We claim:
1. A method for maintaining low temperature fluidity of a lubricating oil composition comprising adding from 0.03 to 3 percent, based on total lubricating oil composition weight, of a first P1 and a second P2 polymer to the lubricating oil composition wherein:
(a) the first polymer P1 comprises zero to 15 percent monomer units selected from one or more (C1-C6)alkyl (meth)acrylates, 30 to 75 percent monomer units selected from one or more (C7-C15)alkyl (meth)acrylates and 25 to 70 percent monomer units selected from one or more (C16-C24)alkyl (meth)acrylates, based on total first polymer weight, and has a weight average molecular weight from 250,000 to 1,500,000;
(b) the second polymer P2 comprises zero to 15 percent monomer units selected from one or more (C1-C6)alkyl (meth)acrylates, 75 to 100 percent monomer units selected from one or more (C7-C15)alkyl (meth)acrylates and zero to 25 percent monomer units selected from one or more (C16-C24)alkyl (meth)acrylates, based on total second polymer weight, and has a weight average molecular weight from 10,000 to 1,500,000;
(c) the first polymer P1 has a weight average molecular weight at least 50,000 greater than that of the second polymer P2; and
(d) the first and second polymers are combined in a weight ratio (P1P2) of 595 to 7525.
2. The method of claim 1 wherein the first P1 and second P2 polymers are selected and combined in a weight ratio such that the lubricating oil composition has:
(a) a gel index of less than 12, and
(b) a low-shear rate viscosity of less than 60 pascalseconds with a yield stress of less than 35 pascals.
3. The method of claim 2 wherein the gel index is less than 8.5 and the low-shear rate viscosity is less than 55 pascalseconds.
4. The method of claim 1 wherein the first polymer P1 has a weight average molecular weight from 300,000 to 800,000, and the second polymer P2 has a weight average molecular weight from 20,000 to 200,000.
5. The method of claim 1 wherein:
(a) the first polymer P1 comprises 35 to less than 70 percent monomer units selected from one or more (C7-C15)alkyl (meth)acrylates and greater than 30 up to 65 percent monomer units selected from one or more (C16-C24)alkyl (meth)acrylates; and
(b) the second polymer P2 comprises 85 to 95 percent monomer units selected from one or more (C7-C15)alkyl (meth)acrylates and 5 to 15 percent monomer units selected from one or more (C16-C24)alkyl (meth)acrylates.
6. The method of claim 1 wherein the (C7-C15)alkyl (meth)acrylate of the first P1 and second polymer P2 is selected from one or more of isodecyl methacrylate, dodecyl-pentadecyl methacrylate, nonyl-undecyl methacrylate and lauryl-myristyl methacrylate; and the (C16-C24)alkyl (meth)acrylate of the first P1 and second polymer P2 is selected from one or more of cetyl-eicosyl methacrylate and cetyl-stearyl methacrylate.
7. A method for maintaining low temperature fluidity of a lubricating oil composition comprising adding from 0.03 to 3 percent, based on total lubricating oil composition weight, of a first P1 and a second P2 polymer to the lubricating oil composition wherein:
(a) the first polymer P1 comprises monomer units selected from one or more of vinylaromatic monomers, -olefins, vinyl alcohol esters, (meth)acrylic acid derivatives, maleic acid derivatives and fumaric acid derivatives, and has a weight average molecular weight from 250,000 to 1,500,000;
(b) the second polymer P2 comprises monomer units selected from one or more of vinylaromatic monomers, -olefins, vinyl alcohol esters, (meth)acrylic acid derivatives, maleic acid derivatives and fumaric acid derivatives, and has a weight average molecular weight from 10,000 to 1,500,000;
(c) the first polymer P1 has a weight average molecular weight at least 50,000 greater than that of the second polymer P2; and
(d) the first and second polymers are combined in a weight ratio (P1P2) of 595 to 7525.
8. The method of claim 7 wherein the first P1 and second P2 polymers are selected from one or more of vinylaromatic-(meth)acrylic acid derivative copolymers, vinylaromatic-maleic acid derivative copolymers, vinyl alcohol ester-fumaric acid derivative copolymers, -olefin-vinyl alcohol ester copolymers, -olefin-maleic acid derivative copolymers and -olefin-fumaric acid derivative copolymers.
9. A concentrate for use in lubricating oil compositions comprising a lubricating oil diluent and from 30 to 70 percent, based on weight of the concentrate, of a first P1 and a second P2 polymer, wherein:
(a) the first polymer P1 comprises zero to 15 percent monomer units selected from one or more (C1-C6)alkyl (meth)acrylates, 30 to 75 percent monomer units selected from one or more (C7-C15)alkyl (meth)acrylates and 25 to 70 percent monomer units, selected from one or more (C16-C24)alkyl (meth)acrylates, based on total first polymer weight, and has a weight average molecular weight from 250,000 to 1,500,000;
(b) the second polymer P2 comprises zero to 15 percent monomer units selected from one or more (C1-C6)alkyl (meth)acrylates, 90 to 100 percent monomer units selected from one or more (C7-C15)alkyl (meth)acrylates and zero to 10 percent monomer units selected from one or more (C16-C24)alkyl (meth)acrylates, based on total second polymer weight, and has a weight average molecular weight from 10,000 to 1,500,000;
(c) the first polymer P1 has a weight average molecular weight at least 50,000 greater than that of the second polymer P2; and
(d) the first and second polymers are combined in a weight ratio (P1P2) of 595 to 7525.
10. A lubricating oil composition comprising a lubricating oil and from 0.03 to 3 per cent, based on weight of the lubricating oil composition, of a first P1 and a second P2 polymer wherein:
(a) the first polymer P1 comprises zero to 15 percent monomer units selected from one or more (C1-C6)alkyl (meth)acrylates, 30 to 75 percent monomer units selected from one or more (C7-C15)alkyl (meth)acrylates and 25 to 70 percent monomer units, selected from one or more (C16-C24)alkyl (meth)acrylates, based on total first polymer weight, and has a weight average molecular weight from 250,000 to 1,500,000;
(b) the second polymer P2 comprises zero to 15 percent monomer units selected from one or more (C1-C6)alkyl (meth)acrylates, 90 to 100 percent monomer units selected from one or more (C7-C15)alkyl (meth)acrylates and zero to 10 percent monomer units selected from one or more (C16-C24)alkyl (meth)acrylates, based on total second polymer weight, and has a weight average molecular weight from 10,000 to 1,500,000;
(c) the first polymer P1 has a weight average molecular weight at least 50,000 greater than that of the second polymer P2;
(d) the first and second polymers are combined in a weight ratio (P1P2) of 595 to 7525;
(e) the lubricating oil comprises a base fluid selected from one or more of API Group I and Group II base stocks; and
(f) the lubricating oil composition comprises from 0.1 to 20 percent, based on total lubricating oil composition weight, of auxiliary additives selected from one or more viscosity index improvers, antiwear agents, antioxidants, dispersants, detergents, friction modifiers, antifoam agents, extreme pressure additives and corrosion inhibitors.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A flexure supporting a head to read and write data, comprising:
a metal substrate;
an insulating layer formed on the metal substrate;
a wiring pattern arranged on the insulating layer and having a first end connected to the head and a second end that is provided with a terminal for external connection;
the insulating layer extending a back of the terminal and a surrounding portion of the back; and
the metal substrate having an isolated portion that is on the back of the terminal through the insulating layer and is separated and electrically isolated from the other portion of the metal substrate.
2. The flexure of claim 1 wherein the isolated portion has a planar shape so as to cover the terminal entirely.
3. The flexure of claim 2 wherein the isolated portion has a planar shape larger than the terminal.
4. The flexure of claim 1 wherein the isolated portion is rectangular, decussate or circular in a planar shape.
5. The flexure of claim 1, further comprising:
a through hole formed through the isolated portion.
6. The flexure of claim 1 wherein the isolated portion is separated from the other portion with a gap of at least 70 \u03bcm.
7. The flexure of claim 1, further comprising:
a passage formed through the insulating layer over the isolated portion;
a connection passing through the passage and electrically connecting the isolated portion and the terminal.
8. The flexure of claim 7 wherein the passage is formed through the terminal along with the insulating layer and the connection is formed from a conductive material filling the passage.
9. The flexure of claim 7 wherein the connection is integrated with and extends from the terminal.
10. The flexure of claim 1 wherein the wiring pattern includes plural traces each having the terminal and the isolated portion is formed on the back of each terminal through the insulating layer.
11. A head suspension with the flexure of claim 1, comprising:
a base plate and a load beam supported with the base plate;
the flexure attached to the load beam.