Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
ll`~J33g2
The present invention relates to thermosetting etherified methylol-
aminotriazines which are substantially free from electrolyte and contain,
as a statistical average, 1.3 to (2n) methylol groups per mol of the amino-
triazine (n being the number of amino groups in the aminotriazine and
usually amounting to 2 or 3) which are etherified to the extent of at least
33% with a glycol derivative of the general formula I:
R-(ocH2cH2)moH (I)
wherein R denotes an aIkyl group having 1 to 4 C atoms and m represents
an integer from 1 to 4, and which are suitable, with particular advantage,
for the manufacture of mouldings, laminates and surface coatings.
It is hlown to manufacture mouldings by pressing combinations
of thermosetting aminoplast resins, carrier materials and optionally
further additives, such as pigments, flow auxiliaries and slip agents or
release agents, at an elevated temperature. Carrier materials which are
suitable for this purpose are, in principle, substantially all absorbent
inorganic or organic structures. The carrier materials are impregnated with
the aminoplast resins in a known manner, for example by application with
brushes or rollers, spraying-on or dipping, and dried to the required
residual moisture content. The sheet-like combinations thus obtained are
laid one on top of another in several layers and are pressed to form mould-
ings at elevated temperatures.
The sheet-like combinations of carrier material with aminoplast
resins are also suitable for the surface coating of other materials, such
as, for example, wood or chipboard. Thus they are used in the furniture
industry, for example, for coating sheets of chipboard, hardboard or ply-
wood or other wood-based materials. In this application the carrier
-- 1 --
3 1~t33~Z
materi~ls, aft~r impregnation -~ith aminoplast resin, are
pres~ed onto the wood-based ~aterials under the action o~
heat and pressure usi~g a gluing agent.
furtner known method of manufacturing mouldings by pres-
Qing comprises combining aminoplast re~ins with pulverulent
~illers and optionally further known additives, such a~
pigments,~low au~iliaries and o~tionPlly slip agents or
relea e agents, and pressing the~e products in mould~ at -
elevated temperature.
The properties o~ a moulding ~anufactured by one of the
above-mentioned process are de~endent to a large e~tent on
the naturs o~ the aminoplast resi~ used. The Pm;noplast
res;n~ hitherto known have disadvantages which in some
cases considerably limit their applicability for the pur-
poses n~icated above. ~hus, for e~ample, the sheets
which coul~ be manufactured by Impregnating paper webs or
te~tile web~ with the melamine resins hitherto known T~ere
insuf~iciently ela~tic for m2~y end uses. Admittedly it
wa~ known ~hat the elasticity and hence the bendi~g radiuQ
can be improved if modi~ying agents, such as, for e~ample,
glycols, are added to the aminoplast resin. ~he improve-
ment in elasticity produced i~ ~his way was, howe~er,
associated with a deterioration of the resistance to wæte~,
so th~t the sheets could not be u~ed for some end use~,
~or e~ample en~a~ing profiled mouldings. The laminates or
wood-based mouldings manufactured by pressing or by impre~-
~tir.g p per webs or textile webs or wood veneers with
known ainoplast resins also did not exhibit adequate
elastieity, above all in cases ~here the ~anu~actured
mouldings are to be employed in situations in which they are
subjected to an ~lternating e~osure to heat.
~ 1~i`3392
In the construction of electrical apparatus also, the
mouldings manufactured with aminoplast resins hitherto
known did not exhibit, because of their electrolyte con-
tent, the desired properties, such as high electricalresistance and high tracking resistance.
Etheriiied methylolaminotriazines hitherto known have
been manufactured by methylolation and simultaneous or sub-
sequent etherification oi the methylolaminotriazines in
the presence o~ acid catalysts (compare Houben-Weyl,
volume 14/2, pages 35~-368; Ullmann Enzyklopadie der
technischen Chemie (Ullmann's Encyclopaedia oi Industrial
Chemistry), volume 3, pages 487-489). The degree o~
methylolation here, ior example in the case of melamine,
is generally 3-6. Aiter the completion oi the reaction,
it was necessary to neutralise the acid catalyst employed
and to remove the resulting salt by iilteration. This was,
however, generally only incompletely acco0plished, so that
on storing the products manui'actured in this way an un-
desirable turbidity was produced which was due to further
precipitation oi the salt and, moreover, the residues of
salt which could not be removed let to an extremely sharp
decrease in the electrical resistance and the tracking
resistance of the mouldi~gs manu~actured with aminoplast
resins of this ~ind.
Previously known methylolaminotriazines etheri~ied with
long-chain alcohols have hitherto been obtained mainly by
trans-etheri~icatio~ oi corresponding methyl ethers under
conditions oi acid catalysis.
It has now been iound, surprisingly, that thermosetting
etheri~ied methylolaminotriazines which are substantially
~i - 3 _
11(3;~39Z
free from electrolyte and contain as a statistical average
1.3 to 2 n methylol groups per mol of the aminotriazine
(n being the number of amino groups in the aminotriazine)
which are etherified to the extent oi at least 33Z with a
glycol derivative o~ the general formula I
R-(CH2CH2)mOH (I)
wherein R denotes an alkyl group having 1-4 C atoms and m
represents an integer ~rom 1 to 4, do not display the dis-
advantages of the thermosetting aminoplast resins known
hitherto and are there~ore suitable, with particular advan-
tage, ior the manufacture of laminates and wood-based
mouldings o~ high elasticity and high resistance to water
and also electro-technical laminates and compression
mould~ngs o~ high tracking resistance.
Examples o~ glycols, oi the general ~ormula I, which can
be used ~or the manu~acture o~ the etheriiied methylolamino-
triazines to be used ln accordance with the invention, are
methylglycol, ethylglycol, diglycol monomethyl ether, digly-
col monoethyl ether, digl~col monopropyl ether, triglycol
monomethyl ether, triglycol monoethyl ether, triglycol mono-
propyl ether, triglycol monobutyl ether, tetraglycol mono-
methyl ether, tetraglycol monoethyl ether, tetraglycol
monopropyl ether and tetraglycol monobutyl ether. Examples
o~ aminotriazines which can be used for the manuiacture oi
the etheriiied methylolami~otriazines to be employed in
accordance with the invention are melamineS benzoguanami~e
and acetoguanamine.
It is preierable to employ those methylaminotriazines
which contain as a statistical average 1.8-2 n methylol
groups per mol oi the aminotriazine, and especially those
which contain 1.8 to 1.2 n methylol groups per mol of the
A
115~339Z
aminotriazine. Those methylolaminotriazines in which at
least 50~ of the methylol groups are etherified, are also
preferred. Amongst the glycols of the general formula I,
employed for the etherification, those glycols are preferred
in which R denotes a methyl group, and in addition, those in
which m represents the number 1 or 2. Glycols of the general
~ormula I which are particularly pre~erred are those in
which R denotes a methyl group and m represents the number
1 or 2. A further group of preferred methylolaminotriazines
to be used in accordance with the invention are those which
are derived ~rom melamine.
It was surprisingly iound that the use of glycol derivatives
oi the general formula I
R_(OCH2CH2)mOH (I)
~or the etheri~ication of the methylolaminotriazines ren-
ders the use o~ acid catalysts super~luous and that the
molar ratio oi aminotriazine to formaldehyde can be varied
within considerably wider limits than has hitherto been
known in the case o~ normal etheriiied melamine-iormaldehyde
condensation products.
Owing to the absence o$ acid catalysts, neu*ralisation of
the reaction mixtures is not necessary, so that completely
electrolyte-iree products may be obtained.
The freedom ~rom electrolyte is a decisive ~actor in the
outstanding electrical properties of the mouldings accord-
ing to the invention and the wide range o~ degree of
methylolation permits the properties o~ the products accor-
ding to the invention to be adjusted even to extreme
industrial demands, with special reference to elasticity,
resista~ce to water and resistance to heat and changes of
temperature.
-- 5 --
116~;~3~z
The etherified methylolaminotriazines to be employed in
accordance with the invention are manufactured by condens-
ing an aminotriazine with formaldehyde and with an excess
of the glycol derivative of the formula I, 1.3 to 2 n mols of
formaldehyde - if n is the number of amino groups in the
aminotriazine - being employed per mol of the aminotriazine
and the condensation reaction being carried out in the
absence of acids and alkalis. The condensation reaction
usually takes place at temperatures of 50 to 180C, pre-
ferably 80 to 140C. The condensation reaction is con-
tinued until the degree of etherification of the reaction
product is at least 33 %. The excess of glycol to be
employed can be 1.2 to 20 times the theoretical amount.
After the desired degree of condensation has been achieved,
the excess of glycol remaining is removed conveniently by
distillation, preferably in vacuo. The water of reaction
iormed during the condensation reaction is preferably dis-
tilled off continuously. The removal of the water of
reaction by distillation is also appropriately carried out
in vacuo.
Ii the water of reaction is removed continuously by dis-
tillation during the reaction, it is possible to determine,
from the quantity of the latter, the degree of etherifi-
cation of the reaction product which has been achleved.
The formaldehyde ls preferably employed in the form of
paraformaldehyde. It is, however, also possible to use
aqueous solutions of formaldehyde or solutions of formalde-
hyde in the glycol derivatives of the general formula I
which are employed in accordance with the invention for the
etherification.
_ _
392
The manufacture of mouldings by using the etherified
methylolaminotriazines according to the invention is
carried out by combining the etherified methylolaminotria-
zine with a carrier or filler and pressing the resulting
compositions under pressure at elevated temperature so as
the produce mouldings.
The compositions can be obtained by impregnating, for
example, absorbent sheet-like materials, such as, textile
webs composed of natural or synthetic ~ibres, especially
cellulose fibres; random fibre fleeces, in particular
absorbent paper; and wood veneers, with the aminoplast
resins of the present invention. The impregnation can be
carried out in a known manner, for example by application
with brushes or rollers, spraying-on or dipping, the general
procedure being such that the impregnated materials contain
25 to 75 %, pre~erably 25 to 50 %, and most pre~erably 30 to
40 % of the aminoplast resin. After impregnation, the
materials are dried to a residual moisture content of 1 to
11 %. The sheet-like combinations thus obtained are laid
one on top o~ another in several layers and are pressed to
form mouldings, conveniently at temperatures between 110
and 170~ and pressures between 2.0 and 800 kp/cm2.
A ~urther known posstbility ~or manufacturing mouldings by
pressing consis~s in combining aminoplast resins wlth
pulverulent fillers and optionally further known additives,
such as pigments, flow au~iliaries and optionally slip
agents or release agents, and pressing these products in
moulds at elevated temperature. Known fillers which may be
used in compression moulding compositions comprising a
pulverulent ~iller and an aminoplast resin of the present
invention are, ~or example~ wood ~lour, cellulose powder
~ 1~339Z
including cellulose ester powder, cotton flock, flour, starch,
peat, waste products from the wood industry, ground miner-
als, asbestos fibres or graphite, of which the first two
mentioned are preferred. Pigments which may be used the
compositions of the present invention can be organic or
inorganic, Suitable inorganic pigments are generally based
on sulphides, oxides or mixed oxides of metals, especially
of titanium, zinc, iron, chromium, cobalt, lead and cadmium.
Carbon black is a preferred black p~gment. Possible organic
pigments are the compounds characterised in the Colour
Index as pigment dyes.
Known flow auxiliaries which may be used include sorbitol,
glycols and glycol derivatives and polyglycols.
Metal stearates, preferably zinc stearate and magnesium
stearate, may additionally be employed as slip agents or
release agents, which are required for trouble-free release
of the moulding from the compression mould.
The aminoplast resins are mixed with the filler and option-
ally the further additives in known manner, for example,
in kneaders or drum mixers and this process can be carried
out at elevated temperatures from 70 to 140C preferably
from 105 to 120C. In relation to the energy required for
kneading and the homogeneity of the combination which can
be achieved, kneading at elevated temperature gives sub-
stantial advantages. After mixing, the resulting combination
is cooled to room temperature and generally solidifies. The
solid product may be granulated and can then be pressed.
Pressing is generally carried out at temperatures between
120 and 180C, preferably 140 and 170C, under pressures
of 200 to 800 ~p/cm2, preferably 400 to 600 kp/cm2. The
pressing time is usually from 10 to 60 minutes for the
manufacture of moulded laminates and 30 seconds to 5 minutes
~,
,,~
11~)3392
for the manufacture of mouldings using pulverulent ~illers
(further described hereinbelow). Compression moulding
compositions obtained by using pulverulent fillers can
contain 40 to 70 %, preferably 50 to 60 %, of the aminoplast
resin.
Surface coatings using the compositions of the present
invention are generally manufactured in such a way that, as
in the manufacture of moulded laminates, a sheet-like
carrier material is first impregnated with the aminoplast
resin o~ the present invention as described above and the
resin content of the composition can be ~rom 25 to 45,
pre~erably ~rom 30 to 40 %, relative to the weight of the
total combination. As described above, ~he impregnated
carrier materials are subsequently dried to a residual
moisture of from 3 to 10 %. The sheet-like resin-carrier
combinations thus obtained are pressed onto the sur~aces
to be coated, using an adhesion promoter, under a pressure
of from 2 to 12 kp/cm2, pre~erably from 4 to 6 kp/cm2, and
at temperatures from 110 to 170, preferably from 140 to
150C. The pressing time is generally ~rom 30 seconds to
4 minutes, preferably irom 1 to 2 minutes.
Ii desired decorative surface coatings may be manufactured
in this way by using a suitable printed or dyed decorative
paper as the sheet-like resin carrier material. Curved
sur~aces, such as, for example, profiled mouldings, can
also be coated in a trouble-free manner with the combina-
tion to be used in accordance with the invention, owing
to its extremely high elasticity. It is also possible, for
example, to coat chipboard sheets all round, by drawing the
sheet-like combination according to the invention round the
edges. This was not possible using coating agents, based
~1
39z
on aminoplasts, which were previously known. It was
necessary here to coat the individual plane surfaces
separately.
If desired it is also possible, in the case of the sheet-
like compositions used to manufacture mouldings, to print
the web-like carrier materials in a decorative manner with
organic pigments before the impregnation or, if sheet-like
carrier materials containing cellulose fibres or textile
fibres are involved, to dye or to print the carriers with
textile dyestuffs.
In order to manufacture the mouldings of the present inven-
tion ~rom the sheet-like compositions, several layers are
pressed to produce the moulded laminates at temperatures
from 110 to 170C, preferably 130 to 150C, and at a
pressure of from 2.0 to 800 kp/cm2, preferably 50 to 120
kp/cm2, and most preferably 80 to 100 kp/cm2.
The moulded laminates manufactured using the aminoplast
resins according to the present invention are distinguished
by an outstanding elasticity and, at the same time, very
good resistance to water. Owing to their extremely high
res~stance values and their high tracking resistance, they
are outstanding suitable for the manufacture of components
in the electrical industry. The same valuable properties
are also displayed by mouldings which have been manufactured
using the aminoplast resins ~ccording to the invention in
combination with pulverulent fillers. Further advantages
of the mouldings and surface coatings which can be manu-
factured in accordance with the invention are their resis-
tance to high and low temperatures and to changes in
temperature, and their excellent Martens heat distortion
point, high impact strength and flexural strength and low
after-shrinkage.
-- 10 --
~; ~.
~,
~i~3392
Example 1
5,300 ml of methylglycol, 1,372 g of melamine and 650 g
of p-formaldehyde are stirred at 120C. A clear solution
has formed after 1 1/2 hours. Approximately, 1.5 of methyl-
glycol are distilled off. This gives a melamine resin
solution which contains 66% of condensation product
(determined by the loss of weight oi a sample when heated
at 120C for 1 hour), can be diluted with water to an un-
limited extent and can be diluted with n-butanol to a
limited extent, that is to say 1 part of the resin under
consideration can be diluted with 1 part of n-butanol at
20C without becoming turbid. The analysis of the product
shows that 15.4~ consist oi bound iormaldehyde and 21.3~
as bound methylglycol. The proportion of solvent is 33.8% ,
determined as methylglycol.
Exam~le 2
1,260 g oi melami~e, 450 g of p-formaldehyde and 6 1 oi
methylglycol are stirred ior 1 1/2 hours at a bath temperature
of 140C. A solution is formed. 1.5 1 of methylglycol are
now distilled off. A resin which can be diluted with water
in a ratio oi 1 : 2.0 (that is to say 1 ml of resin takes
up 2 ml of water at 20C without becoming turbid) and can
be diluted with n-butanol in a ratio oi 1 : 0.8 ls obtained.
The resin can be diluted with methylglycol to an unlimited
e~tent. The resin contains 53~ o~ condensation product (1
hour at 55QC/20 mm Hg) and the viscosity, measured in a DIN
beaker with a 4 mm nozzle, is 18.5 seconds.
Exam~le 3
126 g of melamine, 40 g o~ p-formaldehyde and 500 ml of
methylglycol are stirred for 2 hours at a bath temperature
-- 11 --
11~'3~332
of 140C; a clear solution is formed. About 200 ml of
methylglycol are now distilled off. A 62~ strength resin
(the strength is determined as above), which contains 11,2%
oi formaldehyde and 18~ of methylglycol in a bound ~orm is
obtained.
Exam~le 4
126 g of melamine, 90 g of p-formaldehyde and 1.2 l of
ethylene glycol monobutyl ether are stirred at 140C in
an apparatus with a descending condenser until no further
water distils oif.
After distilling oi~ 600 ml of ethylene glycol monobutyl
ether in vacuo, a 60~ strength resin which can be diluted
with n-butanol to an unlimited extent is obtained.
ExQm~le 5
187 g of benzoguanamine, 120 g oi p-formaldehyde and 1 l of
methylglycol are heated to 120C for 20 minutes; a clear
solution is formed. 600 ml o~ methylglycol and water are
now distilled of~. 540 g of a 62% strength resin which has
unlimited miscibility with n-butanol, can be diluted with
4 parts of xylene and can be diluted with water in a ratio
of 1 : 2 is obtained. The viscosity is 17 seconds ( 4 mm
DIN beaker).
126 g o~ melamine, 180 g of p-~ormaldehyde and 1.2 l o~
methylglycol are boiled under reflux for 1 hour and 800 g
of methylglycol and water are then distilled of~ slowly.
730 g oi an 80% strength resin are o~tained, which can be
diluted with water and n-butanol to an unlimited extent.
- 12 -
1~339Z
~ampl~ 7
t,00~ g o~ ~la~ine, 800 g o~ p-formaldehyde and 8 1 of
methyl~lycol are boile~ unde~ reflu~ ~or ~ hour3 and
appro~i~ately 6 1 of methylglycol and watar are then dis-
ti1led off.
3 k~ of a 91~o strangth re~in are obt~i~ed, which is mis-
cible -~ith water in all proportions.
~ le 8
7 1 of diglycol monomethyl ether, 630 g o~ melamine and
48Q æ of p-for~aldehyde are heated to120-130C under a
~acuum o~ 400-500 mm ~g, whilst stirring. In the course
thereof, 600 ml of water of reaction are removed by dis-
tillation.
The e~ce~3 diglycol monomethyl ether (appro~imately 4 l)
is no~ distilled off at 100C bath temperature under a
~acuum o~ 10 mm Hg. This recover~d diglycol monomethyl
ethe- can be used again in I~rther batches.
2.1 '~g o~ 75~0 strength resin (the strength is determined
by the content of frëe ~on-etheri~ied methylglycol since,
becæuse of the high boiling point of thi~ alcohol, deter-
mination of the ~olids by the customary method do2s not
give reproducible results), ~rhich is miscible ~th water
in all proportions are obtained. It can be diluted in t~e
~01107n~g ratios with the lo110l~ling solvents:
~oluene 1:10
n-Eutanol 1:3
Iiethanol 1:
If ~et~yl~ri~lycol or ethyltriglycol is used in place o~
methyl~i~lycol and the procedure is other-,rise as described
in ~ ~ple 8, essentially s~silar results are ob~ined.
1~
il6~33~z
With these very high-boiling glycol derivatives it is
advisable to carry out the concentrating operation under
1 mm ~g using a thin iilm evaporator.
The examples which iollow illustrate some of the possi-
bilities for use oi the aminoplast resins according to
the invention.
Example 9
10 sheets of an electrolyte-iree paper weighing 80 g/m2
are impregnated in the aminoplast resin manufactured
according to Example 1. Aiter drying, which is carried
out at 130C, the res~n content is about 60% and the
residual moisture content (determined by drying a sample
at 160 C ior 5 minutes~ is about 6~.
rhe papers are laid one on top oi another and are pre~sed
~ a multi-daylight press between nickel sheets chromium-
plated to a high gloss, ior a period oi 15 minutes at a
temperature o~ 140C and under a pressure of 80 kp/cm2.
Aiter cooling the lami~ate under pressure to approxi~ately
70C, a laminate 1.1 mm thick is obtsined. Testing this
laminate gives the $ollowing data:
Curing stage in Kiton test: 2 - 3
Electrical suriace resistance DIN 53,482 : 5.5 x 10125~L
Tracking resistance DIN 53,480: stage KA 3b.
Exam~le 10
A paper printed with a wood gra~n pattern and weighing 80
g/m is impregnated in a solution, diluted with water to
40~ by weight oi solid resin, oi the aminoplast resin manu-
factured according to Example 7. The resin content oi the
impregnated paper is approximately 38~ and the residual
- 14 -
110339Z
moisture content is approximately 2%.
The impregnated paper is glued cold onto a chipboard sheet,
using a commercially available polyvinyl acetate glue~ A
length oi the paper corresponding to the thickness oi the
board is allowed to project beyond the edges o~ the chip-
board and the latter are encased in a second process by
bending the paper round the edge, using a suitable white
glue. The paper is so elastic that no cracks are iormed
during the encasing. The encased chipboard sheet can then
be provided with a coating o~ an acid-curing lacquer.
Example 11
70 parts oi the resin manufactured according to Example
6, 30 parts o~ microcellulose, 4 parts oi titanium dioxide
and 1 part o~ zlnc stearate are rolled out into a milled
hide on a roll mill at 110C. Aiter the molled hide has
been granulated, a moulding is produced in a standard bar
mould at 150 - 155C and 250 kp/cm2 with a compression t~me
oi 10 minutes (or 8 minutes ior testing aiter-shrinkage);
it has the iollowing properties:
Fle~ural strength according to DIN 52,362: 840 Xp/cm2
Tracking resistance according to DIN 53,480: KA3c
Martens heat distortion point (~IN 53,~62): 121C
After-shrinkage according to DIN 53,464: 1%
Impact strength according to DIN 53,453: 7 kpcm/cm2.
Exam~le 12
The method o~ preparing resin as described in Example 7
was repeated a~d yielded 2.1 kg oi 70~ strength resin, the
strength o~ which was determined by the value obtained on
- 15 -
392
stoving for 1 hour at 120C, and which was miscible with
water in all proportions. It could be diluted in the
following ratios with the following solvents:
Toluene 1:40
n-Butanol 1:3
Methanol 1: ~o
The resulting product was diluted with isopropyl alcohol
to a concentration of approximately 45X. 2% oi p-toluene-
sulphonic acid (relatlve to solid resin) was added in order
to ~ccelarate curing.
A cellulose carrier web weighing approximately 250 g/m2
is impregnated in this solution to a resin content of
approximately 25~, relative to the ~inal weight of paper, and
is dried at 130C to a residual moisture content oi 1%.
The curing oi the resin in the sheet takes place at the same
time as the drying. The melamine resin sheet is then given
a lacquer coating, approximately 30 g/m~, of an acid-curing,
commercially available lacquer, and is glued, as a highly
elastic overlapping edge band, onto the edge oi a chipboard
~heet using a commercially available hot-melt adhesive based
on ethylene-vinyl acetate copolymers.
E~am~le 13
The method of preparing resin as described in example 7 was
repeated and approximately 2.1 kg of a 70~ streDgth resin
which was miscible with water in all proportions, obtained.
The resin solution is then diluted with water to S0~ strength
and pieces of wood veneer, 0.8 mm thic~, are impregnated
i~ it to a resin content of approximately 28-32~, and are
dried in a circulating air oven to a residual moisture con-
116);~392
tent of 7-8%. 10 layers of this wood veneer are pressed
to give a sheet between nickel sheets chromium-plated to
a high gloss, at 140C, under a pressure of 110 kg/cm2
and ~or a period o~ 18 minutes. The floowing values are
determined on the sheet.
Flexural strength according to DIN 52,362: 2,237 kp/cm2
Impact strength according to DIN 53,453: 21.2 kpcm/cm2
Water pick-up aiter storing ~or 96 hours at 60& 11.7~.
No cracks are formed on subjecting the sheet to an alterna-
ting heat treatment o~ 3 periods o~ 20 hours at 80C, and
cooling to 20C three times.
