JPS5813645A - Resin composition containing organic peroxide in high concentration - Google Patents

Abstract

PURPOSE:To provide the titled composition capable of dispersing the organic peroxide homogeneously in a resin when charged together with resin pellets in an extruder, and stabilizing the rate of extrusion in extrusion molding of the resin, by adding an organic peroxide in high concentration to a resin containing specific amount of vinyl acetate. CONSTITUTION:100pts.wt. of a resin containing >=15wt% vinyl acetate (preferably an ethylene-vinyl acetate copolymer resin) is compounded with 10pts.wt. of an organic peroxide (preferably dicumyl peroxide). When the content of vinyl acetate in the above resin is less than 15wt%, the organic peroxide becomes liable to bleed to the surface of the pellets of the composition during the storage of the composition, and the homogeneous dispersion of the organic peroxide by the simultaneous charging to an extruder becomes difficult. An advantage of the process is elimination of the kneading process at a temperature above the melting point of resin pellet which is essential to the conventional method using a resin pellet and an organic peroxide.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a resin composition containing an organic peroxide in high conversion 11, which is used for manufacturing molded products such as pipes, sheets, containers, and covered electric wires.

Conventional molded products such as pipes, sheets, containers, etc. Most organic peroxide-containing resin compositions used in the production of electric wires contain 1 to 2 parts by weight of organic peroxide per 100 parts by weight of the resin.

A method for manufacturing molded element-covered wires such as pipes and sheets using such a resin composition is shown in FIG. 11 as a process diagram.

(1) Mix a predetermined amount of organic peroxide 2 with a certain amount of resin 1, and mix it into a panburi mixer, an open roll, or! The resin is kneaded at one or more points in a axial extruder at a temperature below the decomposition temperature of the organic peroxide to uniformly disperse the organic peroxide to obtain a granular molded product 4.

(2) In the next step i, the granular molded product 4 is fed to the extruder 6, and from the granular molded product 4, which is a crosslinkable resin composition, a pipe is formed.
Form into sheets, etc. Some i extrude this granular molded product onto a conductor to obtain a coating.

(3) A molded article such as a sheet or pipe made of the resin composition or a coated electric material is heated to a temperature at which the organic peroxide decomposes and then racked (116) to obtain a molded article 7.

However, when using such conventional organic peroxide-containing resin compositions, it is possible to obtain stable covered electric wires, but the manufacturing process always requires kneading and mixing of the resin and organic peroxide. This method has the disadvantage that equipment costs and processing costs are high because it requires a process of

As a method of omitting the kneading and mixing process of the resin and organic peroxide as described above, after weighing the resin pellets and the organic peroxide, both are fed into the extruder from the extruder hopper at the same time.
A possible method is to mix and extrude both in an extruder at the same time.

However, with this method, the organic peroxide is not uniformly dispersed during resin neutralization, and furthermore, the organic peroxide covers the resin pellet surface and acts like a lubricant, so the resin pellet does not lubricate and the extrusion rate is stable. However, this has also not been put to practical use.

As an alternative method, a method has been proposed in which a peroxide to be kneaded with the molten resin in the extruder is placed in several places in the extruder cylinder and then press-fitted from the round cylinder inlet. (% Kaisho 5
(No. 3-75487, No. 58-115079) According to this method, the dispersion and extrusion amount of the organic peroxide are relatively stable, but 1. There are disadvantages in that the extruder cylinder requires several injection ports and the rounding equipment is expensive, and furthermore, it is difficult to maintain a constant supply ratio of organic peroxide to resin.

This invention was made as a result of intensive studies in order to improve the various drawbacks during molding, such as crosstalk between resin and organic peroxide, in the conventional methods described above.

That is, in this invention, the organic peroxide to be charged together with the extruder K11 fat pellets is a resin composition containing a high organic peroxide content as described below.
It was discovered that the oxide is uniformly dispersed in the resin and that the extrusion rate is also stable.

The following explanation will be based on a resin composition containing a high degree of organic peroxide (hereinafter simply referred to as a resin composition), which is the ζO invention. It is obtained by adding 10 parts by weight or more of an organic peroxide to each part and kneading and mixing with an open roll or the like. The reason why the content of vinyl acetate in the resin used here is defined as 15 weight or more is that if the content is 15 weight or less, organic peroxide may be dissolved in the composition particles during storage of the resulting resin composition. This is because organic peroxides tend to bleed easily, and as a result, it is difficult for the organic peroxide to be uniformly dispersed in the resin pellets during extrusion when they are added together with the resin pellets, and the amount of extrusion varies, making it impractical.

Furthermore, the reason why the amount of organic peroxide to be added to the resin is 10 parts by weight or more is that if it is less than 10 parts by weight, a certain amount of organic peroxide will be added to the composition (for example, a cable coating composition) that does not contain organic peroxide. This is because when adding the oxide, a large amount of the organic peroxide-containing resin composition must be added to the resin pellet, which increases the material cost. □ However, the process of forming pipes, sheets, etc. and manufacturing covered wires when using the resin composition containing a high concentration of organic peroxide of the present invention is explained with reference to Fig. 2.Resin pellets) 1
1 and the required amount of organic peroxide high chain degree-containing resin composition 1 tvt were simultaneously charged into the extruder 18, both were uniformly dispersed and extruded into a KPk tatami shape, and then heated on a heating rack*141° A molded article 15 is obtained.

As described above, by using an organic peroxide as the organic persulfide-rich am-containing resin composition of the present invention, the organic peroxide is uniformly dispersed in the resin pellets in the extruder. In the case of using conventional resin pellets and organic peroxide, it is possible to completely omit the step of kneading at a temperature higher than the melting point of the resin pellets, which has the effect of shortening the process and reducing costs accordingly. It's nine.

Examples of molded products made from such a resin composition containing a high organic peroxide chain degree and resin pellets include molded products such as coated electrical conductors, pipes, sheets, tapes, and containers.

The resin containing 15 weight or more of vinyl acetate used in this invention includes copolymers of vinyl acetate such as ethylene-vinyl acetate copolymer, and polyvinyl acetate in plastics containing 15 weight or more of vinyl acetate. Among them, ethylene-vinyl acetate copolymer is most preferred.

In addition, examples of organic peroxides include dicumyl peroxide,
Ditertiary-butyl peroxide, 2,5-dimethyl 2,5-di(tertiarybutylperoxide)hexant, l,8-bis(tertiarybutylperoxide, I&,<-
Oxyquiisopropyl)benzene, 2,5-dimethyl2.
Examples include 5-di(hydroperoquine)hexane, but dicumyl peroxide has a decomposition half-life of 10 hours (116°C).
Since polyethylene is molded at a temperature of about 1,200°C, so-called burning due to the decomposition of dicumyl peroxide (DCP) is less likely to occur, and when crosslinking, for example, with steam crosslinking, it is crosslinked at a temperature of about 200°C, which is sufficient. Can be crosslinked in series.

It is most preferable because of the following points.

This is true for DCP as well, when the temperature is high (half-life: 10 hrs).
) Burning is likely to occur during crosslinking, and if the temperature is lower than that of reverse KDCP, the crosslinking time will be long () and the production rate will be slow.

This invention will be explained in detail by way of examples.

Example Dicumyl peroxide (DCP) as an organic sensitizer
Using @1ilK as shown in Table 1, each was kneaded and mixed using an open roll to form pellets. Next, these were left at room temperature for one week, and the amount of dicumyl peroxinide oozed out on the surface of the resin pellet was determined.9. The results are shown in Table 1.

As a comparative example, a resin with a vinyl acetate content of 16% or less and a low-density polyethylene KDCP were blended and the circle was OK.
Bleed amount O was determined in the same manner.

Note: *1 The amount of bleed is determined by washing the surface of the AM set zoo bed with the formulation shown in the table above with methanol.

After cleaning, the pellet was subjected to Soxhlet extraction with methanol, and the extract was analyzed with a liquid chromagraph to determine the amount of DCP remaining in the pellet and calculate the amount of bleed. In addition, the bleeding amount wt9G is the ratio of DCP to the blended iLK.

Hata 20: DCP bleeding amount of 10% or less was considered good.

×・・・DCP bleed amount 10% or more □
was considered defective.

Next, as shown in Table 2, for 100 parts of low density polyethylene! After mixing the single bond organic peroxide-containing am composition so that the amount of organic peroxide was ~2 parts by weight, it was poured into a 50 cm extrusion root hopper to observe the change in extrusion amount over time. The results were as shown in Table 2.

After 2 hours of extrusion molding the extruded resin rod
After heating and crosslinking in high pressure steam for 80 minutes, this crosslinked extrusion & H1m rod 16 was subjected to iT as shown in Figure 8.
Table 2 also shows the measurement results of the gel fraction (xylene insoluble content at 120°C) at four points: himA, B, C, and the center.

From the above Tables 1 and 2, it can be seen that in the implementation of the present invention, DCP bleed is small and the extrusion amount fluctuates less, whereas in the comparative examples, DCP bleed is large and the extrusion amount is small. It has been proven that this method is impractical due to its large size and large fluctuations.

In addition, an attempt was made to directly feed low-density polyethylene and DCP from the extruder hopper, but the materials slipped in the extruder and could not be extruded after 5 minutes.

Furthermore, we tried mixing 100 parts by weight of DCP with 100 parts by weight of low-density polyethylene using an open roll at a temperature above the melting point of polyethylene, pelletizing it, and feeding it to the extruder, but the extrusion amount was immediately after extrusion: 161F, 10 minutes later. :
1621F, 80 minutes later: 1482° 1 hour i: 16
0f, 2 hours later: 151F, average = 160.8f, and the difference between the maximum and minimum extrusion amount was 6t, indicating that the above embodiment of the present invention had workability equivalent to the conventional one. .

[Brief explanation of the drawing]

Fig. 1 is a process diagram of extrusion molding using conventional resin pellets and organic peroxide, and Fig. 2 is a process diagram of extrusion molding using a resin composition containing a high concentration of organic peroxide and resin pellets of the present invention. FIG. 3 is a diagonal RE of #resin rod showing the gel fraction measurement points in the crosslinked extrusion molded resin rod. Patent applicant: Sumitomo Electric Industries, Ltd. Agent: Patent Attorney Kazu1) Figure 1, Figure 2, Figure 3, Procedural amendments stamped) April 13, 1980 Commissioner of the Japan Patent Office Haruki Shimada, 1, Indication of the case 1981 Patent Application No. 111917 2, Title of invention: Resin composition containing high concentration of organic peroxide 3, Relationship to the case of the person making the amendment Patent applicant address: 15-15 Kitahama 5-chome, Higashi-ku, Osaka ,
□) (213) Sumitomo Electric Industries, Ltd. 4, Agent 6, Number of 庭-s increased by amendment 7, Contents of amendment subject to amendment 1, Page 8 of the specification, lines 4-7, “This... This is because if an organic peroxide with a low temperature at a decomposition half-life of 10 hours (half-life of 10 hrs) is used for DCP, burns are likely to occur during crosslinking; Degradation half-life of DCP 10
This is because if an organic peroxide is used at a temperature higher than that for the time, the crosslinking time becomes longer and the production rate becomes slower. ” I am corrected.

Claims (3)

[Claims] (1) Resin 100 containing 15 weight or more of #identical vinyl
A resin composition containing a high chain degree of organic peroxide, which contains 10 parts by weight or more of an organic peroxide. (2) The organic peroxide high chain degree-containing resin composition according to claim 1, wherein an ethylene-vinyl acetate copolymer resin is used as the resin containing 16 weight or more of vinyl acetate. (3) A resin product containing an organic peroxide with a high 111ffi content as set forth in claim 1, wherein dicumyl peroxide is used as the organic peroxide.