JPS6325005B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a graft copolymer,
Specifically, the present invention relates to a method for producing graft copolymers with excellent physical properties by using a specific propylene polymer, treating it with ozone, and then grafting it with a vinyl monomer. Generally, propylene-based polymers such as polypropylene have poor adhesiveness, paintability, printability, etc., and various methods for modifying them have been proposed. For example, a method is known in which polypropylene is exposed to radiation, organic peroxide, or ozone and then graft polymerized with vinyl monomers. It is possible to obtain a combination (Japanese Patent Publication No. 46-4383, Japanese Patent Publication No. 8619-8619). However, even in this case, there remains the problem that the molecular weight of polypropylene decreases during ozone treatment, and although this improves secondary processability such as adhesion, it leads to a decrease in mechanical strength. There was a problem. The present inventor has conducted extensive research in order to solve the above-mentioned conventional problems and develop a material with excellent adhesiveness, paintability, etc. while maintaining sufficient mechanical strength.
As a result, the inventors discovered that the object could be achieved by using a specific ethylene-propylene block copolymer as the propylene polymer to be treated with ozone, leading to the completion of the present invention. That is, in the present invention, a propylene-based polymer is treated with ozone, and then a vinyl monomer is graft-polymerized to the obtained ozonated propylene-based polymer to produce a graft copolymer. Ethylene having a unit content of 4 to 15% by weight, an ethylene block molecular weight of 20,000 to 45,000, and a total molecular weight of 250,000 to 350,000.
The present invention provides a method for producing a graft copolymer characterized by using a propylene block copolymer. The propylene polymer used in the method of the present invention is
As mentioned above, it is an ethylene-propylene block copolymer, and its properties include an ethylene unit content of 4 to 15% by weight, preferably 7 to 12% by weight, and an ethylene block molecular weight of 20,000 to 45,000, preferably
30,000 to 40,000, and the molecular weight of the entire copolymer
250,000 to 350,000, preferably 270,000 to 290,000. If the molecular weight of the copolymer is less than 250,000, physical properties such as mechanical strength will be poor, and if it exceeds 350,000, moldability will be poor. Moreover, if the ethylene unit content in the copolymer is too small, the molecular weight decreases in the ozone treatment step will be large, which is not preferable. There are various methods for producing this ethylene-propylene block copolymer, but the most common method is to polymerize propylene and then polymerize ethylene by coordination polymerization based on a commonly known Ziegler type catalyst. obtained by. There are various methods for ozone treatment of this ethylene-propylene block copolymer.
There is no particular limitation, and in short, the above block copolymer may be activated to facilitate the subsequent grafting reaction. Specifically, this is carried out by bringing an ozone-containing gas having an ozone concentration of 15 mg/or more, preferably about 30 mg/into contact with the above-mentioned ethylene-propylene block copolymer. The processing time at this time may be determined as appropriate depending on the temperature, concentration of ozone-containing gas, etc. For example, at room temperature,
A good guideline is around 60 minutes. The form of the ethylene-propylene block copolymer to be brought into contact with the ozone-containing gas is not particularly limited, but a form with good contact efficiency is preferable. It is also effective to form a solution in which it is dissolved in. According to the method of the present invention, a vinyl monomer is graft-polymerized onto the thus obtained ozonated ethylene-propylene block copolymer. This grafting reaction can be carried out under various conditions. For example, as the polymerization method, bulk polymerization or suspension polymerization is preferred, but semi-emulsion polymerization may also be used. The temperature during the polymerization reaction may be determined depending on various conditions such as the type of vinyl monomer used and the desired grafting rate, but it is usually 80°C or higher, preferably 100 to 120°C. Should. Further, the ratio of the ozonated block copolymer and vinyl monomer introduced into the polymerization reaction system may be selected as appropriate, but generally block copolymer/vinyl monomer = 2/1. ~1/3 (weight ratio). The grafting rate of the graft copolymer obtained here varies greatly depending on the reaction conditions, but is usually 45 to 95%.
Preferably it is 75-95%. In addition, various vinyl monomers used in this case include acrylic acid, acrylic ester, methacrylic acid, methacrylic ester, vinyl acetate, vinyl chloride, vinylidene chloride, acrylonitrile, styrene, acrylamide, and butadiene. be able to. According to the method of the present invention as described above, there is no reduction in molecular weight due to decomposition of the ethylene-propylene block copolymer during the ozone treatment step.
The resulting graft copolymer has high mechanical strength. Furthermore, since it is simultaneously treated with ozone, the grafting rate due to graft polymerization of the vinyl monomer is high, resulting in a graft copolymer with excellent adhesiveness and paintability. Therefore, the graft copolymer obtained by the method of the present invention can be effectively and widely used as a material for equipment such as household electrical appliances and automobile parts. Next, the present invention will be explained in more detail with reference to Examples. Example 1 (1) Ozonation of ethylene-propylene block copolymer As an ethylene-propylene block copolymer, the ethylene unit content was 7.0% by weight, the molecular weight of the ethylene block was 24000, and the molecular weight of the copolymer was
270,000 copolymer powder with an internal volume of 500
ml of ozone-containing gas with an ozone concentration of 30 mg/ml after adding 200 ml of water.
Ozonation was carried out by blowing into the reactor at a rate of 10/hr. Table 1 shows the rate of molecular weight reduction obtained by measuring the molecular weight every hour from the start of the reaction. (2) Grafting of styrene Ozonated ethylene obtained in (1) above
100 parts by weight of propylene block copolymer, 100 parts by weight of styrene, 1000 parts by weight of water and 0.5 parts by weight of polyvinyl alcohol were charged into a flask, and reacted at 100°C for 4 hours with stirring, resulting in a styrene unit content of 18% by weight. A graft copolymer was obtained. Table 2 shows the mechanical strength results of these graft copolymers. Further, Table 3 shows the results of the adhesive tape cross-cut peeling test for these graft copolymers and compositions prepared by mixing them with propylene homopolymer. Example 2 In Example 1 (2), the amount of styrene used was changed to 200
A graft copolymer having a styrene unit content of 45% by weight was obtained in the same manner as in Example 1(2) except that the reaction time was 6 hours. Table 2 shows the mechanical strength results, and Table 3 shows the results of the adhesion/burlap peel test. Example 3 In Example 1 (2), the amount of styrene used was reduced to 300
A graft copolymer having a styrene unit content of 63% by weight was obtained in the same manner as in Example 1(2) except that the reaction time was 8 hours. The mechanical strength results are shown in Table 2. Comparative Example 1 200 parts by weight of styrene, 1000 parts by weight of water, and 0.5 parts by weight of polyvinyl alcohol were charged into a flask with respect to 100 parts by weight of propylene homopolymer having a molecular weight of 155,000, and the mixture was reacted at 100°C for 3 hours with stirring until the styrene unit content was 18 parts by weight. % graft copolymer was obtained. The percentage of molecular weight reduction is shown in Table 1, and the mechanical strength results are shown in Table 2. Comparative Example 2 The styrene unit content was determined in the same manner as in Comparative Example 1, except that the amount of styrene used was 200 parts by weight and the reaction time was 5 hours.
A 45% by weight graft copolymer was obtained. The mechanical strength results are shown in Table 2. Comparative Example 3 The styrene unit content was determined in the same manner as in Comparative Example 1, except that the amount of styrene used was 300 parts by weight and the reaction time was 7 hours.
A 63% by weight graft copolymer was obtained. The mechanical strength results are shown in Table 2. Comparative Example 4 100 parts by weight of styrene for 100 parts by weight of ethylene-propylene random copolymer with a molecular weight of 155,000,
1000 parts by weight of water and 0.5 parts by weight of polyvinyl alcohol were placed in a flask and reacted at 100° C. with stirring for 4 hours to obtain a graft copolymer having a styrene unit content of 18% by weight. The percentage of molecular weight reduction is shown in Table 1, and the mechanical strength results are shown in Table 2. Comparative Example 5 The styrene unit content was determined in the same manner as in Comparative Example 4, except that the amount of styrene used was 200 parts by weight and the reaction time was 6 hours.
A 45% by weight graft copolymer was obtained. The mechanical strength results are shown in Table 2. Comparative Example 6 The styrene unit content was determined in the same manner as in Comparative Example 4, except that the amount of styrene used was 300 parts by weight and the reaction time was 8 hours.
A 63% by weight graft copolymer was obtained. The mechanical strength results are shown in Table 2.

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Claims (1)

[Claims] 1. In producing a graft copolymer by treating a propylene polymer with ozone and then grafting a vinyl monomer onto the obtained ozonated propylene polymer, as a propylene polymer, The ethylene unit content is 4-15% by weight, the molecular weight of the ethylene block is 20,000-45,000, and the overall molecular weight is
A method for producing a graft copolymer, characterized in that an ethylene-propylene block copolymer having a molecular weight of 250,000 to 350,000 is used. 2 The vinyl monomer is acrylic acid, acrylic ester, methacrylic acid, methacrylic ester,
2. The method according to claim 1, wherein vinyl acetate, vinyl chloride, vinylidene chloride, acrylonitrile, styrene, acrylamide or butadiene is used.