JP3342896B2 - Method for bonding ethylene-propylene-diene rubber composite - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for bonding a vulcanized rubber composite comprising an ethylene-propylene-diene rubber.

[0002]

2. Description of the Related Art Ethylene-propylene-diene rubber (hereinafter abbreviated as EPDM) is an ozone-resistant, aging-resistant,
It has many excellent properties such as heat resistance and low temperature properties, and if these properties are utilized, it can be used for outdoor rubber products in many applications. However, EPDM after vulcanization has extremely low adhesiveness and is extremely difficult to adhere to the same or other types of rubber materials, so that it is hardly applicable to many applications. It has been reported that the use of ultrahigh molecular weight polyethylene enables adhesion, but it is often difficult to make ultrahigh molecular weight polyethylene into a sheet or film.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide an EP
It is an object of the present invention to provide a bonding method which makes it possible to easily and firmly bond a vulcanized rubber made of DM with a rubber of the same type or another type.

[0004]

In order to achieve the above object, the present invention provides a vulcanized EPDM rubber and a critical surface tension γc.
(Hereinafter abbreviated as γc) 25 to 29 millinewton / meter (hereinafter abbreviated as mN / m) and an unvulcanized rubber made of a raw rubber with a high-density polyethylene in a molten state interposed therebetween. It is characterized by a bonding method or a bonding method in which a high-density polyethylene in a molten state is interposed between vulcanized rubbers made of EPDM.

[0005] As described above, by interposing a high-density polyethylene in a molten state between EPDM vulcanized rubber and the same or another rubber which has been conventionally difficult to adhere, both rubbers can be easily and firmly bonded. Can be glued. In the present invention, the critical surface tension γc, using a raw rubber cut flat with a sharp razor with water,
When measuring the contact angle θ of liquids in a homologous series of liquid hydrocarbons and other organic liquid compounds on the surface of the rubber sample and plotting cos θ and γ with γ as the surface tension of those liquids, A substantially straight line irrespective of the type of liquid in the row can be obtained.
0, that is, γc corresponding to cos θ = 1 (Showa
August 20, 1953, Maruzen Co., Ltd. “Chemical Handbook” Basic Edition II
(3rd print), page 618).

[0006] The vulcanized rubber comprising EPDM used in the present invention is not particularly limited, and a vulcanized rubber composition containing a commercially available EPDM as a raw rubber is molded into an arbitrary shape and vulcanized. Is done. In the present invention, EP
As unvulcanized rubber to be adhered to DM vulcanized rubber,
An unvulcanized rubber made of a rubber composition containing a raw rubber having a γc of 25 to 29 mN / m is used. If a raw rubber having γc outside the above range is used, even if high-density polyethylene in a molten state is interposed, it cannot be firmly bonded to the EPDM vulcanized rubber. As the raw rubber having γc in the above range, ethylene-propylene-diene rubber (EP
DM, γc = 28 mN / m) and isobutylene-isoprene copolymer rubber (IIR, γc = 27 mN / m).

The raw rubber EPDM used in the present invention and the raw rubber of γc include carbon black, zinc oxide,
It can be used as a rubber composition containing a predetermined amount of stearic acid, process oil, antioxidant, sulfur, vulcanization accelerator, and other various rubber chemicals. In this case, it is desirable that raw rubber such as EPDM occupies at least 50% by weight of the rubber composition as a matrix. In addition, these rubber compositions are plate-shaped according to each application,
It is used by being preformed into an arbitrary stackable shape such as a sheet, a rod, and a tube.

In the present invention, the high-density polyethylene used for bonding is not particularly limited, and a commercially available product can be used. Preferably the density is 0.93
It is preferable to use polyethylene having a melt viscosity index (melt flow rate MFR) of 7.0 or more and a molecular weight-related melt viscosity index of 7.0 or less. Desirably, polyethylene having a density of 0.935 to 0.960 is used.

The above density and MFR are both JIS K-
It is a value measured according to the test method according to 6760. In the present invention, when high-density polyethylene is used as an adhesive medium, it must be in a molten state during the adhesive treatment. This molten state may be made into a sheet-like or powder-like solid state in advance, interposed between rubber materials to be bonded, and then heated to a melting point of polyethylene (135 ° C.) or more to be melted. Alternatively, the material may be directly melt-extruded into a plate shape or a film shape from a melt extruder or the like. When a plate or powdered high-density polyethylene is subjected to bonding while being heated and melted to a temperature higher than its melting point, it is preferable to apply a slight pressure, and to perform pressure bonding. When one of the rubber materials is an unvulcanized rubber, the time for the pressure bonding is desirably a time sufficient to complete the vulcanization.

When a high-density polyethylene sheet is used as a sheet as described above, the thickness of the sheet is not particularly limited. However, if the thickness is more than 0.5 mm and is too thick, the adhesive strength is large but the adhesive layer impairs flexibility. Further, when high-density polyethylene is subjected to bonding while being melt-extruded, good bonding is obtained by pressing at the time of bonding, and 220 ° C.
As long as it is used in the following, the adhesive strength can be enhanced to the cohesive failure state of the vulcanized rubber.

[0011]

EXPERIMENTAL EXAMPLE 1 Four types of rubber compositions having the composition shown in Table 1 (raw rubber EPDM, γc = 28 mN / m), a (raw rubber IIR, γc = 27 mN / m), c (raw material) Rubber NR, γ
c = 31 mN / m) and d (raw rubber SBR, γc = 3)
3 mN / m). From these rubber compositions A to D, sheet-like unvulcanized rubber materials A, B, C and D of 150 mm × 50 mm × 2.5 mm were formed, respectively. here,
EPT3045 (Mitsui Chemicals) as raw rubber EPDM
As raw rubber IIR as Butyl 268 (Exxonized
), RSS # 1 as raw rubber NR, raw rubber NR
Nipol 1702 (Nihon Zeon) for SBR
Was .

The unvulcanized rubber material A was vulcanized to prepare a vulcanized rubber material A '. Furthermore, the density = 0.946,
Thickness 2 made of high-density polyethylene with MFR = 0.04
A 00 μm sheet was prepared. High-density polyethylene
S6008G (Japanese polyolefin) was used .
The high-density polyethylene sheets are individually sandwiched between the EPDM vulcanized rubber material A 'and the unvulcanized rubber materials A, B, C, and D, respectively, heated at 160 ° C. to melt the same, and By pressing at a pressure of / cm ² for 20 minutes, the unvulcanized rubber materials A, B, C, and D were simultaneously vulcanized and bonded to the vulcanized rubber material A ′.

[0013] All numerical values in Table 1 are parts by weight.

* 1 is N-phenyl-N'-isopropyl-p-phenylenediamine * 2 is Nt-butyl-2-benzothiazolesulfenamide * 3 is tetramethylthiuram disulfide * 4 is 2-mercapto Benzothiazole * 5 is tetramethylthiuram monosulfide * 6 is benzothiazyl disulfide.

The resulting four types of rubber-rubber composite A'-
The adhesiveness of A (Example 1), A'-B (Example 2), A'-C (Comparative Example 1), and A'-D (Comparative Example 2) was evaluated by the following methods. Evaluation method of adhesiveness : It is not accurate to evaluate the adhesiveness of the rubber-rubber composite by the magnitude of the adhesive force. So, width 2
A sample of 0 mm was prepared and subjected to a peeling test. When interfacial peeling occurred, it was evaluated as poor (x) even if the adhesive strength was high. On the other hand, when no interfacial peeling occurred, about 0.5% centered on the adhesive interface of the rubber / rubber composite.
A sheet with a thickness of mm was cut out with a razor, and a razor was used to cut the area near the interface, and the peeling test was repeated five times. If one of the sheets adhered strongly enough to cause cohesive failure inside, it was bonded. It was evaluated as good (良好).

As a result, the adhesiveness of the composites of Examples 1 and 2 was all ○. On the other hand, the adhesiveness of the composites of Comparative Examples 1 and 2 was poor, and the adhesiveness between the high-density polyethylene and the rubber materials C and D was poor, respectively. Experimental Example 2 Two vulcanized rubber materials A ′ produced in the same manner as in Experimental Example 1.
The high-density polyethylene sheets are interposed between each other and between the vulcanized rubber material A ′ and the vulcanized rubber material C ′ obtained from the unvulcanized rubber material C, respectively, and are pressed under a pressure of 20 kg / cm ² under a pressure of 160 kg. By heating at 20 ° C for 20 minutes.
Rubber composites A′-A ′ (Example 3) and A′-C ′ (Comparative Example 3) were obtained.

The adhesiveness of each of the composites of Example 3 and Comparative Example 3 was evaluated by the above-described measurement methods. as a result,
The adhesiveness of the composite of Example 3 was ○, but the adhesiveness of the composite of Comparative Example 3 was ×. Experimental Example 3 As in Experimental Example 1, two ends of the vulcanized rubber material A 'were overlapped with both ends shifted, and a high-density polyethylene was melt-extruded at 200 ° C. using a manual extruder at the overlapped portion. While applying. After sufficient cooling, a rubber-rubber composite A′-A ′ (Example 4) was obtained. The adhesiveness of the composite of Example 4 was evaluated by the method described above. As a result, the adhesiveness was good (○).

EXPERIMENTAL EXAMPLE 4 Between the two vulcanized rubber materials A 'of experimental example 1 (thickness 2 mm), two types of thicknesses 0.2 mm each having a density and a melt flow rate (MFR) shown in Table 2. Polyethylene film (a) and (b), respectively;
Minutes, heat and pressure to adhere, rubber-rubber composite A'-
A ′ (Examples 5 and 6) was obtained. The adhesiveness of the composites of Examples 5 and 6 was evaluated by the above measurement method. As a result, the adhesiveness was ○ in all cases.

[0019] Experimental Example 5 A low density (0.922) and a high MFR (1) shown in Table 3 were placed between the two vulcanized rubber materials A '(2 mm thick) of Experimental Example 1.
7) Two types of 0.2 mm thick polyethylene films (c) and (d) are interposed, respectively,
, Rubber-rubber composite A'-
A ′ (Comparative Examples 4 and 5) was obtained.

The adhesiveness of the composites of Comparative Examples 4 and 5 was evaluated by the above-described measurement methods. As a result, the adhesiveness was X in all cases. This is because the composite of Comparative Example 4 had a low density of the polyethylene film (c), and the composite of Comparative Example 5 had too high a MFR of the polyethylene film (d), so that the flowability of the melted polyethylene was low. It is considered that it is low.

[0021]

[0022]

According to the present invention, between an EPDM vulcanized rubber and an unvulcanized rubber containing a rubber having a specific γc,
By adhering the high-density polyethylene in the molten state between the DM vulcanized rubbers, the two rubbers can be firmly adhered. For this reason, E which has excellent performance
The use of PDM vulcanized rubber can be expanded and utilized effectively.

Claims (2)

(57) [Claims] 1. A high-density polyethylene in a molten state between a vulcanized rubber composed of an ethylene-propylene-diene rubber and an unvulcanized rubber composed of a raw rubber having a critical surface tension γc of 25 to 29 millinewton / meter. A method for bonding an ethylene-propylene-diene-based rubber composite, characterized in that the bonding is carried out by interposing a rubber. 2. A high-density polyethylene in a molten state is interposed and bonded between vulcanized rubbers composed of an ethylene-propylene-diene rubber.
A method for bonding a propylene-diene rubber composite.