摘要:
The compositions comprise: (a) at least 40 parts by weight, preferably at least 50 parts by weight, of at least one thio(meth)acrylate monomer, (b) at least one high Abbe number monomer, (c) at the most 20 parts by weight, preferably at the most 15 parts by weight and more preferably 10 parts by weight of an aromatic polyvinyl monomer, and (d) at least one polythiol, for 100 parts by weight of (a), (b), (c) and (d). Application for the manufacture of optical lenses.
摘要:
A radically polymerizable composition comprising: a first component A comprising at least an oligomer having at least two radically polymerizable functions and the homopolymer of which has a glass transition temperature (Tg) lower than 50° C., such a component being able to result through polymerization in a (co)polymer having a glass transition temperature (Tg) equal to or lower than 50° C., preferably equal to or lower than 0° C. and more preferably ranging from −50° C. to −10C, said oligomer accounting for more than 15%, preferably at least 20% of the total weight of the polymerizable monomers present in the composition; and a second component B comprising at least a (meth)acrylic monomer having at least one H link promoting group, such a (meth)acrylic monomer accounting for at least 15% of the total weight of the polymerizable monomers and oligomers present in the composition when such a monomer is a methacrylic monomer and at least 35% of the total weight of such polymerizable monomers and oligomers present in the composition when such a monomer is an acrylic monomer.
摘要:
The invention is a composition comprising: 40 to 95 parts by weight of one or several monomers (I) of formula (a) wherein: R1 and R2 represent H or CH; A represents a divalent radical of formula (b) or (c) wherein m1 and m2 represent each an integer ranging between 2 and 6; and 5 to 50 parts by weight of a monomer (II) comprising at least a urethane unit and at least two (meth)acrylate functions. The invention is useful for making optical and ophthalmic articles.
摘要:
The invention is a composition comprising: 40 to 95 parts by weight of one or several monomers (I) of formula (a) wherein: R1 and R2 represent H or CH; A represents a divalent radical of formula (b) or (c) wherein m1 and m2 represent each an integer ranging between 2 and 6; and 5 to 50 parts by weight of a monomer (II) comprising at least a urethane unit and at least two (meth)acrylate functions. The invention is useful for making optical and ophthalmic articles.
摘要:
A radically polymerizable composition comprising: a first component A comprising at least an oligomer having at least two radically polymerizable functions and the homopolymer of which has a glass transition temperature (Tg) lower than 50° C., such a component being able to result through polymerization in a (co)polymer having a glass transition temperature (Tg) equal to or lower than 50° C., preferably equal to or lower than 0° C. and more preferably ranging from −50° C. to −10 C., said oligomer accounting for more than 15%, preferably at least 20% of the total weight of the polymerizable monomers present in the composition; and a second component B comprising at least a (meth)acrylic monomer having at least one H link promoting group, such a (meth)acrylic monomer accounting for at least 15% of the total weight of the polymerizable monomers and oligomers present in the composition when such a monomer is a methacrylic monomer and at least 35% of the total weight of such polymerizable monomers and oligomers present in the composition when such a monomer is an acrylic monomer.
摘要:
The method comprises photopolymerizing by means of a light radiation of the visible and/or near UV field of a composition free of mineral particles, comprising at least one photopolymerizable monomer and at least one photoinitiator selected amongst suberone derivatives and mixtures of α-diketone and an organic peroxide. Application to the manufacture of ophthalmic lenses.
摘要:
One subject of the invention is a composition comprising from 5 to 65%, by weight relative to the total weight of the composition, of calcium silicate crystals; from 1 to 20%, by weight relative to the total weight of the composition, of calcium carbonate crystals; in addition from 0 to 50%, preferably from 1 to 40%, by weight relative to the total weight of the composition, of a compound of general formula mCaO.nSiO2.pH2O in which m and n, each independently, vary from 1 to 3 and p varies from 3 to 6; the ratio between the particle size d50 of the calcium silicate crystals and the particle size d50 of the calcium carbonate crystals being less than 10; another subject of the invention is a process for preparing said composition, and also the use of said composition in the dental field.
摘要:
The invention concerns a welding device and a welding method, in particular of tubular parts (c1, c2) such as abutting metal conduits to form pipeline metal pipes, which consists in effecting the penetrating pass from outside. The invention is characterized in that it consists in creating a single liquid weld metal under the simultaneous action of at least one laser beam (1) transmitted by optical fiber and at least one electric arc protected by gas generated from a consumable electrode (2a) constituting the filler material. The invention is mainly applicable to the construction of pipelines.
摘要:
The invention relates to a device for centring and clamping conduits which are preferably made from alloy steel and which are positioned end to end in order to be welded to form a pipeline. The invention comprises: means for centring and clamping two conduits that are to be welded, optional leak-tight partition means which define an inerting chamber at the mating surface, and inert gas distribution means for creating a protective atmosphere at the mating surface. The inventive device also comprises at least means for regulating the flow of inert gas and/or the supply pressure of said inert gas as a function of the concentration of O2 measured in the protective atmosphere and/or the pressure measured within said atmosphere, such as to maintain the O2 content of the atmosphere below a pre-determined alarm threshold value and/or the pressure of the atmosphere below a pre-determined threshold value.
摘要:
For displaying a selected zone of images belonging to a sequence of video images, each in the form of a matrix of pixels, on a display unit, a signal is generated by a fixed large-field camera having a definition that is greater than that of the display unit. A TV user or an operator at a control station selects a zone of format corresponding to that of the display unit in a field of view of the camera. The pixels of a modified image having the size and definition of the display unit are generated by interpolation from the pixels in the selected zone of the image supplied by the large-field camera. A device for implementing the method includes a module for warping the selected zone by operations of interpolation and resampling.