Durable polyoxymethylene composition

{
  "publication_number": "US2011237727A1",
  "country": "US",
  "kind": "A1",
  "title": "Durable polyoxymethylene composition",
  "abstract": "A durable polyoxymethylene composition and a ramp made of the durable polyoxymethylene composition are disclosed. The durable polyoxymethylene composition of the present invention has excellent micro-wear-resistant property.",
  "claims": [
    "1. A polyoxymethylene composition, which has at least one of the micro-wear loss of less than 1 μm maximum wear depth or less than 10 μm 2 wear area under a condition of a load of 2.5 g after being reciprocated 600,000 times at a speed of 8 inch/second and an environmental humidity of 13% to 17% RH and an environmental temperature of 3° C. to 10° C., the polyoxymethylene composition comprising: a polyoxymethylene copolymer of 90.5 wt % to 92.5 wt % including 3.3 wt % of 1,3-dioxolane as a comonomer; an inorganic filler of 0.5 wt % to 3.0 wt %; a lubricant of 3.0 wt % to 10.0 wt %; a nucleating agent of 1.0 wt % to 3.0 wt %; a stabilizer of 0.5 wt % to 1.0 wt %; and an anti-static agent of 0.5 wt % to 2.0 wt %. 2. The polyoxymethylene composition of claim 1, wherein said lubricant is a modified polyolefin. 3. The polyoxymethylene composition of claim 2, wherein the modified polyolefin comprises a maleic anhydride modified polyolefin. 4. The polyoxymethylene composition of claim 1, wherein said inorganic filler comprises nano-grade zinc oxide particles with an average particle size not greater than 100 nm. 5. The polyoxymethylene composition of claim 1, wherein the nucleating agent comprises at least one of a sodium salt of montanic acid and a long chain, linear carboxylic acid. 6. The polyoxymethylene composition of claim 1, wherein the stabilizer comprises at least one of an antioxidant and an acid scavenger. 7. The polyoxymethylene composition of claim 1, wherein the anti-static agent comprises a glycerol monostearate. 8. The polyoxymethylene composition of claim 1 further comprising an ultra high molecular weight polyethylene having a molecular weight of 2 million with an average particle size of 30 μm in a range of 3 wt % to 10 wt %. 9. The polyoxymethylene composition of claim 1 further comprising: potassium titanate powder having an average particle size of 1.5 μm in a range of 0.5 wt % to 1.0 wt %. 10. The polyoxymethylene composition of claim 1 further comprising: calcium carbonate having a volume average particle diameter of 1 μm in a range of 0.5 wt % to 2.0 wt %. 11. The polyoxymethylene composition of claim 1 further comprising: nano-grade silca dioxide with an average particle size of 20 nm in a range of 0.5 wt % to 2 wt %. 12. The polyoxymethylene composition of claim 1 further comprising: titanium dioxide with an average particle size of 1 μm in a range of 0.5 wt % to 2 wt %. 13. The polyoxymethylene composition of claim 1 further comprising: a low density polyethylene of (5%) with a melt flow rate 28 g/10 min. 14. A ramp which has at least one of the micro-wear loss of less than 1 μm maximum wear depth and of less than 10 μm 2 wear area under a condition of a load of 2.5 g after being reciprocated 600,000 times at a speed of 8 inch/sec and an environmental humidity of 13% to 17% RH) and an environmental temperature of 3° C. to 10° C., the ramp comprising: a polyoxymethylene copolymer of 90.5 wt % to 92.5 wt % including 3.3 wt % of 1,3-dioxolane as a comonomer; an inorganic filler of 1.0 wt % to 3.0 wt %; a lubricant of 3.0 wt % to 10.0 wt %; a nucleating agent of 1.0 wt % to 3.0 wt %; a stabilizer of 0.5 wt % to 1.0 wt %; and an anti-static agent of 0.5 wt % to 2.0 wt %. 15. A micro-wear-resistant polyoxymethylene composition which has at least one of the micro-wear loss of less than 0.5 μm maximum wear depth and of less than 5 μm 2 wear area under a condition of a load of 2.5 g after being reciprocated 600,000 times at a speed of 8 inch/sec and an environmental humidity of 50% to 60% RH and an environmental temperature of 22° C. to 60° C., the micro-wear-resistant polyoxymethylene composition comprising: a polyoxymethylene copolymer of 90.5 wt % to 92.5 wt % including 3.3 wt % of 1,3-dioxolane as a comonomer; an inorganic filler of 0.5 wt % to 3.0 wt %; a lubricant of 3.0 wt % to 10.0 wt %; a nucleating agent of 1.0 wt % to 3.0 wt %; a stabilizer of 0.5 wt % to 1.0 wt %; and an anti-static agent of 0.5 wt % to 2.0 wt %. 16. The polyoxymethylene composition of claim 15, wherein said lubricant is a modified polyolefin. 17. The polyoxymethylene composition of claim 16, wherein the modified polyolefin comprises a maleic anhydride modified polyolefin. 18. The polyoxymethylene composition of claim 15, wherein said inorganic filler is nano-grade zinc oxide particles with an average particle size not greater than 100 nm. 19. The polyoxymethylene composition of claim 15, wherein the nucleating agent comprises at least one of a sodium salt of montanic acid and a long chain, linear carboxylic acid. 20. The polyoxymethylene composition of claim 15, wherein the stabilizer comprises at least one of an antioxidant and an acid scavenger. 21. The polyoxymethylene composition of claim 15, wherein the anti-static agent comprises a glycerol monostearate. 22. The polyoxymethylene composition of claim 15, further comprising: an ultra high molecular weight polyethylene of molecular weight 2 million with average particle size 30 μm in a range of 3 wt % to 10 wt %. 23. The polyoxymethylene composition of claim 15, further comprising: potassium titanate powder having an average particle size of 1.5 μm in a range of 0.5 wt % to 1.0 wt %. 24. The polyoxymethylene composition of claim 15, further comprising: calcium carbonate having a volume average particle diameter of 1 μm in a range of 0.5 wt % to 2.0 wt %. 25. The polyoxymethylene composition of claim 15, further comprising: nano-grade silca dioxide with an average particle size of 20 nm in a range of 0.5 wt % to 2 wt %. 26. The polyoxymethylene composition of claim 15, further comprising: titanium dioxide with an average particle size of 1 μm in a range of 0.5 wt % to 2.0 wt %. 27. The polyoxymethylene composition of claim 15, further comprising: a low density polyethylene with a melt flow rate 28 g/10 min. 28. A ramp which has at least one of the micro-wear loss of less than 0.5 μm maximum wear depth and of less than 5 μm 2 wear area under a condition of a load of 2.5 g after being reciprocated 600,000 times at a speed of 8 inch/sec and an environmental humidity of 50%-60% RH and an environmental temperature of 22° C. to 60° C., the ramp comprising: a polyoxymethylene copolymer of 90.5 wt % to 92.5 wt % including 3.3 wt % of 1,3-dioxolane as a comonomer; an inorganic filler of 0.5 wt % to 3.0 wt %; a lubricant of 3.0 wt % to 10.0 wt %; a nucleating agent of 1.0 wt % to 3.0 wt %; a stabilizer of 0.5 wt % to 1.0 wt %; and an anti-static agent of 0.5 wt % to 2.0 wt %."
  ],
  "description_excerpt": "1. Field of the Invention\n\nThe present invention generally relates to a durable polyoxymethylene composition and a ramp including a durable polyoxymethylene composition. In particular, the present invention is directed to a durable polyoxymethylene composition as well as a ramp including a durable polyoxymethylene composition with excellent micro-wear-resistant property under a high humidity and high temperature condition, or under a low humidity and low temperature condition.\n\n2. Description of the Prior Art\n\nA polyoxymethylene resin is a widely used engineering resin due to its well-balanced mechanical properties, remarkable chemical resistance and sliding properties as well as the good friction wear performance. Recently, attempts have been made to use such polyoxymethylene resin as material for a ramp in a hard disk drive. For example, US 2008/0037175 discloses a ramp including a polyoxymethylene resin and a colorant for a hard disk drive. The ramp has an outgas level of 20 μg/g or less. U.S. Pat. No. 7,088,555 discloses a ramp having a surface hardness of 2.6 GPa or more.\n\nHowever, in the aforementioned conventional technologies, no description is yet made to a polyoxymethylene resin with excellent micro-wear-resistant properties, and further, no proposal for attempting to reduce wear debris from a polyoxymethylene resin ramp is found.\n\nThe present invention has the properties of micro-wear resistance, high mechanical stability and high moldability.",
  "cpc": [
    "C08L 59/00",
    "C08K 3/013",
    "C08K 5/0016",
    "C08K 5/005",
    "C08K 5/0075",
    "C08K 5/0083"
  ],
  "ipc": [
    "C08J 3/20",
    "C08K 3/00",
    "C08K 3/10",
    "C08K 3/22",
    "C08K 3/26",
    "C08K 3/36",
    "C08K 5/09",
    "C08K 5/103"
  ],
  "assignees": [
    "MIN AIK Tech CO Ltd"
  ],
  "inventors": [
    "Jung-Pao Chang",
    "Chi-En Lin"
  ],
  "filing_date": "2010-06-22",
  "publication_date": "2011-09-29",
  "priority_date": "2010-03-29",
  "application_number": "US-82014510-A",
  "family_id": "44278689",
  "cited_by_count": 8,
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}