US3533731A - Dyeing of polyolefins - Google Patents

Description

United States Patent 01 ifice 3,533,731 Patented Oct. 13, 1970 3,533,731 DYEING F POLYOLEFINS Albert J. Shmidl, Crosby, and Leroy C. Jennings, Baytown, Tex., assignors to Esso Research and Engineering Company No Drawing. Filed June 25, 1965, Ser. No. 467,124

Int. Cl. D06p 3/00 US. Cl. 8--176 9 Claims ABSTRACT OF THE DISCLOSURE The present invention relates to the dyeing of polyolefins. More particularly, the present invention relates to a method of improving the dye uptake of a polyolefin containing dyesites and to a composition and a fiber produced therefrom which is surprisingly susceptible to treatment by acid, dispersed and premetallized dyes. More specifically, the present invention relates to the pretreatment of a dyeable polyolefin fiber by contact with a penetrant so as to produce a polymer fiber which is more susceptible to treatment with the dyeing materials in an aqueous dyebath. The present invention is also applicable to dyeing the surface of large, molded artic es.

One of the objectives of the polyolefin industry has been to produce fibers which are susceptible to treatment in the same manner as competing fibers when used in woven goods. The commercial practice is for the raw fibers to be spun and woven before being submitted to a dyebath, so that a woven fabric is first obtained prior to dyeing. If the results of the dyebath are unsatisfactory for any reason, the fabric can be bleached and redyed by the manufacturer.

If polyolefins are to compete in the market with natural and synthetic fibers, they must be prepared in such a manner as to be susceptible to dyeing and bleaching as outlined above.

Polyolefins contain only hydrogen and carbon and thus provide no naturally occurring dyesites for retaining a dye in the polymer. It has been proposed that certain pigments be blended with the polyolefin prior to spinning, so that a deep color could be introduced throughout the fiber. This, however, has the disadvantage of making it impossible for the dyer to bleach and redye the fabric, since the pigments within the fiber cannot be bleached.

There are several ways in which dyesites can be placed inside the polymer fiber. First, dyesites can be incorporated by copolymerization of a material with the monomer in order to incorporate the dyesite into the structure of each polymer chain. A second manner in which the dyesite can be incorporated is by physically blending with the homopolymer a material which does contain dyesites. A third manner of incorporating dyesites within a polyolefin fiber is by graft polymerization, such as the polymerization of styrene and maleic anhydride upon the chain of a polypropylene homopolymer.

The net result of all of these attempts to introduce reactive dyesites into the polyolefin itself is to distribute dyesites throughout the fiber. From the standpoint of economics, it is usually desirable to keep the concentration of these dyesites at a practical minimum. Where nitrogen is utilized as the dyesite, the nitrogen concentration by weight should usually be from .05 to 0.5 wt. percent. Nitrogen levels above 0.5 wt. percent can be used, but are not as economically attractive as the lower levels. At these low concentrations, there is a real problem involved in attempting to reach the dyesites with the dye in its aqueous dyebath. Only a small portion of the dyesites will appear at the surface of the fiber, and those which are internal of the fiber cannot be contacted unless the dye itself penetrates into the fiber.

The present invention is based on the discovery that,

by dipping or spraying a dyeable polyolefin fiber with a penetrant which dissolves in the polymer, the susceptibility of the dyeable fiber to acid, dispersed and premetallized dyes is greatly improved.

It is believed that the penetrant softens the noncrystalline area of the polymer fiber, and allows the penetration of the dye into the noncrystalline area to give a deep dyeing of the fiber. The penetrant also may act as a dispersion breaker in order to transfer the premetallized dye and dispersed dye from the aqueous bath onto the surface of the fiber itself. Thus, in a twofold manner, the penetrant pretreatment aids and assists in transferring the dye into contact with the dyesites both on the surface of and within the inerior of a dyeable polyolefin fiber.

Before proceeding to a specific discussion of the manner in which the present invention is carried out, and the characteristics of the product thereof, it should be understood that the following terms wherever used in the present application have the meanings set forth below:

The term fiber shall mean a filament, drawn or undrawn, in the'form of discrete filaments, yarn, or woven fabric material.

The term polyolefin shall mean a solid hydrocarbon polymer, stabilized or unstabilized, containing poly-a-olefins, such as polyethylene, polypropylene, polyisobutene, poly-l-butene, etc.; polydiolefins, such as poly-1,4-butadiene, etc.; and other polymers, such as polystyrene, etc., either as the homopolymer, as a copolymer with a dyesite-containing material, as a blend of homopolymers (for example, polyethylene and polypropylene), as an olefinic copolymer, such as ethylene-propylene random copolymer, ethylene-propylene block copolymer, etc., including ethylene-propylene rubber.

The term dyesites refers to a reactive portion of the polymer which aids in retaining the dye to be used, and is preferably an amino nitrogen.

The term dyesite additive refers to a material containing dyesites which is blended with the homopolyolefin in order to provide dyesites.

The term penetrant shall mean a normally liquid hydrocarbon capable of dissolving into at least the surface portion of a dyeable polyolefin to aid in conducting a dye into the body of the polyolefin, and of sufiiciently low volatility that at least an effective amount will remain dissolved in the dyeable polyolefin under dyeing conditions.

The term dye is used as inclusive of acidic, dispersed and premetallized dyes. The premetallized dye is preferred.

The term dyeable polyolefin shall refer to those materials described below.

TYPES OF DYEABLE POLYOLEFINS The polyolefins to which the present invention is particularly directed are those which basically contain only hydrogen and carbon, such as polyethylene, polypropylene, ethylene-propylene copolymers, polyisobutene, polyisoprene, etc. As such they are not dyeable, since they contain no dyesites. Dyesites may be chemically incorporated by copolymerizing the olefin monomers with 3 small amounts of dyesite-containing monomers. That is, using polypropylene as an example, both propylene and a dyesite-containing monomer (such as an alkenyl amine) may be introduced into the polymerization zone to obtain a polymer which has dyesites as part of the polymer structure. This type of dyeable polypropylene is exemplified by a propylene-N,N-diisopropyl-7-octeny1amine copolymer containing 0.06 wt. percent nitrogen. Alternatively, the dyesite-containing monomer may be grafted onto the polypropylene after polymerization, as exemplified by polypropylene with polyvinylpyridine en grafted thereupon. Other variants include physical blends of polymers (such as polypropylene) with materials containing dyesites, such as polymers containing reacted dyesites (similar to those described above) or with other organic or inorganic materials which provide such dyesites. The relative proportions in these blends will depend on a balancing of a number of factors, including the effect of the blendstock on polymer properties, intensity of color required, efficiency of dyesite additive, etc. The particular additive to be used will depend on the type of dye to be employed, the use to which the dyed material will be put, etc.

All of these modified fibers are referred to herein as dyeable polyolefins. The process of the present invention is equally applicable to films and fibers, drawn and undrawn, which are made from resins of the dyeable polyolefins.

PENETRANTS The dyeable polyolefin is treated with a penetrant as aforesaid. The penetrant can be alkyl-substituted or unsubstituted one and two-ring naphthenes, and partially ring-unsaturated derivatives thereof, such as Decalin, Tetralin, cyclohexane, cyclohexene, and lower alkyl-substituted derivatives thereof. If substituted derivatives are employed, they preferably should have no more than three substituent alkyl groups of three or less carbon atoms each or the hydrocarbon will tend to be a solid at moderate temperatures.

Other penetrants are parafiins and linear olefins, normal or branched, having from 6 to 12 carbon atoms, and aromatic hydrocarbons, unsubstituted or lower alkyl substituted, having one or two rings and having a total of from 6 to 12 carbon atoms. Xylenes, in particular, should be suitable.

Decalin, Tetralin, cyclohexane, and cyclohexene are preferred as penetrants.

The penetrants can be used alone or in admixture with one another. Diluents can also be employed, so long as the diluent has no deleterious effect on the polymer or the dyeing operations. Less effective penetrants (such as n heptane) can be used as diluents for more effective penetrants (such as decalin).

Chlorinated hydrocarbon compounds are to be avoided and should not be used either as penetrants or as diluents, since the chlorine has a deleterious effect on the oxidative stability and color stability of the polymer.

High molecular weight plasticizers and viscous white oils should also be avoided.

The amount of penetrant to be used is based upon the weight of dyeable polyolefin involved. In a thin film or fiber, the entire polyolefin is involved and the total weight is used as a basis. Where a molded object is to be dyed, however, the amount of penetrant cannot be based on the total weight but can easily be determined by trial and error in each case.

For films and fibers, the penetrant content of the film or fiber before dyeing should be from 0.5 to 10 parts by weight per hundred parts by weight of dyeable polyolefin. Preferably, about 3 to parts by weight of penetrant are employed for each hundred parts of dyeable polyolefin, since some of the penetrant may be lost by vaporization under the elevated temperature conditions encountered in the dyebath. The dyed fiber will usually contain from 4 0.01 to 1 part by weight of penetrant per hundred parts of dyeable polyolefin.

When used with a diluent, the penetrant should be present in a concentration of at least 10% by volume. In some cases it may be preferred to use the penetrant with no diluent. For example, it is preferred to use cyclohexane with no diluent.

The penetrant may also be employed in a water emulsion, wherein the penetrant comprises a concentration of from 10 to 50 wt. percent in an oil-continuous phase. The emulsion is obtained and maintained by employing suitable well-known surfactant emulsifiers.

DYES

Many dyes are suitable for dyeing the treated polymer.

Acidic dyes include Erio Anthracene Blue ZGC (CI 62055) and Eric Anthracene Rubine 3GP.

Disperse dyes include Carbolan Green 5G5, Celenthrene Blue 26 (CI 62500), and Carbolan 2GS.

Premetallized dyes include Vialon Orange RR, Vialon Orange R, Irgalan Yellow GL, and Vialon Violet RR. The structure of premetallized dyes, particularly the Irgalan dyes, has been discussed in detail by Schetty in The Irgalan Dyes-Neutral-dyeing Metal-Complex Dyes, published in the December 1955 issue of the Journal of the Society of Dye Chemists. Other well-known premetallized dyes are disclosed in the Color Index, such as Atalan Pink BN (CI 18810) and Supralan Yellow NR (CI 18690), both of which are chromium complexes, and Capracyl Yellow RN (CI 11700) which is a cobalt complex.

Each dye is employed in accordance with the instructions provided by the manufacturer. Generally, they are all used in a hot aqueous dyebath. The premetallized dyes are employed in an aqueous dispersion, being in a concentration of 1.0 to 5.0 wt. percent OWF (i.e., based on the weight of the fiber to be dyed in that bath). An emulsifying agent such as Triton X- is commonly employed to maintain the dispersion. The dyebath is kept at a temperature of 100 F. to 212 F., and the fabric is contacted with the dyebath for a period of time determined by the type of fiber employed in the fabric, the type of dye employed, the depth of color desired, the dye concentration, etc. The pH will vary, depending on the particular dye being employed.

PRETREATMENT OF POLYMER The dyeable polyolefin, preferably in the form of a fabric woven from drawn fibers thereof, is contacted in a pretreatment zone with a penetrant under conditions chosen to dissolve from 0.5 to 10 parts by weight of penetrant in every 100 parts by weight of polyolefin fiber, preferably from 4 to 8 parts by weight. This contacting can be accomplished by spraying or immersing the fabric with the chosen penetrant.

Where the penetrant is to be sprayed upon the fabric, the penetrant is employed at a temperature of 40 F. to F. (preferably at 75 F.), and at a spray treat rate of from 0.5 to 20 (preferably 10) pounds of penetrant per 100 pounds of fabric. Above 15 pounds per 100 pounds the penetrant merely runs immediately off of the fabric. The fabric may be shaken, blotted, or wiped to remove excess penetrant after allowing from 5 to 60 minutes for penetration into the fibers. Alternatively, the fabric may be hung and allowed to drip until the excess penetrant has been removed. The excess can also be removed by centrifuging, pressing or other suitable means to lower the amount of penetrant in the fiber to the desired amount.

If the fabric is immersed in the penetrant, a temperature of 40 F. to 150 F. (preferably F.) is maintained and the fabric residence time in the penetrant bath is from 5 to 60 minutes. Atmospheric pressure is preferred, but may suitably range from 0 to 50 p.s.i.g.

7 COPOLYMERS Examples 11 2 The fibers used in these examples were prepared from a propylene: N,N-diisopropyl-7-octenyl amine copolymer, containing various levels of nitrogen. They were dyed with dispersed dyes such as Carbolan Brilliant Green 568 and Carbolan Brilliant Blue 2GS, premetallized dyes, such as Irgalan Yellow GL, Vialon Fast Violet RR, Vialon Fast Orange R and Vialon Fast Orange RR, and acid dyes such as Erio Anthracene Brilliant Blue 2GC. At lower nitrogen levels, a marked increase in dye uptake was observed. At nitrogen levels above about 3%, sufficient dyeability was obtained without penetrant pretreatment, but the physical properties of the fiber were less desirable.

Examples 1-4 illustrate the use of an acid dye.

Example 1 A fiber was prepared from the copolymer containing 0.04 wt. percent nitrogen. It was dyed with Erio Anthracene Brilliant Blue 2GC, both with and without a pre treatment With Decalin. The Decalinpretreated sample was markedly superior to the untreated sample in dye uptake.

Example 2 A fiber diameter was prepared from the copolymer containing 0.06 wt. percent nitrogen. It was dyed with Erio Anthracene Brilliant Blue 2GC both with and without a pretreatment with Decalin. The Decalin-pretreated sample was markedly superior to the untreated sample in dye uptake.

Example 3 The dyeing run of Example 2 was repeated, substituting for the Decalin a penetrant consisting of 25 'vol. percent Decalin and 75 vol. percent n-heptane. Again, the treated sample was markedly superior to the untreated sample in dye uptake.

Example 4 A fiber diameter was prepared from the copolymer having 0.08 wt. percent nitrogen. It was dyed with Erio Anthracene Brilliant 2GC both with and without Decalin pretreatment. The Decalin-pretreated sample was markedly superior to the untreated sample in dye uptake.

Examples 5-8 illustrate the use of a dispersed dye.

Example 5 The same fiber as in Example 2, containing 0.06 wt. percent nitrogen, was dyed with Carbolan Brilliant Green SGS both with and without Decalin pretreatment. The Decalin-pretreated sample was markedly superior to the untreated sample in dye uptake.

Example 6 The dyeing run of Example 5 was repeated, substituting for the Decalin a penetrant consisting of vol. percent Decalin and 75 vol. percent n-heptane. The pretreated sample was markedly superior to the untreated sample in dye uptake.

Example 7 The same fiber as in Example 2, containing 0.06 wt. percent nitrogen, was dyed with Carbolan Brillant Blue 2GS both with and without Decalin pretreatment. The Decalin-pretreated sample was markedly superior to the untreated sample in dye uptake.

Example 8 The dyeing run of Example 7 was repeated, substituting for the Decalin a penetrant consisting of 25 vol. percent Decalin and 75 vol. percent n-heptane. The pretreated sample was markedly superior to the untreated sample in dye uptake.

Examples 9-12 illustrate the use of a pre-metallized dye.

Example 9 The same fiber as in Example 2, containing 0.06 wt. percent nitrogen, was dyed with Irgalan Yellow GL both with and without Decalin pretreatment. The Decalinpretreated sample was markedly superiod to the untreated sample in dye uptake.

Example 10 The dyeing run of Example 9 was repeated, substituting for the Decalin a penetrant consistng of 25 vol. percent Decalin and vol. percent n-heptane. The pretreated sample was markedly superior to the untreated sample in dye uptake.

Example 11 A fiber was prepared from the copolymer having 0.3 wt. percent nitrogen. It was dyed with Vialon Fast Violet RR both with and without Decalin pretreatment. The Decalin-pretreated sample was markedly superior to the untreated sample in dye uptake.

Example 12 The same fiber as in Example 11, containing 0.3 wt. percent nitrogen, was dyed with Vialon Fast Orange R both with and without Decalin pretreatment. The Decalin-pretreated sample was markedly superior to the un treated sample in dye uptake.

BLENDS Examples 1317 The fibers used in these examples were prepared from two types of polymer blends. Type I is a blend of wt. percent homopolypropylene with 10 Wt. percent of a copolymer of propylene and N,N-diisopropyl-7-octenyl amine. This first polymer blend had a nitrogen content of 0.06 wt. percent. Type II is a blend of 97 wt. percent homopolypropylene and 3 wt. percent polyvinyl-pyridine, giving a nitrogen content of 0.4 wt. percent.

The fibers were dyed with acid dyes such as Erio Anthracene Brilliant Blue 2GC and Erio Anthracene Rubine 3GP and premetallized dyes such as Vialon Fast Violet RR, Vialon Fast Orange R, Vialon Fast Orange RR, Irgalan Yellow 2RL, and Lanasyn Brown 2RL.

Comparative runs using Decalin and cyclohexene as penetrants showed in each case a marked improvement in dye uptake when penetrant pretreatment was employed.

Examples 1316 illustrate the use of acid dyes.

Example 13 A fiber was prepared from the Type I blend of homopolypropylene and the propylene-N,N-diisopropyl-7-octenyl amine copolymer. It contained 0.06 wt. percent nitrogen. It was dyed with Erio Anthracene Brilliant Blue 260 both with and without a pretreatment with Decalin. The Decalin-pretreated sample was markedly superior to the untreated sample in dye uptake.

Example 14 The dyeing run of Example 13 was repeated, substituting for the Decalin a eyclohexane penetrant. The treated sample was markedly superior to the untreated sample in dye uptake.

Example 15 The same fiber in Example 13 was dyed with Erio Anthracene Rubine 3GP both with and without a pretreatment with Decalin. The Decalin-pretreated sample was markedly superior to the untreated sample in dye uptake.

Example 16 The dyeing run of Example 15 was repeated, substituting for the Decalin a eyclohexane penetrant. The treated sample was markedly superior to the untreated sample in dye uptake.

Examples 17-26 illustrate the use of premetallized dyes.

Example 17 The same fiber as in Example 13 was dyed with Vialon Fast Violet RR both with and without Decalin pretreatment. The Decalin-pretreated sample was markedly superior to the untreated sample in dye uptake.

Example 18 The same fiber as in Example 13 was dyed with Vialon Fast Orange RR both with and without Decalin pretreatment. The Decalin-pretreated sample was markedly superior to the untreated sample in dye uptake.

Example 19 The same fiber as in Example 13 was dyed with Irgalon Yellow 2RL both with and without a Decalin pretreatment. The Decalin-pretreated sample was markedly superior to the untreated sample in dye uptake.

Example 20 The dyeing run of Example 19 was repeated, substituting cyclohexane for the Decalin penetrant. The pretreated sample was markedly superior to the untreated sample in dye uptake.

Example 21 s The same fiber as in Example 13 was dyed with Vialon Fast Orange R both with and without Decalin pretreatment. The Decalin-pretreated sample was markedly superior to the untreated sample in dye uptake.

Example 22 The dyeing run of Example 21 was repeated, substituting cyclohexane for the Decalin penetrant. The pretreated sample was markedly superior to the untreated sample in dye uptake.

Example 23 The same fiber as in Example 13 was dyed with Lanasyn Brown 2RL both with and Without Decalin pretreatment. The Decalin-pretreated sample was markedly superior to the untreated sample in dye uptake.

Example 24 The dyeing run of Example 23 was repeated, using Vialon Fast Violet RR as the dye. The pretreated sample was markedly superior to the untreated sample in dye uptake.

Example 25 A fiber was prepared from the Type II blend of homopolypropylene and polyvinylpyridine. It contained 0.4 wt. percent nitrogen. It was dyed with Vialon Fast Orange RR both with and without a Decalin-pretreatment. The Decalin-pretreated sample was markedly superior to the untreated sample in dye uptake.

Example 26 The same fiber as in Example 25 was dyed with Vialon Fast Violet RR both with and without Decalin pretreatment. The Decalin-pretreated sample was markedly superior to the untreated sample in dye uptake.

Example 27 illustrates the use of an acid dye.

Example 27 The same fiber as in Example 25 was dyed with Erio Anthracene Brilliant Blue ZGC both with and without a Decalin pretreatment. The Decalin-pretreated sample was markedly superior to the untreated sample in dye uptake.

GRAFI POLYMERS Examples 28-30 The fibers used in these examples were prepared from a graft copolymer of polyvinylpyridine on a homopolypropylene backbone. Various levels of nitrogen were obtained. The graft copolymers were dyed with a dispersed dye-Celenthrene Fast Blue 2G.

Example 28 A fiber was prepared from a graft copolymer as de-' scribed above, having a nitrogen content of 0.04 wt. percent. It was dyed with Celenthrene Fast Blue 2G, both with and without a Decalin pretreatment. The Decalinpretreated sample was markedly superior to the untreated sample in dye uptake.

Example 29 Example 30 A fiber was prepared from a graft copolymer as described above, having a nitrogen content of 0.35 wt. percent. It was dyed with Celenthrene Fast Blue 26, both with and without a Decalin pretreatment. The Decalinpretreated sample was markedly superior to the untreated sample in dye uptake.

As can be seen from the table above, the susceptibility of the fiber samples to dyeing is increased by the penetrant pretreatment. Particularly, the premetallized dyes show an outstanding susceptibility to the Decalin treated dyeable polypropylene as compared to the untreated 'po1ypropylene. Further, the use of a cyclohexane penetrant has been shown to be advantageous.

Having disclosed the invention and having set forth preferred modes of practicing the same, what we desire to cover by Letters Patent should be limited not by the specific examples herein given, but rather only by the appended claims.

We claim:

1. A method of dyeing a fiber made of a polyolefin which contains nitrogen dyesites, which comprises in a pretreating zone, contacting parts by weight of said shaped article with a penetrant chosen from the group consisting of Decalin, Tetralin, cyclohexane and cyclohexene, under conditions chosen to leave from 0.5 to 10 parts by weight of said penetrant dissolved at the surface of said polyolefin,

said conditions including a temperature within the range from 40 F. to F., and thereafter, in a dyeing zone, treating said shaped article under dyeing conditions with a dye chosen from the group consisting of acid dyes, dispersed dyes and premetallized dyes.

2. A method in accordance with claim 1 wherein the polyolefin is polypropylene.

3. A method in accordance with claim 2 wherein the penetrant is Decalin, and from 4 to 8 parts by weight of Decalin are used per hundred parts by weight of polypropylene.

4. A method in accordance with claim 3 wherein the dye is a premetallized dye.

5. A method in accordance with claim 1 wherein the pretreatment contacting is carried out by immersing the polyolefin in the penetrant at a pressure of 0 to 50 p.s.i.g. and for a time from 5 to 60 minutes.

and the dyeing step is carried out within 24 hours after the pretreating step is completed.

6. A method in accordance with claim 5 wherein the polyolefin is polypropylene.

7. A method in accordance with claim 6 wherein the penetrant is Decalin.

3,533,731 1 1 1 2 8. A method in accordance with claim 7 wherein the FOREIGN PATENTS A i iift h d i c i mce with claim 8 wherein from 921119 3/1963 Great i i 4 to 8 parts by weight of Decalin are used per hundred 940,716 10/1963 Great Bntam' parts by Weight of 5 GEORGE F. LESMES, Primary Examiner Referen s Cited B. BETTIS, Assistant Examiner UNITED STATES PATENTS 2,329,113 4/1953 Wehr. US 3,123,146 4/1964' Bianco et a1. 10 3 94, 130; 260-33.6, 33.1, 373, 395, 397