Dryer sheet process

Details Dryer sheet process Dryer sheet process

2001-08-29

2002-08-20

Hardee, John (Department: 1751)

Cleaning compositions for solid surfaces, auxiliary compositions

Auxiliary compositions for cleaning, or processes of preparing

Textile softening or antistatic composition

C510S101000

Reexamination Certificate

active

06436895

ABSTRACT:

BACKGROUND
A well known commercial product in the laundry care industry is the fabric dryer sheet. In use, the consumer typically uses at least one sheet in the drying cycle of the laundering process. The sheets generally include a substrate material, such as a web, wherein the substrate carries one or more ingredients to impart desired benefits to the clothing. These ingredients can include, for example, perfumes, anti-static agents, dye transfer inhibitors, whitening agents, enzymes, stain repellents and wrinkle reducing agents.
Processes for fabricating these dryer sheets are also well known. In a typical process, a large role of the web material is guided at high speeds through various coating, smoothing and drying/cooling steps wherein one or more ingredients are applied to the web. An example of this process is shown in FIG.
1
.
With reference to
FIG. 1
, web
5
is preferably a polyester material and provided in rolls
2
. Rolls
2
are typically about 37 inches to about 85 inches in width and have a length between about 8,000 and about 13,000 yards. Web
5
passes through various rollers and rods wherein ingredients are applied to the web. As shown, web
5
is passed over guide roll
12
and onto applicator roll
14
. Applicator roll
14
transfers ingredients
17
from coating pan
15
onto the web. A holding tank (not shown) can be used to supply the ingredients to coating pan
15
. Preferably, automatic controls are used to ensure a proper level and temperature of ingredients
17
in pan
15
.
As known in the art, ingredients
17
can include perfume material in addition to other fabric treatment agents, particularly those that provide anti-static and fabric softening benefits. These fabric treatment agents can include, for example: cationic compounds, such as quaternary ammonium compounds; nonionic surfactants, such as ethoxylated alcohols; fatty alcohols; fatty acids; alkali metal soaps of fatty acids; carboxylic acids and salts thereof; fatty acid esters; glycerides; waxes; anionic surfactants; water; optical brighteners; fluorescent agents; antioxidants; colorants; germacides; perfumes; bacteriocides; enzymes; dye transfer inhibitors; soil release polymers; skin care benefit agents; perfume carriers (e.g. starch, clyclodextrins); wrinkle reducing agents; and the like. Various preferred non-cationic formulations are disclosed in U.S. patent application Ser. No. 08/832,887, filed Apr. 4, 1997, the contents of which is incorporated by reference. In prior art processes, perfume has been present from about 2 wt % to about 6 wt % based on total ingredients
17
.
In a preferred embodiment, the ingredients are maintained at approximately 140-190° F. in both the holding tank and coating pan
15
. At this temperature, one or more ingredients can be lost to the atmosphere due to their volatility or be adversely affected by means of thermal degradation. When the perfume is present, it is estimated that there is a loss of approximately 15 wt. % of the perfume to the atmosphere at this coating step.
Further on in the process of
FIG. 1
, after coated in the coating pan, coated web
5
′ passes over smoothing rod
18
to guide roll
20
. From guide roll
20
, the web passes to heating drum
22
, travels to cooling drums
24
and
26
, which are preferably cooled to below about 100° F. by chilled water. Cooled web
5
′ then passes to trimming station
28
, wherein the web is rolled and preferably cut into roles
2
′. Roles
2
′ are preferably about 12 inches in width. At this point in the process, the roles can be stored for later cutting and packaging. During the process shown in FIG.
1
. the web can travel as fast as 1,000 feet per minute. It is estimated that the additional perfume lost after the step of coating can be in the range of approximately 20 wt. % to 30 wt. % from that which was originally present in pan
15
.
Turning to
FIG. 2
, final processing of coated web
5
′ is carried out by passing one or more of the coated roles
2
′ through a series of guide rollers
32
. The web is then folded by folders
34
, passed to conveyor
36
and cut by knife
38
. After cutting, the folded sheets are tamped down, stacked and accumulated for packaging.
During the above-described processes, it has been found that a significant amount of volatile agents can be lost prior to final packaging, particularly perfumes. This is generally due to the relatively high volatility of most perfume agents. For example, it has been found that up to 45% of the perfume added in a typical process can be lost by the time the dryer sheet is folded and packaged.
Therefore, there is a need for an improved fabric dryer sheet manufacturing process wherein the loss of volatile agents during the process of making the fabric sheets is minimized.
Perfume agents can be classified by their relative volatility. High volatile perfumes are known as “high notes” while relatively unvolatile perfumes are known as “low notes”. Due to their high volatility, high note perfumes are typically more perceptible by humans than low note perfumes. High note perfumes also have a wider range of odors and, therefore, allow for greater flexibility when selecting perfume agents. Unfortunately, when manufacturing dryer sheets, it is the desired high notes that can be lost during processing. This has resulted in a decreased amount of high note perfumes making it into the packaged product and alteration of the perfume profile. Use of high note perfumes have also been reduced or eliminated from perfume formulations due to the above-described process conditions.
Therefore, there is also a need for fabric sheet manufacturing techniques that would allow for increased usage of high note perfumes, wherein the highly volatile perfumes are retained on the fabric sheet so as to reach the consumer.
SUMMARY
For simplicity, “perfume” will be used herein to describe a fabric treatment agent that can volatilize or degrade from heat in an undesirable manner. It is within the scope of the present disclosure, however, that other volatile agents or heat sensitive agents can be advantageously applied by the presently disclosed process.
The present disclosure relates to a process that minimizes the loss of perfume and other volatile agents during the fabrication of dryer sheets. It has been found that it is possible to de-couple the addition of volatile or heat sensitive agents from one or more of the manufacturing process steps, particularly those portions that run at a high speed and/or high temperature.
In one preferred embodiment, the a selected agent or agents are applied during high speed web movement after high temperature application of other ingredients. In a second preferred embodiment, the selected agent or agents can be applied just prior to folding and packaging.
It has been found, for example, that by adding the perfume or other volatile agents closer to the step of packaging, i.e. after application of other ingredients in coating pan
15
, there is less loss of ingredients to the atmosphere during the dryer sheet process. In the case of perfumes, this new process has less affect on the perfume profile and, therefore, a wider variety of perfumes can be used. In addition, because ingredients are no longer lost or lost to a lesser extent, less of the ingredient is needed when practicing the present disclosure, resulting in raw material cost savings.


REFERENCES:
patent: 3632396 (1972-01-01), Perez-Zamora
patent: 4073996 (1978-02-01), Bedenk et al.
patent: 4619779 (1986-10-01), Hardy

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