CN106680275B

CN106680275B - Method for analyzing polyurethane in polyvinyl chloride system

Info

Publication number: CN106680275B
Application number: CN201611214449.3A
Authority: CN
Inventors: 叶菲菲; 侯小刚; 赵彬希; 贾梦虹; 杨玲玲
Original assignee: Shanghai Microspectrum Chemical Technology Service Co Ltd
Current assignee: Shanghai Microspectrum Testing Technology Group Co ltd
Priority date: 2016-12-26
Filing date: 2016-12-26
Publication date: 2019-12-17
Anticipated expiration: 2036-12-26
Also published as: CN106680275A

Abstract

The invention provides an analysis method of polyurethane in a polyvinyl chloride system, which comprises the steps of dissolving a polyvinyl chloride resin sample containing polyurethane in an organic solvent, adding a degradation agent and a degradation assistant to enable the polyurethane to be monomeric to obtain a decomposition product containing polyol and oligomer for layering, concentrating and drying a lower layer solution, adding ethanol, stirring and separating a soluble component and an insoluble component, then adding toluene diisocyanate and a chain extender 1, 4-butanediol into the soluble component for polymerization reaction to obtain the polyurethane, finally carrying out infrared detection on the insoluble component and the polyurethane, and carrying out GC-MS detection on a degradation solution.

Description

Method for analyzing polyurethane in polyvinyl chloride system

Technical Field

The invention belongs to an analysis method of polyurethane in a polyvinyl chloride system, and particularly relates to separation and analysis of polyvinyl chloride and polyurethane in polyvinyl chloride resin.

Background

polyvinyl chloride (PVC) is a general-purpose resin with excellent performance and low price, but has the defects of large brittleness, poor thermal stability, poor processability and the like, and needs to be modified. The high-performance PVC composite material can be obtained by blending, toughening and modifying PVC by using a thermoplastic polyurethane elastomer (TPU).

the TPU can obviously improve the thermal stability of the PVC, improve the thermal decomposition temperature of the PVC, improve the mixing time and the stabilization time of the PVC on a plasticator, and improve the processing fluidity of the PVC. The addition of TPU is shown through the microscopic morphology characteristics of the composite material, so that the PVC matrix generates brittle-tough transition, and the toughness of the material is improved.

For the samples of simple physical blending (no shearing force) of PVC/TPU, the difference in solubility can be distinguished, and for the samples of PVC/TPU which are mechanically blended (such as an extruder and an open mill), the difference in solubility cannot be separated, because TPU is entangled with PVC during toughening, resulting in a small difference in solubility between PVC and TPU.

In addition, TPU is decomposed by a chemical method and then separated from PVC, but the decomposition of TPU needs to be completed under the conditions of high temperature (200-320 ℃) and high pressure, and polyvinyl chloride has poor thermal stability and starts to decompose at 170 ℃.

In view of the above problems, a method for separating and analyzing TPU and PVC in a PVC system under relatively mild conditions is provided.

Disclosure of Invention

in order to solve the above problems, the present invention provides a method for analyzing polyurethane in a polyvinyl chloride system, comprising the steps of:

(1) dissolving: dissolving a polyvinyl chloride resin sample containing polyurethane in an organic solvent;

(2) And (3) decomposition: adding a degradation agent and a degradation assistant agent into the step (1) to enable polyurethane to be monomeric to obtain a decomposition product containing polyol and oligomer;

(3) Separation: layering the solution in the step (2), concentrating and drying the lower layer solution, adding ethanol, stirring, and separating soluble components and insoluble components in the solution;

(4) Polymerization: concentrating and drying the upper layer solution in the step (3), adding DMAC (dimethylacetamide), toluene diisocyanate and a chain extender 1, 4-butanediol, and carrying out polymerization reaction to obtain polyurethane;

(5) and (3) detection: drying the insoluble components in the step (3) and the polyurethane in the step (4) and then carrying out infrared detection; and (4) carrying out GC-MS detection on the soluble component in the step (3).

In one embodiment, the organic solvent in step (1) is one or more of N-methylpyrrolidone and cyclohexanone.

in one embodiment, the degradation agent is one or more of ethylene glycol, diethylene glycol, propylene glycol, 1, 3-propanediol, 1, 2-propanediol, dipropylene glycol, 1, 4-butanediol, 1, 5-pentanediol, 1, 6-hexanediol, polyoxyethylene glycol, polyoxypropylene glycol, polyethylene glycol, and dialkyl phosphate.

In one embodiment, the degradation aid is one or more of diethanolamine, triethanolamine, and alkaline earth metal stearate.

in one embodiment, the degradation aid alkaline earth metal stearate is calcium stearate and/or magnesium stearate.

In one embodiment, the decomposition in step (1) is carried out at a reaction temperature of 100 to 170 ℃.

in one embodiment, the weight ratio of the sample of polyurethane-containing polyvinyl chloride resin to the degrading agent is 1: (0.04-0.4).

In one embodiment, the weight ratio of the degrading agent to co-degrading agent is 1: (0.1-0.3).

In one embodiment, the weight ratio of the degrading agent to co-degrading agent is 1: (0.1-0.2).

In one embodiment, the detection conditions for the GC-MS are: temperature rising procedure: maintaining at 70 deg.C for 1min, raising temperature to 280 deg.C at 20 deg.C/min, and maintaining for 8.5 min; CD-5 MS column: 30 m.times.0.25 mm.times.0.25 μm; the carrier gas is helium (with the purity of 99.999 percent) and the flow rate is 1.0 mL/min; injecting sample without shunting, wherein the temperature of a sample injection port is 250 ℃, and the sample injection amount is 1 mu L; electron impact ion source (EI source) with electron impact energy of 70 eV; the transmission line temperature is 280 ℃; the ion source temperature is 250 ℃; the solvent delay time is 3.5 min; a full SCAN and a selective ion mode (SCAN/SIM), the SCAN range is 40-400 amu.

The above-described and other features, aspects, and advantages of the present application will become more apparent with reference to the following detailed description.

Drawings

FIG. 1 Infrared Spectroscopy of polyvinyl chloride in example 2

FIG. 2 Infrared Spectrum of polyurethane in example 2

Detailed Description

The disclosure may be understood more readily by reference to the following detailed description of preferred embodiments of the invention and the examples included therein. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In case of conflict, the present specification, including definitions, will control.

The term "prepared from …" as used herein is synonymous with "comprising". The terms "comprises," "comprising," "includes," "including," "has," "having," "contains," "containing," or any other variation thereof, as used herein, are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, process, method, article, or apparatus.

The conjunction "consisting of …" excludes any unspecified elements, steps or components. If used in a claim, the phrase is intended to claim as closed, meaning that it does not contain materials other than those described, except for the conventional impurities associated therewith. When the phrase "consisting of …" appears in a clause of the subject matter of the claims rather than immediately after the subject matter, it defines only the elements described in the clause; other elements are not excluded from the claims as a whole.

When an amount, concentration, or other value or parameter is expressed as a range, preferred range, or as a range of upper preferable values and lower preferable values, this is to be understood as specifically disclosing all ranges formed from any pair of any upper range limit or preferred value and any lower range limit or preferred value, regardless of whether ranges are separately disclosed. For example, when a range of "1 to 5" is disclosed, the described range should be interpreted to include the ranges "1 to 4", "1 to 3", "1 to 2 and 4 to 5", "1 to 3 and 5", and the like. When a range of values is described herein, unless otherwise stated, the range is intended to include the endpoints thereof and all integers and fractions within the range.

The singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise. "optional" or "any" means that the subsequently described event or events may or may not occur, and that the description includes instances where the event occurs and instances where it does not.

Approximating language, as used herein throughout the specification and claims, is intended to modify a quantity, such that the invention is not limited to the specific quantity, but includes portions that are literally received for modification without substantial change in the basic function to which the invention is related. Accordingly, the use of "about" to modify a numerical value means that the invention is not limited to the precise value. In some instances, the approximating language may correspond to the precision of an instrument for measuring the value. In the present description and claims, range limitations may be combined and/or interchanged, including all sub-ranges contained therein if not otherwise stated.

In addition, the indefinite articles "a" and "an" preceding an element or component of the invention are not intended to limit the number requirement (i.e., the number of occurrences) of the element or component. Thus, "a" or "an" should be read to include one or at least one, and the singular form of an element or component also includes the plural unless the stated number clearly indicates that the singular form is intended.

"Polymer" means a polymeric compound prepared by polymerizing monomers of the same or different types. The generic term "polymer" embraces the terms "homopolymer", "copolymer", "terpolymer" and "interpolymer".

"interpolymer" means a polymer prepared by polymerizing at least two different monomers. The generic term "interpolymer" includes the term "copolymer" (which is generally used to refer to polymers prepared from two different monomers) and the term "terpolymer" (which is generally used to refer to polymers prepared from three different monomers). It also includes polymers made by polymerizing more monomers. "blend" means a polymer formed by two or more polymers being mixed together by physical or chemical means.

The invention provides an analysis method of polyurethane in a polyvinyl chloride system, which comprises the following steps:

(5) and (3) detection: drying the insoluble components in the step (3) and the polyurethane in the step (4) and then carrying out infrared detection; and (3) carrying out GC-MS detection on the decomposition liquid in the step (1).

Polyvinyl chloride is a high molecular material using one chlorine atom instead of one hydrogen atom in polyethylene, and is an amorphous polymer containing a small amount of crystalline structure. PVC is a linear polymer of mostly head-to-tail structures of VCM monomers. The carbon atoms are arranged in a zigzag pattern, all atoms being connected by sigma bonds. All carbon atoms being sp³Hybridization is carried out. Short syndiotactic stereoregular structures are present in the PVC molecular chain. As the polymerization temperature decreases, the syndiotactic tacticity increases. The polyvinyl chloride macromolecular structure has the defects of poor heat deformation resistance, poor aging resistance and the like due to unstable structures such as a head structure, a branched chain, double bonds, allyl chloride, tertiary chloride and the like.

Polyvinyl chloride is one of the most thermally sensitive polymers in industry, and is prone to thermal degradation. In order to improve the thermal processing stability and thermal stability of polyvinyl chloride, it is often necessary to add a thermal stabilizer to the product to inhibit thermal degradation. According to the above-mentioned thermal degradation mechanism of PVC, the corresponding thermal stabilization mechanism mainly includes the following types.

(1) the unstable chlorine atom (allyl chloride or tertiary chloride) in the polyvinyl chloride macromolecule is replaced or substituted to generate a relatively stable structure so as to inhibit dehydrochlorination.

(2) Absorbs and consumes HCl released in the processing process of the polyvinyl chloride, reduces or eliminates the autocatalysis effect of the HCl, and delays the thermal degradation of the PVC. Basic salts of inorganic acids and metal salts of weak organic acids are capable of absorbing HCl released by thermal degradation, such as calcium stearate, lead stearate, and the like.

(3) and the polyvinyl chloride is subjected to addition reaction with unsaturated bonds (such as C-C, C-O) in a polyvinyl chloride long chain, so that the conjugation effect is reduced.

(4) Passivating or neutralizing metal ions and other impurity ions that can catalyze accelerated thermal degradation of polyvinyl chloride.

Secondary stabilizers are substances which, when used alone, have no or a weak heat stabilizing effect on polyvinyl chloride, but are effective in improving other heat stabilizing systems. The common auxiliary stabilizers mainly comprise beta-diketone compounds, polyols, organic phosphites, epoxy compounds (such as linseed oil, epoxidized soybean oil, epoxidized oleic acid seeds and the like), and the like.

When the polyhydric alcohol is used alone, the thermal stabilization effect is not obvious, but the polyhydric alcohol plays a good auxiliary stabilization effect in a calcium/zinc stabilizer system. When the number of hydroxyl groups of the polyol is increased, the stabilizing effect thereof is increased. Because the hydroxyl of the polyalcohol and metal ions form ligand, the catalysis effect of chloride is reduced, and the stability of PVC is improved.

The thermoplastic polyurethane elastomer is a linear or slightly branched or crosslinked high molecular material prepared from polyisocyanate, polyester or polyether diol with hydroxyl and a low molecular weight diol chain extender through a step-by-step addition polymerization reaction. The TPU molecule contains both soft and hard segments, the soft segments determining some of the final properties of the TPU, such as elasticity, low temperature flexibility, and to some extent also the polymer swell properties and hydrolyzability. Similarly, the hard segment exhibits hardness, elastic modulus, mold release properties, and high temperature properties (thermal stability). The hard segment obtains a strong physical cross-linked structure through intermolecular hydrogen bonds to form a microphase-separated structure, so that rubber elasticity is exhibited even without a chemical cross-linked structure. The elastic modulus of the TPU is between that of plastic and rubber, the TPU can still keep better elasticity within a wider hardness range, and the TPU also has the processing property of plastic, and has good low-temperature resistance, oil resistance, solvent resistance and ozone resistance.

Microstructure research finds that hydrogen bonds of TPU are destroyed by adding PVC, and carbonyl groups in the TPU and alpha-H in the PVC form new hydrogen bonds, and a large amount of polar chlorine atoms in a polyvinyl chloride molecular chain can also form hydrogen bonds with hydrogen atoms in amino groups in the molecular structure of the TPU, so that the TPU and the PVC have strong bonding force, which shows that the blend has good compatibility and can be subjected to blending modification. The compatibility of the blend is mainly from the soft segment of polyurethane and the polyvinyl chloride chain segment. The compatibility of the blend is adversely affected by the increased hard segment content, and the lower the hard segment/soft segment ratio of the thermoplastic polyurethane, the better the compatibility of the thermoplastic polyurethane with the polyvinyl chloride blend. The reason is that the content of the hard segment of the TPU is increased, the ordered arrangement of the hard segment of the TPU is improved, a crystalline structure is formed, and the increase of the relative molecular mass of the soft segment is beneficial to the compatibility of the blend. The compatibility of the carbonyl in the TPU and the C-Cl in the PVC is improved through dipole-dipole interaction, so that the compatibility of the blend is improved.

In addition, both PVC and TPU are thermoplastic polar polymers, and the solubility parameter of PVC is 19.2-22.1 (J/cm)³)^1/2the solubility parameter of the TPU is 19.0-21.8 (J/cm)³)^1/2From the solubility parameter, the polyvinyl chloride and the thermoplastic polyurethane blend have good compatibility, and the materials with complementary performance can be obtained by blending the polyvinyl chloride and the thermoplastic polyurethane.

in one embodiment, the organic solvent in step (1) is one or more of N-methylpyrrolidone and cyclohexanone; preferably, the organic solvent in step (1) is cyclohexanone.

The alcoholysis method is the most important method in degrading waste polyurethane materials by the current chemical method, and the polyurethane is degraded into a mixture of polyether or polyester diol, polymer fragments with hydroxyl and low molecules, diamine and the like under the combined action of an alcoholysis agent and a catalyst; after alcoholysis is finished completely, the mixture is cooled and mixed with the neopolyol in proportion, and then the mixture can be directly polymerized with isocyanate to synthesize polyurethane again. In the method, a low molecular polyol compound is used as a decomposer, urethane groups or urea groups in polyurethane generally undergo transesterification with an alcoholysis agent under the condition of normal-pressure heating, and the generated degradation products are generally mixtures of low molecular polymer fragments with hydroxyl, polyether or polyester diol, diamine and the like.

The alcoholysis method has the remarkable characteristics that: the reaction can be carried out in a reaction instrument at normal pressure and medium temperature, and can be suitable for degradation of various polyurethane materials, and after the reaction is finished, excessive alcoholysis agents can be separated by methods such as reduced pressure distillation and the like. The selection of whether to separate and recycle the degradation product of the polyol or to directly reuse the degradation product can also be made according to the use purpose of the regenerated polyol and the degradation mode of the polyurethane.

After the alcoholysis reaction is finished, standing the degradation product for a period of time, and separating the final product into two layers; the lower product is an impurity, mainly comprising compounds containing urea groups and unbroken carbamate groups, and the like; and the upper product mainly comprises excessive alcoholysis agent (such as small molecular diol) and degradation target product, namely regenerated polyol with relatively high molecular mass.

The alcoholysis process of the polyurethane elastomer comprises the following steps:

Crushing or cutting the polyurethane elastomer into small particles, putting the small particles and an alcoholysis agent into a 500mL three-neck flask provided with a mechanical stirrer and a spherical condenser pipe according to a certain proportion, adding a certain amount of alcoholysis assistant agent, performing vacuum/nitrogen gas filling replacement for three times, placing the flask in an oil bath at a certain temperature, reacting for several hours, gradually dissolving the polyurethane elastomer in the alcoholysis agent solution along with the reaction, gradually deepening the color of the solution along with the prolonging of time, finally generating a brown transparent liquid, and filtering and washing after the reaction is finished to obtain a clear upper liquid.

in one embodiment, the average molecular weight of the polyester polyol or polyether polyol obtained after the polyurethane is degraded is 500-3500.

Gel permeation chromatography analysis

Taking 0.5ml of clear liquid obtained after alcoholysis of the polyurethane elastomer, adding DMF to 5ml, mixing uniformly and filtering; and (3) firstly, dropwise adding a drop of acetone into a test bottle for the gel permeation chromatograph, adding 2ml of mixed DMF solution, and uniformly mixing to be tested. Gel permeation chromatography was used to measure the average molecular weight of the alcoholysis product.

in one embodiment, the degradation agent is one or more of ethylene glycol, diethylene glycol, propylene glycol, 1, 3-propanediol, 1, 2-propanediol, dipropylene glycol, 1, 4-butanediol, 1, 5-pentanediol, 1, 6-hexanediol, polyoxyethylene glycol, polyoxypropylene glycol, polyethylene glycol, and dialkyl phosphate; preferably, the degradation agent is one or more of ethylene glycol, diethylene glycol, propylene glycol, 1, 3-propylene glycol, 1, 2-propylene glycol, dipropylene glycol, 1, 4-butanediol, 1, 5-pentanediol, 1, 6-hexanediol and dialkyl phosphate; preferably, the degradation agent is one or more of ethylene glycol and diethylene glycol.

in one embodiment, the degradation aid alkaline earth metal stearate is calcium stearate, zinc stearate, and/or magnesium stearate; preferably, the degradation aid alkaline earth metal stearate is calcium stearate.

When the polyhydric alcohol is used alone, the thermal stabilization effect is not obvious, but the polyhydric alcohol plays a good auxiliary stabilization effect in a calcium/zinc stabilizer system. When the number of hydroxyl groups of the polyol is increased, the stabilizing effect thereof is increased. Because the hydroxyl of the polyhydric alcohol can form a ligand with metal ions, the stability of the PVC is improved.

In one embodiment, the reaction temperature of the polyurethane elastomer in the step (1) is 100 to 170 ℃ when the polyurethane elastomer is decomposed; preferably, the reaction temperature during decomposition in the step (1) is 120-160 ℃.

The alcoholysis reaction is a process requiring a large amount of endotherms, and it was previously considered that the reaction temperature is generally in the range of 150 ℃ to 250 ℃. In the reaction process, the molecular movement speed of the alcoholysis agent is increased along with the increase of the temperature, so that the contact probability of PU and the alcoholysis agent is increased, and the reaction is favorable for going forward and backward. It is generally considered that slow alcoholysis begins at 150 ℃, but the specific temperature should be corrected again according to the characteristics of the alcoholysis agent, if the reaction temperature is too high, not only the volatilization loss of the alcoholysis agent is increased, especially if the temperature is higher than 200 ℃, the dihydric alcohol in the degradation system is easy to generate side reactions such as etherification, oxidation and the like, and the chance of main reaction is reduced, but also the decarboxylation reaction is easy to occur on the regenerated polyhydric alcohol of the alcoholysis product, so that the reaction center is lost, besides, the color of the reaction system is also increased, so that 200 ℃ is generally the upper limit of the reaction temperature for the alcoholysis of polyurethane.

With the increase of the reaction temperature, the viscosity of the alcoholysis product is gradually reduced, the hydroxyl value is gradually increased, when the reaction temperature reaches 160 ℃ or above, the viscosity and the hydroxyl value are slightly changed, so that the polyurethane elastomer is decomposed into polyol mainly at 160 ℃ in the presence of an alcoholysis agent, and therefore, 160 ℃ is selected as the alcoholysis temperature of the polyurethane elastomer.

in one embodiment, the reaction time for decomposing the polyurethane elastomer in the step (1) is 1-10 h; preferably, the reaction time for decomposing the polyurethane elastomer in the step (1) is 3-8 h.

Determination of the end-point of the reaction

the end point of alcoholysis reaction can be controlled effectively to control the time of full reaction, which has great influence on the performance of polyol regeneration by main product degradation. If the alcoholysis reaction time is too short, the alcoholysis reaction of the polyurethane is not necessarily complete, so that unreacted PU remains in the product or oligomers with relatively high molecular weight exist in the product, the difficulty of purifying the polyol from the degradation product in the later period is increased by the remaining undegraded PU, and the oligomers with relatively high molecular weight can also affect the viscosity of the regenerated polyol, so that the viscosity of the regenerated polyol is obviously increased, the quality of the regenerated polyol is reduced, and the application range is reduced; if the alcoholysis reaction time is too long, energy and time are wasted firstly, meanwhile, along with the increase of the reaction time, the volatilization amount of the alcoholysis agent is increased, the possibility of side reactions such as oxidation, etherification and the like of the alcoholysis agent is increased by long-time heating, the color of a reaction system is deepened, and if the polyurethane foam is prepared again by using the recycled polyol with darker color, the color of a finished product is correspondingly darker.

The method determines the end point of the alcoholysis reaction by measuring the dissolution degree of the alcoholysis product in the organic solution at different time points, and is practical, simple and time-saving. The method comprises the following specific operations: taking a certain amount of samples at intervals of half an hour or (15min, time interval is changed to be more accurate) at the later stage of alcoholysis reaction (after 120 min), firstly cooling the samples to room temperature, then putting the taken samples into methanol for dissolving, filtering undissolved substances (unreacted PU), drying and weighing, and calculating the degradation rate; by the time the sample methanol solution is clear and transparent and contains no suspended material, it is considered that the end point of the alcoholysis reaction has been reached.

When the alcoholysis reaction lasts for 5h, the alcoholysis is substantially complete, the viscosity and hydroxyl number of the alcoholysis product change very little, and the molecular weight of the product obtained by gel permeation chromatography is substantially minimal when the reaction lasts for 5 h. From the aspect of production efficiency, the reaction time should be selected to be 5 hours.

In one embodiment, the weight ratio of the sample of polyurethane-containing polyvinyl chloride resin to the degrading agent is 1: (0.04 to 0.4); preferably, the weight ratio of the sample of the polyvinyl chloride resin containing polyurethane to the degradation agent is 1 (0.5-0.9).

In one embodiment, the alcoholysis product has a hydroxyl number of from 15 to 40 mgKOH/g.

In one embodiment, the alcoholysis product has a viscosity of 500 to 2500mPa · S (25 ℃); preferably, the alcoholysis product has a viscosity of 500 to 2300mPa · S (25 ℃).

Viscosity analysis

a drop of alcoholysis-treated clear solution is taken to test the viscosity of the alcoholysis product at 25 ℃ on a viscometer, and the degree of alcoholysis is examined by comparing the viscosities, wherein the higher the viscosity is, the higher the molecular weight is, and the more incomplete the alcoholysis is. Analysis of hydroxyl number

The invention adopts an acetic anhydride-pyridine method to determine the hydroxyl value of an alcoholysis product, and comprises the following specific steps:

1) Preparation of acetic anhydride-pyridine solution

Mixing 10.00ml of acetic anhydride with 30ml of pyridine, and storing in a conical flask;

2) Preparation and calibration of 1.000mol/L NaOH solution

40g of sodium oxysulfide is weighed, dissolved in the steaming feed water and is added into a volumetric flask with 1000ml of volume. Accurately weighing about 4g of potassium hydrogen phthalate in a triangular flask by using an analytical balance, heating and dissolving by using distilled water, adding four drops of phenolphthalein, titrating by using a prepared NaOH solution until pink is taken as an end point, measuring in parallel twice, and taking an average value;

3) Determination of hydroxyl number

uniformly stirring alcoholysis products, accurately weighing 1-2g of a sample in a 10ml conical flask, adding 5.00ml of acetic anhydride-pyridine solution, carrying out boiling water bath for 30min, cooling to room temperature, adding 20ml of distilled water, using phenolphthalein as an indicator under severe oscillation, titrating with a sodium oxysulfate standard solution until pink just appears, keeping Imin fadeless as a terminal point, recording the amount of NaOH solution, carrying out parallel twice, taking an average value, and simultaneously carrying out a blank test;

Hydroxyl value (OHv) ═ 56.1X (V)₀-V₂)C)/m

Wherein OHV is defined as acid-base neutralization, and each gram of product is completely neutralized to consume the milligrams of potassium hydroxide, and the unit is mgKOH/g;

V₀One drop of the volume of NaOH solution used for the blank (mL);

V₂-the volume of NaOH solution (mL) used to titrate the sample;

C-concentration of NaOH solution (mol/L);

m-sample mass (g).

The invention uses 1, 4-butanediol as a degradation agent and triethanolamine as a degradation assistant agent to successfully degrade the polyurethane elastomer, so as to obtain the recyclable polyol and toluene diisocyanate, and the recyclable polyol and the toluene diisocyanate are subjected to polymerization reaction to generate new polyurethane.

Synthesis of polyurethane

(1) Synthesis of prepolymer

in a four-neck flask provided with a thermometer, a constant pressure dropping funnel, a stirrer and a nitrogen protection device, 0.01mol of toluene diisocyanate is dissolved in DMAC (dimethylacetamide) and put into a 100ml four-neck flask under the nitrogen atmosphere; heating the system to 60 ℃, repeatedly adding 0.01mol of polyurethane degradation product polyol, and stirring for reaction for 2 hours;

(2) chain extension and crosslinking reaction

Adding 1, 4-butanediol (the mass ratio of 1, 4-butanediol to the prepolymer is 3%) into the prepolymer, heating to 75 ℃ and reacting for 2.5 hours;

(3) Capping reactions

And after chain extension is finished, adding 20ml of methanol for end capping to obtain a crude polyurethane product.

The invention decomposes polyurethane in polyvinyl chloride into polyol and compounds containing carbamido and unbroken carbamate groups through a degradation agent and a degradation assistant, then separates the polyvinyl chloride from polyurethane degradation products through solubility difference, and then adds toluene diisocyanate and the polyol to carry out polymerization reaction to obtain new polyurethane, thereby separating the polyurethane in the polyvinyl chloride.

in addition, the degradation agent dihydric alcohol and the degradation assistant agent calcium stearate can not only promote the degradation of the polyurethane but also promote the thermal stability of the polyvinyl chloride.

The present invention will be specifically described below by way of examples. It should be noted that the following examples are only for illustrating the present invention and should not be construed as limiting the scope of the present invention, and that the insubstantial modifications and adaptations of the present invention by those skilled in the art based on the above disclosure are still within the scope of the present invention.

In addition, the raw materials used are commercially available from national chemical reagents, unless otherwise specified.

Example 1

The sample was a polyvinyl chloride resin containing 10% polyurethane. Weighing 10.0g of sample, dissolving in 200ml of cyclohexanone which is an organic solvent, adding 0.1g of ethylene glycol which is a degradation agent and 0.015g of calcium stearate which is an auxiliary degradation agent, carrying out vacuum/nitrogen filling replacement for 3 times, placing a flask in an oil bath (160 ℃) with a certain temperature, reacting for 5 hours, gradually deepening the color of the solution along with the prolonging of the time along with the reaction, finally generating a brown transparent liquid, filtering and washing after the reaction is finished to obtain a clear upper layer liquid (polyalcohol), concentrating and drying the lower layer solution, adding 200ml of ethanol, stirring for 0.5 hour, filtering, separating soluble components and insoluble components (polyvinyl chloride) in the solution, concentrating and drying the upper layer solution, adding 50ml of DMAC and 0.01mol of toluene diisocyanate, heating to 60 ℃, stirring and reacting for 2 hours, adding 1, 4-butanediol (the mass ratio of 1, 4-butanediol to the prepolymer is 3 percent), and finally adding, heating to 75 ℃ for reaction for 2.5h, and finally adding 20ml of methanol for end capping to obtain polyurethane; concentrating and drying the decomposition liquid, sampling and carrying out GC-MS detection, wherein the detection conditions of GC-MS are as follows: temperature rising procedure: maintaining at 70 deg.C for 1min, raising temperature to 280 deg.C at 20 deg.C/min, and maintaining for 8.5 min; CD-5 MS column: 30 m.times.0.25 mm.times.0.25 μm; the carrier gas is helium (with the purity of 99.999 percent) and the flow rate is 1.0 mL/min; injecting sample without shunting, wherein the temperature of a sample injection port is 250 ℃, and the sample injection amount is 1 mu L; electron impact ion source (EI source) with electron impact energy of 70 eV; the transmission line temperature is 280 ℃; the ion source temperature is 250 ℃; the solvent delay time is 3.5 min; a full SCAN and selective ion mode (SCAN/SIM) SCAN range of 40-400 amu; and (3) carrying out infrared detection on the insoluble component of the lower layer and the synthesized polyurethane, and combining detection data to detect that the content of tetrahydrofuran polyether glycol in the sample is 0.65 percent and the weight of polyvinyl chloride is 7.19 g.

Example 2

The sample was a polyvinyl chloride resin containing 10% polyurethane. Weighing 10.0g of sample, dissolving in 200ml of organic solvent cyclohexanone, adding 0.1g of degradation agent diethylene glycol and 0.015g of degradation aid calcium stearate, carrying out vacuum/nitrogen gas filling replacement for 3 times, placing a flask in an oil bath (160 ℃) at a certain temperature, reacting for 5 hours, gradually deepening the color of the solution along with the time extension along with the reaction, finally generating brown transparent liquid, filtering and washing after the reaction is finished to obtain clear upper layer liquid (polyalcohol), concentrating and drying the lower layer solution, adding 200ml of ethanol, stirring for 0.5 hour, filtering, separating soluble components and insoluble components (polyvinyl chloride) in the solution, concentrating and drying the upper layer solution, adding 50ml of DMAC and 0.01mol of toluene diisocyanate, heating to 60 ℃, stirring and reacting for 2 hours, adding 1, 4-butanediol (the mass ratio of 1, 4-butanediol to the prepolymer is 3 percent), and finally adding, heating to 75 ℃ for reaction for 2.5h, and finally adding 20ml of methanol for end capping to obtain polyurethane; concentrating the upper layer solution, drying, sampling, and performing GC-MS detection under the following detection conditions: temperature rising procedure: maintaining at 70 deg.C for 1min, raising temperature to 280 deg.C at 20 deg.C/min, and maintaining for 8.5 min; CD-5 MS column: 30 m.times.0.25 mm.times.0.25 μm; the carrier gas is helium (with the purity of 99.999 percent) and the flow rate is 1.0 mL/min; injecting sample without shunting, wherein the temperature of a sample injection port is 250 ℃, and the sample injection amount is 1 mu L; electron impact ion source (EI source) with electron impact energy of 70 eV; the transmission line temperature is 280 ℃; the ion source temperature is 250 ℃; the solvent delay time is 3.5 min; a full SCAN and selective ion mode (SCAN/SIM) SCAN range of 40-400 amu; and (3) carrying out infrared detection on the insoluble component at the lower layer and the synthesized polyurethane, and measuring that the content of tetrahydrofuran polyether glycol in the sample is 0.7% and the weight of polyvinyl chloride is 7.25g by combining detection data.

Example 3

The same as in example 2, except that the degradation assistant was magnesium stearate, the tetrahydrofuran homopolyether diol content in the sample was 0.6% and the polyvinyl chloride weight was 7.08 g.

Example 4

The same as in example 2, except that the amount of the degradation agent was 0.04g and the amount of the co-degradation agent was 0.008g, the amount of the tetrahydrofuran homopolyether diol measured in the sample was 0.2% and the weight of the polyvinyl chloride was 8.6g (containing polyurethane, which was completely degraded).

Example 5

The same as in example 2, except that the amount of the degradation agent was 0.4g and the amount of the co-degradation agent was 0.04g, the tetrahydrofuran homopolyether diol content in the sample was 0.66%, and the polyvinyl chloride weight was 7.17 g.

Example 6

The same as in example 2, except that the amount of the degradation agent was 0.4g and the amount of the co-degradation agent was 0.4g, the tetrahydrofuran homopolyether diol content in the sample was 0.69% and the polyvinyl chloride weight was 7.26 g.

example 7

The same as in example 2, except that the degradation reaction time was 1 hour, the tetrahydrofuran homopolyether diol content in the sample was 0.1% and the polyvinyl chloride weight was 7.1 g.

Example 8

The same as in example 2, except that the degradation reaction time was 10 hours, the tetrahydrofuran homopolyether diol content of the sample was 0.62% and the polyvinyl chloride weight was 7.3 g.

Example 9

The sample was a polyvinyl chloride resin containing 15% polyurethane. Weighing 10.0g of sample, dissolving in 200ml of organic solvent cyclohexanone, adding 0.1g of degradation agent diethylene glycol and 0.015g of degradation aid calcium stearate, carrying out vacuum/nitrogen gas filling replacement for 3 times, placing a flask in an oil bath (160 ℃) at a certain temperature, reacting for 5 hours, gradually deepening the color of the solution along with the time extension along with the reaction, finally generating brown transparent liquid, filtering and washing after the reaction is finished to obtain clear upper layer liquid (polyalcohol), concentrating and drying the lower layer solution, adding 200ml of ethanol, stirring for 0.5 hour, filtering, separating soluble components and insoluble components (polyvinyl chloride) in the solution, concentrating and drying the upper layer solution, adding 50ml of DMAC and 0.01mol of toluene diisocyanate, heating to 60 ℃, stirring and reacting for 2 hours, adding 1, 4-butanediol (the mass ratio of 1, 4-butanediol to the prepolymer is 3 percent), and finally adding, heating to 75 ℃ for reaction for 2.5h, and finally adding 20ml of methanol for end capping to obtain polyurethane; concentrating and drying the decomposition liquid, sampling and carrying out GC-MS detection, wherein the detection conditions of GC-MS are as follows: temperature rising procedure: maintaining at 70 deg.C for 1min, raising temperature to 280 deg.C at 20 deg.C/min, and maintaining for 8.5 min; CD-5 MS column: 30 m.times.0.25 mm.times.0.25 μm; the carrier gas is helium (with the purity of 99.999 percent) and the flow rate is 1.0 mL/min; injecting sample without shunting, wherein the temperature of a sample injection port is 250 ℃, and the sample injection amount is 1 mu L; electron impact ion source (EI source) with electron impact energy of 70 eV; the transmission line temperature is 280 ℃; the ion source temperature is 250 ℃; the solvent delay time is 3.5 min; a full SCAN and selective ion mode (SCAN/SIM) SCAN range of 40-400 amu; and (3) carrying out infrared detection on the insoluble component at the lower layer and the synthesized polyurethane, and measuring the content of the tetrahydrofuran polyether glycol in the sample to be 1.06 percent and the weight of the polyvinyl chloride to be 7.0g by combining detection data.

Example 10

The same as in example 9, except that the degradation reaction time was 10 hours, the tetrahydrofuran homopolyether diol content of the sample was 0.99%, and the polyvinyl chloride weight was 6.8 g.

example 11

the same as in example 2, except that the degradation reaction temperature was 170 ℃ was changed, it was found that the tetrahydrofuran homopolyether diol content of the sample was 0.68% and the polyvinyl chloride weight was 4.0 g.

Example 12

the same as in example 9, except that the degradation reaction temperature was 170 ℃ was changed, the tetrahydrofuran homopolyether diol content in the sample was 1.08%, and the polyvinyl chloride weight was 3.1 g.

comparative example 1

The same as example 2, except that the degradation reaction temperature was 100 ℃ and the weight of polyvinyl chloride was 9.2g (relatively small degradation of polyurethane) in the sample, the content of tetrahydrofuran homopolyether diol was 0.13%.

Comparative example 2

The same as in example 2, except that the degradation reaction temperature was 200 ℃ and the content of tetrahydrofuran homopolyether diol in the sample was 0.69% by weight, the weight of polyvinyl chloride was 2.2 g.

comparative example 3

The same as example 2, except that the degradation agent was triethanolamine, the tetrahydrofuran homopolyether diol content in the sample was 0.58% and the polyvinyl chloride weight was 5.2 g.

Comparative example 4

The same as example 2, except that calcium stearate, a degradation assistant, was not contained, the tetrahydrofuran homopolyether diol content in the sample was 0.36%, and the weight of polyvinyl chloride was 6.2g (polyvinyl chloride was partially decomposed, and polyurethane was completely degraded).

In conclusion, the invention degrades TPU by a chemical method and then separates TPU from PVC, and polyurethane is degraded and then polymerized on the premise of ensuring that polyvinyl chloride is not decomposed, so that polyurethane and polyvinyl chloride are separated and analyzed.

The above examples are merely illustrative and serve to explain some of the features of the invention. The appended claims are intended to claim as broad a scope as is contemplated, and the examples presented herein are merely illustrative of selected implementations in accordance with all possible combinations of examples. Accordingly, it is applicants' intention that the appended claims not be limited by the choice of examples illustrating features of the invention, and that technological advances will form possible equivalents or sub-substitutes not presently contemplated for reasons of inaccuracy of the linguistic expressions, and that such variations are to be construed as being covered by the appended claims where possible.

Claims

1. A method for analyzing polyurethane in a polyvinyl chloride system is characterized by comprising the following steps:

(5) And (3) detection: drying the insoluble components in the step (3) and the polyurethane in the step (4) and then carrying out infrared detection; performing GC-MS detection on the decomposition product containing the polyol and the oligomer in the step (2);

The reaction temperature in the decomposition in the step (2) is 160 ℃;

the degradation agent is one or more of ethylene glycol, diethylene glycol, propylene glycol, 1, 3-propylene glycol, 1, 2-propylene glycol, dipropylene glycol, 1, 4-butanediol, 1, 5-pentanediol, 1, 6-hexanediol, polyoxyethylene glycol, polyoxypropylene glycol and polyethylene glycol;

the degradation assistant is alkaline earth metal stearate;

The degradation assistant alkaline earth metal stearate is calcium stearate and/or magnesium stearate;

The weight ratio of the polyvinyl chloride resin sample containing polyurethane to the degrading agent is 1: (0.04 to 0.4);

The weight ratio of the degradation agent to the degradation assistant agent is 1: (0.1 to 0.3);

The decomposition reaction time in the step (2) is 5 h;

The hydroxyl value of the decomposed product is 15-40 mgKOH/g;

The viscosity of the decomposed product is 500-2500 mPa & s;

the detection conditions of the GC-MS are as follows: temperature rising procedure: maintaining at 70 deg.C for 1min, raising temperature to 280 deg.C at 20 deg.C/min, and maintaining for 8.5 min; CD-5 MS column: 30 m.times.0.25 mm.times.0.25 μm; the carrier gas is helium, and the flow rate is 1.0 mL/min; injecting sample without shunting, wherein the temperature of a sample injection port is 250 ℃, and the sample injection amount is 1 mu L; electron bombardment ion source, electron bombardment energy 70 eV; the transmission line temperature is 280 ℃; the ion source temperature is 250 ℃; the solvent delay time is 3.5 min; full scan and selective ion mode, with a scan range of 40-400 amu.

2. the method for analyzing polyurethane in a polyvinyl chloride system according to claim 1, wherein the organic solvent in step (1) is one or more of N-methylpyrrolidone and cyclohexanone.

3. The method for analyzing polyurethane in a polyvinyl chloride system according to claim 1, wherein the weight ratio of the degradation agent to the degradation assistant agent is 1: (0.1-0.2).