JP2013208863A - Transfer belt, method for manufacturing the same, and inkjet recording apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transfer belt capable of obtaining a high resolution image and an inkjet recording apparatus at low cost.SOLUTION: There is used a transfer belt of which ultraviolet ray transmittance is 70% or more, and which contains a polyethylene terephthalate or the polyethylene naphthalate of 95 mass% or more. Moreover, the manufacturing method includes: a molding step to mold the cylindrical belt by inflation molding; a cutting process to cut the belt into the desired length; and a diameter expansion processing process to expand the diameter by the diameter expansion rate 20% or less at the temperature vicinity of the glass transition point.

Description

  The present invention relates to a transfer belt used in an ink jet recording apparatus.

  Conventionally, a recording apparatus such as an ink jet printer mainly uses a method of directly spraying ink. However, the method of directly spraying ink is strongly influenced by the surface condition of the substrate, such as unevenness, undulation, and water repellency, and a high-quality image cannot be obtained.

  Accordingly, as one of the ink jet recording techniques, an ink image is formed on a transfer belt, the ink image formed on the transfer body is transferred to a desired recording medium, and the ink image is indirectly recorded on the recording medium. A scheme was proposed. When this method is used, compared with a method in which ink is directly sprayed onto a recording medium, a high-quality image can be obtained that is less affected by the surface condition of the printing material.

  As one of methods using this transfer belt, it has been proposed to use an ultraviolet transmissive resin such as polyimide or polyamide for the substrate of the transfer belt (see Patent Document 1).

JP 2010-228192 A

  However, the ultraviolet transmissive resin such as polyimide and polyamide used in Patent Document 1 is expensive. Further, as a method of processing a resin, the method of applying and baking a resin on a mold used in Patent Document 1 has a problem that productivity is low and cost is high.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a transfer belt, an inkjet recording apparatus, and the like that can obtain a high-quality image at low cost.

In order to achieve the above object, the present invention has the following features.
(1) A transfer belt having an ultraviolet transmittance of 70% or more and containing 95% by mass or more of polyethylene terephthalate or polyethylene naphthalate.
(2) The transfer belt according to (1), wherein the thickness is less than 0.2 mm.
(3) The transfer belt according to (1) or (2), wherein the step on the surface is less than 0.03 mm.
(4) The transfer belt according to (3), which is a seamless belt.
(5) When the transfer belt has a ring shape, the width of the transfer belt is L, the circumference of the ring at one end is R1, and the circumference of the ring at the other end is R2. The transfer belt according to any one of (1) to (4), wherein R1-R2 | / L × 100 has an accuracy of 1% or less.
(6) The transfer belt according to any one of (1) to (5), which has a surface layer containing a fluororesin on at least one surface.
(7) A material containing 95% by mass or more of polyethylene terephthalate is formed into a tubular shape by inflation molding, and a material is cut into a desired length by cutting the tubular material into a desired length. And a diameter expansion process step of expanding the material at a diameter expansion ratio of 20% or less in an environment of 45 to 75 ° C.
(8) A step of forming a material containing 95% by mass or more of polyethylene naphthalate into a cylindrical shape by inflation molding, a cutting step of cutting the cylindrically formed material into a desired length, and And a diameter expansion process step of expanding the material at a diameter expansion rate of 20% or less in an environment of 90 to 120 ° C., and a transfer belt manufacturing method.
(9) A transfer belt having an ultraviolet transmittance of 70% or more and containing 95% by mass or more of polyethylene terephthalate or polyethylene naphthalate, and a curable solution containing at least a curable material curable by ultraviolet rays are supplied onto the transfer belt. A means for forming an image receiving layer; a means for applying ink droplets to the image receiving layer formed on the transfer belt; and an ultraviolet ray for curing the image receiving layer to which the ink droplets have been applied. The means for irradiating the image receiving layer from the transfer belt side when contacting with the medium and the image receiving layer formed on the transfer belt are peeled from the transfer belt after contacting the recording medium. And a means for transferring the cured image-receiving layer from the transfer belt to the recording medium.

  According to the present invention, a transfer belt and an ink jet recording apparatus capable of obtaining a high quality image can be provided at low cost.

1 is a perspective view showing a transfer belt 1 according to an embodiment. The schematic block diagram which shows the inflation shaping | molding apparatus 51 which concerns on this embodiment. The figure which shows the ring body 64. FIG. Sectional drawing which shows the diameter-expansion processing apparatus 71 which concerns on this embodiment. 1 is a configuration diagram illustrating a recording apparatus 101 according to an embodiment.

  First, the transfer belt 1 according to an embodiment of the present invention will be described.

(Transfer belt structure)
FIG. 1 is a perspective view showing an example of the structure of a transfer belt 1 according to this embodiment. The transfer belt 1 is a cylindrical resin film. The transfer belt 1 preferably has a seamless structure.
The transfer belt 1 includes a resin having an ultraviolet transmittance of 70% or more at a wavelength of 280 nm or more and 400 nm or less measured by a spectrophotometer, and ultraviolet rays irradiated when the curable solution layer (image receiving layer) on the transfer belt 1 is cured. It is characterized by sufficiently transmitting and improving ink curability. The resin is selected from polyethylene terephthalate or polyethylene naphthalate, and the content in the transfer belt substrate is preferably 95% or more by mass. When the content of the resin is less than 95% by mass, it becomes cloudy and sufficient ultraviolet light transmittance cannot be ensured. Here, the transmittance is an average transmittance at a measurement wavelength of 280 nm to 400 nm.

  The thickness of the transfer belt 1 is greater than 0.02 mm, preferably less than 0.2 mm, and more preferably 0.03 mm or more and 0.15 mm or less. If the thickness is 0.02 mm or less, sufficient strength that can withstand the printing process cannot be obtained, and printing cannot be performed for a long time. Moreover, when it is 0.2 mm or more, sufficient ultraviolet light transmittance cannot be ensured.

  The step on the surface of the transfer belt 1 is preferably less than 0.03 mm. If it is 0.03 mm or more, the step shape is transferred and the print image quality is deteriorated. Note that, unlike the transfer belt 1 according to this embodiment, a transfer belt manufactured by bonding strip-shaped base materials with an adhesive or the like leaves a step of 0.03 mm or more at the joint portion.

  As shown in FIG. 1, when the width L of the transfer belt, the circumference of the ring at one end is R1, and the circumference of the ring at the other end is R2, | R1-R2 | / L × It is preferable that 100 has an accuracy of 1% or less. If | R1-R2 | / L × 100 exceeds 1%, the transfer belt tends to meander and the printing speed must be reduced. Note that the peripheral length and width of the transfer belt 1 can be appropriately changed depending on the size of the ink jet recording apparatus and the size of the object to be printed.

  The surface of the transfer belt 1 preferably has a surface layer containing a fluorine-based resin. Since the fluorine-based resin has low moisture hygroscopicity and good water repellency, the electrostatic adsorption property of the ink medium is increased, and the release property of the resin and the releasability of the resin component at the time of curing and fixing are also improved.

(Transfer belt manufacturing method)
Next, a method for manufacturing the transfer belt 1 will be described.
In order to manufacture the transfer belt with a seamless structure and high dimensional accuracy, the inflation molding process and the diameter expansion process are combined. FIG. 2 is a schematic configuration diagram showing the inflation molding device 51. The inflation molding device 51 includes a melt kneader 55, a ring body 64, a pinch roll 60, a winder 59, a roller 66, a roller 67, and the like. The melt kneader 55 is provided with a charging port 52 and a screw 56 inside. The screw 56 rotates inside the melt kneader 55 and feeds the molten resin pellet 53 introduced from the inlet 52 to the die 63 in a molten state. The melt kneader 55 is provided with a hole 58, and air 57 is blown into the hole 58. The die 63 has an annular lip and extrudes the fed resin into a cylindrical shape. As shown in FIG. 3, the ring body 64 is an annular member having a hollow portion 65 and is provided as needed to cool the extruded cylindrical resin by air cooling or water cooling. The pinch roll 60 extrudes air from the inside while winding the cylindrical resin film 61 between the two rolls and winds it up. The winder 59 winds up the resin film 61.

Next, the operation of the inflation molding device 51 will be described. The resin pellets 53 charged into the charging port 52 of the heated melt kneader 55 are melted, pumped by a screw 56, and extruded from a die 63 into a cylindrical shape. Since the air 57 is blown from the hole 58 to the cylindrical resin pushed out from the die 63 and the upper part is closed by the pinch roll 60, the cylindrical resin film 61 swells. After cooling through the hollow portion 65 of the ring body 64, a cylindrical bag body 62 is formed. That is, the DD cross section of the bag body 62 is circular. Then, after the air inside the bag body 62 is removed by the roller 66 and the pinch roll 60, the resin film 61 is sent by the roller 67 and taken up by the winder 59.
Inflation molding has very low dimensional accuracy, and therefore, in the inflation molding process, molding is performed under conditions that are smaller by about 10% than the desired circumference. After the resin film 61 formed into a cylindrical shape is cut to a desired length, the process proceeds to a diameter expansion processing step for the cut cylindrical resin film 61.

FIG. 4 is a cross-sectional view showing the diameter expansion processing device 71. The diameter expansion processing device 71 includes rollers 73a and 73b, a machine (not shown) for rotating the rollers 73a and 73b, a machine (not shown) for moving the rollers 73a and 73b in the B1 and B2 directions, respectively.
The diameter expansion processing device 71 rotates the rollers 73a and 73b that can rotate the resin film 61 processed into a cylindrical shape by the inflation molding device in the A direction, and at the same time, the two rollers 73a and 73b are separated from each other by B1. The transfer belt 1 is manufactured by moving in the direction B2 and the direction B2, respectively, and deforming to a desired circumference.

  When polyethylene terephthalate is used, the stretching temperature is preferably 45 to 75 ° C. which is equal to or slightly lower than the glass transition point of polyethylene terephthalate. When polyethylene naphthalate is used, 90-120 ° C. which is equal to or slightly lower than the glass transition point of polyethylene naphthalate is preferable. If the temperature is lower than that, circumferential vertical wrinkles will occur on the belt. If the temperature is higher than these, the tensile strength is too low and the belt is easily broken. Further, the transfer belt 1 is preferably removed from the rollers 73a and 73b after the transfer belt 1 is completely cooled. If the belt is removed at a temperature close to the diameter expansion temperature, the belt contracts again and the desired circumference cannot be obtained.

  The expansion ratio is 3% to 20%, preferably 3% to 10%. If it is less than 3%, a uniform cylinder diameter cannot be obtained. If it exceeds 20%, the belt will be wrinkled. The expansion ratio (%) = (peripheral length after diameter expansion process−minimum value of the peripheral length after inflation molding process) / minimum value of the circumferential length after inflation molding process × 100.

  After expanding the diameter at a high temperature, it is possible to shorten the circumference by raising the temperature again to a temperature exceeding 45 ° C. Although this shrinkage margin varies depending on the resin composition, it is the same as long as the diameter expansion rate is within 10%, so that the cylinder diameter is made constant in the width direction.

(Inkjet recording device)
Next, the recording apparatus 101 will be described. FIG. 5 is a configuration diagram illustrating an example of a recording apparatus according to the present embodiment. In the recording apparatus 101 shown in FIG. 5, a solution supply device 105, an inkjet recording head 107, a transfer device 109, and a cleaning device 111 are arranged on the outer periphery of a cylindrical transfer belt 103 in order from the upstream side in the transfer belt rotation direction C. ing. On the inner periphery of the transfer belt 103, an ultraviolet irradiation device 113, three support rolls 103a, 103b, 103c, and a pressure roll 109a are arranged.

  In FIG. 5, the transfer belt 103 is the transfer belt 1 of FIG. The transfer belt 103 is rotationally driven in the C direction. The solution supply device 105 supplies a curable solution 105a to the surface of the transfer belt 103 to form an image receiving layer 105b. The solution supply device 105 is formed of a supply roller 105d that supplies the curable solution 105a to the transfer belt 103 and a supplied curable solution 105a in a housing 105c that stores a curable solution 105a for receiving an ink image. And a blade 105e for defining the layer thickness of the image receiving layer 105b. Further, the solution supply device 105 is not limited to the above-described configuration, and a known supply method (coating method: for example, bar coater coating, spray coating, ink jet coating, air knife coating, blade coating, roll) A device using a method of application) is applied.

  The ink jet recording head 107 applies ink droplets 107 a to the image receiving layer 105 b formed on the transfer belt 103, and the three support rolls 103 a, 103 b, 103 c and the pressure roll 109 a are applied to the transfer belt 103 from the inner peripheral surface side. The ink droplets 107a are arranged so as to be rotated while being applied with tension, and the ink droplet 107a can be applied by the inkjet recording head 107 to the non-deflection transfer belt 103 that is rotated and supported by tension. The ink jet recording head 107 is a recording head for applying black ink, a recording head for applying cyan ink, a recording head for applying magenta ink, a recording head for applying yellow ink, or the like. May be arranged.

  The transfer device 109 includes pressure rolls 109a and 109b, a support body 117, a support roll 103c, and the like. The pressure rolls 109a and 109b sandwich the recording medium 115 such as paper and the transfer belt 103 to apply pressure. At this time, the image receiving layer 105 b on the transfer belt 103 contacts the recording medium 115. The support roll 103 c and the support body 117 maintain the state where the image receiving layer 105 b is in contact with both the transfer belt 103 and the recording medium 115 up to the peeling position 121. The ultraviolet irradiation device 113 cures the image receiving layer 105 b by irradiating the image receiving layer 105 b in contact with both the transfer belt 103 and the recording medium 115 with ultraviolet rays or the like from the inside of the transfer belt 103. The cleaning device 111 removes residues and foreign matters remaining on the surface of the transfer belt 103.

Next, the operation of the inkjet recording apparatus 101 will be described. The transfer belt 103 is moved in the C direction by the support rolls 103a and 103b, and the curable solution 105a is supplied by the solution supply device 105 to form the image receiving layer 105b.
Next, an ink droplet 107 a is applied to the image receiving layer 105 b formed on the transfer belt 103 by the ink jet recording apparatus 107.
Then, the image receiving layer 105b and the recording medium 115 are brought into contact with each other by the pressure rolls 109a and 109b, and ultraviolet rays are irradiated by the ultraviolet irradiation device 113, whereby the image receiving layer 105b is cured.

The image receiving layer 105b is peeled from the transfer belt 103 at the peeling position 121, and the image receiving layer 105b including the image 119 formed by the ink droplets 107a is formed on the recording medium 115 such as paper.
Residues and foreign matters remaining on the surface of the transfer belt 103 are removed by the cleaning device 111, and the curable solution 105a is again supplied onto the transfer belt 103 by the solution supply device 105 to form the image receiving layer 105b. The image recording process is repeated.

  In addition, as the ink jet recording apparatus, the recording apparatus 101 in which the image receiving layer 105b is provided on the transfer belt 103 and the image receiving layer 105b is transferred to the recording medium 115 has been described. However, the image receiving layer 105b is not provided, and The ultraviolet curable ink droplet 107a may be applied, and only the ink droplet 107a may be cured and transferred to the recording medium 115.

(Effect of this embodiment)
In this embodiment, by using inexpensive polyethylene terephthalate or polyethylene naphthalate as a base material and combining a diameter expansion method as a manufacturing method, it is possible to introduce an inflation molding method with high productivity but low dimensional accuracy. An inexpensive transfer belt can be provided. In addition, the transfer belt manufactured as described above has a seamless structure with high dimensional accuracy, and it is possible to suppress the surface level difference and increase the printing speed.

  EXAMPLES Hereinafter, although this invention is demonstrated further in detail based on an Example and a comparative example, this invention is not limited to these Examples.

  The transfer belts shown in Examples 1 to 8 and Comparative Examples 1 to 4 were produced by the following method. A seamless cylinder was obtained by blow molding the resin pellets. After this cylinder was cut to a desired length, the cylinder was stretched to a desired length by expanding the diameter while heating. After that, the roller was rotated and waited until the belt temperature reached room temperature, the space between the rollers was shortened, and the belt was removed. This was incorporated into a printing facility, and ultraviolet curable ink was adhered onto the belt from a jet nozzle, and ultraviolet light was irradiated from an opposite surface of the ink adhesion surface with an ultraviolet lamp while the adhesion surface was in close contact with the high-quality paper.

  The transfer belt used in Comparative Example 5 was prepared by connecting a biaxially stretched PET film having a thickness of 0.05 mm in a loop shape with ultrasonic bonding or hot melt adhesive so as to have a peripheral length of 1050 mm.

  Table 1 shows the resin used in each process, thickness, circumference, accuracy, diameter expansion rate, heat treatment temperature, ultraviolet transmittance, | R1-R2 | / L × 100, step, and print image quality.

  The ultraviolet transmittance of the transfer belt was determined as an average transmittance at a measurement wavelength of 280 nm or more and 400 nm or less based on the result measured with a spectrophotometer.

  The step on the surface of the transfer belt was measured using a non-contact shape measuring device (laser microscope), and the highest step in the measurement region was obtained.

  In Examples 1 to 4, good printed images were obtained. The ink on the paper surface was sufficiently cured, and even if the printed surface was immediately overlapped with another printed matter or touched with a hand, there were no problems such as ink transfer or bleeding. Also, the printed surface was very smooth, and it did not get scratched even if it was slightly rubbed with a toe.

  In Example 5 as well, a good print image was obtained as in Examples 1 to 4, but the equipment stopped while printing was performed for about 1 hour. When the equipment was disassembled, the belt stretched by about 10% and the desired belt tension could not be obtained. It is thought that the cause was that the driving force by the driving roller could not be endured.

  In Example 6, when the belt manufactured in the same manner as in Example 1 was heat-treated at 50 ° C. for 1 hour in a free state, the circumference was uniformly reduced by 2% to 1028 mm. When this was installed in a printing facility, it worked without any problems.

  In Example 7, in order to improve the inflation processability of PET, a belt was similarly constructed with a material added with 5% by mass of maleic anhydride-modified polyethylene. There wasn't.

  In Example 8, when a surface treatment such as silicone or fluorine was performed on the surface so that the ink was easily peeled off from the transfer belt, a good printed image was obtained.

  In Examples 1 to 8 and Comparative Examples 3 and 5, the ultraviolet transmittance was 70% or more.

  In Examples 1 to 8 and Comparative Example 4, | R1-R2 | / L × 100 was 1% or less.

  In Examples 1-8, the level | step difference was less than 0.03 mm.

  In Comparative Example 1, a transfer belt was made of polyvinylidene fluoride resin. When incorporated in a printing facility, there was a problem in that the amount of ultraviolet light transmitted was insufficient, the curing was insufficient, and the printed material was transferred when touched with a fingertip.

  In Comparative Example 2, when a belt having a thickness of 0.2 mm was made of PET and incorporated in a printing facility, the amount of ultraviolet light transmitted was insufficient as in Comparative Example 1, and the same problems as in Comparative Example 1 were observed.

  In Comparative Example 3, a 0.1 mm-thick cylinder having a minimum peripheral length of 870 mm after inflation molding with PET was obtained. When the diameter was expanded to 1050 mm at 50 ° C., the diameter expansion ratio exceeded 20%, so that wrinkles were generated in the portion having the minimum perimeter and the product could not be used. When the expansion temperature was set between 35-85 ° C., in any case, wrinkles or breakage occurred, and a product could not be made well.

  In Comparative Example 4, when a belt was formed in the same manner using a material obtained by adding 10% by mass of polyethylene modified with maleic anhydride to PET, the ink was poorly cured as in Comparative Example 1 because of strong white turbidity and low UV transmittance. There has occurred.

  In Comparative Example 5, a belt was manufactured by connecting a 0.05 mm thick biaxially stretched PET film in a loop shape so as to have a circumferential length of 1050 mm. This belt had sufficient strength and transparency, but had a level difference of at least 0.03 mm at the joint. The printed matter in the portion that hit the joint was in a situation where the step shape of the joint was transferred and the print quality was low. The joining method was tried by using a hot melt adhesive on the overlapping surface, heat fusion, etc., but in all cases, the step or unevenness remained 0.03 mm or more.

  The preferred embodiments of the present invention have been described above with reference to the accompanying drawings, but the present invention is not limited to such examples. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the technical idea disclosed in the present application, and these are naturally within the technical scope of the present invention. Understood.

DESCRIPTION OF SYMBOLS 1 ......... Transfer belt 51 ...... Inflation molding apparatus 52 ......... Inlet 53 ......... Resin pellet 55 ...... Mixing and kneading machine 56 ...... Screw 57 ...... Air 58 ...... Hole 59 ... ...... Take-up machine 60 ..... Pinch roll 61 ........ Resin film 62 .... Bag body 63 .... Die 64 .... Ring body 65 .... Hollow part 66 .... Roller 67 .... Roller 71... Diameter expansion processing devices 73 a and 73 b... Roller 101... Recording device 103... Transfer belts 103 a, 103 b and 103 c.
105a... Curable solution 105b... Image receiving layer 105c... Casing 105d. 109b... Pressure roller 111... Cleaning device 113... Ultraviolet irradiation device 115... Recording medium 117 ... Support 119 ... Image 121 ... Separation position R1 ... Transfer belt Of the other end of the transfer belt L ... the width A of the transfer belt ... the rotational directions B1, B2 of the rollers 73a, 73b ... of the rollers 73a, 73b Movement direction C ......... Rotation direction of the transfer belt 103

Claims (9)

  A transfer belt having an ultraviolet transmittance of 70% or more and containing 95% by mass or more of polyethylene terephthalate or polyethylene naphthalate.   The transfer belt according to claim 1, wherein the transfer belt has a thickness of less than 0.2 mm.   The transfer belt according to claim 1, wherein a step on the surface is less than 0.03 mm.   The transfer belt according to claim 3, wherein the transfer belt is a seamless belt. The transfer belt is ring-shaped,
When the width of the transfer belt is L, the circumference of the ring at one end is R1, and the circumference of the ring at the other end is R2, | R1-R2 | / L × 100 is 1% or less. The transfer belt according to any one of claims 1 to 4, wherein the transfer belt has an accuracy of 1.   6. The transfer belt according to claim 1, further comprising a surface layer containing a fluorine-based resin on at least one surface. A molding step of molding a material containing 95% by mass or more of polyethylene terephthalate into a tubular shape by inflation molding;
A cutting step of cutting the material formed into a cylindrical shape into a desired length;
A diameter expansion process step of expanding the cut material in an environment of 45 to 75 ° C. at an expansion ratio of 20% or less;
A method for manufacturing a transfer belt, comprising: A molding step of molding a material containing 95% by mass or more of polyethylene naphthalate into a tubular shape by inflation molding;
A cutting step of cutting the material formed into a cylindrical shape into a desired length;
A diameter expansion process step of expanding the cut material at a diameter expansion rate of 20% or less in an environment of 90 to 120 ° C .;
A method for manufacturing a transfer belt, comprising: A transfer belt having an ultraviolet transmittance of 70% or more and containing 95% by mass or more of polyethylene terephthalate or polyethylene naphthalate;
Means for supplying a curable solution containing at least a curable material curable by ultraviolet rays on the transfer belt to form an image receiving layer;
Means for applying ink droplets to the image receiving layer formed on the transfer belt;
Means for irradiating the image receiving layer from the transfer belt side, when the image receiving layer and the recording medium come into contact with each other, with ultraviolet rays for curing the image receiving layer provided with the ink droplets;
Means for transferring the cured image receiving layer from the transfer belt to the recording medium by peeling the image receiving layer formed on the transfer belt from the transfer belt after contacting the recording medium;
An ink jet recording apparatus comprising:

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