JP2002047377A - Polychloroprene latex composition and aqueous adhesives - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polychloroprene latex composition having excellent discoloration resistance, and aqueous adhesives used thereof. SOLUTION: The polychloroprene latex composition comprises chloroprenepolymer, scaly silica, and fine particles of metal oxide. Preferably the polychloroprene latex composition comprises as essential components chloroprenepolymer and composite particles of silica-metal oxides, wherein the composite particles are formed by carrying fine particles of metal oxide on aggregate of primary particles of scaly silica.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a latex composition containing polychloroprene latex, which is used as a raw material for adhesives, binders for nonwoven fabrics, latex-impregnated paper, dipped products and the like.

[0002]

2. Description of the Related Art Conventionally, methods for improving the photo-discoloration resistance of a chloroprene polymer include benzotriazole, benzophenone, triazine, hindered amine, and the like.
A method of blending an organic nickel-based or other organic light stabilizer is known. Japanese Patent Application Laid-Open No. 2000-86821 (applicant: Denki Kagaku Kogyo Co., Ltd.) discloses that a phenolic compound having a specific structure is blended with polychloroprene latex to improve discoloration to ultraviolet rays having a wavelength of less than 300 nm. is suggesting. However, most of the organic light stabilizers and phenolic compounds described above are insoluble in water, so that they are difficult to mix with the polychloroprene latex composition, and may cause problems in long-term storage stability. In addition, many of the above organic light stabilizers have a yellow or green color tone, and when the amount of these compounds is large, the hue of the polychloroprene latex composition may be affected. For this reason, there has been a demand for a novel compounding formulation capable of imparting light discoloration resistance to the polychloroprene latex composition.

[0003]

An object of the present invention is to provide a novel formulation of a polychloroprene latex composition having excellent light discoloration resistance.

[0004]

Means for Solving the Problems As a result of repeated studies to achieve the above object, the present inventors have found that a polychloroprene latex having excellent light discoloration resistance can be obtained by blending flaky silica and metal oxide fine particles. The inventors have found that a composition can be obtained, and have completed the present invention. In this case, it is preferable that the metal oxide fine particles are mixed in a state of silica-metal oxide composite particles in which the metal oxide fine particles are supported by an aggregate of flaky silica primary particles.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The chloroprene polymer contained in the polychloroprene latex composition of the present invention is 2-chloro-1,3-butadiene (hereinafter referred to as chloroprene).
Or a copolymer obtained by copolymerizing chloroprene with one or more monomers copolymerizable with chloroprene. Examples of monomers copolymerizable with chloroprene include, for example, 2,3-dichloro-1,3-butadiene, 1-chloro-1,3-butadiene, butadiene, isoprene, styrene, acrylonitrile, acrylic acid and esters thereof. , Methacrylic acid and esters thereof, and two or more of them may be used as necessary.

[0006] The chloroprene polymer in the present invention is actually compounded in the form of a latex obtained by emulsion polymerization of the above monomers in water. The emulsifier and / or dispersant used for emulsifying the latex is not particularly limited, and various anionic, nonionic and cationic types usually used for chloroprene latex can be used. As the anionic emulsifier, carboxylic acid type,
There are sulfate ester type and the like, for example, alkali metal salt of rosin acid, alkyl sulfonate having 8 to 20 carbon atoms,
Alkyl aryl sulfates, condensates of sodium naphthalene sulfonate and formaldehyde, and the like can be mentioned. Specific examples of the nonionic type include polyvinyl alcohol or a copolymer thereof (for example, a copolymer with acrylamide), polyvinyl ether or a copolymer thereof (for example, a copolymer with maleic acid), polyvinyl pyrrolidone or a copolymer thereof. Examples thereof include polymers (for example, copolymers with vinyl acetate), those obtained by chemically modifying these (co) polymers, and cellulose derivatives (hydroxyethyl cellulose). Specific examples of the cationic type include an aliphatic amine salt and an aliphatic quaternary ammonium salt, and examples thereof include octadecyltrimethylammonium chloride, dodecyltrimethylammonium chloride, and dilauryldimethylammonium chloride.

[0007] The amount of the emulsifier and / or dispersant added to the latex in the present invention is 1
The amount is preferably 0.5 to 20 parts by mass with respect to 00 parts by mass.
If the amount is less than 0.5 parts by mass, the emulsifying power is not sufficient and
If the amount exceeds 0 parts by mass, the adhesive strength of the adhesive will be reduced.

The method for polymerizing the chloroprene polymer in the present invention is not particularly limited, and a polymerization temperature, a polymerization catalyst, a chain transfer agent, a polymerization terminator, a final polymerization rate, demonomerization, concentration conditions and the like are appropriately selected. , It is possible to adjust the solid content concentration, the molecular weight of the toluene-soluble portion, the toluene-insoluble content (gel content), and the like.

[0009] The polymerization temperature of the chloroprene polymer in the present invention is not particularly limited, but the polymerization temperature is preferably 10 to 50 ° C in order to smoothly carry out the polymerization reaction. Polymerization catalysts include sulfates such as potassium persulfate,
Organic peroxides such as -butyl hydroperoxide and the like, and are not particularly limited.

The type of chain transfer agent used for the polymerization is not particularly limited, and those usually used for emulsion polymerization of chloroprene can be used. For example, long-chain alkyl such as n-dodecyl mercaptan or tert-dodecyl mercaptan can be used. Known chain transfer agents such as mercaptans, dialkylxanthogen disulfides such as diisopropylxanthogen disulfide and diethylxanthogen disulfide, and iodoform can be used.

The polymerization terminator (polymerization inhibitor) is not particularly limited. For example, 2,6-tert-butyl-4
-Methylphenol, phenothiazine, hydroxyamine and the like can be used.

The final degree of polymerization of the chloroprene polymer is not particularly limited and can be arbitrarily adjusted, and unreacted monomers are removed by a demonomer operation, but the method is not particularly limited. . Latex containing the chloroprene polymer of the present invention is concentrated or
By diluting with addition of water or the like, the solid content concentration can be controlled to a necessary concentration. Examples of the method for concentration include concentration under reduced pressure, but are not particularly limited. But,
In consideration of the drying speed when the polychloroprene latex composition is used as a binder for an adhesive or a nonwoven fabric, and the storage stability of the composition, the solid content concentration of the latex is preferably 40 to 65% by mass.

The flaky silica of the present invention may be any one as long as the primary particles have a substantially thin plate-like shape, and may be partially or wholly bent or twisted. That is, it is preferable that the maximum thickness of the primary particles observed by a scanning electron microscope, a transmission electron microscope, or an atomic force microscope is 0.001 μm or more and less than 1 μm. The production method of the flaky silica is not particularly limited, and can be obtained by a known production method or by mechanically pulverizing a natural mineral. The primary particles here are:
It is the smallest unit of particles that constitutes a powder or agglomerate without breaking the bonds between molecules.

The metal oxide applied in the present invention is a metal oxide other than silica, and is preferably rutile-type titanium oxide, anatase-type titanium oxide, amorphous titanium oxide, zinc oxide, magnesium oxide, cerium oxide, One or two selected from the group consisting of ferrous oxide, ferric oxide, zirconium oxide, aluminum oxide, antimony trioxide, antimony pentoxide, lead trioxide, lead dioxide, bismuth trioxide, and tungsten oxide It is a mixture of the above, and in particular, one or two selected from the group consisting of rutile titanium oxide, anatase titanium oxide, amorphous titanium oxide, zinc oxide, cerium oxide, ferrous oxide, and ferric oxide With the above mixture, good light discoloration resistance can be obtained.

The metal oxide fine particles of the present invention are fine particles of the above-mentioned metal oxides, and their particle shapes are not particularly limited, and may be spherical, acicular, scale-like (plate-like), spindle-like, polyhedral,
It may be any of irregular shapes and the like, and includes those generally called ultrafine particles. Although the particle diameter of the metal oxide fine particles is not particularly limited, the maximum primary particle diameter observed by microscopy, that is, a scanning electron microscope, a transmission electron microscope, or an atomic force microscope is 0.001 μm or more and 0.5 μm or more.
μm, particularly 0.005 μm or more and less than 0.2 μm, or contained in a powder per unit mass, that is, a specific surface area measured by a gas adsorption method (BET method) specified in JIS R1626. The diameter (average surface area diameter) of the virtual sphere having the average surface area, which is calculated based on the total surface area (m ² / g) of all the primary particles,
0.001 μm or more and less than 0.5 μm, particularly 0.001 μm
It is preferably at least m and less than 0.1 μm. Since metal oxide fine particles having a maximum primary particle diameter measured by a microscope method or an average primary particle diameter measured by a gas adsorption method of less than 0.001 μm have a high cohesive force, they must be uniformly dispersed in a polychloroprene latex composition. Is difficult. When the maximum primary particle diameter measured by a microscope method or the average primary particle diameter measured by a gas adsorption method is 0.5 μm or more, the use of metal oxide fine particles affects the adjustment of the hue of the polychloroprene latex composition. May come out.

The method for producing the metal oxide fine particles is not particularly limited, and may be prepared by mechanical pulverization in addition to various known fine particle synthesizing methods.

The polychloroprene latex composition of the present invention contains a chloroprene polymer, flaky silica, and metal oxide fine particles as essential components. Is supported in the form of silica-metal oxide composite particles, which are supported on aggregates of flaky silica primary particles.
Here, the aggregate refers to an aggregate of apparently independent particles in which a plurality of primary particles are aggregated to form a group.In addition, the carrying is defined as a van der Waals force, an electrostatic force, or any other force. It means that the metal fine particles are adhered, adsorbed, fixed and fixed on the surface of the silica aggregate particles. The composite particles are described in, for example, JP-A-11-11927 (applicant: Dokai Chemical Industry Co., Ltd.) and JP-A-2000-7.
It may be synthesized by a known method described in, for example, Japanese Patent No. 2432 (Applicant: Dokai Chemical Industry Co., Ltd.).

The blending amount of the flaky silica can be arbitrarily determined according to the required performance. In order to uniformly and stably disperse the chloroprene polymer in the polychloroprene latex composition, the chloroprene polymer is reduced to 100 parts by mass in solid content. On the other hand, 0.
001 parts by mass or more and less than 100 parts by mass is preferable, and 0.0
More preferably, it is 1 part by mass or more and less than 50 parts by mass. The blending amount of the metal oxide fine particles can be arbitrarily determined according to the required performance, but in order to disperse uniformly and stably in the polychloroprene latex composition, the chloroprene polymer is added to 100 parts by mass as a solid content. , 0.00
It is preferably from 1 part by mass to less than 20 parts by mass, more preferably from 0.01 part by mass to less than 10 parts by mass.

The polychloroprene latex composition of the present invention contains a chloroprene polymer, flaky silica, and metal oxide fine particles as essential components. Depending on the purpose of use, a compounding agent usually added to the latex, such as a tackifier, is used. Resins, anti-aging agents, pH adjusters, thickeners, vulcanizing agents (crosslinking agents), vulcanization accelerators, curing agents, gelling agents, surfactants, foaming agents, defoaming agents, antibacterial agents, A fungicide, a fragrance, a filler other than flaky silica, and the like can be optionally used. For example, when adjusting the viscosity of the polychloroprene latex composition, a thickener may be added. Specific examples of the thickener include sodium polyacrylate, water-soluble polyurethane, associative polyurethane-based emulsion, and alkali swelling. Acrylic emulsion, carboxymethylcellulose (CMC), methylcellulose (MC), hydroxyethylcellulose (HEC), hydroxypropylcellulose (HP
C), polyvinyl alcohol, synthetic smectite and the like. It is effective to add an inexpensive filler in order to reduce the product cost, and specific fillers include calcium carbonate, aluminum hydroxide, titanium oxide, barium sulfate, and talc.

Of course, the above-mentioned benzotriazole, benzophenone, triazine, hindered amine, organic nickel and phenol organic light stabilizers are added to the polychloroprene latex composition of the present invention and the adhesive using the same. In this case, more excellent light discoloration resistance can be obtained.

An adhesive can be obtained by mixing the polychloroprene latex composition of the present invention with various compounding agents such as tackifier resins usually used for adhesives.
The tackifier resin used for the adhesive is not particularly limited. Specifically, a rosin resin, polymerized rosin resin, alpha-pinene resins, beta-pinene resins, terpene phenol resins, C ₅ fraction petroleum resin, C ₉ fraction petroleum resin, C
₅ / C ₉ fraction petroleum resin, DCPD petroleum resin, alkylphenol resin, xylene resin, coumarone resin, coumarone indene resin and the like. In order to obtain a sufficient initial adhesive strength, a resin having a softening point temperature of 80 to 160C is preferable.

The method of adding the tackifier resin is not particularly limited, but it is preferable to add the tackifier resin as an aqueous emulsion in order to uniformly disperse the resin in the adhesive. Further, a method for producing an aqueous emulsion of a tackifier resin includes a method of dissolving in an organic solvent such as toluene, emulsifying / dispersing in water using an emulsifier, and removing the organic solvent by heating under reduced pressure; And crushed to emulsify /
Although there is a method of dispersing, etc., the former capable of producing a fine particle emulsion is preferable.

The amount of the tackifier resin (solid content)
With respect to 100 parts by mass of the chloroprene polymer as a solid content,
It is preferably from 20 to 100 parts by mass, most preferably from 30 to 70 parts by mass. If the amount is less than 20 parts by mass, the initial adhesive strength is insufficient. If the amount exceeds 100 parts by mass, formation of the adhesive film is hindered, and poor adhesion is likely to occur.

[0024]

EXAMPLES Hereinafter, the effects of the present invention will be described with reference to examples and comparative examples, but these examples do not limit the present invention. In the following description, parts and% are based on mass unless otherwise specified.

[Example 1] Sun Lovely TZ-824 (manufactured by Dokai Chemical Industry Co., Ltd.), which is a composite particle having titanium oxide fine particles and zinc oxide fine particles supported on flaky silica,
0 parts by mass, 2 parts by mass of a polycarboxylic acid-based dispersant Poise 530 (manufactured by Kao Corporation) and 38 parts by mass of pure water were mixed and stirred and dispersed by a ball mill for 4 days.
A 824 50% aqueous dispersion was made. This aqueous dispersion is
This is referred to as an aqueous dispersion A. 6.25 parts by mass of the aqueous dispersion A was mixed with 100 parts by mass of solid content of Denkachloroprene latex ALX-600 (manufactured by Denki Kagaku Kogyo Co., Ltd.) having a solid concentration of 60%, and polychloroprene was mixed. Latex composition A was used. Polychloroprene latex A was evaluated by the following method.

[Method of Evaluating Light Discoloration Resistance] Polychloroprene latex composition A was applied to blotting paper Shim-1 (manufactured by KOKUYO Co., Ltd.) at a rate of 200 g / m ² with a brush and dried at 23 ° C. for 3 hours to obtain a 300 W light bulb. ULTRA-VITALU
Using X SUN LUMP (manufactured by OSRAM / Germany) as a light source, irradiation was performed for 4 to 8 hours in a metal case. In addition,
During irradiation, the temperature inside the metal case is controlled to 50 ° C., and the distance between the light source and the sample is set to 250 mm.
The color tone is a multi-source spectrophotometer Multi Spectro
Color Meter (Suga Test Machine Co., Ltd.)
The yellowness index (YI).

Example 2 An aqueous dispersion A was prepared in the same manner as in Example 1. Tamanol E-100, a tackifying resin emulsion having a solid content concentration of 53%, is based on 100 parts by mass of a denka chloroprene latex ALX-600 (manufactured by Denki Kagaku Kogyo KK) of a polychloroprene latex having a solid content concentration of 60%. (Arakawa Chemical Industry Co., Ltd.) 50 parts by mass in terms of solid content, solid content concentration 1
7% sodium polyacrylate thickener ARON A-
20 L (manufactured by Toagosei Co., Ltd.) in terms of solid content of 0.57
7.5 parts by mass of the aqueous dispersion A was mixed with 6.25 parts by mass of the aqueous dispersion A in terms of solid content to obtain a polychloroprene latex composition B. The light discoloration resistance of the polychloroprene latex composition B was evaluated in the same manner as in Example 1.

[Comparative Example 1] Aqueous dispersion A was converted to a solid content of 100 parts by mass based on 100 parts by mass of a denka chloroprene latex ALX-600 (manufactured by Denki Kagaku Kogyo KK) having a solid content concentration of 60%. 25 parts by mass were mixed to obtain a polychloroprene latex composition C. The light discoloration resistance of the polychloroprene latex composition C was evaluated in the same manner as in Example 1.

Comparative Example 2 Denkachloroprene latex A, a polychloroprene latex having a solid content of 60%
100 parts by mass of LX-600 (manufactured by Denki Kagaku Kogyo Co., Ltd.) is converted to solid content. 50 parts by mass, solid concentration 17
% Sodium polyacrylate thickener ARON A-2
0 L (manufactured by Toagosei Co., Ltd.) was mixed with 0.57 parts by mass of a water dispersion A in terms of solid content and 7.5 parts by mass to obtain a polychloroprene latex composition D. The photochromic resistance of the polychloroprene latex composition D was evaluated in the same manner as in Example 1.

Table 1 shows the results of Examples 1 and 2 and Comparative Examples 1 and 2.
It was shown to.

[Table 1]

Note 1) Polychloroprene latex: Denka chloroprene latex ALX-600 (manufactured by Denki Kagaku Kogyo Co., Ltd.) Note 2) Terpene phenol resin emulsion: Tamanol E-100 (manufactured by Arakawa Chemical Industry Co., Ltd.) Note 3) Polyacrylic acid Sodium-based thickener: Aron A-
20L (manufactured by Toagosei Co., Ltd.) Note 4) Scaly silica-titanium oxide-zinc oxide fine particles: 50% aqueous dispersion of Sun Lovely TZ-824 (manufactured by Dokai Chemical Industry Co., Ltd.)

[0032]

As is clear from Table 1, the polychloroprene latex composition (Example 1) and the water-based adhesive (Example 2) of the present invention are the same as those of the conventional polychloroprene latex composition (Comparative Example 1) and the water-based adhesive. It shows better light discoloration resistance than the adhesive (Comparative Example 2).

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4J002 AC091 DE047 DE077 DE097 DE117 DE127 DE137 DE147 DE157 DJ016 FA016 FB076 FD010 FD040 FD330 GJ01 4J040 CA151 HA136 HA306 JA03 KA03

Claims (3)

[Claims] 1. A polychloroprene latex composition comprising a chloroprene polymer, flaky silica and metal oxide fine particles. 2. A polychloroprene latex composition containing a chloroprene polymer and silica-metal oxide composite particles in which metal oxide fine particles are supported on an aggregate of flaky silica primary particles. 3. An aqueous adhesive comprising the polychloroprene latex composition according to claim 1 or 2 and a tackifying resin.