Foamable powder-based composition and method for foaming same

Abstract

Described herein is an expandable powder-based composition comprising: (a) at least one powder-based polymer in an amount of 8 wt. % or more based on the total weight of the composition; (b) at least one expandable microsphere in an amount of 15 wt. % or more based on the total weight of the composition; and (c) optionally, at least one filler, wherein the expandable microspheres in the composition expand upon heating, and the composition has a moisture content of 3 wt. % or less of the total weight of the composition.

Description

[Technical field]

[0001] FIELD OF THEINVENTION The present invention relates to an effervescent powder-based composition and a method for effervescent thereof. More particularly, the present invention relates to an effervescent powder-based composition that can withstand long-term storage and transportation at high temperatures, and a method for effervescent thereof. [Background technology]

[0002] There is a demand for disposable food packages and containers that are more environmentally friendly than traditional closed-cell extruded polystyrene foam packaging. Packages made entirely from plastic typically do not biodegrade in less than 400 years, or may never biodegrade again. As a result, some regulations prohibit the use of such packages and containers.

[0003] There is a need for alternative packaging that is recyclable, biodegradable and / or compostable. One such package is a cellulosic substrate sourced from recycled and / or compostable materials. The package is made by bonding two cellulosic substrates together through an air gap. The drawbacks of these alternative packages include poorer insulation and lower structural integrity than plastic packages; when the package is handled or bent, the air gap between the two substrates is compressed, reducing the insulation in the compressed area. Insulation can be improved by increasing the air gap between the cellulosic substrate layers, increasing the thickness of the cellulosic substrate, or inserting a cellulosic medium between the two layers.

[0004] Some of the above improved packages are described in US 9,580,629 B2, US 8,747,603 B2, US 9,273,230 B2, US 9,657,200 B2, US 20140087109 A1, US 20170130399 A1, US 20170130058 A1, and US 20160263876 A1. The packages are formed with an air gap in the coating / adhesive / foamable composition sandwiched between two substrates to provide thermal insulation. However, these packages may result in non-uniform insulation when the thickness of the substrate exceeds 1.5 inches. WO 2019 / 018523 A1 disclosed an improved foaming method by exposing the foamable composition to dielectric heating to achieve uniform insulation for packages of different sizes. Although the aforementioned coating / adhesive / foaming compositions are all water-based or emulsion-based, which can improve the thermal insulation properties of packages, water-based or emulsion-based compositions have limited shelf life and are inconvenient to transport, especially in summer when the temperature exceeds 35°C, as liquid-based compositions may foam and eventually cause phase separation at high temperatures. Moreover, they are smaller in weight and volume than traditional products, which can reduce transportation costs. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] U.S. Pat. No. 9,580,629 [Patent Document 2] U.S. Pat. No. 8,747,603 [Patent Document 3] U.S. Patent No. 9,273,230 [Patent Document 4] U.S. Patent No. 9,657,200 [Patent Document 5] US Patent Publication No. 20140087109 [Patent Document 6] US Patent Publication No. 20170130399 [Patent Document 7] US Patent Publication No. 20170130058 [Patent Document 8] US Patent Publication No. 20160263876 [Patent Document 9] International Publication No. 2019 / 018523 Summary of the Invention [Problem to be solved by the invention]

[0006] There is a need in the art for foamable compositions and foaming methods that can withstand extended storage and transportation at elevated temperatures while achieving improved foamability so as to provide thermal insulation during the manufacture of articles. [Means for solving the problem]

[0007] One embodiment disclosed herein comprises the following: (a) at least one powdered base polymer in an amount of 8% by weight or more, based on the total weight of the composition; (b) at least one plurality of expandable microspheres in an amount of 15% by weight or more based on the total weight of the composition; and (c) optionally, at least one filler 1. An effervescent powder-based composition comprising: wherein the plurality of expandable microspheres in the composition expand upon heating; The composition has a moisture content of 3% by weight or less, based on the total weight of the composition.

[0008] Another embodiment is directed to a foaming method comprising the steps of: (i) forming a powder mixture of (a) one powdered base polymer in an amount of 8 wt.% or more based on the total weight of the powder mixture, (b) one expandable microsphere powder in an amount of 15 wt.% or more based on the total weight of the powder mixture, (c) optionally one filler, and (d) optionally additives, wherein the powder mixture has a moisture content of 3 wt.% or less based on the total weight of the powder mixture; (ii) adding water to the powder mixture obtained in step (i) and mixing to form a composition dispersion, wherein the composition dispersion has a solid content of greater than 58%; and (iii) exposing the composition dispersion to conventional heating or dielectric heating or a combination thereof.

[0009] Yet another embodiment relates to a process for forming an article, comprising the steps of: (i) forming a powder mixture of (a) one powder base polymer in an amount of 8 wt.% or more based on the total weight of the powder mixture, (b) one plurality of expandable microspheres in an amount of 15 wt.% or more based on the total weight of the powder mixture, (c) optionally one filler, and (d) optionally additives, wherein the powder mixture has a moisture content of 3 wt.% or less based on the total weight of the powder mixture; (ii) adding water to the powder mixture obtained in step (i) and mixing to form a composition dispersion, wherein the composition dispersion has a solid content of greater than 58%; and (iii) applying a composition dispersion onto a first substrate; (iv) applying a second substrate onto the composition dispersion, thereby forming an article, where the composition dispersion is sandwiched between two substrates; and (v) applying conventional or dielectric heating or a combination thereof to the article.

[0010] Other features and aspects of the present subject matter are described in further detail below. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 shows a photograph of the composition of Example 1 that was activated by microwave heating immediately after expansion of the microspheres. [Diagram 2] FIG. 2 shows a photograph of the composition of Example 3 that was activated by microwave heating immediately after expansion of the microspheres. [Diagram 3]FIG. 3 shows a photograph of the composition of Comparative Example 1 that was activated by microwave heating immediately after expansion of the microspheres. [Figure 4] FIG. 4 shows a photograph of the composition of Comparative Example 2 that was activated by microwave heating immediately after expansion of the microspheres. [Diagram 5] FIG. 5 shows a photograph of the composition of Comparative Example 3 that was activated by microwave heating immediately after expansion of the microspheres. [Figure 6] FIG. 6 shows a photograph of the composition of Comparative Example 4 that was activated by microwave heating immediately after expansion of the microspheres. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Those skilled in the art will appreciate that this disclosure is a description of exemplary embodiments only and is not intended to limit the broad aspects of the invention.

[0013] For purposes of the present invention, unless otherwise stated, the terms used shall be construed in accordance with the following definitions.

[0014] As used herein, unless otherwise stated, the terms "a," "an," and "the" include singular and plural referents.

[0015] As used herein, the terms "comprising" and "comprises" are synonymous with "including," "includes," or "containing," "contains," and are inclusive or open-ended and do not exclude additional, unrecited members, elements, or process steps.

[0016] The terms "at least one" or "one or more" as used herein to define a component refer to the type of component and not to an absolute number of molecules.

[0017] Unless otherwise specified, "about" as used herein in relation to a numerical value refers to ±10% of the numerical value, preferably ±5% of the value. Thus, for example, "about 20% by weight" relates to a weight of 20±2% by weight, preferably 20±1% by weight.

[0018] Unless otherwise specified, the recitation of numerical endpoints includes all numbers and fractions subsumed within the respective ranges, as well as the recited endpoints.

[0019] Unless otherwise defined, all terms used herein, including technical and scientific terms, have the meaning commonly understood by one of ordinary skill in the art to which this invention belongs.

[0020] According to a first aspect of the invention, the present invention provides an effervescent powder-based composition comprising: (a) at least one powdered base polymer in an amount of 8% by weight or more, based on the total weight of the composition; (b) at least one expandable microsphere in an amount of 15% by weight or more 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; The composition has a moisture content of 3% by weight or less, based on the total weight of the composition.

[0021] (a) Powder-based polymer According to the invention, the expandable powder base composition comprises at least one powder base polymer in an amount of 8% by weight or more, based on the total weight of the composition.

[0022] The powdered base polymer may comprise any desired polymeric component, including vinyl acetate homopolymer, copolymers made from vinyl acetate and at least one other monomer, copolymers made from vinyl chloride and at least one other monomer, and mixtures thereof. Particularly preferably, the powdered base polymer may be a copolymer made from vinyl acetate and at least one other monomer, such as ethylene.

[0023] The powdered base polymer used as component (a) can be prepared by spray drying the polymer dispersion. When the powdered base polymer comes into contact with water, the dispersible polymer powder particles disintegrate and release the individual dispersed particles again. The dispersed polymer powder has the same properties as the original dispersion.

[0024] Useful powdered base polymers are commercially available under a variety of trade names, including, for example, VINNAPAS™ 5044 N, 5043 N, 4121 N, 4042 H and 5048 H, manufactured by Wacker.

[0025] Particularly preferably, the powdered base polymer may be present in an amount of from 10% to 50% by weight, more preferably from 10% to 40% by weight, based on the total weight of the composition.

[0026] (b) Expandable microspheres According to the present invention, the effervescent powder-based composition comprises at least 15 wt. % of a plurality of expandable microspheres based on the total weight of the composition, wherein the plurality of expandable microspheres in the composition expand upon heating.

[0027] Expandable microspheres useful in the present invention expand in size in the presence of heat. Expandable microspheres useful in the present invention include, for example, thermally expandable polymeric microspheres, including those with a hydrocarbon core and a polyacrylonitrile shell (such as those sold under the trade name DUALITE™) and other similar microspheres (such as those sold under the trade name EXPANCEL™). The expandable microspheres can have any unexpanded size, including diameters of about 5 microns to about 30 microns. In the presence of heat, the expandable microspheres of the present invention can increase in diameter from about 3 to about 10 times their original size. When the microspheres expand in the composition, the composition becomes a foam-like material with improved insulating properties. The microspheres are usually made with a plastic or polymer shell, in which is a blowing agent designed to activate when a certain temperature is reached.

[0028] 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 usually sold with a specific expansion temperature (Texp) and a maximum expansion temperature (Tmax). The initial expansion temperature (Texp) is the general temperature (Texp) at which the microspheres begin to expand, and the maximum expansion temperature (Tmax) is the temperature at which approximately 80% of the microsphere has expanded. If the microspheres are exposed to a temperature much higher than Tmax, they will explode and begin to shrink.

[0029] One particularly useful microsphere has a Texp between 80° C. and 105° C. The temperature at which the microsphere reaches maximum expansion (Tmax) is desirably between 90° C. and 135° C.

[0030] In a preferred embodiment, the density of the expandable microspheres is 10 kg / m 3 It is desirable that it be less than this.

[0031] Depending on the amount of microspheres and the type of polymer, the foamable powder-based composition can have adhesive properties: high levels of microspheres provide low adhesive or non-adhesive properties, while low levels, less than about 30% by weight based on the total weight of the composition, provide adhesive properties to the composition.

[0032] Depending on the fully expanded size of the microspheres, the amount of expandable microspheres in the composition can be adjusted. Depending on the particular expandable microspheres used in the composition, the desired amount of microspheres in the composition may vary.

[0033] Component (b) further enhances the structural integrity of the composition after expansion. Introducing voids into the matrix would normally reduce mechanical integrity, but component (b) in the composition provides rigidity when applied to a substrate. This is particularly useful when packaging fragile contents.

[0034] In another embodiment, component (b) may be pre-expanded. In yet another embodiment, the microspheres may be a mixture of pre-expanded and expandable microspheres.

[0035] Commercially available products may be used in the present invention, examples of which include Expancel™ 031 WUF 40 available from Nouryon and F-SF 36 available from Matsumoto.

[0036] In a preferred embodiment, the expandable microspheres may be present in the composition in an amount of 20% to 70% by weight, more preferably 20% to 50% by weight, based on the total weight of the composition. The expansion rate of the expandable microspheres and the loading level of the microspheres are related to each other.

[0037] (c) Filler According to the present invention, the foamable composition powder system optionally comprises at least one filler.

[0038] Examples of 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 after adding water.

[0039] Commercially available products can also be used in the present invention, such as corn starch from Cargill and dextrin from Tianzhu Chemical.

[0040] Particularly preferably, the filler may be present in an amount of from 0% to 70% by weight, more preferably from 10% to 60% by weight, based on the total weight of the composition.

[0041] (d) Additives The composition of the present invention optionally further comprises (d) at least one additive selected from the following: plasticizers, pigments, dyes, stabilizers, anticaking agents, dispersants, accelerators which are polyvalent water-soluble salts, and mixtures thereof. These components may be included in an amount of 0 to 15% by weight, based on the total weight of the composition.

[0042] Exemplary plasticizers are the dibenzoates available under the trademark BENZOFLEX, such as diethylene glycol dibenzoate, dipropylene glycol dibenzoate, etc.

[0043] Exemplary anti-caking agents include aluminum, silica, calcium silicate, calcium stearate, magnesium carbonate, magnesium stearate, magnesium, magnesium phosphate, magnesium silicate, and mixtures thereof.

[0044] Accelerators are polyvalent cations from water-soluble salts including commonly available sodium chloride, aluminum nitrate, zirconium acetate, and ammonium zirconyl carbonate. The addition of polyvalent water-soluble salts reduces the time required for radiation during expansion of the composition. When added, they may be used at 0.05% to 2% by weight, preferably 0.1 to 1.2% by weight, based on the total weight of the composition.

[0045] Other materials that do not adversely affect the composition and insulating properties of the composition may be used if desired. Other additives and / or salts may also be included in the composition, if desired, to enhance the cohesion of the composition.

[0046] In a particularly preferred embodiment, the effervescent powder base composition comprises, based on the total weight of the composition: (a) from 10% to 50% by weight, more preferably from 10% to 40% by weight, of at least one powdered base polymer; (b) 20% to 70% by weight, more preferably 20% to 50% by weight, of at least one type of expandable microspheres; (c) 0 to 70% by weight, more preferably 10% to 60% by weight, of at least one filler, and (d) 0% to 15% by weight of at least one additive; wherein the plurality of expandable microspheres in the composition expand upon heating; The composition has a water content of 3% by weight or less based on the total weight of the composition.If the composition contains a large amount of water, the storage stability of the composition will decrease, especially in hot summer, and the composition will solidify or even undergo phase separation.

[0047] According to the present invention, the composition is preferably storage stable for at least 2 days at 25° C. to 45° C., more preferably storage stable for at least 7 days at 45° C. The term “storage stable” means that the composition remains homogenous and does not exhibit agglomerates or particulates during storage.

[0048] The composition may be formed as an adhesive or a coating, which may be used interchangeably herein.

[0049] The composition is a powder mix that can withstand long-term storage and transportation at high temperatures, and it is convenient for the end user to add water to the powder mix to form a foamable composition dispersion prior to use.

[0050] Foaming Method Another embodiment disclosed herein is a foaming method comprising the steps of: (i) forming a powder mixture of (a) one powder base polymer in an amount of 8 wt.% or more based on the total weight of the powder mixture, (b) one or more expandable microspheres in an amount of 15 wt.% or more based on the total weight of the powder mixture, (c) optionally one filler, and (d) optionally additives, wherein the powder mixture has a moisture content of 3 wt.% or less based on the total weight of the powder mixture; (ii) adding water to the powder mixture obtained in step (i) and mixing to form a composition dispersion, wherein the composition dispersion has a solid content of greater than 58%; and (iii) exposing the composition dispersion to conventional heating or dielectric heating or a combination thereof.

[0051] Upon heating, the plurality of expandable microspheres in the composition dispersion may expand and cause the composition dispersion to coalesce.

[0052] According to the present invention, the composition dispersion obtained in step (ii) has a solid content of more than 58%, preferably 60%-80%, more preferably 60%-75%. If the solid content is equal to or less than 58%, the expansion performance of the foamable composition may be insufficient.

[0053] In a preferred embodiment, in step (ii), water may be added in an amount of less than 41 wt. %, based on the total weight of the composition dispersion, to reach a desired solids content of the composition dispersion.

[0054] Conventional heating as used herein refers to heating in a conventional heater such as an oven. In some embodiments, the composition of the present invention can be foamed by exposure to conventional heating in the temperature range of 100°C to 177°C. The heating time is preferably 15 seconds or less, more preferably 12 seconds or less. If the heating time is too long, the foamed composition may collapse.

[0055] Dielectric heating, electron heating, radio frequency (RF) heating, and radio frequency heating, all used interchangeably herein, are processes in which high frequency alternating electric or radio waves heat a dielectric material. Microwave heating may be included in dielectric heating herein.

[0056] In some embodiments, the composition of the present invention can be foamed by exposure to microwaves having a wavelength of more than 300 MHz to 300 GHz. The heating time is preferably 15 seconds or less, more preferably 12 seconds or less. If the heating time is too long, the foamed composition may collapse.

[0057] In another embodiment, the compositions of the present invention can be foamed by exposure to RF heating at frequencies between 2 MHz and 300 MHz.

[0058] The power utilization efficiency of RF generators is much lower than that of microwave units, which is why microwave units are the preferred heating source in the present invention.

[0059] In some embodiments, the foaming method may include a combination of dielectric heating and conventional heating applications, for example, expansion of the microspheres may be achieved by dielectric heating, and removal of excess water after expansion may be achieved by direct heating.

[0060] Method for forming an article Another embodiment is directed to a method of forming an article comprising the steps of: (i) forming a powder mixture of (a) one powder base polymer in an amount of 8 wt.% or more based on the total weight of the powder mixture, (b) one or more expandable microspheres in an amount of 15 wt.% or more based on the total weight of the powder mixture, (c) optionally one filler, and (d) optionally additives, wherein the powder mixture has a moisture content of 3 wt.% or less based on the total weight of the powder mixture; (ii) adding water to the powder mixture obtained in step (i) and mixing to form a composition dispersion, wherein the composition dispersion has a solids content of greater than 58%; (iii) applying a composition dispersion onto a first substrate; (iv) applying a second substrate onto the composition dispersion, thereby forming an article, where the composition dispersion is sandwiched between two substrates; and (v) applying conventional or dielectric heating or a combination thereof to the article.

[0061] Upon heating, the composition dispersion expands and locks into place, and the voids in the expanded microspheres provide insulation and structural integrity to the package, which is more environmentally friendly than traditional extruded polystyrene foam packaging.

[0062] It is desirable for the water molecules to be expelled efficiently without leaving unsightly wrinkles or irregularities on the substrate. The uniformity and homogeneity of the combined coating provides uniform insulation to the article, minimizes unsightly wrinkles on the substrate, and improves productivity.

[0063] In a preferred embodiment, the first substrate and the second substrate may each independently be selected from a cellulosic substrate, wood, or a plastic having a melting point above 100°C.

[0064] Useful cellulosic substrates include fiberboard, chipboard, corrugated cardboard, corrugated board, solid bleached board (SBB), solid bleached sulphite board (SBS), solid unbleached board (LB), white lined chipboard (WLC), kraft paper, kraft board, coated paper, binder board, and the like.

[0065] The composition dispersion described herein can be useful for multi-layer substrates, especially cellulose substrates.The composition of the present invention can be used to provide a larger insulation space between two substrates that are bonded at the bonding point.The insulation products useful herein include consumer paper products such as hot drink cups and lids, cold drink cups and lids, hot food containers and lids, cold food containers and lids, freezer cartons and cases, envelopes, bags, etc.

[0066] The composition dispersion may be applied to the first substrate in any desired configuration, including a series of dots, stripes, waves, checkerboard patterns, any generally polyhedral shape with a substantially flat bottom, and combinations thereof. Additionally, the composition dispersion may be applied to the first surface in a series of circles. Additionally, if desired, the composition dispersion may be applied to the first surface as a substantially flat sheet, covering the entire first surface (full lamination) or covering only a portion of the first surface. A second substrate applied on top of the composition dispersion forms a sandwich configuration of first substrate-composition dispersion with expandable microspheres-second substrate.

[0067] In yet another embodiment, the insulating article includes a substantially flat substrate and a non-flat round substrate. The composition dispersion is applied to either the substantially flat substrate, the non-flat substrate, or both substrates to form the insulating article. The composition dispersion may be applied to completely coat the surface of the substrate or to selectively coat a portion of the surface of the substrate. The pattern may be random or of various order designs. Thus, the resulting article has an insulating space between the liner surfaces. The article with the patterned composition mimics a partition interposed between the two substrates. The space between the two substrates is created and maintained by the expanded microspheres.

[0068] In some cases, a different adhesive may be applied between the two substrates. This is particularly useful for bonding two substrates when the composition dispersion has low or no adhesive properties. The different adhesive may be applied before, at the same time, or after the composition dispersion is applied to the first substrate. In another embodiment, a different adhesive may be applied to the second substrate, and the two substrates may be bonded with the composition dispersion and the different adhesive sandwiched between the two substrates. Examples of different adhesives include hot melt adhesives, pressure sensitive adhesives, water-based adhesives, and solvent-based adhesives.

[0069] According to the method of the present invention, the composition dispersion is applied between two substrates to form an article, which is then exposed to conventional or dielectric heating to fuse the composition dispersion and expand the microspheres. Thus, the heating fixes the component, which includes a plurality of expanded microspheres, to the surface of the substrate. If water is present, the temperature is increased to 100°C, and the water evaporates while the microspheres expand. The expanded microspheres can be expanded by conventional or dielectric heating with Texp between 80°C and 100°C and Tmax between 90°C and 140°C.

[0070] Multi-layer substrate packages formed with composition dispersions containing microspheres improve the distortion resistance of the package under constant stress at high and / or low temperatures. At high temperatures, one skilled in the art would expect the addition of microspheres to increase distortion of the composition.

[0071] According to the present invention, articles formed by the process are suitable as protective, shipping, impact resistant, and insulating packages, including cups, food containers, cases, cartons, bags, lids, boxes, envelopes, wraps, clamshells, and the like.

[0072] The invention can be better understood by analyzing the following examples, which are non-limiting and are intended only to illustrate the invention. EXAMPLES

[0073] The following examples are intended to assist those skilled in the art in better understanding and practicing the present invention. The scope of the present invention is not limited by the examples, but is defined by the appended claims. Unless otherwise specified, all parts and percentages are by weight.

[0074] [Ingredients:] AQUENCE EPIX™ 42002 is a water-based polymeric foamable composition available from Henkel. VINNAPAS™ 5044 N is a vinyl acetate-ethylene polymer powder available from Wacker. Corn starch is available from Cargill. Dextrin is available from Tianzhu Chemicals. Expancel™ 031 WUF 40 is an expandable microsphere with a Texp of 80° C. and a Tmax of 135° C., available from Nouryon. NaCl is available from Guangdong Guanghua Chemical Factory.

[0075] [Test method:] Solids content: The solids content was measured by drying 1 gram of the dispersion in a conventional oven at 80° C. for 30 minutes, then weighing it on a precision balance and calculating the solids content in percentage. The solids content of all the composition dispersions is recorded in Tables 2 and 4.

[0076] [Expansion rate:] All composition samples were applied in a wet state in a series of dot patterns onto a paper substrate (80 g / m2 available from Youtai Co., Ltd.). 3 The coating was applied to a 100 mm thick sheet of 100 mm thick paper (brown paper). Each substrate was activated by microwave heating (700 w, 10 seconds). The initial height of the coating and the final height after activation were recorded, and the expansion ratio was calculated according to the following formula and recorded in Tables 2 and 4. Expansion rate = (final height after activation - initial height of coating) / (initial height of coating) x 100%

[0077] The expansion rates are reported in Tables 2 and 4 in the form of "XY," where X was calculated based on the minimum dot height and Y was calculated based on the maximum dot height.

[0078] The expansion rate of AQUENCE EPIX™ 42002 was also tested and calculated using the above method. The results were established as a benchmark. A foamable composition dispersion having an expansion rate equal to or greater than the benchmark was considered acceptable.

[0079] Storage stability: 65.5 g of each sample was placed in a bottle 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 on the following scale:

[0080] TIFF2025504001000001.tif25123

[0081] A level was considered acceptable.

[0082] Preparation of the foamable composition: The foamable compositions were prepared in the following manner using the components in the amounts (parts by weight) shown in Table 1 below.

[0083] [Table 1]

[0084] Each foamable composition was prepared by mixing the ingredients in a container.

[0085] [Preparation of composition dispersion and its expansion performance:] 35 grams of water was added to each of the foaming compositions obtained above to prepare five composition dispersions.Furthermore, AQUENCE EPIX® 42002 was separately prepared in a weight of 100.5 grams (shown as Comparative Example 3).The properties of the six composition dispersions were tested using the above method and recorded in Tables 2 and 3 below.

[0086] [Table 2]

[0087] [Table 3]

[0088] The expansion ratios of Examples 1, 2 and 3 of the present invention were obviously greater than that of Comparative Example 3. On the other hand, the compositions having powdered base polymers or expanded microspheres outside the scope of the present invention (Comparative Examples 1-3) did not show satisfactory expansion ratios.

[0089] Photographs of the composition dispersions after activation on paper are shown in Figures 1 to 5. The inventive examples shown in Figures 1 and 2 provided consistent and uniform expansion, whereas Comparative Examples 1 to 3 (Figures 3 to 5) did not provide consistent expansion of the compositions.

[0090] (Effect of solid content on expansion rate:) In order to understand the effect of the solid content of the composition dispersion on the foaming properties, two Example 1s were prepared separately, one was added with 35g water, and the other was added with 55g water, to obtain composition dispersions with different solid content, which were recorded as Example 1 and Comparative Example 4. The properties were tested using the above methods and recorded in Table 4 below.

[0091] [Table 4]

[0092] As can be seen from Figures 1 and 6, composition dispersions having solids levels greater than 58% provided consistent and uniform expansion.

[0093] (Storage stability test results:) Four examples were prepared separately having the same composition as Example 1, but with different amounts of water added to form Examples 1a-1d, with the range of water contents (wt % based on the weight of the foamable composition) shown below in Table 5. The storage stability of Examples 1a-1d and Comparative Example 3 was tested using the method described above and recorded below in Table 6.

[0094] [Table 5]

[0095] [Table 6]

[0096] Compositions of the present invention having a moisture content of 3% by weight or less (% by weight based on the weight of the foamable composition) have sufficient storage stability.

[0097] While several preferred embodiments have been described, many modifications and variations are possible in light of the above teachings, and it is therefore understood that the invention can be practiced otherwise than as specifically described without departing from the scope of the appended claims.

Claims

1. (a) at least one powdered base polymer in an amount of 8% by weight or more, based on the total weight of the composition; (b) at least one expandable microsphere in an amount of 15% by weight or more based on the total weight of the composition; and (c) optionally, at least one filler; 1. An effervescent powder-based composition comprising: wherein the plurality of expandable microspheres in the composition expand upon heating; The composition has a moisture content of 3% or less by weight of the total weight of the composition. Effervescent powder-based composition.

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

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

4. 3. The effervescent powder-based composition according to claim 1 or 2, wherein the expandable microspheres have an initial expansion temperature range of 80°C to 110°C and a maximum expansion temperature range of 50°C to 150°C.

5. The effervescent powder-based composition according to any of claims 1 to 4, wherein the filler is selected from corn starch, pearl starch, physically modified starches, chemically modified starches, dextrins, and mixtures thereof.

6. 6. The effervescent powder base composition according to any of claims 1 to 5, wherein the composition further comprises (d) at least one additive selected from plasticizers, pigments, dyes, stabilizers, anti-caking agents, dispersants, accelerators which are polyvalent water-soluble salts, and mixtures thereof.

7. 7. The effervescent powder base composition of claim 6, wherein the accelerator is selected from sodium chloride, aluminum nitrate, zirconium acetate, ammonium zirconyl carbonate, and mixtures thereof.

8. 8. The expandable powder-based composition according to any of the preceding claims, wherein the powder base polymer is present in an amount of from 10% to 50% by weight, more preferably from 10% to 40% by weight, based on the total weight of the composition.

9. 9. The effervescent powder-based composition according to any of the preceding claims, wherein the expandable microspheres are present in an amount of from ≧20% to 70% by weight, more preferably from ≧20% to 50% by weight, based on the total weight of the composition.

10. The effervescent powder-based composition according to any of the preceding claims, wherein the filler is present in an amount of 0 to 70% by weight, more preferably 10% to 60% by weight, based on the total weight of the composition.

11. The effervescent powder base composition according to any of claims 1 to 10, wherein the composition is storage stable at 45°C for at least 7 days.

12. Steps below: (i) forming a powder mixture of (a) one powdered base polymer in an amount of 8 wt.% or more based on the total weight of the powder mixture, (b) one or more expandable microspheres in an amount of 15 wt.% or more based on the total weight of the powder mixture, (c) optionally one filler, and (d) optionally additives, wherein the powder mixture has a moisture content of 3 wt.% or less based on the total weight of the powder mixture; (ii) adding water to the powder mixture obtained in step (i) and mixing to form a composition dispersion, wherein the composition dispersion has a solid content of greater than 58%; and (iii) exposing the composition dispersion to conventional heating or dielectric heating or a combination thereof. A molding method comprising:

13. Steps below: (i) forming a powder mixture of (a) one type of powder base polymer in an amount of 8 wt.% or more based on the total weight of the powder mixture, (b) one type of a plurality of expandable microspheres in an amount of 15 wt.% or more based on the total weight of the powder mixture, (c) optionally one type of filler, and (d) optionally additives, wherein the powder mixture has a moisture content of 3 wt.% or less based on the total weight of the powder mixture; (ii) adding water to the powder mixture obtained in step (i) and mixing to form a composition dispersion, wherein the composition dispersion has a solid content of greater than 58%; (iii) applying the composition dispersion onto a first substrate; (iv) applying a second substrate onto the composition dispersion, thereby forming an article, where the composition dispersion is sandwiched between two substrates; and (v) applying conventional or dielectric heating or a combination thereof to the article. A method of forming an article comprising:

14. 14. The method of claim 13, wherein the first substrate and the second substrate are independently selected from a cellulosic substrate, wood, or a plastic having a melting point above 100°C.

15. 14. The method of claim 13, wherein the cellulosic substrate is fiberboard, chipboard, corrugated cardboard, corrugated board medium, solid bleached board (SBB), solid bleached sulfite board (SBS), solid unbleached board (SLB), white lined chipboard (WLC), kraft paper, kraft board, coated paper, or binder board.

16. 14. The method of claim 13, wherein the composition dispersion is applied in a pattern of a series of dots, stripes, waves, checkerboard, or polyhedral shapes having a substantially flat base.

17. 14. The method of claim 13, further comprising applying an adhesive between the first substrate and the second substrate, the adhesive being a hot melt adhesive.

18. 14. The method of claim 13, wherein the dielectric heating is microwave heating or radio frequency heating or a combination thereof.

19. 14. The method of claim 13, wherein the article is a cup, a food container, a case, a carton, a bag, a box, a lid, an envelope, a wrap, or a clamshell.

Images