A blocked polyisocyanate composition and its preparation method and application

Abstract

The present invention provides a blocked polyisocyanate composition and a preparation method and application thereof, wherein the blocked polyisocyanate composition comprises a combination of a blocked polyisocyanate and an aromatic solvent; the mass content of C9-C10 aldehyde compounds in the blocked polyisocyanate composition is ≤50ppm. The present invention effectively solves the problem of color change during storage of blocked polyisocyanates by controlling the content of C9-C10 aldehyde compounds, so that the blocked polyisocyanates have excellent storage stability, stable chromaticity during long-term storage, and no yellowing phenomenon occurs, fully meeting the performance requirements of blocked polyisocyanates in products such as clear paints and light-colored paints.

Description

Technical Field

[0001] The invention belongs to the technical field of isocyanates, and in particular relates to a blocked polyisocyanate composition and a preparation method and application thereof. Background Art

[0002] Blocked polyisocyanates are produced by the reaction of polyisocyanates and blocking agents. The chemical bond formed between the blocking agent and the isocyanate group is relatively weak, and free isocyanate groups can be released under certain conditions. They are widely used in one-component polyurethane coatings and adhesives, and are particularly suitable for automotive coatings and coil coatings.

[0003] There are many types of blocking agents that can be used to prepare blocked polyisocyanates. Currently, the commonly used blocking agents include phenols, alcohols, oximes, β-dicarbonyl compounds, pyrazoles, amides, etc. High-boiling-point aromatic solvents have the characteristics of strong dissolving power, low toxicity, high boiling point, and appropriate volatilization rate, and are often used in the production of blocked polyisocyanates. The general component storage of blocked polyisocyanates has improved stability compared to polyisocyanates, but there is still the problem of yellowing during storage, which has a significant impact on the appearance of the coating, thereby limiting the application of blocked polyisocyanates in clear paints and light-colored paints.

[0004] In order to avoid yellowing of blocked polyisocyanates, researchers have tried to use stabilizers. For example, EP0829500A2 discloses a stable blocked isocyanate, which contains a compound combination as a blocked polyisocyanate stabilizer, in which one component is an amine (HALS) containing at least one 2,2,6,6-tetramethylpiperidin-4-yl, and the other component is a compound containing a hydrazine acyl structure, and also contains other optional stabilizers. US5504178A discloses a single-component coating composition containing an oxime or lactam blocked polyisocyanate, wherein the blocked polyisocyanate is a reaction product of a polyisocyanate and i) 60-99.9 equivalent % of an oxime or lactam blocking agent for isocyanate groups and ii) 0.1-40 equivalent % of hydrazine and / or a compound containing the group H(R)N-NR-CO- that is soluble in polyisocyanates, blocking agents, and solvents. US5631339A discloses yellowing-resistant isocyanate-cured coatings using an anti-yellowing additive based on N-aminoalkyl carbamate for a heat-curable coating composition containing a polyisocyanate crosslinker blocked with a ketoxime.

[0005] In general, among the currently disclosed stabilizers, substances containing hydrazinoyl structures have poor solubility in the reaction system, and the reactive groups are sterically restricted, making it difficult to react completely with the NCO group. The presence of them in a free form will affect the transparency of the product; some stabilizers contain two reactive groups, have a large molecular weight, and have a high viscosity. The amount of solvent needs to be increased during use, which affects the usability and construction properties; in addition, most stabilizers are still in the research and development stage, lack commercial products, and homemade stabilizers have problems such as difficult raw materials, complex processes, and poor economy. Moreover, the existing stabilizers are mainly aimed at the yellowing problem of blocked polyisocyanate / polyurethane coatings during high-temperature baking, and there is no obvious improvement effect on the color stability of blocked polyisocyanates during storage. Therefore, the art is in urgent need of developing blocked polyisocyanates with excellent storage color stability. Summary of the invention

[0006] In view of the deficiencies in the prior art, the object of the present invention is to provide a blocked polyisocyanate composition and a preparation method and application thereof, which solves the problem that the blocked polyisocyanate is prone to discoloration during storage by controlling the content of C9-C10 aldehyde compounds, so that the blocked polyisocyanate composition has low chroma and excellent storage color stability.

[0007] To achieve this object, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a blocked polyisocyanate composition, comprising a combination of a blocked polyisocyanate and an aromatic hydrocarbon solvent; the mass content of C9-C10 aldehyde compounds in the blocked polyisocyanate composition is ≤50ppm.

[0009] The present invention has found in the research process that the content of C9-C10 aldehyde compounds has a significant effect on the chromaticity and storage stability of the blocked polyisocyanate composition; in the blocked polyisocyanate composition provided by the present invention, the mass content of C9-C10 aldehyde compounds is controlled to be ≤50ppm, which can effectively solve the problem of color change during storage of the blocked polyisocyanate composition, making it have excellent storage stability and no yellowing of the color during long-term storage. If the mass content of C9-C10 aldehyde compounds in the system is greater than 50ppm, the color stability of the blocked polyisocyanate composition will deteriorate.

[0010] Preferably, the aromatic hydrocarbon solvent includes C6-C10 aromatic hydrocarbons, for example, C6, C7, C8, C9, and C10 aromatic hydrocarbons.

[0011] Preferably, the aromatic hydrocarbon solvent includes any one of benzene, toluene, xylene, trimethylbenzene, tetramethylbenzene, ethylbenzene, ethyltoluene, ethylethylbenzene, and S100 aromatic hydrocarbon solvent oil, or a combination of at least two thereof.

[0012] The specific types of aromatic solvents listed above in the present invention include all feasible isomers thereof; illustratively, the xylene includes any one of o-xylene, m-xylene, and p-xylene, or a combination of at least two thereof; the trimethylbenzene includes any one of 1,2,3-trimethylbenzene, 1,2,4-trimethylbenzene, and 1,3,5-trimethylbenzene, or a combination of at least two thereof; the tetramethylbenzene includes any one of 1,2,3,5-tetramethylbenzene, 1,2,4,5-tetramethylbenzene, and 1,2,3,4-tetramethylbenzene, or a combination of at least two thereof; the ethyltoluene includes any one of o-ethyltoluene, m-ethyltoluene, and p-ethyltoluene, or a combination of at least two thereof; the ethylethylbenzene includes any one of o-diethylbenzene, m-diethylbenzene, and p-diethylbenzene, or a combination of at least two thereof.

[0013] In the present invention, the C9-C10 aldehyde compounds include C9 aldehyde compounds and / or C10 aldehyde compounds; the C9-C10 aldehyde compounds are impurity components in aromatic hydrocarbon solvents; aromatic hydrocarbon solvents are prone to produce C9 aldehyde compounds and / or C10 aldehyde compounds during production and storage; it is speculated that they may be obtained by oxidation of alkyl groups of C9-C10 aromatic hydrocarbons in aromatic hydrocarbon solvents to aldehyde groups; for example, C9 aldehyde compounds are formed by oxidation of at least one alkyl group (methyl and / or ethyl) in C9 aromatic hydrocarbons to aldehyde groups (formaldehyde and / or acetaldehyde groups); C10 aldehyde compounds are formed by oxidation of at least one alkyl group (methyl and / or ethyl) in C10 aromatic hydrocarbons to aldehyde groups (formaldehyde and / or acetaldehyde groups).

[0014] It should be noted that the C9-C10 aldehyde compounds described in the present invention include three situations: (1) all C9 aldehyde compounds; (2) all C10 aldehyde compounds; (3) a combination of C9 aldehyde compounds and C10 aldehyde compounds.

[0015] In the present invention, "ppm" means parts per million, and 1 ppm means one part per million; the same expressions hereinafter have the same meaning.

[0016] In the present invention, the mass content of C9-C10 aldehyde compounds in the blocked polyisocyanate composition is ≤50ppm, for example, it can be 0, 1ppm, 5ppm, 10ppm, 15ppm, 20ppm, 25ppm, 30ppm, 35ppm, 40ppm, 45ppm or 48ppm, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0017] Preferably, the mass content of C9-C10 aldehyde compounds in the blocked polyisocyanate composition is analyzed and determined by gas chromatography.

[0018] Preferably, the mass percentage of the aromatic hydrocarbon solvent in the blocked polyisocyanate composition is 10-50%, for example, it can be 15%, 20%, 25%, 30%, 35%, 40% or 45%, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0019] As a preferred technical solution of the present invention, by controlling the content of C9-C10 aldehyde compounds, the chromaticity of the blocked polyisocyanate composition stored at 35°C for one year is ≤30 Hazen, more preferably ≤26 Hazen, and can be 15-26 Hazen.

[0020] As a preferred technical solution of the present invention, by controlling the content of C9-C10 aldehyde compounds, the chromaticity change value of the blocked polyisocyanate composition stored at 35°C for 1 year is ≤10Hazen, further preferably ≤5Hazen, as low as 1-5Hazen; the chromaticity change value, that is, the difference between the chromaticity value stored at 35°C for 1 year and the chromaticity value before storage.

[0021] Preferably, the blocked polyisocyanate is obtained by reacting a polyisocyanate with a blocking agent.

[0022] Preferably, the NCO functionality of the polyisocyanate is ≥2.5, for example, it can be 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 10.5, 11, 12 or 13, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range, and it is further preferably 2.5-10.

[0023] Preferably, the mass percentage of NCO groups in the polyisocyanate is 5-40%, for example, it can be 6%, 8%, 10%, 12%, 15%, 18%, 20%, 22%, 25%, 28%, 30%, 32%, 35% or 38%, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0024] In the present invention, the polyisocyanate is obtained by modifying diisocyanate, specifically, it is modified based on diisocyanate by self-polymerization reaction, reaction with polyol, and the like.

[0025] Preferably, the polyisocyanate contains any one or a combination of at least two of isocyanurate group, uretdione group, biuret group, carbamate group, allophanate group, iminooxadiazinedione group, and carbodiimide group, and more preferably contains isocyanurate group.

[0026] Preferably, the diisocyanate comprises an aliphatic diisocyanate and / or an alicyclic diisocyanate, further preferably a C4-C30 (e.g., C5, C6, C7, C8, C9, C10, C12, C14, C15, C16, C18, C20, C22, C25, C28, etc.) aliphatic diisocyanate and / or a C4-C20 (e.g., C5, C6, C7, C8, C9, C10, C12, C14, C15, C16, C18, C20, C22, C25, C28, etc.) alicyclic diisocyanate.

[0027] Preferably, the diisocyanate includes any one or a combination of at least two of 1,4-butane diisocyanate, 1,5-pentane diisocyanate (PDI), 1,6-hexamethylene diisocyanate (HDI), 2,2,4-trimethyl-hexamethylene-1,6-diisocyanate, lysine diisocyanate, isophorone diisocyanate (IPDI), 1,3-bis(isocyanatomethyl)cyclohexane, and 4,4'-dicyclohexylmethane diisocyanate, and more preferably 1,6-hexamethylene diisocyanate (HDI) and / or isophorone diisocyanate (IPDI).

[0028] Preferably, the polyol that reacts with diisocyanate to prepare polyisocyanate includes any one of small molecule polyols, polyester polyols, polyether polyols, acrylic polyols, and polyolefin polyols, or a combination of at least two of them.

[0029] Preferably, the small molecule polyol includes any one of glycerol, trimethylolpropane, and pentaerythritol, or a combination of at least two of them.

[0030] Preferably, the blocking agent includes any one or a combination of at least two of alcohol compounds, phenol compounds, oxime compounds, lactam compounds, β-dicarbonyl compounds, pyrazole compounds, and amine compounds, and oxime compounds and / or lactam compounds are further preferred.

[0031] Preferably, the alcohol compound includes any one of methanol, ethanol, 2-propanol, n-butanol, sec-butanol, 2-ethyl-1-hexanol, 2-methoxyethanol, 2-ethoxyethanol, and 2-butoxyethanol, or a combination of at least two thereof.

[0032] Preferably, the phenolic compound includes any one of phenol, p-cresol, o-cresol, and m-cresol, or a combination of at least two of them.

[0033] Preferably, the oxime compound includes any one of butanone oxime, acetone oxime, formaldehyde oxime, acetaldehyde oxime, and cyclohexanone oxime, or a combination of at least two thereof.

[0034] Preferably, the lactam compound includes any one of ε-caprolactam, δ-valerolactam, and γ-butyrolactam, or a combination of at least two of them.

[0035] Preferably, the β-dicarbonyl compound includes any one of dimethyl malonate, diethyl malonate, ethyl acetoacetate, methyl acetoacetate, di-n-propyl malonate, diisopropyl malonate, di-n-butyl malonate, and diisobutyl malonate, or a combination of at least two thereof.

[0036] Preferably, the pyrazole compound includes 3,5-dimethylpyrazole and / or 3-methylpyrazole.

[0037] Preferably, the amine compound includes any one of diisopropylamine, dipropylamine, and diphenylamine, or a combination of at least two of them.

[0038] Preferably, the blocking agent includes any one of butanone oxime, acetone oxime, and ε-caprolactam, or a combination of at least two of them.

[0039] Preferably, the molar ratio of the blocking agent to the NCO group in the polyisocyanate is (0.9-1.2):1, for example, it can be 0.92:1, 0.95:1, 0.98:1, 1:1, 1.02:1, 1.05:1, 1.08:1, 1.1:1, 1.12:1, 1.15:1 or 1.18:1, and more preferably (0.99-1.05):1.

[0040] In a second aspect, the present invention provides a method for preparing a blocked polyisocyanate composition as described in the first aspect, the preparation method comprising: refining an aromatic hydrocarbon solvent to obtain a refined aromatic hydrocarbon solvent; reacting a polyisocyanate with a blocking agent to generate a blocked polyisocyanate; adding the refined aromatic hydrocarbon solvent at at least one time point before, during, or after the reaction to obtain the blocked polyisocyanate composition.

[0041] In the preparation method provided by the present invention, the aromatic hydrocarbon solvent is refined to obtain a refined aromatic hydrocarbon solvent with a low content of C9-C10 aldehyde compounds.

[0042] Preferably, the mass content of C9-C10 aldehyde compounds in the refined aromatic hydrocarbon solvent is less than 200 ppm, for example, it can be 0, 10 ppm, 30 ppm, 50 ppm, 80 ppm, 100 ppm, 120 ppm, 150 ppm, 180 ppm, and more preferably ≤180 ppm.

[0043] In the present invention, there are many methods for refining the aromatic solvent, including reduction treatment, oxidation treatment, adsorption treatment, rectification treatment, distillation treatment, etc., which can reduce the content of C9-C10 aldehyde compounds in the aromatic solvent, and thus make the mass content of C9-C10 aldehyde compounds in the blocked polyisocyanate composition ≤50ppm.

[0044] Preferably, the refining treatment method includes any one of reduction treatment, oxidation treatment, and adsorption treatment, or a combination of at least two of them. Reduction treatment is further preferred, the purpose of which is to reduce aldehyde impurities to alcohol substances and reduce the content of C9-C10 aldehyde compounds in the aromatic solvent.

[0045] Preferably, the reducing agent of the reduction treatment includes any one of sodium borohydride, lithium aluminum hydride, and hydrogen, or a combination of at least two of them, and sodium borohydride is more preferred.

[0046] Preferably, based on the mass of the aromatic solvent to be treated as 100%, the mass of the reducing agent is 0.01-1%, for example, it can be 0.02%, 0.03%, 0.05%, 0.06%, 0.08%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8% or 0.9%, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0047] Preferably, the temperature of the reduction treatment is 50-80°C, for example, it can be 52°C, 55°C, 58°C, 60°C, 62°C, 65°C, 68°C, 70°C, 72°C, 75°C or 78°C, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0048] Preferably, the reduction treatment time is 3-6 h, for example, it can be 3.25 h, 3.5 h, 3.75 h, 4 h, 4.25 h, 4.5 h, 4.75 h, 5 h, 5.25 h, 5.5 h or 5.75 h, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0049] Preferably, the reduction treatment further includes a filtering step to remove insoluble impurities (such as unconsumed reducing agent) in the solvent system.

[0050] Preferably, the refined aromatic hydrocarbon solvent is added before and / or after the reaction, more preferably before the reaction.

[0051] Preferably, the blocked polyisocyanate composition further comprises other solvents, which can be added at any time before, during or after the reaction.

[0052] Preferably, the other solvents include any one of ester solvents, ketone solvents, and alkane solvents, or a combination of at least two of them.

[0053] Preferably, the ester solvent includes any one of ethyl acetate, butyl acetate, propylene glycol methyl ether acetate, and 3-methoxybutyl acetate, or a combination of at least two thereof.

[0054] Preferably, the ketone solvent includes any one of acetone, butanone, 4-methyl-2-pentanone, and cyclohexanone, or a combination of at least two thereof.

[0055] Preferably, the reaction is carried out in an inert protective atmosphere.

[0056] Preferably, the inert protective atmosphere includes any one of CO2 atmosphere, CO atmosphere, N2 atmosphere, He atmosphere, and Ar atmosphere, or a combination of at least two thereof, and N2 atmosphere is further preferred.

[0057] Preferably, the reaction is carried out under stirring conditions.

[0058] In the present invention, the stirring speed is not particularly limited, as long as the blocking agent and the polyisocyanate in the system are fully mixed, dispersed and contacted to react.

[0059] Preferably, the reaction temperature is 30-150°C, for example, it can be 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C or 140°C, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively enumerates the specific point values ​​included in the range, and 40-120°C is further preferred.

[0060] Preferably, the reaction time is 0.5-10 h, for example, it can be 1 h, 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, 8 h or 9 h, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively enumerates the specific point values ​​included in the range, and 2-5 h is further preferred.

[0061] Preferably, the refined aromatic hydrocarbon solvent is added before the reaction.

[0062] Preferably, the preparation method specifically comprises the following steps:

[0063] (1) using a reducing agent to reduce an aromatic solvent to obtain a refined aromatic solvent; based on the mass of the aromatic solvent to be treated as 100%, the mass of the reducing agent is 0.01-1%; the temperature of the reduction treatment is 50-80° C., and the time is 3-6 hours;

[0064] (2) mixing the polyisocyanate with the refined aromatic solvent obtained in step (1) to obtain a polyisocyanate solution; adding a blocking agent to the polyisocyanate solution, reacting at 30-150° C. for 0.5-10 h in an inert protective atmosphere to obtain the blocked polyisocyanate composition.

[0065] In a third aspect, the present invention provides a use of the blocked polyisocyanate composition as described in the first aspect in a polyurethane coating, a polyurethane adhesive or a polyurethane elastomer.

[0066] Preferably, the blocked polyisocyanate composition is applied to a polyurethane coating, and more preferably a polyurethane one-component baking varnish.

[0067] Preferably, the blocked polyisocyanate composition is used as a curing agent in a polyurethane coating and is prepared with a polyol to form a polyurethane one-component baking varnish, which is particularly suitable for use as an automotive coating or a coil coating.

[0068] Compared with the prior art, the present invention has the following beneficial effects:

[0069] In the blocked polyisocyanate composition provided by the present invention, by controlling the content of C9-C10 aldehyde compounds to ≤50ppm, the problem of color change during storage of the blocked polyisocyanate is effectively solved, so that the storage stability is excellent, and the color does not turn yellow during long-term storage. The chromaticity of the blocked polyisocyanate composition stored at 35°C for 1 year is ≤26 Hazen, and the chromaticity change value stored at 35°C for 1 year is ≤5 Hazen. The chromaticity is stable during long-term storage, which fully meets the performance requirements of the blocked polyisocyanate in products such as clear paint and light-colored paint. DETAILED DESCRIPTION

[0070] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0071] As used herein, the terms "comprises," "including," "having," "containing," or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or apparatus that comprises the listed elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, process, method, article, or apparatus.

[0072] "Optional" or "any one" means that the subsequently described matter or event can or cannot occur, and that the description includes instances where the event occurs and instances where it does not.

[0073] In the following specific embodiments of the present invention, the testing methods of components and performances are as follows:

[0074] 1. Determination of mass content of C9-C10 aldehyde compounds: gas chromatography

[0075] Analytical instrument: Agilent 7890B gas chromatograph;

[0076] Chromatographic column: Agilent 122-5032DB-5 column, 30m×0.25mm×0.25μm;

[0077] Inlet temperature: 250°C;

[0078] Column flow rate: 1.5 mL / min;

[0079] Program temperature rise: 80℃ for 8 min, 20℃ / min to 100℃, hold for 10 min, 35℃ / min to 170℃, hold for 10 min;

[0080] FID detector: 300℃;

[0081] The retention time of C9 aldehyde compounds and C10 aldehyde compounds is 20-23 min, and the contents of C9 aldehyde compounds and C10 aldehyde compounds are calculated according to the area normalization method.

[0082] 2. Chroma

[0083] The Hazen colorimeter was used to test the color.

[0084] In the following specific implementations of the present invention, the sources of the raw materials used are as follows:

[0085] (1) Polyisocyanate

[0086] Wannate HT-100 (HDI trimer), NCO content 22.0%, Wanhua Chemical;

[0087] Wannate IT-100 (IPDI trimer), NCO content 17.0%, Wanhua Chemical.

[0088] (2) Sealing agent

[0089] Butanone oxime, Hubei Lantian New Materials Co., Ltd.;

[0090] ε-Caprolactam, Baling Petrochemical.

[0091] (3) Aromatic solvents

[0092] S100 aromatic solvent oil, C9-C10 aldehyde compound mass content is 450ppm, Jiangsu Hualun Chemical Co., Ltd.

[0093] (4) Reducing agent

[0094] Sodium borohydride, Aladdin reagent.

[0095] Example 1

[0096] A blocked polyisocyanate composition and a preparation method thereof, the preparation method comprising the following steps:

[0097] (1) S100 aromatic solvent oil and sodium borohydride were mixed in a mass ratio of 100:0.15, subjected to reduction treatment at 70° C. for 5 h under stirring conditions, and filtered to obtain a refined aromatic solvent, wherein the mass content of C9-C10 aldehyde compounds was 20 ppm;

[0098] (2) 500 g of polyisocyanate Wannate HT-100 and 243 g of the refined aromatic solvent obtained in step (1) were added to a four-necked bottle under nitrogen protection, 230 g of butanone oxime was added thereto, the reaction temperature was controlled to 60° C., and the reaction was carried out for 3 h to obtain the blocked polyisocyanate composition. The mass content of C9-C10 aldehyde compounds measured by gas chromatography is shown in Table 1.

[0099] Example 2

[0100] A blocked polyisocyanate composition and a preparation method thereof, the preparation method comprising the following steps:

[0101] (1) S100 aromatic solvent oil and sodium borohydride were mixed in a mass ratio of 100:0.1, subjected to reduction treatment at 70° C. for 3 h under stirring conditions, and filtered to obtain a refined aromatic solvent, wherein the mass content of C9-C10 aldehyde compounds was 180 ppm;

[0102] (2) 500 g of polyisocyanate Wannate HT-100 and 243 g of the refined aromatic solvent obtained in step (1) were added to a four-necked bottle, and 230 g of butanone oxime was added thereto under nitrogen protection. The reaction temperature was controlled to 60° C. and the reaction was carried out for 3 h to obtain the blocked polyisocyanate composition, wherein the mass content of the C9-C10 aldehyde compound is as shown in Table 1.

[0103] Comparative Example 1

[0104] A blocked polyisocyanate composition and a preparation method thereof, the preparation method comprising the following steps:

[0105] (1) S100 aromatic solvent oil and sodium borohydride were mixed in a mass ratio of 100:0.1, reduced at 70° C. for 1 h under stirring conditions, and filtered to obtain a refined aromatic solvent, wherein the mass content of C9-C10 aldehyde compounds was 250 ppm;

[0106] (2) 500 g of polyisocyanate Wannate HT-100 and 243 g of the refined aromatic solvent obtained in step (1) were added to a four-necked bottle, and 230 g of butanone oxime was added thereto under nitrogen protection. The reaction temperature was controlled to 60° C. and the reaction was carried out for 3 h to obtain the blocked polyisocyanate composition, wherein the mass content of the C9-C10 aldehyde compound is as shown in Table 1.

[0107] Comparative Example 2

[0108] A blocked polyisocyanate composition and a preparation method thereof, the preparation method comprising the following steps:

[0109] 500 g of polyisocyanate Wannate HT-100 and 243 g of S100 aromatic solvent oil (unrefined, with a C9-C10 aldehyde compound mass content of 450 ppm) were added to a four-necked bottle under nitrogen protection, 230 g of butanone oxime was added thereto, the reaction temperature was controlled to 60° C., and the reaction was carried out for 3 hours to obtain the blocked polyisocyanate composition, wherein the mass content of the C9-C10 aldehyde compound is as shown in Table 1.

[0110] Example 3

[0111] A blocked polyisocyanate composition and a preparation method thereof, the preparation method comprising the following steps:

[0112] (1) S100 aromatic solvent oil and sodium borohydride were mixed in a mass ratio of 100:0.15, reduced at 70° C. for 6 h under stirring conditions, and filtered to obtain a refined aromatic solvent, wherein the mass content of C9-C10 aldehyde compounds was 10 ppm;

[0113] (2) 500 g of polyisocyanate WANNATE IT-100 and 364 g of the refined aromatic solvent obtained in step (1) were added to a four-necked bottle under nitrogen protection, 175 g of butanone oxime was added thereto, the reaction temperature was controlled to 60° C., and the reaction was carried out for 3 h to obtain the blocked polyisocyanate composition, wherein the mass content of the C9-C10 aldehyde compound is as shown in Table 1.

[0114] Example 4

[0115] A blocked polyisocyanate composition and a preparation method thereof, the preparation method comprising the following steps:

[0116] (1) S100 aromatic solvent oil and sodium borohydride were mixed in a mass ratio of 100:0.15, reduced at 60° C. for 4 h under stirring conditions, and filtered to obtain a refined aromatic solvent, wherein the mass content of C9-C10 aldehyde compounds was 100 ppm;

[0117] (2) 500 g of polyisocyanate WANNATE IT-100 and 364 g of the refined aromatic solvent obtained in step (1) were added to a four-necked bottle under nitrogen protection, 175 g of butanone oxime was added thereto, the reaction temperature was controlled to 60° C., and the reaction was carried out for 3 h to obtain the blocked polyisocyanate composition, wherein the mass content of the C9-C10 aldehyde compound is as shown in Table 1.

[0118] Comparative Example 3

[0119] A blocked polyisocyanate composition and a preparation method thereof, the preparation method comprising the following steps:

[0120] (1) S100 aromatic solvent oil and sodium borohydride were mixed in a mass ratio of 100:0.15, reduced at 60° C. for 2 h under stirring conditions, and filtered to obtain a refined aromatic solvent, wherein the mass content of C9-C10 aldehyde compounds was 150 ppm;

[0121] (2) 500 g of polyisocyanate WANNATE IT-100 and 364 g of the refined aromatic solvent obtained in step (1) were added to a four-necked bottle under nitrogen protection, 175 g of butanone oxime was added thereto, the reaction temperature was controlled to 60° C., and the reaction was carried out for 3 h to obtain the blocked polyisocyanate composition, wherein the mass content of the C9-C10 aldehyde compound is as shown in Table 1.

[0122] Comparative Example 4

[0123] A blocked polyisocyanate composition and a preparation method thereof, the preparation method comprising the following steps:

[0124] 500 g of polyisocyanate WANNATE IT-100 and 364 g of S100 aromatic solvent oil (unrefined, with a C9-C10 aldehyde compound mass content of 450 ppm) were added to a four-necked bottle, and nitrogen protection was used. 175 g of butanone oxime was added thereto, and the reaction temperature was controlled to 60° C. The reaction was carried out for 3 hours to obtain the blocked polyisocyanate composition, wherein the mass content of the C9-C10 aldehyde compound is shown in Table 1.

[0125] Example 5

[0126] A blocked polyisocyanate composition and a preparation method thereof, the preparation method comprising the following steps:

[0127] (1) S100 aromatic solvent oil and sodium borohydride were mixed in a mass ratio of 100:0.15, subjected to reduction treatment at 70° C. for 4.5 h under stirring conditions, and filtered to obtain a refined aromatic solvent, wherein the mass content of C9-C10 aldehyde compounds was 30 ppm;

[0128] (2) 500 g of polyisocyanate WANNATE IT-100 and 500 g of the refined aromatic solvent obtained in step (1) were added to a four-necked bottle under nitrogen protection, 250 g of ε-caprolactam was added thereto, and the mixture was heated to 110° C. and reacted for 4 h to obtain the blocked polyisocyanate composition, wherein the mass content of the C9-C10 aldehyde compound is as shown in Table 1.

[0129] Example 6

[0130] A blocked polyisocyanate composition and a preparation method thereof, the preparation method comprising the following steps:

[0131] (1) S100 aromatic solvent oil and sodium borohydride were mixed in a mass ratio of 100:0.15, reduced at 70° C. for 2 h under stirring conditions, and filtered to obtain a refined aromatic solvent, wherein the mass content of C9-C10 aldehyde compounds was 90 ppm;

[0132] (2) 500 g of polyisocyanate WANNATE IT-100 and 500 g of the refined aromatic solvent obtained in step (1) were added to a four-necked bottle under nitrogen protection, 250 g of ε-caprolactam was added thereto, and the mixture was heated to 110° C. and reacted for 4 h to obtain the blocked polyisocyanate composition, wherein the mass content of the C9-C10 aldehyde compound is as shown in Table 1.

[0133] Comparative Example 5

[0134] A blocked polyisocyanate composition and a preparation method thereof, the preparation method comprising the following steps:

[0135] (1) S100 aromatic solvent oil and sodium borohydride were mixed in a mass ratio of 100:0.15, reduced at 60° C. for 2 h under stirring conditions, and filtered to obtain a refined aromatic solvent, wherein the mass content of C9-C10 aldehyde compounds was 150 ppm;

[0136] (2) 500 g of polyisocyanate WANNATE IT-100 and 500 g of the refined aromatic solvent obtained in step (1) were added to a four-necked bottle under nitrogen protection, 250 g of ε-caprolactam was added thereto, and the mixture was heated to 110° C. and reacted for 4 h to obtain the blocked polyisocyanate composition, wherein the mass content of the C9-C10 aldehyde compound is as shown in Table 1.

[0137] Comparative Example 6

[0138] A blocked polyisocyanate composition and a preparation method thereof, the preparation method comprising the following steps:

[0139] 500 g of polyisocyanate WANNATE IT-100 and 500 g of S100 aromatic solvent oil (unrefined, with a C9-C10 aldehyde compound mass content of 450 ppm) were added to a four-necked bottle under nitrogen protection, 250 g of ε-caprolactam was added thereto, and the mixture was heated to 110° C. and reacted for 4 hours to obtain the blocked polyisocyanate composition, wherein the mass content of the C9-C10 aldehyde compound is as shown in Table 1.

[0140] Comparative Example 7

[0141] A blocked polyisocyanate composition and a preparation method thereof, the preparation method comprising the following steps:

[0142] (1) distilling S100 aromatic solvent oil under reduced pressure at 50° C. and 150 Pa to obtain a refined aromatic solvent, wherein the mass content of C9-C10 aldehyde compounds is 350 ppm;

[0143] (2) 500 g of polyisocyanate Wannate HT-100 and 243 g of the refined aromatic solvent obtained in step (1) were added to a four-necked bottle under nitrogen protection, 230 g of butanone oxime was added thereto, the reaction temperature was controlled to 60° C., and the reaction was carried out for 3 h to obtain the blocked polyisocyanate composition. The mass content of C9-C10 aldehyde compounds measured by gas chromatography is shown in Table 1.

[0144] The blocked polyisocyanate compositions obtained in Examples 1-6 and Comparative Examples 1-7 were stored in an environment of 35° C. for 1 year, and then their chromaticity was tested with a BYK digital colorimeter and compared with the chromaticity before storage. The results are shown in Table 1:

[0145] Table 1

[0146]

[0147] Combining the test data of Examples 1-6 and Comparative Examples 1-7 in Table 1, it can be seen that the present invention controls the content of C9-C10 aldehyde compounds in the system to be ≤50ppm, so that the chromaticity of the blocked polyisocyanate composition stored at 35°C for one year is 15-26Hazen, and the chromaticity change value compared with before storage is ≤5Hazen, as low as 1-5Hazen, and the storage color stability is significantly improved.

[0148] The applicant declares that the present invention uses the above-mentioned embodiments to illustrate the blocked polyisocyanate composition of the present invention and its preparation method and application, but the present invention is not limited to the above-mentioned embodiments, that is, it does not mean that the present invention must rely on the above-mentioned embodiments to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of various raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A blocked polyisocyanate composition, characterized in that: The blocked polyisocyanate composition is composed of a blocked polyisocyanate and an aromatic hydrocarbon solvent; the mass content of C9-C10 aldehyde compounds in the blocked polyisocyanate composition is ≤50ppm; The blocked polyisocyanate is obtained by reacting a polyisocyanate and a blocking agent; The blocking agent includes any one of butanone oxime, acetone oxime and ε-caprolactam or a combination of at least two thereof.

2. The blocked polyisocyanate composition according to claim 1, characterized in that: The aromatic hydrocarbon solvent includes C6-C10 aromatic hydrocarbons.

3. The blocked polyisocyanate composition according to claim 2, characterized in that: The aromatic hydrocarbon solvent includes any one of benzene, toluene, xylene, trimethylbenzene, tetramethylbenzene, ethylbenzene, ethyltoluene, ethylethylbenzene, and S100 aromatic hydrocarbon solvent oil, or a combination of at least two of them.

4. The blocked polyisocyanate composition according to claim 1, characterized in that: The mass percentage of the aromatic hydrocarbon solvent in the blocked polyisocyanate composition is 10-50%.

5. The blocked polyisocyanate composition according to claim 1, characterized in that: The NCO functionality of the polyisocyanate is ≥2.

5.

6. The blocked polyisocyanate composition according to claim 5, characterized in that: The NCO functionality of the polyisocyanate is 2.5-10.

7. The blocked polyisocyanate composition according to claim 1, characterized in that: The mass percentage of NCO groups in the polyisocyanate is 5-40%.

8. The blocked polyisocyanate composition according to claim 1, characterized in that: The polyisocyanate contains any one of an isocyanurate group, a uretdione group, a biuret group, a carbamate group, an allophanate group, an iminooxadiazinedione group, and a carbodiimide group, or a combination of at least two of them.

9. The blocked polyisocyanate composition according to claim 1, characterized in that: Preferably, the molar ratio of the blocking agent to the NCO group in the polyisocyanate is (0.9-1.2):

1.

10. A method for preparing a blocked polyisocyanate composition according to any one of claims 1 to 9, characterized in that: The preparation method comprises: Refining the aromatic solvent to obtain a refined aromatic solvent; The polyisocyanate and the blocking agent react to generate a blocked polyisocyanate; the refined aromatic hydrocarbon solvent is added at least one time point before, during, and after the reaction to obtain the blocked polyisocyanate composition.

11. The preparation method according to claim 10, characterized in that: The refining treatment method includes any one of reduction treatment, oxidation treatment, and adsorption treatment, or a combination of at least two of them.

12. The preparation method according to claim 11, characterized in that: The refining treatment method includes reduction treatment.

13. The preparation method according to claim 12, characterized in that: The reducing agent for the reduction treatment includes any one of sodium borohydride, lithium aluminum hydride, and hydrogen, or a combination of at least two of them.

14. The preparation method according to claim 13, characterized in that: The reducing agent of the reduction treatment includes sodium borohydride.

15. The preparation method according to claim 13, characterized in that: Based on the mass of the aromatic hydrocarbon solvent to be treated being 100%, the mass of the reducing agent is 0.01-1%.

16. The preparation method according to claim 12, characterized in that: The temperature of the reduction treatment is 50-80°C.

17. The preparation method according to claim 12, characterized in that: The reduction treatment time is 3-6 hours.

18. The preparation method according to claim 10, characterized in that: The reaction is carried out in an inert protective atmosphere.

19. The preparation method according to claim 10, characterized in that: The reaction temperature is 30-150°C.

20. The preparation method according to claim 19, characterized in that: The reaction temperature is 40-120°C.

21. The preparation method according to claim 10, characterized in that: The reaction time is 0.5-10h.

22. The preparation method according to claim 21, characterized in that: The reaction time is 2-5h.

23. The preparation method according to claim 10, characterized in that: The refined aromatic hydrocarbon solvent is added before the reaction.

24. The preparation method according to claim 10, characterized in that: The preparation method specifically comprises the following steps: (1) using a reducing agent to reduce an aromatic solvent to obtain a refined aromatic solvent; based on the mass of the aromatic solvent to be treated as 100%, the mass of the reducing agent is 0.01-1%; the temperature of the reduction treatment is 50-80° C., and the time is 3-6 hours; (2) mixing the polyisocyanate with the refined aromatic solvent obtained in step (1) to obtain a polyisocyanate solution; adding a blocking agent to the polyisocyanate solution, reacting at 30-150° C. for 0.5-10 h in an inert protective atmosphere to obtain the blocked polyisocyanate composition.

25. Use of the blocked polyisocyanate composition according to any one of claims 1 to 9 in polyurethane coatings, polyurethane adhesives or polyurethane elastomers.

Images