CN118974130A - Panel structure, method for its preparation and use as automotive component - Google Patents

Abstract

The present invention discloses a panel structure, a preparation method thereof and a use thereof as an automobile component. The present invention relates to an isocyanate reactive composition for making a polyurethane resin, the composition comprising: A. castor oil; B. at least one polyether polyol having an average functionality of 2.0 to 4.0; C. at least one chain extender; and D. at least two catalysts selected from an amine catalyst and/or an alkyl tin catalyst.

Description

Panel structure, method for its preparation and use as automotive component

Technical Field

The present invention relates to an isocyanate-reactive composition for producing a polyurethane resin, a panel construction, a process for its preparation and its use as an automotive component.

Background Art

Panel construction is a molded part used as a structural reinforcement for an automobile, for example an underbody panel is often used to reinforce the steering wheel panel. Typically, these panels consist of a mat saturated with a polyurethane resin in a closed mold.

These composite materials and methods for producing them are well known in the prior art. For example, US9375893B2 discloses a lightweight, strong and durable automotive panel, in particular an underbody shield obtained using a panel construction comprising a first composite fiber mat layer and a second composite fiber mat layer, the first composite fiber mat layer and the second composite fiber mat layer comprising a nonwoven fabric.

Prior art panel constructions are represented by honeycomb based composite constructions. For example, EP 1 544 179 A2 relates to a honeycomb structure comprising a supporting substrate of glass fibers impregnated with a polyamide-imide resin prepolymer.

Among the available technologies for producing such panels, spray transfer molding (STM) is a fast and efficient method for manufacturing panels with low thickness, which is highly desirable for automotive applications. However, spray molding technology involves the use of atomizers that are generally incompatible with high viscosity (>2000cps at 23°C) resins.

Recently, US20210339484A1 identified a polyurethane resin-honeycomb composite panel having a reduced thickness while providing acceptable structural benefits.

However, a problem with existing resins is their poor adhesion, particularly to thermoplastics. In addition, amid growing environmental concerns, there is a need to produce environmentally sustainable composite materials. It is therefore an object of the present invention to provide a polyurethane resin suitable for automotive panel construction and for spray molding applications, which has high adhesion to thermoplastics, has high mat wettability, and at the same time has lower environmental toxicity than conventional polyurethane resins.

Summary of the invention

Surprisingly, it has been found that the above objects are met by providing an isocyanate reactive composition for making polyurethane resins as described below, comprising: A. castor oil; B. at least one polyether polyol having an average functionality of 2.0 to 4.0; C. at least one chain extender; and D. at least two catalysts selected from amine catalysts and/or alkyl tin catalysts. The composition provides low viscosity (≤ 2000 cps at 23°C), better moldability, higher wettability, no drip performance, higher adhesion to thermoplastics, while maintaining lower environmental toxicity compared to conventional polyurethane resins.

Thus, in one aspect, the presently claimed invention is directed to an isocyanate-reactive composition for making a polyurethane resin, the composition comprising: A. castor oil; B. at least one polyether polyol having an average functionality of 2.0 to 4.0; C. at least one chain extender; and D. at least two catalysts selected from an amine catalyst and/or an alkyl tin catalyst.

In another aspect, the presently claimed invention is directed to a polyurethane resin obtainable by a process comprising reacting: A. an isocyanate; and B. an isocyanate-reactive composition as described herein.

In yet another aspect, the presently claimed invention relates to a panel construction comprising: A. at least one cushion layer; B. a polyurethane film prepared from a polyurethane resin composition obtainable by a process comprising reacting: a. an isocyanate, b. an isocyanate-reactive composition as described herein; and C. a honeycomb layer adjacent to the cushion layer and in contact with the polyurethane film, wherein the polyurethane resin composition is sprayed onto the at least one cushion layer to form the polyurethane film.

In another aspect, the presently claimed invention relates to a method for preparing a panel construction, the method comprising the following steps: (S1) spraying a polyurethane resin composition onto at least one surface of a cushion layer, wherein the polyurethane resin composition can be obtained by a method comprising reacting the following substances: a. an isocyanate, b. an isocyanate-reactive composition as described herein, wherein the polyurethane resin composition forms a polyurethane film on the at least one surface of the cushion layer; and obtaining a pre-impregnated body, and (S2) compression molding the pre-impregnated body together with a honeycomb layer.

In another aspect, the presently claimed invention relates to the use of a panel construction as described herein or as obtained by a method as described herein as an automotive component.

In yet another aspect, the presently claimed invention relates to an automotive component comprising a panel construction as described herein or as obtained by a method as described herein.

DETAILED DESCRIPTION

Before describing the inventive compositions and formulations of the present invention, it should be understood that the present invention is not limited to the specific compositions and formulations described, as such compositions and formulations may of course vary. It should also be understood that the terminology used herein is not intended to be limiting, as the scope of the present invention will be limited only by the appended claims.

As used herein, the terms "comprising" or "comprises" and "comprised of" are synonymous with "including" or "includes", or "containing" or "contains", and are inclusive or open-ended and do not exclude additional, unrecited components, elements, or method steps. It should be understood that as used herein, the terms "comprising" or "comprises" and "comprised of" include the term "consisting of" or "consists of".

In addition, the terms "first", "second", "third" or "(a)", "(b)", "(c)", "(d)", etc. in the specification and claims are used to distinguish between similar elements and are not necessarily used to describe a sequential or chronological order. It should be understood that the terms so used are interchangeable where appropriate, and that the embodiments of the invention described herein are capable of operating in other sequences than those described or shown herein. If the terms "first", "second", "third" or "(A)", "(B)" and "(C)" or "(a)", "(b)", "(c)", "(d)", "i", "ii", etc. refer to steps of a method or use or an assay, there is no temporal or temporal coherence between these steps, that is, these steps may be performed simultaneously, or there may be time intervals of seconds, minutes, hours, days, weeks, months or even years between such steps, unless otherwise indicated in this application as described above or below.

In the following paragraphs, different aspects of the present invention are defined in more detail. Each aspect so defined can be combined with any other one or more aspects, unless the contrary is clearly indicated. In particular, any feature indicated as preferred or advantageous can be combined with any other one or more features indicated as preferred or advantageous.

Reference to "one embodiment" or "an embodiment" throughout this specification means that the specific features, structures or characteristics described in conjunction with the embodiment are included in at least one embodiment of the present invention. Therefore, the phrases "in one embodiment" or "in one embodiment" appearing throughout this specification do not necessarily all refer to the same embodiment, but may refer to the same embodiment. In addition, in one or more embodiments, specific features, structures or characteristics may be combined in any suitable manner, as will be apparent to those skilled in the art based on this disclosure. In addition, although some embodiments described herein include some features but not other features included in other embodiments, as will be understood by those skilled in the art, the combination of features of different embodiments is intended to be within the scope of the present invention and to form different embodiments. For example, in the appended claims, any of the claimed embodiments may be used in any combination.

Furthermore, ranges defined throughout the specification also include the endpoints, ie, a range of 1 to 10 means that both 1 and 10 are included in the range. For the avoidance of doubt, the applicant shall have any equivalent rights under applicable law.

One aspect of the present invention relates to an isocyanate-reactive composition for making a polyurethane resin, the composition comprising: A. castor oil; B. at least one polyether polyol having an average functionality of 2.0 to 4.0; C. at least one chain extender; and D. at least two catalysts selected from amine catalysts and/or alkyl tin catalysts.

According to the invention, the composition comprises castor oil. Preferably, the castor oil comprises triglycerides of ricinoleic acid in an amount of >50% by weight relative to the castor oil. More preferably, the castor oil comprises triglycerides of ricinoleic acid in an amount of >60% by weight relative to the castor oil, even more preferably in an amount of >70% by weight, even more preferably in an amount of >80% by weight, even more preferably in an amount of 90% by weight.

Preferably, the castor oil content is in the range of 25% to 60% by weight relative to the total weight of the composition. More preferably, the castor oil content is in the range of 28% to 45% by weight, even more preferably 30% to 40% by weight, most preferably 32% to 40% by weight relative to the total weight of the composition.

According to the present invention, the composition comprises at least one polyether polyol having an average functionality of 2.0 to 4.0. Preferably, the polyether polyol is obtainable by known methods, for example by anionic polymerization or cationic polymerization.

For anionic polymerization, the polymerization of alkylene oxides having 2 to 4 carbon atoms in the alkylene moiety is carried out in the presence of an alkali metal hydroxide (e.g., sodium hydroxide or potassium hydroxide) or an alkali metal alkoxide (e.g., sodium methoxide, sodium ethoxide, potassium ethoxide or potassium isopropoxide) as a catalyst with the addition of at least one starter molecule containing 1 to 4 reactive hydrogen atoms in bonded form, preferably 2 to 3 reactive hydrogen atoms in bonded form and more preferably 2 reactive hydrogen atoms in bonded form.

For cationic polymerization, an alkylene oxide having 2 to 4 carbon atoms in the alkylene moiety is polymerized with a Lewis acid such as antimony pentachloride, boron fluoride etherate, etc. or bleaching earth as a catalyst. As a catalyst, double metal cyanide compounds (called DMC catalysts) can also be used.

The starter molecules are generally selected such that their average functionality is preferably from 2.0 to 8.0, or from 3.0 to 8.0. Optionally, mixtures of suitable starter molecules are used.

The starting molecules used for the polyether polyols include amine-containing starting molecules and hydroxyl-containing starting molecules. Suitable amine-containing starting molecules include, for example, aliphatic diamines and aromatic diamines, such as ethylenediamine, propylenediamine, butylenediamine, hexamethylenediamine, phenylenediamine, toluenediamine, diaminodiphenylmethane and isomers thereof.

Other suitable starter molecules include alkanolamines, such as ethanolamine, N-methylethanolamine and N-ethylethanolamine, dialkanolamines, such as diethanolamine, N-methyldiethanolamine and N-ethyldiethanolamine, and trialkanolamines, such as triethanolamine and ammonia.

Preferred amine-containing starter molecules include ethylenediamine, phenylenediamine, toluenediamine or isomers thereof. A particularly preferred amine-containing starter molecule is ethylenediamine.

Hydroxyl-containing starter molecules include sugars, sugar alcohols, such as glucose, mannitol, sucrose, pentaerythritol, sorbitol; polyphenols, resols (e.g., oligomeric condensation products formed from phenol and formaldehyde), trimethylolpropane, glycerol, glycols (such as ethylene glycol, propylene glycol and their condensation products (such as polyethylene glycols and polypropylene glycols, e.g., diethylene glycol, triethylene glycol, dipropylene glycol)) and water or combinations thereof.

Preferred hydroxyl-containing starter molecules are sugars and sugar alcohols, such as sucrose, sorbitol, glycerol, pentaerythritol, trimethylolpropane, and mixtures thereof. In some embodiments, the hydroxyl-containing starter molecules are sucrose, glycerol, pentaerythritol, and trimethylolpropane.

Suitable alkylene oxides having 2 to 4 carbon atoms are, for example, ethylene oxide, propylene oxide, tetrahydrofuran, 1,2-butylene oxide, 2,3-butylene oxide and styrene oxide. The alkylene oxides can be used alone, in alternation and in succession or as a mixture. Preferred alkylene oxides are propylene oxide and/or ethylene oxide. In some preferred embodiments, the alkylene oxide is a mixture of ethylene oxide and propylene oxide, containing more than 50% by weight of propylene oxide.

Preferably, the polyether polyol has a hydroxyl number of 15 to 1800 mg KOH/g as determined by DIN 53240. More preferably, the polyether polyol has a hydroxyl number of 45 to 1700 mg KOH/g, even more preferably 60 to 1600 mg KOH/g, more preferably 100 to 1500 mg KOH/g, even more preferably 500 to 1300 mg KOH/g, more preferably 500 to 1100 mg KOH/g, most preferably 500 to 1000 mg KOH/g as determined by DIN 53240.

Preferably, the polyether polyol has a weight average molecular weight in the range of 50 to 250 g/mol as determined by gel permeation chromatography. More preferably, the polyether polyol has a weight average molecular weight in the range of 80 to 220 g/mol, even more preferably 100 to 200 g/mol, most preferably 120 to 200 g/mol as determined by gel permeation chromatography.

Preferably, relative to the total weight of the composition, the total polyether polyol content is in the range of 35 wt % to 65 wt %. More preferably, relative to the total weight of the composition, the total polyether polyol content is in the range of 38 wt % to 55 wt %, even more preferably 40 wt % to 50 wt %.

Preferably, the weight ratio of at least one polyether polyol to castor oil is in the range of 0.5 to 6.0. More preferably, the weight ratio of at least one polyether polyol to castor oil is in the range of 0.7 to 4.8, even more preferably 0.9 to 3.5.

According to the present invention, the composition comprises at least one chain extender. The chain extender is different from the polyether polyol. The chain extender is preferably a low molecular weight compound having at least two isocyanate reactive groups and a molecular weight of less than 350 g/mol, more preferably 60 g/mol to less than 300 g/mol, even more preferably 60 g/mol to less than 200 g/mol. The chain extender and/or crosslinker used are preferably alkanolamines, and in particular diols and/or triols having a molecular weight preferably of 60 g/mol to 300 g/mol. These chain extenders and/or crosslinkers can be added in suitable amounts, and they are known to those skilled in the art. Preferably, a difunctional chain extender, a trifunctional crosslinker and a higher functional crosslinker can be added, or, if appropriate, a mixture thereof.

In the case of using low molecular weight chain extenders and/or crosslinkers, chain extenders known in the context of polyurethane production can be used, whereas the chain extender has a functionality of 2 and the crosslinker has a functionality of 3 or more. Chain extenders and/or crosslinkers can be used to adjust mechanical properties such as hardness or elongation. This is known to those skilled in the art. Examples of chain extenders and crosslinkers would include aliphatic, cycloaliphatic and/or araliphatic or aromatic diols having 2 to 14 carbon atoms, preferably 2 to 10 carbon atoms, such as ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,10-decanediol and bis(2-hydroxyethyl)hydroquinone, 1,2-dihydroxycyclohexane, 1,3-dihydroxycyclohexane, 1,4-dihydroxycyclohexane, diethylene glycol, dipropylene glycol, tripropylene glycol, triols (such as 1,2,4-trihydroxycyclohexane, 1,3,5-trihydroxycyclohexane, glycerol and trimethylolpropane), and low molecular weight hydroxyl-containing polyalkylene oxides based on ethylene oxide and/or 1,2-propylene oxide and the aforementioned diols and/or triols as starting molecules. Further possible low molecular weight chain extenders and/or crosslinkers are described, for example, in "Kunststoffhandbuch, Volume 7, Polyurethanes", Carl Hanser Verlag, 3rd edition, 1993, sections 3.2 and 3.3.2. If a chain extender is used, it is preferably selected from diethylene glycol, ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol or diethyltoluenediamine. More preferably, the chain extender is selected from diethylene glycol, ethylene glycol, diethyltoluenediamine or 1,4-butanediol. Even more preferably, the chain extender is selected from diethyltoluenediamine or diethylene glycol, most preferably, the chain extender is selected from diethylene glycol.

Preferably, commercially available chain extenders reactive toward isocyanates may also be used, for example BASF's and

Preferably, the at least one chain extender content is in the range of 1% to 15% by weight relative to the total weight of the composition. More preferably, the at least one chain extender content is in the range of 1% to 12% by weight, even more preferably 2% to 10% by weight, even more preferably 2% to 8% by weight relative to the total weight of the composition.

According to the present invention, the composition comprises at least two catalysts selected from amine catalysts and/or alkyl tin catalysts.

Preferably, the amine catalyst is selected from diethyltoluenediamine, 4,4'-methylenebis(2-methylcyclohexyl-amine) or 1-[bis[3-(dimethylamino)propyl]amino]-2-propanol.

Preferably, the alkyl tin catalyst is selected from a methyl organotin catalyst, a butyl organotin catalyst or an octyl organotin catalyst.

Methyl organotin catalysts well known in the art are suitable for the present application. Preferably, the methyl organotin catalyst is dimethyltin diceneodecanoate.

Butyl organotin catalysts well known in the art are suitable for the present application. Preferably, the butyl organotin catalyst is selected from dibutyltin dilaurate.

Octyl organotin catalysts well known in the art are suitable for the present application. Preferably, the octyl organotin catalyst is selected from dioctyltin dithioglycolate or dioctyltin mercap-tide.

Preferably, the alkyltin catalyst is selected from dimethyltin diceneodecanoate, dibutyltin dilaurate, dioctyltin dithioglycolate or dioctyltin mercaptide.

Preferably, the composition comprises a combination of two different amine catalysts or a combination of at least one amine and at least one alkyl tin catalyst. More preferably, the composition comprises a combination of two different amine catalysts. Even more preferably, the composition comprises at least one amine catalyst and at least one alkyl tin catalyst.

Preferably, the composition comprises a combination of 1-[bis[3-(dimethylamino)propyl]amino]-2-propanol and one other catalyst selected from diethyltoluenediamine and dioctyltin dithioglycolate. More preferably, the composition comprises a combination of diethyltoluenediamine and 1-[bis[3-(dimethylamino)propyl]amino]-2-propanol. Even more preferably, the composition comprises a combination of dioctyltin dithioglycolate and 1-[bis[3-(dimethylamino)propyl]amino]-2-propanol.

More preferably, the composition comprises diethyltoluenediamine, dioctyltin dithioglycolate, and 1-[bis[3-(dimethylamino)propyl]amino]-2-propanol.

At least two catalysts selected from amine catalysts and/or alkyl tin catalysts may be present in an amount of preferably up to 20 wt %, more preferably 0.5 wt % to 17 wt %, even more preferably 1 wt % to 15 wt %, based on the total weight of the polyurethane resin composition.

Preferably, the composition further comprises a co-catalyst and an additive. The co-catalyst is different from at least two catalysts selected from an amine catalyst and/or an alkyl tin catalyst. Suitable co-catalysts for the polyurethane resin composition are well known to those skilled in the art. For example, tertiary amines and phosphine compounds, metal catalysts such as chelates of various metals, acidic metal salts of strong acids; strong bases, alcoholates and phenolates of various metals, salts of organic acids and various metals, tetravalent tin, trivalent As and pentavalent As, organometallic derivatives of Sb and Bi, and metal carbonyl compounds of iron and cobalt and mixtures thereof can be used as catalysts.

Preferred tertiary amines are triethylamine, tributylamine, N-methylmorpholine, N-ethylmorpholine, N,N,N',N'-tetramethylethylenediamine, pentamethyl-diethylenetriamine and higher homologues (as in, for example, DE-A 2,624,527 and 2,624,528), 1,4-diazabicyclo(2.2.2)octane, N-methyl-N'-dimethyl-aminoethylpiperazine, bis-(dimethylaminoalkyl)piperazine, tris(dimethylaminopropyl)hexahydro-1,3,5-triazine, N,N-dimethylbenzylamine, N,N-dimethylcyclohexylamine, N,N-diethyl-benzylamine, bis-(N,N-diethylaminoethyl)adipate, N,N,N',N'-tetramethyl-1,3-butanediamine, N,N-dimethyl-p-phenylethylamine, 1,2-dimethylimidazole, 2-methylimidazole, monocyclic and bicyclic amines, and bis-(dialkylamino)alkyl ethers, such as 2,2-bis-(dimethylaminoethyl) ether. Triazine compounds, such as tris(dimethylaminopropyl)hexahydro-1,3,5-triazine, may also be used.

Preferred metal catalysts include metal salts and organometallic compounds including tin compounds, titanium compounds, zirconium compounds, hafnium compounds, bismuth compounds, zinc compounds, aluminum compounds and iron compounds, such as tin organic compounds, preferably alkyl tins, such as dimethyl tin or diethyl tin, or tin organic compounds based on aliphatic carboxylic acids, preferably tin diacetate, tin dilaurate, dibutyltin diacetate, dibutyltin dilaurate, bismuth compounds, such as alkyl bismuths or related compounds, or iron compounds, preferably iron (II) acetylacetonate or metal salts of carboxylic acids, such as tin-II isooctanoate, tin dioctoate, titanates or bismuth-(III) neodecanoate, or combinations thereof.

The auxiliary catalyst as described above may be present in an amount of preferably up to 20 wt %, based on the total weight of the polyurethane resin composition.

If present, additives may include one or more pigments, dyes, flame retardants, hindered amine light stabilizers, ultraviolet light absorbers, stabilizers, defoamers, internal mold release agents, desiccants, foaming agents and antistatic agents or combinations thereof. For more details about additives, see, for example, Kunststoffhandbuch, Volume 7, "Polyurethane" Carl-Hanser-Verlag Munich, 1st edition 1966, 2nd edition 1983 and 3rd edition 1993. Suitable amounts of these additives are well known to those skilled in the art. However, for example, based on the total weight of the polyurethane resin composition, the additives may be present in an amount preferably up to 20% by weight.

Preferably, the polyurethane resin composition as described above may further comprise a reinforcing agent. In the context of the present invention, a suitable reinforcing agent refers to a filler.

Suitable fillers include silicate minerals such as, for example, finely ground quartz, phyllosilicates such as antigorite, serpentine, hornblende, amphibole, chrysotile and talc, metal oxides such as kaolin, aluminum oxide, aluminum hydroxide, magnesium hydroxide, hydromagnesite, titanium oxide and iron oxide, metal salts such as chalk, barite and inorganic pigments such as cadmium sulfide, zinc sulfide, and glass, etc. Kaolin (china clay), finely ground quartz, aluminum silicate and coprecipitates of barium sulfate and aluminum silicate are preferably used.

Preferred for use as fillers are those having an average particle diameter in the range of ≥0.1 μm to ≤500 μm, or more preferably in the range of ≥1 μm to ≤100 μm or even more preferably in the range of ≥1 μm to ≤10 μm. In this context, in the case of non-spherical particles, the diameter refers to their extent along the shortest axis in space.

Suitable amounts of fillers may be present in the polyurethane resin composition, as known to those skilled in the art. For example, the filler may be present in an amount of up to 50 wt % based on the total weight of the polyurethane resin composition.

In another aspect, the presently claimed invention is directed to a polyurethane resin obtainable by a process comprising reacting: A. at least one isocyanate; and B. an isocyanate-reactive composition as described herein.

Preferably, the isocyanate comprises methylene diphenyl diisocyanate, polymeric methylene diphenyl diisocyanate, or a combination thereof. More preferably, the isocyanate is methylene diphenyl diisocyanate.

Preferably, the molar ratio of the sum of the functionalities of the isocyanate-reactive compositions used to the sum of the functionalities of the isocyanates used is in the range of 1:0.8 to 1:1.3. More preferably, the molar ratio of the sum of the functionalities of the isocyanate-reactive compositions used to the sum of the functionalities of the isocyanates used is in the range of 1:0.85 to 1:1.25, even more preferably 1:0.9 to 1:1.20.

Preferably, polyurethane resin is suitable for spray molding.Spray transfer molding or spray molding is such a method, in which atomized polyurethane particles are sprayed onto nonwoven material with high pressure nozzle or atomizer, then molded into required shape, rigidity, lightweight design are provided.In typical STM method, the first 60 seconds-90 seconds of the method are to use high pressure spray method to impregnate fabric outside the mold, and then molded in a compression press.Dry fiber or cushion are maintained by a programmable robot, and this programmable robot has optimized and controlled spray pattern.Then, use the high pressure nozzle head of atomized polyurethane resin to spray it.The cushion of impregnation is cured subsequently.

The resin of the present invention has a viscosity of ≤ 2000 cps at 23°C, thus making it very suitable for spray molding techniques. Preferably, the resin has a viscosity of ≤ 1800 cps at 23°C, even more preferably a viscosity of ≤ 1500 cps at 23°C.

Yet another aspect of the present invention relates to a panel construction comprising: A. at least one cushion layer; B. a polyurethane film prepared from a polyurethane resin composition which can be obtained by a method comprising reacting: a. at least one isocyanate, b. an isocyanate-reactive composition as described herein; C. a honeycomb layer adjacent to the cushion layer and in contact with the polyurethane film, wherein the polyurethane resin composition is sprayed onto at least one cushion layer to form the polyurethane film.

Preferably, in a panel construction as described above, no adhesive and/or fastening means are required to bond the polyurethane film to at least one cushioning layer. Advantages associated with the absence of adhesive and/or fastening means are the thickness of the control panel construction and faster and economical production of the panel construction.

Other advantages of panel construction are that they are mechanically stable, are seamless panels, can be in a variety of colors via the incorporation of pigments, are field repairable using automotive body techniques, have good thermal shock resistance, have high strength/low weight, are easy to handle and move, have reduced production steps, have high sound insulation, are weather and moisture resistant and are impermeable.

Preferably the panel construction has a thickness of preferably 0.5 mm to 30 mm, or 0.5 mm to 20 mm, or 0.5 mm to 10 mm.

Preferably, the mat layer as described above comprises non-woven fibers or fabric, a woven fabric or a non-crimped fabric. More preferably, the mat comprises non-woven fibers.

Preferably, the nonwoven fibers are natural fibers, synthetic fibers or glass fibers.

Preferably, the synthetic fibers are selected from carbon fibers or polyester fibers.

Preferably, the natural fibers are cellulosic bast fibers.

Preferably, the nonwoven fabric also contains a small amount of synthetic thermoplastic fibers, such as polyethylene terephthalate fibers (PET). The fibers may be synthetic polyester fibers or other fibers having similar properties.

More preferably, the cushion layer comprises nonwoven cellulose bast fibers, jute fibers, kenaf fibers, bamboo fibers, nonwoven polyester fibers, poly(methyl methacrylate), acrylonitrile-butadiene-styrene (ABS), polycarbonate, polypropylene, glass fibers, or a combination of two or more thereof. Even more preferably, the cushion layer comprises nonwoven cellulose bast fibers, nonwoven polyester fibers, poly(methyl methacrylate) (PMMA), acrylonitrile-butadiene-styrene (ABS), polycarbonate, polypropylene, or a combination of two or more thereof. The polyurethane resins as described herein are highly compatible for use with other plastics such as PMMA, polyester, polycarbonate, polypropylene, and ABS, and exhibit surprising adhesion behavior with said plastics (as can be seen in the Examples section below).

Preferably, the mat layer comprises glass fibers. The presence of glass fibers embedded in the panel construction significantly improves its dimensional stability while maintaining all other desired mechanical and processing properties. Suitable glass mat layers are well known to those skilled in the art. For example, chopped glass fibers and continuous glass fibers can be used for this purpose.

Preferably, the mat is obtained from chopped glass fibers. The chopped glass fibers can be obtained in shapes and sizes. For example, the chopped glass fibers can be fiber bundles such as having transverse and through-plane dimensions or spherical particles having a diameter. The present invention is not limited by the choice of shape and size of the chopped glass fibers, as those skilled in the art understand this choice. Preferably, the chopped glass fibers have a length of 10 mm to 150 mm, or 10 mm to 130 mm, or 10 mm to 100 mm.

Preferably, the honeycomb layer comprises at least one material selected from paperboard, polypropylene, recycled thermoplastics, polycarbonate or aluminum.

Although any suitable binder can be used to bind the chopped glass fibers, an acrylic binder is preferred. The acrylic binder is a water-based acrylic resin that is cured. The binder is cured, for example, by carboxyl groups and multifunctional alcohols.

Acrylic binders are polymers or copolymers containing acrylic acid units, methacrylic acid units, their esters or related derivatives. Acrylic binders are formed, for example, by aqueous emulsion polymerization using (meth)acrylic acid (wherein conventional (meth)acrylic acid is intended to include both acrylic acid and methacrylic acid), 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, amyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, pentyl (meth)acrylate, isoamyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate , undecyl (meth)acrylate, dodecyl (meth)acrylate, lauryl (meth)acrylate, octadecyl (meth)acrylate, octadecyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, butoxyethyl (meth)acrylate, ethoxydiglycol (meth)acrylate, benzyl (meth)acrylate, cyclohexyl (meth)acrylate, phenoxyethyl (meth)acrylate, polyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, methoxyethylene glycol (meth)acrylate, carbitol (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, methoxypolypropylene glycol (meth)acrylate, dicyclopentadienyl (meth)acrylate, dicyclopentanyl (meth)acrylate, tricyclodecyl (meth)acrylate, isobornyl (meth)acrylate, bornyl (meth)acrylate, or a mixture thereof.

Other monomers (usually in small amounts) that can be copolymerized with the (meth) acrylic monomer include styrene, diacetone (meth) acrylamide, isobutoxymethyl (meth) acrylamide, N-vinyl pyrrolidone, N-vinyl caprolactam, N,N-dimethyl (meth) acrylamide, tert-octyl (meth) acrylamide, N,N-diethyl (meth) acrylamide, N,N'-dimethyl-aminopropyl (meth) acrylamide, (meth) acryloyl morpholine; vinyl ethers such as hydroxybutyl vinyl ether, lauryl vinyl ether, cetyl vinyl ether and 2-ethylhexyl vinyl ether; maleates; fumarates and similar compounds. The choice and amount of the monomer can affect the adhesion of the PU to the cushion layer.

The polyfunctional alcohol is, for example, hydroquinone, 4,4′-dihydroxydiphenyl, 2,2-bis(4-hydroxyphenyl)propane, cresol or an alkylene polyol containing 2 to 12 carbon atoms, including ethylene glycol, 1,2-propylene glycol or 1,3-propylene glycol, 1,2-butylene glycol, 1,3-butylene glycol or 1,4-butylene glycol, pentanediol, hexanediol, octanediol, dodecanediol, diethylene glycol, triethylene glycol, 1,3-cyclopentanediol, 1,2-cyclohexanediol, 1,3-cyclohexanediol or 1,4-cyclohexanediol, 1,4-dihydroxymethylcyclohexane, glycerol, tri(β-hydroxyethyl)amine, trimethylolethane, trimethylolpropane, pentaerythritol, dipentaerythritol, tripentaerythritol and sorbitol.

Water-based acrylic adhesives are available from BASF under the name Commercially available.

Preferably, a water-based acrylic resin is injected into the mat. That is, the mat is impregnated with the acrylic resin. The mat is compressed and cured with heat and pressure. Pressure is not required for curing, but is required for setting the desired thickness or density or shape. Forming is performed, for example, in a heated forming tool to the desired shape.

The water-based acrylic binder can be applied to the nonwoven fibers or fabrics by a dipping and extrusion process, a curtain coater or a foam injection process.Before heat curing, the mixture is dried to a low moisture content, preferably in an amount of 4 to 7 wt%.

During the initial heating and compression, the compression release allows the water to be discharged. The number of releases depends on the amount of water contained in the uncured mat. The cured mat does not contain a significant amount of water. Preferably, the amount of water is 0 wt % to 3 wt % or by dry weight of the mat layer.

Once cured, the mat does not swell significantly. Preferred mat basis weights are from 100 grams per square meter (gsm) to 1400 grams per square meter. The loading of acrylic resin is preferably from 15% to 50% or from 20% to 40% by weight of the dried resin based on the finished mat weight.

Preferably, if the mat comprises continuous glass fibers, the use of a binder as described above can be avoided. The present invention is not limited by the choice of shape and size of the continuous glass fibers, as those skilled in the art understand the choice. The continuous glass fibers can be oriented in one direction or in several directions, such as transverse orientation, vertical orientation, or any angle orientation between transverse and vertical. The mat comprising continuous glass fibers has a nominal weight preferably of 100 g/m ² to 1000 g/m ² .

The mat layer as described above preferably has an area weight of preferably 100 g/m ² to 1500 g/m ² and a thickness of preferably 0.5 mm to 30 mm. Suitable techniques for measuring area weight and thickness are well known to those skilled in the art.

Preferably, the panel construction includes more than one mat layer, for example two mat layers, three mat layers, four mat layers or five mat layers to form a multi-layer system. In such cases, the mats can be the same or different. They can have the same basis weight or thickness or have different basis weights or thicknesses. In addition, the fibers used in the multi-layer system can be the same or different. The selection and choice of the number of layers and their mats is well known to those skilled in the art.

Preferably, the mat layer may be a hybrid layer comprising at least one layer of chopped glass fibers and at least one layer of continuous glass fibers. Preferably, it may also contain a film or a scrim to enhance the surface quality. The film or scrim may be inserted on top of the hybrid layer.

Preferably, the panel construction is an integral composite material (also referred to as an integral panel construction) comprising a single cushion layer and a polyurethane film as described above. The polyurethane film is prepared by spraying a polyurethane resin composition onto the cushion layer. In the context of the present invention, the term "polyurethane film" refers to an atomized polyurethane resin composition that adheres to the cushion layer when sprayed onto the cushion layer and has no thickness itself. That is, the polyurethane film does not exist on the cushion layer as a separate layer. In addition, the term "atomized" refers to particles or droplets of a polyurethane resin composition obtained from a suitable spraying device (such as, but not limited to, a nozzle or an atomizer).

Preferably, the polyurethane resin composition is sprayed onto at least one cushion layer in an amount of 450 gsm to 1500 gsm, more preferably 450 gsm to 1200 gsm, even more preferably 450 gsm to 1000 gsm, most preferably 450 gsm to 900 gsm.

In another preferred embodiment, the overall composite material may further comprise additional materials disposed on the overall composite material using suitable techniques known to those skilled in the art. These additional materials may be, for example, polyisocyanate addition products. The term "polyisocyanate addition product" refers to the reaction product of a suitable amount of a polyisocyanate and a compound reactive to isocyanate, preferably having a molecular weight of 500 g/mol or more.

Polyisocyanate addition polymerization products include cellular polyurethane elastomers and flexible polyurethane foams, semi-rigid polyurethane foams or rigid polyurethane foams. In an exemplary embodiment, polyisocyanate addition polymerization products such as polyurethane-urea, open polyurethane foams and closed polyurethane foams are arranged on the overall panel structure. For example, polyisocyanate addition polymerization products can be used as an additional layer to be arranged or sprayed or impregnated on the overall panel structure. The addition of these polyisocyanate addition polymerization products further enhances the mechanical properties of the overall panel structure and enhances the applicability such as used in the automotive industry.

Preferably, the isocyanate comprises methylene diphenyl diisocyanate, polymeric methylene diphenyl diisocyanate, or a combination thereof. More preferably, the isocyanate is methylene diphenyl diisocyanate.

The polyurethane film as described above is prepared from a polyurethane resin composition which can be obtained by a method comprising reacting:

(a) at least one isocyanate, and

(b) an isocyanate-reactive composition as described herein.

Typically, the isocyanates may be present in monomeric form, polymeric form or as a mixture of monomeric and polymeric forms. The term "polymeric" refers to a polymeric grade of aliphatic isocyanates, aromatic isocyanates or mixtures thereof comprising dimers, trimers, higher homologs and/or oligomers.

The term "aromatic isocyanate" refers to a molecule having two or more isocyanate groups attached directly and/or indirectly to an aromatic ring. Preferably, the isocyanate is an aromatic isocyanate selected from toluene diisocyanate; polymeric toluene diisocyanate, methylene diphenyl diisocyanate (or monomeric MDI); polymeric methylene diphenyl diisocyanate; meta-phenylene diisocyanate; 1,5-naphthalene diisocyanate; 4-chloro-1,3-phenylene diisocyanate; 2,4,6-toluene triisocyanate, 1,3-diisopropylphenylene-2,4-diisocyanate; 1-methyl-3,5-diethylphenylene-2,4-diisocyanate; 1,3,5-triethylphenylene-2,4-diisocyanate; 1,3,5-triisopropyl-phenylene-2,4-diisocyanate; Phenyl-2,4-diisocyanate; 3,3'-diethyl-diphenyl-4,4'-diisocyanate; 3,5,3',5'-tetraethyl-diphenylmethane-4,4'-diisocyanate; 3,5,3',5'-tetraisopropyldiphenylmethane-4,4'-diisocyanate; 1-ethyl-4-ethoxy-phenyl-2,5-diisocyanate; 1,3,5-triethylbenzene-2,4,6-triisocyanate; 1-ethyl-3,5-diisopropylbenzene-2,4,6-triisocyanate, tolidine diisocyanate, 1,3,5-triisopropylbenzene-2,4,6-triisocyanate or a mixture thereof. More preferably, the aromatic isocyanate is selected from toluene diisocyanate; polymerized toluene diisocyanate, methylene diphenyl diisocyanate; polymerized methylene diphenyl diisocyanate, meta-phenylene diisocyanate; 1,5-naphthalene diisocyanate; 4-chloro-1,3-phenylene diisocyanate; 2,4,6-toluene triisocyanate, 1,3-diisopropylphenylene-2,4-diisocyanate and 1-methyl-3,5-diethylphenylene-2,4-diisocyanate or mixtures thereof. Even more preferably, the aromatic isocyanate is selected from toluene diisocyanate; polymerized toluene diisocyanate, methylene diphenyl diisocyanate; polymerized methylene diphenyl diisocyanate, meta-phenylene diisocyanate or 1,5-naphthalene diisocyanate or mixtures thereof. Still more preferably, the aromatic isocyanate is selected from toluene diisocyanate; polymeric toluene diisocyanate, methylene diphenyl diisocyanate, polymeric methylene diphenyl diisocyanate or mixtures thereof. More preferably, the isocyanate is methylene diphenyl diisocyanate or polymeric methylene diphenyl diisocyanate.

Preferably, the aromatic isocyanate is monomeric MDI and/or polymeric MDI.

Preferably, the aromatic isocyanate is monomeric MDI. More preferably, the monomeric MDI is selected from 4,4'-MDI, 2,2'-MDI and 2,4'-MDI, or a combination of two or more thereof.

Preferably, the aromatic isocyanate is polymeric MDI.Commercially available isocyanates available from BASF under trade names such as Lupranat may also be used for the purposes of the present invention.

More preferably, the polymeric MDI comprises different amounts of isomers, such as 4,4'-MDI, 2,2'-MDI and 2,4'-MDI. The amount of 4,4'MDI isomer is preferably 26 to 98 wt%, or more preferably 30 to 95 wt%, or even more preferably 30 to 80 wt%, relative to the isomers, with the remainder being the oligomeric species. Methylene diphenyl diisocyanate isomers are typically a mixture of 4,4'-methylene diphenyl diisocyanate, 2,4'-methylene diphenyl diisocyanate and very low levels of 2,2'-methylene diphenyl diisocyanate.

From the context of the present invention, the purity of the polymeric MDI or pMDI is not important. Preferably, the pMDI used according to the present invention has an iron content of 1 ppm to 100 ppm, or 1 ppm to 70 ppm, or 1 ppm to 80 ppm, or 1 ppm to 60 ppm, based on the total amount of pMDI.

Preferably, the pMDI has an NCO content in the range of 22 to 40 wt%, or 25 to 37 wt%, or 28 to 35 wt%, or 30 to 33 wt%, based on the total weight of the pMDI.

Polymeric methylene diphenyl diisocyanate tends to have an isocyanate functionality above 2. Preferably, pMDI has a functionality of at least 2.3, or at least 2.5, or at least 2.7. More preferably, pMDI has a functionality in the range of 2.3 to 4.5, or 2.5 to 4.3, or 2.5 to 4.0.

In addition, polymeric isocyanates include reaction products of polyisocyanates and polyols, and mixtures thereof with other diisocyanates and polyisocyanates may also be used.

Preferably, the isocyanates have an average functionality of at least 2.0, or from 2.0 to 3.0. The isocyanates preferably comprise aliphatic isocyanates or aromatic isocyanates or combinations thereof.

Preferably, the amount of isocyanate in the polyurethane resin is such that the isocyanate index is preferably from 70 to 350, or from 80 to 300, or from 90 to 200, or from 100 to 150. An isocyanate index of 100 corresponds to one isocyanate group per one isocyanate-reactive group.

In another aspect, the presently claimed invention relates to a method for preparing a panel construction, the method comprising the following steps: (S1) spraying a polyurethane resin composition onto at least one surface of a cushion layer, wherein the polyurethane resin composition can be obtained by a method comprising reacting the following substances: a. an isocyanate, b. an isocyanate-reactive composition as described herein, wherein the polyurethane resin composition forms a polyurethane film on at least one surface of the cushion layer; and obtaining a pre-impregnated blank, and (S2) compression molding the pre-impregnated blank together with a honeycomb layer.

The polyurethane resin composition, isocyanate, isocyanate-reactive compound, catalyst, additives and filler used in the process according to the invention are described above.

Preferably, the above method is a spray transfer molding method.

In step (S1), the spraying of the polyurethane resin composition obtained by a method comprising reacting an isocyanate with a compound reactive to isocyanate refers to a two-component system comprising an isocyanate component and a component comprising a compound reactive to isocyanate. Preferably, the two-component system comprises an isocyanate component and a polyol component comprising at least one polyether polyol having an average functionality of 2.0 to 4.0. The term "component" refers to a mixture comprising an isocyanate and a catalyst, an additive and a filler and a polyol as described above. The presence of catalysts, additives and fillers in the polyol component and/or the isocyanate component depends on the desired properties of the final polyurethane resin composition. In an exemplary embodiment, the polyol component may include a polyol, a catalyst, an additive and a filler, while the isocyanate component is mainly composed of an isocyanate as described above.

In addition, multi-component systems comprising more than two components may also be employed. For example, in addition to the conventionally used polyol component and isocyanate component, at least one additional component may also be present. Suitable compounds for the additional components may include compounds reactive to isocyanates, isocyanates, catalysts, additives, fillers and mixtures thereof. More preferably, at least one additional component is different from the polyol component and the isocyanate component.

In step (S1), the polyurethane resin composition is sprayed onto at least one cushion layer using suitable means well known to those skilled in the art (see Ullman's Encyclopedia of Industrial Chemistry; DOI: 10.1002/14356007). However, the isocyanate and the component reactive to the isocyanate can be mixed in a mixing device to obtain a reactive mixture, which is then sprayed onto at least one cushion layer as a polyurethane composition to obtain a pre-impregnated blank. Suitable mixing devices for this purpose are preferably mixing heads or static mixers.

In an exemplary embodiment, the reaction mixture is obtained by feeding at least two streams into a mixing device, wherein:

(i) the first stream comprises at least one isocyanate component, and

(ii) the second stream comprises at least one polyol component,

At least two catalysts, additives and optionally fillers are present in at least one of (i) and (ii).

Suitable temperatures for processing the reaction mixture are well known to the person skilled in the art.In a preferred embodiment, the first stream and the second stream can be premixed independently of one another in a suitable mixing device, such as a static mixer.

The mixing device may be a low-pressure mixing device or a high-pressure mixing device, wherein the low-pressure mixing device or the high-pressure mixing device comprises:

- a pump which feeds the material flow,

a high-pressure mixing head in which the streams as described above are mixed,

a first feed line, which is installed on the high-pressure mixing head and through which the first stream is introduced into the mixing head, and

a second feed line, which is installed on the high-pressure mixing head and through which the second stream is introduced into the mixing head,

Optionally, the mixing device as described above may further comprise at least one measuring and control unit for establishing the pressure of each feed line in the mixing head. In addition, the term "low pressure" herein refers to a pressure of 0.1 MPa to 5 MPa, while the term "high pressure" refers to a pressure above 5 MPa.

Preferably, the reaction mixture is introduced from the mixing head into the mixing device. The solid/gas mixture can be added via an additional inlet. "Solid" refers to a filler as described above, which is a substance in a solid state.

The reaction mixture obtained from the mixing device is fed to a spray device. Suitable spray devices include, but are not limited to, spray heads. In a preferred embodiment, the spray head for spraying the polyurethane resin composition comprises at least one polyurethane spray jet. The polyurethane spray jet is essentially composed of fine particles or droplets of the polyurethane resin composition (i.e., the reaction mixture), which are preferably dispersed in an airflow. Such polyurethane spray jets can be obtained in different ways, for example, by atomizing a liquid jet of the reaction mixture of the polyurethane resin composition via an airflow introduced therein or by spraying a liquid jet of the reaction mixture from a corresponding nozzle or atomizer. The term "liquid jet of the reaction mixture" refers to a fluid jet of the reaction mixture of the polyurethane resin composition, which is not yet in the form of fine reaction mixture droplets dispersed in an airflow, i.e., in particular in a liquid viscous phase. Therefore, in particular, such "liquid jet of the reaction mixture" does not mean a polyurethane spray jet as described above. Such processes are described, for example, in DE 10 2005 048 874 A1, DE 101 61600 A1, WO 2007/073825 A2, US 3,107,057 A and DE 1 202 977 B, all of which are incorporated herein by reference.

Alternatively, a solid-containing airflow can also be used to replace the airflow as described above. The solid-containing airflow is preferably prepared by passing the airflow through the solid-containing metering unit of the honeycomb wheel gate. By flushing the honeycomb space, the solid is dragged by the pressurized air flow and delivered to the mixing head as a solid/air or solid/gas mixture. In order to avoid pulsation, the channel in the metering gate must be designed to have a diameter that excludes positive overlap. This embodiment further ensures that even when the honeycomb wheel gate metering is closed and its revolutions per minute change, a quantitatively constant air flow rate for spraying the reaction mixture is also available, and therefore the spraying can be carried out alternately without or with a variable filler amount. As a special advantage of this type of honeycomb wheel gate, the solid proportion in the prepreg to be prepared can be variably adjusted.

The polyurethane spray jet as described above impinges on a spray area which oscillates with an adjustable amplitude of preferably less than 500 mm.The term "spray area" refers to a target area of at least one cushion layer.

During the spraying as disclosed above, the at least one mat layer is preferably wetted on both sides with the polyurethane resin composition likewise described above. It is particularly preferred that the spraying of the polyurethane resin composition is carried out on both sides of the at least one mat layer.

The processing of at least one cushion can be carried out manually or automatically. The term "automatically" refers to the processing of at least one cushion, for example, using an industrial robot via a human-machine interface. In a preferred embodiment, an industrial robot is adopted, which preferably has 6 axes and is particularly suitable for production facilities automated using a flexible robot controller. The robot is operated by means of process software incorporated into a control cabinet. The controller (control) is suitable for communicating with an external control system. The robot can be equipped with a highly developed dual-port safety system, the function of which is continuously monitored. In the case of failure or malfunction, the power supply of the motor can be cut off and the brake can be activated. In addition, the movement of each axis can be limited by a software function. In a preferred embodiment, the robot is driven via a brushless three-phase servo motor with a brake on all axes.

The pre-impregnated blank obtained in step (S1) is then compression molded in step (S2), for example in a heated compression molding tool, and is compressed and hardened according to the required panel construction geometry. Subsequently, when the panel construction remains in the compression molding tool, contour cutting, that is, rough cutting to shape, can optionally be performed around the tool or around the tool geometry.

Preferably, if necessary, the panel construction can also be cooled or thermally stabilized in the compression molding tool or outside the compression molding tool, more preferably in a further tool, in particular a workpiece cooling device.

According to an embodiment, "thermally stable" is understood to mean that the panel construction assumes a temperature below the previous transformation temperature in order to obtain a stable state. In this context, cooling in a workpiece cooling device enables a minimum production time, in particular for a continuous production of only one panel construction.

Preferably, in order to compensate for deformations and/or to increase the crosslinking level of the material, tempering, i.e. temperature progression, of the panel construction is carried out in a further tool or in a further device. For example, it can be provided that for cooling, the panel construction is placed only on a frame or on a surface by one side. However, it is also possible to use a closed cooling device which surrounds the panel construction around the entire circumference and in which the temperature can be adjusted. Further cooling of the panel construction can optionally be carried out.

Preferably, after cooling the outer contour can be trimmed according to the required panel construction contour, or cut into the shape of the side areas/edges, and optionally chip-removing machining processes can also be carried out, such as, for example, milling the outer contour and milling and drilling inserts and other similar recesses in the panel construction.

In another aspect, the presently claimed invention relates to the use of a panel construction as described herein or as obtained by a method as described herein as an automotive component.

In yet another aspect, the presently claimed invention relates to an automotive component comprising a panel construction as described herein or as obtained by a method as described herein.

Preferred automotive parts include lower soundproofing hoods, acoustic belly pans, aero hoods, splash shields, underbody panels, chassis covers, door modules, trunk lids or leaf springs.

The method according to the invention is explained in more detail by means of the accompanying drawings.

Figure 1 shows the sandwich structure of the final assembly, which consists of: Layer 1: thermoplastic sheet such as PMMA; Layer 2 and Layer 4: cushion layer impregnated with polyurethane by spraying polyurethane mixture; Layer 3: honeycomb made of cardboard or thermoplastic or metal; Layer 5: optional thermoplastic sheet such as PMMA.

Figure 2 shows the peel force-displacement of an inventive example (IE1). The figure shows a typical peel force measured during cohesive delamination of a thermoplastic sheet from a honeycomb composite.

The composition according to the presently claimed invention has at least one of the following advantages:

1. The isocyanate-reactive composition of the presently claimed invention has low viscosity (≤ 2000 cps at 23°C) and high lubricity.

2. The isocyanate-reactive composition of the presently claimed invention has a high castor oil content, which results in a composition that is less toxic and environmentally friendly.

3. The polyurethane resin of the presently claimed invention has high adhesion/bonding to thermoplastics and ensures greater wettability of the mat layer.

4. The polyurethane resin of the presently claimed invention is suitable for spray molding techniques.

The invention is explained in more detail by the following embodiments and combinations of embodiments resulting from reference and association of the corresponding dependent terms:

1. An isocyanate-reactive composition for making a polyurethane resin, the composition comprising:

A. Castor oil

B. At least one polyether polyol having an average functionality of 2.0 to 4.0

C. At least one chain extender

D. At least two catalysts selected from amine catalysts and/or alkyl tin catalysts.

II. The composition according to any one of embodiments I, wherein the weight ratio of polyether polyol to castor oil is in the range of 0.5 to 6.0.

III. The composition according to embodiments I to II, wherein the castor oil content is in the range of 25% to 60% by weight relative to the total weight of the composition.

IV. The composition according to any one of embodiments I to III, wherein the at least one polyether polyol has a hydroxyl value as determined by DIN 53240 of 15 mg KOH/g to 1800 mg KOH/g.

V. The composition according to any one of embodiments I to IV, wherein the at least one polyether polyol content is in the range of 35% to 65% by weight relative to the total weight of the composition.

VI. The composition according to any one of embodiments I to V, wherein the at least one chain extender is present in an amount ranging from 1% to 15% by weight relative to the total weight of the composition.

VII. A composition according to any one of embodiments I to VI, wherein the at least two catalysts are selected from diethyltoluenediamine, dioctyltin dithioglycolate or 1-[bis(2-[(2- ...

[3-(Dimethylamino)propyl]amino]-2-propanol.

VIII. The composition of any one of embodiments I to VII, wherein the composition comprises diethyltoluenediamine, dioctyltin dithioglycolate, and 1-[bis[3-(dimethylamino)propyl]amino]-2-propanol.

IX. A polyurethane resin obtainable by a method comprising reacting:

A. isocyanates; and

B. An isocyanate-reactive composition according to any one of embodiments I to VIII.

X. The polyurethane resin according to embodiment IX, wherein the isocyanate comprises methylene diphenyl diisocyanate, polymerized methylene diphenyl diisocyanate, or a combination thereof.

XI. The polyurethane resin according to any one of embodiments IX to X, wherein the molar ratio of the sum of functionalities of the isocyanate-reactive composition used to the sum of functionalities of the isocyanate used is in the range of 1:0.8 to 1:1.3. XII. The polyurethane resin according to any one of embodiments IX to XI, wherein the resin is suitable for spray molding.

XIII. A panel structure, comprising:

(A) At least one cushion

(B) a polyurethane film, the polyurethane film being prepared from a polyurethane resin composition obtainable by a method comprising reacting:

(a) isocyanate, and

(b) an isocyanate-reactive composition according to any one of embodiments I to VIII,

(C) a honeycomb layer, the honeycomb layer being adjacent to the cushion layer and in contact with the polyurethane film,

The polyurethane resin composition is sprayed onto the at least one cushion layer to form the polyurethane film.

XIV. A panel construction according to embodiment XIII, wherein the mat layer comprises non-woven cellulose bast fibers, non-woven polyester fibers, poly(methyl methacrylate), acrylonitrile-butadiene-styrene (ABS), polycarbonate, polypropylene, glass fibers, or combinations thereof.

XV. The panel construction of any one of embodiments XIII to XIV, wherein the isocyanate comprises methylene diphenyl diisocyanate, polymeric methylene diphenyl diisocyanate, or a combination thereof.

XVI. A method for preparing a panel construction, the method comprising the steps of:

(S1) spraying a polyurethane resin composition onto at least one surface of the cushion layer, wherein

The polyurethane resin composition can be obtained by a method comprising reacting the following substances:

(a) isocyanate, and

(b) an isocyanate-reactive composition according to any one of Embodiments I to VIII; and

wherein the polyurethane resin composition forms a polyurethane film on at least one surface of the cushion layer;

And obtain a pre-impregnated green body,

as well as

(S2) compression molding the prepreg body together with a honeycomb layer.

XVII. The method according to embodiment XVI, wherein the polyurethane resin composition is atomized.

XVIII. The method according to any one of embodiments XVI to XVII, wherein the method is a spray transfer molding method.

XIX. Use of the panel construction according to any one of embodiments XIII to XV or as obtained by the process according to any one of embodiments XVI to XVIII as an automotive component.

XX. The use according to embodiment XIX, wherein the automotive part comprises a lower sound shield, an acoustic belly pan, an aero shield, a splash shield, an underbody panel, a chassis cover, a door module, a rear luggage rack, or a leaf spring.

XXI. An automotive component comprising a panel construction according to any one of embodiments XIII to XV or as obtained by a method according to any one of embodiments XVI to XVIII.

EXAMPLES The presently claimed invention is illustrated by the following non-limiting examples:

Raw materials

Standard Methods

The peel test is performed similarly to the posi test, but is modified based on the average of (peel force [lbf])/(length [in]. For the peel test, the sample is cut into 2 inches wide and 6 inches long. The thermoplastic is then peeled using a universal tensile testing machine and the peel force is measured. The peel force obtained is an indication of the adhesion between the thermoplastic and the composite.

General synthesis of mixtures for producing PU foams

The above raw materials are added to the A-side component and the B-side component in the amounts mentioned in Table 1 (all in wt %). Both the A-side component and the B-side component are then added to a mixing device such as a static mixer of a spray device or other mixing methods such as a mixing cup to obtain the desired mixing level. For example, the mixture is mixed at 3000 rpm and the temperature of the A-side component and the B-side component is maintained at 25° C. to 30° C. IE 1 represents a polyurethane resin obtained with the isocyanate-reactive composition of the present invention, while CE 1 represents a resin developed by comparison. The isocyanate-reactive composition of CE 1 does not contain castor oil.

The PU foams thus obtained were subsequently processed for testing and the properties determined.

Table 1 :

The isocyanate reactive compositions of the present invention produce low viscosity compositions (≤2000 cps at 23°C) suitable for easy processing. It is noted that the resulting polyurethane resin obtained by reacting the isocyanate reactive composition leads to a surprising improvement in adhesion to thermoplastic adhesives. This is clearly identified by the high peel force values shown in Table 1. The surprisingly high peel force displacement can be clearly identified in Figure 2. It is noted from the figure that the peel force range is high enough to prevent future delamination. The significantly high peel force required to displace the polyurethane film from the thermoplastic cushion layer clearly indicates high adhesion to thermoplastics. Several comparative systems (e.g., CE 1) were compared, and it was found that the peel force was significantly lower. In addition, the resin shows a strong bond with PMMA/PC.

Claims (21)

1. An isocyanate-reactive composition for use in the manufacture of polyurethane resins, the composition comprising:

A. Castor oil

B. at least one polyether polyol having an average functionality of 2.0 to 4.0

C. At least one chain extender

D. at least two catalysts selected from amine catalysts and/or alkyl tin catalysts.

2. The composition of any one of claims 1 to 5, wherein the weight ratio of the at least one polyether polyol to castor oil is in the range of 0.5 to 6.0.

3. The composition according to claims 1 to 2, wherein the castor oil content is in the range of 25 to 60 wt% relative to the total weight of the composition.

4. A composition according to any one of claims 1 to 3, wherein the at least one polyether polyol has a hydroxyl number of from 15mg KOH/g to 1800mg KOH/g as determined by DIN 53240.

5. The composition of any one of claims 1 to 4, wherein the at least one polyether polyol content is in the range of 35 to 65 wt% relative to the total weight of the composition.

6. The composition according to any one of claims 1 to 5, wherein the at least one chain extender content is in the range of 1 to 15 wt% relative to the total weight of the composition.

7. The composition of any one of claims 1 to 6, wherein the composition comprises diethyltoluenediamine, dioctyltin dithioglycolate, and 1- [ bis [3- (dimethylamino) propyl ] amino ] -2-propanol.

8. The composition of any one of claims 1 to 7, wherein the at least one chain extender is different from the at least one polyether polyol.

9. A polyurethane resin obtainable by a process comprising reacting:

C. An isocyanate; and

D. The isocyanate-reactive composition according to any one of claims 1 to 8.

10. The polyurethane resin of claim 8, wherein the isocyanate is selected from methylene diphenyl diisocyanate, polymeric methylene diphenyl diisocyanate, or a combination thereof.

11. The polyurethane resin according to any one of claims 9 to 10, wherein the molar ratio of the sum of the functionalities of the isocyanate-reactive composition used to the sum of the functionalities of the isocyanate used is in the range of 1:0.8 to 1:1.3.

12. The polyurethane resin according to any one of claims 9 to 11, wherein the resin is suitable for spray molding.

13. A panel construction, the panel construction comprising:

(A) At least one cushion layer, and

(B) A polyurethane film prepared from a polyurethane resin composition obtainable by a process comprising reacting:

(a) Isocyanate, and

(B) The isocyanate-reactive composition according to any one of claim 1 to 8,

(C) A honeycomb layer adjacent to the cushion layer and in contact with the polyurethane film,

Wherein the polyurethane resin composition is sprayed onto the at least one cushion layer to form the polyurethane film.

14. The panel construction of claim 13, wherein the cushion layer comprises nonwoven cellulosic bast fibers, nonwoven polyester fibers, poly (methyl methacrylate), acrylonitrile Butadiene Styrene (ABS), polycarbonate, polypropylene, fiberglass, or a combination thereof.

15. The panel construction of any one of claims 13 to 14, wherein the isocyanate comprises methylene diphenyl diisocyanate, polymeric methylene diphenyl diisocyanate, or a combination thereof.

16. A method for preparing a panel construction, the method comprising the steps of:

(S1) spraying a polyurethane resin composition onto at least one surface of the mat layer, wherein the polyurethane resin composition is obtainable by a process comprising reacting:

(a) Isocyanate, and

(B) The isocyanate-reactive composition according to any one of claims 1 to 8; and

Wherein the polyurethane resin composition forms a polyurethane film on the at least one surface of the cushion layer;

And a pre-impregnated blank is obtained which,

And

(S2) compression molding the pre-impregnated blank with a honeycomb layer.

17. The method according to claim 16, wherein the polyurethane resin composition is atomized in step (S1).

18. The method of claim 16 or 17, wherein the method is a spray transfer molding method.

19. Use of a panel construction according to any one of claims 13 to 15 or as obtained by a method according to any one of claims 16 to 18 as an automotive component.

20. The use of claim 19, wherein the automotive component further comprises a lower sound shield, an acoustic belly pan, an aircraft shield, a splash shield, an underbody panel, a chassis shield, a door module, a rear luggage rack, or a leaf spring.

21. An automotive part comprising a panel construction according to any one of claims 13 to 14 or as obtained by the method according to any one of claims 16 to 18.