US-12616951-B2 - Cooling methods for ultrasonic forming and bonding of polymeric webs

US12616951B2US 12616951 B2US12616951 B2US 12616951B2US-12616951-B2

Abstract

Methods and apparatuses for manufacturing portions of absorbent articles may include or facilitate conveying a substrate through a nip formed between a first device and a second device, transmitting vibrational energy from the second device toward the first device via the nip to alter the substrate, and cooling the second device by transferring thermal energy from the second device.

Inventors

Todd Douglas LENSER
Randall Allen Myers

Assignees

THE PROCTER & GAMBLE COMPANY

Dates

Publication Date: 20260505
Application Date: 20230417

Claims (14)

1 . A method of manufacturing portions of absorbent articles comprising: conveying a substrate through a nip formed between a first device and a second device; transmitting vibrational energy from the second device toward the first device via the nip to alter the substrate; and contact cooling the second device, during the transmitting vibrational energy step, by transferring thermal energy from the second device to a heat sink that is substantially isolated from the vibrational energy; wherein the heat sink is in contact with the second device, and wherein the heat sink has a coefficient of friction in the range of about 0.05 to about 0.4.
2 . The method of claim 1 , wherein the heat sink is thermally coupled to the second device.
3 . The method of claim 1 , wherein the second device is a sonotrode, and wherein the vibrational energy is ultrasonic energy.
4 . The method of claim 1 , wherein the step of transmitting vibrational energy from the second device toward the first device via the nip to alter the substrate is intermittent.
5 . The method of claim 1 , wherein the second device comprises titanium.
6 . The method of claim 1 , comprising conveying a fluid over a portion of the heat sink to cool the heat sink.
7 . The method of claim 1 , comprising providing a cavity in the heat sink, and conveying a cooling fluid through the cavity to cool the heat sink.
8 . The method of claim 1 , comprising providing a projection extending from the heat sink, and conveying a fluid over the projection to cool the heat sink.
9 . The method of claim 1 , comprising providing a plurality of recesses in an outer surface of the first device, wherein each of the plurality of recesses has a shape configured to produce a projection in the substrate suitable for use in a touch fastener.
10 . The method of claim 9 , wherein the step of transmitting vibrational energy from the second device toward the first device via the nip to alter the substrate comprises locally softening a portion of the substrate to force a portion of softened material into at least some of the recesses to form projections suitable for use in a touch fastener.
11 . The method of claim 1 , comprising conveying a second substrate through the nip.
12 . The method of claim 11 , wherein the step of transmitting vibrational energy from the second device toward the first device via the nip to alter the substrate comprises bonding the substrate to the second substrate.
13 . The method of claim 1 , wherein the heat sink material comprises a material having a thermal conductivity higher than a thermal conductivity of a primary material of the second device.
14 . The method of claim 13 , wherein the material is aluminum or brass.

Description

CROSS REFERENCE TO RELATED APPLICATION This application claims the benefit of U.S. Provisional Application No. 63/331,931, filed Apr. 18, 2022, the entire disclosure of which is incorporated herein by reference. FIELD The present disclosure relates generally to forming and bonding substrates via vibrational energy and more specifically relates to cooling methods and apparatuses for ultrasonic forming and bonding of substrates. 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 substrates conveyed therebetween and/or to create surface features in substrates conveyed therebetween. Surface features may include projections or hooks, as may be useful in hook and loop fasteners. More specifically, sources of vibration energy in combination with an anvil may be used to create bonds in substrates conveyed therebetween. Examples of substrates bonded together by sources of vibration energy in combination with an anvil may include but are not limited to nonwoven materials and films of various types, which will be discussed in greater detail hereinafter. Bonds may be formed between nonwoven-nonwoven, film-nonwoven, or film-film. The sources of vibration energy may use ultrasonic energy. The source of vibration energy may press against the substrates to melt, to soften, and/or to deform a portion of the substrates where a bond is desired. The anvil may have a bonding nub around which the substrates are melted. The bonded substrates may have many uses, including but not limited to components of absorbent articles. Additionally or alternatively, sources of vibration energy in combination with an anvil with a plurality of projection recesses formed therein may be used to create projections or hooks in substrates conveyed therebetween. Examples of substrates include but are not limited to films and/or nonwoven materials. These sources of vibration energy may use ultrasonic energy. To form the projections or hooks, the substrate(s) may be 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 substrate 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. Without being bound by theory, vibration energy may create a polymer flow or deformation into the projection recesses and/or against the nubs by heating a nonwoven and/or film via hysteresis losses from repeated compression and expansion of the polymer material in response to the vibration energy. A sonotrode, or ultrasound horn, may press against the polymer material with sinusoidal motion of the working surface of several tens of microns amplitude and a frequency of typically 20-40 kHz. Due primarily to high shear rates from high frequency compression, and aided by elevated temperature, the polymers exhibit shear thinning and flow more easily due to a lower apparent viscosity. The process is inherently inefficient, which may be due to impedance mismatches between the titanium or aluminum sonotrode and the low modulus polymer. Some sources suggest that only about 12% of the applied energy goes into melting the polymer. Due to the high cycle rate, sonotrodes for continuous duty nonwoven or film applications are typically titanium, which has excellent fatigue resistance, but poor thermal diffusivity. Unsatisfactory results, including rips, tears, and holes in bonded or formed substrates have limited the applicability of ultrasonic bonding and forming processes at the high throughputs and line speeds required in the absorbent article industry, and other industries. A need, therefore, exists for methods and devices useful for ultrasonic forming and bonding of substrates in the absorbent article industry, and other industries. SUMMARY Various embodiments solve the above-mentioned problems and provide methods and devices useful for ultrasonic forming and bonding of substrates in the absorbent article industry. More specifically, various embodiments relate to a method of manufacturing portions of absorbent articles. The method may comprise conveying a substrate through a nip formed between a first device and a second device, transmitting vibrational energy from the second