JP2008031600A - Heat-resistant spun bond and cleaning sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat-resistant filament nonwoven fabric excellent in thermal shrinkage, strength, chemical resistance, acid resistance, lint free property and recyclability, and to provide a cleaning roll using the nonwoven fabric and used for copying machines. <P>SOLUTION: This heat-resistant filament nonwoven fabric has a melting point of ≥260°C, a longitudinal strength of ≥50 N/5cm, and a dry heat shrinkage rate of ≤1.5%, when thermally treated at 200°C for one hour. The heat-resistant filament nonwoven fabric uses a heat-resistant thermoplastic resin being polyphenylene sulfide. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a heat-resistant long fiber nonwoven fabric having heat resistance, high strength, and excellent chemical resistance and acid resistance. In addition, if the heat-resistant long fiber nonwoven fabric is used in a cleaning roll of a copying machine or a printer, it will not change even if it is used for a long period of time at high temperatures, and since it is a long fiber, it will not fall off and is used because it is 100% heat-resistant fiber. The present invention relates to a cleaning sheet that can be recycled later.

At present, in an electrophotographic apparatus such as a copying machine, a laser beam printer, and a facsimile, a copy sheet such as paper or film carrying an unfixed toner image is supplied between a fixing roll and a pressure roll, and heated and heated. A means for fixing toner on the surface of a copy sheet by pressure is generally used. In an electrophotographic apparatus having such a structure, a cleaning sheet that removes unnecessary toner adhering to a roller is required. Therefore, many studies on a cleaning sheet suitable for an electrophotographic apparatus have been made. A nonwoven fabric manufactured by heating and pressurizing a fiber web containing polyamide fibers and unstretched polyester fibers with a heat calender roll is disclosed (for example, see Patent Document 1). However, when used as a heating roll in an electrophotographic apparatus, there is a problem that the polyester fibers are melted and the toner removal performance is lowered. In order to solve this problem, a sheet made of a heat-resistant fiber such as para-aramid fiber and a thermoplastic resin having a melting point of 200 ° C. or higher is disclosed. With such a configuration, it is considered that the temperature dependency of the toner removal performance is reduced. However, even such a sheet cannot satisfy a demand that has been strongly demanded especially in electrophotographic apparatuses in recent years. In other words, as the speed of electrophotographic devices has rapidly increased in recent years, the friction between the sheet and the roller increases, and fiber scraps or melted thermoplastic adhesive fibers adhere to the roller, resulting in poor printing. It has a problem.
Further, since the conventional cleaning sheet uses adhesive fibers or the like, it is difficult to separate used sheets, and there is no choice but to dispose of them by incineration.
JP-A-6-3999 JP 2005-266470 A

  The present invention has been made in the background of the above-described prior art, and it is an object of the present invention to prevent melt film formation with a heating roll, less fiber dropping, and to enable recycling of a cleaning roll after use. is there.

  As a result of intensive studies to solve the above problems, the present inventors have finally completed the present invention. That is, the present invention is (1) a heat-resistant long fiber nonwoven fabric characterized by having a melting point of 260 ° C. or higher, a longitudinal strength of 50 N / 5 cm or higher, and a dry heat shrinkage of 1.5% or less when heat-treated at 200 ° C. for 1 hour; 2) The heat-resistant thermoplastic resin used is polyphenylene sulfide, the heat-resistant long-fiber nonwoven fabric according to (1), and the heat-resistant long-fiber nonwoven fabric according to (3) (1) or (2), Cleaning sheet for a copier.

  Since the heat-resistant nonwoven fabric of the present invention has less fiber waste and does not contain components that melt even at high temperatures, when used as a copying machine cleaning sheet, it is possible to sufficiently cope with high-speed copying machines. Since the cleaning sheet can be made of only the heat-resistant component, there is an advantage that it can be recycled.

The present invention will be described in detail below.
The heat resistant long fiber nonwoven fabric of the present invention preferably has a melting point of 260 ° C. or higher. If the long-fiber nonwoven fabric has a melting point of 260 ° C. or higher, the occurrence of foreign matter such as fiber scraps and melt-degraded materials is extremely low even in harsh use environments that receive high friction at high temperatures, such as copy machines, preventing machine failures, This is because the nonwoven fabric is extremely useful for reducing printing defects and extending the part replacement cycle. Moreover, since a nonwoven fabric can be comprised only with one heat resistant material, it has the advantage that it becomes a uniform nonwoven fabric without other components unevenly distributed, and performance, such as a cleaning characteristic, is stabilized.
The “melting point” in the present invention refers to a temperature obtained from a differential thermal analysis curve (DTA curve) obtained by differential thermal analysis specified in JIS K7121.

The heat-resistant long fiber nonwoven fabric of the present invention preferably has a longitudinal strength of 50 N / 5 cm or more. This is because if it has such strength, it can be used stably even when subjected to severe friction when it is made into a tape.

The heat-resistant long fiber nonwoven fabric of the present invention preferably has a dry heat shrinkage of 1.5% or less when heat-treated at 200 ° C. for 1 hour. This is because if the dry heat shrinkage is 1.5% or less, wrinkles are small even in an environment used at high temperatures, and high cleaning properties can be stably obtained when used as a cleaning sheet. A more preferable dry heat shrinkage rate is 1.3% or less, and even more preferably 1.1% or less.

Examples of the material used for the heat-resistant long fiber nonwoven fabric of the present invention include polytetrafluoroethylene and polyphenylene sulfide (hereinafter referred to as PPS). PPS is recyclable and generates harmful gases even if it is finally incinerated. Is particularly preferable.

This is because the nonwoven fabric, which is the cleaning sheet of the present invention, is a long-fiber nonwoven fabric, so that there is little generation of fiber waste due to friction during cleaning, and since it is not unevenly distributed, it has excellent wiping properties for toner and the like. Such a state is difficult in a short fiber nonwoven fabric. In other words, fiber scraps adhere to the surface of the hot roll due to the fiber dropping of the short fibers, and the cleaning property is deteriorated.

The basis weight and thickness of the nonwoven fabric (cleaning sheet) of the present invention are not particularly limited, but the basis weight is preferably 20 to 60 g / m 2 and the thickness is preferably 0.02 to 0.20 mm, more preferably 0. 0.02 to 0.15 mm. If it is 0.02 mm or less, excessive thermocompression bonding or a low basis weight will occur, and it will be difficult to develop the desired tensile strength described below. In addition, when the thickness is 0.20 mm or less, for example, when a cleaning sheet or the like is wound around a roll shape in a certain amount, the winding length can be increased and the replacement cycle can be extended.

The heat-resistant long fiber nonwoven fabric of the present invention may be used as a copying machine cleaning sheet. Since the heat-resistant long fiber nonwoven fabric of the present invention is excellent in heat resistance, abrasion resistance and wiping property, when used as a cleaning sheet for a copying machine fixing member, the generation of foreign matters is dramatically reduced, and the cleaning performance and printing defects are reduced. This is because it can be reduced. More specifically, examples include a fixing roll in an electrophotographic apparatus such as a copying machine, a laser beam printer, or a facsimile machine. In addition to the fixing roll, the toner is directly fixed on the copy sheet in place of the fixing roll. Examples thereof include a circulation belt, a fixing roll, or a transfer roll provided in contact with the circulation belt to which toner is transferred.

  The cleaning sheet of the present invention can wipe off the toner and the like by pressing against the fixing member, but may contain oil in order to improve the wiping property of the toner and the like. Examples of the oil include methyl silicone oil, dimethyl silicone oil, ethyl silicone oil, phenyl silicone oil, amino modified silicone oil, epoxy modified silicone oil, mercapto modified silicone oil, 3,3,3-trifluoropropyl silicone oil, and the like. These silicone oils can be included alone or in admixture. In addition, although the adhesion amount of oil changes with thickness of a cleaning sheet, etc., it is preferable that it is 100 g / m <2> or less. Further, the viscosity of the oil is preferably 10 to 30,000 centistokes so that the oil diffusibility on the surface of the fixing member is excellent.

The fineness of the heat-resistant long fiber of the present invention is not particularly limited, but is preferably 3.3 dtex or less. This is because heat-resistant long fibers disappear as described later and aggregate and solidify at the intersections of fibers, but if the thermoplastic resin fibers are thin, the thermoplastic resin fibers are no longer in fiber form, and the fiber dispersion is reduced. It is possible to produce a non-woven fabric (cleaning sheet) excellent in wiping property that can use the wiping property by individual heat-resistant fibers, in which the thermoplastic resin coagulates uniformly throughout the non-woven fabric (cleaning sheet) without losing uniformity. is there. A more preferable fineness is 2.2 dtex or less, and a still more preferable fineness is 1.6 dtex or less. Although the minimum of the fineness of a thermoplastic resin fiber is not specifically limited, It is preferable that it is 0.01 dtex or more.

When a PPS resin is used as the long-fiber nonwoven fabric of the present invention, it is preferable to carry out a crystallization step of crystallizing the heat-resistant thermoplastic resin by heat-treating the sheet spun by the spunbond method. It is because high sheet strength and excellent heat shrinkage characteristics can be obtained by performing the crystallization process by heat treatment.

The heat treatment temperature for crystallizing the PPS sheet is preferably 160 to 250 ° C, more preferably 180 to 220 ° C. In the case of PPS, crystallization tends to be insufficient at a temperature lower than 160 ° C., and when it exceeds 250 ° C., it approaches the extrapolated dissolution start temperature (the temperature at which the resin starts to melt), and the PPS form begins to change. The state of the PPS in the (cleaning sheet) changes. The heat treatment in this crystallization step is preferably carried out under no pressure in any stage so that the thermoplastic resin does not form a linear or curved continuous film.
Moreover, you may hold | maintain the shape by a tenter at the time of heat processing.

In this way, the nonwoven fabric (cleaning sheet) of the present invention can be produced, but there may be variations in thickness. Also, the tensile strength may not be within the desired range. In such a case, it is preferable to perform the calendar process (calendar process) at a temperature lower than the softening temperature of the thermoplastic resin fibers (preferably a temperature lower by 20 ° C. or more) to solve the above problems. The pressure in the calendar process is not particularly limited because it varies depending on the degree of thickness variation, desired apparent density, desired tensile strength, desired tear strength, and the like. This pressure can be appropriately set by repeating the experiment.
In addition, the cleaning sheet containing oil can be manufactured by immersing the nonwoven fabric manufactured by the above-mentioned method in oil, or spraying or coating the nonwoven fabric with oil.
The cleaning roll for copying used by the product of the present invention can be used for a molded product by separating the silicone oil after use and re-pelletizing the PPS resin.

The present invention will be specifically described below with reference to examples. However, the present invention is not limited thereby. The evaluation and characteristic values of the following examples and the like were based on the following measuring methods.

・ Weight per unit (g / m2)
Sample size 5 cm wide × 20 cm Average value of 5 points in the vertical direction and 5 points in the horizontal direction, a total of 10 points.

(2) Thickness (mm)
Measure with a thickness gauge (load 20 g / cm 2 area 4 cm 2) every 20 cm in the width direction. Average value of the number of 10 points in the width direction.

・ Tensile strength (N / 5cm)
According to JISL1906, evaluation was performed using a Tensilon machine at a distance between chucks of 10 cm and a head speed of 20 cm / min.

(4) Thermal contraction rate (%)
In accordance with JISL1906, the shrinkage after heat treatment at 200 ° C. for 1 hour is calculated.

(5) Melting point (° C)
It is obtained from a differential thermal analysis curve obtained by differential thermal analysis according to JISK7121.

(6) Evaluation of wiping property A color copying machine (Ricoh's imageio Neo 352) was prepared, and the entire black image was copied 20 times with the cleaning device of the color copying machine removed. Next, a cleaning device (a sandwich width between a cylindrical rod-shaped body made of foamed silicone rubber and a fixing roll: 3 mm) provided with a cleaning sheet supply body wound around a shaft from one end of the cleaning sheet of the example is used as the above-described monochrome. Installed in a copier. Thereafter, three copies of the whole white image were continuously made, and the stain on the surface of the third copy paper was observed by toner.
Observation result ○: No contamination by toner, good Δ: Some contamination by toner is seen.
X: Many stains due to toner are observed.

(Example 1)
A PPS resin having an MFR of 122 g / min. Was spun at a spinning temperature of 300 ° C. from a nozzle with an orifice diameter of 0.23 mm at a single hole discharge rate of 1.2 g / min. Taking up while cooling at 3 m / sec, picking up with an ejector installed at a point 800 mm below the nozzle while sucking at a yarn speed of 3800 m / min, and taking up moving at a speed of 50 m / min at a point 1500 mm below the nozzle The fiber bundle was spun off and laminated on the net surface. The nonwoven fabric laminated on the net surface was processed with a calendar roller at 90 ° C. and a linear pressure of 6 kg / cm to obtain a long fiber nonwoven fabric. The melting point of the obtained long fiber nonwoven fabric was 285 ° C.
After processing the obtained base material at 200 ° C. with a tenter heat treatment machine, a heat-resistant long-fiber non-woven fabric subjected to partial thermocompression bonding with an embossing roll having an area ratio of 22% at a temperature of 250 ° C. and a linear pressure of 40 kg / cm was obtained.

(Example 2)
After heat treatment, a heat-resistant long fiber nonwoven fabric was obtained in the same manner as in Example 1 except that it was thermocompression bonded with a calender roll having an area ratio of 100% at a temperature of 250 ° C. and a linear pressure of 80 kg / cm.

(Comparative Example 1)
In addition to spinning a PET resin having an intrinsic viscosity of 0.63 at a spinning temperature of 280 ° C., the long-fiber nonwoven fabric obtained in the same manner as in Example 1 had a melting point of 258 ° C.

(Comparative Example 2)
After heat treatment, a heat resistant long fiber nonwoven fabric was obtained in the same manner as in Example 1 except that the embossing roll was not used.

(Comparative Example 3)
Heat-resistant fiber having fibrils made of para-type wholly aromatic polyamide (product name: Twaron 1094, manufactured by Teijin, carbonization temperature: 500 ° C. or more), and polyester fiber having a fineness of 0.11 dtex and a fiber length of 3 mm made of polyethylene terephthalate ( Melting point: 260 ° C.).
Next, a slurry was formed in which the heat-resistant fiber in which fibrillation was promoted by a refiner and the polyester fiber were dispersed at a mass ratio of 70:30. Thereafter, the slurry is supplied to each net to a paper machine equipped with a forward flow net, an inclined wire type short net, a forward flow net, and a Yankee dryer, and each wet fiber web is formed, and each wet fiber web is laminated. The laminated wet fiber web was formed, and then the laminated wet fiber web was dried by a Yankee dryer set at a temperature of 120 ° C. to form a three-layer wet fiber web in which the fiber orientation was unidirectional, random, and unidirectional. .
Next, a far-infrared ceramic heater (manufactured by Ryoka) set at a temperature of 490 ° C. and a distance of 15 m / min. The polyester fiber was melted by passing through the three-layer wet fiber web to eliminate the fiber form, and the melted polyester resin was aggregated at the intersection of the heat-resistant fibers. Note that the three-layer wet fiber web was passed through the far-infrared ceramic heater with a distance of 110 mm. Further, hot air having a temperature of 150 ° C. was blown onto the moving three-layer wet fiber web.
Subsequently, it was air-cooled at room temperature under no pressure to coagulate the agglomerated polyester resin to produce a coagulated nonwoven fabric.
Thereafter, the coagulated nonwoven fabric was passed through a dryer heated to a temperature of 220 ° C. for 5 seconds to crystallize the polyester resin, thereby producing a crystallized nonwoven fabric, that is, a cleaning sheet.
Hereinafter, the characteristic table in Examples 1-2 and Comparative Examples 1-3 is described.

  According to the present invention, it is possible to supply a heat-resistant long fiber nonwoven fabric excellent in heat shrinkability, high in strength, excellent in lint-free properties, and excellent in recyclability as compared with conventional heat-resistant short fiber nonwoven fabrics. Recycled heat-resistant resin is used for molded products and can greatly contribute to the industry. Also, zero emission in the copy cleaning roll can be realized by reusing the PPS resin by recycling.

Claims (3)

A heat-resistant long fiber nonwoven fabric having a melting point of 260 ° C. or higher, a longitudinal strength of 50 N / 5 cm or higher, and a dry heat shrinkage of 1.5% or less when heat-treated at 200 ° C. for 1 hour. The heat-resistant long-fiber nonwoven fabric according to claim 1, wherein the heat-resistant thermoplastic resin used is polyphenylene sulfide. A cleaning sheet for a copying machine, comprising the heat-resistant long fiber nonwoven fabric according to claim 1.