JPH04336241A - Rigid structure for vehicle - Google Patents

Abstract

PURPOSE:To impart high rigidity, strength and heat insulating properties to a panel over a wide temp. range so as to follow the uneven surface of the panel in the structure bonded to the vibration substrate such as the floor panel of a vehicle. CONSTITUTION:A semi-gelled sheet formed from a composition consisting of a liquid epoxy resin, a coreactive curing agent, a foaming agent and a rubber elastomer or a thermoplastic resin is placed on a panel uneven steel plate shown by Fig 1 along with an elastic and rigid upper layer resin sheet and the whole is integrally welded in a heat drying process of panel painting and foamed.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a method for manufacturing floor panels, dash panels, wheel houses, ceiling panels, etc. for vehicles, etc., and more specifically, the present invention relates to a method for manufacturing floor panels, dash panels, wheel houses, ceiling panels, etc. for vehicles, etc. This invention relates to a panel structure that completely follows the panel by heating and in which each constituent layer is integrated.

0002

BACKGROUND OF THE INVENTION It is desired to improve the quality of large substrate surfaces such as floor panels, dash panels, wheel houses, ceiling panels, etc. of vehicles by increasing their rigidity from the viewpoints of vibration control and improved solidity. This will be explained in more detail. It is desired that automobiles be made lighter from the viewpoint of environmental protection such as carbon dioxide emission regulations and resource conservation. In this regard, countermeasures have been taken such as reducing the thickness of the material and reducing the number of structural members. This decrease in strength leads to a lack of surface tension and rigidity, leading to problems such as a lack of solidity as a member. In order to solve this problem,
The publication proposes a method using a reinforcing material for the door panel. However, this method not only does not provide sufficient rigidity, but also requires a lot of manual installation work, making it extremely difficult to install.

Under these circumstances, the present inventors added a liquid epoxy resin and a heat-activated curing agent to a composition consisting of a vinyl chloride resin for paste, a plasticizer, a foaming agent, etc., and applied it as a plastisol. After that, we proposed a method of pasting this as a semi-gelling sheet to the required area, placing a rigid resin sheet on top of it, heating it, and foaming it (patent application No. 2003).
-75494), resulting in an excellent rigid structure. According to this invention, it has become possible to obtain a vehicle panel that is easy to attach, has high rigidity, and has a solid feel.

0004

[Problems to be Solved by the Invention] However, since this method contains vinyl chloride resin in the composition, thermal decomposition of the resin occurs at high temperatures, such as in the electrodeposition coating process in an automobile production line. There was a problem that there was a risk. Under these circumstances, the present invention can provide a vehicle structure that is lightweight and has high rigidity, and has a composition that has good heat resistance and can withstand, for example, an electrodeposition coating process. The object is to provide a rigid structure for a vehicle.

[0005]

[Means for Solving the Problems] According to the present invention, an upper layer sheet (2) made of an elastic and rigid synthetic resin sheet, and a lower layer sheet of foamed thermosetting resin sandwiched between the upper layer sheet and a vehicle panel. In the two-layer structure composed of (1), the lower layer sheet includes (A) 100 parts by weight of an epoxy resin having one or more epoxy groups in one molecule, and (B) 0 parts by weight of a co-reactive curing agent for epoxy resin. .5 to 20 parts by weight, (C)
Foaming agent with cracked gas temperature of 100-220℃ 0.5-20
parts by weight, (D) 0.05 to 5 parts by weight of surfactant, and (
E) is insoluble in the epoxy resin at room temperature and has a composition of 80 to 15
At least one selected from rubber elastic bodies that can be mixed and dispersed with the epoxy resin at a temperature of 0°C, or powdered thermoplastic resins that are insoluble in the epoxy resin at room temperature, do not contain halogen, and have an average particle size of 150 μm or less. 10-200 seeds
It is a sheet that contains part by weight and is semi-gelled by heating at a temperature below the decomposition gas generation temperature of the blowing agent (C), and the adhesive surfaces of these sheets and panels are fused together by heating. In addition, a rigid structure for a vehicle characterized by foaming is provided.

Another object of the present invention is to provide a vehicle structure in which the rigidity can be improved without increasing the weight of the vehicle by integrating the structure with various panels of the vehicle. Furthermore, for this type of vehicle structure, it is necessary to adhere to uneven panels by heat treatment during the drying process such as painting, and to complete the reaction, foaming, and fusion of each layer, and even at relatively high temperatures. Materials with less deterioration in physical properties are required as desirable properties, and the structure according to the present invention satisfies these requirements.

[0007] Each constituent layer related to the present invention will be explained below. The lower layer sheet (1) used in the present invention has a function as a spacer, and desirable properties as a spacer in a vehicle panel are lightweight, high rigidity, little change in physical properties due to temperature changes, and paint drying properties. It adheres and is fixed to the uneven panel during the process, and
This process has a high-magnification foaming effect. In the spacer composition of the present invention, the liquid epoxy resin used as component (A) contains one or more epoxy groups in the molecule, and examples of such resins include (i) bisphenol A, bisphenol Glycidyl ether based on F or resorcinol, ■
Polyglycidyl ether of phenol novolac resin or cresol novolac resin, ■Glycidyl ether of hydrogenated bisphenol A, ■Glycidylamine type, ■
Examples include linear aliphatic epoxide type, glycidyl ether of phthalic acid, hexahydrophthalic acid, or tetrahydrophthalic acid, and preferable epoxy equivalents are those having an epoxy equivalent of 100 to 300. These liquid epoxy resins may be used alone or in combination of two or more, and in order to impart toughness to the resulting foam, phenolic epoxy resins with ethylene oxide or propylene oxide addition may be used. Flexible epoxy resins such as resin, dimer acid type epoxy resin, and epoxy-modified NBR may be combined.

In the spacer composition of the present invention, a co-reactive curing agent for epoxy resin is used as component (B). The curing agent preferably has an exothermic peak temperature in the range of 100 to 200°C in combination with the epoxy resin, and examples of such curing agents include dicyandiamide, 4,4,'-diaminodiphenylsulfone, 2-n - imidazole derivatives such as heptadecylimidazole, isophthalic acid dihydrazide, N,N-dialkylthiourea derivatives, acid anhydrides such as tetrahydrophthalic anhydride, isophoronediamine, m-phenylenediamine, N-aminoethylpiperazine, fluoride Examples include boric acid complex compounds and trisdimethylaminomethylphenol. These curing agents may be used alone or in combination of two or more, and the amount added is from 0.5 to 100 parts by weight of the epoxy resin as the component (A). The range is 20 parts by weight. If this amount is less than 0.5 parts by weight, curing will be insufficient and the rigidity of the foam will be insufficient; if it exceeds 20 parts by weight, the rigidity of the foam will not improve in proportion to the amount, which is economically disadvantageous. becomes. The curing temperature here refers to the temperature of the medium at which the heat generated by curing reaches its peak when the mixture of epoxy resin and curing agent at room temperature is heated in an oil bath, heater, etc. In addition, preferred combinations and amounts of epoxy resin and curing agent depending on heating conditions can be easily determined by testing in advance. In the present invention, in addition to the curing agent of component (B), if necessary, curing accelerators such as alcohol, phenol, mercaptan, dimethylurea, aliphatic, imidazole, monuron, chlorotoluene, etc. etc. can be used.

In the spacer composition of the present invention, component (C) has a decomposition gas generation temperature of 100 to 220°C.
A high-temperature decomposition type blowing agent of °C is used. As such a high temperature decomposition type foaming agent, an organic foaming agent, an inorganic foaming agent, a high temperature expansion type capsule, etc. can be used. If the decomposition gas generation temperature is below 100°C, foaming may begin during the processing of semi-gel sheets, which will be described later, or gas may escape due to insufficient melting of the resin during foaming in the heating furnace, and the foaming ratio may not be large. Or it is difficult to obtain a homogeneous foam. Furthermore, if the temperature exceeds 220° C., the processing temperature of the composition becomes high and the resin deteriorates, making it difficult to obtain a foam of good quality. Examples of such organic blowing agents include azodicarbonamide, p-toluenesulfonyl hydrazide, dinitrosopentamethylenetetramine, 4,4'-
Examples include oxybisbenzenesulfonyl hydrazide. The decomposition temperature of these organic blowing agents can be easily adjusted by adding urea, zinc compounds, lead compounds, etc. Examples of inorganic blowing agents include sodium hydrogen carbonate and potassium borohydride, and examples of high-temperature expansion microcapsules include those obtained by encapsulating low-boiling hydrocarbons with vinylidene chloride resin.

[0010] In the present invention, any of the above-mentioned organic blowing agents, inorganic blowing agents, and high-temperature expansion type microcapsules can be used, but organic blowing agents are suitable from the viewpoint of expansion ratio and economical efficiency. . Further, these blowing agents may be used alone or in combination of two or more. The amount added is selected within the range of 0.5 to 15 parts by weight per 100 parts by weight of the liquid epoxy resin (A). If this amount is less than 0.5 parts by weight, foaming will be insufficient, and if it exceeds 15 parts by weight, the expansion ratio will not improve in proportion to the amount, and problems such as roughened foam cells will often occur. In order to obtain a dense foam having a uniform cell diameter and a rigid cell membrane, it is advantageous for the particles of the blowing agent to have a small particle size, for example, 0.1 to 0.6 mm, preferably 0.1 to 0.6 mm. 0
．． In order to obtain a foam having a cell diameter of around 3 mm, the particle diameter is preferably 20 μm or less, preferably 10 μm or less, and uniform. In the present invention, a foaming accelerator can be used in addition to the foaming agent, if necessary. This foaming accelerator includes calcium stearate,
Examples include barium stearate, sodium and potassium compounds, and urea.

In the spacer composition of the present invention, a surfactant is used as component (D). This surfactant has the role of improving the cell structure. Examples of the surfactant include alkyl sulfate salts such as sodium lauryl sulfate and sodium myristyl sulfate, alkylaryl sulfonates such as sodium dodecylbenzenesulfonate and potassium dodecylbenzenesulfonate, sodium dioctylsulfosuccinate, Preferred examples include sulfosuccinic acid ester salts such as sodium dihexyl sulfosuccinate, fatty acid salts such as ammonium laurate and potassium stearate, anionic surfactants such as polyoxyethylene aryl sulfate ester salts and rosinate salts. In addition, sorbitan esters such as sorbitan monooleate and polyoxyethylene sorbitan monostearate, nonionic surfactants such as polyoxyethylene ethers, polyoxyethylene alkylphenyl ethers, and polyoxyethylene alkyl esters, cetylpyridinium chloride, Cationic surfactants such as cetyltrimethylammonium bromide can also be used. These surfactants may be used alone or in combination of two or more. The amount added is selected within the range of 0.05 to 5 parts by weight, preferably 0.2 to 3 parts by weight, per 100 parts by weight of the liquid epoxy resin (A). If it is less than 0.05 parts by weight, it cannot play the role of improving the cell structure, and even if it is more than 3 parts by weight,
However, the stability of the cell is not improved, and in some cases, it may cause discoloration due to decomposition during heating. As for the method of adding the surfactant, when the rubber elastic body or thermoplastic resin used as component (E) is in powder form, it is advantageous to spray it in advance and dry and adsorb it uniformly before use.

The spacer composition (E) of the present invention contains a rubber elastic material or a halogen that is insoluble in the epoxy resin (A) at room temperature and can be mixed and dispersed with the epoxy resin at a temperature of 80 to 150°C. No thermoplastic resin can be used. In this case, the rubber elastic body can be used not only in solid form but also in viscous liquid form, while the thermoplastic resin composition must be in powder form with an average particle size of 150 μm or less. When this rubber elastic body or thermoplastic resin is heated to 150°C or higher,
It is desirable to use a material that melts to form a homogeneous affinity with the epoxy resin of component (A) and maintains the melt viscosity of the composition stably, such as chloroprene rubber, butadiene-acrylonitrile rubber, Rubber elastic bodies such as carboxyl-modified butadiene-acrylonitrile rubber, epoxy-modified butadiene-acrylonitrile rubber, butadiene rubber, isoprene rubber, ethylene-vinyl acetate copolymer, polyphenylene ether, ethylene-vinyl alcohol copolymer, acrylonitrile-styrene copolymer , polyamide, polyvinyl butyral, polyvinyl acetal, polymethyl methacrylate, acrylonitrile-butadiene-styrene copolymer, methyl methacrylate-butadiene-styrene copolymer, polystyrene, and the like. These may be used alone or in combination of two or more. The component (E) has the function of adjusting the melt viscosity of the composition, and also has the function of improving the toughness of the obtained foam. The amount of component (E) added is selected within the range of 10 to 200 parts by weight per 100 parts by weight of the liquid epoxy resin of component (A). It depends on the type of rubber elastic body or halogen-free thermoplastic resin added, but if it is less than 10 parts by weight, there is no function to adjust the melt viscosity or to improve the toughness of the foam, and on the other hand, if it is more than 200 parts by weight, Although this also depends on the type of rubber elastic body or thermoplastic resin, disadvantages arise in that the expansion ratio of the foam does not improve or the rigidity of the foam decreases.

In the composition of the present invention, it is important to balance the affinity between the epoxy resin as the component (A) and the rubber elastic material and thermoplastic resin as the component (E). It is necessary to appropriately select the particle size, amount added, etc. In particular, in terms of affinity balance, a system in which polymers are completely compatible with each other during melting is not desirable;
It is desirable to be in a stable dispersed mixture state. Therefore, depending on the combination of polymers, it is desirable to add a plasticizer to increase the mutual affinity and thereby adjust the affinity of the polymer tube. This plasticizer also has the function of adjusting melt viscosity, and examples of the plasticizer include phthalate esters such as dioctyl phthalate and dibutyl phthalate, phosphate esters such as tricresyl phosphate, dioctyl adipate, etc. Further, conventionally known fatty acid esters such as adipic acid condensates of ethylene glycol, trimellitic acid esters, glycolic acid esters, chlorinated paraffins, and alkylbenzenes can be used.

[0014] In the composition of the present invention, an epoxy resin diluent may be added as necessary for the purpose of facilitating initial mixing, increasing the amount of fillers, etc. added. Examples of the diluent include reactive diluents such as butyl glycidyl ether, allyl glycidyl ether, phenyl glycidyl ether, cresyl glycidyl ether, persatic acid glycidyl ether, dibutyl phthalate, dioctyl phthalate, butyl benzyl phthalate, tricresyl phosphatate, etc. Mention may be made of non-reactive diluents such as phate, acetyltributyl citrate, aromatic process oil, pine oil, 2,2,4-trimethyl-1,3-pentadiol isobutyrate. A thixotropic agent or a filler may be added to the composition of the present invention, as necessary, for the purpose of adjusting coating properties such as processability and viscosity, or increasing the amount to reduce costs. etc. may be added. Examples of the thixotropic agents include silicic acid-based agents such as anhydrous silicic acid and hydrous silicic acid, bentonite-based agents such as organic bentonite, asbestos-based agents such as Cylodex, and organic agents such as dibenzylidene sorbitol. In addition, examples of fillers include calcium carbonate, mica, talc, kaolin clay, celite, asbestos, perlite, baryta,
Silica, silica sand, flaky graphite, dolomite limestone, gypsum,
Examples include aluminum powder.

The spacer composition of the present invention contains the essential components (A), (B), (C), (D) and (E) and various additive components used as desired. It can be adjusted using a quantitative method, for example, a planetary mixer, kneader, roll, Henschel mixer, etc. The spacer composition of the present invention prepared in this manner has a melt viscosity of 2.5 x 103 to 5 x 104 dP at the decomposition gas generation temperature of the blowing agent contained therein.
a. It is preferably in the range of s. If the melt viscosity is outside the above range, it will be difficult to obtain a foam with a good appearance, an expansion ratio of 5 times or more, and an average cell diameter of 0.5 mm or less. Further, in the structure of the present invention, this spacer composition is used in the form of a semi-gelled sheet. That is, the prepared composition is preformed into a sheet at a temperature below the decomposition temperature of the blowing agent,
After that, the upper layer sheet (2) made of a restraining material is laminated, and then in the next heating step, for example, a painting drying step,
It foams at 0°C to 200°C and is cured by crosslinking of the epoxy resin. The expansion ratio of such a lower sheet is 2 to 30 times, preferably 5 to 10 times. A foam with a foaming ratio of 2 times or less can of course function as a spacer, but this is not the purpose of the present invention from the viewpoint of light weight, and if the foaming ratio is 30 times or more, the strength of the foam cells will be insufficient and the vehicle will be damaged. There may be problems with durability depending on where it is used. Further, the thickness of the lower layer sheet after foaming is 1 to 50 mm, preferably 3 to 30 mm. If it is less than 1 mm, it will not function effectively as a spacer, and if it is more than 50 mm, it will become impractical in vehicle applications, which is the purpose of the present invention, because the interior space of the vehicle will become narrow and heating processes such as drying processes will be difficult. In this case, homogeneous foaming properties cannot be obtained.

[0016] The upper layer sheet (2) applied to the present invention is:
It has high elastic modulus, excellent durability, and is lightweight, and for this type of vehicle, it is necessary to consider the applicability to vehicle applications and required quality, such as the ability to follow uneven panels due to heating during the paint drying process. There is. Desirable materials that meet these conditions include thermoplastic resin sheets containing tackifier resins such as rosin resins, terpene resins, aliphatic petroleum resins, alkylphenol-acetylene resins, xylene resins, and coumaron indene resins. Thermosetting plastic sheets using rubber as a base polymer, such as butadiene rubber, styrene-butadiene rubber, etc., are suitable. The thickness of the upper layer sheet is not particularly specified, but from the same viewpoint as the lower layer, it is usually used with a thickness of about 0.5 to 3 mm as a sheet formed on a vehicle panel, etc. be done. The production of such a structure according to the present invention includes a lower layer sheet,
Each layer of the upper layer sheet may be individually placed on a vehicle panel, and the panel lower layer sheet and the upper layer sheet may be fused together and foamed together by heating during a paint drying process, etc., and at the same time, may be made to follow the irregularities of the vibration board. However, two layers of sheets may be laminated in advance and fused to the panel in a heating process such as a coating drying process, and the sheets may be foamed and conform to the irregularities of the panel.

[0017]

[Effects of the Invention] The rigid structure for a vehicle according to the present invention is placed on a panel such as a ceiling panel or a door panel of a vehicle, and the lower sheet is foamed by heating, and each layer and between panels are firmly fixed and a vibration substrate is formed. It can also be made to follow the uneven shape of. The structure obtained in this way has a structure with a dense cell structure with a high expansion ratio in the lower layer and has a rigid, heat-resistant spacer function, so it not only exhibits high rigidity over a wide temperature range but also This provides solidity to the vehicle body panels and creates a structure with excellent insulation properties.

[0018]

[Examples] The present invention will be explained below with reference to Examples and Comparative Examples. The materials and test methods used for the test are as follows. I. Test materials ■ Vibration board: 0.8 mm thick steel plate ■ Lower layer sheet (spacer sheet) After creating a spacer composition by mixing it in a Hobart mixer for 20 minutes at the compounding ratio shown in Table 1 below, it was printed on release paper to a specified thickness. It was applied with This was heated at 120° C. for 100 seconds to create a semi-gelled sheet.

[0019]

[Table 1]

(2) Upper layer sheet Thermoplastic compositions having the compounding ratios shown in Table 2 were melted and mixed in an autoclave heated to 200°C, and the resulting mixture was adjusted to a predetermined thickness using a hot press. (Material code - F)

[
0021

[Table 2]

[0022] A thermosetting composition having the compounding ratio shown in Table 3 was kneaded with a roll and formed into a sheet with a predetermined thickness.

[0023]

[Table 3]

II. Test method Lower layer sheet and upper layer sheet each 15 x 300 mm,
A structure was created by combining a steel plate with a thickness of 0.8 mm, and the rigidity ratio of each structure was measured at 20, 40, and 60°C. Lamination and foaming of each layer is done after placing each layer on a steel plate.
Heat treatment was performed in an oven under the conditions of 30 minutes at °C. The stiffness ratio was calculated from the moving frequency of the resonance point of the mechanical impedance using Equation 1 below, and the stiffness ratio at 200 Hz was determined by interpolation. In addition, the measurement frequency is 1 to 1000Hz
It is.

[0025]

[Math. 1] Rigidity ratio = (f0/f)2・{m1+m2)/m
1}

[0026] Here, f0 is the resonant frequency when the lower sheet and the upper sheet are bonded to the steel plate, f is the resonant frequency when the steel is alone, m1 is the areal density of the steel plate alone, m
2 is the areal density of the lower sheet and the upper sheet. In addition, the followability to the uneven shape was determined by cutting out the material of the lower layer sheet and the upper layer sheet mentioned above to a width of 20 mm and a length of 250 mm, respectively, and corrugating the uneven shape shown in FIG. 1 (A) front view and (B) side view. A heating test was conducted in an oven on a steel plate with a height of 7.8 mm perpendicular to the wave shape, and the followability was observed. The heating conditions are the same as in the case of bonding. The evaluation was as follows: "○" indicates that the products are in close contact with each other without any gaps, "△" indicates that some gaps remain but are acceptable for use, and "x" indicates that the gaps remain and pose a problem in use. In addition, the uniformity of foam cells can be determined by observing their appearance.
The foaming ratio was classified into four levels: ○, △, and ×, and the foaming ratio was measured. Table 4 shows the results of the followability and foaming properties of the examples, and Table 5 shows the results of the comparative examples. As shown in Table 4, the rigid structures according to the present invention in Examples 1 to 6 had good foamability, rigidity, and unevenness followability, whereas in the comparative examples shown in Table 5, The structures of Examples 1 and 2 are significantly inferior in foamability, and the structures of Comparative Example 3 and structures are significantly inferior in rigidity.

[0027]

[Table 4]

[0028]

[Table 5]

[Brief explanation of the drawing]

FIG. 1 is a front view and a side view of a steel plate used in a followability test.

Claims (1)

[Claims] Claim 1: A two-layer structure consisting of an upper layer sheet (2) made of an elastic and rigid synthetic resin sheet and a lower layer sheet (1) of foamed thermosetting resin sandwiched between the upper layer sheet and the vehicle panel. In, the lower layer sheet is (A)1
Epoxy resin 1 having one or more epoxy groups in the molecule
00 parts by weight, (B) co-reactive curing agent for epoxy resin 0.
5 to 20 parts by weight, (C) cracked gas temperature 100 to 220
℃ foaming agent 0.5 to 20 parts by weight, (D) surfactant 0.
05 to 5 parts by weight, and (E) a rubber elastic material that is insoluble in the epoxy resin at room temperature and can be mixed and dispersed with the epoxy resin at a temperature of 80 to 150°C, or a halogen-free material that is insoluble in the epoxy resin at room temperature. Not contained, average particle size 150
Contains 10 to 200 parts by weight of at least one kind selected from powdered thermoplastic resins having a size of 10 μm or less, and is semi-gelled by heating at a temperature below the decomposition gas generation temperature of the blowing agent (C). 1. A rigid structure for a vehicle, which is a sheet, and the adhesive surfaces of the sheet and panel are integrally fused and foamed by heating.