WO2021240130A1 - Procédé de production d'un polymère hydrosoluble, polymère hydrosoluble ainsi produit et composition polymère hydrosoluble traitable - Google Patents

Procédé de production d'un polymère hydrosoluble, polymère hydrosoluble ainsi produit et composition polymère hydrosoluble traitable Download PDF

Info

Publication number
WO2021240130A1
WO2021240130A1 PCT/GB2021/051124 GB2021051124W WO2021240130A1 WO 2021240130 A1 WO2021240130 A1 WO 2021240130A1 GB 2021051124 W GB2021051124 W GB 2021051124W WO 2021240130 A1 WO2021240130 A1 WO 2021240130A1
Authority
WO
WIPO (PCT)
Prior art keywords
water
composition
polymer
weight
soluble polymer
Prior art date
Application number
PCT/GB2021/051124
Other languages
English (en)
Inventor
Peter Morris
Original Assignee
Peter Morris Research And Development Limited
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
Priority claimed from GB2007826.7A external-priority patent/GB2595641A/en
Priority claimed from US16/882,794 external-priority patent/US11718010B2/en
Application filed by Peter Morris Research And Development Limited filed Critical Peter Morris Research And Development Limited
Priority to EP21728272.2A priority Critical patent/EP4153392A1/fr
Priority to AU2021279371A priority patent/AU2021279371A1/en
Priority to KR1020227044119A priority patent/KR20230016192A/ko
Priority to BR112022024229A priority patent/BR112022024229A2/pt
Priority to JP2022573506A priority patent/JP2023528600A/ja
Priority to CN202180049541.1A priority patent/CN115812026A/zh
Priority to CA3184903A priority patent/CA3184903A1/fr
Publication of WO2021240130A1 publication Critical patent/WO2021240130A1/fr

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
    • B29B9/00—Making granules
    • B29B9/02—Making granules by dividing preformed material
    • B29B9/06—Making granules by dividing preformed material in the form of filamentary material, e.g. combined with extrusion
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
    • B29B13/00—Conditioning or physical treatment of the material to be shaped
    • B29B13/04—Conditioning or physical treatment of the material to be shaped by cooling
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
    • B29B7/00—Mixing; Kneading
    • B29B7/002—Methods
    • B29B7/007—Methods for continuous mixing
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
    • B29B7/00—Mixing; Kneading
    • B29B7/80—Component parts, details or accessories; Auxiliary operations
    • B29B7/82—Heating or cooling
    • B29B7/826—Apparatus therefor
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
    • B29B9/00—Making granules
    • B29B9/12—Making granules characterised by structure or composition
    • 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
    • C08J3/00—Processes of treating or compounding macromolecular substances
    • C08J3/12—Powdering or granulating
    • 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
    • C08J2300/00—Characterised by the use of unspecified polymers
    • C08J2300/14—Water soluble or water swellable polymers, e.g. aqueous gels
    • 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
    • C08J2329/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an alcohol, ether, aldehydo, ketonic, acetal, or ketal radical; Hydrolysed polymers of esters of unsaturated alcohols with saturated carboxylic acids; Derivatives of such polymer
    • C08J2329/02—Homopolymers or copolymers of unsaturated alcohols
    • C08J2329/04—Polyvinyl alcohol; Partially hydrolysed homopolymers or copolymers of esters of unsaturated alcohols with saturated carboxylic acids
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/16—Halogen-containing compounds
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K5/00—Use of organic ingredients
    • C08K5/0008—Organic ingredients according to more than one of the "one dot" groups of C08K5/01 - C08K5/59
    • C08K5/0016—Plasticisers
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K5/00—Use of organic ingredients
    • C08K5/04—Oxygen-containing compounds
    • C08K5/05—Alcohols; Metal alcoholates
    • C08K5/053—Polyhydroxylic alcohols

Definitions

  • the present invention relates to a polymer composition, particularly but not exclusively to polyvinyl alcohol polymers, and to methods for their production.
  • Poly vinyl alcohol is recognized as one of the very few vinyl polymers soluble in water that is also susceptible of ultimate biodegradation in the presence of suitably acclimated microorganisms. Accordingly, increasing attention is being devoted to the preparation of environmentally compatible PVA-based materials for a wide range of applications.
  • PVA has excellent film and thin-walled container forming properties, demonstrating a high degree of impermeability to a number of gases, making it highly suitable for use in packaging products for release in an aqueous environment. It also has high adhesive strength, and is nontoxic. However, these properties are dependent on humidity due to the polymer absorbing water which reduces its tensile strength but increases its elongation and tear strength.
  • the Melt Flow Index This relates to the ease of flow of the melt of the polymer, defined as the mass of the polymer, in grams, flowing in ten minutes through a capillary of a specific diameter and length by a pressure applied via prescribed alternative gravimetric weights for alternative prescribed temperatures.
  • One such method is described in the standard ISO 1133.
  • a higher MFI is required to provide a thin walled moulding.
  • EP1112316 B1 (PVAXX Technologies Limited) includes a fatty acid amide in an amount up to 5% by weight.
  • the fatty acid provides lubrication between the polymer chains thereby increasing the melt flow of the polymer.
  • they are insoluble, melting and coating the polymer during processing, which may impede dissolution of the polymer.
  • the amount of lubricant that can be used is limited due to excess lubricant (generally above 5% by weight of the PVA) separating out of the blend, thereby restricting their ability to improve the MFI of a polymer.
  • the polymer is produced by polymerisation from vinyl acetate and subsequent hydrolysis of the polyvinyl acetate (PVAc) which is formed.
  • PVA and PVA-derived polymers are soluble in water with their solubility being determined by the molecular weight of the polymer and the degree of hydrolysis, i.e. the percentage of acetate groups of the starting polymer (PVAc) that has been replaced with OH groups. The higher the degree, the lower the solubility and the speed of solution. The differences are much more marked at low dissolving temperatures than at high ones due to the formation of crystalline zones within the polymer.
  • PVA requires the removal of volatiles from the composition before melt processing as without such removal processing is difficult due to the formation of steam and subsequent foaming of the polymer. Drying is generally achieved using standard drying equipment at a temperature of 90°C for a period of 4-9 hours, depending on make, model and formulation.
  • Further aims of the present invention are to provide methods for the production and extrusion and/or moulding of water-soluble polymer compositions.
  • a method of creating a water soluble polymer comprising the steps of: extruding a water soluble polymer composition from an extruder barrel without the use of a die, wherein the extruder barrel is not vented other than via its extruder outlet, to produce an irregularly shaped polymer extrudate; directing the irregularly shaped polymer extrudate onto a chilled conveyor to rapidly cool the irregularly shaped polymer extrudate to below 60°C; granulating the irregularly shaped polymer extrudate to form a granulate.
  • the granulation of the irregularly shaped polymer extrudate may occur immediately following the chilled conveyor without a further drying step.
  • the method may further comprise the step of forming the granulate into a water-soluble polymer product.
  • the water soluble polymer may comprise a water soluble polymer composition with at least 15% by weight of the total weight of the composition of a hygroscopic salt to act as a lubricant to render the polymer extrudable and/or mouldable and with a solvent polymer plasticizer, wherein the solvent polymer plasticizer is mono-propylene glycol or di-propylene glycol, and wherein the water content of the composition is of less than 10% by weight of the total weight of the composition.
  • a solvent polymer plasticizer is mono-propylene glycol or di-propylene glycol
  • the hygroscopic salt may be provided in a higher amount by weight than the solvent polymer plasticizer.
  • the hygroscopic salt may be an anhydrous or hydrated salt selected from the group consisting of: sodium chloride, sodium citrate, magnesium chloride, calcium chloride, potassium chloride, sodium sulphate, sodium carbonate, potassium carbonate, and ammonium carbonate.
  • the hygroscopic salt may be a water-soluble salt which will dissolve at a rate of at least 10% by weight in 90°C water in ten minutes.
  • the hygroscopic salt may have a water content of less than 10% by weight of the total weight of the composition.
  • the hygroscopic salt may be included in an amount of at least 25% by weight of the total weight of the composition.
  • the hygroscopic salt may be included in an amount of at least 30% by weight of the total weight of the composition.
  • the hygroscopic salt may be in the anhydrous form.
  • the water-soluble polymer and hygroscopic salt may be provided in solid form.
  • the polymer may comprise a polyvinyl alcohol polymer.
  • the method may further comprise the step of extruding the water-soluble polymer composition without using a die.
  • the method may further comprise the step of extruding the water-soluble polymer composition onto a chilled conveyor.
  • the chilled conveyor may be at or below a temperature of between 10°C and 30°C.
  • the method may further comprise the step of granulating the water-soluble polymer composition immediately following the chilled conveyor without a further drying step.
  • the water-soluble polymer may comprise a wax to improve humidity resistance.
  • the present invention provides a melt-processable water soluble polymer composition comprising a blend of a water soluble polymer with at least 15% by weight of the total weight of the composition of a hygroscopic salt to act as a lubricant to render the polymer extrudable and/or mouldable, wherein the composition has a water content of less than 10% by weight.
  • the water-soluble polymer may be solid at ambient temperature. More preferably, the polymer comprises a polyvinyl alcohol polymer.
  • the PVA used in the present invention is not limited to any particular degree of hydrolysis. Partially or fully hydrolysed PVA may be used in the present invention. Similarly, the PVA is not limited to a particular molecular weight. The PVA may have a relatively low molecular weight of around 20,000 up to and beyond a molecular weight of 150,000.
  • the PVA preferably has a maximum water content of 5% by weight. It has been surprisingly found that the hygroscopic salt not only draws water from the PVA but also acts as an internal lubricant for the PVA increasing its Melt Flow Index.
  • the hygroscopic salt is an anhydrous or hydrated salt selected from an alkaline or alkaline earth metal salt.
  • a salt that is approved for food and/or pharmaceutical use and/or has other properties that may impart additional benefits in the end product, such as a water softener.
  • the salt is selected from the group consisting of sodium chloride, sodium citrate, magnesium chloride, calcium chloride, potassium chloride, sodium sulphate, sodium carbonate, potassium carbonate, and ammonium carbonate especially being sodium chloride or citrate.
  • a preferred embodiment of the first aspect of the invention comprises a blend of a water- soluble polymer and an amount of sodium chloride effective to render the blend extrudable.
  • the salt has a water content of less than 10% by weight, preferably less than 1% by weight, more preferably less than 0.5% by weight, especially less than 0.2%. Ideally, the salt is in the anhydrous form.
  • the salt may be micronized, for example the particles having a mean size of less than 100 microns, preferably being in the range 0.03-75 pm, especially 60-70 pm.
  • the salt may also be coated to improve its properties, for example with sodium aluminosilicate, silicon dioxide and/or sodium hexacyanoferrate.
  • One such example is sodium chloride salt coated with Sodium Aluminosilicate 0.5% (E554), Silicon Dioxide 0.75% (E551) and Sodium hexacyanoferrate (E535) as an anti-caking agent, available from Custom Powders (www.custompowders.co.uk).
  • the salt may be included in the composition in an amount up to 75% by weight of the total weight of the formulation.
  • the salt is included in an amount of at least 15%, and preferably at least 20%, by weight of the total weight of the formulation, more preferably at least 25% by weight, more preferably at least 30% by weight, more preferably at least 35% by weight, more preferably at least 40% by weight, more preferably 45% by weight, and especially at least 50% by weight.
  • the composition may be compounded with optional additives to improve processability of the composition, such as plasticizers to enhance flexibility and/or lower the melt temperature of the polymer under extrusion or moulding, stabilizers to increase heat resistance and/or pigments to add colour.
  • additives such as plasticizers to enhance flexibility and/or lower the melt temperature of the polymer under extrusion or moulding
  • stabilizers to increase heat resistance and/or pigments to add colour.
  • thermal stabilizers such as metal stearates
  • the composition is preferably free from any fatty acid amides or esters.
  • the inbound water from other constituents within the composition surface such as the polymer itself, treat the salt to enable it to act as an internal lubricant.
  • An “internal” lubricant functions to improve lubrication between polymer chains.
  • the use of a salt as a lubricant removes the need to use other types of prior art internal lubricant, such as fatty acid amides or esters.
  • An example composition without solvent plasticizer may be as follows:
  • PVOH (80% hydrolyzed) 69.7%
  • the sodium chloride is more readily soluble in water than the polymer, but is not a thermoplastic resin. Therefore, it would be expected that the angular crystalline structure of the salt would not mix with the polymer and would actually impede melt flow. Surprisingly, this is not found to be the case.
  • the salt is provided in a higher percentage by weight than the solvent polymer plasticizer. More preferably, the ratio of salt to solvent polymer plasticizer is 1.25-12: 1, especially 1.25-7:1, ideally 4-5:1.
  • the composition may include a solvent polymer plasticizer, preferably being a hygroscopic organic solvent, more preferably being selected from glycerine (also known as glycerin or glycerol) and propylene glycol.
  • a solvent polymer plasticizer preferably being a hygroscopic organic solvent, more preferably being selected from glycerine (also known as glycerin or glycerol) and propylene glycol.
  • the solvent polymer plasticizer is mono-propylene glycol, and in an even more preferable embodiment, the solvent polymer plasticizer is di-propylene glycol.
  • a melt-processable water soluble polymer composition comprising a blend of a water soluble polymer with at least 15% by weight of a hygroscopic salt to act as a lubricant to render the polymer extrudable and/or mouldable.
  • a soluble polymer internal lubricant comprising a blend of a hygroscopic salt and solvent polymer plasticizer of the salt.
  • the lubricant according to the present invention may be blended with a water-soluble polymer for processing thereof.
  • a further aspect of the present invention provides a melt-processable water soluble polymer composition comprising a blend of a water soluble polymer with an internal lubricant to render the polymer extrudable and/or mouldable, the lubricant comprising a hygroscopic salt, preferably an anhydrous or hydrated metal salt, blended with a solvent polymer plasticizer.
  • the lubricant is in accordance with the preceding aspect of the invention.
  • the salt prefferably has minimal water content, preferably the salt having a water content of less than 10% by weight, the salt comprising at least 15% by weight of the total weight of the formulation, more preferably at least 40% by weight, especially at least 50% by weight.
  • the lubricant according to the invention when mixed with the water-soluble polymer preferably has a Melt Flow Index of at least 20g (10 mins/190°C/2.16kg, under ISO 1133), more preferably at least 40g, especially 60g.
  • compositions of the present invention may be used in foodstuffs and/or pharmaceuticals. Therefore, it is to be appreciated that, if possible, the lubricant and other constituents of the composition have been approved for food and/or pharmaceutical use.
  • composition according to the present invention may be provided in any suitable form for further processing but preferably is provided in the form of a powder, tablet or pellets for use in extrusion and/or moulding of an extruded and/or moulded product, such as an extruded filament, containing the soluble polymer.
  • the composition may be manufactured by any conventional method, such as by melt compounding or cold processing, which in this latter case may include calendaring, adapted calendaring, and/or compaction. Cold pressing, and more preferably adapted calendaring, may be the technique of choice.
  • compositions of the present invention may further include a plasticizer to lower the melt temperature of the polymer under extrusion and/or moulding.
  • the plasticizer may be selected from the group consisting of glycerine, ethylene glycol, triethylene glycol, low molecular weight polyethylene glycols and low molecular weight amides.
  • a preferred plasticizer is glycerine, and more preferably mom-propylene glycol or most preferably di-propylene glycol.
  • the plasticizer may also function as the solvent polymer plasticizer of the salt internal lubricant.
  • a further aspect of the invention provides a method of making a water-soluble polymer composition comprising blending a water soluble polymer with at least 15% by weight of the total weight of the composition of a hygroscopic salt to act as a lubricant to render the polymer extrudable and/or mouldable, wherein the water content of the composition is less than 10% by weight, the method optionally including adding a solvent polymer plasticizer.
  • a further aspect of the invention provides a method of extruding and/or moulding a water- soluble polymer composition comprising softening a composition according to the preceding aspects of the present invention to form a melt flow. Preferably, heat and/or pressure soften the composition to create a melt flow.
  • the melt flow preferably has a Melt Flow Index of at least 20g (10 mins/190°C/2.16kg, under ISO 1133), more preferably at least 40g, and especially 60g.
  • the polymer composition is moulded into a form having a thickness of less than 200 microns, preferably less than 100 microns thereby enabling the form to dissolve within 80 seconds at 5°C in aqueous solution.
  • the moulded form may be any thin walled moulding, such as a container, or a film. Extrusion is also possible, although the composition of the present invention is especially beneficial for mouldings.
  • a further aspect of the invention provides for a water-soluble polymer product formed in accordance with the preceding aspect of the invention.
  • a further aspect of the invention provides for a melt-processable water soluble polymer composition
  • a melt-processable water soluble polymer composition comprising: a blend of a water soluble polymer with a hygroscopic salt to act as a lubricant to render the polymer extrudable and/or mouldable, a solvent polymer plasticizer; and a wax, wherein the wax content of the composition is at least 0.3% by weight of the total weight of the composition; wherein the water content of the composition is of less than 10% by weight of the total weight of the composition; and the hygroscopic salt is included in the composition in an amount of at least 15% by weight of the total weight of the composition.
  • the melt-processable water soluble polymer composition may have a wax content of at least 1.0% by weight of the total weight of the composition.
  • the wax may be glycerol mono stearate.
  • melt-processable compositions of the present invention may be processed by any known thermoprocessing method, including but not limited to, injection moulding, compression moulding, rotational moulding and film extrusion.
  • the compositions are particularly suitable for thin-walled mouldings.
  • the melt-processable compositions of the invention are suitable for the manufacture of any article currently made from extrudable and/or mouldable polymers, including films, containers and bottles.
  • the compositions are suited to the manufacture of filaments and fibre, for use in spunbond, non-woven and melt-blowing applications.
  • the composition is suitable also for manufacture of such articles as detergent and agro chemical sachets and containers, mulch films, plant pots, domestic bags, diapers, drinking straws, fern care products, hangers, incontinence pads, sachets, six pack rings, disposable clothing, expanded foams, gloves, film canisters, golf tees, shot gun cartridges, bed pans, bottles, bowls, cotton buds, hospital curtains, " one-use " sterile products and packaging materials.
  • PVA generally has moisture content up to 5% by weight. This has to be reduced to below 1% to avoid processing issues on standard thermoplastic equipment, such as the generation of volatiles which causes foaming.
  • the polymer is dried in a standard polymer dryer for 4-8 hours at 90°C. It has been found that the addition of a hygroscopic salt in a particular amount, preferably having a low water content or being anhydrous, removes water from the surrounding PVA. More surprisingly, the absorption of water by the salt provides a self-lubricating coating on the salt which is then able to act as an internal lubricant for the PVA.
  • the desiccant effect of the salt reduces drying time to 2-4 hours enabling a substantial energy saving in the polymer production and furthermore, the lubrication brought about by the salt greatly increases the Melt Flow Index of composition such that the PVA may be readily extruded and/or moulded into products and, in particular to thin forms of less than 200 microns making it suitable for applications where dissolution of the film and/or moulding is required at temperatures as low as 5°C within a short time period (under 2 minutes).
  • the self-lubricating effect is still active at low moisture levels of less than 1%, i.e. even during the drying process. It is feasible that the temperature may be decreased further and therefore closer to 0°C, and the time may also be decreased.
  • the hygroscopic salt such as sodium chloride
  • polymer plasticizers such as hygroscopic salt solvents including glycerine or propylene glycol, and particularly mom- propylene glycol or most preferably di-propylene glycol.
  • Absorption of water by the salt appears to act as a surface treatment enabling non solvent plasticizers to be used in the formulation, if desired.
  • Anhydrous salts would not normally be considered as suitable for internal lubrication of water-soluble polymers.
  • precipitated calcium carbonate (PCC) has been used in small amounts (2-3%).
  • Alcohol plasticizers are not solvents of PCC so high loadings have to be used to produce high melt flow resulting in very ductile products as the PVA becomes encapsulated around the PCC particles. Melt flow indexes are also disappointing.
  • the present invention uses glycerine, mono-propylene glycol, or di-propylene glycol, which are solvents of anhydrous sodium chloride, to partially dissolve the outer surface of the sodium chloride to provide a lubricant within the polymer chains. This produces a comparatively high MFI and increases the solubility of the polymer, whilst decreasing its ductility (a desirable trait).
  • Sodium chloride is one possible hygroscopic salt which can be used here.
  • Sodium citrate and magnesium chloride are other possible alternatives, as are calcium chloride, potassium chloride, sodium sulphate, sodium carbonate, potassium carbonate, and ammonium carbonate.
  • the requisite characteristics of the hygroscopic salt for the present invention are that the hygroscopic salt is water-soluble, having the ability to absorb atmospheric water, and/or which will achieve a dissolution rate of at least 10% by weight in 90°C water in 10 minutes.
  • PVA polymer
  • sodium chloride lubricant
  • glycerin plasticizer
  • thermal plasticizers were mixed in a bell tub, low-shear mixer for 3 minutes.
  • the mix was then fed into a compounder via a screw and formed into pellets via an adapted calendaring process.
  • the adapted calendaring process causes partial or complete melting of the PVA as a result of frictional shear as it is passed between the roller and die, causing agglomeration before extrusion through the die.
  • the temperature of the pre-extrudate varied from 110°C to 140°C and the formed pellets were then placed in a tray polymer dryer for 3 hours at 90°C.
  • the samples were moulded using a 50 tonne moulding press in automatic mode with a cycle time of 7-10 seconds using a mould with a hot runner system at 180°C to 200°C.
  • the screw temperature profile (in °C) from the hopper to tip was 160, 170, 180, 180-190.
  • the part wall section was measured between 600 - 350 microns.
  • Formulations were made according to the method above having the ingredients shown in Table 1 below mixed in the given percentage by weight. 88% hydrolysed PVA was used in each formulation and the thermal stabiliser was calcium stearate. The Melt Flow Index (MFI) was determined according to the analysis given above.
  • Formulation 2 shown in Table 1 above was found to have a white/cream colour with the following properties:
  • Formulations were made according to the method above having the ingredients shown in Table 2 below mixed in the given percentages by weight. 88% hydrolysed PVA was used in each formulation. The Melt Flow Index (MFI) was determined according to the analysis given above. The part wall section of the moulded formulations was measured from 600 microns to 100 microns. Table 2
  • Formulations were made according to the method above having the ingredients mixed in the percent by weights shown in Table 3 below. 98% hydrolysed PVA was used in formulation 10-13 and 80% hydrolysed PVA was used in formulations 14-16.
  • the formulations were moulded using a Boy 50 tonne moulding process in automatic mode with a cycle time of 20 seconds using a mould with a cold runner system.
  • the screw temperature profile (in °C) from the hopper to tip was 160, 170, 180, 180, 220.
  • the part wall section was measured from 600 to 2000 microns.
  • Formulation 17 was prepared as a blend in a similar way to Formulation 2 of Example 1 but having sodium citrate in place of sodium chloride, as follows:
  • Processing temperature was 190-200°C with a residence time of up to 30 minutes. Drying time was 4 hours at 90°C. The MFI is again substantially higher with the salt included in the composition.
  • Formulations 2 and 17 were capable of being moulded into a range of containers of various sizes and colours and were suitable for injection moulding.
  • the use of sodium citrate as the polymer lubricant provides additional advantages if it is used for packaging laundry products as it acts as a water softener.
  • Example 5
  • Table 4 clearly shows the importance of the amount of salt and water contained within the formulation on drying time and on MFI.
  • the formulation has a higher percentage of salt (of at least 15%, preferably at least 20%, and more preferably at least 40%) with minimal or no water content.
  • Formulations C and D which contained 13 and 17% water respectively were very sticky formulations that were not free-flowing making them unsuitable for compounding. Additionally, the excess drying times resulted in undesirable glycerine vapour loss.
  • the ratio (typically expressed as a percentage) of partial pressure for water vapor in a given environment compared to the equilibrium vapor pressure of pure water is known as relative humidity (RH).
  • RH relative humidity
  • the RHo is temperature-dependent and is typically expressed as a RHo value at a given temperature.
  • the RHo of crystalline NaCl at 20 degrees Celsius (deg. C) is approximately 77% RH - that is, when ambient temperature is at 20 deg. C, water vapor from the atmosphere will spontaneously be adsorbed onto and solvate NaCl crystals when ambient RH is at or above 77%.
  • a material with a low RHo value tends to absorb moisture more readily and may serve well as desiccants.
  • a material with a high RHo tends to absorb moisture less readily.
  • having a higher RHo advantageously reduces requirements for secondary packaging, and provides a more structurally stable product when opened to an unprotected environment.
  • formulations comprising PVA, sodium chloride and glycerine as outlined above is that, although the lubricating effect of the glycerine and salt combination aids melt processing, the resultant mouldings are susceptible to moisture uptake, and secondary packaging is required with high moisture- and gas-barrier properties.
  • Table 5 As shown in Table 5, it was found that using propylene glycol as the solvent polymer plasticizer surprisingly resulted in a less water-absorbent and thus more stable PVA-based polymer product relative to comparable formulations using glycerine as the solvent polymer plasticizer. Whereas formulations 7-9 with glycerine demonstrated an RHo at 20°C of 62% to 66%, all formulations with propylene glycol had a substantially higher
  • formulations with di-propylene glycol were found to be even more stable than comparable formulations with mono-propylene glycol; formulations 1-3 with di propylene glycol had an RHo at 20°C of 80% to 83%, whereas formulations 4-6 with mono-propylene glycol had a lower RHo at 20°C of 76% to 77%.
  • the deliquescent point of sodium chloride is around 77% RHo at 20°C; however, the resultant moldings made with formulations to include PVA, sodium chloride and glycerine have a tendency to deliquesce over 60 RHo at 20°C.
  • the surprising effect of substitution of di-propylene glycol for glycerine is that the deliquescent point of the sodium chloride is raised over 82 RHo at 20°C. This reduces the specification requirement for secondary packaging, as well as producing a more dimensionally stable product when opened to an unprotected environment.
  • extrusion is achieved via a slot die or strand die to manufacture PVA resin.
  • Both the slot die and strand die provide sufficient back-pressure to create an even flow of polymer melt from the extruder to where the extrudate must be cooled. This is typically performed by water immersion or by cooling with ambient or chilled air.
  • PVA blended with lubricating hygroscopic salts, as formed according to the present method is more soluble and more brittle, and therefore unsuited for strand extrusion and water cooling.
  • the pellets When cooled in water, the pellets become slimy due to dissolution, sticking together and therefore further drying is required. Strands will also become brittle due to the reduced polymer and high salt content, as well as loss of plasticizer by up to 0.75% during air cooling.
  • the process is not stable due to strand breakage and loss of material, resulting in process down-time.
  • the volatile loss of plasticizer also leads to inconsistent product results, dependent on the ambient conditions and time taken to cool. Melt-flow indexes can vary greatly
  • Slot dies produce a tape for extrusion, and does not form a pellet for reprocessing.
  • Air cooling is preferred when compared to a traditional water bath as described. It is, however, possible to cool the extrudate with fan-assisted air supported on a moving conveyor.
  • the extrudate strand leaves the strand die at 165°C to 200°C and reaches a stand pelletizer at a maximum temperature of 60°C.
  • the plasticizer evaporation described above occurs on this moving conveyor. This reduction in mass results in financial loss, in addition to having an adverse effect on the melt-flow index.
  • a new method of cooling of the extrudate has therefore been developed to cope with the improved polymer composition.
  • the new method may be referred to as a chilled roller method
  • the polymer is extruded without additional venting in the barrel, and without a slot or strand die.
  • the barrel vents steam and produces an extrudate which is (1) irregular and inconsistent in size and shape, and (2) very low in water content, preferably below 1% (v/v).
  • This is a significant difference to a conventional process in which the polymer is extruded into a slot or strand die.
  • Slot or strand die methods require the extrudate to have a regular and consistent size and shape to remain operational, and since the presence of steam in the barrel causes the irregularities, the additional venting to the barrel must be provided for slot or strand die methods.
  • Irregular extrudate is permitted to fall onto a chilled roller or conveyor, where the temperature chills the extrudate quickly to below I00°C but above 10°C, and preferably below 60°C.
  • the chilling process is near instantaneous, occurring in less than 30s, more preferably less than 20s, even more preferably less than 10s, and generally in less than 5s.
  • the chilled rollers are set to obtain instant cooling, to thereby avoid plasticizer loss.
  • the irregular extrudate, once chilled, was directed into a commercial polymer grinder to be made into granules, which can be stored for onward processing, typically via encapsulation into hermetically sealed vacuum bags.
  • Adapted calendaring with, preferably water-chilled, chilled rollers to accommodate an inconsistent extrudate permits fast cooling of the extrudate to 60°C and below. Additionally, the high heat transfer properties of PVA with at least 15% by weight of hygroscopic salts results in further improved cooling via this system.
  • plasticizer becomes locked into the polymer composition, being below the plasticizer evaporation temperature, preventing losses of the total weight of the polymer composition in the range of 0.75% to 1.25% due to evaporation.
  • the resulting polymer also has a very low water content, as most of the water present is lost during the extrusion process as steam. Water content can then be maintained below 1% by weight which is the maximum possible water content required for successful reprocessing of the irregular extrudate. This also removes the need for a further polymer drying step.
  • the chilled roller method results in an extrudate which has a higher melt- flow index under otherwise identical conditions.
  • extrudate temperature is consistently lower at the point of reaching the granulator in embodiments of the chilled roller method, thus reducing plasticizer evaporation.
  • the irregular extrudate once chilled, can then be directed into a commercial polymer grinder or granulator, and the polymer ground until the particulate matter falls through a sieve plate to determine maximum particulate size.
  • the irregularity of the extrudate however creates a variable polymer grain size, typically in the range of 2mm to 4mm.
  • this non-uniformity of particular size aids polymer melt during subsequent reprocessing.
  • the combination of the chilled roller method is highly suited towards use with a granulator. Smaller particles melt more quickly, requiring less energy, with an observable 10°C reduction in barrel zone temperatures when compared with a strand die pellet process. Lower processing temperatures also result in lower plasticizer loss rates, which might otherwise turn to gas and cause gassing during reprocessing, usually via injection molding or extrusion. Gassing can lead to burn marks on molding, and part rejection and mold contamination during processing, so reduction in gassing is a noticeable improvement.
  • Vegetable wax is typically used to impart humidity resistance to a polymer. Typically, 0.3% to 1.0% of glycerol mono stearate or a stearamide would be used as the vegetable was.
  • usage of vegetable wax during the melt process also has a disadvantageous effect of inducing “screw slip”. Screw slip is a situation when, during the melt process, the extruder machine or injection moulder is unable to convey molten material due to slipperiness of the polymer melt, with the vegetable wax coating the barrel as a lubricant.
  • wax content For PVA having no salt included, 0.3% wax content would typically be the maximum permissible amount due to screw slippage, though with small amounts of salts, higher wax content, up to 2% to 3% can be provided.
  • the addition of these vegetable waxes decreases water absorption of PVOH formulations with mono and di propylene glycol by as much as 50% when compared with formulations without salts.
  • irregularity of the particulate shape also advantageously results in a reduction of screw slip when formulating the polymer composition including amounts of vegetable wax that would typically be expected to result in screw slip.
  • the irregular size and shape of the granules prior to melt forms a mixture more gradually in the present invention, allowing for better adhesion during polymer transfer via the screw. This allows for a larger wax component to be added.
  • compositions of the present invention thus provide a melt-processable PVA containing polymer typically having a flexural modulus similar to other extrudable polymers.
  • This enables a soluble and biodegradable polymer to be used for the processing of a wide variety of articles without the processing problems experienced in the prior art, such as thermal degradation and high temperature cross-linking.
  • the known advantageous properties of PVA such as its high tensile strength and good barrier characteristics, are retained in the melt-processable composition, which may be extruded on current extrusion lines, blow-moulders and injection moulders without modification.

Landscapes

  • Mechanical Engineering (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Polymers & Plastics (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Health & Medical Sciences (AREA)
  • Organic Chemistry (AREA)
  • Compositions Of Macromolecular Compounds (AREA)
  • Processing And Handling Of Plastics And Other Materials For Molding In General (AREA)
  • Processes Of Treating Macromolecular Substances (AREA)
  • Paper (AREA)
  • Glanulating (AREA)

Abstract

L'invention concerne un procédé de création d'un polymère hydrosoluble traitable, le procédé comprenant les étapes consistant à : extruder une composition polymère hydrosoluble à partir d'un cylindre d'extrusion sans utiliser de filière, le cylindre d'extrusion n'étant pas ventilé autrement que par l'intermédiaire de sa sortie d'extrusion, pour produire un extrudat de polymère de forme irrégulière; à diriger l'extrudat de polymère de forme irrégulière sur un transporteur réfrigéré pour refroidir l'extrudat de polymère de forme irrégulière à une température inférieure à 60 °C; et à granuler l'extrudat de polymère de forme irrégulière pour former un granulé.
PCT/GB2021/051124 2020-05-26 2021-05-11 Procédé de production d'un polymère hydrosoluble, polymère hydrosoluble ainsi produit et composition polymère hydrosoluble traitable WO2021240130A1 (fr)

Priority Applications (7)

Application Number Priority Date Filing Date Title
EP21728272.2A EP4153392A1 (fr) 2020-05-26 2021-05-11 Procédé de production d'un polymère hydrosoluble, polymère hydrosoluble ainsi produit et composition polymère hydrosoluble traitable
AU2021279371A AU2021279371A1 (en) 2020-05-26 2021-05-11 Method of making a water-soluble polymer, water-soluble polymer so produced, and melt-processable water-soluble polymer composition
KR1020227044119A KR20230016192A (ko) 2020-05-26 2021-05-11 수용성 중합체의 제조 방법, 그에 의해 제조된 수용성 중합체, 및 용융-가공가능한 수용성 중합체 조성물
BR112022024229A BR112022024229A2 (pt) 2020-05-26 2021-05-11 Método para fazer um polímero solúvel em água, um polímero solúvel em água assim produzido e uma composição de polímero solúvel em água processável por fundição
JP2022573506A JP2023528600A (ja) 2020-05-26 2021-05-11 水溶性ポリマー組成物の製造方法
CN202180049541.1A CN115812026A (zh) 2020-05-26 2021-05-11 水溶性聚合物及其制作方法及可熔融加工的水溶性聚合物组合物
CA3184903A CA3184903A1 (fr) 2020-05-26 2021-05-11 Procede de production d'un polymere hydrosoluble, polymere hydrosoluble ainsi produit et composition polymere hydrosoluble traitable

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
GB2007826.7 2020-05-26
GB2007826.7A GB2595641A (en) 2020-05-26 2020-05-26 Method of making a water-soluble polymer composition
US16/882,794 2020-05-26
US16/882,794 US11718010B2 (en) 2020-05-26 2020-05-26 Method of making a water-soluble polymer composition

Publications (1)

Publication Number Publication Date
WO2021240130A1 true WO2021240130A1 (fr) 2021-12-02

Family

ID=76159678

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB2021/051124 WO2021240130A1 (fr) 2020-05-26 2021-05-11 Procédé de production d'un polymère hydrosoluble, polymère hydrosoluble ainsi produit et composition polymère hydrosoluble traitable

Country Status (8)

Country Link
EP (1) EP4153392A1 (fr)
JP (1) JP2023528600A (fr)
KR (1) KR20230016192A (fr)
CN (1) CN115812026A (fr)
AU (1) AU2021279371A1 (fr)
BR (1) BR112022024229A2 (fr)
CA (1) CA3184903A1 (fr)
WO (1) WO2021240130A1 (fr)

Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1112316B1 (fr) 1998-08-26 2004-03-10 Pvaxx Technologies Limited Compositions contenant du pval
US20090110942A1 (en) * 2004-10-18 2009-04-30 Rulande Henderson-Rutgers Barrier film
JP2012149144A (ja) * 2011-01-18 2012-08-09 Denki Kagaku Kogyo Kk ポリビニルアルコール樹脂及びその製造方法
JP2015214652A (ja) * 2014-05-12 2015-12-03 日本合成化学工業株式会社 ポリビニルアルコール系樹脂製ペレットの製法
JP2015214055A (ja) * 2014-05-09 2015-12-03 日本合成化学工業株式会社 ポリビニルアルコール系樹脂成形体の製法
JP2015214651A (ja) * 2014-05-12 2015-12-03 日本合成化学工業株式会社 ポリビニルアルコール系樹脂製ペレットの製法
US20170369693A1 (en) * 2013-03-25 2017-12-28 Peter Morris Research And Development Limited Water-soluble polymer and polymer internal lubricant
EP3348604A1 (fr) * 2015-09-11 2018-07-18 The Nippon Synthetic Chemical Industry Co., Ltd. Film hydrosoluble et corps d'emballage de produit chimique
EP3348608A1 (fr) * 2015-09-11 2018-07-18 The Nippon Synthetic Chemical Industry Co., Ltd. Film soluble dans l'eau, emballage pharmaceutique, et procédé de production d'un film soluble dans l'eau
US20180245028A1 (en) * 2015-09-11 2018-08-30 The Nippon Synthetic Chemical Industry Co., Ltd. Water-soluble film, chemical agent package and water-soluble film production method
US20200063076A1 (en) * 2017-06-12 2020-02-27 Mitsubishi Chemical Corporation Water-soluble film, chemical agent package, and method of producing water-soluble film

Patent Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1112316B1 (fr) 1998-08-26 2004-03-10 Pvaxx Technologies Limited Compositions contenant du pval
US20090110942A1 (en) * 2004-10-18 2009-04-30 Rulande Henderson-Rutgers Barrier film
JP2012149144A (ja) * 2011-01-18 2012-08-09 Denki Kagaku Kogyo Kk ポリビニルアルコール樹脂及びその製造方法
US20170369693A1 (en) * 2013-03-25 2017-12-28 Peter Morris Research And Development Limited Water-soluble polymer and polymer internal lubricant
JP2015214055A (ja) * 2014-05-09 2015-12-03 日本合成化学工業株式会社 ポリビニルアルコール系樹脂成形体の製法
JP2015214652A (ja) * 2014-05-12 2015-12-03 日本合成化学工業株式会社 ポリビニルアルコール系樹脂製ペレットの製法
JP2015214651A (ja) * 2014-05-12 2015-12-03 日本合成化学工業株式会社 ポリビニルアルコール系樹脂製ペレットの製法
EP3348604A1 (fr) * 2015-09-11 2018-07-18 The Nippon Synthetic Chemical Industry Co., Ltd. Film hydrosoluble et corps d'emballage de produit chimique
EP3348608A1 (fr) * 2015-09-11 2018-07-18 The Nippon Synthetic Chemical Industry Co., Ltd. Film soluble dans l'eau, emballage pharmaceutique, et procédé de production d'un film soluble dans l'eau
US20180245028A1 (en) * 2015-09-11 2018-08-30 The Nippon Synthetic Chemical Industry Co., Ltd. Water-soluble film, chemical agent package and water-soluble film production method
US20200063076A1 (en) * 2017-06-12 2020-02-27 Mitsubishi Chemical Corporation Water-soluble film, chemical agent package, and method of producing water-soluble film

Also Published As

Publication number Publication date
CN115812026A (zh) 2023-03-17
AU2021279371A1 (en) 2023-02-02
CA3184903A1 (fr) 2021-12-02
KR20230016192A (ko) 2023-02-01
JP2023528600A (ja) 2023-07-05
EP4153392A1 (fr) 2023-03-29
BR112022024229A2 (pt) 2022-12-27

Similar Documents

Publication Publication Date Title
US10954373B2 (en) Water-soluble polymer and polymer internal lubricant
US7375146B2 (en) PVA-containing compositions
KR20030096324A (ko) 핵제 및 가소제를 사용한 폴리히드록시알카노에이트의 가공
HUT55813A (en) Polymere-based compositions containing decomposed starch
US20200283612A1 (en) Water-soluble polymer composition and method of making a water-soluble polymer composition
US11718010B2 (en) Method of making a water-soluble polymer composition
AU2021279371A1 (en) Method of making a water-soluble polymer, water-soluble polymer so produced, and melt-processable water-soluble polymer composition
US20080200597A1 (en) Pva-Containing Compositions
GB2595641A (en) Method of making a water-soluble polymer composition
JP3203233B2 (ja) 生分解性樹脂組成物および単層成形物
JP2021155629A (ja) 熱可塑性樹脂組成物及びその成形体
JP2000511208A (ja) 永久帯電防止性及び防曇性を持つポリオレフィン、その製造方法、並びにその使用
JPH11279271A (ja) 樹脂ペレットの製造方法
CN116444832A (zh) 一种易封口pbat膜的制备方法

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 21728272

Country of ref document: EP

Kind code of ref document: A1

ENP Entry into the national phase

Ref document number: 3184903

Country of ref document: CA

ENP Entry into the national phase

Ref document number: 2022573506

Country of ref document: JP

Kind code of ref document: A

REG Reference to national code

Ref country code: BR

Ref legal event code: B01A

Ref document number: 112022024229

Country of ref document: BR

ENP Entry into the national phase

Ref document number: 20227044119

Country of ref document: KR

Kind code of ref document: A

ENP Entry into the national phase

Ref document number: 112022024229

Country of ref document: BR

Kind code of ref document: A2

Effective date: 20221128

NENP Non-entry into the national phase

Ref country code: DE

ENP Entry into the national phase

Ref document number: 2021728272

Country of ref document: EP

Effective date: 20221222

ENP Entry into the national phase

Ref document number: 2021279371

Country of ref document: AU

Date of ref document: 20210511

Kind code of ref document: A