M-bottom paper bag and manufacturing process thereof

Abstract

The invention relates to the technical field of paper bag processing, and discloses an M-bottom paper bag and a manufacturing process thereof. The paper bag comprises two front surfaces, two side surfaces and a bottom surface, wherein the bottom surface comprises a first bottom surface and a second bottom surface which are connected into a whole. A folding mark vertically extending to the second bottom face is arranged in the middle of the side face, a first inclined folding mark obliquely extending downwards from the folding mark to the bottom corner and a second inclined folding mark obliquely extending from the bottom corner to the first bottom face are arranged below the side face, and a folding part is formed on the inner side of the second inclined folding mark. During folding, the folding parts are inwards folded towards the bottom of the paper bag along with the second bottom surface to seal the bottom corners; the second bottom surface is folded along the folding mark to drive the side surface to form an M-bottom structure. The manufacturing process comprises the steps of cutting, cylinder forming and bonding, folding, inward folding, folding forming and bonding and bottom sealing. The problem of bottom corner gaps is solved, the bottom strength and sealing performance of the paper bag are improved, additional edge covering is not needed, and the production process is simplified.

Description

Technical Field

[0001] This invention relates to the field of paper bag processing technology, and more specifically to an M-bottom paper bag and its manufacturing process. Background Technology

[0002] Modern life requires a large number of paper bags. With the continuous expansion of paper bag varieties, different shapes of paper bags exist on the market, such as figure-eight bottom paper bags or M-bottom paper bags. Among them, the bottom of the M-bottom paper bag is hidden inside after folding, so both front sides of the paper bag are flat surfaces without creases, which has a good aesthetic appeal and is widely used in the market. Currently, there are various M-bottom paper bags with different folding methods on the market. For example, the double-sided center-sealed M-bottom three-dimensional paper bag disclosed in publication number CN211996875U adopts a wrapping mode from bottom to top to make the paper bag. However, the bottom corner of the paper bag is disconnected from the front or side, resulting in a gap at the bottom corner that compromises the bottom strength and sealing of the paper bag. Therefore, this patent uses a bottom binding 5 to cover the gap at the bottom corner, thereby strengthening the bottom.

[0003] However, this method adds an extra step of binding the bottom edge, which firstly increases the number of steps and reduces production efficiency; secondly, this binding method is only a temporary solution, as there are still gaps at the bottom of the paper bag. The binding only covers the external gaps, while there are still gaps at the bottom corners inside the paper bag, and the problem of bottom strength is not completely solved. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the present invention provides an M-bottom paper bag and its manufacturing process. By using a newly designed paper bag die-cutting form and folding method, the bottom corners of the M-bottom paper bag are sealed without gaps, which increases the strength and sealing performance of the bottom of the paper bag.

[0005] To achieve the above objectives, the present invention provides the following technical solution: an M-bottom paper bag, comprising two front surfaces, two side surfaces, and a bottom surface, wherein the bottom surface comprises a first bottom surface located below the front surface and a second bottom surface located below the side surface, and the first bottom surface and the second bottom surface are connected integrally; A fold line extending vertically to the second bottom surface is provided in the middle of the side surface; Near the bottom of the side, there are two first diagonal creases that extend diagonally downwards from the crease to the bottom corner of the paper bag. It also includes a second oblique crease that extends obliquely from the bottom corner of the paper bag toward the first bottom surface, and the first bottom surface forms a fold inside the second oblique crease; The folded portion is folded inward along the second oblique crease and the second bottom surface to the bottom of the paper bag to form a closed bottom corner; The second bottom surface continues to be folded along the fold lines, causing the inner side of the two first diagonal fold lines to fold towards the bag opening along the fold lines to form an M-shaped bottom structure.

[0006] With the above configuration, the first bottom surface and the second bottom surface of the paper bag of the present invention are connected as one piece. At the same time, the folding part is provided to form a closed bottom corner with the second bottom surface when folded inward, so that no gaps appear at the bottom corner, thereby strengthening the strength and sealing of the bottom of the paper bag.

[0007] The invention is further configured such that: a notch is provided at the lower edge of the folded portion; at least a portion of the notch extends toward the direction of the second oblique crease.

[0008] With the above design, the notch makes it less likely to pull on the first bottom surface when the folded part is folded inward together with the second bottom surface, thus avoiding paper damage. It also makes it easier for the folded part to be folded inward into the paper bag, and at the same time, it can control the thickness of the bottom, avoiding excessive thickness at the bottom corners.

[0009] The present invention is further configured such that: the second bottom surface has an extension surface that is longer than the length of the first bottom surface in the length direction.

[0010] The present invention is further configured such that the two sides of the extended surface have narrowing structures.

[0011] The invention is further configured such that two front sides and two side sides form a three-dimensional bag body in a surrounding manner, and the joint is provided with a side adhesive part for adhesive bonding.

[0012] The present invention is further configured such that the folded portion is adhesively connected to the second bottom surface.

[0013] The present invention is further configured such that: one of the two first bottom surfaces is provided with a bottom sealing adhesive part, and the other first bottom surface is glued to the bottom sealing adhesive part.

[0014] This invention further provides a manufacturing process for an M-bottom paper bag, comprising the following steps: Step 1: Cut the paper to the appropriate size; Step 2: Wrap the paper into a tube and glue it together to form a three-dimensional paper bag that opens at the top and bottom; Step 3: Fold the paper bag along the creases to flatten it; Step 4: Unfold the paper bag again, and fold the second bottom surface and the folded part inwards towards the bottom of the paper bag; Step 5: Fold the second bottom edge inward along the fold lines into the paper bag; fold the paper bag flat again so that the sides form an M-shaped bottom structure; Step 6: Seal the two bottom surfaces of the paper bag together to complete the paper bag processing.

[0015] With the above setup, step 3 folds the paper bag once to make the side of the paper bag tend to fold inwards. Then, in steps 4 and 5, the paper bag is unfolded again and folded inwards. When folding inwards again, the side of the paper bag is ensured to fold inwards rather than outwards.

[0016] The present invention further includes, in step 6: Step 6.1: Unfold the paper bag again, fold the first bottom edge of both sides of the paper bag inwards and glue them together; Step 6.2: Fold the first bottom surface of the paper bag further inwards until the first bottom surface is tucked into the bottom of the paper bag along with the M-shaped bottom structure formed by the side surface; Step 6.3: Fold the completed paper bag back into a flat shape.

[0017] The present invention is further configured such that, in step 4, the degree of opening of the bag opening is less than or equal to the degree of opening of the bag bottom.

[0018] With the above settings, since the bottom of the bag needs to be fully opened to facilitate the inward folding of the second bottom surface, the sides of the paper bag in the bottom area will disrupt the original folding trend inward, making it easy to fold outward when refolding. However, by setting the opening of the bag to be no more than the bottom, the sides of the paper bag in the opening area retain the original folding trend inward. Guided by this trend, folding the sides of the opening inward can also cause the sides of the bottom to fold inward, thus avoiding the problem of the sides of the paper bag potentially folding outward.

[0019] In summary, the present invention has the following beneficial effects: The first bottom surface and the second bottom surface of the paper bag of the present invention are connected as one piece. At the same time, a second oblique fold extending from the first bottom surface is provided at the bottom corner, and a folded part is formed on the inner side of the first bottom surface along the second oblique fold. When the second bottom surface is folded inward in the future, the second bottom surface and the folded part will be folded inward together to the bottom of the paper bag, so that the bottom corner is completely covered, avoiding gaps at the bottom corner, and improving the strength and sealing of the bottom of the paper bag. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the unfolded structure of a paper bag.

[0021] Figure 2 This is a diagram illustrating the action of folding a paper bag in half.

[0022] Figure 3 This is a diagram illustrating the inward folding of the second bottom surface of the paper bag.

[0023] Figure 4 This is a schematic diagram illustrating the process of forming the M-shaped bottom structure of a paper bag.

[0024] Figure 5 This is a schematic diagram illustrating the process of sealing the bottom of a paper bag with adhesive.

[0025] Reference numerals: 01, fold line; 02a, first diagonal fold line; 02b, second diagonal fold line; 11, bottom corner; 1, front; 2, side; 3, bottom surface; 31, first bottom surface; 31a, folded part; 31b, remaining part; 32, second bottom surface; 321, extended surface; 4, inverted V-shaped notch; 5, side adhesive part; 6, bottom adhesive part. Detailed Implementation

[0026] The present invention will be further described in detail below with reference to the accompanying drawings.

[0027] This embodiment discloses an M-bottom paper bag, the unfolded diagram of which is shown below. Figure 1 As shown, the bag includes two front surfaces 1, two side surfaces 2, and a bottom surface 3. The bottom surface 3 includes a first bottom surface 31 located below the front surface and a second bottom surface 32 located below the side surface. The adjacent portions of the first bottom surface 31 and the second bottom surface 32 are connected as a whole, so that the bottom surface 3 of the paper bag forms an integral structure. At the same time, a fold line 01 extending vertically to the second bottom surface 32 is provided in the middle of the side surface 2 for folding the side surface 2. Near the bottom of the side surface 2, there are two first oblique fold lines 02a extending diagonally downward from the fold line 01 to the bottom corner 11 of the paper bag. Preferably, the starting position of the first oblique fold line 02a is half the width of the side surface 2, extending upward from the dividing fold line between the second bottom surface 32 and the side surface 2. In this way, when folded, the part of the M-shaped bottom structure formed along the first oblique fold line 02a is exactly flush with the starting position of the first oblique fold line 02a, ensuring the aesthetics of the formed M-shaped bottom structure.

[0028] The paper bag of the present invention also includes a second oblique fold 02b extending obliquely from the bottom corner 11 of the paper bag toward the first bottom surface 31, and a folded portion 31a is formed inside the second oblique fold 02b of the first bottom surface 31; wherein, the bottom corner 11 is the position of the four corners of the bottom surface 3 after the paper bag is formed. In the prior art, the bottom surface, side surface and front surface of the paper bag are broken at the bottom corner 11 position to facilitate folding, resulting in a gap at the bottom corner 11 after subsequent folding, which reduces the strength and sealing of the bottom of the paper bag. The present invention, by setting the second oblique fold 02b, refers to... Figure 3 When the second bottom surface 32 is folded inward, the folded portion 31a folds inward along the second oblique crease 02b and the second bottom surface 32 toward the bottom of the paper bag, thereby closing the bottom corner 11 with the second bottom surface 32 and the folded portion 31a. This closing method is formed by a specific paper folding structure, which is different from the traditional method of setting an extra part for edge binding. The paper bag of the present invention does not require an extra process to form a closed bottom corner 11, and the bottom corner 11 is closed both inside and out, which improves the strength and sealing of the bottom of the paper bag.

[0029] Further reference Figure 4 The second bottom surface 32 continues to be folded along the fold line 01, causing the inner side of the side surface 2 located on the two first diagonal fold lines 02a to fold along the fold line 01 towards the bag opening, finally forming a paper bag with an M-shaped bottom structure; the two front surfaces 1 of the paper bag are flat and without creases, and have a very good appearance.

[0030] Furthermore, to facilitate the folding part 31a's easy insertion into the bottom of the paper bag when folded inward together with the second bottom surface 32, a notch 4 is preferably provided inside the second oblique crease 02b. This notch can be any suitable geometric shape for folding; in this embodiment, it is preferably an inverted V-shape. First, the notch allows the folding part 31a to have a relatively small area and reduces the tension interference between it and the remaining part 31b of the first bottom surface 31, making it easier for the folding part 31a to fold inward together with the second bottom surface 32. Second, the notch 4 extends to the second oblique crease 02b. By actively setting the notch 4, the folding part 31a folds inward along the notch in addition to the second oblique crease 02b, ensuring the accuracy of the folding position and avoiding paper damage during folding. Third, the notch 4 also reduces the paper thickness in the bottom corner 11 area to a certain extent, ensuring that the bottom of the paper bag does not protrude too much and maintaining aesthetics.

[0031] Furthermore, since a portion of the first bottom surface 31 forms a fold 31a, the length of the remaining portion 31b becomes shorter. To ensure good adhesion and support between the remaining portion 31b and the second bottom surface 32 during the subsequent sealing of the paper bag bottom, the second bottom surface 32 is provided with an extension surface 321 that is longer than the first bottom surface 31 in the length direction. The extension surface 321 extends further into the paper bag after folding inwards. Using glue on the extension surface 321 further enhances the support and adhesion between the remaining portion 31b and the second bottom surface 32, ensuring the strength of the bottom of the paper bag. However, due to the longer extension surface 321, it is more likely to obstruct the first bottom surface 31 during inward folding. Therefore, it is preferable that the extension surface 321 has narrowing structures on both sides to ensure that it does not obstruct the first bottom surface 31 during inward folding.

[0032] Furthermore, in this embodiment, the paper bag is manufactured by forming a tube, that is, the two front sides 1 and the two side sides 2 form a three-dimensional bag body in a wrap-around manner, and the joint between the separated side sides and the front sides is provided with a side adhesive part 5 for adhesive bonding. In the above way, the paper bag of the present invention can be manufactured using existing tube forming automated equipment, which is convenient to produce, highly versatile, and the production cost is effectively controlled.

[0033] To further strengthen the bottom of the paper bag, the folded portion 31a is glued to the second bottom surface 32, preferably with reference to... Figure 5The glue is placed at the glue mark 7 so that when the bottom surface 31 is sealed, the glue can simultaneously contact and bond with the folded part 31a and the remaining part 31b, thereby increasing the strength of the bottom of the paper bag.

[0034] Furthermore, one of the two first bottom surfaces 31 is provided with a bottom sealing adhesive part 6. During the bottom sealing process, glue is sprayed onto the outside of the bottom sealing adhesive part 6, and then the other first bottom surface 31 is glued to the bottom sealing adhesive part 6. This completes the bottom sealing of the paper bag.

[0035] This embodiment further provides a manufacturing process for an M-bottom paper bag, which includes the following steps for manufacturing the aforementioned M-bottom paper bag: Step 1: Cut out the paper of the corresponding size and press fold line 01, first diagonal fold line 02a and second diagonal fold line 02b on it; at the same time, press the corresponding dividing fold lines at the dividing points of the front, side and bottom of the paper bag. Step 2: Wrap the front and sides together to form a tube and glue them together to create a three-dimensional paper bag that opens at the top and bottom; Step 3: Refer to Figure 2 Fold the paper bag along the fold line 01 to make it flat; this will deepen the fold line 01 and make the side 2 of the paper bag tend to fold inward. Step 4: Refer to Figure 3 Unfold the paper bag again and fold the second bottom surface 32 and the fold 31a inward toward the bottom of the paper bag. It should be noted that when unfolding the paper bag again, the opening of the bag opening should be less than or equal to the opening of the bottom of the bag. The purpose of this is to make the bottom of the bag fully open so that it can be folded inward, while the opening of the bag should not be fully opened, or at least should not be opened to a degree greater than that of the bottom of the bag. This allows the sides of the paper bag to retain the inward folding tendency formed in step 3, which is convenient for subsequent refolding.

[0036] Step 5: Refer to Figure 4 Fold the second bottom surface 32 inward along the fold line 01 into the paper bag; the second bottom surface 32 is folded from the bottom of the bag to the opening of the bag, and the side surface 2 is folded back into a folded shape, so that the paper bag is folded back into a flat shape, and the side surface 2 also forms an M-bottom structure.

[0037] Step 6: Finally, glue and seal the two bottom surfaces 31 of the paper bag to complete the paper bag processing. Through the above steps, using a folding, unfolding, and refolding process, the paper is stably folded according to the set folding method, ensuring processing reliability and reducing the possibility of folding.

[0038] Furthermore, this embodiment refers to Figure 5 Step 6 specifically includes: Step 6.1: Unfold the paper bag again, apply glue to the bottom adhesive part, fold the first bottom surface 31 of the two front sides 1 of the paper bag inward and glue them together; Step 6.2: After gluing, continue to fold the first bottom surface 31 of the paper bag inwards, so that the first bottom surface 31 is placed in the bottom of the paper bag along with the M-shaped bottom structure formed by the side 2; in this way, the bottom of the paper bag is completely hidden inside, making the front of the paper bag seamless and beautiful.

[0039] Step 6.3: Finally, fold the completed paper bags back into a flat shape for continued transport and stacking.

[0040] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the design concept of the present invention should be included within the protection scope of the present invention.

Claims

1. A M bottom paper bag comprising two of front faces (1), two of side faces (2) and a bottom face (3), characterized in that: The bottom surface (3) comprises a first bottom surface (31) below the front surface and a second bottom surface (32) below the side surface, and the first bottom surface (31) and the second bottom surface (32) are connected integrally; The middle part of the side surface (2) is provided with a folding mark (01) extending vertically to the second bottom surface (32); The side surface (2) is provided with two first oblique folding marks (02a) extending obliquely downward from the folding mark (01) to the bottom corner (11) of the paper bag, Further comprising a second oblique folding mark (02b) extending obliquely from the bottom corner (11) of the paper bag to the first bottom surface (31), and the first bottom surface (31) forms a folding part (31a) on the inner side of the second oblique folding mark (02b); The folding part (31a) is folded together with the second bottom surface (32) along the second oblique folding mark (02b) to form a closed bottom corner; The second bottom surface (32) is further folded along the folding mark (01), and the side surface (2) located on the inner side of the two first oblique folding marks (02a) is folded along the folding mark (01) to form an M-bottom structure.

2. A M-bottom paper bag according to claim 1, characterized in that: The lower edge of the folding part (31a) is provided with a notch (4), and at least part of the notch (4) extends to the second oblique folding mark (02b).

3. A M-bottom paper bag according to claim 1, wherein: The second bottom surface (32) is provided with an extension surface (321) longer than the first bottom surface (31) in the length direction.

4. A M-bottom paper bag according to claim 3, wherein: The two sides of the extension surface (321) have a narrowing structure.

5. A M-bottom paper bag according to claim 1, wherein: The two front surfaces (1) and the two side surfaces (2) form a three-dimensional bag body in a surrounding form, and the joint part is provided with a side adhesive part (5) for adhesive connection.

6. A M-bottom paper bag according to claim 1, wherein: The folding part (31a) and the second bottom surface (32) are adhesively connected.

7. A M-bottom paper bag according to claim 1, wherein: One of the two first bottom surfaces (31) is provided with a bottom sealing adhesive part (6), and the other first bottom surface (31) is adhesively connected with the bottom sealing adhesive part (6).

8. A process for making M-bottom paper bags as claimed in claim 1, wherein: The method comprises the following steps: Step 1: cutting paper of corresponding specifications; Step 2: winding the paper into a cylinder and adhering to form a three-dimensional paper bag with the top and bottom open; Step 3: folding the paper bag inward along the folding mark (01) to flatten it; Step 4: unfolding the paper bag again, and folding the second bottom surface (32) and the folding part (31a) inward to the bottom of the paper bag; Step 5: continuing to fold the second bottom surface (32) inward along the folding mark (01); unfolding the paper bag again to form an M-bottom structure of the side surface (2); Step 6: adhering the two first bottom surfaces (31) of the paper bag to seal the bottom, and completing the processing of the paper bag.

9. A fabrication process as claimed in claim 8, wherein: In the step 6, further comprising: Step 6.1: unfolding the paper bag again, and folding and adhering the first bottom surface (31) of the two front surfaces (1) inward; Step 6.2: continuing to fold the first bottom surface (31) inward, and making the first bottom surface (31) be accommodated in the bottom of the paper bag along with the M-bottom structure of the side surface (2); Step 6.3: unfolding the completed paper bag to flatten it.

10. The manufacturing process of claim 8, wherein: In the step 4, the opening stroke of the bag opening is less than or equal to the opening stroke of the bag bottom.

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