65 % solids content) 140 lL,o Water 58 43.42 Ammonium chloride (20 % solution in water) 12 12 ~ Hexamethylenetetramine 8 8 :: Sodium chloride (100 %) 12 12 Urea (100 %) - 9.63 Formaldehyde (100 %) - 4.95 . .. ...
Total 230.00 230.00 Gel time in seconds 80 28 ~ Presstime in seconds per mm : thickness of nonsanded particle-~ 20: board 9 : : : : ~ ' -.
:: : :
::: : Properties Sam le P
1` 2 Density, kg/m3 660 640 : Thickness in mm 16.05 16.20 . Modulus of elasticity I. 24500 23200 Tensile strength, kp/cm 6.0 5.2 ,~ :
Bending strength, kp/cm~ 235 240 Water absorption, percent at 24 hours immersion ~ 45 60 Swelling, percent increase 30 at 24 ho;~rs:immersion 13.4 14 9 ,.

5~

Examp~e ll The present example illustrates the increased substitution of urea formaldehyde resin obtained by adding the catalyst according to the present invention as compar-ed to the smaller substitution obtained by using only so-dium chloride without the addition of urea and formaldehyde '' monomers, while obtaining particleboards in both cases having equivalent mechanical properties.
This example illustrates in particular that the substitution in the case of sodium chloride to resin is l:l while in the case of the mixture of sodium chloride with urea and formaldehyde theresin substitution is l~2.
A furnish of wood chips after pulverization . .
was~treated with the corresponding compositions given '~ 15 in table 4.
Composition l is considered'to be a blank with-out resin substitution.
The compositions differ in that in composition 2 .
we have a substitution of resin solids only with sodium ' ' ~ 20 chloride while in the third composition (composition ac-cording to the present lnvention) we~have,a substitution '' o.f resin by the mixture of~sodium chloride with urea form-aldehyde monomers.
In composition 2, 19.5 parts of solid resin are substituted by 19.5 parts of solid sodium chloride.
In composition 3, 39 parts of solid resin are substltuted by 19.5 par~ts of solid reactive catalyst (i.e.
sodium chloride, urea and formaldehyde).

- ~3 -... . . . . . . . . .... ., ... " , . .. ..... ,,.. ,, .,, ., ,,,,, , .,,, ",, ,,, .,, ~,,,, , ,, , .,, ,,~ , .. . ...... . .

85~
We havc- ~`/;.til coml~os.iti.oril 7, th~r~Iore ~ ~ubsr~i-tution of ~ rhi]e ~ith Con~jositio!l 3 a ~ul~;ti.tution of 1:2 is obtained.
The particleboard produced with both formu].a-tions have equivalent mechani.cal properties even though composition 3 has a lower solids content.
In both cases the particleboards are produced according to the 3ison system i.e. with continuous layer formation under controlled conditions which are kept con-stant for both cases presented.
Moisture of mat before the press 10.5.+ 0.5 %
Press temperature 210 C
; Pressure 35 kg/cm The quallty of the partlcleooard~produced is 15~ ~ ~reported in~the~followLng table 4.

:

: ~ ' ' ..
,; ,' . ~ ~ :; '', Tab]e No. 4 Components in parts by we;.ght Samples A B A B A B
Urea formaldehyde resin 100 200 90 180 80 160 Solids of urea formaldehyde resin 65 130 58,5117.00 52 104.0 Ammonium chloride (20 % solution) - 8.0 - 8.o - 8.o Water 68.5 31 72.0 38.0 66.].7 26.33 Ammonia 25 BAUMÉ 1.5 1.0 1.5 . 1.0 1.5 1.0 Sodium chloride 100 % - ~ 6.5 13,0 " " A ~ B - 19.5 (l)Reactive catalyst 100 % solids - - - ~ 6.5 13.0 .:
~eactive catalyst I00.%
solids A ~ B ~ 19.5 Water - - - - 15.83 31.67 : .
Total resins solution 170.00~240.00 170.00 240.00 170.00 240.00 Total solids content 65 131.665.o 131.6 58.50 118.60 % solids content 38.2 54.838.2 54.8 34.4 49.4 Parts~of resin solids - ~ 6.5 13.0 13.0 26.0 substituted Parts of resin solids A
substitutivn A -~ B - 19.5 : 39.0 .
% resin substit,uted A -~ B - 10 20 Ratio of added so:lid substi-tuent to resin solids substi-tuted - 1:1 1:2 ' ' . :

' 5~

Properties Sample Density, kg/m3 645 630 625 Thickness in mm 16.1 16.5 16.2 Modulus of elasticity L 24500 25000 23800 Tensile strength, kp/cm L~ .5 500 4.8 Bending strength, kp/cm 235 223 240 Water absorption, percent at 24 hours immersion 45 50 53 Swelling, percent increase at 24 hours immersion 14 17 16 (1). Components of reactive catalyst Urea 19 Formaldehyde 100 % 10 Sodlum chloride 100 % 71 Total 100 " .

Example 5 The novelty of our present invention is further llustrated by the ract that ~hen high levels of substi-: tutlon are desired it ;.s absolutely necessary ~o use the 20~ formulation according to our invention in order to spray the furnlsh in one st~ep as is practlseù~in all types of .. .
: : systems us~ed for particleboard production.
If only sodium chloride is adùed to the resin without the addition of urea and formaldehyde monomers, .
apart from the fact that speed is slow as already shown i i.n previous examples, a separate spraying of the wood chips with~sodium chloride i.s also necessary, with subse-..

" ' ' ' . .~ :

quent drying of the wood mixture and further spraying with adhesive Th;s means extra machinery, which is costly, and lower production The extra steps are necessary because of the low solubility of sodium chloride in water and also because in ; this case substitution of the resin is obtained by adding an amount in sollds content equal to the solids of resin substituted. In order to substitute high levels of resin, too much water is necessary in the formulation which can-not be dried in one step in the press within normal press times.
The formulation according to our present inven-tion may very well be used to substitute high levels of resin without usine too much water and allowing the pro-duction in one step, as is normally done for particle-board production, without any changes at all in the pro-duction steps.
This is poss1ble in our case because on the one hand we have a higher solubility in water and therefore less water, but also because the substitution is obtained by addlng only half the quantity of substituted material, calculated as solid matter~
As a matter of fact, in order to obtain the same -level of high subst~itution (35 ~ in the present example) using the reactive catalyst according to the present in-vention, we have a shorter gel time and therefore higher speed of production (formulation 3). In the case of using .

only sodium chloride without the addition of urea and formaldehyde monomers, we have a much higher gel time, the added substituents acting in this case as retarders instead of catalysts (formulation 2). All these mentioned points are proved in the formulations presented in tab-le 5~
In this table we present three formulations.
Formulation l is considered as a blank whereby - res~n is used without any substituents. Formulation 2 contains only sodium chloride to substitute resin and formul~tion 3 contains~the reactive catalyst according to the present invention i.e. a mixture of sodium chloride and urea formaldehyde monomers.;The percentaee of subst:Ltut-ed res1n; lS 35 % ln both formu].ations:~2 and 3~
15 ~ :In formulatlon 3, 37~.5 parts~of reactive cata-lyst are;ad~ded to substltute 6~8.5:parts of solid resin, while in~formulation 2,;:68~5~parts of sodium chloride are add~ed to obtain t:he same amount of substit~uted resin i.e. ~ :
68.5~parts~of resin.
20~ ::This proves~the point c~laimed that a substitu~
ti~Jn~of~1:1.8 is~obtalned while~by using only sodium chlo-rlde:~thére ls~:~a~substit~ution of~
The total~res1n~ solution~ o f`formulation 3 which~
contain~s the reactive~catalys~t according to the~present 25: .~ ~;inventi~on is~ke:pt the~same~as:in:~formu1atlon l~
Thls was not~pos~sib:Le in~the case~of~formulation~
: 2, whereby only s:odium chloride:is added because of the high amount o~f water~necessary 1n the~formulation~due to -:' ;

, .. . . . : :
. .

the high resin substitution.
The gel time of the blank is 60 seconds. In formulation 3 containing the reactive catalyst we have a lower gel time of 40 seconds which permits f'aster pro-duction ratesj in formulation 2, where only sodium chloride is used~ gel time is llO seconds~ the components added acting as retardants instead of as catalysts.
Column A in all 3 cases refers to the solution used to spray fine wood dust which is used in turn to form the external surfaces of the particleboard, while column B in all 3 cases refers to the solution used to spray wood flakes which are used to form the core of the particleboard.
Particleboards are produced using the~ resin , ~ : :
15~ ~formulations~as described in the three cases in table 5.
The production method;used~was the Bison system and the conditions~w~ere kept constant for all three cases pre~
sented.
Mo1sture;of mat before;the press: lO.5 + 0~5 ZO~ Press temperature - ~: 210 C
Press~ure~ 35 kg/cm The~quality~of the particleboard produced cor~
responded to the~standards~DIN 52.~360 to 52.365 and didnot~p~resent any~diff`erences~1n~c~ases 1~ and 3

2:5 ~ In case 2,~containing only the;sod1um~chloride~
ins~ead of the reactive catalyst according to the~present invention, the properties of~t~he; part1c1eboard obta~ned ~ -could not be measured because the boards obtained were 19 - :
, ' ~ ~ ' ; ' ~ ' ' ., ~ :

, ' B

already expanded under normal press times.
The proves that sodium chloride used by itself cannot give such high substitutions of the order o~ ~5 %
when used to produce particleboard with one spraying step according to the method well known in the art.

: , , ~: : : : ' ' ~:: ~ . : : :: :: :
: ~ :

::

: : :
: :; : ' ~ . ,:
~ , .
' .,.
:, . ~

',: , ~ ' , ... , .. , .: '.:,, ... : .... : . ' . , ': , Table N0 5 A B A B A B
Urea formaldehyde resin 100 200 65 130 65 130 Solids of resin65 130 42 84. 5 42 84. 5 Ammonium chloride (20 % solution) - 8 - 8 _ 8 Water 68.5 31 - - 68.5 31 .
Ammonia 25 BAUM~ 1.5 1.0 1.5 1.0 1.5 1.0 ~.
Sodium chloride (100 lo) - 23 45~ 5 - -Sodium chloride A+B - . 68.5 (l)Reactive cata-lyst (100 %)~ 12.5 25 Reactive cata-~: lyst A~-B - - 37.5 ~ater - _ _ 82 161.5 ~22.5 45 . ..
. ~
~ ~ To~a1 resin sol~lon 170 240 213.5 346.0 170.0 240 :
~Total s~ids content 65 131.6 65 131.6 54.5 111.1 % solids content38.~2 54.8 30.5 38 54 53 Parts of solid re-sin substituted ~ 23 ~ 45 ~.5 23 45 - 5 ~Parts of solid re- ; ~ ~
sin substituted A-~B :~ 68.5 68.5 % resin substituted A-~B ~ 35 ~ 35 :
Ratio Or added solid substituent to resin : ~
solids substituted ~ 1.8 Gel time in seconds ~ 60 110 ~ 40 (1). Components of reactive catalyst %
Urea ~100 %) 3 Formaldehyde (calculated as 100% solids) 15 5~dium chloride (100%) 55 Example 6 The present example illustrates the synergic behaviour obtained when a mixture of sodium chloride is added together with the non resinous condensation product of urea and formaldehyde monomers to the resin formulation.
The results are reported ;n table 6 where sample 1 contains only sodium chloride, apart from the usual additives added to the resin formulation for particle-board production, and has a gel time of 49 seconds. Sample ~ 10 2 contains a urea-formaldehyde condensate and has a gel ; ~ time of 51 seconds$ and samples 3 and 4 both contain sodium chloride and a urea-formaldehyde condensate, the :
sum of whic'n equals the amount of sodium chloride used n sample l, all calculàted as 100 % solids. Both sample~s

3 and 4 have a gel time lower than samp~les 1 and~2 and ln particu~ar, both samples 3 and 4 have a gel time of 42 seconds.

, :
, :, - : :
, . .

, .

Table No 6 Urea formaldehyde resin (65 % sol;ds content) 140 140 140 140 Ammonium chloride (20 % solution in water) 8 8 8 8 Ammonia 25 BAUMÉ 2 ^2 2 2 Sodium chloride (100 %) 12 _ 8.55 5-5 Urea (100 %) - 1.73 1~73 3.16 Formurea(l) (80 % solution in water) - 2.15 2.15 4.18 Water _ 4 72.12 63.57 63.16 Total 226 226 226 226 Gel time in seconds at lO~C 49 51 42 42 (1) Formurea is a low condensate of the following composition:
55 parts by weight formaldehyde 25 parts by weight urea 20 parts by weight water.
.

Example 7 :
The present example illustrates the synergic behaviour obtained when a mixture of potassium chloride is added together with the condensation product of urea and forrnaldehyde rnonomers to the resin formulation.
The results are reported in table 7, whereby sample 1 is the blank with water instead of the catalyst according to the present invention. Sample 2 contains potassium chloride and sample 3 contains a mixture of ~1~985~
potassium chloride together with a condensa'ce of urea and formaldehyde monomers.
Sample 1 has a gel time of 93 seconds, sample 2 shows a slight cata].ytic effect with a gel time of 82 seconds but sample 3, which contains the reactive catalyst according to the present invention, shows a surprisingly high catalytic effect with a gel time of 42 seconds.

- Table No,7 Urea formaldehyde resin (65 % solids content) 140 140 140 Ammonium chloride ; (20 % solution in water) ~8 8 8 Ammonia 25 BAUM~ 3 3 3 Potassium chloride (100 %) - 12 12 Urea (100 %3 - - 7.38 : , :
Formurea(l) (80 %~solution in water) - ~ 9 Water ~ 75~ 63 46.62 ; Total ~ 226 226 2?6 Gel time in seconds at 100 C ~93 g2 42 (1) Formurea is a low condensate of the foll~owing composition:
:: : ~ : :: : ~
55~parts by weight formaldehyde~
:
25 part,s by weight urea 20 parts by weight water.

. 24 ~

Examp:l.e 8 The present example refers to production of veneered particleboard. It illustrates more precisely the fact that the catalyst according to the present invention may be used also for glueing together flat sheets such as for the production of plywood, blockboard, veneered boards or other multilayer boards. In this case, a sheet of veneer of the Tianna type, having 0.6 mm thickness and a moisture content of 10 %, is glued onto both faces of a sanded particleboard having 15 mm. thickness, size ; 183 x 305 cm. and moisture content of 9 %.
The glue is spread on to the particleboard by means of a glue spreading machine.
The boards are pressed with a pressure of 7 kp/cm2 and at a temperature of 120 C.
Two samples are presented. Sample 1 uses the :
normal glue formulation while sample 2 uses a formulation according to the present invention. The formulations are :
~ shown in table 8.;
;
~ 20 ~ ~While the boards produced~with the formulation , according to sample l need a pressing t~ime of 2 minutes, ;~ boards produced with the formulation according to sample 2 . .
need a.pressing time of 1.7 minutes.
The glue formulation using the catal~st according to the present invention for the production of veneered particleboard has therefore the following advantages:
; Increase in speed of~production of 15 %.
Glue saving of 26 %.

Table Mo 8 Urea formaldehyde resin (65 % solids content) 100 70 Ammonium chloride (20 % solution in water) 8 8 Sodium chloride - 6.oo Urea (100 %) - 1.62 Formaldehyde (100 %) - 0.83 Water - 21.55 .0 Flour 7 10 Total 115 118 Example 9 The present example illustrates the synergic :~ :
behaviour obtained when a mix~ure of sodium chloride is added together with urea and formaldehyde monomers to a resin formulation based on melamine-formaldehyde resin.
The resin used is Kauramin 542 of BASF.
:
~ The~results are report-ed in table 9. Sample l ~ ~
, ~ , . , : ~
is a blank. Sample 2 contains, apart from the usual for-~
~mulation of resin, ammonium chloride and ammonia, also ~
sodium chlor1de. Sample~3 contains, apart from the usual formulation of resin, ammonium chloride and ammonia, also urea and formaldehyde.
All these samples have the same gel time, i.e.
65 seconds.
~ ~ Sample 4 contains, apart from the usual formu-lation of resin, ammonium chloride and ammoniag also ureag formald~h~de and sodium chloride, the total surn of the mixture added being ec~ual to the amount of the single compvnents added in samples 2 and 3.
Sample 4 represents, therefore, an example of the catalyst according to the present invention and it actually has a much lower gel time, i.e. 43 seconds.

Table No.9 Melamin-formaldehyde resin (65 % solids content) 140 140 140 140 Ammonium chloride t20 % solution in water) 8 8 8 8 Ammonia 25~ BAUMÉ 2 2 2 2 Sodium chloride (100 %) - 12 - 12 Urea (100 %) - ~ 3.2 3.2 Formaldehyde (100 %) - - ~1.651.65 Water 76 ~4 71.1559.15 .: , . .
otal 226226 226 226 Gel time in seconds at 100 C ~ 65 65 65 48 Similar results may be obtained, if in the pre-ceding examples the sodium or potassium chloride is re-placed by lithlum chloride or the fluorides, bromides or lodides of sodium, potassium or lithium.

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Claims (15)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A material for bonding together water-penetrable cellu-losic particles which comprises: an amino resin, and 1 to 30% by weight of a catalyst system, calculated as 100% solids and based on the weight of the amino resin, to effect polycondensation of the amino resin, said catalyst system compris-ing an aqueous solution of an organic component and an inorganic component wherein the organic component is formaldehyde and urea or a nonresinous condensation product of formaldehyde and urea and the inorganic component is a water-soluble alkali metal halide.

2. The material defined in claim 1 wherein the amino resin is urea-formaldehyde.

3. The material defined in claim 1 wherein the amino resin is melamine-formaldehyde.

4. The material defined in claim 1 wherein the alkali metal halide is sodium chloride.

5. The material defined in claim 1 wherein the ratio of the organic component to the inorganic component of the catalyst sys-tem is 0.1 to 1.5 parts by weight of the organic component to 1.0 part by weight of the inorganic component, and wherein the amount of water in said catalyst system is dependent upon the solubility of the organic and the inorganic components.

6. The material defined in claim 1 wherein the catalyst system further comprises a surface active agent in an amount of 0.1 to 2% by weight of the catalyst system.

7. The material defined in claim 1 wherein 8 to 12 parts of ammonium chloride by weight are added per 70 to 160 parts by weight of a solution of the amino resin.

8. In a method of bonding water penetrable liynocellulosic particles with a catalytically polycondensed amino resin, the improvement which comprises curing the amino resin at a tempera-ture higher than room temperature and sufficient to effect curing in the presence of 1 to 30% by weight of an additional catalyst system, based on the weight of the amino resin and calculated on the basis of 100% solids content, comprising an aqueous solution of a mixture of organic and inorganic components, the organic component being formaldehyde and urea or a nonresinous condensa-tion product of formaldehyde and urea, and the inorganic compon-ent being a water soluble alkali metal halide.

9. The improvement defined in claim 8, wherein the addition-al catalyst system contains the organic and inorganic component in a ratio of 0.1 to 1.5 parts by weight of organic components per 1.0 part by weight of inorganic component, the amount of water depending upon the solubility of the organic and inorganic compon-ents and the solids content required for the production system used.

10. The improvement defined in claim 8, wherein the organic component of the catalyst system is formaldehyde and urea and the inorganic component of the catalyst system is sodium chloride.

11. The improvement defined in claim 8, wherein the catalyst system is added to the amino resin, together with a catalytically effective amount of ammonium chloride so that the production rates are increased by up to 30 percent while simultaneously allowing up to 30 percent by weight less resin solids to be used without imparting any loss in bonding strength.

12. The improvement defined in claim 8, wherein the bonded lignocellulosic particles form particle board.

13. The improvement defined in claim 8, wherein the bonded lignocellulosic particles form plywood.

14. The improvement defined in claim 8, wherein the bonded lignocellulosic particles form blockboard.

15. The improvement defined in claim 8, wherein the bonded water penetrable lignocellulosic particles are free from formal-dehyde odor.