Modified spinnable phenolic resin as well as preparation method and application thereof

Abstract

The invention provides a preparation method of modified spinnable phenolic resin, which comprises the following steps: purifying phenolic resin, and removing free phenol and oligomer to obtain phenolic resin with low free phenol content; the preparation method comprises the following steps: adding phenolic resin with low free phenol content, a chain-shaped high-molecular polymer and an amine cross-linking agent into a stirring kettle, heating the stirring kettle in an inert gas atmosphere, heating the raw materials to a molten state, carrying out heat preservation stirring, cooling and slicing to obtain the modified spinnable phenolic resin. A chain-shaped high-molecular polymer is uniformly mixed into phenolic resin, and meanwhile, an amine cross-linking agent is added for further cross-linking, so that the molecular weight is increased, and the spinnability of a phenolic resin matrix is improved; the chain-shaped high-molecular polymer has very high strength, and the cross-linking agent and the chain-shaped high-molecular polymer are cross-linked to a certain degree to form a continuous phase or a semi-continuous phase in a phenolic resin matrix, so that the overall average molecular weight is improved, and obvious reinforcing and toughening effects are achieved. The invention further discloses the modified spinnable phenolic resin and application thereof.

Description

Technical Field

[0001] The invention belongs to the technical field of special resin modification, and in particular relates to a modified spinnable phenolic resin and a preparation method and application thereof. Background Art

[0002] At present, phenolic fiber is a three-dimensional cross-linked organic fiber with outstanding flame retardancy, heat insulation, high carbon residue rate, instantaneous high temperature resistance, chemical corrosion resistance and sound insulation. Phenolic fiber is generally prepared by melt spinning of thermoplastic phenolic resin to prepare raw fibers, and then heated and solidified in a mixed solution of acid and aldehyde to cross-link into insoluble and infusible fibers. The phenolic resin used is a low molecular weight chain polymer with a number average molecular weight of less than 1000. Unlike general polymer melt spinning, due to the small molecular weight and short molecular chain, the obtained resin raw fibers are very fragile and have extremely low strength. A slight disturbance can break the raw fibers and make them unable to be spun continuously. Therefore, the difficulty of spinning is much higher than that of general polymer resins. At the same time, the fragile raw fibers also bring many difficulties to various subsequent operations, and it is easy to cause broken fibers, broken fibers and hairy fibers if you are not careful.

[0003] Research on improving the spinnability of phenolic resin mainly focuses on two aspects. The first is to purify the phenolic resin and remove free phenol and oligomers. This method further purifies the phenolic resin, reduces the content of small molecules such as free phenol and oligomers, and improves the relative molecular weight of the resin and narrows the distribution range of the molecular weight to a limited extent. It can improve the spinnability of the phenolic resin raw material and the continuity of spinning to a certain extent, but it cannot fundamentally change the problems of low molecular weight, poor spinnability and low raw fiber strength of the phenolic resin raw material.

[0004] Another method is to carry out physical mixing modification, such as the phenolic resin in the relevant literature and the high molecular polymers such as cashew nut oil, polyamide, polyethylene and polyvinyl chloride are melt-mixed and then spun. This method can significantly improve the strength and operability of the resin precursor, but this method belongs to simple physical mixing, and there are problems such as poor uniformity between the modifier and the resin, and a large amount of the modifier mixed, and it will affect the comprehensive properties of the phenolic fiber products such as heat resistance and flame retardancy. The related art proposes to use cashew nut shell oil modified phenolic resin as raw material, and adopts melt spinning method to prepare cashew nut shell oil modified phenolic fiber. Cashew nut shell oil modified phenolic resin is polymerized by phenol, formaldehyde and cashew nut shell oil under the action of an acidic catalyst. This method modifies the raw material, and then obtains cashew nut shell oil modified phenolic fiber by melt spinning, which has complicated procedures and high production costs.

[0005] In order to solve the above technical problems, the present invention designs a modified spinnable phenolic resin and a preparation method and application thereof. Summary of the invention

[0006] The invention provides a modified spinnable phenolic resin and a preparation method and application thereof, aiming to solve the problems of poor spinnability of the phenolic resin and complicated modification process.

[0007] To achieve the above-mentioned purpose, the present invention provides the following technical scheme: a method for preparing a modified spinnable phenolic resin, comprising the following steps: purifying the phenolic resin, removing free phenol and oligomers, and obtaining a phenolic resin with a low free phenol content; adding the phenolic resin with a low free phenol content, a chain polymer and an amine cross-linking agent into a stirring kettle, heating the stirring kettle in an inert gas atmosphere, heating the raw materials to a molten state, stirring while keeping the temperature, and slicing after cooling to obtain the modified spinnable phenolic resin.

[0008] Based on the above technical solution, the chain-like high molecular polymer accounts for 1%-8% of the mass of the phenolic resin.

[0009] Based on the above technical scheme, the chain polymer is one or more of polybenzoate, polybutylene terephthalate, polyethylene terephthalic acid, vinyl acetate, polyvinyl formal, polyvinyl formal butyral, bismaleimide, para-hydroxyphenyl maleic anhydride imide, polybutylene terephthalate, polyamide, and polyphenylene ether.

[0010] Based on the above technical solution, the amine cross-linking agent accounts for 0.2%-2% of the mass of the phenolic resin.

[0011] The amine crosslinking agent is one or more of ethylenediamine, m-phenylenediamine, isophoronediamine, melamine, p-phenylenediamine, triethylamine, imidazole, and 2-methylimidazole.

[0012] Based on the above technical solution, the stirred tank is heated to 150-250° C. in an inert gas atmosphere.

[0013] Based on the above technical solution, the time of heat preservation and stirring is 0.5-3h.

[0014] Based on the above technical solution, the free phenol content of the phenolic resin with low free phenol content is less than or equal to 1.0%.

[0015] Based on the above technical solution, the inert gas is nitrogen.

[0016] In a second aspect, the present invention provides a modified spinnable phenolic resin, which is prepared according to the preparation method of the modified spinnable phenolic resin described in any one of the above embodiments.

[0017] In a third aspect, the present invention provides a modified spinnable phenolic resin obtained by the preparation method of the modified spinnable phenolic resin according to any one of the above embodiments, and its application in phenolic fiber materials.

[0018] Compared with the related art, the beneficial effects of the present invention are as follows: The present invention uniformly mixes the chain-like high molecular polymer into the phenolic resin by a physical mixing method, and simultaneously adds an amine cross-linking agent, so that the phenolic hydroxyl group in the phenolic resin reacts with the amino functional group in the cross-linking agent to generate a new CN bond, so that the molecules of the phenolic resin are further cross-linked, the molecular weight is increased, and the spinnability of the phenolic resin body is improved; in addition, the chain-like high molecular polymer itself has very high strength, and the amino functional groups in the cross-linking agent and the hydroxyl functional groups in the chain-like high molecular polymer are also cross-linked to a certain extent, forming a continuous phase or a semi-continuous phase in the phenolic resin matrix, thereby improving the overall average molecular weight and having an obvious strengthening and toughening effect. Compared with simple physical mixing and resin purification, the present invention has a more significant modification effect, can significantly improve the spinnability of the phenolic resin and the strength of the original silk obtained by spinning, and is simple, convenient and fast to operate. DETAILED DESCRIPTION

[0019] The following will combine the contents in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used in this specification includes any and all combinations of one or more of the related listed items.

[0021] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0022] Unless otherwise specified, the materials and reagents used in the following examples can be obtained from commercial sources.

[0023] The invention provides a preparation method of a modified spinnable phenolic resin, comprising the following steps: purifying the phenolic resin, removing free phenol and oligomers, and obtaining a phenolic resin with a low free phenol content; adding the phenolic resin with a low free phenol content, a chain high molecular polymer and an amine cross-linking agent into a stirring kettle, heating the stirring kettle in an inert gas atmosphere, heating the raw materials to a molten state, keeping the temperature and stirring, and slicing after cooling to obtain the modified spinnable phenolic resin.

[0024] The preparation method of the modified spinnable phenolic resin provided by the present invention is adopted. The chain-like high molecular polymer is uniformly mixed into the phenolic resin by a physical mixing method, and an amine cross-linking agent is added at the same time, so that the phenolic hydroxyl group in the phenolic resin reacts with the amino functional group in the cross-linking agent to generate a new CN bond, so that the molecules of the phenolic resin are further cross-linked, the molecular weight is increased, and the spinnability of the phenolic resin body is improved; in addition, the chain-like high molecular polymer itself has a very high strength, and the amino functional groups in the cross-linking agent are also cross-linked to a certain extent with the hydroxyl functional groups in the chain-like high molecular polymer, so as to form a continuous phase or a semi-continuous phase in the phenolic resin matrix, thereby improving the overall average molecular weight and having an obvious strengthening and toughening effect. Compared with simple physical mixing and resin purification, the method has a more significant modification effect, can significantly improve the spinnability of the phenolic resin and the strength of the raw silk obtained by spinning, and is simple, convenient and fast to operate.

[0025] Based on the above technical solution, the chain-like high molecular polymer accounts for 1%-8% of the mass of the phenolic resin.

[0026] Based on the above technical scheme, the chain polymer is one or more of polybenzoate, polybutylene terephthalate, polyethylene terephthalic acid, vinyl acetate, polyvinyl formal, polyvinyl formal butyral, bismaleimide, para-hydroxyphenyl maleic anhydride imide, polybutylene terephthalate, polyamide, and polyphenylene ether.

[0027] Based on the above technical solution, the amine cross-linking agent accounts for 0.2%-2% of the mass of the phenolic resin.

[0028] The amine crosslinking agent is one or more of ethylenediamine, m-phenylenediamine, isophoronediamine, melamine, p-phenylenediamine, triethylamine, imidazole, and 2-methylimidazole.

[0029] Based on the above technical solution, the stirred tank is heated to 150-250° C. in an inert gas atmosphere.

[0030] Based on the above technical solution, the time of heat preservation and stirring is 0.5-3h.

[0031] Based on the above technical solution, the free phenol content of the phenolic resin with low free phenol content is less than or equal to 1.0%.

[0032] Based on the above technical solution, the inert gas is nitrogen.

[0033] In a second aspect, the present invention provides a modified spinnable phenolic resin, which is prepared according to the preparation method of the modified spinnable phenolic resin described in any one of the above embodiments.

[0034] In a third aspect, the present invention provides a modified spinnable phenolic resin obtained by the preparation method of the modified spinnable phenolic resin according to any one of the above embodiments, and its application in phenolic fiber materials.

[0035] Embodiment 1: The purified phenolic resin with a free phenol content of 0.3% is placed in a sealed stirring kettle, and polybutylene terephthalate (6% by mass of the phenolic resin) and ethylenediamine (1% by mass of the phenolic resin) are added. After sealing, the kettle is heated to 190°C under the protection of nitrogen. After the phenolic resin is melted, the kettle is kept warm and stirred for 1 hour. The kettle is taken out, cooled, and sliced ​​to obtain a phenolic resin with high spinnability. The uncrosslinked raw yarn has a tensile strength of about 30 MPa and an elongation at break of 1.2% when melt-spun at 150°C.

[0036] Embodiment 2: The synthesis method of this embodiment is the same as that of Example 1, and the same parts are omitted. The difference from Example 1 is that the free phenol content of the phenolic resin is 0.2%, the chain polymer is polyethylene terephthalic acid whose mass is 3% of the mass of the phenolic resin and polybutylene terephthalate whose mass is 5% of the mass of the phenolic resin, the cross-linking agent is isophorone diamine whose mass is 1.2% of the mass of the phenolic resin, the heating temperature is 230°C, the heat preservation and stirring time is 2.5 hours, and a phenolic resin with high spinnability is obtained. After melt spinning at 180°C, the uncross-linked raw yarn has a tensile strength of about 50 MPa and an elongation at break of 1.6%.

[0037] Embodiment 3: The synthesis method of this embodiment is the same as that of Example 1, and the same parts are omitted. The difference from Example 1 is that the free phenol content of the phenolic resin is 0.6%, the chain high molecular polymer is vinyl acetate whose mass is 3% of the mass of the phenolic resin, the cross-linking agent is m-phenylenediamine whose mass is 0.3% of the mass of the phenolic resin, the heating temperature is 160°C, the insulation stirring time is 0.5 hour, and a phenolic resin with high spinnability is obtained. After melt spinning at 130°C, the tensile strength of the uncross-linked raw yarn is about 23 MPa, and the elongation at break is 0.8%.

[0038] Embodiment 4: The synthesis method of this embodiment is the same as that of Example 1, and the same parts are omitted. The difference from Example 1 is that the free phenol content of the phenolic resin is 1%, the chain high molecular polymer is 2% of the mass of the phenolic resin polyvinyl formal, 2% of polyamide and 2% of polyphenylene ether, the cross-linking agent is 2-methylimidazole, the mass of which is 0.8% of the mass of the phenolic resin, the heating temperature is 210°C, the insulation stirring time is 3 hours, and a phenolic resin with high spinnability is obtained. After melt spinning at 180°C, the tensile strength of the uncross-linked raw yarn is about 35 MPa, and the elongation at break is 1.3%.

[0039] Comparative Example 1: The purified phenolic resin with a free phenol content of 0.3% was directly melt-spun at 150°C, and the tensile strength of the uncrosslinked raw yarn was about 9 MPa and the elongation at break was 0.2%. Compared with the raw yarn obtained in Example 1, the tensile strength and elongation at break were significantly reduced.

[0040] Comparative Example 2: The synthesis method of this embodiment is the same as that of embodiment 2, and the same parts are omitted. The difference from embodiment 2 is that no crosslinking agent is added, and a phenolic resin with high spinnability is obtained. The uncrosslinked raw yarn is melt-spun at 180°C, and the tensile strength is about 20 MPa and the elongation at break is 0.5%. Compared with the raw yarn obtained in embodiment 2, the tensile strength and elongation at break are significantly reduced.

[0041] Comparative Example 3: The synthesis method of this embodiment is the same as that of embodiment 3, and the same parts are omitted. The difference from embodiment 3 is that no chain polymer is added, and a phenolic resin with high spinnability is obtained. The tensile strength of the uncrosslinked raw yarn is about 15 MPa and the elongation at break is 0.4% when melt-spun at 130°C. Compared with the raw yarn obtained in embodiment 3, the tensile strength and elongation at break are significantly reduced.

[0042] The present invention is described above by way of examples, but the present invention is not limited to the above specific embodiments, and any changes or modifications made based on the present invention belong to the scope of protection claimed by the present invention.

Claims

1. A method for preparing a modified spinnable phenolic resin, characterized in that: The following steps are involved: Purifying the phenolic resin to remove free phenol and oligomers to obtain a phenolic resin with a low free phenol content; Phenolic resin with low free phenol content, chain polymer and amine crosslinking agent are added into a stirring kettle, the stirring kettle is heated in an inert gas atmosphere, the raw materials are heated to a molten state, the mixture is stirred at the temperature, and the mixture is sliced ​​after cooling to obtain a modified spinnable phenolic resin.

2. The method for preparing the modified spinnable phenolic resin according to claim 1, characterized in that: The chain-like high molecular polymer accounts for 1%-8% of the mass of the phenolic resin.

3. The method for preparing the modified spinnable phenolic resin according to claim 1, characterized in that: The chain polymer is one or more of polybenzoate, polybutylene terephthalate, polyethylene terephthalic acid, vinyl acetate, polyvinyl formal, polyvinyl formal butyral, bismaleimide, p-hydroxyphenyl maleic anhydride imide, polybutylene terephthalate, polyamide, and polyphenylene ether.

4. The method for preparing the modified spinnable phenolic resin according to claim 1, characterized in that: The amine cross-linking agent accounts for 0.2%-2% of the mass of the phenolic resin.

5. The method for preparing the modified spinnable phenolic resin according to claim 1, characterized in that: The amine crosslinking agent is one or more of ethylenediamine, m-phenylenediamine, isophoronediamine, melamine, p-phenylenediamine, triethylamine, imidazole, and 2-methylimidazole.

6. The method for preparing the modified spinnable phenolic resin according to any one of claims 1 to 5, characterized in that: The stirred tank is heated to 150-250° C. in an inert gas atmosphere.

7. The method for preparing a modified spinnable phenolic resin according to any one of claims 1 to 5, characterized in that: The time of heat preservation and stirring is 0.5-3h.

8. The method for preparing the modified spinnable phenolic resin according to any one of claims 1 to 5, characterized in that: The free phenol content of the phenol-formaldehyde resin with low free phenol content is less than or equal to 1.0%.

9. A modified spinnable phenolic resin, characterized in that: The modified spinnable phenolic resin is prepared according to the preparation method of any one of claims 1 to 8.

10. Use of the modified spinnable phenolic resin obtained by the preparation method of the modified spinnable phenolic resin according to any one of claims 1 to 8 in phenolic fiber materials.