JP5030293B2 - Dustless paper - Google Patents

Description

  The present invention relates to a dust-free paper used in a clean environment such as a clean room, and in particular, a small amount of dust generation, and further, a resin impregnation such as blocking and contamination of a resin impregnation machine or a cutter when cutting dust-free paper. It relates to dust-free paper with less contamination of subsequent process equipment.

  Traditionally, in industries such as the semiconductor industry, pharmaceutical manufacturing industry, precision machinery industry, etc., in clean rooms that have been cleaned to a high level so that fine dust and dust do not cause defects in various equipment and products. Work is being done. In such a clean room, paper having a very small amount of dust generation called dust-free paper is used for applications such as recording paper and wrapping paper. As the characteristics of dust-free paper, it is most important that dust such as paper powder such as fine inorganic particles and pulp fibers does not occur when rubbing or tearing.

  As such dust-free paper, polyolefin-based or polystyrene-based synthetic paper has been used in many cases, but these synthetic papers are often inferior in heat resistance and difficult to use in heat roll fixing printers and copiers. In recent years, dust-free paper mainly composed of pulp has been developed. Dust-free paper with pulp as the main component is required from the viewpoint of heat resistance and writing ability. There has also been proposed a technique of impregnating a resin emulsion into a base paper containing as a main component.

As such a dust-free paper, JP-A-60-167996 (Patent Document 1) discloses a dust-free paper in which a polymer substance having a glass transition temperature of 0 ° C. or less is contained in the paper. Specifically, acrylic terpolymers, acrylate copolymers, and vinyl acetate-acrylic acid copolymers are disclosed as possible high molecular substances. JP-A-63-105199 (Patent Document 2) discloses a dust-free paper impregnated with a synthetic resin having a glass transition temperature of 0 ° C. or less and a hollow pigment, and polyacrylic acid can be used as a usable synthetic resin. An ester copolymer resin emulsion is disclosed. As disclosed in Patent Documents 1 and 2, when a base paper mainly composed of pulp is impregnated with an acrylic resin having a low glass transition temperature, the lower the glass transition temperature of the acrylic resin, the more dust is generated. The amount tends to be small.
JP-A-60-167996 (refer to claim 1 and table 1) JP 63-105199 A (refer to claim 1 and table 1)

  However, on the other hand, the lower the glass transition temperature of the acrylic resin to be impregnated, the easier it is to block when dustless paper is superimposed, and the resin impregnation machine and the cutter when cutting dustless paper become dirty, etc. In the processes after the resin impregnation, the process equipment tends to be contaminated. In particular, when an acrylic resin having a glass transition temperature of −25 ° C. or lower is impregnated, the tendency for blocking and contamination to increase as the glass transition temperature decreases, causing problems in handling and operability as dust-free paper. There was a problem.

  The present invention has been made in view of such problems, and the object of the present invention is that the amount of dust generation is small and blocking is difficult to occur, and a cutter used for cutting a resin impregnation machine or dust-free paper is used. It is an object of the present invention to provide a dust-free paper that can be used in a clean environment such as a clean room with little contamination of process equipment after impregnation with resin, such as dirt.

  Other objects and operational effects of the present invention will be easily understood by those skilled in the art by referring to the following description.

  In order to achieve the above object, the dust-free paper of the present invention is a dust-free paper obtained by impregnating a base paper mainly composed of pulp with an impregnating liquid containing an acrylic resin emulsion, and the acrylic resin emulsion comprises: Acrylic resin (A) having a glass transition temperature of −68 to −25 ° C. and an acrylic resin (B) having a glass transition temperature of 40 to 70 ° C., respectively, in a weight ratio in terms of solid content (A) : (B) = 55: 45 to 80:20 The impregnation liquid contains 5 to 40 parts by weight of polyvinyl alcohol with respect to 100 parts by weight of the acrylic resin emulsion, and the impregnation amount of the impregnation liquid is The solid content is 6 to 30 parts by weight per 100 parts by weight of pulp.

  Here, the amount of impregnation liquid impregnated into the base paper is calculated based on the difference in weight of the base paper before and after the impregnation liquid is impregnated and the amount of decrease in the impregnation liquid per unit time. When determining the amount of impregnation by the difference in weight before and after impregnation with the impregnation liquid, first measure the weight of the base paper before impregnation with the impregnation liquid, and after the impregnation liquid is impregnated and dried, the dust-free paper is the same. The weight difference before and after this is taken as the amount of impregnation liquid. Moreover, when calculating based on the reduction | decrease amount of an impregnating liquid, it calculates | requires as follows, for example. In the case of impregnating the impregnating liquid in the size press process, when 100 kg of pulp is used per hour to make dust-free paper, and the amount of reduction of the size press liquid is 10 kg, “the impregnating liquid impregnating amount is the pulp 100 10 parts by weight per part by weight ". Further, the amount of decrease can be obtained from the difference in flow rate of the impregnating liquid between the supply line and the discharge line. If the concentration of the size press solution is 20%, the impregnation amount of the impregnation solution is 2 parts by weight per 100 parts by weight of the pulp in terms of solid content.

  And according to such a structure, since glass transition temperature is low, it can be set as dust-free paper with few dust generation amounts by using comparatively soft and highly adhesive acrylic resin (A). Moreover, the acrylic resin (A) having a low glass transition temperature and the acrylic resin (B) having a low glass transition temperature are used together with an acrylic resin (B) that is relatively hard and has low adhesiveness because of a high glass transition temperature. Compared to the case where the resin (A) is used alone, blocking is less likely to occur and the dust-free paper is less contaminated with the process equipment after resin impregnation, such as dirt on the resin impregnation machine and cutter when cutting dust-free paper. It becomes possible.

  In a preferred embodiment of the present invention, the polyvinyl alcohol is desirably a partially saponified polyvinyl alcohol having a saponification degree of 85 to 95 mol%. According to such a configuration, by using partially saponified polyvinyl alcohol that has higher water solubility and lower film strength than completely saponified polyvinyl alcohol, blocking, when impregnating a resin impregnator or dust-free paper It becomes possible to make the dust-free paper with less contamination of the process equipment after the resin impregnation such as dirt on the cutter.

  In a preferred embodiment of the present invention, it is desirable that the impregnation liquid further contains 0.1 to 1 part by weight of a wax emulsion with respect to 100 parts by weight of the acrylic resin emulsion. According to such a configuration, the slipperiness of the surface of the dust-free paper is increased by adding the wax emulsion, so that blocking is less likely to occur, and after the resin impregnation such as dirt on the resin impregnation machine and the cutter when cutting the dust-free paper It becomes possible to make the dust-free paper with less contamination of the process equipment.

  According to the present invention, it is possible to obtain dust-free paper that generates less dust, is less susceptible to blocking, and has less contamination of process equipment after resin impregnation, such as dirt on a resin impregnation machine or cutter when cutting dust-free paper. It becomes.

  Furthermore, by making the polyvinyl alcohol into a partially saponified polyvinyl alcohol having a saponification degree of 85 to 95 mol%, blocking is less likely to occur, and after resin impregnation such as dirt on a resin impregnation machine or cutter when cutting dust-free paper It becomes possible to make the dust-free paper with less contamination of the process equipment.

  Furthermore, when the impregnating solution contains 0.1 to 1 part by weight of a wax emulsion with respect to 100 parts by weight of the acrylic resin emulsion, blocking is less likely to occur, and when the resin impregnator or dust-free paper is cut. It becomes possible to make dust-free paper with less contamination of the process equipment after resin impregnation such as dirt on the cutter.

  Hereinafter, preferred embodiments of the present invention will be described, but the present invention is not limited to the following descriptions.

  The applicant previously described that the acrylic resin (A) having a glass transition temperature in this range is relatively contained by adding the acrylic resin (A) having a glass transition temperature of −68 to −25 ° C. to the impregnating liquid. Because of its softness and high adhesiveness, it can reduce the amount of dust generated from dust-free paper, resulting in a dust-free paper with low dust generation that can be used suitably in a clean environment such as a clean room. I found out.

  However, when an acrylic resin having a glass transition temperature of −68 to −25 ° C. is used alone, there is a possibility that blocking and contamination are likely to occur due to the relatively soft nature and high adhesiveness. The inventor of the present application diligently studied this point, and as the acrylic resin, the acrylic resin (A) having a glass transition temperature of −68 to −25 ° C. and a glass that is relatively hard as the acrylic resin. Mixing and using acrylic resin (B) having a transition temperature of 40 to 70 ° C., and further blending polyvinyl alcohol to suppress blocking and contamination while maintaining high dust generation performance. Found that it would be possible.

  Here, when the glass transition temperature of the acrylic resin (A) is lower than −68 ° C., it is considered that the amount of dust generation becomes smaller due to the increase in the adhesiveness of the acrylic resin (A). As the temperature decreases, the occurrence of blocking and contamination increases. On the other hand, if the glass transition temperature of the acrylic resin (A) that is relatively soft is higher than −25 ° C., the amount of dust generation increases due to a decrease in the adhesiveness of the acrylic resin (A), and thus the clean room or the like. It cannot be a dust-free paper with high dust generation performance that can be used in a clean environment.

  According to the knowledge of the inventors, when a relatively soft acrylic resin (A) having a glass transition temperature of −68 ° C. is used, the glass transition temperature is 40 to 70 ° C. By using a certain acrylic resin (B) and polyvinyl alcohol, blocking and contamination could be suppressed to the extent that there was no practical problem. On the other hand, when an acrylic resin emulsion having a glass transition temperature lower than −68 ° C. is used as the relatively soft acrylic resin (A), an acrylic resin having a glass transition temperature of 40 to 70 ° C. Even when the resin (B) and polyvinyl alcohol are used, there is a high possibility that blocking and contamination cannot be suppressed to a practical level.

  The soft acrylic resin (A) used in the present invention is not particularly limited as long as the glass transition temperature is in the range of −68 to −25 ° C., and the acrylic ester polymer and the styrene-acrylic acid copolymer are not particularly limited. Polymers, vinyl acetate-acrylic acid copolymers, acrylic terpolymer emulsions, and the like can be used. Among them, acrylic resins having a glass transition temperature of −68 to −25 ° C. can be easily selected. An acid ester polymer is more preferable.

  As described above, in the dust-free paper of the present invention, the impregnating liquid has a glass transition temperature in order to suppress blocking and contamination of the process equipment after resin impregnation such as dirt on the cutter when cutting the dust-free paper. An appropriate amount of acrylic resin (B) at 40 to 70 ° C. is blended. By blending an appropriate amount of the acrylic resin (B) having a glass transition temperature in this range, it is possible to obtain a dust-free paper with less blocking and less equipment contamination while suppressing the dust generation amount. This is because the acrylic resin (B), which is hard, prevents the adhesiveness of the acrylic resin (A), which is soft, and blocking from the adhesiveness of the acrylic resin (A) when used as dust-free paper. This is presumed to be because the dirt on the cutter is suppressed when cutting dust-free paper. In the dust-free paper of the present invention, polyvinyl alcohol is blended in the impregnation liquid. However, when the hard acrylic resin (B) and polyvinyl alcohol are used in combination, blocking and dust-free paper are used compared to the case where each is used alone. Dirt of the cutter and the like when cutting is significantly suppressed.

  In the dust-free paper of the present invention, when the glass transition temperature of the acrylic resin (B) that is hard is lower than 40 ° C., the blocking suppression effect when the dust-free paper is used is not sufficient, and when the dust-free paper is cut The effect of preventing contamination of process equipment after resin impregnation, such as dirt on the cutter, becomes poor. On the other hand, when the glass transition temperature of the acrylic resin (B) is higher than 70 ° C., it is a harder acrylic resin, and although it has an effect of suppressing blocking and preventing contamination, it is tacky by the soft acrylic resin (A). There is a high possibility that advanced dust generation performance cannot be maintained. Acrylic resins tend to become harder as the glass transition temperature becomes higher. If an acrylic resin (B) that is too hard has a glass transition temperature that is too high, it contains a large amount of inorganic pigments and organic pigments. As in the case of making it, the causative substance that becomes dust is contained in the paper in a large amount, and the dust generation amount of the dust-free paper is likely to increase.

  The hard acrylic resin (B) used in the present invention is not particularly limited as long as the glass transition temperature is in the range of 40 to 70 ° C., and includes an acrylate polymer, a styrene-acrylic acid copolymer, A vinyl acetate-acrylic acid copolymer, an acrylic terpolymer emulsion or the like can be used, and among them, a styrene-acrylic acid copolymer can be easily selected from those having a glass transition temperature of 40 to 70 ° C. Coalescence is preferred.

  In the dust-free paper of the present invention, the blending ratio of the acrylic resin (A) having a glass transition temperature of −68 to −25 ° C. and the acrylic resin (B) having a glass transition temperature of 40 to 70 ° C. is respectively Acrylic resin (A): acrylic resin (B) = 55: 45 to 80:20 in terms of weight ratio in terms of solid content. When the blending ratio of the acrylic resin (A) is larger than this range, the adhesiveness due to the soft acrylic resin (A) increases too much, so that the blocking inhibitory effect when using dustless paper is not sufficient, The effect of preventing contamination of process equipment after resin impregnation, such as dirt on the cutter when cutting dust-free paper, becomes poor. On the other hand, if the blending ratio of the acrylic resin (A) is below this range, sufficient adhesiveness due to the soft acrylic resin (A) cannot be obtained, and the dust generation performance is high enough to be used in a clean room. There is a high possibility that it cannot be maintained.

  Next, polyvinyl alcohol will be described. In the dust-free paper of the present invention, 5 to 40 parts by weight of polyvinyl alcohol is blended in the impregnating liquid with respect to 100 parts by weight of the acrylic resin emulsion. Here, 100 parts by weight of the acrylic resin emulsion represents the total amount of the acrylic resin (A) and the acrylic resin (B). By blending polyvinyl alcohol into the impregnating solution, blocking is difficult to occur while suppressing the amount of dust generation, and there is little contamination of process equipment after resin impregnation, such as dirt on the cutter when cutting resin impregnating machines and dust-free paper. Dust-free paper can be obtained. Although the reason why blocking and contamination of equipment are suppressed by adding polyvinyl alcohol to the impregnating solution is not clear, the adhesiveness of acrylic resin is suppressed by adsorbing polyvinyl alcohol on acrylic resin in a protective colloidal form. Thus, blocking and contamination of the cutter can be prevented, and since the hydration property of the acrylic resin is improved, it is presumed that contamination of process equipment such as a resin impregnator can be prevented.

  In the dust-free paper of the present invention, when the blending amount of polyvinyl alcohol in the impregnating liquid is less than 5 parts by weight with respect to 100 parts by weight of the acrylic resin emulsion, blocking of the dust-free paper cannot be suppressed, and a resin impregnator or dust-free paper can be used. The effect of preventing contamination of process equipment after resin impregnation, such as dirt on the cutter when cutting, is poor. In particular, since the effect of improving the hydration property of the acrylic resin becomes poor, it becomes impossible to sufficiently prevent contamination of process equipment such as a resin impregnator. On the other hand, if the blending amount of polyvinyl alcohol in the impregnating liquid exceeds 40 parts by weight with respect to 100 parts by weight of the acrylic resin emulsion, the blending amount of the acrylic resin emulsion (A) becomes relatively small, and the dust-free paper is discharged. The amount of dust increases, and it cannot be made dust-free paper with high dust generation performance that can be used in clean rooms.

  In the dust-free paper of the present invention, the impregnation amount of the impregnating liquid into the base paper is 6 to 30 parts by weight in terms of solid content with respect to 100 parts by weight of pulp. If the amount of impregnation liquid impregnated into the base paper is less than 6 parts by weight with respect to 100 parts by weight of pulp, the amount of the acrylic resin emulsion (A) for suppressing the amount of dust generation will be insufficient, and dust generation of dust-free paper will occur. The amount of the dust increases, and it is impossible to obtain a dust-free paper having a high dust generation performance used in a clean environment such as a clean room. On the other hand, when the amount of the impregnation liquid impregnated into the base paper exceeds 30 parts by weight with respect to 100 parts by weight of the pulp, the amount of the acrylic resin emulsion (A) in the base paper becomes too large, so Cutter contamination is likely to occur when cutting dust paper. Furthermore, since the opacity and stiffness of the dust-free paper are reduced, it is difficult to handle the dust-free paper, and there is a possibility that writing and printing will be poor.

  In the dust-free paper of the present invention, the type of polyvinyl alcohol to be used is not particularly limited, and polyvinyl alcohol such as silanol modification, carboxyl group modification, acetoacetyl group modification, cation modification, and the like can be used.

  In the dust-free paper of the present invention, it is desirable to use partially saponified polyvinyl alcohol as the polyvinyl alcohol. Partially saponified polyvinyl alcohol is superior in adsorptivity to an acrylic resin as compared to fully saponified polyvinyl alcohol, and a more protective colloidal effect can be expected. Furthermore, since it has higher water solubility and lower coating strength than completely saponified polyvinyl alcohol, adhesion of the impregnating liquid to process equipment such as a resin impregnator can be reduced. Therefore, by using partially saponified polyvinyl alcohol, blocking is less likely to occur, and contamination of process equipment after resin impregnation can be suppressed. Here, the saponification degree of the partially saponified polyvinyl alcohol is not particularly limited, but the saponification degree is preferably in the range of 85 to 95 mol%, and preferably used in the range of 86 to 89 mol%. Possible and more preferred.

  The impregnating liquid used for the dust-free paper of the present invention preferably contains 0.1 to 1 part by weight of the wax emulsion with respect to 100 parts by weight of the acrylic resin emulsion. By containing a small amount of wax emulsion, contamination of the process equipment after resin impregnation can be further reduced due to the slipperiness of the wax. If the blending amount of the wax emulsion is less than 0.1 parts by weight with respect to 100 parts by weight of the acrylic resin emulsion, the effect of suppressing contamination of process equipment by the wax cannot be sufficiently obtained. On the other hand, if it exceeds 1 part by weight with respect to 100 parts by weight of the acrylic resin emulsion, there is a risk that the writing accuracy with an aqueous pen or the like may be impaired. There may be a problem in running performance.

  In the present invention, known additives can be appropriately used in the impregnating liquid as long as the intended effects are not impaired. Examples of these additives include thickeners, dispersants, antifoaming agents, pH adjusters, surfactants, and the like. Further, an inkjet ink fixing agent may be used in order to impart printing suitability by inkjet.

  In the dust-free paper of the present invention, the method for impregnating the base paper with the impregnating liquid is not particularly limited, and a known impregnation method generally used in the papermaking field can be appropriately used. For example, an on-machine size press method, an off-machine dipping impregnation method, and an impregnation method using various coating machines can be used.

  In the dust-free paper of the present invention, the pulp used for the base paper is not particularly limited, and one or more known wood pulps can be appropriately selected and used. For example, chemical pulp NBKP, LBKP, SCP, etc., mechanical pulp GP, CGP, RGP, TMP, etc., deinked pulp, regenerated pulp, etc., pulp that has been broken up from the waste paper generated in the process may be used. .

  In the base paper used for the dust-free paper of the present invention, it is desirable not to add fillers that cause dust generation as much as possible in order to suppress the amount of dust generation, but it is necessary to add fillers unavoidably to improve opacity etc. If present, the amount added is preferably 3% by weight or less. When the filler exceeds 3% by weight, the amount of dust generation is remarkably increased, so that it is difficult to obtain a dust-free paper that can be used in a clean environment such as a clean room. When using a filler in the present application, it is possible to use a known filler that is usually used for papermaking. If the purpose is to improve opacity, blend titanium oxide that is effective even with a small amount of addition. Is desirable.

  Moreover, the well-known additive normally used for papermaking can be suitably used for the base paper used for dust-free paper in this application in the range which does not impair the target effect. These additives include sizing agents, dry paper strength enhancers, wet paper strength enhancers, yield improvers, dyes, pigments, antifoaming agents, pH adjusters, and the like.

  Examples of the dust-free paper according to the present invention will be specifically described below, but the present invention is not limited thereto. In addition, unless otherwise indicated, the part and% in an Example show a dry weight part and weight%.

<Example 1>
After 70 parts by weight of LBKP and 30 parts by weight of NBKP were used, the freeness was adjusted to 460 ml: CSF, and then 100 parts by weight of pulp dispersed in water, 0.3 parts by weight of sulfuric acid band, polyamide epoxy resin (Sumirez Resin 6615 / Sumitomo Chemical) Kogyo Co., Ltd.) 0.5 parts by weight was added to obtain a papermaking raw material for the base paper. Next, an acrylic ester copolymer (New Coat SFK-1000A · K5 / manufactured by Shin-Nakamura Chemical Co., Ltd.) having a glass transition temperature of −52 ° C. as a relatively soft acrylic resin (A) 70 30 parts by weight of an acrylic copolymer (Cybinol X-507-631E / Syden Chemical Co., Ltd.) having a glass transition temperature of 60 ° C. as a relatively hard acrylic resin (B), completely saponified 20 parts by weight of type polyvinyl alcohol (JF-17 / Nippon Vinegar & Poval Co., Ltd.) was dispersed in water to obtain an impregnation solution. Using the obtained papermaking raw material, a base paper was made with a paper machine, and in the paper making process, 15 parts by weight of an impregnating solution in terms of solid content was adhered to 100 parts by weight of the pulp of the base paper using a size press apparatus. Thereafter, calendar processing was performed at a calendar pressure of 25 kg / cm to obtain a target dust-free paper. The basis weight of the obtained dust-free paper was 74 g / m ² .

<Example 2>
In Example 1, instead of the acrylic ester copolymer (New Coat SFK-1000A / K5 / manufactured by Shin-Nakamura Chemical Co., Ltd.) having a glass transition temperature of −52 ° C., the glass transition temperature is −25 ° C. A dust-free paper was obtained in the same manner as in Example 1 except that a vinyl acetate-acrylic acid copolymer (Cybinol ACF-10 / manufactured by Seiden Chemical Co., Ltd.) was used.

<Example 3>
In Example 1, instead of the acrylic ester copolymer (New Coat SFK-1000A / K5 / manufactured by Shin-Nakamura Chemical Co., Ltd.) having a glass transition temperature of −52 ° C., the glass transition temperature is −68 ° C. A dust-free paper was obtained in the same manner as in Example 1 except that an acrylic ester copolymer (Newcoat SFK-1000C / S1 / manufactured by Shin-Nakamura Chemical Co., Ltd.) was used.

<Example 4>
In Example 1, a styrene-acrylic acid copolymer having a glass transition temperature of 40 ° C. instead of an acrylic copolymer having a glass transition temperature of 60 ° C. (Sybinol X-507-631E / manufactured by Seiden Chemical Co., Ltd.) Dust-free paper was obtained in the same manner as in Example 1 except that (Cybinol EK-81 / Saiden Chemical Co., Ltd.) was used.

<Example 5>
In Example 1, a styrene-acrylic acid copolymer having a glass transition temperature of 70 ° C. instead of an acrylic copolymer having a glass transition temperature of 60 ° C. (Cybinol X-507-631E / manufactured by Seiden Chemical Co., Ltd.) A dust-free paper was obtained in the same manner as in Example 1 except that (John Crill 61J / Johnson Polymer Co., Ltd.) was used.

<Example 6>
In Example 1, the blending amount of an acrylic ester copolymer (Newcoat SFK-1000A · K5 / manufactured by Shin-Nakamura Chemical Co., Ltd.) having a glass transition temperature of −52 ° C. is 80 parts by weight, and the glass transition temperature is 60. A dust-free paper was obtained in the same manner as in Example 1 except that the blending amount of the acrylic copolymer (Cybinol X-507-631E / Syden Chemical Co., Ltd.) at 20 ° C. was 20 parts by weight.

<Example 7>
In Example 1, 55 parts by weight of an acrylic acid ester copolymer (New Coat SFK-1000A · K5 / manufactured by Shin-Nakamura Chemical Co., Ltd.) having a glass transition temperature of −52 ° C. and a glass transition temperature of 60 are used. A dust-free paper was obtained in the same manner as in Example 1 except that the amount of the acrylic copolymer (Cybinol X-507-631E / manufactured by Seiden Chemical Co., Ltd.) at 45 ° C. was 45 parts by weight.

<Example 8>
In Example 1, a dust-free paper was obtained in the same manner as in Example 1 except that the blending amount of the completely saponified polyvinyl alcohol (JF-17 / Nippon Vinegar Poval Co., Ltd.) was 5 parts by weight.

<Example 9>
In Example 1, dust-free paper was obtained in the same manner as in Example 1 except that the blending amount of the fully saponified polyvinyl alcohol (JF-17 / Nippon Vinegar Poval Co., Ltd.) was 40 parts by weight.

<Example 10>
In Example 1, a dust-free paper was obtained in the same manner as in Example 1 except that the impregnation amount of the impregnation liquid was 30 parts by weight with respect to 100 parts by weight of the pulp of the base paper.

<Example 11>
In Example 1, a dust-free paper was obtained in the same manner as in Example 1 except that the impregnation amount of the impregnation liquid was 6 parts by weight with respect to 100 parts by weight of the pulp of the base paper.

<Example 12>
In Example 1, instead of 70 parts by weight of an acrylic acid ester copolymer (New Coat SFK-1000A · K5 / Shin Nakamura Chemical Co., Ltd.) having a glass transition temperature of −52 ° C., the glass transition temperature is −68. Acrylic copolymer (Cybinol X-507-) having a glass transition temperature of 60 ° C. using 80 parts by weight of an acrylic ester copolymer (Newcoat SFK-1000C / S1 / manufactured by Shin-Nakamura Chemical Co., Ltd.). Instead of 30 parts by weight of 631E / Syden Chemical Co., Ltd.), 20 parts by weight of a styrene-acrylic acid copolymer (Cybinol EK-81 / Syden Chemical Co., Ltd.) having a glass transition temperature of 40 ° C. is used. Amount of impregnated polyvinyl alcohol (JF-17 / Nippon Acetate / Poval) by 5 parts by weight Except that the 30 parts by weight to 100 parts by weight pulp base paper was obtained to dust-free paper in the same manner as in Example 1.

<Example 13>
In Example 1, instead of 70 parts by weight of an acrylic ester copolymer (New Coat SFK-1000A · K5 / manufactured by Shin-Nakamura Chemical Co., Ltd.) having a glass transition temperature of −52 ° C., the glass transition temperature is −25. Acrylic copolymer (Cybinol X-507-631E / Sidene) having a glass transition temperature of 60 ° C. using 55 parts by weight of a vinyl acetate-acrylic acid copolymer (Cybinol ACF-10 / manufactured by Seiden Chemical Co., Ltd.) Instead of 30 parts by weight, a saponified polyvinyl alcohol using 45 parts by weight of a styrene-acrylic acid copolymer (John Crill 61J / Johnson Polymer Co., Ltd.) having a glass transition temperature of 70 ° C. The blending amount of JF-17 / Nippon Vinegar-Poval Co., Ltd. is 40 parts by weight, and the impregnation amount of the impregnating liquid is the base paper Except that the 6 parts by weight per 100 parts by weight of pulp was obtained dust-free paper in the same manner as in Example 1.

<Example 14>
In Example 1, carboxy-modified polyvinyl alcohol (AT-17 /) having a saponification degree of 95.5 to 97.5 mol% instead of completely saponified polyvinyl alcohol (JF-17 / manufactured by NIPPON POV) A dust-free paper was obtained in the same manner as in Example 1 except that Nippon Vinegar Poval Co., Ltd. was used.

<Example 15>
In Example 1, instead of completely saponified polyvinyl alcohol (JF-17 / Nippon Vinegar & Poval), silanol-modified polyvinyl alcohol (R-1130 / Kuraray Co., Ltd.) having a saponification degree of 98 to 99 mol%. ) Was used in the same manner as in Example 1 except that dust-free paper was obtained.

<Example 16>
In Example 1, a partially saponified polyvinyl alcohol having a saponification degree of 86 to 89 mol% (Gosenol GL-03 / Japan) in place of the completely saponified polyvinyl alcohol (JF-17 / Nippon Vinegar Poval Co., Ltd.) Dust-free paper was obtained in the same manner as in Example 1 except that Synthetic Chemical Industry Co., Ltd. was used.

<Example 17>
In Example 1, a dust-free paper was obtained in the same manner as in Example 1 except that 0.1 part by weight of a wax emulsion (SN Coat 289 / San Nopco Co., Ltd.) was further blended in the impregnating solution.

<Example 18>
In Example 1, a dust-free paper was obtained in the same manner as in Example 1 except that 1 part by weight of a wax emulsion (SN coat 289 / manufactured by San Nopco Co., Ltd.) was further added to the impregnating solution.

<Example 19>
In Example 1, a partially saponified polyvinyl alcohol having a saponification degree of 86 to 89 mol% (Gosenol GL-03 / Japan) in place of the completely saponified polyvinyl alcohol (JF-17 / Nippon Vinegar Poval Co., Ltd.) A dust-free paper was obtained in the same manner as in Example 1 except that 0.5 part by weight of a wax emulsion (SN coat 289 / manufactured by San Nopco) was further blended in the impregnating solution.

<Comparative Example 1>
In Example 1, instead of an acrylic ester copolymer (New Coat SFK-1000A · K5 / Shin Nakamura Chemical Co., Ltd.) having a glass transition temperature of −52 ° C., the glass transition temperature is −12 ° C. A dust-free paper was obtained in the same manner as in Example 1 except that an acrylic ester copolymer (MT-2780SS / manufactured by Shin-Nakamura Chemical Co., Ltd.) was used.

<Comparative example 2>
In Example 1, a styrene-acrylic acid copolymer having a glass transition temperature of 24 ° C. instead of an acrylic copolymer having a glass transition temperature of 60 ° C. (Cybinol X-507-631E / manufactured by Seiden Chemical Co., Ltd.) A dust-free paper was obtained in the same manner as in Example 1 except that (Cibinol EK-61 / Syden Chemical Co., Ltd.) was used.

<Comparative Example 3>
In Example 1, a styrene-acrylic acid copolymer having a glass transition temperature of 96 ° C. instead of an acrylic copolymer having a glass transition temperature of 60 ° C. (Cybinol X-507-631E / manufactured by Seiden Chemical Co., Ltd.) A dust-free paper was obtained in the same manner as in Example 1 except that (Sybinol SK-202 / Siden Chemical Co., Ltd.) was used.

<Comparative example 4>
In Example 1, the blending amount of an acrylate copolymer having a glass transition temperature of −52 ° C. (Newcoat SFK-1000A · K5 / manufactured by Shin-Nakamura Chemical Co., Ltd.) was 90 parts by weight, and the glass transition temperature was 60. A dust-free paper was obtained in the same manner as in Example 1 except that the blending amount of the acrylic copolymer (Cybinol X-507-631E / Syden Chemical Co., Ltd.) at 10 ° C. was 10 parts by weight.

<Comparative Example 5>
In Example 1, 45 parts by weight of an acrylic acid ester copolymer (New Coat SFK-1000A · K5 / manufactured by Shin-Nakamura Chemical Co., Ltd.) having a glass transition temperature of −52 ° C. and a glass transition temperature of 60 are used. A dust-free paper was obtained in the same manner as in Example 1 except that the blending amount of the acrylic copolymer (Cybinol X-507-631E / Syden Chemical Co., Ltd.) at 55 ° C. was 55 parts by weight.

<Comparative Example 6>
In Example 1, a dust-free paper was obtained in the same manner as in Example 1 except that the blending amount of the completely saponified polyvinyl alcohol (JF-17 / Nihon Vinegar Poval Co., Ltd.) was changed to 3 parts by weight.

<Comparative Example 7>
In Example 1, a dust-free paper was obtained in the same manner as in Example 1 except that the blending amount of the completely saponified polyvinyl alcohol (JF-17 / Nihon Vinegard-Poval Co., Ltd.) was 50 parts by weight.

<Comparative Example 8>
In Example 1, a dust-free paper was obtained in the same manner as in Example 1 except that the impregnation amount of the impregnation liquid was 3 parts by weight with respect to 100 parts by weight of the pulp of the base paper.

<Comparative Example 9>
In Example 1, dust-free paper was obtained in the same manner as in Example 1 except that the impregnation amount of the impregnating liquid was 35 parts by weight with respect to 100 parts by weight of the pulp of the base paper.
The evaluation result about the dust-free paper obtained in Examples 1-19 and Comparative Examples 1-9 is shown in FIG. The dust generation amount, blocking, contamination evaluation method, and notation shown in the figure are as follows.

[Dust generation]
In accordance with SEMI G67-0996 “Measurement method of particles generated from sheet material”, a rubbing and tearing test is performed in a clean bench, and a particle diameter of 0.3 μm or more is measured using KR-12A (Rion particle counter). The number of particles was measured. The unit in the table is pieces / CF (number per cubic foot). The results of both the rubbing and tearing tests were comprehensively evaluated, and the four-level evaluation was performed with “excellent”, “good”, “good”, and “impossible” in order of decreasing dust generation.
Here, the clean bench has a 0.75m width x 0.5m depth x 0.7m height cuboid with a steel frame, and covers the front, back, left and right sides with a curtain made of vinyl chloride resin. A metal plate on which a CS-CUTE-05A type (manufactured by Seas Sea Co., Ltd.) was installed was used. The air outlet of the cleaner has a width of 0.58 m and a depth of 0.275 m, and the filter air outlet has a wind speed of 0.6 m / s.

Rubbing test: Prepare two A5 size test pieces whose paper flow direction (MD direction) is the short side, superimpose the front and back of the test piece, 1 in the direction perpendicular to the paper flow direction (CD direction). By rubbing by hand for 1 minute at a rate of 30 reciprocations per minute, the number of generated dust was measured.

Tear test: A4 size test piece whose paper flow direction (MD direction) is the long side is torn at 18 points per minute along the long side direction of the paper (the tear length is the long side of A4 size), The number of generated dust was measured.

[blocking]
250 A4 size test pieces were stacked, a 40 kg weight was placed, and 23 ° C. × 50% r.p. After 30 days under the condition of h, the degree of blocking was confirmed. A four-level evaluation was performed with ◎ Excellent, ○ Good, △ Yes, × Not OK in order from the least blocking.

[pollution]
The following two types of sensitivity tests were comprehensively evaluated, and the four-level evaluation was performed with “Excellent”, “Good”, “Good”, and “Not good” in order from the least contaminated.

Detergency sensitivity test: The presence or absence of dirt due to the impregnation liquid in the impregnation machine and the drying step after impregnation was confirmed.

Cutting sensitivity test: The test piece was cut with scissors having a blade length of about 7 cm, and this was repeated 300 times to confirm the dirt on the blade.

  As is clear from FIG. 1, the dust-free paper obtained in Examples 1 to 19 has a small amount of dust generation in both the rubbing and tearing tests, has a good level of blocking, and is free from contamination. there were. In the following, verification will be performed based on the dust-free paper obtained in Example 1. In each item, ◎, ○, and Δ are practically no problem, and × is a practical problem.

  First, it verifies about the glass transition temperature of the acrylic resin emulsion in an impregnation liquid. The dust-free paper obtained in Example 2 using an acrylic resin having a glass transition temperature of −25 ° C. as the relatively soft acrylic resin (A) is −52 ° C. as the acrylic resin (A). Although the amount of dust generation was slightly higher than the dust-free paper obtained in Example 1 using an acrylic resin, it was at a level where there was no practical problem. The dust-free paper obtained in Example 3 using an acrylic resin emulsion having a glass transition temperature of −68 ° C. as the relatively soft acrylic resin (A) is the same as the dust-free paper obtained in Example 1. Although blocking and contamination were somewhat observed in comparison, the level was satisfactory for practical use. On the other hand, the dust-free paper obtained in Comparative Example 1 using an acrylic resin having a glass transition temperature of −12 ° C. as the relatively soft acrylic resin (A) is the dust-free paper obtained in Example 1. The amount of generated dust is larger than that of the sewage and cannot be used in a clean environment such as a clean room. From the above, it is considered that the glass transition temperature of the relatively soft acrylic resin is preferably in the range of −68 to −25 ° C.

  The dust-free paper obtained in Example 4 using an acrylic resin having a glass transition temperature of 40 ° C. as a relatively hard acrylic resin is more resistant to blocking and dust-free paper than the dust-free paper obtained in Example 1. Although there was some contamination, it was at a level where there was no practical problem. The dust-free paper obtained in Example 5 using an acrylic resin having a glass transition temperature of 70 ° C. as a relatively hard acrylic resin is slightly more dust-generating than the dust-free paper obtained in Example 1. However, it was at a level where there was no practical problem. On the other hand, the dust-free paper obtained in Comparative Example 2 using an acrylic resin having a glass transition temperature of 24 ° C. as a relatively hard acrylic resin is more blocking than the dust-free paper obtained in Example 1. In addition, the resin is attached to the impregnation machine and the dryer in the drying process after impregnation, resulting in poor cleanability, and even in the evaluation of cutting properties, a large amount of dirt is seen on the blade, which can be put to practical use. It was not. The dust-free paper obtained in Comparative Example 3 using an acrylic resin having a glass transition temperature of 96 ° C. as a relatively hard acrylic resin has a dust generation amount as compared with the dust-free paper obtained in Example 1. It was not possible to use in a clean environment such as a clean room. From the above, it is considered that the glass transition temperature of the relatively rigid acrylic resin is preferably in the range of 40 to 70 ° C.

  Next, the mixing ratio of the relatively soft acrylic resin and the hard acrylic resin into the impregnating liquid is verified. The dust-free paper obtained in Example 6 in which the blending ratio of the relatively soft acrylic resin and the hard acrylic resin was 80:20 was compared with the dust-free paper obtained in Example 1. Although blocking and contamination were somewhat observed, it was at a level that was not a problem for practical use. The dust-free paper obtained in Example 7 in which the blending ratio of the relatively soft acrylic resin and the hard acrylic resin was 55:45 was more than the dust-free paper obtained in Example 1. Although the amount of dust was slightly increased, it was at a level where there was no practical problem. The dust-free paper obtained in Comparative Example 4 in which the blend ratio of the relatively soft acrylic resin and the hard acrylic resin was 90:10 was compared with the dust-free paper obtained in Example 1. As a result, blocking occurred remarkably. In addition, the resin is attached to the impregnation machine or the dryer in the drying process after the impregnation, resulting in poor cleanability. Even in the evaluation of the cutting property, a large amount of dirt is seen on the blade, which is not practical. It was. The dust-free paper obtained in Comparative Example 5 in which the blending ratio of the relatively soft acrylic resin and the hard acrylic resin was 45:55 was compared with the dust-free paper obtained in Example 1. As a result, the amount of dust generated increased and was not usable in a clean environment such as a clean room. From the above, it seems that the blending ratio of the relatively soft acrylic resin and the hard acrylic resin in the impregnating liquid is preferably in the range of 55:45 to 80:20.

  Next, it verifies about the addition amount of polyvinyl alcohol. In Example 1 in which 20 parts by weight of polyvinyl alcohol was added to 100 parts by weight of the acrylic resin emulsion, the amount of dust generation was small in both the rubbing and tearing tests, blocking was at a good level, and there was a problem with contamination. It was not. In Example 8 in which 5 parts by weight of polyvinyl alcohol was added to 100 parts by weight of the acrylic resin emulsion, blocking and contamination were slightly observed as compared with the dust-free paper obtained in Example 1, but there was no practical problem. It was a level. The dust-free paper obtained in Example 9 in which 40 parts by weight of polyvinyl alcohol was added with respect to 100 parts by weight of the acrylic resin emulsion had a slightly larger amount of dust generation than the dust-free paper obtained in Example 1. However, it was a level with no problem in practical use. In the dust-free paper obtained in Comparative Example 6 in which 3 parts by weight of polyvinyl alcohol was added to 100 parts by weight of the acrylic resin emulsion, blocking was significantly generated as compared with the dust-free paper obtained in Example 1. In addition, the resin is attached to the impregnation machine or the dryer in the drying process after the impregnation, resulting in poor cleanability. Even in the evaluation of the cutting property, a large amount of dirt is seen on the blade, which is not practical. It was. The dust-free paper obtained in Comparative Example 7 in which 50 parts by weight of polyvinyl alcohol is added with respect to 100 parts by weight of the acrylic resin emulsion has a larger dust generation amount than the dust-free paper obtained in Example 1, and the clean room. It was not usable in a clean environment such as. As mentioned above, it seems that the addition amount of polyvinyl alcohol is preferably in the range of 5 to 40 parts by weight with respect to 100 parts by weight of the acrylic resin emulsion.

  Next, the impregnation amount of the impregnation liquid is verified. The dust-free paper obtained in Example 10 in which 30 parts by weight of the impregnating liquid was impregnated with 100 parts by weight of the pulp of the base paper was slightly blocked as compared with the dust-free paper obtained in Example 1, and was cut. In the evaluation, although the blade was stained, it was at a level where there was no practical problem. The dust-free paper obtained in Example 11 in which 6 parts by weight of the impregnating liquid was impregnated with 100 parts by weight of the pulp of the base paper had a slightly larger amount of dust generation than the dust-free paper obtained in Example 1. However, it was a level with no problem in practical use. The dust-free paper obtained in Comparative Example 8 obtained by impregnating 3 parts by weight of the impregnating liquid with respect to 100 parts by weight of the pulp of the base paper has a larger dust generation amount than the dust-free paper obtained in Example 1, and the clean room. It was not usable in a clean environment such as. The dust-free paper obtained in Comparative Example 9 in which 35 parts by weight of the impregnating liquid was impregnated with 100 parts by weight of the pulp of the base paper was significantly blocked as compared with the dust-free paper obtained in Example 1, and was cut. In the evaluation of the property, a large amount of dirt was seen on the blade. In addition, there is a fear of see-through when printing with low opacity compared to the dust-free paper obtained in Examples 1 to 19, and handling is difficult due to low rigidity, so that writing with an aqueous pen or the like is appropriate. The printability was relatively poor. This seems to be because the impregnation amount of the impregnation liquid is too large. From the above, it is considered that the impregnation amount of the impregnation liquid is preferably 6 to 30 parts by weight with respect to 100 parts by weight of the pulp of the base paper in terms of solid content.

  Next, it verifies about the saponification degree of polyvinyl alcohol. The dust-free papers obtained in Examples 14 to 16 using partially saponified polyvinyl alcohol exhibited significant blocking and contamination prevention effects compared to the dust-free paper obtained in Example 1. In particular, the dust-free paper obtained in Example 16 using polyvinyl alcohol having a saponification degree of 86 to 89 mol% showed more remarkable blocking and contamination prevention effects than the dust-free paper obtained in Example 1. It was. From this, it seems that it is more preferable to use partially saponified polyvinyl alcohol as polyvinyl alcohol.

  Next, it verifies about the addition amount of a wax emulsion. Compared with the dust-free paper obtained in Example 1, the dust-free paper obtained in Example 17 to which 0.1 part by weight of the wax emulsion was added showed blocking and contamination prevention effects. The dust-free paper obtained in Example 18 to which 1.0 part by weight of the wax emulsion was added is similar to the dust-free paper obtained in Example 17, and blocking and contamination are prevented as compared with the dust-free paper obtained in Example 1. The effect was seen. From the above, it seems that the wax emulsion is preferably added in the range of 0.1 to 1.0 part by weight.

  Also, an acrylic resin emulsion having a glass transition temperature of −68 ° C. is used as an acrylic resin that is soft, and an acrylic resin having a glass transition temperature of 40 ° C. is used as a hard acrylic resin. The blending ratio of the acrylic resin that is hard and the acrylic resin that is hard is 80:20, 5 parts by weight of polyvinyl alcohol is added to 100 parts by weight of the acrylic resin emulsion, and the impregnation liquid is pulp of the base paper The dust-free paper obtained in Example 12 impregnated with 30 parts by weight with respect to 100 parts by weight showed the most blocking among Examples 1 to 19, and the blade was stained in the evaluation of cutting properties. It was a level that could withstand practical use. Also, an acrylic resin emulsion having a glass transition temperature of −25 ° C. is used as an acrylic resin that is soft, and an acrylic resin having a glass transition temperature of 70 ° C. is used as a hard acrylic resin. The mixing ratio of the acrylic resin and the hard acrylic resin is 55:45, 40 parts by weight of polyvinyl alcohol is added to 100 parts by weight of the acrylic resin emulsion, and the impregnating liquid is used as the pulp of the base paper. The dust-free paper obtained in Example 13 impregnated with 6 parts by weight with respect to 100 parts by weight had the highest dust generation amount among Examples 1 to 19, but was at a level that could withstand practical use.

  As described above, according to the present invention, the amount of dust generation is small, blocking is difficult to occur, and contamination of process equipment after resin impregnation such as dirt on a resin impregnation machine or cutter when cutting dustless paper is small. It is possible to obtain dust-free paper.

It is a graph which shows the evaluation result of an Example and a comparative example.

Claims (3)

A dust-free paper in which an impregnating liquid containing an acrylic resin emulsion is impregnated into a base paper mainly composed of pulp,
In the acrylic resin emulsion, an acrylic resin (A) having a glass transition temperature of −68 to −25 ° C. and an acrylic resin (B) having a glass transition temperature of 40 to 70 ° C. are converted into solids, respectively. In a weight ratio of (A) :( B) = 55: 45 to 80:20,
The impregnating liquid contains 5 to 40 parts by weight of polyvinyl alcohol with respect to 100 parts by weight of the acrylic resin emulsion, and the impregnating amount of the impregnating liquid is 6 to 30 parts by weight per 100 parts by weight of pulp in terms of solid content. Dust-free paper characterized by that.   The dust-free paper according to claim 1, wherein the polyvinyl alcohol is a partially saponified polyvinyl alcohol having a saponification degree of 85 to 95 mol%.   The dust-free paper according to claim 1 or 2, wherein the impregnating liquid further contains 0.1 to 1 part by weight of a wax emulsion with respect to 100 parts by weight of the acrylic resin emulsion.

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