TW202400700A - Physically foamed polymer, method of manufacturing the same, and eco-friendly sandal in one piece including the same - Google Patents

Abstract

The present invention relates to a physically foamed polymer, a method of manufacturing the same and eco-friendly sandal in one piece including the same. In this method, a polyolefin material can be subjected to a molding process with physical foam, in which the polyolefin material can include a recycled EVA foaming material, and the injection molding process with physical foam excludes treatments of cross-linking. The physically foamed polymer can be made and applied to an eco-friendly sandal in one piece having low cost and properties of light weight, anti-slip and foams with uniform porosity.

Description

Polymer physical foam and its manufacturing method and integrated environmentally friendly slippers containing the same

The present invention relates to a polymer foam, in particular to a polymer physical foam that adds a high amount of recycled EVA foam material and omits chemical cross-linking treatment, its manufacturing method, and an integrally molded environmentally friendly product containing it.

Ethylene vinyl acetate (EVA) copolymer foam material has good flexibility, elasticity, chemical resistance, colorability and light weight. In recent years, it has become a popular choice for leisure sports products (such as soles, insoles, yoga mats etc.) mainstream. However, EVA foam material waste is mostly destroyed by burning. The toxic gases and thick smoke produced during combustion not only harm the environment and human body, but also the waste after destruction cannot be reused. There is a need for improvement.

One of the conventional solutions is to recycle the remaining EVA unfoamed materials, crush them appropriately, heat-melt granulate them, and mix them with other unfoamed rubber materials for a chemical foaming process. Then made into foam material. However, this type of product can only recycle and process the remaining EVA unfoamed material. The amount of EVA unfoamed material remaining is very limited. It is impossible to recycle and process the foamed EVA material. It can only use the chemical foaming process. Subsequent It is not easy to make one-piece footwear products, and it cannot meet the requirements of light weight, uniform cells and low cost. Another solution is to recycle the foamed materials, crush them appropriately, and heat-melt them at high temperature (200°C) to press out the sheets. However, the foamability of this type of product has deteriorated, and it can only be layered with fresh foam materials before foaming and molding, which cannot meet the requirements of light weight and uniformity of cells.

In view of this, there is an urgent need to provide a method of recycling EVA foam materials and products thereof, so as to improve various problems of the conventional recycling process of EVA foam materials.

Therefore, one aspect of the present invention is to provide a method for manufacturing a polymer physical foam, which includes performing a physical foaming molding process on a polyolefin material, wherein the polyolefin material includes recycled EVA foam material, and the physical foaming molding process The manufacturing process excludes cross-linking treatment, thereby obtaining a polymer physical foam.

Another aspect of the present invention is to provide a polymer physical foam, which is prepared by the above method and can be used to prepare environmentally friendly slippers that are low-cost, lightweight, non-slip and have uniform cells.

Another aspect of the present invention is to provide an integrated flip-flop, which includes the above-mentioned polymer physical foam.

Another aspect of the present invention is to provide an environmentally friendly flip-flop, which includes the above-mentioned polymer physical foam.

Another aspect of the present invention is to provide an environmentally friendly clip-on environmentally friendly slipper, which is an integrated structure composed of a sole and a herringbone lug connected to the sole.

According to the above aspect of the present invention, a method for manufacturing a polymer physical foam is proposed. In one embodiment, the method includes providing a polyolefin material, wherein the polyolefin material includes 0 to 50 parts by weight of the first ethylene vinyl acetate (EVA) copolymer based on 100 parts by weight of the total weight of the resin component, and the first The EVA copolymer is an unmodified EVA copolymer; and 50 to 100 parts by weight of a second EVA copolymer, wherein the second EVA copolymer is a modified EVA copolymer and/or recycled EVA foam material, and recycled EVA foam The material can be, for example, recycled EVA physical foam material. Next, in the presence of a physical foaming agent, the aforementioned polyolefin material is subjected to a physical foaming molding process to obtain a polymer physical foam. The physical foaming agent can be, for example, nitrogen. The physical foaming agent is in the polyolefin material. The usage amount can be, for example, 0.5 to 2%, and the physical foaming molding process excludes cross-linking treatment.

In the above embodiment, the vinyl acetate (VA) content of the unmodified EVA copolymer can be, for example, 7 to 33%.

In the above embodiments, the aforementioned modified EVA copolymers may include, but are not limited to, acid-modified EVA copolymers, anhydride-modified EVA copolymers, acid-acrylate modified EVA copolymers, and anhydride-acrylate modified EVA copolymers. and any combination of the above.

In the above embodiments, the aforementioned polyolefin material may optionally include 1 to 10 parts by weight of a foaming assistant, and the foaming assistant may include zinc oxide.

In the above embodiments, the polyolefin material may optionally include 1 to 10 parts by weight of a filler, and the filler may include titanium dioxide, talc and/or calcium carbonate.

In the above embodiments, the physical foaming molding process can be performed using, for example, a single-station supercritical foaming equipment.

According to another aspect of the present invention, a polymer physical foam is proposed, which is prepared by the above method. In one embodiment, the apparent density of the polymer physical foam can be, for example, less than 0.25 g/cm ³ , the rebound strength can be, for example, greater than 35%, the compression deflection can be, for example, less than 80, the anti-slip coefficient can be, for example, at least 0.4, and Rebound strength can be measured, for example, according to ASTM D2632.

According to another aspect of the present invention, an integrated flip-flop is proposed, which includes the above-mentioned polymer physical foam.

According to yet another aspect of the present invention, an environmentally friendly flip-flop is proposed, which includes the above-mentioned polymer physical foam.

According to yet another aspect of the present invention, an environmentally friendly slipper is proposed, which is an integral structure composed of a sole and a herringbone lug connected to the sole. In one embodiment, the apparent density of the eco-friendly slippers can be, for example, less than 0.25 g/cm ³ , the resilience can be, for example, greater than 35%, the compression deflection can be, for example, less than 80, the dry anti-slip coefficient is at least 0.5, and the wet anti-slip coefficient is at least 0.4, and the resilience performance can be measured, for example, according to ASTM D2632.

The polymer physical foam and its manufacturing method of the present invention are applied to the integrated molding of environmentally friendly slippers containing the same. The polyolefin material includes recycled EVA foam material, and the physical foaming molding process excludes cross-linking treatment, thereby obtaining high-quality Molecular physical foam can be used to prepare environmentally friendly slippers that are low-cost, lightweight, non-slip and have uniform cells.

Through the following detailed description and with reference to the accompanying drawings, embodiments of the present invention are described in detail below. The same figure numbers used in the drawings and instructions refer to the same or similar parts as much as possible.

All documents cited herein by reference are to the same extent as if each individual document or patent application was specifically and individually incorporated by reference by reference. If the definition or usage of a term in a cited document is inconsistent or contrary to the definition of the term herein, the definition of the term here shall apply and not the definition of the term in the cited document.

For the purpose of interpreting the specification, the following definitions will apply and, where appropriate, singular nouns will also include the plural and vice versa. Additional definitions are set forth throughout the detailed description.

Unless the context is inappropriate, "a/an" and "the/said" as used herein are defined as "one or more" and include the plural form.

As mentioned above, the present invention provides a polymer physical foam and a manufacturing method thereof, as well as an integrally molded environmentally friendly slipper containing the polymer physical foam, which includes mixing a recycled polymer physical foam and an unmodified EVA copolymer, In the presence of a foaming agent, the polyolefin material is subjected to a physical foaming molding process to obtain a polymer physical foam. In this way, not only the waste EVA foam materials are effectively recycled and reused, but the polymer physical foams produced are low-cost, lightweight, non-slip, have uniform cells, and more effectively reduce carbon emissions.

The "polymer physical foam" mentioned here can include, but is not limited to, products made from polyolefin materials containing recycled polymer physical foam through a physical foaming molding process. Please refer to FIG. 1 , which is a partial flow chart of a method 100 for manufacturing a polymer physical foam according to an embodiment of the present invention. In one embodiment, as shown in step 101 of FIG. 1 , first, a polyolefin material is provided, which may include a first ethylene vinyl acetate (EVA) copolymer and a second EVA copolymer.

In some examples, the first EVA copolymer may include but is not limited to an unmodified EVA copolymer, in which the vinyl acetate (VA) content of the unmodified EVA copolymer is not particularly limited and may be, for example, 7 to 33%; However, in other examples, the VA content of the unmodified EVA copolymer may be, for example, 18 to 26%. Commercially available products can be used as the first EVA copolymer, such as but not limited to Taisoxene model 7470K (VA content 26%, MI _2.16 is 5.5 g/10 minutes), Taisoxene model 7350M (VA content 18%, MI _2.16 is 2.5 g/10 minutes), etc., but the present invention is not limited to these examples.

In other examples, the second EVA copolymer may include, but is not limited to, modified EVA copolymer and/or recycled EVA foam. In the above examples, modified EVA copolymers may include, but are not limited to, acid-modified EVA copolymers, anhydride-modified EVA copolymers, acid-acrylate modified EVA copolymers, anhydride-acrylate modified EVA copolymers, and the like. Any combination. Modified EVA copolymers can be commercially available products, such as but not limited to Formosa resin model EF-50 (MI _2.16 is 2 g/10 minutes), EF-40 (MI _2.16 is 4 g/10 minutes), but the present invention Not limited to what is shown here.

In the case where a modified EVA copolymer is used as the second EVA copolymer, 1 to 10 parts by weight of a foaming assistant can be optionally added to the above polyolefin material. Generally speaking, foaming assistants can be used to reduce the decomposition temperature of the foaming agent, which can include but are not limited to zinc oxide, zinc stearate, zinc nitrate, zinc phthalate, zinc carbonate, phosphorus trichloride salt, Tribasic zinc sulfate, and other inorganic salts; fatty acid zinc soap, fatty acid lead soap, fatty acid cadmium soap, and other metal soaps; boric acid, oxalic acid, succinic acid, adipic acid, and other acids; urea, ethanolamine, glucose, Glycerin etc. The above-mentioned polyolefin material can optionally add 1 to 10 parts by weight of filler. Generally speaking, fillers may include, but are not limited to, talc, magnesium carbonate, magnesium silicate, calcium carbonate, clay, mica, sulfate-containing salts, magnesium hydroxide, and the like.

In the above embodiment, based on the total weight of the resin component being 100 parts by weight, the content of the first EVA copolymer may be, for example, greater than 0 to 50 parts by weight, and the content of the second EVA copolymer may be, for example, 50 to less than 100 parts by weight.

In the above example of the second EVA copolymer, the recycled EVA foam material may also be waste EVA physical foam material. Among the aforementioned polyolefin materials, the ratio of unmodified EVA copolymer to recycled EVA foam material is not particularly limited, but the content of recycled EVA foam material is preferably not less than 50 parts by weight. It should be added that when the above-mentioned second EVA copolymer is recycled EVA foam material, not only the proportion of recycled material is as high as more than 50 parts by weight, but also the use of foaming aids and/or fillers can be omitted, so the cost can be effectively reduced. .

It should be noted here that if the aforementioned polyolefin material does not contain the second EVA copolymer, or the content of the second EVA copolymer of the aforementioned polymer is less than 50% by weight, the prepared polymer physical foam cannot effectively reduce the carbon emission.

As shown in step 103 of Figure 1, next, in the presence of a physical foaming agent, the polyolefin material is subjected to a physical foaming molding process to obtain a polymer physical foam (as shown in step 105), where the physical The amount of foaming agent used in the polyolefin material can be, for example, 0.1 to 2%. The physical foaming agent can include but is not limited to nitrogen, and the physical foaming molding process excludes cross-linking treatment.

In the above embodiments, the aforementioned physical foaming molding process is not particularly limited, and may include but is not limited to, for example, a physical injection molding process or a physical impregnation molding process. Conventional equipment (such as a single-station supercritical injection foaming equipment) may also be used. Or single-station supercritical impregnation foaming equipment). Secondly, the above equipment can also be used in batch or continuous processes. In short, the polyolefin material can be first subjected to conventional granulation treatment, and then injected into the mold of the above-mentioned equipment together with the physical foaming agent, and the physical foaming molding process can be carried out using conventional parameter conditions. Taking the physical injection molding process as an example, polyolefin material particles together with a physical foaming agent can be injected into the mold of the above equipment at a temperature of, for example, 200 to 250°C, at an injection speed of, for example, 100 to 150 mm/s. High-pressure impregnation step, and after cooling for a period of time, the parison is obtained. Then, the parison is placed in the finished mold, and a 1:1 in-mold foaming step is performed at a temperature of, for example, 20 to 50° C. for, for example, 8 to 18 minutes, to obtain a polymer physical foam. The above-mentioned granulation treatment, high-pressure impregnation step and in-mold foaming step are also well known to those with ordinary knowledge in the technical field to which the present invention belongs, and therefore will not be described in detail. The apparent density of the polymer physical foam thus obtained can be, for example, less than 0.25 g/cm ³ , the rebound strength can be, for example, greater than 35%, the compression deflection can be, for example, less than 80, the anti-slip coefficient is at least 0.4, and the rebound strength Measured in accordance with ASTM D2632.

It should be added that the polymer physical foam thus obtained can be used to make various environmentally friendly slippers, such as one-piece environmentally friendly slippers, environmentally friendly flip-flops, etc. Please refer to Figures 2 and 3, which respectively illustrate a top view (Figure 2) and a bottom side view (Figure 3) of the one-piece eco-friendly slipper according to an embodiment of the present invention. In this embodiment, the eco-friendly slippers 200 can be an integral structure composed of a sole 201 and a herringbone lug 211 connected to the sole 201 . The apparent density of the eco-friendly slippers 200 can be, for example, less than 0.25 g/cm ³ , so it has lightweight characteristics. Secondly, the rebound strength of the eco-friendly slippers 200 can be, for example, greater than 35%, the compression deflection can be, for example, less than 80, the anti-slip coefficient is at least 0.4, and the rebound strength is measured according to ASTM D2632. The "anti-slip coefficient" mentioned here may include but is not limited to a dry anti-slip coefficient and a wet anti-slip coefficient, wherein the dry anti-slip coefficient may be, for example, at least 0.5, and the wet anti-skid coefficient may be, for example, at least 0.4. However, in other specific examples, the dry anti-slip coefficient of the eco-friendly slippers may be, for example, at least 0.6, and the wet anti-slip coefficient may be, for example, at least 0.4. The anti-slip coefficient can be measured using various conventional methods, which will not be described further.

As shown in Figure 2, the herringbone lug 211 of this environmentally friendly slipper 200 is composed of a toe-clip portion 211a, an inner shoe lug 211b, and an outer shoe lug 211c. The toe-clip portion 211a can be connected to the wearing surface 203 of the sole 201. The inner lug 211b and the outer lug 211c are connected to the outer side 201a and the inner side 201b of the sole 201 respectively.

Furthermore, as shown in FIGS. 2 and 3 , the eco-friendly slippers 200 have an anti-slip function, which is provided by the anti-slip structure of the wearing surface 203 of the sole 201 and the lower surface 309 of the sole 301 . In some examples, as shown in FIG. 2 , the anti-slip structure of the wearing surface 203 can be, for example, a plurality of protrusions 205 and concave surfaces 207 to facilitate the user to provide anti-slip and comfortable functions for the soles of the feet when wearing. As shown in Figure 3, the lower surface 309 of the sole 301 of this environmentally friendly slipper 300 is provided with a plurality of anti-slip structures 320, including anti-slip textures 323, anti-slip textures 325, and anti-slip textures 327. The above forms are not limited, and can be, for example, But it is not limited to geometric patterns of anti-slip textures, high-density staggered linear anti-slip textures, high-density interlaced linear anti-slip textures with a concave center, low-density short-line staggered anti-slip textures, or any combination of the above. Secondly, there are narrow grooves 321 and wide grooves 329 between the anti-slip lines 323, 325 and 327, which are beneficial to drainage and walking. As shown in Figure 3, in addition to connecting the shoe ears 211 on the outer side 301a and the inner side (not shown) of the eco-friendly slipper 300, there are also a plurality of surfaces on the outer side 301a, the inner side and the front and rear sides (not shown). Cushioning texture 335 to provide additional cushioning (or rebound) function and reduce pressure on the foot when walking.

The polymer physical foam of the present invention not only increases the usage of recycled EVA physical foam materials, but also eliminates cross-linking treatment in the physical foaming molding process. The polymer physical foam obtained thereby can be used to prepare low-cost, One-piece eco-friendly slippers that are lightweight, non-slip and have uniform cells.

Several examples are used below to illustrate the application of the present invention, but they are not intended to limit the present invention. Those with ordinary knowledge in the technical field of the present invention can make various changes and modifications without departing from the spirit and scope of the present invention. polish. Example 1: Preparation and recycling of EVA foam materials

First, after cleaning the surface of the recycled EVA physical foam, use commercially available grinding equipment to coarsely crush it into recycled EVA foam material (average particle size is about 5 to 10 mm). Example 2: Preparation of environmentally friendly slippers made of polymer physical foam Preparation Example 1

First, according to Table 1, add the first EVA copolymer and the second EVA copolymer, add a foaming aid (1phr, ZnO) and a filler (1phr, _TiO2 ), mix them evenly, and perform conventional granulation treatment. Finally, together with nitrogen (0.7%), at a temperature of 225°C, the gas-containing raw material is injected into the finished mold of a commercially available single-station supercritical injection foaming equipment at an injection speed of 120 mm/s. A 1:1 in-mold foaming step was carried out for 13 minutes at a temperature of C to obtain a polymer physical foam and conduct subsequent evaluation. Preparation Examples 2 to 7 and Comparative Example 1

Preparation Examples 2 to 7 and Comparative Example 1 are prepared according to Table 1 using the same process as Preparation Example 1. The difference is that the polyolefin materials of Preparation Examples 2 to 7 and Comparative Example 1 use ingredients of different specifications or different usage amounts. , Preparation Example 2, Preparation Example 5, and Preparation Example 7 added 1 phr of foaming aid (ZnO) and 2 phr of filler (TiO ₂ ), and the second EVA copolymer of Preparation Example 3, Preparation Example 4, and Preparation Example 6 was used. Example 1 recovers EVA foam material but does not add foaming aids and fillers. Preparation Example 5 has the same composition as Preparation Example 1 but adds toner. Comparative Example 1 does not use the second EVA copolymer and does not add foaming agent. Foaming aids and fillers.

Table 1 Example 3: Evaluating the physical properties of polymer physical foam

As shown in Table 1, the apparent density of the polymer physical foams of Preparation Examples 1 to 7 is 0.18 g/cm ³ to 0.22 g/cm ³ , the rebound strength is greater than 35%, the compression deflection is less than 80, and the melt index (MI _2.16 g/10 minutes) is 2.8 to 4.5, yield strength is 15.5 to 17.2 kgf/cm ² , tensile strength is 180 to 205 kgf/cm ² , elongation is 712% to 786%, and dry anti-slip coefficient is 0.62 to 0.66, and the wet anti-slip coefficient is 0.49 to 0.51, where the rebound strength is measured in accordance with ASTM D2632. In comparison, the rebound strength of the polymer physical foam in Comparative Example 1 is not more than 35%, the compression deflection is more than 80, and it does not contain recycled EVA physical foam materials. Furthermore, the polymer physical foam of Comparative Example 1 can only be molded in a flat mold and cannot be molded in a Y drag mold to obtain a finished product.

In addition, the microstructure of the polymer physical foams of Preparation Examples 1 to 7 and Comparative Example 1 was examined using a commercially available electron scanning microscope. It was found that the pore distribution of the polymer physical foams of Preparation Examples 1 to 3 and 5 to 7 was relatively uniform. , the pores of the polymer physical foam of Preparation Example 4 are relatively uneven.

In summary, the above-mentioned specific specifications of EVA copolymers, specific recycled EVA physical foam materials, and specific physical foaming molding processes or specific evaluation methods are only used to illustrate the polymer physical foam and its manufacture of the present invention. Methods and integrated environmentally friendly slippers containing this. However, those with ordinary knowledge in the technical field to which the present invention belongs should understand that other specifications of EVA copolymers, other recycled EVA physical foam materials, and other physical foam molding processes can be used without departing from the spirit and scope of the present invention. Or other evaluation methods can also be used for polymer physical foam and its manufacturing method and the one-piece environmentally friendly slippers containing it, and are not limited to the above. For example, other specifications or other amounts of recycled EVA physical foaming materials or other physical foaming agents can also be used without affecting the light weight, anti-slip, and cell uniformity, without further details.

It can be seen from the above embodiments that the polymer physical foam and its manufacturing method of the present invention and the integrated environmentally friendly slippers containing the polymer physical foam have the advantage that the polyolefin material contains recycled EVA foam material, and the physical foam injection molding process is eliminated. Cross-linking treatment, the polymer physical foam obtained thereby can be used to prepare one-piece environmentally friendly slippers with low cost, lightweight, non-slip and uniform cells.

Although the present invention has been disclosed above in terms of several specific embodiments, various modifications, changes and substitutions may be made to the foregoing disclosure, and it should be understood that, in some cases, without departing from the spirit and scope of the present invention, Certain features of embodiments of the invention may be employed without corresponding use of other features. Therefore, the spirit and scope of the claims of the present invention should not be limited to the above illustrated embodiments.

100: Method 101, 103, 105: Step 200, 300: Environmentally friendly slippers 201, 301: Sole 201a, 301a: Outside 201b: Inside 203, 303: Wearing surface 205: Protrusion 207: Concave surface 211, 311: Herringbone shoe ear 211a: Foot clamping part 211b: Inner shoe ear 211c: Outer Ear 309: Lower surface 320: Anti-slip structure 321, 329: Grooves 323, 325, 327: Anti-slip texture 335: Buffer texture

In order to make the above and other objects, features, advantages and embodiments of the present invention more clearly understood, the attached drawings are described in detail as follows: [Fig. 1] illustrates polymer physical foaming according to one embodiment of the present invention. Partial flow chart of the manufacturing method of the body. [Fig. 2] is a top view of an integrated eco-friendly slipper according to an embodiment of the present invention. [Fig. 3] shows a lower side view of the one-piece eco-friendly slipper according to one embodiment of the present invention.

100:Method

101,103,105: Steps

Claims (10)

A method for manufacturing polymer physical foam, including: A polyolefin material is provided, wherein the polyolefin material contains 100 parts by weight based on the total weight of a resin component: Greater than 0 to 50 parts by weight of a first ethylene vinyl acetate (EVA) copolymer, wherein the first EVA copolymer includes an unmodified EVA copolymer; and 50 to less than 100 parts by weight of a second EVA copolymer, wherein the second EVA copolymer includes a modified EVA copolymer and/or a recycled EVA foam material, and the recycled EVA foam material is a recycled EVA physical foam; and In the presence of a physical foaming agent, the polyolefin material is subjected to a physical foaming injection molding process to obtain the polymer physical foam, wherein the physical foaming agent is nitrogen, and the physical foaming agent is in the The usage amount of one of the polyolefin materials is 0.5 to 2%, and the physical foam injection molding process excludes a cross-linking process. The manufacturing method of polymer physical foam as described in claim 1, wherein the vinyl acetate (VA) content of the unmodified EVA copolymer is 7 to 33%. The manufacturing method of polymer physical foam as described in claim 1, wherein the modified EVA copolymer is selected from the group consisting of acid-modified EVA copolymer, anhydride-modified EVA copolymer, acid-acrylate modified EVA A group consisting of copolymers, anhydride-acrylate modified EVA copolymers and any combination thereof. The method for manufacturing a polymer physical foam as claimed in claim 3, wherein the polyolefin material further includes 1 to 10 parts by weight of a foaming aid, and the foaming aid includes zinc oxide. The method for manufacturing a polymer physical foam according to claim 3, wherein the polyolefin material further includes 1 to 10 parts by weight of a filler, and the filler includes titanium dioxide, talc and/or calcium carbonate. The manufacturing method of polymer physical foam as described in claim 1, wherein the physical foaming injection molding process is carried out using a single-station supercritical injection foaming equipment. A polymer physical foam, which is produced by the method described in any one of claims 1 to 6, wherein one of the apparent densities of the polymer physical foam is less than 0.25 g/cm ³ and one The rebound strength is greater than 35%, the compression deflection is less than 80, the wet anti-slip coefficient is at least 0.4, and the rebound strength is measured in accordance with ASTM D2632. An integrated environmentally friendly slipper, including the polymer physical foam as described in claim 7. An environmentally friendly flip-flop slippers, including the polymer physical foam described in claim 7. An environmentally friendly slipper is an integrated structure composed of a sole and a herringbone lug connected to the sole. The environmentally friendly slipper has an apparent density of less than 0.25 g/cm ³ , a rebound strength of greater than 35%, and a compression distortion. Less than 80, a dry anti-slip coefficient of at least 0.5 and a wet anti-slip coefficient of at least 0.4, and the rebound strength is measured in accordance with ASTM D2632.

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