CN108300181B - Stable powder slurry and preparation method and application thereof - Google Patents

Abstract

The invention provides a stable powder slurry, which is prepared from a solid-phase powder component A and a liquid-phase component B; the component A comprises polyester resin; the component B comprises water and an aqueous auxiliary agent; the component A accounts for 55-90% of the total mass of the powder slurry, and the component B accounts for 10-45% of the total mass of the powder slurry; the polyester resin in the component A is saturated or unsaturated polyester, the polyester resin accounts for 25-60% of the total mass of the component A, and the number average molecular weight of the polyester resin is 1000-10000 g/mol; the acid value of the polyester resin is 25-75 mgKOH/g; the mass ratio of the polyester resin to water is as follows: polyester resin: water ═ (0.3-12): 1. methods of making and using the powder slurry are also provided. The powder slurry of the present invention has excellent storage stability, less influence of environment temperature and capacity of being stored for over 1 year at normal temperature.

Description

Stable powder slurry and preparation method and application thereof

Technical Field

The invention belongs to the field of coating, and particularly relates to stable powder slurry, a preparation method and application of the powder slurry.

Background

The technological development of modern coating industry has focused on the research of low-pollution, environmentally friendly coatings, such as powder coatings and water-based coatings, which are now common. However, the powder coating has the problems of large investment of a coating line, difficult reduction of coating film thickness and powder pollution; aqueous coatings are hazardous because they often contain large amounts of co-solvents, and suffer from relatively low solids content and poor overall performance. As early as the 20 th century, 70-80 years, aqueous powder suspensions, also called powder slurries, were developed that combine the advantages of powder coatings with aqueous coatings, as demonstrated by: 1) the volatile carrier is water alone; 2) the by-products volatilized during the curing process are not hazardous or toxic; 3) the construction can be carried out by spraying, dipping or rolling coating equipment.

The Cray call Products and Ciba-Geigy companies that originally developed powder slurries were epoxy/polyester systems, but did not develop as rapidly because the stability of the powder slurry system was highly demanding on the epoxy variety. Recently, powder slurries of various resin systems (aqueous powder coating dispersions) have been developed and disclosed gradually: p19518392.4 discloses epoxy/polyester systems, but the weather resistance and the leveling property have certain defects; CN96198627.1 discloses an epoxy/epoxyacrylic acid system; CN200480030162.4 discloses a photo/thermal curing dual-curing system, which is a polyurethane system with a double bond structure; CN200680041867.5 discloses a multi-type resin system for photocuring; including epoxy acrylate systems, urethane acrylate systems, carbonate acrylate systems, and the like; CN104411742A discloses a polyamide resin system, which is suitable for preparing powder slurry from high molecular weight polyamide; CN102838845A discloses a water-redispersible powder of an epoxy resin system, which has good stability after dispersion; CN105061656A discloses a water redispersible powder of carboxyl terminated polyethylene based resin system. These different resin system powder slurries have respective application ranges.

With the development of powder coatings, powder coatings mainly made of carboxyl-terminated polyester resins become mainstream and are used in a plurality of application fields, and the inherent defects of the powder coatings limit the further rapid expansion of the application.

Disclosure of Invention

The invention aims to overcome the defects of high requirement, difficult thin coating and poor appearance of a coating film of the existing polyester resin-based powder coating on a coating line, and provides a polyester system water-based powder slurry, a preparation method and application of the powder slurry. Accordingly, it has been found that such powder slurries have excellent storage stability, from which products such as coatings, adhesives, sealants and the like can be prepared and are suitable for spray coating, dip coating and roll coating to give coating films of 10 to 100 μm thickness, and exhibit good leveling, hardness, mechanical properties, corrosion resistance and weather resistance.

The present invention provides a stable powder slurry prepared from a solid-phase powder component a and a liquid-phase component B;

the component A comprises polyester resin, a curing agent, a catalyst, a pigment and a filler; the component B comprises water and an aqueous auxiliary agent;

the component A accounts for 55-90% of the total mass of the powder slurry, and the component B accounts for 10-45% of the total mass of the powder slurry; the polyester resin in the component A is saturated or unsaturated polyester, the polyester resin accounts for 25-60% of the total mass of the component A, and the number average molecular weight of the polyester resin is 1000-10000 g/mol; the polyester resin has a terminal carboxyl structure or a part of the polyester resin contains a terminal double bond structure; the acid value of the polyester resin is 25-75 mgKOH/g;

the mass ratio of the polyester resin to water is as follows: polyester resin: water ═ (0.3-12): 1.

preferably, the polyester resin has a linear or branched or hyperbranched structure; the polyester resin is obtained by condensation polymerization of polybasic acid and polyhydric alcohol.

Preferably, the component A accounts for 60-85% of the total mass of the powder slurry, and the component B accounts for 15-40% of the total mass of the powder slurry.

Preferably, the curing agent accounts for 3-30% of the total mass of the component A, and the mass ratio of the curing agent, the catalyst, the pigment and the filler is as follows: curing agent: catalyst: pigment: 3-30% of filler: 0.1-1: 15-25: 15-25.

Preferably, the curing agent is one or more of a small molecule containing two or more epoxy groups or hydroxyl groups or amino groups, an epoxy resin and an amino resin.

Preferably, the catalyst is one or more of 2-phenylimidazole, dodecyl tertiary amine, triphenyl phosphorus, triphenyl ethyl phosphorus bromide, triphenyl ethyl phosphorus chloride, tribenzyl ethyl phosphorus bromide and tribenzyl ethyl phosphorus chloride.

Preferably, the pigment is one or more of inorganic pigment, organic pigment, fluorescent pigment, metallic pigment and pearlescent pigment.

Preferably, the pigment is one or more of azo pigments, anthraquinone pigments, benzimidazole pigments, dihydroquinacridone pigments, quinophthalone pigments, diketopyrrolopyrrole pigments, isoindoline pigments, isoindolinone pigments, metal complex pigments, perylene pigments, phthalocyanine pigments, aniline black, titanium dioxide, zinc white, carbon black, iron manganese black, chromate pigments (e.g., chromium oxide hydrate), iron oxide brown, iron oxide yellow or bismuth vanadate. These pigments may be used alone or in the form of a mixture.

Preferably, the filler is one or more of diatomite, talcum powder, calcium carbonate, kaolin, barium sulfate, magnesium silicate, crystalline silica, amorphous silica and alumina.

All the assistants in the component B are conventional water-based assistants, and are flexibly selected according to the preparation process.

Preferably, the aqueous auxiliary agent comprises water, a wetting dispersant, a leveling agent, a defoaming agent, a thickening agent, an antioxidant and an ultraviolet absorbent.

The present invention also provides a method for preparing a powder slurry according to the above, comprising the steps of:

(1) fully mixing the polyester resin, the curing agent, the catalyst, the pigment and the filler in the component A, then performing melt extrusion at the temperature of 80-110 ℃ through an extruder, cooling, crushing and sieving to obtain powder particles, wherein the particle size of the powder particles is 5-55 mu m;

(2) fully mixing the powder particles obtained in the step (1) with the component B, and then carrying out wet grinding, wherein the grinding equipment is a sand grinding agent or a ball mill, and the grinding temperature is 40-60 ℃;

(3) and (3) adjusting the mixture obtained in the step (2) by using amines or ammonia to reach the pH value of 5-9, thus obtaining stable powder slurry.

Preferably, the amine is one or more of ethylenediamine, hexamethylenediamine, triethanolamine and triethylamine, and the ammonia is ammonia water.

The invention also provides the use of a powder slurry according to the above for the preparation of coatings, adhesives, sealants or for the preparation of coating films having a thickness of 10 to 100 μm.

The invention has the beneficial effects that:

the powder slurry of the present invention has excellent storage stability, less influence of environment temperature and capacity of being stored for over 1 year at normal temperature.

The powder slurry of the present invention has the following application modes: the powder slurry can be coated by a method known in the liquid coating technology, and can be coated by a spraying technology, a rolling coating method and a dip coating method; the coated powder slurry was pre-dried at 40-70 ℃ for 5-15 minutes and then baked to dryness at 120-180 ℃.

Detailed Description

The following further illustrates embodiments of the invention:

examples 1-3 preparation of powder slurries

Examples 1-3 were prepared as follows, the components being used in the amounts shown in examples 1-3, and the powder slurry was prepared as follows:

example 1

(1) Fully mixing 15kg of polyester resin with the number average molecular weight of 4000g/mol and the acid value of 35mgKOH/g, 18kg of epoxy resin, 0.3kg of 2-phenylimidazole, 0.3kg of triphenylphosphine, 10kg of benzimidazole pigment, 5kg of isoindoline pigment, 6.4kg of diatomite and 5kg of talcum powder filler in the component A, then performing melt extrusion at the temperature of 80-110 ℃ by using an extruder, cooling, crushing and sieving to obtain powder particles with the particle size of 5-35 mu m; (2) the component B is 30kg of water, 0.5kg of wetting dispersant, 0.5kg of flatting agent, 0.5kg of defoaming agent, 0.2kg of thickening agent, 0.5kg of antioxidant and 0.3kg of ultraviolet absorbent, the powder particles obtained in the step 1 are fully mixed with the component B, and then wet grinding is carried out, wherein grinding equipment can be a sand grinding agent and a ball mill, and the grinding temperature is 40-60 ℃; (3) and (3) adjusting the mixture obtained in the step (2) by using ethylenediamine to reach the pH value of 7, thus obtaining stable powder slurry.

Example 2

(1) 51kg of polyester resin with the number average molecular weight of 3500g/mol and the acid value of 60mgKOH/g, 7.65kg of amino resin, 0.4kg of tribenzyl ethyl phosphorus bromide, 0.45kg of triphenyl ethyl phosphorus chloride, 7.75kg of iron oxide brown, 5kg of iron oxide yellow, 3.75kg of kaolin, 5kg of talcum powder and 3kg of magnesium silicate filler are fully mixed, melted and extruded at the temperature of 80-110 ℃ by an extruder, cooled, crushed and sieved to obtain powder particles with the particle size of 20-40 mu m; (2) the component B is 10kg of water, 0.6kg of wetting dispersant, 0.8kg of flatting agent, 0.5kg of defoaming agent, 0.1kg of thickening agent, 0.3kg of antioxidant and 0.5kg of ultraviolet absorbent, the powder particles obtained in the step 1 are fully mixed with the component B, and then wet grinding is carried out, wherein grinding equipment can be a sand grinding agent and a ball mill, and the grinding temperature is 40-60 ℃; (3) and (3) regulating the mixture obtained in the step (2) by using triethanolamine to reach the pH value of 6.5, thus obtaining stable powder slurry.

Example 3

(1) 24.5kg of the component A with the number average molecular weight of 9000g/mol and the acid value of 75mgKOH/g of polyester resin, 8.25kg of propylene glycol, 0.15kg of dodecyl tertiary amine, 0.1kg of tribenzyl ethyl phosphorus chloride, 6kg of aniline black, 5kg of iron manganese black, 6kg of amorphous silica and 5kg of crystalline silica filler are fully mixed, melted and extruded at the temperature of 80-110 ℃ by an extruder, and after cooling, the mixture is crushed, crushed and sieved to obtain powder particles with the particle size of 25-55 mu m; (2) the component B is 40kg of water, 0.5kg of wetting dispersant, 0.5kg of flatting agent, 0.1kg of defoaming agent, 0.7kg of thickening agent, 0.3kg of antioxidant and 0.5kg of ultraviolet absorbent, the powder particles obtained in the step 1 are fully mixed with the component B, and then wet grinding is carried out, wherein grinding equipment can be a sand grinding agent and a ball mill, and the grinding temperature is 40-60 ℃; (3) and (3) adjusting the mixture obtained in the step (2) by using triethylamine to reach the pH value of 8.5, thus obtaining stable powder slurry.

Comparative examples 1-3 preparation of comparative powder slurry

Comparative example 1: comparative example 1 except for example 1 that the number average molecular weight of the polyester resin in component A was 20000g/mol, and other conditions were the same as in example 1, powder slurry A1 was prepared.

Comparative example 2: comparative example 2 differs from example 3 in that the acid value of the polyester resin in component A was 120mgKOH/g, and powder slurry A2 was prepared under the same conditions as in example 1.

Comparative example 3: comparative example 3 differs from example 3 in that powder slurry A3 was prepared by crushing, pulverizing, and sieving in step (1) to obtain powder particles having an average particle size of greater than 60 μm and 50% of the powder particles having an average particle size of greater than 100 μm, under otherwise unchanged conditions.

Comparative example 4: comparative example 4 except for using 300kg of water in component B and the same conditions as in example 1, powder slurry A4 was prepared in example 1.

Effects of the embodiment

The powder slurries prepared in examples 1 to 3 and comparative examples 1 to 3 were put in a colorimetric cylinder in equal amounts, stored for 6 months at a prohibition condition at normal temperature, and the sedimentation height and coagulation condition of the 6 kinds of powder slurries were measured; and temperature influence detection, namely, placing the powder slurry at 25 ℃ for one week, placing the powder slurry at 38 ℃ for one week, and observing whether the powder slurry is coagulated (whether the powder slurry is coagulated at 25-38 ℃ in the table 1), wherein the specific effects are shown in the table 1:

TABLE 1

As can be seen from the data results in Table 1, the powder slurry prepared by using the polyester resin with larger number average molecular weight in the component A in the comparative example 1 is easy to settle and agglomerate, and the performance is unstable because the polyester resin with larger number average molecular weight has poor dispersion stability, larger relative density and easy agglomeration; when the powder particles are screened in comparative example 3, if the particle size is too large, the powder particles are easy to settle in a dispersion system, and the stabilizing effect is poor; in comparative example 4, an excessive amount of water was added, and the excessive amount of water caused hydrolysis of the polyester resin, lowering the dispersing ability of the polyester resin, and deteriorating the stabilizing effect. In the experiment, the product and the method of the invention are obtained by exploring the polyester resin and the preparation method, and the stable powder slurry of the invention is obtained by combining the selected polyester resin and the method condition; and the powder slurry products of examples 1-3 were less affected by temperature changes, whereas the powder slurries of comparative examples 1-3 appeared to agglomerate and be unstable after ambient temperature changes.

Application examples

The powder slurries prepared in examples 1 to 3 and comparative examples 1 to 4 were used as coating materials, the coating materials of examples 1 to 2 and comparative examples 1 to 3 were applied to a substrate by roll coating, the coating materials of example 3 and comparative example 4 were applied to a substrate by air pressure spraying, whether leveling and curing were carried out or not was checked in a 15min oven tunnel at 200 ℃ and 180 ℃, the thickness of the coating film, the hardness of the coating film, and the width of single-sided corrosion resistance against salt spray for 100h, and the specific data are shown in Table 2:

TABLE 2

Example 1

Example 2

Example 3

Comparative example 1

Comparative example 2

Comparative example 3

Comparative example 4

Coating thickness of mu m

90

70

20

80

90

70

10

Levelling

Good effect

Good effect

Good effect

Is poor

Is poor

Is poor

Is poor

Whether it can be cured within 3min

Can be used for

Can be used for

Can be used for

Can be used for

Can not

Can be used for

Can be used for

Hardness H

＞1

＞1

＞1

＞1

＜1

＞1

＞1

Corrosion on one side cm

＜3

＜3

＜3

＞5

＞20

＞5

＞15

As can be seen from the data results in Table 2, the performances of the coatings prepared in examples 1 to 3 are better than those of the coatings prepared in comparative examples 1 to 4, and the coatings have good leveling property, hardness and corrosion resistance, the acid value of the polyester resin in comparative example 2 is higher and the polyester resin is easy to hydrolyze, the water content in comparative example 4 is too high, the coatings are easy to corrode due to the comparative examples 2 and 4, and as a result, the unilateral corrosion is serious; it can be seen that the powder slurries of the present invention are more stable and the coatings used in the preparation are also more stable.

Variations and modifications to the above-described embodiments may occur to those skilled in the art, which fall within the scope and spirit of the above description. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and some modifications and variations of the present invention should fall within the scope of the claims of the present invention. Furthermore, although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims (7)

1. A stable powder slurry, wherein said powder slurry is prepared from a solid phase powder component a and a liquid phase component B;

the component A comprises polyester resin, a curing agent, a catalyst, a pigment and a filler; the component B comprises water and an aqueous auxiliary agent;

the component A accounts for 60-85% of the total mass of the powder slurry, and the component B accounts for 15-40% of the total mass of the powder slurry; the polyester resin in the component A is saturated or unsaturated polyester, the polyester resin accounts for 25-60% of the total mass of the component A, and the number average molecular weight of the polyester resin is 1000-10000 g/mol; the polyester resin has a terminal carboxyl structure or a part of the polyester resin contains a terminal double bond structure; the acid value of the polyester resin is 25-75 mgKOH/g;

the mass ratio of the polyester resin to water is as follows: polyester resin: water ═ (0.3-12): 1;

the polyester resin has a linear or branched or hyperbranched structure; the polyester resin is obtained by condensation polymerization of polybasic acid and polyhydric alcohol;

the curing agent accounts for 3-30% of the total mass of the component A, and the mass ratio of the curing agent to the catalyst to the pigment to the filler is as follows: curing agent: catalyst: pigment: 3-30% of filler: 0.1-1: 15-25: 15-25.

2. The powder slurry of claim 1, wherein the curing agent is one or more of a small molecule containing two or more epoxy groups or hydroxyl groups or amino groups, an epoxy resin, and an amino resin.

3. The powder slurry of claim 1, wherein the catalyst is one or more of 2-phenylimidazole, dodecyltertiary amine, triphenylphosphine, triphenylethylphosphonium bromide, triphenylethylphosphonium chloride, tribenzylethylphosphonium bromide, and tribenzylethylphosphonium chloride.

4. The powder slurry of claim 1, wherein the pigment is one or more of an inorganic pigment, an organic pigment, a fluorescent pigment, a metallic pigment, a pearlescent pigment.

5. The powder slurry of claim 1, wherein the filler is one or more of diatomaceous earth, talc, calcium carbonate, kaolin, barium sulfate, magnesium silicate, crystalline silica, amorphous silica, alumina.

6. The method for preparing a powder slurry according to any one of claims 1 to 5, wherein the method comprises the steps of:

(1) fully mixing the polyester resin, the curing agent, the catalyst, the pigment and the filler in the component A, then performing melt extrusion at the temperature of 80-110 ℃ through an extruder, cooling, crushing and sieving to obtain powder particles, wherein the particle size of the powder particles is 5-55 mu m;

(2) fully mixing the powder particles obtained in the step (1) with the component B, and then carrying out wet grinding, wherein the grinding equipment is a sand grinding agent or a ball mill, and the grinding temperature is 40-60 ℃;

(3) and (3) adjusting the mixture obtained in the step (2) by using amines or ammonia to reach the pH value of 5-9, thus obtaining stable powder slurry.

7. Use of the powder slurry according to any one of claims 1 to 5 for the preparation of coatings, adhesives, sealants or for the preparation of coating films having a thickness of 10 to 100 μm.