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(11) | EP 0 552 882 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Flat boat and framework for supporting canvas |
| (57) A small collapsible canoe or other boat is disclosed which includes a canvas stretched
over a knockdown frame formed from fiber-reinforced plastic tubes each containing
a synthetic fiber selected from a polyester fiber, a polyamide fiber, a polyethylene
fiber, a vinylon fiber and an aramide fiber as a reinforcing fiber. Each of the tubes
preferably has a specific gravity of 1.5 or less, a bending modulus of elasticity
of at least 40 ton/cm², an IZOD impact strength of at least 80 kg.cm and a duPont
impact strength of at least 0.2 kg x 500 mm. |
[0002] As a framework for a flatboat (small collapsible canoe), tubing material made of a heat resistant poly(vinyl chloride), a glass fiber-reinforced poly(phenylene ether) or aluminum has been hitherto employed.
[0003] The known flatboat frame has a problem because breakage, cracking or bending is apt to be caused upon collision against, for example, rocks or during transportation in a collapsed state. Especially, pivot or joint portions of the frame pipes, which have a greater tendency to receive stresses, are susceptible to breakage.
[0004] The present invention has been made with the foregoing problem of the conventional flatboat frame in view.
[0005] In accordance with the present invention there is provided a boat comprising a canvas stretched over a knockdown frame, said frame being constructed from fiber-reinforced plastic tubes each containing a synthetic fiber selected from a polyester fiber, a polyamide fiber, a polyethylene fiber, a vinylon fiber and an aramide fiber as a reinforcing fiber.
[0006] In another aspect, the present invention provides a frame for supporting a canvas, characterized in that said frame is constructed from fiber-reinforced plastic tubes each containing a reinforcing, synthetic fiber selected from a polyester fiber, a polyamide fiber, a polyethylene fiber, a vinylon fiber and an aramide fiber and dispersed in a resin matrix, each of said tubes having a specific gravity of 1.5 or less, a bending modulus of elasticity of at least 40 ton/cm², an IZOD impact strength of at least 80 kg.cm and a duPont impact strength of at least 0.2 kg x 500 mm.
[0007] The present invention will now be described in detail below with reference to the accompanying drawing, in which:
Fig. 1 is a partly exploded plan view diagrammatically showing one embodiment of a frame of flatboat according to the present invention;
Fig. 2 is a plan view diagrammatically showing the flatboat of Fig. 1; and
Fig. 3 is a cross-sectional view taken on line III-III of Fig. 2.
[0008] The knockdown frame to be used for the purpose of the present invention is made from a fiber-reinforced plastic tube or pipe in which a synthetic fiber as reinforcing fiber is embedded within a matrix of a plastic material. The synthetic fiber is selected from a polyester fiber, a polyamide fiber, a polyethylene fiber, a vinylon fiber and an aramide fiber. The use of polyamide fibers, vinylon fibers, polyester fibers or aramide fibers is preferred. Vinylon fibers are most preferably used for the purpose of the present invention. The use of glass fibers, metal fibers, ceramic fibers and carbon fibers is disadvantageous and should be avoided.
[0009] The synthetic, reinforcing fibers may be in the form of a cloth, a sleeve, a yarn, or woven or non-woven fabric. The fiber-reinforced plastic tube may be prepared by any known method such as a filament winding method or a sheet winding method. Thus, for example, a prepreg having a resin matrix and reinforcing fibers dispersed in the matrix is wound around a mandrel and the resulting mandrel is heated for the curing of the matrix resin. Alternatively, reinforcing fibers are wound around a mandrel and the wound fibers are impregnated with a resin. The resulting impregnated fibers are then heated for curing the resin.
[0010] The resin to be used as matrix for the reinforcing fibers is preferably a thermosetting resin such as an epoxy resin, a polyester resin or a phenol resin.
[0011] The amount of the reinforcing fibers in the tube is suitably 30-70% by weight based on the total weight of the reinforcing fibers and the matrix resin. When the amount of the reinforcing fibers is less than 30% by weight, the resulting tube may become insufficiently tough and may tend to crack upon being nailed.
[0012] The tube for constructing the frame preferably has a thickness T of 1.0-4.0 mm and an inside diameter D of T/2 to T/0.05, more preferably T/1.0 to T/0.07. The inside diameter D is preferably 5-25 mm. It is preferred that the tube have a specific gravity of 1.5 or less, more preferably 1.0-1.3, a bending modulus of elasticity of at least 40 ton/cm², more preferably 45-200 ton/cm², an IZOD impact strength of at least 80 kg cm, more preferably at least 100 kg.cm and a duPont impact strength of at least 0.2 kg x 500 mm, more preferably at least 0.3 kg x 500 mm.
[0013] In Table 1 below tubes according to the present invention (Sample Tubes Nos. 1 and 2) are compared with known ones (Sample Tubes Nos. 3-5) with respect to physical properties.
Table 1
| Sample No. | 1 | 2 | 3 | 4 | 5 |
| Weight (g/m) | 158 | 148 | 145 | 172 | 160 |
| Bending Modulus of Elasticity (ton/cm²) | 49.6 | 105.9 | 715.6 | 24.4 | 71.4 |
| Bending strength (kgf/cm²) | 12.6 | 17.2 | 10.5 | 11.7 | 7.7 |
| IZOD Impact Strength (kg.cm) | >240 | >240 | 10 | 74 | 64 |
| Condition after IZOD Impact Strength Test | A | A | B | C | C |
| duPont Impact Strength at a height of 500 mm (kg) | 1.0 | 1.0 | 0.3 | 0.3 | 0.3 |
| Condition after duPont Impact Strength Test | A | A | B | C | C |
| Condition after being Nailed | A | A | B | C | C |
[0014] Sample Tube No. 1 had an inside diameter of 13 mm, an outside diameter of 18 mm, a length of 1200 mm and prepared by winding a prepreg, composed of a polyester cloth (weight: 160 g/m²) impregnated with 33% by weight of an epoxy resin, around a mandrel followed by curing and polishing.
[0015] Sample Tube No. 2 had an inside diameter of 13 mm, an outside diameter of 18 mm, a length of 1200 mm and prepared by winding a prepreg, composed of a vinylon cloth (weight: 150 g/m²) impregnated with 33% by weight of an epoxy resin, around a mandrel followed by curing and polishing.
[0016] Sample Tube No. 3 had an inside diameter of 15.6 mm, an outside diameter of 18 mm, a length of 1200 mm and formed of aluminum.
[0017] Sample Tube No. 4 had an inside diameter of 13 mm, an outside diameter of 18 mm, a length of 1200 mm and formed of a heat-resistant polyvinyl chloride.
[0018] Sample Tube No. 5 had an inside diameter of 13 mm, an outside diameter of 18 mm, a length of 1200 mm and formed of a polyphenylene ether reinforced by 30% by weight of a glass fiber.
[0019] In Table 1, the bending modulus of elasticity was measured in accordance with the three point bending method with a span of 300 mm and a cross head speed of 10 mm/min. The IZOD impact strength was measured with an IZOD impact testing machine. The condition of the pipe after the IZOD impact test was evaluated as follows:
A: no change
B: deformed
C: bent
[0020] The duPont impact strength was measured with a duPont impact testing machine by causing a weight block to fall on the sample pipe at a height of 500 mm. The minimum weight of the block which caused deformation or breakage of the sample tube represents the impact strength. The condition of the tube after the impact test was evaluated as follows:
A: no change
B: deformed
C: broken
[0021] The condition of the tube after nailing a nail having a diameter of 2 mm was evaluated as follows:
A: no change
B: deformed
C: broken
[0022] The structure of the framework according to the present invention is not particularly limited. For instance, any conventionally known flatboat framework structure may be suitably used for the purpose of the present invention. One such known flatboat framework is shown in Fig. 1. The framework includes a pair of longitudinally extending, tubular main frames generally designated as 1 and 2. The main frames 1 and 2 are composed of sections 1a-1e and 2a-2e, respectively, which are detachably connected end to end through fitting engagement. Suitable means (not shown) such as springs or pins are provided for tightly holding the main frame in an integral, boat-like structure.
[0023] A pair of laterally extending, front and rear, auxiliary frames 3a and 3b are detachably provided between the main frames 1 and 2. Further, a pair of rectangular-shaped, ring frames 4a and 4b are disposed in the middle of the framework. The ring frames 4a and 4b are detachably connected with each other by connecting pipes 5a and 5b. The ring frames 4a and 4b have vertically extending portions which are detachably linked through suitable brackets (not shown) with the main frames 1 and 2.
[0024] The thus constructed framework is covered with a waterproof canvas 9 as shown in Fig. 2. The canvas 9 has a top opening 12 at a position between the frames 4a and 4b for a rider. As shown in Fig. 3, the canvas 9 has a double-walled structure in the bottom of the boat. Thus, the bottom can be inflated by charging air between upper and lower bottom walls 6 and 7 to provide floatage.
1. A boat comprising a canvas stretched over a knockdown frame, said frame being constructed
from fiber-reinforced plastics tubes each containing a synthetic fiber selected from
a polyester fiber, a polyamide fiber, a polyethylene fiber, a vinylon fiber and an
aramide fiber as a reinforcing fiber.
2. A boat as claimed in Claim 1, wherein each of said tubes has a specific gravity of
1.5 or less, a bending modulus of elasticity of at least 40 ton/cm², an IZOD impact
strength of at least 80 kg.cm and a duPont impact strength of at least 0.2 kg x 500
mm.
3. A boat as claimed in Claim 1 or Claim 2, wherein each of said tubes has a thickness
T of 1.0-4.0 mm and an inside diameter D of T/2 to T/0.05.
4. A boat as claimed in any preceding claim, wherein said reinforcing fiber is a fabric
of a vinylon fiber.
5. A frame for supporting a canvas, characterized in that said frame is constructed from
fiber-reinforced plastic tubes each containing a reinforcing, synthetic fiber selected
from a polyester fiber, a polyamide fiber, a polyethylene fiber, a vinylon fiber and
an aramide fiber and dispersed in a resin matrix, each of said tubes having a specific
gravity of 1.5 or less, a bending modulus of elasticity of at least 40 ton/cm², an
IZOD impact strength of at least 80 kg.cm and a duPont impact strength of at least
0.2 kg x 500 mm.