WO2009121831A1

WO2009121831A1 - Controlled release particles

Info

Publication number: WO2009121831A1
Application number: PCT/EP2009/053731
Authority: WO
Inventors: Joseph Steven Maxim, Jr.; Martin Crossman; Paul Michael Ferm
Original assignee: Akzo Nobel N.V.
Priority date: 2008-04-01
Filing date: 2009-03-30
Publication date: 2009-10-08

Abstract

Aqueous controlled release formulation containing formaldehyde-free water- insoluble particles having a solid core of a synthetic solvent free polymer containing a plasticizer and a hydrophobic volatile liquid such as a fragrance or perfume and using another polymer to suspend or disperse the solid core in the aqueous formulation. These aqueous controlled release formulations include personal care formulations such as washing and hair-conditioning compositions, laundry detergent compositions and rinse conditioner compositions for fabric softening.

Description

CONTROLLED RELEASE PARTICLES

BACKGROUND OF THE INVENTION

Technical Field. This invention relates to aqueous, controlled release formulations such as personal care and laundry compositions. More particularly, this invention is directed towards solid particles for providing controlled/extended release of volatile liquids (e.g., fragrance) in an aqueous environment.

Background Information. Use of perfume in, for example, laundry detergents has been a signature of formulators for years. Still, the creativity and flexibility of formulators and perfumers has been limited by the volatility of the fragrance. In powdered products, this can be solved by encapsulating fragrance or perfume components in a water soluble shell such as starch, whereby the shell dissolves upon addition to an aqueous environment, releasing the fragrance. Unfortunately, this encapsulation approach is not applicable to compositions in the form of an aqueous formulation, such as liquid laundry detergents or fabric softeners, as the water soluble shell dissolves in the aqueous medium of the formulation.

One approach to liquid-based formulations is to encapsulate the fragrance in a water insoluble shell, for example, formaldehyde-based shell. These shells survive the detergent environment and are deposited onto the fabric during the wash cycle. However, they then require mechanical breaking by the consumer to release the encapsulated fragrance. The problem with this approach is that formaldehyde has a bad toxicological profile and is not suitable for consumer applications.

Accordingly, there is still a strong industry wide need for particles that do not significantly increase the viscosity of a detergent, be easy and inexpensive to manufacture and provide long lasting fragrance to clothing being washed. Furthermore, these particles should be capable of holding a higher loading of volatile liquids within the aqueous formulation, for example, liquid laundry detergents.

SUMMARY OF THE INVENTION The current invention relates to aqueous controlled release formulations containing formaldehyde-free water-insoluble particles. The particles include a solid core of a solvent free synthetic polymer containing a plasticizer and a volatile hydrophobic liquid (such as a perfume or fragrance). The particles further include a second, water soluble polymer present as a film or coating on the outside of the particle for aiding in suspending or dispersing the core in the aqueous formulation.

DETAILED DESCRIPTION

It has now found that loading, retention and controlled release of volatile liquids from solid particles can be improved by producing a solid core of a first synthetic polymer containing a plasticizer, and using a second water soluble polymer coating to suspend or disperse the solid core.

For the purpose of this invention, a "plasticizer" is defined as any material that lowers the glass transition temperature of the particles by about 10°F (about 5.5°C) or more. Examples of such plasticizers include citrates, phthalate esters, benzoates, alkylcitrates, and other appropriate molecules of relatively small molecular weight.

The plasticizer can be added at addition levels of about 0.1% to about 10%, based on total weight of the particles. In one embodiment the plasticizer is added at about 1 % to about 5%, based on total weight of the particles.

Residual monomers can also plasticize these water insoluble particles. However, high levels of residual monomer (e.g., greater than 1000 ppm) have unfavorable toxicological profiles and therefore are not preferred. As such, it is preferred that the level of residual monomers be less than about 100 ppm.

Particles according to the present invention are insoluble in water, thereby enabling them to be deposited onto fabric from an aqueous wash or rinse liquor.

Median size of the particles can range from about 1 to about 300 urn. In one embodiment the particle size can be from about 10 to about 100 urn. In another embodiment the particle size can be from about 30 to about 80 urn. One skilled in the art will realize that particle size can impact deposition efficiency and visual impact of the particle on product appearance.

The water insoluble particulate according to the present invention is made up of a solid core comprising a first polymer. In one aspect, this polymer is a solvent free synthetic polymer. For the purpose of this invention, "synthetic" refers to polymers produced by polymerizing vinyl monomers. Examples of suitable vinyl monomers include isobutyl methacrylate, n-butyl acrylate, n-butyl methacrylate, isobutyl acrylate, n-propyl acrylate, iso-propyl methacrylate, vinyl acetate and styrene. Monomers can also include those containing anionic or cationic substituents. Cationic substituents, for instance, can help compatibilize the resulting monomer with other formulations and can also ultimately help in the deposition of the resulting particles to various surfaces. One such embodiment the cationic monomer is acryloxyethyldimethylbenzyl ammonium chloride. In one embodiment the vinyl monomers polymerized are isobutyl methacrylate, styrene and combinations of these monomers with each other as well as with ionic monomers.

In one embodiment the first polymer is cross-linked. Preferably, the polymer is crosslinked when forming the core as this increases the insolubility of the particles. Crosslinkers are selected from a broad class of materials and include di, tri and tetra functional vinyl compounds. In one aspect, useful crosslinkers include divinyl styrene, ethylene glycol dimethacrylate and butane diol diacrylate. Typically addition levels from about 0.01 to about 2 wt%, based on total weight of the polymerization mixture, can be used for these crosslinkers. In one embodiment the crosslinker(s) is present from about 0.1 to about 1 wt% of the total polymerization mixture weight.

For purposes of this invention, "solvent free" means that the polymer is produced in aqueous media in the absence of any solvents.

Polymerization can be initiated using a free radical source such as an azo compound or organic peroxide. In one embodiment tert-butylperoxy-2- ethylhexanoate (Esperox 28) and tert-amylperoxy-2-ethylhexyl carbonate (TAEC) are used and are added at levels of about 0.1 % to about 2 wt% of the total polymerization mixture weight.

Water insoluble particles according to the present invention are formaldehyde-free due to growing toxicity and environmental concerns connected with the use of formaldehyde. Hence, the presence of formaldehyde is detreminetal in consumer products. For purposes of this invention, "formaldehyde-free" means that the water- soluble particles are produced by materials and processes in which formaldehyde is not deliberately added in.

The second polymer utilized in particles according to the present invention can be used to disperse and/or suspend the particles in the aqueous media. Non-limiting examples of such polymers include cellulosics, vinylic, allylic, or acrylic polymers. The polymers are selected for their colloidal stabilization properties and useful materials include modified cellulose polymers, polyvinyl alcohols, and poly vinyl pyrrolidone. Molecular weight and chemical modifications of the polymers are chosen so as to optimize their stabilization properties. In one embodiment the second polymer is polyvinyl pyrrolidone having an average molecular weight of 1 ,500,000.

The second polymer typically forms a film or coating on the particle. This coating can be as thin as a monolayer of atoms, or up to about a micron in thickness. The coating prevents the droplets from coalescing until after the polymerization is complete and acts as a dispersant to keep the particles in suspension. It may be possible to remove this coating after polymerization, yet it will have little effect on the function of the particles and their ability to deliver a fragrance.

In one embodiment the second polymer is able to disperse the particles. In the dispersion process, it may be necessary to increase the viscosity of the continuous phase by utilizing a member of a broad class of small- and high-molecular weight viscosity modifiers. One such example of a viscosity modifier is maltose, and does not interfere with polymerization and cross-linking. These viscosity modifiers are added in the range of from about 1 to about 50 weight percent of the weight of the particle. In one embodiment maltose is added in the range of from about 10 to about 40 weight percent of the weight of the particle.

For purposes of this invention, a "volatile liquid" is defined as any organic or inorganic liquid, such as an oil, with a boiling point of less than about 300°C. In an embodiment, the boiling point of the volatile liquid will be less than about 200⁰C. In another embodiment, the boiling point of the volatile liquid will be less than about 150⁰C.

The hydrophobic volatile liquid incorporated in the first polymer is typically a fragrance. The weight percent of the fragrance in these particles are in a range of from about 1 to about 50 weight percent, based on total weight of the particle. In another embodiment of this invention the fragrance is present in the particle in an amount of from about 5 to about 25 weight percent, based on total weight of the particle. The fragrance may be any volatile material used to provide a function. Some non-limiting examples of fragrances are insecticides, pheromones, perfumes, deodorants, musks, flavors and scents.

Particles of this invention may be incorporated into an aqueous controlled release formulation such as a detergent composition for fabric washing. Such a formulation composition may be obtained from a solid form, such as from a laundry tablet or compressed solid composition, or may be provided in liquid form.

Particles of this invention may also be used in any other application wherein an aqueous suspension or solution is encountered and the deposition of long lasting fragrance is desired. Non-limiting examples of these applications include hair shampoo and conditioner, fabric softeners, body wash, hand soap, carpet shampoo, pet care products, and laundry detergents.

The following examples are presented to further illustrate and explain the present invention and should not be taken as limiting in any regard.

EXAMPLE 1 -

An aqueous suspension polymer was made according to the following procedure: 100 grams of water, 4 grams of PVP K-90 (ISP Corporation), and 160 grams of Satin Sweet 65% (Cargill) were added to a 1 -liter, 4-neck, round-bottom flask fitted with a condenser, thermocouple and half moon agitator. The agitator was turned on. In a separated beaker were mixed 170 grams of styrene (West Lake), 3.45 grams of ADAM Quat BZ-80 (Arkema), 0.875 grams of Sipomer SR-213 (Sartomer), and 4.35 grams of Citroflex 4 (Morflex). This mixture was added to the reactor with constant mixing. After complete mixing, a further mixture of 5.2 grams of Esperox 28 (Crompton) and 2.6 grams of tertamylperoxy-2-efhylhexyl carbonate 92% (Aldrich Chemical) was added to the reactor and allowed to mix for one hour. This total mixture was heated to 74°C and held for 6 hours. After the 6 hour hold at 74°C, 100 grams of water was added and the reactor contents were heated to a temperature of 92-100°C for an additional 6 hours. After the second 6-hour period, the reactor contents were cooled to 30°C. The reactor contents were then transferred to a storage container.

The final percentage content of Examples 1 and 2 on a weight basis is shown in Table 1 below.

COMPARATIVE EXAMPLE 2 -

An aqueous suspension polymer was made with the following procedure: 100 grains of water, 4 grams of PVP K-90 (ISP Corporation), and 160 grams of Satin Sweet 65% (Cargil) were added to a 1 - liter, 4-neck, round-bottom flask fitted with a condenser, thermocouple and half moon agitator. The agitator was turned on. In a separated beaker were mixed 170 grams of styrene (West Lake), 3.45 grams of ADAM Quat BZ-80 (Arkema), and 0.875 grams of Sipomer SR-213 (Sartomer). This mixture was added to the reactor with constant mixing. After complete mixing, a further mixture of 5.2 grams of Esperox 28 (Crompton) and 2.6 grams of tertamylperoxy-2-ethylhexyl carbonate 92% (Aldrich Chemical) was added to the reactor and allowed to mix for one hour. This total mixture was heated to 74°C and held for 6 hours. After the 6 hour hold at 74°C, 100 grams of water was added and the reactor contents were heated to a temperature of 92-100⁰C for an additional 6 hours. After the second 6-hour period, the reactor contents were cooled to 30°C. The reactor contents were then transferred to a storage container.

The final percentage content of Examples 1 and 2 on a weight basis is shown in Table 1 below. EXAMPLE 3 -

An aqueous suspension polymer was made with the following procedure: 260.55 grams of water and 4 grams of PVP K-90 (ISP Corporation) were added to a one liter , 4-neck, round-bottom flask fitted with a condenser, thermocouple and half moon agitator. The agitator was turned on. In a separated beaker were mixed 170 grams of styrene (West Lake), 3.45 grams of ADAM Quat BZ-80 (Arkema), 0.875 grams of Sipomer SR-213 (Sartomer), and 4.35 grams of Citroflex 4 (Morflex). This mixture was added to the reactor with constant mixing. After complete mixing, a further mixture of 5.2 grams of Esperox 28 (Crompton) and 2.6 grams of tertamylperoxy-2-ethylhexyl carbonate 92% (Aldrich Chemical) was added to the reactor and allowed to mix for one hour. This total mixture was heated to 74°C and held for 6 hours. After the 6 hour hold at 74°C, 100 grams of water was added and the reactor contents were heated to a temperature of 92-100°C for an additional 6 hours. After the second 6-hour period, the reactor contents were cooled to 30°C. The reactor contents were then transferred to a storage container.

The final content of Examples 1 , 2, and 3 on a weight percent basis is shown in Table 1 below.

Table 1 - Polymer Content

EXAMPLE 4 -

Samples from Examples 1 , 2, and 3 were tested in the following manner to determine their size, their glass transition temperature, and their ability to absorb fragrance oil. For initial particle size measurements, the samples were thoroughly mixed and diluted for test with a Beckman-Coulter LS 13 320 particle size analyzer.

Several different size parameters were noted, most important was the D10, D50, and D90 sizes which correlated to the 10^th, 50^th, and 90^th percentile sized particles. In addition, the mode or most prevalent particle size was noted.

To determine the glass transition temperature, T₉, the samples were washed in water and filtered dry to remove both the maltose viscosity modifier contained in Example 1 and to remove any excess moisture contained in either sample. Example 1 made with plasticizer and Comparative Example 2 made without plasticizer were analyzed in a TA Instruments Model DSC 2920 differential scanning calorimeter. The results are shown in the table below.

The results showed that the T₉ of Example 1 was reduced by 14.5°C relative to Comparative Example 2.

Table 2 - Glass Transition Temperature

The samples were then loaded with fragrance. Two different fragrance loadings were analyzed to check for the fragrance holding capacity of the particles. The fragrance loadings were 50% and 100% relative to the polymer content. After equilibration for 1-5 days, the final particle size was again measured. For this analysis, the mode of the particle size distribution was found, which represents the most prevalent particle size and from this diameter the volume of the particle was calculated. In this way, the swelling of the particle relative to the amount of fragrance oil added to the mixture was determined. This data is shown in the table below. The data shows that the volume of the mode particle of Example 1 , increased to levels which imply full incorporation of fragrance. For instance, when the targeted particle swelling increase of 100% was targeted, a value of 114%) swelling was determined. For Comparative Example 2, the volume of the mode particle increased to levels which imply only partial incorporation of fragrance. For example when the targeted particle swelling increase of 100% was targeted, a value of only 76% was determined.

Table 3 - Fragrance Holding Capacity

EXAMPLE 5 -

An aqueous control release formulation was created using the following procedure. Example 1 was mixed with a multi-component fragrance composition suitable for laundry treatment. The ratio of polymer particle to fragrance was 1 :1. The fragrance and Example 1 were mixed thoroughly by hand and then rolled for 2 hours. The sample was then allow to rest for 2 days and evaluated to ensure the fragrance and polymer was fully compatibilized. The fragrance-polymer mixture was added to a typical commercial liquid fabric conditioner which contained no fragrance. The weight of the fabric conditioner unit dose is 30 g and the weight of the polymer- fragrance slurry was calculated to include 1% fragrance to the fabric conditioner, therefore 2 g of the slurry was added which corresponded to 0.3 g of fragrance and 0.3 g of Example 1 polymer. The resulting fabric conditioner mixture was mixed by hand, rolled for 2 hours, and then aged at room temperature for seven days.

COMPARATIVE EXAMPLE 6 -

A comparative aqueous control release formulation was created using the following procedure. Comparative Example 2 was mixed with the same multi-component fragrance composition. The ratio of polymer particles to fragrance was 1 :1. The fragrance and Comparative Example 2 were mixed thoroughly by hand and then rolled for 2 hours. The sample was then allow to rest for 2 days. 2 g of polymer- fragrance slurry, containing 0.3-g fragrance was then added to 30-g fabric conditioner base, mixed by hand, rolled for 2 hours, and then aged at room temperature for seven days. COMPARATIVE EXAMPLE 7 -

A comparative aqueous control release formulation was created using the following procedure. This was a comparative example to Examples 5 and 6 and contained only neat fragrance oil and no polymer. 0.3 g of fragrance was added to 30-g fabric conditioner base, mixed by hand, rolled for 2 hours, and then aged at room temperature for seven days.

EXAMPLE 8 -

A laundry experiment was carried out using standard procedures. Fabric conditioner samples containing fragrance-polymer mixtures (Example 5 and Comparative Example 6) were directly to the neat fragrance control sample (Comparative Example 7).

A fixed protocol was used to launder, dry, and evaluate the samples. This included using 6 pounds of mixed cloth, including terry washcloths, towels, and pillow cases. The washcloths were used for sensory evaluation and the remaining cloth was used as a ballast to ensure the samples were distributed among a typical full load of clothes.

The triangle test showed a statistically significant difference between Example 5 and Comparative Example 7. In particular, 8 of 8 panelists picked out the odd samples in the balanced triangle test; therefore the triangle test concludes that the samples were different with 100% confidence. The panel was then asked to do an olfactory intensity rating of the same samples on a 0-5 scale, where the rating definitions were 0 = no detectable fragrance, 1 = detectable, 2 = light odor, 3 = medium odor, 4 = strong odor, and 5 = very strong odor intensity, It was found that Example 5 had a average rating of 2 whereas Comparative Example 7 had an average rating of 0.5, further showing that inventive Example 5, created with Example 1 polymer, gave a strong positive olfactory intensity response. A further triangle sensory test was performed on Comparative Example 6 and Comparative Example 7. Here the olfactory triangle test data showed that only 5 of 8 respondents could correctly identify the odd sample. This does not satisfy the 95% confidence limit criteria for distinguishing samples and it was therefore concluded that the samples were not significantly different. In particular this sensory test demonstrated that Comparative Example 2, when mixed with fragrance, formulated with fabric conditioner and then used to treat laundry, did not give a statistically significant difference in fragrance perception ten days after the laundry process when compared to clothes treated with neat fragrance oil in fabric conditioner.

Although the present invention has been described and illustrated in detail, it is to be understood that the same is by way of illustration and example only, and is not to be taken as a limitation. The spirit and scope of the present invention are to be limited only by the terms of any claims presented hereafter.

Claims

CLAIMS:

1. Water insoluble particle comprising a solvent-free first polymer core and a water soluble second polymer coating surrounding the first polymer core, the first polymer core further comprising a plasticizer and a hydrophobic volatile liquid, wherein the insoluble particle has an overall particle size of from about

1 to about 300 microns.

2. Particle of claim 1 wherein the first polymer core is isobutyl methacrylate, polystyrene or combinations thereof.

3. Particle of claim 1 or 2 wherein the second polymer coating is PVP.

4. Particle of any one of claims 1-3 wherein the particle size is from about 10 to about 100 microns.

5. Particle of claim 4 wherein the particle size is from about 30 to about 80 microns.

6. Particle of any one of the preceding claims wherein the plasticizer is selected from the group consisting of citrates, phthalate esters, benzoates, alkyl citrates and combinations thereof.

7. Particle of any one of the preceding claims wherein the plasticizer is present in an amount of from about 0.1 to about 10% by weight, based on weight of the particle.

8. Particle of claim 7 wherein the plasticizer is present in an amount of from about 1.0 to about 5.0% by weight, based on weight of the particle.

9. Particle of any one of the preceding claims wherein the first polymer is crosslinked.

10. Liquid composition comprising water insoluble particles according to any one of the preceding claims.

11. The liquid composition of claim 10 wherein the particles provide long lasting delivery of the volatile liquid.

12. The liquid composition of claim 10 or 11 wherein the composition is selected from the group consisting of laundry detergents, fabric softeners, shampoos, hair conditioners and body washes.