JPS58131138A - Adhesion inhibitor of combustion residue - Google Patents

Abstract

PURPOSE:To obtain the adhesion inhibitor of combustion residue capable of removing tar or soot on the surface of a sound absorbing base material rapidly and perfectly, by combining a solid acid catalyst with an adhesion inhibitor consisting of graphite fluoride and a heat resistant binder. CONSTITUTION:The adhesion inhibitor of combustion residue used in coating the surface of the sound absorbing material of an exhaust muffler apparatus for an internal combustion engine is constituted by containing and dispersing graphite fluoride low in surface energy in a heat resistant binder along with a solid acid catalyst. When the surface of the aforementioned sound absorbing material is coated with this adhesion inhibitor, the polymerization of tar is suppressed to smoothly blow off almost all tar from said surface and the adhesion of tar or soot can be availably prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an agent for preventing the adhesion of combustion residues, which is applied to sound absorbing materials of exhaust silencing devices for internal combustion engines.

For example, sound absorbing materials used in exhaust silencers for internal combustion engines include so-called porous materials in the form of fibers, foams, particles, etc., such as glass wool, porous ceramics, and porous metals. However, if these materials are used as sound-absorbing materials as they are, soot, which is the residual combustion of fuel such as gasoline, will enter the surface and inside the porous material through the casing during internal combustion engine-related rotations, and will adhere for a relatively short period of time. Clogged inside -49
As a result, the sound absorption performance deteriorates, the noise becomes intensified, and the fuel efficiency of the internal combustion engine is also adversely affected, which are unavoidable problems.

The inventors conducted various studies to find out why soot adheres to the surface of sound-absorbing materials, and found that the main cause was water (steam) produced by combustion of gasoline or a tar-like substance that was the residual liquid after combustion. It turned out to be. In other words, the soot emitted from the engine exhaust port has an average particle size of &
Although the particles are about 100 A, the adhesion force (surface energy) is large due to the water or tar attached to them or to the surface of the sound absorbing material, causing cracks on the entire surface and inside of the sound absorbing material. It's so sweet to be attached to her. Therefore, in order to prevent soot from adhering to
It has been found that it is sufficient to coat the surface of the sound absorbing material with a substance having low surface energy to prevent it from adhering to the surface and from entering the interior. Therefore, the inventors coated the surface of sound-absorbing materials with various substances with low surface energy as adhesion prevention agents for residual combustion bath, and when they actually used them as exhaust silencers for internal combustion engines, they found that they If the exhaust muffler is made of organic matter, the surface temperature of the sound absorbing material in the exhaust muffler will be 1
It was found that the temperature ranged from 50 to 500°C, causing decomposition and loss of low surface energy properties. Therefore, similar studies were conducted after inorganic substances such as graphite and molybdenum disulfide were dispersed and adhered to the surface of the sound absorbing material as solid lubricity inhibitors.
Due to the increased leakage, the surface energy of the decomposed particles increases, causing soot to adhere to the surface. Some of them were lenient because they significantly hindered performance, while others were lenient because they introduced new flaws.

In order to solve this problem, the present inventors devised the use of buttomized graphite, which is a low surface energy material, as the persimmon adhesion prevention agent.

Buttonized graphite is a fine particulate inorganic polymer made up of covalent bonds between fluorine and carbon. Its properties include low surface energy and a small coefficient of friction, so it is used in solid lubricants and the like. However, that +aI! However, due to its low surface energy, it is not easy to attach to the surface of materials, and currently it is dispersed in small amounts in greases, etc. It is attached to the metal-like surface by eutectoid plating with metals such as JP, Ni, etc. However, when applied to an adherend, a substance dispersed in grease etc. has poor heat resistance and adhesion, and in the case of eutectoid plating, the adherend must be metal, so it cannot be applied. Gender was narrow. The inventors have constructed an anti-adhesion agent for combustion residue by dispersing atomized graphite fine particles in a heat-resistant binder, and when this is used by applying it to the surface of a sound-absorbing base material of an internal combustion engine, for example, 1li1
It was discovered that the action of the buttomized graphite dispersed in the porous film of the thermal binder makes it difficult for soot and water (steam), which are the residues of fuel combustion, to adhere to the material.

However, although the structure described above has excellent adhesion and longevity, it is difficult to quickly and completely remove tar, soot, etc. that have once adhered to the surface of the sound-absorbing substrate, and it is not sufficient as an adhesion prevention agent for combustion residue. It couldn't be called anything.

The present invention provides a new combustion residue adhesion prevention agent that does not have any of the above-mentioned disadvantages and can significantly suppress soot adhesion to sound absorbing materials. That is, the combustion residue adhesion prevention agent according to the present invention is characterized by using bubbly graphite particles as a low surface energy substance, and containing and dispersing a solid acid catalyst in a heat-resistant binder together with the bubbly graphite. .

Here, a steel plate on which AJ plating has been applied is prepared, and after heating the steel plate to 250°C, 10y of tar is dropped onto the surface of the steel plate. When the surface of the steel plate is exposed, it is difficult to blow off the tar from the surface of the steel plate when a second wind is applied, and most of the tar becomes attached. On the other hand, when the surface of the steel plate is coated with particles of graphite dispersed in a resistant binder, the tar is blown off more than in the case described above, but the -Hs tar is polymerized. Since the adhesion force is strengthened by X, the tar remains attached to the steel plate.

However, it has been found that when the surface of the steel plate is coated with the combustion residue adhesion prevention agent according to the present invention, the polymerization of tar is suppressed and most of the tar is smoothly blown away from the steel plate. Ta.

Therefore, it can be seen that the combustion residue adhesion prevention agent according to the present invention can effectively inhibit the adhesion of tar, soot, etc. simply by applying it to the surface of a sound-absorbing substrate or the like.

Hereinafter, the present invention will be described in detail based on examples.

[Example 1] Ni-C used as a sound-absorbing base material of an exhaust silencer for an internal combustion engine to which a combustion residue adhesion prevention agent is applied.
A foamed metal porous body made of r alloy was prepared. Silicone resin dissolved in thinner is used as a heat-resistant binder, and a dispersant (
(surfactant) and some additives to make 50% by weight, in which 25% by weight of bubbly graphite and 25% by weight of a solid acid catalyst such as activated alumina are dispersed. was applied to the surface of the porous body by spraying as a combustion residue adhesion prevention agent according to the present invention, and heated at 80°C.
After preliminarily baking at 250°C for 20 minutes, the sample was baked at 250°C for 30 minutes. As a result, a sound absorbing material as shown in the enlarged cross-sectional view of FIG. 1 was manufactured. In Fig. 1, (1) is the skeleton of the porous body, (2) is the butt-filled graphite particles, and (3) is the heat-resistant structure containing and dispersing the butt-filled graphite particles (2) and the acid catalyst (5). The cured product of the adhesive binder constitutes the combustion/residual adhesion prevention agent M according to the present invention. (4) are the pores (holes) of the porous body. The combustion residue adhesion prevention agent M according to the present invention is infiltrated not only onto the surface of the porous body but also into the internal pores (4) as shown in FIG. 1 by the above coating operation.

Using the sound absorbing material constructed in this way, we investigated the sound absorption coefficient, soot adhesion, and the resulting deterioration of sound deadening performance over time, while comparing it with a metal porous material that was not subjected to the above-mentioned treatment.

FIG. 2 shows the normal incidence sound absorption coefficient measured under the same conditions by the in-pipe method (JISA1405). The curve a shows the characteristics of the sound absorbing material coated with the combustion residue adhesion prevention material A1 of the present invention, and the curve a shows the characteristics of the sound absorbing material made only of metal porous bodies.

From FIG. 2, it can be seen that the sound absorbing material coated with the combustion residue adhesion prevention agent of the present invention has a significantly higher sound absorption coefficient than the sound absorbing material made of only a metal porous body. This is a cured product of a heat-resistant binder containing and dispersing atomized graphite and a solid acid catalyst. This is believed to be because the combustion residue adhesion prevention agent of the present invention is essentially porous and room air can flow through it, so that sonic energy is also absorbed and attenuated.

Therefore, the two types of sound absorbing materials mentioned above were formed into a cylindrical shape, an exhaust silencing device was constructed as shown in Figure 3, and it was installed in a commercially available domestically produced passenger car (displacement 1.600 cc). After actual driving, the silencing performance was measured according to JISD1616 and compared with the initial value before actual driving. In FIG. 3, 0υ is a housing constituting the exhaust noise muffling device, 64 is the population of exhaust gas, character is an exhaust gas passage, (b) is a sound absorbing material, and 0 is an exhaust gas outlet pipe. Figure 4 shows the frequency characteristics of the silencing performance. Curves C1 and C2 are the initial and after actual running characteristics, respectively, when using a sound absorbing material coated with the combustion residue adhesion/adhesion prevention ax according to the present invention, and curves d] and d2 are for the porous metal material only. These are the initial characteristics and the characteristics after actual driving when using sound absorbing materials. As can be seen from Figure 4, the sound absorbing material coated with the combustion residue adhesion prevention agent of the present invention not only has good initial silencing performance, but also has almost the same initial performance after 10,000 actual runs. On the other hand, when using a sound absorbing material made of only porous metal, the sound deadening performance significantly deteriorated in all frequency bands after actual driving. After measuring the silencing performance, both sound absorbing materials were removed and visually observed, and it was found that the sound absorbing materials coated with the combustion residue adhesion prevention agent of this invention were almost as clean as the initial state. In addition to demonstrating the excellent soot adhesion prevention effect of carbonized graphite, solid acid catalyst particles are activated by the exhaust gas temperature, causing tar-forming components in the exhaust gas to scatter and adhere to the solid acid catalyst particles. , prevents oxidative polymerization (polymerization) on the surface of the sound absorbing material, and lowers the molecular weight of its components to make them easier to vaporize, so it automatically reacts to the exhaust gas temperature without becoming tar and adhering to it. It has also been demonstrated that it can be vaporized (purified). On the other hand, those with only porous metal have soot, yellow-green corrosion, and a large amount of products adhering to the entire surface, resulting in serious clogging.
was waking up. That is, the sound absorbing material coated with the combustion residue adhesion prevention agent of the present invention has a soot adhesion inhibiting effect, and at the same time, the tar-forming component is prevented by containing the atomized graphite and solid acid catalyst in the heat-resistant binder. It has been revealed that it can also inhibit the oxidative polymerization of , and also has a remarkable corrosion-inhibiting effect. In the sound absorbing material coated with the combustion residue adhesion prevention agent of the present invention, the above adhesion prevention agent did not peel or crack at all even after actual running. It was also revealed that f4J has excellent adhesive properties and has a long life.

The above-mentioned solid acid catalyst is a substance that has the function of releasing protons (H) or accepting pairs of electrons.The above-mentioned catalytic function is used in the petrochemical industry to treat heavy oil with a high boiling point (high temperature vaporized substance). This process is well known as cranking, in which oil is catalytically cracked to produce light oil with a low boiling point (low-temperature vaporized substance).

[Example 2] SiO□-A used as a sound-absorbing base material of an exhaust silencer for an internal combustion engine is coated with a combustion residue adhesion prevention agent.
]203 thread ceramic porous body was prepared. In the same manner as in Example 1, the agglomerated graphite fine particles and a solid acid catalyst such as activated alumina were mixed with monobasic aluminum phosphate (aluminum phosphate). A sound absorbing material was manufactured by coating the surface of the porous body with the combustion residue adhesion prevention agent of the present invention, which is contained and dispersed together with a dispersant and additives in a varnishing binder. This sound absorbing material and the same ceramic porous body as above, but without the adhesion prevention agent applied thereto, were also investigated for sound absorption coefficient and soot adhesion prevention property in exactly the same manner as in Example 1. As a result, it was found that the sound absorbing material coated with the combustion residue adhesion prevention agent according to the present invention showed the same characteristics as those of Example 1 in both the sound absorption coefficient and the silencing performance due to the prevention of clogging and breakage during actual vehicle running. It was found that it had almost the same excellent characteristics as the case shown in FIGS.

Here, talking about the ratio of the above-mentioned buttomized graphite, heat-resistant binder, and solid acid catalyst, if the buttomized graphite is less than 1% by weight, its function is hardly exhibited;
If it exceeds this value, it will be difficult to form a film, and even if a film is formed, it will be brittle. In addition, the heat-resistant binder is 10
If it is less than 70% by weight, it will not have the ability to bind other particles such as abutted graphite, and if it exceeds 70% by weight, it will no longer have the ability to bind other particles. Solid acid catalyst is 10% by weight
If it is less than 80% by weight, its function will not be performed effectively.
Even if the temperature exceeds 100%, problems such as difficulty in forming a film will occur.

Therefore, it is necessary to set the content of the abutted graphite, the heat-resistant binder, and the solid acid catalyst within the ranges of 1 to 60% by weight, 10 to 70% by weight, and 10 to 80% by weight, respectively, and preferably The values shown in the above examples are 25% by weight, 50% by weight, and 25% by weight, respectively.

In each of the above Examples, only a solid acid catalyst was used as a catalyst, but at least one of a reducing agent and an alkaline agent or a lower oxidation catalyst may be selectively added to this solid acid catalyst.

By the way, in this invention, the heat-resistant binder containing and dispersing the abutted graphite fine particles has a surface temperature of 150 to 500°C of the sound absorbing material in the exhaust silencing device of an internal combustion engine.
Any inorganic binder that has a heat resistance temperature above the above can be used. In our study, we added additives (to improve adhesion and crack prevention properties) to glassy frit, metal phosphate, metal silicate, colloidal silica, colloidal alumina, and silicone resin. The results were better.

Well, the solid acid catalyst used in this episode 811 is:
In addition to those described in the Examples, there are silica alumina, vanadium pentoxide, alumina boria, bubbly, synthetic biolite, acid clay, and the like.

The combustion residue adhesion prevention agent according to the present invention is intended to be used in an exhaust silencing device for an internal combustion engine, but depending on how it is used, it may also be used in other equipment such as combustion equipment.

As described above, the combustion residue adhesion prevention agent of Source 1, which is made by containing a solid acid catalyst together with atomized graphite in a heat-resistant binder, can be applied, for example, to the sound absorbing material of an exhaust silencer for an internal combustion engine. When used, it prevents the deterioration of sound deadening performance caused by soot clogging and maintains the initial good sound deadening performance, and when applied to porous metal objects, it provides significant corrosion prevention. Effects can be obtained. therefore,
Since it can ensure high performance and long life, it can be widely used in exhaust silencing devices for internal combustion engines such as automobiles.

[Brief explanation of drawings]

FIG. 1 is an enlarged view showing a structure in which a combustion residue adhesion prevention agent according to the present invention is applied to a sound absorbing material, FIGS. 2 and 4 are characteristic diagrams showing the performance of the sound absorbing material in FIG. 1, and FIG. The figure is a sectional view showing an example of application of the sound absorbing material shown in FIG. 1. (2)...buttonized graphite, (3)...heat-resistant binder,
(5)...Solid acid catalyst. Note that the same reference numerals in the figures indicate the same or corresponding parts. Agent Makoto Kuzuno - (1 other person) Procedural amendment (formality) Commissioner of the Japan Patent Office 1, Indication of case Patent application No. 14488, No. 57-14488
No. 2, Name of the invention Combustion residue adhesion prevention agent 3. Person making the amendment (]) 6. Drawing subject to the amendment 7. Contents of the amendment (1) Attached is an engraving describing Figure 1 (no changes in content) ) Resubmit. Above (2)

Claims (1)

[Claims] (]) An anti-adhesion agent for combustion residual liquid, characterized in that a homogeneous contact is contained and dispersed in a heat-resistant binder together with agglomerated graphite.