Polyurethane self-skinning foam material as well as preparation method and application thereof

Abstract

The invention discloses a polyurethane self-skinning foam material as well as a preparation method and application thereof, and the polyurethane self-skinning foam material is prepared by foaming a component A and a component B in a weight part ratio of 100: (25-60), the component A comprises 60-90 parts of polyether polyol, 10-40 parts of polymer polyol, 2-6 parts of a cross-linking agent, 0.3-1.5 parts of a catalyst, 0.2-0.5 part of a foam stabilizer, 5-20 parts of a foaming agent, 2-5 parts of a pore opening agent and 0.2-0.5 part of water; and the component B is organic isocyanate. The polyether polyol CHE-220DE contains an ether bond and a regularly arranged methylene structure, carbamate is generated, the compatibility with a cross-linking agent is improved, the reaction activity with isocyanate is high, and the chemical resistance stability is further improved by regulating and controlling the density, hardness and crust thickness of a polyurethane material; the foam stabilizer is combined with the cross-linking agent in the system, so that the cross-linking reaction with CHE-220DE is improved, the integrity, uniformity and regularity of a three-dimensional network cross-linking structure are promoted, the density and strength of foam are improved, and the smoothness and chemical stability of skin are improved.

Description

Technical Field

[0001] The invention relates to a polyurethane foam material, in particular to a polyurethane integral skin foam material and a preparation method and application thereof. Background Art

[0002] The brake fluid of a motor vehicle is a liquid medium that transmits brake pressure in the brake system and is an indispensable part. There are three main types: castor oil-alcohol type, synthetic type and mineral oil type. All of them contain a large amount of organic alcohol and anti-corrosion, lubricating or anti-rust additives. After a period of use, some components may absorb water or oxidize and change in performance, affecting the pH value and corrosion performance of the brake fluid, and then corroding the motor vehicle engine cover. At present, there are many studies on the manufacture of motor vehicle engine covers with self-skinning polyurethane foam. Self-skinning polyurethane foam has extremely high impact resistance, light weight, high resilience, adjustable hardness, easy coloring and molding, tough outside and soft inside. It is both a functional part and an appearance part. The surface in contact with the engine needs to have good sound absorption to prevent the noise generated by the engine from spreading to the cockpit when it is running; the surface not in contact with the engine needs to have a good appearance. The dense skin can form different patterns according to different molds, which is both beautiful and protective. The foam in the core reduces the density of the product and makes the product have a certain elasticity and good sound insulation effect, meeting the appearance requirements of users; at the same time, it has the properties of weight reduction, environmental protection and flame retardancy. Chinese patent CN112851910A discloses an aging-resistant and highly flame-retardant polyurethane sponge, a preparation method and its use. The polyurethane foam plastic is modified by using a special reactive flame retardant, and the surface hardness (Shore A) of the polyurethane foam plastic is 31-40, the tensile strength is 515-562 kPa, the elongation at break is 109-130%, the compressive strength is 35-50 kPa, and the flame retardancy is A-0, but the chemical stability is not mentioned. The high temperature resistance of polyurethane foam plastic is poor. Long-term exposure to high temperature environment or sunlight may cause material aging, deformation or even cracking, discoloration and brittleness, affecting the aesthetics, service life and safety; secondly, the chemical stability is poor, and contact with certain chemical substances may cause corrosion or dissolution; thirdly, the mechanical properties are greatly affected by the high humidity environment, and the strength and toughness of the material will be greatly reduced in a high humidity environment for a long time. The engine compartment is a high temperature and high humidity environment, and it is easily contaminated by brake fluid with complex components. These will cause the engine cover to expand, deform, crack or delaminate, thereby affecting the protection effect and sound absorption effect of the engine. Summary of the invention

[0003] Purpose of the invention: The purpose of the present invention is to improve the chemical stability of the engine hood and to provide a high-strength, corrosion-resistant polyurethane self-skinning foam material; another purpose of the present invention is to provide a method for preparing the above material; another purpose of the present invention is to provide the application of the above material in the preparation of the engine hood.

[0004] Technical solution: The polyurethane self-skinning foam material of the present invention is made by foaming component A and component B in a weight ratio of 100:25-60, in parts by weight; component A includes 60-90 parts of polyether polyol, 10-40 parts of polymer polyol, 2-6 parts of cross-linking agent, 0.3-1.5 parts of catalyst, 0.2-0.5 parts of foam stabilizer, 5-20 parts of foaming agent, 2-5 parts of cell opener, and 0.2-0.5 parts of water; component B is organic isocyanate.

[0005] Furthermore, the polyether polyol in component A is selected from CHE-220DE, a combination of CHE-220DE and CHE-330N, and a combination of CHE-220DE and CHE-2801L, and has a functionality of 2 to 3, a hydroxyl value of 28 to 56 mgKOH / g, and a viscosity of 300 to 1200 mPa·s at 25°C; the polymer polyol in component A is CHP-H45, which has a functionality of 3, a hydroxyl value in the range of 20 mgKOH / g, and a solid content in the range of 42%.

[0006] The polyether polyol in component A is CHE-220DE produced by Changhua Chemical, which is made by ring-opening polymerization of 1,4-butanediol in the presence of a cationic catalyst. It contains ether bonds and has a considerable number of regularly arranged methylene structures, which can generate more carbamates, increase the number of functional groups of polyurethane materials, resist corrosion from organic solvents such as acids, alkalis, and oils, and improve its chemical stability; at the same time, its functionality is 2, the average molecular weight is small, the viscosity is low, the polarity is small, the flexibility is good, the stability is good, the compatibility with the crosslinking agent is improved, and the reactivity with isocyanate is high. By adjusting the density, hardness and thickness of the crust of the polyurethane material, the chemical resistance stability is improved. The polarity of CHE-330N or CHE-2801L is relatively high, and the molecular chain end groups or side groups are not as regular and symmetrical as CHE-220DE. Although the compatibility with the crosslinking agent is improved, the irregular symmetrical structure affects the reaction with isocyanate, and the functional groups of carbamate that can be generated are less.

[0007] Furthermore, the cross-linking agent is selected from at least one of ethylene glycol or butanediol, and as a chain extender, reacts with isocyanate to generate a three-dimensional network cross-linked structure when curing the prepolymer, adjusts the polymer hard segment structure, and improves the final density, hardness, mechanical properties and chemical resistance of the material. In particular, when combined with CHE-220DE, which has a relatively regular molecular structure, the integrity of the three-dimensional network cross-linked structure can be improved, and the density, strength and chemical resistance of the structure can be improved.

[0008] Furthermore, the catalyst is a reactive tertiary amine catalyst, selected from at least one of DPA, A-1, Z-130, Polycat15 or Dabco33LV. It promotes the reaction of isocyanate with polyol and water, regulates the foaming and gelling reaction, promotes foam stability, maintains the intact shape and foam maturation to form a reinforced fiber structure, and improves the strength and elasticity of the material; in the later gelling process, it accurately regulates the milky time, rising curve and gelling time, regulates the maturation speed of the skin, improves the structure of the skin, and increases the density of the skin, thereby improving the appearance and chemical resistance of the skin of the self-skinning foam, and preventing the skin from expanding and deforming due to heat, cracking or delamination.

[0009] Furthermore, the foam stabilizer is a polysiloxane-olefin oxide block copolymer, selected from at least one of B8745, B8738, L-3627 or L-3628. The polysiloxane-olefin oxide block copolymer combines the hydrophobicity of siloxane and the hydrophilicity of olefin oxide, so that it has excellent emulsification, dispersion and wetting properties, and combines with the cross-linking agent in the system to reduce the surface tension of the system, improve the dispersion performance of the cross-linking agent in the system, and then improve the cross-linking reaction, further improve the integrity, density and strength of the three-dimensional network cross-linking structure, and then improve the smoothness and chemical resistance stability of the self-skinning foam surface.

[0010] Furthermore, the foaming agent is selected from at least one of HCFC-141b, HFC-245fa or dichloromethane, which has certain solubility and permeability, promotes a more complete foaming reaction, improves the fluidity of the foam, maintains the stability of the size of the foam, and thus improves the hardness and elasticity of the foam.

[0011] Furthermore, the cell opening agent is at least one of CHK-350A or CHK-350D. It promotes the formation of more open-cell structures in polyurethane foam, prevents foam shrinkage, stiffness or loss of elasticity, improves the air permeability and elasticity of foam, and is used in conjunction with the foaming agent to adjust the size, structure and density of foam, thereby improving the mechanical properties and chemical stability of foam.

[0012] Furthermore, the organic isocyanate of component B is selected from at least one of Cosmonate LL and Suprasec 2082. Both have low viscosity and fluidity. Cosmonate LL causes a high monomer volume, which makes the foam have certain high temperature resistance, UV resistance, corrosion resistance and high mechanical properties; Suprasec 2082 has a high functionality, which makes its reaction activity higher, improves the crosslinking property with polyols, improves the structure and density of the foam, and improves the stability and mechanical properties of the foam. The combination of the two can improve the mechanical properties and chemical stability of the foam while meeting the requirements of lightweight production.

[0013] The present invention also provides a method for preparing the above-mentioned polyurethane integral skin foam material, comprising the following steps:

[0014] Component A and component B in a weight ratio of 100:25-60 are mixed and stirred at high speed, injected into a closed mold, and molded and matured at 50-60° C. for 2-3 minutes to obtain a polyurethane foam material product.

[0015] The present invention also provides application of the polyurethane integral skin foam material in preparing an automobile engine hood.

[0016] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: 1. The polyether polyol in component A is selected from CHE-220DE produced by Changhua Chemical, which contains ether bonds and a considerable number of regularly arranged methylene structures, generates more carbamates, increases the number of functional groups of polyurethane materials, resists corrosion by organic solvents such as acids, alkalis, and oils, improves its chemical stability, improves compatibility with cross-linking agents, and has high reactivity with isocyanates. By regulating the density, hardness and thickness of the crust of the polyurethane material, the chemical resistance stability is improved; 2. The foam stabilizer is combined with the cross-linking agent in the system to reduce The surface tension of the cross-linking agent is increased, and the dispersion and permeability of the cross-linking agent in the system are improved, thereby improving the cross-linking reaction of CHE-220DE with a relatively regular molecular structure, improving the integrity, uniformity and regularity of the three-dimensional network cross-linking structure, improving the density and strength of the foam, and improving the smoothness and chemical resistance of the surface; 3. The foaming agent and the pore opening agent are used in combination to regulate the size, structure and density of the foam, thereby improving the mechanical properties and chemical stability of the foam, improving the hardness, tensile strength, compressive strength and elongation at break of the foam, and reducing its permanent deformation; 4. The high monomer Cosmonate LL is used in combination with the high-functionality Suprasec2082 to improve the structure and density of the foam, improve the stability, mechanical properties and aging corrosion resistance of the foam, and improve the mechanical properties and chemical stability of the foam while meeting the requirements of lightweight production. DETAILED DESCRIPTION

[0017] The technical scheme of the present invention is further described below in conjunction with the examples. The raw materials used in the examples are all commercially available, as shown in Table 1. The chemical foaming agent deionized water is homemade and meets the quality specifications of GB / T 6682-2016 grade 3 water.

[0018] Table 1 List of raw materials

[0019]

[0020] Table 2 shows the components and proportions (by weight) of Examples 1-6 and Comparative Examples 1-2, and blanks indicate that the component is not added. The preparation method of the polyurethane self-skinning foam material of the above-mentioned Examples and Comparative Examples comprises the following steps:

[0021] (1) preparing 60-90 parts of polyether polyol, 10-40 parts of polymer polyol, 2-6 parts of crosslinking agent, 0.3-1.5 parts of catalyst, 0.2-0.5 parts of foam stabilizer, 5-20 parts of foaming agent, 2-5 parts of cell opener, and 0.2-0.5 parts of water by weight, and stirring at room temperature to obtain component A;

[0022] (2) preparing an organic isocyanate in parts by weight to obtain component B;

[0023] (3) Component A and component B in a weight ratio of 100:25-60 are mixed and stirred at high speed, injected into a closed mold, and molded and matured at 50-60° C. for 2-3 minutes to obtain a polyurethane foam product.

[0024] Comparative Example 1: Based on Example 1, CHE-330N was used as the polyether polyol to replace CHE-220DE, and the remaining steps were the same.

[0025] Comparative Example 2: Based on Example 1, CHE-2801L is used as the polyether polyol to replace CHE-220DE, and the remaining steps are the same.

[0026] Table 2 Weight parts of each component raw material in the embodiments and comparative examples

[0027]

[0028] The polyurethane foam materials prepared in the above examples and comparative examples were tested for apparent density, hardness and mechanical properties (tensile strength, elongation at break, compressive strength and permanent deformation), and were immersed in motor vehicle brake fluid at room temperature for 24 hours. The chemical stability of the foam was tested by observing whether the surface was deformed, cracked or delaminated, as shown in Table 3 for details.

[0029] Table 3 Performance data of polyurethane integral skin foam material

[0030]

[0031] Comparing Example 1 and Comparative Examples 1-2, the polyurethane integral skin foam material prepared by replacing CHE-220DE with CHE-330N and CHE-2801L in component A has poor mechanical properties and poor chemical resistance. After being immersed in motor vehicle brake fluid at room temperature for 24 hours, the surface of the foam material obviously expands, and cracks and delamination occur. The polyether polyol in component A is CHE-220DE produced by Changhua Chemical, which is prepared by ring-opening polymerization of 1,4-butanediol in the presence of a cationic catalyst. It contains ether bonds and has a considerable number of regularly arranged methylene structures, which can generate more carbamates, increase the number of functional groups of the polyurethane material, resist corrosion from organic solvents such as acids, alkalis, and oils, and improve its chemical stability; at the same time, its functionality is 2, the average molecular weight is small, and the viscosity is low, which improves its compatibility with the cross-linking agent, thereby improving the density, hardness and thickness of the self-skinning of the polyurethane material, and further improving the chemical resistance; however, the polyether polyols CHE-330N and CHE-2801L in component A have a large molecular weight and viscosity, and their compatibility with the cross-linking agent is reduced, which affects the cross-linking reaction with isocyanate, the density, hardness and thickness of the self-skinning of the polyurethane foam, and thus affects the chemical resistance of the polyurethane foam. In addition, the amount of foaming agent, water and catalyst is controlled to control the reaction rate, thereby ensuring the balance of foaming and gel reaction, and a small amount of polymer polyol is added in combination with foam stabilizer and cell opener to make the foaming reaction more complete. When the system is in a low viscosity stage, the pore wall is stabilized, the pores grow to a suitable cell thickness, and conditions are created for subsequent cell opening. During the period from foam rising to maturation, the foam is prevented from being in an unstable state, the foam is kept in an intact shape, and the foam is promoted to mature to form a reinforced fiber structure, thereby preventing the gel reaction from being too fast so that the gas generated by the foaming reaction is enclosed in the cell structure, resulting in insufficient open porosity, separation, collapse, shrinkage, or coarse, stiff, uneven surface or stripes, etc., which in turn affects the dimensional stability and flexibility of the polyurethane material, so that the polyurethane foam has a higher load-bearing capacity and good rebound performance, improves the cell structure, cortical structure and appearance of the foam, further improves the chemical resistance and stability, and at the same time improves the uniformity of the foam, thereby improving the sound absorption effect of the polyurethane material under the premise of light weight.

[0032] Compared with Comparative Examples 1 and 2, the use of CHE-330N or CHE-2801L alone as the polyether polyol in component A has a greater impact on the apparent density of the polyurethane foam. The polarity of CHE-330N or CHE-2801L is relatively high, and the molecular chain end groups or side groups are irregularly symmetrical, which affects the reaction with isocyanate and the functional groups of the carbamate that can be generated are relatively few. In addition, CHE-330N in Comparative Example 1 has a trifunctional structure, low saturation, and high reactivity, which can promote the stability of foaming and the sufficiency of the cross-linking reaction, forming a three-dimensional network structure, so the apparent density is large; however, due to the irregular characteristics of the CHE-330N molecular structure, the three-dimensional network structure is irregular and uneven, and the hard skin layer is prone to expansion, cracking or delamination during use. CHE-2801L in Comparative Example 2 has a difunctional structure and a low degree of polymerization, which makes the formed three-dimensional network structure incomplete and irregular, resulting in a significant reduction in its apparent density, and it is also prone to expansion, cracking or delamination during use.

[0033] Comparing Examples 1-6, the apparent density of Examples 1 and 2 is higher, and the tensile strength, elongation at break and compressive strength are larger, mainly because the usage of the polyether polyol CHE-220DE in component A is larger, a large number of ether bonds and quite a number of regularly arranged methylene structures generate more carbamates to increase the number of functional groups of the polyurethane material, making the structure of the system more stable and elastic, and improving the mechanical strength of the material. Compared with other examples, the apparent density, surface hardness, tensile strength, elongation at break and compressive strength of Examples 3 and 4 are slightly lower, indicating that the compatibility of butanediol as a crosslinking agent with the polyether polyol in component A is not as good as that of ethylene glycol. Polymer polyols are easily attached to the foam wall and weaken the foam, which can overcome the problem of closed-cell foam to obtain a foam material with a higher open porosity and good resilience. However, when the amount of polymer polyol in component A of Example 5 is larger, the foam material prepared by it has good resilience and low density, resulting in a larger compression deformation. The apparent density and tensile strength of Example 2 are the largest, and the compression deformation is the smallest, mainly because component B uses Suprasec 2082, which has higher functionality, higher reactivity, and improved cross-linking, which can improve the structure and density of the foam, thereby increasing the apparent density and tensile strength of the foam, while reducing the compression deformation.

Claims

1. A polyurethane integral skin foam material, measured by weight, characterized in that: The invention is prepared by foaming component A and component B in a weight ratio of 100:25-60; the component A comprises 60-90 parts of polyether polyol, 10-40 parts of polymer polyol, 2-6 parts of crosslinking agent, 0.3-1.5 parts of catalyst, 0.2-0.5 parts of foam stabilizer, 5-20 parts of foaming agent, 2-5 parts of cell opener and 0.2-0.5 parts of water; the component B is organic isocyanate.

2. The polyurethane integral skin foam material according to claim 1, characterized in that: The polyether polyol in component A is selected from CHE-220DE, a combination of CHE-220DE and CHE-330N, and a combination of CHE-220DE and CHE-2801L, and has a functionality of 2 to 3, a hydroxyl value of 28 to 56 mgKOH / g, and a viscosity of 300 to 1200 mPa·s at 25°C; the polymer polyol in component A is selected from CHP-H45, and has a functionality of 3, a hydroxyl value in the range of 20 mgKOH / g, and a solid content in the range of 42%.

3. The polyurethane integral skin foam material according to claim 1, characterized in that: The cross-linking agent is selected from at least one of ethylene glycol and butanediol.

4. The polyurethane integral skin foam material according to claim 1, characterized in that: The catalyst is a reactive tertiary amine catalyst, and the foam stabilizer is a polysiloxane-olefin oxide block copolymer.

5. The polyurethane integral skin foam material according to claim 4, characterized in that: The reactive tertiary amine catalyst is selected from at least one of DPA, A-1, Z-130, Polycat15 and Dabco33LV; the polysiloxane-olefin oxide block copolymer is selected from at least one of B8745, B8738, L-3627 and L-3628.

6. The polyurethane integral skin foam material according to claim 1, characterized in that: The foaming agent is selected from at least one of HCFC-141b, HFC-245fa or dichloromethane.

7. The polyurethane integral skin foam material according to claim 1, characterized in that: The pore opening agent is at least one of CHK-350A and CHK-350D.

8. The polyurethane integral skin foam material according to claim 1, characterized in that: The organic isocyanate of component B is selected from at least one of Cosmonate LL and Suprasec 2082.

9. A method for preparing the polyurethane integral skin foam material according to any one of claims 1 to 8, characterized in that: The following steps are involved: Component A and component B in a weight ratio of 100:25-60 are mixed and stirred at high speed, injected into a closed mold, and molded and matured at 50-60° C. for 2-3 minutes to obtain a polyurethane foam material product.

10. Use of the polyurethane integral skin foam material according to any one of claims 1 to 8 in preparing an automobile engine hood.

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