Bio-based soft polyurethane foam and preparation method thereof

Abstract

Belonging to the technical field of polyurethane materials, the invention discloses a bio-based soft polyurethane foam, which is prepared from the following raw materials by weight: 100 parts of polyol, 10-30 parts of a foam stabilizer, 0.2-0.3 part of a foaming agent, 0.03-0.05 part of a catalyst, and 40-60 parts of modified isocyanate. The polyol is prepared from 10 to 40 parts of bio-based polyol and 60 to 90 parts of polyether polyol. The invention also discloses a preparation method of the bio-based soft polyurethane foam, which comprises the following steps: mixing the bio-based polyol, the polyether polyol, the foam stabilizer, the foaming agent and the catalyst at normal temperature to obtain a premix, mixing the modified isocyanate and the premix, and coating a base membrane with the mixture for foaming to obtain the soft polyurethane foam. The bio-based soft polyurethane foam disclosed by the invention is high in flexibility, not easy to tear and small in compression hardness, and has a very good pressure-relieving and springback effect.

Description

Technical Field

[0001] The invention belongs to the technical field of polyurethane materials, and specifically relates to a bio-based soft polyurethane foam and a preparation method thereof. Background Art

[0002] Soft polyurethane foam is an easily compressible foam material. It is very suitable for applications that place special emphasis on flexibility, and can maintain its integrity and effectiveness in gap filling, padding and vibration isolation applications. It can meet the requirements of fixing and sealing smooth parts of various components, and is suitable for non-structural fixing and sealing of light and small materials, with excellent waterproof performance. Especially in the mobile phone industry in the electronics field, the display screen of the mobile phone is a glass structure, which faces the severe challenge of falling and breaking the screen. A high rate of falling and breaking the screen will cause a large number of repairs. Polyurethane foam can effectively buffer the impact caused by the moment of falling, thereby reducing the occurrence of broken screens, significantly improving the consumer experience, and reducing the probability of mobile phone repairs.

[0003] In recent years, with the miniaturization of electronic devices, the polyurethane foam used in electronic devices has become thinner and narrower. Even thin and narrow polyurethane foam must have high flexibility and low compression hardness, be able to effectively disperse impact damage stress, play a good buffering and shock absorbing effect, and quickly restore its shape after the stress is released. However, thin layers of polyurethane foam have not yet achieved the ideal effect, and still have problems such as easy tearing, poor toughness, high compression hardness, and unsatisfactory pressure-relief and rebound effects. Summary of the invention

[0004] In response to one or more of the above defects or improvement needs of the prior art, the present invention provides a bio-based soft polyurethane foam and a preparation method thereof, which solves the problems of existing thin-layer soft polyurethane foam being easy to tear, having poor flexibility, having high compression hardness, and having unsatisfactory pressure-absorbing and rebound effects.

[0005] To achieve the above object, according to one aspect of the present invention, a bio-based soft polyurethane foam is provided, which comprises the following raw materials in parts by weight:

[0006] 100 parts of polyol, 10-30 parts of foam stabilizer, 0.2-0.3 parts of blowing agent, 0.03-0.05 parts of catalyst, 40-60 parts of modified isocyanate; the polyol comprises 10-40 parts of bio-based polyol and 60-90 parts of polyether polyol.

[0007] As a further improvement of the present invention, the bio-based polyol has a hydroxyl value of 80 to 240 mg KOH / g and a functionality of 2 to 5; and / or,

[0008] The bio-based polyol is one or more of soybean oil polyol, rapeseed oil polyol, palm oil polyol, and loofah seed oil polyol.

[0009] As a further improvement of the present invention, the polyether polyol has a hydroxyl value of 20 to 300 mg KOH / g and a molecular weight of 500 to 6000; and / or,

[0010] The polyether polyol is one or more of polyether polyol 307, polyether polyol 1621, polyether polyol 3630, polyether polyol 330N, polyether polyol 3050, and polyether polyol 5054.

[0011] As a further improvement of the present invention,

[0012] The modified isocyanate is pentamethylene pentamethylene diisocyanate modified by diethylene glycol; the preparation method of the modified isocyanate comprises the following steps:

[0013] 100 parts of pentamethylene pentamethylene diisocyanate, 0.1-0.3 parts of antioxidant and 0.05-0.2 parts of self-polymerization catalyst are mixed and then self-polymerized to generate trimer, and 0.1-0.5 parts of polymerization inhibitor are added to terminate the reaction; 30-60 parts of diethylene glycol are then added to the trimer for prepolymerization, and the modified isocyanate is obtained by cooling.

[0014] As a further improvement of the present invention,

[0015] The antioxidant is one or more of antioxidant 1010 and antioxidant 168; and / or,

[0016] The self-polymerization catalyst is one or more of tetramethylammonium hydroxide and 2,4,6-tris(dimethylaminomethyl)phenol; and / or,

[0017] The polymerization inhibitor is o-toluenesulfonamide.

[0018] As a further improvement of the present invention,

[0019] The catalyst is an amine catalyst; and / or,

[0020] The foam stabilizer is silicone oil; and / or,

[0021] The foaming agent is water.

[0022] As a further improvement of the present invention, the thickness of the bio-based soft polyurethane foam is 0.4-1.0 mm.

[0023] According to another aspect of the present invention, a method for preparing a bio-based soft polyurethane foam is provided, which is used to prepare the bio-based soft polyurethane foam, comprising the following steps:

[0024] S1 prepares modified isocyanate;

[0025] 100 parts of pentamethylene pentamethylene diisocyanate, 0.1-0.3 parts of antioxidant, and 0.05-0.2 parts of self-polymerization catalyst are mixed and subjected to self-polymerization reaction to generate trimer, and 0.1-0.5 parts of polymerization inhibitor are added to terminate the reaction; 30-60 parts of diethylene glycol are added to the trimer for prepolymerization reaction, and the mixture is cooled to obtain modified isocyanate;

[0026] S2: mixing 10 to 40 parts of bio-based polyol, 60 to 90 parts of polyether polyol, 10 to 30 parts of foam stabilizer, 0.2 to 0.3 parts of foaming agent and 0.03 to 0.05 parts of catalyst to obtain a premix;

[0027] S3: 40 to 60 parts of the modified isocyanate in S1 and the premix in S2 are mixed, and the mixture is coated on a base film for foaming to obtain the bio-based soft polyurethane foam.

[0028] As a further improvement of the present invention, the -NCO content of the trimer is 28% to 45%, and the -NCO content of the modified isocyanate is 15% to 30%.

[0029] As a further improvement of the present invention,

[0030] In S1, the temperature of the self-polymerization reaction is 70-90°C and the time is 1-3 hours; the temperature of the pre-polymerization reaction is 50-90°C and the time is 1-3 hours; and / or,

[0031] In S1, the self-polymerization reaction and the pre-polymerization reaction are both carried out under an inert atmosphere; and / or,

[0032] In S1, the self-polymerization reaction and the pre-polymerization reaction are both carried out under stirring conditions; and / or,

[0033] In S3, the foaming temperature is 80 to 100° C., and the foaming time is 10 to 15 minutes.

[0034] In general, the above technical solution conceived by the present invention has the following beneficial effects compared with the prior art:

[0035] (1) The bio-based soft polyurethane foam of the present invention uses isocyanate modified by diethylene glycol, which can improve the flexibility of the polyurethane material. At the same time, diethylene glycol can also act as a cross-linking agent, making the foam difficult to tear; and the introduction of bio-based polyols synthesized from vegetable oils produces physical cross-linking with isocyanate, enhances the strength of the pore wall, improves the toughness of the foam, and makes it difficult to tear; in addition, the bio-based polyols also make the foam softer and have a good pressure-relieving effect due to their long fat chains. The bio-based soft polyurethane foam of the present invention has strong flexibility, low compression hardness, is easy to deform, can restore its shape after stress is released, and has a good pressure-relieving effect, which solves the problems of the existing thin-layer soft polyurethane foam being easy to tear, poor flexibility, high compression hardness, and unsatisfactory pressure-relieving rebound effect.

[0036] (2) Compared with the existing polyether polyols, the bio-based soft polyurethane foam of the present invention has the advantages of easy purchase of raw materials, low cost, and renewable, which can reduce the dependence on petrochemical products, has little pollution to the environment, and is beneficial to environmental protection. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0038] The embodiment of the present invention mainly improves the toughness and compression hardness of thin-layer polyurethane foam, while improving the toughness of thin-layer polyurethane foam without increasing the compression hardness of the foam, and the foam is soft and can play a good buffering role. As a preferred embodiment of the present invention, the bio-based soft polyurethane foam of the embodiment of the present invention includes the following raw materials in parts by weight: 100 parts of polyol, 10-30 parts of foam stabilizer, 0.2-0.3 parts of foaming agent, 0.03-0.05 parts of catalyst, 40-60 parts of modified isocyanate; wherein the polyol includes 10-40 parts of bio-based polyol and 60-90 parts of polyether polyol.

[0039] In a preferred embodiment, the bio-based polyol is one or more of soybean oil polyol, rapeseed oil polyol, palm oil polyol, and loofah seed oil polyol. The hydroxyl value of the bio-based polyol is preferably 80-240 mg KOH / g, and the functionality is preferably 2-5.

[0040] In a preferred embodiment, the hydroxyl value of the polyether polyol is preferably 20 to 300 mg KOH / g, and the molecular weight is preferably 500 to 6000. The polyether polyol is further preferably one or more of polyether polyol 307, polyether polyol 1621, polyether polyol 3630, polyether polyol 330N, polyether polyol 3050, and polyether polyol 5054.

[0041] In a preferred embodiment, the modified isocyanate is pentamethylene pentamethylene diisocyanate modified with diethylene glycol, and the modification method comprises the following steps:

[0042] 100 parts of pentamethylene pentamethylene diisocyanate, 0.1-0.3 parts of antioxidant and 0.05-0.2 parts of self-polymerization catalyst are mixed and then self-polymerized to generate trimer, and 0.1-0.5 parts of polymerization inhibitor are added to terminate the reaction; 30-60 parts of diethylene glycol are then added to the trimer for prepolymerization, and the mixture is cooled to obtain modified isocyanate.

[0043] More preferably, the antioxidant is antioxidant 1010 and / or antioxidant 168; the self-polymerization catalyst is tetramethylammonium hydroxide and / or 2,4,6-tris(dimethylaminomethyl)phenol; and the polymerization inhibitor is o-toluenesulfonamide.

[0044] In the embodiment of the present invention, the catalyst is preferably an amine catalyst, and more preferably one or more of tetramethylammonium hydroxide, triethanolamine, triethylenediamine, and tetramethyldiethylenetriamine;

[0045] In the embodiment of the present invention, the foam stabilizer is preferably silicone oil;

[0046] In the embodiment of the present invention, the foaming agent is preferably water, and more preferably deionized water or distilled water.

[0047] Furthermore, the preparation method of the bio-based soft polyurethane foam of the embodiment of the present invention comprises the following steps:

[0048] (1) preparing modified isocyanate;

[0049] 100 parts of pentamethylene pentamethylene diisocyanate, 0.1-0.3 parts of antioxidant, and 0.05-0.2 parts of self-polymerization catalyst are mixed and subjected to self-polymerization reaction to generate trimer, and 0.1-0.5 parts of polymerization inhibitor are added to terminate the reaction; 30-60 parts of diethylene glycol are added to the trimer for prepolymerization reaction, and the mixture is cooled to obtain modified isocyanate;

[0050] (2) mixing 10 to 40 parts of a bio-based polyol, 60 to 90 parts of a polyether polyol, 10 to 30 parts of a foam stabilizer, 0.2 to 0.3 parts of a foaming agent, and 0.03 to 0.05 parts of a catalyst to obtain a premix;

[0051] (3) Mixing 40 to 60 parts of the modified isocyanate in step (1) and the premix in step (2), coating the mixture on a base film and foaming the mixture to obtain the bio-based soft polyurethane foam.

[0052] Preferably, in step (1), the -NCO content of the trimer is 28% to 45%, and the -NCO content of the modified isocyanate is 15% to 30%. Specifically, after a certain period of self-polymerization, the -NCO content is tested, and when the content is 28% to 45%, an inhibitor is added to terminate the reaction; after a certain period of prepolymerization, the -NCO content is tested, and when the content is 15% to 30%, the modified isocyanate is obtained by cooling.

[0053] Preferably, in step (1), the temperature of the self-polymerization reaction is 70-90° C., and the time is 1-3 h; the temperature of the pre-polymerization reaction is 50-90° C., and the time is 1-3 h.

[0054] Preferably, in step (1), both the self-polymerization reaction and the pre-polymerization reaction are carried out under stirring, and the stirring speed is more preferably 100 to 300 r / min. In step (1), both the self-polymerization reaction and the pre-polymerization reaction are carried out under an inert atmosphere, and the inert atmosphere is more preferably nitrogen.

[0055] Preferably, in step (1), the addition rate of diethylene glycol is 20 to 30 g / min.

[0056] The cooling process in step (1) is not particularly limited in the present embodiment, and techniques well known to those skilled in the art may be used.

[0057] In step (2) of the embodiment of the present invention, the premix can be mixed at room temperature, and the mixing process is not particularly limited and can be carried out using techniques well known to those skilled in the art.

[0058] Preferably, in step (3), the foaming temperature is 80-100°C, the foaming time is 10-15 minutes; the modified isocyanate and the premix are mixed for 10-20 seconds; the base film is a PET film, more preferably a double-layer PET film. It is understood that after the foaming is completed, the embodiment of the present invention also preferably includes demolding the polyurethane foam plastic obtained by foaming. The embodiment of the present invention has no special restrictions on the coating process, demolding process, etc., and the techniques well known to those skilled in the art can be used.

[0059] The isocyanate used in the present invention is preferably pentamethylene diisocyanate (PDI). The synthetic raw material PDA comes from biomass corn or straw, which is a renewable resource and is green and environmentally friendly. In addition, PDI has a fatty chain structure, a more saturated and symmetrical molecular structure, a high carbon content, and low steric hindrance, and can significantly improve the toughness of polyurethane foam.

[0060] The invention further modifies PDI to obtain modified PDI. First, PDI is self-polymerized to form a trimer with a ring structure, and the -NCO content is kept at 28% to 45%. When the -NCO content exceeds 45%, the tear strength and compression hardness of the foam are not significantly improved. Compared with the commonly used toluene diisocyanate (TDI) and liquefied diphenylmethane diisocyanate (MDI) with a benzene ring, the trimer has low rigidity and good toughness. The invention then mixes the polyurethane soft segment material diethylene glycol with the PDI trimer for prepolymerization to obtain the modified PDI, and the -NCO content is kept at 15% to 30%. The -NCO content affects the hardness and strength of the material. When the -NCO content is high, the hardness and strength of the polyurethane material will increase. When the prepolymer isocyanate content is kept at 15% to 30%, the toughness of the material can be well improved. The diethylene glycol and the PDI trimer form a structure with a certain soft and hard segment ratio, which can improve the flexibility of the polyurethane material. At the same time, the diethylene glycol can also play the role of a cross-linking agent, so that the foam is not easy to tear.

[0061] Furthermore, the bio-based polyol used in the present invention is derived from vegetable oil, the main component of which is triglyceride, which is composed of three long-chain fatty acids. When the bio-based polyol is cross-linked with the modified isocyanate, the fatty carbon chain in the bio-based polyol can act as a hanging bond, and produce physical cross-linking with the modified isocyanate, thereby enhancing the strength of the pore wall, improving the toughness of the foam, and not easy to tear; at the same time, the bio-based polyol also makes the foam softer and has a good pressure-relieving effect because of its long fatty chain replacement of part of the polyether polyol. And compared with the existing polyether polyol, the bio-based polyol introduced in the present invention is easy to purchase raw materials, low in cost, renewable, can reduce dependence on petrochemical products, has little environmental pollution, and is beneficial to environmental protection.

[0062] The following are specific embodiments:

[0063] Example 1

[0064] 100g of pentamethylene pentamethylene diisocyanate was added to a reactor filled with nitrogen, heated to 70°C at a speed of 100r / min, then 0.1g of antioxidant 1010 and 0.1g of catalyst tetramethylammonium hydroxide were added to the reactor, kept warm for 1h, tested the -NCO content, when the content was 45%, 0.1g of inhibitor o-toluenesulfonamide was added to terminate the reaction. Then 30g of diethylene glycol was added, the temperature was raised to 85°C and kept warm for 1.5h, tested the -NCO content, when the content was 23.5%, cooled to obtain modified isocyanate;

[0065] 10 g of rapeseed oil polyol, 40 g of polyether polyol 330N, 50 g of polyether polyol 3630, 10 g of silicone oil, 0.2 g of deionized water and 0.03 g of triethanolamine were mixed to obtain a premix; the hydroxyl value of the rapeseed oil polyol was 100 mgKOH / g and the functionality was about 2.

[0066] 42 g of modified isocyanate and the above premix were mixed for 10 seconds, coated on a PET film, placed in an oven at 80° C. for foaming, the foaming aging time was 12 minutes, and then demolded to obtain a bio-based soft polyurethane foam.

[0067] Example 2

[0068] 100g of pentamethylene pentamethylene diisocyanate was added to a reactor filled with nitrogen, heated to 75°C at a speed of 150r / min, then 0.2g of antioxidant 1010 and 0.05g of catalyst tetramethylammonium hydroxide were added to the reactor, kept warm for 2h, and the -NCO content was tested. When the content was 35%, 0.2g of inhibitor o-toluenesulfonamide was added to terminate the reaction. Then 30g of diethylene glycol was added, the temperature was raised to 80°C and kept warm for 1h, the -NCO content was tested, and when the content was 21%, the modified isocyanate was obtained by cooling;

[0069] 20 g soybean oil polyol, 40 g polyether polyol 3050, 40 g polyether polyol 307, 15 g silicone oil, 0.3 g deionized water and 0.04 g triethanolamine were mixed to obtain a premix; the soybean oil polyol had a hydroxyl value of 210 mgKOH / g and a functionality of about 4.

[0070] 45 g of modified isocyanate and the above premix were mixed for 15 seconds, coated on a PET film, placed in an oven at 90° C. for foaming, the foaming aging time was 12 minutes, and then demolded to obtain a bio-based soft polyurethane foam.

[0071] Example 3

[0072] 100g of pentamethylene pentamethylene diisocyanate was added to a reactor filled with nitrogen, heated to 80°C at a speed of 200r / min, then 0.2g of antioxidant 1010 and 0.1g of catalyst tetramethylammonium hydroxide were added to the reactor, kept warm for 2h, tested the -NCO content, when the content was 28%, 0.3g of inhibitor o-toluenesulfonamide was added to terminate the reaction. Then 40g of diethylene glycol was added, the temperature was raised to 75°C and kept warm for 1.6h, tested the -NCO content, when the content was 19%, cooled to obtain modified isocyanate;

[0073] 30 g of palm oil polyol, 30 g of polyether polyol 5054, 40 g of polyether polyol 1621, 20 g of silicone oil, 0.3 g of deionized water and 0.05 g of triethylene diamine were mixed to obtain a premix; the palm oil polyol had a hydroxyl value of 80 mgKOH / g and a functionality of about 3.

[0074] 50 g of modified isocyanate and the above premix were mixed for 10 seconds, coated on a PET film, placed in an oven at 90° C. for foaming, the foaming aging time was 13 minutes, and then demolded to obtain a bio-based soft polyurethane foam.

[0075] Example 4

[0076] 100g of pentamethylene pentamethylene diisocyanate was added to a reactor filled with nitrogen, heated to 85°C at a speed of 250r / min, then 0.2g of antioxidant 1010 and 0.1g of catalyst tetramethylammonium hydroxide were added to the reactor, kept warm for 2h, the -NCO content was tested, when the content was 36%, 0.4g of inhibitor o-toluenesulfonamide was added to terminate the reaction. Then 45g of diethylene glycol was added, the temperature was raised to 70°C and kept warm for 1h, the -NCO content was tested, when the content was 18%, the modified isocyanate was obtained by cooling;

[0077] 40 g soybean oil polyol, 30 g polyether polyol 330N, 30 g polyether polyol 5054, 30 g silicone oil, 0.25 g deionized water and 0.04 g tetramethyldiethylenetriamine were mixed to obtain a premix; the soybean oil polyol had a hydroxyl value of 170 mgKOH / g and a functionality of about 3.

[0078] 55 g of modified isocyanate and the above premix were mixed for 12 seconds, coated on a PET film, placed in an oven at 100° C. for foaming, the foaming aging time was 14 minutes, and then demolded to obtain a bio-based soft polyurethane foam.

[0079] Example 5

[0080] 100g of pentamethylene pentamethylene diisocyanate was added to a reactor filled with nitrogen, heated to 90°C at a speed of 300r / min, then 0.2g of antioxidant 1010 and 0.1g of catalyst tetramethylammonium hydroxide were added to the reactor, kept warm for 1h, tested the -NCO content, when the content was 33%, 0.5g of inhibitor o-toluenesulfonamide was added to terminate the reaction. Then 40g of diethylene glycol was added, the temperature was raised to 65°C and kept warm for 2h, tested the -NCO content, when the content was 15%, cooled to obtain modified isocyanate;

[0081] 30g of luffa seed oil polyol, 60g of polyether polyol 3050, 10g of polyether polyol 5054, 25g of silicone oil, 0.3g of deionized water and 0.04g of triethylene diamine were mixed to obtain a premix; the luffa seed oil polyol had a hydroxyl value of 136mgKOH / g and a functionality of about 2.5.

[0082] 60 g of modified isocyanate and the above premix were mixed for 10 seconds, coated on a PET film, placed in an oven at 100° C. for foaming, the foaming aging time was 14 minutes, and then demolded to obtain a bio-based soft polyurethane foam.

[0083] Comparative Example 1

[0084] 60g of polyether polyol 5054, 40g of polyether polyol 307, 10g of silicone oil, 0.3g of deionized water and 0.04g of amine catalyst were mixed to obtain a mixture; 43g of toluene diisocyanate (TDI) and the mixture were mixed for 12s, coated on a PET film, placed in an oven at 100°C for foaming, the foaming aging time was 15min, and then demolded to obtain a soft polyurethane foam.

[0085] Comparative Example 2

[0086] 40g soybean oil polyol, 30g polyether polyol 330N, 30g polyether polyol 5054, 30g silicone oil, 0.25g deionized water and 0.04g tetramethyl diethylene triamine were mixed to obtain a premix; 43g liquefied diphenylmethane diisocyanate (MDI) and the premix were mixed for 15s, coated on a PET film, placed in an oven at 100°C for foaming, the foaming aging time was 13min, and then demolded to obtain a soft polyurethane foam. The soybean oil polyol has a hydroxyl value of 170mgKOH / g and a functionality of about 3.

[0087] Comparative Example 3

[0088] 40g soybean oil polyol, 30g polyether polyol 330N, 30g polyether polyol 5054, 30g silicone oil, 0.25g deionized water and 0.04g tetramethyl diethylene triamine are mixed to obtain a premix; 50g pentamethylene diisocyanate and the premix are mixed for 15s, coated on a PET film, placed in an oven at 100°C for foaming, the foaming aging time is 13min, and then demolded to obtain a soft polyurethane foam. The soybean oil polyol has a hydroxyl value of 170mgKOH / g and a functionality of about 3.

[0089] Comparative Example 4

[0090] 100 g of pentamethylene pentamethylene diisocyanate was added to a reactor filled with nitrogen, 0.2 g of antioxidant 1010 and 0.1 g of catalyst tetramethylammonium hydroxide were added to the reactor at a speed of 250 r / min, 45 g of diethylene glycol was added, the temperature was raised to 70° C. and kept for 1 h, the -NCO content was tested, and when the content was 18%, 0.4 g of inhibitor o-toluenesulfonamide was added to terminate the reaction, and the modified isocyanate was obtained by cooling;

[0091] 40 g soybean oil polyol, 30 g polyether polyol 330N, 30 g polyether polyol 5054, 30 g silicone oil, 0.25 g deionized water and 0.04 g tetramethyldiethylenetriamine were mixed to obtain a premix; the soybean oil polyol had a hydroxyl value of 170 mgKOH / g and a functionality of about 3.

[0092] 55 g of modified isocyanate and the above premix were mixed for 12 seconds, coated on a PET film, placed in an oven at 100° C. for foaming, the foaming aging time was 14 minutes, and then demolded to obtain a soft polyurethane foam.

[0093] Comparative Example 5

[0094] 100g of pentamethylene pentamethylene diisocyanate was added to a reactor filled with nitrogen, heated to 85°C at a speed of 250r / min, then 0.2g of antioxidant 1010 and 0.1g of catalyst tetramethylammonium hydroxide were added to the reactor, kept warm for 2h, the -NCO content was tested, when the content was 50%, 0.4g of inhibitor o-toluenesulfonamide was added to terminate the reaction. Then 45g of diethylene glycol was added to the reactor at a speed of 30g / min, the temperature was raised to 70°C and kept warm for 1h, the -NCO content was tested, when the content was 35%, the modified isocyanate was obtained by cooling;

[0095] 40 g soybean oil polyol, 30 g polyether polyol 330N, 30 g polyether polyol 5054, 30 g silicone oil, 0.25 g deionized water and 0.04 g tetramethyldiethylenetriamine were mixed to obtain a premix; the soybean oil polyol had a hydroxyl value of 170 mgKOH / g and a functionality of about 3.

[0096] 55 g of modified isocyanate and the above premix were mixed for 12 seconds, coated on a PET film, placed in an oven at 100° C. for foaming, the foaming aging time was 14 minutes, and then demolded to obtain a soft polyurethane foam.

[0097] The tear strength and compression hardness of Examples 1-5 and Comparative Examples 1-5 were tested according to Method A of GB / T16578.1-2008 and GB / T10807-2006. The test results are shown in Table 1.

[0098] Table 1 Test results of embodiments and comparative examples

[0099]

[0100]

[0101] It can be seen that the tear strength of the soft polyurethane foam in Examples 1-5 is ≥2.8N / cm, and the compression hardness is ≤22.8N, with high tear strength and low compression hardness. In Comparative Example 1, since no bio-based polyol is added, the degree of crosslinking of the polyurethane foam is smaller than that of the embodiment, and the tear strength of the foam is poor. In Comparative Example 2, an isocyanate with a benzene ring is used, and the rigidity of the benzene ring structure is large, resulting in a large compression hardness of the polyurethane foam. In Comparative Example 3, unmodified isocyanate is used, and the hard segment is an aliphatic carbon chain that directly reacts with the polyol. The degree of crosslinking is smaller than that of the modified isocyanate alicyclic carbon chain with the polyol, and the tear strength of the polyurethane foam is poor. In Comparative Example 4, diethylene glycol is directly prepolymerized with PDI to form an irregular structure of the prepolymer, resulting in poor tear strength of the polyurethane. In Comparative Example 5, the modified isocyanate is used as the hard segment in the polyurethane, and the -NCO content is too high, resulting in a large hardness of the polyurethane foam.

[0102] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A bio-based soft polyurethane foam, characterized in that: According to weight parts, it includes the following raw materials: 100 parts of polyol, 10-30 parts of foam stabilizer, 0.2-0.3 parts of blowing agent, 0.03-0.05 parts of catalyst, 40-60 parts of modified isocyanate; the polyol comprises 10-40 parts of bio-based polyol and 60-90 parts of polyether polyol.

2. The bio-based soft polyurethane foam according to claim 1, characterized in that: The bio-based polyol has a hydroxyl value of 80 to 240 mg KOH / g and a functionality of 2 to 5; and / or, The bio-based polyol is one or more of soybean oil polyol, rapeseed oil polyol, palm oil polyol, and loofah seed oil polyol.

3. The bio-based soft polyurethane foam according to claim 1, characterized in that: The polyether polyol has a hydroxyl value of 20 to 300 mg KOH / g and a molecular weight of 500 to 6000; and / or, The polyether polyol is one or more of polyether polyol 307, polyether polyol 1621, polyether polyol 3630, polyether polyol 330N, polyether polyol 3050, and polyether polyol 5054.

4. The bio-based soft polyurethane foam according to any one of claims 1 to 3, characterized in that: The modified isocyanate is pentamethylene pentamethylene diisocyanate modified by diethylene glycol; the preparation method of the modified isocyanate comprises the following steps: 100 parts of pentamethylene pentamethylene diisocyanate, 0.1-0.3 parts of antioxidant and 0.05-0.2 parts of self-polymerization catalyst are mixed and then self-polymerized to generate trimer, and 0.1-0.5 parts of polymerization inhibitor are added to terminate the reaction; 30-60 parts of diethylene glycol are then added to the trimer for prepolymerization, and the modified isocyanate is obtained by cooling.

5. The bio-based soft polyurethane foam according to claim 4, characterized in that: The antioxidant is one or more of antioxidant 1010 and antioxidant 168; and / or, The self-polymerization catalyst is one or more of tetramethylammonium hydroxide and 2,4,6-tris(dimethylaminomethyl)phenol; and / or, The polymerization inhibitor is o-toluenesulfonamide.

6. The bio-based soft polyurethane foam according to any one of claims 1 to 3 or 5, characterized in that: The catalyst is an amine catalyst; and / or, The foam stabilizer is silicone oil; and / or, The foaming agent is water.

7. The bio-based soft polyurethane foam according to any one of claims 1 to 3 or 5, characterized in that: The thickness of the bio-based soft polyurethane foam is 0.4-1.0 mm.

8. A method for preparing a bio-based soft polyurethane foam, for preparing the bio-based soft polyurethane foam according to any one of claims 1 to 7, characterized in that: The steps include: S1 prepares modified isocyanate; 100 parts of pentamethylene pentamethylene diisocyanate, 0.1-0.3 parts of antioxidant, and 0.05-0.2 parts of self-polymerization catalyst are mixed and subjected to self-polymerization reaction to generate trimer, and 0.1-0.5 parts of polymerization inhibitor are added to terminate the reaction; 30-60 parts of diethylene glycol are added to the trimer for prepolymerization reaction, and the mixture is cooled to obtain modified isocyanate; S2: mixing 10 to 40 parts of bio-based polyol, 60 to 90 parts of polyether polyol, 10 to 30 parts of foam stabilizer, 0.2 to 0.3 parts of foaming agent and 0.03 to 0.05 parts of catalyst to obtain a premix; S3: 40 to 60 parts of the modified isocyanate in S1 and the premix in S2 are mixed, and the mixture is coated on a base film for foaming to obtain the bio-based soft polyurethane foam.

9. The method for preparing bio-based soft polyurethane foam according to claim 8, characterized in that: The -NCO content of the trimer is 28% to 45%, and the -NCO content of the modified isocyanate is 15% to 30%.

10. The method for preparing bio-based soft polyurethane foam according to claim 8 or 9, characterized in that: In S1, the temperature of the self-polymerization reaction is 70-90°C and the time is 1-3 hours; the temperature of the pre-polymerization reaction is 50-90°C and the time is 1-3 hours; and / or, In S1, the self-polymerization reaction and the pre-polymerization reaction are both carried out under an inert atmosphere; and / or, in S1, the self-polymerization reaction and the pre-polymerization reaction are both carried out under stirring conditions; and / or, in S3, the foaming temperature is 80-100° C., and the foaming time is 10-15 min.

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