CN112592457A

CN112592457A - Polyisocyanate composition and preparation method and application thereof

Info

Publication number: CN112592457A
Application number: CN202011386450.0A
Authority: CN
Inventors: 俞勇; 崔学磊; 郭耀允; 尚永华; 韩金平; 李文滨; 刘德刚; 黎源
Original assignee: Wanhua Chemical Group Co Ltd; Wanhua Chemical Ningbo Co Ltd
Current assignee: Wanhua Chemical Group Co Ltd; Wanhua Chemical Ningbo Co Ltd
Priority date: 2020-12-01
Filing date: 2020-12-01
Publication date: 2021-04-02
Anticipated expiration: 2040-12-01
Also published as: CN112592457B

Abstract

The invention relates to a polyisocyanate composition and a preparation method and application thereof, wherein the numerical value of subtracting the mass content of hydrolytic chlorine from the mass content of alkaline hydrolytic chlorine in the polyisocyanate composition is 0.1ppm-100 ppm; the mass content of the alkaline hydrolysis chlorine is calculated by the relative atomic mass of chlorine atoms of halogen dissociated under alkaline conditions and/or halogen dissociated under the temperature condition of more than 100 ℃. The invention provides a polyisocyanate composition containing a specific amount of alkaline chlorine hydride, which can dissociate chlorine hydride in the alkaline chlorine hydride to poison a catalyst when local violent heat release is caused when local runaway occurs in the reaction, so as to reduce the reaction activity of a local excessive reaction area, thereby avoiding the turbidity of polyurethane synthetic emulsion and further improving the light transmittance and yellowing resistance of a polyurethane product.

Description

Polyisocyanate composition and preparation method and application thereof

Technical Field

The invention relates to the technical field of polyurethane, in particular to a polyisocyanate composition and a preparation method and application thereof.

Background

Polyurethane is one of synthetic resins having excellent comprehensive properties. Because of the variety of synthetic monomers, mild, specific and controllable reaction conditions, large formula adjustment margin and the microstructure characteristics of high polymer materials, the material can be widely used for coatings, adhesives, foamed plastics, synthetic fibers and elastomers, and becomes one of the essential materials for clothes, food, lives and rows of people; moreover, the polyurethane resin has already formed a multi-variety and multi-series material family, and forms a complete polyurethane industrial system, which is not possessed by other resins.

In the large-scale polyurethane production process, due to the defects of equipment or poor mixing effect, the reaction concentration in a local area in a reaction space is too high, so that the reaction is excessively violent, a large amount of heat is released to promote the excessive reaction, so that the local reaction is out of control, the turbidity of the polyurethane synthetic emulsion is easily caused, and finally the unqualified polyurethane product is caused.

In the current industry standard, the influence of the hydrolyzed chlorine impurities in the polyisocyanate on the downstream polyurethane industry is clear, for example, the national standard GB/T37042 and 2018 of hexamethylene diisocyanate clearly proposes to control the hydrolyzed chlorine within 100ppm, for example, the patent CN103319372A proposes to control the alcohol impurities in the raw materials, and the patent CN109761855A proposes to control the content of the secondary amine in the raw material amine, and the purpose is to reduce the content of the hydrolyzed chlorine in the product.

CN110511163A discloses a method for preparing polyisocyanate by photochemical reaction and a method for preparing aqueous polyurethane resin, and specifically discloses that the chlorine content in polyisocyanate can affect the yellowing resistance of aqueous polyurethane resin, and even can directly cause yellowing of aqueous polyurethane resin, and at the same time can have adverse effect on the reactivity of part of the system.

CN1064074A discloses a process for reducing the hydrolysable chloride content of toluene diisocyanate, especially its distillation residue, which specifically discloses that the hydrolysable chloride content of the diisocyanate is too high and that it is viscosity unstable and inactive and therefore needs to be handled to reduce its hydrolysable chloride content to a level where the residue is activity and viscosity stable.

Therefore, there is a need in the art to develop solutions for further improving the quality of polyurethane products.

Disclosure of Invention

One of the objectives of the present invention is to provide a polyisocyanate composition, which can solve the problem of unstable reactivity in the prepolymerization stage and the chain extension stage, which is easily generated in the polyurethane resin synthesis process, and effectively improve the turbidity of the synthesized emulsion, thereby improving the light transmittance and yellowing resistance of the polyurethane product.

In order to achieve the purpose, the invention adopts the following technical scheme:

the present invention provides a polyisocyanate composition having a value of 0.1ppm to 100ppm, for example, 0.2ppm, 0.3ppm, 0.4ppm, 0.5ppm, 1ppm, 2ppm, 3ppm, 4ppm, 5ppm, 6ppm, 7ppm, 8ppm, 9ppm, 10ppm, 15ppm, 20ppm, 25ppm, 30ppm, 35ppm, 40ppm, 45ppm, 50ppm, 55ppm, 60ppm, 65ppm, 70ppm, 75ppm, 80ppm, 85ppm, 90ppm, 95ppm, 98ppm, etc. obtained by subtracting the mass content of hydrolyzed chlorine from the mass content of alkali hydrolyzed chlorine;

the mass content of the alkaline hydrolysis chlorine is calculated by the relative atomic mass of chlorine atoms of halogen dissociated under alkaline conditions and/or halogen dissociated under the temperature condition of more than 100 ℃.

The polyisocyanate composition of the present invention includes impurities in addition to the polyisocyanate, and is therefore referred to as a composition, where polyisocyanate refers to an isocyanate having at least two (e.g., 2, 3, 4, etc.) isocyanate groups (O ═ C ═ N —). In the present invention, the concept of hydrolyzing chlorine is common knowledge in the art.

The calculation in terms of the relative atomic mass of chlorine atoms in the present invention means: the amount or molar content of the substance from which the dissociated halogen is obtained is measured, and the mass or mass content is obtained in terms of the relative atomic mass of chlorine atoms (35.45g/mol) regardless of the specific halogen. Illustratively, when the dissociated halogen is bromine and the amount of the substance is 1mol, the mass of the alkaline chloride is 1mol × 35.45g/mol — 35.45g, and the mass of the alkaline chloride divided by the total mass of the polyisocyanate composition is the mass content of the alkaline chloride.

Because the formulations are different in the downstream polyurethane preparation process, the acid-base environment and the reaction temperature condition in the polyurethane synthesis process are different, and the alkali-hydrolyzable chlorine impurities in the polyisocyanate composition can be dissociated into chlorine in the polyurethane synthesis process.

The research of the inventor finds that the polyisocyanate composition containing the specific amount of the alkaline chlorine hydride dissociates the chlorine hydride in the alkaline chlorine hydride when the local violent heat release is caused when the local runaway of the reaction occurs, and poisons the catalyst, so as to reduce the reaction activity of a local excessive reaction area, avoid the turbidity of the polyurethane synthetic emulsion, and further improve the light transmittance and the yellowing resistance of the polyurethane product.

However, when the amount of alkaline hydrolysis chlorine is higher than a certain amount, the chlorine dissociated under alkaline conditions may further diffuse outward after inhibiting local excessive reaction, and poison a catalyst in a normal reaction region, resulting in instability of reaction activity, and further causing problems in thermal control during synthesis, resulting in turbidity of an emulsion for polyurethane synthesis, adverse effects on a polyurethane product, reduction in light transmittance, and deterioration of yellowing resistance.

Preferably, the amount of alkaline hydrolysis chlorine minus the amount of hydrolysis chlorine in the polyisocyanate composition is from 0.2ppm to 60ppm, preferably from 0.4ppm to 40 ppm.

In the preferred technical scheme of the invention, the numerical value obtained by subtracting the mass content of the hydrolyzed chlorine from the mass content of the alkaline hydrolyzed chlorine is further preferred, so that the turbidity problem of the polyurethane synthetic emulsion can be further improved, and the light transmittance and yellowing resistance of the product can be improved. The turbidity problem of the polyurethane synthetic emulsion is aggravated due to the excessively low alkali-hydrolyzable chlorine amount, the light transmittance of the polyurethane product is reduced, and the yellowing resistance of the polyurethane product is poor due to the excessively high alkali-hydrolyzable chlorine amount, so that the turbidity problem of the synthetic emulsion is aggravated and the light transmittance of the polyurethane product is reduced.

Preferably, the halogen comprises any one or a combination of at least two of fluorine, chlorine, bromine or iodine.

Preferably, the polyisocyanate composition includes a combination of polyisocyanate, alkali-hydrolyzable chlorine-type impurities and hydrolyzable chlorine-type impurities. The alkaline chlorine-hydrolyzing impurities are substances obtained by dissociation, and the hydrolytic chlorine impurities are substances obtained by dissociation.

According to the research of the inventor of the invention, one of the sources of the alkaline chlorine-decomposing impurities is found as follows: in the phosgenation reaction process, one isocyanic acid radical in the main product polyisocyanate is dropped to form an olefin structure, and then the olefin structure is further combined with hydrogen chloride under the phosgenation environment.

In the invention, the alkaline chlorine in the polyisocyanate is chlorine which is difficult to remove by a conventional separation means or chlorine which needs great energy consumption and material consumption to remove, and needs to be controlled from the source.

Preferably, the polyisocyanate is a diisocyanate.

Preferably, the polyisocyanate comprises any one or a combination of at least two of alicyclic diisocyanate, aromatic diisocyanate or chain diisocyanate.

Preferably, the polyisocyanate includes any one or a combination of at least two of dicyclohexylmethane diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, m-xylylene isocyanate, p-xylylene isocyanate, 1, 3-dimethylisocyanate cyclohexane, 1, 4-dimethylisocyanate cyclohexane, tetramethylene diisocyanate, pentamethylene diisocyanate, Toluene Diisocyanate (TDI), diphenylmethane diisocyanate (MDI), benzene diisocyanate, naphthalene diisocyanate, and cyclohexyl diisocyanate.

Preferably, the polyisocyanate comprises dicyclohexylmethane diisocyanate, and the alkaline-hydrolyzable chlorine impurity comprises any one or at least two of the following compounds:

and X is F, Cl, Br or I.

Preferably, the polyisocyanate comprises isophorone diisocyanate, and the alkaline-hydrolyzable chlorine impurities comprise any one or at least two of the following compounds in combination:

and X is F, Cl, Br or I.

Preferably, the polyisocyanate comprises hexamethylene diisocyanate, and the alkali-hydrolyzable chlorine-type impurity comprises any one or at least two of the following compounds in combination:

and X is F, Cl, Br or I.

Preferably, the polyisocyanate composition further comprises an anti-aging auxiliary agent. The aging auxiliary agent is added to enhance the storage stability of the polyisocyanate composition, prolong the shelf life of the polyisocyanate composition, and facilitate the realization of stable color number and difficult yellowing of the polyisocyanate composition in the process of preparing polyurethane resin by using the polyisocyanate composition.

Preferably, the anti-aging aid comprises any one or at least two combinations of hindered phenol antioxidants, sulfonamide group-containing compounds, or organophosphites, preferably hindered phenol antioxidants, and more preferably any one or at least two combinations of antioxidant 264 (e.g., Eastman chemical, Tenox BHT, usa), antioxidant 245 (e.g., BASF, Irganox 245, germany), or antioxidant 1076 (e.g., BASF, Irganox1076, germany).

Preferably, the amount by mass of the anti-aging auxiliary in the polyisocyanate composition is 50 to 5000ppm, such as 100ppm, 500ppm, 1000ppm, 1500ppm, 2000ppm, 2500ppm, 3000ppm, 3500ppm, 4000ppm, 4500ppm, etc., preferably 100-1000 ppm.

Preferably, the raw materials for the preparation of the polyisocyanate composition comprise a combination of polyamines and phosgene-based raw materials. In the present invention, the polyamine means a compound having at least two (e.g., 2, 3, 4, etc.) amino groups.

Preferably, the total content by mass of impurities having an unsaturated olefin-based structure, a secondary amine-based structure or a hydroxyl-based structure in the polyamine is 0.1ppm to 400ppm, for example, 0.5ppm, 1ppm, 5ppm, 10ppm, 50ppm, 100ppm, 150ppm, 200ppm, 250ppm, 300ppm, 350ppm and the like.

According to the studies of the inventors of the present invention, another source of alkaline hydrolysis chlorine is: in the preparation process of raw material polyamine, some components of which generate alkaline chlorine during the subsequent phosgenation to prepare isocyanate, the specific structure includes but is not limited to the following cases: a) unsaturated olefin structure b) secondary amine structure c) hydroxyl structure, substances containing the above structures are generally difficult to separate from the starting polyamine and react with phosgene or hydrogen chloride during phosgenation, particularly during gas phase phosgenation, to form alkaline chlorides. Therefore, in the case of the raw material polyamine, the total amount of these species needs to be controlled, and in the present invention, it is recommended to control the total amount to 0.1ppm to 400 ppm.

In the present invention, the determination of the mass content of the hydrolysis chlorine is the prior art, including but not limited to the method provided in GB/T37042-2018, and regarding the mass content of the alkaline hydrolysis chlorine, the skilled person can also test by conventional means, and the present invention provides only the following test methods by way of example, but not limited to:

the test principle of the method is as follows: the alkali-hydrolyzable chlorine in the polyisocyanate is mainly chlorine which can be dissociated under the alkaline condition, firstly, isocyanate in the polyisocyanate is reacted through the reaction of ethanol and the polyisocyanate, then, halogen which can be subjected to alkali-hydrolyzable is dissociated under the alkaline condition, the dissociated halogen ion forms corresponding salt, and then, the content of the salt is measured by a silver nitrate standard solution by using a potentiometric titration method.

The instruments used for the test procedure were:

(a) a potentiometric titrator;

(b) a composite silver electrode;

(c) an electromagnetic stirrer;

(d) and (3) constant-temperature water bath: 80 ℃;

(e) general experimental apparatus.

The reagents used in the test procedure were:

(a) water: water treated with ion exchange resin;

(b) acetone (AR);

(c) nitric acid solution: nitric acid (GB626) and water were mixed at 1:3 volume;

(d) sodium chloride standard solution: 1mL is equivalent to 1mg and is prepared by the method specified in GB 601;

(e) silver nitrate standard solution: c (AgNO)₃) Preparing and calibrating by a method specified in GB601 when the concentration is 0.05 mol/L;

(f) ethanol (AR);

(g) sodium hydroxide standard solution (2 mol/L): 80g of sodium hydroxide (GB629) was weighed out and dissolved in water and diluted to 1000 mL.

By way of example only, the specific test steps are as follows:

(a) putting 10g-15g (accurate to 0.1mg) of sample into a 300mL beaker, loading into a rotor, adding 30mL of acetone, adding 50mL of ethanol solution after the sample is completely dissolved, and putting into a constant-temperature water bath at 60 ℃ for full reaction;

(b) after reacting for 30min, adding 100mL of NaOH solution, and continuing to react for 50min on a constant-temperature water bath at 60 ℃;

(c) taking down the beaker, and cooling the beaker in an ice-water bath to below 10 ℃;

(d) accurately adding 2mL of sodium chloride standard solution into a beaker, and adding 20mL of 1:3 nitric acid solution; carrying out potentiometric titration, and recording the volume of the consumed silver nitrate standard solution by taking the inflection point of the obtained curve as an end point;

(e) and simultaneously performing a blank test.

The alkaline hydrolysis chlorine is calculated according to the following formula:

in the formula: percent Cl-hydrolyzed chloride (as chlorine), ppm;

v-volume of silver nitrate standard solution consumed in titrating the sample, mL;

V₀-volume of silver nitrate standard solution consumed in titration of blank, mL;

c-actual concentration of silver nitrate standard solution, mol/L;

m-mass of sample, g;

0.03546-and 1.00mL silver nitrate standard solution [ C (AgNO)₃)＝1.000mol/L]The equivalent is the mass of chlorine atoms expressed in grams, expressed in g/mol.

The second object of the present invention is to provide a process for producing the polyisocyanate composition according to the first object, which comprises: polyamine and phosgene raw materials are subjected to phosgenation reaction to obtain the polyisocyanate composition.

Preferably, the polyamine comprises m-xylylenediamine, p-xylylenediamineXylylenediamine, 1, 3-cyclohexyldimethylamine, 1, 4-butanediamine, 1, 6-hexanediamine, 1, 4-diaminocyclohexane, diaminodicyclohexylmethane (for example, industrial H)₁₂MDA which is a mixture comprising 4, 4-diaminodicyclohexylmethane, 2, 2-diaminodicyclohexylmethane, etc.), toluenediamine, methylenedianiline (e.g., 2,2 '-methylenedianiline, 4' -methylenedianiline), isophoronediamine, phenylenediamine, naphthalenediamine, 1, 8-octanediamine, 1, 10-decanediamine, 1, 12-diaminododecane, 1, 5-pentanediamine, cyclohexanediamine, methylcyclohexanediamine, tetramethylp-phenylenediamine, or dimethyldiphenyldiamine, preferably any one or a combination of at least two of m-xylylenediamine, p-xylylenediamine, 1, 3-cyclohexyldimethylamine, 1, 4-butanediamine, 1, 6-hexanediamine, MDA, and the like, 1, 4-diaminocyclohexane, diaminodicyclohexylmethane (for example, industrial H)₁₂MDA which is any one or a combination of at least two of 4, 4-diaminodicyclohexylmethane, 2-diaminodicyclohexylmethane, and the like), isophoronediamine, 1, 8-octanediamine, 1, 10-decanediamine, 1, 12-diaminododecane, 1, 5-pentanediamine, cyclohexanediamine, methylcyclohexanediamine, tetramethylp-phenylenediamine, dimethyldiphenyldiamine, 1, 6-hexanediamine, diaminodicyclohexylmethane, toluenediamine, phenylenediamine, or naphthalenediamine.

Preferably, the phosgene-based raw material is in excess.

Preferably, the phosgene-based raw material comprises any one or at least two combinations of phosgene, diphosphine, triphosgene, fluorophosphone or bromophosgene, preferably one or at least two combinations of phosgene, diphosphine, triphosgene and fluorophosphone, and more preferably phosgene and/or fluorophosphone.

Preferably, the preparation method further comprises: and carrying out post-treatment on a crude product obtained by the phosgene reaction.

Preferably, the phosgenation reaction comprises a gas phase phosgenation reaction, a liquid phase phosgenation reaction or a salt forming phosgenation reaction.

The phosgenation reaction of the present invention may be carried out using process types known in the art. According to the method provided by the invention, in some examples, the phosgenation reaction is selected from gas-phase phosgenation reaction, liquid-phase phosgenation reaction or salifying phosgenation reaction, and different measures are needed to control the content of alkaline chlorine in different phosgenation reaction processes.

Preferably, the gas phase phosgenation reaction includes: the polyamine gas flow and the phosgene raw material are subjected to gas phase phosgenation reaction, the reaction product is mixed with a liquid inert medium and cooled to the temperature of less than or equal to 150 ℃, or the reaction product is mixed with a mixture of the liquid inert medium and a target isocyanate product and cooled to the temperature of less than or equal to 150 ℃, such as 50 ℃, 60 ℃, 70 ℃, 80 ℃, 90 ℃, 100 ℃, 110 ℃, 120 ℃, 130 ℃, 140 ℃, 150 ℃ and the like, preferably 100 ℃ and 140 ℃, so as to obtain a crude isocyanate product.

In the preferred technical scheme of the invention, because the temperature of the reaction mixed gas is higher and the generation of the alkaline chlorine is controlled, the temperature of the reaction mixed gas after being absorbed and cooled by the liquid inert medium and/or the mixture of the inert medium and the isocyanate is required to be less than or equal to 150 ℃ so as to reduce the generation amount of the alkaline chlorine.

For illustrative purposes, said gas phase phosgenation reactions can be found in particular in patent applications CN102260194A, CN 105214568A. In some embodiments, the step of gas phase phosgenation reaction comprises: 1) gasifying the polyamine to form a polyamine gas stream, the polyamine gas stream containing polyamine droplets; 2) removing polyamine droplets contained in the polyamine gas stream to obtain a polyamine gas stream substantially free of polyamine droplets; 3) and (3) carrying out gas-phase phosgenation on the polyamine gas stream which is basically free of polyamine liquid drops and a phosgene raw material, mixing the reaction product with a liquid inert medium (such as an aromatic solvent) and rapidly cooling to 140 ℃ in a gas jet absorption device, or mixing the reaction product with a mixture of the liquid inert medium and the target isocyanate product and rapidly cooling to 140 ℃ in the gas jet absorption device to obtain a crude isocyanate product. Simultaneously, removing polyamine liquid drops contained in the polyamine gas flow by using a heater; for example, the specific structure of the heater can be found in the corresponding disclosure of patent application CN 105214568A. The temperature of the gas phase phosgenation reaction is, for example, 200-; the pressure of the reaction is 0.01 to 1MPa (e.g., 0.05MPa, 0.08MPa, 0.2MPa, 0.5MPa, 0.8MPa), preferably 0.03 to 0.3 MPa. In some embodiments, the mixed gas (reaction product) after the reaction of the phosgene-based raw material and the polyamine may be subjected to absorption cooling using a liquid inert medium (e.g., an aromatic solvent) and/or a mixture of the inert medium and the isocyanate.

Preferably, the liquid phase phosgene reaction comprises: the polyamine solution and the phosgene raw material are firstly subjected to cold reaction at 0-100 ℃ and then are subjected to hot reaction at 60-180 ℃, and the total residence time of the cold reaction and the hot reaction is less than or equal to 7 hours, such as 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours and the like.

In the preferred technical scheme of the invention, the total residence time of the cold reaction and the hot reaction is controlled within 7h, so that the generation of alkaline chlorine can be controlled.

Said liquid phase phosgenation reaction can be found, for example, in patent application CN 103319372A. In some embodiments, the liquid phase phosgenation reaction is carried out in two steps: 1) cold reacting at 0-100 deg.C, preferably 40-70 deg.C; the pressure is 0.1-1 MPa; mixing polyamine with aromatic solvent (one or more selected from chlorobenzene, m-dichlorobenzene, o-dichlorobenzene, p-dichlorobenzene and chlorotoluene) to obtain solution, and reacting with super-stoichiometric phosgene raw material for 2-120min, preferably 5-45 min. 2) The thermal reaction is carried out at the temperature of 60-180 ℃, preferably at the temperature of 110-165 ℃ and more preferably at the temperature of 120-150 ℃; the pressure is 0.1-1 MPa; one or more of chlorobenzene, m-dichlorobenzene, o-dichlorobenzene, p-dichlorobenzene and chlorotoluene is used as a solvent to react with the super-stoichiometric phosgene raw material, and the reaction residence time can be 0.5-5 h. In the liquid phase phosgenation process, the total residence time of cold reaction and hot reaction is less than or equal to 7h for controlling the generation of alkaline hydrolysis chlorine.

Preferably, the salt-forming phosgenation reaction includes: hydrogen chloride and/or carbon dioxide and polyamine are subjected to salt forming reaction in an inert solvent, and then are subjected to phosgenation reaction with phosgene raw materials; the total residence time of the salification reaction and the phosgenation reaction is less than or equal to 7h, such as 1h, 2h, 3h, 4h, 5h, 6h, 7h and the like.

In the preferred technical scheme of the invention, the total residence time of the salification reaction and the phosgenation reaction is controlled within 7h, and the generation of alkaline chlorine hydride can be controlled.

Said phosgenation reaction can also be carried out, for example, in hydrogen chloride and/or carbon dioxide, i.e. a salt-forming phosgenation reaction, see in particular patent applications CN105218422A, CN 107337615 a. In some embodiments, the salt-forming phosgenation reaction step is: 1) performing salt formation reaction on hydrogen chloride and/or carbon dioxide and polyamine in an inert solvent, wherein the molar equivalent ratio of the hydrogen chloride to amino groups in the polyamine is 1-2.5:1, preferably 1.2-2:1, the molar equivalent ratio of the carbon dioxide to the amino groups in the polyamine is 0.5-5:1, preferably 0.6-3:1, and the mass ratio of the inert solvent to the polyamine is 25-5:1, preferably 20-5: 1; the temperature of the salt forming reaction is 0-50 ℃, preferably 5-30 ℃, and the pressure is 0.1-1MPa absolute, preferably 0.2-0.5MPa absolute; the reaction residence time is 1-15min, preferably 5-10 min. After the salt forming reaction in the step 1), the reaction liquid of the obtained hydrochloride or carbonate enters the step 2) to carry out the phosgenation reaction with the phosgene raw material; the reaction temperature is 100-170 ℃, preferably 110-165 ℃, and more preferably 120-150 ℃; the reaction pressure is 0.1-1MPa absolute pressure, preferably 0.2-0.5MPa absolute pressure; reacting with super-stoichiometric phosgene raw materials, wherein the reaction residence time can be 1-8 h. Wherein the inert solvent is selected from one or more of chlorobenzene, m-dichlorobenzene, o-dichlorobenzene, p-dichlorobenzene and chlorotoluene. In the salifying phosgenation process, in order to control the generation of alkaline hydrolysis chlorine, the total retention time in the step 1) and the step 2) is less than or equal to 7 h.

Regardless of the liquid phase, salt formation or gas phase phosgenation process, after the reaction is finished, the reaction solution can be filtered and subsequently separated according to the requirements. According to the known technology in the field, a rectifying tower or a stripping tower is generally adopted to remove byproduct hydrogen chloride and excess phosgene raw materials in reaction liquid, and the phosgene raw materials can be conveyed back to a reaction system for recycling after being refined; removing the solvent in the reaction liquid by using a rectifying tower, and conveying the refined solvent back to the reaction system for recycling; a crude polyisocyanate composition stream substantially free of solvent is obtained by isolation. And (3) separating and refining the crude polyisocyanate composition flow by adopting a scraper evaporator or a rectifying tower, and removing impurities of non-volatile components (tar) and light components with low boiling points to obtain the corresponding polyisocyanate composition.

The third object of the present invention is to provide a polyurethane resin, which is prepared from a combination of the polyisocyanate composition described in one of the objects and a compound having an active hydrogen group.

The polyurethane resin in the present invention is a reaction product of a polyisocyanate component in a polyisocyanate composition and a compound having an active hydrogen group. The emulsion obtained in the synthesis process of the polyurethane resin provided by the invention has low turbidity, and the polyurethane product has high light transmittance, yellowing resistance and heat resistance.

Preferably, the compound containing an active hydrogen group includes a polyol compound and/or an amine compound. The polyol compound is a compound having at least two hydroxyl groups.

Preferably, the molecular weight of the polyol compound is 400-.

Preferably, the polyol compound has a hydroxyl value of 10mg KOH/g to 1500mg KOH/g, such as 20mg KOH/g, 30mg KOH/g, 40mg KOH/g, 50mg KOH/g, 100mg KOH/g, 200mg KOH/g, 500mg KOH/g, 800mg KOH/g, 1000mg KOH/g, 1200mg KOH/g, 1400mg KOH/g, and the like. The hydroxyl value of the polyol component can be determined by analysis according to the A-phthalic anhydride method of GB/T12008.3-2019 standard.

Preferably, the polyol-based compound has a functionality of 2 to 8, such as 3, 4, 5, 6, 7, and the like.

Preferably, the polyol compound includes any one or a combination of at least two of polyether polyol, polyester polyol, polyolefin polyol, epoxy resin, or bio-based polyol.

Preferably, the polyether polyol comprises any one or a combination of at least two of polyoxyethylene polyol, polyoxypropylene polyol, polymer polyol, polyurea polyol, polytetrahydrofuran and copolyether glycols thereof, polytrimethylene glycol or aromatic polyether polyol.

Preferably, the polyester polyol comprises any one or at least two of adipic acid polyester diol, aromatic polyester polyol, polycaprolactone polyol or polycarbonate diol.

Preferably, the adipic acid-based polyester diol comprises any one of or a combination of at least two of polyethylene adipate diol, polypropylene adipate diol, polybutylene adipate diol, or polyethylene adipate diol diethylene glycol.

Preferably, the aromatic polyester polyol comprises any one or at least two of polyethylene terephthalate glycol, 1, 6-hexanediol phthalate glycol, or neopentyl glycol phthalate glycol.

Preferably, the polycaprolactone polyol comprises a polycaprolactone diol and/or a polycaprolactone triol.

Preferably, the polycarbonate diol comprises any one of or at least two combinations of polyhexamethylene carbonate diol, poly-1, 6-hexanediol carbonate diol, or polybutylece carbonate diol.

Preferably, the polyolefin polyol includes any one or a combination of at least two of hydroxyl-terminated polybutadiene, hydroxyl-terminated hydrogenated polybutadiene, hydroxyl-terminated epoxidized polybutadiene resin, hydroxyl-terminated polybutadiene-acrylonitrile, or polystyrene polyol.

Preferably, the epoxy resin comprises any one or at least two of bisphenol A epoxy resin, bisphenol F epoxy resin, novolac epoxy resin or aliphatic epoxy resin.

Preferably, the bio-based polyol comprises any one or a combination of at least two of castor oil and its derivative polyol, soybean oil polyol, palm oil polyol, rosin ester polyol, fatty acid dimer diol, fish oil polyol or lignin polyol.

Preferably, the raw materials for preparing the polyurethane resin further comprise a catalyst and/or a chain extender.

Preferably, the chain extender includes any one or a combination of at least two of a polyfunctional alcohol compound (e.g., having a functionality of 2, 3, 4, 5) and/or a polyfunctional amine compound (e.g., having a functionality of 2, 3, 4, 5), preferably ethylene glycol, diethylene glycol (diethylene glycol), 1, 2-propylene glycol, dipropylene glycol, 1,4-butanediol (1,4-butanediol, BDO), 1, 6-Hexanediol (HD), Trimethylolpropane (TMP), castor oil, Ethylenediamine (EDA), hydrazine, hexamethylenediamine, isophoronediamine, methylpentanediamine, diethylenetriamine, or triethylenetetramine.

In the field of aqueous polyurethane, the chain extender used is a hydrophilic chain extender, preferably any one or a combination of at least two of dimethylolpropionic acid (DMPA), dimethylolbutyric acid (DMBA), 1, 4-butanediol-2-sodium sulfonate, diethanolamine, triethanolamine, N-Methyldiethanolamine (MDEA), N-ethyldiethanolamine (EDEA), N-Propyldiethanolamine (PDEA), N-Butyldiethanolamine (BDEA), dimethylethanolamine, bis (2-hydroxyethyl) aniline (BHBA), bis (2-hydroxypropyl) aniline (BHPA) and N-Methyldiethanolamine (MDEA).

In the present invention, the polyurethane resin can be produced by a process route known in the art, for example, a one-shot method and a prepolymer method, and in the present invention, it is preferable to carry out polymerization by a prepolymer method.

The one-shot method is a preparation method in which raw materials required for a polyisocyanate (e.g., an alicyclic diisocyanate composition), a polyol, a catalyst, a chain extender, and the like are uniformly mixed at one time and cast.

In the prepolymer method, a polyol and a slightly excessive polyisocyanate (such as an alicyclic diisocyanate composition) are reacted to synthesize a polyurethane prepolymer with two end groups being blocked by isocyanate groups, and then the prepolymer is further reacted with a catalyst and a chain extender to be cured and cast to form the polyurethane elastomer material.

In one embodiment of the present invention, the preparation of the polyurethane resin by a prepolymer method comprises the following steps:

1) preparing a polyurethane prepolymer with two end-capped isocyanate groups by performing prepolymerization reaction on the polyol and an excessive amount of the alicyclic diisocyanate composition; preferably, the prepolymerization reaction temperature is 60-120 ℃, preferably 80-100 ℃, and the reaction time is 1-6h, preferably 2-4 h;

2) mixing the polyurethane prepolymer with a catalyst and a chain extender, and pouring and curing to obtain the polyurethane resin; preferably, the pouring and curing are carried out at the temperature of 50-100 ℃, preferably 60-80 ℃, and the curing time is 1-10 hours, preferably 3-6 hours.

In some embodiments, the raw material formula used in the prepolymer method of the present invention comprises the following raw materials in parts by mass: 50-500 parts of polyisocyanate composition, preferably 100-400 parts; 100 parts of polyol; 50-500 parts of chain extender, preferably 50-400 parts; 0.005-1 part of catalyst, preferably 0.01-0.5 part.

The chain extender may be any one conventionally used in the art, for example, in some embodiments, the chain extender of the present invention may be a bifunctional compound such as diols including 1,4-butanediol, ethylene glycol, diethylene glycol, 1, 6-hexanediol, etc., diamines such as 3,3 '-dichloro-4, 4' -diphenylmethane diamine (MOCA), 3, 5-diethyltoluene diamine (DETDA), etc., ethanolamine, etc., or a trifunctional and higher compound such as glycerol, trimethylolpropane, pentaerythritol; 1,4-butanediol and/or 3,3 '-dichloro-4, 4' -diphenylmethanediamine are preferred in the present invention.

In the process of preparing the polyurethane resin, the content of the isocyanate group in the prepared isocyanate-terminated prepolymer can be subjected to titration analysis by using a method specified in GB/T12009.4-1989 standard.

The amount of chain extender may be calculated with reference to the method provided in patent application CN 110982038A; the chain extender of the present invention preferably has a chain extension coefficient of 0.8 to 1.1, more preferably 0.9 to 1.0.

The catalyst used in the prepolymer method is generally an organic tin compound, and examples thereof include one or more of stannous octoate, dibutyltin dichloride, dibutyltin dilaurate, dibutyltin diacetate and dibutyltin dilauryl sulfide, with dibutyltin dilaurate being preferred in the process route of the present invention.

In the production of the polyurethane resin of the present invention, additives known in the industry, for example, a plasticizer, an antifoaming agent, a flame retardant, a dehydrating agent, an antioxidant, an ultraviolet absorber, a hydrolysis preventing agent, a weather resistant stabilizer, and the like may be further added in an appropriate ratio according to the specific application.

The fourth object of the present invention is to provide a use of the polyurethane resin of the third object for the preparation of polyurethane elastomers, polyurethane optical materials, polyurethane coating materials (e.g., paints, adhesives) or polyurethane foams, preferably for the preparation of polyurethane elastomers.

Compared with the prior art, the invention has the following beneficial effects:

the invention provides a polyisocyanate composition containing a specific amount of alkaline chlorine hydride, which can dissociate chlorine hydride in the alkaline chlorine hydride to poison a catalyst when local violent heat release is caused when local runaway occurs in the reaction, so as to reduce the reaction activity of a local excessive reaction area, thereby avoiding the turbidity of polyurethane synthetic emulsion and further improving the light transmittance and yellowing resistance of a polyurethane product.

Detailed Description

The technical solution of the present invention is further explained by the following embodiments. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitations of the present invention.

Example 1

This example provides a polyisocyanate composition prepared as follows:

a) hexamethylenediamine (HDA) is gasified and heated to 355 ℃ using the heater disclosed in example 1 of patent application CN105214568A, under the protection of nitrogen, and is continuously fed into the reactor with gaseous phosgene heated to 355 ℃ via respective feed pipes for the phosgenation reaction; the reaction pressure is 0.05MPa absolute pressure, and the reaction temperature is 360 ℃; wherein the feeding amount of HDA is 800Kg/h, and the feeding amount of gaseous phosgene is 3000 Kg/h; rapidly cooling the mixed gas obtained after the reaction to 100 ℃ by adopting an o-dichlorobenzene solution through a gas jet absorption device (the contact time is about 10 s) to obtain a crude product containing the HDI, the phosgene and the o-dichlorobenzene solution;

and (3) absorbing the reaction tail gas in an o-dichlorobenzene solution at-35 ℃ after the reaction tail gas enters a tail gas absorption tower to obtain the o-dichlorobenzene solution containing phosgene.

b) Removing phosgene and an o-dichlorobenzene solution from the crude product obtained in the step a), removing the o-dichlorobenzene solution and excessive phosgene in the crude product at 168 ℃ and under the absolute pressure of 0.1MPa, and separating to obtain a crude HDI product without phosgene and an o-dichlorobenzene solution containing phosgene;

c) absorbing reaction tail gas in the step a) to obtain an o-dichlorobenzene solution containing phosgene, and feeding the o-dichlorobenzene solution containing phosgene obtained in the removing process in the step b) into a rectifying tower to separate the phosgene from the o-dichlorobenzene solution; the separation process is carried out under the conditions that the absolute pressure is 0.125MPa, the bottom temperature is 155 ℃ and the top temperature is 15 ℃ to obtain phosgene with the purity of 98 percent and o-dichlorobenzene solution with the phosgene content less than 0.001 percent, and the separated phosgene and o-dichlorobenzene solution are returned to the step a) for recycling;

d) and (c) purifying the HDI crude product which does not contain phosgene and is obtained in the step b) by a rectification mode, and obtaining an HDI (hexamethylene diisocyanate) product under the distillation ranges of 0.5KPa absolute pressure and 135-140 ℃.

The sum of the contents of the unsaturated olefin structure, secondary amine structure and hydroxyl structure in the hexamethylenediamine used was 200 ppm.

The yield of the HDI product obtained was 97%, and the purity of the product was 99.75%. The obtained product has 25ppm of hydrolytic chlorine, 30ppm of alkaline hydrolysis chlorine content and 5ppm of difference between the alkaline hydrolysis chlorine and the hydrolytic chlorine.

The embodiment also provides a polyurethane resin, and the preparation method thereof is as follows:

(1) preparation of polyurethane prepolymer

100 parts of polyoxypropylene glycol with the relative molecular mass of 1000, the hydroxyl value of 110mg KOH/g and the functionality of 2 (polyether polyol GE-210, Shanghai Gaoqiao petrochemical company) are weighed, heated to 110 ℃ while stirring, decompressed to the absolute pressure of 200Pa for removing water for 2.5 hours, cooled to 60 ℃, and 168 parts of HDI produced in the isocyanate synthesis process is added. Heating to 80 ℃, and reacting for 120min to obtain the blue transparent polyurethane prepolymer emulsion.

The prepolymer emulsion was subjected to turbidity test to give a turbidity of 0.42 NTU.

(2) And (2) placing the polyurethane prepolymer obtained in the step (1), 82 parts of 1,4-butanediol (BASF company, used after removing water for 2.5 hours at 102 ℃ under 200 Pa) and 0.1 part of dibutyltin dilaurate (Dabco T-12 in American air chemical industry) in a casting machine, respectively heating to 45 ℃, reducing the pressure to 1KPa under the absolute pressure to remove bubbles for 0.5 hour, uniformly mixing, casting into a mold preheated to 75 ℃, and heating and curing for 4 hours to obtain the polyurethane resin.

The obtained polyurethane product was subjected to a light transmittance test according to the method provided in GB/T2410-2008, and the result was 97.5%.

And (3) putting the prepared polyurethane resin into an oven at 80 ℃, and baking for 12h to obtain a dry polyurethane product. The color value b of the obtained polyurethane product was measured by a color difference meter (Alice X-Rite528 type), the polyurethane film was baked in an oven at 150 ℃ for 0.5 hour, the color value b of the resin film after baking was measured by a color difference meter and the color difference Delta E was measured to be 0.45 (the lower the value is, the more excellent the performance is), and the data shows that the polyurethane resin provided in this example has good yellowing resistance.

Example 2

This example provides a polyisocyanate composition prepared as follows:

the phosgenation reaction of step a) is carried out by liquid phase phosgenation, as disclosed in patent application CN103319372A, in a reaction vessel comprising:

1) and (3) cold reaction: 4,4' -diaminodicyclohexylmethane (H)₁₂MDA) is prepared into a solution with the mass content of 15 percent by taking o-dichlorobenzene as a solvent, preheated to 40 ℃, and simultaneously introduced into a reaction kettle containing an o-dichlorobenzene solution with liquid phosgene at the temperature of-5 ℃ for liquid phase phosgenation reaction; wherein H₁₂MDA feeding quantity is 400Kg/h, cold reacting phosgeneThe feeding amount of the reaction kettle is 1500kg/h, the cold reaction temperature is controlled at 60 ℃, and the retention time is 5 min;

2) thermal reaction: the temperature is controlled at 155 ℃, the retention time is 6 hours, and the reaction is carried out in the presence of o-dichlorobenzene solution and excessive phosgene to obtain the product H₁₂Reaction solution of MDI, phosgene and o-dichlorobenzene solution (crude product);

the total reaction residence time of the cold and hot phosgenation reaction stages is 6 hours and 5 minutes;

and (3) absorbing the reaction tail gas in an o-dichlorobenzene solution at the temperature of-30 ℃ after the reaction tail gas enters a tail gas absorption tower to obtain the o-dichlorobenzene solution containing phosgene.

b) Removing phosgene and o-dichlorobenzene solution from the reaction solution obtained in the step a), removing the o-dichlorobenzene solution and excessive phosgene in the reaction solution at 155 ℃ and under the absolute pressure of 0.05MPa, and obtaining H without phosgene₁₂Crude MDI and phosgene-containing ortho-dichlorobenzene solution;

in the removing process, the retention time of the phosgene-containing o-dichlorobenzene solution at 155 ℃ is controlled to be 1 h.

c) Absorbing reaction tail gas in the step a) to obtain an o-dichlorobenzene solution containing phosgene, and feeding the o-dichlorobenzene solution containing phosgene obtained in the removing process in the step b) into a rectifying tower to separate phosgene from o-dichlorobenzene; the separation process is carried out under the conditions that the absolute pressure is 0.125MPa, the bottom temperature is 145 ℃ and the top temperature is 15 ℃ to obtain the phosgene with the purity of 98 percent and the o-dichlorobenzene solution with the phosgene content less than 0.001 percent, and the separated phosgene and the o-dichlorobenzene solution are returned to the step a) for recycling.

d) Reacting the phosgene-free H obtained in step b)₁₂The crude MDI product is purified by rectification to obtain H under the absolute pressure of 0.5KPa and the distillation range of 150-160 DEG C₁₂MDI (dicyclohexylmethane diisocyanate) product.

H used₁₂The total content of unsaturated olefin structures, secondary amine structures and hydroxyl structures in the MDA was 270 ppm.

The yield of the H12MDI product obtained was 96% and the purity of the product was 99.8%. The obtained product has 5ppm of hydrolytic chlorine, 7ppm of alkaline hydrolysis chlorine content and 2ppm of difference between the alkaline hydrolysis chlorine and the hydrolytic chlorine.

(1) preparation of polyurethane prepolymer

Weighing 100 parts of polyoxypropylene glycol with the relative molecular mass of 1000, the hydroxyl value of 110mg KOH/g and the functionality of 2 (polyether polyol GE-210, Shanghai Gaoqiao petrochemical company), heating to 110 ℃ while stirring, decompressing to the absolute pressure of 200Pa for removing water for 2.5 hours, cooling to 60 ℃, adding 262 parts of H produced in the isocyanate synthesis process₁₂MDI. Heating to 85 ℃, and reacting for 100min to obtain the blue transparent polyurethane prepolymer emulsion.

The prepolymer emulsion was subjected to turbidity test to give a turbidity of 0.25 NTU.

(2) The polyurethane prepolymer obtained in step (1) was used to prepare a polyurethane resin according to the method of example 1, and the color difference Δ E test was performed, and the result was 0.31. The data show that the polyurethane resin provided by the present example has good yellowing resistance.

The obtained polyurethane product was subjected to a light transmittance test according to the method provided in GB/T2410-2008, and the result was 95.5%.

Example 3

This example provides a polyisocyanate composition prepared as follows:

the phosgenation reaction of step a) was carried out by salifying phosgenation, using the following steps in the tank reactor disclosed in example 1 of patent application CN 105218422A:

1) adding 1000Kg of o-dichlorobenzene as a reaction solvent in a salt-forming reaction kettle in advance, starting a circulating pump and stirring, feeding hydrogen chloride compressed gas into a reactor through a premixer at the speed of 50mol/min, stirring for 15min, heating the mixed solution of isophorone diamine (IPDA) and o-dichlorobenzene to 30 ℃ through a raw material preheater, and fully contacting hydrogen chloride gas at the flow rate of 335Kg/h to form salt for reaction; cooling with external circulation cooling water, removing part of reaction heat, and circulating liquid flow rate of 5m³About/h, maintaining the temperature of the reaction liquid at 30-45 ℃, stopping the mixed liquid of IPDA and o-dichlorobenzene after feeding for 1hFeeding, and continuously introducing HCl gas for 30 min.

2) Transferring the IPDA hydrochloride slurry obtained in the step 1) into a photochemical reaction kettle, wherein the photochemical reaction kettle is provided with a phosgene gas inlet pipe, and gas phase condensation reflux and stirring; heating a photochemical reaction kettle, starting stirring at the same time, introducing phosgene when the temperature reaches 60 ℃, wherein the phosgene feeding speed is 50mol/min, the reaction temperature is 145 ℃, and stopping phosgene feeding after a reaction liquid is clarified to obtain a salified photochemical reaction liquid (crude product) containing products IPDI, phosgene and o-dichlorobenzene;

the salifying reaction is carried out for 0.5h and the photochemical reaction is carried out for 6h, and the total reaction residence time in the salifying reaction and photochemical reaction stages is 6.5 h;

b) And c) removing phosgene and an o-dichlorobenzene solution from the reaction solution obtained in the step a), and removing the o-dichlorobenzene solution and excessive phosgene in the reaction solution at 145 ℃ and under the absolute pressure of 0.04MPa to obtain an IPDI (isophorone diisocyanate) crude product without phosgene and an o-dichlorobenzene solution containing phosgene.

c) Feeding the phosgene-containing o-dichlorobenzene solution obtained after the reaction tail gas is absorbed in the step a) and the phosgene-containing o-dichlorobenzene solution obtained in the gas removal process in the step b) into a rectifying tower for separating phosgene and o-dichlorobenzene; the separation process is carried out under the conditions that the absolute pressure is 0.125MPa, the bottom temperature is 165 ℃ and the top temperature is 15 ℃ to obtain the phosgene with the purity of 98 percent and the o-dichlorobenzene solution with the phosgene content less than 0.001 percent, and the separated phosgene and the o-dichlorobenzene solution are returned to the step a) for recycling.

d) The IPDI crude product which does not contain phosgene and is obtained in the step b) is purified by a rectification mode, and the IPDI (isophorone diisocyanate) product is obtained under the absolute pressure of 0.5KPa and the distillation range of 140 ℃ and 150 ℃.

The sum of the contents of unsaturated olefin structures, secondary amine structures and hydroxyl structures in the IPDA used was 170 ppm.

The yield of the IPDI product is 97.6%, and the purity of the product is 99.85%. The obtained product has 35ppm of hydrolytic chlorine, 41ppm of alkaline hydrolysis chlorine and 6ppm of difference between the alkaline hydrolysis chlorine and the hydrolytic chlorine.

(1) preparation of polyurethane prepolymer

Weighing 100 parts of polyoxypropylene glycol with the relative molecular mass of 1000, the hydroxyl value of 110mg KOH/g and the functionality of 2 (polyether polyol GE-210, Shanghai Gaoqiao petrochemical company), heating to 110 ℃ while stirring, decompressing to the absolute pressure of 200Pa for removing water for 2.5 hours, cooling to 60 ℃, adding 222 parts of H produced in the isocyanate synthesis process₁₂MDI. Heating to 85 ℃, and reacting for 150min to obtain the blue transparent polyurethane prepolymer emulsion.

The prepolymer emulsion was subjected to turbidity test to give a turbidity of 0.32 NTU.

(2) The polyurethane prepolymer obtained in step (1) is used for preparing a polyurethane resin according to the method of example 1, and a color difference Δ E test is performed, so that the result is 0.22, and the data show that the polyurethane resin provided by the example has good yellowing resistance.

The obtained polyurethane product was subjected to a light transmittance test according to the method provided in GB/T2410-2008, and the result was 96.7%.

Example 4

This example provides a polyisocyanate composition prepared as follows:

a) diamine IPDA was vaporized and heated to 355 ℃ using the heater disclosed in example 1 of patent application CN105214568A, and under the protection of nitrogen, phosgene was continuously fed into the reactor with gaseous phosgene heated to 355 ℃ via the respective feed lines for the phosgenation reaction; the reaction pressure is 0.05MPa absolute pressure, and the reaction temperature is 360 ℃; wherein the feeding amount of IPDA is 800Kg/h, and the feeding amount of gaseous phosgene is 3000 Kg/h; a chlorobenzene solution is adopted to rapidly cool the mixed gas obtained after the reaction (the contact time is about 10 s) to 105 ℃ through a gas jet absorption device, so as to obtain a crude product containing the product IPDI, phosgene and the chlorobenzene solution;

and (3) absorbing the reaction tail gas in a chlorobenzene solution at the temperature of-25 ℃ after the reaction tail gas enters a tail gas absorption tower to obtain a chlorobenzene solution containing phosgene.

b) And c) removing phosgene and a chlorobenzene solvent from the crude product obtained in the step a), and removing chlorobenzene and excessive phosgene in the crude product at 168 ℃ under the absolute pressure of 0.1MPa to obtain an IPDI (isophorone diisocyanate) crude product without phosgene and a chlorobenzene solution containing phosgene.

c) Absorbing reaction tail gas in the step a) to obtain a chlorobenzene solution containing phosgene, and feeding the chlorobenzene solution containing phosgene obtained in the removing process in the step b) into a rectifying tower to separate the phosgene from the chlorobenzene solution; the separation process is carried out under the conditions that the absolute pressure is 0.125MPa, the bottom temperature is 155 ℃ and the top temperature is 15 ℃ to obtain phosgene with the purity of 98 percent and chlorobenzene solution with the phosgene content less than 0.001 percent, and the separated phosgene and chlorobenzene solution are returned to the step a) for recycling.

d) The IPDI crude product which does not contain phosgene and is obtained in the step b) is purified by a rectification mode, and IPDI (isophorone diisocyanate) products are obtained under the absolute pressure of 0.5KPa and the distillation range of 140 ℃ and 150 ℃.

The yield of the IPDI product is 97.5%, and the purity of the product is 99.85%. The obtained product has 17ppm of hydrolytic chlorine, 22ppm of alkaline hydrolysis chlorine content and 5ppm of difference between the alkaline hydrolysis chlorine and the hydrolytic chlorine.

(1) preparation of polyurethane prepolymer

100 parts of polyoxypropylene glycol with the relative molecular mass of 1000, the hydroxyl value of 110mg KOH/g and the functionality of 2 (polyether glycol GE-210, Shanghai Gaoqiao petrochemical company) are weighed, heated to 110 ℃ while stirring, decompressed to the absolute pressure of 200Pa for removing water for 2.5 hours, cooled to 60 ℃, and 222 parts of IPDI produced in the isocyanate synthesis process is added. Heating to 85 ℃, and reacting for 150min to obtain the blue transparent polyurethane prepolymer emulsion.

The prepolymer emulsion was tested for turbidity to 0.19 NTU.

(2) The polyurethane prepolymer obtained in step (1) was used to prepare a polyurethane resin according to the method of example 1, and the color difference Δ E test showed that the polyurethane resin provided in this example has good yellowing resistance, and the result was 0.21.

The obtained polyurethane product was subjected to a light transmittance test according to the method provided in GB/T2410-2008, and the result was 94.9%.

Example 5

This example provides a polyisocyanate composition which was prepared by the same method as in example 1 except that the sum of the contents of the unsaturated olefin structure, secondary amine structure and hydroxyl structure in the hexamethylenediamine used was 50ppm, and the remaining operation steps and conditions were the same as in example 1.

The yield of the HDI product obtained was 97%, and the purity of the product was 99.75%. The obtained product has 25ppm of hydrolytic chlorine, 25.4ppm of alkaline hydrolysis chlorine and 0.4ppm of difference between the alkaline hydrolysis chlorine and the hydrolytic chlorine.

This example also provides a polyurethane resin prepared in the same manner as in example 1.

The turbidity of emulsion obtained by synthesizing the polyurethane prepolymer is 0.10 NTU; the color difference Δ E test of the obtained polyurethane resin was 0.09.

The obtained polyurethane product was subjected to a light transmittance test according to the method provided in GB/T2410-2008, and the result was 98.5%.

Example 6

This example provides a polyisocyanate composition which was prepared by the same method as in example 1 except that in step (a), the mixed gas obtained after the reaction was rapidly cooled (contact time was about 10 seconds) to 120 ℃ by using an o-dichlorobenzene solution through a gas jet absorption apparatus, and the remaining operation steps and conditions were the same as in example 1.

The yield of the HDI product obtained was 97% and the purity of the product was 99.8%. The obtained product has 23ppm of hydrolytic chlorine, 63ppm of alkaline hydrolysis chlorine and 40ppm of difference between the alkaline hydrolysis chlorine and the hydrolytic chlorine.

The turbidity of emulsion obtained by synthesizing the polyurethane prepolymer is 0.11 NTU; the obtained polyurethane resin was subjected to a color difference Δ E test, and the result was 0.10.

The obtained polyurethane product was subjected to a light transmittance test according to the method provided in GB/T2410-2008, and the result was 98.4%.

Example 7

This example provides a polyisocyanate composition which differs from that of example 2 only in the use of H₁₂The total content of the unsaturated olefin structure, the secondary amine structure and the hydroxyl structure in MDA was 120ppm, and the remaining operation steps and conditions were the same as in example 2.

The yield of the HDI product obtained was 96.2%, and the purity of the product was 99.8%. The obtained product has 4.1ppm of hydrolytic chlorine, 4.3ppm of alkaline hydrolysis chlorine and 0.2ppm of difference between the alkaline hydrolysis chlorine and the hydrolytic chlorine.

This example also provides a polyurethane resin prepared in the same manner as in example 2.

The turbidity of emulsion obtained by synthesizing the polyurethane prepolymer is 0.14 NTU; the obtained polyurethane resin was subjected to a color difference Δ E test, and the result was 0.15.

The obtained polyurethane product was subjected to a light transmittance test according to the method provided in GB/T2410-2008, and the result was 96.2%.

Example 8

This example provides a polyisocyanate composition prepared by the same process as in example 2 except that the total residence time for the reaction in the cold and hot phosgenation stages was 6 hours, with the cold reaction time being 5 minutes and the hot reaction time being 5 hours and 55 minutes, and the remaining operating steps and conditions were the same as in example 2.

Obtained H₁₂The yield of the MDI product was 96% and the purity of the product was 99.8%. The obtained product has 5ppm of hydrolytic chlorine, 65ppm of alkaline hydrolysis chlorine content and 60ppm of difference value between the alkaline hydrolysis chlorine and the hydrolytic chlorine.

The turbidity of emulsion obtained by synthesizing the polyurethane prepolymer is 0.15 NTU; the obtained polyurethane resin was subjected to a color difference Δ E test, and the result was 0.15.

The obtained polyurethane product was subjected to a light transmittance test according to the method provided in GB/T2410-2008, and the result was 96.0%.

Example 9

This example provides a polyisocyanate composition which is prepared by a process different from that of example 3 only in that IPDA is used in which the total content of the unsaturated olefin structure, the secondary amine structure and the hydroxyl structure is 180ppm, and the remaining operating steps and conditions are the same as those of example 3.

The yield of the IPDA product is 97.6 percent, and the purity of the product is 99.87 percent. The obtained product has the hydrolysis chlorine of 17.4ppm, the alkaline hydrolysis chlorine content of 17.5ppm and the difference between the alkaline hydrolysis chlorine and the hydrolysis chlorine of 0.1 ppm.

This example also provides a polyurethane resin prepared in the same manner as in example 3.

The turbidity of emulsion obtained by synthesizing the polyurethane prepolymer is 0.19 NTU; the obtained polyurethane resin was subjected to a color difference Δ E test, and the result was 0.18.

The obtained polyurethane product was subjected to a light transmittance test according to the method provided in GB/T2410-2008, and the result was 94.0%.

Example 10

This example provides a polyisocyanate composition prepared by the same method as in example 3 except that the total residence time of the salt-forming reaction, photochemical reaction stage was 6 hours, wherein the salt-forming reaction was 0.5 hour and the photochemical reaction was 5.5 hours, and the remaining operating steps and conditions were the same as in example 3.

The yield of the HDI product obtained was 97.5%, and the purity of the product was 99.88%. The obtained product had a chlorine hydrolysis of 17ppm, an alkaline chlorine content of 117ppm and a difference between alkaline chlorine and chlorine hydrolysis of 100 ppm.

The turbidity of emulsion obtained by synthesizing the polyurethane prepolymer is 0.19 NTU; the obtained polyurethane resin was subjected to a color difference Δ E test, and the result was 0.20.

The obtained polyurethane product was subjected to a light transmittance test according to the method provided in GB/T2410-2008, and the result was 94.8%.

Comparative example 1

This comparative example provides a polyisocyanate composition which was prepared by a method different from that of example 1 only in that in step a), the mixed gas obtained after the reaction was rapidly cooled (contact time was about 10 seconds) to 175 ℃ by using an o-dichlorobenzene solution through a gas jet absorption apparatus, and the remaining operation steps and conditions were the same as those of example 1.

The yield of the HDI product obtained was 97%, and the purity of the product was 99.74%. The obtained product has 23ppm of hydrolytic chlorine, 170ppm of alkaline hydrolysis chlorine content and 147ppm of difference between the alkaline hydrolysis chlorine and the hydrolytic chlorine.

This comparative example also provides a polyurethane resin, which was prepared in the same manner as in example 1.

The turbidity of emulsion obtained by synthesizing the polyurethane prepolymer is 1.7 NTU; the obtained polyurethane resin was subjected to a color difference Δ E test, and the result was 1.5.

The obtained polyurethane product was subjected to a light transmittance test according to the method provided in GB/T2410-2008, and the result was 81.5%.

Comparative example 2

This comparative example provides a polyisocyanate composition which is prepared by a process which differs from that of example 2 only in that in step a) the residence time for the cold reaction is 30min, the residence time for the hot reaction is 8h, the total residence time for the reaction in the cold and hot phosgenation stages is 8.5 h, and the remaining operating steps and conditions are the same as in example 2;

obtained H₁₂The yield of the MDI product was 96.2% and the purity of the product was 99.81%. The obtained product has 3ppm of hydrolytic chlorine, 170ppm of alkaline hydrolysis chlorine content and 167ppm of difference between the alkaline hydrolysis chlorine and the hydrolytic chlorine.

This comparative example also provides a polyurethane resin, which was prepared in the same manner as in example 2.

The turbidity of emulsion obtained by synthesizing the polyurethane prepolymer is 1.9 NTU; the obtained polyurethane resin was subjected to a color difference Δ E test, and the result was 1.7.

The obtained polyurethane product was subjected to a light transmittance test according to the method provided in GB/T2410-2008, and the result was 79.1%.

Comparative example 3

This comparative example provides a polyisocyanate composition which is prepared by a process which differs from that of example 3 only in that in step a) the total residence time of the salt-forming reaction, photochemical reaction stage is 9.5 hours, the remaining operating steps and conditions being identical to those of example 3.

The yield of the IPDI product is 97.4%, and the purity of the product is 99.86%. The obtained product had 25ppm of hydrolyzed chlorine, 131ppm of alkaline hydrolyzed chlorine and 106ppm of difference between alkaline hydrolyzed chlorine and hydrolyzed chlorine.

This comparative example also provides a polyurethane resin, which was prepared in the same manner as in example 3.

The turbidity of the emulsion obtained by synthesizing the polyurethane prepolymer is 0.67 NTU; the obtained polyurethane resin was subjected to a color difference Δ E test, and the result was 1.9.

The obtained polyurethane product was subjected to a light transmittance test according to the method provided in GB/T2410-2008, and the result was 85.5%.

Comparative example 4

This comparative example provides a polyisocyanate composition which was prepared by a method different from that of example 4 only in that the IPDA was used in which the total content of the unsaturated olefin structure, the secondary amine structure and the hydroxyl structure was 0.2ppm, and the remaining operating steps and conditions were the same as those of example 4.

The yield of the IPDI product is 97.4%, and the purity of the product is 99.85%. The obtained product has 21ppm of hydrolytic chlorine, 21ppm of alkaline hydrolysis chlorine content and 0ppm of difference between the alkaline hydrolysis chlorine and the hydrolytic chlorine.

This comparative example also provides a polyurethane resin, which was prepared in the same manner as in example 4.

The turbidity of emulsion obtained by synthesizing the polyurethane prepolymer is 0.75 NTU; the obtained polyurethane resin was subjected to a color difference Δ E test, and the result was 2.7.

The obtained polyurethane product was subjected to a light transmittance test according to the method provided in GB/T2410-2008, and the result was 73.2%.

By comparing example 1 with comparative example 1, example 2 with comparative example 2, example 3 with comparative example 3, example 4 and comparative example 4, it can be seen that the polyisocyanate composition provided by the present application, which contains a specific amount of alkali-hydrolyzable chlorine (difference from hydrolysis chlorine of 0.1ppm to 100ppm), can effectively avoid cloudiness of polyurethane synthetic emulsion, thereby improving light transmittance and yellowing resistance of polyurethane products.

It is understood from comparative examples 1 and 5 to 10 that when the mass content of the alkali hydrolyzable chlorine minus the mass content of the hydrolyzable chlorine in the polyisocyanate composition is 0.2ppm to 60ppm (examples 1 and 5 to 8), the cloudiness of the polyurethane synthetic emulsion can be further improved, the light transmittance and yellowing resistance of the product can be improved, and the effect is more excellent if the difference is within the range of 4ppm to 40ppm (examples 1 and 5 to 6).

The present invention is illustrated in detail by the examples described above, but the present invention is not limited to the details described above, i.e., it is not intended that the present invention be implemented by relying on the details described above. It should be understood by those skilled in the art that any modification of the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific modes, etc., are within the scope and disclosure of the present invention.

Claims

1. A polyisocyanate composition characterized in that the polyisocyanate composition has a value of 0.1ppm to 100ppm, calculated by subtracting the mass content of hydrolyzed chlorine from the mass content of alkali hydrolyzed chlorine;

2. Polyisocyanate composition according to claim 1, characterized in that the amount of alkaline hydrolysis chlorine minus the amount of hydrolysis chlorine in the polyisocyanate composition is from 0.2ppm to 60ppm, preferably from 0.4ppm to 40 ppm.

3. The polyisocyanate composition of claim 1 or 2, wherein the polyisocyanate composition comprises a combination of a polyisocyanate, an alkali-hydrolyzable chlorine-type impurity and a hydrolyzable chlorine-type impurity;

preferably, the polyisocyanate is a diisocyanate;

preferably, the polyisocyanate comprises any one or at least two of alicyclic diisocyanate, aromatic diisocyanate or chain diisocyanate in combination;

preferably, the polyisocyanate includes any one or a combination of at least two of dicyclohexylmethane diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, m-xylylene isocyanate, p-xylylene isocyanate, 1, 3-dimethylisocyanate cyclohexane, 1, 4-dimethylisocyanate cyclohexane, tetramethylene diisocyanate, pentamethylene diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, benzene diisocyanate, naphthalene diisocyanate, and cyclohexyl diisocyanate.

4. The polyisocyanate composition according to any one of claims 1 to 3, wherein the raw materials for the preparation of the polyisocyanate composition comprise a combination of polyamines and phosgene-based raw materials;

preferably, the total mass content of impurities having an unsaturated olefin-based structure, a secondary amine-based structure or a hydroxyl-based structure in the polyamine is 0.1ppm to 400 ppm.

5. A process for the preparation of the polyisocyanate composition according to any one of claims 1 to 4, characterized in that it comprises: polyamine and phosgene raw materials are subjected to phosgenation reaction to obtain the polyisocyanate composition.

6. The production method according to claim 5, wherein the phosgenation reaction includes a gas-phase phosgenation reaction, a liquid-phase phosgenation reaction, or a salt-forming phosgenation reaction;

preferably, the gas phase phosgenation reaction includes: carrying out gas-phase phosgenation reaction on polyamine gas flow and phosgene raw materials, mixing the reaction product with a liquid inert medium and cooling to the temperature of less than or equal to 150 ℃, or mixing the reaction product with a mixture of the liquid inert medium and a target isocyanate product and cooling to the temperature of less than or equal to 150 ℃, preferably 100-;

preferably, the liquid phase phosgene reaction comprises: carrying out cold reaction on a polyamine solution and a phosgene raw material at 0-100 ℃, and then carrying out hot reaction at 60-180 ℃, wherein the total residence time of the cold reaction and the hot reaction is less than or equal to 7 hours;

preferably, the salt-forming phosgenation reaction includes: hydrogen chloride and/or carbon dioxide and polyamine are subjected to salt forming reaction in an inert solvent, and then are subjected to phosgenation reaction with phosgene raw materials; the total residence time of the salification reaction and the phosgenation reaction is less than or equal to 7 h.

7. A polyurethane resin characterized in that a raw material for producing the polyurethane resin comprises a combination of the polyisocyanate composition according to any one of claims 1 to 4 and a compound having an active hydrogen group.

8. The polyurethane resin according to claim 7, wherein the compound having an active hydrogen group includes a polyol compound and/or an amine compound;

preferably, the molecular weight of the polyol compound is 400-;

preferably, the hydroxyl value of the polyol compound is 10mg KOH/g-1500mg KOH/g;

preferably, the functionality of the polyol compound is 2 to 8.

9. The polyurethane resin according to claim 7 or 8, wherein the raw materials for preparing the polyurethane resin further comprise a catalyst and/or a chain extender.

10. Use of a polyurethane resin according to any one of claims 7 to 9 for the preparation of polyurethane elastomers, polyurethane optical materials, polyurethane coating materials or polyurethane foams, preferably for the preparation of polyurethane elastomers.