JPH0598028A - Polyoxymethylene extrudate - Google Patents

Abstract

PURPOSE:To obtain a polyoxymethylene extrudate improved in mechanical properties and high-temperature durability by introducing specified oxyalkylene units into a polymer comprising repeating polyoxymethylene units. CONSTITUTION:Formaldehyde or trioxane and a cyclic ether of formula I (wherein R0 and R0 are each H, alkyl or phenyl; and m is 2-6) or a cyclic formal of formula II are reacted with each other at 60-200 deg.C for 10sec to 100min in the presence of a cationic polymerization catalyst. The catalyst is deactivated by contact with a basic neutralizing agent to obtain a polymer terminated with alkoxy, hydroxyalkoxy or formate groups and having a structure derived by introducing 0.1-5.0mol, per 100mol of the oxymethylene units, oxyalkylene units of formula II into a polymer comprising repeating oxymethylene units. This polymer is extruded at its melting point to 270 deg.C.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a polyoxymethylene extrusion molded article. More specifically, it is an extrusion molded article composed of a polyoxymethylene copolymer having a specified main chain composition and terminal group composition, and has excellent mechanical properties and is also excellent in durability in an atmosphere exposed to a high temperature for a long period of time. It relates to molded articles.

[0002]

2. Description of the Related Art Polyoxymethylene is widely used as an engineering plastic having well-balanced mechanical properties in electric, electronic parts, automobile parts and the like. Conventionally, polyoxymethylene includes a homopolymer obtained by homopolymerizing formaldehyde or trioxane and a copolymer obtained by copolymerizing formaldehyde or trioxane with a cyclic ether.

The extrusion-molded product obtained from the homopolymer has excellent mechanical properties, but when used in an atmosphere exposed to a high temperature for a long time, it could not be used due to the decomposition of the polymer itself. This is because homopolymer is a homopolymer,
This is because no oxyalkylene unit that stops decomposition is inserted in the main chain and the end is stabilized with an acetate group. On the other hand, the extrusion-molded product of the copolymer has excellent durability in an atmosphere exposed to high temperature for a long time, but its mechanical properties are inferior to those of the homopolymer, and a satisfactory extrusion-molded product has not been obtained. ..

[0004]

DISCLOSURE OF THE INVENTION The present invention provides a polyoxymethylene extrusion having excellent mechanical properties that cannot be achieved by conventional polyoxymethylene extrusion moldings and excellent durability in an atmosphere exposed to a high temperature for a long time. It relates to molded articles.

[0005]

The polyoxymethylene used as a raw material for the polyoxymethylene extruded product of the present invention is
It has the specified main chain composition and end group composition. When this specific polyoxymethylene is used, an extruded product having excellent mechanical properties and durability in an atmosphere exposed to a high temperature for a long time can be obtained.

That is, according to the present invention, an oxyalkylene unit represented by the following general formula is contained in a polymer composed of repeating oxymethylene units (--CH ₂ O--).

[0007]

[Chemical 2] (Ro, R'o: may be the same or different, hydrogen,
It is selected from an alkyl group and a phenyl group. n is an integer of 1 or more, and m = 2 to 6) is 100 mol of an oxymethylene unit.
The present invention relates to a polyoxymethylene extrusion-molded product having a structure in which 0.1 to 0.5 mol is inserted and the polymer end group is an alkoxy group, a hydroxyalkoxy group, or a formate group.

Next, the present invention will be specifically described. In the present invention, the first important point is the insertion rate of oxyalkylene units. That is, the insertion ratio of oxyalkylene units in the polymer was 0. 0 per 100 mol of oxymethylene units.
Only when the amount is in the range of 1 to 0.5 mol, an extruded product having excellent mechanical properties and excellent durability in an atmosphere exposed to high temperature for a long time can be obtained. When the insertion rate of oxyalkylene units is less than 0.1 mol, durability in an atmosphere exposed to high temperature for a long time is poor. On the other hand, if the insertion rate of oxyalkylene units exceeds 0.5 mol, mechanical properties are deteriorated and a satisfactory extruded product cannot be obtained.

The insertion rate of oxyalkylene groups in the polymer is confirmed by the following method. Polymer 1 / 10N, HCl
When hydrolyzed in an aqueous solution at 120 ° C. for 2 hours, the oxymethylene unit becomes formaldehyde and the oxyalkylene unit becomes

[0010]

[Chemical 3] (Ro and R'o may be the same or different, and hydrogen,
It is selected from an alkyl group and a phenyl group. n is an integer of 1 or more. It becomes an alkylene glycol represented by m = 2 to 6). It can be confirmed by analyzing and quantifying alkylene glycol using gas chromatography and liquid chromatography.

The sequence of oxyalkylene units in the polymer is also an important requirement. The oxyalkylene unit is
It is preferable to disperse in the polymer by itself as much as possible without forming blocks. That is, n representing the sequence of oxyalkylene units is preferably such that the ratio of n = 1 is 95 mol% or more of the whole oxyalkylene units and the ratio of n ≧ 2 is 5 mol% or less of the whole oxyalkylene units. If the ratio of n = 1 is less than 95 mol%, the durability in an atmosphere exposed to a high temperature for a long time is not sufficient.

The sequence of oxyalkylene groups in the polymer is confirmed by the following method. 1 / 10N polymer,
When hydrolyzed in an aqueous HCl solution at 120 ° C. for 2 hours,
The oxymethylene unit becomes formaldehyde, and the oxyalkylene unit becomes the alkylene glycol represented by the formula (I). It can be confirmed by analyzing and quantifying alkylene glycol using gas chromatography and liquid chromatography.

Next, the carbon number m of the oxyalkylene unit is
It must be in the range of 2-6. When m is 1, the obtained polymer is a polyoxymethylene homopolymer, and its extrusion-molded product has poor durability in an atmosphere exposed to a high temperature for a long time. On the other hand, when m is 7 or more, the extrusion molded product has low mechanical properties. The terminal group structure and terminal group composition of polyoxymethylene, which is a raw material for the extrusion-molded article of the present invention, are important points for obtaining a good extrusion-molded article. The terminal group of polyoxymethylene is an alkoxy group or a hydroxyalkoxy group represented by the following formula.

[0014]

[Chemical 4] (Ro and R'o may be the same or different, and hydrogen,
It is selected from an alkyl group and a phenyl group. m = 2-6),
Only formate groups (-OCHO) are allowed. In the case of a terminal group other than these groups, for example, a hydroxyl group (—OH), an acetate group (—OCOCH ₃ ), etc., the durability in an atmosphere exposed to a high temperature for a long time is inferior, so that the extrusion molded article of the present invention It is not suitable as a terminal group of polyoxymethylene as a raw material.

Next, a method for producing polyoxymethylene, which is a raw material of the present invention, will be described. Polyoxymethylene, which is a raw material for the extrusion-molded article of the present invention, is a compound of the general formula

[0016]

[Chemical 5] (Ro and R'o may be the same or different and are selected from hydrogen, an alkyl group and a phenyl group. M = 2
A cyclic ether represented by 6) or a general formula

[0017]

[Chemical 6] (Ro and R'o may be the same or different and are selected from hydrogen, an alkyl group and a phenyl group. M = 2
It can be obtained by copolymerizing with the cyclic formal represented by 6). This polyoxymethylene can also be obtained by reacting a polyacetal homopolymer with the above cyclic ether or cyclic formal in the presence of a cation catalyst.

The cyclic ether used for synthesizing the polyoxymethylene includes, for example, ethylene oxide, propylene oxide, butylene oxide, styrene oxide and the like. Examples of the cyclic formal include ethylene glycol formal, diethylene glycol formal, 1,3-propanediol formal, 1,4-butanediol formal, and 1,5.
-Pentanediol formal, 1,6-hexanediol formal and the like can be mentioned. It is important to improve the dispersion of oxyalkylene units during polymerization. Good dispersion can be achieved by the following method.

Formaldehyde or trioxane and cyclic ether or cyclic formal are thoroughly mixed in the presence of a cationic catalyst at a temperature of 100 ° C. or lower to form a cyclic intermediate in advance. The higher the ratio of cyclic ether or cyclic formal incorporated into the cyclic intermediate to the cyclic ether or cyclic formal present alone, the better the dispersion of oxyalkylene units. In that sense, when the ratio of the cyclic ether and the cyclic formal which are present alone is 5 mol% or less, the dispersion of the oxyalkylene group becomes good.

By copolymerizing the previously formed cyclic intermediate with formaldehyde or trioxane, a polyoxymethylene copolymer having good stability can be obtained. As the polymerization catalyst, a cationic active catalyst such as Lewis acid, protic acid and its ester or anhydride is used. Examples of the Lewis acid include boron, tin, titanium, phosphorus, arsenic and antimony halides, and specific examples include boron trifluoride, tin tetrachloride, titanium tetrachloride, phosphorus pentafluoride, phosphorus pentachloride, Examples include arsenic pentafluoride, antimony pentafluoride, and complex compounds or salts thereof. Further, specific examples of the protonic acid, its ester or anhydride include perchloric acid, trifluoromethanesulfonic acid, perchloric acid-tertiary butyl ester, acetyl perchlorate, trimethyloxonium hexafluorophosphate and the like.

The polymerization apparatus used for the polymerization is a batch type,
Any of continuous type may be used, and as a batch type polymerization apparatus,
A reaction vessel with a stirrer used in the general formula can be used.
As the continuous polymerization device, a self-cleaning mixer such as a cokneader, a twin screw type continuous extrusion kneader, or a twin screw paddle type continuous mixer can be used. The polymerization temperature is 60 to 200 ° C., preferably 80 to 170 ° C. The polymerization time is not particularly limited, but is generally 1
0 second or more and 100 minutes or less are selected.

The polymer thus obtained undergoes depolymerization by the catalyst contained in the polymer, so it is necessary to deactivate the catalyst. Examples of the deactivating method include a method of deactivating in an aqueous solution containing a basic neutralizing agent or in an organic solvent. Examples of the basic neutralizing agent include triethylamine, tributylamine, calcium hydroxide and the like, and examples of the organic solvent include saturated aliphatic hydrocarbons such as n-hexane,
Examples thereof include aromatic hydrocarbons such as benzene and toluene.

The deactivation temperature is 20 to 90 ° C., preferably 30.
~ 60 ° C. The deactivation time is 5 minutes to 200 minutes.
It is also possible to grind the polymer in order to deactivate the catalyst more completely. After the polymerization catalyst is deactivated, the deactivating liquid containing the polymer is filtered, washed, and dried. In addition, as another deactivating method, a. Alkali metal oxides, alkaline earth metal oxides, 3
An ion adsorbent containing, as a main component, at least two kinds of oxides selected from valent and tetravalent element oxides; or b. General formula M1 _1-x M2 _x (OH) _{2 An} ^- _{x / n} · mH ₂ O (wherein M1 represents at least one divalent metal selected from alkaline earth metals, and M2 is trivalent) Showing metal,
A ^n- represents an n-valent anion. Further, x is O <x ≦ 0.5.
And m is a positive number. 0.001 to 5.0 wt% of at least one selected from the ion adsorbents represented by
% And melt-mixed.

Here, Na is used as the alkali metal oxide.
₂ O, K ₂ O and the like, alkaline earth metal oxides such as MgO and CaO, and oxides of trivalent and tetravalent elements such as Al ₂ O ₃ , SiO ₂ and TiO ₂ .
₂ etc. As the ion adsorbent containing at least two kinds of oxides selected from these oxides as main components, specifically, 2.5MgO.Al ₂ O ₃ .nH ₂ O and 2Mg
O · 6SiO ₂ · n H ₂ O, Al ₂ O ₃ · 9SiO ₂ · n
H ₂ O, Al ₂ O ₃ , Na ₂ O, 2CO ₃ , nH ₂ O,
Examples include Mg _0.7 Al _0.3 O _1.15 . In the general formula M1 _1-x M2 _x (OH) _{2 An} ^- _{x / n} · mH ₂ O, examples of M1 are Mg, Ca, etc., examples of M2 are B, Al, Ga, In, Ti, Tl etc., a CO ₃ ^2- examples of ^{_{n-, OH -, HCO 3 -}} , H 2 PO 4 -, NO
₃ ^-, I ^-, salicylic acid ion ^-, citrate ions ^-,
Tartrate ion- ^{and the} like. Particularly preferable examples include CO ₃ ²⁻ and OH ⁻ . Specific examples of this type of ion adsorbent include Mg _0.75 Al _0.25 (OH) ₂ CO
₃ Natural hydrotalcite represented by _0.125 · 0.5H ₂ O, Mg _4.5 Al ₂ (OH) ₁₃ CO ₃ · 3.5H ₂ O
There is a synthetic hydrotalcite represented by the above. The deactivator can be added to the polymerization machine after the completion of the polymerization, or in a continuous polymerization machine, by supplying it to the latter stage of the polymerization machine or by adding and mixing it to the polymer discharged from the polymerization machine. The polymer to which the deactivator is added can be further completely melted and mixed to deactivate the polymerization catalyst. Melt mixing is performed in the temperature range from the melting point of the polymer to 270 ° C. Examples of the melt mixing device include a single screw type continuous extruder, a co-kneader, and a twin screw type continuous extruder.

When the polymer obtained by the above-mentioned deactivation method has an unstable terminal hydroxyl group, it is subjected to heat treatment with a basic substance such as an aqueous solution of triethylamine by a conventionally known method to form an unstable portion. To remove.
By the above method, polyoxymethylene, which is a raw material for the extrusion molded product, can be obtained. Furthermore, if necessary, conventionally known additives such as an antioxidant, a heat stabilizer, a pigment, a nucleating agent, an antistatic agent, a lubricant, an ultraviolet absorber and the like are kneaded, and used as a raw material for an extrusion molded product. Obtain oxymethylene.

Examples of the extrusion molded article in the present invention include extrusion molded articles such as round bars and sheets. Examples of the extrusion molding device include an extrusion device in which an extrusion die device is connected to a conventionally used screw extruder. The extrusion temperature is from the melting point to 270 ° C, preferably 180 to 230
℃. Extruded products such as round bars and sheets obtained by extrusion are cut into a desired size and shape.

The extrusion-molded article of the present invention has excellent mechanical properties and can be widely used for various purposes as a molded article having excellent durability in an atmosphere exposed to a high temperature for a long time.

[0028]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to the examples. The measurement items in the examples are as follows. 1. Oxyalkylene unit insertion rate and sequence 10 g of the copolymer is placed in 100 ml of 3N HCl aqueous solution and heated in a sealed container at 120 ° C. for 2 hours for decomposition. After cooling, the amounts of alkylene glycol, dialkylene glycol and trialkylene glycol in the aqueous solution are measured by gas chromatography (FID), and the amount of oxyalkylene units is expressed by mol% based on the oxymethylene units of the copolymer. 2. Terminal formate group The carbonyl group of the formate group at 1710 cm ^-1 is analyzed and quantified by infrared absorption spectroscopy. The ratio (β) of formate groups per 100 mol of oxymethylene groups is calculated using the following formula.

[0029]

[Equation 1] 3. Terminal hydroxyalkoxy group Acrylate the polymer with acetic anhydride,

[0030]

[Chemical 7] (Ro and R'o may be the same or different, and hydrogen,
It is selected from an alkyl group and a phenyl group. m = 2 to 6). Then, using the infrared absorption spectrum,
Absorbance of carbonyl group of acetyl group at 55 cm ^-1 and 14
The absorbance of the oxymethyl group at 70 cm ^-1 is measured. The ratio (α) of hydroxyalkoxy groups per 100 mol of oxymethylene groups is calculated using the following formula.

[0031]

[Equation 2] 4. Methoxy group Quantification using the modified Zeisel method, oxymethylene group 10
The ratio of methoxy groups per 0 mol is represented by γ (mol). 5. According to MI ASTM D-1238-86. 6. Tensile Strength An extrusion molded product is cut into a shape according to ASTM D-638 and measured according to ASTM D-638. 7. Durability at high temperature The extruded product was cut into a shape according to ASTM D-638, and this test piece was left in a gear oven at 120 ° C for 60 days. The tensile strength of the taken-out test piece is measured according to ASTM D-638, and the retention rate for the tensile strength immediately after cutting is determined.

[0032]

Example 1 High-purity trioxane (water in orioxane ≦ 5 PPM, formic acid 10 PPM) 3000 gr, ethylene oxide 13.0 gr, methylal 0.50 gr as a molecular weight regulator were placed in a kneader having two Σ blades, and 70 ° C. The temperature was raised to. Next, 0.10 gr of boron trifluoride dibutyl etherate was added to start the reaction. After 3 minutes, the contents of the kneader were sampled and analyzed by gas chromatography and liquid chromatography. As a result, ethylene oxide was changed to the following cyclic compounds. (Calculated from concentration analysis value) 1,3-dioxolane 0.135 mol 1,3,5-trioxepane 0.106 mol 1,3,5,7-tetraoxacyclononane 0.054 mol At this stage, the content liquid of the kneader Was transparent and no polymer formation was observed.

After 230 seconds had passed from the start of the reaction, 0.15 gr of boron trifluoride dibutyl etherate was further added to continue the reaction. Simultaneously with the additional addition of boron trifluoride dibutyl etherate, the contents of the kneader became cloudy, indicating the formation of a polymer. Further, after 30 minutes, 100 parts by weight of water containing 5% of triethylamine was added to the monomer, and the mixture was stirred for 1 hour. After deactivating the catalyst, the content was taken out and finely pulverized. The finely ground polymer was filtered, washed with acetone and dried.

Further, with respect to 100 parts by weight of the obtained polymer, 5 parts by weight of water, 1 part by weight of triethylamine, 2,
0.2 parts by weight of 2'-methylenebis (4-methyl-6-t-butylphenol) was added, and the mixture was melt-stabilized at 200 ° C and 50 torr using an ordinary vented single-screw extruder, and then an oxyalkylene unit was inserted. The amount and the terminal composition were measured. Furthermore, a 30 mmφ round bar molded product was obtained using an extrusion molding apparatus. The obtained round bar is ASTM D-638.
The test piece according to the above was cut, and the tensile strength was measured. Furthermore, after the test piece was left in a gear oven at 120 ° C. for 60 days, the tensile strength was measured and the retention rate of the tensile strength was obtained. The results are shown in Table 1.

[0035]

Examples 2 to 3 Except that the amount of ethylene oxide added was changed to that shown in Table 1, the method of synthesizing polyoxymethylene, which is a raw material for extruded products, the method of measurement and the method of measuring extruded products were all the same as Example 1. The same operation was performed. The results are shown in Table 1.
Shown in.

[0036]

Examples 4 to 5 The same operation as in Example 1 was performed except that ethylene oxide was changed to 1,3-dioxolane and the addition amount was changed to that shown in Table 1. The results are shown in Table 1.

[0037]

Comparative Example 1 Just as in Example 1, a kneader having two Σ blades was charged with high-purity trioxane, ethylene oxide, and methylal, and the temperature was raised to 70 ° C. Then, 0.25 gr of boron trifluoride dibutyl etherate was added to start the reaction. Simultaneously with the addition of the boron trifluoride dibutyl etherate, the contents of the kneader became cloudy, indicating the formation of a polymer. Triethylamine 5 after 30 minutes
% Of water was added to the monomer and the mixture was stirred for 1 hour to deactivate the catalyst, and then the content was taken out. The finely pulverized polymer was filtered, washed with acetone and dried to obtain a polymer.

Further, the completely same operation as in Example 1 was carried out to measure the oxyethylene insertion rate, sequence and terminal group.
Further, the same operation as in Example 1 was carried out to obtain a round bar extruded product, and then the evaluation was performed.

[0039]

[Comparative Examples 2 to 4] Except that the amount of ethylene oxide added was changed to that shown in Table 1, the method for synthesizing polyoxymethylene as a raw material for the extruded product, the measuring method, and the measuring method for the extruded product were all in Comparative Example 1. The same operation was performed. The results are shown in Table 1.
Shown in.

[0040]

Comparative Example 5 The same operation as in Example 1 was carried out to polymerize the polyoxymethylene as a raw material for the extrusion molded product and deactivate the catalyst contained in the polymer. The obtained polymer was acetylated with acetic anhydride, and the insertion rate terminal composition of the oxyalkylene unit was measured in the same manner as in Example 1. Further, extrusion molding was performed, and the same evaluation as in Example 1 was performed.

In addition, the infrared absorption spectrum was used for the measurement of the terminal acetyl group in the same manner as the measurement of the terminal hydroxyalkoxy group. The results are shown in Table 1.

[0042]

[Table 1]

[0043]

According to the present invention, an extruded product having excellent mechanical properties and excellent durability in an atmosphere exposed to high temperature for a long time can be obtained.

Claims (1)

[Claims] 1. An oxyalkylene unit represented by the following general formula in a polymer composed of repeating oxymethylene units (—CH ₂ O—): (Ro, R'o: may be the same or different, hydrogen,
It is selected from an alkyl group and a phenyl group. n is an integer of 1 or more, and m = 2 to 6) is 100 mol of an oxymethylene unit.
An extruded product made of polyoxymethylene having a structure in which 0.1 to 0.5 mol is inserted and the terminal group of the polymer is an alkoxy group, a hydroxyalkoxy group or a formate group.