Heat-curable resin, composition, uncured molded object, partly cured molded object, cured molded object, and method for producing heat-curable resin

Abstract

Provided are: a benzoxazine-based resin which, before curing, has excellent flexibility and / or which is excellent in terms of decomposition temperature and toughness before and after curing; and a method for producing the benzoxazine-based resin. The heat-curable resin according to one aspect of the present invention is a heat-curable resin having a main chain including a benzoxazine ring structure, the heat-curable resin having an aromatic group derived from a bifunctional phenol compound (A) and a linear alkylene group derived from an aliphatic diamine compound (B) and optionally having a (poly)oxyalkylene group derived from a (poly)oxyalkylenediamine compound (C).

Description

Thermosetting resin, composition, uncured molded body, partially cured molded body, cured molded body, and method for producing thermosetting resin

[0001] The present disclosure relates to a thermosetting resin having a benzoxazine ring structure in the main chain, and a method for producing the same.

[0002] It is known that benzoxazine compounds undergo ring-opening polymerization and reaction of the benzoxazine rings under heat or other conditions, resulting in curing without the generation of volatile matter. Therefore, thermosetting resins primarily composed of low-molecular-weight compounds or polymers having a benzoxazine structure have attracted attention because they offer various advantages, such as low dielectric constant and low cure shrinkage, in addition to the basic characteristics of thermosetting resins, such as heat resistance, water resistance, chemical resistance, mechanical strength, and long-term reliability. While low-molecular-weight compounds having a benzoxazine structure are easy to manufacture, they are characterized by poor handling, such as being brittle in the solid state before curing. Furthermore, polymers having a benzoxazine structure are characterized by good handleability in the solid state before curing, but are difficult to manufacture, and therefore are used in different ways depending on their properties.

[0003] Patent Document 1 discloses a method for producing a thermosetting resin having a dihydrobenzoxazine ring structure in the main chain by reacting a bifunctional phenol compound, an aliphatic diamine or an aromatic diamine, and an aldehyde compound.

[0004] Japanese Patent Application Publication No. 2008-291070

[0005] However, the conventional benzoxazine resins described above have room for further improvement in terms of realizing a benzoxazine thermosetting resin with excellent flexibility before curing, as well as in terms of decomposition temperature and toughness before and after curing.

[0006] One aspect of the present disclosure aims to provide a benzoxazine-based thermosetting resin that has excellent flexibility before curing, and a method for producing the same. Another aspect of the present disclosure aims to provide a benzoxazine-based resin that has excellent decomposition temperature and toughness before and after curing, and a method for producing the same.

[0007] In order to solve the above problems, a thermosetting resin according to one embodiment of the present disclosure has a benzoxazine ring structure represented by general formula (I) in its main chain.

[0008] [In the general formula (I), Ar １ and Ar ２ may be the same or different and represent a tetravalent aromatic group derived from the bifunctional phenol compound (A), n represents an integer of 0 or more, R １ represents a linear alkylene group having 8 to 12 carbon atoms derived from the aliphatic diamine compound (B) when n=0, and represents a linear alkylene group having 6 to 12 carbon atoms derived from the aliphatic diamine compound (B) when n=1 or more, and R ２ represents a (poly)oxyalkylene group derived from the (poly)oxyalkylenediamine compound (C); when n = 0, at least one of the two ends of the main chain is a group represented by the following general formula (II) derived from the monofunctional phenol compound (E), and the two ends may be the same or different; when n = 0, m represents an integer of 2 or more; and when n = 1 or more, m represents an integer of 1 or more; the repeating unit represented by m and the repeating unit represented by n are repeated randomly, repeated as blocks, or are in the form of an alternating copolymer.

[0009] [In general formula (II), X represents a hydrogen atom or an organic group having 1 to 20 carbon atoms, and 1 represents an integer of 0 to 3.] In order to solve the above-mentioned problems, a thermosetting resin according to one embodiment of the present disclosure is a thermosetting resin having a benzoxazine ring structure in its main chain, wherein an uncured molded body having a degree of cure of less than 1% obtained by molding the thermosetting resin, or a partially cured molded body having a degree of cure of 1 to 99% obtained by curing the thermosetting resin, has thermoplastic remoldability and toughness, wherein the thermoplastic remoldability refers to the property that the uncured molded body or the partially cured molded body, after being deformed into an arbitrary shape, returns to its pre-deformed shape by heating at 200°C or less, and wherein the toughness refers to the property that the uncured molded body or the partially cured molded body does not break or crack before or after the heating, and wherein the remoldability and toughness are maintained even when the deformation and the heating are performed one or more times, and the thermosetting resin has repeated thermoplasticity.

[0010] Furthermore, in order to solve the above-mentioned problems, a method for producing a thermosetting resin according to one embodiment of the present disclosure is a method for producing a thermosetting resin having a benzoxazine ring structure in a main chain, the method including: a step (s1) of reacting a bifunctional phenol compound (A), an aliphatic diamine compound (B), and an aldehyde compound (D); optionally a step (s2) of reacting the bifunctional phenol compound (A), a (poly)oxyalkylenediamine compound (C), and the aldehyde compound (D); and optionally a step (s3) of reacting a monofunctional phenol compound (E); when the step (s2) is not included, the method is considered to include the step (s3); when the step (s2) is included, the aliphatic diamine compound (B) is an aliphatic diamine having a linear alkylene group with 6 to 12 carbon atoms; and when the step (s2) is not included, the aliphatic diamine compound (B) is an aliphatic diamine having a linear alkylene group with 8 to 12 carbon atoms; The (poly)oxyalkylenediamine compound (C) has a (poly)oxyethylene group and / or a (poly)oxypropylene group.

[0011] According to one aspect of the present disclosure, it is possible to realize a benzoxazine-based thermosetting resin that is excellent in flexibility before curing. Also, according to one aspect of the present disclosure, it is possible to provide a benzoxazine-based resin that is excellent in decomposition temperature and toughness before and after curing, and a method for producing the same.

[0012] FIG. 1 shows DMA curves of various films.

[0013] [1. Thermosetting Resin] An example of an embodiment of the present disclosure will be described in detail below, but the present disclosure is not limited thereto. In this specification, unless otherwise specified, "A to B" representing a numerical range means "A or more and B or less." In addition, in this disclosure, a thermosetting resin that has not been heated at all may be referred to as an "uncured resin."

[0014] The examples of Patent Document 1 disclose a phenol-terminated Bz (hereinafter referred to as C6Bz) having a structural unit derived from an aliphatic diamine having 6 carbon atoms (hexamethylenediamine). However, the present inventors have found that there is room for further improvement in C6Bz from the viewpoint of flexibility before curing.

[0015] According to one aspect of the present disclosure, the present inventors have discovered that by introducing structural units derived from an aliphatic diamine having 8 to 12 carbon atoms into a benzoxazine structure, a benzoxazine-based thermosetting resin with excellent flexibility before curing can be obtained. Furthermore, according to another aspect of the present disclosure, the present inventors have discovered that by introducing structural units derived from an aliphatic diamine having 6 to 12 carbon atoms and structural units derived from a (poly)oxyalkylenediamine compound into a benzoxazine structure, a benzoxazine-based thermosetting resin with excellent decomposition temperature and toughness before and after curing can be obtained. Furthermore, this thermosetting resin makes it possible to obtain an uncured molded product that exhibits thermoplasticity even before curing. In other words, this thermosetting resin can also be said to be a thermosetting thermoplastic benzoxazine.

[0016] The thermosetting resin of the present disclosure has a benzoxazine ring structure in the main chain, as represented by the following general formula (I): In this specification, a thermosetting resin having a benzoxazine ring structure is also referred to as a benzoxazine resin.

[0017] [In the general formula (I), Ar １ and Ar ２ may be the same or different and represent a tetravalent aromatic group derived from the bifunctional phenol compound (A), n represents an integer of 0 or more, R １ represents a linear alkylene group having 8 to 12 carbon atoms derived from the aliphatic diamine compound (B) when n=0, and represents a linear alkylene group having 6 to 12 carbon atoms derived from the aliphatic diamine compound (B) when n=1 or more, and R ２ represents a (poly)oxyalkylene group derived from the (poly)oxyalkylenediamine compound (C); when n = 0, at least one of the two ends of the main chain is a group represented by the following general formula (II) derived from the monofunctional phenol compound (E), and the two ends may be the same or different; when n = 0, m represents an integer of 2 or more; and when n = 1 or more, m represents an integer of 1 or more; the repeating unit represented by m and the repeating unit represented by n are repeated randomly, repeated as blocks, or are in the form of an alternating copolymer.

[0018] [In the general formula (II), X represents a hydrogen atom or an organic group having 1 to 20 carbon atoms, and 1 represents an integer of 0 to 3.] In the general formula (I), Ar １ and Ar ２ represents a tetravalent aromatic group derived from the bifunctional phenol compound (A). The bifunctional phenol compound (A) is preferably one having a structure in which its OH group and the ortho position relative to the OH group can be incorporated into a benzoxazine ring.

[0019] Examples of the bifunctional phenol compound (A) include biphenol compounds, dihydroxydiphenyl ether compounds, dihydroxydiphenylmethane compounds (including derivatives, the same applies hereinafter), dihydroxydiphenylethane compounds, dihydroxydiphenylpropane compounds, dihydroxydiphenylbutane compounds, dihydroxydiphenylcycloalkane compounds (for example, dihydroxydiphenylcyclohexane compounds), dihydroxydiphenyl ketone compounds, dihydroxydiphenylfluorene compounds, dihydroxydiphenylbenzene compounds, and other dihydroxydiphenyl compounds (also known as bisphenol compounds).

[0020] Here, in the general formula (I), when n = 0, examples of the bifunctional phenol compound (A) include biphenol compounds, dihydroxydiphenyl ether compounds, dihydroxydiphenylmethane compounds (including derivatives, the same applies hereinafter), dihydroxydiphenylethane compounds, dihydroxydiphenylpropane compounds, dihydroxydiphenylbutane compounds, dihydroxydiphenylcycloalkane compounds, dihydroxydiphenyl ketone compounds, dihydroxydiphenylfluorene compounds, dihydroxydiphenylbenzene compounds, and other dihydroxydiphenyl compounds.

[0021] In the general formula (I), when n is 1 or more, examples of the bifunctional phenol compound (A) include biphenol compounds, dihydroxydiphenyl ether compounds, dihydroxydiphenylmethane compounds, dihydroxydiphenylethane compounds, dihydroxydiphenylpropane compounds, dihydroxydiphenylbutane compounds, dihydroxydiphenylcycloalkane compounds, dihydroxydiphenyl ketone compounds, dihydroxydiphenylfluorene compounds, dihydroxydiphenylbenzene compounds, and other dihydroxydiphenyl compounds.

[0022] Examples of biphenol compounds include 4,4'-biphenol and 2,2'-biphenol.

[0023] Examples of the dihydroxydiphenyl ether compound include 4,4'-dihydroxydiphenyl ether and 2,2'-dihydroxydiphenyl ether.

[0024] Examples of the dihydroxydiphenylmethane compound include bis(4-hydroxyphenyl)diphenylmethane, bis(4-hydroxyphenyl)methane (also known as 4,4'-dihydroxydiphenylmethane, commonly known as bisphenol F), and 2,2'-dihydroxydiphenylmethane.

[0025] Examples of dihydroxydiphenylethane compounds include 1,1-bis(4-hydroxyphenyl)-1-phenylethane and 1,1-bis(4-hydroxyphenyl)ethane (commonly known as bisphenol E).

[0026] Examples of dihydroxydiphenylpropane compounds include 2,2-bis(4-hydroxyphenyl)propane (commonly known as bisphenol A or BPA), 2,2-bis(4-hydroxyphenyl)hexafluoropropane, 2,2-bis(3-methyl-4-hydroxyphenyl)propane, 2,2-bis(4-hydroxy-3-isopropylphenyl)propane, 5,5'-(1-methylethylidene)-bis[1,1'-(bisphenyl)-2-ol]propane, 1,1-bis(4-hydroxyphenyl)propane, and 1,1-bis(4-hydroxyphenyl)-2-methylpropane.

[0027] Examples of dihydroxydiphenylbutane compounds include 1,1-bis(4-hydroxyphenyl)butane and 2,2-bis(4-hydroxyphenyl)butane (commonly known as bisphenol B).

[0028] Examples of dihydroxydiphenylcycloalkane compounds include 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane, 1,1-bis(4-hydroxyphenyl)cyclohexane (bisphenol Z), and 1,1-bis(4-hydroxyphenyl)cyclopentane.

[0029] The dihydroxydiphenyl ketone compound includes 4,4'-dihydroxybenzophenone.

[0030] Examples of dihydroxydiphenylfluorene compounds include 9,9-bis(4-hydroxyphenyl)fluorene.

[0031] Examples of the dihydroxydiphenylbenzene compound include 1,3-bis(4-hydroxyphenoxy)benzene and 1,4-bis(3-hydroxyphenoxy)benzene.

[0032] Other dihydroxydiphenyl compounds include bis(4-hydroxyphenyl)-2,2-dichloroethylene, bis(4-hydroxyphenyl)sulfone, 1,3-bis(2-(4-hydroxyphenyl)-2-propyl)benzene, 1,4-bis(2-(4-hydroxyphenyl)-2-propyl)benzene, 4,4'-[1,3-phenylenebis(1-methyl-ethylidene)]bisphenol (Mitsui Chemicals, Ltd., "Bisphenol M"), and 4,4'-[1,4-phenylenebis(1-methyl-ethylidene)]bisphenol (Mitsui Chemicals, Ltd., "Bisphenol P").

[0033] Of these, 4,4'-dihydroxydiphenyl ether, bis(4-hydroxyphenyl)methane, 2,2-bis(4-hydroxyphenyl)propane and the like are preferred, with 2,2-bis(4-hydroxyphenyl)propane being more preferred.

[0034] In general formula (I), R １represents a divalent linear alkylene group having 8 to 12 carbon atoms (when n = 0) or 6 to 12 carbon atoms (when n = 1 or more) derived from the aliphatic diamine compound (B). That is, examples of the aliphatic diamine compound (B) include diamine compounds having a linear alkylene group having 8 to 12 carbon atoms (when n = 0) or 6 to 12 carbon atoms (when n = 1 or more). In the former case, preferred are diamine compounds having a saturated hydrocarbon group with a main chain skeleton having 8 to 12 carbon atoms, such as 1,8-octanediamine (octamethylenediamine), 1,9-nonanediamine (nonamethylenediamine), 1,10-decanediamine (decamethylenediamine), 1,11-undecanediamine (undecamethylenediamine), and 1,12-dodecanediamine (dodecamethylenediamine). In the latter case (when n is 1 or more), a diamine compound having a linear alkylene group with 6 carbon atoms, such as 1,6-hexanediamine (hexamethylenediamine), is suitable.

[0035] In general formula (I), R ２ represents a divalent (poly)oxyalkylene group derived from a (poly)oxyalkylene diamine compound (C) having a (poly)oxyalkylene skeleton and two amino terminal groups. In this specification, the (poly)oxyalkylene group includes a monooxyalkylene group (comprising one oxyalkylene group) and a polyoxyalkylene group (comprising multiple oxyalkylene groups). The (poly)oxyalkylene diamine compound (C) preferably has a (poly)oxyethylene group and / or a (poly)oxypropylene group as the (poly)oxyalkylene group. Examples of the (poly)oxyalkylene diamine compound (C) include Jeffamine D-230, Jeffamine D-400, Jeffamine D-2000, and Jeffamine D-4000 from the Jeffamine (registered trademark) D-series. Particularly preferred is Jeffamine D-2000. The thermosetting resin of the present disclosure contains a divalent (poly)oxyalkylene group derived from a (poly)oxyalkylenediamine compound, thereby making it possible to increase the toughness of the thermosetting resin before and after curing.

[0036] Furthermore, to synthesize the thermosetting resin of the present disclosure, an aldehyde compound (D) may be used. The aldehyde compound (D) is not particularly limited, but formaldehyde is preferred. The formaldehyde can be used in the form of paraformaldehyde, which is a polymer thereof, or formalin, which is an aqueous solution thereof.

[0037] The monofunctional phenol compound (E) is not particularly limited, but preferred examples include phenol, o-cresol, m-cresol, p-cresol, p-tert-butylphenol, p-octylphenol, p-cumylphenol, dodecylphenol, o-phenylphenol, p-phenylphenol, 1-naphthol, 2-naphthol, m-methoxyphenol, p-methoxyphenol, m-ethoxyphenol, p-ethoxyphenol, 3,4-dimethylphenol, 3,5-dimethylphenol, etc. Among these, phenol is preferred.

[0038] In general formula (I), m represents the degree of polymerization and is an integer of 1 or more, but from the viewpoint of improving the mechanical properties before and after curing, m is preferably 2 or more, more preferably 3 or more, and even more preferably 5 or more. Furthermore, from the viewpoint of maintaining fluidity during molding, m is preferably 500 or less, more preferably 300 or less, even more preferably 200 or less, and particularly preferably 100 or less.

[0039] In general formula (I), n represents the degree of polymerization and is an integer of 0 or more, but from the viewpoint of improving flexibility before curing, n is preferably 0. Furthermore, from the viewpoint of improving mechanical properties before and after curing, n is preferably 1 or more, more preferably 2 or more, even more preferably 3 or more, and particularly preferably 5 or more. Furthermore, from the viewpoint of maintaining fluidity during molding, n is preferably 500 or less, more preferably 300 or less, even more preferably 200 or less, and particularly preferably 100 or less.

[0040] Furthermore, when n is 1 or greater, the ratio of m to n is preferably n / m = 1 / 0.1 to 1 / 100. If the ratio of m to n is within the above range, a thermosetting resin that is excellent in decomposition temperature and toughness before and after curing can be obtained.

[0041] The thermosetting resin of the present disclosure may contain a structure other than the benzoxazine ring structure represented by general formula (I). For example, it may have a structure derived from a monocyclic phenol compound for terminally capping the structure represented by general formula (I). Furthermore, the thermosetting resin of the present disclosure may contain a structure derived from an aliphatic monoamine or a (poly)oxyalkylene monoamine compound.

[0042] In X of the general formula (II), examples of the "organic group having 1 to 20 carbon atoms" include methyl, ethyl, tert-butyl, octyl, dodecyl, phenyl, cumyl, methoxy, and ethoxy.

[0043] In the thermosetting resin of the present disclosure, when n = 0, the weight average molecular weight (Mw) measured by GPC is preferably 1,000 or more, more preferably 1,500 or more, even more preferably 2,000 or more, even more preferably 2,500 or more, and particularly preferably 3,000 or more, from the viewpoint of improving mechanical properties before and after curing. When n = 0, Mw may be 4,000 or more, or may be 5,000 or more. When n = 1 or more, Mw is preferably 10,000 or more, and from the viewpoint of improving mechanical properties before and after curing, Mw is more preferably 15,000 or more. Furthermore, when n = 0, from the viewpoint of availability and processability, it is preferably less than 10,000, more preferably 8,000 or less, even more preferably 7,000 or less, even more preferably 6,000 or less, and even more preferably 5,000 or less. When n = 1 or more, the weight average molecular weight (Mw) is preferably 100,000 or less.

[0044] [2. Method for producing thermosetting resin] The method for producing a thermosetting resin disclosed herein is a method for producing a thermosetting resin having a benzoxazine ring structure in its main chain, and includes: a step (s1) of reacting a bifunctional phenol compound (A), an aliphatic diamine compound (B), and an aldehyde compound (D); optionally, a step (s2) of reacting the bifunctional phenol compound (A), a (poly)oxyalkylenediamine compound (C), and the aldehyde compound (D); and optionally, a step (s3) of reacting a monofunctional phenol compound (E), wherein the step (s2) is not included in the method, and the step (s3) is included in the method, and when the step (s2) is included, the aliphatic diamine compound (B) is an aliphatic diamine having a linear alkylene group with 6 to 12 carbon atoms, and when the step (s2) is not included, the aliphatic diamine compound (B) is an aliphatic diamine having a linear alkylene group with 8 to 12 carbon atoms, The (poly)oxyalkylenediamine compound (C) is characterized in that it is a (poly)oxyalkylenediamine compound having a (poly)oxyethylene group and / or a (poly)oxypropylene group.

[0045] According to this method for producing a thermosetting resin, it is possible to obtain a thermosetting resin that is excellent in flexibility before curing and / or decomposition temperature and toughness before and after curing. Furthermore, by reacting the monofunctional phenol compound (E) in step (s3), reactive terminals can be blocked to prevent gelation. Note that the matters already explained in the section [1. Thermosetting Resin] will not be explained again.

[0046] Step (s1) is a step of reacting a bifunctional phenol compound (A), an aliphatic diamine compound (B), and an aldehyde compound (D) to produce a unit having a degree of polymerization m represented by general formula (I).

[0047] Step (s2) is a step of reacting a bifunctional phenol compound (A), a (poly)oxyalkylenediamine compound (C), and an aldehyde compound (D) to produce a unit having a degree of polymerization n represented by general formula (I).

[0048] Step (s1) and step (s2) may be performed simultaneously, or step (s1) may be performed first followed by step (s2), or step (s2) may be performed first followed by step (s1). That is, after the reaction of step (s1) has progressed, the materials for step (s2) may be added to the same system to perform step (s2), or vice versa. Alternatively, step (s1) and step (s2) may be performed in separate systems, and then the resulting products may be reacted in a single system. In other words, the production method of the present disclosure may include a step of reacting a bifunctional phenol compound (A), an aliphatic diamine compound (B), a (poly)oxyalkylenediamine compound (C), and an aldehyde compound (D). Furthermore, in the production method of the present disclosure, the aliphatic diamine compound (B) and the (poly)oxyalkylenediamine compound (C) may be added simultaneously or sequentially. From the perspective of ease of operation, it is preferable that step (s1) and step (s2) be performed simultaneously. When the above manufacturing method includes step (s2), step (s3) may or may not be included.

[0049] In the above production method, step (s1) of reacting a bifunctional phenol compound (A), an aliphatic diamine compound (B), and an aldehyde compound (D) and step (s3) of reacting a monofunctional phenol compound (E) may be performed simultaneously, or step (s1) may be performed first and step (s3) may be performed later. That is, after the reaction of step (s1) has progressed, materials for step (s3) may be added to the same system to perform step (s3). From the perspective of operational simplicity, it is preferable that step (s1) and step (s3) be performed simultaneously. It can also be said that the production method according to one embodiment of the present invention may include a step of reacting a bifunctional phenol compound (A), an aliphatic diamine compound (B), an aldehyde compound (D), and a monofunctional phenol compound (E).

[0050] When the above production method includes steps (s1), (s2), and (s3), steps (s1), (s2), and (s3) may be performed simultaneously, steps (s1) and (s2) may be performed simultaneously and step (s3) may be performed later, step (s1) may be performed first and steps (s2) and (s3) may be performed simultaneously and step (s2) may be performed later, step (s1) may be performed first and step (s2) and step (s3) may be performed simultaneously and step (s2) may be performed later, step (s1) may be performed first and step (s2) may be intermediate and step (s3) may be performed later, or step (s2) may be performed first, step (s1) may be intermediate and step (s3) may be performed later. In other words, the production method of the present disclosure may include a step of reacting a bifunctional phenol compound (A), an aliphatic diamine compound (B), a (poly)oxyalkylenediamine compound (C), an aldehyde compound (D), and a monofunctional phenol compound (E). In the production method of the present disclosure, the aliphatic diamine compound (B), the (poly)oxyalkylenediamine compound (C), and the monofunctional phenol compound (E) may be added simultaneously or sequentially. From the viewpoint of ease of operation, it is preferable that step (s1), step (s2), and step (s3) are performed simultaneously.

[0051] It is also known that benzoxazine polymers have poor stability (storage stability) in a solution state dissolved in a solvent and are prone to gelation. In the method described in Patent Document 1, the addition of a monofunctional phenol compound can cap reactive terminals to prevent gelation, but the inventors' studies have revealed that it is difficult to obtain benzoxazine with a high molecular weight because the addition inhibits the polymerization reaction that grows the molecular weight.

[0052] In the production method of the present disclosure, the molar ratio of the bifunctional phenol (A), the aliphatic diamine compound (B), and the (poly)oxyalkylenediamine compound (C) in total is preferably bifunctional phenol (A) / (aliphatic diamine compound (B)+(poly)oxyalkylenediamine compound (C))=10 / 1 to 1 / 10, more preferably 2 / 1 to 1 / 2. When the molar ratio of the bifunctional phenol (A), the aliphatic diamine compound (B), and the (poly)oxyalkylenediamine compound (C) in total is within the above range, a high-molecular-weight thermosetting resin that is less likely to gel during production can be obtained.

[0053] In the above production method, when n = 0, the molar ratio of the bifunctional phenol compound (A) to the aliphatic diamine compound (B) is preferably 1.0 / 1.0 to 1.0 / 2.0, and more preferably 5.0 / 10.0 to 7.5 / 10.0. When the ratio is within this range, gelation during production is unlikely to occur and a high molecular weight product is likely to be obtained.

[0054] In the production method of the present disclosure, the molar ratio of the (poly)oxyalkylenediamine compound (C) to the aliphatic diamine compound (B) is preferably (poly)oxyalkylenediamine compound (C) / aliphatic diamine compound (B) = 1 / 0.1 to 1 / 100, and more preferably 1 / 1 to 1 / 9. When the molar ratio of the (poly)oxyalkylenediamine compound (C) to the aliphatic diamine compound (B) is within the above range, a thermosetting resin excellent in decomposition temperature and toughness before and after curing can be obtained.

[0055] In the production method of the present disclosure, the molar ratio of the bifunctional phenol compound (A) to the aldehyde compound (D) is preferably 1 / 1 to 1 / 20, and more preferably 1 / 2 to 1 / 6. When the molar ratio of the bifunctional phenol compound (A) to the aldehyde compound (D) is within the above range, a benzoxazine ring can be suitably produced.

[0056] In the above production method, the molar ratio of the aliphatic diamine compound (B) to the monofunctional phenol compound (E) is preferably 10.0 / 1.0 to 10.0 / 5.0 and / or 10.0 / 5.0 to 10.0 / 7.5, in which case gelation during production is unlikely and a high molecular weight product is likely to be obtained.

[0057] In the production method of the present disclosure, the solvent is not particularly limited as long as it can dissolve the raw materials, and examples thereof include halogenated solvents alone such as chloroform; non-halogenated hydrocarbon solvents such as toluene; mixed solvents of non-halogenated hydrocarbon solvents and aliphatic alcohol solvents, such as a mixed solvent of toluene and methanol, a mixed solvent of toluene and ethanol, or a mixed solvent of toluene and isobutanol; and ether-based solvents alone such as tetrahydrofuran (THF).

[0058] The non-halogenated hydrocarbon solvent in the mixed solvent is a hydrocarbon solvent that does not contain halogen atoms and does not contain heteroatoms such as oxygen atoms, nitrogen atoms, or sulfur atoms, and may be an aliphatic hydrocarbon, an alicyclic hydrocarbon, an aromatic hydrocarbon, or the like. Among these, toluene and / or xylene are preferred, and toluene is more preferred. The aliphatic alcohol solvent is a compound in which one or more hydroxyl groups are bonded to an aliphatic hydrocarbon. Among these, at least one solvent selected from the group consisting of methanol, ethanol, propanol, and butanol (including structural isomers) is preferred, and at least one solvent selected from the group consisting of methanol, ethanol, and propanol is more preferred.

[0059] The volume ratio of the non-halogenated hydrocarbon solvent to the aliphatic alcohol solvent is preferably (non-halogenated hydrocarbon solvent) / (aliphatic alcohol solvent)=50 / 50 to 80 / 20.

[0060] When n = 0, the reaction temperature and reaction time are not particularly limited, but the reaction can usually be carried out for several tens of minutes to several hours at a temperature of from room temperature to about 120°C, or from room temperature to about 150°C. In one embodiment of the present invention, the reaction is preferably carried out at a temperature of from 30 to 110°C, or from 30 to 150°C, for 20 minutes to 5 hours, or from 20 minutes to 9 hours, because the reaction proceeds to a polymer that can exhibit the function of a thermosetting resin according to one embodiment of the present invention.

[0061] When n is 1 or more, the reaction temperature in step (s1), step (s2) and / or step (s3) is preferably 25 to 150° C., more preferably 40 to 120° C. When n is 1 or more, the reaction time in step (s1), step (s2) and / or step (s3) is preferably 0.5 to 10 hours, more preferably 1 to 5 hours.

[0062] In addition, removing the water produced during the reaction from the system is also an effective method for promoting the reaction. After the reaction, a polymer can be precipitated by adding a large amount of a poor solvent such as methanol to the solution, and the polymer can be separated and dried to obtain the desired polymer.

[0063] In the above production method, the obtained product may be washed with an aqueous solution of sodium bicarbonate or the like. After washing, dehydration may be carried out with sodium sulfate or the like.

[0064] In the reacting step (s1) and / or step (s2), it is preferable to react the bifunctional phenol compound (A), optionally the diamine compound (B), optionally the (poly)oxyalkylenediamine compound (C), and the aldehyde compound (D) in a solvent while heating. In the reacting step (s3), it is preferable to further react the monofunctional phenol compound (E) in a solvent while heating.

[0065] 3. Composition It is also possible to prepare and use a thermosetting composition that contains the thermosetting resin of the present disclosure as a main component and other thermosetting resins, thermoplastic resins, and compounding agents as secondary components.

[0066] Other thermosetting resins include, for example, epoxy resins, thermosetting modified polyphenylene ether resins, thermosetting polyimide resins, silicon resins, melamine resins, urea resins, allyl resins, phenolic resins, unsaturated polyester resins, bismaleimide resins, alkyd resins, furan resins, polyurethane resins, and aniline resins.

[0067] Examples of the thermoplastic resin include a thermoplastic epoxy resin and a thermoplastic polyimide resin.

[0068] Examples of compounding agents include, as needed, flame retardants, nucleating agents, antioxidants, antiaging agents, heat stabilizers, light stabilizers, ultraviolet absorbers, lubricants, flame retardant assistants, antistatic agents, antifogging agents, fillers, softeners, plasticizers, and colorants. These may be used alone or in combination of two or more. Reactive or non-reactive solvents may also be used.

[0069] [4. Uncured Molded Body (Molded Body of Thermosetting Resin) and Partially Cured Molded Body] The thermosetting resin or composition thereof of the present disclosure has moldability even before curing. Therefore, depending on the application and purpose, an uncured molded body obtained by molding the thermosetting resin or composition without curing, or a partially cured molded body that is only partially cured but not completely cured, can be used. The molding temperature (the highest temperature in the case of a gradual temperature increase) is not particularly limited, but is preferably above room temperature and below 200°C, more preferably above 40°C and below 180°C, even more preferably above 60°C and below 160°C, and most preferably above 100°C and below 160°C. If the molding temperature is below 200°C, curing will not proceed and the desired uncured molded body will be obtained.

[0070] The dimensions and shapes of the uncured molded body and the partially cured molded body are not particularly limited, and examples thereof include film, sheet, plate, and block shapes, and may further include other portions (for example, an adhesive layer).

[0071] The uncured molded product and the partially cured molded product can be used as precursors of the cured molded product described later, and can also be used, for example, as a curable adhesive sheet.

[0072] From the viewpoint of decomposition temperature, it is preferable that the uncured molded body and the partially cured molded body have a small weight loss rate. The weight loss rate is the percentage of the weight loss of the thermosetting resin after heating at a predetermined temperature for a predetermined time, with the weight of the thermosetting resin before thermal curing being taken as 100. The weight loss rate may be determined by thermogravimetric analysis (TGA). The weight loss rate is preferably 5% or less, and more preferably 3% or less. Furthermore, the smaller the weight loss rate, the more preferable it is, but for example, the lower limit may be 0.01% or more. This weight loss rate may be measured, for example, at a temperature assuming thermoplastic processing of the uncured molded body, or at a temperature assuming curing of the uncured molded body, but the latter is more preferable.

[0073] The uncured molded product and the partially cured molded product preferably have a high decomposition onset temperature. The decomposition onset temperature may be determined from the TG inflection point using the TGA described above. The decomposition onset temperature is preferably 250°C or higher, and more preferably 255°C or higher. This can suppress decomposition of the compound when curing the uncured molded product.

[0074] From the viewpoint of excellent toughness and high elongation of the uncured molded body and partially cured molded body, the glass transition temperature (Tg) of the uncured molded body is preferably 23° C. or lower, more preferably 0° C. or lower, and most preferably −10° C. or lower. Furthermore, from the viewpoint of the decomposition temperature during curing, the glass transition temperature of the uncured molded body is preferably −150° C. or higher, more preferably −100° C. or higher, and preferably −60° C. or higher. If the glass transition temperature is within the above range, the uncured molded body will exhibit excellent toughness and high elongation even at around room temperature (25° C.).

[0075] The mechanical properties of the uncured molded body and the partially cured molded body may be evaluated, for example, by the tensile modulus, tensile strength at break, and tensile elongation at break. Each property may be measured using a known tensile tester. The smaller the tensile modulus and tensile strength at break, the better the flexibility. On the other hand, the larger the tensile elongation at break, the better the flexibility.

[0076] From the viewpoint of excellent toughness, high elongation, and flexibility of the uncured molded body, the tensile modulus of the uncured molded body is preferably 10 GPa or less, more preferably 5 GPa or less, and most preferably 1 GPa or less. Among these, when n = 1 or more, it is preferably 3 GPa or less, more preferably 1 GPa or less, and most preferably 0.1 GPa or less. Furthermore, from the viewpoint of ease of handling of the uncured molded body, the tensile modulus of the uncured molded body is preferably 0.00001 GPa or more, more preferably 0.0001 GPa or more, and most preferably 0.001 GPa or more. Among these, when n = 1 or more, it is preferably 0.0001 GPa or more, more preferably 0.005 GPa or more, and most preferably 0.001 GPa or more.

[0077] From the viewpoint of flexibility, the tensile breaking strength of the uncured molded body is preferably 500 MPa or less, more preferably 100 MPa or less, and most preferably 10 MPa or less. From the viewpoint of ease of handling and resistance to breakage of the uncured molded body and partially cured molded body, the tensile breaking strength of the uncured molded body is preferably 0.01 MPa or more, more preferably 0.1 MPa or more, and most preferably 1 MPa or more. Among these, when n = 1 or more, the tensile breaking strength is preferably 0.1 MPa or more, more preferably 1 MPa or more, and most preferably 1.5 MPa or more.

[0078] From the viewpoint of excellent toughness and high elongation of the uncured molded body and partially cured molded body, the tensile elongation at break of the uncured molded body is preferably 10% or more, more preferably 50% or more, and most preferably 100% or more. Among these, when n=1 or more, it is preferably 3% or more, more preferably 10% or more, and most preferably 80% or more.

[0079] Furthermore, the tensile elongation at break of the uncured molded body and the partially cured molded body is preferably at least 1 time, and more preferably at least 1.5 times, the tensile elongation at break of the cured molded body described below. When the tensile elongation at break of the uncured molded body is at least 1 time the tensile elongation at break of the cured molded body, the uncured molded body has superior toughness and a higher elongation than the cured molded body.

[0080] The uncured and partially cured molded articles have excellent toughness, which allows them to be deformed into any shape. For example, an uncured film with excellent toughness will not tear or crack even if it is rolled or deformed into any shape.

[0081] The uncured and partially cured molded bodies preferably possess both thermoplastic remoldability and toughness during remolding. Thermoplastic remoldability refers to the ability of an uncured or partially cured molded body to be deformed into a desired shape and then return to its original shape when heated at a temperature that does not completely cure the uncured or partially cured molded body. The temperature that does not completely cure the uncured or partially cured molded body is 200°C or lower. Furthermore, toughness during remolding refers to the property of not breaking or cracking before and after heating the uncured or partially cured molded body at a temperature that does not completely cure the uncured or partially cured molded body. Furthermore, the uncured or partially cured molded body maintains its remoldability and toughness even after undergoing deformation and remolding by heating one or more times. This property is referred to herein as "repeated thermoplasticity." This property makes the uncured molded body easier to handle and broadens the range of uses for the uncured molded body.

[0082] An uncured molded product refers to a product with a degree of cure of less than 1%. For example, the degree of cure of an uncured resin that has not been heated at all may be 0%, and the degree of cure of a cured molded product that has been sufficiently heat-treated and confirmed to have disappeared from the peak corresponding to curing in DSC may be 100%. The degree of cure of the uncured molded product may be calculated from the ratio of the areas of the curing exothermic peaks obtained by DSC of the uncured resin and the uncured molded product.

[0083] The degree of curing of the partially cured molded body is 1% or more and 99% or less, and from the viewpoint of repeated thermoplasticity, it is preferably 1% or more and less than 90%. If the degree of curing is less than 1%, the thermoplastic remolding ability is good, but the toughness during remolding may be insufficient. Furthermore, if the degree of curing is greater than 99%, the thermoplastic remolding ability may be insufficient. Among these, depending on the application to which the partially cured molded body is applied or the required processing method, it is preferable to use a partially cured molded body with a lower degree of curing when emphasis is placed on thermoplastic remolding ability. Furthermore, it is preferable to use a partially cured molded body with a higher degree of curing ability when emphasis is placed on toughness during remolding. The degree of curing of the partially cured molded body may be calculated from the ratio of the areas of the curing exothermic peaks obtained by DSC of the uncured resin and the partially cured molded body.

[0084] The degree of curing of the partially cured molded body is more preferably 2% or more and 80% or less, more preferably 2% or more and 70% or less, even more preferably 2% or more and 60% or less, even more preferably 3% or more and 40% or less, and most preferably 3% or more and 30% or less.

[0085] Furthermore, the uncured molded body and the partially cured molded body preferably have flexibility. Flexibility may be evaluated, for example, by a mandrel test in accordance with JIS K-5600-5-1:1999. In the mandrel test, the smaller the bending radius, the higher the flexibility of the material can be evaluated. When evaluated by the mandrel test, the bending radius is preferably 2 mm or less, and more preferably 1 mm or less. According to this, the uncured molded body and the partially cured molded body have flexibility that can withstand a 180° bending.

[0086] [5. Cured Molded Body (Cured Molded Body)] A cured molded body can be obtained by applying heat to a molded body (uncured molded body) or a partially cured molded body of the thermosetting resin described above to cure it. Alternatively, a cured molded body can be obtained by molding the thermosetting resin or a composition thereof of the present disclosure and simultaneously applying heat to cure it, without first forming an uncured or partially cured molded body. The curing temperature (the highest temperature in the case of a gradual temperature increase) is not particularly limited, but is preferably 200°C or higher and 300°C or lower, more preferably 210°C or higher and 280°C or lower, even more preferably 220°C or higher and 260°C or lower, and most preferably 240°C or higher and 260°C or lower. If the curing temperature is 200°C or higher, a sufficiently cured molded body can be obtained. Furthermore, if the curing temperature is lower than 300°C, thermal decomposition does not progress, and the desired cured molded body can be obtained. Here, the cured molded body of the present disclosure refers to one with a degree of curing of more than 99%.

[0087] When n = 1 or greater, the glass transition temperature (Tg) of the cured molded body is preferably 300°C or less, more preferably 250°C or less, and most preferably 200°C or less, from the viewpoint of excellent toughness and high elongation of the cured molded body. When n = 0, no upper limit is set for Tg. Furthermore, from the viewpoint of decomposition temperature, the glass transition temperature of the cured molded body is preferably -150°C or higher, more preferably -100°C or higher, and even more preferably -60°C or higher. If the glass transition temperature is within the above range, the cured molded body exhibits excellent toughness and high elongation even at around room temperature (25°C). Among these, when n = 0, the glass transition temperature of the cured molded body is preferably 100°C or higher, more preferably 150°C or higher. When n = 0, the glass transition temperature of the cured molded body may be 200°C or higher. If the glass transition temperature is within the above range, the cured molded body exhibits excellent heat resistance.

[0088] The thermal decomposition temperature (Td5) of the cured molded body refers to the temperature, measured in an environment where the uncured molded body is cured, at which the compound thermally decomposes and the weight decreases by 5%. From the viewpoint of the resistance to thermal decomposition of the cured molded body, the thermal decomposition temperature (Td5) is preferably 200°C or higher, more preferably 230°C or higher, and most preferably 250°C or higher.

[0089] From the viewpoint of excellent toughness and high elongation of the cured molded body, the tensile modulus of the cured molded body is preferably 10 GPa or less, more preferably 5 GPa or less, and most preferably 3 GPa or less. Of these, when n = 1 or more, the tensile modulus of the cured molded body is preferably 2 GPa or less. Furthermore, from the viewpoint of ease of handling of the cured molded body, the tensile modulus of the cured molded body is preferably 0.0001 GPa or more, more preferably 0.0005 GPa or more, and most preferably 0.001 GPa or more. Of these, when n = 0, the tensile modulus is preferably 0.1 GPa or more, more preferably 0.5 GPa or more, and most preferably 1 GPa or more.

[0090] From the viewpoint of resistance to breakage of the cured molded body, the tensile strength at break of the cured molded body is preferably 0.1 MPa or more, more preferably 1 MPa or more, and most preferably 1.5 MPa or more. Among these, when n=0, from the viewpoint of toughness, the tensile strength at break of the cured molded body is preferably 5 MPa or more, more preferably 10 MPa or more, and most preferably 50 MPa or more.

[0091] From the viewpoint of ease of handling of the cured molded body, the tensile strength at break of the cured molded body is preferably 1000 MPa or less, more preferably 500 MPa or less, and most preferably 100 MPa or less.

[0092] From the viewpoint of toughness, the tensile elongation at break of the cured molded article is preferably 0.1% or more, more preferably 1% or more, even more preferably 3% or more, and most preferably 5% or more. Among these, when n=1 or more, from the viewpoint of excellent toughness and high elongation of the cured molded article, the tensile elongation at break of the cured molded article is preferably 3% or more, more preferably 4% or more, and most preferably 5% or more.

[0093] Furthermore, the cured molded product preferably has flexibility similar to that of the uncured molded product and the partially cured molded product. Flexibility may be evaluated, for example, by a mandrel test in accordance with JIS K-5600-5-1:1999. When evaluated by the mandrel test, the bending radius is preferably 2 mm or less. This indicates that the cured molded product has flexibility sufficient to withstand a 180° bend.

[0094] The size and shape of the cured molded product are not particularly limited, and examples thereof include a film, sheet, plate, block, etc., and may further include other portions (for example, an adhesive layer).

[0095] The cured molded article can be suitably used for electronic components and electronic devices, and materials therefor, particularly for applications requiring excellent dielectric properties, such as multilayer substrates, laminates, sealants, adhesives, etc., and can also be used for other applications such as aircraft components, automobile components, building components, etc. In particular, the cured molded article of the present disclosure can be suitably used for producing semipregs, prepregs, and carbon fiber composite materials.

[0096] The cured molded article may contain reinforcing fibers to improve the mechanical strength of the cured molded article. Examples of reinforcing fibers include inorganic fibers, organic fibers, metal fibers, and hybrid reinforcing fibers that combine these. The reinforcing fibers may be one type or two or more types.

[0097] Examples of inorganic fibers include carbon fibers, graphite fibers, silicon carbide fibers, alumina fibers, tungsten carbide fibers, boron fibers, and glass fibers. Examples of organic fibers include aramid fibers, high-density polyethylene fibers, and other common nylon fibers and polyester fibers. Examples of metal fibers include stainless steel and iron fibers. Examples of metal fibers include carbon-coated metal fibers, which are metal fibers coated with carbon. Among these, carbon fibers are preferred as the reinforcing fibers from the viewpoint of increasing the strength of the cured product.

[0098] Generally, the carbon fibers are subjected to a sizing treatment, but they may be used as is. If necessary, fibers containing a small amount of sizing agent may be used, or the sizing agent may be removed by an existing method such as organic solvent treatment or heat treatment. Alternatively, the carbon fiber bundles may be opened in advance using air or a roller, and treated to facilitate impregnation of the resin between the carbon fiber single yarns. By reducing the amount of sizing agent used or removing the sizing agent, it is possible to suppress void formation and discoloration of the resin due to decomposition of the sizing agent at high temperatures.

[0099] One embodiment of the present invention also includes a prepreg or semipreg obtained by impregnating reinforcing fibers with the thermosetting resin or composition of the present disclosure. In this specification, semipreg refers to a composite in which reinforcing fibers are partially impregnated with the thermosetting resin or composition (semi-impregnated state) and integrated.

[0100] Furthermore, a prepreg can be obtained from the semipreg. For example, the semipreg can be further heated and melted to impregnate the reinforcing fibers with a resin, thereby obtaining a prepreg. In other words, in this specification, a prepreg can be said to be a material in which the degree of resin impregnation into the reinforcing fibers is more advanced than in a semipreg.

[0101] [6. Carbon Fiber Composite Material] The cured molded article of the present disclosure can be used as a carbon fiber composite material. Carbon fiber composite materials are also called carbon fiber reinforced plastics (CFRP). The method for producing the carbon fiber composite material is not particularly limited, and may include, for example, a method using semipreg or prepreg, which is a sheet of carbon fiber impregnated with resin, or a method of impregnating carbon fiber (bundle-like or woven) with liquid resin. The cured molded article of the present disclosure may be molded into a semipreg or prepreg, and the semipreg or prepreg may be used to produce a carbon fiber composite material.

[0102] Although a carbon fiber composite material is given as an example here, as mentioned above, the reinforcing fibers that can be used are not limited to carbon fibers. That is, one embodiment of the present invention also includes a fiber composite material obtained by impregnating a reinforcing fiber with the thermosetting resin or composition of the present disclosure and curing the thermosetting resin or composition.

[0103] The semipreg or prepreg may be obtained, for example, by stacking the cured molded article of the present disclosure on both sides of a sheet (carbon fiber plain weave material) in which carbon fibers have been pre-impregnated with resin, and pressing the sheet at a predetermined temperature and a predetermined pressure.

[0104] In addition to carbon fibers, the reinforcing fibers described in [5. Cured molded body (cured molded body)] may be used for the semipreg or prepreg.

[0105] Carbon fiber composite materials may be produced by laminating multiple semipregs or prepregs and pressing them at a predetermined temperature and pressure. This type of pressing can mainly suppress voids formed between the carbon fibers. It is more preferable to perform pressing under vacuum conditions (vacuum pressing). Vacuum pressing can also suppress voids formed between the resin. Vacuum pressing can also increase the heating rate compared to regular pressing. Alternatively, heating using a vacuum oven after regular pressing can also suppress voids formed between the resin.

[0106] The pressure is preferably 1 to 5 MPa, and more preferably 1 to 3 MPa. The temperature is preferably 50°C or higher, and more preferably 100°C or higher. The temperature is preferably 400°C or lower, and more preferably 300°C or lower.

[0107] The pressure and temperature may be increased stepwise. For example, the method for producing a carbon fiber composite material may include the steps of (1) treating at atmospheric pressure at 50 to 200°C for 5 to 20 minutes, (2) treating at 1 to 5 MPa at 50 to 200°C for 10 to 30 minutes, and (3) treating at 1 to 5 MPa at a temperature higher than 200°C and equal to or lower than 400°C for 1 to 5 hours.

[0108] When the temperature is increased during pressing, it is preferable to increase the temperature without removing the carbon fiber from the press, which can further suppress the formation of voids between the carbon fibers.

[0109] The laminated semipreg or prepreg may be covered with a release film, such as a polyimide (PI) film. Such a cover can reduce the amount of resin that bleeds out of the carbon fiber composite material.

[0110] [7. Summary] An embodiment of the present invention may include the following configuration: <1> A thermosetting resin represented by general formula (I) having a benzoxazine ring structure in the main chain.

[0111] [In the general formula (I), Ar １ and Ar ２ may be the same or different and represent a tetravalent aromatic group derived from the bifunctional phenol compound (A), n represents an integer of 0 or more, R １ represents a linear alkylene group having 8 to 12 carbon atoms derived from the aliphatic diamine compound (B) when n=0, and represents a linear alkylene group having 6 to 12 carbon atoms derived from the aliphatic diamine compound (B) when n=1 or more, and R ２represents a (poly)oxyalkylene group derived from the (poly)oxyalkylenediamine compound (C); when n = 0, at least one of the two ends of the main chain is a group represented by the following general formula (II) derived from the monofunctional phenol compound (E), and the two ends may be the same or different; when n = 0, m represents an integer of 2 or more; and when n = 1 or more, m represents an integer of 1 or more; the repeating unit represented by m and the repeating unit represented by n are repeated randomly, repeated as blocks, or are in the form of an alternating copolymer.

[0112] [In the general formula (II), X represents a hydrogen atom or an organic group having 1 to 20 carbon atoms, and 1 represents an integer of 0 to 3.] <2> The bifunctional phenol compound (A) is 2,2-bis(4-hydroxyphenyl)propane, 1,1-bis(4-hydroxyphenyl)-1-phenylethane, 2,2-bis(4-hydroxyphenyl)hexafluoropropane, 2,2-bis(4-hydroxyphenyl)butane, bis(4-hydroxyphenyl)diphenylmethane, 2,2-bis(3-methyl-4-hydroxyphenyl)propane, bis(4-hydroxyphenyl)-2,2-dichloroethylene, 1,1-bis(4-hydroxyphenyl)ethane, bis(4-hydroxyphenyl)methane, 2,2-bis(4-hydroxyphenyl)-2,2-dichloroethylene, The thermosetting resin according to <1>, wherein the (poly)oxyalkylenediamine compound (C) is at least one bifunctional phenol compound selected from the group consisting of 1,3-bis(2-(4-hydroxyphenyl)-2-propyl)benzene, 1,3-bis(2-(4-hydroxyphenyl)-2-propyl)benzene, bis(4-hydroxyphenyl)sulfone, 1,4-bis(2-(4-hydroxyphenyl)-2-propyl)benzene, 5,5'-(1-methylethylidene)-bis[1,1'-(bisphenyl)-2-ol]propane, 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane, and 1,1-bis(4-hydroxyphenyl)cyclohexane. <3> The thermosetting resin according to <1> or <2>, wherein the (poly)oxyalkylenediamine compound (C) has a (poly)oxyethylene group and / or a (poly)oxypropylene group. <4> The thermosetting resin according to any one of <1> to <3>, wherein in general formula (I), the ratio of m to n is n / m = 1 / 0.1 to 1 / 100. <5> A composition containing the thermosetting resin according to any one of <1> to <4>. <6> An uncured molded article obtained by molding the thermosetting resin according to any one of <1> to <4>. <7> The uncured molded article according to <6>, which has a bending radius of 2 mm or less in a mandrel test in accordance with JIS K-5600-5-1:1999. <8> A partially cured molded article obtained by partially curing the thermosetting resin according to any one of <1> to <4>, and having a degree of cure of 1% to 99%.<9> The partially cured molded article according to <8>, which has a bending radius of 2 mm or less in a mandrel test in accordance with JIS K-5600-5-1:1999. <10> A cured molded article obtained by curing the thermosetting resin according to any one of <1> to <4>. <11> The cured molded article according to <10>, which has a bending radius of 2 mm or less in a mandrel test in accordance with JIS K-5600-5-1:1999. <12> A thermosetting resin having a benzoxazine ring structure in its main chain, wherein an uncured molded body having a degree of cure of less than 1% obtained by molding the thermosetting resin, or a partially cured molded body having a degree of cure of 1 to 99% obtained by curing the thermosetting resin, has thermoplastic remoldability and toughness, wherein the thermoplastic remoldability refers to the property of the uncured molded body or the partially cured molded body being deformed into an arbitrary shape and then returning to the shape before deformation by heating at 200°C or less, and the toughness refers to the property of the uncured molded body or the partially cured molded body not breaking or cracking before or after the heating, and wherein the thermosetting resin has repeated thermoplasticity, maintaining the remoldability and toughness even when the deformation and heating are performed one or more times. <13> A method for producing a thermosetting resin having a benzoxazine ring structure in its main chain, comprising: step (s1) of reacting a bifunctional phenol compound (A), an aliphatic diamine compound (B), and an aldehyde compound (D); optionally step (s2) of reacting the bifunctional phenol compound (A), a (poly)oxyalkylenediamine compound (C), and the aldehyde compound (D); and optionally step (s3) of reacting a monofunctional phenol compound (E), wherein when step (s2) is not included, step (s3) is included; when step (s2) is included, the aliphatic diamine compound (B) is an aliphatic diamine having a linear alkylene group with 6 to 12 carbon atoms; and when step (s2) is not included, the aliphatic diamine compound (B) is an aliphatic diamine having a linear alkylene group with 8 to 12 carbon atoms; The method for producing a thermosetting resin, wherein the (poly)oxyalkylenediamine compound (C) has a (poly)oxyethylene group and / or a (poly)oxypropylene group.<14> The method for producing a thermosetting resin according to <13>, wherein the molar ratio of the aliphatic diamine compound (B) to the (poly)oxyalkylenediamine compound (C) is (poly)oxyalkylenediamine compound (C) / aliphatic diamine compound (B) = 1 / 0.1 to 1 / 100.

[0113] Another embodiment of the present invention may include the following configuration: <A1> A thermosetting resin represented by general formula (I) having a benzoxazine ring structure in the main chain.

[0114] [In formula (I), Ar １ and Ar ２ may be the same or different and represent a tetravalent aromatic group derived from the bifunctional phenol compound (A), R １ represents a linear alkylene group having 6 to 12 carbon atoms derived from the aliphatic diamine compound (B), and R ２represents a (poly)oxyalkylene group derived from the (poly)oxyalkylenediamine compound (C), m represents an integer of 1 or more, n represents an integer of 1 or more, and the repeating unit represented by m and the repeating unit represented by n are repeated randomly, repeated as a block, or are an alternating copolymer.] <A2> The bifunctional phenol compound (A) is 2,2-bis(4-hydroxyphenyl)propane, 1,1-bis(4-hydroxyphenyl)-1-phenylethane, 2,2-bis(4-hydroxyphenyl)hexafluoropropane, 2,2-bis(4-hydroxyphenyl)butane, bis(4-hydroxyphenyl)diphenylmethane, 2,2-bis(3-methyl-4-hydroxyphenyl)propane, bis(4-hydroxyphenyl)-2,2-dichloroethylene, 1,1-bis(4-hydroxyphenyl)ethane, bis(4-hydroxyphenyl)methane, 2,2-bis(4-hydroxyphenyl)- The thermosetting resin according to <A1>, wherein the (poly)oxyalkylenediamine compound (C) is at least one bifunctional phenol compound selected from the group consisting of 1,3-bis(2-(4-hydroxyphenyl)-2-propyl)benzene, 1,3-bis(2-(4-hydroxyphenyl)-2-propyl)benzene, bis(4-hydroxyphenyl)sulfone, 1,4-bis(2-(4-hydroxyphenyl)-2-propyl)benzene, 5,5'-(1-methylethylidene)-bis[1,1'-(bisphenyl)-2-ol]propane, 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane, and 1,1-bis(4-hydroxyphenyl)cyclohexane. <A3> The thermosetting resin according to <A1> or <A2>, wherein the (poly)oxyalkylenediamine compound (C) has a (poly)oxyethylene group and / or a (poly)oxypropylene group. <A4> The thermosetting resin according to any one of <A1> to <A3>, wherein in formula (I), the ratio of m to n is n / m = 1 / 0.1 to 1 / 100. <A5> A composition comprising the thermosetting resin according to any one of <A1> to <A4>. <A6> An uncured molded article obtained by molding the thermosetting resin according to any one of <A1> to <A4> or the composition according to <A5>.<A7> The uncured molded article according to <A6>, which has a bending radius of 2 mm or less in a mandrel test according to JIS K-5600-5-1:1999. <A8> A partially cured molded article obtained by partially curing the thermosetting resin according to any one of <A1> to <A4>, the composition according to <A5>, or the uncured molded article according to <A6>, and which has a degree of curing of 1% to 99%. <A9> The partially cured molded article according to <A8>, which has a bending radius of 2 mm or less in a mandrel test according to JIS K-5600-5-1:1999. <A10> A cured molded article obtained by curing the thermosetting resin according to any one of <A1> to <A4>, the composition according to <A5>, the uncured molded article according to <A6>, or the partially cured molded article according to <A8>. <A11> The cured molded article according to <A10>, having a bending radius of 2 mm or less in a mandrel test in accordance with JIS K-5600-5-1: 1999. <A12> A thermosetting resin having a benzoxazine ring structure in its main chain, wherein an uncured molded article having a degree of cure of less than 1% obtained by molding the thermosetting resin, or a partially cured molded article having a degree of cure of 1 to 99% obtained by curing the thermosetting resin, has thermoplastic remoldability and toughness, wherein the thermoplastic remoldability refers to the property of the uncured molded article or the partially cured molded article being deformed into an arbitrary shape and then returning to its original shape upon heating at 200°C or less, and wherein the toughness refers to the property of the uncured molded article or the partially cured molded article not breaking or cracking before or after the heating, and wherein the remoldability and toughness are maintained even after the deformation and the heating are performed one or more times.<A13> A method for producing a thermosetting resin having a benzoxazine ring structure in its main chain, comprising: a step (s1) of reacting a bifunctional phenol compound (A), an aliphatic diamine compound (B), and an aldehyde compound (D); and a step (s2) of reacting the bifunctional phenol compound (A), a (poly)oxyalkylenediamine compound (C), and the aldehyde compound (D), wherein the aliphatic diamine compound (B) is an aliphatic diamine having a linear alkylene group having 6 to 12 carbon atoms, and the (poly)oxyalkylenediamine compound (C) has a (poly)oxyethylene group and / or a (poly)oxypropylene group. <A14> The method for producing a thermosetting resin according to <A13>, wherein the molar ratio between the aliphatic diamine compound (B) and the (poly)oxyalkylenediamine compound (C) is (poly)oxyalkylenediamine compound (C) / aliphatic diamine compound (B) = 1 / 0.1 to 1 / 100. <A15> A prepreg or semipreg obtained by impregnating reinforcing fibers with the thermosetting resin according to any one of <A1> to <A4> or the composition according to <A5>. <A16> A fiber composite material obtained by impregnating reinforcing fibers with the thermosetting resin according to any one of <A1> to <A4> or the composition according to <A5>, and curing the thermosetting resin or the composition.

[0115] Yet another embodiment of the present invention may include the following configuration: <B1> A thermosetting resin represented by general formula (I') having a benzoxazine ring structure in the main chain.

[0116] [In the formula (I'), Ar １ represents a tetravalent aromatic group derived from the bifunctional phenol compound (A), and R １ represents a linear alkylene group having 8 to 10 carbon atoms derived from the aliphatic diamine compound (B), at least one of A and B is a group represented by the following general formula (II) derived from the monofunctional phenol compound (E), and A and B may be the same or different, and m represents an integer of 2 or greater.

[0117] [In formula (II), X represents a hydrogen atom or an organic group having 1 to 20 carbon atoms, and 1 represents an integer of 0 to 3.] <B2> A composition containing the thermosetting resin described in <B1>. <B3> An uncured molded article obtained by molding the thermosetting resin described in <B1> or the composition described in <B2>. <B4> A cured molded article obtained by curing the thermosetting resin described in <B1>, the composition described in <B2>, or the uncured molded article described in <B3>. <B5> A method for producing a thermosetting resin having a benzoxazine ring structure in its main chain, the method comprising: a step (s1) of reacting a bifunctional phenol compound (A), an aliphatic diamine compound (B), and an aldehyde compound (D); and a step (s3) of reacting a monofunctional phenol compound (E), wherein the aliphatic diamine compound (B) is an aliphatic diamine having a linear alkylene group having 8 to 10 carbon atoms.

[0118] Yet another embodiment of the present invention may include the following configuration: <C1> A thermosetting resin represented by general formula (I') having a benzoxazine ring structure in the main chain.

[0119] [In formula (I'), Ar1 represents a tetravalent aromatic group derived from the bifunctional phenol compound (A), R1 represents a linear alkylene group having 12 carbon atoms derived from the aliphatic diamine compound (B), at least one of A and B is a group represented by the following general formula (II) derived from the monofunctional phenol compound (E), and A and B may be the same or different, and m represents an integer of 2 or greater.]

[0120] [In formula (II), X represents a hydrogen atom or an organic group having 1 to 20 carbon atoms, and 1 represents an integer of 0 to 3.] <C2> A composition containing the thermosetting resin described in <C1>. <C3> An uncured molded body obtained by molding the thermosetting resin described in <C1> or the composition described in <C2>. <C4> A cured molded body obtained by curing the thermosetting resin described in <C1>, the composition described in <C2>, or the uncured molded body described in <C3>. <C5> A method for producing a thermosetting resin having a benzoxazine ring structure in its main chain, comprising: a step (s1) of reacting a bifunctional phenol compound (A), an aliphatic diamine compound (B), and an aldehyde compound (D); and a step (s3) of reacting a monofunctional phenol compound (E), wherein the aliphatic diamine compound (B) is an aliphatic diamine having a linear alkylene group having 12 carbon atoms.

[0121] The present disclosure is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present disclosure.

[0122] The present invention will be described in detail based on examples, but the present invention is not limited to these examples.

[0123] [Test Methods] The compounds obtained in the following examples and comparative examples were tested for molecular weight, minimum melt viscosity, weight loss rate (%), decomposition onset temperature (°C), glass transition temperature (Tg), thermal decomposition temperature (Td5), tensile modulus, tensile break strength, and tensile break elongation by the following methods.

[0124] (1) Molecular Weight Measurement Using gel permeation chromatography (GPC, manufactured by Shimadzu Corporation), the number average molecular weight (Mn) and weight average molecular weight (Mw) were determined in terms of standard polystyrene.

[0125] (2) Measurement of minimum melt viscosity Measurement was performed using an ARES G2 (manufactured by TA Instruments) with 25 mm parallel plates at a temperature rise rate of 5° C. / min, an angular frequency of 10.0 rad / s (1.6 Hz), and a strain of 0.01%. The minimum melt viscosity means the lowest value of the melt viscosity measured under these conditions.

[0126] (3) Weight loss rate (%), decomposition onset temperature (°C) The weight loss of the uncured resin was evaluated by thermogravimetric analysis (TGA) using a thermogravimetric differential thermal analyzer (STA7200, manufactured by Hitachi High-Tech Science Corporation) at a temperature rise rate of 5°C / min. The weight loss rate (%) was calculated from the weight at room temperature before the start of the measurement and the weight after curing. The decomposition onset temperature was also calculated from the TG inflection point temperature.

[0127] (4) Glass Transition Temperature (Tg) For the uncured film and the cured film, DMA curves were measured using a dynamic viscoelasticity measuring device (DVA-200, manufactured by IT Measurement & Control Co., Ltd.) at a frequency of 1 Hz and a heating rate of 5°C / min. The temperature at the intersection of the tangent to the inflection point of the storage modulus (E') of the obtained DMA curve and the baseline was defined as Tg.

[0128] (5) Thermal Decomposition Temperature (Td5) The 5% weight loss temperature (Td5) of the uncured film and the cured film was evaluated by thermogravimetric analysis (TGA) using a thermogravimetric differential thermal analyzer (STA7200, manufactured by Hitachi High-Tech Science Corporation) at a temperature rise rate of 5°C / min. ２ The values ​​measured by differential thermal analysis (TG-DTA) under air flow were used.

[0129] (6) Tensile Modulus (Modulus), Tensile Break Strength, and Tensile Break Elongation Tensile tests were carried out on uncured films (uncured products in the form of films) and cured films (cured products) using a tensile tester (EZ-SX, manufactured by Shimadzu Corporation). The test temperature was room temperature, the tensile speed was 5 mm / min, and the test specimens were 50 mm long and 3 mm wide.

[0130] (7) Thermoplasticity (toughness upon remolding, thermoplastic remolding ability) The thermoplasticity (toughness upon remolding, thermoplastic remolding ability) of uncured films and partially cured films was evaluated visually. Toughness was evaluated by visually inspecting the film for breakage, cracks, etc. when the film was deformed by hand before and after heating. Remolding ability was evaluated by determining whether the film returned to its pre-deformation state when heated for a predetermined time at a predetermined temperature at which the film was not completely cured.

[0131] (Toughness Evaluation Criteria) ◯: No breaks or cracks were observed in the film. ×: Breaks or cracks were observed in the film.

[0132] (Reformability Evaluation Criteria) ◯: The film returned to its pre-deformation state. ×: The film remained deformed or did not return to its pre-deformation state.

[0133] (8) Flexibility Evaluation (Mandrel Test) The flexibility of the partially cured film and the cured film was evaluated by a mandrel test in accordance with JIS K-5600-5-1:1999. An Elcometer 1500 cylindrical mandrel set was used. The film was hooked onto multiple cylindrical mandrels of different diameters (2 mm to 32 mm), and both ends of the film were pulled. That is, while the film was bent along the curved surface of the cylindrical mandrel, both ends of the film were pulled perpendicular to the longitudinal direction of the cylindrical mandrel. Among the cylindrical mandrels that did not break during this process, the diameter of the smallest cylindrical mandrel was determined and recorded as the bending radius (mm).

[0134] <Production of Resin> The materials used in the production of the resin are shown below.

[0135] (Bifunctional phenol compound (A)) 2,2-bis(4-hydroxyphenyl)propane (bisphenol A, BisA) (manufactured by Tokyo Chemical Industry Co., Ltd. (TCI)) (Aliphatic diamine compound (B)) Hexamethylenediamine (HMD) (manufactured by Tokyo Chemical Industry Co., Ltd. (TCI)) Octamethylenediamine (manufactured by Tokyo Chemical Industry Co., Ltd. (TCI)) Decamethylenediamine (manufactured by Tokyo Chemical Industry Co., Ltd. (TCI)) Dodecamethylenediamine (manufactured by Tokyo Chemical Industry Co., Ltd. (TCI)) ((Poly)oxyalkylenediamine compound (C)) Jeffamine D2000 (manufactured by Hentzman) (Aldehyde compound (D)) Paraformaldehyde (manufactured by Merck) (Monofunctional phenol compound (E)) Phenol (manufactured by Tokyo Chemical Industry Co., Ltd. (TCI)) Example 1 (C8Bz) A benzoxazine-based thermosetting resin (C8Bz) having structural units derived from C8 diamine (octamethylenediamine) was obtained by the method described below.

[0136] 3.1961 g (0.014 mol) of bisphenol A, 3.1654 g (0.020 mol) of octamethylenediamine, 2.5832 g (0.086 mol) of paraformaldehyde, and 1.1316 g (0.012 mol) of phenol were added to chloroform (30 mL) and reacted at 60°C. The reaction was stopped after 4 hours. After cooling the reaction solution to room temperature, separation was performed three times using 60 mL of 0.1 N sodium bicarbonate solution. After washing with sodium sulfate, the reaction solution was dehydrated and filtered. The solvent was removed by heating under reduced pressure in an evaporator, and the mixture was dried under reduced pressure at 40°C in a vacuum oven to obtain a powder of the target compound, benzoxazine resin. Molecular weight measurement by GPC revealed a number average molecular weight (Mn) of 1552 and a weight average molecular weight (Mw) of 4404, calculated in terms of standard polystyrene.

[0137] The resulting benzoxazine resin powder was heated at 100°C for 30 minutes using a hot press to obtain an uncured film. It was then heated and cured in an oven at 200°C for 1 hour, 240°C for 1 hour, and 260°C for 30 minutes to obtain a cured film. The properties of the uncured and cured film are shown in Table 1.

[0138] Example 2 (C10Bz) A benzoxazine-based thermosetting resin (C10Bz) having structural units derived from C10 diamine (decamethylenediamine) was obtained by the method described below.

[0139] Into chloroform (40 mL), 6.3920 g (0.028 mol) of bisphenol A, 6.9328 g (0.040 mol) of decamethylenediamine, 5.1654 g (0.172 mol) of paraformaldehyde, and 2.2586 g (0.024 mol) of phenol were added and reacted at 60 °C. The reaction was stopped after 4 hours. After cooling the reaction solution to room temperature, the solution was separated three times with 80 mL of 0.1 N sodium bicarbonate solution. After washing with sodium sulfate, the reaction solution was dehydrated and filtered. The solvent was removed by heating under reduced pressure in an evaporator, and the mixture was dried under reduced pressure at 40 °C in a vacuum oven to obtain a powder of the target compound, benzoxazine resin. Molecular weight measurement by GPC revealed a number average molecular weight (Mn) of 2097 and a weight average molecular weight (Mw) of 4582, calculated in terms of standard polystyrene.

[0140] The resulting benzoxazine resin powder was heated at 100°C for 30 minutes using a hot press to obtain an uncured film. It was then heated and cured in an oven at 200°C for 1 hour, 240°C for 1 hour, and 260°C for 30 minutes to obtain a cured film. The properties of the uncured and cured film are shown in Table 1.

[0141] Example 3 (C12Bz) A benzoxazine-based thermosetting resin (C12Bz) having a structural unit derived from C12 diamine (dodecamethylenediamine) was obtained by the method described below.

[0142] Into a mixed solvent of toluene (57.96 mL) and isobutanol (10.23 mL), 6.2324 g (0.027 mol) of bisphenol A, 6.0012 g (0.030 mol) of dodecamethylenediamine, 5.4051 g (0.180 mol) of paraformaldehyde, and 0.7678 g (0.008 mol) of phenol were added and reacted at 100°C. The reaction was stopped after 4 hours. After the reaction solution was cooled to room temperature, separation was performed four times with 500 mL of 0.03 N aqueous sodium hydroxide solution. After washing with sodium sulfate, the reaction solution was dehydrated and filtered. The solvent was removed by heating under reduced pressure using an evaporator, and the mixture was dried under reduced pressure at 60°C in a vacuum oven to obtain the target compound, a benzoxazine resin powder. Measurement of the molecular weight by GPC revealed that the number average molecular weight (Mn) was 2,831 and the weight average molecular weight (Mw) was 5,509, calculated in terms of standard polystyrene.

[0143] The resulting benzoxazine resin powder was heated at 100°C for 30 minutes using a hot press to obtain an uncured film. It was then heated and cured in an oven at 200°C for 1 hour, 240°C for 1 hour, and 260°C for 30 minutes to obtain a cured film. The properties of the uncured and cured film are shown in Table 1.

[0144] Example 4 (JD11): Bisphenol A (4.5669 g, 0.02 mol), hexamethylenediamine (1.1631 g, 0.01 mol), Jeffamine D2000 (20.0191 g, 0.01 mol), and paraformaldehyde (2.5868 g, 0.086 mol) were added to chloroform (40 mL) and reacted at 60°C. The reaction was stopped after 5 hours. After cooling the reaction solution to room temperature, separation was performed three times using 60 mL of 0.1 N sodium bicarbonate solution. After washing with sodium sulfate, the reaction solution was dehydrated and filtered. The solvent was removed using an evaporator under reduced pressure and then dried under reduced pressure at 40°C in a vacuum oven to obtain the target compound, a benzoxazine resin powder. Measurement of the molecular weight by GPC revealed that the number average molecular weight (Mn) was 6,061 and the weight average molecular weight (Mw) was 17,568, calculated in terms of standard polystyrene.

[0145] The obtained benzoxazine resin powder was heated and pressed using a hot press at 160°C for 30 minutes at 10 MPa to obtain an uncured film-like molded article (uncured film). The obtained uncured film was heat-cured in a convection oven at 210°C for 2 hours to obtain a cured film-like molded article (cured film). The properties of the uncured film and the cured film are shown in Table 1. Since the molar ratio of Jeffamine D2000 to hexamethylenediamine used was 1:1, the benzoxazine resin obtained in Example 4 is also referred to as JD11.

[0146] Example 5 (JD13): Bisphenol A (4.5665 g, 0.02 mol), hexamethylenediamine (1.7444 g, 0.015 mol), Jeffamine D2000 (10.0161 g, 0.005 mol), and paraformaldehyde (2.5857 g, 0.086 mol) were added to chloroform (40 mL) and reacted at 60°C. The reaction was stopped after 5 hours. After cooling the reaction solution to room temperature, separation was performed three times using 60 mL of 0.1 N sodium bicarbonate solution. After washing with sodium sulfate, the reaction solution was dehydrated and filtered. The solvent was removed using an evaporator under reduced pressure and then dried under reduced pressure at 40°C in a vacuum oven to obtain the target compound, a benzoxazine resin powder. Measurement of the molecular weight by GPC revealed that the number average molecular weight (Mn) was 5,939 and the weight average molecular weight (Mw) was 17,377, calculated in terms of standard polystyrene.

[0147] The obtained benzoxazine resin powder was heated and pressed at 100°C or 140°C for 30 minutes under 10 MPa using a hot press to obtain an uncured film. The obtained uncured film was then heat-cured in a convection oven at 210°C for 3 hours to obtain a cured film. The properties of the uncured film and the cured film are shown in Table 1. Note that the benzoxazine resin obtained in Example 5 is also referred to as JD13 because the molar ratio of Jeffamine D2000 to hexamethylenediamine used was 1:3.

[0148] Example 6 (JD19): Bisphenol A (4.5666 g, 0.02 mol), hexamethylenediamine (2.0923 g, 0.018 mol), Jeffamine D2000 (4.0000 g, 0.002 mol), and paraformaldehyde (2.5840 g, 0.086 mol) were added to chloroform (40 mL) and reacted at 60°C. The reaction was stopped after 5 hours. After cooling the reaction solution to room temperature, separation was performed three times using 60 mL of 0.1 N sodium bicarbonate solution. After washing with sodium sulfate, the reaction solution was dehydrated and filtered. The solvent was removed using an evaporator under reduced pressure and then dried under reduced pressure at 40°C in a vacuum oven to obtain the target compound, a benzoxazine resin powder. Measurement of the molecular weight by GPC revealed that the number average molecular weight (Mn) was 6,063 and the weight average molecular weight (Mw) was 17,414, calculated in terms of standard polystyrene.

[0149] The obtained benzoxazine resin powder was heated and pressed at 100°C for 30 minutes under 10 MPa using a hot press to obtain an uncured film. The obtained uncured film was then heat-cured in a convection oven at 220°C for 2 hours to obtain a cured film. The properties of the uncured film and the cured film are shown in Table 1. Note that the benzoxazine resin obtained in Example 6 is also referred to as JD19 because the molar ratio of Jeffamine D2000 to hexamethylenediamine used was 1:9.

[0150] Comparative Example 1 (C6Bz1) 4.1505 g (0.018 mol) of bisphenol A, 2.3243 g (0.020 mol) of hexamethylenediamine, 3.6053 g (0.120 mol) of paraformaldehyde, and 0.5149 g (0.005 mol) of phenol were added to a mixed solvent of toluene (38.6 mL) and isobutanol (6.8 mL), and the mixture was allowed to react at 90 ° C. The reaction was stopped after 5 hours. The reaction solution was added to 800 mL of methanol to precipitate the target compound. The target compound was then separated by filtration and dried under reduced pressure at 45 ° C in a vacuum oven to obtain the target compound. Measurement of the molecular weight by GPC revealed that the number average molecular weight (Mn) was 2733 and the weight average molecular weight (Mw) was 7146, calculated in terms of standard polystyrene.

[0151] The resulting benzoxazine resin powder was heated at 120°C for 40 minutes using a hot press, then heated to 160°C and heated and pressed at 10 MPa for 30 minutes to obtain an uncured film. The resulting film was then heated and cured in an oven at 200°C for 1 hour, 240°C for 1 hour, and 260°C for 30 minutes to obtain a cured film. The properties of the uncured and cured film are shown in Table 1.

[0152] Comparative Example 2 (C6Bz2) 9.5889 g (0.042 mol) of bisphenol A, 6.9718 g (0.060 mol) of hexamethylenediamine, 7.7485 g (0.258 mol) of paraformaldehyde, and 3.3887 g (0.036 mol) of phenol were added to chloroform (150 mL) and reacted at 60°C. The reaction was stopped after 5 hours. The reaction solution was cooled to room temperature and then separated three times with 300 mL of 0.1 N sodium bicarbonate solution. After washing with sodium sulfate, the reaction solution was dehydrated and filtered. The solvent was removed by heating under reduced pressure in an evaporator, and the target compound was obtained by drying under reduced pressure at 40°C in a vacuum oven. Molecular weight measurement by GPC revealed that the number average molecular weight (Mn) was 1884 and the weight average molecular weight (Mw) was 3847, calculated as standard polystyrene.

[0153] This benzoxazine powder was heated in a hot press at 120°C for 40 minutes, then heated to 160°C, and heated and pressed at 10 MPa for 30 minutes to obtain an uncured film. It was then heated and cured in an oven at 200°C for 1 hour, 240°C for 1 hour, and 260°C for 30 minutes to obtain a cured film. The properties of the uncured and cured film are shown in Table 1.

[0154] In Examples 1 to 6 using the diamine compound according to one embodiment of the present invention, film-like molded articles were obtained by hot pressing, demonstrating that thermoplastic molding before curing is possible. Furthermore, Table 1 shows that, in terms of the thermal and mechanical properties of the uncured molded articles obtained in Examples 1 to 6, compared to Comparative Examples 1 and 2, the Tg was lower, the tensile modulus and tensile strength at break were smaller, and the tensile elongation at break was greater. Therefore, it was revealed that, before curing, Examples 1 to 6 exhibited superior flexibility compared to Comparative Examples 1 and 2.

[0155] After curing, Examples 1 to 3 had the same Tg and excellent heat resistance, despite the alkyl chain elongation, compared to Comparative Example 1 and Comparative Example 2. Furthermore, Example 1 had the same tensile modulus, tensile strength at break, and tensile elongation at break, compared to Comparative Example 1 and Comparative Example 2, indicating excellent hardness. On the other hand, Examples 2 and 3 had smaller tensile modulus and tensile strength at break but larger tensile elongation at break, indicating excellent toughness, compared to Comparative Example 1 and Comparative Example 2.

[0156] JD11 of Example 4 was fully cured at 210°C for 2 hours, with a weight loss rate of 1.0%. JD13 of Example 5 was fully cured at 210°C for 3 hours, with a weight loss rate of 3.0%. JD19 of Example 6 was fully cured at 220°C for 2 hours, with a weight loss rate of 2.0%. In contrast, C6Bz2 of Comparative Example 2 required heating at 240°C for 1 hour and then at 260°C for 30 minutes until the resin was fully cured, with a weight loss rate of 9.0%. These results demonstrate that the use of Jeffamine D2000, the (poly)oxyalkylenediamine compound (C), and hexamethylenediamine, the aliphatic diamine compound (B), reduces the weight loss rate of the thermosetting resin, i.e., the decomposition rate.

[0157] Furthermore, the decomposition onset temperatures of the uncured films or partially cured films of Examples 4 to 6 were 8 to 10°C higher than the decomposition onset temperature of the uncured film of Comparative Example 2. These results demonstrate that the use of Jeffamine D2000 as the (poly)oxyalkylenediamine compound (C) and hexamethylenediamine as the aliphatic diamine compound (B) increases the decomposition onset temperature.

[0158] Furthermore, the tensile elongation at break of Examples 4 to 6, for all of the uncured film, partially cured film, and cured film, was significantly greater than the tensile elongation at break of Comparative Examples 1 and 2. These results demonstrate that the use of Jeffamine D2000 as the (poly)oxyalkylenediamine compound (C) and hexamethylenediamine as the aliphatic diamine compound (B) increases the toughness before and after curing.

[0159] Comparative Example 1 and Comparative Example 2 differ in the solvent used when producing the thermosetting resin. Comparative Example 1 uses a mixed solvent of a non-halogenated hydrocarbon solvent and an aliphatic alcohol solvent, while Comparative Example 2 uses a halogenated solvent alone. Comparing the mechanical properties of Comparative Example 1 and Comparative Example 2 from Table 1, no significant differences were observed either before or after curing. This indicates that the difference in solvent has little effect on the mechanical properties before and after curing.

[0160] <Remoldability Evaluation> [Example 7] A release PET spacer with a hole (50 μm thick, 10 cm square) in the center was placed on release PET (50 μm thick). The resin prepared in Example 4 was placed in the hole, and release PET was then layered on top of that. This layered product was sandwiched between stainless steel plates and heated in a press molding machine at 160°C for 5 minutes, followed by press molding at a pressure of 10 MPa for 5 minutes to obtain a film with a thickness of 0.05 mm. The obtained film was fixed to a frame, and the edges of the film were cut and removed along the outer edge of the frame with a cutter to obtain a self-supporting, flexible film. The film was then crushed by hand and rolled into a small ball, but no breakage was observed. The film was again placed in the frame, release PET was layered on top, and the resulting film was sandwiched between stainless steel plates. The resulting film was heated in a press molding machine at 160°C for 5 minutes, followed by press molding at a pressure of 10 MPa for 5 minutes, and the 0.05 mm thick film was completely restored.

[0161] As described above, the uncured or partially cured films obtained from the resin prepared in Example 4 have excellent toughness, as they do not break or crack even when rolled or deformed into any shape. Furthermore, it can be seen that the uncured or partially cured films of this example simultaneously possess thermoplastic remoldability and toughness during remolding.

[0162] Example 8 A release PET spacer with a hole (50 μm thick, 10 cm square) in the center was placed on release PET (50 μm thick). The resin prepared in Example 5 was placed in the hole, and release PET was then layered on top of that. This layered product was sandwiched between stainless steel plates and heated in a press molding machine at 140°C for 5 minutes, followed by press molding at a pressure of 10 MPa for 5 minutes to obtain a film with a thickness of 0.05 mm. The obtained film was fixed to a frame, and the edges of the film were cut and removed along the outer edge of the frame with a cutter to obtain a self-supporting, flexible film. The film was then crushed by hand and rolled into a small ball, but no breakage was observed. The film was then placed back on the frame, release PET was layered on top, and the resulting film was sandwiched between stainless steel plates. The resulting film was heated in a press molding machine at 140°C for 5 minutes, followed by press molding at a pressure of 10 MPa for 5 minutes, resulting in a completely restored film to its original thickness of 0.05 mm.

[0163] Thus, it can be seen that the uncured or partially cured film obtained from the resin prepared in Example 5 also possesses not only thermoplastic formability and toughness during molding, but also thermoplastic remoldability and toughness during remolding.

[0164] Example 9 A release PET spacer with a hole (50 μm thick, 10 cm square) in the center was placed on release PET (50 μm thick). The resin prepared in Example 6 was placed in the hole, and release PET was then layered on top of that. This layered product was sandwiched between stainless steel plates and heated in a press molding machine at 100°C for 5 minutes, followed by press molding at a pressure of 10 MPa for 5 minutes to obtain a 0.05 mm thick film. The obtained film was fixed to a frame, and the edges of the film were cut and removed along the outer edge of the frame with a cutter to obtain a self-supporting, flexible film. The film was then crushed by hand and rolled into a small ball, but no breakage was observed. The film was then placed back on the frame, release PET was layered on top, and the resulting film was sandwiched between stainless steel plates. The resulting film was heated in a press molding machine at 100°C for 5 minutes, followed by press molding at a pressure of 10 MPa for 5 minutes, resulting in a completely restored 0.05 mm thick film.

[0165] Thus, it can be seen that the uncured or partially cured film obtained from the resin prepared in Example 6 also possesses not only thermoplastic formability and toughness during molding, but also thermoplastic remoldability and toughness during remolding.

[0166] Comparative Example 3 A release PET spacer with a hole (50 μm thick, 10 cm square) in the center was placed on release PET (50 μm thick). The resin prepared in Comparative Example 2 was placed in the hole, and release PET was then layered on top of that. This layered product was sandwiched between stainless steel plates and heated in a press molding machine at 100°C for 5 minutes, followed by press molding at a pressure of 10 MPa for 5 minutes to obtain a 0.05 mm thick film. The obtained film was fixed to a frame, and the edges of the film were cut and removed along the outer edge of the frame with a cutter to obtain a self-supporting, brittle film. The film was then crushed by hand into small balls, resulting in the film breaking into pieces. The shattered film pieces were placed back on the frame, release PET was layered on top, and the resulting product was sandwiched between stainless steel plates. The resulting product was heated in a press molding machine at 100°C for 5 minutes, followed by press molding at a pressure of 10 MPa for 5 minutes, resulting in the 0.05 mm thick film being completely restored.

[0167] Comparative Example 4: A 0.05 mm thick film was obtained by the same method as in Comparative Example 3, except that the film was heated in a press molding machine at 160°C for 5 minutes and then press molded at a pressure of 10 MPa for 5 minutes. The obtained film was fixed to a frame, and the edges of the film were cut and removed with a cutter along the outer edge of the frame to obtain a self-supporting, flexible film. The film was then crushed by hand and rolled into a small ball, but no breakage was observed. The film was placed back on the frame, a release PET film was placed on top, and the film was sandwiched between stainless steel plates. The film was heated in a press molding machine at 160°C for 5 minutes and then press molded at a pressure of 10 MPa for 5 minutes, but the 0.05 mm thick film did not completely recover.

[0168] <Flexibility Evaluation (Mandrel Test)> [Example 10] The resin prepared in Example 6 was heated and pressurized using a hot press under the following conditions: (i) 100°C for 30 minutes at 10 MPa to obtain a film (degree of cure: 5%). The film formed in (i) was further heated in a convection oven under the following conditions without pressure: (ii) 140°C for 2 hours (degree of cure: 22%), (iii) 180°C for 1 hour (degree of cure: 55%), and (iv) 220°C for 2 hours (degree of cure: 100%) to obtain a film (degree of cure is listed after each condition). In this way, four films with different degrees of cure were prepared. Each film had a thickness of 0.125 mm.

[0169] The degree of cure of each film was calculated from the ratio of the area of ​​the curing exothermic peak obtained by DSC of the uncured resin and the film after heating. Using an Elcometer 1500 cylindrical mandrel set, the film was hooked onto cylindrical mandrels of different diameters (2 mm to 32 mm), and the film was pulled at both ends. The minimum diameter at which the film did not break was taken as the bending radius (mm) to evaluate flexibility. If the film did not break even when using a cylindrical mandrel with the minimum diameter (2 mm), the film was bent at an angle of 180 degrees (resulting in a pseudo-zero diameter) and evaluated for breakage. The results are shown in Table 3.

[0170] Example 11 The resin prepared in Example 4 was heated and pressed at 160°C and 10 MPa for 30 minutes using a hot press to prepare a film with a thickness of 0.125 mm. The obtained film was subjected to a mandrel test similar to that in Example 10 to evaluate its flexibility. The results are shown in Table 3.

[0171] Example 12 The resin prepared in Example 5 was heated and pressed at 140°C and 10 MPa for 30 minutes using a hot press to prepare a film with a thickness of 0.125 mm. The obtained film was subjected to a mandrel test similar to that in Example 10 to evaluate its flexibility. The results are shown in Table 3.

[0172] Comparative Example 5: The resin prepared in Comparative Example 2 was heated and pressed at 100°C and 10 MPa for 30 minutes using a hot press to obtain a film having a thickness of 0.125 mm. The obtained film was subjected to a mandrel test similar to that in Example 10, but this film was not self-supporting and therefore could not be measured.

[0173] Comparative Example 6 The resin prepared in Comparative Example 2 was heated and pressed at 160°C and 10 MPa for 30 minutes using a hot press to obtain a film with a thickness of 0.125 mm. The obtained film was subjected to a mandrel test similar to that in Example 10 to evaluate its flexibility. The results are shown in Table 3.

[0174] Thus, the uncured or partially cured films obtained from the resins of Examples 4 and 5 exhibited excellent toughness, as evidenced by the absence of breakage or cracking in the flexibility test (mandrel test) using a 2 mm diameter cylinder. Furthermore, the absence of breakage or cracking in the 180-degree bending test, which did not use a cylinder, also demonstrated excellent toughness.

[0175] Similarly, films with a degree of cure of 5% to 100% obtained from the resin of Example 6 showed no tearing or cracking in a flexibility test (mandrel test) using a 2 mm diameter cylinder, indicating excellent toughness. Furthermore, partially cured films with a degree of cure of 5% to 55% showed no tearing or cracking in a 180-degree bending test without a cylinder, indicating excellent toughness.

[0176] <Changes in Dynamic Viscoelasticity (DMA) Curve with Degree of Cure> [Example 13] The above-mentioned "(4) Glass Transition Temperature (Tg)" DMA test was performed on films prepared under the conditions (i) to (iv) of Example 10, as well as films cured at 120°C for 0.5 hours (degree of cure: 11%) and 140°C for 1 hour (degree of cure: 16%), and the changes in the DMA curve were measured. The horizontal axis represents temperature (°C) and the vertical axis represents storage modulus (Pa). The measurement results are shown in Figure 1.

[0177] Increasing the degree of cure resulted in a shift in Tg to higher temperatures as well as an increase in modulus in the rubbery plateau.

[0178] In addition, for films with a degree of cure ranging from 5% to 55%, ６ ~10 ７ A rubber-like plateau region on the order of Pa·s is observed, and heating at a temperature within this region makes it easy to remold the resin, indicating that the degree of cure is preferably in the range of 5% to 55%.

[0179] <Production of Carbon Fiber Composite Material (CFRP) and Evaluation thereof> (1) Amount of Bleed-Out (Extrusion) Resin (% by weight) The weight of the resin that extruded from the CFRP after curing and heating was measured, and the ratio of this weight to the total amount of resin impregnated in the carbon fiber before curing was calculated.

[0180] (2) Voids (90-degree fiber) A 1 cm square was cut from the center of a CFRP plate using a diamond cutter and embedded in epoxy resin. Next, a cross section containing the CFRP (a cross section perpendicular to the fiber extension direction) was exposed using the diamond cutter, and the cross section was polished using a polishing machine (MINITECH223, manufactured by Presi). The cross section was then observed using a digital microscope (VHX-200, manufactured by Keyence Corporation) to evaluate the presence or absence of voids in the 90-degree fiber direction. Here, "voids in the 90-degree fiber direction" refers to voids present in the fibers (voids surrounded by fibers) in a cross section perpendicular to the fiber extension direction.

[0181] (3) Voids (Resin) The presence or absence of voids in the cross section where only resin was present was evaluated using the same method as in (2) above.

[0182] (4) Discoloration of Resin Using the same method as in (2) above, the presence or absence of discoloration in the cross section where only the resin was present was evaluated.

[0183] (5) Storage Modulus (E') The storage modulus E' of the CFRP was determined using a dynamic viscoelasticity measuring device (RSA-3, manufactured by TA Instruments) at a measurement frequency of 1 Hz and a measurement temperature of 50°C.

[0184] (6) Glass Transition Temperature (Tg) The glass transition temperature Tg of the CFRP was determined using a dynamic viscoelasticity measuring device (RSA-3, manufactured by TA Instruments).

[0185] (1. Film Production Method) [Example 14] A release PET spacer with a hole (50 µm thick, 8 cm square or 10 cm square) in the center was placed on release PET (50 µm thick), the resin produced in Example 6 was placed in the hole, and release PET was then placed on top of that. This laminate was sandwiched between stainless steel plates and heated in a press molding machine at 60°C for 5 minutes, and then press-molded at a pressure of 10 MPa for 10 minutes to obtain a film with a thickness of 0.05 mm.

[0186] (2. Method for Producing Prepreg) The types of carbon fiber plain weave materials used to produce the prepreg are as follows: PAN-based carbon fiber manufactured by Mitsubishi Chemical Corporation (trade name: TR3110 M, fiber basis weight: 200 g / m ２ , Density: 1.79g / cm ３ ) PAN-based carbon fiber manufactured by Toray Industries, Inc. (product name: CO6343B, fiber basis weight: 198 g / m ２ , Density: 1.76g / cm ３ The PAN-based carbon fiber manufactured by Toray Industries, Inc. was heated in a convection oven at 300° C. for 1.5 hours to remove the sizing agent.

[0187] Example 15 The films prepared in Example 14 were layered on both sides of a carbon fiber plain weave material (TR3110 M), sandwiched between stainless steel plates, heated at 60°C for 5 minutes in a press molding machine, and then press-molded at a pressure of 1 MPa for 10 minutes to obtain a prepreg with a thickness of 0.2 to 0.3 mm. An 8 cm square film was layered on the front of the carbon fiber plain weave material, and a 10 cm square film was layered on the back.

[0188] Example 16 A prepreg having a thickness of 0.2 to 0.3 mm was obtained in the same manner as in Example 12, except that the type of carbon fiber plain weave material was CO6343B.

[0189] (3. CFRP Production Method) [Example 17] The prepregs produced in Example 15 were laminated to form 10 layers. The resulting laminated prepreg was sandwiched between two PI films as release films. The sides (thickness portions) of the laminated prepreg were exposed from the PI films. The laminated prepreg sandwiched between the PI films was further sandwiched between stainless steel plates and cured in a press molding machine by (1) pressing at 60°C and 1 MPa for 10 minutes, (2) subsequently heating to 100°C and pressing at 1 MPa for 20 minutes, and (3) subsequently heating to 220°C and pressing at 1 MPa for 2 hours. This resulted in a plate-shaped CFRP with a thickness of approximately 2 mm. The results are shown in Table 4.

[0190] Example 18: The prepregs prepared in Example 16 were laminated to form five layers. The resulting laminated prepreg was covered with two 8 cm long and 25 cm wide PI films as release films. The covered laminated prepreg was then sandwiched between stainless steel plates and cured in a press molding machine by (1) pressing at 60°C and 1 MPa for 10 minutes, (2) subsequently heating to 100°C and pressing at 1 MPa for 20 minutes, and (3) subsequently heating to 220°C and pressing at 1 MPa for 2 hours. This resulted in a plate-shaped CFRP approximately 1 mm thick. The results are shown in Table 4.

[0191] Example 19: The prepregs prepared in Example 16 were laminated to form five layers. The resulting laminated prepreg was covered with two 8 cm long and 25 cm wide PI films as release films. The covered laminated prepreg was then sandwiched between stainless steel plates and pressed in a press molding machine (1) at 60°C and 1 MPa for 10 minutes, (2) after which the temperature was raised to 100°C and pressed at 1 MPa for 20 minutes, and then removed. The covered laminated prepreg was then cured by (3) heating at 220°C for 2 hours in a vacuum oven. This resulted in a plate-shaped CFRP with a thickness of approximately 1 mm. The results are shown in Table 4.

[0192] Example 20: The prepregs prepared in Example 16 were laminated to form five layers. The resulting laminated prepreg was covered with two 8 cm long and 25 cm wide PI films as release films. The covered laminated prepreg was then sandwiched between stainless steel plates and placed in a vacuum press molding machine. (1) After heating at 100°C for 8 minutes (at atmospheric pressure), (2) vacuum-pressed at 2 MPa for 22 minutes and then removed. (3) The temperature was then raised to 220°C and vacuum-pressed at 2 MPa for 2 hours to cure the prepreg. This resulted in a plate-shaped CFRP with a thickness of approximately 1 mm. The results are shown in Table 4.

[0193] Example 21: The prepregs prepared in Example 16 were laminated to form five layers. The resulting laminated prepreg was covered with two 8 cm long and 25 cm wide PI films as release films. The covered laminated prepreg was then sandwiched between stainless steel plates and cured in a vacuum press molding machine by (1) heating at 100°C for 7 minutes (atmospheric pressure), (2) vacuum pressing at 2 MPa for 23 minutes, and (3) increasing the temperature to 220°C and vacuum pressing at 2 MPa for 2 hours. This resulted in a CFRP plate with a thickness of approximately 1 mm. The results are shown in Table 4.

[0194] As can be seen from Table 4, the thermosetting resin using Jeffamine D2000, which is the (poly)oxyalkylenediamine compound (C), and hexamethylenediamine, which is the aliphatic diamine compound (B), can be suitably used for CFRP.

[0195] Examples 19 to 21 demonstrate that removing the sizing agent is preferable from the perspective of preventing discoloration of the resin and voids between the resins. Furthermore, in Examples 18 to 21, bleed-out was reduced by covering with a PI film. It is presumed that the use of a vacuum oven or vacuum press molding machine in Examples 19 to 21 contributed to the suppression of voids between the resins. It is presumed that the use of a press molding machine or vacuum press molding machine can suppress voids between the fibers. However, as in Examples 17, 18, and 21, by heating the prepreg without removing it from the press molding machine or vacuum press molding machine, voids between the fibers were further suppressed.

[0196] The present disclosure can be utilized in fields using thermosetting resins.

Claims

1. A thermosetting resin having a benzoxazine ring structure in the main chain, represented by general formula (I). 【Chemical 1】 [In general formula (I), Ar １ and Ar ２ may be the same or different and each represent a tetravalent aromatic group derived from the bifunctional phenol compound (A), n represents an integer of 0 or more, R １ represents a linear alkylene group having 8 to 12 carbon atoms derived from the aliphatic diamine compound (B) when n=0, and represents a linear alkylene group having 6 to 12 carbon atoms derived from the aliphatic diamine compound (B) when n=1 or more, R ２ represents a (poly)oxyalkylene group derived from the (poly)oxyalkylenediamine compound (C), When n=0, at least one of the two terminals of the main chain is a group derived from the monofunctional phenol compound (E) and represented by the following general formula (II), and the two terminals may be the same or different: m represents an integer of 2 or more when n=0, and represents an integer of 1 or more when n=1 or more; The repeating unit represented by m and the repeating unit represented by n are randomly repeated, block repeated, or alternately copolymerized; The ratio of m to n is n / m=1 / 0.1 to 1 / 100. 【Chemistry 2】 [In the general formula (II), X represents a hydrogen atom or an organic group having 1 to 20 carbon atoms; and l represents an integer of 0 to 3.

2. The bifunctional phenol compound (A) is 2,2-bis(4-hydroxyphenyl)propane, 1,1-bis(4-hydroxyphenyl)-1-phenylethane, 2,2-bis(4-hydroxyphenyl)hexafluoropropane, 2,2-bis(4-hydroxyphenyl)butane, bis(4-hydroxyphenyl)diphenylmethane, 2,2-bis(3-methyl-4-hydroxyphenyl)propane, bis(4-hydroxyphenyl)-2,2-dichloroethylene, 1,1-bis(4-hydroxyphenyl)ethane, bis(4-hydroxyphenyl)methane, 2,2-bis(4-hydroxy-3 1,3-bis(2-(4-hydroxyphenyl)-2-propyl)propane, 1,3-bis(2-(4-hydroxyphenyl)-2-propyl)benzene, bis(4-hydroxyphenyl)sulfone, 1,4-bis(2-(4-hydroxyphenyl)-2-propyl)benzene, 5,5'-(1-methylethylidene)-bis[1,1'-(bisphenyl)-2-ol]propane, 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane, 1,1-bis(4-hydroxyphenyl)cyclohexane. The thermosetting resin according to claim 1, which is at least one bifunctional phenol compound selected from the group consisting of 1,3-bis(2-(4-hydroxyphenyl)-2-propyl)propane, 1,3-bis(2-(4-hydroxyphenyl)-2-propyl)benzene, 5,5'-(1-methylethylidene)-bis[1,1'-(bisphenyl)-2-ol]propane, 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane, and 1,1-bis(4-hydroxyphenyl)cyclohexane.

3. The thermosetting resin according to claim 1 , wherein the (poly)oxyalkylenediamine compound (C) has a (poly)oxyethylene group and / or a (poly)oxypropylene group.

4. A composition comprising the thermosetting resin according to any one of claims 1 to 3.

5. An uncured molded article obtained by molding the thermosetting resin according to any one of claims 1 to 3.

6. 6. The uncured molded article according to claim 5, which has a bending radius of 2 mm or less in a mandrel test in accordance with JIS K-5600-5-1:1999.

7. A partially cured molded article obtained by partially curing the thermosetting resin according to any one of claims 1 to 3, and having a degree of cure of 1% to 99%.

8. 8. The partially cured molded article according to claim 7, which has a bending radius of 2 mm or less in a mandrel test in accordance with JIS K-5600-5-1:1999.

9. A cured molded article obtained by curing the thermosetting resin according to any one of claims 1 to 3.

10. 10. The cured molded article according to claim 9, which has a bending radius of 2 mm or less in a mandrel test in accordance with JIS K-5600-5-1:1999.

11. A method for producing a thermosetting resin having a benzoxazine ring structure in a main chain, comprising: A step (s1) of reacting a bifunctional phenol compound (A), an aliphatic diamine compound (B), and an aldehyde compound (D); optionally, a step (s2) of reacting a bifunctional phenol compound (A), a (poly)oxyalkylenediamine compound (C), and an aldehyde compound (D); and optionally a step (s3) of reacting a monofunctional phenolic compound (E), If step (s2) is not included, step (s3) is included. When the step (s2) is included, the aliphatic diamine compound (B) is an aliphatic diamine having a linear alkylene group having 6 to 12 carbon atoms, and when the step (s2) is not included, the aliphatic diamine compound (B) is an aliphatic diamine having a linear alkylene group having 8 to 12 carbon atoms; the (poly)oxyalkylenediamine compound (C) has a (poly)oxyethylene group and / or a (poly)oxypropylene group, a molar ratio of the aliphatic diamine compound (B) to the (poly)oxyalkylenediamine compound (C) is (poly)oxyalkylenediamine compound (C) / aliphatic diamine compound (B)=1 / 0.1 to 1 / 100.

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