Claims:WE CLAIM:
1. A decorative laminate sheet comprising:
- an opaque paper substrate having an operative top surface;
- a layer of a water based ink composition printed in a pre-determined pattern/arrangement, by ink jet printing on said operative top surface of said opaque paper substrate;
- a clear, glossy, heat resistant, and water based melamine resin coating on top of the printed pattern/arrangement; and
- a phenolic resin impregnated prepreg at an operative bottom surface of said decorative laminate sheet,
wherein said melamine resin coating forms the operative top surface of said decorative laminate sheet.
2. The decorative laminate sheet as claimed in claim 1, wherein said opaque paper substrate is loaded with titanium oxide.
3. The decorative laminate sheet as claimed in claim 1, wherein said water based ink composition is selected from reactive dye based composition and disperse dye based composition.
4. The decorative laminate sheet as claimed in claim 3, wherein the surface tension of said reactive dye based composition is in the range of 34 to 38 mN/m and the surface tension of said disperse dye based composition is in the range of 30 to 38 mN/m.

5. The decorative laminate sheet as claimed in claim 1, wherein said reactive dye is selected from the group consisting of C.I.reactive blue-72, C.I. reactive blue-49, C.I.reactive yellow- 95, C.I.reactive red-24, C.I.reactive red-218, C.I.reactive red-245, C.I.reactive black-39, C.I.reactive brown-11 and C.I.reactive orange-12, and C.I.reactive orange-13.
6. The decorative laminate sheet as claimed in claim 1, wherein said disperse dye is selected from the group consisting of C.I.disperse yellow-54, C.I.disperse yellow-114, C.I.disperse blue-60, C.I.disperse red-60, C.I.disperse red-13, C.I.disperse red-50 and C.I.disperse black mixed dyes.
7. The decorative laminate sheet as claimed in claim 1, wherein said water based ink composition further comprises acrylic dispersions and surfactant.
8. The decorative laminate sheet as claimed in claim 7, wherein said surfactant is selected from the group consisting of diethanolamines (DEAs), Alkyl sulfonates, alkyl aryl sulfonates, ethoxylates, Surfynol 465, Surfynol-440, , non-ionic surfactants and alcohol ethoxylates.
9. The decorative laminate sheet as claimed in claim 1, wherein the particle size of said dye based composition is in the range of 0.01 µm to 1.5 µm.
10. A process for preparing a decorative laminate sheet, said process comprising the following steps:
a. homogenizing a water based ink composition at a pre-determined speed of agitation and pre-determined time period to form a slurry;
b. printing said slurry on the operative top surface of an opaque paper substrate in a pre-determined pattern/arrangement, using ink jet printing method to obtain a printed paper substrate;
c. coating a clear, glossy, heat resistant, and water based melamine resin on said printed paper substrate to obtain a decorative impregnated prepreg material; wherein said decorative impregnated prepreg material is in the form of roll or sheet,
d. disposing a phenolic resin impregnated prepreg on an operative bottom surface of said decorative impregnated prepreg material to obtain a pack; and
e. laminating said pack to obtain said decorative laminate sheet.
11. The process as claimed in claim 10, wherein said printed paper substrate obtained in process step (b) is dried prior to coating with said melamine resin.
, Description:FIELD
The present disclosure relates to decorative laminate sheets and a process for preparing the same.
DEFINITIONS
As used in the present disclosure, the following terms are generally intended to have the meaning as set forth below, except to the extent that the context in which they are used indicate otherwise.
Decorative laminate sheet: The term “decorative laminate sheet” refers to laminate consisting of a single or multiple layers, each having its own distinct function.
Grams per Square Meter (GSM): The term refers to the weight of a paper sheet. Higher the GSM number, the heavier is the paper.
Prepreg: The term “prepreg” refers to a reinforcing fabric which has been pre-impregnated with a resin system. This resin system (typically epoxy) already includes a proper curing agent. As a result, the prepreg is ready to be laid into a mold without the addition of further resin. The laminate can be cured by a combination of pressure and heat.
Platen: The term “platen” also known as platen refers to a flat platform made of flat metal or wood, which is pressed against a medium (such as paper) to cause an impression in letterpress printing.
BACKGROUND
The background information herein below relates to the present disclosure but is not necessarily prior art.
Decorative laminates are used as surfacing materials, where attractive aesthetic effects are desired along with the functional behaviors, such as abrasion resistance, resistance to heat and burning, and resistance to stain by food, coffee, tea, various solvents, and chemicals, resulting in a simple maintenance and long life. The decorative laminates are widely used for a variety of interior surfaces, both horizontal and vertical, as well as furnishing in private and commercial constructions. Typical applications are in tables, counters, sink boards, doors, walls, office partition, and other building exterior and interior application.
Decorative Paper laminates are obtained by bonding decorative papers over a variety of substrates. Decorative Paper laminates find numerous applications, primarily due to the availability of decorative paper in a variety of print patterns and colors. Typically, thermosetting resin, such as melamine formaldehyde and urea formaldehyde, are used for impregnation and partially cured for making prepreg sheets, which are used as a top surface along with phenolic resin impregnated Kraft paper prepreg sheets as a backup, to provide mechanical strength to the laminates. These assembled sheets (generally 8ft x 4ft size) / with gloss or matt /satin finish are placed on top of the decorative laminate sheet to provide the desired finish to the decorative laminate, and these packs are then placed between the openings/exposed layers of the press platens. These openings/exposed layers are closed and pressure is applied by hydraulic system over the area of the sheets being laminated and then it is heated by steam, oil, or hot water that is introduced into the channels within the individual press platens. After curing, steam is drained out and simultaneously platens are cooled with running chilled water. Once the laminated sheet are cooled, pressure is released and the press is opened and the laminated sheet is transferred to a conveyer and then further processed by for trimming, sanding (phenolic core side) and QA inspection / Testing before being dispatched to the market.
Conventionally, rotogravure printing process is used for printing images on the specialized opaque papers (TiO2 loaded) rolls to obtain the decorative paper. In rotogravure printing, the image is engraved onto a cylinder and it uses a rotary printing press. However, each design requires about 3 to 4 cylinders, which considerably increases the overall cost, and restricts the number of designs that can be printed. Further, large amount of space is required for storing the cylinders having different designs, which is not economically feasible. Moreover, the laminate manufacturers can import the printed rolls based on their choice / market demand. Generally, the designs become outdated and become dead stock or non-moving stock which has to be disposed as scrap, resulting in significant economic loss.
Therefore, due to the large demand of paper laminates in furniture, residential and commercial installations, and industrial applications, there is felt a need for a process for preparing decorative paper laminate sheets that mitigates the hereinabove mentioned drawbacks.
OBJECTS
Some of the objects of the present disclosure, which at least one embodiment herein satisfies, are as follows.
It is an object of the present disclosure to ameliorate one or more problems of the prior art or to at least provide a useful alternative.
Another object of the present disclosure is to provide decorative laminate sheets.
Still another object of the present disclosure is to provide a process for preparing decorative laminate sheets.
Other objects and advantages of the present disclosure will be more apparent from the following description, which is not intended to limit the scope of the present disclosure.
SUMMARY
The present disclosure relates to a decorative laminate sheet and a process for preparing the decorative laminate sheet. In an aspect, the decorative laminate sheet comprises an opaque paper substrate having an operative top surface; a layer of a water based ink composition printed in a pre-determined pattern/arrangement by ink jet printing on the operative top surface of the opaque paper substrate; a clear, glossy, heat resistant, and water based melamine resin coating on top of the printed pattern/arrangement; and a phenolic resin impregnated prepreg at an operative bottom surface of the decorative laminate sheet. The melamine resin coating forms the operative top surface of the decorative laminate sheet.
In another aspect, the process for preparing a decorative laminate sheet comprises homogenizing water based ink composition at a pre-determined speed of agitation and at a pre-determined time period to form slurry. The slurry is printed on the operative top surface of an opaque paper substrate in a pre-determined pattern/arrangement using ink jet printing method to obtain a printed paper substrate. A clear, glossy, heat resistant, and water based melamine resin is coated on the printed paper substrate to obtain a decorative impregnated prepreg material; wherein the decorative impregnated prepreg material is in the form of roll or sheet. A phenolic resin impregnated prepreg is disposed on an operative bottom surface of the decorative impregnated prepreg material to obtain a pack; and laminating the pack to obtain the decorative laminate sheet.
DETAILED DESCRIPTION
Embodiments are provided so as to thoroughly and fully convey the scope of the present disclosure to the person skilled in the art. Numerous details are set forth, relating to specific components, and methods, to provide a complete understanding of embodiments of the present disclosure. It will be apparent to the person skilled in the art that the details provided in the embodiments should not be construed to limit the scope of the present disclosure. In some embodiments, known processes or well-known apparatus or structures, and well known techniques are not described in detail.
The terminology used, in the present disclosure, is only for the purpose of explaining a particular embodiment and such terminology shall not be considered to limit the scope of the present disclosure. As used in the present disclosure, the forms "a,” "an," and "the" may be intended to include the plural forms as well, unless the context clearly suggests otherwise. The terms "comprises," "comprising," “including,” and “having,” are open ended transitional phrases and therefore specify the presence of stated features, integers, steps, operations, elements, modules, units and/or components, but do not forbid the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The particular order of steps disclosed in the method and process of the present disclosure are not to be construed as necessarily requiring their performance as described or illustrated. It is also to be understood that additional or alternative steps may be employed.
The terms first, second, third, etc., should not be construed to limit the scope of the present disclosure as the aforementioned terms may be only used to distinguish one element, component, region, layer or section from another component, region, layer or section. Terms such as first, second, third, etc., when used herein do not imply a specific sequence or order unless clearly suggested by the present disclosure.
The present disclosure envisages decorative laminate sheets that are prepared by ink jet printing technique. Water based, heat resistant ink composition is printed on a paper substrate by ink jet printing. The present disclosure provides a process for preparing decorative laminate sheets which can be customized as per the customer requirement or the market demand/trend. Further, the process of the present disclosure will aid in achieving zero inventory of the printed stock.
In an aspect of the present disclosure, there is provided a decorative laminate sheet. The decorative laminate sheet comprises an opaque paper substrate having an operative top surface, a layer of water based ink composition printed in a pre-determined pattern/arrangement, by ink jet printing on the operative top surface of the opaque paper substrate, a coating of clear, glossy, heat resistant, and water based melamine based resin over the printed pattern/arrangement (decorative impregnated prepreg material), and a phenolic resin impregnated prepreg as an operative bottom surface of the decorative laminate sheet. The coating of clear, glossy, heat resistant, and water based melamine based resin over printed pattern/arrangement is the operative top surface of the decorative laminate sheet.
The opaque paper substrate is typically loaded with titanium oxide.
The water based ink composition used in the preparation of decorative laminate sheets is selected from reactive dye based composition and disperses dye based composition.
The surface tension of the reactive dye based composition is in the range of 34 to 38 mN/m and the surface tension of the disperse dye based composition is in the range of 30 to 38 mN/m.

The reactive dye based composition is selected from the group consisting of C.I.reactive blue-72, C.I. reactive blue-49, C.I.reactive yellow- 95, C.I.reactive red-24, C.I.reactive red-218, C.I.reactive red-245, C.I.reactive black-39, C.I.reactive brown-11 and C.I.reactive orange-12, and C.I.reactive orange-13.
The disperse dye based composition is selected from the group consisting of C.I.disperse yellow -54, C.I.disperse yellow-114, C.I.disperse blue-60, C.I.disperse red-60, C.I.disperse red-13, C.I.disperse red-50 and C.I.disperse black mixed dye.
The particle size of the dye based composition is in the range of 0.01µm to 1.5µm. The viscosity of the ink composition can be in the range of 3 cps to 7 cps. The ink composition of the present disclosure is resistant to temperatures up to 170 °C, tested as per the IS 2046 standard. Due to the temperature resistance, the applied color does not bleed or fade over time.
In an embodiment, the ink composition of the present disclosure may be used to print a pattern/design/image/text on a substrate. In a preferred embodiment, the substrate is paper typically, an opaque paper that is loaded with titanium oxide (TiO2). Titanium oxide provides opacity to the paper substrate. Typically, the weight of the paper substrate can be in the range of 80 GSM to 100 GSM.
The water based ink composition used in the decorative laminate sheets of the present disclosure further comprises acrylic resin and surfactant. The surfactant is selected from the group consisting of diethanolamines (DEAs), Alkyl sulfonates, alkyl aryl sulfonates, ethoxylates, non-ionic surfactants (SURFYNOL series), and alcohol ethoxylates. In an exemplary embodiment of the present disclosure, surfynol-440 and surfynol-465 are used as surfactants in the ink composition.
In another aspect of the present disclosure, there is provided a process for preparing the decorative laminate sheets. The process comprises printing a water based ink composition on the operative top surface of an opaque paper substrate in a pre-determined pattern/arrangement, using ink jet printing to obtain a printed paper substrate. A clear, glossy, heat resistant, and water based melamine resin is coated on the printed paper substrate to obtain a decorative impregnated prepreg material. A phenolic resin impregnated prepreg is disposed on an operative bottom surface of the decorative impregnated prepeg material to obtain a pack; and laminating the pack to obtain the decorative laminate sheet of the present disclosure.
Typically, the printed paper substrate is dried at a pre-determined temperature for a pre-determined time period to obtain a dried paper substrate; prior to coating with the melamine resin.
The decorative impregnated prepreg material is typically in the form of a roll or a sheet.
In an embodiment, the printed paper substrate is passed through a dryer to remove excess water. This allows the pigments present in the ink composition to settle onto the surface of the opaque paper substrate.
In an embodiment of the present disclosure, the dried opaque printed paper substrate is impregnated with a melamine formaldehyde based resin system using well known impregnation techniques. After the opaque paper substrate is impregnated with the melamine formaldehyde based resin system, it is dried and then cut into pre-determined size and pasted on a core, followed by application of pressure to obtain the decorative laminate sheet of the present disclosure. Any known technique can be used to apply pressure.
The decorative laminate sheet of the present disclosure has resistance to surface wear = 350 pass, resistance to immersion in boiling water of degree 5, resistance to dry heat at 180 oC of degree 5, resistance to steam test of rating 5, resistance to colour change in xenon arc light of degree 5 as per IS 2046:1995 test method.
The foregoing description of the embodiments has been provided for purposes of illustration and not intended to limit the scope of the present disclosure. Individual components of a particular embodiment are generally not limited to that particular embodiment, but, are interchangeable. Such variations are not to be regarded as a departure from the present disclosure, and all such modifications are considered to be within the scope of the present disclosure.
The present disclosure is further described in light of the following experiments which are set forth for illustration purpose only and not to be construed for limiting the scope of the disclosure. The following experiments can be scaled up to industrial/commercial scale and the results obtained can be extrapolated to industrial scale.
EXPERIMENTAL DETAILS:
Experiment-1: Decorative laminate in accordance with the present disclosure
Decorative laminate sheet was prepared by printing the homogenized water based ink composition slurry on the operative top surface of an opaque paper substrate by using ink jet printing method to obtain a printed paper substrate. A clear, glossy, heat resistant, and water based melamine resin were coated on the printed paper substrate to obtain a decorative impregnated prepreg material. The decorative impregnated prepreg material is in the form of roll or sheet. A phenolic resin impregnated prepreg as an operative bottom surface is disposed on an operative bottom surface of the decorative impregnated prepeg material to obtain a pack; and laminating the pack to obtain said decorative laminate sheet.
The details regarding the water based ink composition slurry, paper substrate, and water based melamine resin was given in Table 1 below:
Table 1: Details of the components
Sr. No
Key components
Reactive dye
Disperse Dye

Ink system Water base Water base
Dye
CI number Dye
1. Reactive blue- 72, 49
2. Reactive yellow- 95
3. Reactive red- 24, 218, 245
4. Reactive black- 39
5. Reactive brown- 11
6. Reactive orange- 12, 13 Dye
1. Disperse yellow- 54, 114
2. disperse blue- 60
3. disperse red- 60, 13, 50
4. disperse Black mixed dyes

Resin/ Dispersant
system Acrylic dispersion Acrylic dispersion
Surface tension 34-38 mN/m 30-38 mN/m
Surfactants SURFYNOL -465, SURFYNOL -440 SURFYNOL- 465
Paper Substrate
Paper substrate Tecnocell Tecnocell
Paper size 80 GSM 80 GSM
Ash contain 20-25% TiO2 20-25% TiO2
Machine specification
Machine model Vibrant 1800 Indian textile engineer
Print head Sapphire 256
10 PL
Fujifilm Dimatix

1. Star fire 1024-1C,
400 DPI
2. Star fire 1024-2C
200 DPI
12 PL
Fujifilm Dimatix
Number of pass 10/14/22/28 Pass 2/4 Pass
Printability Print quality is ok Print quality is ok

The so obtained decorative laminates having improved properties such as resistance to surface wear, resistance to immersion in boiling water, resistance to dry heat at 180 oC and resistance to color change in Xenon arc light. The results are summarized.
Table 2- Laminate properties
Key components Remark
Reactive
dye Disperse
Dye
Resistance to surface wear = 350 Pass
(As per IS 2046:1995) = 350 Pass
(As per IS 2046:1995)
Resistance to immersion
in boiling water Degree 5
(As per IS 2046:1995) Degree 5
(As per IS 2046:1995)
Resistance to dry heat at 180 oC Degree 5
(As per IS 2046:1995) Degree 5
(As per IS 2046:1995)
Resistance to steam test Rating 5
(As per IS 2046:1995) Rating 5
(As per IS 2046:1995)
Resistance to colour
Change in xenon arc light Degree 5
(As per IS 2046:1995) Degree 5
(As per IS 2046:1995)
High resistance to surface wear
High resistance to impact
High resistance to scratching Type- S, F and P for all
Index no-3 for all
(clause 4 as per IS 2046:1995) Type- S, F and P for all
Index no-3 for all
(clause 4 as per IS 2046:1995)

*Laminate properties are checked by IS 2046:1995 standard method.
* = 350 Pass: Initial Wear Point (IP) + Final Wear Point (FP) + Number of Revolutions =350 Pass (Kindly refer Index Number 3 mentioned in Clause 4.1 of IS 2046:1995)
*degree 5: Resistance to immersion in boiling water- degree 5 no visible change
*degree 5: Resistance to dry heat at 180 oC- Degree 5 no visible change
*Rating 5: Resistance to steam test- Rating 5 no visible change
*Type- S, F and P for all Index no-3 for all (clause 4 as per IS 2046:1995)

As summarized in Table 2, the decorative laminate sheet of the present disclosure has passed the test as per IS 2046:1995 which shows resistance to surface wear, resistance to immersion in boiling water, resistance to dry heat at 180 oC and resistance to color change in Xenon arc light.
TECHNICAL ADVANCES AND ECONOMICAL SIGNIFICANCE
The present disclosure described herein above has several technical advantages including, but not limited to, the realization of decorative laminate sheets prepared using water based heat resistant ink composition by ink jet printing. The decorative laminate sheets exhibit resistance to color bleeding and color fading. Multiple cylinders are not required for preparing the decorative laminate sheets of the present disclosure, thus avoiding the issue of storage space and making the overall process cost effective.
The foregoing description of the specific embodiments fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.
Throughout this specification the word “comprise”, or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.
The use of the expression “at least” or “at least one” suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the disclosure to achieve one or more of the desired objects or results.
Any discussion of documents, acts, materials, devices, articles or the like that has been included in this specification is solely for the purpose of providing a context for the disclosure. It is not to be taken as an admission that any or all of these matters form a part of the prior art base or were common general knowledge in the field relevant to the disclosure as it existed anywhere before the priority date of this application.
The numerical values mentioned for the various physical parameters, dimensions or quantities are only approximations and it is envisaged that the values ten percent higher/lower than the numerical values assigned to the parameters, dimensions or quantities fall within the scope of the disclosure, unless there is a statement in the specification specific to the contrary.
While considerable emphasis has been placed herein on the components and component parts of the preferred embodiments, it will be appreciated that many embodiments can be made and that many changes can be made in the preferred embodiments without departing from the principles of the disclosure. These and other changes in the preferred embodiment as well as other embodiments of the disclosure will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the disclosure and not as a limitation.