JPS6295357A - Composition for acrylic urethane coating material - Google Patents

Abstract

PURPOSE:The titled two-pack type composition, containing tin octylate in a specific acrylic polyol, having a long pot life in mixing a main agent with a curing agent, useful for low-temperature baking and drying and suitable for reparing vehicles, household appliances, etc. CONSTITUTION:A composition obtained by adding (B) 0.005-0.5pts.wt. tin content of tin octylate to (A) 100pts.wt. acrylic polyol having secondary hydroxyl groups in the side chain and 18-80 hydroxyl number, e.g. polymer of hydroxypropyl methacrylate, incorporating an organic solvent, e.g. ketonic solvent, catalyst, e.g. tertiary amine, etc., with the mixture to give a main agent and (C) incorporating a polyisocyanate, e.g. hexamethylene diisocyanate, as a curing agent with the main agent.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an acrylic urethane coating composition that forms a coating film through a crosslinking reaction between the hydroxyl groups of the acrylic polyol in the base agent and the isocyanate groups in the curing agent. More specifically, the present invention relates to an acrylic urethane coating composition that has a long pot life when mixing a base agent and a curing agent, and is useful for drying when baked at a low temperature of 120° C. or less.

The acrylic urethane coating composition of the present invention can be used in various fields such as plastics, vehicle repair, and home appliances.

[Conventional technology 1] Two-component acrylic urethane resin paints have urethane bonds in the coating film, and the coating film has excellent physical properties such as hardness, flexibility, abrasion resistance, and chemical resistance. Because of this, it is used in various fields. However, there is a problem in that after mixing the two liquids, the base agent and the curing agent, they gradually react even at air temperature, and the viscosity gradually increases, eventually making it impossible to coat. The time from the time of mixing until the paint becomes unpaintable is generally referred to as the pot life (hereinafter referred to as pot life), and from the viewpoint of reducing the troublesome preparation and loss of paint, a product with a long pot life is desired. However, there is a negative correlation between the pot life and the reaction rate of the coating film, and as the pot life becomes longer, the reaction rate decreases and curing takes longer and higher temperatures are required. If you try to do so, there is a problem that your life will be shortened. Various methods have been proposed to solve these problems.

For example, as seen in JP-A-59-226062, isocyanate groups are blocked with a blocking agent such as oxime, lactam, phenol, or tertiary alcohol,
Some people release the blocks by heating and react the hydroxyl groups and isocyanate groups of the polyol. In this method, the blocking agent (hardly dissociates) at room temperature, resulting in a pot life (long enough to be negligible);
Liquefaction is possible. This is a particularly preferred method because it reacts and hardens to a red color when heated.

Further, a method using a ketone solvent such as methyl ethyl chlorine or cyclohexanone as a solvent is also generally practiced. In this method, the ketone group associates with the hydroxyl group and the isocyanate group to mask each reactive group, resulting in an extremely long life in a solution state. And paint 1!
! This is a desirable method because when the ketone solvent evaporates, the mask is released and the curing reaction progresses.Furthermore, the monomer composition of the acrylic polyol is adjusted to lower the hydroxyl value and increase the glass transition point. There is a way to lower the reactivity by removing F.

[Problem to be Solved by the Invention 1] The above-mentioned conventional method does have a longer bottling life, but the method using a blocking agent generally requires a high temperature of 120'C or higher to dissociate the blocking agent. , 12
It is not practical if the reaction is carried out at a low temperature of 0'C or lower. Furthermore, even if a blocking agent that is saturated at low temperatures is used, there is a problem in that the pot life will not be extended. The /i method using ketone solvents has the disadvantage that they have a strong odor and strong dissolving power, so they corrode the painting hose or the object to be coated.Also, the acrylic polyol itself has to be adjusted. However, there was a problem in that the physical properties of the coating film deteriorated on the half surface.

Especially when the acrylic urethane coating film is baked at a low temperature, it appears to be hardened, but there is a considerable amount of unreacted area for a while immediately after baking.

As a result, thermal softening may occur. In order to solve these problems, methods using catalysts such as tertiary amines and metal salts have been conventionally used. For example, in a metal salt catalyst such as dibutyltin dilaurate, the isocyanate group coordinates to the metal and accelerates the reaction. However, this method has the problem of shortening the pot life.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide an acrylic urethane paint composition that has a long pot life, can be cured at a low temperature of 120°C or less, and has excellent immortality. Jru.

[Means for Solving the Problems 1] The acrylic urethane coating composition of the present invention uses a main agent containing an acrylic polyol as a main component and a curing agent containing a polyisocyanate as a main component, which are mixed at the time of use. 2 In the night-glowing acrylic urethane coating composition, the acrylic polyol has at least a secondary hydroxyl group in its side chain, the hydroxyl value of the secondary hydroxyl group is 18 to 8o, and the main ingredient contains The tin component of A-cuburic acid tin is O0o○5 to 10% by weight of acrylic polyol resin solid content.
It is characterized by containing 0.5 part by weight.

The acrylic urethane coating composition of the present invention is composed of a main agent containing an acrylic polyol as a main component and a curing agent containing a polyisocyanate as a main component.

The main ingredients include various organic solvents such as aromatic hydrocarbon solvents, aliphatic hydrocarbon solvents, ester solvents, and ketone solvents, metal salts, catalysts such as tertiary amines, various organic and inorganic pigments, and dyes. Alternatively, various commonly used paint formulations such as various scale additives can be selected and blended depending on the purpose.

One feature of the present invention lies in the composition of the acrylic polyol in the base ingredient.

Acrylic polyols are generally copolymers synthesized by radical solution polymerization, and are synthesized by selecting various types and amounts of monomers in consideration of desired physical properties. The present invention has one vJ characteristic in this monomer quaternary.

The acrylic polyol used in the acrylic urethane coating composition of the present invention has at least a secondary water M group in the side chain, and the hydroxyl value of the secondary hydroxyl group is 18 to 8.
It is 0. This secondary hydroxyl group is introduced by a monomer such as hydroxypropyl methacrylate (HPMA) or hydroxypropyl acrylate (HP△).

The water percentage of conventional acrylic polyols was generally introduced by means of 2-hydroxyethyl methacrylate (2-HE 1vlA) and was a primary hydroxyl group. The primary hydroxyl υ is highly reactive and causes a shortened life.3 The present inventors introduced a secondary hydroxyl group into the side chain of the acrylic polyol, and , composition of other monomers, type of polyisocyanate, catalyst F! As a result of extensive research into the n-type compounds, they discovered a composition with a long pot life and excellent curability, and completed the present invention.

The secondary hydroxyl group is the secondary hydroxyl y, water t by Mine.
riulil [i 18-80, good mat, < i, t
39-59 J: Sea urchin is introduced into the acrylic polyol.

If this is converted to HPM△monomer c1, HPMA monomer is about 5-20 (preferably 10-20) in all the monomers blended.
15) corresponds to 11%. hydroxyl 'rJ hlli is 18
If it is lower than 80, the crosslinking density of the coating film will be lowered by 1q, resulting in a decrease in the physical properties of the coating film, and if it is higher than 80, the hardness of the coating film will increase, but the adhesion to the object to be coated will decrease and the pot life will be shortened. Become.

Groups other than secondary hydroxyl groups in acrylic polyol 11
gB is a carboxyl group that acts as an internal catalyst, the first
A wide variety of functional groups such as hydroxyl groups and epoxy groups can be introduced in the same manner as in the past. Regarding the primary hydroxyl group,
It is necessary to introduce it so that the hydroxyl value is lower than about 13. If the value is higher than about 13, the pot life will be shortened. Note that this is less than about 3% of the total formulation in place of the 2-)-IEMA monomer.

In addition, by adjusting the blending amounts of hard monomers such as methyl methacrylate (MMA) and soft monomers such as 1lln-butyl acrylic, the glass transition point (Tg) is adjusted to 20°C.
It is preferable to set the temperature to 60°C.

As a result, an acrylic polyol 19 with excellent reactivity with polyisocyanates and physical properties of a cured film is obtained.

As in the past, the degree of polymerization of the acrylic polyol can be selected depending on the purpose. Generally, those having an ffl hanging average molecular weight of 15,000 to 40,000 are used.

Polyisocyanes 1 to 1 to be used as the curing agent include various polyisocyanates such as tolylene diisocyanate (KD+), xylylene diisocyanate (XDI), hexamethylene diisocyanate (+-IMDI>, and isoborone diisocyanate (IPDI)) as in the past. According to research conducted by the present inventors, it has become clear that the combination of the above-mentioned acrylic polyol with an aliphatic polyisocyanate such as HMDI is most desirable. With this combination, 120
This is because it cures at a low temperature of "C" or lower, has a good balance between pot life and curability, and has excellent weather resistance.

([3) The curing agent contains various types of stones, solvents,
Various additives and other ingredients can be added depending on the purpose. However, it is of course best to avoid materials that have hydroxyl groups that react with isocyanates, such as alcohols.

The blending ratio of acrylic polyol and polyisocyanate can be selected depending on the purpose, but in general, isocyanate m
It is desirable that the equivalent ratio (index) between (NC○) and hydroxyl group (○H) be around 1.0.

Another feature of the present invention is that tin octylate as a metal catalyst is blended in the main ingredient.

The inventors of the present invention have found that by using tin octylate in the resin system, the pot life is hardly affected and the non-tackiness is significantly improved.

Note that non-adhesiveness is a measure of the heat softening property of a paint film, and it is possible to apply a constant load to the paint film surface through gauze at a predetermined temperature, hold it for a predetermined time, and then remove the gauze from the paint film surface. It is measured by a test method that evaluates heat softening property by the trace of .

Tin octylate is blended so that the tin component is 0.005 to 0.510 parts per 100 parts of solid acrylic polyol. If the blending amount is less than 06OO5, the effect as a catalyst will not be as high as /υ, and 0.
．． If the number exceeds the 5Φ hanging part, the life of the bolt will be shortened.

The acrylic urethane paint composition of the present invention is prepared by adding other ingredients to adjust the main agent and curing agent in the same way as before, and after mixing, using a conventional method such as F-spray, roll coke, flow coater, etc. It can be painted using the painting method.

Then, it can be hardened at various temperatures from normal temperature drying to high temperature baking drying of 140° C. or higher. However, in order to take advantage of the features of the present invention, it is desirable to harden by baking and drying at a low temperature of about 70 to 100°C. This is because the curing speed is sufficiently fast and energy is saved.

[Operations and Effects of the Invention 1] According to the present invention, the reaction between the secondary hydroxyl group and the isocyanate group at room temperature is slowed down due to the steric hindrance of the #2 & hydroxyl group, and the life of the product can be extended. . Furthermore, heating after coating activates molecular movement, and the reactivity of secondary hydroxyl groups approaches that of primary water. As a result, if low-temperature baking drying is carried out at about 70° C. to 100° C., the secondary water-absorbing acid groups react with isocyanate groups in substantially the same manner as the primary hydroxyl groups, and a coating film that can be used for practical purposes is obtained. It is also clear that the reaction progresses gradually even after baking, but the fact that the reaction curve becomes gentle like this is surprising.
The internal stress of the coating film subjected to iQ becomes smaller, and the adhesion i′j property,
A coating film with excellent weather resistance etc. can be obtained.

Furthermore, the composition of the present invention has tin octylate in the base ingredient. This tin octylate exhibits its effects at an accelerated rate as its concentration increases. Therefore, when the tin octylate is diluted to the coating viscosity and the concentration of tin octylate is low, there is almost no catalyst.
It has little to no effect on pot life. After painting, the solvent evaporates and tin octylate! When i1 degree increases,
It exhibits a catalytic effect at an accelerated rate, and curing progresses. This improves tack-free properties. Furthermore, tin octylate has high temperature dependence and is particularly effective at temperatures above 60°C to 70°C, so low-temperature baking is a particularly useful catalyst for drying.

[Example] A more detailed explanation will be given below using specific examples.

(Example 1) (1) Synthesis of acrylic polyol As shown in Table 1, the acrylic monomers were 10 Wffi parts of hydroxypropyl methacrylate, 30 single-hung parts of styrene, 35 ffla parts of methacrylic methacrylate (M 1vlA), Blend 25 parts by weight of 1ln-butyl acrylic (B△), add 1.5Φ suspension of azobisisobutyronitrile as an initiator, add 40 parts by weight of toluene, 1 part by weight of butyl acetate, and 1 part by weight of xylene. In the flask containing N.
2 While maintaining the temperature at 105°C in a gas atmosphere, add the entire amount of the monomers listed in (g) dropwise for 2 hours or more, and then at 105°C.
The mixture was reacted for 6 hours to synthesize an acrylic polyol. The obtained acrylic polyol had a hydroxyl value of 39.1g43
℃, the small ffi average molecular weight is 25,000, and it is diluted to 50% non-volatile content.

(2) Preparation of paint Using the acrylic polyol prepared above, disperse titanium oxide powder in a non-demolition mill so that the amount is 50 parts per 50 parts of the solid content of the acrylic polyol. Furthermore, a white paint was prepared by blending the tin component of tin octylate in an amount of 0.05 parts by weight per 100 parts by weight of the solid content of the acrylic polyol. In addition, using the above acrylic polyol, aluminum paste (110
9M (manufactured by Toyo Aluminum Co., Ltd.) was blended with aluminum powder in an amount of 100 parts per 90 parts by weight of acrylic polyol solid content, and tin octylate was blended in the same amount as above to prepare a metallic paint.

For the above two types of paints, HMDI (Coronate E day, manufactured by Nippon Polyurethane Co., Ltd.) as a curing agent was added to NC○/○H=
1.0 parts by weight, 20 parts by weight of toluene, 20 parts by weight of butyl acetate, 2 parts of xylene, 20 parts by weight of ethyl acetate, 10 parts by weight of cellosolve acetate,
and Tsurpez 100 with a thinner consisting of 10 parts, the coating viscosity was 15 seconds (N 0 , 47 i -
It was diluted to 7.20'C).

(3) Measurement of pot life The two types of paints adjusted to a viscosity of 15 seconds as described above were kept in a sealed state at 40°C, taken out at regular intervals and painted with air spray. The point at which the surface smoothness deteriorated was measured and determined as the dry life. At the same time, the paint that has been diluted to the viscosity of 15 seconds above is heated at 40°C for 8 seconds.
An accelerated test was conducted in which the temperature was heated in a closed state for an hour, and the initial 15
The ratio of viscosity after the accelerated test to seconds was taken as the viscosity increase rate. The results are shown in Table 2.

(4) Painting: Two types of paints with a viscosity of 15 seconds diluted in Paint Adjustment 1 were applied with a ΦΦΦ coating on the cationic electrodeposition coating, and a 70 mm x 150 mm x 801 m area was soaked with water. Each steel plate of different sizes was coated with air spray to a film thickness of 35 to 401.L, and baked and dried at 80°C for 30 minutes.Furthermore, the seedlings were tested for 24 hours. The following tests were conducted using the sample as a piece.

(5)...Test The following test (the T-6 pencil hardness test was conducted for each of the 2 seconds of the white paint film and metallic paint film given 1!1 above, using a Mitsubishi Uni-Pencil, 45 The hardness was measured by scratching the paint film at an angle of 100 degrees.Adhesion was measured by making 100111 increments of 1 mm square on the paint film with a cutter knife, pressing cellophane tape on it, and peeling it off to determine if the paint film remained. Judgment was made by the number of squares.Water-resistant adhesion was determined by immersing a test piece in warm water at 40°C for 10 days, and then conducting the above-mentioned adhesion test.

The gloss was measured using a gloss meter at 6 billion gloss.

For 1-temperature resistance, a 1,200-hour accelerated weathering test is performed using a weather-o-meter, the subsequent gloss is measured, and the gloss retention rate relative to the initial gloss is calculated/ζ. At the same time, using a color difference meter (manufactured by Suga Test Instruments Co., Ltd.), ΔF according to Hunter's Lab1 was measured with respect to that before the weather resistance test. In addition, for permanent adhesion, place gauze on the surface of the paint film, and then
A 500g weight having a circular shape of m is placed, and 2
Holds time. After taking it out, the traces of gauze on the surface of the coating film were visually judged. In addition, ◎ means that there are almost no marks, and O means that one leather mark remains in dots.
△ means that a thin linear mark remains, but the gauze falls off the paint film due to its own weight, and X means that the gauze adheres to the paint film and will not come off unless it is peeled off by hand.

The results are shown in Table 2.

<Example 2) ○, medyl methacrylate in the monomer composition of Example 1
An acrylic polyol was synthesized in the same manner as in Example 1 except that bfffffi part was replaced with acrylic acid as tffi,
A paint was prepared in the same manner by adding the same amount of tin octylate, painted and dried in the same manner, pot life was measured in the same manner, and the same test was conducted.

The results are not shown in Table 2.

(Examples 3 to 4) Using the same acrylic polyol as in Example 2, the tin component of tin octylate was added in an amount of 0.01 part and 0.1 part, respectively, per 100 parts by weight of the solid content of the acrylic polyol. Except for the above, the paints were prepared in the same manner as in Example 1, the coating and drying were carried out in the same manner, the pot life was determined in the same manner as iml+, and the same tests were conducted. The results are shown in Table 2.

Comparative Examples 1 and 2) The paints were prepared in the same manner as in Example 1, and the coating and drying were carried out in the same manner, the pot life was measured in the same manner, and the same tests were conducted. The results are shown in Table 2.

(Comparative Examples 3 to 5) HPMA was 5.10.20 heavy parts, styrene was 15,000 parts, and MM△ was 54.5.
4, 5.39.5 parts by weight, and 0.39.5 parts by weight of acrylic acid, respectively.
An acrylic polyol was synthesized in the same manner as in Example 1, except that the amount was 1 part. The pot life was measured and a similar test was conducted. vJ results are not shown in Table 2.

(Conventional Examples 1 to 3) Comparative Examples 3 to 5 except that HPMA was not used and 2-l-l EMA was used in the 5, 10, and 20 city hanging parts, respectively.
Acrylic polyols were synthesized in the same manner as in Comparative Examples 3 to 5, paints were prepared, painted and dried in the same manner, pot life was measured in the same manner, and tests were conducted in the same manner. The results are shown in Table 2.

<Consolidation> From the comparison of Examples 1 to 4 and Comparative Examples 1 to 2, by blending tin octylate, the pot life was almost improved.
It is clear that the non-tackiness is improved, that is, the curability is improved, without any V shadow. Moreover, although Comparative Examples 3 to 5 have almost the same various physical properties of the coating films as Conventional Examples 1 to 3, they have a sufficiently long boiling life of 8 hours or more and a low viscosity increase rate. It is clear that this is due to the secondary hydroxyl group of HPMA.

Patent applicant Aisin Kako Co., Ltd. agent
Patent Attorney Hirodo Okawa Patent Attorney Akio Maruyama

Claims (3)

[Claims] (1) In a two-component acrylic urethane paint composition in which a base agent containing an acrylic polyol as a main component and a curing agent containing a polyisocyanate as a main component are mixed at the time of use, the acrylic polyol is added to the side chain. It has at least a secondary hydroxyl group, and the hydroxyl value of the secondary hydroxyl group is from 18 to
80, and the tin component of tin octylate is in the range of 0.005 to 0.80 parts by weight per 100 parts by weight of the acrylic polyol resin solid content.
5 parts by weight of an acrylic urethane paint composition. (2) The acrylic urethane coating composition according to claim 1, wherein the secondary hydroxyl group is a hydroxyl group of hydroxypropyl methacrylate in the acrylic polyol main chain. (3) The acrylic urethane coating composition according to claim 1, wherein the polyisocyanate is an aliphatic polyisocyanate.