JPH0222778B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to adhesives for waterproof sheets used for roofing materials, underground waterproofing, etc. The material for synthetic polymer roofing is ethylene-propylene-dien terpolymer (hereinafter referred to as
EPT), butyl rubber, polyvinyl chloride, etc. are used, but among these, vulcanized rubber sheets whose main component is EPT are the most commonly used due to their excellent durability and strength. Conventionally, polychloroprene solvent-based adhesives have been used as adhesives for such waterproof sheets, but
It is necessary to apply adhesive to both the base and the sheet, which may complicate the installation process, but above all, the problem is that the working environment deteriorates due to evaporation of the organic solvent, which cannot be ignored. Its use is particularly restricted indoors and underground. From this point of view, the use of various water-based adhesives has been proposed, and although they do not degrade the working environment and have good workability, they are still unsatisfactory in various respects in terms of performance. For example, acrylic products are alkali resistant,
Low-temperature adhesion is insufficient, and synthetic rubber-based materials have shortcomings in not only low-temperature adhesion but also durability. Waterproof sheets mainly composed of EPT have extremely low polarity and are hydrophobic, making them difficult to adhere to.
There was a demand for a water-based adhesive that could withstand use as an EPT tarpaulin sheet. The present inventors focused on an aqueous ethylene-vinyl ester copolymer dispersion that has high adhesion even to low polarity and hydrophobic substances, and in JP-A-56-88478, an ethylene-vinyl ester copolymer dispersion with a specific composition was developed. It has been shown that a composition consisting of an aqueous polymer dispersion and an isocyanate compound has excellent properties. However, when the composition is applied on one side to either a base material or an adherend, when it is completely dried and laminated,
Adhesive strength tends to decrease, especially in low-temperature environments during winter, so it is necessary to coat both sides. In the case of water-based adhesives, if the base to which they are applied is not water-absorbent, drying is inevitably slower than with organic solvent-based adhesives, and workability is poor when applied on both sides. The present inventors solved this drawback and conducted research to find an adhesive for waterproof sheets for on-site construction.
EPT has a glass transition temperature within a specific range.
The present inventors have discovered that even when coated on one side, a waterproof sheet containing as a main component exhibits particularly excellent low-temperature adhesion properties, resulting in the present invention. That is, for laminating waterproof sheets whose main components are an aqueous dispersion having an ethylene content of 5 to 50% by weight, a vinyl ester content of 50 to 95% by weight, and a glass transition temperature of -5°C to -40°C. It is an adhesive. Furthermore, the composition contains polyvinyl alcohol as a protective colloid. The term waterproof sheet referred to here refers to a sheet used for sheet waterproofing methods on roofs, subways, underground structures, heat storage tanks, water tanks, etc., and generally includes unvulcanized and vulcanized sheets made of EPT, butyl rubber, and mixtures thereof. , polychloroprene sheets, chlorosulfonated polyethylene sheets, ethylene-vinyl acetate copolymer sheets, polyvinyl chloride sheets, etc. Also, there are waterproof sheets made of the above synthetic polymers as main raw materials and laminated with base fabrics and other materials. Also includes asphalt-based waterproof sheets whose base fabric is impregnated with asphalt. The ethylene content of the ethylene-vinyl ester copolymer that can be used in the present invention is 5 to 50% by weight. At 5% by weight or less, the glass transition temperature is -5°C.
If the amount is less than 50% by weight, the adhesion to EPT will decrease, and if it exceeds 50% by weight, the cohesive force will be extremely reduced and the high temperature adhesive strength will decrease. Also, the vinyl ester content is 50 to 95
% by weight. If it is less than 50% by weight, the cohesive force will decrease and the high temperature adhesive strength will decrease, and if it exceeds 95% by weight, the low temperature adhesive strength will decrease. Vinyl esters used in the present invention include vinyl esters of aliphatic carboxylic acids having 2 to 12 carbon atoms, such as vinyl acetate, vinyl propionate, vinyl laurate, vinyl tertiary carboxylates having an average of 10 carbon atoms (VeoVa10, Among them, vinyl acetate, vinyl propionate, VeoVa10, and mixtures thereof are particularly effective. Furthermore, as long as the above two components are within a specific range, it is also possible to use a component copolymerizable with these two components. Acrylic esters are particularly desirable, and butyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, etc. are suitable. Other copolymerizable unsaturated compounds include acrylic acid,
Unsaturated carboxylic acids such as methacrylic acid, maleic acid, fumaric acid, crotonic acid, itaconic acid, methacrylic acid esters, N-vinylpyrrolidone, acrylamide, 2-hydroxyethyl acrylate, N-methylolacrylamide, glycidyl methacrylate, chloride Examples include vinyl, diallyl phthalate, triallyl cyanurate, and ethylene glycol dimethacrylate. The aqueous dispersion used in the present invention is usually obtained by pressure polymerization in the presence of a surfactant or a protective colloid, but a protective colloid is preferable, and the protective colloid may be used alone or in combination with a surfactant. It is valid. Polyvinyl alcohol (hereinafter referred to as PVA) is the best protective colloid, with an average degree of polymerization of 100 to 4200 and a degree of saponification of 70.
In addition to using ~100 mol% of partially or completely saponified products, acrylonitrile,
Copolymerization of unsaturated carboxylic acids such as acrylamide, crotonic acid, acrylic acid, methacrylic acid, maleic acid, itaconic acid, and their alkyl esters with vinyl acetate, followed by saponification, and PVA.
So-called denatured products, such as those that react with sulfuric acid, phosphoric acid, formalin, urea, maleic anhydride, etc.
PVA or PVA derivatives can also be used. Protective colloids other than PVA include maleic anhydride-isobutylene copolymer, carboxylic acid-modified styrene copolymer, hydroxyethyl cellulose,
Hydroxypropyl cellulose etc. can be used.
As the surfactant, commercially available anionic surfactants, nonionic surfactants, and cationic surfactants are used. As the polymerization initiator, water-soluble inorganic peroxides or persulfates such as hydrogen peroxide and potassium persulfate, azo compounds, and the like are used. It is also possible to use redox initiators in combination with these and reducing agents.
In the polymerization method, the vinyl ester may be added all at once, in portions, or continuously. The glass transition temperature of the aqueous copolymer dispersion applied to the present invention is limited to -5°C to -40°C.
The value of the transition temperature varies depending on the measurement method, but here we will use torsional blade analysis (TBA,
This refers to the value at a frequency of 1Hz or less. Regarding TBA, see, for example, New Experimental Chemistry Course No. 19 edited by the Chemical Society of Japan.
Volume, page 904 (published by Maruzen in 1978). When the glass transition temperature is higher than -5°C, the adhesive strength at room temperature and at low temperature decreases, and when the glass transition temperature is lower than -40°C, the high temperature adhesive strength decreases, which is inappropriate. Especially -10℃~-35℃
A range of is preferred. A feature of the present invention is the use of a specific adhesive when bonding waterproof sheets containing non-polar EPT as a main component. In other words, general water-based adhesives
Many EPT materials have properties that allow them to be used as release agents, let alone adhesive properties, and even the well-known aqueous dispersion of ethylene-vinyl ester copolymer has low adhesive properties. However, an emulsion copolymer mainly composed of vinyl ester and ethylene with a glass transition temperature of -5℃ to -40℃ is called EPT.
The adhesion to is significantly increased, and especially the low temperature adhesion strength is improved. The adhesive has ethylene as its main component.
Unlike rubber-based products, oligomers are synthesized during polymerization, and tackifying substances are also automatically synthesized, resulting in significantly improved adhesion to waterproof sheets and other substances, and improved workability. will also be good. Furthermore, one of the characteristics of the performance of the present invention is that it is non-polluting, water-based, does not require a primer on the adherend, and can be bonded with one-sided coating, as well as having high adhesive strength, cold resistance, It also has excellent heat resistance and aging resistance. In addition, the adhesive composition used in the present invention may be mixed with an aqueous dispersion of other polymers as necessary, such as vinyl acetate polymers, alkyl acrylate copolymers, olefin polymers, etc. Examples include aqueous dispersions of vinyl chloride polymers, styrene-butadiene copolymers, and the like. Furthermore, the adhesive of the present invention may contain other commonly used additives such as thickeners, tackifiers, plasticizers, antifoaming agents, pigments, phenolic resins, melamine resins, urea resins, and epoxy compounds. A crosslinking agent such as the above may be mixed, but as in the case of mixing other aqueous polymer dispersions described above, the amount is limited to an amount that does not deteriorate the performance of the composition. Hereinafter, the present invention will be specifically explained with reference to Examples and Comparative Examples, but these examples are not intended to limit the present invention in any way. Note that "parts" and "%" in these examples are expressed on a weight basis unless otherwise specified. In addition, the adhesive strength was measured by the following method. Adhesion conditions (1); Flexible board (JIS-A-
5403, 4mm thick) using a roller to apply 300g of adhesive.
(wet) / m ² coating amount and open time.
30 minutes, 25mm (width) x 100mm (length) EPT sheet (manufactured by TS-S Toyo Tire & Rubber Co., Ltd.) was pressed once with a roller, and after curing for 3 days at 20°C, bonding of (1) to (4) A force measurement test was conducted. (1) Normal peel strength Measured using an autograph under conditions of a peel angle of 180°, a peel rate of 100 mm/min, and a measurement temperature of 20°C. (2) Water resistant peel strength After being immersed in tap water at 20°C for one week, the peel strength was measured in a wet state according to (1). (3) High temperature creep test Shear creep was measured at 70°C under a load of 200g. (Adhesive area: 25mm x 25mm) (4) Low-temperature adhesion Adhesive at 5℃ using the method described in adhesive condition (1),
After curing for 3 days at ℃, the 180° peel strength was measured at 5℃. Example 1 In an autoclave with a stirrer and a jacket, 60.3 parts of ion-exchanged water, 0.2 parts of sodium bicarbonate, 0.5 parts of potassium persulfate, PVA (degree of saponification 88 mol%,
Polymerization degree 500) 2.6 parts, polyoxyethylene nonyl phenyl ether (number of moles of ethylene oxide added =
30) 1.3 parts were added and dissolved uniformly, and the ethylene pressure was increased to 50 Kg/cm ² and adjusted to 30±1°C. 0.06 parts of sodium metabisulfite and 0.26 parts of ion-exchanged water
1/6 of this solution was added to the autoclave. At the same time, 52.5 parts of vinyl acetate was continuously added over 11 hours, and a solution of 1.3 parts of polyoxyethylene nonyl phenyl ether (number of moles of ethylene oxide added = 30) dissolved in 33.7 parts of ion-exchanged water was successively added. Polymerization started immediately upon addition of vinyl acetate. During the polymerization, the remainder of the sodium metabisulfite solution was added in five portions. Incidentally, during the polymerization, a small amount of sample was appropriately sampled and the vinyl acetate concentration in the system was determined by bromine titration method, and it was found to be 1% or less in all cases. Also, the ethylene pressure is 50Kg/
cm ² and temperature was kept constant at 30±1° C. until the end of the vinyl acetate addition. The resulting aqueous dispersion had good stability. The composition of the dispersion is shown in Table 1. Table 2 also shows the peel strength measured under the above conditions. As is clear from the table, the adhesive properties at low temperatures are good, and the normal and water resistance strength and high temperature creep properties are also excellent. Example 2 In the same autoclave as Example 1, the average degree of polymerization was
1700, 4.5 parts of PVA with saponification degree of 88 mol% was dissolved in 70 parts of ion-exchanged water, and ethylene was added under pressure of 35 kg/ ^cm2 .
At 60°C, 76 parts of a vinyl ester of a tertiary carboxylic acid having an average carbon number of 10 and 4 parts of vinyl acetate were continuously polymerized using a 1% aqueous solution of hydrogen peroxide and a 5% aqueous solution of Rongarit. The resulting aqueous dispersion had good stability. The composition of the dispersion is shown in Table 1. Further, the peel strength measured in the same manner as in Example 1 is shown in Table 2. Example 3 In the same autoclave as Example 1, the average degree of polymerization was
1700, 2 parts of PVA with a saponification degree of 88 mol% and 2 parts of a nonionic activator (Nonipol 400, manufactured by Sanyo Chemical Co., Ltd.) at 70%
of acrylic acid, 60 parts ^of vinyl acetate,
22 parts of 2-ethylhexyl acrylate was continuously polymerized using a 2% aqueous solution of ammonium persulfate. The composition of the obtained aqueous dispersion is shown in Table 1, and the results of measurement of adhesive performance are shown in Table 2. Example 4 Aqueous dispersions with different monomer compositions were obtained using the same polymerization method as in Example 3. Its composition is shown in Table 1. A composition was prepared by adding and mixing 3 parts of dibutyl phthalate to 100 parts of the dispersion, and the adhesive performance was evaluated. The results are shown in Table 2. Example 5 Aqueous dispersions with different monomer compositions were obtained using the same polymerization method as in Example 3. Its composition is shown in Table 1. The adhesive performance of the dispersion is shown in Table 2. Example 6 Polymerization was carried out under the same conditions except that 5 parts of a nonionic surfactant (Nonipol 200) was used in place of 5 parts of PVA in Example 2. The composition of the obtained aqueous dispersion was
Shown in the table. The adhesive performance of the dispersion is shown in Table 2. Example 7 In place of 5 parts of PVA in Example 2, 1 part of hydroxyethylcellulose and a nonionic activator (Nonipol) were used.
Polymerization was carried out under the same conditions except that 4 parts of 200) were used. The composition of the aqueous dispersion obtained is shown in Table 1.
The adhesive performance of the dispersion is shown in Table 2. Comparative Examples 1 to 4 Polymerization was carried out using the same polymerization method as in the examples, but with different monomer compositions. The composition of the aqueous dispersion obtained is shown in Table 1. Adhesion performance measured under the same conditions as Example 1 is shown in Table 2. As is clear from Table 2, the glass transition temperature is -
Those outside the range of 5℃ to -40℃, those with an ethylene content of 5% by weight or less, and those with a vinyl ester content outside of the range of 50 to 95% by weight are normal, water resistance, low-temperature peel strength, and high-temperature creep properties. It can be seen that one of these is low. Furthermore, the glass transition temperature is -5
Those with an ethylene content of 5 to 50% by weight and a vinyl ester content of 50 to 95% by weight at a temperature of ℃ to 40℃ have high normal water resistance, low-temperature peel strength, and high-temperature creep properties, but among them, PVA is a protective colloid. It is recognized that the aqueous dispersion containing PVA is superior to those using hydroxyethyl cellulose or nonionic activators other than PVA.

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Claims (1)

[Scope of Claims] 1 The main component is an aqueous dispersion having an ethylene content of 5 to 50% by weight, a vinyl ester content of 50 to 95% by weight, and a glass transition temperature of -5°C to -40°C. Adhesive for pasting waterproof sheets. 2 The main component is an aqueous dispersion with an ethylene content of 5 to 50% by weight, a vinyl ester content of 50 to 95% by weight, and a glass transition temperature of -5°C to -40°C containing polyvinyl alcohol as a protective colloid. Adhesive for laminating waterproof sheets.