KR20180103511A - Coating composition for cationic electrodeposition - Google Patents

Abstract

The present invention relates to a cationic electrodeposition resin composition used in an electrodeposition coating process. The cationic electrodeposition resin composition has excellent dispersibility and storage stability by containing a specific epoxy resin and a curing agent.

Description

TECHNICAL FIELD [0001] The present invention relates to a cationic electrodeposition resin composition,

The present invention relates to a cationic electrodeposition resin composition used for electrodeposition coating.

Generally, the cationic electrodeposition coating includes a composition including a resin into which a positive charge of an amine salt, an ammonium salt, or a sulfonium salt is introduced, and a process of applying a current to the conductor to deposit a positive charged resin and precipitate on the conductor To form a coating film.

Epoxy resin is mainly used as a resin included in the composition. However, the coating film formed of the composition containing the epoxy resin has a good anti-corrosive property and adhesion property, but has a problem of smoothness and flexibility and peeling off the coating film formed on the surface of the conductor.

On the other hand, a polyisocyanate compound blocked with a curing agent is used in the composition. However, the polyisocyanate compound The dispersibility of the epoxy resin and the storage stability of the composition are deteriorated and the physical properties of the coating film are deteriorated.

Korean Patent Publication No. 2007-0108943

Disclosed is a cationic electrodeposition resin composition which is capable of forming a coating film excellent in rustproofing property, adhesion property, workability and the like, and excellent in dispersibility and storage stability.

The present invention relates to an epoxy resin obtained by reacting a reaction product of a first epoxy compound, a triamine compound, and a sulfite compound with a second epoxy compound and a chain extended epoxy compound, a third epoxy compound and an amine compound, There is provided a cationic electrodeposition resin composition comprising a curing agent, a neutralizing agent and a solvent.

The first epoxy compound may be a compound represented by the following general formula (1).

[Chemical Formula 1]

The second epoxy compound and the third epoxy compound may be represented by the following formula (2).

(2)

In Formula 2, m is an integer of 0 to 6.

The triamine compound may be at least one selected from the group consisting of diethylene triamine, dipropylene triamine, and bishexamethylene triamine.

The sulfite-based compound may be a compound represented by the following formula (3).

(3)

HS- (C ₂ H ₄ -O-CH ₂ -OC ₂ H ₄ -SS) _n -C ₂ H ₄ -O-CH ₂ -OC ₂ H ₄ -SH

In Formula 3, n is an integer of 0 to 50.

The curing agent may be a reaction product of an alcohol compound, a polyisocyanate compound, and a reaction promoter.

The alcohol compound may be at least one selected from the group consisting of 2- (2-butoxyethoxy) ethanol, caprolactone, ethanol, butyl carbitol, butyl cellosolve, ethylene glycol, 1,2- propylene glycol, Glycol, polycaprolactone diol, 1,5-pentanediol, 1,2-butanediol, 1,2-hexanediol, trimethylol propane, polycaprolactone triol and 1,2,4- It may be at least one selected.

The reaction promoter may be at least one member selected from the group consisting of dibutyl tin dilaurate, dibutyl tin diacetate, dibutyl tin dimethoxide, dibutyl tin dibenzoate, and dibutyl tin oxide.

The cationic electrodeposition resin composition of the present invention may further comprise additives.

The cationic electrodeposition resin composition of the present invention comprises 25 to 35 parts by weight of the epoxy resin, 10 to 20 parts by weight of the curing agent, 0.5 to 1 part by weight of the neutralizing agent, 55 to 60 parts by weight of the solvent and 1 to 5 parts by weight of the additive .

The cationic electrodeposition resin composition of the present invention is excellent in dispersibility, line workability, and storage stability as it contains a specific epoxy resin and a curing agent. When a coating film is formed of the cationic electrodeposition resin composition, a coating film excellent in rust resistance, adhesion property, flexibility, hardness and the like can be formed.

Hereinafter, the present invention will be described.

The cationic electrodeposition resin composition of the present invention comprises an epoxy resin, a curing agent, a neutralizing agent and a solvent.

Epoxy resin

The epoxy resin contained in the cationic electrodeposition resin composition of the present invention plays a role of enhancing the rust resistance, adhesion and flexibility of the coating film. Specifically, the epoxy resin is a first epoxy compound (a _11), triamine compounds (a ₁₂₎ and sulfite-based compound reaction product of (a ₁₃₎ (a ₁₎ and a second epoxy compound (a ₂₎ reacting (A);

A third epoxy compound (b); And

Or an epoxy resin (a + b + c reactant) obtained by reacting an amine compound (c). The cation epoxy main chain resin can be obtained by reacting the first epoxy compound (a ₁₁ ) and the second epoxy compound (a ₂ ). At this time, the weight average molecular weight of the obtained cationic epoxy main chain resin may be 180 to 2,000, specifically, 180 to 1,000. When the weight average molecular weight of the cationic epoxy main chain resin is less than 180, the rust resistance and flexibility of the coating film may be deteriorated. When the weight average molecular weight is more than 2,000, the viscosity of the cationic electrodeposition resin composition may be increased and the workability may be deteriorated.

Specifically, the first epoxy compound (a ₁₁₎ may be a compound represented by the following general formula (1).

[Chemical Formula 1]

The second epoxy compound (a ₂ ) and the third epoxy compound (b) may be compounds represented by the following formula (2).

(2)

In Formula 2, m is an integer of 0 to 6.

The triamine compound (a ₁₂ ) and the sulfite compound (a ₁₃ ) serve to extend the chain of the cationic epoxy main chain resin.

The triamine compound (a ₁₂ ) may be at least one selected from the group consisting of diethylene triamine, dipropylene triamine, and bishexamethylene triamine. When the epoxy resin is prepared by using the triamine compound, the degree of saturation (unit: MEQ) of the base resin of the main chain resin is increased and the uniforming power of the coating film can be increased.

The sulfite compound (a ₁₃₎ may be of 150 to 8,500 weight average molecular weight, specifically, may be from 500 to 2,000. If the weight average molecular weight of the sulfite compound (a ₁₃ ) is less than 150, the chipping resistance and mechanical properties may deteriorate due to the decrease in flexibility of the coating film. If the weight average molecular weight exceeds 8,500, Gelling may occur during the curing reaction or storage of the curing agent.

Specifically, the sulfite compound (a ₁₃ ) may be a compound represented by the following formula (3).

(3)

HS- (C ₂ H ₄ -O-CH ₂ -OC ₂ H ₄ -SS) _n -C ₂ H ₄ -O-CH ₂ -OC ₂ H ₄ -SH

In Formula 3, n is an integer of 0 to 50.

The amine compound (c) mediates the polymerization reaction between the chain extending epoxy compound (a) and the third epoxy compound (b). The amine compound (c) may be at least one selected from the group consisting of diethanol amine, N-methylethanolamine, dimethylamino propylamine, diethylamino propylamine and diethanolaminopropyl Diethanolamine propylamine, and the like. In this case, when a primary amine and a secondary amine are mixed, excessive use of a primary amine may cause gelation in the course of the reaction, so the mixing ratio should be appropriately controlled.

The ratio (a: b: c) of each component in reacting the chain extending epoxy compound (a), the third epoxy compound (b) and the amine compound (c) is 5 to 10: : 1 to 2 by weight. If the ratio is out of the above range, gelation may occur or molecular weight may be increased during the reaction, resulting in poor water dispersibility, which may lower the storage stability of the cationic electrodeposition resin composition.

On the other hand, the reaction of the chain extending epoxy compound (a), the third epoxy compound (b) and the amine compound (c) may be carried out in a conventional organic solvent (for example, ethoxy ethanol, methoxy ethanol, Butoxyethanol, tequanol, etc.).

The content of the epoxy resin may be 25 to 35 parts by weight based on 100 parts by weight of the cationic electrodeposition resin composition. When the content of the epoxy resin is less than 25 parts by weight, the anticorrosiveness, adhesion and flexibility of the coating film may be deteriorated. When the content of the epoxy resin is more than 35 parts by weight, the flexibility of the coating film may be lowered or the curing density may be lowered, have.

Hardener

The curing agent contained in the cationic electrodeposition resin composition of the present invention reacts with a functional group (for example, a hydroxy group) contained in the epoxy resin to form a cured coating film. Such a curing agent may be a reaction product (d) of an alcohol compound (d ₁ ), a polyisocyanate compound (d ₂ ) and a reaction accelerator (d ₃ ).

The alcohol compound (d ₁₎ is able to block the reactivity of the isocyanate group contained in the polyisocyanate compound (d ₂₎ reacts with the polyisocyanate compound than in a constant temperature (d _2). The reaction product (d) in which the reactivity of the isocyanate group is blocked is not reacted with the functional group contained in the epoxy resin at 100 ° C or lower, and is cured in the oven after the coating. The blocked reaction product (d) The isocyanate group is activated and the activated isocyanate group reacts with the functional group contained in the epoxy resin to cause crosslinking to form a coating film.

The alcohol compound (d ₁ ) may be at least _{one selected from the} group consisting of 2- (2-butoxyethoxy) ethanol, caprolactone, ethanol, butyl carbitol, butyl cellosolve, ethylene glycol, Glycol, neopentyl glycol, polycaprolactone diol, 1,5-pentanediol, 1,2-butanediol, 1,2-hexanediol, trimethylol propane, polycaprolactone triol and 1,2,4- And the like.

Specifically, the alcohol compound (d ₁ ) may be butyl carbitol, trimethylol propane, or a mixture thereof. When a mixture of butyl carbitol and trimethylol propane is used as the alcohol compound (d ₁ ), the mixing ratio of the butyl carbitol and the trimethylol propane is preferably 1 : 0.1 to 0.3.

The polyisocyanate compound (d ₂₎ is 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, p- phenylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane -4,4 Diisocyanate, isophorone diisocyanate, diphenylmethane-4,4'-diisocyanate, triphenylmethane-4,4 ', 4 "-triisocyanate, or polymethylene polyphenyl isocyanate, Can be mixed.

The reaction accelerator (d ₃ ) may be at least one member selected from the group consisting of dibutyl tin dilaurate, dibutyl tin diacetate, dibutyl tin dimethoxide, dibutyl tin dibenzoate, and dibutyl tin oxide.

The weight average molecular weight of the reaction product (d) obtained by reacting the alcohol compound (d ₁ ), the polyisocyanate compound (d ₂ ) and the reaction accelerator (d ₃ ) may be 1,000 to 8,000. When the weight average molecular weight of the reactant (d) is less than 1,000, the alcohol compound may fall off during the curing process and the thickness loss of the coating film may be large. When the reactant (d) is more than 8,000, The storage stability may be deteriorated.

The reaction of the alcohol compound (d ₁ ), the polyisocyanate compound (d ₂ ) and the reaction accelerator (d ₃ ) may be carried out in the presence of a conventional organic solvent.

The content of the curing agent may be 10 to 20 parts by weight based on 100 parts by weight of the cationic electrodeposition resin composition. If the content of the curing agent is less than 10 parts by weight, the curing reactivity for forming a coating film may be deteriorated. If the amount is more than 20 parts by weight, dispersibility and storage stability of the cationic electrodeposition resin composition may be deteriorated.

corrector

The neutralizing agent contained in the cationic electrodeposition resin composition of the present invention neutralizes the reaction between the epoxy resin and the curing agent. These neutralizing agents may be phosphoric acid, acetic acid, formic acid, lactic acid, or sulfamic acid, which may be used singly or in combination.

The amount of the neutralizing agent may be 0.5 to 1 part by weight based on 100 parts by weight of the cationic electrodeposition resin composition. If the amount of the neutralizing agent is less than 0.5 part by weight, the neutralization ratio may be low and water dispersibility and storage stability may be deteriorated. If the amount of the neutralizing agent is more than 1 part by weight, the neutralization ratio becomes excessively high, Redissolution problems can occur.

solvent

The solvent contained in the cationic electrodeposition resin composition of the present invention enhances the dispersibility and controls the viscosity of the cationic electrodeposition resin composition. Such a solvent may conventionally be a solvent (for example, deionized water) known in the art.

The content of such a solvent may be 55 to 60 parts by weight based on 100 parts by weight of the cationic electrodeposition resin composition. If the content of the solvent is less than 55 parts by weight, the physical properties of the initial coating film may be deteriorated. If the amount of the solvent exceeds 60 parts by weight, the storage stability of the cationic electrodeposition resin composition may be deteriorated.

The cationic electrodeposition resin composition of the present invention may further include an additive.

The additives further included in the cationic electrodeposition resin composition of the present invention serve to enhance the physical properties of the coating film. The additive may be a film control agent, a fluidizing agent, an anti-cratering agent, a defoaming agent, or an antimicrobial agent, and may be used alone or in combination. Such additives may be conventionally known components.

The content of the additive may be 1 to 5 parts by weight based on 100 parts by weight of the cationic electrodeposition resin composition. If the content of the additive is less than 1 part by weight, it may be difficult to obtain the effect of increasing the physical properties of the coating film. If the amount is more than 5 parts by weight, it may be used more than necessary, Can be lowered.

The cationic electrodeposition resin composition of the present invention according to the present invention comprises an epoxy resin obtained by reacting a chain extended epoxy compound, a third epoxy compound and an amine compound. Therefore, when a coating film is formed using the epoxy resin, the anti- And excellent line workability can be obtained, thereby ensuring the paint quality.

In addition, since the cationic electrodeposition resin composition of the present invention contains a polyisocyanate compound having a controlled molecular weight due to reaction with an alcohol compound as a curing agent, the dispersibility and the storage stability during storage of the cationic electrodeposition resin composition .

Accordingly, the cationic electrodeposition resin composition of the present invention can be usefully used as an anticorrosive coating agent in electrodeposition coating of a conductor (for example, automobile body or automobile parts).

Hereinafter, the present invention will be described in detail with reference to examples. However, the following examples are illustrative of the present invention, and the present invention is not limited by the following examples.

[ Preparation Example  1] Epoxy resin production

A reaction product in which diethylenetriamine and polysulfide (Akzo nobel, THIOKOL LP-3) were reacted with glycidyl neodecanoic acid epoxy compound was reacted with an epoxy compound (KODO CHEMICAL, YD-128) to obtain a chain extended epoxy compound.

Next, 275 g of the epoxy compound (KCC, YD-011 (epoxy equivalent: 475)), 285 g of the chain extending epoxy compound, 72 g of an epoxy compound (Kukdo Chemical Co., YD-128 (epoxy equivalent: 187) 276 g was charged to a separate two-kettle lab reactor equipped with a mechanical stirrer, a condenser, a heater and a thermometer and heated to 80 占 폚.

Then, 42 g of diethanolamine, 21 g of dimethylaminopropylamine and 21 g of Texanol (Eastman) were added to the reactor, and the reaction was continued at 125 ° C. until the completion of the epoxy reaction. Methoxypropanol was recovered to obtain an epoxy resin Solid content: 74.5%).

[ Preparation Example  2] Preparation of hardener 1

2,000 g of 4,4'-methylene bis (phenyldiisocyanate) and 105 g of methyl isobutyl ketone were placed in a reactor equipped with a mechanical stirrer, a condenser and a thermometer, and the temperature was raised to 45 ° C. Next, 1,200 g of butyl carbitol was slowly added dropwise over 2 hours, 0.1 g of dibutyl tin dilaurate was added, and the isocyanate content was confirmed by maintaining and reacting. When the isocyanate content reached 10-11%, 250 g of trimethylolpropane and 250 g of butyl car 380 < / RTI > g of bitol was added. Then, the reactor was heated to 80 DEG C and the content of isocyanate was checked. When the content of isocyanate was 0.2% or less, the reaction was terminated. After completion of the reaction, 270 g of methoxypropanol and 320 g of texanol were added to the reaction mixture while cooling the reaction product to 80 ° C or lower by natural cooling method to obtain a curing agent resin (solid content: 80%).

[ Preparation Example  3] Preparation of hardener 2

484.7 g of 4,4'-methylene bis (phenyldiisocyanate) and 24.2 g of methyl isobutyl ketone were placed in a reactor equipped with a mechanical stirrer, a condenser and a thermometer, and the temperature was raised to 45 ° C. Next, 288.9 g of butyl cellosolve was gradually added dropwise over 2 hours while confirming the isocyanate content, and when the isocyanate content reached 5.0-5.5%, 74.5 g of trimethylolpropane was added. Then, the reactor was heated to 80 DEG C and held for 30 minutes, and then the isocyanate content was checked. When the content of the isocyanate was less than 0.2%, the reaction was terminated. After completion of the reaction, 127.7 g of methoxypropanol was added to the reaction mixture while cooling the reaction product to 80 ° C or lower by natural cooling method to obtain a curing agent resin (solid content 85% by weight).

[ Example  One]

The solvent of the epoxy resin was removed in the reactor 1, the hardening agent was introduced, and the epoxy resin from which the solvent of the reactor 1 was removed was dispersed while transferring the neutralizing agent and the ionized water in the reactor 2. At this time, in order to improve the water dispersion stability, the temperature was maintained at 40-50 ° C during water dispersion. After the water dispersion was completed, the secondary ionized water and the tertiary ionized water were sequentially added and mixed, and then an additive was added thereto. Thus, a cationic electrodeposition resin composition (solid content: 36%) was prepared through a filter. The composition of each component used in the preparation is shown in Table 1 below.

[ Example  2]

A cationic electrodeposition resin composition (solid content: 36% by weight) was prepared in the same manner as in Example 1 except that the composition of Table 1 was applied.

ingredient Example 1 Example 2 Epoxy resin The epoxy resin of Preparation Example 1 30.0 30.0 Solvent recovery Vacuum recovery -7.2 -7.2 Hardener The curing agent resin of Preparation Example 2 15.7 0 The curing agent resin of Preparation Example 3 0 15.7 corrector FORMIC ACID 0.6 0.6 water Primary deionized water 31.7 31.7 Secondary deionized water 23.0 23.0 additive Flowing agent DW-500
(KS Chemical) 1.4 1.4 Microgel Rheorol 200
(NanoCampton) 4.3 4.3 Polyester (Adipic acid + butyl carbitol) (KCC) 0.5 0.5 Total (parts by weight) 100 100

[ Experimental Example ]

The cationic electrodeposition resin compositions of Examples 1 to 2 were mixed with a pigment paste composition to prepare a mixture, electrostatically coated, and then baked at 160 ° C for 25 minutes in an oven to form a coating film having a uniform thickness. The physical properties of the formed film were evaluated by the following methods, and the results are shown in Table 2 below.

1. Polish

(1) Test instrument: gloss meter (can measure 20 ° and 60 ° gloss)

(2) Test method:

① Using a measuring device, measure the gloss of the specimen at an angle of incidence of 60 ° from the light source and a light receiving angle of 60 °.

② Change the measurement site and measure it three times. The average value is 60 ° mirror-polished.

(3) Judgment method: The specular glossiness should be 60 or more by 60 ° gloss method.

2. Roughness (Ra)

(1) Test instrument: illuminance meter

(2) Test method:

① CUT OFF Measure the specimen with a thickness of 20 ㎛ at 0.8 ㎜ and record the average value three times.

3. Impact resistance

(1) Test apparatus: DuPont impact tester

(2) Test method:

① Fix the specimen to the test machine.

② Impact the coating film surface with a DuPont impact tester (impact diameter: 12.7 ㎜, weight: 500 g, dropping distance: 50 ㎝ or more).

(3) Judgment method: When a shock is applied to the coated film surface, the falling distance and the weight of the weight which do not cause coating film defects such as crack and peeling are determined, and this value is taken as the impact resistance value of the coated film.

4. Flexibility

(1) Test apparatus: Constant temperature and humidity chamber, cutter knife, MANDRELL tester (diameter 10 mm)

(2) Test method:

① Place a blemish on the base with a cutter knife on the coating as shown in Fig. 5 at the center of the test piece.

② Place the mandrel test machine in the center parallel to the short side of the test specimen and bend the specimen to 180 ° within 1 second to check whether the coating is peeled off.

③ Repeat the above test after leaving the specimen in the constant temperature and humidity regulated at the specified wetting condition for the specified time.

(3) Judgment method:

(1) The degree of peeling from the base of the coated film at the bent portion is indicated according to the standard with respect to the portion with or without the cut.

② When displaying the degree of peeling, record the curvature of the bent part.

5. Curability

(1) Test apparatus: MIBK, ACETONE solvent, electrodeposition hardening test specimen (165 degree 25 minute cured specimen)

(2) Test method

① Wet the solvent on a cotton towel and rub the coated specimen with a certain pressure.

② Evaluate the same worker so that there is no error.

(3) Judging method: Record the number of round trips by rubbing until the paint film is damaged.

6. Antirust (salt water spraying)

(1) Test instrument: salt spray test machine (4), knife, cellophane adhesive tape

(2) Test method:

① Protect the cross section of the test specimen with a stable film even under the test conditions. (However, it is not necessary to protect the case when observing the corrosion situation from the end face).

② CROSS CUT the adjusted test specimen and attach it to the salt spray tester, and test continuously for the specified time.

- 10 탆: 800 Hr (CR, GA steel plate)

- 20 탆: 1,000 Hr (CR, GA steel plate)

③ Inspect the presence of corrosion products (non - lightening, rust, etc.) on the part other than 3 ㎜ on one side (6 ㎜ on both sides) from the cross - cut part.

④ After 1 hour, the cross-cut part is peeled off with a cellophane adhesive tape, and the presence or absence of peeling of the part other than 3 mm on one side is examined.

7. Storage stability

(1) Test instrument: turbidity meter

(2) Test method: Measure with a Hach Model 2100AN Ratio Recording Turbidimeter instrument.

(3) Judgment method: Record with NTU.

Item Example 1 Example 2 Remarks Exterior Gloss (60 ° Gloss) 77 75 The higher the measured value, the better the gloss Light intensity (Ra) 0.15 0.2 The lower the measured value, the smoother the better Mechanical properties /
Attachment Impact resistance 1kg × 50cm 1kg × 45cm The higher the measured value, the better Flexibility 8-9 mm 8-9 mm Hardenability
(MIBK Rubbing) More than 20 times More than 20 times Rustproofing
(Salt water spraying) 0.6 0.5 500 hours 0.9 0.8 1000 hours Storage stability
(Turbidity (NTU)) 90 95 The lower the measured value, the better

Referring to Table 2, it can be seen that the cationic electrodeposition resin composition of the present invention has excellent storage stability and formed a coating film having excellent physical properties.

Claims (10)

An epoxy resin obtained by reacting a chain extended epoxy compound, a third epoxy compound, and an amine compound obtained by reacting a reaction product of a first epoxy compound, a triamine compound, and a sulfite compound with a second epoxy compound;
Curing agent;
corrector; And
And a solvent. The method according to claim 1,
Wherein the first epoxy compound is a compound represented by the following formula (1).
[Chemical Formula 1]

The method according to claim 1,
Wherein the second epoxy compound and the third epoxy compound are compounds represented by the following formula (2).
(2)

In Formula 2, m is an integer of 0 to 6. The method according to claim 1,
Wherein the triamine compound is at least one selected from the group consisting of diethylene triamine, dipropylene triamine, and bishexamethylene triamine. The method according to claim 1,
Wherein the sulfite-based compound is a compound represented by the following formula (3).
(3)
HS- (C ₂ H ₄ -O-CH ₂ -OC ₂ H ₄ -SS) _n -C ₂ H ₄ -O-CH ₂ -OC ₂ H ₄ -SH
In Formula 3, n is an integer of 0 to 50. The method according to claim 1,
Wherein the curing agent is a reaction product of an alcohol compound, a polyisocyanate compound and a reaction promoter. The method of claim 6,
Wherein the alcoholic compound is at least one selected from the group consisting of 2- (2-butoxyethoxy) ethanol, caprolactone, ethanol, butyl carbitol, butyl cellosolve, ethylene glycol, 1,2-propylene glycol, Glycol, polycaprolactone diol, 1,5-pentanediol, 1,2-butanediol, 1,2-hexanediol, trimethylol propane, polycaprolactone triol and 1,2,4- Lt; RTI ID = 0.0 > 1 < / RTI > selected. The method of claim 6,
Wherein the reaction promoter is at least one selected from the group consisting of dibutyltin dilaurate, dibutyltin diacetate, dibutyltin dimethoxide, dibutyltin dibenzoate, and dibutyltin oxide. The method according to claim 1,
Wherein the cationic electrodeposition resin composition further comprises an additive. The method of claim 9,
25 to 35 parts by weight of the epoxy resin;
10 to 20 parts by weight of the curing agent;
0.5 to 1 part by weight of the neutralizing agent;
55 to 60 parts by weight of the solvent; And
And 1 to 5 parts by weight of the additive.