JPS63256680A - Sealant rubber composition - Google Patents

Abstract

PURPOSE:To obtain the title composition which has excellent yield resistance and sealing properties, and an excellent sound insulating effect, and is suitable for insertion between a vehicle tank and a body panel, by incorporating ZnO and/or PbO and a plasticizer into a polymer blend of a butadiene/acrylonitrile copolymer and PVC. CONSTITUTION:100pts.wt. polymer blend consisting of 60-80wt.% butadiene/ acrylonitrile copolymer and 20-40wt.% PVC is mixed with 150-400pts.wt. ZnO and/or PbO; 5-30pts.wt. plasticizer such as dibutyl adipate; and if necessary, a vulcanizing agent, a vulcanization accelerator, and age resistor, a filler, a coloring agent, a flame retardant, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a rubber composition for a sealing material suitable for interposing, for example, between a vehicle tank and a body panel.

<Prior Art> Conventionally, as shown in FIG. 3, the fuel tank 1 has been placed below the trunk of a vehicle. In addition, a soundproof sheet is often laid on the top surface of the body panel 3, which is directly fixed to the body panel 3. In order to ensure the quietness of the vehicle blank area, a soundproof sheet is often laid on the top surface of the body panel 3 (Japanese Patent Laid-Open No. 59-55732
(Refer to the publication number, etc.)

<Problem that the invention seeks to solve> However, in recent years, as automobiles have become front-wheel drive (FF), propulsion shafts and final reduction gears have become unnecessary. Due to the demand for a flat surface, there is a design idea of arranging the fuel tank 1 between the rear seat and the body panel 3, as shown in FIG. Under such a design, the fuel vibrator 9 would penetrate the body panel 3;
A pipe hole 11 is bored in the body panel 3, and a sealing material is required for sound insulation and dustproofing of the pipe hole 11.

Therefore, the inventors of the present invention initially designed a tank holder with a recess 13 for the tank holder and a through hole 15 for passing the fuel vibrator 9 through the seat 1, as shown in the figure, using a conventional soundproof sheet.
7 and tested its sound insulation and dustproof properties. As a result, it was found that although the desired soundproofing properties were obtained as a characteristic of the soundproofing sheet, the sealing properties (settling resistance) for sealing gaps for a long period of time were poor, resulting in insufficient dustproofing properties. It should be noted that the sealing effect of the sealing material is required to be more severe in this design compared to the conventional design in which the fuel tank was placed under the trunk room.

SUMMARY OF THE INVENTION An object of the present invention is to provide a rubber composition for a sealing material that is suitable as a material for forming the tank holder seat 1 and has excellent sound insulation and dustproof properties.

Means for Solving the Problems> As a result of intensive studies to achieve the above object, the present inventors focused on butadiene-acrylonitrile copolymer (hereinafter referred to as rNBRJ), which has excellent fuel oil resistance. Therefore, we came up with the rubber composition for sealing materials of the present invention, which is characterized by having the following composition.

That is, a polymer blend of 60 to 80 wt% NBR and 20 to 40 wt% polyvinyl chloride (hereinafter referred to as rPVCJ)... 150 to 400 parts by weight of at least one of zinc oxide or lead oxide is added to 100 parts by weight. Department and
It consists of 5 to 30 parts by weight of plasticizer.

Detailed explanation of the method The above means will be explained in detail below.

(^) The matrix is 60-80wt% NBR and 2
Polymer blend with 0-40 wt% PvC.

If the PVC component is 20 wt% ungrooved, the ozone resistance of the sealing material will decrease, and if the PvC component exceeds 40 wt%, the compression set (settling resistance) of the sealing material will decrease, which is not preferable. B) At least one of zinc oxide and lead oxide is blended in an amount of 150 to 400 parts by weight based on 100 parts by weight of the polymer blend. These metal oxides are blended in order to increase the specific gravity of the sealing material and obtain its sound insulation properties. Sealing material (thickness: 20 m
Figure 142 shows the relationship between the specific gravity of s) and its sound insulation properties. The results of this graph are calculated by attaching the sample to the opening at the boundary between the sound receiving chamber and the sound source chamber, and assuming that the sample sound wave is constantly oscillated from the speaker in the sound source chamber. The pressure level was measured using a local octave analyzer via a microphone, and was determined as the difference in sound pressure level between the two chambers.

Through studies conducted by the present inventors, it was found that in order to achieve the desired sound insulation effect as a sealing material, the sealing material needs to have a specific gravity of 2.0 or more. % or more of zinc oxide and/or lead oxide.

Here, it is possible to use other metal oxides (including barium sulfate; the same applies hereinafter), but barium sulfate is undesirable because it reduces the elongation (Ea) of the sealing material, and titanium oxide and iron oxide are undesirable. This is undesirable as it reduces workability (see Table 2). Therefore, zinc oxide and lead oxide are suitable as fillers for making the sealing material have a desired specific gravity.

In addition, even if zinc oxide or lead oxide is used, the blending amount is 40%.
If it exceeds 0 parts by weight, the sealing material will lack tensile strength, which is undesirable (see Comparative Examples in Table 3).

(C) The plasticizer is blended in an amount of 5 to 30 parts by weight. This plasticizer is used to adjust the plasticity of the sealing material containing zinc oxide, etc., as described above, so the relationship is such that the larger the amount of zinc oxide, etc. added, the larger the amount of plasticizer added. In addition, if the blending amount is less than 5 parts by weight, this rubber composition containing zinc oxide, etc. in a higher amount than usual will cause problems such as the sealing material after vulcanization becoming too hard, resulting in insufficient sealing performance. . Also, if it exceeds 30 parts by weight, the tensile strength T
, ) decreases (see Comparative Example 8 in Table 4) and tends to set, so plasticizers that are similarly undesirable include:
Examples include adipate esters such as dibutoxyethoxyethyl adipate, dioctyl adipate, and diisodecyl adipate, phthalate esters such as dibutyl phthalate and dioctyl phthalate, and paraffin chloride, but they are compatible with polymer blends. Adipate esters are preferred because of their softening effect.

(il) In addition to the above, the rubber composition also contains a vulcanizing agent (sulfur).
and a vulcanization accelerator (TMTD, CBTS, etc.). In addition, compounding agents for two-shell rubber such as anti-aging agents, fillers, tackifiers, colorants, flame retardants, etc. are appropriately blended.

(E) Such a rubber composition is kneaded and injection molded to form the tank holder shown in FIG. Molded with sulfur.

<Effects of the Invention> As explained above, the rubber composition of the present invention has a rubber composition of 60 to
For 1001i parts of a polymer blend of 80*t% NBR and 20-40wt% PvC, 150-400 parts by weight of at least one of zinc oxide or lead oxide and 5-30 parts by weight of a plasticizer. The sealing material, which is a vulcanized product, has the desired ratio! ! (2,0) or more, and a suitable sound insulation effect is achieved. Furthermore, since the resistance to fatigue is improved, the sealing performance for the vibrator hole etc. is also ensured.

<Example> In order to confirm such effects, an example of the present invention will be described.

(a) Regarding the blend ratio of NBR and PvC, a test piece was formed using a rubber composition with the following formulation and the polymer blend ratio shown in Table 1. Vulcanization conditions: 17
0t x 10 minutes), compression set test (JIS K 6
301, conditions: 100°C x 70 hours) and ozone deterioration test (based on JIS K 6301, ozone concentration: 5011Glha, test temperature: 40°C, elongation: 20
%), and the compression set was C, 580%.
The goal is to have no cracks after 70 hours for ozone resistance. The results are shown in Table 1.

Blend of rubber composition (unit: parts by weight) Polymer blend... 100 (NBR/
PVC; variable) Stearic acid...1 ZnQ =
300 Dibutoxyethoxyethyl adipate -25 Carbon black...5 Sulfur...1.75MB
TS...3 Table 1 Ozone resistance; Cracks...△, No cracks...o1 From the results in Table 1, the PvC blend ratio is 20 to 40wt.
It can be seen that in each of Examples 1 to 3, which are vulcanized products, the sealing materials have suitable resistance to settling (compression set) and ozone resistance. On the other hand, the blend ratio of PvC is 40
Comparative Example 2, in which the blend ratio exceeds 20 wt%, has poor stagnation resistance, while Comparative Example 1, in which the blend ratio is less than 20 wt%, has poor ozone resistance.

(b) Regarding the selection of metal oxides, the sealing material, which is a vulcanized product of a rubber composition, is
), metal oxides in the amounts shown in Table 's2 were blended into the rubber composition of the following formulation.

Blend of rubber composition (unit: parts by weight) Polymer blend ・Touge 10100 (PVC
H30%) Stearic acid 1 Metal oxide Variable dibutoxyethoxyethyl adipate 5 Sulfur
... 1.75 Vulcanization accelerator
... 3 A test piece was formed from the rubber composition, and the following test items were investigated under vulcanization conditions (170° C. x 10 minutes).

■Kneading processability.

■Normal physical properties (hardness Hs; JIS A), tensile strength Ta), elongation (Ea)) are JIS K 6
Pursuant to Law 301. Note that a No. 3 dumbbell was used as the test piece.

In addition, each target value of the normal physical property test is HM70±10, T11
≧80, E, ≧250.

The results are shown in Table 2 on the next page.

From the results in Table 2, titanium oxide (Comparative Example 5) and iron oxide (
Comparative Example 6) cannot be kneaded into a polymer blend,
It can be seen that with barium sulfate (Comparative Example 4), the normal physical properties of the amount of vulcanization deviate significantly from the target value. In addition, in Comparative Example 3, since zinc oxide was blended in a predetermined amount (400 parts by weight) or more, the normal physical properties were insufficient. It is shown here to show the results of kneading processability. Of course, desired normal physical properties can be obtained by changing the blend of zinc oxide (see Example 11 in Table 4).

With lead oxide (fourth example), suitable normal state physical properties were obtained.

Table 2 In the table, the numbers in parentheses deviate from the target value.

(C) Concerning the blending amount of zinc oxide, lead oxide, and plasticizer, Table 3 shows suitable blending examples of lead oxide and plasticizer, and Table 4 shows suitable blending examples of zinc oxide and plasticizer. Indicated.

A test piece was molded from the rubber composition of each compounding example under vulcanization conditions: 170°C x 10 minutes), and normal state physical properties (H, TBsE%, compression set and ozone Various deterioration tests were conducted.The results are shown in the respective tables on the following pages.

From the results in Table 3.4, the amount of zinc oxide or lead oxide is 150 to 400 parts by weight, and the amount of plasticizer is 5 to 400 parts by weight.
It turns out that 30 parts by weight is suitable. The same is expected when zinc oxide and lead oxide are used together.

In addition, the amount of the metal oxide or the plasticizer is 400! It can be seen that when 30 parts by weight (see Comparative Example 7) and 30 parts by weight (Comparative Example 8) are added, the tensile strength (T3) does not reach the target value, which is not preferable.

Table 3 In the table, the numbers in parentheses deviate from the target value.

Table 4 In the table, the numbers in parentheses deviate from the target value.

[Brief explanation of drawings]

Fig. 1 is a diagram showing an example of the use of a sealing material which is a vulcanized molded product of the rubber composition of the present invention, and Fig. 2 is a graph showing the relationship between the specific gravity of the sealing material, which is the amount of rubber vulcanization, and sound insulation properties. FIG. 3 is a diagram showing the position of a conventionally designed fuel tank 1. ! ...Fuel tank, 3.Body panel, 17.Tank holder is seat. Patent application Toyoda Gosei Co., Ltd.

Claims (1)

[Claims] 150 to 400 parts by weight of at least one of zinc oxide or lead oxide is added to 100 parts by weight of a polymer blend of 60 to 80 wt% of butadiene-acrylonitrile copolymer and 20 to 40 wt% of polyvinyl chloride. A rubber composition for a sealing material, comprising: parts by weight, and 5 to 30 parts by weight of a plasticizer.