CN1116331C - On-line solid polymerization of polyethylene glycol terephthalate chips used for making plastic strapping tape - Google Patents

Abstract

A process for preparing a PET flake mixture for use in connection with the fabrication of high-performance plastic strapping comprises the steps of initially collecting post-consumer and non-post-consumer PET materials having an initially wide range of relatively low intrinsic viscosity (IV) values with a relatively low average intrinsic viscosity (IV) value, and processing the same through solid state polymerization (SSP) so as to obtain a wide range of relatively high intrinsic viscosity (IV) values with a relatively high average intrinsic viscosity (IV) value. The initially collected materials are chopped into flakes and chunks, are able to be substantially increased in intrinsic viscosity (IV) values and within a relatively short period of time.

Description

Be used to make the online solid-state polymerization of the polyethylene terephthalate fragment of plastic strapping tape

This patent application is the U.S. Patent application 08/794th of people such as Donald Van Erden in application on February 3rd, 1997, No. 538 part continuation application, this patent application are entitled as " INLINE SOLID STATE POLYMERIZATION OF PETFLAKES FOR MANUFACTURING PLASTIC STRAP (being used to make the online solid-state polymerization of the PET fragment of plastic strapping tape) ".

Solid-state polymerization (SSP) method of relate generally to polyethylene terephthalate of the present invention (PET) material, and the material of producing in this way, more particularly, solid-state polymerization (SSP) method that relates to exhausted and unused polyethylene terephthalate (PET) material, a kind of method that is particularly suitable for making the high-performance strapping tape, and the high performance strapping tape of producing in this way.

Can obtain exhausted polyethylene terephthalate (PET) from the salvage material station now, they mainly are from the plastics Sofe drink bottle.But, limiting viscosity (IV) value that this material presents is lower and heterogeneous (being wide distribution), and this feature hindered this PET material to be directly used in production in fact to need product than higher single limiting viscosity (IV) value, as high performance plastic strapping tape.At above-mentioned U.S. Patent application the 08/794th, one of discovery of the invention that is disclosed in No. 538 is that this inhomogeneity distribution of broad (promptly than) of PET properties of materials viscosity (IV) value does not in fact have a negative impact to the production of this high-performance strapping tape, and the present invention further is defined in the raw-material limiting viscosity of PET (IV) parameter of using when this PET materials processing become the high performance plastics strapping tape (value).

According to existing treatment technology, PET material (being exhausted or unused) all is ground into fragment and fragment at first, then these fragments and fragment is extruded into particle.Because various Sofe drink bottles are to be made with the differing materials that presents different IV values by different companies, so the PET material through pulverizing has relatively lower IV value and distribution range compares broad.This IV value is usually in the 0.60-0.80g/dl scope.According to existing treatment technology, people further think: in order to make premium quality product (as high performance plastic strapping tape) with this exhausted PET material, this material must present (promptly reaching) than higher IV value and narrow IV value distribution range after solid-state processing, need be with the fragment granulation as initial step before the beginning solid-state polymerization so should handle.Then, when PET particle experience solid-state polymerization (SSP), will raise its IV value and presenting than higher IV value and narrow IV value scope of these particles is then with this particle manufacture premium quality product that is enhanced, as the high-performance strapping tape.

As mentioned above, according to existing treatment technology, the PET material solid-state polymerization (SSP) of prior art is that the particle from the geometrical shape unanimity begins.But, in order to produce required strapping tape, the granular solid polymerization (SSP) of prior art needs considerable time, and (promptly about 12 to 19 hours) just can finish, and the heterogeneous mixture of not recognizing sheet and block PET material before the invention that disclosed for the 08/794th, No. 538 at U.S. Patent application of people needn't just can be reached the identical or higher average IV value of average IV value with direct the reaching with the prior art granulation by solid-state polymerization of faster mode (promptly approximately only need particulate material solid-state polymerization required time 1/4) through initial granulation.

More particularly, it is believed that: according to the instruction of prior art, the IV value distribute wide fragment directly solid state and at first granulation just can reach the state of " being fit to " production high-performance strapping tape.In this environment, term " is fit to " mean that this material not only presents than higher average IV value, and this material also presents narrow IV value scope.The particulate solid-state polymerization tends to cause, and in fact also causes material to present narrow IV value scope really, and this scope is regarded by those skilled in the art as the making premium quality product is requisite.But the final strapping tape that obtains of prior art presents the average IV value that is no more than 0.90g/dl.Opposite with above-mentioned prior art, it is found that the high-performance strapping tape of making according to the treatment technology that discloses presents the average IV value that is higher than 0.90g/dl in No. the 08/794th, 538, above-mentioned U.S. Patent application.So, might be according to the instruction of the invention that in No. the 08/794th, 538, above-mentioned U.S. Patent application, embodies in the mode of economy and as directly utilizing IV value to distribute than the PET material of the broad high performance plastic strapping tape of manufacturing in enormous quantities from the result who is pressed into flaky material experience solid-state polymerization without initial granulation.

Prior art is also by with United States Patent (USP) the 3rd, 767, and the solid-state polymerization of the sort of type that is disclosed for 601 (Knox) numbers is handled and illustrated that wherein the solid-state polymerization of useless PET does not need initial granulation step.But, the same with the above-mentioned type prior art, the useless PET film that the method that is disclosed as starting material and Knox patent is used in combination is to collect from the production line of making the PET film, it is characterized in that limiting viscosity (IV) is lower and distribution range is very narrow, for example 0.50-0.55g/dl.But, opposite with the instruction of Knox patent, in accordance with the teachings of the present invention, starting material have much wide inherent viscosity and distribute or plastisied dispersion, for example in the 0.6-0.8g/dl scope, and resemble the 0.90g/dl high, perhaps more particularly, the difference of limiting viscosity (IV) value is (or greater than) 0.05g/dl at least between different starting material or dissimilar starting material, may be 0.1g/dl at least, and the disparity range of raw-material limiting viscosity (IV) value can be 0.10-0.30g/dl.

Therefore, a target of the present invention is to seek a kind of universal method that can reuse the PET of exhausted and other form, so the invention provides a kind of improved online solid-state polymerization (SSP) novel method, this method will improve the IV value of this PET material, so that the PET fragment can be utilized, be processed to high performance plastic strapping tape subsequently.

Another target of the present invention provides and a kind of the PET fragment is processed into improved solid-state polymerization (SSP) novel method of high-performance strapping tape, makes the solid-state polymerization of fragment handle fast than existing agglomeration technique whereby.

The 3rd target of the present invention provides a kind of improved solid-state polymerization (SSP) novel method that the PET fragment is processed into the high-performance strapping tape, for example, this method can make full use of exhausted PET Sofe drink bottle, comprise thicker or blocky bottleneck portion, because these bottleneck portion are rolled into relatively thinner sheet, thereby improved the geometrical shape of this part effectively, so that experience more effective solid-state polymerization.

The above-mentioned target with other is to realize like this, i.e. foundation instruction of the present invention makes the material of final acquisition use in making required product (as the high-performance strapping tape) by providing a kind of limiting viscosity (IV) mean value that directly exhausted PET chip material is transformed into than higher material whereby.The high-performance strapping tape presents the enhanced welding strength.Tie up this fact of weak link in the product often in view of welding strength, welding strength is vital.With regard to high-performance strapping tape routine or prior art, welding strength equals 50% of strapping tape tensile strength and is considered to normal.But, the result that the present invention handles as foundation, the ratio percentage ratio of the tensile strength of the strapping tape of being produced and welding strength is compared with high-performance strapping tape routine or prior art can improve about 30%.Usually, when tensile strength increased, welding strength per-cent descended, and still, method of the present invention not only keeps welding strength, and has in fact improved welding strength per-cent.Not only production welding strength of method of the present invention is at least 50% strapping tape, and can the production welding strength up to 80% strapping tape.These are tied up product feature and help to clarify technically " high-performance " and be lashed to end how it feels.

According to method of the present invention, this innovative approach is to begin from obtaining the exhausted that comprises PET and unused material.These materials can obtain from the place of reclaiming strapping tape or material, and the initial IV value that these materials have than broad distributes or plastisied dispersion, for example between 0.60g/dl to 0.80g/dl, and resemble the 0.90g/dl high, more particularly, the difference of limiting viscosity (IV) value is (or greater than) 0.05g/dl at least between different starting material or dissimilar starting material, may be 0.1g/dl at least, and may be in the 0.10-0.30g/dl scope.This PET material comprises various impurity usually, as PVC.

Then, PVC and PET material are ground into the mixture of uneven fragment and fragment, and these PET and PVC fragment and fragment are placed baking oven or preheater, approximately 270-350 °F the about 3.5-4 of following preheating hour.As the result of this thermal pretreatment step, the PET material is dried, and has therefrom removed molecular water, and that PVC fragment and fragment become is brown.With PET with brown PVC material takes out from baking oven or preheater and allow them pass through a pair of smoother roller, this is inoperative but fragment is pressed into the fragment state to fragment usually to smoother roller.By camera system or equipment the brown PVC fragment or the fragment of shred are removed the color sensitivity.Subsequently, prepare to allow the PET fragment of having removed the PVC fragment enter fs of solid-state polymerization, be about to that this PET fragment is put into hopper and in anaerobic with have under the condition of nitrogen and heat, till they reach temperature between 420 to 430.

With about 1 hour or more times experience solid-state polymerization after the fs, these fragments are prepared the subordinate phase that enters solid-state polymerization, are about to take out, put into the storage cabin that does not have oxygen to exist and the nitrogen existence is arranged through the PET fragment of heating from hopper.These fragments are heated to about 425 °F and kept about 4 hours in this storage cabin.

In case described fragment is finished first and second stages of solid-state polymerization, the IV value of the PET material that is obtained just has been increased at least more than the 0.90g/dl, even up to 1.50g/dl, average IV value is approximately 0.95g/dl.Then, the PET fragment that allows the IV value be enhanced is finished extrusion molding by suitable extruding machine, so that produce high performance strapping tape.So, strapping tape by method production of the present invention, promptly utilize the strapping tape of the directly PET fragment production of experience solid-state polymerization can comprise the high-performance strapping tape that presents good tensile strength, welding strength and strength of joint feature, wherein used PET fragment needn't experience the granulation pilot process again and just reach average IV value and the distribution of the IV value in 0.90g/dl to 1.50g/dl scope that is approximately 0.95g/dl.In addition, the needed time of solid-state polymerization only is the part that prior art is handled PET material granule required time.Because the present invention helps shortening the treatment time greatly, during SSP handles, longer residence time can be arranged, so can produce IV value and the higher material of characteristic performance (being tensile strength and welding strength) economically.

Can more fully understand various other target of the present invention, feature and advantage from following detailed introduction in conjunction with the accompanying drawings, identical in the accompanying drawings reference symbol is represented identical promptly corresponding component all the time.Wherein:

Figure 1A-1C is the schema of explanation each step of PET fragment processing method of the present invention;

Fig. 2 is the schema of the nitrogen circulation part in solid-state polymerization stage of the present invention, comprises being used to remove the guard bed of HCl; And

Fig. 3 illustrates the relation between the various materials that obtained under the content of PET material in the starting material and limiting viscosity (IV) and the different condition.

Referring now to accompanying drawing 1A, exhausted is to collect from one or more different sources (comprising the salvage material place) with unused polyethylene terephthalate (PET) material, and these materials form uneven mixture through blend.Except containing or comprising polyethylene terephthalate (PET); this mixture also comprises various other materials (being impurity) usually; as PVC, polypropylene, polyethylene, paper etc.,, during the solid-state polymerization of PET material, do not wish to have these materials to exist according to the present invention.Therefore, be main component, be that the uneven mixture of submember at first is ground into fragment and fragment with exhausted PET material, so that these compositions or component are fit to represent the treatment step of feature of the present invention to be further processed according to the next one with exhausted PVC material and other impurity.These fragments and fragment derive from the bottle wall and the bottleneck of the Plastic Bottle of (for example) soft drink respectively, and wherein bottleneck portion (being fragment) is more abundant than bottle wall part (being fragment).Then, allow these material experience flotation separation handle, the effect of this processing is by tap density polyethylene, polypropylene and any paper material and PET material to be separated, and polyethylene, polypropylene and paper material composition float over the top of flotation unit and the PET material sinks to the bottom of flotation unit whereby.

The PET material that carried out preliminary treatment according to above-mentioned treatment step has quite wide limiting viscosity (IV) value scope, in fact this scope extends to than higher IV value (approximately 0.80g/dl) from lower IV value (approximately 0.60g/dl), average initial IV value is approximately 0.70g/dl, shown in curve A among Fig. 3.One of reason that forms this IV value distribution range than broad is that the Plastic Bottle of soft drink is to be made with different materials by different beverage bottle manufacturerss.The original mixture that also should further understand PET may have the IV value that is different from above-mentioned numerical value according to the concrete source of this material.For example, might use Recycled materials rather than use with the relatively low plastic bottles of soft drink beverages of IV value as feature, in other words, use the high-performance strapping tape that reclaims, these strapping tapes both can be made by existing treatment technology, also can be by treatment technology manufacturing of the present invention and the sort of strapping tape that can present 0.90g/dl or higher IV value.Under any circumstance, people all will realize original material may be and normally very different and comprise limiting viscosity (IV) value differ at least each other 0.05g/dl and may differ at least each other 0.10-0.30g/dl (in other words difference each other between 0.10 and 0.30g/dl between) material.People should further understand according to various instructions of the present invention by the IV value distribute than the uneven mixture production of broad (for example 0.60-0.80g/dl, and up to 0.90) and average IV value lower (for example 0.70g/dl) with the IV value distribution of curve B explanation shown in Figure 3 than broad (for example 0.70-1.50g/dl) and on average the IV value be possible than the material of higher (for example 0.95g/dl).

Certainly, the result or the feature of accurate curve and material will depend on the material characteristics of initial input and concrete processing parameter, therefore, curve C among Fig. 3 illustrates two kinds of final materials that the distribution of IV value is relatively broader and have different average IV values, the different material that promptly adopts different residence times to produce with D.So, be to be understood that, in fact only just can make the final material of handling through solid-state polymerization (SSP) by reducing the residence time of material in treating processes according to representative treatment technology of the present invention and parameter, this material has average IV value (for example about 0.80-0.85g/dl) and is fit to make the high-performance strapping tape that presents current acceptable routinely quality and performance characteristic.Therefore, when with regard to concrete application, in fact not needing the strapping tape (can also make the strapping tape that average IV value reaches 1.15g/dl) of very-high performance, can make the strapping tape of the high-performance, high-tensile and the welding strength that present acceptable routinely average IV value according to the various treatment technologies of representing feature of the present invention rapider, more economically.

Continuation is with reference to Figure 1A, after polyethylene, polypropylene and paper material or impurity have been separated from load material or each batch materials, PET and PVC fragment material placed suitable preheating can or baking oven, so that the experience pre-heating stage.In preheating can or baking oven, PET and PVC material are heated to about 270-352 temperature levels and continue about 3.5 to 4.0 hours time cycle.The purpose of pre-heating stage is that dry fragment material is therefrom removed molecular water and PVC is become brown basically.To from preheating can or baking oven, take out through the material (comprising brown PVC material) of preheating and carry towards a pair of smoother roller.

This allows bottle wall fragment uninterruptedly by roll gap to smoother roller, but the bottleneck fragment is driven plain.Bottleneck fragment by will be thicker flattens the geometrical shape that changes this part fragment, so that the bottleneck fragment that flattens is similar with bottle wall fragment.When these bottleneck fragments that promptly flatten through roll-in are heated to about 420-430 solid state temperature (solid stating temperature) subsequently, it is found that these fragments tend to recover their own original shape or configurations, but, owing to handle these materials in accordance with the teachings of the present invention, when these materials are heated to 420 °F-430 °F during its solid state, when they tended to recover their own original shapes or configuration, they did and form many crackles and crack like this in these material pieces.The distance of the interior any point of piece to its surface region reduced in these crackles and crack, so these are similar to script bottle wall fragment in the form of sheets in essence through the solid state that be shaped again formation crackle or fissured script are blocky bottleneck fragment.

After flattening, along travelling belt carry the fragment of fragment and pressing and use to the extremely sensitive pick up camera research of color they.These pick up cameras can be differentiated brown PVC fragment.Then, discern these brown PVC fragment the position and start gas blower or the equipment PVC fragment that these are brown that other is suitable is discharged into the discharging cabin from travelling belt.At this point for the treatment of processes, material has been removed useless PVC fragment and has been obtained purifying, only is made up of the PET fragment basically.Weigh for these brown PVC fragments, determine relation then with the PET fragment weight of passing through preheating, and with compare by the PET of preheater and the original gross weight of PVC chip samples, determine that whereby whether all PVC fragments all further remove that batch PET fragment material of processing according to solid state technology of the present invention from preparing.

Importantly from the material that pending solid state is handled, remove the PVC fragment, to prevent to produce the hydrochloric acid (HCl) that damages solid-state polymerization treatment facility or device tendency.In addition, if there is PVC to exist in the material of experience solid-state polymerization, brown striped will appear on cast film or the extruded material, will appear in the strapping tape of being produced subsequently.In addition, have the PVC material to have the melt filtration part that also will cause stopping up extruding machine, and PVC also have the tendency of limiting viscosity (IV) value of the fragment that reduces the experience solid-state polymerization.

Now, the PET fragment has been ready to enter the fs that solid-state polymerization is handled.As everyone knows, the different thickness feature of variant production or material or size make the material solid state to the predetermined needed time of IV value influence, and it is slow just as the relatively thinner bottle wall fragment part of the solid state of mentioned in above-mentioned relevant original patent application, thicker bottleneck fragment part.The fs of solid-state polymerization comprises improves the PET material temperature, and in view of fragment part or lumpy material in advance by flattening or roller process is transformed into fragment part or fragment material effectively, so can the enough relatively shorter time handle these bottles wall material or fragment material, thereby the raising processing efficiency comprises and handles mobile fragment material or bottle wall material.More particularly, the PET solid accumulation is in hopper, and this hopper provides one nitrogen turbulent oxygen-free environment is arranged.Material temperature is elevated to about 420 °F-430 °F.Fragment is piled up in hopper continuously and is moved to the bottom of hopper from the top of hopper continuously, and the IV value of this material slightly increases during this period.According to one embodiment of the invention or embodiment, the fs of solid-state polymerization approximately needs 1 hour.

Now, the subordinate phase that has been ready to enter solid-state polymerization through the PET material that heats.Therefore, these fragments are taken out from preheating hopper and be stacked into continuously in the storage cabin.In this storage cabin, keep about 4 hours processing time period through the PET fragment of preheating, during this period fragment from the top in this storage cabin to the bottom advance and this storage cabin in temperature levels according to nitrogen circulation in 380 to 425 scopes (below will more fully explain).Because such processing, the limiting viscosity of PET fragment (IV) value is (at first in about 0.60g/dl to 0.80g/dl scope, but may be up to 0.90g/dl) the wide distribution that will be increased to the average IV value of about 0.95g/dl significantly and have an IV value is (for example, shown in the curve B among Fig. 3, be distributed in the scope of about 0.70g/dl to 1.5g/dl), then, the fragment of high inherent viscosity can be taken out from this storage cabin, directly deliver to extruding machine, make the high-performance strapping tape that the IV value is at least 0.90g/dl by this extruding machine.

In the solid-state polymerization process, form various volatile organic compoundss.For example, ethylene glycol is to be the by product that decomposes of ethylene glycol and hydrochloric acid (HCl) is because polyvinyl chloride (PVC) is subjected to thermogenetic by by product, acetaldehyde that polyester produces.Subordinate phase employing nitrogen circulation at solid-state polymerization is in order to clear up this system, promptly to handle these pollutents.Can illustrate more comprehensively that with Fig. 2 nitrogen circulation is included in this storage bilge portion and purified nitrogen is provided and aspirates pollutent from the top in this storage cabin.Nitrogen upwards flows through this storage cabin and fragment, and nitrogen reduces this intrasystem dividing potential drop and allows the pollutent evaporation in doing so, makes acetaldehyde, ethylene glycol and hydrochloric acid (HCl) separate out and enter nitrogen gas stream effectively whereby.Nitrogen that provide in nitrogen circulation or that use both can be that the pure nitrogen that provides continuously also can be the nitrogen that derives from this circulation and removed pollutent.If select the latter, can reuse nitrogen certainly, this will provide a kind of more economical method.

Can be according to several different technology or the pollutent in the method removing nitrogen.One of them is by the formal siccative method that proposes of BEPEX .Another kind method is to remove the depleted product by the oxygen catalysis method of BUHLER  development.The method of further removing hydrochloric acid (HCl) from nitrogen circulation is that this device will be eliminated the HCl in the air-flow by use lime bag filtration unit.The another kind of method of removing HCl in nitrogen circulation is that guiding gas passes through water smoke, absorbs HCl whereby.Further effort can comprise that the use alkaline matter is guard bed, below it will be discussed more fully.

Because several reasons, clear the pollution off (particularly removing HCl) is particularly important.The amount of the HCl that emits in the subordinate phase of solid-state polymerization is fewer, however, the problem that the existence of HCl also bring at least two aspects may for apparatus and method of the present invention, i.e. the problem of catalytic activity aspect and etching problem are particularly when having or having liquid water and existing.Although be not to understand the degree that makes the platinum catalyst deactivation at the HCl that implements to be run into during the method for the present invention definitely,, this desactivation is well-known.Elevated temperature may remedy the desactivation of some catalyzer, but this will be a cost with the risk that increases sintering (being permanent deactivation).The size that increases catalytic bed also is a kind of selection that remedies lower catalyst activity, and still, this selection will increase the catalyzer cost, reduces intrasystem pressure and need bigger blowability.Relevant with etching problem is that liquid water tends to absorb the HCl by in the air-flow, and HCl is concentrated to the degree that corrosion speed becomes problem.This situation seemingly occurs on water cooler of giving birth to production fluid flow between cooling and the position between the absorbent bed.

Contemplated in accordance with the teachings of the present invention various embodiments, just as in Fig. 2, more specifically show and the front is introduced briefly like that since catalyzer deactivation that the HCl reaction causes and etching problem can by utilize the guard bed removing as soon as possible of alkaline matter in the method for the invention the HCl of appearance solve.This guard bed can adding in the BUHLER  line directly is connected on the front of catalyst bed, perhaps uses another kind of way, with the guard bed bag cabin filter assemblies of incorporating into, directly is connected on the back of solid state fluidizing bed.According to another embodiment, guard bedly can place bag back of cabin filter assemblies, to avoid particle plugging by PET.According to another embodiment, catalyst bed is omitted in smaller BEPEX  design, therefore, and in the guard bed back or bag cabin filter assemblies that directly is arranged in the solid state fluidizing bed.According to be arranged in bag cabin filter assemblies in the guard bed technology that is used in combination, a bag cabin strainer can use alkali solid (as calcium oxide, lime, caustic soda or supercarbonate) to apply, so that neutralizing acid.In this case, Chang Gui filter bag will replace with filter bag of the present invention.Moreover, the guard bed spray booth form that can also adopt spray water or supercarbonate.

Continuation can also be incorporated suitable watch-dog into production line (being system) with reference to Fig. 2, to detect the HCl content that exists in each processing element of this system or this system.Sometimes, owing to there is the PVC material to exist, the HCl content in the solid state fluidizing bed may rise.Simple HCl monitoring can comprise allows small volume of fluid flow into the washing bottle that is installed on the automatic titration unit with known flow velocity, and determine in order to keep the amount of constant alkali that consumes of pH value or alkaline matter, a kind of method of simple and direct measurement HCl content is provided whereby.

Because liquid water and HCl or Cl ₂The steel even the stainless steel capital may be corroded with surprising rapidity when existing simultaneously, constitute so device of the present invention can be selected promising structured material (as CPPC, PP or the steel of corrosion-resistant finishes are arranged) else.It also is known that the 13x molecular sieve that is used for BEPEX  drying treatment when having acid to exist will be degraded.Therefore, may have to use bigger bed for the drying power of recovering damage.Molecular sieve is rotten also may to produce powder.If this thing happens, these powder may be brought into the PET production material and/or be deposited in the lower end of drying receptacle and therefore hinder gas flow.In order to prevent this situation, appropriate filters can be provided on production unit, the powder mass that is produced is filtered and prevents whereby the pollution of powder mass, and the gangway that is easy to come in and go out can be provided in the bottom of equipment, so that clear up this equipment PET.According to another embodiment, can pour into nitrogen, when passing through fluidized-bed, it produces bypass siccative flue dust.Under any circumstance, make nitrogen obtain purifying in case clear the pollution off by one of aforesaid method, purified nitrogen just can be sent back to by pipeline, and portion sends into from the storage bilge, so that experience another nitrogen circulation.

Method of the present invention can batch-type or continous way enforcement.One of important factor relevant with method of the present invention is to remove volatile polymeric reaction product that may cause undesirable secondary reaction with nitrogen, comprises ethylene glycol and other impurity.For example, if also comprise 20ppm PVC in fragment after pre-heating stage, this fragment will produce HCl and make the siccative degraded that is used for purification nitrogen in the subordinate phase that solid-state polymerization (SSP) is handled so.Thereby because the reaction between HCl and the siccative, siccative is had to more than the annual replacing once.

Just as the front introduce briefly like that, fragment respectively first and second stages that solid-state polymerization is handled by hopper and storage cabin after, the fragment product is taken out and directly sends into scorching hot state the feed hopper of the extruding machine of production high-performance strapping tape from solid-state polymerization is handled the storage cabin of subordinate phase.With scorching hot fragment product is that directly deliver to the extruding machine of producing strapping tape from the storage cabin of solid-state polymerization subordinate phase be superior to material economically, because handle so a large amount of heats are stored in the polymer masses, have therefore reduced every pound of polymkeric substance desired power of extrusion molding.

In view of the diversity and the wide region of raw material characteristics viscosity (IV) value, the product degree of uniformity that derives from method of the present invention is astonishing.In addition, the heating and the solid-state polymerization of PET fragment carry out rapidly and easily, and are not adopting those problems such as polymer lumps, polymkeric substance adhesion treatment facility or polymer degradation that often occur under the particulate situation.The unpredictable consequence that realizes by method of the present invention is to utilize the lower average IV value of material production of various initial IV value to compare high product.In other words, be to handle at the experience solid-state polymerization to be used for making the starting material of strapping tape or in last strapping tape itself, not need the narrow IV value of initial value scope in fact in order to obtain high-quality high performance plastic strapping tape.

Therefore; what can understand is; solid-state polymerization of the present invention is handled and is advantageously caused with in Flow of Goods and Materials with produce the mode that all meets economic requirement aspect stop time and produce high performance strapping tape, yet the obvious the present invention of the above-mentioned instruction of foundation may also have many improvement projects and modification.For example, in order to reach required limiting viscosity (IV) value, can a little change accurate operating parameters and the program parameter that uses in the method for the invention.Limiting viscosity increase along with nitrogen amount and increase, along with solid-state polymerization in the stage increasing of temperature levels and increase, along with increasing in the prolongation of the residence time of solid-state polymerization in the stage.Determined already that the level that fragment is preheating to temperature of reaction will reduce the necessary storage of effective solid-state polymerization cabin size.In addition; further determined already; relatively Bao fragment presents the IV value of increase quickly than particle or thicker fragment; and obtain high IV value; and the most important thing is in view of fragment be can not become heavy-gravity in the fs of solid-state polymerization or in subordinate phase or cause the caking this fact, fragment (being different from particle or fragment) is the most satisfactory.Because oxygen will make polymer degradation and painted, so be not add oxygen at pre-heating stage or in the solid-state polymerization stage, and nitrogen is the preferred gas that uses in solid-state polymerization is handled, because it does not cause the caused side effect of oxygen, also because its both economical and easy utilization.So, should be appreciated that in the scope of claims the present invention can realize in the mode that is different from the introduction of this specification sheets.

Claims (18)

1. method of making pet material, this method comprises the steps:

Collect various pet materials, these materials have broad inherent viscosity and distribute, mainly be distributed in 0.60 to the 0.80g/dl scope, and can be up to 0.90g/dl, and the difference of the described inherent viscosity of the described pet material of collecting be 0.05g/dl at least;

With described pet material blend of collecting, and make described pet material form the heterogeneous pet material mixture that comprises a large amount of uneven sheets and block fragment in essence of limiting viscosity again through blend; And

Directly allow the heterogeneous PET material blends experience of described IV solid-state polymerization so that form the uneven PET material that a kind of limiting viscosity mean value is at least 0.85g/dl.

2. according to the process of claim 1 wherein that the difference of described inherent viscosity of the described pet material of collecting is 0.10g/dl at least.

3. according to the process of claim 1 wherein that formed uneven pet material has the average characteristics viscosity number that is at least 0.9g/dl.

4. according to the process of claim 1 wherein that the inherent viscosity of formed uneven pet material is in the scope of 0.9g/dl to 1.5g/dl.

5. according to the method for claim 1, further comprise the steps:

Make sheet and block fragment form the heterogeneous mixture of described limiting viscosity once more by described block fragment being refined into sheet shaped piece through blend.

6. according to the method for claim 5, the step that wherein forms the described heterogeneous mixture of limiting viscosity through blend once more comprises:

The heterogeneous mixture of described limiting viscosity that roll-in is made up of sheet and block fragment is so that be pressed into sheet shaped piece with described block fragment.

7. according to the method for claim 1, further comprise the steps:

To and form any PVC particle recognition of finding in the heterogeneous mixture of described limiting viscosity of the pet material that forms in the step once more in described collection, blend and come out, and before described solid-state polymerization, the described PVC clearance of particles that identifies be fallen.

8. according to the method for claim 7, wherein discern and remove described PVC particulate step and comprise the steps:

With the described heterogeneous mixture heating up of limiting viscosity that forms once more to making described PVC particle become brown temperature; And

The full scale clearance from the described heterogeneous mixture of limiting viscosity that forms once more of all described brown particles is fallen.

9. according to the process of claim 1 wherein that described solid-state polymerization step comprises the steps:

Nitrogen circulation is merged within the described solid-state polymerization; And

The HCl pollutant removal that will form in the described nitrogen circulation stage of described solid-state polymerization step is gone out, and its method is to make nitrogen and comprise that described HCl pollutent passes through the guard bed of alkaline matter during described nitrogen circulation.

10. a making is suitable for making the method for the pet material of high performance plastic strapping tape, and this method comprises the steps:

Collect various pet materials, these materials have broad inherent viscosity and distribute, mainly be distributed in 0.60 to the 0.80g/dl scope, and can be up to 0.90g/dl, and the difference of the described inherent viscosity of the described pet material of collecting be 0.05g/dl at least;

With described pet material blend of collecting, and making the heterogeneous mixture of limiting viscosity that forms pet material through the described pet material of blend again, this mixture comprises a large amount of uneven sheets and blocky fragment; And

Directly allow the heterogeneous mixture of described limiting viscosity of PET material experience solid-state polymerization so that form the uneven PET material that a kind of inherent viscosity is at least 0.85g/dl.

11. according to the method for claim 10, the described difference of the described IV value of the wherein said PET material of collecting is 0.10g/dl at least.

12. according to the method for claim 10, wherein formed uneven PET material has the average IV value that is at least 0.9g/dl.

13. according to the method for claim 10, limiting viscosity (IV) value that wherein formed uneven PET material is had is in the scope of 0.9g/dl to 1.5g/dl.

14. the method according to claim 10 further comprises the steps:

Make sheet and block fragment form the heterogeneous mixture of described IV once more by described block fragment being refined into sheet shaped piece through blend.

15., wherein form described step once more and comprise through the heterogeneous mixture of the IV of blend according to the method for claim 14:

The heterogeneous mixture of IV of described sheet of roll-in and block fragment is so that be pressed into sheet shaped piece with described block fragment.

16. the method according to claim 10 further comprises the steps:

To and form any PVC particle recognition of finding in the heterogeneous mixture of described IV of the PET material that forms in the step once more in described collection, blend and come out, and before described solid-state polymerization, the described PVC clearance of particles that identifies be fallen.

17., wherein discern and remove described PVC particulate step and comprise the steps: according to the method for claim 16

With the described heterogeneous mixture heating up of IV that forms once more to making described PVC particle become brown temperature; And

The full scale clearance from the described heterogeneous mixture of IV through forming once more of all described brown particles is fallen.

18. according to the method for claim 10, wherein said solid-state polymerization step comprises the steps:

Nitrogen circulation is merged within the described solid-state polymerization; And

The HCl pollutant removal that will form in the described nitrogen circulation stage of described solid-state polymerization step is gone out, and its method is to make nitrogen and comprise that described HCl pollutent passes through the guard bed of alkaline matter during described nitrogen circulation.

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