WO2000047646A1

WO2000047646A1 - Process for continuously producing polyacetal resin

Info

Publication number: WO2000047646A1
Application number: PCT/JP2000/000750
Authority: WO
Inventors: Noriyuki Sugiyama
Original assignee: Polyplastics Co., Ltd.
Priority date: 1999-02-10
Filing date: 2000-02-10
Publication date: 2000-08-17
Also published as: JP2000230026A

Abstract

A process for continuously producing a polyacetal resin which comprises adding a comonomer to trioxane to conduct cationic polymerization in the presence of a specific silane compound. By the process, a high-quality polyacetal resin can be continuously produced industrially and stably for long in high yield.

Description

Description Continuous production method of polyacetal resin

TECHNICAL FIELD The present invention relates to a continuous production method of a polyacetal resin by cationic polymerization, and more particularly, to a method for industrially and continuously producing a polyacetal resin of a copolymer having a small number of unstable molecular terminals in a high yield in an industrially stable manner. Background art

Polyacetal resin has excellent balance among mechanical properties, chemical resistance, slidability, etc., and is easy to mold, making it a typical engineering plastic material. It is widely used mainly in various other mechanical parts.

In recent years, along with the expansion of the range of use, the required performance of polyacetal resin has been enhanced, and the demand for high quality and low cost of the resin has been high, and high-quality polyacetal resin has been obtained in high yield. There is a need for a manufacturing method. In particular, when the production conditions are set for high yield, the ratio of the terminal end of the unstable molecule in the resin molecule tends to increase, so that both requirements are satisfied in a well-balanced manner. There is a strong need for an improved manufacturing method.

Conventionally, in order to obtain a high yield of polyacetal resin, the type of catalyst has been studied and the method of adding the catalyst has been improved. As typical examples, JP-A-2-6529, JP-A-4-165412, JP-A-4-65413 and JP-B-8-30103 disclose a cyclic ether and a polymerization catalyst in advance when producing a polyacetal resin. And a method of continuously adding the contacted mixture to trioxane. In addition, JP-A-59-227916, JP-A-60-1216 and JP-A-53-111087 disclose in order to obtain a high quality polyacetal resin, A method has been proposed in which a sterically hindered phenolic antioxidant is added together with the monomer, and a method in which an organic trivalent phosphorus compound is added and mixed in advance to a monomer to be subjected to polymerization. However, the quality of each method tends to deteriorate under high yielding production conditions, and no method has yet been proposed to satisfy both performances in a balanced manner.

Further, Japanese Patent Application Laid-Open No. 641-11117 discloses a technique of introducing a silicone oil having a reactive epoxy group into a polymerization system at the time of producing a polyacetal resin, and synthesizing a copolymer of polyacetal and silicone oil. Proposed. Since the silicone oil used in this proposal has very few functional groups that react with water and formic acid, there is room for improvement in improving the quality of polyacetyl resins. In view of such circumstances, the present invention enables continuous production of a high-quality polyacetal resin, in particular, a copolymer polyether resin, by a cationic polymerization method with high yield and industrially stable for a long period of time. It is intended to provide a method. Disclosure of the invention

The present inventors have conducted intensive studies to achieve the above object, and as a result, a method of adding a specific silane compound together with these monomers at the time of copolymerization of a specific main monomer and a comonomer, or a method in which the above monomer to be subjected to polymerization is prepared in advance. If the method of adding and mixing a specific silane compound is used, the specific silane compound can reduce the amount of formic acid and water, which are factors that reduce the catalytic activity at the time of polymerization. A high-concentration catalyst amount enables high-yield polymerization, and the silane compound has reactivity with the hydroxy terminal of a polymer generated by a side reaction of the catalyst, thereby enabling high quality. The inventors have found that the present invention can be solved, and have completed the present invention.

That is, the present invention provides a method for continuously producing a copolymer polyacetal resin by adding and supplying a cyclic ether and / or cyclic formal as a comonomer to trioxane as a main monomer and performing cationic polymerization. Polyacetal tree coexisting with at least one selected from the group of silane compounds represented by (IV) To provide a continuous method for producing fats,

0—R 16

(In the formula, R ¹ , R ⁵ , R ⁶ , R ⁹ , R ¹⁰ , R ", R ¹³ , R ¹⁴ , R ' ⁵ and R ¹⁶ are a hydrogen atom and a hydrocarbon residue having 1 to 6 carbon atoms. R ² , R ³ , R ⁴ , R ⁷ , R ⁸ and R ′ ² are a hydrogen atom, a hydrocarbon residue having 1 to 22 carbon atoms, An atom independently selected from the group consisting of hydrocarbon residues having a functional group containing one or more atoms each independently selected from the group consisting of fluorine, oxygen, nitrogen, iodide and phosphorus; or Indicates a residue.)

Further, in the present invention, at least one selected from the group of the silane compounds represented by the above general formulas (I) to (IV) is added and mixed in advance with at least one of trioxane, cyclic ether and / or cyclic formal. An object of the present invention is to provide a method for continuously producing a polyacetyl resin. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, various embodiments of the continuous production method of the polyacetal resin of the present invention will be described. This will be described in detail with reference to FIG. The polyacetal resin according to the present invention is obtained by adding a cyclic ether and / or cyclic formal as a comonomer to trioxane as a main monomer and cationically copolymerizing the same. At this time, a specific silane compound for removing a trace amount of formic acid / water component contained as an impurity in the copolymerization monomer is blended as a scavenger, and Brenstead acid and / or Lewis acid is used as a polymerization catalyst, and cationic polymerization is performed. This is a method for producing a copolymer polyacetal resin. In the present invention, trioxane is used as a main monomer, and a cyclic ether and / or cyclic formal is used as a comonomer.

Examples of the cyclic ether include ethylene oxide and oxetane. Examples of the cyclic formal include glycidyl ether compounds such as 1,4-butanediol diglycidyl ether, butyl glycidyl ether, and octyldaricidyl ether; 1,3-dioxolan; 1,3,5-trioxepane; , 3-Dioxane, 4-Methyl_1,3-Dioxolane, 6-Methyl-1,3,5-Trioxepane, 1,4-Butanediolformal, 4-Ethyl-1,3-Dioxolane, 6-Ethyru-1 , 3,5-trioxepane, 4-methyl-1,3-dioxane, 5-methyl-1,3-dioxane, 1,5-pentenediolformal, 4-propyl_1,3-dioxolan, 6- Propyl-1,3,5-trioxepane, 41-ethyl-1,3-dioxane, 5-ethyl-1,3-dioxane, 1,6-hexanediol formal, 4-butyl 1, 3-Jiokisoran, 6-heptyl - 1, 3, 5-trioxepane, 4-propyl one 1, 3-Jiokisan, 5-propyl one 1, 3-Jiokisan and the like.

The amount of these comonomers to be used is preferably 20% by weight or less, particularly 0.1 to 15 times, based on the trioxane of the main monomer, in consideration of the rigidity and chemical resistance of the molded article. % Is preferred. As the specific silane compound used in the production method according to the present invention, at least one selected from the group of silane compounds represented by the general formulas (I) to (IV) is used.

Examples of the silane compound represented by the general formula (I) include monoalkoxysilanes such as trimethylmethoxysilane, trimethylethoxysilane, triethylmethoxysilane, and triethylethoxysilane, and are represented by the general formula (II). Examples of the silane compound include dialkoxysilanes such as dimethyldimethoxysilane, dimethylethoxysilane, dimethyldimethoxysilane, and dimethylethylethoxysilane. Examples of the silane compound represented by the general formula (III) include triethoxysilane, trimethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, methyltripropoxysilane, methyltributoxysilane, methyltriphenoxysilane. Saturated alkyltrialkoxysilanes such as sicilan, octyltriethoxysilane, octadecyltriethoxysilane, octadecyltrimethoxysilane, propyltriethoxysilane, hexyltriethoxysilane, pentyltriethoxysilane, etc. Ryltriethoxysilane, α-aminopropyltriethoxysilane, α- (2-aminoethyl) aminopropyltrimethoxysilane, anilinopropyltrimethoxysilane, methacryloxypropyltrimethoxysilane, 3 Glycidyloxypropyl trimethoxysilane, tris (2-methoxyethoxy) vinylsilane, 3-trifluoroacetoxypropyltrimethoxysilane, biertrimethoxysilane, vinyltriethoxysilane, vinyltributoxysilane, Preferred examples include unsaturated and substituted alkoxytrialkoxysilanes such as phenyltriethoxysilane, phenyltrimethoxysilane and benzyltriethoxysilane.

Further, as the silane compound represented by the general formula (IV), tetramethoxysilane, tetraaryloxysilane, tetraethoxysilane, Single tetraalkoxysilanes such as tetrabutoxysilane, tetrakis (2-methoxyethoxy) silane, and tetraphenoxysilane, as well as methoxytriethoxysilane, dimethoxydiethoxysilane, trimethoxyethoxysilane, and hexyloxytrimethoxysilane And the like.

The silane compounds used in the present invention are not limited to those exemplified above, but among those exemplified above, dimethyldimethoxysilane, dimethylmethylethoxysilane, getyldimethoxysilane, dimethylethylmethoxysilane, Kutadecyltriethoxysilane, octadecyltrimethoxysilane, methacryloxypropyltrimethoxysilane, 3-daricyloxypropyltrimethoxysilane, tris (2-methoxyethoxy) vinylsilane, tetraethoxysilane, tetrapropoxysilane Tetrabutoxysilane and tetrakis (2-methoxyethoxy) silane are particularly preferred.

The method of adding the silane compound according to the present invention is not particularly limited, and the silane compound may be supplied to the polymerization machine simultaneously with the main monomer trioxane, the comonomer cyclic ether or cyclic formal, or may be supplied in advance to the main monomer and / or The silane compound may be added to a comonomer and mixed, and then subjected to copolymerization.

However, in order to start exerting the effect of the present invention by adding the silane compound from the early stage of the polymerization, the addition of the silane compound is preferably performed before the addition of the polymerization catalyst. A method of maintaining the temperature at 0 ° C for 1 second or more is particularly preferable. Although the reason for this is not clear, the mixing state of the silane compound in the main monomer and / or comonomer becomes more uniform, and as a result, the reaction with the internal impurities and moisture proceeds, and the catalyst is deactivated. It is considered that the ratio is further reduced.

The amount of the silane compound used in the present invention is preferably from 1 to 500 ppm by weight, more preferably from 10 to 200 ppm by weight, based on trioxane as the main monomer. It is 50 to 1000 weight ppm. If the amount of the silane compound is too small, as in the case where the amount is less than 1 ppm by weight, it may not be possible to capture the formic acid / water, which is an impurity in the monomer, and it is said that a sufficient effect is obtained. can not cut. On the other hand, when the amount is excessive, such as when the content exceeds 500 ppm by weight, the silane compound vaporizes and evaporates from the polyacetal resin in a later step in the production of the polyacetal resin, and the silane compound is concentrated following the adhesion to the piping. As a result, problems such as contamination of the piping into the product bellet may occur. Next, a general cation-active catalyst is used as a polymerization catalyst used in the present invention. Hereinafter, the cation-active catalyst will be described by way of example.

(1) Lewis acids; in particular, halides such as boron, tin, titanium, phosphorus, arsenic, and antimony are suitable. Specific examples include boron trifluoride, tin tetrachloride, titanium tetrachloride, phosphorus pentachloride, and pentafluoride. Examples thereof include phosphorus, arsenic pentafluoride, and antimony pentafluoride. Further, compounds such as complex compounds thereof (for example, coordination compounds with organic compounds such as ether compounds) or salts thereof can also be used.

(2) Protonic acid; specific examples include trifluoromethanesulfonic acid, perchloric acid and the like.

(3) Esters of protonic acid; in particular, esters of perchloric acid and lower aliphatic alcohols can be used. Specific examples thereof include tertiary butyl perchlorate.

(4) Protic acid anhydrides; in particular, mixed anhydrides of perchloric acid and lower aliphatic carboxylic acids can be used, and specific examples thereof include acetyl chloride.

(5) In addition, isopolyacid, heteropolyacid (for example, phosphomolybdic acid), or triethyloxenoxahexafluorophosphato, triphenylmethylhexafluoroarsenate, acetylhexafluoroborate And the like.

Among the catalysts used in the present invention, among those exemplified above, boron trifluoride or a coordination compound of the boron trifluoride and an organic compound (for example, ethers) is the most common, and It is. The boron trifluoride may be used by mixing with an inert gas such as nitrogen, and the boron trifluoride coordination compound may be used after being diluted once with an organic solvent or the like. The basic molecular structure of the polyacetal resin obtained by the production method according to the present invention is not particularly limited, and includes those having a branched structure or a crosslinked structure, those having a block component introduced, and the like. The molecular weight or melt viscosity is not limited as long as it can be melt-molded, but the melt index (MI) is 0.:!~lOO gZl Omin (ASTM D 1238-57T E) Are preferred. In the production method of the present invention, in principle, a main monomer, a comonomer, a specific silane compound, and a polymerization catalyst are used as main raw materials. It is also possible to use them together.

As a component for adjusting the molecular weight, a chain transfer agent that does not form an unstable molecular terminal portion, that is, a compound having an alkoxy group such as methylal, methoxymethylal, dimethoxymethylal, trimethoxymethylal, and oxymethylenedi-n-butyl ether is used. Is exemplified.

Examples of components used when it is necessary to form a branched or crosslinked structure in the polyacetal resin according to the present invention include ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, and 1,4-butanediol diglycol. Sidyl ether, hexamethylene glycol diglycidyl ether, resorcinol diglycidyl ether, bisphenol A diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene dalicol diglycidyl ether, polybutylene glycol diglycidyl ether, glycerin and its Inducers, pen-erythritol and its derivatives, and the like.

The amount of the component for adjusting the molecular weight is preferably 0.5% by weight or less, particularly preferably 0.4% by weight or less, based on the trioxane. The amount of the component for forming the branched or crosslinked structure is preferably at most 0.3% by weight, particularly preferably at most 0.2% by weight, based on the trioxane. These components for adjusting the molecular weight, the components for forming the branched or crosslinked structure, and the like may be added to either the trifluoroxane or the comonomer, and may be added after being diluted once with another organic solvent or the like. You may. As a polymerization machine suitable for continuous production of the polyacetone resin according to the present invention, a mixing means such as a screw, a paddle, a disk, a pin, and a blade is directly connected to two rotary drive shafts provided in a barrel. Examples include a kneader and a co-kneader type polymerization machine.

When the polyacetal resin according to the present invention is produced in these polymerization machines, the polymerization temperature is preferably in the range of 65 to 135 ° C.

The deactivation of the polymerization catalyst remaining in the resin after the polymerization of the polyacetal resin is performed by adding a basic compound or an aqueous solution thereof to the reaction product discharged from the polymerization machine after the polymerization reaction or the reaction product still in the polymerization machine. In addition it can be done. This inactivation is usually due to neutralization.

As the basic compound for deactivating the polymerization catalyst, in addition to ammonia, amines such as triethylamine, triptylamine, triethanolamine, and triethanolamine, or hydroxides of alkali metals and alkaline earth metals, Other known catalyst deactivators are used.

After the polymerization and deactivation steps, the polymerization product is further subjected to washing, separation and recovery of unreacted monomers, drying and the like, if necessary, by a conventionally known method. Further, if necessary, a stabilization treatment such as decomposition removal of terminal portions of unstable molecules or sealing is performed by a known method such as blending of various stabilizers. Examples of the stabilizer used herein include one or more of a hindered phenolic compound, a nitrogen-containing compound, an alkali or alkaline earth metal hydroxide, an inorganic acid, and a carboxylate. Those used in combination can be mentioned. In addition, the polyacetal resin according to the present invention may contain, if necessary, a general additive to the thermoplastic resin, for example, coloring of a dye, a pigment or the like, as long as the properties of the resin are not impaired. Agents, lubricants, nucleating agents, release agents, antistatic agents, modifiers such as surfactants, organic polymer materials, inorganic or organic fibrous, powdery, plate-like fillers, etc. Two or more can be added. Hereinafter, the present invention will be described specifically, but the present invention is not limited to these examples.

(Examples 1 to 9)

Using a continuous mixed polymerization machine that has a jacket with a cross section with two circles partially overlapped with a jacket through which heat (cooling) medium passes, and a rotary shaft with two paddles, While rotating the two rotating shafts at 150 ppm, the trioxane mixture, that is, the specific silane compound shown in Table 1 in advance at the ratio shown in Table 1 (% by weight of trioxane) was supplied from one end of the supply port. The mixture was kept at 80 ° C for 30 minutes, and 4.0 mol 1% (based on trioxane) of a specific cyclic formal shown in Table 1 as a comonomer and 0.08 wt. % (Vs. trioxane) of the trioxane mixture was continuously fed.

Subsequently, cationic / bulk polymerization was continuously performed while continuously supplying boron trifluoride (30 weight parts per million (based on trioxane)) to the polymerization machine from the supply port.

After adding the trioxane, comonomer, and methylal to the polymerization machine, continuous cation and bulk polymerization were also performed when boron trifluoride and the specific silane compound were simultaneously and continuously supplied to the polymerization machine.

The reaction product discharged from the outlet of the polymerization machine is immediately passed through a crusher, added to an aqueous solution at 60 ° C containing 0.05% by weight of triethylamine, pulverized into particles, and the catalyst is deactivated at the same time. Then, after separation, washing and drying, the desired polyacetal resin was obtained. Table 1 shows the polymerization yield based on the feedstock, the Ml value that is a measure of quality, and the proportion (thermal weight loss) of the portion decomposable into formaldehyde at 200 ° C or less relative to the total weight. Was. (Comparative Examples 1-3)

Under the conditions that no specific silane compound used in the examples was used and no other silane compounds were used, the other conditions relate to the production and properties of the polyacetyl resin obtained in the same manner as in the examples. The values are also shown in Table 1. The methods for evaluating the polymerization yield and the resin properties (MI, thermal weight loss rate) of the polyacetal resin are summarized below.

(1) Polymerization yield (%)

When the continuous polymerization process was in a steady state, the catalyst was deactivated for the polyatal resin collected within a certain period of time, the washed sample was dried at 50 ° C for 24 hr, weighed, and the obtained value was taken as the above-mentioned collection time. It was divided by the total weight of the feedstock added to the polymerization machine within the same time and expressed as a percentage.

(2) M.I (g / 1 0m i n)

To the dried polyacetal resin was added 0.5% by weight of an antioxidant, triethylene glycol bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate], based on the polyacetal resin. And 0.5% by weight of melamine were blended and thoroughly mixed. The resulting mixture was retained in a cylinder of a melt indexer maintained at 190 ° C for 15 minutes, and then 2,160 g of the mixture was melted. The Ml value was obtained by converting the weight of the resin obtained by extruding from a capillar having a load of 2 mm ΦΧ8 mm into the amount of extrusion for 10 minutes.

(3) Thermal weight loss rate (%)

After the drying in (1), 50% by weight, based on the polyacetal resin, of sufficiently dried powdered magnesium oxide is added to the finely pulverized polyacetal resin, and the powders are sufficiently mixed to obtain a mixture. The sample is first kept at 50 ° C for 30 minutes using TGA (thermogravimetric analysis) under a nitrogen atmosphere, and the sample weight is measured. Subsequently, the temperature is raised to 200 with 10 O ^ Zmin, kept at that temperature for 1 hour, and the weight reduction value of the sample is measured. Next, the temperature was further raised to 450 ° C by 100 ° C At 30 ° C for 30 minutes to completely degrade the resin part and measure the weight loss relative to the initial sample weight.

The weight loss value obtained after holding at 200 ° CZ for 1 hour was divided by the weight loss value shown after holding at 450 ° CZ for 30 min to obtain a thermal weight loss rate.

* Name of comonomer (all are cyclic formal)

a— 丄! · · · ·!, 3—Dioxolan

a-2 3-dioxane

a-3 4-butanediol formal

* 2 Name of silane compound

b— 1 · ♦ [An embodiment of the formula (IV), which is represented by the following formula (V). ]

b-2 Methyltriethoxysilane [One embodiment of the formula (III), which is represented by the following formula (VI). ]

b-3 getyl ethoxysilane [an embodiment of the formula (II),

It is represented by the following formula (VII). ]

b-4 3-glycidyloxypropyldimethylmethoxysilane [an embodiment of the formula (I), which is represented by the following formula (VIII)] ]

* 3 This shows the case where the silane compound is added to the polymerization system simultaneously with the addition of the catalyst without prior mixing with trioxane.

CH ₃ C H2-O S i-O-CH ₂ CH ₃ (V)

CH ₃ CH ₂ -0- S i-O-C H2 CH _S (VI)

C Hs

CH ₃ C H2-O S i — C na C Hs (VII)

CH ₃

CH ₃ O-Si i CH ₃ 0 (VIII)

0- C H2 C H2 C H2 O C H2 C H- C H2

Industrial applicability

According to the continuous production method of the polyacetal resin of the present invention, a high-quality polyacetal resin having a small number of unstable molecular terminals can be obtained in a high yield and industrially for a long period of time.

In addition, the polyacetal resin obtained by the present invention is particularly excellent in molding processability, and also excellent in balance of mechanical properties, chemical resistance, slidability, etc. like ordinary polyacetal resin, so that injection molding is performed. In addition to products, it is useful in various fields such as extrusion molded products, professional molded products, and foam molded products.

Claims

The scope of the claims

1. A cyclic ether and / or cyclic formal as a comonomer is added and supplied to trioxane as a main monomer, and is subjected to cation polymerization to continuously produce a copolymer polyester resin. A method for continuously producing a polyacetal resin, wherein the method is carried out in the presence of at least one selected from the group of silane compounds represented by (IV).

R ²

^{R 1 - 0 - S i (} I)

R ⁴

OR ¹

R ⁵ — 0— SR ⁷ (II)

R ¹

0-R ¹⁰

^{R 9 - 0 - S i -OR} 11

(III)

1 ²

OR ¹⁴

R ¹³ — 0— S i -OR ¹⁵ (IV)

O-R 16

(In the formula, R ′, R ⁵ , R ⁶ , R ^g , R ¹⁰ , R ", R ¹³ , R", R ¹⁵ and R ¹⁶ represent a hydrogen atom and a hydrocarbon residue having carbon number:! To 6 R ² , R ³ , R ⁴ , R ⁷ , R ⁸ and R ′ ² are each a hydrogen atom, a hydrocarbon residue having 1 to 22 carbon atoms, An atom independently selected from the group consisting of hydrocarbon residues having a functional group containing one or more atoms each independently selected from the group consisting of fluorine, oxygen, nitrogen, iodide and phosphorus; or Indicates a residue.)

2. The method for continuous production of a polyacetal resin according to claim 1, wherein the silane compound is previously added to and mixed with at least one of trioxane, cyclic ether and cyclic formal.