Method for inspecting adhesive patterns on product packaging

Abstract

The present invention relates to a non-destructive, non-invasive method for inspecting the adhesive pattern of a package of a product such as a patch or a pharmaceutical patch. The method comprises thermally probing the package and the adhesive pattern and retrieving its thermal response. The inspection is based on thermal response analysis.

Description

Technical Field

[0001] The present invention relates to the packaging of articles such as sanitary products, in particular patches for medical use or medicated patches, which involves bonding layers of packaging material around the packaged article along a bonding pattern. The invention has been developed in particular with reference to a bonding pattern involving heat activation of the bonding. Background Art

[0002] Figure 1 The manufacturing process of a package PK of an object P, such as a patch or a medication patch, is schematically shown, which features a bonding pattern BP.

[0003] The package PK is usually assembled in the machine 1 by feeding the first web material W1 and the second web material W2 through respective pairs of heating patterned rollers 2, 4. In particular, each pair of heating patterned rollers 2, 4 comprises a first patterned heating roller H2RA, H4RA and a second patterned heating roller H2RB, H4RB arranged on opposite sides of the respective web material W1, W2, the respective web materials passing the rollers H2RA, H2RB and H4RA, H4RB along respective feed directions F1, F2. The feeding of the web material W1 and the web material W2 through the rollers H2RA, H2RB and H4RA, H4RB results in providing a heating pattern HP1, HP2 ( Figure 1a ).

[0004] The heating patterns are arranged on surfaces of the web materials W1, W2 which face each other when the materials W1, W2 are incorporated into the package P. The positions of the heating patterns HP1, HP2 are as follows: Figure 1 As shown. One of the web materials W1, W2 is coated with a glue layer, in particular a heat-activated adhesive layer, which only exhibits significant adhesive properties when heated above a predetermined temperature. Therefore, providing the heating pattern HP1, HP2 also brings about the activation of the adhesive layer on the web material W1 (or W2, equivalently).

[0005] The feeding of the web materials W1, W2 having the heating patterns HP1, HP2 thereon continues to pass through a third pair of rollers 6, specifically a pair of bonding rollers R6A, R6B, which are arranged on opposite sides of the merged layered arrangement of the web materials W1, W2. Unlike the rollers in the roller pairs 2, 4, the bonding rollers R6A, R6B are not heated, but are only used to press the web materials W1, W2 against each other to achieve bonding between the web materials at the heating patterns HP1, HP2: the compression of the heated layered arrangement of the web materials W1, W2 forms a bonding pattern BP at the overlap between the heating patterns HP1, HP2, one of which is also characterized by a heat-activated adhesive layer and seals the web materials W1 and W2 together, thereby packaging the product P, as Figure 1b shown.

[0006] It should be noted that the provision of the heating patterns HP1 and HP2 is timed so that they completely overlap when passing through the bonding rollers R6A and R6B in order to maximize the bonding strength and ensure the airtightness of the bonding pattern itself, such as maintaining the characteristics of the product P (e.g., sterility), otherwise if the bonding pattern is not airtight, the characteristics of the product P will be deteriorated.

[0007] However, over time, the timing between the roller pairs may be partially lost due to slippage between the web material W1, W2 and the rollers in the roller pairs 2 and / or 4 and / or 6, as well as material stretching due to thermal hysteresis, etc. Therefore, due to the loss of timing, the heating patterns HP1, HP2 lack overlap and the characteristics of the bonding pattern BP will be exposed to significant degradation, which in turn leads to a loss of bond strength and a loss of closed bond perimeter. To date, there has been no quality control of the bonding pattern BP, so the manufacturer has been forced to adopt a fixed maintenance schedule to restore the correct timing of the web material W1, W2 passing through the roller pairs 2, 4, 6. This may lead to unnecessary costs in an essentially unpredictable manner due to a tighter maintenance schedule than necessary, or it may lead to quality degradation before the scheduled maintenance is performed. In other words, when making the bonding pattern BP, it is not known what the actual operating conditions of the machine 1 are and it is virtually impossible to decide whether and when to correct the timing. Summary of the invention

[0008] The object of the present invention is to solve the above technical problems. In particular, one object of the present invention is to improve the consistency of the quality of the bonding pattern of product packaging made of bonded web material layers. Another object of the present invention is to monitor the actual operating conditions of the bonding process to determine whether and when correction (e.g., restoration timing) is required.

[0009] The objects of the invention are achieved by a method having the features specified in the following claims, which form an integral part of the technical disclosure provided herein in relation to the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Further features and advantages of the invention will become apparent from the following description made with reference to the accompanying drawings, provided by way of non-limiting example only, in which:

[0011] Figure 1 is a schematic diagram of a manufacturing method and machine according to the prior art, wherein Figure 1a and 1b The characteristics of this method are shown,

[0012] Figure 2 is equivalent to Figure 1 Schematic diagram of the invention, but relates to a manufacturing method and a machine according to the invention, wherein Figure 2a and 2b The characteristics of this method are shown,

[0013] 3 and 4 comprise a part a and a part b respectively, which illustrate functional aspects of the method according to the invention. DETAILED DESCRIPTION

[0014] Through a general introduction, Figure 1 Items associated with the same reference numerals that have been used in the present invention represent the same components / devices / units, unless otherwise specified. Therefore, the general description of the same components / devices / units will not be repeated. Instead, it should be understood that the same components / devices / units that have been used in the present invention are not repeated. Figure 1 The description made continues to apply.

[0015] refer to Figure 2 4 , the method for checking the bonding pattern BP of the package PK of the product P (e.g., a patch or a drug patch) according to the present invention is basically carried out by providing a heat detection device 8 at the output end of the machine 1, specifically downstream of the bonding position of the web materials W1 and W2 corresponding to the roller pair 6 of the bonding rollers R6A, R6B. The heat detection device 8 is configured to perform heat detection on the bonding pattern BP and the package PK when the continuous flow of the bonded web materials W1, W2 leaves the bonding rollers R6A, R6B to detect the thermal response of the bonding pattern BP and the rest of the package PK ( Figure 2b ).

[0016] In various embodiments, the method according to the present invention comprises:

[0017] - feeding a first web material W1 , in particular along a first feed direction F1 ,

[0018] - providing a first heating pattern HP1 on the first web material W1, in particular providing the pattern HP1 on one side thereof when passing through a pair of heated patterning rollers HR2A, HR2B,

[0019] - feeding the second web material W2, in particular along a second feeding direction F2 (in the embodiment of the figures, F2 is parallel to F1, but this is not mandatory and depends on the overall structure of the machine 1); coating at least one (preferably one) of the first web material W1 and the second web material W2 with an adhesive layer as disclosed above and providing a corresponding heating pattern at the adhesive layer;

[0020] - providing a second heating pattern HP2 on the second web material, in particular providing the pattern HP2 on one side thereof when passing through a pair of heated patterned rollers HR4A, HR4B,

[0021] - sending the first web material W1 and the second web material W2 to a bonding position corresponding to the roller pair 6 of bonding rollers R6A, R6B, wherein the first heating pattern HP1 and the second heating pattern HP2 face each other; sending comprises feeding the two web materials W1, W2 so as to merge along a new feed direction corresponding to the machine direction MD;

[0022] - bonding the first web material W1 to the second web material W2 by pressing the first heating pattern HP1 against the second heating pattern HP2, thereby defining a bonding pattern BP at an overlapping area of ​​the first heating pattern HP1 and the second heating pattern HP2; it is also noted that before merging the web materials W1, W2 at the bonding location, a product P is fed between the web materials such that the product P remains enclosed within the bonding pattern BP while the web materials W1, W2 are being bonded;

[0023] - thermally probing the bonding pattern BP and the package P and detecting their thermal response; the thermal response peaks at the heating patterns HP1, HP2 compared to the package (P) because the heating patterns have a higher temperature than the package due to the local heating of the roller pairs 2, 4;

[0024] - Comparing the shifts between subsequent peak positions of the thermal response of the bonding pattern with a reference shift L.

[0025] Each of the above method steps will now be disclosed in further detail.

[0026] Basically, the manufacture of packaging PK is based on Figure 1 The heat detection device 8 can be implemented in the same way as already disclosed in the previous embodiment: finally, the package PK output by the machine 1 should not be subjected to any changes to allow the inspection method according to the invention. This is one of the technical advantages of the invention: the manufacturing steps and the packaging characteristics remain unchanged, because the method is non-destructive and non-invasive. The heat detection device 8 can include, for example, an infrared camera or a pyrometer, and can be arranged only on one side of the package PK as in the preferred embodiment or as in the example of Figure 2a Detection devices 8, 8* are arranged on both sides as schematically shown in FIG. This applies to any specific device (infrared camera, pyrometer, etc.).

[0027] Figure 3a represents a bonding pattern BP with completely overlapping heating patterns HP1 and HP2. Figure 3aRepresents an operating condition of the machine 1 that is well within design specifications, typically found at the beginning of a production cycle, for example after regular maintenance / timed restoration of the machine 1. The heating patterns HP1 and HP2 are both aligned and show essentially no staggering along the machine direction MD. When detected by the thermal detection device 8, the package PK comprising the bonding pattern BP recovers a thermal response that peaks at the bonding pattern BP because the bonding pattern has a higher temperature than the rest of the package due to thermal interaction with the rollers HR2A, HR2B and HR4A, HR4B. In the case of two identical heating patterns HP1 and HP2 having a closed perimeter and a spacing L along the machine direction MD, where the spacing L is the distance between two opposite sides of the closed perimeter of the completely overlapping heating patterns HP1 and HP2 (in this case along the machine direction MD), the peaks P1 and P2 have a distribution (in Figure 3b The curve diagram shows the time-t distribution, which is of course proportional to the spatial distribution of the flow velocity of the package PK along the machine direction MD), which distribution corresponds to the distribution of the opposite sides of the closed perimeter, i.e. they are separated by a spacing KL along the machine direction MD, which is proportional to the spacing L along the machine direction MD, as described, through the flow velocity of the package PK along the machine direction MD.

[0028] The inter-peak sections of the thermal response curve correspond to areas of the package where the heating patterns HP1 , HP2 are not active, ie are substantially unheated: this means that in this operating condition the inter-peak sections of the graph show substantially no further peaks in the thermal response. Figure 3b The peak-to-peak distance KL is the reference offset of the thermal response: under operating conditions according to the design specifications, the spatial distribution of the thermal response is characterized by separate, well-defined peaks P1, P2, P3, with no peak staggering or repetition.

[0029] It should be noted that according to the present invention, a peak in the thermal response means an appropriate signal peak, such as the output signal (voltage or current) from a pyrometer probing the package PK, or means a temperature-related data display having characteristics corresponding to high / higher temperature values. For example, when the thermal detection device is an infrared camera, the output is typically a false color (e.g. grayscale) image of the area framed by the camera, where the peaks in the thermal response are associated with brighter areas - this is typically applicable to thermal images, which are post-processed into false color images, where warm colors (e.g. red, orange, yellow) are "peaks" within the meaning of the present disclosure, i.e. associated with higher temperature areas. In addition, based on the typical processing speed of the machine 1, the thermal detection is preferably performed based on a sampling time of 1 ms or less.

[0030] Now go to Figure 4a, which shows a bonding pattern BP' with incompletely overlapping heating patterns HP1 and HP2 (in other words, staggered heating patterns HP1, HP2). Figure 4a Represents an operating condition of the machine 1 that has exceeded the design specification and that could potentially result in a defective package (e.g., unsealed). This situation typically occurs during a production cycle, such as when a considerable number of packages PK have been manufactured after a scheduled maintenance / timed recovery of the machine 1.

[0031] The heating patterns HP1 and HP2 are no longer aligned and substantially present a staggered L' along the machine direction MD.

[0032] When detected by the thermal detection device 8, the package PK including the bonding pattern BP resumes a thermal response, just as it occurs in the case of completely overlapping heating patterns HP1, HP2, which thermal response reaches a peak at the bonding pattern BP because the bonding pattern has a higher temperature than the rest of the package due to thermal interaction with rollers HR2A, HR2B and HR4A, HR4B.

[0033] However( Figure 4b ), since the bonding pattern BP now features staggered heating patterns HP1, HP2, Figure 3b In contrast, the thermal response peaks appear at multiple locations. Specifically, a peak will be generated in the thermal response and move along the machine direction MD, with a total of four peaks at HP1-HP2-HP1-HP2. Figure 4b represents an embodiment of the method of the invention, in which the heat detection device is arranged only on one side of the package PK, e.g. Figure 2 8 on the top side visible in FIG. Therefore, thermal detection of the heating pattern of the top layer (web material W1, HP1) will produce a much stronger thermal response than the heating pattern of the bottom layer (web material W1, HP2), which will be attenuated by the intervening top layer. Figure 4b The thermal response in the presents peaks P1, P1' corresponding to the thermal response at the heating patterns HP1, HP2 that first appear along the machine direction MD and peaks P2, P2' corresponding to the thermal response at the heating patterns HP1, HP2 that appear again along the machine direction MD (peaks P3, P3' are equivalent to peaks P1, P1', except that they refer to adjacent bonding patterns BP). Due to the above-mentioned attenuation, the peaks P1', P2' have amplitudes lower than the amplitudes of the peaks P1, P2.

[0034] like Figure 4bAs shown, the peaks P1 and P1' are offset by a distance KL', which is proportional to the staggered offset L' of the flow speed of the package PK along the machine direction MD, wherein the staggered offset L' of the staggered heating patterns HP1 and HP2 is shorter than the spacing L, so the distance KL' is shorter than the distance KL (the coefficient of the proportion is the same because it depends on the speed of the package PK along the direction MD).

[0035] Short offsets between subsequent peaks, especially offsets shorter than the reference offset KL, are evidence of staggered heating patterns due to timing problems in machine 1.

[0036] In the case of two identical heating patterns HP1 and HP2 having a closed perimeter and a spacing L along the machine direction MD, wherein the spacing L is the distance between two opposite sides of the closed perimeter (in this case along the machine direction MD) of the completely overlapping heating patterns HP1 and HP2, the peaks P1 and P2 have a distribution (in Figure 3b The distribution of the peaks P1' and P2' in the graph of the thermal response corresponds to the distribution of the opposite sides of the closed perimeter, i.e. they are spaced apart by the same spacing L in the machine direction MD, while the peaks P1' and P2' have a distribution which reflects (except for the amplitude) the distribution of the peaks P1, P2, only shifted in space due to the staggering. The inter-peak sections of the thermal response curve correspond to the areas of the package where the heating patterns HP1, HP2 are not active (i.e. areas that are substantially unheated) and are shorter than they would be under operating conditions without timing problems: this means that under operating conditions outside the design specification, the inter-peak sections of the graph show evidence of further peaks in the thermal response. Figure 3b The peak-to-peak distance KL' is lower than the reference offset KL of the thermal response.

[0037] Note that the same considerations apply when the heat detection device 8 is duplicated on the opposite side of the package PK. Figure 3b The graph of FIG. 4 will not change, except for the greater amplitude of the thermal response due to the two detection devices 8, 8* directly collecting the thermal response of the patterns HP1, HP2, which is not attenuated by the intervening layer of web material W1 or W2. The graph of FIG. 4 will show staggered peaks P1, P1' and P2, P2' of the same or substantially the same amplitude, again due to the fact that the intervening layer of web material W1 or W2 does not attenuate the thermal response.

[0038] It should be noted that the above method also applies to bonding patterns without closed perimeters and even, in the limiting case, to linear bonding patterns transverse to the machine direction MD: in the latter case, the reference offset in the thermal response will be zero value and any peak offset in the thermal response of the same bonding pattern will provide evidence of staggering of the heating patterns and therefore suggest retiming of the machine 1. Note also that the same criteria can be applied to the patterns HP1, HP2 shown in the figure: by signal (or image, in the case where the detection means comprises an infrared camera) analysis, the signal peaks can be identified and whenever the thermal response associated with a single overlapping area of ​​the heating patterns HP1, HP2 presents an offset peak (i.e. a non-zero offset), a timing problem can be detected accordingly.

[0039] Naturally, while the principle of the invention remains unchanged, the details of construction and embodiments may vary widely with respect to what has been described and illustrated purely by way of example, without departing from the scope of the present invention.

Claims

1. A method for verifying a bonding pattern (BP) of a packaging (PK) of a product (P), the method comprising: - feeding a first web material (W1), - providing a first heating pattern (HP1) on said first web material, - feeding a second web material (W2), - providing a second heating pattern (HP2) on said second web material, - sending the first web material (W1) and the second web material (W2) to a bonding position, wherein the first heating pattern (HP1) and the second heating pattern (HP2) face each other, - bonding the first web material (W1) to the second web material (W2) by pressing the first heating pattern (HP1) against the second heating pattern (HP2), thereby defining a bonding pattern (BP) at an overlapping area of ​​the first heating pattern (HP1) and the second heating pattern (HP2), - thermally probing the bonding pattern (BP) and the package (P) and detecting their thermal response, which reaches a peak at the heating pattern (HP1, HP2) compared to the package (P), - comparing the shifts between subsequent peak positions of the thermal response of the bond pattern to a reference shift (KL).

2. The method according to claim 1, wherein: The reference offset (KL) is proportional to the distance between subsequent completely overlapped first and second heating patterns in the bonding pattern (BP).

3. The method according to claim 1 or claim 2, wherein: The first heating pattern (HP1) is identical to the second heating pattern (HP2).

4. The method according to any one of claims 1 to 2, wherein: The thermal probing comprises thermal probing the bonding pattern (BP) and the package (PK) on only one side of the bonding pattern (BP) and the package (PK).

5. The method according to any one of claims 1 to 2, wherein: The thermal probing comprises thermal probing the bonding pattern (BP) and the package (PK) only on opposite sides of the bonding pattern (BP) and the package (PK).

6. The method according to any one of claims 1 to 2, wherein: The thermal detection includes performing thermal detection by an infrared camera.

7. The method according to any one of claims 1 to 2, wherein: The thermal detection includes thermal detection by a pyrometer.

8. The method according to any one of claims 1 to 2, wherein: When the package is moved out of the bonding position, the bonding pattern (BP) and the package (P) are thermally probed.

9. The method according to claim 1 or claim 2, wherein: The bonding pattern (BP) has a closed perimeter, and the reference offset is a distance between opposite sides of the closed perimeter of the first and second heating patterns (HP1, HP2) having a complete overlap.

10. The method according to claim 1, wherein: The providing a first heating pattern (HP1) on the first web material comprises feeding the first web material through a first heating patterned roller pair, and the providing a second heating pattern (HP2) on the second web material comprises feeding the second web material through a second heating patterned roller pair.

11. The method according to claim 10, wherein: The bonding station includes a third bonding roller pair.

12. The method according to claim 1, wherein: At least one of the first web material (W1) and the second web material (W2) is coated with an adhesive layer, the heating pattern being arranged at the adhesive layer.

13. The method according to any one of claims 1 to 2, wherein: The sampling time of the heat detection is 1 ms or shorter.

14. The method according to claim 1, comprising feeding a product (P) at the bonding location before bonding the first web material (W1) to the second web material (W2).

15. Method according to claim 14, comprising bonding the first web material (W1) to the second web material (W2) such that the product (P) remains enclosed within the bonding pattern (BP).

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