Preparation method of straw reinforced polyurethane foam plastic

Abstract

The invention discloses a preparation method of straw reinforced polyurethane foam plastic, and relates to the field of preparation methods of straw reinforced polyurethane foam plastic. The invention aims to solve the technical problems of complex preparation process, difficulty in degradation, high synthesis cost and difficulty in practical application of the existing fiber reinforcement. The method comprises the following steps: 1, pretreating straws to obtain straw sections or straw mats; 2, mixing polyether polyol, stannous octoate, triethanolamine, simethicone, water and a foaming agent to obtain a white material; and 3, compounding the black material isocyanate, the white material and the straw, curing and demolding. The treatment mode is simple, and a large amount of labor cost is saved. Meanwhile, the added straw can replace part of polyurethane foam, so that the use amount of the polyurethane foam is effectively reduced, the consumption of petroleum resources is reduced, and the mechanical property of the polyurethane foam is improved. The method is used for preparing the straw reinforced polyurethane foam plastic.

Description

Technical Field

[0001] The invention relates to the field of preparation methods of straw-reinforced polyurethane foam plastics. Background Art

[0002] The main use of polyurethane foam (PUF) is as a lightweight insulation material for building exterior walls. It is also used for insulation of refrigerators, freezers and cold storage. In order to improve the performance of polyurethane foam and expand its scope of use, different materials and processes have been used in recent years to modify rigid polyurethane foam and make it into a reinforced composite material. In the actual use process, due to the low compressive strength of polyurethane foam, it is difficult to meet more complex and diverse working scenarios, so it is necessary to study the enhancement and modification of polyurethane foam. In order to improve the strength of polymer foam and reduce the complexity of the preparation process, it is an ideal choice to introduce fibers as reinforcements into polyurethane foam by blending to prepare composite polyurethane foam. At present, the fibers used for reinforcing polyurethane foam are mainly glass fibers, carbon fibers and aromatic fibers. These fibers have high specific strength and high elastic modulus, which strengthen the bearing capacity of the pillars, slow down the deformation and damage of the materials, and can effectively improve the performance of polyurethane foam. However, the preparation process of fiber reinforcement is complicated, not easy to degrade, and the synthesis cost is high, which makes it difficult to apply in practice. Summary of the invention

[0003] The invention provides a method for preparing straw-reinforced polyurethane foam plastics in order to solve the technical problems that the current fiber reinforcement has a complicated preparation process, is not easy to degrade, has a high synthesis cost and is difficult to apply in practice.

[0004] A method for preparing straw-reinforced polyurethane foam plastics is specifically carried out according to the following steps:

[0005] Step 1: pre-treating the straw to obtain straw segments or straw mats;

[0006] Step 2: Mix polyether polyol, stannous octoate, triethanolamine, dimethyl silicone oil, water and a foaming agent to obtain a white material;

[0007] Step three: at room temperature, compound the black isocyanate, the white material obtained in step two and the straw treated in step one, foam and solidify them in a mold, and then demould to obtain the straw-reinforced polyurethane foam plastic.

[0008] Furthermore, if the straw used in step three is rice straw segments, the added mass of the rice straw segments is 5-15% of the total mass of the white material and the black material isocyanate.

[0009] Furthermore, in step three, the straw segments and the white material are evenly mixed, and then the black material isocyanate is added and stirred, and the stirring speed is controlled to be 1600r / min, and the stirring is performed for 10 to 15s to perform compounding.

[0010] Furthermore, if the straw used in step three is straw mat, the white material and the black material isocyanate are respectively injected into the two material barrels of the polyurethane foaming machine, the glue output is controlled to be 2g / s, the polyurethane foam is evenly sprayed on the bottom of the mold, and then the straw mat is laid, and then the polyurethane foam is sprayed, and the straw mat is laid, and multiple layers of straw mats are repeatedly stacked, and then the polyurethane foam is sprayed on the upper layer, and the mold is closed and solidified.

[0011] Plant fibers are mainly composed of lignin, cellulose and hemicellulose. The cellulose molecular structure contains a large number of hydroxyl groups, which can react chemically with isocyanate groups to improve the adhesion between the fiber and the foam matrix, and can partially replace the hydroxyl groups in polyester and polyether polyols, reducing the amount of non-renewable raw materials. At the same time, natural fibers with a high aspect ratio have a high cellulose content, showing high mechanical strength and modulus, which can improve the mechanical properties of polymer composites. Therefore, adding plant fibers to polyurethane foam can significantly improve its raw material composition and mechanical properties.

[0012] The preparation method of the present invention selects crop straws with hollow structures such as rice straw, wheat straw, and reed, which are abundant in source and low in price. The specific method is to combine polyether polyol (white material), polyisocyanate (black material), straw and other additives, fill them into a mold for foaming under the condition of full mixing and orderly arrangement of straw, apply a certain pressure, and prepare straw-reinforced polyurethane foam. Since the rice straw used is a long straw and a straw segment, the processing method is simple, and a large amount of labor costs can be saved. At the same time, the addition of straw can replace part of the polyurethane foam, effectively reduce the amount of polyurethane foam, reduce the consumption of petroleum resources, and improve the mechanical properties of polyurethane foam. At the same time, polyurethane foaming is simple to operate, and only needs to be foamed at room temperature, which is more convenient and energy-saving than the production method of other insulation boards.

[0013] The method of the invention is used for preparing straw-reinforced polyurethane foam plastics. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a photo of a straw-reinforced polyurethane foam plastic in Example 1, in which the added mass of the rice straw segment is 10% of the total mass of the white material and the black material isocyanate, wherein a 1 This is a photo of the appearance of straw-reinforced polyurethane foam with a straw segment of 1 cm. 1 This is a photo of the appearance of straw-reinforced polyurethane foam with a straw segment of 1.5 cm. 1 This is a photo of the appearance of straw-reinforced polyurethane foam with a straw segment of 2 cm. 1 This is a photo of the appearance of straw-reinforced polyurethane foam with a straw segment of 3 cm. 2This is a cross-sectional photo of a straw-reinforced polyurethane foam with a straw segment of 1 cm. 2 This is a cross-sectional photo of a straw-reinforced polyurethane foam with a straw section of 1.5 cm. 2 This is a cross-sectional photo of a straw-reinforced polyurethane foam with a straw segment of 2 cm. 2 This is a cross-sectional photo of a straw-reinforced polyurethane foam with a straw segment of 3 cm;

[0015] Figure 2 The graph is a compressive stress test result of straw-reinforced polyurethane foam obtained with different amounts of rice straw segments added in Example 1 with a relative strain of 10%, wherein SPUF-1 represents a straw segment length of 1 cm, SPUF-1.5 represents a straw segment length of 1.5 cm, SPUF-2 represents a straw segment length of 2 cm, and SPUF-3 represents a straw segment length of 3 cm;

[0016] Figure 3 The bending strength test result of straw-reinforced polyurethane foam obtained by adding different amounts of rice straw segments in Example 1 with a relative strain of 10%, wherein SPUF-1 represents a straw segment length of 1 cm, SPUF-1.5 represents a straw segment length of 1.5 cm, SPUF-2 represents a straw segment length of 2 cm, and SPUF-3 represents a straw segment length of 3 cm;

[0017] Figure 4 This is a graph showing the compressive stress test results of the straw-reinforced polyurethane foam prepared in Example 2;

[0018] Figure 5 This is a compressive strength stress-strain curve of the straw-reinforced polyurethane foam prepared in Example 2. DETAILED DESCRIPTION

[0019] Specific implementation method 1: This implementation method is a method for preparing straw-reinforced polyurethane foam plastic, which is specifically carried out according to the following steps:

[0020] Step 1: pre-treating the straw to obtain straw segments or straw mats;

[0021] Step 2: Mix polyether polyol, stannous octoate, triethanolamine, dimethyl silicone oil, water and a foaming agent to obtain a white material;

[0022] Step three: at room temperature, compound the black isocyanate, the white material obtained in step two and the straw treated in step one, foam and solidify them in a mold, and then demould to obtain the straw-reinforced polyurethane foam plastic.

[0023] Specific implementation method 2: This implementation method is different from specific implementation method 1 in that: in the pretreatment described in step 1, the straw is removed of floating liquid and dust, and cut into straw segments, and the length of the straw segment is 1 to 3 cm. The rest is the same as specific implementation method 1.

[0024] Specific implementation method 3: This implementation method is different from specific implementation method 1 or 2 in that: in the pretreatment described in step 1, the straw is cleaned and kept at a certain length, and then sewn into a straw mat. The rest is the same as specific implementation method 1 or 2.

[0025] Specific embodiment 4: This embodiment is different from specific embodiments 1 to 3 in that, by weight, the polyether polyol is 100 parts, stannous octoate is 0.5-1 parts, triethanolamine is 0.1-0.3 parts, dimethyl silicone oil is 2-5 parts, water is 0.5-2 parts, foaming agent is 10-17 parts, and isocyanate is 150-180 parts. Others are the same as specific embodiments 1 to 3.

[0026] Specific implementation 5: This implementation differs from Specific implementations 1 to 4 in that: if the straw used in step 3 is straw segments, the added mass of the rice straw segments is 5-15% of the total mass of the white material and the black material isocyanate. The rest is the same as Specific implementations 1 to 4.

[0027] Specific implementation 6: This implementation is different from specific implementations 1 to 5 in that: Step 3, the straw segments and the white material are mixed evenly, and then the black material isocyanate is added and stirred, and the stirring speed is controlled to 1600r / min, and stirred for 10 to 15s to compound. The rest is the same as specific implementations 1 to 5.

[0028] Specific implementation seven: This implementation is different from specific implementations one to six in that: if the straw used in step three is straw straw mat, then the white material and black material isocyanate are respectively injected into the two barrels of the polyurethane foaming machine, the glue output is controlled to be 2g / s, the polyurethane foam glue is evenly sprayed on the bottom of the mold, and then the straw straw mat is laid, and then the polyurethane foam glue is sprayed, and then the straw straw mat is laid, and multiple layers of straw straw mats are repeatedly stacked, and then the polyurethane foam glue is sprayed on the upper layer, and the mold is closed and solidified. The rest is the same as specific implementations one to six.

[0029] Specific embodiment 8: This embodiment is different from specific embodiments 1 to 7 in that the foaming agent in step 2 is n-pentane. The rest is the same as specific embodiments 1 to 8.

[0030] Specific embodiment 9: This embodiment differs from specific embodiments 1 to 8 in that the curing time in step 3 is 24 hours. The rest is the same as specific embodiments 1 to 8.

[0031] The content of the present invention is not limited to the content of the above-mentioned embodiments. The combination of one or several specific embodiments can also achieve the purpose of the invention.

[0032] Embodiment 1:

[0033] The present embodiment provides a method for preparing a straw-reinforced polyurethane foam, which is specifically carried out according to the following steps:

[0034] Step 1: Remove the floating liquid and dust from the straw, cut it into straw segments, cut it crosswise perpendicular to the growth direction of the straw, and the length of the straw segment is 1 cm, 1.5 cm, 2 cm, and 3 cm;

[0035] Step 2: At room temperature, 40 g of polyether polyol, 0.28 g of stannous octoate, 0.08 g of triethanolamine, 2 g of dimethyl silicone oil, 0.8 g of water and 4 g of n-pentane were mixed, and the straw segment obtained in step 1 was added and stirred to mix evenly, and then 60 g of isocyanate was added, the stirring speed was controlled to 1600 r / min, and the stirring was performed for 10 seconds to obtain a polyurethane foam;

[0036] Step 3: quickly pour the polyurethane foam obtained in step 2 into a mold for foaming and curing, and then demould it after standing at room temperature for 24 hours to obtain the straw-reinforced polyurethane foam plastic.

[0037] The straw-reinforced polyurethane foam prepared in this embodiment is denoted by SPUF, and the straw segments of different lengths obtained in step one are used to prepare straw-reinforced polyurethane foams in which the added mass of the rice straw segments in step two is 5%, 10% and 15% of the total mass of white and black isocyanates.

[0038] Figure 1 This is a photo of a straw-reinforced polyurethane foam plastic in Example 1, in which the added mass of the rice straw segment is 10% of the total mass of the white material and the black material isocyanate, wherein a 1 This is a photo of the appearance of straw-reinforced polyurethane foam with a straw segment of 1 cm. 1 This is a photo of the appearance of straw-reinforced polyurethane foam with a straw segment of 1.5 cm. 1 This is a photo of the appearance of straw-reinforced polyurethane foam with a straw segment of 2 cm. 1 This is a photo of the appearance of straw-reinforced polyurethane foam with a straw segment of 3 cm. 2 This is a cross-sectional photo of a straw-reinforced polyurethane foam with a straw segment of 1 cm. 2 This is a cross-sectional photo of a straw-reinforced polyurethane foam with a straw section of 1.5 cm. 2 This is a cross-sectional photo of a straw-reinforced polyurethane foam with a straw segment of 2 cm. 2This is a cross-sectional photo of a straw-reinforced polyurethane foam with a straw segment of 3 cm.

[0039] Figure 2 The graph is a compressive stress test result of straw-reinforced polyurethane foam obtained with different amounts of rice straw segments added in Example 1 with a relative strain of 10%, wherein SPUF-1 represents a straw segment length of 1 cm, SPUF-1.5 represents a straw segment length of 1.5 cm, SPUF-2 represents a straw segment length of 2 cm, and SPUF-3 represents a straw segment length of 3 cm;

[0040] Figure 3 This is a graph showing the bending strength test results of straw-reinforced polyurethane foam plastics with a relative strain of 10% obtained with different amounts of rice straw segments added in Example 1, wherein SPUF-1 represents a straw segment length of 1 cm, SPUF-1.5 represents a straw segment length of 1.5 cm, SPUF-2 represents a straw segment length of 2 cm, and SPUF-3 represents a straw segment length of 3 cm.

[0041] Figure 2 and Figure 3 As shown, pure polyurethane foam was used as the blank control group, and the performance results were measured as shown by the dotted line. The compressive stress of straw-reinforced polyurethane foam with a relative strain of 10% was higher than that of the control group; the bending strength of straw-reinforced polyurethane foam with a length of 1cm and 1.5cm rice straw was slightly lower than that of the control group, and the bending strength of straw-reinforced polyurethane foam with a length of 2cm and a rice straw content of 5% and 10% was improved, but when the rice straw content was further increased, the mechanical properties decreased slightly. The standard requires a minimum compressive strength of 80KPa, and there is no requirement for bending, which is generally greater than 0.25MPa.

[0042] Embodiment 2:

[0043] The present embodiment provides a method for preparing a straw-reinforced polyurethane foam, which is specifically carried out according to the following steps:

[0044] Step 1: Clean the straws, keep the length of the straws, and sew them into straw mats; the thickness of the straw mats is 0.8 cm;

[0045] Step 2: 40 g of polyether polyol, 0.28 g of stannous octoate, 0.08 g of triethanolamine, 1 g of dimethyl silicone oil, 0.4 g of water, and 6.8 g of n-pentane are mixed to obtain a white material, and the black material isocyanate is 40 g;

[0046] Step three, at room temperature, inject the white material and black material isocyanate described in step two into two material barrels of a polyurethane foaming machine respectively, control the glue output to be 2g / s, spray polyurethane foam glue evenly on the bottom of the mold, spray for 5 to 10s, then lay straw mats, spray polyurethane foam glue again, lay straw mats, repeatedly stack a total of 5 layers of straw mats, then spray polyurethane foam glue on the upper layer, solidify after closing the mold, and let it stand for 24 hours after demolding to obtain the straw-reinforced polyurethane foam plastic.

[0047] Figure 4 This is a graph showing the compressive stress test results of the straw-reinforced polyurethane foam prepared in Example 2;

[0048] Figure 5 This is a compressive strength stress-strain curve of the straw-reinforced polyurethane foam prepared in Example 2.

[0049] from Figure 4 and Figure 5 It can be seen that the compressive strength of pure polyurethane at relative strains of 40% and 75% are 0.027MPa and 0.053MPa respectively, while the compressive strength of straw-reinforced polyurethane foam at relative strains of 40% and 75% are 0.083MPa and 0.777MPa respectively, which are increased by 200% and 1300%.

[0050] In summary, the compressive strength of the straw-reinforced polyurethane foam obtained by the present invention is improved, and the random arrangement and directional arrangement structures of rice straw have a certain improvement effect on the mechanical strength of polyurethane foam plastics, which can better meet the needs of use while improving the utilization of green renewable resources.

Claims

1. A method for preparing straw-reinforced polyurethane foam, characterized in that The method is specifically carried out in the following steps: Step 1: pre-treating the straw to obtain straw segments or straw mats; Step 2: Mix polyether polyol, stannous octoate, triethanolamine, dimethyl silicone oil, water and a foaming agent to obtain a white material; Step three: at room temperature, compound the black isocyanate, the white material obtained in step two and the straw treated in step one, foam and solidify them in a mold, and then demould to obtain the straw-reinforced polyurethane foam plastic.

2. The method for preparing a straw-reinforced polyurethane foam according to claim 1, characterized in that In the pretreatment described in step 1, the straw is removed of floating liquid and dust, and cut into straw segments, the length of the straw segment is 1 to 3 cm.

3. The method for preparing a straw-reinforced polyurethane foam according to claim 1, characterized in that After the pretreatment described in step 1, the straw is cleaned, the length of the straw is maintained, and the straw is sewed into a straw mat.

4. The method for preparing a straw-reinforced polyurethane foam according to claim 1, characterized in that In parts by mass, the polyether polyol is 100 parts, stannous octoate is 0.5-1 parts, triethanolamine is 0.1-0.3 parts, dimethyl silicone oil is 2-5 parts, water is 0.5-2 parts, foaming agent is 10-17 parts, and isocyanate is 150-180 parts.

5. The method for preparing a straw-reinforced polyurethane foam according to claim 1, characterized in that If the straw used in step three is rice straw segments, the added mass of the rice straw segments is 5-15% of the total mass of the white material and the black material isocyanate.

6. The method for preparing a straw-reinforced polyurethane foam according to claim 5, characterized in that Step 3: Evenly mix the straw segments and the white material, then add the black material isocyanate and stir, control the stirring speed to 1600r / min, stir for 10 to 15s, and compound.

7. The method for preparing a straw-reinforced polyurethane foam according to claim 1, characterized in that If the straw used in step three is straw mat, inject the white material and black material isocyanate into the two material barrels of the polyurethane foaming machine respectively, control the glue output to 2g / s, spray the polyurethane foam glue evenly on the bottom of the mold, then lay the straw mat, spray the polyurethane foam glue again, lay the straw mat, repeatedly stack multiple layers of straw mat, spray the polyurethane foam glue on the upper layer, and solidify after closing the mold.

8. The method for preparing a straw-reinforced polyurethane foam according to claim 1, characterized in that The foaming agent in step 2 is n-pentane.

9. The method for preparing a straw-reinforced polyurethane foam according to claim 1, characterized in that The curing time of step three is 24h.

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