KR100399302B1 - Resin-Coated Metal Sheet with Good Workability and Heat Resistance - Google Patents

Abstract

To provide a resin-coated metal sheet which satisfies workability, corrosion resistance, scratch resistance, and paintability, and exhibits stable heat resistance even when the final coating film and the silk printing layer are formed under high temperature baking conditions. for,

A resin coated metal plate having excellent processability and heat resistance, in which a resin coating layer containing an organic lubricant is formed on the surface of the metal plate, wherein the resin coating layer has at least one of active hydrogen or a functional group in the molecule for forming the resin coating layer, At least one crosslinking agent capable of crosslinking with the Rex resin is used, and in addition to the organic lubricant, at least the matrix resin and the unreacted crosslinking agent, a crosslinking agent of a different kind from the unreacted crosslinking agent, The reactant with the matrix resin is included.

Description

Resin-Coated Metal Sheet with Good Workability and Heat Resistance}

The present invention relates to a resin-coated metal sheet excellent in workability and heat resistance.

Conventionally, metal plates, especially zinc-plated steel sheets, used for home appliances, OA equipment, and building materials, require characteristics such as corrosion resistance, paintability, anti-fingerprint, silk printability, and the like. (scratch resistance) and the like must also have excellent characteristics. To this end, a conventional resin coated steel sheet which has been subjected to chromate treatment after galvanizing and has formed a resin coating layer has been used.

In this case, a conventional resin coating layer is usually blended with an organic resin, which is a matrix having a functional group, and a crosslinking agent, so that high curing degree and densification of the coating layer are achieved by crosslinking. In addition, silica and the like have been added to impart corrosion resistance, scratch resistance, and the like, and organic lubricants have been added to increase workability and lubricity. On the other hand, as an organic lubricant (wax), the compound which has a softening point of 80-140 degreeC according to the mold temperature at the time of processing has been used.

On the other hand, coating property (adhesiveness with the coating film according to post-painting or adhesion with the coating film by silk printing) is so good that there are many unreacted functional groups which do not react with the said crosslinking agent in the said resin coating layer. This is attributable to the reaction of the crosslinking agent contained in the after-paint coating with the unreacted functional group in the resin coating layer. In the case of the resin coating layer containing the organic lubricant (wax), since the organic lubricant has little functional group, the lower the content, the better the paintability. Therefore, conventionally, the amount of crosslinking agent in the resin coating layer is adjusted to balance the amount of organic lubricant while remaining unreacted functional groups in the matrix resin, thereby satisfying the contrary performances of workability, lubricity and paintability. Has been made.

On the other hand, in the above-described post-coating or silk screen printing, the final cured coating film was conventionally obtained at a baking time of about 130 to 160 ° C. and about 20 to 30 minutes. However, in recent years, there has been a tendency to obtain a final cured coating film by a high temperature short time baking (about 1 to 5 minutes before and after 200 ° C.) for high efficiency. By the way, when the baking temperature is exposed to 200 ° C. or higher, even if the matrix resin in the resin coated layer is crosslinked in the conventional resin coated steel sheet, if the degree is low, the softening and dissolving action of the wax is applied and the resin coated layer itself is softened. I found that throwing away happened. In this way, when the resin coating layer is softened, depending on the conditions, the finish of the final cured coating film adversely affects the appearance, and the adhesion between the resin coating layer and the metal plate or the cohesion force inside the resin coating layer is lowered. It is known that a problem arises in that the final cured coating film is peeled off from the metal plate for each resin coating layer. That is, in the final cured coating film forming step, in order to obtain a cured coating film with good finish appearance and good adhesion, it is concluded that the heat resistance of the resin coating layer should be improved.

In order to improve heat resistance, the amount of the crosslinking agent added to the matrix resin is increased in advance, the coating layer is further hardened and densified, and the amount of the organic lubricant which causes one of the lowering of the coating film strength at high temperature is greatly increased. It is also possible to reduce, but there is a possibility of causing a problem in workability. If the coating layer is highly crosslinked by increasing the amount of the crosslinking agent while keeping the amount of the organic lubricant (wax) constant, the heat resistance is somewhat improved, but instead, it is difficult to maintain the balance between the amount of the crosslinking agent and the lubricant. In the resin coating layer, the unreacted functional groups capable of reacting with the crosslinking agent in the coating material for the final coating film may be insufficient, resulting in deterioration of the coating property. In this way, workability (lubrication) and heat resistance are generally opposite characteristics, and therefore, compatibility thereof is required.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described points, and satisfies the corrosion resistance, coating property, scratch resistance, and workability of conventional resin coated steel sheets, and the final coating film formation and curing of the silk printed layer are carried out at high temperature baking conditions ( The object of this invention is to provide a resin coated metal sheet having excellent heat resistance, which can exhibit excellent coating properties and the like, and a method of manufacturing and using the same.

1 is a model diagram of a DTA chart for explaining the crosslinking reaction initiation temperature.

The resin coated metal sheet excellent in workability and heat resistance of the present invention includes a matrix resin and an matrix having a resin coated layer having at least one of active hydrogen and a functional group, that is, one or both of active hydrogen and a functional group. It consists of 2 or more types of crosslinking agents and an organic lubricant which can crosslink with resin. Here, as a crosslinking agent, the 1st crosslinking agent which reacts with the said matrix resin, as well as the 2nd crosslinking agent which reacts with the said matrix resin are comprised. Here, the second crosslinker starts to react with the matrix resin at a higher temperature than the first crosslinker.

The aforementioned configuration allows the matrix resin to carry out the crosslinking reaction in two steps. In the first step, the first crosslinking agent causes a crosslinking reaction to the extent that the resin coating layer has sufficient scratch resistance in the subsequent step, and in the second step (baking at a high temperature for a short time), the matrix resin is the first step. The second crosslinking agent left unreacted at reacts with the matrix resin to give a densely crosslinked resin layer to withstand softening by heat. This makes it possible to make workability and heat resistance compatible with each other.

The temperature at which the crosslinking reaction starts should be started at 130 ° C. or lower for the first crosslinking agent and 135 ° C. or higher for the second crosslinking agent. The combination of low-temperature crosslinking epoxy resin (first resin) and melamine resin (second resin) is suitable. It is very important that these two crosslinkers differ in temperature at the start of the crosslinking reaction.

According to the present invention, a resin-coated metal sheet having good processability and heat resistance is characterized in that the resin-coated layer has a first resin capable of reacting with a matrix resin, an organic lubricant, and the matrix resin having any or all of active hydrogen or functional groups in a molecule thereof. A crosslinking agent and a second crosslinking agent that can also react with the matrix resin, wherein the first crosslinking agent appears in the form of a reaction with the matrix resin, and the second crosslinking agent substantially does not interact with the matrix resin. It appears as a response form. It can be seen that this configuration takes advantage of the fact that the two crosslinkers react at different temperatures from the matrix resin or in the same way as the first crosslinker reacts with the matrix resin.

The resin-coated metal sheet described above is characterized in that the resin-coated layer contains the reaction product of the matrix resin, and before that, the first crosslinking agent performs baking in a short time at a high temperature. Resin-coated metal sheets at this stage are also within the scope of the present invention. The preferred condition is that the first crosslinker remains substantially intact without reacting with the matrix resin prior to baking at high temperature for a short time. Even in this state, the resin coating layer has good scratch resistance during fabrication. Another preferred state is that the second crosslinking agent remains substantially at 1 to 20% by mass without reacting with the matrix resin before being calcined at high temperature for a short time. This resin coating layer must be in this state to effectively prevent softening due to the crosslinking reaction in the baking step by the first crosslinking agent.

The resin coating layer described above optionally contains silica. It is preferable that the above-mentioned organic lubricant contains 0.5-20 mass% in the resin coating layer as much as possible.

The present invention also relates to a method for producing a resin coated steel sheet having good workability and heat resistance. The method comprises a coating step of a metal plate having a component for forming a resin coating layer, which component can crosslink and react with a matrix resin having either or both active hydrogen and functional groups in its molecule. And at least two kinds of crosslinking agents and organic lubricants, wherein the coated metal sheet is treated under conditions in which one of the crosslinking agents reacts with the matrix resin and the other crosslinking agent does not react with the matrix resin.

The present invention also relates to a method for producing a resin coated steel sheet having good processability and heat resistance, the method comprising a method of applying a resin metal sheet having a composition for forming a resin coated layer.

That is, the manufacturing method of the resin-coated metal plate excellent in the heat resistance of this invention is a matrix resin which has any or all of active hydrogen and a functional group in a molecule | numerator, 2 or more types of crosslinking agents which can crosslink and react with this matrix resin, and organic After applying the composition for forming a resin coating layer containing a lubricant on a metal plate, the crosslinking agent of the crosslinking agent lower than the crosslinking reaction initiation temperature of the crosslinking agent having the highest crosslinking reaction temperature among the crosslinking agents contained in the composition and having the lowest crosslinking reaction initiation temperature It heat-drys at temperature higher than reaction start temperature, and it is a summary that in this heat-drying process, crosslinking reaction of the crosslinking agent with the highest crosslinking reaction start temperature and matrix resin does not arise substantially. Suitable temperatures in the heat drying step are 80-120 ° C.

In the present invention, when a coating film, i.e., a coating film according to silk printing, is formed on the surface of the resin coating layer by a method of using a resin coated metal plate, a reaction between the unreacted crosslinking agent remaining in the resin coating layer and the matrix resin occurs. It also includes a method of using a resin-coated metal sheet characterized in that it is heated to a sufficient temperature. Such coating methods also fall within the scope of the present invention.

Embodiment of the Invention

In the resin coated metal sheet of the present invention, a resin coated layer is formed on at least one surface of the metal sheet. Since the resin coating layer is already crosslinked with one crosslinking agent, even if it is stored in the state of the out-of-print product or the coil product, there is no stickiness or blocking property of the coating layer, that is, the coating surface. In addition, since the first crosslinking system has an appropriate hardness and at the same time contains an organic lubricant, it is also excellent in corrosion resistance and scratch resistance, and causes processing scratches on the surface of the coating during molding (slit processing, punching, drilling, etc.). I never do that. In addition, since the moderate amount of unreacted functional groups remain in the matrix resin in the resin coating layer, the coating property in the case of being thick-coated (130 to 160 ° C. for about 20 to 30 minutes) under conventional conditions is also good.

In addition, in the case where hardening of the final coating film (including the coating film according to silk printing) is performed at a high temperature for a short time, not other conventional coating conditions, other crosslinking agents remaining in the resin coating layer by unreacted before baking is carried out. When baking, the second cross-linking system is rapidly progressed by reacting with the matrix resin to prevent softening of the resin coating layer, thereby improving heat resistance, and excellent adhesion between the resin coating layer, the metal plate, the resin coating layer, and the baking coating film, respectively. Moreover, the external appearance of the baking coating film was able to be completed favorably. Hereinafter, the present invention will be described in detail.

The matrix resin is not particularly limited as long as it has at least one active hydrogen or functional group capable of reacting with a crosslinking agent. However, the modified polyolefin resin, polyurethane resin, acrylic resin, epoxy resin, polyester resin Etc. are exemplified as being good, and these may be used alone or in combination of two or more if compatibility is good. It is preferable to use these resins in water dispersion or water-soluble thing for environmental protection. In view of workability, scratch resistance and paintability, a modified polyolefin resin and a polyurethane resin are suitable, and in consideration of corrosion resistance, a modified polyolefin resin is most suitable.

The modified polyolefin-based resin is modified in order to have a functional group, and in particular, since ionization can be achieved, a polyolefin-based resin having a carboxyl group as a functional group is suitably used (modified polyolefin resin has an ionic group when it has a carboxyl group). Become possible). This function is used to polymerize olefins of olefins (such as ethylene, propylene, butene, etc.) and ethylenically unsaturated carboxylic acids ((meth) acrylic acid, maleic acid, fumaric acid, itaconic acid, etc.) and other monomers copolymerizable with them as necessary. You can get along. In order to adjust the quantity of the carboxyl group which is a functional group, it is preferable to set 1-40 mass% as ethylenic unsaturated carboxylic acid in 100 mass% of monomers. When there is less carbonic acid than 1 mass%, functional groups are too small to achieve the objective of this invention, and water dispersion for environmental protection is difficult, and it is not preferable. On the contrary, when the carboxylic acid exceeds 40% by mass, the modified polyolefin-based resin will form a resin coating layer having poor corrosion resistance and water resistance. On the other hand, ethylene is most suitable as olefin, and (meth) acrylic acid is most suitable as unsaturated carboxylic acid.

As another copolymerizable monomer, (meth) acrylic-acid alkylesters, such as methyl (meth) acrylate, ethyl (meth) acrylate, and (meth) acrylic acid propyl; Aromatic monomers such as styrene, α-methylstyrene, chlorostyrene and vinyltoluene; Hydroxyl group-containing (meth) acrylic acid esters such as hydroxyethyl (meth) acrylate and hydroxylpropyl (meth) acrylate; Amide monomers such as N-methylol (meth) acrylamide; Epoxy group-containing (meth) acrylic acid esters such as glycidyl (meth) acrylate; (Meth) acrylonitrile; 1 type, or 2 or more types, etc. can be combined and used for them. Since a hydroxyl group, an amide group, an epoxy, etc. are functional groups which can react with a crosslinking agent, the crosslinking agent which has a functional group which reacts with these functional groups can also be used.

It is preferable to use the carboxyl group-containing polyolefin resin obtained in this way by water dispersion (emulsification) and ionization using alkalis and anions, such as aqueous ammonia. The anion is preferably a metal ion, and may include lithium, sodium, potassium, magnesium, calcium, aluminum, and the like, in particular sodium ion. By ion crosslinking, the corrosion resistance and scratch resistance of the resin can be improved.

Polyurethane resin has active hydrogen derived from hydroxyl group and amino group

. As the polyurethane resin, commercially available water dispersions such as "Superflex" (manufactured by Daiichi Kogyo Pharmaceutical Co., Ltd.) may be used, and water dispersions obtained by the following various known methods may also be used.

(1) A solution of so-called urethane prepolymers having isocyanate groups at both ends with amino or hydroxyl groups and sulfonic acid groups or carboxyl groups, such as alkali or ammonium salts of giaminocarboxylic acids. And a method of emulsifying at the same time as the chain extension.

(2) A method of dispersing a polyol compound, a compound having a quaternary ammonium group and a hydroxyl group in the molecule, a compound having an epoxy group and a hydroxyl group in the molecule, and the like by dispersing it in water.

(3) A polyester polyol or a polyol, an aromatic polyisocyanate, or an aliphatic diisocyanate and a chain extender are reacted with each other in an inert organic solvent, and the reaction product is added organically by adding water containing an appropriate amount of a lactic agent. Method of distilling off solvent after stirring. Herein, polyol compounds such as polyether, polyethylene glycol, polypropylene glycol, butanediol and hexanediol, such as tetrahydrofuran, ethylene oxide, and propylene oxide, and maleic acid and cohark Polyester polyols are obtained by dehydration condensation with dicarboxylic acids such as succinic acid and adipic acid, and polyols are polyesters obtained by ring-opening polymerization of cyclic esters. , Polyacetal, polyester amide, polythio ether. Aromatic polyisocyanates are represented by 1,5-naphthalene diisocyanate, 4,4 diphenylmethane diisocyanate (MDI), phenylene diisocyanate, xylene diisocyanate and toluene diisocyanate (TDI), and the aliphatic diisocyanate is hexamethylene di. And isocyanate and dicyclohexyl methane diisocyanate. The chain extender is represented by low molecular weight diamines such as ethylenediamine, propylenediamine, diethylenetriamine, hexamethylenediamine and xylenediamine and the polyol compound, and the inert organic solvent is tetrahydrofran, acetone, methyl ethyl ketone, It is represented by ethyl acetate, toluene, etc.

(4) Polyurethane urea polyamine, such as diethylene triamine, is reacted with a urethane prepolymer having both terminal isocyanate groups to obtain a polyurethane urea polyamine, or an aqueous solution of an acid is added thereto or the poly After impregnating epichlorohydrin with urethane urea polyamine, an aqueous solution of an acid is added thereto.

(5) A method in which a basic aqueous solution is mixed after reacting a cyclic dicarboxylic acid anhydride with the polyurethane urea polyamine, an alkyl isocyanate imide, or an epihalohydrin impregnation.

(6) reacting the polyurethane urea polyamine or its epihalohydrin impregnated with sulfonic acid, lactonic acid or sodium monohalogenated carbonate, or with (meth) acrylic acid ester acrylonitrile or the like. Hydrolysis, followed by mixing with water.

(7) After dispersing the terminal amino group compound obtained by reacting diamines with a terminal hydroxyl group or a urethane prepolymer having an isocyanate group obtained from a polyol and a polyisocyanate, using an emulsifier, High molecular weight by adding polyisocyanate again.

As an acrylic resin, hydroxyl group containing (meth) acrylic acid ester, such as carboxyl group-containing (meth) acrylic acid, (meth) acrylic-acid hydroxyethyl, and (meth) acrylic-acid hydroxypropyl; Amide monomers such as N-methylol (meth) acrylamide; Epoxy-group-containing (meth) acrylic acid esters, such as (meth) glycidyl acrylate, are selected arbitrarily 1 type, or 2 or more types, and (meth) acrylic acid, such as methyl (meth) acrylate, ethyl (meth) acrylate, and propyl (meth) acrylate Alkyl esters; Aromatic monomers such as styrene, α-methylstyrene, chlorostyrene and vinyltoluene; By polymerizing one kind or two or more kinds of (meth) acrylonitrile and the like as necessary, an acrylic resin containing a carboxyl group, a hydroxyl group, an amide group or an epoxy group as a functional group is obtained.

As the epoxy resin, a known epoxy resin having an epoxy group as a functional group can be used. As polyester resin, what has functional groups, such as a carboxyl group and a hydroxyl group, is preferable, Glyphtal resin, a phthalic acid resin, an isophthalic acid resin, maleic acid resin, aliphatic polyester resin, oxy acid Oxyacid resins and the like are available.

In this invention, two or more types of crosslinking agents must be used in order to form a resin coating layer. In addition, the resin coating layer of the resin coated metal sheet of the present invention, in addition to the organic lubricating agent which is an essential component to be described later, at least the above-mentioned matrix resin that reacts differently, unreacted crosslinking agent, two kinds of crosslinking agents different from the unreacted crosslinking agent, and The reactants with the matrix resin need to be included. In other words, after heating and drying, the resin coating layer should include the matrix resin crosslinked with the first crosslinking agent and the remaining unreacted second crosslinking agent activated only at the subsequent high temperature burnt part until the high temperature burnout. The matrix resin does not always need to be fully crosslinked. Part of the matrix resin remains intact since the first crosslinking agent is not always added in excess. Since the crosslinking reaction of the matrix resin has already been carried out with the first crosslinking system, there is a "reactant of the crosslinking agent with the matrix resin," which is generated. The reaction crosslinking agent must exist. Again, the matrix resin may be a reactant with the crosslinking agent used in the first crosslinking system, that is, a part of the functional group of the matrix resin may be a reactant with the crosslinking agent. Since the crosslinking agent is not added in a large amount, the matrix resin itself which does not react with the crosslinking agent at all may be included in the resin coating layer.

With this configuration, the small coating of the high temperature and short time is appropriately crosslinked with the first crosslinking system, and on the other hand, the resin coating layer containing the organic lubricant exhibits good workability, corrosion resistance, scratch resistance and paintability. In addition, since the second cross-linking system advances in the resin coating layer and softening of the resin coating layer itself is suppressed by heating in the baking process of a high temperature and short time, a uniform final hardened coating film is formed on the surface of the resin coating layer, thereby achieving a good finish. A painted surface is obtained. In addition, since the dense crosslinking reaction of the matrix resin proceeds in the resin coating layer, the movement of the molten organic lubricant is also hindered, and the interfacial adhesion between the surface of the metal plate and the resin coating layer or the cohesion in the resin coating layer is also reduced. Disappear.

As described above, in order to react the first crosslinking system and the second crosslinking system separately, a method such as dividing the initiation method of the crosslinking reaction into heat and an electron beam can be considered.

However, in the case of the final high-temperature short-time baking, the second crosslinking system is performed with a high temperature reactive crosslinking agent by using about 200 ° C heat, and in the first crosslinking system, the second crosslinking system reacts. It is the most preferable method to cause crosslinking reaction at low temperature which a crosslinking agent cannot react.

For this reason, in the present invention, in order to form the resin coating layer, at least two types of crosslinking agents having different crosslinking reaction start temperatures with the matrix resin are used, and the crosslinking agent having the highest crosslinking reaction start temperature is used as the second crosslinking agent and the crosslinking reaction start. When the crosslinking agent having the lowest temperature is used as the first crosslinking agent, the resin coating, which is heated and dried but has not yet been hot baked, contains the reactant of the matrix resin and the first crosslinking agent and an unreacted second crosslinking agent. In a preferred embodiment of the present invention, a structure substantially free of the reactant of the matrix resin and the second crosslinking agent and the unreacted first crosslinking agent is provided.

That is, the first crosslinking system is first performed with the first crosslinking agent having the lowest crosslinking reaction starting temperature, and the second crosslinking system is performed with the second crosslinking agent having the highest crosslinking reaction starting temperature. Thus, the resin coated layer metal sheet of the present invention (before being baked in the final high temperature short time) has a reactant produced after the reaction between the first crosslinking agent and the matrix resin, and the second crosslinking agent unreacted with the matrix resin. It will be included. In other words, even after drying under heat, the reactant of the matrix resin and the second crosslinking agent and the unreacted first crosslinking agent are not contained in the resin coating layer until the hot baking is started. However, it is conceivable that the second crosslinking agent reacts with the matrix resin or the first crosslinking agent remains unreacted in the first low-temperature crosslinking system. The technical idea of this invention does not exclude that this etc. is included but it means "it does not contain substantially." As described above, the matrix resin itself, which does not react with any crosslinking agent, or the reactant of the matrix resin with the first crosslinking agent and the second crosslinking agent, and the reactant with the first crosslinking agent and the second crosslinking agent. It can be considered that such as is also included, but these are not excluded.

Here, the initiation temperature of the crosslinking reaction is determined by the mixture of the matrix resin and the crosslinking agent on the differential thermal analyzer (made of film developability at room temperature). That is, the crosslinking reaction initiation temperature is mixed with the matrix resin and the crosslinking agent and coated at room temperature, and heat is applied to the obtained film by using a differential thermal analysis (DTA) apparatus, and the matrix resin and the crosslinking agent start the reaction. Is the temperature at which the exothermic reaction began to occur. 1, the model diagram of the DTA chart obtained by the differential thermal analysis apparatus, and the crosslinking reaction start temperature are shown.

The second crosslinking agent having a high crosslinking reaction start temperature may vary depending on the crosslinking reaction initiation temperature of the first crosslinking agent and the temperature of the final coating film forming step. However, the second crosslinking agent preferably has a crosslinking reaction initiation temperature of 135 ° C. or higher, for example, a melamine coefficient. Branches and blocked isocyanates can be used. The melamine resin reacts with hydroxyl groups, carboxyl groups, hydroxyl groups in urethane, active hydrogens, epoxy groups and the like. For example, "Summer M40W", "Sumima M50W" (both manufactured by Sumitomoto Chemical Co., Ltd.) and "Simell 303" (manufactured by Mitsui Scitech Co., Ltd.) are available.

Block isocyanate blocks active isocyanate with an active hydrogen-containing compound (blocking agent), and volatilizes the blocking agent by heating to activate. This block isocyanate can also be used as a 1st crosslinking agent with a low crosslinking reaction start temperature. That is, the thermal dissociation temperature of a blocking agent can be controlled by selecting suitably the kind of blocking agent which blocks the active isocyanate group of polyisocyanate compounds, such as TDI and MDI. When aliphatic alcohol-based blocking agents such as methanol, ethanol, and butyl cellosolve are used, the thermal crosslinking temperature is high (some may exceed 180 ° C), and the second crosslinking agent is preferably used when a high temperature baking process is performed. Lactam systems, such as (epsilon) -caprolactam, following an alcoholic blocking agent; Phenol type, such as phenol and cresol; Oximes such as methyl ethyl ketoxime and cyclohexane oxime; Activated methylene systems such as dimethyl malonate and ethyl aceto hexaacetate; In this order, the blocking agent may lower the thermal decomposition temperature (down to about 110 ° C), and may appropriately select the second crosslinking agent and the first crosslinking agent in consideration of the temperature during the crosslinking reaction.

As a 1st crosslinking agent with a low crosslinking reaction start temperature, the crosslinking agent which has a crosslinking reaction start temperature of 130 degrees C or less is suitable. In this respect, a low temperature crosslinking agent type epoxy resin can also be used favorably. An epoxy group reacts with active hydrogens, such as a hydroxyl group, a carboxyl group, and an amine. Specifically, "EX-313", "EX-314", "EX-321", "EX-421", "EX-512", "EX-521" of "Dena call series (made by Nagase Chemical Co., Ltd.)" EX-147 "," EX-810 "," EX-313 ", etc.," Lica Bond EX-8S "," Lica Bond AP-355B "(all made by Chuo Chemical Co., Ltd.), etc. are available.

Moreover, if the objective of this invention is not impaired, you may use together the other crosslinking agent which has a crosslinking reaction start temperature between a 1st crosslinking agent and a 2nd crosslinking agent, and when carrying out 1st crosslinking suitably or 2nd What is necessary is just to make it react when carrying out bridge | crosslinking of. Examples of such other crosslinking agents include methirol compounds, amine compounds, high temperature crosslinking type epoxy resins, aziridinyl group-containing compounds and the like.

It is suitable that the 1st crosslinking agent and the 2nd crosslinking agent contain 1-20 mass% (solid content) in the resin coating layer, respectively. However, 30 mass% or less is suitable as a total amount. As the present state, it is ideal that the second crosslinking agent is substantially in the unreacted state with the matrix resin, and the first crosslinking agent is contained in the resin coating layer in a state in which the first crosslinking agent is reacted with the matrix resin.

If the second crosslinking agent is less than 1% by mass, the heat resistance of the resin coating layer is weakened, and softening of the resin coating layer at high temperature firing cannot be suppressed, which is not preferable. More preferably, it is 2 mass% or more. However, when the second crosslinking agent is more than 20% by mass, the amount of the second crosslinking agent for high temperature firing is too large and corrosion resistance is not preferable. On the other hand, when the first crosslinking agent is less than 1% by mass, corrosion resistance and scratch resistance are weakened, which is not suitable. However, if the content exceeds 20% by mass, the crosslinking reaction proceeds excessively in the first crosslinking system, so that the coating becomes hard, and the coating is broken during processing, thereby reducing the corrosion resistance. More preferable upper limit is 10 mass%.

Moreover, when the sum total (the total of all crosslinking agents when using other crosslinking agents together) exceeds 30 mass%, since corrosion resistance fall by residual crosslinking agent arises, it is unpreferable.

The organic coating agent is essentially contained in the resin coating layer of this invention. This is because it is necessary to secure the lubricity of the resin coating layer in the processing step and prevent scratches. It is preferable that 0.5-20 mass% is contained in the resin coating layer. If the amount is less than 0.5% by mass, the effect of improving workability and scratch resistance cannot be exhibited. If the content exceeds 20% by mass, the effect is saturated and the heat resistance of the baking step in post-coating and silk printing is lowered. Not desirable

As an organic lubricant, Polyolefin wax, such as polyethylene, polyethylene oxide, and a polypropylene; Fluorine resins such as polytetrafluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, and tetrafluoroethylene; Paraffin wax and the like can be used. In view of lubricity, polyethylene wax is suitable. In particular, spherical particles having an average particle diameter of 0.1 to 3 mu m are preferable. If it is less than 0.1 mu m, the effect of improving the scratch resistance is small, and if it exceeds 3 mu m, it is difficult to disperse uniformly in the resin coating layer. It is preferable that a softening point exists in the range of 80-140 degreeC, and below 80 degreeC, a wax will liquefy at the time of processing, and workability may be inferior. Moreover, when it exceeds 140 degreeC, lubricity will worsen.

As spherical polyethylene wax particles, "DIEJET E-17" (made by Koou Chemical Co., Ltd.), "KUE-1", "KUE-5", "KUE-8", (made by Sanyo Chemical Co., Ltd.), "Kemi" `` W-100 '', `` W-200 '', `` W-300 '', `` W-400 '', `` W-500 '', `` W-640 '', `` W-700 '', etc. And "Elephone E-20" (manufactured by Nikka Chemical Co., Ltd.) are available.

The resin coating layer may contain 5 to 30% by mass of silica in terms of solid content, and is effective for improving corrosion resistance and scratch resistance. When less than 5 mass%, this effect is hard to express, but when it exceeds 30 mass%, cracks may enter a resin at the time of the drying process at the time of resin coating layer formation, and since it leads to corrosion resistance fall, it is unpreferable.

The silica may be spherical particles or chains. In the case of spherical particles, the average particle diameter is suitably in the range of 1 to 200 nm. If the particle diameter is small, the corrosion resistance is improved because cracks do not enter, but if the particle size is too small, the stability of the resin coating-forming composition tends to be inferior. When too large, the film forming property of a resin coating layer may worsen. The range of a more preferable particle diameter is about 4-20 nm. As such silica particles, colloidal silica and fumed silica are suitable. For example, "XS", "SS", "" of the Snowtex series (colloid silica made by Nissan Chemical Co., Ltd.), " 40 "," N "," UP ", etc. can be used very suitably.

The resin-coated metal sheet of the present invention can be obtained by appropriately mixing the above components to prepare a composition for forming a resin-coated layer, applying it on a metal plate, and drying it. As for the composition for forming a resin coating layer, it is preferable to use an aqueous dispersion (or water-soluble) matrix resin as described above in order to protect the environment. Therefore, in the aqueous dispersion of the matrix resin, a crosslinking agent, an organic lubricant, and, if necessary, silica, are used. It can prepare by mix | blending and mixing. At this time, in the range that does not impair the object of the present invention, diluent solvent, anti-film peeling agent, leveling agent, antifoaming agent, penetrating agent, emulsifier, coating agent, coloring pigment, thickener (thi-ckner), silane coupling agent, functional group and activity You may add other resin etc. which do not have hydrogen suitably.

The metal plate is not particularly limited, and examples thereof include zinc or zinc-based plated steel sheets, aluminum plates, aluminum alloy plates, titanium plates, and the like. In forming the coating resin layer, chromate treatment or phosphate treatment is effective on improving the corrosion resistance and adhesion by providing the plating film or the surface of the metal plate. The chromate treatment may be any treatment method such as reaction type, coating type, or electrolytic type.

In order to form the resin coating layer on the metal plate, the composition for forming the resin coating layer is applied to one side or both sides of the surface of the metal plate using a known coating method, that is, a roll coating method, a spray method, a curtain flow coating method, or the like. Heat drying. The heat drying temperature needs to be applied at a temperature higher than the temperature at which the first crosslinking system proceeds, that is, at a temperature higher than the crosslinking reaction start temperature of the first crosslinking agent. However, as described above, in order to express heat resistance while maintaining paintability and workability, the second crosslinking system should be subjected to high temperature and short time baking in the final step. Therefore, in the heat drying step of forming the resin coating layer, It is preferable to dry at a temperature lower than the crosslinking reaction start temperature of the second crosslinking agent so that the second crosslinking system does not proceed. However, although the second crosslinking agent may partially react due to the custom of chemical reaction, it is not excluded from the resin coated metal sheet of the present invention as long as the unreacted second crosslinking agent remains.

The specific drying temperature may be determined in consideration of the crosslinking reaction initiation temperature of the first crosslinking agent and the second crosslinking agent, but when the spherical polyethylene wax is used as the organic lubricant, it is better to maintain the spherical shape in later processing steps. Since this becomes favorable, drying in the range of 70-130 degreeC is desired. Therefore, it is preferable to select the first crosslinking agent capable of crosslinking reaction in the temperature range, and in that sense, the use of a low-temperature crosslinking type epoxy resin is recommended. In consideration of the fact that the resin coating-forming composition is an aqueous medium, a more preferable heating and drying temperature is 80 to 120 ° C.

As for the thickness (adhesion amount) of the resin coating layer, after drying, 0.2-2.5 g / m <2> is suitable.

. If too thin, corrosion resistance and scratch resistance cannot be sufficiently exhibited, and if it exceeds 2.5 g / m 2

At the time of processing, the resin coating layer may peel off. Moreover, 0.4-1.5 g / m <2> is more preferable from a viewpoint of electroconductivity and weldability.

By forming a resin coating layer, the resin coating metal plate of this invention can be obtained. The resin-coated metal sheet may be used as it is after the processing step depending on the application, or may be used after coating and silk printing under conditions of 130 to 160 ° C. for about 20 to 30 minutes. In the coating and silk printing process under conventional conditions, the second crosslinking system proceeds for several minutes, so the corrosion resistance of the coating film obtained by these processes is good.

. Of course, the use of the final cross-linking system after the second cross-linking system is finally preferred by using a coating and / or silk printing process using a high-temperature short-time baking of about 1 to 5 minutes at around 200 ° C. . It is because it is possible to obtain a good final coating film of the appearance in a short time, since the resin-coated metal sheet excellent in heat resistance of the present invention can be exhibited. In the final high-temperature short-time baking step, the heating temperature of about 200 ° C is set. As the second crosslinking agent, it is necessary to select the crosslinking reaction to proceed rapidly at this heating temperature. The crosslinking reaction proceeds sufficiently. Melamine resins and high temperature dissociation type block isocyanates are especially suitable.

(Example)

The present invention will be described in more detail with reference to the following Examples, but the following Examples do not limit the present invention, and all modifications within the scope not departing from the spirit of the present invention belong to the present invention.

[Method of implementation]

The test method used in the following examples is as follows.

(1) Crosslinking reaction start temperature

The matrix resin and the crosslinking agent are mixed, coated on a tetrafluoroethylene plate and formed into a film at room temperature to obtain a dry coating film. About the obtained film, it heated using the DTA apparatus and obtained crosslinking reaction start temperature (degreeC) in the obtained chart as shown in FIG.

(2) pencil scratch test

The resin coating as it was dried at 80 ° C. for 1 minute, and high temperature short time baking (

On the resin-coated metal sheet obtained at 230 ° C. for 50 seconds, a pencil scraping test in accordance with JIS K5400 was performed, and the scratches were confirmed by lupa to evaluate the curing of the coating layer.

(3) Machinability

The resin coated metal sheet was subjected to a single press test using an 80 ton crank press apparatus, and the film surface state of the sliding surface after press molding was visually evaluated based on the following criteria. 5: Almost flawless, 4: Slightly flawless, 3: Clearly flawless, 2: Large flaw, 1: Breaking | breaking generate | occur | produced.

(4) corrosion resistance

The edge of the resin coated metal plate was sealed, and the salt spray test specified in JIS Z2371 was carried out to evaluate the corrosion resistance by the time until 1% of white blue was generated.

(5) heat resistance

Film after drying polyester coating on the resin coated metal plate by bar coating method

It applied so that thickness might be 20 micrometers, and baked at 230 degreeC for 50 second, and the baking coating was formed.

. After immersing the sample with the baking sheet in boiling water for 1 hour, take it out, and chopped the base wood into 100 pieces (10 × 10) at intervals of 1 mm with a cutter knife to perform a peeling test. Both sides of the are counted.

Example 1

As the metal plate material, an electrogalvanized steel sheet (Zn deposition amount of 20 g / m 2 and plate thickness 0.8 mm) was subjected to chromate treatment (Cr deposition amount of 15 g / m 2).

Ethylene-acrylic acid copolymer (20 mass% acrylic acid) emulsion was used as the matrix resin for the composition for resin coating formation. A part of the carboxyl group of the copolymer was ionized with sodium hydroxide and ion-crosslinked. Colloidal silica ("Snowtex 40") having a particle size of 10 to 20 nm and a spherical polyethylene wax having a softening point of 100 ° C. and an average particle diameter of 0.6 μm to 5% by mass in the solid content in the composition (manufactured by Nissan Chemical Co., Ltd.)

) Was blended into the emulsion so as to be 20% by mass in the solid content of the composition.

Furthermore, low-temperature cross-linked epoxy resins (`` Denacol EX-313 '': Nagase Chemical Co., Ltd .: crosslinking reaction temperature 50 ° C) and melamine resins (`` Seminal M40W '': Sumitomo Chemical Co., Ltd .: crosslinking reaction temperature 140 ° C) Was combined with the amount shown in Table 1 (mass in the composition) and stirred well.

Each composition was apply | coated to one side of the said metal plate with a roll, and it dried by heating for 1 minute at the temperature of 80 degreeC of board | plate, and obtained the resin coating metal plate of thickness (adhesion amount) 1g / m <2>. Each evaluation result is shown in Table 1.

Example 2

A resin-coated metal sheet was obtained in the same manner as in Example 1, except that an aqueous dispersion of polyurethane resin (“Superflex”: Daiichi Kogyo Pharmaceutical Co., Ltd.) was used as the matrix resin, instead of using an ethylene-acrylic acid copolymer. It was. The results are shown in Table 2.

In the resin coated metal sheet of the present invention, a resin coated layer is formed on at least one surface of the metal sheet. Since the resin coating layer is already crosslinked with one crosslinking agent, the first crosslinking system has a suitable hardness and at the same time contains an organic lubricating agent, which is excellent in corrosion resistance and scratch resistance and also excellent in slit processing. No processing defects occur on the surface of the coating during forming processing such as drilling and drilling. Moreover, since a suitable functional group remains in the matrix resin in the resin coating layer, the coating property in the case of post-coating (130-160 degreeC, about 20 to 30 minutes) on conventional conditions is also favorable.

In addition, in the case of forming a final coating film or forming a silk printing layer in a high-temperature short-time baking process, which is not a conventional baking condition, other residues remaining in the resin coating layer by unreacted before the baking process coating are applied. Since the crosslinking agent is reacted with the matrix resin when the baking is performed, the second crosslinking system proceeds, thereby preventing the softening of the resin coating layer and improving the heat resistance, and the adhesion between the resin coating layer, the metal plate, the resin coating layer and the baking coating film. Can make each of them excellent

. In addition, the appearance of the baked coating film can be satisfactorily completed.

Claims (15)

The resin coating layer of the resin coating metal plate having the resin coating layer formed on the metal surface Matrix resins having at least one of active hydrogen functional groups in a molecule; Organic lubricants; A first crosslinking agent capable of reacting with the matrix resin; A second crosslinking agent capable of reacting with the matrix resin and initiating a crosslinking reaction with the matrix resin at a temperature higher than the initiation temperature of the first crosslinking agent which initiates the crosslinking reaction with the matrix resin. Resin-coated metal sheet excellent in workability and heat resistance, characterized in that consisting of a. The resin-coated metal sheet having excellent workability and heat resistance according to claim 1, wherein the first crosslinking agent has a crosslinking start temperature of 130 ° C or lower, and the second crosslinking agent has a crosslinking start temperature of 135 ° C or higher. The resin-coated metal sheet having excellent workability and heat resistance according to claim 1, wherein the first crosslinking agent is an epoxy resin and the second crosslinking agent is a melamine resin. The resin coated metal plate as set forth in claim 1, wherein the resin coated metal plate includes a reactant of the matrix resin and the first crosslinking agent. The resin-coated metal sheet having excellent workability and heat resistance according to claim 4, wherein the resin coating layer does not substantially contain the first crosslinking agent without reaction with the matrix resin. The resin coated metal plate according to claim 1, wherein the resin coated layer contains substantially 1 to 20% by mass of the second crosslinking agent without reaction with the matrix resin. The resin-coated metal sheet excellent in workability and heat resistance according to claim 1, wherein the resin coating layer further comprises silica. The resin-coated metal sheet having excellent processability and heat resistance according to claim 1, wherein the resin coating layer contains 0.5 to 2.0 mass% of the organic lubricant. In the resin coated metal plate constituting the resin coating layer with good processability and heat resistance, the resin coating layer is Matrix resin which has at least any one of active hydrogen or a functional group in a molecule | numerator; Organic lubricants; A first crosslinking agent capable of reacting with the matrix resin; The first crosslinking agent is capable of reacting with the matrix resin, and the first crosslinking agent is composed of a second crosslinking agent which appears in a substantially intact state that does not react with the matrix resin, unlike the first crosslinking agent. Resin coated metal sheet. 10. The resin coated metal plate according to claim 9, wherein the resin coated layer does not substantially contain the first crosslinking agent without reaction with the matrix resin. 10. The resin coated metal plate according to claim 9, wherein the resin coated layer substantially contains 1 to 20% by mass of the second crosslinking agent when there is no reaction with the matrix resin. The method for producing a resin coated metal sheet having good processability and heat resistance A metal plate is coated to have a composition for forming a resin coating layer, the composition comprising at least one of a matrix resin having at least one of an active hydrogen or a functional group in the molecule, an organic lubricant, and at least one crosslinkable reaction with the matrix resin. Comprising a crosslinking agent; One of the crosslinking agents reacts with the matrix resin and the other of the crosslinking agents is treated with the coated metal plate under conditions that do not react with the matrix resin Method for producing a resin-coated metal sheet, characterized in that consisting of and ((法 方法). The method for producing a resin coated metal sheet having good processability and heat resistance A metal plate is coated to have a composition for forming the resin coating layer, and the composition is one of a matrix resin having at least one of active hydrogen or a functional group in a molecule, an organic lubricant and a crosslinkable reaction with the matrix resin. Applying said composition comprising at least a crosslinking agent onto said metal plate; Among the crosslinking agents contained in the composition, heat drying is performed at a temperature lower than the crosslinking reaction initiation temperature of the crosslinking agent having the highest crosslinking reaction temperature and higher than the crosslinking reaction initiation temperature of the crosslinking agent having the lowest crosslinking reaction initiation temperature. The method for producing a resin-coated metal sheet having excellent workability and heat resistance, characterized by heating and drying so as not to substantially cause a crosslinking reaction between the crosslinking agent having the highest crosslinking reaction temperature and the matrix resin.方法). The method of claim 13, wherein the heating and drying step is carried out at a temperature range of 80 to 120 ℃. 11. The method according to claim 9 or 10, wherein in order to further form a coating film on the surface of the resin coating layer, heating is carried out at a temperature sufficiently high so that a reaction between the unreacted crosslinking agent remaining in the resin coating layer and the matrix resin occurs. The manufacturing method of the resin metal plate to make.