JPH05116475A - Surface-improved stencil and method for improving the surface - Google Patents

Abstract

PURPOSE:To obtain a surface-modified stencil which does not generate running- out of printing during continuous printing; has a thin treated layer; does not clog gaps of a screen mesh and a porous supporting body; is fixed strongly on the plate material; is easily washed by performing the modification treatment of the surface of the stencil with a compd. having a perfluoro group. CONSTITUTION:Modification treatment of the surface of a stencil is performed by using a compd. having a perfluoro group. The above described compd. having a perfluoro group is either a silane compd. selected from at least one among perfluoroalkyl groups, perfluoroalkenyl groups and perfluoroaryl groups or a titanate compd. selected from at least one among perfluoroalkyl groups, perfluoroalkenyl groups and perfluoroalkenyl groups and perfluoroaryl groups. As the result, a surface-modified stencil which does not generate running-out of printing during continuous printing; has a thin treated layer; does not clog openings of a screen mesh and a porous supporting body; is foxed strongly on the plate material; is easily washed, is obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stencil used for screen printing, a metal mask, or a stencil such as a heat-sensitive stencil sheet, which has been surface-modified, and a method for surface modification thereof.

[0002]

2. Description of the Related Art In conventional screen printing plates, the plate material does not have water / oil repellency with respect to the printing ink. Therefore, when printing continuously, the printing ink is applied to the printing material in the image area. Prints bleed on the back side of the contact surface. on the other hand,
Compared to screen masks, metal masks can meet the demands when thicker patterns and three-dimensional patterns are required. However, when the printing amount per unit area increases, printing ink is printed on the metal mask. Print bleeding also occurs around the surface contacting the body, which not only makes the printing unclear, but also causes electrical contact between the patterns. As a method of preventing these, there is a method of making the surface in contact with the printing object or the surface of the plate material water-repellent or oil-repellent so as to prevent printing bleeding. For example, a homopolymer of an acrylate having a perfluoroalkyl group, a copolymer of an ethylenically unsaturated monomer copolymerizable with these monomers, a sulfonamide having a perfluoro group, a carboxylic acid , A siloxane derivative or the like is applied to a screen for printing, water-repellent and oil-repellent treatment is performed, and the paste does not fly off even when the screen is rapidly detached from the object to be coated. Sho 51
No. 29588), a water-repellent resin such as a fluorine-containing acrylic acid ester copolymer, a fluorine-containing polyester rubber, or a silicone resin is coated on the emulsion surface, and the same portion as the uncured portion of the emulsion is repelled during development after exposure. A water-repellent / oil-repellent screen printing plate that allows water-based resin to flow out (JP-A-2-76792).
JP-A-56-6), an ink printing method using a metal mask for forming a water-repellent resin film having a thickness of several μm or less by baking and curing silicon and polytetrafluoroethylene (JP-A-56-6).
No. 7985).

The heat-sensitive stencil sheet is manufactured by laminating a heat-sensitive stencil layer made of a thermoplastic resin and a porous support. This heat-sensitive stencil sheet is brought into close contact with a document made of a colorant having a good heat-absorbing property, irradiated with light, and the heat-sensitive stencil layer of the heat-sensitive stencil sheet adhered by the heat absorbed in the printed portion of the document is adhered. It is made by melting and punching,
In printing, this base paper is wrapped around an ink drum, for example, and ink is supplied from the porous support side for printing. In this case as well, since the heat-sensitive stencil layer comes into contact with the printing paper, printing bleeding occurs due to the backside of the ink.

Further, when the thickness of the heat-sensitive stencil layer becomes thick, it becomes difficult for ink to be supplied from the side of the porous support to pass through during printing, and a large amount of heat-melted polymer remains around the perforations during heating and the plate-making accuracy is improved. Since it deteriorates, it is preferable that the thickness of the heat-sensitive stencil layer is as thin as possible, but there is a problem that when the thickness is reduced, printing durability is deteriorated. In order to solve these problems, there is a method of rendering a porous support or a heat-sensitive stencil sheet water-repellent or oil-repellent. For example, a heat-sensitive stencil printing method in which a porous film support is impregnated with a water-repellent / oil-repellent substance such as a fluorine-based activator, wax or metal soap (JP-A-61-2).
No. 9594), a heat-sensitive stencil sheet on which a water-repellent coating of a water-repellent resin such as a silicone resin or a fluororesin or a low water-absorption resin such as a polyvinyl chloride resin or a phenol resin is formed in a porous thin leaf material by an immersion method. (JP-A 1-2144
No. 81), a polyester film in which the surface of a polyester, which is a thermoplastic resin, is made water-repellent by using an aqueous dispersion of a basic compound of a polysiloxane graft polymer, and its use and production method (JP-A-2-269133).
And so on.

[0005]

[Problems to be Solved by the Invention] However, it is impregnated and coated with a fluorine-based resin or a silicone-based resin to make it water repellent.
In the oil-repellent method, voids such as a screen mesh and a porous support are closed, and the opening becomes thinner than the actual size due to the thickness of the resin coating, resulting in a reduction in resolution. Therefore, it cannot be used for fine patterns. Further, if only the surface that comes into contact with the material to be printed is made water and oil repellent, the inner wall of the opening is not treated, so that the amount of printing ink remaining increases and the printing accuracy deteriorates. Further, since the method of baking and curing silicon or polytetrafluoroethylene requires a high temperature, it cannot be used with a screen mesh such as polyester or polyamide which has no heat resistance at the baking temperature.

In addition, in these methods, the interaction acting between the stencil surface and the compound that imparts water / oil repellency is very weak, and therefore, deterioration of performance such as peeling, abrasion and deterioration of the compound coating is likely to occur. There is a drawback that the effect does not last for a period of time. Further, conventionally, fluorine-based resins and silicon-based resins form a low energy surface as compared with other hydrocarbon-based resins, and are therefore widely used as release agents, water repellents, etc. The surface has a contact angle with water of 90 ° to 100 °, the wettability with printing ink is not sufficiently low, and it is still insufficient for use in antifouling property, water repellency, oil repellency, etc. is there.

[0007]

It is an object of the present invention to prevent bleeding from occurring even in continuous printing in a stencil, the thickness of the treated layer is very thin, and the plate material is not blocked by the screen mesh or the porous support. The present invention provides a surface-modified stencil and a method for surface-modifying the same which are firmly fixed to the surface of the stencil and have a surface contact angle of about 120 ° with water, and which are easy to wash.

[0008]

The surface-modified stencil according to the present invention has a surface energy lower than that when a conventional fluorine-based resin, silicon-based resin or the like is used, and is bonded or adsorbed to the surface of the stencil. It is made water and oil repellent by treating with a compound having a perfluoro group that can be fixed by a strong interaction such as.

The compound having a perfluoro group used in the present invention is a silane compound selected from perfluoroalkylsilane, perfluoroalkenylsilane and perfluoroarylsilane, or perfluoroalkyl titanate, perfluoroalkenyl titanate and perfluoro. It is selected from titanate compounds selected from aryl titanates. The perfluoroalkyl group is represented by Rf ₁ , the perfluoroalkenyl group is represented by Rf ₂ , and the perfluoroaryl group is represented by Rf ₃ .

[0010]

[Chemical 1]

[0011]

[Chemical 2]

[0012]

[Chemical 3]

The compound having a perfluoro group has a lower critical surface tension as the chain length of the perfluoro group becomes longer, but preferably, the compound having a chain length of 7 or more carbon atoms is preferred. Examples of the hydrolyzable group of silane and titanate include a chloro group, an acetoxy group, an alkylamino group and a propenoxy group, in addition to the alkoxy group. Further, regarding the number of hydrolyzable groups of silane and titanate, the trifunctional surface has a smaller critical surface tension than the bifunctional surface. This is 3
Since the functional one takes a resin structure through hydrolysis and condensation,
It is considered that this is because the treatment density is increased and the orientation is also enhanced. To improve the orientation, introduce a polar group (amide group, sulfonamide group, etc.) into the perfluoroalkyl chain,
This can be achieved by causing interactions such as hydrogen bonds between molecules and orienting them in a fixed direction.

In general, the interaction between the compound having a perfluoro group and the surface of the object to be treated is the chemical bond between the hydroxyl group on the surface of the object to be treated and the compound having the perfluoro group, --Si--O--. Alternatively, a -Ti-O- bond is formed, a reversible equilibrium reaction occurs between a hydroxyl group on the surface of the object to be treated and a silanol group derived from a compound having a perfluoro group, or the surface of the object to be treated is It is believed that a single molecular layer is formed to form a couple of molecular layers by physically adsorbing to.

In the present invention, it is thought that the same interaction as described above will occur, and the compound having a perfluoro group is firmly fixed to the surface of the stencil by binding or adsorption, and furthermore, an extremely thin layer is formed. Conceivable. Specific examples of the compound having a perfluoro group are shown below, but the invention is not limited thereto.

RF ₃ CH ₂ CH ₂ Si (OCH ₃ ) ₃ RF ₃ CH ₂ CH ₂ Si (CH ₃ ) (OCH ₃ ) ₂ RF ₃ COO (CH ₂ ) ₃ Si (OCH ₃ ) ₃ RF ₃ COS (CH ₂ ) ₃ Si (OCH ₃ ) ₃ RF ₃ CONH (CH ₂ ) ₃ Si (C ₂ H ₅ ) ₃ RF ₃ SO ₂ NH (CH ₂ ) ₃ Si (C ₂ H ₅ ) ₃ RF ₃ CH ₂ CH ₂ SCH ₂ CH ₂ Si (OCH ₃ ) ₃ RF ₃ CH ₂ CH ₂ SiCl ₃ RF ₃ CH ₂ CH ₂ Si (CH ₃ ) Cl ₂ RF ₃ CH ₂ CH ₂ Si (CH ₃ ) ₂ Cl RFCH ₂ CH ₂ OCONH (CH ₂ ) ₃ SiCl ₃ RFCH ₂ CH ₂ NH (CH ₂ ) ₂ SiCl ₃ RFCONHCH ₂ CH ₂ NH (CH ₂ ) ₃ SiCl ₃ RFSi (CH ₃ ) ₂ Cl (RFCOO) ₃ TiOCH (CH ₃ ) ₂ (however, RF = Rf ₁ , Rf ₂ , Rf ₃ )

[0017]

[Chemical 4]

As the surface modification method, a solution obtained by dissolving these compounds having a perfluoro group in an organic solvent is used, and the entire surface of the stencil or a part of the vicinity of the opening is dipped, sprayed, squeezed, and coated with a plate. Then, air-drying or heat-drying or, if necessary, heat treatment is performed. Examples of the organic solvent include alkanes such as n-hexane, n-heptane and n-hexadecane, aromatic hydrocarbons such as benzene and toluene, ketones such as acetone and methyl ethyl ketone, cyclopentadiene and fats such as cyclopentane. Ring hydrocarbons, halogenated hydrocarbons such as carbon tetrachloride, chloroform, methylene chloride, ethyl ether, isopropyl ether,
Compounds having a perfluoro group in which ethers such as dioxane, esters such as ethyl acetate and butyl acetate, alcohols such as methanol, ethanol and isopropanol, water and the like having a perfluoro group are dissolved or uniformly dispersed One or a mixture of two or more solvents that do not show reactivity with can be used, and it is advisable to select and use a solvent that swells and dissolves the image of the stencil and does not deteriorate the image accuracy. In addition, the solution concentration is 2.0 although it depends on the compound having a perfluoro group.
Even with x10 ^{-4 to} 5.0 x 10 ^-2 mol / l, the effect can be sufficiently obtained.

If the compound has a perfluoro group that vaporizes at room temperature, it can be rendered water and oil repellent by vapor phase treatment using steam. In this case, the compound having a perfluoro group may be used alone or may be diluted with the above organic solvent. When the treatment is carried out in the gas phase, since the stencil surface has very few unreacted perfluoro group-containing compounds, there is almost no need for post-treatment, and the workability is improved. Moreover, it is possible to process a plate material having low solvent resistance and water resistance without causing performance deterioration. Also, when using one that is easily hydrolyzed,
It is more preferable to carry out the treatment in an atmosphere of an inert gas such as N2 or He because the influence of moisture in the atmosphere is small.

The immersion time and the gas phase treatment time differ depending on the kind of the compound having a perfluoro group used, the treatment temperature, and the flow rate of the inert gas, but are generally between 10 seconds and several tens of minutes. The treatment for imparting water and oil repellency may be performed before plate making, but is preferably performed after plate making. In addition, if water-repellent / oil-repellent treatment is applied not only to the surface of the plate material that contacts the substrate, but also to the ink supply side, the printing ink will not remain on the surface. Can be done in a short time and with a small amount of washing solvent.

Further, in the present invention, the formation of the water-repellent / oil-repellent treated layer using the compound having a perfluoro group makes it difficult for the printing ink solvent to be absorbed by the plate material or the heat-sensitive stencil layer. As a result, swelling and deformation of the above materials due to the solvent do not occur, so that the printing accuracy and printing durability are improved.

[0022]

When the surface of the stencil is coated with a fluororesin or a silicone resin, the contact angle to water is 90 ° to 100 °, whereas when the method of the present invention is used, the contact angle to water is 120 °. Before and after, the surface energy is lower than that in the case of coating with a fluorine-based resin or a silicon-based resin, and the water / oil repellency is further improved. Further, since the treatment layer is from a monomolecular layer to a few molecular layers, it is very thin, clogging of the plate material does not occur, and the accuracy of the plate does not decrease. Further, since the interaction between the compound having a perfluoro group and the surface of the stencil is very strong, the effect is maintained without peeling.

[0023]

EXAMPLE FIG. 1 shows a screen printing plate of the present invention and a state of printing using the screen printing plate. The surface modification layer 4 is firmly fixed to the surface of the screen mesh 2 and the surface of the plate material 3, and the plate frame 1 Ink 6 which has passed through the holes of the plate material 3 fixed to the
Is printed on the printing medium 5.

Examples of the present invention will be described below for more specific description. Example 1 Screen mesh made of polyester mesh # 22
A printing plate was prepared using 5T (NBC Industry Co., Ltd.) and a diazo direct method emulsion Super King BS-40M (Tokyo Ohka Kogyo Co., Ltd.) as the emulsion. The line width is 50μ on the original to test the plate condition and printing performance by processing.
A 1 mm resolution chart was used. After plate making, n-
1H, 1H, 2H, 2H- in 50.00g of hexadecane
A treatment liquid in which 0.12 g of perfluorodecyltrichlorosilane was dissolved was prepared, and the whole plate was subjected to vapor phase treatment at 40 ° C. for 3 minutes while stirring the treatment liquid. As a result of this process,
It was possible to obtain a surface-treated layer having a very high water / oil repellency (contact angle to water: 118 °) without blocking the fine lines and mesh openings of the plate-making portion. In the same edition, oil-soluble printing ink, Pro Steel # 400 (SEIKO ADVANCE
Continuous printing was performed.

As a result of comparing the reproducibility of the printed matter with an image line having a width of 200 μm, the image lines of some untreated sheets began to thicken, and contact between the image lines partially occurred due to the backing. On the other hand, in the case of several hundreds of processed sheets, the printing ink was well cut off, and there was no thickening of the drawing lines due to the backing, and no contact of the drawing lines was observed. Thus, the surface-modified stencil of the present invention was able to greatly improve continuous printability. Furthermore, since the printing ink does not remain on the plate surface after printing after printing, a small amount of washing solvent was required, and there was no clogging with the printing ink, and washing could be done easily in a short time.

Example 2 Screen mesh made of polyester mesh # 27
0 (NBC Industry Co., Ltd.), and the emulsion used diazo-based capillary film ULANO CDF-4 (ULANO).
To produce a printing plate. An original having a line width of 2 mm was used to test the condition of the plate and the printing performance by the water and oil repellent treatment of the present invention with an aqueous ink. After plate making, n
-1H, 1H, 2H, 2H- in 300.00 g of hexane-
Prepare a treatment solution in which 0.25 g of perfluorooctyltrichlorosilane is dissolved, immerse the plate in this treatment solution, and
Liquid phase treatment was performed for a minute. As a result of this treatment, it was possible to obtain a treated surface having a very high water / oil repellency (contact angle to water: 115 °) without blocking the openings of the mesh. With the same edition, continuous printing was performed using a water-soluble printing ink, AQUASET (manufactured by Jujo Kako).

As a result of comparing the reproducibility of the printed matter with the image lines, the stickiness of the plate surface occurred and the threading phenomenon of the image lines was observed from several sheets of the untreated one. On the other hand, compared with the non-treated paper, the treated paper was less likely to cause stickiness on the plate surface, and the stringing phenomenon of the image line was not observed, and the printing could be performed with high accuracy. As described above, the surface-modified stencil of the present invention was able to greatly improve the printing durability of the water-based ink. Further, since the printing ink does not remain on the plate surface and the plate frame in the plate washing after printing, a small amount of the washing solvent was required, and the printing ink could not be clogged, and the washing could be performed easily in a short time.

[0028]

According to the present invention, the surface of the stencil has a surface energy lower than that of the fluororesin or the silicone resin,
By firmly fixing the whole plate with an extremely thin treatment layer, it was possible to greatly improve the water and oil repellency with respect to the printing ink. As a result, even when printing is continuously performed with the oil-based ink or the water-based ink, it is possible to prevent the back surface of the printing ink from coming into contact with the surface to be printed and to prevent the occurrence of printing bleeding. Further, the plate separation of the printing ink is improved, and it is possible to continuously obtain a highly accurate and reproducible printing pattern. Also, the plate washing after printing is easy because the printing ink does not easily adhere to the plate, and the washing solvent is small. In addition, since the solvent can be prevented from penetrating into the plate, printing durability is improved.

Further, since no resin is used, it does not block the voids of the screen mesh, the porous support and the like, and since the treatment layer is extremely thin, it does not affect the printing pattern of the stencil. Moreover, since the interaction between the stencil surface and the compound having a perfluoro group is strong,
The effect can be maintained even after long-term use.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example when printing ink is printed on a screen printing plate of the present invention and a printing medium.

[Explanation of symbols]

 1 ... Plate frame 2 ... Screen mesh 3 ... Plate material 4 ... Surface modification layer 5 ... Printed material 6 ... Printing ink

Claims (4)

[Claims] 1. A surface-modified stencil characterized in that the surface of the stencil is modified by using a compound having a perfluoro group. 2. A silane compound in which the compound having a perfluoro group is selected from at least one of a perfluoroalkyl group, a perfluoroalkenyl group and a perfluoroaryl group, or the perfluoroalkyl group and the perfluoro group. 2. A titanate compound selected from at least one of an alkenyl group and the perfluoroaryl group.
The surface-modified stencil described. 3. A method for modifying the surface of a stencil, which comprises modifying the surface of the stencil with a compound having a perfluoro group. 4. A silane compound in which the compound having a perfluoro group is selected from at least one of a perfluoroalkyl group, a perfluoroalkenyl group, and a perfluoroaryl group, or the perfluoroalkyl group and the perfluoro group. 4. A titanate compound selected from at least one of an alkenyl group and the perfluoroaryl group.
A method for modifying the surface of a stencil as described.