JPS6047285B2 - Production method of acrylonitrile polymer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a gas-impermeable acrylonitrile polymer having excellent alcohol resistance and transparency.

In recent years, molding acrylonitrile resins with high acrylonitrile content have been used for food packaging films, carbonated beverages, liquid foods, cosmetic containers, etc. due to their gas impermeability, water vapor impermeability, and transparency. It is becoming widely used.

Such acrylonitrile resins include copolymers of acrylonitrile and acrylic acid alkyl esters or methacrylic acid alkyl esters having an alkyl group with a small number of carbon atoms, or the presence of a rubber-like polymer for the purpose of improving impact resistance. Copolymers prepared by copolymerizing the monomer mixtures described below are known. However, molded products made from these acrylonitrile-based polymers and polymers have the disadvantage of becoming cloudy and reducing transparency when they come into contact with moisture.

This drawback detracts from its value as a packaging material.
As a method to improve this drawback, one or two types of acrylonitrile and aphacrylic acid alkyl esters having an alkyl group with a small number of carbon atoms, such as methyl acrylate, ethyl acrylate, and methacrylic acid alkyl esters, such as methyl methacrylate and ethyl methacrylate, are used. In addition to the above, octyl acrylate can be added and copolymerized to improve impact resistance, by copolymerizing in the presence of a rubber polymer, and by contact with moisture. A method for obtaining an acrylonitrile polymer with excellent water resistance without clouding has been proposed (Japanese Patent Publication No. 49-21
(See Publication No. 105). However, although the acrylonitrile polymer obtained by this method has improved water resistance, it is used for containers for beer, sake, whiskey, ajirin, etc. containing ethyl alcohol, cosmetic containers, and food products containing ethyl alcohol. When used in packaging films, etc.
Similarly to the case of using an acrylonitrile-based polymer obtained by copolymerizing acrylonitrile with an acrylic acid alkyl ester or a methacrylic acid alkyl ester having a small number of carbon atoms or a mixture of these monomers in the presence of a comb-like polymer. This phenomenon is particularly unsatisfactory in that it becomes cloudy, and this phenomenon is accelerated by an increase in temperature, impairing the originally transparent property and lowering the commercial value. The prevention of cloudiness caused by bringing an acrylonitrile polymer into contact with an ethyl alcohol-containing substance can be achieved by simply imparting water resistance to the acrylonitrile polymer, that is, preventing cloudiness caused by water. However, it is necessary to provide alcohol resistance in addition to water resistance. As a result of extensive research aimed at improving the drawback of acrylonitrile-based polymers causing cloudiness when they come into contact with ethyl alcohol-containing substances as described above, the inventors have found that they have been found to be transparent and alcoholic. We have discovered a method for producing a gas-impermeable acrylonitrile polymer with excellent clarity.

That is, the method for producing a gas-impermeable acrylonitrile polymer having excellent alcohol resistance and transparency according to the present invention comprises 50 to 90% by weight of acrylonitrile, an acrylic acid alkyl ester having an alkyl group having 13 to 6 carbon atoms, and One or more types selected from methacrylic acid alkyl esters 1 to 4% by weight and one or more types selected from methacrylic acid alkyl esters having an alkyl group having 12 to 18 carbon atoms 41 to 15% by weight % preferably 1-10% by weight
It is characterized in that it is copolymerized with.

Furthermore, in the present invention, when copolymerizing such a monomer mixture, 10 parts by volume of the monomer mixture are added to 5 to 5 parts of the rubbery polymer (
By copolymerizing in the presence of the following parts by weight, it is possible to obtain an acrylonitrile polymer having improved impact resistance in addition to the above-mentioned properties. In the present invention, a methacrylic acid alkyl ester having an alkyl group having 12 to 18 carbon atoms as a copolymerization component is an essential component for obtaining an acrylonitrile polymer with excellent alcohol resistance and transparency. It is also an important component because it has been observed that the resulting polymer has improved fluidity in rivers during processing, compared to the case of using conventional lower alkyl methacrylates.

According to a light transmittance test, the effect of these methacrylic acid alkyl esters having an alkyl group of 12 to 18 carbon atoms on alcohol resistance is as follows. Although it improves as the number of prime numbers increases, the difference due to the light transmittance is almost invisible when observed with the naked eye.

The methacrylic acid alkyl ester having an alkyl group having 12 to 18 carbon atoms used in the present invention has 12 to 18 carbon atoms.
In the case of an acrylonitrile polymer substituted with an acrylic acid alkyl ester having 2 alkyl groups, no improvement in alcohol resistance is observed, and the transparency of the molded product decreases. Regarding the amount of the methacrylic acid alkyl ester having an alkyl group having 12 to 18 carbon atoms used in the present invention, the effect is recognized at 1% by weight or more based on the total monomer, and as the amount increases, the alcohol resistance increases. However, if it is used in an amount exceeding 15% by weight, the degree of improvement reaches saturation, and peeling phenomena may occur in the melt-molded product, so it is preferable to use 15% by weight or less.

Examples of the methacrylic acid alkyl ester having an alkyl group having 12 to 18 carbon atoms include lauryl methacrylate, tridecyl methacrylate, myristyl methacrylate, cetyl methacrylate, and stearyl methacrylate. The amount of acrylonitrile used in the production of the acrylonitrile-based polymer in the present invention is required to be 5% or more in order to provide gas impermeability, but even if it exceeds 9%, melt molding processability remains. The amount is 50 to 90% by weight because it lowers the amount of carbon and is impractical. The alkyl esters and alkyl methacrylates having an alkyl group having 1 to 6 carbon atoms used to produce the acrylonitrile polymer with excellent alcohol resistance and transparency of the present invention include methyl acrylate, Examples include ethyl acrylate, propyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, etc. If the amount of these used is small, the moldability of the polymer will deteriorate; Since this results in poor gas impermeability, the preferred amount of these used is 1 to 1% by weight.

Examples of the rubbery polymer include diene homo rubbery polymers such as polybutadiene and polyisoprene, or diene rubbery copolymers preferably containing diene in an amount of (a) % or more by weight, such as acrylonitrile-butadiene rubbery copolymers;
Examples include rubbery copolymers of acrylonitrile-butadiene-isoprene, and rubbery copolymers of conjugated dienes and alkyl acrylates and alkyl methacrylates such as methyl acrylate or ethyl acrylate.

Even when a rubbery polymer is used, in order to achieve the transparency of the acrylonitrile polymer, which is the gist of the present invention, the type and composition of the rubbery polymer can be adjusted according to conventionally known methods. It is preferable to select it appropriately depending on the composition of the monomer mixture. For the production of the acrylonitrile polymer in the present invention, known methods such as bulk polymerization, solution polymerization, suspension polymerization, and emulsion polymerization can be used, but emulsion polymerization is preferred. Further, when copolymerizing in the presence of a rubbery polymer, it is preferable to use an emulsified latex-like rubbery polymer. In addition, when producing the acrylonitrile polymer of the present invention, it is preferable that the methacrylic acid alkyl ester having an alkyl group having 12 to 18 carbon atoms be mixed before the start of copolymerization, and the monomers involved in copolymerization The copolymer can also be obtained by a batch method in which polymers and other components are added continuously or intermittently. The present invention will be explained below by way of examples.

All parts and percentages in the examples are based on weight unless otherwise specified. 88 Example 1 Monomer mixture shown in Table 1 10-, n-dodecyl mercaptan 1.5 parts, sodium lauryl sulfate 0.8 parts, anhydrous sodium pyrophosphate 01 parts, potassium persulfate 0.08 parts and water 200 parts A portion of the mixture was placed in an autoclave, and polymerization was carried out at 55° C. for 2 hours while stirring under a nitrogen atmosphere.

The conversion rate of the monomer mixture is the NO. of the present invention. l, 2, 3 and 4 are 96%, 95%, 95% and 95%, respectively;
Also, comparative example NO. l, 2, 3, 4 and 5 are each 97%,
The results were 96%, 95%, 94%, and 94%, and good latex was obtained in all cases. Next, each latex was salted out with a 0.4% aluminum sulfate aqueous solution, and
After washing with water, a white powdery polymer was obtained by drying at 60'C for an hour.

The thus obtained white powdery polymer was melt-kneaded for 3 minutes with a heating roll at 160'C to make a roll sheet, and this roll sheet was preheated with a 1700C heating press for 5 minutes.
After applying pressure for 5 minutes, it was cooled to produce a sheet with a glossy surface.

Next, the alcohol resistance of each sheet was tested using the following method.

Chemical resistance test Based on ASTM D543-67, the sheet was immersed in a 50% ethyl alcohol aqueous solution set at 50°C for 3 hours, and the sheet before and after immersion was rated JISK67l4.
Parallel light transmittance was measured based on the test method. In order to see the rate of decrease in parallel light transmittance before and after dipping, the ratio of parallel light transmittance before and after dipping was expressed as a percentage. These results are summarized in Table 1. Although there are slight differences between the samples in the light transmittance of the sheets of the present invention after immersion, the differences cannot be determined with the naked eye since all the sheets are transparent.

However, in Comparative Examples 4 and 5, the sheets before immersion were also slightly cloudy, and in Comparative Examples 1, 2, 3, 4, and 5, the sheets after immersion were obviously cloudy, and the transparency before and after immersion was significantly reduced. . Example 2 Polymerization recipe of rubbery polymer (Part) Acrylonitrile 301.3-Butadiene 70T-dodecylmercaptan 0.4 Sodium lauryl sulfate
1.5Na2c030.2Kyumene hydroperoxide (CHP) 0.08
Ferrous sulfate heptahydrate 0.01 Dextrose 0.5 EDTA-Disodium monohydride
0.02 water
200 Of the above polymerization recipe, everything except CHP was charged into an autoclave and the temperature of the reaction system was adjusted to 5°C under a nitrogen atmosphere, and then CHP was added to the system to give -15
The reaction was completed while stirring.

The conversion rate of the monomer mixture was 97%, and a good acrylonitrile-butadiene copolymer (NBR) latex was obtained. 15 parts of this NBR latex (as solid content),
1 (1) part of the monomer mixture shown in Table 2, 1.5 parts of n-dodecyl mercaptan, 0.8 parts of sodium lauryl sulfate, 0.0 parts of anhydrous sodium pyrophosphate. ? , 0.08 parts of potassium persulfate, and 2 (1) parts of water were placed in an autoclave, and polymerization was carried out at 55° C. for a period of time with stirring under a nitrogen atmosphere to complete the reaction.

The conversion rate of the monomer mixture is as per Invention Example No. 5, 6 and 7, respectively, are 95%, 96% and 95%, and Comparative Example N
O. 6, 7, and 8 were 95%, 95%, and 94%, respectively, and good latexes were obtained in all cases. Further, each latex was salted out with a 0.4% aluminum sulfate aqueous solution, washed with water, and dried at 60° C. for a period of time to obtain a white powdery polymer.

The white powdery polymer thus obtained was melt-kneaded for 3 minutes with a heated roll at 160°C to make a rolled sheet, and this rolled sheet was further preheated with a 1700°C heating press for 5 minutes.
17077 with a glossy surface after cooling for 5 minutes under pressure!
A sheet was made and an alcohol resistance test was conducted using the method described in Example 1.

In addition, in order to check gas impermeability, we used a heated breather to
．． 1rf0n film was created and ASTM D-143
The oxygen permeability was measured based on the test method No. 4-63. Furthermore, the impact strength of the sheet was measured based on the test method of JISK-6871. These measurement results are summarized in Table 3. As shown in Table 3, each sample of the present invention had good initial transparency and also excellent transparency after immersion in alcohol.

Claims (1)

[Claims] 1 50-90% by weight of acrylonitrile and 1-6 carbon atoms
1 to 40% by weight of one or more selected from acrylic acid alkyl esters and methacrylic acid alkyl esters having alkyl groups of A method for producing an acrylonitrile polymer having excellent alcohol resistance and transparency, which comprises copolymerizing 1 to 15% by weight of one or more types. 2 Acrylonitrile 50-90% by weight and carbon number 1-6
1 to 40% by weight of one or more selected from acrylic acid alkyl esters and methacrylic acid alkyl esters having alkyl groups of Acrylonitrile system with excellent alcohol resistance and transparency, made by copolymerizing 100 parts by weight of a monomer mixture consisting of 1 to 15% by weight of one or more types in the presence of 5 to 30 parts by weight of a rubbery polymer. Polymer manufacturing method.