JPS60112875A - Paste for protective sheet, and surface-protected synthetic resin molded article using the same - Google Patents

Abstract

PURPOSE:To provide a paste for the bonding of a synthetic resin plate and a protective sheet, having moderate adhesive strength, by adding an acrylic emulsion and a boron compound at a specific ratio to an aqueous solution containing a specific amount of partially saponified polyvinyl acetate. CONSTITUTION:The objective paste can be produced by adding (A) an acrylic emulsion and (B) a boron compound to (C) an aqueous solution containing 3- 15(wt)% partially saponified polyvinyl acetate. The amounts of the components A and B are 1-200% and 0.01-20% based on the solid component of the partially saponified polyvinyl acetate in the component C. The paste is applied to a synthetic resin plate, a protective sheet is attached thereto, and the laminate is formed to a desired form to obtain a formed product of a surface-protected synthetic resin. EFFECT:The surface-protected synthetic resin plate manufactured by the use of the objective paste is free from optical strain in thermal drawing process, and surface roughening and cracking in bending under heating.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field The present invention relates to a glue for surface protection sheets and a surface protection synthetic resin molded product using the same.

(B) Prior Art Synthetic resins have properties such as being light and easy to process, so they are widely used in a variety of applications by taking advantage of these properties. However, since the synthetic resin has a soft surface, the molded product is easily damaged by unnecessary scratches during transportation, storage, molding, etc., and has the drawback of reducing its commercial value.

To protect the surface, a paper-like sheet such as kraft paper is pasted on the resin board with a water-soluble glue, such as a 1 volume solution of partially saponified polyvinyl acetate, or starch glue, or an adhesive such as natural com is used to protect the surface. At present, pressure-sensitive protective paper coated with a chemical agent is pressure-bonded, or a pressure-sensitive adhesive or heat-sensitive synthetic polymer protective film is pasted.

However, pressure-sensitive protective sheets (made of polymer films, natural rubber, etc.) have strong adhesion, so when handling large objects, peeling is difficult.
It stains and tends to attract dust and the like to the surface, and as a result, problems such as damage to the surface during molding are likely to occur, and the price is high.

On the other hand, when covering with a paper-like sheet such as kraft paper using a water-soluble adhesive, the above-mentioned polymer film or natural
It has the advantage of avoiding the troubles that would occur when using , and being cheaper.

On the other hand, if the adhesive strength of the glue is too weak, or if the protective sort is peeled off from the synthetic resin board, a film of the protective sort, iJV, or glue may remain on the surface of the synthetic resin board (hereinafter referred to as "adhesive residue").
It is called. , and may make a contract. $1j1 If there is any remaining residue, it is necessary to thoroughly wash it off with water or alcohol. If the resin plate is heated and molded with incomplete washing, the contaminated area will affect the smoothness and transparency of the resin plate. Even if washed with water or alcohol after hot molding, the contamination will no longer disappear, and the surface of the resin plate will need to be polished. Furthermore, if a resin plate contaminated with an adhesive or the like is subjected to printing such as screen printing or photo printing as it is, the adhesiveness between the printing ink and the resin plate may be poor in the contaminated area, and the area may easily fall off. In addition, if the adhesive strength weakens, the protective paper may peel off during the transport process of the synthetic resin board, causing damage to the synthetic resin board, or the protective paper on the edges of the sheet may peel off when cutting the sheet after manufacturing. Chips generated during cutting enter the edges and cause damage to the sheet during storage, greatly reducing its commercial value. Therefore, the adhesive applied to the protective sheet must not leave any adhesive residue on the synthetic resin plate when it is peeled off, and must have appropriate adhesive strength.

In addition, in order to prevent TFIF of the synthetic resin board during the processing stage, heating and bending may be performed with the protective sheet still attached to the synthetic resin board, but the type of glue used and the resin Depending on the type, rough skin and/or cranking may occur at the bent portion that comes into direct contact with the rod heater, and in this case, the commercial value of the processed product with poor appearance will be greatly reduced.

A sizing agent using partially saponified polyvinyl acetate as a water-soluble sizing agent is an excellent sizing agent that leaves almost no adhesive residue. There was a point y11 in which rough skin and cranking occurred, and there was a strong demand for improvements in these areas.

In addition, when a sizing agent using partially saponified polyvinyl acetate is used, optical distortion occurs due to stretching unevenness when the synthetic resin plate is heated and stretched during the blow molding or vacuum forming process, and as a result, optical distortion occurs in the finished product. There is a strong demand for improvement as it significantly reduces the appearance and product value.

(c) Object of the Invention In view of the above-mentioned prior art, the object of the present invention is to have a suitable adhesive strength, greatly suppress or eliminate the occurrence of optical distortion caused by partially saponified polyvinyl acetate, and To provide a adhesive for a protective sheet, which has an aqueous solution of partially saponified polyvinyl acetate as a main ingredient, and can prevent the occurrence of roughening and cranking of the bent portion of the contact portion of a rod heater.

(d) Structure of the invention The present invention provides 3 to 1 parts of partially saponified polyvinyl acetate.
An aqueous solution containing 5% by weight, the ratio of the solid content to the solid content of the partially saponified polyvinyl acetate in the aqueous solution is 1
A paste for a protective sheet comprising an acrylic emulsion of ~200% by weight and a boron compound in a proportion of 0.01 to 20% by weight based on the solid content of partially saponified polyvinyl acetate in the aqueous solution, and a surface protection synthesis using the same. It is a resin molded product.

(B) Embodiment The partially saponified polyvinyl acetate used in the present invention preferably has a degree of saponification of 71.0% or more, including completely saponified polyvinyl alcohol with a degree of saponification of 100%. Also included.

For the acrylic emulsion used in the present invention, the required adhesive strength and adhesive residue of the glue depend on the type of partially saponified polyvinyl acetate used.

It is possible to select from any commercially available acrylic emulsions in consideration of physical properties such as molding distortion.

-11, the acrylic emulsion contains the following components.

(A) Main component monomer (60 to 100 parts by weight) An alkyl acrylate J-stell monomer whose alkyl group has 1 to 8 carbon atoms, such as EVA, ethyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate. is included.

(B) Comonomer (20 to 40 carbon atoms) A methacrylic acid alkyl ester in which the alkyl group has 1 to 8 carbon atoms or a vinyl yarn that can be copolymerized with the above-mentioned raw monomer, such as vinyl acetate, acrylonitrile. ,styrene,
Includes acrylamide', methyl methacrylate, etc.

(C) Functional group-containing monomer (0 to 10 parts by weight) above (Δ
), a functional group-containing monomer copolymerizable with (B),
For example, methacrylic acid.

These include acrylic acid, itaconic acid, hydroxyethyl methacrylate, hydroxypropyl methacrylate, trimethylaminoethyl methacrylate, acrylamide, methylol acrylamide, glycidyl methacrylate dimaleic anhydride, and the like.

For example, IJi's acrylic emulsions include:
Nikazole PL-3 manufactured by Nippon Carbide Industries Co., Ltd.
0OOA, C1,-302, CL-303, MG-
834, MG-1,439.

MG-230B, llX-78B,'A-02,A
-10,FX-347゜RX-629,S -3,00
1, TS-444, TS-582, TS-660.

There are TS-662, TS-530, TS-517B, etc.

Among these, the one that is particularly used as the acrylic emulsion in the present invention is nicazole A-1.
0 and nicazole S-3001. In the present invention, both of these are particularly used as polyvinyl acetate partially vulcanized products such as Gohsenol Old 1-17 manufactured by Nippon Gohsei Chemical Industry Co., Ltd.
(saponification degree 78.5 to 81.5 mol%) and (71) can significantly increase the adhesive strength as a glue compared to the case of using Kl+-17 alone.
It is desirable because it provides a sizing agent with little 11 residue and well-balanced physical properties.

Particularly unexpectedly, partially saponified polyvinyl acetate and these acrylic emulsion nicazole S-3
When 001 or 8 to 10 are used together, polyvinyl "r"
Significantly reduces or suppresses the occurrence of optical distortion due to mekkrylic slope during heating and stretching due to partially saponified acetate °C
It became clear that it was possible.

Among them, Nikazole S-3001 seems to be emulsion polymerized with 2-ethylhexyl acrylate as a main component and hinyl acetate as a comonomer, based on its spectroscopic data. It is particularly effective when used as a system emulsion. That is, when this emulsion of Nikabul S-3001 is used alone as a glue, the adhesive strength is too strong and the protective paper cannot be peeled off from the acrylic resin board, or the protective paper is torn. When added from 1 to 200% by weight (e.g., 133% by weight) in terms of solid content based on the solid content of partially saponified polyvinyl acetate, a stable emulsion paste is formed and has a suitable adhesive strength without any adhesive residue. This provides an excellent adhesive with little optical distortion and no practical problems.

The mixing ratio of the acrylic emulsion and the partially saponified polyvinyl acetate depends on the type of emulsion used and the physical properties of the glue, such as the adhesive strength required for the final glue, but the ratio of acrylic to the solid content of the partially saponified polyvinyl acetate depends The solid content ratio of the system emulsion is 1 to 200
It is 5% to 100% by weight, preferably 5 to 100% by weight. 1% by weight
If the amount is less than 200% by weight, the effect of adding the acrylic emulsion will hardly be recognized, and if it is more than 200% by weight, the adhesive force will be too strong and the protective saw 1 will be used when removing the protective sheet.
This is not practical because it may cause damage or leave a large amount of adhesive on the methacrylic resin plate. The mixing ratio of the acrylic emulsion and partially saponified polyvinyl acetate is
Considering the physical properties of the glue, it is possible to make any changes within the above range. It is necessary to select the type of acrylic emulsion and determine the amount to be used so as not to cause damage.

The boron compound used in the present invention is effective for preventing roughening and/or cranking of the bent portion of the heating wire.

Although the mechanism by which the addition of the I-toron compound prevents rough skin and/or thalassoking is not clear, the occurrence of rough skin and/or cranking is caused by the melting of the water-soluble adhesive during heating, which causes the fibers constituting the protective sheet to It is thought that this is achieved by the sizing itself being fused to the synthetic resin board, and the addition of a boron compound causes a crosslinking reaction between it and the partially saponified polyvinyl acetate when heated, resulting in rough skin and/or It is thought that the occurrence of cranking is suppressed.

Examples of the boron compound include boric acid diperborate, and an organic boron compound having a semipolar bond represented by the following formula, which is commercially available from Toho Chemical Industry Co., Ltd. under the name Emulbon GB, is also effective. .

The amount of the boron compound added varies depending on the type of partially saponified polyvinyl acetate and acrylic emulsion used at the same time, as well as the type of boron compound used, but is generally 0.01 to 20% based on the solid content of partially saponified polyvinyl acetate. The range is by weight%. 0.01
If it is less than % by weight, the effect of preventing skin roughness and/or crack-7 king due to its addition is poor. In addition, if the amount exceeds 20% by weight, there is almost no effect on preventing rough skin and/or thalassoking commensurate with the amount added, so there is no economic advantage. It becomes difficult to apply the adhesive to the resin plate, and the adhesive residue also worsens.

The above adhesive composition, which is an adhesive agent used in the present invention, includes [jJ plasticizer, moisture absorbent, preservative, thickener.

Antifoaming agents and the like can be added. The viscosity of this glue is desirably within the range of 200 to io, 00 centipoise (cp) for application purposes. Viscosity is 200
If it is lower than cp, stains consisting of adhesive agent residues and paper fiber fragments are likely to occur on the methacrylic resin plate when the protective sheet is removed. If the viscosity is greater than 10,000 cp, it will be difficult to apply uniformly, which is undesirable from the viewpoint of workability.

The coating amount of the glue used in the present invention is 0.4 to 1
0 g/td, preferably 0.6-2 g/td
rd range. 0.4 g/r+ (If it is less than that, adhesive residue will be left on the synthetic resin board when the protective sheet is removed from the methacrylic resin board or other synthetic resin board. Conversely,
If it exceeds 10 g/nr, defects such as rough skin may occur on the surface of the synthetic resin board, and the reproducibility of adhesive strength may become poor.

The adhesive can be applied by applying the adhesive evenly to the synthetic resin board and then attaching the protective sheet, or applying the adhesive to the protective sheet and then attaching it to the synthetic resin plate, or both. Examples include:

The synthetic resin that can be protected with the protective sheet using the adhesive of the present invention is not particularly limited as long as it can be pasted with the protective sheet, such as plate-shaped objects, cylindrical objects, semi-cylindrical objects, etc.
Various molded products such as rectangular shapes can be mentioned.

Examples of synthetic resin materials for forming these synthetic resin molded products include polymethyl methacrylate.

and other methacrylic resins, rubber-modified acrylic resins, polycarbonates, and polystyrene resins.

Examples include AS resin, ABS resin, vinyl chloride resin, acetate resin, and polyethylene resin. The adhesive for protective sheets of the present invention is particularly effective against bolimec acrylate, other methacrylic resins, and polycarbonate resins that have poor optical properties.

In the present invention, "C methacrylic resin plate" refers to polymethyl methacrylate having a viscosity average degree of polymerization of 800 to 8,000 or a copolymer resin containing methyl methacrylate as a main component.

Is paper, film, etc. used as the protective sheet?
Particularly preferred is a surface-smoothed krat paper with a density of 20 to 80 g/rd and similar materials. J.I.
Steckicht size degree power month () described in S P 8122
More than a second 1. The paper described in II3118129 preferably has a surface strength of 10 or more, but is not limited to this. Alternatively, coated paper coated with a thermoplastic resin on the surface not in contact with the methacrylic resin 1, or paper laminated with a thermoplastic film of -1 or more may be used.

(F) Effects of the Invention By adding an acrylic emulsion to the aqueous solution of the saponified polyvinyl acetate part, it becomes possible to obtain a strong adhesive force that could not be obtained with the saponified polyvinyl acetate part alone. As a result, cutting and
This eliminates peeling of edges during storage, transportation, and processing, so even if the protective sheet is removed, the surface of the synthetic resin board remains intact.
There are no more pressure scratches caused by IQ cracks or chips.

In addition, this eliminates the need to clean the surface of the synthetic resin board before applying heat molding or printing to the methacrylic resin board, and there is no risk of accidentally damaging the surface of the synthetic resin board during cleaning. Furthermore, another effect of the added acrylic emulsion was that the optical distortion of the methacrylic resin plate caused by the partially saponified polyhinyl acetate sizing agent during heating and stretching was reduced or suppressed.Furthermore, The added boron compound can prevent methacrylic 43 (fingerboard roughness and/or taranoking) caused by the glue during the heating wire bending process. The appearance of the bent part is no longer spoiled even when the bending is done.

(G) Examples Next, the present invention will be explained with reference to Examples and Comparative Examples. The embodiments merely show one example of the present invention, and the present invention is not limited thereto in any way.

Note that the evaluation 1i [1i results described in Examples were obtained by the method shown below.

Glue M: If the glue contains only water-soluble components and no water-insoluble components, cut the adhesive protective sheet peeled off from the synthetic resin board into 10cm x 10cm pieces and heat it at 100°C first.
Dry for 2 hours and weigh (weight in Wlg). Next, the test piece is placed in warm water at about 40°C, and after the glue is eluted for about 2 hours, it is similarly dried and weighed (the weight is W2 g). The amount of glue is calculated using the following formula.

Glue Wk (g/nf) = (W+ -1d2) x1
If the 00 glue contains water-insoluble components, it is impossible to accurately measure the amount of glue using the water elution method described above, so dry the protective sheet at 100°C for 2 hours before applying the glue and then weigh it. The weight is set to 2. ), then dry the adhesive protective sheet coated with adhesive in the same manner and weigh it to give a weight of -1. ), the amount of glue is calculated using the following formula.

Glue II (g/m) - (1'-night') x 100 Adhesion of protective sheet A synthetic resin plate specimen with a medium IQcm and a length of 3Qcm, with a protective sheet attached, was placed in a thermostatic chamber at a temperature of 23°C for 2 hours. After allowing the specimen to stand for more than 10 minutes, the adhesive strength was determined by the average force (in g/10cm) required to keep the protective sheet from peeling off from one end of the specimen at a speed of 30c+n/min, parallel to the synthetic resin plate and at a constant angle of 180°. year,
It is shown as the average value of 5 test pieces.

Adhesive residue: After the protective sheet was removed, the contamination state of the surface of the synthetic resin board was visually judged and classified into the following ranks.

Below margin Rank status △ Adhesive residue was clearly observed, and cleaning was required. There is a need for

Rough skin or cranking protection sheet when bending heating wire 1
The length and width of the surface protected by ~ is 3 (1 cm x 1
A synthetic resin plate of 5c+n is brought into contact with a heated rod-shaped heater for a certain period of time, then immediately bent at a 90° angle with the heating side facing outward, and the roughness or cranking that occurs at the bent part is visually judged and classified into the following ranks. did.

Rank status × The surface of the resin board is rough and crunchy. There are some occurrences of

Optical distortion: A protective sheet was immediately attached to the sheet after it was made, and after being left at room temperature for 3 days, it was blow-molded into a hemispherical shape with a diameter of 20 cm and a height of 10 cm. The grid lines were seen through this hemisphere, and the total extent of the grid lines was determined and classified into the following ranks.

rank status desire Example 1 Methyl methacrylate Shilonov with a polymerization rate of 19%.

(viscosity approximately 10 poise, 20'C), a mixture of a polymerization initiator Abhis dimethylvaleronitrile eooppm and a release agent dioctyl sulfosacunate 20p9m was used as a starting material and cast into a stainless steel plate with a thickness of 3 ms. The mixture was poured into a cell for 30 minutes at a temperature of 80°C, and then kept in an air bath at 120°C for 1 hour to produce a methacrylic resin plate with a thickness of 3 fins.

Next, to 80 parts by weight of a 9.5% by weight aqueous solution of partially saponified polyvinyl acetate Gohsenol (IUJ mark) K11-17 (Nippon Gosei Kagaku Kogyo Co., Ltd.!!) was added acrylic emulsion nicazole S-3001 (B). This Carheit Industrial Co., Ltd. formal wear has a solid content of 44.7% by weight.

Viscosity: 8900 cps) 20 parts by weight were added. The ratio of the solid content of Nikazole S-3001 to the solid content of partially saponified polyvinyl acetate in this aqueous solution is 118
It was a heavy foot%. Furthermore, Emulpon GB-90 (manufactured by Toho Chemical Co., Ltd., boron compound Emulpon GB with 10% water added) was added so that the solid content of partially saponified polyvinyl acetate in this aqueous solution was 5% by weight. A sizing agent of the present invention was prepared by adding . This was applied uniformly to the methacrylic resin board at a rate of 1.4 g/rt using a #8 bar coater.
/nr, Steckchtseiss degree 12 seconds 2 surface strength 12A)
was attached to obtain a methacrylic resin plate with a protected surface.

After this methacrylic resin plate with the protective paper was left in a constant temperature room at 23° C. overnight, the physical properties of the glue were measured according to the method described above, and the adhesive strength of the protective paper was measured. The results are shown in Table 1.

Comparative Example 1 A methacrylic resin board with a protective paper was produced in the same manner as in Example 1, except that acrylic emulsion Nikazole S-3001 and Emulpon (iB-90) were not added to the aqueous glue solution in the Example process. The adhesive was evaluated in exactly the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 2 All the procedures in Example 1 were repeated except that the acrylic emulsion nicazole 573001 was not added to the aqueous glue solution.
A methacrylic resin plate with protective paper was manufactured in the same manner as above,
The adhesive was evaluated in exactly the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 3 A methacrylic resin board with a protective paper was produced in the same manner as in Example 1, except that Emulpon GB-90 was not added to the aqueous adhesive solution in Example 1.
An evaluation of M1 agent was conducted. The results are shown in Table 1.

By comparing Margin Example 1 and Comparative Examples 1 to 3 below, the effect of using the adhesive of the present invention is clear. However, when comparing Example 1 and Comparative Example 1, it is found that the adhesive strength of the adhesive of the present invention is greater when the adhesive of the present invention is used than when only partially saponified polyvinyl acetate is used as the adhesive. Not only does it improve polyhinyl acetate-1
・Occurrence of optical distortion during blow molding, which is a defect of partially saponified adhesive, and heater cracking (rough skin and light from thalassogging during 1st bending)1. It turns out that this can be prevented.

In addition, by comparing Example 1 and Comparative Example 2, it was found that the addition of acrylic emulsion nicazole S-3001 greatly improved the adhesive strength of the glue, and
It can be seen that the effect of the surfactant present therein suppresses the occurrence of optical distortion during blow molding, which is a defect specific to partially saponified polyvinyl acetate pastes. Further, by comparing Example 1 and Comparative Example 3, it can be seen that the addition of the boron compound Emulbon GB-90 can prevent rough skin and thalassoking at the heater-heated bent portion.

Example 2 830 ppm of azobisdimethylvaleronitrile as a polymerization initiator was added to methyl methacrylate Shilonobu (viscosity: about 10 boas, 20°C) with a polymerization rate of 19%.

A mixture of 20 ppm of disulfosuccinate and disulfosuccinate as a release agent was used as a starting material, poured into a cast molding cell made of stainless steel plate with a thickness of 3 am, and heated to a temperature of 74:9.
0 minutes, then left in an air bath at 120°C for 1 hour to form a layer with a thickness of 3
A methacrylic resin plate of mm was manufactured.

Next, 85 parts by weight of an 8.0% by weight aqueous solution of Gohsenol Kli, 17 (trade name, manufactured by Honsei Kagaku Kogyo Co., Ltd.) as a partially saponified polyvinyl acetate product was added to 85 parts by weight of an 8.0% by weight aqueous solution of Gohsenol Kli, 17 (trade name, manufactured by Honsei Kagaku Kogyo Co., Ltd.), and an acrylic product made by Hon Carbide Kogyo Co., Ltd., solid content: 44.7 weight%.

Viscosity: 8900 cps) 15 parts by weight of Emulpon GB were added so that the proportion of the solid content of partially saponified polyvinyl acetate in this aqueous solution was 3% by weight.
-90 (manufactured by Toho Chemical Industry Co., Ltd., this is a nitrogen compound emalbon GB with 10% water added) to prepare the sizing agent of the present invention, and this was mixed using #8 Percoke. The above-mentioned methacrylic resin plate was coated with G evenly, and then Katatsuya kraft paper (made by Chiruko Daioh W1) was applied.
A methacrylic resin plate with a protected surface was obtained by pasting and suspending a tsubo ffi of 40 g/n (Stekcht scale: 12 seconds, surface strength: 12 A).

The methacrylic resin plate as an example of protective paper was left overnight in a constant temperature room at 23°C, and the physical properties of the glue were measured according to Method G described above. As a result, the adhesive force G was 35 g/♂, there was no adhesive residue, and the optical distortion was small, which was not a problem for practical use.

Example 3 In Example 1, cosenol had a concentration of ++-17';
All except that r7 and 0% (Same as Example 1)
A methacrylic resin plate with a protective paper was produced, and the adhesive was evaluated in exactly the same manner as in Example 1. The viscosity of the B-based glue (measured with a B-type viscometer at 20°C) is 2560 centipoise (cp), and its adhesive strength is 40 g.
/n(-ζ), no adhesive residue was observed, and optical distortion was at a level that caused no practical problems.

As is clear from the above, when the adhesive composition of the present invention is used, it is possible to prevent the occurrence of optical distortion peculiar to conventional partially saponified polyvinyl acetate products, as well as the occurrence of rough skin and crack knocking during heating and bending with a G heater. It can be prevented and the adhesion strength can be improved. From these results, the superiority of treating polymethyl methacrylate resin whose surface is protected using the adhesive of the present invention is clear.

Example 4 A plate of 3 mm thick extrusion or injection molding made of millicarbonate, As resin, A B 3 4!4 resin, polyhinyl chloride resin, acetate resin, and polystyrene resin was used in Example 1. Protective paper and DC tlJ
When bonded using Agent I, the adhesive strength was sufficient in all cases, and there was no adhesive residue on the surface of the board when it was peeled off.

Claims (1)

[Scope of Claims] (1) An aqueous solution containing 3 to 15% by volume of partially saponified polyvinyl acetate, the ratio of the solid content to the solid content of the partially saponified polyvinyl acetate in the aqueous solution is 1 to 2.
A adhesive for a protective sheet comprising an acrylic emulsion having a concentration of 0.00 double stars and a boron compound having a proportion of 0.01 to 20% by weight based on the solid content of partially saponified polyvinyl acetate in the aqueous solution. 2. The sizing agent according to claim 1, which is an emulsion polymer obtained from an acrylic emulsion or an intermediate mixture containing 2-ethylhexyl acrylate-1 as a main component and vinyl acetate as a comonomer. 3. Claim 1 in which the boron compound is boric acid
11J1 punishment as stated in Section 11. 4. The sizing agent according to claim 1, which is a boron compound or a compound represented by
% by weight of an aqueous solution, the solid content of which is based on the solid content of partially saponified polyvinylacetate and ruacetate in the aqueous solution is 1
A glue consisting of an acrylic emulsion of ~200% by weight and a boron compound having a proportion of partially saponified polyvinyl acetate in the aqueous solution of 0.01 to 20% by weight based on the solid content is applied between the synthetic resin board and the protective sheet. Surface protection synthetic resin molded product interposed in 6. The synthetic resin molded article according to claim 5, wherein the acrylic emulsion is an emulsion polymer obtained from a monomer mixture containing 2-ethylhexyl acrylate-1 as a main component and vinyl acetate as a comonomer. . 7. Claim 5 in which the boron compound is boric acid
Synthetic resin molded products as described in section. 8. The synthetic resin molded article according to claim 5, wherein the boron compound is a compound represented by the following formula. 9. Any one of claims 5 to 8, wherein the protective sheet is kraft paper made mainly from kraft valves whose surface in contact with the synthetic resin plate has been smoothed at least.
Synthetic resin molded product described in Crab. 10. According to any one of claims 5 to 9, the adhesive has a viscosity in the range of 200 to 10,000 centipoise at 20°C when the synthetic resin plate and the protective sheet are bonded together. Synthetic resin molded products. 11. The synthetic resin plate has an average viscosity of 800 g, o
The synthetic resin molded article according to any one of claims 5 to 10, which is a methacrylic resin plate made of a polymer of methyl methacrylate-I. 12. The amount of glue interposed is 0.4 to 10 g/M
A synthetic resin molded article according to any one of claims 5 to 11, which falls within the scope of the following claims.