JP2967547B2 - Silica-based reinforcing filler - Google Patents

Description

The present invention relates to a treatment with an acetylene compound which exhibits excellent dispersibility when added to natural rubber or synthetic rubber and gives high vulcanizate a high mechanical strength. To a silica-based reinforcing filler.

[Prior Art] Carbon black has been most widely used as a reinforcing filler for natural rubber or synthetic rubber. This is because lipophilic carbon black is familiar with natural rubber or synthetic rubber,
This is because the reinforcing effect is large.

On the other hand, fine silica particles, which are silica-based fillers, are more resistant to heat aging, tear resistance,
It has the characteristics of excellent resistance to flex cracking and adhesion, and it can be colored freely, but because of the hydrophilic silanol groups on the particle surface, it does not fit well with synthetic rubber or natural rubber except silicone rubber, and poor dispersion. As a result, the viscosity of the rubber compound is increased, and the processability and the physical properties of the vulcanized product are greatly reduced.

In order to improve this, a method of treating the silica surface with alcohols such as polyethylene glycol, amines, higher fatty acids, etc. has conventionally been proposed. Poor effect, adversely affecting physical properties of vulcanizate. Further, the method of treating with an organosilicon compound such as silane, organopolysiloxane, or organopolysilazane improves the dispersing effect, but makes the treated silica-based filler extremely expensive and impractical.

[Problems to be Solved by the Invention] In view of the above situation, the present invention is easily and inexpensively manufactured, has good dispersibility in natural rubber and synthetic rubber, and has excellent properties of these vulcanized products. The purpose of the present invention is to provide a silica-based reinforcing filler.

[Means for Solving the Problems] The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, by treating with a certain acetylene compound, a silica-based material having remarkably improved dispersibility in rubber has been obtained. A filler is obtained, and it is found that if this silica-based filler is blended, a rubber compound having a low viscosity can be obtained, and good processability and excellent vulcanization properties can be obtained, and the type and treatment of the acetylene compound can be obtained. Further investigations were made on the amounts to complete the present invention.

That is, the silica-based reinforcing filler of the present invention is a silica-based reinforcing filler having a specific surface area of at least 30 m ² / g,
It is characterized by being treated with 0.1 to 20 parts by weight of acetylene alcohol or its alkylene oxide adduct with respect to 100 parts by weight.

 Hereinafter, the present invention will be described in detail.

The silica-based filler used in the present invention is required to be fine particles having a specific surface area of at least 30 m ² / g. When the specific surface area is less than this, physical properties of the vulcanized product become insufficient.
Examples of such silica-based fillers include aerosil, a fumed silica produced by a dry method represented by the trade name of Cabosil, precipitated silica synthesized by a wet method from alkyl silicate and sodium silicate, magnesium silicate, calcium silicate And the like.

Next, acetylene alcohol or an alkylene oxide adduct thereof for treating the silica-based filler is a compound having a carbon-carbon triple bond and an alcoholic hydroxyl group in the molecule or an alkylene oxide in the alcoholic hydroxyl group of the compound. It is an added compound.

However, among these compounds, the general formula (Here, R ¹ represents an alkyl group having 1 to 8 carbon atoms, A represents an alkylene glycol residue having 2 to 3 carbon atoms, and R ¹ and A in one molecule are different even if they are the same. And x and y each represent an integer of 0 to 25).

Preferred examples of the compound represented by the above general formula include 3-methyl-1-butyn-3-ol, 3,5-dimethyl-1-hexyn-3-ol, and 3,5-
Ethylene oxide adduct of dimethyl-1-hexyn-3-ol, 2,5-dimethyl-3-hexyne-2,5-diol, 2,4,7,9-tetramethyl-5-decyne-4,7-diol , Ethylene oxide adduct of 2,4,7,9-tetramethyl-5-decyne-4,7-diol, propylene oxide addition of 2,4,7,9-tetramethyl-5-decyne-4,7-diol Object, etc. are exemplified. These acetylene compounds can be obtained from commercial products (manufactured by Air Products & Chemicals Incorporated, USA, sold by Nissin Chemical Co., Ltd., trade names: Olfin or Surfynol).

Silica-based fillers treated with such compounds exhibit excellent wetting and dispersing effects on rubber, but this is because this acetylene compound has a unique molecular structure having an acetylene bond and a hydroxyl group. It is considered that the —OH group or —O— group bonded to the carbon atom adjacent to the triple bond greatly increases the electron density. In particular, silica-based fillers treated with a symmetrical acetylene compound represented by the general formula (II) exhibit excellent wetting and dispersing effects on rubber, but this is because the dispersion center is strongly polarized. It is thought to be.

If the values of x and y in the general formulas (I) and (II) exceed 25, the number of moles of alkylene oxide added becomes too large, and the relative concentration of the specific structure portion containing the acetylene triple bond is considered to decrease. However, it is not practical because the wetting / dispersing effect is diluted.

If necessary, two or more acetylene alcohols or alkylene oxide adducts can be used in combination.

When the treatment amount of acetylene alcohol or its alkylene oxide adduct is less than 0.1 part by weight with respect to 100 parts by weight of the above-mentioned silica-based filler, the effect of dispersing in rubber is small, and therefore, the Mooney viscosity of the rubber compound is high and the roll processability is high. Poor composition. Further, even if the treatment is carried out in an amount exceeding 20 parts by weight, no improvement in processability is observed. Therefore 0.1
It is assumed that the silica is processed in the range of up to 20 parts by weight.

The treatment of the silica-based filler with acetylene alcohol or an alkylene oxide adduct thereof can be performed by a known silica surface treatment method. For example,
As described in Japanese Patent No. 17049, a method in which a silica-based filler and a processing agent are reacted in a processing chamber comprising an upright tubular furnace by a co-current method of continuously proceeding, described in JP-B-60-6379. A method of contacting a silica-based filler and a treating agent at a relatively low temperature, and then performing a heat treatment at a high temperature,
And the like.

In addition, this treatment adds acetylene alcohol or its alkylene oxide adduct to the wet silica slurry,
It can also be carried out by mixing, filtering, washing with water, dehydrating and drying. In this method, bubbles adhering to the silica surface were promptly removed, and it was found that the filtration and dehydration steps had a significant time reduction effect. This is thought to be due to the wetting effect of the treatment agent by the acetylene compound.

The silica-based reinforcing filler of the present invention is a natural rubber and various synthetic rubbers such as styrene-butadiene rubber, acrylonitrile-butadiene rubber, hydrogenated acrylonitrile-butadiene rubber, butadiene rubber, isoprene rubber, chloroprene rubber, ethylene-propylene rubber, Ethylene-
It can be used for propylene-diene rubber, acrylic rubber, ethylene-acrylate rubber, ethylene-vinyl acetate rubber, urethane rubber, polysulfide rubber, chlorosulfonated polyethylene rubber, chlorinated polyethylene rubber, fluoro rubber, epichlorohydrin rubber and the like.

Although not as common as for rubber, silica-based reinforcing fillers are used for the purpose of improving the processability and physical properties of synthetic resins such as vinyl chloride resin, polyethylene, polypropylene, epoxy resin, and polyester resin. However, in this case, since a large shearing force such as that of rubber does not act, it takes a long time to disperse the silica-based reinforcing filler having a large cohesive force, and still causes poor dispersion or compounding. There was a problem that the viscosity of the product was extremely large and molding failure occurred. However, it has been found that the silica-based reinforcing filler treated with the acetylene compound of the present invention has good dispersibility even in a synthetic resin,
It has become possible to improve the conventional defect caused by poor dispersion and to impart the characteristics of a silica-based filler.

[Example] Next, the present invention will be described with reference to examples. The parts in the composition represent parts by weight, and the physical properties of the vulcanized sheet obtained by vulcanizing the composition were measured according to the method of JIS K-6301.

Example 1 While stirring 100 parts of wet silica, Nipsil LP (trade name, manufactured by Nippon Silica Co., Ltd.) having a specific surface area of 230 m ² / g, 2,4,
3,9-tetramethyl-5-decine-4,7-diol ethylene oxide average adduct of 3.5 mol (Nissin Chemical Industry Co., Ltd.)
Sale, brand name Surfynol 440) 25 parts, methanol 25
After mixing and adding the solution consisting of
To remove the adsorbed water of methanol and silica.
The mixture was kept at 0 ° C. for 1 hour to obtain a silica-based filler (A-1).

Next, 100 parts of an acrylic rubber, RV-1240 (trade name, manufactured by Nissin Chemical Industry Co., Ltd.) are wound around a roll, 1 part of stearic acid, and 50 parts of the silica-based filler (A-1) obtained above.
And 2 parts of Nowgard 445 (trade name, manufactured by Uniroyal Co., Ltd.) were added and sufficiently kneaded, and then heat-treated at a roll temperature of 130 ° C. for 10 minutes to remove water in the silica. After cooling this formulation, the Mooney viscosity [ML _{1 + 4} (100
° C)].

To the composition obtained above, for 100 parts of acrylic rubber,
1.5 parts of trithiocyanuric acid, 5 parts of magnesium oxide,
1.5 parts of zinc dimethyldithiocarbamate was added on a roll, kneaded well, and the resulting mixture was press-vulcanized at 165 ° C. for 12 minutes, and further vulcanized in an oven at 175 ° C. for 8 hours to a thickness of 2 mm. To obtain a vulcanized sheet.

Table 2 shows the Mooney viscosity and the properties of the vulcanized sheet.

Examples 2 to 8, Comparative Examples 1 and 2 In the same manner as in Example 1, silica was treated with an acetylene compound according to the formulation shown in Table 1 to obtain a silica-based filler (A-2).
To (A-8).

Next, blending was carried out in the same manner as in Example 1 with the formulation shown in Table 2, and Mooney viscosity was measured, vulcanized, and the properties of the vulcanized sheet were measured in the same manner. Table 2 shows the Mooney viscosity and the properties of the vulcanized sheet.

Examples 9 and 10, Comparative Examples 3 and 4 Ethylene-propylene-diene elastomer (EPD
For M) and NBR, the formulation shown in Table 3 was carried out in the same manner as in Example 1 using the silica-based filler (A-2) obtained in Example 2, and the Mooney viscosity of the formulation was similarly measured. It was measured. The resulting composition was press-vulcanized at 150 ° C. for 15 minutes, and the properties of the vulcanized sheet were measured. Table 3 shows the Mooney viscosity and the properties of the vulcanized sheet.

Examples 11 to 14, Comparative Example 5 Surfynol 440 (supra) was added to a slurry obtained by stirring 80 parts of water and Nipsil LP (supra) at a ratio of 20 minutes with an agitator for 30 minutes. Add as many copies as shown, then add 3
Stirred for 0 minutes.

The obtained slurry was weighed in an amount of 150 cc, placed in a filtration funnel (filtration area: 33.2 cm ² ) loaded with No. 2 qualitative filter paper (thickness: 0.8 mm), and vacuum-filtered at a vacuum of 700 to 730 mmHg.

The time until the water did not fall was measured, and is shown in Table 4 as the filtration time.

For comparison, the same measurement was performed without adding Surfynol 400, and the results are shown in Table 4.

[Effects of the Invention] By blending the silica-based reinforcing filler of the present invention into rubber, Mooney viscosity is significantly reduced, fluidity is improved, complicated molding is enabled, and roll processability is improved. And the physical properties of the vulcanized rubber are improved.

Further, the filterability of the water slurry when treating the silica-based filler is remarkably improved, and the filtration time is greatly reduced.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-3-111438 (JP, A) JP-A-2-117911 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C09C 3/08 C09C 1/30 C08K 3/36 C08K 9/04

Claims (2)

(57) [Claims] 1. A silica-based reinforcing filler having a specific surface area of at least 30 m ² / g, based on 100 parts by weight of acetylene alcohol or an alkylene oxide adduct thereof of 0.1 to 2 parts by weight.
A silica-based reinforcing filler treated with 0 parts by weight. 2. An acetylene alcohol or an alkylene oxide adduct thereof, having the general formula: (Here, R ¹ represents an alkyl group having 1 to 8 carbon atoms, A represents an alkylene glycol residue having 2 to 3 carbon atoms, and R ¹ and A in one molecule are different even if they are the same. Wherein x and y each represent an integer of 0 to 25).