Rosin-modified unsaturated polyester, rosin-modified unsaturated polyester composition, and molded body

Abstract

The present invention aims to provide a rosin-modified unsaturated polyester capable of forming a cured product excellent in both surface hardness and water resistance. The rosin-modified unsaturated polyester of the present invention is characterized in that it has a methanol resistance at 25°C of 100 g or less. As the rosin-modified unsaturated polyester, a polycondensate of raw material compounds including a carboxylic acid (X) containing a rosin (a) and an α,β-unsaturated dicarboxylic acid (b) and a polyhydric alcohol (Y) can be suitably used. According to the present invention, a rosin-modified unsaturated polyester capable of forming a cured product excellent in both surface hardness and water resistance can be provided.

Description

Technical Field

[0001] This invention relates to rosin-modified unsaturated polyester, rosin-modified unsaturated polyester compositions, and molded articles. Background Technology

[0002] Previously, cured unsaturated polyester compositions were widely used as molded parts in various applications such as buildings, automobiles, aircraft, ships and electronic equipment due to their excellent moldability and appearance.

[0003] In recent years, from an environmental perspective, there has been a growing demand for fiber-reinforced plastics (FRPs) with excellent lightweight properties and mechanical strength in fields such as ship hulls, bathtubs, building materials, and industrial equipment. In FRPs, unsaturated polyester compositions are used as adhesives to integrate the reinforcing fibers. The manufacture of FRPs involves impregnating the reinforcing fibers with an unsaturated polyester composition and then curing it.

[0004] The unsaturated polyester composition comprises an unsaturated polyester, a free-radical polymerizable monomer, and a polymerization initiator or curing agent used as needed. Generally, an unsaturated polyester can be obtained by polycondensation of a carboxylic acid containing α,β-unsaturated dicarboxylic acid and a polyol. Then, by copolymerizing the unsaturated polyester and the free-radical polymerizable monomer, the unsaturated polyester composition can be cured, thereby obtaining a molded article.

[0005] Patent Document 1 discloses an unsaturated polyester composition comprising an unsaturated polyester and a polymerizable monomer. The unsaturated polyester is composed of an acid component and an alcohol component. The acid component includes aromatic dicarboxylic acids, monocarboxylic acids, and unsaturated dicarboxylic acids, and the alcohol component includes polyols with three or more carbon atoms and diols. As monocarboxylic acids, rosin-like compounds and aliphatic monocarboxylic acids with 4 to 36 carbon atoms derived from biomass are used.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 2010-235777 Summary of the Invention

[0009] The problem that the invention aims to solve

[0010] However, in previous unsaturated polyester compositions, the surface hardness and water resistance after curing were not good enough, requiring further improvement.

[0011] Therefore, the object of the present invention is to provide a rosin-modified unsaturated polyester capable of forming a cured product with excellent surface hardness and water resistance. Furthermore, the object of the present invention is to provide a rosin-modified unsaturated polyester composition comprising the above-mentioned rosin-modified unsaturated polyester and a molded article thereof.

[0012] Problem Solving Methods

[0013] In view of the above problems, the inventors have conducted various studies and found that the above problems can be solved by using the following rosin-modified unsaturated polyester.

[0014] The present invention has the following embodiments.

[0015] [1] A rosin-modified unsaturated polyester with a methanol tolerance of less than 100g at 25°C.

[0016] [2] The rosin-modified unsaturated polyester described in [1] above has a softening point of 60°C or higher.

[0017] [3] The rosin-modified unsaturated polyester according to [1] or [2] above is a condensation polymer of a raw material compound containing a carboxylic acid (X) and a polyol (Y), wherein the carboxylic acid (X) includes rosin (a) and α,β-unsaturated dicarboxylic acid (b).

[0018] [4] According to the rosin-modified unsaturated polyester described in [3] above, wherein,

[0019] Rosin class (a) includes at least one of disproportionated rosin and hydrogenated rosin.

[0020] [5] According to the rosin-modified unsaturated polyester described in [3] or [4] above, wherein,

[0021] Polyol (Y) contains polyols (d) with 3 or more members.

[0022] [6] A rosin-modified unsaturated polyester composition comprising:

[0023] Rosin-modified unsaturated polyester as described in any one of [1] to [5] above, and

[0024] Polymerization inhibitor.

[0025] [7] A rosin-modified unsaturated polyester composition comprising:

[0026] Rosin-modified unsaturated polyester as described in any one of [1] to [5] above, and

[0027] Free radical polymerizable monomers.

[0028] [8] According to the rosin-modified unsaturated polyester composition described in [7] above, wherein,

[0029] The free radical polymerizable monomers include at least one of styrene and methylstyrene.

[0030] [9] A molded article comprising a cured product of the rosin-modified unsaturated polyester composition described in [7] or [8] above.

[0031] The effects of the invention

[0032] According to the present invention, rosin-modified unsaturated polyester can be provided that yields a cured product with excellent surface hardness and water resistance. The cured product can be suitably used as a molded article shaped into a desired form. Detailed Implementation

[0033] Rosin-modified unsaturated polyester

[0034] This invention relates to rosin-modified unsaturated polyesters. Preferably, the rosin-modified unsaturated polyesters have a methanol tolerance of less than 100g at 25°C.

[0035] In the rosin-modified unsaturated polyester of the present invention, rosin-based (a) was used as a raw material compound for modification, thereby improving the surface hardness after curing. However, when rosin-based (a) is used alone, not only is it impossible to sufficiently improve the surface hardness after curing, but sometimes the water resistance also decreases.

[0036] In view of this actual situation, the inventors conducted in-depth research and found that, for rosin-modified unsaturated polyester modified by rosin (a), by setting the methanol tolerance to below 100g, a cured product with excellent surface hardness and water resistance can be formed.

[0037] In this invention, the determination of "methanol tolerance," as described below, can be performed by adding methanol (as a lean solvent) dropwise to a reference solution obtained by dissolving rosin-modified unsaturated polyester in toluene, and measuring the amount of methanol required to precipitate the rosin-modified unsaturated polyester until a white turbidity is formed. The more hydrophilic polar groups such as carboxyl and hydroxyl groups present in the rosin-modified unsaturated polyester, the greater its polarity. Thus, the greater the polarity, the less likely the rosin-modified unsaturated polyester is to precipitate in the reference solution after the addition of methanol, exhibiting a tendency for increased methanol tolerance. Therefore, methanol tolerance can be used as an indicator of the degree of esterification of rosin-modified unsaturated polyester.

[0038] Furthermore, by setting the methanol tolerance to 100g or less, the degree of esterification can be increased by fully esterifying the carboxyl groups of the carboxylic acid component of the rosin-based (a) constituting the rosin-modified unsaturated polyester with the hydroxyl groups of the polyol component. Based on this rosin-modified unsaturated polyester modified with rosin-based (a) and having an increased degree of esterification by setting the methanol tolerance to 100g or less, a rosin-modified unsaturated polyester composition capable of forming a cured product with excellent surface hardness and water resistance can be provided. The cured product can be suitably used as a molded article molded into a desired shape.

[0039] The methanol tolerance of rosin-modified unsaturated polyester at 25°C is preferably less than 100g, more preferably less than 80g, more preferably less than 75g, more preferably less than 70g, more preferably less than 60g, and more preferably less than 45g.

[0040] The methanol tolerance of rosin-modified unsaturated polyester at 25°C is preferably 25g or higher. By setting the methanol tolerance to 25g or higher, the oil resistance (oil repellency) of rosin-modified unsaturated polyester can be improved, thereby reducing the intrusion of oil into the cured product of rosin-modified unsaturated polyester.

[0041] The methanol tolerance of rosin-modified unsaturated polyester at 25°C can be determined according to the following steps. First, dissolve 5g of rosin-modified unsaturated polyester in 50mL of toluene in a transparent glass conical flask (100mL capacity, preferably according to JIS R3503 (1994)) to obtain a reference solution. While stirring the reference solution at 25°C, methanol is added dropwise to the reference solution, and the mass (g) of methanol added until turbidity appears in the reference solution is calculated. This mass (g) of methanol is taken as the methanol tolerance of the rosin-modified unsaturated polyester at 25°C. It should be noted that when the conical flask is placed on newspaper, with the newspaper in contact with the conical flask, and the text (10-point font) printed on the newspaper is visually discernible through the reference solution in the conical flask, the point at which the text cannot be visually discerned due to the turbidity of the reference solution is judged as "turbidity has appeared in the reference solution".

[0042] The softening point of the rosin-modified unsaturated polyester is preferably 50°C or higher, more preferably 55°C or higher, more preferably 60°C or higher, and even more preferably 81°C or higher. The softening point of the rosin-modified unsaturated polyester is more preferably 130°C or lower. By setting the softening point of the rosin-modified unsaturated polyester to 50°C or higher, the rosin-modified unsaturated polyester exhibits higher surface hardness after curing. By setting the softening point of the rosin-modified unsaturated polyester to 130°C or lower, the solubility of the rosin-modified unsaturated polyester in the rosin-modified unsaturated polyester composition for free radical polymerizable monomers can be improved.

[0043] It should be noted that the softening point of rosin-modified unsaturated polyester is set as the value determined according to ASTM D6090 (1997). The above determination can be performed using a measuring device such as the Mettler Toledo "Dropping Point System DP70". When using the above measuring device, the softening point can be determined, for example, as described below. First, a stainless steel cup with a diameter of 10 mm at the top, a hole with a diameter of 6.35 mm at the bottom, and a depth of 10 mm is filled with rosin-modified unsaturated polyester. After placing the cup in the measuring device, the temperature is increased from 40°C at a rate of 3°C / minute. The temperature at which the rosin-modified unsaturated polyester is detected by a detector positioned 19 mm vertically below the hole at the bottom of the cup is measured, and this temperature is taken as the softening point.

[0044] The rosin-modified unsaturated polyester is preferably a condensation polymer (reaction product) of a raw material compound comprising a carboxylic acid (X) and a polyol (Y), wherein the carboxylic acid (X) comprises rosin (a) and an α,β-unsaturated dicarboxylic acid (b). The rosin-modified unsaturated polyester can be obtained by esterifying the carboxyl group of the carboxylic acid (X) with the hydroxyl group of the polyol (Y). The raw material compounds constituting the rosin-modified unsaturated polyester will be described in turn below.

[0045] [Carboxylic acids (X)]

[0046] The raw material compounds constituting rosin-modified unsaturated polyester include carboxylic acids (X). Preferably, the carboxylic acids (X) include rosin compounds (a) and α,β-unsaturated dicarboxylic acids (b).

[0047] (Rosin type (a))

[0048] Examples of rosin class (a) include unmodified rosin (unmodified rosin) and modified rosin (rosin derivatives). Rosin class (a) can be used alone or in combination of two or more.

[0049] Examples of unmodified rosin include natural rosin such as gum rosin, tall oil rosin, and wood rosin; as well as purified rosin obtained by purifying natural rosin. Gum rosin is preferred as a natural rosin. Purified rosin can be obtained by purifying natural rosin using known purification methods such as distillation, extraction, recrystallization, and adsorption. Unmodified rosin can be used alone or in combination with other types.

[0050] Natural rosin is a natural resin primarily composed of resin acids. Natural rosin contains resin acids with conjugated double bonds. Additionally, natural rosin may also contain resin acids without conjugated double bonds. Examples of resin acids with conjugated double bonds include abietic acid, longleaf abietic acid, neoabietic acid, and L-piperidine. Examples of resin acids without conjugated double bonds include dehydroabietic acid, dihydroabietic acid, and tetrahydroabietic acid. Resin acids with and without conjugated double bonds can be used individually or in combination.

[0051] Modified rosin is a modified form of the unmodified rosin described above. Examples of modified rosin include acid-modified rosin and stabilized rosin.

[0052] Acid-modified rosin can be obtained, for example, by adding α,β-unsaturated carboxylic acids to unmodified rosin using the Diels-Alder reaction or similar methods. Examples of α,β-unsaturated carboxylic acids include α,β-unsaturated carboxylic acids and their anhydrides. Specifically, examples include fumaric acid, maleic acid, maleic anhydride, itaconic acid, citraconic acid, citraconic anhydride, acrylic acid, and methacrylic acid. α,β-unsaturated carboxylic acids can be used alone or in combination of two or more.

[0053] Stabilized rosin is a rosin modifier that has undergone stabilization treatment on unmodified rosin. Stabilization treatment can be performed to reduce or eliminate the conjugated double bonds in the resin acids mentioned above. Examples of stabilization treatments include hydrogenation treatment, disproportionation treatment, and polymerization treatment.

[0054] Therefore, examples of stabilized rosin include hydrogenated rosin, disproportionated rosin, and polymerized rosin. Stabilized rosin can be used alone or in combination of two or more types.

[0055] Hydrogenated rosin can be obtained, for example, by hydrogenating unmodified rosin in the presence of a hydrogenation catalyst. Alternatively, hydrogenated rosin can also be obtained by hydrogenating polymerized rosin. Disproportionated rosin can be obtained, for example, by disproportionating unmodified rosin in the presence of a disproportionation catalyst. Polymerized rosin is a polymer of unmodified rosin. Polymerized rosin can be obtained by polymerizing unmodified rosin in the presence of a polymerization catalyst.

[0056] As for rosin (a), modified rosin is preferred, hydrogenated rosin and disproportionated rosin are more preferred, and disproportionated rosin is even more preferred. Thus, rosin-modified unsaturated polyesters with sufficient unsaturated bonds capable of copolymerizing with free radical polymerizable monomers described later can be obtained, and rosin-modified unsaturated polyesters can exhibit higher surface hardness and water resistance after curing.

[0057] For example, when α,β-unsaturated dicarboxylic acids (b) are used as carboxylic acids (X) to adequately introduce unsaturated bonds into rosin-modified unsaturated polyesters, sometimes the α,β-unsaturated dicarboxylic acids (b) can add to the rosin (a) via a Diels-Alder reaction, causing the unsaturated bonds in the α,β-unsaturated dicarboxylic acids (b) to disappear. As a result, the chance of copolymerization between the rosin-modified unsaturated polyester and free radical polymerizable monomers is reduced, and sometimes the surface hardness of the cured rosin-modified unsaturated polyester composition containing the rosin-modified unsaturated polyester is insufficient. However, by using modified rosin as the rosin (a), the occurrence of the aforementioned Diels-Alder reaction can be reduced, and the disappearance of the unsaturated bonds in the α,β-unsaturated dicarboxylic acids (b) can be reduced. Therefore, the double bonds from the α,β-unsaturated dicarboxylic acids (b) can remain in the rosin-modified unsaturated polyester. Therefore, it enables rosin-modified unsaturated polyester to copolymerize more reliably with free radical polymerizable monomers, which can improve the surface hardness after curing.

[0058] The content of modified rosin in rosin (a) is preferably 90% by mass or more, more preferably 95% by mass or more, more preferably 98% by mass or more, and particularly preferably 100% by mass.

[0059] Relative to 100 parts by mass of the total amount of carboxylic acids (X) and polyols (Y), the content of rosin (a) in the raw material compound is preferably 20 parts by mass or more, more preferably 30 parts by mass or more, more preferably 40 parts by mass or more, and more preferably 50 parts by mass or more. Relative to 100 parts by mass of the total amount of carboxylic acids (X) and polyols (Y), the content of rosin (a) in the raw material compound is preferably 70 parts by mass or less, more preferably 65 parts by mass or less. By setting the content of rosin (a) to 20 parts by mass or more, the rosin-modified unsaturated polyester can exhibit higher surface hardness and water resistance after curing. By setting the content of rosin (a) to 70 parts by mass or less, a sufficient amount of the raw material compound other than rosin (a) can be used.

[0060] In addition, as will be discussed later, rosin (a) sometimes contains metal atoms as unavoidable impurities, but by setting the content of rosin (a) to 70 parts by mass or less, it is possible to reduce the undesirable increase in the content of metal atoms during the manufacture of rosin-modified unsaturated polyester.

[0061] (α,β-unsaturated dicarboxylic acids (b))

[0062] The raw material compounds constituting the rosin-modified unsaturated polyester include carboxylic acids (X). Preferably, the carboxylic acid (X) includes α,β-unsaturated dicarboxylic acids (b) in addition to the rosin-based compound (a) described above. By using the α,β-unsaturated dicarboxylic acid (b), unsaturated bonds can be introduced into the rosin-modified unsaturated polyester in sufficient quantities.

[0063] Examples of α,β-unsaturated dicarboxylic acids (b) include α,β-unsaturated dicarboxylic acids or their anhydrides. α,β-unsaturated dicarboxylic acids are preferably chain-like dicarboxylic acids having two carboxyl groups in one molecule and an unsaturated bond between the α- and β-carbons of at least one carboxyl group.

[0064] As α,β-unsaturated dicarboxylic acids (b), examples include α,β-unsaturated dicarboxylic acids and their anhydrides, preferably α,β-unsaturated aliphatic dicarboxylic acids and their anhydrides. Specifically, examples include fumaric acid, itaconic acid, maleic acid, succinic acid, citraconic acid, penteneic acid, and their anhydrides. Among these, fumaric acid, maleic acid, and their anhydrides are preferred, maleic acid and maleic anhydride are more preferred, and maleic anhydride is even more preferred. α,β-unsaturated dicarboxylic acids (b) can be used alone or in combination of two or more.

[0065] Relative to 100 parts by mass of the total amount of carboxylic acids (X) and polyols (Y), the content of α,β-unsaturated dicarboxylic acids (b) in the raw material compound is preferably 5 parts by mass or more, more preferably 7 parts by mass or more, and even more preferably 10 parts by mass or more. Relative to 100 parts by mass of the total amount of carboxylic acids (X) and polyols (Y), the content of α,β-unsaturated dicarboxylic acids (b) in the raw material compound is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, even more preferably 30 parts by mass or less, even more preferably 20 parts by mass or less, and even more preferably 18 parts by mass or less. By setting the content of α,β-unsaturated dicarboxylic acids (b) to 5 parts by mass or more, unsaturated bonds can be introduced into the rosin-modified unsaturated polyester in sufficient quantity. Therefore, the rosin-modified unsaturated polyester composition containing the rosin-modified unsaturated polyester exhibits higher surface hardness and water resistance after curing. On the other hand, as the proportion of rosin (a) increases, α,β-unsaturated dicarboxylic acids (b) polymerize with each other, and sometimes the rosin-modified unsaturated polyester gels. To reduce such gelation, it is preferable to set the proportion of α,β-unsaturated dicarboxylic acids (b) to 50 parts by mass or less.

[0066] Furthermore, as described later, rosin (a) sometimes contains metal atoms as unavoidable impurities. When rosin (a) contains a high proportion of 50 parts by mass or more relative to 100 parts by mass of the total amount of carboxylic acids (X) and polyols (Y), the proportion of α,β-unsaturated dicarboxylic acids (b) in the raw material compound is preferably 15 parts by mass or less relative to 100 parts by mass of the total amount of carboxylic acids (X) and polyols (Y). Therefore, in the second esterification step described later, the gelation of the rosin-modified unsaturated polyester due to the metal atoms acting as polymerization catalysts promoting the polymerization of α,β-unsaturated dicarboxylic acids (b) can be reduced.

[0067] (Other carboxylic acids (c))

[0068] The raw material compounds constituting rosin-modified unsaturated polyester include carboxylic acids (X). Preferably, in addition to the rosin-based (a) and α,β-unsaturated dicarboxylic acids (b) described above, the carboxylic acids (X) further include other carboxylic acids (c). It should be noted that the other carboxylic acids (c) mentioned above do not include rosin-based (a) and α,β-unsaturated dicarboxylic acids (b).

[0069] Other carboxylic acids (c) include, for example, monocarboxylic acids (c1) and polycarboxylic acids (c2). These other carboxylic acids (c) can be used alone or in combination of two or more. It should be noted that monocarboxylic acids (c1) do not include rosin (a). Furthermore, polycarboxylic acids (c2) do not include rosin (a) or α,β-unsaturated dicarboxylic acids (b).

[0070] Examples of monocarboxylic acids (C1) include: aliphatic monocarboxylic acids such as acetic acid, propionic acid, butyric acid, valeric acid, hexanoic acid, lauric acid, stearic acid, 2-ethylhexanoic acid, cyclohexanoic acid, and their anhydrides; and aromatic monocarboxylic acids such as benzoic acid, methylbenzoic acid, p-tert-butylbenzoic acid, o-benzoylbenzoic acid, naphtholic acid, and their anhydrides. Among these, aliphatic and aromatic monocarboxylic acids are preferred, and stearic acid, p-tert-butylbenzoic acid, and benzoic acid are more preferred. Furthermore, aromatic monocarboxylic acids are preferred, and p-tert-butylbenzoic acid and benzoic acid are more preferred. A single monocarboxylic acid (C1) may be used, or two or more may be used in combination.

[0071] The polycarboxylic acids (C2) are preferably polycarboxylic acids and their anhydrides that do not contain chain-like unsaturated hydrocarbon chains.

[0072] Examples of polycarboxylic acids (C2) include:

[0073] Oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, octanoic acid, azelaic acid, sebacic acid, dodecanoic acid, tetradecanoic acid, hexadecanoic acid, oxaloacetic acid, methylmalonic acid, dimethylmalonic acid, methylsuccinic acid, 2,2-dimethylsuccinic acid, methylglutaric acid, dimethylglutaric acid, 1,3-propanone dicarboxylic acid, ketoglutaric acid, 2-oxoadipic acid, 4-oxoheptanoic acid, 5-oxoazelaic acid, and their anhydrides, etc., are all chain-type saturated aliphatic dicarboxylic acids.

[0074] Tetrahydrophthalic acid, cyclopropane-1,1-dicarboxylic acid, cyclobutane-1,1-dicarboxylic acid, cyclohexane-1,1-dicarboxylic acid, cyclohexanedicarboxylic acid, and their anhydrides are all cyclic aliphatic dicarboxylic acids.

[0075] Aromatic dicarboxylic acids, including phthalic acid, isophthalic acid, terephthalic acid, phenylene dioxyacetic acid, indane-2,2-dicarboxylic acid, naphthalene-2,6-dicarboxylic acid, naphthalene-2,7-dicarboxylic acid, and their anhydrides; and

[0076] Trimericic acid, pyromellitic acid, and their anhydrides are aromatic tricarboxylic acids or aromatic tetracarboxylic acids.

[0077] As a polycarboxylic acid (C2), isophthalic acid, adipic acid, tetrahydrophthalic acid and their anhydrides are more preferred, and adipic acid, tetrahydrophthalic acid and their anhydrides are even more preferred. A single polycarboxylic acid (C2) may be used alone, or two or more may be used in combination.

[0078] In the categories of monocarboxylic acids (C1) and polycarboxylic acids (C2), other carboxylic acids (C) may contain only monocarboxylic acids (C1). Alternatively, other carboxylic acids (C) may contain both monocarboxylic acids (C1) and polycarboxylic acids (C2).

[0079] [Polyol(Y)]

[0080] The raw material compounds constituting rosin-modified unsaturated polyester preferably include polyol (Y). Polyol (Y) is a polyol having two or more hydroxyl groups in one molecule.

[0081] Examples of polyols (Y) include polyols (d) with three or more members and diols (e). Polyol (Y) preferably contains at least a polyol (d) with three or more members. For example, polyol (Y) may contain only a polyol (d) with three or more members, or it may contain and combine a polyol (d) with three or more members and a diol (e).

[0082] (Polyol(d))

[0083] The polyol (Y) preferably contains polyol (d) with three or more hydroxyl groups. The polyol (d) is a polyol having three or more hydroxyl groups in one molecule. By using polyol (d) with three or more hydroxyl groups, the amount of rosin (a) introduced into the molecule of the rosin-modified unsaturated polyester can be increased, thereby enabling the rosin-modified unsaturated polyester to exhibit higher surface hardness and water resistance after curing.

[0084] Examples of polyols with three or more members (d) include: glycerol, 1,1,1-trimethylolethane, 1,1,1-trimethylolpropane (also simply called "trimethylolpropane"), trioxyisobutane, 1,2,3-butanetriol, 1,2,3-pentanetriol, 2,3,4-pentanetriol, 1,2,5-hexanetriol, etc.; pentaerythritol, etc.; dipentaerythritol, glucose, sucrose, sorbitol, etc., etc.; and their epoxide adducts (ethylene oxide, propylene oxide, etc.). It should be noted that polyols with three or more members (d) can be used alone or in combination of two or more.

[0085] From a reactivity point of view, polyols with three or more nucleotides (d) are preferably ternary or quaternary polyols. As ternary polyols, glycerol and trimethylolpropane are preferred, with glycerol being more preferred. As quaternary polyols, pentaerythritol is preferred.

[0086] The polyol (d) with 3 or more nucleotides preferably includes a polyol with 3 nucleotides, and more preferably includes a polyol with 3 nucleotides and a polyol with 4 nucleotides. This increases the amount of hydroxyl groups available for the esterification reaction and increases the amount of rosin (a) introduced into the structure of the rosin-modified unsaturated polyester.

[0087] By including both trivalent and quadrivalent polyols in the polyol (d) with three or more components, the proportion of rosin (a) can be preferably set to a high value of 50 parts by mass or more relative to 100 parts by mass of the total amount of carboxylic acid (X) and polyol (Y). As a result, the rosin-modified unsaturated polyester exhibits higher surface hardness and water resistance after curing.

[0088] Relative to the total amount of carboxylic acids (X) and polyols (Y) 100 parts by mass, the proportion of polyols (d) with three or more components in the raw material compound is preferably 5 parts by mass or more, more preferably 10 parts by mass or more. Relative to the total amount of carboxylic acids (X) and polyols (Y) 100 parts by mass, the proportion of polyols (d) with three or more components in the raw material compound is preferably 30 parts by mass or less, more preferably 20 parts by mass or less.

[0089] (diol(e))

[0090] The polyol (Y) preferably further comprises a diol (e). The diol (e) is a polyol having two hydroxyl groups in one molecule (a di-membered polyol). By using the diol (e), the carboxyl groups of the carboxylic acid (X) can be fully esterified, reducing the amount of excess carboxyl groups not supplied for the esterification reaction, and thus reducing the methanol tolerance of the rosin-modified unsaturated polyester.

[0091] Examples of diols (e) include: methylene glycol, ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,10-decanediol, 4,4'-dihydroxyphenylpropane, 4,4'-dihydroxymethylmethane, diethylene glycol, triethylene glycol, polyethylene glycol (PEG), dipropylene glycol, polytetramethylene glycol (PTMG), polypropylene glycol (PPG), 1,4-cyclohexanediol, 1,4-cyclohexanediol, bisphenol A, bisphenol F, and their alkyl oxide (ethylene oxide, propylene oxide, etc.) adducts. A diol (e) can be used alone or in combination of two or more.

[0092] The number of carbon atoms in the diol (e) is preferably 6 or less, more preferably 4 or less. The number of carbon atoms in the diol (e) is preferably 1 or more, more preferably 2 or more. A lower number of carbon atoms in the diol (e) can increase the softening point of the rosin-modified unsaturated polyester, thereby allowing the rosin-modified unsaturated polyester to exhibit higher surface hardness after curing.

[0093] The preferred diols (e) are 1,2-propanediol, 1,3-propanediol, 1,6-hexanediol and neopentyl glycol, and more preferably 1,3-propanediol and neopentyl glycol.

[0094] The polyol (Y) preferably contains polyol (d) with three or more nucleotides, and more preferably contains polyol (d) with three or more nucleotides and diol (e). As a result, the rosin-modified unsaturated polyester exhibits higher surface hardness and water resistance after curing.

[0095] When the polyol (Y) contains a polyol (d) with three or more hydroxyl groups and a diol (e), the content of the polyol (d) with three or more hydroxyl groups in the polyol (Y) is preferably 40 mol% or more, more preferably 50 mol% or more, and even more preferably 55 mol% or more. When the polyol (Y) contains a polyol (d) with three or more hydroxyl groups and a diol (e), the content of the polyol (d) with three or more hydroxyl groups in the polyol (Y) is preferably 70 mol% or less, and even more preferably 65 mol% or less. By setting the content of the polyol (d) with three or more hydroxyl groups to 40 mol% or more, the amount of rosin-like compounds (a) introduced into the molecules of the rosin-modified unsaturated polyester can be increased, thereby enabling the rosin-modified unsaturated polyester to exhibit higher surface hardness and water resistance after curing. By setting the content of the polyol (d) with three or more hydroxyl groups to 70 mol% or less, the amount of excess hydroxyl groups not supplied for the esterification reaction can be reduced, thereby decreasing methanol resistance.

[0096] Relative to 100 parts by mass of the total amount of carboxylic acid (X) and polyol (Y), the content of polyol (Y) in the raw material compound is preferably 10 parts by mass or more, more preferably 15 parts by mass or more. Relative to 100 parts by mass of the total amount of carboxylic acid (X) and polyol (Y), the content of polyol (Y) in the raw material compound is preferably 60 parts by mass or less, more preferably 35 parts by mass or less. By setting the content of polyol (Y) to 10 parts by mass or more, the carboxyl groups of the carboxylic acid (X) can be fully esterified, thereby reducing the methanol tolerance of the rosin-modified unsaturated polyester. By setting the content of polyol (Y) to 60 parts by mass or less, the amount of excess hydroxyl groups not supplied for the esterification reaction can be reduced, thereby reducing methanol tolerance.

[0097] There are no particular limitations on the molecular structure of rosin-modified unsaturated polyesters. For example, when the polyol (Y) contains a polyol (d) with three or more hydroxyl groups and a diol (e), the rosin-modified unsaturated polyester is preferably a condensation polymer obtained by esterifying an α,β-unsaturated dicarboxylic acid (b) and a diol (e) with an esterified product containing hydroxyl groups (I), which is a product of esterification of rosin (a) and a polyol (d) with three or more hydroxyl groups. In such a rosin-modified unsaturated polyester, the esterification reaction of each raw material compound is fully carried out, which can reduce the amount of unreacted carboxyl and hydroxyl groups contained in the rosin-modified unsaturated polyester. As a result, the methanol tolerance of the rosin-modified unsaturated polyester can be reduced. That is, the methanol tolerance of the rosin-modified unsaturated polyester at 25°C can preferably be set to 100g or less.

[0098] When the carboxylic acid (X) further includes other carboxylic acids (c), the rosin-modified unsaturated polyester is preferably a condensation polymer obtained by esterifying α,β-unsaturated dicarboxylic acids (b) and diols (e) with a hydroxyl-containing ester (I) that is the product of an esterification reaction of rosin (a), other carboxylic acids (c), and polyols with three or more nucleotides (d). In such a rosin-modified unsaturated polyester, the esterification reaction of each raw material compound is fully carried out, thereby reducing the methanol tolerance of the rosin-modified unsaturated polyester.

[0099] In the raw material compound, the ratio of the total molar number of hydroxyl groups in the polyol (Y) to the total molar number of carboxyl groups in the carboxylic acid (X) [total molar number of hydroxyl groups in polyol (Y) / total molar number of carboxyl groups in carboxylic acid (X)] is preferably 0.95 or more, more preferably 1.00 or more. In the raw material compound, the ratio of the total molar number of hydroxyl groups in the polyol (Y) to the total molar number of carboxyl groups in the carboxylic acid (X) [total molar number of hydroxyl groups in polyol (Y) / total molar number of carboxyl groups in carboxylic acid (X)] is preferably 1.30 or less, more preferably 1.15 or less. By setting the above ratio within the above range, the hydroxyl groups of the polyol (Y) are sufficiently esterified by the carboxyl groups of the carboxylic acid (X) containing rosin (a), thereby increasing the degree of esterification. As a result, the methanol tolerance of the rosin-modified unsaturated polyester can be easily adjusted to 100 g or less. Consequently, the surface hardness and water resistance of the cured product made using the rosin-modified unsaturated polyester can be improved. In addition, it can reduce the azeotropic reaction of polyol (Y) due to dehydration during the esterification reaction of rosin-modified unsaturated polyester.

[0100] It should be noted that, as mentioned above, carboxylic acids (X) include various carboxylic acids such as rosin (a) and α,β-unsaturated dicarboxylic acids (b). Therefore, the total molar number of carboxyl groups in carboxylic acids (X) can be calculated as follows. First, for each carboxylic acid (X), the molar number of carboxyl groups (M) is calculated by multiplying the molar number of carboxylic acids (X) contained in the starting compound by the number of carboxyl groups possessed by 1 molecule of that carboxylic acid (X). COOH Next, the number of moles of carboxyl groups (M) calculated for each carboxylic acid (X) will be... COOH The totals are calculated and the resulting value is taken as the "total number of carboxyl groups in carboxylic acids (X)".

[0101] It should be noted that in "total molar number of carboxyl groups in carboxylic acids (X)," the molar number of carboxyl groups (M) for rosin (a) is not specified. COOHThe calculation is as follows. First, the acid value of the rosin (A) contained in the raw material compound is determined, and the amount of carboxyl groups per unit mass of rosin (A) is calculated. Based on this amount of carboxyl groups, the average molecular weight of rosin (A) is determined. Then, by using the obtained average molecular weight and the content of rosin (A) contained in the raw material compound, the molar number (M) of carboxyl groups in rosin (a) is calculated. COOH ).

[0102] It should be noted that the acid value of rosin (A) can be determined according to JIS K5601-2-1 (1999).

[0103] Furthermore, the total number of moles of hydroxyl groups in the polyol (Y) can be calculated as follows. The polyol (Y) sometimes contains multiple polyols, such as polyols with three or more hydroxyl groups (d) and diols (e). Therefore, firstly, for each polyol (Y), the number of moles of hydroxyl groups (M) is calculated by multiplying the number of moles of polyol (Y) contained in the starting compound by the number of hydroxyl groups possessed by one molecule of that polyol (Y). OH Next, the number of moles of hydroxyl groups (M) for each polyol (Y) will be calculated. OH The totals are calculated and the resulting value is taken as the "total number of moles of hydroxyl groups in polyol (Y)".

[0104] The raw material compounds constituting rosin-modified unsaturated polyesters may further include monohydric alcohols. A monohydric alcohol is a compound having one hydroxyl group in one molecule. Examples of monohydric alcohols include methanol, ethanol, propanol, and isopropanol. Monohydric alcohols can be used alone or in combination of two or more.

[0105] The weight-average molecular weight of the rosin-modified unsaturated polyester is preferably 3000 or more, more preferably 4000 or more. The weight-average molecular weight of the rosin-modified unsaturated polyester is preferably 50000 or less, more preferably 20000 or less. When the weight-average molecular weight of the rosin-modified unsaturated polyester is 3000 or more, the water resistance and surface hardness of the cured product made from the rosin-modified unsaturated polyester can be improved. When the weight-average molecular weight of the rosin-modified unsaturated polyester is 50000 or less, gelation and excessive molecular weight increase of the rosin-modified unsaturated polyester are reduced, and the solubility of the rosin-modified unsaturated polyester for the free radical polymerizable monomers described later can be improved.

[0106] Furthermore, by setting the weight-average molecular weight of the rosin-modified unsaturated polyester to 20,000 or less, the heating temperature at which the rosin-modified unsaturated polyester is dissolved in the free radical polymerizable monomer can be reduced when manufacturing the rosin-modified unsaturated polyester composition. This allows for the appropriate use of free radical polymerizable monomers with lower boiling points, such as styrene.

[0107] The weight-average molecular weight of rosin-modified unsaturated polyester is the value obtained by converting the molecular weight determined by gel permeation chromatography (GPC) to polystyrene. For example, it can be determined under the following conditions: Rosin-modified unsaturated polyester is dissolved in tetrahydrofuran to obtain a test sample with a concentration of 0.5% by mass. This test sample can be used to determine the weight-average molecular weight of the rosin-modified unsaturated polyester using gel permeation chromatography (GPC) equipped with a refractive index detector (RID) under the following apparatus and conditions.

[0108] Measuring apparatus: Showa Denko Co., Ltd. "Shodex GPC-101"

[0109] Pillars: 2 x "KF-802" + "KF-806L" manufactured by Showa Denko Co., Ltd.

[0110] Detector: Shodex RI-71 (Differential Refractive Index Detector)

[0111] Data processing: "480IIXP"

[0112] Standard polystyrene (manufactured by Showa Denko Co., Ltd., "S-0.5", "S-1.0", "S-1.2", "S-1.9", "S-2.9", "S-3.1", "S-4.4", "S-5.1", "S-7.2", "S-19.6", "S-49.2", "S-114", "S-257", "S-778", "S-1320", "S-7450")

[0113] Column temperature: 40℃

[0114] Solvent: Tetrahydrofuran

[0115] Flow rate: 1.0 mL / min

[0116] Sample concentration: 0.5% by mass

[0117] Injection volume: 100μm

[0118] (Manufacturing method of rosin-modified unsaturated polyester)

[0119] Rosin-modified unsaturated polyester can be manufactured by polycondensation of a raw material compound containing a carboxylic acid (X) and a polyol (Y), wherein the carboxylic acid (X) includes rosin (a) and α,β-unsaturated dicarboxylic acids (b). Rosin-modified unsaturated polyester can be obtained by polycondensation (esterification) of the carboxylic acid (X) and the polyol (Y) accompanied by dehydration.

[0120] The polycondensation of the starting material compounds can be carried out using known methods. For example, one method involves mixing the starting material compounds in the presence of a solvent added as needed and heating them to induce a reaction.

[0121] There are no particular limitations on the solvents used. Examples include: petroleum hydrocarbon solvents such as hexane and mineral spirits; aromatic hydrocarbon solvents such as benzene, toluene, and xylene; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, diisobutyl ketone, and cyclohexanone; ester solvents such as methyl acetate, ethyl acetate, butyl acetate, γ-butyrolactone, and propylene glycol monomethyl ether acetate; and nonprotic polar solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, N-methylpyrrolidone, and pyridine. A single solvent can be used, or two or more can be used in combination. It should be noted that there are no particular restrictions on the mixing ratio of solvents; it can be appropriately set according to the purpose and application.

[0122] For example, an ester reaction can be initiated by heating the starting compound in the presence of an azeotropic solvent capable of azeotropically reacting with water (e.g., xylene, toluene, or other azeotropic dehydrating agents), and the water produced by the reaction can be distilled off. Furthermore, the solvent can be removed as needed after the reaction is complete. Alternatively, an ester reaction can also be initiated, for example, by heating the starting compound under solvent-free conditions, and the water produced can be distilled off using known methods.

[0123] Polycondensation of the raw material compound is preferably carried out in the presence of an esterification catalyst. There are no particular limitations on the esterification catalyst; examples include: organic sulfonic acids such as benzenesulfonic acid, p-toluenesulfonic acid, p-dodecylbenzenesulfonic acid, methanesulfonic acid, and ethanesulfonic acid; inorganic acids such as sulfuric acid and hydrochloric acid; metal catalysts such as tetrabutyl zirconate, tetraisopropyl titanate, tetraisobutyl titanate, alumina, titanium dioxide, magnesium oxide, magnesium hydroxide, magnesium acetate, calcium oxide, calcium hydroxide, calcium acetate, zinc oxide, and zinc acetate; and trifluoromethanesulfonic acid and trifluoromethylacetic acid. One esterification catalyst can be used alone, or two or more can be used in combination. There are no particular limitations on the proportion of esterification catalyst added; it is appropriately set according to the purpose and application.

[0124] The polycondensation of the raw material compound is preferably carried out under atmospheric pressure and in an inert gas atmosphere. During the polycondensation of the raw material compound, the heating temperature is preferably 150–280°C, more preferably 200–250°C. Furthermore, the heating time is preferably 4–20 hours, more preferably 6–15 hours.

[0125] In the polycondensation of the starting materials, there are no particular restrictions on the order in which the starting materials react, i.e., the order in which they are mixed. All the starting materials can be mixed simultaneously for polycondensation, or they can be mixed in any order for polycondensation. For example, if the carboxylic acid (X) includes rosin (a) and α,β-unsaturated dicarboxylic acids (b), and the alcohol (Y) includes polyols with three or more nucleotides (d) and diols (e), the starting materials can be polycondensed in any order, but preferably in the order shown below.

[0126] That is, the preferred method for manufacturing rosin-modified unsaturated polyester includes:

[0127] The first esterification step involves heating rosin (a) and a polyol with three or more hydroxyl groups (d) at a temperature of 230°C or higher to induce an esterification reaction, yielding an esterified compound (I) with hydroxyl groups; and

[0128] The second esterification step, after the first esterification step, involves heating the esterified compound (I), α,β-unsaturated dicarboxylic acids (b), and diol (e) at a temperature above 180°C and below 230°C to carry out an esterification reaction, thereby obtaining rosin-modified unsaturated polyester.

[0129] In the above method, after the esterification reaction of rosin (a) and polyols with three or more nucleotides (d) is carried out in the first esterification step, the esterification reaction of α,β-unsaturated dicarboxylic acids (b) is carried out in the second esterification step. Therefore, for example, even when the rosin (a) contains a resin acid with conjugated double bonds, the addition of α,β-unsaturated dicarboxylic acids (b) to the resin acid via the Diels-Alder reaction can be reduced, and the unsaturated bonds from the α,β-unsaturated dicarboxylic acids (b) can be fully introduced into the rosin-modified unsaturated polyester.

[0130] Furthermore, in the above method, in the first esterification step, the esterification reaction of rosin (a) and polyols with three or more nucleotides (d) can be carried out first before the reaction of α,β-unsaturated dicarboxylic acids (b) and diols (e), thereby increasing the heating temperature during the esterification reaction. This allows for a more thorough esterification reaction of rosin (a) and polyols with three or more nucleotides (d), and even with a high proportion of rosin (a), the methanol tolerance of the final rosin-modified unsaturated polyester can be reduced.

[0131] The heating temperature in the first esterification step is preferably 230°C or higher, more preferably 240°C or higher. The heating temperature in the first esterification step is preferably 280°C or lower, more preferably 250°C or lower.

[0132] When the carboxylic acid (X) further includes other carboxylic acids (c), it is preferable to carry out the esterification reaction of the other carboxylic acids (c) in the first esterification step. That is, it is preferable to carry out the esterification reaction of rosin (a) and other carboxylic acids (c) with polyols (d) with three or more nucleotides in the first esterification step.

[0133] In the first esterification step, rosin (a) and other carboxylic acids (c) added as needed are esterified with an excess of polyols with three or more hydroxyl groups (d) to obtain an esterified compound (I) with hydroxyl groups. In order to ensure that the esterification reaction is carried out sufficiently, it is preferable to set the acid value of the esterified compound (I) with hydroxyl groups obtained in the first esterification step to 10 mg KOH / g or less.

[0134] In the second esterification step, the esterified product (I) obtained in the first esterification step, α,β-unsaturated dicarboxylic acids (b) and diol (e) are heated at a lower heating temperature to further carry out the esterification reaction, thereby obtaining rosin-modified unsaturated polyester.

[0135] The heating temperature in the second esterification step is preferably 180°C or higher, more preferably 190°C or higher, and even more preferably 200°C or higher. The heating temperature in the second esterification step is preferably below 230°C, more preferably below 220°C, and even more preferably below 210°C. By conducting the esterification reaction at such a lower heating temperature, the esterification reaction between the hydroxyl-containing ester (I) obtained in the first esterification step and the α,β-unsaturated dicarboxylic acid (b) and diol (e) can proceed sufficiently, thereby reducing the methanol tolerance of the final rosin-modified unsaturated polyester. Furthermore, by setting the reaction temperature of the second esterification step within the above-mentioned range, even when unmodified rosin is used as the rosin (a), the unsaturated bonds from the α,β-unsaturated dicarboxylic acid (b) can remain in the rosin-modified unsaturated polyester at a high residual rate. Therefore, the final rosin-modified unsaturated polyester can more reliably copolymerize with free radical polymerizable monomers.

[0136] In the second esterification step, it is preferable to cool the esterified compound (I) obtained in the first esterification step to below 180°C, particularly to 150-180°C, and then heat the esterified compound (I) with the α,β-unsaturated dicarboxylic acid (b) and the diol (e) at the above-mentioned heating temperature to carry out the esterification reaction.

[0137] In the second esterification step, the esterification reaction of the esterified product (I), α,β-unsaturated dicarboxylic acid (b), and diol (e) is preferably carried out in the presence of a polymerization inhibitor.

[0138] Rosin-based products (a) sometimes contain rosin metal salts as unavoidable impurities. The metal atoms contained in such rosin metal salts can act as catalysts for the esterification reaction in the first esterification step. On the other hand, in the second esterification step, these metal atoms sometimes act as polymerization catalysts that promote the polymerization of α,β-unsaturated dicarboxylic acids (b) with each other. As a result, rosin-modified unsaturated polyesters sometimes become high in molecular weight and gel. Therefore, by using a polymerization inhibitor to suppress the polymerization of α,β-unsaturated dicarboxylic acids (b) with each other in the second esterification step, gelation of rosin-modified unsaturated polyesters can be reduced.

[0139] Metal atoms that can be classified as rosin metal salts include, for example, at least one of iron, copper, zinc, aluminum, and magnesium atoms. The content of rosin metal salts in rosin type (a) is extremely small.

[0140] Examples of polymerization inhibitors include: phenolic inhibitors such as (alkyl)phenol, p-methoxyphenol, o-isopropylphenol, catechol, resorcinol, tert-butylcatechol, pyrogallol, dibutylcresol, and guaiacol; nitroso-based inhibitors such as nitrosobenzene, N-nitrosophenylhydroxylamine aluminum, tri-p-nitrosophenylmethane, picric acid, copper-iron reagent, butyraldehyde oxime, methyl ethyl ketone oxime, and cyclohexanone oxime; quinone-based inhibitors such as hydroquinone, tert-butylhydroquinone (TBHQ), p-benzoquinone, and 2,5-di-tert-butyl-p-benzoquinone; and piperidine-based inhibitors such as phenothiazine. Preferably, nitroso-based and quinone-based inhibitors are used, more preferably N-nitrosophenylhydroxylamine aluminum and tert-butylhydroquinone. Inhibitors can be used alone or in combination of two or more.

[0141] The amount of polymerization inhibitor is preferably 0.001 to 5 parts by mass relative to the total amount of carboxylic acids (X) and polyols (Y) of 100 parts by mass, and more preferably 0.01 to 1 part by mass. By setting the amount of polymerization inhibitor within the above range, the polymerization of α,β-unsaturated dicarboxylic acids (b) in the second esterification step can be sufficiently suppressed.

[0142] The acid value of the rosin-modified unsaturated polyester obtained in the second esterification step is preferably set to 30 mg KOH / g or less, and more preferably 20 mg KOH / g or less. Therefore, by ensuring a sufficient esterification reaction in the second esterification step, the methanol tolerance of the final rosin-modified unsaturated polyester can be reduced.

[0143] It should be noted that the acid value of the esterified product (I) obtained in the first step and the acid value of the rosin-modified unsaturated polyester obtained in the second esterification step can be determined according to JIS K5601-2-1 (1999). In addition, the hydroxyl value of the rosin-modified unsaturated polyester can be determined according to JIS K 0070 (1992).

[0144] When a polymerization inhibitor is used in the second esterification step, the rosin-modified unsaturated polyester obtained by the method of the present invention described above is obtained in the form of a mixture with the polymerization inhibitor. That is, when a polymerization inhibitor is used in the second esterification step, a composition containing rosin-modified unsaturated polyester and a polymerization inhibitor can be obtained. Then, by adding the free radical polymerizable monomers described later, as well as polymerization initiators and curing accelerators added as needed, a rosin-modified unsaturated polyester composition can be obtained. In addition, if necessary, a polymerization inhibitor can be further added to the rosin-modified unsaturated polyester composition.

[0145] <Rosin-modified unsaturated polyester composition>

[0146] The aforementioned rosin-modified unsaturated polyester can be suitably used as a rosin-modified unsaturated polyester composition comprising therein. The rosin-modified unsaturated polyester composition comprises a rosin-modified unsaturated polyester and a free-radical polymerizable monomer. By using the rosin-modified unsaturated polyester of the present invention, the rosin-modified unsaturated polyester composition can form a cured product with excellent surface hardness and water resistance. This cured product can be molded into a desired shape for suitable use.

[0147] Rosin-modified unsaturated polyesters contain unsaturated bonds in their molecules. Examples of unsaturated bonds include carbon-carbon double bonds and carbon-carbon triple bonds. Among these, carbon-carbon double bonds are preferred.

[0148] Examples of free radical polymerizable monomers include: vinyl compounds such as styrene, chlorostyrene, dichlorostyrene, tert-butylstyrene, vinylnaphthalene, ethyl vinyl ether, methyl vinyl ketone, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, acrylonitrile, and methacrylonitrile; allyl compounds such as diallyl phthalate, diallyl terephthalate, diallyl succinate, and triallyl cyanurate, and their oligomers. Styrene, methylstyrene, and diallyl phthalate are preferred, and styrene and methylstyrene are more preferred. These free radical polymerizable monomers can readily copolymerize with rosin-modified unsaturated polyesters, thereby enabling more reliable curing of the rosin-modified unsaturated polyester composition. As a result, the surface hardness and water resistance of the cured rosin-modified unsaturated polyester composition can be further improved. It should be noted that the free radical polymerizable monomers can be used alone or in combination of two or more.

[0149] The content of free radical polymerizable monomers can be adjusted appropriately according to the viscosity and application of the rosin-modified unsaturated polyester composition. In the rosin-modified unsaturated polyester composition, the content of free radical polymerizable monomers is preferably 10 to 200 parts by weight relative to 100 parts by weight of rosin-modified unsaturated polyester, more preferably 30 to 150 parts by weight.

[0150] The viscosity of the rosin-modified unsaturated polyester composition at 25°C is preferably 10~10000 mPa·s, more preferably 50~5000 mPa·s.

[0151] The viscosity of the rosin-modified unsaturated polyester composition at 25°C is the viscosity measured using a rheometer (e.g., Thermo Haake, trade name "HAAKE RheoStress 600") at a temperature of 25°C and a frequency of 1.0 Hz.

[0152] The rosin-modified unsaturated polyester composition preferably contains a polymerization initiator. Thermal polymerization initiators can be suitably used as polymerization initiators. Examples include organic peroxides such as methyl ethyl ketone peroxide, acetylacetone peroxide, tert-butyl peroxide, benzoyl peroxide, dicumyl peroxide, and cumyl hydroperoxide. In the rosin-modified unsaturated polyester composition, the proportion of the polymerization initiator is preferably 0.1 to 5 parts by mass relative to 100 parts by mass of the total amount of rosin-modified unsaturated polyester and free radical polymerizable monomers.

[0153] The rosin-modified unsaturated polyester composition preferably includes a curing accelerator. Examples of curing accelerators include cobalt naphthenate, cobalt isooctanoate, N,N-dimethylaniline, N,N-diethylaniline, N,N-dimethyl-p-toluidine, acetylacetone, and ethyl acetoacetate. In the rosin-modified unsaturated polyester composition, the curing accelerator is preferably present in a proportion of 0.05 to 5 parts by mass relative to 100 parts by mass of the total amount of rosin-modified unsaturated polyester and free radical polymerizable monomers.

[0154] The rosin-modified unsaturated polyester composition preferably contains a polymerization inhibitor. The polymerization inhibitor reduces unnecessary polymerization of the rosin-modified unsaturated polyester and free radical polymerizable monomers during storage, thereby improving storage stability.

[0155] As a polymerization inhibitor, an example is the same polymerization inhibitor used in the second esterification step of the method of the present invention described above. The preferred content of the polymerization inhibitor is 0.05 to 5 parts by mass relative to 100 parts by mass of the total amount of rosin-modified unsaturated polyester and free radical polymerizable monomers.

[0156] There are no particular limitations on the method for manufacturing rosin-modified unsaturated polyester compositions. For example, a rosin-modified unsaturated polyester composition can be obtained by dissolving rosin-modified unsaturated polyester in a free radical polymerizable monomer. Polymerization initiators, curing accelerators, and polymerization inhibitors can be added as needed.

[0157] The curing of the rosin-modified unsaturated polyester composition can be achieved by copolymerizing the rosin-modified unsaturated polyester with a free-radical polymerizable monomer. The polymerization temperature of the rosin-modified unsaturated polyester and the free-radical polymerizable monomer can be adjusted according to the type of polymerization initiator, preferably 20-150°C, more preferably 25-120°C. Furthermore, the polymerization time is preferably 2-30 hours, more preferably 3-10 hours. The polymerization reaction is preferably carried out in an inert gas atmosphere such as nitrogen.

[0158] By using rosin-modified unsaturated polyester, rosin-modified unsaturated polyester compositions can form cured products (molded bodies) with high surface hardness. Such cured products exhibit excellent scratch resistance and maintain a beautiful appearance for a long time. When a thermal polymerization initiator is included in the rosin-modified unsaturated polyester composition, the composition can be fully cured to the interior. Therefore, the cured product exhibits even better scratch resistance.

[0159] Furthermore, by using rosin-modified unsaturated polyester, rosin-modified unsaturated polyester compositions can form cured products (molded articles) with high water resistance. Such cured products can reduce the decrease in mechanical strength caused by contact with water. Therefore, even when the cured product is in contact with water such as rainwater and moisture for a long time, it can maintain high mechanical strength.

[0160] As described above, rosin-modified unsaturated polyester compositions can form cured products with both high surface hardness and high water resistance. Therefore, rosin-modified unsaturated polyester compositions can be used for a variety of applications. There are no particular limitations on the applications of rosin-modified unsaturated polyester compositions. For example, rosin-modified unsaturated polyester compositions can be used to form molded articles that are cured into desired shapes.

[0161] Furthermore, rosin-modified unsaturated polyester compositions can also be suitably used as adhesives for bonding materials together. This allows for the formation of molded bodies where the materials are bonded together by a cured rosin-modified unsaturated polyester composition. When the rosin-modified unsaturated polyester composition is used in this manner, molded bodies with excellent surface hardness and water resistance can be obtained. Examples of materials that can be bonded include particles such as inorganic particles and synthetic resin particles, as well as fibers such as reinforcing fibers.

[0162] Rosin-modified unsaturated polyester compositions can be used as fiber-reinforced plastics (FRP).

[0163] Fiber-reinforced plastics comprise a cured rosin-modified unsaturated polyester composition and reinforcing fibers. The cured rosin-modified unsaturated polyester composition acts as an adhesive to integrate the reinforcing fibers. That is, in fiber-reinforced plastics, the cured rosin-modified unsaturated polyester composition functions as an adhesive (bundling agent) to bond the reinforcing fibers together. By using the cured rosin-modified unsaturated polyester composition in this way, fiber-reinforced plastics with high surface hardness and water resistance can be provided.

[0164] Examples of reinforcing fibers include: inorganic fibers such as glass fiber, carbon fiber, metal fiber, and ceramic fiber; organic fibers such as polyvinyl alcohol fiber, polyester fiber, polyamide fiber, fluoropolymer fiber, and phenolic fiber; and natural fibers such as hemp and kenaf. Inorganic fibers are preferred, carbon fiber and glass fiber are more preferred, and glass fiber is even more preferred. A single reinforcing fiber may be used alone, or two or more may be used in combination. The reinforcing fiber is preferably used as a reinforcing fiber substrate processed into a desired shape.

[0165] Known methods can be used as a method for manufacturing fiber-reinforced plastics. For example, a prepreg is obtained by impregnating reinforcing fibers with a rosin-modified unsaturated polyester composition, followed by curing the rosin-modified unsaturated polyester composition, thereby obtaining a fiber-reinforced plastic. The applications of fiber-reinforced plastics are not particularly limited; examples include ship hulls, bathtubs, building materials, and industrial equipment.

[0166] Example

[0167] The present invention will be described in more detail below using examples, but the present invention is not limited thereto.

[0168] [Examples 1-5, Comparative Examples 1 and 2]

[0169] (Synthesis of rosin-modified unsaturated polyester)

[0170] In a four-necked flask equipped with a thermometer, stirrer, inert gas inlet, and reflux cooler, disproportionated rosin (trade name "G-100F" manufactured by Harima Chemicals), adipic acid, tetrahydrophthalic anhydride, isophthalic acid, stearic acid, benzoic acid, glycerol, and pentaerythritol, as raw material compounds, were added according to the proportions shown in Table 1. The mixture was heated at 250°C to carry out a dehydration condensation reaction of the raw material compounds, thereby forming an ester with hydroxyl groups (I) (first esterification step). The dehydration condensation reaction continued until the acid value of the final ester (I) reached below 10 mg KOH / g.

[0171] Next, the four-necked flask was cooled to 180°C, and 1,3-propanediol, 1,6-hexanediol, neopentyl glycol, maleic anhydride, and N-nitrosophenylhydroxylamine aluminum (manufactured by FUJIFILM, trade name "Q1305") and tert-butylhydroquinone (TBHQ) as polymerization inhibitors were added to the flask in the proportions shown in Table 1. The mixture was heated to 200°C to carry out a dehydration condensation reaction of the esterified compound (I) and the raw material compounds, thereby forming rosin-modified unsaturated polyester (second esterification step). Thus, a mixture containing rosin-modified unsaturated polyester and polymerization inhibitors was obtained. The dehydration condensation reaction continued until the acid value of the final rosin-modified unsaturated polyester reached below 20 mg KOH / g.

[0172] (Preparation of rosin-modified unsaturated polyester composition)

[0173] A rosin-modified unsaturated polyester composition was obtained by mixing 60.06 parts by weight of the above mixture (60 parts by weight of rosin-modified unsaturated polyester and 0.06 parts by weight of polymerization inhibitor), 40 parts by weight of 4-methylstyrene, 1 part by weight of cobalt naphthenate, and 2 parts by weight of a solution containing 55% by weight of methyl ethyl ketone peroxide (MEKP). In the rosin-modified unsaturated polyester composition, the rosin-modified unsaturated polyester is dissolved in 4-methylstyrene.

[0174] It should be noted that the disproportionated rosin used in the first esterification process contains trace amounts of rosin metal salts as unavoidable impurities. The metal atoms contained in the rosin metal salts are at least one of iron, copper, zinc, aluminum, and magnesium atoms.

[0175] The ratio of the total number of hydroxyl groups in the polyol (Y) of all raw material compounds used in the first and second esterification processes to the total number of carboxyl groups in the carboxylic acid (X) [total number of hydroxyl groups in polyol (Y) / total number of carboxyl groups in carboxylic acid (X)] is shown in the "Ratio [total number of hydroxyl groups / total number of carboxyl groups]" column of Table 1.

[0176] [evaluate]

[0177] The rosin-modified unsaturated polyesters and rosin-modified unsaturated polyester compositions obtained in the Examples and Comparative Examples were evaluated as follows.

[0178] For rosin-modified unsaturated polyesters, the methanol tolerance, softening point, acid value, and hydroxyl value at 25°C were determined according to the steps described above. The results are shown in Table 1.

[0179] (Ease of synthesis)

[0180] For rosin-modified unsaturated polyesters, the weight-average molecular weight was determined according to the above steps, and the evaluation was based on the following criteria. The evaluation results are shown in Table 1.

[0181] <Evaluation Criteria>

[0182] A: The weight average molecular weight of rosin-modified unsaturated polyester is below 20,000.

[0183] B: Rosin-modified unsaturated polyesters with a weight-average molecular weight greater than 20,000 and less than 50,000 can be considered to have no problems in practical use.

[0184] X: The weight-average molecular weight of rosin-modified unsaturated polyester is greater than 50,000.

[0185] It should be noted that, considering factors such as solubility for free radical polymerizable monomers, the weight-average molecular weight of rosin-modified unsaturated polyesters is preferably low, for example, preferably 50,000 or less, and particularly preferably 20,000 or less. On the other hand, it is sometimes difficult to adjust the weight-average molecular weight during the synthesis of rosin-modified unsaturated polyesters. Specifically, as the reaction with the raw material compound begins, the molecular weight of the reaction products of the raw material compound gradually increases, but in the later stages of the reaction, the molecular weight of the reaction products of the raw material compound has increased significantly. The reaction products react with each other, leading to a sharp increase in molecular weight and causing gelation, sometimes making it difficult to obtain rosin-modified unsaturated polyesters with low weight-average molecular weight. However, according to the method of the present invention, the above-mentioned sharp increase in molecular weight and the occurrence of gelation can be reduced, and rosin-modified unsaturated polyesters with low weight-average molecular weight can be easily manufactured. Therefore, in the case of manufacturing large quantities of rosin-modified unsaturated polyesters in factories, etc., the method of the present invention does not require strict control of reaction conditions such as the reaction time of the raw material compound, which can reduce the burden of controlling reaction conditions and allow for the reproducible manufacture of rosin-modified unsaturated polyesters with low weight-average molecular weight.

[0186] (Surface hardness)

[0187] The rosin-modified unsaturated polyester composition was poured into a plastic container on a cylinder with a diameter of 65 mm. After being placed at room temperature under a nitrogen atmosphere for 3 hours, it was further placed at 80°C under a nitrogen atmosphere for 2 hours to cure it. Thus, a cured product of the rosin-modified unsaturated polyester composition (thickness: 3 mm) was obtained.

[0188] The surface hardness of the cured material was evaluated using a Pendulum hardness tester (BYK Corporation, trade name "Pendulum Hardness tester") according to ASTM D4366 (2014). Specifically, when a pendulum was oscillating with a metal ball (5 nm in diameter) in contact with the cured material as the fulcrum, the time it took for the pendulum amplitude to decrease from 6° to 3° was measured, and this decrease time was evaluated according to the following evaluation criteria. The evaluation results are shown in Table 1. It should be noted that a longer decrease time indicates a higher surface hardness of the cured material. The preferred evaluation criterion is 3 or higher. Therefore, the cured material can be considered to be at a practically usable level.

[0189] <Evaluation Criteria>

[0190] 5: The decay time is more than 120 seconds.

[0191] 4: The decay time is more than 100 seconds and less than 120 seconds.

[0192] 3: The decay time is more than 80 seconds and less than 100 seconds.

[0193] 2: The decay time is more than 60 seconds and less than 80 seconds.

[0194] 1: The decay time is less than 60 seconds.

[0195] (Water resistance)

[0196] In the surface hardness evaluation, a cured product (thickness: 3 mm) of the rosin-modified unsaturated polyester composition was obtained using the same method as described above. The cured product was immersed in ion-exchanged water at 50°C for one month. The mass change rate of the cured product before and after immersion was calculated based on the following formula, and the evaluation was carried out according to the following criteria. The evaluation results are shown in Table 1. It should be noted that the following evaluation criterion is preferably 3 or higher. Therefore, the cured product can be considered to be at a level suitable for practical use.

[0197] The mass change rate of the cured product [%] = 100 × (W0 - W1) / W0

[0198] (W0 is the mass of the cured material before impregnation [g], and W1 is the mass of the cured material after impregnation [g].)

[0199] <Evaluation Criteria>

[0200] 5: The mass change rate of the solidified product is less than 0.2%.

[0201] 4: The mass change rate of the solidified material is greater than 0.2% and less than 0.4%.

[0202] 3: The mass change rate of the solidified material is greater than 0.4% and less than 0.6%.

[0203] 2: The mass change rate of the solidified material is greater than 0.6% and less than 0.8%.

[0204] 1: The mass change rate of the solidified material is greater than 0.8%.

[0205]

[0206] Industrial applicability

[0207] The rosin-modified unsaturated polyester and the rosin-modified unsaturated polyester composition comprising the present invention exhibit high surface hardness and water resistance after curing. Therefore, such rosin-modified unsaturated polyester compositions can be suitably used as molded articles for fiber-reinforced plastics and the like.

[0208] (Cross-reference to related applications)

[0209] This application claims priority based on Japanese Patent Application No. 2024-11972, filed on January 30, 2024, the entire disclosure of which is incorporated herein by reference.

Claims

1. A rosin-modified unsaturated polyester having a methanol tolerance of less than 100g at 25°C.

2. The rosin-modified unsaturated polyester according to claim 1 has a softening point of 60°C or higher.

3. The rosin-modified unsaturated polyester according to claim 1 is a condensation polymer of a raw material compound comprising a carboxylic acid (X) and a polyol (Y), wherein the carboxylic acid (X) comprises rosin (a) and α,β-unsaturated dicarboxylic acid (b).

4. The rosin-modified unsaturated polyester according to claim 3, wherein, Rosin class (a) includes at least one of disproportionated rosin and hydrogenated rosin.

5. The rosin-modified unsaturated polyester according to claim 3, wherein, Polyol (Y) contains polyols (d) with 3 or more members.

6. A rosin-modified unsaturated polyester composition comprising: The rosin-modified unsaturated polyester of claim 1, and Polymerization inhibitor.

7. A rosin-modified unsaturated polyester composition comprising: The rosin-modified unsaturated polyester of claim 1, and Free radical polymerizable monomers.

8. The rosin-modified unsaturated polyester composition according to claim 7, wherein, The free radical polymerizable monomers include at least one of styrene and methylstyrene.

9. A molded article comprising a cured product of the rosin-modified unsaturated polyester composition of claim 8.

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