Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
~3L5~7~
The present invention relates to amino-resin
co..;positions containing urea ,ormaldeh-yde, mel~mirle c;~alda-
hyde, phenol-formaldehyde and/or mixtures thereof. The
compositions possess characteristic features which render
them advantageous to use in a number of applications.
In accordance with the present invention, there is
provided an amino-resin composition comprising an unreacted
or partially-reacted mixture of at least one amino~resin
and formose, An unreacted mixture is simply a blend of
the amino-resin(s) and formose, whereas a partially- .
reacted mixture additionally contains some additional
amino-resin which has been formed as a result of
reaction between the amino-resin(s) and formose during
the preparation of the mixture, ;
The amino-resin compositions of the present : :
invention preferably comprise:-
5 - 50% (by weight of the total solids) of formose
solids
50 - 95% (by weight of the total solids) of amino- .-
resin solids ,:
The compositions will normally be in the form of . ~.
aqueous solutions having solids content ~0 - 80%
by weight~ :
More preferably the compositions compri.se~
10 - 30% of formose solids by weight of the total
solids, -.
70 - 90% of amino-resin solids by weight of the total
solids,
The molar ratio o~ formaldehyde to amino-groups in
the amino-resin components are preferably within the
range 0.6 : 1 to 1.5 : 1, more preferably between
2 ,
'.~
'
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0,7 : 1 to 1 : 1. (For example, for a urea-
formaldehyde c~ndensate, the molar ratios of
formaldehyde: urea are from 1,2 : 1 to 3 : 1,
preferably 1 4 : 1 to 2 : 1), The formaldehyde in
the amino-resin component does not, o course, include
that already reacted to form the formose,
The amino-resin compositions of the invention may be produced
by reacting or blending an amino-resin with a solution of
formose. The formose solution may be produced, for example,
by heating formalin with a base, particularly Ca(OH)2; this
reaction is self-catalytic, and can be speeded up in the
initial stages by the addition of a small quantity of
previously-formed formose or a saccharide such as sucrose,
glucose or dextrose. It can also be prepared by the
treatment of paraformaldehyde wlth dilute alkali.
Formose is a complex mixture of hexoses, pentoses
and other carbohydrates, It is racemic and not readily~
fermentable by yeasts. It is normally obtained in aqueous
solution, and can be concentrated to a syrup.
The~amino-resin component can be prepared, for
example, by the aqueous condensation of formaldehyde with
ure~ and/or melamine. Production of an amino-resin usually
involves the steps:-
(a) Mixing urea and/or melamine and formalin,
and reacting (usually with heating) at a pH of
about 7,0.
(b) Condensation of the mi~ture by heating at a
pH of about 4 - 6 during or ater which
further additions of urea and/or melamine
can be made.
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Formose solution or syrup can be added at any s~age;
it is particularly convenient, however, to add it at the
beginning, before step (a), so that reaction can occur
between formose and the other components, and so that the
bulld~up of the characteristics o~ the amino-resin
composition can be monitored as the reaction proceeds.
PROPER~IES, AD~ANTAGES AND USES
A variety of amino-resin compositions with various
properties can be produced. More particularly, amino-resin
compositions of either high solubility in water or low
solubility in water can be produced ?
Highly-Soluble amino-resin compositions are produced
with relatively high formose contents (e g. at 15% by
weight or above) and/ox with higher formaldehyde: amino
group ratios (e.g. above about 0 75 : 1~ Limiting the
degree of condensation of the amino-resin also favours
solubility in water
Amino-resin compositions of low solubility are -
favoured by lower formose contents, lower formaldehyde :
urea ratios and higher degrees o~ condensation~
Water-miscible amino-resin compositions show a lack
of syneresis on gelation and curing, and in particular
are resistant to cracking when cured and dried as castings
or coatings They are of use in the manufacture of foams,
e g ~or cavity wall insulation, as surface coatings,
especially when used with fillers such as sand, gypsum
or clay, and as modifiers and coatings for plaster
products Because of their waterlmiscibility, they are
also useable as paper, board and textile additives, for
example to achieve an improved wet strength in paper and
board products
LS~,5
A feature of these amino-resin compositions is that
in the presence of fire, the cured amino resin composition
undergoes intumescence, i e the formation of an expanded,
charred mass which can insulate other material from the
effects of the fire. Use in intumescent coatings is
therefore indicated
The less soluble amino-resin compositions do show
syneresis on gelation and curing, and are less resistant
to cracking on curing. However, they can be modified to
prevent this, for example by the addition of latex and/or
sodium silicate, or they can be used as adheslves for
wood products such as particle board In either case,
the useful property of intumescence on burning is
maintalned~ ~ ~
The amino-resin compositions can be cured by the
addition of an acid and/or by heating (preferably below
100C) if necessary The amino-resin compositions tend
to cure more slowly than conventional resins, and ~o the
use of 5 trong acids is recommended.
EXAMPLES
1. Preparation of Formose Solution
1440 ml of formalin (36% HCMO, 5 6% methanol),
456 ml of water, 82g of Ca(OH)z and 4g of dextrose, were
gently heated in a flask fitted with a reflux condenser.
At a temperature of 55C heating was stopped, and an
exotherm taking the mixture rapiclly to 94C occurred
The formose solution so obtained was cooled, neutralised
with 340 ml of 25% w/v Na2CO3 solution, and filtered.
The filtrate was concentrated by evaporation under vacuum
at 37 - ~0C to give a formose solution of approximately
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37% concentration, Analysis showed a Ca conten-t of 1250
ppm and a free formaldehyde content of 0,735% w/v,
2, A premix of urea and formalin, having a formalde-
hyde : urea r~-tio of 2 : 1, was prepared from 432
mls of formalin (36,4%) and 171,5g of urea, 250 ml
of formose solution from Example 1 was added, and
the pH adjusted to 7,0 by adding NaOH solution,
The mixture was refluxed for 30 minutes, and then
the pH was reduced to 5,0 by adding formic acid
solution. The mixture was refluxèd for 145
minutes. Then the pH was raised to 5.8 ~NaOH
solution was used), cooled, and further NaOH
solution was added to bring the pH to 7,8. The ;~
mixture was concentrated by vacuum evaporation at ,~
40C, to give a resin composition with the following
characteristics~
- Solids content 68% ' -:
Specific gravity 1,255 :~
Water tolerance (at 25C) 3000% :~
Formose content 22% based on solids ~ -
Viscosity 1,8 poises
A portion of the resin composition was gelled by ~ '
adding 10% of 30% phosphoric acid solution; it gelled in
:. .
45 minutes without syneresis, and on long-term drying and
curing gave a rigid material without cracking. . ~.
On burning, the material showed intumescence. .
3, As in Example 2, except th~t ~23 ml formalin)
3molar ratio ':
193 g urea )1.75
were used, The acid condensation stage was performed at
pH 5,0 for 66 1/2 minutes. The resin composition
properties were: -
~1 ,
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Solids content 72%Specific gravity 1~281
Vi5cosi~y 5,3 poises
Water tolerance 500%
Forrnose content 22%
A sample was gelled as in ~2), givin~ gelation in 40
minutes with no syneresis and no long-term crackin~.
4, As in Example 2, except that 423 ml formalin)
)molar ratio
220,5g urea )1.55 : 1
were used, The acid condensation was done at pH 5.0 for
46 minutes.
The resin composition properties were:
Solids content 70%
Specific gravity 1.281
Viscosity 3.6 poises
Water tolerance 180%
Formose contant 22%
Samples, gelled as before, showed syneresis, and a tendency
to crack upon ageing at 50C, The material showed
pronounced intumescence on burning.
5. A ~ormose solution was prepared as described in
Example 1, and concentrated to 40% formose. 250
parts of this solution were added to a mixture of
460 parts of formalin (36.5% formaldehyde, 6.5%
methanol) and 193 parts of urea (molar ratio of
formaldehyde : urea 1.75 : 1, farmose content 20%).
The mixture was refluxed for 15 minutes, adjusted
to pH 4.85 (by the addition of formic acid solution),
and further refluxed for 68 minutes. The solution
was adjusted to pH 5.5 (by the addition of ~aOH
solution), cooled to 40C, and further adjusted
,~ .
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to pH 7.5 The resin was concentrated by vacuum
evaporation at 42-48C to give a resin of viscosity
11 poise.
6 Part of the resin produced in Example 5 was
concentrated by further vacuum evaporation to
35 poise viscosity, and blended with an equal
amount of a conventional UF resin of similar
viscosity to give a resin containing 10% formose.
The resin used for blending was prepared by a
conventional process (namely by neutral reaction
followed by acid condensation, then evaporation)
. ~.
and had a formaldehyde : urea ratio of 1.95 : 1 ~
,
7~ A formose solution was prepared as dascribed in
Example 1, and concentrated~to 50% formose.
300 parts o this solution were added to a mixture
of 220 5 parts of urea and 460 parts of~formalin
(as used in Example 5) The~mixture~was~adjusted
: ~- :
to pH 7, refluxed for lS minutes, and then acidi~
fied to pH 4.85 (by the addl~tion of formlc acid
solution) and refluxed for a further 55 minutes.
The mixture was then part-neutralised, cooled,
and brought to pE 7.5 It Was then vacuum-
evaporated at 48 to 50C to give a resin of
viscosity 100 poise. The formose content of tha ~ -
resin was 30%, based on the total solids
