Method for evaluating residual oiliness, method for evaluating residual oiliness of container or pipe, and method for manufacturing container or pipe

Abstract

To provide a method for evaluating residual oiliness.SOLUTION: A method for evaluating residual oiliness, comprises moving oil droplets on a sample surface inclined at 45 to 85° with respect to a vertical direction, and observing a rear end of the moving oil droplets. It is preferable that the observation of the rear end of the oil droplets is performed by measuring parameters selected from a distance traveled by the rear end of the oil droplets moving on the sample surface in a certain time, a travel time of the rear end of the oil droplets moving on the sample surface in a certain distance, and an area of the rear end of the oil droplets near a start position after the certain time.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for evaluating residual oil properties, and more particularly to a method for evaluating the residual oil properties of a container or a pipe. [Background technology]

[0002] In recent years, in order to reduce the environmental load, recycling and reuse of used containers have been conducted. On the other hand, since oils and fats have poor hydrophilicity and are not easy to clean, containers that can remove as much oil and fat as possible from containers containing oil and fats have been developed. In the development of these containers or in the quality control process for evaluating the residual oiliness of manufactured containers, a method for evaluating the residual oiliness that can be appropriately evaluated is required.

[0003] The oil remaining property of a container can be easily evaluated by taking out the oil from a container filled with oil and measuring its weight. For example, Patent Document 1 discloses an example in which the time since tilting a container containing oil is used as the horizontal axis and the amount of oil remaining in the container as the vertical axis for evaluation. However, with this method, oil is poured in during the process of tilting the container, and it is difficult to set conditions for more accurate comparison. On the other hand, it is thought that the oil remaining property is affected by the physical properties of the (inner) surface of the container. Patent Document 2 describes an invention of a coating resin composition that is excellent in water and oil repellency as well as water sliding properties, and there is an example in which edible rapeseed oil is attached to a coating film and the moving distance of a droplet on a surface tilted at 9.5° is measured as an evaluation of "oil sliding property". [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2022-128116 A [Patent Document 2] JP 2014-31418 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, unlike water, oil droplets have a low surface tension and tend to spread widely. Therefore, when moving on an inclined surface, the rear end moves slower than the front end in the direction of travel that is in contact with the surface, and the front end moves before the rear end. The evaluation of "oil slipperiness" described in Patent Document 2 is expressed without using "slippage" as in the evaluations of "water sliding angle" and "amount of sliding water" in the same document, and considering that there is no difference in the value of "oil slipperiness" between Example 1 and Comparative Example 4, it is considered that the evaluation is based on the moving distance of the tip of the droplet, and it was not possible to evaluate the residual oil.

[0006] Therefore, an object of the present invention is to provide a method for evaluating residual oil properties. [Means for solving the problem]

[0007] The present invention which solves the above problems is as follows. [1] A method for evaluating residual oil properties, comprising the steps of: The oil droplet is moved on the sample surface at an inclination of 45 to 85 degrees from the vertical. A method for evaluating oil residue, comprising observing the trailing edge of a moving oil droplet. [2] The method for evaluating oil residuality according to [1], wherein the observation of the rear end of the oil droplet comprises measuring a parameter selected from the distance traveled by the rear end of the oil droplet moving across the sample surface in a certain period of time, the travel time of the rear end of the oil droplet moving across the sample surface over a certain distance, and the area of ​​the rear end of the oil droplet near the starting position after the certain period of time. [3] The method for evaluating oil retention in accordance with [1], in which the sample surface is flat. [4] The method for evaluating oil residual property according to [1], wherein the amount of the oil droplets is 10 to 50 mg. [5] The method for evaluating oil retention according to [2], wherein the certain time is 1 second or longer, or the certain distance is 2 mm or longer. [6] The method for evaluating residual oiliness according to [1], wherein the oil droplets are colored with a coloring agent. [7] A method for evaluating the residual oil properties of a container or piping using any of the residual oil properties evaluation methods [1] to [6]. [8] A method for manufacturing a container or piping, comprising a quality control step of evaluating the surface of the container or piping using any one of the methods for evaluating residual oiliness [1] to [6]. Effect of the Invention

[0008] According to the present invention, it is possible to evaluate the residual oil property. When the leading edge of the oil is observed during the movement of the oil, the remaining part at the trailing edge cannot be evaluated, but by observing the trailing edge, the residual oil property can be evaluated, and the residual oil property of the container can be accurately measured. [Brief description of the drawings]

[0009] [Figure 1] 1 is a diagram showing the direction of droplet movement on a sample surface and the angle between the direction and the vertical direction. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The method for evaluating oil residual property according to the present invention is characterized in that an oil droplet is moved on a sample surface inclined at an angle of 45 to 85° with respect to the vertical direction, and the trailing end of the moving oil droplet is observed.

[0011] (Sample surface) In the present invention, the "sample surface" refers to the surface of a sample for measuring residual oil. The sample surface is not particularly limited, but is preferably the surface itself that comes into contact with oil, such as a container or pipe, or an evaluation sample having a similar surface state, and more preferably the surface of a container in which oil is placed, and most preferably the inner surface of a container in which oil is placed. The sample preferably contains plastic, metal, paper, china clay, glass, etc. as a main component, and more preferably has a surface covered with an oil-repellent coating.

[0012] In the present invention, an oil droplet moves on the sample surface, and the rear end of the oil droplet is observed. At this time, the sample surface is set so that the oil droplet moves on the sample surface at an inclination of 45 to 85° with respect to the vertical direction, and the oil droplet moves on the sample surface along this inclination. When the angle at which the droplet moves is in the range of 45 to 85° with respect to the vertical direction, the movement speed of the oil droplet is in a range in which it is easy to measure. When the inclination is more gradual than 85° with respect to the vertical direction, it becomes difficult for the rear end to move. It is preferable to set the sample surface so that the oil droplet moves on the sample surface at an inclination of 60 to 85° with respect to the vertical direction, and it is more preferable to set the sample surface so that the oil droplet moves on the sample surface at an inclination of 65 to 75° with respect to the vertical direction.

[0013] The oil droplets may be dropped on a sample surface inclined at 45 to 85 degrees from the vertical, or may be dropped on a sample surface placed horizontally and then inclined at 45 to 85 degrees from the vertical for measurement. The sample to be measured may be measured as is, or a smooth part may be cut out and measured as a sample on a flat or nearly flat plate. A known method may be used to incline the sample at 45 to 85 degrees from the vertical, but for example, the "Stage AG85 (angle inclination)" manufactured by AS ONE Corporation may be used.

[0014] In the present invention, the sample surface may be uneven, but it is preferable that the oil droplets move on the sample surface at an inclination of 45 to 85° with respect to the vertical direction. For example, the surface may have a valley-shaped depression, and the oil droplets may move along the valley of the surface, with the movement path of the oil droplets being inclined at 45 to 85° with respect to the vertical direction. It is preferable that the part of the sample surface along which the oil droplets move during measurement (movement path) is a straight line, and it is more preferable that the sample surface is flat. For example, the flat part of a container containing fats and oils as its content may be used as the sample surface, and the flat part of the container may be cut as necessary and used. In addition, the size of the sample surface may be large enough to observe the rear end of the moving oil droplets. The length in the movement direction of the oil droplets may be equal to or greater than the movement distance of the oil droplets to be observed, and may be, for example, 1 cm or more, 2 cm or more, 4 cm or more, 1 to 100 cm, 2 to 50 cm, 2 to 20 cm, 4 to 10 cm, etc. Furthermore, the length in the direction perpendicular to the direction of movement of the oil droplet (the width of the sample surface) may be any width greater than the width over which the oil droplet spreads laterally, for example, 0.5 cm or more, 1 cm or more, 4 cm or more, 5 cm or more, 0.5 to 20 cm, 3 to 10 cm, 4 to 6 cm, etc.

[0015] (oil drop) In the present invention, oil droplets are attached to the sample surface and moved, and the oil droplets used may be mineral oil, animal and vegetable oil, synthetic oil, processed oils and fats thereof, or mixed oils. It is preferable to use oils and fats that are usually in contact with the surface to be measured, but there is no limitation as long as they have similar properties. For example, in the case of a container for edible oil, animal and vegetable oils or processed oils and fats thereof can be used, and liquid vegetable oils such as soybean oil, rapeseed oil, corn oil, sesame oil, olive oil, sunflower oil, linseed oil, and safflower oil are more preferable.

[0016] In addition, the oil droplets to be attached can be colored with a pigment, dye, or the like to improve visibility during measurement. For example, when colorless or light-colored edible oil is used, the oil droplets can be colored with carotene, which dissolves in the edible oil. The amount of the coloring component added is small and does not affect the residual oil property, so there is no particular limitation, but the amount is preferably 5% by mass or less of the oil droplet, and more preferably 1% by mass or less of the oil droplet.

[0017] The amount of oil droplets is not particularly limited, but is preferably 10 to 50 mg, more preferably 10 to 40 mg, further preferably 15 to 40 mg, and particularly preferably 15 to 30 mg. The oil droplets can be attached to the sample using a dropper, pipette, or the like.

[0018] (Observation and Evaluation) In the present invention, the rear end of the moving oil droplet is observed. The observation of the rear end of the oil droplet is preferably performed by measuring a parameter selected from the moving distance of the rear end of the oil droplet moving on the sample surface in a certain time, the moving time of the rear end of the oil droplet moving on the sample surface in a certain distance, and the change in area of ​​the rear end of the oil droplet near the starting position after a certain time.

[0019] Although the measured moving distance and moving time are not particularly limited, the longer the moving time and the longer the moving distance, the easier it is to compare the effects, so the moving time is preferably 1 second or more, more preferably 5 seconds or more, and even more preferably 10 seconds or more. The moving distance is preferably 2 mm or more, more preferably 3 mm or more, and even more preferably 5 mm or more. Since rapid observation is sometimes preferred, the migration time is preferably 1 to 3600 seconds, more preferably 5 to 1200 seconds, and even more preferably 10 to 600 seconds. From the viewpoint of rapid observation, the migration distance is preferably 2 to 200 mm, more preferably 3 to 20 mm, and even more preferably 4 to 10 mm. The aforementioned fixed time and fixed distance can be appropriately selected from the above ranges.

[0020] In the present invention, the residual oil property is observed at the rear end of the oil droplet, and there are many surfaces with high residual oil property, not only those in which both the front and rear ends of the oil droplet are difficult to move, but also those in which the front end of the oil droplet moves quickly but the rear end of the oil droplet moves slowly. Therefore, it can be evaluated by comparing the area of ​​the rear end of the oil droplet near the start position. The vicinity of the start position can be appropriately set, for example, within a range that includes the area of ​​the oil droplet when the oil droplet is attached, or within a range of 50% or less from the start position of the movement distance to be measured. The rear end of the oil droplet may be any position closer to the rear end than between the front and rear ends of the oil droplet.

[0021] In the present invention, the longer the distance traveled in a given time by the rear end of the oil droplet moving on the sample surface, the less the residual oil can be determined. Also, the shorter the travel time of the rear end of the oil droplet moving on the sample surface in a given distance, the less the residual oil can be determined. Also, the smaller the area of ​​the rear end of the oil droplet near the start position after a given time, the less the residual oil can be determined. For example, a sample is placed on a stage ("Stage (angle inclination" manufactured by AS ONE Corporation) set at an inclination of 70° with respect to the vertical direction, and the time it takes for the rear end of the oil droplet (the uppermost contact point between the sample surface and the oil droplet on the inclined sample surface) to move 6 mm on the sample surface is measured. The shorter the time, the better the oil slides off and the less residual oil is evaluated to be. For example, the order of the movement time is more than 60 to 300 seconds, more than 20 to 60 seconds, more than 10 to 20 seconds, and 10 seconds or less, which indicates good oil slides off and less residual oil.

[0022] (Other conditions) In the present invention, the measurement temperature may be any condition that allows the oil droplets to move on the sample surface, and if the oil droplets are liquid, the measurement may be performed at room temperature (e.g., 0 to 30° C.). If the melting point of the oil droplets is higher than room temperature, the measurement may be performed at a temperature equal to or higher than the melting point.

[0023] In the present invention, the rear end of the oil droplet may be observed visually, or may be videotaped and analyzed by image analysis or the like.

[0024] (Manufacturing method of containers or piping) In the present invention, the method for evaluating residual oil properties is preferably used as a method for evaluating the residual oil properties of a container or a pipe. Also, it can be used in a quality control step for evaluating the surface of a container or a pipe. By including the quality control step in the method for manufacturing a container or a pipe, it is possible to stably manufacture a container or a pipe with controlled residual oil properties, which is preferable.

[0025] The present invention will be described in more detail below with reference to examples, but the technical scope of the present invention is not limited to the following examples.

[0026] (Slip resistance 1) A flat portion (2 cm x 2 cm) was cut out from the PET container (uncoated sample) or the PET container coated with a silicon oxide vapor deposition film (coated samples 1 to 5) to obtain a sample. The sample was placed on a stage ("Stage (angle inclination)" manufactured by AS ONE Corporation) set at an inclination of 70° from the vertical direction, and a drop (approximately 24.36 mg) of refined rapeseed oil ("Nissin Canola Oil" manufactured by Nisshin Oillio Group, Ltd., 99.9%) colored with carotene ("β-Carotene 30% FS" manufactured by DMS, 0.1%) was dropped onto the surface of the sample using a dropper. The time (seconds) for the tip of the oil droplet (the point of contact between the oil droplet and the sample surface at the lowest position) and the rear end of the oil droplet (the point of contact between the oil droplet and the sample surface at the highest position) to move 6 mm on the sample surface was measured and shown in Table 1. The temperature during the measurement was room temperature (23°C). The shorter the migration time, the lower the residual oil property. Evaluation is performed based on the following criteria A to E. If the evaluation is A to D, the residual oil property can be determined to be low. A rating: Rear end movement time is within 10 seconds B rating: Rear end movement time is over 10 to 20 seconds C rating: Rear end movement time is over 20 to 60 seconds D rating: Rear end movement time is over 60 seconds to 300 seconds E rating: Rear end movement time exceeds 300 seconds

[0027] [Table 1]

[0028] As shown in Table 1, the front moves fast but the rear end moves slowly, making it difficult to evaluate based on the front alone. On the other hand, by evaluating the travel time of the rear end, it becomes easier to judge the residual oil content.

[0029] (Slip resistance 2) Samples were cut out from PET containers coated with silicon oxide vapor deposition films (coated samples 1, 4, and 5) in the same manner as in sliding property 1, and measurements were taken in the same manner as sliding property 1, except that the inclination of sliding property 1 was changed to 80° with respect to the vertical direction. The results are shown in Table 2.

[0030] [Table 2]

[0031] As shown in Table 2, the front end moves fast, but the rear end moves slowly, making it difficult to evaluate based on the front end alone. On the other hand, by evaluating the travel time of the rear end, it becomes easier to judge the residual oil content.

Claims

1. A method for evaluating residual oil properties, comprising the steps of: The oil droplet was moved on the sample surface at an inclination of 45 to 85 degrees from the vertical. A method for evaluating oil residue, comprising observing the trailing edge of a moving oil droplet.

2. The method for evaluating oil residual property according to claim 1, wherein the observation of the rear end of the oil droplet comprises measuring a parameter selected from the distance traveled by the rear end of the oil droplet moving across the sample surface in a certain time period, the travel time of the rear end of the oil droplet moving across the sample surface in a certain distance, and the area of ​​the rear end of the oil droplet near the starting position after the certain time period.

3. The method for evaluating oil remaining property according to claim 1 , wherein the sample surface is flat.

4. The method for evaluating oiliness according to claim 1, wherein the amount of the oil droplets is 10 to 50 mg.

5. The method for evaluating oil residual property according to claim 2 , wherein the certain time is 1 second or more, or the certain distance is 2 mm or more.

6. The method for evaluating oiliness according to claim 1 , wherein the oil droplets are colored with a coloring agent.

7. A method for evaluating residual oil properties of a container or a pipe, comprising evaluating the residual oil properties by using the method for evaluating residual oil properties according to any one of claims 1 to 6.

8. A method for manufacturing a container or piping, comprising the steps of: A method for manufacturing a container or piping, comprising a quality control step of evaluating the surface of the container or piping using the method for evaluating residual oil properties according to any one of claims 1 to 6.

Images