GB1566038A - Laminated products containing a plasticised sulphur composition - Google Patents

Description

(54) LAMINATED PRODUCTS CONTAINING A PLASTICIZED SULFUR COMPOSITION (71) We, CHEVRON RESEARCH COMPANY, a corporation duly organized under the laws of the State of Delaware, United States of America, and having offices at 575 Market Street, San Francisco, California, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The present invention relates to laminated products incorporating plasticized sulfur, prepared by specified heating and cooling. The plasticized sulfur is a good adhesive and can be used as a bonding agent in, for example, making pipe out of layers of paper.

Plasticized sulfur has been disclosed in various references, for example by J. I.

Jin in "Chemistry of Plasticized Sulfur", Petroleum Division, A.C.S. Symposium, Vol. 19, No. 2, March 1974, pp. 234-241, and by C. Kinney Hancock in "Plasticized Sulfur Compositions for Traffic Marking", Industrial and Engineering Chemistry, Vol. 46, No 11, November 1954, pp. 2431-2435. Exemplary patents disclosing plasticized sulfur (and heating temperatures at which the plasticized sulfur is formed) include U.S. Patent 2,169,814, "Bonding and Coating Product" (heating temperatures of 15106"C); U.S. Patent 3,306,000, "Construction Method" (heating temperatures of 135-1750C); U.S. Patent 3,316,115, "Marking Composition" (heating temperature of 1600C); U.S.Patent 3,371,072, "Sulphur Resins" (heating temperatures of 100--200"C, preferably 110160 C); U.S.

Patent 3,384,609, "Plasticized Sulphur" (heating temperatures of 120--250"C, preferably 140-160 C); U.S. Patent 3,434,852, "Plasticized Sulfur Compositions" (heating temperatures of 50--250"C, preferably 100--200"C, and exemplary temperatures of 130--170"C); U.S. Patent 3,447,941, "Sprayable Sulfur Road Marking Compositions" (heating temperature of 150"C); U.S. Patent 3,453,125, "Plasticized Sulfur Compositions" (heating temperatures of -20.-2500C and exemplary temperatures of 138--170"C); U.S. Patent 3,459,717, "Sulfur-Based Plastic Composition" (heating temperatures of 115--200"C, preferably 140- 170 C); U.S.Patent 3,465,064, "Adhesive Plasticized Sulphur Containing an Olefine Polymer" (heating temperatures of 100-200 C, preferably 140- 150 C); U.S. Patent 3,560,451, "Plastic and Nonflammable Sulfur Composition" (heating temperatures of l20-l800C, preferably 140-160 C); U.S.

Patent 3,640,965. "Thermoplastic Sulfur Containing Polymers"; U.S. Patent 3,647,525, "Plasticized Sulfur Compositions" (heating temperatures of 50--250"C and exemplary temperature of about 155"C); U.S. Patent 3,676,166, "Plasticized Sulfur Compositions" (heating temperatures of 75400" F, preferably 250350 F and exemplary temperature of 300"F); U.S. Patent 3,734,753, "Plasticized Sulfur Compositions" (heating temperatures of 1 l8-2500C, preferably 1500C); and U.S.

Patent 3,787,276, "Corrugated Cardboard Containing Sulphur Foam" (heating temperature of 1100C); also Serial No. 286,627, now U.S. Patent 3,823,019, "Mine Wall Coating" (heating temperatures of 24-320"F, preferably 275-320 F), which application has been offered for license by the U.S. Bureau of Mines, discloses plasticized sulfur compositions.

As can be seen from the examples in the above patents, temperatures which are suggested by the patents for heating or carrying out a reaction to obtain the plasticized sulfur compositions are generally about 150"C (302"F). U.S. Patent 3,734,753 thus discloses at Col. 2, line 50, with respect to preparation of plasticized sulfur compositions: "It is preferable to maintain the temperature of the reaction mixture at about 1500C since pure sulfur becomes viscous at 1600C and higher temperatures raise the cost of processing." "Elemental Sulfur," edited by B.Meyer, Interscience Publ. (1965) discloses in Chapter 5 the sharp increase in sulfur viscosity at about 1590C. Chapter 8 of "Elemental Sulfur" discloses as follows: "Both the arsenic-modified and phosphorus-modified systems are dark red in color, have objectionable odors, and tend to recrystallize when exposed to light and air. Arsenic-sulfur system are more stable and such materials have been fabricated into a variety of products including lenses, prisms, tubes, and fibers.

"Polymeric sulfides and polysulfides are more promising modifiers for elemental sulfur, tending to stabilize the material in a plasticized form. These materials, on heating with sulfur to temperatures above its polymerization point (159"C), form viscous liquids which on cooling show distinct polymeric properties.

These compositions recrystallize elemental sulfur only after comparatively long periods of time, depending upon the concentration of polysulfide polymers used.

Compositions having as little as 10-15% of the polymer [ethylene tetrasulfide], after heating to 16e1750C, remain in a polymeric form several days before completely recrystallizing. Larger quantities of the ethylene tetrapolysulfide give pliable materials which remain largely unchanged in properties for several weeks, following which hardening occurs on the recrystallization of sulfur.

"Mixtures of ethylene polysulfides with sulfur have been studied extensively by Tobolsky and co-workers [J. of Polymer Sci. A2, 1987 (1964)]. Both linear and crosslinked systems have been produced. Each produces extensive supercooling of sulfur. Systems containing as much as 40% supercooled liquid sulfur have remained free of crystallization for over three years." In one of its applications, the present invention is concerned with a method for preparing laminated conduit or pipe. Exemplary prior art patents in this area include U.S. Patents 1,943,501, "Manufacture of Paper Tubes", for example shotgun shells; 3,055,278, "Reinforced Plastic Pipe"; 3,323,962, "Reinforced Resinous Tubular Laminates" for use in electrical insulating, etc; and 3,767,500, "Method of Laminating Long Strips of Various Materials".

According to the present invention, there is provided a method of producing a laminated product, which comprises (1) heating a platicised sulfur composition to a temperature in the range of from 1600C to 220"C; (2) cooling the heated plasticised sulfur composition; and (3) contacting a sheet material with the plasticised sulfur composition before, during or after the cooling step to produce a laminate. The method of the invention will generally comprise the further step of shaping the laminate. The sheet material used in the laminate is preferably paper or a paperlike material.

Preferably the hot plasticized sulfur in the laminate is cooled to a temperature below 155"C, for example a temperature of 150"C or lower. The tacky plasticized sulfur tends to stay tacky or adhesive-like for a longer length of time than does plasticized sulfur not subjected to the heating treatment in accordance with the present invention. Also, we have found that the plasticized sulfur in the laminate can generally be cooled to a temperature below its normal melting point to thereby obtain a supercooled plasticized sulfur which exhibits good adhesive properties.

Further, the plasticized sulfur, especially when plasticized with dicyclopentadiene, exhibits lower viscosity at high temperatures of 160220 C (the preferred range in the heating step being 170--2100C) than does pure sulfur at these high temperatures. This makes the plasticized sulfur relatively easy to work with in obtaining the tacky, cooled plasticized sulfur composition. The relatively reduced viscosity (compared to pure sulfur) is not as reduced at the high temperature when fillers such as talc are included in the composition.

The plasticized sulfur advantageously comprises sulfur reacted with an organic compound effective to plasticize the sulfur as is described in more detail hereinbelow. Preferably the plasticized sulfur is brought to a temperature between 1700 and 210"C before the cooling step, and still more preferably between 175"C and 210 C before the cooling step. Tackiness is enhanced by the inclusion of materials such as talc, mica and other finely divided or fibrous mineral fillers.

Tackiness for the composition having only an organic plasticizer usually does not develop unless the composition is impregnated or coated on a substrate such as paper or a paper-like material.

The plasticized sulfur compositions exhibit adhesive properties after they have been cooled somewhat, and are preferably used while in the supercooled liquid state, as opposed to after the compositions arrive at steady-state equilibrium and become solidified masses. Using the compositions after cooling, and preferably while supercooled liquid, facilitates relatively easy handling at or about room temperature, e.g. at le-500C, more usually 12-380C.

The plasticized sulfur composition also has the advantageous properties of being usually water-tight and chemical-resistant, particularly acid-resistant.

The composition obtained via the heating procedure of the present invention is particularly advantageous in that upon cooling it retains liquid characteristics longer so that upon thermal contraction due to cooling relatively few stresses are created, compared to what would be the case with normal solidification at the normal melting point and then cooling of the solid. In such normal cooling, stresses are apt to make cracks or warp the material. Therefore, one advantageous application of the present composition is in areas where minimal cracking and the like is important.

The plasticized sulfur composition is particularly valuable in forming paper products, in packaging, in forming containers such as barrels or boxes, and in forming construction panels and construction members. The composition is useful as a reinforcement medium with paper and wood products as well as being an adhesive and thus can advantageously be used in laminating layers of paper or paper-like material into a container wherein the adhesive composition is used to hold the paper or paper-like material together. The composition can be used as an adhesive simply to hold the layers together, but also can be used at the seams or edges of a container to hold the seams or various sides of the container together.

The invention also provides laminated products produced by the method of the invention. In a preferred embodiment, a laminated conduit or pipe is provided.

Suitable types of paper or paper-like material which may be used for forming conduit or pipe and also for forming other laminated articles such as containers using the method of the present invention include Kraft paper, newspaper, tissue, felt, cardboard, bagasse, cotton, cloth as natural or synthetic, polypropylene felts, and fibers in woven, random or spun form.

The plasticized sulphur composition can be advantageously used to form structures due to the adhesive character of the composition. Structural members can be bonded together using the composition and also structural members such as beams or poles can be built up using the composition as a rigidifying and bonding agent. Advantageously beams or poles and the like can be made from fibers, synthetic or natural, or wood products with the plasticized sulfur composition serving to hold the components of the member together and rigidifying the structural member.

Among other factors, the present invention is based on our finding that plasticized sulfur prepared as described herein has especially advantageous tackiness after cooling and also tends to retain tackiness even below its normal solidification temperature, and hence has advantageous properties as an adhesive or bonding agent. Heating to a lower temperature-for example 150"C (3020 F), typically employed in the prior art of plasticized sulfur-does not achieve the highly workable plasticized sulfur composition as in the present invention especially the tacky, liquid composition obtained directly after the cooling in accordance with the present invention.

Although the plasticized sulfur composition can be used after both the heating to a temperature above 1600C, and the cooling to a temperature below 160"C, the hot plasticized sulfur can also be used while it is at a high molten temperature, which may or may not be above the 160"C temperature. The hot, molten, plasticized sulfur in any case must be heated to a temperature above 160"C, and preferably above 1700C, in accordance with the present invention so that the composition can subsequently be obtained either in situ or as a transitional composition after application of the hot plasticized sulfur to paper or other substrate.Thus, paper or other substrate can be impregnated with hot plasticized sulfur above the melting point and then cooled-for example supercooled to below the melting point to obtain a surface still tacky or adhesive, for instance like Scotch tape. The thus-obtained surfaces are then preferably bonded together or to another object before solidification of the cooled plasticized sulfur occurs. Time limits while the material remains tacky or nonsolidified will, of course, exist and will be a function of the time and amount of heating as well as of the amount of type of plasticizer used.

The term "liquid" plasticized sulfur is used herein to embrace nonsolidified and nonrigidified plasticized sulfur. For example, plasticized sulfur which is still tacky or which has not solidified sufficiently to rigidify paper impregnated with the plasticized sulfur is considered to be "liquid" plasticized sulfur.

Plasticized sulfur compositions contemplated by the present invention preferably contain principally sulfur. Preferably the plasticized sulfur contains more than 50 weight percent sulfur and more preferably 70--90 weight percent sulfur or more.

"Plasticized sulfur" as the term is used herein usually has a slightly lower melting point than elemental sulfur. Furthermore, plasticized sulfur requires a longer time to crystallize; i.e., the rate of crystallization of plasticized sulfur is slower than that of elemental sulfur. One useful wav to measure the rate of crystallization is as follows: the test material (0.040 g) is melting on a microscope slide at 1300C and is then covered with a square microscope slide cover slip. The slide is transferred to a hot plate and is kept at a temperature of 78+2"C, as measured on the glass slide using a surface pyrometer. One corner of the melt is seeded with a crystal of test material. The time required for complete crystallization is measured.Plasticized sulfur, then, is sulfur containing an additive which increases the crystallization time within experimental error, i.e., the average crystallization time of the plasticized sulfur is greater than the average crystallization time of the elemental sulfur feedstock. For the present application, plasticizers are those substances which, when added to molten elemental sulfur, cause an increase in crystallization time in reference to the elemental sulfur itself.

In one set of experiments, elemental sulfur required 0.44 minute to crystallize under the above conditions, whereas sulfur containing 3.8% of a phenol-sulfur adduct (as described in British Patent Specification No. 1,422,379) required 2.9 minutes. Sulfur containing 6.6% and 9.9% of the same phenol-sulfur adduct required 5.7 and 22 minutes, respectively.

Inorganic plasticizers include iron, arsenic and phosphorus sulfides, but the particularly preferred plasticizers are organic compounds which can react with sulfur to give sulfur-containing materials, such as styrene, alphamethystyrene; dicyclopentadiene, vinyl cyclohexene, the aromatic compound-sulfur adducts of U.K. Specification No. 1,422,379 as well as the aromatic compounds used to produce these adducts, aromatic or aliphatic liquid polysulfides (e.g., those sold under the trade names of Tiokol LP-3 or LP-321), and the viscosity-control agents described in U.S. Patents 3,674,525, 3,453,125 and 3,676,166. The preferred aromatic plasticizing compounds are styrene and the phenol-sulfur adduct of U.K.

Patent Specification No. 1,422,379. The preferred aliphatic compound is dicyclopentadiene.

One preferred plasticized sulfur substance contains dicyclopentadiene, sulfur, glass fiber and talc. It has also been found that asbestos can advantageously be used instead of glass fiber in the above plasticized sulfur substance.

The elemental sulfur may be either crystalline or amorphous, and may contain small amounts of impurities such as those normally found in commercial grades of sulfur. Optimum proportions of sulfur, as well as of the other components of the composition, may vary considerably. However, proportions of sulfur of 73% to 97%, by weight, are generally satisfactory.

Dicyclopentadiene is readily available commercially, generally at a purity of about 96% or greater. Preferably it is used in the abbve preferred plasticized sulfur composition in an amount of 1 to 7% by weight.

The glass fiber of the preferred plasticized sulfur composition is preferably employed in the form of milled fibers, with the fibers generally ranging from 1/32" to 1/4" in length, preferably with an average length of about 1/16". These fibers, which generally consist of high-silica glass, are readily available commercially, often coated with starch binder. The type of glass is, however, not critical, as long as it provides the resulting composition with adequate shear strength, preferably a shear strength of 400 to 800 psi. The glass fiber preferably constitutes 1 to 5%, by weight of the composition of the invention.

The talc used in the preferred dicyclopentadiene-sulfur-glass fiber-talc composition preferably is a foliated type, or a compact variety such as steatite.

Impure varieties such as soapstone can also be used. This ingredient is preferably used in an amount of 1 to 15% by weight of the composition, and serves the dual function of providing thixotropy to the mixture and of dispersing the glass fiber throughout the composition, thereby preventing agglomeration of the fibers.

EXAMPLES Example I A plasticized sulfur was prepared by mixing about 2 weight percent organic plasticizer, namely dicyclopentadiene, with molten sulfur.

Eight-mil-thick Kraft paper coupons were treated with the molten plasticized sulfur at various temperatures. The paper coupons were dipped into the molten plasticized sulfur and then hung up to dry by exposure to room-temperature air.

The time was recorded with the first dry spot appeared, when the coupons were 50% dry, and when they were 95 dry. The term "dry" is used here to denote becoming solidified and nontacky rather than in the normal sense of drying by evaporation of a solvent.

The impregnated coupons contained about 85 weight percent plasticized sulfur. In practising the present invention, the paper-like material can be impregnated or coated with 5 to 90 weight percent plasticized sulfur (based on the paper and plasticized sulfur) bit preferably 10 to 50 weight percent is used. Thus the 85 weight percent is somewhat higher than normal.

When the plasticized sulfur had been heated at 1500C for 1 or 2 hours, it solidified and become nontacky very rapidly when impregnated onto the paper.

See Table I below.

TABLE I Paper Impregnation at Constant Temperature Plasticized Sulfur Heating Time Drying time, minutes at 150"C, hours Start 50% dry 95%dry Fast Fast 0.1 3 2 6 15 4 3 8 17 8 3 10 17 When the plasticized sulfur was heated to higher temperatures than 150"C, it took longer to dry or solidify. See Table II.

TABLE II Paper Impregnation at Variable Temperatures Elapsed time for Plasticized sulfur heating, Drying time, minutes Heating steps hours Start 50% dry 95% dry lhouratl600C 1 3 5 9 RaiseTtol700C 1-1/2 5 13 22 Take out of oven & BR< coolto 1350C 1-5/8 3 8 22 RaiseTtol500C 1-3/4 4 16 30 RaiseTto 1950C 2-1/4 9 23 47 Thus, comparing the data of Table I to Table II, it is seen that if plasticized sulfur is heated at 160--1700C or higher, then a plasticized sulfur which gives delayed solidification is formed faster (compared to when lower heating temperatures are used); and it also gives more delayed solidification or more prolonged retention of adhesiveness or tackiness.

Example 2 A plasticized sulfur composition containing sulfur, dicyclopentadiene, talc and glas fibers was prepared as follows: A stainless-steel beaker equipped with a stirrer is charged with 90 parts of sulfur which is then heated until molten. While maintaining the temperature of the stirred, molten sulfur at 1380C, 1.8 parts of dicyclopentadiene is added. After 10 minutes of reaction time, 6.4 parts of talc (Mistron Vapor talc) is added ("Mistron" is a registered Trade Mark). Then, after the talc is well mixed in, 1.18 parts of 0.25" milled glass fiber (Owens-Corning #630 glass fiber) is added. Stirring at 138"C is then continued for an additional 1/2 hour. Upon cooling to room temperature, this material forms a hard, opaque mass which can be broken into smaller pieces for ease of handling.

The plasticized sulfur composition obtained as above-described was used in the construction of a container, in particular the construction of a box which had a substantial degree of water-tightness retention ability. Thus, about 2 grams of plasticized sulfur was placed on a hot plate and heated to a temperature of about 185"C. The molten material was spread out with a spatula to a thickness of about 1/64". Then a 4"x4" piece of Kraft bag paper was placed on the molten, highly viscous plasticized sulfur and was gently pressed down with the spatula over its surface. Then, while still in place on the hot plate, a second 2 grams of plasticized sulfur was placed on top of this Kraft paper and was allowed to melt. This material was likewise spread over the entire upper surface of the paper.Then a second 4"x4" piece of Kraft bag paper was placed over the first and pressed down with a spatula. Finally, a third 2-gram portion of plasticized sulfur was placed on the top of the 2 plies of paper and allowed to melt and spread.

While still hot (about 185"C), the plasticized sulfur-impregnated 2-ply paper laminate was removed from the hot plate and cooled to room temperature in about 10 seconds. The laminate was plastic and was sticky on both surfaces. It was formed into a box by folding the sides up and lapping the corners. The seams were closed by squeezing the edges together. This box held water without leakage for more than 24 hours.

Example 3 The plasticized sulfur of Example 2 was utilized to form a laminate from 12 plies of newspaper, about 38x3", by the same technique as described in Example 2.

After the 12-ply laminate was removed from the hot plate and rapidly cooled to 20"C, it was rolled into a tube which was sealed by pressing the edges together with about a 1/2 overlap. After about 1/2 hour, the tube lost is plasticity and set to a rigid tubular structure. The tube was unaffected by immersion in water.

WHAT WE CLAIM IS: 1. A method of producing a laminated product, which comprises (1) heating a plasticized sulfur composition to a temperature in the range of from 160 C to 2200C; (2) cooling the heated plasticized sulfur composition; and (3) contacting a sheet material with the plasticized sulfur composition before, during or after the cooling step to produce a laminate.

2. A method according to Claim 1, which further comprises the step of shaping the laminate.

3. A method according to Claim 1 or 2, wherein the heated plasticized sulfur composition is cooled to a temperature below 155"C.

4. A method according to Claim 4, wherein the cooling step is effected so that the plasticized sulfur composition passes into the supercooled liquid state.

5. A method according to Claim 1, 2, 3 or 4, wherein the sheet material is paper or a paper-like material.

6. A method according to any preceding claim, wherein the plasticised sulfur composition is heated to a temperature in the range of 175"C to 2100C.

7. A method according to any preceding claim, wherein the plasticized sulfur composition comprises a finely divided or fibrous mineral filler.

8. A method according to Claim 7, wherein the finely divided filler is mica or talc.

9. A method according to Claim 7, wherein the filler is glass fibre.

10. A method according to Claim 9, wherein the glass fibre constitutes from 1 to 5% by weight of the plasticized sulfur composition.

11. A method according to any preceding claim, wherein the plasticized sulfur composition comprises at least 70% sulfur by weight.

12. A method according to Claim 11, wherein the plasticized sulfur composition contains from 73 to 97% by weight sulfur.

13. A method according to any preceding claim, wherein the plasticized sulfur composition comprises one or more of styrene, alpha-methylstyrene, dicyclopentadiene, vinyl cyclohexene, aromatic or aliphatic liquid polysulfides, and phenol-sulfur adducts.

14. A method according to Claim 13, wherein the plasticized sulfur composition comprises from 1 to 7% by weight dicyclopentadiene.

15. A method according to Claims 10 and 14, wherein the plasticized sulfur composition further comprises from 1 to 15% by weight talc.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (19)

**WARNING** start of CLMS field may overlap end of DESC **. material forms a hard, opaque mass which can be broken into smaller pieces for ease of handling. The plasticized sulfur composition obtained as above-described was used in the construction of a container, in particular the construction of a box which had a substantial degree of water-tightness retention ability. Thus, about 2 grams of plasticized sulfur was placed on a hot plate and heated to a temperature of about 185"C. The molten material was spread out with a spatula to a thickness of about 1/64". Then a 4"x4" piece of Kraft bag paper was placed on the molten, highly viscous plasticized sulfur and was gently pressed down with the spatula over its surface. Then, while still in place on the hot plate, a second 2 grams of plasticized sulfur was placed on top of this Kraft paper and was allowed to melt. This material was likewise spread over the entire upper surface of the paper.Then a second 4"x4" piece of Kraft bag paper was placed over the first and pressed down with a spatula. Finally, a third 2-gram portion of plasticized sulfur was placed on the top of the 2 plies of paper and allowed to melt and spread. While still hot (about 185"C), the plasticized sulfur-impregnated 2-ply paper laminate was removed from the hot plate and cooled to room temperature in about 10 seconds. The laminate was plastic and was sticky on both surfaces. It was formed into a box by folding the sides up and lapping the corners. The seams were closed by squeezing the edges together. This box held water without leakage for more than 24 hours. Example 3 The plasticized sulfur of Example 2 was utilized to form a laminate from 12 plies of newspaper, about 38x3", by the same technique as described in Example 2. After the 12-ply laminate was removed from the hot plate and rapidly cooled to 20"C, it was rolled into a tube which was sealed by pressing the edges together with about a 1/2 overlap. After about 1/2 hour, the tube lost is plasticity and set to a rigid tubular structure. The tube was unaffected by immersion in water. WHAT WE CLAIM IS:

1. A method of producing a laminated product, which comprises (1) heating a plasticized sulfur composition to a temperature in the range of from 160 C to 2200C; (2) cooling the heated plasticized sulfur composition; and (3) contacting a sheet material with the plasticized sulfur composition before, during or after the cooling step to produce a laminate.

2. A method according to Claim 1, which further comprises the step of shaping the laminate.

3. A method according to Claim 1 or 2, wherein the heated plasticized sulfur composition is cooled to a temperature below 155"C.

4. A method according to Claim 4, wherein the cooling step is effected so that the plasticized sulfur composition passes into the supercooled liquid state.

5. A method according to Claim 1, 2, 3 or 4, wherein the sheet material is paper or a paper-like material.

6. A method according to any preceding claim, wherein the plasticised sulfur composition is heated to a temperature in the range of 175"C to 2100C.

7. A method according to any preceding claim, wherein the plasticized sulfur composition comprises a finely divided or fibrous mineral filler.

8. A method according to Claim 7, wherein the finely divided filler is mica or talc.

9. A method according to Claim 7, wherein the filler is glass fibre.

10. A method according to Claim 9, wherein the glass fibre constitutes from 1 to 5% by weight of the plasticized sulfur composition.

11. A method according to any preceding claim, wherein the plasticized sulfur composition comprises at least 70% sulfur by weight.

12. A method according to Claim 11, wherein the plasticized sulfur composition contains from 73 to 97% by weight sulfur.

13. A method according to any preceding claim, wherein the plasticized sulfur composition comprises one or more of styrene, alpha-methylstyrene, dicyclopentadiene, vinyl cyclohexene, aromatic or aliphatic liquid polysulfides, and phenol-sulfur adducts.

14. A method according to Claim 13, wherein the plasticized sulfur composition comprises from 1 to 7% by weight dicyclopentadiene.

15. A method according to Claims 10 and 14, wherein the plasticized sulfur composition further comprises from 1 to 15% by weight talc.

16. A method according to Claim 15, wherein the talc is steatite or a foliated

talc.

17. A laminated product produced by a method as claimed in any preceding claim.

18. A laminated product as claimed in Claim 17, wherein the product is a laminated conduit or pipe.

19. A laminated product substantially as described in the foregoing Example 2 or 3.