CA1101575A

CA1101575A - Amino-resin compositions

Info

Publication number: CA1101575A
Application number: CA281,518A
Authority: CA
Inventors: Donald A. Hubbard; Richard G.C. Henbest
Original assignee: Imperial Chemical Industries Ltd
Current assignee: Imperial Chemical Industries Ltd
Priority date: 1976-06-28
Filing date: 1977-06-28
Publication date: 1981-05-19
Also published as: SE7707388L; AU506619B2; IT1081275B; FR2356696A1; DE2728803A1; GB1532888A; FR2356696B1; NO771970L; NL7706345A; AU2593877A; JPS533445A; NZ184337A

Abstract

Canadian Abstract The present invention provides a composition comprising an unreacted j or partially-reacted mixture of formose and at least one amino resin, in particular ???? formaldehyde, containing ?% to 50% by weight of formose solids and 5?% to 95% by weight of amino resin, the molar ratio of formaldehyde to amino groups in the amino resin component being from 0.6 : 1 to 1.5 : 1, and the composition being in the form of an aqueous solution having a solids content of 40% to ?0%
by weight.

Description

~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 , '.~

' IL57~

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.

' 5i 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 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 , f~

;7~i 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 ,~ .

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

Claims

The embodiments of the invention in which an exclusive property and privilege is claimed are defined as follows:

1. An aqueous amino-resin composition having a solids content of 40 to 80% by weight comprising an unreacted or partially reacted blend of formose and at least one amino-formaldehyde resin having a molar ratio of formaldehyde to amino groups within the range 0.6:1 to 1.5:1 said blend containing 5 - 50%
by weight of formose solids and 95 - 50% by weight of amino-formaldehyde resin solids, based on the total solids in said blend.

2. An aqueous amino-resin composition as claimed in claim 1, containing 10 to 30% of formose solids and 70 to 90% of amino resin, by weight of the total solids.

3. An aqueous amino-resin composition as claimed in claim 1, wherein the molar ratio of formaldehyde to amino groups in the amino-resin component(s) is within the range 0.7:1 to 1:1.

4. A process comprising the step of reacting an aqueous solution of formaldehyde or paraformaldehyde under alkaline conditions to produce a formose solution, and the step of blending or partially reacting the said formose solution with (a) an amino-formaldehyde resin solution and/or (b) a mixture of additional aqueous solution of formaldehyde or paraformaldehyde and at least one amino compound capable of forming an amino resin with formaldehyde.

to form an aqueous composition having a solids con-tent of 40 to 80% by weight and containing an unreacted or partially reacted blend of formose and at least one amino-formaldehyde resin having a molar ratio of formaldehyde to amino groups within the range 0,6:1 to 1.5:1, said blend containing 5 - 50%
by weight of formose solids and 95 - 50% by weight of amino-formaldehyde resin solids, based on the total solids in said blend,

5. A process as claimed in claim 4, wherein the formose solution is neutralised prior to the blending or partial-reacting step,

6. A process as claimed in claim 4, wherein the said formose solution is blended or partially-reacted with the additional aqueous solution of formaldehyde or paraformaldehyde and the compound capable of forming an amino-resin formaldehyde, and/or with such an amino-resin, under acidic conditions,

7. A process as claimed in claim 4, wherein the resulting composition containing formose and an amino-resin is substantially neutralised by the addition of an alkaline substance and concentrated by evaporation.