CN105885340B

CN105885340B - Antioxidant composition and modified polyformaldehyde resin composition and modified polyformaldehyde resin and preparation method thereof

Info

Publication number: CN105885340B
Application number: CN201510038129.6A
Authority: CN
Inventors: 孙小杰; 梁文斌; 马伊; 张寅灵; 赖世燿
Original assignee: Shenhua Group Corp Ltd; National Institute of Clean and Low Carbon Energy
Current assignee: China Energy Investment Corp Ltd; National Institute of Clean and Low Carbon Energy
Priority date: 2014-12-26
Filing date: 2015-01-26
Publication date: 2019-03-29
Anticipated expiration: 2035-01-26
Also published as: CN105885340A

Abstract

本发明提供了一种抗氧剂组合物和改性聚甲醛树脂组合物以及改性聚甲醛树脂及其制备方法。本发明提供的抗氧剂组合物含有异氰酸酯类化合物、吸醛剂和任选地自由基捕捉剂，其重量份分别为(2.1‑7)、(0.3‑2.5)、(0‑1)优选为(2.1‑5)、(0.5‑2)、(0‑0.3)。当将聚甲醛树脂采用上述抗氧剂组合物进行改性时，能够非常显著地提高聚甲醛树脂的热稳定性。The invention provides an antioxidant composition, a modified polyoxymethylene resin composition, a modified polyoxymethylene resin and a preparation method thereof. The antioxidant composition provided by the present invention contains an isocyanate compound, an aldehyde absorbing agent and optionally a free radical scavenger, and the weight parts thereof are respectively (2.1-7), (0.3-2.5), (0-1), preferably (2.1‑5), (0.5‑2), (0‑0.3). When the polyoxymethylene resin is modified with the above antioxidant composition, the thermal stability of the polyoxymethylene resin can be significantly improved.

Description

Antioxidant composition and modified polyformaldehyde resin composition and modified polyformaldehyde resin And preparation method thereof

Technical field

The present invention relates to a kind of antioxidant compositions, a kind of modified polyformaldehyde resin group containing the antioxidant composition Close object, a kind of preparation method of modified polyformaldehyde resin and the modified polyformaldehyde resin that is prepared by this method.

Background technique

Polyformaldehyde (POM) is due to special molecular structure, and thermal stability is poor, thus the thermostabilization of POM is at it Most important, most basic key technology during synthesis and processed and applied.POM is easy to happen heat effect during melt-processed It is acted on oxygen, molecule, which once generates free radicals, will occur chain rupture, and continuous piptonychia aldehyde reaction then occurs.And formaldehyde and Thermal decomposition process will be promoted by the micro formic acid that oxidation of formaldehyde generates again, greatly accelerate piptonychia aldehyde reaction, until big point of POM Subchain is decomposed totally.Antioxidant is the thermal oxidation stability auxiliary agent that polymer material is most important, most basic.Antioxidant is poly- by capturing It closes the free radical that objects system generates under heat effect, oxygen effect and reaches stable to interrupt whole system autoxidation cyclic process Purpose.Frequently with the phenolic antioxidant of Irganox259 and Irganox245 as antioxidant in domestic and international POM production application, Studies have shown that the kind antioxidant has significant thermostable effect to POM, the thermal stability of POM can be increased substantially, is suitable Improve the excellent antioxidant of the thermal oxidation stability performance of POM.But it in order to achieve the effect that preferable heat resistanceheat resistant oxygen effect, usually needs The antioxidant of larger dosage is wanted, and the price of this kind antioxidant is typically more expensive, therefore has become influence POM production cost One of principal element.

Summary of the invention

The purpose of the invention is to overcome the existing method of use to carry out the upper of thermal stability modification to acetal resin Defect is stated, and provides a kind of do not contain or only containing the antioxidant composition of conventional antioxidant, one kind on a small quantity containing described The modified polyformaldehyde resin composition of antioxidant composition, a kind of preparation method of modified polyformaldehyde resin and by party's legal system Standby obtained modified polyformaldehyde resin.

Specifically, antioxidant composition provided by the invention contain isocyanate ester compound, inhale aldehyde agent and optionally from By base agent for capturing, parts by weight are respectively (2.1-7), (0.3-2.5), (0-1), preferably (2.1-5), (0.5-2), (0- 0.3)。

Modified polyformaldehyde resin composition provided by the invention contains polyformaldehyde and above-mentioned antioxidant composition, specifically, The composition contains polyformaldehyde, isocyanate ester compound, suction aldehyde agent and optionally free radical scavenger, parts by weight are respectively 100, (2.1-7), (0.3-2.5), (0-1), preferably 100, (2.1-5), (0.5-2), (0-0.3).

The preparation method of modified polyformaldehyde resin provided by the invention include by above-mentioned modified polyformaldehyde resin composition in Melting extrusion is granulated at 180-225 DEG C, is then carried out and dry.

The present invention also provides modified polyformaldehyde resins prepared by the above method.

The present inventor by further investigation after find, when polyformaldehyde simultaneously use isocyanate ester compound and It inhales aldehyde agent and when optionally free radical scavenger is modified, the thermal stability of polyformaldehyde can be improved very significantly.Speculate Its reason, it may be possible to due to: on the one hand, the isocyanate ester compound in the antioxidant composition can not only remove poly- first Remaining lewis acid (lewis acidic residual is easy to cause polyformaldehyde to degrade) in urea formaldehyde, but also can be with polyformaldehyde Terminal hydroxy group directly reacts during melt extrusion, relatively stable amino methyl ester bond is generated, to acetal resin Central Plains Unstable end-group have and newly-generated is closed, to reduce the content of unstable end-group in acetal resin, is made It is with lower burst size of methanal and superior thermal stability；On the other hand, aldehyde agent and the free radical scavenger inhaled The conversion that can not only promote terminal hydroxy group in lewis acidic removing and acetal resin is added, but also can be improved system Antioxidant effect, to be very beneficial for the raising of acetal resin thermal stability.

A preferred embodiment of the invention, when the polyamide contained in the antioxidant composition is copolymerization acyl When amine, it is more advantageous to the raising of acetal resin thermal stability.

Other features and advantages of the present invention will the following detailed description will be given in the detailed implementation section.

Specific embodiment

Detailed description of the preferred embodiments below.It should be understood that described herein specific Embodiment is merely to illustrate and explain the present invention, and is not intended to restrict the invention.

Antioxidant composition provided by the invention contains isocyanate ester compound, inhales aldehyde agent and optionally radical-scavenging Agent, parts by weight are respectively (2.1-7), (0.3-2.5), (0-1), preferably (2.1-5), (0.5-2), (0-0.3).

The present invention is not particularly limited the type of the isocyanate ester compound, such as can be selected from diphenylmethyl Alkane -4,4 '-diisocyanate (MDI), 2,4 tolylene diisocyanate (TDI), paraphenylene diisocyanate (PPDI), oneself two isocyanides At least one of acid esters (HDI), isophorone diisocyanate (IPDI) and triphenylmethane triisocyanate.It is easy to get from raw material The angle of property is set out, and the isocyanate ester compound is particularly preferably 4,4 '-diisocyanate of diphenyl methane-and/or 2, 4- toluene di-isocyanate(TDI).

The antioxidant composition provided according to the present invention, the free radical scavenger are particularly preferably 2,2,6,6- tetramethyls Piperidines-nitrogen-oxide, 2,2- diphenyl -1- trinitrophenyl-hydrazine, 1,4-benzoquinone, tetramethyl-benzoquinone, N- tert-butyl-α-phenyinitrone At least one of with 3-2- (2- bromacetamido) acetamide] -2,2,5,5- tetramethyl -1- pyrrolidinyl oxide.From original Expect it is ready availability from the point of view of, the free radical scavenger is particularly preferably 2,2,6,6- tetramethyl piperidines-nitrogen-oxide (TEMPO)。

The antioxidant composition provided according to the present invention, the suction aldehyde agent are preferably selected from melamine and polyamide extremely Few one kind.

Wherein the polyamide can be existing various polyamide, for example, can be homopolymerization polyamide, or altogether Polyester-polyamide, preferably copolyamide.The present inventor has found after further investigation, when the polyamide is copolymerization When polyamide, the thermal stability of polyformaldehyde can be improved extremely significantly.The example of the equal polyester-polyamide includes but is not limited to: At least one of polyamide 6, polyamide 66, polyamide 610 etc..The example of the copolyamide includes but is not limited to: poly- At least one of amide PA6/12, polyamide PA10/10, polyamide 6/66/1010, polyamide 548, polyamide 6/66 etc..

The suction aldehyde agent is melamine and/or polyamide, when inhaling the mixture that aldehyde agent is melamine and polyamide, The parts by weight of melamine and polyamide are respectively (0.1-0.7), (0.2-1.8), preferably (0.3-0.5), (0.5-1.5)； When inhale aldehyde agent be melamine when, parts by weight be (0.3-2.5), preferably 0.5, it is highly preferred that the antioxidant group at this time It closes object and also contains free radical scavenger；When inhaling aldehyde agent is polyamide, the parts by weight of polyamide are (0.3-2.5), preferably (0.5-1.5), more preferably (0.5,1,1.4,1.5).Wherein, it is special for inhaling aldehyde agent for the mixture of polyamide and melamine Preferably.When containing polyamide and melamine simultaneously in the antioxidant composition, acetal resin can be made to obtain more Excellent thermal stability.When inhaling aldehyde agent is melamine, need that free radical scavenger is added into antioxidant composition.

The antioxidant composition provided according to the present invention, it is preferable that the antioxidant composition also contain antioxidant and/or Acid absorbent is more advantageous to further increasing for polyformaldehyde thermal stability in this way.

The present invention is not particularly limited the type and dosage of the antioxidant, for example, the antioxidant can be phenol At least one of kind antioxidant, amine antioxidants and phosphite ester antioxidant.Wherein, the example packet of the phenolic antioxidant It includes but is not limited to: 2- tert-butyl hydroquinone (antioxidant TBHQ), 1,3,5- trimethyl -2,4,6- (3,5- di-t-butyl -4- hydroxyl Base benzyl) benzene (antioxidant 1330), triethylene-glycol be bis- [β-(3- tertiary butyl-4-hydroxy -5- aminomethyl phenyl) propionic ester] (antioxidant 245), four [3- (3,5- di-tert-butyl-hydroxy phenyl) propionic acid] pentaerythritol esters (antioxidant 1010), 2,2 '-Asias At least one of methyl-bis- (4- methyl-6-tert-butylphenol) (antioxidant 2246s) etc..The example packet of the amine antioxidants It includes but is not limited to: N- (1,3- dimethylbutyl)-N '-diphenyl-para-phenylene diamine (antioxidant 4020), N- cumenyl-N '-phenyl At least one of p-phenylenediamine (antioxidant 4010NA), N- phenyl-2-naphthylamine (antioxidant D) etc..The phosphorous acid salt is anti- The example of oxygen agent includes but is not limited to: three (2,4- di-tert-butyl-phenyl) phosphite esters (irgasfos 168).In addition, when described anti- When oxygen agent composition contains antioxidant, the parts by weight of the antioxidant and isocyanate ester compound be respectively (0.1-1), (2.1-7), preferably (0.3-0.5), (2.1-5).

The present invention is not particularly limited the type of the acid absorbent, for example, the acid absorbent can be selected from hydroxide At least one of magnesium, calcium hydroxide, calcium stearate, odium stearate and magnesium stearate.In addition, when the antioxidant composition contains When having acid absorbent, the parts by weight of the acid absorbent and isocyanate ester compound respectively (0.2-1), (2.1-7), preferably (0.3-0.5)、(2.1-5)。

Modified polyformaldehyde resin composition provided by the invention contains polyformaldehyde and above-mentioned antioxidant composition.Relative to The polyformaldehyde of 100 parts by weight, resin combination of the invention contain each component of the antioxidant composition of aforementioned weight.

In the free radical scavenger, the type of isocyanate ester compound and polyamide and the antioxidant composition The type and dosage of remaining component have been described herein above, and therefore not to repeat here.

The preparation method of modified polyformaldehyde resin provided by the invention include by above-mentioned modified polyformaldehyde resin composition in Melting extrusion is granulated at 180-225 DEG C, is then dried.

The preparation method of the modified polyformaldehyde resin provided according to the present invention, this method are further preferably included in melting extrusion and make Before grain, first each component in the modified resin composition is uniformly mixed, is more advantageous to the acetal resin heat in this way The raising of stability.The step of melting extrusion is granulated usually can be in existing single screw extrusion machine or double screw extruder Middle progress.In addition, the condition of the drying, which generally includes dry temperature, to be 50-100 DEG C, the dry time can be 1- 10 hours.

The present invention will be described in detail by way of examples below.

Embodiment 1

The embodiment is for illustrating antioxidant composition and modified polyformaldehyde resin composition provided by the invention and changing Property acetal resin and preparation method thereof.

By 100 parts by weight of polyoxymethylene resins (being purchased from coal chemical industry branch company, Shenhua Ning Mei group, trade mark MC90G, similarly hereinafter), 2.1 parts by weight diphenyl methane -4,4 '-diisocyanate (MDI) (Alfa Aesar company, similarly hereinafter), 1 weight parts of polyamide PA6/12 (being purchased from Chemical Co., Ltd., EMS Switzerland, trade mark Grilamid, similarly hereinafter), 0.1 parts by weight antioxidant 2- tert-butyl pair Benzenediol (antioxidant TBHQ), 0.4 parts by weight three (2,4- di-tert-butyl-phenyl) phosphite ester (irgasfos 168), 0.4 parts by weight Melamine, 0.4 parts by weight magnesium hydroxide use vented twin-screw extruder melting extrusion to be granulated after evenly mixing, squeeze out temperature Degree is 180 DEG C -225 DEG C, and screw speed is 100 revs/min, 2 hours dry at 80 DEG C after granulation, obtains modified polyacetal tree Rouge G1.

Embodiment 2

By 100 parts by weight of polyoxymethylene resins, 4 parts by weight 2,4 tolylene diisocyanates (TDI), (it is purchased from Alfa Aesar Company, similarly hereinafter), 0.5 weight parts of polyamide PA6/12,0.05 parts by weight antioxidant 2- tert-butyl hydroquinone (antioxidant TBHQ), 0.25 parts by weight 1,3,5- trimethyl -2,4,6- (3,5- di-t-butyl -4- hydroxyphenylmethyl) benzene (antioxidant 1330), 0.3 parts by weight melamine, 0.3 parts by weight of calcium stearate use vented twin-screw extruder melting extrusion to make after evenly mixing Grain, extrusion temperature are 180 DEG C -225 DEG C, and screw speed is 100 revs/min, 2 hours dry at 80 DEG C after granulation, are changed Property acetal resin G2.

Embodiment 3

By 100 parts by weight of polyoxymethylene resins, 5 parts by weight diphenyl methanes -4,4 '-diisocyanate (MDI), 1.5 weight Part polyamide PA6/12,0.1 parts by weight antioxidant 2- tert-butyl hydroquinone (antioxidant TBHQ), 0.4 parts by weight 1,3,5- tri- Methyl -2,4,6- (3,5- di-t-butyl -4- hydroxyphenylmethyl) benzene (antioxidant 1330), 0.5 parts by weight melamine, 0.5 weight Amount part calcium stearate uses vented twin-screw extruder melting extrusion to be granulated after evenly mixing, and extrusion temperature is 180 DEG C -225 DEG C, screw speed is 100 revs/min, it is 2 hours dry at 80 DEG C after granulation, obtain modified polyformaldehyde resin G3.

Embodiment 4

By 100 parts by weight of polyoxymethylene resins, 4 parts by weight diphenyl methanes -4,4 '-diisocyanate (MDI), 0.3 weight Part 2,2,6,6- tetramethyl piperidine-nitrogen-oxide (TEMPO), bis- [β-(the tertiary fourths of 3- of 0.5 parts by weight antioxidant triethylene-glycol Base -4- hydroxy-5-methyl base phenyl) propionic ester] (antioxidant 245), 0.5 parts by weight melamine, 0.5 parts by weight calcium hydroxide is equal It is granulated after even mixing using vented twin-screw extruder melting extrusion, extrusion temperature is 180 DEG C -225 DEG C, and screw speed is It is 100 revs/min, 2 hours dry at 80 DEG C after granulation, obtain modified polyformaldehyde resin G4.

Embodiment 5

Modified polyformaldehyde resin is prepared according to the method for embodiment 1, unlike, by melamine with identical weight part Polyamide PA6/12 substitution, specifically, by 100 parts by weight of polyoxymethylene resins, 2.1 parts by weight diphenyl methane -4,4 '-two isocyanides Acid esters (MDI), 1.4 weight parts of polyamide PA6/12,0.1 parts by weight antioxidant 2- tert-butyl hydroquinone (antioxidant TBHQ), 0.4 parts by weight three (2,4- di-tert-butyl-phenyl) phosphite ester (irgasfos 168), 0.4 parts by weight magnesium hydroxide are after evenly mixing It being granulated using vented twin-screw extruder melting extrusion, extrusion temperature is 180 DEG C -225 DEG C, and screw speed is 100 revs/min, It is 2 hours dry at 80 DEG C after granulation, obtain modified polyformaldehyde resin G5.

Comparative example 1

The comparative example is used to illustrate the antioxidant composition and modified polyformaldehyde resin composition and modified poly- first of reference Urea formaldehyde and preparation method thereof.

By the bis- [β-(3- tert-butyl -4- hydroxyls of 100 parts by weight of polyoxymethylene resins, 0.5 parts by weight antioxidant triethylene-glycol Base -5- aminomethyl phenyl) propionic ester] (antioxidant 245), 0.5 parts by weight melamine, 0.5 parts by weight magnesium hydroxide uniformly mix Afterwards using vented twin-screw extruder melting extrusion be granulated, extrusion temperature be 180 DEG C -225 DEG C, screw speed be 100 turns/ Point, it is 2 hours dry at 80 DEG C after granulation, obtain reference modified polyformaldehyde resin DG1.

Comparative example 2

By 100 parts by weight of polyoxymethylene resins, 2 parts by weight diphenyl methanes -4,4 '-diisocyanate (MDI), 0.5 weight Part antioxidant four [β-(3,5- di-tert-butyl-hydroxy phenyl) propionic acid] pentaerythritol ester (antioxidant 1010), 0.5 parts by weight three Poly cyanamid, 0.5 parts by weight magnesium hydroxide use vented twin-screw extruder melting extrusion to be granulated after evenly mixing, extrusion temperature It is 180 DEG C -225 DEG C, screw speed is 100 revs/min, it is 2 hours dry at 80 DEG C after granulation, obtain reference modified polyacetal Resin DG2.

Test case

Test case is used to illustrate the test of modified polyformaldehyde resin performance.

(1) melt index:

By untreated acetal resin, the modified polyformaldehyde resin G1-G5 being prepared by embodiment 1-5 and by right The reference modified polyformaldehyde resin DG1-DG2 that ratio 1-2 is prepared is respectively according to method specified in GB/T 3682-2000 It is measured melt index, wherein test condition includes: that test temperature is 190 DEG C, load 2.16kg.Acquired results such as table 1 It is shown.

Respectively by untreated acetal resin, by the embodiment 1-5 modified polyformaldehyde resin G1-G5 being prepared and The reference modified polyformaldehyde resin DG1-DG2 being prepared by comparative example 1-2 melting extrusion three under 210 DEG C of extrusion temperature It is secondary, melt index then is measured according to method specified in GB/T 3682-2000 respectively, wherein test condition includes: test Temperature is 190 DEG C, load 2.16kg.Acquired results are as shown in table 1.

(2) thermal decomposition temperature:

Untreated acetal resin is measured, by embodiment using the thermal gravimetric analyzer (TGA) of German NETZSCH company The modified polyformaldehyde resin G1-G5 that 1-5 the is prepared and reference modified polyacetal DG1- being prepared by comparative example 1-2 Starting thermal decomposition temperature of the DG2 in nitrogen and air, temperature when decomposing 10% and thermal decomposition terminate temperature.Acquired results As shown in table 1.

(3) burst size of methanal:

Untreated acetal resin is detected using the TGA-MS instrument of German NETZSCH company, is prepared by embodiment 1-5 Obtained modified polyformaldehyde resin G1-G5 and the reference modified polyacetal DG1-DG2 being prepared by comparative example 1-2 are in nitrogen With burst size of methanal when being thermally decomposed in air, wherein ion stream current signal peak face when burst size of methanal=Form aldehyde release Product (A*s)/sample quality (mg).Acquired results are as shown in table 1.

The preferred embodiment of the present invention has been described above in detail, still, during present invention is not limited to the embodiments described above Detail within the scope of the technical concept of the present invention can be with various simple variants of the technical solution of the present invention are made, this A little simple variants all belong to the scope of protection of the present invention.

It is further to note that specific technical features described in the above specific embodiments, in not lance In the case where shield, it can be combined in any appropriate way.In order to avoid unnecessary repetition, the present invention to it is various can No further explanation will be given for the combination of energy.

In addition, various embodiments of the present invention can be combined randomly, as long as it is without prejudice to originally The thought of invention, it should also be regarded as the disclosure of the present invention.

Claims

1. a modified polyoxymethylene resin composition is characterized in that, this composition contains polyoxymethylene, isocyanate compound, aldehyde absorbing agent and optionally free radical scavenger, and its parts by weight are respectively 100, (2.1-7 ), (0.3-2.5), (0-1);

The aldehyde absorbing agent is melamine and/or polyamide, and the polyamide is a copolyamide;

When the aldehyde absorbing agent is melamine, the modified polyoxymethylene resin composition also contains a free radical scavenger;

The free radical scavenger is selected from 2,2,6,6-tetramethylpiperidine-nitrogen-oxide, 2,2-diphenyl-1-trinitrophenylhydrazine, p-benzoquinone, tetramethyl Benzoquinone, N-tert-butyl-α-phenylnitrone and 3-2-(2-bromoacetamido)acetamide]-2,2,5,5-tetramethyl-1-pyrrolidinyl oxide at least one of them.

2. The modified polyoxymethylene resin composition according to claim 1, wherein the weight parts of the polyoxymethylene, the isocyanate compound, the aldehyde absorbing agent and the radical scavenger are 100, (2.1-5), ( 0.5-2), (0-0.3).

3. The modified polyoxymethylene resin composition according to claim 1, wherein,

The isocyanate compound is selected from diphenylmethane-4,4'-diisocyanate, 2,4-diisocyanate tolyl, p-phenylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate and triphenylmethane at least one of triisocyanates.

4. The modified polyoxymethylene resin composition according to claim 1, wherein the polyamide is at least one of polyamide PA6/12, polyamide 6/66/1010, polyamide 548 and polyamide 6/66 A sort of.

5. The modified polyoxymethylene resin composition according to any one of claims 1-4, wherein,

When the aldehyde absorbing agent is a mixture of melamine and polyamide, relative to 100 parts by weight of polyoxymethylene, the weight parts of melamine and polyamide are (0.1-0.7) and (0.2-1.8) respectively;

When the aldehyde absorbing agent is melamine, its weight part is (0.3-2.5) relative to 100 parts by weight of polyoxymethylene;

When the aldehyde absorbing agent is polyamide, the weight part of polyamide relative to 100 weight parts of polyoxymethylene is (0.3-2.5).

6. The modified polyoxymethylene resin composition according to claim 5, wherein, when the aldehyde absorbing agent is a mixture of melamine and polyamide, relative to 100 parts by weight of polyoxymethylene, the parts by weight of melamine and polyamide are respectively (0.3-0.5), (0.5-1.5).

7 . The modified polyoxymethylene resin composition according to claim 5 , wherein when the aldehyde absorbing agent is melamine, its weight part is 0.5 with respect to 100 weight parts of polyoxymethylene. 8 .

8 . The modified polyoxymethylene resin composition according to claim 5 , wherein when the aldehyde absorbing agent is polyamide, the weight part of polyamide is 0.5-1.5 with respect to 100 weight parts of polyoxymethylene. 9 .

9 . The modified polyoxymethylene resin composition according to claim 8 , wherein, when the aldehyde absorbing agent is polyamide, the weight parts of polyamide relative to 100 parts by weight of polyoxymethylene are 0.5, 1, 1.4, and 1.5. 10 . .

10. The modified polyoxymethylene resin composition according to any one of claims 1-4, wherein the modified polyoxymethylene resin composition further contains an antioxidant and/or an acid absorbing agent, and relative to 100 weight parts of polyoxymethylene, its weight parts are respectively (0.1-1), (0.2-1);

The antioxidant is selected from at least one of phenolic antioxidants, amine antioxidants and phosphite antioxidants.

11. The modified polyoxymethylene resin composition according to claim 10, wherein, relative to 100 parts by weight of polyoxymethylene, the weight parts of antioxidant and acid absorbing agent are (0.3-0.5) and 0.5, respectively.

12. The modified polyoxymethylene resin composition according to any one of claims 1-4, wherein, when the modified polyoxymethylene resin composition contains an antioxidant, relative to 100 parts by weight of polyoxymethylene, the The weight parts of the antioxidant and the isocyanate compound are respectively (0.1-1) and (2.1-7);

13. The modified polyoxymethylene resin composition according to claim 12, wherein, relative to 100 parts by weight of polyoxymethylene, the weight parts of the antioxidant and the isocyanate compound are respectively (0.3-0.5), (2.1 -5).

14. The modified polyoxymethylene resin composition according to any one of claims 1-4, wherein, when the modified polyoxymethylene resin composition contains an acid absorbing agent, relative to 100 parts by weight of polyoxymethylene, the The weight parts of the acid absorbing agent and the isocyanate compound are respectively (0.2-1) and (2.1-7).

15. The modified polyoxymethylene resin composition according to claim 14, wherein the weight parts of the acid absorbing agent and the isocyanate compound are (0.3-0.5) and (2.1-5), respectively.

16. The modified polyoxymethylene resin composition according to claim 14, wherein the acid absorbing agent is selected from the group consisting of magnesium hydroxide, calcium hydroxide, calcium stearate, sodium stearate and magnesium stearate. at least one.

17. A method for preparing a modified polyoxymethylene resin, the method comprising melting, extruding and granulating the modified polyoxymethylene resin composition according to any one of claims 1-16 at 180-225° C., followed by drying .

18. The modified polyoxymethylene resin prepared by the method of claim 17.