KR100496049B1 - Thermosetting Urethane Modified Polyester Resin Composition - Google Patents

Abstract

      A thermosetting urethane-modified polyester resin coated on the undercoat of a PCM (Pre Coated Metal) steel sheet used for home appliances or building materials is disclosed. The resin is obtained by addition reaction of an isocyanate compound with a polyester resin equivalent ratio of 20 to 80% to a polyester resin having a hydroxyl value of 10 to 50 mgKOH / g and a weight average molecular weight of 5,000 to 20,000. The present invention relates to a urethane-modified polyester resin composition for PCM steel plate undercoating, which is used as a resin composition of a coating material having excellent workability after coating of a coat and a top coat, and having a painted coat having excellent adhesion to a coat or a base.

Description

      Thermosetting Urethane Modified Polyester Resin Composition

      The present invention relates to a thermosetting urethane-modified polyester resin coated on the undercoat of a PCM (Pre Coated Metal) steel sheet used for home appliances or building materials. More specifically, the present invention is a resin composition of a coating material which is excellent in workability after coating the upper and upper coats, and the coated coat has excellent adhesion to the upper coat and the base, and is used for the PCM steel sheet undercoating used by mixing a main material and a curing agent. It relates to a urethane-modified polyester resin composition.

      In general, resins for PCM steel coating paints are acrylic, urethane, epoxy, polyester, silicone, fluorine, polyvinyl chloride, etc., and most of the paints used are thermosetting paints and require special physical properties. In addition to the products, polyester and epoxy are used a lot, and among them, a paint using a polyester resin is most used.

      In PCM steel plate paints, the following properties are required. First, the mechanical properties such as workability, pencil hardness, adhesion to the base or top, frictional MEK resistance, and the like, and second, chemical properties such as acid resistance, alkali resistance, and weather resistance, and third, productivity and cost are determined. Workability should be excellent

      PCM steel plate undercoat coatings used so far are mainly made of polyester and epoxy paints. Polyester-based paints for PCM steel undercoating have excellent workability after top coat coating and other excellent chemical resistance and workability, but have poor scratchability due to poor adhesion to top coat or substrate, and also for PCM steel undercoating. Epoxy-based paints have particularly good adhesion to top coats or substrates, and thus have excellent scratch properties, but have poor workability than polyester paints.

      Due to the difference in the physical properties of the polyester and epoxy paints, the PCM steel plate paints are separated from the paints used for home appliances and the paints used for building materials. There is a need for an integrated undercoat using the advantages of polyester and epoxy based undercoats.

      Therefore, the object of the present invention is to improve the adhesion with the top coat or the base, which is a problem of the conventional polyester paint for PCM steel plate undercoat, and to improve the processability, which is a problem of epoxy-based paint for PCM steel plate undercoat, dualizing for home appliances and building materials The present invention provides a thermosetting urethane-modified polyester resin suitable for a coating composition incorporating a PCM steel coating material.

In order to achieve the above object of the present invention, in the present invention, the isocyanate compound is 20 to 80% of the total equivalent of the polyester resin in a polyester resin having a hydroxyl value of 10 to 50 mgKOH / g and a weight average molecular weight of 5,000 to 20,000. Obtained by addition reaction, wherein the polyester resin is 55 to 95% of the aromatic acid in the equivalent of the total acid and the glycol comprising 25 to 95% of the first glycol and 5 to 75% of the second glycol in the total glycol equivalent weight. And it provides an urethane-modified polyester resin composition characterized in that the acid (acid) containing 5 to 45% aliphatic acid formed by condensation reaction.

When the PCM steel sheet undercoat coating material is manufactured by using the thermosetting urethane-modified polyester resin composition according to the present invention, when the PCM steel sheet undercoat is coated, the problem of poor adhesion to the base or top coat of the existing polyester paint, and epoxy paint Can improve the problem of poor workability.

Hereinafter, the present invention will be described in detail.

The thermosetting urethane-modified polyester resin according to the present invention is to improve the workability and the adhesion between the base material or the top for the PCM steel plate undercoat. That is, in order to solve the problem of poor adhesion or adhesion with the base material or the top coat of polyester paints used as the existing PCM steel plate undercoat, the hydroxyl value is 10 to 50 mgKOH / g and the weight average molecular weight is The urethane-modified polyester resin composition obtained by addition-reacting 20-80% of an isocyanate compound with respect to a polyester resin equivalent ratio to the polyester resin which is 5,000-20,000 is used. The paint containing the resin of the present invention can be used as an integrated PCM steel undercoat paint with improved workability and adhesion to the top and bottom.

Examples of the glycol component of the thermosetting polyester resin include ethylene glycol, propylene glycol, 1,4 butylene glycol, 1,6 hexanediol, neopentyl glycol, methyl propanediol, cyclohexanedimethanol, hydrogenate bisphenol A, and ethylene oxide. Addition bisphenol A, propylene oxide addition bisphenol A, ethylene oxide addition bisphenol F, propylene oxide addition bisphenol F, ethylene oxide addition bisphenol S, propylene oxide addition bisphenol S, etc. are mentioned. These may be used by mixing one or more than two.

Preferably, the glycol used in the thermosetting urethane-modified polyester resin comprises 20 to 100% of the total glycol equivalent of the first glycol comprising at least one of ethylene glycol, neopentyl glycol, methylpropanediol, propylene glycol, 1.4 butyl The second glycols comprising at least one of ene glycol, 1.6 hexanediol cyclohexanedimethanol, and hydrogenate bisphenol A comprise 0 to 80% of the total glycol equivalents.

Examples of the acid used in the preparation of the thermosetting urethane-modified polyester resin include phthalic anhydride, tetrahydro phthalic anhydride, isophthalic acid, terephthalic acid, adipic acid, azelaic acid, sebacic acid, cyclohexadieside, trimelli Tic anhydride, and the like. These can be used individually or in mixture of 2 or more types.

Preferably, the acid is 50 to 100% of the total acid equivalent of an aromatic acid including at least one selected from the group consisting of phthalic anhydride, tetrahydro phthalic anhydride, isophthalic acid and terephthalic acid. Aliphatic acid comprising at least one selected from the group consisting of diflic acid, azelaic acid, sebacic acid and cyclohexadieside comprises from 0 to 50% of the total acid equivalent.

When the hydroxyl value of the said polyester resin is less than 10 mgKOH / g, sclerosis | hardenability is inferior and it is not preferable, and when it exceeds 50 mgKOH / g, it is unpreferable since the workability of a cured coating film falls. Moreover, when the weight average molecular weight of the said polyester is less than 5000, it is not preferable because the workability of a cured coating film is bad, and when it exceeds 20000, since resin viscosity is too high and workability worsens, it is not preferable. Therefore, the hydroxyl value of the polyester resin is 10 to 50 mgKOH / g and the weight average molecular weight should be 5,000 to 20,000.

      As isocyanate which addition-reacts with the said polyester resin, 2, 4-toluene diisocyanate, 2, 6-toluene diisocyanate, 4,4'- diphenyl methane diisocyanate, 2,4'- diphenyl methane diisocyanate, poly Methylene polyphenylene polyisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, tetramethyl xylene diisocyanate, etc. are mentioned. These can be used individually or in mixture of 2 or more types.

If the urethane modification ratio is 20% or less, the effect of introducing urethane is not expected to be large. If the urethane modification ratio is 80% or more, less hydroxyl groups remain in the resin after modification, resulting in poor curing resistance during the melamine curing reaction, resulting in poor MEK resistance. Therefore, the modification ratio of the isocyanate compound to the polyester resin (equivalent ratio to the alcohol residue) may be additionally modified from 20 to 80% with respect to the equivalent ratio of the polyester resin.

The thermosetting urethane-modified polyester resin composition of the present invention is designed to have a hydroxyl value of 10 to 50 mgKOH / g and a weight average molecular weight of 5,000 to 20,000 using the glycol and acid described above, and the isocyanate compound is equivalent to the polyester resin equivalent ratio. It is addition denaturing in 20 to 80% of the ratio.

      Hereinafter, the present invention will be described in detail through specific examples.

Preparation of Thermosetting Polyester Resins

Synthesis Example 1

A 5-liter four-necked flask was equipped with a thermometer, a condenser, a stirrer, a water removal condenser and a temperature raising device. Here, 272 g of neopentyl glycol, 358 g of cyclohexanedimethanol (90%), 308 g of 1,6-hexanediol, 774 g of isophthalic acid, and 339 g of terephthalic acid were mixed and gradually heated up to 240 ° C., with a hydroxyl value of 29 mgKOH as a condensation reaction. 1825 g of a thermosetting polyester resin having a weight average molecular weight of 15,000 g / g was obtained.

Synthesis Example 2

      A 5-liter four-necked flask was equipped with a thermometer, a condenser, a stirrer, a water removal condenser and a temperature raising device. Neopentylglycol 582g, 279g of 1,6-hexanediol, 499g isophthalic acid, 499g terephthalic acid, 499g adipic acid were mixed and gradually warmed up to 240 ° C with condensation reaction and the hydroxyl value was 25 mgKOH / g by condensation reaction and the weight average molecular weight 2074 g of this 20,000 thermosetting polyester resin was obtained.

Synthesis Example 3

      A 5-liter four-necked flask was equipped with a thermometer, a condenser, a stirrer, a water removal condenser and a temperature raising device. Here, 308 g of neopentyl glycol, 240 g of cyclohexanedimethanol (90%), 354 g of 1,6-hexanediol, 775 g of isophthalic acid, 775 g of terephthalic acid, and 399 g were gradually stirred, and the temperature was raised to 240 ° C. The hydroxyl value of the condensation reaction was 29 mgKOH. 1825 g of a thermosetting polyester resin having a / g and a weight average molecular weight of 18,000 were obtained.

Synthesis Example 4

A 5-liter four-necked flask was equipped with a thermometer, a condenser, a stirrer, a water removal condenser and a temperature raising device. Neopentylglycol 502g, 1,6-hexanediol 387g, isophthalic acid 849g, terephthalic acid 438g was mixed and gradually stirred, the temperature was raised to 240 ℃ by condensation reaction of the hydroxyl value of 24 mgKOH / g and a weight average molecular weight of 17,000 1900 g of thermosetting polyester resins were obtained.

Preparation of Urethane Modified Polyester Resin

Example 1

A 2-liter four-necked flask was attached with a thermometer, a condenser, a stirrer, and a temperature raising device. 500 g of the synthesized Example 1 polyester resin was added thereto, diluted and dissolved in 750 g of an aromatic solvent, Cocozol-150, and then 12 g of tetramethylxylene diisocyanate, an isocyanate compound, was added thereto and reacted at 70 ° C. to modify the urethane-modified polyester. A resin was obtained.

Example 2

A 2-liter four-necked flask was attached with a thermometer, a condenser, a stirrer, and a temperature raising device. 500 g of the synthesized Example 3 polyester resin was added thereto, diluted with 750 g of cocosol-150, which is an aromatic solvent, and dissolved. Then, 13 g of tetramethylxylene diisocyanate, which is an isocyanate compound, was added and reacted at 70 ° C. to modify the urethane-modified polyester. A resin was obtained.

Example 3

A 2-liter four-necked flask was attached with a thermometer, a condenser, a stirrer, and a temperature raising device. 500 g of the synthesized Example 3 polyester resin was added thereto, diluted with 750 g of cocosol-150, which is an aromatic solvent, and dissolved. Then, 13 g of tetramethylxylene diisocyanate, which is an isocyanate compound, was added and reacted at 70 ° C. to modify the urethane-modified polyester. A resin was obtained.

Example 4

A 2-liter four-necked flask was attached with a thermometer, a condenser, a stirrer, and a temperature raising device. 500 g of the synthesized Example 4 polyester resin was added thereto and diluted with 750 g of an aromatic solvent, Cocosol-150, and then 13 g of tetramethylxylene diisocyanate, an isocyanate compound, was added thereto, followed by reaction at 70 ° C. for a urethane-modified polyester. A resin was obtained.

Coating characteristic test

Manufacture of paint

In order to examine the characteristics of the thermosetting urethane-modified polyester resin for painting the PCM steel sheet undercoat obtained in each of the above-described coating, a coating material for home appliances including the resin composition obtained in Examples 1 to 4 and a melamine curing agent was prepared. . Table 1 shows the composition ratio of the paint including the thermosetting urethane-modified polyester resin and the melamine curing agent.

Raw material name Compounding amount Resin of Examples 1 to 4 60 TiO ₂ 10 Strontium Chromate 10 Dispersant 0.2 Melamine curing agent 3.0 Acid catalyst 0.3 Antifoam 0.5 menstruum 16 Sum 100

In Table 1, EFKA-4050 (trade name of EFKA Corporation) was used as a dispersant, Cymel-303 (trade name of CYTEC) as a melamine curing agent, Nacure-5225 (trade name of KING Corporation) was used as an acid catalyst, and EFKA-2021 (antifoaming agent) was used. EFKA brand name) was used, and cyclohexanone, xylene, and butyl cellosolve (mixture ratio: 40/30/30) were used as a solvent.

      For comparison, the contents of each component used in the conventional PCM steel plate undercoat polyester paint and epoxy paint are prepared as shown in Tables 2 and 3 to prepare the paints of Comparative Examples 1 and 2.

Raw material name Compounding amount Polyester resin 35 TiO ₂ 10 Strontium Chromate 10 Dispersant 0.2 Melamine curing agent 2.0 Acid catalyst 0.3 Antifoam 0.5 Solvent 42 Sum 100

In Table 2, NORUESTER-1000 (trade name of Deepia Co., Ltd.) was used as the polyester resin, and other components used the same material as described for Table 1 above.

Raw material name Compounding amount Epoxy resin 25 TiO ₂ 8 Strontium Chromate 12 Dispersant 0.1 Melamine curing agent 2.0 Acid catalyst 0.1 Antifoam 0.3 Solvent 52.5 Sum 100

In Table 3, NORUPOXY-2210 (trade name of Diffia Inc.) was used as the epoxy resin, and other components used the same material as described for Table 1 above.

Coating was performed on the steel plate using the coating material comprising the resin composition of Examples 1 to 4 and the coating materials prepared in Comparative Examples 1 and 2.

In this case, zinc phosphate-treated steel sheets were used, and the thickness of the coating film was 5 ± 2 μm. The surface temperature of the substrate was 224 ° C., and the content of hydroxyl group was 0.5-1% and the molecular weight was 13,000. , PCM steel sheet topcoat made of a thermosetting resin having a Tg of 12 ° C. was used.

After coating the above-mentioned undercoat, the top coat of PCM steel sheet was coated to test the properties of the coating film. The test results are shown in Table 4 below.

Used paint Paint including the resin of Example 1 Paint including the resin of Example 2 Paint including the resin of Example 3 Paint including the resin of Example 4 Paint of Comparative Example 1 (including polyester resin) Paint of Comparative Example 2 (Including Epoxy Resin) Glossy (60 °) 91 91 92 91 91 87 MEK Rubbing 100 or more 100 or more 100 or more 100 or more 100 or more 100 or more Machinability 1T 1T 1T 2T 2T 4T Pencil hardness H H H H H H Adhesion 100/100 100/100 100/100 100/100 100/100 100/100 Acid resistance Good Good Good Good Good Good Alkali resistance Good Good Good Good Good Good Boiling water resistance Good Good Good Good Good Good Body, top adhesion ◎ ◎ ◎ ◎ △ ◎

      In Table 4, an evaluation item indicating characteristics of each paint means the following. ◎ is very good, ○ is good, △ is normal and X is poor in the item of adhesiveness with base or top.

      In addition, each characteristic in Table 4 was measured by the following method. First, gloss is ASTM-D-523, MEK Rubbing is NCCA-II-18, processability is NCCA-II-19, pencil hardness is NCCA-II-12, and in case of adhesion, NCCA-II-20, acid resistance In the case of alkali resistance, it was measured by the method in ASTM-D-1308.

      In addition, the measurement of boiling water resistance was performed by immersion in boiling water for 24 hours, and then the state of the changed coating film was visually determined.

      As a method of measuring adhesion to the body or the top coat, the degree of adhesion of the body or the top coat with the coin was scratched by pressing with the same force, and visually discriminated.

      As shown in the above table, the coating material containing the resin of Comparative Example 1 is poor in adhesion to the base material and top coat, and the coating material containing the resin of Comparative Example 2 is good in the adhesiveness of the base top coat but poor in terms of gloss. . However, in the case of the coating material containing the resin of Examples 1-4, while being excellent in glossiness, adhesiveness with respect to a base and top coat was also favorable.

Therefore, when the PCM steel sheet undercoat coating material is prepared using the thermosetting urethane-modified polyester resin composition according to the present invention, when the PCM steel plate undercoat is coated, the problem of poor adhesion or adhesion with the existing polyester-based paint and epoxy The problem that the workability of the system paint is poor can be improved. Therefore, it is possible to integrate and use the dual coating material

Claims (7)

Isocyanate compound is obtained by addition reaction 20 to 80% of the total equivalent of the polyester resin to a polyester resin having a hydroxyl value of 10 to 50 mgKOH / g and a weight average molecular weight of 5,000 to 20,000, The polyester resin is 55 to 95% of the aromatic acid and 5 to 45% of the aliphatic acid in the equivalent of the total acid and the glycol comprising the first glycols 25 to 95% and the second glycols 5 to 75% of the total glycol equivalent Acid-containing containing is formed by condensation reaction urethane-modified polyester resin composition, characterized in that. delete delete The method of claim 1, wherein the first glycol of the glycol is at least one selected from the group consisting of ethylene glycol, neopentyl glycol and methyl propanediol, the second glycol is propylene glycol, 1.4 butylene glycol, 1.6 hexanediol, A thermosetting polyester resin composition, characterized in that at least one selected from the group consisting of cyclohexane dimethanol and hydrogenate bisphenol A. delete The method of claim 1, wherein the aromatic acid is at least one selected from the group consisting of phthalic anhydride, tetrahydro phthalic anhydride, isophthalic acid and terephthalic acid, the aliphatic acid is adipic acid, azelaic acid, seba Thermosetting polyester resin composition, characterized in that it comprises at least one selected from the group consisting of sacid and cyclohexadieside. The method of claim 1, wherein the isocyanate compound is 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 4,4'-diphenyl methane diisocyanate, 2,4'-diphenyl methane diisocyanate, tetra Urethane-modified polyester resin composition, characterized in that at least one selected from the group consisting of methyl xylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate.