JP2009051927A - Polyacetal resin having new crystal structure and method for controlling crystal structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyacetal resin having a new crystal structure characterized by a lamellar period structure of 20-40 nm at 25°C. <P>SOLUTION: The polyacetal resin contains a polyoxymethylene unit formed by the repetition of mainly oxymethylene unit and a polyalkylene glycol unit and has a lamellar period structure of 20-40 nm at 25°C. Preferably, the polyalkylene glycol is polyethylene glycol and its number-average molecular weight is ≥2,000. The oxymethylene unit contains 0-10 mol of 2-6C oxyalkylene units based on 100 mol of the oxymethylene unit. The ratio of the polyoxymethylene unit to the polyalkylene glycol unit (former unit/latter unit) is 99/1 to 50/50 in terms of weight percent. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a polyacetal resin having a novel crystal structure and a crystal structure control method.

  The polyacetal resin, which is a crystalline polymer, has a crystalline phase and an amorphous phase in a temperature range below the crystallization temperature, and the crystalline phase is further divided into a folded chain crystal (lamellar crystal) and an extended chain crystal.

And it is known that the space | interval of a lamellar crystal phase exists in 14-20 nm at room temperature (nonpatent literature 1), and when it crystallizes at high temperature, it is known that a lamellar period will expand ( Non-patent document 2).
Polymer 44 (2003) 2159-2168 Polymer 44 (2003) 6973-6988

  However, a polyacetal resin having a lamellar period of 20 nm or more in a temperature range in which a polyacetal resin is usually used, for example, a temperature range of 20 to 100 ° C. has not been known so far.

  The polyacetal resin having such a crystalline higher-order structure is expected to improve mechanical properties and gas permeability as compared with the conventional polyacetal resin. Development of the control method and new crystals obtained thereby There has been a need for polyacetal resins having a structure.

  As a result of intensive studies to meet such demands, the present inventors have found an effective method for controlling the lamellar period of the polyacetal resin, and a polyacetal resin having a novel crystal structure achieved thereby, and have found the present invention. Reached.

  That is, the present invention relates to a polyacetal resin comprising a polyoxymethylene unit and a polyalkylene glycol unit mainly formed by repeating oxymethylene units, and having a lamellar periodic structure of 20 to 40 nm at 25 ° C. And a method for controlling a lamellar period of a polyacetal resin.

  According to the present invention, it was confirmed that an unprecedented polyacetal resin having a lamellar periodic structure of 20 to 40 nm can be obtained. It was also found that the lamellar period can be controlled by the molecular weight of polyethylene glycol used for polymerization. Thus, the polyacetal resin having a controlled crystal higher-order structure improves flexibility and gas permeability, and is expected to develop into new applications.

  Hereinafter, the present invention will be described in detail.

  As described above, the polyacetal resin of the present invention has a polyoxymethylene unit mainly formed by repeating oxymethylene units and a polyalkylene glycol unit, and has a lamellar periodic structure of 20 to 40 nm at 25 ° C. It is characterized by. This lamellar periodic structure increases somewhat with increasing temperature, but the degree is slight, and in the temperature range of about 20-100 ° C where polyacetal resin is usually used, the lamellar periodic structure of 20-45 nm Will be retained. Such a specific lamellar periodic structure is achieved by adding or introducing a polyalkylene glycol unit in a block copolymerization manner to one or both ends of a polymer skeleton composed of polyoxymethylene units. .

  Here, the polyoxymethylene unit that forms the polyacetal resin of the present invention includes formaldehyde, repeating units of oxymethylene units formed by homopolymerization such as trioxane and tetraoxane, which are cyclic oligomers thereof, and oxymethylene. What has a small amount of other structural units besides the unit is included.

  As a structural unit other than the oxymethylene unit, an oxyalkylene unit having 2 to 6 carbon atoms is preferable, and the ratio thereof is preferably 0 to 10 mol, particularly preferably 0.1 to 5 mol, per 100 mol of the oxymethylene unit. Such oxyalkylene units can be introduced by using, for example, ethylene oxide, 1,3-dioxolane, diethylene glycol formal, 1,4-butanediol formal and the like as a copolymerization component.

  In the present invention, examples of the compound for forming a polyalkylene glycol unit include polyethylene glycol and polypropylene glycol. Polyethylene glycol is preferable. The polyalkylene glycol preferably has a number average molecular weight of 2000 or more, whereby the desired lamellar periodic structure can be controlled more appropriately.

  In the present invention, the ratio of the polyoxymethylene unit and the polyalkylene glycol unit as described above constituting the polyacetal resin is preferably the former / the latter = 99-50 / 1-50 (% by weight), particularly preferably the former / the latter = It is 90-60 / 10-40 (weight%).

  When the proportion of polyoxymethylene units is excessive, the desired specific lamellar periodic structure cannot be obtained. Conversely, when the proportion of polyoxymethylene units decreases, the properties inherent to polyacetal resin are impaired. .

  Next, the control method of the lamellar period of the polyacetal resin in this invention is demonstrated.

  The control of the lamellar period of the polyacetal resin in the present invention is basically performed by adding or introducing a polyalkylene glycol unit in a block copolymerization manner at one or both ends of a polymer skeleton composed of polyoxymethylene units. This is done by adopting a structured.

  Therefore, the lamella cycle can also be controlled by a method in which a polymer composed of polyoxymethylene units is once prepared and a polyalkylene glycol unit is added to one or both ends by block copolymerization or graft copolymerization. However, it is more preferable to control the lamella cycle by the method described below.

  That is, in the presence of polyalkylene glycol, polymerization of 0 to 30 moles of a compound selected from 100 moles of trioxane and cyclic ether and cyclic formal is carried out, and polyoxymethylene units and polyalkylenes formed mainly by repeating oxymethylene units. This is a method for controlling the lamellar period of a polyacetal resin by using a block copolymer having a glycol unit. Thereby, it becomes possible to control the polyacetal resin to have a lamellar periodic structure of 20 to 40 nm at 25 ° C.

  As the cyclic ether or cyclic formal, ethylene oxide, 1,3-dioxolane, diethylene glycol formal, 1,4-butanediol formal and the like can be used, and as the polyalkylene glycol, polyethylene glycol, polypropylene glycol and the like can be used. In order to more appropriately control the lamellar periodic structure, the polyalkylene glycol used preferably has a number average molecular weight of 2000 or more. In the above reaction, the ratio of the total amount of the compound selected from trioxane, cyclic ether and cyclic formal and the polyalkylene glycol to be present is the former / the latter = 99-50 / 1-50 (% by weight). Is preferred.

  In the method for controlling the lamellar period of the polyacetal resin as described above, the polymerization method is not particularly limited, and examples thereof include bulk polymerization. The bulk polymerization may be either batch type or continuous type.

  More specifically, polyalkylene glycol may be dissolved in a compound selected from trioxane and optionally used cyclic ether and cyclic formal, and polymerization may be performed by adding a catalyst thereto. The polymerization temperature is preferably maintained at 60 to 120 ° C. As the polymerization catalyst, any compound conventionally known as a catalyst for producing polyacetal resin can be used. For example, boron trifluoride, tin tetrachloride, titanium tetrachloride, phosphorus pentafluoride, phosphorus pentachloride, pentafluoride, Antimony chloride, heteropolyacid, perfluoroalkylsulfonic acid, and complex compounds and salts thereof.

The amount of the polymerization catalyst varies depending on the degree of catalytic ^{activity, 1 × 10 -6 ~1 × 10-} 2 mol is preferred to 1 mol of the total amount of trioxane and cyclic ether and / or cyclic formal, 5 More preferably, × 10 ⁻⁶ to 1 × 10 ⁻⁴ mol. The obtained polymer is subjected to deactivation of the polymerization catalyst, terminal stabilization and addition of a stabilizer according to a conventional method as necessary.

  The lamellar periodic structure of the polyacetal resin in the present invention prepared as described above is observed by small angle X-ray scattering measurement. For example, RINT 2500 manufactured by Rigaku Corporation is used, and the lamella interval d is calculated from the scattering vector q of the obtained scattering peak. The scattering vector q is defined by the following formula (1), and the lamella interval d is given by the formula (2).

q = (4πsinθ) / λ (1)
Here, θ is the scattering angle, and λ is the X-ray wavelength used for the small-angle X-ray scattering measurement.

  d = 2π / q (2)

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

Example 1
40 parts by weight of polyethylene glycol having a number average molecular weight of 3000 is dissolved in 60 parts by weight of trioxane at 80 ° C., and boron trifluoride dibutyl ether complex is added at a molar ratio of 5.1 × 10 ⁻³ to trioxane, and at 80 ° C. for 35 minutes. A polymerization reaction was performed. 5 g of the obtained polymer was dissolved in 10 ml of dimethylformamide (DMF) at 150 ° C., and 10 μl of diazabicycloundecene (DBU) was added to decompose and remove the alkali labile component.
When the obtained polymer was dissolved in hexafluoroisopropanol-d2 and subjected to 1H NMR measurement, it was a block copolymer having 37.6% by weight of polyethylene glycol units in the total polymer composition, and its number average molecular weight was 28400. It was confirmed that.
Next, small angle X-ray scattering measurement of this polymer was performed under a temperature condition of 25 ° C. As shown in FIG. 1, strong scattering was observed at the positions of q = 0.3 and 0.42, and it was shown that the scattering has a lamellar periodic structure of 20.9 nm and 15.0 nm, respectively.

Example 2
Example 1 except that the polyethylene glycol in Example 1 is changed to one having a number average molecular weight of 6000, the boron trifluoride dibutyl ether complex is 2.8 × 10 ^{−3 in} molar ratio to trioxane, and the polymerization time is 7 minutes. Polymerization was carried out in the same manner as above, and the alkali-labile components of the resulting polymer were decomposed and removed. The obtained polymer was a block copolymer having 36.5% by weight of polyethylene glycol units in the total polymer composition, and the number average molecular weight was confirmed to be 24,500. In addition, strong scattering was observed at the positions of q = 0.27 and 0.43 by small-angle X-ray scattering, indicating that they have lamellar periodic structures of 23.3 nm and 14.6 nm, respectively.

Example 3
Example 1 except that the polyethylene glycol in Example 1 was changed to a number average molecular weight of 10,000, the boron trifluoride dibutyl ether complex was 1.9 × 10 ⁻³ in terms of molar ratio to trioxane, and the polymerization time was 45 minutes. Polymerization was carried out in the same manner as above, and the alkali-labile components of the resulting polymer were decomposed and removed. The obtained polymer was a block copolymer having 36.9% by weight of polyethylene glycol units in the total polymer composition, and the number average molecular weight was confirmed to be 48100. In addition, strong scattering was observed at the positions of q = 0.2 and 0.27 by small-angle X-ray scattering, indicating that they have lamellar periodic structures of 31.4 nm and 23.3 nm, respectively.

Comparative Example 1
Small angle X-ray scattering measurement was performed using a commercially available polyacetal resin (Duracon (registered trademark) M450-44 manufactured by Polyplastics Co., Ltd.). Scattering only showed strong scattering at the position of q = 0.38, and the lamellar period was 16.5 nm.

Comparative Example 2
60 parts by weight of a commercially available polyacetal resin (Duracon (registered trademark) M450-44 manufactured by Polyplastics Co., Ltd.) and 40 parts by weight of polyethylene glycol having a number average molecular weight of 6000 were dissolved in hexafluoroisopropanol, and then the solvent was removed. Then, a mixture of polyoxymethylene and polyethylene glycol was prepared, and small-angle X-ray scattering measurement was performed. Scattering only showed strong scattering at the position of q = 0.39, and the lamellar period was 16.1 nm.

(analysis)
The number average molecular weight of the polyethylene glycol used for polymerization in Examples 1 to 3 and the lamellar spacing of the resulting polyacetal resin were found to be correlated as shown in FIG. We have found for the first time that the cycle is controllable. This is considered that the lamellar period of the polyacetal resin is expanded by polyethylene glycol.

The small angle X-ray scattering intensity of the polymer obtained in Example 1 is shown. The vertical axis represents the scattering intensity, and the horizontal axis represents the scattering vector q. The relationship between the lamella period of the polymer obtained in Examples 1-3 and the number average molecular weight of the polyethyleneglycol used for superposition | polymerization is shown.

Claims (8)

  A polyacetal resin comprising a polyoxymethylene unit and a polyalkylene glycol unit mainly formed by repeating oxymethylene units and having a lamellar periodic structure of 20 to 40 nm at 25 ° C.   The polyacetal resin according to claim 1, wherein the polyalkylene glycol is polyethylene glycol.   The polyacetal resin according to claim 1 or 2, wherein the number average molecular weight of the polyalkylene glycol is 2000 or more.   The polyacetal resin according to any one of claims 1 to 3, wherein the polyoxymethylene unit has an oxyalkylene unit having 2 to 6 carbon atoms in a proportion of 0 to 10 mol with respect to 100 mol of the oxymethylene unit.   The polyacetal resin according to any one of claims 1 to 4, comprising a polyoxymethylene unit and a polyalkylene glycol unit at a ratio of the former / the latter = 99 to 50/1 to 50 (wt%).   In the presence of polyalkylene glycol, 100 mol of trioxane and 0 to 30 mol of a compound selected from cyclic ether and cyclic formal are polymerized, and a polyoxymethylene unit and a polyalkylene glycol unit mainly formed by repeating oxymethylene units, A method for controlling a lamellar period of a polyacetal resin, which is controlled to have a lamellar periodic structure of 20 to 40 nm at 25 ° C.   The method for controlling a lamellar period of a polyacetal resin according to claim 6, wherein the polyalkylene glycol is polyethylene glycol.   The method for controlling a lamellar period of a polyacetal resin according to claim 6 or 7, wherein the number average molecular weight of the polyalkylene glycol is 2000 or more.

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