Technical Field

The present invention relates to a bag enclosed with overtape sealing.

Background

Currently, there are many types of bags or sacks used in applications for transporting and handling products (e.g. bulk solid material, grains or powder). Among them, an open mouth bag is one of the most common bags used in the packaging industry, because the bag has one opening side for conveniently loading the products and low production cost. The open mouth bag has a tubular main body portion formed by woven polypropylene (WPP)-based material with additional liner layer formed by polyethylene (PE), where both opening sides of the bag are enclosed by means of a continuous transverse line of stitches (sewing) in order to prevent leakage of internal products. However, during transportation, the stitched part of the bag may break at needle areas and cause entrance of moisture to the internal products which affects shelf life of the products contained in the bag. Moreover, when tearing the line of stitches to unseal the bag, the scrap threads may contaminate the end-user's production process such as food manufacturing, causing production quality problems.

US7731425B2 disclosed an open mouth bag with overtape sealing for containing products (bulk materials). It is developed to close an open end of the bag without holes and stitching in order to prevent entry of contamination, by providing the open mouth bag formed by woven polypropylene and a folded-over tape (or overtape) capable of sealing. The folded- over tape comprises the woven polypropylene or poly-coated kraft paper as an outer layer and a hot melt adhesive layer as an inner layer of the tape. The inner layer of the tape comes into contact with the outer surface of the bag and is pressed under heat until they are joined firmly together so that the open mouth bag is sealed completely with tape. However, the inner layer of the bag is an adhesive which is different to use of polymer composite for sealing, where the polymer composite is a blend of one or more polymers such as propylene-based elastomer, polyethylene (PE), and polypropylene (PP). US20120308789A1 disclosed a co-extraded multilayer film in packaging applications comprising a polypropylene core layer, a sealant layer, and at least one image-side tie layer, where the sealant layer is a heat sealable material formed by thermoplastic located under the core layer and makes the film readily heat sealable on a substrate by a process of heat sealing. A polymer composite for creating the sealant layer comprises a blend of a first polymer component and a second polymer component. The first polymer component may be a propylene homopolymer, a copolymer or terpolymer of propylene, or combination thereof. The second polymer may include one or more of the polymers such as propylene-based elastomer, low density polyethylene (LDPE), and polypropylene (PP) homopolymer. However, it does not suggest a use of the polymer composite to apply as an inner layer of overtape.

In order to address the aforementioned problem, the present invention provides a bag with overtape for sealing the bag. The overtape comprises an outer layer made of polypropylene (PP), and an inner layer made of polymer composite, where the inner layer has a lower melting point than the outer layer. The inner layer functions as a sealant layer for heat sealing on the bag in order to effectively protect inside products from risk of moisture and entrance of contamination, and therefore provides longer shelf life.

Summary of the Invention

The present invention relates to a bag with overtape sealing for protecting against the risk of moisture and contamination, and therefore provides longer shelf life. The bag (100) with overtape sealing comprises:

- a bag body (102) formed by a bag sheet for containing products, where the bag body (102) comprises a first-opening portion (104) and a second-opening portion (106) located opposite to the first-opening portion (104);

- an overtape (200) provided on the first-opening portion (104) for heat sealing, where the overtape (200) comprises an outer layer (202) and an inner layer

(204); wherein the inner layer (204) has lower melting point than the outer layer (202), where the inner layer (204) formed by a polymer composite comprises a blend of propylene-based elastomer, polyethylene (PE), and polypropylene (PP). Brief Description of the Drawings

For a more complete understanding of the present invention, example of embodiments, and their advantages, reference is made to the following description taken in conjunction with the accompanying drawings, in which like reference numbers indicate like features. The following figures show perspective views of the example embodiments.

Fig. 1 is a block bottom bag with overtape sealing according to the present invention.

Fig. 2 is an overtape on a bag body according to the present invention.

Fig. 3 is a bag having overtape sealing on both opening portions according to the present invention. Fig. 4 is a bag with an overtape having an opening-assisted section applying heat resistant material according to the present invention.

Fig. 5 is a bag with an overtape having an opening-assisted section using a protruding part according to the present invention.

Fig. 6 is a tensile strength comparison of specimens using a tensile testing machine according to the present invention.

Fig. 7 is a test result of the bonding strength comparison according to the present invention.

Fig. 8 is a leak test according to the present invention

Although similar reference numbers may be used to refer to similar elements in the figures for convenience, each of the various example embodiments may be considered to be distinct variations.

Detailed Description

The present invention relates to a bag with overtape sealing for protecting against the risk of moisture and entrance of contamination, and therefore provides longer shelf life. Any aspect shown herein is meant to include its application to other aspects of this invention unless stated otherwise.

Technical terms or scientific terms used herein have definitions as known to an ordinary person skilled in the art unless stated otherwise. Any tools, equipment, methods, or chemicals named herein mean tools, equipment, methods, or chemicals being used commonly by an ordinary person skilled in the art unless expressly stated that they are tools, equipment, methods, or chemicals specific only to this invention.

Use of a singular noun or pronoun with “comprising” in claims or specification means “one” but may also refer to “one or more,” “at least one,” and “one or more than one.”

All components and/or methods disclosed and claims in this application aim to cover embodiments from any action, performance, modification, or adjustment without any experiment that significantly differs from this invention, which would result in creation of an object with the same utility or which would be deemed substantially similar to the present embodiment according to an ordinary person skilled in the art, whether or not such variation is specifically stated in the claims. Therefore, objects that are similar or which may be substitutable for the present embodiment, including those with minor modifications or adjustments that may be clearly devised by an ordinary person skilled in the art should be construed as being within the spirit, scope, and concept of invention as appeared in the appended claims.

Throughout this application, the term “about” means any number referenced herein that could be varied or deviated from any error of equipment, method, or person using said equipment or method.

Example aspects will now be described with reference to the accompanying drawings, which form a part of the present disclosure and which illustrate example embodiments which may be used. As used in the present disclosure and the appended claims, the terms "example embodiment," "exemplary embodiment," and "present embodiment" do not necessarily refer to a single embodiment, although they may, and various example embodiments may be readily combined and/or interchanged without departing from the scope or spirit of example embodiments. Furthermore, the terminology as used in the present disclosure and the appended claims are for the purpose of describing example embodiments only, and is not intended to limit interpretation. In this respect, as used in the present disclosure and the appended claims, the term "in" may include "in" and "on," and the terms "a," "an," and "the" may each refer to the singular and plural. Furthermore, as used in the present disclosure and the appended claims, the term "by" may also mean "from," depending on the context; the term "if may also mean "when" or "upon," depending on the context; and the term "and/or" may refer to and encompass any and all possible combinations of one or more of the associated listed items.

Hereafter, invention embodiments are shown without any purpose to limit any scope of the invention.

In one embodiment of the invention, a bag (100) with overtape sealing comprising:

- a bag body (102) formed by a bag sheet for containing products, where the bag body (102) comprises a first-opening portion (104) and a second-opening portion (106) located opposite to the first-opening portion (104);

- an overtape (200) provided on the first-opening portion (104) for heat sealing, where the overtape (200) comprises an outer layer (202) and an inner layer (204); wherein the inner layer (204) has lower melting point than the outer layer (202), where the inner layer (204) formed by polymer composite comprises a blend of propylene- based elastomer, polyethylene (PE), and polypropylene (PP).

In an exemplary embodiment, the propylene-based elastomer of the inner layer (204) has a melt index when measured at 190 °C in the range of 3.5 to 3.8 g/10 minutes, and a density in the range of 0.86 to 0.89 g/cm ³ .

In another exemplary embodiment, the polyethylene (PE) of the inner layer (204) has a melt index when measured at 190 °C in the range of 4 to 16 g/10 minutes, and a density in the range of 0.91 to 0.93 g/cm ³ .

In another exemplary embodiment, the polypropylene (PP) of the inner layer (204) has a melt index when measured at 230 °C in the range of 20 to 36 g/10 minutes, and a density in the range of 0.88 to 0.92 g/cm ³ .

In another exemplary embodiment, a material of the outer layer (202) can be selected from woven or non-woven of polypropylene (PP), polyethylene (PE), polyethylene terephthalate (PET), and combination thereof.

In another exemplary embodiment, a material of the bag sheet can be selected from kraft paper, woven or non-woven of polypropylene (PP), polyethylene (PE), polyethylene terephthalate (PET), recycled plastic, biodegradable plastic, and combination thereof.

In another exemplary embodiment, the bag sheet further comprises at least one layer of film material selected from a group of polypropylene (PP), polyethylene (PE), polyethylene terephthalate (PET), bi-axially oriented polypropylene (BOPP), cast polypropylene (CPP), cast polypropylene copolymer (CPP COPO) and combination thereof.

In a preferred exemplary embodiment, the film material of the bag sheet is cast polypropylene copolymer (CPP COPO).

In another exemplary embodiment, the overtape (200) further comprises an opening- assisted section (400) for easily unsealing the bag.

In a preferred exemplary embodiment, opening-assisted section (400) comprises a heat resistant material (402) provided between the overtape (200) and the bag body (102).

In another preferred exemplary embodiment, opening-assisted section (400) comprises a protruding part (404) protruded from the overtape (200).

In another exemplary embodiment, the overtape (200) is sealed in such a way that the area of heat sealing is lower than the top edge of the first-opening portion (104) in the range of 1 to 5 mm.

Example Embodiments

These example embodiments will now be described below with reference to the accompanying drawings, which form a part of the present disclosure.

Fig. 1 shows an example of a bag (100) having block bottom shape and sealing with an overtape (200) for containing and transporting products. The bag (100) has a bag body (102) formed by a bag sheet, where the bag sheet is rolled up to secure one end of the bag sheet to the opposite end of the bag sheet and then applying heat. The bag body (102) is tubular in shape and has a first-opening portion (104) at the top for containing the products, while a second- opening portion (106) opposite the first-opening portion (104) is secured as block bottom

(108).

A material of the bag sheet may be selected from a kraft paper, woven or non-woven of polypropylene (PP), polyethylene (PE), polyethylene terephthalate (PET), and combination thereof. The bag sheet may be reinforced for tearing protection by coating with film material to be an outer surface of the bag sheet. The film material may be selected from polypropylene (PP), polyethylene (PE), polyethylene terephthalate (PET), bi-axially oriented polypropylene (BOPP), cast polypropylene (CPP), cast polypropylene copolymer (CPP COPO) and combination thereof. Moreover, the use of overtape (200) replaces a use of stitches (sewing), this allows the overtape (200) to be folded over the opening portion of the bag (100) and provides a higher tensile strength, because there is no sewing line pattern that destroys the structure of the bag body. Therefore such characteristics causes the bag (100) itself to able to use less strong materials to form the bag and save costs, where the less strong materials may be selected from recycled plastic or biodegradable plastic in order to reduce single-use plastic that is extremely harmful to the environment.

The bag (100) is used to contain the products of bulk material such as seeds, cement, mortar, chemicals, animal feeds, fertilizer, and combinations thereof. After fully containing the products, the bag (100) is taken through the sealing process, where the first-opening portion (104) is secured using the overtape (200). The overtape (200) comprises an outer layer (202) and an inner layer (204) as shown in Fig. 2, wherein the inner layer (204) has lower melting point than the outer layer (202). In the sealing process, the overtape (200) is half folded along the longitudinal line to cover the first-opening portion (104) at the top of the bag body (102), where some portion of overtape (200) extends beyond the lateral side edges of the bag body (102) for increasing a sealing area. Then, the heat sealing is processed using a pressing machine to press hot rollers or heaters on the overtape (200), and applying heat at temperature in range of 130 to 150 degree Celsius causing heat conduction through the inner layer (204), where the area of heat sealing is lower than the top edge of the first-opening portion (104) in the range of 1 to 5 mm. The overtape (200) is continuously heated until the inner layer (204) is melted and bonded to the outer surface of the bag body (102). Therefore, the first-opening portion (104) of the bag (100) is sealed completely with overtape (200). If the area of heat sealing is less than 1 mm lower than the top edge of the first-opening portion (104), the obtained bag (100) is prone to be less strong due to the overheating at the folded edge of the overtape (200). On the other hand, if the area of heat sealing is more than 5 mm lower than the top edge of the first-opening portion (104), the obtained bag (100) is less resistant to moisture.

A material of the outer layer (202) may be selected from woven or non-woven polypropylene (PP), polyethylene (PE), polyethylene terephthalate (PET), and combination thereof, preferably polypropylene (PP). The outer layer (202) may be formed by one material or multilayers of materials, or laminated with PP, PET, CPP COPO or BOPP film to protect shrinkage, and it is not limited that each layer of material be made of the same polymer. The inner layer (204) is polymer composite having lower melting point than the outer layer (202), where the inner layer (204) comprises a blend of propylene-based elastomer, polyethylene (PE), and polypropylene (PP). The propylene-based elastomer of the inner layer (204) has a melt index when measured at 190 °C in the range of 3.5 to 3.8 g/10 minutes, and a density in the range of 0.86 to 0.89 g/cm ³ . The polyethylene (PE) of the inner layer (204) has a melt index when measured at 190 °C in the range of 4 to 16 g/10 minutes, and a density in the range of 0.91 to 0.93 g/cm ³ . The polypropylene (PP) of the inner layer (204) has a melt index when measured at 230 °C in the range of 20 to 36 g/10 minutes, and a density in the range of 0.88 to 0.92 g/cm ³ .

Fig. 3 shows an example of a bag (100) using an overtape (200) for sealing on both opening portions according to one embodiment of the present invention. The bag (100) has a bag body (102) including a first-opening portion (104) at the top and a second-opening portion (106) at the bottom. Before putting products into the bag (100), it must use the overtape (200) to secure the second-opening portion (106), where the sealing process is the same as aforementioned. The first-opening portion (104) is used to enter products, and then secure the first-opening portion (104) with the overtape (200). Hence a characteristic of using overtape sealing can protect against the risk of moisture and contamination entering into both opening portions (104, 106) completely.

Fig. 4 shows an example of the bag (100) with an overtape (200) having an opening- assisted section (400) for easily unsealing the bag. The opening-assisted section (400) comprises a heat resistant material (402) provided between the overtape (200) and the bag body (102). The heat resistant material (402) forms itself as a heat-resistant layer to prevent the thermal conduction such that an area having heat resistant material (402) applied is less effectively sealed between the bag body (102) and the overtape (200). As a result, the overtape (200) can be easily pulled off at the heat resistant position to uncover the overtape (200). The heat resistant material (402) includes heat resistant ink commercially available in the market. Examples of heat resistant material (402) include isopropyl alcohol based materials, or ink substance having high thermal resistance. The heat resistant material (402) can be applied either on the bag body (102) or the overtape (200) by means of, for example, spray, airbrushing, coating, painting, printing and likes. The heat resistant material may be applied in a pattern between the bag body (102) and the inner layer (204) of overtape (200).

Fig. 5, shows another example of the opening-assisted section (400). The opening- assisted section (400) can be formed by partial application of heat to overtape, where non-heat applied section will create a protruding part (404) protruded from the overtape (200). Since the protruding part (404) is not be sealed to the bag body (102), the protruding part (404) can function as a pull-tab to uncover the overtape (200). Moreover, the protruding part (404) may be made from either the same material as the bag body (102) or different materials from the bag body (102). Furthermore, size of the protruding part (404) can be adjusted, as long as the protruding part (404) can be used to unseal the bag.

Testing of the bag according to the present invention

Testing of the bag with overtape sealing according to the present invention, which was named as Sample A, Sample B, Sample C, Sample D, was done comparing conventional bags, which were named as Comparative Sample 1, 2, and 3, using stitching technique for enclosing the bag. Detailed characteristics of each sample are shown in Table 1 and Table 2. To perform the tensile test, four samples (Sample A, and Comparative Sample 1-3) were tested by a tensile testing machine (Tinius Olsen H5KT) using a tensile testing standard of TIS. 729-2553. The tensile strength of each sample is shown in Fig. 6. It was found that Sample A had approximately 40% higher tensile strength than Comparative Sample 3, and 23% higher tensile strength than the Comparative Sample 2, and almost 3 times higher tensile strength than Comparative Sample 1. It was demonstrated that the bag according to the present invention (Sample A) had highest strength, because the overtape did not destroy the fabric structure of the bag body in the sealing process, while the sewing pattern of stitching in Comparative Sample 1, 2, and 3 destroyed the fabric structure of the bag body, so the line of stitching area was weak and less resistant to tensile force.

Table 1 shows detailed characters of the sample bags with stitching technique

Table 2 shows detailed characters of the sample bags with overtape sealing Since Sample A and Sample D were made of lightweight material with different coating film, they were selected to study the bonding strength between the overtape and the material of film layer. Sample A was lightweight woven PP coated with cast polypropylene copolymer (CPP COPO) film, while Sample D was lightweight woven PP coated with bi-axially oriented polypropylene (BOPP) film. To perform the bonding strength test, two samples were tested by digital force gauge under standard Technique A of ASTM F88. The test result is shown in Fig. 7. It was found that Sample A had approximate bonding strength of 22.83 N/inch which is 4 times higher than Sample D. This shows that using CPP COPO film as coating material on the bag body provides higher performance than use of BOPP film.

Sample A, Sample B, Sample C, Sample D and Comparative Sample 2 were selected to study a drop test. The drop test was performed by providing 5 bags of Sample A, 5 bags of Sample B, 5 bags of Sample C, 5 bags of Sample D and 5 bags of Comparative Sample 2 respectively, and filling each bag with 50 kg of fertilizer. Each bag of sample was subject to the drop test at a height level of 1.2 meters for 10 times (5 times on the front and 5 times on the back). After that, the bags which passed the drop test at height of 1.2 meters were subject the drop test at higher levels until the height of 3.1 meters. Results of the drop test of Sample A to D, and Comparative Sample 2 are shown in Table 3 to 7. It was found that all bags of Sample A passed the drop test. For Sample B, 4 of 5 bags did not pass the test at 3.1 meters. For Sample C, none of the bags passed the test at 3.1 meters. For Sample D, 2 of 5 bags did not pass the test at 1.45 meters, while none of the bags passed the test at 2.05 meters. However, for Comparative Sample 2, 2 out of 5 bags did not pass the test at 1.2 meters. 2 of 3 bags of Comparative Sample 2 did not pass the test at 1.45 meters, while none of the bags passed the test at 3.1 meters. Therefore, the bag with overtape sealing according to the present invention was found to be stronger than conventional sewn bags.

When comparing the bag with overtape sealing of Sample A to D, they were formed by different material which had an impact on performance in the drop test result. The results showed that the bag coated with CPP COPO film was stronger than the bag coated with BOPP film. However, when considering the fabric weight, it was found that the higher fabric weight the more easily the bag would break according to the drop test performance. From the test result, it suggested that when using the overtape to seal the bag, the bag should be a lightweight material, so as to facilitate a heat transfer efficient for completely bonding the inner layer of overtape on the bag. Table 3 shows drop test results of Sample A

Table 4 shows drop test results of Sample B

Table 5 shows drop test results of Sample C Table 6 shows drop test results of Sample D

Table 7 shows drop test results of Comparative Sample 2

In addition, Sample A was selected to study a moisture test compared with a sewn bag having HOPE liner (which were named as Comparative Sample 4). The moisture test was performed by providing 5 bags of Sample A and 5 bags of Comparative Sample 4 respectively, and filling each bag with 20 kg of fertilizer. Then, each bag was left in standard atmosphere for approximately 6 months. After that, each bag was opened and the moisture content of the fertilizer inside the bags was investigated using a moisture analyzer. Results of the moisture test of Sample A and Comparative Sample 4 are shown in Table 8. It was found that Sample A showed 0.11% of moisture content while Comparative Sample 4 showed 0.11% of moisture content. The result implied that the bag with overtape sealing according to the present invention did not need a layer of HOPE liner inside the bag to prevent moisture. Thus, the bag with overtape sealing according to the present invention could prevent moisture in the similar level to the sewn bag having HOPE liner.

Table 8 show results of the moisture test of Sample A and Comparative Sample 4

To further investigate a bag strength having the overtape according to this invention, after drop testing was completed, Sample Ato D that passed the drop test at highest achievable level were selected for a leak test to determine if any leak of liquid flows through the overtape. The leak test was performed by using a penetrant testing material consisting of a solvent and red dye, then sprayed inside the bag body at the edge of overtape sealing and the leakage observed, as shown in Fig. 8. Results of the leak test of Sample A to D are shown in Table 9. It was found that Samples A to C having overtape sealing could prevent the leakage of penetrant testing material and passed the leak test well, and there was no leak of the penetrant testing material outside the bag. Even if Sample D had the overtape sealing and passed the drop test at 1.45 meters, it did not pass the leak test because the bag coated with BOPP film was less strong and after dropping it increased the chance of leakage. Table 9 show results of the leak test of Sample A to D

While an embodiment of the invention has been illustrated and described, it is appreciated that various changes can be made therein without departing from the spirit and scope of the invention. While various embodiments in accordance with the disclosed principles have been described above, it should be understood that they have been presented by way of example only, and are not limiting. Thus, the breadth and scope of the example embodiments described in the present disclosure should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the claims and their equivalents issuing from this disclosure. Furthermore, the above advantages and features provided in the described embodiments shall not limit the application of such issued claims to processes and structures accomplishing any or all of the above advantages.

Best Mode or Preferred Embodiment of the Invention

Best mode or preferred embodiment of the invention is as provided in the description of the invention.