JPS6038441A - Dyeing of surface of polymeric material - Google Patents

Abstract

PURPOSE:To color a polymeric material clearly without detriment to its transparency, by graft-polymerizing a hydrophilic vinyl monomer on the surface of the material by a specified manner, and dyeing the treated material with a basic dye. CONSTITUTION:The surface of a polymeric material (e.g., polyethylene film) is treated with corona discharge in air (applied energy <=10 joule/cm<2>). A hydrophilic vinyl monomer [e.g., (meth)acrylic acid (salt) or vinylsulfonic acid (salt)] is contacted with the surface of the material in an inert gas atmosphere in the presence of a reducing agent (redox initiator system, e.g., sodium hydrogen metalsulfite/ferrous sulfate) to effect graft polymerization. The surface of the treated polymeric material is colored by coating or spraying it with an aqueous solution of a basic dye.

Description

Detailed Description of the Invention In more detail, the surface of a polymer material is subjected to a corona discharge treatment in the atmosphere, and then a hydrophilic vinyl monomer containing an anionic group capable of radical polymerization in an inert gas atmosphere is prepared. The present invention relates to a method of dyeing the polymer material by bringing one or more of them into contact with each other in the presence of a reducing agent, and then contacting the surface of the polymer material with a solution of a basic dye.

Since polymeric materials have good moldability, they can be easily formed into films or sheets. Usually, inorganic or organic pigments are used to color such polymeric materials, but the method of coloring polymeric materials using such pigments only has a negative effect on the moldability of the polymeric material. Furthermore, problems arise in terms of dispersibility in polymeric materials when pigments are mixed, and even in terms of physical properties, which limits the coloring density. In particular, when using polymeric materials that take advantage of their transparency in the form of films or sheets, it has been difficult to achieve high-density coloring.

The present inventors have researched methods for coloring such polymeric materials, especially those in the form of films or sheets that are expected to be transparent. They discovered a method and led to the present invention.

That is, the present invention is capable of radical polymerization in an inert gas atmosphere after applying energy of 10 joules/cm or less to the surface of a polymer material in advance by corona discharge treatment in the atmosphere. The polymer material is dyed by contacting one or more hydrophilic vinyl monomers containing anionic groups in the presence of a reducing agent, and then contacting the polymer material with a basic dye for dyeing. The present invention provides a method for dyeing the surface of molecular materials.

BACKGROUND ART Conventionally, methods have been proposed in which the surface of a polymeric material is treated in advance by various methods before graft polymerizing a radically polymerizable vinyl monomer onto the surface of the polymeric material (for example, JP-A-52-98011).

However, such treatment methods that have been proposed in the past, such as glow discharge treatment and radiation irradiation treatment, require specific vacuum conditions, are effective only under limited conditions, and are sensitive to the properties of polymer materials. The reality is that the method of implementation is not necessarily foolproof.

Further, in the treatment methods proposed so far, industrial use is often restricted due to their effectiveness and economical reasons, and it is difficult to call them practical methods.

As a result of various studies, the present inventors have found that the present inventors have developed a method for treating polymeric materials using a corona discharge treatment method, which has been considered to cause particular thermal damage to polymeric materials as a conventional surface treatment method for polymeric materials. One or more hydrophilic vinyl monomers containing radically polymerizable anionic groups are applied to the surface of the polymeric material in an inert gas atmosphere by applying energy of 10 units/cm or less to the surface of the polymer material. When the hydrophilic vinyl monomer is brought into contact with a reducing agent that forms a redox catalyst, the hydrophilic vinyl monomer can be uniformly graft-polymerized even at room temperature, and then the surface of the polymer material can be easily colored by bringing a basic dye into contact with it. It was discovered that a surface-colored polymeric material with good sunlight fastness could be obtained.

That is, in the present invention, energy of 10 Joules or less is applied to the surface of a polymeric material by corona discharge treatment in advance in the atmosphere, and the surface of the polymeric material contains anionic groups capable of radical polymerization in an inert gas atmosphere. A hydrophilic vinyl monomer or two or more types of vinyl monomers are brought into contact with each other at room temperature to 100°C or less in the presence of a reducing agent, and then the polymer material is brought into contact with a basic dye and dyed. achieved.

The polymeric material used in the present invention may be any material as long as it can generate beluoxide, which can be graft-polymerized by corona discharge treatment in the atmosphere, on the surface of the polymeric material. For example, low density polyethylene, high density polyethylene, ethylene-vinyl acetate copolymer, ethylene-acrylate copolymer, polypropylene, polypropylene copolymer.

polyvinyl chloride, polyvinylidene chloride, polystyrene,
Specific examples of these materials include polybutadiene, etc., and those in the form of films, sheet-like fabrics, etc., and those having an appropriate length that are movable are preferably used.

For the corona discharge treatment of the present invention, a continuous treatment device consisting of an electrode and a treatment roller, which is normally used industrially for imparting printability, is used.

Optimal processing conditions for corona discharge vary depending on material type, thickness, and processing speed, but the applied energy should be approximately 10 joules or less.

If the supplied energy is less than 1 Joule/Cm'', the coloring density will be insufficient, which is undesirable.In addition, if high energy is applied, the surface of the polymeric material will become rough, and if it is in the form of a film, the mechanical strength of the material will deteriorate. This is undesirable as it may cause deterioration or deformation of the material or the formation of pinholes.

Examples of the hydrophilic vinyl monomer containing a radically polymerizable anionic group used in the present invention include acrylic acid, methacrylic acid, and itacon+q'')-.

Maleic acid or those having a carboxyl group such as their potassium salts, sodium salts, and ammonium salts, vinylsulfonic acid, methallylsulfonic acid.

Sulfonic acids such as allylsulfonic acid, acryloyloxyethylsulfonic acid, methacryloyloxypropylsulfonic acid, styrenesulfonic acid, vinylbenzylsulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, or their potassium salts, sodium salts, and ammonium salts. Examples include those having a phosphoric acid group such as 2-acryloyloxyethyl acid phosphate and 2-methacryloyloxyethyl anrad phosphate.

In the present invention, the graft polymerization of the hydrophilic monomer is initiated by decomposing peroxide generated on the surface of the polymeric material by corona discharge treatment using a reducing agent to generate radicals.

The reducing agent used is not particularly limited as long as it is used as a redox initiator, but the polymerization reaction may be easily affected by impurities such as when a small amount of monomer is applied to the surface of the polymer material. If the reaction is carried out in the same state, it is desirable to use a slightly excessive amount of the highly effective reducing agent. For example, when using a reducing agent that combines sodium meta-acid sulfite and ferrous sulfate, 0.5 to 20 mmol of sodium meta-acid sulfite and 2
x 10-' to 8 x 10-2 mmol of sulfur-? It is desirable to add ferrous iron.

In the present invention, the grafting reaction of the hydrophilic vinyl monomer onto the surface of the polymeric material is a redox-based reaction at room temperature, and the process is sufficient even if the material used has a low softening temperature. have Furthermore, since the hydrophilic vinyl monomer can be used in an aqueous solution with a concentration of 1 to 20 wt%, this method is very advantageous in terms of handling and economy.

After forming a uniform graft polymer layer of the hydrophilic vinyl monomer by treating the surface of the polymeric material of the present invention, the surface of the polymeric material is coated with a basic dye in a water bath by dipping, spraying, or coating. The present invention is achieved by dyeing by contacting.

As the basic dye used in the present invention, general basic dyes and cationic dyes classified in the Dye Handbook (edited by the Organic Synthetic Chemistry Association, Maruzen Publishing) can be used. These dyes are used as a solution with a concentration ranging from 0.1 wt% to 10 wt%, and the pH of the dye solution is preferably adjusted to 2 to 7 using formic acid, acetic acid, sulfuric acid, or the like. The dyeing temperature of such a polymeric material can be carried out at a temperature below the deformation temperature of the polymeric material, usually in the range of 20°C to 80°C.

The present invention makes it possible to obtain vividly colored products with excellent transparency in polymeric materials, particularly films and sheets, and can be used as an excellent coloring method for packaging materials.

It can be widely used in fields such as agricultural films and molding materials.

EXAMPLES The present invention will be explained in more detail with reference to examples below, but the present invention is not limited to these examples.

Examples 1 to 6 Low density polyethylene film (density i0.925# width 25
cm, thickness 10 μm) was subjected to corona discharge treatment without pretreatment. The corona discharge machine is manufactured by Kasuga Denki (transmitter:)i
FSS-101, frequency: Proceed to 30.

Output voltage: 54 KV maximum, output voltage I KW
, electrode shape: knife-like length 30 cm) was used.

The corona discharge treatment conditions are such that the gap between the electrode and the treatment roll is [1
91III, collector current 18 to 3 A in the atmosphere,
Processing speed 0.75 m/min ~2 Tn7/rni
Continuous processing was performed at a speed of n. The amount of energy applied to the film is as shown in Table-1. The film treated with corona discharge was introduced into a nitrogen-sealed graft polymerization chamber, and a 15 wt% aqueous solution of sodium styrene sulfonate was added.
2 mmol of sodium metaacid sulfite as a reducing agent,
An aqueous monomer solution containing 1.4 x 10'' mmol of ferrous sulfate was applied.

At the same time as the aqueous vinyl monomer solution was applied, a net-like protective film (50 μm thick, 1 gap, 1.5111 mm, made of vinyl chloride resin) was sandwiched and wound up, and left as it was at room temperature for 4 hours.

Next, the protective film was peeled off from the low-density polyethylene film, taken out into water, and washed with water to obtain a surface-grafted film.

The raw material low-density polyethylene film had a contact angle with water of 80°, whereas the surface-grafted film had a small contact angle with water, as shown in Table 1.

Furthermore, a 0.5 wt aqueous solution of Kanalon Glue 50LH and Catelon Yellow T-'RLH (made by Moffl Tsuchiya Chemical Co., Ltd.) as basic dyes was prepared to pJ (4.0), and the grafted film was placed in the solution at 40°C. The films were taken out and washed with water to obtain transparent and vividly colored films.The light resistance of these films was measured using a xenon arc fade meter, and it was found to be 5th grade on the JIS Bushi Blue Scale. It showed light resistance.

Comparative Example 1 The low-density polyethylene films used in Examples 1 to 6 were not subjected to corona discharge treatment, and all other films were treated according to Examples 1 to 6, but the films could not be dyed.

Comparative Example 2 The low density polyethylene film used in Examples 1 to 6 was processed at a collector current of 5 A and a processing speed of 125 l/41 n.
Corona discharge treatment was performed. Although the energy applied to the film in this case was 20 Jl/cmt, the film was deformed and stable processing could not be performed.

Examples 7-8 Ethylene-
Vinyl acetate copolymer film (vinyl acetate content 15 q
, 25 cm inside, 60 μm thick) and a vinyl chloride resin film (hard FF film, It] 25 cm).

The same corona discharge treatment was carried out using a thin film (thickness: 60 μm). The energy applied to the film was 2.5 joules/(
It was Jl 2.

Next, after treatment with the same aqueous solution of sodium styrene sulfonate-reducing agent as in Example 4, pl (4.0 to 4.3 0 Each sample was immersed in a .5-inch water bath and dyed at 40°C to 45°C for 60 minutes.The results are shown in Table 2.

When the light resistance of the colored film was measured using a xenon arc fade melter, it showed a light resistance of JIS Bushi Blue Scale to Class 4.

Examples 9-10 In place of the vinyl monomer used in Example 4, 2-
All procedures were carried out according to Example 4 except that acrylamide-2-methylpropanesulfonic acid and acrylic f-form were used.

The vinyl monomer was used as a water bath solution, and the reducing agent was dissolved therein. The obtained film had good wettability against water, and the contact angle against water was as shown in Table 3. Further implementation? It was stained with the same basic dye as lJ4. After washing with water after dyeing, a transparent and clearly colored film was obtained.

In addition, when the light resistance of the colored film was examined using a xenon arc fade meter, it was found that the JlSlS blue scale ~
It exhibited light resistance of class 5.

Claims (1)

[Claims] After applying energy of 10 Joules/cIit or less to the surface of the polymeric material in advance in the atmosphere by corona discharge treatment, a type of hydrophilic vinyl monomer containing an anionic group capable of radical polymerization in an inert gas atmosphere or 1. A method for dyeing the surface of a polymeric material, which comprises bringing two or more types into contact with each other in the presence of a reducing agent, and then staining the polymeric material with a basic dye.