DE10057294C1 - Decorative raw paper with high opacity, as well as decorative paper or decorative film - Google Patents

Abstract

A decorative base paper for decorative coating materials contains a pigment mixture of titanium dioxide and talc, the talc having a grain size distribution D50 of less than about 3.0 μm and both the decorative base paper and the decorative paper have a high opacity.

Description

The invention relates to a decorative base paper, the one Contains pigment mixture of titanium dioxide and talc as well decorative coating materials obtained therefrom.

Decorative coating materials, so-called Decorative papers or decorative films are preferably used Surface coating in furniture manufacturing and in Interior fittings used. Decorative foil is understood a resin-impregnated or resin-impregnated and surface treated, printed or unprinted Paper web. Decorative films come with a backing plate glued or glued.

A distinction is made depending on the type of impregnation process between decorative foils with impregnated paper core and pre-impregnated decorative foils, where the Paper in the paper machine online only partially is impregnated. Laminates (high pressure Laminates) are laminates made by pressing several impregnated, stacked papers arise. The structure of these laminates consists in general from a highest surface resistance producing transparent overlay, one resin-soaked decorative paper and one or more phenolic resin kraft papers. As a document for this hardboard and chipboard, for example as well as plywood used.  

For those manufactured using the short cycle process Laminates (Low Pressure Laminates) with synthetic resin impregnated decor paper directly with a base, for example a chipboard, using a low pressure.

That with the coating materials mentioned above Decorative paper used is white or colored with or used without additional printing.

On so-called decorative base papers as starting materials for Manufacture of the above coating materials there are special requirements such as high opacity for better coverage of the underlay, even Formation and grammage of the sheet for an even Resin absorption, high light resistance, high purity and Uniformity of color for good reproducibility of the pattern to be printed, high wet strength for one smooth impregnation process, corresponding Absorbency to get the necessary Resin saturation levels, dry strength, which at Rewinding processes in the paper machine and during printing in the printing press.

DE 197 28 796 A1 relates to a base paper for the Production of decorative surfaces with a percentage of at least 80% by weight hardwood pulp on Total paper pulp, 2 to 4 wt .-% mineral Filler and 3.7 to 4.2 wt .-% starch. The mineral The filler can be titanium dioxide. DE 199 12 149 A1 relates to a decorative base paper with improved Dry strength, its pulp one Pulp mixture of an unmodified and a contains cationically modified pulp. The amount  the filler, for example titanium dioxide, in this Decorative base paper can be up to 55% by weight.

Decorative base papers generally consist of bright white Sulphate pulps, mainly from hardwood pulp, up to 45% by weight of pigments and fillers, based on the Weight of the base paper, as well as wet strength agent, Retention aids and fixatives. decorative base paper differ from usual papers by the very much higher filler content and the lack of one when Paper with normal mass sizing or surface sizing the known sizing agents such as alkyl ketene dimers.  

Opacity is one of the most important properties of the Decorative base. This indicates the masking ability towards the document.

A high opacity of the decorative base paper is due to the White pigments added. As a white pigment usually used titanium dioxide. This pigment ensures high opacity and good brightness and whiteness of the decorative base paper. However, it is disadvantageous the high price of titanium dioxide.

With the partial or complete exchange of Titanium dioxide from other white pigments becomes one Worsening of these properties is achieved. A Adjustment of the opacity is only possible by increasing the Achieve pigment content. The pigment content can be but don't increase it arbitrarily, because in this case with a Impairment of physical properties such as Retention behavior of the pulp suspension, Strengths, lightfastness and resin absorption are to be expected is.

The object underlying the invention is an inexpensive decorative paper with a high opacity with a reduced titanium dioxide content provide.

This task is solved by a decorative base paper for decorative coating materials, the one Contains pigment mixture of a titanium dioxide and talc. The talc used according to the invention is very narrow Grain size distribution with a D50 of less than about 3 µm.  

This means that 50% by weight of the talc particles unite Have diameters less than about 3 microns. Especially talc with a particle size distribution D50 is preferred less than about 2 µm.

The specific surface area of the talcum used according to the invention is greater than approximately 30,000 m ² / kg, in accordance with a particularly preferred embodiment greater than approximately 40,000 m ² / kg. In contrast, the specific surface area of conventional types of talc is in the range from 8,000 to 16,000 m ² / kg. The specific surface was determined according to DIN 66126.

The proportion of talc in the pigment mixture is preferably at 0.1 to 25 wt .-%, based on the Total pigment content.

That in the pigment mixture of the invention Titanium dioxide contained in decorative base paper can be a Titanium dioxide commonly used in decor papers his. Such titanium dioxides are commercially available and can be used in rutile or anatase type. Such Rutile-type titanium dioxides are particularly preferred.

Other fillers such as zinc sulfide, Calcium carbonate, kaolin or mixtures thereof are used become.

The proportion of the filler in the decorative base paper can be up to 55% by weight, in particular 11 to 50% by weight or 20 to 45% by weight, based on the weight of the paper. The basis weight of the decorative base papers according to the invention can be in the range from 30 to 300 g / m ² and will usually be 40 to 200 g / m ² . The basis weights are selected depending on the particular application.

As cellulose for the production of the invention Decorative base papers can be softwood pulp (long fiber Pulp) or hardwood pulp (short fiber Cellulose) can be used. The use of Cotton fibers or mixtures of the aforementioned Types of pulp can be used. Especially a mixture of, for example, is preferred Softwood / hardwood pulps in a ratio of 10: 90 to 90:10 or, for example, mixtures of softwood / Hardwood pulp in a ratio of 30: 70 to 70: 30 Pulp can have a freeness of 20 ° to 60 ° SR Have Schopper-Riegler.

The pulp mixture preferably contains a proportion of cationically modified cellulose fibers of at least 5 wt .-%, based on the weight of the pulp mixture. A portion has proven to be particularly advantageous from 10 to 50% by weight, in particular 10 to 20% by weight of the cationically modified pulp in the pulp mixture proved.

Cationically modified pulps are for example from DAS PAPIER, No. 12 (1980) pp. 575-579.

In a special embodiment of the invention, the cationically modified contained in the pulp Pulp an effective cationic charge of 20 to  300 mmol / kg pulp, determined according to the internal Method No. 4 of the TU Darmstadt. To be favoured Pulp fibers with a charge density of 30 to 200 mmol / kg, in particular 30 to 100 mmol / kg. Under the The term "effective cationic charge" is one To understand charge density, which corresponds to the charge density of the not cationized pulp was charged. The Charge density of the pulp depends on the amount of cationic agent to be used. The amount of cationizing agent can be 0.005 to 200 g / l kg Amount of pulp.

The cationic modification of the pulp fibers can by reaction of the fibers with epichlorohydrin resin and take place with a tertiary amine or by reaction with quaternary ammonium chlorides, such as Chlorhydroxypropyltrimethyl ammonium chloride or Glycidyltrimethyl ammonium chloride.

In a preferred embodiment of the invention Pulp fibers used by a Addition reaction of quaternary, glycidyl-functional Groups containing ammonium compounds with Hydroxyl groups of cellulose modified cationically are.

The decorative base paper according to the invention can wet strength agents such as polyamide / polyamine-epichlorohydrin resin, others Polyamine derivatives or polyamide derivatives, cationic Polyacrylate, modified melamine-formaladehyde resin or contain cationized starches. These will be the Cellulose suspension added. The addition of Retention aids and other substances such as  organic and inorganic colored pigments, dyes, optical brightener and dispersant possible.

The decorative base papers according to the invention can be on a Fourdrinier paper machine or a Yankee Paper machine. This can be done Pulp mixture with a consistency of 2 to 4% by weight be ground to a freeness of 30 to 45 ° SR. Fillers such as titanium dioxide are used in a mixing chest and talc, and wet strength additive and with the Cellulose mixture well mixed. The so obtained Thickness is up to a consistency of about 1 wt .-% diluted and, if necessary, other auxiliaries such as Retention aids, defoamers, aluminum sulfate and others admixed aforementioned additives. This thin substance is placed on the headbox of the paper machine Screen section led. A nonwoven fabric is formed and receive the decorative base paper after drainage, which is then dried.

For the production of decor papers, the Decorative base papers with the usual for this purpose Impregnated or impregnated synthetic resin dispersions. For this purpose are conventional synthetic resin dispersions for example those based on polyacrylic or Polyacrylic methyl esters, polyvinyl acetate, polyvinyl chloride or synthetic resin solutions based on phenol / formaldehyde, Urea / formaldehyde or melamine / formaldehyde Pre-condensates or their compatible mixtures.

The impregnation can also be done in the size press Paper machine done. The decorative base paper can be such be impregnated that the paper is not complete  is impregnated by. Such decorative papers are also known as pre-impregnates. The share of that in that Decorative base paper by impregnation of the resin in this case is 25 to 30 wt .-%, based on the Weight of the paper.

After drying, the soaked papers can still painted and printed and then on a Substrate can be applied like a wooden plate. The painted and possibly printed products generally referred to as decorative films.

The following examples are provided for further explanation the invention. Figures in percent by weight refer on the weight of the pulp, unless otherwise is specified.

example 1

A cellulose mixture of 70% by weight was used as the basic mixture. Eucalyptus pulp and 30% by weight softwood sulfate pulp with 0.6% by weight epichlorohydrin resin as wet strength agent, 0.11% by weight a retention aid and 0.03% by weight of one Defoamer, the latter three components each related to the mass of the pulp mixture. The Mixture was adjusted to pH with aluminum sulfate 6.5 set.

A pigment mixture of 55.8% by weight of titanium dioxide and 5.2% by weight of talc was added to this mixture. A decorative paper with a weight per unit area of 105 g / m ^{2 was} produced using a Fourdrinier paper machine. The titanium dioxide content was 33.5 g / m ² (31.9% by weight) and the talc content 3.1 g / m ² (2.95% by weight). The talc had a grain size distribution D50 of 1.9 µm and a specific surface area of 44,300 m ² / kg.

Example 2

A was added to the basic mixture from Example 1 Pigment mixture of 50.3% by weight of titanium dioxide and 14.7% by weight Given talc.

A decorative paper with a weight per unit area of 105 g / m ^{2 was} produced using a Fourdrinier paper machine. The titanium dioxide content was 30.2 g / m ² (28.8% by weight) and the talc content 8.8 g / m ² (8.4% by weight). The talc had a grain size distribution D50 of 1.9 µm and a specific surface area of 44,300 m ² / kg.

Example 3

A pigment mixture of 64.5% by weight of titanium dioxide and 3.3% by weight of talc was added to the basic mixture from Example 1. A decorative paper with a weight per unit area of 105 g / m ^{2 was} produced using a Fourdrinier paper machine. The titanium dioxide content was 38.7 g / m ² (36.5% by weight) and the talc content was 2.0 g / m ² (1.9% by weight). The talc had a grain size distribution D50 of 1.9 µm and a specific surface area of 44,300 m ² / kg.

Example 4

A pigment mixture of 53.9% by weight of titanium dioxide and 11.3% by weight of talc was added to the basic mixture from Example 1. A decorative paper with a weight per unit area of 105 g / m ^{2 was} produced using a Fourdrinier paper machine. The titanium dioxide content was 32.3 g / m ² (30.8% by weight) and the talc content was 6.8 g / m ² (6.5% by weight). The talc had a grain size distribution D50 of 1.5 µm and a specific surface area of 47,100 m ² / kg.

Comparative Example 1

As a comparative example 1, only a 62% by weight titanium dioxide dispersion was added to the base mixture from example 1. With a Fourdrinier paper machine, a decorative paper with a basis weight of 120 g / m ² and a titanium dioxide content of 37.2 g / m ² (31% by weight) was produced.

Comparative Example 2

A pigment mixture of 50.8% by weight of titanium dioxide and 14.4% by weight of talc was added to the basic mixture from Example 1. A decorative paper with a weight per unit area of 105 g / m ^{2 was} produced using a Fourdrinier paper machine. The titanium dioxide content was 30.5 g / m ² (29% by weight) and the talc content was 8.7 g / m ² (8.3% by weight). The talc had a grain size distribution D50 of 3.7 µm and a specific surface area of 8,600 m ² / kg.

On paper samples from Examples B1 to B4 and Comparative examples V1 and V2 became the opacity with an ACE color measuring device from Data Color according to DIN 53146 certainly. The titanium dioxide content in the decorative base paper was determined according to DIN 54370. The results obtained are shown in the table.

The results of the opacity measurement show that with the Talc used according to the invention has a high opacity even with a significantly reduced proportion of titanium dioxide can be achieved.

Claims (6)

1. Decorative base paper for decorative coating materials, characterized in that the decorative base paper contains a pigment mixture of titanium dioxide and talc and the talc has a grain size distribution D50 of less than about 3.0 microns. 2. decorative base paper according to claim 1, characterized in that the talc has a specific surface area of greater than about 30,000 m ² / kg. 3. Decorative base paper according to claim 1 or 2, characterized characterized in that the talcum content is 0.1 to 25% by weight, based on the total pigment content. 4. decorative base paper according to one of claims 1 to 3, characterized in that the paper is cationic contains modified cellulose fibers. 5. decorative base paper according to claim 4, characterized characterized in that the pulp fibers with quaternary Modified ammonium compounds with glycidyl function are. 6. Decorative paper or decorative film containing one Decorative base paper according to one of claims 1 to 5.