Underwater adhesive as well as preparation method and application thereof

Abstract

The invention provides an underwater adhesive as well as a preparation method and application thereof, and belongs to the technical field of adhesives. The adhesive comprises the following components in parts by weight: 1 part of polyethyleneimine; 1-5 parts of acrylic acid; 0.1 to 30 parts of an acrylate monomer; and 0.01 to 1.75 parts of a photoinitiator. The adhesive disclosed by the invention is cured under ultraviolet irradiation, the curing time can be shortened, and the adhesive has excellent adhesive strength.

Description

Technical Field

[0001] The present invention belongs to the technical field of adhesives, and in particular relates to an underwater adhesive and a preparation method and application thereof. Background Art

[0002] Most adhesives on the market can only form permanent or reversible bonds with dry solid surfaces in air. With the rapid development of modern adhesive materials, the marine industry and underwater construction fields urgently need to develop underwater adhesives that can spread, bond, and cure underwater. Some new underwater adhesives have been developed, such as the use of crown ether-based host-guest chemistry or the introduction of ionic liquids to provide electrostatic interactions or cation-π interactions to prepare self-healing underwater tapes, and the introduction of catechol molecules to mimic the adhesion mechanism of mussels to achieve underwater adhesion. However, these underwater adhesives still have some problems that need to be overcome. For example, underwater adhesives obtained by imitating mussels are easily oxidized, resulting in a decrease in adhesion and reduced adhesion strength. In addition, the interior of many underwater adhesives is easily eroded by water, which can also lead to poor bonding performance. In addition, long curing times and the use of organic solvents may also hinder the practical application of these adhesives.

[0003] Prior art discloses a polythiazolidone (PTK) multi-weather-resistant underwater super-strong adhesive. The adhesive comprises, by weight, 96.7-96.9% polythiazolidone prepolymer, 1.31-1.54% glass fiber, 1.31-1.54% graphite powder, and 0.28-0.67% iron powder. The adhesive is applied underwater to the substrate surface, cold-pressed for 3-5 hours, and then left to cure for 7-18 hours. However, the curing time of this underwater adhesive is too long, hindering its practical application.

[0004] Prior art also discloses a wet / dry dual-use semi-interpenetrating polymer network pressure-sensitive adhesive (PSNA) composed of a linear polymer and a cross-linked network polymer, each of which is obtained by polymerizing a first monomer and a second monomer; the first monomer includes one or more of butyl acrylate, ethyl acrylate, and isooctyl acrylate, and the second monomer includes one or more of acrylic acid, acrylamide, and hydroxypropyl methacrylate. However, the underwater bonding strength of this PSA remains to be further improved. Summary of the Invention

[0005] The primary purpose of the present invention is to overcome the shortcomings and deficiencies of existing adhesives, such as long curing times and low underwater bond strength. The present invention provides an adhesive comprising polyethyleneimine, acrylic acid, an acrylate monomer, and a photoinitiator. The adhesive has a short curing time and exhibits excellent bond strength both in air and underwater.

[0006] Another object of the present invention is to provide a method for preparing the adhesive.

[0007] Another object of the present invention is to provide a use of the adhesive.

[0008] The above-mentioned purpose of the present invention is achieved through the following technical solutions: An adhesive comprising the following components in parts by weight: 1 part of polyethyleneimine; 1-5 parts of acrylic acid; 0.1-30 parts of acrylate monomer; Photoinitiator 0.01-1.75 parts; The structural formula of the acrylate monomer is shown in Formula I below:

[0009] Formula I In Formula I, R is -C n H 2n+1 , isobornyl or benzyl, n is 6 to 13; X is H or -CH3.

[0010] The reaction principle of the adhesive of the present invention is as follows: Polyethyleneimine is a polyelectrolyte containing numerous amino groups. Polyethyleneimine can serve as a template, allowing the numerous amino groups of polyethyleneimine to form dense, high-energy salt-bridge hydrogen bonds with the carboxyl groups of acrylic acid through non-covalent self-assembly. During use, a free radical polymerization reaction between acrylic acid and acrylate monomers is initiated by light, resulting in a structure containing a polymer mixture of polyacrylic acid-acrylate and polyethyleneimine. The adhesive of the present invention significantly increases the curing rate and shortens the curing time under light initiation. During the curing process, the adhesive of the present invention can achieve curing without the need for any solvent.

[0011] Since the acrylic ester of the specific structure of the present invention is a hydrophobic functional monomer, it is beneficial for the adhesive to remove interfacial water during underwater bonding, hindering water molecules from eroding the interior of the adhesive, while reducing the influence of the hydration layer on interfacial adhesion, thereby improving the adhesive strength underwater.

[0012] The preparation method of the solvent-free adhesive of the present invention is applicable to a variety of common acrylate hydrophobic monomers, has good universality, and has wide application value.

[0013] The invention adopts a solvent-free one-step method to prepare the adhesive, the raw materials are easily available, the preparation process is simple, the operation is easy, and the pollution to the environment by solvents and complex chemical cross-linking steps is avoided.

[0014] The solvent-free adhesive of the present invention is suitable for a variety of common adhesive bases. The prepared adhesive can exhibit excellent underwater bonding strength on different substrates, has good universality in adhesive preparation, and has stronger bonding performance in the air. It has wide application value and good production prospects.

[0015] Preferably, the acrylic acid ester monomer is one or more of hexyl acrylate (CAS No. 2499-95-8), n-heptyl methacrylate (CAS No. 5459-37-0), n-octyl acrylate (CAS No. 2499-59-4), isooctyl acrylate (CAS No. 103-11-7), 2-methyl-2-nonyl acrylate (CAS No. 2696-43-7), decyl acrylate (CAS No. 2156-96-9), undecyl methacrylate (CAS No. 16493-35-9), dodecyl acrylate (CAS No. 2156-97-0), isobornyl acrylate (CAS No. 5888-33-5) or benzyl acrylate (CAS No. 2495-35-4).

[0016] More preferably, the acrylate monomer is one or more of n-octyl acrylate, isooctyl acrylate, dodecyl acrylate, isobornyl acrylate or benzyl acrylate.

[0017] More preferably, the acrylate monomer is one or more of isooctyl acrylate, isobornyl acrylate or benzyl acrylate.

[0018] Preferably, the polyethyleneimine is one or more of branched polyethyleneimine and linear polyethyleneimine.

[0019] More preferably, the polyethyleneimine is a branched polyethyleneimine.

[0020] The branched structure of polyethyleneimine gives it abundant interaction sites, which is not only conducive to the formation of a high-density hydrogen bond network inside the polymer adhesive and enhances the cohesive strength of the polymer, but also helps to regulate the external interaction between the polymer adhesive and the substrate, improve the interfacial adhesion between the adhesive and the substrate, and thus improve the overall bonding performance of the adhesive.

[0021] Preferably, the photoinitiator is one or more of benzophenone, 2,2-diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropanone or 1-hydroxycyclohexylphenyl ketone.

[0022] Preferably, the number average molecular weight of the polyethyleneimine is 5,000-70,000.

[0023] More preferably, the number average molecular weight of the polyethyleneimine is 8,000-30,000.

[0024] The number average molecular weight of polyethyleneimine is larger, which is beneficial to enhancing the cohesive force of the adhesive.

[0025] More preferably, the amount of the photoinitiator used is 0.2-1% of the total mass of acrylic acid and acrylate monomers.

[0026] The present invention also protects a method for preparing the adhesive, comprising the following steps: mixing the components to obtain the adhesive.

[0027] The present invention also protects the use of the above-mentioned adhesive as an underwater adhesive in the fields of marine industry and underwater construction.

[0028] Preferably, the application includes the following steps: mixing polyethyleneimine, acrylic acid, acrylate monomer and photoinitiator, coating the mixture on the surface of substrate A, covering substrate A with substrate B, irradiating substrate A and / or substrate B with ultraviolet light, and bonding substrate A and substrate B; wherein at least one of substrate A or substrate B is a transparent substrate.

[0029] In practical applications, polyethyleneimine, acrylic acid, acrylate monomers, and an initiator are first added to a reaction vessel and stirred at room temperature to produce an adhesive precursor liquid. The precursor liquid is then applied to the surface of a common substrate, pressed against another transparent substrate, and irradiated with ultraviolet light to induce polymerization of the adhesive precursor liquid. After the reaction is complete, the two substrates are bonded together.

[0030] Wherein, the transparent substrate is one or more of glass, polymethyl methacrylate, polyethylene terephthalate, and polystyrene.

[0031] The common substrate includes one or more of polymethyl methacrylate, glass, aluminum sheet, copper sheet, stainless steel, polyethylene terephthalate, polystyrene, epoxy resin board, and wood.

[0032] Preferably, the ultraviolet light irradiation time is 2-2000 s.

[0033] When the bonding area is larger or the thickness of the transparent substrate to be bonded is thicker, the UV irradiation time can be appropriately increased.

[0034] More preferably, the ultraviolet light irradiation time is 10-200 s.

[0035] Preferably, the light power density of the ultraviolet light source used is 2-100 mW / cm 2 .

[0036] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides an adhesive comprising polyethyleneimine, acrylic acid, an acrylate monomer with a specific structure, and a photoinitiator. During use, under ultraviolet light, the acrylic acid, the acrylate monomer with a specific structure, and the photoinitiator undergo a polymerization reaction to form a structure comprising a polymer mixture of polyacrylic acid-acrylate and polyethyleneimine. The adhesive of the present invention has a shortened curing time and excellent underwater bond strength. After 10 seconds of ultraviolet light exposure, the adhesive exhibits an underwater shear strength exceeding 9 MPa against a glass substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 Schematic diagram of the reaction process of the adhesive in Example 1.

[0038] Figure 2 This is the hydrogen nuclear magnetic resonance spectrum of the adhesive in Example 1.

[0039] Figure 3 This is the infrared spectrum of the adhesive of Example 1. DETAILED DESCRIPTION

[0040] In order to more clearly and completely describe the technical solution of the present invention, the present invention is further described in detail through specific embodiments below. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. Various changes can be made within the scope of the rights of the present invention.

[0041] Branched polyethyleneimine, manufactured by Aladdin, with a brand name of 408727, and a number average molecular weight of 25,000.

[0042] Example 1 An adhesive comprises the following components in parts by weight: branched polyethyleneimine (1g), acrylic acid (5g), isooctyl acrylate (5g), and 2,2-diethoxyacetophenone photoinitiator (0.1g).

[0043] Example 2 An adhesive comprises the following components in parts by weight: branched polyethyleneimine (1g), acrylic acid (5g), benzyl acrylate (5g), and 2,2-diethoxyacetophenone photoinitiator (0.1g).

[0044] Example 3 An adhesive comprises the following components in parts by weight: branched polyethyleneimine (1g), acrylic acid (5g), isobornyl acrylate (5g), and 2,2-diethoxyacetophenone photoinitiator (0.1g).

[0045] Example 4 An adhesive comprises the following components in parts by weight: linear polyethyleneimine (1g), acrylic acid (5g), isooctyl acrylate (5g), and 2,2-diethoxyacetophenone photoinitiator (0.1g).

[0046] Comparative Example 1 An adhesive comprises the following components, measured in parts by weight: branched polyethyleneimine (1 g), acrylic acid (5 g), and a 2,2-diethoxyacetophenone photoinitiator (0.05 g).

[0047] The difference from Example 1 is that isooctyl acrylate is not added.

[0048] Comparative Example 2 An adhesive comprises the following components, measured in parts by weight: acrylic acid (5 g), benzyl acrylate (5 g), and 2,2-diethoxyacetophenone photoinitiator (0.1 g).

[0049] The difference from Example 2 is that no branched polyethyleneimine is added.

[0050] Performance Testing (1) Lap shear test: Refer to the standard ASTM F2255-05 (2015), make appropriate modifications on this basis, and conduct lap shear tests. The specific method is: cut a substrate sample with a specification of 10mm×40mm×2mm, take an appropriate amount of adhesive and apply it to a common substrate underwater or in air, with the coating area of ​​10mm×2.5mm. Press it with another transparent substrate, and irradiate the transparent substrate with 40mW ultraviolet light with a wavelength of 365nm for 10s to induce free radical polymerization (the reaction process diagram of the adhesive in Example 1 is shown in Figure 1). Figure 1 Then, the sample to be tested was subjected to a lap shear test at a rate of 5 mm / min using a tensile testing machine until the two bonded substrates broke at the bonding point, and the maximum load F during this process was recorded. max , each sample was repeated three times.

[0051] Calculation of lap shear strength: τ=Fmax / S Where τ is the lap shear strength (unit: MPa), F max is the maximum load (unit: N), S is the bonding area (unit: mm 2 ).

[0052] (1) The adhesives obtained in Examples 1 to 4 and Comparative Examples 1 to 2 were used to prepare lap shear test specimens in water and air, and lap shear tests were performed to obtain the test results shown in Table 1.

[0053] Wherein, the above-mentioned transparent substrate and common substrate to be bonded are both glass.

[0054] Table 1

[0055] (2) The adhesive obtained in Example 1 was used to prepare lap shear test specimens for lap shear testing, both underwater and in air. The transparent substrate to be bonded was glass, and commonly used substrates included various aluminum sheets, copper sheets, stainless steel, glass, epoxy resin boards, and wood. The test results are shown in Table 2.

[0056] Table 2

[0057] As shown in Table 1, there is a significant difference in the shear strength of Example 1 and Comparative Examples 1-2 when bonding glass substrates underwater. Compared to the adhesives of Comparative Examples 1-2, the adhesives of the present invention significantly improve the shear strength of the glass substrates underwater after 10 seconds of UV irradiation, reaching 9.31 MPa to 13.2 MPa. Among them, the adhesive of Example 1 achieves a shear strength of 13.2 MPa underwater on the glass substrate, demonstrating excellent underwater bonding performance. The adhesives prepared in Examples 2 and 3, which replace the isooctyl acrylate monomer with benzyl acrylate or isobornyl acrylate, show some differences in underwater bonding performance, but both exhibit higher underwater shear strength than Comparative Examples 1-2, indicating that the preparation strategy of the solvent-free adhesive of the present invention is applicable to a variety of common hydrophobic acrylate monomers and has good universality in adhesive preparation. In Example 4, the adhesive prepared by replacing branched polyethyleneimine with linear polyethyleneimine has a slightly lower underwater shear strength than that of Example 1, indicating that the branched structure in polyethyleneimine is conducive to the formation of dense high-binding energy salt bridge hydrogen bonds inside the adhesive, which can obtain better underwater bonding performance.

[0058] Table 2 shows that Example 1 exhibits different shear strengths for bonding glass substrates both underwater and in air. The adhesive formulated with branched polyethyleneimine and isooctyl acrylate not only exhibits high shear strength for a variety of substrates underwater, but also exhibits even higher shear strengths for various substrates in air. The underwater shear strengths exceed 10 MPa, while the shear strengths in air exceed 16 MPa.

[0059] (II) After the adhesive of Example 1 was irradiated with 40 mW ultraviolet light of 365 nm wavelength for 10 s to induce free radical polymerization, the structure of the obtained adhesive layer was characterized by nuclear magnetic resonance hydrogen spectroscopy. Figure 2 The obtained adhesive layer was characterized by infrared spectroscopy, as shown in Figure 3 As shown. Figure 2 and Figure 3It can be seen that in the chemical shift range of 6 to 7, the proton peaks attributed to the double bonds of acrylic acid and isooctyl acrylate disappear, indicating that the reaction is complete and the adhesive is completely cured.

[0060] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. An adhesive, characterized in that Calculated by weight, it includes the following components: 1 part of polyethyleneimine; 1-5 parts of acrylic acid; 0.1-30 parts of acrylate monomer; Photoinitiator 0.01-1.75 parts; The structural formula of the acrylic acid ester monomer is shown in the following formula I: Formula I In Formula I, R is -C n H 2n+1 , isobornyl or benzyl, n is 6 to 13; X is H or -CH3.

2. The adhesive according to claim 1, characterized in that The acrylate monomer is one or more of n-octyl acrylate, isooctyl acrylate, dodecyl acrylate, isobornyl acrylate or benzyl acrylate.

3. The adhesive according to claim 1, characterized in that The polyethyleneimine is one or more of branched polyethyleneimine and linear polyethyleneimine.

4. The adhesive according to claim 1, characterized in that The photoinitiator is one or more of benzophenone, 2,2-diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropanone or 1-hydroxycyclohexylphenyl ketone.

5. The adhesive according to claim 1, characterized in that The number average molecular weight of the polyethyleneimine is 5,000-70,000.

6. The method for preparing the adhesive according to any one of claims 1 to 5, characterized in that: The method comprises the following steps: mixing various components to obtain the adhesive.

7. Use of the adhesive according to any one of claims 1 to 5 as an underwater adhesive in the fields of marine industry and underwater construction.

8. The application according to claim 7, characterized in that: The method comprises the following steps: mixing polyethyleneimine, acrylic acid, acrylate monomer and photoinitiator, coating the mixture on the surface of substrate A, covering substrate A with substrate B, irradiating substrate A and / or substrate B with ultraviolet light, and bonding substrate A and substrate B; wherein at least one of substrate A or substrate B is a transparent substrate.

9. The application according to claim 8, characterized in that: The transparent substrate is one or more of glass, polymethyl methacrylate, polyethylene terephthalate, and polystyrene.

10. The use according to claim 8, characterized in that The ultraviolet light irradiation time is 2-2000 s.

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