Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G16/00—Condensation polymers of aldehydes or ketones with monomers not provided for in the groups C08G4/00 - C08G14/00
  • C08G16/02—Condensation polymers of aldehydes or ketones with monomers not provided for in the groups C08G4/00 - C08G14/00 of aldehydes
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
  • C08J5/24—Impregnating materials with prepolymers which can be polymerised in situ, e.g. manufacture of prepregs

Definitions

• the present invention relates to a furan resin, a resin composition, and a method for producing a furan resin. More specifically, the present invention relates to a furan resin, a resin composition containing a furan resin, a prepreg in which a fiber substrate is impregnated with a resin composition containing a furan resin, a panel using the prepreg, a cured product of a resin composition containing a furan resin, and a method for producing a furan resin.
• Furan resin is a curable resin containing a furan ring, and is known to be synthesized by the self-condensation reaction of furfuryl alcohol or the condensation reaction of furfuryl alcohol with aldehydes and/or phenols.
• Patent Document 1 discloses a method for producing a copolymer of furfuryl alcohol and formaldehyde. It discloses a dissolution step in which paraformaldehyde is added to furfuryl alcohol and stirred under alkaline conditions at a heating temperature not exceeding 100°C to dissolve the paraformaldehyde in the furfuryl alcohol, and a polymerization step in which an acid catalyst is added to the solution obtained in the dissolution step to polymerize it.
• formaldehyde scavengers include urea, acetamide, methylacetamide, dimethylurea, and toluenesulfonamide.
• Patent Documents 1 and 2 leave room for improvement in terms of improving the flame retardancy of furan resin.
• FT-IR Fourier transform infrared spectroscopy
• a resin composition comprising the furan resin according to [1] or [2].
• a resin composition comprising the furan resin according to [1] or [2], the resin composition being in the form of a film.
• Step 1 of mixing furfuryl alcohol, an acid catalyst, and aldehydes at room temperature, dissolving the mixture by heating to a pH of 4 or less, and then allowing a polymerization reaction between the furfuryl alcohol and the aldehydes to proceed; a step 2 of obtaining a polymer by removing the remaining furfuryl alcohol monomer and aldehyde monomer under a condition where the polymerization reaction is suppressed by adding a neutralizing agent; Step 3: adding urea to react with the polymer;
• a method for producing a furan resin comprising: [9] The method for producing a furan resin according to [8], In the step 1, the heating temperature is 80°C or higher.
• step 2 In the method for producing a furan resin according to [8] or [9], the remaining furfuryl alcohol monomer and the aldehyde monomer are removed by vacuum distillation. [11] In the method for producing a furan resin according to any one of [8] to [10], The method for producing a furan resin, wherein the step 1 is carried out under atmospheric pressure.
• the present invention provides a furan resin that can improve flame retardancy.
• FIG. 1 is a diagram showing the FT-IR spectrum of the furan resin of Example 1.
• FIG. 1 is a diagram showing the FT-IR spectrum of the furan resin of Example 2.
• FIG. 1 shows the FT-IR spectrum of the furan resin of Example 3.
• FIG. 1 is a diagram showing the FT-IR spectrum of the furan resin of Comparative Example 1.
• FIG. 1 is a diagram showing the FT-IR spectrum of the furan resin of Comparative Example 2.
• FIG. 1 is a diagram showing the FT-IR spectrum of the furan resin of Comparative Example 3.
• a to b in the description of a numerical range means greater than or equal to a and less than or equal to b, unless otherwise specified.
• “1 to 5% by mass” means “greater than or equal to 1% by mass and less than or equal to 5% by mass.”
• the furan resin of this embodiment is a novel resin that satisfies the following condition (a).
• this resin will also be referred to as "furan resin (A).”
• furan resin (A) that can improve flame retardancy.
• Conventional furan resins use urea to capture formaldehyde used in their synthesis, but the urea is simply mixed with the furan resin without forming a chemical bond, and the urea does not enter the crosslinked structure even after curing.
• the furan resin (A) of the present embodiment satisfies condition (a) and incorporates urea into the cured product. That is, in the present embodiment, urea enters the crosslinked structure of the furan resin, and nitrogen is released during combustion to generate inert gas, thereby suppressing oxidative decomposition. This is thought to result in improved flame retardancy compared to conventional furan resins.
• the range of 1545 cm ⁇ 1 to 1560 cm ⁇ 1 is preferably 1553 cm ⁇ 1 to 1559 cm ⁇ 1
• the range of 1645 cm ⁇ 1 to 1662 cm ⁇ 1 is preferably 1646 cm ⁇ 1 to 1660 cm ⁇ 1 .
• the furan resin and the aqueous solution of paratoluenesulfonic acid (PTSA) may be mixed by any method as long as they are mixed uniformly, and they may be mixed by hand using a spatula or disposable chopsticks.
• the furan resin can be cured by treating the mixture for 1 hour at 120° C.
• the heating method is not particularly limited, but the mixture may be dropped onto an aluminum cup and cured in a dryer set at 120° C.
• the pulverization method may be any method that allows the FT-IR measurement to be performed appropriately, and a hammer, a mortar, or the like may be used.
• R1/R2 > 1.000, preferably R1/R2 > 1.003, and more preferably R1/R2 > 1.005.
• Furan resin (A) that satisfies condition (a) can be produced by adjusting its production method. Details will be described later, but one example is a method in which urea is reacted with a furan resin (polymer) obtained by polymerization.
• the mass average molecular weight (Mw) of the furan resin (A) is preferably 300 to 2,000, more preferably 500 to 1,800, and even more preferably 700 to 1,500.
• the mass average molecular weight of the furan resin (A) can be determined by gel permeation chromatography (GPC) measurement using polystyrene as the standard substance.
• the viscosity of the furan resin (A) at 25° C. is preferably 200 to 1500 mPa ⁇ s, more preferably 500 to 800 mPa ⁇ s.
• the viscosity of the furan resin (A) at 25°C can be measured, for example, using a RE-85 type viscometer manufactured by Toyo Sangyo.
• the method for producing the furan resin (A) includes the following steps 1 to 3.
• Step 1 Mixing furfuryl alcohol, an acid catalyst, and aldehydes at room temperature, heating and dissolving the mixture to a pH of 4 or less, and then allowing the polymerization reaction between the furfuryl alcohol and the aldehydes to proceed.
• Step 2 Adding a neutralizing agent to suppress the polymerization reaction, and removing the remaining furfuryl alcohol monomer and aldehyde monomer to obtain a polymer.
• Step 3 Adding urea to react with the polymer.
• Step 1 is a step of mixing furfuryl alcohol, an acid catalyst, and aldehydes at room temperature, dissolving the mixture by heating to a pH of 4 or less, and then allowing the furfuryl alcohol and the aldehydes to undergo a polymerization reaction. That is, since furfuryl alcohol is a liquid, the acid catalyst is a solid, and paraformaldehyde is a solid, they are heated and dissolved to obtain a mixed solution in order to mix them uniformly.
• the pH (25°C) of the mixed solution (polymerization solution) having a pH of 4 or less is 4 or less, and preferably 2.3 to 3.8. By adjusting the pH (25°C) of the mixed solution to 4 or less, the polymerization rate can be increased.
• the pH (25°C) of the mixed solution is controlled by adjusting the amount of acid catalyst added, for example.
• Furfuryl alcohol and the acid catalyst may be mixed in advance, or the acid catalyst may be further added after paraformaldehyde is added and mixed with furfuryl alcohol.
• the heating temperature in step 1 is preferably 80°C or higher, more preferably 90°C or higher, even more preferably 100°C or higher, and particularly preferably 110°C or higher, in order to obtain a homogeneous mixed solution and promote polymerization.
• the heating temperature is preferably 130°C or lower, and more preferably 120°C or lower, from the viewpoint of preventing unreacted formaldehyde from volatilizing and sublimating, adhering to the reflux tube, and clogging it, thereby suppressing separation and the generation of unreacted substances.
• the heating in step 1 may be carried out in two stages.
• the temperature in the first stage, the temperature may be maintained at a constant value in the range of 80°C or higher and less than 110°C, and then the temperature may be increased, and in the second stage, the temperature may be maintained at a constant value in the range of 110°C or higher and 130°C or lower.
• the temperature setting can be set appropriately depending on the degree of paraform evaporation and dissolution.
• the acid catalyst can be an inorganic acid or an organic acid.
• inorganic acids such as phosphoric acid, sulfuric acid, hydrochloric acid, xylenesulfonic acid, and paratoluenesulfonic acid
• organic acids such as acetic acid, lactic acid, succinic acid, glutaric acid, levulinic acid, crotonic acid, and adipic acid. These may be used alone or in combination of two or more. Of these, organic acids are preferred, and adipic acid is more preferred.
• the amount of acid catalyst added is preferably 0.1 to 10 parts by mass, more preferably 0.2 to 7 parts by mass, and even more preferably 0.3 to 5 parts by mass, per 100 parts by mass of furfuryl alcohol.
• the aldehydes are not particularly limited as long as they can release formaldehyde under the reaction conditions, but preferred examples include a 30 to 50% aqueous formaldehyde solution, trioxymethylene, and paraformaldehyde, with paraformaldehyde being particularly preferred.
• Furfuryl alcohol is reacted with an aldehyde, and the amount of the aldehyde used per mole of furfuryl alcohol is preferably 0.8 mole or more, more preferably 0.9 to 3.0 moles, and even more preferably 1.0 to 2.5 moles.
• the molar ratio By setting the molar ratio to 0.9 or more, the content of remaining furfuryl alcohol can be reduced, while by setting the molar ratio to 3.0 or less, it is possible to prevent excess aldehydes from precipitating in the reflux tube and clogging the reflux tube.
• Step 1 is preferably carried out without heating, for example, at an ambient temperature of 15 to 30°C.
• Step 1 is preferably carried out under atmospheric pressure (air, normal pressure).
• the mixing method is not particularly limited, and any known method can be used.
• the mixing time is not particularly limited, and may be, for example, 0.1 to 3 hours.
• the manufacturing method of this embodiment does not include the step of adding paraformaldehyde to furfuryl alcohol and dissolving the paraformaldehyde in furfuryl alcohol under alkaline conditions prior to step 1.
• Step 2 is a step in which the remaining furfuryl alcohol monomer and aldehyde monomer are removed to obtain a polymer in a state in which the polymerization reaction is suppressed by adding a neutralizing agent.
• the polymerization reaction can be suppressed by neutralizing the reaction mixture by adding a neutralizing agent.
• the amount of neutralizing agent added should be such that the pH of the polymerization solution exceeds 4, but the pH is preferably 4.5 or higher, and more preferably 5 to 7.
• Neutralizing agents include bases such as sodium hydroxide, potassium hydroxide, and ammonia.
• the polymerization liquid to which the neutralizing agent has been added may be distilled under reduced pressure. This makes it possible to remove the furfuryl alcohol and aldehydes that remain unpolymerized.
• Water can be gradually added to the system during vacuum distillation, allowing furfuryl alcohol and formaldehyde to be efficiently removed by steam distillation.
• alcohol-based solvents such as methanol or ethanol, ketone-based solvents such as acetone or MIBK, or hydrocarbon-based solvents such as hexane or heptane can be used instead of water. Only one of these may be used, or two or more may be used.
• Step 3 is a step of adding urea and reacting it with the polymer. As a result, urea is incorporated into the polymer, and a furan resin (A) can be obtained. Whether or not urea has reacted with the polymer can be confirmed by FT-IR of the cured product of the furan resin (A).
• the reaction temperature is preferably 40°C or higher, more preferably 45°C or higher, while it is preferably 70°C or lower, more preferably 60°C or lower.
• the reaction time for step 3 is set appropriately taking into account temperature conditions, etc., but can be approximately 0.5 to 3 hours.
• Step 3 is preferably carried out under atmospheric pressure (air, normal pressure).
• the furan resin (A) can be obtained.
• the resulting furan resin (A) may be diluted with water or a solvent to reduce its viscosity, for example, to improve its ability to impregnate glass cloth, etc.
• the solvent include one or more solvents selected from alcohol solvents such as methanol, ethanol, and isopropyl alcohol; acetone; and acetone derivatives such as methyl isobutyl ketone (MIBK).
• the resin composition of the present embodiment contains a furan resin (A), which can improve the flame retardancy of a molded article made using the resin composition.
• the resin composition preferably contains an acid catalyst in order to effectively cure the furan resin (A).
• the acid catalyst include those similar to those listed in the above step 1. Among them, inorganic acids such as phosphoric acid, sulfuric acid, hydrochloric acid, xylenesulfonic acid, and paratoluenesulfonic acid are preferred.
• the resin composition may contain known compounds depending on the application.
• known compounds include curable resins other than the furan resin (A), thermoplastic resins, curing agents, curing accelerators, coupling agents, fillers, reinforcing fibers, elastomers, pigments, flame retardants, adhesion promoters, and other additives. Only one of these may be contained, or two or more may be contained.
• coupling agent examples include silane coupling agents such as vinyl silane coupling agents, epoxy silane coupling agents, cationic silane coupling agents, and amino silane coupling agents, titanate coupling agents, and silicone oil coupling agents, etc. Only one type of coupling agent may be used, or two or more types may be used.
• Specific compounds of the silane coupling agent include, for example, 3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-(2aminoethyl)-3-aminopropyl-silanol, ⁇ -aminopropyltriethoxysilane, ⁇ -aminopropyltrimethoxysilane, N- ⁇ (aminoethyl) ⁇ -aminopropyltrimethoxysilane, N- ⁇ (aminoethyl) ⁇ -aminopropylmethyldimethoxysilane, N-phenyl ⁇ -aminopropyltriethoxysilane, N-phenyl ⁇ -aminopropyltrimethoxysilane, N- ⁇ (aminoe
• the leveling agent is preferably used in an amount of 2% by mass or less, and more preferably in an amount of 0.01% by mass or more and 1.0% by mass or less, based on the total amount of the resin composition.
• the resin composition of this embodiment may contain water or a solvent (such as an organic solvent), and the solvent may be selected depending on the application.
• the furan resin (A) may be diluted with water or a solvent such as methanol to reduce viscosity.
• the resin composition of this embodiment may be substantially free of a solvent (such as an organic solvent).
• the resin composition of the present embodiment can be produced by mixing the above components by a known method.
• the solids content of the resin composition may be, for example, 30% by mass or more and 90% by mass or less, and more preferably 40% by mass or more and 85% by mass or less. This results in a resin composition with excellent workability and film-forming properties.
• the varnish-like resin composition can be prepared by mixing and stirring the above-mentioned components using various mixers, such as those used in ultrasonic dispersion, high-pressure collision dispersion, high-speed rotation dispersion, bead mill dispersion, high-speed shear dispersion, and rotation-revolution dispersion.
• various mixers such as those used in ultrasonic dispersion, high-pressure collision dispersion, high-speed rotation dispersion, bead mill dispersion, high-speed shear dispersion, and rotation-revolution dispersion.
• the resin composition can be cured and used suitably for molded articles, which will be described later.
• the resin composition can also be used as an impregnation or binder, in which it is used by impregnating various substrates such as organic fibers, metals, and glass.
• the resin film of this embodiment can be obtained by forming the resin composition in a varnish form into a film.
• the resin film is preferably in a B-stage (semi-cured) state.
• the resin film of this embodiment can be obtained by removing the solvent and water from a coating film obtained by applying a varnish-like resin composition.
• the solvent and water content can be 5% by mass or less based on the entire resin film.
• the solvent removal step can be carried out, for example, at 60°C to 110°C for 5 to 30 minutes. This allows for sufficient removal of the solvent and water while suppressing the progress of curing of the furan resin (A).
• the resin film of this embodiment may consist solely of a resin film, or may be configured to include a fiber substrate inside.
• the method for impregnating the fiber substrate with the resin composition is not particularly limited, but examples include a method of immersing the fiber substrate in the resin varnish, a method of applying the resin varnish to the fiber substrate using various coaters, a method of spraying the resin varnish onto the fiber substrate, and a method of laminating both sides of the fiber substrate with the resin film made of the resin composition.
• the fiber substrate examples include glass fiber substrates such as woven glass cloth and non-woven glass cloth; inorganic fiber substrates such as woven or non-woven cloth made from inorganic compounds other than glass; and organic fiber substrates made from organic fibers such as aromatic polyamideimide resin, polyamide resin, aromatic polyester resin, polyester resin, polyimide resin, and fluororesin.
• glass fiber substrates typified by woven glass cloth, in terms of strength, can improve the mechanical strength and heat resistance of the printed wiring board.
• the thickness of the fiber substrate is not particularly limited, but is preferably 50 ⁇ m to 350 ⁇ m, more preferably 70 ⁇ m to 300 ⁇ m, and even more preferably 90 ⁇ m to 270 ⁇ m. Use of a fiber substrate having such a thickness can further improve the handleability during prepreg production. When the thickness of the fiber substrate is equal to or less than the upper limit, the impregnation of the resin composition into the fiber substrate is improved, and the occurrence of strand voids and a decrease in insulation reliability can be suppressed. On the other hand, when the thickness of the fiber substrate is equal to or more than the lower limit, the strength of the prepreg using the fiber substrate can be improved.
• glass fiber substrate for example, a glass fiber substrate formed from one or more types of glass selected from E glass, S glass, D glass, T glass, NE glass, UT glass, L glass, HP glass, and quartz glass is preferably used.
• the thickness of the prepreg is not particularly limited, but is preferably 50 ⁇ m to 400 ⁇ m, more preferably 70 ⁇ m to 350 ⁇ m, and even more preferably 90 ⁇ m to 320 ⁇ m.
• the prepreg is then fully cured and can be used to make panels suitable for use as wall and ceiling materials in buildings and transportation equipment.
• B stage refers to a state in which 5-90% of the resin composition has cured (semi-cured), while C stage refers to a state in which over 90% of the resin composition has cured (fully cured).
• the degree of curing can be confirmed by immersing the resin in methanol to dissolve the uncured resin, then drying and measuring the weight.
• the molded article of the present embodiment is made using a cured product of the resin composition and is suitable for applications requiring flame retardancy, such as transportation equipment such as automobiles, aircraft, railroad vehicles, and ships, and various parts and structural members for buildings, office equipment, general-purpose machines, household electrical appliances, and electrical equipment.
• Embodiments of the present invention will be described in detail based on examples and comparative examples. Note that the present invention is not limited to the examples.
• Example 2 Furfuryl alcohol, paraform (92%), and adipic acid were charged into a reaction vessel at room temperature and atmospheric pressure in the amounts (parts by mass) shown in Table 1, and the temperature was raised to 105°C while stirring. After 5 hours and 40 minutes, it was confirmed that the paraform and adipic acid had dissolved and formed a homogeneous solution, and the pH was measured and confirmed to be 3.1 (25°C). The temperature was then raised to 117°C ⁇ 3°C and the reaction was continued for 5 hours and 25 minutes, until the viscosity reached 311 mPa ⁇ s. Cooling was initiated when the temperature reached 100°C or below, and 25% aqueous potassium hydroxide solution was added for neutralization.
• the pH at this time was 5.6 (25°C).
• the pressure inside the reaction vessel was reduced to 80 torr while the temperature was raised, and the mixture was heated at 140°C and 80 torr for 1 hour. After cooling to 100°C, water was added. Water-1 and urea were then added in the amounts shown in Table 1, and the reaction was continued at 55°C. Finally, water-2 was added to adjust the viscosity to that shown in Table 1, to obtain furan resin (A-2).
• Example 3 Furfuryl alcohol, paraform (92%), and adipic acid were charged into a reaction vessel at room temperature and atmospheric pressure in the amounts (parts by mass) shown in Table 1, and the temperature was raised to 100°C while stirring. After confirming that the paraform and adipic acid had dissolved and formed a homogeneous solution in 9 hours and 20 minutes, the pH was measured and confirmed to be 3.1 (25°C). The temperature was then raised to 117°C ⁇ 3°C and the reaction was continued for 7 hours and 15 minutes until the viscosity reached 302 mPa ⁇ s. Cooling was initiated, and once the temperature had dropped below 100°C, 25% aqueous potassium hydroxide solution was added for neutralization. The pH at this time was 5.6 (25°C).
• ⁇ Measurement conditions 10 g of each furan resin was mixed with 0.33 g of a 55% aqueous solution of paratoluenesulfonic acid (PTSA) to obtain a mixture, which was then treated at 120°C for 1 hour and pulverized to prepare a sample.
• the IR spectrum of the sample was measured using Fourier transform infrared spectroscopy (FT-IR).
• FT-IR Fourier transform infrared spectroscopy
• the transmittance of the maximum absorption peak in the range of 1545 cm ⁇ 1 to 1560 cm ⁇ 1 was defined as R1
• the transmittance of the maximum absorption peak in the range of 1645 cm ⁇ 1 to 1662 cm ⁇ 1 was defined as R2.
• Fourier transform infrared spectroscopic analysis measuring device FT-IR Nicolect iS20 manufactured by Thermo Scientific was used, and was performed by the single reflection ATR method.
• Prepreg Test pieces measuring 125 mm in length, 13 mm in width, and 1.2 mm in thickness were prepared from the obtained prepreg, and measurements were made in accordance with the UL94 vertical flame test (a standard established by Under Writers Laboratories Inc., USA). Specifically, with the test piece held perpendicular to the length direction, a flame was applied from below the test piece for 10 seconds, and the burning time (t1 (seconds)) from removing the flame until the flame went out was measured. Once the flame went out, the flame was applied again for 10 seconds, and the burning time (t2 (seconds)) from removing the flame until the flame went out was measured, and the test piece was evaluated based on the following criteria.
• V-0 At least one of t1 and t2 is 10 seconds or less and (t1 + t2) ⁇ 50 seconds
• V-1 At least one of t1 and t2 is 30 seconds or less and (t1 + t2) ⁇ 250 seconds

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