A composition and a method for printing

Description

[0001] The invention relates to a composition for colour printing on a textile material, said composition comprising a first colour pigment, an aliphatic anionic polyurethane binder and an aliphatic polyisocyanate crosslinking agent, and wherein said composition further comprises an anionic acrylic polymer thickener.

[0002] Such a composition is known from EPA 0 571 867 and used for printing on textile. The known composition enables to well lattice it in the textile material even in a temperature range situated between 80 and 170°C.

[0003] A drawback of the known composition is that the aliphatic polyisocyanate crosslinking agent forms between 12.0 and 21.5 % by weight of the composition. Such a composition has a high reactivity so that it is difficult to use it for on-site printing. Moreover, the known component requires a long time before it has, when applied on the material for printing purpose, dried and cured. Indeed, the known composition needs a period, which could even be more than one day for drying and curing. This time could be shortened by heating the printed material to a temperature above 150° C. For application on a textile material formed by a polypropylene needle punched material such a high temperature is not acceptable as polypropylene starts to soften at temperatures of 120° C. For a textile material formed by a polypropylene needle punched material, the drying temperature needs to stay below 120° C. However, at these temperatures the drying and curing time of several hours is too long, in particular when on-site printing has to be done as it is the case for exhibitions.

[0004] The object of the present invention is to realise a composition and a method for colour printing where the composition has a drying and fixation, which can be realised at a temperature lower than 120° C with a short drying and fixation time, preferably less than 5 minutes.

[0005] For this purpose, a composition according to the invention is characterised in that for colour printing on said textile material, which is formed by a polypropylene needle punched textile material, in particular a polypropylene needle punched carpet, said aliphatic polyisocyanate forms 1 to 3 % by weight of the composition. The use of an aliphatic polyisocyanate with such a concentration enables to obtain a composition where the drying and fixation temperature is below 120° C with an acceptable drying and fixation time. Moreover, with such a composition the reactivity is much lower than the one of the known composition, thereby enabling an on-site printing.

[0006] A first preferred embodiment of a composition according to the present invention is characterised in that said aliphatic anionic polyurethane binder forms 20 to 50 % by weight of the composition. This binder enables a drying and curing time of less than 5 minutes.

[0007] A second preferred embodiment of the composition according to the invention is characterised in that said anionic acrylic polymer thickener forms 1 to 2 % by weight of the composition. The combination of the rheological properties and the used thickener concentration in combination with the polyurethane binder forms a suitable composition for printing purpose. The thus obtained composition has a viscosity, which is such that, when valve jet printing heads are used, distinct droplets can be sprayed.

[0008] A third preferred embodiment of the composition according to the invention is characterised in that said aliphatic anionic polyurethane has a pH situated between 8.5 and 9.5 and forms at least 20 % by weight of the total composition. This composition enables to obtain a good adhesion to the material to be printed as well as a good stability in the presence of electrolytes.

[0009] A fourth preferred embodiment of a composition according to the present invention is characterised in that said aliphatic polyisocyanate is water emulsifying. Such a composition already provides good results within a drying and fixation time of six minutes.

[0010] A fifth preferred embodiment of a composition according to the present invention is characterised in that said anionic acrylic polymer is formed by a mineral oil dispersion thereof and has a pH of 7, said anionic acrylic polymer forms at least 1 % by weight of the total composition. This mineral oil dispersion mixes well with the polyurethane while keeping the viscosity within an acceptable range.

[0011] Preferably said composition comprises a second colour pigment formed by white pigment and forming at least 3 % by weight of the total composition. The first colour pigment determines the colour of the print to be realised, whereas the second colour pigment influences positively the resolution and coverage of the surface of the printed area.

[0012] Preferably said composition comprises an anti-fungicide substance forming at least 1 % by weight of the total composition. The use of an anti-fungicide enables a longer storage period of the composition.

[0013] The invention also relates to a method for colour printing on a polypropylene needle punched textile material wherein use is made of the composition according to the present invention by spraying the composition.

[0014] A preferred embodiment of a method according to the present invention is characterised in that a 3D Corona pre-processing or treatment is applied on said material before application of said composition. The 3D Corona pre-processing or treatment enables to further improve the printing quality as well as the adherence of the composition to the material after printing.

[0015] Another preferred embodiment of the method according to the invention is characterised in that before spraying said composition an upper surface of said textile material is scanned in order to detect flatness irregularities in the textile material applied on the floor, and wherein upon detecting said flatness irregularities a distance between said spraying head and said upper surface is adjusted in order that said distance corresponds to a predetermined value. An accurate printing is thus obtained. Moreover, by adjusting the distance a damaging of the printing heads can be avoided.

[0016] The invention also relates to a device for colour printing on a polypropylene needle punched carpet, characterised in that said device comprises a valve jet spraying head provided for spraying a composition having a viscosity of at least 4000 cP.

[0017] The invention will now be described with more detail with reference to the below examples.

[0018] Polypropylene needle punched textile materials, in particular polypropylene needle punched carpets, are often used for exhibitions or in entrance halls of offices or public buildings. There is a growing tendency to have data printed on such textile material or carpets either for informative purposes or for marketing purposes. In particular at exhibitions, the exhibitors want to give a personal touch to the carpets used at their stand. Printing data on the carpet means here an appropriate solution as it offers a personal and non-expensive manner of applying a logo or the like. This printing must however be realised in a fast, reliable and not too expensive manner. Moreover, since exhibitions last sometimes longer than one week, the printing quality must be of a kind that the printed data is during the whole period in a perfect condition and this notwithstanding the fact that a lot of visitors have been walking over it. In particular when a logo is printed on the carpet, the printed logo must remain in good shape in order to avoid any possible negative effect on the logo and consequently on the company to which the logo belongs.

[0019] Polypropylene has certain properties, which need to be taken into account when developing a composition suitable for colour printing on such a material. Polypropylene needle punched textile materials soften at temperatures of 120° C and melt at temperatures of 160° C. Those materials also have a low surface tension leading to moistening and adhesion problems. Polypropylene needle punched textile materials need in fact to be coloured during the fibre/yarn production, so that when printing is applied after production, care should be taken that such a printing is realised with a sufficient covering capacity.

[0020] In order to take the properties into account of the polypropylene needle punched textile materials, a composition for colour printing on such a material has been developed. The composition comprises, next to the first colour pigments necessary to provide the required colour, three basic components :

1) a polyurethane binder, formed by an aliphatic anionic polyurethane;

2) a thickener formed by an anionic acrylic polymer; and

3) an isocyanate crosslinking agent formed by an aliphatic polyisocyanate.

[0021] The fact that both the polyurethane binder and the thickener are anionic, enables an adequate mixing of both substances as an electro-chemical neutral composition is obtained.

[0022] The aliphatic anionic polyurethane has a pH situated between 8.5 and 9.5, whereas the anionic acrylic polymer is a mineral oil dispersion thereof and has a pH of 7.

[0023] In the composition according to the invention, the different components are applied according to the following ranges :

1) 20 to 50 % by weight of aliphatic anionic polyurethane binder, preferably 30 % by weight;

2) 1 to 2 % by weight of anionic acrylic polymer thickener, preferably 1.5 % by weight; and

3) 1 to 3 % by weight of aliphatic poly-isocyanate crosslinking agent, preferably 1.5 % by weight.

[0024] The range of 1 to 3 % by weight of aliphatic poly-isocyanate is necessary to keep the reactivity of the composition low in such a manner that even when the composition is in contact with the open air for several hours, it remains sprayable. The combination of the rheological properties and the used thickener concentration in combination with the polyurethane binder forms a suitable composition for printing purpose.

[0025] In a preferred embodiment of a composition according to the present invention, the following components were used :

1) Rolflex ZB/7 as polyurethane - Rolflex ZB/7 is manufactured by Lamberti s.p.a. in Italy;

2) Lamprint 1030, also manufactured by Lamberti, as polymer; and

3) Tubicoat FIX ICB Conc as polyisocyanate, manufactured by CHT R. Beitlich GmbH in Germany.

[0026] The aliphatic anionic polyurethane binder provides a good adhesion of the composition to synthetic materials such as polypropylene needle punched textile materials. Moreover, the binder provides a very good stability to the composition, in particular in the presence of electrolytes. The viscosity of the component is at least 4000 cP and preferably situated between 4500 and 5000 cP, in particular 4760 cP for the preferred composition mentioned here before.

[0027] The use of the polyisocyanate as crossliking agent enables to reduce the time and temperature required for drying and polymerisation of the applied composition, after printing. The 1 to 3 % by weight of aliphatic poly-isocyanate enables a drying and curing time, after being applied on the textile material, which is less than 10 minutes even at a temperature of less than 120° C. The used polyisocyanate is formaldehyde-free and comprises nitrogen. The crosslinking agent increases the washing resistance and the rub fastness (dry and wet) of the polymers and is water emulsifying, although not soluble in water.

[0028] Another component, which influences the covering capability of the composition, is the content of the pigments. As already mentioned, the composition comprises a first colour pigment, which determines the colour of the component. This first colour pigment forms for example 1 % by weight of the total composition. Additionally, a second colour pigment formed by white pigment is added to the composition. The second colour pigment forms at least 3 % by weight of the total composition and preferably 5 % by weight. Of course, when the first pigment is already white, the second colour pigment will also be white. By adding this second colour pigment, the viscosity of the composition however increases (in the example of 5 % by weight, the viscosity rose to 8.700 cP). This increase of viscosity does however not affect the printing quality and performance as it is still within an acceptable range for spray printing techniques. As will be described hereinafter, the addition of a second colour pigment increases the covering capacity of the print.

[0029] Preferably the composition according to the invention comprises an anti-fungicide and/or an anti-microbial substance forming at least 1% by weight of the total composition. This enables a longer storage period of the composition.

[0030] The invention also relates to a method for colour printing on a polypropylene needle punched textile material wherein use is made of the composition according to the invention. The composition is applied via spray printing techniques, which require a viscosity situated between 4,000 and 15,000 cP, preferably between 4,500 and 5,000 cP. At higher viscosities than 15,000 cP, a too high pressure has to be applied in order to spray the composition. Preferably, a 3D Corona pre-processing/treatment is applied on the material before application of the composition. Indeed, the lack of functional groups within the colour pigments adversely affects the adhesion of the composition to the polypropylene material. The pre-processing with a 3D Corona improves this adhesion.

[0031] The composition is sprayed by using preferably a valve jet technology wherein a spraying pressure of at least one bar is used. The printing is realised by using a printing device, which is mounted in a printing machine mounted on wheels. This enables to move the printing machine over a floor on which the carpet to be printed is applied and to print a logo or any other pattern on the carpet already applied on the floor.

[0032] In order to print a pattern or a logo on the carpet, the printing machine is moved towards the place where the print has to be applied. The printing machine is immobilised at the place where the printing has to be applied. Before spraying the composition on the carpet or textile material, an upper surface of said textile material is scanned in order to detect flatness irregularities in the textile material applied on the floor, which irregularities are often due to an unequal floor on which the carpet is applied. For this purpose the printing device comprises scanning means provided for scanning an upper surface of said textile material in order to detect flatness irregularities in the carpet when applied on a floor. The scanning means are for example formed by a laser or an ultrasonic scanner. The scanning means measures for example the distance between them and the upper surface of the carpet. The scanning means are further provided for adjusting, upon detecting of flatness irregularities, the distance between the spraying head and the upper surface of the carpet in order that said distance corresponds to a predetermined value. Based on the measured distance and knowing the predetermined distance, which is preferably situated between 0.3 and 0.7 cm, the height of the printing head can be adjusted. For this purpose the printing head is preferably movably mounted on a rail and driven by a motor. In such a manner an impact of the printing head on the carpet is avoided, as such an impact could damage the printing head. Moreover, the printing quality is also much better when the distance between the spraying head and the carpet upper surface is kept constant.

[0033] After pre-treatment with the 3D Corona effect, the printing head is moved over the area to be printed in order to apply the component. Thereafter the printing head is moved back to a parking zone within the printing device, where the printing head is preferably subjected to a cleaning operation in order to avoid that the composition would obstruct the printing head. A drying and curing of the composition is realised after printing.

[0034] Different printing tests have been realised in order to measure the performance of the composition. This measurement was realised by testing the dry and wet rub fastness. Such a rub fastness is measured by having a human finger like system wrapped in a standard cotton cloth rubbing 10 times over the printing surface and evaluate the printing quality thereafter and the coloration of the white cloth is evaluated. The rubbing is done once with a dry cotton cloth to evaluate the dry rub fastness and once with a wet cotton cloth, to evaluate the wet rub fastness. The allocated values range between 1 and 5 where 1 indicates a bad rub fastness and 5 a good result. The tests were performed with and without 3D Corona pre-treatment. The applied pressure of the spray printing is also indicated.

[0035] Table 1 shows the results obtained with a composition not having the polyisocyanate.

Table 1

Without corona		With 3D Corona
1 bar
Dry rub fastness	Wet rub fastness	Dry rub fastness	Wet rub fastness
4/5	3	4/5	3

1.5 bar
4/5	3	4/5	3/4

2 bar
4/5	2/3	4/5	3

[0036] The test results shown in table 1 were obtained for a printing, which dried during 5 minutes at 100° C, followed by a fixation and curing time of 10 minutes. As can be seen in the table, the results are acceptable for the dry rub fastness but less acceptable for the wet rub fastness. Moreover, a total time (drying + fixation) of 15 minutes is considered as being long.

[0037] Table 2 shows the results obtained with a composition according to the invention

Table 2

Without corona		With 3D Corona
1 bar
Dry rub fastness	Wet rub fastness	Dry rub fastness	Wet rub fastness
4/5	3	4/5	3

1.5 bar
4/5	3	4/5	3/4

1.75 bar
4/5	3	4/5	3

[0038] As can be seen in this table 2, the results for the wet rub fastness increased. The results were obtained with a fixation temperature of 110° C and a total time of 10 minutes. Consequently, the use of the polyisocyanate not only improves the wet rub fastness but also enables to reduce the total (drying + fixation) time.

[0039] Table 3 shows the results obtained with a composition according to the invention and having 2 % by weight of the first colour pigment and 3 % by weight of the second colour pigment. The composition had 1,5 % by weight of polyisocyanate.

Table 3

0 minutes fixation
Without corona						With 3D corona
1 bar		1.25 bar		1.5 bar		1 bar		1.25 bar		1.5 bar
drv	Wet	Drv	wet	drv	wet	drv	wet	drv	wet	drv	wet
4/5	3	4/5	2	1	1	4/5	2/3	4/5	2/3	¾	1

2 minutes fixation
Without corona						With 3D corona
1 bar		1.25 bar		1.5 bar		1 bar		1.25 bar		1.5 bar
drv	Wet	Drv	wet	drv	wet	drv	wet	drv	wet	drv	wet
4/5	¾	4/5	1/2	1	2/3	4/5	3/4	4	1	4/5	2/3

4 minutes fixation
Without corona						With 3D coror a
1 bar		1.25 bar		1.5 bar		1 bar		1.25 bar		1.5 bar
drv	Wet	Drv	wet	drv	wet	drv	wet	drv	wet	drv	wet
4/5	%	4/5	2	1/2	1	4/5	3	4/5	2	1	1

6 minutes fixation
Without corona						With 3D corona
1 bar		1.25 bar		1.5 bar		1 bar		1.25 bar		1.5 bar
drv	Wet	Drv	wet	drv	wet	drv	wet	drv	wet	drv	wet
4/5	¾	4/5	3	4/5	2	4/5	4	4/5	3/4	4/5	2/3

8 minutes fixation
Without corona						With 3D corona
1 bar		1.25 bar		1.5 bar		1 bar		1.25 bar		1.5 bar
dry	Wet	Drv	wet	drv	wet	drv	wet	drv	wet	drv	wet
4/5	¾	4/5	3/4	4/5	2/3	4/5	4	4/5	3/4	4/5	3/4

10 minutes fixation
Without corona						With 3D corona
1 bar		1.2 bar		1.5 bar		1 bar		1.25 bar		1.5 bar
drv	Wet	Drv	wet	drv	wet	drv	wet	drv	wet	drv	wet
4/5	4	4/5	4	4/5	4	4/5	3/4	4/5	3/4	4/5	3/4

[0040] Table 3 also shows the influence of increasing the fixation and curing time. The table 3 shows that a good dry rub fastness requires at least 6 minutes fixation time whereas a good wet rub fastness requires at least 8 minutes fixation time. The positive influence of the 3D Corona pre-treatment appeared at lower fixation times and high pressure.

[0041] Table 4 shows the results obtained with a composition having 2,5 % by weight of polyisocyanate.

Table 4

4 minutes fixation
1 bar		1.25 bar		1.5 bar
dry	wet	dry	wet	d ry	wet
4/5	3	4/5	3	4/5	3

6 minutes fixation
1 bar		1.25 bar		1.5 bar
dry	wet	dry	wet	dry	wet
4/5	3	4/5	¾	4/5	3/4

8 minutes fixation
1 bar		1.25 bar		1.5 bar
dry	wet	dry	wet	dry	wet
4/5	3/4	4/5	3/4	4/5	4

[0042] The use of a higher polyisocyante concentration reduces the drying and fixation time, as shown in table 4.

Claims

1. A composition for colour printing on a textile material, said composition comprising a first colour pigment, an aliphatic anionic polyurethane binder and an aliphatic polyisocyanate crosslinking agent, and wherein said composition further comprises an anionic acrylic polymer thickener, characterised in that for colour printing on said textile material, which is formed by a polypropylene needle punched textile material, in particular a polypropylene needle punched carpet, said aliphatic polyisocyanate forms 1 to 3 % by weight of the composition.

2. The composition as claimed in claim 1, characterised in that said aliphatic anionic polyurethane binder forms 20 to 50 % by weight of the composition.

3. The composition as claimed in claim 1, characterised in that said anionic acrylic polymer thickener forms 1 to 2 % by weight of the composition.

4. The composition as claimed in any one of the claims 1 to 3, characterised in that said aliphatic anionic polyurethane has a pH situated between 8.5 and 9.5 and forms at least 20 % by weight of the total composition.

5. The composition as claimed in any one of the claims 1 to 4, characterised in that said aliphatic polyisocyanate is water emulsifying.

6. The composition as claimed in any one of the claims 1 to 5, characterised in that said anionic acrylic polymer is formed by a mineral oil dispersion thereof and has a pH of 7, said anionic acrylic polymer forms at least 1 % by weight of the total composition.

7. The composition as claimed in any one of the claims 1 to 6, characterised in that said composition comprises a second colour pigment formed by white pigment and forming at least 3 % by weight of the total composition.

8. The composition as claimed in any one of the claims 1 to 7, characterised in that said composition has a viscosity of at least 4000 cP.

9. The composition as claimed in any one of the claims 1 to 8, characterised in that said composition comprises an anti-fungicide substance forming at least 1 % by weight of the total composition.

10. The composition as claimed in any one of the claims 1 to 9, characterised in that said composition comprises an anti-microbial substance forming at least 1 % by weight of the total composition.

11. A method for colour printing on a textile material by using a composition comprising a first colour pigment, an aliphatic anionic polyurethane binder and an aliphatic polyisocyanate crosslinking agent, and wherein said composition further comprises an anionic acrylic polymer thickener, characterised in that said aliphatic polyisocyanate binder forms 1 to 2 % by weight of the composition, said printing being realised on said textile material, which is formed by a polypropylene needle punched textile material, in particular a polypropylene needle punched carpet, said printing being realised by spraying said composition on said polypropylene needle punched textile material.

12. The method as claimed in claim 11, characterised in that a 3D Corona pre-processing is applied on said material before application of said composition.

13. The method as claimed in claim 11 or 12 characterised in that said composition is applied with a spraying pressure of at least one bar.

14. The method as claimed in any one of the claims 11 to 13, characterised in that said spraying is performed when said textile material is applied on a floor, and wherein for said spraying a spraying head is moved over said textile material.

15. The method as claimed in claim 14, characterised in that after spraying said composition, the latter is dried by applying heat on the sprayed composition.

16. The method as claimed in claim 14 or 15, characterised in that before spraying said composition an upper surface of said textile material is scanned in order to detect flatness irregularities in the textile material applied on the floor, and wherein upon detecting said flatness irregularities a distance between said spraying head and said upper surface is adjusted in order that said distance corresponds to a predetermined value.

17. A device for colour printing on a polypropylene needle punched carpet, characterised in that said device comprises a valve jet spraying head provided for spraying a composition having a viscosity of at least 4000 cP.

18. The device as claimed in claim 17, characterised in that said spraying head is movably mounted.

19. The device as claimed in claim 17 or 18, characterised in that it further comprises scanning means provided for scanning an upper surface of said textile material in order to detect flatness irregularities in the carpet when applied on a floor, said scanning means being further provided for adjusting, upon detecting said flatness irregularities, a distance between said spraying head and said upper surface in order that said distance corresponds to a predetermined value.

20. The device as claimed in claim 17, 18 or 19, characterised in that said device further comprises a 3D Corona generator provided for pre-processing said carpet before application of said composition.

21. The device as claimed in any one of the claims 17 to 20, characterised in that said device is mounted on a movable printing machine provided to be moved over a floor.