Siloxane-based azoamine chain extender as well as preparation method and application thereof

Abstract

The invention relates to a siloxane-based azo amine chain extender as well as a preparation method and application thereof, and the siloxane-based azo amine chain extender disclosed by the invention can be used together with isocyanate and biodegradable polyester polyol to produce related polyurethane products. Due to the special structural design of the chain extender, the chain extender can be used as a latent curing agent, so that the later rapid curing can be realized while the enough stability and operability are ensured, and the overall production efficiency and mechanical property of a single-component polyurethane product are improved. Meanwhile, in the degradation reaction process of the product, components for promoting the degradation reaction are continuously decomposed in the system, so that the degradability of the product is effectively improved, and the degradation speed of the product is increased. The product can be applied to the fields of polyurethane coatings, adhesives and the like.

Description

Technical Field

[0001] The present invention belongs to the field of polyurethanes, and specifically relates to a siloxanyl azoamine chain extender and its preparation method and application. Background Art

[0002] As a functional additive in the polyurethane system, the chain extender acts as a hard segment structure to extend the molecular chains of the polymer hard segments, generating linear molecules with a larger molecular weight and increasing the hard segment content, thereby playing a role in improving the overall mechanical properties of the product. Among them, amine chain extenders are an important type of chain extender. Because it can react with isocyanate to form urea bonds, it has excellent mechanical properties. At the same time, it has a high reactivity with isocyanate. Combining the above characteristics, it can be applied to fields such as polyurethane coatings, polyurethane elastomers, and polyurethane adhesives.

[0003] Polyurethane is a cross-linked three-dimensional structure polymer material obtained by the thermal curing reaction of isocyanate, polyester or polyether polyol. Polyurethane materials are widely used in many application fields due to their excellent properties. Polyurethane materials also have some problems to be solved. Polyurethane materials themselves are non-degradable and cannot be recycled after being discarded, causing "white pollution". The methods for treating polyurethane waste are mainly landfill and incineration, which will continuously cause different harms to the environment. Therefore, the development of environmentally friendly biodegradable polyurethane materials has become the key to the sustainable development of the industry in the future.

[0004] In recent years, the research on degradable polyurethanes has become a hot topic. Patent CN114989770A discloses a biodegradable bio-based polyurethane adhesive composition. By adding tannin-modified polyol, the phenolic ester groups in the tannin polyol are hydrolyzed to improve the soil environment and promote the hydrolysis of ester groups and amide groups in the system, realizing the degradation of polyurethane materials. However, only the polyol component in the system, that is, the soft segment part of the polyurethane, is degradable. There is still a large amount of non-degradable hard segment part, so the degradation effect of the whole system is limited. Patent CN113603852A provides a method for preparing biodegradable polyurethane, that is, a pendant chain is introduced into the chain extender to reduce the intermolecular force and lower the crystallinity inside the polyurethane system, so that microorganisms can more easily enter the system, promoting the degradation of the polyurethane system. However, it does not play a role in the degradation of the polyurethane structure itself. Summary of the Invention

[0005] The purpose of the present invention is to provide a siloxanyl azoamine chain extender. As a latent curing agent, this chain extender can stably exist in a one-component polyurethane system, while improving the curing efficiency and the mechanical properties of the product. In addition, the polyurethane product of this chain extender can also be guaranteed to decompose under the action of certain external conditions, and the degradation of the polyurethane hard segment can be solved through its own degradation.

[0006] Another object of the present invention is to provide a preparation method of such a siloxanyl azoamine chain extender.

[0007] Another object of the present invention is to provide the application of such a siloxanyl azoamine chain extender.

[0008] To achieve the above-mentioned invention objects, the technical solution of the present invention is as follows:

[0009] A siloxanyl azoamine chain extender, the structural formula of which is:

[0010]

[0011] Wherein R 1 is an alkyl group with 2 - 20 carbon atoms, preferably an alkyl group with 2 - 10 carbon atoms. Further, R 1 is preferably an alkyl group with 2 - 4 carbon atoms, more preferably any one of ethyl, propyl or butyl; R 2 is an aromatic ring or an alicyclic ring, and R 2 is preferably an alicyclic ring, such as any one of cyclohexyl and dicyclohexylmethane.

[0012] In some specific embodiments, the structure of the siloxanyl azoamine chain extender is as follows:

[0013]

[0014] Wherein, R 1 is an alkyl group with 2 - 20 carbon atoms. Further, R 1 is preferably an alkyl group with 2 - 4 carbon atoms, more preferably any one of ethyl, propyl or butyl.

[0015] On the other hand of the present invention, a preparation method of the aforementioned siloxanyl azoamine chain extender includes the step of adding an aliphatic diamine monomer, an aromatic or alicyclic diamine monomer, an end - amino siloxane monomer and a metal catalyst into a reactor to react and generate the siloxanyl azoamine chain extender.

[0016] In some specific embodiments, the aliphatic diamine monomer is selected from alkyl diamines with 2 - 20 carbon atoms, preferably any one of ethylenediamine, propylenediamine and hexamethylenediamine; and / or

[0017] the aromatic diamine monomer is selected from p - phenylenediamine; and / or

[0018] the alicyclic diamine monomer is selected from 4,4 - diamino - dicyclohexylmethane (HMDA) or 1,4 - cyclohexanediamine any one of them; and / or

[0019] The amino-terminated siloxane monomer is any one of 2-trimethoxysilylethylamine and 2-triethoxysilylethylamine.

[0020] In some specific embodiments, the molar ratio of the aliphatic diamine monomer, aromatic or alicyclic diamine monomer to the amino-terminated siloxane monomer is 1:1 to 5:1 to 5, such as 1:1:1, 1:3:5, 1:5:3, 1:5:5, 1:4:3, etc.

[0021] In some specific embodiments, the metal catalyst is selected from any one of zinc, bismuth, and tin, preferably zinc, and more preferably zinc powder. Among them, the metal catalyst is preferably added in the form of metal powder to increase the contact area of the catalyst, and zinc powder is preferred.

[0022] In some specific embodiments, the dosage of the metal catalyst is 0.1-1% of the sum of the weights of the aliphatic diamine monomer, aromatic or alicyclic diamine monomer, and amino-terminated siloxane monomer, such as 0.1%, 0.3%, 0.5%, 0.7%, 1%, etc.

[0023] In some specific embodiments, the reaction temperature of the reaction is 50-150 °C, such as 50 °C, 60 °C, 65 °C, 70 °C, 80 °C, 90 °C, 100 °C, 110 °C, 120 °C, 130 °C, 140 °C, etc., and the reaction time is 1-5 hours, such as 2 hours, 3 hours, 4 hours, etc.

[0024] In a specific embodiment, the preparation method includes adding the aliphatic diamine monomer, aromatic or alicyclic diamine monomer, amino-terminated siloxane monomer, and zinc powder catalyst to a reactor, and reacting at 50-150 °C for 1-5 hours to generate a siloxanyl azoamine.

[0025] The reaction equation of the aforementioned reaction is:

[0026]

[0027] wherein, R 1 and the definition of R2 are as described above.

[0028] In another aspect of the present invention, there is provided the use of the siloxanyl azoamine chain extender in the preparation of polyurethanes.

[0029] The siloxanyl azoamine chain extender of the present invention can be used alone or in combination with other chain extenders. After being mixed with polyethers and plasticizers, it is used as a curing agent component for producing polyurethane-related products, and the related products can be applied to fields such as polyurethane coatings and adhesives.

[0030] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0031] The present invention develops a siloxane-based azoamine chain extender, one end of which is an amine group and the other end is a siloxane group. Due to this special structure, the substance can be used as a latent curing agent in a single-component polyurethane system. Specifically, the reaction process is divided into two parts. First, after mixing with isocyanate, the amine group at one end reacts quickly with isocyanate to form a urea bond, completing the initial chain extension reaction. But at the same time, the siloxane group at the other end plays a blocking role, suspending the cross-linking reaction, avoiding the diamine / diol chain extender from causing the system to cross-link rapidly due to excessive activity, causing the viscosity to grow rapidly and gel, affecting the overall operability and stability. In the first stage of the chain extension reaction, due to the formation of urea bonds, the mechanical properties of the system can be effectively improved as a rigid structure. After it is brushed and exposed to the air in the second stage of chain extension, the water in the air reacts with the siloxane group in the system, and the macromolecular chains in the system are completely cross-linked in a short time, achieving a complete maturation effect, so that the product performance quickly reaches a higher level. Therefore, using this type of new chain extender as an enhanced latent curing agent can achieve rapid curing when used while ensuring system stability and significantly improving system performance, while avoiding the release of harmful substances such as formaldehyde when traditional ketimine latent curing agents are unblocked.

[0032] The azoamine structure of the present invention can be decomposed under certain external conditions (for example, under alkaline conditions, the azo bond breaks at an ambient temperature of 50°C to 70°C to generate two primary amine structures). That is, while the hard segment is decomposed in the manner of chain extender decomposition, the system is alkaline due to the presence of amine monomers, and the decomposition of polyester segments such as polylactic acid and polycaprolactone can be effectively promoted under alkaline conditions. While achieving the decomposition of the hard segment, it plays an effective role in promoting the degradation of the soft segment containing the polyester segment, thereby enhancing the overall degradation ability of the polyurethane product. DETAILED DESCRIPTION

[0033] The following examples will further illustrate the method provided by the present invention, but the present invention is not limited to the listed examples, and should also include any other known changes within the scope of the rights claimed by the present invention.

[0034] Some raw material sources:

[0035] HMDA, from Wanhua Chemical Group Co., Ltd.;

[0036] 1,4-cyclohexanediamine, purchased from Tosoh Chemical;

[0037] p-phenylenediamine, purchased from Tosoh Chemical;

[0038] Butanediamine was purchased from Tosoh Chemical;

[0039] Ethylenediamine was purchased from Tosoh Chemical;

[0040] Decanediamine, purchased from Tosoh Chemical;

[0041] Zinc Zn1910 catalyst, purchased from Umicore;

[0042] Bismuth Bi1610 catalyst, purchased from Umicore;

[0043] Tin T12 catalyst, purchased from Umicore;

[0044] 2-Trimethoxysilylethylamine (cas: 65644-31-7), purchased from Shenzhen ATO Chemical;

[0045] 2-Triethoxysilylethylamine (cas: 45074-31-5), purchased from Shenzhen ATO Chemical;

[0046] Ketimine latent curing agent ALT-403, purchased from Changzhou Elite.

[0047] MDI-based one-component coating: 270 g of C2020 polyether, 550 g of F3135 polyether, and 500 g of 400-mesh calcium carbonate were stirred for 30 min and then dehydrated at 105 °C for 2 h. After cooling to 83 °C, 188 g of MDI50 was added for polymerization reaction to produce the MDI-based one-component coating. Both the polyether and MDI50 were from Wanhua Chemical Group Co., Ltd.

[0048] Other raw materials not specifically described in the examples of the present invention can be directly purchased from the market.

[0049] Example 1

[0050] (1) 1 mol of ethylenediamine, 1 mol of HMDA, and 1 mol of 2-trimethoxysilylethylamine were jointly added to a dry reactor, and 0.03 mol of zinc 1910 catalyst was added. The reaction was carried out at 50 °C for 1 h. After rectification, a siloxanyl azoamine was prepared.

[0051] (2) 8 g of the latent curing agent prepared in step (1) was added to 100 g of the MDI-based one-component coating and mixed and stirred for 30 min to ensure uniform dispersion therein.

[0052] According to the requirements of GB / T 19250-2013, it was applied in two coats at room temperature, and finally a standard mechanical property test specimen with a thickness of 2.5 mm was prepared. The surface drying could be achieved after 1 h. After curing at room temperature for 7 days, the mechanical properties were tested. Through a universal tensile machine, the test was carried out within the tensile speed range required by the national standard, and the tensile shear strength of the specimen could reach 6.3 Mpa, and the elongation at break could reach 558%.

[0053] Degradation test: Cut small sample blocks of 10 mm × 10 mm × 5 mm on the sample plate, immerse them in 25 ml of phosphate buffer solution (pH value = 7.2), place them in an environment of 37 ± 1 °C, take them out every 6 - 7 days, dry them to constant weight in a vacuum at 80 °C and then weigh them, and calculate the percentage of mass reduction. After soaking for 20 days, the weight loss rate reaches 15.9%.

[0054] Example 2

[0055] (1) Add 1 mol of ethylenediamine, 5 mol of HMDA, and 5 mol of 2-trimethoxysilylethylamine together to a dry reactor, add 0.011 mol of zinc 1910 catalyst, and react at a temperature of 150 °C for 5 hours. After rectification, a siloxanyl azoamine is prepared.

[0056] (2) Add 8 g of the latent curing agent prepared in step (1) to 100 g of the MDI-based one-component coating and mix and stir for 30 min to ensure uniform dispersion therein.

[0057] According to the requirements of national standard GBT19250-2013, apply it in two times at room temperature, and finally obtain a standard mechanical property test sample piece with a thickness of 2.5 mm. The surface can dry in 1 hour. After curing at room temperature for 7 days, conduct mechanical property tests. Through a universal tensile machine, test within the tensile speed range required by the national standard, and the tensile shear strength of the sample can reach 7.3 Mpa, and the elongation at break can reach 600%.

[0058] Degradation test: Cut small sample blocks of 10 mm × 10 mm × 5 mm on the sample plate, immerse them in 25 ml of phosphate buffer solution (pH value = 7.2), place them in an environment of 37 ± 1 °C, take them out every 6 - 7 days, dry them to constant weight in a vacuum at 80 °C and then weigh them, and calculate the percentage of mass reduction. After soaking for 20 days, the weight loss rate reaches 16.8%.

[0059] Example 3

[0060] (1) Add 2 mol of propylenediamine, 5 mol of 1,4-cyclohexanediamine, and 5 mol of 2-trimethoxysilylethylamine together to a dry reactor, add 0.06 mol of tin T12 catalyst, and react at a temperature of 100 °C for 3 hours. After rectification, a siloxanyl azoamine is prepared.

[0061] (2) Add 8 g of the latent curing agent prepared in step (1) to 100 g of the MDI-based one-component coating and mix and stir for 30 min to ensure uniform dispersion therein.

[0062] According to the requirements of national standard GBT19250-2013, it is applied in two coats at room temperature, and finally a standard mechanical property test sample with a thickness of 2.5 mm is obtained. The surface can be dried in 1 hour. After curing at room temperature for 7 days, the mechanical property test is carried out. Through a universal tensile machine, the test is carried out within the tensile speed range required by the national standard. The tensile shear strength of the sample can reach 6.5 Mpa, and the elongation at break can reach 572%.

[0063] Degradation test: Cut a small sample block of 10 mm×10 mm×5 mm on the sample plate, immerse it in 25 ml of phosphate buffer solution (pH value = 7.2), place it in an environment of 37±1℃, take it out every 6-7 days, dry it in vacuum at 80℃ until constant weight, and then weigh it to calculate the percentage of mass reduction. After soaking for 20 days, the weight loss rate reaches 16.0%.

[0064] Example 4

[0065] (1) Add 2 mol of butanediamine, 4 mol of 1,4-cyclohexanediamine, and 6 mol of 2-trimethoxysilylethylamine to a dry reactor, add 0.1 mol of bismuth 1610 catalyst, and react at 80℃ for 4 hours. After rectification, a siloxanyl azoamine is obtained.

[0066] (2) Add 8 g of the latent curing agent prepared in step (1) to 100 g of MDI-based one-component coating and mix and stir for 30 min to ensure uniform dispersion.

[0067] According to the requirements of national standard GBT19250-2013, it is applied in two coats at room temperature, and finally a standard mechanical property test sample with a thickness of 2.5 mm is obtained. The surface can be dried in 1 hour. After curing at room temperature for 7 days, the mechanical property test is carried out. Through a universal tensile machine, the test is carried out within the tensile speed range required by the national standard. The tensile shear strength of the sample can reach 6.1 Mpa, and the elongation at break can reach 610%.

[0068] Degradation test: Cut a small sample block of 10 mm×10 mm×5 mm on the sample plate, immerse it in 25 ml of phosphate buffer solution (pH value = 7.2), place it in an environment of 37±1℃, take it out every 6-7 days, dry it in vacuum at 80℃ until constant weight, and then weigh it to calculate the percentage of mass reduction. After soaking for 20 days, the weight loss rate reaches 15.3%.

[0069] Example 5

[0070] (1) Add 2 mol of sebac diamine, 6 mol of p-phenylenediamine, and 8 mol of 2-triethoxysilylethylamine to a dry reactor, add 0.08 mol of tin T12 catalyst, and react at 70℃ for 3.5 hours. After rectification, a siloxanyl azoamine is obtained.

[0071] (2) Add 8 g of the latent curing agent prepared in step (1) to 100 g of the one-component MDI-based coating, and mix and stir for 30 min to ensure uniform dispersion therein.

[0072] According to the requirements of national standard GBT19250-2013, apply two coats at room temperature to finally obtain a standard mechanical property test sample with a thickness of 2.5 mm. Surface drying can be achieved after 1 hour. After curing at room temperature for 7 days, conduct mechanical property tests. Through a universal tensile testing machine, test within the tensile speed range required by the national standard. The tensile shear strength of the sample can reach 5.9 Mpa, and the elongation at break can reach 670%.

[0073] Degradation test: Cut small sample blocks with dimensions of 10 mm × 10 mm × 5 mm from the sample board, immerse them in 25 ml of phosphate buffer solution (pH value = 7.2), place them in an environment of 37 ± 1 °C, take them out every 6 - 7 days, dry them to constant weight in a vacuum at 80 °C and then weigh them to calculate the percentage reduction in mass. After soaking for 20 days, the weight loss rate reaches 15.6%.

[0074] Comparative example

[0075] Add 8 g of the ketimine latent curing agent to 100 g of the one-component MDI-based coating. After stirring and mixing thoroughly for 30 min, according to the requirements of national standard GBT19250-2013, apply two coats at room temperature to obtain a standard mechanical property test sample with a thickness of 2.5 mm. Surface drying has not occurred even after 3 hours. After curing at room temperature for 7 days, conduct mechanical property tests. Through a universal tensile testing machine, test within the tensile speed range required by the national standard. The tensile shear strength of the sample can reach 5.5 Mpa, and the elongation at break can reach 520%.

[0076] Degradation test: Cut small sample blocks with dimensions of 10 mm × 10 mm × 5 mm from the sample board, immerse them in 25 ml of phosphate buffer solution (PH value = 7.2), place them in an environment of 37 ± 1 °C, take them out every 6 - 7 days, dry them to constant weight in a vacuum at 80 °C and then weigh them to calculate the percentage reduction in mass. After soaking for 20 days, the weight loss rate is 1.26%.

[0077] It can be seen from this that the siloxanyl azoamine chain extender of the present invention contains a terminal primary amine group, and the primary amine group can react with isocyanate to form rigid urea bonds, which significantly improve the mechanical properties such as tensile strength and hardness of polyurethane products. The siloxanyl group at the other end can stably exist in the system, preventing the complete cross-linking of macromolecular chains in the system, making this chain extender exist as a latent curing agent in the system, and at the same time ensuring good stability can be maintained for a long time before use. When it is painted, the siloxanyl group in it quickly undergoes a cross-linking reaction upon contact with water in the air, causing the system to quickly set and cure. This greatly improves the construction efficiency. This kind of latent curing agent realizes stable existence in a one-component polyurethane system while improving the curing efficiency and the mechanical properties of the product. The polyurethane product of this chain extender can also be guaranteed to decompose under the action of certain external conditions. Since the chain extender belongs to the hard segment part of polyurethane, the degradation problem of the polyurethane hard segment can be solved through its own degradation; the alkanolamine monomer decomposed during its degradation can effectively promote the decomposition of the polyester polyol existing in the system due to its own alkalinity, so that effective degradation can be achieved in both the hard and soft segments, improving the overall degradation ability of polyurethane products.

Claims

1. A siloxanyl azoamine chain extender, characterized in that, its structural formula is: Among them, R 1 is an alkyl group having 2 to 20 carbon atoms, and R 2 is an aromatic ring or an alicyclic ring.

2. The siloxanyl azoamine chain extender according to claim 1, characterized in that, R 1 is an alkyl group having 2 to 10 carbon atoms, preferably an alkyl group having 2 to 4 carbon atoms; R 2 is an alicyclic ring.

3. The siloxanyl azoamine chain extender according to claim 2, characterized in that, The R 1 is selected from any one of ethyl, propyl or butyl; R 2 is any one of cyclohexyl and dicyclohexylmethane.

4. A preparation method of the siloxanyl azoamine chain extender according to any one of claims 1 to 3, characterized in that, it includes the step of adding an aliphatic diamine monomer, an aromatic or alicyclic diamine monomer, an amino-terminated siloxane monomer and a metal catalyst into a reactor to react and generate the siloxanyl azoamine chain extender.

5. The preparation method according to claim 4, characterized in that, the aliphatic diamine monomer is selected from C2-C20 alkyl diamines, preferably any one of ethylenediamine, propylenediamine and hexamethylenediamine; and / or the aromatic diamine monomer is selected from p-phenylenediamine; and / or The alicyclic diamine monomer is selected from any one of 4,4-diaminodicyclohexylmethane or 1,4-cyclohexanediamine ; and / or the amino-terminated siloxane monomer is any one of 2-trimethoxysilylethylamine and 2-triethoxysilylethylamine.

6. The preparation method according to claim 5, characterized in that, the molar ratio of the aliphatic diamine monomer, the aromatic or alicyclic diamine monomer to the amino-terminated siloxane monomer is 1:1 to 5:1 to 5.

7. The preparation method according to any one of claims 4 to 6, characterized in that, the metal catalyst is selected from any one of zinc, bismuth and tin, preferably zinc, and more preferably zinc powder.

8. The preparation method according to claim 7, characterized in that, the dosage of the metal catalyst is 0.1-1% of the sum of the weights of the aliphatic diamine monomer, the aromatic or alicyclic diamine monomer and the amino-terminated siloxane monomer.

9. The preparation method according to any one of claims 4 to 8, characterized in that, the reaction temperature is 50-150 °C and the reaction time is 1-5 hours.

10. Use of the siloxanyl azoamine chain extender according to any one of claims 1 to 3 or the siloxanyl azoamine chain extender according to any one of claims 4 to 9 in the preparation of polyurethanes.

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