Adhesive Resins, Their Preparation Methods and Applications

Abstract

This invention belongs to the field of chemical materials and relates to an adhesive resin, its preparation method, and its application. The adhesive resin is prepared by polymerizing monomers such as N,N-dimethylacrylamide, methyl methacrylate, N,N-diethylaminoethyl methacrylate, and N-hydroxymethylacrylamide in a specific ratio. The resin is used to modify aramid fiber aerogel films. Through steps such as resin addition, acid treatment, neutralization, freeze-drying, and thermal crosslinking, the specific tensile strength and specific elongation at break of the film are significantly improved. This invention solves the problem of poor mechanical properties in existing aramid fiber aerogel films and provides an efficient and simple modification method with broad application prospects.

Description

Technical Field

[0001] This invention belongs to the field of chemical materials, and relates to adhesive resins, their preparation methods, and applications. Background Technology

[0002] Aramid fiber, short for polyphenylene phthalamide, is a high-performance fiber material with high modulus, high temperature resistance, corrosion resistance, low relative density, high strength, and good insulation. It is a synthetic aromatic polyamide fiber made from a linear polymer (at least 85% of the amide bonds are directly connected to two aromatic rings) formed by amide bonds linking aromatic rings (Ar-CONH-Ar). The main chain consists of aromatic rings and amide bonds, resulting in a highly rigid aromatic ring structure and an extended, rod-like polymer chain. This linear molecular chain structure also allows for high space utilization, enabling a large amount of polymer to be contained within a unit volume, thus resulting in high strength. Unlike ordinary flexible polymer chains, the main chain structure of para-aramid fiber is primarily composed of rod-like molecular structures formed by para-positioned benzene rings. Due to the presence of highly conjugated benzene rings, internal rotation of the molecular chain segments is difficult, resulting in a linear, rigid structure. Aramid fibers can be broadly classified into four types based on their molecular structure: poly(p-phenylene terephthalamide) (PPTA), isophthaloyl-m-phenylene diamine (PMIA), heterocyclic aromatic polyamide fibers containing heteroatoms, and ortho-aramid fibers (fully aromatic polyamide fibers). PPTA and PMIA are the most widely used. They are extensively applied in military, aerospace, electronics, transportation, construction, and medical fields.

[0003] Aramid fiber aerogel films possess excellent insulation, heat insulation, corrosion resistance, and other properties, as well as flame retardant, heat preservation, and noise reduction capabilities. Compared to inorganic silica aerogel materials, aramid fiber aerogel films exhibit better toughness and are less prone to breakage and particle formation under impact. However, the mechanical properties of aramid fiber aerogel films still limit their large-scale application, and improving their mechanical properties remains a challenge in this field. Therefore, this invention proposes a novel, environmentally friendly adhesive with good bonding strength and stable performance for the production of aramid fiber aerogel films, addressing the issue of low mechanical properties and demonstrating broad application prospects. Summary of the Invention

[0004] In view of this, the object of the present invention is to provide an adhesive resin and a method for preparing the same, as well as an aramid fiber aerogel film prepared using the adhesive resin and a method for preparing the same.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] This invention provides an adhesive resin, the chemical structural formula of which is shown in the figure below:

[0007]

[0008] Where x is the degree of polymerization of N,N-dimethylacrylamide (31-78), y is the degree of polymerization of methyl methacrylate (28-149), z is the degree of polymerization of N,N-diethylaminoethyl methacrylate (68-179), and m is the degree of polymerization of N-hydroxymethylacrylamide (53-155).

[0009] The adhesive resin has a molecular weight of 30,000-70,000.

[0010] The molecular weight of the adhesive resin is preferably 40,000-50,000.

[0011] The adhesive resin is formulated as follows by weight percentage: N-hydroxymethylacrylamide 3.2%–8.1%, N,N-dimethylacrylamide 2.5%–5.8%, methyl methacrylate 13.3%–16.6%, N,N-diethylaminoethyl methacrylate 6.5%–8.1%, propylene glycol monomethyl ether 62.7%, N,N-dimethylformamide 4.9%, azobisisovalerate (AIBN) 0.25%, with a solid content of 32.26%.

[0012] Furthermore, the preparation method of the adhesive resin includes the following steps:

[0013] S1: Raw material preparation: N-hydroxymethylacrylamide 3.2%–8.1%, N,N-dimethylacrylamide 2.5%–5.8%, methyl methacrylate 13.3%–16.6%, N,N-diethylaminoethyl methacrylate 6.5%–8.1%,

[0014] S2: Using AIBN as an initiator, prepare a 5% (w / w) N,N-dimethylformamide solution.

[0015] S3: The raw materials from step S1 and the initiator solution from step 2 are added to the reactor containing solvent in four batches at intervals of 10-15 minutes. The reaction temperature is 70-90℃, the reaction time is 5-10 hours, and the stirring speed is 300-450 rpm. The adhesive resin is obtained by solution free radical polymerization.

[0016] The solvent is a mixed solution of propylene glycol monomethyl ether and N,N-dimethylformamide, and the composition of the solvent solution by weight percentage is: propylene glycol monomethyl ether 46.4% to 92.7%, and dimethylformamide 7.3% to 53.6%.

[0017] Furthermore, the modified aramid fiber aerogel film is prepared using the adhesive resin.

[0018] The method for preparing the modified aramid fiber aerogel film involves directly adding the adhesive resin at 15.5% of the aramid fiber mass to the aramid fiber dispersion, then adding dilute hydrochloric acid or dilute sulfuric acid and stirring for 10-15 minutes to fully dissolve the polymer. After neutralizing the acid with sodium carbonate solution or sodium hydroxide solution, the polymer is uniformly precipitated. After filtration, the mixture is frozen for 8 hours, then freeze-dried for 24 hours, and finally thermally crosslinked in an oven at 100°C for 4 hours to obtain the modified aramid fiber aerogel film.

[0019] The beneficial effects of this invention are as follows: the obtained modified aramid fiber aerogel not only possesses the excellent properties of traditional aramid fiber aerogels, such as insulation, thermal insulation, and corrosion resistance, but also improves the flexural strength and mechanical properties of aramid fiber aerogels. The specific tensile strength of the modified aramid fiber aerogel film is increased by 22.22%-33.33%, and the specific elongation at break is increased by 1.15%-28.74%. The modified aramid fiber aerogel film prepared by this method has a low and controllable density, and has broad application prospects in the fields of thermal insulation, heat insulation, and sound insulation in construction, automobiles, and home appliances.

[0020] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0021] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein:

[0022] Figure 1 The stress-strain curve for Example 1;

[0023] Figure 2 The stress-strain curve for Example 2;

[0024] Figure 3 The stress-strain curve for Example 3;

[0025] Figure 4 The stress-strain curve for Example 4;

[0026] Figure 5 This is an image of the adhesive resin solution for the aramid fiber aerogel film in Example 1;

[0027] Figure 6The image shows the freeze-drying of the modified aramid fiber aerogel from Example 1 in a freeze dryer;

[0028] Figure 7 The image shows the thermal crosslinking of the modified aramid fiber aerogel in an oven in Example 1.

[0029] Figure 8 This is an image of the modified aramid fiber aerogel after thermal crosslinking in Example 1. Detailed Implementation

[0030] The following specific examples 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 be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0031] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures. They should not be construed as limiting the invention. To better illustrate the embodiments of the invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0032] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "front," and "rear" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present invention. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0033] Example 1

[0034] First, weigh 1g of N-hydroxymethylacrylamide, 1.8g of N,N-dimethylacrylamide, 5.12g of methyl methacrylate, 2g of N,N-diethylaminoethyl methacrylate, and 19.4g of propylene glycol monomethyl ether. Prepare a 5% (w / w) solution of azobisisovalerate (AIBN) in dimethylformamide as an initiator. React at 90℃ for 4h to obtain an adhesive resin for aramid fiber aerogel films.

[0035] Aramid fiber aerogel film

[0036] The raw materials, dosage and preparation method of aramid fiber dispersion are as follows: First, weigh 10g of poly(p-phenylene terephthalamide) precursor, add 50g of deionized water to fully wet it, and then disperse it dropwise in 250g of deionized water under the action of a high-shear homogenizing emulsifier for 4h to obtain aramid fiber dispersion.

[0037] Then, 1.55g of adhesive resin for the aramid fiber aerogel film was added to 310g of aramid fiber dispersion, followed by 7g of 9.8% dilute sulfuric acid and stirring for 10-15 minutes. Then, 10.9g of 5% sodium hydroxide solution was added and stirred for 10-15 minutes. 50g of the mixed dispersion was taken, filtered, and then frozen in a freezer for 8 hours. After freeze-drying for 24 hours, it was thermally crosslinked in an oven at 100℃ for 4 hours to obtain the modified aramid fiber aerogel film product.

[0038] Performance testing

[0039] The modified aramid fiber aerogel film product prepared above was cut into 10mm × 50mm strips. The thickness of the strips was measured using vernier calipers, and the mass was measured using an analytical balance to calculate the density. The strips were then tested on an electronic universal testing machine, and the tensile strength and elongation at break were recorded. The specific tensile strength (MPa·cm⁻¹) was obtained by dividing the tensile strength and elongation at break by the density. 3 / g) and specific elongation at break (%·cm) 3 / g). For example Figure 1 In the test, the sample had a tensile strength of 0.949 MPa, an elongation at break of 4.10%, and specific tensile strength and specific elongation at break of 0.022 MPa·cm. 3 / g, 0.094%·cm3 / g. At the same density, its tensile strength and toughness are superior to those of unmodified aramid fiber aerogel film.

[0040] Example 2

[0041] The raw materials, dosages, and preparation methods for the adhesive used to prepare aramid fiber aerogel films in this embodiment are as follows: First, 2g of N-hydroxymethylacrylamide, 1g of N,N-dimethylacrylamide, 4.42g of methyl methacrylate, 2.5g of N,N-diethylaminoethyl methacrylate, and 19.4g of propylene glycol monomethyl ether are weighed out, and 1.6g of a 5% (w / w) AIBN dimethylformamide solution is prepared as an initiator. The mixture is reacted at 90°C for 4 hours to obtain the adhesive for aramid fiber aerogel films.

[0042] The raw materials, dosages, and preparation methods for preparing the aramid fiber dispersion in this embodiment are as follows: First, 10g of poly(p-phenylene terephthalamide) precursor is weighed and fully soaked in 50g of deionized water. Then, it is dispersed dropwise in 250g of deionized water under the action of a high-shear homogenizing emulsifier for 5 hours to obtain the aramid fiber dispersion.

[0043] Then, 1.55g of adhesive was added to 310g of aramid fiber dispersion, followed by 8.4g of 9.8% dilute sulfuric acid and stirred for 10-15 minutes. Then, 12g of 5% sodium hydroxide solution was added and stirred for 10-15 minutes. 50g of the mixed dispersion was taken, filtered, and frozen in a freezer for 8 hours. After freeze-drying for 24 hours, it was thermally crosslinked in an oven at 100℃ for 4 hours to obtain the modified aramid fiber aerogel film product.

[0044] The modified aramid fiber aerogel film product prepared above was cut into 10mm × 50mm strips. The thickness of the strips was measured using vernier calipers, and the mass was measured using an analytical balance to calculate the density. The strips were then tested on an electronic universal testing machine, and the tensile strength and elongation at break were recorded. The specific tensile strength (MPa·cm⁻¹) was obtained by dividing the tensile strength and elongation at break by the density. 3 / g) and specific elongation at break (%·cm) 3 / g). For example Figure 2 In the test, the sample had a tensile strength of 0.951 MPa, an elongation at break of 4.49%, and specific tensile strength and specific elongation at break of 0.024 MPa·cm. 3 / g, 0.112%·cm3 / g. At the same density, its tensile strength and toughness are superior to those of unmodified aramid fiber aerogel film.

[0045] Example 3

[0046] The raw materials, dosages, and preparation methods for the adhesive used to prepare aramid fiber aerogel films in this embodiment are as follows: First, 2.5g of N-hydroxymethylacrylamide, 0.8g of N,N-dimethylacrylamide, 4.12g of methyl methacrylate, 2.5g of N,N-diethylaminoethyl methacrylate, and 19.4g of propylene glycol monomethyl ether were weighed, and 1.6g of a 5% (w / w) AIBN dimethylformamide solution was prepared as an initiator. The mixture was reacted at 90°C for 4 hours to obtain the adhesive for aramid fiber aerogel films.

[0047] The raw materials, dosages, and preparation methods for preparing the aramid fiber dispersion in this embodiment are as follows: First, 10g of poly(p-phenylene terephthalamide) precursor is weighed and fully soaked in 50g of deionized water. Then, it is dispersed dropwise in 250g of deionized water under the action of a high-shear homogenizing emulsifier for 4 hours to obtain the aramid fiber dispersion.

[0048] Then, 1.55g of adhesive for the aramid fiber aerogel film was added to 310g of aramid fiber dispersion, followed by 8g of 9.8% dilute sulfuric acid and stirring for 10-15 minutes. Then, 11.4g of 5% sodium hydroxide solution was added and stirred for 10-15 minutes. 50g of the mixed dispersion was taken, filtered, and then frozen in a freezer for 8 hours. After freeze-drying for 24 hours, it was thermally crosslinked in a 100℃ oven for 4 hours to obtain the modified aramid fiber aerogel film product.

[0049] The modified aramid fiber aerogel film product prepared above was cut into 10mm × 50mm strips. The thickness of the strips was measured using vernier calipers, and the mass was measured using an analytical balance to calculate the density. The strips were then tested on an electronic universal testing machine, and the tensile strength and elongation at break were recorded. The specific tensile strength (MPa·cm⁻¹) was obtained by dividing the tensile strength and elongation at break by the density. 3 / g) and specific elongation at break (%·cm) 3 / g). For example Figure 1 In the test, the sample had a tensile strength of 0.978 MPa, an elongation at break of 3.62%, and specific tensile strength and specific elongation at break of 0.024 MPa·cm. 3 / g, 0.088%·cm3 / g. At the same density, its tensile strength is better than that of unmodified aramid fiber aerogel film, and its toughness is slightly better than that of unmodified aramid fiber aerogel film.

[0050] Example 4

[0051] The raw materials, dosages, and preparation methods for preparing the aramid fiber dispersion in this comparative example are as follows: First, 10g of poly(p-phenylene terephthalamide) precursor was weighed and fully soaked in 50g of deionized water. Then, it was dispersed dropwise in 250g of deionized water under the action of a high-shear homogenizing emulsifier for 4 hours to obtain the aramid fiber dispersion.

[0052] Then, 50g of aramid fiber dispersion was filtered and frozen in a freezer for 8 hours, and then freeze-dried for 24 hours to obtain aramid fiber aerogel film product.

[0053] The aramid fiber aerogel film product prepared above was cut into 10mm × 50mm strips. The thickness of the strips was measured using vernier calipers, and the mass was measured using an analytical balance to calculate the density. The strips were then placed on an electronic universal testing machine for testing, and the tensile strength and elongation at break were recorded. The specific tensile strength (MPa·cm⁻¹) was obtained by dividing the tensile strength and elongation at break by the density. 3 / g) and specific elongation at break (%·cm) 3 / g).

[0054] The aramid fiber aerogel films prepared in Examples 1-3 and Example 4 were evaluated according to the following methods:

[0055] Tensile strength: The samples from Examples 1-3 and Example 4 were cut into 10mm × 50mm strips and tested on an electronic universal testing machine.

[0056] Table 1. Performance results of aramid fiber aerogels from Examples 1-3 and Example 4.

[0057]

[0058]

[0059] As can be seen from Table 1, the density of Example 4, which uses an adhesive for aramid fiber aerogel film without added aramid fiber, is 44 g / cm³. 3 The tensile strength is 0.812 MPa, the elongation at break is 3.86%, and the specific tensile strength and specific elongation at break are 0.018 and 0.087, respectively.

[0060] The raw material formulation and weight ratio of the adhesive used for the aramid fiber aerogel film in Example 1 are as follows: N-hydroxymethylacrylamide 3.2%, N,N-dimethylacrylamide 5.8%, methyl methacrylate 16.6%, N,N-diethylaminoethyl methacrylate 6.5%, propylene glycol monomethyl ether 62.7%, dimethylformamide 4.9%, AIBN 0.25%, with a solid content of 32.26%. The density of the modified aramid fiber aerogel film in Example 1 is 43 g / cm³. 3 The tensile strength and elongation at break were 0.949 MPa and 4.1%, respectively, and the specific tensile strength and specific elongation at break were 0.022 and 0.095, respectively, which were 22.22% and 14.94% higher than those of Comparative Example 1.

[0061] Compared to Example 1, Example 2 increased the weight percentage of N-hydroxymethylacrylamide in the adhesive raw material formulation for aramid fiber aerogel films from 3.2% to 6.4%, and the density was 40 g / cm³. 3 The tensile strength and elongation at break were 0.951 MPa and 4.49%, respectively, and the specific tensile strength and specific elongation at break were 0.024 and 0.112, respectively, which were 33.33% and 28.74% higher than those in Example 4.

[0062] Compared to Example 1, Example 3 increased the weight percentage of N-hydroxymethylacrylamide in the adhesive raw material formulation for aramid fiber aerogel films from 3.2% to 8.1%, and the density was 41 g / cm³. 3The tensile strength and elongation at break were 0.987 MPa and 3.62%, respectively, and the specific tensile strength and specific elongation at break were 0.024 and 0.088, respectively, which were 33.33% and 1.15% higher than those in Example 4.

[0063] As the weight percentage of N-hydroxymethylacrylamide in the raw materials increases, the tensile strength of the modified aramid fiber aerogel film continuously increases, while the elongation at break initially increases and then decreases.

[0064] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. An adhesive resin, characterized in that: The chemical structural formula of the adhesive resin is as follows: ， Where x is the degree of polymerization of N,N-dimethylacrylamide (31-78), y is the degree of polymerization of methyl methacrylate (28-149), z is the degree of polymerization of N,N-diethylaminoethyl methacrylate (68-179), and m is the degree of polymerization of N-hydroxymethylacrylamide (53-155).

2. The adhesive resin according to claim 1, characterized in that: The adhesive resin has a molecular weight of 30,000-70,000.

3. The adhesive resin according to claim 2, characterized in that: The adhesive resin has a molecular weight of 40,000-50,000.

4. The adhesive resin according to any one of claims 1-3, characterized in that: The adhesive resin is composed of the following mass percentages: N-hydroxymethylacrylamide 3.2%~8.1%, N,N-dimethylacrylamide 2.5%~5.8%, methyl methacrylate 13.3%~16.6%, N,N-diethylaminoethyl methacrylate 6.5%~8.1%, propylene glycol monomethyl ether 62.7%, N,N-dimethylformamide 4.9%, AIBN 0.25%, and a solid content of 32.26%.

5. The method for preparing the adhesive resin according to claim 4, characterized in that: The steps are as follows: S1: Raw material preparation: N-hydroxymethylacrylamide 3.2%~8.1%, N,N-dimethylacrylamide 2.5%~5.8%, methyl methacrylate 13.3%~16.6%, N,N-diethylaminoethyl methacrylate 6.5%~8.1%, S2: Using AIBN as an initiator, prepare a 5% (w / w) N,N-dimethylformamide solution. S3: The raw materials from step S1 and the initiator solution from step 2 are added to the reactor containing solvent in four batches at intervals of 10-15 minutes. The reaction temperature is 70-90℃, the reaction time is 5-10 hours, and the stirring speed is 300 rpm-450 rpm. The adhesive resin is obtained by solution free radical polymerization.

6. The method for preparing the adhesive resin according to claim 5, characterized in that: The solvent is a mixed solution of propylene glycol monomethyl ether and N,N-dimethylformamide, and the composition of the solvent solution by weight percentage is: propylene glycol monomethyl ether 46.4%~92.7%, N,N-dimethylformamide 7.3%~53.6%.

7. The modified aramid fiber aerogel film prepared by the adhesive resin according to claim 4.

8. The method for preparing the modified aramid fiber aerogel film according to claim 7, characterized in that: The adhesive resin was directly added to the aramid fiber dispersion at 15.5% of the aramid fiber mass. Then, dilute hydrochloric acid or dilute sulfuric acid was added and stirred for 10-15 minutes to fully dissolve the polymer. After neutralizing the acid with sodium carbonate solution or sodium hydroxide solution, the polymer was uniformly precipitated. After filtration, the polymer was frozen for 8 hours and then freeze-dried for 24 hours. Finally, it was thermally crosslinked in an oven at 100°C for 4 hours to obtain the modified aramid fiber aerogel film.

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