KR20060074068A - Pre coated metal coating polyester resin and method of preparing the same - Google Patents

Abstract

Disclosed is a polyester resin composition for PCM coatings having excellent chemical resistance and moisture resistance after coating, and particularly excellent workability. The polyester resin for PCM coating is a glycol comprising 5 to 40% of the first glycol and 60 to 95% of the second glycol mixed with 1,3-cyclohexanedimethanol and 1,4-cyclohexanedimethanol based on the total equivalent weight of glycol. A diacid mixture comprising a mixture and an aromatic acid, aliphatic acid or a mixture thereof is formed by condensation in a ratio of 1.0: 1.0 to 1.1 equivalents. The polyester resin composition for thermosetting PCM paint is excellent in adhesion to the top coat and the base, and particularly excellent in workability.

Description

Polyester resin for PCM paint and its manufacturing method {PRE COATED METAL COATING POLYESTER RESIN AND METHOD OF PREPARING THE SAME}

The present invention relates to a polyester resin and a method for manufacturing the same, and more particularly, to a polyester resin for PCM paint used as a coating composition for the coating of the PCM (Pre Coated Metal) steel sheet for home appliances, and a method for producing the same.

Resin compositions for PCM steel sheet coating generally used are acrylic, urethane, epoxy, polyester, silicone, fluorine, polychlorinated and the like. Most of the paint is thermosetting, except for a product that requires the properties of special paints, polyester and epoxy resin compositions are used a lot, and in particular, paints using a polyester resin is most used.

The following physical properties are calculated | required by the resin composition of the coating material coat | covered by the undercoat of a PCM steel plate. First, mechanical properties such as adhesion to the base or top coat after coating, degree of flexibility, mechanical resistance such as friction MEK (methyl ethyl ketone), and second, chemical properties such as acid resistance, alkali resistance and weather resistance. In addition, productivity and cost dependability and workability should also be excellent.

The resin composition for undercoat coating of PCM steel plate used so far is mainly a polyester type and an epoxy type. Polyester coating for PCM steel plate undercoat is excellent in workability after top coat and other chemical resistance, workability, etc., but poor scratchability due to poor adhesion to the top coat or the base.

In addition, the epoxy coating for PCM steel plate undercoat is particularly excellent in adhesion to the top coat or the base material has excellent scratch resistance but poor workability than polyester-based paint. Therefore, in the meantime, due to the difference in the physical properties of the polyester-based and epoxy-based paint for coating as described above, there is a difficulty that should be used in consideration of the resin used in the paint for PCM steel coating.

Therefore, the first object of the present invention for solving the above problems is to improve the adhesion, moisture resistance and the like to the base or top, polyester resin for PCM coatings that can improve the low workability which is a problem of the epoxy resin composition To provide.

In addition, a second object of the present invention is to provide a method for producing a polyester resin for PCM paint having the above-described physical properties.

PCM paint polyester resin according to an embodiment of the present invention for achieving the first object is a first glycol mixed with 1,3-cyclohexanedimethanol and 1,4-cyclohexanedimethanol based on the total glycol equivalent A glycol mixture comprising 5-40% and 60-95% of the second glycol and a diacid mixture comprising aromatic acids, aliphatic acids or mixtures thereof are formed condensed in a ratio of 1.0: 1.0 to 1.1 equivalents.

In addition, in the method for producing a polyester resin for PCM paint according to an embodiment of the present invention for achieving the second object, 1,3-cyclohexanedimethanol and 1,4-cyclohexane relative to the total equivalent glycol A glycol mixture comprising 5-40% of the first glycol mixed with 60-95% of the second glycol is formed. Subsequently, a diacid mixture comprising an aromatic acid, aliphatic acid or a mixture thereof is formed. Subsequently, the thermosetting polyester resin is prepared by condensing the glycol mixture and the diacid mixture in a ratio of 1.0: 1.0 to 1.1 equivalents.

Accordingly, the polyester resin for PCM paint of the present invention and a method of manufacturing the same have problems of poor moisture resistance, poor adhesion to base material and top coat, and processability of epoxy-based paints of existing polyester paints used as PCM steel plate paints. Poor problem can be solved. That is, the polyester resin composition for thermosetting curable PCM coatings which improved the adhesiveness with the topability of a coating material, and moisture resistance can be provided.

Hereinafter, the present invention will be described in more detail.

The polyester resin for PCM paint of the present invention is a thermosetting polyester resin applied to PCM paint for coating, and 5 to 40% of first glycol mixed with 1,3-cyclohexanedimethanol and 1,4-cyclohexanedimethanol It is formed by the condensation reaction of a glycol mixture comprising 60 to 95% di glycol and a diacid mixture comprising aromatic acid, aliphatic acid or a mixture thereof.

First, the glycol compound is a mixture of 5 to 40% of the first glycol and 60 to 95% of the second glycol relative to the total glycol equivalent. The first glycol is 1,3-cyclohexanedimethanol represented by the following formula (1) and 1,4-cyclohexanedimethanol represented by the following formula (2) (1, 4-Cyclohexanedimethanol) is a glycol compound having a structure in which the ratio is 1: 1 (50%: 50%).

------(1)

------(2)

------(One)

------(2)

The glycol compound (Mixed cyclohexane dimethanol) has good solubility and reactivity in the synthesis of resin, chemical resistance, moisture resistance, etc., has higher hardness than neopentyl glycol, excellent acid resistance, improved impact resistance, similar flexibility (Flexibility) In addition, it is a glycol compound that has good solubility, low viscosity, and particularly good flexibility than conventional 1,4-cyclohexanedimethanol, which helps to improve processability and adhesion.

The second glycol is, for example, cyclohexanedimethanol, ethylene glycol, propylene glycol, methyl propanediol, neopentyl glycol, 1,4-cyclohexanedimethylol, 1,6-hexanediol, bisphenol A added with ethylene oxide, and the like. For example. These can be used individually or in mixture.

The glycol mixture comprising the first glycol and the second glycol is a PCM paint for coating comprising the polyester resin of the present invention when the total glycol content is less than 5% or the second glycol content is more than 95%. There is a problem that the adhesion, processability, chemical resistance, moisture resistance and the like is inferior. On the other hand, when the content of the first glycol is more than 40%, or the content of the second glycol is less than 60%, there is a problem that the coin scratchability and MEK rubbing property of the PCM coating material coating film falls.

Thus, the glycol mixture comprises 5-40% of the first glycol and 60-95% of the second glycol. Preferably the glycol mixture comprises 10 to 35% of the first glycol and 65 to 90% of the second glycol.

In addition, the diacid mixture applied to prepare the polyester resin for PCM paint of the present invention includes an aromatic acid, aliphatic acid or a mixture thereof.

Examples of the aromatic acid contained in the diacid mixture include phthalic anhydride, tetrahydro phthalic anhydride, isophthalic acid, terephthalic acid, and the like, and these are used alone or in combination. The aliphatic acid contained in the diacid includes, for example, sebacic acid, adipic acid, azelic acid, trimellitic anhydride, and the like.

In general, the aromatic acid has excellent hardness but lacks flexibility, and the aliphatic acid tends to have excellent flexibility but low hardness. The target quality in the coating composition is that it is preferable that the hardness of the pencil hardness F or more in the case of hardness, that is, the degree of cracking does not occur in 2T in the case of flexibility, namely workability.

Therefore, in the present invention, a biaddition mixture using an appropriate combination of high and high hardness aromatic acids and highly flexible aliphatic diacids can exhibit sufficient hardness and flexibility.

Specifically, the diacid mixture comprises 50 to 100% of the total equivalent of at least one aromatic acid selected from the group consisting of phthalic anhydride, tetrahydro phthalic anhydride, isophthalic acid and terephthalic acid. . In addition, the diacid mixture comprises 0-50% of the total equivalent of at least one aliphatic acid selected from the group consisting of sebacic acid, adipic acid, azelic acid.

Thus, it is preferred that the diacid mixture comprises 50-100% of the total equivalent of diacid, and aliphatic acid comprises 0-50% of the total equivalent of diacid. It is more preferred that the aromatic acid comprises 55 to 95% and the aliphatic acid comprises 5 to 45% of the total equivalent of the diacid mixture.

When the mixing equivalent ratio of the diacid mixture is less than 1.0: 1.0 for the glycol mixture of the present invention, that is, when the content of the glycol mixture is more than the content of the diacid mixture, the paint containing the polyester resin of the above-mentioned real name is coated on the PCM steel plate under the coating. Adhesion with the substrate or the top coat is not satisfactory. On the other hand, when the mixing equivalence ratio of the diacid mixture is more than 1.0: 1.1 to the glycol mixture, that is, when the content of the diacid mixture is more than 10% of the glycol content, the chemical resistance such as processability and water resistance during coating becomes poor. Has

Accordingly, the glycol mixture and the diacid mixture preferably have a mixing equivalent ratio of 1.0: 1.0 to 1: 1, and more preferably a mixed equivalent ratio of 1.0: 1.0 to 1.05.

The polyester-based resin for PCM paint of the present invention has a molecular weight of the polyester resin for PCM paint has a hydroxy value of 19 to 21, an acid value of 5 or less, Gardner viscosity of Z-Z3, and an average molecular weight of 10,000 to 35000. It is desirable to have.

Here, when the molecular weight of the polyester-based resin for PCM paint is less than 10,000, workability and hardness are lowered, and when the molecular weight is more than 35,000, the solid content of the paint is lowered due to incompatibility with a solvent applied for viscosity and workability. There is a problem that the lower the high speed workability of the PCM line. Therefore, the molecular weight of the polyester resin has a 10,000 to 35,000 and preferably has a molecular weight of 15000 to 30,000.

Manufacturing method of polyester resin for PCM coating

First, a glycol mixture comprising 5 to 40% of the first glycol and 60 to 95% of the second glycol mixed with 1,3-cyclohexanedimethanol and 1,4-cyclohexanedimethanol is formed based on the total equivalent glycol. Since the description of the first glycol, the second glycol and the glycol mixture has been described in detail above, it is omitted to avoid duplication.

Subsequently, a diacid mixture comprising an aromatic acid, aliphatic acid or a mixture thereof is formed. The biadditive mixture of the present invention uses a combination of high hardness aromatic acid and aliphatic acid with excellent flexibility so as to exhibit sufficient hardness and flexibility of the coating film to be formed. Specifically, the diacid mixture preferably contains 50 to 100% of the total equivalent of diacid, and aliphatic acid comprises 0 to 50% of the total equivalent of diacid. More preferably, 55 to 95% of aromatic acids, and 5 to 45% of the total equivalent of the diacid mixture are preferred.

Subsequently, the glycol mixture and the diacid mixture are condensed with each other in a ratio of 1.0: 1.0 to 1.1 equivalents to form a thermosetting polyester resin. The thermosetting polyester resin applied to the PCM paint formed by the above method has a hydroxy value of 19 to 21, an acid value of 5 or less, a Gardner viscosity of Z-Z3 and an average molecular weight of 10,000 to 35000.

Hereinafter, the present invention will be described in detail through specific examples and experimental examples. However, the present invention is not limited to the following examples and synthesis examples, of course.

Example 1

A 2-liter four-necked flask was equipped with a thermometer, condenser, stirrer and condenser and a temperature raising device was attached. To this was added a glycol mixture containing 148 g of neopentyl glycol, 42 g of 1,6-hexanediol, 129 g of butylene glycol, and 50 g of cyclohexanedimethanol, and a diacid mixture containing 71 g of adipic acid and 486 g of isophthalic acid. It heated up to 240 degreeC, stirring. Thereafter, a condensation reaction was performed for about 7-8 hours to obtain a thermosetting polyester resin having a hydroxyl value of 21, an acid value of 5, and a viscosity (Gardner) of Z-Z1.

Example 2

A 2-liter four-necked flask was equipped with a thermometer, condenser, stirrer and condenser and a temperature raising device was attached. Here, a glycol mixture containing 223 g of neopentyl glycol, 59 g of 1,6-hexanediol, and 57 g of ethylene glycol was added thereto, and a diacid mixture containing 71 g of adipic acid and 355 g of isophthalic acid and 355 g of terephthalic acid was added thereto. It heated up as. Thereafter, a condensation reaction was performed for about 7 to 8 hours to obtain a thermosetting polyester resin having a hydroxyl value of 22, an acid value of 4, and a viscosity (Gardner) of V-.

Example 3

A 2-liter four-necked flask was equipped with a thermometer, condenser, stirrer and condenser and a temperature raising device was attached. To this was added a glycol mixture containing 244 g of neopentyl glycol and 270 g of bisphenol A having an equivalent of 2 mol of ethylene oxide, and a diacid mixture containing 117 g of adipic acid, 166 g of isophthalic acid, and 199 g of terephthalic acid. It heated up to 240 degreeC, stirring. The condensation reaction was performed for about 7-8 hours to obtain a thermosetting polyester resin having a hydroxyl value of 19, an acid value of 1, and a viscosity (Gardner) of V.

Example 4

A 2-liter four-necked flask was equipped with a thermometer, condenser, stirrer and condenser and a temperature raising device was attached. Here, a glycol mixture containing 257 g of neopentyl glycol, 50 g of methyl propanediol, and 42 g of 1,6-hexanediol and a diacid mixture containing 71 g of adipic acid, 240 g of isophthalic acid, and 240 g of terephthalic acid were added thereto, and then slowly stirred. It heated up to 240 degreeC. Thereafter, a condensation reaction was performed for about 7-8 hours to obtain a thermosetting polyester resin having a hydroxyl value of 21, an acid value of 4, and a viscosity (Gardner) of Z3.

Example 5

A 2-liter four-necked flask was equipped with a thermometer, condenser, stirrer and condenser and a temperature raising device was attached. A glycol mixture containing 300 g of neopentyl glycol and 50 g of mixed cyclohexanedimethylol and a diacid mixture containing 40 g of adipic acid and 480 g of isophthalic acid were added thereto, and then the temperature was raised to 240 ° C. while slowly stirring. Thereafter, a condensation reaction was performed for about 7-8 hours to obtain a thermosetting polyester resin having a hydroxyl value of 19, an acid value of 4, and a viscosity (Gardner) of Z2.

Example 6

A 2-liter four-necked flask was equipped with a thermometer, condenser, stirrer and condenser and a temperature raising device was attached. Here, a glycol mixture containing 257 g of neopentyl glycol, 40 g of mixed cyclohexanedimethylol, and 50 g of 1,6-hexanediol and a diacid mixture containing 71 g of adipic acid, 240 g of isophthalic acid and 240 g of terephthalic acid were added thereto. It heated up to 240 degreeC, stirring slowly. Thereafter, a condensation reaction was performed for about 7-8 hours to obtain a thermosetting polyester resin having a hydroxyl value of 21, an acid value of 2, and a viscosity (Gardner) of Z2.

Comparative Example 1

A 2-liter four-necked flask was equipped with a thermometer, condenser, stirrer and condenser and a temperature raising device was attached. A glycol mixture containing 300 g of neopentyl glycol and 50 g of cyclohexanedimethylol was added thereto, and a diacid mixture containing 40 g of adipic acid and 480 g of isophthalic acid was added thereto, and the temperature was raised to 240 ° C. while gradually stirring. Thereafter, a condensation reaction was performed for about 7-8 hours to obtain a thermosetting polyester resin having a hydroxyl value of 19, an acid value of 4, and a viscosity (Gardner) of Z.

Synthesis Examples 1 to 6 and Comparative Synthesis Examples

Synthesis Examples 1 to 6 and Comparative Synthesis by applying the compositions shown in Table 1, respectively, in order to find out the characteristics of the coating of the PCM paint for coating including the polyester resin obtained in Examples 1 to 6 and Comparative Example 1, respectively PCM paint coating material of Example 1 was prepared.

Synthesis Example 1 Synthesis Example 2 Synthesis Example 3 Synthesis Example 4 Synthesis Example 5 Synthesis Example 6 Comparative Synthesis Example Resin of Example (1) 300 (g) Resin of Example (2) 300 (g) Resin of Example (3) 300 (g) Resin of Example (4) 300 (g) Resin of Example (5) 300 (g) Resin of Example (6) 300 (g) Resin of Comparative Example (1) 300 (g) Titanium Oxide (TiO ₂ ) 100 g 100 g 100 g 100 g 100 g 100 g 100 g Strontium chromium 100 g 100 g 100 g 100 g 100 g 100 g 100 g Dispersant 2 (g) 2 (g) 2 (g) 2 (g) 2 (g) 2 (g) 2 (g) Melamine curing agent 30 (g) 30 (g) 30 (g) 30 (g) 30 (g) 30 (g) 30 (g) Acid catalyst 3 (g) 3 (g) 3 (g) 3 (g) 3 (g) 3 (g) 3 (g) Antifoam 5 (g) 5 (g) 5 (g) 5 (g) 5 (g) 5 (g) 5 (g) solvent 460 g 460 g 460 g 460 g 460 g 460 g 460 g system 1000 g 1000 g 1000 g 1000 g 1000 g 1000 g 1000 g

As melamine curing agent, Cymel-325 (Cymel-325, manufactured by Cytec industry) was used, and as a solvent, Cocosol-100 (K-100), Cocosol-150 (K-150), cyclohexanone, xylene, and cello A mixed solution of sorb acetate was used.

Coating Film Evaluation of PCM Undercoat Paint Containing Polyester Resin

In order to examine the characteristics of the coating material comprising the polyester resin shown in Table 1, the coating material for each coat prepared in Synthesis Examples 1 to 6 and Comparative Synthesis Examples was applied to the substrate to form a coating film. The test was performed to evaluate the properties of the coating by coating. The results are shown in Table 2.

At this time, zinc phosphate-treated steel plate was used, and the thickness of the coating film was 5 ± 2㎛, and the surface temperature of the paper was 240 ℃. The top coating was a hydroxyl value of 0.5 to 1%, and a molecular weight of 12,000. , PCM coating material prepared using a thermosetting resin having a Tg of 30 ° C. was used.

Synthesis Example 1 Synthesis Example 2 Synthesis Example 3 Synthesis Example 4 Synthesis Example 5 Synthesis Example 6 Comparative Synthesis Example Polished (60 °) 90 91 92 90 92 92 91 MEK rubbing 100 or more 100 or more 100 or more 100 or more 100 or more 100 or more 100 or more Machinability 2T 2T- 2T- 2T 3T 3T 2T Pencil hardness F F 1H H H H H Adhesion 95/100 95/100 95/100 90/100 100/100 100/100 100/100 Acid resistance Good Good Good Good Good Good Good Alkali resistance Good Good Good Good Good Good Good Moisture resistance O O O O ◎ ◎ O Body, top adhesiveness O O O △ ◎ ◎ O

In Table 2, each evaluation item indicating the adhesion to the base and top coat is as follows. (Double-circle): Very good, O: Good, (triangle | delta): Normal, x: It means poor.

1. gloss; It was measured by ASTM-D-523 (a standard for measuring the gloss reflected by non-metallic materials determined by the American Society for Testing and Materials).

2. MEK Rubbing property; Measurement was made by NCCA-II-18 (evaluation specification for solvent resistance as determined by the National Coil Coaters Association).

3. Machinability; Measurement was made by NCCA-II-19 ("T" band test method as defined by the National Coil Coaters Association).

4. pencil hardness; Measurement was made by NCCA-II-12 (relative pencil hardness evaluation specification set by the National Coil Coaters Association).

5. Adhesion (C.E.T); The measurement was carried out by NCCA-II-20 (Possessing adhesion test method as defined by the National Coil Coaters Association).

6. Acid and alkali resistance; It was measured by ASTM-D-1308 (International Standard for Household Chemicals Used on Finishes of Organic Substances as defined by the American Society for Testing and Materials).

7. moisture resistance; After coating the formed film in 80 ℃ boiling water, it was performed by visually discriminating the state of the changed film after 20 days.

8. adhesion to body and top; By using a coin to scratch the coating film with the same force, it was performed by visually discriminating the degree of the coating film falling off the base and top coat.

Referring to Table 2, the coating film formed by using the coating material containing the thermosetting polyester resin of the embodiments of the present invention exhibited the same characteristics in the first half with respect to the coating film made of the coating material of Comparative Synthesis Example.

In particular, the paints of Synthesis Examples 5 and 6 comprising the thermosetting polyester resins of Examples 5 and 6 made of mixed cyclohexanedimethylol had better adhesion to base materials and tops than those of Synthesis Examples 1 to 4 and Comparative Synthesis Example 1. It can be seen that the excellent workability and properties.

As described above, according to the present invention, a condensation reaction of a diacid mixture with a glycol mixture comprising a first glycol and a second glycol mixed with 1,3-cyclohexanedimethanol and 1,4-cyclohexanedimethanol results in thermosetting polyester. Resin can be manufactured.

The polyester resin prepared by the above method is applied to produce a PCM coating material for excellent adhesion to the base and top coat, workability after painting, moisture resistance. In addition, the PCM paint coating material containing the thermosetting polyester can increase the compatibility with the solvent while maintaining excellent mechanical and chemical properties can form a stable coating film.

As described above, although described with reference to a preferred embodiment of the present invention, those skilled in the art will be variously modified without departing from the spirit and scope of the invention described in the claims below. And can be changed.

Claims (14)

A glycol mixture comprising 5 to 40% of a first glycol and 60 to 95% of a second glycol mixed with 1,3-cyclohexanedimethanol and 1,4-cyclohexanedimethanol relative to the total equivalent glycol; And a diacid mixture comprising an aromatic acid, aliphatic acid or a mixture thereof in a polyester resin for PCM paint, wherein the diacid mixture is condensed at a ratio of 1.0: 1.0 to 1.1. According to claim 1, wherein the first glycol is characterized in that 1,3-cyclohexanedimethanol having the formula (1) and the following formula (2) 1,4-cyclohexanedimethanol are mixed in a 1: 1 ratio Polyester resin for PCM coating to be.

------(One)

------(2) The method of claim 1, wherein the second glycol is cyclohexanedimethanol, ethylene glycol, propylene glycol, methylpropanediol, neopentyl glycol, 1,4-cyclohexanedimethylol, 1,6-hexanediol, ethylene oxide addition bisphenol Polyester resin for PCM paint, characterized in that it comprises at least one selected from the group consisting of a. The polyester resin of claim 1, wherein the aromatic acid comprises at least one selected from the group consisting of phthalic anhydride, tetrahydro phthalic anhydride, isophthalic acid and terephthalic acid. The polyester resin of claim 1, wherein the aliphatic acid comprises at least one selected from the group consisting of sebacic acid, adipic acid, and azelaic acid. The polyester resin of claim 1, wherein the aromatic acid comprises 50 to 100% of the total amount of diacids, and the aliphatic acid comprises 0 to 50% of the total amount of diacids. . The method of claim 1, wherein the polyester resin for PCM paint has a hydroxy value of 19 to 21, an acid value of 5 or less, Gardner viscosity of Z-Z3, the average molecular weight of 10,000 to 35000 for PCM paints Polyester resin. Forming a glycol mixture comprising 5-40% of a first glycol and 60-95% of a second glycol mixed with 1,3-cyclohexanedimethanol and 1,4-cyclohexanedimethanol relative to the total glycol equivalents; Forming a diacid mixture comprising an aromatic acid, aliphatic acid or a mixture thereof; And Condensation reaction of the glycol mixture and the diacid mixture in a ratio of 1.0: 1.0 to 1.1 equivalents to form a thermosetting polyester resin polyester resin for PCM paint. The method of claim 8, wherein the first glycol is formed by mixing 1,3-cyclohexanedimethanol having the following formula (1) and 1,4-cyclohexanedimethanol of the following formula (2) in a 1: 1 ratio. Method for producing a polyester resin for PCM paint, characterized in that. The method of claim 8, wherein the second glycol is cyclohexanedimethanol, ethylene glycol, propylene glycol, methylpropanediol, neopentyl glycol, 1,4-cyclohexanedimethylol, 1,6-hexanediol, ethylene oxide addition bisphenol Method for producing a polyester resin for PCM paint, characterized in that it comprises at least one selected from the group consisting of a. The method of claim 8, wherein the aromatic acid is phthalic anhydride, tetrahydro phthalic anhydride, isophthalic acid, terephthalic acid, at least one selected from the group consisting of polyester resin for PCM paint production Way. The method of claim 8, wherein the aliphatic acid comprises at least one selected from the group consisting of sebacic acid, adipic acid, and azelic acid. The method of claim 8, wherein the aromatic acid comprises 50 to 100% of the total amount of diacids, the aliphatic acid comprises a polyester resin for PCM coating, characterized in that it comprises 0 to 50% of the total amount of diacids. Way. The method of claim 9, wherein the polyester resin for PCM paint has a hydroxy value of 19 to 21, an acid value of 5 or less, Gardner viscosity of Z-Z3, the average molecular weight of 10,000 to 35000 for PCM paints Polyester resin manufacturing method.