JP6414973B2 - Manufacturing method of paper feed roller - Google Patents

Description

The present invention relates to a manufacturing method of the paper feed rows La suitably used as a pinch roller, etc. In for example, an image forming apparatus.

In an image forming apparatus such as an electrostatic copying machine, a pinch roller used for transporting paper with a pair of rollers made of rubber or the like is formed of a material having a smaller friction coefficient than rubber, such as resin. It is common.
In particular, when the pinch rollers are not arranged in parallel to the paired rollers but at a slight angle so as to bring the sandwiched paper to one side in the width direction, the pinch roller will move on the paper after the paper has been brought in one direction. Therefore, the friction coefficient is particularly required to be small.

However, since a pinch roller made of resin or the like is harder than rubber, for example, when it comes into direct contact with a soft rubber counter roller between paper feeds, the counter roller may be damaged.
Patent Document 1 describes that a paper feed roller such as a pinch roller is formed integrally with a shaft by injection molding a resin composition in which resin beads are blended with a urethane-based thermoplastic elastomer.

  According to this configuration, the urethane-based thermoplastic elastomer that is softer than the resin and has a smaller friction coefficient than the rubber is further blended with the resin beads that function to further reduce the friction coefficient. While maintaining the softness of the feed roller moderately, the friction coefficient of the paper feed roller can be reduced to a certain extent.

JP 2013-35613 A

However, the above effects are limited. That is, in the configuration of Patent Document 1, as is clear from the results of Examples and Comparative Examples, the degree of reduction in the friction coefficient due to the increase in the blending ratio of the resin beads is insufficient.
In particular, in order to set the friction coefficient of the paper feed roller to be less than 0.5 so as to be used as a pinch roller for the above-mentioned shifting, the range of the embodiment of Patent Document 1 (the range specified in Paragraph [0030]). A large amount of resin beads must be blended, and the paper feed roller is hardened to the same extent as that made of resin. There is a problem that the counter roller is likely to be damaged when directly contacted.

The inventor believes that the formation of the paper feed roller by injection molding of the resin composition is the cause of the above problems.
In other words, in the injection molding, the surface shape of the outer peripheral surface of the paper feed roller that is in contact with the paper is a smooth surface with a high coefficient of friction defined by the mold surface, and most of the resin beads are surfaces of the outer peripheral surface. Since it will be in a state where it is buried inside and hardly contributes to the reduction of the friction coefficient, as described above, there is a tendency that the degree of reduction of the friction coefficient due to the increase in the blending ratio of the resin beads becomes insufficient.

Moreover, since the injection molding method is adopted in Patent Document 1 as described above, paper feeding is coupled with the need for an expensive injection mold and the low batch productivity of the molding process. There is also a problem that the manufacturing cost of the roller is high.
An object of the present invention is made by blending a spherical filler such as resin beads to the thermoplastic elastomer, yet flexible, yet low coefficient of friction paper feed roller than the current method of cost inexpensively be paper feed row La Is to provide.

The present invention is compatible with the cross-sectional shape of a paper feed roller in which a resin composition containing a thermoplastic elastomer and a spherical filler is maintained at a temperature lower than T ₁ -5 ° C. with respect to the melting point T ₁ (° C.) of the thermoplastic elastomer. This is a paper feed roller manufacturing method for manufacturing a paper feed roller having a coefficient of friction of less than 0.5 and a type A durometer hardness of 90 or less through a process of extrusion through a die.

According to the present invention, by blending a spherical filler such as resin beads to the thermoplastic elastomer, yet flexible, yet low coefficient of friction paper feed roller than the current method of cost inexpensively be paper feed row La Can provide.

It is a figure explaining the method to measure the friction coefficient of the paper feed roller manufactured by the manufacturing method of this invention. It is a graph which shows the relationship between the friction coefficient and the type A durometer hardness in the Example of this invention, a comparative example, and the Example of patent document 1, and a comparative example.

< Method for manufacturing paper feed roller>
According to the production method of the present invention , the paper feed roller extrudes the resin composition containing the thermoplastic elastomer and the spherical filler as described above into the atmosphere or the like through a die corresponding to the cross-sectional shape of the paper feed roller. Formed.
Therefore, for example, by appropriately setting the conditions for extrusion molding, the outer peripheral surface can be a surface having a smaller friction coefficient than the smooth outer peripheral surface formed by injection molding.

Moreover, most of the spherical fillers present in the vicinity of the outer peripheral surface protrude from the smooth surface depending on the resin pressure during extrusion molding and affinity with thermoplastic elastomer, etc., and contribute to further reduction of the friction coefficient. To do.
Therefore, according to the present invention, the friction coefficient of the paper feed roller can be more efficiently reduced by increasing the degree of reduction of the friction coefficient due to the increase in the blending ratio of the spherical filler. In the following, it is possible to make the paper feed roller have good flexibility and to make its coefficient of friction smaller than the current state.

That is, by setting the coefficient of friction to less than 0.5, and preferably 0.46 or less, after the paper feed roller is used as a pinch roller, for example, and the paper is moved in one direction, the paper is idled satisfactorily on the paper. Wrinkles and the like can be prevented even better.
Further, by setting the type A durometer hardness to 90 or less, it is possible to further prevent the counter roller from being damaged when the paper feed roller as a pinch roller is brought into direct contact with the rubber counter roller.

Moreover, according to the present invention, the paper feeding roller can be manufactured at a lower cost by extrusion molding that does not require an expensive metal mold and can be continuously molded.
Note that the paper feed roller preferably has a certain level of frictional force in consideration of functioning well in order to move the paper in one direction, for example, as a pinch roller. It is preferably 2 or more.

In addition, for example, if a plasticizer is added to a thermoplastic elastomer, the paper feed roller can be made softer than the thermoplastic elastomer itself. However, considering the wear resistance and strength of the paper feed roller, its type A durometer Even in the above range, the hardness is preferably set to be equal to or higher than the type A durometer hardness of the thermoplastic elastomer itself.
In the present invention, the friction coefficient and type A durometer hardness of the paper feed roller are represented by values measured by the following methods.

<Coefficient of friction>
As shown in FIG. 1, a plate 1 made of polytetrafluoroethylene (PTFE) is horizontally installed, and one end is connected to the load cell 3 between the plate 1 and a paper feed roller 2 for measuring a friction coefficient. With the other end of the × 4 mm size paper 4 (P paper (plain paper) manufactured by Fuji Xerox Co., Ltd.) sandwiched between the other ends of the paper 5 on the shaft 5 of the paper feed roller 2 as indicated by the solid arrow in the figure. A vertical load W of 98 N (= 100 gf) is applied.

In this state, under the environment of a temperature of 23 ± 2 ° C. and a relative humidity of 55 ± 10%, the conveyance force F applied to the load cell 3 by rotating the paper feed roller 2 at a peripheral speed of 30 mm / second in the direction indicated by the dashed line arrow R. (Gf) is measured.
From the measured conveying force F and vertical load W (= 100 gf), the formula (1):

Friction coefficient = F (gf) / W (gf) (1)
Obtain the coefficient of friction.
<Type A durometer hardness>
The resin composition that becomes the basis of the paper feed roller is formed into a sheet shape having a thickness of 2 mm, and three sheets thereof are stacked to form a test piece.

And using this test piece, in an environment of a temperature of 23 ± 2 ° C., Japanese Industrial Standard JIS K6253-3-3 _{: 2012} “Vulcanized rubber and thermoplastic rubber—How to obtain hardness—Part 3: Durometer hardness” The numerical value after 15 seconds is read in accordance with the measurement method described above to obtain the type A durometer hardness.
<Thermoplastic elastomer>
As the thermoplastic elastomer, various thermoplastic elastomers that are softer than the resin and smaller in friction coefficient than the rubber can be used as described above. Examples of such thermoplastic elastomers include polyester-based thermoplastic elastomers, urethane-based thermoplastic elastomers, styrene-based thermoplastic elastomers, and olefin-based thermoplastic elastomers.

As the counter roller combined with the pinch roller, for example, an ethylene propylene diene rubber (EPDM) roller is often used, and the EPDM roller is generally mixed with a plasticizer such as paraffin oil. It is.
However, when the plasticizer moves from the counter roller to the pinch roller, the pinch roller may become too soft and easily wear.

For this reason, the paper feed roller used as a pinch roller combined with an EPDM counter roller is preferably formed of a polyester thermoplastic elastomer or a urethane thermoplastic elastomer to which the plasticizer is difficult to migrate.
In consideration of further reducing the friction coefficient of the paper feed roller, the paper feed roller is more preferably formed of a polyester-based thermoplastic elastomer among the above two types.

Specific examples of the polyester-based thermoplastic elastomer include, for example, one or more of the types of polyester-based thermoplastic elastomers of the Hytrel (registered trademark) manufactured by Toray DuPont Co., Ltd. that can be extruded. It is done.
<Spherical filler>
The spherical filler used in the present invention is not limited to a true spherical shape, and may include a so-called bead shape or granular shape.

  As the spherical filler, any of various organic or inorganic spherical fillers that are not melted or deformed by heat at the time of extrusion molding and can reduce the friction coefficient of the paper feed roller can be used. Examples of the spherical filler include one or more of resin beads made of a hard resin such as a cross-linked acrylic resin and silicone resin, glass beads, spherical silica, and spherical alumina.

Moreover, as a spherical filler, in order to improve affinity, compatibility, etc. with a thermoplastic elastomer, what processed the surface with the coupling agent etc. may be used, for example.
Considering not only the hardness and strength but also the affinity and compatibility with the above thermoplastic elastomer, the ease of handling and the availability, etc., crosslinked acrylic resin beads or glass beads are preferred as the spherical filler.

In consideration of further improving the effect of reducing the coefficient of friction by projecting to the outer peripheral surface of the paper feed roller as described above, the average particle size of the spherical filler is 1 μm or more, especially 5 μm or more, especially 15 μm. The above is preferable.
However, since the spherical filler having a too large particle size is likely to fall off from the outer peripheral surface of the paper feed roller during use, the average particle size of the spherical filler is preferably 120 μm or less, particularly preferably 100 μm or less even in the above range. .

Specific examples of the crosslinked acrylic resin beads include, for example, Metabrene (registered trademark) F-410 (average particle size: 100 μm ) manufactured by Mitsubishi Rayon Co., Ltd., and Ganzpearl (registered trademark) GBX- manufactured by Aika Industry Co., Ltd. Examples thereof include at least one of 10S [average particle diameter: 8 to 12 μm ].
As the glass beads , beads made of various glasses such as soda lime glass and low alkali glass can be used. Specific examples of the glass beads include, for example, general purpose glass beads GB301S [soda lime glass, average particle size: 50 μm ], EGB731 [low alkali glass, average particle size: 20 μm ], EGB731C manufactured by Potters Barotini Co., Ltd. One type or two or more types such as [low alkali glass, average particle size: 20 μm , acrylsilane treatment] can be used.

The blending ratio of the spherical filler can be appropriately set according to the type and average particle size of the spherical filler, the type and grade of the thermoplastic elastomer to be combined, the hardness, and the target hardness and friction coefficient of the paper feed roller.
For example, it is blended in a polyester-based thermoplastic elastomer having a type A durometer hardness of 80 in a state where no spherical filler is blended, and the paper feed roller has a type A durometer hardness of 90 or less and a friction coefficient of less than 0.5. For this purpose, the blending ratio of the crosslinked acrylic resin beads is preferably 10 parts by mass or more, particularly preferably 15 parts by mass or more, and preferably 30 parts by mass or less, per 100 parts by mass of the polyester-based thermoplastic elastomer.

Further, the mixing ratio of the glass beads under the same conditions is preferably 15 parts by mass or more, particularly preferably 20 parts by mass or more, and 100 parts by mass or less, particularly 80 parts by mass or less, per 100 parts by mass of the polyester-based thermoplastic elastomer. Is preferred.
<Other ingredients>
You may mix | blend various additives with a resin composition at arbitrary ratios as needed.

Examples of the additives include organic or inorganic fillers, colorants such as pigments, processing aids such as plasticizers, conductivity-imparting agents, and various stabilizers.
< Manufacturing method >
According to the production method of the present invention, the resin composition containing each of the above components has a cross-sectional shape of a paper feed roller in which the temperature is set to less than T ₁ −5 ° C. with respect to the melting point T ₁ (° C.) of the thermoplastic elastomer. through a process of extruding through the corresponding die, the paper feed roller Ru produced.

The reason why the temperature of the die is limited to the above range is as follows.
That is, when the resin composition is extruded through a die set to a temperature higher than the above range, the resin composition is smoothly extruded from the die while maintaining a good molten state.
For this reason, the outer peripheral surface of the extruded paper feed roller becomes smooth and many spherical fillers are buried in the outer peripheral surface. As a result, the friction coefficient cannot satisfy the above-mentioned range of less than 0.5.

  On the other hand, when the die temperature is set within the above range and the resin composition is extruded while the temperature is lowered, the resin composition is not smoothly extruded as in the previous case, and the extruded paper The feed roller has a moderately rough outer peripheral surface, and its smoothness is moderately lowered, and many spherical fillers protrude from the outer peripheral surface. As a result, the friction coefficient of the manufactured paper feed roller is less than 0.5. It becomes.

In consideration of making the friction coefficient of the paper feed roller as small as possible by the above mechanism, it is preferable to set the die temperature as low as possible even in the above range, and in particular, to the melting point T ₁ (° C.) of the thermoplastic elastomer. On the other hand, it is preferably set to T ₁ −10 ° C. or lower, particularly T ₁ −15 ° C. or lower, particularly T ₁ −20 ° C. or lower.
However, if the temperature of the die is too low, the outer peripheral surface may be too rough and the appearance of the paper feed roller may be deteriorated, or the extrusion may not be smoothly performed. Therefore, the die temperature is preferably set to T ₁ -50 ° C. or higher with respect to the melting point T ₁ (° C.) of the thermoplastic elastomer even in the above range.

In the present invention, the paper feed roller can be manufactured in the same manner as usual except that the die temperature is set within the above range.
That is, a spherical filler or the like is dry blended into a thermoplastic elastomer at a predetermined ratio, kneaded and pelletized, and then extruded through a die set at the above temperature while being kneaded in an extruder cylinder and cooled. After that , the paper feed roller is manufactured by cutting to a predetermined length.

  In order to smoothly reduce the temperature of the resin composition in accordance with the temperature of the die, the temperature of the head to which the die is connected or the adapter to which the head is connected to the cylinder of the extruder is adjusted to the temperature of the die. You may adjust suitably.

<Example 1>
Polyester thermoplastic elastomer [Hytrel 3078 manufactured by Toray DuPont Co., Ltd., melting point T ₁ : 170 ° C.] 100 parts by mass, crosslinked acrylic resin beads [Metbrene F-410 manufactured by Mitsubishi Rayon Co., Ltd., average Particle size: 100 μm ] 15 parts by mass, and 1 part by mass of titanium oxide (SA-1, manufactured by Sakai Chemical Industry Co., Ltd., anatase type) as a pigment were dry-blended, and under the temperature conditions shown in Table 1 below, 2 A resin composition pellet was prepared by extruding into a string having a diameter of about 2 mm using a shaft extruder and then cutting to a length of 2 to 4 mm.

Next, the produced pellets were supplied to a single screw extruder, and were extruded into a cylindrical shape having an inner diameter of 5 mm and an outer diameter of 7 mm through a die connected to the head under the temperature conditions shown in Table 2 below, and then cut to a length of 10 mm. Thus, a paper feed roller as a pinch roller was manufactured. Temperature of the die was T ₁ -25 ° C. relative to the melting point T ₁ of the thermoplastic elastomer _(° C.).

<Example 2>
Pellets were produced in the same manner as in Example 1 except that the blending ratio of the crosslinked acrylic resin beads was 30 parts by mass per 100 parts by mass of the polyester-based thermoplastic elastomer, and a paper feed roller was produced.
<Comparative example 1>
Pellets were produced in the same manner as in Example 1 except that the crosslinked acrylic resin beads were not blended to produce a paper feed roller.

<Comparative example 2>
Pellets were produced in the same manner as in Example 1 except that the blending ratio of the crosslinked acrylic resin beads was 5 parts by mass per 100 parts by mass of the polyester-based thermoplastic elastomer, and a paper feed roller was produced.
<Example 3>
Instead of the cross-linked acrylic resin beads, 20 parts by weight of glass beads per 100 parts by weight of the polyester-based thermoplastic elastomer [General purpose glass beads GB301S manufactured by Potters Ballotini Co., Ltd., soda-lime glass, average particle size: 50 A pellet was prepared in the same manner as in Example 1 except that [ μm ] was blended to produce a paper feed roller.

<Example 4>
Instead of cross-linked acrylic resin beads, 50 parts by weight of glass beads per 100 parts by weight of polyester-based thermoplastic elastomer [the above-mentioned general purpose glass beads EGB731C manufactured by Potters Ballotini Co., Ltd., low alkali glass, average particle size: 20 A pellet was prepared in the same manner as in Example 1 except that [ mu.m , acrylic silane treatment] was blended to produce a paper feed roller.

<Example 5>
Pellets were produced in the same manner as in Example 4 except that the mixing ratio of the general-purpose glass beads EGB731C was 80 parts by mass per 100 parts by mass of the polyester-based thermoplastic elastomer, and a paper feed roller was produced.
The friction coefficient of the paper feed roller manufactured in each of the above examples and comparative examples was measured by the method described above.

Moreover, after extruding the pellets produced in each example and comparative example into a sheet shape having a thickness of 2 mm and a width of about 40 mm under the temperature conditions shown in Table 2, three sheets of the sheets are stacked to measure type A durometer hardness. The test piece was used. And the type A durometer hardness of the produced test piece was measured by the method demonstrated previously.
Further, the above sheet is punched out to produce a dumbbell-shaped No. 3 test piece defined in Japanese Industrial Standard JIS K6251 _{: 2010} “vulcanized rubber and thermoplastic rubber—how to obtain tensile properties”. Tensile strength TS (MPa) and tensile elongation E _b (%) when a tensile test was performed in accordance with the test method described in the above standard in an environment of temperature 23 ± 2 ° C. Asked.

  The above results are shown in Tables 3 and 4.

FIG. 2 shows the relationship between the coefficient of friction and the type A hardness in each of the examples in Tables 3 and 4 together with the results of Examples and Comparative Examples in Patent Document 1.
From FIG. 2, Table 3, and Table 4, the injection molding employed in Patent Document 1 cannot form a paper feed roller having a friction coefficient of less than 0.5 and a type A durometer hardness of 90 or less. According to the present invention, it has been found that a paper feed roller that can satisfy the above-mentioned conditions can be formed by blending a spherical filler with a thermoplastic elastomer and performing extrusion molding.

<Examples 6 to 8, Comparative Examples 3 and 4>
A paper feed roller was produced in the same manner as in Example 4 except that extrusion molding was performed under the temperature conditions shown in Table 5 below.
And the friction coefficient of the paper feed roller manufactured in each of the above examples and comparative examples was measured by the method described above. The results are shown in Table 5 together with the results of Example 4.

From Table 5, by setting the temperature of the die at the time of extrusion molding to less than T ₁ −5 ° C. with respect to the melting point T ₁ (° C.) of the thermoplastic elastomer, the paper feed roller having a friction coefficient of 0.5 μm or less. It was found that can be manufactured.

1 Plate 2 Paper feed roller 3 Load cell 4 Paper 5 Shaft F Conveying force W Vertical load

Claims (3)

Thermoplastic elastomers, and the resin composition comprising a spherical filler, the thermal melting point T _{1 (°} C.) of thermoplastic elastomer and the temperature was set to less than T ₁ -5 ° C. against, corresponding to the cross-sectional shape of the paper feed roller die The paper feed roller manufacturing method of manufacturing a paper feed roller having a friction coefficient of less than 0.5 and a type A durometer hardness of 90 or less through an extrusion molding process. The method for manufacturing a paper feed roller according to claim 1, wherein the thermoplastic elastomer is a polyester-based thermoplastic elastomer . The method for manufacturing a paper feed roller according to claim 1, wherein the spherical filler is at least one selected from the group consisting of crosslinked acrylic resin beads and glass beads .

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