JPH03109439A - Modification of polymer surface - Google Patents

Abstract

PURPOSE:To accomplish improvement in the wettability and adhesivity to inorganic material of polymer surface by forming an organic silane thin film on a polymer surface followed by irradiating the thin film with active energy rays to effect grafting of the organic silane. CONSTITUTION:A thin film (pref. 0.001-10mu thick) of an organic silane (e.g. vinyl trialkoxysilane, allyl trialkoxysilane) is formed on the surface of a polymer such as polyolefin, polyester, polycarbonate or polystyrene followed by irradiating the thin film with pref. 0.5-30Mrad of active energy rays (e.g. electron beams. gamma-rays), thus accomplishing the objective modification of the polymer surface.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to grafting organic silane on the surface of a polymer by irradiation with active energy rays to improve the wettability of the polymer surface and the adhesion to inorganic materials. It is.

[Conventional technology]

Although polymers are used in large quantities, they have poor wettability with water (in the case of cement).

When obtaining composite materials with metals such as aluminum and iron, cellulose, wood boards, etc., adhesion at the interface is poor. The following methods have been taken to improve these points. First, corona discharge treatment is a method that is carried out indirectly. This method aims to improve wettability by forming hydrophilic groups such as hydroxyl groups, carbonyl groups, and carboxyl groups on the polymer surface by corona discharge treatment, and is often used because it is simple. However, this method has the disadvantage that the adhesiveness with the inorganic material is insufficient and the adhesive performance at the interface gradually deteriorates. Another method is to use a silane coupling agent. A silane coupling agent is generally a substance represented by the formula RSi (OR) 3, where R is a hydrophobic functional group such as an alkyl group or an epoxy group, and has an affinity with a polymer. O
It is believed that the alkoxy group represented by R is hydrolyzed by moisture on the surface of the inorganic material in the air to generate a silanol group, which exhibits adhesiveness to the inorganic material. As a specific treatment method, a dilute solution of a silane coupling agent is applied thinly to the polymer surface to bond it to the inorganic material, but it is difficult for the silane coupling agent to form a uniform film on the surface. Moreover, it takes a long time to obtain a sufficient adhesive effect. In order to shorten this time, it is necessary to perform the bonding process at a high temperature of 200° C. or higher, and it is extremely difficult to shorten the bonding time because the polymer deforms or melts at this time.

As a surface modification method using active energy rays, the polymer is first irradiated with active energy rays to form active species such as radicals and peroxides on the polymer surface, and then polymerizable substances such as methyl methacrylate and acrylamide are added to the polymer surface. There is a pre-irradiation method in which monomers are brought into contact and thermally polymerized (adhesion, 1987, 423~, macron+ole
cules, 1986.1804~). However, this method has the disadvantage that it requires two steps: irradiation with active energy rays and thermal polymerization, and the required irradiation dose is large due to poor radical efficiency, leading to deterioration of the polymer. Furthermore, a method for improving surface wettability by kneading a polyfunctional monomer with a polymer in advance and then irradiating it with active energy rays has been disclosed (Japanese Unexamined Patent Application Publication No. 1988-60
-101124). However, this method also consists of two steps and is not necessarily easy; it requires a temperature of 120°C or higher to transfer the silane compound to the polymer surface during adhesion, and the amount of polyfunctional monomer used is relatively large. be. Furthermore, in this method, it is difficult to irradiate thick polymers such as molded bodies. Particularly in this case, the amount of organic silane used is large.

There are no reports of grafting organic silane onto only the polymer surface by irradiating it with active energy rays to improve wettability and adhesion to inorganic materials.

[Problem to be Solved by the Invention 1] As a result of repeated research to improve the above-mentioned drawbacks, the present inventors have succeeded in grafting organic silane onto a polymer by irradiating it with active energy rays, thereby improving wettability and adhesiveness compared to conventional methods. We have established a method for modifying polymers that has excellent adhesion properties and has an adhesive effect at lower temperatures than conventional methods.

[Means for Solving the Problems J] The present invention was made for the purpose of improving the surface wettability of a polymer and the adhesion to inorganic materials. The polymer used in the present invention is polyolefin (ethylene ,
Examples include, but are not limited to, polyesters (polyethylene terephthalate, polybutylene terephthalate, etc.), polycarbonates, polystyrene, etc.

Examples of the shape of the polymer at this time include, but are not limited to, films, sheets, molded bodies, and powders.

Methods for forming the organic silane thin film include, but are not limited to, brush coating, spraying, flow coating, dipping, electrostatic coating, and roller coating.

Examples of organic silanes include vinyltrialkoxysilane, allyltrialkoxysilane, diallyldialkoxysilane, (meth)acryloxypropyltriackoxysilane, glycidyloxypropyltrialkoxysilane, and 3-mercaptopropyltrimethoxysilane. This is not the case.

The amount of organic silane is 0 per 1 rf of surface area of the polymer.
．． 0001 to 1 log, preferably 0.000
It is 5-5 grams. The thickness of the organic silane layer at this time is preferably between 0°001 and 10 μm.

The organic silane may be used alone, or may be diluted with a solvent that is inert to alkoxysilanes having unsaturated bonds. Examples of dilutable solvents include, but are not limited to, hydrocarbons (cyclohexane, octane, toluene, etc.), ethers (dioxane, n-propyl ether, etc.), and esters (ethyl acetate, butyl acetate, etc.). .

In addition, there is no particular restriction on the type of active energy ray (e.g., electron beam, γ-ray, etc. are effective.The irradiation dose is 0.1~
In the range of 50 Mrad, preferably 0.5 to 30 Mrad
It is.

The temperature during active energy ray irradiation is preferably around room temperature, but is not limited to that.

Incidentally, it is preferable that the active energy ray irradiation is carried out in an inert atmosphere, but this does not necessarily have to be strict.

〔Example〕

The polymer modification method of the present invention is particularly effective in improving the wettability and adhesion of the polymer surface, and this case will be explained below.

During the implementation, the electron beam irradiation machine was manufactured by ESI (acceleration voltage 16
5KeV) was used.

The wettability test method was based on JIS K-6768.

As an adhesion test method, each sample film cut to 15 mm x 150 mm and aluminum foil were stacked on top of each other with an overlap of 50++ meters, and heated at 100°C for 10 minutes.
kg/crr? Press for 15 minutes under the following conditions.

Put the press piece on a tensile tester, and set the grip interval to 10cm.
It is pulled at a speed of 1 cm/min, and the maximum load is taken as the peel strength.

Example 1 High-density polyethylene (HDPE) (thickness 20μ, area 2
Using Percoater #4, a 5% octane solution of allyltriethoxysilane (TEAS) as an organic silane compound was applied to a film thickness of 2.0 μm (0.1 μm as an organic silane) using Percoater #4, and air-dried for 5 minutes. After that, an electron beam of 5.OMrad was irradiated.

Examples 2 to 3 The irradiation dose was 1.0.10. The same procedure as in Example 1 was performed except for using OMrad.

Examples 4 to 5 Octane solutions of organosilane were prepared at 25% by weight and 0.0% by weight, respectively.
5% by weight, film thickness 0.5μ as organic silane, 0.0
The coating was carried out in the same manner as in Example 1 except that the coating was applied at a thickness of 1μ.

Examples 6 to 8 Vinyltrimethoxysilane (VTMS
), diallyldimethoxysilane (DADMS), methacryloxypropyltrimethoxysilane (APTMS)
), and the rest was carried out in the same manner as in Example 1.

Examples 9 to 10 The same procedure as in Example 1 was carried out except that the HDPH thickness was 300 u, 2.0 CO+ binding, etc.

Example 11915 The polymer used was low density polyethylene (LDPE) (
100μ), polypropylene (pp) (s.

μ), polyester (PET) (100μ), ethylene-propylene block copolymer (HIPP) (60μ)
The same procedure as in Example 1 was conducted except that polycarbonate (PC) (100μ) was used.

The surface tension measurement results are shown in Table 1.

In the example, the difference in surface tension before and after irradiation was 2 to 9 dy.
ne/cm increased, and an improvement in wettability was confirmed, but in the comparative example, there was no change.

(Hereinafter, blank space) Here, an adhesion test was conducted for each film having good wettability, Examples 1, 11, 12, 13, and 14. The results are shown in Table 2.

The peel strength of each untreated sample film used as a comparative example in Table 2 is a value close to O.

In the Examples, each sample had the peel strength shown in Table 2, but in the Comparative Examples, no adhesiveness was observed at all.

[Effects of the Invention] The polymer modification method according to the present invention has great potential for applications such as lamination with metal foil, asbestos substitute materials, and printable films. Moreover, it is a very effective modification method that can be applied to surface modification of various polymer molded bodies.

Claims (1)

[Claims] A method for modifying the surface of a polymer, which comprises forming a thin film of organic silane on the surface of the polymer and irradiating it with active energy rays.