JPH08113761A - Resin composition for in-mold coating and its production - Google Patents

Abstract

PURPOSE: To provide an in-mold coating resin composition which is excellent in weather resistance and miscibility and has a lowered curing temperature by mixing individual components giving a high-viscosity resin and a low-viscosity resin and allowing them to react with each other in a specific manner. CONSTITUTION: This composition is obtained by admixing a mixture formed by adding a low-viscosity (a) solution which forms a resin, when a (b) solution is added, a (B) solution and a (b) solution to a high-viscosity (A) solution which forms resin by reaction with the (B) solution followed by reaction. As a resin formed from the (A) and (B) solutions, is preferably an epoxy or a urethane resin. In the case that said resin is an epoxy resin, for example, an epoxy resin is used as an A solution, while an organic acid anhydride is used as a component (B). Further, the resin from (a) and (b) solutions are, for example, a vinyl ester resin and, in this case, the (a) solution is, for example, a mixture of a liquid hydrogenated bisphenol A vinyl ester resin, a styrene monomer and a cobalt naphthenate as an accelerator, and the (b) solution is a solution of styrene monomer and a curing agent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin composition for in-mold coating which is a paint used when a resin molded article molded in a mold is subjected to coating treatment in the mold, and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, SMC (seat
Molding compounds were often used. When the SMC is molded, air that is mixed into the SMC and leaks to the outside of the resin surface due to heating causes a narrow mouth on the resin surface. Since this narrow mouth causes a pinhole in the coating film during coating, a resin composition for in-mold coating has been developed to eliminate this pinhole during the intermediate coating step. With this paint for in-mold coating, S
When painting MC, 130 ° C-
The heat treatment is carried out at 150 ° C. At this time, air expanded by heating is blown out from the narrow mouth on the surface of the SMC, and at that time, a narrow mouth is easily generated even on the surface of the resin composition for in-mold coating. A resin as a resin composition for mold coating is selected and used.

As a conventional resin composition for in-mold coating, a one-pack type vinyl ester resin has been put into practical use. This one-pack type vinyl ester resin is mainly used as a primer for SMC, maintains a relatively low viscosity, has a curing temperature of 130 ° C. to 150 ° C., has low weather resistance, requires a top coat, and is used in a molding apparatus. The piston can be pressed in relatively easily. On the other hand, as a resin composition for in-mold coating in the development stage, there are two-pack type epoxy resin and urethane resin. It is desirable to use this two-pack type epoxy resin or urethane resin as a top coat. It maintains a relatively high viscosity, can be cured from about 80 ° C, and has a relatively high weather resistance. Was set in a RIM molding machine, and was subjected to RIM type collision mixing, and because the viscosity was high, it was pressed into the mold by a high pressure piston.

[0004]

As described above, the one-pack type vinyl ester resin is easy to supply into the mold, and the mixing and adjustment is easy because it is one pack, but the weatherability is low and the top coat However, it cannot be used as a thermoplastic resin because its curing temperature is relatively high. On the other hand, a two-pack type epoxy resin or urethane resin can be cured from about 80 ° C. and can be used as a thermoplastic resin and has high weather resistance and can be used as a top coat, but its viscosity is relatively high, so that mixing is insufficient. However, there is a problem that the viscosity cannot be adjusted by diluting the solvent. The object of each of the first to fourth aspects of the invention is to provide two liquids before reaction of a highly viscous resin,
It is an object of the present invention to provide a resin composition for in-mold coating which is highly weather-resistant, has good mixability, and has a low curing temperature by allowing two liquids of a low-viscosity resin to react at room temperature.
An object of each of the inventions of claims 5 to 6 is to produce a resin composition capable of easily accelerating a reaction to a resin by mixing a high-viscosity resin resin composition and a low-viscosity resin resin composition. The purpose is to provide a method.

[0005]

In order to achieve the above object, the invention of claim 1 forms a resin by adding solution b to solution A of high viscosity which reacts with solution B to form a resin. It is characterized in that the mixture of the low-viscosity liquid a, the liquid B, and the liquid b are mixed and reacted. The invention of claim 2 is characterized in that, in the fiber-reinforced resin of claim 1, the solutions A and B form an epoxy resin.
The invention of claim 3 is characterized in that, in the fiber-reinforced resin of claim 1, the liquid A and the liquid B form a urethane resin.

The invention of claim 4 is characterized in that, in the fiber-reinforced resin of claim 1, the liquids a and b form a vinyl ester resin. The invention of claim 5 provides a highly viscous liquid A which reacts with liquid B to form a resin,
It is characterized by reacting a mixture of the low-viscosity a liquid that forms a resin when the liquid b is added, a mixture of the liquid B and the liquid b. According to a sixth aspect of the present invention, in the fiber-reinforced resin according to the fifth aspect, the mixed liquid of the liquid A and liquid a,
It is characterized in that the liquid and the liquid b are subjected to RIM type collision mixing.

[0007]

According to the first aspect of the present invention, the two liquids before reaction of the high-viscosity resin, which is made into a resin by mixing the two liquids, are reacted with the two liquids before reaction of the low-viscosity resin, which are made into a resin by reacting at room temperature by mixing the two liquids. Since the two liquids before the reaction are prepared by premixing and the two liquids before the reaction are mixed, the mixing can be surely performed when the two liquids before the reaction are mixed. In the invention of claims 2 to 3, the high-viscosity resin of the resin composition for in-mold coating is
In particular, since the epoxy resin or the urethane resin is used, the weather resistance is high and the curing temperature is low.

In the invention of claim 4, since the low viscosity resin of the resin composition for in-mold coating is particularly a vinyl ester resin, the mixing property is particularly high. In the invention of claim 5, since the high-viscosity resin composition and the low-viscosity resin composition are mixed, the mixing is surely performed when the two liquids are mixed. In the sixth aspect of the present invention, since the RIM type collision mixing is performed, the mixing can be performed more reliably when the two liquids are mixed.

[0009]

EXAMPLES A resin composition for in-mold coating and a method for producing the same will be described below as an example of the present invention. PC is in-mold coated here
A molded product made of an alloy of (polycarbonate) and PBT (polybutylene terephthalate) (hereinafter simply referred to as (PC + PBT)), and this molded product forms the main part of the front panel 1 (see FIG. 1) of the cab type vehicle. . The front panel 1 includes the injection molding machine 36 and the molding machine 3 shown in FIG.
It is manufactured by the RIM type resin supply machine M attached to the mold 33 in 6. The injection molding machine 36 includes a mold 33 having a mold cavity 31, and the mold 33 is equipped with heating means 331 and cooling means 33. The mold 33 is clamped and opened at appropriate times by the clamping device 32, and a molded product can be molded and discharged. Mold cavity 3 here
1, first and second supply ports 2 and 3 are formed. An injection molding machine 36 filled with (PC + PBT) is connected to the first supply port 2, and a RIM type resin supply machine M is connected to the second supply port 3.

Here, the RIM type resin feeder M is provided with a first raw material tank 11 and a second raw material tank 12, the first raw material tank 11 stores a liquid I described later, and the second raw material tank 12
Liquid II, which will be described later, is stored in. Both tanks are connected to the first and second pipes 13 and 14 via the first and second transfer pumps 9 and 10.
And a pair of service tanks 16 and 17 with temperature adjusting means and metering pumps 18 and 19 are provided in the middle thereof, and the extending first and second pipes 13 and 14 are further provided.
Is connected to the I liquid inlet 22 and the II liquid inlet 23 of the mixing head 21.

The mixing head 21 includes a plunger 26 facing the hydraulic chamber 25 in a main body 24, and a plunger 2.
6, the other end of which is opposite to the pressurizing chamber 27, a pair of I liquid inlet 22 and II liquid inlet 23, which are opposed to the side wall of the plunger 26, and a pair of I liquid outlet 28 and II liquid outlet. And 29. The I liquid outlet 28 and the II liquid outlet 29 are formed so as to extend the return path toward the service tanks 16 and 17.

A hydraulic pressure supply system 30 is connected to the hydraulic chamber 25, and a mold cavity 31 communicates with the pressurizing chamber 27 via a high pressure pipe (not shown). The plunger 26 switches and slides according to the hydraulic pressure supplied from the hydraulic pressure supply system 30 to the hydraulic chamber 25. That is, the plunger 26 is formed with a pair of communication grooves 261 on both sides thereof, and when the plunger 26 is at the circulation position P1 (see the chain double-dashed line in FIG. 1), both liquids I and II described later are separately provided. When the plunger 26 is circulated and is at the discharge position P2 (see the solid line in FIG. 1), both liquids I and II can be introduced into the pressurizing chamber 27, mixed by collision, and supplied to the mold cavity 31. Less than,
A method of manufacturing the front panel (see FIG. 1) 1 of the cab type vehicle will be sequentially described.

Here, a molding process of the (PC + PBT) molded product forming the main part of the front panel 1 is performed. After this, before the demolding, an in-mold coating process is started. Here, the liquid I is supplied to the first raw material tank 11 and the liquid II is supplied to the second raw material tank 12 of the RIM type resin feeder M in advance. Here, liquid I is a mixture of liquid A having high viscosity and liquid a of low viscosity, and liquid II is a mixture of liquid B and liquid b. That is, epoxy is used as the highly viscous liquid A which reacts with liquid B to form a resin. As the liquid B here, a curing agent of an organic acid anhydride (see FIG. 5) is used, and these produce a two-pack type epoxy resin. As shown in FIG. 4, when this epoxy resin is addition-polymerized with an acid anhydride, a hard epoxy resin polymer is formed and a crosslinked structure can be formed.

On the other hand, as liquid a having a low viscosity which forms a resin when liquid b is added, (liquid) hydrogenated bisphenol A vinyl ester resin (see FIG. 5) and styrene monomer (see FIG. 2 (a)) are used. What melt | dissolved the cobalt naphthenate (refer FIG. 3) as an accelerator is used. As the liquid b (reactive monomer) here, a solution in which a styrene monomer and a curing agent (eg, acetylacetone, peroxide) are dissolved is used. Although the styrene monomer is used here, a methacrylic acid ester (see FIG. 2B) may be used instead. As shown in FIG. 5 (a), the vinyl ester resin produces a vinyl ester monomer (see FIG. 5 (b)) by a ring-opening addition reaction of an epoxy resin and (meth) acrylic acid. This is dissolved in styrene monomer to form a liquid vinyl ester resin.

A two-pack type vinyl ester resin consisting of liquids a and b undergoes a redox reaction, which is one of the room temperature reaction systems, at the time of mixing, and a cured vinyl ester resin that crosslinks in a terminal branched form (see FIG. d) is generated. here,
The liquid I of the two kinds of mixed liquids before the reaction was a high-viscosity epoxy resin as a liquid A, a low-viscosity vinyl ester resin (liquid) as a styrene monomer (see FIG. 2A). What melt | dissolved cobalt naphthenate (refer FIG. 3) is mixed and prepared in the 1st raw material tank 11. Solution II of the two kinds of mixed solution before the reaction is prepared by mixing the acid anhydride of the curing agent as the solution B and the styrene monomer and the curing agent dissolved as the solution b in the second raw material tank 12 To be done.

After the raw materials are supplied to the RIM type resin supply machine M in this manner, the in-mold coating process is started. Here, the liquid I is supplied to the service tank 16 and the liquid II is supplied to the service tank 17, respectively.
Are held at preset temperatures (about 60 °) and premixed. Here, both metering pumps 18 and 19 are driven, and at the same time, hydraulic pressure is supplied from the hydraulic pressure supply system 30 to the hydraulic chamber 25 of the mixing head 21. The plunger 26 is held at the circulation position P1, whereby the liquid I circulates in the first pipe 13 and the second pipe 1
Liquid II circulates through 4. After that, the plunger 26 is switched and held at the discharge position P2 for a predetermined injection time in accordance with the hydraulic pressure supplied from the hydraulic pressure supply system 30, and the circulating position P1 is again set.
And is kept in a standby state.

At the time of injecting this mixed liquid, both liquids are mixed under high pressure by the mixing head 21 and fed into the gap of the mold cavity 31, and both liquids I and II are applied to the outer surface of the (PC + PBT) molded product. The mixed liquid of 1 will adhere. At this time, first, a vinyl ester resin (liquid) which is liquid a in liquid I and a styrene monomer (see FIG. 2 (a))
A solution in which cobalt naphthenate is dissolved and a solution in which the styrene monomer which is the liquid b in the liquid II and the curing agent are dissolved undergo a redox reaction to accelerate the reaction. That is, at the initiation of radical polymerization, in the redox reaction, one electron is released when a monovalent cobalt ion is oxidized to divalent, and this electron forms an organic radical and a hydroxyl group. The organic radical acts as a reaction initiator to accelerate the reaction.

Such a redox reaction acts on the vinyl ester resin (liquid) which is the liquid a to form a cured vinyl ester resin (see FIG. 5 (d)) that crosslinks in a terminally branched form, and accelerates the curing. Here, at the stage where the cured vinyl ester resin is produced, the demolding process is started, the clamping device 32 is operated to open the mold, and the mold cavity 31 is opened.
In-mold coated inside (PC + PBT)
The front panel 1 which is a molded product is discharged. The front panel 1, which is the in-mold coated (PC + PBT) molded product, is subjected to a post-curing step after releasing the mold. Here, in the curing furnace (not shown) (PC + PBT)
The front panel 1, which is a molded product, is conveyed for a predetermined time,
It is kept warm at a predetermined temperature (80 ° C). During this period, A in liquid I
The liquid epoxy resin and the acid anhydride as the curing agent in the liquid II undergo a crosslinking reaction as shown in FIG. 5 to produce a cured two-pack type epoxy resin. As a result, a (PC + PBT) molded article coated with the paint, which is a completely cured resin composition for in-mold coating, is manufactured as the front panel 1.

The front panel 1 manufactured as described above is prepared by applying the resin composition for in-mold coating at a low temperature (80%).
Since the reaction was carried out at room temperature at (° C.), a resin such as (PC + PBT) can be used. In particular, since the resin composition for in-mold coating contains a two-pack type epoxy resin, it has high weatherability and can be used as a top coat. Further, since it contains a two-pack type vinyl ester resin, the mixing property is improved and the RIM formula The resin feeder M can be used and workability is excellent. In the above description, of the resin composition for in-mold coating, the cured vinyl ester resin (see FIG. 5D) is the mold 3
Since a two-pack type epoxy resin which is cured in 3 and cured in the post-curing step is generated, there is an advantage that the molding cycle in the molding machine 1 can be shortened. In addition, you may perform a post-curing process in the molding machine 1 depending on the case. In the above-described first embodiment, the epoxy resin is used as the high-viscosity liquid A and the acid anhydride is used as the curing agent for the liquid B, but instead of this, the following configuration may be adopted.

The second embodiment is different from the first embodiment in that
Among the resin materials forming liquid I and liquid II, liquid A and liquid B are different, liquid a and liquid b are the same, the manufacturing process is the same, and the explanation of overlapping parts is simplified here. To do. Here, isocyanate (here, tetramethylene diisocyanate) (see FIG. 6) is used as the high-viscosity liquid A that reacts with liquid B to form a resin, and the liquid B here is an active hydrogen compound. Certain polyols (here hexamethylene glycol) (see FIG. 6) are used and these produce a two-part urethane resin. As shown in FIG. 6, an isocyanate (here, tetramethylene diisocyanate) NCO group and a polyol (here, hexamethylene glycol) cause an addition polymerization (curing) reaction of an OH group, and a polyurethane having a crosslinked structure can be produced.

As the liquid a having a low viscosity which forms a resin when the liquid b is added, the same vinyl ester resin and styrene monomer (see FIG. 2 (a)) as in the first embodiment are added to the organic cobalt naphthenate as an accelerator. (See FIG. 3) is used, and as the solution b, a solution in which a curing agent is dissolved in a styrene monomer is used. Here, the liquid I is a highly viscous A
Isocyanate as a liquid (see FIG. 6) and a low viscosity a
A vinyl ester resin (liquid) as a liquid and a mixture of a styrene monomer and an organic cobalt naphthenate (see FIG. 3) as a promoter dissolved therein are mixed, and the first raw material tank 11
Be prepared for. The liquid II is prepared by mixing the polyol (here, hexamethylene glycol) as the liquid B (see FIG. 6) and the styrene monomer as the liquid b in which the curing agent is dissolved, and is prepared in the second raw material tank 12.

After the raw materials are supplied to the RIM type resin supply machine M in this manner, the in-mold coating process is started. Here, at the time of injecting the mixed liquid, both liquids I and II are mixed under high pressure in the mixing head 21, and (PC + PB
The T) product is sent into the gap of the mold cavity 31 filled with the product, and the mixed liquid of both liquids I and II adheres to the outer surface of the (PC + PBT) product. At this time, first, after dissolving cobalt naphthenate as a promoter in vinyl ester resin (liquid) which is liquid a in liquid I and styrene monomer (see FIG. 2 (a)), b in liquid II is dissolved. A solution of a styrene monomer that is a liquid and a curing agent undergoes a redox reaction, the reaction is promoted, and the vinyl ester resin (liquid) that is a liquid is cross-linked in a terminal branched form, and a cured vinyl ester resin (see FIG. d)) is produced and curing is accelerated. At the same time, the isocyanate, which is the liquid A in the liquid I, and the polyol, which is the liquid B in the liquid II, undergo an addition polymerization reaction as shown in FIG. 6 to produce a cured two-component urethane resin.

At the stage where the cured vinyl ester resin is produced, a demolding process is started, and the in-mold coated (PC + PBT) molded product is discharged in the mold cavity 31 and subjected to the post-curing process. Here, the front panel 1, which is a (PC + PBT) molded product, is conveyed into a curing furnace (not shown) and is kept at a predetermined temperature (80
It is kept warm at (℃). As a result, the front panel 1 of the (PC + PBT) molded article coated with the paint which is the completely cured resin composition for in-mold coating is manufactured. The resin composition for in-mold coating of the second embodiment also has the same effects as those of the first embodiment.

In the above description, the front panel 1
The main part of the above is a molded product made of (PC + PBT), but other thermoplastic resins can be used and the same effect can be obtained. Further, in some cases, the main portion of the front panel 1 may be molded by the conventional SMC.

[0025]

As described above, according to the first aspect of the present invention, the two liquids before the reaction of the high-viscosity resin which is resinified by the mixing of the two liquids are reacted at room temperature by the mixing of the two liquids to form the resin of a low viscosity. By mixing the two liquids before reaction of the resin in advance to prepare two types of mixed liquids before the reaction and mixing the two types of mixed liquids before the reaction, the weatherability is high and the mixing property is good. A resin composition for in-mold coating having a low curing temperature can be produced. When the high-viscosity resin which is used to produce the resin composition for in-mold coating according to claim 2 and claim 3 and which is made into a resin by mixing two liquids, is an epoxy resin or a urethane resin, in-mold coating The weather resistance of the resin composition for use can be higher, and the curing temperature can be lower.

When the low-viscosity resin which is used to produce the resin composition for in-mold coating according to claim 4 and which is made into a resin by mixing two liquids is a vinyl ester resin,
The mixability of the resin composition for in-mold coating is further improved. According to the invention of claim 5, the resin composition for in-mold coating is obtained by mixing the resin composition of high viscosity and the resin composition of low viscosity, so that the mixing property at the time of formation can be improved and the curing temperature can be kept low. The weather resistance of the obtained resin composition can be increased. According to the invention of claim 6, in mixing a high-viscosity resin composition and a low-viscosity resin composition, RI is particularly preferable.
Since the M type collision mixing is performed, the mixing work at the time of generation is facilitated.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a molding machine and a RIM type resin supply machine used for producing a resin composition for in-mold coating of the present invention.

FIG. 2 is a diagram showing the state formulas of (a) styrene and (b) methacrylic acid ester used for producing the resin composition for in-mold coating of the present invention.

FIG. 3 is a diagram of a state formula of cobalt naphthenate used for producing the resin composition for in-mold coating of the present invention.

FIG. 4 is a cross-sectional structure model diagram of an epoxy resin used for producing the resin composition for in-mold coating of the present invention, which is obtained by curing with an acid anhydride.

FIG. 5 is a diagram showing a state equation of a vinyl ester resin used for producing the resin composition for in-mold coating of the present invention, where (a) is a starting material, (b) is a vinyl ester monomer, and (c). Liquid vinyl ester resin (d)
A cured vinyl ester resin is shown.

FIG. 6 is a diagram showing a chemical reaction formula of a urethane resin used for producing the resin composition for in-mold coating of the present invention.

[Explanation of symbols]

 1 Front Panel 21 Mixing Head 31 Mold Cavity 32 Clamping Device 33 Type 34 Pressurizing Pump 36 Injection Molding Machine M RIM Type Resin Supply Machine

Claims (6)

[Claims] 1. A highly viscous A which reacts with liquid B to form a resin.
A resin composition for in-mold coating, which comprises reacting a mixture of a liquid with a low viscosity a which forms a resin when liquid b is added, a liquid B and a liquid b. 2. The resin composition for in-mold coating according to claim 1, wherein the solutions A and B form an epoxy resin. 3. The resin composition for in-mold coating according to claim 1, wherein the solutions A and B form a urethane resin. 4. The resin composition for in-mold coating according to claim 1, wherein the liquids a and b form a vinyl ester resin. 5. A highly viscous A which reacts with liquid B to form a resin.
A method for producing a resin composition, which comprises reacting a mixture of liquid a with liquid a having low viscosity when liquid b is added to liquid, and liquid B and liquid b. 6. The method for producing a resin composition according to claim 5, wherein the mixed solution of the liquid A and the liquid a, the liquid B, and the liquid b are subjected to RIM collision mixing.