JPH04348118A - Photo-setting resin composition - Google Patents

Abstract

PURPOSE:To obtain the subject composition, useful as a pattern for casting clasps in producing a partial denture base and excellent in operating efficiency, surface characteristics, etc., by blending diglycidyl phthalate methacrylate with fine powder of an organic polymer and a photochemical radical polymerization initiator in specific amounts. CONSTITUTION:The objective composition is obtained by blending (A) 30-60 pts.wt. diglycidyl phthalate methacrylate expressed by the formula with (B) 40-70 pts.wt. fine powder of an organic polymer (e.g. paraffin wax or polymethyl methacrylate) having 1-50mum average particle diameter and 10000-2000000 molecular weight and (C) a photochemical radical polymerization initiator (preferably camphorquinone, etc.) in an amount of 0.04-6 pts.wt. (preferably 0.1-4 pts.wt.) based on 100 pts.wt. total amount of the components (A) and (B), stirring and mixing the resultant blend.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photocurable resin composition. More specifically, when fabricating partial dentures, cast clasps are metal components that provide grip (resistance to lateral movement), retention (resistance to attachment and removal), and support (resistance to occlusal pressure) to the denture. The present invention relates to a photocurable resin composition for making a cast clasp prototype, ie, a clasp pattern, which exhibits a theoretical shape with respect to retention strength, durability, etc. when manufactured by the lost wax method.

0002

2. Description of the Related Art Clasps are used in more than 90% of partial dentures as main and indirect retaining devices. However, the manufacturing method for cast clasps in particular is complicated, and the current situation is that the retention force, fitting accuracy, and form of the given arm portion are not always satisfactory.

[0003] In the conventional manufacturing method of a cast clasp, first, an impression of the patient's jaw inside the oral cavity is taken, and a working model is made of superhard plaster or the like. Next, in order to design a clasp that will serve as a retainer, the retainer tooth portion on this working model is surveyed. Surveying is a task performed to find the maximum bulge of the remaining teeth and alveolar ridge on the model, as well as to examine their mutual parallel relationships.It is used to determine the direction of denture attachment/removal, the determination of teeth to be retained, and the identification of block-out areas. This is an extremely important task in denture manufacturing, as it involves measuring the amount of undercut, determining the position of the clasp, etc.

[0004] Important factors that influence the retention force of the clasp include the length, thickness, cross-sectional form of the clasp arm, Young's modulus of the alloy used, the set amount of undercut, and the curvature of the tooth surface of the retention tooth. Can be mentioned.

[0005] When making a cast clasp using a paraffin wax pattern, the retention force of the clasp is as follows:
It is possible to control the amount of undercut used, the thickness of the pattern, and the selection of different cross-sectional forms.
At the time of surveying and denture design, it is necessary to design a clasp that corresponds to the condition of the periodontal tissue of the retained tooth.

When the design and blockout for the working model are completed, next, in order to produce the wax pattern of the clasp, an impression is taken again (double impression) of the retained tooth part that was blocked out according to the design, and the working model is used as an investment material for the model. Replace with Next, taking into consideration the precise control of the retention force of the clasp, the paraffin wax clasp pattern is bent with fingers and attached to the investment material for the model using adhesive, and the rest and legs are formed. , planting sprue. Next, without removing this paraffin wax clasp pattern from the model investment material, the entire model investment material is buried in casting investment material, and after the investment material has hardened, the paraffin wax clasp pattern is heated in a furnace. After incineration, the molten metal is poured into a mold with the resulting clasp pattern, cooled, and indexed and polished to complete the clasp (hereinafter, this method is referred to as the ``embedding method'').

[0007]

[Problems to be Solved by the Invention] The method for manufacturing the cast clasp described above has the following problems because the material for forming the clasp pattern is paraffin wax.

[0008] Since paraffin wax cannot be elastically deformed at all and deforms plastically, it cannot be removed from the undercut portion of the retaining tooth on the working model through the maximum protrusion.

Forcible removal will cause permanent deformation, making it impossible to obtain an accurate fit. For this reason, it is not possible to create an accurate clasp with controlled retention force. Therefore, the clasp pattern of paraffin wax is always made by making a double impression of the working model, replacing it with the investment material for the model, molding the clasp pattern on the investment material for the model, and burying it together with the investment material for the model in the investment material for casting. The so-called burial method must be performed for each type. For this reason, the clasp manufacturing process is complicated and requires a long manufacturing time, and the material cost is also large.

[0010] Since the clasp pattern made of paraffin wax does not adhere to the investment material for the model or plaster, a special adhesive must be used. Therefore, the resulting clasp has an error in adhesive thickness of about 50 μm, making it impossible to obtain a well-fitting clasp.

[0011] The paraffin wax clasp pattern is bonded to the investment material for the model by pressing it with the hands and fingers using an adhesive, but because the strength of the investment material is low at that time, the particles of the investment material fall off and maintain the shape of the tooth. and the surface quality deteriorates. The peeled off particles of the investment material adhere to the paraffin wax clasp pattern, making it impossible to create a cast clasp with good surface quality.

■The clasp pattern of paraffin wax is a polymer with high crystallinity and relatively low molecular weight.
Although the glass transition temperature Tg and melting point Tm are very close to each other, it is a substance that does not have a glass transition point like metals, so if the rate of temperature rise during heating and incineration of wax is too high, the melted wax will boil and turn into gas. As the wax expands, the investment material is suddenly pressurized, causing cracks in the investment material and roughening of the inner surface of the investment material.

The present invention aims to solve these problems by developing a clasp pattern made of a new material to replace paraffin wax.

On the other hand, there is also a method of using pattern resin instead of pattern wax. The resin for the pattern is
This is a PMMA-based instant-polymerizing resin, and although it has greater elasticity than pattern wax, it cures slowly and does not have sufficient elasticity, so it must be removed from the undercut part of the working model during the working time, similar to pattern wax. with permanent deformation.

[0015] If a photopolymerizable compound is used instead of chemical polymerization, it is possible to obtain a pattern resin that hardens quickly. JP-A-1-110609 discloses a resin composition for photopolymerizable patterns using a photopolymerizable compound containing at least one ethylenic double bond that is solid at room temperature. Although the same publication describes the operability, strength, and castability of resin, the operability and castability are not sufficient, and especially when a gypsum-based investment material is used for casting, the surface of the cast It's so bad that it's practically unusable. Conventionally, such lost wax technology has not been achieved, although there have been many requests not only for dental applications but also for general industrial applications.

[0016]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a novel photocurable resin composition useful in the general industrial field and in dentistry.

Another object of the present invention is to reduce the retention force when manufacturing a cast clasp, which is a metal component that provides gripping, maintenance, and support for the denture, by the lost wax method when manufacturing a partial denture. It is an object of the present invention to provide a photocurable resin composition for making a prototype of a cast clasp, that is, a clasp pattern, which exhibits a theoretical shape with respect to durability and the like.

Further objects and advantages of the invention will become apparent from the following description.

According to the present invention, the above objects and advantages of the present invention are as follows: (A) The following formula 1

[0020]

[Case 2]

30 to 60 parts by weight of diglycidyl phthalate methacrylate represented by: and (B) an average particle size of 1 to 50 μm.
, fine organic polymer powder with a molecular weight of 10,000 to 2 million 40 to 7
0 parts by weight and (C) radical photopolymerization initiator (A) component and (
This is achieved by a photocurable resin composition containing 0.04 to 6 parts by weight of component B) per 100 parts by weight in total.

As described above, the photocurable resin composition of the present invention contains the three components (A), (B) and (C) in specific proportions.

Diglycidyl phthalate methacrylate (A
) is a compound represented by the above formula 1. Diglycidyl phthalate methacrylate is used in an amount of 30 to 60 parts by weight, preferably 35 to 55 parts by weight.

The organic polymer of the organic polymer fine powder (B) is one that does not dissolve in diglycidyl phthalate methacrylate or has very low solubility, such as paraffin wax, polymethyl methacrylate,
Preferred examples include polyethyl methacrylate, polybutyl methacrylate, starch, and paraformaldehyde.

[0025] These organic polymers preferably have a molecular weight of 100
It is desirable that the ash content is 0 ppm or less, more preferably 500 ppm or less.

Further, these organic polymers have a number average molecular weight of 10,000 to 2,000,000, preferably 20,000 to 1,000,000.

[0027] The fine powder of organic polymer has an average particle size of 1 to
50μ, preferably 2 to 30μ.

The fine powder of organic polymer is used in an amount of 40 to 70 parts by weight, preferably 45 to 65 parts by weight.

As the photoradical polymerization initiator (C), any known one may be used without distinction, but camphorquinone, benzyl, benzoyl methyl ether, benzoyl isopropyl ether, thioxanthone derivatives, benzophenone, acetophenone, etc. are preferred. can be mentioned. In addition to these, polymerization accelerators, stabilizers, etc. may be used in combination. In addition, if necessary, other radically polymerizable monomers other than the above component (A) may be added to the component (A) and (
It can also be used in a proportion of 40 parts by weight or less per 100 parts by weight of component B).

The photoradical polymerization initiator is used in an amount of 0.04 to 6 parts by weight, preferably 0.1 to 4 parts by weight, per 100 parts by weight of components (A) and (B). used in

The photocurable resin composition of the present invention has the above-mentioned (A
), (B) and (C) can be produced by thoroughly stirring and mixing the three components in any order over time or simultaneously.

The present invention will be explained in detail with reference to Examples below. The present invention is not limited in any way by these Examples.

[0033]

【Example】

Example 1 Diglycidyl phthalate methacrylate (Nagase Kasei Co., Ltd., Denacol DA721) 1 g, polymethyl methacrylate (Shin Nakamura Chemical Co., Ltd., Hypal D-250M)
0.6g, paraffin wax powder (Nippon Seirin Co., Ltd.)
Frosene UF80) 0.65g, hydroquinone 0.
002g, camphorquinone 0.01g, dimethyl-p
- 0.01 g of toluidine was mixed with a spatula and defoamed under vacuum to form a paste.

Example 2 1 g of diglycidyl phthalate methacrylate, polymethyl methacrylate (Shin Nakamura Chemical Co., Ltd., Hyperal D-2)
50M) 0.6g, polymethyl methacrylate crosslinked product (
Shin Nakamura Chemical Co., Ltd., Hyperal TM-150) 0.45
g, Paraffin wax (Nippon Seirin Co., Ltd., LUVAX
0321), 0.01 g of camphorquine, and 0.01 g of dimethyl-p-toluidine were mixed with a spatula and defoamed under vacuum to form a paste.

[0035] The pastes of Examples 1 and 2 were wrapped around a cylinder with a diameter of 5 mm having an undercut of 0.5 mm up to 3/4 of the circumference, and heated with a light irradiator (for dental use, Morita Co., Ltd., α-Light) for 50 minutes. After being irradiated with light for a minute, it was removed from the undercut and buried with a gypsum-based investment material (Tokuyama Soda Co., Ltd., White Best M), and a cast made of dental gold, silver, and palladium alloy was created according to a conventional method. The operability of the paste, the surface condition of the casting, and the deformation were as shown in Table 1.

[0036]

[Table 1]

[0037]

INDUSTRIAL APPLICABILITY The photocurable resin composition of the present invention is suitably used for producing patterns for dental casting clasps.

That is, the composition of the present invention has excellent operability in producing a cast clasp pattern, and provides a cast clasp pattern with excellent surface properties and no or very little deformability.

Claims (1)

[Claims] Claim 1: (A) Diglycidyl phthalate methacrylate 30 represented by the following formula 1:
~60 parts by weight; (B) 40 to 70 parts by weight of an organic polymer fine powder with an average particle size of 1 to 50 μ and a molecular weight of 10,000 to 2 million;
C) A photocurable resin composition containing 0.04 to 6 parts by weight per 100 parts by weight of the photoradical polymerization initiator (A) and (B).