1. Field of the Invention
The present invention relates generally to a method of making foaming members, and more particularly to a method of making a foaming member with heterogeneous foaming layers.
2. Description of the Related Art
Conventional methods of making a rubber foaming member, natural robber or artificial rubber, are classified into two categories, hot pressing and continuous extrusion. Hot pressing method includes the step of pressing a die with rubber material therein for heating and pressing to make the rubber foaming member. Continuous extrusion includes the step of extruding the rubber material by an extruder and rolling it to form a continuous rubber film, and then the rubber film is sent to a box for vulcanization to form a foaming member.
For a requirement of a variety of products, the rubber foaming member of single material is out of the market. Some rubber foaming members are attached with a skin layer of heterogeneous material to provide a fancy look, extra functions, or other purposes that consumers may have greater willing to buy them. For the technique of rubber foaming member attached with skin layer, a conventional method includes the steps of coating adhesive on the rubber material to attach the skin layer thereon, and then the stack is sent for vulcanization.
Aforesaid method is incorporated with adhesive that may cause air or water pollution.
The primary objective of the present invention is to provide a method of making a foaming member with heterogeneous foaming layers, which has no adhesive to attach the layers together.
According to the objective of the present invention, a method of making a foaming member with heterogeneous foaming layers includes the steps of: adding a foaming agent and an accelerator to a first material, which is a flexible material, and a second material, which is a non-flexible material, respectively, and then pressing and stirring the first material and the second material respectively for well mix; pressing the first material and the second material respectively to form a first material piece and a second material piece; stacking the first material piece and the second material piece to form a stack; vulcanizing the stack in a high pressure and high temperature environment to bond the first material piece and the second material piece together firmly; and releasing pressure on the stack to get a foaming member.
The present invention further provides another method including the steps of: adding a foaming agent and an accelerator to a first material, which is a flexible material, and a second material, which is a non-flexible material, respectively, and then pressing and stirring the first material and the second material respectively for well mix; pressing the first material and the second material respectively to form a first material piece and a second material piece; stacking the first material piece and the second material piece to form a stack; vulcanizing the stack in a high pressure and high temperature environment to bond the first material piece and the second material piece together firmly; and releasing pressure on the stack to get a foaming member.
As shown in
The first step 100 is stirring. A first material and a second material are added with foaming agent and accelerator respectively, and then the first and second materials are stirred and pressed repeatedly in stirring machine respectively. Next, the first and second materials are sent to mixing machine for another mixing process.
In the present invention, the first material is a flexible foaming material, such as thermoplastic rubber (TPR), and the second material is a non-flexible foaming material, such as polyethylene (PE). The foaming agent is an organic foaming agent, such as azobisformamide (ADCA), and the accelerator is a rubber vulcanization accelerator, such as TMTD and MBT. The first and second materials are added with sulfur donor agent (such as sulfur) and fillet (such as reinforcing agent) and other agent for reduction cost and improvement the physical properties (such as rubber grade carbon black, fumed silica, calcium silicate (CaSiO3), and calcium carbonate (CaCO3) respectively. The first and second materials may be added with different colors.
The second step 110 is pressing the first and second materials into piece-like members by specific machine.
The third step 120 is stacking the first material pieces 12 and second material pieces 14 alternately and adding a bonding medium 16 therebetween to form a stack.
The bonding medium 16 may be a thermoplastic elastomer (TPE). The thermoplastic elastomer includes different flexible plastics of a series. In the present invention, the bonding medium 16 is styrenic block copolymer (SBC), which includes a constituent that may bond to the first and second materials 12, 14 respectively. The bonding medium 16 may be added with color as same as the first or second materials 12, 14.
The fourth step 130 is vulcanization in a high temperature and high pressure environment. The stack, with the first material pieces 12, the second material pieces 14 and the bonding medium 16, is put in a die for vulcanization in a high temperature and high pressure environment that the bonding medium 16 may bond the first material pieces 12 and the second material pieces 14 together firmly.
The fifth step 140 is release of pressure and opening the die in a predetermined time that a foaming member 10 with different foaming layers (the first and second materials 12, 14) will be formed, as shown in
The machines and devices used in aforesaid steps are the common tools used in the process of making the foaming member, and they are not involved in the main characters of the present invention, so we won't describe their detail here.
Therefore, the present invention uses the gas pressure generated in the chemical reaction of vulcanization to bond the heterogeneous first and second material 12, 14 together that no adhesive is added in the present invention to cause pollution.
In the present invention, the first material 12 may be a flexible material, and the second material 14 may be a soft and skid proof material that the foaming member 10 made by the method of the present invention may have all functions of soft, support, cushion, shock absorption, and skid proof, such a foaming member is preferred for sport pad, sole of shoes and the like.
The second step 210 is pressing first and second materials into piece-like members by specific machine.
The third step 220 is softening. A softener is coated on the first material and the second material, and then the first material and the second material are heated to 150° C. to 250° C. for softening the first material and the second material. The softener is a common agent using in the process of making rubber products. The softening step 220 may be replaced by exposing the first material and the second material under infrared rays to soften the surfaces thereof.
The fourth step 230 is stacking the first material pieces and the second material pieces alternately to form a stack.
The fifth step 240 is pressing the stack by a rolling device.
The sixth step 250 is vulcanization. The stack, with the first material pieces and the second material pieces, is put in a die for vulcanization in a high temperature and high pressure environment that the first material pieces 12 and the second material pieces 14 are bonded together firmly to form a foaming member.
The last step is cooling the foaming member to room temperature and rolling it on a reel.
In conclusion, the method of the present invention may make a foaming member with heterogeneous foaming layers and no adhesive is added in the process that will not cause pollution.
The description above is a few preferred embodiments of the present invention and the equivalence of the present invention is still in the scope of the claim of the present invention.
Number | Date | Country | Kind |
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96125686 | Jul 2007 | TW | national |