JPS583486B2 - Method for producing modified ethylene-ethyl acrylate copolymer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a modified ethylene-ethyl acrylate copolymer (hereinafter abbreviated as EEA).
The present invention relates to a method for producing modified EEA in which grafting occurs substantially uniformly during graft polymerization of unsaturated carboxylic acids or their anhydrides.

Although EEA has excellent chemical and physical properties, its use is severely restricted due to its lack of adhesion to inorganic materials such as glass and metal, printability, and dyeability.

For example, it is known that it is effective to graft unsaturated carboxylic acids or their anhydrides mainly to improve adhesion to inorganic materials such as glass and metals.

Generally, such grafting methods include (1) activating EEA with peroxide in a solvent or reacting polar monomers in the presence of peroxide (hereinafter referred to as
(2) A method in which EEA is brought into a molten state and reacted with a polar monomer in the coexistence of peroxide (hereinafter referred to as a melt method) are known.

Among these methods, the solution method allows the grafting to occur uniformly, so a uniform product can be obtained, but on the other hand, it requires separation of the polymer and solvent, a drying process, and in some cases, a solvent purification process, which requires fairly large-scale equipment and is extremely expensive. It requires a large amount of money and is impractical.

On the other hand, the melt method does not require a solvent and can be easily carried out, for example, in a place equipped with a conventional extruder, and is therefore economically very advantageous.

However, in the conventional melting method, grafting occurs unevenly,
It was difficult to maintain product uniformity.

The cause of this is that organic peroxides that are solid at room temperature and are conventionally used as graft polymerization initiators, such as benzoyl peroxide, dicumyl peroxide, lauroyl peroxide, etc., are mixed on the surface of EEA pellets or powder before melt-kneading. This is because graft polymerization was carried out by attaching it to the substrate.

Therefore, when using powdered EEA, the uniformity is somewhat improved compared to when using pellets, but it is not sufficient.

Furthermore, when powder is used, a powdering process is required, which is economically disadvantageous due to the process.

As described above, in the past, grafting occurred unevenly in the melting method, and when producing a film from the obtained product, many spots or holes were formed on the spots, which often caused problems in film production. The drawback was that it was difficult to do.

Additionally, when grafting homopolymerizable unsaturated carboxylic acids, the product of the melt process is
It has the disadvantage of inferior adhesion to inorganic materials compared to products produced by solution methods.

The object of the present invention is to provide a method for producing modified EEA that does not have the above-mentioned drawbacks.

That is, when graft polymerizing unsaturated carboxylic acids or their anhydrides to EEA in the melt method, the organic peroxide is uniformly dispersed in the EEA, so that the graft polymerization occurs uniformly. The purpose is to

Therefore, the method for producing modified EEA according to the present invention is based on BE
In the method for producing a modified EEA in which A is in a molten state and an unsaturated carboxylic acid or its anhydride is grafted onto the EEA in the presence of an organic oxide, the temperature at which the organic peroxide is in a liquid state and does not substantially decompose; Then, 0.001 to 2 parts by weight of the organic peroxide is added to 100 parts by weight of the EEA, mixed, and left for a certain period of time to give an E of 100 parts by weight before melt-kneading.
The method is characterized in that the liquid organic peroxide is diffused into the EA, and then the EEA mixture is kneaded at a temperature equal to or higher than the melting point of the EEA.

According to the present invention, the organic peroxide is mixed with EEA in a liquid state, and the organic peroxide is left to stand for a certain period of time to diffuse into the EEA before melt-kneading, and then graft polymerization is carried out, so that the graft polymerization occurs uniformly. become.

For this reason, the modified EEA produced by the method according to the present invention does not cause spots etc. even when made into a film, has excellent processability such as being easy to form into a film, and is evenly coated with unsaturated carboxylic acids or Since the anhydride is graft polymerized, the adhesion to inorganic materials is significantly improved compared to modified EEA produced by conventional melting methods.

The present invention will be explained in more detail.

The EEA used in the present invention is generally used in the form of pellets when an organic peroxide is added in the present invention, but it goes without saying that the EEA does not have to be in the form of pellets.

The shape and size of the pellets are not particularly specified, but the diameter is usually between 2 and 6 mm, and the length is between 2 and 6 mm.
It is 6mm.

The unsaturated carboxylic acids or anhydrides thereof used in the present invention include one or two of acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, maleic anhydride, itaconic anhydride, citraconic anhydride, etc. The above is exemplified.

The amount added is preferably 0.05 to 10% by weight, particularly preferably 0.1 to 5% by weight, based on EEA.

If the amount added is too small, the necessary adhesive performance will not be exhibited, and if the amount added is too large, no improvement in adhesion will be observed.

The organic peroxide used in the present invention is in liquid form and is mixed and diffused with the EEA at a temperature at which the organic peroxide does not substantially decompose.

Generally, it is desirable from an operational point of view that this temperature is room temperature or 100° C. or lower, and it is necessary that the organic peroxide does not substantially decompose for a certain period of time at these temperatures.

In view of these requirements, when producing at room temperature, it is preferable to select an organic peroxide whose half-life is 80 to 300°C at a temperature of 1 minute.

For example, it is preferable to use one or more of t-butyl hydroperoxide, di-t-butyl peroxide, and t-butyl peroxylaurate.

However, this does not negate the possibility of mixing and diffusing with EEA at room temperature or temperatures exceeding 100°C; in that case, select an organic peroxide that does not substantially decompose at that temperature and is in liquid form. do.

Also, select EEA that does not melt at the relevant temperature.

The amount of organic peroxide added is 0.001 to 2% by weight, particularly preferably 0.02 to 0.5% by weight, based on the EEA. This is not preferable because the degree of crosslinking and decomposition of EEA becomes significant.

In the present invention, the mixture of EEA (for example, in the form of lattice), unsaturated carboxylic acid or its anhydride, and liquid organic peroxide is generally left at room temperature for a certain period of time after addition of the organic peroxide. Afterwards, the mixture is kneaded at a temperature above the melting point of EEA, and under this condition, the unsaturated carboxylic acid or its anhydride is grafted onto the EEA.

Here, the certain period of time is the time required for the liquid organic peroxide to diffuse into the EEA pellets and be uniformly dispersed.

Therefore, for example, if the EEA pellet size is large,
Alternatively, if the amount of organic peroxide is large, it is necessary to increase the standing time after mixing.

Note that the EEA pellets that have passed this certain period of time are dry and easy to handle.

In the present invention, the method of mixing EEA pellets, unsaturated carboxylic acid or its anhydride, and liquid organic peroxide is as follows:
Various methods can be used depending on the nature of the unsaturated carboxylic acid or anhydride used.

As an example, some mixing methods for mixing at room temperature are listed below.

A. When the unsaturated carboxylic acid or its anhydride is liquid at room temperature and has high homopolymerizability (e.g. acrylic acid, meccrylic acid), combine the EEA pellets, the unsaturated carboxylic acid or its anhydride, and the organic peroxide. The mixture is mixed at room temperature and left for a certain period of time to diffuse and uniformly disperse the unsaturated carboxylic acid or its anhydride and the organic peroxide into the EEA pellets before melt-kneading.

B If the unsaturated carboxylic acid or its anhydride is solid at room temperature, has a relatively low melting point, and has low homopolymerizability (e.g. maleic anhydride, maleic acid), the unsaturated carboxylic acid or its anhydride and organic The oxide is dissolved in a small amount of solvent such as acetone, added to the EEA pellets, mixed and left for a certain period of time.

In this case, it is generally only the organic peroxide that is uniformly dispersed in the EEA pellets before melt-kneading.

However, because the unsaturated carboxylic acid or its anhydride has a low melting point, the unsaturated carboxylic acid or its anhydride is mixed with the organic peroxide at the initial stage of EEA melt mixing, when the organic peroxide is hardly decomposed. Uniformly dispersed in EEA.

C When the unsaturated carboxylic acid or its anhydride is solid at room temperature, has a relatively high melting point, and has low homopolymerizability (e.g. maleic acid, fumaric acid). The above mixture is kneaded to be uniformly dispersed in EEA and pelletized.

A liquid organic peroxide is mixed with the pellets at room temperature and left for a certain period of time to uniformly disperse the unsaturated carboxylic acid or its anhydride and the organic peroxide in the EEA pellets before melt-kneading.

Above, three types of mixing methods have been illustrated, but the most important thing is that unsaturated carboxylic acids or their anhydrides are Both the carboxylic acid, or its anhydride, and the organic peroxide are uniformly dispersed in the EEA.

Therefore, the addition of liquid organic peroxide and the subsequent leaving for a certain period of time are generally carried out at room temperature, but it may be carried out at a temperature higher than room temperature as long as the organic peroxide does not start to decompose. As mentioned above.

The EEA mixed with the unsaturated carboxylic acid or its anhydride and the organic peroxide as described above is then kneaded and grafted at a temperature equal to or higher than the melting point of the EEA.

The kneading device is not particularly specified, and for example, a conventional extruder, Banbury mixer, etc. can be used.

The kneading temperature must be higher than the melting point of EEA, especially 1
000-300°C is preferred.

Further, the kneading time may be 0.05 minutes or more, but is particularly preferably 0.3 to 10 minutes.

The product obtained by the present invention may contain various stabilizers such as antioxidants and ultraviolet absorbers, lubricants, plasticizers, carbon black, glass fiber, and other inorganic fillers as necessary. .

Next, the present invention will be explained with reference to Examples, but the present invention is not limited thereto in any way.

Further, in Examples and Comparative Examples, % indicates weight %, and parts indicate parts by weight based on 100 parts of polyolefin.

The unmodified EEA used in Examples and Comparative Examples is an ethylene-ethyl acrylate copolymer with an ethyl acrylate content of 23% and a melt index (MI) of 8.

The film manufacturability of the modified EEA obtained in the Examples and Comparative Examples was evaluated qualitatively by forming a film with a thickness of 50 μm using a T-die film forming machine, and determining the presence or absence of spots.

Adhesion was also measured at a crosshead speed of 100 mm/min for a test piece made of metal-modified EEA-metal adhesion.
The T-peel strength was measured and evaluated at a temperature of 23°C.

At this time, as the adherend metal, 5% Na 2 CO
Cathode degreasing with an aqueous solution at 3.5 V for 2 minutes. 5
A tin plate with a thickness of mm was used.

In addition, the modified EEA can be heat-pressed to a thickness of 0. Regarding the modified EEA obtained in Examples and Comparative Examples, a sheet formed into a 5 mm sheet was used, and adhesion was performed by heat press at a pressure of 5 kg/cm and a temperature of 120 ° C. or 160 ° C. for 5 minutes. Evaluate film manufacturability and adhesion,
The main manufacturing conditions are summarized in Tables 1 to 4.

Reference example I EEA pellets were heated and dissolved in xylene in a nitrogen stream,
Acrylic acid and then benzoyl peroxide dissolved in a small amount of xylene were added to this, and the mixture was reacted at 120° C. for 1 hour with stirring in a nitrogen atmosphere.

After the reaction, the polymer is precipitated and separated in excess methanol,
After thorough washing in methanol, it was dried to obtain a modified EEA uniformly grafted by a solution method.

This modified EEA was suitable for film production and showed high adhesion (Table 1).

Examples 1 to 5 Acrylic acid or methacrylic acid and various organic peroxides that are liquid at room temperature were added to EEA pellets, mixed at room temperature for 5 minutes, and then left at room temperature for a certain period of time in a sealed state.

Next, this inclusion pellet was extruded using an extruder to obtain modified EEA.

Details of the manufacturing conditions are shown in Table 1. The modified E obtained here
EA is modified EE that was uniformly grafted by a solution method.
Similar to A, it exhibited excellent film manufacturability and adhesion (Table 1).

Comparative Example 1 In Examples 1 to 5, instead of mixing at room temperature for 5 minutes, sealing the mixture, and leaving it at room temperature for a certain period of time, the mixture was mixed and then extruded using an extruder to obtain modified EEA.

Details of the manufacturing conditions are shown in Table 1.

The modified EEA obtained here was compared with Examples 1 to 5,
Film manufacturability and adhesiveness were poor (Table 1).

Comparative Examples 2-4 Various organic peroxides that are solid at room temperature dissolved in acrylic acid and a small amount of acetone were added to EEA pellets and mixed for 10-30 minutes at room temperature.

Thereafter, this mixture pellet was extruded using an extruder, and the modified E
Got EA.

Details of the manufacturing conditions are shown in Table 1. The modified E obtained here
EA was inferior in film manufacturability and adhesiveness compared to Examples 1 to 5 (Table 1).

Reference Examples 2 to 4 In Reference Example 1, EVA copolymer, polyethylene, and EP copolymer were used instead of EEA, and the other things were the same.
A uniformly grafted modified polyolefin was obtained.

Details of the manufacturing conditions are shown in Table 2.

The modified polyolefins obtained here were suitable for film production, and exhibited high adhesiveness as each polyolefin (Table 2).

Reference Examples 5 to 7 In Examples 1 to 5, pellets of EVA copolymer, polyethylene, and EP copolymer were used instead of EEAO,
A modified polyolefin was obtained in the same manner as above.

Details of the manufacturing conditions are shown in Table 2. The modified polyolefins obtained here exhibited excellent film productivity similar to the modified polyolefins uniformly grafted in Reference Examples 2 to 4 (Table 2).

Examples 9 to 13 Various organic peroxides that are liquid at room temperature and maleic anhydride dissolved in a small amount of acetone are added to EEA pellets, and 3
After mixing at room temperature for 0 minutes, the mixture was left sealed at room temperature for a certain period of time.

Next, this mixture pellet is extruded with an extruder into modified EEA.
I got it.

Details of the manufacturing conditions are shown in Table 3.

The modified EEA obtained here showed excellent film manufacturing properties and adhesive properties (Table 3).

Comparative Examples 6 to 8 Maleic anhydride dissolved in a small amount of acetone and various organic peroxides that are solid at room temperature were added to EEA pellets,
Mixed for 10-30 minutes at room temperature.

Thereafter, this mixture pellet was extruded with an extruder, and the modified B
Got EA.

Details of the manufacturing conditions are shown in Table 3.

The modified EEA obtained here was inferior in film manufacturability and adhesiveness compared to Examples 9 to 13 (Table 3).

Comparative Examples 14 to 16 In Examples 9 to 13, pellets of EVA copolymer, polyethylene, and EP copolymer were used instead of EEAO,
A modified polyolefin was obtained in the same manner.

Details of the manufacturing conditions are shown in Table 4. The modified polyolefins obtained here were suitable for film production and exhibited high adhesiveness as each polyolefin (Table 4).

Comparative Examples 9 to 11 Modified polyolefins were obtained in the same manner as in Comparative Examples 6 to 8, except that pellets of EVA copolymer, polyethylene, and EP copolymer were used instead of EEA.

Details of the manufacturing conditions are shown in Table 4. The modified polyolefins obtained here were inferior in film productivity and adhesiveness compared to Comparative Examples 14 to 16 (Table 4).

Examples 14 to 19 Liquid organic peroxide was added to EEA pellets mixed with maleic acid, fumaric acid, or maleic anhydride at room temperature, mixed for 30 minutes at room temperature, and then heated to room temperature for a certain period of time in a closed state. I left it alone.

Next, this mixture pellet is extruded with an extruder into modified EEA.
I got it.

Details of the manufacturing conditions are shown in Table 4. The modified E obtained here
EA showed excellent film manufacturability and adhesion (Table 4).

Comparative Examples 12-13 Organic peroxide, which is solid at room temperature and dissolved in a small amount of acetone, was added to EEA pellets that had been kneaded and mixed using a Malein machine or a Fumar machine, and mixed for 30 minutes at room temperature.

Then, this mixture pellet was extruded with an extruder into modified EE.
I got an A.

Details of the manufacturing conditions are shown in Table 4.

The modified EEA obtained here was inferior in film productivity and adhesiveness compared to Examples 14 and 15 (Table 4).

As explained above, the modified EE produced according to the present invention
Unlike modified EEA produced by known melting methods, A is uniformly grafted, and therefore exhibits high adhesion to inorganic materials, especially metals.

Therefore, there is an advantage that the scope of application of EEA can be significantly expanded.

Claims (1)

[Claims] 1. A modified ethylene-ethyl acrylate copolymer in which an ethylene-ethyl acrylate copolymer is melted and an unsaturated carboxylic acid or its anhydride is grafted onto the ethylene-ethyl acrylate copolymer in the presence of an organic peroxide. In the method for producing a polymer, the organic peroxide is added to 100 parts by weight of the ethylene-ethyl acrylate copolymer at a temperature where the organic peroxide is in a liquid state and is not substantially decomposed. Add 2 parts by weight, mix and leave for a certain period of time to diffuse the liquid organic peroxide into the ethylene-ethyl acrylate copolymer before melt-kneading, then,
A modified ethylene-acrylic acid copolymer characterized in that a mixture of an ethylene-acrylic acid copolymer, an unsaturated carboxylic acid or its anhydride, and an organic peroxide is kneaded at a temperature equal to or higher than the melting point of the ethylene-ethyl acrylate copolymer. Method for producing ethyl acid copolymer.