JP2005091121A - Method and instrument for measuring minute amount of formaldehyde released from resin - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a measuring method capable of measuring easily with satisfactory reproducibility a very minute amount of formaldehyde released from a resin material using formaldehyde or a derivative thereof as a raw material, or released from a molding thereof. <P>SOLUTION: This method is provided with an inert gas supply means A, a sealed container B provided with an inert gas introducing tube and an exhaust pipe, a heating means C for heating the sealed container B to a prescribed temperature, and an introducing tube for gas discharged from the sealed container B. The resin material or the molding of a prescribed amount to be evaluated is set in an inside of the sealed container B, using a device comprising a container D with water or an organic solvent held in its inside, the sealed container B is heated by the heating means C, the formaldehyde generated from the resin material or the molding is thereby discharged from the exhaust pipe together with the inert gas introduced from the inert gas introducing tube, so as to be guided to the container D through an introducing tube of the container D, and the gas therein is introduced into the water or the organic solvent held in the inside of the container D to absorb the formaldehyde, and the formaldehyde in an absorbent liquid is measured thereafter. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a measurement method and a measurement apparatus for trace amount of formaldehyde released from a resin, and is particularly suitably used for measurement of formaldehyde released from polyacetal resin or the like mainly using formaldehyde or a cyclic oligomer thereof. It is.

  Polyacetal resins, melamine resins, urea resins, phenol resins, and the like that use formaldehyde or a cyclic oligomer thereof as one of raw materials are used in a wide range of fields by taking advantage of the characteristics of each resin.

  However, since these resins use formaldehyde or a cyclic oligomer thereof (for example, trioxane) as one of the raw materials, a trace amount of free formaldehyde remains in the produced resin or a molded product obtained by molding the resin. When a resin or its molded product is left in a harsh usage environment for a long time, a slight amount of formaldehyde is generated due to slight decomposition of the resin. It is inevitable that the product is gradually released from the product. On the other hand, various improvements have been made in the past, but recently there has been a severe demand for reducing formaldehyde generated from resin materials and resin molded products.

As a resin material that can meet such demands, for example, Patent Document 1 proposes a polyacetal coloring material with less formaldehyde emission by using a specific initiator. In order to develop such resins and evaluate their molded products, the measurement method of formaldehyde generated from resin materials and resin molded products is important, but in reality formaldehyde generated from resin materials and resin molded products is important. Was extremely small, and there was no simple and appropriate measurement method.
Special table 2003-506552 gazette

  An object of this invention is to provide the measuring method which can measure the trace amount formaldehyde generated from the resin material which uses formaldehyde or its derivative as a raw material, or its molded article simply and with sufficient reproducibility.

  As a result of intensive studies to solve such problems, the present inventor can measure a trace amount of formaldehyde generated from a resin or a molded product thereof by a simple apparatus and method as described below. As a result, the present invention has been completed.

That is, the present invention includes an inert gas supply means (A), a sealed container (B) having an inert gas introduction pipe and a discharge pipe, and a heating means (C) that can heat the closed container (B) to a predetermined temperature. ), And an apparatus provided with a container (D) having an introduction pipe for the gas discharged from the sealed container (B) and holding water or an organic solvent therein, the following operations (1) to (4) are performed. After performing for a while, the formaldehyde absorbed in water or an organic solvent held in the container (D) is quantified, and converted into the generated amount per unit weight or unit surface area of the evaluation object, or a resin This is a method for measuring a trace amount of formaldehyde released from a molded article, and a measuring device having the above-mentioned (A), (B), (C) and (D) as basic components.
(1) Put a predetermined amount of resin or its molded product to be evaluated inside the sealed container (B),
(2) By heating the sealed container (B) to a predetermined temperature with the heating means (C), formaldehyde generated from the resin or its molded product is discharged from the discharge pipe together with the inert gas introduced from the inert gas introduction pipe. Drain,
(3) The exhaust gas is guided to the container (D) through the introduction pipe, and introduced into water or an organic solvent held in the container (D) to absorb formaldehyde.
(4) The gas after passing through the water or organic solvent is discharged.

  Hereinafter, the present invention will be described in detail. FIG. 1 is a schematic view showing an embodiment of a measuring apparatus used in the present invention. In the figure, (B) is a sealed container having an inert gas introduction pipe 1 and a discharge pipe 2, and the inert gas introduction pipe 1 is an inert gas supply means (A) (not shown), for example, It is connected to the active gas cylinder through a pressure reducing valve, a flow meter and the like. The sealed container (B) is introduced with a resin or a molded product 5 as a measurement target of the amount of formaldehyde generated.

  (C) is a heating means for the closed container (B) into which the resin or molded product to be measured is introduced, and an oil bath is preferable in terms of ease of temperature control. (D) is a container having an introduction pipe 3 for introducing the gas discharged from the sealed container (B) and holding water or an organic solvent therein. As shown in the figure, the container (D) is preferably a closed container provided with the discharge pipe 4, and a plurality of containers (D) can be connected. Formaldehyde generated from the resin or molded product introduced into the sealed container (B) is discharged from the discharge pipe 2 together with the inert gas, and is introduced into the water or organic solvent held in the container (D) through the gas introduction pipe 3. Formaldehyde is absorbed in water or organic solvents.

  In measuring formaldehyde generated from a resin or a molded article using such an apparatus, the capacity of the sealed container (B), the weight of the measuring resin or molded article put in the sealed container (B), the capacity of the container (D), the container The amount of water or organic solvent to be added to (D), the flow rate of the inert gas, the heating conditions (temperature, heating time) of the sealed container (B) in which the measurement resin or molded product is arranged are not particularly limited. However, in order to evaluate the resin or molded product by comparing the amount of generated formaldehyde with relative conditions, the measurement conditions for the group of resins or molded products to be evaluated are the same. Is necessary.

  Next, a method for measuring the amount of formaldehyde generated according to the present invention using such an apparatus will be described.

First, the resin or molded product to be measured is placed in the sealed container (B). Capacity of the sealed container (B) is generally may be selected from a range of 1～2000Cm ^3, preferably is convenient especially 10~100cm about ³ to handle. For example, a 50 cm ³ sealed container is used. Further, the amount of the resin to be measured or the molded product to be put in the sealed container (B) may be selected from the range of about 0.5 to 200 g, and particularly preferably a predetermined amount selected from the range of 0.5 to 50 g. For example, about 11 g is used. The sealed container (B) may be purged with an inert gas in advance, or may be purged after introducing a resin or a molded product.

  Next, the sealed container (B) into which the resin to be measured or the molded product is introduced is heated by the heating means (C), and is inert from the inert gas supply means (A) through the introduction pipe 1 of the sealed container (B). Gas is introduced and discharged through the discharge pipe 2 together with formaldehyde generated from the resin or molded product, and further introduced into the water or organic solvent held in the container (D) through the introduction pipe 3 of the container (D) to absorb formaldehyde. Let As a medium to be held in the container (D) in order to absorb formaldehyde, it is optimal to use water from the viewpoint of ease of handling, formaldehyde absorbability, and the like.

  Here, as the heating means, an oil bath is preferable in terms of easy temperature control. The heating temperature may be set in consideration of the melting characteristics of the resin and its quality (particularly the formaldehyde content and release amount). In the case of polyacetal resin, if you want to evaluate the amount of formaldehyde generated in a non-molten state When the heating temperature is about 40 to 150 ° C., preferably 60 to 140 ° C. and the amount of formaldehyde generated in the molten state is to be evaluated, the melting point of the resin (about 160 ° C.) to 250 ° C., preferably 190 to 210 ° C. It is preferable that the heating time is approximately 1 to 120 minutes, preferably 10 to 30 minutes. For example, heating conditions of 100 ° C. for 15 minutes in a non-molten state and 15 minutes at 200 ° C. in a non-molten state are used. If the heating conditions are too mild, the amount of formaldehyde generated will be too small and accurate measurement will be impossible. There arises a problem that the quantitativeness of formaldehyde is lowered.

As the inert gas used is economical to use nitrogen gas, approximately 0.1 - ³ / min, preferably preferably flow predetermined flow rate selected from the range of 100~500cm ³ / min .

The container (D) of the capacity is approximately 1～2000Cm ^3, preferably about 50 to 200 cm ^3, the amount of water or an organic solvent to hold the generally 5～1000Cm ^3, preferably 30～100Cm ³ approximately.

  After the formaldehyde absorbed in the water or organic solvent held in the container (D) by the above operation is measured by a known formaldehyde measurement method such as the acetylacetone method or the chromotropic acid method, and the absolute amount of formaldehyde generated is calculated The amount of formaldehyde generated per unit weight or surface area of the resin or molded article to be measured is obtained.

  A simple acetylacetone method for measuring absorbed formaldehyde is one in which formaldehyde is quantified by reacting an aqueous formaldehyde solution with acetylacetone in the presence of ammonium ions at pH 5.5 to 7.0 and colorimetrically determining the product.

EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.
Examples 1-4
Using the apparatus having the configuration shown in FIG. 1, measurement was performed under the following conditions and operating procedures.

The measurement results are shown in Table 1. According to the present invention, the measurement error is small, and the present invention can be used as a method for measuring formaldehyde generated from a resin or a molded product.
[Evaluation resin material]
A polyacetal resin (trade name; Duracon (registered trademark) M90S) manufactured by Polyplastics Co., Ltd. was used as a resin material, and a molded piece (127 mm × 12.7 mm × 0.8 mm) was molded by injection molding. The molded piece 1 and the molded piece 2 are formed by changing the date. In the evaluation, 12 pieces (about 10.9 g) obtained by cutting the molded piece into ½ were used.
〔conditions〕
Capacity of sealed container (B): 50 cm ³
Introduced resin amount: about 10.9 g (12 pieces of the above-mentioned molded piece cut in half are used and precisely weighed)
Capacity of container (D): 100 cm ³
Water volume in container (D): 60 cm ³
Heating temperature and time: 100 ° C. × 15 minutes Inert gas type and flow rate: nitrogen gas, 400 cm ³ / min [operation procedure]
a. The polyacetal resin molded product to be evaluated is introduced into the sealed container (B).

  b. An inert gas is supplied from the inert gas supply means to purge the system.

  c. Set the airtight container (B) in an oil bath, flow an inert gas while heating at a predetermined temperature for a predetermined time, introduce formaldehyde generated from the polyacetal resin molded product into the water of the container (D) together with the inert gas, and formaldehyde To absorb water.

  d. After a predetermined time, formaldehyde absorbed in the water in the container (D) is quantified by the acetylacetone method, and the absolute amount of formaldehyde generated is calculated.

  e. The amount of formaldehyde generated is converted to the amount generated per unit weight of the polyacetal resin molded product to be evaluated.

The schematic diagram which shows the one aspect | mode of the measuring apparatus used in this invention.

Explanation of symbols

(A) ... inert gas supply means (B) ... sealed container (C) ... heating means (D) for sealed container (B) ... container 1 ... inert gas introduction pipe 2 ... discharge pipe 3 ... exhausted gas Introducing pipe for introducing 4 ... Discharge pipe 5 ... Resin or molded product thereof

Claims (13)

An inert gas supply means (A), a sealed container (B) provided with an inert gas introduction pipe and a discharge pipe, a heating means (C) capable of heating the sealed container (B) to a predetermined temperature, and the sealed After performing the following operations (1) to (4) for a predetermined time using an apparatus including a container (D) having an introduction pipe for gas discharged from the container (B) and holding water or an organic solvent therein, The amount of formaldehyde absorbed in the water or organic solvent held in the container (D) is quantified and converted into the generated amount per unit weight or unit surface area of the object to be evaluated. Of trace formaldehyde.
(1) Put a predetermined amount of resin or its molded product to be evaluated inside the sealed container (B),
(2) By heating the sealed container (B) to a predetermined temperature by the heating means (C), formaldehyde generated from the resin or its molded product is discharged from the discharge pipe together with the inert gas introduced from the inert gas introduction pipe. Drain,
(3) The exhaust gas is guided to the container (D) through the introduction pipe, and introduced into water or an organic solvent held inside the container (D) to absorb formaldehyde,
(4) The gas after passing through the water or organic solvent is discharged. The method for measuring a trace amount of formaldehyde according to claim 1, wherein the inert gas is nitrogen gas. Measurement of trace formaldehyde according to claim 1 or 2 flow rate of the inert gas is 0.1 - ³ / min. The method for measuring trace formaldehyde according to any one of claims 1 to 3, wherein the sealed container (B) has a volume of 1 to 2000 cm ³ . The method for measuring a trace amount of formaldehyde according to any one of claims 1 to 4, wherein the amount of the resin or molded product thereof put in the sealed container (B) is 0.5 to 200 g. The method for measuring a trace amount of formaldehyde according to any one of claims 1 to 5, wherein the heating means (C) is an oil bath. The method for measuring a trace amount of formaldehyde according to any one of claims 1 to 6, wherein the heating temperature is a predetermined temperature within a range of 40 to 150 ° C. The method for measuring a trace amount of formaldehyde according to any one of claims 1 to 6, wherein the heating temperature is a predetermined temperature within a range of 160 to 250 ° C. The method for measuring a trace amount of formaldehyde according to any one of claims 1 to 8, wherein the container (D) has a volume of 1 to 2000 cm ³ . The method for measuring a trace amount of formaldehyde according to any one of claims 1 to 9, wherein the amount of water or organic solvent held in the container (D) is 5 to 1000 cm ³ . The method for measuring a trace amount of formaldehyde according to any one of claims 1 to 10, wherein formaldehyde absorbed in water or an organic solvent held in the container (D) is quantified by an acetylacetone method. The method for measuring a trace amount of formaldehyde according to any one of claims 1 to 11, wherein the resin or a molded product thereof is made of a polyacetal resin. An apparatus used for measuring a trace amount of formaldehyde released from a resin or a molded product thereof, which is an airtight container (B) provided with an inert gas supply means (A), an inert gas introduction pipe and an exhaust pipe. ), A heating means (C) capable of heating the sealed container (B) to a predetermined temperature, and a container (in which water or an organic solvent is held inside) provided with an introduction pipe for the gas discharged from the sealed container (B) D), a predetermined amount of a resin material or molded product to be evaluated is placed inside the sealed container (B), and the sealed container (B) is heated by the heating means (C) to thereby form the resin material or molded product. Formaldehyde generated from the product is discharged from the discharge pipe together with the inert gas introduced from the inert gas introduction pipe, and this is guided to the container (D) through the introduction pipe of the container (D) and held inside the container (D) In water or organic solvent The amount of formaldehyde generated from the resin material or molded article can be measured by absorbing formaldehyde and measuring the formaldehyde in the absorption liquid, and the gas that has passed through the water or organic solvent is discharged. apparatus.

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