JPH0721072B2 - Surface modification method for polyolefin resin - Google Patents

Description

TECHNICAL FIELD The present invention relates to a surface modification method for a polyolefin resin.

[Prior Art] Polyolefin resins such as polyethylene and polypropylene generally have many excellent properties such as high strength and light weight, and are used as structural materials in many applications such as automobile parts.

However, the surface of the polyolefin resin is inactive and has a large contact angle with respect to water droplets, and therefore has excellent water repellent property and poor wettability. Also, the adhesiveness is extremely poor. Therefore, there are drawbacks such that it is difficult to apply the coating to the surface, the coating is not adhered and is easily peeled off, and it is difficult to form a composite material by adhering it to another material.

Therefore, it is known to activate plasma radiation as a means for improving the wettability of the surface of the polyolefin resin and improving the adhesion of the coating film. Further, for the purpose of improving the adhesiveness, for example, a method of applying an unsaturated epoxide compound and then performing a plasma treatment (Japanese Patent Laid-Open No. 62-45634) is known.

[Problems to be Solved by the Invention] However, the effect of modifying the polyolefin resin by the conventional plasma treatment is not sufficient, and in particular, the technique described in JP-A-62-45634, which measures the modification of the adhesiveness, is filamentous. Alternatively, the tape-shaped polyolefin resin is modified, and for example, a plate-shaped structural material has not been sufficiently modified.

The present invention has been made in view of such circumstances, and has improved surface properties so as to have sufficient wettability and adhesiveness irrespective of the shape of the polyolefin resin product, and therefore is used for many applications. The present invention provides a possible method for surface treatment of a polyolefin resin.

[Means for Solving the Problems] A first means of the method for surface-treating a polyolefin resin according to the present invention for solving the above-mentioned problems is to plasma-treat the surface of a polyolefin resin with alcohol vapor, and then perform steam plasma treatment. It is characterized by processing. The second means is characterized in that alcohol is applied to the surface of the polyolefin resin, plasma treatment is performed, and then steam plasma treatment is performed.

Alcohols used in the present invention include monohydric alcohols such as methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol and amyl alcohol, ethylene glycol, propylene glycol, glycerin, pentaerythritol and glucose, sucrose, starch and the like. Other polyhydric alcohols are generally referred to as alcohols, and among these, it is preferable to use polyhydric alcohols having a large amount of hydroxyl groups such as ethylene glycol, glycerin and pentaerythritol.

Further, the plasma treatment uses a so-called low temperature plasma treatment method in which the inside of the reaction vessel is made into a vacuum state to turn steam and alcohol vapor into plasma in consideration of the heat resistance of the polyolefin resin.

[Operation] By the plasma treatment, hydroxyl groups in alcohol adhere to the surface of polyolefin resin to improve wettability and adhesiveness.

By selecting and using alcohols having different hydrocarbon chains, the ratio of hydrophobicity and hydrophilicity on the surface of the polyolefin resin is adjusted.

EXAMPLES Next, the present invention will be described based on examples shown in the drawings.

FIG. 1 shows an embodiment of a surface treatment apparatus 2 used for treating the surface of an elongated sample plate 1 according to the first invention, in which a plasma reaction container 3 is a cylindrical sample below. It is made of heat-resistant glass having an installation portion 4 and a plasma generation portion 5 that bulges outwardly upward, and its lower end open surface is airtightly placed on a base 7 via an O-ring 6. Then, the cylindrical electrode 8 made of copper is formed on the outer peripheral surface of the sample setting part 4.
Are installed around. In addition, the base 7 has the upper surface as the installation portion 7a of the sample plate 1, and the gas introduction pipe 10 is provided on the top wall 9 of the plasma generation unit 5.
In addition, a gas discharge pipe 11 connected to the vacuum pump is connected.

In addition, reference numerals 12, 13, and 14 in the drawing denote a gas introduction pipe 10 and a gas discharge pipe 1.
1, an on-off valve provided in the atmosphere introduction pipe 15, 16 a harmonic power source, 17 its regulator, and 18 a manometer.

Then, in order to perform processing using the surface treatment apparatus 1 having such a configuration, first, the sample plate 1 is sufficiently washed in advance with a cleaning agent such as hexane, and dried by a desiccator or the like to remove the plasma reaction container 3 The sample is set up in the center of the sample setting unit 4.

Next, with the on-off valve 12 of the gas inlet pipe 10 closed, the gas outlet pipe
The on-off valve 13 of 11 is opened and exhausted by a vacuum pump (not shown) to bring the inside of the plasma reaction vessel 3 to a vacuum state of 0.1 Torr or less. Next, the on-off valve 13 is closed and the on-off valve 12 is opened to introduce the gas introduction pipe.
Introduce the vaporized alcohol from 10 to bring the inside of the plasma reaction vessel 3 to a predetermined gas pressure (0.1 to 1 Torr).
Plasma treatment is performed at a frequency of 13.65MHz and an output of 40w for about 60 seconds. Then, the open / close valve 14 of the atmosphere introducing pipe 15 is opened to bring the inside of the plasma reaction vessel 3 to atmospheric pressure, and the sample plate 1 is taken out. After vacuum-drying this in a desiccator, it is housed again in the sample setting part 4 of the plasma reaction vessel 3 and the inside of the plasma reaction vessel 3 is brought to a vacuum state of 0.1 Torr or less in the same manner as described above. The inside of the plasma reaction vessel 3 is brought to a predetermined gas pressure (0.1 to 1 Torr) by introducing water vapor, and 1 to 60
The surface treatment is completed by performing plasma treatment at a frequency of 13.65 MHz and an output of 40 w for about a second.

The second invention can also be carried out by using the same apparatus as the first invention, and the sample plate 1 coated with alcohols on the surface is coated with the coating surface 1a as the upper surface as shown in FIG. Then, the sample is placed on the placing part 7a, the pressure is reduced in the same manner as in the first invention, and the steam plasma treatment is performed. At this time, in the case of using alcohols which are not easily vaporized such as amyl alcohol and pentaerythritol, which are polyhydric alcohols having a relatively large molecular weight, an aqueous solution of alcohols is applied to the sample plate 1 and the plasma reaction container 3 is depressurized. Then, when the steam plasma treatment is performed by the steam generated by vaporizing the water, the alcohols remaining on the coating surface 1a react and adhere to the surface of the sample plate 1 together with the steam.

Next, the sample plate 1 is once taken out from the plasma reaction container 3, washed with water, dried using a desiccator or the like, and further subjected to steam plasma treatment in the same manner as in the first invention.

Next, the results of the test on the surface wettability and the adhesiveness of the control product made of the polypropylene resin plate material treated according to the present invention and the polyethylene and polypropylene resin plate material not subjected to any surface treatment such as plasma treatment The invention of 1 is shown in Table-I, and the invention of 2 is shown in Table-II.

In the first plasma treatment in the first invention, vapor of glycerin was used, and in the first plasma treatment in the second invention, an aqueous solution of pentaerythritol was applied to the sample plate and plasma treated for 60 seconds, respectively, and then 30
A steam plasma treatment was performed for one second. In addition, the wettability of the treated surface is evaluated by the contact angle obtained by a contact angle measuring device for each sample plate by the standing method of water droplets, and further, the adhesiveness is obtained by mixing a pair of sample plates of the present invention and a control product with an epoxy resin. A resin (trade name: Three Bond 2001) and a curing agent (trade name: Three Bond 2005) were adhered to each other and evaluated by the tensile strength (Kg / cm ² ) measured by a Shopper type tensile tester.

According to the results shown in Table-I and Table-II, the product of the present invention has an extremely small contact angle and a very large tensile strength as compared with the conventional control product which is not surface-treated. Therefore, it was demonstrated that the surface-treated polyolefin resin of the present invention has remarkably excellent wettability and adhesiveness. Particularly, in the tensile test in the first invention, the sample plates showed such adhesiveness that the sample plates were broken without being separated from each other at their adhesive surfaces.

In addition, even when it carried out similarly to the said Example using alcohol different from the said Example, the substantially same test result as said Table-I and Table-II was obtained.

[Advantages of the Invention] According to the present invention having the above-described configuration, the wettability and adhesiveness of the polyolefin resin can be significantly improved, so that good coating can be applied to the surface, or other It is possible to firmly bond with structural materials, and
By selectively using alcohols with different hydrocarbon chains, it is possible to freely adjust the ratio of hydrophobicity and hydrophilicity on the surface, and many composite members and members that require painting, etc. The new or improved product of

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of a surface treatment apparatus for carrying out the present invention, and FIG. 2 is a schematic view showing a part of another embodiment of the surface treatment apparatus.

Claims (2)

[Claims] 1. A method of modifying the surface of a polyolefin resin, which comprises subjecting the surface of the polyolefin resin to plasma treatment with alcohol vapor and then subjecting it to steam plasma treatment. 2. A method for modifying the surface of a polyolefin, which comprises coating alcohol on the surface of a polyolefin resin, plasma-treating the same, and then steam plasma-treating.