FR2487255A1 - WALLPAPER AND PROCESS FOR PREPARING WALLPAPERS WHICH CAN BE REMOVED - Google Patents

Abstract

THE PRESENT INVENTION RELATES TO WALL PAPER. ACCORDING TO THE INVENTION, IT CONSISTS OF OR CONSISTS OF AS A LAYER INTENDED FOR ADHESION TO THE WALL, A SHEET OF A FIBROUS MATERIAL CONSISTS OF 50 TO 100 BY WEIGHT OF CELLULOSE FIBERS AND 50 TO 0 BY WEIGHT OF SYNTHETIC FIBERS. '' AT LEAST ONE THERMOPLASTIC POLYMER, THESE SYNTHETIC FIBERS BEING AT LEAST PARTLY THERMOSWELDED TO ONE ANOTHER, AND THE SURFACE OF THE SHEET INTENDED FOR ADHESION TO THE WALL IS PROVIDED WITH A COATING IN THE FORM OF A SENSITIVELY CONTINUOUS FILM, A 10GM, CONSISTING OF AT LEAST ONE POLYMER OF THE CLASS OF VINYL OR VINYLIDENE POLYMERS, POLYAMIDES, POLYCHLOROPRENE AND CELLULOSE DERIVATIVES. THE INVENTION APPLIES IN PARTICULAR TO THE PRODUCTION OF WALL PAPER THAT CAN BE REMOVED FROM THE WALL.

Description

The present invention relates to wall papers which can be

  removed, that is to say, wall papers having the characteristic of being easily and completely detachable walls they adhere, without having to employ special techniques of scraping, either with or without preliminary wetting of these papers. The detachment can be easily done by hand, and under dry conditions, by simply lifting an edge of the papers in question and applying a pulling force of

  a few tenths of newtons per centimeter.

  Current techniques for obtaining the removability of a wall paper essentially consist in appropriately treating the surfaces to be adhered in order to avoid a strong adherence of the coils or to manufacture two-layer papers in order to obtain easily separating the printed outer layer and the inner layer which remains adhered to the wall, so as to leave it ready for a new applicationcXenfin, to manufacture two-layer paper or multilayer or the innermost layer for the adhesion to the wall, contains synthetic fibers that are melted together,

  quantities generally between 50 and 90% -

  The pretreatment of the surfaces that are forced to adhere is a technique that is generally very expensive because of the work and the materials required, whereas the use of two-layered papers, separable from one another, does not represent not a solution to the problem of removability because after a few successive applications, it is necessary in all cases to remove the whole wall

  by means of expensive manual grinding.

  Even the use of synthetic fibers in multilayer papers, at a high concentration in the wall layer, does not represent an excellent solution because, after thermoconsolidation, the coherence of the layer containing them to the superimposed layer becomes so weak that during detachment, breaks with separation of

  layers of each other are very common.

  The present invention relates to a wall paper, which can be perfectly and easily removed from any wall surface, and it is composed or comprises, as a layer for a wall adhesive, a sheet of cellulose fibers, optionally in a mixture with thermoplastic fibers at least partially heat-sealed to each other, and additionally containing on the surface for adhesion a coating in the form of a substantially continuous film made of a polymer

which will be defined below.

  Such wall paper may be of the "single layer" type, that is to say of the type consisting only of a single elementary sheet of homogeneous composition, or it may be of the "multilayer" type it is of the type consisting of several layers or sheets arranged

  on each other and having different compositions.

  Preferably, the sheet constituting this monolayer paper or, in the case of a multilayer paper, the sheet constituting the layer intended for adhesion to the wall, contains up to 20% by weight of synthetic fibers of at least one thermoplastic polymer. by calculating on the mixture of these fibers with cellulose. Quantities of these synthetic fibers up to 50% by weight can

  be present in all cases in such a sheet.

  However, it is preferable to limit the use of such high amounts of synthetic fibers to multilayered films or they are useful in hot deep embossing of the papers, and possibly to limit this use to the printing layer. It is preferable to use, in the layer of this paper which is intended for adhesion to the wall, amounts of synthetic thermoplastic fibers not exceeding 20% and preferably of between 5 and 20% by weight.

  referring to their mixture with cellulose fibers.

  As mentioned previously, synthetic fibers

  thermoplastics contained in the mono-

  layer or in the layer which is intended for wall adhesion (in the case of multilayer paper) are at least partially welded to each other due to the hot melt. This thermofusion is performed by heating the sheet or the layer to a temperature at least equal to the melting temperature of the polymer constituting the fibers. In the case of multilayer paper, the layers which are not intended for wall adhesion may consist solely of cellulose fibers or only of synthetic fibers made of thermoplastic or non-thermoplastic polymers, or blends of these fibers at all.

  possible, these synthetic fibers possibly being

  are welded to each other by thermofusion.

  The polymer forming the coating on the paper surface for wall adhesion belongs to the classes of vinyl or vinylidene polymers, polyamides, polychloroprene and cellulose derivatives. Such a polymer, under the coating conditions, may or may not be in crosslinked form. Whenever possible, it

  should preferably be in crosslinked or vulcanized form.

  Vinyl or vinylidene polymers suitable for the formation of the above coating are, for example, the following: polyvinyl alcohol, polyvinyl chloride, polystyrene, polyvinylidene chloride, polyacrylonitrile, polyacrylates and polymethyl methacrylates, ethyl, propyl, isopropyl, butyl and isobutyl, copolymers of methyl, ethyl, propyl, isopropylbutyl and isobutyl acrylates and methacrylates with acrylonitrile, acrylic or methacrylic acid, acrylamides or mixtures thereof, copolymers of vinylic or vinylidene monomers corresponding with ethylene, containing up to 50 mol% of copolymerized ethylene. Examples of cellulose derivatives are acetate, nitrate, acetate butyrate and cellulose xanthogenate (viscose). Such a polymeric coating has an included weight

  between 2 and 10 g / m 2 and preferably between 3 and 6 g / m 2.

  It can be prepared by depositing, on the surface for adhesion to the wall, auger dispersions or latices or solutions, in organic solvents, of the above polymers. The concentration of the polymer

  in aqueous dispersions nbst preferably not lower than

  less than 10% by weight and even more preferably between 25 and 60% by weight. The concentration of the polymer in the solution in organic solvents is

  preferably not more than 5% by weight.

  In general, it is preferable to apply the coating in a stamping press, during paper making in a continuous operation using a conventional paper machine, when the sheet

  leaves the first end dry at 90-100% humidity.

  However, such a coating can also be performed on the finished paper, before, during or after

  the print operation, if there is one. When the

  is produced during the printing operation, the roller used for this purpose must advantageously have a notch (considered as the number of notches per centimeter and the depth of the cuts) such that it allows the deposition of a film of coating having weight

previously mentioned.

  If the sheet or layer intended to adhere to the wall contains thermoplastic synthetic fibers, the application of coating is preferably carried out before thermofusion of these fibers. In such a case, when the coating has been applied, the sheet or the layer is heated to a temperature at least equal to the melting point of the polymer constituting these fibers. During this heating step, if the polymer constituting the coating is crosslinkable, it is also possible to cause its crosslinking, according to the known methods for each type of polymer, by virtue of the optional and specific crosslinking agents and / or catalytic systems previously

  added to the latex or the polymeric solution used.

  In the case where there are no thermoplastic fibers, the coating can simply be dried at a temperature generally between 90 and 115 C, or it can be brought to a higher temperature in order to obtain,

  if possible, the vulcanization of the constituent polymer.

  Although it is preferable, it is in any case not absolutely necessary that the polymer, after being applied to the surface of the paper, be vulcanized unless

in the case where it is-irop tacky.

  Thus, the subject of the present invention is a wall paper consisting of, or as a layer for wall adhesion, a sheet of fibrous material composed of 50 to 100% by weight of cellulose fibers and 50 to 0% by weight. by weight of synthetic fibers of at least one

  thermoplastic polymer, these fibers being at least partially

  These surfaces are heat-sealed to each other, and the surface for adhering to the wall of this sheet is provided with a coating in the form of a substantially continuous film weighing from 2 to 10 g / m 2, consisting of at least one polymers of the class of vinyl or vinylidene polymers, polyamides, polychloroprene and

cellulose derivatives.

  Another object of the present invention is to provide a method of forming the above wall paper, which method comprises the following steps: (a) preparing a sheet consisting of or comprising, as a layer for adhesion to the wall, a layer of a fibrous material composed of 50 to 100% by weight of cellulose fibers and 50 to 0% by weight of synthetic fibers of at least one thermoplastic polymer, (b) applying to the surface of the sheet or layer, which is for wall adhesion, a latex or an organic solvent solution of at least one polymer selected from the vinyl and vinylidene polymer classes, polychloroprene polyamides and cellulose derivatives, in amounts as obtained; on this surface, a substantially continuous coating weighing, under dry conditions, from 2 to 10 g / m 2, (c) drying this coating or, if this sheet or layer must contain symmetrical thermoplastic fibers, (d) heating the sheet or the layer to a temperature at least equal to the melting temperature of the thermoplastic polymer constituting these fibers, so as to obtain a melting and welding of at least a portion of these fibers

to each other.

  The preparation of the leaves, which can be mono-

  The layers or multilayers according to step (a) can be carried out with conventional paper techniques, using flat-bed or round-die machines, or with combined type machines starting from aqueous dispersions of the fibrous material. Fillers, pigments, glues,

  resinax materials such as, for example, urea resins -

  melamine-formaldehyde and, in general, the usual additives

  used for the formation of paper may be present in such aqueous dispersions, in admixture with the fibrous maleriau, and consequently, also in

the leaves thus prepared.

  As thermoplastic polymers constituting the synthetic fibers contained in the sheets, or in the case of a multilayer paper, in the layers whether or not for adhesion to the wall, mention may be made, for example, of olefinic polymers, in particular polyethylene, polypropylene and copolymers of ethylene-propylene and, moreover, polyamides, vinyl polymers, crystalline resins, acrylic polymers, polyethers, copolymers formed by the monomers corresponding to these polymers and mixtures of such polymers and or copolymers. In general, all thermoplastic polymers can melt at temperatures below those at which there is an excessive decrease in the mechanical properties of the polymer.

cellulose, are employable.

  The synthetic fibers of such polymers or copolymers, which may be employed for the purposes of the present invention, may be fibers of the traditional type in the form of staple fibers, obtained by extrusion of polymeric materials in the molten state, or by spinning

  in the wet state or in the dry state. However, it is preferable

  to use fibers in the form of fibrils or

  fibrids having a surface area of at least 1 m 2 / g.

  These fibrils or fibrids are products known for a long time as possible substituents of cellulose by the preparation of paper or related materials. In general, they have a length of between 1 and 10 mm, an average diameter (apparent) of between 1 and 500.4. They can be prepared according to various methods which are described for example in British patents

  Nos. 868,651, 1,287,917, 891,943, 891,945, 1,262,531,

  1,355,912 and 1,355,913; in German Patent Applications Nos. 2,208,553 and 2,343,543; in U.S. Patents 3,770,856; 3,750,383 and 3,808,809 and in Belgian Patent No. 789,808; in the French patent No. 2 176 858 and in the Italian patents NO 997 919 and

1,030,809.

  However, traditional fibers of thermoplastic polymers in the form of disordered fibers can be

  used in mixture with cellulose and with these fibrils.

  Inorganic fillers such as, for example, kaolin, silica, titanium dioxide, talc and the like, in amounts up to 60% by weight, must be present in the incorporated state in these compositions.

fibers and fibrils.

  As cellulose fibers, it is possible to use all the fibers usually used in the paper industry for the preparation of papers, cartons and similar products. Mixtures of coniferous cellulose and

hardwoods are preferable.

  The drying step (c) is preferably carried out

2487Z55

  -8 in a continuous paper machine under the usual conditions. If synthetic fibers are present, their thermofusion and any crosslinking of the polymer or copolymer film applied to the surface for adhesion to the wall must be carried out by raising the temperature to an appropriate value by means of heating panels. radiation immediately before saturation. In the absence of fibr-flessynthetics, the

  possible thermal crosslinking of the polymer or copolymer

  mother can be performed by elevating appropriately

  the temperature of the dryer rollers.

  The wall papers forming the subject of the present invention are generally subject to embossing processes, which are performed either directly in the printing machine, when the papers in question do not

  do not contain thermoplastic fibers or after the

  printing, in the embossing machine generally used in the manufacture of vinyl wall papers, when the presence of synthetic fibers in these wall papers may allow, depending on the thermal conditions of use, to obtain more or less deep embossings Once obtained, the wall paper according to the invention can be forced to adhere to numerous masonry works, by means of any wall generally used for the application of traditional wall papers, preferably in a dispersion or aqueous solution such as glues

  animal carbide-based amides, based on carboxymethyl

  methylcellulose or synthetic resin latices and

other.

  The examples that follow are given to illustrate the

  present invention without, however, limiting the scope thereof.

EXAMPLE 1

  In a pulper of pulp and paper pulp together, after introduction into the order of 300 kg of coniferous cellulose, whiten 100 kg of bleached hardwood cellulose and 100 kg of high density polyethylene fibers (melting temperature: 135) having a weighted length. average of 1.5 mm / average diameter of 16 p and an area of

superficial of 6 m2 / g.

  By means of double-disc refiners, the fiber paste at a concentration of 3.5% in water was refined to 30 ShopperRiegel (SR) and then added with rosin resin (glue) with 2% by weight. weight of titanium dioxide, and finally with aluminum sulphate to bring the pH to 5. A preliminary bonding test revealed a Cobb value of 16 g / m2 in 60 seconds. Using this paste and using a continuous flat-bottom paper machine, a paper was prepared, the surface of which was treated in a binder press, with a% wt% latex of a tetrapolymer composed of acrylate. butyl, styrene, methylol derivative of methacrylamide and methacrylic acid (Crilat DR-1465 produced by Montedison SpA). The weight of the paper, after drying / was 140

2 2

  g / m; the weight of the polymeric coating was 3.5 g / m2.

  The paper was then printed by rotogravure, then heated

  at 145 ° C and embossed between cooled embossing rolls

at the water.

  The paper removability test was performed on a paper sample pasted on a sheet of Kraft paper using a carboxymethyl cellulose glue; the force required to effect detachment 72 hours after bonding was measured using a dynamometer. In this case, the detachment was almost complete, without tearing, and the force required was 0.49

and 1.17 N / cm.

EXAMPLE 2

  The procedure was as described in Example 1 but using

  a paste containing only 5% of polyethylene fibrils.

  The amount of cellulose fiber was increased to 95%, leaving the relationship between Ellesnon modified. The amount of the tetrapolymer deposited on the surface was found to be 5 g / m 2. The detachment of Kraft paper has been accomplished and

  the force required was 0.59-1.27 N / cm linear.

EXAMPLE 3

  The preparation described in Example 1 was repeated with the sole exception that the treatment in the encapsulating press was carried out using a polyvinylidene chloride latex instead of the acrylic copolymer of this example. The amount of the dry polymer deposited on the surface of the wall layer was 3.5 g / m 2. The detaching force with respect to Kraft paper was found to be 0.98-1.8 N / linear cm, and the detachment was complete,

years no tears.

EXAMPLE 4

  In a stationary pulper, in the order of 60 kg of coniferous bleached cellulose were introduced with 30 kg of hardwood bleached cellulose and 10 kg of high density polyethylene fibrils similar to those of Example 1. of two cone-shaped refiners working in series, the fiber paste, dispersed in

  water at 2, 5%, has been refined up to 280 Shopper-Rieger.

  After addition of the aqueous solution of amide and melamine resin. (Pastes) The paste was diluted to 1% and discharged into a crate where it was brought to pH = 5 by means of aluminum sulphate. In a similar pulper, 60 kg of Uanchie coniferous cellulose and 40 kg of the same high density polyethylene containing 30% of poach of kaolin powder were added. After having brought to a concentration of 2.5% by weight, the fiber pulp was refined by means of two refiners.

  cone shape arranged in series, up to 280 Shopper-Riegel.

  After addition of 5% by weight of dispersed kaolin prior to

  lable in water and sodium resinate (glue), the dough was poured into a second crate where it was diluted

  at 1% and brought to pH = 5 by means of aluminum sulphate.

  Using a continuous machine equipped with two round molds, a paper was made in two layers (each layer weighing 60 g / m) by arranging these layers so that the press can treat with the latex of the acrylic polymer, 1 1 of a analogously to the case of Example 1, only the surface of the layer containing 10% polyethylene fibrils. The weight of the coating of the dry acrylic polymer thus deposited was 4 g / m. The paper produced was then printed by conventional techniques on the surface of the layer containing 40% polyethylene fibrils, and then heated to a temperature of 1600 C in order to cause the fusion of the fibrils and, at this temperature,

  it has been embossed according to the usual technique.

  The force required to effect the detachment of the Kraft paper, measuring 96 hours from the application using the same glue as that used in Example 1, was 0.589-1.226 N / cm; the

  detachment was accomplished without tearing.

EXAMPLE 5

  Using a continuous flat-table machine, paper was made consisting of 45% high density polyethylene fibrils such as those of Example 1, with incorporation of 30% kaolin, 5% bleached wood pulp , 50% of this cellulosis (cellulosesblanchies

  conifer and hard debasing at a ratio of 60/40).

  The paper, perfectly bonded in mass, also contained 5 parts of kaolin powder for 100 parts of fiber added as external charge mixed with the fibers. During manufacture, a usual surface bonding to an amide press was carried out. From the roll of the machine were obtained 4 rolls of paper of reduced size, of which 3 were used to treat a surface of the respective papers

  with the latex of the butyl] e-styrene acrylate tetrapolymer

  methacrylamide-methacrylic acid used in Example 1,

  at one of the different concentrations indicated below.

  The coating operation was carried out with the air knife technique under similar operative conditions for papers, except for the concentration of the polymer in the latex. The slit of the air knife was -12.2 mm and its pressure 0.049 bar. The feed rate of the papers in this operation was 10 m / min, and the temperature of the drying oven 120 C. After drying, the 4 papers were heated to 145 C and then embossed in the usual manner. Paper ammovability measures

  were performed as described in Example 1.

  The main operating conditions and the results

obtained are given below.

  9 r Coating Weight Concentration- Polymer strength in polymeric detachment Latex% (g / m2) Kraft paper (N / cm) _, 0 0 Not measurable due to tearing, 87 I Not measurable due to tears

11.75 2 1.765

(no tearing)

23.50 4 0.883

(no tearing), I

EXAMPLE 6

  The same paper as that prepared in Example 5 was coated on a surface, after manufacture, in a press

  to be enamelled, a latex of 45% by weight of polymethyl methacrylate

  crylate, instead of the tetrapolymer used in this example. The coating operation was carried out by means of a TH Dixon Engineering machine, model 160, operating at a pressure between the rollers of 35, 32 N / cm, a paper feed rate of 20 m / min, and a temperature of drying capacity of 120 C. The weight of the coating under dry conditions was 3.5 g / m2. A portion of the paper was then brought to a temperature of 145 ° C. The results of the removability tests, carried out as described in Example 1, as well as the characteristics of the paper as such (uncoated) heated to 145 ° C., paper with coating but dried only at 120 C and paper coated and heated to 145 C are

recorded in the table below.

  Paper processing such as paper with paper

  what garment dried garment treated

at 120 C to 145 C

  Detachment force (N / cm) not measurable at 1,962 1,17

cause of tearing

  Cobb Absorbance at seconds (g of water absorbed) 15.7 10.3 7.0 m2 Dennison Waxes (No.) 8 14 23 Air Permeability (Bendtsen) (cc / min) 400 105 15 4 - 'N CO -4 ro tn ni

EXAMPLE 7

  The manufacture described in Example 5 was repeated but excluding the use of polyethylene fibrils and using as fibers a mixture consisting of 5% by weight of Portland stone, 57% by weight of coniferous cellulose and 38% by weight. % by weight of hardwood cellulose. By carrying out a treatment outside the machine using the tetrapolymer latex described in Example 1, an amount of 3.1 g / m 2 of this tetrapolymer was deposited on

  the surface of the paper intended for adhesion to the wall. The opera-

  Coating was carried out under the same conditions as those indicated in Example 6. Tests carried out on this paper as such, on the paper coated and dried at 1200 ° C. and on the paper coated and treated at 1450 ° C. gave the following results:

  Paper such as paper with paper coated paper

  Treatment which garment, just treated at 145 C dried at 120 C Cobb Absorbance at seconds (g / m2) 14.5 11.5 8.5 Dennison Waxes (No.) 16 18 26 Permeability to air, Bendtsen ( cc / min) 240 25 15 Kraft paper detachment force (N / cm) Tear 2.45 1.57 o rS Co rS tUn

Claims (9)

R E V E N D I C A T I 0 N S CLAIMS   1. A wall paper characterized in that it consists or contains, as a layer for adhesion to the wall, a sheet of a fibrous material composed of 50 to 50% by weight of cellulose fibers and 50% by weight of cellulose fibers. 0% by weight of synthetic fibers of at least one thermoset polymer   said synthetic fibers being at least partially   heat-sealed to each other, and the surface of the wall-adhering sheet being provided with a substantially continuous film coating, weighing from 2 to 10 g / m 2, consisting of at least one polymer of the class of vinyl or vinylidene polymers,   polyamides, polychloroprene and cellulose derivatives.   2. Wall paper according to claim 1, characterized in that the aforementioned synthetic fibers consist of 2 / g   fibrils having a surface area of at least 1 m2 / g.   Wall paper according to one of the claims   1 or 2, characterized in that the aforementioned coating has a weight between 3 and 6 g / m2.   4. Wall paper according to any one of the claims   1 to 3, characterized in that the abovementioned vinyl or vinylidene polymer is a polyvinyl alcohol, a polyvinyl chloride, polystyrene, a polyacrylonitrile, a polymethacrylate, or a polyacrylate of methyl, ethyl, propyl, isopropyl, butyl] isobutyl or a copolymer of a methyl, ethyl, propyl, isopropyl or butyl or isobutyl acrylate or methacrylate with acrylonitrile, acrylic or methacrylic acid, an acrylamide or mixtures of these monomers, or a copolymer   such acrylates or methacrylates with ethylene,   up to 50 mole percent of copolymerized ethylene.   Wall paper according to any one of the claims   1 to 3, characterized in that the above-mentioned cellulose derivatives are composed of acetate, nitrate, acetate-butyrate and cellulose xanthogenate.   Wall paper according to one of the claims   characterized in that the aforementioned synthetic fibers are present in an amount not exceeding   % by weight in the mixture with the cellulose fibers.   7. A method of manufacturing a wall paper according to claim 1, characterized in that it comprises the following steps: (a) preparing a sheet consisting of or comprising as a layer for adhesion to the wall, a layer of a fibrous material composed of 50 to 100% by weight of cellulose fibers and 50 to 0% by weight of synthetic fibers of at least one thermoplastic polymer, (b) applying to the surface of said delivery sheet for adhesion to the wall , a latex or a solution in an organic solvent of at least one polymer selected from the classes vinyl polymers or vinylydene, polyamides, polychloroprene and cellulose derivatives in an amount such that one obtains on said surface a substantially continuous coating weighing, under dry conditions, from 2 to 10 g / m 2; (c) drying said coating or, if said sheet or layer must contain thermoplastic synthetic fibers, (d) heating said sheet or layer to a temperature   at least equal to the melting temperature of the thermo-   plastic material constituting said fibers, in order to obtain a fusion and a welding of at least a portion of said fibers to each other.   Process according to claim 7, characterized in that the aforementioned latex has a concentration of polymer which   is not less than 10% by weight.   9. Process according to claim 7, characterized in that the aforementioned latex has a concentration of polymer which   is between 25 and 60% by weight.