KR102024115B1 - Method for making diesel particulate filter having low thermal expansion coefficient and diesel particulate filter comprising the same - Google Patents

Abstract

The present invention relates to a binder composition for a diesel particle filter and a diesel particle filter including the same, and more particularly, to a honeycomb structure having excellent mechanical properties, including less than 0.3% by weight of sodium chloride (NaCl) relative to the weight of the total binder composition. It shows an excellent effect of providing a diesel particle filter.

Description

Method for making diesel particulate filter having low thermal expansion coefficient and diesel particulate filter comprising the same}

The present invention relates to a method for producing a diesel particle filter having an improved coefficient of thermal expansion and a diesel particle filter produced through the same, and more particularly, to a diesel particulate filter (DPF) containing less than 0.3% by weight of sodium chloride (NaCl). A binder composition for) and a filter comprising the same.

Diesel particles contained in the exhaust gas of automobiles are carbon-based particulates. When the engine of a vehicle is rotated at high speed, the exhaust gas is relatively high and diesel particles are naturally burned. When the engine rotates at a low speed, combustion of diesel particles is not performed well, and it is released into the atmosphere together with the exhaust gas to pollute the atmosphere.

As described above, a diesel particle filter made of a ceramic material is installed in an exhaust pipe through which exhaust gas is discharged in order to prevent air pollution due to diesel particles, thereby suppressing the emission of diesel particles into the air.

Various systems using cyclic thermal incineration or continuous regeneration using catalysts have been tried to reduce diesel vehicle emissions. However, in terms of economics, continuous regeneration methods using oxidation catalysts are considered to be the most effective. In particular, the combination with the filter can achieve high removal efficiency for particulate contaminants.

Korean Patent Publication No. 10-2012-0092979, which is a technique for bonding to a filter or a support, includes a palladium-fixed powder manufacturing step of preparing a support powder having palladium fixed thereon, a support powder having palladium powder fixed thereto, distilled water and a platinum solution. Pre-mixing step of preparing a platinum palladium premix by mixing the mixture, the nitric acid addition step of adding nitric acid to the mixture consisting of the pre-mixture and platinum solution described above, impregnating and stirring the catalyst support in the mixture after the nitric acid addition step A method for preparing a diesel vehicle catalyst using platinum and palladium is disclosed, which includes a firing step of firing a catalyst mixture that has undergone an impregnation stirring step and an impregnation stirring step. In addition to the above technology, Korean Patent Publication No. 10-2013 -0114401 applies a diesel oxidation catalyst mixture to the exhaust gas outlet line of a diesel particle filter. First, the diesel particulate filter is impregnated with the diesel oxidation catalyst mixture, and the diesel particulate filter is denitrified oxide catalyst mixture so that the denitrification oxide catalyst mixture is applied to the exhaust gas inlet line of the diesel particle filter. "Diesel oxidation catalyst and denitrification catalyst are coated with a second impregnation step of impregnation, a drying step of drying the diesel particle filter subjected to the second impregnation step, and a firing step of firing the diesel particle filter subjected to the drying step. Method for producing a diesel particle filter is disclosed.

However, the conventional diesel particle filter has a problem that the mechanical properties such as cracks are deteriorated in the process of filtering the high temperature exhaust gas for a long time due to the high coefficient of thermal expansion, thereby eliminating the problem of such mechanical property deterioration. There has been a need for the manufacture of binders that allow the provision of connecting filters.

Therefore, the technical problem to be solved in the present invention has a low coefficient of thermal expansion because it contains almost no impurities that can increase the coefficient of thermal expansion, so that even if the high-temperature exhaust gas is filtered for a long period of time deterioration of mechanical properties such as cracking It is to provide a binder composition for diesel particle filter does not occur.

An object of the present invention as described above comprises 5 to 10 parts by weight of a binder consisting of a cellulose-based component compared to 100 parts by weight of cordierite starting material as a binder composition for improving the thermal expansion characteristics of the diesel particle filter, and 30 to 40 parts by weight of an additive However, it is achieved by providing a binder composition for a diesel particle filter, characterized in that the sodium chloride in the binder is contained in less than 0.3% by weight relative to the total composition weight. According to a preferred feature of the present invention, the sodium chloride is contained as an impurity in the cellulose component, more preferably 0.2% by weight relative to the total composition weight.

 According to a preferred feature of the invention, the cellulose component is to be made of one or more selected from the group consisting of hydroxypropylmethyl cellulose and methyl cellulose.

Although the binder composition for the diesel particle filter according to the present invention has a low thermal expansion coefficient because of the very low sodium chloride component contained in the cellulose component despite the use of the cellulose component, it provides an excellent diesel particle filter having excellent thermal properties Effect.

1 is a graph showing the results of the thermal expansion coefficient (CTE) change test of the diesel particulate filter according to the NaCl content in the binder.

Hereinafter, the present invention will be described in more detail.

In one embodiment, the present invention relates to a binder composition for diesel particle filters, characterized in that the content of sodium chloride relative to the total binder weight is less than 0.3% by weight relative to the total binder composition weight.

In a specific embodiment, the binder composition for a diesel particle filter according to the present invention may include a binder and an additive composed of a cellulose-based component, the content of sodium chloride relative to the total composition weight of less than 0.3% by weight, preferably less than 0.2% by weight Characterized in that it is included. The cellulose component is composed of at least one selected from the group consisting of hydroxypropyl methyl cellulose and methyl cellulose. The cellulose component exhibits excellent extrudability and excellent extrudability even at low pressure during extrusion of a diesel particle filter. It serves to strongly bind the components added for diesel particle filter extrusion, such as cordierite starting material, walnut, graphite and the like. In a preferred embodiment, the cellulosic component may be included in 5 to 10 parts by weight based on the cordierite starting material included in the diesel particle filter.

Cellulose-based components such as hydroxypropyl methyl cellulose and methyl cellulose are obtained by a process of extracting a piece of wood such as wood chips with a thermal alkali called a pulp process, wherein the alkali used is mainly NaOH. As a result, about 1% by weight of sodium chloride is contained in cellulose-based components such as hydroxypropylmethylcellulose and methylcellulose, which are final products.

However, the present inventors have confirmed that the thermal expansion coefficient of the diesel particulate filter is remarkably changed depending on the content of sodium chloride included in the binder as impurities of the cellulose component.

Specifically, the binder composition for diesel particle filter according to the present invention preferably contains less than 0.3% by weight of sodium chloride, preferably less than 0.2% of the total composition. Preferably, such a cellulose component having a low content of sodium chloride may be purchased and used as a commercial product that satisfies the above sodium chloride content conditions, or may be obtained by lowering the content of sodium chloride through a separate process.

In the binder composition for a diesel particle filter according to the present invention, the additive may be used without limitation as long as the additive can be included in the binder composition, for example, may include triethylene glycol, wax, and the like. The triethylene glycol may improve the flexibility of the binder composed of the cellulose component, and may play a role of improving the efficiency of the extrusion process in the extrusion molding of the diesel particle filter. In a preferred embodiment, the additive may be included in 30 to 40 parts by weight relative to 100 parts by weight of cordierite starting material which is a diesel particle filter component.

In addition, the binder composition may further include an additional binder in addition to the binder made of a cellulose component. The additional binder may be at least one selected from the group consisting of known inorganic binders, for example, clay, feldspar, alumina, silica-alumina, silica, and magnesium aluminum-silicate.

In a preferred embodiment, the binder for the diesel particle filter according to the present invention preferably has a viscosity of 3500 ~ 30,000cps (25 ℃, 2% aqueous solution, Brookfield viscometer).

In a preferred embodiment, the binder composition may include a binder and an additive made of a cellulose component in a mixed weight ratio of 1 to 2: 6 to 8 as a ratio of a binder: additive made of a cellulose component.

In still another aspect, the present invention relates to a diesel particle filter having a honeycomb structure, comprising the binder composition for the diesel particle filter and a support component. As the support component, a component known as a known diesel particle filter support may be used without limitation, and preferably, it may be cordierite having a low thermal expansion coefficient. The cordierite may be a mixed powder containing a material selected from the group consisting of MgO, Al (OH) ₃ , Al ₂ O ₃ , SiO ₂ , talc, kaolin and silica in a predetermined ratio. It can be prepared from a cordierite starting raw material comprising in the ratio of. In one specific embodiment, the filter support is based on 100 parts by weight of cordierite, 20 to 35 parts by weight of walnut shell, 1 to 5 parts by weight of graphite, 7 to 10 parts by weight of the binder composition according to the present invention And it may include 1 to 2 parts by weight of polyvinyl alcohol.

The diesel particle filter may include mixing components (eg, cordierite starting materials, binder compositions, walnut cells, graphite, polyvinyl alcohol, etc.) included in the filter; Molding the mixture prepared in the mixing step into a honeycomb structure; Heating the molded body formed in the molding step; And it may be prepared through the step of firing the molded product heated in the heating step. Each step of the manufacturing method may be applied as it is applied in the manufacturing method of a known ceramic honeycomb diesel particle filter.

Since the binder composition for a diesel particle filter according to the present invention as described above has a low content of sodium chloride of less than 0.3% by weight, it has a low coefficient of thermal expansion, and the diesel particle filter manufactured using the same has high mechanical properties.

Hereinafter, the configuration of the present invention will be described in more detail with reference to specific examples. However, it will be apparent to those skilled in the art that the scope of the present invention is not limited by the description of the embodiments.

EXAMPLE

<Examples 1-5 and Comparative Examples 1-5>

As shown in Table 1 below, the walnut shell is 100 parts by weight of raw material consisting of 18.56% by weight of kaolin, 10.83% by weight of calcined kaolin, 40.28% by weight of talc, 15.35% by weight of aluminum oxide, 7.38% by weight of aluminum hydroxide and 7.6% by weight of silica. 15 parts by weight was added, 5 parts by weight of each of 10 organic binders having different sodium chloride contents, 1 part by weight of an inorganic binder, and 1 part by weight of triethylin glycol (TEG) were mixed, followed by kneading using a Sigma mixer. It was. The sodium chloride content of the 10 kinds of the binder (the binder including the cellulose component) is different as shown in Table 2, respectively.

Subsequently, extrusion was carried out using an extrusion die of 200 cpsi, dried using a high frequency dryer, and then processed to 50 × 160 mm.

Subsequently, the workpiece was calcined at a temperature of 1410 for 6 hours to prepare the diesel particle filters of Examples 1 to 5. As can be seen in Table 1 and Table 2, the sodium chloride content of the binders of Examples 1 to 5 is according to the present invention, but the sodium chloride content of the binders of Comparative Examples 1 to 5 is outside the scope of the present invention.

Comparative example
One Comparative example
2 Comparative example
3 Comparative example
4 Comparative example
5 Example
One Example
2 Example
3 Example
4 Example
5 china clay
(Polyplate-P01) 18.56 18.56 18.56 18.56 18.56 18.56 18.56 18.56 18.56 18.56 Calcined kaolin
(GXL) 10.83 10.83 10.83 10.83 10.83 10.83 10.83 10.83 10.83 10.83 talc
(Hon-50) 40.28 40.28 40.28 40.28 40.28 40.28 40.28 40.28 40.28 40.28 Aluminum oxide
(A152SG) 15.35 15.35 15.35 15.35 15.35 15.35 15.35 15.35 15.35 15.35 Aluminum hydroxide
(H-42M) 7.38 7.38 7.38 7.38 7.38 7.38 7.38 7.38 7.38 7.38 burr
(KS-1000) 7.60 7.60 7.60 7.60 7.60 7.60 7.60 7.60 7.60 7.60 Raw material system 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 Walnutshell 0.00 5.00 10.00 15.00 20.00 25.00 30.00 35.00 40.00 45.00 bookbinder
(A) 5.00 bookbinder
(B) 5.00 bookbinder
(C) 5.00 bookbinder
(D) 5.00 bookbinder
(E) 5.00 bookbinder
(F) 5.00 bookbinder
(G) 5.00 bookbinder
(H) 5.00 bookbinder
(I) 5.00 bookbinder
(J) 5.00 Actigel 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 TEG 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 WAX 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00

A B C D E F G H I J Binder viscosity 3,070 12,800 11,840 15,400 15,920 3,790 11,840 12,560 13,840 15,240 Sodium chloride content 1.33 0.33 0.26 0.22 0.22 0.22 0.17 0.17 0.11 0.14

<Test Example 1>

The thermal expansion coefficients of the diesel particle filters prepared through Examples 1 to 5 and Comparative Examples 1 to 5 were measured and shown in Table 3 below. The coefficient of thermal expansion was measured using a coefficient of thermal expansion (Dilatometer).

Comparative example
One Comparative example
2 Comparative example
3 Comparative example
4 Comparative example
5 Example
One Example
2 Example
3 Example
4 Example
5 Coefficient of thermal expansion
(25 ~ 800, * 10 ^-6 /) 1.15 1.06 0.90 1.03 1.08 1.03 0.73 0.56 0.48 0.55

As shown in Table 3 above, when the content of sodium chloride in the binder is less than 0.3% by weight, it was confirmed that the diesel particle filter produced had a significantly low coefficient of thermal expansion. Therefore, the binder composition for the diesel particle filter according to the present invention is reduced in the content of the unique sodium chloride impurities, showing an excellent effect of providing a diesel particle filter having a honeycomb structure excellent in thermal properties.

Claims (10)

A binder and an additive composed of a cellulose-based component,
The binder composition for the diesel particle filter, characterized in that it comprises less than 0.3% by weight sodium chloride relative to the total composition weight as impurities of the cellulose component. The binder composition for a diesel particle filter according to claim 1, wherein the sodium chloride is included in less than 0.2% by weight. The binder composition of claim 1, wherein the composition has a viscosity of 4,000 to 15,000 cps. The binder composition of claim 1, wherein the additive is at least one selected from the group consisting of triethylene glycol and wax. The binder composition for a diesel particle filter according to claim 1, wherein the binder and the additive made of the cellulose component are included in a mixed weight ratio of the binder made of the cellulose component: 1 to 2: 6 to 8 as an additive. The diesel particle filter containing the binder composition for diesel particle filters of any one of Claims 1-5. The diesel particulate filter of claim 6, wherein the diesel particulate filter has a honeycomb structure. The diesel particulate filter of claim 6, further comprising cordierite, graphite and walnut cells. The binder composition according to claim 8, wherein 20 to 35 parts by weight of walnut shell, 1 to 5 parts by weight of graphite, and the binder composition of any one of claims 1 to 4 are used based on 100 parts by weight of cordierite. Part by weight and 1 to 2 parts by weight of polyvinyl alcohol, diesel particle filter. (a) mixing the binder composition for a diesel particle filter of any one of claims 1 to 4, cordierite starting material, graphite and polyvinyl alcohol;
(b) molding the mixture prepared in step (a) into a honeycomb structure;
(c) heating the molded body molded in the step (b); And
(d) firing the molded product heated in the step (c), the method of manufacturing a diesel particle filter.

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