WO2023032943A1 - Heat-curable composition - Google Patents

Abstract

A heat-curable composition including a main agent with a glycidyl ether group, and a solid latent curing agent, wherein the particle size prior to heat curing is 40 μm or less.

Description

thermosetting composition

The present disclosure relates to thermosetting compositions.

Thermosetting compositions are widely used in various applications such as fiber-reinforced plastics and adhesive materials. Such thermosetting compositions are disclosed, for example, in US Pat.

JP 2014-132064 A JP 2011-69653 A

Technologies related to thermosetting compositions have been conventionally studied, including Patent Document 1 and Patent Document 2. However, the current situation is that the technique for improving the mechanical properties of the resulting thermoset is insufficient.

The present disclosure has been made in view of such circumstances, and the problem to be solved by one embodiment of the present disclosure is a thermosetting composition capable of forming a thermoset having excellent mechanical properties. It is to provide things.

The present disclosure includes the following aspects.
<1> A thermosetting composition containing a main agent having a glycidyl ether group and a solid latent curing agent, and having a particle size of 40 µm or less before thermosetting.
<2> The thermosetting composition according to <1>, which has a viscosity at 25°C of 24 Pa·s or less as measured with an E-type viscometer.
<3> A thermoset obtained by heat-curing the thermosetting composition at 150 ° C. for 30 minutes is added with 15.8 times the mass of acetone of the thermoset, and ultrasonically treated for 30 minutes with an ultrasonic disperser. The thermosetting composition according to <1> or <2>, wherein the dry matter of the acetone extraction solution obtained by applying is 1.1% by mass or less with respect to the total amount of the thermosetting composition.
<4> The thermosetting composition according to any one of <1> to <3>, wherein the latent curing agent is 1 equivalent with respect to the epoxy equivalent of the main agent.
<5> The thermosetting composition according to any one of <1> to <4>, wherein the latent curing agent contains dicyandiamide.
<6> A thermoset obtained by heat-curing the thermosetting composition at 150 ° C. for 30 minutes is added with acetone having a mass 15.8 times the weight of the thermoset, and ultrasonically treated for 30 minutes with an ultrasonic disperser. 2200 cm ^-1 obtained by drawing a baseline at 2260 cm ^-1 to 2120 cm ^-1 for the spectroscopic spectrum obtained by analyzing the acetone extraction solution obtained by applying the ATR method by FT-IR using diamond crystals. The intensity ratio I CN /ICO between the intensity I _CN derived _from the CN triple bond _and the intensity I _CO derived from the CO single bond at 1250 cm ^-1 obtained by drawing the baseline at 1280 cm ^-1 to 1200 cm ^-1 is The thermosetting composition according to <5>, which is 0.036 or less.
<7> The thermosetting composition according to <6>, wherein the intensity ratio I _CN /I _CO obtained from the acetone extraction solution has a coefficient of variation obtained by dividing the standard deviation by the average value of 0.22 or less. thing.
<8> The thermosetting composition according to any one of <1> to <7>, wherein the main agent is bisphenol A diglycidyl ether.
<9> The thermosetting composition according to any one of <1> to <8>, which contains a curing accelerator.
<10> The thermosetting composition according to <9>, wherein the curing accelerator contains 3-(3,4-dichlorophenyl)-1,1-dimethylurea.
<11> The thermosetting composition according to any one of <1> to <10>, comprising a core-shell type rubber.
<12> The thermosetting composition according to <11>, wherein the core-shell type rubber comprises acryl-butadiene core-shell rubber.

According to one embodiment of the present disclosure, a thermosetting composition capable of forming a thermoset with excellent mechanical properties is provided.

Details of the thermosetting composition according to the present disclosure are described below.
In the present disclosure, a numerical range indicated using the symbol "~" means a range including the numerical values before and after the symbol "~" as the minimum and maximum values, respectively.

In the numerical ranges described step by step in the present disclosure, the upper limit or lower limit described in a certain numerical range may be replaced with the upper limit or lower limit of another numerical range described step by step. In addition, in the numerical ranges described in the present disclosure, upper or lower limits described in a certain numerical range may be replaced with values shown in Examples.

In the present disclosure, a combination of two or more preferred aspects is a more preferred aspect.
In the present disclosure, the content of each component means the total amount of the multiple types of substances unless otherwise specified when there are multiple types of substances corresponding to each component.

<Thermosetting composition>
The thermosetting composition according to the present disclosure contains a main agent having a glycidyl ether group and a solid latent curing agent, and has a particle size of 40 μm or less before heat curing.

Thermosetting compositions containing a main agent and a latent curing agent are widely used, and thermosetting products obtained from such thermosetting compositions are evaluated for degree of curing and mechanical properties. It is For example, as described in Patent Literature 1 and Patent Literature 2, spectroscopy is used to evaluate the degree of curing. However, the techniques described in these patent documents may result in insufficient mechanical properties of thermosets.

On the other hand, the thermosetting composition according to the present disclosure contains a latent curing agent and has a particle size of 40 μm or less. That is, the particle size before heat curing is 40 μm or less, and the latent curing agent is uniformly dispersed. Therefore, when the thermosetting composition is cured, the thermosetting progresses uniformly, so local unevenness in curing can be reduced. Therefore, the degree of thermosetting can be increased as a whole, and a thermoset having excellent mechanical properties can be obtained.

[Main agent having a glycidyl ether group]
The main agent having a glycidyl ether group (hereinafter sometimes simply referred to as "main agent") is not particularly limited as long as it has a glycidyl ether group. For example, bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, triphenylglycidyl ether methane, tris(glycidyloxy)methane, trimethylolpropane triglycidyl ether, trimethylolethane triglycidyl ether, tetraphenylglycidyl ether ethane, pentaerythritol poly Examples include glycidyl ether, tetraglycidyl ether of 1,6-bis(2-naphthyl)methane, triglycidyl ether of phloroglucinol, and epoxy resins. Examples of epoxy resins include phenol novolak type epoxy resin, alkylphenol novolak type epoxy resin, naphthalene-containing novolak type epoxy resin, bisphenol A novolak type epoxy resin, triphenylmethane type (trisphenolmethane type) epoxy resin, and tetrakisphenolethane type epoxy resin. resins, dicyclopentadiene type epoxy resins, phenol-biphenyl type epoxy resins, novolac type epoxy resins such as mixtures of crystalline epoxy resins and novolac type epoxy resins, bisphenol type epoxy resins, biphenyl type epoxy resins, stilbene type epoxy resins, naphthalene type epoxy resin, alicyclic epoxy resin, bromine-containing epoxy resin, cyclohexane type epoxy resin, adamantane type epoxy resin, triglycidyl isocyanurate and the like.

Main agents having glycidyl ether groups are bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, triphenylglycidyl ether methane, tris(glycidyloxy)methane, trimethylolpropane triglycidyl ether, trimethylolethane triglycidyl ether, and tetraphenylglycidyl. It preferably contains one or more selected from the group consisting of ether ethane, pentaerythritol polyglycidyl ether, tetraglycidyl ether of 1,6-bis(2-naphthyl)methane, and triglycidyl ether of phloroglucinol.

From the viewpoint of thermosetting, the main agent preferably contains bisphenol A diglycidyl ether.
A main agent may be used individually by 1 type, and may be used in combination of 2 or more types.

The content of the main agent is not particularly limited, and may be, for example, 40% by mass or more relative to the total amount of the thermosetting composition.
[Latent curing agent]
The type of latent curing agent is not particularly limited, and examples thereof include dicyandiamide, imidazole compounds, organic acid hydrazides, and amine imide compounds. A latent curing agent is a compound that latently has the function of initiating curing by heat.

From the viewpoint of thermosetting, the latent curing agent preferably contains dicyandiamide.
A latent hardening agent may be used individually by 1 type, and may be used in combination of 2 or more types.
The content of the latent curing agent may be adjusted as appropriate in consideration of the epoxy equivalent of the main agent and the equivalent of the latent curing agent. It is preferably between 0.36 equivalents and 0.72 equivalents.

[Granularity]
The thermosetting composition has a particle size of 40 μm or less before heat curing. As a result, the latent curing agent is uniformly dispersed, and when the thermosetting composition is cured, the thermosetting progresses uniformly, so that local unevenness in curing can be reduced. Therefore, the degree of thermosetting can be increased as a whole, and a thermoset having excellent mechanical properties can be obtained.

The particle size is measured by the grind gauge method according to JIS K 5600-2-5:1999.
[viscosity]
The thermosetting composition preferably has a viscosity at 25° C. measured with an E-type viscometer (hereinafter sometimes simply referred to as “viscosity”) of 25 Pa·s or less. As a result, the latent curing agent is more uniformly dispersed, making it easier to obtain a thermoset product with excellent mechanical properties.

The viscosity is more preferably 23 Pa·s or less, even more preferably 22 Pa·s or less.
Moreover, the lower limit of the viscosity is not particularly limited, and the lower the better.

[Acetone extraction rate]
A thermoset obtained by thermally curing the thermosetting composition at 150 ° C. for 30 minutes is added with 15.8 times the mass of acetone and subjected to ultrasonic treatment for 30 minutes with an ultrasonic disperser. It is preferable that the dry matter of the resulting acetone-extracted solution (hereinafter sometimes simply referred to as "acetone-extracted liquid") is 1.2% by mass or less with respect to the total amount of the thermoset. The mass ratio of the dried product to the total amount of the thermoset product is sometimes called "acetone extraction rate" [%].

The acetone extraction rate corresponds to the ratio of the uncured thermosetting composition extracted from the thermosetting material, and is an indicator of the degree of thermosetting. That is, it can be said that the lower the acetone extraction rate, the smaller the proportion of uncured thermosetting composition and the higher the degree of thermosetting. By using the acetone extraction rate, it is possible to detect a trace amount of uncured thermosetting composition of 1.1% by mass or less, and to evaluate the degree of thermosetting with high sensitivity.

By setting the acetone extraction rate to 1.2% by mass or less, the degree of thermosetting can be further increased, and it becomes easier to obtain a thermoset having excellent mechanical properties.
The acetone extraction rate is more preferably 1.1% by mass or less, and even more preferably 1.0% by mass or less.

Moreover, the lower limit of the acetone extraction rate is not particularly limited, and the lower the better.
[Spectral intensity ratio]
When dicyandiamide is used as the latent curing agent, the heat curing of the thermosetting composition is performed as follows by the spectrum intensity ratio determined by the ATR (Attenuated Total Reflection) method by FT-IR (Fourier Transform Infrared Spectroscopy). degree can be evaluated.

That is, the 2200 cm ^-1 CN triple bond obtained by drawing the baseline at 2260 cm ^-1 to 2120 cm ^-1 for the spectroscopic spectrum obtained by analyzing the acetone extract by the ATR method by FT-IR using diamond crystals The intensity ratio I _CN /ICO between the intensity I CN derived _from and the intensity I _CO derived from the CO single bond at 1250 cm ⁻¹ obtained by drawing the baseline at 1280 cm ⁻¹ to 1200 ^cm ₋₁ is 0.036. The following are preferable.

The intensity _ICO is the intensity of the peak derived from the CO single bond of the main agent, and is the reference intensity at which the amount of substance does not change before and after heat curing. On the other hand, the intensity I _CN is a peak derived from the CN triple bond of dicyandiamide, and decreases as the CN triple bond is consumed as the heat curing progresses. The intensity ratio I _CN /I _CO corresponds to the residual proportion of unreacted CN triple bonds and is an index of the degree of thermosetting. That is, it can be said that the lower the strength ratio I _CN / _ICO is, the smaller the ratio of remaining unreacted CN triple bonds is, and the higher the degree of thermosetting.

By setting the strength ratio I _CN /I _CO to 0.036 or less, the degree of thermosetting can be further increased, and it becomes easier to obtain a thermoset having excellent mechanical properties.
The intensity ratio I _CN /I _CO is more preferably 0.033 or less, even more preferably 0.030 or less.

Also, the lower limit of the intensity ratio I _CN /I _CO is not particularly limited, and the lower the better.
[Coefficient of variation]
Regarding the intensity ratio I _CN /I _CO obtained from the acetone extraction solution, the coefficient of variation obtained by dividing the standard deviation by the average value is preferably 0.225 or less.

The standard deviation and average value are obtained by collecting samples from five randomly selected locations of the thermosetting material obtained by thermally curing the thermosetting composition at 150 ° C. for 30 minutes, and the acetone extraction solution obtained from each sample. It is calculated from the intensity ratio I _CN / _ICO .

It can be said that the smaller the coefficient of variation, the smaller the unevenness of local hardening. Therefore, the degree of thermosetting can be increased as a whole, and it becomes easier to obtain a thermoset having excellent mechanical properties.
The coefficient of variation is more preferably 0.22 or less, even more preferably 0.215 or less.

Moreover, the lower limit of the coefficient of variation is not particularly limited, and the lower the better.
[Other ingredients]
In addition to the above components, the thermosetting composition contains a curing accelerator, core-shell type rubber, glass fiber, carbon fiber, carbon nanotube, carbon nanofiber, antifoaming agent, plasticizer, pigment, leveling agent, surfactant, oxidizing Inhibitors, UV absorbers, and the like may be included. Each of these components may be used singly or in combination of two or more.

Examples of curing accelerators include 3-(3,4-dichlorophenyl)-1,1-dimethylurea, phosphine compounds, imidazole compounds, quaternary ammonium salts, and tertiary amines. From the viewpoint of thermosetting, the curing accelerator preferably contains 3-(3,4-dichlorophenyl)-1,1-dimethylurea.

The content of the curing accelerator is not particularly limited, and may be appropriately set in consideration of the application.
Examples of core-shell type rubber include acryl-butadiene core-shell rubber. By including the core-shell type rubber in the thermosetting composition, ductility can be imparted to the resulting thermoset. In addition, since the thermosetting composition has a particle size of 40 μm or less before being heat-cured, the inclusion of the acryl-butadiene core-shell rubber can more preferably exhibit ductility.

<Method for producing thermosetting composition>
Although the method for producing the thermosetting composition according to the present disclosure is not particularly limited, the following method for producing the thermosetting composition according to the present disclosure can be suitably used.

A method for producing a thermosetting composition according to the present disclosure includes a step of dispersing a mixture containing a main agent having a glycidyl ether group and a solid latent curing agent with three rolls.
By dispersing the mixture using three rolls, it becomes easy to make the particle size 40 μm or less before heat curing. Thereby, a thermosetting composition according to the present disclosure can be produced.

The mixture may contain the above other components in addition to the main agent and the latent curing agent. The details of the main agent, latent curing agent and other components are as described above.

EXAMPLES Hereinafter, the present disclosure will be described more specifically with reference to Examples. However, the present disclosure is not limited to these examples.
<Preparation of thermosetting composition>
[Example 1]
A mixture was prepared by mixing the following main agent, latent curing agent, curing accelerator and additive (core-shell type rubber).
- Main agent having a glycidyl ether group: bisphenol A diglycidyl ether ("jER 828" manufactured by Mitsubishi Chemical Corporation, epoxy equivalent: 190 g/eq): 85 parts by mass - A mixture of a main agent having a glycidyl ether group and a core-shell type rubber: bisphenol A Mixture of glycidyl ether and polybutadiene-based core-shell type rubber ("Kane Ace MX-150" manufactured by Kaneka Corporation, a mixture of 60% by mass of bisphenol A diglycidyl ether and 40% by mass of polybutadiene-based core-shell type rubber, epoxy equivalent: 190 g /eq): 25 parts by mass Solid latent curing agent dicyandiamide ("jER Cure DICY7" manufactured by Mitsubishi Chemical Corporation, 21.02 g/eq) (0.54 equivalents relative to 1 equivalent of epoxy as the main agent): 6 masses Part Curing accelerator: 3-(3,4-dichlorophenyl)-1,1-dimethylurea (“DCMU-99” manufactured by Hodogaya Chemical Industry Co., Ltd.) 3 parts by mass After dispersing the above mixture with three rolls, the planet Using a Lee mixer, the mixture was stirred at 20°C for 10 minutes. Thus, a thermosetting composition of Example 1 was produced.

[Comparative Example 1]
A mixture prepared in the same manner as in Example 1 was stirred at 30° C. for 5 minutes using a planetary mixer. Thus, a thermosetting composition of Comparative Example 1 was produced.

[Comparative Example 2]
A mixture prepared in the same manner as in Example 1 was stirred at 10° C. for 90 minutes using a planetary mixer. Thus, a thermosetting composition of Comparative Example 2 was produced.

<Preparation of thermoset>
The thermosetting composition is poured into a molding jig (two aluminum plates coated with Teflon (registered trademark) are stacked via a 4 mm thick spacer) and heat cured in a constant temperature bath at 150°C for 30 minutes. Thus, a plate-shaped thermoset material having a thickness of 4 mm was obtained.

<Evaluation of thermosetting composition and thermoset>
Particle size, viscosity, acetone extraction rate, strength ratio I _CN /I _CO , coefficient of variation, tensile strength, elongation at break, and flexural modulus were evaluated for the thermosetting composition and thermoset according to the following procedures.

[Granularity]
The particle size was measured by the grain gauge (grind gauge) method according to JIS K 5600-2-5:1999.

[viscosity]
Using an E-type viscometer (“TV-25 type” manufactured by Toki Sangyo Co., Ltd.), the viscosity of the thermosetting composition at 25° C. was measured.

[Acetone extraction rate]
Samples were taken from five randomly selected locations on the thermoset.
An acetone extraction solution was obtained by adding 15.8 times the mass of acetone to the collected sample and subjecting it to ultrasonic treatment for 30 minutes with an ultrasonic disperser. The acetone extract was dried at 25° C. for 2 days, and the mass of the dried product obtained was measured. The acetone extraction rate was calculated by dividing the mass of the dry matter by the mass of the sample.

The acetone extraction rate was calculated for five samples, and the average value thereof was taken as the acetone extraction rate of the thermoset.
[Spectral intensity ratio]
Acetone extracts were obtained for the five samples in a manner similar to that described above for acetone extractability.

The acetone extract was analyzed by the ATR method by FT-IR using a diamond crystal to obtain a spectroscopic spectrum. For the resulting spectroscopic spectrum, the intensity I _CN derived from the CN triple bond at 2200 cm ^-1 obtained by drawing a baseline at 2260 cm ^-1 to 2120 cm ^-1 and the baseline at 1280 cm ^-1 to 1200 cm ^-1 The intensity ratio I _CN /I _CO with the intensity I _CO derived from the resulting 1250 cm ⁻¹ CO single bond was calculated.

The intensity ratio I _CN / _ICO was calculated for the five acetone extracts, and the average value thereof was taken as the intensity ratio I _CN / _ICO of the thermoset.
[Coefficient of variation]
Using the intensity ratio I _CN /I _CO obtained from the five acetone extracts described above, the standard deviation was calculated and the coefficient of variation was calculated by dividing the standard deviation by the mean.

[Tensile strength]
The tensile strength and elongation at break of the thermoset were measured by performing a tensile test according to JIS K 7238-2:2009.

[Flexural modulus]
The flexural modulus of the thermoset was measured by performing a flexural test according to JIS K 7238-2:2009. Also, in the bending test, the presence or absence of cracks in the thermoset was confirmed.

Table 1 shows the above evaluation results.

　実施例１の熱硬化性組成物を用いることにより、比較例１及び比較例２と同等の引張強度及び曲げ弾性率を達成しつつ、破断伸びがより優れ、かつ、割れが抑制された熱硬化物、すなわち、機械特性に優れた熱硬化物を得ることができた。

By using the thermosetting composition of Example 1, while achieving tensile strength and flexural modulus equivalent to those of Comparative Examples 1 and 2, the elongation at break is superior, and cracking is suppressed. It was possible to obtain a product, that is, a thermoset product with excellent mechanical properties.

On the other hand, in Comparative Examples 1 and 2, since the particle size of the thermosetting composition was large, the elongation at break of the thermoset was small, and the thermoset was cracked in the bending test, resulting in poor mechanical properties.

Claims (12)

A thermosetting composition containing a main agent having a glycidyl ether group and a solid latent curing agent, and having a particle size of 40 μm or less before thermosetting. The thermosetting composition according to claim 1, wherein the viscosity at 25°C measured with an E-type viscometer is 25 Pa·s or less. A thermoset obtained by thermally curing the thermosetting composition at 150 ° C. for 30 minutes is added with 15.8 times the mass of acetone of the thermoset and subjected to ultrasonic treatment for 30 minutes with an ultrasonic disperser. 3. The thermosetting composition according to claim 1, wherein the dried product of the acetone extraction solution obtained by application is 1.2% by mass or less based on the total amount of the thermosetting composition. The thermosetting composition according to any one of claims 1 to 3, wherein the latent curing agent is 0.36 to 0.72 equivalents with respect to 1 equivalent of epoxy of the main agent. The thermosetting composition according to any one of claims 1 to 4, wherein the latent curing agent contains dicyandiamide. A thermoset obtained by thermally curing the thermosetting composition at 150 ° C. for 30 minutes is added with 15.8 times the mass of acetone of the thermoset and subjected to ultrasonic treatment for 30 minutes with an ultrasonic disperser. CN of 2200 cm ^-1 obtained by drawing a baseline at 2260 cm ^-1 to 2120 cm ^-1 for the spectroscopic spectrum obtained by analyzing the acetone extraction solution obtained by applying it by the ATR method by FT-IR using a diamond crystal The intensity ratio I _{CN /} ICO between ^the intensity I CN derived from the triple _bond and the intensity I _CO derived from the CO single bond at 1250 cm ^-1 obtained by drawing the baseline at 1280 cm ^-1 to 1200 cm _-1 is 0 6. The thermosetting composition of claim 5, which is less than or equal to 0.036. 7. The thermosetting composition according to claim 6, wherein the intensity ratio _ICN / _ICO obtained from the acetone-extracted solution has a coefficient of variation obtained by dividing the standard deviation by the average value of 0.225 or less. The thermosetting composition according to any one of claims 1 to 7, wherein the main ingredient is bisphenol A diglycidyl ether. The thermosetting composition according to any one of claims 1 to 8, which contains a curing accelerator. The thermosetting composition according to claim 9, wherein the curing accelerator comprises 3-(3,4-dichlorophenyl)-1,1-dimethylurea. The thermosetting composition according to any one of claims 1 to 10, which contains a core-shell type rubber. The thermosetting composition according to claim 11, wherein the core-shell type rubber comprises acryl-butadiene core-shell rubber.