CN110982038A

CN110982038A - Polyurethane resin and preparation method thereof

Info

Publication number: CN110982038A
Application number: CN201911378576.0A
Authority: CN
Inventors: 史培猛; 尚永华; 孙立冬; 孙积钊; 李建峰; 王鹏; 胡浩; 周琦; 朱付林
Original assignee: Wanhua Chemical Group Co Ltd
Current assignee: Wanhua Chemical Group Co Ltd; Wanhua Chemical Ningbo Co Ltd
Priority date: 2019-12-27
Filing date: 2019-12-27
Publication date: 2020-04-10
Anticipated expiration: 2039-12-27
Also published as: WO2021128791A1; CN110982038B

Abstract

The invention provides a polyurethane resin and a preparation method thereof, which solve the problems of poor heat resistance and poor optical transparency commonly existing in the conventional polyurethane resin, particularly polyurethane elastomer. The preparation method is used for preparing the polyurethane resin by reacting an alicyclic diisocyanate composition and a polyol, wherein the content of a substance A contained in the alicyclic diisocyanate composition is controlled to be less than or equal to 0.5 wt%, and the substance A has a structure shown in the following general formula (I):

wherein R is₁Is a halogen atom; r₂、R₃、R₄Each independently is a hydrogen atom, an alkane group of C1-C8 or a cycloalkane group of C3-C8; r₅Is isocyanate group or isocyanic acid methyl group.

Description

Polyurethane resin and preparation method thereof

Technical Field

The invention relates to a method for preparing polyurethane resin by using an alicyclic diisocyanate composition and a polyol to react, in particular to polyurethane resin with good heat resistance and optical transparency and a preparation method thereof.

Background

The polyurethane resin material is prepared by reacting isocyanate and polyol, can be processed into polyurethane foam plastics, polyurethane fibers, polyurethane rubber and elastomers, polyurethane coatings, adhesives and the like, and is widely applied to various fields of home furnishing, buildings, daily necessities, traffic, household appliances and the like.

The polyurethane elastomer has a structure comprising a hard segment formed by an isocyanate part and a soft segment formed by a polyol part, so that the polyurethane elastomer can endow the material with excellent performances such as high strength, high toughness, wear resistance, oil resistance and the like through the design of molecular chains, and has high elasticity of rubber and rigidity of plastics.

The polyurethane elastomer material is limited by the formula and the process structure, generally has the defects of poor heat resistance and poor optical transparency, is easy to age, soften and deform when working at a higher temperature, and causes the reduction of mechanical strength, and the common polyurethane elastomer has the long-term use temperature of not more than 80 ℃, the short-term use temperature of not more than 120 ℃, and the poor optical transparency, thereby seriously influencing the application and popularization of the polyurethane elastomer material.

The following patents report the related research on the improvement of heat resistance of polyurethane elastomers.

Patent CN109181277A improves hydrolysis resistance and heat resistance of polyurethane elastomer by adding hydrolysis resistant agent and heat resistant additive, but the addition of additive has adverse effect on optical transparency of elastomer.

In patent CN108948725A, the polyurethane elastomer material, butadiene rubber and modified basalt fiber are mixed and modified to obtain a heat-resistant and wear-resistant modified polyurethane elastomer material, the basalt fiber modification process is complex, and does not utilize industrial popularization, and the mixing process affects the final optical transparency of the product.

In patent CN107325261A and CN 107880243A, the heat resistance of the polyurethane elastomer is improved by using aromatic diisocyanate to prepare the modified polyurethane elastomer, but the polyurethane product is easy to yellow, which affects the optical transparency and limits the downstream application of the product.

The technical scheme for improving the heat resistance of the polyurethane elastomer mainly comprises the steps of using aromatic diisocyanate as a base material, adding a modifier, mixing with other materials and the like, wherein certain negative effects can be caused on the optical transparency of the polyurethane elastomer while the heat performance is improved, and the inevitable defects exist.

Disclosure of Invention

The invention aims to solve the problems of poor heat resistance and poor optical transparency of the conventional polyurethane resin, particularly the polyurethane elastomer. The present invention provides a method for producing a polyurethane resin such as a polyurethane elastomer excellent in heat resistance and optical transparency based on an alicyclic diisocyanate composition.

In order to realize the purpose of the invention, the invention provides the following technical scheme:

the invention provides a preparation method of polyurethane resin, which is prepared by the reaction of alicyclic diisocyanate composition and polyol, wherein the content of substance A contained in the alicyclic diisocyanate composition is controlled to be less than or equal to 0.5 wt%, and the substance A has the following general formula (I):

wherein R is₁Is a halogen atom; r₂、R₃、R₄Each independently is a hydrogen atom, an alkane group of C1-C8 or a cycloalkane group of C3-C8; r₅Is isocyanate group or isocyanatomethyl (i.e. O ═ C ═ N-CH)₂-)。

According to the above general formula (I), R₂、R₃、R₄、R₅The position on the six-membered ring being arbitrary and may be, for example, R₁Ortho, meta or para, R₂、R₃、R₄、R₅May be attached to different C-atoms of the six-membered ring of formula (I) or wherein two groups are attached to the same C-atom of the six-membered ring.

R₁The halogen atom in (1) is, for example, Cl, Br; r₂、R₃、R₄The C1-C8 alkyl group is, for example, methyl or isobutyl, and the cycloalkyl group is, for example, cyclohexylmethyl.

The present inventors have conducted long-term studies on the preparation of a polyurethane resin excellent in heat resistance and optical transparency, and as a result, have found that, when a polyurethane resin such as a polyurethane elastomer is prepared using an alicyclic diisocyanate composition, the content of the substance a has a significant influence on the properties of the polyurethane elastomer prepared.

The content of the substance A of 0.5 wt% or less means that the total content of the substances satisfying the general formula (I) is controlled to 0.5 wt% or less, the substances satisfying the general formula (I) are not particularly limited, and specific compounds thereof may vary depending on the composition of the alicyclic diisocyanate composition as long as the substances satisfying the general formula (I) are included, and the impurities satisfying the general formula (I) are, for example, but not limited to, one or more of the substances represented by the following structural formulae, and it is to be noted that the impurities of the alicyclic diisocyanate composition to be controlled (substance A) of the present invention are exemplified herein and not meant to be limited thereto:

the present inventors have found that when a substance a (i.e., an impurity satisfying the general formula (I)) contained in an alicyclic diisocyanate composition is a monoisocyanate compound containing halogen and a cyclohexane structure in the preparation of a polyurethane resin, the monoisocyanate functions as a chain stopper in the preparation of polyurethane from a polyisocyanate, and the steric crosslinking degree of polyurethane is reduced to some extent, thereby affecting the heat resistance of a final polyurethane elastomer product.

In addition, the cyclohexane structure has a boat-shaped conformation and a chair-shaped conformation, and 6 carbon atoms in the cyclohexane structure have a flat bond and an upright bond, so that the space structure of the cyclohexane has high complexity. The inventor surprisingly finds that when a halogen atom is positioned on a cyclohexane six-membered ring of monoisocyanate containing a cyclohexane structure, namely the spatial configuration of the substance A is similar to that of diisocyanate, the substance A participates in building a polyurethane spatial structure, but the halogen atom does not have an unsaturated bond, and only occupies the position of an isocyanate group when building the polyurethane spatial structure, but cannot realize the function of chain extension, so that the spatial symmetry of polyurethane is reduced, and the optical transparency of a final polyurethane product is reduced. The present inventors have found that when the cycloaliphatic diisocyanate composition is used in an amount of > 0.5% by weight of the substance a, the heat resistance and optical transparency of the polyurethane resin produced by reacting the cycloaliphatic diisocyanate composition with a polyol are significantly adversely affected.

Therefore, by controlling the content of the substance A in the alicyclic diisocyanate composition to 0.5 wt% or less, a polyurethane resin, particularly a polyurethane elastomer, excellent in heat resistance and good in optical transparency can be obtained.

In some embodiments of the present invention, the cycloaliphatic diisocyanate composition contains said substance A in an amount of 0.5 wt.% or less, preferably 0.3 wt.% or less, more preferably 0.1 wt.% or less, and even more preferably 0.05 wt.% or less.

The content of the substance A can be determined by qualitative analysis using a GC and quantitative analysis using a GC in the following examples.

In some embodiments, the cycloaliphatic diisocyanate composition is one or more of dicyclohexylmethane diisocyanate (HMDI), isophorone diisocyanate (IPDI), cyclohexyldimethylene diisocyanate (HXDI), methylcyclohexyl diisocyanate (HTDI), cyclohexyl diisocyanate (CHDI). That is, in this embodiment, the cycloaliphatic diisocyanate composition refers to a combination of one or more of these materials, but does not preclude the presence of impurities therein, such as the material a.

Preferably, the cycloaliphatic diisocyanate composition is dicyclohexylmethane diisocyanate (HMDI), that is, dicyclohexylmethane diisocyanate is an essential component, since HMDI contains various isomers such as 2,4' -HMDI, 4,4' -HMDI, 2,2' -HMDI, etc., and a raw material containing various HMDI isomers is called a dicyclohexylmethane diisocyanate composition. In addition, the cycloaliphatic diisocyanate composition may simultaneously contain other cycloaliphatic polyisocyanates, such as one or more of isophorone diisocyanate (IPDI), cyclohexyl dimethylene diisocyanate (HXDI), methylcyclohexyl diisocyanate (HTDI), cyclohexyl diisocyanate (CHDI), without impairing the effects of the present invention. In addition, derivatives of these alicyclic diisocyanates, for example, isocyanurate-modified products, biuret-modified products, allophanate-modified products, polyol-modified products, carbodiimide-modified products, and the like of these alicyclic diisocyanates may be contained. When the above-mentioned dicyclohexylmethane diisocyanate is used in combination with another polyisocyanate and a modified product thereof, the combination ratio thereof is arbitrarily determined depending on the specific use of the resin produced by using the polyisocyanate composition. The polyisocyanate component in the production of the polyurethane resin of the present invention preferably contains the above-mentioned dicyclohexylmethane diisocyanate, and the use of the above-mentioned dicyclohexylmethane diisocyanate alone in the alicyclic diisocyanate composition is preferred from the viewpoint of producing a polyurethane elastomer having excellent heat resistance and good optical transparency.

As is well known to those skilled in the art, the cycloaliphatic diisocyanate composition may be obtained by phosgenating a cycloaliphatic diamine composition. Dicyclohexylmethanediisocyanate (HMDI) compositions prepared by phosgenating dicyclohexylmethanediamine (HMDA) compositions (HMDA comprising various isomers such as 2,4' -HMDA, 4,4' -HMDA, 2,2' -HMDA, and the like is referred to as dicyclohexylmethanediamine compositions) are preferably used in the present invention.

Cycloaliphatic diamines are usually prepared by catalytic hydrogenation of the corresponding aromatic amines, for example patents CN106631826B, CN108440311A, CN109851508A, CN110204447A disclose the preparation of dicyclohexylmethanediamine (HMDA) by catalytic hydrogenation of diphenylmethanediamine (MDA).

One of the causes of the generation of impurities (substance a) is: during the hydrogenation of the aromatic ring, there may be a small amount of incomplete hydrogenation, resulting in the occurrence of unsaturated double bond structures, such as the following unsaturated double bond-containing cyclohexene structures:

the two causes of impurities (substance a) are: a deamination reaction exists in the process route of preparing the alicyclic diisocyanate from the alicyclic diamine by a phosgenation method, and the removal of amino can cause the appearance of a cyclohexene structure. For example:

meanwhile, HCl is used as a byproduct in the process route for preparing isocyanate by a phosgenation method:

NH₂-R-NH₂+2COCl₂→NCO-R-NCO+4HCl

and the byproduct HCl and the carbon-carbon unsaturated double bond in the monoisocyanate with the cyclohexene structure containing the unsaturated double bond are subjected to addition reaction, so that the substance A is generated.

As the phosgenation method known to those skilled in the art, specifically, for example, a liquid-phase phosgenation method in which a dicyclohexylmethanediamine composition is reacted with phosgene in a liquid phase or a gas-phase phosgenation method in which a dicyclohexylmethanediamine composition is reacted with phosgene in a gas phase may be employed, and the present invention preferably employs a dicyclohexylmethanediisocyanate composition obtained by the gas-phase phosgenation method.

As known to those skilled in the art, the liquid phase phosgenation process comprises two steps, a cold phosgenation reaction, the main reaction of which is the formation of carbamoyl chlorides and amine hydrochlorides, and a thermal phosgenation reaction, the main reaction of which is the conversion of amine hydrochlorides to carbamoyl chlorides and the thermal decomposition of carbamoyl chlorides to isocyanates. The liquid phase phosgenation reaction can be carried out in any manner, and as is known to those skilled in the art, a single-stage or multi-stage stirred tank reactor is usually used, and the reactor feeding method may be dynamic mixing or static mixing feeding. In the cold light gasification reaction stage, an inert solvent is previously introduced into a reactor, the reaction pressure is adjusted to, for example, normal pressure or more, and, for example, 1.0MPa (gauge pressure) or less, preferably 0.4MPa (gauge pressure) or less, the temperature is controlled to, for example, 10 ℃ or more, and, for example, 100 ℃ or less, preferably 50 ℃ or less, phosgene is introduced in an amount of, for example, 2 times or more, and, for example, 12 times or less, preferably 10 times or less the stoichiometric amount of the dicyclohexylmethanediamine composition, and the dicyclohexylmethanediamine composition dissolved in the inert solvent is introduced. During this period, the reaction solution is maintained in a range of, for example, 10 ℃ or higher and, for example, 100 ℃ or lower, preferably 50 ℃ or lower, and the generated hydrogen chloride is discharged to the outside of the reactor through the reflux condenser. As the inert solvent, at least one of an aromatic hydrocarbon-based organic solvent and an ester-based organic solvent may be included.

Among them, the aromatic hydrocarbon-based organic solvent may be, for example, aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, etc.; the aromatic hydrocarbon-based organic solvent may also be specifically a halogenated aromatic hydrocarbon-based organic solvent such as chlorobenzene, dichlorobenzene, 1,2, 4-trichlorobenzene, or the like. The ester-based organic solvent may specifically be an aliphatic carboxylic acid ester and an aromatic carboxylic acid ester. Examples of the aliphatic carboxylic acid ester include amyl formate, isoamyl formate, hexyl formate, butyl acetate, amyl acetate, butyl stearate, butyl lactate, amyl lactate, and the like; examples of the aromatic carboxylic acid ester include benzyl formate, methyl salicylate, methyl benzoate, dimethyl phthalate, diethyl phthalate, dibutyl phthalate, and the like. These inert solvents may be used alone or in combination of 2 or more.

The amount of the inert solvent to be used is, for example, 500 parts by mass or more, preferably 800 parts by mass or more, for example 5000 parts by mass or less, preferably 1500 parts by mass or less, and more preferably 1000 parts by mass or less, per 100 parts by mass of dicyclohexylmethanediamine.

In the thermal phosgenation reaction stage, the reaction pressure is at normal pressure or higher, preferably at 0.1MPa (gauge pressure) or higher and, for example, at 1.2MPa (gauge pressure) or lower, preferably at 0.6MPa (gauge pressure) or lower, the reaction temperature is at 120 ℃ or higher and, for example, at 200 ℃ or lower, the reaction time is continued for, for example, at 1 hour or longer and, for example, at 5 hours or shorter, and when the reaction liquid is converted from a white slurry state to a clear transparent state, the reaction is completed and the reaction can be terminated.

The reaction of the gas phase phosgenation process can be carried out using a tubular reactor with mechanical stirring as disclosed in the art, or a tubular reactor with a microchannel type mixer, or a tubular reactor with a coaxial nozzle, with a tubular reactor with a coaxial nozzle being preferred in the present invention.

Diluting dicyclohexyl methane diamine composition by inert gas or inert solvent steam, heating to 200-600 ℃, preferably 300-500 ℃, heating phosgene to 200-600 ℃, preferably 300-500 ℃, introducing the diluted dicyclohexyl methane diamine composition and phosgene into a reaction tube, and carrying out gas-phase phosgenation reaction at 200-600 ℃, preferably 300-500 ℃.

The steam pressure of the diluted dicyclohexyl methane diamine composition is-0.08 to 1MPa (gauge pressure), preferably-0.06 to 0.6MPa (gauge pressure); the introducing pressure of phosgene is-0.08-1 Mpa (gauge pressure), preferably-0.06-0.6 Mpa (gauge pressure); the reaction pressure is-0.08 to 1MPa (gauge pressure), preferably-0.06 to 0.6MPa (gauge pressure).

The inert gas may be nitrogen or one or more combinations of argon or other noble gases, preferably nitrogen. The inert solvent vapor may be a vapor of toluene, xylene, chlorobenzene, dichlorobenzene, chloronaphthalene, decahydronaphthalene, preferably chlorobenzene vapor. The amount of the inert gas or the inert solvent steam is 0 to 50 percent, preferably 10 to 40 percent based on the molar amount of the dicyclohexylmethane diamine composition. The molar ratio of phosgene to dicyclohexylmethanediamine composition is 3:1 to 30:1, preferably 5:1 to 15: 1. The gas phase phosgenation reaction residence time is 0.01-30 seconds, preferably 0.05-20 seconds; the gas velocity in the reaction tube is maintained at 3m/s or more, preferably 10m/s or more, and more preferably 15 to 100 m/s.

At the outlet of the reaction tube, the mixed gas after the reaction of phosgene with the dicyclohexylmethanediamine composition is subjected to absorption cooling with a liquid inert medium and/or a mixture of an inert medium and isocyanate, and the technique of spray absorption cooling known in the art can be used. The temperature of the reaction mixture is cooled to 180 ℃ or lower, preferably 150 ℃ or lower, generally within 0.1 to 5 seconds, preferably 0.2 to 3 seconds. As liquid inert medium for the absorption cooling, all inert organic solvents suitable for the preparation of isocyanates can be used, and aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, etc., and also organic solvents based on halogenated aromatics such as chlorobenzene, dichlorobenzene, 1,2, 4-trichlorobenzene, etc., can be mentioned. An ester-based organic solvent may also be used, and may specifically be an aliphatic carboxylic acid ester such as amyl formate, isoamyl formate, hexyl formate, butyl acetate, amyl acetate, butyl stearate, butyl lactate or amyl lactate, etc.; it may also be an aromatic carboxylic acid ester such as benzyl formate, methyl salicylate, methyl benzoate, dimethyl phthalate, diethyl phthalate, dibutyl phthalate, etc. These inert solvents may be used alone or in admixture of 2 or more, and preferably the inert liquid is chlorobenzene, dichlorobenzene, toluene, xylene and/or mixtures thereof.

Regardless of the liquid phase phosgenation process or the gas phase phosgenation process, after the reaction is finished, the reaction solution can be filtered and subsequently separated as required. According to the technology known in the art, a rectifying tower or a stripping tower is generally adopted to remove byproduct hydrogen chloride and excess phosgene in reaction liquid, and the phosgene 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 dicyclohexylmethane diisocyanate composition stream substantially free of solvent is obtained by separation. And (3) separating and refining the crude dicyclohexylmethane diisocyanate composition flow by adopting a scraper evaporator or a rectifying tower, and removing impurities of nonvolatile components (tar) and light components with low boiling points to obtain the dicyclohexylmethane diisocyanate composition.

In the present embodiment, the content ratio of the substance a can be adjusted by purifying the alicyclic diisocyanate composition as needed, and the purification method is not particularly limited, and can be carried out by conventional industrial separation techniques such as distillation and crystallization, and distillation separation is preferable in the present invention. The content of the substance A contained in the alicyclic diisocyanate composition is controlled to be 0.5 wt% or less by purifying the alicyclic diisocyanate composition, for example, by rectification separation or crystallization separation.

The rectification separation is a conventional purification process in the art, and when the purification is performed by the rectification separation method, the rectification column may be a plate column or a packed column, and the rectification conditions may be appropriately set according to the content ratio of the substance a required in the purified alicyclic diisocyanate composition, and specifically, the number of theoretical plates in the rectification column is preferably 5 or more, more preferably 10 or more, and preferably 60 or less, and more preferably 30 or less. The column top pressure of the rectification column is preferably 0.05KPa or more, more preferably 0.1KPa or more, and preferably 2KPa or less, more preferably 0.5KPa or less. The reflux ratio of the rectifying column is preferably 0.05 or more, more preferably 0.5 or more, and preferably 50 or less, more preferably 30 or less. The column top temperature of the rectification column is preferably 100 ℃ or more, more preferably 120 ℃ or more, and preferably 180 ℃ or less, more preferably 160 ℃ or less. The column bottom temperature of the rectifying column is preferably 150 ℃ or higher, more preferably 170 ℃ or higher, and preferably 220 ℃ or lower, more preferably 205 ℃ or lower.

The alicyclic diisocyanate composition may be preheated by a preheater before it is purified by distillation in a distillation column, and the preheating temperature is preferably 120 ℃ or higher, more preferably 140 ℃ or higher, and preferably 180 ℃ or lower, more preferably 160 ℃ or lower.

The material rich in the substance A is extracted from the tower top, and the purified product is extracted from the side line of the rectifying tower. The overhead yield of the rectifying column is preferably 0.5 wt% or more, more preferably 1 wt% or more, and preferably 5 wt% or less, more preferably 3 wt% or less. The extraction amount of the heavy component-rich material at the bottom of the tower is preferably more than 0.5 wt%, more preferably more than 1 wt%, and preferably less than 5 wt%, more preferably less than 3 wt% of the material collection.

The proportion of said substances A contained in the cycloaliphatic diisocyanate composition can be adjusted according to the prior art separation techniques, for example with reference to the rectification process described above.

According to the specific application field, an anti-aging auxiliary agent can be added into the alicyclic diisocyanate composition to enhance the storage stability of the alicyclic diisocyanate composition and prolong the shelf life of the alicyclic diisocyanate composition, and the alicyclic diisocyanate composition is beneficial to realizing stable color number storage and difficult yellowing in the process of preparing polyurethane resin by using the alicyclic diisocyanate composition.

Examples of the anti-aging auxiliary include hindered phenol antioxidants, sulfonamide group-containing compounds, and organic phosphites, and preferably hindered phenol antioxidants such as antioxidant 264 (Tenox BHT, Eastman chemical Co., U.S.A.), antioxidant 245 (Irganox 245, BASF, Germany), and antioxidant 1076 (Irganox 1076, BASF, Germany) are used, and the amount of the anti-aging auxiliary added is generally 50 to 5000ppm, and preferably 100 to 1000 ppm.

In some embodiments, the polyol used in the present invention to prepare the polyurethane resin is a compound having a molecular weight of 400 or more, typically 20000 or less, having 2 or more hydroxyl groups, such as one or more of polyether polyol, polyester polyol, polyolefin polyol, epoxy resin, bio-based polyol. The above-mentioned polyol used for the preparation of the polyurethane may employ those commonly used in the art, and is not particularly required.

Examples of the polyether polyol include polyoxyethylene polyol, polyoxypropylene polyol, polymer polyol, polyurea polyol, polytetrahydrofuran and copolyether glycol thereof, polytrimethylene glycol, and aromatic polyether polyol.

Examples of the polyester polyol include adipic acid-based polyester diol, aromatic polyester polyol, polycaprolactone polyol, and polycarbonate diol. Examples of the adipic acid-based polyester diol include polyethylene adipate diol, polypropylene adipate diol, polybutylene adipate diol, and polyethylene adipate diethylene glycol; examples of the aromatic polyester polyol include polyethylene terephthalate glycol, 1, 6-hexanediol phthalate glycol, neopentyl glycol phthalate glycol ester glycol, and the like; the polycaprolactone polyols include, for example, polycaprolactone diols and polycaprolactone triols; the polycarbonate diol includes polyhexamethylene carbonate diol, 1, 6-hexanediol polycarbonate diol, and polybutylenecarbonate diol.

Examples of the polyolefin polyol include hydroxyl-terminated polybutadiene, hydroxyl-terminated hydrogenated polybutadiene, hydroxyl-terminated epoxidized polybutadiene resin, hydroxyl-terminated polybutadiene-acrylonitrile polystyrene polyol, and the like.

Examples of the epoxy resin include: bisphenol a epoxy resins, bisphenol F epoxy resins, novolac epoxy resins, aliphatic epoxy resins, and the like.

Examples of the bio-based polyol include castor oil and its derivative polyols, soybean oil polyols, palm oil polyols, rosin ester polyols, fatty acid dimer diols, fish oil polyols, lignin polyols, and the like.

These polyol components may be used alone or in combination of 2 or more.

The polyurethane resin of the present invention can be produced by reacting the alicyclic diisocyanate composition (polyisocyanate component) with at least one of the polyol components.

The polyol component used for producing the polyurethane resin of the present invention has a hydroxyl value of preferably 10mg KOH/g or more, more preferably 50mg KOH/g or more, preferably 1500mg KOH/g or less, more preferably 1000mg KOH/g or less, further preferably 500mg KOH/g or less, a molecular weight of preferably 400 or more, more preferably 800 or more, preferably 20000 or less, more preferably 5000 or less, and a functionality of 2 to 8, preferably 2 to 6.

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.

The polyurethane resin can be used for preparing polyurethane elastomers, polyurethane optical materials, polyurethane coating materials (such as coatings and adhesives) or polyurethane foams, and is preferably applied to the preparation of polyurethane elastomers. The polyurethane resin disclosed by the invention has excellent heat resistance and good optical transparency.

The polyurethane resin of the present invention can be produced by a process route known in the art, for example, a one-shot method and a prepolymer method, and the present invention is preferably produced by polymerization using a prepolymer method.

The reaction system for preparing the polyurethane resin can also comprise a catalyst and a chain extender.

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

The prepolymer method is to react polyol with slightly excessive polyisocyanate (namely alicyclic diisocyanate composition) to synthesize polyurethane prepolymer with two ends being blocked by isocyanate groups, and then the prepolymer is further reacted with a catalyst and a chain extender to be cured and cast for molding to obtain the polyurethane elastomer material.

The specific processes of the one-step method and the prepolymer method can be carried out by adopting the existing processes in the field. In some embodiments, the polyurethane resin is prepared by a prepolymer method, comprising the steps of:

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 ℃, and the reaction time is 1-6 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 ℃, and the curing time is 1-10 h.

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 the alicyclic diisocyanate composition, preferably 100-400 parts;

100 parts of the 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 conventionally used in the art, and for example, in some embodiments, the chain extender of the present invention may be a bifunctional compound such as diols such as 1, 4-butanediol, ethylene glycol, diethylene glycol, 1, 6-hexanediol, diamines such as 3,3 '-dichloro-4, 4' -diphenylmethanediamine (MOCA), 3, 5-diethyltoluenediamine (DETDA), 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 by GB/T12009.4-1989 standard, and can also be calculated according to the following formula:

in the above formula, the first and second carbon atoms are,

m_NCOcycloaliphatic diisocyanate combinationsThe addition amount of the substance, g;

m_OH-the amount of polyol added, g;

M_NCOthe molecular weight of the cycloaliphatic diisocyanate composition, g/mol;

M_OH-molecular weight of the polyol, g/mol;

42.02-molar mass of isocyanate groups.

The amount of bifunctional compound used as chain extender is calculated according to the following formula:

the theoretical addition of the chain extender is as follows:

m₂-amount of chain extender, g;

m_{performed polymer}The amount of prepolymer, g;

M_{chain extender}-molecular weight of chain extender, g/mol

f is chain extension coefficient.

When the trifunctional or above compound is used as the chain extender, the calculation can be carried out by referring to the formula.

The preferred chain extension coefficient of the present invention is 0.8 to 1.1, and 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 reaction process adopting the prepolymer method, the prepolymerization temperature is preferably 60-120 ℃, more preferably 80-100 ℃, and the prepolymerization time is preferably 1-6 h, more preferably 2-4 h; the casting curing temperature is preferably 50-100 ℃, more preferably 60-80 ℃, and the casting curing time is preferably 1-10 hours, more preferably 3-6 hours.

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 invention also provides a polyurethane resin prepared by the preparation method.

The technical scheme provided by the invention has the following beneficial effects:

according to the method of the present invention, the obtained polyurethane resin is excellent in heat resistance and good in optical transparency. The Vicat softening temperature of the obtained polyurethane resin is 125-145 ℃, and the light transmittance is 85-95%.

Detailed Description

In order to better understand the technical solution of the present invention, the following examples are further provided to illustrate the present invention, but the present invention is not limited to the following examples.

In the following examples and comparative examples, the content of the substance A in the diisocyanate composition was determined analytically by the following methods (GC-MS and GC analysis):

an analytical instrument: an Agilent 7890B-5977 gas chromatograph-mass spectrometer (Agilent corporation) is used for qualitative analysis of the substance A, and specific analysis conditions are as follows:

a chromatographic column: DB-5MS, (length 30m x inner diameter 0.25mm x film thickness 0.25 micron) (Agilent company);

chromatographic conditions are as follows:

temperature rising procedure: the initial temperature is 50 ℃, the temperature is increased to 100 ℃ at the speed of 5 ℃/min, then the temperature is increased to 290 ℃ at the speed of 10 ℃/min, and the constant temperature is kept for 40 min;

sample introduction amount: 1 mu L of the solution;

the split ratio is as follows: 30: 1;

sample inlet temperature: 280 ℃;

interface temperature: 250 ℃;

carrier gas: helium gas;

carrier gas flow: 1 ml/min;

mass spectrum conditions:

an Electron Impact (EI) ion source;

energy: 70 eV;

ion source temperature: 200 ℃;

transmission line temperature: 280 ℃;

mass scan range: m/z 20-500;

solvent retardation: 2.5 min.

An analytical instrument: agilent 7890B (Agilent) was used for quantitative analysis of the substance A, under the following specific analysis conditions:

a chromatographic column: DB-5, (length 30m x inner diameter 0.25mm x film thickness 0.25 μm) (Agilent company);

temperature rising procedure: heating from 120 ℃ to 220 ℃, heating at 10 ℃/min, keeping for 2min after reaching 220 ℃, and heating to 290 ℃ at 5 ℃/min;

the split ratio is as follows: 30: 1;

sample inlet temperature: 280 ℃;

sample introduction amount: 0.2 mu L;

detector temperature: 300 ℃;

carrier gas: n is a radical of₂；

Carrier gas flow: 1.5 ml/min;

the detection method comprises the following steps: FID.

Heat resistance of polyurethane resin: the Vicat softening temperature was tested according to GB/T1633-.

Optical transparency of urethane resin: the light transmittance was measured according to the method A-haze meter method in GB/T2410-2008 standard.

An example of purification of a cycloaliphatic diisocyanate composition to control the content of species a is illustrated below:

taking a rectification purification process of dicyclohexyl methane diisocyanate composition as an example to describe a control scheme of the content of the substance A, the dicyclohexyl methane diisocyanate composition used is a product of WANNATE HMDI made by Wanhua chemical group GmbH, and contains the following specific structure and content by GC-MS and GC analysis (as described above): :

the content is 0.3 wt%;

the content is 0.6 wt%;

0.1wt％。

the method comprises the following steps of performing rectification purification on the dicyclohexylmethane diisocyanate composition by using a filler type rectification tower, wherein the diameter of the tower is 50mm, the height of the filler is 1.5m, 304 stainless steel theta ring 5mm multiplied by 5mm filler is used, the number of tested theoretical plates is 25, the feeding position is 0.6m away from the bottom end of the filler, the lateral line extraction position is 1m away from the bottom end of the filler, the dicyclohexylmethane diisocyanate composition is preheated to 155 ℃, then is fed, the feeding speed is 10Kg/h, the pressure of the bottom of the tower is 500Pa, the temperature of the bottom of the tower is 195 ℃, the extraction amount of the bottom of the tower is 0.2Kg/h, the pressure of the top of the tower is 150Pa, the temperature of the top of the tower is 150 ℃, the reflux ratio is 8, the extraction amount of the top of the tower is 0.25Kg/h, the pressure of the lateral line extraction port is 230Pa, the extraction temperature is 180 ℃, the extraction amount is 9:

the content is 0.15 wt%;

the content is 0.3 wt%;

0.05wt％。

120ppm of antioxidant 264 (Eastman chemical company, Tenox BHT, USA) was added to the rectified and purified dicyclohexylmethane diisocyanate composition.

In this example, the content of the substance a in the dicyclohexylmethane diisocyanate composition before purification was 1 wt%, and the content of the substance a in the dicyclohexylmethane diisocyanate composition after rectification purification was 0.5 wt%; the person skilled in the art can, according to the conventional rectification techniques in hand, control the different contents of substance a in the dicyclohexylmethane diisocyanate composition by adjusting the rectification separation parameters in this embodiment. The content of the different substances a of the starting cycloaliphatic diisocyanate compositions used in the following examples can be controlled by means of rectification and separation, with reference to this example.

Example 1

In the examples, the parts are parts by mass (the same applies below).

(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 ℃, 265 parts of dicyclohexylmethane diisocyanate composition (product of WANNATE HMDI, produced by Wanhua chemical group Limited) is added, and the rectification and purification treatment are carried out according to the method, wherein the content of the substance A is 0.5 wt%. Heating to 80 ℃, reacting for 1.5 hours, sampling and determining the content of isocyanate groups to reach 21 percent of a preset value, and obtaining a polyurethane prepolymer;

(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 (polyurethane elastomer).

Example 2

A polyurethane elastomer was produced in the same procedure as in example 1, except that the dicyclohexylmethane diisocyanate composition used contained the substance A in an amount of 0.3% by weight.

Example 3

A polyurethane elastomer was produced in the same procedure as in example 1, except that the dicyclohexylmethane diisocyanate composition used contained the substance A in an amount of 0.1% by weight.

Example 4

A polyurethane elastomer was produced in the same procedure as in example 1, except that the dicyclohexylmethane diisocyanate composition used contained the substance A in an amount of 0.05% by weight.

Example 5

A polyurethane elastomer was produced in the same procedure as in example 1, except that the dicyclohexylmethane diisocyanate composition used contained the substance A in an amount of 0.03% by weight.

Example 6

A polyurethane elastomer was produced in the same procedure as in example 1, except that the dicyclohexylmethane diisocyanate composition used contained the substance A in an amount of 0.01% by weight.

Example 7

(1) Preparation of polyurethane prepolymer

100 parts of polycarbonate diol having a hydroxyl value of 55mg KOH/g and a functionality of 2 (polycarbonate polyol CD-220, Daiiol chemical Co., Ltd., Japan) with a relative molecular mass of 2000 were weighed, heated to 130 ℃ with stirring, reduced in pressure to an absolute pressure of 200Pa to remove water for 2.5 hours, cooled to 120 ℃, and added with 205 parts of an alicyclic diisocyanate composition obtained by mixing dicyclohexylmethane diisocyanate and cyclohexyldiisocyanate (dicyclohexylmethane diisocyanate is a product of No. WANNATE HMDI, 102 parts, purified by distillation, cyclohexyldiisocyanate is a product of DuPont, USA, 103 parts, purified by distillation), and the content of the substance A in the alicyclic diisocyanate composition was 0.5 wt%. Reacting for 1 hour, sampling and determining the content of isocyanate group to reach a predetermined value of 25 percent to obtain a polyurethane prepolymer;

(2) putting the polyurethane prepolymer obtained in the step (1), 242 parts of 3,3 '-dichloro-4, 4' -diphenylmethane diamine (New Material Ltd. in Hunan province, Suzhou, used after removing water at 102 ℃ under 200Pa absolute pressure for 2.5 hours) and 0.08 part of stannous octoate (American air chemical Dabco T-9) into a casting machine, respectively heating to 45 ℃, reducing the pressure to 1KPa absolute pressure to remove bubbles for 0.5 hour, uniformly mixing, casting into a mold preheated to 100 ℃, and heating and curing for 3 hours to obtain polyurethane resin (polyurethane elastomer).

Example 8

(1) Preparation of polyurethane prepolymer

100 parts of polycarbonate diol having a hydroxyl value of 55mg KOH/g and a functionality of 2 (polycarbonate polyol CD-220, Daiijue chemical Co., Ltd.) having a relative molecular mass of 2000 was weighed, heated to 130 ℃ with stirring, reduced in pressure to an absolute pressure of 200Pa to remove water for 2.5 hours, cooled to 60 ℃, and added with 164 parts of an alicyclic diisocyanate composition obtained by mixing dicyclohexylmethane diisocyanate and methylcyclohexyl diisocyanate (dicyclohexylmethane diisocyanate is a product of No. WANNATE HMDI, 82 parts of a product of Wanhua chemical Co., Ltd., distilled and purified, methylcyclohexyl diisocyanate is a product of DuPont, USA, 82 parts of the product is distilled and purified), and the content of the substance A in the alicyclic diisocyanate composition was 0.5 wt%. Reacting for 3 hours, sampling and determining the content of isocyanate groups to reach a preset value of 22 percent to obtain a polyurethane prepolymer;

(2) and (2) putting the polyurethane prepolymer obtained in the step (1), 62 parts of 1, 4-butanediol (BASF company, used after removing water for 2.5 hours at 102 ℃ under 200 Pa) and 0.06 part of dibutyltin diacetate (Dabco T-1 in American air chemical industry) into 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 50 ℃, and heating and curing for 10 hours to obtain the polyurethane resin (polyurethane elastomer).

Comparative example 1

A polyurethane elastomer was produced by following the same procedure as in example 1, except that the dicyclohexylmethane diisocyanate composition used was not purified, wherein the content of the substance A was 0.6% by weight.

Comparative example 2

A polyurethane elastomer was produced by following the same procedure as in example 1, except that the dicyclohexylmethane diisocyanate composition used was not purified, wherein the content of the substance A was 0.7% by weight.

Comparative example 3

A polyurethane elastomer was produced by following the same procedure as in example 1, except that the dicyclohexylmethane diisocyanate composition used was not purified, wherein the content of the substance A was 0.9% by weight.

Comparative example 4

A polyurethane elastomer was produced by following the same procedure as in example 1, except that the dicyclohexylmethane diisocyanate composition used was not purified, wherein the content of the substance A was 1% by weight.

Comparative example 5

A polyurethane elastomer was produced in the same procedure as in example 7, except that the cycloaliphatic diisocyanate composition obtained by mixing dicyclohexylmethane diisocyanate and cyclohexyl diisocyanate used was not purified, and the content of the substance A was 0.8% by weight.

Comparative example 6

A polyurethane elastomer was produced in the same procedure as in example 8, except that the cycloaliphatic diisocyanate composition obtained by mixing dicyclohexylmethane diisocyanate and methylcyclohexyl diisocyanate used was not purified, and the content of the substance A was 1% by weight.

The results of measuring the vicat softening temperature and the light transmittance of the polyurethane elastomers obtained in examples 1 to 8 and comparative examples 1 to 6 are shown in table 1:

TABLE 1

The polyurethane resin prepared by the process has excellent light transmittance, higher Vicat conversion temperature and good heat resistance; the polyurethane elastomer is particularly suitable for being used as a polyurethane elastomer, and can also be suitably used as various industrial products such as polyurethane optical materials, polyurethane coating materials (such as coatings and adhesives), polyurethane foams and the like.

It will be appreciated by those skilled in the art that modifications or adaptations to the invention may be made in light of the teachings of the present specification. Such modifications or adaptations are intended to be within the scope of the present invention as defined in the claims.

Claims

1. A method for producing a polyurethane resin by reacting an alicyclic diisocyanate composition with a polyol, characterized in that the content of a substance A contained in the alicyclic diisocyanate composition used is controlled to 0.5 wt% or less, the substance A having a structure of the following general formula (I):

2. The method for preparing a polyurethane resin according to claim 1, wherein the substance A comprises, for example, one or more compounds of the following structural formula:

3. the method of claim 1 or 2, wherein the cycloaliphatic diisocyanate composition is a combination of one or more of dicyclohexylmethane diisocyanate (HMDI), isophorone diisocyanate (IPDI), cyclohexyldimethylene diisocyanate (HXDI), methylcyclohexyl diisocyanate (HTDI), cyclohexyl diisocyanate (CHDI);

preferably, the cycloaliphatic diisocyanate composition is dicyclohexylmethane diisocyanate (HMDI).

4. The process for producing a polyurethane resin according to any one of claims 1 to 3, wherein said substance A is contained in said cycloaliphatic diisocyanate composition in an amount of 0.3 wt.% or less, preferably 0.1 wt.% or less, more preferably 0.05 wt.% or less.

5. The method for producing a polyurethane resin according to any one of claims 1 to 4, wherein the content of said substance A contained in said cycloaliphatic diisocyanate composition is controlled to 0.5 wt.% or less by purifying said cycloaliphatic diisocyanate composition, for example, by rectification separation and/or crystallization separation.

6. The method for producing a polyurethane resin according to any one of claims 1 to 5, wherein the polyol has 2 or more hydroxyl groups and a molecular weight of 400-;

preferably, the polyol has a hydroxyl number of from 10mg KOH/g to 1500mg KOH/g, and a functionality of from 2 to 8 is preferred.

7. The method for producing a polyurethane resin according to any one of claims 1 to 6, wherein the polyurethane resin is produced by a one-step method or a prepolymer method;

the reaction system for preparing the polyurethane resin also comprises a catalyst and a chain extender.

8. The method for preparing the polyurethane resin according to claim 7, wherein the polyurethane resin is prepared by a prepolymer method, comprising the steps of:

9. The method for preparing the polyurethane resin according to claim 8, wherein the polyurethane resin is prepared from the following raw materials in parts by mass:

50-500 parts of the alicyclic diisocyanate composition;

100 parts of the polyol;

50-500 parts of a chain extender;

0.005-1 part of the catalyst.

10. A polyurethane resin, characterized in that it is produced by the production method according to any one of claims 1 to 9, preferably the polyurethane resin is used for the production of a polyurethane elastomer, a polyurethane optical material, a polyurethane coating material or a polyurethane foam, preferably for the production of a polyurethane elastomer.