MXPA97010387A - Training of nanocompuesto de polimero by synthesis of emuls - Google Patents

Abstract

The formation of a nanocomposite by emulsion polymerization is described. The invention includes nanocomposite latex, a solid nanocomposite of a layered silicate mineral interspersed with an emulsion polymer and mixtures of solid nanocomposite with other polymer

Description

FORMATION OF NANOCOMPOSIT OF POLYMER THROUGH SYNTES IS DE EMULS ION Field of the Invention This invention relates to composite materials which have a reduced permeability of small molecules, such as air, and which have improved mechanical properties. More particularly this invention relates to silicates in layers interspersed with an emulsion polymer Background of the Invention Layered clay minerals such as monomethyrylonite are composed of silicate layers approximately 1 nanometer thick. Dispersions of layered materials in polymers are often referred to as nonocompuesot.

Recently there has been a considerable interest in the formation of nanocomputsto? as a means to improve the mechanical properties of the polymer. s. Without packaging, the minerals ie clay that are incorporated into a polymer matrix do not always result in remarkably improved mechanical properties of the polymer. This may be due to the lack of affinity between the layered silicate materials and the organic polymers. Therefore, the use of ionic interactions has been proposed as a means of inorganizing the clay minerals in a polymer. For this aspect, observe the example of the U.S. Patent 4,889,885 and the U.S. Patent 4,810,734. This type of scope has unfortunately limited its usefulness. In fact, a more direct, simple and economical scope to prepare nanocomposites is highly desirable.

An object of the present invention is to provide a latex comprising a layered silicate intei? Ed with an emulsion polymer. Another object of the present invention is to provide a composite material formed from a layered silicate dispersion latex and an emulsion polymer, the material of which has reduced the permeability to small molecules such as air < = -, and improved the mechanical properties.

These and other objects, features and advantages of the present invention will become more apparent from the description that follows.

Compendium of the Invention In one embodiment of the present invention, a latex comprising water and a layered mineral interspersed with an emulsion polymer is provided.

Another embodiment of the present invention provides a nanocomposite comprising a layered mineral interspersed with an emulsion polymer.

Another aspect of the present invention comprises a mixture of a first polymer with a nanocomposite composed of a layered mineral interspersed with an emulsion polymer.

The process for the production of the latex of the present invention comprises the formation of a dispersion of a layered material in water including an agent for inflating such as the onium salt, by adding a monomer or polimerizable monomers, co or an olefin or diene, with a polymerization initiator for the dispersion, and then the polymerization of the monomer or monomers to form a latex comprising water and a polymer compound. The preparation of this latex still comprises another embodiment of the present invention.

A composition material formed from the latex of the present invention has improved the mechanical properties and reduced the air permeability to small molecules such as air, making it particularly useful, in a range of applications, particularly as a tire liner and as tubes interiors, barriers, films, coatings and the like.

Detailed description Any natural or synthetic layered mineral capable of intercalation can be employed in the present invention; however, layered silicate minerals are preferred. The layered silicate minerals that may be employed in the present invention include the natural and artificial minerals capable of forming the intercalation compounds. Examples that do not limit these minerals include semctite clay, mnontmorillonite, saponite, beidelite, ontronite, hectoria, stevewnsite, vermiculite, and halosite. The one that is > He prefers these is montorilonite.

The inflating agent that is used in the practice of the present invention is any compound capable of interlaying the mineral in layers and thereby increasing the distance between the layers. Particularly, the preferred inflating ingredients are the onium salts of hydrocarbyls represented by the formula A-M + R 1 R 2 R 3 R 4 and A-py + R 4 wherein A- signifies an anion such as the halide, OH-, N03-, S04- and the like; the M means N, S, P; R1, R, R3 and R4 independently means hydrogen alkyl, aryl or allyl groups, which may be the same or different, since at least one of them is other than hydrogen; and Py means the pyridinium group substituted by alkyl or pyridinium.

It will be readily appreciated that some of the aforementioned blowing agents are also emulsifying agents. However, in those instances in which the blowing agent is not an emulsifying agent, preferably the emulsifying agent will be used to carry out the polymerization. Of course, another emulsifying agent can optionally be used even when the blowing agent has emulsifying properties. In any case, the emulsifying agent will be one of those typically used in the emulsion polymerization process. Preferred are cationic emulsifying agents and nonionic emulsifying agents.

The polymers and copolymers referred to herein as emulsion polymers are those formed by emulsion polymerization techniques. Included are polymers based on one or more free radical polymerizable monomers such as the defined monomers and specifically styrene or styrene of paramethyl, butadene, isoprene, chloroprene and acrylonitrile. Particular preference is given to styrene rubber copolymers, that is, copolymers of styrene and butadene, isoprene, chloroprene and acrylonitrile. Especially preferred in the practice of the present invention are homopolymers and copolymers having a glass transition temperature less than about 25 ° C, a weight average molecular number above 5,000 g / mol and especially above of 15, OOOgr / mol. Also the preferred polymers will contain some unsaturation or other reactive sites for the. vulcanization The latex of an intercallable mineral having an emulsion polymer interspersed in the ore is prepared by forming a dispersion of the mineral layered in water and including the inflating agent. Typically, the ore is first dispersed in water by adding from about 0.01 to about 80 gr. from ore to 100 grams of water and preferably from about 0.1 to about 10.0 grams of mineral to 100 grams of water and then vigorously mixing or shearing the ore and water for a sufficient time to disperse the mineral in the water. The hydrocarbonium onium salt is then added to the dispersion, preferably as a water solution and stirring.

The amount of the onium salt used in the process of the present invention depends on the type of material in layers and the monomers that are used, as well as the process conditions. However, in general, the amount of onium salt used will range from the cationic co-exchange capacity of the mineral in layers of approximately 10% to approximately 2,000% of the cation exchange capacity of the mineral in layers.

Then, the polymethylene latex is formed by adding an emulsifying agent to the mineral dispersion, if desired or necessary, the appropriate monomer or monomers and releasing a radical initiator under the conditions of the polymerization of the emulsion. For example, styrene and isoprene are polymerized in the mineral dispersion using a free radical polymerization initiator while stirring the reactors. The copolymerization is typically conducted at a temperature in the range of about 25 ° C to about 100 ° C and for a sufficient time to form the polymer latex, followed by termination of the reaction.

The latex described above can be used to form coatings or films followed by standard techniques used for the formation of these materials. Additionally, the nanocomposite of the layered silicate mineral and the polymer can be recovered by coagulating the latex, and drying the solid compound. The solid compound can then be formed in an inner liner of an inner tire or tubes using conventional processing techniques such as sorting or extrusion followed by tire construction and molding.

In one embodiment of the present invention, the nanocoat is dispersed with another polymer, a styrene rubber copolymer, by mixing a rubber mixer or in an internal mixer. Preferably the nanocomposite will be mixed with a polymer formed from the same monomer or monomers that were used in the formation of the nanocomposite. The amount of the nanocomposite in the polymer will typically be in the range of about 0.1 to about 70% by weight.

In producing the inner liners of the tire, the polymer is mixed with the nanocomposite of this invention, preferably having a molecular weight greater than about 10,000 and some unsaturation or other reactive sites so that it can be vulcanized or crosslinked in the bulk state .

The invention will be understood more clearly by reference to the following examples.

Example 1 A layered silicate, raontmorilonite clay (18gr.), Was mixed with water (450gr.) Which had previously been degassed by means of nitrogen sparge. The mortar was stirred overnight at 23 ° C. The clay was dispersed in the water in an aring mixer for three minutes and then degassed further. Dodecyl trimethyl ammonium bromide (27.7 g) was dissolved in degassed water (250 g) and added to the clay mortar. Isoprepo (35 g.), Styrene (15 g.) And azobisisobutyronitrile (AIBN) (0.25 g.) Were mixed as an initiator and then added to the clay mortar. The mixture was stirred mechanically for 20 hours at a temperature of 23 ° C and for 26 hours at 65 ° C at which time the polymerization was terminated with 5 g. aliquot of a mixture of (0.24 gr.) 2,6-di-tert-butyl-4-methylphenol, (1.6 gr.) hydroquinone, (0.8 gr.) tetrakis (methylene (3,5-di-tert-butyl) -4-hydroxy-hydrocinomethane)) methane and 200 ml of methanol. The net result was the formation of an emulsion containing a layered silicate having an isoprene-styrene copolymer latex interspersed in the layered mineral.

Example A solid nanocomposite was formed from the latex of Example 1 by adding an excess of methanol to the latex, separating the solid from the liquid aqueous phase and washing the solid six times with methanol, followed by drying for about 18 hours at a temperature of 60 °. C under vacuum and for 48 hours at a vacuum of 13CC.

Example 3 A portion of the solid nanocomposite (20 gm) of Example 2 was then melted mixed at 130 ° C in a Brabender mixer for 5 minutes with an isoprene-styrene copolymer (20 gm) which was identically synthesized bolt without clay. The mixture of the nanocomposite and the isoprene-styrene copolymer which does not contain clay is crosslinked by rolling milling the mixture with the stearic acid (1 phr), zinc oxide (3.9 phr) and teramethyl thiuram disulfide (accelerator) ( 1 phr) at 55 ° C for 10 minutes. The mixture was then thermally pressed into 20 thousandths of an inch films and cured for 20 minutes at 130 ° C. The films were tested on a Mocon 2/20 for the transmission of oxygen at 30 ° C. The results are given in Table 1 below. Also shown in Table 1 are the results that were obtained with a film formed of an isoprene-styrene copolymer that had been synthesized identically but without clay. (Comparative example 1).

The properties of uniaxial traction were also measured on specimens a minitraction film using an Instron testing apparatus. The stress and force measurements were carried out at an ambient temperature and an extension ratio of 0.51 mm / min and the results are shown in Table 2. Also shown in Table 2 t is labeled as Comparative Example 1 the properties obtained for a copolymer of isoprene-polyistrene which is synthesized identically to that of Example 1 but without clay.

TABLE 1 Transmission Clay Film cm3xMILS +% oxygen weight m2 x 4 hr Example 3 26.3 4, 138 Example 12, 340 Comparative 1 0 + Mocon 2/20 @ 30 ° C TABLE 2 Voltage Tension Film in Modules the brake the young brake Ipor inch (%) (per square inch) square) Comparative 1 001 2053 E emplo 3 321 497 5018 100% Film: oo% 300% Modules Modules Modules, per inch (per inch (per inch) square) square) Comparative 1 660 901 Example 699 880 1262 Film 400% Energy in Modules the brake [per square inch] Comparative 1 1236 12.1 Example 3 1237 11.3

Claims (25)

1. A latex comprising: water and mineral in layers interspersed with an emulsion polymer.

2. The latex of claim 1, wherein the layered mineral is a natural and synthetic mineral selected from the group consisting of smectite clay, rpontmorilonite, saponite, beidelite, montronite, hectorite, stevensite, vermiculite and halosite.

3. The latex of claim 1, wherein the polymer is formed from a free radical polymerizable olefinic monomer or monomers.

4. The latex of claim 1, wherein the polymer is a styrene-containing copolymer.

5. The latex of claim 4, wherein the copolymer contains a comonomer selected from the group consisting of butadene, isoprene, cloprene and acrylonitrile.

6. The latex is claim 5, wherein the layered material is montmorillonite.

7. A latex comprising: water and a synthetic or natural layered mineral interspersed with a polymer or copolymer, wherein the layered ore is selected from the group consisting of smectite clay, montmorillonite, saptonite, beidelite, montronite, hectorite, estevensite, vermiculite, and halosite and wherein the polymer or copoiimer is formed from a poly-free radical olefinic monomer or monomer.

8. The latex of claim 7, wherein the monomer or monomers are selected from the group consisting of styrene, paramethyl styrene, butadene, isoprene, chloroprene and acrylonitrile.

9. A nanocomposite comprising a mineral in layers interspersed with an emulsion polymer.

10. The nanocomposite of claim 9, wherein the layered mineral is selected from the group consisting of smectite clay, montmorillonite, saponite, beidelite, msntonite, hectorite, estevensite, vermiculite and halosite.

11. The nanocomposite of claim 10, wherein the polymer is formed from a free radical polymerizable olefin monomer or monomers.

12. The nanocomposite of claim 11, wherein the polymer is a copolymer containing styrene.

13. The nanocomposite of claim 12, wherein the styrene-containing copolymer is a styrene or styrene copolymer of paramethyl with a monomer selected from the group consisting of butadene, isoprene, chloroprene and acrylonitrile.

14. The nanocomposite of claim 13, wherein the layered mineral is montruorilonite.

15. A polymer blend comprising: a first polymer and a layered mineral nanocomposite interspersed with an emulsion polymer.

16. The mixture of claim 15, wherein the first and the emulsion polymers are formed from the same monomer or monomers.

17. The mixture of claim 16, wherein the first and the emulsion polymers are copolymers.

18. The mixture of claim 117, wherein the amount of the nanocomposite in the mixture is in the range of about 0.1 to about 70% by weight.

19. The mixture of claim 18, wherein the copolymer is a styrene or styrene copolymer of paramethyl with a monomer selected from butadiene, isoprene, chloroprene and acrylonitrile.

20. A process for the production of a latex that includes a nanocomposite material comprising: disperse the mineral in layers in water to form a dispersion; add an inflating agent to the dispersion; and then the polymerization of a free radical polymerizable olefin monomer or monomers in the presence of the dispersion under emulsion polymerization conditions to form a latex including the nanocomposite material.

21. The process of claim 20, wherein the two monomers are copolymerized; one is a styrene or para-methylstyrene molar and the other is butadene, isoprene, chloroprene or acrylonitrile.

22. The process of claim 21, wherein the inflating agent is a hydrocarbyl onium salt.

3. The process of claim 22 wherein the hydrocarbyl onium salt has the formula A-M + R 1 R 2 R 3 R 4, or A-Py + R 4 where A- is an anion M is N, S or P; R1, R2, R3 and R4 independently meaning the same or different group of hydrogen, alkyl, aryl or allyl, and Py means a pridinium or a substituted alkyl pyridium group.

24. The process of claim 23, wherein the polymerization is conducted in the presence of an emulsifying agent at a temperature that is in the range of about 5 ° C to about 100 ° C for a sufficient time to form the latex.

25. The process of claim 24, including the addition of a coagulating agent to the latex to coagulate the solid nanocomposite and then remove the solid nanocomposite.