JPH0427591A - Porous thin leaf sheet for thermal stencil printing - Google Patents

Abstract

PURPOSE:To obtain high image visualization by specifying basis weight, density, Gurley's stiffness and intrinsic surface resistance. CONSTITUTION:A curing agent such as melamine resin, epoxy resin, urethane resin, modified polyamide resin, dithiardehyde starch, polyamide or epichlorohydrin resin and an antistatic agent of non-ion ester acrylate compound or non-ion polyoxyethylene are applied simultaneously. In this case, the quality design is such that the basis weight is 8.0 to 12.0g/m<2>, density is 0.18 to 0.24g/cm<2>, Gurley's stiffness is 15mg or higher and intrinsic surface resistance is 9.0 to 10<9>OMEGA or lower under an environmental condition of 20 deg.C and 65% RH. In addition, 0.4 to 3.0g/m<2> of curing agent in terms of solid component and 0.02 to 0.10g/m<2> or higher of antistatic agent are added. Thus an improved image quality is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a porous thin paper used as a heat-sensitive printing base paper to be subjected to a plate-making method using a writing perforation method using a thermal head.

[Conventional technology]

As a porous thin paper used for heat-sensitive stencil printing base paper,
Up until now, washi paper made of 100% natural fibers such as Manila hemp has been the mainstream because it has good ink permeability and can produce clear printed images.

However, since natural fibers always have unique binding fibers, when printing with heat-sensitive stencil printing base paper using these washi papers, a defect of about 1 m2 in size (so-called white spots) will appear in the solid printing area. It is not desirable because it is sporadic. As shown in Japanese Patent Application Laid-Open No. 60-217197, the number of white strips is 200 for Japanese paper made of 100% Manila hemp fiber.
It is stated that the number of pieces per 20 Onf.

This quality defect of white spots is caused by the increasing number of occasions in which simple stencil printing machines are used in modern offices to stencil-print photo manuscripts, and users are demanding higher image quality. This is becoming very disadvantageous in the current situation where the number of

Recently, 10 synthetic chemical fibers such as polyester have been introduced.
Porous tissue paper made from 100% natural fibers has been developed and commercialized one after another, and although the printing density is inferior to Japanese paper made from 100% natural fibers, the image quality is good as there are no white spots due to binding fibers. It meets user quality demands for high image quality, and has better printing durability than Japanese paper made of 100% natural fibers, so it is becoming the mainstream porous thin paper for heat-sensitive stencil printing. In addition, regarding print density, users have recently begun to request a print density that is slightly lower than the conventional print density, as it is said that high print density causes severe show-through on the receiver paper. Inferiority now doesn't matter as much as it used to.

However, unresolved issues remain in order for porous tissue paper for heat-sensitive stencil printing made of 100% synthetic chemical fibers to meet the quality demands of end users in the future.

[Problem to be solved by the invention]

Conventional porous thin paper for heat-sensitive stencil printing made of 100% synthetic chemical fibers has a problem in transportability in a plate-making printing machine because of its weak stiffness. In other words, after the heat-sensitive stencil printing base paper is made into a plate, it is cut and wrapped around a rotary drum because it is not sturdy enough to cause wrinkles, and as a result, the resulting printed matter retains the wrinkles from the plate making. A problem arises in which it appears.

Furthermore, since the static electricity of the porous thin paper itself is quite strong, the base paper is drawn to the rolls during transportation in the plate-making printing press, causing wrinkles and similar problems.

In JP-A-2-30593, in order to prevent the porous thin paper from sticking to the thermal head during plate making, the quality of the porous thin paper is improved so that it has a stiffness equal to or higher than the Gurley stiffness s, orng. However, it is not mentioned at all that the strength of the static electricity of the porous thin paper is also a factor in hindering transport performance during plate making.

The present invention was devised to solve the above-mentioned drawbacks of heat-sensitive stencil printing-like porous tissue paper, and it has good image quality and print density, good printing durability, strong stiffness, and no static electricity. This is a porous thin paper for heat-sensitive stencil printing which has excellent hard compatibility and has no problems with conveyance during plate making because of its low content.

[Means to solve the problem]

The porous thin paper for heat-sensitive stencil printing of the present invention has a basis weight of 8.
O~12.0g/rd, density 0.18~0゜24g
/an3, Gurley stiffness 15mg or more, surface specific resistance 2
9. Under an environment of 0°C and 65%RH. It is 0 to 10 9 Ω or less.

The reason why the quality design of the porous thin paper for heat-sensitive stencil printing of the present invention was set within the above numerical range will be described. Basis weight 8
．． If it is less than 0 g/m2, the strength of the porous thin paper becomes weak, the printing durability becomes poor, and the thickness becomes thin and stiffness becomes weak, so that wrinkles are likely to occur during transportation during plate making, which is not preferable. On the other hand, if the basis weight is greater than 12, Og/m2, the amount of fibers per unit area of the porous thin paper will increase, which will impede the passage of ink, resulting in a low print density, which is not preferable. If the density is 0.18 g/cm" or less, it is necessary to weaken the web pressing pressure in the Yankee dryer during paper making, so porous thin paper produced under these production conditions will have a weak surface strength. , it is undesirable because the fibers on the surface tend to fall off, causing quality defects that stain the inside of the hardware during platemaking.On the other hand, the density is 0.24.
If it is larger than g/cm3, the thickness of the porous thin paper becomes excessively thin and the ink retention power is lost, and the ink accumulates on the porous thin paper, reducing its strength and reducing printing durability. This is undesirable because it weakens and causes wrinkles during printing.

If the stiffness has a Gurley stiffness of 15 mg or more, wrinkles will not occur during plate making, but if it is less than 15 mg, the stiffness is insufficient and the rate of plate making wrinkles increases, which is not preferable. The surface resistivity is 9 at 20°C and 65%RH.
．． If it is 0XIO'Ω or less, it can be said that the conductivity treatment has been carried out sufficiently, and it is possible to avoid inducing static electricity during plate making, which causes wrinkles. If it exceeds 9.0XIO'Ω, it cannot be said that the conductive treatment is sufficient, and static electricity is induced during plate making, which increases the possibility of wrinkles, which is not preferable.

The porous thin paper made of 100% synthetic chemical fibers before the invention was composite polyester binder fibers with a fineness of 2.0 denier or less and a fiber length of 5 mm or more (sheath melting point 110-120
30 to 70% of polyester fibers with a core melting point of 250 to 260 degrees Celsius, a fineness of 0.1 to 2.0 denier, and a fiber length of 3 to 5 mm are mixed as paper stock, and the basis weight is 8. ．．
The paper was made using a circular mesh paper machine so that the paper had a density of 0.18 to 0.24 g/3, dried at a Yankee dryer, and wound up as a product. When used as porous thin paper for heat-sensitive stencil printing base paper, printing durability is good due to sufficient water resistance, and the number of fibers per unit area and pore diameter are appropriately adjusted, resulting in a well-balanced print density and resolution. Although the quality is good, the porous thin paper itself is not stiff and has strong static electricity, so it has the disadvantage of wrinkles during plate making.

Therefore, the present invention was devised, in which a curing agent such as melamine resin, epoxy resin, urethane resin, modified polyamide resin, disialdehyde starch, polyamide, epichlorohydrin resin, etc. is added to the above-mentioned porous tissue paper by an external addition method. This is a porous thin paper coated with a nonionic acrylic acid ester polymer or nonionic polyoxyethylene antistatic agent.

The amount of hardening agent to be applied is 0.4 g/r1 or more in terms of solid content to be sufficiently effective in strengthening the waist. That is, a stiffness with a Gurley stiffness of 15 or more can be obtained, and the problem of conveyance wrinkles during plate making can be solved. A sufficient firmness-enhancing effect can be obtained when the hardening agent is applied in an amount of solid content of 0.4 g/m2 or more, but if the applied amount is significantly larger than this, for example, 3.0 g/rd, the hardening agent resin may cause cross-section of the fibers. This is undesirable because it has a strong tendency to block the area, impairs ink permeability, and reduces print density. The amount of antistatic agent applied is 0.02g/r solid content.
A sufficient conductive treatment effect can be obtained at If or higher. That is, 20
Surface resistivity 9.0 x 109Ω under ℃65%RH environment
The following measurement values can be obtained, and the problem of transport wrinkles caused by static electricity during plate making can be solved. The amount of antistatic agent applied is 0 solids.
．． A sufficient chargeability treatment effect can be obtained with a coating amount of 0.02 g/rd or more, but a coating amount significantly larger than this, for example, 0.10 g/rd
If the level exceeds m2, the hygroscopicity becomes excessively high, which weakens the stiffness of the porous thin paper and causes plate-making wrinkles, and also reduces strength and printing durability, which is not preferable.

Among these hardening agents, the one that is most effective in strengthening the waist is the hardening agent for melamine resin. However, in the case of melamine resin, after adding the melamine resin during liquid preparation, 5 to 15% of the reactive catalyst (solid/solid) based on the melamine resin and 30 to 40% (solid/solid) of the formalin scavenger are added. There is a need. When a curing agent such as this melamine resin is externally added to porous thin paper and dried, the bonds between the fibers of the porous thin paper are strengthened, the elastic modulus is increased, and the paper becomes stiffer.

When a nonionic acrylic acid ester polymer or a nonionic polyoxyethylene-based antistatic agent is externally added to porous thin paper and dried, the porous thin paper becomes more hygroscopic and has better conductivity, so it is not necessary for conductive treatment. Effects can be obtained. The reason for specifying nonionic and ionic here is that if it is nonionic when mixed with a curing agent, there is no risk of agglomeration regardless of the ionicity of the curing agent.

We will also discuss the effect on image quality of externally adding a hardening agent to porous thin paper.

By externally adding a small amount of resin to the surface of the fibers of porous tissue paper, the fiber intersections are bonded more strongly than before externally adding, but the amount of adhesion is small, about 0.4 to 3.0 g/m2. Since the level does not go so far as to form a resin film at the fiber intersections, ink permeability will not be deteriorated. For this reason, by externally adding a curing agent to porous tissue paper, the effect of increasing stiffness can be increased without deteriorating the image quality at all.

In order to externally add a curing agent and an antistatic agent to porous thin paper, there is a method of drying the porous thin paper once with a Yankee dryer and then impregnating it with a size press or tab size. Furthermore, in order to perform production more efficiently than such conventional production techniques, a method of spraying the porous tissue paper with a spray device or a transfer roll just before entering the Yankee dryer or at the location where it is being dried in the Yankee dryer is proposed. A method in which the liquid is applied by means of water is preferred.

〔Example〕

EXAMPLES The present invention will be explained in detail below with reference to Examples, but the present invention is not limited to these Examples. In addition, the following characteristics were graded and evaluated as follows.

1) Print density O Good, △ Normal, × Not good 2) Resolution ○ Good, △ Average, × Not good 3) Printing durability The number of sheets that can continuously obtain good prints without thickening or stretching is "up to ~" It is shown as follows.

4) Plate making wrinkles caused by stiffness ○ None, × Yes 5) Plate making wrinkles caused by static electricity 0 None, × Yes The physical properties of porous tissue paper are measured by basis weight, density, tensile strength, and water resistance. The Gurley stiffness was determined according to JIS L1085 and JIS L1079. The surface resistivity was measured using a high resistance meter manufactured by Yokogawa Hewlett-Packard.

Examples 1 to 3 Composite polyester binder fiber with fineness of 2 denier and fiber length of 5 mm (core melting point 250-260°C, sheath melting point 1)
10-120℃) 60%, fineness 0.5 denier fiber length 5
20% polyester fiber with a fineness of 0.3 mm, 10% polyester fiber with a fiber length of 5 mm, a fineness of 0.3 denier. 10% of 1-denier polyester fibers with a fiber length of 3 nm were mixed as paper stock, and the basis weight was 10. Make paper equivalent to g/m2.

A mixed solution of a melamine resin curing agent and a nonionic acrylic acid ester polymer antistatic agent is sprayed onto this porous thin paper web before being placed in a Yankee dryer using a spray device. The coating amount is 0.4g solid content of melamine resin curing agent.
/rr1 or more, and the concentration of the mixed liquid and the spray amount are adjusted so that the solid content of the antistatic agent of the nonionic acrylic ester polymer is 0.02 g/rr1 or more. The paper is then dried using a Yankee dryer and rolled up.

To prepare the mixed solution, add 10 parts of melamine resin curing agent (solid),
1 part (solid) of a reactive catalyst, 3 parts (solid) of a formalin scavenger, and 0.5 part (solid) of an antistatic agent of a nonionic acrylic acid ester polymer are dissolved in water.

A 2μ thermoplastic polyester film was bonded to the porous thin paper thus produced using a vinyl acetate adhesive to produce a base paper for heat-sensitive stencil printing, and plate printing was performed.

Table 1 shows the contents of the paper manufacturing side of the porous thin paper for heat-sensitive stencil printing.

Table 2 shows the experimental results for each papermaking example, including the physical properties of porous thin paper (vertical tensile strength, vertical water resistance, Gurley stiffness, surface resistivity) and plate-making printing properties (print density, resolution, printing durability,
Indicates plate-making wrinkles caused by lower back pressure and plate-making wrinkles caused by static electricity.

Comparative Example 1 Porous thin paper was made in the same manner as Examples 1 to 3 except that no curing agent and antistatic agent were sprayed.

Comparative Example 2 A porous thin paper was made in the same manner as in Examples 1 to 3, except that the amount of the melamine resin curing agent was 0.3 g/m2 and the nonionic acrylic acid ester polymer was 1015 g/m2.

Comparative Examples 3 to 5 The amount of melamine resin curing agent deposited was 0.4.2° and 8.3°, respectively.
．． 6 g/d, porous thin paper was made in the same manner as in Examples 1 to 3, except that the nonionic acrylic acid ester polymer was not sprayed.

Comparative Examples 6 to 8 No melamine resin curing agent was sprayed, and the amount of nonionic acrylic acid ester polymer deposited was 0.0 and 0.0, respectively.
09. Porous thin paper was made in the same manner as Examples 1 to 3 except that the amount was 0.14 g/i.

[Effects of the invention] Conventional porous thin paper has a fineness of 2. Composite polyester binder fiber with θ denier or less and fiber length of 5+ nm or more (sheath melting point 110-120°C, core melting point 250-260°C)
30 to 70% of polyester fibers with a fineness of 0.1 to 2.0 denier and a fiber length of 3 to 5 denier are mixed as paper stock, and a paper layer is formed using a cylinder paper machine, and a Yankee dryer is used to form a paper layer. Dry and have a basis weight of 8.0 to 12.0 g/rr? , density 0
．． It was made into paper with a weight of 18-0°24g/m2. When a 2μ polyester film is laminated to this and used as a base paper for heat-sensitive stencil printing, it has sufficient water resistance, so printing durability is good, and the pore size can be controlled appropriately, so it is possible to obtain good quality in both print density and resolution. However, there was a quality defect in that wrinkles occurred during transportation due to the weakness of the plate and the strength of static electricity.

According to the present invention, by externally adding a curing agent such as melamine resin, epoxy resin, or urethane resin, and a nonionic acrylic acid ester polymer or nonionic polyoxyethylene-based antistatic agent to porous thin paper, porous By strengthening the binding force at fiber intersections and improving the elastic modulus of the thin paper, it strengthens the stiffness, and conductive treatment reduces the generation of static electricity. As a result, it is possible to prevent paper transport wrinkles caused by the weakness of conventional layers and static electricity during plate making, and is used for heat-sensitive stencil printing base paper that has excellent printing durability, image quality (print density, resolution), and transportability. It is possible to provide a porous thin paper that is

Claims (3)

[Claims] (1) Basis weight 8.0-12.0g/m^2, density 0.18
0.24g/m^3, Gurley stiffness of 15mg or more, surface resistivity 9.0x10^9 in an environment of 20°C and 65%RH
A porous thin paper for heat-sensitive stencil printing, characterized in that it has a resistance of Ω or less. (2) The porous thin paper for heat-sensitive stencil printing according to claim 1, characterized in that it contains a curing agent of 0.4 to 3.0 g/m^2. (3) The porous thin paper for heat-sensitive stencil printing according to claim 1 or 2, which contains an antistatic agent at an amount of 0.02 to 0.10 g/m^2.