Patent Application
20080071029
The components in the amounts (parts by weight) as shown in Table 1 were melt kneaded with a twin-screw kneader of L/D=30 at the lowest possible production temperature shown in Table 1 to obtain a resin composition, followed by pelletization. The pellets obtained were compression molded into test specimens, which were then subjected to the aforesaid tests (1) to (7). In place of the resin composition, use was made of a phenolic resin consisting solely of Component (a) of the present invention (trade name: Tackirol 201) in Comparative Example 7, and a masterbatch comprising a phenolic resin and butyl rubber (trade name: Tackrol 201 MB35; consisting of 35% by weight of butyl rubber, 30% by weight of non-brominated phenolic resin and 35% by weight of clay) in Comparative Example 8. The results are as shown in Table 1.
Using the resin compositions obtained in Examples 1 to 3 and Comparative Examples 1 to 10, the thermoplastic elastomer compositions were produced in Examples 4 to 9 and Comparative Examples 11 to 20. The formulations of the thermoplastic elastomer compositions are as shown in Table 2. In place of the resin composition, use was made of a phenolic resin consisting solely of Component (a) of the present invention (trade name: Tackirol 201) in Comparative Example 17, and a masterbatch comprising a phenolic resin and butyl rubber (trade name: Tackirol 201 MB35; comprising 35% by weight of butyl rubber, 30% by weight of non-brominated phenolic resin and 35% by weight of clay) in Comparative Example 18. The production was carried out by charging the components of the amounts (parts by weight) shown in Table 2 into a press kneader type mixer of a capacity of 3 L and melt kneading them at a temperature set at 180° C. for 10 minutes. The thermoplastic elastomer compositions obtained were subjected to the aforesaid tests (8) to (10). The results are as shown in Table 2.
As seen from Table 1, the resin compositions of Examples 1 to 3 according to the present invention could be easily kneaded in a twin-screw kneader at a lower kneading temperature and could be pelletized. The pellets obtained showed no blocking and caused no dust in handling. As seen from Table 2, the resin compositions according to the present invention could yield more uniform cross-linking and, at the same time, could improve compression set of the thermoplastic elastomer compositions obtained and emitted less toxic gases during the production of the thermoplastic elastomer compositions, so that the resin compositions are useful as a masterbatch of a cross-linking agent.
On the other hand, the amount of Component (b), (c) or (d) in the formulations is outside the ranges of the present invention in the resin compositions of Comparative Examples 1 to 6. As seen from Table 1, the resin composition of Comparative Example 1 where the amount of Component (b) is below the range of the present invention and the resin composition of Comparative Example 4 where the amount of Component (c) exceeds the range of the present invention were both able to be produced and pelletized, but caused blocking of pellets, leading to a trouble in handling such that the blocked pellets had to be broken up to be used as a masterbatch of a cross-linking agent. The resin composition of Comparative Example 2 where the amount of Component (b) exceeds the range of the present invention results, as seen from Table 2, in the inferior compression set of the thermoplastic elastomer composition obtained from it (see Comparative Example 12). Both in the resin composition of Comparative Example 3 where the amount of Component (c) is below the range of the present invention and the resin composition of Comparative Example 6 where the amount of Component (d) exceeds the range of the present invention, the load during the production of the resin composition tended to exceed the upper limit of load of the kneader, which made stable production difficult to attain. The resin composition of Comparative Example 5 where the amount of Component (d) is below the range of the present invention has the lowest possible production temperature of 260° C. and, as a result, the thermoplastic elastomer composition obtained from it is inferior in compression set as seen from Table 2, Comparative Example 15. This indicates that because the resin composition of Comparative Example 5 was produced at a higher temperature, the phenolic resin deteriorated and, as a consequence, the cross-linking ability of the resin composition became worse.
In Comparative Examples 7 and 17, the phenolic resin alone was used in place of the resin composition of the present invention. The phenolic resin was of hard and brittle masses, whose shape was irregular, accompanied with a large amount of crumbled powder. Therefore, non-uniformity in composition tended to occur in the blending of the components of the thermoplastic elastomer composition. In addition, because the phenolic resin was hard and brittle, dust occurred in the handling. Further, as seen in Table 2, uniform cross-linking was not attained in the obtained thermoplastic elastomer compositions and the toxic gases occurred during the production of the thermoplastic elastomer composition.
In Comparative Examples 8 and 18, the phenolic resin masterbatch comprising butyl rubber was used in place of the resin composition of the present invention. The masterbatch comprising butyl rubber was of a tile form and can not be palletized. It had to be cut in pieces with a guillotine cutter before used, which took much time and works. In addition, as seen in Table 2, uniform cross-linking was not obtained with the masterbatch comprising butyl rubber.
In Comparative Examples 9 and 10, comparative Components (b), i.e., ethylene-vinyl acetate copolymer and ethylene-methylmethacrylate copolymer were used, respectively. As seen from Table 1, the anti-blocking property was poorer. The thermoplastic elastomer compositions obtained from the resin compositions of Comparative Examples 9 and 10 were, as seen from Table 2, inferior in compression set and the shaped articles therefrom had many hard spots (see Comparative Examples 19 and 20).
