Structural components made from a fibrous reinforcing support and rubber and methods for their manufacture

Structural components are produced which have at least 2 layers A and B. Layer A contains, as a matrix, a thermoplastic resin plastic containing a polyphenylene ether and fibrous reinforcing supports disposed therein. Layer B is a rubber which is obtained through the vulcanization of certain caoutchoucs containing double bonds.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The invention relates to structural components made from at least two 
securely adhering layers A and B, one of which is made from a fibrous 
reinforcing support and a thermoplastic resin and the other of which is 
made of rubber, as well as to methods for the manufacture of such 
structural components. 
2. Discussion of the Background 
It is known that a single material cannot always have all of the 
characteristics expected of an object. For example, high strength, 
rigidity or hardness on the one hand, and good oscillation dampening, 
malleability or skid resistance on the other, are not compatible. If an 
item is intended to possess all of these characteristics, composites of 
several materials are used. 
An obvious solution in this case is a composite of metal and rubber. 
This combination, however, has two important disadvantages: 
1. Metals have a high density, i.e. the structural components made 
therefrom are heavy. 
2. Metal and rubber are not easily bonded and providing the metal with an 
adhesion enhancer is difficult. 
Composites between caoutchouc and glass or aramide fibers are known (see W. 
Kleeman "Mischungen fuer die Elastverarbeitung," VEB, Deutscher Verlag 
fuer Grundstoffindustrie, Leipzig, 1982, Chapter 20, pp. 296 et seq.). 
However, these systems do not provide for the manufacture of rigid plates 
or other rigid elements of any desired shape. It is also known to treat 
glass fibers with gamma-aminopropyltrimethoxysilane and then to inclose 
them in thermosetting plastics, such as formaldehyde-resorcinol copolymers 
or polyurethanes. In the last step, a composite with caoutchouc is 
achieved, for example, with the use of vinylpyridine copolymers. 
Thermosetting plastics, once they have hardened, are no longer deformable. 
Yet, for many applications this restriction is unsatisfactory. 
Carbon fiber reinforced thermoplastic resins are described, for example, in 
the book, Developments in Reinforced Plastics -4, Elsevier Applied Science 
Publishers, 1984, by Paul E. McMahon. It is recognized that the systems 
described there would meet the above-described requirements, if the 
reinforced thermoplastic resin was to engage in a solid bond with 
caoutchouc. Examination shows that this is not the case. The vulcanized 
caoutchouc can be pulled away from the surface of the thermoplastic resins 
with a small force, i.e. less than 0.7 N/mm in the case of a composite of 
carbon fibers, polyether ether ketone, and E-SBRcaoutchouc. Therefore, 
according to the prior art, it is not possible to manufacture structural 
components of (a) thermoplastic resin and reinforcing fibers and (b) 
caoutchouc in a simple manner. 
SUMMARY OF THE INVENTION 
Accordingly, one object of the present invention is to provide composite 
structural components which exhibit high strength, rigidity and hardness 
and also good oscillation dampening, malleability and skid resistance. 
Another object of the invention is to provide a composite material 
comprised of rubber and a thermoplastic resin reinforcing support which 
contains fibers, in which the rubber is solidly bonded to the support. 
These and other objects which will become apparent from the following 
specification have been achieved by the structural component of the 
present invention which comprises (a) a support layer comprising a fibrous 
reinforcing support which comprises uncut non-metallic fibers and a matrix 
which comprises a polyphenylene ether or a thermoplastic resin which 
contains a polyphenylene ether and (b) a vulcanized rubber, wherein the 
structural component is produced by covulcanization of the support layer 
and the rubber. 
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
It has now been found that a combination of characteristics can be attained 
in structural components which are made from two layers A and B. 
Solid layer A consists of uncut, non-metallic fibers coated with a 
thermoplastic resin containing polyphenylene ether (PPE). The 
thermoplastic resin can be either a thin coating or have the form of a 
matrix in which the fibers are embedded. 
Layer B is comprised of rubber obtained through the vulcanization of 
caoutchouc containing double bonds. U.S. appliction Ser. No. 831,449, 
filed Feb. 20, 1986, now abandoned and refiled as continuation application 
Ser. No. 115,567, filed Oct. 29, 1987 discloses a "Method for the 
Manufacture of a Chemical Composite Between Shaped Objects Based on 
Polyphenylene Ethers on the One Hand and Caoutchoucs Vulcanized with 
Sulphur and Containing Double Bonds on the Other Hand." However, this 
application provides no suggestion that non-metallic fibers can be used in 
the composite. In addition, it is important that the fibers are uncut, 
since cut fibers are used almost exclusively for thermoplastic resins. 
Finally, the proportion of fibers is in no way limited to 50%. 
The thermoplastic resin of the layer A contains polyphenylene ether as its 
most important component, and can also contain flow enhancers and other 
additives. 
A preferred polyphenylene ether is a polyether based on 2,6-dimethylphenol, 
in which the ether oxygen of one unit is bonded to the benzene ring of the 
adjacent unit. At least 50 such units should be connected with each other. 
Of course, other o,o'-dialkylphenols can be used. The alkyl substituents 
have at most 6 carbon atoms, and should not have a tertiary carbon atom in 
the .alpha.-position relative to the ring. Also suitable are phenols which 
are substituted in one ortho-position with a tertiary alkyl group, 
particularly with a tertiary butyl group. Each of the monomeric phenols 
listed can be substituted with a methyl group in the 3 position, and 
optionally also in the 5 position. Mixtures of the monomeric phenols can 
also be used. The polyphenylene ethers can be manufactured from the 
phenols, for example in the presence of complex-forming agents such as 
copper bromide and morpholine (see DE-0S 32 24 692 and OS 32 24 691). The 
viscosity value J, which is determined according to DIN 53 728 in 
chloroform at 25.degree. C lies in the range from 25 to 90 cm.sup.3 /g. 
Preferred is the polymer of 2,6-dimethylphenol, i.e., 
poly-(2,6-dimethyl-1,4-phenylene-ether). 
Low molecular weight compounds such as ester plasticizers or aromatics 
which are soluble in PPE can be added to the PPE in quantities up to 50%, 
preferably up to 20%, as flow enhancers. 
Preferred ester plasticizers are organic esters of phosphorous acid; 
organic esters of phosphoric acid; phthalic acid esters, with alcohols 
having up to 15 carbon atoms; esters of aliphatic or aromatic dicarboxylic 
acids having aliphatic or aliphatic-aromatic alcohols; and oligoesters of 
the above-described acids with diols, whereby the maximum proportion of 
the diol is 20%, relative to the quantity of monomeric ester. 
Preferred aromatics are compounds having up to 5 aromatic rings and 
optionally, other functional groups. Examples include benzyl toluene, 
dibenzyl toluene, toluene and xylene. 
Other additive agents include polymeric additives, such as known impact 
resistance enhancers for PPE. Preferred are polyoctenylenes, 
styrene-butadiene-styrene block copolymers and styrene polymerisates 
modified with regard to their impact resistance. Homopolystyrene 
polymerisates can also be added. However, as a rule the desired composite 
is not improved by these types of additives. Therefore, the proportion of 
these additives is preferably less than 20%. 
The fibrous reinforcing support consists of uncut, nonmetallic fibers such 
as carbon, aramide or glass fibers. The fibers can be present, for 
example, in the form of yarns, weaves, mats, felts, rovings or as 
individual fibers. The glass fibers are generally treated with a fiber 
coating by the manufacturer. 
The shape and size of the bonded layers in the structural component can 
vary widely. They can be practically identical, as in sandwich structures, 
or they can be unequal, as in large surface area rubber mats with 
reinforced edge areas or as in large-surface area rigid elements with 
rubber feet. The size and shape of the layers A and B is thus not 
important. All that matters is that the layers A and B are connected with 
each other at a common, uninterrupted surface if possible. The structural 
components must consist of at least 2 layers A and B. But 3 or more layers 
preferably in an alternating sequence such as ABAB or BABA, etc., can also 
be provided. Example 1, for instance, describes composite plates of 
rubber, and a thermoplastic resin containing PPE and wrapped in carbon 
fibers. 
The stiffness and strength of layer A is determined by the type, 
arrangement and quantity of the fibrous reinforcing supports and by the 
composition of the matrix. 
The following caoutchoucs vulcanized with sulphur and containing double 
bonds are suitable as component B. All of these are disclosed in German 
Patent Application P 36 02 705.7: 
(1) Styrene-butadiene-caoutchouc 
This can involve both E- and L-SBR-caoutchouc having a styrene component of 
between 18-40 percent by weight. Oil-extended SBR caoutchoucs are also 
suitable. The caoutchouc can be present in bead form. It is more 
economical, however, to use a powdered caoutchouc containing a filler. 
E-SBR caoutchouc is manufactured in a known manner by emulsion polymerizing 
from 15-40 percent by weight styrene and a corresponding quantity of 85-60 
percent by weight butadiene. A caoutchouc of this type is described, for 
example, in the trade magazine BUNA.RTM. EM No. 601 of the Bunawerke Huels 
GmbH, September 1982 edition. Its Mooney-viscosity ML.sub.(1+4), 
100.degree. C., lies between 30-120 (see Mooney, Rubber Chem. Techn. 30, 
460 (1957)). 
The covulcanizable caoutchouc mixtures always contain fillers such as 
carbon black or silicic acid, extender agents such as mineral oils, 
vulcanization agents such as sulphur, vulcanization accelerators and aging 
prevention agents. A particularly preferred processing enhancer is 
polyoctenylene (A. Draexler, Kautschuk +Gummi, Kunststoffe 1983, pp. 1037 
to 1043). 
The added mineral oils can be paraffinic, naphthenic or aromatic. 
(2) Butadiene-Caoutchouc 
BR-caoutchoucs are preferable regardless of whether they were manufactured 
with Li or Co catalysts. In addition, the quantity of the cis-1,4-isomer 
has no influence on the suitability of the type of caoutchouc. The use of 
polyoctenylene as a processing enhancer is also preferred here. 
(3) Polyisoprene 
Synthetic IR-caoutchoucs are preferred, regardless of whether they were 
manufactured with Ti or Li catalysts. 3,4-IR caoutchoucs can also be used. 
Accrrdingly, the cis-1,4/trans-1,4 or 1,2- and 3,4-content has no effect 
on the adhesion characteristics. 
(4) Isobutene-isoprene-caoutchoucs 
IIR caoutchoucs are also directly suitable. Halogenated varieties require 
additional mixture components. 
(5) Mixtures of the following caoutchouc types with each other: SBR 
(styrene-butadiene caoutchouc), BR (butandiene caoutchouc), IR (isoprene 
caoutchouc) and IIR (isoburene-isoprene caoutchouc). 
These mixtures preferably have 2 or 3 components. Especially good results 
are achieved with mixtures of different weight components of SBR and BR 
caoutchouc. 
(6) Caoutchouc mixtures containing NR (natural caoutchouc), CR (chloroprene 
caoutchouc), NBR (acrylonitrile-butadiene caoutchouc) and/or CIIR 
(chlorinated isobutylene-isoprene caoutchouc). 
These are mixtures of the caoutchouc components 1 through 5 with the 
above-listed caoutchouc types, whereby the proportion of the latter can 
total as much as 80 percent by weight. 
The styrene-butadiene-caoutchouc according to (1) is particularly preferred 
for the method according to the invention. 
The manufacture of the listed types of caoutchoucs takes place according to 
methods known in the literature (see W. Hofmann, Kautschuktechnologie, 
Gentner-Verlag, Stuttgart, 1980). 
The caoutchouc surfaces can be treated, for example, in accordance with the 
method disclosed in EP-OS 0 141 087. 
The manufacture of the structural components basically takes place in 2 
steps. First, the layer A is produced, and subsequently, the structural 
component is manufactured through covulcanization with the caoutchouc. 
In the first step the fibrous reinforcing supports are saturated with a 
solution of the thermoplastic resin. Any solvent is suitable which is 
capable of dissolving the polyphenylene ether, i.e., even chlorinated 
hydrocarbons. Solvents are preferred which evaporate easily, such as 
toluene, xylene, or benzene. The solvent is then removed, and layer A is 
shaped either simultaneously therewith or subsequent thereto. This 
preferably takes place at an elevated temperature and in some cases under 
vacuum or excess pressure. In the case of rovings, the manufacture of the 
layer A includes the following method steps: 
(1) Submersion and saturation with a solution of the matrix material, 
(2) Extension until the fibers are parallel, 
(2a) In some cases, placement or coiling the saturated rovings, 
(3) Drying, 
(3a) In some cases, heating and shaping above the softening temperature, 
optionally under pressure, 
(4) In some cases, coating the reinforcing support with PPE through a 
thermoplastic processing method. 
In some cases it is advisable to repeat the saturation and removal of the 
solvent. With woven fabric or felts, for example, a homogenous 
interlocking of the fibers can be assured by manipulating or squeezing 
them. 
Dissolving the thermoplastic resins in the following manner is particularly 
preferred. The toluene solution occurring due to the oxidative coupling of 
2,6-dimethylphenol is freed of residual catalyst in a known manner, flow 
enhancer and other additives are added if desired, and is then thinned or 
thickened to the concentration which is most favorable for the saturation 
of the fibrous reinforcing support. Of course, the solution can also be 
produced by dissolving solid PPE in the solvent. Saturated solutions 
having a relatively low PPE concentration, such as 5 percent, are 
particularly preferred for the manufacture of layers with a high 
proportion by weight of reinforcing fiber. High-percentage solutions, such 
as 50% solutions, are particularly well suited for the manufacture of 
layers with a high proportion by weight of thermoplastic resin. 
The production of the structural components which are comprised of rigid 
and rubber-elastic layers can take place in various ways, such as by 
compression under vulcanization conditions, by extrusion coating of 
prepared rovings or prefabricated rigid shaped elements with caoutchouc 
and vulcanization, or by the spraying of prefabricated rigid elements 
under vulcanization conditions. 
The caoutchouc used in the structural components can be reinforced by known 
means, such as by casings. Additional auxiliary items such as spacers, 
clamps or supports made from reinforced or unreinforced PPE can also be 
used. When used, these items are still in place during vulcanization and 
are lost for future use, remaining in the structural component. 
Additives 
Carbon Fibers: Commercial carbon fiber rovings E/XA-S 12 K of the company 
Hysol Grafil Ltd., Coventry, England. 
Aramide Cord: Commercial filament yarn of Kevlar 49 from Du Pont Co., 
CH-1211 Geneva 24, Switzerland. 
Glass Fibers: Commercial VETROTEX.RTM.--Textile glass Roving EC-10-9600-P 
388 from the company Gevetex Textilglas-GmbH, D5100 Aachen. 
PPE: PPE dissolved in toluene, such as is provided in accordance with DE-OS 
33 13 864 after the reaction extraction. The viscosity values of the 
polymers (determined in chloroform according to DIN 53 728) are given 
respectively. 
TABLE 3 
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Proportions of the 
Mass Ratio - 
Reinforcement 
Viscosity value 
Thermoplastic Resin 
Reinforcement Separating Force 
Example No. 
Support of the PPE ml/g 
in the Saturation Bath 
Support:Thermoplastic 
N/mmn 
__________________________________________________________________________ 
A C Fiber -- -- -- 0.4 
1 C Fiber 25 PPE 15* 66:34 4.3 
2 C Fiber 59 PPE 15 62:38 9.2 
3 C Fiber 83 PPE 15 57:43 8.5 
4 C Fiber 59 PPE:TPP - 15:1.5* 
52.48 8.0 
5 C Fiber 59 PPE:TOR:DBT - 15:1.5:1.5 
54.46 6.3 
B Aramide Cord 
-- -- -- 0.67 
6 Aramide Cord 
59 PPE: 15 48:52 6.7 
7 Aramide Cord 
59 PPE:TOR:TPP - 15:1.5:1.5 
50:50 7.5 
C Glass Fiber 
-- -- -- 0.67 
8 Glass Fiber 
59 PPE 15 83:17 4.8 
9 Glass Fiber 
59 PPE:TOR:TPP = 15:1.5:1.5 
75:25 5.0 
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*The numbers indicate the % of the respective materials in the solution o 
the thermoplastic resin that are used in the saturation. 
Impact Resistance Agents: A polyoctenylene was used with a viscosity value 
of 120 ml/g and a transcontent of 80%. A product of this type is 
commercially available under the name VESTENAMER.RTM. 8012 (Manufacturer: 
Huels A.G., D- 4370 Marl 1). Additional characterizing data for this 
product can be obtained from the periodical "Kautschuk, Gummi, 
Kunststoffe" 1981, pp. 185 to 190, as well as from the Huels brochure No. 
2247, "VESTENAMER.RTM. 8012." The polyoctenylene can also be manufactured, 
for example, in accordance with K.J. Ivin "Olefin Metathesis," Academic 
Press, pp. 236 et seq., 1983, and the literature citations given therein. 
Flow Enhancers: Triphenyl phosphate (TPP) 
MARLOTHERM.RTM. S (DBT), a mixture of isomeric dibenzyl toluenes, 
commercial product of Huels A.G., D-4370 Marl 1. 
Caoutchoucs: A carbon-black filled, softener-containing E-SBR-powdered 
caoutchouc is manufactured by mixing the following components: 
______________________________________ 
Parts by Weight 
Material 
______________________________________ 
160 Powdered caoutchouc, consisting of 100 parts 
E-SBR-caoutchouc (styrene content 23 percent 
by weight) and 60 parts carbon black 
(company brochure of HUELS 
AKTIENGESELLSCHAFT, No. 5214 from 
October 1983 "Filler-containing Caoutchouc 
Powder BUNA .RTM. EM") 
1 Stearic acid 
4 Zinc oxide 
1 N--isopropyl-N'--phenyl-p-phenylene diamine 
1 N--(1,3-dimethylbutyl)-N'--phenyl-p- 
phenylene diamine 
2.5 a commercially available aging prevention 
agent against light and ozone (Antilux .RTM. 111). 
This is a paraffinic wax with broad molecular 
weight distribution and high molecular weight 
agents. (Manufacturer: Rhein-Chemie Co., 
D-6800 Mannheim). 
1.8 Sulphur 
1.3 N--cyclohexyl-1-benzothiazolsulphenamide 
0.8 Tetramethyl thiuramdisulphide 
0.5 Diphenyl guanidine 
0.3 zinc diethyl dithiocarbamate 
40 a common commercial aromatic mineral 
oil softener 
______________________________________ 
The mixture is rolled out within 5 minutes at 50.degree. C. to a 2 mm thick 
sheet. 
Other features of the invention will become apparent in the course of the 
following descriptions of exemplary embodiments which are given for 
illustration of the invention and are not intended to be limiting thereof.

EXAMPLES 
Example 1 
MANUFACTURE AND CHARACTERISTICS OF COMPOSITE PLATES MADE FROM A CARBON 
FIBER/PPE COMPOSITE AND CAOUTCHUOC 
1.1 Pretreatment of the Carbon Fibers 
The carbon fiber rovings are saturated in a 15% toluene solution of PPE 
(viscosity value=25 ml/g) heated to 70.degree. C, whereby the rovings in 
the solution are swelled by being crushed before they are brought back 
into parallel positions by being stretched out. The rovings that have been 
saturated in this manner are dried while lying straight at 100.degree. C. 
in a vacuum until constant weight is achieved. The ratio of carbon fibers 
to PPE is determined by comparative weighings. 
1.2 Plates Made from a Carbon Fiber/PPE Composite 
The treated strands are laid parallel and pressed into plates in a 
100.times.100.times.1 mm pressing frame at 300.degree. C. and 200 bar. 
1.3 Composite Plates with Caoutchouc 
One frontal side of the plate according to 1.2 is covered with a 20 mm wide 
strip of aluminum foil, which later serves as the separating means between 
the covulcanized layers and makes it possible to clamp the individual 
layers into the test apparatus. The plate is then coated with caoutchouc 
and the layers are covulcanized within five minutes at 180.degree. C. to a 
composite plate of 2 mm total thickness. 
1.4 Separation Test 
The composite plates are cut into 30 mm wide strips in the longitudinal 
direction of the fiber orientation and subjected to a separation test in 
accordance with DIN 53 539. 
1.5 Elasticity Module 
The elasticity modulus of the strips separated from the caoutchouc during 
the separation test in according to DIN 53 457 section 2.1. 
1.6 Effect on the Composite of Long-term Vibration Loads 
120.times.18 mm samples with a surface area of 10 mm are cut from the 
composite plates according to 1.3 and are subjected to a long-term 
vibration test in accordance with DIN 53 442 at a frequency of 10 Hz and a 
bending angle of 15.degree. 
1.7 Results 
The following characteristics were determined for EXAMPLE 1: 
TABLE 1 
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Separation Force N/mm 
Ratio of Separation After Long-term Vibration Tests 
Carbon Fibers to 
Force N/mm 
E modulus 
Numbers of Load Alterations 
Binding Agents 
According to 1.4 
N/mm 0 2 .multidot. 10.sup.6 
4 .multidot. 10.sup.6 
6 .multidot. 10.sup.6 
8 .multidot. 10.sup.6 
__________________________________________________________________________ 
66:34 4.3 190,000 
3.0 
3.0 4.8 4.1 4.4 
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EXAMPLES 2-9, COMISON EXAMPLES A-C 
The composition and experimental test data are shown in the Table 2. 
The plates and caoutchouc composites are prepared according to Example 1 
and subjected to a separation test according to DIN 53 539. For purposes 
of the comparison tests the fibers were not treated with the solution of a 
thermoplastic resin. 
EXAMPLES 10-15, COMISON EXAMPLES D-F 
Solutions of 
(I) 15% PPE of viscosity value 45 ml/g, or 
(II) 15% PPE of viscosity value 45 ml/g, 
1.5% VESTENAMER.RTM. 8012, and 1.5% triphenyl phosphate in toluene were 
used as the saturation agent for treatment of the rovings and cords. 
The reinforcing support was treated with the saturating agent, as described 
in Example 1, dried and tested for its adhesion strength to caoutchouc, 
which was vulcanized within 5 minutes at 180.degree. C. The method 
corresponds to the standard ISO/DIS 4679 of Dec. 7, 1979 (average value 
from 12 individual tests, H-test). 
TABLE 2 
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Reinforcing Saturation Adhesion 
Example No. 
Support Agent Strength 
______________________________________ 
D C Fiber Roving 
-- 31 
10 C Fiber Roving 
I 71 
11 C Fiber Robing 
II 79 
E Aramide Cord -- 35 
12 Aramide Cord I 47 
13 Aramide Cord II 55 
F Glass Fiber Roving 
-- 26 
14 Glass Fiber Roving 
I 52 
15 Glass Fiber Roving 
II 62 
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The structural components can be used in many ways. With a unidirectional 
alignment of the reinforcing support the primary uses are side protection 
elements for the automotive sector, such as side strips, door attachments, 
entry safety strips, and door sill scuff plates. An additional area for 
use is conveyor belts or air-filled tires, whereby the surfaces can be 
reinforced by casings in well-known ways. 
Areas of use in which the reinforcing supports are aligned orthotropically 
or quasi-isotropically relate to slip-resistant plates, and doors and 
flaps with sealing lips. 
Multiple sandwich structures of very thin layers of reinforcing supports 
and caoutchouc with a preferably quasiisotropic arrangement of the 
reinforcing support are used for light armor. 
The results of the comparison tests demonstrate that the adhesion strength 
values are reduced when a composite is manufactured of fibers and 
caoutchouc without thermoplastic resins. 
Obviously, numerous modifications and variations of the present invention 
are possible in light of the above teachings. It is therefore to be 
understood that within the scope of the appended claims, the invention may 
be practiced otherwise than as specifically described herein.