Foamable powder-based compositions and methods of foaming the same

Abstract

Described herein are foamable powder-based compositions comprising: (a) at least one powder-based polymer in an amount no less than 8 wt% based on the total weight of the composition, (b) at least one plurality of expandable microspheres in an amount no less than 15 wt% based on the total weight of the composition, and (c) optionally at least one filler, wherein the plurality of expandable microspheres in the composition expand upon heating; and wherein the composition has a water content no more than 3 wt% based on the total weight of the composition.

Description

Technical Field

[0001] This invention relates to a foamable powder-based composition and a foaming method thereof. In particular, this invention relates to a foamable powder-based composition capable of withstanding long-term storage and transportation at high temperatures, and a foaming method thereof. Background Technology

[0002] Compared to traditional closed-cell extruded polystyrene foam packaging, more environmentally friendly single-use food packaging and containers are gaining popularity. Packaging made entirely of plastic typically does not biodegrade within 400 years, or even at all, and some regulations have already banned its use.

[0003] There is a need for recyclable, biodegradable, and / or compostable alternative packaging. One such package comprises a cellulose-based substrate derived from renewable materials that can be recycled and / or composted. The package is made by joining two cellulose substrates, with an air gap inserted between them. Some disadvantages of these alternative packages include lower insulation and poorer structural integrity compared to plastic packaging. When the package is handled and bent, the air gap between the two substrates becomes compressed, and insulation decreases in those compressed areas. Insulation can be improved by increasing the air gap between the cellulose substrate layers, increasing the thickness of the cellulose substrate, or inserting a cellulose medium between the two layers.

[0004] Some of the improved packaging described above is described in US 9,580,629 B2, US 8,747,603 B2, US 9,273,230 B2, US 9,657,200 B2, US20140087109 A1, US20170130399 A1, US20170130058 A1, and US20160263876 A1. The packaging forms air gaps in the coating / adhesive / expandable composition sandwiched between two substrates, which provides insulation. However, if the substrate thickness exceeds 1.5 inches, these packages may result in uneven insulation. WO 2019 / 018523A1 discloses an improved foaming method that achieves uniform insulation for packages of different sizes by exposing the expandable composition to dielectric heating. All of the aforementioned coatings / adhesives / foamable compositions are water-based or emulsion-based. While they impart improved insulation properties to packaging, water-based or emulsion-based compositions have limited shelf life and are not convenient for transportation, especially in summer when temperatures exceed 35°C. This is because liquid-based compositions may foam and eventually lead to phase separation at high temperatures. Furthermore, compared to conventional products, the lower weight and volume of these compositions reduce transportation costs.

[0005] There is a need in the art for a foamable composition and foaming method that can withstand long-term storage and transportation at high temperatures while achieving improved foamable properties, thereby providing insulation in the manufacture of articles. Summary of the Invention

[0006] One embodiment disclosed herein is a foamable powder-based composition comprising:

[0007] (a) at least one powder-based polymer, the amount of which is not less than 8% by weight based on the total weight of the composition.

[0008] (b) at least one plurality of expandable microspheres, the amount of which is not less than 15% by weight based on the total weight of the composition, and

[0009] (c) Any one of the fillers that is present may be selected.

[0010] The plurality of expandable microspheres in the composition expand upon heating; and

[0011] The composition has a water content of no more than 3% by weight, based on the total weight of the composition.

[0012] Another embodiment relates to a foaming method, which includes the following steps:

[0013] (i) A powder mixture comprising: (a) a powder-based polymer in an amount of not less than 8% by weight based on the total weight of the powder mixture; (b) a plurality of expandable microspheres in an amount of not less than 15% by weight based on the total weight of the powder mixture; (c) a filler optionally present; and (d) an additive optionally present, wherein the powder mixture has a water content of not more than 3% by weight based on the total weight of the powder mixture.

[0014] (ii) Add water to the powder mixture obtained in step (i) and mix to form a composition dispersion, wherein the composition dispersion has a solids content greater than 58%; and

[0015] (iii) Expose the dispersion of the composition to conventional or dielectric heating or a combination thereof.

[0016] Another embodiment relates to a method for forming an article, which includes the following steps:

[0017] A method for forming an article of articles, comprising the following steps:

[0018] (i) A powder mixture comprising: (a) a powder-based polymer in an amount of not less than 8% by weight based on the total weight of the powder mixture; (b) a plurality of expandable microspheres in an amount of not less than 15% by weight based on the total weight of the powder mixture; (c) a filler optionally present; and (d) an additive optionally present, wherein the powder mixture has a water content of not more than 3% by weight based on the total weight of the powder mixture.

[0019] (ii) Add water to the powder mixture obtained in step (i) and mix to form a composition dispersion, wherein the composition dispersion has a solids content of more than 58%;

[0020] (iii) Apply the dispersion of the composition to a first substrate;

[0021] (iv) Applying a second substrate to the composition dispersion to form an article, wherein the composition dispersion is sandwiched between the two substrates; and

[0022] (v) Apply conventional or dielectric heating, or a combination thereof, to the article.

[0023] The other features and aspects of the topic will be described in more detail below. Attached Figure Description

[0024] Figure 1 A photograph of the composition of Example 1, which was activated by microwave heating immediately after the microspheres expanded, is shown.

[0025] Figure 2 A photograph of the composition of Example 3, which was activated by microwave heating immediately after the microspheres expanded, is shown.

[0026] Figure 3 A photograph of the composition of Comparative Example 1, which was activated by microwave heating immediately after the microspheres expanded, is shown.

[0027] Figure 4 A photograph of the composition of Comparative Example 2, which was activated by microwave heating immediately after the microspheres expanded, is shown.

[0028] Figure 5 A photograph of the composition of Comparative Example 3, which was activated by microwave heating immediately after the microspheres expanded, is shown.

[0029] Figure 6 A photograph of the composition of Comparative Example 4, which was activated by microwave heating immediately after the microspheres expanded, is shown. Detailed Implementation

[0030] Those skilled in the art will understand that this discussion is merely a description of exemplary embodiments and is not intended to limit the broader aspects of the invention.

[0031] Unless otherwise stated, the terminology used in the context of this invention shall be interpreted according to the following definitions.

[0032] Unless otherwise stated, as used herein, the terms “a,” “an,” “the,” and “the” include both singular and plural references.

[0033] The term “comprising” as used herein is synonymous with “including” or “containing”, and is inclusive or open-ended and does not exclude additional unlisted members, elements or method steps.

[0034] The terms “at least one” or “one or more” used in this article to define components refer to the type of components, not the absolute number of molecules.

[0035] Unless otherwise stated, the term “about” as used herein with respect to numerical values ​​means the numerical value ± 10% of the value, preferably ± 5% of the value. For example, “about 20% by weight” thus refers to 20 ± 2% by weight, preferably 20 ± 1% by weight.

[0036] Unless otherwise specified, the enumeration of numerical endpoints includes all numbers and fractions that fall within the corresponding range, as well as the enumerated endpoints.

[0037] Unless otherwise defined, all terms used in this invention (including technical and scientific terms) shall have the meanings commonly understood by one of ordinary skill in the art to which this invention pertains.

[0038] According to a first aspect of the present invention, the present invention provides a foamable powder-based composition comprising:

[0039] (a) at least one powder-based polymer, the amount of which is not less than 8% by weight based on the total weight of the composition.

[0040] (b) at least one plurality of expandable microspheres, the amount of which is not less than 15% by weight based on the total weight of the composition, and

[0041] (c) Any one of the fillers that is present may be selected.

[0042] The plurality of expandable microspheres in the composition expand upon heating, and the composition has a water content of no more than 3% by weight based on the total weight of the composition.

[0043] (a) Powder-based polymers

[0044] According to the present invention, based on the total weight of the composition, the foamable powder-based composition contains not less than 8% by weight of at least one powder-based polymer.

[0045] Powder-based polymers may include any desired polymer components, including vinyl acetate homopolymers, copolymers prepared from vinyl acetate and at least one other monomer, copolymers prepared from vinyl chloride and at least one other monomer, and mixtures thereof. Particularly preferred powder-based polymers may be copolymers prepared from vinyl acetate and at least one other monomer (e.g., ethylene).

[0046] The powder-based polymer used as component (a) can be prepared by spray-drying a polymer dispersion. When the powder-based polymer comes into contact with water, the dispersible polymer powder particles disintegrate and release individual dispersion particles again. The dispersed polymer powder has the same properties as the original dispersion.

[0047] Available powder-based polymers are commercially available under various trade names, including, for example, VINNAPAS from Wacker. TM 5044N, 5043N, 4121N, 4042H and 5048H.

[0048] Particularly preferably, the powder-based polymer may be present in an amount of 10% to 50% by weight, more preferably 10% to 40% by weight, based on the total weight of the composition.

[0049] (b) Expandable microspheres

[0050] According to the present invention, based on the total weight of the composition, the foamable powder-based composition comprises not less than 15% by weight of at least one plurality of expandable microspheres, wherein the plurality of expandable microspheres in the composition expand upon heating.

[0051] The expandable microspheres suitable for use in this invention can expand in size in the presence of heat. Expandable microspheres that can be used in this invention include, for example, thermally expandable polymer microspheres, including those having a hydrocarbon core and a polyacrylonitrile shell (e.g., under the trade name DUALITE). TM Those that are sold) and other similar microspheres (e.g., those marketed under the trade name EXPANCEL) TM (Those for sale). Expandable microspheres can have any unexpanded size, including diameters from about 5 micrometers to about 30 micrometers. In the presence of heat, the diameter of the expandable microspheres of the present invention can increase to about 3 to about 10 times the original size. When the microspheres in the composition expand, the composition becomes a foam-like material with improved insulation properties. The microspheres are typically made of a plastic or polymer shell, and a foaming agent is inside the shell, which is designed to be activated upon reaching a specific temperature.

[0052] Expandable microspheres have a specific temperature at which they begin to expand and a second temperature at which they reach maximum expansion. Microsphere grades are typically sold with a specific expansion temperature (Texp) and a maximum expansion temperature (Tmax). The initial expansion temperature (Texp) is the typical temperature at which the microspheres begin to expand, and the maximum expansion temperature (Tmax) is the temperature at which approximately 80% of the microspheres have expanded. If the microspheres are exposed to temperatures much higher than Tmax, they will begin to explode and release gas.

[0053] A particularly suitable microsphere has a Texp of 80°C to 105°C. The temperature at which the microsphere reaches maximum expansion (Tmax) is ideally 90°C to 135°C.

[0054] In a preferred embodiment, it is desirable that the density of the expandable microspheres is less than 10 kg / m³. 3 .

[0055] Depending on the amount of microspheres and the type of polymer, foamable powder-based compositions can have binder properties. High levels of microspheres will result in lower or no binder properties, while low levels (less than about 30% by weight based on the total weight of the composition) will result in binder properties of the composition.

[0056] The amount of expandable microspheres in the composition can be adjusted depending on the fully expanded size of the microspheres. The desired amount of microspheres in the composition can be varied depending on the specific expandable microspheres used.

[0057] Component (b) further enhances the structural integrity of the composition after expansion. While introducing voids into the matrix typically reduces mechanical integrity, component (b) in the composition provides rigidity when applied to the substrate. This is particularly useful for packaging fragile contents.

[0058] In another embodiment, component (b) may be pre-expanded. In yet another embodiment, the microspheres may be a mixture of pre-expanded microspheres and expandable microspheres.

[0059] Commercially available products can be used in this invention. Examples include Expansion, which is available from Nouryon. TM 031WUF 40 and F-SF 36 available from Matsumoto.

[0060] In a preferred embodiment, based on the total weight of the composition, the expandable microspheres may be present in the composition in an amount of not less than 20% to 70% by weight, more preferably not less than 20% to 50% by weight. The expansion ratio of the expandable microspheres and the loading level of the microspheres will be related to each other.

[0061] (c) Packing

[0062] According to the present invention, the foamable powder-based composition may optionally contain at least one filler.

[0063] Exemplary fillers include corn starch, pearl starch, physically modified starch, chemically modified starch, dextrin, and mixtures thereof, preferably a mixture of corn starch and dextrin. During foaming, dextrin can provide viscosity to the composition dispersion upon the addition of water.

[0064] Commercially available products can be used in this invention. Examples include corn starch available from Cargill and dextrin from Tianzhu Chemical.

[0065] Particularly preferably, the filler may be present in an amount of 0% to 70% by weight, and more preferably 10% to 60% by weight, based on the total weight of the composition.

[0066] (d) Additives

[0067] The composition optionally further comprises (d) at least one additive selected from plasticizers, pigments, dyes, stabilizers, anti-caking agents, dispersants, polyvalent water-soluble salt accelerators, and mixtures thereof. These components may be included in an amount from 0 to 15% by weight, based on the total weight of the composition.

[0068] An example plasticizer is that which can be used as BENZOFLEX TM The obtained benzoic acid esters include diethylene glycol dibenzoate, dipropylene glycol dibenzoate, etc.

[0069] Exemplary anti-caking agents include aluminum, silica, calcium silicate, calcium stearate, magnesium carbonate, magnesium stearate, magnesium, magnesium phosphate, magnesium silicate, and mixtures thereof.

[0070] The promoter is a polyvalent cation derived from a water-soluble salt, including commonly available sodium chloride, aluminum nitrate, zirconium acetate, and ammonium zirconyl carbonate. The addition of the polyvalent water-soluble salt shortens the time required for radiation during the expansion of the composition. When added, it can be used in amounts from 0.05% to 2% by weight, preferably from 0.1% to 1.2% by weight, based on the total weight of the composition.

[0071] Other materials may be used as needed without adversely affecting the composition and insulating properties of the composition. If desired, other additives and / or salts may be included in the composition to increase its cohesion.

[0072] In a particularly preferred embodiment, the foamable powder-based composition comprises, based on the total weight of the composition:

[0073] (a) 10% to 50% by weight, more preferably 10% to 40% by weight, of at least one powder-based polymer,

[0074] (b) at least one plurality of expandable microspheres, comprising not less than 20% to 70% by weight, more preferably not less than 20% to 50% by weight.

[0075] (c) at least one filler comprising 0% to 70% by weight, more preferably 10% to 60% by weight, and

[0076] (d) 0 to 15% by weight of at least one additive;

[0077] The plurality of expandable microspheres in the composition expand upon heating, and

[0078] The composition has a water content of no more than 3% by weight, based on the total weight of the composition. If the composition contains a high amount of water, the storage stability of the composition will decrease, especially during hot summer months, which may cause the composition to clump or even separate.

[0079] According to the present invention, the composition is preferably stable for at least 2 days when stored at a temperature of 25°C to 45°C, and more preferably stable for at least 7 days when stored at 45°C. The term "storage stable" means that the composition remains homogeneous and does not exhibit agglomerates or grit during storage.

[0080] The composition can be formed as an adhesive or as a coating, and these terms are used interchangeably herein.

[0081] The composition is a powder mixture that can withstand long-term storage and transportation at high temperatures. Furthermore, it is convenient for the end user to add water to the powder mixture before use to form a foamable composition dispersion.

[0082] Foaming method

[0083] Another implementation method disclosed in this article is a foaming method, which includes the following steps:

[0084] (i) A powder mixture comprising: (a) a powder-based polymer in an amount of not less than 8% by weight based on the total weight of the powder mixture; (b) a plurality of expandable microspheres in an amount of not less than 15% by weight based on the total weight of the powder mixture; (c) a filler optionally present; and (d) an additive optionally present, wherein the powder mixture has a water content of not more than 3% by weight based on the total weight of the powder mixture.

[0085] (ii) Add water to the powder mixture obtained in step (i) and mix to form a composition dispersion, wherein the composition dispersion has a solids content greater than 58%; and

[0086] (iii) Expose the dispersion of the composition to conventional or dielectric heating or a combination thereof.

[0087] When heated, the multiple expandable microspheres in the composition dispersion can expand and the composition dispersion can aggregate.

[0088] According to the invention, the composition dispersion obtained in step (ii) has a solids content of greater than 58%, preferably 60% to 80%, more preferably 60% to 75%. If the solids content is equal to or less than 58%, the expansion properties of the foamable composition may be unsatisfactory.

[0089] In a preferred embodiment, in step (ii), water may be added in an amount of less than 41% by weight based on the total weight of the composition dispersion to achieve the desired solids content of the composition dispersion.

[0090] The conventional heating described herein refers to heating in a conventional heater (e.g., an oven). In some embodiments, the compositions of the present invention can be foamed by exposure to conventional heating in a temperature range of 100°C to 177°C. The heating time is preferably no more than 15 seconds, more preferably no more than 12 seconds. If the heating time is too long, the foamed composition may collapse.

[0091] Dielectric heating, electric heating, radio frequency (RF) heating, and high-frequency heating are used interchangeably herein; they are methods of heating dielectric materials using high-frequency alternating electric fields or radio waves. Microwave heating may be included in the dielectric heating described herein.

[0092] In some embodiments, the compositions of the present invention can be foamed by exposure to microwaves with frequencies exceeding 300 MHz to 300 GHz. The heating time is preferably no more than 15 seconds, more preferably no more than 12 seconds. If the heating time is too long, the foamed composition may collapse.

[0093] In other embodiments, the compositions of the present invention can be foamed by exposure to RF heating at a frequency of 2 MHz to 300 MHz.

[0094] The power utilization efficiency of the RF generator is much lower than that of the microwave unit, therefore the microwave unit is the preferred heating source in this invention.

[0095] In some implementations, the foaming method may include a combination of dielectric heating and conventional heating applications. For example, the expansion of microspheres can be achieved by dielectric heating, while the removal of excess moisture after expansion can be achieved by direct heating.

[0096] Methods for forming articles

[0097] Another embodiment relates to a method for forming an article of articles, comprising the following steps:

[0098] (i) A powder mixture comprising: (a) a powder-based polymer in an amount of not less than 8% by weight based on the total weight of the powder mixture; (b) a plurality of expandable microspheres in an amount of not less than 15% by weight based on the total weight of the powder mixture; (c) a filler optionally present; and (d) an additive optionally present, wherein the powder mixture has a water content of not more than 3% by weight based on the total weight of the powder mixture.

[0099] (ii) Add water to the powder mixture obtained in step (i) and mix to form a composition dispersion, wherein the composition dispersion has a solids content of more than 58%;

[0100] (iii) Apply the dispersion of the composition to a first substrate;

[0101] (iv) Applying a second substrate to the composition dispersion to form the article, wherein the composition dispersion is sandwiched between the two substrates; and

[0102] (v) Apply conventional or dielectric heating, or a combination thereof, to the article.

[0103] During heating, once the composition dispersion expands and locks in place, the air gaps within the foamed microspheres provide insulation and structural integrity for the packaging. This packaging is more environmentally friendly than traditional extruded polystyrene foam packaging.

[0104] Preferably, water molecules are effectively removed without leaving unsightly wrinkles or unevenness on the substrate. The uniformity and evenness of the aggregated coating provide uniform insulation for the product and minimize unsightly wrinkles on the substrate, while increasing yield.

[0105] In a preferred embodiment, the first substrate and the second substrate may be independently selected from cellulose substrates, wood or plastics with a melting point greater than 100°C.

[0106] Available cellulose substrates include fiberboard, cardboard, corrugated medium, solid bleached board (SBB), solid bleached sulfite board (SBS), solid unbleached board (SLB), white lined chipboard (WLC), kraft paper, kraft paperboard, coated paper, and binder board.

[0107] The composition dispersions described herein can be used in multilayer substrates, particularly for cellulose substrates. By using the compositions of the present invention, a larger insulating space can be provided between two substrates joined at an adhesive point. Insulating products that can be used herein include paper products for consumer use, such as those for: hot drink cups and lids, cold drink cups and lids, hot food containers and lids, cold food containers and lids, freezer boxes and cartons, envelopes, bags, etc.

[0108] The composition dispersion can be applied to the first substrate in any desired configuration, including: a series of dots, stripes, waves, checkerboard patterns, any general polyhedral shape having a substantially flat substrate, and combinations thereof. Furthermore, the composition dispersion can be applied to the first surface as a series of cylindrical bodies. Moreover, if desired, the composition dispersion can be applied to the first surface as a substantially flat sheet, thereby covering the entire first surface (complete lamination) or covering a portion of the first surface. A second substrate is applied to the top surface of the composition dispersion, thereby forming a sandwich configuration of: first substrate – composition dispersion having expandable microspheres – second substrate.

[0109] In yet another embodiment, the insulating article comprises a substantially flat substrate and a non-flat circular substrate. A composition dispersion is applied to the substantially flat substrate, the non-flat substrate, or both substrates to form the insulating article. The composition dispersion can be applied to completely coat the surface of one or more substrates or selectively coat portions of the surface of one or more substrates. The pattern can be random or various ordered designs. The resulting article thus has an insulating space between the inner surfaces. Articles with patterned compositions simulate spacers inserted between the two substrates. The space between the two substrates is created and maintained by expanded microspheres.

[0110] Optionally, different adhesives can be applied between the two substrates. This is particularly useful for bonding the two substrates together if the composition dispersion has low or no adhesive properties. The different adhesives can be applied before, simultaneously with, or after the composition dispersion is applied to the first substrate. In another embodiment, different adhesives can be applied to the second substrate, and the two substrates can be bonded together using the composition dispersion and the different adhesive sandwiched between them. Exemplary different adhesives include hot melt adhesives, pressure-sensitive adhesives, water-based adhesives, and solvent-based adhesives.

[0111] According to the method of the invention, a composition dispersion is applied between two substrates to form an article, and then exposed to conventional or dielectric heating to aggregate the composition dispersion and cause the microspheres to expand. Thus, heating locks the component containing a plurality of expanded microspheres at appropriate locations on the substrate surface. In the presence of water, the temperature is raised to 100°C, and the water evaporates as the microspheres expand. Expanded microspheres having a Texp of 80°C to 100°C and a Tmax of 90°C to 140°C can be expanded by conventional or dielectric heating.

[0112] Multilayer substrate packaging formed using composition dispersions containing microspheres improves the packaging's ability to withstand strain under constant stress at elevated and / or decreased temperatures. Those skilled in the art will expect that the strain of the composition increases at elevated temperatures through the addition of microspheres.

[0113] According to the present invention, articles formed by the method are suitable as protective packaging, transport packaging, impact-resistant packaging, and insulating packaging. Packaging includes cups, food containers, boxes, cartons, bags, lids, containers, envelopes, parcels, clamshells, etc.

[0114] The invention can be better understood by analyzing the following embodiments, which are non-limiting and are only intended to help explain the invention.

[0115] Example

[0116] The following examples are intended to help those skilled in the art better understand and practice the present invention. The scope of the invention is not limited by the examples, but is defined in the appended claims. Unless otherwise stated, all parts and percentages are based on weight.

[0117] Raw materials:

[0118] AQUENCE EPIX TM 42002 is a water-based polymer foamable composition available from Henkel.

[0119] VINNAPASTM 5044N is a vinyl acetate-ethylene polymer powder, available from Wacker.

[0120] Corn starch is available from Cargill.

[0121] Dextrin can be obtained from Tianzhu Chemical.

[0122] Expancel TM 031WUF 40 is an expandable microsphere with a Texp of 80℃ and a Tmax of 135℃, available from Nouryon.

[0123] NaCl can be obtained from Guangdong Guanghua Chemical Factory.

[0124] Test method:

[0125] Solid content:

[0126] Solid content was determined by drying 1 gram of dispersion in a conventional oven at 80°C for 30 minutes, and then weighing it using a precision balance to calculate the solid content as a percentage. The solid content of all composition dispersions is recorded in Tables 2 and 4.

[0127] Expansion ratio:

[0128] All composition samples were applied to a paper substrate (80 g / m²) in a series of dot patterns while still wet. 3 Kraft paper, which is available from Youtai. Each substrate was activated by microwave heating (700W, 10s). The initial height of the coating and the final height after activation were recorded, and the expansion ratio was calculated using the following equation, and recorded in Tables 2 and 4:

[0129]

[0130] The expansion ratios are given in the form of “XY” in Tables 2 and 4, where X is calculated based on the minimum height of the point and Y is calculated based on the maximum height of the point.

[0131] AQUENCE EPIX TM The expansion ratio of 42002 was also tested and calculated using the method described above. The result was defined as a baseline. Foamable composition dispersions with an expansion ratio not less than the baseline were considered acceptable.

[0132] Storage stability:

[0133] Each sample was stored in a wide-mouth flask at a rate of 65.5 g and kept in a conventional oven at 45°C for 7 days. Then, 35 g of water was added to each sample to obtain a dispersion. The storage stability of each sample was visually observed and defined using the following scale:

[0134] A Stable dispersion with no visible sand particles B Dispersions containing visible sand grains C Phase separation

[0135] Grade A is considered acceptable.

[0136] Preparation of foamable compositions:

[0137] The foamable composition is prepared by the following method using the components in the amounts (parts by weight) listed in Table 1 below.

[0138] Table 1.

[0139] <![CDATA[VINNAPAS TM 5044N]]> 25 25 10 5 25 <![CDATA[Expancel TM 031WUF 40]]> 20 30 55 20 10 corn starch 10 5 0 20 15 dextrin 10 5 0 20 15 NaCl 0.5 0.5 0.5 0.5 0.5 total 65.5 65.5 65.5 65.5 65.5

[0140] Each foamable composition is prepared by mixing the components in a container.

[0141] Preparation of the composition dispersions and their swelling properties:

[0142] Five composition dispersions were prepared by adding 35 grams of water to each of the foamable compositions obtained above. Additionally, 100.5 grams of AQUENCE EPIX were prepared separately. TM 42002 (marked as Comparative Example 3). The properties of the six composition dispersions were tested using the methods described above and recorded in Tables 2 and 3 below.

[0143] Table 2.

[0144]

[0145] Table 3.

[0146] Inflation Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

[0147] The expansion ratios of Examples 1, 2, and 3 of the present invention are significantly greater than those of Comparative Example 3. Meanwhile, compositions containing powder-based polymers or expanded microspheres that are not within the scope of protection of the present invention (Comparative Examples 1 to 3) did not exhibit satisfactory expansion ratios.

[0148] A photograph of the composition dispersion after activation on paper is shown. Figures 1 to 5 middle. Figure 1 and 2 The embodiments of the invention shown provide consistent and uniform expansion, while Comparative Examples 1 to 3 ( Figures 3 to 5 The composition did not exhibit consistent expansion.

[0149] Effect of solid content on expansion ratio:

[0150] To understand the effect of the solids content of the composition dispersion on the foaming properties, two Examples 1 were prepared, one with 35 g of water and the other with 55 g of water, to obtain composition dispersions with different solids contents, as recorded in Examples 1 and Comparative Example 4. The properties were tested using the methods described above and recorded in Table 4 below.

[0151] Table 4.

[0152] Solid content (%) 0.66 0.58 Initial height of coating (mm) 0.284 0.275 Final height of the activated coating (mm) 0.458-0.560 0.324-0.456 Expansion ratio (%) 61-97 18-65 Inflation Figure 1 Figure 6

[0153] from Figure 1 and 6 It can be seen that the composition dispersion with a solid content greater than 58% provides consistent and uniform expansion.

[0154] Storage stability test results:

[0155] Four examples with formulations similar to Example 1 were prepared, but with different amounts of water added to form Examples 1a to 1d having water content ranges (based on weight % of the foamable composition) listed in Table 5 below. The storage stability characteristics of Examples 1a to 1d and Comparative Example 3 were tested using the methods described above and recorded in Table 6 below.

[0156] Table 5.

[0157] <![CDATA[VINNAPAS TM 5044N]]> 25.000 24.260 23.750 23.250 <![CDATA[Expancel TM 031WUF 40]]> 20.000 19.400 19.000 18.600 corn starch 10.000 9.700 9.500 9.300 dextrin 10.000 9.700 9.500 9.300 NaCl 0.500 0.480 0.475 0.465 water 0 1.965 3.275 4.585 gross weight 65.500 65.500 65.500 65.500 Water content (%) 0 3 5 7

[0158] Table 6.

[0159] Storage stability level A A B B C

[0160] The compositions of the present invention having a water content of no more than 3% by weight (based on the weight of the foamable composition) exhibit satisfactory storage stability.

[0161] Although some preferred embodiments have been described, many modifications and variations can be made to them in light of the above teachings. Therefore, it should be understood that the invention can be practiced in ways other than those specifically described without departing from the scope of the appended claims.

Claims

1. A foamable powder-based composition comprising: (a) at least one powder-based polymer, wherein the amount based on the total weight of the composition is not less than 8% by weight. (b) at least one plurality of expandable microspheres, the amount of which, based on the total weight of the composition, is not less than 15% by weight, and (c) At least one filler, wherein the filler is selected from corn starch, pearl starch, physically modified starch, chemically modified starch, dextrin, and mixtures thereof. The plurality of expandable microspheres in the composition expand upon heating; and The composition wherein the composition has a water content of no more than 3% by weight of the total weight of the composition.

2. The foamable powder-based composition according to claim 1, wherein the powder-based polymer is selected from vinyl acetate homopolymers, copolymers prepared from vinyl acetate and at least one other monomer, copolymers prepared from vinyl chloride and at least one other monomer, and mixtures thereof.

3. The foamable powder-based composition according to claim 1 or 2, wherein the expandable microspheres have a hydrocarbon core and a polyacrylonitrile shell.

4. The foamable powder-based composition according to claim 1 or 2, wherein the expandable microspheres have an initial expandable temperature range of 80°C to 110°C and a maximum expandable temperature range of 90°C to 135°C.

5. The foamable powder-based composition according to claim 1 or 2, wherein the composition further comprises (d) at least one additive selected from plasticizers; pigments; dyes; stabilizers; anti-caking agents; dispersants; accelerators selected from sodium chloride, aluminum nitrate, zirconium acetate, zirconium oxycarbonate, and mixtures thereof; and mixtures thereof.

6. The foamable powder-based composition according to claim 1 or 2, wherein the powder-based polymer is present in an amount of 10% to 50% by weight based on the total weight of the composition.

7. The foamable powder-based composition according to claim 6, wherein the powder-based polymer is present in an amount of 10% to 40% by weight based on the total weight of the composition.

8. The foamable powder-based composition according to claim 1 or 2, wherein the expandable microspheres are present in an amount of not less than 20% to 70% by weight based on the total weight of the composition.

9. The foamable powder-based composition according to claim 8, wherein the expandable microspheres are present in an amount of not less than 20% to 50% by weight, based on the total weight of the composition.

10. The foamable powder-based composition according to claim 1 or 2, wherein the filler is present in an amount greater than 0 to 70% by weight based on the total weight of the composition.

11. The foamable powder-based composition of claim 10, wherein the filler is present in an amount of 10% to 60% by weight based on the total weight of the composition.

12. The foamable powder-based composition according to claim 1 or 2, wherein the composition is stored stably at 45°C for at least 7 days.

13. A foaming method, comprising the following steps: (i) A powder mixture comprising: (a) a powder-based polymer in an amount of not less than 8% by weight based on the total weight of the powder mixture; (b) a plurality of expandable microspheres in an amount of not less than 15% by weight based on the total weight of the powder mixture; (c) a filler optionally present; and (d) an additive optionally present, wherein the powder mixture has a water content of not more than 3% by weight based on the total weight of the powder mixture. (ii) Add water to the powder mixture obtained in step (i) and mix to form a composition dispersion, wherein the composition dispersion has a solids content greater than 58%; and (iii) Expose the dispersion of the composition to conventional or dielectric heating or a combination thereof.

14. A method for forming an article, comprising the following steps: (i) A powder mixture comprising: (a) a powder-based polymer in an amount of not less than 8% by weight based on the total weight of the powder mixture; (b) a plurality of expandable microspheres in an amount of not less than 15% by weight based on the total weight of the powder mixture; (c) a filler optionally present; and (d) an additive optionally present, wherein the powder mixture has a water content of not more than 3% by weight based on the total weight of the powder mixture. (ii) Water is added to the powder mixture obtained in step (i) and mixed to form a composition dispersion, wherein the composition dispersion has a solid content of more than 58%; (iii) Apply the composition dispersion to a first substrate; (iv) Applying a second substrate to the composition dispersion to form the article, wherein the composition dispersion is sandwiched between the two substrates; as well as (v) Apply conventional or dielectric heating, or a combination thereof, to the article.

15. The method of claim 14, wherein the first substrate and the second substrate are independently selected from cellulose substrates, wood, or plastics with a melting point greater than 100°C.

16. The method according to claim 15, wherein the cellulose substrate is fiberboard, cardboard, corrugated cardboard, corrugated base paper, homogeneous bleached board, homogeneous bleached sulfite board, homogeneous unbleached board, white inner linerboard, kraft paper, kraft paperboard, coated paper, or cover paperboard.

17. The method of claim 14, wherein the composition dispersion is applied in the form of a pattern of dots, stripes, waves, checkerboard, or a polyhedral shape having a substantially flat base.

18. The method of claim 14, further comprising the step of applying an adhesive between the first substrate and the second substrate, wherein the adhesive is a hot melt adhesive.

19. The method of claim 14, wherein the dielectric heating is microwave heating or radio frequency heating or a combination thereof.

20. The method of claim 14, wherein the article is a cup, food container, lid, wrapping, or flip-top container.

21. The method of claim 20, wherein the article is a box, bag, container, or envelope.

22. The method of claim 21, wherein the article is a cardboard box.

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