Patent Publication Number: US-2010117262-A1

Title: Method of dual molding products with logos and other indicia

Description:
FIELD OF INVENTION  
     This present application relates to a method of incorporating indicia on a wide variety of products. More specifically, the invention involves a method of dual molding a permanent stamp or logo into a soft overmolded, hard core product. Even more particularly, the inventive method involves selectively positioning logos or indicia on products formed by dual molding without requiring fabrication of additional molds when different logos or indicia are incorporated. 
     BACKGROUND OF THE INVENTION  
     A wide variety of consumer and industrial products are created through the process of injection molding. To produce such products, at least one mold is created from steel or other suitable metal or alloy that is capable of withstanding the temperature and pressure that accompanies the injection molding process. Traditionally, the mold is formed from two sections and is designed to receive a liquefied thermoplastic elastomer or other suitable plastic or material that is injected into the mold. The shape of the item that that is formed from the injection molding process is the inverse or negative of the interior surface of the mold that is exposed to the liquefied thermoplastic material. 
     One major problem with injection molding is the relatively high cost for creating a mold. The concern over high production costs for the creation of a mold is further magnified when a manufacturer molds the same product (or very similar product) for a number of different customers but each customer requires the incorporation its own logo and/or other indicia onto the surface of its own version of the product. In this case, because of the substantial differences in the logo or indicia, a separate mold (or at least a separate section of a mold) must be fabricated to produce each customer&#39;s individualized product. This is the case even though the product that is produced on behalf of one customer may otherwise be the same as (or very similar to) that produced with a different logo or indicia on behalf of one or more other customers. This situation may likewise occur where a single customer uses a number of different brand names or logos on the same type of product. 
     The deficiency in the process discussed above is clearly demonstrated in the context of U.S. Pat. No. 6,726,868, which is entitled Double Molding Process Whereby A Sign is Produced On A Product While Said Product Is Molded. In particular, U.S. Pat. No. 6,726,868 discusses a double molding process where visual information, such as a logo, name, trademark or symbol, is produced on a product while the product is being molded. The process involves the production of an inner core formed of a first molding material, where the core incorporates a cavity in the shape of the visual information or sign that is to be produced. The process also involves the molding of an outer cover formed of a second molding material onto the inner core. When the outer cover is molded, the material forming the outer cover fills the cavity producing the visual information on the product. The process of forming the inner core with a cavity that corresponds to the visual information necessarily requires the use of a mold that contains complementary projections to form the cavity in the inner core that corresponds to the visual information. Significantly, each time the visual information is modified, even though the product itself may not otherwise change (or change significantly), a different mold needs to be fabricated to produce the product. 
     The problem of having to create a different mold for a particular product when a different logo or indicia is incorporated into the same (or substantially similar) product is further experienced when a company wishes to produce the same dual injection molded product under three distinct brand-names. For example, in the case of a putty knife that is produced under distinct brand names, the blade and handle of each of brand of knife is the same (or nearly identical), but the logo different in each. The handle of all three is constructed utilizing the same dual molding process, where the inner core comprises a hard plastic and also forms an exposed logo or indicia, and the outer cover comprises a thermoplastic elastomer, such as Santoprene®, which forms a soft handle that covers all or a significant part of the inner core except for where the logo or indicia is exposed. In this situation, even though the handles are essentially the same, since the logo for each is different, three different molds are typically created in order to construct the handle. While the costs for creating three molds for a product can potentially be absorbed, the problem becomes significantly amplified when there are tens or hundreds of products to produce under multiple brand names that each requires a unique mold. 
     To overcome the issues discussed above, companies often resort to silk-screening, hot-stamping or pad printing logos on a product. However, this has proven to be an ineffective solution. While the quality of inks have improved over the years, they usually fade over time, particularly if the product is a handle, is handled regularly or is subject to repeated contact. Moreover, if the product has a soft surface, such as one made of Santoprene®, the imprint can be lost relatively quickly. 
     SUMMARY OF THE INVENTION  
     In view of the deficiencies and drawbacks in the prior art, it is a primary object of the present invention to provide an improved method of dual injection molding that reduces the number of molds needed to produce products that incorporate different logos and/or other indicia but which are otherwise identical or substantially the same. 
     Another primary object of the present invention is to provide a method of producing dual injection molded products that is more efficient and provides cost savings to manufacturers. 
     Yet another object of the present invention is to overcome issues associated with silk-screening, hot-stamping or pad-printing a logo or other indicia on a product by providing a permanent insert that is molded (or otherwise created) from a hard plastic (such as polypropylene), soft elastomer (such as Santoprene®) or other suitable material. 
     Additional objectives will be apparent from the description of the invention that follows. 
     In summary, there is provided in a preferred embodiment of the present invention an improved method of injection molding that reduces the need to fabricate additional molds in order to create injection molded products having a logo and/or other visual indicia, and which also overcomes the problems associated with applying inks or other non-permanent indicia on a product. Generally, the method comprises the following steps: 
     a. providing a first mold to produce an inner portion or core of a product; 
     b. forming the inner portion or core from a first plastic material; 
     c. providing an insert in the form of a logo or other indicia; 
     d. attaching, engaging and/or combining the insert to the inner portion or core of the product; 
     e. providing a second mold to receive the core and insert combination; and 
     f. injecting a second plastic material into the second mold around the core-insert combination, thereby forming a cover around the core and leaving at least one surface of the insert exposed so that it is visible. 
     It should be understood that one or more steps may be added to those listed above, and that any one or more of the particular steps above may be removed or substituted by one or more other steps when appropriate, while still keeping within the spirit and scope of the present invention. 
     In a preferred embodiment of the present invention, the first plastic material used to form the core is a hard plastic, such as polypropylene. Also, in a preferred embodiment of the present invention, the second plastic material used to form the cover is a thermoplastic elastomer, such as Santoprene®. 
     By utilizing an insert that is constructed separate from and then combined with the inner portion of a product, the product can be manufactured under a host of different brand names by simply using different logo or indicia inserts with a particular inner portion. Through this method, a product can be manufactured with a different appearance without having to use a different mold (or series of molds) to create the product. 
     Generally, an insert is created quite inexpensively when it is molded, since a mold for producing the insert is quite small and of a fast cycle. During overmolding of the insert and core combination, the overmolding material, typically Santoprene®, is allowed to flow around closed parts of the insert via one or more channels. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       With reference to the attached drawings: 
         FIG. 1  is a female mold section of a mold utilized in connection with the injection molding of an inner portion or core of a tool handle; 
         FIG. 2  is a cross section of a mold utilized in connection with the injection molding of the inner portion of a tool handle, the mold comprising one female mold section and one male mold section; 
         FIG. 3  is an inner portion of a tool handle created by an injection molding process utilizing the mold shown in  FIG. 2 ; 
         FIG. 4  is a bottom, rear and left perspective view of a logo insert utilized in connection with the present invention; 
         FIG. 5  is a top view of the logo insert shown in  FIG. 4 ; 
         FIG. 6  is a female mold section of a mold utilized in connection with the injection molding of a soft cover of a tool handle; 
         FIG. 7  is a cross section of a mold utilized in connection with the injection molding of the soft cover of a tool handle, the mold comprising one female mold section and one male mold section; 
         FIG. 8  is a partial cross section of the mold depicted in  FIG. 7 , showing the flow of a thermoplastic elastomer within the mold used to form the soft cover of a tool handle; 
         FIG. 9  is a tool handle with a logo and soft cover exterior formed utilizing the mold shown in  FIG. 7 ; and 
         FIG. 10  is a partial cross section taken along line  10 - 10  of  FIG. 9 , showing the thermoplastic elastomer surrounding the logo insert. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
     With reference to  FIGS. 1 through 10 , there is shown and described a method for injection molding products having logos or other indicia. The method comprises providing a first mold, mold set or die  10 , a cross section of which is shown in  FIG. 2 . The first mold  10  has a female mold section  11  shown in  FIG. 1  which has four apertures  14  at the corners thereof to receive correspondingly positioned cylinders or projections  16  of a complementary male mold section  12 . It should be understood that each of the apertures  14  of the female mold section  11  and each of the correspondingly positioned projections  16  of the male mold section  12  are generally interchangeable with one another. 
     The female mold section  11  has two small wells or cavities  18 ,  20 . In the context of the injection molding process used to create the particular tool handle  140  shown in  FIG. 9 , the male section  12  also has two small cavities, each of which has dimensions and features similar to those of cavities  18 ,  20 . Although mold sections  11 ,  12  have dimensions and features that are similar to one another, it should be understood that the process described herein may also be utilized to create products with logos or other indicia using mold sections that vary from one another. When mold sections  11 ,  12  are joined, they form larger cavities  19 ,  21  as shown in  FIG. 2 . These larger cavities  19 ,  21  yield the contours, overall shape and other features of the inner portion or core  40 , as shown in  FIG. 3 . 
     The female mold section  11  has an inlet  22  for receiving polypropylene or other suitable hard plastic (in liquefied form) into the mold  10 . From the inlet  22 , the polypropylene travels through a sprue  24 , which is the arrow-shaped passage through which the liquid material travels to the mold  10  where it solidifies to form the core  40 . Just before entering the cavities  19 ,  21 , the liquid material passes through a gate  26 . The location of the gate  26  is often seen as a small nub or projection called a “gate mark” on the outside edge of the piece that is molded. Optionally, a runner or larger channel may be provided as well. When a runner is incorporated, a sprue is provided as a smaller channel that diverts from the runner to the individual part(s) that are molded. 
     The cavities  18 ,  20  of the female mold section  11  each have a projection  28 ,  29  that preferably extends along the length of each cavity  18 ,  20 , respectively. The projections  28 ,  29  form a relatively thin ridge that is preferably about two inches in length. The dimensions (i.e., length, width and height) of the projections  28 ,  29  can be modified as needed. Further, the cavities of the male mold section  12  have projections  30 ,  31  with features and dimensions identical to those of projections  28 ,  29 , but which can be modified or entirely eliminated as desired. The purpose of each of the projections  28 ,  29 ,  30 ,  31  is to form a corresponding receiving slot or pocket  42  in the inner portion or core  40 , as shown in  FIG. 3 . 
     The receiving slot  42  on the surface  44  of the core  40  receives a logo insert  50  or insert that incorporates other visual indicia. One example of a logo insert  50  is shown in  FIGS. 4 and 5 , namely the trademark “Allway.” In a preferred embodiment, the logo insert  50  includes a logo portion  52  and a rail or ledge  54  that fits into receiving slot  42 . In order for the rail  54  to rest properly and snugly in the receiving slot  42 , each of the projections  28 ,  29 ,  30 ,  31  is formed with suitable dimensions such that the receiving slot  42  that is formed in the core  40  is large enough to receive the rail  54  of the logo insert  50 . Preferably, the rail  54  fits snugly into the receiving slot  42  so that logo insert  50  is not easily dislodged. It should also be understood that other conventional means to connect an insert to a core can be employed besides the slot  42  and rail  54  combination. Furthermore, in order to accommodate a wide variety of logo and indicia inserts without having to fabricate an entirely new mold or mold section, it is desirable that the length of the receiving slot be long enough to accommodate approximately 1-20 alphanumeric characters. In addition to including traditional letters and numbers, it should be understood that an alphanumeric character may also comprise symbols which are not traditional letters or numbers. Of course, the length of the slot can be modified as needed depending on the products being manufactured. 
     The female mold section  11  preferably includes a series of traversing ridges or projections  36 . In a preferred embodiment, the projections  36  are generally perpendicular to projections  28 ,  29 . Traversing projections  36  in the female mold section result in a number of short channels  46  on the surface  44  of the core  40 . Traversing projections  37  are also provided on the male mold section  12  to create a series of short channels on the opposite side of the core  40  as well. 
     The female mold section  11  also provides spaces  38  within which a mock blade or blade substitute is inserted. The insertion of a mock blade in the mold  10  creates a corresponding opening  48  at the front of the core  40  to receive a blade or other working tool end. Spaces  39  are also provided within which a metallic hammer end  49  can be inserted and provided as part of the core  40 . 
     After the core  40  is formed, a logo insert  50  is positioned in the receiving slot  42  so that the insert  50  is attached to, engaged or combined with the core  40 . The core-insert combination is then placed in a second mold, mold set or die  110 . The second mold  110  has a female mold section  111  shown in  FIG. 6  which has four apertures  114  at the corners thereof to receive correspondingly positioned cylinders or projections  116  of a complementary male mold section  112 . It should be understood that each of the apertures  114  of the female mold section  111  and each of the correspondingly positioned projections  116  of the male mold section  112  are generally interchangeable with one another. 
     The female mold section  111  has two small wells or cavities  118 ,  120  that each receives a single core  40 . In this instance, each core  40  comprises two logo inserts  50 , but it should be understood that more or less inserts may be utilized. In the context of the injection molding process used to create the particular tool handle  140  shown in  FIG. 9 , the male section  112  also has two small cavities, each of which has dimensions and features similar to those of cavities  118 ,  120 . Although mold sections  111 ,  112  have dimensions and features that are similar to one another, it should be understood that the process described herein may also be utilized to create products with logos or other indicia using mold sections that vary from one another. When mold sections  111 ,  112  are joined, they form larger cavities  119 ,  121  as shown in  FIG. 7 . These larger cavities  119 ,  121  yield the contours, overall shape and other features of the finished handle  140 , as shown in  FIG. 9 . 
     The female mold section  111  has an inlet  122  for receiving Santoprene® or other suitable thermoplastic elastomer (in liquefied form) into the mold  110  around the core  40  and logo insert  50 . From the inlet  122 , the Santoprene® travels through a sprue  124  through which the liquefied Santoprene® travels to the mold  110  where it solidifies to form a soft exterior cover  130 . Just before entering the cavities  119 ,  121 , the liquid Santoprene® passes through a gate  126 . Optionally, a runner or larger channel may be provided as well. When a runner is incorporated, a sprue is provided as a smaller channel that diverts from the runner to the individual part(s) that are molded. 
     The path of the flowing thermoplastic elastomer within the mold  110  used to form the soft cover  130  is shown in  FIG. 8 . The elastomer enters the mold  110  at the gate  126  and flows around the core  40 . As a result of the channels  46  which are incorporated into the surface  44  of the core  40 , the elastomer is able to proceed between the surface  44  of the core  40  and the logo portion  52  of the logo insert  50 . The channels allow the flowing elastomer to reach the closed spaces of an alphanumeric character, symbol, logo or the like as shown in  FIGS. 8 and 10 . For example, alphanumeric characters which incorporate closed spaces include the letters A, B, D, O, P, Q and R, and the numbers 0, 4, 8 and 9. By entering the closed space from beneath the logo portion  52 , the elastomeric material fills in each available space of the insert  50 . 
     As an alternative to or in conjunction with providing channels  46  on the surface  44  of the core  40 , the logo insert  50  may be elevated or raised relative to the surface  44  of the core. Elevating the insert  50  serves a similar function as that afforded by the channels  46 , allowing the elastomeric material to flow beneath logo portion  52  of the insert  50  into closed spaces. Elevating the insert  50  may be accomplished by forming a receiving slot  42  that is more shallow than the height of the rail  54  of the logo insert  50 . 
     After cooling of the thermoplastic elastomer, a soft cover  130  is formed around the core  40  and logo insert  50  as shown in  FIG. 9 , leaving the exterior surface  56  of the logo portion  52  visually exposed. Preferably, the exterior surface  56  is flush with the surrounding cover  130 . It should also be appreciated that the thickness of the cover can be adjusted as desired by adjusting the size of the mold cavities and/or by adjusting the diameter or thickness of the core. Thus, for example, assuming the size of the core is kept constant, a larger mold cavity yields a thicker exterior cover. 
     Using the dual injection molding process described above, one pair of molds can be used to create a given product with a variety of logos or other visual indicia. For example, when one tool is manufactured under four different brand names by employing a dual injection molding process, only one pair of molds is required instead of four pairs of molds. 
     Even taking into account a separate mold that may be used to create the logo insert itself, the cost savings are still significant, particularly when many different products using many different brand names are manufactured. For example, if four different products having four different logos are created, up to 32 different molds would need to be fabricated using conventional methods of manufacture: 16 molds for each of the 16 different cores, and then up to 16 molds to create the soft cover exterior. If the soft cover exterior molds can be re-used regardless of the logo that is incorporated, then only 4 need to be fabricated, but if not, up to 16 would need to be fabricated. In contrast, using the inventive process described herein, only 12 molds need to be fabricated: 4 molds for the logo inserts, 4 molds to create each of the cores, and 4 molds to create the soft cover exterior. The savings on mold fabrication is alone is evident, and is even more significant when there are a larger number of products and logos to be created. 
     It should be understood that a logo insert can be constructed out the same or different material than the material used to form a core. For example, instead of polypropylene or other hard plastic, any suitable metal or soft Santoprene® can be used. When molding a logo insert, a separate mold or die (which is similar in many basic respects to the mold  10  used to create the core  40 ) is provided to receive the polypropylene or other hard plastic in the shape of the logo insert. It should further be understood that when utilizing both an insert and cover that are formed of the same thermoplastic elastomer such as the soft Santoprene® it is preferable to utilize different colored materials so that there is a contrast between the insert and cover. 
     It should be understood that the process described herein can be applied to the manufacture of a host of different products, not just tool handles as exemplified in a preferred embodiment of the invention. In particular, the process can be applied to any product that incorporates an embedded logo or indicia and which is dual injection molded, having a hard plastic core covered with a soft thermoplastic exterior. 
     Although the invention is described in terms of particular embodiments, it is to be understood that the embodiments are merely illustrative of an application of the principles of the invention. In particular, while the invention is described primarily in terms of a method of dual injection molding of a tool handle featuring visual material, it should be understood that a number of other products can be constructed using the process described herein. It should also be appreciated that numerous modifications may be made and other arrangements may be devised while still keeping within the spirit and scope of the invention.