WO2004096881A1

WO2004096881A1 - Resin material for formed article having profile cross section

Info

Publication number: WO2004096881A1
Application number: PCT/JP2004/006327
Authority: WO
Inventors: Hidetoshi Okawa; Daisaku Ikeda
Original assignee: Polyplastics Co., Ltd.
Priority date: 2003-05-01
Filing date: 2004-04-30
Publication date: 2004-11-11
Also published as: CN100371363C; CN1784441A; JPWO2004096881A1

Abstract

A resin material which comprises a polyoxymethylene copolymer having a polymer chain consisting mainly of an oxymethylene recurring unit and containing a specific oxyalkylene unit in an amount of 1.5 to 10 mol per 100 mol of the oxymethylene unit, and having a melt index (190°C, a load of 2160g) of 0.3 to 20g/10 min, and is suitable for the production of a formed article having a profile cross section. The resin material allows the production of a formed article which comprises a polyoxymethylene resin and has a profile cross section, and further is reduced in strain and excellent in dimensional accuracy.

Description

Description Resin material for molded articles having irregular cross-section

The present invention relates to a resin material which is made of a specific polyoxymethylene copolymer and has excellent mechanical properties and is suitable for producing a molded article having a good irregular cross-sectional shape, and a molded article thereof. Conventional technologies and their issues

A profile extrusion molding method is known as a technique for molding a resin material into a long body having a complicated cross-sectional shape. Such a profile extrusion molding method is performed, for example, as follows. That is, the resin material is heated, melted and kneaded by an extruder and extruded through a die for profile extrusion provided at the extruder outlet. It is cooled and solidified while shaping into a shape to obtain the desired extruded molded product. At this time, by appropriately changing the shape or sizing means of the profile extrusion die or sizing die, it is possible to obtain profile extrusion products having various cross-sectional shapes.

In the past, most of such shaped extrusions were made of polyvinyl chloride.However, since polyvinyl chloride contains chlorine as a component, it has problems such as the generation of harmful gases during incineration. The mainstream is extruded molded products made of polyolefin resins such as polypropylene and polyethylene, which are resin materials that do not contain chlorine. And since these resins are inexpensive, their extruded products are widely used in many applications including building materials.

However, because polyolefin resin has low crystallinity, the strength of the molded product is low. Has limitations, and in some cases it has not been possible to adequately respond to the recent demand for higher-strength profiled extrusions.

In contrast, a polyoxymethylene resin having a polymer skeleton composed mainly of repeating oxymethylene units is known to have high crystallinity and to be excellent in rigidity, strength, chemical resistance, solvent resistance, and the like. Because of its high crystallization speed and fast molding cycle, it is widely used as an injection molding material in the field of mechanical parts for automobiles and electrical equipment.

As described above, polyoxymethylene resin has excellent properties, but polyoxymethylene resin has high crystallinity, high crystallization speed, and large molding shrinkage. When used in such a method, drawdown occurs or distortion occurs due to shrinkage during cooling and solidification, and the product is deformed, and it is extremely difficult to form a desired cross-sectional shape.

For this reason, profile extrusion molding using a polyoxymethylene resin has hardly been performed in the past, and such behavior in the profile extrusion molding of a polyoxymethylene resin is based on the polyoxymethylene resin described above. Due to such essential properties as described above, it was considered difficult to improve it to one suitable for profile extrusion, and it has hardly been studied.

As one of the few prior arts relating to such profile extrusion molding of a polyoxymethylene resin, a hollow extruded product for a pen tip having an ink flow path is known (for example, Japanese Patent Application Laid-Open No. 59-22749). No. 8 and Japanese Patent Application Laid-Open No. H08-142465). The techniques disclosed in these documents are characterized by the selection of materials in consideration of the performance of the pen tip, and are particularly useful for profile extrusion, especially for profiles with complex cross-sections and for profiles with large cross-sections. No disclosure is made of a polyoxymethylene resin material that can be particularly effectively applied to the above. Disclosure of the invention

An object of the present invention is to solve the above problems and provide a resin material comprising a polyoxymethylene copolymer capable of efficiently producing a deformed cross-section molded article having small distortion and excellent dimensional accuracy. It is in.

The present inventors have conducted intensive studies in order to achieve the above object, and as a result, using a resin material made of a specific polyoxymethylene copolymer having a controlled crystallization rate, improved the profile extrusion processability, The present inventors have found that an excellent molded product with little distortion can be obtained, and have reached the present invention.

That is, the present invention comprises, in a polymer chain mainly composed of repeating oxymethylene units, 1.5 to 10 mol of oxyalkylene units represented by the following general formula (1) per 100 mol of oxymethylene units, and a melt index (190 ° C.) It is a resin material composed of a polyoxymethylene copolymer having a load of 2160 g) of 0.3 to 20 g / 10 minutes and suitable for producing molded articles having an irregular cross section. Two

4 (c) _m -o

^Rl (1)

(Wherein, R ₂ is hydrogen, an alkyl group having 1 to 8 carbon atoms, selected from an organic group having an organic group, phenyl group, phenylene Le radicals having alkyl Le group having 1 to 8 carbon atoms, R ₂ May be the same or different, and m represents an integer of 2 to 6.)

Further, it is a molded article having an irregular cross section obtained from such a resin material.

The present invention also provides an application for producing a molded article having an irregular cross section of the above resin material and a method for producing a molded article having an irregular cross section including molding the above resin material. Detailed description of the invention

Hereinafter, the present invention will be described in detail.

The resin material of the present invention comprises a polyoxymethylene unit containing 1.5 to 10 mol of oxyalkylene units represented by the above general formula (1) per 100 mol of oxymethylene units in one chain of a polymer mainly composed of repeating oxymethylene units. It consists of a polymer.

In the polyoxymethylene copolymer used in the present invention, the ratio of the oxyalkylene unit represented by the general formula (1) must be 1.5 to 10 mol per 100 mol of the oxymethylene unit, and is preferably oxymethylene. It is preferably 2 to 8 mol per 100 mol of unit, particularly preferably 2 to 5 mol per 100 mol of oxymethylene unit. When the proportion of the oxyalkylene unit represented by the general formula (1) is reduced, the crystallization rate of the polyoxymethylene copolymer is increased, and when extruding a molded article having an irregular cross section, a die of an extruder is used. The molten resin extruded through is shaped into a desired cross-sectional shape by a sizing die and solidified before being cooled, so that a desired shape cannot be obtained. Also, due to the high solidification rate, the strain in the molded product generated during the solidification process becomes large, so that a deformed shape may be formed. Conversely, when the proportion of the oxyalkylene unit represented by the general formula (1) is increased, the crystallinity of the polyoxymethylene copolymer decreases, and the molded article made of such a copolymer has a high strength and elastic modulus. Etc. are low.

The polyoxymethylene copolymer used in the present invention has a melt index (Ml) of 0.3 to 20 g // 10 measured at 190 ° C under a load of 2160 g according to ASTM D-1238. Min., Preferably 0.5 to 10 g / 10 min, particularly preferably 0.5 to 5 g / 10 min. If the melt index (M l) is too small, the load during the melt extrusion process will increase, making extrusion difficult. Conversely, if the melt index (M l) becomes too large, the resin will be cut down due to the resin opening. It becomes unstable. The method for producing the above-mentioned polyoxymethylene copolymer used in the present invention is not particularly limited. It can be obtained by a method of performing bulk polymerization using a catalyst. As the polymerization apparatus, any of known apparatuses such as a batch type and a continuous type can be used. Here, the introduction ratio of the oxyalkylene unit represented by the general formula (1) is adjusted by the amount of the comonomer to be copolymerized. In addition, the melt index (Ml) can be adjusted by the amount of a chain transfer agent used during polymerization, for example, methylal or the like.

The melt index of the obtained copolymer decreases as the amount of the chain transfer agent added decreases, and increases as the amount increases. The melt index is affected by impurities such as water and methanol contained in the raw material monomer and comonomer, and the type, shape, size, and polymerization conditions of the polymerization machine. It is difficult to unambiguously determine the absolute amount of chain transfer agent required to obtain the copolymer, and the chain transfer is performed so that the desired melt index is obtained while trying to produce the copolymer. Increase or decrease the amount of agent added.

Examples of the cyclic ether compound or cyclic formal compound used as a comonomer include ethylene oxide, propylene oxide, butylene oxide, styrene oxide, oxetane, tetrahydrofuran, trioxepane, 1,3-dioxolan, propylene glycol formal, diethylene glycol formal, Examples include triethylene glycol formal, 1,4-butanediol formal, 1,5-pentanediol formal, 1,6-hexanediol formal, among which ethylene oxide, 1,3-dioxolan, diethylene glycol formal, 1,4-butanediol formal is preferred. The polyoxymethylene copolymer used in the present invention may have a branched or crosslinked structure. For this purpose, a small amount of a monofunctional or bifunctional or higher glycidyl compound other than those described above is added and copolymerized. It may be polymerized.

The polyoxymethylene copolymer obtained by polymerization is subjected to catalyst deactivation treatment, removal of unreacted monomers, washing and drying of the polymer, stabilization of unstable terminal portions, etc., followed by various stabilizers And then put to practical use by performing stabilization treatment and the like by blending the same. Representative stabilizers include hindered phenol compounds, nitrogen-containing compounds, hydroxides of alkali or alkaline earth metals, inorganic acid salts, carboxylate salts, and the like.

The polyoxymethylene copolymer thus obtained and used in the present invention preferably has an amount of hemiformal terminal groups detected by Ή-NMR of 0 to 4 mmol / kg, particularly preferably 0 to 2 imol. / kg. If the amount of the hemiformal terminal group exceeds 4 ol / kg, problems such as foaming due to decomposition of the polymer may occur during melt processing. In order to control the hemiformal terminal group within the above range, it is preferable that impurities, particularly water, in the total amount of monomers and comonomer to be subjected to the polymerization be 20 ppm or less, particularly preferably 10 ppm or less.

In the resin material used in the present invention, such a polyoxymethylene copolymer may contain, as necessary, general additives for thermoplastic resins, for example, coloring agents such as dyes and pigments, lubricants, nucleating agents, One or more types of release agents, antistatic agents, surfactants, or organic polymer materials, inorganic or organic fibrous, platy, or granular fillers are used for the purpose of the present invention. It can be added within a range that does not inhibit. '

Next, a method for producing a molded article having an irregular cross section using the resin material made of the polyoxymethylene copolymer as described above will be described. In order to produce a molded article having an irregular cross section, an irregular extrusion method is usually used. The manufacture of a molded article having an irregular cross section is basically performed as follows. That is, after the resin is heated and melted in an extruder having a single-screw or twin-screw, the molten resin is extruded from an extrusion die (die) having a predetermined shape and shaped into a target shape in a sizing process. Both are solidified by a cooling process, taken up, and cut to a desired length as necessary to obtain a long molded body. Here, straight dies, crosshead dies, flat dies, special dies, and the like are known as dies for extrusion molding, and are selected according to the purpose. The shape of the extrusion die (cross-sectional shape of the molten resin to be extruded) can be any shape design other than the round shape, and can be similar to the cross-sectional shape of the final product. Different cross-sectional shapes can be used.

In addition, a sizing process is performed in a sizing step to shape the molten resin extruded from the extrusion die into a desired shape. External sizing and internal sizing are known as sizing methods, but the external sizing method is the mainstream, and the vacuum sizing method is often used. The resin whose shape has been adjusted by sizing is cooled and solidified by a water tank, a water shower, air cooling, etc., to obtain a desired product. Cooling can be performed simultaneously with sizing, and prior to sizing, pre-cooling can be performed to the extent that the molten resin does not solidify.

The cross-sectional shape of the resulting molded article having an irregular cross-section includes open shapes such as L-shape, U-shape, E-shape, and T-shape, hollow shapes such as cylinders and square tubes, and ribs in hollow shapes. Either the provided shape with hollow ribs or a composite shape obtained by mixing these shapes is possible. Although a general method for molding a molded article having an irregular cross section has been described here, the method for producing a molded article having an irregular cross section using the resin material of the present invention is limited to the method described here. It is not done.

The molded article having an irregular cross section obtained by using the resin material comprising the polyoxymethylene copolymer of the present invention has high strength, high elastic modulus, solvent resistance, heat resistance, flex fatigue resistance and the like. There are various applications utilizing the excellent characteristics. Since the processed product is in a continuous form, it can be used by appropriately cutting it according to the purpose. For example, it can be used for rails, pipes, various building materials, and various other uses. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a sectional view showing the shape of a die used in the example. FIG. 2 is a diagram showing the shape of the vacuum sizing used in the example, (a) is a sectional view, and (b) is a side view. Example

Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited thereto.

Examples 1 to 8

A paddle was attached using a continuous mixing reactor consisting of a barrel that has a jacket through which a heat (cool) medium passes and a cross section of two circles partially overlapping, and a rotary shaft with paddles. While rotating the rotating shafts at 150 rpm, add liquid trioxane, cyclic ether or cyclic formal as a comonomer, further add methylal as a molecular weight regulator, and 50 ppm of boron trifluoride as a catalyst (based on all monomers). Was continuously supplied to a polymerization machine to perform bulk polymerization. Table showing the water content of trioxane used, the type of comonomer, and the amount of methylal (ratio to total monomer weight)

Shown in 1. The water content of each comonomer was less than 10 ppm. The target value of the melt index of the obtained copolymer was 2.0 in Examples 1 to 3 and 5 to 7, 1.5 in Example 4, and 9.0 in Example 8, and the amount of methylal was added. Fine adjustment was made within the range shown in Table 1.

The reaction product discharged from the polymerization machine was immediately passed through a crusher, and was added to a 60 ° C aqueous solution containing 0.05% by weight of triethylamine to deactivate the catalyst. Further, after separation, washing and drying, a crude polyoxymethylene copolymer was obtained. Table 2 shows the properties of the obtained copolymer.

Then, triethyl was added to 100 parts by weight of the crude polyoxymethylene copolymer. 4 parts by weight of a 5% by weight aqueous solution of amine, and 0.3 parts by weight of pentaerythristyl-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] are added, and a twin screw extruder is added. At 210 ° C. to remove unstable parts.

To 100 parts by weight of the polyoxymethylene resin obtained by the above-mentioned method, 0.03 of pentaethylene erythrityl-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] was added as a stabilizer. Parts by weight and 0.15 parts by weight of melamine were added and melt-kneaded at 210 ° C. using a twin-screw extruder to obtain a pellet-shaped resin material.

Using the pelletized resin material obtained above, the resin is melt-plasticized by an extruder at a cylinder-set temperature of 200 ° C. A die with the cross-sectional shape shown in Fig. 1 (The unit of the number in the figure is mm The resin is passed through the vacuum sizing dies (the unit of the number in the figure is mm) as shown in Fig. 2 while cooling and cooling to form a "U-shaped" rail shape. I got something. Table 2 shows the results evaluated by the evaluation method described below.

Comparative Examples 1 to 5

Polyoxymethylene (co) polymers not specified in the present invention as shown in Table 2 were prepared in the same manner as in Examples except that the amount of comonomer used or the amount of methylal as shown in Table 1 was changed. The target value of the melt index was 2.0 in Comparative Examples 1-3 and 27.0 in Comparative Example 4, and the amount of methylal added was finely adjusted within the range shown in Table 1. In Comparative Example 5, addition of methylal was not performed in order to obtain a copolymer having a small melt index.

The obtained (co) polymer was subjected to a stabilization treatment and the like in the same manner as in the examples, and was further subjected to profile extrusion to obtain a molded product. Table 2 shows the results of evaluation using the evaluation method described below.

Example 9

Polymerization was carried out in the same manner as in Example 1 except that n-butyldaricidyl ether was added as a copolymerization component together with 1,3-dioxolane, and the branched structure was as shown in Table 3. To obtain a crude polyoxymethylene copolymer. Further, after performing the same processing as in Example 1, a molded product having an irregular cross section was manufactured to obtain a "U-shaped" rail-shaped molded product. Table 3 shows the results evaluated by the evaluation method described later.

The evaluation criteria and the like in Examples and Comparative Examples are as follows.

[Melt index (Ml) measurement]

According to ASTM D-1238, it was measured at 190 ° C under a load of 2160 g.

[Polymer composition analysis]

The polymer used for evaluation of physical properties was dissolved in hexafluoroisopropanol d2, and 'Η-NMR measurement was performed. It was quantified from the peak area corresponding to each unit. In the table, the damage ij of the copolymer unit is shown in terms of mol ratio per lOOmol of oxymethylene unit.

[Terminal group analysis]

The polymer used for the evaluation of physical properties was dissolved in hexafluoroisopropanol d2, and-NMR measurement was performed. It was quantified from the peak area corresponding to each end.

[Shape determination]

It was visually observed whether or not it had a desired shape, and judged based on the following criteria. 3 points ... A desired cross-sectional shape is obtained.

2 points ... Although the desired cross section is almost obtained, slight distortion / twisting or unevenness on the surface is observed.

1 point ... The desired cross-sectional shape cannot be obtained and processing is impossible.

[Moldability]

It was determined whether there was any problem in the molding process. Copolymerization component Methylal amount Monomer (water content (ppm)) Comonomer (ppm) Example 1 TOX (13) DO 300-500 Example 2 TOX (15) DO 300-500 Example 3 TOX (15) DO 300- 500 Example 4.TOX (13) DO 300-500 Example 5 TOX (110) DO 300-500 Example 6 TOX (14) BDF 300-500 Example 7 TOX (13) EGF

Example 8 TOX (16) DO 500 to 800 Comparative Example 1 TOX (13) DO 300 to 500 Comparative Example 2 TOX (13) DO 300--500 Comparative Example 3 TOX (14) ― + 300 to 500 Comparative Example 4 TOX ( 14) DO 1000-Lake 0 Comparative Example 5 TOX (13) DO 0

TOX: .Trioxane

DO: 1, 3—dioxolan

BDF: 1,4-butanediol forma '

EGF: ethylene glycol formal

Table 2 Evaluation of polymer integrity analysis

Ml Hemiformer Sole Shape

Copolymer unit mol Formability

(g / 10min) (mmol / ka) Judgment

Example 1 (CH ₂ CH ₂ 0) 2.2 1.9 0.2 3 good

Example 2 (CH ₂ CH ₂ 0) 4.3 2.0 0.2 3 good

Example 3 (CH ₂ CH ₂ 0) 5.7 2.0 0.2 3 good

Example (CH ₂ CH ₂ 0) 2.2 1.5 0.2 3 Good

Example 5 (CH ₂ CH ₂ 0) 2.2 2.0 52 Gas generation, slight foaming Example 6 (CH ₂ CH ₂ CH ₂ CH ₂ 0) 2.2 2.1 0.2 3 Good

Example 7 (CH ₂ CH0 ₂ CH ₂ CH ₂ 0) 2.2 2.1 0.2 3 Good

Example 8 (CH ₂ CH ₂ 0) 2.2 9 0.2 2

Processing possible

Comparative Example 1 (CH ₂ CH ₂ 0) 1.2 2.2 0.2 1 Difficult to machine

Comparative Example 2 (CH ₂ CH ₂ 0) 0.48 2 0.2 1 Difficult to process

Comparative Example 3 ― ― 2 0.2 1 Difficult to process

Comparative Example 4 (CH ₂ CH ₂ 0) 2.2 27 0.2 1 • Difficult to process due to low resin viscosity Comparative Example 5 (CH ₂ CH ₂₀ ) 2.2 0.2 0.2 1 Extruder negative due to resin viscosity

Table 3 Judgment and processing of molded products

Copolymer unit-1 Shape

mol Copolymer Ut -2 mol Hemiformal

Moldability (mmol / kg) Judgment

Example 9 (CH ₂ CH ₂₀ ) 2.3 (CH (CH ₂ OC ₄ H ₉ ) CH ₂₀ ) 0.25 1.9 0.2 3 Good

3—

Claims

The scope of the claims

1. A polymer chain consisting mainly of repeating oxymethylene units contains 1.5 to 10 mol of oxyalkylene units represented by the following general formula (1) per lOOmol of oxymethylene units, and has a melt index (190, load 2160g) A resin material comprising a polyoxymethylene copolymer having a thickness of 0.3 to 20 gZ10 minutes and suitable for producing a molded article having an irregular cross section.

R ₂

~ + (C) _m -0 to

^R (1)

(Wherein, R, and R ₂ are selected from hydrogen, an alkyl group having 1 to 8 carbon atoms, an organic group having an alkyl group having 1 to 8 carbon atoms, a phenyl group, and an organic group having a phenyl group. , RR ₂ may be the same or different, and m represents an integer of 2 to 6.)

2. The resin material according to claim 1, wherein the polyoxymethylene copolymer contains 2 to 8 mol of the oxyalkylene unit per 100 mol of oxymethylene unit.

3. The resin material according to claim 1, wherein the polyoxymethylene copolymer contains 2 to 5 mol of the oxyalkylene unit per 100 mol of oxymethylene unit.

4. The resin material according to claim 1, wherein the polyoxymethylene copolymer has a melt index of 0.5 to 10 gZlO.

5. The resin material according to any one of claims 1 to 3, wherein the polyoxymethylene copolymer has a melt index of 0.5 to 5 g / 10 minutes.

6. The polyoxymethylene copolymer has a branched or cross-linked structure. The resin material according to any one of claims 1 to 5.

7. The resin material according to any one of claims 1 to 6, wherein the polyoxymethylene copolymer has a hemiformal terminal group of 0 to 4 imol / kg.

8. A molded article having an irregular cross section obtained from the resin material according to any one of claims 1 to 7.

9. Use of the resin material according to any one of claims 1 to 7 for producing a molded article having an irregular cross section.

10. A method for producing a molded article having an irregular cross-section, comprising molding the resin material according to any one of claims 1 to 7.