JP5150385B2 - Two-component fast-curing resin composition - Google Patents

Description

  The present invention is a two-component blended acrylic urethane resin, especially when applied to top coats and base coats for repairing automobiles. Paper sharpening and compound finishing are possible in a short time after painting, shortening painting work time. The present invention relates to a two-component crosslinked resin composition having a technology that can be used and a technology that can delay the pot life after blending the two components.

JP 2002-53800 A

  In the field of automotive repair coating, paints using a two-component curable coating with a polyol component and a polyisocyanate component have improved coating properties within a shorter time after painting work in order to improve repair finish productivity. It is desired to express. That is, it is desired to complete the repair work quickly by finishing polishing and polishing in a shorter time after painting.

  In the case of the two-component paint, it is possible to accelerate the curing speed by the reaction catalyst and increase the speed of physical properties, but the catalytic effect is also limited. In other words, when excessively used tin-based or amine-based urethanization catalyst is added in excess, not only the curing speed is increased, but the paint after blending two liquids rises in viscosity within a short time, In some cases, the paint has a short usable time and is not easy to use. In addition, as disclosed in Japanese Patent Application Laid-Open No. 2002-53800 (Patent Document 1), when an amine-based catalyst is used, the effect of the urethanization catalyst is high, but the coating color changes to yellow. Problems may occur.

  The problem to be solved by the present invention is that the acrylic polyol-based resin and the polyisocyanate-based two-component curable coating have substantially sufficient pot life and the physical properties of the coated film are manifested. The aim is to provide a paint that has both the practicality of proceeding in an instant and finishing it in a short time, and excellent coating performance.

  As a result of intensive studies in view of the above problems, the inventors of the present invention react with a polyisocyanate instantly and a polyol containing an acrylic polyol synthesized with a specific composition, despite a short curing time. The present inventors have found that the coating film hardness capable of polishing the coating film is given, and further, the heat resistance that enables polishing finish is also exhibited. That is, the polymerizable monomer having 4 or more carbon atoms having a glass transition point (Tg) of 20 ° C. or higher of the polymer is 55 to 70% by mass, and 4-hydroxybutyl acrylate is 30 to 45% by mass. The acrylic polyol polymerized from 90% by mass or more of the essential specific mixture is rich in reactivity with isocyanate and exhibits excellent heat resistance even in a slight crosslinking reaction, and the acrylic polyol is 5% by mass or more. When the polyisocyanate, which is a curing agent, is blended with the polyol component that is contained, it has practically sufficient pot life, and the physical properties of the coated film progresses instantaneously, and the coating can be finished in a short time. The present invention was completed by confirming that the paint had both the properties and excellent coating performance.

  More specifically, the acrylic polyol (1) is a polymerizable monomer (a) 55 having an alkyl group having 4 or more carbon atoms and having a polymer glass transition point (Tg) of 20 ° C. or higher. To 70 mass% and 4-hydroxybutyl acrylate (b) 30 to 45 mass% is polymerized from 90 mass% or more. The polymerizable monomer (a) having an alkyl group having 4 or more carbon atoms and having a glass transition point (Tg) of the polymer of 20 ° C. or higher is a glass transition point of a monomer single polymer. (Tg) is a monomer having a temperature of 20 ° C. or higher, and has an alkyl group having 4 or more carbon atoms, excluding groups that contribute to polymerization. In addition, the alkyl group shown here contains a linear or branched thing, an alicyclic hydrocarbon group, and an aromatic hydrocarbon group. Specifically, a (meth) acrylic acid ester, styrene or a derivative thereof having a carbon number of butyl group or more and a glass transition point (Tg) of a monomer single polymer of 20 ° C. or more. Specifically, n-butyl methacrylate (Tg = 20 ° C.), iso-butyl methacrylate (Tg = 67 ° C.), tert-butyl methacrylate (Tg = 132 ° C.), cyclohexyl methacrylate (Tg = 83 ° C.) ), Isobornyl methacrylate (Tg = 180 ° C.), styrene (Tg = 100 ° C.) and the like, and tert-butyl methacrylate and isobornyl methacrylate are particularly preferable. The glass transition point (Tg) shown here can be determined by the DSC method which is obtained by measuring the calorific value with a differential scanning calorimeter.

  As a monomer constituting the acrylic polyol (1), except for 4-hydroxybutyl acrylate (b), use of a monomer having a polymer glass transition point of less than 20 ° C. is insufficient in heat resistance expression. In addition, the use of a monomer having 3 or less carbon atoms may cause problems such as an increase in the viscosity of the resulting resin liquid or cloudiness. Is preferably less than 10% by mass in the acrylic polyol (1), and has a polymer having an alkyl group having 4 or more carbon atoms and having a glass transition point (Tg) of 20 ° C. or higher. A monomer (a) of less than 55% by mass is also undesirable because it may cause problems such as an increase in the viscosity of the resulting resin. On the other hand, if it exceeds 70% by mass, the content of 4-hydroxybutyl acrylate (b) inevitably decreases, which is not desirable because the effect of rapid curability for the purpose of the present application decreases.

  Further, in order to obtain the acrylic polyol (1), 4-hydroxybutyl acrylate (b) rich in isocyanate reactivity is essential, and as a result, a low molecular weight polyisocyanate curing agent with low heat resistance is instantly used. The coating film having excellent heat resistance can be formed in a short time after coating. The amount of 4-hydroxybutyl acrylate (b) is suitably from 30 to 45% by mass, and when it is less than 30% by mass, the crosslinking density is low and sufficient coating film performance may not be exhibited, and it exceeds 45% by mass. In such a case, the number of hydroxyl groups becomes too high, so that the dissolving power of the resin in the solvent decreases, and problems such as increase in viscosity or cloudiness may occur.

 Next, the synthesis | combining method of acrylic polyol (1) is demonstrated. Monomers satisfying the conditions for obtaining the acrylic polyol (1) described above may be mixed and polymerized in a solvent in the presence of a radical initiator. The radical initiator used is preferably an organic peroxide, and specific examples include di-tert-butyl peroxide, tert-butyl peroxybenzoate, tert-butyl peroxyisopropyl carbonate, and the like. An initiator of about 1 to 5% by mass may be present at the time of polymerization with respect to the total weight.

  The solvent used for the synthesis may be an ester solvent, a ketone solvent, an aromatic solvent, a hydrocarbon solvent, etc., but it is sufficiently dissolved to dissolve the acrylic polyol (1) during and after polymerization. It is preferable to select a solvent composition having strength, and it is desirable to avoid aromatic solvents such as toluene and xylene from the viewpoint of recent environmental measures. The polymerization temperature may be determined in consideration of the decomposition temperature of the initiator used and the viscosity of the target paint.

  The acrylic polyol (1) thus obtained has a structure in which a 4-hydroxybutyl group is grafted from an acrylic main chain, and this acrylic polyol (1) has a characteristic of extremely high reactivity with polyisocyanate. doing. In other words, the hydroxyl group bonded to the end of the butylene chain is a primary hydroxyl group as compared with the hydroxyl group bonded to the ethylene chain or propylene chain having 2 or 3 carbon atoms such as 2-hydroxyethyl methacrylate and hydroxypropyl methacrylate. In addition, since it is a hydroxyl group with little steric hindrance and a high degree of freedom, the reactivity of the polyisocyanate (3) with the isocyanate group is high. In addition, since it is a resin with an extremely large amount of hydroxyl groups, it has the property of increasing the reaction rate with isocyanate within a short period of time after coating. It can be expressed. Further, the technical contents of the present invention will be explained. An acrylic resin having an extremely large amount of hydroxyl groups generally has a high viscosity or can no longer be dissolved in a solvent. In (1), since a polymerizable monomer having an alkyl group having 4 or more carbon atoms is copolymerized in a large amount, the solubility in a solvent is high, so that the viscosity is not remarkably increased.

  Next, other polyols that can be combined with the acrylic polyol (1) will be described.

  The other polyol component may be a resin having a lower reactivity than the acrylic polyol (1) as long as it is acrylic, and examples thereof include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3- Monomers having hydroxyl groups capable of reacting with isocyanates such as hydroxypropyl (meth) acrylate and glycerin mono (meth) acrylate, (meth) acrylic acid, methyl (meth) acrylate, ethyl (meth) acrylate, butyl Acrylic polyol copolymerized with (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, dicyclopentanyl (meth) acrylate, isobornyl (meth) acrylate, styrene, vinyltoluene, etc. All It is.

  As other polyols, use of polyester polyols is also possible. For example, polyols such as ethylene glycol, propylene glycol, neopentyl glycol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, trimethylolpropane, pentaerythritol, succinic acid, adipic acid, cyclohexanedicarboxylic acid, sebacic acid And polyester-based polyols obtained by dehydration condensation of polycarboxylic acids such as azelaic acid, phthalic acid, isophthalic acid and terephthalic acid.

  The acrylic polyol (1) is mixed with the other polyols described above to form the polyol component (2) as the main agent. The proportion of the acrylic polyol (1) is preferably such that at least the acrylic polyol (1) is 5% by mass or more in the main component of the polyol (2). The rapid curing property is not remarkable. In applications where a long pot life is not required, by setting the acrylic polyol (1) to 95% by mass or more, remarkable rapid curability can be exhibited and the object of the present application can be satisfied. In applications where both long pot life and fast curability are required, it is possible to satisfy both pot life and fast curability by containing 5 to 50% by weight of acrylic polyol (1). it can.

  Next, polyisocyanate (3) which is a curing agent will be described. The isocyanate to be used is not particularly limited as long as it has two or more isocyanate groups in one molecule, and any of aromatic polyisocyanates and aliphatic polyisocyanates can be used. However, from the viewpoint of weather resistance, an aliphatic isocyanate is desirable, and more specifically, for example, hexamethylene diisocyanate, isophorone diisocyanate, norbornene diisocyanate, hydrogenated MDI, and the like, trimethylolpropane adduct and burette body. , Allophanate, and isocyanurate (trimer). Among them, it is isocyanurate (trimer) that makes the manifestation of heat resistance remarkable. In order to express aptitude, isocyanurate (trimer) is preferred.

  Furthermore, with regard to the type of isocyanate, it is preferable to use a mixture of hexamethylene diisocyanate having high reactivity with hydroxyl groups and isophorone diisocyanate having low reactivity with hydroxyl groups. Not only can the usage time be delayed, but also exhibits the physical properties that allow polishing and polishing operations to be performed within a short period of time after coating, and the advantage that the possible time span for polishing and polishing operations can be maintained long. Explaining a specific blending ratio, a blend of hexamethylene diisocyanate trimer: isophorone diisocyanate trimer at 95: 5 to 60:40 parts by mass is preferable. When the hexamethylene diisocyanate exceeds 95% by mass, the effect of delaying the pot life after blending is hardly obtained, and when it is less than 60% by mass, the reaction rate is low and the polishing suitability tends to be poor.

  Further, by modifying the trimer of hexamethylene diisocyanate in polyisocyanate (3) with a specific monoalcohol, it is possible to further promote the development of heat resistance for the purpose of the present application and lengthen the pot life. . Specifically, with respect to 100 parts by mass of the hexamethylene diisocyanate trimer constituting polyisocyanate (3), 0.5 to 10 parts by mass of a monoalcohol having 6 to 12 carbon atoms can be converted into a urethane bond. The modified one is good.

  Specific examples of the monoalcohol having 6 to 12 carbon atoms include hexanol, cyclohexanol, 2-ethylhexanol, 4-methylcyclohexanol, ethylene glycol monohexyl ether, borneol, and isoborneol. The modified polyisocyanate using cyclohexanol, borneol, or isoborneol improves the compatibility of mist during spray coating, and further increases the speed of heat resistance and increases the pot life.

  In the method of modifying the monoalcohol to the hexamethylene diisocyanate trimer, 0.5 to 10 parts by mass of monoalcohol is added to 100 parts by mass of the hexamethylene diisocyanate trimer, and the temperature is about 40 ° C to 60 ° C. It is sufficient to heat and stir until the alcohol is consumed. When the monoalcohol is solid, it is preferable to add a solution previously dissolved in a solvent.

  Next, the blending ratio of the polyol component (2) serving as the main agent and the polyisocyanate (3) serving as the curing agent will be described. More preferably, the blend of the main component polyol component (2) and the curing agent polyisocyanate (3) is such that the number of isocyanate groups is about 80 to 140 with respect to 100 hydroxyl groups of the polyol component (2). What is necessary is just to mix | blend with respect to 100 so that the number of isocyanate groups may be in the range of about 90 to 120. If the number of isocyanate groups is 80 or less, a coating film having a low crosslinking density and excellent heat resistance may not be provided. If it exceeds 140, curing may be poor or carbon dioxide gas is generated from the coating during the curing process. May cause malfunctions.

  In addition, an appropriate amount of a urethanization reaction catalyst can be added to the polyol (2) serving as the main agent or the polyisocyanate (3) serving as the curing agent, if necessary, in order to adjust the curing rate. As the urethanization catalyst, known tin-based and amine-based catalysts can be used. However, tin-based catalysts are preferable because amine-based catalysts may change color or deteriorate weather resistance. Specific examples include dibutyltin dilaurate, dibutyltin dimaleate, dioctyltin dilaurate and the like, and an appropriate amount may be added in consideration of the balance between pot life and curing speed.

  The fast-curing resin composition of the present invention can be used as a clear paint, and can also be used as a paint to which a coloring pigment, filler, etc. are added, and includes a leveling agent, an ultraviolet absorber, and a hindered amine. Various additives such as antifoaming agents can be added, and color pigments such as titanium dioxide, ferric oxide, carbon black, phthalocyanine blue, and extender pigments such as barium sulfate, calcium carbonate, talc, etc. Can do.

The two-component blended acrylic urethane resin obtained by the present invention enables paper sharpening and compound finishing in a short time after painting, and improved fast curability and further delay in pot life. It is a thing.

  EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. In the description including the following table, the unit of the blending amount is in principle parts by mass.

Synthesis of acrylic polyol (1) In a nitrogen atmosphere, 250 g of xylene was charged into a 2 L flask and refluxed. While stirring, the composition (500 g) of Table 1 and Table 2 and the polymerization initiator (20 g) were added dropwise over 6 hours. Further, the reaction was continued at the reflux temperature for 4 hours. After cooling to room temperature, 230 g of butyl acetate was added to complete the reaction. Examples (1) -1 to (1) -8 were used as examples, and (1) -9 was used as a comparative example. From (1) -12, a resin solution having a solid content of 50% by mass was obtained. The polymerization initiator is an aliphatic hydrocarbon solvent solution containing 75% tert-butyl peroxyisopropyl carbonate. Tables 1 and 2 show that the polymerizable monomer (a) having an alkyl group having 4 or more carbon atoms and having a glass transition point (Tg) of the polymer of 20 ° C. or higher and 4-hydroxybutyl The content of (a) contained in the total of acrylate (b) is defined as “(a) content (%)”, and the content of 4-hydroxybutyl acrylate (b) is represented by “(b ) Content (%) ", the respective calculated values are described. Furthermore, the calculated values are described with the contents of (a) and (b) included in (1) as “essential component amount (%)”.

The abbreviations and raw materials described below are as follows.
t-BMA: tert-butyl methacrylate
i-BMA: iso-butyl methacrylate
MMA: Methyl methacrylate
2-EHMA: 2-ethylhexyl methacrylate IBX: isobornyl methacrylate STY: styrene MAA: methacrylic acid
2-HEMA: 2-hydroxyethyl methacrylate HPMA: 2-hydroxypropyl methacrylate and 3-hydroxypropyl methacrylate
Rate mixture
4-HBA: 4-hydroxybutyl acrylate HDI: hexamethylene diisocyanate IPDI: isophorone diisocyanate

Synthesis of other polyol (4) constituting polyol (2) as the main agent In a nitrogen atmosphere, 250 g of xylene was charged into a 2 L flask and refluxed. While stirring, the composition shown in Table 3 (500 g) and the polymerization initiator (25 g) were added dropwise over 6 hours. Further, the reaction was continued for 4 hours at the reflux temperature, and after cooling to room temperature, 225 g of butyl acetate was added to complete the reaction, and other polyols (4) -1 and (4)- 2, a resin solution having a solid content of 50% by mass was obtained. The polymerization initiator is an aliphatic hydrocarbon solvent solution containing 75% tert-butyl peroxyisopropyl carbonate.

Preparation of polyol (2) as main agent Acrylic polyols (1) -1 to (1) -8 and (1) -9 to (1) -12 obtained previously, other polyols (4) -1 and (4) -2 was adjusted according to the formulation shown in Tables 4 and 5, and main component polyols (2) -1 to (2) -9 and (2) -10 to (2) -15 were obtained. Further, as comparative examples, main compositions of (2) -16 to (2) -19 as comparative examples and other polyols (4) -1 and (4) -2 as reference examples in the composition of Table 6. The coating materials obtained were also prepared as (2) -20 and (2) -21.

Adjustment of Curing Agent (3) In a nitrogen atmosphere, 100 g of HDI trimer (Duranate TPA-100 manufactured by Asahi Kasei Chemicals Co., Ltd.) was charged into a 500 ml flask, and butyl acetate (100 g) was added and stirred to be uniform. Separately, a monoalcohol (3 g) such as 2-ethylhexanol dissolved in butyl acetate (3 g) was prepared, added to a flask, and reacted at 60 ° C. for 6 hours, each having a solid content of 50% by mass. The polyisocyanate resin liquid was obtained. The obtained polyisocyanates were designated as (3) -1 to (3) -5, respectively. Moreover, the quantity of isobornyl alcohol was changed into the above, and the obtained polyisocyanate was set to (3) -6 and (3) -7. In Table 7, only the used amounts of HDI trimer and alcohol were used.

  Furthermore, the hardening | curing agent which mix | blended the HDI trimer and IPDI trimer (Degussa Vestanat T-1890 / 100) was adjusted as a hardening | curing agent. The adjusting method produced 50 mass% solution of butyl acetate, respectively, and mix | blended with the composition shown in Table 8, and obtained (3) -8 to (3) -10 of 50% of solid content. Further, the curing agents (3) -3 and (3) -4 obtained in Table 7 were blended with the IPDI trimer to obtain (3) -11 and (3) -12, respectively.

  Moreover, as a comparative example of the curing agent, curing agents were prepared with the compositions shown in Table 9 and Table 10, and (3) -13 to (3) -18 were obtained, respectively.

Evaluation of fast curability Dibutyltin dilaurate (0.05%) was added to the obtained main agents (2) -1 to (2) -21, and HDI trimer (3) -1 as a curing agent was added thereto. Blended. The mixing ratio was such that the amount of hydroxyl groups in the main agent and the amount of isocyanate groups in the curing agent were equivalent. However, polyols (2) -17 and (2) -18 obtained from (1) -10 and (1) -11 synthesized as comparative examples have poor compatibility and are uniform when mixed with a curing agent. Evaluation was not performed because the paint was not suitable. The other blended paints 1 to 21 were evaluated as 1 by spraying Protouch White manufactured by Rock Paint Co., Ltd., and coating each blended paint to a film thickness of 50 to 55 μm. C. x 10 minutes. The coating film is returned to room temperature, the surface is polished with 3M water-repellent paper sheet (soft type) # 1200, and the polishing part is made of 3M's wool buff "Cut 1" and the company's sponge buff "Hard 2L". Polished with a compound and evaluated. As the evaluation 2, the drying time was 60 ° C. × 20 minutes, and the paper polishing property and the compound polishing property were similarly evaluated. The evaluation criteria is a five-level evaluation: “1” when the paint film is abundant and cannot be polished at the time of paper polishing, “2” when polishing is completed but the paint film is touched at the time of compound finishing, compound finish However, when it was observed the next day, the paper wound was returned as “3”, and the paper finished without any damage as “5”. In addition, the pot life was measured for each of the blended paints. This recorded the time from compounding to the point of marked increase in viscosity. The results are shown in Table 11.

  Next, in order to investigate the performance of the curing agent, the main agent was unified to (2) -1, and the curing agents were blended from (3) -2 to (3) -18. The mixing ratio was such that the amount of hydroxyl groups in the main agent and the amount of isocyanate groups in the curing agent were equivalent. From the obtained blended coating material 22, the coating material 38 was evaluated by the above-described Evaluation 1 and Evaluation 2, and the pot life was measured in the same manner. The results are shown in Table 12.

  As described above, it has been confirmed that the two-component blended acrylic urethane resin according to each of the above-described embodiments provides a paint that can be sharpened and compounded even in a short time after coating.

Claims (6)

The main component is a polyol component (2) containing 5% by mass or more of an acrylic polyol (1) polymerized from a monomer containing 90% by mass or more of an essential specific mixture, and polyisocyanate (3) is blended as a curing agent. Become
The essential specific mixture is composed of a polymerizable monomer (a) having an alkyl group having 4 or more carbon atoms and having a glass transition point (Tg) of the polymer of 20 ° C. or higher, and 4-hydroxybutyl acrylate. A mixture with (b),
In the essential specific mixture, the polymerizable monomer (a) is 70 mass% from 55 state, and are not 4-Hiro de carboxybutyl acrylate (b) is 30 to 45 wt% blend,
The polyisocyanate (3) is composed of a trimer of hexamethylene diisocyanate and a trimer of isophorone diisocyanate, and the ratio of the trimer of hexamethylene diisocyanate and the trimer of isophorone diisocyanate is 95 parts by mass: A fast-curing resin composition characterized by being 5-60: 40. The hexamethylene diisocyanate trimer is modified with a urethane bond,
Modification of the above claims with respect to 100 parts by weight trimer of hexamethylene diisocyanate prior denaturation, characterized in that made by adding 10 parts by mass monoalcohol 0.5 having 6 to 12 carbon atoms Item 2. A fast-curing resin composition according to item 1 .   The main component is a polyol component (2) containing 5% by mass or more of an acrylic polyol (1) polymerized from a monomer containing 90% by mass or more of an essential specific mixture, and polyisocyanate (3) is blended as a curing agent. Become
The essential specific mixture is composed of a polymerizable monomer (a) having an alkyl group having 4 or more carbon atoms and having a glass transition point (Tg) of the polymer of 20 ° C. or higher, and 4-hydroxybutyl acrylate. A mixture with (b),
In the essential specific mixture, 55 to 70% by mass of the polymerizable monomer (a) and 30 to 45% by mass of 4-hydroxybutyl acrylate (b) are blended,
The polyisocyanate (3) contains a trimer of hexamethylene diisocyanate,
The trimer of hexamethylene diisocyanate is modified with a urethane bond,
The above-mentioned modification was performed by adding 0.5 to 10 parts by mass of a monoalcohol having 6 to 12 carbon atoms with respect to 100 parts by mass of the hexamethylene diisocyanate trimer before modification. A curable resin composition. The polymerizable monomer (a) having an alkyl group having 4 or more carbon atoms and having a glass transition point (Tg) of 20 ° C. or higher contains at least one of tert-butyl methacrylate and isobornyl methacrylate. The fast-curing resin composition according to any one of claims 1 to 3 . The fast-curing resin composition according to any one of claims 1 to 4, wherein the main component is a polyol component (2) containing 95% by mass or more of the acrylic polyol (1). The fast-curing resin composition according to any one of claims 1 to 4, wherein the main component is a polyol component (2) containing 5 to 50% by mass of the acrylic polyol (1).