JP3419077B2 - Base paper for thermal stencil printing - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sensitive stencil sheet. More specifically, the present invention relates to a heat-sensitive stencil sheet having excellent printing clarity and antistatic property. 2. Description of the Related Art The basic components of a heat-sensitive stencil sheet are two members, a film and a porous support, which are tightly laminated and bonded to each other. The reason for this is that the film is extremely thin with a thickness of 5 μm or less in order to obtain perforation properties. It is not only strong and inconvenient to handle, but also deforms or distorts during thermal plate making with a thermal head or perforates. This is to prevent the parts from falling off and not to use them. In general, a polyester film (hereinafter simply referred to as a film) is used as a film, and a nonwoven fabric or paper is used as a porous support. In particular, Japanese paper that is porous and thin but has high strength is preferably used. Thermal plate making with a thermal head or the like is performed by perforating a film. At this time, the paper of the support is not perforated.
Printing is performed by moving ink through a perforated portion of a film to a printing medium. However, there is a drawback that the fiber layer of the paper has unevenness in thickness and clogging of the ink is apt to occur, making it difficult to obtain a clear printed matter. In order to solve this drawback, it is conceivable to use a screen gauze made of polyester fiber as a support. By using a screen gauze as a support, unevenness in thickness is reduced, and printing clarity is improved as compared with a nonwoven fabric, but an adhesive is indispensable when laminating the film. Therefore, the selection of the adhesive, the method of applying the adhesive, and the method of laminating the two members have been important factors influencing the quality of the heat-sensitive stencil sheet. That is, the amount of the adhesive affects the perforation sensitivity, and in addition to affecting the perforation property, a residue is likely to be generated after perforation, impeding the passage of ink, and the improvement effect is small. In particular, it was not possible to improve the density unevenness of the ink in solid printing. [0005] Further, adhesives generally have a problem in solvent resistance, and usable inks are limited. For this reason, there was a drawback that printing on plastic could not be performed. Further, the steps of applying and drying the adhesive on the screen gauze and / or the film are required, and there are problems in that the steps are complicated and in the step management for obtaining uniformity of the application. Further, when the screen gauze and the film are all made of polyester, they did not become apparent when Japanese paper was used, but there was a problem of electrostatic damage. [0007] As a specific obstacle, when a heat-sensitive stencil sheet to which fine foreign matter adheres is perforated with a thermal head to make a plate, the portion to which the foreign matter adheres remains without being perforated.
This results in poor printing. In particular, when the perforation density is increased in order to increase the printing accuracy, the above-mentioned disadvantage becomes more remarkable. SUMMARY OF THE INVENTION An object of the present invention is to provide a heat-sensitive stencil sheet having excellent printing clarity and antistatic property in view of the conventional disadvantages. An object of the present invention is to provide a polyester film having a thickness of 5 μm or less and a core having a low melting point polyester as a sheath component to which an antistatic agent is attached.
Woven screen mesh cloth having a heat-adhesive consisting of sheath composite yarn
This can be attained by forming a heat-sensitive stencil base paper in which a material is laminated and heat-bonded. The present inventors have conducted intensive research on a heat-sensitive stencil sheet having excellent printing clarity and antistatic properties, and have found that a heat-adhesive polyester screen gauze support (hereinafter, referred to as a support).
The application of an adhesive is not required by laminating and thermally bonding using a screen gauze), and the generation of static electricity is prevented by attaching an antistatic agent to the surface of the screen gauze in advance. Have been found to be achieved. As the polyester film to be laminated and adhered to the screen gauze of the present invention, a polyethylene terephthalate film comprising terephthalic acid and ethylene glycol is preferably used, and a third component of 30 mol% or less as an acid component and / or a diol component is commonly used. It may be a polymerized or mixed polyester film. In particular, it is preferable to use a component similar to the heat-adhesive polyester of the screen gauze as the third component because the lamination heat-adhesiveness is further enhanced. The polyester film to be laminated and bonded to the screen fabric of the present invention preferably has a thickness of 5 μm or less.
Preferably it is 1 to 4 μm. Torn ease rather Nari when thinner laminated with screen mesh cloth is thermally bonded than 1 [mu] m, also becomes thicker than 5μm perforation sensitivity by the thermal head or the like is lowered. Screen mesh cloth woven with thermal adhesiveness [0013] The present invention
The object, the sheath component is a low melting polyester having a melting point of 170 to 230 ° C., preferably woven in screen mesh using a core-sheath type composite fiber core component consists of melting point 250 ° C. or more polyesters. This is because the adhesiveness to the polyester film to be laminated and heat-bonded is excellent, and there is no peeling at the interface of the composite fiber, so that more reliable thermal adhesion can be obtained. In addition, due to the core-sheath type composite structure fiber, the press pressure acts reliably between the low melting point component of the support and the film during lamination heating press due to the high elastic modulus of the core component, and uniform and strong adhesive force Can be obtained. [0014] conjugate form is required to be concentric core-sheath type composite. Although only the core component may have a modified cross section or a multi-core shape, in this case, it is preferable to make the core component symmetrical. Further, a part of the core component may be exposed on the surface of the composite fiber. The cross-sectional shape of the core-sheath type composite fiber is preferably circular. The reason for this is that the deformed cross-section yarn is more likely to curl than a circular shape and has drawbacks such as difficulty in obtaining a screen having a uniform opening (opening). Core sheath
The structure of the type composite fiber may be either a monofilament or a multifilament. In the case of multifilament,
It is necessary to bundle the fibers by twisting about 800 to 2000 T / m. When the melting point of the core-sheath type composite fiber sheath component is less than 170 ° C., the low melting point component softens at the stretching heat treatment temperature, which makes not only the stretching operation difficult but also the unwinding property of the wound stretched monofilament. When weaving on screen gauze, problems such as vertical streaks, horizontal stairs, and shrinkage occur. On the other hand, if the melting point exceeds 230 ° C., good thermal adhesion cannot be obtained. Also,
It is necessary to increase the lamination thermal bonding temperature with the polyester film, and the heat shrinkage of the screen fabric and the polyester film becomes large, and wrinkles are easily generated on the heat-sensitive stencil sheet. For this reason, there arises a problem that a perforation property cannot be obtained by a thermal head or the like. As such a sheath component, a dicarboxylic acid such as isophthalic acid, adipic acid, dimer acid, and sebacic acid is used as an acid component in the high melting point component, while a diol component is used such as neopentyl glycol, diethylene glycol, cyclohexane dimethanol, and the like. Is preferably 15 to 40 mol%, more preferably 2 to 40 mol%.
It is obtained by copolymerizing 0 to 30 mol%. The core component is preferably polyester having a melting point of 250 ° C. or higher, preferably 30 ° C. or higher than the melting point of the sheath component. The melting point of this core component is 250 ° C
The, since the difference in melting point between the sheath component becomes small, the sheath <br/> component and breaking strength heat-treated at a temperature around the melting point, as problems such as physical properties such as elastic modulus decreases significantly occurs less than . As such a high melting point component, polyethylene terephthalate, which is generally used for clothing and industrial materials, is most preferable, but polyethylene-2, which has a higher elastic modulus, is more preferable.
6-naphthalate or wholly aromatic liquid crystal polyester can also be used. These high melting point polyesters are most preferably homopolyesters, but if necessary, acid components such as adipic acid, sebacic acid and 1,4-cyclohexanedicarboxylic acid and / or tetramethylene glycol, cyclohexanedimethanol, neopentyl glycol, etc. A diol component such as polyoxyalkylene glycol can be copolymerized as the third component, preferably at most 5 mol%. The composite ratio of the sheath component is 10% in cross-sectional area ratio.
５０50%, preferably 20-40%. When the composite ratio of the sheath component is 50% or more, in addition to the above-mentioned properties such as high breaking strength, high modulus, and dimensional stability, shrinkage due to heat at the time of laminating becomes large, so that good adhesiveness can be obtained. There is no problem. From this viewpoint, the free shrinkage of the polyester fiber constituting the screen gauze measured at 160 ° C. is preferably 20% or less. On the other hand, if the composite ratio of the sheath component is 10% or less, there is a problem that a sufficient bonding area cannot be obtained at the time of lamination and the bonding strength is reduced. As a matter of course, known additives such as titanium dioxide, an ultraviolet absorber and an organic silicate compound can be used for the sheath component and / or the core component, if necessary. In particular, when titanium oxide is added in the range of 0.1 to 0.4% by weight to the sheath component and / or the core component, the friction coefficient of the yarn surface can be reduced, and the core sheath having excellent uniformity can be obtained.
Mold composite fibers can be obtained. In addition, scum can be suppressed in weaving, which is preferable. As a specific method for obtaining the core-sheath type conjugate fiber of the present invention, a conventionally known conjugate spinning method can be applied. That is, the polymers forming the core component and the sheath component are individually melt-weighed, merged so as to form a core-sheath composite structure on the back surface of the mouthpiece, discharged from the same discharge hole, and a conventionally known fiber treatment agent is applied. The obtained undrawn yarn is drawn and wound by a drawing device comprising a heating roller. At this time, the undrawn yarn may be drawn after being wound once, or may be directly drawn without winding the undrawn yarn once. [0022] The woven screen mesh is the next support of the present invention
The thing is explained. The woven density of the screen gauze fabric of the present invention is 50 to 300 woven / inch (that is, 50 to 300 mesh) plain weave or twill weave, depending on the use as the heat-sensitive stencil base paper, that is, the ink supply amount. An appropriate weaving density and weaving structure may be selected in accordance with the pattern and the line width of the picture. Usually, it is preferably 80 to 250 pieces / inch. It may be a at least one of core-sheath type composite fibers of the warp or weft yarns constituting the screen mesh cloth fabrics as a support of the present invention, the warp yarn and the weft yarn are both core-sheath type composite fibers, the warp yarn is known Weft yarn with polyester fiber
The core-sheath composite fiber and the warp yarn may be a core-sheath composite fiber, and the weft may be a conventionally known polyester fiber. The purpose of the present invention to prevent static electricity is to prevent the adhesion of fine foreign substances by attaching an antistatic agent to the screen gauze surface. In addition, it is necessary to take care not to damage the thermal head when drilling with a thermal head or the like. For example, if only antistatic properties are imparted to the base paper, an antistatic agent may be attached to the surface of the film. However, heat-sensitive stencil printing paper is made from the film surface side with a thermal head or the like.
The film is melted with a high energy density during perforation. At this time, the attached antistatic agent also melts and decomposes, and a part thereof evaporates and sublimates. These gases cause contamination and damage to the thermal head. In particular, when an ionic substance is contained, the degree of damage becomes significant.
In the present invention, the above-described problem can be avoided or reduced by only performing the antistatic treatment on the surface of the screen gauze. That is, the heat transfer to the screen gauze at the time of perforation is slight, and the melting and decomposition of the antistatic agent hardly occur. Therefore, there is an advantage that not only there is no danger of damage to the thermal head, but also the effect of preventing static electricity is maintained. Therefore, it is necessary to carry out the process of attaching the antistatic agent to the screen gauze before laminating and bonding to the film. In the present invention, the kind of the antistatic agent is not particularly limited, but it is preferable to use a nonionic surfactant since the generation of metal ions during plate making is small. Such nonionic surfactants include, for example, polyoxyethylene fatty acid esters, polyoxyethylene alkyl ethers, polyesters from polyvinyl acetate and maleic anhydride, and the like. Further, an antistatic agent containing a polyoxyethylene fatty acid ester is particularly preferable from the viewpoint of heat adhesion to a film. The antistatic agent can be used as a single component or a combination of plural components in a 0.1 to 5% aqueous solution. Further, an emulsifier, a crosslinking agent and the like may be used in combination. The adhesion amount of the antistatic agent to the screen gauze is about 0.001 to 0.1% by weight based on the weight of the screen gauze, depending on the type of the antistatic agent.
When the content is less than 0.001% by weight, there is a problem that the effect of preventing static electricity is small, and fine foreign substances and the like are easily attached. on the other hand,
If it is 0.1% by weight or more, the lamination thermal adhesiveness to the film may decrease. The specific resistance of the untreated screen gauze is about 1 × 1
0 is about ¹⁴ Omega · cm, significantly electrostatic charge due to friction or peeling, easily adheres minute foreign matter. In order to prevent the attachment of fine foreign matter, the specific resistance should be 1 × 10 ¹⁰ Ω · cm
It is preferable to set the following. The process of attaching the antistatic agent to the screen gauze removes scum, dirt, etc. by scouring.
It is preferred to carry out the washing after the washing, but it may be applied in any step after scouring until the film is thermally bonded to the film. Also, the method of attachment is immersion,
Any method such as spraying and coating may be used, and it is preferable to uniformly adhere to the surface of the screen gauze. The screen gauze woven using conjugate fibers is washed with a nonionic or anionic surfactant aqueous solution at 60 to 90 ° C. in the scouring step, washed with water, and then heated to 170 to 230 ° C. in the setting step. 2-10Kg / 5cm
To a predetermined thickness and mesh number of 0 to 1
Set to 0% extension. The setting process of the screen gauze is
One step or two or more steps may be used. It is particularly preferable that the setting step is performed in two or more steps, and scouring is performed after setting the first step, since wrinkles in the scouring step can be prevented. Further, it is not necessary to apply an adhesive to the film surface and / or the screen gauze surface as in the conventional method, which greatly reduces the perforation sensitivity which has been a problem by applying the adhesive. Not only can we improve,
Eliminates defects such as film thickening, wrinkles, and wrinkles due to uneven application of adhesive, and eliminates problems due to adhesion of dust and dirt due to the attachment of an antistatic agent. It is made possible. For the purpose of preventing static electricity, the friction voltage of the screen gauze was measured under the conditions of 20 ° C. and 30% RH according to JIS L1094 [Electrification test method for woven and knitted fabrics]. Further, the surface of the screen gauze is cotton cloth (Kanakin No. 3, 4-fold) at 20 ° C. and 30% RH.
Rub 15 times evenly to write a circle with a pressure of about 500 g, and immediately after the rubbing, bring the surface of the screen gauze to a distance of 1 cm to the ash of cigarette (dispersing 1.5 g of ash uniformly in 10 cm x 10 cm). After standing still for 5 seconds, the degree of adhesion of fine foreign matter was observed. The melting point of the polyester of the core component and the sheath component of the present invention was determined by taking 10 mg of the powder of the polymer to be used and raising the temperature at 10 ° C./min using a differential scanning calorimeter (manufactured by PerkinElmer: DSC-7 type). The melting point Tm (° C.) was determined by processing the endothermic peak accompanying the melting that occurred during the heating process with a data processing system manufactured by PerkinElmer. The breaking strength and elongation at break of the screen gauze of the present invention were measured using a constant-speed tension type tensile tester according to JIS 1068.
According to the labeled strip method described in -1964, sample width 5
cm, gripping interval 20 cm, and pulling speed 20 cm / min, and are the average values of 5 repetitions. According to JIS K6854, both sides of the support and the polyester film were reinforced with an adhesive tape and subjected to a T-type peel test with a sample width of 25 mm in accordance with JIS K6854. It is obtained from the strength. Next, the present invention will be described in detail with reference to examples. Example 1 Polyethylene terephthalate having an intrinsic viscosity [η] of 0.65 and a melting point of 255 ° C. measured at 25 ° C. using orthochlorophenol as a solvent was used as a core component, and 25 mol% of isophthalic acid was added as an acid component during polymerization of polyethylene terephthalate. Intrinsic viscosity [η] is 0.65 and melting point is 1
Concentric core-sheath composite fibers (core: sheath cross-sectional area ratio = 70:30) unstretched yarn was obtained by using a composite spinning machine with copolymerized polyethylene terephthalate at 90 ° C as a sheath component. The undrawn yarn was drawn at a draw ratio of 4 by a drawing machine having a heating roller and heat set to obtain a drawn multifilament A having 30 deniers and 12 filaments. The yarn properties of the drawn multifilament A were such that the breaking strength was 5 g / d and the breaking elongation was 40.
%, And the dry heat shrinkage at 160 ° C. was 18%. The drawn multifilament A was twisted at 1000 turns / m using a double twister. Next, a 100-mesh plain weave screen was woven using the drawn multifilament A as a warp yarn and a weft yarn to prepare a greige machine. 4% in the vertical direction and 1% in the horizontal direction
Heat treatment (normal presetting) was continuously performed at 180 ° C. for 30 seconds while extending, and the screen gauze was rapidly cooled by blowing cold air of 30 ° C. or less. Next, this screen gauze is scoured by a conventional method and washed with water, and then a 1% nonionic antistatic agent composed of sorbitan laurate (EO) _{20 is} used.
The screen gauze was immersed in an aqueous solution to adhere an antistatic agent to the screen gauze in a solid content of 0.06% by weight. The screen gauze is further heat-treated (normal finishing set) at 210 ° C. for 30 seconds while being stretched by 0.2% in the vertical direction and 0.1% in the horizontal direction on a spreading type cloth setter, and then 30 ° C. The screen gauze is rapidly cooled by blowing the following cold air, and the weave density is 100
A screen gauze of book / inch and a thickness of 80 μm was obtained. The breaking strength of this screen gauze was 18 kg / 5 cm, and the breaking elongation was 15%. This screen gauze is laminated as a heat-sensitive stencil support with a film of polyethylene terephthalate having a thickness of 2 μm, and heated with a heating roller at 130 ° C. by using a metal mirror heating roller and a calender roller comprising a hard rubber roller.
Heat bonding was performed with a cylinder pressure of 5 kgf / cm ² and a processing time of about 1 second to obtain a heat-sensitive stencil sheet. The heat-sensitive stencil sheet had very small floating and wrinkles, a peel strength of 50 g / 25 mm, and was excellent in adhesiveness. In addition, a triboelectric voltage was 200 volts, and no adhesion of fine foreign matter was observed in an adhesion test using tobacco ash, and the heat-sensitive stencil sheet had excellent antistatic properties. Using this heat-sensitive stencil sheet, a 6-point size character and solid portion are made by a thermal copying and printing machine using a 400 DPI thermal head.
When the printing was performed, a very clear printed matter without blurring or shading was obtained. Comparative Example 1 Polyethylene terephthalate having an intrinsic viscosity [η] of 0.65 and a melting point of 255 ° C. was spun using a single-component spinning machine, and the obtained undrawn yarn was drawn using a drawing machine having a heating roller. The film was drawn at a draw ratio of 4 and heat set to obtain a drawn multifilament B having 30 deniers and 12 filaments. The yarn physical properties were a breaking strength of 5.2 g / d, a breaking elongation of 40%, and a dry heat shrinkage at 160 ° C. of 12%. Using a double twister for this drawn multifilament B, 1000 turns /
m of twist. Next, a plain mesh screen gauze of 100 mesh was woven by using the drawn multifilament B as a warp yarn and a weft yarn to prepare a greige machine. 4% in the vertical direction and 1% in the horizontal direction
While elongating, it was continuously heat-treated (normal preset) at 180 ° C. for 30 seconds and cooled. Next, the screen gauze is scoured and washed with a conventional method, and then stretched by 0.2% in the vertical direction and 0.1% in the horizontal direction with a spreadable cloth setter.
Heat treatment (normal finishing set) was continuously performed at 0 ° C. for 30 seconds to obtain a screen gauze having a weave density of 100 / inch and a thickness of 85 μm. The breaking strength of this screen gauze is 25K
g / 5 cm, elongation at break was 20%. The screen gauze was coated with a vinyl acetate adhesive and laminated with a film of polyethylene terephthalate having a thickness of 2 μm, and dried and solidified in a drier to obtain a heat-sensitive stencil sheet. The heat-sensitive stencil sheet has a lot of wrinkles, wrinkles, and a low yield, and a peel strength of 45 g / 2.
5 mm. Also, the friction band voltage is 5000 volts,
Furthermore, in the adhesion test using tobacco ash, remarkable fine foreign matter was observed. Using the heat-sensitive stencil printing paper, a 6-point size character and solid portion are made by a thermal copying machine using a thermal head of 400 DPI.
When the printing was performed, it was an unclear printed matter in which many blurs and unevenness in density were observed. The heat-sensitive stencil sheet of the present invention does not have an adhesive applied thereto, and substantially no adhesive is present in the opening portion of the screen gauze covered with the film. Therefore, when making a heat-perforated stencil with a thermal head, etc., the residue remaining in the perforated portion is extremely small, and since it has antistatic properties, the adhesion of fine foreign substances is extremely small, and the ink permeability is excellent. Therefore, it is particularly suitable for precision printing. Further, since the solvent resistance of the heat bonding portion is excellent, the bonding surface is not affected by the ink and the ink solvent and the like, and the durability is excellent.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-5-193284 (JP, A) JP-A-4-235094 (JP, A) JP-A-4-232789 (JP, A) JP-A-4-234 27591 (JP, A) JP-A-4-78589 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B41N 1/24 102

Claims (1)

(57) [Claim 1] A polyester film having a thickness of 5 μm or less, and a sheath component to which an antistatic agent is attached is a low melting point polyester.
Base paper for heat-sensitive stencil printing obtained by laminating and thermally bonding a screen gauze fabric having thermal adhesiveness made of core-sheath type composite fiber which is a tellurium.