WO2021220070A1 - Procédé de quantification de la teneur en polymères superabsorbants (sap) dans des produits sanitaires absorbants - Google Patents

Procédé de quantification de la teneur en polymères superabsorbants (sap) dans des produits sanitaires absorbants Download PDF

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Publication number
WO2021220070A1
WO2021220070A1 PCT/IB2021/052307 IB2021052307W WO2021220070A1 WO 2021220070 A1 WO2021220070 A1 WO 2021220070A1 IB 2021052307 W IB2021052307 W IB 2021052307W WO 2021220070 A1 WO2021220070 A1 WO 2021220070A1
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sap
sample
solid fraction
weight
fraction
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PCT/IB2021/052307
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English (en)
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Tonino CARUSO
Laura PALOMBI
Nicola D'alessio
Melania MIGLIACCIO
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Fater S.P.A.
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Publication of WO2021220070A1 publication Critical patent/WO2021220070A1/fr

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/44—Resins; Plastics; Rubber; Leather
    • G01N33/442—Resins; Plastics
    • 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
    • C08J11/00—Recovery or working-up of waste materials
    • C08J11/02—Recovery or working-up of waste materials of solvents, plasticisers or unreacted monomers
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N5/00—Analysing materials by weighing, e.g. weighing small particles separated from a gas or liquid
    • 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
    • C08J2333/00—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 only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Derivatives of such polymers
    • C08J2333/02—Homopolymers or copolymers of acids; Metal or ammonium salts thereof

Definitions

  • the present description relates to methods for measuring the quantity of super absorbent polymers (SAP) in samples derived from absorbent sanitary products.
  • SAP super absorbent polymers
  • Absorbent hygiene sanitary products are generally composed of different materials, including, for example, plastic film, cellulose fluff, and superabsorbent polymers (SAP). These sanitary products, therefore, contain fractions of precious materials whose recovery for reuse on the market is a decidedly desirable objective; the value and intended use for convenient recycling of the different fractions largely depends on the components recovered.
  • SAP super absorbent polymers
  • backbone basic structure
  • LPA linear polyacrylate
  • CLP A cross-linked linear polyacrylate
  • the polymeric network that is formed has negatively charged carboxylated groups (-COO ), which, due to electrostatic repulsions, can expand thus providing spaces inside that can absorb (and retain) more or less large volumes of water or aqueous solutions (hence the definition “absorbent gelling material”, AGM).
  • Cross-linking is also essential in order to render the copolymer insoluble in an aqueous environment.
  • the present description aims to provide a sensitive and reproducible method for measuring the quantity of super absorbent polymers (SAP), both in samples of virgin absorbent sanitary products, for example, during production steps of the these products, and in samples derived from post-consumer sanitary products, which have been, preferably, subjected to treatments that include, for example, the sterilization and separation of the various components of cellulose, plastic, and SAP.
  • SAP super absorbent polymers
  • the present description provides a method for measuring the quantity of super absorbent polymers (SAP) in a sample obtained from absorbent sanitary products that comprises at least one portion of a portion of cellulose and/or a portion of plastic in addition to a portion of SAP,
  • SAP contained in said sample comprise polymers of linear polyacrylate (LPA) and/or polymers of cross-linked polyacrylate (CLP A).
  • the method comprises the steps of: a) placing a first aliquot of the sample in a solution comprising hydrogen peroxide, and obtaining a suspension comprising a solid fraction SFi and a liquid fraction LFi, b) after a period of time Ti, separating said solid fraction SFi from said liquid fraction LFi, wherein said liquid fraction LFi comprises the portion of SAP made soluble by said aqueous solution comprising hydrogen peroxide, and said solid fraction SFi comprises at least one of said cellulose portion and/or said plastic portion, c) weighing said solid fraction SFi, d) calculating the quantity of SAP contained in said sample as a function of the weight of said first aliquot of the sample and the weight of said solid fraction SFi.
  • the solution comprising hydrogen peroxide of said step a) has a temperature between 65°C and 100°C, preferably between 80°C and 100°C.
  • the first aliquot of the sample of said step a) is dried.
  • the method comprises the step of drying the solid fraction SFi separated in said step b); in one or more embodiments, said step c) of weighing is carried out on said dried solid fraction SFi.
  • the quantity of SAP may be calculated as a function of the difference between the weight of the first aliquot of the sample and the weight of said solid fraction SFi.
  • the method may, furthermore, comprise the steps of: e) placing a second aliquot of the sample into a solution comprising at least one acid, preferably hydrochloric acid (HC1), and obtaining a suspension comprising a solid fraction SF2 and a liquid fraction LF2, f) after a period of time T2, separating said solid fraction SF2 from said liquid fraction LF2, wherein said solid fraction SF2 comprises the SAP portion and at least one of said cellulose portion and/or said plastic portion, i) weighing said solid fraction SF2,
  • HC1 hydrochloric acid
  • the solution comprising an acid of said step e) has a temperature comprised between 65°C and 100°C, preferably between 80°C and 100°C.
  • the method comprises the step of drying the solid fraction SF2 separated in said step f); in one or more embodiments, said step i) of weighing is carried out on said dried solid fraction SF2.
  • FIG. 1 represents the main components of the SAP and their three-dimensional structure (image extracted and modified from: BASF Superabsorbents, SAP website: www.superabsorbents.basf.com/home):
  • FIG. 2 represents the molecular mechanism underlying the swelling of the SAP when placed in aqueous solution (image extracted and modified from: M.J. Zohuriaan- Mehr, K. Kabiri, Superabsorbent Polymer Materials: A Review, Egyptian Polymer Journal 17 (6), 2008, 451-477);
  • absorbent sanitary products generally refers to disposable absorbent products, such as diapers for babies, incontinence pads for adults, sanitary towels, bed linings, etc. These absorbent products can comprise plastic, super-absorbent polymers, cellulose or even only plastic and super-absorbent polymers.
  • absorbent performance of absorbent sanitary products is determined by the quantity of SAP they contain; it is of fundamental importance to be able to quantify the content of the SAP in the production and quality control steps of the manufactured products.
  • methods are known to date for treating post-consumer absorbent sanitary products in order to obtain the separation of the various components, such as for example cellulose, plastic, super-absorbent polymers (SAP).
  • a method known to date for treating and separating the different components (or fractions or portions) of post-consumer absorbent sanitary products may comprise the steps described, for example, in the document WO 2018/060827 by the same Applicant.
  • This method may comprise the step of sterilizing the post-consumer absorbent sanitary products, of shredding the sterilized products, drying the sterilized and shredded products, and separating the sterilized, shredded and dried products into the plastic, cellulose, and SAP portions.
  • SAP are generally prepared by the copolymerization of one or more monomers (acrylic acid, sodium or potassium acrylate, and/or acrylamide; Liu M., Guo T. 2001. Preparation and swelling properties of crosslinked sodium polyacrylate. Journal of Applied Polymer Science 82: 1515-1520).
  • these monomers give rise to the basic structure (backbone) of the material, or rather, a linear polyacrylate (LPA) with a bifunctional crosslinker (generally N,N-methylene-bis-acrylamide (MBA), Ethylene glycol dimethacrylate (EGDMA), Diallyl phthalate (DP), or Triethylene glycol dimethacrylate (TEGDMA)).
  • the result is a copolymer based on crosslinked linear polyacrylate (CLP A), which has a degree of cross-linking depending on the quantity of cross-linking compound used.
  • CLP A crosslinked linear polyacrylate
  • the polymeric network that is formed has negatively charged carboxylated groups (-COO ), which, due to electrostatic repulsions, can expand, thus providing spaces inside the lattice that can absorb (and retain) more or less large volumes of water or aqueous solutions (hence the definition “absorbent gelling material”, AGM).
  • Cross-linking is also essential in order to render the copolymer insoluble in an aqueous environment.
  • Methods known to date for treating absorbent sanitary products that include the sterilization and separation of the different fractions - i.e. the cellulose fraction, the plastic fraction, and the SAP fraction - may comprise steps wherein the post-consumer sanitary products (for example, used diapers), as well as being sterilized, are subjected to treatments with oxidizing compounds, for example, hydrogen peroxide, persulfate, peroxy-monosulfate and/or ozone, to achieve, for example, decontamination from chemical compounds also derived from human metabolism.
  • oxidizing compounds for example, hydrogen peroxide, persulfate, peroxy-monosulfate and/or ozone
  • post-consumer sanitary products may comprise salts and ionic compounds (not present in a virgin material) and which are capable of significantly altering the absorbent capacity of SAP.
  • the present description therefore provides a method for measuring the quantity of super absorbent polymers (SAP) in a sample derived from absorbent sanitary products comprising at least one portion of a portion of cellulose and/or a portion of plastic in addition to a portion of SAP, wherein the SAP contained in said sample comprise polymers of linear polyacrylate (LPA) and/or polymers of cross-linked polyacrylate (CLP A), the method comprising the steps of: a) placing a first aliquot of the sample in a solution comprising hydrogen peroxide and obtaining a suspension comprising a solid fraction SFi and a liquid fraction LFi, b) after a period of time Ti, separating said solid fraction SFi from said liquid fraction LFi, wherein said solid fraction SFi comprises at least one of said cellulose portion and/or said plastic portion, c) weighing said solid fraction SFi, d) calculating the quantity of SAP contained in said sample as a function of the weight of said first aliquot of the sample and the weight of said solid fraction SFi.
  • the step of placing a first aliquot of the sample into a solution comprising hydrogen peroxide of said step a) is carried out at a temperature comprised between 65°C and 100°C, preferably between 80°C and 100°C.
  • the first aliquot of the sample supplied in said step a) is dried.
  • the method comprises the step of drying the solid fraction SFi separated in said step b); in one or more embodiments, said step c) of weighing is carried out on said dried solid fraction SFi.
  • said time period Ti is between 20 minutes and 90 minutes, preferably between 30 minutes and 60 minutes.
  • the solution comprising said first fraction of the sample is kept under stirring.
  • said solution comprising hydrogen peroxide is an aqueous solution, preferably comprising hydrogen peroxide in a quantity by weight comprised between 5% and 33%, preferably comprised between 8% and 15% of the solution.
  • the solution comprising hydrogen peroxide may further comprise at least one salt of a metal, preferably selected from sodium chloride, potassium chloride, sodium sulphate, potassium sulphate, and ferrous sulphate.
  • a metal preferably selected from sodium chloride, potassium chloride, sodium sulphate, potassium sulphate, and ferrous sulphate.
  • the solution comprising hydrogen peroxide may comprise NaCl and/or KiSCL .
  • the solution comprising hydrogen peroxide may comprise NaCl in an quantity ranging from 0.2% to 1.0%, preferably equal to 0.5% by weight of the solution and/or K 2 SO 4 in a quantity comprised between 0.2% and 1.0%, preferably equal to 0.5% by weight of the solution.
  • FeSCE may be used in a quantity ranging from 0.001% to 0.01%, preferably equal to 0.005% by weight of the solution. The addition of these salts reproduces the conditions of the post-consumer samples, and thus makes it possible to check whether the virgin material is already partially or completely undergoing solubilization reactions.
  • iron (II) in the form of FeSCE reproduces a catalytic effect on hydrogen peroxide, present in post consumer samples, where iron may be present in a quantity between 50-100 ppm. In fact, iron (II) accelerates the oxidizing action of hydrogen peroxide (as described in US 5,525,008).
  • the pH of the aqueous solution comprising an acid may be comprised between 0.7 and 3.0.
  • the quantity of SAP may be calculated as a function of the difference between the weight of the first aliquot of the sample and the weight of said solid fraction SFi.
  • the solid portion will comprise at least one of the cellulose portion (CE) and/or the plastic portion (PO) since the SAP, made soluble by said aqueous solution comprising hydrogen peroxide will be passed into the liquid fraction LFi.
  • the method may, furthermore, comprise the steps of: e) placing a second aliquot of the sample into a solution comprising at least one acid, preferably hydrochloric acid (HC1), and obtaining a suspension comprising a solid fraction SF2 and a liquid fraction LF2, f) after a period of time T2; separating said solid fraction SF2 from said liquid fraction LF2, wherein said liquid fraction LF2 comprises any contaminants contained in said sample and made soluble by said solution comprising at least one acid, and said solid fraction SF2 comprises the SAP portion and at least one of said cellulose portion and/or said plastic portion, g) weighing said solid fraction SF2, h) calculating the quantity of SAP, free of any said contaminants, contained in said sample as a function of the difference in weight of said solid fraction SF2 and of said solid fraction SFi.
  • the solution comprising at least one acid of said step e) has a temperature comprised between 65°C and 100°C, preferably between 80°C and 100°C.
  • the second sample aliquot of said step e) is a dried aliquot.
  • the method comprises the step of drying the solid fraction SF2 separated in said step f); in one or more embodiments, said weighing step g) is carried out on said dried solid fraction SF2.
  • said time period T2 is between 20 minutes and 90 minutes, preferably between 30 minutes and 60 minutes.
  • the aqueous solution comprising said second fraction of the sample is kept under stirring.
  • said drying steps are carried out at a temperature between 60°C and 110°C, preferably between 75°C and 95°C.
  • the method also comprises steps b’) and f ) of washing said solid fraction SFi and said solid fraction SF2 before steps c) and g).
  • This washing step can be carried out by using water at a temperature between 50°C and 90°C.
  • said step b) and said step f) of separating said solid fraction and said liquid fraction may be carried out by filtration in a collection device, for example, through a funnel with paper filter.
  • the sample obtained from absorbent sanitary products may be a virgin sample.
  • the sample may also be a sample derived from post-consumer absorbent sanitary products. This sample may comprise at least one of a cellulose portion and/or a plastic portion as well as a portion of SAP and mixtures thereof.
  • the sample to be analyzed may comprise, in its entirety, a mixture of solids of initial mass m° , composed of cellulose CE, of superabsorbent polymers SAP, and plastic comprising polyolefins PO.
  • the sample may also comprise contaminants (f contaminants), and which step e) of the method allows them to be brought into the liquid fraction LF2 and to subtract them from the calculation of the total quantity of SAP.
  • the contaminants may derive from treatments carried out for the quality control of the product and may, for example, comprise sodium or potassium chlorides and sulphates.
  • these contaminants may comprise saline and organic compounds, soluble residues of a pOSt-metabolic nature (/contaminants).
  • the total mass of the sample may be given by the sum of the different contributions: total maSS CE PO SAP /contaminants
  • Step a) of placing a first aliquot of the sample into a solution, preferably aqueous, comprising hydrogen peroxide and having a temperature between 65°C and 100°C allows both the fraction of any contaminants (/contaminants) and the decomposed SAP component to be brought into solution, and made soluble by treatment with hot hydrogen peroxide.
  • the solid fraction SFi (separated from the liquid fraction LFi) comprises only the solid fractions not passed in solution, i.e. the cellulose component and/or the plastic component containing polyolefins (CE and/or PO), which have not been modified by contact with hydrogen peroxide.
  • the SAP content may be calculated as a function of the difference between the weight of the first aliquot of the sample and the weight of the solid fraction SFi.
  • the preferably aqueous solution used in step e) comprising at least one acid may comprise at least one acid selected from hydrochloric acid (HC1), perchloric acid (HCIO4), or phosphoric acid (H3PO4), preferably hydrochloric acid (HC1), in a concentration ranging from 0.001 M and 0.2 M, preferably between 0.01 M and 0.10 M.
  • This solution may further comprise at least one salt, preferably NaCl and/or K2SO4 NaCl may be comprised in a quantity between 0.2% and 1.0%, preferably equal to 0.5% by weight of the aqueous solution.
  • K2SO4 may be comprised in a quantity between 0.2% and 1.0%, preferably equal to 0.5% by weight of the aqueous solution.
  • Step e) of placing said second aliquot of the sample in a solution comprising at least one acid, preferably HC1, more preferably at a temperature between 65°C and 100°C, allows appreciating (in the case of virgin samples) the contribution by weight of any contaminants that may have been introduced into the sample during quality control steps of the product (for example salts, such as sodium chloride, contained in synthetic urine solutions).
  • this step e) makes it possible to appreciate the contribution by weight of: salts such as chlorides, sulphates, and nitrates of sodium, ammonium, potassium, and organic residues comprising urea, creatinine and carboxylates derived from metabolism.
  • salts such as chlorides, sulphates, and nitrates of sodium, ammonium, potassium, and organic residues comprising urea, creatinine and carboxylates derived from metabolism.
  • the solid fraction SF 2 (separated from the liquid fraction LF 2 ) comprises the solid components (CE and/or PO + SAP), which have not passed into the liquid phase.
  • This solid fraction SF 2 comprises the SAP portion and at least one of said cellulose portion and/or said plastic portion, and is free of contaminants contained in said sample and made soluble by said solution comprising at least one acid.
  • the weight of the SAP contained in the sample can, therefore, be calculated as a function of the difference between the weight of the fraction FR 2 and the weight of the fraction FRi.
  • the contribution by weight of the SAP component alone is, therefore, obtained by calculating the difference between the weight of the solid fraction FR 2 (which indicates the weight of the solid components SAP+CE and/or PO) and the weight of the solid fraction FRi (which indicates the weight of the two solid components CE and/or PO):
  • the quantity of the component based on virgin cellulose only (CE) that can be recovered in the hot hydrogen peroxide treatment step (H 2 O 2 ) in aqueous saline medium is greater than 99% by mass (there are minimal losses of this component during the step of separating the liquid fraction from the solid fraction, for example, by filtration);
  • the quantity of the component based on virgin plastic only (PO) that can be recovered in the hot hydrogen peroxide treatment step (H 2 O 2 ) in aqueous saline medium is greater than 99% by mass (there are minimal losses of this component during the step of separating the liquid fraction from the solid fraction, for example by filtration);
  • the quantity of the component based on virgin cellulose only (CE) that can be recovered in the step of treating with the acidic saline aqueous solution is greater than 99% by mass (there are minimal losses of this component during the step of separating the liquid fraction from the solid fraction, for example, by filtration);
  • the quantity of the component based on virgin plastic only (PO) that can be recovered in the step of treating with the acidic saline aqueous solution is greater than 99% by mass (there are minimal losses of this component during the step of separating the liquid fraction from the solid fraction, for example, by filtration);
  • the quantity of component based on only virgin SAP treated an acidic saline aqueous solution (for example, comprising 0.1 M HC1, 0.5% NaCl by weight, 0.5% K2SO4 by weight) that can be recovered is greater than 99% by mass (losses due only to the filtration process).
  • Step 1 Three distinct fractions of virgin cellulose (CE), plastic (PO) and SAP were homogenized by dimension reduction of the size (according to the UNI 10802: 2013 Method) to fragments of sizes between 2 and 3 cm, dried at a temperature of 110°C up to constant weight (IRSA-CNR 1984 Method), weighed and placed - separately - in suspension in an aqueous solution at a temperature between 65°C and 100°C comprising 10% hydrogen peroxide by weight, w/w (density at 20°C 1.03 g/ml), 0.5% NaCl by weight, 0.5% K2SO4 by weight, 0.005% FeSCE by weight.
  • the liquid/solid ratio (L/S, ml/g) between the volume of the liquid component of the aqueous solution and the weight of the solid component of the sample was equal to 25.
  • the solid fraction was separated from the liquid fraction by hot filtration on a pre-weighed Whatman Grade 1 paper filter.
  • the solid fraction retained by the filter was subjected to a washing step, repeated three times, with water at a temperature between 65°C and 100°C. No significant precipitates are evident in the liquid fraction brought to room temperature.
  • the solid fraction was dried at a temperature of 100°C to constant weight (IRSA-CNR 1984 Method).
  • the solid fraction was weighed (net of the filter tare) and the weight recovery of the CE, PO or SAP fractions was calculated, knowing the initial weight of each fraction of virgin material.
  • Step 2 Three distinct fractions of virgin cellulose (CE), plastic (PO) and SAP were homogenized by dimension reduction of the size (according to the UNI 10802: 2013 Method) to fragments of sizes between 2 and 3 cm, dried at a temperature of 110°C up to constant weight (IRSA-CNR 1984 Method), weighed and placed - separately - in suspension in an aqueous solution at a temperature between 65°C and 100°C comprising 0.1 M HC1, 0.5% NaCl by weight, 0.5% K 2 SO 4 by weight.
  • the liquid/solid ratio (L/S, ml/g) between the volume of the liquid component of the aqueous solution and the weight of the solid component of the sample was equal to 25.
  • the solid fraction was separated from the liquid fraction by hot filtration on a pre-weighed Whatman Grade 1 paper filter.
  • the solid fraction retained by the filter was subjected to a washing step with water at a temperature between 65°C and 100°C. The washing step was repeated until the eluate showed a neutral pH.
  • the liquid fraction corresponding to the treatment of the SAP brought to room temperature may present precipitates, to be recovered after centrifugation at 3000 rpm for 20 minutes.
  • the overall solid fraction was dried at a temperature of 100°C to constant weight (IRSA-CNR 1984 Method). The solid fraction was weighed (net of the filter tare) and the weight recovery of the CE, PO or SAP fractions was calculated, knowing the initial weight of each fraction of virgin material.
  • Step 1 more than 99% in mass of CE and PO were recovered, and a quantity of less than 1% of SAP.
  • almost all the fraction comprising the SAP was solubilized in the presence of 0.5% NaCl by weight, 0.5% K 2 SO 4 by weight, 0.005% FeSCE by weight.
  • Step 2 more than 99% in mass of CE, PO and SAP were recovered.
  • the step of placing the virgin sample in contact with an aqueous solution comprising hot hydrochloric acid (at pH l), 0.5% NaCl by weight, 0.5% K2SO4 by weight, did not cause the decomposition of the different fractions (of CE, PO, SAP) into soluble derivatives.
  • Samples were used comprising CE, PO and SAP, which contain residual contaminations soluble in water and easily extractable in acid solutions, and which help to inactivate the absorbing capacity of the superabsorbent polymer.
  • the most abundant compounds found over 1% by weight are sodium or potassium chlorides and sulphates, as well as urea and ammonium.
  • a laboratory sample (about 30 g) was homogenized by size reduction of the particle size (according to the UNI 10802: 2013 Method) to fragments of between 2 and 3 cm.
  • the sample was dried at a temperature of 110°C.
  • the first aliquot and the second aliquot were placed in contact - respectively - with: i) an aqueous solution at a temperature of 90°C comprising hydrogen peroxide at 10% by weight, w/w (density 1.03 g/ml) and ii) an aqueous solution at a temperature of 90°C comprising 0.1 M HC1.
  • the sample undergoes a rapid whitening phenomenon, which is observed in a period of time between 5 minutes and 10 minutes.
  • the SAP fraction does not swell as it loses its absorbent capacity.
  • a clear separation of a solid fraction from a liquid fraction is observed; in particular, on the surface the CE and PO fractions separate and rise upwards.
  • the higher viscosity of the liquid causes, in the absence of continuous agitation, bubbles of vapor and oxygen which, trapped under the mass of CE/PO, push it up the reactor, causing overflow of the material, if the reactor is not of the right size in relation to what is subj ected to treatment therein, or with no agitation present or less than 180 rpm.
  • a suitable reactor has a volume greater than at least 100 times the treated mass.
  • the solid fraction is separated from the hot liquid fraction by pouring the solution onto a filter funnel with 1 mm holes and onto Whatman Grade 1 filter paper previously weighed and made to adhere moist to the flat bottom of a 500 ml Buchner funnel.
  • the filter funnel retains the whitened solid fraction that comprises CE and PO. Any precipitates are recovered after centrifugation of the solution at room temperature, to be carried out at least 3000 rpm for 15 minutes. Any traces of de-cross-linked SAP and hydrogen peroxide are eliminated from the solid fraction by washing this fraction contained in the filter three times, with about 250 ml of water at T>75°C.
  • the washed solid fraction is squeezed and dried at 100°C in an oven until constant weight (for at least 4 hours). The dried solid fraction is weighed; the dry weight will correspond to the weight of the CE and PO components.
  • any traces of salts and soluble residual compounds are eliminated by washing the solid fraction contained in the filter three times, with about 250 ml of water at T>75°C. A whitening effect is not achieved.
  • the liquid fraction brought to room temperature may present precipitates, to be recovered after centrifugation at 3000 rpm for 20 minutes.
  • the overall solid fraction is squeezed and dried at 100°C in an oven up to constant weight (IRSA-CNR 1984 Method). The dry weight will correspond to the weight of the components CE+SAP+PO.
  • the weight of the component comprising cellulose and plastic (CE+PO) is obtained from the first aliquot of the sample; the second aliquot gives the weight of the cellulose, SAP and plastic components (CE+PO+SAP).
  • the method shows a repeatability of the measurement within the percentage error of 1-2% and is also suitable for determining the residual percentage of PO in CE.
  • the dried portion comprising cellulose and plastic (CE+PO) can, in fact, be separated by density fractionation (for example, by means of US 2015/0238974A1, Liquid Density Separation System. Kenneth Chen-Ting Wang. Oxnard, CA, Juan Alvarez, Oxnard, CA (US) or by extraction in organic solvent (e.g. by UNIEN ISO 6427:2013, Plastics: Determination of matter extractable by organic solvents).
  • Optimal results in terms of duration of the method are obtained when the two aliquots of the sample are immersed in the respective hot solutions, preferably at a temperature not lower than 65°C, more preferably between 75°C and 100°C.

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Abstract

L'invention concerne un procédé de mesure de la quantité de polymères superabsorbants (SAP) dans un échantillon dérivé de produits sanitaires absorbants comprenant au moins une partie de cellulose et/ou une partie de matières plastiques en plus d'une partie de SAP. Le SAP contenu dans l'échantillon comprend des polymères de polyacrylate linéaire (LPA) et/ou des polymères de polyacrylate réticulé (CLP A), le procédé consistant : a) à placer une première aliquote de l'échantillon dans une solution aqueuse comprenant du peroxyde d'hydrogène et à obtenir une suspension comprenant une fraction solide SF1 et une fraction liquide LF1, b) après une période T1 à séparer ladite fraction solide SF1 de ladite fraction liquide LF1, ladite fraction liquide LF1 comprenant la partie de SAP rendue soluble par ladite solution aqueuse comprenant du peroxyde d'hydrogène, et ladite fraction solide SF1 comprend ladite partie de cellulose et/ou ladite partie de matières plastiques, c) à peser ladite fraction solide SF1, d) à calculer la quantité de SAP contenue dans ledit échantillon en fonction du poids de ladite première partie de l'échantillon et du poids de ladite fraction solide SF1.
PCT/IB2021/052307 2020-04-27 2021-03-19 Procédé de quantification de la teneur en polymères superabsorbants (sap) dans des produits sanitaires absorbants WO2021220070A1 (fr)

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IT102020000009085A IT202000009085A1 (it) 2020-04-27 2020-04-27 Procedimento per quantificare il contenuto di polimeri super assorbenti in prodotti sanitari assorbenti

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US20150045461A1 (en) * 2012-03-23 2015-02-12 National University Corporation Hokkaido University Method for reclaiming used superabsorbent polymer
US20150291762A1 (en) * 2012-07-06 2015-10-15 Nippon Paper Industries Co., Ltd. Recycled fiber and recycled fiber molding

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CN102393441A (zh) * 2011-11-15 2012-03-28 厦门柏润氟材料科技有限公司 高吸水性树脂和卫生用品中高吸水性树脂含量的测定方法
US20150045461A1 (en) * 2012-03-23 2015-02-12 National University Corporation Hokkaido University Method for reclaiming used superabsorbent polymer
US20150291762A1 (en) * 2012-07-06 2015-10-15 Nippon Paper Industries Co., Ltd. Recycled fiber and recycled fiber molding

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