JP4309635B2 - Lubricating oil composition for internal combustion engines - Google Patents

Description

【００２７】
【化２】

【００２８】
一般式（２）又は（３）において、Ｒ¹⁰、Ｒ¹¹及びＲ¹²は、それぞれ個別にポリブテニル基を示し、ｎは２〜７の整数を示す。本発明においては、本発明の効果をより高めることができる点で、一般式（３）で表わされるビスタイプのコハク酸イミドであることが好ましい。
上記Ｒ¹⁰、Ｒ¹¹及びＲ¹²で表されるポリブテニル基は、その数平均分子量が７００以上であることが好ましく、更に好ましくは９００以上であり、一方、ポリブテニル基の数平均分子量は３５００以下であることが好ましく、更に好ましくは２５００以下、特に好ましくは１５００以下である。数平均分子量を７００以上とすることによって、清浄性、分散性により優れた潤滑油組成物を得ることが可能となる。一方、数平均分子量を３５００以下とすることによって、低温流動性により優れた潤滑油組成物を得ることが可能となる。スラッジ抑制効果に優れる点から、ｎの下限値は２で、好ましくは３であり、一方、ｎの上限値は７で、好ましくは６である。ここで、ポリブテニル基は、１−ブテンとイソブテンの混合物又は高純度イソブテンを塩化アルミニウム、フッ化ホウ素等の触媒で重合して得られるポリブテン（ポリイソブテン）から得ることができ、ポリブテン混合物中において末端にビニリデン構造を有するものが通常５〜１００モル％含有される。また、このポリブテン（ポリイソブテン）としては、製造過程の触媒に起因し、残留する微量のフッ素分や塩素分を更に適当な処理法により除去されたものも使用することができ、従ってこれらのフッ素や塩素等のハロゲン元素の含有量は５０質量ｐｐｍ以下であることが好ましく、より好ましくは１０質量ｐｐｍ以下、更に好ましくは５質量ｐｐｍ以下、特に好ましくは１質量ｐｐｍ以下であるものも使用できる。
【００２９】
一般式（２）又は（３）で表されるコハク酸イミドの製造法は特に制限はない。例えば、上記ポリブテンを塩素化したもの、好ましくは塩素やフッ素が充分除去されたポリブテンを無水マレイン酸と１００〜２００℃で反応させて得られるポリブテニルコハク酸を、ジエチレントリアミン、トリエチレンテトラミン、テトラエチレンペンタミン、あるいはペンタエチレンヘキサミン等のポリアミンと反応させる方法を利用することができる。なお、ビスコハク酸イミドを製造する場合は、該ポリブテニルコハク酸をポリアミンの２倍量（モル比）反応させれば良く、モノコハク酸イミドを製造する場合は、該ポリブテニルコハク酸とポリアミンを等量（モル比）で反応させれば良い。
【００３０】
また、コハク酸イミドの誘導体としては、例えば、一般式（２）又は（３）で表される化合物に含酸素有機化合物やホウ素化合物等を作用させて残存するアミノ基及び／又はイミノ基の一部又は全部を中和したり、アミド化した化合物であってもよい。
含酸素有機化合物としては、具体的には、例えば、ぎ酸、酢酸、グリコール酸、プロピオン酸、乳酸、酪酸、吉草酸、カプロン酸、エナント酸、カプリル酸、ペラルゴン酸、カプリン酸、ウンデシル酸、ラウリン酸、トリデカン酸、ミリスチン酸、ペンタデカン酸、パルミチン酸、マルガリン酸、ステアリン酸、オレイン酸、ノナデカン酸、エイコサン酸等の炭素数１〜３０のモノカルボン酸；シュウ酸、フタル酸、トリメリット酸、ピロメリット酸等の炭素数２〜３０のポリカルボン酸若しくはこれらの無水物、又はエステル化合物；炭素数２〜６のアルキレンオキサイド；ヒドロキシ（ポリ）オキシアルキレンカーボネート等が挙げられる。このような含酸素有機化合物を作用させることで、例えば、一般式（２）又は（３）の化合物におけるアミノ基又はイミノ基の一部又は全部が下記の一般式（４）で示す構造になると推定される。
【００３１】
【化３】

【００３２】
ここでＲ¹³は水素原子、炭素数１〜２４のアルキル基、アルケニル基、アルコキシ基、又は−Ｏ−(Ｒ¹⁴Ｏ)_mＨで表されるヒドロキシ（ポリ）オキシアルキレン基を示し、Ｒ¹⁴は炭素数１〜４のアルキレン基を示し、ｍは１〜５の整数を示す。
【００３３】
ホウ素化合物としては、ホウ酸、ホウ酸塩、ホウ酸エステル類等が挙げられる。ホウ酸としては、具体的には例えばオルトホウ酸、メタホウ酸及びテトラホウ酸等が挙げられる。ホウ酸塩としては、ホウ酸のアルカリ金属塩、アルカリ土類金属塩又はアンモニウム塩等が挙げられ、より具体的には、例えばメタホウ酸リチウム、四ホウ酸リチウム、五ホウ酸リチウム、過ホウ酸リチウム等のホウ酸リチウム；メタホウ酸ナトリウム、二ホウ酸ナトリウム、四ホウ酸ナトリウム、五ホウ酸ナトリウム、六ホウ酸ナトリウム、八ホウ酸ナトリウム等のホウ酸ナトリウム；メタホウ酸カリウム、四ホウ酸カリウム、五ホウ酸カリウム、六ホウ酸カリウム、八ホウ酸カリウム等のホウ酸カリウム；メタホウ酸カルシウム、二ホウ酸カルシウム、四ホウ酸三カルシウム、四ホウ酸五カルシウム、六ホウ酸カルシウム等のホウ酸カルシウム；メタホウ酸マグネシウム、二ホウ酸マグネシウム、四ホウ酸三マグネシウム、四ホウ酸五マグネシウム、六ホウ酸マグネシウム等のホウ酸マグネシウム；及びメタホウ酸アンモニウム、四ホウ酸アンモニウム、五ホウ酸アンモニウム、八ホウ酸アンモニウム等のホウ酸アンモニウム等が挙げられる。また、ホウ酸エステルとしては、ホウ酸と好ましくは炭素数１〜６の脂肪族アルコールとのエステル等が挙げられ、より具体的には例えば、ホウ酸モノメチル、ホウ酸ジメチル、ホウ酸トリメチル、ホウ酸モノエチル、ホウ酸ジエチル、ホウ酸トリエチル、ホウ酸モノプロピル、ホウ酸ジプロピル、ホウ酸トリプロピル、ホウ酸モノブチル、ホウ酸ジブチル、及びホウ酸トリブチル等が挙げられる。
【００３４】
ホウ素化合物を作用させたコハク酸イミドは、そのホウ素量と窒素量の質量比(Ｂ／Ｎ比）に特に制限はないが、塩基価維持性及び高温清浄性を高める観点から０．１〜１．２であることが好ましく、０．２〜１．０であることがさらに好ましく、０．３〜０．９であることが特に好ましい。
【００３５】
本発明においては、（Ｂ）成分として、上記コハク酸イミド及びその誘導体の中から選ばれる１種又は２種以上を使用することができる。
【００３６】
本発明における（Ｂ）成分の含有量の下限値は、組成物全量基準で、窒素元素換算量で、０．０１質量％であり、０．０５質量％であることが好ましく、０．０８質量％であることが特に好ましい。一方、その上限値は、組成物全量基準で、窒素元素換算量で、０．３質量％であり、０．２質量％であることが好ましく、０．１５質量％であることが特に好ましい。（Ｂ）成分の含有量が０．０１質量％未満である場合、本発明の効果が得られず、またその含有量が０．３質量％を超える場合、組成物の低温粘度特性及び抗乳化性が悪化するためそれぞれ好ましくない。
【００３７】
本発明における（Ｃ）成分は、アルカリ金属又はアルカリ土類金属系清浄剤である。この（Ｃ）成分には、アルカリ金属又はアルカリ土類金属スルホネート、アルカリ金属又はアルカリ土類金属フェネート、及びアルカリ金属又はアルカリ土類金属サリシレート等が含まれる。本発明では、これらからなる群より選ばれる１種又は２種以上のアルカリ金属又はアルカリ土類金属系清浄剤、特にアルカリ土類金属系清浄剤を好ましく使用することができる。
【００３８】
アルカリ土類金属スルホネートとしては、分子量３００〜１５００、好ましくは４００〜７００のアルキル芳香族化合物をスルホン化することによって得られるアルキル芳香族スルホン酸のアルカリ土類金属塩、特にマグネシウム塩及び／又はカルシウム塩であり、カルシウム塩が好ましく用いられる。
上記アルキル芳香族スルホン酸としては、具体的にはいわゆる石油スルホン酸や合成スルホン酸等が挙げられる。
上記石油スルホン酸としては、一般に鉱油の潤滑油留分のアルキル芳香族化合物をスルホン化したものやホワイトオイル製造時に副生する、いわゆるマホガニー酸等が用いられる。また合成スルホン酸としては、例えば洗剤の原料となるアルキルベンゼン製造プラントから副生したり、炭素数２〜１２のオレフィン（エチレン、プロピレン等）のオリゴマーをベンゼンにアルキル化することにより得られる、直鎖状や分枝状のアルキル基を有するアルキルベンゼンをスルホン化したもの、あるいはジノニルナフタレン等のアルキルナフタレンをスルホン化したもの等が用いられる。またこれらアルキル芳香族化合物をスルホン化する際のスルホン化剤としては特に制限はないが、通常発煙硫酸や無水硫酸が用いられる。
【００３９】
アルカリ土類金属フェネートとしては、例えば、アルキルフェノール、アルキルフェノールサルファイド、アルキルフェノールのマンニッヒ反応物のアルカリ土類金属塩、特にマグネシウム塩及びカルシウム塩が挙げられる。具体的には、下記一般式（５）、（６）及び（７）で表されるものを挙げることができる。
【００４０】
【化４】

【００４１】
【化５】

【００４２】
【化６】

【００４３】
上記一般式（５）、（６）、及び（７）において、Ｒ²¹、Ｒ²²、Ｒ²³、Ｒ²⁴、Ｒ²⁵及びＲ²⁶はそれぞれ同一でも異なっていてもよく、それぞれ炭素数４〜３０、好ましくは６〜１８の直鎖又は分枝のアルキル基を示し、Ｍ¹、Ｍ²及びＭ³は、それぞれアルカリ土類金属、好ましくはカルシウム又はマグネシウムを示し、ｘは１または２を示す。
【００４４】
上記Ｒ²¹、Ｒ²²、Ｒ²³、Ｒ²⁴、Ｒ²⁵及びＲ²⁶で表されるアルキル基としては、具体的には、それぞれ個別に、ブチル基、ペンチル基、ヘキシル基、ヘプチル基、オクチル基、ノニル基、デシル基、ウンデシル基、ドデシル基、トリデシル基、テトラデシル基、ペンタデシル基、ヘキサデシル基、ヘプタデシル基、オクタデシル基、ノナデシル基、イコシル基、ヘンイコシル基、ドコシル基、トリコシル基、テトラコシル基、ペンタコシル基、ヘキサコシル基、ヘプタコシル基、オクタコシル基、ノナコシル基、及びトリアコンチル基等が挙げられる。これらは直鎖でも分枝でもよい。これらはまた１級アルキル基、２級アルキル基又は３級アルキル基でもよい。
【００４５】
アルカリ土類金属サリシレートとしては、例えば、アリキルサリチル酸のアルカリ土類金属塩、特にマグネシウム塩及びカルシウム塩が挙げられる。具体的には下記一般式（８）で表される化合物を挙げることができる。
【００４６】
【化７】

【００４７】
一般式（８）において、Ｒ²⁷は炭素数４〜３０、好ましくは６〜１８の直鎖又は分枝のアルキル基を示し、Ｍ⁴はアルカリ土類金属、好ましくはカルシウム又はマグネシウムを示す。
上記Ｒ²⁷で表されるアルキル基としては、具体的には、ブチル基、ペンチル基、ヘキシル基、ヘプチル基、オクチル基、ノニル基、デシル基、ウンデシル基、ドデシル基、トリデシル基、テトラデシル基、ペンタデシル基、ヘキサデシル基、ヘプタデシル基、オクタデシル基、ノナデシル基、イコシル基、ヘンイコシル基、ドコシル基、トリコシル基、テトラコシル基、ペンタコシル基、ヘキサコシル基、ヘプタコシル基、オクタコシル基、ノナコシル基、トリアコンチル基等が挙げられ、これらは直鎖でも分枝でもよい。これらはまた１級アルキル基、２級アルキル基又は３級アルキル基でもよい。
【００４８】
アルカリ土類金属スルホネート、アルカリ土類金属フェネート及びアルカリ土類金属サリシレートには、上記のアルキル芳香族スルホン酸、アルキルフェノール、アルキルフェノールサルファイド、アルキルフェノールのマンニッヒ反応物、アルキルサリチル酸等を直接、マグネシウム及び／又はカルシウムのアルカリ土類金属の酸化物や水酸化物等のアルカリ土類金属塩基と反応させたり、又は一度ナトリウム塩やカリウム塩等のアルカリ金属塩としてからアルカリ土類金属塩と置換させること等により得られる中性（正塩）アルカリ土類金属スルホネート、中性（正塩）アルカリ土類金属フェネート及び中性（正塩）アルカリ土類金属サリシレート；あるいは中性アルカリ土類金属スルホネート、中性アルカリ土類金属フェネート及び中性アルカリ土類金属サリシレートと過剰のアルカリ土類金属塩やアルカリ土類金属塩基を水の存在下で加熱することにより得られる塩基性アルカリ土類金属スルホネート、塩基性アルカリ土類金属フェネート及び塩基性アルカリ土類金属サリシレート；更には中性アルカリ土類金属スルホネート、中性アルカリ土類金属フェネート及び中性アルカリ土類金属サリシレートの存在下で、アルカリ土類金属の水酸化物と炭酸ガス又はホウ酸とを反応させることにより得られる過塩基性（超塩基性）アルカリ土類金属スルホネート、過塩基性（超塩基性）アルカリ土類金属フェネート及び過塩基性（超塩基性）アルカリ土類金属サリシレートも含まれる。
【００４９】
本発明においては、上記の中性アルカリ土類金属塩、塩基性アルカリ土類金属塩、過塩基性（超塩基性）アルカリ土類金属塩及びこれらの混合物等を用いることができ、その全塩基価は任意であるが、通常全塩基価が５００ｍｇＫＯＨ／ｇ以下、好ましくは６０〜４００ｍｇＫＯＨ／ｇである。なお、ここで全塩基価は、ＪＩＳ Ｋ２５０１（１９９２）の「石油製品及び潤滑油−中和価試験方法」の７．に準拠して測定される過塩素酸法による全塩基価を意味する。
アルカリ土類金属系清浄剤は、通常、軽質潤滑油基油等で希釈された状態で市販されており、また入手可能であるが、一般的にその金属含有量が１．０〜２０質量％、好ましくは２．０〜１６質量％のものを用いる。
【００５０】
本発明に用いる（Ｃ）成分の金属比としては、特に制限はないが、通常、１〜２０、好ましくは１〜１５のものを用いる。
本発明においては、（Ｃ）成分として、アルカリ金属又はアルカリ土類金属サリシレート系清浄剤を必須として含有することが好ましい。また、その金属比は好ましくは３以下、より好ましくは２．６以下であり、さらに好ましくは２以下、特に好ましくは１．５以下とすることが望ましい。なお、このようなアルカリ金属又はアルカリ土類金属サリシレート系清浄剤は、単独でも、また異なった金属比のものを混合して使用しても良い。例えば、金属比が２以下、好ましくは１．５以下、特に１．２以下であるアルカリ金属又はアルカリ土類金属サリシレートを必須成分として単独で使用したり、金属比が１．５以下、好ましくは１．２以下のものと、金属比が１．５を超えるもの、特に２．６を超えるものとを併用し、アルカリ金属又はアルカリ土類金属サリシレート混合物における金属比が１．３以上、好ましくは２．３以下、より好ましくは２以下、特に好ましくは１．５以下に調製して使用しても良い。アルカリ金属又はアルカリ土類金属サリシレートの金属比を１．３〜２．３の範囲に調製することにより、（Ｃ）成分の含有量に対する塩基価維持性、高温清浄性、さらには低摩擦性の向上効果をより高めることができる。
【００５１】
また、（Ｃ）成分は、金属比が１．５以下、好ましくは１．２以下であるアルカリ金属又はアルカリ土類金属サリシレート系清浄剤と、アルカリ金属又はアルカリ土類金属スルホネート系清浄剤とを併用することが好ましい。なお、アルカリ金属又はアルカリ土類金属スルホネート系清浄剤の金属比は特に制限はないが、通常１〜２０であり、好ましくは１〜１５、特に好ましくは５〜１２である。（Ｃ）成分をこのような構成とすることで、塩基価維持性、高温清浄性、さらには低摩擦性の向上効果をより高めることができる。
【００５２】
なお、ここでいう金属比とは、金属元素の価数×金属元素含有量（ｍｏｌ）／せっけん基（即ち、アルキルサリチル酸基などの基）含有量（ｍｏｌ）で表され、即ち、金属比はアルカリ金属又はアルカリ土類金属系清浄剤中のアルキルサリチル酸基、アルキルスルホン酸基含有量に対するアルカリ金属又はアルカリ土類金属含有量を示す。
【００５３】
本発明におけるアルカリ金属又はアルカリ土類金属系清浄剤（Ｃ）の含有量の下限値は、組成物全量基準で、アルカリ金属又はアルカリ土類金属元素換算量で、０．０５質量％であり、好ましくは０．１質量％、さらに好ましくは０．１５質量％、特に好ましくは０．２質量％である。一方その上限値は、組成物全量基準で、アルカリ金属又はアルカリ土類金属元素換算量で、１質量％であり、好ましくは０．５質量％、さらに好ましくは０．４質量％である。（Ｃ）成分の含有量が０．０５質量％未満の場合、本発明のような優れた塩基価維持性及び高温清浄性を発揮できず、一方（Ｃ）成分の含有量が１質量％を超える場合、含有量に見合うだけの効果が得られないため、それぞれ好ましくない。
【００５４】
本発明の内燃機関用潤滑油組成物における（Ｄ）成分は、フェノール系酸化防止剤及び／又はアミン系酸化防止剤である。
フェノール系酸化防止剤としては、例えば、４，４’−メチレンビス（２，６−ジ−ｔｅｒｔ−ブチルフェノール）、４，４’−ビス（２，６−ジ−ｔｅｒｔ−ブチルフェノール）、４，４’−ビス（２−メチル−６−ｔｅｒｔ−ブチルフェノール）、２，２’−メチレンビス（４−エチル−６−ｔｅｒｔ−ブチルフェノール）、２，２’−メチレンビス（４−メチル−６−ｔｅｒｔ−ブチルフェノール）、４，４’−ブチリデンビス（３−メチル−６−ｔｅｒｔ−ブチルフェノール）、４，４’−イソプロピリデンビス（２，６−ジ−ｔｅｒｔ−ブチルフェノール）、２，２’−メチレンビス（４−メチル−６−ノニルフェノール）、２，２’−イソブチリデンビス（４，６−ジメチルフェノール）、２，２’−メチレンビス（４−メチル−６−シクロヘキシルフェノール）、２，６−ジ−ｔｅｒｔ−ブチル−４−メチルフェノール、２，６−ジ−ｔｅｒｔ−ブチル−４−エチルフェノール、２，４−ジメチル−６−ｔｅｒｔ−ブチルフェノール、２，６−ジ−ｔｅｒｔ−α−ジメチルアミノ−ｐ−クレゾール、２，６−ジ−ｔｅｒｔ−ブチル−４（Ｎ，Ｎ’−ジメチルアミノメチルフェノール）、４，４’−チオビス（２−メチル−６−ｔｅｒｔ−ブチルフェノール）、４，４’−チオビス（３−メチル−６−ｔｅｒｔ−ブチルフェノール）、２，２’−チオビス（４−メチル−６−ｔｅｒｔ−ブチルフェノール）、ビス（３−メチル−４−ヒドロキシ−５−ｔｅｒｔ−ブチルベンジル）スルフィド、ビス（３，５−ジ−ｔｅｒｔ−ブチル−４−ヒドロキシベンジル）スルフィド、２，２’−チオ−ジエチレンビス［３−（３，５−ジ−ｔｅｒｔ−ブチル−４−ヒドロキシフェニル）プロピオネート］、トリデシル−３−（３，５−ジ−ｔｅｒｔ−ブチル−４−ヒドロキシフェニル）プロピオネート、ペンタエリスリチル−テトラキス［３−（３，５−ジ−ｔｅｒｔ−ブチル−４−ヒドロキシフェニル）プロピオネート］、オクタデシル−３−（３，５−ジ−ｔｅｒｔ−ブチル−４−ヒドロキシフェニル）プロピオネート、オクチル−３−（３，５−ジ−ｔｅｒｔ−ブチル−４−ヒドロキシフェニル）プロピオネート、オクチル−３−（３−メチル−５−ｔｅｒｔ−ブチル−４−ヒドロキシフェニル）プロピオネート等が好ましい具体例として挙げられる。これらは二種以上を混合して使用してもよい。
【００５５】
アミン系酸化防止剤としては、例えば、フェニル−α−ナフチルアミン、アルキルフェニル−α−ナフチルアミン、ジアルキルジフェニルアミンを挙げることができる。これらは二種以上を混合して使用してもよい。なお、ここでいうアルキル基は一般に炭素数１〜１６のアルキル基を示す。
上記フェノール系酸化防止剤とアミン系酸化防止剤は単独で使用しても良いが、本発明の効果をより高めることができることから、組み合せて配合することが好ましい。
【００５６】
本発明の潤滑油組成物において（Ｄ）成分の含有量の下限値は、塩基価維持性及び高温清浄性をより高めるために組成物全量基準で０．０１質量％であり、好ましくは０．１質量％、更に好ましくは０．５質量％、特に好ましくは１．０質量％である。一方、（Ｄ）成分の含有量の上限値は、組成物全量基準で３．０質量％であり、好ましくは２．５質量％であり、３．０質量％を超える場合は、配合量に見合った十分な酸化防止性が得られないため好ましくない。
【００５７】
本発明の内燃機関用潤滑油組成物には（Ａ）成分以外の摩耗防止剤を配合することができる。
（Ａ）成分以外の摩耗防止剤としては、下記一般式（９）で表されるチオリン酸エステル若しくはリン酸エステルの金属塩、下記一般式（１０）で表されるチオリン酸エステル若しくはリン酸エステル、又はその金属塩又はアミン塩の他、亜リン酸エステル若しくはチオ亜リン酸エステル、又はその金属塩又はアミン塩、チオリン酸トリエステルやジアルキルジチオリン酸亜鉛、ジアルキルジチオカルバミン酸亜鉛、ジアルキルジチオリン酸モリブデン、ジアルキルジチオカルバミン酸モリブデン、ジスルフィド、硫化オレフィン、硫化油脂等のリン及び／又は硫黄含有摩耗防止剤等が挙げられる。
【００５８】
【化８】

【００５９】
【化９】

【００６０】
上記Ｒ³⁰、Ｒ³¹、Ｒ³²、Ｒ³³、Ｒ³⁴及びＲ³⁵はそれぞれ個別に水素原子又は炭素数１〜３０の炭化水素基を示し、炭素数１〜３０の炭化水素基としては、前記（Ａ）成分の一般式（１）におけるＲ¹と同義であり、またその好ましい範囲も同義である。
【００６１】
上記Ｘ¹、Ｘ²、Ｘ³、Ｘ⁴、Ｘ⁵及びＸ⁶はそれぞれ個別に酸素原子又は硫黄原子を示し、これらのうち少なくとも１つが酸素原子であり、２つ以上が酸素原子であることが好ましく、全てが酸素原子である場合が特に好ましい。少なくとも一つの酸素原子を含むことにより、組成物中の硫黄分をより低減でき、また、酸化又は熱分解を受けた際に硫酸の発生量を低減でき、従って塩基価の消耗を著しく抑制することができる。
【００６２】
Ｙで表される金属原子としては、具体的には、亜鉛、銅、鉄、鉛、ニッケル、銀、マンガン等が挙げられる。より高い摩耗防止性能を得られる点から、Ｙは亜鉛であることが好ましい。
Ｕは、水素（プロトン）、一価の金属イオン又はアンモニウムイオンを示し、ｋは１〜２０の整数であり、Ｕのイオンの数を示す。ｋは１〜１０の整数であることが好ましい。より好ましくは１〜８の整数である。
Ｕで表される一価の金属イオンとしては、塩を形成できる金属原子であり、例えば、リチウム、ナトリウム、カリウム、セシウムなどのアルカリ金属を挙げることができる。アンモニウムイオンは、このイオン由来の化合物、例えば、アミン塩を形成できる含窒素化合物を挙げることができる。
【００６３】
含窒素化合物としては、例えば、アンモニア、モノアミン、ジアミン、ポリアミンが挙げられる。より具体的には、メチルアミン、エチルアミン、プロピルアミン、ブチルアミン、ペンチルアミン、ヘキシルアミン、ヘプチルアミン、オクチルアミン、ノニルアミン、デシルアミン、ウンデシルアミン、ドデシルアミン、トリデシルアミン、テトラデシルアミン、ペンタデシルアミン、ヘキサデシルアミン、ヘプタデシルアミン、オクタデシルアミン、ジメチルアミン、ジエチルアミン、ジプロピルアミン、ジブチルアミン、ジペンチルアミン、ジヘキシルアミン、ジヘプチルアミン、ジオクチルアミン、ジノニルアミン、ジデシルアミン、ジウンデシルアミン、ジドデシルアミン、ジトリデシルアミン、ジテトラデシルアミン、ジペンタデシルアミン、ジヘキサデシルアミン、ジヘプタデシルアミン、ジオクタデシルアミン、メチルエチルアミン、メチルプロピルアミン、メチルブチルアミン、エチルプロピルアミン、エチルブチルアミン、プロピルブチルアミン等の炭素数１〜３０のアルキル基（これらのアルキル基は直鎖状でも分枝状でもよい）を有するアルキルアミン；
【００６４】
エテニルアミン、プロペニルアミン、ブテニルアミン、オクテニルアミン、オレイルアミン等の炭素数２〜３０のアルケニル基（これらのアルケニル基は直鎖状でも分枝状でもよい）を有するアルケニルアミン；メタノールアミン、エタノールアミン、プロパノールアミン、ブタノールアミン、ペンタノールアミン、ヘキサノールアミン、ヘプタノールアミン、オクタノールアミン、ノナノールアミン、メタノールエタノールアミン、メタノールプロパノールアミン、メタノールブタノールアミン、エタノールプロパノールアミン、エタノールブタノールアミン、プロパノールブタノールアミン等の炭素数１〜３０のアルカノール基（これらのアルカノール基は直鎖状でも分枝状でもよい）を有するアルカノールアミン；
【００６５】
メチレンジアミン、エチレンジアミン、プロピレンジアミン、ブチレンジアミン等の炭素数１〜３０のアルキレン基を有するアルキレンジアミン；ジエチレントリアミン、トリエチレンテトラミン、テトラエチレンペンタミン、ペンタエチレンヘキサミン等のポリアミン；ウンデシルジエチルアミン、ウンデシルジエタノールアミン、ドデシルジプロパノールアミン、オレイルジエタノールアミン、オレイルプロピレンジアミン、ステアリルテトラエチレンペンタミン等の上記モノアミン、ジアミン、ポリアミンに炭素数８〜２０のアルキル基又はアルケニル基を有する化合物やＮ−ヒドロキシエチルオレイルイミダゾリン等の複素環化合物；これらの化合物のアルキレンオキシド付加物；及びこれらの混合物等が例示できる。
【００６６】
なお、本発明の内燃機関用潤滑油組成物においては、上記（Ａ）成分以外の摩耗防止剤のうち、硫黄を含有する摩耗防止剤を含有させる場合、その含有量は特に制限はないが、組成物全量基準で、硫黄元素換算量で、０．１質量％以下とすることが好ましく、０．０９質量％以下とすることがさらに好ましい。また、硫黄含有摩耗防止剤を含有させないことが特に好ましい。硫黄含有摩耗防止剤を０．１質量％以下とすることで極めて塩基価維持性、高温清浄性に優れる組成物を得ることが可能となる。
また、上記（Ａ）成分以外の摩耗防止剤のうち、硫黄を含有しないリン含有摩耗防止剤を含有させる場合、通常、その含有量は、組成物全量基準で、リン元素換算量で、０．０１〜０．２質量％である。その場合でも、排ガス浄化触媒等への悪影響が懸念されることから、組成物におけるリン元素換算量が（Ａ）成分と併せて０．２質量％を超えないことが好ましく、０．１５質量％を超えないことが特に好ましい。
【００６７】
本発明の内燃機関用潤滑油組成物は、摩耗防止性、塩基価維持性及び高温清浄性に優れるものであるが、その性能をさらに向上させるために、その目的に応じて任意の添加剤を添加することができる。このような添加剤としては、例えば、粘度指数向上剤、（Ｂ）成分以外の無灰分散剤、（Ｃ）成分以外の金属系清浄剤、摩擦調整剤、腐食防止剤、防錆剤、抗乳化剤、金属不活性化剤、消泡剤、及び着色剤等を挙げることができる。
【００６８】
粘度指数向上剤としては、具体的には、各種メタクリル酸エステルから選ばれる１種又は２種以上のモノマーの共重合体若しくはその水添物などのいわゆる非分散型粘度指数向上剤、又はさらに窒素化合物を含む各種メタクリル酸エステルを共重合させたいわゆる分散型粘度指数向上剤、非分散型又は分散型エチレン−α‐オレフィン共重合体（α‐オレフィンとしてはプロピレン、１‐ブテン、１‐ペンテン等が例示できる）若しくはその水素化物、ポリイソブチレン若しくはその水添物、スチレン−ジエン水素化共重合体、スチレン−無水マレイン酸エステル共重合体及びポリアルキルスチレン等が挙げられる。
これらの粘度指数向上剤の分子量は、せん断安定性を考慮して選定することが好ましい。具体的には、粘度指数向上剤の数平均分子量は、例えば分散型及び非分散型ポリメタクリレートの場合では、５，０００〜１，０００，０００、好ましくは１０，０００〜３５０，０００のものが、ポリイソブチレン又はその水素化物の場合は８００〜５，０００、好ましくは１，０００〜４，０００のものが、エチレン−α−オレフィン共重合体又はその水素化物の場合は８００〜５００，０００、好ましくは３，０００〜２００，０００のものが望ましい。
またこれらの粘度指数向上剤の中でもエチレン−α−オレフィン共重合体又はその水素化物を用いた場合には、特にせん断安定性に優れた潤滑油組成物を得ることができる。上記粘度指数向上剤の中から任意に選ばれた１種類あるいは２種類以上の化合物を任意の量で含有させることができる。粘度指数向上剤の含有量は、通常潤滑油組成物全量基準で０．１〜２０．０質量％である。
【００６９】
（Ｂ）成分以外の無灰分散剤としては、炭素数４０〜４００のアルキル基又はアルケニル基を分子中に少なくとも1個を有するベンジルアミン、ポリアミン及びこれらの誘導体が例示できる。
【００７０】
摩擦調整剤としては、炭素数６〜３０のアルキル基又はアルケニル基を有する脂肪族アミン、脂肪酸、脂肪酸エステル、脂肪族アルコール等が挙げられる。
【００７１】
腐食防止剤としては、例えば、ベンゾトリアゾール系、トリルトリアゾール系、チアゾール系、チアジアゾール系、及びイミダゾール系化合物等が挙げられる。
【００７２】
防錆剤としては、例えば、石油スルホネート、アルキルベンゼンスルホネート、ジノニルナフタレンスルホネート、アルケニルコハク酸エステル、及び多価アルコールエステル等が挙げられる。
【００７３】
抗乳化剤としては、例えば、ポリオキシエチレンアルキルエーテル、ポリオキシエチレンアルキルフェニルエーテル、及びポリオキシエチレンアルキルナフチルエーテル等のポリアルキレングリコール系非イオン系界面活性剤等が挙げられる。
【００７４】
金属不活性化剤としては、例えば、イミダゾリン、ピリミジン誘導体、アルキルチアジアゾール、メルカプトベンゾチアゾール、ベンゾトリアゾール又はその誘導体、１，３，４−チアジアゾールポリスルフィド、１，３，４−チアジアゾリル−２，５−ビスジアルキルジチオカーバメート、２−（アルキルジチオ）ベンゾイミダゾール、及びβ−（ｏ−カルボキシベンジルチオ）プロピオンニトリル等が挙げられる。
【００７５】
消泡剤としては、例えば、シリコーン、フルオロシリコーン、及びフルオロアルキルエーテル等が挙げられる。
【００７６】
これらの添加剤を本発明の潤滑油組成物に含有させる場合には、その含有量は潤滑油組成物全量基準で、（Ｂ）成分以外の無灰分散剤、（Ｃ）成分以外の金属系清浄剤、（Ｄ）成分以外の酸化防止剤、摩擦調整剤、腐食防止剤、防錆剤、抗乳化剤ではそれぞれ０．０１〜５質量％、金属不活性化剤では０．００５〜１質量％、消泡剤では０．０００５〜１質量％の範囲で通常選ばれる。
【００７７】
本発明の内燃機関用潤滑油組成物は、上述の硫黄含有摩耗防止剤と共に、硫黄を含有する添加剤の含有量も制限することが好ましく、硫黄含有添加剤物（硫黄含有摩耗防止剤を含む）の含有量は、組成物全量基準で、硫黄元素換算量で、０．１質量％以下とすることが好ましく、０．０９質量％以下とすることがさらに好ましく、硫黄含有添加剤（硫黄含有摩耗防止剤を含む）を含有させないことが特に好ましい。なお、市販添加剤には、添加剤を合成する際に使用する溶剤や添加剤のハンドリングを良くするための希釈油（例えば溶剤精製鉱油等）を含有している場合が一般的であり、ここでいう硫黄含有添加剤はこれら溶剤や希釈油に起因する硫黄化合物を意味するものではない。
【００７８】
本発明においては、これら溶剤や希釈油に起因する硫黄分が含有されたとしても、組成物中の全硫黄分含有量は、０．２質量％以下、好ましくは０．１５質量％以下、特に好ましくは０．１質量％以下とする。これにより、摩耗防止性、塩基価維持性及び高温清浄性に優れ、さらには排ガス浄化触媒等の性能を維持した組成物が得られる。なお、本発明においては、これら溶剤や希釈油を硫黄分含量が１０質量ｐｐｍ以下である高度水素化分解基油、あるいは実質的に硫黄分を含有しないＧＴＬ Ｗａｘ（ガス・トゥー・リキッド・ワックス）を異性化した手法で製造された基油等、あるいは合成油等を使用し、硫黄含有添加剤を含有させないことで、組成物中の全硫黄分が１０質量ｐｐｍ以下である組成物、あるいは実質的に含有しない組成物を得ることも可能となる。
【００７９】
【実施例】
以下に本発明を実施例及び比較例によってさらに具体的に説明するが、本発明はこれらの例になんら限定されるものではない。
（実施例１〜４及び比較例１、２）
表１に示す組成及び性状の各内燃機関用潤滑油組成物（実施例１〜４及び比較例１、２）をそれぞれ調製した。なお、組成物中の硫黄分が０．０５質量％となっているものは、添加剤の希釈油に起因するものである。
【００８０】
【表１】

【００８１】
上記実施例１〜４及び比較例１、２で得られた内燃機関用潤滑油組成物の性能を下記の性能評価試験により評価した。
（１）ＩＳＯＴによる全塩基価の経時変化
ＪＩＳ Ｋ ２５１４に準拠するＩＳＯＴ試験（１６５．５℃）にて試験油を強制劣化させたときの全塩基価（塩酸法）の経時変化を測定した。その評価結果を表１に示す。全塩基価残存率が高いほど塩基価維持性能が高く、より長時間使用できるロングドレイン油であることを示す。
表１に示すように、本発明の組成物（実施例１〜４）は、ＺＤＴＰ（硫黄含有摩耗防止剤）が内燃機関用潤滑油として一般的な量（硫黄元素量で、０．１６質量％、リン元素量で０．０８質量％）含有する組成物（比較例１及び２）に比べ塩基価維持性が極めて高いことがわかる。中でもトリオクチルホスフェート含有組成物（実施例１）に比べ、トリフェニルホスフェート含有組成物（実施例４）や、特にトリブチルホスフェート含有組成物（実施例３）は塩基価維持性が極めて高いことがわかる。
【００８２】
（２）ＮＯｘ吸収試験による全塩基価の経時変化
日本トライボロジー会議予稿集１９９２、１０、４６５に準拠した条件（１５０℃、ＮＯｘ：１１８５ｐｐｍ）にて試験油にＮＯｘガスを吹き込み、強制劣化させたときの全塩基価（塩酸法）の経時変化を測定した。その評価結果を表１に示す。全塩基価の減少が小さいほど内燃機関で使用されるようなＮＯｘ存在下においても塩基価維持性能が高く、より長時間使用できるロングドレイン油であることを示す。
表１に示すように、本発明の組成物（実施例１〜４）は上記ＩＳＯＴでの結果と同様、塩基価維持性に優れ、内燃機関用潤滑油等のＮＯｘに晒される雰囲気下においても優れたロングドレイン性を示すことがわかる。
【００８３】
（３）ファレックス試験でみた摩耗防止性
ＡＳＴＭ Ｄ３２３３に準拠するファレックス試験（Ａ法、２９０ｒｐｍ、室温において、試験片が焼付きを生じた時の荷重を測定した。その評価結果を表１に示す。焼付き荷重が大きいほど摩耗防止性に優れていることを示す。
表１に示すように、本発明の組成物は比較例１及び２の組成物に比べ同等以上の優れた摩耗防止性能を示すことがわかる。
【００８４】
（４）ホットチューブ試験でみた高温清浄性能
ＪＰＩ−５Ｓ−５５９９に準拠し、ホットチューブ試験を行った。評点は、無色透明（汚れなし）を１０点、黒色不透明を０点とし、この間を予め１刻みで作成した標準チューブを参照して評価した。２９０℃において当該評点が６以上であれば、通常のガソリンエンジン用、ディーゼルエンジン用の潤滑油として清浄性に優れたものであるが、ガスエンジン用の潤滑油としては、本試験において３００℃以上においても優れた清浄性を示すことが好ましい。
表１に示すように、本発明の組成物は、３００℃以上の試験条件においても、極めて優れた高温清浄性を示すことがわかる。特にトリオクチルホスフェートを使用した場合、トリブチルホスフェートよりも揮発性が低いと考えられ、極めて優れた高温清浄性を示す。
【００８５】
（実施例５〜９及び比較例３）
表２に示す組成及び性状の各内燃機関用潤滑油組成物（実施例５〜９及び比較例３）をそれぞれ調製し、下記の性能評価を行い、その結果を表２に示した。なお、実施例９の組成物は表１における実施例１の組成物と同一であり、比較例３の組成物は、表１における比較例１の組成物と同一である。
【００８６】
【表２】

【００８７】
（５）ＬＦＷ−１境界摩擦試験でみた低摩擦性能
ＬＦＷ−１試験機を用い、荷重１００ｌｂｓ、温度１００℃、様々な滑り速度でのＬＦＷ−１境界摩擦試験を行った。
表２の結果から明らかなように、実施例９の組成物（表１における実施例１の組成物）は、比較例３の組成物（表１における比較例１の組成物）と比べ低摩擦特性にも優れていることがわかる。また、（Ｃ）成分として、特に金属比の低いアルカリ土類金属サリシレートを必須として使用した場合（実施例５〜８）には、極めて優れた低摩擦性能を示すことがわかる。これらの組成物は、塩基価維持性、摩耗防止性、高温清浄性は実施例９の組成物と同等以上の性能を示す。なお、実施例６における（Ｃ）成分は、金属比１．０及び２．７のカルシウムサリシレートの混合物であり、その金属比は１．４６となるが、実施例５の組成物における（Ｃ）成分含有量を低減できるとともに、特に高滑り速度領域において相乗的に摩擦係数が低下していることが認められる。また、（Ａ）成分としてトリオクチルホスフェートに代えて、トリブチルホスフェート、トリフェニルホスフェートを使用した場合、比較例３と比べ低摩擦性能は優れているが、トリオクチルホスフェートが最も優れた低摩擦性能を示した。
【００８８】
【発明の効果】
本発明の内燃機関用潤滑油組成物は、ＺＤＴＰのような硫黄含有摩耗防止剤兼酸化防止剤を低減してもあるいは全く使用しなくても、摩耗防止性が低下することなく、酸化防止性が極めて向上し、塩基価維持性、すなわちロングドレイン性能に極めて優れ、かつ優れた高温清浄性、低摩擦性をも有する。
また、本発明の本発明の内燃機関用潤滑油組成物は、組成物の全硫黄分含有量を０．２質量％以下に低く抑えることができるので、排ガス浄化触媒等への硫黄による被毒を極めて低減することができ、排ガス浄化触媒等の排ガス後処理装置を装着したエンジンに好適に用いることができる。
また、本発明の内燃機関用潤滑油組成物は、前述のような硫黄分が５０質量ｐｐｍ以下の燃料、好ましくは２０質量ｐｐｍ以下、さらに好ましくは１０質量ｐｐｍ以下の燃料、例えば、ガソリンやＬＰＧ、天然ガス等を燃料として用いるエンジン、特にガスエンジンに適用することで、さらにロングドレイン性能を伸ばすことが可能となり、廃油問題や省資源に貢献することができる。
さらに、本発明の内燃機関用潤滑油組成物は摩耗防止性、塩基価維持性及び高温清浄性が必要とされる潤滑油、例えば、自動又は手動変速機等の駆動系用潤滑油、湿式ブレーキ、油圧作動油、タービン油、ギヤ油、軸受け油等の潤滑油としても好適に使用することができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a lubricating oil composition for an internal combustion engine, and more particularly to a lubricating oil composition for an internal combustion engine having excellent wear resistance, base number maintenance, high temperature cleanability and low friction.
[0002]
[Prior art]
Zinc dialkyldithiophosphate (ZDTP) has excellent anti-wear and antioxidant properties as a peroxide decomposer, and is used as an indispensable additive for all types of lubricating oils, including lubricating oils for internal combustion engines. Yes.
On the other hand, as a lubricating oil not using ZDTP, a lubricating oil composition containing zinc dialkyldithiocarbamate or a sulfur-based additive is known in order to maintain its wear prevention performance (see, for example, Patent Documents 1 to 7). .) The lubricating oil described in these patent documents contains a large amount of sulfur as in the lubricating oil containing ZDTP. Such lubricating oils generally have poor oxidation stability and tend to accelerate base number consumption (deterioration).
[0003]
[Patent Document 1]
JP-A-52-704
[Patent Document 2]
JP-A-62-253691
[Patent Document 3]
JP 62-501572A
[Patent Document 4]
JP-T 62-501917
[Patent Document 5]
Japanese Patent Laid-Open No. 63-304095
[Patent Document 6]
Japanese translation of PCT publication 1-500912
[Patent Document 7]
JP-A-6-41568
[0004]
[Problems to be solved by the invention]
The present inventor paid attention to the base number maintainability of a lubricating oil for internal combustion engines containing a large amount of sulfur, and as a result of earnest research, compounds containing sulfur such as ZDTP are lubricating oil when oxidized or thermally decomposed. It was found that sulfuric acid was generated in the product, which caused the base number to be consumed significantly and the life of the lubricating oil to be shortened. In addition, the cleanliness deteriorated particularly when used at high temperatures, and the low friction property was inferior. .
Especially for diesel engines equipped with DPF (diesel particulate filter), deep desulfurized diesel oil with sulfur content reduced to 50 mass ppm or less, kerosene, gasoline, LPG, natural gas with sulfur content of 50 mass ppm or less Or when hydrogen, dimethyl ether, alcohol, etc., which do not substantially contain sulfur, are used as fuel, the amount of sulfuric acid due to sulfur in the fuel is reduced in engine lubricating oil. Generally, the life of the lubricating oil is longer than when a sulfur-containing fuel is used. However, in order to make the engine oil longer drain and to further improve the high temperature cleanliness of the oil, it is not sufficient to use the low sulfur-containing fuel as described above, and sulfur-containing wear such as ZDTP. It has become necessary to study additives that replace antioxidants and antioxidants. In particular, gas engines generally have a high combustion temperature, and the lubricating oil is exposed to high temperatures and NOx, so that it is necessary to improve oxidation stability and high temperature cleanliness. Furthermore, in order to maintain the performance of exhaust gas purification devices such as DPF, three-way catalyst, oxidation catalyst, NOx occlusion reduction catalyst, EGR, etc., it is also desirable that the engine oil has a low sulfur content.
Accordingly, an object of the present invention is to maintain or further improve the wear prevention performance and oxidation prevention performance of conventionally used ZDTP, etc., and reduce the sulfur content in engine oil to reduce the base number associated with the deterioration of the oil. It is intended to provide a lubricating oil composition for an internal combustion engine that suppresses the consumption of oil and improves long drain performance and is excellent in high temperature cleanliness and low friction.
[0005]
[Means for Solving the Problems]
As a result of intensive studies to solve the above problems, the present inventors have found that a specific amount of a specific phosphorus compound, a specific ashless dispersant, a specific metal detergent and a specific antioxidant are added to the lubricating base oil. It has been found that by containing it, it is possible to obtain a lubricating oil that is excellent in wear resistance, improved base number maintenance and can be made long drain, and also excellent in high temperature cleanliness and low friction. It came to do.
[0006]
[Means for Solving the Problems]
Book The invention provides (A) a phosphoric acid triester represented by the general formula (1) in a lubricating base oil in an amount of 0.01 to 0.2% by mass in terms of phosphorus element, (B) succinimide and / or its 0.01 to 0.3% by mass of the derivative in terms of nitrogen element, (C) 0.05 to 1% by mass in terms of metal element of the alkali metal or alkaline earth metal detergent, and (D) phenolic It contains 0.01 to 3% by mass of an antioxidant and / or an amine antioxidant. And the detergent is a salicylate detergent having a metal ratio represented by the valence of metal element x metal element content (mol) / soap group content (mol) of 3 or less, and a dialkyldithiophosphoric acid Does not contain zinc (ZDTP) This is a lubricating oil composition for an internal combustion engine.
O = P (OR ¹ ) ₃ (1)
(Wherein R ¹ Represents a hydrocarbon group having 1 to 30 carbon atoms, which may be the same or different. )
[0009]
In the lubricating oil composition for an internal combustion engine of the present invention, the alkali metal or alkaline earth metal-based detergent is represented by the valence of metal element × metal element content (mol) / soap group content (mol). It is preferably a mixture of an alkali metal or alkaline earth metal salicylate detergent having a metal ratio of 1.5 or less and an alkali metal or alkaline earth metal salicylate detergent having a metal ratio of 1.5 or more.
[0010]
In the lubricating oil composition for an internal combustion engine of the present invention, the alkali metal or alkaline earth metal-based detergent is represented by the valence of metal element × metal element content (mol) / soap group content (mol). A mixture of an alkali metal or alkaline earth metal salicylate detergent having a metal ratio of 1.5 or less and an alkali metal or alkaline earth metal sulfonate detergent is preferred.
[0011]
The lubricating oil composition for an internal combustion engine of the present invention preferably further contains a sulfur-containing wear inhibitor having a content of 0.1% by mass or less in terms of elemental sulfur.
In the lubricating oil composition for an internal combustion engine of the present invention, the lubricating base oil preferably has a total aromatic content of 3 mass% or less and a sulfur content of 50 mass ppm or less.
The lubricating oil composition for an internal combustion engine of the present invention is preferably used for an internal combustion engine using a fuel having a sulfur content of 50 mass ppm or less.
The lubricating oil composition for an internal combustion engine of the present invention is preferably used for a gas engine.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
The lubricating base oil in the lubricating oil composition for internal combustion engines of the present invention is a commonly used mineral lubricating oil, synthetic lubricating oil or a mixture of any two or more kinds of lubricating oils selected from these. Such as one or more mineral oils, one or more synthetic oils, a mixture of one or more mineral oils and one or more synthetic oils, etc. Can be mentioned.
[0013]
Specifically, as the mineral oil-based lubricating oil, for example, a lubricating oil fraction obtained by subjecting crude oil to atmospheric distillation and vacuum distillation is subjected to solvent removal, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing. In addition, oils such as paraffinic and naphthenic oils, normal paraffins, etc., which are refined by appropriately combining one or two or more purification treatments such as hydrorefining, sulfuric acid washing, and clay treatment can be used. In particular, it is possible to use an advanced hydrocracking process capable of further reducing aromatics and sulfur content, or a product produced by isomerizing GTL Wax (gas-to-liquid wax). preferable.
Synthetic lubricating oil is not particularly limited. For example, poly-α-olefin (for example, 1-octene oligomer, 1-decene oligomer, ethylene-propylene oligomer, etc.) or a hydride thereof, isobutene oligomer or hydrogen thereof. Compounds, isoparaffins, alkylbenzenes, alkylnaphthalenes, diesters (eg, ditridecyl glutarate, di-2-ethylhexyl adipate, diisodecyl adipate, ditridecyl adipate, di-2-ethylhexyl sebacate), polyol esters (eg, trimethylolpropane caprylate) Trimethylolpropane pelargonate, pentaerythritol 2-ethylhexanoate, pentaerythritol pelargonate, etc.), polyoxyalkylene glycol, dia Kill ether, and polyphenyl ether and the like can be used.
[0014]
Although there is no restriction | limiting in particular in the sulfur content in lubricating base oil, It is preferable that it is 500 mass ppm or less, It is more preferable that it is 50 mass ppm or less, It is further more preferable that it is 20 mass ppm or less, 10 mass ppm It is particularly preferred that If the lubricating base oil contains a large amount of sulfur, it is not preferable because the base number maintenance property of the composition and the exhaust gas purification device are adversely affected.
The total aromatic content in the lubricating base oil is not particularly limited, but is preferably 15% by mass or less, more preferably 10% by mass or less, still more preferably 3% by mass or less, and 2% by mass or less. It is particularly preferred. When the total aromatic content of the base oil exceeds 15% by mass, it is not preferable because the base number maintenance property and the high temperature cleanability are inferior. In addition, the said total aromatic content means the aromatic fraction (aromatic fraction) content measured based on ASTMD2549. Usually, this aromatic fraction includes alkylbenzene, alkylnaphthalene, anthracene, phenanthrene, and alkylated products thereof, compounds in which four or more benzene rings are condensed, or pyridines, quinolines, phenols, naphthols, etc. Compounds having heteroaromatics and the like are included.
[0015]
The kinematic viscosity at 100 ° C. of the lubricating base oil is not particularly limited, but it is excellent in low-temperature viscosity characteristics and oil film formation at the lubricating location, and in order to reduce the evaporation loss of the lubricating base oil, 1-20 mm. ² / S, preferably 2 to 10 mm ² / S is particularly preferable.
The viscosity index of the lubricating base oil is not particularly limited, but is preferably 80 or more, more preferably 100 or more, and particularly preferably 120 or more.
[0016]
The component (A) in the lubricating oil composition for an internal combustion engine of the present invention is a phosphoric acid triester represented by the following general formula (1).
O = P (OR ¹ ) _Three (1)
R above ¹ Represents a hydrocarbon group having 1 to 30 carbon atoms. Three R ¹ May be the same or different.
As said C1-C30 hydrocarbon group, an alkyl group, a cycloalkyl group, an alkenyl group, an aryl group, and an arylalkyl group can be mentioned, for example.
[0017]
The alkyl group may be linear or branched, and specific examples thereof include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, Nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group and octadecyl group can be exemplified.
[0018]
The cycloalkyl group may have a substituent. Specific examples thereof include a cycloalkyl group having 5 to 7 carbon atoms such as a cyclopentyl group, a cyclohexyl group, and a cycloheptyl group; a methylcyclopentyl group. Dimethylcyclopentyl group, methylethylcyclopentyl group, diethylcyclopentyl group, methylcyclohexyl group, dimethylcyclohexyl group, methylethylcyclohexyl group, diethylcyclohexyl group, methylcycloheptyl group, dimethylcycloheptyl group, methylethylcycloheptyl group, diethylcycloheptyl group And an alkylcycloalkyl group having 6 to 11 carbon atoms such as a group (the substitution position of the alkyl group is also arbitrary).
[0019]
The alkenyl group may be linear or branched, and specific examples thereof include a butenyl group, a pentenyl group, a hexenyl group, a heptenyl group, an octenyl group, and a nonenyl group. Group, decenyl group, undecenyl group, dodecenyl group, tridecenyl group, tetradecenyl group, pentadecenyl group, hexadecenyl group, heptadecenyl group, and octadecenyl group, etc. (positions of double bonds of these alkenyl groups) Are also optional).
[0020]
The aryl group may be substituted with an alkyl group, and specific examples thereof include aryl groups having 6 to 18 carbon atoms such as phenyl group and naphthyl group: tolyl group, xylyl group, ethylphenyl group. Group, propylphenyl group, butylphenyl group, pentylphenyl group, hexylphenyl group, heptylphenyl group, octylphenyl group, nonylphenyl group, decylphenyl group, undecylphenyl group, dodecylphenyl group, diethylphenyl group, dibutylphenyl group And an alkylaryl group having 7 to 26 carbon atoms such as a dioctylphenyl group (the alkyl group may be linear or branched, and the substitution position on the aryl group is also optional).
[0021]
Specific examples of the arylalkyl group include arylalkyl groups having 7 to 12 carbon atoms such as benzyl group, phenylethyl group, phenylpropyl group, phenylbutyl group, phenylpentyl group, and phenylhexyl group (these The alkyl group may be linear or branched).
[0022]
R above ¹ Is preferably a linear or branched alkyl group having 3 to 18 carbon atoms, an aryl group having 6 to 18 carbon atoms, or a linear or branched alkylaryl group. In particular, it is preferably an alkyl group having 3 to 5 carbon atoms from the viewpoint of excellent base number maintenance, and a linear or branched alkyl group having 6 to 18 carbon atoms from the viewpoint of excellent high-temperature cleanability. , An aryl group having 6 to 10 carbon atoms or a linear or branched alkylaryl group is preferable. In the present invention, when it is a linear or branched alkyl group having 6 to 18 carbon atoms, preferably 6 to 12 carbon atoms, it has low volatility and is most excellent in high temperature cleanliness and friction reduction effect. Is desirable. R ¹ Are preferably the same.
[0023]
By using the phosphoric acid triester represented by the general formula (1), the metal content of the composition can be further reduced as compared with the case where a metal wear inhibitor such as ZDTP is used. As compared with the case where phosphoric acid monoester or diester or phosphite is used, a lubricating oil composition having higher wear resistance, base number maintenance and high temperature cleanability can be obtained.
[0024]
The lower limit of the content of the component (A) in the present invention is 0.01% by mass in terms of phosphorus element, preferably 0.02% by mass, and 0.05% by mass based on the total amount of the composition. % Is particularly preferred. On the other hand, the upper limit is 0.2% by mass in terms of phosphorus element, preferably 0.15% by mass, particularly preferably 0.1% by mass, based on the total amount of the composition. When the content of the component (A) is less than 0.01% by mass, the sufficient effect of the present invention cannot be obtained. On the other hand, when the content of the component (A) exceeds 0.2% by mass, the exhaust gas purification catalyst or the like is obtained. It is not preferable because the influence of
[0025]
(B) component in the lubricating oil composition for internal combustion engines of this invention is a succinimide and / or its derivative (s).
Examples of the succinimide include monosuccinimide represented by the following general formula (2), bissuccinimide represented by the general formula (3), and the like.
[0026]
[Chemical 1]

[0027]
[Chemical formula 2]

[0028]
In general formula (2) or (3), R ^Ten , R ¹¹ And R ¹² Each independently represents a polybutenyl group, and n represents an integer of 2 to 7. In this invention, it is preferable that it is a bis type | mold succinimide represented by General formula (3) at the point which can improve the effect of this invention more.
R above ^Ten , R ¹¹ And R ¹² The number average molecular weight of the polybutenyl group represented by is preferably 700 or more, more preferably 900 or more, while the number average molecular weight of the polybutenyl group is preferably 3500 or less, more preferably 2500. Hereinafter, it is particularly preferably 1500 or less. By setting the number average molecular weight to 700 or more, it becomes possible to obtain a lubricating oil composition that is more excellent in cleanliness and dispersibility. On the other hand, by setting the number average molecular weight to 3500 or less, it becomes possible to obtain a lubricating oil composition having better low temperature fluidity. From the viewpoint of excellent sludge suppression effect, the lower limit value of n is 2, preferably 3, while the upper limit value of n is 7, preferably 6. Here, the polybutenyl group can be obtained from polybutene (polyisobutene) obtained by polymerizing a mixture of 1-butene and isobutene or high-purity isobutene with a catalyst such as aluminum chloride or boron fluoride. What has a vinylidene structure is contained normally 5-100 mol%. Further, as this polybutene (polyisobutene), it is also possible to use a product obtained by removing a trace amount of remaining fluorine and chlorine by an appropriate treatment method due to the catalyst in the production process. The content of halogen elements such as chlorine is preferably 50 ppm by mass or less, more preferably 10 ppm by mass or less, still more preferably 5 ppm by mass or less, and particularly preferably 1 ppm by mass or less.
[0029]
There is no restriction | limiting in particular in the manufacturing method of succinimide represented by General formula (2) or (3). For example, polybutenyl succinic acid obtained by reacting chlorinated polybutene, preferably polybutene from which chlorine and fluorine have been sufficiently removed, with maleic anhydride at 100 to 200 ° C. is converted into diethylenetriamine, triethylenetetramine, tetra A method of reacting with a polyamine such as ethylenepentamine or pentaethylenehexamine can be used. In the case of producing bissuccinimide, the polybutenyl succinic acid may be reacted twice as much as the polyamine (molar ratio). In the case of producing monosuccinimide, the polybutenyl succinic acid and the polyamine are used. May be reacted in an equal amount (molar ratio).
[0030]
Examples of the succinimide derivative include a residual amino group and / or imino group obtained by allowing an oxygen-containing organic compound or boron compound to act on the compound represented by the general formula (2) or (3). The compound which neutralized a part or all or amidated may be sufficient.
Specific examples of the oxygen-containing organic compound include formic acid, acetic acid, glycolic acid, propionic acid, lactic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, undecylic acid, C 1-30 monocarboxylic acids such as lauric acid, tridecanoic acid, myristic acid, pentadecanoic acid, palmitic acid, margaric acid, stearic acid, oleic acid, nonadecanoic acid, eicosanoic acid; oxalic acid, phthalic acid, trimellitic acid And C2-C30 polycarboxylic acids such as pyromellitic acid or their anhydrides or ester compounds; C2-C6 alkylene oxides; hydroxy (poly) oxyalkylene carbonates, and the like. By allowing such an oxygen-containing organic compound to act, for example, when a part or all of the amino group or imino group in the compound of the general formula (2) or (3) has a structure represented by the following general formula (4) Presumed.
[0031]
[Chemical 3]

[0032]
Where R ¹³ Is a hydrogen atom, an alkyl group having 1 to 24 carbon atoms, an alkenyl group, an alkoxy group, or -O- (R ¹⁴ O) _m R represents a hydroxy (poly) oxyalkylene group represented by H, R ¹⁴ Represents an alkylene group having 1 to 4 carbon atoms, and m represents an integer of 1 to 5.
[0033]
Examples of the boron compound include boric acid, borates, and borate esters. Specific examples of boric acid include orthoboric acid, metaboric acid, and tetraboric acid. Examples of borates include alkali metal salts, alkaline earth metal salts or ammonium salts of boric acid, and more specifically, for example, lithium metaborate, lithium tetraborate, lithium pentaborate, perborate. Lithium borate such as lithium; sodium borate such as sodium metaborate, sodium diborate, sodium tetraborate, sodium pentaborate, sodium hexaborate, sodium octaborate; potassium metaborate, potassium tetraborate, Potassium borates such as potassium pentaborate, potassium hexaborate and potassium octaborate; calcium borates such as calcium metaborate, calcium diborate, tricalcium tetraborate, pentacalcium tetraborate and calcium hexaborate ; Magnesium metaborate, magnesium diborate, trimagnesium tetraborate, pentaborate Neshiumu, magnesium borate and magnesium hexaborate acid; and ammonium metaborate, ammonium tetraborate, ammonium pentaborate and ammonium borate such as ammonium eight borate. Examples of the boric acid ester include esters of boric acid and preferably an aliphatic alcohol having 1 to 6 carbon atoms. More specifically, examples include boric acid monomethyl, boric acid dimethyl, boric acid trimethyl, boric acid ester. Examples thereof include monoethyl acid, diethyl borate, triethyl borate, monopropyl borate, dipropyl borate, tripropyl borate, monobutyl borate, dibutyl borate, and tributyl borate.
[0034]
The succinimide to which the boron compound is allowed to act is not particularly limited in the mass ratio (B / N ratio) of the boron content and the nitrogen content, but it is 0.1 to 1 from the viewpoint of improving the base number maintenance and the high temperature cleanability. .2 is preferable, 0.2 to 1.0 is more preferable, and 0.3 to 0.9 is particularly preferable.
[0035]
In this invention, 1 type (s) or 2 or more types chosen from the said succinimide and its derivative (s) can be used as (B) component.
[0036]
The lower limit of the content of the component (B) in the present invention is 0.01% by mass, preferably 0.05% by mass, and 0.08% by mass in terms of nitrogen element, based on the total amount of the composition. % Is particularly preferred. On the other hand, the upper limit is 0.3% by mass in terms of nitrogen element, preferably 0.2% by mass, and particularly preferably 0.15% by mass, based on the total amount of the composition. When the content of the component (B) is less than 0.01% by mass, the effect of the present invention cannot be obtained, and when the content exceeds 0.3% by mass, the low-temperature viscosity characteristics and demulsification of the composition Since the properties deteriorate, it is not preferable.
[0037]
The component (C) in the present invention is an alkali metal or alkaline earth metal detergent. This component (C) includes alkali metal or alkaline earth metal sulfonate, alkali metal or alkaline earth metal phenate, alkali metal or alkaline earth metal salicylate, and the like. In the present invention, one or more alkali metal or alkaline earth metal detergents selected from the group consisting of these, particularly alkaline earth metal detergents can be preferably used.
[0038]
Alkaline earth metal sulfonates include alkyl earth sulfonic acid alkaline earth metal salts obtained by sulfonated alkyl aromatic compounds having a molecular weight of 300 to 1500, preferably 400 to 700, particularly magnesium salts and / or calcium. It is a salt, and a calcium salt is preferably used.
Specific examples of the alkyl aromatic sulfonic acid include so-called petroleum sulfonic acid and synthetic sulfonic acid.
As said petroleum sulfonic acid, what sulfonated the alkyl aromatic compound of the lubricating oil fraction of mineral oil, what is called mahoganic acid etc. byproduced at the time of white oil manufacture are generally used. As the synthetic sulfonic acid, for example, a straight chain obtained as a by-product from an alkylbenzene production plant that is a raw material for detergents or obtained by alkylating an oligomer of an olefin having 2 to 12 carbon atoms (ethylene, propylene, etc.) to benzene. A sulfonated alkylbenzene having a linear or branched alkyl group or a sulfonated alkylnaphthalene such as dinonylnaphthalene is used. The sulfonating agent for sulfonating these alkyl aromatic compounds is not particularly limited, but fuming sulfuric acid or sulfuric anhydride is usually used.
[0039]
Examples of alkaline earth metal phenates include alkylphenols, alkylphenol sulfides, alkaline earth metal salts of Mannich reactants of alkylphenols, particularly magnesium salts and calcium salts. Specific examples include those represented by the following general formulas (5), (6) and (7).
[0040]
[Formula 4]

[0041]
[Chemical formula 5]

[0042]
[Chemical 6]

[0043]
In the general formulas (5), (6), and (7), R ^{twenty one} , R ^{twenty two} , R ^{twenty three} , R ^{twenty four} , R ^{twenty five} And R ²⁶ Each may be the same or different and each represents a linear or branched alkyl group having 4 to 30 carbon atoms, preferably 6 to 18 carbon atoms. ¹ , M ² And M ^Three Each represents an alkaline earth metal, preferably calcium or magnesium, and x represents 1 or 2.
[0044]
R above ^{twenty one} , R ^{twenty two} , R ^{twenty three} , R ^{twenty four} , R ^{twenty five} And R ²⁶ Specific examples of the alkyl group represented by the above are butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group. , Pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, icosyl group, heicosyl group, docosyl group, tricosyl group, tetracosyl group, pentacosyl group, hexacosyl group, heptacosyl group, octacosyl group, nonacosyl group, triaconyl group, etc. Is mentioned. These may be linear or branched. These may also be primary alkyl groups, secondary alkyl groups or tertiary alkyl groups.
[0045]
Examples of the alkaline earth metal salicylates include alkaline earth metal salts of allyl salicylic acid, particularly magnesium salts and calcium salts. Specific examples include compounds represented by the following general formula (8).
[0046]
[Chemical 7]

[0047]
In the general formula (8), R ²⁷ Represents a linear or branched alkyl group having 4 to 30 carbon atoms, preferably 6 to 18 carbon atoms, and M ^Four Represents an alkaline earth metal, preferably calcium or magnesium.
R above ²⁷ As the alkyl group represented by, specifically, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, Hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, icosyl group, henecosyl group, docosyl group, tricosyl group, tetracosyl group, pentacosyl group, hexacosyl group, heptacosyl group, octacosyl group, nonacosyl group, triacontyl group, etc. May be linear or branched. These may also be primary alkyl groups, secondary alkyl groups or tertiary alkyl groups.
[0048]
Alkaline earth metal sulfonates, alkaline earth metal phenates and alkaline earth metal salicylates can be obtained by directly using the above-mentioned alkyl aromatic sulfonic acids, alkylphenols, alkylphenol sulfides, Mannich reactants of alkylphenols, alkylsalicylic acid, etc., magnesium and / or calcium. It can be obtained by reacting with an alkaline earth metal base such as an alkaline earth metal oxide or hydroxide, or by replacing it with an alkaline earth metal salt such as a sodium salt or potassium salt, and then substituting it with an alkaline earth metal salt. Neutral (normal salt) alkaline earth metal sulfonates, neutral (normal salt) alkaline earth metal phenates and neutral (normal salt) alkaline earth metal salicylates; or neutral alkaline earth metal sulfonates, neutral alkaline earth Metal phenates and medium Basic alkaline earth metal sulfonate, basic alkaline earth metal phenate and basic alkali obtained by heating alkaline earth metal salicylate and excess alkaline earth metal salt or alkaline earth metal base in the presence of water Earth metal salicylates; and in the presence of neutral alkaline earth metal sulfonates, neutral alkaline earth metal phenates and neutral alkaline earth metal salicylates, alkaline earth metal hydroxides and carbon dioxide or boric acid Also includes overbased (superbasic) alkaline earth metal sulfonates, overbased (superbasic) alkaline earth metal phenates and overbased (superbasic) alkaline earth metal salicylates obtained by reacting It is.
[0049]
In the present invention, the above-mentioned neutral alkaline earth metal salts, basic alkaline earth metal salts, overbased (superbasic) alkaline earth metal salts, mixtures thereof, and the like can be used. The total base number is usually 500 mgKOH / g or less, preferably 60 to 400 mgKOH / g. Here, the total base number is the same as that described in “7. It means the total base number measured by the perchloric acid method based on
Alkaline earth metal detergents are usually commercially available in a state diluted with a light lubricating base oil or the like, and are available, but generally the metal content is 1.0 to 20% by mass. Preferably, 2.0 to 16% by mass is used.
[0050]
Although there is no restriction | limiting in particular as a metal ratio of (C) component used for this invention, Usually, 1-20, Preferably the thing of 1-15 is used.
In the present invention, as the component (C), an alkali metal or alkaline earth metal salicylate detergent is preferably contained as an essential component. The metal ratio is preferably 3 or less, more preferably 2.6 or less, further preferably 2 or less, and particularly preferably 1.5 or less. Such alkali metal or alkaline earth metal salicylate-based detergents may be used alone or in combination with different metal ratios. For example, an alkali metal or alkaline earth metal salicylate having a metal ratio of 2 or less, preferably 1.5 or less, particularly 1.2 or less, can be used alone as an essential component, or a metal ratio of 1.5 or less, preferably 1.2 or less and a metal ratio exceeding 1.5, especially those exceeding 2.6, the metal ratio in the alkali metal or alkaline earth metal salicylate mixture is 1.3 or more, preferably It may be prepared to 2.3 or less, more preferably 2 or less, and particularly preferably 1.5 or less. By adjusting the metal ratio of the alkali metal or alkaline earth metal salicylate to the range of 1.3 to 2.3, the base number maintenance property, the high temperature cleanliness, and further the low friction property with respect to the content of the component (C) The improvement effect can be further enhanced.
[0051]
The component (C) comprises an alkali metal or alkaline earth metal salicylate detergent having a metal ratio of 1.5 or less, preferably 1.2 or less, and an alkali metal or alkaline earth metal sulfonate detergent. It is preferable to use together. The metal ratio of the alkali metal or alkaline earth metal sulfonate detergent is not particularly limited, but is usually 1 to 20, preferably 1 to 15, particularly preferably 5 to 12. By making (C) component into such a structure, the improvement effect of base number maintenance property, high temperature detergency, and also low friction property can be heightened more.
[0052]
The metal ratio here is represented by the valence of metal element × metal element content (mol) / soap group (that is, group such as alkyl salicylic acid group) content (mol). The alkali metal or alkaline earth metal content relative to the alkyl salicylic acid group or alkyl sulfonic acid group content in the alkali metal or alkaline earth metal detergent is shown.
[0053]
The lower limit of the content of the alkali metal or alkaline earth metal detergent (C) in the present invention is 0.05% by mass in terms of alkali metal or alkaline earth metal element, based on the total amount of the composition, Preferably it is 0.1 mass%, More preferably, it is 0.15 mass%, Most preferably, it is 0.2 mass%. On the other hand, the upper limit is 1% by mass, preferably 0.5% by mass, more preferably 0.4% by mass in terms of alkali metal or alkaline earth metal element, based on the total amount of the composition. When the content of the component (C) is less than 0.05% by mass, the excellent base number maintainability and the high temperature cleanability as in the present invention cannot be exhibited, while the content of the component (C) is 1% by mass. When exceeding, since the effect only corresponding to content is not acquired, it is unpreferable respectively.
[0054]
(D) component in the lubricating oil composition for internal combustion engines of this invention is a phenolic antioxidant and / or an amine antioxidant.
Examples of phenolic antioxidants include 4,4′-methylenebis (2,6-di-tert-butylphenol), 4,4′-bis (2,6-di-tert-butylphenol), 4,4 ′. -Bis (2-methyl-6-tert-butylphenol), 2,2'-methylenebis (4-ethyl-6-tert-butylphenol), 2,2'-methylenebis (4-methyl-6-tert-butylphenol), 4,4′-butylidenebis (3-methyl-6-tert-butylphenol), 4,4′-isopropylidenebis (2,6-di-tert-butylphenol), 2,2′-methylenebis (4-methyl-6) -Nonylphenol), 2,2'-isobutylidenebis (4,6-dimethylphenol), 2,2'-methylenebis (4-methyl-6-cyclohexene) Xylphenol), 2,6-di-tert-butyl-4-methylphenol, 2,6-di-tert-butyl-4-ethylphenol, 2,4-dimethyl-6-tert-butylphenol, 2,6- Di-tert-α-dimethylamino-p-cresol, 2,6-di-tert-butyl-4 (N, N′-dimethylaminomethylphenol), 4,4′-thiobis (2-methyl-6-tert) -Butylphenol), 4,4'-thiobis (3-methyl-6-tert-butylphenol), 2,2'-thiobis (4-methyl-6-tert-butylphenol), bis (3-methyl-4-hydroxy-) 5-tert-butylbenzyl) sulfide, bis (3,5-di-tert-butyl-4-hydroxybenzyl) sulfide, 2,2′-thio-di Ethylenebis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], tridecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, pentaerythrityl- Tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, octyl-3- ( Preferred specific examples include 3,5-di-tert-butyl-4-hydroxyphenyl) propionate, octyl-3- (3-methyl-5-tert-butyl-4-hydroxyphenyl) propionate and the like. You may use these in mixture of 2 or more types.
[0055]
Examples of amine-based antioxidants include phenyl-α-naphthylamine, alkylphenyl-α-naphthylamine, and dialkyldiphenylamine. You may use these in mixture of 2 or more types. In addition, an alkyl group here shows a C1-C16 alkyl group generally.
Although the said phenolic antioxidant and amine antioxidant may be used independently, since the effect of this invention can be improved more, it is preferable to mix | blend and mix | blend.
[0056]
In the lubricating oil composition of the present invention, the lower limit of the content of the component (D) is 0.01% by mass based on the total amount of the composition in order to further improve the base number maintenance property and the high temperature cleanability, and is preferably 0.00. It is 1% by mass, more preferably 0.5% by mass, and particularly preferably 1.0% by mass. On the other hand, the upper limit of the content of the component (D) is 3.0% by mass, preferably 2.5% by mass, based on the total amount of the composition. It is not preferable because sufficient antioxidant properties can not be obtained.
[0057]
An anti-wear agent other than the component (A) can be blended in the lubricating oil composition for an internal combustion engine of the present invention.
As the anti-wear agent other than the component (A), a thiophosphate ester or a metal salt of a phosphate ester represented by the following general formula (9), a thiophosphate ester or a phosphate ester represented by the following general formula (10) In addition to the metal salt or amine salt thereof, phosphite ester or thiophosphite ester, or metal salt or amine salt thereof, thiophosphate triester or zinc dialkyldithiophosphate, zinc dialkyldithiocarbamate, molybdenum dialkyldithiophosphate, Examples thereof include phosphorus and / or sulfur-containing wear inhibitors such as molybdenum dialkyldithiocarbamate, disulfide, sulfurized olefin, and sulfurized fats and oils.
[0058]
[Chemical 8]

[0059]
[Chemical 9]

[0060]
R above ³⁰ , R ³¹ , R ³² , R ³³ , R ³⁴ And R ³⁵ Each independently represents a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms, and examples of the hydrocarbon group having 1 to 30 carbon atoms include R in the general formula (1) of the component (A). ¹ The preferred range is also synonymous.
[0061]
X above ¹ , X ² , X ^Three , X ^Four , X ^Five And X ⁶ Each independently represents an oxygen atom or a sulfur atom, at least one of which is an oxygen atom, preferably two or more are oxygen atoms, and particularly preferably all are oxygen atoms. By containing at least one oxygen atom, the sulfur content in the composition can be further reduced, and the amount of sulfuric acid generated when subjected to oxidation or thermal decomposition can be reduced. Can do.
[0062]
Specific examples of the metal atom represented by Y include zinc, copper, iron, lead, nickel, silver, and manganese. From the viewpoint of obtaining higher wear prevention performance, Y is preferably zinc.
U represents hydrogen (proton), a monovalent metal ion, or an ammonium ion, k is an integer of 1 to 20, and represents the number of U ions. k is preferably an integer of 1 to 10. More preferably, it is an integer of 1-8.
The monovalent metal ion represented by U is a metal atom that can form a salt, and examples thereof include alkali metals such as lithium, sodium, potassium, and cesium. Ammonium ions can include compounds derived from these ions, for example, nitrogen-containing compounds that can form amine salts.
[0063]
Examples of the nitrogen-containing compound include ammonia, monoamine, diamine, and polyamine. More specifically, methylamine, ethylamine, propylamine, butylamine, pentylamine, hexylamine, heptylamine, octylamine, nonylamine, decylamine, undecylamine, dodecylamine, tridecylamine, tetradecylamine, pentadecylamine , Hexadecylamine, heptadecylamine, octadecylamine, dimethylamine, diethylamine, dipropylamine, dibutylamine, dipentylamine, dihexylamine, diheptylamine, dioctylamine, dinonylamine, didecylamine, diundecylamine, didodecylamine, ditridecylamine Decylamine, ditetradecylamine, dipentadecylamine, dihexadecylamine, diheptadecylamine, dioctadecylamine, methyl ethyl Amine, methylpropyl amine, alkyl amines having methylbutylamine, ethylpropylamine, ethylbutylamine, alkyl group having 1 to 30 carbon atoms such as propyl butyl amine (the alkyl groups may be and straight-chain or branched);
[0064]
Alkenylamines having 2 to 30 carbon atoms such as ethenylamine, propenylamine, butenylamine, octenylamine, oleylamine (these alkenyl groups may be linear or branched); methanolamine, ethanolamine, propanolamine, 1 to C carbon atoms such as butanolamine, pentanolamine, hexanolamine, heptanolamine, octanolamine, nonanolamine, methanol ethanolamine, methanolpropanolamine, methanolbutanolamine, ethanolpropanolamine, ethanolbutanolamine, propanolbutanolamine An alkanolamine having 30 alkanol groups (these alkanol groups may be linear or branched);
[0065]
Alkylene diamines having an alkylene group having 1 to 30 carbon atoms such as methylene diamine, ethylene diamine, propylene diamine, butylene diamine; polyamines such as diethylene triamine, triethylene tetramine, tetraethylene pentamine, pentaethylene hexamine; undecyldiethylamine, undecyldiethanolamine , Dodecyldipropanolamine, oleyldiethanolamine, oleylpropylenediamine, stearyltetraethylenepentamine and the like monoamines, diamines, polyamines having a C8-20 alkyl group or alkenyl group, N-hydroxyethyloleylimidazoline, etc. Examples include heterocyclic compounds; alkylene oxide adducts of these compounds; and mixtures thereof.
[0066]
In the lubricating oil composition for internal combustion engines of the present invention, among the anti-wear agents other than the component (A), when an anti-wear agent containing sulfur is contained, the content is not particularly limited, In terms of the total amount of the composition, it is preferably 0.1% by mass or less, more preferably 0.09% by mass or less in terms of sulfur element. It is particularly preferred not to contain a sulfur-containing wear inhibitor. By making the sulfur-containing antiwear agent 0.1% by mass or less, it becomes possible to obtain a composition having extremely excellent base number maintenance and high-temperature cleanability.
In addition, among the anti-wear agents other than the above component (A), when a phosphorus-containing anti-wear agent containing no sulfur is contained, the content is usually 0.005 in terms of phosphorus element, based on the total amount of the composition. 01 to 0.2% by mass. Even in that case, it is preferable that the phosphorus element conversion amount in the composition does not exceed 0.2% by mass in combination with the component (A) because there is a concern about adverse effects on the exhaust gas purification catalyst and the like, and 0.15% by mass It is particularly preferred not to exceed.
[0067]
The lubricating oil composition for an internal combustion engine of the present invention is excellent in wear prevention, base number maintenance and high temperature cleanability, but in order to further improve its performance, an optional additive is added depending on the purpose. Can be added. Examples of such additives include a viscosity index improver, an ashless dispersant other than the component (B), a metal detergent other than the component (C), a friction modifier, a corrosion inhibitor, a rust inhibitor, and an anti-emulsifier. , Metal deactivators, antifoaming agents, and coloring agents.
[0068]
Specific examples of the viscosity index improver include a so-called non-dispersed viscosity index improver such as a copolymer of one or more monomers selected from various methacrylic esters or a hydrogenated product thereof, or nitrogen. So-called dispersion-type viscosity index improver, non-dispersion-type or dispersion-type ethylene-α-olefin copolymer obtained by copolymerizing various methacrylic acid esters containing compounds (α-olefin includes propylene, 1-butene, 1-pentene, etc. Or a hydrogenated product thereof, polyisobutylene or a hydrogenated product thereof, a styrene-diene hydrogenated copolymer, a styrene-maleic anhydride ester copolymer, and a polyalkylstyrene.
The molecular weight of these viscosity index improvers is preferably selected in consideration of shear stability. Specifically, the number average molecular weight of the viscosity index improver is, for example, 5,000 to 1,000,000, preferably 10,000 to 350,000 in the case of dispersed and non-dispersed polymethacrylates. In the case of polyisobutylene or a hydride thereof, 800 to 5,000, preferably 1,000 to 4,000, and in the case of an ethylene-α-olefin copolymer or a hydride thereof, 800 to 500,000, Preferably the thing of 3,000-200,000 is desirable.
Further, among these viscosity index improvers, when an ethylene-α-olefin copolymer or a hydride thereof is used, a lubricating oil composition particularly excellent in shear stability can be obtained. One or two or more compounds arbitrarily selected from the above viscosity index improvers can be contained in any amount. The content of the viscosity index improver is usually 0.1 to 20.0% by mass based on the total amount of the lubricating oil composition.
[0069]
Examples of the ashless dispersant other than the component (B) include benzylamine, polyamine and derivatives thereof having at least one alkyl group or alkenyl group having 40 to 400 carbon atoms in the molecule.
[0070]
Examples of the friction modifier include aliphatic amines having 6 to 30 carbon atoms or alkenyl groups, fatty acids, fatty acid esters, and aliphatic alcohols.
[0071]
Examples of the corrosion inhibitor include benzotriazole, tolyltriazole, thiazole, thiadiazole, and imidazole compounds.
[0072]
Examples of the rust inhibitor include petroleum sulfonate, alkylbenzene sulfonate, dinonylnaphthalene sulfonate, alkenyl succinic acid ester, and polyhydric alcohol ester.
[0073]
Examples of the demulsifier include polyalkylene glycol nonionic surfactants such as polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, and polyoxyethylene alkyl naphthyl ether.
[0074]
Examples of metal deactivators include imidazoline, pyrimidine derivatives, alkylthiadiazoles, mercaptobenzothiazoles, benzotriazoles or derivatives thereof, 1,3,4-thiadiazole polysulfide, 1,3,4-thiadiazolyl-2,5-bis. Examples include dialkyldithiocarbamate, 2- (alkyldithio) benzimidazole, and β- (o-carboxybenzylthio) propiononitrile.
[0075]
Examples of the antifoaming agent include silicone, fluorosilicone, and fluoroalkyl ether.
[0076]
When these additives are contained in the lubricating oil composition of the present invention, the content is based on the total amount of the lubricating oil composition, and an ashless dispersant other than the component (B), and a metal-based detergent other than the component (C). Agent, antioxidant other than component (D), friction modifier, corrosion inhibitor, rust inhibitor, demulsifier, 0.01 to 5% by weight, and metal deactivator 0.005 to 1% by weight, In the case of an antifoaming agent, it is usually selected in the range of 0.0005 to 1% by mass.
[0077]
The lubricating oil composition for an internal combustion engine of the present invention preferably restricts the content of an additive containing sulfur together with the above-described sulfur-containing wear inhibitor, and contains a sulfur-containing additive (including a sulfur-containing wear inhibitor). ) In terms of the total amount of the composition, in terms of elemental sulfur, is preferably 0.1% by mass or less, more preferably 0.09% by mass or less, and a sulfur-containing additive (sulfur-containing) It is particularly preferred not to contain an anti-wear agent). Commercially available additives generally contain a solvent used when synthesizing the additive and a diluent oil (for example, a solvent refined mineral oil) for improving the handling of the additive. The sulfur-containing additive in the above does not mean a sulfur compound resulting from these solvents or diluent oil.
[0078]
In the present invention, even if the sulfur content resulting from these solvents and diluent oil is contained, the total sulfur content in the composition is 0.2% by mass or less, preferably 0.15% by mass or less, particularly Preferably it is 0.1 mass% or less. Thereby, the composition which was excellent in abrasion prevention property, base number maintenance property, and high temperature detergency, and also maintained performances, such as an exhaust gas purification catalyst, is obtained. In the present invention, these solvents and diluent oils are highly hydrocracked base oils having a sulfur content of 10 ppm by mass or less, or GTL Wax (gas-to-liquid wax) containing substantially no sulfur content. A composition in which the total sulfur content in the composition is 10 mass ppm or less by using a base oil or the like produced by an isomerization technique, or a synthetic oil, and not containing a sulfur-containing additive, or substantially It is also possible to obtain a composition that does not contain it.
[0079]
【Example】
The present invention will be described more specifically with reference to examples and comparative examples below, but the present invention is not limited to these examples.
(Examples 1 to 4 and Comparative Examples 1 and 2)
Lubricating oil compositions for internal combustion engines (Examples 1 to 4 and Comparative Examples 1 and 2) having the compositions and properties shown in Table 1 were prepared. In addition, the thing whose sulfur content in a composition is 0.05 mass% originates in the diluent oil of an additive.
[0080]
[Table 1]

[0081]
The performance of the lubricating oil compositions for internal combustion engines obtained in Examples 1 to 4 and Comparative Examples 1 and 2 was evaluated by the following performance evaluation test.
(1) Change in total base number with time due to ISOT
The time course of the total base number (hydrochloric acid method) when the test oil was forcibly deteriorated by an ISOT test (165.5 ° C.) based on JIS K 2514 was measured. The evaluation results are shown in Table 1. The higher the total base number residual ratio, the higher the base number maintenance performance, indicating a longer drain oil that can be used for a longer time.
As shown in Table 1, in the compositions of the present invention (Examples 1 to 4), ZDTP (sulfur-containing antiwear agent) is generally used as a lubricating oil for internal combustion engines (the amount of elemental sulfur, 0.16 mass). %, The amount of phosphorus element is 0.08% by mass), and it can be seen that the base number maintainability is extremely high as compared with the composition (Comparative Examples 1 and 2). Above all, it can be seen that the triphenyl phosphate-containing composition (Example 4) and especially the tributyl phosphate-containing composition (Example 3) have a very high base number retention compared to the trioctyl phosphate-containing composition (Example 1). .
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(2) Temporal change of total base number by NOx absorption test
Measure changes over time in total base number (hydrochloric acid method) when NOx gas is blown into test oil and forcedly deteriorated under conditions (150 ° C, NOx: 1185 ppm) in accordance with 1992, 10, 465 did. The evaluation results are shown in Table 1. The smaller the decrease in the total base number, the higher the base number maintaining performance even in the presence of NOx used in an internal combustion engine, indicating a long drain oil that can be used for a longer time.
As shown in Table 1, the compositions of the present invention (Examples 1 to 4) are excellent in base number maintenance, similar to the results of the above ISOT, and even in an atmosphere exposed to NOx such as lubricating oil for internal combustion engines. It can be seen that an excellent long drain property is exhibited.
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(3) Abrasion prevention in the Falex test
Falex test in accordance with ASTM D3233 (A method, 290 rpm, the load when the test piece was seized at room temperature was measured. The evaluation result is shown in Table 1. The larger the seizure load, the more the anti-wear property. It is excellent in.
As shown in Table 1, it can be seen that the composition of the present invention exhibits the same or better anti-wear performance than the compositions of Comparative Examples 1 and 2.
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(4) High temperature cleaning performance from hot tube test
A hot tube test was conducted in accordance with JPI-5S-5599. The rating was 10 points for colorless and transparent (no stain) and 0 points for black opaque, and the evaluation was made with reference to a standard tube prepared in advance by 1 interval. If the score is 6 or more at 290 ° C., it is excellent in cleanliness as a lubricating oil for ordinary gasoline engines and diesel engines, but as a lubricating oil for gas engines, it is 300 ° C. or higher in this test. It is preferable to show excellent cleanliness.
As shown in Table 1, it can be seen that the composition of the present invention exhibits extremely excellent high-temperature cleanability even under test conditions of 300 ° C. or higher. In particular, when trioctyl phosphate is used, the volatility is considered to be lower than that of tributyl phosphate, and extremely high temperature cleanability is exhibited.
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(Examples 5 to 9 and Comparative Example 3)
The internal combustion engine lubricating oil compositions (Examples 5 to 9 and Comparative Example 3) having the compositions and properties shown in Table 2 were prepared, and the following performance evaluations were performed. The results are shown in Table 2. In addition, the composition of Example 9 is the same as the composition of Example 1 in Table 1, and the composition of Comparative Example 3 is the same as the composition of Comparative Example 1 in Table 1.
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[Table 2]

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(5) Low friction performance as seen in the LFW-1 boundary friction test
Using an LFW-1 tester, LFW-1 boundary friction tests were performed at a load of 100 lbs, a temperature of 100 ° C., and various sliding speeds.
As is clear from the results in Table 2, the composition of Example 9 (the composition of Example 1 in Table 1) has a lower friction than the composition of Comparative Example 3 (the composition of Comparative Example 1 in Table 1). It can be seen that the characteristics are also excellent. In addition, when the alkaline earth metal salicylate having a low metal ratio is used as the essential component (Examples 5 to 8) as the component (C), it can be seen that extremely excellent low friction performance is exhibited. These compositions exhibit performances equivalent to or higher than those of the composition of Example 9 in terms of base number retention, wear prevention, and high temperature cleanability. The component (C) in Example 6 is a mixture of calcium salicylates having a metal ratio of 1.0 and 2.7, and the metal ratio is 1.46, but the (C) in the composition of Example 5 is It can be seen that the component content can be reduced and that the coefficient of friction is synergistically reduced, particularly in the high slip velocity region. In addition, when tributyl phosphate or triphenyl phosphate is used instead of trioctyl phosphate as the component (A), the low friction performance is superior to that of Comparative Example 3, but trioctyl phosphate has the most excellent low friction performance. Indicated.
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【The invention's effect】
The lubricating oil composition for an internal combustion engine of the present invention has an antioxidant property, even if a sulfur-containing antiwear and antioxidant agent such as ZDTP is reduced or not used at all. Is extremely improved, the base number maintenance property, that is, the long drain performance is extremely excellent, and the high-temperature cleanliness and the low friction property are also obtained.
In addition, since the lubricating oil composition for internal combustion engines of the present invention of the present invention can keep the total sulfur content of the composition low to 0.2% by mass or less, poisoning of the exhaust gas purification catalyst or the like by sulfur And can be suitably used for an engine equipped with an exhaust gas aftertreatment device such as an exhaust gas purification catalyst.
The lubricating oil composition for an internal combustion engine of the present invention is a fuel having a sulfur content of 50 ppm by mass or less, preferably 20 ppm by mass or less, more preferably 10 ppm by mass or less, such as gasoline or LPG. When applied to an engine using natural gas or the like as a fuel, particularly a gas engine, it is possible to further improve the long drain performance and contribute to waste oil problems and resource saving.
Further, the lubricating oil composition for an internal combustion engine of the present invention is a lubricating oil that requires wear prevention, base number maintenance and high temperature cleanliness, for example, a lubricating oil for a drive system such as an automatic or manual transmission, a wet brake, etc. Also, it can be suitably used as lubricating oil such as hydraulic fluid, turbine oil, gear oil, bearing oil and the like.

Claims (7)

In the lubricating base oil, (A) a phosphoric acid triester represented by the general formula (1) is 0.01 to 0.2% by mass in terms of phosphorus element, and (B) succinimide and / or a derivative thereof is nitrogen. 0.01 to 0.3% by mass in terms of element, 0.05 to 1% by mass in terms of metal element (C) alkali metal or alkaline earth metal detergent, and (D) phenolic antioxidant and / or Ri an amine-based antioxidant name contains 0.01 to 3 wt%, the detergent, the table in valency × metal element content of the metal element (mol) / soap group content (mol) A lubricating oil composition for internal combustion engines, which is a salicylate-based detergent having a metal ratio of 3 or less and does not contain zinc dialkyldithiophosphate .
O = P (OR ¹ ) ₃ (1)
(In the formula, R ¹ represents a hydrocarbon group having 1 to 30 carbon atoms, which may be the same or different.) The alkali metal or alkaline earth metal salicylate detergent is a mixture of a salicylate detergent having a metal ratio of 1.5 or less and a salicylate detergent having a metal ratio of more than 1.5. The lubricating oil composition for an internal combustion engine according to claim 1 . The alkali metal or alkaline earth metal salicylate detergent is a salicylate detergent having a metal ratio of 1.5 or less, and further contains an alkali metal or alkaline earth metal sulfonate detergent. Item 2. The lubricating oil composition for internal combustion engines according to Item 1 . 4. The lubricating oil composition for an internal combustion engine according to claim 1, wherein the total sulfur content in the lubricating oil composition is 0.2% by mass or less. The lubricating oil composition for internal combustion engines according to any one of claims 1 to 4, wherein the lubricating base oil has a total aromatic content of 3 mass% or less and a sulfur content of 50 massppm or less. The lubricating oil composition for an internal combustion engine according to any one of claims 1 to 5, wherein the lubricating oil composition is used for an internal combustion engine using a fuel having a sulfur content of 50 ppm by mass or less. The lubricating oil composition for an internal combustion engine according to any one of claims 1 to 6 , wherein the lubricating oil composition is used for a gas engine.