GB2061281A - Foamed polyolefin and a foamable polyolefin composition therefor - Google Patents
Foamed polyolefin and a foamable polyolefin composition therefor Download PDFInfo
- Publication number
- GB2061281A GB2061281A GB8032604A GB8032604A GB2061281A GB 2061281 A GB2061281 A GB 2061281A GB 8032604 A GB8032604 A GB 8032604A GB 8032604 A GB8032604 A GB 8032604A GB 2061281 A GB2061281 A GB 2061281A
- Authority
- GB
- United Kingdom
- Prior art keywords
- polyolefin
- composition
- foaming agent
- acidifier
- foamed
- 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.)
- Granted
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
- C08J9/04—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof using blowing gases generated by a previously added blowing agent
- C08J9/06—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof using blowing gases generated by a previously added blowing agent by a chemical blowing agent
- C08J9/08—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof using blowing gases generated by a previously added blowing agent by a chemical blowing agent developing carbon dioxide
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2323/00—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers
- C08J2323/02—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers not modified by chemical after treatment
Landscapes
- Chemical & Material Sciences (AREA)
- General Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Manufacture Of Porous Articles, And Recovery And Treatment Of Waste Products (AREA)
Abstract
A foamed (preferably crystalline aliphatic) polyolefin is made from a foamable polyolefin composition containing sodium carbonate as a foaming agent together with an acidifier such as citric acid. Use of the process in making polypropylene strapping tape enables a sodium carbonate/acidifier foaming agent system to be used to obtain a cell structure regular enough to inhibit fibrillation. This is achieved by using a foamable composition comprising 0.05 to 0.4% by weight of carbonate, extruding the foaming composition into an extrudate no thicker than 6 mm and stretching the extrudate after chilling to a stretch ratio of at least 4:1. The polypropylene may be homopolymer or copolymer with ethylene and/or butene-1 and the preferred acidifier is anhydrous citric acid.
Description
SPECIFICATION
A process for making a foamed polyolefin and a foamable polyolefin composition
This invention relates to a process for making foamed polyolefins and a foamable polyolefin composition. The process is especially suitable for making longitudinally oriented tape (for example, strapping tape) from compositions comprising a cheap foaming agent system and a crystalline polymer of propylene which is a homopolymer of propylene or a copolymer of propylene with up to 20% (by weight based on the weight of the copolymer) of ethylene and/or butene-1.
Copolymers comprising up to 8% of ethylene are preferred. Orientated polypropylene strapping tapes are foamed to reduce their tendency to suffer unintended fibrillation.
Commercially, polyolefins are foamed using expensive foaming agent systems despite the commercial use of cheap sodium bicarbonate/acidifier systems in making sponge rubber and earlier disclosures of the possible use of sodium bicarbonate as a foaming agent for polyethylene by old British patent specifications 524 063 and 753 259. The problem with sodium bicarbonate when used in crystalline polyolefins is that it produces an irregular cell structure. This is possibly because one of its decomposition products is water which has a high specific heat and appears to produce variations in the temperature of the molten polyolefin. These variations are difficult to counteract. Attempts to solve the problem led to more sophisticated foaming agent systems.For example, British
patent specification 1 006 926 discloses foaming polypropylene using a foaming agent system comprising sodium bicarbonate, an acidifier which is citric acid and a solid capable of being heated by an electromagnetic field. A more controlled foaming is achieved, but only at the cost of using electromagnetic heating and introducing into the composition extraneous material which need not otherwise be there.
It has now been discovered that anhydrous sodium carbonate can be used as a cheap foaming agent in polyolefins and that foaming is more easily controlled. Accordingly, this invention provides a process for making a foamed (preferably aliphatic and/or crystalline) polyolefin by heating a polyolefin composition containing an acidifier and from 0.05 to 4.0 (preferably 0.1 to 0.4, especially 0.1 to 0.18)% by weight of the polyolefin of a chemical foaming agent to a temperature above 900C at which the polyolefin is molten characterised in that the chemical foaming agent is anhydrous sodium carbonate and is optionally heated under conditions of shear (for example, as it passes through a screw extruder).
Conditions of shear appear to promote a more uniform decomposition of the sodium carbonate.
The invention also provides a foamable polyolefin composition for use in the process which contains an acidifier and 0.05 to 4.0 (or in the case of a masterbatch 2 to 35, preferably 7 to 18)% by weight of the polyolefin of anhydrous sodium carbonate.
More particularly the invention provides a process for making a foamed longitudinally orientated polypropylene tape (preferably 0.1 to 15 cm wide) wherein:
a) a foamable composition comprising a propylene polymer and a foaming agent system is heated in an extruder to a temperature (preferably 200 to 2600C) sufficient to activate the foaming agent system,
b) the heated composition is extruded into a foamed extrudate having a thickness of not more than 6 mm (preferably 3 to 5 mm),
c) the foamed extrudate is chilled to a temperature below the crystalline melting point of the propylene polymer (preferably below 1 300C), and
d) the chilled extrudate is stretched (after reheating if necessary) in the direction of extrusion to a stretch ratio of at least 4:1 and preferably from 7:1 to 11 ::1, and the process is characterised in that there is used as the foamable composition, a composition comprising acidifier and from 0.05 to 0.4 (preferably 0.1 to 0.1 8)% by weight of the propylene polymer of anhydrous sodium carbonate. The process enables anhydrous sodium carbonate to be used to produce a foam structure which is regular enough to inhibit unintended fibrillation of longitudinally orientated tape without the need to resort to post-extrusion electromagnetic heating.
Acidifiers used with chemical foaming agents are weak anhydrous acids or acid salts, for example, boric acid, tartaric acid, potassium hydrogen tartrate, oxalic acid, fumaric acid, oleic acid, chloroacetic acid, phthalic acid or sodium, potassium or calcium hydrogen salts of oxyacids of phosphorus but the preferred acidifier is anhydrous citric acid. Preferably, the foamable composition contains sufficient acidifier to ensure that the concentration of acidic hydrogen provided by the acidifier is about equal to or possibly slightly less than the concentration of sodium ions provided by the carbonate.
Particulate foaming agent and optionally particulate acidifer may be mixed with particulate polyolefin polymer using a tumble mixer or a rotary blade fluidising mixer or an internal mixer such as a Banbury mixer. Preferably, the foaming agent is mixed with a carrier to make a particulate masterbatch which is then mixed with particulate polyolefin polymer as described above. The carrier may be the polyolefin polymer itself, for example, polystyrene, polypropylene, polyethylene or a copolymer of ethylene with up to 33 (especially 3 to 20)% by weight of the copolymer of vinyl acetate and sometimes such copolymers may promote a better cell structure.Particles of sodium carbonate and/or acidifier may be used in combination with (and preferably coated with) long chain (e.g. 1 0 to 24 carbon atoms) fatty acids (e.g. stearic acid) or the esters (e.g. glycerol esters) in order to retard premature decomposition.
The preferred propylene polymer for making strapping tapes may contain up to 10% (by weight of the composition) of low, intermediate or high density polyethylene and/or up to 10% (by weight of the composition) of a mineral additive, for example, chalk or talc which act as additional fibrillation inhibitors. the propylene polymer composition may also contain (for example, up to 20% by weight of the composition) a rubber which is preferably an optionally diene modified ethylene/propylene rubber Preferably, the propylene polymer may contain the usual.
additives such as antioxidants, light stabilisers, extrusion aids such as stearates and pigments (especially carbon black) and preferably should have a melt flow index of from 0.1 to 25 g/10 minutes. Melt flow indices of 0.5 to 2 are preferred for strapping tape and of 3 to 8 for decorative tape. Melt flow index is measured according to British Standard 2782: Part 1,
Method 1 05C of 1970 using a 2.16 kg load except that when the melt flow index of a predominantly propylene polymer is being measured, the method is performed using a temperature of 2300C instead of 1900 C.
The invention is illustrated by the following example.
EXAMPLE
A foamable polypropylene composition was made by tumble blending together 97 parts by weight of propylene granules of melt flow index
1.5 g/1 0 minutes with 3 parts by weight of granules of a masterbatch of polyethylene and a sodium carbonate/acidifier foaming agent system and heating the mixture to 2300C in a screwextruder to activate the foaming agent system.
The masterbatch consisted of:
a) 84% of a copolymer of ethylene and 18% (by weight of the copolymer) of vinyl acetate and having a melt flow index 40 g/10 minutes,
b) 9% of sodium carbonate, and
c) 7% of citric acid all percentages being based on the weight of the masterbatch.
The heated mixture was extruded into foamed sheet 4 mm thick and 35 mm wide and chilled by passing the sheet through a water bath maintained at 300C. The chilled sheet was reheated to about 160"C and stretched to a stretch ratio of 8:1 in the direction of extrusion to produce tape 0.5 mm thick and 12 mm wide. The tape was found to have a cell structure which was sufficiently regular to inhibit unintentional fibrillation. The tape was suitable for embossing which further reduces its tendency to fibrillate.
The process of this invention may also be used to make fibrillation resistant filaments and fibres.
Preferably, the polyolefins used to make fibres have melt flow indices of from 7 to 20 g/1 0 minutes.
Claims (4)
1. A process for making a foamed polyolefin by heating a polyolefin composition containing an acidifier and from 0.05 to 4.0% by weight of the polyolefin of a chemical foaming agent to a temperature above 900C at which the polyolefin is molten characterised in that the chemical foaming agent is anhydrous sodium carbonate.
2. A process according to claim 1 wherein the composition is heated under conditions of shear.
3. A process according to claim 1 or claim 2 for making a foamed longitudinally orientated polypropylene tape wherein:
a) a foamable composition comprising a propylene polymer and a foaming agent system is heated in an extruder to a temperature sufficient to activate the foaming agent system,
b) the heated composition is extruded into a foamed extrudate having a thickness of not more than 6 mm,
c) the foamed extrudate is chilled to a temperature below the crystalline melting point of the propylene polymer, and
d) the chilled extrudate is stretched in the direction of extrusion to a stretch ratio of at least 4:1, and the process is characterised in that there is used as the foamable composition, a composition comprising acidifier and from 0.05 to 0.4% by weight of the propylene polymer of anhydrous sodium carbonate.
4. A foamable polyolefin composition for use in a process according to any one of the preceding claims which contains an acidifier and 0.05 to 2.0 (or in the case of a masterbatch 2 to 35)% by weight of the polyolefin of anhydrous sodium carbonate.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8032604A GB2061281B (en) | 1979-10-23 | 1980-10-09 | Foamed polyolefin and a foamable polyolefin composition therefor |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB7936781 | 1979-10-23 | ||
| GB8032604A GB2061281B (en) | 1979-10-23 | 1980-10-09 | Foamed polyolefin and a foamable polyolefin composition therefor |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2061281A true GB2061281A (en) | 1981-05-13 |
| GB2061281B GB2061281B (en) | 1983-10-19 |
Family
ID=26273331
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8032604A Expired GB2061281B (en) | 1979-10-23 | 1980-10-09 | Foamed polyolefin and a foamable polyolefin composition therefor |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2061281B (en) |
Cited By (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0482007A1 (en) * | 1989-05-16 | 1992-04-29 | Huber Corp J M | Endothermic blowing agents compositions and applications. |
| US5218006A (en) * | 1992-06-01 | 1993-06-08 | Reedy Michael E | Process for producing polystyrene foam |
| US5234963A (en) * | 1992-05-13 | 1993-08-10 | Gaia Research | Production of encapsulated chemical foaming concentrates |
| US5250224A (en) * | 1989-05-16 | 1993-10-05 | J. M. Huber Corporation | Foamed products containing endothermic blowing agents and processes |
| US5252618A (en) * | 1989-05-16 | 1993-10-12 | J. M. Huber Corporation | Endothermic blowing agents for strengthening weld lines in molded thermoplastic resins and products |
| US5302455A (en) * | 1989-05-16 | 1994-04-12 | J. M. Huber Corporation | Endothermic blowing agents compositions and applications |
| US5306736A (en) * | 1989-05-16 | 1994-04-26 | J. M. Huber Corporation | Endothermic blowing agents for surface migration of components in foamed products, compositions and applications |
| US5317044A (en) * | 1989-05-16 | 1994-05-31 | J. M. Huber Corporation | Endothermic blowing agents for surface migration of components in foamed products, compositions and applications |
| US5627218A (en) * | 1995-03-20 | 1997-05-06 | Bradt; Rexford H. | Compartmented thermoplastic pellets |
| EP0960826A2 (en) * | 1998-03-03 | 1999-12-01 | Fort James Corporation | Method for the production of extruded sheets and microwaveable containers obtained from said sheets |
| US6468451B1 (en) | 2000-06-23 | 2002-10-22 | 3M Innovative Properties Company | Method of making a fibrillated article |
| US6692823B2 (en) | 2001-12-19 | 2004-02-17 | 3M Innovative Properties Company | Microfibrillated articles comprising hydrophillic component |
| WO2011018398A1 (en) * | 2009-08-14 | 2011-02-17 | Chemische Fabrik Budenheim Kg | Foaming agent for plastics |
| ITMI20102368A1 (en) * | 2010-12-22 | 2012-06-23 | Indesit Co Spa | METHOD OF PREPARATION OF A THERMOPLASTIC ITEM AND ITEM PREPARED WITH THIS METHOD |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6680114B2 (en) | 2001-05-15 | 2004-01-20 | 3M Innovative Properties Company | Fibrous films and articles from microlayer substrates |
| US20030211310A1 (en) | 2001-06-21 | 2003-11-13 | Haas Christopher K. | Foam and method of making |
| US6753080B1 (en) | 2002-01-29 | 2004-06-22 | 3M Innovative Properties Company | Receptor medium having a microfibrillated surface |
-
1980
- 1980-10-09 GB GB8032604A patent/GB2061281B/en not_active Expired
Cited By (24)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0482007A1 (en) * | 1989-05-16 | 1992-04-29 | Huber Corp J M | Endothermic blowing agents compositions and applications. |
| EP0482007A4 (en) * | 1989-05-16 | 1992-05-13 | J.M. Huber Corporation | Endothermic blowing agents compositions and applications |
| US5250224A (en) * | 1989-05-16 | 1993-10-05 | J. M. Huber Corporation | Foamed products containing endothermic blowing agents and processes |
| US5252618A (en) * | 1989-05-16 | 1993-10-12 | J. M. Huber Corporation | Endothermic blowing agents for strengthening weld lines in molded thermoplastic resins and products |
| US5302455A (en) * | 1989-05-16 | 1994-04-12 | J. M. Huber Corporation | Endothermic blowing agents compositions and applications |
| US5306736A (en) * | 1989-05-16 | 1994-04-26 | J. M. Huber Corporation | Endothermic blowing agents for surface migration of components in foamed products, compositions and applications |
| US5317044A (en) * | 1989-05-16 | 1994-05-31 | J. M. Huber Corporation | Endothermic blowing agents for surface migration of components in foamed products, compositions and applications |
| US5234963A (en) * | 1992-05-13 | 1993-08-10 | Gaia Research | Production of encapsulated chemical foaming concentrates |
| US5218006A (en) * | 1992-06-01 | 1993-06-08 | Reedy Michael E | Process for producing polystyrene foam |
| US5342857A (en) * | 1992-06-01 | 1994-08-30 | Reedy International Corporation | Process for producing polystyrene foam |
| US5627218A (en) * | 1995-03-20 | 1997-05-06 | Bradt; Rexford H. | Compartmented thermoplastic pellets |
| EP0960826A3 (en) * | 1998-03-03 | 2000-01-19 | Fort James Corporation | Method for the production of extruded sheets and microwaveable containers obtained from said sheets |
| EP0960826A2 (en) * | 1998-03-03 | 1999-12-01 | Fort James Corporation | Method for the production of extruded sheets and microwaveable containers obtained from said sheets |
| US6468451B1 (en) | 2000-06-23 | 2002-10-22 | 3M Innovative Properties Company | Method of making a fibrillated article |
| US6646019B2 (en) | 2000-06-23 | 2003-11-11 | 3M Innovative Properties Company | Fibrillated foam article |
| US6692823B2 (en) | 2001-12-19 | 2004-02-17 | 3M Innovative Properties Company | Microfibrillated articles comprising hydrophillic component |
| WO2011018398A1 (en) * | 2009-08-14 | 2011-02-17 | Chemische Fabrik Budenheim Kg | Foaming agent for plastics |
| CN102471514A (en) * | 2009-08-14 | 2012-05-23 | 化学制造布敦海姆两合公司 | Foaming agent for plastics |
| JP2013501837A (en) * | 2009-08-14 | 2013-01-17 | ケミッシュ ファブリーク ブーデンハイム カーゲー | Plastic foaming agent |
| CN102471514B (en) * | 2009-08-14 | 2013-08-14 | 化学制造布敦海姆两合公司 | Foaming agent for plastics |
| RU2542279C2 (en) * | 2009-08-14 | 2015-02-20 | Хемише Фабрик Буденхайм Кг | Foaming agents for plastics |
| ITMI20102368A1 (en) * | 2010-12-22 | 2012-06-23 | Indesit Co Spa | METHOD OF PREPARATION OF A THERMOPLASTIC ITEM AND ITEM PREPARED WITH THIS METHOD |
| WO2012085878A1 (en) * | 2010-12-22 | 2012-06-28 | Indesit Company S.P.A. | Method for preparing a thermoplastic item and an item prepared with said method |
| RU2587166C2 (en) * | 2010-12-22 | 2016-06-20 | Индезит Компани С.П.А. | Method of producing articles from thermoplastic material and product obtained using said method |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2061281B (en) | 1983-10-19 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| GB2061281A (en) | Foamed polyolefin and a foamable polyolefin composition therefor | |
| EP0188540B1 (en) | Foams of linear low density polyethylene and a method for their preparation | |
| US20070149630A1 (en) | Composition for polyolefin resin foam and foam thereof, and method for producing foam | |
| JPS6011975B2 (en) | Method for manufacturing polyolefin resin foam sheet | |
| JPH10139943A (en) | Composition based on polyolefin and ethylene/vinyl acetate copolymer | |
| EP0143545B1 (en) | Masterbatch composition containing a resin and a foaming agent | |
| EP0036562A2 (en) | Foamable olefin polymer compositions stabilized with certain higher ethers, esters or anhydrides, foaming process using them and foam article produced | |
| US3645930A (en) | Expandable compositions and products | |
| US4940735A (en) | Blowing agent masterbatch for the preparation of polystyrene foams | |
| EP0213788A2 (en) | Method for improving the clarity of propylene polymers | |
| US3461087A (en) | Method of making a foamable polymer and foamable composition obtained therefrom | |
| EP0585147B1 (en) | Low density polyolefin foam, foamable polyolefin compositions and process for making same | |
| US5208266A (en) | Lightly crosslinked polymeric foams and process for making same | |
| EP0536147B1 (en) | Antistatic polyolefin foams and films and method of making the foam and antistatic composition | |
| JP3370469B2 (en) | Foamed sheet of polypropylene resin composition | |
| CN105542305A (en) | Halogen-free high-temperature-resisting flame-resistant material high in oxygen index and preparation method and application thereof | |
| RU2320684C2 (en) | Polyolefin-base foam plastic | |
| JPH0748557A (en) | Foaming agent composition and production of polyolefin resin foam by using the same | |
| JPH11269288A (en) | Porous film and production thereof | |
| JPS6367494B2 (en) | ||
| JPH0231087B2 (en) | HATSUHOSHASHUTSUSEIKEIYOHORIPUROPIRENSEIKEIZAIRYO | |
| JPH0257491B2 (en) | ||
| JPS6339932A (en) | Expandable resin composition | |
| JPH0726077A (en) | Thermoplastic olefin elastomer or resin material for calendering | |
| GB2097403A (en) | Closed-cell ethylene polymer stretched films |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |