Method for estimating the carbon black content in a resin sample

Abstract

This invention provides a method for estimating the carbon black content in a resin sample, which can be applied even to resin samples with low carbon black content. [Solution] A method for estimating the carbon black content in a resin sample includes: determining the infrared transmittance of the resin sample by performing infrared spectroscopic analysis of the resin sample; and estimating the carbon black content in the resin sample using the infrared transmittance of the resin sample and a predetermined correlation between the infrared transmittance and the carbon black content.

Description

[Technical Field]

[0001] This disclosure relates to a method for estimating the carbon black content in a resin sample. [Background technology]

[0002] With the growing need for a sustainable, resource-recycling society, realizing a circular economy using recycled resins is urgently required. Ideally, recycled resins should be color-matched to the desired shade. However, if the recycled resin contains carbon black derived from the raw materials, achieving high brightness in the recycled resin is difficult.

[0003] Patent Document 1 describes how to quantify the carbon black content of a rubber composition using the 13C-NMR DD / MAS method. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2017-043782 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] To streamline the color matching process for recycled resins, it is desirable to quantify the carbon black contained in recycled resins or used resins used as raw materials. Generally, the carbon black content of recycled resins or used resins used as raw materials is 5 wt% or less. The quantitative method described in Patent Document 1 has difficulty accurately quantifying the carbon black content when it is as low as 5 wt%, and therefore, it has been difficult to apply the quantitative method described in Patent Document 1 to recycled resins or used resins used as raw materials.

[0006] In light of the above, this disclosure provides a method for estimating the carbon black content in a resin sample, which is also applicable to resin samples with low carbon black content. [Means for solving the problem]

[0007] The forms of this disclosure include the following: [Aspect 1] A method for estimating the carbon black content in a resin sample, The infrared transmittance of the resin sample is determined by performing infrared spectroscopic analysis of the resin sample, The carbon black content in the resin sample is estimated using the infrared transmittance of the resin sample and the correlation between the infrared transmittance and the carbon black content, which has been previously determined. Methods that include... [Aspect 2] The method according to embodiment 1, wherein the correlation between the infrared transmittance and the carbon black content is determined by performing infrared spectroscopic analysis of a plurality of standard resin samples with known carbon black content to determine the infrared transmittance of the plurality of standard resin samples. [Aspect 3] The aforementioned infrared transmittance is 2743 cm⁻¹ in the infrared absorption spectrum. -1 ~1472cm -1 The line connecting the absorbance values ​​at 2067 cm² is used as the baseline. -1 The method according to embodiment 1 or 2, determined from the absorbance in [location]. [Aspect 4] The method according to any one of embodiments 1 to 3, wherein the carbon black content in the resin sample is 5 wt% or less. [Aspect 5] The method according to any one of embodiments 1 to 4, wherein the resin sample consists of recycled resin or used resin used as a raw material for recycled resin. [Effects of the Invention]

[0008] The carbon black content estimation method described herein is also applicable to resin samples with low carbon black content.

Brief Description of the Drawings

[0009] [Figure 1] FIG. 1 is a graph showing the correlation between the infrared transmittance and the carbon black content of the resin sample used in the examples.

Embodiments for Carrying Out the Invention

[0010] In the present application, "comprising" and "containing" mean that additional components or elements may be included unless otherwise specified, and include "mainly comprising" and "consisting of". "Mainly comprising" means that the content of the described material or element is more than 50 wt%. "Consisting of" means containing only the described material or element, but does not exclude further containing unavoidable impurities.

[0011] (1) Resin sample First, the resin sample used in the method according to the embodiment will be described.

[0012] The resin sample may be composed of recycled resin or used resin used as a raw material for recycled resin. The carbon black content in the resin sample is not particularly limited, and for example, it may be 5 wt% or less or less than 5 wt%.

[0013] The resin sample mainly contains any resin. For example, it may mainly contain an olefin resin, a styrene resin, or an ester resin. Examples of olefin resins include polypropylene resins such as propylene homopolymer (homopolypropylene), propylene-α-olefin copolymer (random polypropylene), and propylene block copolymer (block polypropylene). Examples of styrene resins include polystyrene resin. Examples of ester resins include polyethylene terephthalate, polybutylene terephthalate, polybutylene succinate, polyethylene naphthalate, and polylactic acid.

[0014] The resin sample may further contain components such as additives and fillers. Examples of additives include antioxidants, neutralizing agents, light stabilizers, ultraviolet absorbers, crystal nucleating agents, antiblocking agents, lubricants, antistatic agents, and metal deactivators. These additives may be used alone or in combination of two or more. Examples of fillers include inorganic fillers such as calcium carbonate, silica, hydrotalcite, zeolite, aluminum silicate, magnesium silicate, glass fiber, and carbon fiber, and organic fillers such as crosslinked rubber fine particles, thermosetting resin fine particles, and hollow thermosetting resin fine particles.

[0015] The resin sample may have a plate shape. The dimensions of the resin sample may be appropriately set so that the resin sample can be subjected to infrared spectroscopic analysis. For example, when the carbon black content in the resin sample is large, the thickness of the resin sample may be reduced so that the infrared transmission intensity of the resin sample becomes sufficiently large.

[0016] (2) Method for estimating carbon black content in resin sample The method for estimating the carbon black content in the resin sample according to the embodiment includes performing infrared spectroscopic analysis on the resin sample to obtain the infrared transmittance of the resin sample (S1), and using the infrared transmittance of the resin sample and the correlation between the infrared transmittance and the carbon black content specified in advance to estimate the carbon black content in the resin sample (S2).

[0017] (2-1) Specifying the infrared transmittance of the resin sample (S1) The resin sample is subjected to Fourier transform infrared spectroscopy (FT-IR) to obtain the infrared transmittance of the resin sample. For example, the infrared transmittance of the resin sample can be obtained as follows.

[0018] An infrared absorption spectrum of the resin sample is obtained by FT-IR. In the obtained infrared absorption spectrum, a straight line connecting the absorbances at 2743 cm -1 ~1472 cm -1 is used as the baseline, and at 2067 cm -1Determine the absorbance at 2067 cm². -1 Calculate the transmittance at this 2067cm². -1 The transmittance in this case is used as the infrared transmittance of the resin sample to estimate the carbon black content in subsequent measurements.

[0019] (2-2) Estimation of carbon black content (S2) Next, the carbon black content in the resin sample is estimated using the infrared transmittance of the resin sample identified as described above, and the correlation between the previously identified infrared transmittance and the carbon black content.

[0020] The correlation between infrared transmittance and carbon black content can be determined in advance, for example, as follows.

[0021] Prepare several standard resin samples with known carbon black content. The standard resin samples mainly contain the same components as the main components of the resin samples used to estimate the carbon black content. The standard resin samples may also contain the same additives, fillers, and other components as the resin samples used to estimate the carbon black content. The standard resin samples may have the same thickness as the resin samples used to estimate the carbon black content.

[0022] The infrared transmittance of each standard resin sample is determined. The infrared transmittance of the standard resin sample is determined in the same manner as the infrared transmittance of the resin sample described above. From the infrared transmittance and carbon black content of each standard resin sample, the correlation between infrared transmittance and carbon black content is identified. That is, a calibration curve is created for determining the carbon black content from the infrared transmittance. It should be noted that the correlation between the infrared transmittance and carbon black content of resin samples is also shown in the examples described later.

[0023] This disclosure is not limited to the embodiments described above, and various modifications, additions, and deletions may be made without departing from the technical scope set forth in the claims. [Examples]

[0024] Hereinafter, the present disclosure will be specifically described by way of examples, but the present disclosure is not limited to these examples.

[0025] Samples (thickness: 3 mm) of polypropylene resin containing carbon black in the amounts shown in Table 1 were prepared.

[0026] The infrared absorption spectrum of the sample was obtained using a Fourier transform infrared spectrometer (INVENIO S manufactured by BRUKER). The measurement conditions were as follows.

[0027] Wavenumber: 400 cm -1 ~4000 cm -1 Resolution: 4 cm -1 Number of accumulations: 128 scans Detector: DLaTGS

[0028] In the infrared absorption spectrum of each sample, the absorbance at 2067 cm was determined using the straight line connecting the absorbances at 2743 cm -1 ~1472 cm -1 as the baseline. Based on this, the transmittance at 2067 cm of each sample was determined. The results are shown in Table 1. -1 -1 -1 -1

[0029] [Table 1]

[0030] Fig. 1 shows a graph with the carbon black content on the horizontal axis and the infrared transmittance on the vertical axis. It was shown from Fig. 1 that there is a correlation between the infrared transmittance of the sample and the carbon black content (see Fig. 1). The coefficient of determination R 2 was approximately 0.9994. Therefore, it is understood that the carbon black content in the resin sample can be determined based on the infrared transmittance.

Claims

1. A method for estimating the carbon black content in a resin sample, The infrared transmittance of the resin sample is determined by performing infrared spectroscopic analysis of the resin sample, The carbon black content in the resin sample is estimated using the infrared transmittance of the resin sample and the correlation between the infrared transmittance and the carbon black content, Methods that include...

2. The method according to claim 1, wherein the correlation between the infrared transmittance and the carbon black content is determined by performing infrared spectroscopic analysis of a plurality of standard resin samples with known carbon black content to determine the infrared transmittance of the plurality of standard resin samples.

3. The aforementioned infrared transmittance is 2743 cm⁻¹ in the infrared absorption spectrum. －１ ~1472cm －１ The line connecting the absorbance values ​​at 2067 cm² is used as the baseline. －１ The method according to claim 1 or 2, determined from the absorbance in [location].

4. The method according to claim 1 or 2, wherein the carbon black content in the resin sample is 5 wt% or less.

5. The method according to claim 1 or 2, wherein the resin sample consists of recycled resin or used resin used as a raw material for recycled resin.

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