JPH0292984A - Elastic rubber-like acrylic sealing composition and production thereof - Google Patents

Abstract

PURPOSE:To obtain the subject sealing composition excellent in follow-up adhesion to rugged surface, application properties, heat resistance and weather resistance by irradiating a liquid mixture composed of specified vinyl monomers and a photopolymerization initiator with ultraviolet rays and polymerizing the monomers. CONSTITUTION:To (A) 100 pts.wt. mixture composed of normally (i) 100-60wt.% (meth)acrylic alkylate and (ii) 0-40wt.% another vinyl monomer copolymerizable with the component (i) (B) a photopolymerization initiator consisting of benzoin ethyl ether, benzoin isopropyl ether, hydroxycyclohexyl phenyl ketone, benzyl dimethyl ketal, etc., is added, preferably in an amount of 0.001-5 pts.wt. The resultant liquid mixture is irradiated with ultraviolet rays, normally in 0.1-100mw/cm<2> light intensity for polymerization of the component (A), thus obtaining the objective sealing composition.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an elastic rubber-like acrylic sealant particularly suitable for use in buildings and automobiles, and a method for producing the same.

(Conventional technology) Sealants include polysulfide, silicone,
Examples include modified silicone, polyurethane, acrylic, butyl rubber, and SBR. These are generally in the form of a high viscosity paste.

This type of paste sealing material hardens into an elastic rubber-like material after application, and therefore has excellent adhesion to uneven surfaces. However, since it is in the form of a paste, it takes time and effort to apply, and requires hardening and aging, resulting in poor workability.

Among various sealing materials, a few butyl rubber-based sealing materials are commercially available as elastic rubber-like sealing materials. This elastic rubber-like butyl rubber sealant is
It only needs to be sandwiched between adherends, does not require hardening and aging, and has better workability than paste sealants.

Such elastic rubber-like butyl rubber sealing materials are non-crosslinked and generally contain a softening agent in order to improve their conformability to uneven surfaces, and are susceptible to plastic deformation. Therefore, when used for construction or automobiles, for example, the sealants stick together or stick to other places, especially in the summer, resulting in insufficient workability and poor heat resistance and weather resistance after installation. Sexuality was also insufficient.

(Problems to be Solved by the Invention) The present invention solves the above problems, and its purpose is to provide excellent follow-up adhesion to uneven surfaces, as well as excellent workability, heat resistance, and weather resistance. An object of the present invention is to provide an excellent elastic rubber-like acrylic sealant and a method for producing the same.

(Means for Solving the Problems) The elastic rubber-like acrylic sealing material of the present invention is produced by applying ultraviolet rays to a liquid material in which a photopolymerization initiator is added to a vinyl monomer containing (meth)acrylic acid alkyl ester as a main component. The vinyl monomer is polymerized by irradiation.

In addition, the method for manufacturing the zero-starter elastic rubber-like acrylic sealant includes injecting the above-mentioned liquid into a removable mold, or pouring the above-mentioned liquid into water or a mixture of water and alcohol using a long and thin rod. It is characterized by extruding it into a shape and irradiating it with ultraviolet rays to polymerize the vinyl monomer.

In the present invention, the vinyl monomer whose main component is an alkyl (meth)acrylate is generally 100 to 60% by weight of an alkyl (meth)acrylate and 0 to 40% by weight of another vinyl monomer copolymerizable therewith. It consists of %. As the (meth)acrylic acid alkyl ester, a (meth)acrylic acid alkyl ester in which the alkyl group has 1 to 14 carbon atoms, preferably 4 to 12 carbon atoms is used, such as n-butyl (meth)acrylate,
2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, isononyl (meth)acrylate, and the like are preferably used.

The other copolymerizable vinyl monomers mentioned above are generally used for the purpose of adjusting the flexibility and adhesiveness of the sealant. Examples of these vinyl monomers include acrylic acid, methacrylic acid, acrylamide, acrylonitrile, methacrylonitrile, N-substituted acrylamide,
Hydroxyethyl acrylate, N-vinylpyrrolidone, maleic acid, itaconic acid, N-methylolacrylamide, hydroxyethyl methacrylate, and the like are used. Furthermore, vinyl monomers such as tetrahydrofurfuryl acrylate, polyethylene glycol acrylate, and polypropylene glycol acrylate, which yield polymers with a low glass transition temperature, can also be used.

As the photopolymerization initiator, one having an active site in the wavelength range of 300 to 400 runs and having high initiation efficiency is preferably used. Examples include benzoin ethyl ether, benzoin isopropyl ether, hydroxycyclohexylphenyl ketone, benzyl dimethyl ketal, and the like.

These photopolymerization initiators are
It is preferable that it is added at a ratio of o, ooi to 5 parts by weight based on parts by weight. When the amount added is less than 0.001 parts by weight, the photopolymerization initiator is consumed by light energy at the early stage of the reaction, so a large amount of monomer tends to remain.
Not only will the odor of snails remain, but the heat resistance and adhesion of the sealant will deteriorate. On the other hand, when the amount of photopolymerization initiator added exceeds 5 parts by weight, the polymerization reaction rate becomes faster, but the decomposition odor of the photopolymerization initiator becomes more intense, and the performance of the sealing material decreases and variations occur. growing. Therefore, the amount of photopolymerization initiator added is adjusted depending on the target performance.

In the present invention, a photocrosslinking agent made of a polyfunctional acrylic monomer may be added together with the above photopolymerization initiator. Such photocrosslinking agents include hexanediol di(meth)acrylate, (poly)ethylene glycol di(meth)acrylate, and neopentyl glycol di(meth)acrylate.
meth)acrylate, pentaerythritol di(meth)
Acrylate, trimethylolpropane tri(meth)
Acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, etc.

These photocrosslinking agents are preferably added in a proportion of generally 5 parts by weight or less to 100 parts by weight of the vinyl monomer. When such a photocrosslinking agent is used, crosslinking bonds are generated between polymer molecules during the photopolymerization reaction of the vinyl monomer, and the heat resistance of the sealing material is further improved. When the amount of the photocrosslinking agent added exceeds 5 parts by weight, heat resistance is improved, but conformability and adhesion to uneven surfaces are slightly reduced.

In addition, in the present invention, a thickener, a thixotropic agent,
Commonly used compounding agents such as extenders and fillers may also be added.

Examples of thickeners include acrylic rubber and epichlorohydrin rubber, and examples of thixotropic agents include Aerosil and polyvinylpyrrolidone. In addition, fillers include calcium carbonate, titanium, clay, etc., and fillers include inorganic hollow bodies such as glass balloons, alumina balloons, and ceramic balloons, organic spherical bodies such as nylon beads, acrylic beads, silicon beads, and chloride. There are organic hollow bodies such as vinylidene balloons and acrylic balloons, and short fibers such as polyester, rayon, and nylon.

When the liquid material of the vinyl monomer is thickened by adding 1 to 10 parts by weight of the above-mentioned thickener or thixotropic agent, the work of pouring this liquid into a mold or extruding it into water becomes easier. In addition, the shape can be easily maintained in a mold or underwater. In addition to using the above-mentioned thickeners or thixotropic agents, methods for thickening the vinyl monomer liquid include, for example, irradiating a small amount of ultraviolet rays to partially polymerize the vinyl monomer in advance.

In addition, if about 20 to 60 volume % of microspheres with an average particle diameter of about 10 to 200 μ- are added to the liquid vinyl monomer as the filler to make the sealant contain the microspheres, the unevenness of the sealing material can be improved. Improves adhesion to surfaces. Instead of adding the above-mentioned filler, by mixing and stirring gas into the liquid vinyl monomer and foaming, the sealant contains about 5 to 70% by volume of closed cells, which can be applied to the uneven surface of the sealant. It is also possible to improve the adhesion of

In the present invention, (meta) prepared as described above
A liquid material of a vinyl monomer whose main component is an acrylic acid alkyl ester is poured into a releasable mold to obtain a sealant in a desired shape, and the mold is irradiated with ultraviolet rays.

The above liquid is purged with an inert gas such as nitrogen gas to remove dissolved oxygen before being poured into the releasable mold. Further, without purging with inert gas, a compound having an oxygen removing effect such as phenyl diisodecyl phosphite, triisodecyl phosphite, and stannous octoate may be added.

When using an open mold as the mold, ultraviolet irradiation is performed using air (
The process is carried out in a box inertized with nitrogen gas to prevent contact with oxygen (oxygen), and through quartz glass, pyrex glass, or boric acid glass. In addition, without using an inert box, we temporarily cover the surface of the injected liquid with a releasable polyester film to prevent contact with air (oxygen) and prevent ultraviolet irradiation. You may do so.

In this case, it is preferable to add the compound having an oxygen removing effect to the liquid material.

The ultraviolet lamp used for irradiation has a wavelength of 300~
Those having a spectral distribution in the 400 nm region are used, and examples thereof include chemical lamps, black light lamps (trade name of Toshiba Denzai ■), low-pressure, high-pressure, and ultra-high-pressure mercury lamps, and metal halide lamps. Previous 2
One lamp is used to obtain relatively low light intensity and the last four lamps are used to obtain relatively high light intensity. However, the light intensity generally varies from 0°1 to 100 mW depending on the distance to the irradiated object and adjustment of the voltage.
(milliwatt)/C, and is set according to the required quality of the sealant.

Increasing the light intensity lowers the molecular weight of the polymer, but shortens the polymerization reaction time. Conversely, when the light intensity is lowered, the molecular weight becomes higher but the polymerization reaction time becomes longer. Therefore, when maintaining proper follow-up adhesion to an uneven surface and placing particular emphasis on heat resistance, a lamp with low light intensity is used. On the other hand, if proper heat resistance is to be maintained, and especially adhesion to uneven surfaces is important, a lamp with high light intensity is used.

Upon irradiation with ultraviolet rays, a vinyl monomer containing (meth)acrylic acid alkyl ester as a main component is polymerized in the mold to produce a polymer. By peeling this polymer from the mold, a sticky, elastic, rubber-like acrylic sealant is obtained.

This sealant is generally manufactured into a product by covering it with a protective release paper or the like.

When using a releasable mold as described above, the sealant is obtained in a shape corresponding to the mold in a batch process. When obtaining the sealant as a continuous elongated product, the following method is suitably employed.

That is, as shown in FIG. 1, a synthetic resin strip film 11 made of polyester, polypropylene, polyethylene, polyvinyl chloride, etc. that has been treated with a silicone release agent or the like.
is passed through a box 21 inertized with nitrogen gas, etc., and bent into a groove shape, for example, to form a removable elongated mold 12.
form.

Then, a vinyl monomer liquid 31 is injected into the elongated mold 12 from a nozzle 41. Liquid substance 3 above
1 is purged in the tank 42 with nitrogen gas or the like to remove dissolved oxygen, and is pushed out from the nozzle 41 by the pump 43.

The liquid material 31 in the elongated mold 12 moves inside the box 21 together with the mold 12, and ultraviolet light is irradiated from the ultraviolet lamp 23 through the quartz glass, pyrex glass, or borate glass 22 at the top of the box 21.

By irradiating this ultraviolet ray, (meta) is formed in the elongated mold 12.
A vinyl monomer containing an acrylic acid alkyl ester as a main component is polymerized to produce a polymer. By continuously winding up this polymer together with the elongated mold 12 onto a roll without peeling it off from the elongated mold 12, a rolled body 13 of a sticky and elastic rubber-like acrylic sealing material is obtained, which can be used as a product as it is. be done.

Alternatively, as shown in FIG.
A liquid material 51 of vinyl monomer that has been inertized inside is pumped into water or a mixture of water and alcohol 72 in a tank 71 through a nozzle 61 attached to the tip of a flexible tube 64 by a roller pump 63. Extrude into a long and thin rod. When the liquid material 51 is extruded into water or a mixture of water and alcohol 72 in this manner, contact with air (oxygen) is effectively prevented.

In this case, the water or water/alcohol mixture 72 in the oak 71 is purged with nitrogen gas or the like discharged from the pipe 73 to remove dissolved oxygen.

Further, the liquid substance 51 has a viscosity of 50 to 10,000 at 20°C so that the elongated rod-like shape is easily maintained.
The viscosity is increased to about 0 cps. In addition, 0°01 to 10% of surfactant is added to the water or the mixed liquid 72 of water and alcohol.
It is preferable to add a certain amount of alcohol to form an interface between the elongated rod-like material 52 and water or the mixed liquid 72 of water or water and alcohol, since this stabilizes the shape of the elongated rod-like material 52. Also,
As the vinyl monomer constituting the liquid material 51, it is preferable to use a monomer that does not dissolve in water or the mixed liquid 72 of water and alcohol.

Further, a long and thin rod-shaped object 52 extruded from the nozzle 61
is spirally formed into water or a mixture of water and alcohol 7
In order to prevent this, it is preferable that the elongated rod-like object 52 is allowed to fall along the thread 81.

When such a thread 81 is used, the thread 8 is contained in the sealant.
1 exists, and the ease of manual cutting during sealant construction work is also improved.

The elongated rod-like object 52 extruded into the water or water/alcohol mixture 72 is exposed to ultraviolet light from the ultraviolet lamp 74 through the quartz glass, pyrex glass, or boric acid glass 73 on the side of the tank 71. irradiated.

By this irradiation with ultraviolet rays, a vinyl monomer containing (meth)acrylic acid alkyl ester as a main component is polymerized to produce a polymer. By pulling out this polymer from the tank 71 and drying it, an acrylic sealing material 53 having an adhesive and elastic rubber shape is obtained. This sealing material 53
The product is then covered with a protective release paper and wound into a roll.

(Function) In the present invention, a vinyl monomer containing an alkyl (meth)acrylic acid ester as a main component is polymerized by irradiation with ultraviolet rays. Since this polymerization is bulk polymerization, a polymer having a high molecular weight and viscoelasticity is produced. Also,
It is possible to obtain a high gel content with a low crosslinking point density.

(Example) Examples of the present invention will be shown below.

Place 95 parts by weight of 2-ethylhexyl acrylate (2EHA), 5 parts by weight of acrylic acid (AA), and 0.1 part by weight of benzyl dimethyl ketal as a photopolymerization initiator into a separable flask and stir to uniformly distribute the backing soil. Mixed. This mixture was purged with nitrogen gas to remove dissolved oxygen, and then irradiated with ultraviolet light using a chemical lamp to prepare a thickened liquid. The monomer conversion rate of this liquid was 7%, and the viscosity at 20°C was 60,000 cps.

Using this liquid material, an elastic rubber-like acrylic sealant was manufactured by the method shown in FIG.

The diameter of this sealant is 10sφ, the manufacturing speed is 0.3m/min, and the oxygen concentration inside the box is 0.1%.
The ultraviolet rays were irradiated using a chemical lamp for 5 minutes, and the light intensity was 2.5 mW/cffl (wavelength: 360 nm).

The resulting elastic rubber-like acrylic sealant is very sticky, with an elongation of 2000% and an elastic modulus of 5 g/m.
m” (0 to 40%), and the gel fraction was 15% (in this case, a gel fraction occurs even without adding a photocrosslinking agent).Also, the residual monomer was 0.1%, which was a practical problem. In addition, in conventional commercially available elastic rubber-like butyl rubber sealing materials with a diameter of 10 mm, the elongation was 2000.
%, the elastic modulus was 3 g/m+n'' (0 to 40%), and the gel fraction was 0%.

Example 1" 1 and 2U Hexanediol diacrylate is used as a photocrosslinking agent, and the amount of this photocrosslinking agent is varied. Alternatively, 2-ethylhexyl acrylate (2EHA) and acrylic acid (A
The same procedure as in Example 1 was carried out except for changing the blending ratio with A) or changing the light intensity of irradiation. The results are summarized in Table 1.

Using 0.05 parts by weight of hexanediol acrylate as a crosslinking agent, 2-ethylhexyl acrylate (2EH
A) and other vinyl monomers that can be copolymerized with it, such as acrylic acid (AA) and vinyl pyrrolidone (VP).
, tetrahydrofurfuryl acrylate (THFA),
Same as Example 1 except that cyclohexyl acrylate (CHA), polyethyl glycol acrylate (PEGA), polypropylene glycol acrylate (PPC, A), and hydroxyethyl acrylate (HEA) were used and the blending ratio of these was changed. I did it. The results are summarized in Table 2.

70 parts by weight of 2-ethylhexyl acrylate (2EHA), 30 parts by weight of cyclohexyl acrylate (CHA), and 0.1 parts by weight of pencil dimethyl ketal as a photopolymerization initiator.
Parts by weight were mixed and a thickened liquid was prepared in the same manner as in Example 1. The monomer reaction rate of this liquid is 6%, 20
The viscosity at °C was 80,000 cps.

Using this liquid material, an elastic rubber-like acrylic sealing material containing threads was manufactured by the method shown in FIG. The diameter of this sealant is 10mmφ, and the manufacturing speed is 0.2m.
/min, and a mixed solution of 30% by volume of water and 70% by volume of methyl alcohol was used. Ultraviolet irradiation was carried out using a chemical lamp for 15 minutes, and the light intensity was 2.5 mW/cd.
(wavelength: 360 nm).

The resulting elastic rubber-like acrylic sealant was protected with a highly tacky, peelable polyester film and rolled into a product. The elongation of this sealant is 1300%, and the elastic modulus is Log/+nm" (0 to 40%
), the gel fraction was 0%.

(Left below) A rod-shaped acrylic sealing material with a diameter of 101 IIlφ obtained in Example 1 and a commercially available rod-shaped butyl rubber sealing material with a diameter of 10 amφ were prepared.

This sealant was glued in a semicircular shape with a diameter of 20 cm to an aluminum plate that had been treated with unevenness using sand-containing paint (maximum height of unevenness: 2 mm), water was poured into the semicircle, and a glass plate was glued to this. .

During the above bonding, all of the sealants leaked water when lightly crimped, but when tightened using metal fittings, none of the sealants leaked, and the follow-up adhesion to the uneven surface was good.

When this was left at 60°C for one week, the adhesive surface of the butyl rubber sealant expanded by about 3 times and its heat resistance was inferior, but the adhesive surface of the acrylic sealant expanded by about 1.5 times. It had little spread and good heat resistance.

After that, the metal fittings were removed, but no water leakage occurred with any of the sealants. However, when the glass plate was peeled off with gentle force, the butyl rubber sealant remained with cracked adhesive, but the acrylic sealant was slightly deformed but did not crack at all, and everything was fine. I was able to remove it.

Further, when a weather resistance test was conducted on the above-mentioned acrylic sealant and butyl rubber sealant, the acrylic sealant was superior. However, when using a butyl rubber sealant, the sealants tend to stick to each other and are more difficult to handle than acrylic sealants.

(Effects of the Invention) As described above, the present invention polymerizes a vinyl monomer containing an alkyl (meth)acrylic acid ester as a main component by irradiating it with ultraviolet rays, thereby forming a flexible and elastic rubber-like material. , it is possible to obtain an acrylic sealing material that has excellent conformability to uneven surfaces, as well as excellent workability, heat resistance, and weather resistance.

Further, in the present invention, since the vinyl monomer is polymerized by bulk polymerization by irradiation with ultraviolet rays, the polymerization cost is lower than thermal polymerization using a solvent or an aqueous medium.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram for explaining one example of the method of the present invention, and FIG. 2 is an explanatory diagram for explaining another example of the method of the present invention. 31, 51...-Liquid material of vinyl monomer, 12-...
- Peelable elongated mold, 72- Water or a mixture of water and alcohol, 23.74... Ultraviolet lamp, 13.53-
Sealing material.

Claims (1)

[Scope of Claims] 1. Elasticity obtained by polymerizing the vinyl monomer by irradiating ultraviolet rays to a liquid material in which a photopolymerization initiator is added to a vinyl monomer containing (meth)acrylic acid alkyl ester as the main component. Rubbery acrylic sealant. 2. A liquid material containing a photopolymerization initiator added to a vinyl monomer mainly composed of (meth)acrylic acid alkyl ester is poured into a removable mold, and the mold is irradiated with ultraviolet rays to polymerize the vinyl monomer. A method for producing an elastic rubber-like acrylic sealant, characterized by: 3. A liquid product made by adding a photopolymerization initiator to a vinyl monomer containing (meth)acrylic acid alkyl ester as the main component is extruded into a long and thin rod shape into water or a mixture of water and alcohol, and then exposed to ultraviolet rays. A method for producing an elastic rubber-like acrylic sealant, which comprises polymerizing the vinyl monomer by irradiation.