Flame-retardant polyurethane resin for lamination process, method of preparation and use

Abstract

The present application relates to a kind of flame-retardant polyurethane resin for laminating process and preparation method and application, wherein flame-retardant polyurethane resin includes isocyanate component and isocyanate reactive component, the isocyanate reactive component includes polyol, flame retardant, catalyst and processing aid;The isocyanate component is combined by polymeric MDI and MDI monomer, and the mass ratio is 4:1~1:4;The mass of the polyol is 60%~80% of the total mass of isocyanate reactive component, the mass of flame retardant is 10%~30% of the total mass of isocyanate reactive component, the mass of catalyst is 0.1%~5% of the total mass of isocyanate reactive component, and the mass of processing aid is 2%~10% of the total mass of isocyanate reactive component;The molar ratio of isocyanate group in the isocyanate component and active hydrogen atom in isocyanate reactive component is 1:1~5:1.

Description

Technical Field

[0001] This invention relates to the field of polyurethane resin technology, specifically to a flame-retardant polyurethane resin for lamination processes, its preparation method, and its applications. Background Technology

[0002] STM (Solid Molding Milling) is a polyurethane molding method. This method involves placing reinforcing fiber felt or fabric on one or both sides of a core layer (e.g., paper honeycomb, aluminum honeycomb, fiberglass, etc.), applying a polyurethane reaction mixture to the felt or fabric, placing the component coated with the reaction mixture in a mold, and laminating the component at a specific temperature. This allows the polyurethane reaction mixture to cure and form a polyurethane / polyisocyanurate interpenetrating three-dimensional structure. After demolding, the polyurethane laminated molded product is obtained. This method features high production speed, high efficiency, and strong structural performance of the finished product, and is specifically used for manufacturing automotive battery casings, energy storage structural components, and other similar products.

[0003] Currently, the lamination process resins on the market are mainly unsaturated and vinyl, but they have the following disadvantages: (1) The resin matrix is ​​defective, and the product performance cannot meet the product performance requirements; (2) The resin has a strong odor, which has a significant impact on the surrounding environment; (3) The resin impregnation of fibers is not ideal, the product porosity is high, and the air tightness is insufficient; (4) The resin working time and molding speed are not well matched, making it difficult to achieve high quality and high production speed; (5) In the large area and complex structure of the mold cavity, it is impossible to predict and control, the resin flow is uneven, the product defects are large, and the product yield is low. Summary of the Invention

[0004] To address the aforementioned problems in the prior art, this invention provides a flame-retardant polyurethane resin for lamination processes, its preparation method, and its application. This resin can replace existing resins and meet market demands.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A flame-retardant polyurethane resin for lamination processes includes an isocyanate component and an isocyanate reactive component, wherein the isocyanate reactive component includes a polyol, a flame retardant, a catalyst, and a processing aid. The isocyanate component is composed of polymeric MDI and MDI monomers in a mass ratio of 4:1 to 1:4; the NCO content of the isocyanate component is 31.2% to 33.5%, preferably 31.3% to 32.5%; within the scope of this invention, the viscosity of the mixture of the two isocyanates is very low, which is beneficial for reducing the viscosity after mixing with the isocyanate reactive component and improving the wetting effect of the mixture on the fiber. This satisfies the requirements for the production of products with fatigue resistance mechanical properties. The viscosity of the isocyanate component at 25°C is 15 to 200 mPa·s, preferably 30 to 150 mPa·s.

[0006] The mass of the polyol is 60% to 80% of the total mass of the isocyanate reactive components, the mass of the flame retardant is 10% to 30% of the total mass of the isocyanate reactive components, the mass of the catalyst is 0.1% to 5% of the total mass of the isocyanate reactive components, and the mass of the processing aid is 2% to 10% of the total mass of the isocyanate reactive components. Preferably, the mass of the polyol is 70% to 80% of the total mass of the isocyanate reactive components, the mass of the flame retardant is 15% to 25% of the total mass of the isocyanate reactive components, the mass of the catalyst is 0.4% to 4% of the total mass of the isocyanate reactive components, and the mass of the processing aid is 3% to 7% of the total mass of the isocyanate reactive components. The molar ratio of isocyanate groups in the isocyanate component to active hydrogen atoms in the isocyanate reactive component is 1:1 to 5:1, preferably 2:1 to 3:1.

[0007] The polymeric MDI is an isocyanate compound with different functionalities. It can be obtained using methods commonly used in the art or through commercial procurement. The polymeric MDI and MDI monomers can be commercially available products, such as: polymeric MDI from Wanhua Chemical Group Co., Ltd. (PM-100, PM-130, PM-200, PM-300, PM-400, PM-2010); and MDI monomers from Wanhua Chemical Group Co., Ltd. (MDI-50, MDI-100).

[0008] The isocyanate component further includes organic isocyanate monomers, isocyanate prepolymers, and isocyanate modifiers. These include one or more of toluene diisocyanate (TDI), isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), dicyclohexylmethane diisocyanate (HMDI), naphthalene diisocyanate (NDI), terephthalic diisocyanate (PPDI), 1,4-cyclohexane diisocyanate (CHDI), phenylenediamine diisocyanate (XDI), cyclohexane diisocyanate (HXDI), trimethyl-1,6-hexamethylene diisocyanate (TMHDI), tetramethyl-m-phenylenediamine diisocyanate (TMXDI), norbornane diisocyanate (NBDI), dimethylbiphenyl diisocyanate (TODI), and methylcyclohexyl diisocyanate (HTDI), as well as one or more of prepolymers and modified products of these monomers.

[0009] The polyols include polyether polyols, polyester polyols, polycarbonate polyols, bio-based polyols, and other types of polyols. The polyether polyols are selected from compounds obtained using polyols as initiators and epoxides as polymerization monomers. The initiators include one or more of ethylene glycol, propylene glycol, 1,4-butanediol, 1,3-butanediol, 1,2-butanediol, hexanediol, diethylene glycol, triethylene glycol, dipropylene glycol, diethylene glycol, neopentyl glycol, glycerol, trimethylolpropane, pentaerythritol, sorbitol, and sucrose. The epoxides include one or more of ethylene oxide, propylene oxide, and epoxide.

[0010] The isocyanate reactive component further includes a small molecule alcohol with a functionality of 2-3 and a molecular weight of 62-104. The small molecule alcohol can be any commonly used in the art, and there are no particular limitations. For example, small molecule alcohols include one or more of ethylene glycol, propylene glycol, 1,4-butanediol, 1,3-butanediol, 1,2-butanediol, pentanediol, hexanediol, diethylene glycol, triethylene glycol, dipropylene glycol, diethylene glycol, neopentanediol, glycerol, and trimethylolpropane. These small molecule alcohols can be used alone or in combination. The small molecule alcohol can play a role in extending the polymer chain, cross-linking, and increasing the molecular weight.

[0011] The flame retardant refers to a flame retardant that can improve the flame retardant properties of resin, including flame retardant polyols and self-made reactive substances with flame retardant effects, such as any one or a combination of tris(2-chloropropyl) phosphate, dipentaerythritol diphosphite, tris(2-chloroethyl) phosphate or tris(2,3-dichloropropyl) phosphate, and may also include any one or a combination of ammonium polyphosphate, ammonium phosphate salt, calcium phosphate or magnesium phosphate.

[0012] Catalysts refer to a class of compounds that exhibit catalytic activity towards isocyanate groups and active hydrogen atoms. Examples include, but are not limited to, organometallic catalysts and amine catalysts. Specifically, they include one or more of the following: triethylamine, tributylamine, triethylenediamine, N-ethylmorpholine, N,N,N',N'-tetramethylethylenediamine, pentamethyldiethylenetriamine, N,N-methylaniline, N,N-dimethylaniline, tin(II) acetate, tin(II) octoate, tin ethylhexanoate, tin laurate, dibutyltin oxide, dibutyltin dichloride, dibutyltin diacetate, dibutyltin maleate, and dioctyltin diacetate.

[0013] In some embodiments, the catalyst includes a thermosensitive catalyst, and the activation temperature of the thermosensitive catalyst (the catalyst does not have catalytic activity when the temperature is below the activation temperature; the catalyst has catalytic activity when the temperature is above the activation temperature) is not lower than 50°C, preferably 50–90°C. The specific type of thermosensitive catalyst is not particularly limited, but it must meet the condition that the activation temperature is not lower than 50°C, preferably 50–90°C.

[0014] Thermosensitive catalysts refer to a class of catalysts that exhibit significant catalytic activity at or within a specific temperature range. Examples include, but are not limited to, one or more of blocked amine catalysts, blocked imidium catalysts, and sterically hindered organometallic catalysts. More specific examples include, but are not limited to, one or more of the following: phenol-terminated 1,8-diazabicyclo[5.4.0]undec-7-ene, formic acid-terminated triethylenediamine, triethylenediamine dicyanoacetate, formate or phenolate or isooctanoate of dimethylcyclohexylamine, dithiol dioctyltin, and bis(dimethylaminoethyl) ether derivatives. To ensure a low initial viscosity of the reaction system, the reactants are maintained at 40°C or above before the reaction, and the viscosity increases slowly in the initial stage of injection, maintaining relatively high fluidity for a relatively long period. Therefore, the activation temperature of the selected catalyst should not be lower than 50°C to prevent deactivation of the catalyst before the reactants are injected, and to prevent rapid catalytic reaction in the initial stage of reactant injection from causing a rapid increase in system viscosity, resulting in product defects such as poor wetting of reinforcing materials.

[0015] The catalysts described in this invention also include catalysts capable of converting isocyanates into trimer structures. Examples of trimer catalysts include, but are not limited to, tris(dialkylaminoalkyl)-s-hexahydrotriazine, such as 1,3,5-tris(N,N-dimethylaminopropyl)-s-hexahydrotriazine, potassium salts of carboxylic acids (e.g., potassium acetate, potassium neopentanoate, potassium octanoate, potassium triethylacetate, potassium neoheptanoate, potassium neooctanoate, potassium ethylhexanoate, potassium acetate, or potassium isooctanoate), tetraalkylammonium hydroxides, such as tetramethylammonium hydroxide, alkali metal hydroxides such as sodium hydroxide, alkali metal alkoxides such as sodium methoxide and potassium isopropoxide, alkali metal salts of long-chain fatty acids having 10 to 20 carbon atoms and, in some embodiments, side hydroxyl groups, quaternary ammonium carboxylates (e.g., (2-hydroxypropyl)trimethylammonium 2-ethylhexanoate (“TMR”), (2-hydroxypropyl)trimethylammonium formate (“TMR-2”), tetramethylnepentanoate, tetramethyltriethylacetate), and combinations thereof.

[0016] Processing aids may optionally include one or more of the following: internal release agent, dispersant, drying agent, dye, defoamer, leveling agent, wetting agent, coupling agent, dehydrating agent, antioxidant, anti-hydrolysis agent, antistatic agent, viscosity reducer, and filler. Adding an internal release agent can reduce the demolding time of the polyurethane material produced in the reaction, thereby improving production efficiency. Internal release agents can be those conventionally used in the art, without particular limitation. Examples include, but are not limited to, condensation products with ester groups, polysiloxane compounds, higher fatty alcohols, higher fatty amines, zinc stearate, etc. These internal release agents can be used alone or in combination.

[0017] In some embodiments, the isocyanate component is heated to approximately 25°C, and the isocyanate reactive component is also heated to approximately 25°C before being mixed. This invention uses an isocyanate component with a specific composition, and mixing them under the aforementioned temperature control allows for controlled viscosity of the resulting reaction mixture. This promotes rapid wetting of the reinforcing material within the mold by the reactants, reducing defects in the product. Timing is started after mixing the isocyanate component and the isocyanate reactive component; the viscosity of the resulting mixture within 30 seconds is 50–500 mPa·s, preferably 100–200 mPa·s.

[0018] The flame-retardant polyurethane resin described in this invention can be used to prepare polyurethane laminated molded products, and the preparation method includes the following steps: (1) Cut and pre-lay the reinforcing material into shape; (2) Mix the isocyanate component and the isocyanate reactive component; (3) The resulting mixture is uniformly sprayed onto the surface of the reinforcing material using a spraying device; (4) Then the reinforcing material coated with the polyurethane reaction mixture is transferred into a mold; (5) The reinforcing material is laminated at a certain temperature to cure the polyurethane reaction mixture and form a three-dimensional structure. After demolding, the polyurethane laminated molded product is obtained.

[0019] The reinforcing material can be selected from materials commonly used in the art, including but not limited to glass fiber, carbon fiber, metal fiber, natural fiber, aramid fiber, and polyethylene fiber. These reinforcing materials can be used alone or in combination. Preferably, the reinforcing material is selected from glass fiber and / or carbon fiber. In some embodiments, the reinforcing material accounts for 10-90% of the total mass of the polyurethane composite material, preferably 45-80%.

[0020] In some embodiments, the reaction is carried out in a mold at 50–130°C (preferably 80–120°C) for a reaction time (or demolding time) of 2.5–5 min.

[0021] The isocyanate index of the polyurethane composition is 100-300, and better release properties can be obtained by using such polyurethane compositions.

[0022] It should be noted that the preparation method is applicable to non-foaming systems or low-foaming systems, that is, the reactants contain virtually no water or less than 0.5% water. Generally, non-foaming systems are more suitable for this technical solution.

[0023] The composite material prepared by the method of this invention has the characteristics of excellent mechanical properties, high flame retardancy, and excellent surface quality.

[0024] Compared with the prior art, the beneficial effects of the present invention are: (1) The flame-retardant polyurethane resin of the present invention can meet the UL-94:V0 flame retardant requirements under a thickness of 1.5mm in the cured composite material product. At the same time, it can have good mechanical properties and process properties, meet the performance requirements of electric vehicle battery shells, replace traditional process products, improve product performance, reduce costs, and improve production efficiency.

[0025] (2) The method of the present invention can improve the wetting effect of the mixture on the reinforcing material, and is particularly suitable for the STM process that requires rapid curing. It reduces product defects, improves production efficiency, and the products have excellent toughness and good mechanical properties, which can meet the requirements of flame retardancy in product production. Detailed Implementation

[0026] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0027] The raw materials used in the following examples and comparative examples include: Polymer MDI, WANNATE PM200, NCO content 31.2 wt%, purchased from Wanhua Chemical. MDI monomer, WANNATE MDI50, NCO content 33.5 wt%, purchased from Wanhua Chemical; NJ-8238: Polyether polyol with a hydroxyl value of 380 mgKOH / g, purchased from Jurong Ningwu New Materials Co., Ltd. NJ-405A: Polyether polyol with a hydroxyl value of 450 mgKOH / g, purchased from Jurong Ningwu New Materials Co., Ltd. NJ-220: Polyether polyol with a hydroxyl value of 56 mgKOH / g, purchased from Jurong Ningwu New Materials Co., Ltd. PCE-2017E: Polyether carbonate polyol, with a hydroxyl value of 52 mg KOH / g, purchased from Changhua Chemical Technology Co., Ltd. Epoxidized soybean oil: purchased from Jiangsu Leien Environmental Protection Technology Co., Ltd.; NJ-301: Polyether polyol with a hydroxyl value of 1120 mgKOH / g, purchased from Jurong Ningwu New Materials Co., Ltd. TCPP: Flame retardant, purchased from Qingdao Lianmei Chemical Co., Ltd. DMMP: Flame retardant, purchased from Qingdao Lianmei Chemical Co., Ltd. WSFR-780LS: Flame retardant, purchased from Zhejiang Wansheng Co., Ltd. BYK-9912: Internal mold release agent, purchased from BYK Chemicals; BH8820: Homemade black pigment. Weigh 20% carbon black by weight, add 80% difunctional polyether polyol with a molecular weight of 1000, and then add 3% BYK-163 dispersant (purchased from BYK Chemical Co., Ltd.). Use a three-roll mill to grind the pigment paste to a particle size of ≤20um. YN-Bi2010: Organic bismuth catalyst; purchased from Umicore Metals International Trading Co., Ltd. K-15: Trimerization catalyst, purchased from Air Products.

[0028] Table 1 Resin formulations for the examples and comparative examples

[0029] Wherein, R value is the molar ratio of isocyanate groups in the isocyanate component to active hydrogen atoms in the isocyanate reactive component.

[0030] Honeycomb sandwich panels were produced using flame-retardant polyurethane resins from Examples 1 and 1-5: the layup consisted of 4 × 400 g / m³ layers. 2 Fiberglass woven fabric. Using the reaction mixture shown in Table 1 at 320 g / m²... 2 The original sandwich structure was sprayed onto the surface. The coated sandwich structure was then placed in a mold for 180 seconds to cure and demold. The fabrication method employed a resin lamination process (STM), with the following specific steps: At 25°C, the isocyanate component and the isocyanate reactive component are mixed and stirred evenly for later use. The isocyanate component and the isocyanate reactive component are mixed evenly through the static mixer of a high-pressure resin transfer molding equipment. Then, the polyurethane reaction mixture is applied to the reinforcing fiber or reinforcing fiber fabric. The part covered with the polyurethane reaction mixture is then placed in a mold, and the mold temperature is controlled at 120°C for reaction. After the reaction is completed for 3 minutes, the polyurethane composite material is obtained.

[0031] In Example 1 and Comparative Examples 1-5, the mass ratio of reinforcing material to flame-retardant polyurethane resin was 60:40.

[0032] In Examples 1, 1, 4, and 5, ammonia-initiated polyether polyols were used in combination with various flame retardants to produce a synergistic flame-retardant effect and improve the flame-retardant performance of the products. Polyether carbonate polyols were also used to improve the various mechanical properties of the products. The combined use resulted in overall performance superior to conventional products, as shown in Table 2.

[0033] Table 2

[0034] The results above show that the honeycomb sandwich panel prepared using the flame-retardant polyurethane resin of the present invention can meet the UL-94:V0 flame retardant requirements, while also possessing good mechanical properties and meeting the requirements of STM process performance.

[0035] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A flame-retardant polyurethane resin for lamination processes, characterized in that: It includes an isocyanate component and an isocyanate reactive component, wherein the isocyanate reactive component includes polyols, flame retardants, catalysts and processing aids; The isocyanate component is composed of polymeric MDI and MDI monomers in a mass ratio of 4:1 to 1:

4. The mass of the polyol is 60% to 80% of the total mass of the isocyanate reactive components, the mass of the flame retardant is 10% to 30% of the total mass of the isocyanate reactive components, the mass of the catalyst is 0.1% to 5% of the total mass of the isocyanate reactive components, and the mass of the processing aid is 2% to 10% of the total mass of the isocyanate reactive components. The molar ratio of isocyanate groups in the isocyanate component to active hydrogen atoms in the isocyanate reactive component is 1:1 to 5:

1.

2. The flame-retardant polyurethane resin according to claim 1, characterized in that: The polymeric MDI is an isocyanate compound with different functionalities.

3. The flame-retardant polyurethane resin according to claim 2, characterized in that: The polymeric MDI includes PM-100, PM-130, PM-200, PM-300, PM-400, and PM-2010 from Wanhua Chemical Group Co., Ltd.; the MDI monomers include MDI-50 and MDI-100 produced by Wanhua Chemical Group Co., Ltd.

4. The flame-retardant polyurethane resin according to claim 1, characterized in that: The isocyanate component also includes organic isocyanate monomers, isocyanate prepolymers, and isocyanate modifiers.

5. The flame-retardant polyurethane resin according to claim 4, characterized in that: The isocyanate component includes one or more of toluene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, naphthalene diisocyanate, terephthalic diisocyanate, 1,4-cyclohexane diisocyanate, phenylenediamine diisocyanate, cyclohexane diisocyanate, trimethyl-1,6-hexamethylene diisocyanate, tetramethyl-isophthalic acid diisocyanate, norbornane diisocyanate, dimethyl biphenyl diisocyanate, and methylcyclohexyl diisocyanate, as well as one or more of prepolymers and modified products of such monomers.

6. The flame-retardant polyurethane resin according to claim 1, characterized in that: The polyols include polyether polyols, polyester polyols, polycarbonate polyols, and bio-based polyols; the polyether polyols are selected from compounds obtained by using polyols as initiators and epoxides as polymerization monomers, the initiators include one or more of ethylene glycol, propylene glycol, 1,4-butanediol, 1,3-butanediol, 1,2-butanediol, hexanediol, diethylene glycol, triethylene glycol, dipropylene glycol, diethylene glycol, neopentyl glycol, glycerol, trimethylolpropane, pentaerythritol, sorbitol, and sucrose, and the epoxides include one or more of ethylene oxide, propylene oxide, and epoxide butane.

7. The flame-retardant polyurethane resin according to claim 1, characterized in that: The isocyanate reactive component further includes a small molecule alcohol with a functionality of 2-3 and a molecular weight of 62-104; the small molecule alcohol includes one or more of ethylene glycol, propylene glycol, 1,4-butanediol, 1,3-butanediol, 1,2-butanediol, pentanediol, hexanediol, diethylene glycol, triethylene glycol, dipropylene glycol, diethylene glycol, neopentanediol, glycerol, and trimethylolpropane.

8. The flame-retardant polyurethane resin according to claim 1, characterized in that: The flame retardant includes any combination of several of the following: tris(2-chloropropyl) phosphate, dipentaerythritol diphosphite, tris(2-chloroethyl) phosphate or tris(2,3-dichloropropyl) phosphate, ammonium polyphosphate, ammonium phosphate salt, calcium phosphate or magnesium phosphate. The catalyst comprises one or more of the following: triethylamine, tributylamine, triethylenediamine, N-ethylmorpholine, N,N,N',N'-tetramethylethylenediamine, pentamethyldiethylenediamine, N,N-methylaniline, N,N-dimethylaniline, tin(II) acetate, tin(II) octoate, tin ethylhexanoate, tin laurate, dibutyltin oxide, dibutyltin dichloride, dibutyltin diacetate, dibutyltin maleate, and dioctyltin diacetate. The processing aids include one or more of the following: internal release agent, dispersant, desiccant, dye, defoamer, leveling agent, wetting agent, coupling agent, dehydrating agent, antioxidant, anti-hydrolysis agent, antistatic agent, viscosity reducer, and filler.

9. A method for preparing a polyurethane laminated molded article using the flame-retardant polyurethane resin according to any one of claims 1-8, characterized in that, Includes the following steps: (1) Cut and pre-lay the reinforcing material into shape; (2) Mix the isocyanate component and the isocyanate reactive component; (3) The resulting mixture is uniformly sprayed onto the surface of the reinforcing material using a spraying device; (4) Then the reinforcing material coated with the polyurethane reaction mixture is transferred into a mold; (5) The reinforcing material is laminated at 50℃~130℃ to cure the polyurethane reaction mixture and form a three-dimensional structure. After demolding, the polyurethane laminated molded product is obtained.

10. The use of the flame-retardant polyurethane resin according to any one of claims 1-8 in the preparation of polyurethane laminated molded articles.

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