CN112300366A

CN112300366A - Solvent-free blocked polyurethane and preparation method and application thereof

Info

Publication number: CN112300366A
Application number: CN202011162987.9A
Authority: CN
Inventors: 彭刚阳; 段晓俊; 朱延安
Original assignee: CARPOLY CHEMICAL GROUP CO LTD
Current assignee: CARPOLY CHEMICAL GROUP CO LTD
Priority date: 2020-10-27
Filing date: 2020-10-27
Publication date: 2021-02-02
Anticipated expiration: 2040-10-27
Also published as: CN112300366B

Abstract

The invention relates to solvent-free blocked polyurethane, which is prepared by the following preparation steps: s1, mixing and stirring 33.0-41.0 parts of reactive diluent, 15.0-21.0 parts of sealant and 0.1-0.2 part of catalyst in parts by mass to form a solution, and heating; s2, diluting or dissolving 29.0-35.0 parts of polyisocyanate by using 10.0-20.0 parts of reactive diluent to form a solution A for later use; s3, when the temperature of the solution of S1 reaches 50-70 ℃ and the sealant is completely dissolved, dropwise adding the solution A, and continuously reacting until the-NCO content is lower than 0.1 wt%. The solvent-free blocked polyurethane which can be deblocked at high temperature is prepared by taking an acrylic ester monomer as an active diluent and reacting polyisocyanate with a blocking agent under the action of a catalyst. The solvent-free blocked polyurethane is applied to a UV paint film, so that the heat transfer printing decorative film can be firmly attached to the UV paint film.

Description

Solvent-free blocked polyurethane and preparation method and application thereof

Technical Field

The invention relates to the field of coatings, in particular to solvent-free blocked polyurethane and a preparation method and application thereof.

Background

UV curing refers to a process of converting a substance from a low molecule to a high molecule under irradiation of ultraviolet light, and is different from ordinary thermal curing, natural curing, crosslinking agent curing, and the like. The curing mechanism is as follows: the light irradiation makes the photoinitiator crack into free radicals or anions and cations, further initiates the monomer containing active groups to carry out polymerization reaction, and the monomer is polymerized into an insoluble and infusible solid coating. Compared with the traditional curing technology, the UV curing technology saves energy, has high curing speed and good coating performance, is suitable for large-scale industrial production, and simultaneously, the UV curing material does not contain or only contains a small amount of Volatile Organic Compounds (VOCs) in the curing process, and is known as 'green technology'. Because the UV coating applying the UV curing technology has the advantages, the UV coating is in the gold development period along with the rising of the labor cost of enterprises, the stricter environmental protection requirement and the upgrade of national industry in recent years.

Thermal transfer printing is a commonly used printing technology, and the technology is divided into two parts, namely transfer printing and transfer printing processing. The transfer printing film adopts dot printing (the resolution ratio reaches 300dpi), patterns are printed on the surface of the film in advance, the printed patterns are rich in layers, bright in color, changeable, small in color difference and good in reproducibility, can achieve the effect required by a pattern designer, and is suitable for mass production. The transfer printing processing transfers the exquisite pattern on the transfer printing film on the surface of the product through one-step processing (heating and pressurizing) of a thermal transfer printing machine, and the formed ink layer and the surface of the product are dissolved into a whole, so that the product is vivid and beautiful, and the grade of the product is greatly improved. With the recent upgrading of consumption, the demand of printing patterns on the surfaces of furniture or toys is greater and greater, and compared with the conventional printing technology, the thermal transfer printing has the characteristics of simple printing and high construction efficiency, and is suitable for industrial production line production.

The UV curing technology and the thermal transfer printing technology are both suitable for flow line production, and if the UV curing technology and the thermal transfer printing technology can be combined, thermal transfer printing construction can be immediately carried out on the surface of a cured UV paint film, so that the production efficiency can be greatly improved. However, the problem that the adhesion of the thermal transfer printing pattern film on the un-polished UV paint film is poor due to the high crosslinking density of the paint film after the UV paint is cured greatly limits the popularization and application of the UV curing technology combined with the thermal transfer printing technology in the field of furniture and toy manufacturing.

Therefore, there is a need to find a new type of heat transferable UV paint that overcomes the above-mentioned drawbacks of the prior art.

Disclosure of Invention

In order to overcome the defects, the invention aims to provide solvent-free blocked polyurethane and a heat-transferable UV paint containing the solvent-free blocked polyurethane.

The solvent-free blocked polyurethane which can be deblocked at high temperature is prepared by taking an acrylic ester monomer as an active diluent and reacting polyisocyanate with a blocking agent under the action of a catalyst.

The invention takes acrylate monomer as reactive diluent when preparing the blocked polyurethane. The acrylate monomer contains double bonds and can participate in the reaction during ultraviolet light curing, and the addition of 100# solvent oil, propylene glycol methyl ether acetate or ethyl acetate and other inert diluents for reducing the viscosity of the closed polyurethane is avoided. The addition of the inert diluent into the UV-curable resin is not environment-friendly and can influence the proceeding of the UV-curable free radical polymerization reaction, so that the problems of no drying of a paint film, whitening of the paint film or abnormal adhesion and the like are easily caused. The solvent-free blocked polyurethane is applied to a UV (ultraviolet) paint film, so that the blocked polyurethane contained in the paint film can be deblocked under the condition of about 200 ℃ in the thermal transfer printing process, and the deblocked NCO groups are used as a cross-linking agent to react with hydroxyl in the UV paint film and hydroxyl in a thermal transfer printing film hot melt adhesive, so that the thermal transfer printing film is firmly attached to the UV paint film. The invention selects isocyanate tripolymer or biuret when preparing the blocked polyurethane, avoids the problem that the conventional blocked polyurethane prepared by adopting isocyanate monomer can release isocyanate monomer with higher toxicity after deblocking, therefore, the invention can be suitable for the environment needing manual operation. The deblocking temperature of the solvent-free blocked polyurethane is about 160 ℃ preferably, which is far higher than the highest temperature of the UV paint in the transportation and storage processes, so that the stability of the UV paint containing the blocked polyurethane in the transportation and storage processes is ensured. Meanwhile, the temperature of the UV paint film during curing can not reach the deblocking temperature of the blocked polyurethane, and the thermal transfer printing temperature of about 200 ℃ is higher than the deblocking temperature of about 160 ℃ of the blocked polyurethane by about 40 ℃, so that the blocked polyurethane can be deblocked only rapidly in the thermal transfer printing process and reacts with hydroxyl in the thermal transfer printing film rapidly after deblocking.

The invention aims to provide solvent-free blocked polyurethane, which is realized by the following technical scheme:

the solvent-free blocked polyurethane is prepared by the following preparation steps: s1, mixing, stirring and heating 33.0-41.0 parts of reactive diluent, 15.0-21.0 parts of sealant and 0.1-0.2 part of catalyst in parts by mass; s2, diluting or dissolving 29.0-35.0 parts of polyisocyanate by using 10.0-20.0 parts of reactive diluent to form a solution A for later use; s3, when the temperature of the solution of S1 reaches 50-70 ℃ and the sealant is completely dissolved, dropwise adding the solution A, and continuously reacting until the-NCO content is lower than 0.1 wt%;

wherein the reactive diluent is an acrylate monomer with two functional groups;

the blocking agent is ketoxime monomer;

the solid content of the polyisocyanate was 100% by weight.

Further, the catalyst is selected from organic bismuth or organic tin.

Further, the polyisocyanate is selected from HDI trimer, HDI biuret or IPDI trimer.

Further, the ketoxime monomer is selected from one of methyl ethyl ketoxime, dimethyl ketoxime, acetophenone ketoxime, methyl isobutyl ketoxime, cyclopentanone oxime and cyclohexanone oxime.

Another object of the present invention is to provide a heat-transferable UV paint including the above solvent-free blocked polyurethane.

Further, the preparation raw materials of the UV paint capable of being thermally transferred comprise the following components in parts by mass:

further, the number of functional groups of the urethane acrylate oligomer is less than or equal to 6.

Further, the epoxy acrylate oligomer is a difunctional epoxy acrylate oligomer;

further, the polyester acrylate oligomer is a difunctional, trifunctional, or tetrafunctional polyester acrylate oligomer.

Further, the active monomer is an acrylate monomer containing double bonds.

The invention has the following beneficial effects:

1) the solvent-free blocked polyurethane which can be deblocked at high temperature is prepared by taking an acrylate monomer as an active diluent and reacting polyisocyanate with a blocking agent under the action of a catalyst. The blocked polyurethane contained in the cured UV paint film can be deblocked under the condition of about 200 ℃ in the thermal transfer process, and the solvent-free blocked polyurethane is applied to the UV paint film, so that the blocked polyurethane contained in the paint film can be deblocked under the condition of about 200 ℃ in the thermal transfer process, and the deblocked-NCO group is used as a cross-linking agent to react with hydroxyl in the UV paint film and hydroxyl in a thermal transfer printing pattern film hot melt adhesive, thereby realizing the firm adhesion of the thermal transfer printing pattern film on the UV paint film.

2) The invention takes acrylic ester monomer as reactive diluent when preparing the blocked polyurethane. The acrylate monomer contains double bonds and can participate in the reaction during ultraviolet curing, so that the problem of adding inert diluents such as ethyl acetate and the like for reducing the viscosity of the closed polyurethane is solved. The addition of the inert diluent into the UV-curable resin is not environment-friendly and can influence the proceeding of the UV-curable free radical polymerization reaction, so that the problems of no drying of a paint film, whitening of the paint film or abnormal adhesion and the like are easily caused.

3) The ketoxime monomer is selected when the blocked polyurethane is prepared, so that the problem that the conventional blocked polyurethane prepared from the isocyanate monomer releases the isocyanate monomer with high toxicity after deblocking is solved, and the blocked polyurethane can be suitable for the environment needing manual operation.

4) The solvent-free blocked polyurethane prepared by the invention has an ideal deblocking temperature (about 160 ℃), on one hand, the temperature is far higher than the highest temperature of the common UV paint in the transportation and storage processes, and the stability of the UV paint containing the blocked polyurethane in the transportation and storage processes is ensured; on the other hand, the temperature of the UV paint film during curing is not higher than the deblocking temperature of the blocked polyurethane, and the thermal transfer temperature of about 200 ℃ is higher than the deblocking temperature of about 160 ℃ of the blocked polyurethane by about 40 ℃, so that the blocked polyurethane is only rapidly deblocked during the thermal transfer process, and the deblocked polyurethane rapidly reacts with hydroxyl groups in the thermal transfer printing film.

Detailed Description

In order that the invention may be better understood, reference will now be made to the following examples. The scope of the invention is not limited to the embodiments of the invention. Unless otherwise noted, the ingredients and test methods mentioned in the examples of this patent disclosure are conventional methods known to those skilled in the art.

The bifunctional acrylate monomer related in the embodiment of the invention is purchased from bifunctional acrylate monomers of Sanmu company, with the types of SM623, SM624 and SM627, or purchased from bifunctional acrylate monomers of Changxing company, with the types of EM221, EM2211 and EM 226;

the polyisocyanates involved are HDI trimer HT-100 purchased from Vanhua chemistry, HDI trimer TLA-100 purchased from Asahi formation, HDI biuret HB-100 purchased from Vanhua chemistry or IPDI trimer T1890/100 purchased from Degussa, the solid contents of the polyisocyanates being 100 wt%;

the related urethane acrylate oligomer is purchased from Changxing company, and the types are six-functional 6145-100, six-functional 6150-100, six-functional 6161-100, four-functional 6170-100, four-functional DR-U198 or two-functional DR-U381;

the epoxy acrylate oligomer referred to was purchased from Changxing corporation as difunctional 621A-80, difunctional 623A-80, or difunctional 6215-100; or from American origin, type difunctional PE240, difunctional EA2235 or difunctional EA 2280;

the related active monomer is an acrylate monomer containing double bonds, purchased from Sanmu corporation, and has the model of HEMA, SM623 or SM 631; or from Changxing corporation under the type EM70, EM221 or EM 235.

The free radical initiators involved are purchased from basf under the type Irgacure 184, Darocur 1173, Irgacure TPO-L, Irgacure 819 or Darocur BP.

The related talcum powder is purchased from saint monkey company, and the model is 400 meshes, 600 meshes, 800 meshes, 1000 meshes, 1250 meshes or 3000 meshes;

the defoaming agent, the leveling agent and the wetting dispersant are purchased from Bike company of Germany or Texas company of winning and are common products of the companies.

The determination of the-NCO content of the examples and comparative examples referred to is carried out by:

di-n-butylamine titration method. Weighing about 0.5-1g of isocyanate sample, accurately measuring to 0.0002g, putting into a 250mL conical flask with a plug, not adhering to the bottle neck, adding 5mL of anhydrous acetone, covering the bottle plug, shaking to completely dissolve the sample, or heating on a heating plate to accelerate dissolution. And (3) sucking 20mL of di-n-butylamine anhydrous toluene solution into a conical flask by using a pipette, covering the conical flask with a bottle plug, continuously shaking for 15min, then adding 100mL of isopropanol, dropwise adding 2-3 drops of bromophenol blue indicator, and titrating by using a hydrochloric acid standard titration solution until the solution turns yellow from blue. A blank test (i.e., without consolidating agent sample, the remainder of the test) was performed simultaneously as described above.

The isocyanate group content is expressed in mass percent and is calculated by the following formula:

-NCO％＝(V₁-V₂)×c×0.0420×100/m

in the formula: v₁-volume of hydrochloric acid standard titration solution consumed by the blank, mL;

V₂-volume of hydrochloric acid standard titration solution consumed by the sample, mL;

c, actual concentration of hydrochloric acid standard titration solution, mol/L;

m-mass of sample, g;

0.0420-mass of isocyanate group expressed in g corresponding to 1.00mL of hydrochloric acid standard titration solution [ c (hcl) ═ 1.000mol/L ].

The deblocking temperatures of the examples and comparative examples concerned were determined by: adding a plurality of drops of aniline into solvent-free blocked polyurethane, heating, and obtaining the deblocking temperature of the blocked polyurethane when the blocked polyurethane is turbid.

Example 1

A solvent-free blocked polyurethane 1 is prepared by the following steps:

s1, mixing 33.9 parts by mass of an active diluent SM623, 16.0 parts by mass of methyl ethyl ketoxime and 0.1 part by mass of a catalyst Kat 24 in a four-neck flask, and heating, stirring and dissolving at 50 ℃ to form a solution;

s2, diluting or dissolving 15.0 parts of an active diluent SM623 to form 35.0 parts of polyisocyanate HT-100 to form a solution A for later use;

s3, when the temperature of the solution of the S1 reaches 50 ℃ and the methyl ethyl ketone oxime is completely dissolved, dropwise adding the solution A into the solution of the S1 by using a constant-pressure dropping funnel, completing dropwise adding within 40min, and allowing the solution to continue to react for 75min until the-NCO content is lower than 0.1 wt% in a titration test.

S4, cooling, filtering and discharging to obtain the solvent-free blocked polyurethane, wherein the deblocking temperature is 150 ℃, and the viscosity of the product is 1350cp at 25 ℃ by using a Brookfield rotational viscometer.

The UV paint 1 capable of being thermally transferred is prepared from the following raw materials in parts by weight:

the preparation method of the UV paint 1 capable of thermal transfer printing comprises the following steps: the components are put into a reaction kettle according to the mass portion, stirred for 30min at 1300-1700rpm to prepare a finished product, and the viscosity of the product is 4500cp by using a Brookfield rotary viscometer at 25 ℃.

Example 2

A solvent-free blocked polyurethane 2 is prepared by the following steps:

s1, mixing 37.7 parts by mass of an active diluent SM624, 15.2 parts by mass of dimethyl ketoxime and 0.1 part by mass of a catalyst Kat 320 in a four-neck flask, and heating, stirring and dissolving at 60 ℃ to form a solution;

s2, diluting or dissolving 10.0 parts of reactive diluent SM624 into 37.0 parts of polyisocyanate TLA-100 to form a solution A for later use;

s3, when the temperature of the solution of S1 reaches 70 ℃ and the dimethyl ketoxime is completely dissolved, dropwise adding the solution A into the solution of S1 by using a constant-pressure dropping funnel, completing dropwise adding within 30min, and allowing the solution to continue to react for 100min until the-NCO content is lower than 0.1 wt% in a titration test.

S4, cooling, filtering and discharging to obtain the solvent-free blocked polyurethane, wherein the deblocking temperature is 160 ℃, and the viscosity of the product is 1550cp at 25 ℃ by using a Brookfield rotational viscometer.

The UV paint 2 capable of being thermally transferred is prepared from the following raw materials in parts by weight:

the preparation method of the UV paint 2 capable of being thermally transferred comprises the following steps: the components are put into a reaction kettle according to the mass portion, stirred for 30min at 1300-1700rpm to prepare a finished product, and the viscosity of the product is 6000cp at 25 ℃ by using a Brookfield rotary viscometer.

Example 3

A solvent-free blocked polyurethane 3 is prepared by the following steps:

s1, mixing 35.2 parts by mass of bifunctional acrylate monomer SM627, 20.6 parts by mass of acetophenone oxime and 0.2 part by mass of catalyst DBTL in a four-neck flask, and heating, stirring and dissolving at 70 ℃ to form a solution;

s2, diluting or dissolving 15.0 parts of reactive diluent SM627 by 29.0 parts of polyisocyanate HB-100 to form a solution A for later use;

s3, when the temperature of the solution of S1 reaches 60 ℃ and the acetophenone oxime is completely dissolved, dropwise adding the solution A into the solution of S1 by using a constant-pressure dropping funnel, completing dropwise adding within 20min, and allowing the solution to continue to react for 150min until the-NCO content is lower than 0.1 wt% in a titration test.

S4, cooling, filtering and discharging to obtain the solvent-free blocked polyurethane, wherein the deblocking temperature is 170 ℃, and the viscosity of the product is 2350cp by using a Brookfield rotational viscometer at 25 ℃.

The UV paint 3 capable of being thermally transferred is prepared from the following raw materials in parts by weight:

the preparation method of the UV paint 3 capable of thermal transfer printing comprises the following steps: the components are put into a reaction kettle according to the mass portion, stirred for 30min at 1300-1700rpm to prepare a finished product, and the viscosity of the product is 4500cp by using a Brookfield rotary viscometer at 25 ℃.

Example 4

A solvent-free blocked polyurethane 4 is prepared by the following steps:

s1, mixing 29.7 parts by mass of active diluent EM221, 17.2 parts by mass of methyl isobutyl ketoxime and 0.2 part by mass of catalyst Kat 24 in a four-neck flask, and heating, stirring and dissolving at 55 ℃ to form a solution;

s2, diluting or dissolving 20.0 parts of reactive diluent EM221 to form a solution A by 33.0 parts of polyisocyanate T1890/100 for later use;

s3, when the temperature of the solution of S1 reaches 65 ℃ and the methyl isobutyl ketoxime is completely dissolved, dropwise adding the solution A into the solution of S1 by using a constant-pressure dropping funnel, completing dropwise adding within 40min, and allowing the solution to continue to react for 100min until the-NCO content is lower than 0.1 wt% in a titration test.

S4, cooling, filtering and discharging to obtain the solvent-free blocked polyurethane, wherein the deblocking temperature is 165 ℃, and the viscosity of the product is 1850cp by using a Brookfield rotational viscometer at 25 ℃.

The UV paint 4 capable of being thermally transferred is prepared from the following raw materials in parts by weight:

the preparation method of the UV paint 4 capable of thermal transfer printing comprises the following steps: the components are put into a reaction kettle according to the mass portion, stirred for 30min at 1300-1700rpm to prepare a finished product, and the viscosity of the product is measured to 7000cp at 25 ℃ by using a Brookfield rotary viscometer.

Example 5

A solvent-free blocked polyurethane 5 is prepared by the following steps:

s1, mixing 34.7 parts by mass of active diluent EM2211, 17.2 parts by mass of cyclopentanone oxime and 0.1 part by mass of catalyst Kat 320 in a four-neck flask, and heating, stirring and dissolving at 65 ℃ to form a solution;

s2, diluting or dissolving 15.0 parts of reactive diluent EM2211 to form a solution A for later use, wherein 33.0 parts of polyisocyanate HT-100 is dissolved in the solution A;

s3, when the temperature of the solution of S1 reaches 60 ℃ and the cyclopentanone oxime is completely dissolved, dropwise adding the solution A into the solution of S1 by using a constant-pressure dropping funnel, and completing dropwise adding within 30min, so that the solution continues to react for 125min until the-NCO content is lower than 0.1 wt% in a titration test.

S4, cooling, filtering and discharging to obtain the solvent-free blocked polyurethane, wherein the deblocking temperature is 160 ℃, and the viscosity of the product is 1350cp at 25 ℃ by using a Brookfield rotational viscometer.

The UV paint 5 capable of being thermally transferred is prepared from the following raw materials in parts by weight:

the preparation method of the UV paint 5 capable of thermal transfer printing comprises the following steps: the components are put into a reaction kettle according to the mass portion, and stirred for 20min at 1300-1700rpm to prepare a finished product, and the viscosity of the product is 4500cp by using a Brookfield rotary viscometer at 25 ℃.

Example 6

A solvent-free blocked polyurethane 6 is prepared by the following steps:

s1, mixing 40.8 parts by mass of active diluent EM226, 19 parts by mass of cyclohexanone oxime and 0.1 part by mass of catalyst DBTL in a four-neck flask, and heating, stirring and dissolving at 70 ℃ to form a solution;

s2, diluting or dissolving 10.0 parts of reactive diluent EM226 to form a solution A for later use, wherein 30.0 parts of polyisocyanate TLA 100 is used;

s3, when the temperature of the solution of S1 reaches 50 ℃ and cyclohexanone oxime is completely dissolved, dropwise adding the solution A into the solution of S1 by using a constant-pressure dropping funnel, completing dropwise adding within 20min, and allowing the solution to continue to react for 150min until the-NCO content is lower than 0.1 wt% in a titration test.

S4, cooling, filtering and discharging to obtain the solvent-free blocked polyurethane, wherein the deblocking temperature is 160 ℃, and the viscosity of the product is 2550cp at 25 ℃ by using a Brookfield rotational viscometer.

The UV paint 6 capable of being thermally transferred is prepared from the following raw materials in parts by weight:

Comparative examples section

Comparative example 1A is different from UV paint 1 for a printable thermal transfer printing film prepared in example 1 in that the solvent-free blocked polyurethane 1 prepared in example 1 is not added to comparative example 1A, and other components, parts by mass and preparation methods are the same.

Comparative example 1B differs from the overprintable thermal transfer decal UV lacquer 1 prepared in example 1 in that comparative example 1B replaces the solvent-free blocked polyurethane 1 in the overprintable thermal transfer decal UV lacquer 1 prepared in example 1 with a conventional solvent-containing blocked polyurethane (bayer Desmodur BL 3575/1, germany, deblocking temperature 160 ℃) in equal amounts, and the other ingredients, parts by mass and methods of preparation are the same.

Comparative example 2A is different from UV paint 1 which is prepared in example 2 and can be printed with a heat transfer printing film, in that the solvent-free blocked polyurethane 2 prepared in example 2 is not added in the comparative example 2A, and other components, parts by mass and preparation methods are the same.

Comparative example 2B differs from the printable heat transfer decal UV lacquer 2 prepared in example 2 in that comparative example 2B replaces the solvent-free blocked polyurethane 2 in the printable heat transfer decal UV lacquer 2 prepared in example 2 with a conventional solvent-containing blocked polyurethane (bayer Desmodur BL 3575/1, germany, deblocking temperature 160 ℃) in equal amounts, and the other ingredients, parts by mass and method of preparation are the same.

The difference between the comparative example 3A and the UV paint 3 which is prepared in the example 3 and can be printed with the thermal transfer printing decorative film is that the solvent-free blocked polyurethane 3 prepared in the example 3 is not added in the comparative example 3A, and other components, parts by mass and preparation methods are the same.

Comparative example 3B differs from the overprintable thermal transfer decal UV lacquer 3 prepared in example 3 in that comparative example 3B replaces the solvent-free blocked polyurethane 3 in the overprintable thermal transfer decal UV lacquer 3 prepared in example 3 with a conventional solvent-containing blocked polyurethane (bayer Desmodur BL 3575/1, germany, deblocking temperature 160 ℃) in equal amounts, and the other ingredients, parts by mass and methods of preparation are the same.

Comparative example 4A is different from UV paint 4 which is prepared in example 4 and can be printed with a thermal transfer printing film in that the solvent-free blocked polyurethane 4 prepared in example 4 is not added in comparative example 4A, and other components, parts by mass and preparation methods are the same.

Comparative example 4B differs from example 4 in that comparative example 4B replaces the solvent-free blocked polyurethane 4 of the printable thermally transferable film UV lacquer 4 prepared in example 4 with an equivalent amount of conventional solvent-containing blocked polyurethane (bayer Desmodur BL 3575/1, germany, deblocking temperature 160 c), and the other ingredients, parts by mass and preparation are the same.

Comparative example 5A is different from UV paint 5 prepared in example 5 in that the solvent-free blocked polyurethane 5 prepared in example 5 is not added to comparative example 5A, and the other components, parts by mass and preparation method are the same.

Comparative example 5B differs from the printable heat transfer decal UV lacquer 5 prepared in example 5 in that comparative example 5B replaces the solvent-free blocked polyurethane 5 in the printable heat transfer decal UV lacquer 5 prepared in example 5 with a conventional solvent-containing blocked polyurethane (bayer Desmodur BL 3575/1, germany, deblocking temperature 160 ℃) in equal amounts, and the other ingredients, parts by mass and method of preparation are the same.

Comparative example 6A is different from the UV paint 6 for printing the thermal transfer printing film prepared in example 6 in that the solvent-free blocked polyurethane 6 prepared in example 6 is not added to comparative example 6A, and other components, parts by mass and preparation methods are the same.

Comparative example 6B differs from the overprintable thermal transfer decal UV lacquer 6 prepared in example 6 in that comparative example 6B replaces the solvent-free blocked polyurethane 6 in the overprintable thermal transfer decal UV lacquer 6 prepared in example 6 with a conventional solvent-containing blocked polyurethane (bayer Desmodur BL 3575/1, germany, deblocking temperature 160 ℃) in equal amounts, and the other ingredients, parts by mass and methods of preparation are the same.

Selecting birch veneer as base material at 0.04m²The adhesion of the UV finishes of examples 1 to 6 and comparative examples 1 to 6 was tested after two UV finishes were applied by roll coating (length 0.2m, width 0.2m, thickness 0.005m) to a substrate (a heat transfer film for finish exclusive use by Dongguan color Co.). The adhesion of the heat transfer printed film was tested by the GB9286 crosshatch method (the grade of the crosshatch method adhesion test indicates that the cut edge is completely smooth in grade 0, no peeling occurs at the grid edge, grade 1 indicates that small pieces are peeled off at the intersection of the cut, the actual breakage in the crosshatch area is not more than 5%, grade 2 indicates that the cut edge and/or the intersection is peeled off in an area of more than 5% but less than 15%, grade 3 indicates that a part or the whole of the cut edge is peeled off and/or a part of the cut edge is peeled off in a whole piece, the peeled area exceeds 15% but less than 35%, grade 4 indicates that the cut edge is peeled off in a large piece and/or some of the squares are peeled off in a part or the whole, the area is more than 35% but not more than 65% of the crosshatch area, and grade 5 indicates that the degree of peeling cannot be measured by the standard of grade 4).

TABLE 1 test results of basic Properties of UV paints and adhesion of thermal transfer printing films on painted surfaces thereof in examples 1 to 6, comparative examples 1A to 6A, and comparative examples 1B to 6B

The comparative data above fully illustrate the advancement of the inventive solution over the comparative examples.

The above description of the embodiments is only intended to facilitate the understanding of the method of the invention and its core idea. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle of the present invention, and those improvements and modifications also fall within the scope of the claims of the present invention.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. The solvent-free blocked polyurethane is characterized by being prepared by the following preparation steps: s1, mixing and stirring 33.0-41.0 parts of reactive diluent, 15.0-21.0 parts of sealant and 0.1-0.2 part of catalyst in parts by mass to form a solution, and heating; s2, diluting or dissolving 29.0-35.0 parts of polyisocyanate by using 10.0-20.0 parts of reactive diluent to form a solution A for later use; s3, when the temperature of the solution of S1 reaches 50-70 ℃ and the sealant is completely dissolved, dropwise adding the solution A, and continuously reacting until the-NCO content is lower than 0.1 wt%;

wherein the reactive diluent is an acrylate monomer with two functional groups;

the blocking agent is ketoxime monomer;

the solid content of the polyisocyanate was 100% by weight.

2. The solvent-free blocked polyurethane of claim 1 wherein the catalyst is selected from the group consisting of organobismuth and organotin.

3. Solvent-free blocked polyurethane according to claim 1, characterized in that the polyisocyanate is selected from HDI trimers, HDI biurets or IPDI trimers.

4. The solvent-free blocked polyurethane of claim 1, wherein the ketoxime monomer is selected from the group consisting of methyl ethyl ketoxime, dimethyl ketoxime, acetophenone oxime, methyl isobutyl ketoxime, cyclopentanone oxime, and cyclohexanone oxime.

5. A heat-transferable UV lacquer, characterized in that the solvent-free blocked polyurethane according to any one of claims 1 to 4 is contained in the heat-transferable UV lacquer.

6. The heat-transferable UV paint according to claim 5, wherein the preparation raw materials of the heat-transferable UV paint comprise the following components in parts by mass:

7. the UV heat-transferable paint of claim 6, wherein the urethane acrylate oligomer has a functional group number of 6 or less.

8. The thermally transferable UV paint of claim 6, wherein the epoxy acrylate oligomer is a difunctional epoxy acrylate oligomer;

the polyester acrylate oligomer is a difunctional, trifunctional or tetrafunctional polyester acrylate oligomer.

9. The UV paint capable of being thermally transferred according to claim 6, wherein the reactive monomer is an acrylate monomer containing a double bond.