TW201638003A - Process for making a fabricated article from polyolefin - Google Patents

Abstract

The present disclosure describes a method for preparing a carbonized article comprising providing a fabricated polyolefin article; crosslinking the fabricated article with a boron-containing species (BCS); stabilizing the fabricated article by air oxidation; and carbonizing the fabricated article. The present disclosure further describes preparing a stabilized article.

Description

Method of manufacturing articles made from polyolefin

The present invention relates to a method of making a carbide member and stabilizing the article.

Previously, carbonaceous articles such as carbon fibers have been produced primarily from polyacrylonitrile (PAN), asphalt or cellulose precursors. The method of making a carbonaceous article begins with the formation of an article (such as a fiber or film) from a precursor. The precursor can be formed into articles using standard techniques for forming or molding the polymer. The article is then stabilized such that the finished article substantially retains shape during the subsequent heat treatment step; without being bound by theory, such stabilization typically involves a combination of oxidation and heating and generally results in defining the precursor of the finished article. Dehydrogenation, ring formation, oxidation and crosslinking. Subsequently, the stabilized article is converted into a carbonaceous article by heating the stabilized article in an inert atmosphere. Although the general steps for producing a carbonaceous article are the same as those for producing a plurality of precursors, the details of those steps vary widely depending on the chemical composition of the precursor selected.

Polyolefins have been investigated as an alternative precursor to carbonaceous articles, but it has proven difficult to achieve suitable and economically viable preparation methods. Of particular interest is the identification of an economical method for preparing carbonaceous articles from polyolefin precursors. For example, maximizing mass retention during the stabilization and carbonization steps is relevant.

The present invention describes a method of preparing a boron-treated carbide member comprising providing a polyolefin article; crosslinking the article with a boron-containing material (BCS); stabilizing the article by air oxidation; And carbonizing the finished article. The invention further describes the preparation of a stable article.

Numerical ranges (eg, "2 to 10") include numbers that define the ranges (eg, 2 and 10) unless otherwise indicated.

Ratios, percentages, parts, and the like are by weight unless otherwise indicated.

Unless otherwise indicated, the crosslinkable functional group content for the polyolefin resin is characterized by the crosslinkable functional group mol%, which is calculated as the number of moles of crosslinkable functional groups divided by the monomers contained in the polyolefin The total number of moles of the unit.

Unless otherwise indicated, "monomer" means a molecule which can be polymerized to constitute a constituent unit of a main structure such as a macromolecule of a polyolefin.

In one aspect, the invention describes a method of producing a carbon-containing article from a polyolefin resin. Any of the methods or process steps described herein can be performed in any order, unless otherwise stated. Polyolefins are a class of polymers produced from one or more olefin monomers. The polymers described herein can be formed from one or more types of monomers. Polyethylene is a preferred polyolefin resin, but other polyolefin resins may be substituted. For example, a polyolefin produced from ethylene, propylene or other alpha-olefins such as 1-butene, 1-hexene, 1-octene, or combinations thereof Also suitable. The polyolefins described herein are typically provided in the form of a resin which is subdivided into agglomerates or granules of suitable size for further melting or solution processing.

The polyolefin resin described herein is subjected to a crosslinking step. In one case, the boron resin is crosslinked using a boron-containing substance (BCS). In one case, the polyolefin resin has been modified to include a crosslinkable functional group suitable for reaction in the presence of BCS to crosslink the polyolefin resin. Any BCS suitable for initiating cross-linking formation in a polyolefin resin is suitable for use. Examples of suitable BCSs include borane, borate, hydrocarbylboronic acid, Acid, boric acid, hydrocarbyl boric acid or Acid esters, boroxanes, amine boranes, boron azepines, borohydrides and derivatives and combinations thereof. In one case, the copolymer is suitable for providing a polyolefin resin having a crosslinkable functional group in which one or more alpha-olefins have been copolymerized with another monomer having a group suitable for acting as a crosslinkable functional group, For example, dienes, carbon monoxide, glycidyl methacrylate, acrylic acid, vinyl acetate, maleic anhydride or vinyltrimethoxydecane (VTMS) are suitable for use in monomers suitable for copolymerization with alpha-olefins. Further, a polyolefin resin having a crosslinkable functional group can also be produced from a poly(α-olefin) which has been modified by grafting a functional group moiety onto a matrix polyolefin, wherein a given polyolefin can be subsequently obtained based on The ability to crosslink selects functional groups. For example, this type of grafting can be achieved by the use of free radical initiators (such as peroxides) and vinyl monomers (such as VTMS, dienes, vinyl acetate, acrylic acid, methacrylic acid, acrylates, and methyl groups). Acrylates (such as glycidyl methacrylate and methacryloxypropyltrimethoxydecane), allylamine, p-aminostyrene, dimethylaminoethyl methacrylate) or via azide The base functionalized molecule (such as 4-[2-(trimethoxydecyl)ethyl)]benzenesulfonyl azide compound) is carried out. The polyolefin resin having a crosslinkable functional group can be produced from a polyolefin resin or is commercially available. Examples of commercially available polyolefin resins having crosslinkable functional groups include SI-LINK sold by The Dow Chemical Company, PRIMACOR sold by The Dow Chemical Company, and EVAL sold by Kuraray. Resin and LOTADER AX8840 sold by Arkema.

The polyolefin resin is processed to form a finished article as described above. The finished article is an article that has been made of a polyolefin resin. The finished article is formed using known polyolefin manufacturing techniques, such as melt or solution spinning to form fibers, film extrusion or film casting or blown film forming methods to form a film, die extrusion or injection molding or compression molding to form More complex shapes, or solution casting. The manufacturing technique is selected based on the desired geometry of the target carbonaceous article and the desired physical properties of the carbonaceous article. For example, where the desired carbonaceous article is a carbon fiber, fiber spinning is a suitable manufacturing technique. As another example, where the desired carbonaceous article is a carbon film, compression molding is a suitable manufacturing technique.

As mentioned above, at least a portion of the polyolefin resin is crosslinked to produce a crosslinked article. In some embodiments, the crosslinking is carried out via chemical crosslinking using BCS. It is contemplated that the cross-linked finished article is cross-linked via a variety of routes, for example, a portion of the cross-linked article can be cross-linked using BCS and the cross-linking of another portion can be made via another cross-linking method known in the art, for example by use. Cross-linking by irradiation or other boron-free mechanism. Thus, in some embodiments, the crosslinked article is a finished article that has been treated with one or more boron containing chemicals to crosslink the crosslinkable functional groups of the polyolefin resin having crosslinkable functional groups. Such chemistries are used to initiate the formation of intramolecular chemical bonds between crosslinkable functional groups or to react with crosslinkable functional groups to form intramolecular chemical bonds, as is known in the art. Chemical cross-linking allows the crosslinkable functional groups to react to form new bonds, forming a defined A bond between various polymer chains of a crosslinked functional group polyolefin resin. The chemical agent that achieves crosslinking is selected based on the type of crosslinkable functional group included in the polyolefin resin; it is known to crosslink a series of different reactive reactions via intermolecular and intramolecular chemical bonds. A suitable chemical agent is selected which is known to be crosslinked to form crosslinkable functional groups present in the article to produce a crosslinked article. For example, without limiting the invention, if the crosslinkable functional group attached to the polyolefin is a vinyl group, suitable chemical agents include free radical initiators such as peroxides or azo-bisnitriles. Compounds such as dicumyl peroxide, benzamidine peroxide, tert-butyl peroctoate, azobisisobutyronitrile and the like. If the crosslinkable functional group attached to the polyolefin is an acid such as a carboxylic acid or an anhydride or ester or a glycidoxy group, suitable chemical agents may be compounds containing at least two nucleophilic groups, including dinucleophilic Reagents such as diamines, diols, dithiols such as ethylenediamine, hexamethylenediamine, butanediol or hexanedithiol. Compounds containing more than two nucleophilic groups such as glycerol, sorbitol or hexamethylenetetramine may also be used. Mixed dinucleophiles or high nucleophiles (which contain at least two different nucleophilic groups, such as ethanolamine) may also be suitable chemical agents. If the crosslinkable functional group attached to the polyolefin is a monoalkoxyalkylene, dialkoxyalkylene or trialkoxyalkylene group, water and Lewis acid or Bronsted acid or A base catalyst can be used as a suitable chemical agent. For example, without limiting the invention, the Lewis acid or Bruce's acid or base catalyst comprises an aryl sulfonic acid, sulfuric acid, hydroxide, zirconium alkoxide or tin reagent.

Cross-linked articles are generally preferred to ensure that the finished article retains its shape at the elevated temperatures required for subsequent processing steps. In the case of no crosslinking, the polyolefin resin is usually softened, melted or deformed or decomposed at a high temperature. Crosslinking increases the thermal stability of the finished article.

The cross-linked articles are heated in an oxidizing environment to produce a stable finished article. In some embodiments, the temperature for stabilizing the crosslinked article is at least 120 ° C, preferably at least 190 ° C. In some embodiments, the temperature for stabilizing the crosslinked article is no more than 400 ° C, preferably no more than 300 ° C. In one case, the cross-linked article is introduced into a heating chamber that has reached the desired temperature. In another case, the finished article is introduced into a heating chamber at or near ambient temperature, which is then heated to the desired temperature. In some embodiments, the heating rate is at least 1 °C/minute. In other embodiments, the heating rate does not exceed 15 ° C / minute. In yet another case, the chamber is gradually heated, for example, by heating the chamber to a first temperature for a period of time (such as 120 ° C for one hour), and then to a second temperature for a period of time (such as 180 ° C for one hour). And rise to the holding temperature for the third time (such as 250 ° C for 10 hours). Depending on the size of the article being made, the stabilization method involves maintaining the crosslinked article at a given temperature for a period of up to 100 hours. The stabilization process produces a boron-treated stabilized article that is used for the precursor of the carbonaceous article. Without being bound by theory, the stabilizing process oxidatively crosslinks the articles into articles and changes the hydrocarbon structure, which increases the crosslink density while reducing the hydrogen/carbon ratio of the crosslinked articles. In one case, the stabilization process introduces boron into the hydrocarbon structure by processing the article with boron during the stabilization process.

Unexpectedly, it has been found that the quality retention of stable articles subsequently produced by BCS modification in an oxidizing environment is found. Unexpectedly, it has been found that the quality retention of the stabilized carbonaceous articles subsequently produced by the BCS modification is included in the finished article during the stabilization step. It has also been found that treatment of crosslinked articles with boron-containing materials improves the form-retention of subsequently produced carbonaceous articles.

In another aspect, the invention is described by a polyolefin precursor (tree The boron-formed stabilized article formed by the lipid. In one case, the boron-treated stabilized article is formed according to the methods described herein.

In yet another aspect, a carbonaceous article and a method of making the same are provided. Carbonaceous articles are carbon-rich articles; carbon fibers, carbon flakes, and carbon films are examples of carbonaceous articles. Carbonaceous articles have many applications, such as carbon fiber, which is commonly used to reinforce composite materials, such as for carbon fiber reinforced epoxy resin composites, and carbon disks or pads for high performance braking systems.

The carbonaceous articles described herein are prepared by carbonizing a stable article by heat treating a boron treated stabilized article in an inert environment. The inert environment is an environment surrounding the boron-treated stable article and exhibiting less reactivity with carbon at a high temperature, preferably a high vacuum or an oxygen-depleted atmosphere, more preferably a nitrogen atmosphere or an argon atmosphere. It should be understood that traces of oxygen may be present in an inert atmosphere. In one case, the temperature of the inert environment is 600 ° C or higher. Preferably, the temperature in the inert environment is 800 ° C or higher. In one case, the temperature of the inert environment does not exceed 3000 °C. In one case, the temperature is from 1400 ° C to 2400 ° C. Temperatures at or near the upper end of the range will produce graphite articles, while temperatures at or near the lower end of the range will produce carbon articles.

To prevent foaming or damage to the finished article during carbonization, it is preferred to heat the inert environment in a gradual or stepwise manner. In one embodiment, the boron treated stabilized article is introduced into a heating chamber containing an inert environment at or near ambient temperature, followed by heating the chamber for a period of time to achieve the desired final temperature. The heating schedule may also include one or more holding steps at a final temperature or intermediate temperature or a programmed cooling rate for a specified period of time prior to removal of the item from the chamber.

In yet another embodiment, the chamber containing the inert environment is subdivided into a plurality of zones, each maintained at a desired temperature by suitable control means, and passed from one zone to the appropriate via a suitable transport mechanism, such as a motorized belt. A stepwise manner in the next zone heats the stabilized article that has been treated with boron. In the case where the boron-treated stabilized article is a fiber, the transport mechanism can be to apply traction to the fiber at the exit of the carbonization process while controlling the tension in the stabilized fiber at the inlet. Some embodiments of the invention will now be described in detail in the following examples.

In the examples, the total mass yield is calculated as the product of the oxidized mass yield and the carbonized mass yield. PHR refers to the number of parts per part of resin (quality basis). MI refers to the melt index, which is a measure of the melt flow rate. Weight% means the number of parts per 100 parts, based on mass. PE means polyethylene. BA refers to boric acid. Determination of the yield of measurement

Oxidation mass yield:

Carbonization mass yield:

Total mass yield: Y _M = Y _O Y _C

Total mass yield (carbonaceous mass per PE of initial mass):

Wherein m _PE is the initial mass of polyethylene; m _OX is the mass remaining after oxidation; m _CF is the mass remaining after carbonization; and M% _PE is the mass % of polyethylene in the initially formed article.

Soxhlet extraction is a method for determining the gel content and expansion ratio of crosslinked ethylene plastics. As used herein, the standard test method for Determination of Gel Content and Swell Ratio of Crosslinked Ethylene Plastics is used in accordance with ASTM Standard D2765-11 "Standard Test Methods for Determination of Gel Content and Swell Ratio of Crosslinked Ethylene Plastics". Extraction. In the method used, weigh 0.050g and 0.500g The cross-linking between the articles was made and placed in a cellulose-based sleeve, which was then placed in a Soxhlet extraction apparatus with a sufficient amount of xylene. Soxhlet extraction with refluxing xylene is continued for at least 12 hours. After the extraction, the sleeve was removed and the cross-linked articles were dried in a vacuum oven at 80 ° C for at least 12 hours and then weighed, thereby providing a Soxhlet-treated article. The gel content (%) was then calculated from the weight ratio (Soxhed article) / (crosslinked article).

Example 1

The ethylene/octene copolymer (density = 0.941 g/cm ³ ; MI = 34 g/10 min, 190 ° C / 2.16 kg) was reactively extruded with vinyl trimethoxydecane (VTMS) to form VTMS grafted ethylene / Octene copolymer (MI = 19 g/10 min, 190 ° C / 2.16 kg; 1.4 wt% grafted decane content, determined by ¹³ C NMR) precursor resin. The VTMS grafted precursor resin was melt spun to form fibers having the following characteristics: 1573 filaments, 1945.8 total denier, 2.25 gf/den, 12.17% elongation at break. The fiber bundle was continuously treated in a vessel containing a solution of isopropyl alcohol having 5% by weight of boric acid. The fiber residence time in the solution was 5 seconds. The treated fibers were dried and cured for 3 days. The fibers were then moisture cured at 80 ° C (100% relative humidity) for 1-5 days as reported in Table 1. The gel fraction was determined by Soxhlet extraction to be 42.9-55.2%. The full results are reported in Table 2.

Boric acid crosslinked fibers were oxidized and carbonized using a thermogravimetric analysis (TGA) instrument using the conditions outlined in Table 3. The temperature slope was maintained at 10 ° C / min for continuous oxidation and carbonization. Table 4 reports the mass retained during air oxidation and the final mass yield after both oxidation and carbonization treatments.

Example 2

The ethylene/octene copolymer (density = 0.941 g/cm ³ ; MI = 34 g/10 min, 190 ° C / 2.16 kg) was reactively extruded with vinyl trimethoxydecane (VTMS) to form VTMS grafted ethylene / Octene copolymer (MI = 19 g/10 min, 190 ° C / 2.16 kg; 1.4 wt% grafted decane content, determined by ¹³ C NMR) precursor resin. The VTMS grafted precursor resin was melt spun to form fibers having the following characteristics: 1573 filaments, 1945.8 total denier, 2.25 gf/den, 12.17% elongation at break. The fiber bundle was continuously treated in a vessel containing a solution of isopropyl alcohol having 5% by weight of boric acid. The fiber residence time in the container was 5 minutes. The treated fibers were dried and cured for 3 days. The fibers were then moisture cured at 80 ° C (100% relative humidity) for 1-5 days as reported in Table 5. The gel fraction was determined by Soxhlet extraction to be 42.4-54.1%. The full results are reported in Table 6.

The resulting boric acid crosslinked fibers were oxidized and carbonized using a thermogravimetric analysis (TGA) instrument using the conditions outlined in Table 7. The temperature slope was maintained at 10 ° C / min for continuous oxidation and carbonization. Table 8 reports the quality retained during air oxidation and the final mass yield after both oxidation and carbonization treatments.

Example 3

The three fragments (A, B and C) prepared and crosslinked according to Example 1 were treated with a 15% by weight solution of boric acid in methanol for the various times reported in Table 9. After treatment with the boric acid solution, the fibers were dried overnight in air under ambient conditions. The dried, boric acid treated fibers were then subjected to heat treatment (80 ° C) overnight in a vacuum oven. The relative changes in fiber quality and quality before and after boric acid treatment are reported in Table 10.

The heat treated boric acid treated crosslinked fibers were oxidized and carbonized using a thermogravimetric analysis (TGA) instrument using the conditions outlined in Table 11. The temperature slope was maintained at 10 ° C / min for continuous oxidation and carbonization. Table 12 reports the mass retained during air oxidation and the final mass yield after both oxidation and carbonization treatments.

Claims (10)

A method of preparing a carbide member, comprising: (a) providing a polyolefin resin; (b) forming a finished article from the polyolefin resin; and (c) crosslinking the finished article with a boron-containing substance (BCS) (d) stabilizing the article by air oxidation; and (e) carbonizing the article. The method of claim 1, wherein the BCS comprises borane, borate, hydrocarbylboronic acid, Acid, boric acid, hydrocarbyl boric acid or Acid esters, boroxanes, amine boranes, boron azepines, borohydrides and derivatives and combinations thereof. The method of claim 1, wherein the method further comprises treating the crosslinked article prepared in step (c) with BCS. The method of any one of claims 1 to 3, wherein the step (d) comprises heating the crosslinked article at 120 ° C or higher. The method of any one of claims 1 to 4, wherein the step (b) comprises fiber spinning, film extrusion casting, blown film processing, die pressing through a die, Injection molding, solution casting or compression molding converts the polyolefin resin into a finished article. A method of preparing a boron-treated carbide member, comprising: (a) providing a polyolefin article; (b) crosslinking the article with a boron-containing material (BCS); (c) oxidizing by air Stabilizing the finished article; and (d) carbonizing the finished article. The method of claim 6, wherein the BCS comprises borane, borate, hydrocarbylboronic acid, Acid, boric acid, hydrocarbyl boric acid or Acid esters, boroxanes, amine boranes, boron azepines, borohydrides and derivatives and combinations thereof. The method of claim 6, wherein the method further comprises treating the crosslinked article prepared in step (b) with BCS. The method of any one of clauses 6 to 8, wherein the step (c) comprises heating the crosslinked article at 120 ° C or higher. A method of preparing a stable article, comprising: (a) providing a polyolefin-made article; (b) crosslinking the article with a boron-containing material (BCS); and (c) stabilizing the air by oxidation Made of objects.