A polyisocyanate composition, process for its preparation and use thereof

Abstract

This invention provides a polyisocyanate composition, its preparation method, and its uses. The polyisocyanate composition provided by this invention, when used in adhesives or coating systems, offers both fast drying speed and good resistance to yellowing. The polyisocyanate composition is obtained by reacting aliphatic and aromatic diisocyanates with a hydroxyl-containing compound. The polyisocyanate composition has urethane groups, urea groups, and optionally isocyanurate groups, and: a) the molar ratio of urea groups to (urethane groups + urea groups + isocyanurate groups) in the polyisocyanate composition is 0.1-0.9; b) during the preparation of the polyisocyanate composition, based on the total molar amount of aliphatic and aromatic diisocyanates consumed in the reaction, the molar ratio of aliphatic diisocyanates consumed in the reaction is 0.3-0.9.

Description

Technical Field

[0001] This invention relates to polyisocyanate compositions containing urea carbamate groups, specifically to a polyisocyanate composition, its preparation method, and its uses. Background Technology

[0002] Polyurethane coatings possess excellent properties such as high hardness, good toughness, strong chemical resistance, and fast drying. They are among the highest-performing and most widely used solvent-based coatings, holding a dominant position in furniture and wood coatings. Polyurethane coatings consist of two components: one is hydroxyl-based substances such as alkyd resins, polyester resins, and acrylic resins; the other key component is a polyurethane prepolymer formed by the preliminary polymerization of isocyanate monomers and alcohols, or by the self-polymerization of isocyanate monomers.

[0003] Polyurethane curing agents, made from isocyanate monomers, inevitably leave some isocyanate monomer residues during the formation of polyurethane prepolymers. This poses potential hygiene problems, and ideally, the less residual isocyanate monomers, the better. With increasingly stringent environmental regulations, the production of polyurethane curing agents must address four key issues: First, reducing the content of free diisocyanate monomers in the curing agent. Currently, thin-film evaporators are commonly used abroad for separation, resulting in monomer content generally below 0.5%. Second, increasing the solids content and NCO content of the curing agent. Third, improving the product's color to achieve a "water-white" finish, avoiding the addition of solvents during curing process, as solvent introduction is not only environmentally unfriendly but also affects the quality of the cured product. Fourth, ensuring good compatibility with hydroxyl components, which is related to the system's polarity and polymer molecular weight distribution.

[0004] Toluene diisocyanate (hereinafter also abbreviated as toluene 2,4-diisocyanate)-based polyisocyanates are commercially used, particularly in surface coatings and adhesives, as crosslinking agents in two-component polyurethane formulations. Their purpose is to achieve chemical crosslinking of the isocyanate reactive component, such as a polyol, and to cure it into a film with high chemical resistance and mechanical strength. For this purpose, a physical mixture of an elastic and highly compatible urethane-based toluene 2,4-diisocyanate adduct and a fast-curing isocyanurate of toluene 2,4-diisocyanate is often used. Because aromatic isocyanates are prone to yellowing, they must be used in combination with aliphatic isocyanates in applications where yellowing is a concern.

[0005] Polyisocyanates based on urethane polymers have been used as crosslinking agents in PU formulations. These polyisocyanates are obtained by converting polyols of different molecular weights with an excess of diisocyanate.

[0006] Polyisocyanates with an isocyanurate structure are obtained through the trimerization of organic diisocyanates. While aromatic isocyanurate polyisocyanates offer rapid drying properties as hardeners for PU coatings, their unfavorable high viscosity, low compatibility, and poor resistance to yellowing limit their use alone, and they require relatively large amounts of organic solvents. On the other hand, aliphatic urethane polyisocyanates exhibit excellent compatibility and elasticity; however, their drying speed is generally too slow, and they typically must be used by blending with less compatible and higher-viscosity aromatic isocyanurate-type polyisocyanates.

[0007] There has long been a desire to prepare polyisocyanates with low viscosity and high functionality to reduce the volatile organic compound (VOC) content of related formulations and provide high curing efficiency. Simultaneously, there is a desire to prepare polyisocyanates with a combination of advantageous properties, including rapid drying, high compatibility, good flexibility, and low viscosity.

[0008] From an occupational health perspective, polyisocyanurates with low monomer content are preferred. To minimize the content of monomeric diisocyanate, it is common practice to convert the monomeric diisocyanate into isocyanurate. However, this disadvantageously results in relatively high molecular weight and therefore high viscosity isocyanurate polyisocyanates. Alternatively, excess monomeric diisocyanate can be removed from the product by physical separation techniques, such as extraction with a suitable solvent and further removal of residual solvent from the crude product. However, the consumption of organic solvents and the complexity of the process increase manufacturing costs. Alternatively, evaporation is widely used to reduce the free monomer content of polyisocyanurates, for example, by using thin-film or short-path evaporators.

[0009] GB994890 discloses the preparation of polyisocyanates containing urea carbamate groups by reacting excess isocyanate with a hydroxyl-containing compound in the presence of a catalyst at a relatively high temperature (125-130°C) for about 20 hours or at a relatively low reaction temperature (45-55°C) for several days, and their use as adhesives. Although for aliphatic polyisocyanates, excess monomeric aliphatic diisocyanates can be removed from the product by subsequent distillation, it is preferred to use only gasoline extraction without distillation to remove excess aromatic isocyanates (such as toluene diisocyanate) from crude aromatic urea carbamate polyisocyanates.

[0010] As disclosed in US 5,672,736 and EP 0 807 623, urea polyisocyanates based on aromatic diisocyanates such as toluene 2,4-diisocyanate are considered unstable, especially when processed using thin-film distillation equipment. The urea polyisocyanates disclosed in US 3,769,318, prepared by reacting an N-substituted carbonate with an organic isocyanate in the presence of an alkylation catalyst, are not further treated by distillation to remove excess isocyanate monomers. Therefore, the high content of monomeric diisocyanates limits the use of such aromatic urea polyisocyanates, for example, in coatings, adhesives, or sealants. Summary of the Invention

[0011] This invention provides a polyisocyanate composition, its preparation method, and its uses. The polyisocyanate composition provided by this invention can be used in adhesive or coating systems, such as in two-component systems, to achieve both fast drying speed and good resistance to yellowing.

[0012] To achieve its objective, the present invention provides the following technical solution:

[0013] This invention provides a polyisocyanate composition obtained by reacting an aliphatic diisocyanate and an aromatic diisocyanate with a hydroxyl-containing compound. The polyisocyanate composition has urethane groups, urea groups, and optionally isocyanurate groups, and:

[0014] a) In the polyisocyanate composition, the molar ratio of urethane groups to (carbamate groups + urethane groups + isocyanurate groups) is 0.1-0.9;

[0015] b) In the preparation of the polyisocyanate composition, based on the total molar amount of aliphatic diisocyanate and aromatic diisocyanate consumed in the reaction, the molar ratio of aliphatic diisocyanate consumed in the reaction is 0.3-0.9.

[0016] Another aspect of the present invention provides a method for preparing the polyisocyanate composition described above, wherein the diisocyanate monomer used to prepare the polyisocyanate composition includes aliphatic diisocyanate and aromatic diisocyanate, and the diisocyanate monomer is divided into two parts: diisocyanate A and diisocyanate B.

[0017] The preparation method includes the following steps:

[0018] 1) Under a protective atmosphere, the diisocyanate A, which contains at least the aliphatic diisocyanate, is reacted with the hydroxyl-containing compound to generate a polyisocyanate containing a carbamate group.

[0019] 2) The polyisocyanate containing urethane groups is reacted with the diisocyanate B containing at least the aromatic diisocyanate in the presence of a catalyst to generate a polyisocyanate containing urea carbamate groups.

[0020] 3) Add a terminator to terminate the reaction; separate the obtained polyisocyanate reaction solution to remove excess diisocyanate;

[0021] 4) Dilute the polyisocyanate composition obtained in step 3) with a solvent to obtain the polyisocyanate composition product.

[0022] In another aspect, the present invention provides the use of the polyisocyanate compositions described above as crosslinking agents in adhesive or coating compositions.

[0023] The technical solution provided by this invention has the following beneficial effects:

[0024] The polyisocyanate composition provided by this invention can be used in adhesive or coating systems, such as in two-component systems, to achieve both fast drying speed and good resistance to yellowing. The polyisocyanate composition provided by this invention has good dilutionability, and a high solids content polyisocyanate composition can be obtained by dilution. Detailed Implementation

[0025] To facilitate understanding of the present invention, the following description, in conjunction with embodiments, will further illustrate the invention. It should be understood that the following embodiments are merely for a better understanding of the invention and do not imply that the invention is limited to these embodiments.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The term "and / or" may be used herein to include any and all combinations of one or more of the associated listed items.

[0027] This invention provides a polyisocyanate composition based on aliphatic and aromatic diisocyanates. Specifically, the polyisocyanate composition is obtained by reacting aliphatic and aromatic diisocyanates with hydroxyl-containing compounds. The polyisocyanate composition has urethane groups, urea groups, and optionally isocyanurate groups, and:

[0028] a) In the polyisocyanate composition, the molar ratio of urethane groups to (carbamate groups + urethane groups + isocyanurate groups) is 0.1-0.9;

[0029] b) In the preparation of the polyisocyanate composition, based on the total molar amount of aliphatic diisocyanate and aromatic diisocyanate consumed in the reaction, the molar ratio of aliphatic diisocyanate consumed in the reaction is 0.3-0.9.

[0030] The polyisocyanate composition provided by this invention can be used in adhesive or coating systems, such as in two-component systems, to achieve both fast drying speed and good resistance to yellowing; moreover, the polyisocyanate composition has good dilutionability, and a high solids content polyisocyanate composition can be obtained by dilution.

[0031] In some examples, the molar ratio of urethane groups to (urethane groups + urethane groups + isocyanurate groups) in the polyisocyanate composition is 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, etc.; and in the preparation of the polyisocyanate composition, based on the total molar amount of aliphatic diisocyanate and aromatic diisocyanate consumed in the reaction, the molar ratio of aliphatic diisocyanate consumed in the reaction is 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, etc.

[0032] In this text, the aliphatic diisocyanate and aromatic diisocyanate consumed during the reaction in the preparation of the polyisocyanate composition refer to the aliphatic diisocyanate and aromatic diisocyanate that participated in the reaction to form the polyisocyanate composition. Based on the total molar amount of aliphatic diisocyanate and aromatic diisocyanate consumed during the reaction, the molar ratio of the amount of aliphatic diisocyanate consumed during the reaction can be determined by NMR spectroscopy analysis of polyisocyanates using 13C-NMR spectroscopy, as detailed in the following description.

[0033] Preferably, the aliphatic diisocyanate is at least one of hexamethylene diisocyanate and 1,5-pentanediisocyanate, more preferably 1,5-pentanediisocyanate; the aromatic diisocyanate is one or more of toluene diisocyanate, preferably the toluene diisocyanate is selected from one or more of toluene 2,4-diisocyanate and toluene 2,6-diisocyanate, more preferably the toluene diisocyanate is toluene 2,4-diisocyanate.

[0034] Furthermore, the content of diisocyanate monomer in the polyisocyanate composition is ≤0.5wt%, preferably ≤0.2wt%, and more preferably ≤0.1wt%.

[0035] Preferably, the isocyanate group content in the polyisocyanate composition is 4-20 wt%, more preferably 10-18 wt%.

[0036] In the text, the urethane group has the following structural formula:

[0037]

[0038] The urea-formate group has the following structural formula:

[0039]

[0040] The isocyanurate group has the following structural formula:

[0041]

[0042] The present invention also provides a method for preparing the polyisocyanate composition described above, wherein the diisocyanate monomers used to prepare the polyisocyanate composition include aliphatic diisocyanates and aromatic diisocyanates, and the diisocyanate monomers are divided into two parts: diisocyanate A and diisocyanate B.

[0043] The preparation method includes the following steps:

[0044] 1) Under a protective atmosphere, the diisocyanate A, which contains at least the aliphatic diisocyanate, is reacted with the hydroxyl-containing compound to generate a polyisocyanate containing a carbamate group.

[0045] 2) The polyisocyanate containing urethane groups is reacted with the diisocyanate B containing at least the aromatic diisocyanate in the presence of a catalyst to generate a polyisocyanate containing urea carbamate groups.

[0046] 3) Add a terminator to deactivate the catalyst, thereby terminating the reaction; separate the obtained polyisocyanate reaction solution, for example, by performing secondary separation through a thin-film evaporator to remove excess unreacted diisocyanate.

[0047] 4) Dilute the polyisocyanate composition obtained in step 3) with a solvent to obtain a polyisocyanate composition product with the target solid content;

[0048] Furthermore, a) in the polyisocyanate composition, the molar ratio of urethane groups to (carbamate groups + urethane groups + isocyanurate groups) is 0.1-0.9; b) in the preparation of the polyisocyanate composition, based on the total molar amount of aliphatic diisocyanates and aromatic diisocyanates consumed during the reaction, the molar ratio of aliphatic diisocyanates consumed during the reaction is 0.3-0.9.

[0049] Polyisocyanates containing urethane groups are obtained by a two-step process involving the conversion of monomeric diisocyanates with OH-functionalized compounds. In the first step, the monomeric diisocyanate is converted with an OH-functionalized compound to form a product containing urethane groups. In the second step, a catalyst is added to the product containing urethane groups to facilitate the conversion of the urethane groups with excess diisocyanate to urethane groups. If the product containing urethane groups contains free isocyanate groups, these isocyanate groups can also be converted to urethane groups.

[0050] In the preparation method of this invention, at least aliphatic diisocyanates containing low-activity isocyanate groups can react with alcohols in step 1) to generate polyisocyanates containing urethane groups. Then, in step 2), under the action of a catalyst, aromatic diisocyanates containing high-activity isocyanate groups are added to generate polyisocyanates containing urea-formate based on aliphatic and aromatic groups. At the same time, the method of this invention can flexibly adjust the ratio between aromatic and aliphatic diisocyanates and flexibly control the content of urea-formate groups in polyisocyanates. The content of urethane groups, urea-formate groups, and isocyanurate groups in polyisocyanates can be arbitrarily designed. For example, a product with a molar ratio of urea-formate groups / (urethane groups + urea-formate groups + isocyanurate groups) of 0.1-0.9 can be easily obtained, resulting in a curing agent with a reasonable and controllable molecular weight distribution and excellent compatibility with alcohols.

[0051] During the preparation process, the molar ratio of urethane groups to (carbamate groups + urethane groups + isocyanurate groups) in the obtained polyisocyanate composition can be adjusted by adjusting the amount of diisocyanate monomers and the degree of reaction. The ratio of the amount of aliphatic diisocyanate consumed in the reaction to the total amount of aliphatic and aromatic diisocyanates consumed in the reaction can be adjusted by adjusting the ratio of aromatic and aliphatic diisocyanates.

[0052] The method of this invention can provide aliphatic and aromatic urea-based polyisocyanates with low free monomer content, exhibiting good dilutionability. High-solids-content polyisocyanate compositions can be obtained through dilution, and these compositions, when used in adhesives or coatings, offer both fast drying speeds and good resistance to yellowing. The polyisocyanate compositions provided by this invention have good compatibility, can be used in two-component systems, and can provide coatings with excellent elasticity. This is a truly green and environmentally friendly product, meeting current industry requirements for green and environmentally friendly practices.

[0053] Preferably, in step 1), the content of the aliphatic diisocyanate in diisocyanate A is not less than 80 wt%, such as 80 wt%, 85 wt%, 90 wt%, 95 wt%, 100 wt%, etc., more preferably not less than 95 wt%. Preferably, the content of 1,5-pentanediisocyanate in diisocyanate A is not less than 80 wt%, more preferably not less than 95 wt%; any deficiency can be made up with other aliphatic or aromatic isocyanates, such as HDI, TDI, etc.

[0054] Preferably, in step 2), the content of aromatic diisocyanate in diisocyanate B is not less than 80 wt%, such as 80 wt%, 85 wt%, 90 wt%, 95 wt%, 100 wt%, etc., and preferably not less than 95 wt%. Preferably, the content of toluene diisocyanate in diisocyanate B is not less than 80 wt%, and preferably not less than 95 wt%; any deficiency can be made up with other aliphatic or aromatic isocyanates, such as HDI, PDI, etc.

[0055] Preferably, in step 1), the molecular weight of the hydroxyl-containing compound is 62-5000; more preferably, the molecular weight is 62-2500; and even more preferably, the molecular weight is 62-1000.

[0056] Suitable hydroxyl-containing compounds for preparing the aliphatic and aromatic urea-based polyisocyanates of the present invention are, for example, any desired monohydric or polyhydric alcohol having a plurality of OH groups, preferably 2-4 OH groups, such as those selected from tetrahydrofurfuryl alcohol, isomeric pentanediol, hexanediol, heptanediol, octanediol, 1,10-decanediol, 1,2-cyclohexanediol, 1,4-cyclohexanediol, 1,4'-cyclohexanediol, 4,4'-(1 One or more of the following: (-methylethylidene)bicyclohexanol, 1,1,1-trimethylolethane, 1,2,6-hexanetriol, 1,1,1-trimethylolpropane, 2,2-bis(hydroxymethyl)-1,3-propanediol, bis(2-hydroxyethyl)hydroquinone, 1,2,4-trihydroxycyclohexane, 1,3,5-trihydroxycyclohexane, 1,3,5-tris(2-hydroxyethyl)isocyanurate, and simple ester alcohols, such as neopentyl glycol hydroxypentanoate.

[0057] Suitable hydroxyl-containing compounds for preparing the aliphatic and aromatic urea-based polyisocyanates of the present invention can also be relatively high molecular weight polyhydroxy compounds known per se, such as polyester, polycarbonate, polyester carbonate, or polyether-type polyhydroxy compounds, more particularly those with a molecular weight of 200-5000 g / mol, preferably 200-2500 g / mol. The average OH functionality of these polyhydroxy compounds is preferably ≥1.5 and ≤5.0, and more preferably ≥1.8 and ≤4.0.

[0058] Suitable polyester polyols as hydroxyl-containing compounds are, for example, those with a molecular weight (which can be calculated from functionality and number of hydroxyl groups) of 200-5000 g / mol, preferably 200-2500 g / mol, and / or a hydroxyl value (OH value) of 16-1400 mg / g KOH, preferably 40-1120 mg / g KOH, which can be prepared in a conventional manner by reacting the polyol (e.g., those with 2-14 carbon atoms as described above) with a substoichiometric polycarboxylic acid, the corresponding carboxylic anhydride, the corresponding lower alcohol polycarboxylic acid ester or lactone.

[0059] Specifically, the ratio of the total molar amount of isocyanate groups in the diisocyanate monomers added in step 1)-2) to the molar amount of hydroxyl groups in the hydroxyl-containing compound is, for example, 6-15:1; the ratio of the total molar amount of isocyanate groups in the diisocyanate monomers added in step 1) to the molar amount of hydroxyl groups in the hydroxyl-containing compound is, for example, 5-10:1.

[0060] In step 2), the catalyst is selected, for example, from one or more compounds containing lead, zinc, tin, zirconium, bismuth, calcium, magnesium and lithium, preferably from one or more compounds containing zinc, zirconium and bismuth; the amount of the catalyst is, for example, 0.005%-0.04% of the total mass of the diisocyanate monomer.

[0061] In step 3), the terminator is selected from one or more of phosphoric acid, phosphate ester, and sulfonic acid, preferably one or more of dibutyl phosphate, diisooctyl phosphate, and p-toluenesulfonic acid; in step 3), the amount of the terminator is, for example, 80%-300% of the mass of the catalyst.

[0062] In step 4), the solid content of the polyisocyanate composition product is, for example, 30-90 wt%, preferably 50-80%, based on the total mass of the polyisocyanate composition product;

[0063] In step 4), the viscosity of the polyisocyanate composition product measured at 25°C is, for example, 100-20000 mPa·s, preferably 200-10000 mPa·s, and more preferably 500-5000 mPa·s.

[0064] In step 4), the solvent used for dilution can be one or more of xylene, ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, propylene glycol methyl ether acetate, and ethylene glycol ethyl ether acetate, preferably one or more of ethyl acetate, n-butyl acetate, and isobutyl acetate.

[0065] In some examples, in step 1), the reaction temperature is 80-110°C, and the reaction is carried out until the target NCO content is reached, for example, until the NCO content is 16-45 wt%; in step 2), the reaction temperature is 90-130°C, and the reaction is carried out until the target NCO content is reached, for example, until the NCO content is 20-45 wt%.

[0066] This invention also provides the use of the aforementioned polyisocyanate compositions as crosslinking agents in adhesive or coating compositions, for example, as crosslinking agents in two-component systems. The polyisocyanate compositions provided by this invention can be used to produce adhesion promoters, adhesives, printing inks, wood coatings, sealants, etc. In particular, using the product obtained by the method according to this invention, the final two-component coating exhibits rapid crosslinking, good chemical and mechanical resistance, and good compatibility with alcohol-based curing agents; it also balances fast drying speed and excellent resistance to yellowing during application.

[0067] The present invention will be further illustrated by the following embodiments, but it should not be construed as the present invention being limited to these embodiments.

[0068] Where specific experimental steps or conditions are not specified in the examples, the corresponding conventional experimental steps or conditions in this technical field can be followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0069] Main raw material sources:

[0070] 1,5-Pentanediisocyanate, purity 99.95%; Wanhua Chemical Group Co., Ltd.

[0071] Toluene 2,4-diisocyanate, purity 99.8%, Wanhua Chemical Group Co., Ltd.

[0072] Zinc isooctanoate, Aladdin Reagents;

[0073] Zirconium isooctanoate, Aladdin Reagents;

[0074] Bismuth isooctanoate, Aladdin Reagents;

[0075] Ethyl acetate, Jin Yimeng Co., Ltd.;

[0076] It is a polyether polyol based on propylene glycol, with a hydroxyl value of 335 mgKOH / gMw = 350 and a functionality of 2. It is manufactured by Wanhua Chemical Group Co., Ltd.

[0077] It is a polyether polyol based on propylene glycol, with a hydroxyl value of 112 mgKOH / g, Mw = 1000, and a functionality of 2. It is manufactured by Wanhua Chemical Group Co., Ltd.

[0078] It is a polyether polyol based on propylene glycol, with a hydroxyl value of 56 mgKOH / g, Mw = 2000, and a functionality of 2. It is manufactured by Wanhua Chemical Group Co., Ltd.

[0079] HS-129 70X, medium hydroxyl type, hydroxyl content 2.12% (70% solids), Sabis Chemicals, Italy;

[0080] Dibutyl phosphate, Aladdin Reagents Co., Ltd.

[0081] p-Toluenesulfonic acid, Aladdin Reagents Co., Ltd.

[0082] Wanhua Chemical Group Co., Ltd.

[0083] Wanhua Chemical Group Co., Ltd.

[0084] Main detection methods:

[0085] NCO content: The NCO content was determined according to the method in GB / T 12009.4-2016;

[0086] Residual monomer content: The residual monomer content in the reaction system was determined by gas chromatography according to the method of GB / T18583-2008;

[0087] Viscosity: Viscosity was tested according to standard GBT 12009.3-2009, using a BrookField DV-IPrime viscometer with an S21 rotor at 25°C;

[0088] Solid content testing was conducted in accordance with standard GB.T1725~2007;

[0089] The contents of urethane, isocyanurate, and carbamate groups in the polyisocyanate composition were determined by NMR spectroscopy analysis of the polyisocyanate using CDCl3 as the solvent and 13C-NMR spectroscopy. Among them:

[0090] The mol% of urethane groups = (molar percentage of urethane groups / (molar percentage of urethane groups + urethane groups + isocyanurate groups)) × 100%;

[0091] The mol% of isocyanurate groups = (molar fraction of isocyanurate groups / (molar fraction of urea groups + carbamate groups + isocyanurate groups)) × 100%;

[0092] Specifically,

[0093] Urea carbamate group mol-% = peak integral @154.0~156.0ppm / (peak integral @154.0~156.0ppm + peak integral @156.5~157.5ppm + peak integral @146~150ppm / 3) × 100%.

[0094] Carbamate group mol-% = peak integral @156.5~157.5ppm / (peak integral @154.0~156.0ppm + peak integral @156.5~157.5ppm + peak integral @146~150ppm / 3) × 100%.

[0095] Isocyanurate group mol-% = (peak integral @146~150ppm / 3) / (peak integral @154.0~156.0ppm + peak integral @156.5~157.5ppm + peak integral @146~150ppm / 3) × 100%.

[0096] In the preparation of isocyanate compositions, the molar ratio of aliphatic diisocyanate consumed during the reaction ("1,5-pentanediisocyanate mol%), based on the total molar amount of aliphatic and aromatic diisocyanates consumed in the reaction, can be determined by NMR spectroscopy analysis of polyisocyanates using CDCl3 as the solvent and 13C-NMR spectroscopy. Wherein:

[0097] 1,5-Pentanediisocyanate mol% = (molar fraction of 1,5-pentanediisocyanate / (1,5-pentanediisocyanate + toluene 2,4-diisocyanate) × 100%).

[0098] Specifically,

[0099] 1,5-Pentanediisocyanate mol% = (peak integral @ 38.0~45.0ppm / 2) / (peak integral @ 16.0~19.0ppm + peak integral @ 38.0~45.0ppm / 2) × 100%.

[0100] Unless otherwise specified, the term "parts" mentioned in the following examples or comparative examples refers to parts by mass.

[0101] Example 1

[0102] In this embodiment, the molar ratio of the total isocyanate groups of all the added diisocyanate monomers to the molar ratio of the hydroxyl groups of the added 1,3-dimethylpropanediol is 9.9:1.

[0103] Under a nitrogen atmosphere, 900 parts of 1,5-pentanediisocyanate were added to a flask equipped with a reflux condenser, a dropping funnel, and a nitrogen inlet, and fitted with a stirrer. The material was heated to 100°C, and 90 parts of 1,3-dimethylpropanediol were added. After reaching an isocyanate (NCO) content of 41.1 wt%, 0.24 parts of bismuth isooctanoate were added to the reaction mixture, followed by 700 parts of toluene-2,4-diisocyanate. The reaction was carried out at 120°C to form urethane groups until the NCO content decreased to 41.2 wt%. Then, 0.48 parts of p-toluenesulfonic acid were added to completely stop the reaction. Excess monomeric diisocyanate was then removed under reduced pressure. The resulting resin was dissolved in ethyl acetate to obtain a polyisocyanate composition P1, which has the following characteristics:

[0104] Isocyanate group content: 14.6 wt%;

[0105] Non-volatile matter content (i.e., solid content): 74.1 wt%;

[0106] Viscosity: 850 mPas;

[0107] Free toluene 2,4-diisocyanate content: 0.25 wt%;

[0108] Free 1,5-pentanediisocyanate content: 0.15 wt%;

[0109] Urea carbamate group mol%: 59.0 mol% (= urea carbamate group / (molar fraction of urea carbamate group + urethane group + isocyanurate group) × 100%);

[0110] Isocyanurate group mol%: 0 mol% (=Isocyanurate group / (molar fraction of urea group + carbamate group + isocyanurate group) × 100%);

[0111] 1,5-Pentanediisocyanate mol%: 61.0 mol% (= 1,5-Pentanediisocyanate / (1,5-Pentanediisocyanate + toluene 2,4-diisocyanate) molar fraction × 100%).

[0112] Example 2

[0113] In this embodiment, the molar ratio of the total isocyanate groups of all the added diisocyanate monomers to the molar ratio of the hydroxyl groups of the added 1,3-dimethylpropanediol is 9.9:1.

[0114] Under a nitrogen atmosphere, 450 parts of 1,5-pentanediisocyanate were added to a flask equipped with a reflux condenser, a dropping funnel, and a nitrogen inlet, and fitted with a stirrer. The material was heated to 95°C, and 45 parts of 1,3-dimethylpropanediol were added. After reaching an isocyanate (NCO) content of 41.0 wt%, 0.08 parts of bismuth isooctanoate were added to the reaction mixture, followed by 350 parts of toluene-2,4-diisocyanate. The reaction was carried out at 110°C to form urethane groups until the NCO content decreased to 42.6 wt%. Then, 0.12 parts of dibutyl phosphate were added to completely stop the reaction. Excess monomeric diisocyanate was then removed under reduced pressure. The resulting resin was dissolved in ethyl acetate to obtain a polyisocyanate composition P2, which has the following characteristics:

[0115] Isocyanate group content: 14.2 wt%;

[0116] Non-volatile matter content: 74.6 wt%;

[0117] Viscosity: 410 mPas;

[0118] Free toluene 2,4-diisocyanate content: 0.06 wt%;

[0119] Free 1,5-pentanediisocyanate content: 0.03 wt%.

[0120] Urea carbamate group mol%: 30.5 mol% (= urea carbamate group / (urea carbamate group + urethane group + isocyanurate group) molar fraction × 100%);

[0121] Isocyanurate group mol%: 0 mol% (=Isocyanurate group / (molar fraction of urea group + carbamate group + isocyanurate group) × 100%);

[0122] 1,5-Pentanediisocyanate mol%: 76.0 mol% (= 1,5-Pentanediisocyanate / (1,5-Pentanediisocyanate + toluene 2,4-diisocyanate) molar fraction × 100%).

[0123] Example 3

[0124] In this embodiment, the molar ratio of the total isocyanate groups of all the added diisocyanate monomers to the molar ratio of the hydroxyl groups of the added 1,3-dimethylpropanediol is 13.3:1.

[0125] Under a nitrogen atmosphere, 1000 parts of 1,5-pentanediisocyanate were added to a flask equipped with a reflux condenser, a dropping funnel, and a nitrogen inlet, and fitted with a stirrer. The material was heated to 95°C, and 75 parts of 1,3-dimethylpropanediol were added. After reaching an isocyanate (NCO) content of 44.3 wt%, 0.36 parts of bismuth isooctanoate were added to the reaction mixture, followed by 800 parts of toluene-2,4-diisocyanate. The reaction was carried out at 110°C to form urethane groups until the NCO content decreased to 42.2 wt%. Then, 0.70 parts of p-toluenesulfonic acid were added to completely stop the reaction. Excess monomeric diisocyanate was then removed under reduced pressure. The resulting resin was dissolved in ethyl acetate to obtain a polyisocyanate composition P3, which has the following characteristics:

[0126] Isocyanate group content: 14.7 wt%;

[0127] Non-volatile matter content: 73.5 wt%;

[0128] Viscosity: 970 mPas;

[0129] Free toluene 2,4-diisocyanate content: 0.08 wt%;

[0130] Free 1,5-pentanediisocyanate content: 0.05 wt%;

[0131] Urea carbamate group mol%: 85.8 mol% (= urethane carbamate group / (molar fraction of urethane carbamate group + urethane carbamate group + isocyanurate carbamate group) × 100%)

[0132] Isocyanurate group mol%: 0 mol% (=Isocyanurate group / (molar fraction of urethane group + carbamate group + isocyanurate group) × 100%)

[0133] 1,5-Pentanediisocyanate mol%: 48.0 mol% (= 1,5-Pentanediisocyanate / (1,5-Pentanediisocyanate + Toluene 2,4-diisocyanate) molar fraction × 100%)

[0134] Example 4

[0135] In this embodiment, the molar ratio of the total isocyanate groups of all the added diisocyanate monomers to the molar ratio of the hydroxyl groups of the added 1,3-dimethylpropanediol is 9.9:1.

[0136] Under a nitrogen atmosphere, 900 parts of 1,5-pentanediisocyanate were added to a flask equipped with a reflux condenser, a dropping funnel, and a nitrogen inlet, and fitted with a stirrer. The material was heated to 95°C, and 90 parts of 1,3-dimethylpropanediol were added. After reaching an isocyanate (NCO) content of 41.0 wt%, 0.19 parts of zirconium isooctanoate were added to the reaction mixture, followed by 700 parts of toluene-2,4-diisocyanate. The reaction was carried out at 105°C to form urethane groups until the NCO content decreased to 42.0 wt%. Then, 0.54 parts of p-toluenesulfonic acid were added to completely stop the reaction. Excess monomeric diisocyanate was then removed under reduced pressure. The resulting resin was dissolved in ethyl acetate to obtain a polyisocyanate composition P4, which has the following characteristics:

[0137] Isocyanate group content: 14.4 wt%

[0138] Non-volatile matter content: 73.7 wt%

[0139] Viscosity: 330 mPas

[0140] Free toluene 2,4-diisocyanate content: 0.05 wt%;

[0141] Free 1,5-pentanediisocyanate content: 0.04 wt%.

[0142] Urea carbamate group mol%: 38.4 mol% (= urethane carbamate group / (molar fraction of urethane carbamate group + urethane carbamate group + isocyanurate carbamate group) × 100%)

[0143] Isocyanurate group mol%: 5.0 mol% (= isocyanurate group / (molar fraction of urethane group + carbamate group + isocyanurate group) × 100%)

[0144] 1,5-Pyrene diisocyanate mol%: 69.0 mol% (= 1,5-Pyrene diisocyanate / (1,5-Pyrene diisocyanate + toluene 2,4-diisocyanate) molar fraction × 100%)

[0145] Example 5

[0146] In this embodiment, the molar ratio of the total isocyanate groups of all the added diisocyanate monomers to the molar ratio of the hydroxyl groups of the added 1,3-dimethylpropanediol is 10.6:1.

[0147] Under a nitrogen atmosphere, 800 parts of 1,5-pentanediisocyanate were added to a flask equipped with a reflux condenser, a dropping funnel, and a nitrogen inlet, and fitted with a stirrer. The material was heated to 95°C, and 75 parts of 1,3-dimethylpropanediol were added. After reaching an isocyanate (NCO) content of 41.8 wt%, 0.15 parts of zinc isooctanoate were added to the reaction mixture, followed by 640 parts of toluene-2,4-diisocyanate. The reaction proceeded at 95°C to form urethane groups until the NCO content decreased to 39.7 wt%. Then, 0.29 parts of p-toluenesulfonic acid were added to completely stop the reaction. Excess monomeric diisocyanate was then removed under reduced pressure. The resulting resin was dissolved in ethyl acetate to obtain a polyisocyanate composition P5, which has the following characteristics:

[0148] Isocyanate group content: 14.8 wt%;

[0149] Non-volatile matter content: 74.2 wt%;

[0150] Viscosity: 1280 mPas;

[0151] Free toluene 2,4-diisocyanate content: 0.18 wt%;

[0152] Free 1,5-pentanediisocyanate content: 0.15 wt%;

[0153] Urea carbamate group mol%: 57.2 mol% (= urea carbamate group / (molar fraction of urea carbamate group + urethane group + isocyanurate group) × 100%)

[0154] Isocyanurate group mol%: 9.8 mol% (= isocyanurate group / (molar fraction of urethane group + carbamate group + isocyanurate group) × 100%)

[0155] 1,5-Pentanediisocyanate mol%: 45.0 mol% (= 1,5-Pentanediisocyanate / (1,5-Pentanediisocyanate + Toluene 2,4-diisocyanate) molar fraction × 100%)

[0156] Example 6

[0157] In this embodiment, the molar ratio of the total isocyanate groups of all the added diisocyanate monomers to the molar ratio of the hydroxyl groups of the added 1,3-dimethylpropanediol is 7.5:1.

[0158] Under a nitrogen atmosphere, 1200 parts of 1,5-pentanediisocyanate were added to a flask equipped with a reflux condenser, a dropping funnel, and a nitrogen inlet, and fitted with a stirrer. The material was heated to 95°C, and 40 parts of 1,3-dimethylpropane and 88 parts of trimethylolpropane were added. After reaching an isocyanate (NCO) content of 39.7 wt%, 0.11 parts of zinc isooctanoate were added to the reaction mixture, followed by 500 parts of toluene-2,4-diisocyanate. The reaction proceeded at 95°C to form urethane groups until the NCO content decreased to 40.9 wt%. Then, 0.20 parts of p-toluenesulfonic acid were added to completely stop the reaction. Excess monomeric diisocyanate was then removed under reduced pressure. The resulting resin was dissolved in ethyl acetate to obtain a polyisocyanate composition P6, which has the following characteristics:

[0159] Isocyanate group content: 15.9 wt%;

[0160] Non-volatile matter content: 72.1 wt%;

[0161] Viscosity: 860 mPas;

[0162] Free toluene 2,4-diisocyanate content: 0.28 wt%;

[0163] Free 1,5-pentanediisocyanate content: 0.12 wt%;

[0164] Urea carbamate group mol%: 13.8 mol% (= urea carbamate group / (molar fraction of urea carbamate group + urethane group + isocyanurate group) × 100%);

[0165] Isocyanurate group mol%: 0 mol% (=Isocyanurate group / (molar fraction of urea group + carbamate group + isocyanurate group) × 100%);

[0166] 1,5-Pentanediisocyanate mol%: 86 mol% (= 1,5-Pentanediisocyanate / (1,5-Pentanediisocyanate + toluene 2,4-diisocyanate) molar fraction × 100%).

[0167] Example 7

[0168] In this embodiment, the ratio of the total molar amount of isocyanate groups of all the added diisocyanate monomers to the molar amount of hydroxyl groups of the added polyether polyol is 9.4:1.

[0169] Under a nitrogen atmosphere, 600 parts of 1,5-pentanediisocyanate were added to a stirrer-equipped flask with a reflux condenser, a dropping funnel, and a nitrogen inlet. The mixture was heated to 100°C, and 200 parts of polyether polyol were added. After achieving an isocyanate (NCO) content of 34.5 wt%, 0.16 parts of bismuth isooctanoate were added to the reaction mixture, followed by 300 parts of toluene-2,4-diisocyanate. The reaction proceeded at 120 °C to form urethane groups until the NCO content decreased to 35.5 wt%. Then, 0.32 parts of p-toluenesulfonic acid were added to completely stop the reaction. Excess monomeric diisocyanate was then removed under reduced pressure. The resulting resin was dissolved in ethyl acetate to obtain a polyisocyanate composition P7, which has the following characteristics:

[0170] Isocyanate group content: 10.5 wt%;

[0171] Non-volatile matter content: 74.5 wt%;

[0172] Viscosity: 500 mPas;

[0173] Free toluene 2,4-diisocyanate content: 0.18 wt%;

[0174] Free 1,5-pentanediisocyanate content: 0.12 wt%;

[0175] Urea carbamate group mol%: 46.8 mol% (= urea carbamate group / (urea carbamate group + urethane group + isocyanurate group) molar fraction × 100%);

[0176] Isocyanurate group mol%: 0 mol% (=Isocyanurate group / (molar fraction of urea group + carbamate group + isocyanurate group) × 100%);

[0177] 1,5-Pentanediisocyanate mol%: 67 mol% (= 1,5-Pentanediisocyanate / (1,5-Pentanediisocyanate + toluene 2,4-diisocyanate) molar fraction × 100%).

[0178] Example 8

[0179] In this embodiment, the ratio of the total molar amount of isocyanate groups of all the added diisocyanate monomers to the molar amount of hydroxyl groups of the added diol is 10:1.

[0180] Under a nitrogen atmosphere, 750 parts of 1,5-pentanediisocyanate were added to a stirrer-equipped flask with a reflux condenser, a dropping funnel, and a nitrogen inlet. The mixture was heated to 100°C, and 800 parts of a diol with a molecular weight of 1000 were added. After achieving an isocyanate (NCO) content of 25.5 wt%, 0.24 parts of bismuth isooctanoate were added to the reaction mixture, followed by 550 parts of toluene-2,4-diisocyanate. The reaction was carried out at 120 °C to form urethane groups until the NCO content decreased to 22.1 wt%. Then, 0.47 parts of p-toluenesulfonic acid were added to completely stop the reaction. Excess monomeric diisocyanate was then removed under reduced pressure. The resulting resin was dissolved in ethyl acetate to obtain a polyisocyanate composition P8, which has the following characteristics:

[0181] Isocyanate group content: 7.4 wt%;

[0182] Non-volatile matter content: 75.8 wt%;

[0183] Viscosity: 220 mPas;

[0184] Free toluene 2,4-diisocyanate content: 0.07%;

[0185] Free glutaryl isocyanate content: 0.02 wt%;

[0186] Urea carbamate group mol%: 75.6 mol% (= urea carbamate group / (urea carbamate group + urethane group + isocyanurate group) molar fraction × 100%);

[0187] Isocyanurate group mol%: 0 mol% (=Isocyanurate group / (molar fraction of urea group + carbamate group + isocyanurate group) × 100%);

[0188] 1,5-Pentanediisocyanate mol%: 55 mol% (= 1,5-Pentanediisocyanate / (1,5-Pentanediisocyanate + toluene 2,4-diisocyanate) molar fraction × 100%).

[0189] Example 9

[0190] In this embodiment, the ratio of the total molar amount of isocyanate groups of all the added diisocyanate monomers to the molar amount of hydroxyl groups of the added diol is 11.8:1.

[0191] Under a nitrogen atmosphere, 550 parts of glutaryl isocyanate were added to a stirrer-equipped flask with a reflux condenser, a dropping funnel, and a nitrogen inlet. The mixture was heated to 100°C, and 1000 parts of a diol with a molecular weight of 2000 were added. After achieving an isocyanate (NCO) content of 16.4 wt%, 0.17 parts of bismuth isooctanoate were added to the reaction mixture, followed by 400 parts of toluene-2,4-diisocyanate. The reaction proceeded at 120 °C to form urethane groups until the NCO content decreased to 20.8 wt%. Then, 0.34 parts of p-toluenesulfonic acid were added to completely stop the reaction. Excess monomeric diisocyanate was then removed under reduced pressure. The resulting resin was dissolved in ethyl acetate to obtain a polyisocyanate composition P9, which has the following characteristics:

[0192] Isocyanate group content: 4.5 wt%;

[0193] Non-volatile matter content: 75.1 wt%;

[0194] Viscosity: 120 mPas;

[0195] Free toluene 2,4-diisocyanate content: 0.06 wt%;

[0196] Free glutaryl isocyanate content: 0.05 wt%;

[0197] Urea carbamate group mol%: 63mol% (=Urea carbamate group / (Urea carbamate group + carbamate group + isocyanurate group) molar fraction × 100%);

[0198] Isocyanurate group mol%: 0 mol% (=Isocyanurate group / (molar fraction of urea group + carbamate group + isocyanurate group) × 100%);

[0199] 1,5-Pentanediisocyanate mol%: 52 mol% (= 1,5-Pentanediisocyanate / (1,5-Pentanediisocyanate + toluene 2,4-diisocyanate) molar fraction × 100%).

[0200] Comparative Example 1 (without glutaryl isocyanate)

[0201] In this comparative example, the molar ratio of the total isocyanate groups of all the diisocyanate monomers added to the molar ratio of the hydroxyl groups of the added 1,3-dimethylpropanediol is 13.3:1.

[0202] Under a nitrogen atmosphere, 950 parts of toluene 2,4-diisocyanate were added to a flask equipped with a reflux condenser, a dropping funnel, and a nitrogen inlet, and fitted with a stirrer. The material was heated to 95°C, and 62 parts of 1,3-dimethylpropanediol were added. After reaching an isocyanate (NCO) content of 39.4 wt%, 0.20 parts of bismuth isooctanoate were added to the reaction mixture, followed by 650 parts of toluene 2,4-diisocyanate. The reaction was carried out at 110°C to form urethane groups until the NCO content decreased to 39.7 wt%. Then, 0.38 parts of p-toluenesulfonic acid were added to completely stop the reaction. Excess monomeric diisocyanate was then removed under reduced pressure. The resulting resin was dissolved in ethyl acetate to obtain a polyisocyanate composition D1, which has the following characteristics:

[0203] Isocyanate group content: 14.3 wt%;

[0204] Non-volatile matter content: 73.8 wt%;

[0205] Viscosity: 900 mPas;

[0206] Free toluene 2,4-diisocyanate content: 0.15 wt%;

[0207] Urea carbamate group mol%: 59.2 mol% (= urea carbamate group / (urea carbamate group + urethane group + isocyanurate group) molar fraction × 100%);

[0208] Isocyanurate group mol%: 0 mol% (=Isocyanurate / (Urea + Carbamate + Isocyanurate group) molar fraction × 100%);

[0209] 1,5-Pentanediisocyanate mol%: 0 mol% (= 1,5-Pentanediisocyanate / (1,5-Pentanediisocyanate + Toluenediisocyanate) molar fraction × 100%).

[0210] Comparative Example 2 (without toluene 2,4-diisocyanate)

[0211] In this comparative example, the molar ratio of the total isocyanate groups of all the diisocyanate monomers added to the molar ratio of the hydroxyl groups of the added 1,3-dimethylpropanediol is 13.3:1.

[0212] Under a nitrogen atmosphere, 950 parts of 1,5-pentanediisocyanate were added to a flask equipped with a reflux condenser, a dropping funnel, and a nitrogen inlet, and fitted with a stirrer. The material was heated to 95°C, and 70 parts of 1,3-dimethylpropanediol were added. After reaching an isocyanate (NCO) content of 44.2 wt%, 0.24 parts of bismuth isooctanoate were added to the reaction mixture, followed by 650 parts of 1,5-pentanediisocyanate. The reaction was carried out at 110°C to form urethane groups until the NCO content decreased to 44.5 wt%. Then, 0.48 parts of p-toluenesulfonic acid were added to completely stop the reaction. Excess monomeric diisocyanate was then removed under reduced pressure. The resulting resin was dissolved in ethyl acetate to obtain a polyisocyanate composition D2, which has the following characteristics:

[0213] Isocyanate group content: 15.2 wt%;

[0214] Non-volatile matter content: 75.1 wt%;

[0215] Viscosity: 270 mPas;

[0216] Free 1,5-pentanediisocyanate content: 0.12 wt%;

[0217] Urea carbamate group mol%: 86.2 mol% (= urea carbamate group / (urea carbamate group + urethane group + isocyanurate group) molar fraction × 100%);

[0218] Isocyanurate group mol%: 0 mol% (=Isocyanurate group / (molar fraction of urea group + carbamate group + isocyanurate group) × 100%);

[0219] 1,5-Pyrene diisocyanate mol%: 100 mol% (= 1,5-Pyrene diisocyanate / (1,5-Pyrene diisocyanate + toluene diisocyanate) molar fraction × 100%).

[0220] Comparative Example 3

[0221] In this comparative example, the molar ratio of the total isocyanate groups of all the diisocyanate monomers added to the molar ratio of the hydroxyl groups of the added 1,3-dimethylpropanediol is 13.3:1.

[0222] This comparative example is based on Example 3, except that the order of addition of 1,5-pentanediisocyanate and toluene-2,4-diisocyanate is reversed.

[0223] Under a nitrogen atmosphere, 800 parts of toluene 2,4-diisocyanate were added to a stirrer-equipped flask with a reflux condenser, a dropping funnel, and a nitrogen inlet. The material was heated to 95°C, and 75 parts of 1,3-dimethylpropanediol were added. After reaching an isocyanate (NCO) content of 36.1 wt%, 0.36 parts of bismuth isooctanoate were added to the reaction mixture, followed by 1000 parts of 1,5-pentanediisocyanate. The reaction was carried out at 110°C to form urethane groups until the NCO content decreased to 42.2 wt%. Then, 0.70 parts of p-toluenesulfonic acid were added to completely stop the reaction. Excess monomeric diisocyanate was then removed under reduced pressure. The resulting resin was dissolved in ethyl acetate to obtain a polyisocyanate composition D3, which has the following characteristics:

[0224] Isocyanate group content: 14.1 wt%;

[0225] Non-volatile matter content: 73.5 wt%;

[0226] Viscosity: 1170 mPas;

[0227] Free toluene 2,4-diisocyanate content: 0.28 wt%.

[0228] Free 1,5-pentanediisocyanate content: 0.09 wt%;

[0229] Urea carbamate group mol%: 84.8 mol% (= urea carbamate group / (molar fraction of urea carbamate group + urethane group + isocyanurate group) × 100%)

[0230] Isocyanurate group mol%: 0 mol% (=Isocyanurate group / (molar fraction of urethane + carbamate group + isocyanurate group) × 100%)

[0231] 1,5-Pentanediisocyanate mol%: 0.1 mol% (= 1,5-Pentanediisocyanate / (1,5-Pentanediisocyanate + Toluene 2,4-diisocyanate) molar fraction × 100%)

[0232] Comparative Example 4

[0233] In this comparative example, the molar ratio of the total isocyanate groups of all the diisocyanate monomers added to the molar ratio of the hydroxyl groups of the added 1,3-dimethylpropanediol is 13.3:1.

[0234] This comparative example is based on Example 3, except that 1,5-pentanediisocyanate and toluene-2,4-diisocyanate are added simultaneously, rather than being added and reacted in two separate steps.

[0235] Under a nitrogen atmosphere, 800 parts of toluene 2,4-diisocyanate and 1000 parts of 1,5-pentanediisocyanate were added to a flask equipped with a reflux condenser, a dropping funnel, and a nitrogen inlet, and fitted with a stirrer. The mixture was heated to 95°C, and 75 parts of 1,3-dimethylpropanediol were added. After reaching an isocyanate (NCO) content of 46.0 wt%, 0.36 parts of bismuth isooctanoate were added to the reaction mixture, and the reaction proceeded at 110°C to form urethane groups until the NCO content decreased to 42.2 wt%. Then, 0.70 parts of p-toluenesulfonic acid were added to completely stop the reaction. Excess monomeric diisocyanate was then removed under reduced pressure. The resulting resin was dissolved in ethyl acetate to obtain a polyisocyanate composition D4, which has the following characteristics:

[0236] Isocyanate group content: 14.2 wt%;

[0237] Non-volatile matter content: 74.1 wt%;

[0238] Viscosity: 1270 mPas;

[0239] Free toluene 2,4-diisocyanate content: 0.24 wt%.

[0240] Free 1,5-pentanediisocyanate content: 0.12 wt%;

[0241] Urea carbamate group mol%: 85.1 mol% (= molar fraction of urea carbamate group / (urea carbamate group / + urethane group / + isocyanurate group) × 100%)

[0242] Isocyanurate group mol%: 0 mol% (=molar fraction of isocyanurate group / / (urethane group / + carbamate group / + isocyanurate group) × 100%)

[0243] 1,5-Pyrene diisocyanate mol%: 0.2 mol% (= 1,5-Pyrene diisocyanate / (1,5-Pyrene diisocyanate + toluene 2,4-diisocyanate) molar fraction × 100%)

[0244] Application testing:

[0245] Conduct the test case as follows:

[0246] The polyisocyanate compositions used in each test example are shown in Table 1. The polyisocyanate compositions used in Test Examples 1-7 are, in order, polyisocyanate compositions P1-P7, and the polyisocyanate compositions used in Test Examples 8-11 are, in order, polyisocyanate compositions D1, D2, D3, and D4. The polyisocyanate composition used in Test Example 12 is... The polyisocyanate composition used in Test Example 13 was and The mixture was obtained at a mass ratio of 2:1.

[0247] Each polyisocyanate composition was blended with HS-129 70X (hydroxyl type in SAPICI, hydroxyl content 2.12%, 70% solids content) as an NCO-reactive component (amounts shown in Table 1), and its drying properties and resistance to yellowing were tested. After further dilution with butyl acetate (amounts shown in Table 1), the molar ratio of isocyanate groups to hydroxyl groups was 1:1, and the solids content of the final formulation was 40% by weight. Detailed ingredient data are shown in Table 1.

[0248] (1) Instrumental method for linear drying time test: The prepared product was mixed evenly, and the prepared paint was applied to a glass strip (150μm). The strip was then placed on a linear drying recorder for testing, with the range set to 24h. Temperature: 25℃; Humidity: 35%RH. The results are summarized in Table 3.

[0249] (2) Yellowing Resistance Test: The prepared materials were mixed evenly and allowed to stand for 15 minutes. The prepared paint was then sprayed onto tinplate (200 μm). The prepared samples were cured at 25℃ and 50% RH for 48 hours before the yellowing resistance test was conducted. Ultraviolet light curing was used for irradiation at a speed of 30 s / pass, with several passes. Gloss and color difference tests were performed. The wavelength parameters are shown in Table 2. The results are summarized in Table 3.

[0250] Table 1 Ingredient Data Table

[0251]

[0252] Table 2. Wavelength parameters of UV curing machine

[0253] band <![CDATA[mJ / CM 2 ]]> <![CDATA[mW / CM 2 ]]> UVA 697 295 UVB 427 220 UVC 183 102 UVV 1161 511

[0254] Table 3. Drying speed and yellowing resistance test results of different two-component systems.

[0255]

[0256] As can be seen from the table, after multiple UV irradiations, all products exhibited a certain degree of yellowing, with a larger ΔE value indicating a higher degree of yellowing. After 10 UV irradiations (30 seconds each), samples using polyisocyanate compositions D1, D3, D4, TL-75E, and TL-75E / TT-350B (2:1) showed significant yellowing and poor UV resistance to yellowing. Test Example 9 exhibited a significantly slower drying speed. In Test Examples 8-13, it was difficult to simultaneously achieve a relatively fast drying speed and good resistance to yellowing. In contrast, in Test Examples 1-7, the polyisocyanate compositions prepared using the embodiments of this invention showed minimal yellowing, excellent UV resistance to yellowing (e.g., ΔE < 3.0), and also achieved a relatively fast drying speed, e.g., T2 < 250 min, T4 ≤ 330 min.

[0257] It is readily understood that the above embodiments are merely illustrative examples for clear explanation and do not imply that the invention is limited thereto. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A polyisocyanate composition obtained by reacting an aliphatic diisocyanate and an aromatic diisocyanate with a hydroxyl-containing compound, the polyisocyanate composition having a carbamate group, a urethane group, and optionally an isocyanurate group, and: a) In the polyisocyanate composition, the molar ratio of urethane groups to (carbamate groups + urethane groups + isocyanurate groups) is 0.1-0.9; b) In the preparation of the polyisocyanate composition, based on the total molar amount of aliphatic diisocyanate and aromatic diisocyanate consumed in the reaction, the molar ratio of aliphatic diisocyanate consumed in the reaction is 0.3-0.

9.

2. The polyisocyanate composition according to claim 1, characterized in that The aliphatic diisocyanate is at least one of hexamethylene diisocyanate and 1,5-pentanediisocyanate, preferably 1,5-pentanediisocyanate. The aromatic diisocyanate is one or more of toluene diisocyanate, preferably selected from one or more of toluene 2,4-diisocyanate and toluene 2,6-diisocyanate, and more preferably toluene 2,4-diisocyanate.

3. The polyisocyanate composition according to claim 1 or 2, characterized in that The content of diisocyanate monomer in the polyisocyanate composition is ≤0.5wt%, preferably ≤0.2wt%, and more preferably ≤0.1wt%.

4. The polyisocyanate composition according to any of claims 1 to 3, characterized in that The isocyanate group content in the polyisocyanate composition is 4-20 wt%, preferably 10-18 wt%.

5. Process for the preparation of the polyisocyanate composition according to any one of claims 1 to 4, characterized in that, The diisocyanate monomers used to prepare the polyisocyanate composition include aliphatic diisocyanates and aromatic diisocyanates, and the diisocyanate monomers are divided into two parts: diisocyanate A and diisocyanate B. The preparation method includes the following steps: 1) Under a protective atmosphere, the diisocyanate A, which contains at least the aliphatic diisocyanate, is reacted with the hydroxyl-containing compound to generate a polyisocyanate containing a carbamate group. 2) The polyisocyanate containing urethane groups is reacted with the diisocyanate B containing at least the aromatic diisocyanate in the presence of a catalyst to generate a polyisocyanate containing urea carbamate groups. 3) Add a terminator to terminate the reaction; separate the obtained polyisocyanate reaction solution to remove excess diisocyanate; 4) Dilute the polyisocyanate composition obtained in step 3) with a solvent to obtain the polyisocyanate composition product.

6. The preparation method according to claim 5, characterized in that, In step 1), the content of the aliphatic diisocyanate in the diisocyanate A is not less than 80 wt%, preferably not less than 95 wt%; Preferably, the content of 1,5-pentanediisocyanate in the diisocyanate A is not less than 80 wt%, and more preferably not less than 95 wt%.

7. The production method according to claim 5 or 6, characterized by, In step 2), the content of the aromatic diisocyanate in the diisocyanate B is not less than 80 wt%, preferably not less than 95 wt%. Preferably, the content of toluene diisocyanate in the diisocyanate B is not less than 80 wt%, and more preferably not less than 95 wt%.

8. The method of any one of claims 5-7, wherein, In step 1), the molecular weight of the hydroxyl-containing compound is 62-5000.

9. The method of any one of claims 5-8, wherein, In step 2), the catalyst is selected from one or more compounds containing lead, zinc, tin, zirconium, bismuth, calcium, magnesium and lithium, preferably one or more compounds containing zinc, zirconium and bismuth; And / or, in step 3), the terminating agent is selected from one or more of phosphoric acid, phosphate ester, and sulfonic acid, preferably one or more of dibutyl phosphate, diisooctyl phosphate, and p-toluenesulfonic acid; And / or, in step 3), the amount of the terminating agent is 80%-300% of the mass of the catalyst; And / or, in step 4), the solid content of the polyisocyanate composition product is 30-90 wt%, preferably 50-80%, based on the total mass of the polyisocyanate composition product; And / or, in step 4), the viscosity of the polyisocyanate composition product measured at 25°C is 100-20000 mPa·s, preferably 200-10000 mPa·s, more preferably 500-5000 mPa·s; And / or, in step 4), the solvent is one or more of xylene, ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, propylene glycol methyl ether acetate, and ethylene glycol ethyl ether acetate, preferably one or more of ethyl acetate, n-butyl acetate, and isobutyl acetate.

10. Use of the polyisocyanate composition according to any one of claims 1-9 as a crosslinking agent in adhesive or coating compositions.

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