JPH0570538A - Production of oxymethylene copolymer - Google Patents

Abstract

PURPOSE:To obtain the title copolymer excellent in heat stability, mechanical properties, etc., by producing the copolymer under specified conditions and subjecting it to a plurality of specified treatments after the polymerization. CONSTITUTION:A process for producing a copolymer comprising oxymethylene units and other oxyalkylene units by polymerizing a mixture of trioxane with a cyclic ether (e.g. 1,3-dioxolane) in the presence of at least one polymerization catalyst selected from among BF3 (hydrate) and coordination compounds of BF3 with an O-or S-containing organic compound, wherein the polymerization catalyst is deactivated by adding an organophosphorous compound of the formula [wherein R<1> to R<3> are each (halo) alkyl, (substituted) aryl, (substituted) alkoxy, mercapto or (substituted) allyloxy] to the polymerization system after the polymerization. Thereafter a stabilizer (e.g. hindered phenol compound and an HCHO scavenger) and at least one member selected from among water, a water-soluble alcohol and an alkali (alkaline earth) metal salt are added to the system, and the resulting mixture is heated to 100-260 deg.C.

Description

Detailed Description of the Invention

[0001]

INDUSTRIAL APPLICABILITY In the present invention, when trioxane and a cyclic ether are polymerized in the presence of a catalyst to produce oxymethylene, a trivalent organic phosphorus compound is added after the polymerization to deactivate the catalyst. After that, by adding water, water-soluble alcohol, and alkali metal salt or alkaline earth metal salt together with a stabilizer and heating, the heat stability, mechanical properties and surface appearance of the molded product are excellent, and further during melt molding. The present invention relates to a method for producing an oxymethylene copolymer having low odor.

[0002]

2. Description of the Prior Art To obtain an oxymethylene homopolymer or copolymer by bulk polymerization of trioxane alone or trioxane and a cyclic ether is described, for example, in JP-B-44-
No. 5234.

Since the obtained polymer is thermally unstable as it is, in the case of a homopolymer, the terminal group is blocked by esterification or the like, and in the case of a copolymer, the unstable terminal portion is decomposed. Although it is removed and stabilized, it is necessary to deactivate the catalyst and stop the polymerization reaction before that.

That is, an oxymethylene homopolymer or copolymer obtained by cationically polymerizing trioxane or the like gradually undergoes depolymerization unless a catalyst remaining therein is inactivated, resulting in a remarkable decrease in molecular weight. , Becomes a polymer that is extremely thermally unstable.

Regarding the deactivation of the boron trifluoride catalyst, a compound such as alkali metal fluoride which forms a complex compound with a catalyst or a basic substance such as alkali carbonate is added to Japanese Patent Publication No. 48342. Later 0.01-10
A method of moistening with% water is described. Also,
There is also known a method of deactivating a catalyst by polymerizing trioxane or the like in the presence of a catalyst and then adding a trivalent organic phosphorus compound (Japanese Patent Publication No. 55-42085).

[0006]

[Problems to be Solved by the Invention] However, Japanese Patent Publication No. 4
In the basic substance disclosed in JP-A-8-8342, the deactivation effect of the catalyst is insufficient, so that the polymer thermal stability is poor. Further, the polymer in which the catalyst is deactivated by a trivalent organic phosphorus compound disclosed in Japanese Patent Publication No. 55-42085 has high thermal stability, but in recent years, it has a good flowability as the molded product becomes thinner. Is required, and therefore thermal stability is required to withstand higher molding temperatures, and it is not sufficiently satisfactory in that respect.

An object of the present invention is to solve the above problems and to produce an oxymethylene copolymer having excellent thermal stability.

[0008]

That is, the present invention provides a mixture of trioxane and a cyclic ether with boron trifluoride, boron trifluoride hydrate and an organic compound containing an oxygen atom or a sulfur atom. In producing an oxymethylene copolymer containing an oxymethylene unit and another oxyalkylene unit by polymerizing in the presence of at least one polymerization catalyst selected from the group consisting of coordination compounds,
After completion of polymerization, the following general formula

[0009]

[Chemical 2]

(Wherein R ¹ , R ² and R ³ are each an alkyl group, a halogenated alkyl group, an aryl group, a substituted aryl group, an alkoxy group, a substituted alkoxy group, a mercapto group, an aryloxy group or a substituted aryloxy group. After deactivating the polymerization catalyst by adding a trivalent organic phosphorus compound represented by the formula (1)), water, a water-soluble alcohol, and at least one of alkali metal salts or alkaline earth metal salts are added together with a stabilizer. The method for producing an oxymethylene copolymer is characterized in that it is heated in a temperature range of 100 ° C to 260 ° C.

In the present invention, after the polymerization of the oxymethylene copolymer is completed, the catalyst is deactivated with a trivalent organic phosphorus compound, and then water, a water-soluble alcohol, and a stabilizer are added.
It is important to add an alkali metal salt or an alkaline earth metal salt and heat it within a specific temperature range, so that it has excellent thermal stability and mechanical properties, and the surface appearance of the molded product, and also has an odor during molding. It is possible to produce an oxymethylene copolymer having a low content.

Among the cyclic ethers used in the present invention, preferred compounds include ethylene oxide, propylene oxide, 1,3-dioxolane, 1,3-dioxane,
1,3-dioxepane, 1,3,6-trioxocane,
Examples thereof include epichlorohydrin and phenylglycidyl ether, with ethylene oxide, 1,3-dioxolane and 1,3-dioxepane being particularly preferred. The copolymerization amount is usually 0.1 to 10 with respect to the oxymethylene unit.
The amount is in the range of mol%, preferably 0.2 to 6 mol%. If it is too small, the thermal stability of the obtained polymer will be low, and if it is too large, the mechanical strength and moldability will be deteriorated, such being undesirable.

The polymerization catalyst used in the present invention is one selected from the group consisting of boron trifluoride, boron trifluoride hydrate and a coordination compound of boron trifluoride and an organic compound containing an oxygen atom or a sulfur atom. The above compounds are gaseous,
Used as a liquid or a solution of a suitable organic solvent.

Among these catalysts, a coordination compound of boron trifluoride is particularly preferable, and boron trifluoride.
Diethyl etherate and boron trifluoride / dibutyl etherate are preferably used.

The amount of the polymerization catalyst added is preferably in the range of 0.001 to 0.1 part by weight, particularly preferably 0.005 to 0.05 part by weight, based on 100 parts by weight of trioxane.

Various devices for polymerizing trioxane alone or trioxane and a cyclic ether in bulk are known, but the polymerization of the present invention is not particularly limited by the device, and bulk polymerization or an organic solvent such as cyclohexane is known. It can also be applied to a polymerization reaction carried out in the presence of.

In the bulk polymerization, an apparatus having a strong stirring ability and controlling the reaction temperature is preferably used because rapid solidification and heat generation occur during the polymerization.

As a bulk polymerization apparatus having such a performance, a kneader having a sigma type stirring blade, a cylindrical parel as a reaction zone, and a screw having coaxial and many interrupted peaks in the parel are provided. A mixer that operates so that the interrupted part and teeth protruding on the inner surface of the parell mesh, a long case with a jacket for heating or cooling, a conventional screw extruder with a pair of mutually parallel parallel screws, For example, a self-cleaning mixer that has multiple paddles on the horizontal stirring shaft and that rotates when the shafts are simultaneously rotated in the same direction while maintaining a slight clearance between the mating paddle surface and the inner surface of the case. Can be mentioned.

In bulk polymerization, solidification rapidly occurs at the initial stage of the polymerization reaction, and thus strong stirring ability is required. However, once pulverized, large stirring ability is not required thereafter, so bulk polymerization is not required. The process may be divided into two steps.

The bulk polymerization reaction temperature is preferably in the range of 30 to 120 ° C, particularly preferably in the range of 60 to 90 ° C.

At the beginning of the polymerization, the temperature in the polymerization reaction device tends to rise due to the reaction heat and the frictional heat caused by solidification. Therefore, the reaction temperature should be controlled by passing cooling water through the jacket. Is desirable.

The trivalent organophosphorus compound which deactivates the boron trifluoride-based catalyst and terminates the polymerization reaction used in the present invention is represented by the above general formula, and typical ones are triethylphosphine and diethyl. Butylphosphine, tri-n-butylphosphine, dimethylphenylphosphine, methyldiphenylphosphine, methylbenzylphenylphosphine, ethyldicyclohexylphosphine,
Isopropyl diphenylphosphine, n-butyldiphenylphosphine, cyclohexyldiphenylphosphine, triphenylphosphine, tricyclohexylphosphine, tribenzylphosphine, ethyl dipropylphosphinate, butylethylethylphosphinate ethyl, methylphenylphosphinate ethyl, diphenylphenylphosphinate Dimethyl ethylphosphonous acid, Diethyl ethylphosphonous acid, Diphenyl ethylphosphonous acid, Triethyl phosphite, Tri-n-propyl phosphite, Triphenyl phosphite, Tritolyl phosphite, Tristearyl trithiophosphite And triphenylphosphine, triphenyl phosphite and tritolyl phosphite are particularly preferable. These may be added as they are, but may be added as a solution or suspension of an organic solvent in order to promote contact with the polymerization catalyst. Examples of the organic solvent at that time include aromatic hydrocarbons such as benzene, toluene and xylene, aliphatic hydrocarbons such as n-hexane, n-heptane and cyclohexane, chloroform, dichloromethane, 1,2-dichloroethane. Examples thereof include halogenated hydrocarbons, ketones such as acetone and methyl ethyl ketone.

The addition amount is usually 0.001 to 5 parts by weight, preferably 0.01 to 3 parts by weight, based on 100 parts by weight of the oxymethylene copolymer. If the amount is too small, there is no effect of improving the thermal stability of the oxymethylene copolymer, and if the amount is too large, the bleeding phenomenon is exhibited or the mechanical properties are deteriorated, which is not preferable.

The amount of water used in the present invention is usually 0.01 to 1 with respect to 100 parts by weight of oxymethylene copolymer.
It is 00 parts by weight. It is preferably 0.1 to 10 parts by weight, and more preferably 0.5 to 5 parts by weight. If the amount is too small, there is no effect of improving the thermal stability of the oxymethylene copolymer, and if the amount is too large, it is not preferable because the production becomes difficult.

Typical water-soluble alcohols used in the present invention include methyl alcohol, ethyl alcohol, n
-Propyl alcohol, isopropyl alcohol and the like. Oxymethylene copolymer 10 is usually added.
It is usually 0.01 to 100 parts by weight, preferably 0.1 to 10 parts by weight, and more preferably 0.5 to 5 parts by weight with respect to 0 parts by weight. When the amount is too small, the effect of improving the thermal stability of the oxymethylene copolymer is small, and when the amount is too large, the production is difficult, which is not preferable.

The alkali metal salts or alkaline earth metal salts used in the present invention include alkali metal or alkaline earth metal hydroxides, carbonates, bicarbonates, phosphates, borates, silicates and the like. Inorganic weak acid salt, acetate, oxalate, formate, benzoate, terephthalate, isophthalate, phthalate, fatty acid, and other organic acid salts, methoxide, ethoxide, n-butoxide, sec-butoxide Examples thereof include alkoxides such as tert-butoxide, and phenoxides. Among them, hydroxides, carbonates, acetates, and fatty acid salts are preferably used.

Examples of the alkali metal or alkaline earth metal include lithium, sodium, potassium, cesium, magnesium, calcium, strontium, barium and the like, among which lithium, sodium, potassium, magnesium and calcium are preferably used.

Specifically, calcium hydroxide, magnesium hydroxide, sodium carbonate, calcium acetate, calcium stearate, 12-hydroxy calcium stearate and the like are particularly preferable.

In the present invention, one or more of the alkali metal salts and alkaline earth metal salts are added as described above. The addition amount is usually 0.001 to 5 parts by weight based on 100 parts by weight of oxymethylene copolymer, and 0.005 to 5 parts by weight.
2 parts by weight is preferred. When the amount is too small, the effect of improving the thermal stability of the oxymethylene copolymer is small, and when the amount is too large, the bleeding phenomenon is exhibited or the mechanical properties are deteriorated, which is not preferable.

Examples of the stabilizer used in the present invention include a hindered phenol compound and a formaldehyde scavenger, which are preferably used in combination.

Specific examples of the hindered phenol type compound include 2,6-di-t-butyl-4-methylphenol and triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-methylphenol bis [3- (3-t-butyl-5-methyl-4-methyl- Hydroxyphenyl) propionate], 1,6-hexanediol-bis [3-
(3,5-di-t-butyl-4-hydroxyphenyl)
Propionate], pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], N, N′-hexamethylenebis (3,5-di-t-butyl-4) -Hydroxyhydrocinnamamide), 2-t-butyl-6- (3'-t-butyl-5'-methyl-2'-hydroxybenzyl) -4-
Methylphenyl acrylate, 3,9-bis [2- {3
-(3-t-Butyl-4-hydroxy-5-methylphenyl) propionyloxy} -1,1-dimethylethyl] -2,4,8,10-tetraoxaspiro [5.
5] Examples include undecane. Molecular weight 40
Triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate] which is a compound of 0 or more, pentaerythrityl-tetrakis [3- (3,5-di-t- Butyl-4-hydroxyphenyl) propionate] is particularly preferred. When a hindered phenol compound is used, the amount added is usually 0.001 to 5 parts by weight, preferably 0.01 to 3 parts by weight, based on the oxymethylene copolymer. If it is too small, the effect of improving the thermal stability of the oxymethylene copolymer is small, and if it is too large, the bleeding phenomenon is observed, which is not preferable.

Examples of the formaldehyde scavenger used in the present invention include polyamide compounds, ethylene / vinyl alcohol copolymers, urethane compounds, pyridine derivatives, pyrrolidone derivatives, urea derivatives, triazine derivatives, hydrazine derivatives and amidine compounds. , Specifically, nylon 6, nylon 66, nylon 6/6
6 binary copolymer, nylon 6/12 copolymer, nylon 6/66/610 ternary copolymer, nylon 6/66/6
10/12 quaternary copolymer, melamine, benzoguanamine, acetoguanamine, N-methylolmelamine, N,
N′-dimethylolmelamine, N, N ′, N ″ -trimethylolmelamine, dicyandiamide and the like are preferable.
Among these, nylon 6/66/610/12 quaternary copolymer and melamine are particularly preferable.

When the formaldehyde scavenger is used, the addition amount is usually 0.001 to 5 parts by weight, preferably 0.
0 to 1 part by weight. If the amount is too small, the thermal stability of the obtained composition is insufficient. If the amount is too large, it is not preferable because the composition may be precipitated on the surface or the composition may be colored.

Further, the composition of the present invention contains calcium carbonate, barium sulfate, clay, titanium oxide, silicon oxide, mica powder, fillers such as glass beads, carbon fiber, and glass as long as the effects of the present invention are not impaired. Reinforcing agents such as fibers, ceramic fibers, aramid fibers, potassium titanate fibers,
Colorants (pigments, dyes), nucleating agents, plasticizers, release agents such as ethylene bis-stearamide, polyethylene wax,
Conductive agents such as carbon black, benzophenone compounds, light stabilizers such as benzotriazole compounds,
Additives such as a pressure-sensitive adhesive, a lubricant, a hydrolysis resistance improver, and an adhesion aid can be optionally contained.

Further, the oxymethylene copolymer of the present invention is
After polymerizing a mixture of trioxane and cyclic ether with a polymerization catalyst and deactivating the polymerization catalyst by adding a trivalent organic phosphorus compound, water, a water-soluble alcohol, and an alkali metal or alkali with a stabilizer. It is manufactured by adding at least one of earth metal salts and kneading by heating. The heating temperature needs to be 100 to 260 ° C., preferably 1
It is in the range of 70 ° C to 260 ° C.

The stabilizer, water, water-soluble alcohol, alkali metal salt or alkaline earth metal salt may be added one by one, or may be added all at once. Also, these additives may be added as they are,
You may add as a solution of an organic solvent. Examples of the organic solvent at that time include aromatic hydrocarbons such as benzene, toluene and xylene, aliphatic hydrocarbons such as n-hexane, n-heptane and cyclohexane, chloroform, dichloromethane, 1,2-1,2- Examples thereof include halogenated hydrocarbons such as dichloroethane, ketones such as acetone and methyl ethyl ketone.

Examples will be described below, but the present invention is not limited thereto.

[0038]

The present invention will be described below with reference to examples. All percentages and parts in the examples are by weight.

The MI value, the thermal decomposition rate K250, the polymer melting point Tm and the crystallization temperature Tc, the mechanical properties and the surface appearance of the molded products shown in the examples and comparative examples were measured as follows. ..

Molding: Using an injection molding machine having a mold clamping pressure of 60 tons, a cylinder temperature of 190 ° C. and a mold temperature of 65.
The ASTM No. 1 dumbbell test piece and the Izod impact test piece were injection-molded at a setting temperature of 50 ° C. and a molding cycle of 50 seconds. At this time, the odor of the molded product is ◯: Almost no, Δ: Slightly strong,
X: Strongly evaluated in three grades.

The surface condition of the ASTM No. 1 dumbbell test piece obtained by the above injection molding was observed with the naked eye and smooth: ○,
The evaluation was made in three grades, that is, slightly rough: Δ and rough: ×.

MI value: Measured at a temperature of 190 ° C. and a load of 2160 grams according to the ASTM D-1238 method using pellets dried in a hot air oven at 80 ° C. for 3 hours.

Mechanical properties: AS obtained by the above injection molding
Using the TM1 dumbbell test piece, ASTM D-638
The tensile strength was measured according to the method, and the impact strength was measured according to the ASTM D-256 method using an Izod impact test piece.

Heat decomposition rate K250: K250 is 250 ° C
Means the decomposition rate when left to stand for a certain period of time. Using a thermobalance device, a sample of about 10 mg was placed under a nitrogen atmosphere,
It was left at 250 ° C., and calculated by the following formula.

K250 = (W0−W1) × 100 / W0 Here, W0 means the sample weight before heating and W1 means the sample weight after heating. As the thermobalance device, TG / DTA200 manufactured by Seiko Denshi KK was used.

Polymer melting point Tm, crystallization temperature Tc: Using a differential scanning calorimeter, the temperature is raised at a heating rate of 10 ° C./min in a nitrogen atmosphere, and after measuring the polymer melting point Tm, 10 ° C. / The temperature was lowered in minutes, and the crystallization temperature Tc was measured.

In Examples and Comparative Examples, oxymethylene crude polymer (POM-1) produced by the following method was used.

.Oxymethylene crude polymer (POM-1)
Manufacture of twin-screw extruder type polymerization machine (100 mmφ, cylinder length (L) / cylinder diameter (D) = 10.2) with trioxane (22.5 kg / h) and 1,3-dioxolane (70
0 g / h), and 100 ppm of boron trifluoride diethyl etherate (2.5% benzene solution) and 500 ppm of methylal were respectively fed to trioxane to carry out continuous polymerization. Polymerization was performed by controlling the outer jacket temperature to 60 ° C. and rotating at 100 rpm. Methylal as a molecular weight regulator was dissolved in trioxane. Further, a premixing zone was provided so that 1,3-dioxolane and the catalyst solution were premixed immediately before being supplied to the kneader. Polymer as white fine powder 2
Obtained at 2.3 kg / h.

The trivalent organic phosphorus compound, hindered phenol compound, alkali metal salt or alkaline earth metal salt and formaldehyde scavenger used in Examples and Comparative Examples are as follows.

A-1: triphenylphosphine A-2: triphenyl phosphite A-3: tritolyl phosphite B-1: calcium stearate B-2: 12-calcium hydroxystearate B- 3: Sodium carbonate B-4: Calcium hydroxide B-5: Magnesium hydroxide O-1: Triethylene glycol-bis [3- (3-
t-butyl-5-methyl-4-hydroxyphenyl) propionate] (Ciba Geigy "Irganox" 24
5) O-2: 1,6-hexanediol-bis [3-
(3,5-di-t-butyl 4-hydroxyphenyl) propionate] (Ciba Geigy "Irganox" 25
9) O-3: pentaerythrityl-tetrakis [3-
(3,5-di-t-butyl-4-hydroxyphenyl)
Propionate] (Ciba Geigy "Irganox" 1
010.T-1: Polyamide 6/66/610/12 quaternary copolymer (copolymerization composition 6/66/610/612 = 22/1
2/16/50 (wt%) T-2: Polyamide 6/66/610/12 quaternary copolymer (copolymerization composition 6/66/610/12 = 33/17
/ 33/17 (wt%))-T-3: melamine-T-4: dicyandiamide Examples 1-10, Comparative Examples 1-9 Various trivalents with respect to 5 kg of oxymethylene crude polymer (POM-1). The organophosphorus compound of was added as a benzene solution of 15 to 20% in the ratio shown in Tables 1 and 2, and the catalyst was deactivated by stirring for 10 minutes in a Henschel mixer.
Water, water-soluble alcohol, and various alkali metal salts and alkaline earth metal salts are added to this together with a stabilizer, and the temperature is 220 ° C. using a vented twin-screw 45 mmφ extruder manufactured by Ikegai Iron Works, and the degree of vacuum at the vent is 10 mm. Melt extrusion kneading was performed at torr. The resulting polymer was extruded as a strand and pelletized by a cutter. After drying the pellets in a hot air circulation oven at 80 ° C. for 5 hours,
MI measurement, thermal decomposition rate measurement, and molding were performed to measure mechanical properties. These results are summarized in Tables 3 and 4.

[0051]

[Table 1]

MeOH: methyl alcohol EtOH: ethyl alcohol n-PrOH: n-propyl alcohol

[0053]

[Table 2]

[0054]

[Table 3]

Appearance of molded product ○: Smooth Δ: Slightly rough ×: Rough Odor of molded product ○: Almost no, Δ: Slightly strong, ×:
strong

[0056]

[Table 4]

Appearance of molded product ○: Smooth Δ: Slightly rough ×: Rough Odor of molded product ○: Almost no, Δ: Slightly strong, ×:
strong

[0058]

EFFECTS OF THE INVENTION The oxymethylene copolymer produced according to the present invention is excellent not only in thermal stability but also in mechanical properties, so that it can be used in a wide range of applications such as machine mechanism parts, automobile parts, and electric / electronic parts. .

Claims (2)

[Claims] 1. A mixture of trioxane and a cyclic ether is selected from the group consisting of boron trifluoride, boron trifluoride hydrate, and a coordination compound of boron trifluoride and an organic compound containing an oxygen atom or a sulfur atom. When an oxymethylene copolymer containing an oxymethylene unit and another oxyalkylene unit is produced by polymerizing in the presence of at least one polymerization catalyst, the following general formula: (Wherein R ¹ , R ² and R ³ are each an alkyl group, a halogenated alkyl group, an aryl group, a substituted aryl group, an alkoxy group, a substituted alkoxy group, a mercapto group, an aryloxy group or a substituted aryloxy group). After deactivating the polymerization catalyst by adding the represented trivalent organic phosphorus compound, water, a water-soluble alcohol, and at least one of alkali metal salts or alkaline earth metal salts are added together with a stabilizer, and the mixture is heated to 100 ° C. A method for producing an oxymethylene copolymer, which comprises heating in a temperature range of ˜260 ° C. 2. The method for producing an oxymethylene copolymer according to claim 1, wherein a hindered phenol compound and a formaldehyde scavenger are used as the stabilizer.