JPH03269080A - Sealed pillar and sealing of cavity in pillar - Google Patents

Abstract

PURPOSE:To obtain the subject pillar having light weight, free from whistling noise and useful for automobile, etc., by mixing a foaming agent to a molten hot-melt composition, physically foaming the composition and sealing the inner cavity of a pillar with the foamed product. CONSTITUTION:A molten hot-melt composition [e.g. a mixture of a thermoplastic rubber (e.g. styrene/butadiene block copolymer) and a tackifier (e.g. rosin)] is mixed with a foaming agent (e.g. air or n-pentane) and physically expanded. The objective pillar is produced by sealing the inner cavity of a pillar with the foamed product.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a shield pillar and a method for sealing a void within the pillar. The present invention relates to a pillar in which a sealing material is loaded into the internal void in order to prevent this, and a method for sealing the void within the pillar.

[Prior art and problems to be solved by the invention] Pillars such as front pillars and center pillars that constitute part of the chassis of automobiles are usually U-shaped with a hinge part in order to reduce the weight of the car body. It is made up of a cylindrical body made by joining two panel steel plates at the hinge parts,
Although the openings at both ends are temporarily closed with other metal members, the structure is insufficient in terms of airtightness.

In pillars with such a cylindrical structure, when the car is running, especially when the car is running at high speeds where high-speed airflow is generated along the outer periphery of the car body, a portion of the high-speed airflow flows through the void inside the pillar while producing a whistling noise. This sometimes interfered with the quietness inside the car.

For this reason, conventionally, the following methods (1) to (3) for sealing the internal pillar voids have been proposed, and some of them have been put into practical use.

(1) A method in which slow-recovery slab urethane foam is manually compressed and successively inserted into the opening provided in the side wall of the pillar until the void inside the pillar is filled to seal it. (See Publication No. 139739).

(2) A method of filling the void inside the pillar with a thermosetting sealant made by covering a compressed foam that has approximately the same size as the shape of the void to be filled when restored with a thermosetting foam material ( (See Japanese Unexamined Patent Publication No. 1-164641).

(3) A method of filling a void in a pillar with a thermosetting foam sealing material in which an object having a shape that roughly matches the void to be filled is coated with a thermosetting foam (Japanese Patent Application Laid-Open No. 1-166
(See Publication No. 939).

However, the sealing methods shown in (1) to (3) above all require the molded material to be manually filled into the void inside the pillar, which is complicated and has serious problems in that it is not compatible with automation. there were.

For this reason, it has been desired to develop a method for sealing the void within a pillar that is simple and suitable for automation.

The present invention has been made in view of the above circumstances, and its purpose is to provide a method for sealing a void within a pillar that is simple and suitable for automation, and a shield pillar manufactured by applying the sealing method. There is something to do.

[Means for Solving the Problems] The shield pillar according to the present invention for achieving the above object is made of a foam obtained by mixing a blowing agent such as gas with a molten true melt composition and physically foaming the mixture. The key point is that the void within the pillar is sealed, and the method for sealing the void within the pillar according to the present invention involves mixing the true melt composition in a molten state with a foaming agent and physically foaming it. The main idea is to inject it into the internal cavity and then cool and solidify it.

The hot melt composition used as a sealing material in the present invention must not only be foamable but also capable of being cooled and solidified in a foamed state.

Such foamable hot melt compositions generally include a thermoplastic rubber, a tackifier, and a diluent as essential ingredients.

Examples of the thermoplastic rubber include styrene/isoprene block copolymer (SIS), styrene/butadiene block copolymer (SBS), styrene/ethylene/butylene block copolymer (SEBS), polypropylene, and polyethylene. . Note that the term "thermoplastic rubber" in this specification also includes thermoplastic resins as described above.

The true melt composition in the present invention may contain one type of these or two or more types thereof.

The above-mentioned tackifiers include rosin-based natural resins,
There are rosin ester type, terpene type, terpene phenol type, hydrogenated terpene type, etc. Petroleum resins include copolymer resins of C5 type and C9 type, and hydrogenated resins of these.

By using an appropriate amount of this tackifier, it becomes possible to improve adhesion and desorption from the steel plate, and to reduce the melt viscosity.

The above diluent is used to adjust the viscosity of the hot melt composition to an appropriate level so that it can be physically foamed by mixing gases such as air, carbon dioxide gas, nitrogen gas, or low boiling point liquids such as n-pentane. belongs to.

Such viscosity-adjusting diluents include, for example, paraffin wax and oil.

In addition, the hot melt composition of the present invention may further contain an antiaging agent such as an amine type or phenol type, or a filler such as silica, talc, mica, clay, calcium carbonate, etc.

The weight ratio of each component of the hot melt composition in the present invention varies depending on the type 11 of each component, but usually 15 to 50 parts by weight of thermoplastic rubber (hereinafter referred to as "r part") and 30 to 60 parts of tackifier. , a composition containing about IO to 40 parts of diluent is suitable from the viewpoint of foamability and adhesiveness. Furthermore, when using a material containing an anti-aging agent or a filler, it is preferable to use one containing less than 2 parts and 10 parts, respectively, for the same reason.

A hot melt foam as a sealing material in the present invention can be obtained by mechanically stirring and mixing a gas such as air or a low boiling point liquid into the hot melt composition as described above to form a foam.

In the present invention, the reason why the spreadable true melt composition is used in the form of a foam is to reduce the weight of the pillar.

The hot melt composition used must have a foaming life that is practical. If the foaming life is short and the foaming life is degassed before cooling and solidifying after application, it must be lightweight. Unable to achieve
This is because it cannot be put to practical use. Furthermore, compared to the case of using a foamable true melt composition in which a so-called chemical foaming agent that decomposes on heating and generates gas is added to thermoplastic rubber, foaming is performed by mixing gas from the outside as in the present invention. Physical foaming is preferable for continuous operation without the risk of foaming during heating and melting.

[Function] In the shield pillar according to the present invention, even if airflow does not enter the pillar, the airflow is completely prevented from entering because the void within the pillar is sealed with the true melt foam. Therefore, no wind noise is generated.

〔Example〕

Hereinafter, the present invention will be explained in more detail based on examples, but the present invention is not limited to the following examples in any way, and can be practiced with appropriate modifications within the scope of the gist thereof. It is.

FIG. 1 and FIG. 2 are a cross-sectional view and a vertical cross-sectional view, respectively, of a shield pillar according to the present invention. Consists of a cylindrical body formed by joining panel steel plates 2.2 at hinge parts 2a, 2a, and a solid hot melt foam SF as a sealing material filled in the cylindrical body. . Openings 2 at both ends of shield pillar 1
b and 2b are each closed with an unillustrated steel material with an unavoidable gap.

In the shield pillar 1 configured as described above, even if high-speed airflow does not enter the shield pillar 1 through the opening 2b at one end, the void inside the pillar is sealed with the true melt foam SF, so the high-speed airflow will No flow can flow through the pillar, so the generation of wind noise is completely prevented.

Hereinafter, a method for sealing the internal void portion of the pillar when manufacturing the shield pillar 1 will be described.

FIG. 3 is a perspective view showing the implementation state of this sealing method. It should be noted that members denoted by the same reference numerals as in FIG. 1 or 2 are substantially the same members.

First, the true-melt composition and gas are supplied to the applicator 3, and if necessary, pressure is applied and the gas is mechanically stirred into the true-melt composition to be mixed and melted.

Next, with one end opening 2b of the pillar closed with a steel plate, the supply hose 3a of the applicator 3 is inserted into the pillar from the other end opening 2b, and the true melt composition and gas are removed from the supply hose 3a. A molten mixture is released. Then, at the same time as it is released, the gas in the molten mixture becomes countless small balls and forms the true melt foam M.
In this way, the molten mixture continues to be discharged until the formed hot melt foam MF is completely filled into the pillar internal cavity, and at the point when the molten mixture is filled, the molten mixture is discharged from the supply hose 3a. Stop emission.

Note that, in order to uniformly fill the pillar internal void, it is preferable to gradually retreat the supply hose 3a as the filling progresses.

Thereafter, the shield pillar 1 is obtained by cooling and solidifying the true melt foam MF by leaving it for a certain period of time to form a solid hot melt foam SF.

Although the shield pillar 1 in which the internal cavity of the pillar is completely filled with the hot melt foam MF has been described above, the shield pillar according to the present invention is not limited to such a configuration, and the shield pillar 1 is not limited to such a configuration, For example, as shown in FIG. 4, a part of the pillar may be sealed as long as it has a structure that can prevent the flow of water.

Further, in the above embodiment, the case where the hot melt foam MF is filled from the opening at one end of the pillar is explained.
A separate injection port may be provided in the panel steel plate 2, and the true melt foam MF may be injected and filled from there during the repair process.

〔Effect of the invention〕

As explained in detail above, the shield pillar according to the present invention is lightweight and does not generate wind noise, and the method for sealing the internal cavity of the pillar according to the present invention uses a molten mixture consisting of a true melt composition and a gas. The present invention has excellent and unique effects, such as being able to completely seal the void within the pillar simply by adjusting the injection amount.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of a shield pillar according to the present invention, Figure 2 is a cross-sectional view of a shield pillar according to the present invention;
3 is a perspective view showing a state in which a method for sealing a cavity in a pillar is carried out, and FIG. 4 is a longitudinal sectional view of a partially sealed pillar according to the present invention. 1... Shield pillar, 2.2-passal steel plate, 2a,
2a-hinge, 2b, 2b-opening, 3-applicator, 3a--supply hose, MF--hot melt foam in molten state, SF--solid hot melt foam

Claims (1)

[Scope of Claims] 1. A shield pillar characterized in that a void within the pillar is sealed with a foam formed by physically foaming a hot melt composition in a molten state by mixing a foaming agent with the same. 2. Mixing a foaming agent into the hot melt composition in a molten state and injecting it into the void inside the pillar while causing physical foaming;
A method for sealing a void within a pillar, which comprises then cooling and solidifying.