Dual-curable polyurea-based formate acrylate composition

Abstract

The invention provides a dual-curable low-viscosity, low-dissociation and stable-storage polyallophanate acrylate composition which is provided by the invention. The composition is a polyisocyanate composition which is prepared from aliphatic diisocyanate or alicyclic diisocyanate and one or more acrylic acid hydroxyl esters. The integral area of the peak of the component with the weight-average molecular weight of 264 + / -80 in the composition accounts for 0.1-10% of the overall peak area of the GPC, the peak area of the component with the weight-average molecular weight of 480 + / -80 accounts for 20-70% of the overall peak area of the GPC, and the viscosity of the polyisocyanate composition does not exceed 3000 mPa.s. The isocyanate composition has good storage stability, and based on the quality of a polyisocyanate product, the monomer content is increased by less than or equal to 0.15% after the isocyanate composition is stored at 50 DEG C for 30 days.

Description

Technical Field

[0001] The present invention belongs to the field of polyisocyanates, and particularly relates to a polyurea urethane acrylate composition that can be doubly cured. Background Art

[0002] In recent years, with people's increasing attention to energy utilization and environmental protection, the country has imposed stricter restrictions on the emission of volatile organic compounds (VOCs) from traditional solvent-based coatings. Therefore, one of the main directions of the current development of the coating industry is to develop environmentally friendly coatings with low pollution. UV oligomers are important components that determine the properties of UV coatings, and are mainly divided into epoxy acrylate, polyurethane acrylate, polyester / polyether acrylate, and unsaturated polyester. Polyurethane acrylate not only retains various excellent properties such as good abrasion resistance, good flexibility, high tear strength, and good low-temperature resistance, but also has the properties of good light and color retention and good water and chemical resistance of acrylic resin. Since hydrogen bonds are easily formed between the molecules of urethane acrylate compounds, it leads to high viscosity and turbidity of the system, which is not conducive to coating spraying. Therefore, it is necessary to derivatize it into a urethane compound to achieve the purpose of reducing the system viscosity. Since photo-curing coatings require photo-radiation initiation during use, but in actual spraying objects, there are often areas such as pores or other three-dimensional shadow surfaces that cannot be irradiated by light. Therefore, it is necessary to develop a pre-polymer that can be doubly cured by light and heat.

[0003] Currently, urethane acrylate compounds are synthesized from polyisocyanate monomers, alcohols containing unsaturated double bonds, and ester compounds; they can also be synthesized from polyisocyanate derivatives rather than from urethane and polyisocyanate monomers:

[0004] For example: CN1310994C discloses a method for synthesizing urethane using oxadiazinetrione as a raw material; CN1746244B and CN1746245B disclose methods for synthesizing urethane using uretdione as a raw material under the catalysis of zinc salts and phosphonium salts; the raw materials of the above methods are difficult to obtain at a high level, and only urethane products rich in by-products are obtained. Moreover, when the products are actually stored at 50 °C, it is found that the content of free monomers increases rapidly and the storage stability is poor;

[0005] CN1831026A, CN100516106C, CN101050263B, and CN101372529B disclose methods for synthesizing urethane products using poly- or mono-isocyanate, acrylic hydroxy ester, polyether or polyester polyol as raw materials, but the NCO content of the products is low and the viscosity is high, and the requirements for double curing cannot be achieved.

[0006] The main disadvantages of the urethanoacrylate compounds prepared by the existing processes are high viscosity, and the cracking of some compounds during long-term storage releases isocyanates, resulting in a high monomer content, which affects the downstream construction performance and the health of operating workers. Summary of the Invention

[0007] The object of the present invention is to provide a polyisocyanate composition, the composition of which has low viscosity, can be doubly cured, and the content of free monomers increases less during storage at 50 °C, which can meet the actual application requirements of downstream and the needs of occupational health and safety.

[0008] In order to achieve the above object of the invention, the polyisocyanate composition provided by the present invention adopts the following technical scheme:

[0009] A polyisocyanate composition, which is a polyisocyanate composition obtained by reacting an aliphatic diisocyanate and / or an alicyclic diisocyanate with a hydroxy acrylate, and the composition has the following characteristics:

[0010] a. The integral area of the component peak with a weight-average molecular weight of 264 ± 80 accounts for 0.1-10% of the total peak area, preferably 0.5-8%, and more preferably 1-6%;

[0011] b. The integral area of the peak of the component with a weight-average molecular weight of 480 ± 80 accounts for 20-70% of the total peak area, preferably 30-60%;

[0012] Among them, the peaks of the above components with different molecular weights are obtained by characterization using gel chromatography technology (GPC).

[0013] In the present invention, the polyisocyanate composition has a viscosity less than or equal to 3000 mPa·s, preferably less than or equal to 2000 mPa·s.

[0014] In the present invention, the aliphatic diisocyanate and / or alicyclic diisocyanate is an organic diisocyanate having 4-20 carbon atoms in the carbon skeleton in addition to the NCO group. Preferably, the isocyanate is selected from one or more of hexamethylene diisocyanate (HDI), pentamethylene diisocyanate (PDI), isophorone diisocyanate (IPDI), cyclohexyl dimethylene diisocyanate (HMDI), dicyclohexylmethane diisocyanate (HXDI), norbornane dimethylene diisocyanate (NBDI), cyclohexyl diisocyanate (CHDI), and 2,4,4-trimethylhexane diisocyanate (TMHDI), and more preferably hexamethylene diisocyanate and pentamethylene diisocyanate.

[0015] In the present invention, the hydroxy acrylate is prepared from acrylic acid or methacrylic acid and a diol having 2 to 10 carbon atoms, and preferably one or more of hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, and hydroxypropyl methacrylate.

[0016] In the present invention, the viscosity of the composition is low, less than 3000 cP / 25 °C, and can be cured by both heat and light. When stored at 50 °C for 1 month, the content of free isocyanate monomer increases by ≤0.15 wt%, based on the total mass of the polyisocyanate composition.

[0017] Another object of the present invention is to provide a method for preparing a polyisocyanate composition.

[0018] A method for preparing the above polyisocyanate composition, and the method is Preparation Method A or Preparation Method B.

[0019] In the present invention, Preparation Method A includes the following steps:

[0020] S1-1: After adding an inhibitor to the excessive diisocyanate, reacting with the hydroxy acrylate under heating conditions. After the complete conversion of the hydroxy acrylate, a prepolymerization reaction solution is obtained;

[0021] S1-2: Optionally adding a catalyst to the prepolymerization reaction solution. After the reaction reaches the set conversion rate, adding a terminator to terminate the reaction;

[0022] S1-3: Removing the unreacted diisocyanate monomer to obtain a polyisocyanate composition product;

[0023] Preparation Method B includes the following steps:

[0024] S2-1’: Preparing a polyisocyanate composition according to Preparation Method A;

[0025] S2-1: Reacting the diisocyanate with the hydroxy acrylate to obtain a prepolymerization reaction solution, and removing the unreacted organic isocyanate monomer;

[0026] S2-2: Blending the product of S2-1’ with the product of S2-1 to obtain a polyisocyanate composition product.

[0027] In the present invention, in S1-1, the molar ratio of the diisocyanate to the hydroxy acrylate is (1 to 10):1, preferably (2 to 8):1, and more preferably (3 to 6):1;

[0028] The reaction temperature is 50 to 100 °C, preferably 60 to 80 °C; the reaction time is 0.5 to 4 h, preferably 1 to 2 h;

[0029] In the present invention, the polymerization inhibitor in S1-1 is a hydroquinone, 2,6-di-tert-butylphenol, nitrosamine, phenothiazine and its derivatives or phospholipids, preferably phenothiazine;

[0030] The dosage of the polymerization inhibitor is 0.001-2 wt% of the mass of the diisocyanate, preferably 0.005-1.0 wt%;

[0031] In the present invention, in S1-2, the catalyst is selected from one or more of organotin compounds, organozinc compounds, alkali metal salts, tertiary amines and salt compounds; among them, the organotin compounds are selected from dibutyltin dilaurate and stannous octoate; the organozinc compounds are selected from zinc isooctanoate, zinc octoate and zinc acetylacetonate; the alkali metal salt is sodium acetate; the tertiary amines and salt compounds are selected from 2-ethylhexanoate of N,N,N-trimethyl-N-(2-hydroxypropyl)ammonium, N,N,N-trimethyl-N-(2-hydroxypropyl)ammonium hydroxide, and N,N,N-trimethyl-N-(2-hydroxypropyl)ammonium fluoride, and further preferably zinc isooctanoate and 2-ethylhexanoate of N,N,N-trimethyl-N-(2-hydroxypropyl)ammonium; the dosage of the catalyst is 100-2000 ppm of the mass of the diisocyanate, preferably 200-1000 ppm;

[0032] In the present invention, the reaction temperature of S1-2 is 80-140 °C, preferably 100-120 °C; the reaction time is 0.5-4 h, preferably 1-3 h.

[0033] In the present invention, in S2-1, the molar ratio of the diisocyanate to the hydroxy acrylate is (1-5):1, preferably (1.2-3):1; the reaction temperature is 50-80 °C, preferably 60-70 °C; the reaction time is 0.5-4 h, preferably 1-2 h;

[0034] In the present invention, in S2-2, the blending mass ratio of the product of S2-1 to the product of S2-1' is 0.01-10%, preferably 3-5%.

[0035] When the inventor analyzed the component structure of the reaction solution of the polyisocyanate composition by a high performance gel chromatography instrument, it was surprisingly found that the peaks of the components with a weight average molecular weight of 480±80 and the peaks of the components with a weight average molecular weight of 264±80 would significantly affect the product viscosity and storage stability;

[0036] Among them, the content of the relevant component peak with a weight average molecular weight of 264±80 is mainly determined by the prepolymerization process. When the integral area of the component peak with a weight average molecular weight of 264±80 accounts for 0.1-10% of the overall peak area, the storage stability of the product can be significantly improved. Its content can be controlled by controlling the prepolymerization reaction process, or by separating the prepolymerization reaction solution and adding the separated product to the product;

[0037] When the ratio of the peak area of the component peak with a weight-average molecular weight of 264 ± 80 to the overall peak area is less than 0.1%, the increase in monomer content during storage at 50°C cannot be inhibited. When the ratio is greater than 10%, white flocculants will appear during storage, affecting the application of downstream products.

[0038] In the polyisocyanate composition prepared in the present invention, a peak with a weight-average molecular weight of 480 ± 80 appears, corresponding to a large amount of urethane structure. The content of this structure will affect the viscosity of the product. To prepare a high content of urethane structure, zinc isooctanoate and 2-ethylhexanoate catalyst of N,N,N-trimethyl-N-(2-hydroxypropyl) ammonium are preferably selected. The dosage of the catalyst is usually 100 - 2000 ppm, preferably 200 - 1000 ppm, based on the starting diisocyanate used.

[0039] In the method of the present invention, the area of the peak of the component with a weight-average molecular weight of 480 ± 80 can be adjusted by adjusting the conversion rate in the system. When the ratio of the remaining mass of isocyanate in the system to the total mass of isocyanate monomers in the system reaches 10% - 80%, preferably 20% - 50%, a terminator is added to terminate the reaction. The terminators used are dimethyl sulfate, methyl p-toluenesulfonate, phosphate ester, acyl chloride, sulfur, peroxide, etc. The amount of catalyst poison required to terminate the reaction depends on the dosage of the catalyst in the system, and the dosage of the terminator is 60 - 120% of the molar amount of the catalyst used in the reaction.

[0040] After the reaction is completed, for the unreacted monomers, suitable separation methods include one or more of flash evaporator, falling film evaporator, thin film evaporator, and short-path evaporator to remove the isocyanate monomers from the system. In the polyisocyanate composition, the content of unreacted isocyanate monomers is preferably below 0.5 wt%, more preferably below 0.3 wt%. Since the polyisocyanate derived from acrylic hydroxy ester is prone to gel polymerization at high temperatures, to reduce double bond polymerization, the separation temperature needs to be controlled at 120 - 150°C, and the residence time of the material at high temperature ≤ 20 min, preferably ≤ 10 min.

[0041] The unreacted diisocyanate obtained by separation can be returned to the reaction kettle to participate in the reaction, or can participate in the reaction after distillation or rectification treatment. In the method of the present invention, it is preferably directly returned to the reaction kettle to participate in the reaction without distillation or rectification treatment.

[0042] The polyisocyanate product prepared by the method of the present invention can be used to prepare one-component and multi-component polyurethane coatings or adhesives, and can be used together with di- or poly-isocyanate products prepared by the prior art, such as mixtures of di- or poly-isocyanates containing biuret, carbamate, urethane, isocyanurate, and iminooxadiazinedione.

[0043] The present invention also relates to polyurethane coatings, polyurethane adhesives and other related products prepared by the method of the present invention and containing polyisocyanates.

[0044] Compared with the prior art, the present invention has the following positive effects:

[0045] Polyisocyanates containing radiation-curable groups generally have a relatively high viscosity and tend to decompose into free isocyanate monomers during storage. By controlling the content of the integral area of the peaks of the components with a weight-average molecular weight of 480±80 and a weight-average molecular weight of 264±80 in the polyisocyanate, the present invention obtains a product that can be cured by both light and heat and has a low viscosity, and greatly improves the storage stability of the product at 50°C, so that the content of free isocyanate monomers in the obtained polyisocyanate product increases by ≤0.15 wt% (calculated based on the polyisocyanate product) after storage at 50°C for 30 days, showing good storage stability. Description of the Drawings

[0046] Figure 1 It is the gel chromatogram of Example 1, where peak 6 is the peak with a weight-average molecular weight of 480±80, and peak 7 is the peak with a weight-average molecular weight of 264±80. Detailed Embodiments

[0047] The following examples will further illustrate the method provided by the present invention. However, the present invention is not limited to the listed examples and should also include any other known changes within the scope of the claims of the present invention. The specific applications of the present invention are not limited to those described in the examples. Simple changes made to the present invention by those familiar with the art using the concept of the present invention are within the scope of protection of the present invention.

[0048] The following test methods are used in the examples of the present invention:

[0049] (1) The determination of the area of the component peak with a weight-average molecular weight of 480±80 and the area of the peak with a weight-average molecular weight of 264±80 is carried out using gel chromatography technology (LC-20AD / RID-10A, the chromatographic column is MZ-Gel SD plus10E3A, 5μm (8.0*300mm), MZ-Gel SDplus 500A 5μm (8.0*300mm), MZ-Gel SDplus 100A5μm (8.0*300mm) in series, Shimadzu, using polystyrene as the standard sample, the mobile phase: tetrahydrofuran; the flow rate: 1.0 mL / min; the analysis time: 40 min, the chromatographic column temperature: 35°C), and is determined using a differential detector. For the quantitative determination of isocyanate raw materials, the areas of polymers and monomers in the system are determined by the area normalization method. The reaction conversion rate (%) = 1 - S(monomer peak area) / S(sum of the areas of all component peaks) * 100%.

[0050] (2) High performance liquid chromatography, equipped with an ultraviolet detector or a diode array detector. The recommended instrument model is Shimadzu 20AT. Chromatographic column: Waters XSelect T3 (4.6 * 250mm, 5um). Mobile phase A is water, mobile phase B is methanol. Flow rate: 1ml / min. Analysis time: 50min. Column temperature: 40°C. Analyze using a 258nm ultraviolet detector.

[0051] Gradient elution conditions:

[0052]

[0053] Sample preparation: Take 500mg of the sample and place it in a 10ml volumetric flask. Add the derivatization solution (100g of benzyl alcohol dissolved in a 1000ml volumetric flask, add 3g of dibutyltin dilaurate and dilute to 1000ml with dichloromethane) to the scale line, shake well and seal. Then place it in an oven at 50°C for 3 hours. After cooling, perform sample analysis.

[0054] (3) Viscosity measurement. The dynamic mechanical viscosity is measured using a BrookField DV-IPrime viscometer with an S21 rotor at 25°C.

[0055] In the following examples, the raw material information is as follows:

[0056] Hexamethylene diisocyanate (abbreviation: HDI): Wanhua Chemical, purity > 99%;

[0057] Pentamethylene diisocyanate (abbreviation: PDI): Wanhua Chemical, purity > 99%;

[0058] 2-Hydroxyethyl acrylate (HEA): Aladdin Reagent, purity > 96%;

[0059] 2-Hydroxyethyl methacrylate (HEMA): Aladdin Reagent, purity > 98%;

[0060] Diisooctyl phosphate: Aladdin Reagent, purity > 98.5%;

[0061] Zinc isooctanoate: Sigma Reagent, purity ≥ 95%;

[0062] 2-Ethylhexanoate of N,N,N-trimethyl-N-(2-hydroxypropyl) ammonium: Sigma Reagent, purity ≥ 95%;

[0063] Phenothiazine: Aladdin Reagent, purity > 99.5%;

[0064] Dibutyltin dilaurate: Aladdin Reagent, purity > 95%;

[0065] Isooctanol: Aladdin reagent, purity > 95%;

[0066] Tetramethylammonium hydroxide: Aladdin reagent, purity > 95%;

[0067] In the following examples and comparative examples, without special instructions, during the process from before the reaction to the addition of the catalyst and throughout the reaction, the reaction solution was kept under dry nitrogen protection. Unless otherwise stated, all percentages are mass percentages, and the pressures are absolute pressures.

[0068] Example 1

[0069] Preparation method A was adopted.

[0070] S1-1: 1000 g of hexamethylene diisocyanate with a mass M was stirred at 60 °C, 1 g of phenothiazine was added, and then 232 g of hydroxyethyl acrylate was added, and the reaction was carried out for 2 hours;

[0071] S1-2: The temperature was raised to 100 °C, 1.0 g of 2-ethylhexanoate of N,N,N-trimethyl-N-(2-hydroxypropyl)ammonium was added, and the proportion of the remaining mass M1 of HDI in the total mass M of the added HDI in the reaction system was quantitatively monitored by gel chromatography; when the remaining mass M1 of HDI in the system accounted for 50% of the total mass M of the added HDI, the reaction was terminated by adding diisooctyl phosphate (molar ratio 1:1 with 2-ethylhexanoate of N,N,N-trimethyl-N-(2-hydroxypropyl)ammonium);

[0072] S1-3: Two-stage thin-film evaporator distillation was carried out at a temperature of 140 °C and a pressure of 0.3 mbar to remove the unreacted HDI in the reaction system, and a polyisocyanate composition 1 containing radiation-curable urethane groups was obtained.

[0073] Example 2

[0074] Preparation method B was adopted.

[0075] S2-1’: Weigh 1000 g of hexamethylene diisocyanate with a mass M. Under stirring at 60 °C, add 1 g of phenothiazine, then add 232 g of hydroxyethyl acrylate and react for 2 hours. Raise the temperature to 100 °C, add 1.0 g of 2-ethylhexanoate of N,N,N-trimethyl-N-(2-hydroxypropyl)ammonium, and quantitatively monitor the proportion of the remaining mass M1 of HDI in the reaction system to the total mass M of the added HDI by gel chromatography. When the remaining mass M1 of HDI in the system accounts for 50% of the total mass M of the added HDI, add diisooctyl phosphate (molar ratio 1:1 with 2-ethylhexanoate of N,N,N-trimethyl-N-(2-hydroxypropyl)ammonium) to terminate the reaction. Carry out two-stage thin-film evaporator distillation at a temperature of 140 °C and a pressure of 0.3 mbar to remove the unreacted HDI in the reaction system, and obtain a polyisocyanate composition containing radiation-curable urethane groups;

[0076] S2-1: 2000 g of hexamethylene diisocyanate with a mass M. Under stirring at 70 °C, add 0.2 g of phenothiazine, then add 232 g of hydroxyethyl acrylate and react for 2 hours to obtain a prepolymerization reaction solution. Carry out two-stage thin-film evaporator distillation on the reaction solution at a temperature of 140 °C and a pressure of 0.3 mbar to remove the unreacted HDI in the reaction system, and obtain a polyisocyanate composition with a monomer content of less than 0.5%.

[0077] S2-2: Blend the polyisocyanate composition of S2-1 into the polyisocyanate composition containing urethane groups of S2-1’, with the mixing mass ratio of the former to the latter being 5:95, to obtain polyisocyanate composition 2.

[0078] Example 3

[0079] 1000 g of hexamethylene diisocyanate with a mass M. Under stirring at 60 °C, add 1 g of phenothiazine, then add 116 g of hydroxyethyl acrylate and react for 2 hours. Raise the temperature to 120 °C, add 0.3 g of zinc isooctanoate, and quantitatively monitor the proportion of the remaining mass M1 of HDI in the reaction system to the total mass M of the added HDI by gel chromatography. When the remaining mass M1 of HDI in the system accounts for 40% of the total mass M of the added HDI, add diisooctyl phosphate (molar ratio 1.2:1 with zinc isooctanoate) to terminate the reaction. Carry out two-stage thin-film evaporator distillation at a temperature of 140 °C and a pressure of 0.3 mbar to remove the unreacted HDI in the reaction system, and obtain a polyisocyanate composition 3 containing radiation-curable urethane groups.

[0080] Example 4

[0081] The procedure is the same as in Example 1, except that when the remaining mass M1 of HDI in the system accounts for 30% of the total mass M of the added HDI, diisooctyl phosphate (molar ratio to 2-ethylhexanoate of N,N,N-trimethyl-N-(2-hydroxypropyl)ammonium is 0.8:1) is added to terminate the reaction, and after separation, a polyisocyanate composition 4 containing radiation-curable urethane groups is obtained.

[0082] Example 5

[0083] The procedure is the same as in Example 1, except that 232 g of hydroxyethyl acrylate added to the system is replaced by adding 262 g of hydroxyethyl methacrylate, and the reaction solution is finally distilled in a two-stage thin-film evaporator at a temperature of 140 °C and a pressure of 0.3 mbar to remove the unreacted HDI in the reaction system, and a polyisocyanate composition 5 containing radiation-curable urethane groups is obtained.

[0084] Example 6

[0085] The procedure is the same as in Example 1, except that 1000 g of HDI in the system is replaced by 924 g of PDI, and the reaction solution is finally distilled in a two-stage thin-film evaporator at a temperature of 140 °C and a pressure of 0.3 mbar to remove the unreacted HDI in the reaction system, and a polyisocyanate composition 6 containing radiation-curable urethane groups is obtained.

[0086] Comparative Example 1

[0087] Prepare a polyisocyanate substantially free of components with a weight average molecular weight of 264 ± 80.

[0088] For 1000 g of hexamethylene diisocyanate with a total mass M, under stirring at 100 °C, 1 g of phenothiazine is added, 1.0 g of 2-ethylhexanoate of N,N,N-trimethyl-N-(2-hydroxypropyl)ammonium is added, and the proportion of the remaining mass M1 of HDI in the reaction system to the total mass M of the added HDI is quantitatively monitored by gel chromatography; when the remaining mass M1 of HDI in the system accounts for 30% of the total mass M of the added HDI, diisooctyl phosphate (molar ratio to 2-ethylhexanoate of N,N,N-trimethyl-N-(2-hydroxypropyl)ammonium is 1:1) is added to terminate the reaction; the unreacted HDI in the reaction system is distilled off in a two-stage thin-film evaporator at a temperature of 140 °C and a pressure of 0.3 mbar, and a comparative polyisocyanate composition 7 containing radiation-curable urethane groups is obtained.

[0089] Comparative Example 2

[0090] To control the content of the weight-average molecular weight of 264 ± 80, it was adjusted with the polyisocyanate composition of S2-1 in Example 2 to prepare a polyisocyanate composition with a higher content of the weight-average molecular weight of 264 ± 80. 40 g of the polyisocyanate composition of S2-1 in Example 2 was mixed with 160 g of the composition in Example 1, and the mixing ratio was 20:80. After mixing evenly, Comparative Polyisocyanate Composition 8 was obtained.

[0091] Comparative Example 3

[0092] Prepare a polyisocyanate composition with a low content of the weight-average molecular weight of 480 ± 80.

[0093] For 1000 g of hexamethylene diisocyanate in total mass M, under stirring at 100 °C, 1 g of phenothiazine was added, and 232 g of hydroxyethyl acrylate was added and reacted for 2 h; 1.0 g of 2-ethylhexanoate of N,N,N-trimethyl-N-(2-hydroxypropyl)ammonium was added to quantitatively monitor the proportion of the consumed mass M1 of HDI in the reaction system to the total mass M of the added HDI through gel chromatography; when the consumed mass M1 of HDI in the system accounted for 5% of the total mass M of the added HDI, dibutyl phosphate was added to terminate the reaction. Two-stage thin-film evaporator distillation was carried out at a temperature of 140 °C and a pressure of 0.3 mbar to remove the unreacted HDI in the reaction system, and Comparative Polyisocyanate Composition 9 was obtained, in which the peak content of the weight-average molecular weight of 480 ± 80 was about 5%.

[0094] Comparative Example 4

[0095] Prepare a polyisocyanate composition with a high content of the weight-average molecular weight of 480 ± 80.

[0096] For 1000 g of hexamethylene diisocyanate in total mass M, under stirring at 80 °C, 1 g of phenothiazine was added, and 232 g of hydroxyethyl acrylate was added and reacted for 2 hours; the temperature was raised to 120 °C, 0.5 g of zinc isooctanoate was added, and the proportion of the remaining mass M1 of HDI in the reaction system to the total mass M of the added HDI was quantitatively monitored through gel chromatography; when the remaining mass M1 of HDI in the system accounted for 90% of the total mass M of the added HDI, diisooctyl phosphate (molar ratio to zinc isooctanoate 1.2:1) was added to terminate the reaction; two-stage thin-film evaporator distillation was carried out at a temperature of 140 °C and a pressure of 0.3 mbar to remove the unreacted HDI in the reaction system, and Comparative Polyisocyanate Composition 10 containing radiation-curable urethane groups was obtained, in which the peak content of the weight-average molecular weight of 480 ± 80 was about 85%.

[0097] The characterization results of Polyisocyanate Compositions 1-10 are shown in Table 1 below:

[0098] Table 1

[0099]

[0100]

[0101] The polyisocyanate composition 1 - 10 was placed in an oven at 50 °C and stored for 30 days for storage stability testing. The results are shown in the following table:

[0102]

[0103] The content of the component peak with a weight - average molecular weight of 264 ± 80 affects the storage stability of the polyisocyanate. When its content is greater than 1%, the increase rate of the monomer content during storage at 50 °C is slow. When the content is greater than 10%, the system compatibility is poor, turbidity appears during storage, and even crystallization occurs during low - temperature storage. The component peak with a weight - average molecular weight of 480 ± 80 significantly affects the viscosity of the polyisocyanate. When no low - viscosity product is added additionally, the higher the peak area of this peak, the lower the viscosity of the product.

Claims

1. A polyisocyanate composition, characterized in that, the composition is a polyisocyanate composition obtained by reacting an aliphatic diisocyanate and / or an alicyclic diisocyanate with a hydroxy acrylate, and the composition has the following characteristics: a. The integral area of the component peak with a weight average molecular weight of 264 ± 80 accounts for 0.1 to 10% of the total peak area, preferably 0.5 to 8%, and more preferably 1 to 6%; b. The integral area of the peak of the component with a weight average molecular weight of 480 ± 80 accounts for 20 to 70% of the total peak area, and more preferably 30 to 60%.

2. The polyisocyanate composition according to claim 1, characterized in that, the viscosity of the polyisocyanate composition is less than or equal to 3000 mPa·s, preferably less than or equal to 2000 mPa·s.

3. The polyisocyanate composition according to claim 1 or 2, characterized in that, the aliphatic diisocyanate and / or alicyclic diisocyanate is an organic diisocyanate having 4 to 20 carbon atoms in the carbon skeleton in addition to the NCO group, and is preferably selected from one or more of hexamethylene diisocyanate, pentamethylene diisocyanate, isophorone diisocyanate, cyclohexyl dimethylene diisocyanate, dicyclohexylmethane diisocyanate, norbornane dimethylene diisocyanate, cyclohexyl diisocyanate and 2,4,4-trimethylhexane diisocyanate.

4. The polyisocyanate composition according to any one of claims 1-3, characterized in that, the hydroxy acrylate is prepared from acrylic acid or methacrylic acid and a diol having 2 to 10 carbon atoms, and is preferably one or more of hydroxyethyl acrylate and hydroxyethyl methacrylate.

5. A method for preparing the polyisocyanate composition according to any one of claims 1-4, characterized in that, the method is Preparation Method A or Preparation Method B; Preparation Method A includes the following steps: S1-1: After adding an inhibitor to an excess of diisocyanate, reacting with a hydroxy acrylate under heating conditions, and after complete conversion of the hydroxy acrylate, a prepolymer reaction solution is obtained; S1-2: Optionally adding a catalyst to the prepolymer reaction solution, and after the reaction reaches the conversion rate, adding a terminator; S1-3: Removing the unreacted diisocyanate monomer to obtain a polyisocyanate composition product; Preparation Method B includes the following steps: S2-1’: Preparing a polyisocyanate composition according to Preparation Method A; S2-1: Reacting a diisocyanate with a hydroxy acrylate to obtain a prepolymer reaction solution, and removing the unreacted monomer; S2-2: Blending the product of S2-1’ with the product of S2-1 to obtain a polyisocyanate composition product.

6. The method according to claim 5, characterized in that, in S1-1, the molar ratio of the diisocyanate to the hydroxy acrylate is (1 to 10):1, preferably (2 to 8):1, and more preferably (3 to 6):1; the reaction temperature is 50 to 100 °C, and the reaction time is 0.5 to 4 h.

7. The method according to claim 5, characterized in that, The inhibitor in S1-1 is a hydroquinone, 2,6-di-tert-butylphenol, nitrosamine, phenothiazine and its derivatives or phospholipid, and the dosage of the inhibitor is 0.001-2 wt% of the mass of the diisocyanate.

8. According to the method described in claim 5, characterized in that, the catalyst in S1-2 is selected from one or more of organotin compounds, organozinc compounds, alkali metal salts, tertiary amines and salt compounds; the organotin compounds are selected from dibutyltin dilaurate and stannous octoate; the organozinc compounds are selected from zinc isooctanoate, zinc octoate and zinc acetylacetonate; the alkali metal salt is sodium acetate; the tertiary amines and salt compounds are selected from 2-ethylhexanoate of N,N,N-trimethyl-N-(2-hydroxypropyl)ammonium, N,N,N-trimethyl-N-(2-hydroxypropyl)ammonium hydroxide, N,N,N-trimethyl-N-(2-hydroxypropyl)ammonium fluoride, and zinc isooctanoate and 2-ethylhexanoate of N,N,N-trimethyl-N-(2-hydroxypropyl)ammonium are further preferred; the dosage of the catalyst is 100-2000 ppm of the mass of the diisocyanate; the reaction temperature is 80-140 °C and the reaction time is 0.5-4 h.

9. According to the method described in claim 5, characterized in that, in S2-1, the molar ratio of the diisocyanate to the hydroxy acrylate is (1-5):1; the reaction temperature is 50-80 °C and the reaction time is 0.5-4 h.

10. According to the method described in claim 5, characterized in that, the blending mass ratio of the product of S2-1 to the product of S2-1' in S2-2 is 0.01-10%.

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