Ultraviolet multi-crosslinking-site crosslinking agent and preparation method thereof

Abstract

The ultraviolet cross-linking agent is a chemical substance, and a cross-linking reaction of monomers is initiated through ultraviolet radiation to form a cross-linked network. The method is mainly applied to the fields of coatings, printing ink, adhesives, plastics, dielectric elastomers and the like, and is used for improving the mechanical properties of materials. The number of cross-linking points of an existing two-cross-linking-site cross-linking agent is limited, enough high cross-linking density can not be achieved, and therefore the mechanical property is poor. In order to overcome the defect, the invention discloses an ultraviolet multi-crosslinking-site crosslinking agent and a preparation method thereof. The multi-site cross-linking agent has more than three cross-linking sites, so that a more complex cross-linking network can be formed to improve the mechanical property of the material.

Description

Technical Field

[0001] This application relates to the field of photocuring, and relates to an ultraviolet multi-crosslinking site crosslinking agent and a preparation method thereof. Background Art

[0002] An ultraviolet crosslinking agent is a chemical substance that initiates the crosslinking reaction of monomers through ultraviolet radiation to form a crosslinked network. It is mainly applied in fields such as coatings, inks, adhesives, plastics, and dielectric elastomers to improve the mechanical properties of materials. When using existing crosslinking agents with two crosslinking sites, we may encounter the following limitations or challenges: 1. Crosslinking density limitation: Using a crosslinking agent with two crosslinking sites may not be able to achieve a sufficiently high crosslinking density. The number of crosslinking points is limited and may not be able to cover the entire material structure, resulting in an insufficiently tight crosslinked network and affecting the mechanical properties and stability of the material; 2. Mechanical property limitation: A crosslinking agent with two crosslinking sites may not be able to provide enough crosslinking points to increase the strength and hardness of the material. The number of connection points in the crosslinked network is limited and may not be able to effectively disperse stress, resulting in the material being prone to fracture or deformation when stressed. To overcome these limitations, multi-site crosslinking agents have emerged. The multi-site crosslinking agent introduces multiple crosslinking sites and solves the limitations of the two-site crosslinking agent. The advantages of the multi-site crosslinking agent include higher crosslinking density, improved mechanical properties of the material, and stability. The present invention discloses an ultraviolet multi-crosslinking site crosslinking agent and a preparation method thereof. The multi-site crosslinking agent is a product obtained by grafting isocyanate onto polyol. The present invention provides a preparation method for the crosslinking agent, including separately mixing polyol, inhibitor, solvent, isocyanate, and solvent; pouring the two mixed solutions into the same oil bath device and reacting at a certain temperature for a period of time; pouring an appropriate amount of deionized water into the mixed solution; taking out the precipitated product and repeatedly washing it with deionized water; freeze-drying the washed product. The crosslinking agent of the present invention has a low solubility in esters and requires heating to increase solubility, and its usage method is subject to certain limitations. Summary of the Invention

[0003] The present invention provides an ultraviolet multi-crosslinking site crosslinking agent and a preparation method thereof in view of the deficiencies of the existing ultraviolet two-site crosslinking agent. The crosslinking agent of the present invention has the advantages of wide raw material sources, simple preparation process, and multiple crosslinking sites.

[0004] The present invention aims to disclose a preparation method for the above-mentioned various ultraviolet multi-site crosslinking agents. The specific steps of the preparation method are as follows; (1) Separately mix polyol, inhibitor, solvent, isocyanate, and solvent; (2) Pour the two mixed solutions into the same oil bath device and react at a certain temperature for a period of time; (3) Pour an appropriate amount of deionized water into the mixed solution; (4) Take out the precipitated product and wash it repeatedly with deionized water; (5) Lyophilize the washed product to obtain a multi-crosslinking site crosslinking agent.

[0005] In the present invention, preferably, the molar ratio of the polyol, inhibitor, isocyanate, and solvent in step (1) is 10:(0.001 - 1):(10 - 100):(1 - 100).

[0006] In the present invention, preferably, the polyol in step (1) is one or more of glycerol, erythritol, xylitol, sorbitol, mannitol, inositol, maltitol, α-cyclodextrin, β-cyclodextrin, γ-cyclodextrin, and δ-cyclodextrin.

[0007] In the present invention, preferably, the inhibitor in step (1) is one or more of hydroquinone, p-tert-butylcatechol, pyrogallol, 2,6-di-tert-butyl-p-cresol, 4,4'-dihydroxybiphenyl, 4-methoxyphenol, bisphenol A, and wood tar.

[0008] In the present invention, preferably, the isocyanate in step (1) is one or more of allyl isocyanate, 2-isocyanatoethyl acrylate, and isocyanatoethyl methacrylate.

[0009] In the present invention, preferably, the solvent in step (1) is one or more of N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, and acetone.

[0010] In the present invention, preferably, the temperature in step (2) is 20 - 80 °C and the time is 0.5 - 72 h.

[0011] In the ultraviolet multi-crosslinking site crosslinking agent of the present invention, the number of crosslinking sites per unit molecule is greater than or equal to 3, each unit molecule of polyol contains 3 or more hydroxyl groups, each hydroxyl group can react with isocyanate, and each isocyanate contains 1 carbon-carbon double bond to form a crosslinking site.

[0012] Compared with the prior art, the present invention has the advantages of wide raw material sources, simple preparation process, and many crosslinking sites. Description of the Drawings Figure 1 It is a single-axis tensile result diagram. Figure 2 It is a single-axis tensile curve diagram.

Claims

1. An ultraviolet multi-crosslinking site crosslinking agent and its preparation method, characterized in that The preparation method includes: (1) Mix polyol, inhibitor, solvent, isocyanate, and solvent separately; (2) Pour the two mixed solutions into the same oil bath device and react at a certain temperature for a period of time; (3) Pour an appropriate amount of deionized water into the mixed solution; (4) Take out the precipitated product and wash it repeatedly with deionized water; (5) Freeze-dry the washed product to obtain a multi-crosslinking site crosslinking agent.

2. In the preparation method according to claim 1, it is characterized in that, The molar ratio of the polyol, inhibitor, isocyanate, and solvent is 10:(0.001 - 1):10 - 100, 1 - 100.

3. In the preparation method according to claim 1, it is characterized in that, The polyol is one or more of glycerol, erythritol, xylitol, sorbitol, mannitol, inositol, maltitol, α-cyclodextrin, β-cyclodextrin, γ-cyclodextrin, and δ-cyclodextrin.

4. In the preparation method according to claim 1, it is characterized in that, The inhibitor is one or more of hydroquinone, p-tert-butylcatechol, pyrogallol, 2,6-di-tert-butyl-p-cresol, 4,4'-dihydroxybiphenyl, 4-methoxyphenol, bisphenol A, and wood tar.

5. In the preparation method according to claim 1, it is characterized in that The isocyanate is one or more of allyl isocyanate, 2-isocyanatoethyl acrylate, and isocyanatoethyl methacrylate.

6. In the preparation method according to claim 1, it is characterized in that, The solvent is one or more of N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, and acetone.

7. In the preparation method according to claim 1, it is characterized in that, The mass of deionized water / mass of mixed solution ≥ 0.

5.

8. In the preparation method according to any one of claims 1, it is characterized in that, The reaction temperature during the oil bath is 20 - 80°C, and the time is 0.5 - 72 h.

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