A degradable polylactic acid-polyether type polyurethane foam and a method for preparing the same

Abstract

The application provides a degradable polylactic acid-polyether type polyurethane foam and a preparation method thereof, and belongs to the technical field of high polymer materials. The degradable polylactic acid-polyether type polyurethane foam comprises the following raw materials in parts by mass: PLA 500 -PEG 400 -PLA 500 Polyol 50 parts, polytetrahydrofuran ether diol 50 parts, 1,4-butanediol 3.0-4.0 parts, foam stabilizer 1.0-1.5 parts, amine catalyst 0.10-0.20 parts, organic tin catalyst 0.03-0.06 parts, ethyl acetate 4.0-6.0 parts, and polymethylene polyphenyl isocyanate 50 parts. The method of the application adopts melt foaming, solves the problem that the raw materials are difficult to mix at room temperature because they are wax-like solids, and has simple process and low equipment requirement. The prepared polyurethane foam has fine and uniform cells, high closed cell rate, excellent elasticity, adjustable density, and is particularly suitable for midsoles of sports shoes, cushioning packaging, and environment-friendly shock-absorbing materials.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, specifically relating to a biodegradable polylactic acid-polyether type polyurethane foam and its preparation method. Background Technology

[0002] Polyurethane foam materials are widely used in thermal insulation, cushioning, sound insulation, sealing, and structural support, and have become an indispensable functional material in modern industry, construction, home furnishing, and transportation. Traditional polyurethane foams mostly use petroleum-based polyethers / polyester polyols, which are difficult to biodegrade, causing an environmental burden; in addition, some traditional materials have problems such as poor flame retardancy and the release of harmful gases.

[0003] Polylactic acid (PLA) has good biodegradability, but pure PLA is brittle, difficult to foam, and has poor compatibility with polyether polyols, easily delaminating. Among existing physical foaming agents: cyclopentane is flammable and requires explosion-proof equipment; supercritical CO2 foaming equipment is expensive and the process is complex, making it difficult to popularize. PLA-PEG-PLA block polyols can improve compatibility, but at room temperature, both PLA and polytetrahydrofuran ether diol (PTMEG) are waxy solids, making direct room-temperature foaming impossible. Summary of the Invention

[0004] The purpose of this invention is to provide a biodegradable polylactic acid-polyether type polyurethane foam and its preparation method, and to provide a simple, safe and environmentally friendly polyurethane foam with uniform cell structure and biodegradable preparation method, using ethyl acetate as a physical foaming agent to achieve stable foaming at normal pressure; effectively overcoming the drawbacks of the prior art.

[0005] To achieve the above or other objectives, the present invention is implemented through the following technical solutions.

[0006] A biodegradable polylactic acid-polyether type polyurethane foam, comprising the following raw materials in parts by weight: PLA 500 -PEG 400 -PLA 500 50 parts of polyol, 50 parts of polytetrahydrofuran ether diol, 3.0-4.0 parts of 1,4-butanediol, 1.0-1.5 parts of foaming agent, 0.10-0.20 parts of amine catalyst, 0.03-0.06 parts of organotin catalyst, 4.0-6.0 parts of ethyl acetate, and 50 parts of polymethylene polyphenyl isocyanate.

[0007] Preferably, the foam leveler is selected from foam leveler B8525. Preferably, the amine catalyst is selected from A33. Preferably, the organotin catalyst is selected from T-12 (dibutyltin dilaurate).

[0008] Preferably, the NCO index of polymethylene polyphenyl isocyanate is 1.03 to 1.05.

[0009] A method for preparing biodegradable polylactic acid-polyether type polyurethane foam includes the following steps: (1) Place PLA 500 -PEG 400 -PLA 500 A mixture of polyol and polytetrahydrofuran ether diol is heated and melted into a transparent, homogeneous liquid. (2) Add 1,4-butanediol, foaming agent, amine catalyst and organotin catalyst to the liquid obtained in step (1) in sequence, and stir until uniform; (3) Continue adding ethyl acetate and mix quickly until homogeneous; (4) Add polymethylene polyphenyl isocyanate, stir at high speed for 6-8 seconds, and quickly pour into the mold; (5) Free foaming at normal pressure, room temperature setting, and then curing to obtain biodegradable polyurethane foam.

[0010] Furthermore, the heating temperature in step (1) is 60-70°C.

[0011] Furthermore, in step (3), the curing temperature is 60°C and the curing time is 2 hours.

[0012] The polyurethane foam preparation method provided by this invention uses PLA 500 -PEG 400 -PLA 500 It exhibits excellent compatibility with PTMEG-2000, with no stratification or precipitation in the system. Ethyl acetate, as a physical foaming agent, is safe, miscible, halogen-free, and low in VOCs. The melt foaming process solves the problem of difficult mixing of waxy solid raw materials at room temperature, resulting in a simple process with low equipment requirements. The prepared polyurethane foam has fine and uniform pores, high closed-cell rate, excellent elasticity, and adjustable density, making it particularly suitable for sports shoe midsoles, cushioning packaging, and environmentally friendly shock-absorbing materials. The system contains a large number of PLA ester bonds, making it biodegradable. Detailed Implementation

[0013] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, unless otherwise specified, the following embodiments and features described therein can be combined with each other.

[0015] It should be noted that the terms such as "upper", "lower", "left", "right", "middle" and "one" used in this specification are only for clarity of description and are not intended to limit the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered as part of the scope of the invention.

[0016] The technical solution of the present invention will be described in detail below through several specific embodiments. Unless otherwise stated, the raw materials and reagents used in the following embodiments are commercially available products, or can be prepared by conventional methods in the art. Unless otherwise specified, the detection methods used in the embodiments of the present invention are conventional detection methods in the industry.

[0017] Example 1 A biodegradable polylactic acid-polyether type polyurethane foam, comprising the following raw materials in parts by weight: PLA 500 -PEG 400 -PLA 500 50 g; PTMEG-2000: 50 g; 1,4-Butanediol (BDO): 3.5 g; Foaming agent B8525: 1.2 g; Amine catalyst A33: 0.15 g; Organotin catalyst T-12: 0.04 g; Ethyl acetate: 5.0 g; Crude MDI: 50 g (NCO index approximately 1.04).

[0018] Preparation steps: (1) Place PLA 500 -PEG 400 -PLA 500 Add PTMEG-2000 to the reaction vessel, heat to 65°C to melt, and stir until a clear, homogeneous liquid is formed; (2) Add BDO, B8525, A33 and T-12 to the liquid in sequence and stir until well mixed; (3) Add ethyl acetate and mix quickly until homogeneous; (4) Add polymethylene polyphenyl isocyanate, stir at high speed for 7 seconds, and quickly pour into the mold; (5) Free foaming under normal pressure, set at room temperature, and then placed in a 60℃ oven for 2 hours to obtain biodegradable polyurethane foam. The resulting foam has fine and uniform cells, no cracks or collapses, good elasticity, and does not turn white or delaminate.

[0019] The obtained biodegradable polyurethane foam was density tested according to GB / T 6343-2009, and the measured density was 0.25 g / cm³. 3 According to GB / T 6670-2008, the rebound rate was tested and found to be 52%.

[0020] To evaluate the ability of the obtained polyurethane foam to recover its original shape after long-term compression, a compression set test was conducted. The test conditions were: compression ratio of 50%, temperature of 23℃, and duration of 72 h, resulting in a compression set rate of 12%.

[0021] The obtained biodegradable polyurethane foam was subjected to degradation experiments under composting conditions (58±2℃, relative humidity 50%~60%). After 30 days, the surface of the polyurethane foam showed obvious disintegration with a mass loss rate of 18%. After 90 days, the polyurethane foam structure was completely destroyed, exhibiting biodegradable characteristics.

[0022] Example 2 A biodegradable polylactic acid-polyether type polyurethane foam, comprising the following raw materials in parts by weight: PLA 500 -PEG 400 -PLA 500 50 g; PTMEG-2000: 50 g; 1,4-Butanediol (BDO): 3 g; Foaming agent B8525: 1 g; Amine catalyst A33: 0.1 g; Organotin catalyst T-12: 0.03 g; Ethyl acetate: 4.0 g; Crude MDI: 50 g (NCO index approximately 1.04).

[0023] Preparation steps: (1) Place PLA 500 -PEG 400 -PLA 500 Add PTMEG-2000 to the reaction vessel, heat to 60°C to melt, and stir until a clear, homogeneous liquid is obtained; (2) Add BDO, B8525, A33 and T-12 to the liquid in sequence and stir until well mixed; (3) Add ethyl acetate and mix quickly until homogeneous; (4) Add polymethylene polyphenyl isocyanate, stir at high speed for 7 seconds, and quickly pour into the mold; (5) Free foaming at normal pressure, room temperature setting, and then curing in a 60℃ oven for 2 hours to obtain biodegradable polyurethane foam.

[0024] Example 3 A biodegradable polylactic acid-polyether type polyurethane foam, comprising the following raw materials in parts by weight: PLA 500 -PEG 400 -PLA 500 50 g; PTMEG-2000: 50 g; 1,4-Butanediol (BDO): 4 g; Foaming agent B8525: 1.5 g; Amine catalyst A33: 0.2 g; Organotin catalyst T-12: 0.06 g; Ethyl acetate: 6.0 g; Crude MDI: 50 g (NCO index approximately 1.04).

[0025] Preparation steps: (1) Place PLA 500 -PEG 400 -PLA 500 Add PTMEG-2000 to the reaction vessel, heat to 70°C to melt, and stir until a clear, homogeneous liquid is obtained; (2) Add BDO, B8525, A33 and T-12 to the liquid in sequence and stir until well mixed; (3) Add ethyl acetate and mix quickly until homogeneous; (4) Add polymethylene polyphenyl isocyanate, stir at high speed for 8 seconds, and quickly pour into the mold; (5) Free foaming at normal pressure, room temperature setting, and then curing in a 60℃ oven for 2 hours to obtain biodegradable polyurethane foam.

[0026] Comparative Example 1 The formulation and preparation method in Comparative Example 1 are the same as in Example 1, except that 5.0 g of cyclopentane is used instead of ethyl acetate in Comparative Example 1. The foaming process during preparation is flammable, has poor safety, high VOC content, and produces an unpleasant odor in the foam.

[0027] Comparative Example 2 The formulation and preparation method in Comparative Example 2 were the same as in Example 1, except that 5.0 g of dichloromethane was used instead of ethyl acetate in Comparative Example 2. During the preparation process, the system turned white, separated into layers, PLA precipitated, and the foam cells were large and uneven, resulting in poor foam mechanical properties.

[0028] Comparative Example 3 The formulation and preparation method in Comparative Example 3 are the same as in Example 1. The difference from Example 1 is that step (1) is changed to mixing at room temperature (25°C), while the rest of the formulation remains the same. During the preparation process, the raw materials were found to be waxy solids, which could not be stirred evenly, and the foaming collapsed, failing to form complete foam.

[0029] In summary, the preparation method of this invention solves the problem of difficulty in mixing waxy solid raw materials at room temperature. The process is simple and requires minimal equipment. Moreover, the use of ethyl acetate as a physical foaming agent ensures safety, good miscibility, halogen-free properties, and low VOCs. Furthermore, the raw materials exhibit good compatibility, preventing the system from easily separating or precipitating.

[0030] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A biodegradable polylactic acid-polyether type polyurethane foam, characterized in that, Raw materials comprising the following parts by weight: PLA 500 -PEG 400 -PLA 500 50 parts of polyol, 50 parts of polytetrahydrofuran ether diol, 3.0-4.0 parts of 1,4-butanediol, 1.0-1.5 parts of foaming agent, 0.10-0.20 parts of amine catalyst, 0.03-0.06 parts of organotin catalyst, 4.0-6.0 parts of ethyl acetate, and 50 parts of polymethylene polyphenyl isocyanate.

2. A method for preparing the biodegradable polylactic acid-polyether type polyurethane foam of claim 1, characterized in that, Includes the following steps: (1) Place PLA 500 -PEG 400 -PLA 500 A mixture of polyol and polytetrahydrofuran ether diol is heated and melted into a transparent, homogeneous liquid. (2) Add 1,4-butanediol, foaming agent, amine catalyst and organotin catalyst to the liquid obtained in step (1) in sequence, and stir until uniform; (3) Continue adding ethyl acetate and mix quickly until homogeneous; (4) Add polymethylene polyphenyl isocyanate, stir at high speed for 6-8 seconds, and quickly pour into the mold; (5) Free foaming at normal pressure, room temperature setting, and then curing to obtain biodegradable polyurethane foam.

3. The method as described in claim 2, characterized in that, The heating temperature in step (1) is 60-70℃.

4. The method as described in claim 2, characterized in that, Step (3) The curing temperature is 60℃ and the curing time is 2 hours.