GB2152515A - Blends of LLDPE, LDPE and PP for films having improved stiffness and good optical properties - Google Patents

Blends of LLDPE, LDPE and PP for films having improved stiffness and good optical properties Download PDF

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Publication number
GB2152515A
GB2152515A GB08432810A GB8432810A GB2152515A GB 2152515 A GB2152515 A GB 2152515A GB 08432810 A GB08432810 A GB 08432810A GB 8432810 A GB8432810 A GB 8432810A GB 2152515 A GB2152515 A GB 2152515A
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GB
United Kingdom
Prior art keywords
lldpe
ldpe
weight percent
blends
low density
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
GB08432810A
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GB8432810D0 (en
Inventor
Surinder Kuman Bahl
Peter J Canterino
Richard Gregg Shaw
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
ExxonMobil Oil Corp
Original Assignee
Mobil Oil Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Mobil Oil Corp filed Critical Mobil Oil Corp
Publication of GB8432810D0 publication Critical patent/GB8432810D0/en
Publication of GB2152515A publication Critical patent/GB2152515A/en
Withdrawn legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
    • C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
    • C08L23/04—Homopolymers or copolymers of ethene
    • C08L23/08—Copolymers of ethene
    • C08L23/0807—Copolymers of ethene with unsaturated hydrocarbons only containing more than three carbon atoms
    • C08L23/0815—Copolymers of ethene with aliphatic 1-olefins
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L2205/00—Polymer mixtures characterised by other features
    • C08L2205/03—Polymer mixtures characterised by other features containing three or more polymers in a blend
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
    • C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
    • C08L23/04—Homopolymers or copolymers of ethene
    • C08L23/06—Polyethene
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
    • C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
    • C08L23/10—Homopolymers or copolymers of propene
    • C08L23/12—Polypropene

Abstract

The improved haze and gloss obtained by blending a minor proportion of low density polyethylene (LDPE) with a major proportion of linear low density polyethylene (LLDPE) are substantially retained, and the stiffness is significantly improved, by adding a small amount (5-15 weight percent) of polypropylene (PP). The blends are suitable for use in films.

Description

SPECIFICATION Blends of LLDPE, LDPE and PP for films having improved stiffness and good optical properties Blends of linear low density (LLDPE) conventional low density polyethylene (LDPE) which exhibit markedly improved optical properties when compared to the original optical properties of the blend components are known in the art, for instance from US-A-3,176,052. The secant modulus (stiffness) of the blends is generally less than that of the LLDPE component. We have now discovered that the modulus of these LLDPE/LDPE blends can be increased without significant loss of optical properties by the addition of a small amount of polypropylene (PP).
This invention relates to thermoplastic polymer blends comprising linear low density polyethylene (LLDPE), high pressure low density polyethylene (LDPE) and sufficient polypropylene (PP) to improve the stiffness (modulus) of the LLDPE by at least 10 percent.
The thermoplastic blends of this invention generally comprise at least 50 weight percent of a low density copolymer of ethylene and a higher olefin having 4to 10 carbon atoms (LLDPE); 10 to 45 weight percent of high pressure low density polyethylene; and 2 to 15 weight percent of polypropylene (PP).
The amount of polypropylene is selected to achieve the desired stiffness (modulus) and the amount can vary somewhat depending on the alpha-olefin comonomer used to prepare the LLDPE, the melt index of the LLDPE and other factors.
Similarly, the amount of LDPE is selected to achieve the desired improvement in optical properties and can vary depending on the nature of the LLDPE and the proportion of PP.
Preferred compositions comprise 60 to 70 weight percent of LLDPE; 5 to 10 weight percent PP; and 30 to 40 weight percent of LDPE.
The blends of this invention can be physical blends of pellets of the separate ingredients or melt blends.
The blends in either case are intended for ultimate formation into articles such as films having the improved stiffness and clarity which we have discovered.
The term linear low density polyethylene (LLDPE) as used herein refers to copolymers of ethylene and an alpha-olefin having 4 to 10 carbon atoms. Representative alpha-olefins include butene, hexene and octene.
Generally, the LLDPE contains up to about 10 weight percent of polymerized alpha-olefin, has a density of 0.9 to 0.94 and a melt index of 0.2 to 10. The preparation of LLDPE is described in US-A-4,076,698. LLDPE is also commercially available.
The polypropylene (PP) referred to herein includes any of the known homopolymers and polymers of this class, as well as ethylene-propylene copolymers having a high propylene content which is generally above 90 weight percent. Ethylene-propylene copolymers with a propylene content of about 97 weight have been found to be suitable, many of which are commercially available. The polypropylene homopolymer or copolymer is selected for its ability to impart stiffness to the blend as shown by increased secant modulus.
Accordingly, ethylene-propylene copolymers having a sufficient propylene content to impart the desired stiffness are useful in this invention.
The invention is illustrated by the following non-limiting example in which all parts are by weight unless otherwise specified.
Example A film (1.5 mil.) was prepared from a blend of 68/24/8 weight percent of LLDPE/LDPE/PP and its secant modulus (stiffness), haze and gloss are compared to a 1.5 mil. LLDPE film in the Table below.
TABLE Secant Modulus (in. Is q. in.) Haze Gloss Type (MD) (TD) Percent Percent LLDPE 27400 27600 14.2 40 LLDPE/LDPE/PP 41100 41700 5.1 75
CLAIMS 1. Athermoplastic blend comprising: at least 50 weight percent of a linear low density copolymer of ethylene and a higher olefin having 4 to 10 carbon atoms (LLDPE); 10 to 45 weight percent of high pressure low density polyethylene (LDPE); and 2 to 15 weight percent of polypropylene (PP) or ethylene-propylene copolymer having a high propylene content.
2. The thermoplastic blend of claim 1 in which said LLDPE copolymer comprises ethylene and butene.
3. The thermoplastic blend of claim 1 in which said LLDPE copolymer comprises ethylene and octene.
**WARNING** end of DESC field may overlap start of CLMS **.

Claims (10)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Blends of LLDPE, LDPE and PP for films having improved stiffness and good optical properties Blends of linear low density (LLDPE) conventional low density polyethylene (LDPE) which exhibit markedly improved optical properties when compared to the original optical properties of the blend components are known in the art, for instance from US-A-3,176,052. The secant modulus (stiffness) of the blends is generally less than that of the LLDPE component. We have now discovered that the modulus of these LLDPE/LDPE blends can be increased without significant loss of optical properties by the addition of a small amount of polypropylene (PP). This invention relates to thermoplastic polymer blends comprising linear low density polyethylene (LLDPE), high pressure low density polyethylene (LDPE) and sufficient polypropylene (PP) to improve the stiffness (modulus) of the LLDPE by at least 10 percent. The thermoplastic blends of this invention generally comprise at least 50 weight percent of a low density copolymer of ethylene and a higher olefin having 4to 10 carbon atoms (LLDPE); 10 to 45 weight percent of high pressure low density polyethylene; and 2 to 15 weight percent of polypropylene (PP). The amount of polypropylene is selected to achieve the desired stiffness (modulus) and the amount can vary somewhat depending on the alpha-olefin comonomer used to prepare the LLDPE, the melt index of the LLDPE and other factors. Similarly, the amount of LDPE is selected to achieve the desired improvement in optical properties and can vary depending on the nature of the LLDPE and the proportion of PP. Preferred compositions comprise 60 to 70 weight percent of LLDPE; 5 to 10 weight percent PP; and 30 to 40 weight percent of LDPE. The blends of this invention can be physical blends of pellets of the separate ingredients or melt blends. The blends in either case are intended for ultimate formation into articles such as films having the improved stiffness and clarity which we have discovered. The term linear low density polyethylene (LLDPE) as used herein refers to copolymers of ethylene and an alpha-olefin having 4 to 10 carbon atoms. Representative alpha-olefins include butene, hexene and octene. Generally, the LLDPE contains up to about 10 weight percent of polymerized alpha-olefin, has a density of 0.9 to 0.94 and a melt index of 0.2 to 10. The preparation of LLDPE is described in US-A-4,076,698. LLDPE is also commercially available. The polypropylene (PP) referred to herein includes any of the known homopolymers and polymers of this class, as well as ethylene-propylene copolymers having a high propylene content which is generally above 90 weight percent. Ethylene-propylene copolymers with a propylene content of about 97 weight have been found to be suitable, many of which are commercially available. The polypropylene homopolymer or copolymer is selected for its ability to impart stiffness to the blend as shown by increased secant modulus. Accordingly, ethylene-propylene copolymers having a sufficient propylene content to impart the desired stiffness are useful in this invention. The invention is illustrated by the following non-limiting example in which all parts are by weight unless otherwise specified. Example A film (1.5 mil.) was prepared from a blend of 68/24/8 weight percent of LLDPE/LDPE/PP and its secant modulus (stiffness), haze and gloss are compared to a 1.5 mil. LLDPE film in the Table below. TABLE Secant Modulus (in. Is q. in.) Haze Gloss Type (MD) (TD) Percent Percent LLDPE 27400 27600 14.2 40 LLDPE/LDPE/PP 41100 41700 5.1 75 CLAIMS
1. Athermoplastic blend comprising: at least 50 weight percent of a linear low density copolymer of ethylene and a higher olefin having 4 to 10 carbon atoms (LLDPE); 10 to 45 weight percent of high pressure low density polyethylene (LDPE); and 2 to 15 weight percent of polypropylene (PP) or ethylene-propylene copolymer having a high propylene content.
2. The thermoplastic blend of claim 1 in which said LLDPE copolymer comprises ethylene and butene.
3. The thermoplastic blend of claim 1 in which said LLDPE copolymer comprises ethylene and octene.
4. The thermoplastic blend of claim 1 in which said LLDPE copolymer comprises ethylene and hexene.
5. The thermoplastic blend of claim 1 comprising: 60 to 70 weight percent of LLDPE: 30 to 40 weight percent LDPE; and 5 to 10 weight percent PP.
6. A thermoplastic blend comprising a linear low density coplymer of ethylene and a higher olefin having 4 to 10 carbon atoms (LLDPE), high pressure low density polyethylene (LDPE), the LLDPE being present in a greater amount than the LDPE, and polypropylene or ethylenepropylene copolymer having a high propylene content in an amount sufficient to increase the modulus of the blend of LLDPE and LDPE by at least 10 percent.
7. The thermoplastic blend of claim 6 in which said LLDPE copolymer comprises ethylene and butene.
8. The thermoplastic blend of claim 6 in which said LLDPE copolymer comprises ethylene and octene.
9. The thermoplastic blend of claim 6 in which said LLDPE copolymer comprises ethylene and hexene.
10. The thermoplastic blend of any preceding claim in the form of a film.
GB08432810A 1984-01-04 1984-12-31 Blends of LLDPE, LDPE and PP for films having improved stiffness and good optical properties Withdrawn GB2152515A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US56799584A 1984-01-04 1984-01-04

Publications (2)

Publication Number Publication Date
GB8432810D0 GB8432810D0 (en) 1985-02-06
GB2152515A true GB2152515A (en) 1985-08-07

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Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0238756A2 (en) * 1985-12-30 1987-09-30 Mobil Oil Corporation Blends of linear low density polyethylene, polypropylene and aromatic polymers and high modulus films thereof
EP0241234A2 (en) * 1986-04-03 1987-10-14 Exxon Chemical Patents Inc. Diaper backsheet
EP0253792A2 (en) * 1986-06-13 1988-01-20 Monsanto Company Film composition
EP0256885A2 (en) * 1986-08-20 1988-02-24 Tredegar Industries, Inc. Refastenable diapers and sheets therefor
EP0688820A1 (en) * 1994-06-20 1995-12-27 Montell North America Inc. Linear low density polyethylene based compositions with improved optics
EP0687558A3 (en) * 1994-05-19 1996-03-13 Viskase Corp Polyolefin stretch film
WO1997018083A1 (en) * 1995-11-14 1997-05-22 Montell Technology Company B.V. Lldpe-based stretchable multilayer films
US8163216B2 (en) 2005-04-26 2012-04-24 Rkw Se Method for producing a film web
CN107815016A (en) * 2017-10-31 2018-03-20 遵义宏龙塑料有限责任公司 A kind of preparation method of novel plastic woven bag
AU2020103984B4 (en) * 2016-01-22 2021-10-14 System Stormseal Pty Ltd Heat shrink covering of built structures and method
US11827774B2 (en) * 2017-12-18 2023-11-28 Borealis Ag Polymer blend composition for wire and cable applications with advantageous electrical properties

Cited By (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0238756A2 (en) * 1985-12-30 1987-09-30 Mobil Oil Corporation Blends of linear low density polyethylene, polypropylene and aromatic polymers and high modulus films thereof
EP0238756A3 (en) * 1985-12-30 1989-12-06 Mobil Oil Corporation Blends of linear low density polyethylene, polypropylene and aromatic polymers and high modulus films thereof
EP0241234A2 (en) * 1986-04-03 1987-10-14 Exxon Chemical Patents Inc. Diaper backsheet
EP0241234A3 (en) * 1986-04-03 1989-07-26 Exxon Chemical Patents Inc. Diaper backsheet
EP0253792A2 (en) * 1986-06-13 1988-01-20 Monsanto Company Film composition
EP0253792A3 (en) * 1986-06-13 1989-04-26 Monsanto Company Film composition
EP0256885A2 (en) * 1986-08-20 1988-02-24 Tredegar Industries, Inc. Refastenable diapers and sheets therefor
EP0256885A3 (en) * 1986-08-20 1989-04-26 Ethyl Corporation Refastenable diapers and sheets therefor
US5614297A (en) * 1994-05-19 1997-03-25 Viskase Corporation Polyolefin stretch film
EP0687558A3 (en) * 1994-05-19 1996-03-13 Viskase Corp Polyolefin stretch film
EP0872337A1 (en) * 1994-05-19 1998-10-21 Viskase Corporation Polyolefin stretch film
EP0875373A1 (en) * 1994-05-19 1998-11-04 Viskase Corporation Polyolefin stretch film
EP0875372A1 (en) * 1994-05-19 1998-11-04 Viskase Corporation Polyolefin stretch film
EP0688820A1 (en) * 1994-06-20 1995-12-27 Montell North America Inc. Linear low density polyethylene based compositions with improved optics
AU689876B2 (en) * 1994-06-20 1998-04-09 Montell North America Inc. Linear low density polyethylene based compositions with improved optics
WO1997018083A1 (en) * 1995-11-14 1997-05-22 Montell Technology Company B.V. Lldpe-based stretchable multilayer films
US8163216B2 (en) 2005-04-26 2012-04-24 Rkw Se Method for producing a film web
AU2020103984B4 (en) * 2016-01-22 2021-10-14 System Stormseal Pty Ltd Heat shrink covering of built structures and method
CN107815016A (en) * 2017-10-31 2018-03-20 遵义宏龙塑料有限责任公司 A kind of preparation method of novel plastic woven bag
US11827774B2 (en) * 2017-12-18 2023-11-28 Borealis Ag Polymer blend composition for wire and cable applications with advantageous electrical properties

Also Published As

Publication number Publication date
GB8432810D0 (en) 1985-02-06

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