JPH06322225A - Plastisol composition of excellent pot life - Google Patents

Abstract

PURPOSE:To provide an acrylic-resin-based plastisol composition which can keep excellent flow necessary for coating, molding, etc., even when stored long, can show excellent gelation properties when heated, and can give a gel-like molding of excellent mechanical properties. CONSTITUTION:The composition contains acrylic resin particles each of which consists of a core comprising a resin component mainly consisting of (meth) acrylic acid ester units and a shell comprising a resin component comprising repeating units derived from a monomer having a polar group selected from the group consisting of an acid group, a group of its salt, a hydroxyl group and an ether group.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plastisol composition having an excellent pot life, and more specifically, it maintains excellent fluidity required for coating, molding, etc. even during long-term storage. The present invention relates to an acrylic resin-based plastisol composition that exhibits excellent gelling performance upon heating.

[0002]

2. Description of the Related Art Gaskets, liners, etc. used for sealing container lids, etc. have excellent fluidity, do not contain volatilizing components such as solvents, etc. The plastisol composition is widely used because it has appropriate flexibility and cushioning properties.

This plastisol uses a liquid plasticizer as a dispersion medium and has emulsion-sized or suspension-sized resin particles dispersed therein, and the dispersed state is maintained at room temperature, but the resin particles are dispersed at high temperature. By absorbing the plasticizer, the resin particles are coalesced and plasticized. Although vinyl chloride homopolymers and copolymers have been widely used as resins, it has already been proposed to use acrylic resin plastisols in order to prevent the release of hydrogen chloride into the atmosphere during incineration.

For example, Japanese Examined Patent Publication No. 56-26263 includes particles of a single phase surfactant-free acrylic polymer or copolymer containing at least 60% by weight of alkyl acrylate or methacrylate units. And thus includes a compatible liquid plasticizer whose polymer or copolymer is non-volatile at room temperature and which is not a monomer having the same chemical structure as the monomer of said polymer or copolymer. A heat-coalescent acrylic resin plastisol characterized by being dispersed in a surfactant-free medium is described.

Further, Japanese Patent Publication No. 62-3868 discloses that
In a plastisol based on a methylmethacrylate copolymer in an amount ratio of 10: 3 to 1:10, an organic plasticizer and a filler, the copolymer is compatible with a plasticizer in an amount ratio of 3: 1 to 1: 3. An emulsion polymer composed of a shell material which is incompatible with the core material and the plasticizer, wherein the core material is (A) an alkyl acrylate having at least 3 carbon atoms in the alkyl group and / or Or 15 to 100% by weight of a methacrylic acid alkyl ester having at least 2 carbon atoms in the alkyl group and / or styrene and optionally (B) methyl acrylate or methyl methacrylate, up to 85% by weight of ethyl acrylate and (C ) Other radically polymerizable other monomers up to 20% by weight, the shell material being a methyl methacrylate homopolymer or At least 80 wt% is now configured, characterized in that it is a copolymer having a glass transition temperature above 50 ° C., plastisols based on methyl methacrylate copolymer is described.

[0006]

However, the known acrylic plastisols seen in the former proposal have a drawback that they have a poor pot life as compared with vinyl chloride resin-based plastisol compositions. It has the drawbacks of low fluidity and insufficient gelling performance after storage.

The plastisol found in the latter proposal is a plasticizer whose plasticizer does not swell the methyl methacrylate polymer, particularly dioctyl phthalate (DOP).
In addition to being limited to specific plasticizers such as, the core particles are limited to homopolymers or copolymers of (meth) acrylic acid ester having a long-chain alkyl group, resulting in mechanical There is a drawback that the characteristics tend to be insufficient.

Therefore, an object of the present invention is to maintain excellent fluidity required for coating, molding, etc. even during long-term storage, while exhibiting excellent gelling performance upon heating, and to provide a machine for gelling molded articles. Another object of the present invention is to provide an acrylic resin-based plastisol composition which is excellent in physical properties.

[0009]

According to the present invention, in a plastisol composition comprising a plasticizer for acrylic resin and acrylic resin particles dispersed in the plasticizer, the acrylic resin particles are (meth) It is characterized by comprising a core of a resin component mainly composed of an acrylic ester unit and a shell of a resin component having a polar group-containing monomer unit selected from the group consisting of an acid group, a salt group thereof, a hydroxyl group and an ether group. The plastisol composition having excellent pot life is provided.

The acrylic resin particles contain a polar group selected from the group consisting of an acid group, a salt group thereof, a hydroxyl group and an ether group at a concentration of 2 to 330 mmol / 100 g per particle weight. preferable.

In the plastisol composition of the present invention, the main plasticizer contained in the plasticizer in an amount of 60% by weight or more has a solubility index (SP value) in the range of 7.9 to 10.0. A certain plasticizer is preferable in terms of gelation performance.

[0012]

In the present invention, the acrylic resin particles dispersed in the plasticizer are composed of a core of a resin component mainly composed of a (meth) acrylic acid ester unit, an acid group, a salt group thereof, a hydroxyl group and an ether group. A remarkable feature is the use of acrylic resin particles composed of a shell of a resin component having a polar group-containing monomer unit selected from the group.

In the present invention, in this acrylic resin, the core of the resin component mainly composed of the (meth) acrylic acid ester unit is compatible with the plasticizer upon heating to give good gelling performance, while the polar The shell of the resin component containing the group-containing monomer unit prevents the acrylic resin and the plasticizer from being compatible with each other during storage at room temperature and extends the pot life.

Please refer to Tables 3 and 4 of Examples described later and the graph (FIG. 2) showing the relationship between the elapsed days and the viscosity of the acrylic resin plastisol. When the surface of the acrylic resin is formed of a resin mainly composed of a (meth) acrylic acid ester unit, like the center of the particle, the pot life is only about two days. When a shell of a resin containing a polar group-containing monomer unit is formed on the surface of a resin core of a (meth) acrylic acid ester unit, the pot life is 20 days or more, particularly 28 days.
It is extended more than a day. Moreover, this acrylic resin has a shell of resin containing a polar group-containing monomer unit formed on the surface thereof, but when it is heated to a temperature of about 150 ° C., a molded article having excellent toughness is easily obtained. To form.

In general, the solubility index (Solubility Par) is used as a standard for evaluating the compatibility of substances.
ameter, SP value) are widely used. This S
What is the P value? BRANDRUP etc. Hen Polymer
As defined in Chapter 4 of Handbook (1967), it is the 1/2 power value of the cohesive energy density and represents the degree of hydrogen bonding of a substance. When the degree of hydrogen bonding is large, a large value is obtained. take. As an example, in the case of polyethylene, 8.0 (cal / cm ³ ) ^1/2 , and in the case of polyacrylonitrile having a strong hydrogen bond, 15.4 (ca
1 / cm ³ ) ^1/2 .

The SP value of the vinyl chloride monomer is 7.8 (cal /
cm ³ ) ^1/2 , the hydrogen bondability is medium. Regarding compatibility with low molecular weight substances (plasticizers) of polyvinyl chloride (PVC), those having no hydrogen bonding property have an SP value of 8.5 to 1.
It is known that in the range of 1.1, it is compatible with the intermediate one having a hydrogen bonding property in the SP value range of 7.8 to 9.9. It is incompatible with anything that has a strong hydrogen bond.

On the other hand, the SP value of the methyl methacrylate (MMA) monomer is 8.8 (cal / cm ³ ) ^1/2 and the hydrogen bondability is moderate. Polymethylmethacrylate (PMM
Regarding the compatibility between A) and the low molecular weight substance (plasticizer), those having no hydrogen bonding property and those having a medium hydrogen bonding property in the range of SP 8.9 to 12.7 and SP 8.5 to 13. It is known that they are compatible in the range of 3. It is incompatible with anything that has a strong hydrogen bond.

Table 1 below shows the SP value, molecular weight and P of the plasticizer.
The compatibility with VC and PMMA (○ ×) is shown. Although used as plasticizers, the hydrogen bonding properties are all moderate. From Table A, as the plasticizer for acrylic resin,
It is understood that those having a relatively low molecular weight and a relatively high SP value are suitable.

[0019]

[Table 1]

A plasticizer that is compatible with PMMA and can easily form an elastomer by heat treatment has a relatively small molecular weight, and therefore easily penetrates into PMMA particles even at room temperature. Since the plasticizer penetrates into the particles and the particles swell, the storage stability deteriorates. It is also known that PVC cannot be used when it is combined with DBP or DEP having a large SP value and a small molecular weight, because the storage stability is extremely poor.

Another reason why the plastisol of PMMA has a shorter pot life than the plastisol of PVC is P
The specific gravity of PMMA is smaller than that of VC, and it is easy to allow the infiltration of the plasticizer. Specific gravity of PVC: 1.4 g / cc PMMA: 1.2 g / cc

It is known that when the alkyl chain of methacrylic acid ester is increased, it becomes compatible with a plasticizer having a small SP value. If the problem of pot life is only the molecular weight of the plasticizer, that is all that is required, but as the alkyl chain is made larger, the specific gravity becomes smaller, and the effects are offset. Enlarging the specific gravity of PMMA is technically difficult because PMMA is a class having a large specific gravity in the emulsion-polymerizable vinyl polymer.

According to the present invention, in view of the above-mentioned difficulties, on the surface of the core of a resin mainly composed of a (meth) acrylic acid ester unit, an acid group, a salt group thereof, a hydroxyl group and an ether group are formed. It has succeeded in improving the pot life of plastisol by a simple means of forming a shell of a resin having a polar group-containing monomer unit selected from the group consisting of:

In the present invention, the acrylic resin particles are acid groups,
The polar group selected from the group consisting of the salt group, hydroxyl group and ether group is 2 to 330 mmol / 1 per particle weight.
It is desirable to contain it at a concentration of 00 g. Table 3 described later
As shown in, when the concentration of the polar group is less than the above range, the pot life becomes lower than that in the above range, while when the concentration of the polar group exceeds the above range, the gelling performance is the above. It becomes lower than that in the range.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION In FIG. 1 for explaining the structure of acrylic resin particles used in the plastisol of the present invention,
This acrylic resin particle 1 is selected from the group consisting of a resin core 2 mainly composed of a (meth) acrylic acid ester unit and an acid group, a salt group thereof, a hydroxyl group and an ether group formed on the surface thereof. And a resin shell 3 having a polar group-containing monomer unit. The core 2 comprises emulsion polymerization of a monomer mainly composed of (meth) acrylic acid ester, seed polymerization,
Although it is produced by suspension polymerization, heterogeneous solution polymerization, or the like, the shell 3 may be integrally formed by these polymerization steps, or may be separately formed.

[Acrylic Resin] Examples of the ester of acrylic acid or methacrylic acid which is the main component of the core-forming resin component include methyl (meth) acrylate, ethyl (meth) acrylate, isopropyl (meth) acrylate, ( N-butyl (meth) acrylate, isobutyl (meth) acrylate, n-amyl (meth) acrylate, isoamyl (meth) acrylate, n-hexyl (meth) acrylate,
Examples include 2-ethylhexyl (meth) acrylate and n-octyl (meth) acrylate. However, the above (meta)
Acrylic acid means acrylic acid or methacrylic acid. The above (meth) acrylic acid esters may be used alone or in combination, and may be a copolymer with another monomer. The preferred ester is methyl methacrylate.

Other comonomers copolymerized with these monomers include styrene, vinyltoluene, acrylonitrile, methacrylonitrile, vinyl acetate, and (meth).
Examples thereof include acrylic acid glycidyl ester, (meth) acrylic acid hydroxypropyl ester, (meth) acrylic acid hydroxyethyl ester, (meth) acrylamide, and (meth) acrylic acid aminoethyl ester.

From the viewpoint of pot life and mechanical properties, the content of the (meth) acrylic acid ester unit in the core resin component is 50% by weight or more, particularly 7% by weight, based on the core resin component.
It is preferably present in an amount of 0% by weight or more.

The polar group-containing monomer unit present in the shell-forming resin component has an acid group, a salt group, a hydroxyl group or an ether group, and these are homopolymers, random copolymers and graft copolymers. It can exist in the form of a united block copolymer.

A chemical bond may be generated between the shell-forming resin component and the core-forming resin component, or a physical bond may be formed. From the viewpoint of stability, it is preferable that the shell-forming resin component and the core-forming resin component are chemically bonded by graft copolymerization, block copolymerization or the like, or at least molecules of polymer chains are entangled with each other.

The acid group-containing monomer unit in the shell-forming resin component is an anionic monomer unit such as a carboxylic acid, a sulfonic acid, a phosphonic acid or a salt thereof, and specific examples are as follows. To be Ethylenically unsaturated carboxylic acid or its anhydride; acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, maleic anhydride, itaconic anhydride and the like. Monomers having sulfonic acid groups; for example, styrene sulfonic acid, vinyl sulfonic acid, acrylic sulfonic acid, acrylamidomethylpropane sulfonic acid, acrylic sulfonic acid, methacryl sulfonic acid, acryl-2-ethyl sulfonic acid, methacryl-2-ethyl sulfonic acid, etc. .

These acid group-containing monomer units may be present in the form of metal salts such as sodium, potassium and calcium, ammonium salts, amine salts and the like.

Examples of the hydroxyl group-containing monomer unit include vinyl alcohol and allyl alcohol.

As the comonomer contained in the shell-forming resin component, the monomers exemplified for the core resin component, particularly acrylic monomers are used.

When the shell-forming resin component is a separately synthesized resin, as the resin, in addition to the homopolymers and copolymers of the polar group-containing monomers, resins generally referred to as water-soluble polymers, for example, Cellulose derivatives such as polyvinyl alcohol, methyl cellulose, ethyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, partially saponified polyvinyl acetate, polyvinyl methyl ether, polyacrylic acid, polymethacrylic acid, vinyl methyl ether / maleic anhydride copolymer Coalescence, polyvinylpyrrolidone, acrylamide / acrylate copolymer, partially saponified acrylamide / methylenebisacrylamide copolymer, saponified vinyl acetate / methyl acrylate copolymer, polyoxy Ethylene compounds, polystyrene sulfonic acid, poly-2-acrylamido-2-methylpropanesulfonic acid, and gelatin, modified casein, modified starch, sodium alginate, can also be used Torakantogomu like.

The ratio of the shell-forming resin component in the acrylic resin particles is such that the polar group selected from the group consisting of the above-mentioned acid group, salt group, hydroxyl group or ether group is
It may be contained at a concentration of 2 to 330 mmol / 100 g, particularly 3.5 to 220 mmol / 100 g per particle weight. The shell resin component of the preferred acrylic resin particles is an anionic group, especially of the formula In the formula, R ₁ is a hydrogen atom or an alkyl group having 4 or less carbon atoms, X is a hydrogen atom or a cation, and n is a valence of the cation. It is made of an acrylic resin having a unit represented by

If the content ratio of the polar group-containing monomer unit in the resin component for shell formation is high, the thickness of the resin component for shell formation, that is, the ratio per the whole particles can be decreased, and therefore, the adverse effect of the polar group on the gelling performance is adversely affected. Is less.
In this sense, the shell-forming resin component preferably comprises a homopolymer or homopolymer block of a polar group-containing monomer, and in the case of a copolymer or copolymer block, the content of the polar group-containing monomer unit is
It is preferably 10% by weight or more, and particularly preferably 30% by weight or more.

Among the acrylic resin particles, at least the core-forming resin component should have a molecular weight sufficient to form a tough film, and generally has a molecular weight of 100,000 or more, particularly 200,000 or more. desirable. The acrylic resin particles have a median particle diameter (median diameter) of 0.1 to 0.1.
The thickness is preferably 20 μm, particularly 0.3 to 10 μm. By using a value obtained by multiplying the number of millimoles of carboxylic acid per 100 g of resin by the particle size (number of μm), it is useful to provide a plastisol having a well-balanced pot life and gelling performance, regardless of the particle size. It was found that the conditions for resin particles can be specified. The value obtained by multiplying the number of millimoles of carboxylic acid per 100 g of resin by the particle size (number of μm) is B
When expressed as F, in order to obtain a plastisol having excellent pot life and gelling performance, the BF of the resin particles is preferably in the range of 2 <BF <200, more preferably 7 <
Adjusting to a range of BF <150 gives very good results.

[Production of Acrylic Resin] Acrylic resin particles used in the present invention are obtained by emulsion polymerization, suspension polymerization, heterogeneous solution polymerization, seed polymerization, etc. of a monomer mainly composed of (meth) acrylic acid ester. Polymerize to make a core and then form a shell. The core particles are generally produced by emulsifying or suspending each of the above components as an oil phase in water and emulsion polymerization or suspension polymerization in the presence of a polymerization initiator. The aqueous medium is preferably used in an amount of 0.6 to 4 times by weight, particularly 1 to 2.3 times by weight, based on the total amount of the above monomer components.

In the emulsion polymerization, the dispersion particle size of the monomer in water is controlled to an emulsion particle size, generally 0.05 to 0.2 μm, by a surfactant, particularly an anionic surfactant or a nonionic surfactant. And polymerize. The amount of the surfactant used is appropriately 0 to 5 parts by weight based on 100 parts by weight of the monomer component.

At the time of suspension polymerization, it is preferable to adjust the particle size of the dispersed phase in the range of 1 to 20 μm by using an ordinary suspension stabilizer. Examples of the suspension stabilizer include water-soluble polymers, poorly water-soluble powdered inorganic compounds, surfactants and the like known in the art. Examples of the water-soluble polymer include gelatin, tragacanth gum, starch, methyl cellulose, carboxymethyl cellulose, polyvinyl alcohol, polyacrylic acid salts and the like. Examples of the inorganic compound include barium sulfate, calcium sulfate, barium carbonate, calcium carbonate, magnesium carbonate, calcium phosphate, talc, bentonite, kensou soil, clay and the like. The amount of the suspension stabilizer used is usually 0.1 to 5 parts by weight per 100 parts by weight of the suspended particles.

The emulsification or suspension of the oil phase in the above-mentioned emulsion or suspension polymerization method can also be carried out by a usual low and medium shear stirrer.
In addition, the core particles can be adjusted to a particle size according to the purpose by using a high shear stirrer such as a homomixer or a homogenizer.

As the polymerization initiator, in the case of suspension polymerization, for example, azobisisobutyronitrile, 2,2'-azobis (2-methylbutyronitrile), 2,2'-azobis (2,4-dimethyl). Azo compounds such as valeronitrile),
Cumene hydroperoxide, dicumyl peroxide, t
-Oil-soluble initiators such as butyl hydroperoxide, di-t-butyl peroxide, benzoyl peroxide, and peroxides such as lauroyl peroxide are used, and in the case of emulsion polymerization, for example, hydrogen peroxide solution, potassium persulfate, Water-soluble initiators such as ammonium persulfate, azobiscyanovaleric acid, azobisisobutylamidine hydrochloride are used. Further, the peroxide type initiator can be used as a redox type low temperature initiator in combination with a suitable reducing agent. In addition to these, a combination of ionizing radiation such as γ-ray or accelerated electron beam or ultraviolet ray and various sensitizers can be used. The polymerization initiator is preferably used in an amount of 0.5 to 10 parts by weight per 100 parts by weight of the monomer. The polymerization is usually carried out in an inert atmosphere such as nitrogen at a temperature of 50 to 100 ° C. for about 2 to 12 hours.

The core particles can also be produced by heterogeneous solution polymerization. In this polymerization method, a solvent that dissolves the monomer but not the produced polymer is used, the monomer is dissolved in the solvent, and the polymerization is performed in the presence of a polymerization initiator. In this case, as the polymerization proceeds, particle growth of the produced polymer occurs, and desired core particles are obtained.

The particle size of the core particles can be adjusted by seed polymerization. For example, resin particles obtained by emulsion polymerization can be dispersed in an aqueous medium, a monomer and an initiator can be added, and polymerization on the surface of seed particles can be performed.

In order to form a shell having a carboxyl group, a hydroxyl group or other polar groups on the surface of the core particle, the following means are adopted.

(1) Saponification Method If acrylic acid ester, methacrylic acid ester, or vinyl acetate is present in at least the outermost shell, the particles are polymerized in water (emulsion polymerization, seed polymerization, suspension polymerization) and then hydroxylated. By heating in the presence of a strong alkali such as sodium to hydrolyze or saponify the ester,
A carboxyl group or a hydroxyl group can be easily introduced on the outermost surface of the particles. Since the thickness of the material layer incompatible with the plasticizer can be minimized, the influence on the physical properties of the gel can be minimized.

(2) Emulsion and Seed Polymerization Method It is difficult to polymerize a water-soluble monomer such as acrylic acid or methacrylic acid and introduce it into particles by ordinary underwater polymerization. By making the anionic monomer acidic and making the cationic monomer alkaline, and by adding a non-solvent for these monomers, the water solubility of the monomers is reduced, and they are fixed on the particle surface to allow polymerization. It can be done. It is also possible to make the outermost layer rich in polar monomers by devising a monomer feed, that is, by adding a polar monomer in the polymerization system in a single step or multiple steps together with an initiator as needed during the polymerization. is there. In emulsion polymerization, the polar monomer tends to gather in the outermost shell and the hydrophobic monomer tends to gather in the inner shell, so that it is relatively easy to control the core / shell structure. The polymerization conditions may be those already mentioned.

(3) Soap-Free Emulsion Polymerization Using Water-Soluble Polymer Separately, even if it is not soap-free polymerization, if a water-soluble polymer is used as a protective colloid, the particle surface is a polar component of the water-soluble polymer attached to it. To be covered.

(4) Blending of Water-Soluble Polymer and Particles After particles are formed by polymerization in water, the water-soluble polymer is simply blended and dried to produce particles having a polar component attached to the surface.

[Plastisol composition] The plastisol composition of the present invention comprises a plasticizer for acrylic resin and surface-polarized acrylic resin particles dispersed in the plasticizer.
Examples of the plasticizer include aromatic dibasic acid to polybasic acid esters such as phthalic acid; aliphatic dibasic acid to polybasic acid esters; phosphoric acid esters; hydroxy polyvalent carboxylic acid esters; fatty acid esters; Polyhydric alcohol ester;
Alternatively, among epoxidized oils, those suitable for acrylic resin are used.

Suitable plasticizers are those in which the main plasticizer contained in the plasticizer in an amount of 60% by weight or more has a molecular weight of 220 to 4
20 and a solubility index (SP value) of 7.9 to 1
It is in the range of 0.0. Examples of the aromatic acid that constitutes the plasticizer include phthalic acid, and examples of the aliphatic carboxylic acid include:
Examples thereof include adipic acid, azelaic acid, sebacic acid, and the like, and examples of the hydroxycarboxylic acid include glycolic acid. As the alkyl group in the ester, ethyl,
Lower alkyl groups such as propyl and butyl are used, and those having a higher alkyl group such as isodecyl group, octyl group (ethylhexyl group) or aralkyl group such as benzyl group and cresyl group are also used as long as the above molecular weight is satisfied. To be done.

Specifically, diethyl phthalate, dibutyl phthalate, butylbenzyl phthalate, acetyltributyl citrate, butylphthalyl glycolate, dioctyl adipate and the like are suitable plasticizers.

The weight ratio of the acrylic resin particles and the plasticizer is such that sufficient fluidity can be obtained during coating and molding and sufficient physical properties can be obtained during gelling. It is preferably in the range of 1 to 5: 6, especially 5: 3 to 1: 1. In this plastisol, a resin compound known per se, for example, a filler, a colorant, a heat stabilizer, a foaming agent, a cross-linking agent, an antioxidant, a thickener, a thinning agent, an oxygen absorber, etc. is itself added. It can be blended according to a known formulation.

[Use] Since the acrylic resin plastisol composition of the present invention has an excellent pot life and excellent gelling performance, various uses in which PVC plastisol has been widely used, for example, packing. Moreover, it can be widely used for forming or coating gaskets, interior parts, toys, daily necessities, miscellaneous goods, various coatings, various backings, films or sheets, etc.

For the molding, means such as slush molding, rotational molding, casting, dip molding and the like can be used, and for coating, spread method, depping method, spin coating method, gravure coating method, spray coating method, A screen coating method or the like is adopted. INDUSTRIAL APPLICABILITY The acrylic resin plastisol of the present invention is particularly useful for nozzle-lining a gasket or liner for sealing various containers or container lids.

Generally, the acrylic resin plastisol composition of the present invention preferably has a viscosity of 0.4 to 1000 poise at room temperature from the viewpoint of workability during coating and molding,
On the other hand, the hardness at the time of gelation varies depending on the application, but it is 1 for the applications such as the above-mentioned sealing gasket or liner.
It preferably has a hardness (JIS-A) of 5 to 75. The plastisol can be easily cured by heating it to a temperature of 100 to 230 ° C.

[0058]

The present invention will be further described in the following examples. Abbreviations in the examples are as shown in Table 2 below.

[0059]

[Table 2]

Example 1 Preparation of seed particles Distilled water 840 was placed in a reaction vessel equipped with a stirrer and a cooling tube.
g, sodium dodecylbenzene sulfonate (emulsifier)
0.28 g, potassium perisoisosulfate (initiator) 0.
12 g, and methyl methacrylate monomer (MMA) 6
0 g was charged and the temperature was raised to 80 ° C. with stirring. 80 ° C
After being held for 1 hour, 54 g of distilled water, 2.4 g of an emulsifier, 1. Initiator were added together with 1/6 amount of 540 g (A) of MMA.
2 g and 1/6 amount of the mixture (B) of 0.54 g of sodium hydrogen carbonate were added and the reaction was continued. The addition of 1/6 amount of A and B was repeated every 20 minutes after the first addition, and after the final addition, the reaction was completed by holding at 80 ° C. for another hour. After cooling, the mixture was filtered through a filter cloth to obtain a dispersion liquid (C) having a solid content of 39%. The dispersion liquid (C) was used as a seed, and thereafter seed polymerization was performed to adjust the particle size of the dispersion particles.

Seed Polymerization 1 100 ml of distilled water was placed in a reaction vessel equipped with a stirrer and a cooling tube.
0 g, 59 g of the dispersion liquid (C) and 23 g of MMA were charged,
The temperature was raised to 80 ° C. with stirring. After reaching 80 ° C., 0.
An initiator aqueous solution of 2 g / 20 g of distilled water was added to start the reaction. After 20 minutes from the addition of the initiator, the first addition of MMA 45 g was performed to allow the polymer particles to absorb the monomer in 10 minutes, and further 51 g of distilled water and 0.75 g of an emulsifier,
A 1/15 amount of a mixture (D) of 1.5 g of an initiator and 0.75 g of sodium hydrogen carbonate was added, and the mixture was kept for 20 minutes. After the second addition of the monomer, MMA45 × 2 (n-1) g, 2 (n-1) / (M) of the mixture (D) was added to the nth addition.
The addition of 15 amounts was performed according to the first addition method. 0.20 g / 20 1 hour after the 4th addition
An initiator aqueous solution of g distilled water was added, and the reaction was completed by holding it for 2 hours. By this series of operations, solid content 3
A 9% PMMA dispersion (E) was obtained.

Seed Polymerization 2 Using the dispersion liquid (E) in place of the dispersion liquid (C) and using 0.30 g of the emulsifier in place of 0.75 g of the emulsifier, the same operation as in seed polymerization 1 was carried out to obtain PMMA dispersed particles. The particle size was adjusted. By this operation, a PMMA dispersion liquid (F) having a solid content of 39% and a particle size of 2 μm was obtained.

Preparation of Core / Shell Particles A reaction vessel equipped with a stirrer and a cooling tube was charged with 1200 g of the dispersion (F) and 18.7 g of sodium hydroxide,
The temperature was raised to 95 ° C with stirring. The temperature was kept at 95 ° C. for 5 hours to hydrolyze the surface layer of PMMA particles to obtain a dispersion (G) in which a carboxylic acid component was introduced into the surface layer of the particles. To 600 g of the half amount of the dispersion liquid (G), 120 g of a 7% hydrochloric acid aqueous solution was added to neutralize the excess sodium hydroxide, and at the same time, the sodium salt of the carboxylic acid on the surface layer of the particles was replaced with the acid form.
The obtained dispersion is suction-filtered, the filtered solid matter is washed with water and kept in a hot air circulation type oven at 80 ° C. for 10 hours, and then further kept in a vacuum dryer at 80 ° C. for 2 days and nights. The water was completely evaporated. The partially agglomerated solid was crushed by a rotary ball mill for 8 hours, and the mesh No. After passing through a No. 32 sieve, 200 g of fine particle powder (H) having an MMA component as a core and an MAA component as a shell was obtained.

Preparation of plastisol 40 g of powder (H) and 36 g of plasticizer BPBG in a mortar
Was weighed and kneaded with a pestle to prepare a uniform paste (I). Defoam in a vacuum dryer to obtain paste (I) 7
0 g was placed in a transparent sample bottle and stored at 25 ° C.

Evaluation of pot life The pot life was evaluated based on the viscosity measurement data. A B-type viscometer was used for viscosity measurement, and No. 4 rotors,
It carried out on the conditions of 6 rotations and 25 degreeC. The number of days of storage when the viscosity value exceeded 1000 poises was used as a measure of pot life. In order to produce a practically useful plastisol, the pot life here is preferably 20 days or longer. Viscosity was measured for up to 4 weeks, and if the viscosity did not reach 1000 poise after 4 weeks, the pot life was indicated as> 28. The evaluation results are shown in Table 3 together with the results of other examples and comparative examples.

Evaluation of Gelation Performance A plastisol having a sufficiently long pot life and capable of being stably used for a long period of time is useful, and also has a gelation performance of being capable of forming a flexible and tough gel-like substance by heat treatment for a short time. It is very important from the standpoint of plastisol availability. An excellent plastisol can be called only when the pot life and gelling performance are well balanced.

The gelling performance was evaluated by determining the properties when 5 g of the paste (I) was placed in an aluminum pan and heat-treated at 150 ° C. for 5 minutes. When the sheet was a flexible and tough sheet, it was indicated by ◯, when it was a flexible sheet but the strength was slightly inferior, it was indicated by Δ, and when it was a waxy brittle solid substance or when it was not a flexible sheet, it was indicated by x. The evaluation results are summarized in Table 3.

[0068]

[Table 3]

[Examples 2 to 5] Powder (H) 4 of Example 1
0 g, ATBC, DEP, DBP, as a plasticizer
And 36 g of BBP, respectively, and the paste-like materials of Examples 2 to 5 were prepared in the same manner as in Example 1. Table 3 also shows the evaluation results of the pot life and gelation performance of Examples 2 to 5.

Comparative Examples 1 to 5 Using 600 g of the dispersion (F) prepared in Example 1, 220 g of dry powder was prepared without alkali hydrolysis. 40 g of the dry powder prepared here and 36 g of the plasticizer corresponding to Examples 1 to 5
The paste-like materials of Comparative Examples 1 to 5 were prepared in combination with and the pot life and gelling performance were evaluated. The results are shown in Table 3.

[Examples 1a to 5a] Using 600 g of the dispersion (G) of Example 1 and drying without neutralization with hydrochloric acid, the MMA component was used as the core and the sodium salt component of MAA was used as the shell. Core / shell particle powder 230
g was adjusted. Core / shell particle powder 4 prepared here
0 g and 36 g of the plasticizer corresponding to Examples 1 to 5 and Comparative Examples 1 to 5 were combined to prepare the paste-like materials of Examples 1a to 5a. The evaluation results of pot life and gelling performance are shown in Table 3.

In the above examples, examination was made on the method of introducing a shell portion composed of a carboxylic acid and a carboxylic acid salt into an MMA homopolymer by alkaline hydrolysis, and the balance between the pot life extension effect and the gelling performance. The results are shown. In Examples 6-12 and Comparative Examples 6-12 below,
The same investigations as in Examples 1 to 5 and Comparative Examples 1 to 5 were carried out on the copolymers.

[Examples 6 to 12 and Comparative Examples 6 to 12] In Examples 6 to 12, in the polymerization method of Example 1, a monomer mixture containing (meth) acrylic acid ester as a main component was used in place of MMA. In the case of using the prepared acrylic copolymer particles, mixing the particle powder core / shell-formed by alkali hydrolysis and the plasticizer at a ratio of 10: 9 to form a paste,
The examination results of pot life and gelation performance will be described. The composition of the copolymer particles, the type of plasticizer used, and the evaluation results are summarized in Table 4.

[0074]

[Table 4]

Comparative Examples 6 to 12 are Examples 6 to 12, respectively.
12 shows the examination results in the case where there is no shell portion corresponding to No. 12, and the details of the results are shown in Table 4.

[Comparative Examples X-1, X-2, Y-1, Y-
2] Comparative Examples X-1, X-2, Y-1, and Y-2 are examination examples in the case of using copolymer particles not mainly containing (meth) acrylic acid ester. The details of the results are summarized in Table 4.

Mainly composed of a core portion mainly composed of a (meth) acrylic acid ester polymer compatible with a plasticizer, and a component having an acid group and a salt group thereof incompatible with almost all plasticizers. The amount of the acid component in the resin component is a very important factor because the resin particles composed of the configured shell portion are used to provide a plastisol having a well-balanced pot life and gelling performance. . If the amount of the acid component in the resin component is small, the pot life will be too short to withstand use, and if the amount of the acid component is large, it will be difficult to be compatible with the plasticizer, resulting in poor gelling performance. Moreover, gelation becomes impossible.

The following examples and comparative examples explain the optimum amount of the acid component for providing a plastisol having a well-balanced pot life and gelling performance.

[Examples 13-18, Comparative Examples 13-18]
According to the method of Example 1, MMA / EG having different particle sizes
An MMA copolymer (MMA / EGMMA = 98/12) particle dispersion was prepared. The particle size of these dispersed particles is 0.6 in the particle size measured by Microtrac.
It was found to be μm, 1.3 μm, and 2.0 μm. Each of these three types of MMA / EGMMA copolymer dispersions was saponified under four different alkaline hydrolysis conditions to prepare a particle dispersion in which the amount of carboxylic acid introduced into the particle surface layer was variously adjusted. did. The resulting dispersion was neutralized with a dilute aqueous hydrochloric acid solution, and then acidified with hydrochloric acid to settle the particles, and then the solid matter was collected by filtration and dried without acid washing with hydrochloric acid. The obtained partial agglomerates were pulverized with a rotary ball mill to prepare 12 kinds of fine particle powders having different particle diameters and carboxylic acid amounts. Each fine particle powder and BPBP were mixed at a ratio of 10: 9 to prepare a paste-like material, and pot life and gelling performance were evaluated. The details of the fine particle powder and the evaluation results are summarized in Table 5. The hydrolysis conditions were adjusted by the reaction temperature, the time, and the amount of alkali, and the conditions 1 → 4 in Table 5 were adjusted so that the hydrolysis would proceed further.

Determination of the amount of carboxylic acid The amount of carboxylic acid with respect to the resin content was determined by IR measurement. In the usual IR measurement, when the amount of carboxylic acid with respect to the resin component is small, the absorption of the MMA component is large,
Since the accuracy of quantification of carboxylic acid is significantly impaired, quantification of carboxylic acid was performed by the diffuse reflection method. By using the diffuse reflection method, it is possible to selectively retrieve information in the vicinity of the surface layer of the particle, and it is possible to quantify the minute amount of carboxylic acid on the surface layer of the particle without being obstructed by absorption in the central part of the particle. It was The KBr powder and the resin powder were mixed at a ratio of 95: 5, and IR measurement was performed. The amount of carboxylic acid was expressed by the number of millimoles of the carboxylic acid component per 100 g of resin.

[0081]

[Table 5]

From the results in Table 5, it was found that the range of the amount of carboxylic acid required to balance the plastisol pot life and gelling performance was largely dependent on the particle size. It was found that the smaller the particle size, the more the carboxylic acid component needs to be introduced in order to balance the pot life and the gelling performance. It was difficult to specify the conditions of the resin particles that give a plastisol excellent in pot life and gelation performance, only by the amount of introduced carboxylic acid.

As a result of various studies, by using a value obtained by multiplying the number of millimoles of carboxylic acid per 100 g of resin by the particle size (number of μm), the pot life and the gelling performance were well balanced regardless of the particle size. It has been found that the conditions of resin particles useful for providing plastisols can be defined. When the value obtained by multiplying the number of millimoles of carboxylic acid per 100 g of resin by the particle size (number of μm) is expressed as BF, in order to obtain plastisol having excellent pot life and gelling performance, the BF of the resin particles is preferably 2 Adjusting to a range <BF <200, more preferably 7 <BF <150 gives very good results.

[Comparative Examples 19 to 22] According to the polymerization method of Example 1, MMA-MAA copolymer particle dispersions were prepared with four types of MAA contents, and the carboxylic acid component was introduced into the particles at the polymerization stage. Tried. The prepared MMA-MAA copolymer particle powder and BPBG were mixed at a ratio of 10: 9 to prepare plastisol pastes of Comparative Examples 19 to 22. Comparative Example 19 has MMA / MAA = 98/2, Comparative Example 20 has MMA / MAA = 94/4, and Comparative Example 21 has MMA / M.
AA = 90/10, MMA / MAA = 8 in Comparative Example 22
Resin particles having a copolymerization composition of 0/20 were used. The evaluation results of pot life and gelling performance are shown in Table 6. In any case, plastisol having a well-balanced pot life and gelling performance was not obtained.

Both normal IR measurement for solidifying and measuring a mixture of KBr and resin powder and IR measurement by diffuse reflection were carried out on the resin powders of Comparative Examples 19 to 22. No significant difference could be found in the intensity ratio of carboxylic acid absorption. That is, since the composition of the entire particle found by the usual IR measurement and the composition of the surface layer of the particle found by the diffuse reflection method are the same, the particles of Comparative Examples 19 to 22 have a uniform composition and have a core / shell structure. I knew it wasn't.

[0086]

[Table 6]

Example 19 Resin particles were prepared by the same procedure and material composition as before the fourth addition of the monomer in the seed polymerization 2 in the polymerization method shown in Example 1. Attempts were made to adjust the core / shell particles by changing the fourth monomer addition procedure and composition. First, MMA180
g, a mixed solution of an initiator, an emulsifier, and the like, which are commensurate with the amount of the monomer, were sequentially added, and after the polymerization was continued, the final addition of the monomer mixture of MMA and MAA was performed. As the procedure of addition,
The addition of 60 g of the monomer mixture and the addition of the mixed solution such as the initiator and the emulsifier were repeated 3 times, and the MMA / MAA ratio was changed to 9
It was changed to / 1, 8/2, 7/3. The obtained dispersion was acidified with hydrochloric acid, and then the solid substance was collected by filtration. Thereafter, a dry powder was prepared according to Example 1.

When IR measurement of the obtained powder was carried out, a clear difference was found between the data by the conventional method and the data by the diffuse reflection method. The absorption intensity of the carboxylic acid / carboxylic acid ester by the diffuse reflection method was clearly higher than the absorption intensity ratio by the conventional method, and it was confirmed that the particles were core / shell particles. The BF value was 75 from the measurement data by IR diffuse reflection method and the particle size measurement.

100 parts of dry powder was combined with 90 parts of BPBG to prepare a plastisol paste, and pot life and gelling performance were evaluated. As a result, the pot life was 4 weeks or longer, and a flexible and tough gel-like material was obtained by heat treatment at 150 ° C. for 5 minutes.

[Embodiment 20] MMA / AA (= 96 /
100 parts by weight of the monomer mixture of 4) was emulsified and seed polymerized to prepare a dispersion liquid having a particle diameter of 1.0 μm. To this dispersion was added 2 parts by weight of polyacrylic acid (Aldrich, weight average molecular weight 5000) in the form of an aqueous solution, and the mixture was uniformly mixed and then spray-dried to give a secondary particle size of 1
A dry powder of 0 μm was prepared. 100 parts by weight of dry powder and 80 parts of ATBC were mixed and adjusted to a paste, and then pot life and gelling performance were evaluated. As a result, the pot life was 4 weeks or more, and a flexible and tough gel-like material was obtained by heat treatment at 180 ° C. for 3 minutes. The JIS-A hardness was 65.

[Embodiment 21] MMA / AA (= 96 /
100 parts by weight of the monomer mixture of 4) was emulsified and seed polymerized to prepare a dispersion liquid having a particle diameter of 1.0 μm. To this dispersion, 2 parts by weight of polyvinyl alcohol (Aldrich, weight average molecular weight 16,000, 98% saponified product) was added in the form of an aqueous solution, and the mixture was uniformly mixed and spray-dried to give a secondary particle diameter of 10 μm. A dry powder was prepared. After 100 parts by weight of dry powder and 80 parts of BPBG were mixed and adjusted to a paste form, the pot life and gelling performance were evaluated, and the pot life was 4 weeks or longer, and 200
A soft and tough gel-like material was obtained under the heat treatment condition of ℃ -2 minutes. The JIS-A hardness was 60.

[Embodiment 22] MMA / AA (= 96 /
100 parts by weight of the monomer mixture of 4) was emulsified and seed polymerized to prepare a dispersion liquid having a particle diameter of 1.0 μm. To this dispersion, 2 parts by weight of polyethylene glycol (Aldrich, weight average molecular weight 10,000) was added in the form of an aqueous solution, uniformly mixed and then spray-dried to prepare a dry powder having a secondary particle diameter of 12 μm. After mixing 100 parts by weight of dry powder and 90 parts of ATBC and adjusting to a paste form, the pot life and gelling performance were evaluated. A tough gel-like product was obtained. Incidentally, JIS
-A hardness was 40.

[Example 23] PMM manufactured by Nippon Zeon Co., Ltd.
A particle powder R20 (molecular weight 300,000, particle diameter 1.0 μm)
Is dispersed in water, alkali hydrolysis is performed, and finally B
A particle powder having an F value of 50 was prepared. 100 parts of powder and 80 parts of plasticizer ATBC were mixed to prepare a plastisol paste, and pot life and gelling performance were evaluated. The pot life was 21 days, and a soft and tough gel-like material was obtained by heat treatment at 200 ° C. for 2 minutes.

[Example 24] PMM manufactured by Nippon Zeon Co., Ltd.
A particle powder F320 (molecular weight 2,000,000, particle diameter 1.5μ
m) was dispersed in water and subjected to alkaline hydrolysis to finally prepare a particle powder having a BF value of 32. 100 parts of powder and 80 parts of plasticizer ATBC were mixed to prepare a plastisol paste, and pot life and gelling performance were evaluated. The pot life was 25 days, and a flexible and tough gel-like material was obtained by heat treatment at 150 ° C. for 5 minutes.

[Comparative Example 23] PMM manufactured by Nippon Zeon Co., Ltd.
A particle powder R103 (molecular weight 2,000,000, particle diameter 30μ
m) was dispersed in water and subjected to alkaline hydrolysis to finally prepare a particle powder having a BF value of 90. 100 parts of powder and 80 parts of plasticizer ATBC are mixed to prepare a paste,
The pot life and gelling performance were evaluated. Although the pot life was 4 weeks or longer, a useful gel-like material having flexibility and toughness could not be obtained even when various heat treatment conditions were changed.

[Example 25] 80 parts of the powder of Example 24, 20 parts of the powder of Comparative Example 23, and 80 parts of ATBC were mixed to prepare a paste, and the pot life was 4
For a week or more, a flexible and tough gel-like material was obtained under the heat treatment condition of 130 ° C. for 5 minutes.

[Example 26] To 100 parts of a powder prepared in the same manner as in Example 1, 50 parts of ATBC (SP: 9.4, molecular weight: 402) and DIDP (SP: 7.2, molecular weight: 447) were added. 30 parts were combined and made into a paste. The pot life was 4 weeks or more, and a flexible and tough gel-like substance was obtained under the heat treatment condition of 150 ° C. for 5 minutes.

COMPARATIVE EXAMPLE 24 100 parts of the powder prepared in the same manner as in Example 1 was combined with 80 parts of DIDP to form a paste. The pot life was 4 weeks or more, but no useful gel-like substance was obtained even if various heat treatment conditions were changed.

[Comparative Example 25] For 100 parts of the powder prepared in the same manner as in Example 1, 25 parts of ATBC and DIDP2 were added.
5 parts were combined to form a paste. The pot life was 4 weeks or more, but no useful gel-like substance was obtained even if various heat treatment conditions were changed.

Example 27 To 100 parts of the powder prepared in the same manner as in Example 1, 60 parts of ATBC and 20 parts of ESO (molecular weight: about 1000) were combined to form a paste. The pot life was 4 weeks or more, and a flexible and tough gel-like material was obtained under the heat treatment condition of 180 ° C. for 5 minutes.

[0101]

According to the present invention, as the acrylic resin particles dispersed in the plasticizer, the core of the resin component mainly composed of the (meth) acrylic acid ester unit, the acid group and the salt group thereof,
By using particles of an acrylic resin composed of a shell of a resin component having a polar group-containing monomer unit selected from the group consisting of a hydroxyl group and an ether group, the pot life of plastisol is extended and gelation performance is also improved. be able to.

In the present invention, in this acrylic resin, the core of the resin component mainly composed of the (meth) acrylic acid ester unit is compatible with the plasticizer upon heating to give a good gelling performance, while The shell of the resin component containing the group-containing monomer unit can prevent the acrylic resin and the plasticizer from being compatible with each other during storage at room temperature and can extend the pot life.

The acrylic resin plastisols have various performances comparable to those of vinyl chloride homopolymers and copolymer plastisols. In addition, when incinerated, the release of hydrogen chloride into the atmosphere and the generation of dioxins are prevented, which is a great environmental advantage.

[Brief description of drawings]

FIG. 1 is an explanatory diagram for explaining a structure of acrylic resin particles used in a plastisol of the present invention.

FIG. 2 is a graph showing the relationship between the number of days elapsed and the viscosity of acrylic resin plastisols.

[Explanation of symbols]

 1 Acrylic Resin Particles 2 Acrylic Resin Core 3 Polar Group-Containing Resin Shell

Claims (5)

[Claims] 1. A plastisol composition comprising an acrylic resin plasticizer and acrylic resin particles dispersed in the plasticizer, wherein the acrylic resin particles are mainly composed of a (meth) acrylic acid ester unit. With the core of
A plastisol composition excellent in pot life, comprising a shell of a resin component having a polar group-containing monomer unit selected from the group consisting of an acid group, a salt group thereof, a hydroxyl group and an ether group. 2. The acrylic resin particles contain a polar group selected from the group consisting of an acid group, a salt group thereof, a hydroxyl group and an ether group in an amount of 2 to 330 mmol / 100 g per particle weight.
The plastisol composition according to claim 1, which is contained at a concentration of. 3. The shell resin component of the acrylic resin particles has the formula: In the formula, R ₁ is a hydrogen atom or an alkyl group having 4 or less carbon atoms, X is a hydrogen atom or a cation, and n is a valence of the cation. The plastisol composition according to claim 1, which comprises an acrylic resin having a unit represented by: 4. When the value obtained by multiplying the number of millimoles of carboxylic acid per 100 g of resin by the particle size (number of μm) is BF,
The plastisol composition according to claim 1, wherein the acrylic resin particles are composed of acrylic resin particles having a BF value in the range of 2 <BF <200. 5. The main plasticizer contained in the plasticizer in an amount of 60% by weight or more has a molecular weight of 220 to 420 and a solubility index (SP value) in the range of 7.9 to 10.0. The plastisol composition according to claim 1, which is a plasticizer.