JPH02202959A - Antistatic coating composition - Google Patents

Abstract

PURPOSE:To prepare an antistatic coating compsn. curable at room temp. and having an adjustable curing time by homogeneously dispersing a conductive filler in a specific curable compsn. CONSTITUTION:2-300 pts.wt. conductive filler (e.g. conductive carbon) is homogeneously dispersed in 100 pts.wt. curable compsn. which comprises at least one radical-curable oligomer selected from the group consisting of an unsatd. polyester, epoxy acrylate, urethane acrylate and polyene polythiol and, if necessary 200 pts.wt. or less (based on 100 pts.wt. said oligomer) polymerizable (meth) acrylic monomer (e.g. trimethylolpropane triacrylate).

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention relates to antistatic coating compositions for plastics, particularly antistatic coating compositions for polystyrene foams. Polystyrene foams that are antistatic by coating are useful as packaging materials for foodstuffs, precision equipment, electronic parts, etc., which do not want dirt and dust, and IC packaging materials, which do not want to be charged with static electricity.

[Conventional technology and issues]

Polystyrene foam is widely used as a packaging material for various products due to its light weight, heat insulating properties, inertia, and ease of molding. was there. On the other hand, it has been widely practiced to prevent static electricity by mixing paint resin (with conductive filler) and applying it to prevent static electricity. There is a solvent-free type, and since the solvent type requires the solvent to scatter during use, the solvent-free type is preferred from a safety and hygiene perspective1.
Typical solvent-free paints include epoxy resins and unsaturated polyester resins.

However, these conventional antistatic coatings are not necessarily satisfactory when applied to polystyrene foams. That is, polystyrene foams may deform when the temperature exceeds 50° C., and may also become deformed when dissolved in certain monomers such as styrene.

For this reason, coating resins need to be cured at room temperature.

However, in the case of epoxy resins that cure at room temperature, the pot life is determined by the formulation, which is difficult to adjust, and the working time is affected by the temperature, which has the disadvantage of poor work efficiency.On the other hand, unsaturated polyester resins The curing time can be adjusted by changing the amounts of the agent and accelerator, so the work efficiency is excellent, but since a styrene monomer is used as the crosslinking agent, there is a drawback that the polystyrene foam is melted and deformed.

[Means to solve the problem]

The present inventors have achieved the present invention as a result of intensive research aimed at improving the drawbacks of the prior art.

That is, the present invention provides at least one radically curable oligomer selected from the group consisting of unsaturated polyester, epoxy acrylate, urethane acrylate, and polyene polythiol, and optionally (meth) based on 100 parts by weight of the oligomer. 2 to 300 parts by weight of a conductive filler per 100 parts by weight of a curable composition obtained by adding 2001 parts or less of an acrylate polymerizable monomer.
This is an antistatic coating composition characterized in that parts by weight are uniformly dispersed.

The composition of the present invention can be cured at room temperature, and like unsaturated polyester resins, the curing time can be adjusted by changing the amounts of the curing agent and accelerator, thereby improving work efficiency. Furthermore, since it does not contain styrene monomer, it has the characteristic of not dissolving and deforming the polystyrene foam.

Of course, it can also be used for coating molded products of other thermoplastic resins and thermosetting resins.

The present invention will be explained in detail below.

The conductive filler used in the present invention is not particularly limited, and examples thereof include metal powders or metal fibers such as silver, aluminum, tin, nickel, and copper, carbon black, carbon fibers, and mixtures thereof.

The radically curable oligomers used in the present invention are selected from unsaturated polyesters, epoxy acrylates, urethane acrylates and polyene polythiols.

The unsaturated polyester that can be used in the present invention is not particularly limited, and may be one synthesized from an organic polybasic acid and a polyhydric alcohol, or a modified product thereof. Examples of organic polybasic acids include unsaturated polybasic acids such as maleic acid, fumaric acid, itaconic acid, and citraconic acid, which are used in the production of general unsaturated polyesters, and unsaturated polybasic acids such as maleic anhydride. It contains an anhydride as an essential component and a saturated acid such as phthalic acid, terephthalic acid, isophthalic acid, and adipic acid as an optional component. Of course, organic polybasic acids may be used alone or in combination.

Examples of polyhydric alcohols include ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, dipropylene glycol, 1,3-butanediol, 1,6-hexanediol, 1,6-cyclohexanediol, neopentyl glycol, glycerin, and triethylene glycol. Methylolpropane, pentaerythritol,
Sorbitol, hydrogenated bisphenol A, polybutadiene glycol, propylene oxide diadduct of bisphenol A, and the like are used alone or in combination.

Examples of modified unsaturated polyesters include dicyclopentadiene or its derivatives, pentaerythritol triallyl ether as an air-drying agent, mono- or diallyl ether of glycerin, allyl glycol,
An unsaturated polyester in which an allyl compound such as allyl glycidyl ether is used as a part of the unsaturated polyester can be used.

Regarding the method for producing unsaturated polyester in the present invention,
There are no equivalent restrictions, use known reaction methods! ! ! can be sent.

For example, an organic polybasic acid and a polyhydric alcohol are reacted at a reaction temperature of 160 to 230°C, and the reaction proceeds by distilling the resulting condensed water out of the system. g- Determine the end point of the reaction using a small amount of acid if necessary.

The entire amount of the organic polybasic acid used in the present invention may be charged at the same time and reacted with the polyhydric alcohol, or after a part of the organic polybasic acid is reacted with the polyhydric alcohol in advance,
The remaining organic polybasic acid may be added and reacted.

Further, if necessary, dicyclopentadiene, a derivative thereof, or an allyl compound may be added for reaction.

Epoxy acrylates that can be used in the present invention include:
It is an epoxy acrylate obtained by the reaction of an epoxy resin and an unsaturated basic acid, or a modified product thereof. There are no restrictions on epoxy acrylate, and epoxy resins include bisphenol A diglycidyl ether, phenol novolac glycidyl ether, cresol novolak glycidyl ether, polyethylene glycol diglycidyl ether, phthalic acid diglycidyl ester, adipic acid diglycidyl ester, and hexahydrophthalic acid. Acid diglycidyl ester, epoxidized polybutadiene, etc. are used alone or in combination.

In addition, the above-mentioned epoxy resin was preliminarily mixed with bisphenol A, ethylene glycol, diethylene glycol, etc.
Epoxy resins that have been modified in advance with polyhydric alcohols such as polyethylene glycol, organic polybasic acids such as phthalic acid, maleic acid, and fumaric acid, or their anhydrides can also be used.

As the unsaturated basic acid, acrylic acid, methacrylic acid, etc. are used alone or in combination.

The epoxy acrylate in the present invention can be obtained using a known reaction method.

For example, epoxy resin and unsaturated basic acid have a concentration of 90 to 150
React at ℃. If necessary, a known polymerization inhibitor or (meth)acrylate polymerizable monomer may be added, or air may be blown into the reaction mixture. Further, the unsaturated basic acid can be added in its entirety, continuously added dropwise, or added in portions. There are no particular restrictions on these synthesis conditions.

Moreover, those obtained by reacting an oligomer such as polyester or polybutadiene having a carboxyl group at the terminal with an unsaturated epoxy such as glycidyl methacrylate at 90 to 150°C can also be used in the present invention.

There are no restrictions on the urethane acrylate that can be used in the present invention, and urethane acrylates synthesized from polyols, polyisocyanates, and hydroxy (meth)acrylates are typical.

Polyol components include polyether polyols such as polyethylene glycol and polypropylene glycol, ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, triethylene glycol, 13-butanediol, 1,6-hexanediol, hydrogenated bisphenol A, and bisphenol. A
Polyhydric alcohols such as propylene oxide diadducts, or polyhydric alcohols and organic polybasic acids such as maleic acid, fumaric acid, itaconic acid, phthalic acid, terephthalic acid, isophthalic acid, adipic acid, or maleic anhydride. Polyester polyols obtained from anhydrides of organic polybasic acids, polycaprolactones having terminal hydroxyl groups, polybutadiene, etc. are used alone or in combination. Of course, there is no problem even if two or more of the polyhydric alcohols and organic polybasic acids used in the polyester polyol are used in combination.

As the polyisocyanate, tolylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, etc. are used. As the hydroxy (meth)acrylate, 2-hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, etc. are used.

The urethane acrylate in the present invention can be obtained using a known reaction method. For example, in the step reaction, polyol and polyisocyanate are mixed at a reaction temperature of 50 to 1
5. In the second stage reaction, the prepolymer and hydroxy (meth)acrylate are reacted at 50° C. using a known reaction catalyst such as dibutyltin silaurylate as necessary to obtain a prepolymer with terminal isocyanate. Urethane acrylate can be obtained by reacting at a temperature of 50 to 150° C. using a reaction catalyst such as dilaurate if necessary.

The polyene polythiol used in the present invention is a compound containing an unsaturated cycloacecool group having two or more unsaturated cycloacecool groups in one molecule, and a compound having two or more mercapto groups (-8H) in one molecule. A product made by reacting a polythiol compound with an unsaturated cycloacetal group:
The equivalent ratio of mercapto groups is from 0.6 to 161.

Examples of unsaturated cycloacecool group-containing compounds include diarylidenepentaerythritol, triarylidenetyl and toll, and addition of diarylidenepentaerythritol and a compound containing two or more OH groups and/or SH groups per molecule in total. products, reaction products of diarylidene pentaerythritol with phenols, arylsul7one amides or mixtures thereof, reaction products of monoallylidene trimethylolpropane and/or monoallylidene trimethyloleethane with polyisocyanate compounds,
Addition half ester of monoallylidene trimethylolpropane and/or monoallylidene trimethylolethane and a carboxylic acid anhydride having two or more acid anhydride groups in one molecule, monoallylidene trimethylolpropane and monoallylidene There are compounds obtained by reacting an addition half ester of trimethylolethane and a carboxylic acid anhydride with an epoxy compound.

Polythiol compounds having two or more mercapto groups (-8l-1) in one molecule include thioglycolic acid, ester compounds of β-mercaptopro and onic acid, or mercaptosuccinic acid and polyhydric alcohol. .

These unsaturated polyesters, epoxy acrylates,
Urethane acrylate or polyene polythiol is
Since it is a radical curable oligomer, pt-butylcatechol, 2,5-di-butylhydroquinone,
Mono-t-butylhydroquinone, 2,5-di-t-amylhydroquinone, toluhydroquinone, trimethylhydroquinone, hydroquinone, p-benzoquinone,
Polymerization inhibitors such as naphthoquinone, p-xyloquinone, 2.5-diphenyl-p-benzoquinone, di-L-butylvalacresol, hydroquinone monomethyl ether, and phenothiazine are used alone or in combination with 0.01 to 0.0
．． It is preferable to handle it by adding it in a range of 10%.

These radical curable oligomers may be used alone or in combination of two or more in order to improve properties such as hardness, elongation, sharpness, chemical resistance, and curability. Furthermore, in order to adjust the viscosity of this radically curable oligomer and improve workability, a (meth)acrylate polymerizable monomer may be added. Although there is no particular restriction on the amount added, 10 to 100 parts by weight of
It is preferable to add 200 parts by weight.

Since the coating composition of the present invention is characterized in that it can be applied to polystyrene foam, the (meth)acrylate polymerizable monomer used must have a low degree of dissolving polystyrene. As a standard, the solubility parameter of polystyrene is 8.5 to 1.
It is preferable to have a difference of 0.5 from 0.3 (cal/cm')", preferably a difference of 1.0. Typical examples include -hydroxyethyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and triethylene glycol di(meth)acrylate.Solubility parameters can also be calculated for (meth)acrylic polymerizable monomers other than those listed above. , the value is 8.0 or less or 10.9 (aal
/ am')" or more, the degree of dissolution of the polystyrene foam is small and it can be used for the purpose of the present invention.

To cure the coating composition of the present invention, an organic peroxide-based curing agent is used in the same way as in curing unsaturated polyester resins. It is also possible to adjust the curing temperature and curing time by selecting the type of organic peroxide or by using a curing accelerator such as cobalt naphthenate.

Since the coating composition of the present invention is cured using radical polymerization, oxygen contained in the air plays a role in preventing polymerization and delays the curing of the coating surface that is in contact with the air.

Incorporation of allyl compounds such as allyl glycidyl ether and trimethylolpropane diallyl ether into the oligomer backbone increases air drying properties and shortens the drying time of the coating. Further, the drying time of the coating film can be shortened even if paraffins are added by a known method.

The coating composition of the present invention can be imparted with thixotropic properties by adding a species modification imparting agent,
Viscosity can be adjusted by adding monomers, so
It can easily provide suitable viscosity characteristics for paints.

In order to specifically explain the present invention below, parts and % in the sentences describing Examples are parts by weight and % by weight, respectively.

East J19-2 A four-bottle flask equipped with a stirrer, cooling tower, thermometer, gas inlet tube, and heating device was filled with bisphenol A type epoxy resin (Asahi Kasei Corporation) "Hachi ER-331" with an epoxy equivalent of 190.
), 144 parts of acrylic acid, 1.5 parts of triethylamine, and 0.1 part of hydroquinone were charged, and reacted at a temperature of 110°C for 5 hours while introducing air, and when the acid value reached 8 KOF119/g. It was cooled to obtain epoxy acrylate [A]. To 100 parts of this epoxy acrylate, 100 parts of trimethylolpropane triacrylate was added to obtain epoxy acrylate resin (B).

To 100 parts of this epoxy acrylate resin (1)'1 cB), 5.0 parts of conductive carbon (Ketchen Black EC, manufactured by A K Z O) was added, and the mixture was uniformly mixed with three rolls to form an antistatic paint (C). ) was obtained.

For 100 parts of antistatic paint (C), 1.0 part of methyl ethyl ketone peroxide and 0.0 part of cobalt naphthenate.
After adding 5 parts, it was applied to a thickness of 300μ on a 30x expanded polystyrene foam board.

Cured at room temperature. Gelation time was 25 minutes.

When the state of the coating film was examined after it had hardened, the foam remained in its original shape without dissolving. Also,! ! ! When the surface resistivity of the film was measured, it was found to be 1.6 x 10''Ω, and a coating film having an antistatic effect was obtained.

Coordination 1 To 100 parts of epoxy acrylate (A) of Example 1, 50 parts of styrene monomer, conductive carbon (AK
After adding 5.0 parts of Ketschen Black EC (manufactured by ZO) and mixing uniformly with three rolls, 1.5 parts of methyl ethyl ketone peroxide and 0.75 parts of cobalt naphthenate were added, and a 30 times expanded polystyrene foam board was added. When applied on top of the foam, the foam began to dissolve immediately after application and did not retain its original shape.

10 moles of 115-maleic anhydride, 3 moles of diethylene glycol, and 7 moles of propylene glycol were charged into the reaction vessel No. 21, and after purging with nitrogen, the temperature was raised, and after 2 hours at about 160°C, the reaction temperature was raised to 210°C. to an acid value of 28 K.
When the temperature reached OHB/Ft, the mixture was cooled and 0.02 parts of hydroquinone was added to 100 parts of ester at 130°C, and the mixture was further cooled to room temperature to obtain unsaturated polyester CA).

After adding and dissolving 100 parts of 2-hydroxyethyl methacrylate to 100 parts of unsaturated polyester (A), conductive carbon (#3950 manufactured by Mitsubishi Kasei Corporation) was added.
5.0 parts and 50 parts of aluminum powder were added and mixed uniformly using three rolls to obtain an antistatic paint CD].

For 100 parts of antistatic paint [:D], 1.0 part of methyl ethyl ketone peroxide, 0 part of cobalt naphthenate,
Add 5 parts and 3 parts onto the 20x expanded polystyrene foam.
It was applied to a thickness of 00μ. When the state of the foam was examined after the coating film was cured, it was found that the foam had not melted and had retained its original shape. Furthermore, when the surface resistivity of the coating film was measured, it was 4×10Ω, indicating an antistatic effect.

After adding and dissolving 100 parts of styrene monomer to 100 parts of the unsaturated polyester (A) of Example 2, conductive carbon (Mitsubishi Kasei Corporation I! #3950)5.
0 parts and 50 parts of aluminum powder were added and mixed uniformly using three rolls to obtain an antistatic paint (E).

1.0 part of methyl ethyl ketone peroxide and 0.5 part of cobalt naphthenate per 100 parts of antistatic paint [E]
Add 30 parts on top of the 20x expanded polystyrene foam.
When the foam was applied to a thickness of 0 micron, the foam began to dissolve immediately after application and a coating film could not be formed.

10 moles of 115-maleic anhydride, 3 moles of diethylene glycol, and 7 moles of propylene glycol were placed in a reaction vessel No. 21, and after purging with nitrogen, the temperature was raised, and after 2 hours at about 160°C, the reaction temperature was raised to 210°C. ℃ and the acid value is 4.
When the amount reached 0 KOHmg 7g, it was cooled to obtain unsaturated polyester CF).

To 100 parts of this unsaturated polyester CF), 5 parts of maleic anhydride, 28 parts of trimethylolpropane diallyl ether
parts, adding 0.03 parts of hydroquinone, 110-170 parts
React at ℃ for 3.5 hours, acid value is 28 KOFI*y/y
When the temperature reached 80° C., cooling was started, and 100 parts of 2-hydroxyethyl methacrylate was added at 80° C. to obtain an unsaturated polyester resin (G).

To 100 parts of this unsaturated polyester [:G], 5.0 parts of conductive carbon (Ketchen Black EC manufactured by A K Z O) was added, and after uniformly mixing with three rolls, 1 part of methyl ethyl ketone peroxide was added. 0 parts and 0.5 parts of cobalt naphthenate were added and applied to a thickness of 300 microns on a 20 times expanded polystyrene foam. The coating film is approximately 4
After drying for a few hours, the surface resistivity was measured after 24 hours and found to be 7 x 10Ω. Further, no dissolution or deformation of the polystyrene foam was observed.

〔Effect of the invention〕

The antistatic paint of the present invention maintains the excellent workability and solvent-free characteristics of unsaturated polyester resin,
In addition, since the disadvantage of unsaturated polyester resin in that it dissolves polystyrene foams is improved, it contributes to improved production efficiency and can significantly widen the range of application.

Patent applicant: Showa Kobunshi Co., Ltd.

Claims (1)

[Claims] At least one radically curable oligomer selected from the group consisting of unsaturated polyester, epoxy acrylate, urethane acrylate, and polyene polythiol, and optionally a (meth)acrylate polymerizable monomer per 100 parts by weight of the oligomer. An antistatic coating composition comprising 2 to 300 parts by weight of a conductive filler uniformly dispersed in 100 parts by weight of a curable composition obtained by adding 200 parts by weight or less.