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EP-4309879-B1 - METHODS FOR ALTERING PORTIONS OF SUBSTRATES WITH VIBRATION ENERGY

EP4309879B1EP 4309879 B1EP4309879 B1EP 4309879B1EP-4309879-B1

Inventors

  • LENSER, TODD DOUGLAS
  • MYERS, RANDALL ALLEN

Dates

Publication Date
20260506
Application Date
20230606

Claims (14)

  1. A method of altering a portion (210) of a substrate (200) comprising: providing a first device (300) comprising an outer surface (302); providing a plurality of recesses (308) in the outer surface (302) of the first device (300), wherein the recesses (308) have a shape (310) configured to produce projections (214) suitable for use in a touch fastener; providing a second device (400) comprising a rotating source of vibration energy (404); forming a nip (800) between the rotating source of vibration energy (404) and the outer surface (302); conveying the substrate (200) through the nip (800); altering the portion (210) of the substrate (200) in the nip (800) using the rotating source of vibration energy (404), wherein the rotating source of vibration energy (404) applies a lineal force of about 1 kN to about 5 kN per 25 mm of operative contact width, wherein the rotating source of vibration energy (404) has an about 20 to about 60 micron zero-to-peak sinusoidal amplitude, and wherein the rotating source of vibration energy (404) applies about 15 kHz to about 29 kHz of vibration energy to the substrate.
  2. The method of Claim 1, wherein the rotating source of vibration energy (404) applies vibration energy to the substrate (200) intermittently.
  3. The method of Claim 1 or Claim 2, comprising imparting thermal energy to the portion (210) of the substrate (200) upstream of the nip (800) to heat the portion (210) of the substrate (200) to a temperature below a melting temperature of the portion (210) of the substrate (200), wherein the temperature below the melting temperature of the portion (210) of the substrate (200) is in a range of about 90 degrees C to about 160 degrees C.
  4. The method of Claim 3, comprising hindering the thermal energy from reaching the rotating source of vibration energy (404), other portions (212) of the substrate (200), and/or the nip (800).
  5. The method of any one of Claims 1 to 4, comprising rotating the first device (300) at a first surface velocity different than a second surface velocity of the rotating source of vibration energy (404).
  6. The method of Claim 5, wherein the first surface velocity is variable, or wherein the second surface velocity is variable.
  7. The method of Claim 5, wherein the first surface velocity is higher than the second surface velocity.
  8. The method of Claim 5, wherein the first surface velocity is lower than the second surface velocity.
  9. The method of any one of Claims 1 to 8, comprising cooling the rotating source of vibrational energy (404) or the first device (300).
  10. The method of any one of Claims 1 to 9, wherein the second device (400) is a rotary sonotrode (406), and wherein the vibration energy is ultrasonic energy.
  11. The method of any one of Claims 1 to 10, wherein the substrate (200) comprises more than one layer (216) or more than one material.
  12. The method of any one of Claims 1 to 11, comprising contacting the substrate (200) with a substrate spreader (700) upstream of the nip (800) to reduce fold over or wrinkles in the substrate (200).
  13. The method of Claim 3, comprising applying the thermal energy to a first side (206) of the substrate (200).
  14. The method of Claim 13, comprising applying the thermal energy to a second side (208) of the substrate (200).

Description

FIELD The present disclosure relates generally to altering portions of substrates with vibration energy and more specifically to forming touch fasteners in substrates with ultrasonic energy. BACKGROUND The discussion of shortcomings and needs existing in the field prior to the present disclosure is in no way an admission that such shortcomings and needs were recognized by those skilled in the art prior to the present disclosure. Sources of vibration energy in combination with an anvil may be used to create bonds in one or more substrates conveyed therebetween and/or to create surface features in one or more substrates conveyed therebetween. Surface features may include projections or hooks, as may be useful in hook and loop fasteners. The sources of vibration energy may use ultrasonic energy. The source of vibration energy may press against the substates to melt, to soften, and/or to deform a portion of the substrates where a bond is desired. To form the projections or hooks, the substrate(s) is/are conveyed through a nip between a source of vibration energy and an anvil with a plurality of projection recesses defined therein. The source of vibration energy presses against the substrate to melt, to soften, and/or to deform a portion of the substate into a deformable film that may flow, stretch, and/or otherwise deform into the plurality of projection recesses. The substrate(s) may then be moved out of the nip and the substrate may be removed from the anvil, resulting in a substrate having a plurality of projections or hooks in some regions, melted substrate around the projections or hooks, and/or normal nonwoven or film in other regions (non-melted regions). The plurality of projections may form one side of a touch fastener for an absorbent article. US2003/0,188,819A1, EP1,112,139 and US2016/036,8201A1 disclose different methods for obtained improved ultrasonic bond strength. Existing processes for forming a touch fastener hook patch between a blade-style sonotrode and an anvil roll have multiple failure modes and may only be operated at limited line speeds. Holes, tears, incomplete hook formation, and hard ridges may be observed in the patch, including but not limited to at the trailing edge of the patch. The blade-style sonotrode may have localized high temperature regions, which may burn through a substrate and cause holes or tears. For example, shear stresses in the hot polymer near the stationary sonotrode and the rotating anvil roll may lead to holes in the patch. The hooks formed in the non-woven substrate by the existing processes may have low structural integrity in the region of the base of the hook near the membrane of the substrate and may, therefore, fracture. Existing processes may also be sensitive to the patch shape and the intermittent nature of the patches, which limits product design options. In particular, the shaped patches may require a significant in-nip area balance, which often constrains variation of the cross-directional (CD) width of the patch through the machine-directional (MD) length of the patch. "Area balance" as used herein refers to the area of substrate intermediate the sonotrode and anvil at any instant in time of revolution of the mold roll. A high imbalance may lead to mechanical vibration and uneven forces in the process. Further, process parameters such as applied force, amplitude, and/or frequency of the ultrasonic vibration may be difficult to control throughout a patch with prior art. Shaped and/or intermittent patch shapes and/or higher line speeds may make such process control even more difficult. A need, therefore, exists for a method and apparatus to create shaped patterns of intermittent touch fasteners in a non-woven at higher line rates without quality defects. SUMMARY The invention relates to a method of altering a portion of a substrate as further defined in the claims. The method comprises providing a first device comprising an outer surface; providing a second device comprising a source of vibration energy; forming a nip between the source of vibration energy and the outer surface; conveying the substrate through the nip; and applying vibration energy from the source of vibration energy to the substrate in the nip to alter the portion of the substrate. According to various embodiments, the method may also comprise applying thermal energy to a portion of the substrate upstream of the nip to raise a temperature of the portion of the substrate to a temperature below a melting temperature of the portion of the substrate. The temperature below the melting temperature of the portion of the substrate may be in the range of about 90 degrees C to about 160 degrees C. To mitigate fold over or wrinkles in the substrate, particularly in embodiments that apply thermal energy to the portion of the substrate, the method may further comprise conveying the substrate into contact with a substrate spreader upstream of the nip. The thermal energy may have a temperature in