Unsaturated polyester resin composition and method for producing the same

Abstract

The present invention provides an unsaturated polyester resin composition comprising a (meth)acrylate compound and a polyester formed from at least the following reagents: a) a reagent containing itaconic acid and / or itaconic anhydride; b) a reagent containing maleic acid, maleic anhydride, and / or fumaric acid; c) a reagent containing dicyclopentadiene (DCPD); and d) a reagent comprising at least one di- or polyfunctional alcohol, preferably at least one diol; The present invention relates to an unsaturated polyester resin composition in which the total weight of the reagent a) (i.e., the total weight of itaconic acid and / or itaconic anhydride) is 10% by weight or more, preferably 20% by weight or more, of the total weight of the dibasic acids and anhydrides used in the unsaturated polyester resin composition. The present invention further relates to the use of the unsaturated polyester resin for structural parts and gel coats. The present invention also provides a manufacturing method for preparing the unsaturated polyester resin composition.

Description

Technical Field

[0001] The present invention relates to the field of unsaturated polyester resin compositions and to methods for producing such compositions. In particular, the present invention aims to provide a polyester resin composition with low odor and low emissions.

Background Art

[0002] Unsaturated polyester resin compositions are used, inter alia, for manufacturing composite parts and products, especially within unconfined (open) molds. In composite parts and products, it is common to add reinforcing fibers to the resin composition. For efficient production and satisfactory performance of the final product, the resin composition needs to meet many requirements.

[0003] The unsaturated polyester resin composition needs to flow well, for example, to fill the spaces between the reinforcing fibers, but if it becomes too dilute, the composition will flow out again before curing, so it is necessary to balance the viscosity of the unsaturated polyester resin composition so that it does not become too low.

[0004] The curing time of the unsaturated polyester resin composition needs to be adjusted so as to ensure sufficient processing time to bond the liquid unsaturated polyester resin composition and the reinforcing fibers in the mold, but once curing has started, the curing time must not be so long that the product hardness cannot reach a level at which demolding is possible. A common method for evaluating whether the resin curing is sufficient for demolding is to measure the hardness according to ASTM - 648 using a Barcol 934.1 test apparatus. The value on the hardness scale is preferably 10 or more, more preferably 20 or more.

[0005] In the finished product, the cured resin needs to be resistant to the mechanical loads and temperatures expected during the product life. Therefore, the heat distortion temperature (HDT) of the cured resin must be sufficiently high.

[0006] Unsaturated polyester resin compositions containing styrene as a reactive diluent can meet some of these requirements. However, they release a significant amount of VOCs during processing. Furthermore, styrene is classified as carcinogenic, mutagenic, or reprotoxic (CMR). This means that appropriate ventilation (and optional treatment of the ventilation air) is necessary to avoid exposing workers to high concentrations of styrene in the environment. For this reason, unsaturated polyester resin compositions preferably use a non-volatile reactive diluent that has a low odor and is preferably not CMR. However, such existing unsaturated polyester resin compositions generally have insufficient surface curing or inferior strength or heat resistance.

[0007] Unsaturated polyester resin compositions are cured by radical polymerization. Radical polymerization is generally strongly inhibited by oxygen. For unsaturated polyester resin compositions applied in an open mold, it is known that the air side of the resin is difficult to cure. In the case of resins using a volatile reactive diluent such as styrene, when physically dried, a polyester-rich layer that is almost solid remains on the surface. This (almost) solid polyester-rich layer forms a barrier layer against oxygen, thereby enabling the resin just below the surface to be properly cured and forming a surface that feels dry to the touch (tack-free). When using a non-volatile diluent, solidification occurs only by radical polymerization, and curing is strongly inhibited by oxygen on the surface exposed to air. On the surface of a resin using a non-volatile reactive diluent, even one day after the start of curing, it is often still liquid or remains sticky. In other cases, the surface may be soft due to insufficient surface curing.

[0008] US2004 / 0220340 describes a styrene-free resin composition produced by combining an unsaturated polyester and a urethane (meth)acrylate. In the claims of this application, it is stated that in order to achieve appropriate performance, it is necessary to mix an unsaturated polyester resin with a hydroxyl (meth)acrylate and a urethane (meth)acrylate. These resins are prone to water absorption due to their high hydroxyl group concentration, which, as an inherent property of the material, will reduce the hydrolysis resistance. Furthermore, the production of these resins is relatively complex. The claimed resin composition requires synthesizing two different resins according to different procedures and combining them. If both resins are produced in the same reactor, a washing step is required in the middle. Alternatively, if separate dedicated reactors are used for different resins, separate mixing tanks are required for the two types of resins. Either method becomes much more complex than the production of standard unsaturated polyester resins due to the necessary equipment, process planning, and logistics. The more complex it becomes, the higher the production cost and the greater the chance of errors during production. Therefore, a resin composition that can be produced in one reactor and a single batch is highly preferred.

[0009] US2015 / 0018479 describes the use of diallyltrimethylolpropane methacrylate as a diluent to improve surface curing. This solution provides reasonable curing but has another drawback. In open applications, curing is usually initiated by peroxides. Peroxides need to be activated by accelerators. The most commonly used accelerator is cobalt octoate. Cobalt and other oxidation-type driers catalyze the oxidation of allyl ether groups from diallyltrimethylolpropane methacrylate, resulting in the formation of acrolein. Since acrolein is volatile, highly toxic, and carcinogenic, this side reaction occurring is highly undesirable. This side reaction is generally known to occur when using cobalt and oxidation-type driers. Thus, it is preferable to avoid using allyl ether groups in combination with cobalt or other transition metals in open applications.

[0010] UV curable resins are typically produced using low volatility acrylate or methacrylate diluents. In such resins, insufficient surface curing is a well-known drawback. A list of different additives that can improve surface curing is described in Progress in Organic Coatings 77(2014)pl789-1798. All of the additives described have drawbacks such as unsaturated polyester resins, toxicity, unusual odors, yellowing, and difficulty in obtaining. None of these additives are suitable for open-type applications of unsaturated polyesters where storage stability and safe use are essential.

[0011] Another method of improving surface curing is to post-cure the unsaturated polyester resin composition at a high temperature, for example 60 to 80 °C. This post-curing is energy-intensive, increases the cycle time, and requires special equipment. These drawbacks become most prominent when the product is enlarged.

[0012] Preferably, the cured resin should be able to withstand the expected loads and temperatures in the product. In various applications, the minimum values can vary widely. However, in the case of applications to structures, typically the following minimum requirements are set. The HDT of the resin is preferably 55 °C or higher, more preferably 60 °C or higher. The elongation at break (breaking elongation) is preferably 1.5% or higher, more preferably 2.0% or higher, most preferably 2.5% or higher. The modulus of the resin is 2.0 GPa or higher, preferably 2.5 GPa or higher, more preferably 3.0 GPa or higher, most preferably 3.5 GPa or higher. The tensile strength is preferably 30 MPa or higher, preferably 40 MPa or higher, more preferably 50 MPa or higher, most preferably 60 MPa or higher. SUMMARY OF THE INVENTION

[0013] The present invention provides a resin composition that addresses one or more of the above problems. Preferred embodiments of the present invention also solve one or more of the above problems.

[0014] An object of the present invention is to provide a curable resin composition that can be improved with respect to VOC emission while maintaining sufficient performance with respect to the curing and mechanical properties of the cured product.

[0015] Another object of the present invention is to provide an unsaturated polyester resin composition that emits little VOC or harmful air pollutants (HAP), contains no styrene or has a low styrene content, especially when these resin compositions are used in open applications.

[0016] Another object of the present invention is to provide an unsaturated polyester resin composition that cures very fast. Preferably, the hardness of the product according to ASTM-648 using a Barcol 934.1 test apparatus is more than 10 on the scale of the apparatus, more preferably 20 or more. When sufficient hardness is reached, the manufactured parts can be removed from the mold. The required hardness is preferably achieved after 24 hours, more preferably after 16 hours, still more preferably after 4 hours, and most preferably after 2 hours, depending on the desired demolding time.

[0017] Another object of the present invention is to provide an unsaturated polyester resin composition that can provide a tack-free surface within 24 hours from the start of curing, even when an open mold is used, preferably on both the surface in contact with the mold and the surface in contact with the atmosphere.

[0018] Another object of the present invention is to provide an unsaturated polyester resin composition having a sufficiently high HDT, preferably HDT of 55°C or higher, more preferably 60°C or higher.

[0019] Another object of the present invention is to provide an unsaturated polyester resin composition for structural resins and gel coat resins.

[0020] Another object of the present invention is to provide an unsaturated polyester resin composition that is not classified as CMR.

[0021] These and other objects, features, and advantages of the present invention will become apparent from the following detailed description.

[0022] One aspect of the present invention provides an unsaturated polyester resin composition comprising the following. (Meth)acrylate compound and itaconate compound as an optional component, and a polyester formed from at least the following reagents, a) a reagent containing itaconic acid and / or itaconic anhydride; b) a reagent containing maleic acid, maleic anhydride, and / or fumaric acid; c) a reagent containing dicyclopentadiene (DCPD); and d) a reagent containing at least one difunctional or polyfunctional alcohol; The total weight of reagent a) is 10% by weight or more, preferably 20% by weight or more, of the total weight of dicarboxylic acids and anhydrides used in the unsaturated polyester resin composition.

[0023] In some embodiments, a reaction mixture is formed from reagent b), reagent c), and optionally reagent a) before the polyester is formed. In embodiments where the reaction mixture is formed from reagent b) and reagent c), the polyester is formed from the resulting reaction mixture, reagent a), and reagent d). In embodiments where the reaction mixture is formed from reagent b), reagent c), and reagent a), the polyester is formed from the resulting reaction mixture and reagent d).

[0024] In some embodiments, the weight of the volatile organic compound (VOC) is less than 10% by weight, preferably less than 5% by weight, more preferably less than 2% by weight, and even more preferably less than 1% by weight of the total weight of the unsaturated polyester resin composition. In some embodiments, the total weight of styrene, α-methylstyrene, vinyltoluene and / or methyl methacrylate is less than 10% by weight of the total weight of the unsaturated polyester resin composition, preferably less than 5% by weight, more preferably less than 2% by weight, and even more preferably less than 1% by weight. Preferably, the vapor pressure of the diluent is less than 100 Pa (20 °C), more preferably less than 10 Pa (20 °C).

[0025] In some embodiments, the weight of the (meth)acrylate compound is at least 5 to 95% by weight, preferably 10 to 70% by weight, more preferably 20 to 60% by weight, most preferably 30 to 50% by weight, for example 40% by weight of the total weight of the unsaturated polyester resin composition. Methacrylate is more preferred than acrylate in view of the advantageous differences in skin sensitization.

[0026] In some embodiments, the (meth)acrylate compound in the unsaturated polyester resin composition functions as a diluent, preferably a reactive diluent.

[0027] In some embodiments, the unsaturated polyester resin composition contains an itaconate compound, preferably a dialkyl itaconate, more preferably dimethyl itaconate (DMI).

[0028] In some embodiments, the unsaturated polyester resin composition contains dimethyl itaconate or other itaconate monomers, preferably as a diluent, more preferably as a reactive diluent. Itaconate monomers can be used alone or in combination with methacrylate and / or acrylate diluents.

[0029] In some embodiments, the total weight of the itaconate compound and the (meth)acrylate compound is at least 5 to 95% by weight, preferably 10 to 70% by weight, more preferably 20 to 60% by weight, most preferably 30 to 50% by weight, for example 40% by weight, of the total weight of the unsaturated polyester resin composition. The ratio of the itaconate to the (meth)acrylate compound is not particularly limited, but it is preferable that at least 1 / 4 of the weight of the diluent is the (meth)acrylate compound, at least 1 / 3 of the weight of the diluent is the (meth)acrylate compound, and most preferably at least 1 / 2 of the weight of the diluent is the (meth)acrylate compound.

[0030] In some embodiments, the added weight of DCPD is at least 10% by weight of the total weight of the polyester.

[0031] In some embodiments, the unsaturated polyester resin composition contains a transition metal salt or a transition metal complex. In some embodiments, the unsaturated polyester resin composition contains a cobalt salt or a cobalt polymer.

[0032] In some embodiments, the unsaturated polyester resin composition may contain a photoinitiator. In some embodiments, the unsaturated polyester resin composition may contain an inorganic filler.

[0033] A further aspect of the present invention provides the use of the unsaturated polyester resin composition described herein, or an embodiment thereof, preferably as a structural material for structural parts formed in an open mold. A further aspect of the present invention provides the use of the resin described herein or an embodiment thereof as a composition for gel coat or a composition for coating, preferably in an open mold.

[0034] In yet another aspect, the present invention provides a method for producing an unsaturated polyester resin composition, preferably an unsaturated polyester resin composition according to an embodiment of the present invention, the method comprising the following steps. A step of forming a polyester from at least the following reagents: a) A reagent containing itaconic acid and / or itaconic anhydride; b) A reagent containing maleic acid, maleic anhydride, and / or fumaric acid; c) A reagent containing dicyclopentadiene (DCPD); and d) A reagent containing at least one bifunctional or polyfunctional alcohol; A step of mixing the obtained polyester with a (meth)acrylate compound and optionally an itaconate compound to obtain an unsaturated polyester resin composition, The total weight of the reagent a) is 10% by weight or more, preferably 20% by weight or more, of the total weight of the dicarboxylic acids and anhydrides used in the unsaturated polyester resin composition.

[0035] In some embodiments, the method includes forming a reaction mixture from reagent b), reagent c), and optionally reagent a) before forming the polyester. In embodiments where the reaction mixture is formed from reagent b) and reagent c), the polyester is formed from the obtained reaction mixture and reagent a) and reagent d). In embodiments where the reaction mixture is formed from reagent b), reagent c), and reagent a), the polyester is formed from the obtained reaction mixture and reagent d).

[0036] Preferred embodiments of the resins described herein are also preferred embodiments for use and methods, and vice versa.

Mode for Carrying Out the Invention

[0037] As used hereinafter, the singular forms "a", "an", and "the" include both the singular and the plural unless the context clearly dictates otherwise.

[0038] The term "comprise or comprises" is, as used hereinafter, synonymous with "including or include" or "contain", and "contain" is inclusive or open and does not exclude the addition of parts, elements or method steps not recited. When referring herein to a product or process "comprising" a particular feature, part or step, it means that other features, parts or steps may be present, but it is also possible to refer to an embodiment comprising only the recited feature, part or step.

[0039] Examples of numbers by numerical ranges include all values and sub-ranges within these ranges, as well as the recited endpoints. [[ID=;6]]

[0040] The term "about", when used in reference to a measurable value such as a parameter, amount, period, etc., is intended to include variations of + / - 10% or less, preferably + / - 5% or less, more preferably + / - 1% or less from a particular value, insofar as such modifications are applicable to the invention disclosed herein. It should be understood that the term "about" also means the value disclosed as itself.

[0041] All references cited herein are considered to be incorporated by reference in their entirety.

[0042] Unless otherwise limited, all terms disclosed in the present invention, including technical and scientific terms, have the meanings that those skilled in the art would ordinarily ascribe to them. For further guidance, definitions are included to further explain the terms used in the description of the present invention.

[0043] The present invention broadly provides an unsaturated polyester resin composition improved with respect to surface curing properties. The resin composition of the present invention can exhibit efficient curing in a thin laminate, even in an air atmosphere at ambient temperature. Further, the present invention broadly provides an unsaturated polyester resin having a good balance of tensile strength, elongation at break, HDT, surface hardness, processability, and ease of manufacture.

[0044] Furthermore, the present invention provides an unsaturated polyester resin composition that does not contain styrene or has a low styrene content so as to reduce the emission of VOC or harmful air pollutants (HAP) when these resin compositions are used in open air, particularly for applications in an open type.

[0045] One aspect of the present invention provides an unsaturated polyester resin composition comprising the following. (Meth)acrylate compound; and a polyester formed from at least the following reagents a) a reagent containing itaconic acid and / or itaconic anhydride; b) a reagent containing maleic acid, maleic anhydride, and / or fumaric acid; c) a reagent containing dicyclopentadiene (DCPD); and d) a reagent containing at least one bifunctional or polyfunctional alcohol, preferably at least one diol. Here, the total weight of reagent a) (i.e., the total weight of itaconic acid and / or itaconic anhydride) is 10% by weight or more, preferably 20% by weight or more of the total weight of dicarboxylic acids and anhydrides used in the unsaturated polyester resin composition.

[0046] The presence of DCPD residues in the unsaturated polyester is beneficial for surface curing. DCPD helps the surface curing of a resin composition having a (meth)acrylate compound as a reactive diluent, but by itself, it is not effective enough to sufficiently compensate for the much inferior curing initiation of the resin composition when using a non-volatile reactive diluent compared to a resin composition containing a large amount of styrene. After 24 hours, the resin surface can be felt to be dry to the touch, but the top layer is not yet cured and remains soft. Surprisingly, it has been found that the incorporation of itaconic acid residues and maleic or fumaric acid residues in the DCPD-polyester resin exerts a synergistic effect of significantly improving the hardness of the resin surface.

[0047] Furthermore, the polyester has been found to be beneficial for the viscosity of the uncured resin composition, improves the mechanical properties and heat distortion temperature of the cured resin product after curing, and further enables reduction of the water absorption rate. Although the above-described properties also depend on the selection of the reactive diluent, the polyester used in the present invention has been found to be more favorably balanced with the above-described properties as compared with the conventional polyester backbone in the same reactive diluent.

[0048] The term "total weight of itaconic acid and itaconic anhydride" means the sum of the weights of all itaconic acid and itaconic anhydride when used to form the unsaturated polyester resin composition.

[0049] In some embodiments, the reaction mixture is formed from reagent b), reagent c) and any reagent a) before the polyester is formed.

[0050] In one embodiment, the polyester is formed from four reagents a), b), c) and d), but it should be noted that the reaction mixture may also be formed from only reagents b) and c). When the reaction mixture is formed from two reagents, reagent b) and reagent c), and three reagents of reagent a), reagent d) is added to the reaction mixture to form the polyester.

[0051] In some embodiments, the reaction mixture is formed from the following. Reagent b) and reagent c); or Reagent a), reagent b) and reagent c)

[0052] In some embodiments, the reaction mixture is formed in the presence of water, particularly when the reagent contains an anhydride.

[0053] In some embodiments, the anhydride present in reagent a) and / or reagent b) is hydrolyzed before forming the reaction mixture. Preferably, water is added to the reagent containing the anhydride and the reagent is heated.

[0054] In some embodiments, during the formation of the polyester, it is preferred that water is removed by distillation.

[0055] The following resin combinations containing (meth)acrylate and / or itaconate-containing compounds as diluents are: (i) an unsaturated polyester resin containing itaconic acid residues, maleic residues and DCPD residues; (ii) an unsaturated polyester resin containing itaconic acid residues, fumaric acid residues and DCPD residues.

[0056] The production of DCPD-maleic acid polyester is known to those skilled in the art. However, the method of the present invention may differ from standard practice in the form in which itaconic acid is added in the DCPD addition step or the polycondensation step. In some embodiments, the added weight of DCPD is 10% by weight or more of the total weight of the polyester.

[0057] In some embodiments, the preferred method involves heating a mixture of maleic anhydride, water, and optionally itaconic acid to about 130 - 140 °C, during which maleic anhydride reacts with water to form maleic acid. Preferably, a clear solution is formed, but it may also be a slurry that flows well with solid itaconic acid. When DCPD is added to this mixture, an exothermic reaction begins. The addition rate of DCPD is preferably adjusted to a temperature not exceeding 150 °C, more preferably not exceeding 140 °C, to avoid a dangerous decomposition reaction. In another method, DCPD is part of the starting mixture, and water or maleic anhydride is added while adjusting the rate. After adding all the acid, water, and DCPD, the mixture needs to be reacted at 130 - 150 °C for 1 hour or more to achieve a sufficient conversion rate.

[0058] Preferably, the initial mixture to which DCPD is added contains maleic acid, water, and itaconic acid.

[0059] More preferably, the ratio of maleic acid to itaconic acid is 1:4 to 2:1, and most preferably, the ratio is 1:2 to 1.5:1.

[0060] Alternatively, first, DCPD-maleic acid is produced by a standard procedure, and then itaconic acid is added such that the ratio of maleic acid to itaconic acid is from 1:4 to 2:1. The most preferred ratio is from 1:2 to 1.5:1.

[0061] In some embodiments, the next step is a polycondensation step to which diols and / or glycols, and optionally additional itaconic acid or other dibasic acids or anhydrides are added. Various methods are known in the art as polycondensation processes.

[0062] In some embodiments, all reactants are heated to 150 - 250 °C, preferably by distillation, to remove water and form a polymer.

[0063] In some embodiments, the method includes flushing the mixture with an inert gas such as nitrogen during polycondensation and / or reducing the pressure in the reactor. This allows water to be removed more efficiently.

[0064] In some embodiments, toluene is added to facilitate the removal of water by azeotropic distillation. This method can be carried out at a lower temperature such as 100 - 120 °C, which promotes polycondensation with thermally labile components. Other inert solvents that form an azeotropic mixture with water can also be used.

[0065] In some embodiments, the total amount of DCPD and hydroxyl groups must be approximately equal to the amount of acid groups on a molar basis. Approximately equal means that the amount of DCPD + hydroxyl groups is 80 - 120%, preferably 110 - 90%, most preferably 110 - 100% of the amount of acid groups.

[0066] In some embodiments, for smooth processing, the viscosity of the unsaturated polyester resin is preferably 100 to 2000 mPa·s, more preferably 150 to 1000 mPa·s, and most preferably 200 to 600 mPa·s at 23°C. In one aspect, a viscous additive is used to impart thixotropy.

[0067] In some embodiments, to initiate curing, methods known in the art can be employed. For example, peroxide-accelerator systems, UV curing, thermal initiators, and / or electron beams can be mentioned. More specific examples include combinations of MEKP peroxide with cobalt and / or other accelerators and BPO-amine initiators.

[0068] In some embodiments, the polycondensation is promoted by the addition of a catalyst.

[0069] In some embodiments, the polycondensation is stopped before reaching full conversion. A common method for determining the conversion rate is by measuring the acid value according to ISO2114-2000. However, in some embodiments, the acid value of the unsaturated polyester resin is preferably in the range of 10 to 100 mgKOH / g resin, more preferably 15 to 60 mgKOH / g resin, and most preferably 20 to 50 mgKOH / g resin.

[0070] In some embodiments, in addition to the above dibasic acids, other dibasic acids can be included in the resin composition. Typical examples of suitable dibasic acids and anhydrides include fumaric acid, citraconic acid, citraconic anhydride, mesaconic acid, oxalic acid, succinic acid, adipic acid, sebacic acid, tetrahydrophthalic acid, phthalic acid, phthalic anhydride, terephthalic acid, and isophthalic acid. Dibasic acids not explicitly mentioned can be used as well, and the compositions of the present invention are not limited to the listed dibasic acids which are only guided to those skilled in the art. Furthermore, monobasic acids, tribasic acids, and more polybasic acids may also be included in the composition. Typical examples of suitable monobasic acids include (meth)acrylic acid, lactic acid, benzoic acid, and the like.

[0071] In some embodiments, a bifunctional or polyfunctional alcohol is used in the polymerization process. Preferably, the diol is, for example, 1,2-propylene glycol, ethylene glycol, diethylene glycol, triethylene glycol, 1,3-propylene glycol, dipropylene glycol, tripropylene glycol, neopentyl glycol, 2-methyl-1,3-propylene glycol, isosorbide, 2,3-butanediol, butylethylpropanediol, hydrogenated bisphenol-A, or a diol such as ethoxylated / propopoxylated bisphenol A. In some embodiments, in addition to the bifunctional or polyfunctional alcohol, a monoalcohol such as 2-ethylhexanol or benzyl alcohol and a polyol such as glycerol or trimethylolpropane can be used. In some embodiments, other mono-, di-, and polyhydric alcohols can be used as well.

[0072] In some embodiments, the polyester can be produced using the diol alone, or a combination of the diol and / or monoalcohol and polyhydric alcohol.

[0073] In some embodiments, an inhibitor to prevent radical polymerization can be added during polycondensation. For example, an unsaturated polyester resin can be prepared in the presence of hydroquinone, 2-methylhydroquinone, benzoquinone, 2-methylbenzoquinone, or other substituted hydroquinone or quinone as an inhibitor.

[0074] In some embodiments, an esterification catalyst and / or an isomerization catalyst can be used during polycondensation.

[0075] In some embodiments, the non-volatile diluent is selected from the group of acrylates and methacrylates. Of these two, methacrylate is preferred as an acrylate, but methacrylate also typically has strong skin sensitization, resulting in a need for operator protection.

[0076] In some embodiments, after the synthesis of the DCPD-modified polyester, the modified polyester can be diluted in a reactive diluent. As suitable diluents, all commercially available (meth)acrylates can be used. Such (meth)acrylates include hydroxyethyl methacrylate (HEMA), hydroxypropyl methacrylate (HPMA), hydroxyethyl acrylate (HEA), hydroxypropyl acrylate (HPA), glycerol formal (meth)acrylate, butyl methacrylate, hexyl (meth)acrylate, tert-butyl methacrylate, benzyl (meth)acrylate, cyclohexyl (meth)acrylate, tert-butyl cyclohexyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, trimethylolpropane tri (meth)acrylate, PEG200 di (meth)acrylate, 1,4-butanediol di (meth)acrylate, 1,3-butanediol di (meth)acrylate, 2,3-butanediol di (meth)acrylate, 1,6-hexanediol di (meth)acrylate and its isomers, ethylene glycol di (meth)acrylate, diethylene glycol di (meth)acrylate, triethylene glycol di (meth)acrylate, glycerol di (meth)acrylate, trimethylolpropane di (meth)acrylate, neopentyl glycol di (meth)acrylate, dipropylene glycol di (meth)acrylate, tripropylene glycol di (meth)acrylate, PPG250 di (meth)acrylate, tricyclodecane dimethylol di (meth)acrylate, 1,10-decanediol di (meth)acrylate and / or tetraethylene glycol dimethacrylate. Preferred difunctional reactive diluents are 1,4-butanediol di (meth)acrylate, neopentyl glycol di (meth)acrylate, PEG400 di (meth)acrylate, triethylene glycol di (meth)acrylate and / or tripropylene glycol di (meth)acrylate.

[0077] In some embodiments, in addition to (meth)acrylates, itaconate diluents such as dimethyl itaconate, diethyl itaconate, diisopropyl itaconate, di-n-propyl itaconate, and dibutyl itaconate can be used. Among these diluents, dimethyl itaconate is preferred. Preferably, the itaconate diluent is used in combination with a (meth)acrylate diluent. More preferably, the itaconate diluent is used in combination with a methacrylate diluent.

[0078] In some embodiments, the total amount of the (meth)acrylate and the itaconate diluent is at least 5 to 95% by weight, preferably 10 to 70% by weight, more preferably 20 to 60% by weight, most preferably 30 to 50% by weight, for example 40% by weight, of the total amount of the unsaturated polyester resin composition. The preferred concentration of the polyfunctional (meth)acrylate in the present invention is 5 to 95% by weight, preferably 5 to 85% by weight of the total amount of the unsaturated polyester resin composition. More preferably 5 to 80% by weight, still more preferably 5 to 75% by weight, even more preferably 5 to 70% by weight, even more preferably 5 to 65% by weight, still more preferably 5 to 60% by weight, still more preferably 10 to 60% by weight, still more preferably 20 to 60% by weight, for example 20% by weight, 25% by weight, 30% by weight, 40% by weight, 45% by weight, 50% by weight, 55% by weight. These amounts are the total amounts of one type of reactive diluent or a combination of two or more reactive diluents.

[0079] A low volatility diluent is preferred, but in some embodiments, a small amount of volatile diluent may be present. By "small amount" is meant less than 10.0% of the total formulation, more preferably less than 5.0%, even more preferably less than 2.0%, and even more preferably less than 1.0%. Examples of volatile diluents include styrene, α-methylstyrene, vinyltoluene, and methyl methacrylate. Thus, in some embodiments, the amount of volatile organic compound (VOC) is less than 10% by weight of the total amount of the unsaturated polyester resin composition. Preferably less than 5% by weight, more preferably less than 2% by weight, and even more preferably less than 1% by weight. More specifically, in some embodiments, the amount of styrene, α-methylstyrene, vinyltoluene, and / or methyl methacrylate is less than 10% by weight of the total amount of the unsaturated polyester resin composition, preferably less than 5% by weight, more preferably less than 2% by weight, and even more preferably less than 1% by weight.

[0080] In some embodiments, the unsaturated polyester resin composition may further contain various additives such as inhibitors, accelerators, promotors, fillers, pigments, dyes, UV stabilizers, thixotropic agents, defoaming agents, photoinitiators, and / or other additives. Suitable compounds are further listed below.

[0081] In some embodiments, the unsaturated polyester resin composition may contain an accelerator. As accelerators, typically transition metal compounds such as vanadium, iron, manganese, copper, nickel, molybdenum, tungsten, cobalt, and chromium compounds are used. Preferred transition metals are V, Cu, Co, Mn, and Fe. The transition metal may be present as a carboxylate salt, may be a polymer, or may be complexed with a ligand. Such complexes include Borchi OxyCure®, DriCat® 2700F, and Nuodex DryCoat. The accelerator can be based on one transition metal or a combination of multiple transition metals.

[0082] In some embodiments, the unsaturated polyester resin composition may contain an activator. Examples of the activator include acetylacetone, N,N-dimethylacetoacetamide, N,N-diethylacetoacetamide, acetyl esters, and aromatic amines such as N,N-dimethylaniline, N,N-diethylaniline, N,N-diisopropanol-para-toluidine, N,N-dimethyl-p-toluidine, and xylidines such as N,N-bis(2-hydroxyethyl)xylidine and N,N-dimethyl-p-xylidine. Also, it may contain an alkali and an alkali salt.

[0083] In some embodiments, the unsaturated polyester resin composition may further contain a radical inhibitor. The radical inhibitor is preferably selected from the group consisting of phenol compounds, benzoquinones, hydroquinones, catechols, stable radicals, and / or phenothiazines. The amount of the radical inhibitor that can be added is quite wide, and it may be selected using the gel time to be achieved as the first index.

[0084] Preferable examples of radical inhibitors that can be used in embodiments of the unsaturated polyester resin composition include, for example, 2-methoxyphenol, 4-methoxyphenol, 2,6-di-t-butyl-4-methylphenol, 2,6-di-t-butylphenol, 2,4,6-trimethylphenol, 2,4,6-tris(dimethylaminomethyl)phenol, 4,4′-thio-bis(3-methyl-6-t-butylphenol), 4,4′-isopropylidenediphenol, 2,4-di-t-butylphenol, 6,6′-di-t-butyl-2,2′-methylenedi-p-cresol, hydroquinone, 2-methylhydroquinone, 2-t-butylhydroquinone, 2,5-di-t-butylhydroquinone, 2,6-di-t-butylhydroquinone, 2,6-dimethylhydroquinone, 2,3,5-trimethylhydroquinone, catechol, 4-t-butylcatechol, 4,6-di-t-butylcatechol, benzoquinone, 2,3,5,6-tetrachloro-1,4-benzoquinone, methylbenzoquinone, 2,6-dimethylbenzoquinone, naphthoquinone, 1-oxyl-2,2,6,6-tetramethylpiperidine, 1-oxyl-2,2,6,6-tetramethylpiperidin-4-ol (a compound also called TEMPOL), 1-oxyl-2,2,6,6-tetramethylpiperidin-4-one (a compound also called TEMPON), 1-oxyl-2,2,6,6-tetramethyl-4-carboxyl-piperidine (a compound also called 4-carboxy-TEMPO), 1-oxyl-2,2,5,5-tetramethylpyrrolidine, 1-oxyl-2,2,5,5-tetramethyl-3-carboxypyrrolidine (also called 3-carboxy-PROXYL), galvinoxyl, aluminum-N-nitrosophenylhydroxylamine, diethylhydroxylamine, phenothiazine and / or derivatives, or combinations of these compounds.

[0085] In some embodiments, the amount of the radical inhibitor relative to the total amount of the unsaturated polyester and the reactive diluent present in the unsaturated polyester resin composition is in the range of 0.0001 to 10.0% by weight, more preferably in the range of 0.001 to 1.0% by weight. Although it depends on the type of inhibitor selected, those skilled in the art can understand that the content of the inhibitor leads to good results according to the present invention.

[0086] The present invention further relates to a method for radically curing the unsaturated polyester resin composition of the present invention, which comprises curing by adding an initiator to the resin composition and activating it as described above. Preferably, the curing is carried out at a temperature in the range of -20 to +200°C, preferably in the range of -20 to +100°C, and most preferably in the range of -10 to +60°C (so-called low-temperature curing).

[0087] In some embodiments, the initiator can be a photoinitiator, a thermal initiator, a redox initiator, and / or a combination thereof.

[0088] As used herein, a photoinitiator can initiate curing upon irradiation, and photoinitiation means curing using irradiation with light of an appropriate wavelength (light irradiation). This is also called photocuring.

[0089] In some embodiments, a sensitizer may be added to the photoinitiator forming the photoinitiating system.

[0090] In some embodiments, it can be used as a mixture with a photoinitiator, optionally in combination with one or more sensitizers as desired.

[0091] In some embodiments, the photoinitiator can be selected from a number of photoinitiators known to those skilled in the art. A vast number of suitable photoinitiators are described, for example, in "Chemistry and Technology of UV and EB formulation", 2nd Edition, Volume 3, K. Dietliker and J.V. Crivello (SITA Technology, London; 1998), which is hereby incorporated by reference.

[0092] In some embodiments, the thermal initiator can be selected from azo compounds such as azoisobutyronitrile (AIBN), C-C labile compounds such as benzopinacol, peroxides, and mixtures thereof. In some embodiments, the thermal initiator is preferably an organic peroxide or a combination of two or more organic peroxides.

[0093] In some embodiments, the redox initiator is preferably a combination of an organic peroxide and at least one of the above co-initiators. Suitable peroxides include hydroperoxides, peroxicarbonates (formula -OC(O)OO-), peroxy esters (formula -C(O)OO-), diacyl peroxides (formula -C(O)OOC(O)-), dialkyl peroxides (formula -OO-), etc.

[0094] The present invention further relates to a cured product or a structural part prepared from the unsaturated polyester resin composition as described above by curing with the initiator as described above.

[0095] In some embodiments, surface curing is carried out outdoors, for reasons such as for use in molding using an open mold.

[0096] As used herein, "structural resin" or "structural resin composition" can provide a structural part (structural component) suitable for application to a structure. Preferably, such a resin composition is non-aqueous. However, it may preferably contain water generated mainly from the reaction during resin preparation in an amount of 5% by weight or less. In this specification, "structural part (structural component)" is considered to have a thickness of 0.5 mm or more after curing and appropriate mechanical properties.

[0097] End segments to which the resin composition according to the present invention can be applied are, for example, automotive parts, boats, chemical anchors, roofs, structures, containers, linings, pipes, tanks, floor materials, and windmill blades.

[0098] The present invention further relates to a gel coat composition prepared from an unsaturated polyester resin composition as described above. The gel coat can be applied in an open mold.

[0099] A further aspect of the present invention provides the unsaturated polyester resin composition described herein, or an embodiment thereof, for manufacturing a structural part (component) in an open mold.

[0100] A further aspect of the present invention is a structural part prepared using the unsaturated polyester resin composition described herein, or an embodiment thereof, preferably a structural part in an open mold.

[0101] A further aspect of the present invention provides the unsaturated polyester resin composition described herein, or an embodiment thereof, for manufacturing a gel coat composition.

[0102] A further aspect of the present invention provides applying a gel coat in an open mold using the unsaturated polyester resin composition described herein, or an embodiment thereof.

[0103] A further aspect of the present invention provides a gel coat composition containing the unsaturated polyester resin composition described herein, or an embodiment thereof, preferably applied to an open mold.

[0104] A further aspect of the present invention provides a method for preparing an unsaturated polyester resin composition, preferably an unsaturated polyester resin composition according to the embodiments described herein, the method comprising the following steps. Step of forming a polyester from at least the following: a) a reagent containing itaconic acid and / or itaconic anhydride; b) a reagent containing maleic acid, maleic anhydride, and / or fumaric acid; c) a reagent containing dicyclopentadiene (DCPD); and d) a reagent containing at least one bifunctional or polyfunctional alcohol; A production method comprising the step of mixing the obtained polyester with a (meth)acrylate compound and optionally an itaconate compound to obtain an unsaturated polyester resin composition, The total weight of the reagent a) is 10% by weight or more, preferably 20% by weight or more, of the total weight of the dibasic acids and anhydrides used in the unsaturated polyester resin composition.

[0105] In some embodiments, the method includes the step of forming a reaction mixture from reagent b), reagent c) and optionally reagent a) before forming the polyester. In embodiments where the reaction mixture is formed from reagent b) and reagent c), the polyester can be formed from the obtained reaction mixture, reagent a) and reagent d). In embodiments where the reaction mixture is formed from reagent b), reagent c) and reagent a), the polyester can be formed from the obtained reaction mixture and reagent d).

[0106] In some embodiments, water is added to reagent a) and / or b). In particular, when reagent a) or b) contains an anhydride, water is added.

[0107] In some embodiments, the unsaturated polyester resin composition may contain any suitable compound listed as an embodiment of the above unsaturated polyester resin composition.

[0108] In some embodiments, the reaction mixture may contain an inhibitor.

[0109] In some embodiments, one reagent can form a reaction mixture in the absence of reagent a), and reagent d) can be added together with reagent a) to form a polyester. Also, in these embodiments, the total weight of itaconic acid and itaconic anhydride is 10% by weight or more, preferably 20% by weight or more, of the total weight of the dibasic acids and anhydrides used in the unsaturated polyester resin composition.

[0110] In some embodiments, when reagent a) and / or b) contains an anhydride, reagent c) is added to reagent a) and / or b) to form a reaction mixture, and preferably reagent a) and / or reagent b) are hydrolyzed before reagent c) is added. Thereby, the reaction can be controlled and the heat generated during the reaction can be controlled.

[0111] In some embodiments, when reagent a) and / or b) contains an anhydride, reagent a) and / or reagent b) are added to reagent c) to form a reaction mixture, and preferably reagent a) and / or reagent b) are hydrolyzed before being added to reagent c). This method can provide resins having similar chemical and physical properties, but is not preferred from the viewpoint of safety.

[0112] In some embodiments, reagent a) and / or reagent b) are hydrolyzed by heating to a temperature of at least 130°C to 140°C, preferably 135°C, in the presence of water before forming the reaction mixture.

[0113] In some embodiments, one or more diols are, for example, propylene glycol, neopentyl glycol, and / or diethylene glycol.

[0114] In some embodiments, the structural units formed by the above method may be the following.

Chemical formula

[0115] The present invention will be further described based on the following examples, but the present invention is not limited to the following examples.

Examples

[0116] Usage method To test the mechanical properties and HDT of the cured resin, samples were prepared according to the following method, and molded products were produced using a mold consisting of two glass plates coated with wax and a rubber spacer with a thickness of 4 mm. The resin to be tested was thoroughly mixed with 0.1% Byk555 (air release agent), 1.0% Accelerator NL-49P (Nouryon), and 1.5% Butanoc M-50, degassed, and then injected into the mold. After 24 hours, the cured resin was demolded and further post-cured at 80°C for 24 hours.

[0117] Tensile properties were measured according to ISO527-2. The heat distortion temperature (HDT) was measured according to ISO75-A.

[0118] Experiment 1: Preparation of DCPD-polyester A (Example 1) The main chain A was prepared according to the following procedure. A container equipped with a filling column, a temperature measuring device, and an inert gas inlet was charged with a mixture of maleic anhydride (10.0 mol), itaconic acid (10.0 mol), water (10 mol), and an inhibitor, and heated to 135 - 140 °C. To this mixture, DCPD (8.0 mol) was added while adjusting the rate to avoid a temperature rise due to the exothermic reaction. The addition was carried out over about 30 minutes. Under these conditions, DCPD reacts with the acid groups of maleic acid and itaconic acid to form DCPD-maleic acid ester and DCPD-itaconic acid ester. After the addition of DCPD was completed, the mixture was left at 135 - 140 °C for 1 hour, and then neopentyl glycol (13.0 mol) and propylene glycol (4.0 mol) were added. The mixture was heated to 140 °C and then the temperature was raised to 190 °C over two and a half hours. The mixture was maintained at a temperature of 190 - 200 °C until the distillation of water ceased. The filled column was removed and the mixture was maintained under reduced pressure (about 100 mbar) until the acid value reached a value of about 30 - 35 mg KOH / g resin. Then, the vacuum was relieved with an inert gas and the mixture was cooled.

[0119] Experiment 2: Preparation of DCPD-polyester B (Comparative Example 1) The main chain B was prepared according to the following procedure. A mixture of maleic anhydride (20.0 mol), water (10 mol) and an inhibitor was placed in a container equipped with a filling column, a temperature measuring device and an inert gas inlet, and heated to 135 - 140 °C. To this mixture, DCPD (8.0 mol) was added while adjusting the rate to avoid a temperature rise due to the exothermic reaction. The addition was carried out over about 30 minutes. Under these conditions, DCPD reacts with the acid groups of maleic acid to form DCPD - maleic acid ester. After the addition of DCPD was completed, the mixture was left at 135 - 140 °C for 1 hour, and then neopentyl glycol (13.0 mol) and propylene glycol (4.0 mol) were added. The mixture was heated to 140 °C and then heated for two and a half hours to raise the temperature to 190 °C. The mixture was maintained at a temperature of 190 - 200 °C until the distillation of water stopped. The filled column was removed, and the mixture was maintained under reduced pressure (about 100 mbar) until the acid value reached a value of about 30 - 35 mg KOH / g resin. Then, the vacuum was relieved with an inert gas and the mixture was cooled.

[0120] Experiment 3: Preparation of benzyl alcohol - polyester C (Comparative Example 2) The main chain C was prepared according to the following procedure. A mixture of maleic anhydride (10.0 mol), itaconic acid (10 mol) and an inhibitor was placed in a container equipped with a filling column, a temperature measuring device and an inert gas inlet, and heated to 135 - 140 °C. To this mixture, benzyl alcohol (8.0 mol) was added and reacted for about 1 hour. Subsequently, neopentyl glycol (13.0 mol) and propylene glycol (4.0 mol) were added. The mixture was heated to 140 °C and then heated for two and a half hours to raise the temperature to 190 °C. The mixture was maintained at a temperature of 190 - 200 °C until the distillation of water stopped. The filled column was removed, and the mixture was maintained under reduced pressure (about 100 mbar) until the acid value reached a value of about 30 - 35 mg KOH / g resin. Then, the vacuum was relieved with an inert gas and the mixture was cooled.

[0121] Experiment 4: Preparation of DCPD - polyester D (Example 2) The main chain D was prepared according to the following procedure. A mixture of maleic anhydride (8.0 mol), itaconic acid (12.0 mol), water (10 mol) and an inhibitor was placed in a container equipped with a filling column, a temperature measuring device and an inert gas inlet, and heated to 135 - 140 °C. DCPD (8.0 mol) was added to this mixture while adjusting the rate to avoid a temperature rise due to the exothermic reaction. The addition was carried out over about 30 minutes. Under such conditions, DCPD reacts with the acid groups of maleic acid and itaconic acid to form DCPD-maleic acid ester and DCP-itaconic acid ester. After the addition of DCPD was completed, the mixture was left at 135 - 140 °C for 1 hour, and then neopentyl glycol (8.8 mol) and propylene glycol (8.8 mol) were added. The mixture was heated to 140 °C and then the temperature was raised to 190 °C over two and a half hours. The mixture was maintained at a temperature of 190 - 200 °C until the distillation of water ceased. The filling column was removed and the mixture was maintained under reduced pressure (about 100 mbar) until the acid value reached a value of about 30 - 35 mg KOH / g resin. Then, the vacuum was relieved with an inert gas and the mixture was cooled.

[0122] Experiment 5: Preparation of DCPD-polyester E (Example 3) The main chain E was prepared according to the following procedure. A mixture of maleic anhydride (4.0 mol), itaconic acid (16.0 mol), water (10 mol) and an inhibitor was placed in a container equipped with a filling column, a temperature measuring device and an inert gas inlet, and heated to 135 - 140 °C. To this mixture, DCPD (12.0 mol) was added while adjusting the rate to avoid a temperature rise due to the exothermic reaction. The addition was carried out over about 30 minutes. Under these conditions, DCPD reacts with the acid groups of maleic acid and itaconic acid to form DCPD - maleic acid ester and DCP - itaconic acid ester. After the addition of DCPD was completed, the mixture was left at 135 - 140 °C for 1 hour, and then neopentyl glycol (12.0 mol) and diethylene glycol (4.0 mol) were added. The mixture was heated to 140 °C and then the temperature was raised to 190 °C over two and a half hours. The mixture was maintained at a temperature of 190 - 200 °C until the distillation of water ceased. The filling column was removed and the mixture was maintained under reduced pressure (about 100 mbar) until the acid value reached a value of about 30 - 35 mg KOH / g resin. Then, the vacuum was relieved with an inert gas and the mixture was cooled. This experiment shows that a large excess amount of DCPD can be used compared to the amount of maleic acid.

[0123] Experiment 6 (Comparative Example 3) A mixture of itaconic acid, an inhibitor and water was placed in a container equipped with a filling column, a temperature measuring device and an inert gas inlet, and an attempt was made to heat it to 135 - 140 °C. With equimolar amounts of itaconic acid and water, the mixture remained solid and effective stirring could not be carried out. By increasing the amount of water, a stirrable suspension could be produced, but in this case, the water began to boil below 110 °C. Therefore, when starting only with itaconic acid, an inhibitor and water, the conditions necessary for safe DCPD addition could not be reached.

[0124] Experiment 7 (Comparative Example 4) A mixture of 5 moles of itaconic acid, 1 mole of neopentyl glycol, 1 mole of diethylene glycol, an inhibitor, and water was heated to 135 - 140 °C in a container equipped with a filling column, a temperature measuring device, and an inert gas inlet. To this suspension, 3 moles of DCPD were added over about 40 minutes. Unlike the experiment in the presence of maleic acid, no exotherm was observed during the reaction. After the addition was complete, the mixture was placed in and maintained at 135 - 140 °C for an additional 2 hours. Unlike the experiment in the presence of maleic acid, the mixture remained turbid. After stirring was stopped, the mixture separated into two layers. One of the layers was an unreacted DCPD layer, and the experiment was stopped. This experiment shows that the presence of maleic acid is necessary for the successful addition of DCPD to itaconic acid.

[0125] Experiment 8 The main chains prepared in Experiments 1 - 3 were diluted with a combination of triethylene glycol dimethacrylate (TRGDMA) and dimethyl itaconate (DMI). To cure these resins, they were mixed with 0.3% cobalt octoate solution (10% Co), 0.1% copper naphthenate solution (8% Cu), 0.5% N,N - diethyl - acetoxyacetamide, and 2.0% Butanox LPT - IN. These formulations were poured into an open mold to form a layer about 4 mm thick. After 24 hours, the surface tackiness was evaluated by touching by hand, and the Barcol hardness was measured. The results are shown in Table 1. Only the resin having Main Chain A cured properly after 24 hours.

Table 1

[0126] Experiment 9 The DCPD-polyesters prepared in Experiments 1 to 5 were diluted with different combinations of different methacrylate compounds and dimethyl itaconate as diluents. The viscosities of these resins were measured, and then the resins were cured with 1.0% Accelerator NL-49P and 1.5% Butanox M-50 (both from Nouryon), and post-cured at 80 °C for 24 hours. Subsequently, the HDT and tensile properties of these resins were measured. The results in Table 2 show that the resins of the present invention (main chains A, D, and E) have appropriate viscosities, HDTs, and tensile properties. The resin having main chain B of the comparative example has a high viscosity and too low an HDT. The resin having main chain C of the comparative example has a low HDT and a low elastic modulus. These tendencies of the main chains were observed for all combinations of the diluents tested.

Table 2

Claims

1. An unsaturated polyester resin composition containing a (meth)acrylate compound and a polyester formed from the following reagents, a) a reagent containing itaconic acid and / or itaconic anhydride; b) a reagent containing maleic acid, maleic anhydride, and / or fumaric acid; c) a reagent containing dicyclopentadiene (DCPD); and d) a reagent containing at least one bifunctional or polyfunctional alcohol; The total weight of the itaconic acid and the itaconic anhydride is 10% by weight or more of the total weight of the dibasic acids and anhydrides used in the unsaturated polyester resin composition. An unsaturated polyester resin composition.

2. The unsaturated polyester resin composition according to Claim 1, wherein the weight of the volatile organic compound (VOC) is less than 10% by weight of the total weight of the unsaturated polyester resin composition.

3. The unsaturated polyester resin composition according to Claim 1 or 2, wherein the total weight of styrene, α-methylstyrene, vinyltoluene, and / or methyl methacrylate is less than 10% by weight of the total weight of the unsaturated polyester resin composition.

4. The unsaturated polyester resin composition according to any one of Claims 1 to 3, wherein the weight of the (meth)acrylate compound is 5 to 95% by weight of the total weight of the unsaturated polyester resin composition.

5. The unsaturated polyester resin composition according to any one of Claims 1 to 4, further comprising an itaconic acid ester compound.

6. The unsaturated polyester resin composition according to Claim 5, wherein the total weight of the (meth)acrylate compound and the itaconate compound is 5 to 95% by weight of the total weight of the unsaturated polyester resin composition.

7. The unsaturated polyester resin composition according to any one of Claims 1 to 6, wherein the addition amount of the DCPD is 10% by weight or more of the total weight of the polyester.

8. The unsaturated polyester resin composition according to any one of Claims 1 to 7, further comprising a transition metal salt or a transition metal complex.

9. The unsaturated polyester resin composition according to any one of Claims 1 to 8, further comprising a cobalt salt or a cobalt polymer.

10. Use of the unsaturated polyester resin composition according to any one of Claims 1 to 9 as a material used to constitute a part of a structure.

11. ​ Use of the unsaturated polyester resin composition according to any one of claims 1 to 9 as a gel coat composition or a coating composition.

12. Use according to claim 10 or claim 11 in an open type.

13. A method for producing an unsaturated polyester resin composition, the production method comprising: A step of forming a polyester from the following reagents, a) A reagent containing itaconic acid and / or itaconic anhydride; b) A reagent containing maleic acid, maleic anhydride, and / or fumaric acid; c) A reagent containing dicyclopentadiene (DCPD); and d) A reagent containing at least one bifunctional or polyfunctional alcohol; And a step of obtaining an unsaturated polyester resin composition by mixing the obtained polyester with a (meth)acrylate compound, The total weight of the itaconic acid and the itaconic anhydride is 10% by weight or more of the total weight of the dibasic acids and anhydrides used in the unsaturated polyester resin composition.

14. The method according to claim 13, including a step of forming a reaction mixture from reagent b) and reagent c), or a step of forming a reaction mixture from reagent a), reagent b), and reagent c) before forming the polyester.

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