CN111072910A - Nonionic polyurethane acrylate and preparation method and application thereof - Google Patents

Abstract

The invention discloses nonionic polyurethane acrylate and a preparation method and application thereof, wherein the nonionic polyurethane acrylate comprises the following raw materials: 1 molar part of polyethylene glycol, 2 molar parts of diisocyanate, 2 molar parts of multifunctional hydroxy acrylate, a proper amount of catalyst and a proper amount of polymerization inhibitor; wherein the polyethylene glycol has a molecular weight greater than 2000. The stable emulsion is formed by utilizing certain water solubility of the polyethylene glycol chain segment and the riveting effect of lipophilic components at two ends on UV resin oil drops, so that better emulsifying property is obtained.

Description

Nonionic polyurethane acrylate and preparation method and application thereof

Technical Field

The invention relates to the technical field of UV (ultraviolet) curing resin, in particular to nonionic polyurethane acrylate and a preparation method and application thereof.

Background

Most of the existing PVD primer coating is composed of polyurethane acrylate, a monomer, an initiator, a solvent and the like, wherein the content of the solvent is over 50 percent, the VOC emission is high, the current increasingly strict environmental protection requirements are not met, and the water-based PVD primer is imperative.

Most of polyurethane acrylate resins which can be used for the water-based PVD primer in the market are emulsion type products, the emulsion type resins do not have the capability of re-emulsifying other conventional oily UV resins, and water-based resin products with excellent emulsified oily UV resins have no related reports at home and abroad, so that the application of the water-based PVD primer is limited.

Disclosure of Invention

The invention aims to at least solve one of the technical problems in the prior art, and in the first aspect, the invention provides the nonionic polyurethane acrylate, wherein polyethylene glycol with a certain molecular weight is used as a hydrophilic chain segment, and a multifunctional acrylate monomer is used as an oleophilic component, so that the better capability of emulsifying the oily UV resin and the UV monomer is ensured.

The nonionic urethane acrylate according to the embodiment of the first aspect of the present invention comprises the following raw materials:

1 molar part of polyethylene glycol, 2 molar parts of diisocyanate, 2 molar parts of multifunctional hydroxy acrylate, a proper amount of catalyst and a proper amount of polymerization inhibitor;

the molecular weight of the polyethylene glycol is more than 2000.

The nonionic polyurethane acrylate provided by the embodiment of the invention has at least the following beneficial effects:

the polyethylene glycol is used for providing hydrophilicity, the multifunctional hydroxyl acrylate is grafted at two ends of the polyethylene glycol through diisocyanate, the multifunctional hydroxyl acrylate contains a plurality of double bonds, can be well combined with UV resin and UV monomer oil drops and is anchored on the surface of oily liquid drops, and stable emulsion is formed by utilizing certain water solubility of a hydrophilic chain segment and the riveting effect of lipophilic components at two ends on the UV resin oil drops, so that better emulsifying performance is obtained. Meanwhile, a plurality of double bonds contained in the molecule can also participate in the UV curing reaction, so that the performance of the coating film is improved.

In a second aspect, there is provided the use of the above non-ionic urethane acrylate in a water-borne PVD primer.

In a third aspect, a method for preparing a nonionic urethane acrylate is provided, which comprises the steps of:

s1, taking 1 molar part of polyethylene glycol, heating for melting, and dehydrating in vacuum;

s2, adding 2 molar parts of diisocyanate in a nitrogen atmosphere, uniformly stirring, adding a catalyst, and reacting until the NCO% approaches the theoretical midpoint;

s3, dropping multifunctional hydroxyl acrylate containing a polymerization inhibitor, wherein the molar ratio of the multifunctional hydroxyl acrylate to the diisocyanate is 1:1, and reacting until the NCO% approaches the theoretical end point.

Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present application more apparent, the following detailed description is further provided in conjunction with specific embodiments. The embodiments described herein are only some of the embodiments of the present application and should not be construed as limiting the scope of the present application.

The nonionic polyurethane acrylate provided by the embodiment of the invention comprises the following raw materials:

1 molar part of polyethylene glycol, 2 molar parts of diisocyanate, 2 molar parts of multifunctional hydroxy acrylate, a proper amount of catalyst and a proper amount of polymerization inhibitor.

The polyethylene glycol is used for providing hydrophilicity, the multifunctional hydroxyl acrylate is grafted at two ends of the polyethylene glycol through diisocyanate, contains a plurality of double bonds, can participate in UV curing reaction, can be well combined with UV resin and UV monomer oil drops, is anchored on the surface of oily liquid drops, and forms stable emulsion by utilizing certain water solubility of a hydrophilic chain segment and the riveting effect of two-end oleophylic components on the UV resin oil drops to obtain better emulsifying performance. The molecular weight of polyethylene glycol has a great influence on the emulsifying performance, and the inventor finds that the molecular weight of polyethylene glycol is preferably more than 2000, more preferably more than 3000, and most preferably 3000-5000 through experiments. The polyethylene glycol has too low molecular weight and poor water solubility; too high a molecular weight can adversely affect the water resistance of the coating, and may be too hydrophilic to be completely water soluble, resulting in poor emulsion stability and easy demulsification.

The type of diisocyanate is not particularly limited, and may be at least one selected from isophoron diisocyanate, hexamethylene diisocyanate, Toluene Diisocyanate (TDI), diphenylmethane diisocyanate (MDI), hydrogenated diphenylmethane diisocyanate, and the like, with aromatic diisocyanates being preferred. The benzene ring has larger polarity and can be well combined with the light-cured resin or the monomer, thereby being beneficial to emulsifying the light-cured resin and the monomer and improving the stability of the emulsion.

The multifunctional hydroxyl acrylate contains a plurality of double bonds, can provide better lipophilicity, and can participate in UV curing reaction to improve the performance of a coating film. The multifunctional hydroxy acrylate may be selected from at least one of pentaerythritol triacrylate (PETA), Dipentaerythritol Pentaacrylate (DPHA), and the like, for example.

The polymerization inhibitor and the catalyst may be selected from those known in the art, for example, dibutyltin laurate, organobismuth catalyst, etc. may be used as the catalyst, and tert-butyl-p-diphenol, p-methoxyphenol, 2, 6, 6-tetramethylpiperidine-1-oxyl (TEMPO), etc. may be used as the polymerization inhibitor. The dosage of the two is respectively and independently 0.02-0.05% of the total weight of the polyethylene glycol, the diisocyanate and the multifunctional hydroxyl acrylate.

The preparation method of the nonionic polyurethane acrylate provided by the embodiment of the invention comprises the following steps:

s1, taking 1 molar part of polyethylene glycol, heating for melting, and dehydrating in vacuum. The vacuum dehydration temperature is preferably 100-120 ℃, and dehydration is preferably carried out until the water content is lower than 0.05%.

S2, adding 2 molar parts of diisocyanate in a nitrogen atmosphere, wherein the process temperature can be 30-60 ℃, stirring uniformly, adding a catalyst, and reacting until the NCO% approaches the theoretical midpoint, wherein the reaction temperature is preferably not lower than 70 ℃.

S3, dripping multifunctional hydroxy acrylate containing a polymerization inhibitor, wherein the mol ratio of the multifunctional hydroxy acrylate to diisocyanate is 1:1, the process can be carried out at the temperature of below 60 ℃, and after dripping is finished, the reaction is preferably carried out at the temperature of not less than 70 ℃ until the NCO% approaches the theoretical endpoint.

In the above steps, all reactions are always carried out under the protection of nitrogen, and the-NCO content can be determined by a di-n-butylamine method. The selection of the individual starting materials and their action in the examples of the process can be made with reference to the examples of nonionic urethane acrylates described above, which are not repeated here.

Due to the excellent emulsifying property, the nonionic urethane acrylate of the product embodiment or the nonionic urethane acrylate prepared by the method embodiment is particularly suitable for being applied to the water-based PVD primer.

The details are given below by way of illustrative example, in which dibutyltin laurate is used as the catalyst, Dabco T-12 is available from the American Airtight chemical industry, p-methoxyphenol is used as the polymerization inhibitor, the amounts of polymerization inhibitor and catalyst are 0.03% of the total weight of polyethylene glycol, diisocyanate and multifunctional hydroxy acrylate, respectively, and the raw materials used are analytically pure.

Example 1

(1) Putting 1mol of polyethylene glycol (molecular weight is 3000) into a four-neck flask with a mechanical stirring device, a reflux device and a dropping funnel, heating to 100-120 ℃, and pumping water in vacuum for 3 hours to reduce the water content to below 0.05%.

(2) And (3) cooling to 40-60 ℃, adding 2mol of MDI and a proper amount of catalyst, slowly heating to 70-80 ℃ under the protection of nitrogen, reacting at constant temperature, and measuring NCO% by a di-n-butylamine method to be close to the theoretical midpoint.

(3) And (3) cooling to below 60 ℃, adding 2mol of PETA dissolved with a polymerization inhibitor into a dropping funnel, slowly dropping the PETA into the reactant in the step (2), taking about 1 hour, slowly heating to 70-80 ℃ after dropping, reacting at a constant temperature, measuring the NCO% by a di-n-butylamine method to be close to a theoretical endpoint (in the embodiment, the NCO% reaches below 0.1%), cooling to 60 ℃, and discharging to obtain the transparent viscous liquid resin.

Example 2

The difference compared to example 1 is that the polyethylene glycol has a molecular weight of 4000.

Example 3

The difference compared to example 1 is that the molecular weight of polyethylene glycol is 5000.

Example 4

The difference compared to example 2 is that PETA was replaced by equimolar DPHA.

Example 5

The difference compared to example 4 is that MDI is replaced by equimolar TDI.

Comparative example 1

The difference compared to example 1 is that the molecular weight of polyethylene glycol is 2000.

Comparative example 2

The difference compared to example 1 is that PETA is replaced by equimolar hydroxyethyl acrylate (HEA).

The properties of the resins prepared in the examples and comparative examples are illustrated below using only one PVD primer as an example.

The PVD primer comprises the following components in parts by weight:

10 parts of UV-3000B resin, 8 parts of urethane acrylate (6145-100, chang), 15 parts of trimethylolpropane triacrylate, 4 parts of 1, 6-hexanediol diacrylate (HDDA), 2 parts of photoinitiator 184, 4 parts of propylene glycol methyl ether, 0.3 part of digao 245, 0.3 part of defoamer 902W, 0.3 part of thickener and 50 parts of water.

The preparation process of the coating comprises the following steps: adding the prepared resin, UV3000B, 6145-100, TM, HDDA, 184 and PM into a reaction kettle, heating to 40 ℃, dispersing for 30min, slowly adding water, taking 1h to obtain emulsion, then adding digao 245, defoaming agent 902W and thickening agent, and dispersing for 30min to obtain the PVD primer.

The coating construction process comprises the following steps:

film thickness: 20 +/-2 microns;

IR temperature: 60 ℃;

IR time: 6 min;

curing energy: 800hj/cm²。

The properties of the coating are shown in table 1:

TABLE 1

From the above results, it can be seen that the resins prepared in examples 1 to 5 have good emulsifying properties, the obtained coating has milky appearance with obvious blue light, the 60 ℃ heat storage of the coating can satisfy more than 14D, and the coating has good paint film appearance, boiling resistance, high temperature and high humidity resistance. As can be seen from comparative example 1, the molecular weight of polyethylene glycol is too low, which has a significant effect on the emulsifying properties. Comparative example 2 using a monofunctional acrylate monomer, the emulsifying ability was poor. Due to poor emulsifying property and poor heat storage stability of the paint, the components of the paint film are not uniformly distributed after being cured, so that a plurality of pits are formed in the appearance of the paint film, and the local water resistance is poor, thereby affecting the overall water resistance of the paint film, such as boiling resistance, high temperature and high humidity and the like.

Claims (10)

1. The nonionic polyurethane acrylate is characterized by comprising the following raw materials:

1 molar part of polyethylene glycol, 2 molar parts of diisocyanate, 2 molar parts of multifunctional hydroxy acrylate, a proper amount of catalyst and a proper amount of polymerization inhibitor;

the molecular weight of the polyethylene glycol is more than 2000.

2. The nonionic urethane acrylate according to claim 1, wherein the molecular weight of the polyethylene glycol is 3000 to 5000.

3. The nonionic urethane acrylate according to claim 1 wherein the diisocyanate is at least one member selected from the group consisting of isophoron diisocyanate, hexamethylene diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, and hydrogenated diphenylmethane diisocyanate.

4. The nonionic urethane acrylate according to claim 1, wherein the multifunctional hydroxy acrylate is selected from pentaerythritol triacrylate and/or dipentaerythritol pentaacrylate.

5. The nonionic urethane acrylate according to claim 1, wherein dibutyltin laurate and/or an organobismuth catalyst is used as the catalyst.

6. The nonionic urethane acrylate according to claim 1 or 5, wherein the amount of the catalyst is 0.02 to 0.05% by weight based on the total weight of the polyethylene glycol, the diisocyanate and the polyfunctional hydroxy acrylate.

7. The nonionic urethane acrylate according to claim 1, wherein the polymerization inhibitor is at least one of t-butyl-p-diphenol, p-methoxyphenol diphenol and 2, 2, 6, 6-tetramethylpiperidine-1-oxyl.

8. The nonionic urethane acrylate according to claim 1 or 7, wherein the amount of the polymerization inhibitor is 0.02 to 0.05% of the total weight of the polyethylene glycol, the diisocyanate and the polyfunctional hydroxy acrylate.

9. Use of the nonionic urethane acrylates of any one of claims 1 to 8 in aqueous PVD primers.

10. A preparation method of nonionic urethane acrylate is characterized by comprising the following steps:

s1, taking 1 molar part of polyethylene glycol, heating for melting, and dehydrating in vacuum;

s2, adding 2 molar parts of diisocyanate in a nitrogen atmosphere, uniformly stirring, adding a catalyst, and reacting until the NCO% approaches the theoretical midpoint;

s3, dropping multifunctional hydroxyl acrylate containing a polymerization inhibitor, wherein the molar ratio of the multifunctional hydroxyl acrylate to the diisocyanate is 1:1, and reacting until the NCO% approaches the theoretical end point.