Note: Descriptions are shown in the official language in which they were submitted.
5t~
This invention relates to the use of salts of poly-
imide amines with organic or inorganic acids for the surface
sizing of paper and to surface sizing agents derived therefrom.
The polyimide amines are derived from copolymers of maleic acid
anhydride and 2, 4, 4-trimethyl-1-pentene.
It is known from D~S No. 1,570,914 ( Belgian Patent
No. 654,889) that maleic acid anhydride copolymers containing
unsaturated monomers such as, for example, styrene, vinyl
and allyl ethers, and unbranched ~ olefins as comonomers,
can be reacted with a diamine and optionally a monoamine.
The diamine contains both a primary and also a tertiary
amino group, and the reaction is carried out in inert organic
solvents. lhe polyimide amines obtained thereby are quaternized
with epihalohydrins, for example epichlorohydrin. These
quaternized p:roducts are used in aqueous solution as surface
sizing agents for paper. The polymers have molecular
weights of from 2000 to 5000. With higher molecular weights
gelation occurs and with products of very low molecualr weight
~below 2000), the sizing effect is inadequate.
It is known from German Patent No. 1,5959704 that
maleic acid anhydride homopolymers or copolymers can be
reacted with a mixture of diamines containing a primary and
a tertiary amino group and primary monoamines. In this case,
there is approxlma~tely one primary amino group for each
anhydride group, and the reaction is carried out at elevated
~ 1119758
temperature in aqueous or alcoholic-aqueous acids. From 25
to 350 mole % of acid equivalents are used, based on
tertiary amino groups in the amine mixture. The polyimide
amines thus produced are suitable in neutral form as
emulsifiers and dispersants for the production of coatings
and protective coatings. They are also suitable for use
as hydrophobing agents and as intermediate products for
plant protection agents and pharmaceuticals.
For the production of paper sizing agents, polyimide
amines of ~he type known either have to be mixed with non-
cationic polymers ~German Patent No. 1,621,68B) or converted -
into graft polymers with special olefinically unsaturated
graft monomers ~German Patent No. 1,621,689). As can be
seen from the comparison tests in German Patent No.
1,621,688, the polyimide amines when used on their own -
.~ ..
have a distinctly weaker, and inadequate sizing effect.
It has now surprisingly been found that polyimide
amines of the above-mentioned type, which are derived from
copolymers of maleic acid anhydride and 2,4,4-trimethyl-1-
~' 20 pentene by reaction with a mixture of diamine containing a
`~ tertiary and primary amino group and a primary monoamine,
may be used directly in the form of an aqueous solution of
their organic or inorganic acid salts as extremely effective
- surface sizing agents for paper.
Accordingly, the present invention provides the use
of salts of organic or inorganic acids with polyimide amines
derived from copolymers of maleic acid anhydride and 2,4,4-
.'' ~:
~i
.,
. ~ 3
~ . . .
'75~3
trimet}lyl-l-pentene by reaction with a mi~ture of a diamine contain-
ing a tertiary and a primary amino group and a;nmonia Ol a primary
monoamine as surface sizing agents for paper and paper-like materials.
The present invention likewise provides a process for sizing paper
wherein the afore-mcntioned salts are used as sizing agents.
The copolymers of maleic acid anhydride with 2,4,4-
trimethyl-l-pentene preferably have an equimolar, alternating
structure. Their average molecular weights are between
8000 and 500,000 and preferably between 10,000 and 60,000,
as determined by membrane osmometry. The preferred copolymers
have intrinsic viscosities of from 0.08 to 0.3 dl/g, as
measured in N, N-dimethyl formamide at 25C.
Copolymers having intrinsic viscosities of less than
0.08 dl/g are far less effective sizing agents for paper.
Products of excessively high molecular weight lead to
excessive viscosities of the sizing agent and, hence,
to poorer processibility.
For producing the polyimide amines, the copolymers of
maleic acid anhydride and 2,4,4-trimethyl-1-pentene are
reacted in an anhydrous organic medium with a mixture of
A) a diamine containing a primary and a tertiary amino group
and
~) ammonia or a primary monoamine
at temp-eraturesof from 0 to 250C and at least 80% and
preferably more than 85% of the anhydride groups in the
copolymers are converted in-to the corresponding imide groups.
The molar ratio of diamine (A) to monoamine (B) is
between 1: 0.~ and 1: 2Ø
-- 4 --
~. r
. . . ~
The diamines used have the general formula (~)
(A)
N-R-NH2
R2
and the monoamines used have the general formula ~B)
~B) R3-NH2.
e formulae, R is a C2 - C12, preferably
C2 ~ C6, linear or branched aliphatic chain which may optionally
contain oxygen or sulphur atoms. The substituents Rl and R2
of the tertiary amino group may be the same or different and
each represents an aromatic radical, such as phenyl, tolyl,
xylyl, chlorophenyl, nitrophenyl, and 4-dimethylaminophenyl,
but preferably phenyl, tolyl, and xylyl, an araliphatic
radical, such as benzyl, and 2-phenylethyl, but preferably
benzyl, an alkyl radical having from 1 to 12 and preferably
from 1 to 6 carbon atoms, or the two substituents Rl and R2
together may form a 5-membered or 6-membered cyclic ring
optionally containing an oxygen or sulphur atom.
Preferred diamines are those in which the primary and
tertiary amino group are separated from each other by a
linear alkylene chain having from 2 to 6 me~hylene groups and
of which the tertiary amino group is substituted by linear
Cl-C4-alkyl radicals. l~Amino-3-dimethylaminopropane is
particularly preferred. It is however, also possible to use
. mixtures of the afore-mentioned diamines.
1119758
The substituent R3 is a saturated or unsaturated
aliphatic or cycloaliphatic optionally substituted hydro-
carbon radical.
Preferred monoamines are ammonia, aliphatic primary
monoamines having from 1 to 18 carbon atoms, cycloaliphatic
monoamines having from 5 to 8 carbon atoms or mixtures thereof.
Particularly preferred monoamines are, for example, methyl-
amine, ethylamine, n-propylamine~ n ^butylamine, sec.-butyl-
amine, iso-butylamine, tert.-bu~ylamine, n-hexylamine,
2-ethylhexylamine, cyclohexylamine and dehydroabietylamine.
A particularly preferred amine mixture consists of
l-amino-3-dimethylaminopropane and ethylamine in a molar
ratio of from 1:1 to 1:1.6.
The mixture of the diamines (A) and the monoamines (B)
is used in a substantially equimolar quantity, but preferably
in a small excess, based on the anhydride groups in the
starting polymer. The amine mixture used should preferably
contain from l.0 to 1.5 moles of primary amino groups per
mole of anhydride groups in the polymer. The amine excess
is added to obtain as complete an imidation as possible and
this should amount to at least 80% and preferably to more
than 85%. Reaction products having a lower degree of imidation
are difficult to dissolve in water and generally show an
inadequate sizing effect on paper. In the mixture of diamine
(A) and primary amine (B), the molar ratio of diamine to
monoamine should amount to between 1:0.3 and 1:2Ø The two
amine components may be reacted either in admixture or
successively. Suitable solvents are inter alia organic alkyl-
"~ - 6 -
1119758
and halogen-substituted aromatic solvents, such as benzene,
toluene, m, o- or p-xylene or mixtures thereof. They are
capable of dissolving both the maleic acid anhydride-2,4,4-
trimethyl-l-pentene copolymers and also their reaction products,
that is, the polyimide amines.
To produce the sizing agents and to dissolve the
polyimide amines in aqueous systems, the polyimide amines
have to be converted into salt form. Inorganic or organic
acids are suitable for this purpose, and are added in quantities
of from 100 to 500 mole %, based on the tertiary amino groups
present in the chemically bound amine mixture. Suitable acids
are, in particular, formic acid, acetic acid, propionic acid,
lactic acid, hydrochloric acid, nitric acid and sulphuric
acid, but preferalby formic acid or acetic acid. Water is -
generally used as solvent. On completion of the reaction, ~ ~
the polyimide amine salts are normally present in the form of ~`
a 5 to 30% solution. The products show no signs of the
gelation described in Belgian Patent Specification No. 654,889
in the relatively high molecular weight range above 5000.
Imidation of the copolymer of maleic acid anhydride
and 2,4,4-trimethyl-1-pentene is preferably carried out in two
steps. In the first step, the copolymer is suspended or
dissolved in the organic solvent at temperatures of from 0C -~
to 50C and the amine mixture is added dropwise with stirring
-:
at the same temperatures. This step of the reaction results
predominantly in the formation of the monoamide. In the second
step of the reaction, the reaction mixture is heated with
stirring to a temperature of from 130 to 200C. This step, in
which imide formation takes place from at least 80 % and
-- 7 --
- : , :-: ~. . : . , .- .
- . . , - .. . :
`~ 111~758
~` preferably from more than 85 % of the original anhydride
groups, is carried out thermally, optionally in the presence
of catalysts, such as for example p-taluene sulph~nic acid~ or
pyridine, with elimination of water.
The organic polymer solution may be converted into an
aqueous polymer solution by for example continuously
introducing said organic solution in a heated receiver
containing dilute aqueous acid with simultaneous removal of
the organic solvent by distillation.
In contrast to the teaching of German Patent Specification
No. 1,595,704, the copolymers of maleic acid anhydride and
2,4,4-trimethyl-1-pentene reacted to form polyimide amine
salts are used in the present invention as surface sizing
agents for paper having excellent sizing effect in aqueous
solution alone, i.e. without any need for additives. In
contrast to hydrophobing agents, which have a water-repelling
effect, sizing agents are products which enable paper to be
written on with ink without the ink runni~g. Whereas therefore
hydrophobising agents are water-repellent and insoluble in
water, the sizing agents of the present invention are soluble
in water.
In addition, it has been found that the process described
in German Patent Specifications Nos. 1,595,704 and 1,621,688
for producing polyimide amines is not suitable for the sizing
agents used in the present invention, because said process
gives products which do not even remotely approach th~ required
high degree of imidation of at least 80 %. Thus, salts of these
products with acids are also unsuitable for use as sizing agents
for paper.
~1197S8
One advance over German Patent Specification No.
1,621,688. in which cationic sizing agents are used in the
form of dispersions, is the fact that, in the present invention,
the sizing agents are used in homogeneous aqueous solution.
They can be processed without difficulty, guarantee absolute
homogeneity of the sized paper in contrast to the hetero- ~
geneous sizing systems, and show an outstanding sizing -
effect on papers of all kinds, the sizing of chalk-containing
paper being particularly effective. The sizing agents used
in the presentinvention are clearly superior in this respect
to all conventional sizing agents. -
The parts quoted in the following illustrative Examples
represent parts by weight unless otherwise stated. --
EXAMPLE A
In a three-necked flask equipped with a water separator, ;
105 parts of an alternating copolymer of maleic acid anhydride
and 2,4,4-trimethyl-1-pentene ~average molecular weight
GPC 47,000) is introduced into 260 parts of xylene. The
copolymer is dissolved with stirring at 120C, followed
by the successive dropwlse addition of 26 parts of dehydro-
abietylamine dlssolved in 174 parts of xylene and 63 parts of
l-amino-3-dimethylaminopropane. The mixture is then left to
react for 10 hours at 150 to 160C while using the water separator. ~
The quantity of water separated off during the azeotropic ;
distillation with xylene is regarded as an approximate measure -
1) MGPC = molecular weight as determined by gel permeation
chromatography
:.. ,, . ,, ,. ,- . :
,.: .. , , : :: . ., , ,- . . . .
~119758
of the conversion (8.5 ml = 94~ conversion). On completion
of polyimide formation, 50 parts of formic acid are added
dropwise. Most of the xylene is decanted off from the
precipitating polyimide amine salt, the rest of the solvent
being azeotropically distilled off with steam. At the same
time, an aqueous solution with a solids content oi 9.1
by weight is obtained.
EXAMPLE B
105 parts of copolymer of maleic acid anhydride and
2,4,4-trimethyl-1-pentene (MGpC= 47,000) is dissolved in
260 parts of xylene at 120C. A mixture of 45 parts of
stearylamine and 34 parts of 1-amino-3-dimethylaminopropane
dissolved in 174 parts of xylene is added dropwise with
stirring to the polymer solution. A product insoluble in
xylene, probably the monoamide, is initially obtained during
the highly exothermic reaction, being converted into the
soluble polyimide amine with elimination of water by stirrlng
for 10 hours at 150 to 160C ~ile usin~ the water separator.
Formation of the polyimide amine can be recognized very
easily from the IR-double band characteristic oi cyclic
five-ring imides at 1690 cm 1 and 1770 cm 1, whilst the
partial band characteristic of cyclic five-ring anhydrides
at 1840 cm 1 disappears. 34.5 parts of iormic acid are then
added dropwise. The organic solvent is distilled oi~ with
steam at 100C. The aqueous solution has a solids content
of 14.9 ~ by weight.
.
Le A 18 058 - 10 -
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: , . . ::
1119758
EXAMPLE C
The procedure is as in Example B, except that, instead
of the amine mixture used in Example B, a mixture of 46 parts
of dodecylamine and 26 parts of 1-amino-3-dimethylamino-
propane dissolved in 174 parts of xylene is added dropwise.
The aqueous solution has a solids content of 10.5 % by weight.
EXAMPLE D
The procedure is as in Example B except that, instead
of the amine mixture used in Example B, a solvent-free
mixture of 15 parts of hexylamine and 39 parts of l-amino-
3-dimethylaminopropane is added dropwise. The aqueous
solution has a solids content of 13.5 % by weight.
EXAMPLE E
105 parts of copolymer of maleic acid anhydride
and 2,4,4-trinethyl-1-pentene is dissolved in 435 parts of -
xylene at 120C, followed by dropwise addition of a mixture
of 22 parts of cyclohexylamine and 28 parts of l-amino-
3-dimethylaminopropane. 8.3 parts of water are separated off
in the water separator ~= 92 % conversion). Thereafter 35
parts of formic acid are added, followed by distillation with
steam at 100C. The aqueous solution has a solids content of
7.9 %.
EXAMPLE F
525 parts of the same copolymer as in Example A, 200
parts of xylene, 91 parts of n-butylamine and 128 parts of
l-amino-3-dimethylaminopropane are introduced into a stirrer-
equipped fine steel autoclave. After heating with stirring
to 50C, the mixture is kept at that temperature for 2 hours
- 11
. . , . , - - .
11~9758
and is then stirred for 3 hours at 130C. 42.5 parts of
water are separated off in the water separator (= 94~
conversion). 250 parts of formic acid are then added to the
solution and the xylene is azeotropically distilled off with
steam. The aqueous solution has a solids content oi 11.4 ~.
EXAMPLE G
525 parts of the same copolymer as in Example A,
dissolved in 525 parts of toluene, is introduced into a
stirrer-equipped autoclave toget~er with 1650 parts of
xylene, 85 parts o~ 1-amino-3-dimethylaminopropane and 98
parts of n-propylamine, followed by stirring for 3 hours at
50C and then for 7 hours at 130C. 40 parts of water are
separated off in the water separator (= 890h conversion).
173 parts of formic acid are added dropwise to the so~ution
of the polyimide amine, followed as before by distillation
with steam. The aqueous solution has a solids content of
6.5 oh~
EXAMPLE H
The procedure is as in Example G except that, instead
of n-propylamine and 1-amino-3-dimethylaminopropane, a mixture
of 126 parts of ethylamine and 112 parts of 1-amino-3-di-
methylaminopropane is used. The aqueous solution has a
solids content of 9.6 oh~
EXAMPLE I
814 parts of the same copolymer as in Example A is
introduced into a stirrer-equippea autoclave together with
3100 p~s of xylene, 181 oarts of 1-amino-3-dimethylaminopropane
and 112 parts of ethylamine. The mixture is then stirred ~or
Le A 18 058 - 12 -
. ~ , . . .
. ~
~119758
3 hours at 50C and for 7 hours at 130C. 65 parts of water
are separated in the water separator ~= 93% conversion).
380 parts of formic acid are added dropwise to the solution
of the polyimide amine, followed by distillation with steam.
The aqueous solution has a solids content of 10.8% and a -
viscosity at 25C of approximately 30 cP, as measured in a
Haake Viscotester.
The use of sizing agents A - H is described by way of
example in the following:
The sizing solution used for surface sizing consisted of -
a solution of 5% by weight of starch (Perfectamyl A 4692,
a product of the AVEBE company) and 0.25% by weight or,
in some cases, 0.5% by weight of the sizing agent to be ~~
tested (expressed as active substance) in 94.75% by weight
or 94.5% by weight of water.
A laboratory sizing press of the type manufactured
by the Werner Mathis company of Zurich (type HF) was
used for sizing. The sizing solution had a temperature of
approximately 20~C in the sizing press. The paper was
drawn through the sizing press at a rate of 4 metres per
minute.
The surface-sized papers were dried in 45 seconds at
about 100C on a drying cylinder. Before the sizing test,
the papers were conditioned for 2 hours at ambient temperature.
Pieces of the paper were then preweighed, immersed for 1 `
minute in water at 20C, squeezed oncebetween filter paper
under the weight of a 10 kg roll and then reweighed. The
value for the absorption of water on both sides was calculated
.~
-''i''7~
~J
- 13 - -
-
. ~ . ,-, :, ~ - .
~19758
in g/m2 from the difference ln weight The lower the water
absorption, the better the effect o~ the tested sizing
agent. A good sizing eXfect i9 shown by a water absorption
of about 40 g/m2 or less.
EXAMPLE 1
This Example is intended to demonstrate that good
sizing effects can be obtained with the described sizing
agents on unsized papers o~ bleached pulps.
The raw paper used had been produced ~rom bleached
sulphite pulp with the addition o~ 3 ~ of China Clay (expressed
as ash) at pH 6.8 and had a weight per unit area Or 70 g/m2.
: Table 1:
Surface sizing on unsized paper of bleached ~ulp
Water absorption in g/m2 with addition of
Sizing agent 0.25 ~ by weight 0.5 ~ by weight
of sizing~agent (based on pure active
substance) to the
sizing solution:
: ~ A 38.0
B 56.8 38.1
~: C 57.7 40.0
; D 43.9
E 44.2
F 39.9
G 37 9
H - 35 3
In the absence of sizing agent, water absorption is
: 87 g/m .
EXAMPLE 2
This Example demonstrates the ei~ectiveness o~ the
described sizing agents on papers containing mechanical wood
pulp. The raw paper used had been produced from 50 ~
bleached mechanical wood pulp and 50 ~ bleached sulphite
Le A 18 058 _ 14 _
1119'7~i~
p u l p W i t. ll t}~ e a d d i t, i O I~ O f I 1 ~lo () I ( ~ h ~ l y ( . ~ 1 ',
ash) A t p~l 5 and ha~l a we i gil t ~)cr ulli t al`cSl 1~1 7(; ~r;/m~~
Table 2~
__
Surface sizing on unsized paper eontai~ n" mechaJ~ic~:t wood
pulp
Si~ing agent Water absorption i.n g/m wi,th addition of
O . 25 /0 hy ~eight 0 . 5 /0 by weight
of sizing agent (based on pure ac ti-ve subs tance~
to the si~;ing solution:
3!~ 0
B 68 4 37. 6
C 55 . l 34 ~ 8
D 33.3
E 34.5
F 31.0
G 31~2
H 31.0
In the absence OI sizing agen-t, water absorption is
92 . 7 g/m
EXAMPLE 3
This Example demonstrates the favourable e~fec-t of
the described siz.ing agents on papers containing cal cium
carbonate ~
The raw paper used had been prod-uced from 51) /0
bl.eached pine sulphite and 50 /0 bleached beech sulphate
pulp with the addition of 14 /0 precipitated ca:l ci~n carbonate
( e2~pressed as ash) at lpH 6 . 8 and had a weight per unit area
of 70 g/m 0
Le A 18 058 - 15 -
~975B
Table 3:
Surface sizing on unsized paper containing calcium carbonate
Sizin~ agent Water absorption in g/m2 with addition of
025 ~ by weight 0.5 ~ by weight
of sizing agent (based on pure active
substance to the sizing solution:
A 37.0
B 53.4 31.8
C 54.5 44.5
D 32.8
E 35.7
F 32.6
G 33.5
H 34.6
In the absence of sizing agent, water absorption amounts
to 77.6 g/m .
EXAMPLE 4
In this Example, one of the described products, sizing
agent J, is compared with a cationic "sizing agent M"
which represents the prior art and which corresponds in
its composition to the products described in G~En Patent Nb.
1,621,688.
The following raw papers were used:
20 Raw paper I: as described in Example 1
" II: as described in Example 3
III: bleached pulp, approximately 12 ~ oi talcum ash,
1 ~ of aluminium sulphate, unsized; approx.
80 g/m
25: " IV: bleached pulp, approximately 7 ~ China Clay ash,
presized with 0.1 ~ o~ resin size and 0.5
oi aluminium sulphate; approx. 75 g/m2.
The degree of sizing against ink was determined by
means o~ a Hercules Sizing Tester in accordance with the
operating instructions of the~manuiacturers, Hercules Inc.,
Le A 18 058 - 16 -
'.' ' ~'. - , - - `.: ~`''. ' `; ' `.
. .
~9758
Wilmington, Delaware, USA. The test apparatus used measures
th0 period of time in seconds which is required for the
remission value to fall to 75% of the remission value of
paper when the test ink is applied to the paper and
penetrates through it. The longer the time measured, the
better the degree of sizing.
Table 4:
Comparison of one of the described products, sizing agent J,
with a standard commercial-grade sizing agent M on various
papers ~ -~
Paper: Sizing agent: Degree of sizing with addition of
0.125 0.175 0.25 % by weight
of active substance to the solution: -
.
I Comparison M79 177 352 secs.
Sizing agent J 144 344 401 secs.
II Comparison M19 69 152 secs.
Sizing agent 1 77 231 298 secs.
III Comparison M129 424 532 secs.
Sizing agent J 245 619 816 secs.
IV Comparison M42 130 304 secs.
Sizing agent J 194 237 414 secs.
It can clearly be seen that, in all the unsized and
presized papers tested, the sizing effect of sizing agent J
is considerably superior to that of the standard
commercial-grade sizing agent M in the three practical
concentrations selected.
EXAMPLE 5
This Example demonstrates the suitability of the
described sizing agents for use in pulp.
1 % and 2 % of sizing agent ~active substance, based
on dry pulp) were added with stirring to a pulp of 50 % of
birch sulphate, 30 % of pine sulphate and 20 % of spruce
- 17 -
.. . .
., - - ; . :~ -
- . : . -- , ~ .,
11197S8
sulphite pulp (pulp density 0.5 ~) at a pH-value of 6.9.
Sheets of paper were then immediately formed on a
laboratory sheet former and dried at 100C. The paper had
a weight per unit area of approximately 100 g/m2.
The sizing effect was determined by the "ink float test"
normally applied in the paper industry, i.e. by applying the
papers to test ink (Pelikan 4001).
A cationic "sizing agent M", corresponding to the
products described in German Patent No. 1,621,688, was
again used for comparison.
Table 5:
Comparison of the described sizing agents with a standard
commercial grade sizing agent M when used in pulp
Sizing agent: Ink float test: no penetration of ink through
paper pulp-sized with
1 ~ by weight 2 /0 by weight
Sizing agent M 10 mins after 20 mins.
" A 10 mins. 20 mins.
" B 10 mins. 20 mins.
C 1 min. 2 mins.
D 5 min~. 20 mins.
" E 10 mins. 20 mins.
" G 10 mins. 20 mins.
" H 10 mins. 20 mins.
Le A 18 05~ - 18 -
