Polyurethane binder for matte oil and preparation method thereof

Abstract

The invention provides a polyurethane binder for matte oil and a preparation method of the polyurethane binder, and belongs to the technical field of intaglio printing. Alcohol ester soluble polyurethane resin is used as a matrix component, and ethyl acetate, n-propyl acetate and isopropanol are used as solvent components. The polyurethane binder disclosed by the invention is mainly applied to polyurethane printing ink for matte oil, has the characteristics of high matte degree, good heat resistance, scratch resistance and the like, and is excellent in product performance. Due to the fact that the matt oil contains more filler and is a high-solid-content ink system, although the connecting material is of a solvent type, the applied ink is high in solid content and few in added solvent, and compared with traditional alcohol ester soluble type polyurethane ink, the matt oil is more environmentally friendly and economical.

Description

Technical Field

[0001] The invention relates to the technical field of gravure printing, in particular to a polyurethane connecting material for matte oil and a preparation method thereof. Background Art

[0002] At present, the domestic matte oil ink mainly contains composite inks composed of pigments, dispersants, chlorovinyl resins, polyurethane ink binders, n-propyl acetate, ethyl acetate, isopropanol and other solvents, and the printing substrates are mainly film materials such as PET and BOPP. Among them, the polyurethane ink binder is mainly composed of polyurethane resin, ester solvents and alcohol solvents. Polyurethane resin is generated by polymerization reaction of isocyanate, polyester or polyether polyol and small molecule chain extender. In addition to the carbamate group, the macromolecular chain often contains ether bond, ester bond, urea bond and other groups. It is easy to generate hydrogen bonds between these groups, and because of its excellent adhesion to the substrate, wear resistance, scratch resistance and other properties, as well as its soft and hard adjustable advantages, it has been more and more widely used.

[0003] At present, due to the poor dispersion effect of conventional polyurethane system matte oil, matte powder and other matte effect fillers in the system are difficult to be evenly distributed in the polyurethane resin, resulting in a decrease in the matte degree of the matte oil. This is because these matte additives agglomerate and fail to achieve the effect of diffuse reflection. At the same time, due to the agglomeration of fillers in the matte oil resin, the additives in the matte oil system will migrate to the surface. This causes the surface of the matte oil to be prone to cracking, and a light scratch with a fingernail will leave a mark, thus affecting the appearance. Finally, since matte oil is often applied on the outermost layer of printing. In order to meet the heat sealing requirements of packaging bags, the improvement of its heat resistance is also a necessary requirement for responding to the market. Therefore, it is necessary to develop a polyurethane ink binder for matte oil with high matte degree, finger scratch resistance and good temperature resistance. Summary of the invention

[0004] The purpose of the present invention is to provide a polyurethane binder for matte oil, so as to solve the problems of low matte degree, poor heat resistance and poor resistance to finger scratching when the gravure printing ink binder is applied to the matte oil ink system in the prior art.

[0005] The technical solution adopted by the present invention to solve its technical problem is:

[0006] A polyurethane binder for matte oil, wherein the viscosity of the polyurethane binder at 25° C. is 900-1200 mPa□s;

[0007] The preparation raw materials include raw materials for preparing alcohol-ester soluble polyurethane resin and organic solvent;

[0008] The total amount of raw materials for preparing the polyurethane connecting material includes:

[0009]

[0010] Furthermore, the raw materials for preparing the alcohol-ester soluble polyurethane resin include the following components in parts by weight:

[0011]

[0012] Furthermore, the polyester polyol is one or more of neopentyl glycol, ethylene isophthalate, butylene terephthalate, propylene glycol polyol, polyadipate-2-methyl-1,3-propylene glycol polyol, and the average molecular weight of the polyol is 3500-5000.

[0013] Furthermore, the diisocyanate includes a mixture of one or more of isophorone diisocyanate, toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, and hexamethylene diisocyanate.

[0014] Furthermore, the branched chain extender includes one of pentaerythritol, glycerol and trimethylolpropane.

[0015] Furthermore, the catalyst includes one of dibutyltin dilaurate, tetraisobutyl titanate, and triethylamine.

[0016] Furthermore, the amine chain extender includes a mixture of one or more of hydroxyethylethylenediamine, 2-methylpentanediamine, 1,3-cyclohexanedimethylamine, and isophoronediamine.

[0017] Furthermore, the end-capping agent includes one or a mixture of monoethanolamine, tert-butylamine, benzylamine, and octadecylamine.

[0018] A method for preparing a polyurethane binder for matte oil, which is used to prepare the above-mentioned polyurethane binder for matte oil, adopts a prepolymerization and chain extension method:

[0019] (a) Prepolymerization: Add the polyol raw material according to the selected ratio into the main reaction kettle and heat it to 80° C., continue to add the isocyanate raw material in the selected ratio and stir and mix, then heat to 95-130° C. and react for 4 hours;

[0020] (b) Chain extension reaction: After the prepolymerization reaction is completed, turn off the heating and turn on the reflux water to cool the materials to 45°C. At the same time, add the proportion of active chain extender, active end-capping agent, ethyl acetate and isopropanol to another amine material kettle, stir evenly at 45°C, and then transfer the raw materials in the amine material kettle to the main reactor at a uniform speed;

[0021] (c) After the transfer, the material is heated to 50-60°C and reacted for 1 hour before being discharged to obtain the product.

[0022] One application is the use of the polyurethane binder for matte oil prepared by the preparation method of the polyurethane binder for matte oil in preparing gravure ink.

[0023] The beneficial effects of the present invention are as follows: 1. The chain extension is carried out by a two-step method, and the polyhydroxy compound can be first branched and chain extended, and then amino chain extended. In this way, a hyperbranched polyurethane resin containing more urea groups can be synthesized. This structure contains enough relatively hard polyurea bonds. At the same time, the resin main chain is short and the branch chains are many, which ensures that it has advantages such as high matte, good heat resistance, and resistance to finger scratching when it has good solubility in the alcohol ester solvent system. At the same time, it has good strength, and will not have adverse factors such as reverse sticking and sticking to the guide roller during printing and winding;

[0024] Second, using primary amine end-capping agents such as monoethanolamine, benzylamine, tert-butylamine, and octadecylamine together with diamine chain extenders, the molecular weight distribution of the synthesized polyurethane resin is more uniform, and the formulated ink has better stability. In addition, the use of end-capping agents introduces hydroxyl groups, benzene rings, non-polar long carbon chains and other structures on the end groups, which is beneficial to the dispersion of pigments and the adhesion to non-polar substrate films such as BOPP and PE;

[0025] 3. The ratio of isopropyl alcohol: n-propyl acetate: ethyl acetate in the polyurethane ink linker solvent is 2:2:3 or thereabouts. This ratio can make the downstream ink have a good solvent evaporation rate. If the amount of isopropyl alcohol and n-propyl acetate is too much, there will be a lot of solvent residue and the evaporation rate will be too slow, which will cause the ink layer to dry poorly and stick together. If the amount of ethyl acetate is too much, powder aggregation caused by drying too quickly is likely to occur, and printing failures such as knife lines and silking are likely to occur. In addition, n-propyl acetate has a high boiling point and can be used as a solvent in the first step of branching and chain extension to avoid insufficient stirring caused by excessive viscosity during the first step of branching and chain extension.

[0026] The present invention will be described in more detail below with reference to the embodiments. DETAILED DESCRIPTION

[0027] Embodiment 1:

[0028] The polyurethane binder for matte oil described in this embodiment is prepared from 40wt% alcohol-ester soluble polyurethane, 25.8wt% ethyl acetate, 15.4wt% n-propyl acetate and 18.8wt% isopropanol as raw materials. After testing, the viscosity of the polyurethane binder is 1008mPa□s (25°C).

[0029] The method for preparing a polyurethane binder for matte oil ink described in this embodiment includes:

[0030] (a) Prepolymerization: 100 g of 4000 molecular weight poly (1,4-neopentyl adipate) polyol was taken according to the selected ratio and heated to 80° C. 42 g of isophorone diisocyanate was added and stirred and mixed, and then the temperature was raised to 120° C. for reaction for 4 hours;

[0031] (b) Chain extension is carried out by a two-step method: After the prepolymerization reaction is completed, turn off the heating device, turn on the reflux cooling water to cool the prepolymerization kettle to 80°C, and then add 60.1g of n-propyl acetate. Turn on the heating device and control the temperature at 55°C, add 6.5g of trimethylolpropane and 0.05g of dibutyltin dilaurate, quickly stir evenly, and then gradually raise the temperature to 100°C and continue to react for 2 hours for standby use; in another reaction kettle, add 1.5g of isophoronediamine, 2.5g of 1,3-cyclohexanedimethylamine, and 3.5g of octadecylamine in sequence, and dilute with 100.6g of ethyl acetate and 73.3g of isopropanol. Then slowly and evenly transfer the prepolymer to be used to the amine material kettle;

[0032] (c) After the material is transferred, turn on the stirring device and heat it to 50-60°C and react for 1 hour before discharging the material to obtain the product.

[0033] Embodiment 2:

[0034] The polyurethane binder for matte oil described in this embodiment is prepared from 40.5wt% alcohol-ester soluble polyurethane, 25.3wt% ethyl acetate, 15.1wt% n-propyl acetate and 19.1wt% isopropanol as raw materials. After testing, the viscosity of the polyurethane binder is 1123mPa□s (25°C).

[0035] The method for preparing a polyurethane binder for matte oil ink described in this embodiment includes:

[0036] (a) Prepolymerization: 100 g of 4500 molecular weight poly (2-methyl-1,3-propylene glycol) adipate polyol was taken according to the selected ratio and heated to 80° C. 45 g of isophorone diisocyanate was added and stirred and mixed, and then the temperature was raised to 120° C. for reaction for 4 hours;

[0037] (b) Chain extension is carried out by a two-step method: After the prepolymerization reaction is completed, turn off the heating device, turn on the reflux cooling water to cool the prepolymerization kettle to 80°C, and then add 60g of n-propyl acetate. Turn on the heating device and control the temperature at 55°C, add 8.1g of pentaerythritol and 0.05g of dibutyltin dilaurate, quickly stir evenly, gradually raise the temperature to 100°C and continue to react for 2 hours, and set aside; in another reaction kettle, add 1.8g of isophoronediamine, 2.6g of 1,3-cyclohexanedimethylamine, and 3.4g of octadecylamine in sequence, and dilute with 100.5g of ethyl acetate and 75.9g of isopropanol. Then slowly and evenly transfer the prepolymer to be used to the amine material kettle;

[0038] (c) After the material is transferred, turn on the stirring device and heat it to 50-60°C and react for 1 hour before discharging the material to obtain the product.

[0039] Embodiment 3:

[0040] The polyurethane binder for matte oil described in this embodiment is prepared from 39.3wt% alcohol-ester soluble polyurethane, 25.7wt% ethyl acetate, 15.5wt% n-propyl acetate and 19.5wt% isopropanol as raw materials. After testing, the viscosity of the polyurethane binder is 988mPa□s (25°C).

[0041] The method for preparing a polyurethane binder for matte oil ink described in this embodiment includes:

[0042] (a) Prepolymerization: 100 g of 4000 molecular weight butylene terephthalate polyol was taken according to the selected ratio and heated to 80° C., 42 g of isophorone diisocyanate was added and stirred, and then the temperature was raised to 120° C. for reaction for 4 hours;

[0043] (b) Chain extension is carried out by a two-step method: After the prepolymerization reaction is completed, turn off the heating device, turn on the reflux cooling water to cool the prepolymerization kettle to 80°C, and then add 64.4g of n-propyl acetate. Turn on the heating device and control the temperature at 55°C, add 10.3g of glycerol and 0.05g of dibutyltin dilaurate, quickly stir evenly, and then gradually raise the temperature to 100°C and continue to react for 2 hours for standby use; in another reaction kettle, add 2.0g of isophoronediamine, 3.3g of 1,3-cyclohexanedimethylamine, and 5.8g of octadecylamine in sequence, and dilute with 106.9g of ethyl acetate and 84.1g of isopropanol. Then slowly and evenly transfer the prepolymer to be used to the amine material kettle;

[0044] (c) After the material is transferred, turn on the stirring device and heat it to 50-60°C and react for 1 hour before discharging the material to obtain the product.

[0045] Embodiment 4:

[0046] The polyurethane binder for matte oil described in this embodiment is prepared from 39.8wt% alcohol-ester soluble polyurethane, 25.6wt% ethyl acetate, 15.3wt% n-propyl acetate and 19.3wt% isopropanol as raw materials. After testing, the viscosity of the polyurethane binder is 1020mPa□s (25°C).

[0047] The method for preparing a polyurethane binder for matte oil ink described in this embodiment includes:

[0048] (a) Prepolymerization: 100 g of 4000 molecular weight butylene terephthalate polyol was taken according to the selected ratio and heated to 80° C., 42 g of isophorone diisocyanate was added and stirred, and then the temperature was raised to 120° C. for reaction for 4 hours;

[0049] (b) Chain extension is carried out by a two-step method: After the prepolymerization reaction is completed, turn off the heating device, turn on the reflux cooling water to cool the prepolymerization kettle to 80°C, and then add 60.6g of n-propyl acetate. Turn on the heating device and control the temperature at 55°C, add 6.8g of trimethylolpropane and 0.05g of dibutyltin dilaurate, quickly stir evenly, gradually raise the temperature to 100°C and continue to react for 2 hours, and set aside; in another reaction kettle, add 1.7g of isophoronediamine, 2.3g of 1,3-cyclohexanedimethylamine, and 4.8g of octadecylamine in sequence, and dilute with 101.4g of ethyl acetate and 76.4g of isopropanol. Then slowly and evenly transfer the prepolymer to be used to the amine material kettle;

[0050] (c) After the material is transferred, turn on the stirring device and heat it to 50-60°C and react for 1 hour before discharging the material to obtain the product.

[0051] Comparative Example 1:

[0052] This comparative example is a conventional polyurethane binder for ink prepared from 30wt% alcohol ester soluble polyurethane, 35wt% ethyl acetate and 25wt% isopropanol as raw materials. After testing, the viscosity of the polyurethane binder is 1000mPa□s (25°C).

[0053] The preparation method of a conventional polyurethane ink binder described in this comparative example includes:

[0054] (a) Prepolymerization: according to the selected ratio, 100 g of 1000 molecular weight poly (1,4-butanediol) adipate was taken and heated to 60° C., 35.4 g of toluene diisocyanate was added and stirred, and then the temperature was raised to 85° C. for reaction for 4 hours;

[0055] (b) Chain extension reaction: cool the reaction mass to 50-60°C. At the same time, add 15g of isophorone diamine, 175.5g of ethyl acetate and 125g of isopropanol into another amine material kettle, stir evenly at 35°C and transfer the material to the prepolymerization kettle at a uniform speed;

[0056] (c) After the transfer, the material is heated to 50-60°C and reacted for 1 hour before being discharged to obtain the product.

[0057] Example

[0058] The polyurethane resins prepared in the above Examples 1-4 and Comparative Example 1 were respectively prepared into gravure matte oil inks according to the formulas shown in Table 1 below.

[0059] Table 1: Formula of gravure matte oil ink

[0060]

[0061]

[0062] The inks prepared in accordance with Table 1 in the above-mentioned Examples 1-4 and Comparative Example 1 were respectively tested for their application performance. The testing methods refer to the following standards:

[0063] GB / T 7703.1-2008 Determination of transparency of paints and varnishes;

[0064] GBT 13217.4-2008 Test method for viscosity of liquid ink;

[0065] GBT 13217.6-2008 Test method for tinting strength of liquid ink;

[0066] GB / T 21868-2008 Ink General test method for determining the light fastness of ink.

[0067] The application performance test results of the ink are shown in Table 2 below, with the comparative sample as a control.

[0068] Table 2 Performance test results of the ink described

[0069]

[0070]

[0071] The initial viscosity of matte oil ink is generally 20-23 seconds. Ink with such viscosity has good storage stability. It can be seen from the results in the above table that the viscosity of the polyurethane ink binder described in the present invention for matte oil ink is significantly lower than that of the comparative example. After being placed for 7 days, the ink viscosity is also more stable than that of the comparative example, proving that the ink configured in the embodiment has better stability. It has a positive effect on the auxiliary agents such as matte powder in the matte oil system; the mattness of matte oil ink is an important criterion for judging the function of matte oil. As can be seen from the above table, the mattness of Implementation 1-4 has a greater advantage than that of Comparative Example 1. The sample of the present invention has a large molecular weight and high flexibility. It is easy to repair to its original state after the finger scratch test. Compared with Comparative Example 1, the finger scratch resistance performance is obviously greatly improved. The present invention has a high degree of crosslinking and can withstand higher temperatures without changing the form of the substance. As can be seen from the above table, the average heat resistance of Implementation 1-4 can reach about 160°C, which greatly exceeds the heat resistance range of conventional polyurethane resins and meets the needs of polyurethane resins for matte oil. In summary, the polyurethane ink binder of the present invention is more suitable for the performance requirements of polyurethane ink for matte oil and has better comprehensive performance.

[0072] The above is an exemplary description of the present invention. Obviously, the specific implementation of the present invention is not limited to the above method. As long as various improvements are made using the method concept and technical solution of the present invention, or they are directly applied to other occasions without improvement, they all fall within the protection scope of the present invention.

Claims

1. A polyurethane binder for matte oil, characterized in that : The viscosity of the polyurethane connecting material at 25°C is 900-1200mPa□s; The preparation raw materials include raw materials for preparing alcohol-ester soluble polyurethane resin and organic solvent; The total amount of raw materials for preparing the polyurethane connecting material includes:

2. The polyurethane binder for matte oil according to claim 1, characterized in that: The raw materials for preparing the alcohol ester soluble polyurethane resin include the following components in parts by weight:

3. A polyurethane binder for matte oil according to claim 2, characterized in that: The polyester polyol is one or more of neopentyl glycol, ethylene isophthalate, butylene terephthalate, propylene glycol polyol, polyadipate-2-methyl-1,3-propylene glycol polyol, and the average molecular weight of the polyol is 3500-5000.

4. The polyurethane binder for matte oil according to claim 2, characterized in that: The diisocyanate includes a mixture of one or more of isophorone diisocyanate, toluene diisocyanate, 4,4'-diphenylmethane diisocyanate and hexamethylene diisocyanate.

5. A polyurethane connecting material for matte oil according to claim 2, characterized in that the branched chain extender comprises one of pentaerythritol, glycerol and trimethylolpropane.

6. The polyurethane binder for matte oil according to claim 2, characterized in that: The catalyst includes one of dibutyltin dilaurate, tetraisobutyl titanate and triethylamine.

7. The polyurethane binder for matte oil according to claim 2, characterized in that: The amine chain extender includes a mixture of one or more of hydroxyethylethylenediamine, 2-methylpentanediamine, 1,3-cyclohexanedimethylamine and isophoronediamine.

8. The polyurethane binder for matte oil according to claim 2, characterized in that: The end-capping agent includes one or a mixture of monoethanolamine, tert-butylamine, benzylamine and octadecylamine.

9. A method for preparing a polyurethane binder for matte oil, used for preparing the polyurethane binder for matte oil according to any one of claims 1 to 8, characterized in that: Using prepolymerization chain extension method: (a) Prepolymerization: Add the polyol raw material according to the selected ratio into the main reaction kettle and heat it to 80° C., continue to add the isocyanate raw material in the selected ratio and stir and mix, then heat to 95-130° C. and react for 4 hours; (b) Chain extension reaction: After the prepolymerization reaction is completed, turn off the heating and start the reflux water to cool the material to 45°C. At the same time, add a proportion of active chain extender, active end-capping agent, ethyl acetate and isopropanol to another amine material kettle, stir evenly at 45°C, and then transfer the raw materials in the amine material kettle to the main reaction kettle at a uniform speed; (c) After the transfer, the material is heated to 50-60°C and reacted for 1 hour before being discharged to obtain the product.

10. An application, characterized in that: The polyurethane binder for matte oil prepared by the method for preparing the polyurethane binder for matte oil according to any one of claim 9 is used for preparing gravure ink.

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