JPH0160578B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to nonwoven fabrics comprised of interwoven webs of adhesively bonded fibers. More specifically, the present invention relates to a flexible nonwoven fabric obtained using a new adhesive, which does not generate formaldehyde, and has excellent durability such as washability and dry cleaning resistance. Nonwovens are products that have a self-supporting, smooth structure, generally consisting of fibers that may or may not be bonded together by adhesives.
Fibers used for this purpose include, for example, natural fibers, vegetable fibers and animal fibers, modified natural fibers, recycled fibers such as rayon fibers, asbestos fibers, inorganic fibers such as glass cotton and slub cotton, synthetic fibers or their like. Nonwoven fabrics made from these mixtures are used in a wide variety of applications, including clothing, industrial materials, and sanitary materials. Nonwoven fabrics that do not use adhesives are used for sanitary materials or some industrial materials, but in general, the strength, dimensional stability, drapability, flexibility, etc. of the web are Various adhesives are used during or after the nonwoven fabric manufacturing process to improve physical properties such as wet strength, wet friction resistance, and heat resistance. As the adhesive, a water-soluble resin or polymer emulsion is usually used. Such water-soluble resins include urea/formaldehyde,
These include melamine/formalde resin forming condensates, water-soluble polyester resins, and polymer emulsions such as acrylonitrile-butadiene rubber latex and styrene-butadiene rubber.
Synthetic resin emulsions such as latex, chloroprene latex, polyvinyl chloride emulsion, polyacrylate emulsion, polyvinyl acetate emulsion, and polyurethane emulsion, natural rubber latex, and the like are used. Generally speaking, in order to further expand the uses of nonwoven fabrics, it is desirable to make soft nonwoven fabrics as long as possible. For this reason, adhesives with excellent flexibility and strength are strongly desired in the market. Of course, it is preferable from a sanitary standpoint that there is no eluted formaldehyde. However, in general, the softer the water-soluble resin or polymer emulsion mentioned above, the lower the strength and durability of the resin such as solvent resistance, and when it is made into a nonwoven fabric, it becomes sticky, which is the most undesirable. If an attempt is made to increase the strength, solvent resistance, and other durability of the resin, the resin becomes hard and brittle, and the resulting nonwoven fabric also tends to become hard. As described above, research using organic polymers as adhesives has limitations, and therefore research is being conducted on using adhesives made from blends of inorganic and organic polymers such as water glass and colloidal silica. When such inorganic polymers are blended, even if the resin is softened, it becomes less sticky and a soft, non-stick non-woven fabric can be made. The bond with the polymer is weak, the long-term durability of the nonwoven fabric is insufficient, and the physical properties tend to deteriorate. For this reason, conventionally, it has been extremely difficult to improve nonwoven fabric properties such as strength, durability such as solvent resistance, and heat resistance due to the properties of the adhesive. It was hot. Under these circumstances, the present inventors conducted intensive research to create a nonwoven fabric that is soft, non-binding, and has excellent strength and durability, and as a result, the present invention was achieved. Therefore, the present invention provides a nonwoven fabric bonded with an adhesive, in which the adhesive is (a) at least one monomer selected from α,β-monoethylenically unsaturated carboxylic acid alkyl ester and alkenylbenzene (hereinafter referred to as (b) Monomer containing a polymerizable unsaturated double bond and alkoxysilane in the molecule (hereinafter referred to as silane monomer) 0.1 to 10.0 parts by weight (in terms of solid content) (referred to as main monomer) Parts by weight (in terms of solid content) (c) Obtained by emulsion polymerization of 1.0 to 200 parts by weight (in terms of solid content) of colloidal silica in an aqueous system in the presence of an anionic surfactant and/or a nonionic surfactant. To provide a nonwoven fabric using an aqueous resin dispersion. The aqueous resin dispersion used as the adhesive used to make the nonwoven fabric in the present invention contains 100% of the main monomer.
Silane monomer per part by weight (solid content equivalent)
The first requirement is to use it in an amount of 0.1 to 10.0 parts by weight (solid content equivalent). The second requirement is to use 1.0 to 200 parts by weight (in terms of solid content) of the colloidal silica.
Furthermore, emulsion polymerization of (a) the main monomer, (b) the silane monomer, and (c) colloidal silica in an aqueous system in the presence of an anionic surfactant and/or a nonionic surfactant results in such an aqueous resin dispersion. This is the third requirement for liquid. In the present invention, by using an adhesive that satisfies all of the above requirements, the resulting nonwoven fabric retains its soft texture, is non-sticky, and has excellent strength, durability such as solvent resistance, and heat resistance. An excellent nonwoven fabric can be obtained. The reason why a nonwoven fabric using an adhesive that satisfies the above conditions in the present invention can exhibit the above effects is not necessarily clear, but during emulsion polymerization in the production of an adhesive, the surface of the silane monomer and colloidal silica - It is thought that it reacts with OH groups and crosslinks, resulting in the formation of an organic-inorganic hybrid emulsion.
This is thought to be due to the formation of a strong organic-inorganic composite film on the nonwoven fabric. Among the main monomers used as a component of the adhesive, α,β-monoethylenically unsaturated carboxylic acid alkyl esters include acrylic acid and 1 to 18
Preferred are esters with alkanols having 5 carbon atoms, such as methyl acrylate, ethyl acrylate, butyl acrylate, isobutyl acrylate, 2-ethylhexyl acrylate, decyl acrylate, dodecyl acrylate, methyl methacrylate, and methacrylic acid. ethyl, butyl methacrylate,
Examples include lauryl methacrylate, 2-ethylhexyl methacrylate, and 2-hydroxyethyl acrylate. Examples of alkenylbenzene include styrene, vinyltoluene, and α-methylstyrene. It is also possible to use copolymerizable α,β-monoethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid, crotonic acid, and itaconic acid as the main monomer. be. In addition, examples of silane monomers, that is, monomers containing a polymerizable unsaturated double bond and an alkoxysilane group, include divinyldimethoxysilane, (CH ₂ =CH) ₂ Si
( _OCH3 ) ₂ , _divinyl -β-methoxyethoxysilane ( _{CH2 = CH} ) _2Si ( _OCH2CH2OCH3 ) ₂ , vinyltriethoxysilaneCH2=CHSi( _OCH2CH3 ) _{3 ,}
Vinyltris-β-methoxyethoxysilane _CH2
=CHSi _{( OCH2CH2OCH3 ) 3} , γ-methacryloxypropyltrimethoxysilane Examples include di- or trialkoxysilane compounds such as. Furthermore, colloidal silica is usually an aqueous dispersion with SiO ₂ as the basic unit, and the particle size is 4 to 4.
It is 100 μm. The state of the colloidal silica dispersion can be either acidic or basic, and can be appropriately selected depending on the conditions during emulsion polymerization. As acidic colloidal silica, for example, the product name Snotex O
(manufactured by Nissan Chemical Industries, Ltd.) can be used. On the other hand, examples of basic colloidal silica include Snowtex 20, Snowtex 30, Snowtex
40, Snowtex C, Snowtex N (manufactured by Nissan Chemical Industries, Ltd.), etc. can be used. In the adhesive used for manufacturing the nonwoven fabric of the present invention, the above-mentioned (a) main monomer, (b) silane monomer, and (c)
The copolymerization ratio of colloidal silica is (a):(b):(c)=
It is an essential condition that the ratio is 100:0.1 to 10.0:1.0 to 200 (solid content weight ratio), preferably (a):(b):(c)=
100:0.2~5.0:2.0~150 is desirable.
Silane monomer per 100 parts by weight of main monomer
When the amount is less than 0.1 part by weight, the reactivity with the -OH group on the surface of colloidal silica is insufficient, making it impossible to obtain a preferable organic-inorganic hybrid polymer having cross-linked bonds, resulting in poor durability, heat resistance, etc. of the nonwoven fabric. No improvement in physical properties was observed, which is not preferable. In addition, if the silane monomer exceeds 10.0 parts by weight, the reaction with the -OH group on the surface of colloidal silica will be excessive and an aqueous resin dispersion will not be obtained, or even if it is obtained, the stability of the dispersion will be poor and undesirable. do not have. Furthermore, when the amount of colloidal silica is less than 1.0 parts by weight based on 100 parts by weight of the main monomer, it is impossible to obtain an adhesive based on a strongly bonded organic-inorganic hybrid type polymer having cross-linked bonds; The resulting nonwoven fabric is not preferred because no improvement in physical properties such as durability and heat resistance is observed. Furthermore, the main monomer
If the amount of colloidal silica exceeds 200 parts by weight per 100 parts by weight, the adhesive will become brittle, and the durability of nonwoven fabrics made using such an adhesive will be significantly reduced, which is not preferable. The nonwoven fabric of the present invention is made by bonding the adhesive obtained as described above to a web. The fibers forming this web include cotton, natural fibers such as hemp,
One or more types of synthetic fibers such as synthetic fibers and regenerated fibers such as rayon, artificial fibers such as cellulose acetate, polyamide fibers, polyester fibers, acrylic fibers, polyolefin fibers, and polyurethane fibers are used. Also, the web is about 10 per ^square meter.
A suitable weight is between g and 200g, preferably 1m ²
Approximately 20g to 150g per serving. The amount of adhesive applied to the web is approximately 20% to 20% dry weight of adhesive to the weight of the web.
A suitable range is 100% or more than 100%, preferably about 30-60%. The method of adhering the adhesive to the web in the present invention is not particularly limited. For example, the adhesive may be applied by a wet method in which the web is immersed in an aqueous dispersion containing colloidal silica, which is the adhesive of the present invention, and wiped off, or the adhesive may be applied to a dry nonwoven fabric made by a needle punch method or a spunbond method. Then, an aqueous dispersion containing colloidal silica may be applied later by a method such as a dipping method, a spray method, or a coating method. The nonwoven fabric thus obtained has a flexible texture but is not sticky due to the formation of a strong organic-inorganic hybrid type composite film with favorable properties, and has a high degree of strength and solvent resistance. It is recognized that it has excellent performance such as durability, heat resistance, etc. In addition, it does not generate formaldehyde and can be obtained using a wide range of webs including natural fibers, recycled fibers, inorganic fibers, and synthetic fibers, so it can be used in a wide variety of applications such as clothing, sanitary materials, and various industrial materials. It can be used for. Production Examples, Examples and Comparative Examples are given below to specifically explain the present invention. In addition, "parts" and "%" in the examples are completely based on weight. Production example 1 (Production of aqueous dispersion) (1) Polymerizable monomer 2-ethylhexyl acrylate 45.0 parts Methyl methacrylate 54.0〃 Acrylic acid 1.0〃 γ-methacryloxypropyltrimethoxysilane 0.5〃 (2) Surfactant lauryl sulfonic acid Sodium 3.0 parts (3) Colloidal Silica Notex 30 (manufactured by Nissan Chemical Industries, Ltd. Solid content)
30%) 15.0 parts (4) Ion-exchanged water (5) Polymerization initiator Ammonium persulfate 0.5 parts Sodium bisulfite 0.2〃 Surfactant, colloidal in a flask equipped with a stirring device, cooling tube, dropping device, and N ₂ gas inlet Prepare silica and ion exchange water and place under nitrogen gas flow.
The mixture is heated to 60°C, a polymerization initiator is added, and a polymerizable monomer is added dropwise over 180 minutes. The reaction temperature at this time was adjusted to a range of 60 to 70°C. After completion of the dropwise addition, the mixture was stirred at that temperature for 2 hours, cooled, and adjusted to a pH of 8 to 9 and a solid content of 40% with aqueous ammonia of about 14% concentration to obtain a stable resin dispersion. Production Examples 2 to 6 (Production of aqueous resin dispersion) Resin dispersions were produced in the same manner as in Production Example 1 above, based on the raw materials shown in Table 1.

[Table] (Note) Snowtex*: Production Examples 7 to 10 of Nissan Chemical Industries, Ltd. (Production of aqueous resin dispersion) Based on the raw materials shown in Table 2, resin dispersions were produced in the same manner as in Production Example 1 above.

[Table] Examples 1 to 4, Comparative Examples 1 to 4 Each adhesive was created by diluting the aqueous resin dispersions prepared in Production Examples 1 to 4 and 7 to 10 with water to a solid content of 30%. did. The adhesive was applied to 150 g/ ^m2 of a fiber web having a fiber composition of 60% polyester fibers of 3.0 denier/51 mm and 40% rayon fibers of 3.0 denier/51 mm at a fiber/adhesive solids ratio of approximately 1. /0.6.
Next, each nonwoven fabric was dried in a hot air circulation dryer at 100°C for 10 minutes. The physical properties of each of the obtained nonwoven fabrics are shown in Tables 3 and 4. The physical properties in the table were measured as follows. (Test method) Weight (g/m ² ): According to JIS-L-1085. Thickness (mm): According to JIS-L-1085. 5% modulus (Kg/5cm): According to JIS-L-1085. Strength (Kg/5cm): According to JIS-L-1085. Tear strength (Kg): According to JIS-L-1085C. Bending resistance (g): Hydroometer method Dry cleaning resistance: According to JIS-L-1085. 〇 Good, △ Fair, × Bad Drapability: Conforms to JIS-L-1085. 〇 Good, △ Acceptable, × Not acceptable Formaldehyde amount: Acetylacetone method Ministry of Health and Welfare Ordinance No. 34 Texture: Feel by texture

【table】

[Table] Examples 5-6, Comparative Examples 5-7 The solid content of the aqueous resin dispersions of Production Examples 5-7 and 9
The adhesive was diluted with water to a concentration of 30%, and then 0.1% of Antifoam R-490 (a silicone antifoaming agent manufactured by Dainippon Ink and Chemicals) was added as an antifoaming agent. 50% 3.0 denier/51mm polyamide fiber and 50% 3.0 denier/51mm rayon fiber
Each of the adhesive and commercially available acrylic resin emulsion was applied to both sides of the web at a fiber/adhesive solids ratio of approximately 1/0.5 to 120 g/ ^m2 of a fiber web having a fiber composition of Spray application was performed using an airless sprayer. Next, it was dried in a hot air circulation dryer at 120°C for 10 minutes to obtain a nonwoven fabric. The physical properties of each of the obtained nonwoven fabrics are shown in Table 5.

【table】

Claims (1)

[Claims] 1 In a nonwoven fabric bonded with an adhesive, the adhesive includes (a) 100 parts by weight (in terms of solid content) of at least one monomer selected from α,β-monoethylenically unsaturated carboxylic acid alkyl esters and alkenylbenzenes; ) as opposed to (b) a monomer containing a polymerizable unsaturated double bond and an alkoxysilane group in the molecule.
0.1 to 10.0 parts by weight (in terms of solid content) (c) 1.0 to 200 parts by weight (in terms of solid content) of colloidal silica are emulsion polymerized in an aqueous system in the presence of an anionic surfactant and/or a nonionic surfactant. A nonwoven fabric made using an aqueous resin dispersion obtained by