JP4641876B2 - Copolymer latex for nonwoven fabric binder - Google Patents

Description

  The present invention relates to a latex used as a binder for nonwoven fabrics, and more particularly to a latex for nonwoven fabric binders exhibiting excellent thermal tensile strength for asphalt-impregnated nonwoven fabrics used in the construction field.

Asphalt roofing materials in which non-woven fabric is impregnated with asphalt are widely used for waterproofing buildings, for example, for rooftop waterproofing of buildings. Since the asphalt-impregnated fabric is produced by impregnating a non-woven fabric with high-temperature asphalt, the non-woven fabric is required to have a high strength that can withstand processing at a high temperature. As a binder used for a nonwoven fabric for asphalt impregnation, a method of using a thermosetting amino resin such as melamine resin, urea resin, urea melamine resin and an aqueous emulsion or latex in combination is known (for example, Patent Document 1, Patent Document 2 and Patent Document 3). However, since binders mainly composed of thermosetting amino resins generate formalin during construction, reduction of formalin generation is desired. Methods such as reducing the amount of amino resin used or stopping the use of amino resin are conceivable, but in this case, the strength under high temperature becomes insufficient, so the aqueous emulsion or latex used in combination is improved. Is required.
As a method for preventing the occurrence of formalin, there has been proposed a method in which a latex having a high acid value and a glass transition temperature of 100 ° C. or higher is used as a binder without using an amino resin (Patent Document 4, Patent Document 5). Reference 6). However, a latex having a high acid value tends to have a high viscosity, and its workability is reduced during production and handling, so this improvement has been desired.

JP-A-6-136135 JP-A-9-170151 Japanese Patent Laid-Open No. 9-176947 Japanese Patent Laid-Open No. 6-263391 JP-A-6-263807 JP-A-7-258555

  An object of the present invention is to provide a latex that exhibits good workability during production and handling, and exhibits high strength at high temperatures when used as a binder for nonwoven fabrics.

In view of the above circumstances, the present inventors have found that a latex having a specific composition and a specific glass transition temperature has good workability and exhibits excellent performance as a nonwoven fabric binder. The invention has been completed.
That is, the present invention is as follows.
1. Obtained by emulsion polymerization of ethylenically unsaturated carboxylic acid monomer 1 to 20% by weight, vinyl cyanide monomer 3 to 50% by weight, and other copolymerizable monomer 96 to 30% by weight, A copolymer latex for a nonwoven fabric binder, characterized by having a glass transition temperature of 80 to 140 ° C.
2. 2. The copolymer latex as described in 1 above, wherein the ethylenically unsaturated carboxylic acid monomer is an ethylenically unsaturated monocarboxylic acid monomer.
3. 3. The copolymer latex as described in 1 or 2 above, wherein the glass transition temperature is from 90 to 128 ° C.
4). 0.5 g of the film obtained by drying the copolymer latex at 130 ° C. for 30 minutes is immersed in 30 g of toluene, shaken for 3 hours, filtered through a mesh of 300 mesh, and the dry weight of the undissolved matter remaining is wherein the toluene insoluble fraction was calculated by dividing the 0.5g of coating (gel content ratio) is 90% to 100%, the copolymer latex according to any one of the above 1 to 3 .
5. Wherein the vinyl cyanide monomer is 5 to 35 wt%, the copolymer latex according to any one of the above 1 to 4.
6). Nonwoven binder latex according to any one of the above 1 to 5, wherein the nonwoven fabric is for asphalt impregnation.

  The copolymer latex of the present invention is easy to handle and at the same time has the effect of exhibiting high strength at high temperatures when used as a binder for nonwoven fabrics.

The present invention will be specifically described below.
In the present invention, it is essential to use an ethylenically unsaturated carboxylic acid monomer. The ethylenically unsaturated carboxylic acid monomer is important for imparting the strength of the nonwoven fabric and the strength at high temperatures. The amount used is 1 to 20% by weight based on the weight of all monomers. The use of 1 % by weight or more is preferable from the viewpoint of adhesive strength and stability, and the use of 20 % by weight or less is preferable from the viewpoint of latex viscosity related to workability during handling of latex. Preferred examples of the ethylenically unsaturated carboxylic acid monomer include acrylic acid, methacrylic acid, itaconic acid, fumaric acid, maleic acid, crotonic acid, butenetricarboxylic acid, monoethyl maleate, monomethyl maleate, monoethyl itaconate, and itacone. An acid monomethyl etc. can be mentioned, These can be used individually or in combination of 2 or more types. From the viewpoint of hygroscopic dimensional stability of the nonwoven fabric, ethylenically unsaturated monocarboxylic acid monomers such as acrylic acid and methacrylic acid are preferred.

  The vinyl cyanide monomer in the present invention is necessary for imparting hardness, strength and heat resistance strength to the latex. The amount used is 2 to 50% by weight, preferably 3 to 40% by weight. From the viewpoint of heat resistance strength, 2% by weight or more is preferable, and from the viewpoint of stability during polymerization, 50% by weight or less is preferable. Specific examples of the vinyl cyanide monomer include acrylonitrile, methacrylonitrile, α-chloroacrylonitrile and the like, and these can be used alone or in combination of two or more.

In the present invention, another copolymerizable monomer is essential. Appropriate hardness can be set for the copolymer latex by appropriately selecting other copolymerizable monomers. Examples of other copolymerizable monomers include aromatic vinyl monomers such as styrene, α-methylstyrene, vinyltoluene, p-methylstyrene, 1,3-butadiene, isoprene, 2-chloro-1 Conjugated diene monomers such as 1,3-butadiene, alkyl acrylates such as methyl acrylate, ethyl acrylate, butyl acrylate and 2-ethylhexyl acrylate, alkyl methacrylates such as methyl methacrylate and butyl methacrylate Esters, hydroxyalkyl esters such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, aminoalkyl esters such as aminoethyl acrylate, dimethylaminoethyl acrylate, diethylaminoethyl acrylate, 2-vinylpyridine, 4-vinylpyridine Pyridines, glycidyl esters such as glycidyl acrylate, glycidyl methacrylate, acrylamide, methacrylamide, N-methylol acrylamide, N-methyl acrylamide, N-methyl methacrylamide, glycidyl methacrylamide, N, N-butoxymethyl acrylamide, etc. Amides, carboxylic acid vinyl esters such as vinyl acetate, and vinyl halides such as vinyl chloride. These may be used alone or in combination of two or more.
When a conjugated diene monomer is used as another copolymerizable monomer, the preferred amount is 20% by weight or less. The appropriate use of conjugated dienes is effective for improving the heat resistance, but in order to prevent the strength from being lowered at a high temperature accompanying the reduction in the glass transition temperature, the use of 20% by weight or less is preferable.

The copolymer latex in the present invention has a glass transition temperature of preferably 80 ° C. to 140 ° C., more preferably 90 ° C. to 140 ° C., from the viewpoint of strength development of the nonwoven fabric at a high temperature. The glass transition temperature of the copolymer can be set within a preferable range by appropriately adjusting the monomer composition to be used. Moreover, when setting the glass transition temperature exceeding 140 degreeC, it is usually necessary to use ethylenically unsaturated carboxylic acid exceeding 25 weight%, and the handleability of latex falls.
The glass transition temperature of the copolymer of the present invention can be measured by, for example, a differential scanning calorimeter or a dynamic viscoelasticity measuring device.

There is no restriction | limiting in particular about the method of emulsion polymerization for obtaining the copolymer latex of this invention, Well-known methods, such as superposing | polymerizing with a radical initiator in presence of surfactant in an aqueous medium, can be used.
There is no restriction | limiting in particular also about the emulsifier to use, A conventionally well-known anion, a cation, an amphoteric, and a nonionic surfactant can be used. Examples of preferred surfactants include anions such as aliphatic soaps, rosin acid soaps, alkyl sulfonates, dialkyl allyl sulfonates, alkyl sulfosuccinates, polyoxyethylene alkyl sulfates, polyoxyethylene alkyl allyl sulfates, etc. Nonionic surfactants such as a reactive surfactant, polyoxyethylene alkyl ether, polyoxyethylene alkyl allyl ether, and polyoxyethylene oxypropylene block copolymer are used, and these are used alone or in combination of two or more.

  The radical initiator initiates addition polymerization of the monomer by radical decomposition in the presence of heat or a reducing agent, and either an inorganic initiator or an organic initiator can be used. Preferred examples include peroxodisulfates, peroxides, azobis compounds, and the like. Specifically, potassium peroxodisulfate, sodium peroxodisulfate, ammonium peroxodisulfate, hydrogen peroxide, t-butyl hydroperoxide, benzoyl peroxide, 2,2 -Azobisbutyronitrile, cumene hydroperoxide, etc. In addition, POLYMER HANDBOOK (3rd edition), J. MoI. Brandrup and E.I. H. Examples include compounds described in Immergut, published by John Willy & Sons (1989). These can be used alone or in combination of two or more. In addition, a so-called redox polymerization method in which a reducing agent such as acidic sodium sulfite, ascorbic acid or a salt thereof, erythorbic acid or a salt thereof or Rongalite is used in combination with a polymerization initiator can also be used.

Although the polymerization temperature at the time of polymerizing the copolymer latex of the present invention is not particularly limited, it is usually 5 to 100 ° C, preferably 50 to 100 ° C, more preferably 70 to 95 ° C.
In the emulsion polymerization for obtaining the copolymer latex of the present invention, a known chain transfer agent usually used in radical polymerization can be used. Preferred examples of the chain transfer agent include α-methylstyrene dimer, n-butyl mercaptan, t-butyl mercaptan, n-octyl mercaptan, n-lauryl mercaptan, etc., which is one of dimers of nucleus-substituted α-methylstyrene. Examples include mercaptans, disulfides such as tetramethylthiudium disulfide and tetraethylthuradium disulfide, halogenated derivatives such as carbon tetrachloride and carbon tetrabromide, and 2-ethylhexyl thioglycolate. These may be used alone or in combination. Can be used in combination. Moreover, there is no restriction | limiting in particular in the addition method of a chain transfer agent, Well-known addition methods, such as collective addition, batch addition, and continuous addition, are used.

  In the emulsion polymerization for obtaining the copolymer latex of the present invention, a known method can be used as a method of adding the monomer mixture to the reactor, and any of batch addition, continuous addition, and divided addition may be used. . A method of continuously adding a monomer mixture having a constant composition to a reactor is common, but a method of adding several types of monomer mixtures having different compositions in multiple stages can also be effectively used. Examples of the method of adding the monomer mixture in multiple stages include a two-stage polymerization method and a three-stage polymerization method. In any case, ethylene is added to the monomer mixture to be added in the final stage. It is preferable to contain a polymerizable unsaturated carboxylic acid and a vinyl cyanide monomer.

  In the emulsion polymerization, various known polymerization regulators can be used as necessary. These are, for example, pH adjusters, chelating agents, etc. Preferred examples of pH adjusters include sodium hydroxide, potassium hydroxide, ammonium hydroxide, sodium hydrogen carbonate, disodium hydrogen phosphate, and the like. Preferable examples include sodium ethylenediaminetetraacetate.

  The solid content and particle size of the copolymer latex of the present invention are not particularly limited. Usually, the solid content is 30 to 60% by weight, and the particle size is 0.04 to 0.4 μm, preferably 0.05 to 0.2 μm. It is prepared in the range of It is also possible to use a known seed polymerization method for adjusting the particle size, such as an internal seed method in which a copolymer latex is polymerized in the same reaction system after preparing the seed, an external seed method using a separately prepared seed, etc. These methods can be appropriately selected and used.

Although there is no restriction | limiting in particular also about the gel content (toluene insoluble content) of the copolymer latex of this invention, Usually, 70-100%, Preferably it is 80-100%, More preferably, it is 90-100%.
Various additives may be added to the copolymer latex of the present invention as necessary. For example, a dispersant, an antifoaming agent, an anti-aging agent, a water resistant agent, a bactericidal agent, and the like can be added.

  When the copolymer latex of the present invention is used as a nonwoven fabric binder, the copolymer latex can be used by being attached to the nonwoven fabric alone, but can also be used with other materials. For example, a crosslinking agent, a water-soluble binder, other latex, a thickener, and the like. The crosslinking agent is not particularly limited, and amino resins such as melamine resin, urea resin, urea-melamine resin, epoxy resin, urethane resin (block isocyanate) and the like can be used. As the water-soluble binder, starch, polyvinyl alcohol, or the like can be used. Examples of other latexes include alkali-sensitive latexes and latexes other than the copolymer latex of the present invention. A well-known thing can be used for a thickener.

The copolymer latex of the present invention is used as an adhesive for a nonwoven fabric, but the method for adhering to the nonwoven fabric is not particularly limited, and for example, methods such as impregnation and coating can be used. The material of the nonwoven fabric in which the copolymer of the present invention can be used as an adhesive is not particularly limited. For example, synthetic fibers such as polyester fiber, polyamide fiber, and vinylon fiber, carbon fiber, glass fiber, silk, cotton, hemp For example, natural fibers can be used. Among these, a polyester fiber is suitable for the nonwoven fabric for asphalt roofing materials.
The copolymer latex of the present invention usually uses 15 to 30% by weight (solid content) with respect to the nonwoven fabric.

The present invention will be described based on examples.
[Example 1]
A pressure-resistant reaction vessel equipped with a stirrer and a temperature control jacket is charged with 70 parts by weight of ion-exchanged water, 0.50 parts by weight of seed latex having a particle size of 0.0215 μm, and 0.3 parts by weight of sodium dodecylbenzenesulfonate. The temperature was raised to 80 ° C. Subsequently, 100 parts by weight of a monomer mixture consisting of 80 parts by weight of styrene, 15 parts by weight of acrylonitrile and 5 parts by weight of methacrylic acid was added in 5 hours, 20 parts by weight of water, 1 part by weight of sodium peroxodisulfate, and 0.1% of sodium hydroxide. An initiator aqueous solution consisting of 2 parts by weight and 0.1 part by weight of sodium dodecylbenzenesulfonate was added at a constant flow rate for 5.5 hours. After the addition of the monomer mixture and the initiator aqueous solution was completed, the reaction was continued at 90 ° C. for 1.5 hours to obtain a copolymer latex having a polymerization conversion rate of 95% or more. The copolymer latex was adjusted to pH 7.0 with sodium hydroxide, and then unreacted monomers were removed by a steam stripping method. The pH was adjusted to 8.0 with aqueous ammonia to adjust the solid content to 50% by weight. The latex obtained as described above was measured for particle size, glass transition temperature, and toluene insoluble content by the following methods. The results are shown in Table 1.

(Particle size)
The particle size was determined with a light scattering particle size analyzer (Model 6000 manufactured by CNN Wood). (Glass-transition temperature)
The obtained copolymer latex was sufficiently dried at 130 ° C. to prepare a film, and this film was measured using a differential calorimeter (DSC-220C) manufactured by Seiko Electronics Co., Ltd. under a temperature rising rate of 15 ° C./min. did.
(Toluene insoluble matter)
The obtained latex is dried at 130 ° C. for 30 minutes to form a film. Next, about 0.5 g of a test sample for measurement is precisely weighed from the obtained film, immersed in 30 g of toluene, shaken for 3 hours, and then filtered through a 300 mesh stainless steel mesh. The undissolved matter remaining on the mesh at this time was dried, and the weight was divided by the sample weight to obtain a toluene insoluble fraction.

[Examples 2 to 4]
A copolymer latex was obtained in the same manner as in Example 1 except that the composition of the monomer mixture used was changed as shown in Table 1. The particle diameter, toluene insoluble matter, and glass transition temperature are shown in Table 1.
[Example 5]
As in Example 1, 70 parts by weight of ion-exchanged water, 0.50 parts by weight of seed latex having a particle size of 0.0215 μm, and 0.5 parts by weight of sodium dodecylbenzenesulfonate were charged in a pressure-resistant reaction vessel, and the internal temperature was 80 ° C. The temperature was raised to. Next, as the first stage, a monomer mixture consisting of 4 parts by weight of styrene, 8 parts by weight of butadiene and 2 parts by weight of acrylonitrile was added over 1 hour. Simultaneously with the addition of the monomer mixture, the addition of an aqueous initiator solution consisting of 20 parts by weight of water, 1 part by weight of sodium peroxodisulfate and 0.2 parts by weight of sodium hydroxide is started, and the addition of all monomers is completed. Until 6 hours. One hour after the addition of the first stage monomer is completed, the second stage is a monomer mixture comprising 56 parts by weight of styrene, 24 parts by weight of acrylonitrile, 2 parts by weight of acrylic acid and 4 parts by weight of methacrylic acid. Was added in 4 hours. After the addition of the second monomer mixture and the initiator aqueous solution was completed, the reaction was continued at 90 ° C. for 1.5 hours to obtain a copolymer latex having a polymerization conversion rate of 95% or more. The copolymer latex was adjusted to pH 7.0 with sodium hydroxide, and then unreacted monomers were removed by a steam stripping method. The pH was adjusted to 8.0 with aqueous ammonia to adjust the solid content to 50% by weight. The particle diameter, toluene insoluble matter, and glass transition temperature are shown in Table 2.

[Example 6]
In the same manner as in Example 1, 70 parts by weight of ion exchange water, 0.50 part by weight of seed latex having a particle size of 0.0215 μm, and 0.3 parts by weight of sodium dodecylbenzenesulfonate were charged in a pressure-resistant reaction vessel, and the internal temperature was 80 ° C. The temperature was raised to. Next, as a first stage, a monomer mixture composed of 6 parts by weight of styrene and 6 parts by weight of butadiene was added over 0.5 hours. Simultaneously with the addition of the monomer mixture, the addition of an aqueous initiator solution consisting of 20 parts by weight of water, 1 part by weight of sodium peroxodisulfate and 0.2 parts by weight of sodium hydroxide is started, and the addition of all monomers is completed. Until continuously added over 6.5 hours. One hour after the addition of the first stage monomer is completed, as the second stage, a monomer mixture comprising 25 parts by weight of styrene, 5 parts by weight of methyl methacrylate, and 8 parts by weight of acrylonitrile is added for 1.5 hours. Added over time. One hour after the completion of the second stage addition, as the third stage, a monomer mixture consisting of 35 parts by weight of styrene, 10 parts by weight of acrylonitrile and 5 parts by weight of methacrylic acid was added over 2.5 hours. After the addition of the third stage monomer mixture and the initiator aqueous solution was completed, the reaction was continued at 90 ° C. for 1.5 hours to obtain a polymerization conversion rate of 95
% Or more of copolymer latex was obtained. The copolymer latex was adjusted to pH 7.0 with sodium hydroxide, and then unreacted monomers were removed by a steam stripping method. The pH was adjusted to 8.0 with aqueous ammonia to adjust the solid content to 50% by weight. The particle diameter, toluene insoluble matter, and glass transition temperature are shown in Table 2.

[Comparative Examples 1 and 2]
A copolymer latex of Comparative Examples 1 and 2 was obtained in the same manner as in Example 1 except that the composition of the monomer mixture used was changed as shown in Table 1. The particle diameter, toluene insoluble matter, and glass transition temperature are shown in Table 1.
[Comparative Examples 3 and 4]
The copolymer latexes of Comparative Examples 3 and 4 were polymerized in the same manner as in Example 1 except that the composition of the monomer mixture used was changed as shown in Table 1. The latex of Comparative Example 3 was remarkably thickened by pH adjustment and lost fluidity, so no further evaluation was performed. In addition, the latex of Comparative Example 4 had a large amount of aggregates as a result of the polymerization, and normal latex could not be isolated, so evaluation was not performed.

The obtained latexes of Examples 1 to 6 and Comparative Examples 1 and 2 were evaluated for performance as a nonwoven fabric binder as follows.
(Preparation of evaluation sample)
After adjusting the solid content of the obtained copolymer latex to 30%, a polyester fiber non-woven fabric 20 cm × 20 cm having a basis weight of 100 g / m ² is immersed in the copolymer latex and becomes 180 g / m ² with a mangle. The mixture was squeezed out and left in a dryer set at 105 ° C. for 10 minutes. Subsequently, it was left for 10 minutes in a dryer set at 150 ° C. to obtain a target evaluation sample. The solid content adhesion amount of the copolymer latex was 24 g / m ² . The obtained binder-processed nonwoven fabric was cut to prepare test pieces having a length of 15 cm and a width of 5 cm.

(Tensile test at room temperature)
A tensile test was performed at 23 ° C. using a tensile tester. Evaluation was performed at a distance between chucks of 10 cm and a tensile speed of 500 mm / min. The evaluation results are shown in Table 3.
(Tensile test after high-temperature treatment) The specimen was treated at 180 ° C for 1 minute and then evaluated in the same manner as the tensile test at room temperature. The evaluation results are shown in Table 3.
As is apparent from Table 3, the latexes of the examples showed good results both in the tensile test at normal temperature and in the tensile test after high temperature treatment.

  The copolymer latex of the present invention is excellent in strength at high temperatures and is suitable as a binder for nonwoven fabrics used for asphalt impregnation.

Claims (6)

  Obtained by emulsion polymerization of ethylenically unsaturated carboxylic acid monomer 1 to 20% by weight, vinyl cyanide monomer 3 to 50% by weight, and other copolymerizable monomer 96 to 30% by weight, A copolymer latex for a nonwoven fabric binder, characterized by having a glass transition temperature of 80 to 140 ° C.   The copolymer latex according to claim 1, wherein the ethylenically unsaturated carboxylic acid monomer is an ethylenically unsaturated monocarboxylic acid monomer.   The copolymer latex according to claim 1 or 2, wherein the glass transition temperature is 90 to 128 ° C. 0.5 g of the film obtained by drying the copolymer latex at 130 ° C. for 30 minutes is immersed in 30 g of toluene and shaken for 3 hours, and then filtered through a 300-mesh mesh to determine the dry weight of the undissolved material remaining. The copolymer according to any one of claims 1 to 3, wherein a toluene insoluble fraction (gel content ratio) calculated by dividing by 0.5 g of the film is 90 to 100%. latex.   Copolymer latex according to any one of claims 1 to 4, characterized in that the vinyl cyanide monomer is 5 to 35% by weight.   The latex for nonwoven fabric binder according to any one of claims 1 to 5, wherein the nonwoven fabric is for asphalt impregnation.