CN113527981B - Thin-coating high-humidity-resistant heat-insulating powder and preparation method thereof - Google Patents

Abstract

The invention discloses a thin-coating high-humidity heat-resistant insulating powder and a preparation method thereof, wherein the thin-coating high-humidity heat-resistant insulating powder comprises the following raw materials in parts by weight: resin A: 20% -30%, resin B: 20% -25%, curing agent: 10% -20%, flame-retardant filler: 22% -40%, various auxiliary agents: 1 to 3 percent, and the total weight of the components is 100 percent. The thin coating high-humidity heat-resistant insulating powder overcomes the defects that solid powder coating has poor leveling and cannot realize a complete high-quality protective coating by thin coating, has excellent electrical insulation and high flame retardance, can resist the invasion of acid, alkali and corrosive environments, and can completely meet the mechanical performance requirements of common impact and winding.

Description

Thin-coating high-humidity-resistant heat-insulating powder and preparation method thereof

Technical Field

The invention relates to a thin-coating high-humidity-resistant heat-insulating powder and a preparation method thereof, belonging to the field of new materials.

Background

A connecting bar for a new energy automobile battery pack and a connecting bar for a photovoltaic solar panel are raised and developed rapidly in recent years, an insulating layer of the connecting bar is insulated by a thermoplastic sleeve according to a connecting bar of a traditional high-voltage electric cabinet, the thermoplastic sleeve is short in service life and low in voltage resistance and suffers from scaling, and the connecting bar is comprehensively coated with insulating powder along with the occurrence of spontaneous combustion accidents of some battery packs. The insulating powder coating also has the disadvantages of being limited by the volume compression of the battery pack and very limited placing space, so the thickness of the insulating layer on the connecting bar is usually limited to be less than 0.3mm, the working environment is in a high-temperature and high-humidity state for a long time, and simultaneously, the risk of instantaneous high-voltage breakdown is also faced, and the requirement on the insulating layer is very strict.

The existing insulating powder is basically the traditional epoxy insulating powder, the phenomena of pulverization and shedding can occur in a high-temperature environment, the insulativity of a high-humidity environment is obviously reduced, high voltage-resistant grade can not be realized by thin coating, and the application of powder coating on a connecting bar is limited due to the common defects. Therefore, the preparation of the insulating powder coating which can simultaneously meet the requirements of high temperature, high humidity and high voltage resistance of a thin coating is of great significance.

Disclosure of Invention

The invention aims to provide a thin-coating high-humidity-heat-resistant insulating powder, which is designed for insulating coating of a connecting bar for a new energy automobile battery pack and a connecting bar for a photovoltaic solar panel, aims at a series of defects of thermoplastic sleeves, ensures that the designed insulating powder is vulcanized to be more suitable for insulating coating of non-standard connecting bars and fastening hole positions, has outstanding voltage-resistant grade, flame-retardant property and various mechanical properties, is greatly higher than the properties of the traditional insulating powder, can meet all standard requirements of the connecting bar when the thickness of the coating is about 0.2mm, can greatly compress the volume of the battery pack due to the small volume brought by the thin coating, and has important significance for the development trend of light weight and miniaturization of the battery pack.

Another object of the present invention is to provide a method for preparing a thin-coated high humidity heat resistant insulating powder.

In order to solve the technical problems, the technical scheme adopted by the invention is as follows:

a thin-coating high-humidity-resistant heat-insulating powder comprises the following raw materials in parts by weight:

resin A: 20% -30%;

resin B: 20% -25%;

curing agent: 10% -20%;

flame-retardant filler: 22% -40%;

auxiliary agent: 1% -3%; the sum of the weight of the components is 100 percent.

Preferably, the resin A is hyperbranched polyurethane modified epoxy resin, the resin is hyperbranched polyurethane polymer modified bisphenol S epoxy resin, and the curing crosslinking density can be greatly increased by utilizing high-density end group functional groups in the molecular structure of the resin, so that various mechanical properties of the coating are increased. The preparation method comprises the following steps: putting solid bisphenol S epoxy resin with the epoxy equivalent of 450-500 g/eq into an open mill, opening at 80 ℃, adding hyperbranched polyurethane (the mass ratio of the hyperbranched polyurethane to the epoxy resin is 1: 2-1: 3) in a completely molten state, opening at 120 ℃ for 20min, setting the rotating speed of the open mill at 30r/min, tabletting while hot, cooling and crushing to obtain the hyperbranched polyurethane modified epoxy resin.

Preferably, the resin B is a nano boron oxide modified epoxy resin, the resin is an epoxy resin reinforced by inorganic nano boron oxide particles, so that the mechanical property, the breaking strength, the surface hardness and other properties of the resin are improved, and the hydroxylated and silane-surfaced nano boron oxide can be freely integrated with the epoxy resin. The preparation method comprises the following steps: carrying out surface treatment on the hydroxylated nano boron oxide silane, placing solid bisphenol A epoxy resin with the epoxy equivalent of 600-640 g/eq into an internal mixer for internal mixing at 90 ℃ for 5min, adding the treated nano boron oxide at 100 ℃, continuing the internal mixing for 20min, tabletting while hot, cooling and crushing to obtain the nano boron oxide modified epoxy resin.

Preferably, the curing agent is a benzophenone-tetrahydrodianhydride and isophthalic acid hydrazide composite system, and the mass ratio is 1: 1.

Preferably, the flame-retardant filler is a mixture of a compound flame retardant and sepiolite. The compound flame retardant is a mixture of phosphazene and MCA, the mass ratio of the phosphazene to the MCA is 1:1, and the mass sum of the phosphazene and the MCA accounts for 10-15% of the total mass of the flame retardant filler. The particle size of the sepiolite micro powder is between 1000 and 5000 meshes.

Preferably, the auxiliary agent is a mixture of an accelerator, a leveling agent, an antioxidant, a defoaming agent and a pigment.

The supported type accelerant is characterized in that the violent reaction temperature is 150-180 ℃, the activation temperature is high in beginning, the range is narrow, the supported type accelerant can be instantly cured in the expected temperature range, the supported type accelerant is matched with the same high activation temperature of a curing system to prevent a coating from being gelatinized in advance to influence the leveling, and the combination is the key for realizing the good leveling appearance of a thin coating.

The invention also discloses a preparation method of the insulating powder, which adopts the following steps that are connected in sequence:

(1) putting solid bisphenol S epoxy resin into an open mill for open refining at 80 ℃, adding hyperbranched polyurethane (the mass ratio of the hyperbranched polyurethane to the epoxy resin is 1: 2-1: 3) in a completely molten state, open refining at 120 ℃ for 20min, keeping the rotating speed of the open mill at 30r/min, tabletting when the mixture is hot, cooling and crushing to obtain hyperbranched polyurethane modified epoxy resin;

(2) placing hydroxylated nano boron oxide in a container, adding a toluene solution, carrying out ultrasonic treatment for 30min, then adding a silane coupling agent, carrying out magnetic stirring for 24h at 80 ℃, washing for 3 times, filtering, carrying out vacuum drying for 12h at 80 ℃ for standby use, placing solid bisphenol A epoxy resin in an internal mixer for internal mixing for 5min at 90 ℃, adding the treated nano boron oxide at 100 ℃, continuing internal mixing for 20min, carrying out tabletting while hot, cooling and crushing to obtain nano boron oxide modified epoxy resin;

(3) putting the fragments obtained in the steps (1) and (2) into a mixing tank, adding a corresponding part of curing agent, and stirring for 5min at a speed of 800-900 r/min; then adding the flame-retardant filler and the auxiliary agent, and continuously stirring for 10min at the speed of 800-900 r/min to fully and uniformly mix;

(4) melting and extruding the mixture in the step (3) through a double screw, wherein the temperature of a melting section is 90-100 ℃, the extrusion temperature of a machine head is 100-; tabletting by a tabletting machine, air cooling, crushing, air grading grinding granulation and sieving to obtain finished powder.

The technical scheme adopted by the invention has the beneficial effects that:

the invention discloses a thin coating high-humidity heat-resistant insulating powder which is innovative in that two novel modified epoxy resins are used, and a high-activation-temperature composite curing system and a high-activation-temperature accelerator are matched, so that a thin coating layer obtains a good leveling appearance. The modification of the high-density branched end group greatly improves the crosslinking density in the coating curing process, and various performances are improved qualitatively. The modification of the inorganic nanoparticles can comprehensively improve the toughness, strength, curing shrinkage and the like of the coating, and the improvement of the performances can realize that the thin coating reaches or even exceeds the standard of the technical field. In addition, the thin coating has great significance for saving cost and reducing energy consumption, and the performance of high temperature and high humidity resistance (the temperature is about 85 ℃, the relative humidity is about 93 percent, the change rate of mechanical properties is less than or equal to 10 percent and the damage condition of a paint film is better than the first level) is necessary in a plurality of high-precision fields, so that the brand-new application field of the insulating powder can be developed; in addition, the preparation method of the thin-coating high-humidity heat-resistant insulating powder is simple, and the product is stable, so that the thin-coating high-humidity heat-resistant insulating powder is an ideal insulating material in the field of new energy batteries.

Detailed Description

For a further understanding of the present invention, reference will now be made to specific examples, which are not intended to be limiting.

In the invention, the auxiliary agent is a mixture of an accelerator, a leveling agent, an antioxidant, a defoaming agent and a pigment. Wherein, the available accelerant selects phosphotungstic acid loaded 2-phenyl-4, 5-dimethylol imidazole or phosphotungstic acid loaded 4-methyl imidazole. Leveling agents, antioxidants, defoamers, and pigments are furthermore conventional choices in the art.

The filler selected by the invention is sepiolite micro powder, the mesh number is 1000-5000 meshes, the preferred mesh number is 2000 meshes, and the other suitable mesh numbers (such as 1000 meshes, 3000 meshes, 4000 meshes and 5000 meshes) all fall into the protection scope of the invention.

Example 1

A thin-coating high-humidity-resistant heat-insulating powder comprises the following raw materials in parts by weight:

resin A20%, resin B20%, curing agent 17%, flame-retardant filler 40% (wherein the mass of the compound flame retardant accounts for 15% of the mass of the flame-retardant filler), and auxiliary agent 3% (wherein the mass of the flame-retardant filler contains accelerator 0.45%).

The resin A is hyperbranched polyurethane modified bisphenol S epoxy resin, and the epoxy equivalent range is 450-500 g/eq.

The resin B is nano boron oxide modified epoxy resin, and the epoxy equivalent is 600-640 g/eq.

The curing agent is a benzophenone-tetrahydrodianhydride and isophthalic acid hydrazide composite system with the mass ratio of 1: 1.

Example 2

A process for preparing a thin-coated high-humidity-resistant heat-insulating powder, the amounts of the raw material components of which are as described in example 1, comprises the following steps in succession:

(1) putting solid bisphenol S epoxy resin into an open mill for open refining at 80 ℃, adding hyperbranched polyurethane (the mass ratio of the hyperbranched polyurethane to the epoxy resin is 1: 2) in a completely molten state, open refining at 120 ℃ for 20min at the rotating speed of the open mill of 30r/min, tabletting while hot, cooling and crushing for later use;

(2) placing hydroxylated nano boron oxide in a container, adding a toluene solution, carrying out ultrasonic treatment for 30min, then adding gamma-aminopropyltriethoxysilane, carrying out magnetic stirring for 24h at 80 ℃, washing for 3 times, filtering, carrying out vacuum drying for 12h at 80 ℃ for standby use, placing solid bisphenol A epoxy resin in an internal mixer for internal mixing for 5min at 90 ℃, adding the treated nano boron oxide and carrying out internal mixing for 20min at 100 ℃, tabletting while hot, cooling and crushing for standby use;

(3) putting the fragments obtained in the steps (1) and (2) into a mixing tank, then adding corresponding parts of benzophenonetetrahydro dianhydride and isophthalic acid hydrazide, and stirring at 800r/min for 5 min; then adding the phosphazene, MCA, sepiolite and the auxiliary agent, and continuing stirring at 800r/min for 10min to fully and uniformly mix;

(4) melting and extruding the mixture in the step (3) through a double screw, wherein the temperature of a melting section is 90-100 ℃, the extrusion temperature of a machine head is 100-; tabletting by a tabletting machine, air cooling, crushing, air grading grinding granulation and sieving to obtain finished powder.

After testing, the indexes are listed in Table 1.

Example 3

The thin-coating high-humidity-resistant heat-insulating powder comprises, by weight, resin A30%, resin B25%, a curing agent 20%, a flame-retardant filler 22% (wherein the mass of a compound flame retardant accounts for 10% of the mass of the flame-retardant filler), and an auxiliary agent 3% (wherein the mass of the auxiliary agent contains 0.2% of an accelerator).

Wherein the selection of the resin A, the resin B and the curing agent is the same as the example 1, and the preparation method is the same as the example 2.

After testing, the indexes are listed in Table 1.

Example 4

The thin-coating high-humidity-resistant heat-insulating powder comprises, by weight, resin A25%, resin B25%, a curing agent 10%, a flame-retardant filler 39% (wherein the mass of a compound flame retardant accounts for 15% of the mass of the flame-retardant filler), and an auxiliary agent 1% (wherein the mass of the auxiliary agent contains an accelerator 0.4%).

Wherein the selection of the resin A, the resin B and the curing agent is the same as the example 1, and the preparation method is the same as the example 2.

After testing, the indexes are listed in Table 1.

Comparative example 1

The same raw material selection as in example 1 was used except that the conventional bisphenol a type solid epoxy resin was used as the resin a and the resin B. The weight parts of the raw materials are 30% of resin A (epoxy equivalent: 450-500 g/eq), 20% of resin B (epoxy equivalent: 600-640 g/eq), 10% of curing agent, 38% of flame-retardant filler (wherein the mass of the compound flame retardant accounts for 15% of the total filler mass), and 2% of auxiliary agent (wherein the mass of the auxiliary agent contains 0.4% of accelerator).

The preparation method is the same as example 2.

After testing, the indexes are listed in Table 1.

Comparative example 2

The same raw material selection was used as in example 1, except that the filler component was replaced with calcium carbonate. The components of the raw materials in parts by weight are resin A20%, resin B20%, curing agent 17%, flame-retardant filler 40% (wherein the mass of the compound flame retardant accounts for 10% of the mass of the flame-retardant filler), and assistant 3% (wherein the mass of the assistant comprises 0.4%).

The preparation method is the same as example 2.

After testing, the indexes are listed in Table 1.

Comparative example 3

The same raw material selection as in example 1 was used, except that the curing system was changed to a conventional phenolic curing agent. The components of the raw materials in parts by weight are resin A30%, resin B25%, curing agent 15%, flame-retardant filler 28% (wherein the mass of the compound flame retardant accounts for 15% of the mass of the flame-retardant filler), and auxiliary agent 2% (wherein the mass of the auxiliary agent contains accelerator 0.4%).

The preparation method is the same as example 1.

After testing, the indexes are listed in Table 1.

Comparative example 4

The same raw material selection as in example 1 was used, except that the accelerator was replaced with a conventional imidazole accelerator. The components of the raw materials in parts by weight are resin A30%, resin B20%, curing agent 15%, flame-retardant filler 33% (wherein the mass of the compound flame retardant accounts for 15% of the mass of the flame-retardant filler), and auxiliary agent 2% (wherein the mass of the auxiliary agent contains accelerator 0.4%).

The preparation method is the same as example 1.

After testing, the indexes are listed in Table 1.

TABLE 1

As can be seen from Table 1 above, in examples 2-4, the preparation method according to the present invention is only changed by the ratio of the components, and the powder coating has excellent performance as a whole, especially the moisture-heat resistance and voltage resistance have only very small differences, which far exceed the requirements of the industry standard; comparative examples 1 to 4 were each modified by the following method using a controlled variable: the modified resin is replaced by the traditional epoxy resin, the sepiolite is replaced by calcium carbonate, the compound curing system is replaced by the traditional phenol curing agent, the supported accelerant is replaced by the traditional imidazole accelerant, no matter one or more components are changed, the influence on the overall performance of the powder coating is large, and the humidity and heat resistance and the voltage resistance are reduced remarkably.

In light of the foregoing description of the preferred embodiment of the present invention, many modifications and variations will be apparent to those skilled in the art without departing from the spirit and scope of the invention. The technical scope of the present invention is not limited to the contents of the specification.

Claims (5)

1. A thin-coating high-humidity-resistant heat-insulating powder is characterized by comprising the following raw materials in parts by weight:

resin A: 20% -30%;

resin B: 20% -25%;

curing agent: 10% -20%;

flame-retardant filler: 22% -40%;

auxiliary agent: 1% -3%; the total weight of the components is 100 percent;

the resin A is hyperbranched polyurethane modified epoxy resin;

the resin B is nano boron oxide modified epoxy resin;

the curing agent is a benzophenone tetrahydrodianhydride and isophthalic acid hydrazide composite system with the mass ratio of 1: 1;

the auxiliary agent comprises an accelerant, and the accelerant is 4, 5-dihydroxymethyl-2-phenylimidazole loaded with phosphotungstic acid or 4-methylimidazole loaded with phosphotungstic acid;

the flame-retardant filler is a mixture of a compound flame retardant and sepiolite.

2. The thinly coated high humidity resistant thermal insulating powder according to claim 1, wherein: the preparation method of the resin A comprises the following steps: putting solid bisphenol S epoxy resin with the epoxy equivalent of 450-500 g/eq into an open mill, boiling off at 80 ℃, adding hyperbranched polyurethane in a completely molten state, boiling off at 120 ℃ for 20min at the rotating speed of the open mill of 30r/min according to the mass ratio of the hyperbranched polyurethane to the epoxy resin of 1: 2-1: 3, tabletting while hot, cooling and crushing to obtain the hyperbranched polyurethane modified epoxy resin.

3. The thinly coated high humidity resistant thermal insulating powder according to claim 1, wherein: the preparation method of the resin B comprises the following steps: carrying out surface treatment on the hydroxylated nano boron oxide silane, placing solid bisphenol A epoxy resin with the epoxy equivalent of 600-640 g/eq into an internal mixer for internal mixing at 90 ℃ for 5min, adding the treated nano boron oxide at 100 ℃, continuing the internal mixing for 20min, tabletting while hot, cooling and crushing to obtain the nano boron oxide modified epoxy resin.

4. The thinly coated high humidity resistant thermal insulating powder according to claim 1, wherein: the auxiliary agent is a mixture of a compatilizer, an accelerator, a leveling agent, an antioxidant, a defoaming agent and a pigment.

5. A method of preparing an insulating powder according to any one of claims 1 to 4, characterized in that: the method comprises the following steps of:

(1) putting solid bisphenol S epoxy resin into an open mill for open refining at 80 ℃, adding hyperbranched polyurethane in a completely molten state, opening the solid bisphenol S epoxy resin for 20min at 120 ℃ at the mass ratio of the hyperbranched polyurethane to the epoxy resin of 1: 2-1: 3, tabletting the mixture while the mixture is hot, and cooling and crushing the mixture to obtain hyperbranched polyurethane modified epoxy resin;

(2) placing hydroxylated nano boron oxide in a container, adding a toluene solution, carrying out ultrasonic treatment for 30min, then adding a silane coupling agent, carrying out magnetic stirring for 24h at 80 ℃, washing for 3 times, filtering, carrying out vacuum drying for 12h at 80 ℃ for standby use, placing solid bisphenol A epoxy resin in an internal mixer for internal mixing for 5min at 90 ℃, adding the treated nano boron oxide at 100 ℃, continuing internal mixing for 20min, carrying out tabletting while hot, cooling and crushing to obtain nano boron oxide modified epoxy resin;

(3) putting the fragments obtained in the steps (1) and (2) into a mixing tank, adding a corresponding part of curing agent, and stirring for 5min at a speed of 800-900 r/min; then adding the flame-retardant filler and the auxiliary agent, and continuously stirring for 10min at the speed of 800-900 r/min to fully and uniformly mix;

(4) melting and extruding the mixture in the step (3) through a double screw, wherein the temperature of a melting section is 90-100 ℃, the extrusion temperature of a machine head is 100-; tabletting by a tabletting machine, air cooling, crushing, air grading grinding granulation and sieving to obtain finished powder.