JP2007313395A - In-mold coating method and coated molding - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an in-mold coating method capable of forming an even cover coating film without causing a non-coated defective portion even if a coated object is a big molding and a coated molding obtained thereby. <P>SOLUTION: In-mold coating method that injects a cover into a cover coating space formed by a resin molding and a mold from cover injection ports provided at the mold to form a cover layer on a surface of the resin molding, after forming a resin where a resin material is injected into a cavity formed by the mold of a pair of male mold and female mold, wherein a surface area of the cover coating on the resin molding is 2 m<SP>2</SP>or more, a settling starting time at 90°C thereof is 60 seconds or more and 200 seconds or less, a cover with a viscosity of 3,500 Pa/s or less is used, and the cover injection ports are provided so as to allow the shortest flowing distance to be 1.3 m or less out of distances between all points in the cover coating space and each of the cover injection ports. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an in-mold coating method capable of forming a uniform coating film without causing a non-paint defect portion even in a large molded body. More specifically, even when the surface area of the molded article to be coated with a coating material is large by using a coating material having specific characteristics and providing a coating material inlet so as to satisfy specific conditions. The present invention relates to an in-mold coating method capable of forming a uniform coating film without producing a non-paint defect portion, and a coated molded body obtained by using this in-mold coating method.

Large molded products used for automobile parts such as bumpers and air deflectors, construction and industrial machines such as wheel loaders and power shovels, leisure equipment such as golf cars and game machines, housing equipment such as wash bowls, unit baths and panels Recently, it is manufactured by reaction injection molding. In order to impart characteristics such as designability and weather resistance to the resin molded body used in each of these uses, a coating film is formed.
Recently, an in-mold coating method is mainly used for forming the coating film. The in-mold coating method is a phenomenon in which the volume shrinks when a reaction stock solution containing a resin raw material monomer, a polymerization catalyst, a catalyst activating component and the like becomes a molded body in the production of a molded body by a reaction injection molding method, so-called molding. In this method, a coating agent is injected into a gap of about 5 to 500 μm between the mold and the molded body caused by shrinkage and cured to form a coating film on the molded body. After the in-mold coating, the molded body having the coating film is taken out from the mold.

However, in the case of a large molded article, the thickness of the coating is relatively thick at the portion near the coating inlet and relatively thin at the portion far from the inlet, and the coating thickness is uniform as a whole. There is a problem that is not.
In order to solve such a problem, the applicant of Patent Document 1 discloses that the flow rate of the coating material is within a specific range at all joint points where the coating materials injected from the plurality of coating material injection ports are joined. By doing so, it was reported that a uniform coating film could be formed without causing appearance defects such as welds.
However, subsequent investigations have revealed that even with the above-described method, a portion that is not partially coated is generated in some cases.

JP 2005-246880 A

  Accordingly, an object of the present invention is to provide an in-mold coating method which can obtain a uniform coating film without a coating defect such as a coating defect even in a large molded body. Another object of the present invention is to provide a large molded article having a uniform coating film free from coating defects such as coating defects.

  As a result of earnest research on the coating material used in the in-mold coating method, the present inventor made the curing rate and viscosity of the coating material within a specific range, and further, between the coating material injection ports. The inventors have found that the above object can be achieved by setting the distance within a specific range, and have completed the present invention based on this finding.

Thus, according to the present invention, following the resin molding in which the resin material is injected into the cavity formed by the male mold and the female mold, a coating agent coating space formed by the resin molded body and the mold. In an in-mold coating method in which a coating agent is injected from a coating agent injection port provided in a mold to form a coating layer on the surface of the resin molding, (1) the coating surface area of the resin molding is 2 m ^2. (2) Using a coating agent having a curing start time at 90 ° C. of 60 seconds or more and 200 seconds or less and a viscosity of 3,500 mPa · s or less, and (3) In the coating agent coating space An in-mold coating method is provided in which a coating agent injection port is provided so that the shortest flow distance from each point to each coating agent injection port is 1.3 m or less. Is done.
In the in-mold coating method of the present invention, the coating agent preferably contains 0.06 to 2% by weight of an anti-aging agent.

In the in-mold coating method of the present invention, the resin molding is preferably reaction injection molding.
Moreover, according to this invention, the coating molded object obtained by the said in-mold coating method is provided.

According to the present invention, it is possible to obtain a molded body having a uniform coating film having no coating defects even if it is a large reaction injection molded body.
The in-mold coating method of the present invention can be suitably applied to the production of a coated molded body having a resin surface area of 2 m ² or more. Examples of such a large coated molded body include a truck cover, a bathtub, a washing bath pan for a unit bath, a washing machine pan, a concrete panel, and the like. In particular, as in the case of the track cover, the cavity of the mold is greatly bent, and there is a partition part in the middle of the cavity of the mold, and therefore in-mold coating is performed from both sides of the partition part. It is effective when necessary.
Since this coated molded body has a uniform coating film, no coating defects, and is excellent in design, it can be suitably used for automotive parts, construction / industrial machines, leisure equipment, housing facilities, and the like.

  The in-mold coating method is a resin coating method in which a resin material is injected into a cavity formed by a male mold and a female mold, followed by a coating material coating space formed by a resin molded body and a mold. In this method, a coating agent is injected from a coating agent injection port provided in a mold to form a coating layer on the surface of the resin molded body.

The coating agent used in the present invention is required to have a curing start time at 90 ° C. of 60 seconds or more and 200 seconds or less. The curing start time is more preferably 70 seconds or longer, and particularly preferably 75 seconds or longer.
When the curing start time is shorter than the lower limit, a uniform coating film cannot be formed, and a non-coating defect portion is generated. On the other hand, when the curing start time is longer than the above upper limit, the adhesion of the coating film to the molded body is deteriorated.
The term “curing” refers to a state in which one drop of the coating agent is dropped on a 90 ° C. plate and the surface is cured and does not flow.

The coating agent used in the present invention is not particularly limited, and specific examples thereof include various hard coat agents such as paints, fluororesin lacquers, silicone resin lacquers, and silane hard coat agents. However, a paint is preferably used.
The paint includes (a) an unsaturated polyester resin, epoxy acrylate oligomer, polyester acrylate oligomer or urethane acrylate oligomer, (b) a vehicle component containing an ethylenically unsaturated monomer copolymerizable therewith, and (c) A paint containing a radical polymerization initiator is preferred.

  Unsaturated polyester resins, epoxy acrylate oligomers, polyester acrylate oligomers and urethane acrylate oligomers all have unsaturated double bonds in the molecule, and ethylenically unsaturated monomers are generated by active radicals generated from radical polymerization initiators. Copolymerization (curing reaction) with a vehicle component consisting of

  The unsaturated polyester resin that can be used in the present invention is produced, for example, by a condensation reaction between an unsaturated dibasic acid such as maleic acid or fumaric acid and a polyhydric alcohol such as ethylene glycol, propylene glycol, or trimethylolpropane. Can do.

  The epoxy acrylate oligomer is a ring-opening addition reaction between an epoxy compound and an unsaturated carboxylic acid such as acrylic acid or methacrylic acid at a ratio such that the carboxyl group equivalent is 0.5 to 1.5 equivalents per equivalent of epoxy group. It is manufactured.

The polyester acrylate oligomer can be produced, for example, by a reaction between a polyester polyol having a hydroxyl group at the terminal and the aforementioned unsaturated carboxylic acid.
The polyether acrylate oligomer can be produced, for example, by reacting a polyether polyol such as polyethylene glycol or polypropylene glycol with the aforementioned unsaturated carboxylic acid.

  The urethane acrylate oligomer can be obtained by batch mixing and reacting a diisocyanate compound, a diol compound and a hydroxyl group-containing (meth) acrylate. As another method, a diol compound and a diisocyanate compound are reacted to form a urethane isocyanate intermediate containing one or more isocyanate groups per molecule, and then the intermediate and a hydroxyl group-containing (meth) acrylate group A reaction of a diisocyanate compound with a hydroxyl group-containing (meth) acrylate to form a urethane (meth) acrylate intermediate containing one or more isocyanate groups per molecule, and then the intermediate and diol Examples thereof include a method of reacting with a compound.

  Various known compounds can be used as the diisocyanate compound. Specifically, organic diisocyanates such as tolylene diisocyanate, isophorone diisocyanate, polymethylene polyphenyl diisocyanate, 1,2-diisocyanatoethane, hexamethylene diisocyanate, 1,3-bis (isocyanatomethyl) cyclohexane Can do. These diisocyanate compounds may be used alone or as a mixture.

Typical examples of the diol compound include alkylene glycol such as ethylene glycol, propylene glycol, diethylene glycol, polyethylene glycol, and polypropylene glycol, and diester diol that is a diester reaction product of dicarboxylic acid or its anhydride.
Furthermore, as the hydroxyalkyl (meth) acrylate, for example, the general _{formula: CH 2 = CRCO 2 - (} C n H 2n) -OH ( Here, R is -H or -CH _3, n is 2 to 8 Which is an integer of) is useful.

  A particularly preferable paint is a paint mainly composed of an epoxy acrylate oligomer or a urethane acrylate oligomer.

Examples of the ethylenically unsaturated monomer that can be used in the present invention include styrene, α-methylstyrene, chlorostyrene, vinyltoluene, divinylbenzene, methyl (meth) acrylate, 1,6-hexanediol diacrylate, and tripropylene. Typical examples include glycol diacrylate, trimethylolpropane tri (meth) acrylate, silicone acrylate, and silicone diacrylate, but are not limited thereto.
The amount of the ethylenically unsaturated monomer is appropriately 20 to 200 parts by weight, preferably 40 to 160 parts by weight, based on 100 parts by weight of the vehicle component, and a coating agent having appropriate curing characteristics and viscosity within this range. Is obtained.

The (c) radical polymerization initiator for polymerizing the component (a) and the component (b) is not particularly limited, but an organic peroxide is preferable, and a one-minute half-life temperature of 90 to 135 ° C. is particularly preferable. preferable.
Specific examples thereof include, but are not limited to, for example, bis (4-t-butylcyclohexyl) peroxydicarbonate, diisopropyl peroxydicarbonate, t-butylperoxyneodecanoate, t-butylperoxyneo Hexanoate, t-butylperoxyneoheptanoate, t-hexylperoxyneodecanoate, t-butylperoxypivalate, lauroyl peroxide, 2,4,4-trimethylpentylperoxy-2-ethyl Typical examples include hexanoate, t-amylperoxy-2-ethylhexanoate, benzoyl peroxide, t-butylperoxy-2-ethylhexanoate, and the like.
0.1-15 weight part is preferable with respect to 100 weight part of vehicle components, and, as for the compounding quantity of an organic peroxide polymerization initiator, 1-8 weight part is more preferable.

  These paints used in the present invention can sufficiently adhere to the surface of the molded body without using a primer. This is because the active radicals generated during the curing reaction of the paint react with the unsaturated bonds remaining in the crosslinked resin molded body formed from the cyclic olefin, resulting in a chemical bond between the molded body and the paint. This is thought to be due to the development of strong adhesion.

The viscosity of the coating material used in the present invention is 3,500 mPa · s or less, preferably 3,000 mPa · s or less, preferably from 3,000 mPa · s or less in measurement at a B-type viscometer at 30 ° C. from the viewpoint of suppressing wraparound and generation of bubbles. Particularly preferably, it is 2,500 mPa · s or less.
When the viscosity of the coating agent exceeds 3,500 mPa, the flow of the coating agent is remarkably deteriorated and a coating defect may occur.

In this invention, it is preferable that a coating material contains 0.06 to 2 weight% of anti-aging agent with respect to the weight.
The anti-aging agent is not particularly limited, but various types of anti-aging agents for plastics and rubbers such as phenol, phosphorus and amine can be used.

  Examples of the phenolic anti-aging agent include 4,4-dioxydiphenyl, hydroquinone monobenzyl ether, 2,4-dimethyl-6-t-butylphenol, 2,6-di-t-butylphenol, 2,6- Di-t-amylhydroquinone, 2,6-di-t-butyl-p-cresol, 4-hydroxymethyl-2,6-di-t-butylphenol, 4,4'-methylene-bis- (6-t- Butyl-o-cresol), 4,4′-methylene-bis- (2,6-di-t-butylphenol), 1,3,5-trimethyl-2,4,6-tris (3,5-di-) t-butyl-4-hydroxybenzyl) benzene, octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, pentaerythrityl-tetrakis [3- (3 5-di -t- butyl-4-hydroxyphenyl) propionate], butylated hydroxy anisole, phenol condensates, butylene phenol, dialkyl phenol sulfide, high molecular weight polyhydric phenols, bisphenols, and the like.

Examples of phosphorus-based antioxidants include aryl or alkylaryl phosphites such as tri (phenyl) phosphite, tris (noniphenyl) phosphite, tris (2,4-di-t-butylphenyl) phosphite. Can be mentioned.
Examples of the amine anti-aging agent include phenyl-α-naphthylamine, phenyl-β-naphthylamine, 4,4′-dioctylphenylamine, N, N′-di-β-naphthyl-p-phenylenediamine, N, N. Examples include '-diphenyl-p-phenylenediamine, N-phenyl-N'-cyclohexyl-p-phenylenediamine, N, N'-di-o-tolyl-ethylenediamine, and alkylated diphenylamine.
These anti-aging agents may be used alone or in combination of two or more.

Furthermore, the ultraviolet absorber currently used as the light stabilizer of a plastics or rubber | gum can be added to the coating material used by this invention.
Examples of the ultraviolet absorber include 4-t-butylphenyl salicylate, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-n-octoxybenzophenone, ethyl-2-cyano-3,3-diphenyl. Acrylate, 2-ethylhexyl-2-cyano-3,3-diphenyl acrylate, phenyl salicite, 2,2′-dihydroxy-4,4′-dimethoxybenzophenone, 2,2 ′, 4,4′-tetrahydroxybenzophenone, 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-t-butylphenyl) benzotriazole, bis (2,2,6,6) -Tetramethyl-4-piperidine) sebacate, 4-[(N-ethyl-N-phenylamino) methylenamino] ben Dichroic acid ethyl ether, and the like.

In addition to the components (a), (b) and (c), the anti-aging agent, and the UV absorber, the paint used in the present invention may further include a metal powder, a release agent, a curing accelerator, A polymerization inhibitor, a light stabilizer, a color pigment, an extender pigment, a conductive pigment, a modified resin, a surface conditioner, and the like can be added.
Typical curing accelerators include, but are not limited to, cobalt naphthenate, cobalt octylate, zinc naphthenate, zinc octylate, manganese naphthenate, lead naphthenate, or mixtures thereof. An appropriate amount of the accelerator is 0.01 to 20 parts by weight, preferably 0.04 to 10 parts by weight per 100 parts by weight of the vehicle component.
As the mold release agent, a mold release agent having a melting point of 125 ° C. or lower is used. Examples of such release agents include stearic acid, hydroxystearic acid, zinc stearate, soybean oil lecithin, silicone oil, fatty acid esters, fatty acid alcohol dibasic acid esters, and fluorine compounds such as hexafluoropropene oligomers, A typical example is wax.
If the melting point of the release agent is higher than 125 ° C., the molding temperature of the norbornene monomer is usually 65 to 95 ° C. Even if the increase in the surface temperature of the cured product due to the reaction heat of the norbornene monomer is taken into account, The mold does not melt sufficiently and the original mold release effect is difficult to obtain. The release agent may be liquid at normal temperature.
The compounding amount of the release agent is suitably 0.1 to 15 parts by weight, preferably 0.3 to 5 parts by weight with respect to 100 parts by weight of the vehicle component, and the release effect is exhibited within this range.

Examples of the polymerization inhibitor include hydroquinone, benzoquinone, para-t-butylcatechol, and the like.
Examples of the color pigment include titanium oxide, iron oxide, phthalocyanine blue, phthalocyanine green, and carbon black.
Examples of extender pigments include calcium carbonate, talc, silica, clay, mica, barium sulfate, aluminum hydroxide, and the like.
Examples of the conductive pigment include conductive carbon black and graphite.
The modified resin must be compatible with the vehicle component, and specific examples thereof include polymethyl methacrylate, polyvinyl acetate, saturated polyester, chlorinated polyolefin, and the like.

In the in-mold coating method of the present invention, first, resin molding is performed by injecting a resin material from an injection port provided in a mold into a cavity formed by a pair of male and female molds. Do.
The resin molding method is not particularly limited, but a reactive injection molding method (RIM molding method) is preferable.
Further, the resin material is not particularly limited, but a metathesis polymerizable cyclic olefin is preferable, and it is particularly preferable to subject the mixture containing the metathesis polymerizable cyclic olefin, the metathesis polymerizable catalyst component and the polymerization catalyst activation component to reaction injection molding. .
In the reaction injection molding, a metathesis polymerizable cyclic olefin containing a metathesis polymerization catalyst component (referred to as “solution A”) and a metathesis polymerizable cyclic olefin containing a metathesis polymerization activating component (referred to as “solution B”) are used. A method of mixing with a mixing head, injecting the mixture into a mold from a resin injection port, and performing metathesis polymerization and molding all at once in the mold is preferable.
Solution A, solution B, and other raw materials used for reaction injection molding may be collectively referred to as “reaction stock solution”.
The molding time varies depending on the cyclic olefin, the catalyst component, the activation component, the composition ratio thereof, the mold temperature, etc., but is not uniform, but is generally 5 seconds to 6 minutes, preferably 10 seconds to 5 minutes.
There is no particular limitation on the mold used for reaction injection molding.
The material of the mold is not particularly limited, and specific examples thereof include steel, cast or forged aluminum, zinc alloy casting or thermal spraying, nickel or copper electroforming, nickel, copper, chromium plating, etc. Or a resin or the like. The structure of the mold may be determined in consideration of the pressure when the reaction stock solution and the coating agent are injected into the mold. The mold clamping pressure is 0.1 to 9.8 MPa in gauge pressure.

The metathesis polymerizable cyclic olefin used in the present invention is not particularly limited, but a norbornene monomer is preferable.
The norbornene-based monomer only needs to have a norbornene ring. Specific examples thereof include bicyclic compounds such as norbornene and norbornadiene, tricyclic compounds such as dicyclopentadiene and dihydrodicyclopentadiene, and tetracyclododecene. Mention may be made of tetracycles, pentacycles such as cyclopentadiene trimer, and heptacycles such as cyclopentadiene tetramer. These bicyclic to heptacyclic compounds have hydrocarbon groups such as alkyl groups, alkenyl groups, alkylidene groups, and aryl groups, and polar groups such as ester groups, ether groups, cyano groups, and halogen atoms as substituents. May be. Among them, a tricyclic or higher polycyclic norbornene monomer is preferable because it is easily available and has excellent reactivity, and a tricyclic to pentacyclic norbornene monomer is more preferable.

Specific examples of the norbornene-based monomer include dicyclopentadiene, tricyclopentadiene, cyclopentadiene-methylcyclopentadiene codimer, 5-ethylidene norbornene, norbornene, norbornadiene, 5-cyclohexenyl norbornene, 1,4,5,8 Dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 1,4-methano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6 -Ethylidene-1,4,5,8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-ethylidene-1,4-methano-1,4,4a, 5 , 6,7,8,8a-octahydronaphthalene, 1,4,5,8-dimethano-1,4,4a, 5,6,7,8,8a-hexahydrona Array type, although ethylene bis (5-norbornene), and the like, dicyclopentadiene are particularly preferably used.
Norbornene monomers may be used alone or in combination of two or more.
In addition, monocyclic cycloolefins such as cyclobutene, cyclopentene, cyclopentadiene, cyclooctene, and cyclododecene can be used as a comonomer.

The polymerization catalyst component is preferably a metathesis polymerization catalyst.
The metathesis polymerization catalyst is not particularly limited as long as it is a catalyst capable of ring-opening polymerization of a norbornene-based monomer.
The metathesis polymerization catalyst is a complex formed by bonding a plurality of ions, atoms, polyatomic ions and / or compounds with a transition metal atom as a central atom. As transition metal atoms, atoms of Groups 5, 6 and 8 (long period periodic table, the same applies hereinafter) are used. Although the atoms of each group are not particularly limited, examples of the Group 5 atom include tantalum, examples of the Group 6 atom include molybdenum and tungsten, and examples of the Group 8 atom include ruthenium. And osmium.

Metathesis polymerization catalysts having group 6 tungsten or molybdenum as the central metal include metal halides such as tungsten hexachloride; metal oxyhalides such as tungsten chlorine oxide; metal oxides such as tungsten oxide; and tridodecylammonium Organometallic acid ammonium salts such as molybdate and tri (tridecyl) ammonium molybdate can be used.
In these, the organic molybdate ammonium salt is preferable. When these metathesis polymerization catalysts are used, it is preferable to use an organoaluminum compound or an organotin compound as an activator (cocatalyst) for the purpose of controlling the polymerization activity.

In the present invention, it is also preferable to use a metal carbene complex having a metal atom of Groups 5, 6 and 8 as a central metal as a metathesis polymerization catalyst. Of the metal carbene complexes, Group 8 ruthenium and osmium carbene complexes are preferred, and ruthenium carbene complexes are particularly preferred. Because the activity of the catalyst at the time of bulk polymerization is excellent, the productivity of norbornene-based resin moldings is excellent, and the resulting norbornene-based resin moldings have little odor derived from unreacted norbornene-based monomers, and are excellent in productivity. is there.
Among the ruthenium carbene complexes, a ruthenium carbene complex in which at least two carbene carbons are bonded to a ruthenium metal atom, and a group containing a hetero atom is bonded to at least one of the carbene carbons is particularly preferable.

  The amount of the metathesis polymerization catalyst used is usually 0.01 mmol or more, preferably 0.1 mmol or more, and 50 mmol or less, preferably 20 mmol or less with respect to 1 mol of the monomer used in the reaction. If the amount of metathesis polymerization catalyst used is too small, the polymerization activity will be too low and the reaction will take a long time, resulting in poor production efficiency. If the amount used is too large, the reaction will be too intense, so it will cure before being fully filled in the mold. And the catalyst is likely to precipitate, making it difficult to store homogeneously.

In the polymerization, an activator (cocatalyst) is used as necessary.
The activator (cocatalyst) is not particularly limited, and specific examples thereof include organometallic compounds of metals in Groups 11 to 14 of the periodic table. Specific examples thereof include organic aluminum compounds such as alkylaluminum halides such as ethylaluminum dichloride and diethylaluminum chloride and alkoxyalkylaluminum halides; organotin compounds such as tetrabutyltin; and the like. In addition, when using a ruthenium carbene complex as a metathesis polymerization catalyst, it is not necessary to use an activator.

The amount of the activator used is not particularly limited, but is usually 0.1 mol or more, preferably 1 mol or more, and 100 mol or less, preferably 10 mol or less with respect to 1 mol of the metathesis polymerization catalyst used in the reaction. is there. If the activator is not used or if the amount of the activator used is too small, the polymerization activity is too low and the reaction takes time, resulting in poor production efficiency. Conversely, if the amount used is too large, the reaction may be so intense that it may harden before it is fully filled in the mold.
The activator is used after being dissolved in the monomer, but within a range that does not substantially impair the properties of the molded article by the reaction injection molding method, it is suspended in a small amount of solvent and then mixed with the monomer. You may use it, making it difficult to precipitate or improving solubility.

Moreover, it is preferable to add an activity regulator as a component of the reaction stock solution. The activity regulator is for preventing the polymerization from starting during the injection when the polymerization catalyst monomer solution and the activator monomer solution B are mixed and injected into the mold to start the polymerization. As such a regulator, Lewis base is suitable, and ether, ester, nitrile and the like are used. Specific examples include butyl ether, ethyl benzoate, diglyme and the like. When a polar group-containing monomer is used as the copolymerization monomer, the monomer itself may be a Lewis base, and may also have an action as a regulator.
The regulator is preferably added to the solution B containing the activating component.

  In the present invention, in order to improve or maintain the properties of the molded product, various additives may be added to the reaction stock solution within a range that does not impair the adhesion, adhesion, etc. between the cured coating and the molded product. Such additives include reinforcing materials, anti-aging agents, heat stabilizers, light stabilizers, UV absorbers, fillers, pigments, colorants, foaming agents, antistatic agents, flame retardants, lubricants, softeners, and tackifiers. Agents, plasticizers, mold release agents, deodorants, fragrances, elastomers, dicyclopentadiene-based thermal polymerization resins and hydrogenated products thereof.

  Various additives are added to the catalyst or activator monomer solution; used as a separate monomer solution and mixed with the catalyst or activator monomer solution during reaction injection molding; It is added by the method; What is necessary is just to select suitably the addition method with the kind of additive.

  The temperature of the reaction stock solution before supply is preferably 10 to 60 ° C., and the viscosity of the reaction stock solution is usually 5 to 3,000 mPa · s, preferably about 50 to 1,000 mPa · s at 30 ° C., for example. is there.

In the case where the reaction stock solution is supplied into a cavity formed by a male mold and a female mold, and bulk polymerization is performed, the male mold temperature T1 (° C.) is changed to the female mold temperature T2. It is preferable to set higher than (° C.). Thereby, the surface on which the coating film is formed in the molded body can be a beautiful surface with no surface marks or bubbles, which can contribute to improving the adhesion of the coating film.
T1-T2 has a lower limit of preferably 5 ° C or higher, more preferably 10 ° C or higher, and an upper limit of preferably 60 ° C or lower. T1 is preferably 110 ° C. or lower, more preferably 95 ° C. or lower, and the lower limit is preferably 50 ° C. or higher. T2 is preferably 70 ° C. or lower, more preferably 60 ° C. or lower, and the lower limit is preferably 30 ° C. or higher.
Examples of the method for adjusting the mold temperature include adjusting the mold temperature with a heater; adjusting the temperature of a heat medium such as temperature-controlled water and oil that is circulated in a pipe embedded in the mold.

As the polymerization in the cavity proceeds, a resin molded body is obtained, and molding shrinkage that occurs during molding (produced by reducing the volume of the molded body raw material through polymerization) causes a gap between the resin molded body and the mold. A gap (hereinafter, this may be referred to as a “coating application space”) occurs.
After the reaction injection molding is completed, in the same mold, a coating agent is injected into a coating agent coating space formed by the obtained resin molded body and the mold from a coating agent injection port provided in the mold, After the coating is cured, the coated molded body is removed from the mold. The coating agent inlet can also be used as a resin inlet.

The timing of injecting the coating agent from the coating agent injection port is from the time when the resin material monomer and the like are injected into the cavity and then the bulk polymerization reaction occurs inside the mold and the temperature of the molded body reaches the maximum temperature. Preferably after 5 seconds to within 20 minutes, more preferably after 5 seconds to within 10 minutes, particularly preferably within 10 seconds to within 5 minutes. If the timing of injecting the coating agent is too early, the reaction of the reaction solution of the molding material may be immature and may be deformed by the injection pressure of the coating agent. On the other hand, if the timing of injecting the coating agent is too late, the difference between the place where the shrinkage of the molded body becomes large and the place where the shrinkage does not become significant becomes significant, and the coating spot becomes large and the aesthetic appearance may be remarkably lowered.
The mold temperature of the male mold when the coating agent is injected into the coating agent coating space may be lower than the curing temperature of the coating agent, but is set to be equal to or higher than the curing temperature of the coating agent after the coating agent is injected. It is preferable.

  The injection pressure of the coating agent is not particularly limited, but is preferably 1 to 50 MPa, more preferably 3 to 30 MPa, and particularly preferably 5 to 22 MPa. If the pressure is too low, the coating material may not penetrate sufficiently. On the other hand, if the injection pressure is too high, the equipment cost will be excessive and the mold structure will need to be pressure resistant, making it less economical. There is sex.

In the in-mold coating method of the present invention, for all the points in the coating agent coating space, the shortest of the flow distances from that point to each coating agent inlet (hereinafter simply referred to as “minimum flow distance”). Is required to be 1.3 m or less. That is, if there are five coating agent inlets, the distance from one point in the coating agent application space to each coating agent injection port can be five long or short, but the shortest of them is 1.3 m or less. It is necessary to be. In other words, it is necessary that all points in the coating material coating space be at a flow distance of 1.3 m or less from any coating material injection port. The minimum flow distance is preferably 1 m or less, and more preferably 0.75 m or less. When the minimum flow distance exceeds 1.3 m, a portion where the coating agent does not reach occurs and a coating defect occurs.
The smaller the minimum flow distance (that is, the larger the number of injection ports when the application area is constant), the easier the coating of the coating material will be, but the mold structure will be more complicated, and more than one When the coating agent injected from the inlet collides, bubbles are generated and a coating defect is generated. Therefore, the minimum flow distance is preferably 0.05 m or more.

  Here, the flow distance is not a linear distance from one point in the coating agent coating space to each coating agent inlet, but the coating agent actually flows from each coating agent inlet to one point in the coating agent coating space. The distance that should be said. Therefore, when there is an obstacle on the flow of the coating in the coating application space, for example, a burr part for installing the opening of the molded body, the coating is prevented from flowing at the burr part and on the opposite side of the burr part. In order to reach the coating material, it is necessary to flow around this obstacle, so the flow distance increases.

  The attachment position of the coating agent inlet is determined in consideration of the mold structure and the flow of the coating agent. Since the flow rate of the coating agent is generally inversely proportional to the distance from the coating agent injection port, the coating agent can be injected more effectively by providing a plurality of injection ports. The number of inlets is not particularly limited.

  When multiple coating agent injection ports are provided, the coating agent can be injected simultaneously from all the injection ports, but if the flow rate at the paint bonding site is antagonized, bubbles often form at the bonded portion. It is not preferable. The coating agent can be injected evenly by adjusting the paint flow rate and the paint injection timing at each injection port in consideration of the paint flow.

  After injecting the coating agent, the coating agent is cured by being held at a predetermined temperature for a predetermined time. The curing temperature of the coating agent is preferably 70 to 110 ° C., more preferably 80 to 100 ° C., and the curing time is preferably 20 seconds to 6 minutes, more preferably 60 seconds to 4 minutes. If the curing temperature is too low, there is a risk that the coating agent will not be sufficiently adhered to the surface of the molded body and the coating agent may be peeled off. Conversely, if the curing temperature is too high, the coating agent will begin to cure while the coating agent is being injected. In addition to not being able to inject the agent to every corner, the injection pressure may become higher and the injector and mold may be damaged. If the curing time is too short, the coating agent may be insufficiently cured and the coating may be peeled off. On the other hand, if the curing time is too long, the productivity may decrease.

After the coating agent is cured, the mold is completely opened and removed to obtain a molded body on which the coating film is formed. In the present invention, the size of the molded body is such that the coating agent surface area is 2 m ² or more. Moreover, the shape of a molded object is not specifically limited, It can be set as a desired shape.

  Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited thereto. In the following, “part” is based on weight unless otherwise specified.

[Example 1]
(Mold and molding material)
In four locations of a female die of a forged aluminum male die and an electroformed female die for forming a front engine cover (hereinafter referred to as a “track cover”) of a truck (automobile). As shown in FIG. 1, coating agent injection ports (A, B, C, and D) were installed, and an injector having a maximum injection pressure of 40 MPa was attached to each coating agent injection port. FIG. 1 is a plan view of the track cover, in which the opening A is in the upper flat portion of the track cover, the openings B and C are in the side surface of the track cover, and the opening D is in front of the track cover. Located on the side. In the figure, an “opening” is an opening on the front surface of the track cover. In addition, a slide pin for forming a burr was installed in the male mold (not shown). This slide pin not only forms a burr, but also functions as a means for fixing the molded body as disclosed in International Publication No. 2005/046958. The mold fixing means has a locking structure on the dividing surface side of the female mold, in which a pin can protrude and retract from the wall surface. A core-sheath structure having a slide mechanism was used to make the pin retractable.
As a reaction stock solution component for reaction injection molding, solution A: a solution containing dicyclopentadiene as a main component and a polymerization catalyst component (product name “Meton T02A solution” manufactured by RIMTEC), solution B: dicyclopentadiene as a main component And a solution containing a catalyst activating component (manufactured by RIMTEC, trade name “Meton T02B solution”) and a coating agent (paint mainly composed of urethane acrylate oligomer: trade name “Praglas # 400”, manufactured by Dainippon Paint Co., Ltd.) To 100 parts, a paste consisting of 1 part of dibutyl phthalate and 1 part of bis- (4-t-butylcyclohexyl) peroxydicarbonate (trade name “Perkadox 16” manufactured by Kayaku Akzo Co., Ltd.) is mixed, and 130 ppm of benzoquinone is added. Additions] were used. The viscosity of the obtained coating material at 30 ° C. measured with a B-type viscometer No. 5 rotor 20 rpm 2 minutes after the start of rotation was 3,700 mPa · s. The viscosity of the coating material was adjusted to 3,000 mPa · s using a diluent made by Dainippon Paint.

(Forming and forming coating film)
The male mold and the female mold are clamped, the slide pin is in the “projecting” state, the female mold and the male mold are heated to 40 ° C. and 90 ° C., respectively, and the pressure is 0.49 MPa per area of the molded body. The mold was clamped, and using a reaction injection molding machine, equal weight solution A and solution B were collided and mixed in a mixing head, and the resulting reaction stock solution was poured into the mold. After filling the reaction stock solution, the mold temperature was maintained for about 1 minute.
Next, 1,490 mL of the coating agent was injected from the coating agent inlets A to D under the conditions shown in Table 1, respectively, and held at the mold temperature for about 3 minutes.
Thereafter, the slide pin was set in the “retracted” state, the mold was opened, and the track cover molded body having the coating film was taken out. When the design appearance of the track cover molded body was visually observed, the coating state of the coating film had no defects on the entire inner surface, and was covered at all portions with a thickness of 100 to 300 μm.
(Confirmation of coating material arrival position from each inlet)
In order to examine the arrival position of the coating material from each injection port, a different dye was mixed with the coating material injected from each injection port, and a coating experiment similar to the above was performed. Thereby, the position where the coating agent from each injection port collided was shown linearly as a boundary line of regions of different colors. The results are shown by broken lines in FIG.

[Comparative Example 1]
A track cover molded body was obtained in the same manner as in Example 1 except that the viscosity of the coating agent was not adjusted and the coating agent was used as it was at 3,700 mPa · s, and the coating agent injection pressure was doubled. When the design appearance of the track cover molded body was visually observed, there was a non-painted portion in the shaded area in FIG.

[Comparative Example 2]
A track cover molded body was obtained in the same manner as in Example 1 except that the addition amount of benzoquinone was 50 ppm and the curing start time of the coating agent was 55 seconds. When the design appearance of the track cover molded body was visually observed, a non-painted portion was present in substantially the same manner as the shaded portion in FIG.

[Comparative Examples 3 to 5]
A track cover molded body was obtained by operating in the same manner as in Example 1 except that the injection site and the injection amount of the coating agent were changed as shown in Table 1. In Comparative Examples 3 to 5, the coating agent was not injected from the injection ports A, B, and D, respectively. When the design appearance of the track cover molded body was visually observed, there was a non-painted portion indicated by hatching in FIGS. 2 (b) to 2 (d), respectively.

From the results shown in Table 1, when the viscosity of the coating is higher than the range specified in the present invention (Comparative Example 1) or the curing start time of the coating at 90 ° C. is shorter than the range specified in the present invention. When (Comparative Example 2), it can be seen that a coating defect occurs.
In addition, even when the viscosity of the coating material and the curing start time at 90 ° C. are within the range defined by the present invention, when there is a portion where the minimum flow distance exceeds 1.3 m (Comparative Examples 3 to 5), It can be seen that a coating defect occurs in the portion.
On the other hand, when the viscosity of the coating agent and the curing start time are within the range defined by the present invention and the minimum flow distance is 1.3 m or less for all points in the coating agent coating space, It can be seen that no coating is obtained (Example 1).

It is a figure (plan view) which shows the position (broken line) where the coating agent inject | poured from each injection port and the position (AD) of the coating agent injection hole in the metal mold | die used in Example 1, and collided. In the figure, the line segment indicates the distance from the coating agent inlet. The figure which shows the part (shaded part) which produced the application | coating defect in each comparative example. (A) The figure which shows the application | coating defect part in the comparative examples 1 and 2. FIG. (B) The figure which shows the application | coating defect part in the comparative example 3. FIG. (C) The figure which shows the application | coating defect part in the comparative example 4. FIG. (D) The figure which shows the application | coating defect part in the comparative example 5. FIG.

Explanation of symbols

  AD: Position of the injection port in the mold used in the examples and comparative examples

Claims (4)

Subsequent to resin molding in which a resin material is injected into a cavity formed by a male mold and a female mold, a mold is provided in the coating space for coating formed by the resin molded body and the mold. In the in-mold coating method in which a coating agent is injected from the coating agent injection port to form a coating layer on the surface of the resin molded body, (1) the coating surface area of the resin molded body is 2 m ² or more; (2) Using a coating agent having a curing start time at 90 ° C. of 60 seconds or more and 200 seconds or less and a viscosity of 3,500 mPa · s or less, and (3) for all points in the coating material coating space, An in-mold coating method, wherein a coating agent injection port is provided so that a shortest flow distance from a point to each coating agent injection port is 1.3 m or less.   The in-mold coating method according to claim 1, wherein the coating agent contains 0.06 to 2% by weight of an antioxidant.   The in-mold coating method according to claim 1, wherein the resin molding is reaction injection molding.   The covering molded object obtained by the in-mold coating method in any one of Claims 1-3.

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