CN116209689B - Process for producing polyacetal copolymer - Google Patents
Process for producing polyacetal copolymer Download PDFInfo
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- CN116209689B CN116209689B CN202180064966.XA CN202180064966A CN116209689B CN 116209689 B CN116209689 B CN 116209689B CN 202180064966 A CN202180064966 A CN 202180064966A CN 116209689 B CN116209689 B CN 116209689B
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- polyacetal copolymer
- molecular weight
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- 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
- C08G2/00—Addition polymers of aldehydes or cyclic oligomers thereof or of ketones; Addition copolymers thereof with less than 50 molar percent of other substances
- C08G2/18—Copolymerisation of aldehydes or ketones
Abstract
The purpose of the present invention is to provide: a method for producing a polyacetal copolymer, which can improve the appearance of a molded article made of a polyacetal copolymer and can reduce the fluctuation of the molded article for each article without changing special equipment for the conventional production process. The object of the present invention is achieved as follows. A process for producing a polyacetal copolymer, wherein a polyacetal copolymer is continuously produced by using trioxane as the main monomer (a), a cyclic methylal having at least one carbon-carbon bond as the comonomer (b), and at least 1 polymerization initiator (c) selected from a proton acid and a Lewis acid and a molecular weight regulator (d), wherein the supply amount of the molecular weight regulator (d) is periodically varied and supplied, and wherein P/T is 0.3 to 3 when the time of 1 period of the variation is P minutes and the average residence time in the polymerization reactor is T minutes.
Description
Technical Field
The present invention relates to: a simple method for producing a polyacetal copolymer of a molded article excellent in surface appearance.
Background
Conventionally, as a method for producing a polyacetal copolymer, there has been known: cationic copolymerization of trioxane as main monomer and cyclic ether and/or cyclic methylal having at least one carbon-carbon bond as comonomer. As the cationic initiator used in these copolymerization, various kinds of materials such as lewis acid and protonic acid are known.
Industrially, ventilation uses: and a continuous polymerization apparatus for supplying the main monomer, the comonomer and the initiator from one end of the polymerization apparatus and discharging the polyacetal copolymer as powder from the other end.
At this time, an appropriate amount of the molecular weight regulator is supplied together with the main monomer, the comonomer, and the initiator.
After purification of the polyacetal copolymer thus obtained, stabilizers/additives are compounded and commercialized.
Polyacetal copolymers are excellent in balance among mechanical properties, chemical resistance, slidability, etc., and are easy to process, and thus are widely used as typical process plastics, mainly in electric/electronic parts and other various mechanical parts of automobile parts.
In recent years, with the expansion of the use range, the use of thin-walled members is often seen. Although polyacetal copolymers are excellent in flowability and moldability, there are cases where surface roughness due to flow failure in a thin wall portion of a molded article, poor filling of a cavity end portion, and the like occur, and the appearance failure of the molded article significantly reduces its commercial value, which is a serious problem. The design of the molding die and the adjustment of the molding conditions are used gradually, but they are insufficient.
In view of this, as a countermeasure from the polymerization surface, a method of increasing a molecular weight regulator and increasing a melt index at the time of polymerization of a polyacetal copolymer has been proposed. However, these methods have resulted in a decrease in mechanical properties, particularly in impact resistance, and therefore have not yielded preferable results, and further improvement thereof has been demanded.
Japanese patent application laid-open No. Sho 50-30949 (patent document 1) describes the following method: by using a mixture of two-component polyacetal copolymers having different melt indices, the load dependence of melt viscosity is increased, or the viscosity at the time of molding is low and the viscosity after injection is high, and therefore the surface state of the molded article is improved.
Japanese patent application laid-open No. 11-12337 (patent document 2) describes the following bulk polymerization method: after the polymerization is started, the whole or the remaining part of the molecular weight regulator is supplied in the stage 1 or 2 or more of the subsequent stage. Improving the surface fluidity and filling degree during molding, and achieving good appearance and keeping impact resistance.
However, these methods require a large amount of blending steps of polyacetal copolymers and precise improvement of polymerization equipment, and there are industrial fluctuations of each product, which is not easy to implement.
Prior art literature
Patent literature
Patent document 1: japanese patent laid-open No. 50-30949
Patent document 2: japanese patent laid-open No. 11-12337
Disclosure of Invention
Problems to be solved by the invention
The purpose of the present invention is to provide: a method for producing a polyacetal copolymer, which can improve the appearance of a molded article made of a polyacetal copolymer and can reduce the fluctuation of the molded article for each article without changing special equipment for the conventional production process.
Solution for solving the problem
The present inventors have conducted intensive studies to achieve the above object, and as a result, found that: the above object can be achieved by periodically varying the molecular weight regulating dose supplied to the continuous polymerization apparatus, and the present invention has been completed.
The present invention is as follows.
1. A process for producing a polyacetal copolymer, wherein a polyacetal copolymer is continuously produced using at least 1 polymerization initiator (c) selected from the group consisting of a protonic acid and a Lewis acid and a molecular weight regulator (d), wherein trioxane is used as the main monomer (a), a cyclic methylal having at least one carbon-carbon bond is used as the comonomer (b),
the amount of the molecular weight regulator (d) to be supplied is periodically varied and supplied, and when the time of 1 cycle of the variation is P minutes and the average residence time in the polymerization reactor is T minutes, P/T is 0.3 to 3.
2. The method for producing a polyacetal copolymer according to claim 1, wherein the polymerization initiator (c) is at least one selected from the group consisting of a heteropoly acid and boron trifluoride or an ether complex thereof.
3. The method for producing a polyacetal copolymer according to 1 or 2, wherein the molecular weight modifier (d) is at least 1 selected from the group consisting of methylal, acetal and dibutoxymethane.
ADVANTAGEOUS EFFECTS OF INVENTION
According to the present invention, a polyacetal copolymer having excellent appearance after molding and small fluctuation in each product can be economically produced by periodically varying the amount of the molecular weight regulator without modifying the conventional polymerization equipment, adding the blending equipment, or the like.
Drawings
FIG. 1 is a schematic view of an example of a polymerization apparatus used in the production method of the present invention.
Detailed Description
The following describes specific embodiments of the present invention in detail, but the present invention is not limited to the following embodiments, and can be modified and implemented as appropriate within the scope of the object of the present invention.
Process for producing polyacetal copolymer
Trioxane (a)
The trioxane used as the main monomer in the present invention is usually a cyclic trimer of formaldehyde, which is obtained by reacting an aqueous formaldehyde solution in the presence of an acidic catalyst, and is purified by distillation or the like.
Cyclic methylal (b) having at least one carbon-carbon bond
Cyclic methylal having at least one carbon-carbon bond refers to a compound commonly used as a comonomer in the production of polyacetal copolymers. Specifically, 1, 3-dioxolane, 1,3, 6-trioxane, 1, 4-butanediol methylal, and the like are mentioned.
In the present invention, the cyclic methylal having at least one carbon-carbon bond is preferably used in an amount of 0.01 to 20 parts by mass, more preferably 0.05 to 5 parts by mass, based on 100 parts by mass of trioxane.
Polymerization initiator (c) >)
As the polymerization initiator, a polymerization initiator known in cationic copolymerization using trioxane as a main monomer can be used. Typically, a protic acid or a Lewis acid is used.
Proton acid
Examples of the protonic acid include heteropolyacids, isopolyacids, and perfluoroalkanesulfonic acids.
The heteropolyacid is a polyacid produced by heterogeneous condensation dehydration condensation, and has a single-or multi-core complex ion formed by condensing a specific heterogeneous element with a condensed acid group having a shared oxygen atom in the center. Isopoly acids are also referred to as isopoly acids, and refer to high molecular weight inorganic oxy acids formed from condensates of inorganic oxy acids of a single type of metal having a valence of V or VI.
Specific examples of the heteropoly acid include phosphomolybdic acid, phosphotungstic acid, phosphomolybdic vanadic acid, phosphotungstic vanadic acid, silicotungstic acid, silicomolybdic vanadic acid, and the like. From the viewpoint of polymerization activity, the heteropoly acid is particularly preferably selected from the group consisting of silicomolybdic acid, silicotungstic acid, phosphomolybdic acid, and phosphotungstic acid.
Specific examples of the isopoly acid include isopoly tungstic acid exemplified by paratungstic acid, metatungstic acid, and the like, isopoly molybdic acid exemplified by paramoly molybdic acid, metapoly vanadate, isopoly vanadate, and the like. Among them, homotungstic acid is preferable from the viewpoint of polymerization activity.
Specific examples of the perfluoroalkane sulfonic acid include trifluoromethane sulfonic acid, pentafluoroethane sulfonic acid, heptafluoropropanesulfonic acid, nonafluorobutane sulfonic acid, undecane sulfonic acid, tridecane sulfonic acid, pentadecafluoroheptsulfonic acid, heptadecafluorooctanesulfonic acid. Among these, trifluoromethanesulfonic acid is preferable from the viewpoint of polymerization activity.
Lewis acid
Examples of the Lewis acid include halides of boron, tin, titanium, phosphorus, arsenic and antimony, and specifically boron trifluoride, tin tetrachloride, titanium tetrachloride, phosphorus pentafluoride, phosphorus pentachloride, antimony pentafluoride and complexes or salts thereof.
Among these, boron trifluoride or an ether complex thereof is preferable from the viewpoint of polymerization activity. Examples of the ether complex of boron trifluoride include boron trifluoride diethyl etherate and boron trifluoride dibutyl etherate.
The amount of the polymerization initiator to be added is not particularly limited, but is preferably 0.1ppm or more and 50ppm or less, more preferably 0.1ppm or more and 30ppm or less, based on the total amount of all the monomers. Particularly preferably from 0.1ppm to 15 ppm.
Molecular weight regulator (d) >
In the production of the polyacetal copolymer of the present invention, a component for adjusting the molecular weight is used in addition to the above-mentioned components. As a component for adjusting the molecular weight, a chain transfer agent known in cationic polymerization can be used.
Specifically, methylal such as methylal, acetal, and dibutoxymethane, alcohols such as methanol, ethanol, and ethylene glycol, water, and the like. Among them, chain transfer agents which do not form unstable terminals, i.e., methylal, acetal, dibutoxymethane are preferable as the molecular weight regulator (d).
< polymerization of polyacetal copolymer >
In the polymerization of the polyacetal copolymer of the present invention, the amount of the molecular weight regulator (d) to be supplied is periodically varied. Specifically, the method is characterized in that P/T is 0.3 to 3 when P minutes is 1 cycle of the variation in the amount of the molecular weight regulator (d) to be supplied and T minutes is the average residence time in the polymerization reactor.
One unit of variation in the amount of the molecular weight regulator supplied was set as 1 cycle, and this was repeatedly supplied. The change from a large supply amount to a small supply amount (the opposite thereof) may be stepwise or continuous. The time containing the minimum repeating unit of the large and small amounts was taken as 1 period P minutes. The unit of time is minutes. The initial supply may be started from a small amount or a large amount, and there is no difference in the conventional state.
The average residence time T minutes in the polymerization reaction apparatus is the time taken for the mixture of the main monomer, the comonomer and the molecular weight regulator to be supplied to the apparatus together with the initiator and then discharged as the polyacetal copolymer from the other end of the reaction apparatus, and is determined by the following method.
After the polymerization reaction was started and the polymerization reaction was confirmed to be in a stable state based on the stabilization of the temperature and the discharge amount of each part of the reaction apparatus, the supply of the monomer, the molecular weight regulator and the initiator was stopped. Immediately the upper part of the polymerization reaction apparatus main body was opened to stop the polymerization, and the total mass Xg of the polyacetal copolymer present in the inside of the polymerization reaction apparatus was measured. The determination was made that X/y=t minutes when the feeding rate of the monomer to which the main monomer (a) and the comonomer (b) are added was set to Yg/min.
If P/T is less than 0.3, the surface appearance of a molded article made of the polyacetal copolymer becomes poor, and if P/T exceeds 3, the fluctuation in Melt Flow Rate (MFR) of molded pellets made of the polyacetal copolymer becomes large, and the quality of the surface appearance of the molded article becomes unstable.
The method for polymerizing the polyacetal copolymer of the present invention is not particularly limited, except that the amount of the molecular weight regulator (d) to be supplied is periodically varied. In the production, the polymerization reaction apparatus is not particularly limited, and a known apparatus can be used.
The polymerization initiator (c) of the present invention is preferably supplied in a constant amount continuously. The solvent may be diluted with an inert solvent which does not adversely affect the polymerization.
The deactivation of the polymerization initiator after the polymerization reaction can be carried out by a conventionally known method. For example, pellets can be produced by continuously adding an alkali compound to the product discharged from the polymerization machine after the polymerization reaction and melt-kneading the mixture.
Examples
Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples.
Examples 1 to 5 >
[ production of polyacetal copolymer ]
The polymerization apparatus used was of the continuous biaxial paddle screw extruder type. The outside of the main body is provided with a jacket for passing a medium for heating or cooling. The main body has a vertically divided structure, and has a structure in which the upper part is opened. 2 rotating shafts each having a large number of blades for stirring and pushing are provided in the longitudinal direction inside the polymerization reaction apparatus.
The temperature was adjusted by passing a medium at 80℃through the jacket, and a mixed solution containing 96.2 parts by mass of trioxane as the main monomer (a) and 3.8 parts by mass of 1, 3-dioxolane as the comonomer (b) was continuously supplied per unit time, and the supply amount of the molecular weight regulator (d) was periodically varied at the concentration shown in Table 1 (unit: mass ppm relative to the whole monomers). To which a polymerization initiator is supplied.
For example, in example 1, a polymerization initiator (c) was continuously added at a concentration (unit: mass ppm relative to the whole monomers) shown in Table 1 and copolymerization was performed. The boron trifluoride diethyl etherate as the polymerization initiator was a cyclohexane solution and the concentration was a value as boron trifluoride. In the case of phosphotungstic acid, a methyl formate solution is formed and added.
The polymerization reaction was confirmed to be in a stable state based on the stabilization of the temperature and the discharge amount of each part of the reaction apparatus. Thereafter, methylal was continuously supplied at 800ppm for 2 minutes, and then at 1200ppm for 2 minutes, which was taken as 1 cycle (4 minutes), and then the same supply pattern was repeated. Other embodiments are also possible.
To the polyacetal copolymer obtained, 0.1 mass% of melamine as the deactivator (e) and 0.3 mass% of triethylene glycol-bis [ 3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate ] as the antioxidant were added, and the mixture was melt-kneaded and extruded continuously using a twin-screw extruder equipped with a vent at a temperature of 220℃and a vacuum degree at the vent portion of 5mmHg to prepare pellets of the polyacetal copolymers of examples 1 to 5.
Thereafter, the supply of various raw materials, a polymerization initiator and a molecular weight regulator was stopped, the upper part of the polymerization reaction apparatus main body was immediately opened, and the polyacetal copolymer present in the interior was collected, and the total mass Xg thereof was measured. The average residence time of the polymerization reactor was defined as X/y=t, with the feed rate of the main monomer (a) and the comonomer (b) added being Yg/min.
Comparative examples 1 to 5
Pellets of polyacetal copolymers of comparative examples 1 and 2 were prepared in the same manner as in example except that the amount of the molecular weight modifier to be supplied was set to a constant value.
Pellets of polyacetal copolymers of comparative examples 3 to 5 were prepared by changing the supply fluctuation period of the molecular weight regulator and the average residence time of the polymerization reactor.
< evaluation >
Pellets of the polyacetal copolymers of the examples and comparative examples were dried at 135℃for 4 hours, and then subjected to Melt Flow Rate (MFR) and fluctuation thereof, and appearance evaluation of molded articles. The results are shown in tables 1 and 2. The evaluation was performed under an atmosphere of 50% RH at 23℃unless otherwise specified.
[ evaluation of MFR ]
Melt index measuring device: the MFR (g/10 min) was determined at a temperature of 190 ℃ under a load of 2.16kg in accordance with ISO 1133 using a Melt index model L202 (manufactured by takarathermitor). The measurement was performed 10 times in each example, and the MFR average value and standard deviation σ were obtained.
[ evaluation of appearance of molded article ]
Using injection molding machine day steel J75SS2A (Φ35), a flat plate of 50-angle 3t with a center 1-point pin gate of Φ1.5mm was injection molded under the following conditions. Then, the size of flow marks in the vicinity of the gate of the molded article was measured to visually evaluate the appearance. The level that can be used as a product is referred to as good, and the level that cannot be used is referred to as bad.
The molding conditions are as follows: barrel temperature: nozzle-C1-C2-C3
200-200-170-150℃
Mold temperature: 90 DEG C
Pressure maintaining: 750kg/cm 2
Injection time 4.5 seconds
Injection conditions: metering: 25-20-8mm
Speed of: 25-2.5 mm/s
TABLE 1
TABLE 2
From the evaluation results shown in tables 1 and 2, the molded article was excellent in appearance and uniformity of pellets within the scope of the present invention.
Description of the reference numerals
1. Polymerization reaction device
2. Feeding machine
3. Melt mixing extruder
4. Pellet material
(a) Trioxane
(b) Comonomers
(c) Polymerization initiator
(d) Molecular weight regulator
(e) Deactivator agent
AO antioxidant
Claims (3)
1. A process for producing a polyacetal copolymer, wherein a polyacetal copolymer is continuously produced using at least 1 polymerization initiator (c) selected from the group consisting of a protonic acid and a Lewis acid and a molecular weight regulator (d), wherein trioxane is used as the main monomer (a), a cyclic methylal having at least one carbon-carbon bond is used as the comonomer (b),
the amount of the molecular weight regulator (d) to be supplied is periodically varied and supplied, and when the time of 1 period of the variation is P minutes and the average residence time in the polymerization reactor is T minutes, P/T is 0.3 to 3,
the molecular weight regulator (d) is selected from linear methylal, alcohols and water.
2. The method for producing a polyacetal copolymer according to claim 1, wherein the polymerization initiator (c) is at least one selected from the group consisting of heteropoly acids and boron trifluoride or an ether complex thereof.
3. The method for producing a polyacetal copolymer according to claim 1 or 2, wherein the molecular weight modifier (d) is at least 1 selected from the group consisting of methylal, acetal and dibutoxymethane.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
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| JP2020-175927 | 2020-10-20 | ||
| JP2020175927A JP6992144B1 (en) | 2020-10-20 | 2020-10-20 | Method for producing polyacetal copolymer |
| PCT/JP2021/029863 WO2022085280A1 (en) | 2020-10-20 | 2021-08-16 | Method for producing polyacetal copolymer |
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| CN116209689A CN116209689A (en) | 2023-06-02 |
| CN116209689B true CN116209689B (en) | 2023-08-25 |
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Citations (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH10120746A (en) * | 1996-10-15 | 1998-05-12 | Polyplastics Co | Production of polyacetal resin |
| CN1209441A (en) * | 1997-08-22 | 1999-03-03 | 泛塑料株式会社 | Process for continuous production of polyacetal resin |
| JP2000169668A (en) * | 1998-12-02 | 2000-06-20 | Polyplastics Co | Polyacetal resin composition and molded product obtained therefrom |
| JP2007262107A (en) * | 2006-03-27 | 2007-10-11 | Asahi Kasei Chemicals Corp | Method for producing polyacetal copolymer |
| JP2007262108A (en) * | 2006-03-27 | 2007-10-11 | Asahi Kasei Chemicals Corp | Polyacetal copolymer |
| JP2010059356A (en) * | 2008-09-05 | 2010-03-18 | Mitsubishi Gas Chemical Co Inc | Branched-crosslinked polyacetal copolymer |
| JP2013213136A (en) * | 2012-04-02 | 2013-10-17 | Asahi Kasei Chemicals Corp | Method for producing polyacetal copolymer |
| CN104072710A (en) * | 2013-03-28 | 2014-10-01 | 旭化成化学株式会社 | Manufacturing method of polyacetal copolymer |
| CN104558460A (en) * | 2013-10-22 | 2015-04-29 | 旭化成化学株式会社 | Manufacturing method of polyacetal copolymer |
| CN104822721A (en) * | 2012-11-27 | 2015-08-05 | 宝理塑料株式会社 | Production method for polyacetal copolymer |
| JP2015193699A (en) * | 2014-03-31 | 2015-11-05 | ポリプラスチックス株式会社 | Method for manufacturing polyacetal copolymer |
| CN106905499A (en) * | 2015-10-28 | 2017-06-30 | 旭化成株式会社 | The manufacture method of Copolyacetal |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3208353B2 (en) * | 1997-06-27 | 2001-09-10 | ポリプラスチックス株式会社 | Method for producing polyacetal resin |
-
2020
- 2020-10-20 JP JP2020175927A patent/JP6992144B1/en active Active
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- 2021-08-16 WO PCT/JP2021/029863 patent/WO2022085280A1/en active Application Filing
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Patent Citations (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH10120746A (en) * | 1996-10-15 | 1998-05-12 | Polyplastics Co | Production of polyacetal resin |
| CN1209441A (en) * | 1997-08-22 | 1999-03-03 | 泛塑料株式会社 | Process for continuous production of polyacetal resin |
| JP2000169668A (en) * | 1998-12-02 | 2000-06-20 | Polyplastics Co | Polyacetal resin composition and molded product obtained therefrom |
| JP2007262107A (en) * | 2006-03-27 | 2007-10-11 | Asahi Kasei Chemicals Corp | Method for producing polyacetal copolymer |
| JP2007262108A (en) * | 2006-03-27 | 2007-10-11 | Asahi Kasei Chemicals Corp | Polyacetal copolymer |
| JP2010059356A (en) * | 2008-09-05 | 2010-03-18 | Mitsubishi Gas Chemical Co Inc | Branched-crosslinked polyacetal copolymer |
| JP2013213136A (en) * | 2012-04-02 | 2013-10-17 | Asahi Kasei Chemicals Corp | Method for producing polyacetal copolymer |
| CN104822721A (en) * | 2012-11-27 | 2015-08-05 | 宝理塑料株式会社 | Production method for polyacetal copolymer |
| CN104072710A (en) * | 2013-03-28 | 2014-10-01 | 旭化成化学株式会社 | Manufacturing method of polyacetal copolymer |
| CN104558460A (en) * | 2013-10-22 | 2015-04-29 | 旭化成化学株式会社 | Manufacturing method of polyacetal copolymer |
| JP2015193699A (en) * | 2014-03-31 | 2015-11-05 | ポリプラスチックス株式会社 | Method for manufacturing polyacetal copolymer |
| CN106905499A (en) * | 2015-10-28 | 2017-06-30 | 旭化成株式会社 | The manufacture method of Copolyacetal |
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| Publication number | Publication date |
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| WO2022085280A1 (en) | 2022-04-28 |
| JP2022067294A (en) | 2022-05-06 |
| CN116209689A (en) | 2023-06-02 |
| JP6992144B1 (en) | 2022-01-13 |
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