FI69652C - TAPET OCH FOERFARANDE FOER TILLVERKNING AV TAPET - Google Patents

Description

69652

This invention relates to a wallpaper having a raw paper wallpaper layer and a Pigment drip coating layer containing latex and pigments thereon for wallpaper printing methods such as glue, silk, flexo and gravure printing. In order to increase the filling and to reduce the consumption of latex, an aqueous solution of inorganic salts of divalent or polyvalent metals has been applied to the pigment coating layer before printing.

The wallpaper should be sufficiently washable. The Timberley WPM, for example, and method B, in which the abrasive surface is a felt and the medium is a 2% alkaline soap solution, are used to determine the washing resistance. It is considered a reasonable requirement that the wallpaper sample should withstand thirty draws without damaging the surface.

15 Washing resistance can be increased by increasing the amount of latex.

In this application, latex refers to the so-called "latex" commonly used in wallpaper coatings. homo- or copolymer latexes, e.g., polyvinyl acetate homopolymer, polyvinyl acetate-acrylate copolymer, ethylene-vinyl acetate copolymer, styrene-acrylate copolymer, full acrylate, and styrene-butadiene latexes.

In practice to date, it has been found that the addition of more than twenty-five% by weight of the amount of pigments to the pigment drip coating layer achieves sufficient wallpaper resistance.

However, the addition of latex increases the cost of making the wallpaper because latex is expensive.

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It has further been found that when high latex contents are used, wallpaper printing methods generally do not achieve good line sharpness or a smooth compact surface because the ink tends to absorb them, which in turn is due to a deterioration in the absorbency of the pigment coating layer.

Because latex has poor opacity, when the latex content is high, a lot of pigments such as titanium oxide, which has good opacity, must be used to counterbalance it. However, such a pigment is expensive.

In order to overcome the above-mentioned disadvantages, the object of the present invention is to increase the washing resistance of the wallpaper in a way other than by adding latex, whereby the proportion of latex in the pigment coating layer could be reduced. In Applicant's earlier patent application 842025, this object 15 is achieved by applying an aqueous solution of inorganic salts of divalent or more metals, e.g. titanium, aluminum, calcium or magnesium, before printing to increase the washing resistance and reduce the consumption of latex.

The present invention is based on the finding that even when an aqueous solution of polyaluminum chloride or polyaluminium sulfate 25 can be reduced to less than 10% of the amount of pigments while still maintaining the washability of the wallpaper. As the proportion of latex decreases, the cost of manufacturing the wallpaper is substantially reduced because the cost of the added solution is significantly lower than the cost of the omitted latex and the good opacity of its pigment and its printability properties, as described above.

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The chemical formula of polyaluminum chloride (PAC) is Al (OH) Cl n m 3n-m and the molecular weight is 800-900.

The chemical formula of polyaluminum sulfate (PAS) is Al (OH) (SO) n m 4 3n-m and the molecular weight is 800-900. It is preferred that the concentration of the aqueous salt solution applied to the pigment layer is 0.5 to 10% by weight.

It is further preferred that the concentration of the aqueous salt solution applied to the pigment layer is about 5% by weight.

The invention also relates to a method of making a wallpaper, in which a layer of wallpaper raw paper 10 is coated with a pigment coating layer containing latex and pigments for wallpaper printing methods such as glue, silk, flexo and gravure printing. applying an aqueous solution of one or more inorganic salts of divalent or polyvalent metals.

The method according to the invention is characterized in that an aqueous solution of polyaluminum chloride or polyaluminum sulphate is applied to the pigment coating layer in order to increase the washing resistance and to reduce the consumption of latex.

The application can be carried out, for example, on rollers which can be used in various ways known in papermaking technology, or by spraying, in which case air is used in the application of the liquid, or by spraying. Impregnation, i.e. the immersion method, can also be used.

Prior to application of the saline solution, the pigment coating layer is dried to at least touch dry.

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According to a preferred embodiment, the pigment coating layer is applied to the printing paper wet after application of the brine.

According to a further preferred embodiment of the invention, the concentration of the aqueous solution of salt 5 is 0.5 to 10% by weight.

According to another preferred embodiment of the invention, the concentration of the aqueous salt solution is about 5% by weight.

In addition to the above solution concentration, solution application method, and dryness of the pigment coating layer, at least such factors known to those skilled in the art as solution temperature, paper web travel speed, paper absorbency, and absorption accelerators must be considered in order to achieve the desired result. At least some of these, such as the choice of driving speed in the production process, are influenced by other objectives, e.g. production volume, than increasing the washing resistance. Quality aspects must also be taken into account.

The desired result can, of course, be obtained with various combinations of the above quantities. Within the relevant factors known at the time of application, a person skilled in the art can use the information and experiments available to him to choose the most suitable combination.

In the following, the invention is illustrated by a practical example: 5 69652

EXAMPLE

Effect of latex content and treatment with 5% polyaluminum chloride solution on washing resistance The treatment was performed as an off-machine treatment with a rod coating device. The driving speed was 150m / min. 5 hot air dryings were used for drying.

a pigment coating

Latex 25.0 15.0 10 · °

Pigments 100.0 100.0 100-0

Thickener CMC 1.2 1.2 1-2

Washing resistance is not after-treatment.

treated 45 (C) 20 (B) _ (abrasion resistant) Timberley aftertreatment-.

ty 140 (D) 115 (D) 45 (Cj A = washing resistance quite poor B = "insufficient C =" sufficient D = "unnecessarily good (surface too closed)

The constituents of the pigment coating layer are calculated as a dry weight percentage of the amount of pigments.

The purpose of the thickener present in the pigment coating layer is to improve the smoothness of the pigment coating layer. Today, a water-soluble CMC substance, i.e. carboxymethylcellulose, is most commonly used as a thickener. Another property of this material is that it tends to degrade the washing resistance properties of the wallpaper.

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A 5¾ polyaluminum chloride solution is used in the example. It has been found in laboratory experiments that even at a concentration of 0.5%, the effect according to the invention begins to show. Even at a concentration of 2%, the effect is clearly noticeable. The optimum effect, taking into account the various factors, is achieved with about 5% solution. If the concentration of it is increased, the effect on the amount of latex increases slowly. At concentrations above 10%, adverse effects begin to occur, e.g., the treated surface becomes mottled.

It can be seen from the example table that by using the method according to the invention, the proportion of latex in the pigment coating layer has been reduced from 25% to 10%, while still maintaining the washing resistance properties of the wallpaper. At the same time, the manufacturing cost of the wallpaper has been reduced and the printability properties of the pigment coating layer have been improved. It can also be considered an advantage of the invention that, due to the very considerable reduction in the proportion of latex, the thickener can be safely used to achieve a sufficiently good leveling of the pigment coating layer.

The reduced latex content also has the following advantages: The pigment-coated waste paper formed before the treatment according to the invention decomposes easily and can thus be easily returned to the papermaking system.

Equipment used for coating is easier to clean. The biological oxygen demand (BOD) of wastewater is reduced.

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Claims (2)

69652 A wallpaper having a wallpaper raw paper layer and a pigment coating layer containing latex and pigments thereon for wallpaper printing methods such as glue, silk, flexo and gravure printing methods, wherein in order to increase the washing resistance 5 and to reduce the wear of the latex, - or an aqueous solution of inorganic salts of polyvalent metals, characterized in that the salt of the divalent or polyvalent metal is polyaluminum sulphate or polyaluminium chloride. The method of making a wallpaper according to claim 1, wherein the wallpaper raw paper layer is coated with a latex and pigment-containing pigment coating layer for wallpaper printing methods such as glue, silk, flexo and gravure printing processes and to reduce applying an aqueous solution of an inorganic salt of one or more divalent or polyvalent metals, characterized in that the salt of the divalent or polyvalent metal 20 is polyaluminum sulfate or polyaluminum chloride.