Note: Descriptions are shown in the official language in which they were submitted.
~ -5-!: ~ 3 2 9 Q 7 2 300/1
D e s c r i p t i o n :
"
The invention concerns a process for producing paper
~ webs impregnated with synthetic resins in the form of solutions and dispers-
;: ions.
: ~ .
.
- It is known and customary to completely coat or en-
case the casinys for television and radio sets, hi-fi devices and other furni-
ture parts with plastic foil. PVC foils of varying thicknesses are preferably
used for this purpose.
These PVC foils are adhered, for example, to wood
chipboard, and furniture parts or casings are produced in a single work pro-
cess from these composite materials, in accordance with technical furniture
principles, that is to say, V-shaped grooves are cut into the ~ood chipboard,
(,
and the sheets are then folded or bent into these grooves, and thus casings,
furniture parts or the like are produced in a single work operation.
,:.
It is important in this process that no tearing of
., ,
the foil occur at the fold line. It is furthermore disadvantageous in this
process that the PVC foil MUSt be subjected, directly before its use and in
order to attain good printability, to a corresponding surface treatment, such
- ~ as, for example, a corona treatment
, .~
~, . Furthermore, the chipboards must have a very clean and
;~ results
s~ smooth surface so that economically justifiabletcan be attained (application
of thin foils).
\
,1
, . ,
,, .
,~':
;
,','~ ,
.~,,,:
;
1 32~072
It is, however, especially disadvantageous that the
PVC foil has a very unfavorable dimensional stability (expansion/contraction
performance) if temperature changes take place, or if there are low tensile
strengths, low light stability, or a high electrostatic chargeability, and if
a softening has already taken place at 75 to 85C. Upon heating to more than
120C, an HCl separation furthermore takes place.
.'!. .
It is thus the task of the present invention to pro-
^~duce a foil-shaped, resin-containing, web-shaped material which does not have
the disadvantages of the pure plastic foils generally used, and which further-
more has good flexibility and water resistance, and resistance against solvents,
,.:
as well as good internal strength and good dimensional stability under the
influence of moisture, and temperature changes.
~',,;
;~Furthermore, the tape-shaped material must be able to
be produced from favorable raw materials in an economical manner, and with as
few additional process stages as possible, with the exception of the production
of the smoothed paper web itself.
,
From the existing literature, for exam?le, from
D~-PS 25 50 980, it is known to impregnate backing paper webs with aqueous soak-ing solutions and/or dispersions through the absorption of the soaking fluid in
,~a suction zone, whereby a quantity at least sufficient for complete saturationis applied to the surface of the paper web, and the paper web is subsequently
conducted over an absorption zone, in which the impregnation fluid is sucked
. ..
. ~,
,
:
!
.,
;.,'
.
-;s
"~
.. . .
~ 8- 3~0/1
1 329072
through to the other side. Soaking resin solutions are, however, resins on the
base of urea, melamine, and phenol resins, and contain formaldehyde, and lead
to brittle products.
~` .
~ In this process it is necessary to conduct the backing
. paper web after.its production to a second device and to unroll it again,
,,
to impregnate it by using additional devices, such as an absorption zone and a
drying device, and to roll it up again.
Furthermore, in this process the distribution of the
impregnation fluid is uneven over the cross-section of the paper, so that zones
of greater impregnation arise next to zones of lesser impregnation, which can
lead to the splitting of the paper grain.
In DE-OS 3û 24 394, a process for producing a plastic
veneer in a paper machine is described, in which the paper web is provided in
'~ the dry part with an impregnation, wh;ch takes place in the adhesion press.
The saturation of the paper web with the impregnation fluid, not described here
in greater detail, in the press is, however, only complete, if the paper web
has already been pre-impregnated, so that even here additional devices are neces-
sary.
The most cQmplete possible saturation and impregnat-
~ ion of the backing paper is, in accordance with the invention, only possible if,
```1:
~ in addition to the s~lection of a suitable application or impregnation device,
~ the~properties of the paper, such as, for example, milling condition and degree
of milling, absorptive capacity of the fiber materials, pOrQSity and surface
~ .
~`,`' .
... .
.. '.'~ ~,. : .. . .
- ~ : : : : . :,
:
.. . .
~ 9 0 ~ 2 300/1
ra~ness, are adjusted to the properties of the impregnation or coating mixture,
that is to say, the surface tension~ viscosity, condition of electrical charg-
ing and solids content.
The problem is solved in accordance with the invent-
ion through the fact that the paper web is formed from a cellulose fiber mix-
ture of high absorptive capacity and strength, which is milled to a degree of
milling of, at the most, 35 SR, and the impregnation fluid consists of a mix-
ture of aqueous, anionic copolymer dispersions and aqueous, anionic polymer
solutions, with a pH-value between 7.5 and 10, and the application with a siz-
ing press is carried out in the dry part of the paper machine. The pH-value
preferably lies between 8 and 9.
The cellulose of the paper web consists, as a conseq-
uence of the invention, preferably of eucalyptus cellulose and pine wood sulfatecellulose, in a ratio of 50 50 to 10:90, preferably 30:70 to 15:85. The degree
of milling preferably lies between 15 and 25 SR.
. .
.~ :
Further chemical auxilliary agents, such as wet and
dry solidifying agents, precipitating agents (fixing agents), synthetic resin
dlspersionsl tensides, colorants and fllling substances, which vary the proper-
ties of the backing paper, can be added to the fibrous substance of the paper
web.
Among the filling substances should be understood white
pigments, such as, for example, TiO2, chalk, and kaolin.
;e ~
"~
.
~'''`"'' ~ .
.
. ,~
- 10- 300/1
1 329~72
Formaldehyde-free wet fixing agents, in a quantity of
1 to 5 weight %, relative to the bone dry fiber substance~ in the form, for
example, of polyamidamine-epichlorhydrine resin, proved particularly favorable
in the sense of the invention, as did an additive of synthetic resin dispers-
ion, on, for example, the basis of acrylic acid ester or styrene-butadine in a
quantity of 1 to 20%, relative to the bone dry fiber substance, and a lesser
addition of tensides for the superior wettability of ~he paper, in a quantity
of less than 0.5%, relative to the bone dry fiber substance.
; In the use of aqueous anionic copolymer dispersion in ac-
cordance with the invention, which can, for example, be synthesized on the basisof acrylic acid, acrylic acid esters, vinylacetate and/or styrol, the dispersed
particles are preferably smaller than 0.2 my, and are of a slight to average
film hardness, and have a lower minimum film formation temperature, preferably
below 30C.
~.i
The ratio between both the copolymerisates of the dis-
persion and the solution preferably amounts to 500:1 to 1:1, preferably 100:1
;
~;~` to 10:1, relative to the effective substance, that is to say, 500 parts of dis-
persion to 1 part of solution to 10 parts dispersion to 1 part solution.
: . .
lt is also possible, within the framework of the pre-
sent invention, to add other synthetic substances, such as, for example, styrene-
butadine mix polymerisate, polyurethane- or polyolefine dispersions, as well as
'~!,.
soaking resin solutions on the basis of urea or melamine-formaldehyde resins in
proportion ~o the impregnation substance.
;~
~}!
.
.~
'
~'
~ 1 329072 3D0/1
Through the use of the mixture, in accordance with the
invention, with a portion of soaking resin solution, the brittle character of
impregnated paper can be reduced.
Also, further auxilliary agents, such as wetting agents,
; viscosity regulators, anti-adhesion and penetration aids, pigments, colorants
and anti-foaming agents can be added to thes2 impregnating substance mixtures.
, . .
Substances are used as wetting and penetrating agents
which alter the boundary surface tension between the fluid phase and solid phase,
for example, tensides and emulgators.
,'~`
In accordance with the invention, the penetration of
the impregnating fluid can be advantageously influenced by a combination of
maleinic acid copolymerisates and these substances which alter the boundary sur-face tension.
:.,
s In accordance w;th the invention, this impregnating
'~J, substance is used in the form of a mixture of soluticn and dispersion, with a
solids content of 5 to 60%, whereby the viscosity lies between 10 and 60 s
X (DIN-beaker, 4 mm~.
,
The application of this impregnating and coating mix-
;~ ture to the non-woven fabric occurs inside the paper machine, in a cylinder
~,v, applying device ~sizing press). Through this, the non-woven fabric, with a dry
content of 98 to 92%, is, in accordance with the invention, conducted through
a siz;ng press~ and the soaking is undertaken on both sides.
.,j
;' ` ' .
, .
`~.'
~ ~ -12- 1 329072 300/1
,
In accordance with the invention, after this first pro-
cess stage of the impregnation, a further surface covering, on one or both sides,
; that is to say, coating~ of the non-woven fabric is undertaken inside the paper
machine with the same, or similarly synthesized, copolymer mixtures, whereby an
intermediate drying takes place between both the individual process stages.
":
Through a subsequently applied coating to one side of
the dried web, a denser surface is achieved, wh;ch ensures a better printabilityor varnishability, or laminability. If only one further surface coating takes
,~
~`~ place on one side, this can be undertaken by rneans of the application of a wiper
blade. A one-sided rolling of the coated paper web can be avoided by means of
an additional to the reverse side.
,'';
~, Such an application can, for example, be a strong aque-
. ,,
`~ ous solution of starch or CI~IC. An additional smoothing of the impregnated web,
wh;ch is coated on one sidel with, for example, knowr, machine smoothing devicesor in a separate work operation in a glazing roller, further increases the de-
sired printability and varnishability of the side coated.
This fiber-containing foil of varying thickness and
s~
varying raw density produced in this manner and way, depending on the pressure
used during the production of the non-woven fabric and smoothing of the soaked
and coated web, is suitable, preferably in close connection with a relatively
rigid and stiff support frame, for example, wood chipboard, as a decorative and
protective casing of furniture parts, such as, for example, television and
radio casings or hi-fi platforms (casing wrapping). By using this fiber-containing
...... .
~ ,.,
`s'
;
,. .
:..
,; . . .
,. ,
-13~ 9 ~0 7 2 3Q0/1
^ foil, which can be manufactured in an economically favorable manner, the disad-
` vantages, previously stated, from the use of PVC or other plastic foils are
avoided.
',.
` The fiber-containing foil with high flexibility,
~;'` dimensional stability under temperature changes, and good blocking properties
~; against water and solvents, produced in accordance with the invention~ is,~ likewise preferably suited for other purposes, such as, for example, as abase material for high~value abrasive papers for wet grinding, printing and
~:. advertising carriers, decorative wall materials (such as, for example, pigment-
ed or unpigmented dimensionally stable tapestries which are difficult to com-
bust), splicing tapes, carrier papers such as, for example, for floor coverings,l.i,
` etc.
:~
;~ The invention will now be illustrated in greater detail
j by means of examples of execution.
: ~,
li' Example 1:
~ ,~
In accordance with the invention, a backing paper with
the following composition and properties is produced as a two-layered paper on
, .,i
~ a duplex paper machine:
~., .
80 X pine wood sulfate cellulose;
:;`
20 % eucalyptus cellulose;
30 SR degree of milling (degree of freeness).
`:
:,,
~,J
. ,: .
'1`
.~
' _
'.......................................... . '
:,
.,~ :
,~ -14- 1 3~072 300/1
Additives which are commercially available
(computed on the basis of bone-dry cellulose):
.:
talcum;
3 % formaldehyde-free wet fixing agent;
,:
~ 0.3 ~ wetting agent and dispersing agent.
;~,
i:
This backing paper with a surface mass of 90 g/mZ was
;~ impregnated on both sides with the synthetic resin mixture,in accordance with
~ the invention, of dispersion and solution in a ratio of 20:1 in a sizing press.
,~.
~ The impregnation effect, which was surprisingly strong with this synthetic
.,~.
resin mixture in accordance with the invention, is particularly characterized
by the layer strength and rigidity under consideration of the water absorption
: to be adjusted, and is also based on a synergistic effect of the dispersion and
~ solution, which, used alone, can not at all achieve the desirably uniform good
,j paper properties.
The following examples confirm this. The adhesive mix-
; tures had to be partially adjusted with water to the optimal viscosity (less
r~ \ :
~ than 6~ s, with DlN-beaker, 4 mm).
,.,
Synthetic resin dispersion alone (aqueous anionic
copolymer dispersion, on the basis of acrylic acid
esters, acrylnitrile and styrol), solids content
,; .
.~,,
~ :
~`J,
',~,~ . '
,
'':
',~''
~~ -15- 1 3~9072 300/1
:. ~
.;. .
~` of 50X, average particle size of approximately
.~- 0.1 ~m, average film hardness, minimal film
~:i
formation temperature below 1C.
~.
................................. 2) Plastic dispersion~ diluted with water, solids
. content of 25%.
3) Plastics solution alone~ diluted with water
~,,,
. (anionic aqueous solution of a copolymer contain-
~ ing carboxyl groups on the basis of maleinic acid
.7 anhydride), solids content of approximately 12~.
' 4) Plastics solution with formaldehyde-free wet fix-
-.; ing agent, diluted with water, solids content of
~ approximately 10'~.
,:~
~ S) Plastics mixture in accordance with the invention,
~ consisting of dispersion (in accordance with ex-
., :
~;l ~ ample 1) and solution ~in accordance with example
3), in a ratio of 20:1, with additions of:
. ...
formaldehyde-~ree wet fixing agent and:
~-3 ~: ~
~ - anti-foaming agent,
.,s.~ ~ .
~ diluted with water to a solids content of approxi-
.,
~ mately 25X.
."
:.
;~i
~''`
....
.
.. .
... . . ~ .
... . .
: . .
. ..
t 3 2 9 0 7 2 ~v~
A B C
l 2 3 4 5
_
D 5S0t 660/ 1050/ 525/ 560/ 1125/
88 140 70 75 155
E ~ 3,5~ 3,32 2,83 2,56 2,89 2,30
F ~ 200 23 28 27 26 25
.
/Key to above chart/:
A ~ Paper characteristics
B = Backing paper
C = Backing paper with sizing press recipe (mixing absorption approximately
15 g/m2)
D = Layer strength, longitudinal/lateral, g/cm
E = R;gidity~ long;tudinal (Kodak-Pathé), mNxm
F - Water absorption, g/m2
,
A pure synthet;c resin dispersion (recipe 1), because
;~ of its good film-forining pro?erties, reduces the water absorption the most
strongly, but the penetration into the backing paper is, however, inadequate.
The values, only slightly ;mproved, relating to layer strength and rigidity,
~ prove this.
;~ Through a dilution of this dispersion with water
(recipe 2), there occurs a greater penetration into the backing paper, with simul-
taneo~sly increased water absorption and still inadequate elasticity of the im-
pregnated paper.
~i
.~
- .:
/
~ . . .
,, ,
.~ .
.. . .
~ -17- 300/1
t ~29~72
The unsatisfactory impregnation becomes noticeable,
' moreover, in an inadequate ripple strength of the paper surface. The impreg-
` nation of the backing paper with the water-diluted svnthetic resin solution
'~A (recipe 3) does, of course9 lead to an improved elasticity, but at the cost,
~
~ however, of a greatly impaired layer strength.
,~:
Also, the addition of wet fixing agents (recipe 4)
s causes no essential change in the properties of the impregnated paper.`i,
.,
$ Through the synthetic resin mixture of dispersion and
solution (recipe 5) in accordance with the invention, the desirably high impreg-
;' nation effects of the adhesive mixture, and thus all desirably good paper proper-
ties,are achieved, these are characterized by a layer strength, about 10~
higher than with recipe 2, relatively low water absorption, and the highest elas-
~' ticity (approximately 10~ lower rigidity than with recipe 3).
This d;sproportionately high impregnation effect~ which
~' was not to be anticipated on the basis of the effect or the individual compon-
ents (dispersion~ solution, wet fixing agent) is to be ascribed to the synergy
of dispersion and solution.
~.s.
;~ Example 2:
'J! In a further series of experiments, the moderately hard
~ synthetic resin dispersion (5) is substituted by a hard dispersion with a par-
`~ ticle size of approximately 0.15 ~m, with a minimum film formation temperature
;
'~
, Ç
. ., ~ , .
.~,'~ .
:~'
.,,
~ 18- ~ 1329~72 300/1
of approx;mately 25C. This dispersion involves an aqueous copolymer dispers-
; ion on the basis of acrylic acid ester and styrol.
"''',;~
The following properties of ~he backing paper thereby
impregnated were attained (the results attained with recipe 5 from the preced-
,
ing series of experiments are repeated again for better understanding):
:;~
.~ A B C
; 5 6 7
. ;. _
D 550/ 1125/ 860/ 1110/
. 75 150 115 148
~- E ~3,50 2,30 3,10 2,76
,
!''.' F ,~,200 25 28 23
, ~Key to above chart/:
,,
~ A = Paper characteristics
;~l B - Backing paper
C = Backing paper with sizing press recipe (mixing absorption of approxi-
mately 15 g/m2)
::~, D = Layer strength, longitudinal/lateral, g/cm
E = Rigidity, longitudinal (Kodak-Pathé), mNxm
F = Water absorption, g/m2
;
:,~ 6) Synthetic resin dispersion, diluted with water,
~, with addition of formaldehyde-free wet fixing
.~ agent, solids content of approximately 25%.
,
~j
`~3 `
..
-19- 1 329~72 ~OU/I
7) Synthetic resin mixture in accordance with the
invention, cons;sting of dispersion and solution
in accordance with example 3, in a ratio of
20:1, with addit;ons of:
. ~ .
- formaldehyde-free ~et fixing agent, and:
. - anti-foaming agent,
j ,:
diluted with water to a solids content of approxi-
;~ mately 25%.
:.~
s !
~ The desired high impregnation effect can not be attain-
ed with a pure synthetic resin dispersion in accordance with recipe 6, as has
', already been demonstrated in recipes 1 and 2. The combination, in accordance
with the invention, of dispersion and solution leads to the desired paper proper-
ties, whereby, because of the high film hardness of the dispersion selected,
:the elasticity of the impregnated paper turned out worse than is the case with
,1 recipe 5.
,:,:
Through a subsequent glaze finishing of this paper in
~accordance with:the invention, the rigidity is reduced by approximately 10 to 20~,
and the~water absorption is reduced by approximately 15 to 20~, while the layer
: strength remalns nearly constant.
, j : ~
.~.i ~ :
~:,
. .,~
. , ,
~",
'
. :
.
' -20- 1 329072 300/1
~ Example 3:
.;,................................... .
..~ In the next series of experiments, the synthetic resin
~` mixture of dispersion and solution in accordance with the invention was used in
.~ combination with a urea-formaldehyde resin in a ratio of 2:1, for the impregnat-
` ion of the backing paper in accordance with example 1.
j~
8) Synthetic resin dispersion alone in accordance
. with recipe 6, in combination with urea-formalde-
'. hyde resin in a ratio of 2:1.
.i
9) Synthetic resin mixture in accordance with the
invention, consisting of dispersion and solution
in accordance with recipe 7 (in a ratio of 20:1),
,,
. in combination with urea resin in a ratio of 2:1.
.,
,,j
~,r, 10) Synthetic resin dispersion alone (aqueous anionic
: copolymer dispersion on a basis of acrylates),
;.; solids content of 50%, average particle size of
~ approximately û.15 um9 average film hardness,
,~:
.: minimal film formation temperature of 12C, in
~ combination with urea-formaldehyde resin, in a
`~; : ratio of 2:1.
11) Synthetic resin mixture in accordance with the in-
:~' vention, consisting of dispersion (in accordance
;.~
..... .
~i~
7`
::.
...
,'
1 3 2 9 0 7 2
with recipe 3), in a ratio of 20:1, in combinat-
~: ion with urea resin in a ratio of 2:1.
.. .
. The propert;es of the impregnated paper obtained are
summarized in the following table:
!.~
A B C
8 9 10 11
,"
~: D 17 18 26 28
E 160114 ~6 140 94
. F ~200 26 20 8~ 27
G 64 126 146 133 144
'. ~ _
/Key to above chart/:
~,~ A - Paper charac~eristics
B - Backing paper
. C = Backing paper with sizing press recipe (solids content 34~)
.,:
~ D = ~lixture absorption, g/m2
E = Porosity, cm3 /min
~$~1 F = Water absorption, g/m2
G - Layer strength, lateral, g/cm
Even comb;nat;ons of synthetic resin dispersions and
soaking resins, such as, for example, urea-formaldehyde resin, are normal
~: ; : for the~;mpregnat;on of decorative backing papers in separate impregnation
devices, lead:to an improvement of the properties of the back;ng paper. The
';
;,
, .: ., .
"
:
... .
...
,
1 329072 ~uv~
type of synthetic resin dispersions used, thus significantly determines the
absorption of mixture, porosity, water absorption and layer strength of the
paper (see recipes 8 and 10).
,
However, with the synthetic resin mixture of dispers-
ion and solution in accordance with the invention, the desired high impregnat-
ion effect, and thus the desired characteristics of the impregnated paper, is
achieved with these special soaking resin-synthetic resin combinations (see
j recipes 9 and 11). Among these are, for example, the considerable reduction
.. ~ in porosity and water absorption, as well as the increase in layer strength.
Because of the relatively high soaking resin portion, however, the level of
.. .
;. layer strength lies somewhat lower than is the case with recipes 1 and 2.
,.~,
~:,
,
. "
~;
,.
~.,
3~'
''``'`
.
,:
,S, ` ,,
.'~'- ' ` ' .
., .
'''''`
.,
',','
