DE1546450A1 - Coated paper and process for its manufacture - Google Patents

Description

Patent attorney "D AQ ζ ~

ZielitaUstrafle 139

Expl.

Sooiet ^ anonymous dite;

Les Pet it s "-Pi Is de Leonard DANEL,

69, rue du Docteur Calmette, LOOS (North) France,

Coated paper and process for its manufacture.

The present invention relates to coated paper and as a novel industrial product the method of its manufacture.

There are already coated papers known in which at least one of the surfaces covered by at least one thin film-like layer of microporous structure which consists essentially of a synthetic resin.

Certain of these known coated papers have a coating layer which consists essentially of a synthetic resin, in particular a thermoplastic type, or also contains a plasticizer, which may be heat-sensitive. A cover of this kind.,

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which is usually opaque and milky white, is locally under the action, pressure and / or transparent to moderate warming. A backing paper with a dark tint covered with a coating layer of this type is permitted accordingly to apply inscriptions without ink, with the help of a writing device such as a possibly heated pen, by applying pressure and / or heating to the free surface of the coating layer. A special manufacturing process of coated paper of this kind is in particular in the patent no. 1 312 4-53 * filed September 6, 196I, and in its first supplementary application No. 81,200, filed September 2, 1961. February 1962, described.

In the case of other known coated papers of this type, the coating layer generally consists of one little or no plastic resin, so that this layer has a relatively high resistance to mechanical and has thermal effects. To the extent that the synthetic resin that makes up the coating layer has an affinity for printing ink, it is able to produce it quickly, intensely and on a to absorb great depth due to its microporosity. A paper coated with this type of coating is covered, is therefore particularly suitable for printing, for which it is very advantageous to use the usual art print

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. replaces papers that have a coating based on " Have mineral substances and accordingly heavy and are costly. A coated paper of this type is described in particular in the patent application, on September 12, 1963 for "art paper" and in particular it can be prepared by the process described in the above mentioned patents.

In all of the above-mentioned patent applications, the weight per surface unit depends, and accordingly the The cost price of the coated paper depends to a large extent on the thickness of the coating layer must be given so that it has sufficient opacity to the backing paper, which may be of dark tint is to be covered completely. However, the opacity of the above-mentioned coating layers is almost exclusively due to the numerous Reflections of the light rays on the walls of the smallest cavities, which are filled with air and located in said microporous coating layers. In the case of a plastic coating film, it is in fact the local-compression of said inner cavities, that by making it the coating film makes it locally compact, at the same time makes it practically transparent. The known coating layers that mentioned above, are not the cheapest

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Structure to create a strong opacity at a very low strength. According to the manufacturing process , the coating layer are those with air filled cavities that this layer encloses, or the solid particles that delimit these cavities, in fact of substantially spherical shape, so that for the volume they occupy the offer the smallest possible reflective surface. On the other hand, said voids or particles have a lot ^ different dimensions, which damages the overall opacity of the film.

The present invention allows the previously mentioned coated papers to be improved by the thickness to be given to their coating layers is reduced to a certain degree of opacity to achieve.

The coated paper according to the invention is of the kind and fact initially indicated characterized in that the internal voids of its coating layer are mainly composed of microscopic gas bubbles Dimensions are formed that are essentially the same

! shaped and fixed by adsorption on solid particles

j, whereby these particles are also of microscopic dimensions and consist of at least one mineral, j in particular metallic, insoluble component,

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for example a metal oxide or metal hydrate, and which approximately uniformly and with a high Density are distributed over the entire extent of the synthetic resin film.

With the same thickness, the coating film of the coated paper according to the invention has an opacity which is clearly superior to that of the layers of coated papers as they have been produced up to now, and this essentially for the following reasons: Cavities λ

of the coating layer are fixed by adsorption to solid particles and are not spherical Shape so that, for a given volume, they offer a reflective surface area larger than the minimum that corresponds to the spherical shape. On the other hand, the opacity achieved is reinforced by the fact that all of the internal voids of the coating film are essentially the same Have dimensions. Finally, the solid particles of the mineral components make up the coating layer coated paper according to the invention even more opaque, all the more so as they are more reflective, especially in the case of particles of metal compositions. Thanks to its very strong opacity, the coating layer of the coated paper according to the invention to an extremely low strength

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on the order of "12 to 15 / u, and as light in weight as about

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• 5 g / m - the coated paper according to the invention,

which is suitable for all known fields of application that have been mentioned above, accordingly has a extremely low weight per surface unit and accordingly a very low cost price. this is not only due to the fact that it is used to form its coating layer per unit area only very small amounts of commercially available and cheap * substances (resins, metal oxides) are required, but on the possibility of using a thin, light base paper due to the very low weight of the coating layer To use paper, which may also be of mediocre quality and therefore very cheap. In the case where the coating film of the coated paper of the invention is made so that it is plastic and in particular thermoplastic, is its sensitivity to pressure and / or heating by a writing organ such as a stylus, much greater than the corresponding sensitivity of the thicker coating layers of the coated paper of the same kind that have been produced so far.

The present invention also relates to a manufacturing method of the above coated paper. This manufacturing process exists

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in a known manner in it, on the backing paper to apply a coating layer, the one liquid has volatile phase and a dissolved or very highly dispersed phase, which is essentially consists of a plastic, then the coated To dry paper, for example, by the action of a preferably hot air stream.

The manufacturing method of the coated paper according to the invention is characterized in that a liquid coating is produced, which apart from the ™

Synthetic resin contains a second dissolved or very highly dispersed phase, which consists essentially of consists of a metallic composition selected to be hydrolyzable to form an on-site release of gas and an additional insoluble metallic composition, possibly a metal oxide or metal hydrate, after which, before the coated paper is completely dried, the metallic composition is hydrolyzed, which |

is contained in the liquid coating layer which has been applied to the carrier paper. The hydrolysis of the ₍ 'metallic composition which is contained in the liquid coating that is deposited on the paper carrier, so at the same time the formation generates a Gasfieigabe in place and depositing a * r insoluble metallic composition in very

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fine particles. As a result of the essentially uniform dispersion of the hydrolyzable metallic Composition in the liquid phase of the coating layer find the formation of a gas bubble and the • Precipitation of a particle of insoluble metallic composition under conditions of close proximity not only in time but also in space, so that said gas bubble remains absorbed, i.e. superficially on the. solid particles fixed at the same time and was formed near them. These

^ Appearance explains the special structure of the coating layer of the coated paper of the invention so that the advantages mentioned above can be achieved were specified.

The hydrolyzable metallic composition that contained in the liquid coating material deposited on the backing paper is preferred among the metallic carbides, nitrides, and hydrogen compounds and the organic ones P metallic compositions selected.

According to a particular embodiment of the process for producing the coated paper according to the invention is the hydrolysis of the metallic composition caused by the moisture in the drying air. In another embodiment

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This process causes the hydrolysis of the metallic composition by water that is in place and site was formed by a chemical reaction between two substances, e.g. one Hydrogen peroxide and a reducing agent, which are added to the liquid coating, whereby this reaction before the coated paper is completely dried by the supply of thermal energy is triggered, either directly or through the conversion of some other type of energy (electrical, electromagnetic, radiation, ultrasound .... etc.). This method allows easy and to precisely dose the total amount of water that is formed on the spot.

Finally, the liquid phase preferably consists of the coating layer coated on the carrier paper of at least one volatile organic liquid, free of water and chemically neutral towards the q & he and the other components of the Coating layer.

Several embodiments are exemplified below of the manufacturing process of coated papers according to the invention.

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Example 1 - 85 grams of vinyl chloride and copolymerized maleic ester and 19 grams of a plasticizer are dissolved in 1 kg of methylene chloride and 0.5 g of finely powdered calcium hydride is added to this solution. This suspension is then refined and homogenized by grinding in a ball mill for approximately 2 hours. After that she is used to

To cover 17 m of an ordinary paper of dark color, which is then dried in a tunnel, which is passed through a stream of air which has a temperature in the range of 50 ⁰ C and a relative humidity of about 90 $. Drying can be ended when the coated paper is passed over corresponding heated cylinders.

The moisture brought in by the drying air is what is present in the liquid coating Calcium hydride is hydrolyzed according to the following rule:

1) CaH ₂ + H ₂ O ν 2H ₂ + CaO;

each of the calcium hydride molecules contained in the liquid coating has accordingly been dissociated with the formation of two gaseous hydrogen molecules and a GaO molecule. Because these three molecules © under conditions of spatial and temporal proximity are formed, at least one of the two gaseous molecules is duroh adsorption on the solid CaO molecule remained fixed. To the same extent

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in which the calcium hydride particles contained in the liquid Coating are dispersed, microscopic dimensions. this also applies to. the CaO formed Particles and the gas bubbles, which are fixed to them by adsorption, so that the dry coating has a microporous structure, the inner cavities of which are made more microscopic by small gaseous bubbles Dimensions are formed. The nature of the formation of these voids explains that they are essentially all have very similar dimensions and that, as a result of their adsorption on solid particles, their shapes change differ significantly from the spherical shape.

The coating film coated on the paper support by the method described above has an extremely small thickness of 11 to 15 fju and is also very light in size.

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Order of 5 to 6 g / m · The layer is nonetheless opaque enough to completely hide the backing paper of dark color and give it a perfectly white appearance. This coating film is. sensitive to the effect of pressure and heat, which are exerted, for example, with the help of a writing pen, and make the paper locally transparent, whereby the carrier paper appears dark in color. Such a paper is therefore perfectly suitable for recording inscriptions with the help of a writing organ,

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which is not loaded with ink, for example with the help of the pen of a recording device. It is also perfectly suited to make copies of documents without the usual carbon papers must be used, since the writing pressure in this case simply by means of the letter, for example a typewriter.

In the method described above, the calcium hydride can be replaced by a different metallic composition be replaced, which is chosen so that it is hydrolyzable with the release of a gas In place and forming another insoluble metallic composition in the liquid phase of the coating, for example a metal oxide or metal hydrate: The calcium hydride can accordingly be replaced, for example, by another metal hydride or by metal carbides, metal nitrides, which meet the above conditions. In the case of aluminum carbide, for example, the reaction would be the used hydrolysis the following:

2) Al ₂₁ C ₇ + 12H ₂ O 3CH ₁ , + H kl (OH) y

in this case the gas bubbles initially formed are due to the simultaneously formed aluminum hydrate parts Are adsorbed, methane bubbles are to the extent to which the density of the resulting

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Cavities essentially that of aluminum carbide that was initially dispersed in the liquid coating layer is sufficiently large that the named cavities are in connection with each other and accordingly also with the free surface of the coating, the methane initially filling these cavities is eventually replaced by air. Magnesium and Lithium hydride, calcium and lithium carbides, calcium and magnesium nitrides, etc. can be used in, for example the method according to the invention are used,

the ™ formed in place by their hydrolysis Gas bubbles depending on the cases hydrogen, methane, ethane, acetylene ... etc. or also nitrogen, ammonia; which are eventually replaced in the cavities by the atmospheric air.

The Kurfibharz that forms the basis of the coating layer after ■ the invention, among the cellulose esters or -Äthern, polyvinyl! To, polyesters, natural or artificial Kautsohuk, various copolymers, etc. etc. ...

to be selected.

In the example described above, the synthetic resin is dissolved in a volatile organic liquid (methylene chloride) and the metallic, hydrolyzable composition is suspended in this same liquid, but ISg is also possible to use. <i hydrolysable metallic accessories

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optionally in an organic volatile liquid different from that in which the synthetic resin is dissolved, whereby the two solutions must then be miscible in order to create the liquid coating to build. In addition, the synthetic resin itself can be suspended in the organic liquid or liquids which form the liquid phase of the coating layer in which the hydrolyzable metallic composition dispersed or dissolved. In any case, the liquid phase of the coating material must consist of a or more volatile organic liquids, free of water, to soften the backing paper to prevent and also chemically neutral to the latter as well as to the others Components of the coating material (synthetic resin, \ hydrolyzable metallic composition and various additives, for example in the case of at least one of the solid components the liquid coating layer is in suspension, an anti-sedimentation agent such as amine salts, Xantogens ,,, etc.),

Example 2 A so-called Grignard solution is produced from magnesium methyl iodide by mixing, for example, 200 g of ethyl ether, 71 g of methyl iodide and 12.2 g of magnesium. On the other hand, 100 g of polyvinyl chloride are dissolved in 1 kg of methylene chloride and in this solution with

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8 gr of the magnesium methyl iodide solution and 25 grams of dibutyl phthalate mixed together. After filters the mixture is used to keep it even

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To coat 20 m of a carrier paper of dark color. This paper is then dried as described in Example 1. The one brought in by the dry air. Moisture causes the hydrolysis of the magnesium methyl iodide. according to the following reaction:

>). 2HC ^ MgI +2 H ₂ O - 2CH ^ + Mg (OH) ₂ + MgIg j

The process of forming the voids is the same as described in Example 1, the coated paper obtained also having extremely similar properties having. The magnesium methyl iodide used in this example can be replaced by another suitable one hydrolyzable organometallic composition are replaced. -

The pressure sensitivity of the coated _p aplere,

prepared according to the previous two examples is related to the fact that their .The coating layer has a microporous and plastic structure, the proportion of the metallic composition, The amount dispersed in the layer is low enough to reduce the plasticity of the synthetic material used Do not reduce the resin excessively. In these examples is in fact the percentage of metallic

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Composition that disperses in the coating layer is, below 6 percent by weight. The heat sensitivity of these coated papers according to the invention can may be increased, in particular to include records to be carried out with the help of a heated pen or by the action of a thermal one or ultrasonic radiation (partly for example

^: by a shield) by making the; Coating layer a highly thermoplastic resin is selected, or by adding a plasticizer, which is optionally heat-sensitive, to a resin of medium plasticity. For these areas of application, the proportion of the mineral composition that is in the

^} Coating layer is dispersed, preferably still j less than 6 percent by weight.

The present invention relates to a coated paper as a novel industrial product, whose microporous coating film is practically insensitive to mechanical effects and moderate thermal effects

Actions is. Such a paper is particularly suitable for printing because of its ability, in particular, to absorb the printing ink in an intensive, rapid manner to a great depth, namely because of the microporous structure of the coating layer. This paper • can accordingly replace the so-called "art paper" for printing, compared to which the paper has the essential advantage of a significantly lower weight and

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has a significantly lower cost price per unit area. These advantages are related to the fact that the coating film which is produced according to the method of the invention has a greater opacity than that of the coating layers which have generally been used up to now for the production of conventional art papers and those of the im generally based on mineral compositions. With the same quality art paper can accordingly a coating layer substantially lower strength than the exhibit the usual art papers, for example of only 12 to 15 / ^ ·> according to the invention thus gives the paper a very low weight at most equal to 5 gr./m ² . As a result of its low weight, such a film can be carried by a very thin, very light carrier paper, which may be of medium quality, in particular a wood paper of about 20 grams / m ^2, ie which is significantly thinner and lighter and therefore substantial less expensive than the papers used as a carrier for the common art papers. The coating film of the art papers according to the invention differs from that of the papers according to the invention only by the proportion of Mineralzusammeriöetzungen located üich therein, since this share \ m fcrsteren case is considerably high and in particular iswiijohen 2o and 4o Gewichtöprozent, lies NODAI; 'Uo überaugnsjohLfh'r. wenent I. Ui ti wlümTit '> n <l.ifäiii ^ yi. ¹ ><■ night 'ii.rd, Lwrtwiomicii'v \ ·, 0 [>) κη pressure, K; .- m ,: -' -n u> iU ί'-ΐ; ¹ »L, YULi same Ζί; * κ: ίίθ batiliail ο In Ln!, ^{Oi '::} ; ä ;; ·; '[iwauj

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to use resin that is slightly or not very soft •, especially synthetic resins with a high degree of softness Degree of polymerization or polycondensation. Finally ' the type of resin must be chosen so that it corresponds to the chosen color, especially in the case of a Printing ink. For an aqueous or hydrophilic vehicle paint, a hydrophilic resin must be chosen, such as Methyl cellulose, while a lipophilic resin must be selected for a color with a fatty or oily carrier, such as polyvinyl chloride or polyvinyl chloroacetate, polystyrene ... etc. as specified in the patent application, filed on September 12, 19β3 and already mentioned above.

The method according to the invention also allows a type of coated paper to be produced that is particularly suitable for reproductions and whose features are specified in the patent application, which was filed on May 18, 19β2 for "coated Sheets of paper, especially for reproductions ", These back and front coated sheets of paper allow the transfers on the back of a first one coated sheet made entries on the front of at least one other coated sheet Sheet of paper that is placed under the first, as one of its surfaces is covered with at least one thin, crumbly and little 3chioht adhering to the paper

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is provided and its other side with a thin, the layer adhering well to the paper, these two layers being made so that they are locally attached to one another Adhere to the places where the two sheets of paper placed one on top of the other are exposed to the pressure of writing so that the corresponding parts of the poorly adhering layer of one of these two sheets pass through the adherent layer of the other sheet will be lifted off when they are later separated.

Although the manufacturing method according to the invention on all of the embodiments of the coated paper sheets disclosed in the aforementioned patent application are applicable described below, only a manufacturing method for leaves is described below, the front of which is covered by a layer that adheres well to the paper, while the back is covered with a thin layer of a coloring substance is provided, namely of a color which is different from that of the layer of Deviates from the front, or, if the latter is transparent / from the surface of the paper carrier to which the layer is attached, while this shifeht with coloring substance itself through a little adhesive Layer is covered, with the two layers, both the adherent and the less adherent one have the same microporous structure, while the former is made to be tough is and the ^ further bo that it is crooked. the Use a papleree of this type that is on his

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both surfaces is coated, for reproductions is shown in Fig. 2 of the aforementioned patent application so that it is not "necessary to give details about it here.

Example ^ :

The back of a strip of 20 m ^{2 of} paper is coated with an aqueous suspension of blackness, to which a wetting agent may have been added, so that, after drying, a

™ adhesive layer of carbon from a weight of 1 to 1.5 gr./ffl2 is achieved. After that, 9 ° grams Polyvinyl chloroacetate dissolved in one kg of dry methylene. This solution will be three grams of cumene Hydrogen superoxide, 1.2 grams of propylamine and 0.5 grams : Calcium hydride added, which is replaced with 0.75 grams of calcium carbide or G grams of the Grignard solution that is mentioned in example 2. With the mixture obtained, the one already coated with blackness becomes

The surface of the paper tape is evenly coated. Thereafter this liquid coating layer is partially dried and then the paper tape is over an infrared radiator out, which is arranged transversely to the paper tape. The heat received by the still liquid coating layer, there causes the reduction of the cumene hydrogen superoxide by the propylamine, and so on site and Spot formed water instantly hydrolyzes the calcium hydride, or the equivalent metallic composition according to reaction no. 1 above.

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Obviously, this allows the amount of water released on site in the liquid coating layer to be adapted in a particularly precise manner to the amount of the metallic composition which has to be hydrolyzed and is dispersed there. The supply of VJ poor energy to the deposited liquid coating layer on the paper carrier, which is necessary to trigger the reduction of the hydrogen peroxide, can also be a direct effect through contact or can result from the conversion of another type of energy, in particular electrical energy (electrical spray discharges) electromagnetic energy (electrical high frequency field) ultrasonic energy ... etc. Of course, the formation of water on site can not only be achieved by a reduction reaction, but also by any other suitable chemical reaction between two suitable, appropriately selected additives of the liquid coating . The hydrolysis reaction is accompanied by opacity of the coating which, once dry, is friable. The as yet uncoated front side of the paper tape is then coated with one of the solutions given in Examples 1 and 2, and drying is then carried out under the conditions as given in Example 1. The layer deposited in this way on the front of the paper is not friable, wio dlo fjohloht, which is deposited on äoi · llüoAwoitc , yiotm au- V'ji'florsölte and dl.c iiU <! KrjüLt>"" from sv /egg

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from the paper tape whose production has just been described, cut sheets are placed one on top of the other then it can be determined that the two microporous layers that would be placed against each other adhere to one another, especially under the effect of pressure and that with the separation of the two sheets the fractions of the friable layer of the back of one of the leaves from the non-friable layer the front of the other sheet, as well as the corresponding fragments of the intermediate layer the blackness of the reverse side of the first sheet, the adhesion between the two coating layers can still be can be increased by increasing the amount of plasticizer that is contained in the adherent and non-friable Layer of the front is located, or in which an adhesive mass is added.

The adherent, non-friable layer of the front can also be made by using the same solution is used as for the crumbly layer on the back, but using this solution Plasticizer is added, in particular 20 grams of plasticizer in the case of the numerical example given above. The hydrolysis and drying operations are then the same as for the preparation of the two microporous layers of the front and the back.

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Claims (1)

P A T .E N T A N S F RÜ CH E. ' 1.) . Coated paper, of which at least one of its surfaces is covered with at least one thin coating with a microporous structure essentially made of a synthetic resin; characterized in that the internal voids of the coating film are mainly composed of ^? gaseous bubbles of microscopic dimensions and substantially in ^c uniform type are formed, which are fixed by adsorption on solid particles also of microscopic dimensions and at least one mineral component, in particular of a metallic nature and insoluble consist of, for example, a ^r metal oxide or metal oxide hydrate and which are distributed almost uniformly and with a high degree of impermeability over the entire surface of the said synthetic resin film. 2.) Coated paper according to claim 1, characterized in that the mineral composition consists of the insoluble metallic compositions are selected that can be produced by a hydrolysis reaction, which creates a release of gas in place, especially among the carbides, nitrides, hydrides of metals, organometallic compounds ... etc. j3.) Coated paper according to claim 1, characterized in that that the coating layer in a known manner essentially consists of a synthetic resin in particular thermoplastic type or also contains a plasticizer, which is optionally heat-sensitive and that the coating layer is low _m2> 009829/1203 EAD OF.iG Percentage by weight of the mineral composition preferably contains j less than β £ ί. 4.) Coated paper according to claim 1, characterized in that the coating layer in a known manner and way consists essentially of a resin with little or no plasticity and that it is a strong one Contains weight percentage of the mineral composition, preferably between 2o and 4o $ above. 5.) Coated paper according to claim 1, characterized in that the two surfaces of the carrier paper are coated in a known manner, one by an adhering film of a plastic coating, which in particular contains a small proportion of mineral composition and / or an adhesive substance and the other side is provided with a non-adherent coating film which is friable and contains, for example, a greater proportion of mineral composition, a film of low cohesion of a color substance, which is optionally introduced between the base paper and the friable coating film. 6.) Coated paper according to claim 1, characterized in that the coating film has a weight in the order of magnitude of 5 grams / m ² and a thickness which is in the range from 12 to 15 λα. 7.) Production process of the coated paper according to one of the preceding claims, which consists in -24- 009829/12 0 3 to deposit a coating layer on the paper support, which consists of a volatile, liquid phase and a dissolved and very dispersed phase, the is essentially formed from a synthetic resin and then the paper, for example by the action a preferably hot air stream to dry, characterized in that a liquid coating layer is produced, which contains a second dissolved or very dispersed phase in addition to the synthetic resin, the essentially of a 'metallic composition. exists, which is chosen so that it is hydrolyzable is with a gas release in place and another insoluble metallic composition for example a metal oxide or metal hydrate, followed by complete drying of the coated paper the metallic composition is hydrolyzed, the contained in the liquid coating layer, the is deposited on the backing paper. ö.) The method according to claim 7, characterized in that the hydrolyzable metallic composition is selected from the metal carbides, nitrides, hydrides and organometallic compositions, ] 9.) The method according to claim 7, characterized in that the hydrolysis of the metallic composition takes place by the moisture that is in the drying air. lo,) Method according to claim 9 * characterized in that " ⁵ " 0 0 98 2 9/1 2 0 3 bad original that the drying of the coated paper by a Air flow occurs that has a temperature close to 50 ° C and a relative humidity that is close to $ 90. 11.) The method according to claim 9, characterized in that the hydrolysis of the metallic composition is effected by water which is formed on the spot by a chemical reaction between two substances, for example a hydrogen superoxide and a reducing agent, which are added to the liquid coating layer before the coated paper is completely dry, this reaction is triggered by the supply of thermal energy, which is either supplied directly or results from the conversion of some other type of energy (electrical, electromagnetic, radiation, ultrasonic energy ... etc.). 12.) The method according to claim 1, characterized in that that the liquid phase of the coating layer, which is deposited on the carrier paper, preferably off there is at least one volatile organic liquid that is anhydrous and chemically opposite to the Paper and the other components of the coating layer is neutral. -26- 009839/1203