Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F255/00—Macromolecular compounds obtained by polymerising monomers on to polymers of hydrocarbons as defined in group C08F10/00
  • C08F255/02—Macromolecular compounds obtained by polymerising monomers on to polymers of hydrocarbons as defined in group C08F10/00 on to polymers of olefins having two or three carbon atoms
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
  • B29C48/022—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the choice of material
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
  • B29C48/25—Component parts, details or accessories; Auxiliary operations
  • B29C48/92—Measuring, controlling or regulating
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F255/00—Macromolecular compounds obtained by polymerising monomers on to polymers of hydrocarbons as defined in group C08F10/00
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C2948/00—Indexing scheme relating to extrusion moulding
  • B29C2948/92—Measuring, controlling or regulating
  • B29C2948/92504—Controlled parameter
  • B29C2948/92609—Dimensions
  • B29C2948/92657—Volume or quantity
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C2948/00—Indexing scheme relating to extrusion moulding
  • B29C2948/92—Measuring, controlling or regulating
  • B29C2948/92504—Controlled parameter
  • B29C2948/92714—Degree of crosslinking, solidification, crystallinity or homogeneity
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C2948/00—Indexing scheme relating to extrusion moulding
  • B29C2948/92—Measuring, controlling or regulating
  • B29C2948/92819—Location or phase of control
  • B29C2948/92828—Raw material handling or dosing, e.g. active hopper or feeding device
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
  • B29C48/03—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the shape of the extruded material at extrusion
  • B29C48/06—Rod-shaped
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
  • B29C48/03—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the shape of the extruded material at extrusion
  • B29C48/09—Articles with cross-sections having partially or fully enclosed cavities, e.g. pipes or channels
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
  • B29K2301/00—Use of unspecified macromolecular compounds as reinforcement
  • B29K2301/10—Thermosetting resins

Definitions

• the invention relates to a process for producing a polymer product cross-linked by silane. It is known in the art that the properties of polymers, such as polyethylene and other polyolefins, can be modified by cross-linking. Polyethylene, for example, can be cross-linked using a peroxide initiator, a hydrolyzing silane compound and a condensation catalyst as described in US patents 3 646 155 and 4 117 195.
• Said process can be carried out by injecting a polyethylene, a peroxide, for example dicumyl peroxide, a silane compound, for example vinyl trimethoxy silane or vinyl triethoxy silane and a condensation catalyst, for example dibutyltin dilaurate into an extruder and by extruding, whereby a grafted product is obtained which is then processed in condensation conditions in the presence of water or aqueous steam for providing a cross-linked product.
• a peroxide for example dicumyl peroxide
• a silane compound for example vinyl trimethoxy silane or vinyl triethoxy silane
• a condensation catalyst for example dibutyltin dilaurate
• What mainly affects the cross-linking degree is the amounts of components fed into the extruder, the specific cross-linking conditions, the pressures and temperatures, and also the size of the extruder.
• the amounts of peroxide initiator, silane compound and condensation catalyst affect the cross-linking degree.
• the insulation properties can be affected by varying said amounts.
• the cross-linking degree has been manually determined in a laboratory by analyzing a sample taken from the cross-linked product obtained after the condensa- tion treatment. If the cross-linking degree has been unsatisfactory, the feed of the starting components has been readjusted in order to obtain the desired product.
• the problem is that undesired changes may frequently occur in the reaction conditions of the continuous process that disadvanta- geously affect the properties of the final product. Since the manual analysis is slow, a lot of poor quality products may be formed that naturally cause economical losses. For example, when cables and conductors are insulated, and the production line is long, the amount of rejected items can be very high, if the feed of the components is adjusted on the basis of the manually obtained analyzing results of the final product.
• the present invention relates to a process for producing a polymer product cross-linked by silane where a polymer, a silane, an initiator and a cross-linking catalyst and possible additives are fed into an extruder and extruded, whereafter the grafted material obtained is cross-linked using water and the catalyst for obtaining a cross-linked polymer product.
• the process is characterized in that the grafting degree of the grafted material is determined using an on line method and based upon the result obtained the amounts of the components to be fed into the extruder are continuously adjusted in order to obtain the desired grafting degree.
• the grafting degree is appropriately determined by measuring the contents of free and grafted silane in the grafted product.
• the free silane content is determined by measuring the area of the absorption peak at 810 cm "1 in the IR spectrum of the silane, whereas the grafted silane content is similarly measured from absorption peak 1080 cm 1 .
• grafted polyethylene silane mixtures are used, whose silane content as well as the silane content of a corresponding grafted material are defined by means of an NMR spectroscope, for example.
• the amount of peroxide has to be appropriate, originally about 0.1 % by weight, in order that the silane, the amount of which is about 0.8 to 2 % by weight, is efficiently grafted so that no direct cross-linking disturbing the grafting takes place without silane. In a well-grafted material the amount of remaining peroxide is very low, hardly measurable.
• the peroxide content can be controlled by measuring the area of the absorption peak at 1155 cm “1 by means of an IR spectroscope. The calibration is carried out in the same way as in the case of silane. As the grafting degree is determined using a continuous on line measuring method, the results are rapidly obtained, and the feed of starting components can also be rapidly affected if needed. On the basis of the measuring results the feed of starting components can automatically also be adjusted using a computer as described below.
• the adjustment can, for example, be based on an algorithm that may be of a fuzzy logic type. Next the examples of the measurements and adjustments are shown when a silane/peroxide mixture is fed and when silane and peroxide are separately fed.
• Example 1 Feeding a ready-mixed silane/peroxide mixture
• Typical polymers to be cross-linked, whose grafting degree can be adjusted by the process of the invention, are polyolefins, preferably polyethylene and polypropylene.
• the cross-linked product is preferably a cable or conductor insulation, a plastic pipe or profile.
• the cross-linking catalyst is preferably a dibutyltin dilaurate.
• a hydrolyzing silane compound, preferably vinyl trimethoxy silane, is used as the grafting agent and the initiator is typically a peroxide compound, preferably dicumyl peroxide.
• Conventional additives include antioxidants and colourants.
• the cross- linking degree can further be determined during the run, for example by utilizing a thermomechanical analyzer that measures the elastic properties of the material.
• the thin measuring head is pressed by a constant load against the cross-linked material and the size of the elastic deflection depending on the cross-linking degree of the polymer, the temperature and the load put upon the measuring head is registered.
• the registered deflection values are compared with a calibration curve measured with a corresponding material at the same temperature, thus providing the cross-linking degree corresponding to the deflection.
• thermomechanical analyzer may be composed of two wheels placed at the opposite sides of a cable or another polymer product to be run and pressed against the same, one wheel being pressed by means of a known force, and the deflection caused by the wheel in the product is measured, and of a registration apparatus for registering deflections and also the temperature of the material.
• the apparatus example shows only one way of measuring the elastic properties of the product on the line during the run, but the example is not intended to restrict the scope of the patent.

Landscapes

• Chemical & Material Sciences (AREA)
• Polymers & Plastics (AREA)
• Health & Medical Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Medicinal Chemistry (AREA)
• Organic Chemistry (AREA)
• Mechanical Engineering (AREA)
• Engineering & Computer Science (AREA)
• Graft Or Block Polymers (AREA)
• Processes Of Treating Macromolecular Substances (AREA)
• Processes Specially Adapted For Manufacturing Cables (AREA)
• Manufacture Of Macromolecular Shaped Articles (AREA)
• Extrusion Moulding Of Plastics Or The Like (AREA)

Applications Claiming Priority (3)

Publications (1)

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• 1999
  • 1999-03-18 FI FI990613A patent/FI105198B/fi not_active IP Right Cessation
• 2000
  • 2000-03-17 KR KR1020017011628A patent/KR20010114221A/ko not_active Application Discontinuation
  • 2000-03-17 CN CNB008052298A patent/CN1137166C/zh not_active Expired - Fee Related
  • 2000-03-17 JP JP2000605651A patent/JP2002539304A/ja active Pending
  • 2000-03-17 AU AU34367/00A patent/AU3436700A/en not_active Abandoned
  • 2000-03-17 WO PCT/FI2000/000221 patent/WO2000055225A1/en not_active Application Discontinuation
  • 2000-03-17 EP EP00912707A patent/EP1200495A1/en not_active Withdrawn

Non-Patent Citations (1)

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