JPH03290419A - Production of modified eva and composition thereof - Google Patents

Abstract

PURPOSE:To obtain the subject polymer soluble in solvent, having excellent adhesivity and useful for paint, etc., by subjecting a specific copolymer e.g. to esterification with an alpha,beta-unsaturated carboxylic acid, etc., and polymerizing a vinyl-containing compound to the product. CONSTITUTION:A partially saponified ethylene-vinyl acetate copolymer (having a molecular weight of preferably 10,000-100,000 and a saponification degree of preferably 1-60%) is subjected to esterification or ester-interchange reaction with an alpha,beta-unsaturated carboxylic acid (e.g. acrylic acid) or its ester and a vinyl-containing compound (e.g. methacrylic acid) is polymerized to the product to obtain the objective polymer. A coating resin composition containing said polymer exhibits excellent adhesivity to polar and non-polar plastic films.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a method for producing solvent-soluble modified EVA and a composition thereof, and is used as a coating material for various plastic films, sheets or other molded products, such as paints and printing inks. , modified EV useful as a resin or resin composition for coating agents
The present invention aims to provide a method for producing A and a composition thereof.

[Conventional technology]

In recent years, with the diversification of packaging containers, printing inks and various coating agents used to decorate or protect the surfaces of plastics and the like are also required to have high performance and quality.

In addition, especially for plastic films, various plastic films are sometimes laminated after printing in order to improve their functionality as packaging base materials. For example, polyester film or nylon film is often laminated with different films such as polyethylene film or polypropylene film, but when laminating these various plastic films, the printing ink and In addition to adhesion to various substrates and suitability for printing, coating agents are required to have suitability for post-processing, and such suitability is greatly influenced by the binder resin used in the printing ink.

Conventionally, a thermoplastic polyester resin has been used as a binder resin for polyester films, and a two-component reactive resin of a hydroxyl group-containing polyester resin and an isocyanate compound has been used as a binder for nylon films. Recently, printing inks using polyurethane resin as a binder resin have also come to be used for polyester films and nylon films.

On the other hand, printing inks using chlorinated polyolefin as a binder are used for polyolefin films such as polyethylene films and polypropylene films. Among these, chlorinated EVA is used as a binder for polyolefin films to improve pigment dispersibility, color development,
Although it has excellent ink suitability such as glossiness, it does not have sufficient adhesion to substrates, and is often used by adding chlorinated polypropylene or the like to compensate for shortcomings such as tackiness.

[Problem to be solved by the invention] Polyester resins and polyurethane resins have good adhesion to polar substrates such as polyester films and nylon films, but do not have sufficient adhesion to non-polar substrates such as polyolefin films. Further, the pigment dispersibility is also not good.

On the other hand, chlorinated polyolefins have good adhesion to nonpolar substrates such as polyolefin films, but do not have sufficient adhesion to polar substrates such as polyester films and nylon films.

For this reason, printing inks must be manufactured by blending different binder resins with various plastic films, which poses a problem in that manufacturing tends to be complicated. In addition, it is desirable that the printing ink used in laminating different types of plastic films as described above not only has adhesive properties to the base film but also adhesive properties to the laminate film.
At present, there is no binder resin that satisfies this requirement. Therefore, an attempt was made to blend or react these resins with different polarities to obtain a resin that satisfies the adhesion to films of both polarities (JP-A-61-9117711, JP-A-6
4-115226, JP-A-64-85227), but generally the mutual compatibility between the resins is insufficient, so phase separation tends to occur, and sufficient printability cannot be obtained in many cases.

In addition, EvA and chlorinated EVA have good wettability with pigments, so they contribute to pigment dispersibility in paints and printing inks, but they have the disadvantage of being sticky and easily causing blocking.

[Means to solve the problem]

As a result of extensive research in order to solve the above problems, the inventors discovered that α,β-unsaturated carboxylic acid or its esterified product was esterified or esterified into a partially saponified product of ethylene-vinyl acetate copolymer (EVA). After an exchange reaction, a method for producing solvent-soluble modified EVA obtained by polymerizing a vinyl group-containing compound was discovered, and a coating resin ad using this was discovered.
The present invention was completed based on the discovery that the material has sufficient adhesion to non-polar polyolefin films and polar polyester films.

Furthermore, coatings using this resin are non-tacky and solve workability problems such as blocking.

The EVA used in the present invention has a molecular weight of 5000 to 51)
l(lθ can be used, but 101100~+00
A value in the range of 000 is preferred. When the molecular weight is lower than this range, blocking tends to occur, and when the molecular weight is high, the solubility in organic solvents tends to be poor and the pigment dispersibility tends to decrease.

Partial saponification of EVA can be performed by a well-known method, and the degree of saponification can be adjusted as necessary. However, if the degree of saponification is too high, the solubility in the solvent will deteriorate, so it is desirable that the degree of saponification is in the range of 1 to 60%.

Next, the partially saponified EVA is reacted with an α,β-unsaturated carboxylic acid or its esterified product by esterification or transesterification reaction. α, β− at this time
Examples of unsaturated carboxylic acids include acrylic acid, methacrylic acid, itaconic acid, and maleic acid.

Examples of esterified products thereof include methyl esters, ethyl esters, propyl esters, butyl esters, and the like. In the esterification or transesterification reaction, the partially saponified product of EVA described above is dissolved in a single or mixed solvent such as benzene, toluene, xylene, methyl ethyl ketone, methyl isobutyl ketone, tetrahydrofuran, etc. to a concentration of 1 to 30%, and the above-mentioned A necessary amount of the α,β-unsaturated carboxylic acid or its esterified product is added, a catalyst is further added, and the reaction is carried out at, for example, 40 to 80° C. for several hours to several tens of hours.

As the catalyst, an acid catalyst is preferable, and p-1 toluenesulfonic acid, metal acetate, hydrochloric acid, etc. can be used as examples.

Subsequently, an appropriate amount of a vinyl group-containing compound is added to the resin, a radical generator is added, and the mixture is reacted at, for example, 50 to 100°C for several hours. Vinyl group compounds include acrylic acid, methacrylic acid, maleic acid, or esterified products thereof;
Examples include styrene and acrylonitrile.

Examples of the radical generator include organic peroxides such as pencil liver oxide, dibutyl peroxide, and azobisisobutyrilonitrile, and diazo compounds.

The modified EVA solution obtained as described above may be purified to remove residual monomers, catalysts, etc., if necessary, or may be made into a solid by removing the solvent. In addition, when producing paints, printing inks, etc. using the modified EVA obtained as described above, in addition to the modified EVA, chlorinated polypropylene resin, chlorinated polyethylene resin, thermal Binder resins such as plastic polyester resins and polyurethane resins can also be blended. A pigment and a solvent may be added to the above resin or resin composition, kneaded, and if necessary, a plasticizer, antiblocking agent, etc. may be added for use.

[For production]

The modified EVA of the present invention is one in which the chemical properties, morphology, etc. are changed by graft modification, and new functions are imparted to the properties of EVA. As shown below, the grafting method involves the first step of reacting partially saponified EVA with α,β-unsaturated carboxylic acid or its esterified product through esterification or transesterification reaction to introduce a vinyl group into the main chain of EVA. reaction, and a second stage reaction in which a vinyl group-containing compound is polymerized to the vinyl group to form a graft chain.

Such grafting changes the polarity of the molecular chains, making it possible to adhere to different types of plastic films, and also improves adhesion by increasing entanglement between molecular chains due to the grafted chains. considered to be a thing.

〔Example〕

The present invention will be specifically explained below with reference to Examples, but the present invention is not limited thereto.

Synthesis Example 1 320 g of toluene was added to 80 g of partially saponified EVA (vinyl acetate pigment 41%) (degree of saponification 44.6%) and dissolved.
To this were added 11.9 g of acrylic acid and 0.9 g of p-toluenesulfonic acid, and the mixture was reacted at a temperature of 60° C. for 5 hours. After adding 400 g of toluene to this, 1.2 g of benzoyl peroxide and 40 g of styrene were added and reacted at a temperature of 70° C. for 5 hours. After the reaction, toluene is distilled off to reduce the solid content to 20%.
A resin solution A was obtained.

Synthesis Example 2 320 g of toluene was added to 80 g of partially saponified EVA (vinyl acetate pigment 41%) (degree of saponification 44.6%) and dissolved.
To this was added 11.9 g of acrylic acid and 0.9 g of p-toluenesulfonic acid, and the mixture was reacted at a temperature of 60 DEG C. for 5 hours. After adding 400 g of toluene to this, 1.2 g of benzoyl peroxide and 20 g of styrene were added and reacted at a temperature of 70° C. for 5 hours. After the reaction, toluene is distilled off to reduce the solid concentration to 2.
A 0% resin solution B was obtained.

Synthesis Example 3 320 g of toluene was added to 80 g of partially saponified EVA (vinyl acetate pigment 41%) (degree of saponification 44.6%) and dissolved.
To this were added 11.9 g of acrylic acid and 0.9 g of p-toluenesulfonic acid, and the mixture was reacted at a temperature of 60° C. for 5 hours. After adding 400g of toluene to this, 1.2g of benzoyl peroxide and 40g of methyl methacrylate were added and the temperature was 70°C.
React for 5 hours. After the reaction, toluene was distilled off to obtain a resin solution C with a solid content concentration of 20%.

Synthesis Example 4 320 g of toluene was added to 80 g of partially saponified EVA (vinyl acetate pigment 41%) (saponification level 446%) and dissolved. To this, 11.9 g of acrylic acid and 0.9 g of I)-toluenesulfonic acid were added and the temperature React at 60°C for 5 hours. After adding 400g of toluene to this, 1.2g of benzoyl peroxide and 20g of methyl methacrylate were added and the temperature was 70.
React at ℃ for 5 hours. After the reaction, toluene was distilled off to obtain a resin solution with a solid content concentration of 20%.

Resin solutions A and B obtained by the above synthesis example.

An ink was prepared using the following formulation using C and D, and its adhesion to various stick films was evaluated, and the results were summarized in Example 1. 2. 3 and 4 in Table 1. The results of EVA are also shown as a comparative example.

Formula resin solution (A, B, C, D and EVA 20% solution)
125 parts Pigment (Carmine 5BN manufactured by Tokyo Ink) 20 parts Ethyl acetate 30 parts Toluene
Predetermined concentration adjustment amount Adhesiveness test The ink obtained from the above formulation was applied to polypropylene film (OPP) and polyester film (PET) using a coating rod (#Ia), and after drying for one day, cellophane tape was attached. Observe the condition of the coated surface when it is peeled off, and if 80% or more of the coating remains, mark it as ○.
Those with 50% or more remaining were shown as △, and those with more than 50% peeling off were shown as ×.

Adhesiveness After coating and drying as described above, the tackiness of the coated surface was evaluated using a touch finger at room temperature.

Table [Effects of the Invention] As explained above, when the solvent-soluble modified EVA obtained by the production method of the present invention is used as a coating resin composition for paints, inks, etc., it is effective against polar and non-polar plastic films. It is clear that coatings with good adhesion and improved tack are obtained.

Claims (2)

[Claims] (1) After esterifying or transesterifying a partially saponified ethylene/vinyl acetate copolymer (EVA) with an α,β-unsaturated carboxylic acid or an ester thereof,
Solvent-soluble modified EVA made by polymerizing vinyl group-containing compounds
A manufacturing method to obtain (2) A coating resin composition comprising the solvent-soluble modified EVA according to claim 1.