JPS5959728A - Surface modification of plastic film or sheet - Google Patents

Abstract

PURPOSE:To improve the peeling and scaling off of a formed polymer layer without detriment to the ground film, by applying a polar group-carrying monomer containing a specified polymerization initiator to the surface of a nonpolar plastic film, and polymerizing the monomer. CONSTITUTION:A composition prepared by mixing a polar groupcarrying monomer with a polymerization initiator comprising a mixture containing (i) a dialkyl peroxide and/or a peroxy ketal and (ii) a diacyl peroxide and/or a peroxy ester is applied to at least one of the surfaces of a film or sheet of a nonpolar plastic such as polyethylene or polypropylene. Then, this layer applied is polymerized by heating, whereby a polar group-carrying layer of a thickness of below 1mum is formed on at least one of the surface of the film or sheet. The amount of the polymerization initiator used is preferably 0.2-5.0pts.wt. per 100pts.wt. monomer.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a method for surface modification of non-polar plastic films or sheets such as polyethylene and polypropylene.

Adding polarity to the surface of a non-polar film or sheet is useful in improving visibility, oil resistance, and the like. Conventionally, this purpose has been achieved by oxidizing the surface of polyethylene film or sheets by electrical discharge or by using chemicals, but such oxidation methods deteriorate the underlying film or sheet. There is one drawback. Another method is to react a compound with a polar group to one part of the film or sheet, but this method lacks chemical bonding with the substrate and is easily peeled off, resulting in insufficient performance. It was difficult to demonstrate this.

The present invention aims to provide a surface modification method different from the conventional method described above, and its gist is to provide a method for modifying the surface of non-polar plastic films or sheets such as polyethylene and polypropylene. , after coating a composition comprising a monomer having a polar group containing a mixture of dialkyl peroxides 8 and/or peroxyketals and diacyl peroxides 3 and/or peroxy esters as a polymerization initiator; , a method for surface modification of a silastic film or sheet, characterized in that the above-mentioned film map is provided with a layer having a polar group having a thickness of 1 μm or less on at least one curve of the sheet by thermal polymerization. .

That is, in the third aspect of the present invention, by applying a monomer having a polar group to the surface of a film or sheet and thermally polymerizing it with a specific polymerization initiator,
A single layer of polymer having polar groups chemically strongly bonded to the surface of the substrate is provided. Since the bonding strength is high, there is no problem of the polymer layer peeling off during handling.

Therefore, the film or sheet whose surface has been modified by the method of this invention can take advantage of the feature that the inside is non-polar, and at the same time, the film or sheet that has been surface-modified by the method of the present invention can take advantage of the feature that the inside is non-polar, as well as the excellent properties imparted by the polar groups introduced into the surface. It can also take advantage of properties such as adhesiveness and oil resistance, and can be used extremely effectively in various applications that require these properties. Furthermore, by providing a single layer of polymer only on the - side, it is possible to obtain a film or sheet in which one side is non-polar and the other side is polar.
As a result, it can be used as a film or sheet whose front and back sides have completely different properties, such as a highly deformable release film or a film that has both water repellency and hydrophilicity.

Typical non-polar plastic films or sheets to be applied to this invention are polyolefins such as polyethylene, polypropylene, etc.;
ter) is 8 or less, it can be widely applied. Na8
, 2 S l) value is the value presented by Krcvclen (,
means the value calculated from the contribution value of the attraction constant of the atomic group.

The monomer having a polar group used in this invention may be one having an SP value (same meaning as above) as a homopolymer of 10 or more, and specific examples include hydroxyethyl acrylate. Acrylic acid esters having a hydroxyl group such as 1., monomers having a cal or IK xyl group such as acrylic acid or methacrylic acid, monomers having a di-I-lyl group such as acrylonitrinopemeccrylonitrile; Examples include.

As the polymerization initiator to be added to the above-mentioned motsuma, dialkyl peroxides and/or oxidants and diacyls, (-oxides B and/or oxides and/or peroxyesters) are used. The latter diacyl/N6-oxides or peroxyesters are very effective as polymerization initiators for 1-year polymers, but these compounds alone cannot be used to form films or sheets. It has poor cross-linking properties, and to avoid this drawback, dialkyl peroxides or +-oxy-11 tars are used in combination, thereby achieving both bonding properties to films or sheets and polymerization reactivity. It is.

Examples of the dialkyl peroxides used here include diacyl peroxide and E-butylcumyl peroxide, and a representative example of the -oxykecools is bis-1-butylperoxycyclohexane. can. Typical examples of diacyl peroxide a, +'i include dibenzoyl peroxide and dilauroyl peroxide;
As the sO-oxyesters, thi-butyl/
N6-oxypimarate is mentioned. of course,
``-- (without limitation, any of the various commercially available peroxides included in each category can be used.

The amount of the polymerization initiator used may be in the range of 0.2 to 5.0 parts by weight based on 100 parts by weight of the monomer. It is desirable that the proportion of the peroxide '9j mill 3 and/or the peroxy esters is such that the weight ratio of the former to the latter is within the range of 1:1 to 1:20.

In the present invention, a composition containing a monomer having two polar groups and a polymerization initiator is applied to one side of the non-polar plastic film or sheet, and then the polymerization initiator is applied. 2Aj' depending on the type, usually 6
Polymerization is carried out by heating at 0 to 180°C to form a single layer of polymer having a polar group in -.

The thickness of this layer should be 1 μnL or less; if it becomes too thick, the characteristics of the base film or Sea I-FJ+ will be impaired, so it is not preferable.

Next, examples of this invention will be described. Below is 4 parts by weight means 4 parts by weight.

Example 1 A solution prepared by mixing 100 parts of hydroxyethyl acrylate, 410.2 parts of dibenzoyl peroxa, and 1 part of dicumyl peroxide was applied to one side of a polypropylene film with a thickness of 50 μnL, and the mixture was heated at 80° C. in a nitrogen stream. After heating at 160 DEG C., polymerization was performed to form a single layer of 1 .mu.m thick polymer on the surface.

Example 2 One side of a 100 μm thick polyethylene film was coated with 100 parts of acrylic acid and 0.00 parts of 1-butylperoxypyparade.
3 parts and 2 parts of [-butylic cumyl peroxide,
It was then heated to 60 to 80°C in carbon dioxide gas, then further heated to 90°C to polymerize, and the - side was coated with 0.
．． A single layer of polymer with a thickness of 5 μm was formed.

Example 3 On one side of a butyl rubber sheet with a thickness of 500 μm, 100 parts of methacrylonitrile and 0 parts of dilauroyl peroxide were added.
．． A mixture of 3 parts of dicumyl peroxide and 2 parts of dicumyl peroxide was coated and heated at 60 to 80°C in a nitrogen stream, and further heated to 170°C to polymerize.
．． Form a single layer of polymer with a thickness of 0 μm.

Example 4 A mixture of 100 parts of methacrylic acid, 0.5 parts of dibenzoyl peroxide, and 1.0 parts of bis-E-butylperoxycyclohexane was coated on one surface of polyethylene with a thickness of 100 μm, Heat at 80°C and then further heat to 110°C to polymerize.'' - 0.5 on one side
Part mj grass polymer layer τ1-formed).

The modified surface of each film or sheet modified by the above method was adhered to a steel plate using a neorene adhesive, and the adhesive strength (K9/25 mm rl) was measured at 20°C. The results are shown in the table below. It was Σ when it came out. NaS
In Table 1, 8 indicates the results of each example, and B and (4) indicate the results when untreated.

- As is clear from the table, the modification method of the present invention can greatly improve the adhesive strength between the non-polar plastic film and the subject.

Claims (1)

[Claims] (1) At least one surface of a non-polar plastic film or sheet such as polyethylene or polypropylene is coated with dialkyl peroxides and/or peroxyketals and diacyl peroxides and/or peroxyketals as a polymerization initiator in a monomer having a polar group. 1. After coating a composition containing a mixture with peroxyesters, the film or sheet 1 is coated with a composition containing a mixture with peroxyesters and heated to polymerize.
2. A method for surface modification of plastic films and sheets, characterized by providing a layer having a polar group underneath.