JPS5842209B2 - Heat-expandable resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel thermally expandable resin composition, and more particularly to the above composition useful as a thermally expandable printing ink or a thermally expandable paint.

Conventionally, foamable or thermally expandable printing inks or coatings have been described, for example, in U.S. Pat. No. 3,615,972;
It is publicly known in Japanese Patent Laid-open Nos. 49-32,966, 5053.111, and 51-102,191.

Thermal expansion agents (
Both blowing agents) use a thermal expansion agent called microspheres, which is a low-boiling hydrocarbon encapsulated in a vinylidene chloride-acrylonitrile copolymer. There is a disadvantage that unreacted monomers such as acrylonitrile remain dissolved in low-boiling hydrocarbons, causing various problems during use.

The present inventors developed a thermal expansion agent with a small particle size and no worries about residual monomers, and as a result of intensive research to obtain new thermal expansion printing inks and paints, we found that an addition polymerizable agent containing a low boiling point liquid When polymerizing monomers to produce a polymer shell, a combination of polymerization initiators with different decomposition temperatures is used, and the addition polymerization reaction is first almost completed through a (relatively) low temperature polymerization reaction. Then, when using the microscopic bodies obtained by polymerizing the small amount of monomer that remains inside through a (relatively) high temperature polymerization reaction as a thermal expansion component of thermally expandable printing ink, etc., the residual monomers at the time of use are The present invention was completed based on the finding that the problems caused by staleness do not substantially occur, and sufficient foaming and expansion can be achieved.

That is, the present invention provides a thermally expandable resin composition comprising a solvent, a polymeric binder, and a thermally expandable agent, wherein the thermally expandable agent contains a low-boiling liquid, at least 50% by weight of vinylidene chloride, acrylonitrile, or methacrylonitrile. a polymerization initiator having a decomposition reaction rate constant of the order of about 105 (sec5) at about -10°C to 50'C; An oil-in-water emulsion containing a polymerization initiator having an order of It is characterized by being thermally expandable microscopic bodies with a particle size of about 1 to 500 microns, which are coated with a low-boiling point liquid with an addition polymer film obtained by polymerizing at 60'C to 90C. It is a thermally expandable resin composition.

To explain the present invention in detail, the solvent used in the present invention is not a special medium, such as water or an organic solvent, which has conventionally been commonly used in inks, paints, etc.

Further, the polymer binder used in the present invention is also a common coating-forming resin widely used in conventional water-based and oil-based inks and paints.

Examples of such polymeric binders are also well known and will not be specifically discussed herein.

The thermal expansion agent used in the present invention and which characterizes the present invention will be explained.

Low boiling point liquids are traditionally called physical blowing agents.
Examples include low molecular weight hydrocarbons such as propane, butane, isobutane, pentane, neopentane, hexane, isohexane, and heptane, and halides of methane and ethane.

As the addition polymerizable monomer used in the present invention, conventionally known monomers that give hydrophobic addition polymers are used.
Particularly for the purposes of the present invention, those that produce thermoplastic resin films with low gas permeability are preferred, and for example, vinylidene chloride, acrylonitrile, methacrylonitrile, etc. are preferred as main monomers.

In addition, for the purpose of controlling and improving the thermal expansion temperature of the microscopic bodies, it is also a preferable method to use the above monomers in combination with lower alkyl methacrylates, lower alkyl acrylates, vinyl acetate, vinyl chloride, styrene, etc.

Also, trace amounts of crosslinking monomers such as divinylbenzene and ethylene glycol dimethacrylate, for example 0.05%.
Addition of approximately 5% (by weight) improves the solvent resistance of the polymer shell, expands the range of use to solvent-based applications, and increases the melt viscosity of hot melts, so that the temperature exceeds the softening point of thermally expandable particles. It exhibits excellent practical effects for the purpose of the present invention, such as maintaining the coefficient of thermal expansion with respect to the temperature.

In addition, a (relatively) low-temperature polymerization initiator that starts a polymerization reaction at about -100C to 50C is a polymerization initiator whose decomposition rate constant at about 10C to 50C is on the order of about 1ff5 (sec"). Yes, such as isobutyryl peroxide, tert-butyl peroxyneotecanoate, tert-butyl peroxy pivalate,
Diisopropyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, di-2-ethoxyethyl peroxydicarbonate, acetylcyclohexylsulfonyl peroxide, 2,2 azobis-
A homopolymerization initiator such as 2-cyclopropylpropionitrile and phenylazotriphenylmethane, and a redox polymerization initiator in combination such as benzoyl peroxide-dimethylaniline, and furthermore, a photopolymerization reaction can be initiated by ultraviolet irradiation. Examples include ultraviolet polymerization initiators such as benzoin, benzophenone, 2,2'-azobisisobutyronitrile, and benzoin peroxide.

Furthermore, a (relatively) high temperature polymerization initiator that initiates a polymerization reaction at about 60°C to 90°C is a polymerization initiator that has a decomposition rate constant on the order of about 1O-5 (sec'') at about 60°C to 90°C. Initiators, such as lauroyl peroxide, octanoyl peroxide, decanoyl peroxide, 3,5,5-trimethylhexanoyl peroxide, benzoyl peroxide, tert-butyl peroxyisobutyrate, tert-butyl peroxide,
These include butyl peroxyoftate, 2,2'-azobisisobutyronitrile, etc., and are preferably soluble in monomers and low-boiling liquids.

(The decomposition rate constants of various single polymerization initiators are described in "Polymer Handbook," edited by Brandloop and Inmerdart, described later, page 1-1.

) Next, in the present invention, as a polymerization initiator, a (relatively) low-temperature decomposable one with a temperature difference in the optimum decomposition temperature, and (
We will discuss the advantages of using a relatively high-temperature decomposable material in combination.

If polymer particles containing a liquid swelling agent, such as those used in the application of the present invention, are manufactured by a conventional method, an oil-soluble polymerization initiator is added to an addition polymerizable monomer containing a low-boiling liquid. It is manufactured according to the so-called turbidity polymerization method.
In this case, trace amounts of unreacted monomers tend to remain inside and on the surface of the particles, and on the outside of the medium, but this is undesirable from a sanitary standpoint during the production, storage, and use of the particles. be.

Generally, various methods are used to eliminate residual monomers during polymerization, but in this case, since the polymerization method is suspension polymerization,
Addition of a polymerization initiator, as is done in solution polymerization, has no effect.

In addition, even though the method of volatilization or azeotropic distillation by heating after the polymerization reaction is effective for monomers located outside the particles,
This is not possible for monomers remaining inside, and even for external monomers, it is impossible to treat them at temperatures that would soften the polymer shell, as this would cause the particles to expand. .

Filtering and washing the product is effective for the external part, but the internal part cannot be removed.

Even if a single polymerization initiator or a combination of multiple types is used, using a polymerization initiator that initiates polymerization under similar conditions in a larger amount than normally used will certainly reduce the amount of unreacted monomer remaining. However, it lowers the molecular weight of the resulting polymer, making it difficult to obtain a polymer shell that forms particles with excellent thermal expansion properties.

Therefore, the present inventors discovered that even after the formation of the polymer shell enclosing the liquid swelling agent, a substantially effective amount of the polymerization initiator remained undecomposed, and a trace amount of the remaining unreacted initiator remained. We attempted to solve the above problems by creating a system in which monomers can be subjected to addition polymerization reactions and cycloaddition reactions. We focused on the fact that the decomposition reaction rate of is highly dependent on temperature.

In general, the decomposition rate of an organic free radical polymerization initiator is expressed by the following formula, where the initiator concentration is ■ and the time is t, where kd is the decomposition rate constant, and the decomposition rate constant and half-life t
The relationship with 1/9 is also expressed by the following equation.

The relationship between temperature and decomposition rate constant and half-life of the polymerization initiator is shown in the table below using the example of decomposition of benzoyl peroxide in styrene.

The influence of temperature is very large, and as the temperature drops, the decomposition of the polymerization initiator is extremely reduced.

Furthermore, an example of the decomposition of inbutyryl peroxide in inoctane, which is used as a (relatively) low-temperature polymerization initiator in the present invention, is as shown in the table below. It is decomposing.

[For the decomposition rate formula of the polymerization initiator, the relationship between the decomposition rate constant and the half-life, and the decomposition rate constant of various polymerization initiators, see J. Brandrup, E.
1. "Polymer Handbook" 2nd edition (published by William Interscience Publications in 1975), edited by Immergut, page ll-1 J, C, Masson
“Decomposition rate of organic free radical initiators” (De
Compo-sition Rates of Org
anicFr-ee Radical In1tia
Please refer to the description of tors.

[In other words, in the present invention, the polymerization initiator (i.e., free radical generator) for performing addition polymerization or addition reaction of monomers remaining unreacted after the polymerization reaction is incorporated into the interior of the polymer particles without being substantially decomposed. A (relatively) low temperature polymerization initiator capable of causing a polymerization reaction at a temperature as low as possible to remain is used in an amount necessary for the monomer to be polymerized to an appropriate degree of polymerization,
The resulting addition polymerization reaction is caused to form an addition polymer shell, and the temperature is appropriately raised to decompose the built-in (relatively) high temperature polymerization initiator, and the remaining unreacted monomers are This method aims to solve the problem of residual monomers by polymerizing the monomers by addition polymerization reaction.

As mentioned above, unreacted monomers existing on the outside of the particles to be polymerized, that is, on the surface and in the medium, can be removed by physical operations such as volatilization or azeotropic distillation by reduced pressure or heating, filtration, and washing, as well as water-soluble (relatively) By using a high temperature polymerization initiator such as potassium persulfate, ammonium persulfate, succinic acid peroxide, 4,4'-azobis (4-cyanopentanoic acid, etc.) in combination, unreacted monomers in the aqueous medium can be polymerized. It can be removed.

Based on the method described above, the method for obtaining the thermal expansion agent used in the present invention, that is, the thermally expandable microscopic bodies using the main components described above, is as follows.

The addition-polymerizable monomer is, for example, one or more selected from those listed above.

The amount to be charged is not necessarily specified, but the ratio between the low boiling point liquid and the addition polymer in the final product, which is the microscopic body, is 5%: 95% to 40% = 60%, preferably 10%.
= 90% to 30% = 70% comparison.

Regarding the polymerization initiator, the (relatively) low-temperature polymerization initiator may be used in the amount used in normal polymerization reactions, and preferably in the range of 0.1% to 1% based on the addition polymerizable monomer used. .

The (relatively) high temperature polymerization initiator used to polymerize unreacted monomers is not necessarily specified, and may be in an amount necessary to polymerize remaining unreacted monomers; It may be in the range of 0.01% to 0.1% relative to the body.

Since the polymerization reaction is carried out by a suspension polymerization method, a homogeneous mixture of the above components becomes an oil phase and is dispersed in water as an emulsion.
0 to 10,000 revolutions/min), approximately 1 to 500
It can be made into a micron diameter.

In order to maintain the particle size of these emulsions once formed until the end of the polymerization reaction, high-speed stirring is also a preferred method, but in addition suitable auxiliaries used in conventional suspension polymerization reactions, such as polyvinyl alcohol, Advanced partial hydrolysates of polyvinyl acetate, polyvinylpyrrolidone, polyacrylic acid sorter, hydroxyethyl cellulose, water-soluble polyesters, water-soluble polyamides, etc. are used as suspension stabilizers for water-soluble polymers, and carbonic acid Calcium, calcium phosphate, talc, bentonite, anhydrous silicic acid, diatomite, etc. are used as suspension stabilizers for inorganic sparingly soluble fine powders.

The reaction conditions for the polymerization reaction are as follows: First, the temperature is about -10°C in order to proceed with the polymerization reaction using a (relatively) low-temperature polymerization initiator.
Stirring for about 2 hours to 10 hours, optionally 15 to 20 hours, at a temperature most suitable for decomposition of the initiator at ~50°C;
Keep warm.

Then, in order to advance the polymerization reaction using the (relatively) high temperature polymerization initiator, the mixture is stirred and kept at a temperature of about 60 DEG C. to 90 DEG C., which is most suitable for the decomposition of the initiator, for 2 hours to 10 hours.

Thereafter, the generated fine particles are filtered and washed with water and, if necessary, a solvent such as alcohol or acetone.

It is also possible to obtain powdery fine particles by drying it under reduced pressure.

The object of the present invention can be obtained by blending thermally expandable microscopic bodies as described above into conventional printing inks or paints.
It is added in a proportion of about 1 to 200 parts by weight per 00 parts by weight.

The composition of the present invention thus obtained is suitable primarily as a printing ink, and is printed or coated on various substrates in a desired pattern, and then heated at 50 to 150°C to form a microscopic polymer shell. By heating to a temperature at which it softens and the polymeric binder softens, the printed area expands, giving it a highly textured surface topography.

Next, the present invention will be specifically explained with reference to reference examples and examples.

In the text, parts or percentages are based on weight.

Reference Example 1 A polymerization reaction vessel was charged with 196 parts of water, 25 parts of a 20% aqueous silicic acid dispersion, and 10 parts of a 10% aqueous polyvinylpyrrolidone solution.

were mixed uniformly, added to the polymerization reaction vessel, and stirred at high speed to produce an oil-in-water emulsion with an average particle size of 50 microns or less.

Then, the mixture was heated and a polymerization reaction was carried out at 30°C to 35°C for 10 hours.

Then, in order to polymerize unreacted monomers, the temperature was further increased to 6.
The temperature was raised to 0°C, and the reaction was carried out at 60°C to 75°C for 5 hours.

After the polymerization reaction, the pressure was released and the contents were taken out, filtered and washed with water to obtain an aqueous slurry of white fine particles.

When the dry powder was examined under an electron microscope, it was found to be substantially spherical with a particle size of about 20-50 microns.

The granules expanded approximately 2-5 times when heated at 150'C for 2 minutes.

When a similar expansion test was conducted one month later, the expansion rate remained unchanged.

Furthermore, substantially no monomer remained during this expansion test.

Reference Example 2 In the same manner as in Reference Example 1, using a homogeneous mixed solution in place of the monomer, polymerization initiator, and low-boiling liquid of Reference Example 1, the mixture was heated at 45°C to 50°C for 10
The polymerization reaction was then carried out at 70°C to 85°C for 5 hours.

After the polymerization was completed, the pressure was released and the contents were taken out, filtered and washed with water to obtain an aqueous slurry of white fine particles.

When the dry powder was examined under an electron microscope, it was found to be substantially spherical with a particle size of about 20-50 microns.

When heated at 150°C for 2 minutes, it expanded approximately 3 to 5 times.

Furthermore, substantially no monomer remained during this expansion test.

Reference Example 3 269 parts of water and 20% silicic anhydride aqueous dispersion 2 in a polymerization reactor
5 parts, 10 parts of a 10% partially saponified polyvinyl acetate aqueous solution, and 0.1 part of potassium persulfate were charged.

were mixed uniformly, added to the polymerization reaction vessel, and stirred at high speed to form an oil-in-water emulsion.
The polymerization reaction was carried out at 5°C for 10 hours, then at 60°C to 70°C for 3 hours, and at 75°C to 85°C for 2 hours.

After the polymerization was completed, the pressure was released and the contents were taken out, filtered and washed with water to obtain a slurry of white fine particles.

When the dry powder was examined under an electron microscope, it was found to be substantially spherical with a particle size of about 20-50 microns.

When heated at 150'C for 2 minutes, it expanded approximately 3-5 times.

Further, during this expansion test, virtually no residual snails were observed.

Example 1 20.0 parts of thermally expandable fine particles obtained in Reference Example 1, ethylene-vinyl acetate copolymer emulsion (solid content 55%)
) 74.0 parts, ethylene glycol 5 parts, antifoaming agent 0.5
1 part and 0.5 part of hydroxyethyl cellulose were uniformly mixed to obtain a thermally expandable printing ink composition of the present invention.

A pattern was printed on wallpaper using this composition using a silk screen method, and after drying, the ink layer was heated at 150° C. for 2 minutes, causing the ink layer to expand and bulge due to foaming, resulting in a wallpaper with a beautiful uneven pattern.

Example 2 20.0 parts of thermally expandable fine particles of Reference Example 2, acrylic resin 2
5.0 parts of organic solvent, 3.0 parts of pigment, 0.1 part of antifoaming agent, 1.5 parts of silica, and 0.4 parts of dispersant, and mixed uniformly to obtain the composition of the present invention. A thermally expandable resin composition was obtained.

When this composition is printed with a pattern on polyvinyl chloride wallpaper using a gravure printing method, and after drying is passed through a hot air drying oven at 150°C, the ink area expands and bulges due to foaming, resulting in a wallpaper with a beautiful uneven pattern. It was done.

Example 3 Reference example 1. 20 parts of thermally expandable fine particles, 50 parts of urethane-modified acrylic resin, 1 part of polyfunctional (addition polymerization) acrylic resin
8 parts, 6 parts of acrylic acid ester monomer, 3 parts of photopolymerization initiator, 1 part of leveling agent, and 2 parts of pigment were mixed uniformly to obtain a thermally expandable resin composition of the present invention.

Using this composition, a pattern was printed on polyvinyl chloride tiles using a silk screen method, the surface was heated with an infrared lamp to expand the printed area, and then the printed area was cured by irradiation with ultraviolet light.

The tiles thus obtained had a mechanically strong dog-like pattern and an excellent appearance.

Example 4゜Reference example 3. 20 parts of thermally expandable fine particle powder, 40 parts of acrylic polyol, 20 parts of toluene, 1 part of methyl ethyl ketone
5 parts of pigment, 5 parts of pigment, and trifunctional incyanate were blended and mixed uniformly to obtain a thermally expandable resin composition of the present invention.

Using this composition, a pattern was printed on resin-impregnated paper using an engraved gravure printing plate, and then heat-treated at 160°C to 180°C to obtain resin-impregnated paper having an uneven pattern.

The concavo-convex portions of this product had high mechanical strength and excellent physical properties such as solvent resistance and chemical resistance, making it useful for various uses.

Example 5゜Reference example 2. 10 parts of thermally expandable fine particle powder, 100 parts of polyvinyl chloride for base resin, 7 parts of dioctyl phthalate
0 parts of dibutyl phthalate, 16 parts of dibutyl phthalate, 3 parts of a stabilizer for polyvinyl chloride, and 1 part of a colorant were mixed uniformly to obtain a thermally expandable resin composition of the present invention.

This composition is applied onto the base fabric using a knife coater and the polyvinyl chloride paste resin is then gelled.

Then, it was foamed and expanded at 1600C to 180C to obtain polyvinyl chloride foamed leather.

In addition, the above composition was changed to a composition containing a flame retardant and a filler and treated in the same manner to obtain a polyvinyl chloride wall material.

In any of the above examples, no monomer caused by thermally expandable fine particles was detected.

Claims (1)

[Claims] 1. A thermally expandable resin composition comprising a solvent, a polymeric binder, and a thermally expanding agent, wherein the thermally expanding agent is a low-boiling liquid, an addition polymerizable monomer containing at least 50% by weight of vinylidene chloride, acrylonitrile, or methacrylonitrile. polymerization initiator having a decomposition reaction rate constant of the order of about 10'(sec') at about -10°C to 50°C, and a polymerization initiator having a decomposition reaction rate constant of about 165 (sec') at about 60°C to 90°C. An oil-in-water emulsion containing an ordered polymerization initiator is made, and the temperature is about -10℃~
An addition polymer film obtained by carrying out a polymerization reaction of the monomer at 50°C to form an addition polymer shell, and then polymerizing the remaining monomer at 60°C to 90°C. 1. A thermally expandable resin composition comprising thermally expandable microscopic bodies coated with a low boiling point liquid and having a particle size of about 1 to 500 microns.