A uv hydrolysis glue and a preparation method thereof

Abstract

This application relates to the field of adhesives, and more specifically, to a UV hydrolyzable adhesive and its preparation method. It comprises the following raw materials by weight percentage: 40-58% modified polyurethane acrylate, 10-20% tackifier and absorbent polymer, 1-3% photoinitiator, and the balance being an active diluent; the tackifier and absorbent polymer is composed of a polyurethane associative thickener, methanol-etherified melamine-formaldehyde resin, absorbent fibers, and hydroxyl acrylate. By specifically selecting the polyurethane associative thickener, methanol-etherified melamine-formaldehyde resin, absorbent fibers, and hydroxyl acrylate as the main components of the tackifier and absorbent polymer, and optimizing their ratio, the adhesion strength and hydrolysis detachment effect of the UV hydrolyzable adhesive on the surfaces of lightweight composite materials such as carbon fiber composites and glass fiber reinforced plastics are significantly improved.

Description

Technical Field

[0001] This application relates to the field of adhesives, and more specifically, to a UV hydrolyzed adhesive and a method for preparing the same. Background Technology

[0002] UV hydrolyzable adhesives, as a special type of UV-curable adhesive, are gradually emerging in the industrial field. Their core advantage lies in their rapid curing under UV irradiation, forming a high-strength bond. Simultaneously, under specific conditions (such as hydrolysis), the bond strength can be reduced by treatment with water or specific aqueous solutions, thereby enabling the separation of bonded components. This unique property has led to their widespread application in fields such as electronics, medical devices, optics, and automobiles. With the development of new energy vehicles, their application in lightweight composite material bonding has been further promoted. However, despite the significant value of UV hydrolyzable adhesives due to their rapid curing, high bond strength, and easy separation without residue, their applicability to various material surfaces still faces challenges.

[0003] To improve the adhesive performance of UV hydrolyzed adhesives, existing technologies typically employ the following methods: first, compounding and optimizing various polyester polyols, then introducing epoxy-containing monomers to enhance adhesion and improve the adhesive's basic properties; second, adding tackifiers to strengthen the adhesion between the adhesive layer and the substrate; and third, introducing photoinitiators to accelerate the UV curing process. Furthermore, to achieve reversibility of the adhesive layer, superabsorbent polymers are added to enhance its hydrolytic capacity. These methods have achieved some success in applications on traditional materials such as glass and metals, demonstrating good adhesion performance.

[0004] However, existing UV hydrolyzable adhesives still have significant shortcomings when applied to novel lightweight composite materials (such as carbon fiber composites and glass fiber reinforced plastics). In particular, they are prone to unstable adhesion on these material surfaces, leading to insufficient bond strength or residues after hydrolysis, severely impacting their practical application. Therefore, effectively solving the adhesion problem of UV hydrolyzable adhesives to surfaces such as carbon fiber composites and glass fiber reinforced plastics, while also maintaining their hydrolytic performance, has become a pressing technical bottleneck that needs to be overcome. Summary of the Invention

[0005] To improve the adhesion stability of UV hydrolysate on lightweight materials such as carbon fiber composites and glass fiber reinforced plastics, and to enable rapid detachment during hydrolysis, this application provides a UV hydrolysate and its preparation method.

[0006] In a first aspect, this application provides a UV hydrolyzable adhesive, which adopts the following technical solution:

[0007] It consists of the following raw materials by weight percentage:

[0008] Modified polyurethane acrylate 40-58%

[0009] Thickening and water-absorbing agent 10-20%

[0010] Photoinitiator 1-3%

[0011] The remainder is reactive diluent;

[0012] The thickening and water-absorbing agent is composed of a polyurethane associative thickener, methanol-etherified melamine-formaldehyde resin, water-absorbing fibers, and hydroxyl acrylate.

[0013] By employing the above technical solutions, modified polyurethane acrylate provides high flexibility and strong adhesion, ensuring that the cured adhesive layer has good mechanical properties and chemical resistance. The polyurethane associative thickener in the tackifying and water-absorbing agent forms a three-dimensional network structure through intermolecular association, significantly improving the thixotropy and anti-sagging properties of the adhesive, while also enhancing the mechanical strength and toughness of the adhesive layer. The methanol-etherified melamine-formaldehyde resin introduces a triazine ring structure, further improving the heat resistance and chemical resistance of the adhesive layer. Its etherification modification reduces hydrolysis sensitivity while retaining moderate water absorption to aid in degumming. The water-absorbing fibers, with their high specific surface area, rapidly absorb moisture and conduct it into the interior of the adhesive layer. After absorbing water, their volume expands, generating mechanical peeling force, promoting the removal of the adhesive layer without leaving residue. The hydroxyl functional groups in the hydroxyl acrylate can form hydrogen bonds with the substrate surface, enhancing initial adhesion and participating in cross-linking reactions during UV curing to form a dense network structure, enhancing the cohesive strength of the adhesive layer, while also promoting water absorption and dispersing the water-absorbing fibers. The synergistic effect of the above components enables the UV hydrolysate adhesive to achieve rapid curing and controllable detachment while maintaining high adhesion strength, making it particularly suitable for temporary bonding scenarios of lightweight materials such as carbon fiber and glass fiber.

[0014] Preferably, the thickening and water-absorbing agent is composed of a polyurethane associative thickener, methanol-etherified melamine-formaldehyde resin, water-absorbing fiber, and hydroxy acrylate in a weight ratio of 1:(1.2-1.5):(3-5):(5-8).

[0015] By employing the above technical solution, the polyurethane associative thickener and methanol-etherified melamine-formaldehyde resin work together to form a stable three-dimensional network structure, significantly improving the mechanical strength and toughness of the adhesive layer and ensuring excellent adhesion performance on lightweight materials such as carbon fiber and glass fiber. The hydroxyl functional groups in the hydroxyl acrylate can form hydrogen bonds with the substrate surface, further enhancing initial adhesion. Simultaneously, they participate in the cross-linking reaction during UV curing, forming a dense network structure and effectively reducing detachment during bonding. The absorbent fibers expand in volume after absorbing water, generating mechanical peeling force. Working synergistically with the modified polyurethane acrylate, they rapidly reduce cohesion during hydrolysis, achieving separation of the adhesive layer from the substrate and preventing residues from remaining on the material surface. Furthermore, the optimized combination of photoinitiator and reactive diluent ensures efficient UV curing, enabling the adhesive layer to achieve ideal curing results in a short time, thus meeting the needs of temporary bonding scenarios.

[0016] Preferably, the absorbent fiber is seaweed fiber and / or sodium acrylate fiber.

[0017] By employing the above-mentioned technical solutions, the introduction of seaweed fiber and sodium acrylate fiber significantly improves the adhesion stability of UV hydrolyzed adhesive on specific substrates, while ensuring its rapid hydrolysis and detachment performance. Seaweed fiber, with its natural biocompatibility and biodegradability, provides excellent water solubility and enhanced mechanical properties, while sodium acrylate fiber, through its superior solubility and flexible molecular structure, further enhances the flexibility and impact resistance of the adhesive. The synergistic effect of the two fibers ensures the adhesion stability of the UV hydrolyzed adhesive on surfaces such as carbon fiber and glass fiber, while enabling rapid detachment without residue during hydrolysis.

[0018] Preferably, the weight ratio of seaweed fiber to sodium acrylate fiber is 3:(1-2).

[0019] By employing the above technical solution, seaweed fiber and sodium acrylate fiber are mixed in a weight ratio of 3:(1-2), which optimizes the water absorption and swelling properties of the UV hydrolyzed adhesive while ensuring good adhesion strength. Seaweed fiber provides high strength and toughness, enhancing the tensile properties and elongation at break of the adhesive, while sodium acrylate fiber, through its solubility and flexible molecular structure, improves the flexibility and impact resistance of the adhesive. The synergistic effect of the two in a specific ratio allows the adhesive to maintain adhesion stability to surfaces such as carbon fiber and glass fiber, while still rapidly detaching during hydrolysis without leaving any residue.

[0020] Preferably, the seaweed fiber and sodium acrylate fiber have a particle size of 1-5 micrometers and a length of 30-50 micrometers.

[0021] By adopting the above technical solution, the particle size of seaweed fiber and sodium acrylate fiber is controlled at 1-5 micrometers, and the length is controlled at 30-50 micrometers, which can significantly improve the performance of UV hydrolysate. Specific effects are as follows:

[0022] Precise control of particle size and length allows for more uniform dispersion of fibers in the colloid, avoiding agglomeration caused by particles that are too large or too small, thereby improving the overall stability and adhesion properties of the colloid.

[0023] Appropriate particle size and length facilitate full contact between the fiber and the substrate surface, increasing the effective adhesion area, and achieving better adhesion stability, especially on carbon fiber materials, glass fiber and other surfaces.

[0024] During hydrolysis, the fiber size design helps to expand rapidly after absorbing water, generating mechanical peeling force to achieve rapid separation between the adhesive layer and the substrate without leaving any residue.

[0025] Preferably, the absorbent fiber is a surface-modified absorbent fiber, and the surface-modified absorbent fiber is composed of the following raw materials by weight percentage:

[0026] γ-Ureapropyltriethoxysilane 1-5%

[0027] Methacrylethyl sulfonate betaine 0.5-3%

[0028] 30-50% water-absorbing fiber

[0029] The remainder is organic solvent.

[0030] By adopting the above technical solution, surface-modified absorbent fibers can significantly improve the overall performance of UV hydrolyzable adhesives. The specific effects are as follows: γ-ureidopropyltriethoxysilane forms a dense coating film with the absorbent fibers, enhancing the fibers' hydrolysis resistance and bonding strength, while also regulating the wettability of the fiber surface and optimizing water absorption performance; methacryloylethyl sulfobetaine forms ionic bonds with the negatively charged groups on the fiber surface through its positively charged groups, further stabilizing the fiber structure and promoting moisture diffusion, thus increasing the water absorption rate; the absorbent fibers, as the main absorbent component, maintain good water absorption and swelling properties after modification, providing mechanical peeling force for the degumming process; the use of organic solvents ensures the uniformity of the modification process and avoids damage to the fiber structure. Overall, this surface-modified absorbent fiber significantly improves the degumming performance after water absorption while enhancing the adhesion strength of the adhesive layer, achieving rapid and residue-free degumming.

[0031] Preferably, the surface-modified absorbent fiber is prepared by the following method:

[0032] Weigh out γ-ureidopropyltriethoxysilane and methacryloylethyl sulfobetaine by weight percentage, dissolve them in an organic solvent, add the absorbent fiber, mix well, filter, and dry the filter residue to obtain surface-modified absorbent fiber.

[0033] By adopting the above technical solution, the preparation method of surface-modified absorbent fibers can significantly improve the overall performance of UV hydrolysate. Specific effects are as follows:

[0034] When γ-ureidopropyltriethoxysilane is combined with absorbent fibers, it forms a dense coating film, which enhances the fiber's resistance to hydrolysis. At the same time, it improves the bonding force between fibers through hydrogen bonding, reducing the residue generated during degumming.

[0035] The introduction of methacryloyl ethyl sulfobetaine imparts positive charge to the fiber, enhances its electrostatic adsorption capacity with negatively charged substrates or fibers, promotes the diffusion of moisture inside the fiber, and increases the water absorption rate.

[0036] This preparation method ensures the uniform distribution of the modifier on the surface of the absorbent fiber, optimizes the wettability and water absorption properties of the fiber, thereby achieving rapid water absorption and swelling, reducing cohesion, and, in conjunction with mechanical peeling, achieving rapid degumming without leaving any residue.

[0037] Preferably, the photoinitiator is photoinitiator TPO and / or photoinitiator 1173.

[0038] By adopting the above technical solutions, the appropriate selection of photoinitiators can efficiently absorb UV light energy and rapidly generate free radicals, thereby significantly improving the curing speed of UV hydrolyzed adhesives. Simultaneously, optimizing the type and concentration of photoinitiators can balance curing speed and curing depth, avoiding internal stress caused by excessively rapid surface curing and ensuring the quality of the adhesive layer.

[0039] Preferably, the reactive diluent is triethylene glycol dimethacrylate and / or bisphenol A diglycidyl ether diacrylate.

[0040] By employing the above technical solution, triethylene glycol dimethacrylate and bisphenol A diglycidyl ether diacrylate, as reactive diluents, can effectively adjust the viscosity of the system while promoting uniform dispersion and mixing of the raw materials. The introduction of these two reactive diluents not only improves the overall fluidity of the adhesive solution but also ensures the stable distribution of the tackifier, water absorbent, modified polyurethane acrylate, and photoinitiator in the system, thereby providing a more uniform reaction environment for the subsequent curing reaction and further optimizing the overall performance of the UV hydrolyzed adhesive.

[0041] Secondly, a method for preparing a UV hydrolyzed gel, obtained by the following method:

[0042] According to the weight parts, the polyurethane associative thickener and methanol etherified melamine-formaldehyde resin were weighed and dissolved in anhydrous ethanol, then hydroxy acrylate was added for one-step activation, then water-absorbing fiber was added and dispersed evenly. The anhydrous ethanol was removed to obtain the thickening and water-absorbing agent.

[0043] Weigh out the modified polyurethane acrylate and photoinitiator and disperse them in 1 / 2 of the reactive diluent to obtain dispersion A; then weigh out the tackifying and water-absorbing agent and disperse it in 1 / 2 of the reactive diluent to obtain dispersion B; then add dispersion B to dispersion A and mix evenly to obtain UV hydrolyzed adhesive.

[0044] By employing the above technical solution, a polyurethane associative thickener and methanol-etherified melamine-formaldehyde resin are dissolved in anhydrous ethanol, and then activated with hydroxyl acrylate, forming a basic structure with high adhesion strength and rapid curing properties. Further addition of absorbent fibers and uniform dispersion significantly enhances the water absorption and degumming properties of the colloid. Stepwise mixing of the thickener with modified polyurethane acrylate, photoinitiator, and reactive diluent ensures thorough dispersion of each component. The resulting UV hydrolyzed adhesive not only exhibits rapid curing and high adhesion strength but also allows for rapid water absorption and desiccation without residue when needed. In particular, this preparation method optimizes the order of component addition and processing, effectively improving the overall performance and stability of the colloid.

[0045] In summary, this application includes at least one of the following beneficial technical effects:

[0046] 1. By specifically selecting polyurethane associative thickener, methanol-etherified melamine-formaldehyde resin, water-absorbing fiber and hydroxyl acrylate as the main components of the thickening and water-absorbing agent, and optimizing their ratio, the adhesion strength and durability of UV hydrolyzed adhesive on the surface of lightweight composite materials such as carbon fiber composites and glass fiber reinforced plastics were significantly improved.

[0047] 2. Specially selected seaweed fiber and sodium acrylate fiber are used as absorbent fibers. Utilizing their unique molecular structure and high water absorption performance, they not only enhance the initial adhesion of the adhesive layer, but also effectively reduce the cohesive strength through rapid water absorption and swelling during hydrolysis, achieving rapid and residue-free detachment.

[0048] 3. By surface modification of the absorbent fibers, using the synergistic effect of γ-ureidopropyltriethoxysilane and methacryloylethyl sulfobetaine, a stable coating film is formed on the fiber surface, further optimizing the wettability and dispersibility of the absorbent fibers, and significantly improving the water absorption rate and degumming performance of the adhesive layer. Attached Figure Description Detailed Implementation

[0049] The present application will be further described in detail below with reference to the embodiments.

[0050] Sources of some raw materials:

[0051] Polyurethane Associative Thickener: German Technical Background, Volker Methanol-etherified melamine-formaldehyde resin: 066LF;

[0052] Modified polyurethane acrylate: R2601 from Jining Tangyi Chemical Co., Ltd.

[0053] Methacrylethyl sulfobetaine: CAS No. 3637-26-1;

[0054] Bisphenol A diglycidyl ether diacrylate (ethoxylated bisphenol A diacrylate) CAS: 4401-02-1.

[0055] Example

[0056] Example 1

[0057] According to the weight proportions, polyurethane associative thickener and methanol-etherified melamine-formaldehyde resin are weighed and dissolved in anhydrous ethanol. Then, hydroxyl acrylate (hydroxyethyl acrylate) is added, stirred evenly, and activated in one step. Then, water-absorbing fibers are added and dispersed evenly. The mixture is heated to 60°C to completely remove the anhydrous ethanol, thus obtaining the thickening and water-absorbing agent. The thickening and water-absorbing agent is composed of polyurethane associative thickener, methanol-etherified melamine-formaldehyde resin, water-absorbing fibers, and hydroxyl acrylate in a weight ratio of 1:1.2:3:5.

[0058] Weigh 40% modified polyurethane acrylate and 3% photoinitiator (photoinitiator TPO) and disperse them in 18.5% reactive diluent to obtain dispersion A; then weigh 20% thickening and water-absorbing agent and disperse them in 18.5% reactive diluent to obtain dispersion B; then add dispersion B to dispersion A and mix evenly to obtain UV hydrolyzed adhesive.

[0059] The absorbent fiber is seaweed fiber. Both the seaweed fiber and sodium acrylate fiber have a particle size of 1-5 micrometers and a length of 30-50 micrometers; in this embodiment, the preferred particle size is 2 micrometers and the length is 38 micrometers. The reactive diluent is composed of triethylene glycol dimethacrylate and bisphenol A diglycidyl ether diacrylate in a weight ratio of 3:1.

[0060] Example 2

[0061] The difference between Example 2 and Example 1 is that the amount of raw materials used is different, as follows: by weight percentage, 50% modified polyurethane acrylate, 13% tackifier and water absorbent, 2% photoinitiator, and 35% reactive diluent.

[0062] Example 3

[0063] The difference between Example 3 and Example 1 is that the amount of raw materials used is different, specifically as follows: 60% modified polyurethane acrylate, 10% tackifier and water absorbent, 1% photoinitiator, and 29% reactive diluent.

[0064] Example 4

[0065] The difference between Example 4 and Example 1 is that the absorbent fiber is sodium acrylate fiber.

[0066] Example 5

[0067] The difference between Example 5 and Example 1 is that the weight ratio of seaweed fiber and sodium acrylate fiber is 3:1.

[0068] Example 6

[0069] The difference between Example 6 and Example 1 is that the weight ratio of seaweed fiber and sodium acrylate fiber is 3:2.

[0070] Example 7

[0071] The difference between Example 7 and Example 5 is that the absorbent fiber is a surface-modified absorbent fiber, which is prepared by the following method:

[0072] Weigh 1% γ-ureidopropyltriethoxysilane and 3% methacryloylethyl sulfobetaine in 66% methanol by weight percentage, then add 30% absorbent fiber, mix evenly, filter, and dry the filter residue to obtain surface-modified absorbent fiber.

[0073] Example 8

[0074] The difference between Example 8 and Example 7 is that the amounts of raw materials are different, as follows: 4.2% γ-ureopropyltriethoxysilane, 0.8% methacryloylethyl sulfobetaine, 40% absorbent fiber, and 55% methanol.

[0075] Example 9

[0076] The difference between Example 9 and Example 7 is that the amounts of raw materials are different, specifically as follows: 5% γ-ureidopropyltriethoxysilane, 0.5% methacryloylethyl sulfobetaine, 50% absorbent fiber, and 49.5% methanol.

[0077] Comparative Example

[0078] Comparative Example 1

[0079] The difference between Comparative Example 1 and Example 1 is that the tackifying and water-absorbing agent was replaced with an equal amount of modified polyurethane acrylate.

[0080] Comparative Example 2

[0081] The difference between Comparative Example 2 and Example 1 is that the absorbent fibers are replaced with an equal amount of hydroxy acrylate.

[0082] Comparative Example 3

[0083] The difference between Comparative Example 3 and Example 1 is that the methanol-etherified melamine-formaldehyde resin is replaced with an equal amount of hydroxy acrylate.

[0084] Performance testing

[0085] Test Methods / Test Methods: Peel Strength: GB / T 2790-1995 "Adhesives 180° Peel Strength Test Method: Flexible Materials vs. Rigid Materials". Specifically, the UV hydrolysate adhesives obtained in Examples 1-9 and Comparative Examples 1-3 are adhered to the surfaces of carbon fiber composite boards and glass fiber reinforced plastic boards, respectively. After curing (irradiated with 365nm wavelength ultraviolet light for 1 min), the peel strength is tested. Hydrolysis Detachment: The UV hydrolysate adhesives obtained in Examples 1-9 and Comparative Examples 1-3 are adhered to the surfaces of carbon fiber composite boards and glass fiber reinforced plastic boards, respectively. After curing (irradiated with 365nm wavelength ultraviolet light for 1 min), a 0.2mm thick UV hydrolysate film is formed on the surface. The film is then immersed in water at 23°C for 10 min, removed, and air-dried. The surface is then observed with a 50x magnifying glass to see if there is any residual UV hydrolysate adhesive. If the above phenomenon occurs, it is considered unqualified.

[0086] The specific experimental data are shown in Table 1.

[0087] Table 1. Experimental data of Examples 1-9 and Comparative Examples 1-3

[0088]

[0089]

[0090] Based on Example 1 and Comparative Examples 1-3 and Table 1, it can be seen that the peel strength of Comparative Examples 1-3 is lower than that of Example 1, and the dehydration separation effect of Example 1 is better. This indicates that the use of a thickening and water-absorbing agent composed of polyurethane associative thickener, methanol etherified melamine-formaldehyde resin, water-absorbing fiber, and hydroxyl acrylate can achieve better stability on the surface of carbon fiber composites and glass fiber reinforced plastics, and is easy to hydrolyze and separate, thus improving its practicality.

[0091] Comparing Examples 1 and 7, it can be seen that the peel strength of Example 1 is lower than that of Example 7, indicating that the surface-modified absorbent fiber of this application can further improve the adhesion performance of UV hydrolyzed adhesive and improve its stability on the surface of carbon fiber composites and glass fiber reinforced plastics.

[0092] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A UV hydrolyzable adhesive, characterized in that, It consists of the following raw materials by weight percentage: Modified polyurethane acrylate 40-58% Thickening and water-absorbing agent 10-20% Photoinitiator 1-3% The remainder is reactive diluent; The thickening and water-absorbing agent is composed of polyurethane associative thickener, methanol-etherified melamine-formaldehyde resin, water-absorbing fiber, and hydroxy acrylate in a weight ratio of 1:(1.2-1.5):(3-5):(5-8); The absorbent fiber is seaweed fiber and / or sodium acrylate fiber; The modified polyurethane acrylate is R2601 from Jining Tangyi Chemical Co., Ltd.

2. The UV hydrolyzable adhesive according to claim 1, characterized in that: The weight ratio of seaweed fiber to sodium acrylate fiber is 3:(1-2).

3. The UV hydrolyzable adhesive according to claim 2, characterized in that: The seaweed fiber and sodium acrylate fiber have a particle size of 1-5 micrometers and a length of 30-50 micrometers.

4. A UV hydrolyzable adhesive according to any one of claims 1-3, characterized in that: The absorbent fiber is a surface-modified absorbent fiber, and the surface-modified absorbent fiber is composed of the following raw materials by weight percentage: γ-Uretopropyltriethoxysilane 1-5% Methacrylethyl sulfonate betaine 0.5-3% 30-50% absorbent fiber The remainder is organic solvent.

5. The UV hydrolyzable adhesive according to claim 4, characterized in that, The surface-modified absorbent fiber is prepared by the following method: Weigh out γ-ureidopropyltriethoxysilane and methacryloylethyl sulfobetaine by weight percentage, dissolve them in an organic solvent, add the absorbent fiber, mix well, filter, and dry the filter residue to obtain surface-modified absorbent fiber.

6. The UV hydrolyzable adhesive according to claim 1, characterized in that: The photoinitiator is photoinitiator TPO and / or photoinitiator 1173.

7. The UV hydrolyzable adhesive according to claim 1, characterized in that: The reactive diluent is triethylene glycol dimethacrylate and / or bisphenol A diglycidyl ether diacrylate.

8. A method for preparing a UV hydrolyzed gel as described in any one of claims 1-7, characterized in that, Obtained by the following method: According to the weight parts, the polyurethane associative thickener and methanol etherified melamine-formaldehyde resin were weighed and dissolved in anhydrous ethanol, then hydroxy acrylate was added for one-step activation, then water-absorbing fiber was added and dispersed evenly. The anhydrous ethanol was removed to obtain the thickening and water-absorbing agent. Weigh out the modified polyurethane acrylate and photoinitiator and disperse them in 1 / 2 of the reactive diluent to obtain dispersion A; then weigh out the tackifying and water-absorbing agent and disperse it in 1 / 2 of the reactive diluent to obtain dispersion B; then add dispersion B to dispersion A and mix evenly to obtain UV hydrolyzed adhesive.

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