KR20230142560A - Methacrylic resin composition for hot plate fusion, use of methacrylic resin composition for hot plate fusion in hot plate fusion, fusion method, and vehicle member - Google Patents

Abstract

Stringing is unlikely to occur when the resin composition is removed from the hot plate during hot plate fusion, and peeling residues of the resin composition are unlikely to occur on the mold surface during injection molding, that is, it is suitable for injection molding and hot plate fusion. A methacrylic resin composition is provided. The methacrylic resin composition for hot plate fusion of the present invention contains a methacrylic polymer and a fatty acid.

Description

Methacrylic resin composition for hot plate fusion, use of methacrylic resin composition for hot plate fusion in hot plate fusion, fusion method, and vehicle member

The present invention relates to a methacrylic resin composition for hot plate fusion, use of the methacrylic resin composition for hot plate fusion in hot plate fusion, a fusion method, and a vehicle member.

This application claims priority based on Patent Application No. 2021-036914 filed in Japan on March 9, 2021, and uses the content here.

Methacrylic resins, due to their excellent appearance, transparency, weather resistance, chemical resistance, etc., are used in vehicle members such as vehicle interior and exterior materials such as tail lamp covers, head lamp covers, and meter panels; architectural absence; It is used for many purposes, including as a member of household equipment such as washbasins, bathtubs, and flush toilets.

When methacrylic resin is used for these purposes, these members are bonded to a member containing a resin other than a styrene-based resin such as MS resin or ABS resin, or a methacrylic resin such as polycarbonate-based resin. , is processed. As a method for joining these members, a hot plate fusion method is known (Patent Documents 1 to 4).

The hot plate fusion method is a method of attaching the joint surface of each member to a metal hot plate, heating and melting it, retracting the hot plate, and then welding (pressing) it with another member until the resin cools and hardens. , high weld strength is obtained. In addition, the hot plate fusion method is a method with excellent productivity in that it is possible to weld large parts together, and has advantages such as eliminating the effort of applying adhesive and the time for curing the adhesive.

Japanese Patent Publication No. 2005-239823 Japanese Patent Publication No. 2009-249528 International Publication No. 2009/125766 Japanese Patent Publication No. 2009-249529

In the hot plate fusion method, the joint portion of each member can be melted in a short time by raising the hot plate temperature. However, if the heating plate temperature is too high, when each member is removed from the heating plate, some of the resin does not peel off easily from the heating plate, and a phenomenon of stretching into a thread shape (so-called stringing) is observed, damaging the appearance of the product. There is.

When the methacrylic resin composition disclosed in Patent Documents 1 to 4 is melted on a hot plate and then removed from the hot plate, some of the resin does not peel off easily from the hot plate, leading to stringing or damage to the mold during injection molding. When removing a molded body from a mold, there may be cases where resin remains on the surface of the mold (so-called peeling residue). In such cases, there are problems such as the appearance of the product being damaged due to the joining surface of the members becoming rough, or unnecessary cleaning work being required for the surface of the hot plate for hot plate fusion or the mold surface for injection molding.

The present invention aims to solve these problems. That is, the purpose of the present invention is to prevent stringing from occurring when removing the resin composition from the hot plate during hot plate fusion, and to prevent peeling residues of the resin composition from occurring on the mold surface during injection molding, that is, to prevent the formation of peeling residues of the resin composition on the mold surface during injection molding and hot plate. The object is to provide a methacrylic resin composition suitable for hot plate fusion.

As a result of repeated studies to solve the above problems, the present inventors have arrived at the present invention. That is, the present invention includes the following aspects.

[1] A methacrylic resin composition for hot plate fusion, comprising a methacrylic polymer and a fatty acid.

[2] The methacrylic resin composition for hot plate fusion of [1], wherein the fatty acid has 10 to 22 carbon atoms.

[3] The methacrylic resin composition for hot plate fusion of [1] or [2], wherein the 10% weight loss temperature of the fatty acid is 250°C or lower.

[4] The methacrylic resin composition for hot plate fusion according to any of [1] to [3], wherein the fatty acid has a melting point of 50°C or higher.

[5] The methacrylic resin composition for hot plate fusion according to any of [1] to [4], wherein the fatty acid is a chain hydrocarbon compound having at least one carboxyl group in the molecule.

[6] The methacrylic resin composition for hot plate fusion according to any of [1] to [5], wherein the fatty acid has a molecular weight of 100 to 500.

[7] The methacrylic resin composition for hot plate fusion according to any of [1] to [6], wherein the fatty acid content is 0.01 to 1 part by mass based on 100 parts by mass of the methacrylic polymer.

[8] The methacryl for hot plate fusion according to any of [1] to [6], wherein the fatty acid content is 0.01 to 1% by mass based on the total mass (100% by mass) of the methacrylic resin composition for hot plate fusion. Systemic resin composition.

[9] The methacrylic resin composition for hot plate fusion according to any of [1] to [8], wherein the fatty acid contains at least one selected from stearic acid, palmitic acid, and myristic acid.

[10] [1] to [, wherein the methacrylic polymer contains a repeating unit derived from methyl methacrylate, and the content ratio of the repeating unit derived from the methyl methacrylate in the methacrylic polymer is 70% by mass or more. The methacrylic resin composition for hot plate fusion according to any of [9].

[11] The methacrylic polymer is a polymer (A) containing a repeating unit derived from a (meth)acrylic acid ester monomer and a structural unit derived from a ring structure,

The structural unit derived from the ring structure contains at least one selected from the group consisting of a glutaric anhydride structural unit, a maleic anhydride structural unit, a glutarimide structural unit, a lactone ring structural unit, and an N-substituted maleimide structural unit. The methacrylic resin composition for hot plate fusion according to any of [1] to [10].

[12] The polymer (A) contains a repeating unit derived from methyl methacrylate (A1), a repeating unit derived from (meth)acrylic acid (A2), and a glutaric anhydride structural unit (A3), [11] Methacrylic resin composition for hot plate fusion.

[13] The methacrylic resin composition for hot plate fusion according to any of [1] to [12], which is used as a raw material for vehicle members.

[14] The methacrylic resin composition for hot plate fusion of [13], wherein the vehicle member is at least one type selected from a tail lamp cover, a head lamp cover, and a meter panel.

[15] Use of the methacrylic resin composition for hot plate fusion according to any of [1] to [14] in hot plate fusion.

[16] A process of melting at least a portion of the first member formed of the methacrylic resin composition for hot plate fusion according to any of [1] to [14] by contacting it with a hot plate;

A method of fusing a first member and a second member, comprising the step of removing the first member from the hot plate and pressing it with the second member.

[17] A vehicle member including a composite member formed by adhering a first member and a second member,

A vehicle member wherein the first member contains a methacrylic polymer and a fatty acid.

[18] A vehicle member including a composite member formed by adhering a first member and a second member,

A vehicle member, wherein the first member is a member formed of the methacrylic resin composition for hot plate fusion according to any of [1] to [14].

According to the present invention, stringing is unlikely to occur when the resin composition is removed from the hot plate during hot plate fusion, and peeling residues of the resin composition are unlikely to occur on the mold surface during injection molding, that is, during injection molding and hot plate fusion. A suitable methacrylic resin composition for hot plate fusion can be provided.

1 is a process diagram showing the hot plate fusion method according to this embodiment.
Figure 2(a) is a schematic diagram of a disk-shaped molded product used for evaluation of release properties as seen from the side. (b) A schematic diagram of a disc-shaped molded product used for evaluation of release properties as seen from the top.
Figure 3 is a schematic diagram of a cone-shaped test piece used to evaluate stringing properties as seen from the side.
Figure 4 is a schematic diagram showing a state in which a cone-shaped test piece is pulling the yarn in a stringing test.

In the present invention, “(meth)acrylate” means at least one selected from “acrylate” and “methacrylate”, and “(meth)acrylic acid” means “acrylic acid” and “methacrylic acid”. means at least one type selected from .

In the present invention, “monomer” means an unpolymerized compound, and “repeating unit” means a unit derived from a monomer formed by polymerization. The repeating unit may be a unit formed directly through a polymerization reaction, or a part of the unit may be converted into a separate structure by processing the polymer.

In the present invention, “mass%” represents the content ratio of a predetermined component contained in 100% by mass of the total amount.

In the present invention, “the obtained resin molded body” means a molded body obtained by molding a methacrylic resin composition for hot plate fusion.

In the present invention, the numerical range expressed using “to” means a range that includes the numerical values written before and after “to” as the lower limit and upper limit.

<Methacrylic resin composition for hot plate fusion>

The methacrylic resin composition for hot plate fusion (hereinafter, appropriately referred to as “methacrylic resin composition”) of the present invention contains a methacrylic polymer and a fatty acid.

The melt flow rate (MFR) of the methacrylic resin composition of the present invention is not particularly limited. Preferably, in accordance with ISO 1133-1:2011, the MFR measured under the conditions of a temperature of 230°C and a load of 3.8 kg is preferably 0.1 to 10 g/10 min, more preferably 0.2 to 5 g/10 min, and 0.3 to 0.3 g/10 min. 2g/10min is more preferable.

Since the MFR is below the above upper limit, the generation of bubbles, etc. during melting of the methacrylic resin composition in the hot plate fusion method is likely to be effectively suppressed. When the MFR is more than the above lower limit, the moldability of the methacrylic resin composition tends to be good.

In order to control the MFR to 0.1 to 10 g/10 min, for example, the composition ratio of the monomer unit can be controlled and the mass average molecular weight of the methacrylic polymer can be adjusted.

<Methacrylic polymer>

The methacrylic polymer in the present invention is a polymer containing a repeating unit derived from methyl methacrylate (hereinafter also referred to as “methyl methacrylate unit”) as a main component.

By containing a methacrylic polymer, the methacrylic resin composition of the present invention improves the transparency of the obtained resin molded body, suppresses thermal decomposition of the resin molded body, and improves weather resistance and moldability.

In the present invention, "containing methyl methacrylate unit as the main component" means, in one embodiment, that the content ratio of the methyl methacrylate unit in the methacrylic polymer (100 mass%) is 70 mass% or more.

As a methacrylic polymer, it is preferable that the content ratio of the methyl methacrylate unit in the methacrylic polymer (100 mass%) is 70 mass% or more. Such methacrylic polymers include, for example, a homopolymer of methyl methacrylate, 70% by mass or more but less than 100% by mass of methyl methacrylate units, and repeating units derived from monomers other than methyl methacrylate (hereinafter, “other monomers”) Also referred to as “unit.”) A copolymer containing more than 0% by mass and 30% by mass or less can be mentioned.

Monomers other than methyl methacrylate that form other monomer units are not particularly limited as long as they are monomers that can be copolymerized with methyl methacrylate. It may be a monofunctional monomer having one double bond capable of radical polymerization in one molecule, or it may be a polyfunctional monomer having two or more double bonds capable of radical polymerization in one molecule. From the viewpoint of excellent balance between the fluidity, moldability, and thermal decomposability of the methacrylic polymer, acrylic acid ester is preferable.

When the methacrylic polymer contains a repeating unit derived from acrylic acid ester (hereinafter also referred to as “acrylic acid ester unit”) as other monomer units, the methyl methacrylate unit is included in the methacrylic polymer (100% by mass). It is preferable to contain more than 70% by mass but less than 100% by mass and more than 0% by mass and less than 30% by mass of acrylic acid ester units, and more than 80% by mass and 99.9% by mass or less of methyl methacrylate units and 0.1% by mass or more of 20% by mass of acrylic acid ester units. It is more preferable to contain 90% by mass or more and 99.5% by mass or less of methyl methacrylate units and 0.5% by mass or more and 10% by mass or less of acrylic acid ester units.

Examples of acrylic acid esters include methyl acrylate, ethyl acrylate, butyl acrylate, cyclohexyl acrylate, benzyl acrylate, 2-ethylhexyl acrylate, and 2-hydroxyethyl acrylate, with methyl acrylate and ethyl acrylate being preferred.

Acrylic acid ester may be used individually or in combination of two or more types.

As another aspect of the methacrylic polymer, the main chain includes a repeating unit derived from a (meth)acrylic acid ester monomer (hereinafter also referred to as a “(meth)acrylic acid ester unit”) and a structural unit derived from a ring structure (hereinafter referred to as a “ring structure”) and a polymer (A) containing a unit (abbreviated as “unit”). Examples of the ring structural unit include glutaric anhydride structural unit, maleic anhydride structural unit, glutarimide structural unit, lactone ring structural unit, and N-substituted maleimide structural unit.

The ring structural unit may be used individually by one type, or may be used in combination of two or more types.

The lower limit of the content ratio of the (meth)acrylic acid ester unit in the polymer (A) is not particularly limited. From the viewpoint of not damaging the original performance of the acrylic resin, which is that the obtained resin molded body has excellent transparency, processability, and mechanical properties, the total number of repeating units (including structural units; the same applies hereinafter) contained in the polymer (A) With respect to the number of moles (100 mol%), 80 mol% is preferable, 90 mol% is more preferable, and 94 mol% is still more preferable. The upper limit of the content ratio of the (meth)acrylic acid ester unit in the polymer (A) is not particularly limited. From the viewpoint of excellent heat resistance of the obtained resin molded body, 99.999 mol% is preferable, 99.9 mol% is more preferable, and 99.5 mol% is still more preferable, relative to the total number of moles (100 mol%) of repeating units contained in the polymer (A). do. The above upper and lower limits can be arbitrarily combined. For example, 80 to 99.999 mol% is preferable, 90 to 99.9 mol% is more preferable, and 94 to 99.5 mol% is still more preferable.

The lower limit of the content ratio of the ring structural unit in the polymer (A) is not particularly limited. From the viewpoint that the obtained resin molded body has excellent heat resistance, 0.001 mol% is preferable, 0.01 mol% is more preferable, and 0.05 mol% is still more preferable, relative to the total number of moles (100 mol%) of repeating units contained in the polymer (A). do. The upper limit of the content ratio of ring structural units in the polymer (A) is not particularly limited. From the viewpoint that the obtained resin molded body has excellent heat resistance, suppression of molding discoloration, molding appearance, and weather resistance, 10 mol% is preferable, and 3 mol%, relative to the total number of moles (100 mol%) of repeating units contained in the polymer (A). is more preferable, and 0.3 mol% is even more preferable. The above upper and lower limits can be arbitrarily combined. For example, 0.001 to 10 mol% is preferable, 0.01 to 3 mol% is more preferable, and 0.05 to 0.3 mol% is still more preferable.

Examples of (meth)acrylic acid ester forming a (meth)acrylic acid ester unit include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, and iso-propyl (meth)acrylate. , n-butyl (meth)acrylate, iso-butyl (meth)acrylate, sec-butyl (meth)acrylate, tert-butyl (meth)acrylate, n-hexyl (meth)acrylate, cyclohexyl (meth)acrylate ) Acrylate, n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isobornyl (meth)acrylate, glycidyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate , norbornyl (meth)acrylate, adamantyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclofentanyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2 -(meth)acrylate compounds such as hydroxypropyl (meth)acrylate; Compounds having a carboxyl group such as (meth)acrylic acid; and from the viewpoint of improving the thermal stability of the obtained resin molded body, methyl methacrylate is preferable.

(meth)acrylic acid ester may be used individually or in combination of two or more types.

The (meth)acrylic acid ester unit may include a structural unit derived from a monomer having a carboxyl group (hereinafter also referred to as “monomer unit having a carboxyl group”). A monomer unit having a part of a carboxyl group can form a ring structural unit through a cyclization reaction with an ester group, for example, and introduce the ring structural unit into the main chain of the methacrylic polymer. Therefore, the methacrylic polymer may contain a monomer unit having a carboxyl group.

Examples of monomers having a carboxyl group include acrylic acid, methacrylic acid, 2-(hydroxymethyl)acrylic acid, 2-(hydroxyethyl)acrylic acid, and crotonic acid.

The monomer which has a carboxyl group may be used individually by 1 type, or may use 2 or more types together.

In one aspect of the polymer (A), the (meth)acrylic acid ester unit is a repeating unit (A1) derived from methyl methacrylate (hereinafter also referred to as “unit (A1)”), and a repeating unit derived from (meth)acrylic acid. (A2) (hereinafter also referred to as “unit (A2)”) and a polymer containing glutaric anhydride structural unit (A3) (hereinafter also referred to as “unit (A3)”) as a ring structural unit. there is.

When the polymer (A) contains the unit (A3), it is easy to improve the heat resistance of the obtained resin molded body. Unit (A3) is represented by the following chemical structural formula.

In the formula, R ^A and R ^B each independently represent a hydrogen atom or a methyl group.

The lower limit of the content ratio of unit (A1) in polymer (A) is not particularly limited. From the viewpoint of not compromising the original performance of the acrylic resin, which is that the obtained resin molded body has excellent transparency, processability, and mechanical properties, it is used at 80 mol% based on the total number of moles (100 mol%) of the repeating units contained in the polymer (A). is preferable, 90 mol% is more preferable, and 94 mol% is still more preferable. The upper limit of the content ratio of unit (A1) in polymer (A) is not particularly limited. From the viewpoint of excellent heat resistance of the obtained resin molded body, 99.4 mol% is preferable, 99 mol% is more preferable, and 98 mol% is still more preferable with respect to the total number of moles (100 mol%) of repeating units contained in the polymer (A). The above upper and lower limits can be arbitrarily combined. For example, 80 to 99.4 mol% is preferable, 90 to 99 mol% is more preferable, and 94 to 98 mol% is still more preferable.

As the unit (A2), methacrylic acid is preferable because the heat resistance of the obtained resin molded body is excellent.

The lower limit of the content ratio of unit (A2) in polymer (A) is not particularly limited. From the viewpoint of excellent heat resistance and mechanical properties of the obtained resin molded body, 0.5 mol% is preferable, 1 mol% is more preferable, and 2 mol% is further relative to the total number of moles (100 mol%) of repeating units contained in the polymer (A). desirable. The upper limit of the content ratio of unit (A2) in polymer (A) is not particularly limited. From the viewpoint of not damaging the original performance of the acrylic resin, which is excellent in molding appearance, low water absorption, and moldability of the obtained resin molded body, 20 mol% is preferable with respect to the total number of moles (100 mol%) of repeating units contained in the polymer (A). And, 7 mol% is more preferable, and 3.5 mol% is even more preferable. The above upper and lower limits can be arbitrarily combined. For example, 0.5 to 20 mol% is preferable, 1 to 7 mol% is more preferable, and 2 to 3.5 mol% is still more preferable.

The lower limit of the content ratio of unit (A3) in polymer (A) is not particularly limited. From the viewpoint that the obtained resin molded body has excellent heat resistance, 0.001 mol% is preferable, 0.01 mol% is more preferable, and 0.05 mol% is still more preferable, relative to the total number of moles (100 mol%) of repeating units contained in the polymer (A). do. The upper limit of the content ratio of the unit (A3) in the polymer (A) is preferably 10 mol%, more preferably 3 mol%, and 0.3 mol% from the viewpoint of suppressing molding discoloration of the obtained resin molded body and excellent molding appearance and weather resistance. is more preferable. The above upper and lower limits can be arbitrarily combined. For example, 0.001 to 10 mol% is preferable, 0.01 to 3 mol% is more preferable, and 0.05 to 0.3 mol% is still more preferable.

Unit (A3) is a copolymer obtained by copolymerizing methyl methacrylate and (meth)acrylic acid, through a cyclization reaction between the methoxycarbonyl group derived from unit (A1) and the carboxyl group derived from the adjacent unit (A2). It may be a constructed unit.

In the present invention, the content of each unit in the polymer is a value calculated from ¹ H-NMR measurement. Specifically, the method disclosed in International Publication No. 2019/013186 can be used.

The method for producing the polymer containing unit (A1), unit (A2) and unit (A3) is not particularly limited. For example, the manufacturing method disclosed in International Publication No. 2017/022393 and International Publication No. 2019/013186 can be used.

The mass average molecular weight of the methacrylic polymer is not particularly limited. Preferably, it can be 50,000 to 150,000, and 70,000 to 130,000 is preferable. If the mass average molecular weight of the methacrylic polymer is more than the above lower limit, the mechanical properties of the obtained resin molded body are excellent. If the mass average molecular weight of the methacrylic polymer is below the above upper limit, the methacrylic resin composition for hot plate fusion has excellent fluidity.

In the present invention, the mass average molecular weight is a value measured using gel permeation chromatography using standard polystyrene as a standard sample.

In order to control the mass average molecular weight of the methacrylic polymer, it is desirable to adjust the amount of the chain transfer agent in the polymerization of the monomer mixture.

The method for producing methacrylic polymer is not particularly limited. For example, bulk polymerization method, suspension polymerization method, emulsion polymerization method, and solution polymerization method can be mentioned. From the viewpoint of excellent productivity, bulk polymerization method and suspension polymerization method are preferable.

<Fatty acids>

The fatty acid in the present invention prevents stringing from occurring when the resin composition is removed from the hot plate during hot plate fusion, and also improves release properties from the mold during injection molding, preventing peeling residues of the resin composition on the mold surface. This is an ingredient added to make it difficult for . That is, the fatty acid in the present invention is an ingredient that prevents stringing from occurring in the resin composition when removing the resin composition from the hot plate during hot plate fusion, and also provides excellent release properties from the injection mold. am.

Examples of fatty acids include chain hydrocarbon compounds having at least one carboxyl group in the molecule. A chain hydrocarbon compound having at least one carboxyl group in the molecule means a compound in which the carbon atom to which the carboxyl group is bonded is a constituent atom of the carbon chain. The carbon chain in the chain hydrocarbon compound having at least one carboxyl group in the molecule may be saturated or unsaturated, and may be linear or branched.

As the fatty acid, a chain hydrocarbon compound having one carboxyl group is preferable. If there is one carboxyl group, high molecular weight does not occur due to a crosslinking reaction with the reactive functional group of the methacrylic polymer during melt kneading or melt molding, and fluidity is unlikely to decrease.

The upper limit of the 10% weight loss temperature of fatty acids is not particularly limited. From the viewpoint of better release properties from the mold during injection molding and better hot plate adhesion of the obtained resin molded body, 250°C or lower is preferable, 240°C or lower is more preferable, and 230°C or lower is still more preferable. If the 10% weight loss temperature is below the above upper limit, the fatty acid contained in the resin molded body is localized in the melted portion during hot plate fusion, making stringing less likely to occur, and also included in the methacrylic resin composition during injection molding. The fatty acid becomes prone to volatilization within the mold, and as a result, the fatty acid that adheres to the mold surface and is liquefied or condensed diffuses and transfers to the methacrylic resin composition injected into the mold from the rear, resulting in the surface of the finally obtained resin molded body. It is assumed that this is because fatty acids exist in a high content ratio near the surface.

The lower limit of the 10% weight loss temperature of fatty acids is not particularly limited. From the viewpoint of improving releasability from the mold during injection molding and hot plate fusion of the obtained resin molded body, the temperature is preferably 150°C or higher, more preferably 170°C or higher, and even more preferably 200°C or higher. If the 10% weight loss temperature is equal to or higher than the above lower limit, excessive volatilization of fatty acids from the resin molded body during hot plate fusion and a decrease in hot plate release property is suppressed, and during injection molding, the fatty acids volatilized within the mold are suppressed. It adheres to the surface and becomes easily liquefied or condensed, and as a result, the decrease in the amount of fatty acids discharged as gas from the gas vent of the mold is suppressed, and fatty acids are present at a high content rate on the surface and near the surface of the obtained resin molded body. It is assumed that this is because it can be done.

The above upper and lower limits of the 10% weight loss temperature of fatty acids can be arbitrarily combined. For example, the 10% weight loss temperature of the fatty acid is preferably 150 to 250°C, more preferably 170 to 240°C, and even more preferably 200 to 230°C.

The lower limit of the melting point of fatty acids is not particularly limited. From the viewpoint of better release properties from the mold during injection molding and better hot plate adhesion of the obtained resin molded body, 50°C or higher is preferable, 55°C or higher is more preferable, and 60°C or higher is still more preferable. . If the melting point of the fatty acid is above the above lower limit, a decrease in the viscosity of the methacrylic resin composition can be suppressed during hot plate fusion, so stringing becomes difficult to occur, and the fatty acid contained in the methacrylic resin composition is reduced during injection molding. When the resin is filled into the mold, it becomes easy to diffuse within the molten resin, and as a result, the fatty acid that adheres to the mold surface and is liquefied or condensed diffuses and transfers to the methacrylic resin composition injected into the mold from the rear. It is presumed that this is because fatty acids exist at a high content rate on the surface and near the surface of the finally obtained resin molded body.

The upper limit of the melting point of fatty acids is not particularly limited. From the viewpoint of better hot plate fusion properties of the obtained resin molded body, 100°C or lower is preferable, 90°C or lower is more preferable, and 80°C or lower is still more preferable. If the melting point of the fatty acid is below the above upper limit, the stringing suppression effect of the fatty acid in the resin molded body can be easily obtained during hot plate fusion, and the fatty acid volatilized in the mold during injection molding will liquefy or condense on the mold surface. It is presumed that this is because a film layer containing fatty acid is more likely to be formed on the mold surface, and as a result, the above-mentioned actions and effects become easier to obtain.

The above upper and lower limits of the melting point of fatty acids can be arbitrarily combined. For example, the melting point of the fatty acid is preferably 50 to 100°C, more preferably 55 to 90°C, and still more preferably 60 to 80°C.

The molecular weight of fatty acids is not particularly limited. Fatty acids with a molecular weight of 100 to 500 can be used, with 200 to 400 being more preferable. If the molecular weight of the fatty acid is more than the above lower limit, the volatility of the fatty acid is low, so sufficient effects are obtained in terms of release from the mold during injection molding and improvement in hot plate fusion. If the molecular weight of the fatty acid is below the above upper limit, compatibility with the methacrylic polymer is high, so release properties from the mold during injection molding and stringing to the hot plate during hot plate fusion are suppressed, and furthermore, the release property from the hot plate or mold is suppressed. Since the residual fatty acid on the surface of the hot plate or mold decreases when separated, contamination of the surface of the hot plate or mold and clouding of the obtained resin molded body are unlikely to occur.

The number of carbon atoms of the fatty acid is not particularly limited. Preferably, it is 10 to 22. If the carbon number is more than the above lower limit, the volatility of the fatty acid is low, so it becomes difficult to release from the mold during injection molding or stringing when removed from the hot plate during hot plate fusion. If the carbon number is below the above upper limit, the compatibility with the methacrylic polymer is high, so the release property from the mold and the hot plate fusion property are excellent, and there is less fatty acid remaining on the hot plate or mold surface when removed from the hot plate or mold. Therefore, surface contamination of the hot plate or mold or clouding of the obtained resin molded body is unlikely to occur.

Fatty acids include, for example, saturated fatty acids such as lauric acid, palmitic acid, stearic acid, myristic acid, and behenic acid, and unsaturated fatty acids such as oleic acid and linoleic acid. desirable.

Fatty acids may be used individually or in combination of two or more types.

The content of fatty acids in the methacrylic resin composition of the present invention is not particularly limited. It can be 0.01 to 1 part by mass, and 0.1 to 0.3 part by mass is more preferable with respect to 100 parts by mass of the methacrylic polymer. If the fatty acid content is more than the above lower limit, release properties from molds during injection molding and hot plate adhesion tend to improve. If it is below the above upper limit, the residual fatty acid on the surface of the hot plate or mold decreases when it is removed from the hot plate or mold, so it is difficult for surface contamination of the hot plate or mold or clouding of the obtained resin molded body to occur.

The content ratio of fatty acids in the methacrylic resin composition of the present invention is not particularly limited. With respect to the total mass (100 mass%) of the methacrylic resin composition of the present invention, it can be 0.01 to 1 mass%, and 0.1 to 0.3 mass% is more preferable. If the fatty acid content is more than the above lower limit, release properties from molds during injection molding and hot plate adhesion tend to improve. If it is below the above upper limit, the residual fatty acid on the surface of the hot plate or mold decreases when it is removed from the hot plate or mold, so it is difficult for surface contamination of the hot plate or mold or clouding of the obtained resin molded body to occur.

<Other additives>

The methacrylic resin composition of the present invention may contain other additives, such as ultraviolet absorbers, light diffusers, antioxidants, colorants, pigments, dyes, Heat stabilizers, reinforcing agents, fillers, flame retardants, foaming agents, lubricants, plasticizers, and antistatic agents may be contained.

<Method for producing methacrylic resin composition for hot plate fusion>

Examples of the method for producing the methacrylic resin composition of the present invention include the following methods (1) and (2).

(1) A method of mixing a methacrylic polymer and a fatty acid by putting them into a single extruder or a twin-screw extruder, heating, melting, and kneading.

(2) A method of polymerizing a monomer containing methyl methacrylate as a main component by mixing fatty acids.

The methacrylic resin composition of the present invention is less likely to cause stringing when removing the resin composition from the hot plate during hot plate fusion, and is also less likely to generate peeling residue of the resin composition on the mold surface during injection molding. Therefore, the resin molded body obtained by injection molding the methacrylic resin composition of the present invention can be suitably used as a member for hot plate fusion.

<Fusing method>

The fusion method of the present invention includes the steps of melting at least a part of the first member formed from the methacrylic resin composition of the present invention by contacting it with a hot plate, and the step of removing the first member from the hot plate and pressing it with the second member. Equipped with

The material of the second member is not particularly limited as long as it is heat-sealable to the methacrylic polymer of the present invention. Examples include styrene-based resins such as ABS, SAN, AS, and MS resins, polycarbonate-based resins, and polyvinyl chloride-based resins. As the second member, a member formed from the methacrylic resin composition of the present invention can also be used.

1 is a process diagram showing one aspect of the fusion method of the present invention.

A hot plate 3 is disposed between the first member 1 and the second member 2 (Figure 1(a)), and at least a portion of the first member 1 and the second member 2 is used as a hot plate. After contacting (3) and melting them (Figure 1(b)), they are removed from the hot plate 4 (Figure 1(c)), and the melted portion 1a of the first member and the second member are melted. By fusing (compressing) the portion 2a, the first member 1 and the second member 2 can be joined (FIG. 1(d)).

<Vehicle members>

The vehicle member of the present invention includes a composite member formed by adhering a first member and a second member.

The first member in the vehicle member of the present invention contains a methacrylic polymer and a fatty acid. The first member in the vehicle member of the present invention may be a member formed of the methacrylic resin composition of the present invention.

A composite member formed by adhering a first member and a second member may be formed by fusion of the first member and the second member.

Example

Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to these examples.

[Releasability during injection molding]

As an index of release properties during injection molding, the protruding pin pressure was measured by the following method.

The pellet-shaped methacrylic resin composition obtained in the examples and comparative examples was dried with hot air at 80°C for about 16 hours, and then placed in an injection molding machine (model name: EC75-SXII, manufactured by Shibaura Kikai Co., Ltd.) with a cylinder temperature set to 260°C. 1), and a mold provided with a gas outlet portion (vertical diameter 75 mm, thickness 3 mm) can be molded into a disk-shaped molded product 4 (FIG. 2). The disk-shaped mold has a gate portion at the center. Continuous molding was performed under the conditions of a mold temperature of 90°C and an injection pressure of 80 MPa using protruding pins for releasing the molded product, one in the center of the disk-shaped mold and four at equal intervals on the periphery of the mold. was performed, and the protruding pin pressure (unit: MPa) when releasing the molded article 4 from the mold was measured using a pressure sensor installed behind the protruding pin in the central portion. The lower the value of the protruding pin pressure, the better the release property.

[Molding appearance after injection molding]

As an indicator of the molded appearance after injection molding, the presence or absence of peeling defects was observed by the following method.

In the same manner as the evaluation of release properties, the disk-shaped molded article 4 was continuously molded for 40 shots. The surface of the obtained molded article 4 was visually observed, and if even one shot of surface roughness due to poor peeling from the mold was observed on the surface of the molded article 4, it was determined that the molded article 4 had a peeling defect.

[Heat plate adhesion]

As an indicator of hot plate fusion property, stringing property was observed by the following method.

· Test piece production: For evaluation of release properties, the sprue portion 5 was cut from the disk-shaped molded product 4 (vertical diameter 75 mm, thickness 3 mm), and a cone-shaped test piece 6 (bottom diameter 10 mm) was made. , height 70 mm) was manufactured (see Figures 2 and 3).

· Hot plate: A plate made of SUS304 was laid on the hot plate 7, and this was used as the hot plate 8. Temperature control of the surface of the hot plate 8 was performed by actually measuring the surface temperature of the hot plate 8 with a probe-type thermometer.

· Test method: After heating the surface temperature of the hot plate 8 to 260°C, the bottom part 9 (10 mm in diameter) of the cone-shaped test piece 6 is brought into contact with the surface of the hot plate 8 for 20 seconds. , After melting the contact portion, the test piece 6 was lifted to a height of 30 cm to confirm the presence or absence of stringing between the test piece 6 and the hot plate 8 (see Figure 4). Stringing is a part of a thread-shaped methacrylic resin composition. Five test pieces were prepared, the above operation was performed once for each test piece, and judgment was made according to the following criteria.

(Criteria)

A: Stringing occurs 0 times

B: Stringing present 1 to 2 times

C: Stringing present 3 to 5 times

<Melting point>

The melting point of the fatty acid was evaluated by the following method using a differential scanning calorimeter (DSC) (manufactured by Seiko Instruments, model: DSC-6200).

Approximately 10 mg of fatty acid was placed in an aluminum sample container, raised to 200°C at a temperature increase rate of 10°C/min, held for 5 minutes to melt, then lowered to 0°C at a temperature increase rate of 10°C/min, and again at a temperature increase rate of 10°C. The temperature was raised at a rate of 10°C/min, held for 5 minutes, and lowered at a rate of 10°C/min, and the maximum point of the crystal melting peak observed at this time was referred to as the melting point of the fatty acid.

<10% weight loss temperature>

The 10% weight loss temperature of the fatty acid was measured according to the following method using a thermogravimetric device (TGA) (manufactured by Seiko Instruments Co., Ltd., model: TG/DTA6200). While flowing dry nitrogen at 100 ml/min, the temperature was raised from 40°C to 500°C at a temperature increase rate of 10°C/min, and the temperature at which the weight reduction rate was 10% (a 10 mass% decrease in weight) was measured.

(Raw materials)

The abbreviations of the compounds used in the examples and comparative examples are as follows.

MMA: Methyl methacrylate (brand name: Acryester (registered trademark) M, manufactured by Mitsubishi Chemical Co., Ltd.)

MA: Methyl acrylate (manufactured by Mitsubishi Chemical Co., Ltd.)

MAA: methacrylic acid

Polymerization initiator (1): 2,2'-azobis(2-methylpropionamidine) dihydrochloride

Polymerization initiator (2): 2,2'-azobis-2-methylbutyronitrile (brand name: V-59, manufactured by Wako Pure Chemical Industries, Ltd.)

Chain transfer agent (1): n-octyl mercaptan (manufactured by Tokyo Kasei Kogyo Co., Ltd.)

Polymer (1): Acrypet (registered trademark) VH (brand name, Mitsubishi Chemical Co., Ltd., acrylic resin containing 98% by mass of methyl methacrylate units)

Polymer (2): Methacrylic polymer prepared in Preparation Example 1

Fatty acid compound (B-1): Myristic acid (Product name: LunacMY-98, manufactured by Gao Corporation)

Fatty acid compound (B-2): palmitic acid (brand name: Lunac P-95, manufactured by Gao Corporation)

Fatty acid compound (B-3): Stearic acid (Product name: Lunac S-98, manufactured by Gao Corporation)

Fatty acid compound (B-4): Myristyl alcohol (Product name: Calcol 4098, manufactured by Gao Corporation)

Fatty acid compound (B-5): Cetyl alcohol (Product name: Calcol 6098, manufactured by Gao Corporation)

Fatty acid compound (B-6): Stearyl alcohol (Product name: Calcol 8098, manufactured by Gao Corporation)

Fatty acid compound (B-7): Glycerin monostearate (Product name: Rickemar S100A, manufactured by Ricken Vitamin Company)

Fatty acid compound (B-8): Glycerin mono-distearate (Product name: Rickemar S200A, manufactured by Ricken Vitamin Co., Ltd.)

Fatty acid compound (B-9): Stearyl stearate (Product name: Rickemar SL-900A, manufactured by Ricken Vitamin Company)

Fatty acid compound (B-10): Stearic acid amide (Product name: Fatty acid amide S, manufactured by Gao Corporation)

[Production Example 1]

900 parts by mass of deionized water, 60 parts by mass of sodium 2-sulfoethyl methacrylate, 10 parts by mass of potassium methacrylate, and 12 parts by mass of MMA were added to a reaction vessel having a reflux condenser whose interior was purged with nitrogen, and then added to the reaction vessel while stirring. The temperature was raised so that the liquid temperature inside was 50°C. After that, 0.08 parts by mass of polymerization initiator (1) was added, the temperature was raised while stirring so that the liquid temperature in the reaction vessel was 60°C, and then, using a dropping pump, MMA was continuously added dropwise over 75 minutes at a rate of 0.24 parts by mass/min. did. After that, it was held for another 6 hours and polymerization was performed to obtain a dispersant (solid content: 10% by mass).

2000 parts by mass of deionized water and 4.2 parts by mass of sodium sulfate were added to a reaction vessel equipped with a reflux condenser equipped with a nitrogen gas introduction tube, and then stirred at a stirring speed of 320 rpm for 15 minutes. After that, a mixed solution of 1351.6 parts by mass of MMA, 36.3 parts by mass of MAA, 12.1 parts by mass of MA, 2.8 parts by mass of polymerization initiator (2), and 4.2 parts by mass of chain transfer agent (1) was added to the reaction vessel and stirred for 5 minutes. Next, 6.72 parts by mass of the dispersant (solid content 10% by mass) prepared in Production Example 1 was added to the reaction container, and then stirred to disperse the monomer composition in the reaction container in water. After that, the inside of the reaction vessel was purged with nitrogen.

Next, after raising the temperature of the liquid in the reaction vessel to 75°C, the temperature of the liquid in the reaction vessel was continuously measured again and maintained at 75°C until the polymerization exothermic peak was observed. After the polymerization exothermic peak was observed, the temperature of the liquid in the reaction vessel was raised to 90°C and maintained for 60 minutes to perform polymerization. After that, the mixture in the reaction vessel was filtered, the filtrate was washed with deionized water, and dried at 80°C for 16 hours to obtain a bead-shaped copolymer, which was used as a precursor for methacrylic resin (copolymer precursor (1) ) said.

The composition of the copolymer precursor (1) was analyzed according to the measurement method of “content of units (A), (B), and (C)” described above, and was found to contain 96.0 mol% of MMA units and a repeating unit derived from methacrylic acid ( (hereinafter referred to as “MAA unit”) was 3.0 mol%, and the repeating unit derived from methyl acrylate (hereinafter referred to as “MA unit”) was 1.0 mol%.

The copolymer precursor (1) was supplied to a twin-screw extruder (model name "PCM30", manufactured by Ikegai Co., Ltd.) and kneaded at 250°C to obtain a pellet-shaped methacrylic polymer, which was referred to as polymer (2). .

The composition of the obtained polymer (2) was 97.00 mol% of MMA units, 2.99 mol% of (meth)acrylic acid units, and 0.01 mol% of glutaric anhydride structural units. Additionally, (meth)acrylic acid units include MAA units and MA units.

[Example 1]

100 parts by mass of polymer (1) and 0.1 part by mass of fatty acid compound (B-1) as a fatty acid were supplied to a twin screw extruder (model name “TEM35”, manufactured by Shibaura Kikai Co., Ltd.), and the cylinder temperature of the extruder was set to 250°C. By melt-kneading, a pellet-shaped methacrylic resin composition was obtained at a mold temperature of 60°C.

The evaluation results of the obtained methacrylic resin composition are shown in Table 1.

[Reference Example 1]

Except that fatty acid was not used, the same procedure as in Example 1 was performed to obtain a pellet-shaped methacrylic resin composition.

The evaluation results of the obtained methacrylic resin composition are shown in Table 1.

[Examples 2 to 3, Comparative Examples 1 to 7]

Except for changing the type of fatty acid compound, the same procedure as in Example 1 was performed to obtain a pellet-shaped methacrylic resin composition.

The evaluation results of the obtained methacrylic resin composition are shown in Table 1.

[Example 4, Comparative Examples 8 to 9]

The same procedure as in Example 1 was performed except that polymer (2) was used instead of polymer (1) and the type and addition amount of the fatty acid compound were changed, thereby obtaining a pellet-shaped methacrylic resin composition.

The evaluation results of the obtained methacrylic resin composition are shown in Table 1.

The resin molded bodies of Examples 1 to 4 were excellent in release properties and hot plate fusion properties during injection molding.

Since the resin molded body of Reference Example 1 did not contain fatty acid, release properties during injection molding and hot plate fusion were inferior.

The resin molded bodies of Comparative Examples 1 to 9 contained a fatty acid compound, but since no fatty acid was used, release properties during injection molding and hot plate fusion were inferior.

The methacrylic resin composition for hot plate fusion of the present invention is unlikely to cause stringing when the resin composition is removed from the hot plate during hot plate fusion, and has excellent hot plate fusion properties. Additionally, peeling residues of the resin composition are unlikely to occur on the mold surface during injection molding, and release properties from the mold are excellent. Therefore, the molded body containing the methacrylic resin composition for hot plate fusion of the present invention can be used as vehicle members such as vehicle interior and exterior materials such as tail lamp covers, head lamp covers, and meter panels; architectural absence; It can be suitably used as a raw material for home equipment members such as washbasins, bathtubs, and flushing toilets, and is particularly suitable as a raw material for vehicle members.

Examples of vehicle parts include tail lamp covers, head lamp covers, meter panels, door mirror housings, pillar covers (sash covers), license garnishes, front grills, fog garnishes, and emblems.

1: first member
1a: molten part of the first member
2: Second member
2a: melted portion of the second member
3: heating plate
4: Disc-shaped molded product
5: Sprue part
6: Cone-shaped test piece
7: hot plate
8: heating plate
9: bottom part
10: Stringing between the test piece and the heating plate

Claims (17)

A methacrylic resin composition for hot plate fusion, comprising a methacrylic polymer and a fatty acid. The methacrylic resin composition for hot plate fusion according to claim 1, wherein the fatty acid has a carbon number of 10 to 22. The methacrylic resin composition for hot plate fusion according to claim 1 or 2, wherein the 10% weight loss temperature of the fatty acid is 250°C or lower. The methacrylic resin composition for hot plate fusion according to any one of claims 1 to 3, wherein the fatty acid has a melting point of 50°C or higher. The methacrylic resin composition for hot plate fusion according to any one of claims 1 to 4, wherein the fatty acid is a chain hydrocarbon compound having at least one carboxyl group in the molecule. The methacrylic resin composition for hot plate fusion according to any one of claims 1 to 5, wherein the fatty acid has a molecular weight of 100 to 500. The methacrylic resin composition for hot plate fusion according to any one of claims 1 to 6, wherein the content of the fatty acid is 0.01 to 1 part by mass based on 100 parts by mass of the methacrylic polymer. The meta for hot plate fusion according to any one of claims 1 to 6, wherein the fatty acid content is 0.01 to 1% by mass relative to the total mass (100% by mass) of the methacrylic resin composition for hot plate fusion. Krill-based resin composition. The methacrylic resin composition for hot plate fusion according to any one of claims 1 to 8, wherein the fatty acid contains at least one selected from stearic acid, palmitic acid, and myristic acid. The method according to any one of claims 1 to 9, wherein the methacrylic polymer contains a repeating unit derived from methyl methacrylate, and the content ratio of the repeating unit derived from the methyl methacrylate in the methacrylic polymer. A methacrylic resin composition for hot plate fusion that is 70% by mass or more. The method according to any one of claims 1 to 10, wherein the methacrylic polymer is a polymer (A) comprising a repeating unit derived from a (meth)acrylic acid ester monomer and a structural unit derived from a ring structure,
The structural unit derived from the ring structure contains at least one selected from the group consisting of a glutaric anhydride structural unit, a maleic anhydride structural unit, a glutarimide structural unit, a lactone ring structural unit, and an N-substituted maleimide structural unit. Methacrylic resin composition for hot plate fusion. The polymer (A) according to claim 11, wherein the polymer (A) contains a repeating unit derived from methyl methacrylate (A1), a repeating unit derived from (meth)acrylic acid (A2), and a glutaric anhydride structural unit (A3). Methacrylic resin composition for hot plate fusion. The methacrylic resin composition for hot plate fusion according to any one of claims 1 to 12, which is used as a raw material for vehicle members. The methacrylic resin composition for hot plate fusion according to claim 13, wherein the vehicle member is at least one selected from a tail lamp cover, a head lamp cover, and a meter panel. Use of the methacrylic resin composition for hot plate fusion according to any one of claims 1 to 14 for hot plate fusion. A step of melting at least a portion of the first member formed of the methacrylic resin composition for hot plate fusion according to any one of claims 1 to 14 by contacting it with a hot plate;
A method of fusing a first member and a second member, comprising the step of removing the first member from the hot plate and pressing it with the second member. A vehicle member comprising a composite member formed by adhering a first member and a second member,
A vehicle member wherein the first member contains a methacrylic polymer and a fatty acid.

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