JPS6268785A - Production of printed styrene resin article - Google Patents

Abstract

PURPOSE:To obtain abrasion resistance, by printing images on a desired surface of a molded styrene resin article by using an ink comprising a dispersant having a dissolving power in a specified range, thereby infiltrating the ink into the resin article while restraining evaporation of the dispersant. CONSTITUTION:A modified styrene resin obtained by replacing a portion or the entire portion of styrene by alpha-methylstyrene, by replacing a portion or the entire portion of acrylonitrile by methacrylnitrile or by copolymerization of methyl methacrylate, ethyl acrylate, butyl acrylate, N-phenylmaleinimide or the like may be used as a styrene resin. Images are printed on a desired surface of a molded article of the styrene resin by using an ink comprising a dispersant having a solubility parameter in the range of 8.5-11.5(cal/cc)<1/2>. The molded body is wholly put into a hermetically sealed system or a covering material is brought into contact with the printed surface to restrain evaporation, thereby diffusing the dispersant to the side of the resin of the main body of the molded article and simultaneously infiltrating the ink into the resin. By this method, the molded styrene resin article is made suitable for practical use.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a method for manufacturing printed products using styrenic resin. Specifically, an ink using a dispersion medium with a solubility parameter within a specific range is printed on a styrenic resin molded product, and then the ink is printed at a specific temperature under conditions that suppress the dispersion medium from evaporating from the printing surface. The present invention relates to a method for manufacturing a printed product, which is characterized by carrying out a knife-edge heat treatment.

(Prior Art) Printing methods such as hot stamp printing and silk screen printing have been used to produce printed synthetic resin molded products.

For example, desk-top electronic calculators, telephones, televisions, radios, video cameras, car stereos, and computer equipment are equipped with a large number of push-button switches. The printed surfaces of these switch buttons are subjected to a bushing action frequently and over a long period of time during use, so they are wear-resistant and the printed characters, symbols, and figures remain clear over a long period of time. must be displayed.

(Problem to be solved by the invention) However, conventional printing methods such as hot stamp printing and silk screen printing have poor abrasion resistance, and printed characters become difficult to see over time. Therefore, there has been a long-awaited development of a method for manufacturing molded products for these uses using printing means that has excellent wear resistance.

Recently, as shown in JP-A-60-5473, polybutylene terephthalate resin (hereinafter referred to as PBT resin)
A transfer printing method has been studied in which characters, symbols, figures, etc. are printed on polyester resin molded products such as by heating transfer paper on which letters, symbols, figures, etc. have been formed using sublimation ink. By selecting appropriate dyes, it has become possible to print with wear resistance. However, in order to obtain a molded article using polyester resin, advanced injection molding technology is required, and the price of the resin is also higher than that of general-purpose resins.

On the other hand, when this transfer printing method for polyester resin is used for styrene resin, the transfer temperature becomes high due to the high molecular weight of the dye, and although this does not cause problems with polyester resin, styrene resin causes deformation due to heat. There are many cases. Furthermore, if transfer is performed at a relatively low temperature to suppress deformation, sufficient penetration depth cannot be obtained, resulting in a lack of wear resistance.

In any case, if styrene resin is printed using a transfer printing method for polyester resin, a product that can withstand practical use cannot be obtained.

The present invention is to form characters, symbols, figures, etc. on a styrene resin molded product by a printing method, and to obtain sufficient penetration depth and wear resistance at a low temperature where the styrene resin molded product will not be thermally deformed. With this in mind, the present inventor has conducted extensive research into methods for producing styrene-based resin printed products, and as a result has completed the present invention.

(Means for solving the problem) The solubility parameter is 8.5 to 11.5 (cal/CC)”2 for the required surface of the styrene resin molded product.
Printing is carried out using an ink using a dispersion medium in the range of , and the ink is permeated in a temperature range in which the molded article does not deform while suppressing volatilization of the dispersion medium so as not to evaporate the dispersion medium. This is a method for manufacturing styrenic resin printed products.

Next, the present invention will be explained in detail.

The styrene resin that is the material for the molded product used in the present invention is
Examples include styrene resin, AS resin (acrylonitrile, styrene copolymer resin), ABSII resin (acrylonitrile, butadiene, styrene copolymer resin), AA
Examples include S resin (acrylonitrile, acrylic acid ester, styrene copolymer resin), AC8 resin (acrylonitrile, chlorinated polyethylene, styrene copolymer resin), and AE8 resin (acrylonitrile, EPR rubber, styrene copolymer resin). In the styrenic resin industry, substitution of some or all of styrene with α-methylstyrene, some or all of acrylonitrile with methacrylnitrile, or substitution of methyl methacrylate, ethyl acrylate, butyl acrylate, N
- Copolymerization of phenylmaleimide and the like is a commonly used means, and such modified styrenic resins can also be used in the molded articles of the present invention.

In the present invention, the dispersion medium of the ink used has a solubility parameter of 8.5 to 11.5 (ca, 1/cc)'
It needs to be in the range of 2. Here, the solubility parameter refers to the brand lamp (J, Br.
andrup) and inmargut (E, H, Imm
ergut), Polymer Handbook (Polymer Handbook)
er Handbook) 2nd edition IV-337~■-
Using the solubility parameter values listed on page 359, the solubility parameter δT of the mixed dispersion medium is determined by the solubility parameter δ1 of each of the n types of dispersion medium and its weight fraction f.
1 using equation (1).

The solubility parameter of the dispersion medium is 8.5 (cal/cc
)'/2 or less than 11.5 (cal/cc)17
If it exceeds 2, the resulting product printed on a styrene resin molded product may have thin cracks on the optical surface, or
The ink does not penetrate into the interior very well, and the abrasion resistance of printed characters and symbols is poor, which is undesirable. With some of these solvents, after printing, the ink does not penetrate into the interior at all, but simply rests on the surface.

For styrene resin molded products, if the solubility parameter is 8.5 to 11.5 (cal/cc) l/2 Te,
Particularly effective in deep penetration and wear resistance.

Preferred dispersion media include, for example, 2-methoxyethanol, 2-ethoxyethanol, 2-7'')oxyethanol, 2-(hexyloxy)ethanol, 2-
Ethers such as phenoxyethanol and 2-(benzyloxy)ethanol, those having two functional groups of alcohols, aromatic hydrocarbons such as benzene, toluene (ortho, meta, para) xylene, ethylbenzene, isopropylbenzene and mesitylene, Ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, diethyl ketone, methyl acetate, ethyl acetate, propyl acetate, inpropyl acetate, butyl acetate, isobutyl acetate,
Acetate esters such as 8θC-butyl acetate, pentyl acetate and impentyl acetate, formate esters such as methyl formate, ethyl formate, propyl formate, butyl formate, isobutyl formate and pentyl formate, methyl propionate, ethyl propionate, zolopion Zoropionic acid esters such as butyl acid and pentyl chloride, butyric acid esters such as methyl butyrate, ethyl butyrate and butyl butyrate, methanol, ethanol, 1-propanol, 2-propanol, 1-sitanol, 2-butanol, isobutyl alcohol ,z
ert, -butyl alcohol, 1-pentanol, 2-
Alcohols such as pentanol, 6-pentanol, 2-methyl-1-butanol, impentyl alcohol, tert-pentyl alcohol, 3-methyl-2-butanol, neopentyl A/7 #: I-l and 1-hexanol , diethyl ether, zozolopyl ether,
Ethers such as diisoprozyl ether, dibutyl ether, and anisole are used. Among these, the solubility parameter alone is 8.5 to 11-5 (ca
l/cc) l/2cr) Range 1c Entering Nye dispersion tlX
However, it shows a good effect as a mixed dispersion medium.

flJ, t is methanol, ethanol.

In the present invention, the ink using the dispersion medium is printed on the required surface of a styrene-based resin molded product (hereinafter simply referred to as a molded product), but there are no particular restrictions on the printing method, and any method that is more advantageous depending on the shape of the molded product may be used. You can choose your method. For example, printing includes coating, silk screen printing, tampo printing, dry offset printing, pad printing, etc. That is, when the printing surface of the molded product is relatively flat, screen printing or dry offset printing can be used, and when it has unevenness, tampo printing, pad printing, etc. can be used.

The printed ink is permeated into the molded product through heat treatment, but at this time, it is necessary to suppress evaporation of the ink dispersion medium from the printed surface of the molded product. In the present invention, the molded article is sealed for this purpose.

A specific method for sealing is to place the entire molded product into a closed system such as an autoclave or pressure cooker to prevent the dispersion medium from evaporating into the atmosphere, and to prevent the dispersion medium from evaporating into the air. Partial pressure of medium (11JIP+2 or less, however.

10kl? A method of suppressing the evaporation of the dispersion medium by increasing the dispersion medium (the effect is the same even if it exceeds /α2) and a method of suppressing evaporation by bringing a coating material into contact with the printing surface are included.

Here, the covering material can be a glass metal, ceramic, silicone rubber, etc. tube that is hardly permeable to gas or liquid. In either case, the dispersion medium is diffused into the resin side of the molded article body and at the same time penetrates the ink.

Here, penetration means that the ink printed on the surface of the molded article substantially effectively migrates into the interior of the molded article.

Next, the molded article after ink printing is put into a closed container or covered with a coating material, and then penetration is measured, but there are no particular restrictions on the conditions at that time. Regarding the effect of temperature during coating, heating shortens the time for penetration, but it is preferable to heat the molded article to such an extent that it does not deform, and 20° to 180° C. is preferable. The temperature is substantially more preferably 700 to 180°C, although it varies depending on the ratio of the dispersion medium and ink. If the temperature is lower than 20°C, the penetration rate is slow, and if the temperature exceeds 180°C, thermal deformation of the molded product itself occurs.

The ink used in the present invention is not particularly limited, but as long as the ink contains a solvent in addition to dyes, pigments, surfactants, and stabilizers, it can be mixed with a dispersion medium to form a new dispersion medium. When the solubility parameter of the mixed dispersion medium is 8.5
It is necessary to be in the range of ~11.5 (cal/cc)/2.

If the adhesion of the ink film components is weak and easily peels off after printing, the ink cannot be used as is, and further post-treatment such as coating the printed surface or cleaning excess ink is required. For this reason, it is desirable that the ink film components firmly adhere to the light surface of the molded product after printing. By using the dispersion medium of the present invention, the ink film component can also be permeated into the molded article, and since the ink film component does not peel off and the entire ink component permeates, post-treatment such as washing is not necessary.

(Example) Examples of the present invention will be shown below, but the present invention is not limited thereto. In addition, all parts shown in Examples and Comparative Examples are based on weight.

Example 1 A key top for computer equipment is used as a styrene resin molded product. The key top molded product is ABS resin manufactured by Denki Kagaku Kogyo Co., Ltd., product name "Denka ABS GR-2".
0004, type TS-50 manufactured by Nissei Jushi Kogyo Co., Ltd.
A key top (18 x 18 x 12 Hmum) was obtained using a 12-cavity mold.

The ink used had the composition shown in Table 1. This ink was mixed with butyl cellosolve having a solubility parameter of 10.5 at a volume ratio of 1:1 to obtain a printing ink. The solubility parameter of the mixed dispersion medium at this time is δ = 10.0
It is.

The printing method used was silk screen printing.

Immediately after printing on the key top surface using a silk screen printing machine, PSL-20 manufactured by Tabai Espec Co., Ltd.
In an i-temperature tester, the material shown in Table 2, which had been heated in advance to 120° C., was removed from the printed surface of the key top to ensure penetration. The coating time was 45 seconds in each case.

Incidentally, the measured values of the Examples and Comparative Examples described below were all determined by the following method.

Penetration depth: The penetrated key top is immersed in liquid nitrogen, the temperature is lowered to below the Tg point of the key top material resin, and the key top surface is broken at the printed characters, symbols, and figures, and the cross section is was observed using a TTJM-200BD universal tool microscope manufactured by Tokyo Kogaku Kikai Co., Ltd., and the degree of immersion of the ink was read. Those with a permeability of 600 μm or more are classified as A, those with a permeability of less than 300 μm and 200 μm or more are classified as B, those with a permeability of less than 200 μm and 100 μm or more are classified as C, and those with a permeability of 100 μm or less are classified as D.

Wear resistance: Grinding wheel (count 400, abrasive grain material A, grinding wheel diameter 8)
A Tokiwa Seiki Kogyo @) EpM-1B mirror machine with a load of 0.5 mm and an amplitude of 0.5 scale was placed with the printed surface of the key top under the grindstone, and some of the printed characters were The time it took for it to disappear was measured. A case where the time was 600 seconds or more was shown as A, a case where the time was less than 600 seconds, a case where the time was 300 seconds or more was shown as B, and a case where the time was less than 300 seconds was shown as C.

Table 1 Ink composition/4 I:N As is clear from the examples of klJ, the coating is not particularly limited, and in any case, the printing ink has a thickness of 600 μm.
Since it took more than 600 seconds for the characters to permeate and to disappear even in the abrasion resistance test using a mirror machine, it can be seen that the ink coating material is effective as a printing ink coating material for the present invention in both cases.

Example 2 Table 6 shows the composition of the styrene resin. Both are numerical values indicating weight ratios.

These compositions were mixed in a Henschelmi medium, and then supplied to a VC-40 (vented single-screw extruder) manufactured by Chuo Kigurumi Seisakusho Co., Ltd. to obtain pellets.

The obtained pellets were molded in the same key top mold as in Example 1, silk-screen printed, covered with a glass coating to allow the printing ink to penetrate, and then the penetration depth and abrasion resistance were measured. .

Example 3 A mixture of components (A-3), (A-4), and (A-6) in Insert 3 with each of K (A-5) and (A-7) was prepared as Example 2. In the same way, it was made into pellets and key tops were formed, printed and infiltrated, and the penetration depth and abrasion resistance were evaluated.

In all of the experimental examples, penetration was similar to Example 2, and wear resistance was also obtained.

Example 4 Experiments N1114, 15, L17 and -21 of Example B
KF 96100 manufactured by Shin-Etsu Chemical Co., Ltd.
00 centipoise (B-1) and KF96E500 centipoise (B-2) manufactured by Shin-Etsu Chemical Co., Ltd. were added in two parts each, pelletized, molded into a key tomp, and glass was used as the material to be molded. was printed and penetrated in the same manner as in Example 1, and the penetration depth and abrasion resistance were evaluated.

As shown in Table 6, as seen in Experiments No. 14, No. 15, and No. 21, it was observed that the addition of silicone oil improved the wear resistance.

Example 5, Comparative Examples 1 and 2 In Example 5, the following steps A to 2 were carried out as a dispersion medium to be mixed with the ink shown in Table 1 in the same manner as in Example 1 except that glass lath was used as the material.

These dispersion media were mixed with the ink in Table 1 at a volume ratio of 1:1 and used as a printing ink. At this time, the solubility parameters of the mixed dispersion medium of the printing ink were shown in the column X in the table. .

As a comparative example, a comparative example is shown in which n-decane with a solubility parameter value of a=6.6 and methanol with a solubility parameter value of δ=14.5 were used as dispersion media. At this time, the solubility parameters of the mixed dispersion medium of the printing ink were 8.05 and 12.0, respectively.
It is 0.

As is clear, δ=8.5~11.5 (cal/
Key tops manufactured using dispersion media other than cc)'2 have low penetration and low abrasion resistance, and are therefore not suitable as key top materials. However, δ = 8.5~11.5 (ca
When a dispersion medium in the range of l 2 /cc)'1 is used, the method of the present invention provides a printed key top with a large penetration depth and high abrasion resistance.

Example 6, Comparative Example 3 The coating material and the glass dispersion medium were Ptylcelon Luso (s, p value 1
0.5) and the penetration temperature was set to 70'0.1700C to penetrate the key top.

The key top material, printing method, ink, etc. are the same as in Example 1.

As Comparative Example 3, penetration was attempted at 200°C, and although the degree of penetration was high, the key top body was deformed due to heat and could not be put to practical use as a key top.

Example 7 As a method for achieving infiltration, an example of sealing in an autoclave will be shown. Key tops printed with the same printing ink as in Example 1 were placed in an autoclave that had been preheated to a predetermined temperature without using a roofing material, and sealed to allow the printing ink to penetrate. Wear resistance was measured. The results are shown in Table 9.

This marine use is equivalent to Example 2, and is applicable to methi 1/1 resin key pumps under conditions that do not evaporate the dispersion medium with the solubility parameter specified in the claims. It is well known that the autoclave can be kept tightly closed.

Example 8 In this example, nitrogen gas was further placed in an autoclave at the same time as key tops printed with the same printing ink as in Example 1 were placed, and printing was attempted in the presence of nitrogen gas partial pressure. The partial pressure of the sealed nitrogen gas is 6.5 at 70'C and 8.5kl at 97C1n2.120°C? /σ2.

As shown in Table 10, the amount of addition needles for component B was 2 parts. Compared to Example 7, the penetration depth is slightly lower.

However, all of them have shown sufficient results for practical use.

(Effect of the invention) From the various experimental results described above, it was found that 8.5 to 11.5 (cal/cc)1
If a molded article is manufactured by printing using an ink using a dispersion medium in the range of 72, sealing the dispersion medium so as not to evaporate, and permeating the molded article at a temperature range that does not deform the molded article, This has the effect of making styrene-based resin molded products, which have hitherto been difficult to achieve in terms of heat resistance and shore damage resistance, practical.

Patent Applicant Denki Kagaku Kogyo Co., Ltd. Procedural Amendment Written October 14, 1985 Director General of the Patent Office Michibe Uga 1. Indication of Matter A 1. 1985 Patent Application No. 206658 2. Name of Invention Styrene-based Manufacturing method for resin printed products 3, relationship with the person making the amendment Patent applicant address ■100 1-4-1 Yurakucho, Chiyoda-ku, Tokyo Column 5 of the detailed description of the invention in the specification, Contents of the amendment (1) ), 1 toluene (ortho,
” is corrected to “Toluene, (ortho,”).

Claims (1)

[Claims] Printing is performed on the required surface of the styrene-based resin molded product using an ink using a dispersion medium with a solubility parameter in the range of 8.5 to 11.5 (cal/cc) 1/2. A method for manufacturing a styrenic resin printed product, characterized in that the ink is infiltrated in a temperature range that does not deform the molded product while suppressing volatilization of the dispersion medium so as not to evaporate the dispersion medium.