GB2319989A

GB2319989A - Coated decorative sheet

Info

Publication number: GB2319989A
Application number: GB9725454A
Authority: GB
Inventors: Jean-Claude Capra
Original assignee: Solvay SA
Current assignee: Solvay SA
Priority date: 1996-12-06
Filing date: 1997-12-01
Publication date: 1998-06-10
Anticipated expiration: 2017-12-01
Also published as: BE1011391A3; ITMI972635A1; GB9725454D0; NL1007635C2; ES2141031B1; FR2756851B1; DE19753482A1; NL1007635A1; FR2756851A1; ES2141031A1; GB2319989B; IT1296575B1

Abstract

Decorative sheet which includes a substrate of fabric (T) to which is applied at least one coating layer (C) based on a plastic composed of at least one vinyl chloride polymer, being characterized in that the coating layer (C) is provided with a surface embossment reproducing the relief on a fabric (G). Preferably, the fabric (G) serving as a pattern for the embossment has a structure substantially different from that of the fabric (T).

Description

2319989 Coated decorative sheet and process for its manufacture The

present invention relates to a decorative sheet which includes a layer of fabric and at least one plastic coating layer, and a process for its manufacture.

Many consumer articles, such as table linen, American cloth, etc. consist of plastic-coated fabric.

However, in order to give these articles a pleasing visual appearance and a pleasant feel, approaching closer to those of a fabric than those of a plastic sheet, a great deal of attention must be paid to their surface finish. When certain plastics are used to coat a fabric, for example acrylic polymers, a good surface finish may be obtained but at the cost of special pre- treatments (the use of substances rendering the fabric hydrophobic, is calendering the fabric before it is coated, etc.). Furthermore, acrylic polymers are expensive and the mechanical properties of the articles thus obtained alter after machine washing at 400C, which is disadvantageous. This is why manufacturers of this type of article prefer 20 to use standard and inexpensive polymers such as, for example, vinyl chloride polymers, and in particular polyvinyl chloride (PVC). When PVC is used to coat a fabric, the sheet of plastic-coated fabric thus obtained is generally smooth and shiny. For applications such as 25 table linen, it is desirable to improve the appearance of this type of sheet; to do this, one simple solution consists in embossing the surface of the plastic coating layer, i.e. giving it a slight roughness. If the embossment is very fine and random, it is thus possible 30 to obtain sheets which are less shiny, but which remain relatively smooth. The latter disadvantage may be avoided by embossing them with a more pronounced relief; however, irregular embossing does not always lead to a satisfactory result. This is why one object of the present 35 invention is to provide a decorative sheet based on a fabric and a vinyl chloride polymer having a pleasing visual appearance and a pleasant feel. Another object of the invention is to provide a simple process allowing 2 such sheets to be manufactured.

To this end, the present invention relates to a decorative sheet which includes a substrate of fabric (T) to which is applied at least one coating layer (C) based on a plastic composed of at least one vinyl chloride polymer, which is characterized in that the coating layer (C) is provided with a surface embossment reproducing the relief on a fabric (G).

However, one problem which may arise with such a decorative sheet is the moir6 effect, i.e. visual interference which the superposition of the weft yarns of the substrate fabric and of the embossment may cause.

To this end, in an advantageous variant of the present invention, the fabric (G) serving as a pattern is for the embossment has a structure substantially differ ent from that of the fabric (T).

The substrate of fabric (T) comprises a woven fabric, i.e. a fabric having a well-defined repetitive structure. Conventionally, its structure may be charac- terized by its weave, i.e. by the number of warp yarns (these are the yarns placed along the length of the fabric) and of weft yarns (the yarns placed across the width of the fabric) of which it is composed, and by the diameter of the yarns used, expressed for example as the "metric count", i.e. as the number of kilometres per kilogram of cotton yarn of the same diameter. The fabric used may furthermore be printed with decorative patterns, or it may be uniformly coloured.

The coating layer (C) may be applied to the substrate of fabric (T) by any known method, for example by calendering or by adhesive bonding.

The coating layer (C) may be applied to the substrate of fabric (T) directly, or via one or more other layers of plastic. In order to improve their adhesion, it is advantageous for a tie layer to be interposed between the fabric (T) and the coating layer (C). This tie layer is generally thin and preferably also comprises at least one vinyl polymer. Very good results have been obtained using, as the tie layer, a layer of a plastisol containing PVC and a plasticizer, the plastisol being gelled by raising the temperature after bringing the layers in question into contact with each other.

Advantageously, one or more other, generally thin, layers of plastic, for example a protective varnish, may be deposited on the outside of the coating layer (C), i.e. on the side opposite the layer of fabric (T) (before or after the said coating layer is applied to the fabric).

Preferably, the vinyl chloride polymer of which the coating layer (C) is composed essentially consists of polyvinyl chloride (PVC), which may optionally contain one or more usual additives such as plasticizers, processing aids, pigments, etc. However, in most cases it is is preferable for the layer or all the layers of plastic applied directly or indirectly to the substrate of fabric (T) to be substantially transparent and colourless.

That side of the layer of fabric (T) opposite the one to which the coating layer (C) is applied, which is not generally visible in standard applications, may optionally also be coated with one or more layers of plastic, as required.

The embossing of the coating layer (C) may be carried out using any known method. The most conventional method of embossing a sheet consists in calendering it between a first roll (the,embossing roll"), which is hard (e.g. made of metal) and the surface of which reproduces the negative of the desired embossment, and a second roll (the "counterpart"), at least the surface of which is deformable (e.g. a rubber-coated roll). The embossing roll may in particular be manufactured by knurling or by electroforming. The latter technique is particularly advantageous given that it allows highquality reproduction of the relief on the starting material, even if the latter has slight reverse tapers. In order to produce an embossing roll, reproducing the relief on a fabric (G), by electroforming, the following sequence of steps may, in particular, be applied:

first of all, a negative impression of the fabric is (G) is taken by using a suitable material, such as a silicone-containing mastic, which is polymerized; a soft positive impression is made from this negative impression by means of a suitable material, for example by means of a PVC plastisol which is gelled; this soft positive impression is rolled up so as to form a roll in which the embossed side lies on the inside; this cylindrical positive impression is adhesively bonded to the inside of a rigid roll (for example a steel roll) and a suitable product having a good electrical conductivity is sprayed onto it; this assembly is dipped into one or more electroplating solutions so as to deposit thereon, by electrolysis, a metal layer (e.g. a nickel and/or copper layer) having a sufficient mechanical strength (typical thickness about 1 mm); the soft positive impression and the rigid negative metallic impression thus obtained are extracted from the rigid roll and separated from each other; and the negative metallic impression is fixed to a rigid support (for example a steel arbor) in order to form an embossing roll which can be used in a sheet treatment plant.

One of the main characteristics of the present invention resides in the fact that the fabric (G) serving as a pattern for the embossment has a structure substantially different from that of the substrate fabric (T).

A first way of quantifying the structure of these two fabrics is to characterize them by their weave, i.e. by the number of warp and weft yarns forming their meshwork. If the fabric (G) and the fabric (T) are defined respectively by weaves of MxN and PxQ, a quality criterion for the plastic-coated sheet described above is to impose that both the relative difference between M and P (A(M,PH and the relative difference between N and Q (A(N,Q)) be each at least 1.15. For the purposes of the present invention, the relative difference A(x,y) between two numbers x and y is def ined as being equal to the greater of the two ratios x/y and y/x (this ratio is therefore always a number at least equal to 1). It is particularly preferable that at least one of these relative differences, and if possible both of them, be at least 1.17.

According to an advantageous variant, it is moreover desirable that the two relative differences defined above each differ by at least 0.15 from integers, that is to say that these differences do not lie between 1.85 and 2.15, or between 2.85 and 3.15, etc.

A second way of quantifying the structure of these two fabrics consists in using two parameters X and Y, denoting respectively the number of warp yarns and the number of weft yarns per unit length (for example per mm). These parameters may be easily deduced from a characterization, which is more common, of the form '1AxB CID" (A denoting the number of warp yarns, B the number of weft yarns, and C and D respectively the metric counts of these yarns). Considering on the one hand the fabric (T) to be coated with plastic and on the other hand the fabric (G) used as a pattern for the embossment, the embossed plastic-coated sheet defined above may consequently be characterized by means of the following 4 parameters: Xr, XG (both expressed in the same unit) and YTI Yc; (both expressed in the same unit). If the ratio k. is def ined as being equal to the greater of X,/X,, and XG/XT, and similarly if ky is defined as being equal to the greater of YT/YG and YG/YT, it is advantageous that kx and ky also satisfy the abovementioned conditions for the relative dif f erences A (M, P) and A (N, Q), that is to say that they are. 1.15 and preferably that they differ by at least 0.15 from an integer.

Moreover, apart from a substantial difference in structure between each of them, it is desirable that the fabric (T) and the embossment reproducing the fabric (G) be placed so as to be substantially parallel to each other, any misalignment between them not exceeding 10, or preferably 0.10 (the misalignment is therefore the angle between the warp yarns of the fabric (T) and the warp - 6 yarns of the impression of the f abric (G) which the embossment reproduces).

The present invention also relates to a process for the manufacture of a decorative sheet as described above, in which a fabric (T) is calendered with at least one coating layer (C) based on a plastic composed of at least one vinyl chloride polymer, characterized in that the coating layer (C) is superficially provided with an embossment reproducing the relief on a fabric (G). In particular, the variant as described above, according to which the fabric (G) serving as a pattern for the embossment has a structure substantially different from that of the fabric (T), is in this case also advantageous.

is EXAMPLES

The following examples illustrate the invention in a non-limiting manner. Example 1 is in accordance with the invention; Examples 2R and 3R are given by way of comparison.

A transparent and colourless 100 g/m' (approxi mately 80 pm thick) film of plastisol PVC, obtained by calendering, is coated on one of its sides with approxi mately 3 g/m' of an acrylic varnish by intaglio printing and drying in a ventilated oven. Approximately 25 g/M2 Of a tie layer (approximately 2 pm thick), consisting of a PVC plastisol (PVC + plasticizer), is deposited on the unvarnished side of the PVC film.

That face of the PVC film coated with the tie layer plastisol is brought into contact with the visible side of a cotton fabric, which is printed, with a "cloth" weave. The characteristics of the various fabrics used are given in the table below.

The assembly is applied by rubber-coated pressure rolls against a largediameter heated drum (approx. 14 0 0 C), f or approximately 6 s, in such a way that the fabric is in contact with the drum. Next, the assembly passes between two infraredheated panels in order to gel the tie layer and soften the plastic with a view to embossing. Next, the sheet thus obtained is calendered 7 between, on the one hand, a metal embossing roll, the temperature of which is set at approximately400C, provided with a surface relief using an electroforming process, and, on the other hand, a rubber-coated counter part and is then cooled by passing it over chill rolls.

The pattern on the embossing roll had been obtained by electroforming using a fabric having 32x22 50/40 characteristics, comprising, per unit length, XG = 32 yarns/cm and YG = 22 yarns/cm. No angular shift (misalignment) was introduced between this pattern and the axis of the roll, nor between the axis of the fabric (T) and the axis of the roll.

In Example 1, a fabric having a 27x27 (number of warp and weft yarns) 50/50 (metric count of the warp and weft yarns used) weave, comprising XT = YT = 27 yarns/cm per unit length was used. The appearance of the decor ative sheet thus obtained is highly satisfactory and no moire effect is observed.

In Comparative Examples 2R and 3R, a 30x27 50/50 fabric and a 24x24 34/34 fabric were used, respectively.

In both cases, the sheet obtained had a particularly unattractive moir6 effect.

Example 2R 3R

Embossment 32x22 50/40 (G) (M=32; N=22) Substrate 27x27 50/50 30x27 50/50 24x24 34/34 (T) (P=Q=27) (P=30; Q=27) (P=Q=24) A(m,P) 1.185 1.067 1.333 ----------------------------------- ------------------ ------------A(N,Q) 1.227 1.227 1.091 Result good bad bad In this table, A(x,y) represents the relative difference between x and y, as defined previously.

A "bad" result means the presence of an unacceptable moird effect.

8 -

Claims

1. Decorative sheet which includes a substrate of fabric (T) to which is applied at least one coating layer (C) based on a plastic composed of at least one vinyl chloride polymer, characterized in that the coating layer (C) is provided with a surface embossment reproducing the relief on a fabric (G).

2. Decorative sheet according to Claim 1, in which the fabric (G) serving as a pattern for the embossment has a structure substantially different from that of the fabric (T).

3. Decorative sheet according to one of the preceding claims, in which a tie layer is interposed between the fabric (T) and the coating layer (C).

4. Decorative sheet according to one of the preceding claims, in which the vinyl chloride polymer essentially consists of polyvinyl chloride (PVC).

5. Decorative sheet according to one of the preceding claims, in which the fabric (G) and the fabric (T) are defined respectively by weaves of MxN and PxQ, and both the relative di f f erence between M and P (A (M, P)) and the relative dif f erence between N and Q (A (N, Q)) are each at least 1.15, the relative difference A(x,y) between two numbers x and y being defined as the greater of the two ratios x/y and y/x.

6. Decorative sheet according to the preceding claim, in which the two relative differences A(M,P) and A(N,Q) each differ by at least 0.15 from integers.

7. Decorative sheet according to one of the preced ing claims, in which the fabric (T) and the embossment reproducing the fabric (G) are placed so as to be sub stantially parallel to each other, between them not exceeding 10.

8. Process for manufacturing a decorative sheet according to one of the preceding claims, in which a fabric (T) is calendered with at least one coating layer (C) based on a plastic composed of at least one vinyl chloride polymer, characterized in that the coating layer any misalignment - 9 (C) is superficially provided with an embossment repro ducing the relief on a fabric (G).

9. Process according to the preceding claim, in which the fabric (G) serving as a pattern for the embossment has a structure substantially different from that of the fabric (T).

10. A decorative sheet substantially as hereinbefore described with reference to Example 1.