JPH023811B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a rational water-crosslinking method that prevents early crosslinking of a laminate in which at least one layer is made of a water-crosslinkable olefin polymer and provides high heat seal strength. Regarding crosslinking of water-crosslinkable olefin polymers,
Generally, an olefin polymer having a hydrolyzable organic silane bonded to its main chain or side chain and a masterbatch containing a high concentration of silanol condensation catalyst are mixed in appropriate proportions, and after molding, A method of water-crosslinking by placing in water or an atmosphere containing moisture has been adopted. The water-crosslinked molded product thus obtained has excellent heat resistance and mechanical strength, and is therefore suitable for use as a wire covering material, a packaging material film, and the like. However, according to this method, early crosslinking tends to occur during the molding process, which causes hard eyes and spots, and sometimes extremely reduces spreadability, making it extremely difficult to form into sheets or films. There are many cases where the product value is inferior. In particular, in the case of processing methods such as extrusion lamination that require high-temperature molding close to 300°C, the influence of early crosslinking is particularly significant, making it difficult to form a film. Conventionally, in order to solve this kind of problem, olefin polymers with hydrolyzable organic silane bonded to the main chain or side chain have been proposed in JP-A-54-11154, JP-A-52-103463, JP-A-52-9073, etc. A method has been proposed in which only the combined product is molded and then a silanol condensation catalyst is applied or impregnated onto the surface of the molded product. According to this method, the condensation catalyst tends to remain on the surface of the molded product, and in some cases, problems such as reduced heat seal strength and printing defects may occur during secondary processing such as heat sealing and printing. It is. On the other hand, in the packaging field, packaging materials have recently come to be required to have special functions such as gas barrier properties, heat resistance during heat sterilization, and appearance in addition to mechanical strength, and a single base material cannot meet these required performances. As a result, there is an increasing demand for the use of multiple base materials such as composite materials and laminated materials. Among these, especially in the case of laminated materials using water-crosslinkable olefin polymers as mentioned above, the drawbacks mentioned above, such as early crosslinking and reduction in heat seal strength, are problems that must be solved. Ta. The present invention provides a solution to these problems, namely, a layer of a water-crosslinkable olefin polymer (layer A) and a layer of a base material other than the water-crosslinkable olefin polymer (layer C). , a water-crosslinkable olefin polymer characterized in that an adhesive layer (B layer) in which a silanol condensation catalyst is blended with a solvent or adhesive is laminated between these A and C layers, and the laminate is crosslinked with moisture. This is a method for manufacturing laminates. According to the method of the present invention, there are the following advantages. (1) Since the silanol condensation catalyst is not kneaded with the water-crosslinkable olefin polymer or comes into contact with the water-crosslinkable olefin polymer for a long time before the lamination step, early crosslinking can be avoided. (2) Since the silanol condensation catalyst does not adhere to the non-laminated surface of the water-crosslinkable olefin polymer layer, the heat seal strength on that surface does not decrease after water-crosslinking. (3) By laminating an adhesive containing a silanol condensation catalyst between the water-crosslinkable olefin polymer layer and other base material layers, a laminate with high adhesive strength between each laminated layer can be obtained. (4) These laminates can be easily obtained by the (co)extrusion lamination method. Next, the present invention will be specifically explained. <Layer A> The water-crosslinkable olefin polymer of layer A, which constitutes at least one layer of the water-crosslinked laminate obtained by the method of the present invention, is composed of a water-crosslinkable olefin polymer having a hydrolyzable organic silane bonded to the main chain or side chain. "olefin polymer" or an olefin polymer blended with this polymer, and there are two types of this polymer: (i) and (ii) below. (i) Olefin polymers with hydrolyzable organic silanes bonded to side chains. An olefin polymer and an ethylenically unsaturated organic silane having a hydrolyzable organic group (hereinafter simply referred to as unsaturated silane) are mixed in the presence of a free radical generator at a temperature higher than the decomposition temperature of the radical generator. A typical example is one obtained by reaction. This reaction product will have a structure having branches formed by graft copolymerization of the unsaturated silane onto a trunk made of the olefin polymer. (a) Olefin polymer The olefin polymer to be used as the backbone for graft copolymerization with unsaturated silanes is an α-olefin homopolymer, different types of α-olefins, or other types containing a predominant amount of α-olefin units. It is a copolymer with a monomer. This copolymer includes all types of copolymers such as random type, block type and graft type. Specifically, for example, there are the following groups (i) to (e). These can be used together within each group or between each group. (a) α-olefin homopolymer. (b) Copolymers of different α-olefins. (c) Copolymers of α-olefin and derivatives such as unsaturated organic acids, their anhydrides, their salts, and esters. (d) Copolymers of α-olefin and other monomers such as styrene, methylstyrene, vinyl chloride, and vinylidene chloride. (e) Halides such as those of the above groups (a) to (d). Typical α-olefin compounds include ethylene, propylene, butene-1, pentene-1, hexene-1, and 4-methylpentene-1. Further, as derivatives of unsaturated organic acids, their anhydrides, their salts, esters, etc., vinyl acetate, vinyl propionate, acrylic acid,
methacrylic acid, itaconic acid, maleic acid, etc.
or its anhydride, or these and C ₁ ~
Examples include esters with monohydric alcohols of about _C5 , ammonium salts, lower amine salts, alkali metal salts, and alkaline earth metal salts. (b) Ethylenically unsaturated organic silane The unsaturated silane grafted onto the olefin polymer backbone is preferably one represented by the following formula. RSiR′nY ₃ −n (where R represents an ethylenically unsaturated hydrocarbyl group or hydrocarbyloxy group, R′ represents an aliphatic saturated hydrocarbyl group, Y represents a hydrolyzable organic group,
n represents 0, 1 or 2. When there are multiple Y's, they do not have to be the same. ) (c) Graft copolymerization The graft copolymerization of the above olefin polymer and unsaturated silane is described, for example, in Japanese Patent Publication No. 48-1711.
Any suitable method described in can be selected and carried out. (ii) Olefin polymers with a hydrolyzable organosilane bonded to the main chain. This polymer is a copolymer of the unsaturated silane described above and the monomer constituting the olefin polymer. Specific examples include the following groups (a) to (d), but please refer to item (i) above for details of each monomer mentioned. (a) Copolymer of α-olefin and unsaturated silane (random copolymer, block copolymer) (b) α-olefin, unsaturated silane, unsaturated organic acid, its anhydride or its salt, ester copolymers with derivatives such as (c) Copolymers of α-olefin, unsaturated silane, and other monomers such as styrene, methylstyrene, vinyl chloride, and vinylidene chloride. (d) Halides such as those of the above groups (a) to (c). The method for producing this water-crosslinkable olefin polymer can be basically the same as the method for producing ordinary olefin polymers (for example, polyethylene and polypropylene), and for example, the method disclosed in U.S. Patent No.
The method described in No. 3392156 can also be used. The unsaturated silane content of the water-crosslinkable olefin polymer thus obtained is 0.01 to 10% by weight for the type (i), including the formulation blended with the olefin polymer as described above. %, preferably 0.05
-2% by weight, and 0.001-5% by weight of the type (ii), preferably 0.05-2% by weight. If these ranges are not met, the gel fraction required to obtain the desired heat resistance cannot be obtained, and problems such as edge breakage during hot sealing are likely to occur. On the other hand, if it exceeds the range, scorch is likely to occur during processing, and the heat sealability and tensile elongation of the obtained base material are reduced. <Layer B> The silanol condensation catalyst compound of layer B, which constitutes the laminate before crosslinking of the water-crosslinked laminate obtained by the method of the present invention together with the above-mentioned layer A and layer C described below, is a silanol condensation catalyst compound in a solvent or adhesive. Contains a catalyst. The present invention targets silanol condensation catalysts that can be used as catalysts that promote dehydration condensation between silanols of silicone. Such silanol condensation catalysts generally include carboxylic acid metal salt compounds such as tin, zinc, iron, lead, cobalt, organic bases, inorganic acids, and organic acids. Examples of these include dibutyltin dilaurate, dibutyltin diacetate, dibutyltin dioctoate, stannous acetate, stannous caprylate, lead naphthenate, zinc caprylate, cobalt naphthenate, ethylamine, hexylamine, These include pyridine, sulfuric acid, hydrochloric acid, toluenesulfonic acid, acetic acid, stearic acid, and maleic acid. As the solvent, which is another component of this formulation, a single substance capable of dissolving the above-mentioned silanol condensation catalyst or a mixture of substances can be used. Furthermore, even if the silanol condensation catalyst does not dissolve or is difficult to dissolve, it can be given the same functionality as a soluble one by using a dispersion aid such as a surfactant. These are also included in the solvent referred to here. Examples of these solvents include, for example, methanol, ethanol,
Alcohols such as butanol; hexane, heptane, 3-methylpentane, benzene, toluene,
All commonly used solvents such as aliphatic and aromatic hydrocarbons such as xylene; ketones such as acetone and methyl ethyl ketone; ethers; esters; nitriles; paraffin; and water emulsion can be used. In addition, as the adhesive used as a component of this compound, almost any adhesive substance can be used as long as it has adhesive properties, but among them, anchor coats, which are often used for bonding laminates, can be used. Adhesives called AC agents, olefin polymers graft-modified with unsaturated organic acids or their anhydrides, glycidyl compounds, etc.
An ionomer made of a copolymer of α-olefin and an unsaturated organic acid and a metal ion contained therein is preferred in terms of workability and adhesiveness. Specific examples of these include emulsions such as polyvinyl acetate and polyethyl acrylate, various ethylene-propylene, butadiene, or styrene-butadiene latexes, water-soluble adhesives such as polyethyleneimine, urethane adhesives, and titanates. Examples include adhesives such as maleic anhydride-modified polypropylene, maleic anhydride-modified polyethylene, and ethylene-acrylic acid ionomers. In particular, layers A and C, which are water-crosslinkable olefin polymers,
In terms of adhesion to the layer, urethane-based and titanate-based adhesives are excellent. Of course, other organic polymers having adhesive properties can be used as the adhesive mentioned here, but it is also possible to use adhesives such as those described above mixed with a solvent. The content of silanol condensation catalyst in this formulation is not particularly limited, but ranges from 0.5 to 10
% by weight is a relatively suitable range. If it is less than this range, it will take a long time to crosslink the water-crosslinkable polyolefins to be laminated, and if it exceeds this range, it may adversely affect the adhesive strength at the interface of the laminate. <C layer> In principle, the C layer, which is the other base material constituting the water-crosslinked laminate obtained by the method of the present invention, may be any layer other than the above-mentioned A layers and B layers. However, in reality, it is limited by required performance, workability, economic efficiency, etc. Therefore, generally, the olefin polymer used for the water-crosslinkable olefin polymer of layer A;
Polyamide, polystyrene, polyethylene terephthalate, acrylonitrile-butadiene-styrene copolymer (ABS resin), polyester, polyacrylonitrile, polymethyl methacrylate,
Non-olefinic polymer resins such as polycarbonate and cellophane; Rubbers such as ethylene-propylene (mono-nonconjugated diene) copolymer rubber, styrene-butadiene copolymer rubber, and organic silicone rubber; Compatible kneaded products of these; Metal foils of aluminum, zinc, tin, etc.; paper, etc., but also include those with various modifiers added to them. <Lamination method> In the method of the present invention, the layers A, B, and C may be laminated at the same time, or any two layers may be laminated first, and then the other layer may be laminated in addition thereto. However, from the point of view of preventing early crosslinking of the water-crosslinkable olefin polymer of layer A, it is preferable to laminate three layers at the same time or layer B on layer C, and then add layer B to layer C. A preferred method is to laminate the A layer. The method of laminating the B layer on the C layer is that if the B layer is a compound containing a silanol condensation catalyst in a solvent, it is coated with a roll coater to form a layer, or it is a compound in which a silanol condensation catalyst is blended in an adhesive. In the case of a product, a lamination method using an extrusion lamination method is preferred. As for the method of laminating layer A on the laminate of layer B and layer C, or the method of laminating three layers at the same time, the following various methods are preferable. Wet lamination Dry lamination Hot melt lamination Extrusion lamination Co-extrusion lamination The laminated adhesive surfaces of layers A and C may be subjected to treatment to improve adhesiveness, such as discharge treatment. The various thicknesses of the layers laminated by these methods are not particularly limited, but generally, when the thickness of layer A is 100, layer B is a coating layer with almost no thickness to 100 or less, and layer C is a coating layer with a thickness of 100 or less. 5 to 1000 is appropriate. <Water-crosslinking method> Methods for water-crosslinking the laminate made here include immersing it in water or hot water, exposing it to a steam atmosphere, or packaging it in water-containing materials. However, in principle, any method may be used as long as the laminate comes into contact with moisture; for example, it may be left in the atmosphere. The achieved gel fraction is controlled by the amount of silane compound contained in the water-crosslinkable olefin polymer. Examples and comparative examples will be shown below to more specifically explain the effects of the present invention. Example 1 One surface of a polyester film with a thickness of 12 μm was coated with 6% by weight of Titabond 104, an anchor coating agent (AC agent) manufactured by Nippon Soda, and 0.6% by weight of a hardening agent and T-curing agent manufactured by Nippon Soda. A solution prepared by dissolving 10 parts by weight of dibutyltin dilaurate, which is a silanol condensation catalyst, in 1000 parts by weight of the blended ethyl acetate solution was uniformly applied using a roll coater, and immediately after drying at 90°C, the coated surface was coated with resin at 300°C. Melt flow rate (MFR) at temperature
12gr/10min, water-crosslinkable polyethylene with 0.5% by weight vinyltrimethoxysilane attached to the backbone was extrusion laminated to a thickness of 20μ. The moldability and appearance of the extruded film at this time were as good as those of the general-purpose low-density polyethylene laminated grade "LM31" manufactured by Mitsubishi Yuka Co., Ltd. This laminated film is heated at 40℃ and relative humidity 60%.
The samples were aged for 3 days in a constant temperature and humidity chamber. The adhesive strength between the polyester film and the water-crosslinkable polyethylene was non-peelable, and the gel fraction of the water-crosslinkable polyethylene layer was 65% by weight. Comparative Example 1 To 100 parts by weight of the water-crosslinkable polyethylene used in Example 1, 2 parts by weight of polyethylene "Yukalon NH50" manufactured by Mitsubishi Yuka Co., Ltd. containing 1% by weight of a silanol condensation catalyst as a masterbatch was dry blended, When extruded at a resin temperature of 300℃,
Early crosslinking progressed rapidly, and the extrudate did not form a uniform film, making extrusion lamination impossible. Next, when the resin temperature was lowered to 265°C and the extrusion molding was carried out, the extrudate became a nearly uniform film shape, so the ethyl acetate solution containing the AC agent and curing agent used in Example 1 was used. Coated thickness (without added silanol condensation catalyst)
Laminated onto 12μ polyester film. At this time, the extrusion lamination moldability was insufficient, and the extruded film produced more fiber eyes (FE) than the general-purpose low-density polyethylene "LM31", which was inferior in terms of commercial value. It was hot. This laminated film was aged for 3 days in a constant temperature and humidity chamber at 40° C. and 60% relative humidity. The adhesive strength between the polyester film and the water-crosslinked polyethylene was almost zero. Comparative Example 2 In Example 1, a similar laminated film was molded using an ethyl acetate solution containing an AC agent and a curing agent without adding a silanol condensation catalyst. This laminated film was passed through a solution of 10% by weight dibutyltin dilaurate in methyl ethyl ketone using a method similar to that disclosed in JP-A-52-9073, and then heated at 40°C and at a relative humidity of 60%. It was aged for 3 days in a constant temperature and humidity chamber. Although the adhesive strength between the polyester and the water-crosslinkable polyethylene in this laminate was sufficient, the film surface became sticky and a blocking phenomenon of the film was observed. This film was heat sealed at 200° C., 1 Kg/cm ² G, and for 1 second. The heat seal strength at this time was 2.2 kg/2 cm. On the other hand,
The laminated film of Example 1 heat-sealed under similar conditions had a heat-sealing strength of 3.3 kg/2 cm. Example 2 Using a three-layer co-extrusion facility consisting of an extruder with a diameter of 50 mm for the innermost layer and a diameter of 40 mm for the middle and outer layers, an MFR of 2.7 gr/10 minutes and a density of 0.925 gr/cm ³ were achieved in the innermost layer. Water-crosslinkable polyethylene with a gel fraction of 60% by weight and 2% by weight of vinyltrimethoxysilane grafted onto the side chains; the intermediate layer is adhesive polyethylene "Modec L-100F" manufactured by Mitsubishi Yuka Co., Ltd. and a silanol condensation catalyst dibutyltin dilaurate. The composition in which 3% by weight was dispersed was extruded using Mitsubishi Kasei's polyamide "1020CA-2" as the outer layer at a die tip temperature of 240°C to a total thickness of 60μ (innermost layer 20μ, middle layer 20μ,
A three-layer laminated inflation film with an outer layer of 20μ) was obtained. At the time of this molding, patent application No. 54-36838 was applied.
A steam atmosphere was created inside the inflation tube using the method described above, and molding was performed to allow moisture to adhere to the inner surface of the inflation tube. After this film was left in an oven at 60°C for one day, the gel fraction of the water-crosslinkable polyethylene layer was measured to be 60% by weight, and a film with a very good product appearance was obtained. Comparative Example 3 Using the apparatus of Example 2, the outer layer was made of the same polyamide as used in Example 2, and the middle layer was made of "Modic L".
-100F'', 5 weight parts of a silanol condensation catalyst masterbatch containing 95 parts by weight of the same water-crosslinkable polyethylene used in Example 2 and 1 weight% silanol condensation catalyst mixed with polyethylene ``Yukalon NH50'' manufactured by Mitsubishi Yuka Co., Ltd. for the innermost layer. The dry blend with the following parts was molded under the same conditions as in Example 2 to obtain a three-layer laminated inflation tube. After this film was left in an oven at 60°C for one day, the gel fraction of the water-crosslinkable polyethylene layer was 58% by weight. Incidentally, the water-crosslinkable polyethylene portion of this three-layer film had many fine fissures, and its commercial value was low.

[Claims]

1. A tube is loosely inserted vertically into a processing tank where the processing liquid can be refluxed and inert gas can be injected, and then the processing liquid is automatically taken in and out of the processing tank to raise and lower the liquid level and raise and lower the tube. A method for treating a medical tube, which comprises drying the tube by injecting an inert gas into a treatment tank in which the treated tube is housed after its inner and outer surfaces have been treated over its entire length.