Hydrophilization method

Abstract

To provide a hydrophilization method capable of sustaining hydrophilic effect. [Solution] A predetermined material 2 is subjected to plasma treatment to modify the surface of the predetermined material 2 and form hydrophilic groups 2a. Then, a predetermined reagent 3 is combined with the predetermined material 2 on which the hydrophilic groups 2a have been formed, and dehydration condensation is carried out. As a result, the predetermined reagent 3 is bonded to the hydrophilic groups 2a formed in conjunction with the surface modification of the predetermined material 2. Thus, by doing this, the hydrophilic effect can be sustained.

Description

[Technical Field]

[0001] The present invention relates to a hydrophilization method that can maintain the hydrophilic effect of a given material. [Background technology]

[0002] Conventionally, a method for improving hydrophilicity by introducing hydrophilic groups such as —OH by a method such as plasma treatment has been known (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Unexamined Patent Publication No. 63-80216 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the above method has a problem in that the hydrophilic effect disappears within a few hours to about 3 days, and is not long-lasting.

[0005] In view of the above problems, an object of the present invention is to provide a hydrophilization method that can maintain the hydrophilic effect. [Means for solving the problem]

[0006] The above object of the present invention can be achieved by the following means: Note that the parentheses indicate reference symbols of embodiments to be described later, but the present invention is not limited to these.

[0007] The hydrophilization method according to claim 1 comprises: When forming the side chain (2c) on the surface of the polyethylene terephthalate, To the surface of the polyethylene terephthalate, By performing plasma treatment, Polyethylene terephthalate A step of performing surface modification to form hydrophilic groups (2a); The hydrophilic group (2a) is formed Polyethylene terephthalate On the other hand, 2-Methacryloyloxyethyl phosphorylcholine and performing dehydration condensation; By carrying out the above-mentioned process, the side chains (2c) are formed on the surface of the polyethylene terephthalate. It is characterized by the following.

[0008] The hydrophilization method according to claim 2 is the hydrophilization method according to claim 1, wherein the hydrophilic group (2a) is formed on the Polyethylene terephthalate In contrast, 2-Methacryloyloxyethyl phosphorylcholine In combining the above 2-Methacryloyloxyethyl phosphorylcholine are hydrolyzed and then combined. [Effects of the Invention]

[0009] Next, the effects of the present invention will be described with reference to the drawings. Note that the reference symbols in parentheses are those of the embodiments described below, but the present invention is not limited to these.

[0010] According to the invention of claim 1, the hydrophilic group (2a) is formed. Polyethylene terephthalate On the other hand, 2-Methacryloyloxyethyl phosphorylcholine By combining these and performing dehydration condensation, Side chains (2c) are formed on the surface of polyethylene terephthalate. This means: Polyethylene terephthalate This makes it difficult for the hydrophilic groups (2a) to penetrate into the gaps (2b) on the surface.

[0011] Therefore, according to the present invention, the hydrophilic effect can be maintained.

[0012] According to the invention of claim 2, the hydrophilic group (2a) is formed. Polyethylene terephthalate In contrast, 2-Methacryloyloxyethyl phosphorylcholine In combining the 2-Methacryloyloxyethyl phosphorylcholine Since the hydrolyzed groups are combined, when dehydration condensation is carried out, the hydrophilic group (2a) 2-Methacryloyloxyethyl phosphorylcholine can be reliably bonded. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a schematic diagram for explaining a vacuum plasma device. [Figure 2] FIG. 1 is a graph confirming the durability of the hydrophilic effect obtained by a conventional hydrophilization method. [Figure 3] FIG. 1(a) is an explanatory diagram showing a predetermined material on which hydrophilic groups are formed, and FIG. 1(b) is an explanatory diagram showing a predetermined material on which a hard coat treatment has been performed to form hydrophilic groups. [Figure 4] FIG. 2 is an explanatory diagram showing a predetermined material in which a side chain is bonded to a hydrophilic group. [Figure 5] FIG. 1 is an explanatory diagram illustrating a method for forming side chains using polyethylene terephthalate (PET) as an example. [Figure 6] FIG. 10 is a graph showing the durability of the hydrophilic effect obtained by the hydrophilization method of the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0014] An embodiment of the hydrophilization method according to the present invention will be specifically described below with reference to the drawings. In the following description, when directions such as up, down, left, and right are indicated, they refer to up, down, left, and right when viewed from the front of the illustration.

[0015] <Explanation of conventional hydrophilization methods> First, a conventional hydrophilization method will be described.

[0016] To perform hydrophilization, a vacuum plasma device 1 as shown in Fig. 1 is prepared. This vacuum plasma device 1 includes a chamber 1a, the interior of which is vacuum, as shown in Fig. 1, and a predetermined material 2 is placed in this chamber 1a. An AC voltage 1b is applied to the chamber 1a to generate plasma, and the surface of the predetermined material 2 is subjected to plasma treatment. Examples of the gas 1c introduced into the chamber 1a shown in Fig. 1 include nitrogen and water vapor.

[0017] Thus, when the surface of the predetermined material 2 is subjected to plasma treatment in this manner, hydrophilic groups 2a (illustrated as —OH in the drawing) are formed on the surface of the predetermined material 2, as shown in FIG.

[0018] Here, a case where polyethylene terephthalate (PET) is used as the predetermined material 2 will be described.

[0019] When plasma treatment is performed on the surface of a predetermined material 2 made of polyethylene terephthalate (PET), hydrophilic groups 2a are formed as shown in Fig. 2. The graph shown in Fig. 2 confirms the change in contact angle (wettability) of the predetermined material 2 made of polyethylene terephthalate (PET) on which the hydrophilic groups 2a have been formed.

[0020] As shown in Figure 2, in the case of polyethylene terephthalate (PET) that has not been subjected to plasma treatment, the contact angle (wettability) of the specified material 2 is large, resulting in a low hydrophilic effect. In addition, in the case of polyethylene terephthalate (PET) that has been subjected to plasma treatment, the contact angle (wettability) of the specified material 2 is initially low, but from the first day onwards, the contact angle (wettability) gradually increases. Therefore, the results shown in Figure 2 indicate that the hydrophilic effect of plasma-treated polyethylene terephthalate (PET) is not sustained for long.

[0021] Therefore, the inventors performed plasma treatment on hard-coated polyethylene terephthalate (PET) as the predetermined material 2. As a result, as shown in FIG. 2, in the case of hard-coated polyethylene terephthalate (PET) that was not plasma-treated, the contact angle (wettability) of the predetermined material 2 was large, resulting in a low hydrophilic effect. However, in the case of hard-coated polyethylene terephthalate (PET) that was plasma-treated, the contact angle (wettability) of the predetermined material 2 remained low for 60 days. Therefore, the results shown in FIG. 2 demonstrate that the hydrophilic effect can be maintained in the case of hard-coated polyethylene terephthalate (PET) that was plasma-treated.

[0022] Based on this result, the present inventors came to the following conclusion.

[0023] The reason why plasma-treated polyethylene terephthalate (PET) was unable to maintain its hydrophilic effect is thought to be that the hydrophilic groups 2a penetrate into the gaps 2b on the surface of the specified material 2, as shown in Figure 3(a).

[0024] On the other hand, the reason why polyethylene terephthalate (PET) that has been subjected to plasma treatment and hard coating treatment can maintain its hydrophilic effect is thought to be as follows: As shown in Figure 3(b), the hard coating treatment prevents the formation of gaps 2b as shown in Figure 3(a) on the surface of the specified material 2. This prevents the hydrophilic groups 2a from penetrating as shown in Figure 3(a), which is thought to be why the hydrophilic effect can be maintained.

[0025] From the above, it is considered that in order to maintain the hydrophilic effect, it is sufficient to have a surface structure that does not allow the hydrophilic groups 2a to penetrate.

[0026] Therefore, the present inventors investigated whether it is possible to create a structure that the hydrophilic group 2a cannot penetrate into, even for a general material that has not been hard-coated. The result is the hydrophilization method according to the present embodiment, which will be described below.

[0027] <Explanation of hydrophilicity method> Next, the hydrophilization method according to this embodiment will be described.

[0028] The present inventors have investigated whether a structure into which the hydrophilic group 2a cannot penetrate can be created, and as a result, have come up with the idea of ​​the structure shown in FIG.

[0029] That is, as shown in Figure 4, the structure is such that side chains 2c are formed on the surface of the predetermined material 2 and bonded to hydrophilic groups 2a. In this way, it is thought that the side chains 2c prevent the hydrophilic groups 2a from entering the gaps 2b on the surface of the predetermined material 2. Therefore, it is thought that the hydrophilic effect can be maintained.

[0030] Thus, the present inventors came up with the following method for forming the side chains 2c as described above: Hereinafter, an example of the predetermined material 2 will be described using polyethylene terephthalate (PET).

[0031] First, a vacuum plasma device 1 as shown in FIG. 1 is used to perform plasma treatment on the surface of polyethylene terephthalate (PET) having the structural formula shown below.

[0032] [ka]

[0033] Thus, by carrying out the above-described plasma treatment, hydrophilic groups 2a are formed as shown in Figure 5. Polyethylene terephthalate (PET) on which hydrophilic groups 2a (see Figure 5) are formed has the following structural formula:

[0034] [ka]

[0035] Then, polyethylene terephthalate (PET) having hydrophilic groups 2a (see FIG. 5) formed thereon and having such a structural formula is combined (reacted) with a reagent 3 (see FIG. 5) having the structural formula shown below.

[0036] [ka]

[0037] Reagent 3, which has the above structural formula, is made of the zwitterionic polymer 2-methacryloyloxyethyl phosphorylcholine.

[0038] When combining the reagent 3 having the above structural formula, the reagent 3 is hydrolyzed as shown in FIG. 5. Specifically, the reagent 3 is diluted with water or the like. For example, the reagent 3 is diluted to a concentration of 10% and pure water to a concentration of 90%. In this way, the reagent 3 is hydrolyzed. This results in the following structural formula:

[0039] [ka]

[0040] Next, polyethylene terephthalate (PET) having hydrophilic groups 2a (see FIG. 5) formed therein and having the structural formula (2) above is combined with reagent 3 having the structural formula (4) above shown in FIG. 5, and dehydration condensation is carried out using a drying device (not shown) or the like. Thus, by the dehydration condensation reaction, polyethylene terephthalate (PET) having hydrophilic groups 2a (see FIG. 5) formed therein and having the structural formula (4) above shown in FIG. 5 are bonded to produce a product with the structural formula shown below.

[0041] [ka]

[0042] That is, as shown in Figure 5, a hydrophilic group 2a formed on the surface of polyethylene terephthalate (PET) is bonded to a side chain 2c. In this way, as shown in Figure 5, the side chain 2c of the molecule bonded to the hydrophilic group 2a is long, so it is thought that the hydrophilic group 2a is unlikely to penetrate into the gap 2b on the surface of the predetermined material 2 shown in Figure 4. In this regard, the inventors conducted an experiment to confirm the change in the contact angle (wettability) of the predetermined material 2. The results are shown in the graph in Figure 6.

[0043] As shown in Figure 6, in the case of polyethylene terephthalate (PET) that has only been subjected to plasma treatment, the contact angle (wettability) of the specified material 2 is initially low, but from the first day onwards, the contact angle (wettability) gradually increases. On the other hand, as explained above, in the case of polyethylene terephthalate (PET) that has been combined (reacted) with reagent 3, the contact angle (wettability) of the specified material 2 remains low for 60 days. Therefore, from the results shown in Figure 6, it was found that in the case of polyethylene terephthalate (PET) that has been combined (reacted) with reagent 3 as explained above, the hydrophilic effect can be sustained, similar to the case of polyethylene terephthalate (PET) that has been subjected to plasma treatment and hard coating treatment as shown in Figure 2.

[0044] Therefore, according to the hydrophilization method of this embodiment described above, the hydrophilic effect can be maintained.

[0045] Furthermore, according to this embodiment, when the reagent 3 is combined with the predetermined material 2 on which the hydrophilic group 2a is formed, the reagent 3 is hydrolyzed before being combined, so that when dehydration condensation is performed, the reagent 3 can be reliably bonded to the hydrophilic group 2a.

[0046] <Description of Modifications> It should be noted that the shapes and the like shown in this embodiment are merely examples, and various modifications and changes are possible within the scope of the gist of the present invention as set forth in the claims. For example, in this embodiment, polyethylene terephthalate (PET) is used as an example of the predetermined material 2, but the predetermined material is not limited to this, and any material may be used.

[0047] Furthermore, in this embodiment, 2-methacryloyloxyethyl phosphorylcholine is exemplified as the reagent 3, but the present invention is not limited to this and any reagent may be used. [Explanation of symbols]

[0048] 1. Vacuum plasma device 2. Prescribed materials 2a Hydrophilic group 2b Gap 3. Reagents

Claims

1. When forming side chains on the surface of polyethylene terephthalate, a step of modifying the surface of the polyethylene terephthalate by performing a plasma treatment on the surface of the polyethylene terephthalate to form hydrophilic groups; a step of combining 2-methacryloyloxyethyl phosphorylcholine with the polyethylene terephthalate having the hydrophilic groups formed thereon and carrying out dehydration condensation, thereby forming the side chains on the surface of the polyethylene terephthalate.

2. 2. The hydrophilization method according to claim 1, wherein when combining the polyethylene terephthalate having the hydrophilic group formed thereon with the 2-methacryloyloxyethyl phosphorylcholine, the 2-methacryloyloxyethyl phosphorylcholine is hydrolyzed before being combined.

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