JP2001279172A - Mat surface coating film composition for in-mole coating - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a mat surface coating film composition for in-mold coating having a high profile mat surface feeling and soft and wet touch, capable of keeping the mat surface for a long time without dropping a mat surface minute powder agent, and capable of uniformly copying the coating film without retaining a part of the coating film on the surface of a die. SOLUTION: This mat surface coating film composition for in-mold coating comprises a binder resin (A) comprising a polyester resin (a-1) containing a hydroxyl group and cured with a urethane and a polyurethane (a-2) containing a hydroxyl group, and a polyurethane resin minute powder (B) having a hydroxyl group value of not lower than 100 but not higher than 250. Because the polyurethane resin minute powder has a hydroxyl group, it forms a strong and consolidated coating film together with the binder. Thus, the coating film obtained shows no change with a lapse of time over a long period of time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an in-mold matte coating composition for transferring a coating film to a molded product by previously coating the molded product with a resin injection molding die. The present invention relates to an in-mold matte coating film composition which is excellent in abrasion resistance and can provide a coating film having a high-grade matte feeling and a soft touch.

[0002]

2. Description of the Related Art Interior parts such as a steering wheel of an automobile must not only be integrally formed into a complicated shape, but also have a matte feeling such as velvety, soft and soft. A luxurious feeling such as a moist touch is required. Conventionally, in order to impart such a high-grade design feeling, using a coating composition to which a matte fine powder has been added, a molded product base resin injection molding die is preliminarily painted, and a polyurethane resin or the like is applied thereto. 2. Description of the Related Art In-mold coating is performed in which a coating film is transferred onto a surface of a molded product by injecting a resin.

[0003] Conventionally, matting fine powders include silica,
Silicon earth, alumina, calcium carbonate, magnesium carbonate, fine powder of acrylic resin, etc., especially silica-based are often used, such fine powder is dispersed in binder resin such as acrylic resin, polyurethane resin, polyester resin and the like. Was used.

However, these fine powders do not have a functional group that can be integrated with the binder resin and are merely held in a mechanically bonded state, so that they lack a sense of quality and soft touch. In addition, there is a drawback that the matte fine powder drops off due to friction and abrasion of the painted surface, and the gloss increases. Also, in order to transfer the coating film to the molded product, there are many defective products where a part of the paint and the matting fine powder remain when releasing from the mold,
There is a problem that the yield is poor.

The present invention has been made to solve the above problems, and has a high-grade matte feeling and a soft and moist touch, and does not cause the matte fine powder to fall off, and provides a matte surface. An object of the present invention is to provide a matte coating composition for in-mold coating that can be held for a long period of time and that can uniformly transfer a coating film without leaving a part of the coating film on a molding die surface. I do.

[0006]

In order to achieve the above object,
As a result of earnest study, the present inventors have used a hydroxyl group-containing polyurethane resin fine powder as a matte fine powder and an excellent matte feeling by using a mixture of a urethane-curable polyester resin and a polyurethane resin as a binder resin. The present inventors have found that a matte coating composition for in-mold coating, which has a tactile sensation, can maintain a matte state for a long period of time, and has good mold release properties, can be obtained.

That is, the matte coating composition for in-mold coating of the present invention comprises (A) a urethane-curable (a-1) hydroxyl-containing polyester resin and (a-2) a binder resin comprising a hydroxyl-containing polyurethane resin. And (B) a fine powder of a hydroxyl group-containing polyurethane resin.

Prior to use, the coating composition of the present invention contains a polyisocyanate compound as a curing agent. The hydroxyl group of the polyurethane resin fine powder reacts with the isocyanate group to form a strong and integral coating film together with the binder resin. Therefore, the coating film obtained by the present invention does not change over time for a long period of time.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [I] Matte coating composition for in-mold coating Hereinafter, components of the mat coating composition for in-mold coating of the present invention will be described in detail.

(A) Binder Resin In the coating composition of the present invention, (a-1) a hydroxyl group-containing polyester resin and (a-2) a hydroxyl group-containing polyurethane resin are used as the binder resin. Since the polyester resin and the polyurethane resin used in the present invention have at least two or more hydroxyl groups in a molecule, they react with a polyisocyanate compound as a curing agent and undergo urethane curing. 2 above
By using a mixture of different kinds of resins, it is possible to form a tough coating film that is soft and has high scratch resistance without leaving a part of the coating film on the surface of a molding die.

(A-1) Hydroxyl-Containing Polyester Resin The hydroxyl-containing polyester resin used in the present invention preferably has a number average molecular weight of 10,000 to 40,000, more preferably 15,000 to 40,000.
More preferably, it is 30,000. When the molecular weight is 10,000 or less, the oil and fat contamination is poor, and the formed coating film may become brittle. When the molecular weight is 40,000 or more, the flexibility decreases, which is not preferable.

The hydroxyl value of the hydroxyl group-containing polyester resin is preferably from 1 to 30, and more preferably from 1 to 10 (in terms of resin solid content). When the hydroxyl value is less than 1, chemical resistance becomes poor, and when the hydroxyl value exceeds 30, water resistance becomes poor, which is not preferable.

Such a polyester resin can be obtained by polycondensing (esterifying) a polyhydric alcohol with a polybasic acid or its anhydride. Polyhydric alcohols include ethylene glycol, diethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, neopentyl glycol, butanediol, 1,5-pentanediol, 1,6-hexanediol, and 1,4-cyclohexane Dimethanol, 2,2-dimethyl-3-hydroxypropyl-2,2-dimethyl-3-hydroxypropionate, 2,2,4-trimethyl-1,3-pentanediol, polytetramethylene ether glycol, polycaprolactone Polyols, glycerin, sorbitol, anisole, trimethylolpropane, trimethylolbutane, hexanetriol, pentaerythritol, dipentaerythritol, and their multimers (dimers, octamers, etc.) and the like. It can be used in combination Le two or more.

The polybasic acid or anhydride thereof includes phthalic acid, phthalic anhydride, tetrahydrophthalic acid, tetrahydrophthalic anhydride, hexahydrophthalic acid, hexahydrophthalic anhydride, methyltetrahydrophthalic acid, methyltetrahydrophthalic anhydride, Hymic acid anhydride, trimellitonic acid, trimellititic anhydride, pyromellitotic acid,
Pyromellitotic anhydride, isophthalic acid, terephthalic acid,
Maleic acid, maleic anhydride, fumaric acid, itaconic acid,
Examples include adipic acid, azelaic acid, sebacic acid, succinic acid, succinic anhydride, dodecenylsuccinic acid, dodecenylsuccinic anhydride, and the like, and two or more of these can be used in combination.

(A-2) Hydroxyl group-containing polyurethane resin The hydroxyl group-containing polyurethane resin has a number average molecular weight of 5,000 to 6
Preferably, the number average molecular weight is 10,000 to 50,000.
More preferably, 000. If the molecular weight is 5,000 or less, the coating becomes brittle, if the molecular weight is 60,000 or more,
It is not preferable because flexibility is reduced.

The hydroxyl value of the hydroxyl group-containing polyurethane resin is preferably from 70 to 180, and the hydroxyl value is preferably from 100 to 180.
It is more preferably 150 (in terms of resin solid content). When the hydroxyl value is 70 or less, chemical resistance becomes poor, and when the hydroxyl value is 180 or more, water resistance becomes poor, which is not preferable.

Such a hydroxyl-containing polyurethane resin is obtained as a reaction product of a polyol and a polyisocyanate. Here, examples of the polyol include a polyester polyol, a polyether polyol, and a polycarbonate polyol.

The polyester polyol is the above-mentioned (a-1)
As a reaction product of one or more of the polyhydric alcohols and the one or more of the polybasic acids or anhydrides thereof.

The polyether polyol is used in the above (a-1)
Is a product obtained by addition-polymerizing one or more of the polyhydric alcohols represented by the formula (1) with an alkylene oxide such as ethylene oxide, propylene oxide, butylene oxide, or styrene oxide.

The polycarbonate polyol may be used in combination with one or more of the polyhydric alcohols described in (a-1) above and a compound having a carbonate group such as ethylene carbonate, dimethyl carbonate, diethyl carbonate and diphenyl carbonate. Is obtained as a reaction product.

On the other hand, examples of the polyisocyanate include organic diisocyanates such as hexamethylene diisocyanate, metaxylene diisocyanate, tolylene diisocyanate, isophorone diisocyanate, 4,4'-methylenebis (cyclohexyl isocyanate) and dimer acid diisocyanate; Reaction products with a dihydric alcohol.

As a method of reacting a polyol with a polyisocyanate to produce a polyurethane resin, a known method can be used. Considering the type of the reactants used and the desired degree of polymerization, etc. Selected as appropriate. In reacting the polyol with the polyisocyanate, it is possible to use one or more of the above-mentioned polyester polyols, polyether polyols and polycarbonate polyols as the polyol. In this reaction, it is possible to use a chain extender to increase the degree of polymerization of the produced polyurethane resin. Examples of the chain extender include low molecular weight diamines such as ethylenediamine, propylenediamine, isophoronediamine, cyclohexanediamine, 2,4,4-trimethylhexamethylenediamine, and xylylenediamine. Also, alkanolamines such as aminoethanol, aminoethoxyethanol and diethanolamine, monoamines such as ethylamine and butylamine, and the above-mentioned low molecular weight diols such as ethylene glycol can be used in combination with these low molecular weight diamines. Further, as a catalyst used when reacting a polyol and a polyisocyanate, a normal catalyst for a urethane-forming reaction can be used.Examples include dibutyltin dilaurate, dioctyltin dilaurate, stannasoctoate, and iron. Acetyl acetonate, triethylamine and the like can be mentioned.

Preferably, the polyurethane resin is used after being modified with acrylic. Since a large amount of hydroxyl groups can be introduced into the polyurethane resin by acrylic modification, the coating composition can be designed to be easily cured with urethane. In addition, it is possible to enhance the solubility in a solvent, and to form a coating film that is strong against scratching as well as antiglare.

For the acrylic modification, hydroxy group-containing (meth) acrylates such as hydroxymethyl (meth) acrylate, hydroxyethyl (meth) acrylate, hydroxybutyl (meth) acrylate and N-methylolacrylamide are used. Is preferred.

(A-3) Others A binder resin other than (a-1) and (a-2) may be used in combination as long as the physical properties of the coating film are not significantly impaired.
In this case, the mixing ratio of the other binder resin is not more than 50% (weight ratio) with respect to the entire binder resin.

(B) Fine polyurethane resin powder In the present invention, the fine polyurethane resin powder has a role as a matting agent. The hydroxyl group-containing polyurethane resin fine powder preferably has a hydroxyl value of 100 or more and 250 or less.
Since the hydroxyl group is urethane-bonded to the polyisocyanate compound as a curing agent, the polyurethane resin fine powder becomes a strong integral coating film together with the binder resin, so that the matte fine powder hardly falls off, and is excellent over a long period of time. The matte state is maintained.

The fine polyurethane resin powder has a hydroxyl value of 100
If the ratio is less than the above range, the bonding force due to the functional group is small, and the friction and wear resistance is undesirably reduced. Also, the hydroxyl value is
If it is 250 or more, the tackiness of the resin is increased, and the feeling is uncomfortable, which is not preferable. More preferably, the hydroxyl value is 150 to 200.

The fine polyurethane resin powder preferably has a glass transition point (Tg) of 0 to 30 ° C. If the Tg is 0 ° C or lower, the abrasion resistance is lowered, and if the Tg is 30 ° C or higher, the coating film has a hard touch feeling, which is not preferable.

The fine polyurethane resin powder has an average particle size of
It is preferably from 10 to 100 μm, more preferably from 20 to 70 μm. If the average particle diameter is 10μm or less, a sufficient matte feeling cannot be obtained, and if the average particle diameter is 100μm or more,
It is not preferable because the smoothness of the coating film is reduced.

Next, a method for producing such a polyurethane fine powder will be described. First, at least one aliphatic dibasic acid is reacted with at least one aliphatic dihydric alcohol to form a polyester polyol having a molecular weight of about 500 to 3,000. Examples of the aliphatic dibasic acid include malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, cornic acid, azelaic acid, sebacic acid and the like. As the aliphatic dihydric alcohol, ethylene glycol,
Examples thereof include diethylene glycol, propylene glycol, dipropylene glycol, and hexanediol.

Next, the polyester polyol is further subjected to a chain extension reaction using at least one of the above-mentioned aliphatic dihydric alcohols and at least one of the diisocyanate compounds, whereby a molecular weight of 4,000 to 40,000 is obtained.
Synthesize polyester urethane resin. Examples of the diisocyanate compound include xylene diisocyanate,
Examples thereof include diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, and tolylene diisocyanate.

Next, using a three-necked flask having a stirrer, a reflux condenser and a dropping funnel, the polyester urethane resin and the dispersing aid are heated together with a dispersion medium to about 70 to 90 ° C. while stirring. Disperses the polyester urethane resin and dissolves the dispersing aid. Further, a polyisocyanate, a reaction catalyst and a curing accelerator are added, and the mixture is reacted for 1 to 4 hours while maintaining the temperature at 70 to 90 ° C.
As a result, a suspension of a hydroxyl group-containing polyurethane resin fine powder having a particle diameter of 10 to 100 μm is obtained.

At this time, as the polyisocyanate that can be used, for example, hexamethylene diisocyanate (HM
DI) and other alicyclic polyisocyanates such as isophorone diisocyanate (IPDI), hydrogenated diphenyl diisocyanate, diphenylmethane-4,4'-diisocyanate (MDI), hydrogenated MDI
And the like.

[II] Method for Preparing the Matte Coating Film Composition for In-Mold Coating The (A) binder resin and the (B) polyurethane resin fine powder respectively prepared as described above were mixed with (A) +
(B) is mixed in a proportion of preferably 20 to 70 parts, more preferably 30 to 70 parts, and particularly preferably 40 to 60 parts with respect to 100 parts (weight of solid content). This mixing ratio also has a large effect on the properties of the coating film. If the ratio of (B) is less than 20 parts, a sufficient matte surface may not be formed.

The mixing ratio between the hydroxyl group-containing polyester resin (a-1) and the hydroxyl group-containing polyurethane resin ([a-2) + (B)] is 20:80 to 50:50 by weight. Preferably, there is. When the content of the polyester resin is 20% or less, the adhesion to the material is poor, and the flexibility of the formed coating film is poor.
It becomes a paint film with a hard image like a plastic molded plate. On the other hand, when it is 50% or more, the coating film becomes soft, and the coating film strength decreases.

[0036] If necessary, an extender pigment, a coloring pigment, a leveling agent, an antioxidant and the like may be added to the coating composition.

Thus, the constituent components are dissolved in the solvent to obtain a matte coating composition for in-mold coating. Usable solvents include ordinary organic solvents for coatings such as aliphatic hydrocarbon solvents, ester solvents, ketone solvents, ether solvents and the like.

[III] Method of Using Matte Coating Composition for In-Mold Coating The matte coating composition for in-mold coating of the present invention is added with a polyisocyanate compound as a curing agent prior to its use.

As the isocyanate compound, aliphatic polyisocyanate, alicyclic polyisocyanate, aromatic polyisocyanate and the like can be used.

The matte coating composition for in-mold coating of the present invention has a coating thickness of 10 to 100 μm by a predetermined coating method.
m, preferably 30 to 70 μm. As a coating method, a commonly used method can be selected, but preferable methods include an air spray method, an airless spray method, and a flow coater method. When the coating composition is dried, a polyurethane resin is injected and cured at about 120 ° C., whereby a high-grade coating film is integrally formed on the surface of the molded product.

[0041]

The present invention will be described below with reference to examples.
The present invention is not limited to these.

Examples 1 to 8 (I) Preparation of fine powder of hydroxyl group-containing polyurethane resin First, polyester polyol ("Desmophen 170
0 ", manufactured by Nippon Polyurethane Industry Co., Ltd.) 200 g and ethylene glycol 32 g are dissolved in xylene 1100 g, and dissolved at 80 ° C.
Heated for hours.

Next, 20 g of Colonnade HL (hexamethylene diisocyanate: manufactured by Nippon Polyurethane Industry Co., Ltd.)
To carry out a chain extension reaction to obtain a polyester polyurethane resin.

Next, using a three-necked flask having a stirrer, a reflux condenser and a dropping funnel, 130.5 g of the polyester urethane resin and an oil-modified alkyd resin (dispersed with coconut oil, oil length 40%) (phthalic kid
10.5 g of 133-60 (manufactured by Hitachi Chemical Co., Ltd.) is heated to about 85 ° C. together with 743.0 g of xylene as a dispersion medium. This disperses the polyester urethane resin and dissolves the oil-modified alkyd resin.

Next, Colonnade HL is used as an isocyanate.
(Hexamethylene diisocyanate: Nippon Polyurethane Industry Co., Ltd.) 68.5 g, zinc naphthenate as reaction catalyst
3.5 g (metal content 6%) and 12.Og of a 1% xylene solution of dibutyltin dilaurate as a curing accelerator were added, and 85
The reaction was carried out at 2 ° C. for 2 hours.

Thereafter, 35.0 g of propylene glycol monomethyl ether was added as a reaction terminator, and the mixture was maintained at 85 ° C. for 1 hour to remove unreacted isocyanate.
450 g suspension of polyurethane beads with a particle size of μm
I got

The suspension was filtered to obtain a fine powder of a hydroxyl group-containing polyurethane resin. The resulting polyurethane resin fine powder had a hydroxyl value of 180.

(II) Preparation of matte coating composition for in-mold coating A: Binder resin (a-1) Hydroxyl-containing polyester resin ("Desmophen 670", manufactured by Nippon Polyurethane Industry Co., Ltd.) (a-2) Acrylic-modified polyurethane resin (trade name "Polyurethane 6600", manufactured by Arakawa Chemical Industries, Ltd.)

B: Fine powder of hydroxyl group-containing polyurethane resin prepared with matting agent (I)

C: Multimer of curing agent hexamethylene diisocyanate (trade name “Duranate E-402-90T”, manufactured by Asahi Chemical Industry Co., Ltd.)

According to the composition shown in Table 1, A binder resin and B matting agent were mixed and dispersed in 60 parts by weight of xylene to prepare a coating composition, and a C curing agent was mixed immediately before coating.

[0052]

[Table 1]

(III) In-mold coating The above matte paint is applied to a mold so that the coating film thickness is about 30 to 70 μm, and then dried at 60 ° C. for 1 minute. The mold temperature was kept at 120 ° C. for about 2 minutes. After sufficient cooling, the mold was removed.
For all of the above, the coating film could be transferred uniformly without leaving a part of the coating film on the surface of the molding die. Further, the obtained coating film had a suede tone and a surface gloss value (60 ° gloss value) of 0.5 to 3.0.

(IV) Performance Evaluation (Abrasion Resistance) A test piece of 30 × 220 mm was sampled, attached to a Gakushin type friction tester type tester (JISL0849), and a white cotton cloth of each condition of a dry cloth and a sweat cloth was used. Put on the friction element and set the friction element load to 2N
(200 gf) rubbed 5000 times at a reciprocating speed of 30 times per minute between 100 mm on the test piece. The results are shown in Table 2.

[0055]

[Table 2]

(Chemical resistance) 4g / 100
Spread to a coating amount of about ² cm2,
After standing for an hour, it was heated in an atmosphere at 80 ° C. for 48 hours. Thereafter, the appearance when the temperature was returned to room temperature was evaluated. The results are shown in Table 3.

[0057]

[Table 3]

(Chemical abrasion resistance) A test piece having a width of about 30 mm and a length of 200 mm was attached to a test table of a friction tester II type defined in HSL0849, and a white cotton cloth (Kanakin No. 3) over the contact surface of the wear element and fix it. The load of the wear element is 2N (200gf) and the distance between 100mm on the test piece is 3 minutes per minute.
It reciprocated at the speed of reciprocating 0 times, and the degree of contamination of white cotton cloth and abrasion of the material were visually judged. The results are shown in Table 4.

[0059]

[Table 4]

[0060]

As described in detail above, the matte coating composition for in-mold coating of the present invention transfers a coating film uniformly without leaving a part of the coating film on the surface of a molding die. be able to. The resulting coating film has a high-grade matte feeling and a soft and moist touch, and can maintain the matte state for a long period of time, so that it can be suitably used for in-mold coating of automobile interior parts and the like.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Nobuyuki Takahashi 1-4-1, Chuo, Wako-shi, Saitama Prefecture Inside Honda R & D Co., Ltd. (72) Inventor Osamu Aoki 1-4-1, Chuo, Wako-shi, Saitama Inside Honda R & D Co., Ltd. Town Ohiradai 40 F term (reference) 4J038 DD001 DD241 DG002 DG212 GA03 MA02 MA14 NA01

Claims (6)

[Claims] 1. A binder resin comprising (A) a urethane-curable (a-1) hydroxyl-containing polyester resin and (a-2) a hydroxyl-containing polyurethane resin, and (B) a fine powder of a hydroxyl-containing polyurethane resin. A matte coating composition for in-mold coating, comprising: 2. The matte coating composition for in-mold coating according to claim 1, wherein the hydroxyl group-containing polyester resin (a-1) has a molecular weight of 10,000 to 40,000 and a hydroxyl value of 1
And the hydroxyl group-containing polyurethane resin of (a-2) has a molecular weight of 5,000 to 60,000 and a hydroxyl value of 70 to 180,
A matte coating composition for in-mold coating, wherein the weight ratio is (a-1): [(a-2) + (B)] = 20:80 to 50:50. 3. The matte coating composition for in-mold coating according to claim 1 or 2, wherein the hydroxyl group-containing polyurethane resin (a-2) is an acrylic-modified polyurethane resin. Matt coating film composition for mold coating. 4. The matte coating composition for in-mold coating according to claim 1, wherein the hydroxyl group-containing polyurethane resin fine powder of (B) has a hydroxyl value of 100 or more and 250 or less. A matte coating composition for in-mold coating, comprising: 5. The matte coating composition for in-mold coating according to claim 1, wherein the fine powder of the hydroxyl group-containing polyurethane resin (B) has an average particle size of 20 to 70.
A matte coating composition for in-mold coating characterized by having a particle size of μm. 6. The matte coating composition for in-mold coating according to any one of claims 1 to 5, wherein the hydroxyl group-containing polyurethane resin fine powder of (B) is 20 to 70 parts (provided that (A) + (B) is defined as 100 parts). A matte coating composition for in-mold coating.