JPH0333193B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a liquid coating composition that is curable, particularly by radiation such as ultraviolet rays, and contains a liquid monofunctional (meth)acrylate having a cycloalkyl group and a rubber component. A curable composition that does not substantially contain a liquid agent is superior in terms of resource and energy savings, environmental health and safety, and when forming a film, it is easier to adjust the coating thickness and the thickness is more uniform than that of a solution type. It has many advantages such as being easy to obtain.In particular, photo-curing products have the advantage of not having any thermal effect on the coated object because they are cured without heating, so they are being actively researched and have been put into practical use. It is widely used as a surface coating for various materials, adhesives, and various other binders. By the way, in addition to the above-mentioned advantages, this type of liquid composition is required to have a viscosity that can be easily adjusted to the desired viscosity in order to improve painting workability, while the cured product must have a desired elastic modulus. It is also required to have good elongation properties and satisfy general properties such as heat resistance and electrical properties. However, conventional compositions of this type generally have the disadvantage that it is difficult to balance the above-mentioned viscosity characteristics with the properties of the cured product, and when it comes to the properties of the cured product, especially those that are photocurable, they generally have excellent flexibility. It has the disadvantage that it is inferior in general properties such as heat resistance and electrical properties, and conversely, those that are excellent in heat resistance and electrical properties are inferior in flexibility, making it difficult to satisfy both properties. Therefore, it is possible to easily balance these properties, that is, to easily adjust the desired viscosity to improve painting workability, and the cured product has the desired elastic modulus and good elongation properties. If a liquid (solvent-free) curable composition, especially a photocurable composition, can be found that satisfies various properties such as heat resistance and electrical properties, it would be possible to develop applications in various fields. is even more promising. As a result of intensive studies from this point of view, the inventor discovered that (meth)acrylate with a specific structure dissolves rubber components to a high degree, and that a desired viscosity can be easily achieved by adjusting the amount of this rubber component. In addition, a composition obtained by adding a polyfunctional (meth)acrylate and a polymerization initiator to a solution of this rubber component and, if necessary, an ordinary monofunctional (meth)acrylate, has curability, especially photocurability. I also learned that the cured product exhibits a wide range of properties, including improved flexibility due to the rubber component.
This invention was completed. That is, this invention provides a) general formula; CH ₂ =C
100 parts by weight of liquid monofunctional (meth)acrylate represented by (R)-COOR ₁ (R is hydrogen or a methyl group, R ₁ is a monovalent group having a cycloalkyl group);
b) Rubber component 2-100 parts by weight, c) General formula; CH ₂
=C(R)-COOR ₂ (R is hydrogen or methyl group, R ₂
is a chain or branched alkyl group having 8 to 18 carbon atoms)
Monofunctional (meth)acrylate expressed by 0-80
Parts by weight, d) General formula; [CH ₂ =C(R)-COO] - _o
5 to 150 parts by weight of a polyfunctional (meth)acrylate represented by R ₃ (R is hydrogen or a methyl group, R ₃ is an n-valent organic group, n≧2) and e) 0.5 parts by weight of a photopolymerization initiator
The present invention relates to a curable coating composition characterized in that it is a radiation-curable one-component composition comprising 40 parts by weight. The above composition of the present invention uses a specific monofunctional (meth)acrylate as component a, which has the property of arbitrarily dissolving the rubber component as component b. By adjusting the amount of the rubber component, the viscosity can be adjusted as desired, and thereby good coating workability can be obtained depending on the purpose of use. Further, by using a photopolymerization initiator as component e, this composition can be more easily cured with radiation such as ultraviolet rays. Moreover, the desired elasticity modulus can be obtained by the above-mentioned curing, and good elongation properties can be obtained by using the rubber components.In particular, by appropriately selecting the types and amounts of each component, it is possible to achieve a balance in the above-mentioned properties. This can be done easily, and as a result, it becomes possible to obtain a cured product that satisfies not only general properties such as heat resistance and electrical properties, but also flexibility. Furthermore, this cured product has excellent water resistance and exhibits extremely suitable performance as a coating material. In this invention, the liquid monofunctional (meth)acrylate having a cycloalkyl group used as component a is practically cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, or these. Substituents on a cycloalkyl group and (meth)acrylates in which these cycloalkyl groups are connected via a methylene or oxyethylene chain are included, and these may be used alone or in combination. These (meth)acrylates having a cycloalkyl group highly dissolve various natural or synthetic rubbers or depolymerized products thereof as component b. The rubber components include natural rubber, isoprene rubber, styrene-butadiene rubber (random or block), styrene-isoprene rubber, butadiene rubber, chloroprene rubber, butyl rubber,
Examples include polyisobutylene, nitrile rubber, and ethylene-propylene rubber. Naturally, for example, butadiene-based liquid rubber can also be used. The amount of these to be used is selected as appropriate to obtain the required viscosity, and is in the range of 2 to 100 parts by weight per 100 parts by weight of the liquid monofunctional (meth)acrylate. If it is less than 2 parts by weight, the effect of modifying properties or improving flexibility will be insufficient unless a rubber component with a fairly high molecular weight is used, and conversely, if it exceeds 100 parts by weight, it is necessary to use a rubber component with a low molecular weight. In this case, the effect of improving flexibility due to the rubber component is reduced. The composition of the present invention is prepared by dissolving the above-mentioned rubber component in a monofunctional (meth)acrylate as the above-mentioned component a, and further adding a chain or branched alkyl monofunctional (meth)acrylate as a component depending on the purpose. The acrylate can be blended in a proportion of 0 to 80 parts by weight based on 100 parts by weight of the liquid monofunctional (meth)acrylate. This monofunctional (meth)acrylate preferably has a chain or branched alkyl group with a carbon number in the range of 8 to 18, and specific examples include 2-ethylhexyl (meth)acrylate,
Decyl (meth)acrylate, lauryl (meth)
Examples include acrylate, tridecyl (meth)acrylate, and stearyl (meth)acrylate alone or in mixtures. These c components are well compatible with the solution consisting of the a and b components, and do not need to be used if a hard cured product is desired, but are necessary if a relatively soft product is desired. However, if more than 80 parts by weight is added, the improvement effect will hardly be recognized. The component d used as an essential component in this invention is for maintaining the curing speed or imparting desired hardness to the cured product, and is a polyfunctional (meth)acryloyl group having two or more (meth)acryloyl groups in the molecule.
Various monomers or oligomers known as acrylates are used. Specifically, ethylene glycol di(meth)acrylate, 1,3-propanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,3-pentanediol di(meth)acrylate
Acrylate, 1,6-hexanediol di(meth)acrylate, decamethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, dipropylene Glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, glycerol di(meth)acrylate, trimethylolpropane di(meth)acrylate, pentaerythritol di(meth)acrylate, 1,4-cyclohexanediol di(meth)acrylate Acrylate, 1,4
-benzenediol di(meth)acrylate,
1,2,4-butanetriol tri(meth)acrylate, glycerol tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate
Examples include acrylate, other similar derivatives, and oligomeric polyfunctional (meth)acrylates, which may be used alone or in combination. The amount used is 5 to 150 parts by weight per 100 parts by weight of the liquid monofunctional (meth)acrylate as component a.
It is expressed as a percentage of parts by weight. If it is less than 5 parts by weight, the effect on maintaining the curing speed will be small, and
If the amount exceeds 150 parts by weight, the cured product becomes too hard or loses compatibility, so both are unsuitable. By using a photopolymerization initiator as component e, the composition of the present invention can be easily and quickly cured with radiation such as ultraviolet rays. As the above-mentioned photopolymerization initiator, various kinds of initiators and sensitizers that are generally used for ultraviolet curable coatings can be used. For example, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin butyl ether, 2-methylbenzoin, benzophenone, Michler's ketone, benzyl, benzyl dimethyl ketal, benzyl diethyl ketal, anthraquinone, methylanthraquinone, diacetyl, acetophenone, diphenyl disulfide. Examples include hydride, anthracene, etc., and those used in combination with small amounts of sensitizing aids such as amines. Further, the composition of the present invention can be further heat-cured after being cured by radiation, using a thermal polymerization initiator if necessary in addition to the above-mentioned photopolymerization initiator. Examples of the thermal polymerization initiator include peresters such as tertiary butyl peroctoate and tertiary butyl perpivalate, percarbonate esters such as bis-(4-tertiary butylcyclohexyl)-peroxydicarbonate, and benzoyl peroxide. Diacyl peroxides such as di-tert-butyl peroxide and dicumyl peroxide, hydroperoxides such as cyclohexanone peroxide, methyl ethyl ketone peroxide, cumene hydroperoxide, and these together with 2-ethylhexanoic acid and Examples include peroxide polymerization initiators in combination with metal promoters such as cobalt naphthenic acid salts, and other azo compounds can also be used. The amount of the photopolymerization initiator or the thermal polymerization initiator used should be in the range of 0.5 to 40 parts by weight based on 100 parts by weight of the liquid monofunctional (meth)acrylate as component a. If it is less than 0.5 parts by weight, it will be difficult to initiate polymerization sufficiently, while if it is used in excess of 40 parts by weight, no particular effect will be observed and it will lack practicality, so both are inappropriate. Polymerizable unsaturated compounds such as (meth)acrylates other than those mentioned above and other allyl compounds and vinyl compounds may be added to the composition of the present invention within the range permitted in terms of curing conditions and compatibility. In addition, known thermal polymerization inhibitors are used to improve the thermal stability of the composition, known plasticizers are used to improve the flexibility of the cured product, and soluble additives are used to appropriately adjust the properties during coating. It is possible to add polymeric materials, known anti-aging agents to improve high temperature deterioration after curing, and improvers to improve adhesion to materials. As detailed above, the curable coating composition of the present invention can be adjusted to any desired viscosity by adjusting the amount of the rubber component as component (b), so that it can be applied smoothly using an appropriate coating method. On the other hand, it can be easily cured by radiation such as ultraviolet rays after coating, and the cured product satisfies various properties such as heat resistance, electrical properties, flexibility, and water resistance. It has the characteristic of being able to Examples of the present invention will be shown below in comparison with comparative examples. Examples 1 to 6 and Comparative Example 1 In Examples 1 and 2, cyclohexyl acrylate (product name: Viscoat 155, manufactured by Osaka Organic Chemical Industry Co., Ltd.) as component a was added as component b at the blending ratio (parts by weight) shown in Table 1. Isoprene rubber (synthetic isoprene rubber manufactured by Clarei Soprene Chemical Co., Ltd.)
After mixing and dissolving IR-10) into small pieces,
Furthermore, lauryl tridecyl acrylate (product name LTA, manufactured by Osaka Organic Chemical Industry Co., Ltd.) as a c component.
and 1,6-hexanediol diacrylate as component d in the proportions (parts by weight) shown in Table 1, making the total blended amount 100 parts by weight, and to this, benzyl dimethyl ketal as component e (product manufactured by Ciba Geigy). 4
Parts by weight were added to form a photocurable coating composition of the present invention. In Examples 3 to 6, cyclohexyl acrylate as component a and styrene-butadiene-styrene block copolymer as component b (product name: CALIFLEX TR-KX65, manufactured by Ciel Chemical Co., Ltd.) were mixed in the proportions (parts by weight) shown in Table 1. Dissolve, and after dissolving, mix the proportions (parts by weight) listed in Table 1 in the same manner as in Examples 1 and 2.
Add lauryl tridecyl acrylate as component c and 1,6-hexanediol diacrylate as component d, and further add 4 parts by weight of benzyl dimethyl ketal as component e, making the total blended amount 100 parts by weight, The photocurable coating composition of this invention was prepared. Moreover, in Comparative Example 1, a comparative photocurable coating composition was prepared with the same formulation as in Examples 1 to 6, except that the rubber component as component b was not used. The results of examining the viscosity and cured product properties of the compositions of these Examples and Comparative Examples are as shown in Table 1 below.

【table】

[Table] The physical properties of the cured product were determined as follows. That is, each composition is spread on a glass plate to a thickness of approximately 0.3
A solution sample was prepared by casting a sample of about 1.0 mm in diameter and tightly covered with a polyester film, and exposed to 400 mJ/cm ² under degassing using an ultraviolet exposure device with a built-in high-pressure mercury lamp to create a cured sheet. Punch out the specimen for tensile test, tensile speed 50
It was determined by performing a tensile test at mm/min. As is clear from the above results, Comparative Example 1 consists of cyclohexyl acrylate, lauryl tridecyl acrylate, and 1,6-hexanediol diacrylate and does not contain a rubber component, so its viscosity is that of a mere acrylic monomer. very low in the mixture. Therefore, although it may be possible for extremely thin coating, for example, it is difficult to put such a composition into practical use in a wide variety of fields, since a desired viscosity is required for each general purpose field. On the other hand, in the compositions of Examples 1 and 2 in which isoprene rubber was used in combination, the viscosity was widely variable due to the above rubber component, and the elastic modulus of the cured product was almost the same as that of Comparative Example 1. At the same time, a cured product with improved elongation and improved so-called toughness, which can impart good heat resistance, electrical properties, etc., has been obtained. Further, Examples 3 to 6 are those in which a styrene-butadiene-styrene block copolymer is blended as a rubber component, and as in the case of Examples 1 and 2, the viscosity characteristics are widely controlled by increasing the amount of the rubber component. be able to. At this time, as the amount of the rubber component increases, the elastic modulus decreases if the monomer types are the same (Examples 4 and 5), but this is due to lauryl tridecyl acrylate as the c component and lauryl tridecyl acrylate as the d component. A desired value can be obtained by changing the blending ratio of 1,6-hexanediol diacrylate (Example 6). Thus, according to the compositions of Examples 1 to 6,
It can be seen that the desired viscosity characteristics and desired cured product characteristics can be easily obtained, and that the composition has extremely high utility value as a coating composition. Examples 7 to 10 and Comparative Example 2 Isobornyl acrylate (monomer QM-589 manufactured by Rohm & Haas) as component a
After blending and dissolving the styrene-butadiene-styrene block copolymer as component b (same as in Examples 3 to 6) at the blending ratio (parts by weight) shown in the table,
Furthermore, lauryl tridecyl acrylate as component c and pentaerythritol triacrylate as component d are added at the blending ratio (polymerization part) shown in Table 2, and the total amount of these is 100 parts by weight, and to this is benzyl dimethyl as component e. 4 parts by weight of ketal was added to prepare this light curable coating composition. Comparative Example 2 was a comparative photocurable coating composition having the same formulation as in Examples 7 to 10, except that the rubber component as component b was not used. The results of examining the viscosity and cured product properties of the compositions of these Examples and Comparative Examples are as shown in Table 2 below.

【table】

【table】

[Table] As is clear from Table 2 above, Examples 7-
It can be seen that with composition No. 10, the viscosity properties can be modified over a wide range as shown in Table 1, and it is also possible to easily achieve both the viscosity properties and the properties of the cured product.

Claims (1)

[Claims] 1 a) Liquid monofunctional compound represented by the general formula: CH ₂ =C(R)-COOR ₁ (R is hydrogen or a methyl group, R ₁ is a monovalent group having a cycloalkyl group) (meth)acrylate 100 parts by weight, b) rubber component 2~
100 parts by weight, c) General formula; _CH2 =C(R) _-COOR2
(R is hydrogen or a methyl group, _R2 is a chain or branched alkyl group having 8 to 18 carbon atoms) 0 to 80 parts by weight of a monofunctional (meth)acrylate, d) General formula; [ _CH2 = 5 to 150 parts by weight of a polyfunctional (meth)acrylate represented by _o R ₃ (R is hydrogen or a methyl group, R ₃ is an n-valent organic group, n≧2) and e) light. A curable coating composition characterized in that it is a radiation-curable one-component composition comprising 0.5 to 40 parts by weight of a polymerization initiator.