IPC분류정보
국가/구분 |
United States(US) Patent
등록
|
국제특허분류(IPC7판) |
|
출원번호 |
US-0824730
(2004-04-15)
|
등록번호 |
US-7407699
(2008-08-05)
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발명자
/ 주소 |
|
출원인 / 주소 |
|
대리인 / 주소 |
|
인용정보 |
피인용 횟수 :
3 인용 특허 :
31 |
초록
▼
Improved extruded polypropylene sheets containing a high level of beta crystallinity and A process for making such sheets are disclosed herein. The polypropylene sheets comprise a resinous polymer of propylene and an effective amount of beta spherulites. Uniaxially or biaxially oriented mesh struct
Improved extruded polypropylene sheets containing a high level of beta crystallinity and A process for making such sheets are disclosed herein. The polypropylene sheets comprise a resinous polymer of propylene and an effective amount of beta spherulites. Uniaxially or biaxially oriented mesh structures produced from the disclosed sheets exhibit lower density, higher strength, and higher torsional rigidity than polypropylene meshes without beta spherulites. Thus, lighter weight mesh structures which meet all of the physical property requirements for end-use applications, such as reinforcing grids to stabilize concrete and soil in civil engineering and landfill applications, are produced. The lighter weight extruded beta-nucleated sheet can also be stretched at higher line speeds, thereby reducing manufacturing costs.
대표청구항
▼
We claim: 1. An oriented web produced from a perforated extruded sheet comprising a propylene polymer comprising beta-spherulites in an amount sufficient to produce a K-value of about 0.2 to 0.95 when measured by x-ray diffraction or to show a beta crystalline melting peak during the first or secon
We claim: 1. An oriented web produced from a perforated extruded sheet comprising a propylene polymer comprising beta-spherulites in an amount sufficient to produce a K-value of about 0.2 to 0.95 when measured by x-ray diffraction or to show a beta crystalline melting peak during the first or second heating scan when measured using a differential scanning calorimeter, wherein the oriented web is biaxially oriented and wherein the web has thickness in the node junction region between the machine direction and transverse direction strands that is at least 10% less than that of an otherwise identical biaxially oriented web made from a perforated, extruded propylene sheet with no added beta nucleant and the same starting sheet thickness and wherein the oriented web has a tensile strength measured at 2% elongation in the machine direction, that is at least 10% higher than that of an otherwise identical biaxially oriented web made from a perforated, extruded propylene sheet with no added beta nucleant and the same starting thickness. 2. The oriented web of claim 1, wherein the extruded sheet can be run at line speeds that are at least 5% faster than the line speeds for an otherwise identical perforated, extruded propylene sheet with no added beta nucleant and the same starting thickness. 3. The oriented web of claim 1, wherein the oriented web has a tensile strength measured at 5% elongation in the machine direction, that is at least 10% higher than that of an otherwise identical biaxially oriented web made from a perforated, extruded propylene sheet with no added beta nucleant and the same starting thickness. 4. The oriented web of claim 1, wherein the oriented web has a torsional rigidity that is at least 10% higher than that of an otherwise identical biaxially oriented web made from a perforated, extruded propylene sheet with no added beta nucleant and the same starting thickness. 5. The oriented web of claim 1, wherein the beta-spherulites are produced by addition of a beta-nucleating agent having the structural formula: 6. The oriented web of claim 1, wherein the propylene polymer is selected from polypropylene homopolymer and copolymers of polypropylene containing other alpha-olefin monomers. 7. An oriented web produced from a perforated extruded sheet comprising a propylene polymer comprising beta-spherulites in an amount sufficient to produce a K-value of about 0.2 to 0.95 when measured by x-ray diffraction or to show a beta crystalline melting peak during the first or second heating scan when measured using a differential scanning calorimeter, wherein the oriented web is uniaxially oriented and wherein the web has thickness in the node junction region between the machine direction and transverse direction strands that is at least 10% less than that of an otherwise identical uniaxially oriented web made from a perforated, extruded propylene sheet with no added beta nucleant and the same starting sheet thickness and wherein the oriented web has a tensile strength measured at 2% elongation in the machine direction, that is at least 10% higher than that of an otherwise identical uniaxially oriented web made from a perforated, extruded propylene sheet with no added beta nucleant and the same starting thickness. 8. The oriented web of claim 7, wherein the extruded sheet can be run at line speeds that are at least 5% faster than the line speeds for an otherwise identical perforated, extruded propylene sheet with no added beta nucleant and the same starting thickness. 9. The oriented web of claim 7, wherein the oriented web has a tensile strength measured at 5% elongation in the machine direction, that is at least 10% higher than that of an otherwise identical uniaxially oriented web made from a perforated, extruded propylene sheet with no added beta nucleant and the same starting thickness. 10. The oriented web of claim 7, wherein the oriented web has a torsional rigidity that is at least 10% higher than that of an otherwise identical uniaxially oriented web made from a perforated, extruded propylene sheet with no added beta nucleant and the same starting thickness. 11. The oriented web of claim 7, wherein the beta-spherulites are produced by addition of a beta-nucleating agent having the structural formula: 12. The oriented web of claim 7, wherein the propylene polymer is selected from polypropylene homopolymer and copolymers of polypropylene containing other alpha-olefin monomers. 13. A method for making a perforated oriented web, wherein the oriented web is uniaxially oriented or biaxially oriented and wherein the web has thickness in the node junction region between the machine direction and transverse direction strands that is at least 10% less than that of an otherwise identical uniaxially oriented or biaxially oriented web made from a perforated, extruded propylene sheet with no added beta nucleant and the same starting sheet thickness and wherein the oriented web has a tensile strength measured at 2% elongation in the machine direction, that is at least 10% higher than that of an otherwise identical biaxially oriented web made from a perforated, extruded propylene sheet with no added beta nucleant and the same starting thickness, the method comprising the steps of: (a) feeding a concentrate and a resinous propylene polymer to an extruder to melt from a polymeric sheet, wherein the concentrate comprises a propylene resin and a beta-nucleating agent, wherein the beta-nucleating agent is present in a concentration in a range of 1.2% to 0.036% by weight of the total polymer content, (b) quenching the polymeric sheet at a quench temperature sufficient to produce a propylene sheet comprising beta-spherulites in an amount sufficient to produce a K-value of about 0.2 to 0.95 when measured by x-ray diffraction or to show a beta crystalline melting peak during the first or second heating scan when measured using a differential scanning calorimeter, (c) extruding the quenched sheet, (d) perforating the extruded sheet, and (e) orienting the perforated sheet uniaxially or biaxially, wherein the orienting step comprises heating the perforated sheet to a temperature less than or equal to 155�� C. 14. The method of claim 13, wherein step (a) further comprises feeding to the extruder an additive selected from the group consisting of lubricants, antioxidants, ultraviolet absorbers, radiation resistant agents, antiblocking agents, antistatic agents, coloring agents, and opacifiers, which do not nucleate the alpha crystal form of polypropylene. 15. The method of claim 13, wherein step (e) comprises stretching the perforated sheet at a higher drawing rate relative to a drawing rate used to stretch an otherwise identical perforated, extruded propylene sheet with no added beta nucleant and the same starting thickness. 16. The method of claim 13, wherein the beta-nucleating agent has the structural formula: 17. The method of claim 13, wherein the propylene polymer is selected from polypropylene homopolymer and copolymers of polypropylene containing other alpha-olefin monomers. 18. The method of claim 13, wherein the extruded sheet is run at line speeds that are at least 5% faster than the line speeds for an otherwise identical perforated. extruded propylene sheet with no added beta nucleant and the same starting thickness.
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