Magnetic recording disk and method for manufacture thereof

A magnetic recording disk comprising a nonmagnetic substrate on which at least a magnetic layer, a protective layer, and a lubricating layer are arranged in that order,

• wherein the lubricating layer is made from a lubricant;
• the lubricant contains principal components which are perfluoropolyether compounds represented by the following chemical formula (Chemical Formula 2) and which are a first component having terminal groups X represented by X1, a second component having terminal groups X represented by X2, and a third component having terminal groups X represented by X3;
• and the sum of the content of the first component, that of the second component, and that of the third component in the perfluoropolyether compounds is 99.0% or more on a molar basis in the case where the lubricant is analyzed by nuclear magnetic resonance spectroscopy:
• X—OCH2CF2—(CF2O)m(C2F4O)n—CF2OCH2O—X (Chemical Formula 2)
• m, n=9 to 11
• first component:
• X=X1=CH2CH(OH)CH2OH
• second component:
• X=X2=CH2CH(OH)CH2OCH2CH(OH)CH2OH
• third component:
• X=X3=H.

A magnetic recording disk comprising a nonmagnetic substrate on which at least a magnetic layer, a protective layer, and a lubricating layer are arranged in that order,

• wherein the lubricating layer is made from a lubricant;
• the lubricant contains principal components which are perfluoropolyether compounds represented by the following chemical formula (Chemical Formula 3) and which are a first component having terminal groups X represented by X1, a second component having terminal groups X represented by X2, a third component having terminal groups X represented by X3, a fourth component having terminal groups X represented by X4, and a fifth component having terminal groups X represented by X5;
• and the sum of the content of the fourth component and that of the fifth component in the perfluoropolyether compounds is 1.0% or less on a molar basis in the case where the lubricant is analyzed by nuclear magnetic resonance spectroscopy:
• X—OCH2CF2—(CF2O)m(C2F4O)n—CF2OCH2O—X (Chemical Formula 3)
• m, n=9 to 11
• first component:
• X=X1=CH2CH(OH)CH2OH
• second component:
• X=X2=CH2CH(OH)CH2OCH2CH(OH)CH2OH
• third component:
• X=X3=H
• fourth component:
• X=X4=CF3
• fifth component:
• X=X5=CF2Cl.

A magnetic recording disk comprising a nonmagnetic substrate on which at least a magnetic layer, a protective layer, and a lubricating layer are arranged in that order,

• wherein the lubricating layer is made from a lubricant;
• the lubricant contains principal components which are perfluoropolyether compounds represented by the following chemical formula (Chemical Formula 4) and which are a first component having terminal groups X represented by X1, a second component having terminal groups X represented by X2, a third component having terminal groups X represented by X3, a fourth component having terminal groups X represented by X4, and a fifth component having terminal groups X represented by X5;
• and the content of the fourth component is less than that of the fifth component in the case where the lubricant is analyzed by nuclear magnetic resonance spectroscopy:
• X—OCH2CF2—(CF2O)m(C2F4O)n—CF2OCH2O—X (Chemical Formula 4)
• m, n=9 to 11
• first component:
• X=X1=CH2CH(OH)CH2OH
• second component:
• X=X2=CH2CH(OH)CH2OCH2CH(OH)CH2OH
• third component:
• X=X3=H
• fourth component:
• X=X4=CF3
• fifth component:
• X=X5=CF2Cl.