JP2960325B2 - Polyoxymethylene copolymer and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyoxymethylene copolymer in which a compound having a sterically hindered phenol group is chemically bonded as a copolymer component, and which itself has excellent heat stability and a method for producing the same.

[0002]

2. Description of the Related Art As is well known, polyoxymethylene is an engineering plastic having well-balanced and excellent properties in many physical properties such as excellent mechanical properties, electrical properties and chemical resistance. For example, it is widely used as a material for structural parts of automobile parts, electric / electronic equipment parts, mechanical parts, and the like. However, the polyoxymethylene polymer or the copolymer itself is an extremely unstable substance, and its molecular weight is degraded during various processing steps in production due to oxidative decomposition, thermal decomposition, etc., or during molding or use, and the like. As a result, the mechanical properties and the like are remarkably deteriorated, and the product cannot be put to practical use as it is because of the generation of decomposition products such as formaldehyde. Therefore, in general, after polymerization, the polymer is mixed with an antioxidant represented by a sterically hindered phenol compound and other various stabilizers to suppress the decomposition thereof, and is used for molding and subsequent use. Is common. However, as described above, the conventional general method of adding a stabilizer to the polymer once formed does not protect the polymer at all in the polymer production step until the stabilizer is added, decomposition in the treatment step, and the like. During the process, the decomposition reaction is performed simultaneously with the polymerization reaction, so that a sufficiently high degree of polymerization cannot be obtained, and a side reaction due to decomposition products adversely affects the polymerization reaction (degree of polymerization, polymerization yield, etc.).
In addition, the method of blending a stabilizer into the polymer once formed and melt-kneading has a limit in the dispersibility of the stabilizer, and the stabilizer may be unevenly distributed microscopically. Its stabilizing effect is still not sufficient. As a method for solving such a problem, the present applicant has developed a method of adding a sterically hindered phenol-based stabilizer to a monomer prior to polymerization or copolymerization and performing polymerization or copolymerization in the presence of the stabilizer. The decomposition reaction at the time is suppressed to obtain a polymer with a high degree of polymerization and a high yield, and it is also effective for the decomposition / suppression in a post-treatment step such as separation, purification, and removal of an unstable terminal of a residual monomer. Japanese Patent Application Laid-Open No. Sho 59-227916 (Japanese Patent Publication No. 3-63965) and Japanese Patent Application Laid-Open No. Sho 60-1216 (Japanese Patent Publication No. Sho 62
No. -13369), the sterically hindered phenol compound which coexists in such a method is still mixed as a separate substance from the polymer, and in particular, the polyoxymethylene polymer has a high crystallinity. It is easy to agglomerate due to crystallization at the time of solidification because of its solidification, and it is not uniform enough for microscopic processing and is still not enough for severe processing conditions. In addition, or during use, it is inevitable that part of the product will separate, exude, and scatter.For example, it will exude at the time of molding to contaminate the mold, and if the molded product is used at a particularly high temperature, it will exude to the surface and mold. There are problems such as deterioration of the appearance of the product,
Still further improvement was desired.

[0003]

Means for Solving the Problems In view of the above problems, the present inventors have made intensive studies to further improve the properties and found that a compound having a sterically hindered phenol group having an antioxidant (radical reaction suppression) function was obtained. By using a copolymer chemically introduced into polyoxymethylene as a copolymer component, it effectively acts as a stabilizer in suppressing the decomposition of the polymer being formed during the polymerization reaction, and the resulting polymer is sterically hindered. Since the phenol group is chemically bonded to the polymer chain, it is uniformly dispersed at the molecular level microscopically,
The present inventors have found that there is no inconvenience such as separation, agglomeration, leaching, and emission, and that a very small amount has a remarkable effect of inhibiting oxidation or radical decomposition, thereby leading to the present invention. That is, the present invention relates to (A) an oxymethylene group

[0004]

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(B) a copolymer unit having a sterically hindered phenol group represented by the following general formula (1): 0.001 to 1.0 mol% (based on oxymethylene group)

[0006]

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[However, at least one or both of R ₁ -and R ₂ -are an alkyl group having 1 to 8 carbon atoms, an alkoxy group, a phenyl-substituted alkyl group having 7 to 20 carbon atoms, and may be the same or different. May be. X is a divalent organic group linking the sterically hindered phenol group to the polymer main chain , and p is 0
３3, q is 0-3, and p + q ≦ 3 . (C) oxyalkylene group

[0008]

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[Where n is 2 to 4] 0 to 10 mol% (based on oxymethylene group) having a weight average molecular weight of 3,000 to 30
0,000 polyoxymethylene copolymer. Also, polyoxymethylene copolymer according the present invention, the (A ') of trioxane as a main monomer, (B') and sterically hindered phenol group represented by the following general formula (i), a cationic polymerizable functional group 0.003 to 3.0
Mol% (relative to trioxane) as a comonomer,
It can be produced by copolymerizing (C ') a cyclic ether or cyclic formal compound other than (B') with 0 to 30 mol% (relative to trioxane) as a comonomer in the presence of a cationic active catalyst.

[0010]

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[However, R _1- , R ₂ -and X are as defined above.
That] First, polyoxymethylene (hereinafter the present invention, POM
The structure of the copolymer will be described. The POM copolymer of the present invention has an oxymethylene group

[0012]

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Is a main repeating unit (A), and is formed by copolymerization with formaldehyde or ring-opening copolymerization using trioxane which is a cyclic trimer of formaldehyde as a raw material main monomer as described below. A feature of the POM copolymer of the present invention is that a copolymer component (B) having a sterically hindered phenol group represented by the following general formula (1) is chemically bonded to the main oxymethylene chain. .

[0014]

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In the formula (1), at least one of R ₁ -and R ₂ -is a sterically hindered group having at least one carbon atom, and specifically includes an alkyl group, an alkoxy group and a phenyl-substituted alkyl. And they may be the same or different. Preferably, R ₁ -and R ₂ -are alkyl groups having 3 or more carbon atoms, and a t-butyl group is most effective. Also, R ₁ -or
It is also preferable that at least one of R ₂ -is an alkyl group substituted with a phenyl group. Examples of R ₂ -include groups represented by the following formula (2).

[0016]

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[However, R ₃ -and R ₄ -are hydrogen or other substituents (eg, an alkyl group, an oxyalkyl group, a hydroxyl group, etc.), and R ₃ also has 1 or more carbon atoms, preferably 3 or more carbon atoms. Alkyl groups (eg, t-butyl groups) are preferred. The sterically hindered phenol group is bonded to a part of the main chain by a divalent organic group (-X-). The divalent organic group -X- is not particularly limited, but is generally an alkylene group, an oxyalkylene group, an (ether group), a thioether group,
It is a bonding group having an ester group or the like, or one or more thereof. Further, p and q constituting the main chain portion are such that p is 0 to 3,
q is 0 to 3 and p + q ≦ 3, and the copolymerized unit (B)
Is generally introduced at random positions in the POM copolymer and is uniformly distributed as shown in the polymerization method described later, and its content is 0.001 to 1.0 mol % (based on oxymethylene group).
And preferably 0.003 to 0.7 mol% (based on oxymethylene group). If the amount of such a copolymer unit (B) is too large, the polymerizability (degree of polymerization, yield, etc.) of the POM copolymer will be impaired, and the original properties of the POM such as crystallinity, melting point,
It is not preferable because it causes trouble in mechanical properties and the like. On the other hand, if the amount is too small, the intended effects such as thermal stability cannot be obtained, which is not preferable.

Next, the POM copolymer of the present invention is preferably a copolymer into which a copolymer component (C) other than (B) has been introduced. The copolymer component (C) is a copolymer component generally known as a POM copolymer, and generally has an ether bond having a carbon-carbon link,

[0019]

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(Where n = 2 to 4). Here, a part of hydrogen may be substituted with a substituent other than the formula (i) . The content of the copolymerized unit (C) is 10 mol%.
(Relative to oxymethylene unit) and is not necessarily an essential constituent unit, but is preferably present in an amount of 0.2 to 7.0 mol%, particularly 0.3 to 5.0 mol%, from the viewpoint of the stability of the copolymer and the reduction of unstable terminal portions. It is preferred that the content be contained in a mole%. Further, the POM copolymer of the present invention also includes a copolymer having a branched or crosslinked structure formed by a copolymer component having two ring-opening polymerizable functional groups as a part of the component (C). The terminal group of the POM copolymer of the present invention is not particularly limited and is optional. One, in immediately after polymerization but is intended to include relatively large amount of hemiacetal terminal (-O-CH ₂ -OH), removing the unstable hemiacetal terminal workup (e.g.

[0021]

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Any of the POM copolymers of the present invention, such as those having a terminal, n = 2-4) or those whose terminals have been stabilized by acetylation, etherification, etc., are included in the scope of the present invention.

The weight average molecular weight of the POM copolymer of the present invention is 3,000 to 300,000, preferably 5,000 to 200,000.
This can be adjusted to any value by adjusting the polymerization conditions described below, but has the advantage of obtaining a high molecular weight polymer which cannot be obtained by the conventional method.

Next, a method for producing the POM copolymer of the present invention will be described. POM copolymer of the present invention is trioxane or formaldehyde (A ') and a main monomer, (i) expression have sterically hindered phenol groups and comonomer compound having a cationically polymerizable functional groups (B' with) co It is produced by polymerization. As the main monomer, trioxane is typical and most suitable, and in this case, a known trioxane copolymerization method can be basically applied. The comonomer (B ') used for introducing the copolymerized unit (B) having a sterically hindered phenol group characterized by the present invention is the aforementioned
(i) Formula A compound having a sterically hindered phenol group and a polymerizable functional group, and examples of the polymerizable functional group include a cyclic ether group and a cyclic formal group. A typical example of the cyclic ether group is an epoxy group (glycidyl group), and a cyclic formal group is a cyclic group in which a part or all of the ring constituting part has an acetal bond, and includes a trioxane ring and a dioxolane. And cyclic functional groups such as a 1,3-dioxane ring, a trioxepane ring, a diethylene glycol formal ring, and a 1,4-butanediol formal ring. Among them, an epoxy group and a 1,3-dioxolane group are most preferred. For example, the following equation (3) or (4)
Compounds of the formula are mentioned as representative comonomers (B '). The part constituting the ring of the comonomer (B ') is a copolymerized copolymer.
In response, the ring will open to form part of the main chain.

[0025]

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[R _1- , R ₂ -and -X- are the same as above;
-X- for example

[0027]

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(However, n = 1 to 4, m = 1 to 3), -CH ₂
-CH ₂ -COOCH ₂ - it is a divalent organic group such as. These monomer compounds (B ') can be prepared by etherification or esterification by condensation reaction or the like using respective corresponding starting compounds having a functional group such as a hydroxyl group or a carboxylic acid group. By using such a comonomer having a specific cyclic group (B ′), the cyclic ether group or cyclic formal group thereof is subjected to ring-opening polymerization in the presence of a cationic catalyst in the same manner as trioxane to easily form a copolymerized unit in polyoxymethylene. Will be introduced. The content of copolymer component (B) is comonomer
The amount of comonomer (B ') used is adjusted to 0.003 to 3.0 mol%, preferably 0.01 to 2 mol, based on trioxane as the main monomer in order to obtain the above-mentioned preferable introduction amount. %. In the copolymerization reaction, the above comonomer (B ') is not always completely introduced into the polymer as a copolymer component, but there is no problem if a part of the comonomer (B') remains unreacted. Next, in the present invention, although not necessarily essential, a common comonomer (C ') other than (B') is further used in combination in the polymer.

[0029]

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It is preferable to introduce a copolymer component (where n = 2 to 4). Such a comonomer (C ′) has a carbon-carbon bond , that is, a carbon-carbon bond as a part of a ring component.
A cyclic ether or cyclic formal having , for example, ethylene oxide, 1,3-dioxolan, 1,3-
Examples include cyclic compounds such as dioxane, trioxepane, butylene glycol formal, and diethylene glycol formal, and derivatives thereof having a substituent other than the formula (1) may also be used.

The POM copolymer of the present invention can be used as a POM copolymer having a branched or crosslinked structure by using a compound having two or more reactive cyclic groups as described above. Examples of the comonomer used for such a purpose include alkylene glycol diglycidyl ether (alkylene group having 2 to 8 carbon atoms is preferable). Comonomer
The amount of (C ') to be used may be adjusted depending on the amount of the desired copolymerized unit (C) to be introduced, but is not more than 30 mol%, preferably 0.5 to 20 mol%, based on trioxane as the main monomer.

The POM copolymer of the present invention comprises the above monomer
It is produced by co-existing (A ′) and (B ′), and if necessary, (C ′), and copolymerizing using a cationically active catalyst.
The cation-active catalyst may be any known cation-active catalyst generally used for the polymerization of trioxane. For example, Lewis acids, especially boron, tin, titanium,
Phosphorus, halides such as arsenic and antimony such as boron trifluoride, tin tetrachloride, titanium tetrachloride, phosphorus pentachloride,
Compounds such as phosphorus pentafluoride, arsenic pentafluoride and antimony pentafluoride, and their complex compounds or salts, protonic acids such as trifluoromethanesulfonic acid, perchloric acid, esters of protic acids, especially perchloric acid and lower aliphatic acids Esters with alcohols (for example, tertiary butyl perchlorate), anhydrides of protic acids, especially mixed anhydrides of perchloric acid and lower aliphatic carboxylic acids (for example, acetyl perchlorate), or isopoly acids, heteropoly acids ( For example, phosphomolybdic acid), triethyloxonium hexafluorophosphate, triphenylmethylhexafluoroarsenate, acetylhexafluoroborate and the like can be mentioned. Among them, boron trifluoride or a coordination compound of boron trifluoride and an organic compound (for example, ethers) is the most common and suitable. The amount of the catalyst used in the present invention is preferably 1 × 10 ⁻⁴ to 2 × 10 ⁻² mol% based on all monomers. Further, impurities having a reaction stopping action,
For example, water, alcohols, acids (formic acid) or the like is, of course, that it is preferable substantially free, they all monomers, 1 × 10 ^-2 mol% or less.

The molecular weight of the copolymer of the present invention can be made higher than the conventional one by the presence of (B '), but can be adjusted by the amount of the chain transfer agent used at the time of polymerization. Typical examples of the chain transfer agent include a low molecular weight linear acetal compound such as methylal, but other known chain transfer agents in trioxane polymerization (molecular weight regulator).
May be used.

The copolymerization method of the present invention can be carried out with the same equipment and method as the conventionally known trioxane copolymerization method. That is, both batch type and continuous type are possible,
In addition, any of solution polymerization, melt bulk polymerization and the like may be used, but a continuous bulk polymerization method using a liquid monomer and obtaining a solid powder bulk polymer with the progress of polymerization is generally industrially preferable. In this case, an inert liquid medium can coexist as necessary. Continuous polymerization
A co-kneader, a twin-screw type continuous extrusion mixer, a twin-screw paddle type continuous mixer, and other conventional trioxane continuous polymerization devices can be used, and if it is a closed system, it is divided into two or more stages. Is also good. In particular, those having a crushing function such that a solid polymer produced by a polymerization reaction can be obtained in a fine form are preferable. After the polymerization is completed, the crude polymer discharged from the polymerization machine needs to be immediately mixed and contacted with a deactivator to deactivate the polymerization catalyst. In the present invention, as the basic compound for deactivating the polymerization catalyst, ammonia, or triethylamine,
Amines such as tributylamine and hindered amine, or hydroxides and salts of alkali metals and alkaline earth metals and other known catalyst deactivators are used. These deactivators are preferably dissolved in a cooling medium for the reaction product, such as water or an organic solvent such as cyclohexane, benzene, and toluene, and contacted with a catalyst simultaneously with cooling of the polymer to neutralize the same. It is particularly preferable to use an aqueous solution. At this time, if necessary, it is preferable to pulverize and treat as a fine powder.

In the present invention, the copolymer in which the polymerization catalyst has been deactivated is further subjected to washing, separation and recovery of unreacted monomers, drying and the like, if necessary, and further to a stabilization step if necessary. Additives such as various auxiliary stabilizers are added, melt-kneaded and pelletized to obtain a product. Examples of the co-stabilizer include nitrogen-containing compounds such as amidine compounds (melamine or derivatives thereof, cyanoguanidine, etc.) polyamides, oxides, hydroxides, inorganic or organic acid salts of alkali metals or alkaline earth metals (eg, carboxylic acid Salt), etc., or an acid or formaldehyde absorbent, and furthermore, a weather-resistant (light) stabilizer such as a triazole compound, a hindered amine compound (piperidine compound) or the like is used alone or in combination of two or more. If coexisting during the polymerization, the polymerizability is impaired. Therefore, it is necessary to add the compound after the formation of the polymer. Note that the antioxidant does not need to be added particularly after the polymer is generated from the gist of the present invention, but does not prevent addition if necessary.

The POM copolymer of the present invention is useful as such, but may be used in combination with other generally known polyoxymethylene polymers or copolymers, or may be used in addition to other general thermosetting polymers other than polyoxymethylene. It is also suitable as a composition obtained by melt-kneading with a plastic resin. Here, examples of other thermoplastic resins include, for example, polyolefin-based resins, polyester-based resins, polyamide-based resins, polystyrene-based resins, polyacryl-based resins, polyurethane-based resins, fluororesins, and the like. can do.
The polyoxymethylene copolymer of the present invention generally has excellent compatibility with other resins as described above as compared with general polyoxymethylene, and is suitable for forming a polymer alloy. Further, in order to impart desired properties to the POM copolymer or the composition thereof of the present invention, conventionally known additives, for example,
Additives such as lubricants, lubricants, nucleating agents, coloring agents such as dyes and pigments, release agents, antistatic agents, plasticizers, flame retardants and the like can be added. In addition, powdery or plate-like fillers such as glass fibers, carbon fibers, other inorganic or organic fibrous reinforcing materials, glass beads, glass flakes, and mica can also be appropriately compounded.

[0037]

According to the POM copolymer of the present invention, a sterically hindered phenol group having a stabilizing function is chemically bonded directly to a polymer chain and is uniformly distributed at a molecular level. Compared to the case where a phenol compound is blended as a stabilizer, it exhibits a sufficient stabilizing function with a small amount,
Even if harsh conditions are adopted in the post-treatment process, molding, and use, there is no inconvenience such as separation, agglomeration, leaching, and diffusion.For example, the stabilizer is separated and adheres to the mold during molding. In addition, even if the mold is contaminated or the molded product is used at a high temperature, the conventional problems such as leaching and deterioration of the surface condition of the molded product can be largely improved. It has an excellent effect on decomposition and degradation, and is extremely excellent in maintaining initial physical properties. Further, according to the production method of the present invention, a decrease in the degree of polymerization is suppressed in the subsequent treatment steps including the polymerization step, so that a polymer having an unprecedented high degree of polymerization can be obtained and maintained.

[0038]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but it is needless to say that the present invention is not limited to these examples. Examples 1 to 7 and Comparative Examples 1 to 4 A sealed autoclave having a jacket through which a heating medium can pass and a stirring blade was kept at 80 ° C., and trioxane and a comonomer as shown in Table 1 were used as a comonomer.
(B ') and (C') were added and mixed well, and the temperature was adjusted to 80 ° C. Then, a cyclohexane solution of boron trifluoride butyl etherate (30 ppm as boron trifluoride per trioxane) was added as a catalyst. To initiate polymerization. Then, after 5 minutes, triethylamine was added to the autoclave.
Water containing 1% was added to deactivate the catalyst to stop the polymerization reaction, and at the same time, the contents were taken out, pulverized, washed with hot water and then with acetone, and dried at 80 ° C. with hot air. The properties of this polymer were examined as described below. Also, for comparison, the case where the sterically hindered phenol compound (B ′) was not added as a comonomer, and the case where a sterically hindered phenol (b ′) having no polymerizable functional group was added instead of (B ′). A polymerization reaction was carried out in the same manner, and a post-treatment was carried out in the same manner, and polymer characteristics were examined. The results are shown in Table 1. The comonomer and the like used for the polymerization are the following substances.

[0039]

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[0040] The measurement of the structural characteristic value and the like of the obtained polymer is as follows. -Polymerization yield: The weight of the polymer obtained based on the total amount of monomers supplied. Confirmation of copolymerized units (B) and (C): The obtained polymer was added to dimethyl sulfoxide containing 1% of tributylamine, dissolved at 150 ° C., poured into a large amount of acetone and reprecipitated. . The obtained fine powdery polymer was collected by filtration with a glass filter, washed with acetone, blow-dried at 40 ° C., and subsequently vacuum-dried at 80 ° C. to isolate and purify the copolymer. A predetermined amount of this copolymer powder was added to methanol-concentrated hydrochloric acid (4: 1) and decomposed by heating to remove a fraction below 60 ° C. (oxymethylene units were decomposed into formaldehyde and converted to methylal to form a system. Removed outside). Then, a predetermined amount of a standard substance was added to the residue neutralized with sodium methylate and dried under reduced pressure, dissolved in deuterated acetone, and the contents of (B) and (C) were calculated by NMR. The amounts of the sterically hindered phenol groups (B) and ethylene oxide groups (C) introduced and bound by copolymerization were determined. Weight-average molecular weight (Mw): Weight-average molecular weight determined by GPC-LALLS method using hexafluoroisopropyl alcohol as the mobile phase for the purified polymer. -Alkali decomposition rate: 1% of the copolymer is 50% containing 0.5% ammonium hydroxide
Place in 100 ml of aqueous methanol solution at 180 ° C, 45
After heating for 1 minute, the amount of formaldehyde decomposed and eluted in the liquid is quantitatively analyzed and is shown in terms of% by weight based on the polymer. -Thermal decomposition weight loss rate: The weight loss rate when the copolymer was heated at 220 ° C for 90 minutes was determined by a thermobalance.

[0041]

[Table 1]

Example 8, Comparative Examples 5 to 6 A continuous polymerization reactor having a cross section in which two circles partially overlap, a jacketed barrel through which a heat (cooling) medium is passed on the outside, and a barrel meshing with the inside. 2 with many paddles
Using a continuous mixing propulsion reactor consisting of two rotating shafts, passing hot water of 80 ° C. through the jacket thereof, rotating the two rotating shafts at a constant speed, and adding 0.1 mol% (based on trioxane) to one end of the two rotating shafts. Comonomer (B'-1) and 4 mol% (based on trioxane) of comonomer (C'-1) and methylal 0.04 mol%
The dissolved trioxane is continuously supplied, and at the same time, a cyclohexane solution of boron trifluoride dibutyl etherate is continuously added at the same rate at a rate of 25 ppm as boron trifluoride to the total amount of monomers. The polymerization was carried out, and the reaction mixture discharged from the other end was immediately poured into water containing 0.1% of triethylamine and pulverized, and left overnight at room temperature to deactivate the catalyst. The obtained polymer flakes were collected by centrifugation, washed with warm water at 70 ° C., and dried at 50 ° C. for 2 days (Example 8). On the other hand, for comparison, when the same treatment was carried out without adding (B'-1) to the monomer (Comparative Example 5), and steric hindrance having no polymerizable functional group instead of (B'-1) When the phenol compound (b'-1) was added (Comparative Example 6), copolymerization and post-treatment were similarly performed to obtain a copolymer. The results of examining the characteristic values of these copolymers in the same manner as described above are shown in Table 2.

[0043]

[Table 2]

Next, 0.15% of polyamide (nylon 12) as an auxiliary stabilizer was added to the resulting copolymer, and the mixture was mixed well. The mixture was melt-kneaded while being deaerated using a twin-screw extruder equipped with a vent. Then, unstable portions were decomposed and removed to prepare pellets.

Incidentally, the amount of the sterically hindered phenol corresponding to that of Example 8 was used for the polymer of Comparative Example 5 at the time of melt extrusion.
Pellets containing (B'-1) were also prepared (Comparative Example 5 ').
Next, a test piece was formed and formed from these pellets by an injection molding machine under a predetermined condition, and the leached state of the sterically hindered phenol was compared based on the cloudiness of the mold surface at that time.
The molded test piece was left in an oven at 130 ° C. for 50 days to examine the surface condition of the molded product and compare the state of leaching.
Further, the strength and elongation of the test piece were measured, and its decrease (deterioration) was examined. Table 3 shows the results.

[0046]

[Table 3]

* Note: Comparative Example 5 was blended with sterically hindered phenol (B'-1) to form a melt-extruded pellet.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kuniyuki Sugiyama 973 Miyajima Polyplastics Co., Ltd., Fuji City, Shizuoka Prefecture (58) Field surveyed (Int.Cl. ⁶ , DB name) C08G 2/00-2 / 38

Claims (12)

(57) [Claims] (1) an oxymethylene group (A) And (B) a copolymer unit having a sterically hindered phenol group represented by the following general formula (1): 0.001 to 1.0 mol% (based on oxymethylene group) (However, at least one or both of R ₁ -and R ₂ -are an alkyl group having 1 to 8 carbon atoms, an alkoxy group, a phenyl-substituted alkyl group having 7 to 20 carbon atoms, and may be the same or different. Good. X is a divalent organic group linking the sterically hindered phenol group to the polymer main chain , p is 0 to 3, and q is 0
３3, p + q ≦ 3 . (C) oxyalkylene group [Where n is 2 to 4] A polyoxymethylene copolymer having a weight average molecular weight of 3,000 to 300,000, comprising 0 to 10 mol% (based on oxymethylene group). 2. The polyoxymethylene copolymer according to claim ₁ , wherein R ₁ − and R ₂ − in the sterically hindered phenol group constituting the general formula (1) are t-butyl groups. 3. The organic compound according to claim 1, wherein the divalent organic group -X- constituting the general formula (1) is at least one organic group selected from an alkylene group, an oxyalkylene group (ether group), a thioether group and a carboxylate group. 3. The polyoxymethylene copolymer according to claim 1, comprising a divalent group containing these organic groups. (4) An oxyalkylene copolymer unit of (C) is added in an amount of 0.2
A polyoxymethylene copolymer containing ７7 mol% (based on oxymethylene group). Wherein (A ') of trioxane as a main monomer, (B') and sterically hindered phenol group represented by the following general formula (i), the compound 0.003 having a cationic polymerizable functional group to 3.0
The presence of a cation-active catalyst, in which 0% to 30% by mole (based on trioxane) is a copolymerized monomer, and 0 to 30% by mole (based on trioxane) is a cyclic ether or cyclic formal compound other than (B ′) as (C ′). A method for producing a polyoxymethylene copolymer having a sterically hindered phenol group, which is copolymerized under the following conditions. Embedded image [However, R _1- , R ₂ -and X are as described above] 6. The method for producing a polyoxymethylene copolymer according to claim 5, wherein the cationically polymerizable functional group constituting the copolymerizable monomer (B ′) is a cyclic ether group and / or a cyclic formal group. 7. The method for producing a polyoxymethylene copolymer according to claim 6, wherein the cyclic ether group constituting the comonomer of (B ′) is an epoxy group or a group containing the same. 8. The process for producing a polyoxymethylene copolymer according to claim 6, wherein the cyclic formal group constituting the copolymer monomer of (B ′) is a group having a dioxolane ring or a 1,3-dioxane ring. 9. A compound of the formula (B ')
R ₁ -and R _{2 in the} sterically hindered phenol group represented by (i)
The method for producing a polyoxymethylene copolymer according to any one of claims 5 to 8, wherein-is a t-butyl group. 10. A general formula constituting the copolymerized monomer of (B ′)
(i) the divalent organic group -X- is at least one organic group selected from an alkylene group, an oxyalkylene group (ether group), a thioether group and a carboxylate group, or a divalent group containing these organic groups; The method for producing a polyoxymethylene copolymer according to any one of claims 5 to 9, comprising a group represented by the following formula: 11. The cyclic ether or cyclic formal of the comonomer (C ′) is at least one selected from ethylene oxide, 1,3-dioxolan, 1,3-dioxane, 1,4-butanediol formal, and diethylene glycol formal. The method for producing a polyoxymethylene copolymer according to any one of claims 5 to 10, wherein 12. The amount of the comonomer (C ') added is 0.5 to 20.
The method for producing a polyoxymethylene copolymer according to any one of claims 5 to 11, which is mol% (relative to trioxane).