JPH06278145A - Filling up method for car body frame member with foam - Google Patents

Abstract

(57) [Summary] [Structure] The method for filling a foam in a vehicle body frame member according to the present invention is to fill the foam in the entire cross-sectional space of the vehicle body frame member formed by the outer panel and the inner panel made of steel plates. Of the steel sheets used for the outer panel and the inner panel, at least one of the steel sheets has a foamable sheet made of a thermoplastic resin composition containing a thermoplastic resin, a foaming agent and a cross-linking agent fixed to one surface thereof, and a steel sheet. Form the cross-sectional space part with the outer panel and the inner panel with the foamable sheet fixed to the inside, and heat the foamable sheet in the drying line in the rustproofing process of the vehicle body to cover the whole cross-sectional space part. It is characterized by being filled with foam. According to the above foam filling method, it is possible to fill the foam into the entire cross-sectional space portion of the vehicle body frame member formed of the outer panel and the inner panel made of steel plates more easily than before. it can.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for filling foam in a vehicle body skeletal member, and more particularly, to foaming the entire cross-sectional space formed by an outer panel and an inner panel made of steel plates such as automobile pillars. The present invention relates to a technique of filling a body to eliminate a cross-sectional space portion, shut off a sound generated from an engine, and prevent transmission of a wind noise generated by a flow of air during traveling.

[0002]

BACKGROUND OF THE INVENTION Body frame members such as automobile pillars, roofs, roof side rails, rockers, and wheel houses have a cross-sectional space portion formed by an outer panel and an inner panel made of steel plates. Since the sound generated from the engine cannot be shut off and the wind noise generated by the flow of air during traveling cannot be prevented from being transmitted, the vehicle body frame member as described above is
It is required to be a soundproof material.

[0003] Therefore, conventionally, a method has been proposed in which foam is filled in the entire cross-sectional space of a vehicle body skeletal member such as an automobile pillar, roof, roof side rail, rocker, and wheel house to improve quietness in the automobile. Has been done.

For example, a hole is made in a steel plate such as a pillar having a cross-sectional space portion already assembled with a steel plate, a liquid foamable urethane is injected through the hole, and then heat foaming is performed to form the whole cross-sectional space portion with the foamed urethane. There is a method of filling.

However, in this method, in order to inject the liquid foamable urethane, it is necessary to provide an injection hole in the steel sheet, and manual injection work is required, and further, the liquid foamable urethane leaks. There is a problem that the process is complicated because it needs to be specially sealed so as not to exist.

Further, Japanese Patent Laid-Open No. 62-29477 discloses a bag in which a liquid foam material such as a polyurethane stock solution is injected through a hole formed in a steel plate such as a pillar having a sectional space already assembled with the steel plate. It is described that an excellent vibration damping effect and sound insulating effect can be obtained by inserting the body, heating and foaming the foam material, and filling the cross-sectional space portion with the foam.

Further, in Japanese Patent Laid-Open No. 61-116509, a foamed polyurethane containing, for example, a foaming agent is discharged into the cavity in the body of an automobile and cured to fill the cavity with foam. A method, a method utilizing the so-called floss method, is described.

In the methods described in these publications, it is necessary to provide an insertion hole for the bag body and an injection hole for the foamed polyurethane, and both of them are carried out after the vehicle is assembled. There is a problem that is complicated.

Japanese Unexamined Patent Publication (Kokai) No. 64-12976 discloses a soundproof structure for an automobile pillar portion in which a foamed body foamed in the automobile pillar portion is closely packed over almost the entire area. Specifically, there is described a method in which a heat-foamable sheet (in an unfoamed state) is inserted into a pillar in a wound state and heated to fill almost all the inside of the pillar portion with a foam. There is.

The method described in this publication has a problem that it is necessary to provide an insertion hole for the wound foaming sheet, and since the work is carried out after the vehicle is assembled, the work is complicated and the work is complicated. .

Further, there have been proposed many methods of providing a vibration-damping porous soundproof layer by foaming a foamable sheet inside an automobile wheel house or the like. However, since the conventional foamable sheet has a low expansion ratio of about 5 times, it is necessary to make the sheet thickness extremely thick, and as a result, there is a problem that the cost becomes high.

Therefore, the foam can be filled in the entire cross-sectional space of the vehicle body frame member formed of the outer panel and the inner panel made of steel plates more easily than before, and the cost can be reduced. The advent of filling methods has long been desired.

[0013]

It is an object of the present invention to solve the problems associated with the prior art as described above, and to provide an overall cross-sectional space portion of a vehicle body frame member formed of an outer panel and an inner panel made of steel plates. It is another object of the present invention to provide a method capable of filling a foam more easily than before.

[0014]

SUMMARY OF THE INVENTION A method of filling foam in a vehicle body skeletal member according to the present invention is an outer panel for filling a foam into the entire cross-sectional space of a vehicle body skeletal member formed of an outer panel and an inner panel made of steel plates. And, among the steel sheets used for the inner panel, a foamable sheet made of a thermoplastic resin composition containing a thermoplastic resin, a foaming agent and a cross-linking agent is fixed to one surface of at least one of the steel sheets and fixed to the steel sheet. With the foamable sheet inside, a cross-sectional space portion is formed by the outer panel and the inner panel, and the foamable sheet is heated in the drying line in the rustproofing process of the vehicle body to form the cross-sectional space portion with foam. It is characterized by filling.

The thermoplastic resin preferably used in the present invention has a vinyl acetate content of 1 polymerized by a high pressure method.
~ 35 wt%, melt flow rate 1-50 g / 10
Of ethylene / vinyl acetate copolymer (EVA), or this ethylene / vinyl acetate copolymer (EVA) or high-pressure low density polyethylene (LDPE) has 0 or more functional groups of unsaturated carboxylic acid or acid anhydride thereof. 0.001-
It is a resin containing 10% by weight.

[0016]

DETAILED DESCRIPTION OF THE INVENTION A method for filling a foam body in a vehicle body frame member according to the present invention will be specifically described below.

The method for filling a foam in a vehicle body skeletal member according to the present invention is such that when the foam is filled in the entire cross-sectional space of the vehicle body skeletal member formed of the outer panel and the inner panel made of steel sheets, the outer panel and the inner panel are used. Among the steel plates used for the panel, on one surface of at least one of the steel plates, a foamable sheet made of a thermoplastic resin composition containing a thermoplastic resin, a foaming agent and a cross-linking agent is fixed, and the foam fixed to the steel plate. Section is formed by the outer panel and the inner panel with the elastic sheet inside, and the foamable sheet is heated in the drying line in the rustproofing process of the vehicle body to fill the entire section space with foam. .

First, the thermoplastic resin composition used in the present invention will be described. Thermoplastic resin composition The thermoplastic resin composition forming the expandable sheet used in the present invention has a resin composition that exhibits adhesiveness with a steel sheet, and also has excellent foamability, and at least thermoplastic It contains a resin, a foaming agent and a crosslinking agent. Also,
A filler may be contained in the thermoplastic resin composition.

As the above-mentioned thermoplastic resin, specifically,
The following copolymers and resins are preferably used. (1) Polymerized by a high pressure method, having a vinyl acetate content of 1 to 35% by weight and a melt flow rate (ASTM D-1
505) is an ethylene / vinyl acetate copolymer (EVA) having a content of 1 to 50 g / 10 min. (2) The ethylene / vinyl acetate copolymer (EVA) has a functional group, for example, a functional group of an unsaturated carboxylic acid or an acid derivative thereof in an amount of 0.001 to 10% by weight, preferably 0.1.
A resin containing 05 to 5% by weight (hereinafter, sometimes referred to as a graft-modified ethylene / vinyl acetate copolymer). (3) High-pressure method low-density polyethylene (LDPE) has a functional group, for example, a functional group of unsaturated carboxylic acid or its acid derivative in an amount of 0.001 to 10% by weight, preferably 0.05.
Resin containing 5 to 5% by weight (hereinafter sometimes referred to as graft-modified low-density polyethylene).

The method for producing the ethylene / vinyl acetate copolymer of the above (1) is not particularly limited as long as it is a production method in which polymerization is carried out by a high pressure method, and a conventionally known production method can be adopted. it can.

The above-mentioned graft-modified ethylene-vinyl acetate copolymer (2) is partially or wholly graft-modified. As the unsaturated carboxylic acid or acid derivative thereof used in the graft modification, specifically,
Acrylic acid, maleic acid, fumaric acid, tetrahydrophthalic acid, itaconic acid, citraconic acid, crotonic acid, isocrotonic acid, nadic acid ^TM (endocis-bicyclo [2,
2,1] -hept-5-ene-2,3-dicarboxylic acid) or an unsaturated carboxylic acid or a derivative thereof, such as an acid halide, amide, anhydride or ester is used. Malenyl, maleimide, maleic anhydride, citraconic anhydride, monomethyl maleate, dimethyl maleate, glycidyl maleate and the like are used. Among these, unsaturated carboxylic acids or acid anhydrides thereof are preferable, and maleic acid, nadic acid ^TM or acid anhydrides thereof are particularly preferably used.

In order to produce a modified product by graft-copolymerizing the above-mentioned ethylene / vinyl acetate copolymer with a graft monomer selected from such unsaturated carboxylic acid or its acid derivative, various conventionally known methods are available. Can be adopted. For example, there is a method of melting an ethylene / vinyl acetate copolymer and adding a graft monomer to perform graft copolymerization, or a method of dissolving the ethylene / vinyl acetate copolymer in a solvent and adding a graft monomer to perform graft copolymerization. is there. In any case, in order to efficiently graft-copolymerize the above-mentioned graft monomer, it is preferable to react in the presence of a radical initiator such as an organic peroxide.

In the present invention, the content of the functional group obtained by mixing the graft-modified ethylene / vinyl acetate copolymer having a high content of functional groups and the non-grafted ethylene / vinyl acetate copolymer is the above-mentioned. The copolymer may be within the range, or the functional group content obtained by graft-modifying the ethylene / vinyl acetate copolymer may be within the above range.

The above graft-modified low density polyethylene (LDPE) (3) is usually synthesized by radical polymerization of ethylene or ethylene and a small amount of vinyl monomer at 1,000 to 2,000 at 200 to 300 ° C. To be done.

The above graft-modified low-density polyethylene is
Some or all of them are graft-modified. The unsaturated carboxylic acid or its acid derivative used in the graft modification is the same as in the case of the graft modified ethylene / vinyl acetate copolymer in (2) above.

In order to produce a modified product by graft-copolymerizing the above-mentioned unsaturated carboxylic acid or a graft monomer selected from its acid derivative with the above-mentioned high-pressure low-density polyethylene (LDPE), a modified product can be produced. The method can be adopted. For example, there is a method of melting high-pressure low-density polyethylene and adding a graft monomer for graft copolymerization, or a method of dissolving high-pressure low-density polyethylene in a solvent and adding a graft monomer for graft copolymerization. In any case, in order to efficiently graft-copolymerize the above-mentioned graft monomer,
It is preferable to react in the presence of a radical initiator such as an organic peroxide.

In the present invention, a polyethylene having a functional group content in the above range, which is obtained by mixing a graft-modified low-density polyethylene having a high content of functional groups and a high-pressure method low-density polyethylene that has not been graft-modified, is used. Alternatively, it may be a polyethylene having a functional group content obtained by graft-modifying a high-pressure low-density polyethylene in the above range.

As the above-mentioned foaming agent, since the thermoplastic resin composition is required to foam in the drying furnace in the anticorrosion treatment step, it should have a decomposition temperature at which foaming occurs at 150 to 180 ° C. for 10 to 30 minutes. is necessary. Therefore, a foaming agent having a decomposition temperature commensurate with the foaming temperature may be selected. Further, in the present invention, even a foaming agent having such a decomposition temperature or higher can be used. For example, when using azodicarbonamide, it is necessary to change the decomposition temperature of azodicarbonamide to 200 ° C. within the above range, but by using a foaming aid such as metallic zinc, for example, zinc stearate, the decomposition of azodicarbonamide can be performed. The temperature can be adjusted within the above foaming temperature range.

Specific examples of the foaming agent used in the thermoplastic resin composition include azodicarbonamide, barium azodicarboxylate, N, N'-dinitrosopentamethylenetetramine and 4,4-oxybis (benzenesulfonyl). Hydrazide), diphenylsulfone-3,3-disulfonylhydrazide, p-toluenesulfonyl semicarbazide, trihydrazinotriazine, biurea, zinc carbonate and the like. Among these, a large amount of gas is generated, the gas generation end temperature is sufficiently lower than the deterioration start temperature of the ethylene / vinyl acetate copolymer, the graft-modified ethylene / vinyl acetate copolymer, and the graft-modified low-density polyethylene, Azodicarbonamide (combined with metallic zinc), N, N'-dinitrosopentamethylenetetramine and trihydrazinotriazine are particularly preferable.

In the present invention, the foaming agent is 5 to 20 parts by weight based on 100 parts by weight of the thermoplastic resin composition.
It is preferably used in a proportion of 10 to 15 parts by weight. The foam obtained from the foamable sheet of the thermoplastic resin composition containing the foaming agent in the above proportion has a foaming ratio of 10 to 40.
Double. In the present invention, the preferred expansion ratio is 15
~ 25 times.

In the present invention, the thermoplastic resin composition may contain a filler in an amount of 0 to 50 parts by weight based on 100 parts by weight of the total amount of the thermoplastic resin and the filler.

The filler is effective in reducing the shrinkage rate and increasing the rigidity, and examples of the filler include an inorganic filler and an organic filler. In the present invention, an inorganic filler is preferably used, and specifically, talc, calcium carbonate (d = 2.7 g / cc), barium sulfate (d = 4.2).
g / cc), glass fiber and the like are preferably used.

In order to improve the heat resistance of the foam, a heat stabilizer may be added to the above-mentioned thermoplastic resin composition within the range not impairing the object of the present invention. When imparting flame retardancy to the foam, a flame retardant may be added to the thermoplastic resin composition as long as the object of the present invention is not impaired.

The cross-linking agent used in the above-mentioned thermoplastic resin composition must be such that the cross-linking reaction does not occur during sheeting for molding the thermoplastic resin composition into a foamable sheet and the cross-linking reaction does not occur under the above-mentioned foaming conditions. I won't. For that purpose, the decomposition temperature of the crosslinking agent needs to be in the range of 120 to 170 ° C. An organic peroxide is effective as such a cross-linking agent, and the degree of cross-linking can be adjusted by the addition amount thereof. Further, in order to increase the expansion ratio of the foam obtained from the expandable sheet of the thermoplastic resin composition, it is necessary to increase the degree of crosslinking and increase the amount of organic peroxide added.

In the present invention, the organic peroxide is used in a ratio of 0.1 to 2.0 parts by weight based on 100 parts by weight of the total amount of the thermoplastic resin and the filler. As the organic peroxide used in the present invention, specifically, 3,
3,5-trimethylhexanoyl peroxide (1), octanoyl peroxide (2), decanoyl peroxide (3), lauroyl peroxide (4), succinic acid peroxide (5), acetyl peroxide (6), t-butylperoxy ( 2-ethylhexanoate) (7), meta
-Toluoyl peroxide (8), benzoyl peroxide (9), t-butyl peroxyisobutyrate (1
0), 1,1-bis (t-butylperoxy) -3,5,5-trimethylcyclohexane (11), 1,1-bis (t-butylperoxy) cyclohexane (12), t-butylperoxymaleic acid ( 13), t-butyl peroxylaurylate (1
4), t-butylperoxy-3,5,5-trimethylcyclohexanoate (15), cyclohexanone peroxide (16), t-butylperoxyisopropyl carbonate (17), 2,5-dimethyl-2,5-di (Benzoylperoxy) hexane (18), t-butylperoxyacetate (19), 2,2-bis (t-butylperoxy) butane (2
0), t-butylperoxybenzoate (21), n-butyl-4,4-bis (t-butylperoxy) valerate (2
2), di-t-butylperoxyisophthalate (23),
Methyl ethyl ketone peroxide (24), α, α'-bis (t-butylperoxyisopropyl) benzene (25),
Dicumyl peroxide (26), 2,5-dimethyl-2,5-di (t-butylperoxy) hexane (27), t-butylcumyl peroxide (28), diisopropylbenzene hydroperoxide (29), di-t -Butyl peroxide (3
0), para-menthane hydroperoxide (31), 2,5-
Dimethyl-2,5-di (t-butylperoxy) hexyne-3
(32), 1,1,3,3-tetramethylbutyl hydroperoxide (33), 2,5-dimethylhexane-2,5-dihydroperoxide (34), cumene hydroperoxide (35), t-butyl hydroperoxide (36), 1,1-di- (t-butylperoxy) -3,3,5-trimethylcyclohexane (37),
Examples thereof include 1,1-di-t-butylperoxycyclohexane (38) and didecanoyl peroxide (39). Among them, t-butylperoxymaleic acid (13), t-butylperoxylaurylate (14), 2,5-dimethyl-2,5-di (benzoylperoxy) hexane (18), 1,1-di- (t
-Butylperoxy) -3,3,5-trimethylcyclohexane (37), 1,1-di-t-butylperoxycyclohexane (38), didecanoyl peroxide (39) are preferred.

Foamable Sheet The foamable sheet used in the present invention is prepared as follows. That is, additives such as the above-mentioned thermoplastic resin, foaming agent, cross-linking agent, filler, heat stabilizer and flame retardant are mixed in a Henschel mixer or the like in the above proportions, and a Banbury mixer, an extruder. And the like are melted and plasticized at a temperature at which the foaming agent and the cross-linking agent are not decomposed by a kneading machine such as the above to prepare pellets uniformly mixed and dispersed. Then, an unfoamed foamable sheet is prepared from the pellets by using an extruder or a calender molding machine. The thickness of the foamable sheet used in the present invention varies depending on the site where the vehicle body is used, but is usually in the range of 0.5 to 10 mm.

Method for Filling a Foam Body In the method for filling a foam body in a vehicle body frame member according to the present invention, the foam body is filled in the entire cross sectional space of the vehicle body frame member formed of an outer panel and an inner panel made of steel plates. At this time, first, of the steel plates used for the outer panel and the inner panel, a foamable sheet made of a thermoplastic resin composition containing a thermoplastic resin, a foaming agent and a crosslinking agent is fixed to one surface of at least one steel plate. .

The foamable sheet fixed to the above steel plate is
The thickness, width, and length dimensions are determined according to the site of use of the vehicle body, and the foamable sheet prepared as described above is cut into a predetermined dimension and prepared.

The foamable sheet cut to a predetermined size is fixed to one surface of at least one of the steel plates used for the outer panel and the inner panel. Whether the above-mentioned foamable sheet is fixed to both the steel plate used for the outer panel and the steel plate used for the inner panel, or whether the above-mentioned foamable sheet is fixed to either one, depends on the thickness and the expansion ratio of the foamable sheet. It depends on whether or not the entire cross-sectional space portion can be filled with the foam when the foamable sheet is foamed.

There are various fixing methods for the foamable sheet, but it is necessary to fix the steel sheets for the outer panel and the inner panel before welding and assembling. As a method of fixing the foamable sheet, specifically, (1) a method of temporarily fixing the foamable sheet to the steel plate with an adhesive material, (2) heat the foamable sheet to the steel plate using a heat-adhesive film or the like. Examples of the method include bonding, or (3) a method in which the steel sheet is provided with a claw fold, a fixing protrusion such as bolting, a hole is formed in the foamable sheet, and then the foamable sheet is fixed to the steel sheet. Of these, the method (1) is particularly preferable because it is simple.

Next, the outer panel and the inner panel form a cross-sectional space portion with the foamable sheet fixed to the steel plate as described above inside. The above steel plates are welded,
A vehicle body is formed that is composed of a vehicle body frame member having a sectional space portion.

Next, the foamable sheet is heated in a drying line in the rustproofing process of the vehicle body to fill the entire cross-sectional space with foam. The vehicle body formed as described above,
In the rustproofing process, after being immersed in the rustproofing agent, it is heat-treated in a drying furnace. When the vehicle body passes through the drying oven, the foamable sheet fixed to the steel plate foams and expands to fill the entire cross-section space with foam. The foam formed as described above is chemically bonded and adhered to the steel sheet by the adhesive resin contained in the thermoplastic resin composition forming the foam sheet. The gel fraction of the foam formed as described above is 10 to 70% by weight, preferably 30 to 50% by weight.

[0043]

EFFECTS OF THE INVENTION According to the present invention, it is not necessary to provide an injection hole for a foamable resin composition or an insertion hole for a foamable sheet in a steel sheet as in the conventional case, and the outer panel and the inner panel made of a steel sheet are used. The entire cross-sectional space of the body frame member to be filled can be filled with foam more easily than before.

Further, since the foamable sheet used in the present invention has a foaming ratio of 10 times or more, which is higher than that of the conventional foamable sheet, the cost can be reduced. Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited to these examples.

[0045]

Example 1 First, the following compounds were prepared as components of a thermoplastic resin composition. 1) Ethylene / vinyl acetate copolymer (hereinafter abbreviated as EVA) [Mitsui-DuPont Polychemical Co., Ltd., Evaflex ^™ EV550; vinyl acetate (VA) content = 14% (saponification method), MFR = 15 g / 10 minutes (ASTM D-150
5)] 2) Foaming agent: Azodicarbonamide (hereinafter abbreviated as ADCA) 3) Foaming aid: Zinc stearate 4) Crosslinking agent: 1,1-di-t-butylperoxycyclohexane 5) Heat stabilizer: Iruganox 1010 (Ciba Geigy) EVA 100 parts by weight, ADCA 15 parts by weight,
After uniformly mixing 1.0 part by weight of zinc stearate, 1.0 part by weight of 1,1-di-t-butylperoxycyclohexane and 0.1 part by weight of a heat stabilizer with a Henschel mixer, a Banbury mixer Was melt-kneaded at 120 ° C. to obtain a pellet-shaped thermoplastic resin composition. The obtained pellets were in a non-foamed state.

Next, the pellets were subjected to sheeting at 140 ° C. by using a T-die with an extruder having a diameter of 65 mm to obtain a foamable sheet having a thickness of 5 mm and a width of 200 mm.
Then, the obtained foamable sheet is 50 mm in width and 20 in length.
Cut to a size of 0 mm, 10 mm at the top center of the sheet
I made a hole in the diameter. Further, two steel plates were pressed into a pillar shape. If these two steel plates are clamped on both sides, a pillar model 1 as shown in FIG. 1 is obtained.

Then, as shown in FIG. 2, a U-shaped notch having a length of 10 mm and a width of 8 mm was formed in one of the pressed steel plates 2a, and the steel plate 3 at the notch was folded back inward. After that, as shown in FIG. 3, the steel plate 3 in the cutout portion was inserted into the hole 5 of the foamable sheet 4 and further bent to fix the foamable sheet 4 to the steel plate 2a.

Next, the steel plate 2 to which the foamable sheet 4 is fixed
A and a steel plate 2b on which the foamable sheet 4 is not fixed are combined to form a pillar shape. The maximum distance between the steel plates 2a and 2b at this time was 50 mm.

Then, the pillar-shaped steel plate 2a,
2b was put in an oven at 170 ° C. for 30 minutes to heat the foamable sheet 4 fixed to the steel plate 2a. By the above heating,
The expandable sheet 4 fixed to the inner surface of the steel plate 2a foams and expands three-dimensionally, and as shown in FIG. 4, the foam 6 reaching the steel plate 2b facing the steel plate 2a is formed. That is, when the foam 6 and the steel plates 2a and 2b were cut in cross section, the space between the steel plates 2a and 2b was completely filled with the foam 6.

The foam 6 formed as described above is
The specific gravity was 0.04, the expansion ratio was 23 times, and the gel fraction was 38%. This gel fraction was determined as follows. That is, 0.3 g of the sample (foam) was placed in a # 100 mesh screen basket, and this sample was extracted with xylene for 3 hours using a Soxhlet extractor to obtain the extraction residual rate. Was taken as the gel fraction.

When the foam 6 and the steel plate 2b were peeled off, the foam material was broken and the foam was firmly bonded to the steel plate. It was confirmed that the foam 6 did not leak to the outer surface of the steel plate 2a from the hole formed in the cutout portion of the steel plate 2a.

Further, the surface rigidity of the pillars filled with the foam obtained as described above and the surface rigidity of the pillars of the hollow without the foam were determined by the following compression bending test. [Compression Bending Test] (1) Test Measuring Machine ・ ・ ・ Instron Universal Testing Machine 11
22 type (2) Measurement sample: Sample 8 having a shape as shown in FIG. 6 (3) Measurement method After mounting the lower surface of the sample 8 on the smooth pedestal 9 of the measuring machine, it is attached to the load cell 10. Tip diameter 1/2 inch ¢
The central portion of the sample 8 was compressed at a constant speed by the column 11 of No. 1 and the load and the amount of compressive strain were measured. (4) Test conditions Compression speed 20 mm / min Temperature 23 ° C. Fig. 8 shows the relationship between the load and the compressive strain amount obtained as described above for the pillar filled with the foam and the pillar having no foam. It is shown in the graph. Further, when the compression elastic gradient, which is an index of the surface rigidity, is obtained from this graph, the pillar having a hollow without foam has a compression elastic gradient of 1 or less.
1.0 kg / cm, and the pillars filled with the foam obtained as described above have a compression elastic gradient of 53.0 kg.
Was / cm. As described above, the surface rigidity of the pillars filled with the foam obtained as described above was significantly higher than the surface rigidity of the hollow pillars without the foam.

[0053]

[Examples 2 to 4] In Example 1, 15 m
The foamable sheet 4 was foamed in the same manner as in Example 1 except that a steel plate having holes of m, 10 mm, and 5 mm diameter was used as the steel plate 2b facing the steel plate 2a to which the foamable sheet 4 was fixed. The foam did not leak to the outer surface of the steel plate 2b from any of the holes.

[0054]

[Embodiment 5] As shown in FIG. 5, after a heat-resistant adhesive sheet 7 is partially adhered to one side of the foamable sheet 4 of Example 1, the foamable sheet 4 is attached to the steel sheet through the adhesive sheet 7. The expandable sheet 4 was heated and foamed under the same conditions as in Example 1 except that the sheet was bonded and fixed (not shown).

The foam formed as described above reaches the steel plate facing the steel plate to which the foamable sheet is fixed, and the space between the two steel plates is completely filled with the foam (Fig. (Not shown). Moreover, when the foam and the steel plate were peeled off,
The steel sheet and the foam were not adhered to each other at the portion where the pressure-sensitive adhesive sheet was adhered, but the part where the pressure-sensitive adhesive sheet was not adhered showed material destruction of the foam, and the foam was strongly adhered to the steel sheet.

[0056]

Example 6 A steel plate was placed on a hot press set at 160 ° C. and heated, and a steel plate adhesive film having a thickness of 40 μm was formed thereon [graft-modified product of high-pressure process low-density polyethylene with an acid anhydride, containing functional groups]. Amount = 0.2% by weight, density = 0.92 g / cm ³ , MFR = 1.0 g / 10 min (A
STM D-1238)] was put on and melted.

Next, the foamable sheet of Example 1 was placed on the molten adhesive film, press-pressed, and then cooled. The foamable sheet was firmly adhered to the steel plate.
Then, the steel plate to which the foamable sheet was fixed as described above and the steel plate to which the foamable sheet was not fixed were assembled in a pillar shape and heat-foamed in the same manner as in Example 1.

The foam formed as described above reaches the steel plate opposite to the steel plate to which the foamable sheet is fixed, and the space between the two steel plates is completely filled with the foam. Further, when the foam and the steel plate were peeled off, material destruction of the foam was shown, and the foam was firmly adhered to the steel plate.

[Brief description of drawings]

FIG. 1 is a perspective view showing a shape of a pillar according to a first embodiment of the present invention.

FIG. 2 is a perspective view showing a state in which a steel plate of a notch portion provided for fixing a foamable sheet is bent and stood up in Example 1 of the present invention.

FIG. 3 is a schematic perspective view showing a state in which the foamable sheet is fixed to a steel plate in Example 1 of the present invention.

FIG. 4 is a cross-sectional view of the pillar according to the first embodiment of the present invention, showing a state where the inside of the pillar is filled with a foam.

FIG. 5 is a schematic perspective view showing a state in which an adhesive sheet is partially attached to a foamable sheet in Example 5 of the present invention.

FIG. 6 is a perspective view showing the shape of a pillar sample used for a compression bending test in Example 1 of the present invention.

FIG. 7 is a schematic explanatory view of a compression bending test.

FIG. 8 is a graph showing a relationship between a load and a compressive strain amount of a pillar filled with a foam and a pillar having a hollow without a foam in Example 1.

[Explanation of symbols]

 1 …… Pillar model 2a, 2b ・ ・ ・ Steel plate 3 ・ ・ ・ ・ ・ Steel plate in the notch 4 ・ ・ ・ Expandable sheet 5 ・ ・ ・ Opened in the expandable sheet Hole 6 ・ ・ ・ Foam 7 ・ ・ ・ Adhesive sheet 8 ・ ・ ・ (Pillar) sample 9 ・ ・ ・ Measuring machine pedestal 10 ・ ・ ・ ・ ・ Load cell 11 ・ ・ ・・ Pole pillar

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Claims (5)

[Claims] 1. A steel plate used for the outer panel and the inner panel when at least one of the steel plates used for the outer panel and the inner panel is filled with a foam when filling the entire cross-sectional space of a vehicle body skeletal member. On one side, a foamable sheet made of a thermoplastic resin composition containing a thermoplastic resin, a foaming agent and a cross-linking agent is fixed, and the outer panel and the inner panel are made with the foamable sheet fixed to a steel plate inside. Forming a cross-sectional space portion, heating the foamable sheet in a drying line in a rustproofing process of the vehicle body, and filling the whole cross-sectional space portion with foam, filling the foam body in the vehicle body frame member. Method. 2. An ethylene / vinyl acetate copolymer (EVA) in which the thermoplastic resin is polymerized by a high pressure method and has a vinyl acetate content of 1 to 35% by weight and a melt flow rate of 1 to 50 g / 10 min. Or a resin in which the functional group of unsaturated carboxylic acid or its acid anhydride is contained in the ethylene / vinyl acetate copolymer (EVA) or high-pressure low density polyethylene (LDPE) in an amount of 0.001 to 10% by weight. The method for filling a foamed body in a vehicle body skeletal member according to claim 1, wherein: 3. The thermoplastic resin composition contains a filler in an amount of 0 to 50 parts by weight based on 100 parts by weight of the total amount of the thermoplastic resin and the filler. 2. The method for filling a foam in a vehicle body frame member according to 2. 4. The thermoplastic resin composition contains 5 to 20 parts by weight of a foaming agent with respect to 100 parts by weight of the thermoplastic resin composition. 7. A method for filling a foamed body in a vehicle body frame member according to. 5. The cross-linking agent is an organic peroxide,
The method for filling a foam in a vehicle body skeletal member according to claim 1, wherein the addition amount is 0.1 to 2.0 parts by weight with respect to 100 parts by weight of the thermoplastic resin composition.