US3425969A

US3425969A - Process of preferentially modifying stereoregular polyhydrocarbons to improve dyeability

Info

Publication number: US3425969A
Application number: US502719A
Authority: US
Inventors: Jack J Press
Original assignee: Individual
Current assignee: Individual
Priority date: 1961-04-04
Filing date: 1965-10-22
Publication date: 1969-02-04
Anticipated expiration: 1986-02-04

Description

United States Patent 20 Claims ABSTRACT OF THE DISCLOSURE A process of increasing the aflinity of a stereoregular polyhydrocarbon for dyes whereby a modifier is dispersed in the polyhydrocarbon predominantly in the amorphous regions.

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

This application is a joint continuation-in-part of my copending applications Ser. No. 400,611, filed Sept. 30, 1964, now Patent No. 3,366,710, Jan. 30, 1968; Ser. No. 400,612, filed Sept. 30, 1964, abandoned; Ser. No. 406,- 631, filed Oct. 26, 1964, now Patent No. 3,337,652, Aug. 22, 1967; Ser. No. 406,439, filed Oct. 27, 1964, now Patent No. 3,375,213, Mar. 26, 1968; Ser. No. 414,919, filed Nov. 30, 1964, now Patent No. 3,316,328, Apr. 25, 1967; Ser. No. 427,518, filed Jan. 22, 1965, abandoned; Ser. No. 433,226, Feb. 16, 1965; Ser. No. 491,055, Sept. 28, 1965, now Patent No. 3,337,651, Aug. 22, 1967.

It is generally recognized that dyeing takes place almost entirely in the more open and more readily accessible non-crystalline or amorphous regions of a polymeric structure. When a modifier, which has been added to the polyhydrocarbon to increase its aflinity for dyes, is entrapped in the crystalline portions of the molecule, it is not readily available for improvement in dyeability.

It is known that, in general, stereoregular polyhydrocarbons have a hydrophobic nature and it is difficult to disperse a hydrophilic modifier therein to increase the aflinity of the polyhydrocarbon for dyes under normal processing conditions.

In the art, the conventional procedure for dispersing modifiers in the stereoregular polyhydrocarbon is to mix the modifier therein at a temperature of 50 C. to 150 C. above the melting point of the polyhydrocarbon. The polyhydrocarbon does not exist in the crystalline state at this temperature but rather is in a molten form. In this manner the modifier is dispersed throughout the mass. However, when the molten mass is solidified, a crystalline area does form containing a major portion of the entrapped modifier. As stated above, such entrapped portions of modifiers are unavailable for dyeing purposes. Also, the dispersion of the hydrophilic modifiers in the amorphous regions of the polyhydrocarbon is poor due to the hydrophobic nature of the polyhydrocarbon.

To overcome the above ditficulties inherent in the conventional procedure, it has been found necessary to utilize large portions of the modifier in order to entrap a satisfactory amount of the modifier in the amorphous regions of the polyhydrocarbon. It has also been found necessary to utilize high percentage of secondary dispersing aids for the modifier above in order-to obtain acceptable results in dyeing.

. tile processing or product. It has also been found that a long retention time is required in commercially available equipment during processing.

We have discovered a process wherein a hydrophilic modifier may be concentrated in the amorphous regions of the stereoregular polyhydrocarbon. This may be accomplished without the aid of secondary dispersing aids and with minor amounts of modifiers. It has been found that the dispersion of the modifier in the amorphous regions of the polyhydrocarbon is accomplished with greater uniformity and a higher degree of interaction between the dispersed modifier and the polyhydrocarbon.

It is therefore an object of this invention to provide a process of dispersing hydrophilic modifiers preferentially in the amorphous regions of a stereoregular polyhydrocarbon.

Another object is to provide a process of increasing the dye afiinity of stereoregular polyhydrocarbons with minimum amounts of hydrophilic modifiers.

A further object is to provide a process of low cost, which is adaptable for use under a wide variety of service conditions, whereby a hydrophilic modifier may be dispersed preferentially in a specified region of a hydrophobic stereoregular polyhydrocarbon with ease and efficiency.

Other objects and many of the attendant advantages of this invention will be better understood by reference to the following detailed description.

The process of this invention, which accomplishes the preferential dispersion of a hydrophilic modifier into the amorphous regions of a hydrophobic stereoregular polyhydrocarbon, in general, comprises the mixing of a discontinuous physical mixture of the polyhydrocarbon and modifier at a temperature between the first order transition temperature and the second order transition temperature of the stereoregular polyhydrocarbon at a pressure of to 20,000 pounds per square inch.

The first order transition temperature and the second order transition temperature are fully defined in Chapter 12 of Fibers From Synthetic Polymers, 1953, Elsevier Publishing Company and Chapter XXIII-3 in Man-Made Textile Encyclopedia, 1959, Interscience Publishers. In summary, the first order transition temperature is the crystalline melting point of the polyhydrocarbon and the second order transition temperature is the softening temperature of the non-crystalline portions of the polyhydrocarbon.

In theory, at low temperatures, i.e. below the first order transition temperature of the polyhydrocarbon, the melt viscosity of the polyhydrocarbon is very high permitting much higher shear stresses to be transmitted to the hydrophilic modifier. In addition, the mixing stresses are essentially localized in only the noncrystalline portion of the polyhydrocarbon thereby mixing the hydrophilic modifier therein.

The major problem with stereoregular polyhydrocarbon is to protect them against thermal and oxidative degradation during processing. If care is not taken, the polyhydrocarbon will rapidly decompose and degrade to a low molecular Weight unstable product which is unsuitable for use in making shaped products. This is essentially the effect when a processing temperature is utilized which is above the first order transition temperature of the polyhydrocarbon. Further, processing at such temperatures leads to the distribution of the modifier throughout the molten mass the major portion of which is crystalline in nature. Therefore a temperature should be used in processing which is below the first order transition temperature of the stereoregular polyhydrocarbon.

Also, when a temperature is used which is below the second order transition temperature, the non-crystalline or amorphous portion of the stereoregular polyhydrocarbon is in the brittle, non-plastic state and, as such, it will not mix and is otherwise unsuitable for processing. Therefore, the mixing stage should be above the second order transition temperature of the stereoregular polyhydrocarbon.

Further, the mixing stage should be carried out at a pressure between 100 and 20,000 pounds per square inch. If a pressure is used which is below 100 pounds per square inch, there will not be a sufficient increase in plasticity to permit acceptable mixing at temperatures below the first order transition temperature and an acceptable level of mixing is essential to uniform dispersion.

However, if the mixing stage of the process is in excess of 20,000 pounds per square inch, the result will be mechanical degradation of the stereoregular polyolefin due to increased shear. It also results in a reduction in production rate if not a shut down due to the inherent limitations of the commercially available equipment.

Prior to the mixing stage of my process, the stereoregular polyhydrocarbon and hydrophilic modifier may be prepared as a discontinuous physical mixture in any manner known in the art.

However, it has been found that for greater ease of processing, the discontinuous physical mixture of stereoregular polyhydrocarbon and hydrophyllic modifier should be heated to at least 50 below the first order transition temperature of the polyhydrocarbon prior to processing. The discontinuous mixture, which is not very plastic, is difficult to mix especially when there is very little pressure in the system. If the mixture is heated to the temperature presented above, it becomes somewhat plastic for greater ease of processing in the mixing stage of the present process. In this manner processing is more effective and less time is required which is an economic advantage in commercial systems.

It has also been found that if the discontinuous physical mixture is subjected to a pressure of 500 pounds per square inch, prior to the mixing stage of the present process, much of the entrapped air is removed from the mass and the mixture is more suitable for effective processing for it is more plastic and less time is required in processing to produce the results desired. If a pressure of 500 pounds per square inch is applied to the mass prior to processing, the pressure at the mixing stage should then be altered to between 500 and 10,000 pounds per square inch. At 100 pounds per square inch pressure there is marginal improvement in plasticity which is neces sary for effective and efficient mixing. If the pressure in the mixing stage of the process is increased to at least 500 pounds per square inch, sufficient improvement in plasticity is achieved to render the processing more effective. As a result, the modifier is more uniformly dispersed in the amorphous regions of the polyhydrocarbon and improvement in dyeability is achieved. Also, it is known that to process such a mixture with commercially available equipment at reasonable rates, the pressure should be below 10,000 pounds per square inch. However, with massive equipment and lower production rates, the pressure may be increased to 20,000 pounds per square inch.

After the hydrophilic modifier is dispersed in the amorphous region of the polyhydrocarbon in the mixing stage of the process, the mass may be formed by molding or die forming processes to the shape desired. This step is carried out at a temperature of about 50 to 150 C. above the first order transition temperature for ease of forming. In this manner the viscosity of the material is lowered and the mass is made more fluid. This stage of the process should not be carried out above the temperature prescribed because the material bing processed will degrade and discolor above this temperature and will be useless as a commercial product.

In theory, not all the crystalline matter goes into the molten state because of the limitation of time and temperature. In any case, it is believed that, due to the interaction of the modifier with the amorphous regions of the polyhydrocarbon, there is less tendency for the modifier to migrate to the crystalline portion even when the mass is rendered somewhat fluid. Even if the crystalline portion of the polyhydrocarbon is rendered completely molten, there appears a preference for the modifier to remain associated with the less stereoregular portion of the polyhydrocarbon which will again become the amorphous region when the material is solidified and crystallinity takes place.

After the material is formed, the shaped mass may be solidified simply by contact with air, water or metal. This step is usually carried out at atmospheric pressure but not necesarily at a temperature below the second order transition temperature of the polyhydrocarbon.

To better explain my novel process, a brief discussion of the effects of temperature and pressure on the plasticity and melt mixing characteristics of polymers, particularly as related to highly crystalline stereoregular polyhydrocarbons, will be helpful. Pertinent temperature limitations are best described in terms of the crystalline (first order transition) and non-crystalline or amorphous (second order transition) melting or freezing temperatures as determined under essentially normal ambient pressure.

As pressures are increased at temperatures below the crystalline melting point, imperfect and smaller crystals begin to be disrupted and flow and increase plasticity. At higher pressures with mechanical mixing and internal working this increased plasticity and effective softening can be accomplished at temperatures approaching the lower second order transition temperature. As an example, isotactic highly crystalline polypropylene has a first order transition temperature or melting point of about 170 C. at atmospheric pressure. Using the standard ASTM (Method D 64856) heat distortion or plasticity test, isotactic polypropylene under a 66 psi. load softens and deforms at C. and under a 264 p.s.i. load softens at the low temperature of only 60 C. The limiting second order (non-crystalline freezing or thawing) temperature, below which pressure fusion and melt mixing are impractical, is about -10 C. for isotactic polypropylene.

The above described effects of pressure on reducing the effective temperature at which the stereoregular polyhydrocarbon matrix in my differential mixing process will be sufficiently plastic to fuse and melt mix, also have a similar effect on reducing the effective melt mixing temperature of the various hydrophilic polymeric modifiers described in my copending applications. My hydrophilic polymeric modifiers are characterized by a higher dielectric constant and moisture regain than the polyhydrocarbon matrix, are soluble or dispersible in water or oxygenated organic solvents (alcohols, ketones, ethers, etc.), are not soluble in the polyhydrocarbon, and are fusible at a temperature not exceeding the normal processing temperatures to 350 C.) of the polyhydrocarbon. My water and oxygenated solvent compatible hydrophilic polymeric modifiers are not soluble in, but can be fused and melt dispersed in the hydrocarbon polymer. If the modifier is too soluble in the polyhydrocarbon it sweats out during processing, can be readily removed by water or solvent leaching and, in dyeing, gives excessive surface dyeing and dye crocking and interferes with dye penetration. In addition, a soluble modifier, when melt mixed with a stereoregular polyhydrocarbon and then solidified, remains in both crystallized and non-crystalline or amorphous regains, will interfere with proper crystallization, and adversely effect stiffness and temperature stability of fiber or film and will show negligible functional improve ment.

My selected hydrophilic modifiers are fusible and dispersible in the polyhydrocarbon but are not sufiiciently compatible to be a part of the more uniform and dense crystalline areas when they form during solidification. It appears that my modifiers not only concentrate in the amorphous areas during solidification but also form a continuous network throughout these areas and give maximum benefits in dyeability, particularly dye penetration.

I have now found, surprisingly, that further substantial improvements in functional modification with my selected modifiers can be achieved during initial modification of the polyhydrocarbon by melt mixing as described, the modifier preferentially with the more amorphous portions of the polyhydrocarbon while retaining the original better defined and larger crystallites in a non-melted form. This is accomplished by mixing the polyhydrocarbon and modifier under pressure at a temperature below the melting temperature of the more perfect crystallites but above the second order transition temperature (amorphous melting temperature) of the polyhydrocarbon.

This novel method of preferential melt modification of stereoregular polyhydrocarbons with my selected hydrophilic polymeric modifiers has a number of very desirable features. The modifieris initially concentrated in the amorphous regions where it is most desired in the final formed fiber or film. Well defined unmodified crystallites are retained and developed to act as effective nucleation centers for improved crystal development and structural stability in the formed product. The melt viscosity and effectiveness of mixing at the lower temperatures are much higher than at the normally used temperatures well above the crystalline melting point. Limiting the melt mixing to the amorphous polyhydrocarbon regions and the modifier reduces the proportion of total polymer being worked, with a reduction in power requirement and more intensive dispersive action on the modifier. Eifectiveness of dispersion and retention of crystallites can be further improved by minimizing external heating and relying on mechanical working under pressure to internally generate heat preferentially in the modifier and amorphous region. The need for the addition of expensive stabilizers to protect the polyhydrocarbon during high temperature processing is reduced. Color of the modified polymer and uniformity of processing into fiber, film, coating or other structure are greatly improved. The amount of modifier and the need for lower melting secondary modifiers to improve dispersibility and dyeability in synergistic combinations with primary modifiers are reduced. Numerous other advantages will be apparent to those experienced in the art.

The benefits of my novel process may be accomplished in a practical way by a combination of several process steps which may be carried out sequentially in continuous screw or impeller equipment or in batch mixers (Werner- Pfieiderer, Banbury, etc.) provided with suitable means for controlled heating, pressurizing, mixing, conveying and/or cooling, in direct combination or separately as required.

PROCESS As stated, I start with a discontinuous mechanical mixture of polyhydrocarbon and modifiers prepared by any of the methods known in the art. The mixture, essentially free of moisture or solvents, is fed into .a continuous screw or impeller extruder or a suitable batch mixer and subjected to heating at a temperature below the first order transition temperature or crystalline melting point and above the second order transition temperature or noncrystalline softening point of the polyhydrocarbons (as determined .at atmospheric pressure) at initial pressures of less than 100 p.s.i. and with sufficient intensity of mixing to compact the discontinuous mixture into a solid continuum, and a temperature below the normal melting temperature of the polyhydrocarbon.

In the mixing stage of the process, the solid mixture of polyhydrocarbon and modifier at a pressure in the 6 range of 100 to 20,000 p.s.i., preferably 500 to 10,000 p.s.i., is intensively mixed with little or no added heat until the modifier is uniformly dispersed preferentially in the amorphous portion of the polyhydrocarbon polymer and the modified polymer is conveyed to the next step.

As an optional step, the modified polyhydrocarbon may then be heated for a short time up to or above the normal melting temperature of the polyhydrocarbon, by continued mixing or by subsequent external heating at high or reduced pressure, in order to facilitate manipulation into fiber, film, rod and tubing.

In the last stage of the process the formed structure is solidified by contact with a solid, liquid or gas at a reduced pressure and temperature.

These steps may be carried out sequentially or intermittently with the addition of other steps as required.

As a preliminary step, I prefer to initiate my process by heating the polymer-modifier mixture to a temperature at least 25 C. and preferably at least 50 C. below the crystalline melting temperature of the stereoregular polyhydrocarbon. Conveniently, the polyhydrocarbon and modifier may be pre-mixed in powder form or the modifier in solution may be coated on the polyhydrocarbon, in powder or pellet form and then dried prior to the actual mixing stage of the process. The temperature should be sufficiently low to permit higher pressure melt mixing in the mixing stage without excessive temperature buildup.

The mixture may be slightly heated and/or cooled in the mixing stage to maintain the desired intermediate temperature for optimum uniform preferential mixing with good production rate. Heating and/or cooling may be accomplished by circulation of temperature controlled water, oil or other liquid through external jacket, extruder screw, impeller, mixing arm, etc.

In the forming stage, where a temperature above the crystalline melting point may be required, pressure, time and intensity of mixing should be minimized for maximum retention of crystallites. Crystallite retention, however, is not a requirement of my process as long as the initial modification was carried out under suitable conditions for my preferential melt mixing process. Under optimum conditions, in continuous processing, all process steps may be accomplished in two to fifteen minutes process or retention time. Similar batch processing using, for example, a combination of a Banbury mixer and a two roll sheeting mill may require from ten to thirty minutes. A minimum of about two minutes overall process time appears to be necessary to obtain uniform results. Processing requiring more than thirty minutes may result in excessive mechanical degradation, increased color and excessive equipment and power costs.

The following examples illustrate but are not intended to limit my novel method for preferential modification of stereoregular polyhydrocarbons.

Example 1 Ninety-five parts by weight of finely powdered (50 to 200 mesh) isotactic poly-4-methyl-1-pentene (M.P. about 235 C., isotacticity about was intimately tumble mixed with five parts by weight of finely powdered (50 to 200 mesh) poly-N-vinyl-methyloxazolidinone (M.P. about 250 0., molecular weight about 150,000).

The powder mixture was then fed into the hopper of a sturdy 2.5 inch diameter, 30:1 L/D ratio continuous screw compounding extruder having a conventional polyethylene type screw, five throttling type temperature controlled barrel zones, a back pressure regulating gate valve and a heated strand, die with eight /8 inch holes. The L/D ratio refers to the effective length to diameter ratio of the extruder screw in the barrel. The throttling or compensating type temperature controls supplement the heat generated by melt mixing with the minimum supplemental heating or cooling required to maintain the preset zone barrel temperature. A very sturdy extruder was used with a drive and gate valve capable of developing a 20,000 p.s.i. back pressure. The extruder was set up in such a way that the extruded strands were cooled in a water bath and then cut into small pellets as is normal in the art.

The extrusion mixing was performed under two sets of conditions. In the 1A or blank test, compounding was carried out under normal conditions with the barrel zone temperatures of 250-250-250-250275 C., a back pressure of 450 p.s.i., and a die temperature of 300 C. The extrudrer screw was driven at maximum speed and the polymer retention time was about 4 minutes. The strands were cooled, pelletized, dried, stored under dry conditions and labeled Test 1A.

Test 1B was run in similar fashion except that the barrel zone temperatures were set at 150l75175200-245 C., the gate valve was adjusted to give a back pressure of 20,000 p.s.i. and the die temperature was set to maintain a die temperature of 265 C. In the first or back zone the powder mixture was compacted to remove air and was preheated at a temperature well below the first order transition temperature of the stereoregular polyhydrocarbon, in zones two to four the mixture was intensively mixed while still at a temperature below the crystalline melting temperature to uniformly disperse the modifier polymer preferentially throughout the amorphous portion of the polyhydrocarbon while under a very high backpressure, in zone five the temperature was increased to slightly above the crystalline melting temperature, and, after passing the processability. Similar results were obtained using isotactic polystyrene instead of the poly-4-methyl-l-pentene.

Example 2 In accordance with the procedure of Example 1, I prepared and evaluated modifications of a representative stereoregular polypropylene (M.W. about 350,000, M.P. 170 C., melt index 3, and isotacticity of 95%) using normal (200200-200200250 C. zone temperatures, 400 p.s.i. backpressure and 250 C. die temperature) and my preferential (ll20135-150-170 C. zone temperatures, 8000 p.s.i. backpressure and 200 C. die temperature) compounding conditions.

The modifications A to H were made at the by weight level using high melting primary polymeric modifiers (4% by weight) in synergistic combination with lower melting polar compounds or selected secondary polymeric modifiers (1% by weight). Modifications A and B were made with primary modifier carboxymethyl cellulose (1.3 substitution, medium viscosity) and tertiary dihydrogenated tallow methyl amine, C and D were made with primary modifier sodium salt of sulfonated polyvinyltoluene (M.W. 400,000) and quaternary dihydrogenated tallow dimethyl amine chloride, E and F were made with primary modifier poly-N-vinyl-methyloxazolidinone and polyvinyl methyl ether (M.W. 10,000), G and H were made with primary modifier poly-N-vinyl pyrrolidone (M.W. 40,000) and a polycondensate of adipic acid and propylene glycol (M.W. 12,000).

Results of the dispersion uniformity tests were as follows:

Normal process. Preferential process Spin draw, r.p.m holes plugged, minutes Holes plugged, 4 hours None None None None gate valve, the polymer was further heated at a reduced pressure for a short time to facilitate proper strand and pellet formation. The total retention time was about 7 minutes and the modifier was preferentially mixed with the amorphous portion of the polyhydrocarbon under high pressure for more than 3 minutes. Similar tests were repeated using only 2% modifier with normal processing (1C) and my preferential processing (1D) conditions.

In order to compare the uniformity of dispersion of the modifier in the tests they were run individually through a normal single end multifilament extruder-gear pump-die combination and down through an air quench pipe to cool the extruded fibers. The fibers were extruded at 310 C. through a die with 30 holes having 0.025 inch diameters. Uniformity was compared two ways. First, the spin draw limit of the extruded multifilament yarn was determined by winding the yarn on variable speed take-up tube and gradually increasing the take-up speed (r.p.m.) until the filaments began to break. In the second uniformity test, multifilament extrusion continued for four hours or until at least 10% (3 holes) in the die became plugged. The following results were obtained:

Test 1A Test 10 Test 1B Test 1D Uniformity of dispersion of the modifiers was greatly improved using my preferential modification process.

Example 3 In accordance with the procedure of Example 1 and the processing temperatures of Example 2, I prepared and evaluated modified stereoregular polypropylene (film grade, melt index 15, M.P. 170 C., and isotacticity 99% The back pressure for the normal processing was 200 p.s.i. and for my preferential processing was 500 p.s.i. The polymer retention time in the preferential compounding was down to about 3 minutes overall and between 1 and 2 minutes under pressure at a temperature below the crystalline melting temperature.

The modifications were made with representative hydrophilic heterocyclic copolymers at 10 to 15% by Weight levels. Modifications A and B were made with a 50/ 50% by weight copolymer of N-vinyl-methyloxazolidinone and vinyl acetate at a 15% level, C and D were made with a /30 copolymer of N-vinyl pyrrolidone and ethyl acrylate at a 15 level, E and F were made with a partially substituted or grafted poly N-vinyl pyrrolidone having /20 N-vinyl pyrrolidone and N- Emir-211W 1i mir,r .r 4 5 000 2,000 2,800 65 vinyl lauryl-pyrrolidone at a 10% level, and G and H oespugge ,mms... 60 i f plugged Moms 1) 0) f made Wlth a 60/40 copolymer of N vinyl morpholme and methyl methacrylate at a 15% level. None. The evaluation results were as follows:

A B C D E F G H Normal process X Preferential process X n X X Spin draw, r.p.n1 10% holes plugged, minut Holes plugged 4 hours One The preferentially modified polyhydrocarbons in the X X X X 6 Two None Even at high levels of modification my preferential greatly improves uniformity of dispersion.

9 Example 4 In accordance with the compounding procedures of Example 1, I prepared modifications of a representative linear polyethylene (density 0.95, M.P. 135 C., molecular weight about 100,000) using normal (160-160-160- 170-180 zone temperatures, 250 p.s.i. back pressure, and 210 C. die temperature) and my preferential (80-100- 110-125-145 C. zone temperatures, 1000 p.s.i. back pressure, and 165 C. die temperature).

Modifications were made at the 10% by weight level using a 50/50% by weight copolymer of ethylene and maleic anhydride (A and B), polyvinyl methyl ether (C and D) and a 60/40% by weight copolymer of vinyl methyl ether and maleic anhydride.

To compare uniformity of dispersion, the modified polyethylene pellets were oven dried and then extruded under normal conditions into blown film using a one inch 12:1 L/D laboratory extruded and a crosshead die (tip 0.638" OD. and orifice 0.681" I.D.). The films, processed under similar conditions, were then compared subjectively for uniformity of appearance. The modifications prepared under normal compounding conditions did not blow up or draw uniformly and gave uneven, streaky films. Similar modifications prepared under my preferential processing conditions, blew up uniformly and gave even films with no streaks.

Example In accordance with the procedure of Example 1 and the processing temperatures of Example 2, I prepared and evaluated modified stereoregular polypropylene (film grade, melt index 15, M.P. 170 C. and isotacticity 99%). The back pressure for the normal processing was 200 psi and for my preferential processing was 500 psi. The polymer retention time in the preferential compounding was down to about 3 minutes overall and between 1 and 2 minutes under pressure at a temperature below the crystalline melting temperature.

The modifications A to H were made with representative primary hydrophilic copolymer modifiers with and without low percentages of synergistic secondary modifiers using normal and preferential processing conditions. Modifications A and B were made with a 50/ 50% by weight copolymer of N-vinyl methyloxazolidinone and vinyl acetate at a by weight level, modifications C and D were made with 9.9% of the previous copolymer together with 0.1% of a polycondensate of dimerized linoleic acid and triethylene tetramine (M.W. 6000, amine value of 90), modifications E and F were made with 10% by weight of a 70/ 30% by weight copolymer of N-vinylpyrrolidone and ethyl acrylate and modifications G and H were made with 9.8% of the previous copolymer together with 0.2% by weight of oleylamide.

The evaluation results were as follows;

l T.1. Transition temperature.

Without adversely affecting the crystalline melting point of stereoregular hydrocarbons, they can be copolymerized with minor percentages of other monomers to greatly reduce the second order transition temperature or brittle point and increase the temperature range effective under my novel preferential melt dispersing process. For fiber use it is preferred that the major monomer in the stereoregular polyhydrocarbon constitute at least 85% by weight of the polymer and that the melting temperature of the hydrocarbon polymer or copolymer be at least 150 C. For use in coating or adhesive bonding applications the comonomer may constitute up to 49% by weight of the polymer and the melting temperature may be as low as 100 C. The comonomer used may be one or more of the other monomers used in making the listed homopolymers or they may be any other substantially hydrocarbon monomer which does not significantly change the hydrophobic or the stereoregular character of the polymer. The comonomer may be present sequentially in the polymer in an individual comonomer or a prepolymer block form in relation to the principal hydrocarbon monomer in the polymer.

Obviously, many modifications and variations of the present invention will become apparent to one skilled in the art in view of the above teachings. For instance, functional improvements such as adhesion, printability, and static resistance are also strongly dependent on the pref erential modification of the amorphous regions. It is therefore to be understood that the invention as set forth in the appended claims may be practiced otherwise than as described.

I claim:

1. A process of dispersing dye affinity improving hydrophilic modifiers preferentially into the amorphous regions of a stereoregular polyhydrocarbon comprising:

providing a compacted discontinuous physical mixture of 80 to 99% of a stereoregular polyhydrocarbon and 1 to 20% of a hydrophilic modifier, and

mixing said discontinuous physical mixture into a continuous mass at a temperature between the 1st order transition temperature and the 2nd order transition temperature of said stereoregular polyhydrocarbon at a pressure of 100 to 20,000 pounds per square inch.

2. The process of claim 1 wherein the 1st order transition temperature lies in the range of 100 C. to 350 C. and the second order transition temperature lies in the range of 25 C. to 100 C.

3. The process of claim 1 wherein said stereoregular polyhydrocarbon is polyethylene and said mixing stage Normal process. Preferential process- Spin draw, rpm..- 10% holes plugged, minutes Holes plugged 4 hours One .iiii''. n One X X X X 00 1, 300 450 1, 800 400 1,400 550 2, 000 40 55 50 Even at high levels of modification my preferential process greatly improves uniformity of dispersion.

The following are included in the list of stereoregular polyhydrocarbons which may be processed to increase their affinity for dyes with their 1st order and 2nd order transition temperatures set forth.

5. The process of claim 1 wherein said stereoregular polyhydrocarbon is poly-4-methyl-1-pentene and said mixing stage is carried out at a temperature between C. and 235 C.

6. The process of claim 1 wherein said stereoregular polyhydrocarbon is polystyrene and said mixing stage is carried out at a temperature between 100 C. and 230 C.

7. The process of claim 1 wherein said stereoregular polyhydrocarbon is isotactic poly-l-butene and said mixing stage is carried out at a temperature between C. and 127 C.

8. The process of claim 1 wherein said stereoregular polyhydrocarbon is poly-3-methyl-l-butene and said mixing stage is carried out at a temperature between 50 C. and 310 C.

9. The process of claim 1 wherein the physical mixture of stereoregular polyhydrocarbon and hydrophilic modifier is heated to a temperature of at least 50 C. below the 1st order transition temperature prior to mixing.

10. The process of claim 9 wherein said heating is carried out at a pressure of less than 500 pounds per square inch and said mixing is carried out at a pressure of 500 to 10,000 pounds per square inch.

11. The process of claim 1 wherein subsequent to said mixing stage, said stereoregular polyhydrocarbon is heated to a temperature of at least the lst order transition temperature of said stereoregular polyhydrocarbon for ease of forming into a shaped article.

12. A process of dispersing dye afiinity improving hydrophilic modifiers preferentially into the amorphous regions of poly-4-methyl-1-pentene comprising:

providing a compacted discontinuous physical mixture of 80 to 99% of poly-4-methyl-l-pentene and 1 to 20% of a hydrophilic modifier, and heating said physical mixture to a temperature of less than about 185 C.

mixing said discontinuous physical mixture into a continuous mass at a temperature in the range of 175 C. to 200 C. at a pressure of 2000 pounds per square inch.

13. The process of claim 12 wherein said physical mixture is initially heated to a temperature of 150 C.

14. The process of claim 12 wherein subsequent to said mixing stage said mass is heated to a temperature of about 265 C.

15. A process of dispersing dye affinity improving hydrophilic modifiers preferentially into the amorphous regions of polypropylene comprising:

providing a compacted discontinuous physical mixture of to 99% of polypropylene and 1 to 20% of a hydrophilic modifier, and

mixing said discontinuous physical mixture into a continuous mass at a temperature in the range of to 170 C. at a pressure of 8000 pounds per square inch.

16. The process of claim 15 wherein said physical mixture is heated to a temperature of less than 120 C. prior to said mixing stage.

17. The process of claim 15 wherein subsequent to said mixing stage, said mass is heated to a temperature of about 200 C. and formed into a shaped article.

18. A process of dispersing dye affinity improving hydrophilic modifiers preferentially into the amorphous regions of polyethylene comprising:

providing a compacted discontinuous p'hysical mixture of 80 to 99% of polyethylene and 1 to 20% of a hydrophilic modifier, and

mixing said discontinuous physical mixture into a continuous mass at a temperature in the range of 100 C. to C. and a pressure of 1000 pounds per square inch.

19. The process of claim 18 wherein said discontinuous physical mixture is heated to a temperature of 80 C. prior to said mixing stage.

20. The process of claim 18 wherein subsequent to mixing, said mass is heated to C. prior to forming into a shaped article.

References Cited UNITED STATES PATENTS 3,069,220 12/ 1962 Dawson. 3,315,014 4/1967 Coover et al. 3,346,521 10/1967 Fairbairn et al. 3,315,014 4/ 1967 Coover et al. 3,346,521 10/1967 Fairbairn et al.

WILLIAM H. SHORT, Primary Examiner.

E. A. NIELSEN, Assistant Examiner.

US. Cl. X.R.