JP2004346137A - Elastic member and paper feed roller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an elastic member which has a high frictional coefficient, holds the high frictional coefficient, and has high durability, and to provide a paper feed roller comprising the elastic member. <P>SOLUTION: This elastic member 10 is characterized by nano-dispersing a resin 12 having higher abrasion resistance than that of a matrix 11 in the matrix 11 comprising an elastomer, using the surface exposed portions of the matrix 11 as groove-forming portions 11A, when worn out, and using the resin 12 as frictional coefficient-maintaining portions 12A left as projections T. This paper feed roller comprises the elastic member 10 and is used for an image-forming apparatus. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【００５５】
【表２】

【００５６】
表中の各配合の数値は重量部である。また、表中、ゴム１としては、１００％油展ＥＰＤＭ２００重量部（ゴム１００重量部＋オイル１００重量部）を使用した。ポリアミド系樹脂としては、油展ナイロン１１を使用した。
【００５７】
（実施例１〜実施例３）
実施例１〜３は、エラストマーからなるマトリクス中に、マトリクスよりも耐摩耗性を有する樹脂をナノ分散化し、マトリクスの表面露出部分が摩耗時に溝形成部分とされると共に樹脂は突起として残存して摩擦係数維持部分とされる構成とした。
具体的には、表１に示される様に、相容化剤と共に、マトリクスとなるエラストマーとして１００％油展ＥＰＤＭを、分散相となるポリアミド系熱可塑性樹脂としてポリアミド系熱可塑性樹脂である油展ナイロン１１を、上記体積比で使用した。
【００５８】
また、ポリアミド系熱可塑性樹脂の粒径の分布を以下に示す。いずれもリアクティブブレンドにより作製した。
実施例１は、小ドメイン（１０〜１００ｎｍ）：大ドメイン（１００〜１０００ｎｍ）＝４０：６０とした。
実施例２は、小ドメイン（１０〜１００ｎｍ）：大ドメイン（１００〜１０００ｎｍ）＝５０：５０とした。
実施例３は、小ドメイン（１０〜１００ｎｍ）：大ドメイン（１００〜１０００ｎｍ）＝６０：４０とした。
【００５９】
（比較例１）
比較例１は、ポリアミド系熱可塑性樹脂を使用せず、実施例と同じ１００％油展ＥＰＤＭゴムのマトリクスのみとした。
（比較例２）
比較例２は、相容化剤を用いず、ポリアミド系熱可塑性樹脂を平均粒径１μｍ以上で分散させ、リアクティブブレンドしなかった。即ち、樹脂をナノ分散化しなかった。
【００６０】
実施例１〜３、比較例１，２の紙送りローラについて後述する方法により、ポリアミド系熱可塑性樹脂の粒子径、初期摩擦係数、３万枚通紙後の摩擦係数及び摩耗量、硬度及び圧縮永久歪みについての評価・測定を行った。結果は表１、２中に記載した。
【００６１】
（ポリアミド系熱可塑性樹脂の粒子径）
走査型プローブ顕微鏡ＳＰＭ（Ｓｃａｎｎｉｎｇ Ｐｒｏｂｅ Ｍｉｃｒｏｓｃｏｐｅ）を用いて、実施例１〜３、比較例２の紙送りローラを観察し、材料のモルフォロジー及びポリアミド系熱可塑性樹脂の粒子径について評価した。また、実施例３について、０枚、１００００枚、２００００枚、３００００枚通紙後のローラの外周面の断面も観察した。実施例３の通紙枚数毎の摩耗面の断面写真を図３に示す。一辺の長さは５μｍである。実施例１〜３、比較例２の紙送りローラに用いたエラストマー材料のモルフォロジーを図４に示す。
【００６２】
（通紙後のローラ外周面の観察）
実施例３、比較例１について、２００００枚通紙後のローラの外周面を、走査型電子顕微鏡ＳＥＭ（Ｓｃａｎｎｉｎｇ Ｅｌｅｃｔｒｏｎ Ｍｉｃｒｏｓｃｏｐｅ）で観察した。観察写真を図５に示す。
【００６３】
（摩擦係数及び摩耗量の評価）
摩擦係数を図６に示す以下の方法で測定した。すなわち、紙送りローラ２１とプレート（分離シート）２３との間に、ロードセル２５に接続したＡ４サイズのＰＰＣ用紙（富士ゼロックスオフィスサプライ（株）製）２４をはさみ、図６中、黒矢印で示すように、紙送りローラ２１の回転軸２２に荷重Ｗ（Ｗ＝２５０ｇｆ）を加え、紙送りローラ２１をプレート２３に圧接させた。次いで、温度２２℃、湿度５５％の条件下で、上記紙送りローラ２１を図６中、実線の矢印ａで示す方向に、周速３００ｍｍ／秒で回転させ、通紙の前後において、図６中、白矢印で示す方向に発生した力Ｆ（ｇｆ）をロードセル２５によって測定した。そして、この測定値Ｆ（ｇｆ）と荷重Ｗ（２５０ｇｆ）とから、下記の式より摩擦係数μを求めた。この摩擦係数の測定は、通紙開始（初期摩擦係数）と３００００枚通紙終了後のそれぞれで行った。
また、３００００枚通紙終了前後の各紙送りローラの重量を測定することにより、摩耗量（ｍｇ）を求めた。
上記測定による３００００枚通紙後の摩擦係数の値は、１．７以上が優れており、１．５以上が適であり、１．５未満は不適である。
【００６４】
（数式１）
μ＝Ｆ（ｇｆ）／Ｗ（ｇｆ）
【００６５】
（硬度の測定）
上記紙送りローラの硬度をＪＩＳ６２５３のＡ型硬度計で測定した。
【００６６】
（圧縮永久歪みの測定）
紙送りローラの圧縮永久歪みをＪＩＳ−Ｋ６３０１の記載に従って測定した。数値単位は％とした。なお、圧縮永久歪みは０〜３０であるのが好ましい。
【００６７】
図３に示すように、実施例３は、通紙１００００枚、２００００枚、３００００枚の拡大写真において、いずれも摩耗面３０には、摩耗により局在化されたポリアミド系熱可塑性樹脂からなる微小な突起３２が残存し摩擦係数維持部分として点在していた。よって、紙との接触によりローラの外周面が摩耗し、通紙により、摩耗面３０であるローラの外周面に摩擦係数維持部分として突起３２が形成されていることが確認できた。
なお、図３及び図４中、橙色部がＥＰＤＭ相からなるマトリクスであり、黒色部がＰＡ１１相（ポリアミド系熱可塑性樹脂）からなる分散相である。
【００６８】
また、図４の各写真において、海島構造のモルフォロジーが観察され、島状のポリアミド系熱可塑性樹脂の粒子が、海状のＥＰＤＭからなるマトリクス中に微分散していた。写真中、大きい分散粒子は数１００ｎｍ程度であり、小さい分散粒子は数１０ｎｍ程度である。一辺の長さは１０μｍである。
実施例１〜実施例３は、ポリアミド系熱可塑性樹脂からなる粒子が、数十ｎｍサイズの小ドメインと数百ｎｍサイズの大ドメインの２種類混在するモルフォロジィーを有していた。比較例２は、ポリアミド系熱可塑性樹脂がナノ分散化されておらず、平均粒径が１０００ｎｍ以上と大きかった。
【００６９】
さらに、図５に示すように、実施例３は、摩耗面５０であるローラの外周面の溝形成部分に、摩耗面５０の摩耗による複数の微細な溝５１が形成されており、溝５１は摩擦時に紙から発生する微小な異物である紙粉５５を取り込める深さ及び幅であった。溝５１に紙粉５５が取り込まれ、摩耗面５０には紙粉５５が付着していなかった。よって、紙との擦動によりローラの外周面が摩耗し、摩耗面５０であるローラの外周面の溝形成部分に、通紙により、主に摩耗方向と略平行な溝５１が形成されていることが確認できた。
一方、比較例１は、摩耗面５０に溝が形成されておらず、紙粉５５が摩耗面の全体に付着していた。
【００７０】
詳細には、表１及び表２に示すように、実施例１〜実施例３の紙送りローラは、比較例１と比べて初期摩擦係数はより高い上に、いずれも通紙を繰り返すことにより、摩耗時に摩耗面に微細な溝と微小な突起が形成されたため、通紙後においても、比較例１、２に比べ、その高い摩擦係数が保持された。また、耐摩耗性及び圧縮永久歪みは同等であった。
【００７１】
一方、表２に示すように、比較例１、比較例２は、通紙により摩耗面であるローラの外周面に、微細な溝も微小な突起も形成されておらず、溝形成部分も摩擦係数維持部分も存在しなかったため、摩擦係数の低下を抑制できず、通紙前後の摩擦係数が不足し、紙送りローラとして不適であった。特に、比較例１は、ポリアミド系熱可塑性樹脂を用いなかったため、摩擦係数の低下が著しかった。また、比較例２は、通紙前後の摩擦係数が不足している上に、耐摩耗性及び圧縮永久歪みも悪く、紙送りローラとして不適であった。
【００７２】
【発明の効果】
以上の説明より明らかなように、本発明によれば、マトリクスの表面露出部分が摩耗時に溝形成部分とされると共に、マトリクスよりも耐摩耗性を有しナノ分散化された樹脂が突起として残存して摩擦係数維持部分とされる。このため、摩擦係数低下の原因となる異物が、摩耗時に溝形成部分に形成される溝に取り込まれ、紙等との接触面において紙粉等の異物を排除することができる。また、摩耗時に摩擦係数維持部分として形成される突起が搬送される紙等に対して引っ掻き効果を発揮する。よって、摩擦係数の低下を抑制することができ、また、紙等との接触面積を低減することもなく、長期に渡って、高摩擦係数を保持し耐久性を高めることができる。
【００７３】
従って、本発明の弾性部材は、紙送りローラ、その他、摩耗しても常に高い摩擦係数を必要とされる用途、例えば、タイヤ等に使用することができる。
【００７４】
さらに、本発明の弾性部材を用いた紙送りローラは、摩擦係数が高く、かつ高摩擦係数を保持することができると共に、良好な柔軟性をも有しているため、搬送性や耐久性に優れており、画像形成装置の紙送り機構に好適に用いることができる。特に、薄い紙やフィルム等の搬送物をピックアップし分離しながら紙送りをする必要があるインジェクションプリンタ、レーザプリンタ、静電式複写機、普通紙ファクシミリ装置、ＡＴＭ等の画像形成装置の給紙機構における紙送りローラとして好適である。
【図面の簡単な説明】
【図１】（Ａ）は本発明の実施形態の紙送りローラを示す斜視図、（Ｂ）は紙送りローラを給紙機構にセットした状態を示す概略図である。
【図２】上記紙送りローラの２００００枚通紙後の摩耗面の拡大模式図であり、（Ａ）は摩耗面の表面状態を示し、（Ｂ）（Ｃ）（Ｄ）は摩耗面の断面図である。
【図３】実施例３の通紙枚数毎の摩耗面のＳＰＭによる断面写真である。
【図４】ＳＰＭによるモルフォロジー観察写真である。
【図５】実施例３、比較例１の２００００枚通紙後の摩耗表面のＳＥＭによる観察写真である。
【図６】紙送りローラの摩擦係数を測定するための装置の概略図である。
【符号の説明】
１ 紙送りローラ
１０ 弾性部材
１０ａ 摩耗面
１１ マトリクス
１１Ａ 溝形成部分
１２ 樹脂
１２Ａ 摩擦係数維持部分
１２ａ 小ドメイン
１２ｂ 大ドメイン
Ｍ 溝
Ｔ 突起
Ｓ 紙
Ｓａ 紙粉（異物）[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an elastic member, a paper feed roller including the elastic member, and more particularly, to improving a surface state generated at the time of wear of the elastic member so that a friction coefficient can be maintained, and for an image forming apparatus such as an ink jet printer and a copying machine. When used as a paper feed roller, a reduction in friction coefficient due to the adhesion of paper powder is suppressed.
[0002]
[Prior art]
Purpose of picking up and separating paper and film and other conveyed materials in OA equipment such as inkjet printers, laser printers, electrostatic copiers, plain paper facsimile machines, and paper feed mechanisms such as automatic teller machines (ATMs). And a paper feed roller is used.
The paper feed roller requires a conveying force for conveying a conveyed object such as paper or film, and requires a certain coefficient of friction or more.However, foreign matter due to the conveyed object such as paper dust adheres during conveyance. There is a problem that the friction coefficient decreases.
[0003]
Therefore, conventionally, in order to prevent foreign matter of about several nm such as paper dust coming out of the conveyed object from adhering to the contact surface between the paper feed roller and the conveyed object, a groove portion such as a knurled groove having a depth and width of about several mm is used. It is provided on the outer peripheral surface of the paper feed roller. However, if a groove having a width of about several millimeters is provided on the outer peripheral surface of the paper feed roller, there is a problem that the contact area between the paper feed roller and the conveyed material is greatly reduced, and the friction coefficient is reduced. Further, when the depth of the groove becomes shallow due to wear, and the groove disappears due to repeated use, adhesion of foreign matter cannot be prevented, the friction coefficient is reduced, and durability is deteriorated. In recent years, the life of image forming apparatuses such as copying machines and printers has been prolonged, the required level of durability has been increased, and moreover, the number of parts has been reduced and the number of parts has been increased so that they are often used under high loads. Therefore, there is a demand for further improving the durability of the paper feed roller.
[0004]
Materials for forming a rubber roller and the like have been researched and developed, and various materials in which a resin component such as a polyamide-based thermoplastic resin is used as a matrix and a rubber component is dispersed have been proposed.
For example, in a thermoplastic elastomer composition proposed in Japanese Patent Application Laid-Open No. 2000-129047 (Patent Document 1), a polyamide-based elastomer is used as a matrix phase, and an ethylene-acrylate copolymer rubber component is used as a dispersed phase.
In the rubber composition proposed in JP-A-10-251452 (Patent Document 2), fine particles made of nylon are dispersed in a hydrogenated NBR elastomer matrix, and a functional group-containing ethylene copolymer is present. Is contained.
[0005]
[Patent Document 1]
JP 2000-129047 A
[0006]
[Patent Document 2]
JP-A-10-251452
[0007]
[Problems to be solved by the invention]
However, the composition of Patent Document 1 has a high overall hardness, a low friction coefficient, and a good abrasion resistance because the polyamide-based elastomer or the thermoplastic resin forms a matrix phase and the rubber forms a dispersed phase. Cannot be realized. In addition, there is a problem that the polyamide resin flows by melt-pressing, and phase separation proceeds. In particular, when used as a paper feed roller, there is a problem that the hardness is too high and a sufficient conveying force cannot be obtained, which is not suitable for practical use.
[0008]
Further, although the composition of Patent Document 2 has fine particles made of nylon dispersed in the composition, there is a problem that abrasion resistance is deteriorated depending on the dispersion state of the particles. For example, when used as a paper feed roller, there is a problem that a sufficient coefficient of friction cannot be obtained and a sufficient conveying force cannot be obtained, which is not suitable for practical use.
[0009]
The present invention has been made in view of the above-mentioned problems, and provides an elastic member having a high coefficient of friction, maintaining the high coefficient of friction, and having excellent durability, and a paper feed roller including the elastic member. That is the task.
[0010]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the present invention firstly provides a matrix made of an elastomer, in which a resin having wear resistance more than the matrix is nano-dispersed. In addition, the resin provides an elastic member having a configuration in which the resin remains as a protrusion and serves as a friction coefficient maintaining portion.
[0011]
In other words, when the surface of the elastic member is worn, the resin dispersed in the nano form has a smaller wear amount than the matrix resin, so that the matrix resin portion is worn to form a groove, and the dispersed resin is It remains as a projection.
The grooves formed take in foreign substances such as paper dust and prevent foreign substances from adhering to the exposed surface, while the remaining resin functions as a friction coefficient maintaining part, maintaining a high friction coefficient for a long time. Durability can be increased.
[0012]
Further, since the grooves and projections formed by the abrasion of the elastic member are very small, on the order of several nanometers to several hundreds of nanometers, the presence of the grooves and projections reduces the contact area with the friction object. And the friction coefficient can be maintained. Even if a part of the groove or projection disappears due to repeated wear, another new groove or projection is formed by further wear, so that the effect of suppressing the friction coefficient can be maintained.
Moreover, since the elastomer is a matrix, the elastic member of the present invention can obtain good flexibility over a long period of time. Therefore, it is possible to realize both a high friction coefficient and flexibility over a long period of time as well as the initial state.
Therefore, the elastic member of the present invention can be used for a paper feed roller and other applications that always require a high friction coefficient even when worn, for example, tires.
[0013]
The reason that the resin having more wear resistance than the matrix is nano-dispersed in the matrix composed of the elastomer with an average particle size of less than 1 μm is that if the average particle size is too large, the interface between the elastomer and the resin will crack at the time of wear. Is likely to occur, and the compression set becomes large.
In addition, the said average particle diameter is the value obtained by evaluating with a scanning probe microscope by the method mentioned later.
As a resin having abrasion resistance more than the above matrix, a high-polarity polyamide-based thermoplastic resin is preferable, and excellent in mechanical strength such as tear strength, a high coefficient of friction is obtained, and it has polarity, so that it has an affinity. The elastic member can also be excellent.
[0014]
By setting the volume ratio of the elastomer and the resin to (elastomer: resin) = (99.9: 0.1) to (87.5: 12.5), the groove forming portion and the friction coefficient are maintained during wear. The balance of the parts can be made very good, and grooves and projections can be formed in good condition by repeated wear.
If the volume fraction of the elastomer is less than the above range, the resin dispersed phase becomes dense, or the resin becomes a matrix phase, and good flexibility cannot be obtained. On the other hand, when the volume fraction of the elastomer is larger than the above range, the amount of the elastomer is too large, and the properties produced by the dispersion of the resin are impaired. The volume ratio is more preferably (99.0: 1.0) to (92.0 to 8.0).
In the case of oil-extended rubber, the volume of the elastomer is the sum of the rubber and the oil-extended oil. Similarly, in the case of an oil-extended resin, the volume of the resin is the sum of the resin and its oil-extended oil. In the case of using a plasticizer and a compatibilizer which are dissolved in both the rubber and the resin, the total volume is obtained by adding them. In addition, as the amount of the resin increases, the particle diameter tends to increase, and it becomes difficult to perform uniform fine dispersion.
[0015]
Further, in the elastic member of the present invention, it is preferable that the resin to be nano-dispersed is composed of two types: a small domain having a size of several tens nm and a large domain having a size of several hundred nm.
As a result of consideration from the results of the wear resistance test of the elastic member, it has been found that a small domain having a size of several tens nm improves the wear resistance, and a large domain having a size of several hundred nm improves the coefficient of friction. In particular, when a large domain having a size of several hundred nm remains as a projection and is used as a friction coefficient maintaining portion, the scratching effect is higher, and the performance of maintaining the friction coefficient is higher. As described above, when two types of domains, large and small, are mixed, wear resistance can be improved, a high coefficient of friction can be realized, and both performances can be improved in a well-balanced manner.
[0016]
Specifically, a small domain having an average particle size of several tens nm is about 10 nm to 100 nm, and a large domain having an average particle diameter of several hundred nm is about 100 nm to 1000 nm. If the average particle size is in the above range, shapes such as sphere, fiber, column, and ellipse are not specified. Further, it is preferable that the small domain and the large domain are uniformly distributed without being unevenly distributed.
The volume ratio of the small domain to the large domain is preferably (small domain: large domain) = (30:70) to (70:30).
The reason for setting the above range is that if there are fewer small domains than the above range, it is difficult to improve the wear resistance. On the other hand, if there are more small domains than the above range, it is difficult to improve the friction coefficient.
[0017]
Nylon 6, nylon 66 can be used as the polyamide-based thermoplastic resin because it is a general-purpose resin and relatively inexpensive, and can be efficiently made compatible by grafting to a maleic acid-modified polymer using a terminal amino group. Nylon resin such as nylon 11, nylon 12, and the like can be suitably used. Further, the polyamide thermoplastic resin may be oil-extended to improve the conveying force within a range in which bleed does not occur. The amount of the oil-extended plasticizer is 5 to 150 parts by weight based on 100 parts by weight of the resin. Parts by weight, preferably 10 parts by weight or more and 100 parts by weight or less.
[0018]
It is preferable to use a maleic acid-modified polymer as a compatibilizer between the elastomer and the polyamide-based thermoplastic resin. By using the compatibilizing agent, usually, a diene rubber having a low compatibility or an elastomer such as EPM or EPDM and a small amount of a polyamide thermoplastic resin can be effectively alloyed.
In particular, by using the maleic acid-modified polymer, the portion of maleic anhydride contained in the molecule of the maleic acid-modified polymer reacts with the terminal amino group of the polyamide-based thermoplastic resin to form the grafted compatibilizer. For the production, it is possible to very efficiently compatibilize a diene rubber or an elastomer such as EPM or EPDM with a polyamide thermoplastic resin.
[0019]
Examples of the maleic acid-modified polymer include maleic acid-modified ethylene ethyl acrylate (EEA), maleic acid-modified ethylene propylene rubber, maleic acid-modified ethylene propylene diene rubber, and maleic acid-modified styrene-based thermoplastic elastomer. When an ethylene propylene rubber or a maleic acid-modified styrene-based thermoplastic elastomer is used, deterioration of physical properties is small, and a better paper feed roller can be manufactured. Among these, maleic acid-modified ethylene propylene rubber is particularly preferably used.
[0020]
As described above, when a compatibilizer is blended to enhance the compatibility between the elastomer and the polyamide-based thermoplastic resin, the polyamide-based thermoplastic resin becomes nano-dispersed even after the melt pressing and molding involving a crosslinking reaction. . Therefore, even if it is melt-pressed, the polyamide-based thermoplastic resin flows and the phase separation does not progress, and a good dispersion state can be obtained.
[0021]
Also, when the compatibilizer and the resin react at the interface between the elastomer and the resin, a graft polymer is formed. Then, the graft polymer extracted from the interface becomes a small domain having a size of several tens nm, and the domain of the resin remaining without being extracted becomes a large domain having a size of several hundred nm. As a result, two types of small domains having an average particle size of several tens of nanometers and large domains having a size of several hundreds of nanometers are mixed.
[0022]
The compatibilizer is preferably blended in a ratio of 0.1 to 1.0 times the weight of the polyamide-based thermoplastic resin (the resin component excluding oil in the case of an oil-extended resin). More preferably, it is 0.2 times or more and 0.7 times or less.
The reason for setting the above range is that if the amount is less than the above range, the amount of the compatibilizer that reacts at the interface of the polyamide-based thermoplastic resin is insufficient, and it is difficult to be finely dispersed. On the other hand, if the amount is larger than the above range, the properties (physical properties) of the material may be affected by the compatibilizer, and the compatibilizer is often expensive, which tends to increase the cost.
[0023]
As the elastomer, conventionally known rubbers and / or thermoplastic elastomers can be used, but it is preferable to use diene rubber or one or more rubbers selected from EPM and EPDM.
In particular, as the elastomer, the main chain is composed of a saturated hydrocarbon, and the main chain does not contain a double bond. Therefore, even when exposed to an environment such as a high-concentration ozone atmosphere or light irradiation for a long time, the molecular main chain is not cleaved. It is preferable to use ethylene propylene diene copolymer rubber (EPDM) because it hardly occurs and the weather resistance is excellent.
In addition, one or more of styrene butadiene rubber (SBR), isoprene rubber (IR), natural rubber (NR), butadiene rubber (BR), acrylonitrile butadiene rubber (NBR), ethylene propylene rubber (EPR) and the like may be used. it can. In addition, you may use various thermoplastic elastomers, such as a styrene type and an olefin type, as said elastomer.
By using a diene rubber or EPM or EPDM together with an oil extending or softening agent, a low hardness can be realized and a high conveying force can be realized. These diene rubbers, EPM and EPDM can be easily crosslinked with an organic peroxide or the like.
[0024]
Crosslinking is performed by at least one crosslinking method selected from sulfur crosslinking, peroxide crosslinking, and resin crosslinking. Of these, peroxide crosslinking or resin crosslinking is preferred because blooming is less likely to occur and the compression set is reduced. Note that sulfur crosslinking may be used.
[0025]
As the peroxide used for peroxide crosslinking, 2,5-dimethyl-2,5-di (t-butylperoxy) hexine-3, dicumyl peroxide, 1,1-bis (t-butyl) Peroxy) 3,3,5-trimethylcyclohexane, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, benzoyl peroxide, 2-5 dimethyl 2-5 di (benzoyl per Oxy) hexane, di-t-butylperoxy-m-diisopropylbenzene, t-butylperoxybenzoate, t-butylperoxycumene, di-t-butylperoxide and the like. Various peroxides can be selected according to the melting point and softening point of the polyamide thermoplastic resin such as the polyamide thermoplastic resin, and the residence time in the kneader.
Usually, the amount of the peroxide is preferably from 0.1 to 30 parts by weight, more preferably from 0.5 to 10 parts by weight, per 100 parts by weight of the elastomer (the rubber excluding oil in the case of oil-extended rubber). Particularly preferred is not more than parts by weight.
[0026]
When performing peroxide crosslinking, triallyl isocyanurate (TAIC), triallyl cyanurate (TAC), and triarylcyanurate (TAC) are used for the purpose of improving and adjusting various mechanical properties such as fatigue properties, and improving the crosslinking density. Cross-linking aids such as polyfunctional monomers such as methylolpropane trimethacrylate (TMPT), ethylene glycol dimethacrylate (EDMA), and N-N'-m-phenylenebismaleimide may be used. It may be used in combination with crosslinking or sulfur crosslinking.
[0027]
A resin cross-linking agent is used in resin cross-linking, but the resin cross-linking agent is a synthetic resin that causes a cross-linking reaction to rubber by heating or the like, and does not cause a problem of bloom caused when sulfur and a vulcanization accelerator are used in combination. It is preferred. In particular, when a phenol resin is used as the resin crosslinking agent, the paper feeding performance can be improved. Other resin crosslinking agents include melamine / formaldehyde resin, triazine / formaldehyde condensate, hexamethoxymethyl / melamine resin, and the like.
Usually, the compounding amount of the resin crosslinking agent is preferably 1 part by weight or more and 50 parts by weight or less, and more preferably 6 parts by weight or more and 15 parts by weight or less with respect to 100 parts by weight of the elastomer (in the case of oil-extended rubber, the rubber content excluding oil). Particularly preferred.
[0028]
The cross-linking or partial cross-linking (dynamic cross-linking) in the present invention may be performed in the presence of a halogen such as chlorine, bromine, fluorine and iodine. In order to make halogen present at the time of dynamic crosslinking, a halogenated resin crosslinking agent may be used, or a halogen-donating substance may be blended in the elastic member. Examples of the halogenated resin crosslinking agent include those obtained by halogenating each of the above addition condensation type resins.
In addition, a crosslinking aid (activator) may be used to appropriately perform a crosslinking reaction. A metal oxide is used as a crosslinking assistant, and zinc oxide and zinc carbonate are particularly preferable.
[0029]
The resin is preferably alloyed and finely dispersed by a reactive blending technique. The reactive blending technique is a technique for simultaneously proceeding a chemical reaction leading to melt-kneading and compatibilization, which can provide excellent mechanical properties and provide a new function to a material.
[0030]
The elastic member of the present invention preferably has a hardness of 15 to 60 degrees as measured by a JIS6253 A-type hardness tester. Thereby, grooves and projections are easily formed at the time of wear, and both flexibility and a high coefficient of friction can be achieved. In particular, when used as a paper feed roller, the hardness is preferably in the range of 15 to 60 degrees, preferably 20 to 55 degrees, and more preferably 20 to 50 degrees. Within this range, even if the paper feed roller is pressed against the paper or film with a relatively small pressing force, the paper feed roller is sufficiently deformed, and a large contact area with the paper or film can be obtained.
[0031]
Examples of the softener include oils and plasticizers, and those having low polarity are particularly preferably used. As the oil, for example, a mineral oil such as a paraffinic, naphthenic, or aromatic aromatic oil, or a known synthetic oil composed of a hydrocarbon oligomer or a process oil can be used. As the synthetic oil, for example, an oligomer of α-olefin, an oligomer of butene, and an amorphous oligomer of ethylene and α-olefin are preferable. In particular, paraffinic oil is preferable because it has low volatility and is easy to handle and can reliably add a fixed amount.
As the plasticizer, for example, dioctyl phthalate (DOP), dibutyl phthalate (DBP), dioctyl sepate (DOS), dioctyl adipate (DOA), tricresyl phosphate and the like can be used as long as the compatibility with the rubber is not deteriorated. One or more species can be used.
[0032]
It is preferable that 10 to 600 parts by weight of a softening agent is added to 100 parts by weight of the elastomer.
Specifically, when the softener is oil, the amount is preferably 15 parts by weight or more and 600 parts by weight or less, and more preferably 25 parts by weight or more and 400 parts by weight or less with respect to 100 parts by weight of rubber.
If the oil is less than 15 parts by weight, the hardness may be too high, for example, it is difficult to obtain an appropriate hardness as a paper feed roller or the like. On the other hand, if it is more than 600 parts by weight, oil bleeds from the surface of the dynamically cross-linked product, or the oil causes cross-linking inhibition, and there is a problem that the rubber component is not sufficiently cross-linked and physical properties are deteriorated. is there.
When the softener is a plasticizer, the amount is 10 parts by weight or more and 500 parts by weight or less, preferably 15 parts by weight or more and 400 parts by weight or less with respect to 100 parts by weight of rubber.
[0033]
Further, in addition to the above-mentioned compounding agents, an antioxidant, a wax and the like can be added to the elastic member, if necessary. Examples of the antioxidant include imidazoles such as 2-mercaptobenzimidazole, phenyl-α-naphthylamine, N, N-di-β-naphthyl-P-phenylenediamine, and N-phenyl-N′-isopropyl-P-. Examples include amines such as phenylenediamine, phenols such as di-t-butyl-p-cresol, and styrenated phenol. In addition, it is preferable to use a plurality of types of antioxidants.
The compounding amount of the anti-aging agent is preferably 0.5 parts by weight or more and 10 parts by weight or less, more preferably 1 part by weight or more and 3 parts by weight or less based on 100 parts by weight of the elastomer (the rubber component excluding oil in the case of oil-extended rubber). Particularly preferred.
[0034]
The rubber is preferably an oil-extended rubber having a molecular weight as large as possible. Specific examples thereof include Esplen 670F manufactured by Sumitomo Chemical Co., Ltd., Esplen 601F, and Keltan 509 × 100 manufactured by Idemitsu DMS.
When the rubber is oil-extended, the amount of oil to be oil-extended is from 15 parts by weight to 600 parts by weight, preferably from 25 parts by weight to 400 parts by weight, based on 100 parts by weight of the rubber, from the viewpoint of hardness and conveying force. It is good to be the following.
[0035]
In order to improve the mechanical strength of the elastic member, a filler can be added as needed. Examples of the filler include powders of silica, carbon black, clay, talc, calcium carbonate, dibasic phosphite (DLP), basic magnesium carbonate, alumina and the like. When a filler is blended, it is preferable that the filler be 30% by weight or less based on the entire elastic member. This is because although the compounding of the filler is effective for improving the tensile strength and the tearing strength of the rubber, if the compounding is too large, the flexibility of the rubber is greatly reduced.
[0036]
Further, the elastomer is preferably compounded as a master batch in which a rubber or the like, a plasticizer, and, if necessary, a compatibilizer, an antioxidant, and the like are mixed by a kneader or the like. Thereby, workability is improved and dispersibility can be improved. It is preferable that the polyamide-based thermoplastic resin is similarly compounded as a master batch.
[0037]
The resin masterbatch is kneaded with a compatibilizer or the like in a polyamide thermoplastic resin such as a polyamide thermoplastic resin using a twin-screw extruder, a kneader or a Banbury mixer, for example, at 160 ° C to 280 ° C. The mixture is kneaded for 20 minutes to 20 minutes, and then pelletized by a usual method.
For example, a rubber master batch is prepared by using a twin screw extruder, a kneader or a Banbury mixer, etc., and, if necessary, a diene rubber or a rubber component such as EPM, EPDM, etc., if necessary, a plasticizer such as paraffin oil, a compatibilizer, an aging agent. An inhibitor, a filler, and the like are kneaded and kneaded at 20 ° C. to 250 ° C. for 1 minute to 20 minutes, and pelletized by a usual method.
The compatibilizer is kneaded at a high temperature into the resin master batch, and when it is a maleic acid-modified polymer, it is first reacted with the terminal amino group of the polyamide-based thermoplastic resin, and then the polymer blend is mixed. It may be performed, or may be added by dry blending to a rubber masterbatch or a resin masterbatch during polymer blending.
[0038]
Secondly, the present invention provides a paper feed roller comprising the above elastic member and used in an image forming apparatus.
Specifically, since the outer peripheral surface of the roller having a substantially cylindrical shape or a cylindrical shape comes into sliding contact with the drum at the time of paper feeding and wears, the surface exposed portion of the matrix on the outer peripheral surface of the roller becomes a groove forming portion, and the resin is removed. The protrusion remaining on the outer peripheral surface of the roller serves as a friction coefficient maintaining portion. The above-mentioned groove is a groove substantially parallel to the wear direction, though it depends on the resin dispersion shape.
The above-described paper feed roller can realize a high coefficient of friction and low hardness, and also maintains a high coefficient of friction even after repeated use, provides a higher conveying force, and has excellent durability. .
[0039]
If the volume ratio of the elastomer is less than 87.5, the paper feed roller becomes too high in hardness to provide a sufficient conveying force, and is not suitable for practical use. On the other hand, when the volume fraction of the elastomer is more than 99.9, the characteristics of high conveying force generated by the polyamide-based thermoplastic resin are impaired.
[0040]
The paper feed roller is formed in a cylindrical shape, and has a thickness of 0.5 mm to 20 mm, preferably 1 mm to 5 mm. If the thickness is smaller than 0.5 mm, it is difficult to form a large contact area with the paper even if the paper feed roller is deformed. On the other hand, if the wall thickness exceeds 20 mm, the pressing force of the paper feed roller against the paper must be increased to deform the roller, and the mechanism for pressing the paper feed roller against the paper becomes large. is there. The shaft core is pressed into the hollow portion of the paper feed roller or fixed by bonding with an adhesive.
[0041]
For forming the paper feed roller, for example, a rubber masterbatch pellet, a resin masterbatch pellet, zinc white, an antioxidant, a filler, and other necessary additives are charged into a twin-screw extruder. The mixture is kneaded for 1 minute to 20 minutes while heating at a temperature of 0 ° C. to blend the elastomer and the polyamide-based thermoplastic resin and then extrude. Next, the extruded material is kneaded with a cross-linking agent by an open roll, and then subjected to hot press molding at 170 ° C. to 230 ° C. After that, the sheet is cut to a required size to form a paper feed roller. The surface of the paper feed roller may be polished and used as needed.
[0042]
The paper feed roller includes rollers (nudger (used as one), feed (used as a retard and a set of two described later)) which are rotated in the paper feed direction for the purpose of feeding paper, and weight of the paper. There are three types of rollers (retards) that are used by applying a torque in the direction opposite to the paper feeding direction for the purpose of preventing the paper feeding, but can be used for each type of roller. The shape of the paper feed roller can be various shapes such as a cylindrical shape and other irregularly shaped rollers such as a D-shape.
[0043]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1A shows a cylindrical paper feed roller 1 formed using an elastic member 10 of the present invention, and a shaft core 2 is press-fitted into a hollow portion thereof.
The paper feed roller 1 is set in a paper feed mechanism of a printer as shown in FIG. The paper feed mechanism includes a separation sheet 4 on an upper surface of a paper feed tray 3, a paper feed roller 1 is disposed on the upper part of the separation sheet 4, and a spring (not shown) abuts on a lower surface of the tray 3. The separation sheet 4 is urged toward the paper feed roller 1. The leading end of the paper S is sandwiched between the separation sheet 4 and the paper feed roller 1, and the paper feed roller 1 is rotated in the direction of arrow R in the drawing, so that the paper S is directed toward the image forming mechanism one by one. And sent out.
Therefore, the paper feed roller 1 is urged by the separation sheet 4 and comes into sliding contact with the paper being conveyed while being pressed against the paper feeding roller 1 side. It will go.
[0044]
FIG. 1 is an enlarged schematic view of a wear surface 10a of an elastic member 10 which is the outer peripheral surface of the paper feed roller 1 after passing 20,000 sheets of plain paper.
[0045]
The elastic member 10 forming the paper feed roller 1 has a matrix 11 made of an elastomer, in which a resin 12 having a higher abrasion resistance than the matrix 11 is nano-dispersed. In addition to the formation portion 11A, the resin 12 remains as the protrusion T and serves as the friction coefficient maintaining portion 12A.
In the present embodiment, oil-extended EPDM (rubber: oil = 1: 1) is used as the elastomer, and an oil, which is a polyamide-based thermoplastic resin having more wear resistance than oil-extended RPDM, is contained in a matrix composed of the oil-extended EPDM. The expanded nylon resin is nano-dispersed with an average particle size of less than 1 μm.
[0046]
The groove-forming portion 11A made of an elastomer is a random portion because it is a portion other than the nano-dispersed resin, but the fine groove M formed by abrasion due to repeated friction with the paper S is formed. Is formed substantially parallel to the rotation direction of the paper feed roller 1 which is mainly the wear direction L, and is formed substantially evenly over the entire surface of the roller serving as the wear surface 10a. The depth, width, and length of the groove M are on the order of several nanometers to several hundreds of nanometers, and are depths and widths that can take in paper powder Sa, which is a minute foreign matter generated from paper.
The protrusions T which become the friction coefficient maintaining portions 12A are formed so as to be substantially uniformly scattered on the entire surface of the wear surface 10a, and the grooves M and the protrusions T are formed on the wear surface 10a in a well-balanced manner.
[0047]
On the other hand, the nano-dispersed resin 12 is left as minute projections T because the wear is delayed as compared with the elastomer. The height and diameter of the projection T are on the order of several nm to several hundred nm.
As shown in FIG. 2D, the resin 12 has a small domain 12a having an average particle size of about 10 nm to 100 nm and a size of several tens nm, and a large domain 12b having an average particle size of about 100 nm to 1000 nm and having a size of several hundred nm. And are uniformly distributed in the matrix 11 without being unevenly distributed. The volume ratio between the small domain 12a and the large domain 12b is almost uniform with little variation, and (small domain 12a: large domain 12b) = (50:50).
[0048]
In this embodiment, the volume ratio of EPDM to be a matrix and the polyamide-based thermoplastic resin is 98.0: 2.0, and a maleic acid-modified polymer is used as a compatibilizer. The compatibilizer is used in a weight 0.25 times the weight of the polyamide-based thermoplastic resin, and is alloyed and finely dispersed by a reactive blending technique. The hardness is 26 degrees as measured by a JIS6253 A-type hardness tester.
[0049]
The paper feed roller 1 formed from the elastic member 10 is manufactured by the following method. First, a compatibilizer, an antioxidant, and the like are kneaded in an oil-extended EPDM by a kneader, and kneaded at a temperature of 20 ° C to 250 ° C for 1 minute to 20 minutes. Thereafter, the rubber composition is pelletized by a usual method to produce a rubber masterbatch pellet. The oil and rubber components in the oil-extended EPDM have a weight ratio of 1: 1.
Next, a compatibilizing agent and the like are kneaded into the oil-extended nylon resin by a kneader, and kneaded at a temperature of 160 ° C to 280 ° C for 1 minute to 20 minutes while heating. Thereafter, the thermoplastic resin composition is pelletized by an ordinary method to prepare pellets of a resin master batch.
[0050]
The required additives such as the rubber masterbatch pellets, resin masterbatch pellets, zinc white, antioxidant, and filler are charged into a twin-screw extruder HTM38 (manufactured by Ibec Co., Ltd.). While heating at a temperature, the mixture is kneaded for 1 to 20 minutes to blend the rubber and the resin and then extrude. Next, a peroxide crosslinking agent is kneaded with the extruded kneaded rubber by an open roll, followed by hot press molding at 170 to 230 ° C. After that, the sheet is cut to a required size to form a paper feed roller 1.
[0051]
In the paper feed roller 1 formed by the elastic member 10, the surface exposed portion of the matrix 11 becomes a groove forming portion 11A when worn, and extremely minute grooves M on the nano level are formed on the worn surface 10a when worn. For this reason, paper dust Sa, which is a foreign substance causing a decrease in friction coefficient, is taken into the groove M, and the paper powder Sa, which is a foreign substance, can be removed from the abraded surface 10a that is in sliding contact with the paper S.
The resin 12 nano-dispersed in the matrix 11 is used as a friction coefficient maintaining portion 12A at the time of wear, and very minute projections T at the nano level are formed on the wear surface 10a at the time of wear. For this reason, the protrusion T exerts a scratching effect on the friction object, and a high friction coefficient can be realized without reducing the contact area with the friction object. Even if the paper feed roller wears repeatedly due to sliding contact with the paper S, the groove M and the protrusion T are present on the wear surface 10a, so that a decrease in the coefficient of friction can be suppressed and a high coefficient of friction can be maintained. be able to.
For this reason, the paper feed roller 1 can obtain high conveyance force and excellent durability even when used repeatedly, and is suitably used as a paper feed roller of an image forming apparatus such as an ink jet printer or a copying machine.
[0052]
In addition to the above embodiment, various elastomers such as EPM and diene rubber, or various thermoplastic elastomers such as styrene and olefin can be used as the elastomer. In addition, the blending type and blending amount of the polyamide-based thermoplastic resin and the compatibilizing agent can be appropriately set. In addition, you may bridge | crosslink by resin bridge | crosslinking, sulfur bridge | crosslinking, etc.
[0053]
Hereinafter, Examples 1 to 3 and Comparative Examples 1 to 4 of the paper feed roller using the elastic member of the present invention will be described in detail.
The paper feed roller of the present invention was formed by using the respective compounding materials shown in the following Tables 1 and 2 by hot pressing in the same manner as in the above embodiment, and then formed into an outer diameter of 19.7 mm, an inner diameter of 10 mm, and a width of 10 mm. The sheet was cut to produce a cylindrical paper feed roller.
[0054]
[Table 1]

[0055]
[Table 2]

[0056]
The numerical values of each composition in the table are parts by weight. In the table, as the rubber 1, 200 parts by weight of 100% oil-extended EPDM (100 parts by weight of rubber + 100 parts by weight of oil) was used. Oil-extended nylon 11 was used as the polyamide resin.
[0057]
(Examples 1 to 3)
In Examples 1 to 3, the resin having wear resistance than the matrix is nano-dispersed in the matrix composed of the elastomer, and the surface exposed portion of the matrix is formed as a groove forming portion at the time of wear, and the resin remains as a protrusion. The configuration is such that the friction coefficient is maintained.
Specifically, as shown in Table 1, together with a compatibilizer, 100% oil-extended EPDM is used as an elastomer serving as a matrix, and an oil-extended polyamide-based thermoplastic resin is used as a polyamide-based thermoplastic resin serving as a dispersed phase. Nylon 11 was used at the above volume ratio.
[0058]
The particle size distribution of the polyamide-based thermoplastic resin is shown below. All were produced by reactive blending.
In Example 1, small domains (10 to 100 nm): large domains (100 to 1000 nm) = 40: 60.
In Example 2, small domains (10 to 100 nm): large domains (100 to 1000 nm) = 50: 50.
In Example 3, small domains (10 to 100 nm): large domains (100 to 1000 nm) = 60: 40.
[0059]
(Comparative Example 1)
Comparative Example 1 did not use a polyamide-based thermoplastic resin, and used only the same 100% oil-extended EPDM rubber matrix as in the example.
(Comparative Example 2)
In Comparative Example 2, the polyamide-based thermoplastic resin was dispersed at an average particle size of 1 μm or more without using the compatibilizer, and no reactive blending was performed. That is, the resin was not nano-dispersed.
[0060]
The paper feed rollers of Examples 1 to 3 and Comparative Examples 1 and 2 were subjected to the method described below to determine the particle diameter, initial friction coefficient, friction coefficient and abrasion amount, hardness and compression of the polyamide-based thermoplastic resin after passing 30,000 sheets. Evaluation and measurement of permanent set were performed. The results are shown in Tables 1 and 2.
[0061]
(Particle diameter of polyamide-based thermoplastic resin)
The paper feed rollers of Examples 1 to 3 and Comparative Example 2 were observed using a scanning probe microscope SPM (Scanning Probe Microscope) to evaluate the morphology of the material and the particle size of the polyamide-based thermoplastic resin. In Example 3, the cross section of the outer peripheral surface of the roller after passing 0, 10,000, 20,000, and 30,000 sheets was also observed. FIG. 3 shows a cross-sectional photograph of the worn surface for each number of sheets passed according to the third embodiment. The length of one side is 5 μm. FIG. 4 shows the morphology of the elastomer material used for the paper feed rollers of Examples 1 to 3 and Comparative Example 2.
[0062]
(Observation of roller outer peripheral surface after paper passing)
Regarding Example 3 and Comparative Example 1, the outer peripheral surface of the roller after passing 20,000 sheets was observed with a scanning electron microscope (SEM) (Scanning Electron Microscope). The observation photograph is shown in FIG.
[0063]
(Evaluation of friction coefficient and wear amount)
The coefficient of friction was measured by the following method shown in FIG. That is, A4 size PPC paper (manufactured by Fuji Xerox Office Supply Co., Ltd.) 24 connected to the load cell 25 is sandwiched between the paper feed roller 21 and the plate (separation sheet) 23, and is indicated by a black arrow in FIG. Thus, the load W (W = 250 gf) was applied to the rotating shaft 22 of the paper feed roller 21, and the paper feed roller 21 was pressed against the plate 23. Next, under the conditions of a temperature of 22 ° C. and a humidity of 55%, the paper feed roller 21 is rotated at a peripheral speed of 300 mm / sec in a direction shown by a solid arrow a in FIG. The force F (gf) generated in the direction indicated by the white arrow in the middle was measured by the load cell 25. Then, from the measured value F (gf) and the load W (250 gf), a friction coefficient μ was obtained from the following equation. The measurement of the friction coefficient was performed at the start of paper passing (initial friction coefficient) and at the end of the passing of 30,000 sheets, respectively.
Further, the abrasion amount (mg) was obtained by measuring the weight of each paper feed roller before and after the completion of the passing of 30,000 sheets.
The value of the coefficient of friction after passing 30,000 sheets by the above measurement is excellent when 1.7 or more is excellent, 1.5 or more is suitable, and less than 1.5 is inappropriate.
[0064]
(Equation 1)
μ = F (gf) / W (gf)
[0065]
(Measurement of hardness)
The hardness of the paper feed roller was measured with an A-type hardness meter according to JIS6253.
[0066]
(Measurement of compression set)
The compression set of the paper feed roller was measured according to JIS-K6301. The numerical unit was%. The compression set is preferably from 0 to 30.
[0067]
As shown in FIG. 3, in Example 3, in the enlarged photographs of 10,000, 20,000, and 30,000 sheets of paper passing, the abrasion surface 30 has a microscopic surface made of a polyamide-based thermoplastic resin localized by abrasion. The projections 32 remained and were scattered as a friction coefficient maintaining portion. Therefore, it was confirmed that the outer peripheral surface of the roller was worn due to the contact with the paper, and the projection 32 was formed as a friction coefficient maintaining portion on the outer peripheral surface of the roller, which is the abraded surface 30, by passing the paper.
3 and 4, the orange portion is a matrix composed of an EPDM phase, and the black portion is a dispersed phase composed of a PA11 phase (a polyamide-based thermoplastic resin).
[0068]
In each photograph of FIG. 4, the morphology of the sea-island structure was observed, and the island-like polyamide-based thermoplastic resin particles were finely dispersed in the sea-like EPDM matrix. In the photograph, large dispersed particles are about several hundred nm, and small dispersed particles are about several tens nm. The length of one side is 10 μm.
In Examples 1 to 3, particles made of a polyamide-based thermoplastic resin had a morphology in which two types of small domains having a size of several tens of nm and large domains having a size of several hundred nm were mixed. In Comparative Example 2, the polyamide-based thermoplastic resin was not nano-dispersed, and the average particle size was as large as 1000 nm or more.
[0069]
Further, as shown in FIG. 5, in the third embodiment, a plurality of fine grooves 51 due to wear of the wear surface 50 are formed in the groove forming portion on the outer peripheral surface of the roller, which is the wear surface 50. The depth and width were such that paper dust 55, which is a minute foreign matter generated from paper during friction, could be taken in. The paper dust 55 was taken into the groove 51, and the paper dust 55 did not adhere to the wear surface 50. Therefore, the outer peripheral surface of the roller is worn by the rubbing with the paper, and a groove 51 substantially parallel to the abrasion direction is formed by paper passing in the groove forming portion of the outer peripheral surface of the roller, which is the abraded surface 50. That was confirmed.
On the other hand, in Comparative Example 1, no groove was formed on the worn surface 50, and the paper dust 55 adhered to the entire worn surface.
[0070]
More specifically, as shown in Tables 1 and 2, the paper feed rollers of Examples 1 to 3 have a higher initial friction coefficient than Comparative Example 1 and all of them have repeated paper passing. Also, since fine grooves and fine projections were formed on the wear surface during wear, even after passing the paper, the higher friction coefficient was maintained as compared with Comparative Examples 1 and 2. The abrasion resistance and compression set were equivalent.
[0071]
On the other hand, as shown in Table 2, in Comparative Example 1 and Comparative Example 2, neither fine grooves nor fine protrusions were formed on the outer peripheral surface of the roller, which was the abraded surface due to the paper passing, and the groove-formed portion had friction. Since there was no coefficient maintaining portion, the decrease in the coefficient of friction could not be suppressed, and the coefficient of friction before and after sheet passing was insufficient, making the sheet unsuitable as a paper feed roller. In particular, Comparative Example 1 did not use a polyamide-based thermoplastic resin, so that the friction coefficient was significantly reduced. In Comparative Example 2, the friction coefficient before and after the paper passing was insufficient, and the abrasion resistance and the compression set were also poor.
[0072]
【The invention's effect】
As apparent from the above description, according to the present invention, the surface exposed portion of the matrix is formed as a groove forming portion at the time of abrasion, and the nano-dispersed resin which is more wear-resistant than the matrix and remains as projections Thus, the friction coefficient is maintained. For this reason, the foreign matter which causes a reduction in the friction coefficient is taken into the groove formed in the groove forming part at the time of abrasion, and the foreign matter such as paper dust can be eliminated from the contact surface with the paper or the like. Further, a projection formed as a friction coefficient maintaining portion at the time of abrasion exerts a scratching effect on paper or the like being conveyed. Therefore, a decrease in the coefficient of friction can be suppressed, and a high friction coefficient can be maintained and durability can be increased over a long period of time without reducing the contact area with paper or the like.
[0073]
Therefore, the elastic member of the present invention can be used for a paper feed roller and other applications that always require a high friction coefficient even when worn, for example, tires.
[0074]
Furthermore, the paper feed roller using the elastic member of the present invention has a high coefficient of friction, can maintain a high coefficient of friction, and has a good flexibility, so that it can be transported and durable. It is excellent and can be suitably used for a paper feeding mechanism of an image forming apparatus. In particular, paper feed mechanisms for image forming devices such as injection printers, laser printers, electrostatic copiers, plain paper facsimile machines, and ATMs that need to pick up and transport paper such as thin paper and film while separating them. It is suitable as a paper feed roller in.
[Brief description of the drawings]
FIG. 1A is a perspective view showing a paper feed roller according to an embodiment of the present invention, and FIG. 1B is a schematic view showing a state where the paper feed roller is set in a paper feed mechanism.
FIG. 2 is an enlarged schematic view of a worn surface after 20,000 sheets have been passed by the paper feed roller, where (A) shows a surface state of the worn surface, and (B), (C), and (D) are cross sections of the worn surface. FIG.
FIG. 3 is a cross-sectional photograph by SPM of a worn surface for each number of sheets passed in Example 3.
FIG. 4 is a morphology observation photograph by SPM.
FIG. 5 is an SEM observation photograph of a worn surface of Example 3 and Comparative Example 1 after passing 20,000 sheets.
FIG. 6 is a schematic view of an apparatus for measuring a coefficient of friction of a paper feed roller.
[Explanation of symbols]
1 Paper feed roller
10 Elastic members
10a Wear surface
11 matrix
11A Groove forming part
12 resin
12A Friction coefficient maintaining part
12a Small domain
12b large domain
M groove
T protrusion
S paper
Sa Paper powder (foreign matter)

Claims (6)

In a matrix composed of an elastomer, a resin having abrasion resistance than the matrix is nano-dispersed,
An elastic member having a structure in which a surface exposed portion of the matrix is formed as a groove forming portion at the time of wear, and the resin is left as a projection and serves as a friction coefficient maintaining portion. A high-polarity polyamide-based thermoplastic resin is used as the resin, and a volume ratio of the elastomer to the resin (elastomer: resin) is 99.9: 0.1 to 87.5: 12.5. Item 2. The elastic member according to Item 1. The elastic member according to claim 1 or 2, wherein the resin to be nano-dispersed comprises two types: a small domain having a size of several tens of nanometers and a large domain having a size of several hundreds of nanometers. 4. The elasticity according to claim 2, wherein nylon is used as the polyamide-based thermoplastic resin, and a maleic acid-modified polymer is used as a compatibilizer between the polyamide-based thermoplastic resin and the elastomer. Element. The elastic member according to any one of claims 1 to 4, wherein the elastic member is crosslinked with sulfur, peroxide, or resin. A paper feed roller comprising the elastic member according to claim 1 and used in an image forming apparatus.

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