CA2005735A1 - Multi-layer sheet structure for the reinforcement of panels, a method for the reinforcement of panels and a reinforced panel - Google Patents
Multi-layer sheet structure for the reinforcement of panels, a method for the reinforcement of panels and a reinforced panelInfo
- Publication number
- CA2005735A1 CA2005735A1 CA002005735A CA2005735A CA2005735A1 CA 2005735 A1 CA2005735 A1 CA 2005735A1 CA 002005735 A CA002005735 A CA 002005735A CA 2005735 A CA2005735 A CA 2005735A CA 2005735 A1 CA2005735 A1 CA 2005735A1
- Authority
- CA
- Canada
- Prior art keywords
- layer
- sheet structure
- plastic material
- structure according
- layer sheet
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B27/00—Layered products comprising a layer of synthetic resin
- B32B27/06—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
- C09J5/00—Adhesive processes in general; Adhesive processes not provided for elsewhere, e.g. relating to primers
- C09J5/06—Adhesive processes in general; Adhesive processes not provided for elsewhere, e.g. relating to primers involving heating of the applied adhesive
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B27/00—Layered products comprising a layer of synthetic resin
- B32B27/12—Layered products comprising a layer of synthetic resin next to a fibrous or filamentary layer
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Laminated Bodies (AREA)
Abstract
Abstract The invention relates to a multi-layer sheet structure for the reinforcement of panels. The multi-layer sheet structure comprises a supporting layer which in turn comprises a curable plastic material and a reinforcing material combined with or embedded in said curable plastic material. The multi-layer sheet structure further comprises an adhesive layer applied on said supporting layer on the side facing the panel to be rein-forced. The adhesive layer comprises a curable plastic material optionally provided with fillers or other additives. In order to achieve a reinforcing and stiffening effect as high as pos-sible without deformation of said panel, the adhesive layer, after curing, has a modulus of elasticity which is higher than the modulus of elasticity of the cured plastic material of the supporting layer, and the supporting layer, after curing, has a coefficient of thermal expansion which is essentially the same as the coefficient of thermal expansion of the panel to be re-inforced.
Description
2g~7~
A MULTI-LAYER SHEET STRUCTURE FOR THE REfNFORCEMENT OF PANELS, A METHOD FOR TIIE REINFORCEMENr OF PANELS
AND A REINFORCED PANEL
.
FIEL~ OF T~IE INVENTION
The present invention refers to a multi-layer sheet struc-ture for the reinforcement of panels, particularly of panels made of steel or aluminium sheet material or plastic material, said sheet structure including a supporting layer and an adhe-sive layer applied on said supporting layer on the side Eacing the panel to be reinforced. Further, the invention refers to a method for the reinforcement of panels, particularly of panels made of steel or aluminium sheet material or plastic material by using the multi-layer sheet structure of the invention.
Still further, the invention refers to a panel, preferably made of ste~l or aluminium sheet material or of plastic material, reinforced with the multi-layer sheet structure of the inven-tion.
BACKGROUND OF THE INVENTION
According to the status of the art, special multi-layer sheet structures or laminates are used for reinforcing, parti-cularly for stiffening sheet metal parts, molded plastic arti-5~73s cles, and the like, for example parts of car bodies. For exam-ple, such multi-layer sheet structures may be composed of a first supporting layer, that is to say the actual rein~orcing or stiffening layer, for example a glass cloth ~onded by a heat-curable plastic resin, the surface of which is provided with a second layer of heat-curable stic~y plastic resin. Such a composite may be used for reinforcing ~lat and disiled sheet metal by depositing a piece of the composi-te onto the sheet metal, the sticky surface facing the latter, an(l by thermally treating said composite. By this, on the one hand, bonding of the composi~e and, on the other hand, curing of the resin layers is effected, thereby creating a joint between the sheet metal and the fiber-reinforced layer which is stif~ against shearing. In this way, a considerable reinforcement and stiff-ening of the sheet metal section involved can be effected in a simple manner and without substantial additional weight.
In order to simplify the application of the reinforcing structure, the second resin layer in general is made to have a sticky surface so that the multi-layer sheet structure, once deposited on the sheet metal, is adhering there until thermally treated.
It is known from previous experience that, when locally reinforcing, for example, sheet metal of car bodies by means of such mu]ti-layer sheet structures, al-though invisibly applied to the back of the sheet metal part, more or less visible de-formations oE the sheet metal section involved are produced.
This is of course most unwelcome in the manufacturing oE auto~
mobiles, since either these deformations injure the aesthetic to an intolerable extent, or time and work consuming reworking of the visible sheet metal surface will be necessary.
The reason for said deformations are stresses which are created during c~ring of the multi-layer sheet structure which, in general, is composed of pLastic material. It is to be empha-sized that, on the one hand, a certain volume contraction takes place, and, on ths other hand, when heat-curable plastic mate-rials are cooled aEter thermal curing, the panel to be rein-forced and the multi-layer sheet struc~ure have different co-efficients of thermal expansion.
As disclosed in EP-Bl-0,053,361, these problems are said to be solved by means of an adhesive film composed of a first layer o~ an epoxy resin composition and a second layer of an epoxy resin composition laminated to said first layer, said layers having the following characteristic properties:
(a) The first layer, that is to say the actual reinforcing layer (or "supporting layer" in the terminology of the present invention) is to have a comparatively high modulus of elasticity of between 30 and 500 kg/mm2, after appli-cation on-to the me-tal plate and curing.
It is clearly disclosed in said reference, that this layer takes care of the very task of stiffening~
(b) The second layer, that is to say the adhesive layer for fixing -the actual reinforcing layer on the panel to be re-inforced, is to have a comparatively low modulus of elasti-2~ 735 city of between O.l and 22 kg/mm .
In said reference, it is emphasized expressis verbis thatthe modulus of elasticity oE this adhesive layer is to be so low that it is insufficient for stiffening the panel.
In this way, it is possible to avoid a visible deformation of the panel to be reinforced, for example of a sheet metal part of a car, such as a door, a deck lid~ et cetera. Moreover, the outer first layer, which has a comparatively high modulus of elasticity, brings about the actual reinforcing effect. The second layer facing the panel to be reinforced, that is to say the adhesive layer, has such a low modulus of elasticity that it cannot deform the panel -to be reinorced.
The main disadvantage of this arrangement is that the rein-forcing effect is rather poor because of -the comparatively low modulus of elasticity of the adhesive layer. A joint between the actual reinforcing layer and the panel to be reinforced, which is stiff against shearing) cannot be made in this way.
OBJECTS OE THE INVENTION
It is the object oE the present invention to provide a mul-ti-layer sheet structure for the reinforcement of panels made e.g. of sheet metal or plastic Inaterial which multi layer sheet structure, on the one hand, provides an improved reinEorcing and stiffening of said panel and, on the other hand, excludes any deformation of said panel after curing said multi-layer sheet structure.
S~MMARY OF THE INVENTION
The invention provides a multi-layer sheet structure for the reinforcement of panels. The sheet structure includes a supporting layer and an adhesive layer applied on said supporting layer on the side facing the panel to be reinforced.
The supporting layer comprises a curable plastic material and a reinforcing material combined with or embedded in said curable plastic material. The supporting layer is determined, before curing, to have, after curing, a coefficient of thermal expansion which is essentially the same as the coefficient of thermal expansion of the panel to be reinforced. The adhesive layer comprises a curable plastic material optionally provided with fillers or other additives, and said adhesive layer is determined, before curing, to have, after curing, a modulus of elasticity which is higher than the modulus of elasticity of th~
cured plastic material of said supporting layer.
The invention further provides a method for the reinforcement of panels by means of a multi-layer sheet structure. Thereby, in a first step, the coefficient of thermal expansion of the panel to be reinforced is determined~ In a second step, a supporting layer comprising a curable plastic material and a reinforcing material combined with or embedded in said curable plastic material is prepared, the ratio of the plastic material to the reinforcing material being chosen in a manner that the ~
2 ~ 3 ~
supporting layer, after curing, has a coefficient of thermal expansion ~hich is essentially the same as the coef~icient of thermal expansion of the panel to be rein~orced.
In a third step, an adhesive layer comprising a curable plastic material is applied onto said supporting layer, said adhesive layer, after curing of said plastic material, having a modulus of elasticity which is higher than the modulus of elas-ticity of the cured plastic material of said supporting layer.
In a four-th step, the multi-layer sheet structure obtained by the second and third steps is fixed onto said panel to be reinforced, with the side of said adhesive layer facing said panel to be reinforced. In a fif~h, final step, the fixed mul-ti-layer sheet structure is treated so as to cure the plastic materials of said supporting layer and said adhesive layer and to firmly bond said multi-layer sheet structure with said panel to be reinforced.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a sectional view of a multi-layer sheet structure of the invention in its unused state.
Fig. 2 to ~ are sectional views of three composites com-prising multi-layer sheet structures oE the invention and show-ing nega-tive, zero and positive deElection, respectively.
DETAILED DESCRIPTION OF THE INVENTION
The ~erm "modulus of elasticity" signifies, throughout the description and the claims, the modulus of elasticity deter-mined by the tensile test.
The tests made by the Inventors clearly show that deforma-tion of, for example, a sheet metal is in the first place caus-ed by the different coefficients of thermal expansion of the two materials - in the case of said example of the metal panel to be reinforced and the plastic material used for stiffening -when the arrangement is cooled after heat-curing. Obviously, volume contraction is of secondary importance, since it takes place above the glass transition region where forces can scar-cely be transmitted.
In this manner, a multi-layer sheet structure having, for example, two layers can be built up so that after its applica-tion onto the sheet metal $o be reinforced and its curing a composite of shee-t metal/adhesive layer/reinforcing layer is obtained which is symmetrical with respect to its thermal ex-pansion. It is a matter of course that the reinforcing layer is to have the same coefficient of thermal expansion as the slleet metal to be reinforced. Under these preconditions, the sheet metal on the one hand, and the reinforcing layer on the other hand will symmetrically contract during the cooling process so that no deformations of the sheet metal can occur. The contrac-tion of the adhesive layer, because of the symmetry present, is compensated in itself and does not have any detrimental effect to the shape or the appearance of -the sheet metal.
2 01~11S~7~
The coeEficient of thermal expansion of the supporting layer can be adjusted within a wide range to that of the panel to be rein~orced, due to the feature -that the adhesive layer, after curing the resin material contained in said supporting layer, has a higher modulus of elas-ticity than the cured resin material of said supporting layer, and due to the fact that the resin material used for said supporting layer can freely be combined with reinforcing materials. On the other hand, the colnbination "resin material o~ the supporting layer + reinforc-ing material" has a higher modulus of elasticity than the ad-hesive layer. By this, it is ensured, particularly if the dif-ferences with respect to the moduli of elasticity of said ad-hesive layer on the one hand and oE said supporting layer on the other hand are not too important, that a link is created between said supporting layer and said panel to be stiffened which is stiff against shearing. This also ensures a pronounced stiffening and reinforcing effect onto the panel.
The coefficient of thermal expansion can very easily be controlled by means of the volu.me ratio of resin material to reinforcing material.
Glass cloth is particularly sui-table as reinforcing mate-rial. It turned out that in the case of stiffening a steel sheet (which probably is the most frequent case in practice) a ratio of glass cloth to resin material of, roughly spoken, 50:50 by weight, and preEerably of about 48:52 by volume, is to be aimed at.
IJI practice, for stiffening a panel in accordance with the present invention, one proceeds as follows:
~ 3 ~
First, th~ coefficient of thermal expansion o~ the panel to be reinforced is determined.
Then, a supporting layer comprising a curable resin materi-al and a reinforcing material combined therewith or embedded therein is produced, selecting the ratio of resin material to reinforcing material in such a manner that said supporting lay-er, after curing, has essentially the same coefficient o~ ther-mal expansion as the panel to be reinforced.
Thereafter, an adhesive layer is deposited onto said sup-porting layer, said adhesive layer comprising a curable resin material and having, after curing of said resin material, a total modulus of elasticity which is higher than that of the cured resin material o~ the supporting layer.
The multi-layer sheet structure prepared as described above is fixed onto the panel to be reinforced, the adhesive layer facing the panel to be reinforced, and said multi-layer sheet structure is treated, for example heat-treated, in order to cure the resin materials of said supporting layer and of said adhesive layer and to firmly combine said multi-layer sheet structure with the panel to be reinforced.
DESCRIPTION O~ PREFERRED EMBODIMENTS
The mul-ti-layer sheet structure shown in sec~ion in Fig. 1 was manufactured as explained below. The multi-layer sheet structure, as it is present before its application, is general-ly marked by the reference numeral "1" and has the following ;
.
5~73~
general structure:
The supporting layer 2 is made of a glass cloth 3, for ex-ample of a glass-fiber roving cloth having a speciEic gravity o~ 620 g/m . Said glass cloth 3 is embedded in a resin layer 4 consisting of a heat-curable resin. The following materials are most suitable:
- Compound a) 90 parts liquid epoxy resin (for example "Epikote 828"
of Shell) 10 parts dicyandiamide - Compound b) 90 parts diluted epoxy resin (for example "Epikote 215"
of Shell) 10 parts dicyandiamide ~ ~
60 parts solid epoxy resin (Eor example "Epikote 1001"
of Shell) 5 parts dicyandiamide 35 parts dimethylketone (serving as a solvent for the impregnation and being afterwards evaporated) The modulus of elasticity of the cured resin is adjusted to a value of 2100 N/mm2 by suitable selection of the resin ma-terial and the fillers. The percentage of the glass in layer 2 was varied as explained hereafter. The thickness of layer 2 was jt73~
about 0.6 mm.
An adhesive layer 5, which essentially consisted of a heat-curable self-adhering resin, was applied to said layer 2. The following materials are most suitable:
- Compound a) 30 parts liquid epoxy resin (for example "Epikote 828"
of Shell) 20 parts solid epoxy resin (for example "Epikote 1001"
of Shell) 4 par~s dicyandiamide 20 parts talcum 26 parts fly ash ("Fillite") 35 parts liquid epoxy resin (for example "Epiko-te 828"
of Shell) 25 parts solid epoxy resin ~for example "Epikote 1001"
of Shell) 5 parts dicyandiamide 5 parts mica 30 parts talcum The modulus o~ elasticity o~ the cured resin was adjusted to a value of 3700 N/mm2 by suitable selection of the resin ma-terial and the fillers. This value was clearly higher than the modulus of elasticity of the resin used for layer 2. The thick-ness of layer 5 was about 0.6 mm.
~ ~ O ~ 3 5 On the other hand, the modulus of elasticity of the cured layer 2, that is to say of the combination of resin and glass cloth, varied depending on the percentage of glass, but was at least 5000 N/mm . Particularly, the coefficient of thermal expansion can by varied by varying the ratio by volume of resin to glass cloth.
The back side of layer 2 was covered by an aluminium sheet 6 having a thickness of 20 um, whereas the front side of layer 5, when the multi-layer sheet structure l was unused, was covered by a removable protecting paper 7.
COMPARATIVE TESTS
The following tests were made with this multi-layer sheet structure:
TEST l A flat strip of steel sheet 8 having a length of 400 mm, a width of 25 mm and a thickness of 0.75 mm was provided wi-th a multi-layer sheet structure 1 in the manner described above and shown in Fig. l. The total thickness of said multi-layer sheet structure l was l.6 mm. The percentage by volume of glass cloth 3 in the layer 2 of multi-layer sheet structure l was 51 %.
After application, the composite of steel sheet 8 and multi-layer sheet structure l was heat-treated at 180C for 30 min-utes. The resulting deflection dl of the composite towards Z ~ ~7 3~
the sheet metal was 1.8 mm (shown very exaggeratedly in Fig.
2). This is due to the fact that the coe~ficient of thermal expansion of the reinforcing layer 2 of ~he mul-ti-layer sheet structure 1 was lower than that of the steel sheet strip 8.
The same experimental setup as in Tes-t 1 was used with the difference that the percentage by volume of glass cloth 3 in layer 2 of the multi-layer sheet structure 1 was 48 %. As shown in Fig. 3, the composite of steel sheet 8 and multi-layer sheet structure 1 did not distort9 that is to say that any eventual deformation was below the accuracy of measurement of 0.1 mm.
The same experimental setup and the same conditions as in Test 1 were used with the difference that the percentage by volume of glass cloth 3 in layer 2 of the multi-layer sheet structure 1 was 44 %. The resulting deflection d2 of the com-posite of steel sheet 8 and multi-layer sheet structure 1 to-wards the multi-layer sheet structure was 2.6 mm (shown very exaggeratedly in Fig. 4). This is due to the fact that the co-efficient of thermal expansion of the reinforcing layer 2 of multi-layer sh0et structure 1 was higher than that of the steel sheet strip 8.
21D~:115~35 A sample of the multi-layer sheet structure of Test 2 having the dimensions of 80 x 80 mm was applied onto a steel sheet having the dimensions of 200 x 200 x 0.75 mm. No de1ection could be detected wi-th the naked eye after heat-treatment at 180C for 30 minutes.
A steel sheet strip without an applied multi-layer shee~
structure 1 having a length of 150 mm, a width of 25 mm and a thickness of 0.75 mm was symmetrically supported at a distance of 100 mm. Then, the force Fo, acting onto the center of the sample, which is necessary for deflecting said steel sheet strip by 10 mm, was determined. AEterwards, the test was re-peated by using a steel sheet strip of the same dimensions but provided with a multi-layer sheet structure according to Test 1. Th0 force necessary for deflecting said re.inforced steel sheet strip by 10 mm was Fv. The reinforcing factor, that is to say FV/Fo, was 9 4.
.
A steel sheet strip without a multi-layer sheet structure 1 applied onto it, having a length of 150 mm, a width of 25 mm ~ O O~j7 3 5 and a thickness of 0.75 mm was symmetrically supported at a distance of 100 mm. Then, the force Fo, acting onto the cen-ter oE the sample, which is necessary for deflecting said steel sheet strip by 10 mm was de-termined. Afterwards, -the test was repeated by using a steel sheet strip of the same dimensions but provided with a multi-layer sheet structllre according to Test 2. The force necessary for deflecting said reinforced steel sheet s-trip by 10 mm was Fv. The reinforcing factor, that is to say FV/Fo, was 9.1.
A steel sheet strip w;thou-t a multi-layer sheet structur~ 1 applied onto it, having a length of 150 mm, a width of 25 mm and a thickness of 0.75 mm was symmetrically supported at a distance of 100 mm. Then, the force Fo, acting onto the cen-ter of the sample, which is necessary for deflecting said steel sheet strip by lO mm was determined. Afterwards, the test was repeated by using a steel sheet strip of the same dimensions but provided with a multi-layer sheet structure according to Test 3. The force necessary for deflecting said reinforced steel sheet strip by 10 mm was Fv. The reinforcing factor, that is to say FV/Fo, was 9.l.
~5~735 CONCLUSIONS
The conclusions which can be drawn Erom these tests may be summarized as follows:
1. All tests (1 to 3 and 5 to 7) fundamentally showed a dis-tinctly better reinforcing effect onto the steel sheet sam-ple than reported by the prior art (for example in said EP-Bl-0,053,361).
2. No deformation of the steel sheet sample could be observed if the supporting layer and adhesive layer were designed in accordance with the present invention, as evidenced by Tests 2 and 6.
; 3. lf the supporting layer and adhesive layer were designed in accordance with the present invention, only an insignificant decrease of the reinforcing factor could be observed (9.1 against 9.4 in Tests 5 and 6).
A MULTI-LAYER SHEET STRUCTURE FOR THE REfNFORCEMENT OF PANELS, A METHOD FOR TIIE REINFORCEMENr OF PANELS
AND A REINFORCED PANEL
.
FIEL~ OF T~IE INVENTION
The present invention refers to a multi-layer sheet struc-ture for the reinforcement of panels, particularly of panels made of steel or aluminium sheet material or plastic material, said sheet structure including a supporting layer and an adhe-sive layer applied on said supporting layer on the side Eacing the panel to be reinforced. Further, the invention refers to a method for the reinforcement of panels, particularly of panels made of steel or aluminium sheet material or plastic material by using the multi-layer sheet structure of the invention.
Still further, the invention refers to a panel, preferably made of ste~l or aluminium sheet material or of plastic material, reinforced with the multi-layer sheet structure of the inven-tion.
BACKGROUND OF THE INVENTION
According to the status of the art, special multi-layer sheet structures or laminates are used for reinforcing, parti-cularly for stiffening sheet metal parts, molded plastic arti-5~73s cles, and the like, for example parts of car bodies. For exam-ple, such multi-layer sheet structures may be composed of a first supporting layer, that is to say the actual rein~orcing or stiffening layer, for example a glass cloth ~onded by a heat-curable plastic resin, the surface of which is provided with a second layer of heat-curable stic~y plastic resin. Such a composite may be used for reinforcing ~lat and disiled sheet metal by depositing a piece of the composi-te onto the sheet metal, the sticky surface facing the latter, an(l by thermally treating said composite. By this, on the one hand, bonding of the composi~e and, on the other hand, curing of the resin layers is effected, thereby creating a joint between the sheet metal and the fiber-reinforced layer which is stif~ against shearing. In this way, a considerable reinforcement and stiff-ening of the sheet metal section involved can be effected in a simple manner and without substantial additional weight.
In order to simplify the application of the reinforcing structure, the second resin layer in general is made to have a sticky surface so that the multi-layer sheet structure, once deposited on the sheet metal, is adhering there until thermally treated.
It is known from previous experience that, when locally reinforcing, for example, sheet metal of car bodies by means of such mu]ti-layer sheet structures, al-though invisibly applied to the back of the sheet metal part, more or less visible de-formations oE the sheet metal section involved are produced.
This is of course most unwelcome in the manufacturing oE auto~
mobiles, since either these deformations injure the aesthetic to an intolerable extent, or time and work consuming reworking of the visible sheet metal surface will be necessary.
The reason for said deformations are stresses which are created during c~ring of the multi-layer sheet structure which, in general, is composed of pLastic material. It is to be empha-sized that, on the one hand, a certain volume contraction takes place, and, on ths other hand, when heat-curable plastic mate-rials are cooled aEter thermal curing, the panel to be rein-forced and the multi-layer sheet struc~ure have different co-efficients of thermal expansion.
As disclosed in EP-Bl-0,053,361, these problems are said to be solved by means of an adhesive film composed of a first layer o~ an epoxy resin composition and a second layer of an epoxy resin composition laminated to said first layer, said layers having the following characteristic properties:
(a) The first layer, that is to say the actual reinforcing layer (or "supporting layer" in the terminology of the present invention) is to have a comparatively high modulus of elasticity of between 30 and 500 kg/mm2, after appli-cation on-to the me-tal plate and curing.
It is clearly disclosed in said reference, that this layer takes care of the very task of stiffening~
(b) The second layer, that is to say the adhesive layer for fixing -the actual reinforcing layer on the panel to be re-inforced, is to have a comparatively low modulus of elasti-2~ 735 city of between O.l and 22 kg/mm .
In said reference, it is emphasized expressis verbis thatthe modulus of elasticity oE this adhesive layer is to be so low that it is insufficient for stiffening the panel.
In this way, it is possible to avoid a visible deformation of the panel to be reinforced, for example of a sheet metal part of a car, such as a door, a deck lid~ et cetera. Moreover, the outer first layer, which has a comparatively high modulus of elasticity, brings about the actual reinforcing effect. The second layer facing the panel to be reinforced, that is to say the adhesive layer, has such a low modulus of elasticity that it cannot deform the panel -to be reinorced.
The main disadvantage of this arrangement is that the rein-forcing effect is rather poor because of -the comparatively low modulus of elasticity of the adhesive layer. A joint between the actual reinforcing layer and the panel to be reinforced, which is stiff against shearing) cannot be made in this way.
OBJECTS OE THE INVENTION
It is the object oE the present invention to provide a mul-ti-layer sheet structure for the reinforcement of panels made e.g. of sheet metal or plastic Inaterial which multi layer sheet structure, on the one hand, provides an improved reinEorcing and stiffening of said panel and, on the other hand, excludes any deformation of said panel after curing said multi-layer sheet structure.
S~MMARY OF THE INVENTION
The invention provides a multi-layer sheet structure for the reinforcement of panels. The sheet structure includes a supporting layer and an adhesive layer applied on said supporting layer on the side facing the panel to be reinforced.
The supporting layer comprises a curable plastic material and a reinforcing material combined with or embedded in said curable plastic material. The supporting layer is determined, before curing, to have, after curing, a coefficient of thermal expansion which is essentially the same as the coefficient of thermal expansion of the panel to be reinforced. The adhesive layer comprises a curable plastic material optionally provided with fillers or other additives, and said adhesive layer is determined, before curing, to have, after curing, a modulus of elasticity which is higher than the modulus of elasticity of th~
cured plastic material of said supporting layer.
The invention further provides a method for the reinforcement of panels by means of a multi-layer sheet structure. Thereby, in a first step, the coefficient of thermal expansion of the panel to be reinforced is determined~ In a second step, a supporting layer comprising a curable plastic material and a reinforcing material combined with or embedded in said curable plastic material is prepared, the ratio of the plastic material to the reinforcing material being chosen in a manner that the ~
2 ~ 3 ~
supporting layer, after curing, has a coefficient of thermal expansion ~hich is essentially the same as the coef~icient of thermal expansion of the panel to be rein~orced.
In a third step, an adhesive layer comprising a curable plastic material is applied onto said supporting layer, said adhesive layer, after curing of said plastic material, having a modulus of elasticity which is higher than the modulus of elas-ticity of the cured plastic material of said supporting layer.
In a four-th step, the multi-layer sheet structure obtained by the second and third steps is fixed onto said panel to be reinforced, with the side of said adhesive layer facing said panel to be reinforced. In a fif~h, final step, the fixed mul-ti-layer sheet structure is treated so as to cure the plastic materials of said supporting layer and said adhesive layer and to firmly bond said multi-layer sheet structure with said panel to be reinforced.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a sectional view of a multi-layer sheet structure of the invention in its unused state.
Fig. 2 to ~ are sectional views of three composites com-prising multi-layer sheet structures oE the invention and show-ing nega-tive, zero and positive deElection, respectively.
DETAILED DESCRIPTION OF THE INVENTION
The ~erm "modulus of elasticity" signifies, throughout the description and the claims, the modulus of elasticity deter-mined by the tensile test.
The tests made by the Inventors clearly show that deforma-tion of, for example, a sheet metal is in the first place caus-ed by the different coefficients of thermal expansion of the two materials - in the case of said example of the metal panel to be reinforced and the plastic material used for stiffening -when the arrangement is cooled after heat-curing. Obviously, volume contraction is of secondary importance, since it takes place above the glass transition region where forces can scar-cely be transmitted.
In this manner, a multi-layer sheet structure having, for example, two layers can be built up so that after its applica-tion onto the sheet metal $o be reinforced and its curing a composite of shee-t metal/adhesive layer/reinforcing layer is obtained which is symmetrical with respect to its thermal ex-pansion. It is a matter of course that the reinforcing layer is to have the same coefficient of thermal expansion as the slleet metal to be reinforced. Under these preconditions, the sheet metal on the one hand, and the reinforcing layer on the other hand will symmetrically contract during the cooling process so that no deformations of the sheet metal can occur. The contrac-tion of the adhesive layer, because of the symmetry present, is compensated in itself and does not have any detrimental effect to the shape or the appearance of -the sheet metal.
2 01~11S~7~
The coeEficient of thermal expansion of the supporting layer can be adjusted within a wide range to that of the panel to be rein~orced, due to the feature -that the adhesive layer, after curing the resin material contained in said supporting layer, has a higher modulus of elas-ticity than the cured resin material of said supporting layer, and due to the fact that the resin material used for said supporting layer can freely be combined with reinforcing materials. On the other hand, the colnbination "resin material o~ the supporting layer + reinforc-ing material" has a higher modulus of elasticity than the ad-hesive layer. By this, it is ensured, particularly if the dif-ferences with respect to the moduli of elasticity of said ad-hesive layer on the one hand and oE said supporting layer on the other hand are not too important, that a link is created between said supporting layer and said panel to be stiffened which is stiff against shearing. This also ensures a pronounced stiffening and reinforcing effect onto the panel.
The coefficient of thermal expansion can very easily be controlled by means of the volu.me ratio of resin material to reinforcing material.
Glass cloth is particularly sui-table as reinforcing mate-rial. It turned out that in the case of stiffening a steel sheet (which probably is the most frequent case in practice) a ratio of glass cloth to resin material of, roughly spoken, 50:50 by weight, and preEerably of about 48:52 by volume, is to be aimed at.
IJI practice, for stiffening a panel in accordance with the present invention, one proceeds as follows:
~ 3 ~
First, th~ coefficient of thermal expansion o~ the panel to be reinforced is determined.
Then, a supporting layer comprising a curable resin materi-al and a reinforcing material combined therewith or embedded therein is produced, selecting the ratio of resin material to reinforcing material in such a manner that said supporting lay-er, after curing, has essentially the same coefficient o~ ther-mal expansion as the panel to be reinforced.
Thereafter, an adhesive layer is deposited onto said sup-porting layer, said adhesive layer comprising a curable resin material and having, after curing of said resin material, a total modulus of elasticity which is higher than that of the cured resin material o~ the supporting layer.
The multi-layer sheet structure prepared as described above is fixed onto the panel to be reinforced, the adhesive layer facing the panel to be reinforced, and said multi-layer sheet structure is treated, for example heat-treated, in order to cure the resin materials of said supporting layer and of said adhesive layer and to firmly combine said multi-layer sheet structure with the panel to be reinforced.
DESCRIPTION O~ PREFERRED EMBODIMENTS
The mul-ti-layer sheet structure shown in sec~ion in Fig. 1 was manufactured as explained below. The multi-layer sheet structure, as it is present before its application, is general-ly marked by the reference numeral "1" and has the following ;
.
5~73~
general structure:
The supporting layer 2 is made of a glass cloth 3, for ex-ample of a glass-fiber roving cloth having a speciEic gravity o~ 620 g/m . Said glass cloth 3 is embedded in a resin layer 4 consisting of a heat-curable resin. The following materials are most suitable:
- Compound a) 90 parts liquid epoxy resin (for example "Epikote 828"
of Shell) 10 parts dicyandiamide - Compound b) 90 parts diluted epoxy resin (for example "Epikote 215"
of Shell) 10 parts dicyandiamide ~ ~
60 parts solid epoxy resin (Eor example "Epikote 1001"
of Shell) 5 parts dicyandiamide 35 parts dimethylketone (serving as a solvent for the impregnation and being afterwards evaporated) The modulus of elasticity of the cured resin is adjusted to a value of 2100 N/mm2 by suitable selection of the resin ma-terial and the fillers. The percentage of the glass in layer 2 was varied as explained hereafter. The thickness of layer 2 was jt73~
about 0.6 mm.
An adhesive layer 5, which essentially consisted of a heat-curable self-adhering resin, was applied to said layer 2. The following materials are most suitable:
- Compound a) 30 parts liquid epoxy resin (for example "Epikote 828"
of Shell) 20 parts solid epoxy resin (for example "Epikote 1001"
of Shell) 4 par~s dicyandiamide 20 parts talcum 26 parts fly ash ("Fillite") 35 parts liquid epoxy resin (for example "Epiko-te 828"
of Shell) 25 parts solid epoxy resin ~for example "Epikote 1001"
of Shell) 5 parts dicyandiamide 5 parts mica 30 parts talcum The modulus o~ elasticity o~ the cured resin was adjusted to a value of 3700 N/mm2 by suitable selection of the resin ma-terial and the fillers. This value was clearly higher than the modulus of elasticity of the resin used for layer 2. The thick-ness of layer 5 was about 0.6 mm.
~ ~ O ~ 3 5 On the other hand, the modulus of elasticity of the cured layer 2, that is to say of the combination of resin and glass cloth, varied depending on the percentage of glass, but was at least 5000 N/mm . Particularly, the coefficient of thermal expansion can by varied by varying the ratio by volume of resin to glass cloth.
The back side of layer 2 was covered by an aluminium sheet 6 having a thickness of 20 um, whereas the front side of layer 5, when the multi-layer sheet structure l was unused, was covered by a removable protecting paper 7.
COMPARATIVE TESTS
The following tests were made with this multi-layer sheet structure:
TEST l A flat strip of steel sheet 8 having a length of 400 mm, a width of 25 mm and a thickness of 0.75 mm was provided wi-th a multi-layer sheet structure 1 in the manner described above and shown in Fig. l. The total thickness of said multi-layer sheet structure l was l.6 mm. The percentage by volume of glass cloth 3 in the layer 2 of multi-layer sheet structure l was 51 %.
After application, the composite of steel sheet 8 and multi-layer sheet structure l was heat-treated at 180C for 30 min-utes. The resulting deflection dl of the composite towards Z ~ ~7 3~
the sheet metal was 1.8 mm (shown very exaggeratedly in Fig.
2). This is due to the fact that the coe~ficient of thermal expansion of the reinforcing layer 2 of ~he mul-ti-layer sheet structure 1 was lower than that of the steel sheet strip 8.
The same experimental setup as in Tes-t 1 was used with the difference that the percentage by volume of glass cloth 3 in layer 2 of the multi-layer sheet structure 1 was 48 %. As shown in Fig. 3, the composite of steel sheet 8 and multi-layer sheet structure 1 did not distort9 that is to say that any eventual deformation was below the accuracy of measurement of 0.1 mm.
The same experimental setup and the same conditions as in Test 1 were used with the difference that the percentage by volume of glass cloth 3 in layer 2 of the multi-layer sheet structure 1 was 44 %. The resulting deflection d2 of the com-posite of steel sheet 8 and multi-layer sheet structure 1 to-wards the multi-layer sheet structure was 2.6 mm (shown very exaggeratedly in Fig. 4). This is due to the fact that the co-efficient of thermal expansion of the reinforcing layer 2 of multi-layer sh0et structure 1 was higher than that of the steel sheet strip 8.
21D~:115~35 A sample of the multi-layer sheet structure of Test 2 having the dimensions of 80 x 80 mm was applied onto a steel sheet having the dimensions of 200 x 200 x 0.75 mm. No de1ection could be detected wi-th the naked eye after heat-treatment at 180C for 30 minutes.
A steel sheet strip without an applied multi-layer shee~
structure 1 having a length of 150 mm, a width of 25 mm and a thickness of 0.75 mm was symmetrically supported at a distance of 100 mm. Then, the force Fo, acting onto the center of the sample, which is necessary for deflecting said steel sheet strip by 10 mm, was determined. AEterwards, the test was re-peated by using a steel sheet strip of the same dimensions but provided with a multi-layer sheet structure according to Test 1. Th0 force necessary for deflecting said re.inforced steel sheet strip by 10 mm was Fv. The reinforcing factor, that is to say FV/Fo, was 9 4.
.
A steel sheet strip without a multi-layer sheet structure 1 applied onto it, having a length of 150 mm, a width of 25 mm ~ O O~j7 3 5 and a thickness of 0.75 mm was symmetrically supported at a distance of 100 mm. Then, the force Fo, acting onto the cen-ter oE the sample, which is necessary for deflecting said steel sheet strip by 10 mm was de-termined. Afterwards, -the test was repeated by using a steel sheet strip of the same dimensions but provided with a multi-layer sheet structllre according to Test 2. The force necessary for deflecting said reinforced steel sheet s-trip by 10 mm was Fv. The reinforcing factor, that is to say FV/Fo, was 9.1.
A steel sheet strip w;thou-t a multi-layer sheet structur~ 1 applied onto it, having a length of 150 mm, a width of 25 mm and a thickness of 0.75 mm was symmetrically supported at a distance of 100 mm. Then, the force Fo, acting onto the cen-ter of the sample, which is necessary for deflecting said steel sheet strip by lO mm was determined. Afterwards, the test was repeated by using a steel sheet strip of the same dimensions but provided with a multi-layer sheet structure according to Test 3. The force necessary for deflecting said reinforced steel sheet strip by 10 mm was Fv. The reinforcing factor, that is to say FV/Fo, was 9.l.
~5~735 CONCLUSIONS
The conclusions which can be drawn Erom these tests may be summarized as follows:
1. All tests (1 to 3 and 5 to 7) fundamentally showed a dis-tinctly better reinforcing effect onto the steel sheet sam-ple than reported by the prior art (for example in said EP-Bl-0,053,361).
2. No deformation of the steel sheet sample could be observed if the supporting layer and adhesive layer were designed in accordance with the present invention, as evidenced by Tests 2 and 6.
; 3. lf the supporting layer and adhesive layer were designed in accordance with the present invention, only an insignificant decrease of the reinforcing factor could be observed (9.1 against 9.4 in Tests 5 and 6).
Claims (23)
1. A multi-layer sheet structure for the reinforcement of a panel having a coefficient of thermal expansion x, said sheet structure including a supporting layer and an adhesive layer applied on said supporting layer on the side facing the panel to be reinforced;
said supporting layer comprising a curable plastic material and a reinforcing material combined with or embedded in said curable plastic material, and said supporting layer determined, before curing, to have, after curing, a coefficient of thermal expansion which is essentially x;
said adhesive layer comprising a curable plastic material optionally provided with fillers or other additives, and said adhesive layer determined, before curing, to have, after curing, a modulus of elasticity which is higher than the modulus of elasticity of the cured plastic material of said supporting layer.
said supporting layer comprising a curable plastic material and a reinforcing material combined with or embedded in said curable plastic material, and said supporting layer determined, before curing, to have, after curing, a coefficient of thermal expansion which is essentially x;
said adhesive layer comprising a curable plastic material optionally provided with fillers or other additives, and said adhesive layer determined, before curing, to have, after curing, a modulus of elasticity which is higher than the modulus of elasticity of the cured plastic material of said supporting layer.
2. A multi-layer sheet structure according to claim 1, wherein said adhesive layer comprises an epoxy resin.
3. A multi-layer sheet structure according to claim 1, wherein said adhesive layer is self-adhesive.
4. A multi-layer sheet structure according to claim 2, wherein said adhesive layer comprises a heat-curable one-com- ponent formulation.
5. A multi-layer sheet structure according to claim 1, wherein said adhesive layer comprises an epoxy resin and one or more fillers of the group consisting of talcum, chalk, mica, silicates, aluminium oxide, fly ash, hollow glass marbles, and glass marbles.
6. A multi-layer sheet structure according to claim 1, wherein said adhesive layer has a modulus of elasticity of bet-ween 2500 and 6000 N/mm2.
7. A multi-layer sheet structure according to claim 6, wherein said adhesive layer has a modulus of elasticity of bet-ween 3000 and 4500 N/mm2, preferably of between 3500 and 4000 N/mm2.
8. A multi-layer sheet structure according to claim 1, wherein said adhesive layer has a thickness of 0.3 to 2.0 mm, preferably of about 0.7 mm.
9. A multi-layer sheet structure according to claim 1, wherein said supporting layer comprises a plastic material which, after curing, has a modulus of elasticity of less than 2500 N/mm2.
10. A multi-layer sheet structure according to claim 9, wherein said supporting layer comprises a plastic material which, after curing, has a modulus of elasticity of 1800 to 2400 N/mm2, preferably of about 2100 N/mm2.
11. A multi-layer sheet structure according to claim 1, wherein said supporting layer comprises a glass cloth impreg-nated with said curable plastic material.
12. A multi-layer sheet structure according to claim 1, wherein said supporting layer comprises a layer of curable plastic material in which a glass cloth is embedded.
13. A multi-layer sheet structure according to claim 1, wherein said supporting layer comprises a layer of curable plastic material onto which a glass cloth is pressed on.
14. A multi-layer sheet structure according to any one of claims 11 to 13, wherein the ratio of glass cloth to curable plastic material is from 40:60 to 60:40, by volume.
15. A multi-layer sheet structure according to claim 14, wherein the ratio of glass cloth to curable plastic material is from 45:55 to 55:45, by volume.
16. A multi-layer sheet structure according to claim 14, wherein the ratio of glass cloth to curable plastic material preferably is 48:52, by volume.
17. A multi-layer sheet structure according to claim 1, wherein the cured supporting layer has a modulus of elasticity which is higher than the modulus of elasticity of the cured adhesive layer.
18. A multi-layer sheet structure according claim 17, wherein the cured supporting layer has a modulus of elasticity which is higher than 5000 N/mm2.
19. A multi-layer sheet structure according to claim 1, wherein the cured supporting layer has a thickness of 0.1 to 2.0 mm, preferably of 0.3 to 0.8 mm.
20. A method for the reinforcement of panels by means of a multi-layer sheet structure according to claim 1, said method comprising the following steps:
(a) Determining the coefficient of thermal expansion of the panel to be reinforced;
(b) Preparing a supporting layer comprising a curable plastic material and a reinforcing material combined with or em-bedded in said curable plastic material, the ratio of said plastic material to said reinforcing material being chosen in a manner that said supporting layer, after curing, has a coefficient of thermal expansion which is essentially the same as the coefficient of thermal expansion of the panel to be reinforced;
(c) Applying onto said supporting layer an adhesive layer com-prising a curable plastic material, said adhesive layer, after curing of said plastic material, having a modulus of elasticity which is higher than the modulus of elasticity of the cured plastic material of said supporting layer;
(d) Fixing the multi-layer sheet structure obtained by steps (b) and (c) onto said panel to be reinforced, with the side of said adhesive layer facing said panel to be reinforced;
(e) Treating the fixed multi-layer sheet structure so as to cure the plastic material of said supporting layer and said adhesive layer and to firmly bond said multi-layer sheet structure with said panel to be reinforced.
(a) Determining the coefficient of thermal expansion of the panel to be reinforced;
(b) Preparing a supporting layer comprising a curable plastic material and a reinforcing material combined with or em-bedded in said curable plastic material, the ratio of said plastic material to said reinforcing material being chosen in a manner that said supporting layer, after curing, has a coefficient of thermal expansion which is essentially the same as the coefficient of thermal expansion of the panel to be reinforced;
(c) Applying onto said supporting layer an adhesive layer com-prising a curable plastic material, said adhesive layer, after curing of said plastic material, having a modulus of elasticity which is higher than the modulus of elasticity of the cured plastic material of said supporting layer;
(d) Fixing the multi-layer sheet structure obtained by steps (b) and (c) onto said panel to be reinforced, with the side of said adhesive layer facing said panel to be reinforced;
(e) Treating the fixed multi-layer sheet structure so as to cure the plastic material of said supporting layer and said adhesive layer and to firmly bond said multi-layer sheet structure with said panel to be reinforced.
21. A method according to claim 20, wherein the plastic materials used in said supporting layer and in said adhesive layer are heat-curable.
22. A method according to claim 20 or 21, wherein said multi-layer sheet structure, after having been fixed to said panel to be reinforced, is subjected for 15 to 60 minutes, pre-ferably for 30 minutes, to a temperature of 80 to 240°C, pre-ferably of 150 to 200°C, in order to cure the heat-curable plastic material of said supporting layer and of said adhesive layer.
23. Reinforced panel, preferably made of steel or aluminium sheet metal or of plastic material, provided with a multi-layer sheet structure according to any one of claims 1 to 19.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE3844284A DE3844284C1 (en) | 1988-12-30 | 1988-12-30 | |
| DEP3844284.1 | 1988-12-30 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2005735A1 true CA2005735A1 (en) | 1990-06-30 |
Family
ID=6370499
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002005735A Abandoned CA2005735A1 (en) | 1988-12-30 | 1989-12-15 | Multi-layer sheet structure for the reinforcement of panels, a method for the reinforcement of panels and a reinforced panel |
Country Status (6)
| Country | Link |
|---|---|
| EP (1) | EP0376880A3 (en) |
| JP (1) | JPH02227245A (en) |
| KR (1) | KR900009275A (en) |
| CA (1) | CA2005735A1 (en) |
| DE (1) | DE3844284C1 (en) |
| ZA (1) | ZA899552B (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7238407B2 (en) | 2002-10-30 | 2007-07-03 | Henkel Kommanditgesellschaft Auf Aktien | Multi-layer reinforcing laminate |
| US7473717B2 (en) | 2001-12-21 | 2009-01-06 | Henkel Ag & Co. Kgaa | Expandable epoxy resin-based systems modified with thermoplastic polymers |
| US7736743B2 (en) | 2003-01-22 | 2010-06-15 | Henkel Kgaa | Heat curable, thermally expandable composition with high degree of expansion |
| EP3093222B1 (en) | 2008-08-12 | 2018-12-12 | Sika Technology AG | Structural reinforcement system |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2734271B1 (en) * | 1995-05-19 | 1997-07-18 | Nayad Diffusion | COMPOSITION FOR THE MANUFACTURE OF SOLID MATERIALS, IN PARTICULAR FOR USE IN THE MANUFACTURE OF SANITARY OBJECTS |
| DE10163252A1 (en) * | 2001-12-21 | 2003-07-10 | Henkel Teroson Gmbh | Surface stiffening rubber systems |
| DE102006002541B4 (en) * | 2006-01-18 | 2010-02-18 | Sven Hunze | Composite with visible fabric layer and manufacturing process |
| US8288447B2 (en) | 2006-06-07 | 2012-10-16 | Henkel Ag & Co. Kgaa | Foamable compositions based on epoxy resins and polyesters |
| CN113290957A (en) * | 2021-05-19 | 2021-08-24 | 业成科技（成都）有限公司 | Connecting belt microstructure and manufacturing method thereof |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6017705B2 (en) * | 1980-11-27 | 1985-05-04 | 日東電工株式会社 | Adhesive sheet for reinforcing metal plates and method for reinforcing metal plates |
| CA1190841A (en) * | 1981-01-21 | 1985-07-23 | Cecil L. Phillips | Composites and methods for providing metal clad articles and articles produced thereby |
| ATE15006T1 (en) * | 1981-01-21 | 1985-09-15 | Scott Bader Co | COMPOSITES AND PROCESSES FOR MANUFACTURING METAL COATED ARTICLES. |
| JPS57151361A (en) * | 1981-03-16 | 1982-09-18 | Nissan Motor | Reinforcing material and reinforcing panel |
| JPS60221477A (en) * | 1984-04-18 | 1985-11-06 | Nitto Electric Ind Co Ltd | Adhesive sheet for vibration damping and reinforcing |
| DE3720866A1 (en) * | 1986-06-24 | 1988-01-28 | Bridgestone Corp | Composite sheet metal |
-
1988
- 1988-12-30 DE DE3844284A patent/DE3844284C1/de not_active Expired - Lifetime
-
1989
- 1989-12-06 EP EP19890810921 patent/EP0376880A3/en not_active Withdrawn
- 1989-12-14 ZA ZA899552A patent/ZA899552B/en unknown
- 1989-12-15 CA CA002005735A patent/CA2005735A1/en not_active Abandoned
- 1989-12-26 JP JP1338018A patent/JPH02227245A/en active Pending
- 1989-12-29 KR KR1019890020192A patent/KR900009275A/en not_active Application Discontinuation
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7473717B2 (en) | 2001-12-21 | 2009-01-06 | Henkel Ag & Co. Kgaa | Expandable epoxy resin-based systems modified with thermoplastic polymers |
| US7238407B2 (en) | 2002-10-30 | 2007-07-03 | Henkel Kommanditgesellschaft Auf Aktien | Multi-layer reinforcing laminate |
| US7736743B2 (en) | 2003-01-22 | 2010-06-15 | Henkel Kgaa | Heat curable, thermally expandable composition with high degree of expansion |
| EP3093222B1 (en) | 2008-08-12 | 2018-12-12 | Sika Technology AG | Structural reinforcement system |
Also Published As
| Publication number | Publication date |
|---|---|
| DE3844284C1 (en) | 1990-04-05 |
| JPH02227245A (en) | 1990-09-10 |
| EP0376880A2 (en) | 1990-07-04 |
| EP0376880A3 (en) | 1991-07-31 |
| KR900009275A (en) | 1990-07-04 |
| ZA899552B (en) | 1990-09-26 |
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