JP3570458B2 - Composition for producing urethane foam, elastic material and elastic member - Google Patents

Description

（但し、ｍ＝５〜２５、ｎ＝０〜１０であり、ａ＝２５〜１００、ｂ＝５〜４０である。ＥＯは酸化エチレン、ＰＯは酸化プロピレンを示す。）
【００１４】
即ち、本発明者らは、シリコーン整泡剤として式（１）のシリコーン整泡剤を用いることにより、これはその末端に反応性のある水酸基を有するため、主材である２個以上の活性水素を有する化合物（ポリオール成分）と２個以上のイソシアネート基を有する化合物（イソシアネート成分）の反応の際に同時に架橋されるので、ローラ等の部材に使用した場合にも接触する相手部材を汚染することがなく、均一なセル径を有するウレタンフォームが得られること、更に本構造の整泡剤はウレタン原料に対して適度の界面活性効果を有するだけでなく、界面活性効果の持続性にも優れ、このため機械的撹拌により泡立てて得られたフォームが低密度で、セル径の小さな範囲のものを得ることができることを知見し、本発明を完成するに至った。
【００１５】
以下、本発明につき更に詳述すると、本発明のウレタンフォーム製造用組成物は、２個以上の活性水素を有する化合物（ポリオール成分）、２個以上のイソシアネート基を有する化合物（イソシアネート成分）及び整泡剤、更に必要に応じて導電性付与材料などを含む。
【００１６】
ここで、ポリオール成分としては、一般の軟質ポリウレタンフォームやウレタンエラストマー製造に用いられるポリオール、例えば、末端にポリヒドロキシル基を有するポリエーテルポリオール、ポリエステルポリオール及び両者の共重合物であるポリエーテルポリオールが挙げられるほか、ポリブタジエンポリオールやポリイソプレンポリオール等のポリオレフィンポリオール、ポリオール中でエチレン性不飽和単量体を重合させて得られる所謂ポリマーポリオールなどの一般的なポリオールが使用できる。また、イソシアネート成分としては、同様に一般的な軟質ポリウレタンフォームやウレタンエラストマー製造に使用されるポリイソシアネート、即ち、トリレンジイソシアネート（ＴＤＩ）、粗製ＴＤＩ、４，４−ジフェニルメタンジイソシアネート（ＭＤＩ）、粗製ＭＤＩ、炭素数２〜１８の脂肪族ポリイソシアネート、炭素数４〜１５の脂環式ポリイソシアネート及びこれらポリイソシアネートの混合物や変性物、例えば、部分的にポリオール類と反応させて得られるプレポリマー等が用いられる。この場合、ポリオール成分を予めイソシアネート成分によりプレポリマー化しておくこともできる。なお、イソシアネート成分の使用量は常用量でよい。
【００１７】
また、必要に応じて配合される導電性付与材料としては、ケッチェンブラックＥＣ、アセチレンブラック等の導電性カーボン、ＳＡＦ、ＩＳＡＦ、ＨＡＦ、ＦＥＦ、ＧＰＦ、ＳＲＦ、ＦＴ、ＭＴ等のゴム用カーボン、酸化処理等を施したカラー（インク）用カーボン、熱分解カーボン、天然グラファイト、人造グラファイト、アンチモンドープの酸化錫、酸化チタン、酸化亜鉛、ニッケル、銅、銀、ゲルマニウム等の金属及び金属酸化物、ポリアニリン、ポリピロール、ポリアセチレン等の導電性ポリマー等が挙げられる。その配合量は、目的とする導電率により自由に調整できるが、一般的にはポリオール成分とイソシアネート成分の合計量１００重量部に対して３〜１００重量部、特に５〜５０重量部とすることができ、これにより体積固有抵抗を１０^２〜１０^１０Ω・ｃｍに調整することができる。更に、導電性付与材料としては、過塩素酸リチウム等の無機イオン物質や４級アンモニウム塩等の有機イオン物質からなるイオン性導電剤、陽イオン性界面活性剤、負イオン性界面活性剤、各種ベタイン等の両性イオン性界面活性剤、親水性のポリエーテルやポリエステル等の非イオン性帯電防止剤を併用してもよい。その配合量も、目的とする導電率により適宜選定されるが、一般的にはポリオール成分とイソシアネート成分の合計量１００重量部に対して０．５〜５０重量部、特に１〜３０重量部とすることができ、これにより体積固有抵抗を１０^２〜１０^１０Ω・ｃｍに調整することができる。なお、その他の導電性付与材料では、テトラシアノエチレン、テトラシアノキノジメタン、ベンゾキノン、クロルアニル、アントラキノン、アントラセン、ジクロロジシアノベンゾキノン、フェロセン、フタロシアニン等の電荷移動錯体を形成し得る電子受容物質を配合することもでき、その場合の配合量も適宜選定し得るが、一般的にはポリオール成分とイソシアネート成分との合計量１００重量部に対して０．００１〜２０重量部、特に０．０１〜１重量部とすることができる。
【００１８】
本発明において、整泡剤としては、下記一般式で表されるシリコーン整泡剤の１種又は２種以上を使用する。
【００１９】
【化３】

【００２０】
但し、ｍ＝５〜２５、好ましくは１０〜２０であり、ｎ＝０〜１０、好ましくは１〜５である。この場合、ｍ／ｎは１〜１０であることが本発明の目的からより好適である。また、ａ＝２５〜１００、好ましくは３０〜６０であり、ｂ＝５〜４０、好ましくは１０〜２０である。ＥＯ、ＰＯは上記と同様の意味を示す。
【００２１】
上記シリコーン整泡剤の配合量は、ねらいとするセル（気泡）の大きさによって自由に調整できるが、一般的にはポリオール成分とイソシアネート成分との合計量１００重量部に対して０．５〜５重量部であり、これによって十分な効果を得ることができる。
【００２２】
なお、本発明の組成物には、上記シリコーン整泡剤に加えて、他のシリコーン整泡剤、その他各種の整泡剤を本発明の目的を損なわない範囲で配合してもよく、更に触媒、顔料、その他必要に応じて各種粉末や老化防止剤、酸化防止剤等を配合することもできる。
【００２３】
本発明の組成物を用いてウレタンフォームを得る方法としては常法が採用し得、例えばプレポリマーをポリオール架橋反応させる方法、ポリオールをワン・ショット法にてポリイソシアネートと反応させる方法などで得ることができる。この場合、フォーム化に際しては上記組成物を機械撹拌により泡立て、得られた発泡体を成形、硬化する方法を採用する。
【００２４】
このように得られた軟質ポリウレタンフォームは、特に電子写真装置や静電記録装置などで、転写、現像、トナー層形成、クリーニング、給紙、搬送等に用いるローラ、ブレード、ベルトなどの部材の構成材料として有用であり、導電性付与材料を配合して導電性を付与したものは、これら部材の表面導電層の形成などに好適に用いられる。
【００２５】
例えば、金属製の中実体からなる芯金や内部を中空にくりぬいた金属製円筒体等の金属製シャフトなどの良導電性シャフトの外周に導電性を有する弾性層を形成してなる転写ローラにおいて、この弾性層として本発明に係るウレタンフォームが用いられる。
【００２６】
なお、このような弾性層を本発明に係るウレタンフォームにて形成する場合、その硬度は特に制限されないが、ＪＩＳ−Ａスケールで６０°以下、特に１０〜５５°とすることが好ましい。この場合、硬度が６０°を超えると感光ドラム等との接触面積が小さくなり、良好な接触が行えなくなるおそれがある。逆にあまり低硬度にすると、セル（気泡）径が大きくなり、使用目的によっては十分な特性が得られないことがある。
【００２７】
【実施例】
以下、実施例及び比較例を示し、本発明を具体的に説明するが、本発明は下記の実施例に制限されるものではない。
【００２８】
〔実施例１〕
グリセリンにプロピレンオキサイドとエチレンオキサイドを付加して、分子量５，０００としたポリエーテルポリオール（ＯＨ価３３）〔旭硝子（株）製のエクセノール（登録商標）８２８〕１００重量部、ウレタン変性したＭＤＩ（ＮＣＯ％＝２３％）〔住友バイエルウレタン（株）製のスミジュール（登録商標）ＰＦ〕２５．０重量部、１，４−ブタンジオール２．５重量部、表１に示すシリコーン界面活性剤Ａ２．０重量部及びジブチルチンジラウレート０．０１重量部を１リットルのプラスチック容器に入れ、家庭用泡立器で２分間撹拌して微細な均一セルを有する発泡体を得た。この発泡体を２５０ｍｍ（長さ）×３０ｍｍ（巾）×３０ｍｍ（深さ）の型に流し込み、１４０℃で２０分間加熱して硬化させた。
【００２９】
〔実施例２〜５、比較例１〜３〕
シリコーン界面活性剤の種類、配合量を表１，２に示すように代えた以外は実施例１と同様にしてウレタンフォームを得た。
【００３０】
〔実施例６〕
実施例１のポリエーテルポリオールにカーボンブラックＦＴ２０重量部を添加した以外は実施例１と同様にしてウレタンフォームを得た。
【００３１】
次に、上記実施例、比較例で得られたウレタンフォームを用いて下記方法で汚染テストを行った。結果を表２に示す。
〈汚染テスト〉
作製したフォームを１ｃｍ×１ｃｍ×０．５ｍｍに切り出して、市販のレーザービームプリンタの感光体（ＯＰＣ）に１ｋｇ／ｃｍ^３の力で圧接し、５０℃、９０％ＲＨ環境下に１週間放置後、サンプル接触部を観察すると共に、画像出しを行い、画像に不具合（濃度むら等）が発生していないか確認した。
【００３２】
【表１】

【００３３】
【表２】

【００３４】
【発明の効果】
本発明によれば、均一なセル径を有するウレタンフォームが得られ、また相手部材と接触してもこれを汚染することのないものであるので、このフォームは各種弾性部材の製造、特に導電性弾性部材に有効である。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a composition for producing a urethane foam and an elastic material and an elastic member, and in particular, a copying machine, a transfer, an electrophotographic apparatus such as a printer, an electrostatic recording apparatus, and the like, transfer, development, toner layer formation, cleaning, paper feeding, The present invention relates to a urethane foam-producing composition, an elastic material, and an elastic member suitable for producing members such as rollers, blades, and belts for transportation.
[0002]
Problems to be solved by the prior art and the invention
Conventionally, many members have been used in electrophotographic devices such as copiers and printers, electrostatic recording devices, and the like. In an electrophotographic process, transfer, development, formation of a toner layer, cleaning, paper feeding, conveyance, and the like are performed. It fulfills various functions as a member.
[0003]
It is necessary to set the hardness of such members to be low in common, in order to satisfy each role by contacting other members according to each function.
[0004]
For example, a roller used in a transfer device has a function of charging a transfer sheet and transferring toner from the electrostatic latent image visualized by a developer (toner) to the transfer sheet, but a photosensitive drum holding the electrostatic latent image In order to perform the transfer with the roller pressed against the side, a material having a low hardness and conductive material disposed on the outer periphery (elastic layer) is used.
[0005]
In this case, urethane foam is generally widely used as the low hardness material, but has the following disadvantages.
[0006]
That is, as a method for producing a urethane foam, generally, a method of foaming (forming) a raw material composition for producing a urethane foam by the following three methods is adopted.
{Circle around (1)} A foaming agent such as Freon is mixed.
{Circle around (2)} Water is added to the raw material composition, and foaming is caused by carbon dioxide gas generated by the reaction of water and isocyanate simultaneously with the resinification reaction.
{Circle around (3)} The gas is mixed into the raw material composition by mechanical stirring and then cured.
[0007]
In this case, according to the methods (1) and (2), a low-density foam having a relatively large cell size can be easily produced, but it is difficult to produce a foam having a small cell size. In particular, when a conductive foam such as carbon is mixed to form a conductive foam, the viscosity of the raw material becomes extremely high. Therefore, foaming and resinification are simultaneously performed as in methods (1) and (2). As you proceed, it is very difficult to control the bubbles small.
[0008]
For these reasons, urethane foam obtained by mixing and dispersing a gas into a raw material composition by mechanical stirring in (3) and then curing the same is particularly used as a material for a roller used in a copying machine or a printer. It is increasingly used.
[0009]
However, when urethane foam is produced by the method (3), since foaming and resinification are performed separately, it is necessary to stably hold the foam in the foamed raw material composition until resinification proceeds. When the retention of the foam is poor, the foam becomes larger in diameter, the cell becomes rough, and the like due to the merger of the foam before the resin is formed.
[0010]
As a foam stabilizer capable of solving the above problems in the method (3), a high molecular weight linear non-hydrolyzable (AB) _n siloxane-polyoxyalkylene block copolymer as described in U.S. Pat. No. 4,022,722 At present, it is common to use such a foam stabilizer. However, such a foam stabilizer has a very large molecular weight (about 30,000 or more), a high viscosity, and is difficult to handle. Also, since a large amount of the polyoxyalkylene compound is added at the time of synthesis for the purpose of, for example, reducing the viscosity, the polyoxyalkylene compound bleeds after the urethane foam is formed, causing contamination or corrosion of the mating member in contact with the foam. It becomes. Further, since it is a copolymer having a large molecular weight, polysiloxane remains during the synthesis, which also causes contamination and corrosion.
[0011]
The present invention has been made in view of the above circumstances, and it is possible to obtain a urethane foam having a uniform cell diameter, and to obtain a urethane foam that does not contaminate a mating member that comes into contact even when used for a member such as a roller. It is an object of the present invention to provide a composition for producing urethane foam, an elastic material comprising a reaction product of the composition, and an elastic member such as a roller having an elastic layer of the elastic material on the surface.
[0012]
Means for Solving the Problems and Embodiments of the Invention
The present invention, in order to achieve the above object,
(I) Production of polyurethane foam in which a mixture containing a compound having two or more active hydrogens, a compound having two or more isocyanate groups, and a silicone-based foam stabilizer is foamed by mechanical stirring, and the obtained foam is molded and cured. A composition for producing a urethane foam, wherein at least a silicone foam stabilizer represented by the following general formula (1) is used as the foam stabilizer.
(II) The composition according to (1), further comprising a conductivity-imparting material,
(III) An elastic member comprising an elastic material comprising a reaction product of the composition according to (1) or (2), and (IV) an elastic layer of the elastic material according to (3) formed on a surface. I will provide a.
[0013]
Embedded image

(However, m = 5 to 25, n = 0 to 10, a = 25 to 100, b = 5 to 40. EO indicates ethylene oxide, and PO indicates propylene oxide.)
[0014]
That is, the present inventors use the silicone foam stabilizer of the formula (1) as a silicone foam stabilizer, which has a reactive hydroxyl group at its terminal, and thus has two or more active materials, which are main materials. Crosslinking occurs simultaneously during the reaction of a compound having hydrogen (polyol component) and a compound having two or more isocyanate groups (isocyanate component), so that even when used for a member such as a roller, the other member to be contacted is contaminated. The urethane foam having a uniform cell diameter can be obtained without any problems.Furthermore, the foam stabilizer of this structure has not only a moderate surface active effect on the urethane raw material, but also excellent durability of the surface active effect. Therefore, the present inventors have found that a foam obtained by foaming by mechanical stirring can have a low density and a cell having a small range of cell diameters, and have completed the present invention.
[0015]
Hereinafter, the present invention will be described in more detail. The composition for producing a urethane foam of the present invention comprises a compound having two or more active hydrogens (polyol component), a compound having two or more isocyanate groups (isocyanate component), It contains a foaming agent and, if necessary, a conductivity-imparting material.
[0016]
Here, examples of the polyol component include polyols used for production of general flexible polyurethane foams and urethane elastomers, for example, polyether polyols having a polyhydroxyl group at a terminal, polyester polyols, and polyether polyols which are copolymers of both. In addition, general polyols such as polyolefin polyols such as polybutadiene polyol and polyisoprene polyol, and so-called polymer polyols obtained by polymerizing ethylenically unsaturated monomers in a polyol can be used. Examples of the isocyanate component include polyisocyanates which are also used for producing general flexible polyurethane foams and urethane elastomers, that is, tolylene diisocyanate (TDI), crude TDI, 4,4-diphenylmethane diisocyanate (MDI), crude MDI Aliphatic polyisocyanates having 2 to 18 carbon atoms, alicyclic polyisocyanates having 4 to 15 carbon atoms, and mixtures and modified products of these polyisocyanates, such as prepolymers obtained by partially reacting with polyols. Used. In this case, the polyol component may be prepolymerized with an isocyanate component in advance. The amount of the isocyanate component used may be a normal dose.
[0017]
Examples of the conductivity-imparting material to be blended as needed include conductive carbon such as Ketjen Black EC and acetylene black, rubber carbon such as SAF, ISAF, HAF, FEF, GPF, SRF, FT, and MT; Metals and metal oxides such as color (ink) carbon, pyrolytic carbon, natural graphite, artificial graphite, antimony-doped tin oxide, titanium oxide, zinc oxide, nickel, copper, silver, germanium, etc. Examples include conductive polymers such as polyaniline, polypyrrole, and polyacetylene. The compounding amount can be freely adjusted depending on the desired electric conductivity, but is generally 3 to 100 parts by weight, particularly 5 to 50 parts by weight, based on 100 parts by weight of the total of the polyol component and the isocyanate component. This allows the volume resistivity to be adjusted to 10 ² to 10 ¹⁰ Ω · cm. Further, as the conductivity-imparting material, ionic conductive agents composed of inorganic ionic substances such as lithium perchlorate or organic ionic substances such as quaternary ammonium salts, cationic surfactants, anionic surfactants, A zwitterionic surfactant such as betaine and a nonionic antistatic agent such as hydrophilic polyether and polyester may be used in combination. The blending amount is also appropriately selected depending on the intended electrical conductivity, but is generally 0.5 to 50 parts by weight, particularly 1 to 30 parts by weight based on 100 parts by weight of the total amount of the polyol component and the isocyanate component. Thus, the volume resistivity can be adjusted to 10 ² to 10 ¹⁰ Ω · cm. In addition, in other conductivity-imparting materials, an electron accepting substance capable of forming a charge transfer complex such as tetracyanoethylene, tetracyanoquinodimethane, benzoquinone, chloranil, anthraquinone, anthracene, dichlorodicyanobenzoquinone, ferrocene, and phthalocyanine is compounded. In this case, the compounding amount can be appropriately selected, but generally, 0.001 to 20 parts by weight, particularly 0.01 to 1 part by weight based on 100 parts by weight of the total amount of the polyol component and the isocyanate component. Part.
[0018]
In the present invention, as the foam stabilizer, one or more silicone foam stabilizers represented by the following general formula are used.
[0019]
Embedded image

[0020]
However, m = 5 to 25, preferably 10 to 20, and n = 0 to 10, preferably 1 to 5. In this case, it is more preferable that m / n is 1 to 10 for the purpose of the present invention. Also, a = 25 to 100, preferably 30 to 60, and b = 5 to 40, preferably 10 to 20. EO and PO have the same meaning as described above.
[0021]
The blending amount of the silicone foam stabilizer can be freely adjusted depending on the size of the cell (bubbles) to be targeted, but is generally 0.5 to 100 parts by weight based on the total amount of the polyol component and the isocyanate component. 5 parts by weight, whereby a sufficient effect can be obtained.
[0022]
The composition of the present invention may contain, in addition to the above silicone foam stabilizer, other silicone foam stabilizers and other various foam stabilizers as long as the object of the present invention is not impaired. , A pigment, and, if necessary, various powders, an antioxidant, an antioxidant, and the like.
[0023]
As a method for obtaining a urethane foam using the composition of the present invention, a conventional method can be adopted, for example, a method in which a prepolymer is subjected to a polyol crosslinking reaction, a method in which a polyol is reacted with a polyisocyanate by a one-shot method, or the like. Can be. In this case, when forming the foam, a method is employed in which the composition is foamed by mechanical stirring, and the obtained foam is molded and cured.
[0024]
The flexible polyurethane foam obtained in this manner is used for transferring, developing, forming a toner layer, cleaning, feeding, transporting, and other members used in an electrophotographic apparatus or an electrostatic recording apparatus. A material which is useful as a material and has conductivity imparted by blending a conductivity imparting material is suitably used for forming a surface conductive layer of these members.
[0025]
For example, in a transfer roller in which a conductive elastic layer is formed on the outer periphery of a good conductive shaft such as a metal shaft such as a metal core having a solid metal body or a hollow cylindrical metal body. The urethane foam according to the present invention is used as the elastic layer.
[0026]
When such an elastic layer is formed of the urethane foam according to the present invention, its hardness is not particularly limited, but is preferably 60 ° or less, particularly preferably 10 to 55 ° on a JIS-A scale. In this case, if the hardness exceeds 60 °, the contact area with the photosensitive drum or the like becomes small, and good contact may not be performed. Conversely, if the hardness is too low, the cell (bubble) diameter becomes large, and sufficient characteristics may not be obtained depending on the purpose of use.
[0027]
【Example】
Hereinafter, the present invention will be described specifically with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.
[0028]
[Example 1]
100 parts by weight of polyether polyol (OH value 33) [Exenol (registered trademark) 828 manufactured by Asahi Glass Co., Ltd.] having a molecular weight of 5,000 by adding propylene oxide and ethylene oxide to glycerin, and urethane-modified MDI (NCO % = 23%) [Sumidur (registered trademark) PF, manufactured by Sumitomo Bayer Urethane Co., Ltd.] 25.0 parts by weight, 2.5 parts by weight of 1,4-butanediol, silicone surfactant A2 shown in Table 1 0 parts by weight and 0.01 parts by weight of dibutyltin dilaurate were placed in a 1-liter plastic container and stirred with a household whisk for 2 minutes to obtain a foam having fine uniform cells. This foam was poured into a mold of 250 mm (length) × 30 mm (width) × 30 mm (depth) and cured by heating at 140 ° C. for 20 minutes.
[0029]
[Examples 2 to 5, Comparative Examples 1 to 3]
A urethane foam was obtained in the same manner as in Example 1, except that the types and amounts of the silicone surfactant were changed as shown in Tables 1 and 2.
[0030]
[Example 6]
A urethane foam was obtained in the same manner as in Example 1, except that 20 parts by weight of carbon black FT was added to the polyether polyol of Example 1.
[0031]
Next, using the urethane foams obtained in the above Examples and Comparative Examples, a contamination test was performed by the following method. Table 2 shows the results.
<Contamination test>
The prepared foam was cut into 1 cm × 1 cm × 0.5 mm and pressed against a photoreceptor (OPC) of a commercially available laser beam printer with a force of 1 kg / cm ³ , and left for 1 week in a 50 ° C., 90% RH environment. While observing the sample contact portion, an image was taken out, and it was confirmed whether a defect (uneven density or the like) had occurred in the image.
[0032]
[Table 1]

[0033]
[Table 2]

[0034]
【The invention's effect】
According to the present invention, a urethane foam having a uniform cell diameter can be obtained, and it does not contaminate a mating member even when it comes into contact with the mating member. Effective for elastic members.

Claims (4)

For producing polyurethane foam, comprising a mixture containing a compound having two or more active hydrogens, a compound having two or more isocyanate groups and a silicone-based foam stabilizer, foaming by mechanical stirring, and molding and curing the obtained foam. In the composition, at least the following general formula (1) is used as a foam stabilizer.

(However, m = 5 to 25, n = 0 to 10, a = 25 to 100, b = 5 to 40. EO indicates ethylene oxide, and PO indicates propylene oxide.)
A composition for producing a urethane foam, comprising a silicone foam stabilizer represented by the formula: The composition according to claim 1, further comprising a conductivity-imparting material. An elastic material comprising a reaction product of the composition according to claim 1. An elastic member comprising an elastic layer made of the elastic material according to claim 3 formed on a surface thereof.