JPH0367104B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for dyeing the surface of a polymeric material. 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 materials. Furthermore, problems arise in terms of dispersibility in polymeric materials when pigments are mixed, and even physical properties, which limits the coloring density. In particular, it has been difficult to color at a high concentration when using polymer materials that take advantage of their transparency in the form of films or sheets. The present inventors have researched methods for coloring such polymeric materials, especially film-like or sheet-like polymeric materials that require transparency, and have developed a method for coloring polymeric materials that can be vividly colored without losing transparency. A coloring method was discovered, leading to the present invention. That is, after applying energy of 1 to 10 joules/cm ² to the surface of a film-like or sheet-like polymer material in advance by corona discharge treatment in the atmosphere, sulfonic acid groups capable of radical polymerization are added in an inert gas atmosphere. After applying a monomer aqueous solution in which a reducing agent is dissolved in an aqueous solution of one or more hydrophilic vinyl monomers containing The present invention provides a method for dyeing the surface of a polymeric material, which is characterized by washing with water and then dyeing with a basic dye. Conventionally, methods have been proposed in which the surface of a polymeric material is treated in advance by various methods when graft polymerizing a radically polymerizable vinyl monomer onto the surface of the polymeric material (for example,
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 this is not necessarily a satisfactory method to implement without causing damage. In addition, 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 researches, the present invention has developed a method for uniformly treating hydrophilic vinyl monomers using a corona discharge treatment method, which has been considered to cause particular thermal damage to polymer materials as a conventional surface treatment method for polymer materials. can be graft polymerized to, easily colored,
This is based on the discovery that a surface-colored polymeric material with good sunlight fastness can be obtained. The polymeric material used in the present invention may be any material that can generate a graft-polymerizable peroxide on the surface of the polymeric material by corona discharge treatment in the atmosphere. Examples include low density polyethylene, high density polyethylene, ethylene-vinyl acetate copolymer, ethylene-acrylate copolymer, polypropylene, polypropylene copolymer, polyvinyl chloride, polyvinylidene chloride, polystyrene, polybutadiene, and the like. Specifically, these are in the form of a film, a sheet-like fabric, 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 comprising 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 ² , the coloring density will be insufficient, which is not preferable. Also, when high energy is applied, the surface of the polymer material becomes rough,
In addition, in the case of a film, the mechanical strength of the material may be reduced or deformed, or pinholes may occur, which is undesirable. The hydrophilic vinyl monomer containing a radically polymerizable sulfonic acid group used in the present invention includes:
For example, vinyl sulfonic acid, methallyl sulfonic acid, allyl sulfonic acid, acryloyloxyethyl sulfonic acid, methacryloyloxypropylsulfonic acid, styrene sulfonic acid, vinylbenzyl sulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, or these Examples include those having a sulfonic acid group such as potassium salt, sodium salt, and ammonium salt. In the present invention, the graft polymerization of the hydrophilic monomer is initiated by decomposing peroxide generated on the surface of the polymer material by corona discharge treatment using a reducing agent to generate radicals. The reducing agent to be used is not particularly limited as long as it is used as a redox initiator, but the polymerization reaction may be carried out in a state where it is easily affected by impurities, such as when a small amount of monomer is applied to the surface of the polymeric material. When carrying out this method, it is desirable to use a slightly excessive amount of a highly effective reducing agent. For example, when using a reducing agent that combines sodium metaacid sulfite and ferrous sulfate, for 100 g of monomer solution,
Preferably, 0.5 to 20 mmol of sodium metaacid sulfite and 2 x 10 ^-4 to 8 x 10 ^-2 mmol of ferrous sulfate are added. The grafting reaction of the hydrophilic vinyl monomer onto the surface of the polymeric material in the present invention has the advantage that a redox-based room-temperature reaction is sufficient, and the process can be carried out satisfactorily even if the material used has a low softening temperature. Furthermore, the hydrophilic vinyl monomer is 1 to
Since an aqueous solution with a concentration of 20wt% is sufficient for use,
This is a very advantageous method in terms of handling and economy. Note that the use of a protective film is essential to prevent uneven adhesion of monomers due to the hydrophobicity of the surface of the polymeric material, and to ensure uniform surface treatment. 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 immersed in an aqueous solution of a basic dye and treated by spraying or coating. The present invention is achieved by dyeing by contacting according to a method. 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 range from 0.1wt% to 10wt%
The pH of the dye solution can be adjusted to 2 using formic acid, acetic acid or sulfuric acid.
It is desirable to adjust it to ~7. 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 highly transparent and clearly colored polymer materials, especially films and sheets, and is used as an excellent coloring method in the fields of packaging materials, agricultural films, molding materials, etc. Widely available. EXAMPLES The present invention will be explained in more detail below with reference to Examples, but the present invention is not limited to the Examples. Comparative Examples 1-2, Examples 1-4 Low density polyethylene film (density 0.925, width
(25 cm, thickness 10 μm) was subjected to corona discharge treatment without pretreatment. The corona discharge machine is manufactured by Kasuga Denki Co., Ltd. (transmitter: HFSS-101, frequency: 30kHz, output voltage:
34KV maximum, output power: 1KW, electrode shape: knife shape, length 30cm) was used. The corona discharge treatment conditions are: the gap between the electrode and the treatment roll is 0.9 mm, and the collector current is 1A ~ 1A in the atmosphere.
Continuous processing was carried out at a speed of 3A and a processing speed of 0.75 m/min to 2 m/min. The amount of energy applied to the film is shown in Table-1. The film treated with corona discharge was introduced into a graft polymerization chamber sealed with nitrogen, and monomers containing 2 mmol of sodium metaacid sulfite and 1.4 x 10 ^-3 mmol of ferrous sulfate as reducing agents were dissolved in 100 g of a 15 wt% aqueous solution of sodium styrene sulfonate. An aqueous solution was applied. A mesh protective film (thickness 50 μm, gap 1.5 mm, vinyl chloride resin net) was applied at the same time as the vinyl monomer aqueous solution was applied.
It was sandwiched and rolled 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 smaller contact angle with water, as shown in Table 1.

[Table] In addition, Cachilon Blue is used as a basic dye.
A 0.5 wt% aqueous solution of 5GLH and Cachilon Yellow T-RLH (both manufactured by Hodogaya Chemical) was prepared at pH 4.0, and the grafted film was immersed therein at 40°C for 120 minutes. The films were taken out and washed with water to obtain transparent and vividly colored films. When the light resistance of these films was measured using a xenon arc fade meter, the light resistance of the comparative example was 3rd grade and the examples were 4th to 5th grade on the JIS blue scale. Comparative Example 3 The low density polyethylene film used in Example 1 was treated under all other conditions as in Example 1 without being subjected to corona discharge treatment, but the film could not be dyed. Comparative Example 4 The low density polyethylene film used in Example 1 was treated with a collector current of 3A and a processing speed of 0.25.
Corona discharge treatment was performed at m/mis. Although the energy applied to the film in this case was 20 Joule/cm ² , the film was deformed and stable processing could not be performed. Examples 5 to 6 In place of the film used in Example 2, ethylene-vinyl acetate copolymer film (vinyl acetate content 15%, width 25 cm, thickness 60 μm) and vinyl chloride resin film (hard film, width 25 cm, thickness 60μ
The same corona discharge treatment was carried out using m). The energy applied to the film was 2.5 joules/cm ² . Next, after treatment with the same aqueous solution of sodium styrene sulfonate-reducing agent as in Example 2, basic dyes methylene blue FZ and catylone red were added.
GLH (all manufactured by Hodogaya Chemical) PH4.0-4.3 0.5
% aqueous solution 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 meter, it showed a light resistance of grade 3 to 4 on the JIS blue scale. The reason why the light resistance is slightly inferior to that of other dyes is that the light resistance of the red dye itself is inferior to that of blue or yellow dyes.

[Table] Example 7, Comparative Example 5 The same procedures as in Example 4 were carried out except that 2-acrylamido-2-methylpropanesulfonic acid and acrylic acid were used in place of the vinyl monomer used in Example 2. The vinyl monomer was used as a 10% aqueous 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. Furthermore, it was dyed with the same basic dye as in Example 4. The water-washed films after dyeing were transparent and clearly colored films.
Furthermore, when the light resistance of the colored film was examined using a xenon arcfade meter, it was found to have a light resistance of grade 3 in the comparative examples and grade 5 in the examples on the JIS blue scale. This shows that the sulfonic acid group has better light resistance than the carboxylic acid group.

[Table] Comparative Example 6 After applying the vinyl monomer aqueous solution without using the reticular protective film used in Example 1,
The same procedure as in Example 1 was carried out except that the film was wound up as it was and left to stand at room temperature for 4 hours. After dyeing, the obtained film showed a mottled pattern, and a uniform dyed state could not be obtained. This is because a reticular protective film was not used, so the vinyl monomer could not be spread uniformly on the film.
This was because the graft state of the vinyl monomer was non-uniform.

Claims (1)

[Claims] 1. After applying energy of 1 to 10 joules/cm ² to the surface of a film or sheet polymer material in advance by corona discharge treatment in the atmosphere,
A monomer aqueous solution containing a reducing agent dissolved in an aqueous solution of one or more hydrophilic vinyl monomers containing sulfonic acid groups capable of radical polymerization is applied in an inert gas atmosphere, and the surface is protected with a protective film and left at room temperature. 1. A method for dyeing the surface of a polymeric material, which comprises polymerizing the monomer at a temperature of 100° C. to 100° C., washing with water, and then dyeing with a basic dye.