JP2003278098A - Pseud-bondable recording paper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide pseud-bondable recording paper that causes no toner blocking, when the paper is treated with a heat-roll type non-impact high-speed laser beam printer and shows good NIP fitness. <P>SOLUTION: The recording paper is produced by forming a pseud-bondable, pressure-sensitive adhesive layer on the surface of a base sheet having a density of ≤0.7 g/cm<SP>3</SP>. When the recording paper is passed through between a pair of the rolls, a heatable non-elastic roll and an elastic roll at 180°C, at a pressure of 2 kg/cm<SP>2</SP>at a speed of 5 m/min., the change of the surface temperature of the passing recording paper is monitored with a non-contact type infrared surface thermometer. When the temperature change is approximated to the following formula (1): T=T<SB>a</SB>+(T<SB>0</SB>-T<SB>a</SB>)e<SP>-</SP>A<SP>t</SP>the constant A is ≥1.20. (in which A is a constant; T is a surface temperature; T<SB>a</SB>is an atmospheric temperature (23°C); T<SB>0</SB>is the temperature immediately after passing the roll (°C); T is a elapsed time in second; and e is the base of NL). <P>COPYRIGHT: (C)2004,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-roll type non-impact high-speed laser beam printer (NI).
The present invention relates to a recording sheet having a pseudo-adhesive recording surface, which is excellent in printability by P), does not adhere in a normal state, and removably adheres when pressed under certain conditions. [0002] Conventionally, various kinds of information that need to be concealed or concealed on the surface of a layer having pseudo-adhesive performance of a base sheet provided with a pressure-sensitive adhesive composition layer having pseudo-adhesive performance. After printing / printing, etc., the layers are opposed to each other and pressurized and pseudo-adhered to form an information concealable sheet that can be peeled off when necessary, and is used for confidential postcards and the like. I have. Usually, these pseudo-adhesive recording papers are printed with fixed information by offset printing or the like on the pseudo-adhesive layer and then subjected to form processing, and variable information is printed by various printers. As these printers, a heat roll type NIP, a flash type NIP, an ink jet printer, and the like are used. Among them, printing is often performed by a heat roll type NIP. In the heat roll type NIP, a sheet is usually introduced in a folded state, passed through a transport path, and set again in a folded state. During this time, the toner is transferred and the toner is fixed on the sheet by heat and pressure. However, depending on the type of the sheet, the toner adheres to the opposite surface when the sheet is folded again (toner blocking). Sometimes occurred. If toner blocking occurs, information may be transferred to the opposite side when the fold is released, or in the worst case, the paper surface may be damaged. Is required for paper. [0004] The above-mentioned trouble of toner blocking is caused by
Compared to high-quality recording paper, it often occurs with pseudo-adhesive recording paper used for confidential postcards and the like. However, in the related art, since the toner blocking has to be determined by actually processing with NIP, the method is complicated. Therefore, a method capable of easily evaluating the toner blocking has been required. Further, there has been a need for a recording paper which can be pseudo-adhered without causing toner blocking. The inventors of the present invention have investigated the cause of toner blocking. As a result, the toner blocking increases the paper temperature when the toner is fixed on the paper by the NIP process. It has been found that this occurs when the sheet temperature does not sufficiently fall below the fusion temperature of the toner within the time until the sheet is folded again. Therefore, as a result of further intensive studies on the method of evaluating the temperature of the sheet, or the method of evaluating the heat radiation, a pair of pressurizable rolls consisting of a heatable inelastic roll and an elastic roll were heated and heated. By measuring the change in the surface temperature of the recording paper after passing when the recording paper is passed under a constant pressurized condition, and obtaining a constant A in a constant approximate expression,
In addition to elucidating that it is possible to evaluate the heat radiation property of the recording paper, if A in the formula is 1.20 or more, NI
The present inventors have found that the recording paper can be evaluated as a pseudo-adhesive recording sheet excellent in P suitability, and arrived at the present invention. Accordingly, an object of the present invention is to provide a pseudo-adhesive recording sheet excellent in NIP suitability, which does not cause the toner blocking described above. [0006] The above objects of the present invention are as follows.
A recording sheet having a pressure-sensitive adhesive layer provided on at least one side of a substrate sheet, wherein the density of the substrate sheet is 0.7 g / cm ^3.
In addition to the following, a pair of pressurizable rolls composed of a heatable non-elastic roll and an elastic roll,
When the recording paper is passed at a speed of 5 m / min under a heating and pressurizing condition of 180 ° C. and 2 kg / cm ^{2 in} an environment of% RH, a change in the surface temperature of the recording paper after passing is not affected. Measured using a contact-type infrared surface temperature measuring device, the following (1)
This was achieved by a pseudo-adhesive recording sheet, wherein the constant A obtained by approximating the equation was 1.20 or more. T = T _a + (T ₀ −T _a ) e− ^At (1) The present invention will be described in more detail below. The following equation (1) used in the present invention is a general equation that is determined by the fact that the temperature change of the heated sheet is proportional to the temperature difference from the ambient temperature, and the constant A takes a value specific to the sheet. ^{_{T = T a + (T 0}} -T a) e -At (1) A = Constant T = surface temperature (℃) _{T a} = ambient temperature (23 ℃) _{T 0} = roll immediately after passing Temperature (° C.) t = Elapsed time (seconds) e = base of natural logarithm The larger the value of the constant A, the larger the value, the greater the temperature change of the paper, that is, the better the heat radiation property and the easier the paper cools. I have. [0008] The substrate sheet used in the present invention is not particularly limited, but is mainly made of wood pulp.
Synthetic fibers and inorganic fibers are blended as necessary, and fillers, paper strength agents, sizing agents, yield improvers, etc. are appropriately added,
It is preferable to use a base sheet obtained by papermaking with a fourdrinier or twin wire papermaking machine, applying a sizing agent or a surface strength improver by a size press, drying, and smoothing with a calender. The density of the base sheet depends on the type of pulp and the degree of beating, the amount of internal additives, raw materials such as internal additives,
The papermaking conditions such as wet pressing and calendering are appropriately adjusted, and adjusted to 0.7 g / cm ³ or less. By setting the density of the base sheet to 0.7 g / cm ³ or less as described above, the above constant increases, and the toner blocking property is improved. In the present invention, as a base emulsion used in the pseudo-adhesive pressure-sensitive adhesive composition, natural rubber latex obtained by polymerizing an acrylic monomer such as methyl methacrylate, styrene-butadiene copolymer latex, ethylene-vinyl acetate Known emulsions such as a resin emulsion and an acrylic resin emulsion can be used alone or in combination. In the present invention, the above resin emulsion 100
To adjust the adhesive strength at the time of press bonding to the parts by weight (dry parts by weight, hereinafter the same), and as a measure against blocking at the time of paper winding or stacking, fine particles having an average particle diameter of 1 to 30 μm are 50 to 350 μm. It is preferable to add 100 parts by weight, especially 100 to 250 parts by weight. When the average particle diameter is less than 1 μm, there is a problem that blocking becomes easy when the average particle diameter is less than 1 μm, and when the average particle diameter exceeds 30 μm, the particles easily fall off from the coating layer. Incidentally, the average particle diameter referred to here generally means the average value of the size of one particle. For example, fine particles such as silica form a group and behave as if they are one particle. If you indicate
It means the average size of this group (secondary particles). Further, fine particles of 1 to 30 μm are formed in the resin emulsion 10.
When the amount is less than 50 parts by weight with respect to 0 parts by weight, the re-peeling performance is inferior. On the other hand, if it exceeds 350 parts by weight, it becomes difficult to obtain an adhesive force at the time of press bonding, and it is easily peeled off when processed into a confidential postcard or the like. The fine particles used in the pressure-sensitive adhesive composition of the present invention may be either organic or inorganic particles. For example, organic particles are starch particles, cellulose fine powder, melamine-based resin particles, urea-based resin particles, styrene-based resin particles, among known fine particles such as acrylic resin particles, and inorganic particles, silica, It can be appropriately selected from known fine particles such as kaolin, talc, calcium carbonate, aluminum hydroxide, zinc oxide, and titanium oxide. In addition, the pressure-sensitive adhesive composition includes styrene-butadiene latex, an acrylic resin-based emulsion, a vinyl acetate resin-based emulsion, and a urethane resin in order to prevent the pressure-sensitive adhesive layer from falling off during printing or NIP processing. It is preferable to add 5 to 30 parts by weight of a binder component such as a system emulsion. The pressure-sensitive adhesive composition of the present invention may contain, if necessary, an antistatic agent, a surfactant, an antifoaming agent, a dispersant, a viscosity modifier, an ultraviolet absorber, an antioxidant, various dyes, etc. Can be added. In the pseudo-adhesive recording paper of the present invention, the coating amount of the pressure-sensitive adhesive composition,
Usually, it is ^{2 to} 10 g / m ² (dry weight), more preferably 3 to 8 g / m ² . When the coating amount is less than 2 g / m ² , the adhesiveness cannot be sufficiently exhibited. In addition, 10 g / m ²
If it exceeds, the adhesive strength becomes too high and it is uneconomical. The application of the pressure-sensitive adhesive composition to the substrate sheet is performed in a conventionally known coating apparatus such as a blade coater, an air knife coater, a roll coater, a kiss coater, a bar coater, a curtain coater, a gravure coater or a comma coater. The coating method can be appropriately selected from the above, but a contour coating method using an air knife coater, curtain coater, comma coater, or the like is particularly preferable. Since the recording paper of the present invention has excellent heat radiation performance, the recording paper quickly drops to a temperature sufficiently lower than the fusion temperature of the toner even when subjected to NIP processing. This prevents the occurrence of toner blocking, and is therefore suitable for mass mailing such as direct mail, especially for mass-use postcards where production efficiency is important. EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto. <Heat dissipation evaluation test> Under an environment of 23 ° C. and 50% RH, a pair of pressurizable rolls composed of a heatable inelastic roll and an elastic roll were pressed at 180 ° C. under a pressure of ² kg / cm ^2. A non-contact type infrared surface temperature measuring device (Handy Thermo TVS-) is used to measure the change in the surface temperature of the recording paper after passing through the A4-size recording paper at a speed of 5 m / min.
110, Nippon Avionics Co., Ltd.), and the temperature change was approximated by the following equation (1) to obtain a constant A, and the heat radiation of the recording paper was evaluated. ^{_{T = T a + (T 0}} -T a) e -At (1) A = Constant T = surface temperature (℃) _{T a} = ambient temperature (23 ℃) _{T 0} = roll immediately after passing Temperature (° C.) t = Elapsed time (seconds) e = base of natural logarithm <Toner blocking> The recording paper is transferred to a heat roll type high-speed NIP (Inf manufactured by IBM Japan, Ltd.).
o Print 3900) to evaluate the presence or absence of toner blocking during continuous processing. Embodiment 1 FIG. 90 parts by weight of hardwood bleached kraft pulp (freeness 450 mlc.sf), softwood bleached kraft pulp (freeness 500 mlc.sf) 10
Parts by weight and 5 parts by weight of talc, and a slurry containing 0.4 parts by weight of an internal zizing agent, 1.0 parts by weight of aluminum sulfate, and 50 ppm of a retention aid was adjusted. papermaking, using size press, a liquid obtained by adding a surface sizing agent 0.6 weight percent oxidized starch 10 wt% and coated to a per side ^{2.5g / m 2, 90g / m} 2 groups A material sheet was obtained.
In addition, the density of this sheet was adjusted to 0.66 g / cm ³ by adjusting wet press and calendar conditions. On the other hand, acrylic-modified natural rubber latex 1
00 parts by weight, starch particles 12 having an average particle size of 14 μm
0 parts by weight, 120 parts by weight of synthetic silica having an apparent average particle diameter of 1.4 μm, 20 parts by weight of styrene-butadiene latex, and 10 parts by weight of other auxiliaries were mixed to obtain a pseudo-adhesive pressure-sensitive adhesive composition. . This pressure-sensitive adhesive composition was applied onto the above-described base sheet at a concentration of 7 g / m ² by an air knife coater of a contour coating method to obtain a pseudo-adherable recording paper. Next, the constant A, which is an index of the heat radiation property of the recording paper, was measured by the method described above. Also,
After leaving this recording paper in an environment of 23 ° C. and 50% RH for 24 hours or more, the recording surfaces are pressed together at a linear pressure of 49 kN / m and a speed of 10 m / min using a roller-type press. After 2 hours, a tensile speed of 30
A T-type peel test was performed under the condition of 0 m / min to measure the adhesive strength. Embodiment 2 FIG. 0.68 g of base sheet density
/ Cm ³ , and a pseudo-adhesive recording paper was obtained in the same manner as in Example 1 except that the application method of the pressure-sensitive adhesive composition was a non-contour coating type rod coater. . The same test as in Example 1 was performed. Comparative Example 1 0.75 g of base sheet density
/ Cm ³ , and a pseudo-adhesive recording paper was obtained in the same manner as in Example 1 except that the application method of the pressure-sensitive adhesive composition was a non-contour coating type rod coater. . The same test as in Example 1 was performed. Table 1 shows the test results of the pseudo adhesive sheets produced in the examples and comparative examples. The adhesive strength is 10 to 10
0 N / m is a preferable range for the pseudo adhesive paper. [Table 1] As is clear from the results in Table 1, it was demonstrated that the pseudo-adhesive recording paper obtained by the present invention not only has good heat radiation properties but also does not cause toner blocking during NIP processing. Was.

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Yuji Ozawa             5-21-1 Oji, Kita-ku, Tokyo Nippon Paper Industries             Inside the company product research institute (72) Inventor Yoshihiro Kuroyama             5-21-1 Oji, Kita-ku, Tokyo Nippon Paper Industries             Inside the company product research institute F term (reference) 4L055 AG18 AG47 AG52 AG63 AG71                       AG76 AG89 AG92 AH02 AH37                       AH50 AJ04 BE08 EA08 EA40                       FA15 FA30 GA10 GA50

Claims (1)

Claims 1. A recording sheet having a pressure-sensitive adhesive layer provided on at least one surface of a substrate sheet, wherein the density of the substrate sheet is 0.7 g / cm ³ or less and heating is performed. When the recording paper is passed at a speed of 5 m / min between a pair of pressurizable rolls composed of a possible inelastic roll and an elastic roll at 180 ° C. under a heating and pressurizing condition of ² kg / cm ^2. Is measured using a non-contact infrared surface temperature measuring device, and the constant A obtained by approximating the following equation (1) is 1.20 or more. A pseudo-adhesive recording paper characterized by the following. ^{_{T = T a + (T 0}} -T a) e -At (1) A = Constant T = surface temperature (℃) _{T a} = ambient temperature (23 ℃) _{T 0} = roll immediately after passing Temperature (° C.) t = Elapsed time (seconds) e = base of natural logarithm