CN118546599A - Environment-friendly single-component high-temperature baking intermediate paint as well as preparation method and application thereof - Google Patents

Abstract

The invention discloses an environment-friendly single-component high-temperature baking intermediate coat, which comprises the following components in parts by weight: 22-28 parts of hydroxy acrylic resin, 1.5-2 parts of dispersing agent, 8-10 parts of pigment, 30-35 parts of filler, 8-15 parts of cross-linking agent, 2-4 parts of matting agent and 10-20 parts of organic solvent; wherein the solid content of the hydroxy acrylic resin is 59-65%, the hydroxyl value is 25-40mgKOH/g, the acid value is 3-8mgKOH/g, and the Tg is 45+ -5 ℃. The middle paint has low construction VOC, high normal temperature drying speed, good sanding property and adhesive force, has no adverse effect on the appearance and decoration of matched finish paint, and meets the requirements of users. The invention also discloses a preparation method and application of the intermediate paint.

Description

Environment-friendly single-component high-temperature baking intermediate paint as well as preparation method and application thereof

Technical Field

The invention relates to the technical field of middle coating. More particularly relates to an environment-friendly single-component high-temperature baking intermediate coat and a preparation method and application thereof.

Background

In recent years, with the development of domestic economy, the requirements of the nation on environmental protection are also higher, and the requirements of enterprises for environment-friendly coatings with lower construction VOC are also more urgent. In the application field of general industrial paint, whether agricultural machine paint or heavy machine paint, an application client is required to provide environment-friendly paint conforming to GB 30981 or GB/T38597 on the premise of not reducing the tolerance and aesthetic requirements, so as to achieve the aim of emission reduction. In conventional agricultural machinery coating systems, which generally include an electrocoat primer, a basecoat, and a baking topcoat, the process is: polishing and repairing the electrophoresis with putty after electrophoresis, spraying and intercoating, drying at normal temperature, polishing and cleaning the part with abnormal appearance, spraying and finishing paint, baking at high temperature (140-160 ℃) and assembling at the floor. The intermediate coating is an important part, is easy to shield substrate defects, has a certain barrier effect on air and water, can prolong the corrosion resistance of a matched system, and meanwhile, the good intermediate coating needs to have high sanding property and is helpful for improving the appearance and decoration of a finish paint coating.

In the field of agricultural or light machinery, there are two types of conventional approaches to centring in paint manufacturing. One is a single-component coating made by matching macromolecule, high Tg and epoxy or acrylic resin with the solid content below 50% with easily polished filler; the other is a two-component coating made by using hydroxy acrylic resin and isocyanate curing agent.

In the first mode, the resulting intermediate coating generally comprises macromolecules, high Tg, epoxy or acrylic resins having less than 50% solids, pigment and filler, and a substantial amount of solvent. The Tg of the resin is very high, so that the resin can achieve quick drying and good polishing performance, but the viscosity of the resin also increases rapidly along with the increase of the molecular weight of the resin, so that the solid content of the resin coated in the coating production cannot be too high, the coating consumption tax (VOC is more than 420 g/L) is required to be paid in the production, and a large amount of diluent is required to be added to reduce the viscosity during site construction, so that the construction VOC is seriously out of standard and unacceptable to customers.

In the second mode, the acrylic resin containing hydroxyl reactive groups is generally adopted as the grinding resin to prepare the component A containing pigment and filler and solvent, and then the component B containing NCO reactive groups is matched and mixed in proportion before construction, so that the operation can effectively reduce the construction VOC of the product, the drying property and the grindability of the product can be improved by adding the drier, but the two-component product has troublesome operation, strict proportioning requirements, the prepared paint has short usable time, the on-site water flowing property is not easy to operate, and the adhesion problem is easily caused by the subsequent baking of the two-component paint matched with the high-temperature finish paint, so that the two-component paint is rarely used on site.

Disclosure of Invention

Based on the problems, the invention aims to provide a low-VOC environment-friendly single-component high-temperature baking intermediate coating as well as a preparation method and application thereof. The middle paint can be used in the field of agricultural machinery, the defects are well solved on the premise of not changing the condition of a middle paint construction assembly line, the low construction VOC, the rapid normal-temperature drying speed, the good polishing property and the adhesive force of the middle paint construction are ensured, meanwhile, the appearance and the decoration of the matched finish paint are not adversely affected, and the requirements of users are met.

On the one hand, the invention provides an environment-friendly single-component high-temperature baking intermediate paint, which comprises the following components in parts by weight:

22-28 parts of hydroxy acrylic resin, 1.5-2 parts of dispersing agent, 8-10 parts of pigment, 30-35 parts of filler, 8-15 parts of cross-linking agent, 2-4 parts of matting agent and 10-20 parts of organic solvent;

Wherein the solid content of the hydroxy acrylic resin is 59-65%, the hydroxyl value is 25-40mgKOH/g, the acid value is 3-8mgKOH/g, and the Tg is 45+ -5 ℃.

Further, the dispersant is selected from polyester copolymers containing acidic groups.

Further, the pigment is selected from one or more of titanium dioxide and carbon black.

Further, the filler is selected from precipitated barium sulfate.

Further, the hydroxy acrylic resin is selected from one or more of FS-2060A of the courtesy, ACRYDIC BU-955 of the diease or ACS-1063VARNISH of the Libang.

Further, the crosslinking agent is selected from the group consisting of a mixture of blocked isocyanate and epoxy crosslinking agent; wherein the mass ratio of the blocked isocyanate to the epoxy resin cross-linking agent is 0.375-0.5:1.

Further, the epoxy resin crosslinking agent is selected from E-20 epoxy resins.

Further, the raw materials of the middle paint comprise the following components in parts by weight:

25 parts of hydroxy acrylic resin, 1.5-1.7 parts of dispersing agent, 8-10 parts of pigment, 30-35 parts of filler, 11.5 parts of cross-linking agent, 2-4 parts of matting agent and 10-20 parts of organic solvent.

Further, the raw materials of the middle coating paint also comprise 0.2-0.3 part of anti-settling agent and 0.02-0.06 part of leveling agent.

In yet another aspect, the present invention provides a method for preparing the environmental-friendly one-component high-temperature baking mid-coat paint as described above, the method comprising the steps of:

Mixing part of the organic solvent, the hydroxy acrylic resin and the dispersing agent;

Optionally, adding an anti-settling agent under stirring, and continuing stirring for 5-10 minutes;

adding pigment and filler under stirring, and continuously stirring and mixing;

Adding the rest organic solvent under the stirring condition, and continuously stirring until the mixture is uniformly mixed;

grinding and dispersing until the fineness meets the requirement;

adding the cross-linking agent, the delustring agent and the optional leveling agent under stirring, and uniformly mixing.

In yet another aspect, the present invention provides the use of an environmentally friendly one-component high temperature baking primer surfacer as described above in the field of agricultural machinery.

The beneficial effects of the invention are as follows:

The environment-friendly middle paint provided by the invention is a single-component high-temperature baking paint, the selected hydroxy acrylic resin can obviously improve the surface drying speed of the initial paint, and meanwhile, the better solvent resistance can avoid the re-dissolution phenomenon after the top paint is coated again, so that the appearance of the top paint is improved; at the same time, a small amount of hydroxyl functional groups contained can react with NCO groups of the preferable blocked isocyanate at high temperature, so that the crosslinking density of the intermediate coating is improved, and the flexibility and the adhesive force of a paint film are improved. On the basis of adopting the hydroxyl acrylic resin, the requirements of the middle-coating VOC and the sandability are combined, the corresponding filler is screened, the corresponding proportion is optimized, the solid content of the product is improved as much as possible, the luster of the product is reduced, and the surface drying speed and the sandability of the product are further improved while the requirements of the client VOC are met. According to the preferred filler, the surface characteristics of the filler and the preferred dispersing agent are combined, the intermediate coating formula is optimized, the pigment filler surface is uniformly coated with a layer of dispersing agent, the viscosity of the intermediate coating is reduced, the fluidity is improved to further reduce the construction VOC of the intermediate coating, the storage stability of the intermediate coating is ensured, the VOC requirements, the dryness and the stability of a customer site are met, and the performance of the matched finishing paint is not influenced.

Detailed Description

In order to more clearly illustrate the present invention, the present invention will be further described with reference to preferred embodiments. It is to be understood by persons skilled in the art that the following detailed description is illustrative and not restrictive, and that this invention is not limited to the details given herein.

In order to overcome the problems that in the coating in the field of agricultural machinery or light machinery, 1) single-component intercoat is difficult to ensure low VOC under the condition of high solid content and construction VOC is easy to cause exceeding standard; 2) The two-component middle coating is troublesome in operation, strict in proportioning requirement, difficult to operate in site water flowing property, and meanwhile, the follow-up high-temperature matched finish paint is baked to easily cause the problems of poor adhesive force and the like, and the embodiment provides an environment-friendly one-component high-temperature baked middle coating, wherein the raw materials of the middle coating comprise the following components in parts by weight:

22-28 parts of hydroxy acrylic resin, 1.5-2 parts of dispersing agent, 8-10 parts of pigment, 30-35 parts of filler, 8-15 parts of cross-linking agent, 2-4 parts of matting agent and 10-20 parts of organic solvent;

Wherein the solid content of the hydroxy acrylic resin is 59-65%, the hydroxyl value is 25-40mgKOH/g, the acid value is 3-8mgKOH/g, and the Tg is 45+ -5 ℃.

In some preferred examples, the hydroxyl value of the hydroxyacrylic resin is 38-40mgKOH/g, 39mgKOH/g, etc.

The hydroxyl acrylic resin in the embodiment has high solid content, low hydroxyl content, low acid value and higher Tg value, can greatly improve the surface drying speed of the intermediate coating, and simultaneously can be matched with the selected matting agent to have excellent release property on the solvent, so that the intermediate coating can be polished quickly under room temperature drying, and the production efficiency is improved; in addition, the selected filler is further combined, and the obtained intermediate paint does not influence the final gloss appearance after being matched with the finishing paint; in addition, the hydroxyl acrylic resin has no adverse effect on construction VOC, the preferable dispersing agent can obviously reduce the viscosity of the middle coating, and the filler with low oil absorption can effectively improve the solid content of the product and has small effect on the viscosity, so that the construction VOC of the middle coating is further reduced.

In some examples, the hydroxy acrylic resin is selected from one or more of FS-2060A of the modesty, ACRYDIC BU-955 of the diesely, or ACS-1063VARNISH of the Vigory.

In some examples, the dispersant is selected from polyester copolymers containing acidic groups. Preferably the dispersant is capable of significantly reducing the viscosity of the basecoat, in combination with other components, to collectively impart a lower work VOC to the basecoat. Illustratively, the dispersant includes, but is not limited to, one selected from BYK110 and the like.

In some examples, the filler is selected from precipitated barium sulfate. The precipitated barium sulfate has the characteristic of low oil absorption, can effectively improve the solid content of the product, has small influence on the viscosity, and can further reduce the construction VOC of the middle coating.

In some examples, the pigment is selected from one or more of titanium dioxide and carbon black.

In this embodiment, it has been found that the choice of crosslinker likewise significantly influences the properties of the lacquers in this embodiment. In some examples, the crosslinker is selected from the group consisting of a mixture of blocked isocyanate and epoxy crosslinker; wherein, the mass ratio of the closed isocyanate to the epoxy resin cross-linking agent is 0.375-0.5:1, and the material can be endowed with good mechanical properties such as adhesive force, impact resistance and the like when the VOC is low. If the proportion of the closed isocyanate to the epoxy resin crosslinking agent is too large, the obtained intermediate paint has poor adhesive force, impact resistance and other performances; if the ratio of the blocked isocyanate to the epoxy resin cross-linking agent is too small, the VOC requirements cannot be well met. More preferably, the mass ratio of the blocked isocyanate to the epoxy resin crosslinking agent is 0.4375:1, and the effect is better.

Illustratively, epoxy resin crosslinkers suitable for use in the present embodiment include, but are not limited to, those selected from the group consisting of E-20 epoxy resins, such as NPSN x 75 from Nanya, inc. Blocked isocyanates suitable for use in this embodiment include, but are not limited to, BL-3175, which is selected from the group of Kogyo, and the like.

The raw materials of the middle paint comprise the following components in parts by weight: 25 parts of hydroxy acrylic resin, 1.5-1.7 parts of dispersing agent, 8-10 parts of pigment, 30-35 parts of filler, 11.5 parts of cross-linking agent, 2-4 parts of matting agent and 10-20 parts of organic solvent. The addition amount of each component is controlled, so that the primer surfacer with better comprehensive properties including high solid content, low VOC, quick drying, good impact resistance, good adhesive force, appearance and the like can be obtained.

Illustratively, the matting agent may be one or more of fine talc and silica. For example TS-100 of winning company.

Illustratively, the organic solvent includes, but is not limited to, one or more selected from propylene glycol methyl ether acetate, methyl isobutyl ketone, or butyl acetate.

Illustratively, the raw materials of the middle coating paint also comprise 0.2-0.3 part of anti-settling agent and 0.02-0.06 part of leveling agent. Exemplary anti-settling agents include, but are not limited to, AEROSIL R-972, which is a winning company, and the like. Leveling agents that may be cited include, but are not limited to, GLIDE 496 selected from the winning company, and the like.

According to still another embodiment of the present invention, there is provided a method for preparing the environment-friendly one-component high-temperature baking mid-coat paint as described above, the method comprising the steps of:

Mixing part of the organic solvent, the hydroxy acrylic resin and the dispersing agent;

Optionally, adding an anti-settling agent under stirring, and continuing stirring for 5-10 minutes;

adding pigment and filler under stirring, and continuously stirring and mixing;

Adding the rest organic solvent under the stirring condition, and continuously stirring until the mixture is uniformly mixed;

grinding and dispersing until the fineness meets the requirement;

adding the cross-linking agent, the delustring agent and the optional leveling agent under stirring, and uniformly mixing.

Wherein the above "optionally" means that there may be this step or no such step. For example, when an anti-settling agent is present, there is a step of "adding the anti-settling agent under stirring, continuing stirring for 5 to 10 minutes"; if no anti-settling agent is present, this step is not present.

According to a further embodiment of the invention, there is provided the use of an environmentally friendly one-component high temperature baking primer coating as described above in the field of agricultural machinery.

The following describes the technical scheme of the present invention with reference to some specific embodiments:

Example 1

An environment-friendly single-component high-temperature baking intermediate paint comprises the following raw materials in parts by weight: 25kg of a hydroxyacrylic resin with a solid content of 60%, 9.2kg of methyl isobutyl ketone and 4.1kg of propylene glycol methyl ether acetate, 1.5kg of butyl acetate, 1.7kg of a dispersing agent, 0.25kg of an anti-settling agent, 8.4kg of a pigment, 34kg of precipitated barium sulfate, 8kg of an epoxy resin, 3.5kg of blocked isocyanate, 1.7kg of fine talcum powder, 1.2kg of matting powder and 0.05kg of a siliceous leveling agent. Reference is made in particular to table 1.

The preparation method of the environment-friendly single-component high-temperature baking mid-coat paint comprises the following steps:

(1) 25kg of hydroxy acrylic resin, 1.7kg of dispersing agent and part of solvent are added into a container with proper size, and stirred (400-600 rpm) for 10-15 minutes;

(2) Adding 0.25kg (400-600 rpm) of anti-settling agent for 5-10 minutes while stirring;

(3) Adding 8.4kg of pigment and 34kg of filler while stirring, and stirring (400-600 rpm) for 10-15 minutes after the pigment and the filler are added;

(4) Adding the residual solvent into the container wall while stirring, and continuously stirring for 30 minutes until the residual solvent is uniform;

(5) Starting grinding and dispersing on a designated sand mill until the fineness meets the requirement;

(6) Adding the cross-linking agent, the leveling agent and the flatting agent while stirring, and stirring for 5-10 minutes until the fineness meets the requirement.

The midway paint is detected according to a middle coating detection operation instruction, and all main technical indexes are shown in table 2.

Example 2-example 5

The middle coating components of each example are shown in Table 1, the preparation method of each example is basically the same as that of example 1, and the technical indexes of the prepared coating are shown in Table 2.

TABLE 1

Reference example 1

Example 1 was repeated except that the dispersant used was changed to a polycarboxylate solution of polyamine amide (ANTI-tera-204), and the other components were the same as in example 1, to prepare a primer surfacer.

Reference example 2

Example 1 was repeated except that the hydroxy acrylic resin used was changed to a high solids low viscosity resin: NP 023RBX3875 resin (75% solids, hydroxyl content 4%, tg about 20 ℃ C.), the other ingredients were the same as in example 1, and a primer surfacer was prepared.

Reference example 3

Example 1 was repeated except that the whole of the hydroxyacrylic acid resin and the crosslinking agent was replaced with a macromolecular epoxy resin (ARAKYD 9216,316 resin) in the same amount, and the other components were the same as those of example 1, to prepare a primer surfacer.

Reference example 4

Example 1 was repeated except that the crosslinking agent was changed to a high iminomelamine resin instead of the blocked isocyanate resin, and the other components and the preparation method were the same as in example 1, to prepare a middle coating paint.

Reference example 5

Example 1 was repeated except that no blocked isocyanate was added, 0.02 part of dibutyltin dilaurate catalyst was added, and the other components and the preparation method were the same as in example 1, above as component A; the component B is HDI resin with 40 percent of solid content; a: b=12: 1 (weight ratio), a middle coating is prepared.

Reference example 6

Example 1 was repeated except that the hydroxy acrylic resin used as the high-solids low-viscosity resin (75% solids, hydroxyl content 4%, tg about 20 ℃ C.) used in comparative example 2 was used, blocked isocyanate and epoxy resin were not added, 0.02 part of dibutyltin dilaurate catalyst was added, and the other components were the same as in example 1, above as component A; the component B is 55% HDI resin solution, A: B=5:1 (weight ratio), and the intermediate paint is prepared.

Experimental example 1

The base paint data for each mid-coat paint was tested according to the factory inspection standard for mid-coat paint and the test results are shown in table 2.

TABLE 2

Experimental example 2

According to the field construction process, the relevant performance of each example is tested, the parameters of the matched product are shown in Table 3, and the relevant performance is shown in Table 4.

TABLE 3 Table 3

Coating layer	Model number	Film thickness/. Mu.m	Baking conditions
				Electrophoresis	3200 Grey electrophoretic paint (Libang)	10-15	160℃*20min
Middle coating	Intermediate paint prepared in the above examples or reference examples	15-25	Room temperature 55min
				Finishing paint	SP 300H red finish paint	25-40	160℃*40min

TABLE 4 Table 4

(In the above table, "/" indicates no measured pot life, since no single component generally measures pot life, two components only consider the increase in gel viscosity in the production reaction)

From the above experimental data, it can be seen that examples 1-3 all meet customer site requirements, wherein example 1 has better overall performance than examples 2 and 3, and examples 4-5 also meet customer requirements using the same type of acrylic resin. The viscosity reduction effect of the formula with a high pigment and filler proportion is poor by using a common dispersing agent in the reference example 1, and the construction VOC can not meet the requirements; the high-solid low-viscosity resin used in the reference example 2 can effectively reduce construction VOC, but is slow to dry at normal temperature and cannot meet the polishing requirement; reference example 3 is an old product before replacement, and has very good grindability and corollary property, but the construction VOC is seriously out of standard and cannot be used; reference example 4 curing with melamine amino resin reduces the adhesion and flexibility of the product; the reference example 5 is a two-component product, the grindability and the construction VOC can meet the requirements, but the operation time is short, and the batch use is not easy in the field; the reference example 6 adopts high-solid low-viscosity resin, has lower viscosity and higher hydroxyl content, has low construction VOC and quick drying speed, but has short operable time, and can solve the serious adhesion problem when matched with high-temperature baking finish paint, thus being not applicable to the process.

It should be understood that the foregoing examples of the present invention are provided merely for clearly illustrating the present invention and are not intended to limit the embodiments of the present invention, and that various other changes and modifications may be made therein by one skilled in the art without departing from the spirit and scope of the present invention as defined by the appended claims.

Claims (10)

1. The environment-friendly single-component high-temperature baking intermediate paint is characterized by comprising the following components in parts by weight:

22-28 parts of hydroxy acrylic resin, 1.5-2 parts of dispersing agent, 8-10 parts of pigment, 30-35 parts of filler, 8-15 parts of cross-linking agent, 2-4 parts of matting agent and 10-20 parts of organic solvent;

Wherein the solid content of the hydroxy acrylic resin is 59-65%, the hydroxyl value is 25-40mgKOH/g, the acid value is 3-8mgKOH/g, and the Tg is 45+ -5 ℃.

2. The environmentally friendly one-component high temperature baking primer surfacer of claim 1, wherein the dispersant is selected from the group consisting of polyester copolymers containing acidic groups.

3. The environment-friendly single-component high-temperature baking intermediate paint according to claim 1, wherein the pigment is one or more selected from titanium pigment and carbon black; and/or

The filler is selected from precipitated barium sulfate.

4. The environmental-friendly one-component high-temperature baking mid-coat paint according to claim 1, wherein the hydroxyl acrylic resin is one or more selected from the group consisting of FS-2060A of courtesy, ACRYDIC BU-955 of diease and ACS-1063 varish of libon.

5. The environmentally friendly one-component high temperature baking mid-coat paint of claim 1, wherein said crosslinker is selected from the group consisting of a mixture of blocked isocyanate and epoxy crosslinker; wherein the mass ratio of the blocked isocyanate to the epoxy resin cross-linking agent is 0.375-0.5:1.

6. The environmentally friendly one-component high temperature baking primer surfacer of claim 5, wherein said epoxy cross-linking agent is selected from the group consisting of E-20 epoxy.

7. The environment-friendly single-component high-temperature baking intermediate paint as claimed in claim 1, wherein the raw materials of the intermediate paint comprise the following components in parts by weight:

25 parts of hydroxy acrylic resin, 1.5-1.7 parts of dispersing agent, 8-10 parts of pigment, 30-35 parts of filler, 11.5 parts of cross-linking agent, 2-4 parts of matting agent and 10-20 parts of organic solvent.

8. The environment-friendly one-component high-temperature baking intermediate paint according to claim 1, wherein the raw materials of the intermediate paint further comprise 0.2-0.3 part of anti-settling agent and 0.02-0.06 part of leveling agent.

9. The method for preparing the environment-friendly one-component high-temperature baking mid-coat paint as claimed in any one of claims 1 to 8, comprising the following steps:

Mixing part of the organic solvent, the hydroxy acrylic resin and the dispersing agent;

Optionally, adding an anti-settling agent under stirring, and continuing stirring for 5-10 minutes;

adding pigment and filler under stirring, and continuously stirring and mixing;

Adding the rest organic solvent under the stirring condition, and continuously stirring until the mixture is uniformly mixed;

grinding and dispersing until the fineness meets the requirement;

adding the cross-linking agent, the delustring agent and the optional leveling agent under stirring, and uniformly mixing.

10. Use of the environmentally friendly one-component high temperature baking primer coating as claimed in any of claims 1 to 8 in the field of farm machinery.