EP0043410B1

EP0043410B1 - Process for producing adhesive active polyester yarn and product

Info

Publication number: EP0043410B1
Application number: EP19810102812
Authority: EP
Inventors: Kalidas Chakravarti; Kimon Constantine Dardoufas
Original assignee: Allied Corp
Current assignee: Allied Corp
Priority date: 1980-05-29
Filing date: 1981-04-13
Publication date: 1985-07-24
Also published as: JPS5721572A; CA1164406A; EP0043410A2; DE3171457D1; EP0043410A3

Description

Background of the invention

Field of the invention

The present invention relates to a process for producing adhesive active polyester yarn. More particularly, the present invention relates to a process for producing adhesive active polyester, preferably polyethylene terephthalate, yarn wherein the yarn is coated with an aqueous emulsion which contains an epoxy silane, and after drawing, the yarn is exposed to ultraviolet radiation. The present invention also relates to the yarn produced in accordance with the process. The yarn preferably is twisted into tire cords for the construction of pneumatic passenger tires and results in excellent adhesion of tire cord to rubber.

Description of the prior art

Polyester tire cord requires the application of an adhesive layer to obtain bonding to the rubber. Two types of adhesive systems, a single dip and a double dip adhesive system, have been developed to meet this need.
In the double dip system, polyester cords are treated with a first dip which is a dispersion of a phenol-blocked methylene bisphenylene diisocyanate, an epoxy resin, wetting agents and water. The treated cord is cured, then treated with a second dip of resorcinol-formaldehyde-latex and cured again.
In the single dip system, the adhesive layer is applied to the polyester yarn in an overfinish subsequent to drawing of the yarn. The polyester yarn is plied into cords which are treated with a resorcinol-formaldehyde latex dip and cured. The need for the blocked diisocyanate dip in cord processing is eliminated by this system. Low carboxyl polyester yarn treated with this system has very good ammonolytic and hydrolytic stability, but has poor adhesion to rubber when made into tire cord. Further, while regular carboxyl polyester yarn shows acceptable adhesion to rubber under normal curing temperatures, a reduction of the curing temperatures has been found to adversely affect adhesion to rubber.
The present invention significantly improves yarn to rubber adhesion of polyester tire cords treated with the single dip system for (a) low carboxyl polyester yarn wherein normal curing temperatures are utilized, and (b) regular carboxyl polyester yarn wherein reduced curing temperatures are utilized.
The closest prior art is believed to be U.S. Patents 3,642,518 to Miki et al., 3,730,892 to Marshall et al., and 4,054,634 to Marshall et al., all of which disclose treating polyester material with a silane having the structural formula of the silane of the present invention to promote adhesion to rubber, 3,672,977 to Dardoufas which discloses an overfinish composition similar to that of the present invention but without the silane, and British Patent Specification 1,228,173 to Jervis et al. which discloses the pretreatment of a polyester reinforcing textile by exposure to ultraviolet radiation to improve the level of adhesion to rubber.

Summary of the invention

The present invention provides an improvement in a process for the production of polyester yarn involving spinning and drawing steps. The present invention further provides polyester yarn treated in accordance with the process.
The improvement comprises: exposing the yarn subsequent to the drawing step to ultraviolet radiation; and treating the yarn with a finish composition which comprises water and a silane having the structural formula
wherein n=2 to 5.
The step of exposing the yarn to ultraviolet radiation may occur either prior to or subsequent to the step of treating the yarn with the finish composition.
The ultraviolet radiation preferably has wave lengths between 200 and 400 nanometers and a peak wave length of 253 nanometers. The time period for exposure of the yarn to ultraviolet radiation is at least 0.3 second, preferably 0.3 to 7 seconds.
The finish composition may comprise 50 to 98 weight percent of water and 2 to 50 weight percent of the silane. When these form the major finish composition ingredients and the finish composition is to be applied by means of a conventional lube roll, it is preferred that a small amount, for example 0.1 weight percent, of a nonionic wetting agent be incorporated in order to wet the lube roll; Triton X-100, Rohm & Haas Company's trademark for polyoxyethylene 9-10 octylphenol, is satisfactory.
It is preferred that the finish composition be an overfinish composition which comprises an oil-in-water emulsion wherein the non-aqueous portion comprises 50 to 70 weight percent of hexadecyl stearate, 3 to 9 weight percent of glycerol monoolerate, 2 to 8 weight percent of decaglycerol tetraoleate, 5 to 12 weight percent of ethoxylated tall oil fatty acid, 5 to 15 weight percent of sulfonated glycerol trioleate, 1 to 10 weight percent of ethoxylated alkyl amine, and 2 to 45 weight percent of the silane. The preferred silane is gamma-glycidoxypropyltrimethoxysilane. The yarn is preferably treated with a sufficient amount of the overfinish composition that (a) 0.4 to 1.0 weight percent based on the weight of the yarn of the non-aqueous portion of the overfinish composition is added, and (b) 0.05 to 0.2 weight percent based on the weight of the yarn of the silane is added. Alternatively, the overfinish composition can comprise 7 to 50 weight percent of the silane, 5 to 20 weight percent of dimethyl polysiloxane emulsion, and the balance water.
The present invention also provides, in a process for the production of polyester yarn involving spinning and drawing steps, the improvement which comprises exposing the yarn subsequent to the drawing step for a time period of at least 0.3 second to ultraviolet radiation having a wave length between 200 and 400 nanometers; and treating the yarn with an overfinish composition comprising 60 to 90 weight percent of water and 10 to 40 weight percent of an oil portion; the oil portion comprising 50 to 70 weight percent of hexadecyl stearate, 3 to 9 weight percent of glycerol monooleate, 2 to 8 weight percent of decaglycerol tetraoleate, 5 to 12 weight percent of ethoxylated tall oil fatty acid, 5 to 15 weight percent of sulfonated glycerol trioleate, 1 to 10 weight percent of ethoxylated alkyl amine, and 2 to 45 weight percent of a silane having the structural formula
wherein n=2 to 5.
Low carboxyl polyester yarn is defined as having 8 to 18 carboxyl end groups (meq./kg.). Regular carboxyl polyester yarn is defined as having 19 to 30 carboxyl end groups (meq./kg.).
The strip adhesion test utilized in illustrating the present invention is defined in U.S. Patent 3,940,544 to Marshall et al.

Description of the preferred embodiment

In order to demonstrate the invention, the following examples are given. They are provided for illustrative purposes only and are not to be construed as limiting the scope of the invention, which is defined by the appended claims. Specifically, it is believed that the finish composition can be applied either as a spin finish during spinning or as an overfinish subsequent to drawing of the yarn. Further, it is believed that there are other spin finishes which would perform as satisfactorily as the one detailed (see Table I). It is also believed that there are other compatible non-aqueous components which would perform as satisfactorily in the overfinish composition as the ones detailed as additional to the silane. In these examples, parts and percentages are by weight unless specified otherwise.
The yarns of this invention can be processed by any spin draw process or spinning and separately drawing process available to the art and the patent and technical literature, using any suitable polyester.
The preferred polyesters are the linear terephthalate polyesters, i.e., polyesters of a glycol containing from 2 to 20 carbon atoms and a dicarboxylic acid component containing at least 75 percent terephthalic acid. The remainder, if any, of the dicarboxylic acid component may be any suitable dicarboxylic acid such as sebacic acid, adipic acid, isophthalic acid, sulfonyl-4,4'-dibenzoic acid, or 2,8-di-benzofuran-dicarboxylic acid. The glycol may contain more than two carbon atoms in the chain, e.g., diethylene glycol, butylene glycol, decamethylene glycol, and bis-1,4-(hydroxymethyl)cyclohexane. Examples of linear terephthalate polyesters which may be employed include poly(ethylene terephthalate), poly(butylene terephthalate), poly(ethylene terephthalate/5-chloroisophthalate) (85/15), poly(ethylene terephthalate/5-[sodium sulfo]isophthalate) (97/3), po)y(cyciohexane-1,4-dimethy)ene terephthalate), and poiy(cyciohexane-1,4-dimethy)ene terephthalate/hexahydro terephthalate) (75/25).

Example 1 (Comparative)

For comparative testing, a polyethylene terephthalate yarn having 11±1 carboxyl end groups was prepared substantially in accordance with one procedure described in U.S. Patent 3,672,977 to Dardoufas, i.e., a 1000 denier (111 tex) 192 filament yarn was prepared comprised of polyethylene terephthalate filaments treated with 0.45 percent based on the weight of the yarn of a liquid spin finish identified as spin finish A in Table I. Drawing performance of the yarn was excellent. Finish oil on the fiber was 0.15 to 0.25 percent.
The yarn was passed through a chamber enclosing two 4-tube layers with off-set centers of high intensity lamps of the germicidal type having wave length of 200 to 300 nanometers, with peak wave length at 253 nanometers. The lamps were approximately 83.8 centimeters (33 inches) in length and can be obtained from the Ultradynamics Corporation, Santa Monica, California. The yarn made six passes through the chamber, each pass being centered at a distance of 1 centimeter between three of the tubes so that high intensity ultraviolet radiation fell on all sides of the yarn. The lamps were found to provide maximum efficiency at a temperature near 37.8°C (100°F). The yarn was exposed to the ultraviolet radiation for a total of 7 seconds.
To this yarn a secondary finish, or overfinish, identified as overfinish A of Table II, was applied at a 3 percent total wet pickup to achieve a total oil on yarn level of 1.0 percent. The yarn was then twisted into 3-ply cords having 9x9 twists per inch (2.54 cm). Each cord was treated with a conventional non-ammoniated resorcinol-formaldehyde-latex dip comprising vinyl pyridine latex, resorcinol, formaldehyde, sodium hydroxide and water, at 4.5 percent total solids pickup based on the weight of the cord. The cords were then cured at treating condition 3 of Table III. The treated cords were subjected to the strip adhesion test, results of which are presented in Table IV.

Example 2 (Comparative)

The procedure of Example 1 was repeated with the following changes: The yarn was not exposed to ultraviolet radiation; and the yarn was overfinished at room temperature with overfinish B of Table II. Results of adhesion testing are presented in Table IV.

Examples 3-5

The procedure of Example 1 was repeated in each of Examples 3 through 5 with the following changes: The yarn was exposed to the ultraviolet radiation for a period of 0.3, 3 and 7 seconds, respectively, in Examples 3 through 5; and the yarn was overfinished at room temperature with overfinish B of Table II. Results of adhesion testing are presented in Table IV.

Examples 6 and 7

The procedure of Example 1 was repeated with the following changes: The yarn was not exposed to ultraviolet radiation in Example 6 while in Example 7, the yarn was exposed to ultraviolet radiation for a period of three seconds; and in both examples, the yarn was overfinished at room temperatures with overfinish C of Table II. Results of adhesion testing are presented in Table IV.

Examples 8-13

Polyethylene terephthalate yarn having 24±1 carboxyl end groups was prepared in accordance with the procedure of Example 1 in Examples 8 through 13, utilizing the spin finishes, overfinishes, ultraviolet treatment and treating conditions specified in Table IV. Results of adhesion testing are also presented in Table IV.

Examples 14-19

Polyethylene terephthalate yarn having 24±1 carboxyl end groups was prepared in accordance with the procedure of Example 1 in Examples 14 through 19, utilizing the spin finishes, overfinishes, ultraviolet treatment and treating conditions specified in Table IV; however, the step of exposing the yarn to ultraviolet radiation followed the application of overfinish to the yarn in those examples (15, 16, 18 and 19) which included both of these steps. Results of adhesion testing are presented in Table IV.

Conclusions

A comparison of Examples 1 through 7 shows the critical importance to adhesion for low carboxyl polyethylene terephthalate yarn of both exposing the yarn to ultraviolet radiation and treating the yarn with an aqueous finish composition containing an epoxy silane as previously described. The adhesion ratings were especially excellent for Example 5.
A comparison of Examples 8 through 19 shows the critical importance to adhesion for regular carboxyl polyethylene terephthalate yarn of both exposing the yarn to ultraviolet radiation and treating the yarn with an aqueous finish composition containing an epoxy silane as previously described. In examples 9, 11 and 13, the polyethylene terephthalate yarn was exposed to ultraviolet radiation prior to treatment with an aqueous overfinish composition containing the epoxy silane, while in Examples 15, 16, 18 and 19, the polyethylene terephthalate yarn was treated with an aqueous overfinish composition containing the epoxy silane prior to exposure to ultraviolet radiation. The adhesion ratings were good in both instances. Further, it can be seen that substantially lower curing temperatures (treating conditions of Table III) can be utilized with the regular carboxyl yarn; this results in both energy savings and reduced plant emissions.
Alternative sources of ultraviolet radiation can be used. For example, medium wave length (280 to 400 nanometers) fluorescent sun lamp Model FS-40 available from Westinghouse Corporation is suitable. The intensity of ultraviolet radiation is expressed in micro-watts per square centimeter at a given distance. The total ultraviolet energy emitted from all sides of the ultraviolet lamp is expressed in watts. The total exposure is a product of energy, time and area which is expressed as ultrads (microwatt seconds per square centimeter). The same number of ultrads can be achieved with a short exposure time at a high intensity of ultraviolet radiation, or a long exposure at a low intensity of ultraviolet radiation. Exposures of the polyethylene terephthalate yarn to ultraviolet radiation for a period of up to 15 minutes showed virtually no loss of yarn breaking strength and other yarn physical properties, but did show improvement in adhesion to rubber when treated with the overfinish system as described in this specification.

Claims

1. A process for the production of polyester yarn comprising the steps of:

(a) spinning the yarn;

(b) drawing the yarn; and

(c) treating the yarn with a finish composition which comprises water and a silane having the structural formula

wherein n=2 to 5, characterized by, in combination, (1) exposing the yarn subsequent to the drawing step to ultraviolet radiation.

2. A process according to claim 1 wherein step (1) occurs prior to step (c).

3. A process according to claim 1 wherein step (1) occurs subsequent to step (c).

4. A process according to claim 1 wherein the silane is gamma-glycidoxypropyltrimethoxysilane.

5. A process according to claim 1 wherein the finish composition comprises 50 to 98 weight percent of water and 2 to 50 weight percent of the silane.

6. A process according to claim 1 wherein the finish composition is an overfinish composition which further comprises a dimethyl polysiloxane emulsion.

7. A process according to claim 1 wherein step (1) occurs for at least 0.3 second to ultraviolet radiation having a wave length between 200 and 400 nanometers; and wherein the finish composition is an overfinish composition comprising 60 to 90 weight percent of water and 10 to 40 weight percent of an oil portion, the oil portion comprising 50 to 70 weight percent of hexadecyl stearate, 3 to 9 weight percent of glycerol monooleate, 2 to 8 weight percent of decaglycerol tetraoleate, 5 to 12 weight percent of ethoxylated tall oil fatty acid, 5 to 15 weight percent of sulfonated glycerol trioleate, 1 to 10 weight percent of ethoxylated alkylamine, and 2 to 45 weight percent of a silane having the structural formula

wherein n=2 to 5.

8. A process according to claim 7 wherein the silane is gamma-glycidoxypropyltrimethoxysilane.