Water-based paint for pet plastic and preparation method thereof

Abstract

The application discloses a water-based paint for PET plastic and a preparation method thereof. The water-based paint for PET plastic comprises component A and component B. The component A is composed of silicone-modified hydroxyl acrylic resin, polycarbonate polyol, oxalic acid-based polyester polyol, succinic acid / isophthalic acid-based polyester polyol, maleic rosin polyethylene glycol ester, pigment, UV absorber, hindered amine light stabilizer, coupling agent, wetting agent, leveling agent, rheological aid, defoaming agent, accelerator, auxiliary solvent and deionized water. The component B is composed of hexamethylene diisocyanate, isophorone diisocyanate and dilution solvent. The water-based paint provided by the application is sprayed on the surface of a PET bottle, and after being dried into a film, the water-based paint has good adhesion to the PET bottle, is convenient for subsequent printing, electroplating or ion plating, and can effectively improve the water boiling resistance of the PET bottle.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of PET plastic water-based paint and preparation method thereof, belong to PET plastic water-based paint technical field. BACKGROUND

[0002] PET (polyethylene terephthalate) is currently the most commonly used thermoplastic, which is a weakly polar polymer with transparent properties. PET can be produced by injection blow molding, sheet drawing, injection molding, and film blowing processes to produce various bottle products (e.g., water bottles, milk bottles, etc.).

[0003] PET has many shortcomings due to its material characteristics, such as poor water boiling resistance, which causes PET bottles to deform easily when boiled, and PET bottles such as water bottles and milk bottles often need to be boiled for sterilization. In addition, PET also has poor toughness, poor weather resistance, and low surface energy, which results in poor electroplating (or ion plating) performance of PET products and easy brittleness after electroplating. PET bottles often need to be electroplated (or ion plated) for coloring during production. These shortcomings have a significant impact on the application of PET. SUMMARY

[0004] To address the above problems in the prior art, the present application aims to provide a PET plastic water-based paint and a preparation method thereof.

[0005] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0006] A PET plastic water-based paint comprises component A and component B.

[0007] The composition and ratio of component A are as follows:

[0008] Organic silicon modified hydroxy acrylic resin: 35-45 parts by mass;

[0009] Polycarbonate polyol: 25-35 parts by mass;

[0010] Oxalic acid-based polyester polyol: 15-25 parts by mass;

[0011] Sebacic acid / interfertartaric acid-based polyester polyol: 3-8 parts by mass;

[0012] Maleic rosin polyethylene glycol ester: 5-15 parts by mass;

[0013] Pigment: 0-10 parts by mass;

[0014] UV absorber: 2-3 parts by mass;

[0015] Hindered amine light stabilizer: 2-3 parts by mass;

[0016] Coupling agent: 1.5-2.5 parts by mass;

[0017] Wetting agent: 0.5-1.5 parts by mass;

[0018] Leveling agent: 0.5-1.5 parts by mass;

[0019] Rheological aid: 0.5-1.5 parts by mass;

[0020] Defoaming agent: 0.5-1.5 parts by mass;

[0021] Promoter: 0.5-1.5 parts by mass;

[0022] Auxiliary solvent: 5-15 parts by mass;

[0023] Deionized water: 45-55 parts by mass;

[0024] The composition and ratio of the component B are as follows:

[0025] Hexamethylene diisocyanate (HDI for short): 60-70 parts by mass;

[0026] Isophorone diisocyanate (IPDI for short): 30-40 parts by mass;

[0027] Dilution solvent: 5-10 parts by mass.

[0028] In an embodiment, the silicone-modified hydroxyl acrylic resin is obtained by first performing a pre-emulsification reaction on octamethylcyclotetrasiloxane, hydroxyethyl methacrylate, 2-(2H-benzotriazole-2-yl)-6-acryloyloxyhexyl ester, and hexafluorobutyl acrylate, and then performing a polymerization reaction under the action of an initiator.

[0029] In a preferred embodiment, the preparation of the silicone-modified hydroxyl acrylic resin comprises the following steps:

[0030] 1) Pre-emulsification: 20-30 parts by mass of octamethylcyclotetrasiloxane, 30-40 parts by mass of hydroxyethyl methacrylate, 5-10 parts by mass of 2-(2H-benzotriazole-2-yl)-6-acryloyloxyhexyl ester, and 8-12 parts by mass of hexafluorobutyl acrylate are added to a solvent, and emulsified by stirring at 55-65°C for 25-45 minutes;

[0031] 2) Polymerization: the pre-emulsification product is warmed to 80-90°C under nitrogen protection, 0.5-1.5 parts by mass of an initiator is dissolved in a solvent to obtain an initiator solution, and then the initiator solution is slowly added to the pre-emulsification product, after the addition is completed, the reaction is maintained for 3-5 hours;

[0032] 3) post-treatment: cooling the polymerization product to 45-55℃, adding 0.1-0.2 parts by mass of a polymerization inhibitor, removing the solvent under reduced pressure to obtain a silicone-modified hydroxyl acrylic resin.

[0033] In a preferred embodiment, the solvent used in the preparation of the silicone-modified hydroxyl acrylic resin is propylene glycol methyl ether acetate, the total amount of solvent used is 20-40 parts by mass, the initiator used is benzoyl peroxide, and the polymerization inhibitor used is hydroquinone.

[0034] In an embodiment, the maleic rosin polyethylene glycol ester is obtained by reacting maleic rosin and polyethylene glycol in the presence of a catalyst and a water-carrying agent.

[0035] In a preferred embodiment, the preparation of the maleic rosin polyethylene glycol ester comprises the following operations:

[0036] Maleic rosin, polyethylene glycol, catalyst and water-carrying agent are added to a reaction vessel with a water separator, and the reaction is stirred at 235-245℃ under nitrogen protection for 5-7 hours. During the reaction, the water generated by the reaction is removed through the water separator. After the reaction is completed, the reaction product is cooled to below 100℃, and then vacuum extraction is performed to remove the residual water-carrying agent and low-boiling-point substances, thereby obtaining the maleic rosin polyethylene glycol ester.

[0037] In a preferred embodiment, the molar ratio of maleic rosin to polyethylene glycol is 1:2, and the amount of catalyst used is 2% of the mass of maleic rosin.

[0038] In a preferred embodiment, the catalyst is stannous oxalate, and the water-carrying agent is xylene.

[0039] In an embodiment, in component A, the polycarbonate polyol is a polycarbonate diol with a number average molecular weight of 2000 g / mol or a polypropylene carbonate diol with a number average molecular weight of 3000 g / mol.

[0040] In an embodiment, in component A, the UV absorber is 2-hydroxy-4-(2-hydroxyethoxy)benzotriazole, and the hindered amine light stabilizer is 2,2,6,6-tetramethylpiperidine methacrylate.

[0041] In an embodiment, in component A, the pigment is any one of titanium dioxide (e.g., Covestro R-706), iron oxides (e.g., Lanxess Bayferrox 110M), carbon black (e.g., Cabot Monarch 880), phthalocyanine blue / green (e.g., BASF Heliogen Blue L6900), azo red (e.g., Clariant Hostaperm Red E5B), and heterocyclic yellow (e.g., Dainippon Ink Paliotol Yellow L2140), and the coupling agent is KH550 or KH560.

[0042] One embodiment, in component A, the wetting agent is a mixed system of silicone Gemini wetting agent (for example, Tego Glide 450 of Evonik Speciality Chemicals) and acetylenic diol Gemini wetting agent (for example, Venadol 40) with a mass ratio of 1:1; the leveling agent is a silicone leveling agent (for example, Tego Twin 4100 of Evonik Speciality Chemicals); the rheological auxiliary agent is Dispercoll RM-2020 of Evonik; the defoaming agent is TEGO Air 820; the accelerator is an organic bismuth accelerator (for example, Borchi Kat 315).

[0043] One embodiment, the auxiliary solvent in component A and the dilution solvent in component B are both propylene glycol diacetate (PGDA).

[0044] One embodiment, in component B, the hexamethylene diisocyanate is Desmodur 2655 of Covestro, and the isophorone diisocyanate is Vestanat T1890E of Evonik.

[0045] A preparation method of a water-based paint for PET plastic, comprising the following steps:

[0046] a) Preparation of component A:

[0047] Mix a proportioned amount of deionized water, auxiliary solvent and wetting agent uniformly, then add a proportioned amount of pigment and mix uniformly, then add a proportioned amount of silicone-modified hydroxyl acrylic resin, polycarbonate polyol, oxalic acid-based polyester polyol, succinic acid / terephthalic acid-based polyester polyol, maleic rosin polyethylene glycol ester, coupling agent, UV absorber, hindered amine light stabilizer, and mix uniformly, then add a proportioned amount of leveling agent, rheological auxiliary agent, defoaming agent and accelerator, and mix uniformly to obtain component A.

[0048] b) Preparation of component B:

[0049] Mix a proportioned amount of hexamethylene diisocyanate, isophorone diisocyanate and dilution solvent uniformly to obtain component B.

[0050] Compared with the prior art, the present application has the following remarkable beneficial effects:

[0051] The water-based paint provided by the present application is sprayed on the surface of a PET bottle, and after drying and film formation, it has good adhesion to the PET bottle, can provide a good adhesion layer on the surface of the PET bottle, and is convenient for subsequent printing, electroplating or ion plating, in addition, can effectively improve the water boiling resistance of the PET bottle, has high social use value and application prospect. DETAILED DESCRIPTION

[0052] The technical solutions of the present application will be further described in detail below in combination with examples. It should be understood that these examples are only used to illustrate the present application and not to limit the scope of the present application. The experimental methods not specified in the following examples are generally carried out according to the conventional conditions or according to the conditions recommended by the manufacturers. Example 1

[0053] I. Preparation of silicone-modified hydroxyl acrylic resin

[0054] 1) Pre-emulsification: 25 parts by mass of octamethylcyclotetrasiloxane, 35 parts by mass of hydroxyethyl methacrylate, 8 parts by mass of 2-(2H-benzotriazole-2-yl)-6-acryloyloxyhexyl ester, and 10 parts by mass of hexafluorobutyl acrylate were added to 20 parts by mass of propylene glycol methyl ether acetate, and the mixture was stirred and emulsified at 60°C for 30 minutes;

[0055] 2) Polymerization: the pre-emulsified product was warmed to 85°C under nitrogen protection, 0.8 parts by mass of initiator benzoyl peroxide was dissolved in 5 parts by mass of propylene glycol methyl ether acetate to obtain an initiator solution, and then the initiator solution was slowly added to the pre-emulsified product. After the addition was completed, the reaction was maintained for 4 hours;

[0056] 3) Post-treatment: the polymerized product was cooled to 50°C, 0.1 parts by mass of polymerization inhibitor hydroquinone was added, and the solvent was removed by distillation under reduced pressure to obtain the silicone-modified hydroxyl acrylic resin.

[0057] II. Preparation of maleic rosin polyethylene glycol ester

[0058] 400g of maleic rosin, 800g of polyethylene glycol (PEG-400), 8g of catalyst stannous oxalate, and 120ml of water-carrying agent xylene were added to a reaction vessel with a water separator, and stirred at 240°C under nitrogen protection for 6 hours. During the reaction, the water generated by the reaction was removed through the water separator. After the reaction was completed, the temperature was cooled to below 100°C, and then the reaction product was vacuumed to remove the residual water-carrying agent and low-boiling-point substances to obtain the maleic rosin polyethylene glycol ester.

[0059] III. Preparation of water-based paint

[0060] a) Preparation of Component A:

[0061] 50 parts by mass of deionized water, 10 parts by mass of an auxiliary solvent (PGDA), 0.5 parts by mass of a silicone gemini wetting agent (Tego Glide 450), 0.5 parts by mass of an acetylenic diol gemini wetting agent (Venadol 40) were stirred and mixed uniformly, then 5 parts by mass of pigment azo red (Ciba Hostaperm Red E5B) was added, stirred and mixed uniformly, then 35 parts by mass of silicone-modified hydroxyl acrylate resin, 25 parts by mass of polycarbonate polyol (polycarbonate diol with a number average molecular weight of 2000 g / mol), 20 parts by mass of oxalic acid-based polyester polyol (Asahi Chemical XCP-2000PM), 5 parts by mass of eleostearic acid / isophthalic acid-based polyester polyol (Asahi Chemical XCP-2000IPS), 15 parts by mass of maleic rosin polyethylene glycol ester, 2 parts by mass of coupling agent (KH550), 2.5 parts by mass of UV absorber (2-hydroxy-4-(2-hydroxyethoxy)benzotriazole), 2.5 parts by mass of hindered amine light stabilizer (methyl methacrylate-2,2,6,6-tetramethylpiperidyl ester) were stirred and mixed uniformly, then 1 part by mass of leveling agent (Wincrete Special Chemicals Tego Twin 4100), rheological aid (Evonik Acrysol RM-2020), 1 part by mass of defoaming agent (TEGO Air 820), 1 part by mass of accelerator (Borchi Kat 315) were stirred and mixed uniformly to obtain component A.

[0062] b) Preparation of component B:

[0063] 60 parts by mass of hexamethylene diisocyanate (Evonik Desmodur 2655), 40 parts by mass of isophorone diisocyanate (Wincrete Vestanat T1890E), and 8 parts by mass of dilution solvent (PGDA) were stirred and mixed uniformly to obtain component B.

[0064] Example 2

[0065] The difference between this example and Example 1 is:

[0066] In component A, the polyol combination used was: 40 parts by mass of silicone-modified hydroxyl acrylate resin, 30 parts by mass of polycarbonate polyol (polypropylene carbonate diol with a number average molecular weight of 3000 g / mol), 15 parts by mass of oxalic acid-based polyester polyol (Asahi Chemical XCP-2000PM), 5 parts by mass of eleostearic acid / isophthalic acid-based polyester polyol (Asahi Chemical XCP-2000IPS), 10 parts by mass of maleic rosin polyethylene glycol ester; the pigment used was titanium dioxide (Cromogen R-706);

[0067] In component B, the isocyanate combination used was: 65 parts by mass of hexamethylene diisocyanate, 35 parts by mass of isophorone diisocyanate.

[0068] Example 3

[0069] The difference between this example and Example 1 is that:

[0070] In component A, the polyol combination used was: 45 parts by mass of silicone-modified hydroxyl acryl resin, 25 parts by mass of polycarbonate polyol (polypropylene carbonate diol with a number average molecular weight of 3000 g / mol), 20 parts by mass of oxalic acid-based polyester polyol (Asahi Chemical XCP-2000PM), 5 parts by mass of maleic rosin polyethylene glycol ester; in addition, no pigment was contained (i.e., 0 parts by mass of pigment), and the coupling agent used was KH560;

[0071] In component B, the isocyanate combination used was: 70 parts by mass of hexamethylene diisocyanate, 30 parts by mass of isophorone diisocyanate.

[0072] Comparative Example 1

[0073] The difference between this comparative example and Example 1 is that:

[0074] In component A, the polyol combination used was: 50 parts by mass of hydroxyl acryl resin, 25 parts by mass of polycarbonate polyol (polycarbonate diol with a number average molecular weight of 2000 g / mol), 25 parts by mass of oxalic acid-based polyester polyol (Asahi Chemical XCP-2000PM).

[0075] Comparative Example 2

[0076] The difference between this comparative example and Example 1 is that:

[0077] In component A, the polyol combination used was: 55 parts by mass of hydroxyl acryl resin, 45 parts by mass of oxalic acid-based polyester polyol (Asahi Chemical XCP-2000PM); the wetting agent used was 1 part by mass of polyether-modified silicone-based wetting agent (BYK 345).

[0078] Performance Test:

[0079] After mixing component A and component B in a mass ratio of 4:1, they were sprayed onto the surface of a PET bottle, with a wet film thickness of 15 μm. After film formation, the surface was first allowed to dry at room temperature for 15 minutes, and then baked at 60°C for 35-40 minutes, to form a polyurethane paint film on the surface of the PET bottle.

[0080] The adhesion thereof is tested by using the crosshatch method; the bottle is immersed in 60℃ deionized water for two hours to test the water boiling resistance thereof; the general electroplating process is used for electroplating experiment to evaluate whether it is applicable to printing electroplating coloring; and the test results are shown in Table 1.

[0081] Table 1 Test data of the water-based paint prepared in Examples 1-3 and Comparative Examples 1-2

[0082]

[0083] As shown in Table 1, the water-based paint prepared in Examples 1-3 has better adhesion, water boiling resistance and electroplating performance than the water-based paint of Comparative Example 1-2.

[0084] In summary, the water-based paint provided by Examples 1-3 has better adhesion with PET than the water-based paint of Comparative Example 1-2, and after being sprayed on the surface of the PET bottle, it can effectively improve the water boiling resistance of the PET bottle and make the PET bottle easy to be electroplated (or ion plated) for coloring, which may be because: the organic silicon modified hydroxyl acrylic resin used in Examples 1-3 has significantly better hydrophobicity, flexibility and compatibility with PET than the ordinary hydroxyl acrylic resin of Comparative Example 1-2, thereby improving the adhesion (enhancing the interfacial bonding through Si-O bond) and water resistance (organic silicon segment blocking water molecules from penetrating); the maleic rosin polyethylene glycol ester added in Examples 1-3 can significantly improve the flexibility of the paint film and enhance the adhesion with PET, while Comparative Example 1-2 lacks this component, resulting in increased brittleness and decreased adhesion; a plurality of types of polyols are used in Examples 1-3, and the synergistic effect between the polyols can provide balanced hardness and flexibility, while the polyol types in Comparative Example 1-2 are relatively single; the wetting agent used in Examples 1-3 is a compound of siloxane gemini wetting agent and alkyne diol gemini wetting agent, which can significantly reduce the surface tension, improve the spreading property of the PET surface and has better wetting effect, thereby effectively improving the adhesion with PET.

[0085] Finally, it needs to be pointed out that: the above is only some preferred embodiments of the present application, and cannot be understood as a limitation on the protection scope of the present application, and some non-essential improvements and adjustments made by those skilled in the art according to the above content of the present application are all within the protection scope of the present application.

Claims

1. A water-based paint for a PET plastic, characterized by comprising: Component A and Component B; The composition and proportion of the Component A are as follows: Silicone-modified hydroxyl acrylic resin: 35-45 parts by mass; Polycarbonate polyol: 25-35 parts by mass; Adipic acid-based polyester polyol: 15-25 parts by mass; Sebacic acid / isophthalic acid-based polyester polyol: 3-8 parts by mass; Maleic rosin polyethylene glycol ester: 5-15 parts by mass; Pigment: 0-10 parts by mass; UV absorber: 2-3 parts by mass; Hindered amine light stabilizer: 2-3 parts by mass; Coupling agent: 1.5-2.5 parts by mass; Wetting agent: 0.5-1.5 parts by mass; Leveling agent: 0.5-1.5 parts by mass; Rheological aid: 0.5-1.5 parts by mass; Defoaming agent: 0.5-1.5 parts by mass; Promoter: 0.5-1.5 parts by mass; Auxiliary solvent: 5-15 parts by mass; Deionized water: 45-55 parts by mass; The composition and proportion of the Component B are as follows: Hexamethylene diisocyanate: 60-70 parts by mass; Isophorone diisocyanate: 30-40 parts by mass; Dilution solvent: 5-10 parts by mass; The silicone-modified hydroxyl acrylic resin is obtained by pre-emulsifying octamethylcyclotetrasiloxane, hydroxyethyl methacrylate, 2-(2H-benzotriazole-2-yl)-6-acryloyloxyhexyl ester, and hexafluorobutyl acrylate, and then polymerizing under the action of an initiator.

2. The water-based paint for a PET plastic according to claim 1, characterized by The preparation of the silicone-modified hydroxyl acrylic resin includes the following steps: 1) Pre-emulsification: 20-30 parts by mass of octamethylcyclotetrasiloxane, 30-40 parts by mass of hydroxyethyl methacrylate, 5-10 parts by mass of 2-(2H-benzotriazole-2-yl)-6-acryloyloxyhexyl ester, and 8-12 parts by mass of hexafluorobutyl acrylate are added to a solvent, and emulsified under stirring at 55-65°C for 25-45 minutes; 2) Polymerization: the pre-emulsified product is warmed to 80-90°C under nitrogen protection, 0.5-1.5 parts by mass of an initiator is dissolved in a solvent to obtain an initiator solution, and then the initiator solution is slowly added to the pre-emulsified product, after the addition is completed, the reaction is maintained for 3-5 hours; 3) Post-treatment: the polymerized product is cooled to 45-55°C, 0.1-0.2 parts by mass of a polymerization inhibitor is added, and the solvent is removed by distillation under reduced pressure to obtain the silicone-modified hydroxyl acrylic resin.

3. The water-based paint for a PET plastic according to claim 1, characterized by: The maleic rosin polyethylene glycol ester is obtained by reacting maleic rosin and polyethylene glycol under the action of a catalyst and a water-carrying agent.

4. The water-based paint for a PET plastic according to claim 3, characterized by The preparation of the maleic rosin polyethylene glycol ester includes the following operations: Maleic rosin, polyethylene glycol, a catalyst, and a water-carrying agent are added to a reaction container with a water separator, stirred at 235-245°C under nitrogen protection for 5-7 hours, the water generated during the reaction is removed through the water separator during the reaction, after the reaction is completed, the temperature is lowered to below 100°C, then the reaction product is vacuumized to remove the residual water-carrying agent and low-boiling-point substances, and the maleic rosin polyethylene glycol ester is obtained.

5. The water-based paint for a PET plastic according to claim 4, characterized by: The molar ratio of maleic rosin to polyethylene glycol is 1:2, and the amount of the catalyst is 2% of the mass of maleic rosin.

6. The water-based paint for a PET plastic according to claim 1, characterized by: In component A, the polycarbonate polyol is a polycarbonate diol with a number average molecular weight of 2000 g / mol or a polypropylene carbonate diol with a number average molecular weight of 3000 g / mol.

7. The water-based paint for a PET plastic according to claim 1, characterized by: In component A, the wetting agent is a mixed system of a silicone gemini wetting agent and an alkyne diol gemini wetting agent with a mass ratio of 1:

1.

8. The water-based paint for a PET plastic according to claim 1, characterized by: Both the auxiliary solvent in component A and the dilution solvent in component B are propylene glycol diacetate.

9. A method for preparing a water-based paint for PET plastic as described in claim 1, characterized in that, The method comprises the following steps: a) Preparation of component A: Mix a proportioned amount of deionized water, auxiliary solvent, and wetting agent uniformly, then add a proportioned amount of pigment, mix uniformly, then add a proportioned amount of silicone-modified hydroxyl acrylic resin, polycarbonate polyol, oxalic acid-based polyester polyol, sebacic acid / m-terephthalic acid-based polyester polyol, maleic rosin polyethylene glycol ester, coupling agent, UV absorber, hindered amine light stabilizer, mix uniformly, then add a proportioned amount of leveling agent, rheological aid, defoaming agent, and accelerator, mix uniformly to obtain component A; b) Preparation of component B: Mix a proportioned amount of hexamethylene diisocyanate, isophorone diisocyanate, and dilution solvent uniformly to obtain component B.

Images