Fiber Reinforced Polyurethane Composite Material, Its Preparation Method and Application

Abstract

The present invention relates to the field of composite materials, and particularly to a fiber-reinforced polyurethane composite material and a preparation method thereof. The composite material contains rigid polyurethane foam and reinforcing fibers, and the material density is 300-500 Kg / m<supgt;3< / supgt>; the water absorption rate of the composite material is ≤5%, the Shore hardness is ≥60 HA, the flexural strength is ≥50 Mpa, the shear strength is ≥10 Mpa, the dimensional stability is ≤1%, the appearance remains unchanged after being soaked in acid solution or alkali solution for 30 days, the thermal conductivity is ≤0.05 W / (m·K), and the linear thermal expansion coefficient (1 / °C) is ≤1×10<supgt;‑5< / supgt>. This composite material combines light weight and high strength, mechanical properties (such as shear resistance and compressive resistance), heat insulation, acid and alkali resistance, anti-corrosion and moisture-proof, and good dimensional stability, and can be used in low-density materials (non-structural materials) such as doors and windows, filling, and exterior decoration.

Description

Technical Field

[0001] The present invention relates to the field of composite materials, and specifically relates to a fiber-reinforced polyurethane composite material and a preparation method thereof. Background Art

[0002] Natural wood is widely used in various aspects such as construction, furniture, and outdoor products due to its ecological environmental protection, suitable elasticity and hardness, and good performance. Considering the poor natural anti-corrosion property of fast-growing wood, before its use, it is usually subjected to anti-corrosion treatment. No matter what anti-corrosion impregnation treatment method is adopted for such anti-corrosion wood, the preservative enters the wood from the outside, so the preservative loading amount in the outer layer of the anti-corrosion wood is the highest, and the closer to the core layer, the lower the preservative loading amount. For wood with a high loading amount of preservative, the leaching property of the agent is also greater. Therefore, for the anti-corrosion wood impregnated with the preservative solution, with the prolongation of the use time, affected by frequent temperature changes, ultraviolet radiation, and atmospheric humidity, it will have a rapid destructive effect on the anti-corrosion wood. The preservative in the outer layer in contact with the environment gradually loses, and its durability gradually decreases, such as water absorption and deformation, cracking, mildew, insect infestation, rot, etc. The duration of the durability of the anti-corrosion wood is difficult to meet the actual engineering use requirements. If maintenance or replacement is required, a large amount of wood will be consumed, resulting in the destruction of forest resources in the long term, and at the same time, a large amount of maintenance personnel will also be consumed.

[0003] This year, the country has elevated carbon neutrality and carbon peak to a national strategy, putting forward higher requirements for energy conservation and environmental protection. Therefore, it has become an urgent task to find a new material with low cost, mechanical properties equivalent to or even higher than those of solid wood, anti-corrosion and moisture resistance properties higher than those of existing anti-corrosion wood, and safe, non-toxic and environmentally friendly. Summary of the Invention

[0004] The present invention aims to provide a fiber-reinforced polyurethane composite material with low water absorption, good mechanical properties, acid and alkali corrosion resistance, and high dimensional stability.

[0005] To achieve the above object, the present invention adopts the following technical scheme: The composite material contains rigid polyurethane foam and reinforcing fibers, and the material density is 300 - 500 Kg / m 3 ; the water absorption rate of the composite material is ≤5%, the Shore hardness is ≥60 HA, the flexural strength is ≥50 Mpa, the shear strength is ≥10 Mpa, the dimensional stability is ≤1.5%, the appearance remains unchanged after soaking in acid solution or alkali solution for 30 days, the thermal conductivity is ≤0.05 W / (m·K), and the linear thermal expansion coefficient (1 / ℃) is ≤1.0×10 -5 .

[0006] The advantages of this composite material are as follows:

[0007] (1) In terms of material density, the density of this composite material is 300 - 500 Kg / m3 , its density is equivalent to or even lower than that of poplar and pine (about 400 Kg / m³), and is close to the density of natural linden (500 - 550 Kg / m 3 ). Therefore, it can be processed by methods such as shaving, sawing, and planing like natural solid wood; in terms of water absorption rate, the water absorption rate of the composite material ≤ 5%, which is lower than that of solid wood materials, and the performance is more excellent;

[0008] (2) In terms of heat preservation and insulation, the thermal conductivity coefficient of this composite material ≤ 0.05 W / (m·K), and the thermal conductivity is low. Compared with natural dry solid wood (thermal conductivity coefficient ≥ 0.08 W / (m·K)), its heat insulation and preservation performance is higher, and it can be used as a heat preservation material for walls and door and window core materials with higher requirements for heat preservation and insulation;

[0009] (3) The mechanical properties of this composite material have been greatly improved compared with natural wood (or natural wood treated with anti-corrosion, that is, anti-corrosion wood). Its shear resistance, bending resistance, etc. are higher than those of natural wood, with higher hardness, and it has the characteristics of light weight and high strength. Even when exposed to the air for a long time, it will not lose its mechanical properties. Therefore, in terms of mechanical properties, it can completely replace natural wood (anti-corrosion wood) on the market and is widely applied to fields such as door and window furniture, tourism real estate, and building energy conservation;

[0010] Compared with natural wood which requires a certain growth period and anti-corrosion wood which also needs to go through anti-corrosion process treatment, this composite material can be quickly produced in the factory, with higher production efficiency and more cost-effective;

[0011] Moreover, in the production process of this composite material, each chemical raw material reacts fully, there is no toxic residue, and the environmental protection grade reaches E0 level, while the highest environmental protection grade of anti-corrosion wood on the market is only E1 level, and its environmental protection performance is more excellent.

[0012] (4) In terms of acid and alkali resistance and anti-corrosion and moisture-proof, natural wood contains cellulose, gum, etc. These plant polysaccharides are water-soluble and are easily decomposed and rotted by molds and bacteria in the environment, and their acid and alkali resistance and anti-corrosion and moisture-proof capabilities are poor. In this composite material, the chemical bonds formed by the chemical reaction of rigid polyurethane foam are very stable in the environment, not easy to hydrolyze and difficult to be decomposed by bacteria and molds in the environment. After being soaked in acid solution or alkali solution for 30 days, there is no change in appearance.

[0013] (5) In terms of dimensional stability, the dimensional stability ≤ 1.5%, and the linear thermal expansion coefficient (1 / ℃) ≤ 1×10 -5 , with a low deformation rate, can remain stable during extreme temperature changes, and has strong anti-cracking performance.

[0014] In summary, this composite material combines high strength and high density, excellent mechanical properties (such as shear resistance and compressive resistance), as well as good heat insulation, acid and alkali resistance, corrosion and moisture resistance, and dimensional stability. It can be used in non-structural materials such as the core materials of doors, windows, and walls.

[0015] Furthermore, the density of the rigid polyurethane foam is 100 - 300 Kg / m 3 , and the density range of the reinforcing fiber is 1 - 2.7 g / cm 3 ; the mass ratio of the rigid polyurethane foam to the reinforcing fiber is 1:1 - 4:1.

[0016] When the non-combustible fiber is selected as the reinforcing fiber, according to the test method for the numerical content of glass fiber reinforced plastics GB / T·2577 - 2005, the composite material specimen is burned and then calculated to obtain the proportion of the fiber.

[0017] The inventor found that due to the relatively large density of the reinforcing fiber, if the proportion in the total mass of the composite material is less than 20%, the fiber adsorbing the polyurethane mixture (such as the maximum resin adsorption amount of each fiber is 120% of its own mass) is not enough to fill the product cavity during the foaming process, resulting in voids and hole defects, which affect the product quality. However, if the proportion in the total mass of the composite material exceeds 50%, it will affect the lightweight effect of the composite material. Therefore, the proportion of the reinforcing fiber in the composite material being 20% - 50% is an ideal content, which can not only improve the product quality but also not affect the lightweight effect of the finished product.

[0018] Furthermore, the nail-holding force of the composite material ≥ 500 N, and the nail-holding force is close to that of natural wood (such as pine). After the nail enters the board, the nail is easy to fix in the nail hole and not easy to loosen and fall off, and the nail hole can be reused, and vice versa.

[0019] Furthermore, the reinforcing fiber is one or a mixture of continuous glass fiber, glass fiber mat, bamboo fiber, and polymer fiber. Different fibers are selected: continuous glass fiber (density 2.6 g / cm 3 ), continuous glass fiber mat (density 2.6 g / cm 3 ), bamboo fiber (1.49 g / cm 3 ), chemical fiber (commonly such as PP / PET spun fiber with a density of 1.0 - 1.2 g / cm 3 ). According to different fiber densities and designed dosages, the composite material is made to maintain the characteristics of light weight and high strength through formula design.

[0020] Furthermore, the raw materials of the rigid polyurethane foam include material A and material B, and the mass ratio of material A to material B is 1:0.9 - 1:1.2.

[0021] The polyurethane foam produced with this formulation exhibits excellent performance in aspects such as thermal insulation, acid and alkali resistance, anti-corrosion and moisture-proof, and dimensional stability.

[0022] Furthermore, the B component is isocyanate or modified isocyanate, and the A component comprises raw materials in the following parts by mass:

[0023] 100 parts of combined polyether;

[0024] 0.5 - 1.5 parts of catalyst;

[0025] 1.0 - 3 parts of surfactant;

[0026] 0.6 - 1 part of foaming agent.

[0027] The modified isocyanate used in the B component is a product obtained through the chemical reaction of isocyanate. With the above formulation of the A component, it can ensure that the rise time of the polyurethane foam is ≥ 2 min, and the density of the foamed polyurethane foam is 100 - 300 Kg / m 3 .

[0028] Furthermore, this combined polyether is polymerized with propylene oxide as the polymerization monomer, using polyol and / or polyamine as the initiator, and is capped with propylene oxide. Its hydroxyl value is 30 - 500 mg·KOH / g, the average functionality is 2 - 6 (preferably 3 - 4.5), and the number-average molecular weight is 200 - 4800 (preferably 400 - 3000).

[0029] The initiator can be selected from one or more of glycerol, triethanolamine, pentaerythritol, diethylene glycol, sorbitol, and sucrose, preferably one or more of pentaerythritol, diethylene glycol, sorbitol, and sucrose;

[0030] When the average functionality of the combined polyether is greater than 2, it can improve the crosslinking degree, hardness, strength, and chemical dissolution / corrosion resistance of this composite material. However, the greater the functionality of the polyether, the greater the viscosity and the poorer the fluidity. Therefore, it is controlled below 6.

[0031] Furthermore, the isocyanate or modified isocyanate is aliphatic, alicyclic, araliphatic, aromatic isocyanate or a combination thereof.

[0032] Among them, the aliphatic isocyanate can be selected from alkylene diisocyanate, especially alkylene diisocyanate with 4 to 12 carbon atoms in the alkylene group, such as 1,12-dodecane diisocyanate, 2-ethyltetramethylene-1,4-diisocyanate, 2-methyl-pentamethylene-1,5-diisocyanate, 2-ethyl-2-butylpentamethylene-1,5-diisocyanate, tetramethylene-1,4-diisocyanate, and hexamethylene-1,6-diisocyanate, etc.;

[0033] Alicyclic isocyanates may include cyclohexane-1,3-diisocyanate, cyclohexane-1,4-diisocyanate, 1-isocyanate-3,3,5-trimethyl-5-isocyanato-methylcyclohexane (isophorone diisocyanate), 2,4-hexahydrotoluene diisocyanate, 2,6-hexahydrotoluene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, 2,2'-dicyclohexylmethane diisocyanate, 2,4'-dicyclohexylmethane diisocyanate, etc.

[0034] Aromatic isocyanates may be selected from diphenylmethane diisocyanate (such as 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 2,2'-diphenylmethane diisocyanate), polymethylene polyphenyl isocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 2,4-toluene diisocyanate and 2,6-toluene diisocyanate.

[0035] The aromatic aliphatic isocyanate may be xylylene diisocyanate (such as m-xylylene diisocyanate, p-xylylene diisocyanate), etc. These isocyanates may be used alone or in combination.

[0036] Furthermore, the catalyst is mainly a heat-sensitive delayed catalyst. Before the environment reaches the catalyst deblocking temperature (50°C to 60°C), its catalytic effect is weak and the polyurethane chemical reaction is relatively slow, which can ensure that the polyurethane and the reinforcing fibers are fully infiltrated before the curing reaction.

[0037] Select a thermosensitive delayed catalyst, specifically one or more of an amine catalyst, an organic bismuth / organic tin catalyst, and a trimerization catalyst with a thermosensitive group. The thermosensitive catalyst includes a class of nitrogen element compounds, organic metal compounds, etc. with thermosensitive groups such as nitrogen heterocyclic carbenes, quaternary ammonium salts, aldimines, and phenol sulfonates as trimerization catalysts for aliphatic and aromatic isocyanates. The characteristic of this type of catalyst is that under the heating conditions of the system, the active center protected by the thermosensitive group separates to form an activation center, activates the -NCO and -OH groups, and catalyzes the polyurethane gel reaction. This thermosensitive catalyst can effectively delay the reaction time of the system, ensure the sufficient infiltration time of the polyurethane raw materials and continuous fibers in the early stage (generally requiring 4 to 10 minutes), and can quickly react and cure after entering the plate chain line in the later stage (ensuring that the curing completion time is 25 to 40 minutes). For example, the formate of 2-hydroxy-N,N,N-trimethyl-1-propylamine, N,N',N"-tris(dimethylaminopropyl)-hexahydrotriazine, and 2,4,6-tris(dimethylaminomethyl)phenol are commonly used tertiary amine trimerization catalysts.

[0038] Further, the blowing agent is water. Using small molecule hydrocarbons such as Freon and cyclopentane as blowing agents in the traditional way will produce substances that are more harmful to the environment, such as fluorine. Using water as the blowing agent is more environmentally friendly.

[0039] Further, a flame retardant with a flame retardancy rating of B1 or above (classified according to the standard of "GB 8624-2012 Classification of the Burning Behavior of Building Materials and Products") is added to the composite material. The mass ratio of the composite material to the flame retardant is 10:1 to 10:4. The flame retardant does not chemically react with the A material, B material, and reinforcing fibers. The produced material can be used in places with a relatively high flame retardancy rating, such as doors and windows, walls, interior decoration, and carriage fillers.

[0040] Further, since organic flame retardants will release toxic gases when burning (for example, halogen-containing flame retardants generally release toxic and harmful gases of the HX type such as HCl and HBr), the flame retardant of the present invention selects inorganic filler-based flame retardants, which is more environmentally friendly.

[0041] Further, the inorganic filler-based flame retardant is one or a mixture of several of phosphorus-based, nitrogen-based, expanded graphite-based, magnesium hydroxide, and montmorillonite.

[0042] For example, the halogen-free phosphorus-based filler includes but is not limited to one or more of tris(2-chloropropyl) phosphate (TCPP), tris(2-chloroethyl) phosphate (TCEP), tris(2,3-dichloropropyl) phosphate (TDCP), tetra(2-chloroethyl) diethylene ether diphosphate, tetra(2-chloroethyl) ethylene diphosphate, and tetra(2-chloroethyl)-2,2-dichloromethyl-1,3-propylene diphosphate. The preferred addition amount is 5 to 20 mass parts.

[0043] The flame retardant also includes expanded graphite, preferably natural crystalline graphite that can instantaneously expand into a worm-like shape when encountering high temperature after special treatment. The expanded graphite is prepared by procedures known in the art and usually first modifies graphite with oxidants such as nitrates, chromates, peroxides, or opens the crystal layer by electrolysis, and then inserts nitrates or sulfates into the graphite; the expanded graphite can be selected as expandable graphite with an expansion ratio of 100 to 400 ml / g, a mesh number between 32 and 325 meshes, a pH value of 4 to 7, and a moisture content of not more than 1 wt%. Preferably, the expandable graphite with a mesh number of 80 to 250 meshes is selected, and the preferred addition amount is 5 to 15 mass parts.

[0044] The present invention also discloses a method for preparing a fiber-reinforced polyurethane composite material, which includes steps of arranging yarns on a yarn rack, injecting glue, impregnating, curing and forming, and cutting. In the impregnating step, a semi-closed vibration impregnating method is adopted for the impregnating tooling. First, a polyurethane high-pressure glue injector evenly sprays polyurethane raw materials on the surface of fibers, and then, through the left-right continuous vibration and extrusion of the tooling, the reinforcing fibers and the polyurethane raw materials are evenly impregnated.

[0045] Glass fibers are mainly longitudinally distributed parallel to the continuous traction direction of the plate chain (similar to the longitudinal texture of tree growth); in addition, due to the left-right lateral movement of the self-made impregnating tooling, some of the glass fibers are angled or perpendicular to the continuous traction direction of the plate chain, and some are transversely distributed. There are also a large number of disordered long fibers in the glass fibers. Under the vibration and extrusion of the impregnating tooling, some fibers show an angular and disordered distribution along the traction direction (similar to the transverse texture in wood). It is this combination of mainly longitudinal texture and partially disordered angular transverse texture that forms a unique solid wood texture.

[0046] By controlling the yarn arrangement and impregnating steps, the present invention enables the uniform mixing of fibers and polyurethane raw materials, and the performance of the product is uniform. It realizes the standardization and large-scale production of composite materials. In particular, through the semi-closed vibration impregnating method, the fibers are regularly distributed in the polyurethane, forming a shape close to the natural wood texture.

[0047] The present invention also discloses an application of the fiber-reinforced polyurethane composite material, and this composite material can be used as a thermal insulation filling material for walls and door and window cores. Description of the Drawings

[0048] Figure 1 is the process flow chart of the present invention;

[0049] Figure 2 is Figure 1 the structure diagram of the impregnating tooling in

[0050] The reference numerals in the drawings are: material bucket A 1, material bucket B 2, polyurethane glue injector 3, yarn rack 4, impregnating tooling 5, impregnating tank 51, eccentric mechanism 52, vibrating frame 53, oscillator 54, laminator 6, cutting machine 7. Detailed Embodiments

[0051] The following is a further detailed description through specific embodiments:

[0052] The batching and preparation method of the fiber-reinforced polyurethane composite material are as follows:

[0053] I. Raw Material Preparation

[0054] (I) Material A

[0055] It is composed of 100 parts of combined polyether, 1.5 parts of catalyst, 3 parts of surfactant, and 1 part of foaming agent.

[0056] (1) Combined polyether

[0057] The combined polyether has an average hydroxyl value of 328 and an average functionality of 3.85. Among them, the mass parts of polyether polyol Ⅰa: polyether polyol Ⅰb: polyether polyol Ⅰc are 25 parts, 50 parts, and 25 parts respectively.

[0058] Among them: (1) Polyether polyol Ⅰa: Using glycerol as the initiator, propylene oxide is polymerized by ring-opening and terminated with propylene oxide, and the number-average molecular weight is 2000; (2) Polyether polyol Ⅰb: Using a mixture of sucrose and diethylene glycol with a molar ratio of 3.7:6.3 as the initiator, propylene oxide is polymerized by ring-opening and terminated with propylene oxide, and the number-average molecular weight is 550; (3) Polyether polyol Ⅰc: Using a mixture of sorbitol and toluene diamine as the initiator, propylene oxide is polymerized by ring-opening, the functionality is 4, and the number-average molecular weight is 600;

[0059] (2) Catalyst: 1 part of catalyst Ⅳa: RM-301 from Guangzhou Yourun Synthetic Materials Co., Ltd. and 0.5 part of catalyst Ⅳb: SA-1 from Beijing Yintai Technology Co., Ltd.;

[0060] (3) Surfactant: Select surfactant Ⅱa: B8870 from Evonik Industries AG of Germany;

[0061] (4) Foaming agent: Select water as the foaming agent.

[0062] (II) Component B

[0063] Select polymeric MDI (full name: polyphenylmethane diisocyanate and its polymers), with an NCO (isocyanate group) content of 32 - 32.5% and an average functionality of 2.5 - 2.8.

[0064] (III) Reinforcing fiber

[0065] Select Tex9600 continuous glass fiber.

[0066] (IV) Flame retardant

[0067] Select a mixture of two flame retardants: (1) Flame retardant Ⅲa: tetra(2-chloroethyl) diethylene ether diphosphate; (2) Flame retardant Ⅲb: expandable graphite of 80 mesh. The mass part ratio of flame retardant Ⅲa to flame retardant Ⅲb is 1:1.

[0068] II. Raw material preparation

[0069] For Examples 1 - 4, prepare Component A, Component B, flame retardant, and continuous glass fiber according to the formula in Table 1.

[0070] Raw material name (parts by mass) Example 1 Example 2 Example 3 Example 4 Material A 100 100 100 100 Material B 120 120 120 120 Continuous glass fiber 220 55 94.2 94.2 Flame retardant 30 30 30 0

[0071] 3. Material preparation

[0072] See also Figure 1 , Figure 2 As shown, in the infiltration tool 5, the upper end of the infiltration tank 51 is open, see Figure 1 The left end is wide and the right end is narrow. A vibration frame 53 is arranged across the infiltration tank 51 along the width direction of the infiltration tank 51. The vibration frame 53 is in the shape of a letter "∏". The vibration frame 53 is connected to the output end of the eccentric mechanism 52 and can perform horizontal and vertical reciprocating motions driven by the eccentric mechanism 52. An oscillator 54 is connected to the middle of the vibration frame 53 through a suspension rod, and the oscillator 54 can oscillate when started. The connection method of the overall production line is as follows: A material barrel 1 and B material barrel 2 are respectively connected to the feed port of the polyurethane glue injection machine 3, the discharge port of the polyurethane glue injection machine 3 is connected to the liquid inlet of the infiltration tooling 5, the yarn outlet end of the yarn frame 4 is opposite to the wide mouth of the infiltration tank 51 of the infiltration tooling 5, the narrow mouth of the infiltration tank 51 is connected to the feed port of the laminator 6, and the outlet of the laminator 6 is connected to the cutting machine 7

[0073] Prepare the test pieces of Example 1, Example 2, Example 3 and Example 4 according to the following steps:

[0074] 1. Yarn arrangement on creel

[0075] The required number of glass fibers is calculated according to the density of the glass fibers and the size of the composite material, and the continuous glass fibers are passed through the creel 4, evenly arranged according to the cross section of the product, and passed through the impregnation tooling 5 for continuous traction.

[0076] 2. Glue injection

[0077] Add material A and flame retardant into material barrel A 1 and mix evenly, add material B into material barrel B 2, and the raw materials in material barrel A 1 and material barrel B 2 enter into polyurethane injection machine 3 at injection pressures of 11.0-11.5MPa and 10.0-10.5MPa respectively for mixing.

[0078] The temperature of the polyurethane injection machine 3 is controlled at 20-30° C., which is not yet at the catalyst deblocking temperature of 50-60° C., so that the A material and the B material react slowly, and the flame retardant does not react chemically with the A material and the B material.

[0079] 3. Infiltration

[0080] The urethane glue injection machine 3 injects the mixed polyurethane raw material into the impregnation tank 51 of the impregnation tool 5, first sprays it evenly on the surface of the glass fiber in the impregnation tank 51, and then uses the left and right continuous vibration and extrusion of the vibration frame 53 (the vertical reciprocating motion of the vibration frame 53 will squeeze the glass fiber), and the oscillator 54 will also perform oscillation and knocking motion to evenly impregnate the glass fiber and the polyurethane raw material. From the injection to the impregnation link, the rise time of the polyurethane foam is ≥2min, which fully guarantees the impregnation effect.

[0081] The glass fibers are mainly distributed longitudinally parallel to the continuous traction direction (similar to the longitudinal grain of a tree); in addition, due to the left and right lateral movement of the self-made impregnation tooling 5, the continuous fibers are partially angled or perpendicular to the continuous traction direction, and partially distributed transversely. There are also a large number of disordered long fibers in the glass fibers. Under the vibration and extrusion of the impregnation tooling 5, some of the fibers are randomly distributed at angles along the traction direction (similar to the transverse grain in wood). It is this combination of mainly longitudinal grains and partially disordered angular distribution of transverse grains that creates a unique texture of solid wood.

[0082] 4. Curing and molding

[0083] The polyurethane fully impregnated with the glass fiber enters the laminator 6, and the temperature in the laminator 6 is controlled at 60°C, at which time the catalyst deblocking temperature is reached, and the A material and the B material are foamed and formed, and the curing time is ≤40min.

[0084] 5. Cutting

[0085] The cured polyurethane material is cut into polyurethane material specimens of equal size by a cutting machine 7. Finally, Example 1, Example 2, Example 3, and Example 4 are manufactured into Specimen 1, Specimen 2, Specimen 3, and Specimen 4, respectively.

[0086] 3. Experimental testing

[0087] Prepare pine wood blocks of the same size as the polyurethane material specimens, and conduct experimental tests on specimens 1, 2, 3, and pine wood. The results are as follows:

[0088]

[0089]

[0090] From the test results, we can see that:

[0091] (1) Material density: The density of specimens 1, 2, 3 and 4 is 498 kg / m 3 、395Kg / m 3 、403Kg / m 3, 407 Kg / m 3 , all within the range of 300 - 500 Kg / m 3 The density of pine is 410 Kg / m 3 , and the densities of Specimens 1 - 4 are very close to that of pine. The specimens can be processed in the same ways as pine, such as shaving, sawing, and planing.

[0092] (2) Bending strength, shear strength, Shore hardness: The bending strengths of Specimen 1, Specimen 2, Specimen 3, and Specimen 4 are 105 MPa, 65 MPa, 87 MPa, and 90 MPa respectively, and the bending strength of pine is 55 MPa; the shear strengths of Specimen 1, Specimen 2, Specimen 3, and Specimen 4 are 21.2 MPa, 12.5 MPa, 17.3 MPa, and 18.5 MPa respectively, and the shear strength of pine is 7.5 MPa. The Shore hardnesses of Specimen 1, Specimen 2, Specimen 3, and Specimen 4 are 80 HA, 65 HA, 75 HA, and 78 HA respectively, and the hardness of pine is 60 HA.

[0093] It can be seen from this that the shear resistance, bending resistance, etc. of Specimens 1 - 4 are all higher than those of natural wood, and the hardness is also higher than that of natural solid wood. It has the characteristics of light weight and high strength, and will not lose its mechanical properties even when exposed to air for a long time. Therefore, in terms of performance, it can completely replace natural wood (or preservative-treated wood) on the market and be widely applied to fields such as doors and windows furniture, tourism real estate, and building energy conservation.

[0094] (3) Water absorption rate: The water absorption rates of Specimen 1, Specimen 2, Specimen 3, and Specimen 4 are 1.2%, 2.2%, 1.7%

[0095] 1.5% respectively, while the water absorption rate of pine is 19.3%. The water absorption rates of Specimens 1 - 4 are very different from those of natural solid wood, and they are not easy to absorb water, with more excellent waterproof and moisture-proof performance.

[0096] (4) Thermal conductivity: The thermal conductivities of Specimen 1, Specimen 2, Specimen 3, and Specimen 4 are 0.02 W / (m·K), 0.04 W / (m·K), 0.03 W / (m·K), and 0.03 W / (m·K) respectively, and the thermal conductivity of pine is 0.08 W / (m·K). It can be seen from this that the heat conduction performances of Specimens 1 - 4 are comparable to that of pine (the general range of thermal conductivity of thermal insulation materials is 0.03 - 0.17 W / (m·K)), and their heat insulation performances are close to those of natural solid wood;

[0097] (5) Dimensional stability, linear thermal expansion coefficient: The dimensional stabilities of Specimen 1, Specimen 2, Specimen 3, and Specimen 4 are 0.3%, 0.8%, 0.5%, and 0.5% respectively, and that of pine is 5.6%; the linear expansion coefficients of Specimen 1, Specimen 2, Specimen 3, and Specimen 4 are 0.3×10 -5 (1 / ℃), 0.7×10 -5(1 / °C), 0.5×10 -5 (1 / °C), 0.5×10 -5 (1 / °C), that of pine wood is 7.9×10 -5 (1 / °C). It can be seen that Specimens 1 - 4 have lower linear expansion coefficients and higher dimensional stabilities compared to pine wood, with low deformation rates, can remain stable under extreme temperature changes, and have strong crack resistance.

[0098] (2) Acid and alkali resistance: Specimens 1, 2, 3, 4 and pine wood were tested according to the method in the above table. The pine wood showed slight swelling, local fluffiness, and color change, while the appearances of the 4 specimens remained unchanged. It can be seen that Specimens 1 - 4 are very stable in acidic and alkaline environments and have stronger acid and alkali resistance than natural solid wood.

[0099] (3) Nail holding power: The nail holding powers of Specimens 1, 2, 3, and 4 are 835 N, 580 N, 731 N, and 740 N respectively, and that of pine wood is 498 N. The nail holding power of the composite material is greater than or close to that of natural solid wood. After the nail enters the board, it is easy to fix the nail hole and not easy to loosen and fall off, and the nail hole can be reused, and vice versa.

[0100] In summary, this composite material combines light weight and high strength, strong mechanical properties (such as anti - shear, hardness, etc.), heat insulation, acid and alkali resistance, anti - corrosion and moisture - proof, and good dimensional stability. Its performance is more comprehensive than that of natural woods such as pine wood. Moreover, it does not use chemical agents to enhance anti - corrosion, is more environmentally friendly and non - toxic than anti - corrosion wood, and is more suitable for doors and windows, filling, exterior decoration, etc.

[0101] The above are only embodiments of the present invention. Specific technical solutions and / or common knowledge such as characteristics well - known in the art are not described in detail here. It should be noted that for those skilled in the art, without departing from the technical solution of the present invention, several deformations and improvements can be made, which should also be regarded as the protection scope of the present invention, and these will not affect the implementation effect of the present invention and the practicality of the patent. The protection scope required by this application should be subject to the content of its claims, and the specific implementation manners described in the specification can be used to interpret the content of the claims.

Claims

1. A fiber-reinforced polyurethane composite material, characterized in that: The composite material contains rigid polyurethane foam and reinforcing fibers, and the material density is 300 - 500 Kg / m 3 ; the water absorption rate of the composite material is ≤5%, the Shore hardness is ≥60 HA, the flexural strength is ≥50 Mpa, the shear strength is ≥10 Mpa, the dimensional stability is ≤1.5%, the appearance remains unchanged after being soaked in acid solution or alkali solution for 30 days, the thermal conductivity is ≤0.05 W / (m·K), and the linear thermal expansion coefficient (1 / ℃) is ≤1×10 -5 ; the mass ratio of the rigid polyurethane foam to the reinforcing fibers is 1:1 - 4:

1. The raw materials of the rigid polyurethane foam include material A and material B, and the mass ratio of material A to material B is 1:0.9 - 1:1.

2. Material B is isocyanate or modified isocyanate, and material A includes the following raw materials in parts by mass: 100 parts of polyether polyol blend, 0.5 - 1.5 parts of catalyst, 1.0 - 3 parts of surfactant, and 0.6 - 1 part of blowing agent; the preparation method of the fiber-reinforced polyurethane composite material includes steps of yarn rack yarn arrangement, glue injection, infiltration, curing and forming, and cutting. From the glue injection step to the infiltration step, in the infiltration step, a semi-closed vibration infiltration method is adopted for the infiltration tooling. First, a polyurethane high-pressure glue injection machine evenly sprays the polyurethane raw materials on the surface of the fibers, and then through the left-right continuous vibration and extrusion of the tooling, the reinforcing fibers and the polyurethane raw materials are evenly infiltrated.

2. The fiber-reinforced polyurethane composite material according to claim 1, wherein: The density of the rigid polyurethane foam is 100 to 300 Kg / m 3 , and the density range of the reinforcing fiber is 1 to 2.7 g / cm 3 .

3. The fiber-reinforced polyurethane composite material according to claim 1 or 2, characterized in that: The nail-holding force of the composite material ≥ 500N.

4. The fiber-reinforced polyurethane composite material according to claim 3, wherein: The reinforcing fiber is one or a mixture of continuous glass fiber, glass fiber mat, bamboo fiber, and polymer fiber.

5. The fiber-reinforced polyurethane composite material according to claim 4, characterized in that: The hydroxyl value of the combined polyether is 30 - 500 mg·KOH / g, and the average functionality is 2 - 6.

6. The fiber-reinforced polyurethane composite material according to claim 5, wherein: The average functionality of the combined polyether is 3 - 4.

5.

7. The fiber-reinforced polyurethane composite material according to claim 6, wherein: The isocyanate or modified isocyanate is an aliphatic, alicyclic, araliphatic, aromatic isocyanate or a combination thereof.

8. The fiber-reinforced polyurethane composite material according to claim 7, characterized in that: The catalyst is a thermosensitive delayed catalyst.

9. The fiber-reinforced polyurethane composite material according to claim 8, wherein: The blowing agent is water.

10. The fiber-reinforced polyurethane composite material according to claim 9, characterized in that: A flame retardant with a flame retardant rating above B1 is added to the composite material, and the mass ratio of the composite material to the flame retardant is 10:1 - 10:

4.

11. The fiber-reinforced polyurethane composite material according to claim 10, characterized in that: The flame retardant is an inorganic filler type flame retardant.

12. The fiber-reinforced polyurethane composite material according to claim 11, wherein: The inorganic filler type flame retardant is one or a mixture of phosphorus-based, nitrogen-based, expanded graphite type, magnesium hydroxide, montmorillonite, etc.

13. Use of the fiber-reinforced polyurethane composite material according to any one of claims 1 to 12, characterized in that: This composite material can be used as a thermal insulation filling material for walls, door and window cores.

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