Transfer paper

Abstract

A transfer paper for heat transferring of ink to a textile, the transfer paper includes a base paper and a coating, and has a grease proof characteristics at a kit level of at least 3, such as 3 to 8, and the transfer paper having a dimensional stability of less than 1% over a period of 10 seconds.

Claims

1. A transfer paper for heat transferring of ink to a textile, the transfer paper comprising a base paper and a coating, wherein the transfer paper having grease proof characteristics at a kit level of at least 3, and wherein the transfer paper having a dimensional stability of less than 1% over a period of 10 seconds; wherein the coating comprises CMC and a saccharide, and wherein the transfer paper has a Cobb(60) value of 25 to 40 g/m.sup.2.

2. The transfer paper according to claim 1, wherein the coating comprises CMC.

3. The transfer paper according to claim 1, wherein the coating before application comprises CMC in an amount of 5-30% by weight of the coating.

4. The transfer paper according to claim 1, wherein the coating comprises CMC having a degree of substitution of at least 0.8.

5. The transfer paper according to claim 1, wherein the coating comprises a saccharide.

6. The transfer paper according to claim 1, wherein the coating before application comprises sorbitol in an amount of 5-50% by weight of the coating.

7. The transfer paper according to claim 1, wherein the transfer paper has a weight at most 80 grams per square meter.

8. The transfer paper according to claim 1, wherein the transfer paper has an air permeance measured according to SCAN-P 26:78 below 65 nm/(Pa.Math.s).

9. The transfer paper according to claim 1, wherein the transfer paper is adapted to withstand temperatures of at least 200 degrees Celsius.

10. The transfer paper according to claim 1, wherein the base paper is made using an amount of pulp, wherein said pulp comprises beaten pulp in an amount of at least 35% by weight of said amount of pulp.

11. The transfer paper according to claim 1, wherein the transfer paper has a Cobb(60) value of 25 to 50 g/m.sup.2.

12. The transfer paper according to claim 1, wherein the transfer paper comprises no more than 50 ppm of fluoride compounds.

13. A process for manufacturing a transfer paper, the process comprising the steps of: providing wood pulp, processing the wood pulp by beating and alkaline treatment to obtain a processed wood pulp, forming the processed wood pulp into a base paper, and applying a coating on the base paper to obtain a transfer paper having a Cobb(60) Value of 25 to 40 g/m.sup.2, wherein the coating comprises CMC and a saccharide.

14. An inked transfer paper for use for transferring ink to a textile, said inked transfer paper comprising a transfer paper according to claim 1, and at least one ink applied on a surface of said transfer paper.

15. The inked transfer paper according to claim 14 configured for transferring ink to a textile.

16. The transfer paper according to claim 1, wherein the transfer paper has grease proof characteristics at a kit level of 3 to 8.

17. The transfer paper according to claim 1, wherein the coating comprises sorbitol.

18. The transfer paper according to claim 1, wherein the transfer paper has a weight at most 40 grams per square meter.

Description

FIGURES

(1) The invention will now be described with reference to the figures where

(2) FIG. 1 illustrates a process for manufacturing a transfer paper according to an embodiment of the invention,

(3) FIGS. 2A-2B illustrate methods for applying the coating material according to embodiments of the invention, and

(4) FIG. 3 illustrates process of transferring ink from an inked transfer paper to a textile according to an embodiment of the invention.

DETAILED DESCRIPTION

(5) Referring to FIG. 1, a process for manufacturing a transfer paper TP is illustrated in accordance with an embodiment of the invention.

(6) In a first providing step S1, a wood pulp WP is provided. Various known wood pulps WP suitable for paper manufacturing may be used. In some alternative embodiments, pulp from non-wood sources may be used, e.g. rags or grasses.

(7) The wood pulp WP is then processed in a processing step S2 by beating and alkaline treatment to obtain a processed wood pulp PWP. The alkaline treatment may e.g. comprise treatment with sodium hydroxide or alternatively potassium hydroxide or similar strong bases. The amount of base is increased when weaker bases is applied. This step is performed extensively beyond the level usually applied, to obtain a relatively effective breakdown of the wood pulp, both physically and chemically.

(8) In embodiments of the invention, the beating continues until a relatively high degree of beaten cellulose pulp (also referred to a chemical cellulose pulp) is obtained, e.g. in the range of 35-65% by weight of the total amount of pulp. In the beaten cellulose pulp, the wood fibers are completely broken down primarily to cellulose, whereas the remaining pulp, the regular cellulose pulp, do comprise fibers.

(9) In embodiments of the invention, smaller amounts of antifoaming agent may be added to the wood pulp before and/or during the beating. Alternatively, or in addition thereto, wetting agent (surfactant) may be added, e.g. to increase interaction between the alkaline water and the wood fibers, which may otherwise be water repellant e.g. due to presence of tree resin.

(10) In embodiments of the invention, the beating may be carried out in various refiners, including commercially available refiners such as conical refiners and double disc refiners.

(11) Returning to FIG. 1, the obtained processed wood pulp PWP is then formed into a base paper BP in a paper forming step S3. As a part of this step S3, the formed wood pulp is dried to obtain dry base paper BP. This drying may typically comprise e.g. irradiation with infrared radiation, and/or heating by means of heated rolls. Heated air may also be used for drying. This drying may remove both free water in pores and interstices between the fibers, and also water absorbed into the fibers themselves.

(12) Typically, the processed pulp PWP obtained from the processing step S2 has a relatively high water content of about 98-99% by weight of the pulp. This water is gradually removed during the paper forming step S3.

(13) In an embodiment of the invention, removal of water during and/or preceding the paper forming step S3 is carried out as follows. First, water is sieved off. Then, pulp is squeezed to remove a further amount of water, and finally, the remaining water is wiped off.

(14) Returning to FIG. 1, in a coating step S4 a coating may be applied to the base paper BP. The coating is formed from a coating material CM, which may be applied step wise or in a single step. FIGS. 2A-2B illustrate various methods for applying the coating material CM. When the coating material CM has been deposited on the base paper BP, the final transfer paper TP is obtained.

(15) By using the above illustrated method, a transfer paper TP for heat transferring of ink to a textile TX may be obtained. This transfer paper TP comprises a base paper BP and a coating, and having grease proof characteristics at a kit level of at least 3, such as 3 to 8, and further having a dimensional stability of less than 1% over a period of 10 seconds.

(16) The coating material Cm used in step S4 may comprise one or more selected from the list of carboxy methylcellulose (CMC), polyvinyl alcohol, starch, alginate, gelatin, saccharides such as sugars and sugar alcohols, and combinations thereof.

(17) In embodiments of the invention, particularly preferred sugars include glucose, fructose, mannose, galactose, arabinose, xylose, ribose and combinations thereof.

(18) In embodiments of the invention, particularly preferred sugar alcohols include sorbitol, mannitol, and combinations thereof.

(19) The starches applied for the coating may in an embodiment e.g. be selected from a modified starch selected from the group comprising: an acid modified starch, an alkali modified starch, a bleached starch, an oxidised starch, an enzyme treated starch, an acetylated starch, an hydroxypropylated starch, a hydroxyethylated starch, and a carboxymethylated starch and a mixture thereof.

(20) Referring to FIGS. 2A and 2B, application of coating material CM to a base paper BP to obtain a transfer paper TP is illustrated according to embodiments of the invention.

(21) A first embodiment is illustrated in FIG. 2A. Here the coating material is dispensed from a coating material dispenser CMD e.g. via a suitably formed lip directly to the base paper BP, which moves around a roll RO in the direction indicated. This process may also be referred to as speed coating.

(22) Another embodiment is illustrated in FIG. 2B. In FIG. 2B, the base paper BP is fed through two opposing rolls RO. The coating material CM is here applied to one of the rolls RO, which then by rotation transfers the coating material CM to the base paper BP.

(23) It should be understood in the context of the embodiments of FIGS. 2A and 2B that single step coating application or multistep coating application may be applied.

(24) Referring now to FIG. 3, a process of transferring ink from an inked transfer paper ITP to a textile TX is illustrated according to an embodiment of the invention.

(25) As illustrated in FIG. 3, the inked transfer paper ITP is typically provided rolled up. Similarly, the blank textile TX is provided in roll form. The inked transfer paper ITP and the textile TX is then dispensed in a synchronous manner and joined at a cylinder roll RO and then concurrently moving towards the calender cylinder CC. The calender cylinder CC is heated to a temperature typically around 200 degrees Celsius. Upon contacting the calender cylinder CC, the inked transfer paper ITP is heated, and the ink is transferred from the inked transfer paper ITP to the textile TX to obtain an inked textile ITX.

(26) Normally, the inked textile ITX is then dried before being rolled on rolls.

(27) The used transfer paper TP is also rolled on rolls to facilitate transport e.g. to a paper mill for reprocessing, e.g. into a paper product.

(28) In embodiments of the invention, the surface temperature of the calender cylinder CC is 180 to 230 degrees Celsius.

(29) In an embodiment of the invention, an inked transfer paper ITP may be manufactured according to the following method: a) designing a data representation of a predetermined pattern of colors; b) feeding an ink jet printer with a transfer paper according to the invention or any of its embodiments; c) providing said ink jet printer with information corresponding to said data representation of said pattern of colors obtained in step a); d) allowing said ink jet printer to print a pattern of colors onto the transfer paper, said pattern of colors corresponding to the predetermined pattern of colors designed in step a).

(30) In one embodiment of the present invention said one or more inks are traditionally and/or conventionally ink-jet inks, such as inks comprising water and one or more dyes, optionally with further additives such as glycerol.

(31) Typically, inks of the colors black, cyan, magenta and yellow are used.

(32) Examples of useful inkjet inks to be used in the manufacture of the inked transfer paper are: S4 Subli Black 774, Elvajet Ultra Black SE 101, S4 Subli Cyan 770 Light, S4 Subli Cyan 770, Elvajet Blue SE 100, S4 Subli Magenta 770 Light, S4 Subli Magenta 770, Elvajet Magenta SE 100, S4 Subli Yellow 781, Elvajet Yellow SE 100, all from the supplier Sensient, Switzerland.

(33) Examples of usable industrial inkjet printers include: the Mimaki JV 33, Mimaki printer TS 500, and the Roland RS-640.

EXAMPLES

Example 1—Manufacturing of Base Paper

(34) Transfer papers are manufactured by the following method.

(35) First, the wood pulp is subjected to a careful processing comprising grinding (also referred to as beating) and alkaline treatment by sodium hydroxide. This processing is performed extensively, with total beating energy in the order of 300 kWh per ton of pulp to obtain pulp with a drainage resistance of about 70 SR (Schopper Riegler).

(36) Then, the processed wood pulp is formed into a base paper BP01 with a thickness adjusted such that the final dried base paper has a weight of about 40 grams per square meter.

(37) Further base papers were manufactured in accordance with table 1.

(38) TABLE-US-00001 TABLE 1 Base papers with different beating resulting in corresponding drainage resistance. Base paper BP01 BP02 BP03 BP04 BP05 Drainage 70 60 50 80 90 resistance

Example 2—Application of Coating

(39) A coating material is formed by mixing carboxymethylcellulose (CMC) with sorbitol. Ambergum™ 1221 was used as CMC, although other CMC products including such as Aqualon™ and Blanose™ from Ashland, was also used in similar tests. A 70% solution of sorbitol was used, 112090-Sorbitol 70% from DC Fine Chemicals. Sorbidex 200 from Toronto Research Chemicals has also been used in similar tests. The mixed coating material contained about 12% of CMC and about 20% of sorbitol. After mixing the coating material, the coating is then applied to the base paper BP01 of example 1 to obtain the final transfer paper TP01 (see table 2). Similarly, TP02-TP08 are made are made in accordance with table 2.

(40) TABLE-US-00002 TABLE 2 Manufacturing of base papers BP01- BP05 is described in example 1. Transfer paper TP01 TP02 TP03 TP04 TP05 TP06 TP07 TP08 Base paper BP01 BP02 BP03 BP04 BP05 BP01 BP01 BP01 Coating (content in wt. %) Sorbitol 20 20 20 20 20 12 30 15 CMC 12 12 12 12 12 12 20 — Starch — — — — — — — 15

(41) Transfer papers TP01-TP08 were all found to be substantially free of loose fibers and having a smooth, non-rough surface on the non-print side.

Example 3—Evaluation of Transfer Paper

(42) The dimensional stability of the transfer paper TP01 obtained in example 2 is tested and compared to commercially available Kaspar lite65 transfer paper.

(43) The test was performed on a Mimaki printer TS 500. The test was conducted at an ambient temperature 22 degrees Celsius and a room humidity of about 50%. The test was made with dark colors: (25 g/m2 water-based color of type Mimaki SB300). Paper tension in the printer was set to medium, the inside temperature of the machine was set to medium.

(44) The dimensional stability was measured at a section 10 seconds after printing of that section.

(45) For the transfer paper TP01, a dimensional stability (degree of expansion) of less than 0.12% was observed. For the commercially available Kaspar transfer paper, a degree of expansion of more than 1.0% was observed, i.e. more than 10 times more than TP01.

(46) Furthermore, the Kaspar paper displayed a number of lines that commonly occur as a result of cockling.

(47) No ink lines were observed in the transfer paper TP01, despite this paper with a weight of about 40 grams per square meter being significantly thinner that the Kaspar lite 65, which is labelled weight of 65 grams per square meter.

Example 4—Manufacturing of an Inked Transfer Paper

(48) A transfer paper TP01 obtained in example 2 was used. This paper was loaded on a Mimaki printer TS 500. The ink jet printer was supplied with ink of the type S4.Subli.770 (black, cyan, magenta and yellow).

(49) A print pattern comprising a spectrum of different colors was created on a personal computer. A representation of this pattern was sent to the inkjet printer via the corresponding software associated with the inkjet printer.

(50) The printer was allowed to print the predetermined pattern on a length of the transfer paper TP01.

(51) The applied ink was readily absorbed by the paper and the additive and the paper was sufficiently dry for packaging by rolling without any smearing of the ink occurring.

Example 5—Use of Inked Transfer Paper for Making an Inked Textile

(52) The inked transfer paper from example 4 was loaded onto a transfer calander machine (Klievrik T130). The calander temperature was adjusted to 210° C. The speed of the paper was adjusted so that the paper had a contact time on the calander rolls of 25 seconds. The pressure on the calander rolls was 3 bar. A polyester fabric of width 160 cm and length 100 m was fed concurrently through the machine together with the paper.

(53) The inked fabric was dried before being rewinded onto a roll. A quality control revealed that the obtained transferred ink pattern on the fabric was as high as on an inked fabric made by transferring the same ink pattern from a traditional transfer paper having a barrier coating of CMC.

Example 6—Kit Level

(54) The transfer paper TP01 evaluated for its level of greaseproof by establishing the kit level. The TAPPI UM 557 was used to determine the kit level.

(55) A kit level of 7 was obtained for TP01.

FIGURE REFERENCES

(56) S1. Wood pulp providing step S2. Processing step S3. Paper forming step S4. Coating step WP. Wood pulp PWP. Processed wood pulp BP. Base paper CM. Coating material CL. Coating layer TP. Transfer paper CMD. Coating material dispenser RO. Roll ITP. Inked transfer paper TX. Textile ITX. Inked textile CC. Calender cylinder IN. Ink