JP2022053324A - Benzoxazine-based thermosetting resin, and method for producing the same - Google Patents

Abstract

To provide a benzoxazine-based thermosetting resin which is excellent in stability in a solution state and mechanical properties before and after curing, and a method for producing the same.SOLUTION: (1) A thermosetting resin has a benzoxazine ring structure, and a divalent linear alkylene group that is derived from an aliphatic diamine compound and has 6 carbon atoms in a main chain. (2) A method for producing the thermosetting resin includes a step of reacting a bifunctional phenol compound, a diamine compound and an aldehyde compound, and a step of reacting a monofunctional phenol compound.SELECTED DRAWING: None

Description

The present invention relates to a benzoxazine-based thermosetting resin having excellent stability in a solution state and mechanical properties before and after curing, and a method for producing the same.

It is known that a benzoxazine compound is cured without generating volatile components by ring-opening polymerization and reaction of the benzoxazine ring by heat or the like. Therefore, a thermosetting resin containing a low molecular weight compound / polymer having a benzoxazine structure as a main component (hereinafter referred to as a benzoxazine-based thermosetting resin) has heat resistance, water resistance, chemical resistance, mechanical strength, and In addition to the basic characteristics of thermosetting resins such as long-term reliability, they have various advantages such as low dielectric constant and low curing shrinkage, and are attracting attention. Here, the low molecular weight compound having a benzoxazine structure is easy to produce, but has characteristics such as being brittle in a solid state before curing and being difficult to handle, and is also a polymer having a benzoxazine structure (hereinafter, benzo). Oxazine polymers) are easy to handle in a solid state before curing, but are difficult to manufacture, so they are used properly according to their characteristics.

Here, it is also known that the benzoxazine polymer is inferior in stability (storage stability) in a solution state dissolved in a solvent and easily gels. Therefore, in the method for producing such a thermosetting resin, the production method in which the monofunctional phenol compound is added in the reaction step of reacting the bifunctional phenol compound, the diamine compound, and the aldehyde compound has improved storage stability. It has been proposed as an excellent method (Patent Document 1). In such a method, by adding a monofunctional phenol compound, it is possible to seal the reactive end and prevent gelation, but on the other hand, it inhibits the polymerization reaction in which the molecular weight grows, so that the benzo having a high molecular weight is used. It has been clarified by the studies of the present inventors that it is difficult to obtain oxadin.

Japanese Unexamined Patent Publication No. 2008-291070

The present invention has been made in view of such circumstances, and an object thereof is to provide a benzoxazine-based thermosetting resin having excellent stability in a solution state and mechanical properties before and after curing, and a method for producing the same. It is to be.

The configuration of the present invention is as follows.
1. 1. A thermosetting resin having a benzoxazine ring structure in a main chain represented by the general formula (I).

[In formula (I)
Ar1 represents a tetravalent aromatic group derived from the bifunctional phenol compound (A).
R1 represents a divalent linear alkylene group having 6 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 (D), and A and B may be the same or different.
n represents an integer of 2 or more,
The weight average molecular weight (Mw) measured by GPC is 10,000 or more. ]

[In formula (II)
X represents a hydrogen atom or an organic group having 1 to 20 carbon atoms.
l represents an integer of 0 to 3. ]
2. 2. The composition containing the thermosetting resin of 1 above.
3. 3. An uncured molded product obtained by molding the thermosetting resin of 1 above or the composition of 2 above.
4. A cured molded product obtained by curing the thermosetting resin (1), the composition (2), or the uncured molded product (3).
5. A method for producing a thermosetting resin having a benzoxazine ring structure in the main chain.
The step (s1) of reacting the bifunctional phenol compound (A), the diamine compound (B), and the aldehyde compound (C),
Further, the step (s2) of reacting the monofunctional phenol compound (D) is included.
The step (s1) and the step (s2) may be simultaneous, or the step (s1) may be first and the step (s2) may be later.
The diamine compound (B) is a linear aliphatic diamine having 6 carbon atoms.
Step (s1) and step (s2) are steps in a mixed solvent containing a solvent (L1) and a solvent (L2).
The solvent (L1) is a non-halogen hydrocarbon solvent, and is
The solvent (L2) is an aliphatic alcohol-based solvent.
A method for manufacturing a thermosetting resin.
6. The solvent (L1) is toluene and / or xylene,
The solvent (L2) is at least one selected from the group consisting of methanol, ethanol, propanol and butanol (including structural isomers).
The method for producing a thermosetting resin according to 5 above.
7. The volume ratio of the solvent (L1) to the solvent (L2) is (L1) / (L2) = 50/50 to 80/20.
The method for producing a thermosetting resin according to 5 or 6 above.

According to the present invention, there is provided a benzoxazine-based thermosetting resin which is stable in a solution state and has excellent mechanical properties before and after curing.

Next, an embodiment of the present invention will be described. The following embodiments are examples for explaining the present invention, and the present invention is not intended to be limited to this embodiment. The present invention can be carried out in various forms as long as it does not deviate from the gist thereof.

In the present specification, when a certain parameter takes a value X to a value Y, it means that the parameter is X or more and Y or less.

[Thermosetting resin]
The thermosetting resin of the present invention has a benzoxazine structure represented by the following general formula (I).

[In formula (I)
Ar1 represents a tetravalent aromatic group derived from the bifunctional phenol compound (A).
R1 represents a divalent linear alkylene group having 6 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 (D), and A and B may be the same or different.
n represents an integer of 2 or more,
The weight average molecular weight (Mw) measured by GPC is 10,000 or more. ]

[In formula (II)
X represents a hydrogen atom or an organic group having 1 to 20 carbon atoms.
l represents an integer of 0 to 3. ]

In formula (I), Ar1 represents a tetravalent aromatic group derived from the bifunctional phenolic compound (A). Examples of the bifunctional phenol compound (A) include, for example.
Biphenol compounds such as 4,4'-biphenol, 2,2'-biphenol, etc .;
Dihydroxydiphenyl ether compounds such as 4,4'-dihydroxydiphenyl ether, 2,2'-dihydroxydiphenyl ether, etc.;
Dihydroxydiphenylmethane compounds such as 4,4'-dihydroxydiphenylmethane, 2,2'-dihydroxydiphenylmethane, bis (4-hydroxyphenyl) diphenylmethane, etc. (including derivatives, the same applies hereinafter);
Dihydroxydiphenylethane compounds such as 1,1-bis (4-hydroxyphenyl) ethane (bisphenol E), 1,1-bis (4-hydroxyphenyl) -1-phenylethane, etc.;
2,2-Bis (4-hydroxyphenyl) propane (bisphenol A), 1,1-bis (4-hydroxyphenyl) propane, 1,1-bis (4-hydroxyphenyl) -2-methylpropane, 2,2 -Dihydroxydiphenylpropane compounds such as bis (4-hydroxyphenyl) hexafluoropropane, etc .;
Dihydroxydiphenylbutane compounds such as 1,1-bis (4-hydroxyphenyl) butane, 2,2-bis (4-hydroxyphenyl) butane, etc.;
Dihydroxydiphenylcycloalkane compounds such as 1,1-bis (4-hydroxyphenyl) cyclopentane, 1,1-bis (4-hydroxyphenyl) cyclohexane (bisphenol Z);
Dihydroxydiphenylketone compounds such as 4,4'-dihydroxybenzophenone;
Dihydroxydiphenylfluorene compounds such as 9,9-bis (4-hydroxyphenyl) fluorene;
Dihydroxydiphenylbenzene compounds such as 1,3-bis (4-hydroxyphenoxy) benzene, 1,4-bis (3-hydroxyphenoxy) benzene;
4,4'-[1,3-phenylenebis (1-methyl-ethylidene)] Bisphenol (Mitsui Chemicals'"bisphenolM",4,4'-[1,4-phenylenebis (1-methyl-ethylidene)] Bisphenol (Other bisphenol compounds such as "Bisphenol P" manufactured by Mitsui Chemicals Co., Ltd .;
Such as, a bifunctional phenol compound having a structure in which the OH group and the ortho position thereof can be incorporated into the benzoxazine ring is preferable.
Among these, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxydiphenylmethane, 2,2-bis (4-hydroxyphenyl) propane (bisphenol A) and the like are preferable, and 2,2-bis (4-hydroxyphenyl) is preferable. ) Propane is more preferred.

In formula (I), R1 represents a divalent linear alkylene group having 6 carbon atoms derived from the aliphatic diamine compound (B). As the aliphatic diamine compound (B), a diamine compound having a saturated hydrocarbon group having a main chain skeleton having 6 carbon atoms, for example, 1,6-hexanediamine (hexamethylenediamine) is suitable.

The monofunctional phenol compound (D) is not particularly limited, but is preferably phenol, o-cresol, m-cresol, p-cresol, p-tert-butylphenol, p-octylphenol, p-cumyl. Phenol, dodecylphenol, o-phenylphenol, p-phenylphenol, 1-naphthol, 2-naphthol, m-methoxyphenol, p-methoxyphenol, m-ethoxyphenol, p-ethoxyphenol, 3,4-dimethylphenol, Examples thereof include 3,5-dimethylphenol. Of these, phenol is preferred.

Further, the aldehyde compound (C) can be used for synthesizing the thermosetting resin of the present invention. The aldehyde compound (C) is not particularly limited, but formaldehyde is preferable, and the formaldehyde can be used in the form of paraformaldehyde, which is a polymer thereof, or formalin, which is in the form of an aqueous solution. Is.
In the formula (I), n is the degree of polymerization and represents an integer of 2 or more, but from the viewpoint of improving the mechanical properties before and after curing, n is preferably 20 or more, preferably 25 or more. More preferably, it is more preferably 30 or more, and even more preferably 40 or more. Further, n is preferably 500 or less, more preferably 300 or less, further preferably 200 or less, still more preferably 100 or less, in order to maintain the fluidity at the time of molding.
Examples of the "organic group having 1 to 20 carbon atoms" in X of the formula (II) include methyl, ethyl, tert-butyl, octyl, dodecyl, phenyl, cumyl, methoxy, ethoxy and the like.

The thermosetting resin of the present invention needs to have a weight average molecular weight (Mw) of 10,000 or more as measured by GPC, but from the viewpoint of improving mechanical properties before and after curing, Mw is 15,000 or more. It is preferably 20,000 or more, more preferably 25,000 or more, and even more preferably 30,000 or more. The weight average molecular weight (Mw) is preferably 500,000 or less.

[Manufacturing method of thermosetting resin]
The method for producing a thermosetting resin of the present invention is a method for producing a thermosetting resin having a benzoxazine ring structure in the main chain.
The step (s1) of reacting the bifunctional phenol compound (A), the diamine compound (B), and the aldehyde compound (C), and further the step (s2) of reacting the monofunctional phenol compound (D). Including,
The step (s1) and the step (s2) may be simultaneous, or the step (s1) may be first and the step (s2) may be later.
The diamine compound (B) is a linear aliphatic diamine having 6 carbon atoms.
Step (s1) and step (s2) are both steps in a mixed solvent containing a solvent (L1) and a solvent (L2).
The solvent (L1) is a non-halogen hydrocarbon solvent, and is
The solvent (L2) is characterized by being an aliphatic alcohol-based solvent.

Here, the ratio of the number of moles of the bifunctional phenol compound (A) to the diamine compound (B) is preferably 5.0 / 10.0 to 7.5 / 10.0, and the diamine compound is also preferable. The ratio of the number of moles of (B) to the monofunctional phenol compound (D) is preferably 10.0 / 5.0 to 10.0 / 7.5.

According to such a method for producing a thermosetting resin, it is possible to obtain a thermosetting resin having a benzoxazine structure having an excellent storage stability and a large molecular weight in the main chain.

By reacting the monofunctional phenol compound (D) in the step (s2), the reactive end can be sealed and gelation can be prevented.
In the above production method, the step (s1) of reacting the bifunctional phenol compound (A), the diamine compound (B), and the aldehyde compound (C), and the step (s2) of reacting the monofunctional phenol compound (D). The term may be simultaneous, or the step (s1) may be first and the step (s2) may be later, but it is preferable that the step (s1) and the step (s2) are simultaneously.

Examples of the bifunctional phenol compound (A) include the same compounds already exemplified as (A).

In the above production method, examples of the aliphatic diamine compound (B) include the same compounds already exemplified as (B). With such a suitable configuration, a thermosetting resin having excellent mechanical properties can be obtained.

Examples of the aldehyde compound (C) include the same compounds already exemplified as (C).

Examples of the monofunctional phenol compound (D) include the same compounds already exemplified as (D).

In the above production method, the ratio of the number of moles of the bifunctional phenol compound (A) to the diamine compound (B) is preferably 5.0 / 10.0 to 7.5 / 10.0. Within this range, gelation is unlikely to occur during production, and a high molecular weight product is likely to be obtained.
In the above production method, the ratio of the number of moles of the diamine compound (B) to the monofunctional phenol compound (D) is preferably 10.0 / 5.0 to 10.0 / 7.5. Within this range, gelation is unlikely to occur during production, and a high molecular weight product is likely to be obtained.

In the above-mentioned reaction step (s1), the bifunctional phenol compound (A), the diamine compound (B) and the aldehyde compound (C) are further reacted, and in the above-mentioned reaction step (s2), further monofunctional. The phenol compound (D) is reacted while heating in a mixed solvent containing the solvent (L1) and the solvent (L2).

The non-halogen hydrocarbon solvent of the solvent (L1) is a hydrocarbon solvent that does not contain a halogen atom and does not contain a hetero atom such as an oxygen atom, a nitrogen atom, or a sulfur atom, and is an aliphatic hydrocarbon or an alicyclic type. It may be a hydrocarbon, an aromatic hydrocarbon, or the like. Among these, toluene and / or xylene are preferable, and toluene is more preferable. The aliphatic alcohol solvent of the solvent (L2) is a compound in which one or more hydroxyl groups are bonded to an aliphatic hydrocarbon. Among these, at least one selected from the group consisting of methanol, ethanol, propanol and butanol (including structural isomers) is preferable, and at least one selected from the group consisting of methanol, ethanol and propanol. Is more preferable.
The volume ratio of the solvent (L1) to the solvent (L2) is preferably (L1) / (L2) = 50/50 to 80/20.
The solvent (L1) is necessary because the raw materials, the phenol compound (A), the diamine compound (B), and the monofunctional phenol compound (D) have good solubility. With a halogen-based solvent such as chloroform alone or an ether-based solvent such as THF alone, it is difficult to obtain a product with a high degree of polymerization, and there is a problem that chloroform is an environmental problem derived from halogen and THF is easy to form a gel. Not always preferable. Further, the solvent (L2) has a role of suppressing gelation, and a mixed solvent of the solvent (L1) and the solvent (L2) is necessary for the solubility of the polymer as a product. That is, although the raw materials (A), (B), and (D) are dissolved only by the solvent (L1), there is a problem that the product is easily gelled, and the solubility of the raw material compound is high only by the solvent (L2). There is a problem that it is low.

The reaction temperature and reaction time are not particularly limited, but usually, the reaction may be carried out at a temperature of about 120 ° C. from room temperature for several tens of minutes to several hours. In the present invention, it is particularly preferable to react at 30 to 110 ° C. for 20 minutes to 9 hours because the reaction proceeds to the polymer capable of exhibiting the function as the thermosetting resin according to the present invention.

In addition, removing the water generated during the reaction to the outside of the system is also an effective method for advancing the reaction. A polymer can be precipitated by adding, for example, a large amount of a poor solvent such as methanol to the solution after the reaction, and the desired polymer can be obtained by separating and drying the polymer.

[Thermosetting composition]
It is also possible to prepare and use a thermosetting composition containing the thermosetting resin of the present invention as a main component and another thermosetting resin, a thermoplastic resin, and a compounding agent as subcomponents.

Examples of other thermosetting resins include epoxy resins, thermosetting modified polyphenylene ether resins, thermosetting polyimide resins, silicon resins, melamine resins, urea resins, allyl resins, phenol resins, unsaturated polyester resins, and bis. Examples thereof include maleimide-based resin, alkyd resin, furan resin, polyurethane resin, and aniline resin.

Examples of the thermoplastic resin include a thermoplastic epoxy resin and a thermoplastic polyimide resin.

As a compounding agent, if necessary, a flame retardant, a nucleating agent, an antioxidant, an antioxidant, a heat stabilizer, a light stabilizer, an ultraviolet absorber, a lubricant, a flame retardant, an antistatic agent, and an antifogging agent. Examples include agents, fillers, softeners, plasticizers, colorants and the like. These may be used alone or in combination of two or more. It is also possible to use a reactive or non-reactive solvent.

[Thermosetting resin molded body (uncured molded body)]
Since the thermosetting resin of the present invention or its composition has moldability even before curing, it is possible to use an uncured molded product molded without curing according to its use and purpose. You can. This molding temperature (the maximum temperature among them when the temperature is gradually raised) is not particularly limited, but is preferably room temperature or higher and lower than 200 ° C, and more preferably 60 ° C or higher and 180 ° C or lower. , 100 ° C. or higher and 160 ° C. or lower are most preferable. If the molding temperature is 200 ° C. or higher, curing may proceed and a desired uncured molded product may not be obtained.
The size and shape of the uncured molded product are not particularly limited, and examples thereof include a film shape, a sheet shape / plate shape, a block shape, and the like, and other parts (for example, an adhesive layer) may be provided.
This uncured molded product can be used as a precursor of the cured product molded product described later, and can also be used, for example, as an adhesive sheet having curability.
As for the characteristics of the uncured molded product, it is preferable that the measured value by the method of the example described later is 5% or more.

[Molded product of cured product (cured molded product)]
A cured molded product can be obtained by applying heat to a molded product (uncured molded product) of the above-mentioned thermosetting resin to cure it. Further, a cured molded product can also be obtained by molding the thermosetting resin of the present invention or a composition thereof without passing through an uncured molded product and simultaneously applying heat to cure the resin. The curing temperature (the maximum temperature among them when the temperature is gradually increased) is not particularly limited, but is preferably 200 ° C. or higher and 300 ° C. or lower, and more preferably 220 ° C. or higher and 280 ° C. or lower. Most preferably, it is 240 ° C. or higher and 260 ° C. or lower. If the curing temperature is less than 200 ° C., the molded product may be insufficiently cured. Further, if the curing temperature is 300 ° C. or higher, thermal decomposition may proceed and a desired cured molded product may not be obtained.
The size and shape of the cured molded product are not particularly limited, and examples thereof include a film shape, a sheet shape / plate shape, a block shape, and the like, and other parts (for example, an adhesive layer) may be provided.
The cured molded body can be suitably used for electronic parts / devices and their materials, particularly multilayer substrates, laminated boards, encapsulants, adhesives, etc. that require excellent dielectric properties, and other aircraft members, etc. It can also be used for applications such as automobile parts and building parts.

Examples and comparative examples for explaining the present invention are shown below, but the present invention is not limited thereto. First, the measurement conditions for each physical property were as follows.
〔Test method〕
(1) Glass transition temperature (Tg)
For uncured and cured products in film shape, measure the DSC curve under the condition of a differential scanning calorimeter DSC7000X (DSC, manufactured by Hitachi High-Tech Science) under a nitrogen stream (40 mL / min) and a temperature rise rate of 10 ° C / min. did. The temperature of the inflection point of the DSC curve was defined as the glass transition temperature.
(2) Tensile elastic modulus, tensile breaking strength, tensile breaking elongation A cured product in the form of a film was subjected to a tensile test 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 shape of the test piece was 50 mm in length and 3 mm in width.

[Example 1]
Bisphenol A (manufactured by Tokyo Chemical Industry (TCI)) 3.1956 g (0.014 mol), hexamethylenediamine (manufactured by Tokyo Chemical Industry (TCI)) in a mixed solvent of toluene (30 mL) and ethanol (15 mL) 2. 3260 g (0.020 mol), paraformaldehyde (Merch) 2.5826 g (0.086 mol), phenol (Tokyo Chemical Industry (TCI)) 1.1280 g (0.012 mol) were added and reacted at 60 ° C. I let you. The reaction was stopped after 5 hours. After cooling the reaction solution to room temperature, the solution was separated three times with 100 mL of 0.1N sodium hydrogen carbonate solution. The reaction solution after washing with sodium sulfate was dehydrated and filtered. The solvent was removed by heating with an evaporator under reduced pressure, and the mixture was dried under reduced pressure at 50 ° C. in a vacuum oven to obtain the desired compound. In the measurement of the molecular weight by GPC, the number average molecular weight (Mn) was 3970 and the weight average molecular weight (Mw) was 38829 in terms of standard polystyrene.
This benzoxazine powder was heated at 120 ° C. for 40 minutes using a hot press and heated to 160 ° C. to obtain a film-like uncured product. Further, the film was cured by heating in an oven at 200 ° C. for 1 hour, 240 ° C. for 1 hour, and 260 ° C. for 30 minutes to obtain a cured product in the form of a film. Table 1 shows the characteristics of the uncured and cured products of the film shape.

[Comparative Example 1]
Bisphenol A (manufactured by Tokyo Chemical Industry (TCI)) 4.1505 g (0.018 mol), hexamethylenediamine (Tokyo Chemical Industry (TCI)) in a mixed solvent of toluene (38.6 mL) and isobutanol (6.8 mL). ) 2.3243g (0.020mol), Paraformaldehyde (Merch) 3.6053g (0.120mol), Phenol (Tokyo Chemical Industry (TCI)) 0.5149g (0.005mol) , 90 ° C. The reaction was stopped after 5 hours. The reaction solution was poured into 800 mL of methanol to precipitate the target compound. The target compound was separated by the subsequent separation and dried under reduced pressure at 45 ° C. in a vacuum oven to obtain the target compound. In the measurement of the molecular weight by GPC, the number average molecular weight (Mn) was 2733 and the weight average molecular weight (Mw) was 7146 in terms of standard polystyrene.
This benzoxazine powder was heated at 120 ° C. for 40 minutes using a hot press and heated to 160 ° C. to obtain a film-like uncured product. Further, the film was cured by heating in an oven at 200 ° C. for 1 hour, 240 ° C. for 1 hour, and 260 ° C. for 30 minutes to obtain a cured product in the form of a film. Table 1 shows the characteristics of the uncured and cured products of the film shape.

[Comparative Example 2]
In chloroform (50 mL), bisphenol A (manufactured by Tokyo Chemical Industry (TCI)) 4.6045 g (0.020 mol), hexamethylenediamine (manufactured by Tokyo Chemical Industry (TCI)) 2.3430 g (0.020 mol), para. 2.6072 g (0.087 mol) of formaldehyde (manufactured by Merch) was added and reacted at 60 ° C. The reaction was stopped after 5 hours. After cooling the reaction solution to room temperature, the solution was separated three times with 100 mL of 1N sodium hydrogen carbonate solution. The reaction solution after washing with sodium sulfate was dehydrated and filtered. The solvent was removed by heating with an evaporator under reduced pressure, and the mixture was dried under reduced pressure at 50 ° C. in a vacuum oven to obtain the desired compound. In the measurement of the molecular weight by GPC, the number average molecular weight (Mn) was 4502 and the weight average molecular weight (Mw) was 22329 in terms of standard polystyrene.
This benzoxazine powder was heated at 120 ° C. for 40 minutes using a hot press and heated to 160 ° C. to obtain a film-like uncured product. Further, the film was cured by heating in an oven at 200 ° C. for 1 hour, 240 ° C. for 1 hour, and 260 ° C. for 30 minutes to obtain a cured product in the form of a film. Table 1 shows the characteristics of the uncured and cured products of the film shape.

[Comparative Example 3]
In chloroform (150 mL), bisphenol A (manufactured by Tokyo Chemical Industry (TCI)) 9.5889 g (0.042 mol), hexamethylenediamine (manufactured by Tokyo Chemical Industry (TCI)) 6.9718 g (0.060 mol), 7.7485 g (0.258 mol) of paraformaldehyde (manufactured by Merch) and 3.3887 g (0.036 mol) of phenol (manufactured by Tokyo Chemical Industry (TCI)) were added and reacted at 60 ° C. The reaction was stopped after 5 hours. After cooling the reaction solution to room temperature, the solution was separated three times with 300 mL of 0.1N sodium hydrogen carbonate solution. The reaction solution after washing with sodium sulfate was dehydrated and filtered. The solvent was removed by heating with an evaporator under reduced pressure, and the mixture was dried under reduced pressure at 40 ° C. in a vacuum oven to obtain the desired compound. In the measurement of the molecular weight by GPC, the number average molecular weight (Mn) was 1884 and the weight average molecular weight (Mw) was 3847 in terms of standard polystyrene.
This benzoxazine powder was heated at 120 ° C. for 40 minutes using a hot press and heated to 160 ° C. to obtain a film-like uncured product. Further, the film was cured by heating in an oven at 200 ° C. for 1 hour, 240 ° C. for 1 hour, and 260 ° C. for 30 minutes to obtain a cured product in the form of a film. Table 1 shows the characteristics of the uncured and cured products of the film shape.

[Comparative Example 4]
In THF (50 mL), bisphenol A (manufactured by Tokyo Chemical Industry (TCI)) 3.1961 g (0.014 mol), hexamethylenediamine (manufactured by Tokyo Chemical Industry (TCI)) 2.3242 g (0.020 mol), 2.5826 g (0.086 mol) of paraformaldehyde (manufactured by Merch) and 1.1293 g (0.012 mol) of phenol (manufactured by Tokyo Chemical Industry (TCI)) were added and reacted at 65 ° C. The reaction was stopped after 6 hours. An insoluble gel was formed in the solution. After cooling the reaction solution to room temperature, the gel was filtered, and the filtrate was poured into 200 mL of hexane to precipitate the target compound. The target compound was separated by the subsequent separation and dried under reduced pressure at 50 ° C. in a vacuum oven to obtain a solid powder. However, this solid powder was an insoluble gel. In the measurement of the molecular weight of the soluble part by GPC, the number average molecular weight (Mn) was 2631 and the weight average molecular weight (Mw) was 9064 in terms of standard polystyrene.

Comparative Example 2 is a benzoxazine that is not end-capped with phenol. Although benzoxazine having a high molecular weight (Mw) is obtained, it is considered that the stability (storage stability) in a solution state dissolved in a solvent is inferior due to the absence of the terminal cap.

In Comparative Example 3, a part of the bisphenol A of Comparative Example 2 was replaced with a double molar amount of phenol to cause terminal encapsulation. In Comparative Example 3 and Comparative Example 2, the ratio of the amount of functional groups of amine to the total amount of phenolic functional groups is the same. However, in Comparative Example 3, since only benzoxazine having a low molecular weight (Mw) was obtained due to the side effect of end sealing, the tensile elastic modulus (GPa), tensile breaking strength (MPa), and tensile breaking elongation were compared with Comparative Example 2. All of (%) are inferior.

In Comparative Example 4, the solvent of Comparative Example 3 was changed to THF. However, gel was formed after the reaction was completed, and the reaction stability was inferior, and the molecular weight of the obtained benzoxazine was also low.

In Example 1, the solvents of Comparative Example 3 and Comparative Example 4 are changed to the mixed solvent of the present invention. It can be seen that benzoxazine having a high molecular weight (Mw) is obtained by the effect of the present invention. In addition, it can be seen that the glass transition point is low and the tensile elongation at break of the pre-cured film is also excellent. From this, it is considered that the film is easy to handle before curing.

Since the benzoxazine of Comparative Example 1 has a low molecular weight (Mw), it is inferior in all of the tensile elastic modulus (GPa), the tensile breaking strength (MPa), and the tensile breaking elongation (%) as compared with Example 1. It is considered that the handleability of the film before curing is inferior.

Claims (7)

A thermosetting resin having a benzoxazine ring structure in a main chain represented by the general formula (I).

[In formula (I)
Ar1 represents a tetravalent aromatic group derived from the bifunctional phenol compound (A).
R1 represents a divalent linear alkylene group having 6 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 (D), and A and B may be the same or different.
n represents an integer of 2 or more,
The weight average molecular weight (Mw) measured by GPC is 10,000 or more. ]

[In formula (II)
X represents a hydrogen atom or an organic group having 1 to 20 carbon atoms.
l represents an integer of 0 to 3. ] A composition comprising the thermosetting resin according to claim 1. An uncured molded product obtained by molding the thermosetting resin of claim 1 or the composition of claim 2. A cured molded product obtained by curing the thermosetting resin according to claim 1, the composition according to claim 2, or the uncured molded product according to claim 3. A method for producing a thermosetting resin having a benzoxazine ring structure in the main chain.
The step (s1) of reacting the bifunctional phenol compound (A), the diamine compound (B), and the aldehyde compound (C),
Further, the step (s2) of reacting the monofunctional phenol compound (D) is included.
The step (s1) and the step (s2) may be simultaneous, or the step (s1) may be first and the step (s2) may be later.
The diamine compound (B) is a linear aliphatic diamine having 6 carbon atoms.
Step (s1) and step (s2) are steps in a mixed solvent containing a solvent (L1) and a solvent (L2).
The solvent (L1) is a non-halogen hydrocarbon solvent, and is
The solvent (L2) is an aliphatic alcohol-based solvent.
A method for manufacturing a thermosetting resin. The solvent (L1) is toluene and / or xylene,
The solvent (L2) is at least one selected from the group consisting of methanol, ethanol, propanol and butanol (including structural isomers).
The method for producing a thermosetting resin according to claim 5. The volume ratio of the solvent (L1) to the solvent (L2) is (L1) / (L2) = 50/50 to 80/20.
The method for producing a thermosetting resin according to claim 5 or 6.