Chopped jute fiber composite acoustic board

Abstract

The utility model discloses a chopped fibrilia composite acoustic board, belongs to the technical field of composite boards, and particularly relates to an acoustic board. The utility model aims to solve the problems that the conventional wood acoustic board is not mildew-proof and is easy to deform, and a mineral wool acoustic board and a fabric acoustic board cannot be degraded and are scratchy when being in contact with a human body. The chopped fibrilia composite acoustic board comprises a first surface layer, a first core layer, a framework core layer, a second core layer and a second surface layer, the first core layer is connected with the first surface layer and the framework core layer, and the second core layer is connected with the first surface layer and the framework core layer. The device is mainly used for preparing the chopped fibrilia composite material acoustic board.

Description

Technical Field

[0001] The utility model belongs to the technical field of composite boards, and in particular relates to a sound-absorbing board. Background Art

[0002] Sound-absorbing panels are a kind of sound-absorbing decorative material. With the emphasis on noise treatment in people's lives, sound-absorbing panels have been widely used. Existing sound-absorbing panels are divided into wooden sound-absorbing panels, mineral wool sound-absorbing panels and fabric sound-absorbing panels according to the material; wooden sound-absorbing panels are finely processed according to the acoustic principle and are divided into two types: grooved wood sound-absorbing panels and perforated wood sound-absorbing panels. Although wooden sound-absorbing panels are cheap, they have poor moisture-proof, mildew-proof and anti-deformation properties. The surface of the mineral wool sound-absorbing panel is treated with knurled mineral wool panels, and the surface is covered with holes of different depths, shapes and apertures. The core material of the fabric sound-absorbing panel is centrifugal glass wool, which has excellent sound absorption performance. Mineral wool in mineral wool sound-absorbing panels and centrifugal glass wool in fabric sound-absorbing panels are mainly used for filling, and can be wrapped with cloth. When used alone, they generally only have the effect of filling the cavity for sound insulation, but if the body touches it, it will be itchy, and it cannot be eliminated if it is inhaled into the human body. Utility Model Content

[0003] The utility model aims to solve the problems that the existing wooden sound-absorbing panels are not mildew-proof and easily deformed, and the mineral wool sound-absorbing panels and fabric sound-absorbing panels cannot be degraded and will cause itching when touched by the body, and provides a short-cut hemp fiber composite sound-absorbing panel.

[0004] A short-cut flax fiber composite sound-absorbing board comprises a first surface layer, a first core layer, a skeleton core layer, a second core layer and a second surface layer, wherein one side surface of the first surface layer is surface-connected to one side surface of the first core layer, the other side surface of the first core layer facing away from the first surface layer is surface-connected to one side surface of the skeleton core layer, the other side surface of the skeleton core layer facing away from the first core layer is surface-connected to one side surface of the second core layer, and the other side surface of the second core layer facing away from the skeleton core layer is surface-connected to one side surface of the second surface layer.

[0005] Advantages of the utility model: 1. The utility model uses hemp fiber as the main raw material to prepare the sound-absorbing board, which is green, environmentally friendly and degradable; 2. The utility model is divided into a first surface layer, a first core layer, a skeleton core layer, a second core layer and a second surface layer according to different hemp fibers, and a needle punching method is used to connect several fiber layers. The sound absorption performance of hemp fiber is related to airflow resistance, which reflects the resistance of air passing through unit materials, and acupuncture can improve the sound absorption performance in the low-frequency area. The utility model adopts a needle punching method to make the sound-absorbing board have good sound absorption performance; 3. The first surface layer, the first core layer, the second core layer and the second surface layer of the short-cut hemp fiber composite sound-absorbing board of the utility model are made of hemp fiber and low-melting point fiber; the multi-scale and multi-cavity structural characteristics of hemp fiber give it excellent sound absorption performance. Moreover, hemp fiber is cheap and easy to obtain, so increasing the proportion of hemp can reduce costs; low-melting point fiber can melt and diffuse during hot pressing, and low-melting point fiber can act as a binder. Low-melting point fiber can be widely dispersed along the needle-punched holes during melting and diffusion, blurring the interlayer stratification, greatly improving the connection performance between layers, and low-melting point fiber heats and consolidates to enhance the mechanical properties of the material, and the single performance can be changed by changing the proportion. 4. The material of the first surface layer and the second surface layer of the short-cut hemp fiber composite sound-absorbing board of the utility model is high hemp double-melting point composite fiber, the material of the first core layer and the second core layer is low hemp double-melting point composite fiber, and the material of the skeleton core layer is hemp fiber; due to the difference in materials, combined with the processing method of the utility model, the density of each layer of the short-cut hemp fiber composite sound-absorbing board of the utility model can be controlled, and the molding effect of all hemp fiber is not good, and different proportions of double-melting point fiber need to be added, which can be consistent with the proportion of high hemp fiber in the surface layer, and different from the surface layer in terms of different quantity and density. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 This is a schematic diagram of the structure of a short-cut flax fiber composite sound-absorbing board of the utility model;

[0007] Figure 2 This is a cross-sectional photo of the chopped flax fiber composite sound-absorbing board obtained in Example 2;

[0008] Figure 3 This is a 50-fold magnified SEM image of the chopped flax fiber composite sound-absorbing board obtained in Example 2;

[0009] Figure 4 This is a SEM image of the chopped flax fiber composite sound-absorbing board obtained in Example 2, magnified 200 times.

[0010] In the drawings, 1-first surface layer, 2-first core layer, 3-skeleton core layer, 4-second core layer, 5-second surface layer. DETAILED DESCRIPTION

[0011] Specific embodiment 1: This embodiment is a short-cut flax fiber composite sound-absorbing board, which includes a first surface layer 1, a first core layer 2, a skeleton core layer 3, a second core layer 4 and a second surface layer 5, one side of the first surface layer 1 is surface-connected to one side of the first core layer 2, the other side of the first core layer 2 facing away from the first surface layer 1 is surface-connected to one side of the skeleton core layer 3, the other side of the skeleton core layer 3 facing away from the first core layer 2 is surface-connected to one side of the second core layer 4, and the other side of the second core layer 4 facing away from the skeleton core layer 3 is surface-connected to one side of the second surface layer 5.

[0012] Specific embodiment 2: This embodiment is different from specific embodiment 1 in that the first surface layer 1 and the second surface layer 5 have the same thickness. Other aspects are the same as those of specific embodiment 1.

[0013] Specific embodiment 3: This embodiment is different from specific embodiment 1 or 2 in that the thickness ratio of the first surface layer 1 to the first core layer 2 is (0.5-1.5):3. The rest is the same as specific embodiment 1 or 2.

[0014] Specific embodiment 4: This embodiment is different from specific embodiments 1 to 3 in that the first core layer 2 and the second core layer 4 have the same thickness. Other aspects are the same as specific embodiments 1 to 3.

[0015] Specific embodiment 5: This embodiment differs from specific embodiments 1 to 4 in that the thickness ratio of the skeleton core layer 3 to the first core layer 2 is (1-2):3. The rest is the same as specific embodiments 1 to 4.

[0016] Specific embodiment 6: The difference between this embodiment and specific embodiments 1 to 5 is that the first surface layer 1 and the second surface layer 5 both have a density of 0.25 g / cm 3 ~0.35g / cm 3 The other parts are the same as those in the first to fifth embodiments.

[0017] Specific embodiment 7: The difference between this embodiment and specific embodiments 1 to 6 is that the first core layer 2 and the second core layer 4 both have a density of 0.09 g / cm 3 ~0.13g / cm 3 The other parts are the same as those in the first to sixth embodiments.

[0018] Specific embodiment 8: This embodiment differs from specific embodiments 1 to 7 in that: the skeleton core layer 3 has a density of 0.12 g / cm 3 ~0.17g / cm 3The other parts are the same as those in the first to seventh embodiments.

[0019] Specific embodiment 9: This embodiment is a method for preparing a chopped flax fiber composite sound-absorbing board, which is specifically completed according to the following steps:

[0020] 1. Preparation of high-hemp dual-melting-point composite fiber layer: ①, immerse hemp fiber and low-melting-point fiber in water to swell, then add water to loosen the fibers so that the fibers are evenly distributed in the water to obtain mixed fiber slurry I; the length of the hemp fiber is 3mm-12mm, and the length of the low-melting-point fiber is 3mm-12mm; ②, use a former to paper the mixed fiber slurry I to obtain a wet mixed fiber layer I; ③, shade-dry the wet mixed fiber layer I to obtain a single-layer mixed fiber layer I; ④, alternately lay the single-layer mixed fiber layer I according to the required thickness to obtain a high-hemp dual-melting-point composite fiber layer; the mass fraction of hemp fiber in the high-hemp dual-melting-point composite fiber layer is 70%-80%, and the mass fraction of low-melting-point fiber is 20%-30%;

[0021] 2. Preparation of low-hemp dual-melting-point composite fiber layer: ①, immerse hemp fiber and low-melting-point fiber in water to swell, then add water to loosen the fibers so that the fibers are evenly distributed in the water to obtain mixed fiber slurry II; the length of the hemp fiber is 3mm to 12mm, and the length of the low-melting-point fiber is 3mm to 12mm; ②, use a former to paper the mixed fiber slurry II to obtain a wet mixed fiber layer II; ③, shade-dry the wet mixed fiber layer II to obtain a single-layer mixed fiber layer II; ④, alternately lay the single-layer mixed fiber layer II according to the required thickness to obtain a low-hemp dual-melting-point composite fiber layer; the mass fraction of hemp fiber in the low-hemp dual-melting-point composite fiber layer is 30% to 60%, and the mass fraction of low-melting-point fiber is 40% to 70%;

[0022] 3. Acupuncture: ①. Use high-hemp double-melting-point composite fiber layer as the material of skeleton core layer 3, first surface layer 1 and second surface layer 5, use low-hemp double-melting-point composite fiber layer as the material of first core layer 2 and second core layer 4, respectively, use a needle punching machine to pre-needle punch the high-hemp double-melting-point composite fiber layer and the low-hemp double-melting-point composite fiber layer to obtain skeleton fiber felt, surface fiber felt and core fiber felt; ②. Stack them in the form of surface fiber felt, core fiber felt, skeleton fiber felt, core fiber felt and surface fiber felt in sequence, and then use a needle punching machine to vertically needle punch to obtain composite fiber felt; the thickness ratio of the surface fiber felt to the core fiber felt is (0.5-1.5):3, and the thickness ratio of the skeleton fiber felt to the core fiber felt is (1-2):3.

[0023] IV. Molding: ①. Cut the composite fiber felt according to the requirements, then put it into the mold, and use a hot press to heat press to obtain a chopped flax fiber composite blank; ②. Place the chopped flax fiber composite blank in an oven for thermosetting molding to obtain a chopped flax fiber composite profile; ③. Adjust the distance between the two hot rollers according to the required thickness, and then use the hot roller to perform surface finishing on the chopped flax fiber composite profile to obtain a chopped flax fiber composite sound-absorbing board; the density of the first surface layer 1 and the second surface layer 5 of the chopped flax fiber composite sound-absorbing board is 0.25g / cm 3 ~0.35g / cm 3 The density of the first core layer 2 and the second core layer 4 is 0.09 g / cm 3 ~0.13g / cm 3 The density of the skeleton core layer 3 is 0.12g / cm 3 ~0.17g / cm 3 .

[0024] The high-linen double-melting-point composite fiber and the low-linen double-melting-point composite fiber contain at least two fibers with different melting points. The fibers with relatively low melting points will melt after hot pressing and act as a binder, while the fibers with relatively high melting points act as a skeleton and play a supporting role.

[0025] Specific embodiment 10: This embodiment differs from specific embodiment 9 in that the low melting point fiber in step 1 ① and step 2 ① is a fiber with a melting point lower than 285° C. The rest is the same as specific embodiment 9.

[0026] Specific embodiment 11: This embodiment differs from specific embodiment 9 or 10 in that the low melting point fiber in step 1 ① and step 2 ① is polypropylene fiber, polyethylene terephthalate fiber or polylactic acid fiber. The rest is the same as specific embodiment 9 or 10.

[0027] The curl of the polylactic acid fiber in this embodiment is greater than that of the straight hemp fiber. When the polylactic acid fiber is used as the low-melting-point fiber, increasing the proportion of the two-component polylactic acid fiber can increase the space between the fibers, forming an air layer to enhance the sound insulation performance.

[0028] Specific embodiment 12: This embodiment differs from specific embodiments 9 to 11 in that the specific operation of the pre-acupuncture in step 3① is as follows: acupuncture is performed vertically with a fine needle at a puncture force of 5N to 20N using a needle machine, and the needle is evenly and vertically punctured at a spacing of 5mm to 15mm. After evenly and vertically puncturing one side, turn the side over and continue vertically puncturing, and vertically puncture one to two times on one side in total. The rest is the same as specific embodiments 9 to 11.

[0029] Specific Embodiment Thirteen: The difference between this embodiment and any one of Specific Embodiments Nine to Twelve is as follows: In step three ②, a needling machine is used to vertically needle with fine needles under a needling force of 5N to 20N, vertically needle uniformly at intervals of 1mm to 10mm. After vertically needling uniformly on one side once, turn it over and continue to vertically needle. Vertically needle a total of 2 to 5 times on one side to obtain a fiber felt. Others are the same as those in Specific Embodiments Nine to Twelve.

[0030] Specific Embodiment Fourteen: The difference between this embodiment and any one of Specific Embodiments Nine to Thirteen is as follows: The operating parameters of the hot pressing in step four ① are as follows: the hot pressing temperature is 100 to 130 °C, the pressure is 0.2 MPa to 0.8 MPa, and the hot pressing time is 3 min to 5 min. Others are the same as those in Specific Embodiments Nine to Thirteen.

[0031] Specific Embodiment Fifteen: The difference between this embodiment and any one of Specific Embodiments Nine to Fourteen is as follows: The specific operation of the thermosetting forming in step four ② is as follows: thermoset at a temperature of T °C for 10 min to 30 min. Let the melting point of hemp fiber be T1 and the melting point of the low-melting fiber be T2. T = T2 + (1 to 10) °C, and T < T1, to obtain a short-cut hemp fiber composite profile. Others are the same as those in Specific Embodiments Nine to Fourteen.

[0032] Specific Embodiment Sixteen: The difference between this embodiment and any one of Specific Embodiments Nine to Fifteen is as follows: The temperature of the hot roller in step four ③ is T0 °C. Let the melting point of hemp fiber be T1 and the melting point of the low-melting fiber be T2. T0 = T2 + (1 to 10) °C, and T0 < T1. Others are the same as those in Specific Embodiments Nine to Fifteen.

[0033] The content of the present utility model is not limited to the content of the above embodiments. The combination of one or several specific embodiments can also achieve the purpose of the utility model.

[0034] The following experiments are used to verify the effect of the present utility model:

[0035] Example 1: As Figure 1As shown, a method for preparing a chopped flax fiber composite sound-absorbing board, the chopped flax fiber composite sound-absorbing board comprises a first surface layer 1, a first core layer 2, a skeleton core layer 3, a second core layer 4 and a second surface layer 5, one side of the first surface layer 1 is surface-connected to one side of the first core layer 2, the other side of the first core layer 2 facing away from the first surface layer 1 is surface-connected to one side of the skeleton core layer 3, the other side of the skeleton core layer 3 facing away from the first core layer 2 is surface-connected to one side of the second core layer 4, and the other side of the second core layer 4 facing away from the skeleton core layer 3 is surface-connected to one side of the second surface layer 5; the thickness of the first surface layer 1 and the second surface layer 5 is 1 mm, the thickness of the first core layer 2 and the second core layer 4 is 4 mm, and the thickness of the skeleton core layer 3 is 3 mm;

[0036] This is done in the following steps:

[0037] 1. Preparation of high-hemp dual-melting-point composite fiber layer: ①, immerse hemp fiber and low-melting-point fiber in water to swell, then add water to loosen the fibers so that the fibers are evenly distributed in the water to obtain mixed fiber slurry I; the length of the hemp fiber is 3mm-12mm, and the length of the low-melting-point fiber is 3mm-12mm; ②, use a former to paper the mixed fiber slurry I to obtain a wet mixed fiber layer I; ③, shade-dry the wet mixed fiber layer I to obtain a single-layer mixed fiber layer I; ④, alternately lay the single-layer mixed fiber layer I according to the required thickness to obtain a high-hemp dual-melting-point composite fiber layer; the mass fraction of hemp fiber in the high-hemp dual-melting-point composite fiber layer is 75%, and the mass fraction of low-melting-point fiber is 25%;

[0038] 2. Preparation of low-hemp dual-melting-point composite fiber layer: ①, immerse hemp fiber and low-melting-point fiber in water to swell, then add water to loosen the fibers so that the fibers are evenly distributed in the water to obtain mixed fiber slurry II; the length of the hemp fiber is 3mm to 12mm, and the length of the low-melting-point fiber is 3mm to 12mm; ②, use a former to paper the mixed fiber slurry II to obtain a wet mixed fiber layer II; ③, shade-dry the wet mixed fiber layer II to obtain a single-layer mixed fiber layer II; ④, alternately lay the single-layer mixed fiber layer II according to the required thickness to obtain a low-hemp dual-melting-point composite fiber layer; the mass fraction of hemp fiber in the low-hemp dual-melting-point composite fiber layer is 45%, and the mass fraction of low-melting-point fiber is 55%;

[0039] 3. Acupuncture: ①, using a high-hemp double-melting-point composite fiber layer as the material of the skeleton core layer 3, the first surface layer 1 and the second surface layer 5, and using a low-hemp double-melting-point composite fiber layer as the material of the first core layer 2 and the second core layer 4, the high-hemp double-melting-point composite fiber layer and the low-hemp double-melting-point composite fiber layer are pre-needled by a needle punching machine to obtain a skeleton fiber felt, a surface fiber felt and a core fiber felt; ②, stacking the surface fiber felt, the core fiber felt, the skeleton fiber felt, the core fiber felt and the surface fiber felt in the form of a stack, and then vertically needle punching with a needle punching machine to obtain a composite fiber felt;

[0040] 4. Molding: ①. Cut the composite fiber felt according to the requirements, then put it into the mold, and use a hot press to heat press it to obtain a short-cut hemp fiber composite blank; ②. Place the short-cut hemp fiber composite blank in an oven for thermosetting molding to obtain a short-cut hemp fiber composite profile; ③. Adjust the distance between the two hot rollers according to the required thickness, and then use the hot roller to perform surface finishing on the short-cut hemp fiber composite profile to obtain a short-cut hemp fiber composite sound-absorbing board; the gram weight of the short-cut hemp fiber composite sound-absorbing board is 1656g / m 2 The weight of the first surface layer 1 and the second surface layer 5 is 254.7 g / m 2 The weight of the first core layer 2 and the second core layer 4 is 382.2 g / m 2 The weight of the skeleton core layer 3 is 382.2g / m 2 ;

[0041] The specific operation of the pre-needling described in step 3① of Example 1 is as follows: a needle machine is used to use a fine needle to perform vertical needling at a needling force of 10N, and the vertical needling is uniformly performed at a spacing of 10mm. After uniform vertical needling on one side once, turn over and continue vertical needling, and vertical needling on one side once in total.

[0042] In step three ② of Example 1, a needle punching machine is used to perform vertical needling with fine needles at a needling force of 10 N, and the needling is performed evenly at a spacing of 5 mm. After one side is evenly needled vertically once, the side is turned over and vertical needling is continued. The single side is vertically needled three times in total to obtain a fiber felt.

[0043] The operating parameters of the hot pressing described in step 4① of Example 1 are as follows: the hot pressing temperature is 120°C, the pressure is 0.5MPa, and the hot pressing time is 3min.

[0044] The specific operation of the thermosetting molding described in step 4② of Example 1 is as follows: thermosetting at a temperature of 170° C. for 20 minutes to obtain a chopped flax fiber composite profile.

[0045] The temperature of the hot roller in step 4 (3) of Example 1 is 170°C.

[0046] Embodiment 2: The difference between this embodiment and embodiment 1 is that the thickness of the first surface layer 1 and the second surface layer 5 is 0.8 mm, the thickness of the first core layer 2 and the second core layer 4 is 4.5 mm, and the thickness of the skeleton core layer 3 is 4 mm; the gram weight of the chopped flax fiber composite sound-absorbing board is 2018 g / m 2 The weight of the first surface layer 1 and the second surface layer 5 is 254.7 g / m 2 The weight of the first core layer 2 and the second core layer 4 is 477.7 g / m 2 The weight of the skeleton core layer 3 is 509.5g / m 2 . The rest is the same as Example 1.

[0047] Figure 2 : is a photograph of the cross section of the chopped flax fiber composite sound-absorbing board obtained in Example 2. The cross section of the chopped flax fiber composite sound-absorbing board obtained in Example 2 was observed using an electron microscope. Figure 3 and Figure 4 As shown, Figure 3 This is a 50-fold magnified SEM image of the chopped flax fiber composite sound-absorbing board obtained in Example 2. Figure 4 This is a 200-fold magnified SEM image of the chopped flax fiber composite sound-absorbing board obtained in Example 2. Figure 3 and Figure 4 There are gaps between the surface fibers, and the surface remains porous, so it has excellent sound absorption properties.

[0048] Embodiment 3: The difference between this embodiment and embodiment 1 is that the thickness of the first surface layer 1 and the second surface layer 5 is 0.8 mm, the thickness of the first core layer 2 and the second core layer 4 is 4 mm, and the thickness of the skeleton core layer 3 is 3 mm; the gram weight of the chopped flax fiber composite sound-absorbing board is 1783 g / m 2 The weight of the first surface layer 1 and the second surface layer 5 is 254.7 g / m 2 The weight of the first core layer 2 and the second core layer 4 is 382.2 g / m 2 The weight of the skeleton core layer 3 is 509.5g / m 2 . The rest is the same as Example 1.

[0049] The chopped flax fiber composite sound-absorbing board and wood wool board (thickness 30 mm, bulk density 520 kg / m 3 ), hemp fiberboard (thickness 20mm, bulk density 260kg / m 3 ) and glass wool board (thickness 50mm, bulk density 640kg / m 3 ) to test the sound absorption performance, and use the standing wave tube method to test the wood wool board (thickness 30mm, bulk density 520kg / m3 ), hemp fiberboard (thickness 20mm, bulk density 260kg / m 3 ) and glass wool board (thickness 50mm, bulk density 640kg / m 3 ), and the test results are shown in Table 1. The standing wave tube method is used to test the sound absorption coefficient and sound pressure changes of the chopped flax fiber composite sound-absorbing panels obtained in Examples 1 to 3 at different frequencies, and the test results are shown in Table 2.

[0050] Table 1

[0051]

[0052] Table 2

[0053]

[0054]

[0055] By comparing Table 2 with Table 1, it can be seen that the sound absorption performance of the short-cut flax fiber composite sound-absorbing board prepared by the utility model has reached the use requirements of the sound-absorbing board when the thickness is 9 mm.

[0056] The mechanical properties of the low-hemp dual-melting-point composite fiber layer obtained in step 2 of Example 1 were tested, and the test results were as follows: elongation was 8.0%, breaking length was 1.15 km, tensile strength was 68.0 kN, tensile strength was 4.53 kN / m, and tensile index was 11.2 N*m / g.

Claims

1. A chopped flax fiber composite sound-absorbing board, characterized in that It comprises a first surface layer (1), a first core layer (2), a skeleton core layer (3), a second core layer (4) and a second surface layer (5), wherein one side surface of the first surface layer (1) is surface-connected to one side surface of the first core layer (2), the other side surface of the first core layer (2) facing away from the first surface layer (1) is surface-connected to one side surface of the skeleton core layer (3), the other side surface of the skeleton core layer (3) facing away from the first core layer (2) is surface-connected to one side surface of the second core layer (4), and the other side surface of the second core layer (4) facing away from the skeleton core layer (3) is surface-connected to one side surface of the second surface layer (5); The first surface layer (1) and the second surface layer (5) have the same thickness; The thickness ratio of the first surface layer (1) to the first core layer (2) is (0.5-1.5):3; The first core layer (2) and the second core layer (4) have the same thickness; The thickness ratio of the skeleton core layer (3) to the first core layer (2) is (1-2):3; The first surface layer (1) and the second surface layer (5) both have a density of 0.25 g / cm 3 ~0.35g / cm 3 High hemp double melting point composite fiber layer; The first core layer (2) and the second core layer (4) both have a density of 0.09 g / cm 3 ~0.13g / cm 3 Low-hemp double-melting-point composite fiber layer; The skeleton core layer (3) has a density of 0.12 g / cm 3 ~0.17g / cm 3 High hemp double melting point composite fiber layer.

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