High molecular weight polyethylene composition, product and process of making same

Abstract

This disclosure relates to a novel type of high molecular weight polyethylene composition, and product made from said composition, with industrially useful properties, and the process of making said composition and product.

Claims

1. A process for preparing an polyethylene product, said process comprising the steps of: (a) providing: i) a first virgin polyethylene resin, having a bimodal molecular weight distribution which is high molecular weight (HMW), having a high load melt index measured according ASTM D-1238 (HLMI) of from about 1 to 6 g/10 min; and comprising a particle size distribution of less than about 50 m; ii) a second virgin polyethylene resin, an HLMI of from about 20-70 g/10 min, a melt flow index measured according ASTM D-1238 (MFI) of from about 0.20-0.60 g/10 min, and comprising a particle size distribution of less than about 50 m; iii) a first post-consumer polyethylene resin, having a MFI of from about 0.10-0.70 g/10 min; iv) a second post-consumer polyethylene resin, which is HMW, and having a HLMI of from about 4-8 g/10 min; and v) a polyethylene antioxidant; (b) blending i) to v) from step (a); and (c) melting and shaping the blend from step (b) to obtain said polyethylene product; wherein said product has at least one property selected from a density of about 0.94-0.96 g/cm.sup.3, a MFI of about 0.05-0.15 g/10 min, a HLMI of about 9-11 gr/10 min, a notched Izod impact factor of >8 ft-lb/in assessed according to ASTM D256, a Flexural Modulus at 2% strain of about 950-1200 Mpa assessed according to ASTM D790 and Tensile Yield of greater than about 25 Mpa assessed according to ASTM D638.

2. The process of claim 1 wherein said product is an extruded film or sheet selected from a blown film, a cast film or an extruded sheet.

3. The process of claim 1, wherein each of said first virgin polyethylene resin, said second virgin polyethylene resin, said first post-consumer polyethylene resin, and said second post-consumer polyethylene resin is a high density polyethylene; wherein said first virgin polyethylene resin, has a density of from about 0.948 to 0.955 g/cm.sup.3, said second virgin polyethylene resin, has a density of from about 0.950 to 0.960 g/cm.sup.3, said first post-consumer polyethylene resin has a_density of from about 0.955 to 0.970 g/cm.sup.3, said second post-consumer polyethylene resin has a density of from about 0.952 to 0.958 g/cm.sup.3.

4. The process of claim 1, wherein said first and second virgin polyethylene resin is each independently comprising a particle size distribution of less than about 30 m.

5. The process of claim 1, wherein a weight ratio of the total of said first and second virgin polyethylene resin: the total of said first and second post-consumer polyethylene resin in the composition is from about 0.8-1.2:1.2-0.8.

6. The process of claim 1, wherein a weight ratio of the first virgin polyethylene resin to the second virgin polyethylene resin is from about 0.8-1.2.

7. The process of claim 1, wherein a weight ratio of the first post-consumer polyethylene resin to the second post-consumer polyethylene resin is from about 0.8-1.2:1.2-0.8.

8. The process of claim 1, wherein a weight ratio of the total of said first and second virgin polyethylene resin to the total of said first and second post-consumer polyethylene resin in the composition is from about 0.8-1.2:1.2-0.8, a weight ratio of the first virgin polyethylene resin to the second virgin polyethylene resin is from about 0.8-1.2 and a weight ratio of the first post-consumer polyethylene resin to the second post-consumer polyethylene resin is from about 0.8-1.2:1.2-0.8.

9. The process of claim 1, wherein said antioxidant is pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 3,5-bis(1,1-dimethylethyl)-4-hydroxy-,2,2-bis[[3-[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]-1-oxopropoxy]methyl]-1,3-propanediyl ester, or 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanoic acid [3-[3-(3,5-ditert-butyl-4-hydroxyphenyl)-1-oxopropoxy]-2,2-bis[[3-(3,5-ditert-butyl-4-hydroxyphenyl)-1-oxopropoxy]methyl]propyl] ester.

10. The process of claim 9, wherein the w/w % amount of antioxidant relative to the total weight of the product is from about 0.5 to 2%.

11. The process of claim 8, wherein said antioxidant is pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 3,5-bis(1,1-dimethylethyl)-4-hydroxy-,2,2-bis[[3-[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]-1-oxopropoxy]methyl]-1,3-propanediyl ester, or 3-(3,5-ditert-butyl-4-hydroxyphenyl)propanoic acid [3-[3-(3,5-ditert-butyl-4-hydroxyphenyl)-1-oxopropoxy]-2,2-bis[[3-(3,5-ditert-butyl-4-hydroxyphenyl)-1-oxopropoxy]methyl]propyl] ester.

12. A polyethylene product comprising a composition comprising: i) a first virgin polyethylene resin, having a bimodal molecular weight distribution which is high molecular weight (HMW), having a high load melt index measured according ASTM D-1238 (HLMI) of from about 1 to 6 g/10 min; and comprising a particle size distribution of less than about 50 m ii) a second virgin polyethylene resin, an HLMI from about 20-70 g/10 min, a melt flow index measured according ASTM D-1238 (MFI) of from about 0.20-0.60 g/10 min, and comprising a particle size distribution of less than about 50 m; iii) a first post-consumer polyethylene resin, having a MFI of from about 0.10-0.70 g/10 min; iv) a second post-consumer polyethylene resin, which is HMW, and having a HLMI of from about 4-8 g/10 min; and v) a polyethylene antioxidant; wherein said product has at least one property selected from a density of about 0.94-0.96 g/cm.sup.3, a MFI of about 0.05-0.15 g/10 min, a HLMI of about 9-11 gr/10 min, a notched Izod impact factor of >8 ft-lb/in assessed according to ASTM D256, a Flexural Modulus at 2% strain of about 950-1200 Mpa assessed according to ASTM D790 and Tensile Yield of greater than about 25 Mpa assessed according to ASTM D638.

13. The product of claim 12, wherein each of said first virgin polyethylene resin, said second virgin polyethylene resin, said first post-consumer polyethylene resin, and said second post-consumer polyethylene resin is a high density polyethylene; wherein said first virgin polyethylene resin, has a density of from about 0.948 to 0.955 g/cm.sup.3, said second virgin polyethylene resin, has a density of from about 0.950 to 0.960 g/cm.sup.3, said first post-consumer polyethylene resin has a density of from about 0.955 to 0.970 g/cm.sup.3, said second post-consumer polyethylene resin has a density of from about 0.952 to 0.958 g/cm.sup.3.

14. The product of claim 12, wherein the w/w % amount of antioxidant relative to the total weight of the product is from about 0.5 to 2%.

15. The product of claim 14, wherein said antioxidant is pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 3,5-bis(1,1-dimethylethyl)-4-hydroxy-,2,2-bis[[3-[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]-1-oxopropoxy]methyl]-1,3-propanediylester, or 3-(3,5-ditert-butyl-4-hydroxyphenyl)propanoic acid [3-[3-(3,5-ditert-butyl-4-hydroxyphenyl)-1-oxopropoxy]-2,2-bis[[3-(3,5-ditert-butyl-4-hydroxyphenyl)-1-oxopropoxy]methyl]propyl] ester.

16. A composition comprising: i) a first virgin polyethylene resin, having a bimodal molecular weight distribution which is high molecular weight (HMW), having a high load melt index measured according ASTM D-1238 (HLMI) of from about 1 to 6 g/10 min; and comprising a particle size distribution of less than about 50 m ii) a second virgin polyethylene resin, an HLMI from about 20-70 g/10 min, a melt flow index measured according ASTM D-1238 (MFI) of from about 0.20-0.60 g/10 min, and comprising a particle size distribution of less than about 50 m; iii) a first post-consumer polyethylene resin, having a MFI of from about 0.10-0.70 g/10 min; iv) a second post-consumer polyethylene resin, which is HMW, and having a HLMI of from about 4-8 g/10 min; and v) a polyethylene antioxidant, wherein the antioxidant is pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 3,5-bis(1,1-dimethylethyl-4-hydroxy-,2,2-bis[[3-[3,5-bis(1,1-dimethylethyl-4-hydroxyphenyl]-1-oxopropoxy]methyl]-1,3-propanediyl ester, or 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanoic acid [3-[3-(3,5-ditert-butyl-4-hydroxphenyl)-1-oxopropoxyl-2,2-bis[[3-(3,5-ditert-butyl-4-hydroxyphenyl)-1-oxopropoxy]methyl]propyl]ester.

Description

EXAMPLES

(1) In operation, the required amount of each component of the composition is measured gravimetrically and discharged into a holding silo. Once all of the components are presented the silo is discharged directly into a rotary drum ribbon blender. The rotary ribbon blades mix the material for a predetermined length of time. Once the composition is mixed, it is sent pneumatically to a crammer silo resident over the throat of an extruder. The composition is then crammed into the throat of a jacketed chill water cooled opening under pressure into an 8 inch 36:1 ratio extruder at temperatures between 225 C. and 290 C. The material flow is screened through a dutch weaved two ply metal screen pack at 88 mesh (150 m). Once molten composition is through the screen it enters a die and is cut into pellets at a 0.125 (31751) diameter. These composition pellets can then be used to manufacture film, extruded sheets, injected parts or other common polyethylene applications.

(2) As used herein, ASTM refers to American Society for Testing and Materials.

(3) The Density is measured according to ASTM D4883 and is defined in g/cm.sup.3.

(4) The High Load Melt Index (HLMI) is measured according to ASTM D1238 using a load 21.6 Kg and is defined in g/10 min.

(5) The Melt Flow Index (MFI) is measured according to ASTM D1238 using a load 2.16 Kg and is defined in g/10 min.

(6) The Izod Impact Notched factor is assessed according to ASTM D256 and reported in kJ/m.sup.2.

(7) The Tensile Yield and Ultimate Break are measured according to ASTM D638 and are respectively defined in MPa and mm.

(8) The Flexural modulus at 2% is measured according to ASTM D790 and is defined in MPa.

(9) The Environmental Stress crack resistance is measured according to ASTM D1693-1 and is rated as a pass % rate.

(10) The Ash content/Filler content ratio is assessed according to ASTM D5630.

(11) The polyethylene content is assessed according to ASTM 3418.

(12) Table 1 summarizes the observations for selected properties based on numerous samples obtained in accordance with the above process.

(13) TABLE-US-00001 TABLE 1 Property Method Value Density (gr/cm.sup.3) ASTM D792 0.949-0.955 Melt Index (gr/10 min) ASTM D1238 0.06-0.11 (190 C./2.16 Kg) High Load melt index (gr/ ASTM D1238 9-11 10 min (190 C./21.6 Kg) Notched Izod impact ASTM D256 >8 No Break Izod (ft-lb/in) >43 (kJ/ m.sup.2) Flexural Modulus at 2% ASTM D790 950-1110 strain (Mpa) Tensile Yield (Mpa) ASTM D638 25 Environmental Stress- ASTM D1693-1 100% Pass Cracking of ethylene plastics Ash content/Filler content ASTM D5630 0.376% DSC (Melting Point) 0.70-0.90 PE content ASTM 3418 130-135 c. >99.5% PE

(14) As can be understood, the examples described above and illustrated are intended to be exemplary only. The scope is indicated by the appended claims.

(15) All references cited herein are incorporated herein by reference.