阅读说明：本技术 一种超延时机械性能的聚酯树脂及其制备方法和应用 (Polyester resin with super-delayed mechanical property and preparation method and application thereof ) 是由 汪俊 于 2021-09-01 设计创作，主要内容包括：本发明提供了一种超延时机械性能的聚酯树脂及其制备方法和应用,成分：多元醇：31-41％wt；芳香多元酸42-53％wt；支化剂：0.01-1.5％wt；酸解剂：11-16％wt；酯化催化剂：0.03-0.15％wt；抗氧剂0.01-1.5％wt；固化促进剂0.01-1％wt；增韧剂0.1-3％wt。酸值38-43mgKOH/g,羟值6-10mgKOH/g,粘度4000-6000mPa.s,玻璃化温度≥65℃,数均分子量3000-4500g/mol；具有更优异的机械性能和延时机械性能。(The invention provides a polyester resin with super time-delay mechanical property and a preparation method and application thereof, and the polyester resin comprises the following components: polyol: 31-41% wt; 42-53 wt% of aromatic polybasic acid; branching agent: 0.01-1.5% wt; acid hydrolysis agent: 11-16% wt; esterification catalyst: 0.03 to 0.15% wt; 0.01 to 1.5 percent of antioxidant; 0.01-1 wt% of curing accelerator; 0.1 to 3 weight percent of toughening agent. The acid value is 38-43mgKOH/g, the hydroxyl value is 6-10mgKOH/g, the viscosity is 4000-; has more excellent mechanical property and delayed mechanical property.)

1. The polyester resin with super time-delay mechanical property is characterized by comprising the following raw materials in percentage by mass:

polyol: 31-41% wt; 42-53 wt% of aromatic polybasic acid; branching agent: 0.01-1.5% wt; acid hydrolysis agent: 11-16% wt; esterification catalyst: 0.03 to 0.15% wt; 0.01 to 1.5 percent of antioxidant; 0.01-1 wt% of curing accelerator; 0.1 to 3 weight percent of toughening agent.

2. The polyester resin with super delayed mechanical properties according to claim 1, wherein the polyol is selected from one or a combination of two or more of neopentyl glycol (NPG), Ethylene Glycol (EG), methyl propylene glycol (MPDI), and Cyclohexanedimethanol (CHDM).

3. The polyester resin with super delayed mechanical property according to claim 1, wherein the aromatic polybasic acid is selected from one or two of terephthalic acid (PTA) and isophthalic acid (IPA).

4. The polyester resin having super delayed mechanical properties according to claim 1, wherein the acid hydrolysis agent is one or a combination of two or more selected from isophthalic acid (IPA), adipic acid (ADA), trimellitic anhydride (TMA)1,4 cyclohexanedicarboxylic acid (CHDA), fumaric acid (FCC), succinic acid (BA) and dodecanedioic acid (DDDA).

5. The polyester resin with super delayed mechanical property according to claim 1, wherein the antioxidant is compounded by phosphite ester and hindered phenol antioxidant.

6. The polyester resin with super delayed mechanical properties according to claim 1, wherein the toughening agent is Griltex D2132E of EMS company of Switzerland.

7. A process for preparing the polyester resin with super delayed mechanical properties according to any one of claims 1 to 6, comprising the steps of:

1) putting the polyol, the branching agent, the aromatic polybasic acid and the esterification catalyst with the formula ratio into a reaction kettle, filling nitrogen, heating to 250 ℃ and maintaining, adding the acidolysis agent when the Acid Value (AV) reaches 8-12mgKOH/g after the system is clarified, and maintaining the temperature at 235 ℃ and 245 ℃ for acidolysis and end capping;

2) cooling and vacuumizing when the acid value of the polyester reaches 48-55mgKOH/g, so that the reactants are polycondensed, the acid value of the polyester reaches 38-43mgKOH/g, the hydroxyl value is 6-10mgKOH/g, and the viscosity is 4000-6000 mPa.s;

3) and finally, cooling, adding the antioxidant, the curing accelerator and the toughening agent in the formula amount, maintaining for 20-30min, and discharging.

8. The method as claimed in claim 7, wherein the temperature reduction in step 2) is performed by cooling to 230 ℃ and performing vacuum polycondensation for 90-120 minutes.

9. The method as claimed in claim 7 or 8, wherein the temperature reduction in step 3) is to 190-200 ℃.

10. Use of the polyester resin with ultra-delayed mechanical properties according to any one of claims 1 to 6 for the preparation of powder coatings with ultra-delayed mechanical properties.

Technical Field

The invention belongs to the field of polyester resin, and particularly relates to polyester resin with super-delayed mechanical property, and a preparation method and application thereof.

Background

The powder coating is used as an environment-friendly coating and is applied to various fields, such as household appliances, building materials, automobile parts, MDF plates, various hardware and the like. Although the environmental protection property, the cost performance, the weather resistance and the like of the powder coating are outstanding, the problems which cannot be completely solved in the prior art exist, for example, after the powder coating is sprayed on a workpiece, the mechanical property of the coating is attenuated in later processing, and the phenomena of cracking, paint collapse and even large-area coating falling off occur on the coating at the processing part of the workpiece and in the nearby area.

In order to improve the phenomenon, a powder coating manufacturer can only add a curing accelerator when designing a formula, improve the curing temperature and prolong the curing time, and aims to ensure that the coating is cured more completely, so that the manufacturer can process a workpiece as soon as possible in a short period after the spraying and curing are finished, and the mechanical property of the coating is prevented from being attenuated too fast.

CN 108084418A polyester resin disclosed in 2018, 5, 29 and the solution proposed in the preparation method thereof is to prepare polyester resin with two functions of carboxyl and hydroxyl, and then to use two curing agents to react with the carboxyl and the hydroxyl respectively when preparing powder coating.

Disclosure of Invention

The invention aims to provide a polyester resin with super-long time-delay mechanical property and a preparation method thereof, the polyester resin mainly comprises carboxyl functional groups and proper amount of hydroxyl functional groups, the hydroxyl value of the hydroxyl functional groups is controlled between 6 mgKOH/g and 10mgKOH/g, because the hydroxyl groups can be combined with hydrogen bonds on the surface of a workpiece, a coating and the substrate of the workpiece form better chemical linking force, and the polyester resin with super-long time-delay mechanical property is obtained through the formula optimization and the process control of the polyester resin.

The invention also aims to provide application of the polyester resin with super delayed mechanical property in coating.

The specific technical scheme of the invention is as follows:

the polyester resin with super time-delay mechanical properties comprises the following raw materials in percentage by mass:

polyol: 31-41% wt; 42-53 wt% of aromatic polybasic acid; branching agent: 0.01-1.5% wt; acid hydrolysis agent: 11-16% wt; esterification catalyst: 0.03 to 0.15% wt; 0.01 to 1.5 percent of antioxidant; 0.01-1 wt% of curing accelerator; 0.1 to 3 weight percent of toughening agent.

The total mass percentage of the raw materials is 100 percent.

The polyalcohol is one or a composition of more than two of neopentyl glycol (NPG), Ethylene Glycol (EG), methyl propylene glycol (MPDI) and 1, 4-Cyclohexanedimethanol (CHDM); more preferred are two or more polyols including neopentyl glycol (NPG); NPG has the advantages of water resistance, chemical resistance, weather resistance and the like, but the cost is higher than that of other (EG, MPDI, DEG and the like) alcohols, and the raw materials are comprehensively considered from the aspects of the performance and price of the synthesized polyester;

the aromatic polybasic acid is selected from one or two of terephthalic acid (PTA) and isophthalic acid (IPA); more preferred are compositions comprising IPA and PTA; the IPA content is controlled to be 10-50% of the total mass of the aromatic polybasic acid, the IPA has excellent weather resistance, the content is too low, the weather resistance is poor, and the mechanical property is poor when the content is too high;

the acidolysis agent is one or a composition of more than two of isophthalic acid (IPA), adipic acid (ADA), trimellitic anhydride (TMA), 1,4 cyclohexanedicarboxylic acid (CHDA), fumaric acid (FCC), succinic acid (BA) or dodecanedioic acid (DDDA); more preferred are two or more compositions comprising isophthalic acid (IPA), adipic acid (ADA);

the branching agent is one or two mixtures of Trimethylolpropane (TMP) and Trimethylolethane (TME); more preferably, one or both compositions comprising TMP are used;

the antioxidant adopts a mode of compounding phosphite ester and hindered phenol antioxidant, and the weight ratio of the phosphite ester to the hindered phenol antioxidant is 1: 1; the phosphite antioxidant is bis (2, 4-di-tert-butylphenyl) pentaerythritol diphosphite (antioxidant 626), and the hindered phenol antioxidant is tetrakis [ beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate ] pentaerythritol ester (antioxidant 1010);

the curing accelerator is one or a composition of more than two of tetraethylammonium bromide, tetramethylammonium bromide, benzyltriethylammonium chloride, triphenyl ethyl phosphine bromide or dibutyltin dilaurate;

the esterification catalyst is a tin catalyst, preferably one or more of dibutyltin oxide, tributyltin oxide, dihydroxybutyltin chloride, stannous oxalate or monobutyltin oxide, and more preferably one or more of a composition containing monobutyltin oxide;

the toughening agent is Griltex D2132E of Switzerland EMS company.

The invention provides a preparation method of polyester resin with super time-delay mechanical property, which comprises the following steps:

1) putting the polyol, the branching agent, the aromatic polybasic acid and the esterification catalyst with the formula ratio into a reaction kettle, filling nitrogen, heating to 250 ℃ and maintaining, adding the acidolysis agent when the Acid Value (AV) reaches 8-12mgKOH/g after the system is clarified, and maintaining the temperature at 235 ℃ and 245 ℃ for acidolysis and end capping;

2) cooling and vacuumizing when the acid value of the polyester reaches 48-55mgKOH/g, so that the reactants are polycondensed, the acid value of the polyester reaches 38-43mgKOH/g, the hydroxyl value is 6-10mgKOH/g, and the viscosity is 4000-6000 mPa.s;

3) and finally, cooling, adding the antioxidant, the curing accelerator and the toughening agent in the formula amount, maintaining for 20-30min, and discharging.

The nitrogen is filled all the time in the heating process in the step 1), because the materials are easily oxidized in the heating process, the purpose of filling the nitrogen is to remove the air in the reaction kettle, because the reaction kettle for synthesizing the polyester is usually normal pressure, the nitrogen is required to be filled all the time in the heating process for protection, and the nitrogen cannot be filled in the later vacuum-pumping stage because the nitrogen is in a negative pressure state.

In the process of raising the temperature to 240-250 ℃ in the step 1), in order to prevent the alcohol in the formula from losing from the top end of the reflux tower after being gasified at high temperature, the temperature raising rate is generally actually controlled according to the temperature at the top end of the reflux tower, and the temperature at the top end of the reflux tower is kept less than 105 ℃;

the temperature reduction in the step 2) refers to temperature reduction to 220-230 ℃, and vacuum-pumping polycondensation reaction is carried out for 90-120 minutes.

The step 2) is to use a vacuum pump (0.1MPA) of Germany BUSCH for vacuumizing;

the vacuum pump of German BUSCH is used in the invention, the vacuum degree is 0.1MPA, and the time is 90-120 minutes, thereby achieving the purposes that the acid value of the following polyester reaches 38-43mgKOH/g, the hydroxyl value is 6-10mgKOH/g, and the viscosity is 4000-6000 mPa.s.

The temperature reduction in the step 3) is to be 190-200 ℃.

The polyester resin with super-delayed mechanical property finally prepared by the invention has the following important indexes: the acid value is 38-43mgKOH/g, the hydroxyl value is 6-10mgKOH/g, the viscosity is 4000-6000mPa.s, the glass transition temperature is more than or equal to 65 ℃, and the number average molecular weight is 3000-4500 g/mol.

The invention provides an application of polyester resin with super time-delay mechanical property, which is used for preparing powder coating with super time-delay mechanical property.

The specific method for preparing the powder coating is as follows:

the curing agent used for preparing the powder coating by the polyester resin with super delayed mechanical property is triglycidyl isocyanurate (TGIC);

the mass ratio of the polyester resin with super time-delay mechanical property to the triglycidyl isocyanurate is 92: 8;

the powder coating comprises the following raw materials: polyester resin with super time-delay mechanical property, curing agent, pigment, filler, flatting agent and benzoin to finally obtain the powder coating with super time-delay mechanical property.

The polyester resin with super delayed mechanical property provided by the invention has an acid value of 38-43mgKOH/g, so that the curing ratio of the polyester resin to TGIC is 92:8 (referring to the mass ratio of the polyester resin to the curing agent TGIC), and the prepared powder coating has higher crosslinking density than that of a conventional powder coating (the mass ratio of the polyester resin to the curing agent TGIC of the conventional powder coating is 93: 7); because the hydroxyl value of the polyester resin is 6-10mgKOH/g, the hydroxyl in the prepared powder coating can be combined with the hydrogen bond on the surface of a workpiece, so that the coating and the substrate of the workpiece form better chemical linking force, and compared with the conventional powder coating, the powder coating has better adhesive force with the substrate of the workpiece; because the polyester resin is controlled by a better vacuum pump and process (the vacuum degree of a common vacuum pump is difficult to reach the required 0.1MPA, the vacuum efficiency is low, the molecular weight and the molecular weight distribution are difficult to achieve the preset target in the polycondensation stage of polyester synthesis), the molecular weight of the polyester resin is 3000-4500g/mol, the molecular weight distribution coefficient is less than or equal to 1.8, compared with the conventional polyester resin, the molecular weight is higher, meanwhile, the content of the small molecular polymer is less, the molecular weight distribution is more uniform, and therefore, the prepared powder coating has more excellent mechanical property and delayed mechanical property; compared with the conventional polyester resin, the polyester resin is added with the toughening agent, so that the prepared powder coating has more excellent flexibility compared with the conventional powder coating, and the delayed mechanical property of the powder coating is further improved.

Compared with the prior art, the polyester resin provided by the invention has the main reaction functional group of carboxyl functional group and also contains proper amount of hydroxyl functional group, the hydroxyl value of the hydroxyl functional group is controlled between 6 mgKOH/g and 10mgKOH/g, because the hydroxyl can be combined with the hydrogen bond on the surface of the workpiece, the coating and the substrate of the workpiece form better chemical linking force, the polyester resin has more concentrated molecular weight and contains proper proportion of linear molecular chain by formula optimization and process control of the polyester resin, the flexibility of the polyester resin is improved, and the flexibility and the delayed mechanical property of the polyester resin are further improved by adding proper amount of flexibilizer at the final stage of polyester synthesis.

Detailed Description

The present invention will be described in further detail with reference to examples.

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Test materials, reagents and the like used in the following examples are commercially available unless otherwise specified.

The specific techniques or conditions not specified in the examples can be performed according to the techniques or conditions described in the literature in the field or according to the product specification.

The polyester resin with super time-delay mechanical properties comprises the following raw materials in percentage by mass:

polyol: 31-41% wt; 42-53 wt% of aromatic polybasic acid; branching agent: 0.01-1.5% wt; acid hydrolysis agent: 11-16% wt; esterification catalyst: 0.03 to 0.15% wt; 0.01 to 1.5 percent of antioxidant; 0.01-1 wt% of curing accelerator; 0.1 to 3 weight percent of toughening agent.

The total mass percentage of the raw materials is 100 percent.

The polyalcohol is one or a composition of more than two of neopentyl glycol (NPG), Ethylene Glycol (EG), methyl propylene glycol (MPDI) and 1, 4-Cyclohexanedimethanol (CHDM); more preferred are two or more polyols including neopentyl glycol (NPG);

the aromatic polybasic acid is selected from one or two of terephthalic acid (PTA) and isophthalic acid (IPA); more preferred are compositions comprising IPA and PTA; the IPA content is controlled to be 10-50% of the total mass of the aromatic polybasic acid;

the acidolysis agent is one or a composition of more than two of isophthalic acid (IPA), adipic acid (ADA), trimellitic anhydride (TMA), 1,4 cyclohexanedicarboxylic acid (CHDA), fumaric acid (FCC), succinic acid (BA) or dodecanedioic acid (DDDA); more preferred are two or more compositions comprising isophthalic acid (IPA), adipic acid (ADA);

the branching agent is one or two mixtures of Trimethylolpropane (TMP) and Trimethylolethane (TME); more preferably, one or both compositions comprising TMP are used;

the antioxidant adopts a mode of compounding phosphite ester and hindered phenol antioxidant, and the weight ratio of the phosphite ester to the hindered phenol antioxidant is 1: 1; the phosphite antioxidant is bis (2, 4-di-tert-butylphenyl) pentaerythritol diphosphite (antioxidant 626), and the hindered phenol antioxidant is tetrakis [ beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate ] pentaerythritol ester (antioxidant 1010);

the curing accelerator is one or a composition of more than two of tetraethylammonium bromide, tetramethylammonium bromide, benzyltriethylammonium chloride, triphenyl ethyl phosphine bromide or dibutyltin dilaurate;

the esterification catalyst is a tin catalyst, preferably one or more of dibutyltin oxide, tributyltin oxide, dihydroxybutyltin chloride, stannous oxalate or monobutyltin oxide, and more preferably one or more of a composition containing monobutyltin oxide;

the toughening agent is Griltex D2132E of Switzerland EMS company.

The preparation method of the polyester resin with super delayed mechanical property comprises the following steps:

1) putting the polyol, the branching agent, the aromatic polybasic acid and the esterification catalyst with the formula ratio into a reaction kettle, filling nitrogen, heating to 250 ℃ and maintaining, adding the acidolysis agent when the Acid Value (AV) reaches 8-12mgKOH/g after the system is clarified, and maintaining the temperature at 235 ℃ and 245 ℃ for acidolysis and end capping;

2) cooling and vacuumizing when the acid value of the polyester reaches 48-55mgKOH/g, so that the reactants are polycondensed, the acid value of the polyester reaches 38-43mgKOH/g, the hydroxyl value is 6-10mgKOH/g, and the viscosity is 4000-6000 mPa.s;

3) and finally, cooling, adding the antioxidant, the curing accelerator and the toughening agent in the formula amount, maintaining for 20-30min, and discharging.

The nitrogen is filled all the time in the heating process in the step 1), because the materials are easily oxidized in the heating process, the purpose of filling the nitrogen is to remove the air in the reaction kettle, because the reaction kettle for synthesizing the polyester is usually normal pressure, the nitrogen is required to be filled all the time in the heating process for protection, and the nitrogen cannot be filled in the later vacuum-pumping stage because the nitrogen is in a negative pressure state.

In the process of raising the temperature to 240-250 ℃ in the step 1), in order to prevent the alcohol in the formula from losing from the top end of the reflux tower after being gasified at high temperature, the temperature raising rate is generally actually controlled according to the temperature at the top end of the reflux tower, and the temperature at the top end of the reflux tower is kept less than 105 ℃;

the temperature reduction in the step 2) refers to temperature reduction to 220-230 ℃, and vacuum-pumping polycondensation reaction is carried out for 90-120 minutes.

The step 2) is to use a vacuum pump (0.1MPA) of Germany BUSCH for vacuumizing;

the vacuum pump of German BUSCH is used in the invention, the vacuum degree is 0.1MPA, and the time is 90-120 minutes, thereby achieving the purposes that the acid value of the following polyester reaches 38-43mgKOH/g, the hydroxyl value is 6-10mgKOH/g, and the viscosity is 4000-6000 mPa.s.

The temperature reduction in the step 3) is to be 190-200 ℃.

The polyester resin with super-delayed mechanical property finally prepared by the invention has the following important indexes: the acid value is 38-43mgKOH/g, the hydroxyl value is 6-10mgKOH/g, the viscosity is 4000-6000mPa.s, the glass transition temperature is more than or equal to 65 ℃, and the number average molecular weight is 3000-4500 g/mol.

The invention provides an application of polyester resin with super time-delay mechanical property, which is used for preparing powder coating with super time-delay mechanical property.

The specific method for preparing the powder coating is as follows:

the curing agent used for preparing the powder coating by the polyester resin with super delayed mechanical property is triglycidyl isocyanurate (TGIC);

the mass ratio of the polyester resin with super time-delay mechanical property to the triglycidyl isocyanurate is 92: 8;

the powder coating comprises the following raw materials: polyester resin with super time-delay mechanical property, curing agent, pigment, filler, flatting agent and benzoin to finally obtain the powder coating with super time-delay mechanical property.

In Table 1, there are important indices of selection and amount of raw materials for the polyester resin of the specific example 1(A), example 2(B), example 3(C), and example 4(D), and the corresponding amounts.

The preparation method of the embodiment of the invention comprises the following steps: in a 5L glass reaction kettle, putting the polyol, the branching agent, the aromatic polybasic acid and the esterification catalyst which are in the formula amount of each example in the table 1 into the reaction kettle at the same time, charging nitrogen, slowly heating to 250 ℃ and maintaining, adding the acidolysis agent when the sampling detection Acid Value (AV) reaches 8-12mgKOH/g after the system is clarified, and maintaining the temperature at 235 ℃ and 245 ℃ for acidolysis and end capping; cooling to 230 ℃ when the acid value of the polyester reaches 48-55mgKOH/g, and vacuumizing by using a vacuum pump (0.1MPA) of Germany BUSCH to perform polycondensation on the reactants for 90-120 minutes, so that the acid value of the polyester reaches 38-43mgKOH/g, the hydroxyl value is 6-10, and the viscosity is 4000-6000 mPa.s; then cooling to 190-200 ℃, adding an antioxidant, a curing accelerator and a toughening agent, and discharging after maintaining for 20-30 min; wherein the acid value control indexes at different stages are also shown in Table 1. For further comparison, two general resin E and F indices in the industry are provided for comparison, comparative example 1 and comparative example 2, respectively.

TABLE 1 formulation and indices of the examples and comparative examples

The properties of the polyester resins synthesized using the above-described methods of the present invention can be embodied by the properties of the resulting powder coating. The polyester resins a to D synthesized in examples 1 to 4 and the general-purpose resin E, F were prepared into powder coatings by premixing → extrusion → tabletting → preliminary crushing → grinding, respectively, according to the formulation shown in table 2. The powder coating is sprayed on an iron plate which is subjected to phosphating pretreatment in an electrostatic spraying mode, the sample plate is taken out after being solidified for 10 minutes at 200 ℃ in an oven, and after the sample plate is cooled to room temperature, various coating performances are detected, and the results are shown in table 3.

TABLE 2 formulation for preparing powder coatings for each of the examples and comparative examples

TABLE 3 comparison of mechanical properties of powder coatings prepared in examples and comparative examples

It can be seen from table 3 that the examples of the present invention have superior mechanical properties compared to general-purpose polyester resins, and the mechanical properties are still good after long-term storage, which satisfies the requirement of reprocessing of the coating after long-term storage.