JP2011209306A - Method for quantitating free boric acid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for selectively quantitating free boric acid included in a polymer composition.SOLUTION: The method for quantitating free boric acid in the polymer composition including a polymer material and free boric acid includes following processes (A)-(D); a process (A) for crushing the polymer material, a process (B) for mixing the polymer composition crushed in the process (A) with a coordinating compound capable of forming the free boric acid and a complex ion, a process (C) for removing the polymer material from the mixture obtained by the process (B), and a process (D) for quantitating the boric acid included in the mixture from which the polymer material is removed in the process (C).

Description

  The present invention relates to a method for quantifying free boric acid.

  Conventionally, as a method for quantifying boric acid contained in a polymer composition, the film-like polymer composition is subjected to high-frequency inductively coupled plasma (ICP) emission spectroscopy, thereby determining the boron content in the polymer composition. A method by analyzing and converting the boron content into boric acid content has been known (Patent Document 1).

JP 2009-104062 A

  However, such a quantitative method cannot distinguish between boric acid forming a crosslinked structure with the polymer substance in the polymer composition and free boric acid contained in the polymer composition. There has been a demand for a method for selectively quantifying free boric acid contained in a polymer composition.

The present invention includes the following inventions.
[1] A method for quantifying free boric acid in a polymer composition comprising a polymer substance and free boric acid, comprising the following steps (A) to (D):
(A): Step of pulverizing the polymer composition (B): Step of mixing the polymer composition pulverized in the step (A) with a coordination compound capable of forming a complex ion with free boric acid ( C): Step of removing the polymer material from the mixture obtained in Step (B) Step (D): Step of quantifying boric acid contained in the mixture from which the polymer material has been removed in Step (C) [2] Release The method according to [1], wherein the coordination compound capable of forming a complex ion with boric acid is an alcohol compound having two or more hydroxyl groups;
[3] The method according to [2], wherein the alcohol compound having two or more hydroxyl groups is 2-ethyl-1,3-hexanediol;
[4] The method according to any one of [1] to [3], wherein the quantification in step (D) is quantification using ICP emission spectral analysis;
[5] The method according to any one of [1] to [4], wherein the polymer substance is polyvinyl alcohol;
[6] The method according to any one of [1] to [4], wherein an organic solvent that does not substantially dissolve the polymer substance is further mixed in the step (B);
[7] The method according to [5], wherein in step (B), an aromatic solvent or a halogenated hydrocarbon solvent is further mixed;
[8] The method according to [5], wherein chloroform is further mixed in the step (B);
[9] The method according to any one of [1] to [8], wherein the mixture obtained in step (B) does not substantially contain water;
[10] The method according to any one of [1] to [9], wherein the polymer composition pulverized in step (A) forms a laminate with another polymer film;
[11] The method according to any one of [1] to [10], wherein the pulverization in the step (A) is freeze pulverization.
[12] Any one of [1] to [11], wherein the 90% cumulative particle size from the fine particle side of the cumulative particle size distribution of the polymer composition pulverized in step (A) is 0.1 to 500 μm. The method described.

  According to the present invention, free boric acid contained in a polymer composition can be selectively quantified.

  Hereinafter, the present invention will be described in detail.

  First, the step (A) will be described. Step (A) is a step of pulverizing the polymer composition.

  The polymer composition (hereinafter sometimes referred to as “the present polymer composition”) usually contains a polymer substance and free boric acid, and further forms a crosslinked structure with the polymer substance. It is preferable to contain boric acid. Hereinafter, the polymer substance in the polymer composition may be referred to as “the polymer substance”, and boric acid forming a crosslinked structure with the polymer substance may be referred to as “cross-linked boric acid”. In the present invention, “free boric acid” refers to boric acid contained in the present polymer composition other than cross-linked boric acid, and usually “unreacted boric acid” that has not reacted with the polymer substance. Acid ".

  The polymer material may be a homopolymer, or may be a random copolymer or a block copolymer copolymerized with a copolymerizable monomer other than the main monomer. The functional group may be partially esterified. Among polymer substances, examples of the homopolymer include water-soluble polymers such as polyvinyl alcohol, polyphenol, and polyethylene glycol, polyolefins such as polyethylene and polypropylene, polyethylene terephthalate, and polymethyl methacrylate. Of these, water-soluble polymers are preferable, and polyvinyl alcohol is more preferable. Examples of the copolymerizable monomer include α-olefins having 2 to 30 carbon atoms such as ethylene, propylene, 1-butene and isobutene; (meth) acrylic acid or a salt thereof; methyl (meth) acrylate, (meth) Ethyl acrylate, n-propyl (meth) acrylate, i-propyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, t-butyl (meth) acrylate, ( (Meth) acrylic acid esters such as 2-ethylhexyl (meth) acrylate, dodecyl (meth) acrylate, octadecyl (meth) acrylate; (meth) acrylamide, N-methyl (meth) acrylamide, N-ethyl (meth) ) Acrylamide, N, N-dimethyl (meth) acrylamide, diacetone (meth) acrylamide, (meth) acrylic (Meth) acrylamide derivatives such as imidopropanesulfonic acid or salts thereof, (meth) acrylamidopropyldimethylamine or salts thereof, N-methylol (meth) acrylamide or derivatives thereof; N-vinylformamide, N-vinylacetamide, N-vinyl N-vinylamides such as pyrrolidone; methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, i-propyl vinyl ether, n-butyl vinyl ether, i-butyl vinyl ether, t-butyl vinyl ether, dodecyl vinyl ether, stearyl vinyl ether, polyoxyethylene vinyl ether, etc. Vinyl ether; Vinyl cyanide such as (meth) acrylonitrile; Halogenation of vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene fluoride, etc. Vinyl; vinyl carbonate such as vinyl ethyl carbonate; dihydroxybutene derivatives such as 3,4-diacetoxy-1-butene and 3,4-diethoxy-1-butene; allyl compounds such as allyl acetate and allyl chloride; maleic acid or a salt thereof Or esters; itaconic acid or salts or esters thereof; vinylsilyl compounds such as vinyltrimethoxysilane; unsaturated sulfonic acids, etc.

  The polymer composition is preferably plate-shaped. Moreover, this plate-shaped this polymer composition may form the laminated body with the other polymer film. Examples of the polymer film material that may form a laminate with the present polymer composition include cellulose resin such as triacetyl cellulose, polyester resin, polyethersulfone resin, polysulfone resin, polycarbonate resin, polyamide resin, polyimide Examples thereof include resins, polyolefin resins, (meth) acrylic resins, cyclic polyolefin resins (norbornene resins), polyarylate resins, polystyrene resins, polyvinyl alcohol resins, and mixtures thereof. These polymer films may be subjected to a treatment such as a hard coat treatment, an antireflection treatment, an antisticking treatment, a treatment for diffusion, and a treatment for antiglare. Moreover, the laminated body containing these polymer films and this polymer composition may further contain a glass substrate or an adhesive layer.

  The polymer composition may be a commercially available product or may be obtained by any known method.

  Examples of the method for pulverizing the polymer composition include freeze pulverization using a freeze pulverizer and pulverization using a ball mill, a mixer mill, a cutting mill, a mortar, and the like. Of these, freeze pulverization is preferable. The freezing temperature is preferably 0 ° C. or less, more preferably in the range of −273 ° C. to −100 ° C., and more preferably about −196 ° C. of the liquid nitrogen temperature. In order to reduce variation in the concentration of free boric acid finally obtained, it is preferable to carry out pulverization in an inert gas atmosphere. Nitrogen gas is preferably used as the inert gas. In the case of freeze pulverization, in a dry box filled with nitrogen gas, the polymer composition and pulverization balls are placed in a pulverization container, the container is sealed, and the container is taken out of the dry box and frozen and pulverized in the atmosphere. After setting in the apparatus and performing the pulverization operation, it is preferable to open the pulverization container again in a dry box filled with nitrogen gas from the viewpoint of not taking too much work space.

  In the pulverization, the above laminate can be used as it is as the polymer composition.

  The particle size of 90% cumulative from the fine particle side of the cumulative particle size distribution of the polymer composition obtained by such pulverization (hereinafter sometimes referred to as “90% D”) is preferably 0.1 to 500 μm. More preferably, it is 1-300 micrometers, More preferably, it is 10-100 micrometers. When the above laminate is used as it is as the present polymer composition, 90% D of the present polymer composition in the laminate is preferably in the range of 0.1 to 500 μm.

  The measurement of 90% D of the polymer composition can be performed using a commercially available particle size measuring apparatus.

  Next, the step (B) will be described. Step (B) is a step of mixing the polymer composition pulverized in step (A) with a coordination compound capable of forming a complex ion with free boric acid.

  Examples of the coordinating compound capable of forming a complex ion with free boric acid used in the step (B) (hereinafter sometimes referred to as “the present coordinating compound”) include, for example, 2-ethyl-1,3. -Alcohol compounds having two or more hydroxyl groups such as hexanediol, ethylene glycol, glycerin, sorbitol; methanol, salicylic acid, citric acid and the like. Among these, alcohol compounds having two or more hydroxyl groups are preferable, and 2-ethyl-1,3-hexanediol is more preferable.

  The amount of the present coordinating compound used theoretically may be 2 mol or more per 1 mol of free boric acid. When the content of free boric acid is not known, it is preferable to use the present coordinating compound in the range of 1 to 50 parts by mass with respect to 1 part by mass of the present polymer composition.

  In the step (B), it is preferable to further mix an organic solvent that does not substantially dissolve the polymer substance (hereinafter sometimes referred to as “the present organic solvent”). Here, “substantially does not dissolve the present polymer substance” means that the organic solvent only dissolves the polymer substance to such an extent that it is generally called insoluble. Is not synonymous ”is synonymous. The present coordinating compound can also be used as the organic solvent. Also, for example, when the polymer substance is polyvinyl alcohol, the organic solvent is preferably an aromatic solvent such as benzene or toluene, or a halogenated hydrocarbon solvent such as chloroform or dichloromethane, and more preferably chloroform. .

  When using this organic solvent, the usage-amount is the range of 10 mass parts-500 mass parts with respect to 1 mass part of this polymeric substance.

  A mixing method of the present polymer composition and the present coordinating compound is not particularly limited. The upper limit of the mixing temperature is the lower boiling point of the present coordinating compound and the present organic solvent. The lower limit of the mixing temperature is the lowest temperature at which the present coordinating compound can exist as a liquid in the mixture. Therefore, the range of the mixing temperature varies depending on the present coordinating compound, the present organic solvent, and the amount used thereof, but a range of 0 ° C. to 40 ° C. is preferable.

  It is preferable that the mixture obtained by the step (B) does not substantially contain water. Here, “substantially free of water” means that the water content in the mixture is usually 1% or less, preferably 0.1% or less. When the mixture does not substantially contain water, free boric acid tends to be selectively quantified.

  Next, process (C) is demonstrated. Step (C) is a step of removing the polymer substance from the mixture obtained in step (B).

  The mixture obtained in the step (B) usually comprises a solid phase containing the present polymer substance and a liquid phase containing the present coordinating compound and free boric acid. In this case, removing the present polymer substance from the mixture obtained in step (B) refers to an operation of obtaining the liquid phase by separating the solid phase and the liquid phase.

  Examples of such operations include normal solid-liquid separation operations such as filtration and decantation, and filtration is preferred. The filter used for filtration is not particularly limited as long as the particles of the polymer composition are not passed. The filtration temperature is in accordance with the mixing temperature in step (B). After obtaining the liquid phase by filtration, the solid phase on the filter may be washed with the organic solvent. The cleaning liquid obtained by such cleaning can be used in the next step (D) together with the liquid phase.

  Finally, step (D) will be described. Step (D) is a step of quantifying boric acid contained in the mixture from which the present macromolecular substance has been removed in step (C).

  As the mixture from which the present macromolecular substance has been removed in the step (C), the liquid phase may be used as it is for the step (D), or the liquid phase and the washing liquid may be mixed and used for the step (D). May be.

  Examples of the method for quantifying boric acid in the mixture include methylene blue absorptiometry, azomethine H absorptiometry, ICP emission spectrometry, ICP mass spectrometry (see JIS K 0102), neutralization titration, Curcumin-oxalic acid method (see the Analytical Chemistry Society of Japan, “New Experimental Science Course 9 Analytical Chemistry” Maruzen, Vol. 1 (1976), p. 76-80), X-ray fluorescence analysis (for example, JP-A-2007- 334307)) or the like. The method using ICP emission spectroscopy is preferable.

  Thus, all the boric acid quantified in the step (D) can be regarded as free boric acid contained in the present polymer composition. Therefore, if steps (A) to (D) are carried out, free boric acid contained in the polymer composition can be quantified.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated concretely, this invention is not these limited.

<Particle size measurement condition 1>
Device name: SALD-2000J (manufactured by Shimadzu Corporation)
Cell used: Batch cell Dispersing solvent / dispersant: Hexane + 10% sodium di-2-ethylhexyl sulfosuccinate Dispersion method: (Stirrer stirring + ultrasonic irradiation) 1 minute Refractive index: 1.70-0.20i
Measurement start time: Immediately after feeding the batch cell

<Particle size measurement condition 2>
Device name: MT-3300EX II (manufactured by Nikkiso Co., Ltd.)
Use cell: Stainless steel cell Dispersion solvent / dispersant: None (dry type)
Refractive index: 1.50
Measurement start time: Immediately after cell insertion

<Quantitative condition 1 of boric acid>
Device name: ICP emission spectrometer ICPS-8100 (manufactured by Shimadzu Corporation)
Measurement wavelength: B 249.773 nm
Standard product used for preparing calibration curve: For atomic absorption analysis: Boron standard stock solution (1000 ppm) Kanto Chemical Co., Ltd. Measurement sample: 0.6 g of filtrate was weighed out and fixed to 10 mL with ethanol.
All the obtained boron contents were regarded as being derived from boric acid, and converted to boric acid content.

<Quantitative condition 2 of boric acid>
Device name: ICP emission spectrometer SPS5520
(SII Nano Technology Co., Ltd.)
Measurement wavelength: B 249.678 nm
Standard product used to create the calibration curve: Mixed standard solution for solvent (500 ppm)
All the obtained boron contents were regarded as being derived from boric acid, and converted to boric acid content.

<Measurement sample 1>
As the measurement sample 1, a polarizer used in various liquid crystal display devices such as a television, a personal computer, and a mobile phone was used. The polarizer is produced by dyeing and uniaxially stretching a polyvinyl alcohol (PVA) film. The polarizer is stretched by immersing the film in an aqueous solution containing boric acid and subjected to water resistance treatment by crosslinking. After the water resistance treatment, water washing is performed. The structural formula of polyvinyl alcohol is represented by the following formula (I).

<Measurement sample 2>
As the measurement sample 2, a polarizer in which water washing after the water resistance treatment is weaker than the measurement sample 1 was used.

<Measurement sample 3>
As the measurement sample 3, a film made of triacetyl cellulose (KC8UX2M, manufactured by Konica Minolta Opto Co., Ltd., thickness: 80 μm) that has been previously saponified on one side of the measurement sample 2, and a corona on the other side in advance. The polarizing plate obtained by laminating | stacking the cycloolefin type-resin film (ZEONOR film, Co., Ltd. product made from OPTES Co., Ltd., thickness: 60 micrometers) which gave the process through the adhesive bond layer, respectively was used.

<Measurement sample 4>
As the measurement sample 4, a film made of triacetyl cellulose (KC8UX2M, manufactured by Konica Minolta Opto Co., Ltd., thickness: 80 μm) that has been previously saponified on one side of the measurement sample 1 is previously saponified on the other side. The polarizing plate obtained by laminating | stacking the film (KC4FR-1, the Konica Minolta Opto Co., Ltd. product, thickness: 42 micrometers) made from the triacetyl cellulose to which the chemical treatment was performed through the adhesive layer was used, respectively.

<Measurement sample 5>
As the measurement sample 5, a polarizing plate provided with an adhesive layer on one side of the measurement sample 4 was used.

Example 1
50 mg of the measurement sample 1 cut into about 1 cm square with scissors was filled into a sample container together with a steel ball. Thereafter, the measurement sample was freeze pulverized using a freeze pulverization apparatus JFC-300 (manufactured by Japan Analytical Industrial Co., Ltd.) using liquid nitrogen as a refrigerant under conditions of precooling 7 minutes and vibration 5 minutes. The pulverized measurement sample was left at room temperature for about 30 minutes. The weight of the obtained powder was 50 mg. This operation was repeated twice to obtain 100 mg of a ground measurement sample. When the particle diameter of the obtained measurement sample was determined under the above measurement condition 1, 90% D was 47.8 μm. Similarly, 10% D and 50% D were 3.36 μm and 14.0 μm, respectively (step (A ′)).
100 mg of the obtained measurement sample was mixed with 3.5 mL of a mixed solution of 2-ethyl-1,3-hexanediol / chloroform (volume ratio: 10/90) and allowed to stand at room temperature for 24 hours (above, step (A )). The resulting mixture was filtered using a 0.2 μm filter (step (B) above). The obtained filtrate was analyzed under the boric acid quantitative condition 1 (step (C) above). The boron content in the measurement sample was 0.03% by mass, and the boric acid content was 0.20% by mass.
In Example 1, it can be seen that the measurement sample was not substantially dissolved in the mixed solvent, and free boric acid could be selectively quantified.

Example 2
In Example 1, instead of the measurement sample 1 cut to about 1 cm square with scissors, the measurement sample 2 was cut to about 2 to 5 mm square with scissors, and the same procedure as in Example 1 was used. And freeze crushed. When the particle diameter of the obtained measurement sample was determined under the above measurement condition 2, 90% D was 26.0 μm. Similarly, 10% D and 50% D were 1.32 μm and 5.39 μm, respectively. Further, when the filtrate obtained in the same manner as in Example 1 was analyzed under the boric acid quantitative condition 2, the boron content in the measurement sample was 0.054% by mass, and the boric acid content was 0.37% by mass. Met.
From Examples 1 and 2, it can be seen that a larger amount of free boric acid remained in the measurement sample 2 whose water washing after the water resistance treatment was weaker than the measurement sample 1.

Example 3
In Example 1, instead of the measurement sample 1 cut to about 1 cm square with scissors, the measurement sample 3 was used in the same manner as Example 1 except that the measurement sample 3 was cut to about 2 to 5 mm square with scissors. And freeze crushed. When the particle diameter of the obtained measurement sample was determined under the above measurement condition 2, 90% D was 269 μm. Similarly, 10% D and 50% D were 22.6 μm and 206 μm, respectively. Further, when the filtrate obtained in the same manner as in Example 1 was analyzed under the boric acid quantitative condition 2, the boron content in the measurement sample was 0.009% by mass, and the boric acid content was 0.054% by mass. Met.
In Example 3, the polarizer in the measurement sample was not substantially dissolved in the mixed solvent, indicating that the free boric acid contained in the polarizer could be selectively quantified.

Example 4
In Example 1, instead of the measurement sample 1 cut to about 1 cm square with scissors, the measurement sample 4 was used in the same manner as Example 1 except that the measurement sample 4 was cut to about 2 to 5 mm square with scissors. And freeze crushed. When the particle diameter of the obtained measurement sample was determined under the above measurement condition 1, 90% D was 58.5 μm. Similarly, 10% D and 50% D were 1.32 μm and 13.2 μm, respectively. Further, when the filtrate obtained in the same manner as in Example 1 was analyzed under the boric acid quantitative condition 2, the boron content in the measurement sample was 0.007% by mass, and the boric acid content was 0.040% by mass. %Met.
In Example 4, the polarizer in the measurement sample was not substantially dissolved in the mixed solvent, indicating that the free boric acid contained in the polarizer could be selectively quantified.

Example 5
In Example 1, instead of the measurement sample 1 cut to about 1 cm square with scissors, the measurement sample 5 was cut to about 2 to 5 mm square with scissors, and the same procedure as in Example 1 was used. And freeze crushed. When the filtrate obtained in the same manner as in Example 1 was analyzed under the boric acid quantitative condition 1, the boron content in the measurement sample was 0.006% by mass and the boric acid content was 0.034% by mass. It was.
In Example 5, the polarizer in the measurement sample was not substantially dissolved in the mixed solvent, indicating that the free boric acid contained in the polarizer could be selectively quantified.

Reference example 1
35 mg of the measurement sample 1 cut into 2 mm squares with scissors is mixed with 3.5 mL of a mixed solution of 2-ethyl-1,3-hexanediol / chloroform (volume ratio: 10/90) and left at room temperature for 168 hours. did. The solution was analyzed according to boric acid quantitative condition 1 in the obtained mixture. The boron content in the measurement sample was less than 0.01% by mass (less than the lower limit of detection).
From the results of Reference Example 1, it is understood that free boron cannot be quantified unless the measurement sample is pulverized (90% D is 0.1 to 500 μm).

Reference example 2
In Reference Example 1, analysis was performed in the same manner as in Reference Example 1 except that heavy water was used instead of the 2-ethyl-1,3-hexanediol / chloroform (volume ratio: 10/90) mixed solution. The boron content was 1.5% by mass and the boric acid content was 8.7% by mass.

Reference example 3
In Reference Example 2, analysis was performed in the same manner as in Reference Example 1 except that the sample was left at 80 ° C. for 1 hour instead of being left at room temperature for 168 hours. As a result, the boron content in the measurement sample was 3.9% by mass. The acid content was 22% by mass.

  When visually confirmed in Reference Examples 2 and 3, it was observed that a part of the measurement sample was dissolved in heavy water. That is, it can be seen that the results of Reference Examples 2 and 3 were measured without distinguishing between crosslinked boric acid and free boric acid.

  According to the present invention, free boric acid contained in a polymer composition can be selectively quantified.

Claims (12)

A method for quantifying free boric acid in a polymer composition comprising a polymer substance and free boric acid, comprising the following steps (A) to (D):
(A): Step of pulverizing the polymer composition (B): Step of mixing the polymer composition pulverized in the step (A) with a coordination compound capable of forming a complex ion with free boric acid ( C): Step of removing the polymer material from the mixture obtained in Step (B) (D): Step of quantifying boric acid contained in the mixture from which the polymer material has been removed in Step (C) The method according to claim 1, wherein the coordination compound capable of forming a complex ion with free boric acid is an alcohol compound having two or more hydroxyl groups. The method according to claim 2, wherein the alcohol compound having two or more hydroxyl groups is 2-ethyl-1,3-hexanediol. The method according to any one of claims 1 to 3, wherein the quantification in the step (D) is quantification using ICP emission spectral analysis. The method according to any one of claims 1 to 4, wherein the polymer substance is polyvinyl alcohol. The method according to any one of claims 1 to 4, wherein an organic solvent that does not substantially dissolve the polymer substance is further mixed in the step (B). The method according to claim 5, wherein an aromatic solvent or a halogenated hydrocarbon solvent is further mixed in the step (B). The method according to claim 5, wherein chloroform is further mixed in the step (B). The method according to any one of claims 1 to 8, wherein the mixture obtained in step (B) is substantially free of water. The method according to any one of claims 1 to 9, wherein the polymer composition pulverized in the step (A) forms a laminate with another polymer film. The method according to any one of claims 1 to 10, wherein the pulverization in the step (A) is freeze pulverization. The method according to any one of claims 1 to 11, wherein the 90% cumulative particle size from the fine particle side of the cumulative particle size distribution of the polymer composition pulverized in step (A) is 0.1 to 500 µm.